730R87102
es
cimiunmental Protection
Agency
Office of Pesticides
and Toxic Substances
Washington, DC 20460
December 1987
Pesticides and Toxic Substances
Agricultural Chemicals in Ground Water:
Proposed Pesticide Strategy
o
M
Wft*
o
^Vť>:
- r rjf
f,
-------
r-0
) AGRICULTURAL CHEMICALS IN GROUND WATER:
-e , -f
/
PROPOSED PESTICIDES STRATEGY
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDES AND TOXIC SUBSTANCES
DECEMBER 1987
-------
TO THE READER:
This document contains the Environmental Protection Agency1s proposed
strategy for addressing the pesticides in ground water concern. The Agency is
seeking public comment on the policies and approaches proposed in this
document before developing a final strategy.
EPA's proposed strategy envisions national registration of pesticides with
State- or county-wide restrictions based on ground-water concerns. EPA will
also establish ground-water protection measures that will be uniformly
applicable across the country. Still other management measures will be
applicable only at sites with certain conditions (e.g., shallow water tables,
location within wellhead protection areas).
EPA's registration decisions will be based on preventing unreasonable
risks from ground-water contamination. The Agency proposes to use Maximum
Contaminant Levels (MCLs), as established under the Safe Drinking Water Act,
as reference points in helping determine the levels of ground-water
contamination that would pose unreasonable risks if found in an underground
source of drinking water. When MCLs are not yet available for certain
pesticides, EPA proposes to use interim protection criteria, established by
the Agency's drinking water health advisories, as its reference points. In
addition to these reference points, a number of other factors will obviously
need to be considered, including the benefits of a pesticide's use, when the
Agency determines if a pesticide's potential to contaminate ground water poses
an unreasonable risk. Nevertheless, these reference points will be important
benchmarks for triggering reviews that will determine the need for pesticide
management measures.
-------
"TO THE READER"
Page 2
EPA's proposed strategy also provides interested and qualified States the
opportunity to take the lead role in further refining the Agency's analysis
and decisionmaking process. In this lead role, a State could tailor the
conditions of pesticide use to specific local ground-water protection needs
including such factors as hydrogeologic vulnerability which can vary greatly
within counties. If appropriate, a State could permit use of certain
pesticides in areas that EPA's registration decision would otherwise not
allow. In such cases, EPA would modify the Federal registration to
accommodate the State plan.
The Agency is particularly interested in receiving comments and
recommendations on the following key issues regarding its strategy:
1. Determination of unreasonable health and environmental risks posed by
pesticide contamination of ground water and the need for pesticide
management measures to prevent such contamination.
t Is it appropriate to use reference points, as described in the
strategy, to trigger pesticide management measures? Are the
risk levels represented by these reference points appropriate
for this purpose? Would a range of levels, coupled with other
considerations such as the extent of exposures, be more
appropriate reference points?
Should different levels of protection be afforded ground-water
resources based on whether they are a current or potential
drinking water source? Should protection of potential drinking
water differ depending on the degree of likelihood of future
use? What factors should be considered when assessing the
potential for a ground-water resource to be a future drinking
water supply?
-------
"TO THE READER"
Page 3
2. Roles and responsibilities of EPA and the States.
What role should a State have in assessing and balancing
pesticide risks and benefits when there are local ground-water
concerns? Should a State have the responsibility for
determining what ground waters will receive what level of
protection?
To what extent should EPA oversee a State's plan to manage
pesticide use to protect its ground-water resources? Under what
circumstances should EPA consider cancelling the use of a
pesticide in a State even if that State has a plan to manage the
pesticide?
t To what extent should EPA and the States concentrate on
chemical-specific plans? Under what circumstances should a
State undertake, and EPA accept, a generic plan for pesticides
management in lieu of chemical-specific plans?
Reviewers should submit their comments on these and other issues raised by
the Agency's proposed strategy to:
Ground Water Strategy Project
Office of Pesticides Programs
U.S. EPA (TS-766C)
401 M Street, S.W.
Washington, D.C. 20460
EPA has attempted to address the issues involving the pesticides in ground
water concern as fully and as openly as possible. It is our hope that this
document will elicit extensive public review and comment.
-------
PREFACE
Pesticides contribute significantly to improved crop productivity and to
public health by controlling a wide variety of pests. Each year, about 3.5
billion pounds of formulated pesticide products are used in this country to
control harmful microorganisms, weeds, insects and rodents. While the benefits
derived from the use of pesticides are considerable, these chemicals can also
pose risks to human health and the environment.
There has been increasing concern for the potential risks posed by the
detection of pesticides in ground water. Along with other Federal agencies and
the States, EPA has initiated a number of efforts to better define this
environmental concern. EPA has also undertaken the development of a strategy
to ensure that the potential health and environmental impacts resulting from
ground-water contamination are fully considered in pesticide registration
decisions so that unreasonable risks can be identified and avoided. This
document presents the Agency's proposed strategy for formal public review and
comment.
Before reviewing this document, it is useful to understand four Agency
tenets that form the underlying basis of the proposed strategy:
1) EPA considers the benefits as well as the risks of a pesticide's use.
Congress recognized that the use of pesticides entails both risks and
benefits when it established the Federal Insecticide, Fungicide and
Rodenticide Act (FIFRA) as the basic law governing the use of
pesticides in this country. Under FIFRA, EPA considers the benefits
as well as the risks in the registration or licensing of a pesticide's
use. In those circumstances where EPA determines that unreasonable
risks are posed by a pesticide's use, the Agency takes steps to reduce
the risks through regulatory action including, if necessary,
cancelling or denying the registered use of a pesticide.
(1)
PROPOSED STRATEGY
-------
It is important to note that the mere presence of a pesticide residue
in food, drinking water or the general environment does not
necessarily present an unreasonable risk. The level of risk posed by
pesticide residues is dependent upon the levels and duration of human
exposures to residues of the pesticide and the toxicological
significance of such exposures.
Once the potential risk posed by a pesticide's use is quantified, it
must then be compared to the benefits derived from the use of the
pesticide to determine if such risks are "unreasonable" as required by
the FIFRA statute. However, prudent pesticide management requires the
consideration of measures to minimize unnecessary exposures.
2) EPA pesticide registrations are national decisions that define the
specific uses of individual pesticide products. For agricultural
uses, a pesticide product must be registered for each specific type of
crop on which the manufacturer or registrant intends it to be used.
Historically, these registered uses of a pesticide and the conditions
of their registration (e.g., rate, timing and method of application)
have been uniformly applicable across the nation. A national basis
for pesticide registration decisions has been found to be generally
appropriate for addressing both unacceptable dietary and applicator
risks.
Given the national food distribution system in this country, EPA
generally employs average national exposure levels to assess and
manage dietary risks to either the total population or certain
sensitive subpopulations (e.g., infants). For applicator risks, the
Agency employs a national approach because the two key factors in
examining such exposures, the properties of a pesticide (i.e.,
toxicity and potential for dermal absorption or inhalation) and
applicator practices (i.e., method of application and use of
(11)
PROPOSED STRATEGY
-------
protective clothing), generally do not significantly vary with
location. As described below and in the strategy, such national
approaches to risk assessment and management may not be appropriate
for addressing the pesticides in ground water concern.
3) EPA attempts to reduce net pesticide risk. While EPA's registration
decisions are generally made on a chemical-by-chemical basis, the
Agency attempts to assess the risks of a pesticide with the objective
of net risk reduction for all pesticide use. As such, the Agency
examines the risks and benefits posed by alternative pesticides and
determines if there may be certain "risk-risk trade-offs," i.e., a
decrease in the risks posed by one type of exposure results in an
increase in risk through another type of exposure.
4) An exact assessment of the potential for "unreasonable risks"
resulting from ground-water contamination would require consideration
of a number of factors including; 1) local ground-water vulnera-
bility; 2) the use and value of the local ground water; 3) resulting
local health and economic impacts; and 4) the local benefits of the
pesticide's use posing the potential risk. The vulnerability of
ground water to pesticide contamination is dependent on a variety of
site-specific factors including the hydrogeology of the area, the
types and manner of pesticide use, and other farming practices, such
as irrigation. The degree of risk posed by such contamination will
depend on the local levels of contamination and the extent of human
exposure. Finally, whether or not the risk is "unreasonable" will
depend on the significance of the risk in the context of the benefits
derived from the pesticide use.
As has been the case with certain pesticides, contamination of ground
water can occur in numerous locations throughout the country. In some
of these locations, agricultural production may be highly dependent on
the use of a pesticide, and the risk of ground-water contamination may
be considered reasonable particularly if the likelihood of significant
(111)
PROPOSED STRATEGY
-------
exposures is minimal. In other circumstances, the benefits of a
pesticide's use may be modest and ground-water contamination may be
found to pose unreasonable risks particularly if there is the
possibility for significant human exposures.
There are a number of additional considerations that should be
included in an assessment of the local impacts of ground-water
contamination. In some hydrogeologic settings, ground-water
contamination may persist for years after a pesticide's use has
stopped and thus, there is the potential for long-term exposures.
Because of limited predictive capability and the high cost of
monitoring, such exposures could remain undetected in some areas for
long periods of time. It can be expensive for individual or local
community well users to obtain alternative water supplies, effectively
treat the water to reduce pesticide residues to acceptable levels, or
restore the quality of ground water to acceptable levels. At the same
time, however, the use of pesticides in these locations may be
essential to the farmer's ability to grow crops.
Together, these four tenets raise a number of issues that the Agency must
address in developing its strategy. The primary issue is how, and to what
level of geographical refinement, the risks and benefits of a pesticide's use
should be assessed when it has the potential to contaminate ground water.
EPA's traditional way of assessing and managing national pesticide risks and
benefits is not easily adapted to evaluating localized concerns. Unlike
dietary and applicator pesticide exposures, the potential for exposures through
ground-water contamination can vary widely across the country. From a national
viewpoint, the number of people potentially exposed to pesticide residues
through ground-water contamination is limited in comparison to dietary
exposures. However, in those areas where ground-water contamination occurs,
the local health and economic consequences can be substantial. Furthermore, in
some cases, there is the possibility that a significant number of areas may
experience such contamination for some time before it is detected.
(iv)
PROPOSED STRATEGY
-------
How should EPA evaluate and weigh a pesticide's risks and benefits when the
use of that chemical can result in ground-water contamination? What role
should a State have in making these determinations and managing pesticides to
avoid the problem?
As presented in this document, EPA's proposed strategy envisions the
national registration of pesticides with county-wide or State-wide restrictions
due to ground-water concerns. The risk-benefit determinations underlying these
EPA-determined geographic prohibitions will be rather crude and dependent on
the use of drinking water standards or health advisories and ground-water
classification schemes as general points-of-reference. The proposed strategy,
however, also offers each interested and qualified state the opportunity to
take the lead role in further refining the Agency's analysis and
decision-making process. In this lead role, a State could tailor the
conditions of pesticide use to specific local ground-water protection needs.
In some cases, a State might propose to allow the use of a pesticide in an area
that EPA would otherwise not allow. A State could employ land use planning and
ground-water classification in addition to specific hydrogeologic and crop use
patterns to refine pesticide management decisions. Where found appropriate,
EPA would consider modifying the Federal registration to accommodate the state
program.
A wide range of agricultural ground-water experts, including managers and
scientists from Federal and State agencies, and representatives from farm,
industry and environmental interest groups, and research and educational
institutions, were consulted as the Agency undertook the development of this
proposed strategy. The Agency held a major workshop in the summer of 1986 with
these experts to solicit their opinions and recommendations. The Agency also
talked extensively with the members of Congress and their staffs on approaches
to this environmental issue. The Agency developed a draft proposal and invited
the participants from the previous workshop, along with Congressional staff and
additional State representatives to review the proposal in a second workshop
held last summer. At this time, EPA is seeking broad public comment on the
policies and approaches of this proposed Agency strategy.
(v)
PROPOSED STRATEGY
-------
TABLE OF CONTENTS
Page
PREFACE 1
EXECUTIVE SUMMARY 1
PROBLEM ASSESSMENT SUMMARY 11
Chapter 1: Ground Water - The Resource 13
Chapter 2: Pesticides in Ground Water -
The Concern 21
Chapter 3: Pesticides in Ground Water -
Causative Factors 29
Chapter 4: Statutory Authorities
and Institutional Framework 41
Chapter 5: Conclusion 47
PROPOSED PESTICIDES STRATEGY 53
Chapter 1: Environmental Goal 59
Section 1: Factors and Options Considered 59
Section 2: EPA's Proposed Policy Position 74
Chapter 2: Prevention Policy and Program 85
Section 1: Factors and Options Considered 86
Section 2: EPA's Proposed Policy Position 102
Chapter 3: Response Policy and Program 119
Section 1: Factors Considered 119
Section 2: EPA's Proposed Policy Position 121
IMPLEMENTATION ISSUES 131
Chapter 1: Implementation - Environmental Goal 133
Chapter 2: Implementation - Prevention Program 139
Chapter 3: Implementation - Response Program 147
PROPOSED STRATEGY
-------
FIGURES
1-1 Trends in Ground-Water Withdrawals 15
1-2 Illustration of Relationships within the
Hydrogeologic System 16
1-3 Productive Aquifers and Withdrawals from
Wells in the United States 18
1-4 Numbers of Pesticides Found 24
1-5 U.S. Pesticide Total Use 33
1-6 Categories of Ground-Water Vulnerability 37
1-7 Map of Ground-Water Pollution Potential, Portage
County, Wisconsin 38
1-8 EPA Offices Working to Protect Ground Water 43
II-l Pesticide Strategy 54
II-2 Pesticide Strategy Process 56
II-3 Goal Definition Issues 60
II-4 What Waters to Protect 63
11-5 What Waters to Target for Protection 64
11-6 Zones of Subsurface Water 66
II-7 Goal: Varied Legislative Direction 68
II-8 Basic Protection Criteria Options 71
II-9 What Waters to Target - EPA Policy 76
11-10 What Criteria Determine Protection 79
11-11 EPA'S "Yellow Light/Red Light" Approach 81
11-12 Prevention Program Issues 87
11-13 "Ideal" Protection 90
11-14 a) Uniform Protection: High Vulnerability 91
b) Uniform Protection: Medium Vulnerability 91
11-15 Tailored Preventive Measures 93
11-16 Levels of Resolution 95
11-17 Levels of Resolution and Decisions 96
11-18 a) Roles and Responsibilities: Option A 98
b) Roles and Responsibilities: Option B 99
c) Roles and Responsibilities: Option C 101
11-19 "Yellow Light/Red Light" Approach 115
11-20 Response Program Issues 120
III-l Implementation Issues 132
III-2 Key Goal Implementation Issues 134
III-3 Key Prevention Implementation Issues 140
III-4 Key Response Implementation Issues 148
PROPOSED STRATEGY
-------
TABLES
1-1 Examples of Key Reports 12
1-2 Percentages of People Relying on Ground Water 14
1-3 Pesticides Found in Ground Waters of 24 States 23
1-4 Potential Sources of Pesticide Contamination 30
1-5 Volume of U.S. Pesticides Used by Class and Sector 32
11-1 State Management Menu 107
II-2 Comparison of Possible Outcomes for Pesticide
Use in a State 109
II-3 Responsibilities in the Strategic Prevention Approach 112
II-4 Indirect EPA Response Options 124
II-5 EPA's Response Strategy 128
III-l Indirect EPA Response Options 149
PROPOSED STRATEGY
-------
EXECUTIVE SUMMARY
-------
EXECUTIVE SUMMARY
This document presents EPA's proposed strategic plan for protecting ground
water from contamination by pesticides. It is divided into three parts: (1)
a brief summary assessment of the problem; (2) the proposed Agency strategy;
and (3) an outline of implementation issues and questions. At this time, EPA
is seeking comments on all three parts of the document, including: the find-
ings and assumptions of the summary problem assessment; the proposed policies
and programs of the Agency's pesticides strategy; and the implementation ques-
tions and issues raised by the Agency's proposed strategic approach.
SUMMARY PROBLEM ASSESSMENT
Ground water is a valuable national resource which can be vulnerable to
contamination by pesticides from normal agricultural use as well as from
leaks, spills and disposal. Although the full extent of the problem is not
known, enough information has been reported to indicate that the problem is
widespread in certain areas of the country. Most findings of pesticides in
ground water have been at relatively low levels, although some significant
levels have been reported in some areas, resulting in numerous well closings.
The full scope of the health and environmental effects associated with
pesticides in ground water remains unclear at this time and may not be known
for several years. What is clear, however, is that once widespread
contamination of ground water by pesticides has occurred, it is often not
economically or technically feasible to restore the resource. Even provisions
of alternative drinking water or treatment to remove contamination from
drinking water before it is used may be impracticable if contamination is
widespread. For these reasons, prevention of unacceptable contamination must
be the primary focus of protection efforts.
The potential vulnerability of ground water to pesticide contamination is
determined by a complex set of factors which vary significantly from area to
area. Furthermore, the use and value of ground waters vary considerably
across the country. In some areas, ground water provides an irreplaceable
1
PROPOSED STRATEGY
-------
source of drinking water for large populations, while in other areas, ground
water is essentially unusable. These highly variable characteristics of the
ground-water resource and the area-specific nature of the pesticide
contamination concern suggest the need for a localized protection approach.
The number and complexity of Federal and State programs and statutory
authorities which may be used to address the pesticides in ground-water
concern is substantial. Currently, EPA administers five major environmental
statutes that address some aspect of pesticide contamination in ground water,
including the:
Federal Insecticide, Fungicide and Rodenticide Act (FIFRA)
Safe Drinking Water Act (SOWA)
Clean Water Act (CWA)
Resource Conservation and Recovery Act (RCRA);
Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA)
In addition to EPA, other Federal agencies, such as the U.S. Department of
Agriculture (USDA) and the U.S. Geological Survey (USGS) of the Department of
Interior, are key institutions in addressing this issue. And just as
important, the States have a major role to play in addressing ground-water
contamination. Here again, at the State level a number of different agencies
and statutes are involved in the protection of ground water and pesticides
management. A number of States have already taken aggressive action in
dealing with the concern for ground-water contamination by pesticides.
Protection of ground water from pesticide contamination will require a co-
ordinated approach among these Federal and State agencies. Development of a
comprehensive strategy is one of the first steps needed in moving toward an
integrated and successful management approach.
2
PROPOSED STRATEGY
-------
PESTICIDES STRATEGY
The purpose of the strategy is to articulate EPA's long-term approach for
managing the pesticides in ground-water concern. The proposed strategy is or-
ganized into three chapters that address the key issues associated with: the
Agency's environmental goal; its prevention strategy; and its response
strategy. Each of these chapters first describes the factors and options
which EPA considered, followed by a detailed description of the Agency's
proposed policy choices. The Agency made its policy choices based on
consideration of its legislative statutes, its long-term policies for
pesticides registration, and its general Ground-Water Protection Strategy
(1984).
Environmental Goal: EPA's environmental goal will be to manage the use of
pesticides to protect the ground-water resource. Specific attention will be
given to preventing unacceptable contamination of current and potential
drinking water supplies. The Agency will use MCLs or other EPA-designated
protection criteria as reference points for helping to determine unacceptable
contamination of ground water. Specifically, the Agency will adopt the
following policies as its environmental goal for protecting ground water from
pesticide contamination:
1. The Agency will use a differential protection approach to protect the
ground-water resource. With this approach, the Agency will apply
protective efforts to those waters that are a current or potential
source of drinking water or that are vital to fragile ecosystems.
Additional measures may be taken to ensure protection of certain "high
priority ground waters."
2. EPA will use MCLs, as defined under the SDWA, as reference points for
helping to determine unacceptable contamination of ground water that
is a drinking water source. When no MCL exists, EPA will use interim
drinking water protection criteria as its reference points. These
will be equivalent to an MCLG for noncarcinogenic pesticides and to a
3
PROPOSED STRATEGY
-------
negligible risk level for carcinogenic pesticides. The Agency will
also use ecologically based protection criteria as reference points
for helping to determine unacceptable ground-water contamination.
Prevention Policy and Program: The Agency's proposed strategy to prevent
unacceptable pesticide contamination of ground water will be based on a
muHi pronged management approach with varied Federal-State roles.
Specifically, EPA's prevention strategy will consist of the following
policies:
1. EPA will continue to take uniform action for pesticides posing wide-
spread, national concerns and will establish generic prevention
measures to address certain pesticide use and disposal practices that
pose unique ground-water threats independent of local vulnerability.
2. EPA will also adopt a new approach of differential management of pes-
ticide use based on differences in ground-water use, value and
vulnerability to an extent that is administratively feasible.
County-level or State-level measures, based on ground-water
vulnerability, will be employed including use cancellations. In some
cases, the user will have to determine the applicability of
differential prevention measures based on local field conditions or
the user's location in an area of "high priority ground waters" (i.e.,
high use and value ground waters).
3. EPA will encourage the development of a strong State role in local
management of pesticide use to protect the ground-water resource.
State pesticide management plans will be used to strengthen EPA's
foundation for pesticide registration decisions. In some cases, the
registered use of a pesticide in a State will depend on the presence
and adequacy of such a State management plan. Under a management
plan, a State will have the opportunity to develop and implement
highly tailored prevention measures based on area-specific differences
in ground-water use, value and vulnerability.
4
PROPOSED STRATEGY
-------
4. The user's role in preventing ground-water contamination is pivitol;
users will be provided with better information and training to enable
them to make environmentally sound decisions.
5. Registrant responsibilities will need to increase in three areas: (1)
technical support of the user in the field; (2) ground-water
monitoring to ensure the adequacy of pesticide management plans in
protecting ground water; and (3) the development of safer alternative
pesticides.
6. Increased monitoring of pesticides in ground waters is critical to the
implementation of this strategy. EPA will establish an "early-
warning" or "yellow light/red light" approach to prevent further area
contamination once it is detected. Under this system, MCLs or other
EPA-specified protection criteria will be used as reference points to
evaluate, and when necessary, change pesticide management plans.
Response Policy and Program: The Agency's policy for responding to pesticide
contamination of ground water emphasizes Federal-State coordination and
statutory enforcement activities. More specifically, these policies include:
1. Where a pesticide has reached unacceptable levels in ground water,
strong actions are to be taken to stop further contamination. These
actions can range from enforcement measures to modification of the way
a pesticide is managed, including geographic restrictions of the
pesticide's use.
2. EPA will encourage a strong State role in responding to contamination.
A State's management plan should consider the development of a valid
corrective response scheme.
3. EPA will continue to develop and emphasize enforcement of MCLs to pro-
tect users of public drinking water systems. Under SDWA's emergency
powers, EPA will consider issuing orders requiring responsible parties
to provide alternative water supplies when levels of pesticides
present an imminent and substantial endangerment to public health.
5
PROPOSED STRATEGY
-------
4. EPA and the States will place greater emphasis on coordinating FIFRA,
SDWA, and CERCLA enforcement activities to identify parties
responsible for ground-water contamination as a result of the misuse
of pesticides, including illegal disposal or leaks and spills.
5. On a case-by-case basis, EPA may assist States by undertaking CERCLA
Fund financed removal actions to provide alternative drinking water
supplies where there is an imminent human health threat.
6. The question of who should pay for corrective actions at sites con-
taminated by the approved use of a pesticide is a legislative
question. EPA believes that several aspects of the problem must be
considered before a decision can be made.
IMPLEMENTATION ISSUES
The final part of this document puts forth a number of implementation is-
sues and questions raised by the proposed pesticide strategy. The Agency is
particularly interested in receiving input on these issues before finalizing
its strategy and initiating the development of an implementation plan. To re-
flect the presentation of the pesticide strategy, this part of the document is
also arranged into three chapters covering the implementation issues
associated with the Agency's proposed policies for its environmental goal,
prevention strategy and response strategy.
Environmental Goal: The key implementation issues underlying EPA's goal are:
1. What definition and process should be used to identify ground waters
as potential drinking water sources that require baseline protection?
2. What definition and process should be used to identify "high priority
ground waters"?
Prevention Policy and Program: There are six key areas of implementation
issues raised by EPA's prevention policy and program:
6
PROPOSED STRATEGY
-------
1. Generic national control measures;
2. Barriers to implementing a differential approach;
3. State management plan - criteria, EPA oversight, and support.
4. Support of user decisionmaking;
5. Research and development priorities; and
6. Monitoring/early-warning system - mechanism and criteria.
Response Policy and Program: EPA identified the following four key
implementation issues arising from its proposed response program:
1. Under what circumstances should EPA consider not registering a pesti-
cide in a State that does not have a corrective action scheme?
2. What indirect EPA responses, including technical assistance to the
States or national public information and educational efforts, should
be a priority for development?
3. What can be done to facilitate coordination of enforcement activities
under FIFRA, RCRA, SDWA, and CERCLA to identify parties responsible
for contamination resulting from misuse, such as illegal disposal or
leaks and spills? and,
4. When should EPA consider assisting a state under the Agency's CERCLA
removal program? What should be the criteria for defining an imminent
health threat resulting from pesticide contamination of drinking
water?
7
PROPOSED STRATEGY
-------
PART I
PROBLEM ASSESSMENT SUMMARY
-------
PROBLEM ASSESSMENT SUMMARY
INTRODUCTION
The purpose of this first part of the document is to provide a brief
summary assessment of the pesticides in ground-water concern. This assessment
highlights the basic characteristic of the problem which EPA considered in
developing its proposed strategy. A more detailed description of the problem
can be found in the background documents and strategies listed in Table 1-1.
11
PROPOSED STRATEGY
-------
Table 1-1
Examples of Key Reports on the Ground Water Problem
and Recommended Strategies
1. Ground-Water Protection Strategy
U.S. Environmental Protection Agency
Office of Ground-Water Protection
(EPA, 1984)
2. Pesticides in Ground Water: A Background Document
U.S. Environmental Protection Agency
Office of Ground-Water Protection
(EPA, 1986)
3. Improved Protection of Water Resources from Long-Term
and Cumulative Pollution: Prevention of Ground Water
Contamination in the U.S.
U.S. Environmental Protection Agency
Office of Ground-Water Protection
(EPA, 1987) (Prepared for OECD)
4. Protecting the Nation's Groundwater from Contamination
Office of Technology Assessment
U.S. Congress
(Washington, D.C., 1984)
5. Ground-Water Quality Protection: State and Local Strategies
National Research Council
Washington, D.C., 1986)
6. Agricultural Effects on Groundwater Quality
Congressional Research Service
U.S. Congress
(Washington, D.C., 1986)
7. A Congressional Agenda to Prevent Groundwater Contamination:
Building Capacity to Meet Protection Needs
Environmental and Energy Study Institute
(Washington, D.C., 1986)
8. Groundwater Protection: Saving the Unseen Resource
The Conservation Foundation
(Washington, D.C., 1987)
9. The Leaching Fields: A Nonpoint Threat to Groundwater
California Assembly Office of Research
(California, 1985)
10. Groundwater Contamination in the U.S.
Pye, Patrick, et al
(Philadelphia, 1983)
12
PROPOSED STRATEGY
-------
CHAPTER 1
GROUND WATER: THE RESOURCE
1. Use and Value of Ground Hater
Ground water is a critical national resource which provides about
one-fourth of all the water used in the United States. It is the source of
drinking water for nearly half of the total United States population, and in
rural areas ground water may be the only, or at least the dominant, source of
drinking water. In eight states, 90% or more of the entire state population
depends on ground water for their domestic water supply (Table 1-2).
By volume, irrigation consumes the largest amount of ground water,
accounting for about two-thirds of ground-water withdrawals in 1975. As shown
in Figure 1-1, withdrawals of ground water nearly tripled between 1950 and
1980, reaching 88 billion gallons per day in 1980. In addition to meeting the
nation's demand for water, ground water plays an important environmental
function. For example, ground water provides recharge to surface streams and
sustains aquatic wetlands and terrestrial ecosystems. In coastal areas,
ground water helps prevent saltwater intrusion into potable water supplies.
2. The Nature of Ground Water
Ground water is found within the earth in geological formations called
aquifers (Figure 1-2). Vertical geological profiles of ground-water systems
are divided into different zones. The uppermost zone is called the
unsaturated zone, and by definition does not contain enough water to enable a
well drilled into this zone to yield usable quantities. The properties of the
unsaturated zone, however, control the extent of recharge of water from the
land surface to the saturated zones below. The extent of recharge to an
aquifer can be thought of as a balance between infiltration or percolation of
water down through the unsaturated zone and horizontal runoff on the land
surface, or return of moisture to the atmosphere by evapotranspiration. The
properties of the land surface and unsaturated zone material that control
recharge include the slope, extent of vegetation cover, thickness of the
13
PROPOSED STRATEGY
-------
-Ci
CA
CJ
PťN
*-*
O)
Ł
o
Q
j^
o
fc^
.
-4-*
03
*>^
J^^
T3
C
[3
O
O
O
DC
c
'-f1
Percentages Of People R
"3 o
^*cS
kf CO Q
(D O
Q. 0-
(O
**
to
CO
Z
0
CD
v_
1
-
.
m
co" '
co
0
CO
CO
CO
.0 .
(D
"5.
>^
.=-
CO
.12
CO
rizona, Florida, Hawaii, Idaho, Mi
New Mexico
<
o
00
1
o
00
.
B
-
"
.
*
"
m
co
41
o
co
Q
.c
D
o
CO
O
\
O
.
m
-
"
_
"
.
m
CD
'co
co"
1
2?
co
I
E. o"
- 0
^ if
3 2
1 1
* 0.
o" -o"
T3 C
CO JO
O ^
o to
O ^
CO
^
2
0)
c
5
[o
co
TJ
co
o
^
Ť
CO
Ł
_c
CO
CD
co
4-ť . .
wtr
S Q-
Q)
^3
CD co
§5
U- i^_
*-^
Ł =
CO Ł
^ o
- 1
S^
"2
Q.
Ł o
o Ž
IS
tr co
3^
f"-2
||
.28
"o o
li
tl
Q.E
*- "~
o^
U-l-
0
o
z
i
^
CJ
i
-
pS
UJ
cf
.0
t3
p
Q:
a
^
^
Ground
H~.
O
5
o
of
.9?
e: State Ground Water Program Summar*
^
CA
14
PROPOSED STRATEGY
-------
3
C/5
1
2
TJ
ft
"O
C
o>
TO
0)
.0
I
I
.s
I
CD
* ť E E is
Ť 255°
^ 2 = "m ť-
2
D
Ł OQ 6 Ł
c Ł
1 i
O
I
CQ
1
8
-------
E
o>
2
a
o>
o
c
2
16
PROPOSED STRATEGY
-------
unsaturated zone, the inherent capabilities of the unsaturated zone materials
to conduct water, and the presence of cracks or fractures in the zone.
The saturated zone is the aquifer. It is the geological zone from which
water may be obtained by pumping. Often there may be several aquifers in a
geological profile (Figure 1-2), separated by layers of less permeable rock
and clay. The boundary between the unsaturated zone and the uppermost aquifer
is called the water table; the water in this area is an unconfined, or water
table aquifer. Surface water can enter such an aquifer through percolation.
The lower aquifer in Figure 1-2 is a confined aquifer; the entry point or
recharge zone for water to reach this aquifer may be far away from the point
of withdrawal. Even when aquifers appear to be separated from one another as
shown in Figure 1-2, they may be connected through interruptions or fractures
in the intervening layers.
The characteristics of aquifers can vary greatly in area, depth below the
land surface, volume of water stored, permeability, interconnectedness, and
velocity of flow. Some aquifers underlie only small local areas, while others
span thousands of square miles and cross several State boundaries. Usable
aquifers are found almost everywhere in the United States (Figure 1-3). Water
is recharged to, or enters, aquifers by percolation from rainfall, snow-melt
and runoff, or has been trapped in aquifers since geologic time. Many
aquifers may also have natural discharge areas, such as springs, marshes, or
stream-beds. It has been estimated that about 30% of the flows in streams and
rivers during an average year is provided by ground-water discharge.
The rate of ground-water movement through an aquifer depends largely on
the permeability of the aquifer. In a uniform aquifer, the velocity of the
ground-water movement may range from 1 meter/year to 1,000 m/yr, with the most
common rate being between 10-100m/yr. Slow rates of movement can prevent
contaminants from spreading or mixing rapidly, concentrating them in
slow-moving plumes that may remain undetected for long periods of time. Such
time lags could result in contamination being found long after the source of
contamination has been effectively removed.
17
PROPOSED STRATEGY
-------
CO
Ł
DC
O
X
1-
>
o
CO
QC
LU
LL
5
o
LU
H
O
D
O
O
QC
0.
CO
LU
h-
<
H-
CO
Q
LU
h-
Z
ID
LU
I
1-
Z
CO
_J
LU
5
0
cc
LL
~ 18
PROPOSED STRATEGY
-------
An aquifer's permeability is determined largely by the types of solid
materials or geological formation of the aquifer. In some areas, the aquifer
may consist of fine sand or include significant amounts of silt and clay and
thus have a much lower permeability.
19
PROPOSED STRATEGY
-------
CHAPTER 2
PESTICIDES IN GROUND WATER: THE CONCERN
1. Extent of Contamination
Until a few years ago, most people believed that ground water was
protected from contamination by soil and rock formations. This general belief
began to change in the late 1970's with the findings of chemicals in a number
of wells across the country. In 1979, two pesticides were discovered in
ground water: dibromochloropropane (DBCP) in California and aldicarb in New
York. Additional monitoring in other States shortly thereafter showed DBCP in
ground water in Arizona, Hawaii, Maryland, and South Carolina; and aldicarb
was found in Wisconsin in 1980.
Perhaps the most serious case of pesticide contamination of ground water
was the discovery in 1982 of ethylene dibromide (EDB) in two California wells
and in three wells in Georgia. By the end of 1983, EDB contamination of
ground water had been discovered in 16 different counties in California,
Florida, Georgia, and Hawaii. These findings caused EPA to issue an immediate
suspension of all EDB soil uses in September 1983.
Until the discovery of pesticides in ground water, Federal and State
agencies did not monitor ground water for these chemicals. There were several
reasons: most ground-water monitoring until that time focused on urban rather
than rural agricultural areas; analyses of water were usually for volatile
organic contaminants, while most pesticides have low volatility; and reports
of positive findings of organic contaminants did not always distinguish
between surface and ground-water systems.
The discovery of DBCP, aldicarb, and EDB in certain areas of the country
stimulated a number of monitoring activities by Federal and State agencies to
investigate the extent of the problem. By 1986, a total of 19 different
pesticides had been detected in ground water in 24 States where the source of
the contaminant was most probably a result of agricultural application
(nonpoint source) rather than from spills or other point sources of the
21
PROPOSED STRATEGY
-------
pesticides (Table 1-3 and Figure 1-4). It is important to note that ground-
water contamination resulting from normal pesticide use applications may occur
over large geographical areas and result in exposure to large segments of the
population.
Some of the more important findings from recent State monitoring efforts
are as follows:
t California; Approximately 57 different pesticides have been detected
in California's ground waters; one-half of these were attributed to
point sources (leaks and spills) rather than normal pesticide
application. Nearly 2500 drinking water wells were found to contain
DBCP; about 60% of these had levels above the State standard of 1
part per billion (ppb). About 700,000 people may have been exposed
to DBCP via drinking water as a result.
t Hawaii; Thirteen public drinking water wells have been found to be
contaminated by EDB, DBCP, and/or trichloropropane; these wells serve
more than 130,000 people.
Florida; EDB has been found in about 10% of public and private
drinking water wells serving more than 50,000 people. About 1,200
wells have been closed.
New York; On Long Island, almost 2,000 wells were found to contain
aldicarb; about 50% of these wells had levels which were above the
New York State standard of 7 ppb.
Minnesota; Separate surveys of private and public drinking water
wells have been conducted recently. In 1986, one or more pesticides
were detected in 52% of 225 private wells; and in an ongoing survey
of public wells, one or more pesticides have been detected in 29% of
366 wells sampled. The average concentrations of pesticides found in
these wells were below the State health standards.
Iowa; Nine herbicides and two insecticides have been detected in
monitoring studies conducted in Iowa. For the most part,
concentrations were less than one part per billion; the major source
of these pesticides were attributed to normal agricultural
application. Monitoring data indicate that about 27% of the
population consumes drinking water which contains low concentrations
of pesticides.
While all of the above State surveys have expanded our knowledge of
pesticide contamination of ground water, they cannot be assembled into a valid
national estimate of the extent of ground-water contamination. Many of these
State surveys have been conducted in areas where contamination was already
22
PROPOSED STRATEGY
-------
-d
y g
Ł o-R
H OH S
00
CO
(N
0
VH
* ť
^>- 5
00
g
o
1-1
o
h 1
g
O
HH jt
s 1
'o
to
Ł
g
D
P
C/3
a
O Q CM
*-o Ť o^- ,
,55 , in ,
- ' CO g 'r,S
O T- O CO i- O O
z
** c S* ^
1 1 r ^ ^ ~" > . i p z ~~^
z ^ . . 2 ^S"'"
, o -g ' = ii
-------
S
s
o
.S 2
-2 2
S3
o .a
us
CU
o>
-D
S
s
3
K
PROPOSED STRATEGY
-------
known to exist and have been conducted for different purposes and according to
different design strategies. In order to get a better handle on the extent of
the problem, EPA has initiated a comprehensive statistically based survey of
drinking water wells across the country. Results from this survey are
expected to be available in 1989.
2. Potential Health Effects
The health effects of chemicals can be divided generally into two classes:
acute effects and chronic effects. Acute effects result from contact with
high levels of a chemical over a short period of time; chronic effects
generally occur as a result of long-term exposure to low levels of a chemical.
Acute effects, such as nausea, skin irritation, etc., are usually easier to
identify because they occur soon after exposure. Chronic effects, on the
other hand, are harder to document, particularly because of the long time
interval between exposure and outcome.
Generally, concentrations of pesticides in ground water have been found at
low levels, and therefore most of the concern has been focused on the
potential for chronic effects, such as cancer, mutations, birth defects, and
immunological changes. However, there are many gaps in our information about
chronic effects of pesticides in ground water. Although the toxicity and
general chronic effects for certain pesticides may be known, it is difficult
to associate a health problem due to exposure to the chemicals in drinking
water. Assessing the risk posed by a pesticide in ground water involves
knowing the precise combination of hazard and the duration and intensity of
exposure. Furthermore, the risk can be complicated by a combination of
several factors such as degradation processes, routes of exposure, and the
effects of other chemicals in the ground water.
Health risk assessments are a fundamental tool used by EPA programs to
characterize the potential for harm to human health by chemical substances in
the environment. These assessments form a key part of the basis upon which
policy makers determine whether, and to what extent, measures to reduce risks
are warranted.
25
PROPOSED STRATEGY
-------
EPA's method of risk assessment for potential ground-water contaminants is
based on a four-part process which includes: (1) hazard identification, (2)
dose-response evaluation, (3) human exposure evaluation and (4) risk
characterization. With respect to pesticides in ground water, EPA carries out
several risk assessment activities. One of the Agency's more recent risk
assessment activities has been the development of health advisories (HA's) for
60 known or potential leaching pesticides. These health advisories describe
the concentrations of contaminants in drinking water at which adverse effects
are expected to occur. In the near future, the Agency expects to develop
enforceable standards or maximum contaminant levels (MCLs) for pesticides in
drinking water.
3. Costs of Contamination
Measuring the costs to society from chemicals in ground water is a
difficult task. Some economists have estimated the costs and benefits of
ground-water contamination policies using a "damages avoided" framework on a
site-by-site basis. However, this approach has certain limitations, namely
that it may not be applicable to a national analysis. Another way to estimate
what society must pay to reduce a contamination risk is to appraise the
avoidance costs. A USDA report by Nielson and Lee, 1987, employed this
approach. In this report, the authors estimated that the costs of avoiding
risks imposed by ground-water contamination by pesticides are potentially
significant. Monitoring costs were the major expense for households, ranging
from $0.9 to $2.2 billion, with $1.4 billion being the "best" estimate.
The other major expense for households seeking to avoid risks from
pesticides in their drinking water was the cost of responding to
contamination. Installing home-water treatment units or providing alternative
drinking water supplies are possible options, but the costs can vary
significantly, depending on the system used and the size and location of the
area covered. Although national estimates are not possible to develop, data
do suggest that these types of actions could result in substantial costs,
particularly to small communities and private well owners.
26
PROPOSED STRATEGY
-------
Another option for responding to pesticide contamination of ground water
is to clean up or contain a contaminated aquifer. Containment or clean-up
techniques are much more expensive than the previous options and may be
economically feasible only for point source contamination, e.g., leaks and
spills. Cleaning up widespread nonpoint sources of contamination from
pesticide application would be even more expensive and may not be
technologically or economically feasible for most areas. The estimated cost
of cleaning up a hazardous waste site that involves ground-water pumping and
installation of a cutoff wall ranges from $1.9 million to $6.1 million,
depending on the volume of ground water pumped.
In addition to these direct costs associated with preventing and
responding to contamination of ground water, there are a number of other
indirect costs that society may face. For example, ground-water contamination
could result in crop loss and a decline in property values as well as
increased medical costs and the costs of possible law suits.
Because of these problems associated with the potential high costs and
technical complexity of responding to ground-water contamination by
pesticides, there is clearly a role for effective Federal and State management
strategies to prevent contamination.
27
PROPOSED STRATEGY
-------
CHAPTER 3
PESTICIDES IN GROUND WATER: CAUSATIVE FACTORS
An effective prevention strategy must consider the complex set of factors
which determine the likelihood of a pesticide reaching ground water. The
factors and their interactions vary greatly depending on specific local
conditions and circumstances. For this reason, the problem of pesticides in
ground water, although a national concern, must be addressed at a more
localized level. The following discussion outlines the set of factors which
affects ground-water contamination. These factors have been grouped into four
major areas: sources of contamination, chemical-physical characteristics of
the pesticide, ground-water vulnerability and agricultural practices.
1. Sources
Ground water may become contaminated by pesticides at any point in their
use cycle (Table 1-4): during manufacture, distribution in commerce, storage,
use on the land or in industrial settings, or disposal. These sources of
potential contamination may be grouped together into two categories based on
the characteristic of the contamination potential and on the types of actions
that may be taken to prevent contamination.
The first category includes accidental spills and leaks of pesticides at
manufacturing facilities or distribution points such as agricultural chemical
dealerships or commercial applicator facilities, where bulk chemicals are
stored and handled. Also included in this category are places, including
hazardous and municipal waste landfills and other waste handling or treatment
facilities, where chemical wastes are disposed of. Ground-water contamination
resulting from leaks and spills generally result in plumes that are relatively
localized. The origin of such "point source" contamination may be prevented,
and clean-up using available techniques may be possible.
The much larger second category of sources is application of pesticides to
crops, rangeland, forests and rights-of-way. When pesticides are applied to
the land, they are carried above, across, and through the ground by wind,
29
PROPOSED STRATEGY
-------
2
^
5j
j-
O)
'S
c
o
O
'o
c
0
'-§
c
a
OB
-*-
C
O
^
3
tŤ
Ł
*o
Cfl
0
u
3
O
C/3
is
'S
OH
O
"§Ť
CO-
-*"a.
a.
~n
||
a-3
75
O
2 w
%M '^3
^^ {u
to^
"3 ^
c o
^LL.
ŤŁ
XXXX XXXXXX
XXXX X XXX
XXXX XX
XXXX X XXX
^_
a>
CO 5
Jii V) O
w ^ S
^J ^C ^~ O ""} ^ ^> 2tZ ^ 73 k- ^J
Z *1> "ia, o JŤi^.f5fl>Ž n 2* 5
< Q) §>:= .CD. <ŤQ.cS'ci>-s 52 O- Ł ^
/A CO CO 5r ^3 ^ ^^ f^ ^ ?Q CJ ^* CO ^( ^3 s*^
coco _j h- (/) a. OC_IOQ
W Q _J
XXX
to
5
"c w
CO S
CO CO
75 en
^ (Z
^ T3 ._
0 CO J2
2 o o
= ^ -1
1 C -0
C "x
5 1 Ł
30
PROPOSED STRATEGY
-------
rainfall, runoff, and infiltration. Pesticides dissolved in runoff water are
carried to nearby surface water or may enter ground water through direct
infiltration at the point of application or after traveling via the surface or
through soil to ditches or other runoff retention areas. They may also reach
ground water through sinkholes or poorly constructed well casings or abandoned
wells.
Of the 1.1 billion pounds of pesticide chemicals used in 1984, 77% or 861
million pounds were used in agriculture, with the rest used by industry,
government, and home and garden users. There are about 600 actual pesticide
chemicals in common use, and these are formulated into over 45,000 individual
products. Important types of pesticides include insecticides, herbicides,
fungicides, plant growth regulators and rodenticides. Herbicides form the
largest use class, as shown in Table 1-5. They are also the most rapidly
growing class (Figure 1-5): applications of herbicides now account for nearly
90% of the acreage of all major crops treated. For pesticides as a whole, six
crops (alfalfa, corn, cotton, sorghum, soybeans, and wheat) account for about
90% of all acre-treatments. This concentration of pesticide use on a few
major crops means that the application is heavily concentrated in certain
major agricultural areas, such as the upper Midwest of the U.S.
2. Physical-Chemical Properties
Not all pesticides are equal in their ability to reach ground water. Just
as there are great variations in the natural vulnerability of ground water to
contamination, there are great variations in the chemical properties of
pesticides which control their tendency to leach to ground water. Although
ground-water contamination by pesticides is a relatively recent public
concern, research on the environmental fate of pesticides in soil over the
last two decades has provided a general understanding of the pesticide
properties and environmental conditions which together determine the potential
for a pesticide to reach ground water.
31
PROPOSED STRATEGY
-------
L-
O
-4^
U
a>
cť
T3
c
CQ
CA
en
CQ
U
a>
CA
^_^
Is
.-
3
cv
s*
DJD
G
0>
*PN
t3
CS
"o
05
o
c
o
a
Ť**
o
c
o
3
*fi
^
Ť
o
I-
>_
a>
JC
4-i
0
m
(0
a>
o
u
0)
c
LJ_
C^
(0
0)
T3
7;
"o
O
(0
T 1
(0
a>
T3
"o
!Q
X
0
i-5
CXI
o
*o
V)
8
tf)
$
I
"3
"C
CJD
i-( i-l
SO >^
i-H
i-H i-^
fS rH
O ťŤ
<ť CO
ť/i O
1-1 CO
^ fi
o a>
o -g
~ Ť
s o
s ^
o ^*
U Ť
1 1
c '5
o °
X CQ
"= S
S? 8
O co
Ł *O
D "o
"O '*3
3 C
O Ť
u s
co co
CJ O
*o *o
"o o
s c
O co
CŁ
^ a)
OOQO
Ł Q
(N CO
32
PROPOSED STRATEGY
-------
en
Ł
a
a>
toO CJ
cT '+
WH ^^
[2
e
CO
oo
oo
oo
ts
oo
CO
I
o
c
I
I
VO
o\
8
4**
cs
B
I
I
o
o
o
o
o
o
o
00
o
o
o
o
o
o
cs
o
o
CO
1
B
O
4> CM
T3 CO
3 O)
O ^
x -a
uj a
tn
33
PROPOSED STRATEGY
-------
No single property of a pesticide chemical uniquely determines its
potential to leach; rather, the interaction of several independent properties
governs leaching behavior. Tests for these properties are required for
registration of all pesticides used on crops. The properties include:
water solubility: the propensity for a pesticide to dissolve in
water. Pesticides with water solubility can more easily be carried
in solution in water percolating down to the water table. Solubility
of greater than about 30 parts per million has been selected as a
"flag," indicating a pesticide with a high potential to leach (Cohen
et al, 1983).
t hydrolysis: the rate of degradation of a pesticide in water when no
other process is taking place. This rate is particularly important
because after a pesticide has leached below the soil zone of active
biological activity, hydrolysis is essentially the only process
available to decompose a pesticide. The time for hydrolysis to
destroy half the amount of a pesticide present in solution is called
the hydrolysis half-life; a value greater than about 6 months
indicates chemicals with high potential to reach ground water.
soil adsorption; the propensity of a chemical to bind to soil,
defined as the ratio of concentration in soil to concentration in
water at equilibrium. This ratio is denoted as Kd. A second measure,
Koc, is a similar ratio based on the organic matter content of the
soil, since organic matter is most active in binding chemicals
present in soil. Pesticides with low values of Kd and Koc bind less
strongly to soil and are therefore more likely to leach. Most of the
pesticides found in ground water have Kd values less than about 5
(often less than 1); the corresponding Koc values are less than 300.
soil degradation; a simplified measure of pesticide persistence in
soil, usually measured as the time required for disappearance of
one-half of the residue present. This time is called the half-life
of the pesticide, and measures degradation by both chemical and
biological processes in soil. Soil half-lives are measured by field
experiments required for registration of pesticides; half-lives
greater than about three weeks indicate soil persistence sufficient
to allow high potential for leaching.
The downward movement of a pesticide is essentially driven by competition
between the processes of degradation and leaching. A pesticide which degrades
rapidly in surface soil (or which is efficiently taken up by plant roots) is
unlikely to survive long enough to move downward under the influence of
infiltrating water; and a pesticide which is tightly bound to soil will be
34
PROPOSED STRATEGY
-------
unlikely to move downward no matter how long it remains in the soil. The
combination of relative persistence in soil and lack of binding to the soil
are the two dominant characteristics of pesticides which have the potential to
leach to ground water.
3. Local Ground-Water Vulnerability
A number of factors determine the general vulnerability of local ground
water to contamination by pesticides. Local climatic conditions are one of
the most important determinants. Under this category, the amount of rainfall
affects the amount of water available for transporting pesticides through soil
to underlying ground water. Other key climatic conditions that affect
pesticide degradation processes and vulnerability to contamination are soil
and air temperatures.
The depth of the aquifer is another key determinant. If a pesticide has
to travel a great distance to reach an aquifer, it has a greater chance to be
diluted or degraded. A third key determinant of ground-water vulnerability is
the type of soil present at a pesticide application site. The properties of
the soil can vary greatly and depend on:
clay content; the amount of clay minerals in the soil. The clay
fraction provides cation exchange capacity to bind positively-charged
chemicals (cations). Clay soils also have a high surface area which
further contributes to adsorption capacity.
organic matter content: also contributes to adsorption of pesticides
to soil, particularly neutral species. In fact, pesticides which are
applied to soils high in organic matter will often be applied at
higher rates to compensate for this absorption.
soil texture; refers to the percent of sand, silt, and clay in soil.
Leaching is more rapid and deeper in course or light-textured soils
than in fine or heavy-textured clay soils.
soil structure: refers to the way soil grains are grouped together
into larger aggregates -- as plates, prisms, blocks, uniform grains.
Water and dissolved pesticides can percolate through cracks in soil
structures. Often large cracks or channels resulting from soil biota
are present, allowing rapid infiltration.
35
PROPOSED STRATEGY
-------
t porosity; a function of total pore space and pore size in soils.
Porosity is determined by soil texture, aggregation, and particle
shape. Water transport is more rapid in highly porous soils.
soil moisture; interstitial water in the soil matrix ultimately
dissolves and transports pesticides that are not adsorbed. Upward
movement may also occur through capillary action or by evapotrans-
piration, in which water in the soil is lost to the air.
All of these factors determining general ground-water vulnerability can be
assessed for any given site if data are available. Using these sets of
factors, the Natural Water Well Association developed a system (DRASTIC) for
assessing ground-water vulnerability. As an initial step in designing their
national pesticide survey, EPA used the DRASTIC system to evaluate the average
vulnerability of counties in the United States (See Figure 1-6). The major
drawback of this approach is that it does not account for the large
variability of ground-water vulnerability within a given county, as Figure 1-7
clearly demonstrates. Moreover, the presence of certain local features can
make a certain area more susceptible to ground-water contamination than an
average county-vulnerability score would indicate. These local features
include the presence of sink holes, fissures, mine shafts, abandoned and
uncapped wells, or poorly constructed and protected wells. Because of these
problems, EPA has not used county average DRASTIC scores as a basis for
pesticide regulation.
4. Agricultural Practices
The final group of factors affecting the potential for pesticides to
contaminate ground waters are local agricultural practices. Obviously such
practices will vary greatly across the country depending on the crops grown,
local pest control needs and the preferences of the grower. Key factors that
are part of the agricultural practices include:
application rates; how much pesticide is applied has a direct effect
on the amount of pesticide available for leaching.
t timing of application; when a pesticide is applied in relation to
rainfall events, season of the year, or presence of crop cover can be
a major factor.
36
PROPOSED STRATEGY
-------
C/3
O
*^
o>
*-ť
"5
p
C/3
-
o
^c
S-.
0>
+ť
o
U
I
2
SM
0>
4-ri
03
3S
'O
c
3
O
S-
O
I*
O
OJD
u
<
z
<
_l
Q.
X
UJ
CM
VI ^
LU o
DC *~
3 8 VI
^ CO
DC uj
< CC
> O
uj VI o
Al
DC
O CM
O o
CO T-
DC c
w re
T5 J3
CO i
w ^
I
8
CC
<
CO
(O
re
.a
CO
(0
re
.0
= ^ §
8 I §
= CO
S Ł
re 3
co >
-^ 5J
3 re
> |
.5> o
1
CO
37
PROPOSED STRATEGY
-------
Figure 1-7
Map of Ground Water
Pollution Potential
Portage County, Wisconsin
Prepared by: National Water Well Association
LEGEND
DRASTIC VARSCORE
Range
80-119
120- 179
> 179
Color
D
M
m
38
PROPOSED STRATEGY
-------
method of application; pesticides can be applied as foliar sprays to
standing crops or sprayed directly on bare soil, by dissolution in
irrigation water, or by direct injection beneath the soil surface.
Direct injection or soil incorporation of surface-applied pesticides
pose the highest potential for ground-water contamination.
cultivation practices; conservation tillage practices used to
decrease soil erosion can increase water infiltration and concomitant
leaching of soluble pesticides. These practices also often require
increased use of herbicides.
spillage and disposal; as discussed earlier, spills can result in
high concentrations of pesticides in soil which can overwhelm
decomposition and adsorption capabilities. Spillage can be a common
problem where pesticide mixing and loading activities take place.
Handling of empty containers and rinsate from cleaning spray
equipment may also result in high localized concentrations of
pesticides in soil.
irrigation; soils under irrigation are highly permeable, and the
amount of irrigation water commonly reaching subsurface soil is
estimated to be 20 - 40% of the applied water. Irrigation practices,
thus, have the potential to dissolve and increase the potential for
soluble pesticides to leach ground water.
chemigation; in this practice, pesticides are applied to the field by
addition to irrigated waters. When the water comes from a well,
decreases in water pressure can result in back-siphoning of the
chemicals down the well if check valves preventing reverse flow are
not installed.
For any specific location where pesticides are used, factors in the above
four areas determine the potential for ground-water contamination. Not only
is the combination of factors very complex, but they are also very specific to
each location and vary greatly across all agricultural regions. Technical
expertise is needed to evaluate these factors and their combinations, as well
as knowledge of the specific local conditions and circumstances.
39
PROPOSED STRATEGY
-------
CHAPTER 4
STATUTORY AUTHORITIES AND INSTITUTIONAL FRAMEWORK
A complex set of Federal, State, and local laws authorize a wide variety
of activities and programs that can be used to protect ground water from
pesticide contamination. Many of these laws were written before pesticide
contamination of ground water became a concern and subsequently have been
broadly interpreted and expanded to cover this issue. Moreover, these laws
sometimes provide conflicting direction regarding how the pesticides in
ground-water concern should be managed.
1. Federal Level
At the Federal level, the primary agencies which have jurisdiction over
pesticides in ground water are the U.S. Environmental Protection Agency (EPA),
the U.S. Department of Agriculture (USDA), and the U.S. Department of Interior
(DOI). The U.S. Geological Survey within DOI has the principal role for
gathering hydrogeologic information on, and assessing the quality of, the
nation's aquifers. Through a number of Federal-State cooperative programs,
USGS and cooperative States compile information for planning, developing and
managing the nation's water resources.
A second key player at the Federal level is the USDA. Through its
Extension Service, Soil Conservation Service, Agricultural Stabilization and
Conservation Service, and Agricultural Research Service, the USDA provides
technical assistance to individual landowners and a range of incentives that
can affect the way landowners choose to manage their land and water resources.
Ultimately, landowners make choices regarding pesticide use and agricultural
practices at their specific sites. Agencies, such as those found in USDA,
which advise landowners play a significant role in ensuring that landowners
make environmentally sound decisions.
41
PROPOSED STRATEGY
-------
The third critical player at the Federal level is EPA. This agency has
the lead responsibility for regulating pesticide use in the United States and
for protecting the quality of the nation's ground water. Within EPA, several
environmental statutes and programs address one or more discrete sources of
ground-water contamination (Figure 1-8).
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
authorizes the Agency to regulate the marketing and use of pesticides
in the United States. Before allowing a pesticide on the market, the
Office of Pesticide Programs weighs the risks of a pesticide against
its benefits. Manufacturers must submit extensive data to EPA,
including environmental fate data which will indicate the leaching
potential of a pesticide.
The Safe Drinking Water Act (SWDA) is designed to ensure that public
water systems provide water meeting minimum standards for protection
of public health. As required by the Act, EPA establishes drinking
water standards (Maximum Contaminant Levels) and water supply
monitoring requirements for public water supplies to meet.
Under recent amendments to the Act, the Agency has been authorized to
provide resources to States to establish "Wellhead Protection Areas"
(WHPA) for public drinking water wells. Other recent amendments
restrict underground injection of hazardous waste and establish a
sole source aquifer demonstration program.
0 Clean Water Act (CWA) The basic mission of the CWA is to restore and
maintain the chemical, physical, and biological integrity of the
nation's waters. EPA provides grants to States for development and
implementation of State ground-water protection strategies. Under
the CWA's nonpoint source authorities, EPA also provides financial
assistance to States for nonpoint source monitoring/assessments,
planning, program development, and demonstration projects.
t The Resource Conservation and Recovery Act (RCRA) regulates disposal
of waste, including pesticides, which may create a hazard. Pesti-
cide-containing wastes that are considered hazardous wastes under
RCRA are subject to extensive regulatory requirements governing
storage, transportation, treatment, and disposal.
The Comprehensive Environmental Response, Compensation and Recovery
Act (CERCLA)establishesatrust fund(Superfund)tofinance
government responses to releases or threats of releases of hazardous
substances. However, if ground-water contamination results from
normal application of pesticides, the law does not allow the Agency
to recover costs from pesticide applicators or private users.
42
PROPOSED STRATEGY
-------
I*
c->
13
C
9
O
oo
OX)
c
0)
43
PROPOSED STRATEGY
-------
2. State Level
States have traditionally been responsible for implementing and enforcing
Federal policies and standards. With the assistance of CWA grants,
practically all States are now developing and implementing ground-water
protection strategies addressing various sources of contamination, including
pesticides. While many States have at least some activities addressing
pesticide contamination, only a few have begun efforts that could be defined
as prevention programs. Several States have established or are developing
regulatory programs to require safety measures on chemigation systems and
requirements for pesticide mixing, loading, and storage areas.
A few States are preparing for or have passed legislation aimed at
protecting ground water from contamination. In addition, many States have
initiated ground-water monitoring programs and have identified areas where
pesticide contamination of ground water is a problem.
State efforts to address the pesticides in ground water concern have some
of the same coordination problems that the Federal government has. Often, the
agency responsible for pesticides control is housed in the State agricultural
department, while primary responsibility for water quality and waste disposal
programs is located in a State environmental protection agency.
Responsibility for ensuring safe drinking water often rests in still another
agency, such as a public health department. This fragmentation of
responsibilities among various agencies makes it difficult to establish an
effective Federal-State relationship.
3. Local Level
The United States has more than 91,000 units of local government which by
and large operate under State control. The local governments are the first
point of contact for controlling contamination of ground water. Through their
land use and zoning powers, local governments can also closely influence
ground-water use and quality.
44
PROPOSED STRATEGY
-------
In summary, protection of ground water from pesticide contamination will
require a coordinated approach among a number of agencies at each level of
government. Development of a national EPA strategy is one of the first steps
needed in moving toward an integrated and successful management approach.
45
PROPOSED STRATEGY
-------
CHAPTER 5
CONCLUSION
The significant findings of this problem assessment are as follows:
1. Ground water is a valuable national resource; however, its value and
use vary greatly across the country.
2. Ground water is vulnerable to contamination by normal use of
pesticides as well as from leaks, spills and improper disposal.
3. Although the exact extent of the problem of pesticides in ground
water is not known, enough information has been reported to indicate
that ground-water contamination has occurred in a number of cases
across the country.
4. While ground-water contamination by pesticides usually occurs at very
low levels, significant levels have been found in some areas and have
resulted in numerous well closings. Health and environmental risks
associated with pesticides in ground water are a function of toxicity
and exposure. The true magnitude of the problem is unclear at this
time and may not be known for several years.
5. Once widespread contamination of ground water by pesticides has
occurred, it will often be infeasible to clean up. Provisions of
alternative water supplies or adequate treatment may also be
impractical if contamination is widespread. For these reasons,
prevention of unacceptable contamination must be the focus of
protection efforts.
6. The potential for ground-water contamination by pesticides is
determined by a complex set of factors which vary considerably from
area to area. Understanding these factors is essential for designing
an effective prevention strategy.
47
PROPOSED STRATEGY
-------
7. The highly variable characteristics of the ground-water resource and
the site-specific nature of the ground-water problem demand a more
localized approach for managing protection efforts.
8. The number and complexity of Federal and State programs and statutory
authorities which may be used to address the pesticides in ground
water concern are substantial. Protection of ground water from
pesticide contamination will require a coordinated approach among
Federal agencies and with the States.
48
PROPOSED STRATEGY
-------
BIBLIOGRAPHY
The following references were consulted in preparing this Problem
Assessment:
Cohen, S.Z., S.M. Creeger, R.F. Carsel, and C.G. Enfield, Potential Pesticide
Contamination of Groundwater from Agricultural Uses (American Chemical Society
Symposium Series No. 259, 1984)
The Conservation Foundation, Groundwater; Saving the Unseen Resource and A
Guide to Groundwater Pollution: Problems, Causes, and Government Responses,
(Washington DC 1987)
Freeze, R.A., and J.A. Cherry, Groundwater (Prentice-Hall, Inc., Englewood
Cliffs, NJ. 1979)
Office of Technology Assessment, US Congress, Protecting the Nation's
Groundwater from Contamination (Washington DC, 1984)
Neil sen, Elizabeth G. and Linda K. Lee, The Magnitude and Costs of Groundwater
Contamination from Agricultural Chemicals (USDA, 1987).
Pye, V.I., R. Patrick, and J. Quarles, Groundwater Contamination in the United
States (University of Pennsylvania Press, Philadelphia, 1983)
US Environmental Protection Agency, Office of Research and Development,
DRASTIC; A Standardized System for Evaluating Ground-Water Pollution Potential
Using Hydrogeological Settings (EPA, 1985)
US Environmental Protection Agency, Office of Ground-Water Protection,
Pesticides in Ground Water; A Background Document (EPA, 1986)
US Environmental Protection Agency, Office of Ground-Water Protection,
Improved Protection of Water Resources from Long-Term and Cumulative
Pollution; Prevention of Ground-Water Contamination in the United States (EPA,
1987}
US Geological Survey, National Water Supply Summary 1984 (USGS Water Supply
Paper 2275, US Government Printing Office, 1985)
49
PROPOSED STRATEGY
-------
PART II
PROPOSED PESTICIDE STRATEGY
-------
PART II
PROPOSED PESTICIDE STRATEGY
The purpose of this second part of the document is to present EPA's
proposed strategy for addressing the pesticides in ground water concern. The
presentation of the proposed strategy is divided into three chapters (Figure
II-l):
Environmental Goal
Prevention Policy and Program
Response Policy and Program
In the first chapter, the Agency defines its environmental goal in terms of
what waters to protect and the criteria for determining protection. The
resolution of these issues is a prerequisite for establishing policies for both
prevention and response efforts.
The second chapter presents the Agency's strategy for preventing
contamination and focuses on the key issues of how to address local variability
and the appropriate Federal/State roles and responsibilities in managing the
problem. In defining its prevention policy and program, the Agency has examined
options available, not only under its basic pesticide law, but also under other
environmental authorities and the authorities of other Federal agencies as well
as State capabilities.
The final chapter of the pesticide strategy establishes the overall
framework for responding to ground-water contamination that has already
occurred. Here again the critical question is the appropriate Federal and
State roles and responsibilities.
For each of these chapters, the document will first highlight the options
and the factors which the Agency considered in formulating its strategic
approach. The second section of each chapter will present EPA's proposed
approach and specific positions on a number of key issues.
53
PROPOSED STRATEGY
-------
DD
&
IS
L*
5?
-SP
54
PROPOSED STRATEGY
-------
The policies presented in these three chapters form EPA's proposed strategy
for dealing with pesticides in ground water. It is important to note that a
number of key implementation issues are associated with this strategic
approach. These issues are summarized in the final part of this document. The
next major step in the planning process (Figure II-2) is to seek extensive
input on these particular issues from State agencies, other Federal agencies,
and other parties who will have key roles in the successful implementation of
this strategy. After receiving public input on the proposed strategy and
implementation issues, EPA will develop a detailed implementation plan the
final step in the process.
55
PROPOSED STRATEGY
-------
OD ~
&
.2
*^M
C3 '^>
^_> <*)
a c Ť
O) C3 3
Sr- en
^ PH Ťo
or
C*
%
1/5
Detai
orities
5
o
S,
00
Support Mec
-------
Pesticide Strategy
PREVENTION
PROGRAM
RESPONSE
PROGRAM
57
PROPOSED STRATEGY
-------
CHAPTER 1
ENVIRONMENTAL GOAL
EPA's proposed environmental goal will be to manage the use of pesticides
in order to protect the ground-water resource. The Agency will give specific
attention to preventing unacceptable contamination of current and potential
drinking water supplies. MCLs or other EPA-designated criteria will be used as
reference points for helping to define unacceptable contamination. This
environmental goal will be used as a benchmark to:
t Identify and evaluate if, and where, the problem exists;
Establish priorities to focus both prevention and response efforts;
t Select the most appropriate control measures; and
Assess progress in preventing the problem or responding to existing
threats.
Below is a discussion of the options and factors which the Agency
considered in developing its goal for the pesticides in ground water strategy.
Following this section is a presentation of the Agency's proposed position on
the key issues underlying the environmental goal.
SECTION 1; FACTORS AND OPTIONS CONSIDERED
The two key questions which the Agency has addressed in defining its
environmental goal for pesticides in ground water are: (1) what waters to
protect and (2) what criteria determine protection (Figure II-3). The Agency
has addressed these questions within the context of its regulatory statutes
and other Agency policies, including its basic policies for pesticide
registration.
In 1984, EPA issued the EPA Ground-Water Protection Strategy (GWPS) after
many years of internal debate and external review and comment. The Strategy
sets out goals and objectives for the Agency's ground-water protection
efforts. In the GWPS, EPA established the policy of protecting the
59
PROPOSED STRATEGY
-------
60
PROPOSED STRATEGY
a
o
TJ
O
-------
ground-water resource to ensure its quality for the highest present or
potential beneficial use. The highest beneficial use is defined as drinking
water.
The GWPS also developed a general policy for classifying ground waters
based on their use, value, and vulnerability. Dividing ground water into
three classes, this policy provides an extra degree of protection to ground
water that is highly vulnerable to contamination and is of great value because
of its importance as a source of drinking water or its contribution to a
unique ecological habitat (Class I). The majority of the nation's ground
water is in Class II, a current or potential source of drinking water, and it
is for this ground water that certain EPA ground-water protection requirements
are designed. Class III ground water is not a potential source of drinking
water because of levels of contamination from naturally occurring conditions
or the effects of broad-scale human activity.
The strategy proposed in this document affirms the intended extension of
EPA's basic ground-water policies to the Agency's efforts to protect ground
water from pesticide contamination. A number of policy issues and options,
already addressed under the GWPS, are presented here with options primarily
for those who may not be familiar with the Agency's basic ground-water
policies.
In developing the strategic approach for pesticides in ground water, EPA
considered several aspects of this overall Agency policy for ground-water
protection to determine the extent to which they were appropriate for the
pesticides effort. Alternative approaches, such as approaches that would
focus only on ground water currently supplying a drinking water well or that
would solely rely on treatment at the tap as the means for protecting public
health, were rejected as inadequate for protecting the ground-water resource
for present and future generations. The Agency concluded that while the
unique needs of agriculture must be accommodated in the strategic approach for
pesticides, the basic policy of protecting the ground-water resource itself
and focusing efforts on current and potential sources of drinking water would
be the appropriate framework. The differential approach in the EPA
Ground-Water Protection Strategy allows management strategies to be tailored
61
PROPOSED STRATEGY
-------
to ground waters of varying use, value, and vulnerability, but aims at
adequate protection for all ground water that is a current or potential
drinking water supply.
The following discussion outlines the factors and options which EPA
considered in determining its environmental goal for addressing the pesticides
in ground water concern.
1. What waters to Protect
Ground waters vary greatly in how they are used and in their value to
society. For example, in some areas, ground water may provide an irreplace-
able source of drinking water to a large population, while in other areas,
ground water may not be usable as a drinking water source because of its high
salinity or its low yield. Other ground water, that may or may not be a
drinking water source, could be valued for its importance to an area's fragile
ecosystems.
The first issue in determining what waters to protect is whether
protection efforts should be focused on assuring the quality of the ground-
water resource or the quality of water actually delivered to the tap for
drinking (Figure II-4). The difference between these two options is that the
latter choice could allow for the contamination of ground water in areas where
there is adequate treatment capability for reducing contamination to
acceptable levels before it is provided for drinking.
A second key decision for the Agency is to determine whether to spread its
protection efforts widely to protect all ground waters or to narrow its
protection focus on some selected waters that provide more valuable use. If
the Agency focuses its efforts on assuring that safe drinking water is
provided, it would have to decide whether to protect private wells to the same
extent as public water systems. If the Agency chooses to protect water in the
ground, then the Agency has a number of options, based upon the different
degrees of use and value of ground water (see Figure II-5), including:
62
PROPOSED STRATEGY
-------
t-H
-------
a
o
i-H
-4 >
O
o
UH
OH
S-H
.O
64
PROPOSED STRATEGY
-------
Protection for All Ground Water - One option is to protect all ground
water as it exists in the saturated zone regardless of its current or
potential use as a drinking water source. (As seen in Figure 11-6,
the saturated zone lies below the unsaturated zone, which is the first
zone of water and soil below the surface layer).
Protection for All Ground-Water Resources That Are Current or
Potential Drinking Water Sources or of Ecological Importance - This
option would also protect the ground water in the saturated zone, but
would limit protection to those ground-water resources that are
currently or potentially available for drinking water. A key consid-
eration in implementing this option would be defining potential
drinking water.
Protection for Only that Ground Water Currently Used as a Drinking
Water Source - This option would limit protection to those ground-
water resources that currently supply drinking water. A key
implementation issue would be defining what ground water actually
supplies a drinking water well.
Protection for Only that Ground Water Supplying Public Drinking Water
Systems - This option is similar to the previous one except that
protection is limited to those ground waters that supply public water
systems. Again, a key implementation issue would be deciding what
ground water actually supplies these drinking water wells.
Differential Ground-Water Protection - With this option, all ground
waters would be considered for protection, but priorities and
stringency of prevention and response efforts would be based on the
relative use and value of the ground water. For example, basic
protection efforts could be provided for ground waters that are a
current source of drinking water. Higher degrees of protection could
be provided to ground waters that serve large populations. On a
case-by-case basis, some ground waters that are not a drinking water
source could be afforded less protection where conditions warranted
such actions.
With regard to what waters to protect, EPA's legislative priorities
provide somewhat different direction. The major relevant EPA statutes which
address this question include:
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) - The
basic pesticide law, FIFRA does not specifically identify ground water
as an environmental medium requiring protection. However, EPA
recognizes that the public may be exposed to pesticides in drinking
water as a result of contaminated ground water, and thus, the ground-
water medium is included in EPA's interpretation of FIFRA1s general
requirement for protection of the environment. In addition, several
recently proposed bills to amend FIFRA would mandate a differential
protection approach requiring special protective measures for ground
waters that are a current or potential source of drinking water.
65
PROPOSED STRATEGY
-------
.
S
5/3
c
o
66
PROPOSED STRATEGY
-------
Safe Drinking Water Act (SDWA) - Federally-enforceable drinking water
standards under the SDWA are limited to the drinking water that is
provided by public water systems, i.e., those systems having at least
15 service connections or serving at least 25 persons daily. If the
question of what waters to protect is limited to those waters covered
by these SDWA drinking water standards, then individual private wells,
which are often found in rural areas and are most at risk from
pesticide contamination, would be excluded. (Note - some States do
take action for private wells based on SDWA drinking water standards.)
Another important factor to consider is that these SDWA drinking water
standards, which apply to public water systems, do not apply to the
ambient or raw water used by these systems unless it is provided
directly to the public. The public system can treat or blend its
water, however, to meet SDWA drinking water standards before
delivering it to the user.
The 1986 amendments to the SDWA established the Wellhead Protection
Program which, unlike previous SDWA measures, is designed to protect
ambient ground waters, but the focus remains on public water systems
and has no Federally-enforceable quality standards.
Clean Water Act (CWA) - As amended by the Water Quality Act of 1987
(WQA), theCWA does not differentiate ground water in terms of its
protection goal of restoring and maintaining the integrity of the
Nation's waters.
Resource Conservation and Recovery Act (RCRA) - As amended by the
Hazardous and Solid Waste Amendment of 1984 (HWSA), RCRA identifies
ground water as a specific medium for protection and requires ground-
water monitoring at hazardous waste facilities.
Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA or "Superfund") - As amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), CERCLA establishes criteria for
determining response priorities among releases or threatened releases
of hazardous substances. The potential for a release to contaminate a
drinking water supply is a major CERCLA criterion. Under CERCLA, a
drinking water supply is defined as being "any raw or finished water
source that is or may be used by a public water system (as defined by
SDWA) or as drinking water by one or more individuals," which would
include private wells.
In summary, EPA's various legislative statutes provide a range of guidance
on what ground waters to protect (Figure 11-7). In some of EPA's existing
statutes, ground water is not specifically mentioned; in others, EPA's
enforceable authorities are limited to ensuring that the quality of drinking
water supplied by public water systems is adequate.
67
PROPOSED STRATEGY
-------
a
60
o ,2
v
J
es
a-eliai
-s 3 q ,P Ł> > %
rr\ CO rrj PH ^> 0) -3
S^J o . CO ""^ 3
S
-------
In addition to these legislative considerations, the Agency also
considered its existing policies in addressing the question of what waters to
protect. In this regard, the Agency's basic ground-water policy states that
the ground-water resource will be protected to ensure quality for the highest
present or potential beneficial use. The highest beneficial use is defined as
drinking water. The Agency's basic policy is also based on differential
protection in regard to the use, value, and vulnerability of ground waters.
2. What Criteria Determine Protection
The second key part of the Agency's goal is identifying the criteria to be
used for determining protection. Again, the Agency's legislative authorities
provide varying guidance for addressing this issue (Figure II-7).
Federal Insecticide, Fungicide and Rodentlclde Act (FIFRA) - This
basic pesticide law requires the Agency to weigh the health and
environmental risks of the use of each pesticide against the benefits
of such use. Those pesticide uses which are found not to present an
unreasonable risk may be registered.
Safe Drinking Water Act (SDWA) - In contrast to FIFRA, the SDWA does
not require considerations of the benefits of any regulated chemicals,
including pesticides. Rather, the SDWA establishes a goal of
protecting public health from exposures to contaminated public water
supplies. SDWA standards are set as close as possible to those goals,
but must take into account the cost and availability of feasible
treatment technology to reduce contamination of water delivered to the
consumer.
Clean Water Act (CWA) - The stated goal of the CWA is to restore and
maintain the chemical, physical, and biological integrity of the
nation's waters. EPA has established human health protection criteria
for pesticides in edible fish tissue based on levels that provide
negligible or no significant risks.
Resource Conservation and Recovery Act (RCRA) - Under RCRA, the
contamination of ground water by hazardous waste facilities cannot
exceed standards based on background environmental levels, SDWA
standards, or levels that would pose a substantial present or
potential hazard to human health or the environment. Of particular
note, RCRA does provide EPA more flexibility in establishing
protection criteria for releases from nonhazardous waste facilities,
such as municipal landfills.
69
PROPOSED STRATEGY
-------
Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA) - CERCLA or "Superfund" must be considered when responding to
existing contamination. As amended by SARA in 1986, CERCLA now
requires that clean-up levels (i.e., protection criteria) be defined
in terms of applicable or relevant and appropriate regulatory
requirements of other environmental statutes, such as the SDWA and
CWA.
To date, the Agency has discussed the question of what criteria to use for
ground-water protection mainly in relationship to the regulation of waste
sites. This discussion has focused on both the differences within a statute
(i.e., RCRA requirements for hazardous waste facilities versus nonhazardous
waste facilities), as well as between statutes (i.e., RCRA versus CERCLA).
When pesticides are considered in this discussion, the extent of the
differences in legislative direction becomes even more pronounced.
As described above, FIFRA requires the Agency to consider the benefits of a
pesticide as well as its risks. Those risks considered reasonable under
FIFRA1s mandate may not be consistent with the regulatory policies established
under other environmental statutes. The potential for this discrepancy is
perhaps greater for ground water than for other pesticide concerns because of
the number of relevant statutes.
The options which EPA considered for the criteria for defining protection
are shown in Figure II-8 and include:
a) PRISTINE - Protection criteria based on pristine conditions would
require prevention efforts that are designed to achieve zero contamination
in waters chosen for protection. With this option, response efforts would
have to restore protected ground waters to zero contamination levels.
While an unspoiled environment is desirable, there are a number of
practical barriers to achieving such a goal. First of all, zero is not
scientifically measurable and therefore not attainable. Secondly, efforts
to attain pristine ground water would be enormously expensive and would
limit greatly the type of waters that could be targeted for such
protection.
70
PROPOSED STRATEGY
-------
03
i-H
UH
u
O G
2
r \ **H
CJ
2°
o
1 I
C/3
rt VH C
.g2J§
I! Ill
< Ť 3 -5 13
Ł* c S'B
5 -a 5 3 a
i^ua B
71
PROPOSED STRATEGY
-------
b) MAXIMUM CONTAMINANT LEVEL GOAL (MCLG) - The SDWA requires the Agency to
set a Maximum Contaminant Level Goal (MCLG) for any potential drinking
water pollutant at a level that has no known or anticipated adverse effect.
EPA's policy has been to set the MCLG at absolute zero for a chemical
proven to be carcinogenic (cancer-causing) in humans, or a probable
carcinogen in animal studies. For noncarcinogens, the MCLG is set at a
level corresponding to a percentage of the Acceptable Daily Intake (ADI) or
more recently, Reference Dose (RfD). '
In developing the MCLG policy, EPA considered setting the MCLGs for
carcinogens at the lowest levels that could be detected by modern
analytical technology (the limits of detection). The Agency also
considered setting MCLGs at levels that would pose insignificant or
negligible risks (see below). The Agency's most compelling argument for
choosing the more conservative option of absolute zero for probable
carcinogens is that the MCLG was not intended to be used as a practical
regulatory standard, but rather as a statement of the SDWA program's
general long-term aim.
Where the concern is for a carcinogenic pesticide in ground water, the use
of the MCLG as the protection criterion would have the same problems as the
pristine option. In this case, a measurable goal could not be established
because a zero level is not scientifically measurable. Furthermore,
prevention and response efforts could constantly be in doubt as the ability
to measure smaller and smaller levels of environmental contaminants
progresses. Use of the MCLG as the criterion for protection could also
skew public health and environmental priorities since this approach does
not consider the relative potency of different carcinogens, nor does this
* To simplify somewhat, the ADI is developed by first determining the
concentration of a chemical that shows no observable effect level (NOEL) in
animal tests. After factoring the size of humans and possible other
biological differences, the NOEL is divided by a margin of safety factor,
the magnitude of which is determined by the quality of the toxicology data
and other factors. EPA uses a percent of the ADI for setting an MCLG
because humans may be exposed to the chemical through other routes such as
food.
72
PROPOSED STRATEGY
-------
approach consider that a noncarcinogen could pose a much greater risk than
a weak carcinogen. Furthermore, as with the pristine option, the cost of
protecting, monitoring, and restoring ground water based on a zero level
may limit greatly the type of waters that could be targeted for such
protection.
c) NEGLIGIBLE RISK - EPA has applied the concept of negligible risk to
carcinogens. Substances shown primarily through controlled animal studies
to have the capacity to cause cancer (malignant tumors) are considered to
be carcinogens. In assessing the risks of these substances, EPA assumes
that there is no level of exposure that has a zero chance or risk of an
adverse effect. However, the risks are assumed to be proportional to the
level of exposure. Therefore, at some exposure level the risk posed by a
carcinogen can be considered to be insignificant or negligible.
EPA uses a number of "worst case" assumptions to estimate the risks to
humans from environmental exposures to carcinogens based on extrapolations
from animal studies. If a "worst case" or "upper bound" estimate of cancer
risk is one in a million (1 x 10 ) or less, the risk at that level of
exposure is generally considered to be insignificant or negligible.
The use of negligible risk as the basis for a protection criterion provides
a level that is considered very protective of human health. Such a goal
could be measurable, but for some chemicals the concentration of a chemical
at a negligible risk level may not be detectable. In this case, a decision
would have to be made to accept the limits of detection as an acceptable
level. Because of its stringency, a standard based on the concept of
negligible risk may not be achievable as a clean-up standard for certain
pesticide contamination incidents.
d) MCL STANDARD - Following the development of an MCLG, the SDWA requires
EPA to establish a Maximum Contaminant Level (MCL) that is the enforceable
standard used to guard the adequacy of the drinking water provided by
public water systems. The SDWA requires EPA to set the MCL as close as
73
PROPOSED STRATEGY
-------
possible to the MCLG, taking into account the cost and feasibility of
measuring and reducing the contamination. MCLs are set in a range that is
considered protective of human health.
MCLs as protection criteria have already been established for public water
systems, and as such they can provide measurable goals. In some cases,
though, MCL's may be difficult to achieve, particularly when they are used
to protect private well water or the ground-water resource. Like the
previous options, MCL's are not based on a consideration of the benefits of
the contaminants to society.
e) UNREASONABLE RISK - As mentioned earlier, FIFRA is a risk-benefit
statute and requires the weighing of the human health risks posed by a
pesticide's use against its benefits. In some cases, concentrations posing
a nonnegligible risk may be tolerated if the benefits of the pesticide's
use are found to be uniquely critical.
The key question for the Agency is how to develop a goal for protecting
ground water from pesticide contamination that is compatible with the require-
ments under each of its legislative mandates. From a prevention perspective,
FIFRA requires the Agency to weigh the benefits of a pesticide's use against
its risks. Obviously, EPA must attempt to prevent the creation of
contamination problems that would require corrective actions, such as treatment
by public water systems. From a response perspective, actions are based on
criteria (e.g., SDWA goals and standards) that do not consider the benefits of
pesticide use. The critical issue is whether the criteria used to define
protection under other legislation can be used as the basis for unreasonable
risk determinations under FIFRA.
SECTION 2: ERA'S PROPOSED POLICY POSITION
EPA's proposed environmental goal will be to protect the ground-water
resource with the key focus on preventing unacceptable contamination of current
and potential drinking water supplies. MCLs or other EPA-designated protection
74
PROPOSED STRATEGY
-------
criteria will be used as reference points for helping to determine unacceptable
levels of contamination. Specifically, the Agency will adopt the following
policies for protecting ground water from pesticide contamination:
1. The Agency will use a differential protection approach to
protect the ground-water resource. With this approach, the
Agency will focus protection efforts on ground waters that are
current or potential sources of drinking water or that are vital
to fragile ecosystems (Figure II-9). Additional measures may be
taken to ensure protection of certain "high priority ground
waters."
Ground water provides nearly half of the drinking water used in this
country. Regardless of whether that water is being provided through a
community public water system or to a private individual, it is not usually
monitored for the presence of pesticide residues, nor is it usually subject to
any treatment technology capable of removing low, but possibly health-
significant, levels of pesticides.
Under the SDWA, EPA is establishing standards which will require public
drinking water systems to identify, and where necessary, to remove pesticide
residues posing potential health concerns before supplying the water for use.
However, it will take substantial time and investment for public systems to
achieve this capability; these requirements also will not be applied to the
approximately 12 million private wells that supply drinking water to millions
of Americans. Thus, EPA must assume that contaminated ground waters which are
used as a source of drinking water may result in direct human exposure. It is
the Agency's position that protection of these ground waters is synonymous with
public health protection. As such, EPA's protection efforts must target those
ground-water resources that serve as drinking water sources.
Since the natural cleansing processes of ground waters can be extremely
slow, contamination of this resource poses a potential hazard for future
generations. Contaminated ground water could be used as a drinking water
source before being tested for contamination. Where contamination is
75
PROPOSED STRATEGY
-------
c
o
i
of)
H
o
GO
cs
s
is
08
-C
76
PROPOSED STRATEGY
-------
identified, efforts could be made to restore the ground water for use as a
drinking water source, but this option could present insurmountable
technological difficulties and exorbitant costs.
In practice, alternative water sources or point-of-use treatment, if
technology is available, may be the only viable preventive measures for a
community. Although local governments could regulate the placement and
construction of wells, there is the possibility that these ordinances may
eventually be ignored or overlooked before the ground water has been cleansed
by natural processes. For these reasons, EPA may have to assume that
contaminated ground water that is a potential drinking water source could
eventually result in human exposure. EPA's protection goal therefore includes
ground-water resources that are potential as well as current sources of
drinking water.
The need to protect the ground-water resource is further underscored by the
fact that ground waters provide approximately 30% of the annual base flow to
surface water systems. In certain dry areas of the country or during periods
of drought, ground-water flows to surface waters can have a more dominant role.
As such, the continued existence of fragile ecosystems may depend on the
quality of certain ground water. To meet its basic environmental protection
mission, EPA must focus protection efforts on ground-water resources from an
ecological perspective as well as from a public health concern.
As part of its differential protection approach, the Agency will take
additional measures to protect "high priority ground water." These "high
priority ground waters" may serve as irreplaceable sources of drinking water
for sizable communities, or they may be vital to the continued survival of
endangered species or critical ecosystems. For these situations, additional
measures, beyond baseline protective efforts, may be required to provide
further assurances that these, and perhaps other, "high priority ground waters"
are not contaminated or that they have priority for corrective actions, if
already contaminated.
77
PROPOSED STRATEGY
-------
2. EPA will use MCLs, as defined under the SDWA, as reference
points for helping to determine unacceptable contamination of
ground waters that are drinking water sources. When no MCL
exists. EPA will use interim drinking water protection criteria
as Its reference points. These will be equivalent to an MCLG
for noncarcinogenic pesticides and to a negligible risk level
for carcinogenic pesticides (Figure 11-10). The Agency will also
use ecologically based protection criteria as reference points
for helping to determine unacceptable contamination of ground
waters.
Under the 1986 SDWA Amendments, EPA is moving to establish new MCLs for
potential drinking water contaminants, including a number of pesticides. In
the interim, EPA will have available other drinking water protection criteria
that will be based on standard risk assessment procedures. For noncarcinogens,
EPA will establish these interim protection criteria based on a No Observable
Effect Level (NOEL) with appropriate margins of safety of two or three orders
of magnitude depending on the confidence in the toxicity data and other risk
assessment factors (this approach is essentially the same one used for setting
an MCLG for a noncarcinogen). For carcinogens, the interim protection criteria
will be set at a level that corresponds to a negligible risk, i.e., the level
of exposure that has an upper bound estimate of one in a million chance of
causing cancer (see previous description). Establishment of interim protection
criteria for pesticides in drinking water is jointly undertaken by EPA's Office
of Drinking Water and Office of Pesticide Programs. EPA has recently developed
interim levels for over 60 pesticides through the Agency's health advisory
process.
Since an MCL or an interim protection criteria is developed for human
health reasons, these levels could pose concern for fragile aquatic ecosystems.
Of particular concern would be pesticide contamination that would result in
risks to endangered species. Because the Agency's mandate is to protect the
environment as well as public health, EPA also establishes ecologically based
protection criteria. EPA's Office of Pesticide Programs
78
PROPOSED STRATEGY
-------
o
T-H
.2
*
u
-*-ť
at
5
1
79
PROPOSED STRATEGY
-------
will continue to work closely with the Office of Water Regulations and
Standards in the latter Office's development of such water quality criteria for
pesticides.
For response actions, the above criteria will be used as reference points
to help determine where and what measures should be taken to protect human
health and the environment should unacceptable levels of contamination be
reached. Contaminated ground waters that are current or potential sources of
drinking water or ground waters of ecological significance are all possible
candidates for corrective efforts. Highest priority attention, however, should
be given to responding to incidents of ground-water contamination where levels
exceed an MCL or an interim reference point and that water is used as a current
drinking water source.
For prevention efforts, the protection criteria, described above, will be
used as reference points for helping to define unacceptable levels of
contamination and to determine when certain pesticide management actions may be
needed to reduce the likelihood of ground-water contamination reaching or
exceeding such levels. Efforts to manage a pesticide's use will begin with
early indications of its potential to contaminate ground water. These early
indications can be based on information about the physical and chemical
properties of the pesticide, how and where it may be used, and predictions of
its fate in certain usage areas.
When a pesticide is found in ground water that is a current or potential
drinking water source, additional management actions may need to be triggered.
The need for, and the stringency of, these management actions will depend on
the number of sites where the pesticide is detected, and whether the levels
found are above or moving toward a reference point. In effect, EPA intends to
establish an "early-warning" or "yellow light/red light" management process
(Figure 11-11), whereby increasingly stringent control measures will be applied
in response to an increasing threat of a pesticide reaching or exceeding an
unacceptable level.
80
PROPOSED STRATEGY
-------
II
a
CM V V3
0 a g
a o> .2
§ 2 a
^ §0
I
Ł
I
u
o .2
Ł3 DO
C3
-------
EPA's rebuttable presumption will be that the risks posed by pesticide
contamination of a local underground source of drinking water, at or above the
MCL or an interim reference point, will be more significant than the benefits
derived from the pesticide's use in the area. Depending on the frequency and
scope of such contamination, EPA will consider the cancellation of the
pesticide's use in such areas as an appropriate response. However, a number of
factors would need to be consider that could make cancellation inappropriate.
For example, the benefits of using the pesticide in an area could be
substantial and there may be management measures, other than cancellation, that
could reduce contamination to acceptable levels. Also, the cancellation of a
pesticide's use would not be appropriate if the ground-water contamination
resulted from unusual circumstances such as an accident.
Before taking action to mitigate ground-water contamination threats, EPA
must also consider such action in the context of overall pesticide exposure
risks, including risks to applicators and farm workers and risks to the general
population through dietary exposures. The Agency will maintain its regulatory
flexibility to delay or modify ground-water protection measures should the
Agency find that pesticide substitutes or alternative use practices would
result in greater overall pesticide risks.
In conclusion, EPA's proposed goal is to protect the ground-water resource
with specific attention given to preventing unacceptable contamination of
current and potential drinking water supplies or ground water of ecological
importance. Additional measures may be required to provide further assurances
that certain "high priority ground waters" are not threatened by such
contamination.
EPA will use MCLs, as defined under the SDWA, as its basic point-of-
reference for determining unacceptable contamination for ground waters that are
current and potential drinking water supplies. When no MCL exists, EPA will
use an MCLG or its equivalent for noncarcinogenic pesticides and a negligible
risk level for carcinogenic pesticides as interim reference points. The Agency
will also use ecologically based protection criteria as reference points for
determining unacceptable ground-water contamination.
82
PROPOSED STRATEGY
-------
Pesticide Strategy
,Ť* PREVENTION
, , PROGRAM
RESPONSE
PROGRAM
83
PROPOSED STRATEGY
-------
CHAPTER 2
PREVENTION POLICY AND PROGRAM
Prevention of pesticide contamination of ground water is the centerpiece of
the Agency's strategy for protecting ground water. As part of its prevention
strategy, EPA will employ a multi-prong approach to prevent pesticides from
reaching an unacceptable level in ground water.
First, EPA will take uniform action for pesticides posing widespread
national concerns and will establish generic requirements for certain pesticide
use and disposal practices that pose unique ground-water threats independent of
area-specific ground-water conditions.
Secondly, EPA will adopt a differential approach to the management of
pesticide availability and use. Under this approach, prevention measures will
be tailored to an area's ground-water conditions to the extent feasible.
Certain State-wide or county-wide measures will be required by EPA. Additional
site-specific measures may be required in which the user will be responsible
for determining their applicability to a given application site based on
site-specific ground-water vulnerability or the user's location in an area of
"high priority ground water" (i.e., high-use/value ground waters).
Third, the Agency will encourage a strong State role in the local
management of pesticide use. Under this approach, a State will have the
opportunity to develop a pesticide management plan that may be the basis for
EPA's registration of a pesticide within that State. While the basis of a
State plan must be to meet EPA's goal of protecting ground-water resources, a
State will have flexibility in its management approach to better tailor
measures to local needs.
Pesticide users and registrants will also continue to have key roles in
protecting ground water. The users will be responsible for complying with
label instructions and keeping informed of ways to prevent ground-water
contamination, while the registrants will be responsible for monitoring certain
ground waters and improving communication to the users on proper use of their
85
PROPOSED STRATEGY
-------
products. Monitoring will play a major role in the prevention program by
identifying potential contamination problems early and triggering appropriate
pesticide management actions.
The next section discusses the options and factors that the Agency
considered in developing its prevention strategy. Following this section is a
detailed presentation of the Agency's proposed position on key aspects of the
prevention approach.
SECTION 1; FACTORS AND OPTIONS CONSIDERED
In designing its program for preventing ground-water contamination by
pesticides, the Agency addressed two strategic questions: (1) how to address
local variability and (2) what are the appropriate Federal-State roles (Figure
11-12). An important consideration, related to the latter issue, was
determining the role of the pesticide user and registrant in ground-water
protection. Another key consideration was how to control further contamination
of ground water once a pesticide has been detected in an area.
1. How to Address Local Variability
Since 1970, EPA has been responsible for regulating the use of pesticides
in the environment. Through its regulatory programs under FIFRA, the basic
pesticide law, the Agency has developed a number of tools for controlling
pesticide use in the United States. Foremost among these tools is the
authority to require extensive environmental and toxicological testing of
pesticides. Through its registration and reregistration programs, EPA can
require the manufacturer, or registrant, to conduct comprehensive testing of a
pesticide, including environmental fate studies that will indicate the
potential of a pesticide to leach into ground water.
Based on the results of these tests and other available data, the Agency
approves or disapproves certain or all uses of a pesticide. When the Agency
approves the use of a pesticide, it can further regulate the conditions of its
use by imposing certain requirements or restrictions on the pesticide's
labeling. Historically, the Agency has used product labeling as the major
86
PROPOSED STRATEGY
-------
-4,
O
W
H
H
CO
H
CO
87
PROPOSED STRATEGY
-------
vehicle for communicating information to the users regarding proper application
and disposal of pesticide products. For those pesticides that pose significant
risks but do not warrant complete removal from the marketplace, the Agency may
impose labeling requirements that change the rate, timing, or method of
application or that restrict its use to trained and certified applicators.
Under FIFRA, the States have the primary responsibility for enforcing the
proper use of pesticides, as defined by the EPA-approved label. States may
also require more stringent controls than the Federal Government for the use of
pesticides within their individual States.
For dietary exposures and applicator or farm worker exposures, a uniform,
national management approach is warranted. In the case of dietary exposures,
differences among regions of the country are usually not significant since our
food distribution system is national in scope. More important differences can
be found among males and females or among infants, children, and adults because
of differences in the diets of these subpopulations. Important differences
also exist among these groups in their susceptibility to pesticide toxicity.
For these reasons, the Agency generally evaluates the exposures from pesticides
in the food supply based upon national averages for these subpopulations.
Exposure to applicators or farm workers can also be regulated on a national
basis by considering the physical-chemical properties of the pesticide and by
requiring certain safety precautions on the label, such as protective clothing
requirements.
Unlike dietary and applicator exposure, the pesticides in ground water con-
cern does not lend itself easily to a uniform, national management approach.
As previously mentioned, the use and value of ground water varies extensively
across the country and as stated in the previous chapter, EPA will
differentiate its protection efforts according to these differences. The
vulnerability of ground water to pesticide contamination also varies
substantially depending on such area-specific factors as the depth to ground
water and the type of soil. Other factors that determine whether or not a
pesticide will reach the ground water are local agricultural practices, the
physical-chemical properties of the pesticides selected to deal with an area's
pests, and how and when these pesticides are applied. A more detailed
88
PROPOSED STRATEGY
-------
discussion of these factors can be found in the Problem Assessment of this
strategy and in several other documents (e.g., Pesticides in Ground Water:
Background Document, U.S. EPA 1986; Practices to Mitigate Contamination of
Ground Water from Pesticides Used in Crop Production, U.S. EPA, in draft).
In addition to distinctions in management plans based on the use and value
of ground waters, distinctions based on different vulnerability of ground water
may be appropriate.
Figure 11-13 illustrates an ideal approach to managing pesticides based on
differences in ground-water vulnerability to contamination. Ideally, prevention
measures would be tailored so that they provide the optimum level of protection
without undue restrictions. Any protective measures above this optimum line
for a given level of vulnerability would provide more protection than is
actually needed. Protective measures below this optimum line for a given level
of vulnerability would provide less protection than is actually needed. This
graph is used in the following presentation of three possible management
approaches for addressing the variability in ground-water vulnerability:
a) Uniform Approach - A uniform approach essentially ignores area
variability in vulnerability and applies the same prevention measures
uniformly to all areas. If EPA relied on a uniform national approach to
prevent ground-water contamination by pesticides, it would have to decide
if its prevention decisions should be based on a worst-case situation of
high vulnerability (Figure II-14a) or on a moderate case of medium
vulnerability (Figure II-14b).
A worst-case basis could result in a great deal of overprotection for less
vulnerable areas, while a moderate-case basis could result in both
overprotection of low-vulnerability areas and underprotection of
high-vulnerability areas. The obvious drawback of underprotection is the
likelihood of ground-water contamination exceeding acceptable levels as
defined by EPA's environmental goal. The problem with overprotection is
that it could result in the loss of valuable pesticide uses in important
farming areas of the country -- a situation that would not be compatible
with the intent of FIFRA.
89
PROPOSED STRATEGY
-------
c
o
T^*
-SP r
a
s
&:
§>
'88
I
90
PROPOSED STRATEGY
-------
a
a
03
§>
.
§§
Ji
p9pIAOJ
-------
b) Uniform Baseline Prevention Measures with Local Exemptions and
Additional Special Measures - Under this option, uniform baseline measures
would be established for a pesticide in the same manner as the above
option, but area-specific exemptions would be allowed for those places that
would otherwise be overprotected. Such an approach could be implemented
through a permit system in which exemptions from baseline requirements
would be allowed for less vulnerable areas. Additional special measures
could be applied on a case-by-case basis to those areas that would
otherwise be underprotected. These additional measures could be specified
on a label and the user made responsible for determining if they are
applicable to the user's particular area.
While addressing some of the concerns for overprotection and
underprotection of the previous option, this approach has some major
limitations. A permit system carries major administrative costs and can
place significant burdens on pesticide users. It would be highly
impracticable for EPA to operate a national system of area-specific
permits. Having the user determine the applicability of more restrictive
measures could result in compliance problems. The user may not have the
training to determine if the user's area is more vulnerable than the
general case and, therefore, underprotected by the uniform measures.
c) Differential Approach (Figure 11-15) - A third approach for addressing
area variability is to tailor prevention measures to different levels of
ground-water vulnerability. The number of vulnerability levels is
practicably limited by: (1) the technical ability to accurately
differentiate vulnerability; and (2) the number of different prevention
measures that could reasonably be used to provide differential protection.
Figure 11-15 divides ground water into three different vulnerability
levels. A different degree of stringency in prevention measures is then
applied to each of these three levels of ground-water vulnerability. While
there is still a likelihood of underprotection and overprotection measures
for any given area, the number of such measures would be reduced in
comparison to the first two options discussed above.
92
PROPOSED STRATEGY
-------
08 5
L-
c
^
D
QJ
I
I
1
J=
a
§>
d c
PQ
UOTP9JOJJ
93
PROPOSED STRATEGY
-------
This option requires the designation and mapping of specific areas, based
on ground water vulnerability, as well as the development of differential
measures for each level of vulnerable ground water. The success of this
option depends to a large extent on the degree of resolution (i.e., county,
farm, acre, etc.) in designating and mapping local vulnerability. Note
that such mapping would be in addition to mapping of ground waters by their
use and value.
Vulnerability to pesticide contamination may be fairly uniform across some
large areas, while in other areas it may vary on a farm-by-farm basis or
even on an acre-by-acre basis. Figure 11-16 presents the different degrees
of resolution that could be used as the basis for differentiating
agricultural areas by relative vulnerability. At one end of the spectrum
is resolution at the national level, which as previously described is the
Agency's basis for addressing dietary and applicator exposure concerns. At
the other end of the spectrum is resolution at the level of individual
acres. Although making determinations of vulnerability at the highest
degree of resolution would be the preferred technical basis for management,
the sheer number of decisions required by such an approach could be
overwhelming (See Figure 11-17). EPA may be able to manage a differential
approach to pesticide use at one degree of resolution, whereas a State may
be successful in conducting a management program at a much higher degree of
resolution. A State should also be in a better position to make decisions
on the use and value of ground water in a given location. Who should
determine the vulnerability and the use and value of ground water in an
area and who should manage a differential approach are the subjects of the
second strategic question.
2. What Are the Appropriate Federal/State Roles?
The options the Agency has considered for Federal and State roles in
addressing ground-water contamination using a differential approach are as
follows:
94
PROPOSED STRATEGY
-------
c
o
ťP4
IS
<
o
li
CO
u
O)
j
o
95
PROPOSED STRATEGY
-------
fl
Ł
v*
3
*
o
96
PROPOSED STRATEGY
-------
a) EPA Establishes Differential Measures/User Determines Applicability -
In this approach (Figure 11-18), the Agency would establish differential
protective measures for a pesticide based on ground-water use and value
considerations and/or different levels of vulnerability of the ground water
where the pesticide is being used or proposed for use. The Agency may
decide that certain pesticides cannot be used in areas of high use and
value and/or high vulnerability. For moderately vulnerable areas, the use
of the pesticide could be subject to special restrictions, such as changes
in the rate, timing, or method of application. Furthermore, representative
monitoring of ground water for the pesticide in these moderately vulnerable
areas could be required of the registrant to ensure that no threat of
unacceptable contamination emerges. For low vulnerability areas, special
ground-water protection measures might not be required, although there
might be applicable generic requirements, such as a requirement for special
measures near drinking water wells.
An important characteristic of this option is that the user would be
primarily responsible for determining the applicability of differential
requirements based on a required assessment of local vulnerability and the
user's location within an area of "high priority ground waters." The user
would base a decision on label directions and possibly on supplemental
instruction or training. One problem with this option is that most users
do not have the scientific background in hydrogeology or environmental fate
processes to make accurate field decisions. With this option, directions
must be provided that translate technical assessments of ground-water
vulnerability into directions that a user can understand and apply.
However, determinations of ground-water vulnerability to pesticide
contamination are very complex, and simple but effective label directions
for users are difficult. Because of these constraints, implementing this
option could likely result in misuse and possible unacceptable
contamination of ground water.
b) EPA Specifies Differential Measures for Individual Counties or States;
Users Determine Applicability of EPA-Specified Sub-County Measures (Figure
II-18b) - As with the previous option, the Agency would develop differen-
tial prevention measures based on ground-water use and value and/or
97
PROPOSED STRATEGY
-------
e r
00
as
C/5
0>
o
98
PROPOSED STRATEGY
-------
3
****
tin
99
PROPOSED STRATEGY
-------
different degrees of vulnerability, but in this option the Agency would
identify or map vulnerability areas on a county basis. This information
would be provided to the user on the label, supplemental labeling, or by
other means.
While EPA's designation of ground-water vulnerability could be based on
sub-county assessments, the actual management of pesticide use could only
occur, at best, at the county level because of administrative factors, such
as labeling constraints and enforcement considerations. In fact, there
might be certain situations in which EPA would decide to apply the same
protection measures to an entire State as a result of these administrative
difficulties. At this level of resolution, EPA would base minimum county-
or State-wide measures on the assumption that all ground waters in the area
are, at least, a current or potential drinking water source.
Since the vulnerability within a county can vary greatly, this approach
could unnecessarily apply stringent measures, including local bans, to
sub-county areas that are less vulnerable than the average for the county
in which they are located. Similarly, such variation could result in
underprotection for sub-county areas more vulnerable than a county average.
This latter possibility could cause the Agency to make overly conservative
decisions when classifying counties based on vulnerability. As with the
first option, the user would be required to make difficult location-
specific judgments on the applicability of prevention measures that would
be more stringent than the minimal county-wide requirements because of
site-specific vulnerability or the user's location within an area of "high
priority ground water."
c) State Specifies Differential Measures for Sub-County Areas Based on
EPA Criteria (Figure II-18c) - With this option, the State would have the
dominant role in determining differential prevention measures, but such
measures would be based on EPA criteria. The States would identify and map
their ground waters in terms of use, value and vulnerability and provide
pesticide users with explicit directions on where and how pesticides could
be applied.
100
PROPOSED STRATEGY
-------
fl
cs
a;
'o
101
PROPOSED STRATEGY
-------
The States should be able to provide a differential management approach
based on highly-specific area designation of ground-water vulnerability,
use and value. As such, the user in the field would have more explicit
directions as to where and how the pesticide could be used, and would not
have to determine local vulnerability. Another advantage to this option is
that the State could also closely tie user training and enforcement efforts
to its own differential approach.
Although the States are in a better position than EPA to understand local
conditions and establish a differential approach that is highly tailored to
these conditions, there are a number of drawbacks to this option. These
include the potential lack of uniformity among States and possible
political and legislative constraints within particular States, which may
jeopardize obtainment of EPA's environmental goal of protecting the
ground-water resource. The option could also result in the inefficient use
of State resources because of unnecessary duplicative efforts in developing
pesticide prevention measures.
SECTION 2; EPA'S PROPOSED POSITION
EPA will employ each of the three basic management approaches, described
above, to prevent pesticides from reaching unacceptable levels in ground water.
EPA will continue to develop uniform, national measures, but will also begin to
implement a differential management approach at the county level or, in some
cases, at the State level. A State will have the opportunity to take a stronger
role in local pesticide management through the development of a State
management plan. The responsibilities of pesticide users and registrants will
grow along with an increasing reliance on monitoring information.
EPA's specific strategic policies are as follows:
1. EPA will continue to take uniform action for pesticides
causing widespread, national concerns and will establish
generic prevention measures to address certain pesticide use
102
PROPOSED STRATEGY
-------
and disposal practices that pose ground-water threats
Independent of area-specific vulnerability. National uniform
measures will not be differentiated on the basis of local
differences.
Obviously, when a pesticide's use poses a serious, widespread ground-water
threat, EPA will take steps at the national level and, if necessary, impose a
regional or even a national cancellation of the use of the pesticide. Of
particular national concern are those general ground-water threats that are not
dependent on local vulnerability and require generic prevention measures. For
example, EPA has proposed regulations for the application of pesticides through
irrigation waters, often referred to as chemigation. This practice can
directly introduce pesticides into ground water if precautions, such as
anti-back siphoning devices, are not used.
EPA is also developing a rule to restrict the use of potential leaching
pesticides to certified applicators. The Agency is also considering the
development of national rules to address the potential problem of pesticide
applications too near a well which can result in "run-in" of pesticides into
ground water, a particular problem in areas with uncapped, abandoned wells.
Finally, EPA is considering additional generic rules and guidelines for
pesticide disposal and for preventing and handling leaks and spills, all of
which can be important sources of a number of pesticide concerns, including
ground-water contamination. For the disposal concern, EPA is looking at its
options under both FIFRA and RCRA.
2. EPA will also adopt a new approach of differential
management of pesticide use based on differences in ground-water
use, value and vulnerability to an extent t_h_at_ is
administratively feasible. County- or State-level measures based
on ground-water vulnerability will be employed, including use
cancellations. In some cases, the user will have to determine
the applicability of differential prevention measures based on
interpretation of local field conditions and the user's location
within areas of "high priority ground waters."
103
PROPOSED STRATEGY
-------
When a pesticide poses serious but localized risks due to local
ground-water vulnerability, an appropriate prevention approach is to remove the
threat where it exists and allow the use of the pesticide in other areas to
continue without undue restrictions. EPA's prevention measures will thus be
differentiated in their stringency on the basis of relative vulnerability of
local ground water to pesticide contamination. Because of a number of
administrative limitations, as mentioned earlier, EPA's prevention measures
will generally be differentiated at the county or State level. EPA will do its
best to assess the vulnerability of pesticide usage areas within counties and
to determine the appropriate mix of prevention measures necessary to protect
ground waters within the entire county. At this level of aggregation, EPA will
have to assume that all ground water, at a minimum, is a current or potential
drinking water source requiring protection.
Prevention measures will include minimum, county-wide requirements that
must be followed by all users within a designated county. For some counties,
the minimum measure may be a ban on a pesticide's use. For other counties, the
pesticide's use will be allowed, but minimum county-wide measures will range
from general advisories to extensive requirements involving changes in the
rate, timing, or method of application or other agricultural practices that can
influence pesticide movement to ground water. Additional measures, beyond
minimum county-wide requirements, could also be required of users in certain
areas of a county. The determination of the applicability of these additional
measures will be the responsibility of the user and will be based on
site-specific factors, such as the presence of ground-water conditions more
vulnerable than generally found in a county or the need to protect certain
"high priority ground waters," such as those within a drinking water wellhead
protection area.
In some cases, EPA may apply minimum prevention measures, including
geographic bans, to an entire State. Such a situation may occur where there is
generally uniform ground-water vulnerability to contamination by a pesticide in
all usage areas of a State. State-wide measures could also occur where EPA
believes the State does not have the ability to support a differential approach
to the management of pesticides, particularly from enforcement and user
education perspectives.
104
PROPOSED STRATEGY
-------
3. EPA will encourage the development of a strong State role in
area-specific management of pesticide use to protect the
ground-water resource. State pesticide management plans will be
used to strengthen EPA's foundation for decisions on pesticide
use. In some cases, the use of a pesticide in a State will
depend on the existence of and adequacy of such a State
management plan. Under its management plan, a State will
develop and implement highly tailored prevention measures based
on local differences in ground-water use, value and
vulnerability.
As discussed earlier, there are a number of limitations to an EPA-directed
differential management approach for pesticides at the county or state level.
Such an approach can prohibit or restrict the use of a pesticide unnecessarily
in some areas. This approach also places a major burden on the user to
determine the applicability of more restrictive measures that are based on
site-specific conditions that the user must assess. These disadvantages could
result in noncompliance and a failure of this approach to meet EPA's
environmental goal of protecting the ground-water resource. Therefore, the
Agency is looking for strong State involvement to determine where a pesticide
can, and cannot, be used without ground-water restrictions. This alternative
cooperative approach between EPA and a State will lessen the burden on the user
to determine the applicability of site-specific measures, and in turn, reduce
noncompliance and increase the likelihood of attainment of EPA's environmental
goal.
States often can have the technical expertise and have more specific
knowledge of local ground-water conditions and agricultural practices than EPA.
States are also likely to be in a better position to work more directly with
the user to ensure that potential ground-water contamination problems are
identified and that pesticides are properly used to avoid these problems. EPA
wants to strengthen and utilize the unique position of the States in efforts to
prevent ground-water contamination by encouraging the States to develop
pesticide management plans to protect their local ground waters.
105
PROPOSED STRATEGY
-------
Under a State management plan, the State would Identify where a pesticide
with ground-water contamination concerns is being used or is likely to be used.
The State would also use its knowledge of local ground-water resources and
determine where protection measures would be differentiated based on local
differences in the use and value as well as the vulnerability of ground waters.
The State would adopt prevention measures that would prevent unacceptable
contamination of current and future drinking water sources as well as ground
waters that are ecologically important. As part of its management plan, the
State could also identify areas with "high priority ground waters," such as
wellhead protection areas, where more stringent measures may be required.
In some cases, the State would obviously have to employ EPA-designated
measures for certain types of areas, such as local cancellations of high risk
pesticides in highly vulnerable ground-water areas. However, it is EPA's
intent that a State generally have the opportunity to select from a broad menu
of management measures (Table II-l) and to tailor prevention to local needs.
Some of these measures may be Best Management Practices (BMPs) which have been
developed and demonstrated by a state, perhaps under EPA's Nonpoint Source
Program. Those measures which are chosen by a State will have to be supported
by strong, coordinated education and enforcement programs.
Development and implementation of a State management plan will require the
active participation of all key state agencies including the departments of
agriculture, public health, water, natural resources, or environmental
protection. A State's pesticide management plan will be a key component of its
overall ground-water protection strategy and should be consistent with its
Wellhead Protection Program, if one exists. The State should take a holistic
approach to protecting its water resources and realize the important
relationship between ground-water protection and surface water quality. The
State pesticide management plan should be consistent with any State clean water
strategy for protecting surface waters.
106
PROPOSED STRATEGY
-------
fi
QJ
Ł
=
0>
DJD
C
^
o;
tt
P
Pesticide
1 Moratorium Areas
| Wellhead Protection Areas
| Well Set Backs (Buffer Zones)
a
_o
'4-*
o
03
G
O
U
PH
0)
Q
o
i-H
4 ť
O
Future Well Requirements: Lo
Change in Rate of Application
Ť S
o o
is -i i
'S g
.0 ^
'E ^
rv PH
< <
fi .
^ij ^^^
0 °
W) ^
a R
a 1
H S
.a .a
^) D
W) bJO
r* r~"
v-J ť i
c^ c$
ť i ť i
rM i-M
U U
Advance Notice of Application
Integrated Pest Management
Best Management Practices
Additional Monitoring
^o
03
0
Additional Training and Certifi
107
PROPOSED STRATEGY
-------
When deciding on the national registration of a pesticide with ground-water
contamination concerns, EPA will consider a State's management plan. EPA will
work with each State to determine if a pesticide's use can be managed locally
by the State to prevent or reduce the threat of ground-water contamination. In
some situations, EPA will require a State-specific label or supplemental
labeling with the approved conditions of use based on a State management plan.
In other cases, EPA will have to take steps, including possible State-wide
cancellations, to control the use of a pesticide that poses a significant
ground-water threat if there is no adequate State management plan that can
reasonably be expected to prevent or reduce the threat of unacceptable
contamination.
While over the longer-term, States may develop generic management plans
that can be applied to any specific pesticide, the Agency expects that the
States will adopt chemical-specific management schemes for those pesticides
that pose major ground-water risks. As EPA and the States gain practical
experience with the concept of State management plans, and as our understanding
of approaches for mitigation of pesticide contamination increases, the need for
chemical-specific schemes may diminish.
Development of a management plan does not necessarily have to be
accomplished by each State acting alone. Where ground-water resources are
continuous under State boundaries and contamination problems in one State could
threaten the quality of waters of another State, it would make sense for
adjacent States to coordinate their State plan development. In the case of
chemical-specific schemes, certain States may also find multi-State or regional
management schemes desirable to obtain or continue EPA's registration of a
pesticide that is important to a regional crop.
One of EPA's key responsibilities under this approach will be to provide as
much technical support to the States as possible, including information on the
physical/chemical/toxicological characteristics of pesticides of concern and
their behavior in the environment. To meet this responsibility, EPA will keep
abreast of monitoring information to detect new pesticide contamination
concerns as well as to assess the effectiveness of various management
approaches. The Agency will also keep the States informed of national trends
108
PROPOSED STRATEGY
-------
and will facilitate exchange of information between the States on the problems
and successes of different local management approaches. Through the Office of
Ground-Water Protection's Wellhead Protection Program, and through several CWA
grant programs, including the nonpoint source authorities, EPA will provide
financial and technical support to States for the development and
implementation of their State management plans. The Agency will also coordinate
with other Federal agencies, such as USDA and USGS, to conduct research and to
communicate results to the States on pesticide behavior, monitoring methods,
best management practices, and other technological information needs.
Table II-2 provides scenarios for how pesticides that pose a moderate to
high ground-water threat would be managed in States with different
vulnerability situations. Two options are presented: 1) no State plan; and 2)
State plan in place.
4. The user's role in preventing ground-water contamination is
pivotal; the user's decisionmaking in the field must be better
supported.
Regardless of whether a pesticide is managed under an EPA-State cooperative
management approach or an EPA-only approach, the user will continue to be in
the unique position of directly controlling the use of pesticides in the field.
Thus, the user has the responsibility to seek better understanding of
ground-water concerns. At a minimum, a user must follow the instructions found
on the label of each pesticide product and when required, be trained and
certified in the proper use of the pesticide.
However, we cannot expect the typical pesticide user to make highly
technical decisions on his own. The best approach is to provide the user with
clear instructions either to not use a pesticide or to use it in a certain
manner in highly specified areas. Such areas should be familiar to the user,
or a map should be provided that clearly delineates the area. To some degree,
a State's management plan should have the capability to provide such
specificity.
109
PROPOSED STRATEGY
-------
a
O
OH
CO
52
U
fi S
O co
co
S
o
u
CO
I
o
Is
O
fi
03
Ł
_i i
ement
OJD
03
fi
03
O>
2
fi
03
Ł
0)
s
CO
0
fc
fi
.2
^^^
03
2
33
0
3
i§
.S
s i
Ml CO _,
381
ill
IP
rr? °
III
statewide cancellation
3
1
1
o3
S .§Ł>
O M -;
S §2
& B§
1 H
t-j jj i
60 g -§r)
W C/2 2
§ a
23 n C
g § S
i 1 I i
y 2 fT S
0 I
^ 3 3 CT1
S o o g
[3 trt (_ri
O Ťt-3 Ťt*3 W)
nil
ii 1
1 1 1 1 1
1 1 § 1 1
1 1 1 1 1
1 1 } J i
c2 Ł 6 o S
<*-(
!§ r3
'S j^-g
^Ťv G w
1 if
| 1|
"§ a*§ ^
S coBS
no
PROPOSED STRATEGY
-------
However, as discussed earlier, the area-specific nature of ground water
could still require the user to identify vulnerable ground water in the user's
specific fields and to determine if special prevention measures are needed.
This will be especially true where the State has not taken an active management
role. There are no easy formulas to provide exact "answers" to the user
through label instructions alone. The Agency recognizes that it and the States
must provide better support to the user for making proper use decisions. USDA,
with its existing field network, also can play a key role.
A major vehicle for improving user decisions in the field is applicator
training and certification programs. EPA is establishing a generic rule for
restricting the use of those pesticides with potential ground-water threats to
certified applicators. Working with the States and the Cooperative Extension
Service, EPA is attempting to improve and expand training and certification
programs so that users may become more aware of ground-water concerns and the
measures necessary to protect this vital resource.
5. Registrant responsibilities will need to grow in three
areas: (1) technical support for the user in the field; (2)
ground-water monitoring to ensure the adequacy of pesticide
management plans in protecting ground water; and (3) the
development of safer alternative pesticides.
While there are State and Federal programs that can shoulder some of the
need, registrants will need to play a greater role in assisting the user in the
proper, environmentally sound application of their products.
In the future, registrants will also be expected to conduct representative
monitoring of ground water in areas where pesticide use occurs and where ground
water may be vulnerable. These studies will be critical to ensure that protec-
tion efforts are working. Where there is a potential ground-water contamina-
tion concern, certain new registrations may be granted on the condition that
the registrant conduct monitoring studies. Continued registration of certain
pesticides, under a State management plan, may also hinge on monitoring data to
111
PROPOSED STRATEGY
-------
O
C3
CD
OJ
>
JT;
I Ł& Is
._ ^ g 3 g^g.9
Ł
Ja
co
CO
a s :*
S S T3 rfe ^, ^^
s 5
-------
Indicate the environmental adequacy of those management efforts. Registrants
may find it beneficial to pool their efforts to establish a joint and effective
monitoring capability.
Finally, registrants will be expected to develop safer alternative
pesticides that do not pose a threat to ground water. This message will become
increasingly obvious to the registrants as the Agency and the States continue
to restrict or cancel the uses of more pesticides that threaten the quality of
the nation's ground waters.
6. Increased monitoring of pesticides in ground water is
critical to the implementation of this strategy. EPA will
establish an "early-warning," or "yellow light/red light,"
approach to prevent further area contamination, once detected.
The approach will use the MCL or other EPA-specified protection
criteria as the point of reference to evaluate, and when
necessary, change pesticide management plans.
Even though the Agency has developed a number of models for predicting
ground-water contamination, there is still a great deal of uncertainty in
identifying the exact locations of areas vulnerable to contamination and in
estimating the levels of contamination that could be reached in the ground
waters of these areas. Thus, monitoring of pesticides in this environmental
medium is a critical need that can provide the needed feedback to determine the
success or failure of pesticide management efforts.
EPA or a State, under its management plan, will direct or conduct
monitoring of pesticides in ground water that is representative of where the
pesticide use occurs and where there is a potential ground-water problem. When
pesticide contamination is found to be moving toward an MCL or other EPA-
designated ground-water protection criteria, EPA or the State will revise the
pesticide's management plan, as necessary, to prevent further contamination.
The stringency of new measures will depend on the likelihood of contamination
113
PROPOSED STRATEGY
-------
reaching or exceeding these reference points in current or future drinking
water or ground water of ecological importance. Factors to be considered are
the levels found, the number of contamination sites, whether the trend is
upward, and the cause, if known (Figure 11-19).
As discussed above, registrants will often be responsible for conducting
monitoring in representative areas of a pesticide's use. The registrant may
also be required to do site-specific monitoring in an area where contamination
has already occurred if the registrant desires to continue the registration of
the pesticide in that area or other areas with similar pesticide use
characteristics and ground-water vulnerability.
114
PROPOSED STRATEGY
-------
03
O
U
a
a
6X
3
115
PROPOSED STRATEGY
-------
Pesticide Strategy
PREVENTION
PROGRAM
RESPONSE
PROGRAM
117
PROPOSED STRATEGY
-------
CHAPTER 3
RESPONSE POLICY AND PROGRAM
One of the most challenging tasks facing the Agency and the States is
developing a strategy for responding to ground-water contamination resulting
from normal use of pesticides. EPA's approach will be to work closely with the
States in their efforts to remove public health threats. Where a pesticide has
reached unacceptable levels, strong actions will be taken to prevent further
contamination. The Agency will continue to emphasize the development and
enforcement of MCLs to ensure the adequacy of drinking water from public water
systems. In the future, the Agency will focus on coordinating enforcement
activities under a number of Federal authorities so that responsible parties
can be identified and required to take the actions necessary to eliminate
imminent health threats. On a case-by-case basis, EPA will assist the States
by providing funds for removal actions, including provisions of alternative
drinking water, when a imminent public health threat exists.
SECTION 1; FACTORS CONSIDERED
To develop its response strategy, the Agency had to address three
questions: what are the appropriate Federal/State roles; what are the
appropriate authorities and actions for what type of contamination; and who is
liable for contamination (Figure 11-20). To address these questions, several
site-specific conditions must be considered, including: the type of ground
water affected, the source or circumstances that resulted in contamination, and
the appropriate type and degree of response needed.
The type of ground water that has been contaminated is a critical
consideration in determining both the level of concern and the authorities
available to conduct or require a response action. For instance, the SDWA
addresses only the contamination of public water systems, defined as those
systems providing drinking water to 15 or more permanent service connections or
25 people a day for at least 60 days a year. Under the SDWA, public water
systems are required to provide water satisfying drinking water standards
(i.e., no contamination exceeding MCLs). Although SDWA regulations do not
119
PROPOSED STRATEGY
-------
vo
I
O
o
*- ^ ri C
slaa
o. ^. ,
^^^ 2^^ ^^^ ^H
OH MH o O
Ť S^
p p ^ */J
S 3 c3 ^
"^ "^ 43 ^
120
PROPOSED STRATEGY
-------
apply to private wells, most States use these or their own similar standards to
inform well owners of possible health risks, and in some cases, State laws may
require closure of private wells that do not meet drinking water standards.
The source and circumstances of contamination at a given site are other
important considerations in determining the appropriate authority for
responding to contamination. Under the Comprehensive Emergency Response,
Compensation and Liability Act (CERCLA), EPA has the authority to clean-up
contamination and recover the cost of these actions from responsible parties.
Cost-recovery, however, is specifically excluded when the contamination is a
result of pesticide use in accordance with label requirements. Recovery of
cost from responsible parties is a possibility, however, when contamination is
a result of illegal disposal or leaks and spills.
The type and degree of response must be based on the specifics of each
case. The type of response needed bears on all of the three questions
Federal/State roles, appropriate authority, and who will be liable. An initial
response action can be limited to investigating the site to evaluate the extent
and severity of the contamination problem. Should a site pose an immediate
public health threat, corrective actions can be taken such as providing a
temporary, alternative source of drinking water. Eventually, more permanent
solutions may have to be considered, including the establishment of long-term
capacity to treat the contaminated water as it is drawn for actual use. In
this regard, aquifer restoration will be a very costly, if not an
impracticable, type of response when contamination is widespread.
SECTION 2; EPA's PROPOSED POSITION
EPA's response strategy will be to address the problem of ground-water
contamination on a number of fronts. The Agency will exercise its own
authorities and will also encourage and assist State efforts to remove imminent
public health threats posed by pesticides in drinking water. Specifically, the
Agency proposes the following policies:
1. Where a pesticide has reached unacceptable levels in ground
water, strong actions must be taken to stop further
121
PROPOSED STRATEGY
-------
contamination. These actions can range from enforcement actions
to modification of the way a pesticide is managed, including
geographic restrictions on the pesticide's use.
An essential part of any response action is eliminating the threat of
further contamination of ground water. As discussed in the prevention section,
the capacity to respond to reports of ground-water contamination must be
developed. When a pesticide is initially detected in ground water, a response
should include increased monitoring as well as site-specific determinations as
to the extent, source and circumstances of the contamination. Enforcement
actions should be taken to prevent further incidents where contamination is
found to be a result of misuse. On the other hand, where contamination is the
result of approved use of a pesticide, modifications in EPA's or a State's
management of the pesticide must occur to minimize the likelihood of further
contamination. When a pesticide level has reached or exceeded an MCL or other
reference point as a result of normal agricultural use, a more aggressive
stance needs to be taken, including the possibility of prohibiting further use
of the pesticide in the affected areas.
When the State lacks a management plan to respond to incidents of
contamination, EPA will have to decide whether to allow continued use of a
pesticide in an affected area. Because the Agency has limited capacity to make
site-specific decisions, its choices would most likely be made at a more
aggregated level, such as a county or perhaps even an entire State. In this
event, infrequent occurrences of contamination in an area may not be sufficient
for EPA to undertake county-wide or State-wide cancellation of a pesticide's
use. On the other hand, when repeated incidents clearly point to a ground-water
threat from a registered use in an area, EPA would have to consider cancelling
the use of the pesticide in an entire county or State. This situation
underscores the benefits of a State management plan in which area use decisions
can be tailored to local circumstances.
2. EPA will encourage a strong State role in responding to
contamination. A State's management plan should consider the
development of a valid corrective response scheme.
122
PROPOSED STRATEGY
-------
Because a State is more attuned to local conditions, it should have the
dominant role in ensuring that corrective actions are taken to address threats
to its citizens' health posed by pesticide contamination of ground water. At a
minimum, a State needs to take steps to identify and track ground- water
contamination in order to determine if current drinking water wells will be
affected and to notify users of the potential health risks. By integrating its
Federally delegated authorities and resources with its own authorities and
resources, a State can provide an effective overall scheme for responding to,
and where needed, correcting, public health problems resulting from pesticide
contamination of ground waters. In particular, the response scheme should
identify the resources and the appropriate corrective actions needed when
contamination is found as a result of the approved use of a pesticide.
With respect to funding for response actions, the Agency believes that
States should have the lead. In establishing a corrective response capability,
a State needs to select from a number of alternative mechanisms. In this
regard, a number of States have already adopted or are considering funding
mechanisms, such as general State revenues, a State trust fund generated by a
tax on pesticide use, or a requirement for users or registrants, jointly or
alone, to provide corrective actions.
EPA is also considering the development of a number of assistance measures
to indirectly support States in their corrective response efforts. These
measures range from site-specific and general technical assistance to providing
public information and education. Table II-4 outlines some of these measures.
In summary, a State's corrective response scheme should be a key component
of its pesticide management plan. The presence of such a response scheme does
not, however, change the primary objective or emphasis in a State management
plan from one of prevention. Recognizing that contamination is still a
possibility even under the best management efforts, States should develop
corrective mechanisms to respond effectively should this possibility become a
123
PROPOSED STRATEGY
-------
Table II-4
Indirect EPA Response Options
Technical Assistance
Site-Specific:
Review of corrective action plans developed by State/local authorities
Guidelines for sample analysis and data interpretation
Development of health advisory notices
General:
Development of pesticide fact sheet
Development of treatment technology
Development of State/local training programs for monitoring,
risk assessment, and mitigation methods
Contingency Pl'ai guidelines
Information on pesticide contaminations
Public Information/Education Programs
Telephone hotline for public inquiries
Pollution insurance information for ground water users
Low-interest loan information for ground water users
Press releases on contamination problems/solutions
124
PROPOSED STRATEGY
-------
reality. In the event that a State lacks a corrective response scheme, EPA may
consider the option of denying registration, for use in that State, of
pesticides that could pose major threats to ground water.
3. EPA will continue to develop and stress enforcement of MCLs.
Under the SDWA's emergency powers, EPA will consider issuing
orders requiring responsible parties to provide alternative
water supplies when levels of pesticides present an imminent and
substantial endangerment to public health.
In response to the 1986 amendments to the SDWA, EPA is accelerating the
development of MCLs, particularly those for pesticides considered to be
potential drinking water contaminants. Once these MCLs are finalized, the
States will be able to better assess the quality of drinking water supplied by
public water systems. In those cases where a public water system draws on a
contaminated ground-water supply, the State must require the system to reduce
contamination to acceptable levels before allowing public consumption of the
water. A system may treat the water to remove the contamination, blend the
water with noncontaminated water to reduce levels in delivered water, or close
the well and find an alternative water supply. In some cases, it may not be
feasible for a drinking water system to comply with such requirements, and
States may need to close the system or provide resources to the system to
comply with these requirements. Exemptions to meeting the MCL can be allowed
by a State during the time it takes for a system to implement necessary
corrective measures, but the system must notify its users that it is providing
water with contaminants exceeding MCLs.
Under the 1986 SDWA Amendments, EPA has been given expanded authority to
respond to contamination of a public drinking water system or an underground
drinking water supply when it may present an imminent and substantial
endangerment and when State or local authorities have not acted to protect
public health. Under this expanded authority, EPA may issue orders requiring
the provision of alternative water supplies by persons who caused or
contributed to the endangerment. EPA will consider such action where a public
system drawing on pesticide-contaminated ground water poses imminent and
substantial endangerment to public health.
125
PROPOSED STRATEGY
-------
4. EPA and the States will place greater emphasis on
coordinating FIFRA. SDWA, and CERCLA enforcement activities to
identify parties responsible for ground-water contamination as a
result of the misuse of pesticides, including illegal disposal
or leaks and spills.
Under CERCLA, EPA has the authority to require corrective actions by
parties responsible for ground-water contamination as a result of pesticide
misuse, including illegal disposal or leaks and spills. The Agency can also
recover the costs of cleaning up a site resulting from illegal disposal or
leaks and spills. EPA and the States need to take advantage of the CERCLA
enforcement authorities by closely coordinating their efforts under FIFRA and
the SDWA with those of CERCLA.
5. On a case-by-case basis, EPA may assist States by
undertaking CERCLA Fund-financed removal actions to provide
alternative drinking water supplies where there is an imminent
human health threat.
The Agency may consider on a case-by-case basis providing CERCLA Fund
financing for immediate, short-term response actions. Actions under CERCLA's
Removal Program can only provide for alternative drinking water and other types
of short-term responses to eliminate imminent human health threats. The Agency
will seek cost recovery when the contamination is shown to be a result of
misuse and a responsible party is identified.
6. The question of who should pay for long-term corrective
actions at sites contaminated by the approved use of a pesticide
is a legislative question. EPA believes that several aspects of
the problem must be considered before a decision can be made.
When contamination of ground water appears to be a result of registered
use, and that use was based on sound data and reasonable efforts to predict the
potential for contamination, it is not clear who should be considered the
responsible party. In this situation, several parties have some involvement,
126
PROPOSED STRATEGY
-------
including the user who applied the pesticide, the registrant who brought the
pesticide to market, and EPA and state agencies who registered the product.
The well owner may even bear some responsibility if he knowingly placed his
well in a high-risk setting.
EPA is not in the position to make liability decisions. This question is
one to be resolved by Congress or State legislatures. When contamination is a
result of use in accordance with the label, all the parties described above
could be considered to have some responsibility. Liability in this situation,
perhaps, should be limited to mitigating imminent public health threats with
provisions for alternative drinking water or point-of-use water treatment.
127
PROPOSED STRATEGY
-------
C/3
W
CO
Si
H^ N**'
STATES
l
ic
128
PROPOSED STRATEGY
-------
PART III
IMPLEMENTATION ISSUES
-------
PART III
IMPLEMENTATION ISSUES
The purpose of this third and final part of the document is to present a
number of implementation issues raised by the Agency's proposed strategy
(Figure III-l). The Agency plans to address some of these issues in its final
strategy. A proposed EPA position on several of these issues, however, will
have to await the development of future regulatory proposals for specific
pesticides in ground water concerns. The Agency is seeking public comment on
all of these issues at this time.
131
PROPOSED STRATEGY
-------
c
o
"ft
S
§
If
CO
O
o
I
g
ffi M
\Tf\ ^"^
cd
G
s
o>
M
o.
s
132
PROPOSED STRATEGY
-------
CHAPTER 1
IMPLEMENTATION - ENVIRONMENTAL GOAL
EPA's goal is to protect the ground-water resource with the focus on
preventing unacceptable contamination of current or potential drinking water
supplies or ground waters of ecological importance. Protection efforts will be
differentiated based on the use and value of different ground waters.
Additional protective measures, beyond baseline protection, may be required to
provide further assurances that certain "high priority ground waters" are not
threatened by unacceptable contamination.
Two key implementation issues underlying EPA's goal are: 1) the definition
of potential drinking water; and 2) the definition of high-priority ground
water (Figure III-2).
EPA's Ground-Water Protection Strategy (GWPS) defines three basic classes
of ground water:
t Class I: Special Ground Waters are those that both are highly
vulnerable to contamination because of the hydrological characteristics
of the areas under which they occur and are characterized by either of
the following two factors:
a) Irreplaceable, in that no reasonable alternative source of drinking
water is available to substantial populations; or
b) Ecologically vital, in that the aquifer provides the base flow for
a particularly sensitive ecological system that, if polluted, would
destroy a unique habitat.
Class II: Current and Potential Sources of Drinking Water and Waters
Having Other Beneficial Uses are all other ground waters that are
currently used or are potentially available for drinking water or other
beneficial use.
Class III: Ground Waters not Considered Potential Sources of Drinking
Water and of Limited Beneficial Use are ground waters that are heavily
saline, with Total Dissolved Solids (TDS) levels over 10,000 mg/1, or
are otherwise contaminated beyond levels that allow cleanup using
methods reasonably employed in public water system treatment. These
ground waters also must not migrate to Class I or II ground waters or
have a discharge to surface water that could cause degradation.
133
PROPOSED STRATEGY
-------
O
VH
Q
a
s
S
O
a
v.
a
60
*ť*
HH
C3 g
O
,
(4H
3
t/3
00
-------
In 1986, the Agency issued draft Guidelines for classifying ground water
that further define the classes, concepts, and key terms in the GWPS and
describe procedures and information needs for classifying ground water on a
site-by-site basis. The Guidelines are now being revised to reflect comments
received and are expected to be issued in final form in 1988. The Agency
intends to develop methods and procedures that are appropriate for area-wide or
anticipatory classification within the next year that can be used for sources,
such as pesticides, that are not suited to site-by-site classification.
More than half of the States are now developing and implementing area-wide
anticipatory classification systems of their own. In addition to State
classification systems, most States are expected to implement the new Wellhead
Protection Program under the 1986 amendments to the Safe Drinking Water Act.
In this program, States will delineate protection areas around public water
system wells and develop and implement management plans for controlling
potential sources of contamination (including pesticides).
For the pesticide strategy, EPA hopes to be able to build upon the
foundation in the EPA Ground-Water Protection Strategy and draft Guidelines,
State ground-water protection strategies and anticipatory classification
systems, and the Wellhead Protection Program as a means for determining where
baseline and additional protection measures should apply.
1. Definitions and Processes for Identifying Potential Drinking Water
In some major farming areas of the country, ground water may be found very
near the surface and thus be easily subject to contamination by agricultural
chemicals. Such ground water could have inherent potential as a drinking water
source, i.e., low salinity and sufficient yield. However, some of this water
would have little, if any, potential as a source of drinking water because of
its remoteness from human dwellings or the availability of preferred,
alternative sources, including deeper aquifers or surface water systems. As
stated in Part II, the proposed goal of this strategy is to protect ground
water that is a potential, as well as current, drinking water source. Concerns
have been raised that major farming dislocations could occur in some
agricultural States if remote shallow aquifers with low potential as drinking
135
PROPOSED STRATEGY
-------
water are protected in the same manner as other potential drinking water
sources. Conversely, concern has also been raised that other ground waters
classified as potential drinking water should receive additional protection
because they are in areas of rapid population growth where demand for drinking
water is expected to escalate rapidly.
Factors other than inherent drinking water potential might have to be
considered when designating protected ground waters. A State may prefer to
classify certain ground water in some areas as a low drinking water source
because of its location in what are primarily cropping areas with no current or
projected drinking water wells within a specified distance. In effect, such an
approach would ease the stringency of prevention measures for certain
agricultural areas with low-potential sources of future drinking water so as to
continue the economic benefit of agricultural production. On the other hand, a
State may want to be more protective of certain potential drinking water where
rapid population growth is expected to create a high demand for drinking water
in the near future. Thus, for agricultural areas, where much of the ground
water will be classified as potential drinking water, the Agency is seeking
comment on how to deal with the broad range of circumstances that may occur.
The Agency is seeking comments on the following specific questions:
How serious are both of these concerns?
How can these concerns be dealt with under the classification
guidelines?
Should subclasses be established for higher or lower levels of
protection for certain high or low potential drinking waters? What
should the criteria be?
Should EPA establish criteria and/or procedures for the States to make
classification decisions for agricultural areas?
Should the criteria and/or procedures be mandatory?
What action should EPA take if a State chooses not to use a
classification scheme?
136
PROPOSED STRATEGY
-------
2. What definition and process should be used to identify "high priority
ground waters"?
EPA's goal is to provide differential protection to ground water based on
its use and value. Specific attention will be given to preventing unacceptable
contamination of those waters that are a current or potential source of
drinking water (i.e., Class II). Under this strategy, special attention,
including where necessary, additional protection measures, will be given to
certain "high priority ground waters." A key issue in the implementation of
this differential approach is the definition, and the process, for identifying
"high priority ground waters."
One possible means of identifying "high priority ground waters" is to use
the Agency's draft Guidelines for site-specific classification of ground
waters. These guidelines identify "special ground waters" that are to be
afforded the highest level of protection from point source contamination.
These "special ground waters" are highly vulnerable to contamination and are
either (1) an irreplaceable drinking water source for a substantial population
or (2) ecologically-vital to unique habitats or endangered species.
Another possible option is to add to those areas with Class I ground
waters, Wellhead Protection Areas (WHPAs) as the basis for defining "high
priority ground waters." The 1986 SDWA amendments established the Well Head
Protection (WHP) Program, which provides EPA with the authority to grant
resources to a State to establish Wellhead Protection Areas (WHPA) for each
public drinking water well. A WHPA is defined as the area around a public well
that can impact the quality of ground water drawn by the well. Based upon
Federal guidance and assistance, the States must develop and implement
necessary measures to protect the water supply within WHPAs.
Another possibility is to apply the designation of "high priority ground
waters" to specific areas around all drinking water wells regardless of whether
they are public or private wells. Under this option, WHPAs would be used for
public wells, and for private wells, a "buffer zone" or "well setback" of a
specified size would be used. The advantage of this option is that it would
137
PROPOSED STRATEGY
-------
allow for additional protection for water supplies, including private wells
that are likely to be at higher risk than public wells due to their location,
depth, or construction.
With regard to this second implementation issue, the Agency is soliciting
comments on the following questions:
How should the Agency define "high priority ground waters" for
protection measures beyond those of baseline efforts? Should Well
Head Protection Areas be included along with Class I areas?
Should the definition include buffer zones around private wells?
f Should the States be responsible for identifying these areas using EPA
criteria or their own criteria?
Should the identification and extra protection for "high priority
ground waters" be a State prerogative?
What actions should EPA take in the event that a State is unwilling or
unable to identify these areas?
138
PROPOSED STRATEGY
-------
CHAPTER 2
IMPLEMENTATION - PREVENTION
An important component of EPA's prevention program is a coordinated
Federal-State differential management approach in which the States will take
the lead in making local pesticide use decisions based on local ground-water
use, value, and vulnerability. The role of EPA in this management scheme will
be to provide oversight, develop standards, and provide assistance to States
in developing their pesticide management plans. As part of its management
plan, a State will assess where there is a potential for ground-water
contamination by pesticides and will implement control measures necessary to
prevent or reduce the sources of such contamination. The State's pesticide
management plan will also be based on meeting EPA's environmental goal of
protecting the ground-water resources with specific attention given to
preventing unacceptable contamination of current and potential drinking water
or ground waters of ecological importance. MCLs or other EPA-designated
protection criteria will be used as the points of reference for helping to
determine unacceptable contamination.
Another key component of EPA's prevention program is the establishment of
effective programs for anticipatory monitoring and data analysis. To meet
this need, the Agency or a State, under its management plan, will establish an
"early-warning approach" in response to reports of ground-water contamination.
After a pesticide is detected in ground water, the Agency or a State will
apply increasingly stringent measures as the pesticide is detected at higher
levels and with greater frequency.
Implementation of EPA's strategic approach for preventing ground-water
contamination raises a complex web of issues. To simplify, we can group these
issues into six categories: (1) generic national control measures; (2)
barriers to a differential approach; (3) State management plans - criteria,
EPA oversight/support and use; (4) support of user decisionmaking; (5)
research and development priorities; and (6) monitoring/early-warning system -
mechanism and criteria (Figure III-3). The following is a discussion of these
139
PROPOSED STRATEGY
-------
0>
3
o
PH
VH
0
a.
§
CO
a
ťH
03
and Criteria
mis
o
.2 o
fi ^
5 ^
S Ł
c/o
VH
00
03
O
&
G
O
u
13
G
O
ii
4->
03
fc
_O
8
G
O
o3
W)
mplemen
3
00
VH
(U
pq
8
c
u
oo
41
G
Q
§
03
(D
oo
oo
00
w>
^G
O
I
o
140
PROPOSED STRATEGY
-------
issues. At this stage in the development of its pesticide strategy, EPA is
looking for specific comments on these and other implementation issues before
establishing its final strategy.
1. Generic National Control Measures
For pesticides that pose a widespread and serious threat to ground water,
the Agency will continue to take national control measures, such as
cancellations or suspensions, to protect the ground-water resource. The
Agency will also continue to develop generic preventive measures for
mitigating ground-water contamination as a result of agricultural practices.
With respect to this latter area, the Agency has initiated rulemaking to
restrict the use of ground-water contaminating pesticides to certified
applicators and has initiated a generic labeling requirement for chemigation.
In addition, EPA has initiated a project to examine how various agricultural
practices contribute to ground-water contamination.
Some of the questions which are raised are:
t What agricultural practices can be regulated effectively through
generic national regulations? How should these practices be regulated?
Through labeling?
What types of disposal measures can be addressed at the national level?
( FIFRA or RCRA?)
t How should the States and USDA be involved in the development of
national control measures?
2. Barriers to Implementation of a Differential Approach
In the past, EPA has taken a uniform national approach in making its
pesticide management decisions. Only recently has the Agency begun to address
concerns, such as endangered species, which require a more localized management
approach. Similar to the problem of protecting endangered species, the
pesticides in ground water concern will require a differential management
approach. However, there are a number of important differences which make the
management of the ground-water problem more difficult to implement than the
endangered species protection efforts. Whereas endangered species protection
141
PROPOSED STRATEGY
-------
requirements are primarily limited to geographically defined usage bans,
ground-water protection measures will include both usage bans and use
modifications. Without extensive State involvement, a pesticide user would be
responsible for complying both with minimum county or State-wide measures and
with special, more stringent measures for site-specific high-vulnerability or
high-risk situations (e.g., close proximity to drinking water wells). The user
must determine if his pesticide application site falls into this situation.
Before developing its final differential management approach, EPA is
seeking comments on the following implementation questions:
What types of control measures should EPA consider for differential
prevention based on local conditions? Should EPA consider such
measures as changes in the rate, timing, and method of application or
other farming practices that could influence pesticide movement to
ground water? Should the user be required to determine the
applicability of "measures" based on site-specific conditions? What
types of measures should be considered as special site-specific
requirements?
What are the possible labeling approaches for minimum county- or
State-wide prevention measures? How should information be provided to
the user to determine applicability of additional special measures to
his usage area - through labeling, supplemental labeling, and/or
training?
How can a county-by-county differential approach be enforced? How can
additional special measures be enforced? What are the barriers? How
can they be overcome? Will users understand and cooperate with a
differential approach?
2. State Management Plans - Criteria. EPA Oversight, and Support
The variability of the ground-water resource dictates that the States must
play a dominant role in managing pesticide use within their boundaries.
Through the development of State-specific management plans, the States can
tailor prevention measures to their local conditions. EPA will take the State
management plan into consideration in making its pesticide registration
decisions. In fact, EPA may cancel a pesticide use because of ground-water
concerns in those States that lack an adequate management plan.
142
PROPOSED STRATEGY
-------
Numerous implementation issues are associated with such a Federal/State
management effort, including:
What criteria should EPA use to determine the adequacy of a State
management plan? Should EPA review specific State decisions on
classifying ground waters, determining prevention measures, or
conducting monitoring? Or, should EPA limit its review to a State's
general capability by assessing such factors as legislative authority,
committed resources, political barriers, technical expertise, and
administrative capability? Or, should EPA review the actual plan?
Should EPA develop specific requirements, or should only guidelines be
established for the States to follow in developing their management
plans? What basic types of criteria should be developed: vulnerability
classification; use and value classifications (including the definition
of "high-priority ground water"); or prevention measures for specific
ground water conditions? Should State management plans focus on
implementing EPA requirements at a higher level of resolution (i.e.,
sub-county instead of county level)? To what degree should a State have
the flexibility to develop alternative measures, including
nonregulatory approaches such as user education and training? Under
what conditions would the State have maximum flexibility?
What actions should EPA take when a State's management plan is
inadequate or nonexistent? What types of monitoring data would
indicate that an existing State management plan is inadequate? What
other factors should be considered?
How should pesticide labeling be used to reflect Federal/State
protective measures? Is supplemental labeling or user training the
best way to communicate detailed local requirements? What other
alternatives are available?
What level of resources is needed by a State to develop management
plans? Are most States currently funding or considering funding
pesticide management programs to protect ground water?
How can a State coordinate the development of a management plan among
its various agencies? How can the Federal government stimulate
coordination within a State and among several States when contamination
crosses State borders?
3. Support of User Decisionmaking
The user is in the unique position of directly controlling the use of a
pesticide in the field. The proper use of a pesticide will depend largely on
the user's understanding and ability to carry out directions which are
specified on the label or provided by other means. Instructions that clearly
dictate exactly where a pesticide can and cannot be used, based on familiar
143
PROPOSED STRATEGY
-------
geographic landmarks or boundaries, are the most easily implemented
requirements, particularly if a map is provided.
However, this level of detail is not feasible on a national scale. As a
consequence, the user may have to assess the applicability of certain
prevention measures based on a number of site-specific conditions, including
the proximity of wells, the depth to ground water, or the type of soil at the
site of application. These decisions may sometimes be difficult for users to
make, but they are critical for an effective ground-water protection program.
As part of its strategy, EPA proposes to provide better technical information
to users for making these types of decisions. Some of the questions which are
associated with meeting this objective include:
How can the Federal Government (e.g., EPA, USDA) and the States
effectively transmit information to users? Are there ways to eliminate
or reduce any liability concerns?
How can certification and training programs assist the user in making
decisions that would affect ground water in his area?
How can registrants assist the user with regard to proper use of a
pesticide? Should EPA and the States require registrants to provide
technical assistance to users?
4. Research and Development Priorities
Recognizing that research is an essential element of EPA's efforts to
protect ground water, the Agency asked its Science Advisory Board (SAB) on
July 10, 1984, to review the Agency's ground-water research program. An
executive committee of the SAB summarized the current status of ground-water
research activities and presented a number of recommendations for increased
attention as well as new initiatives for research. Some of the SAB's
recommendations include options pertaining to agricultural chemicals in ground
water. Since the issuance of the SAB's report, EPA's Office of Research and
Development has initiated a number of ground-water research program reviews to
explore ground-water research priorities and to develop a more coordinated
program within the Agency, as well as with other Federal and State agencies.
144
PROPOSED STRATEGY
-------
The Agency would like to build on the results of the SAB's report and the
Agency's efforts to improve its ground-water research programs by seaking
comments on the following issues:
t Monitoring: What steps should EPA take to enhance the development of
ground-water sampling and analytical methods? How can the development
of these techniques be coordinated with USGS? What type of quality
assurance/quality control procedures are needed? How can EPA determine
the effectiveness of State monitoring capabilities?
Fate and Transport: What types of research should the Agency
conduct/sponsor to predict the fate and transport of pesticides in
ground water? How effective are current ground-water models in
evaluating pesticide behavior in ground water due to physical-chemical
processes? How can EPA improve its program of field evaluation of
prediction techniques?
Risk Assessment: What types of research studies would best enable the
Agency to assess potential risk from pesticides in ground water?
Should the Agency develop risk scenarios for populations dependent on
public versus private water supplies?
t Technology Transfer and Technical Assistance: How can the Agency
coordinate the transfer of research data within EPA and with other
Federal and State agencies? How can the Federal government and the
States get information to the users? Is there a need for a national
training center?
t Agricultural Practices: What types of research on agricultural
practices are needed? Should this type of research be conducted by
EPA, USDA, or registrants?
Disposal and Leaks and Spills Technology: What types of research are
needed to improve pesticide disposal technology? Who should fund it?
Is research needed to improve containment practices for preventing
leaks and spills of pesticides? If so, what types of methods should be
examined?
5. Monitoring and Early-Warning System Mechanism and Criteria
A key element of the prevention strategy is the development of an
anticipatory monitoring system to identify emerging problems and to assess the
success of pesticide management plans. A number of implementation questions,
however, need to be addressed regarding this element of the strategy,
particularly in regard to the concept of an "early warning" or "yellow
light/red light" approach.
145
PROPOSED STRATEGY
-------
Based on monitoring data, when should the Agency or States change the
management of a pesticide's use within an area? At what levels and
frequency of reported contamination should action be taken?
Is it necessary first to determine the cause of contamination before
changing the management of a pesticide use?
146
PROPOSED STRATEGY
-------
CHAPTER 3
IMPLEMENTATION - RESPONSE
In responding to pesticide contamination of ground water, the Federal
Government, States, and local governments must coordinate their actions, with
the States taking the lead role. Acting together, they must establish the
mechanisms to stop further contamination quickly in an area where pesticide
concentrations in ground water have reached unacceptable levels. Under its
pesticide management plan, a State can tailor pesticide management more
precisely than EPA. However, when a State fails to respond, the Agency will
take regulatory action for an entire county or even a State, if necessary, to
remove the threat of further contamination.
As a key component of its pesticide management plan, a State should develop
a corrective response scheme and determine the best mechanism for supporting
corrective actions for contamination resulting from pesticide use in accordance
with label directions. Working with the States, EPA will coordinate FIFRA,
SDWA, and CERCLA enforcement activities to identify responsible parties who
must correct ground-water contamination problems resulting from pesticide
misuse. EPA will continue to develop MCLs for pesticides, which the State will
use to ensure that public water systems are not supplying drinking water with
unacceptable levels of pesticide contamination. On a case-by-case basis, EPA
will assist the States through Superfund removal actions. These removal
actions will focus largely on providing alternative water supplies or other
immediate actions to remove imminent public health threats.
Key implementation questions for the Agency's response strategy include
(Figure III-4):
t When would it be appropriate for EPA to consider not registering a
pesticide in a State that does not have a corrective action scheme?
What indirect EPA responses, including technical assistance to the
States or national public information and educational efforts (see
Table III-l), should be a priority for development?
147
PROPOSED STRATEGY
-------
S.
a
(D
CM
w
O
L*
c
o
CO ~'
Ł
PH O
a
.^o
*ť*
t^H
g
^ O
c
w
co '
G -*-
2 I
-4ť <-(
2 ť
8$
i-H Q
CO II
C -y
O &
UŁ
v-i
O
Ł
PQ
o
43
00
CO
V
CO
G
O
PH
to
Indirect EPA
Development
CO
i-H 17 (
CO ^
co C
w
,_, w
T3 (^
3oi
^<
00 J
GU
ja o^
S w
^u
>T3
O 0)
a
o
G
I(
e
e
I-H
§
148
PROPOSED STRATEGY
-------
Table III-l
Indirect EPA Response Options
Technical Assistance
Site-Specific:
Review of corrective action plans developed by State/local authorities
Guidelines for sample analysis and data interpretation
Development of health advisory notices
General:
Development of pesticide fact sheet
Development of treatment technology
Development of State/local training programs for monitoring,
risk assessment, and mitigation methods
Contingency Plan guidelines
Information on pesticide contaminations
Public Information/Education Programs
Telephone hotline for public inquiries
Pollution insurance information for ground water users
Low-interest loan information for ground water users
Press releases on contamination problems/solutions
149
PROPOSED STRATEGY
-------
What can be done to facilitate coordination of enforcement activities
under FIFRA, RCRA, SDWA, and CERCLA to identify parties responsible for
contamination resulting from misuse, such as illegal disposal or leaks
and spills?
When should EPA consider assisting a State under the Agency's CERCLA
removal program? What should be the criteria for defining an imminent
health threat resulting from pesticide contamination of drinking water?
150
PROPOSED STRATEGY
------- |