National Primary Drinking Water Regulations: Ground Water Rule
Federal RegisterMay 10, 2000
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 141 and 142
[WH-FRL-6584-4]
RIN 2040-AA97
National Primary Drinking Water Regulations: Ground Water Rule
AGENCY:
Environmental Protection Agency (EPA).
ACTION:
Notice of proposed rulemaking.
SUMMARY:
EPA is proposing to require a targeted risk-based regulatory strategy for all ground water systems. The proposed requirements provide a meaningful opportunity to reduce public health risk associated with the consumption of waterborne pathogens from fecal contamination for a substantial number of people served by ground water sources.
The proposed strategy addresses risks through a multiple-barrier approach that relies on five major components: periodic sanitary surveys of ground water systems requiring the evaluation of eight elements and the identification of significant deficiencies; hydrogeologic assessments to identify wells sensitive to fecal contamination; source water monitoring for systems drawing from sensitive wells without treatment or with other indications of risk; a requirement for correction of significant deficiencies and fecal contamination (by eliminating the source of contamination, correcting the significant deficiency, providing an alternative source water, or providing a treatment which achieves at least 99.99 percent (4-log) inactivation or removal of viruses), and compliance monitoring to insure disinfection treatment is reliably operated where it is used.
EPA believes that the combination of these components strikes an appropriate regulatory balance which tailors the intensity or burden of protective measures and follow-up actions with the risk being addressed. In addition to proposing requirements for ground water systems, EPA requests comment on ways to address the problem of transient providers of water who furnish drinking water to large numbers of people for a limited period of time. One possible solution is to adopt alternative definitions for “public water systems” which is currently defined as “one that serves 25 or more people or has 15 or more service connections and operates at least 60 days per year. EPA is only requesting comment on this issue. The Agency is not today proposing to change the definition of “public water system ,” or modify related provisions. If EPA decides to take action on this issue, EPA will publish a proposal at a later date.
DATES:
The EPA must receive comments on or before July 10, 2000.
ADDRESSES:
References, supporting documents and public comments (and additional comments as they are provided) are available for review at EPA's Drinking Water Docket #W-98-23: 401 M Street, SW, Washington, DC 20460 from 9 a.m. to 4 p.m., Eastern Time, Monday through Friday, excluding Federal holidays.
You may submit comments by mail to the docket at: 1200 Pennsylvania Ave., NW, Washington, DC 20460 or by sending electronic mail (e-mail) to ow-docket@epa.gov. Hand deliveries should be delivered to: EPA's Drinking Water Docket at 401 M Street, SW, Washington, DC 20460.
For access to docket materials, please call 202/260-3027 to schedule an appointment and obtain the room number.
FOR FURTHER INFORMATION CONTACT:
For general information, contact the Safe Drinking Water Hotline, telephone (800) 426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding Federal holidays, from 9 a.m. to 5:30 p.m. Eastern Time. For technical inquiries, contact the Office of Ground Water and Drinking Water (MC 4607), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., N.W. Washington, DC 20460; telephone (202) 260-3309.
SUPPLEMENTARY INFORMATION:
Regulated Entities
Entities potentially regulated by the Ground Water Rule are public water systems using ground water. Regulated categories and entities include:
Category
Examples of regulated entities
Industry
Public ground water systems.
State, Local, Tribal, or Federal Governments
Public ground water systems.
This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. This table lists the types of entities that EPA is now aware could potentially be regulated by this action. Other types of entities not listed in this table could also be regulated. To determine whether your facility is regulated by this action, you should carefully examine the applicability criteria in § 141.400(b) of this proposed rule. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding section entitled
FOR FURTHER INFORMATION CONTACT
.
Abbreviations Used in This Notice
AWWA: American Water Works Association
ASDWA: Association of State Drinking Water Administrators
AWWARF: American Water Works Association Research Foundation
BMP: Best Management Practice
CDC: Centers for Disease Control and Prevention
CT: The residual concentration of disinfectant multiplied by the contact time
CWS: community water system
CWSS: Community Water System Survey
DBP: disinfection byproducts
ELR: Environmental Law Reporter
EPA: Environmental Protection Agency
FR: Federal Register
GAO: Government Accounting Office
GWR: Ground Water Rule
GWS: ground water system
HAA5: Haloacetic acids consisting of the sum of mono-, di-, and trichloroacetic acids, and mono-and dibromoacetic acids
HAV: Hepatitis A Virus
ICR: Information Collection Rule
IESWTR: Interim Enhanced Surface Water Treatment Rule
IT: UV irradiance multiplied by the contact time
m: meter
ml: milliliters
MCL: maximum contaminant level
MCLG: maximum contaminant level goal
mg/L: milligrams per liter
MPN: most probable number
MWCO: molecular weight cut-off
NCWS: non-community water system
NTNCWS: non-transient non-community water system
PCR: polymerase chain reaction
PWS: public water system
RO: reverse osmosis
RT-PCR: reverse-transcriptase, polymerase chain reaction
SBREFA: Small Business Regulatory Enforcement Fairness Act
SDWA: Safe Drinking Water Act
SDWIS: Safe Drinking Water Information System
Stage 1 DBPR: Stage 1 Disinfectants/Disinfection Byproducts Rule
Stage 2 DBPR: Stage 2 Disinfectants/Disinfection Byproducts Rule
SWAPP: Source Water Assessment and Protection Program
SWTR: Surface Water Treatment Rule
TCR: Total Coliform Rule
TNCWS: transient non-community water system
TTHM: total trihalomethanes
UIC: Underground Injection Control
USGS: United States Geological Survey
US EPA: United States Environmental Protection Agency
UV: ultraviolet radiation
WHP: Wellhead Protection
Table of Contents
I. Introduction and Background
A. Statutory Authority
B. Existing Regulations
1. Total Coliform Rule
2. Surface Water Treatment Rule and Interim Enhanced Surface Water Treatment Rule
3. Information Collection Rule
4. Stage 1 Disinfectants/Disinfection ByProducts Rule
5. Underground Injection Control Program
6. Source Water Assessment and Protection Program (SWAPP) and the Wellhead Protection (WHP) Program
C. Industry Profile—Baseline Information
1. Definitions and Data Sources
2. Alternate Definition of “Public Water System” and the Problem of Short-term Water Providers
3. Number and Size of Ground Water Systems
4. Location of Ground Water Systems
5. Ownership of Ground Water Systems
D. Effectiveness of Various Best Management Practices in Ground Water Systems
1. EPA Report on State Ground Water Management Practices
2. ASDWA Analysis of BMPs for Community Ground Water Systems
3. EPA Report on Ground Water Disinfection and Protective Practices
E. Outreach Activities
1. Public Meetings
2. Review and Comment of Preliminary Draft GWR Preamble
II. Public Health Risk
A. Introduction
B. Waterborne Disease Outbreak Data
C. Ground Water Occurrence Studies
1. Abbaszadegan et al. (1999) (AWWARF Study)
2. Lieberman
et al.
(1994, 1999) (EPA/AWWARF Study)
3. Missouri Ozark Aquifer Study #1
4. Missouri Ozark Aquifer Study #2
5. Missouri Alluvial Aquifer Study
6. Wisconsin Migrant Worker Camp Study
7. EPA Vulnerability Study
8. US-Mexico Border Study
9. Whittier, California, Coliphage Study
10. Oahu, Hawaii Study
11. New England Study
12. California Study
13. Three State PWS Study (Wisconsin, Maryland and Minnesota)
D. Health Effects of Waterborne Viral and Bacterial Pathogens
E. Risk Estimate
1. Baseline Risk Characterization
2. Summary of Basic Assumptions
3. Population Served by Untreated Ground Water Systems
4. Pathogens Modeled
5. Microbial Occurrence and Concentrations
6. Exposure to Potentially Contaminated Ground Water
7. Pathogenicity
8. Potential Illnesses
10. Request for Comments
F. Conclusion
III. Discussion of Proposed GWR Requirements
A. Sanitary Surveys
1. Overview and Purpose
2. General Accounting Office Sanitary Survey Investigation
3. ASDWA/EPA Guidance on Sanitary Surveys
4. Other Studies
5. Proposed Requirements
6. Reporting and Record Keeping Requirements
7. Request for Comments
B. Hydrogeologic Sensitivity Assessment
1. Overview and Purpose
2. Hydrogeologic Sensitivity
3. Hydrogeologic Barrier
4. Alternative Approaches to Hydrogeologic Sensitivity Assessment
5. Proposed Requirements
6. Request for Comments
C. Cross Connection Control
D. Source Water Monitoring
1. Overview and Purpose
2. Indicators of Fecal Contamination
3. Proposed Requirements
4. Analytical Methods
5. Request for Comments
E. Treatment Techniques for Systems with Fecally Contaminated Source Water or Uncorrected Significant Deficiencies
1. Overview and Purpose
2. Proposed Requirements
3. Public Notification
4. Request for Comments
IV. Implementation
V. Economic Analysis (Health Risk Reduction and Cost Analysis)
A. Overview
B. Quantifiable and Non-Quantifiable Costs
1. Total Annual Costs
2. System Costs
3. State costs
4. Non-Quantifiable Costs
C. Quantifiable and Non-Quantifiable Health and Non-Health Related Benefits
1. Quantifiable Health Benefits
2. Non-quantifiable Health and Non-Health Related Benefits
D. Incremental Costs and Benefits
E. Impacts on Households
F. Cost Savings from Simultaneous Reduction of Co-Occurring Contaminants
G. Risk Increases From Other Contaminants
H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates
I. Benefit Cost Determination
J. Request for Comment
1. NTNC and TNC Flow Estimates
2. Mixed Systems
VI. Other Requirements
A. Regulatory Flexibility Act (RFA)
1. Background
2. Use of Alternative Definition
3. Initial Regulatory Flexibility Analysis
4. Small Entity Outreach and Small Business Advocacy Review Panel
B. Paperwork Reduction Act
C. Unfunded Mandates Reform Act
1. Summary of UMRA Requirements
2. Written Statement for Rules With Federal Mandates of $100 Million or More
3. Impacts on Small Governments
D. National Technology Transfer and Advancement Act
1. Microbial Monitoring Methods
E. Executive Order 12866: Regulatory Planning and Review
F. Executive Order 12898: Environmental Justice
G. Executive Order 13045: Protection of Children from Environmental Health Risks and Safety Risks
1. Risk of Viral Illness to Children and Pregnant Women
2. Full Analysis of the Microbial Risk Assessment
H. Consultations with the Science Advisory Board, National Drinking Water Avisory Council, and the Secretary of Health and Human Services
I. Executive Orders on Federalism
J. Executive Order 13084: Consultation and Coordination With Indian Tribal Governments
K. Plain Language
VII. Public Comment Procedures
A. Deadlines for Comment
B. Where to Send Comment
C. Guidelines for Commenting
VIII. References
I. Introduction and Background
The purpose of this section is to provide background on existing regulations that affect ground water systems and current state practices.
A. Statutory Authority
This section discusses the Safe Drinking Water Act (SDWA) requirements which EPA must meet in developing the Ground Water Rule (GWR).
EPA has the responsibility to develop a GWR which not only specifies the appropriate use of disinfection but, just as important, addresses other components of ground water systems to ensure public health protection. Section 1412(b)(8) states that EPA develop regulations specifying the use of disinfectants for ground water systems “as necessary.” Under these provisions, EPA has the responsibility to develop a ground water rule which specifies the appropriate use of disinfection, and, in addition, addresses other components of ground water systems to ensure public health protection.
B. Existing Regulations
This section briefly describes the existing regulations that apply to ground water systems. These rules are the baseline for developing the GWR. The regulations that will be discussed include the Total Coliform Rule (TCR)(US EPA, 1989a), Surface Water Treatment Rule (SWTR)(US EPA, 1989b), Interim Enhanced Surface Water Treatment Rule (IESWTR)(US EPA 1998d), Information Collection Rule (ICR)(US EPA, 1996b), Stage 1 Disinfectant/Disinfection Byproducts Rule (Stage 1 DBPR)(US EPA, 1998e), Underground Injection Control Program (US EPA, 1999g) and the Source Water Assessment and Protection Program/Wellhead Protection Program.
1. Total Coliform Rule
The Total Coliform Rule (TCR), promulgated on June 29, 1989 (54 FR 27544)(US EPA,1989a) covers all public water systems. The rule protects public water supplies from disease-causing organisms (pathogens), and it is the most important regulation applicable to drinking water from ground water systems.
Total coliforms are a group of closely related bacteria that are generally free-living in the environment, but are also normally present in water contaminated with human and animal feces. They generally do not cause disease (there are some exceptions). Specifically, coliforms are used as a screen for fecal contamination, as well as to determine the efficiency of treatment and the integrity of the water distribution system. The presence of total coliforms in drinking water indicates that the system is either fecally contaminated or vulnerable to fecal contamination.
The TCR requires systems to monitor their distribution system for total coliforms at a frequency that depends upon the number of people served and whether the system is a community water system (CWS) or non-community water system (NCWS). The monitoring frequency ranges from 480 samples per month for the largest systems to once annually for some of the smallest systems. If a system has a total coliform-positive sample, it must (1) test that sample for the presence of fecal coliform or
E. coli,
(2) collect three repeat samples (four, if the system collects one routine sample or fewer per month) within 24 hours and analyze them for total coliforms (and then fecal coliform or
E. coli,
if positive), and (3) collect at least five routine samples in the next month of sampling regardless of system size.
Under the TCR, a system that collects 40 or more samples per month (generally systems that serve more than 33,000 people) violates the maximum contaminant level (MCL) for total coliforms if more than 5.0% of the samples (routine + repeat) it collects per month are total coliform-positive. A system that collects fewer than 40 samples per month violates the MCL if two samples (routine or repeat samples) during the month are total coliform-positive. For any size system, if two consecutive total coliform-positive samples occur at a site during a month, and one is also fecal coliform/
E. coli
-positive, the system has an acute violation of the MCL, and must provide public notification immediately. The presence of fecal coliforms or
E. coli
indicates that recent fecal contamination is present in the drinking water.
The TCR also requires a sanitary survey every five years (ten years for a protected, disinfected, ground water system) for every system that takes fewer than five samples per month (the monitoring frequency for systems serving 4,100 people or fewer, which is approximately 97% of GWS). Other provisions of the TCR include criteria for invalidating a positive or negative sample and a sample siting plan to ensure that all parts of the distribution system are monitored over time.
2. Surface Water Treatment Rule and Interim Enhanced Surface Water Treatment Rule
The Surface Water Treatment Rule, promulgated in June 29, 1989 (54 FR 27486)(40 CFR Part 141, Subpart H)(US EPA 1989b), covers all systems that use surface water or ground water under the direct influence of surface water. It is intended to protect against exposure to
Giardia lamblia,
viruses, and
Legionella,
as well as many other pathogens. The rule requires all such systems to reduce the level of Giardia by 99.9% (3-log reduction) and viruses by 99.99% (4-log reduction). Under this rule, all surface water systems must disinfect. The vast majority must also filter, unless they meet certain EPA-specified filter avoidance criteria that define high source water quality. More specifically, the SWTR requires: (1) A 0.2 mg/L disinfectant residual entering the distribution system, (2) maintenance of a detectable disinfectant residual in all parts of the distribution system; (3) compliance with a combined filter effluent performance standard for turbidity (
i.e.,
for rapid granular filters, 5 nephelometric turbidity units (NTU) maximum; 0.5 NTU maximum for 95% of measurements (taken every 4 hours) during a month); and 4) watershed protection and other requirements for unfiltered systems. The SWTR set a maximum contaminant level goal (MCLG) of zero for
Giardia,
viruses, and
Legionella.
The MCLG is a non-enforceable level based only on health effects.
On December 16, 1998, EPA promulgated the Interim Enhanced Surface Water Treatment Rule (IESWTR) (63 FR 69478)(US EPA, 1998d). The IESWTR covers all systems that use surface water, or ground water under the direct influence of surface water, that serve 10,000 people or greater. Key provisions include: a 2-log
Cryptosporidium
removal requirement for filtered systems; strengthened combined filter effluent turbidity performance standards (1 NTU maximum; 0.3 NTU maximum for 95% of measurements during a month); individual filter turbidity provisions; disinfection benchmark provisions to ensure continued levels of microbial protection while facilities take the necessary steps to comply with new disinfection byproduct (DBP) standards; inclusion of
Cryptosporidium
in the definition of ground water under the direct influence of surface water and in the watershed control requirements for unfiltered public water systems; requirements for covers on new finished water reservoirs; sanitary surveys for all surface water systems regardless of size; and an MCLG of zero for
Cryptosporidium.
In a parallel rulemaking, EPA has proposed a companion microbial regulation for surface water systems serving less than 10,000 people, the Long Term 1 Enhanced Surface Water Treatment Rule.
3. Information Collection Rule
The Information Collection Rule, promulgated on May 14, 1996 (61 FR 24368)(40 CFR part 141, Subpart M)(US EPA, 1996b), is a monitoring and data reporting rule. The data and information provided by this rule will support development of the Stage 2 Disinfection Byproducts Rule and a related microbial rule, the Long Term 2 Enhanced SWTR, scheduled for promulgation in May 2002.
The ICR applied to large water systems serving at least 100,000 people, and ground water systems serving at least 50,000 people. About 300 systems operating 500 treatment plants were involved. The ICR required systems to collect source water samples, and in some cases finished water samples, monthly for 18 months, and test them for
Giardia, Cryptosporidium,
viruses, total coliforms, and either fecal coliforms or
E. coli.
The ICR also required systems to determine the concentrations of a range of disinfectant and disinfection byproducts in different parts of the system. These disinfection byproducts form when disinfectants used for pathogen control react with naturally occurring total organic compounds (TOC) already present in source water. Some of these byproducts are toxic or carcinogenic. The rule also required systems to provide specified operating and engineering data to EPA. The required 18 months of monitoring under the ICR ended in December 1998.
As noted earlier, the only ground water systems affected by the ICR were those that served at least 50,000 people. These systems had to conduct treatment study applicability monitoring (by measuring TOC levels) and, in some
cases, studies to assess the effectiveness of granular activated carbon or membranes to remove DBP precursors. In addition, ground water systems serving at least 100,000 people had to obtain disinfectant and DBP occurrence and treatment data. EPA is still processing the ICR data, and has not used this information in developing the GWR.
4. Stage 1 Disinfectants/Disinfection Byproducts Rule
The Stage 1 Disinfectants/Disinfection Byproducts Rule (Stage 1 DBPR) (63 FR 69389; December 16, 1998) (US EPA, 1998e) sets maximum residual disinfection level limits for chlorine, chloramines, and chlorine dioxide, and MCLs for chlorite, bromate, and two groups of disinfection byproducts: total trihalomethanes (TTHMs) and haloacetic acids (HAA5). TTHMs consist of the sum of chloroform, bromodichloromethane, dibromochloromethane, and bromoform. HAA5 consist of the sum of mono-, di-, and trichloroacetic acids, and mono- and dibromoacetic acids. The rule requires water systems that use surface water or ground water to remove specified percentages of organic materials, measured as total organic carbon (TOC), that may react with disinfectants to form DBPs. Under the rule, precursor removal will be achieved through a treatment technique (enhanced coagulation or enhanced softening) unless a system meets alternative criteria.
The Stage 1 DBPR applies to all CWSs and non-transient NCWSs, both surface water systems and ground water systems, that treat their water with a chemical disinfectant for either primary or residual treatment. In addition, certain requirements for chlorine dioxide apply to transient water systems.
A ground water system that disinfects with chlorine or other chemical disinfectant must comply with the Stage 1 DBPR by December 2003. Sampling frequency will depend upon the number of people served. Ground water systems not under the direct influence of surface water that serve 10,000 people or greater must take one sample per quarter per treatment plant, and analyze for TTHMs and HAA5; systems that serve fewer than 10,000 people must take one sample per year per treatment plant during the month of warmest water temperature, and analyze for the same chemicals. Systems must monitor for chlorine or chloramines at the same location and time that they monitor for total coliforms. Additional monitoring for other chemicals is required for systems that use ozone or chlorine dioxide.
5. Underground Injection Control Program
In 1980, EPA established an Underground Injection Control (UIC) Program (US EPA, 1999g) to prevent injection practices which contaminate sources of drinking water. The UIC Program protects both underground sources of drinking water and ground water under the direct influence of surface water, which includes at least 41 percent of the streams and rivers in the U.S. during dry periods. Injection is a common and long-standing method of placing fluids underground for disposal, storage, replenishment of ground water, enhanced recovery of oil and gas, and mineral recovery. These fluids often contain contaminants. The EPA sets minimum requirements for effective State programs to ensure that injection practices, or “injection wells” as they are called in the UIC Program, are operated safely. EPA or the appropriate State regulatory agency may impose on any injection well, requirements for siting, construction, corrective action, operation, maintenance, monitoring, reporting, plugging and abandonment, and impose penalties on violators. The UIC Program regulations are designed to recognize varying geologic, hydrologic or historic conditions among different States or areas within a State.
The UIC Program regulations are found under Title 40 of the Code of Federal Regulations (CFR), Parts 124, and 144-148. Section 144.6 divides injection practices into five categories or classes of wells. Classes I, II, and III are wells which inject fluids beneath and away from aquifers used by ground water systems into confined geologic formations. These wells are associated with municipal or industrial waste disposal, hazardous waste or radioactive waste sites, oil and gas production, and extraction of minerals. Class IV and most of Class V are wells which inject contaminants, into or above aquifers which may be used by ground water systems. Class IV wells inject hazardous or highly radioactive wastes and are banned by all States and EPA. Class V wells include storm water and agricultural drainage wells, dry wells, floor drains and similar types of shallow disposal systems which discharge directly or indirectly to ground water, but in any case, must not endanger the ground water resources. However, Class V wells which may pose the greatest potential threat to ground water systems include poorly-designed or malfunctioning large-capacity septic tanks, leach fields and cesspools associated with solely sanitary wastewater disposal. Malfunctioning septic systems can result in the release of disease-causing microorganisms including enteric viral and bacterial pathogens to surface and ground water. Multi-family, commercial, manufacturing, recreational, and municipal facilities, particularly those located in unsewered areas sometimes dispose both sanitary waste and process wastewater containing harmful chemicals in Class V wells. This combination can increase the risk of contamination to aquifers used by ground water systems. Approximately half of the States have adopted primary enforcement authority for the regulation in whole or part and, therefore, have primary enforcement responsibility (primacy). State enforcement activities range from notices of improper activities to penalties and well closures. For those States which do not have primacy, the EPA Regional Offices perform the enforcement duties. (Note: the UIC Program does not regulate individual or single family residential septic systems and cesspools which inject solely sanitary wastewater) (40 CFR 144.1(g)(1)(2)). EPA has finalized banning large capacity cesspools in ground water source water protection areas (64 FR 234, December 7, 1999)(USEPA, 1999g).
6. Source Water Assessment and Protection Program (SWAPP) and the Wellhead Protection (WHP) Program
The Wellhead Protection Program (WHP Program) in SDWA section 1428 requires every State to develop a program that protects ground water sources of public drinking water. The intended result of the WHP Program are local pollution prevention programs that reduce or eliminate the threats of contamination to ground water sources of drinking water. To do this, States delineate wellhead protection areas (WHPA) in which sources of contamination are managed to minimize ground water contamination. WHPA boundaries are determined based on factors such as well pumping rates, time-of-travel of ground water flowing to the well, aquifer boundaries, and degree of aquifer protection by the overlying geology. These hydrogeologic characteristics have a direct effect on the likelihood and extent of contamination. Currently, 48 States and two territories have a WHP Program in place.
A new Source Water Assessment and Protection Program (SWAPP) was incorporated into SDWA section 1453 and requires each State to establish a SWAPP that describes how the State will: (1) Delineate source water
protection areas; (2) inventory significant contaminants in these areas; and (3) determine the susceptibility of each public water supply to contamination. This program builds upon the WHP Program; however, it addresses both ground water and surface water sources of public drinking water. The States' SWAPP were approved by EPA by November, 1999. Under the SWAPP, the State must complete source water assessments for all PWSs by November 6, 2001, although EPA may grant an extension to May 6, 2003. A summary of the results of the source water assessments must then be made available to the public in CWSs' Consumer Confidence Reports. The 1996 Amendments to the SDWA do not require States to protect water sources after the assessments are completed.
EPA seeks, in today's proposed GWR, to incorporate the States' SWAPP and WHP Programs into an overall Agency program for protecting ground water sources of public drinking water by encouraging States to use information gathered through these programs in site-specific sanitary surveys and hydrogeologic sensitivity assessments where appropriate.
C. Industry Profile—Baseline Information
1. Definitions and Data Sources
Outlined in the following section are data sources relied upon by the Agency to develop baseline information for the GWR. The baseline information is important to understanding how various regulatory options might affect risk reduction and the cost to small public water systems. The information shows that there is a large number of systems which solely utilize ground water, over 156,000. In addition, most of the ground water systems are small, with 97% serving 3,300 or fewer people. However, 55% of the people served by ground water sources get their drinking water from systems which serve 10,000 or more persons (one percent of the systems).
A public water system (PWS) is one that serves 25 or more people or has 15 or more service connections and operates at least 60 days per year. The following discussion of PWSs is based on the current definition of PWS (i.e., operating at least 60 days a year). A PWS can be publicly owned or privately owned. EPA classifies PWSs as community water systems (CWSs) or non-community water systems (NCWSs). CWSs are those that serve at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. NCWSs do not have year-round residents, but serve at least 15 service connections used by travelers or intermittent users for at least 60 days each year, or serving an average of 25 individuals for at least 60 days a year. NCWSs are further classified as either transient or non-transient. A non-transient non-community water system (NTNCWS) serves at least 25 of the same persons over six months per year (
e.g.
, factories and schools with their own water source). Transient non-community water systems (TNCWS) do not serve at least 25 of the same persons over six months per year (
e.g.
, many restaurants, rest stops, parks). The majority of ground water systems are NCWSs, with 60% (93,618) transient and 12% (19,322) non-transient. CWSs make up the remaining 28% (44,910) of all ground water systems. Although there are far more NCWSs, CWSs serve a far larger number of people.
Over 88 million people are served by CWSs that use ground water and 20 million people are served by NCWSs that use ground water. An overlap occurs because most people are served by both types of systems which may also include a combination of ground and surface water. For example, a person may be served by a surface water community water system (CWS) at home and by a ground water non-community water system (NCWS) at work.
EPA uses two primary sources of information to characterize the universe of ground water systems: the Safe Drinking Water Information System (SDWIS) and the Community Water System Survey (CWSS) (US EPA, 1997c). EPA's SDWIS contains data on all PWSs as reported by States and EPA Regions. This data reflects both mandatory and optional reporting components. States must report the location of the system, system type (CWS, TNCWS, or NTNCWS), primary raw water source (ground water, surface water or ground water under the direct influence of surface water), and violations. States may also report, at their option, type of treatment and ownership type. EPA does not have complete data on the discretionary items (such as treatment) in SDWIS for every system; this is especially common for NCWSs.
The second source of information, CWSS, is a detailed survey of surface and ground water CWSs conducted by EPA in 1995 (US EPA, 1997c). The CWSS includes information such as the number of system operators, revenues, expenses, treatment practices, source water protection measures, and capacity (
i.e.
, the amount of water the system is designed to deliver). The CWSS contains data from 1,980 water systems, and is stratified to represent CWSs across the U.S. Of the 1,980 water systems that were surveyed by CWSS, 1,020 are ground water systems; 510 are surface water systems; and 450 represent purchased water systems. Among the ground water systems represented, approximately 17% were from systems serving 100 persons or less; 20% were from systems serving 101-500 persons; 13% were from systems serving 501-1,000 persons; 14% were from systems serving 1,001-3,300 persons; 15% were from systems serving 3,301-10,000 persons; 10% were from systems serving 10,001-50,000 persons; and 11% were from systems serving 50,001 or more persons.
Baseline profile data for ground water systems from SDWIS and CWSS are summarized later. The data on system ownership, treatment, and operator information is from the CWSS.
2. Alternate Definition of “Public Water System” and the Problem of Short-Term Water Providers
EPA is not today proposing to change the definition of “public water supply,” nor proposing additional requirements for short-term water providers. If EPA decides to take either action, EPA will publish a proposal at a later date. However, EPA requests comment on the following issues.
A PWS is one that serves 25 or more people or has 15 or more service connections and operates at least 60 days per year. EPA requests comment on the definition of “public water system” specifically, shortening the time period within the regulatory definition (§ 141.2). Section 1401(4)(A) of the SDWA defines public water system as one that “regularly serves at least twenty-five individuals.” EPA by regulation defined the minimum time period that a system “regularly” serves as 60 days. See 40 FR 59566, December 24, 1975 for a discussion of the definition. The current definition applies after a minimum of 1,500 consumer servings (60 days multiplied by 25 individuals). However, some drinking water providers serve far more people during just a few events. For example, out-door public events may occur at a site just a few days a year but may draw thousands of people to each event. Such drinking water providers thus can affect the public health of a similar number of persons in a short period of time as a system that serves fewer people for a longer period. EPA wants to provide the same public health protection in these situations. Only
contaminants that cause adverse health effects through small volumes or short exposure (
e.g.,
acute contaminants such as microbes, nitrate and nitrite) are of concern at these short term events. Therefore, EPA is considering changing the definition of “public water system” by reducing the 60 day time frame to 30 days and including events drawing many people on one or just a few days, specifically by adding the phrase, “or serves at least 750 people for one or more days” to the end of the current definition of “public water system.” In other words, for short-term providers, the term “regularly serves” would be defined in terms of the number of persons served rather than days of service, but the minimum number of persons served would be equivalent to the number of servings for longer-term systems. EPA requests comment on this issue. Rather than the simple total of 750 (30 days times 25 people), should EPA include a minimum of persons served days (calculated by multiplying the average number of individuals served by the number of days the system serves water)? What should that number be? Should there be a sliding scale (
e.g.,
for a system operating one day and serving more than 10,000 consumers, and systems operating more than 30 days and serving 2,000 consumers)? EPA requests comments on defining/identifying systems, implementation, public notice, training, monitoring and record keeping and reporting issues for these systems if they were included.
As an alternate to changing the definition EPA is also considering and requesting comments on requiring under section 1431 of the SDWA or other appropriate authorities that transient water providers or other types of drinking water systems (including those not currently defined as public water systems) monitor for acute contaminants prior to providing water to the public and requiring that any such provider that finds acute contaminants at a level above the MCL not be allowed to serve drinking water until it is corrected. Currently, transient public water systems must currently monitor for total coliforms, nitrate and nitrite. In addition, transient public water systems using surface water or ground water under the direct influence of surface water must comply with the treatment technique requirements of the SWTR. EPA is also considering proposing requiring any non-community water system that is not operated year round monitor for: fecal coliforms, nitrate and nitrate, and that monitoring required to show treatment technique compliance (
e.g., Cryptosporidium
) no more than 30 days prior to beginning operation for that season. EPA requests comment on what time frame the monitoring should be completed prior to beginning operation (
i.e.
, 10 or 15 days).
3. Number and Size of Ground Water Systems
Nationally, SDWIS indicates that there are approximately157,000 public water systems that use ground water solely (SDWIS, 1997). Slightly more than 13,000 additional systems use surface water. SDWIS only describes any system that uses any amount of surface water as a surface water system. SDWIS therefore, does not have information on the number of systems that mix ground water and surface water. Under the SDWA and for purposes of the Regulatory Flexibility Act (RFA) analysis, EPA defines a small system as serving fewer than 10,000 people. According to SDWIS (1997), 96.6% of the 42,413 CWSs and virtually all of the NCWSs that use ground water serve fewer than 10,000 persons and thus are “small.” Collectively, 99% of systems serve fewer than 10,000 people. About 97% of the systems (152,555) serve 3,300 people or fewer (totaling over 31 million people nationally). The purpose of these requirements would be to prevent any endangerment to public health that might occur if these short-term, high volume providers dispense drinking water that is untested and potentially contaminated.
4. Location of Ground Water Systems
Ground water systems are located in all 50 States, many tribal lands and most United States territories. The number of ground water systems varies substantially by State. The largest numbers of ground water systems are in the States of Wisconsin, Michigan, Pennsylvania, New York and Minnesota. These five States, each with over 8,000 ground water systems, account for over 50,698 ground water systems—one third of the total number in the U.S. By contrast, Hawaii (126), Kentucky (287), Rhode Island (430), and the United States territories (<254) have the fewest ground water systems (See Table I-1).
5. Ownership of Ground Water Systems
For ground water CWSs, 36% are publicly operated, 35% are owned and operated by private entities whose primary business is providing drinking water, and 29% are ancillary water systems which are operated by entities whose primary business is not providing drinking water, but do so to support their primary business (
e.g.
, mobile home park operators). The distribution of ownership type, however, varies significantly with the size of the system. For example, over 90% of the ground water systems serving less than 100 people are privately owned or are ancillary systems. For systems serving over 100,000 people, only 16% are privately owned and none are ancillary systems.
Table I-1.—Number of Ground Water Systems and Populations Served by State and System Type
State/territory
CWSs
Number of systems
Population served
TNCWSs
Number of systems
Population served
NTNCWSs
Number of systems
Population served
Alabama
345
1,283,469
123
11,170
46
21,182
Alaska
511
342,722
906
97,647
0
0
American Samoa
10
48,692
0
0
0
0
Arizona
783
1,308,843
602
120,126
216
100,317
Arkansas
480
1,003,145
442
22,521
57
13,528
California
2,831
14,223,977
3,698
1,301,671
1,018
359,096
Colorado
548
927,917
1,061
153,454
133
34,884
Commonwealth of the Northern Marianas
30
50,769
7
620
6
3,039
Connecticut
537
311,771
3,360
2,980,181
641
121,664
Delaware
225
173,460
215
57,634
86
24,840
District of Columbia
0
0
0
0
0
0
Florida
2,019
13,132,468
3,660
304,865
1,119
286,055
Georgia
1,465
1,484,860
663
127,661
291
80,240
Guam
6
20,220
0
0
2
770
Hawaii
109
1,247,315
3
1,125
14
7,437
Idaho
658
579,778
1,033
125,873
265
68,195
Illinois
1,255
2,606,104
3,715
413,000
446
142,655
Indiana
806
1,826,820
2,984
327,229
693
158,102
Iowa
1,033
1,239,902
639
78,653
133
35,715
Kansas
601
747,169
110
4,481
67
23,602
Kentucky
124
271,630
83
9,374
80
21,620
Louisiana
1,211
2,707,805
482
115,804
234
88,070
Maryland
448
519,289
2,509
93,757
495
142,171
Massachusetts
360
1,396,430
863
209,476
229
67,650
Michigan
1,185
1,602,792
8,930
1,187,331
1,718
344,654
Minnesota
919
2,074,843
6,963
252,602
672
49,514
Mississippi
1,253
2,586,680
169
28,006
126
89,416
Missouri
1,194
1,638,152
1,040
138,894
227
76,360
Montana
554
267,597
1,011
140,745
215
38,504
Nebraska
616
811,112
584
22,241
189
26,219
Nevada
250
187,509
273
55,792
91
28,497
New Hampshire
621
262,371
1,012
181,949
421
77,505
New Jersey
516
2,339,500
2,955
346,484
1,009
274,758
New Mexico
600
1,235,920
506
74,256
149
38,101
New York
1,940
4,396,557
5,742
853,533
693
248,223
North Carolina
1,900
1,271,804
5,373
542,400
655
198,136
North Dakota
258
239,874
215
16,910
22
2,349
Ohio
1,129
3,555,876
3,545
533,921
1,116
276,441
Oklahoma
556
671,287
302
34,172
123
20,419
Oregon
677
622,157
1,390
233,477
332
67,531
Pennsylvania
1,788
1,567,696
7,017
922,336
1,251
480,328
Puerto Rico
207
623,958
4
765
43
36,426
Rhode Island
59
127,854
300
48,875
71
25,246
South Carolina
550
671,878
577
54,837
248
71,239
South Dakota
367
250,742
243
42,949
25
3,072
Tennessee
193
1,312,996
503
61,504
58
11,010
Texas
3,613
6,150,001
1,378
245,171
748
253,468
Tribes
685
330,466
0
0
82
20,833
Utah
335
583,506
439
79,371
52
20,969
U.S. Virgin Islands
0
0
0
0
0
0
Vermont
346
154,521
718
523,079
1
25
Virginia
1,199
584,779
1,911
443,920
772
312,422
Washington
2,092
2,299,340
1,498
283,735
287
70,009
West Virginia
297
304,888
644
47,313
182
39,318
Wisconsin
1,117
1,947,016
9,704
731,781
1,049
214,561
D. Effectiveness of Various Best Management Practices in Ground Water Systems
There are numerous sanitation practices, called best management practices (BMPs), to prevent, identify and correct contamination in a water supply. These practices relate to well siting, well construction, distribution system design and operations. Examples of BMPs that form a barrier to ground water contamination include drilling into a protected aquifer; siting a well away from sources of contamination; identifying and controlling contamination sources; and disinfection. BMPs that form a barrier to well contamination include well casing, well seals, and grouting the well. Distribution system BMPs include disinfection; maintaining positive pressure; flushing water mains; and adopting cross connection control programs. Surveillance BMPs such as sanitary surveys are conducted to identify weaknesses in the barriers.
EPA recognizes that BMPs can and do contribute significantly to the safety of drinking water; however, the effectiveness of each individual practice can be difficult to measure. Two studies, State Ground Water Management Practices—Which Practices are Linked to Significantly Lower Rates of Total Coliform Rule Violations? (US EPA, 1997d) and the Analysis of Best Management Practices for Community Ground Water Systems (Association of State Drinking Water Administrators, or ASDWA, 1998), were conducted to examine the relative effectiveness of BMPs in reducing microbial contamination of ground water systems. The EPA study compared BMP implementation at the State level to total coliform MCL violation rates of community ground water systems over a four year period. The ASDWA study compared BMP implementation to detections of both total and fecal coliform in community ground water systems over a two year period.
A third study was conducted by EPA, Ground Water Disinfection and Protective Practices in the United States, (US EPA, 1996a) to review State practices and requirements for the protection of drinking water that has ground water as its source.
1. EPA Report on State Ground Water Management Practices
In the EPA study, State Ground Water Management Practices—Which
Practices are Linked to Significantly Lower Rates of Total Coliform Rule Violations? (US EPA, 1997d), 12 BMPs were compared to the MCL violation rate for total coliform in community water systems by State. The 12 State BMPs were taken from the EPA report Ground Water Disinfection and Protective Practices in the United States (US EPA, 1996a). The study used total coliform MCL violation data in SDWIS for community water systems for Fiscal Years 1993 through 1996. In the study, pairwise and stepwise linear regression analyses were used to determine if there was a statistically significant difference in the TCR MCL violation rates between those States that practice a particular BMP and those that do not. From this perspective, BMPs associated with lower violation rates are considered effective. The 12 BMPs included in the study were well construction codes, well/pump disinfection requirements, sanitary surveys, disinfection of new/repaired mains, cross connection controls, operator certification, minimum setback distances, EPA approved State Wellhead Protection Programs, periodic flushing of mains, wellhead monitoring, hydrogeologic criteria, and disinfection.
Six of the 12 State management practices were unsuitable for pairwise analysis because these practices were present in nearly all States. Therefore, a comparison of TCR MCL violation rates in States with and without these practices could not be made. The BMPs for which analysis were not done were: well construction codes, well/pump disinfection requirements, sanitary surveys, disinfection of new/required mains, cross connection controls, and operator certification. However, these six management practices were evaluated as part of the 1998 Best Management Practices Survey conducted by ASDWA.
Using a pairwise statistical analysis, two of the remaining six practices, disinfection and hydrogeologic criteria, showed a significant statistical relationship (at a .01 and a .05 level of confidence, respectively) in lowering the statewide median TCR violation rates, with disinfection showing the strongest relationship. In this analysis, disinfection is defined as the maintenance of at least a chlorine residual or its equivalent at the entry point or in the distribution system. The report focused its analysis on disinfection practices among 20 States, comparing the 10 highest disinfecting States with the 10 lowest disinfection States. Specifically, the 10 States with the highest percentage of disinfected CWSs had an average MCL violation rate of 16% over the four year period, versus a 33% violation rate for the ten States with the lowest disinfection rates. States that require hydrogeologic criteria for well siting and construction decisions had significantly lower median MCL violation rates than States that do not use these criteria (15.4% vs. 24.6%). The other four practices, minimum setback distances from pollution sources, EPA approved Wellhead Protection Programs, periodic flushing of the distribution system, and wellhead monitoring, did not show a significant relationship in lowering TCR violation rates at the State level. The report does not provide information on the statistical significance of these results.
The four year time frame for the statistical analyses was chosen as a more accurate reflection of the effectiveness of statewide management practices given the high degree of variability in the TCR violation rate from year to year. Different trends emerge when annual rates are compared. There is not enough data to determine if the year to year variability, shown in the FY 96 data, correlates to a change in State management practices.
In a second analysis, stepwise linear regression was used on the six best management practices to further explain the variability among States in their reported TCR MCL violation rates. This analysis examines both the simultaneous effect of several BMPs on the State TCR MCL violation rate and evaluates which of the practices may explain the variability in the TCR violation rate among States. Ascertaining how much of the State-to-State variability can be explained by each of the practices is an important question given that the TCR requirements are the same for all States. The results of this analysis indicate that disinfection is the single largest factor in explaining the difference in the TCR violation rate among States. In general, the higher the rate of disinfection, the lower the rate of TCR MCL violations.
Uncertainties associated with this analysis were: (1) Whether a State's BMP requirements are fully implemented at the system level; (2) what effect the six State BMPs not analyzed had on violation rates; (3) the degree of voluntary implementation of BMPs; and (4) the effect of not including State practices required only under certain circumstances. Nonetheless, this data on State management practices indicates that there is a significant association between disinfection and a lower TCR MCL violation rate.
2. ASDWA Analysis of BMPs for Community Ground Water Systems
In the ASDWA study, The Analysis of Best Management Practices for Community Ground Water Systems (ASDWA, 1998), a working group selected 28 BMPs that represent four major areas of plant operations and developed and distributed a survey to all 50 State drinking water programs. Each State was asked to select eight systems in each of the three following categories: (1) Systems with no detections of total coliform; (2) systems with total coliform detections only; and (3) systems with both total coliform and fecal coliform (or
E. coli
) detections. For each system, the State was asked to report which of 28 BMPs listed were used by the system during a two year period (1995 and 1996). Thirty-six States responded to the survey, each completing up to 24 individual system surveys, providing data for 812 systems.
The survey results were analyzed using both descriptive statistics and two statistical models—pairwise and logistical regression. The descriptive statistics illustrate the characteristics of a system but cannot isolate the effect of a particular BMP from the effects of other BMPs. The statistical models were used to describe the relationship between implementation of individual or a group of BMPs and a reduction in total or fecal coliform detections.
A pairwise association analysis (
i.e.,
comparing a system that implements a particular BMP to one that does not) was used to determine if the use of a BMP reduced the percentage of positive total coliform samples. The analysis determined that a significant association was found between 21 of the 28 BMPs and systems with no total coliform detections. The two BMPs with the strongest correlation to fewer total coliform detections were correction of deficiencies identified by the sanitary survey and operator certification (ASDWA, 1998).
Using pairwise analysis for systems with fecal coliform (based only on those systems with at least one positive total coliform sample), the study found a significant association for eight of the twenty-eight BMPs. These eight BMPs include: system wells constructed according to State regulations, routine disinfection after well or pump repair, treatment for purposes other than disinfection, system maintaining acceptable pressure at all times, water distribution tanks are designed according to State requirements, systems are in compliance with State permitting requirements, systems have corrected deficiencies noted by the State
and system and operators receive routine training and education. According to the results, fewer BMPs are found to be significant in this analysis than the total coliform analysis. These results are expected given that the analysis of fecal coliform and
E. coli
only evaluate systems with at least one total coliform positive detection. Fecal coliform and
E. coli
tests are more specific to organisms found in human and animal feces, whereas total coliform tests indicate the presence of a broader class of enteric organisms. For this reason, there are fewer data points to model the association of BMPs with fecal coliform. Therefore, this analysis sets apart only the BMPs significant in preventing or eliminating fecal contamination.
Using the logistical regression technique, three BMPs were associated with a significant reduction of total coliform-positive samples: (1) Maintaining a disinfectant residual; (2) operator training; and (3) correcting deficiencies identified by the State as part of a sanitary survey. The two BMPs associated with a significant reduction of fecal coliform/
E. coli
-positive samples were treatment for purposes other than disinfection,
e.g.,
iron removal, and operator training. Another analysis was constructed using Logit models for four categories of BMPs to consider the effects of BMPs in groups rather than individually. Out of the four categories (Source Protection/Construction, Treatment, Distribution System, and Management and Oversight), the Management and Oversight category showed the most significant association with reduced coliform detections.
The ASDWA survey also evaluated the effectiveness of BMPs with regard to system size. For systems serving less than 500 persons, correction of deficiencies identified by the State, and regular training and education of operators were the most significant in reducing microbial contamination. Routine disinfection after well or pump repair had the greatest significance among systems serving between 501 and 3,300 persons, while maintaining a disinfection residual had the greatest significance among systems serving between 3301 and 10,000 persons.
Overall, this study found that the percentage of systems implementing BMPs is highest among systems with no total coliform detections. In addition, systems that routinely educate and train their operators were more likely to implement other BMPs than systems with no regular training. Similarly, those systems that practice disinfection (contact time or maintain disinfection residual) were more likely to implement other BMPs than systems that do not disinfect. Observations about the implementation of BMPs suggests that many BMPs are interrelated, therefore, it is difficult to isolate the effect of an individual BMP.
3. EPA Report on Ground Water Disinfection and Protective Practices
The purpose of the EPA study, Ground Water Disinfection and Protective Practices in the United States, (US EPA, 1996a) was to compile and assess State regulations, guidance, codes, and other materials pertaining to protection of public health from microbial contamination in public water systems using ground water.
The information compiled included the following:
• Wellhead/ground water protection information;
• Ground water disinfection requirements;
• Well siting and construction requirements/guidelines;
• Sanitary survey requirements/guidelines;
• Distribution system protection requirements/guidelines; and
• Operator certification requirements.
The study found that there are widespread, but diverse requirements for the protection of drinking water that has ground water as its source. Few of these protective practices are used by all States and there is a variety of interpretations of the same practice. For example, 47 States specify minimum setback distances from sources of microbial contamination but show a wide range of setback distances for the same type of contaminant source; 49 States drinking water programs require disinfection of some sort, but when and where disinfection is required varies considerably; and of the 48 States that have well construction codes, 21 States do not require consideration of hydrogeological criteria in the approval of the siting of a well.
Overall, the study found that although many States appear to require similar BMPs, the nature, scope, and detail of these requirements varies considerably at the national level.
E. Outreach Activities
1. Public Meetings
As part of the 1986 amendments to the Safe Drinking Water Act (SDWA) Section 1412(b)(8), Congress directed EPA to promulgate a national primary drinking water regulation (NPDWR) requiring disinfection as a treatment technique for all public water systems, including those served by surface water and ground water. In 1987, EPA began developing a rule to cover ground water systems. This effort included a preliminary public meeting on the issues in 1990 (see 55 FR 21093, May 22, 1990, US EPA, 1990a). In 1992, EPA circulated a strawman draft for comment (see 57 FR 33960, July 31, 1992) (US EPA, 1992a).
From 1990 to 1997, EPA conducted technical discussions on a number of issues, primarily to establish a reasonable means of establishing whether a ground water source was vulnerable to fecal contamination and thus pathogens. This effort was accomplished through
ad hoc
working groups during more than 50 conference calls with participation of EPA Headquarters, EPA Regional offices, States, local governments, academicians, and trade associations. In addition, technical meetings were held in Irvine, California in July 1996, (US EPA, 1996c) and in Austin, Texas in March 1997 (US EPA, 1997e).
The SDWA was amended in August 1996, and as a result, several statutory provisions were added establishing new drinking water requirements. Specifically, Congress required under section 1412(b)(8) that EPA develop regulations specifying the use of disinfectants for ground water systems “as necessary.” These amendments established a new regulatory framework that required EPA to set criteria for States to determine whether ground water systems need to disinfect. In December 1997, EPA held its first of a series of stakeholder meetings to present a summary of the findings resulting both from technical discussions held since 1990 and from information generated by internal EPA working groups with the intention of developing disinfection criteria for ground water systems.
EPA held a preliminary Ground Water Rule meeting on December 18 and 19, 1997, in Washington, DC for the purpose of engaging all interested stakeholders in the analysis of data to support the GWR. The two day meeting covered discussions on the implications of the data, solicited further data from stakeholders, and reviewed EPA's next steps for rule development, data analysis and stakeholder involvement.
Since December 1997, EPA has held GWR stakeholder meetings in Portland, OR, Madison, WI, Dallas, TX, Lincoln, NE, and Washington, DC along with three early involvement meetings with State representatives. In addition, EPA has received valuable input from small system operators as part of an Agency outreach initiative under the Small Business Regulatory Enforcement Fairness Act. See section VI for more
information on the SBREFA process. Taken together, these stakeholder meetings have been crucial both in obtaining feedback and getting additional information as well as in guiding the Agency's consideration and development of different regulatory components.
The Agency's goal in developing the GWR is to reduce the risk of illness caused by microbial contamination in public water systems relying on ground water. The series of GWR stakeholder meetings were beneficial in assisting EPA in understanding how State strategies fit together as part of a national strategy. For more information see the (Stakeholders Meeting Summary, Resolve, July 27, 1998).
Portland, OR, GWR Stakeholder Meeting
There were four different regulatory approaches presented in the first of a series of stakeholder meetings held in Portland, OR, in May 1998: the Barrier Assessment Approach, the Existing State Practices Approach, the Setback Approach, and the Checklist Approach (Stakeholder Meetings Summary, Resolve, July 27, 1998). All approaches address, to varying degrees, three main areas: minimum program requirements or baseline measures, identification of high risk wells, and corrective action. Discussions on the potential approaches centered around determining triggers that could place a well in a high priority category and which minimum set of BMPs should be implemented at high risk wells.
Madison, WI GWR Stakeholder Meeting
There were three approaches presented in a June 9, 1998, GWR stakeholder meeting held in Madison, WI: Status Quo Approach, Baseline Approach, and Disinfection Approach. Regulatory approaches were revised in response to stakeholder input from the earlier GWR stakeholder meetings, representing a continuum of requirements, from Existing Status Quo to mandatory disinfection for all ground water systems. EPA emphasized that existing occurrence data does not appear to support mandatory disinfection across the board, but that the Agency would still appreciate stakeholder input on a range of options. The approaches presented were based on monitoring, inspections, BMPs and disinfection.
Dallas, TX GWR Stakeholder Meeting
A third GWR meeting on June 25, 1998 in Dallas, TX, provided slight modifications to the regulatory approaches, but for the most part the regulatory approach remained unchanged from the Madison meeting held in early June. EPA continued to emphasize the need to identify and strengthen the potential barriers to contamination. Among the three approaches, (Status Quo, Progressive and Universal Disinfection) the Progressive approach was considered the more viable regulatory option to ensure public health protection among public water systems.
Early Involvement Meetings
ASDWA held three early involvement meetings (EIMs) on the GWR. The first EIM followed the May 5, 1998 stakeholder meeting in Portland, OR. The second EIM meeting was held in Washington, DC on July 14 and 15, 1998 and the third meeting was held in Chicago, IL on April 7 and 8, 1999. Representatives from 12 States, four EPA Regions, ASDWA and EPA Headquarters participated in the May 6 and 7, 1998 meeting in Portland, OR. The second EIM involved 10 State representatives, ASDWA, and EPA Headquarters. The third EIM included one Region, seven State representatives, ASDWA and EPA Headquarters. The purpose of the meetings was to review the findings and comments from the stakeholder meetings and to work together to further refine GWR regulatory options. EPA and States discussed a range of issues including risk, exposure, strategies for identifying high risk systems, occurrence data, and regulatory implementation barriers.
2. Review and Comment of Preliminary Draft GWR Preamble
EPA developed a preliminary draft preamble reflecting a wide range of input from numerous stakeholders across the country including four public meetings, three EIMs with State representatives, in addition to valuable input received from small system operators as part of the outreach process established by SBREFA.
To facilitate the rule development process, the preliminary draft preamble was made available to the public via the Internet through EPA's website site on February 3, 1999. Approximately 300 copies were mailed to participants of the public meetings or to those who requested a copy. EPA welcomed any comments, suggestions, or concerns reviewers had on either the general direction or the technical basis of the proposal. EPA closed the email box on February 23, 1999 and continued to receive written comments through the mail through March 17, 1999. Because this was an informal process, EPA did not prepare a formal response to the comments. Nonetheless, the Agency carefully reviewed and evaluated all comments and technical suggestions and greatly appreciated the input and feedback provided by these outreach efforts.
Eighty individual comment letters were received. Commenters included: State and local government representatives, trade associations, academic institutions, businesses and other Federal agencies. Microbial monitoring received the most individual comments. Sanitary survey, sensitivity assessment and treatment issues were next, respectively.
II. Public Health Risk
The purpose of this section is to discuss the health risk associated with pathogens in ground waters. More detailed information about pathogens may be found in three EPA drinking water criteria documents for viruses (US EPA 1985a; 1999b; 1999c), three EPA criteria documents for bacteria (US EPA 1984a, b; 1985b) and the GWR Occurrence and Monitoring Document (US EPA, 1999d). EPA requests comment on all the information presented in this section, and the potential impact of proposed regulatory provisions on public health risk.
A. Introduction
Enteric viral and bacterial pathogens are excreted in the feces of infected individuals. Many bacterial pathogens can infect both humans and animals. Bacterial pathogens that infect humans can also be found in animal feces. In contrast, enteric viruses that are human pathogens generally only infect humans, and thus are only found in human feces. These organisms are able to survive in sewage and leachate derived from septic tanks (septage) and sewer lines. When sewage and septage are released into the environment, they are a source of fecal contamination. Fecal contamination is a very general term that includes all of the organisms found in feces, both pathogenic and non-pathogenic, as well as chemicals.
Fecal contamination of ground water can occur by several routes. First, fecal contamination can reach the ground water source from failed septic systems, leaking sewer lines, and from land discharge by passage through soils and fissures. Twenty-five million households in the United States use conventional onsite wastewater treatment systems, according to the 1990 Census. These systems include systems with septic systems and leach fields. A national estimate for failure rates of these systems is not available; however, a National Small Flows Clearinghouse survey reports that in
1993 alone, 90,632 failures were reported. (USEPA, 1997f). The volume of septic tank waste, alone, that is released into the subsurface has been estimated at one trillion gallons per year (Canter and Knox, 1984). This contamination may eventually reach the intake zone of a drinking water well. Second, fecal contamination from the surface may enter a drinking water well along the casing or through cracks in the sanitary seal if it is not properly constructed, protected, or maintained. Third, fecal contamination may also enter the distribution system when cross connection controls fail or when negative pressure in a leaking pipe allows contaminant infiltration.
Biofilms in distribution systems may harbor bacterial pathogens, especially the opportunistic pathogens that cause illness primarily in individuals with weakened immune systems. These bacterial pathogens may have entered the distribution system as part of fecal matter from humans or other animals. Biofilms may also harbor viral pathogens (Quignon
et al.,
1997), but, unlike some bacterial pathogens, viruses do not grow in the biofilm. However, a biofilm may protect the viruses against disinfectants and help them survive longer.
Although not the basis for today's proposed rule, there are additional waterborne pathogens that EPA is currently evaluating. These include bacterial pathogens that may be free-living in the environment, and thus not necessarily associated with fecal contamination. These pathogens include
Legionella
(causes Legionnaires Disease and Pontiac Fever),
Pseudomonas aeruginosa,
and
Mycobacterium avium-intracellulare
. Many of these bacteria can colonize pipes of the distribution system and plumbing systems and may play a role in causing waterborne disease that is currently under study. EPA recognizes the potential risk of such organisms, but believes that more research needs to be conducted before they can be considered for regulation. Also, the Agency is aware that
Giardia
and
Cryptosporidium
have occurred in ground water systems (GWSs) (Hancock
et al.
, 1998), causing outbreaks in such systems (Solo-Gabriele and Neumeister, 1996). However, by definition under § 141.2 ground waters with significant occurrence of large diameter pathogens such as
Giardia
or
Cryptosporidium
are considered ground water under the direct influence of surface water and are already subject to the SWTR and IESWTR. The Agency is also not addressing in the GWR the important issue of toxic or carcinogenic chemicals in the GWR. This issue is instead covered in other regulations that address chemicals.
In order to assess the public health risk associated with drinking ground water, EPA has evaluated information and conducted analysis in a number of important areas discussed in more detail later. These include: (1) Recent waterborne disease outbreak data; (2) dose-response data and other health effects data from a range of pathogens; (3) occurrence data from ground water studies and surveys; (4) an assessment of the current baseline ground water protection provided by existing regulations; and (5) an analysis of risk.
B. Waterborne Disease Outbreak Data
The purpose of this section is to present a detailed review of waterborne disease outbreaks associated with ground waters. Outbreak characterization is useful for indicating relative degrees of risk associated with different types of source water and systems.
The Centers for Disease Control and Prevention (CDC) maintains a database of information on waterborne disease outbreaks in the United States. The database is based upon responses to a voluntary and confidential survey form that is completed by State and local public health officials. CDC defines a waterborne disease outbreak as occurring when at least two persons experience a similar illness after ingesting a specific drinking water (Kramer
et al.,
1996). Data from the CDC database appears in Tables II-1, II-2, II-3, and II-4.
The National Research Council strongly suggests that the number of identified and reported outbreaks in the CDC database (both for surface and ground waters) represents a small percentage of actual waterborne disease outbreaks (Safe Water From Every Tap, National Research Council, 1997; Bennett
et al.,
1987; Hopkins
et. al.,
1985 for Colorado data). In practice, most waterborne outbreaks in community water systems are not recognized until a sizable proportion of the population is ill (Perz
et al.,
1998; Craun 1996), perhaps 1% to 2% of the population (Craun, 1996). Some of the reasons for the lack of recognition and reporting of outbreaks, most of which were noted by the National Research Council (1997), are as follows:
• Some States do not have active disease surveillance systems. Thus, States that report the most outbreaks may not be those in which the most outbreaks occur.
• Even in States with effective disease surveillance systems, health officials may not recognize the occurrence of small outbreaks. In cities, large outbreaks are more likely to be recognized than sporadic cases or small outbreaks in which ill persons may consult different physicians. Even so, health authorities did not recognize the massive outbreak (403,000 illnesses) of waterborne cryptosporidiosis that occurred in Milwaukee, WI, in 1993, until the disease incidence was near or at its peak (MacKenzie
et al.,
1994). The outbreak was recognized when a pharmacist noticed that the sale of over-the-counter diarrheal medicine was very high and consequently notified health authorities.
• Most cases of waterborne disease are characterized by general symptoms (diarrhea, vomiting,
etc.
) that cannot be distinguished from other sources (
e.g.,
food).
• Only a small fraction of people who develop diarrheal illness seek medical assistance.
• Many public health care providers may not have sufficient information to request the appropriate clinical test.
• If a clinical test is ordered, the patient must comply, a laboratory must be available and proficient, and a positive result must be reported in a timely manner to the health agency.
• Not all outbreaks are effectively investigated. Outbreaks are included in the CDC database only if water quality and/or epidemiological data are collected to document that drinking water was the route of disease transmission. Monitoring after the recognition of an outbreak may be too late in detecting intermittent or a one-time contamination event.
• Some States do not always report identified waterborne disease outbreaks to the CDC. Reporting outbreaks is voluntary.
• The vast majority of ground water systems are non-community water systems (NCWSs). Outbreaks associated with NCWSs are less likely to be recognized than those in community water systems because NCWSs generally serve nonresidential areas and transient populations.
There is also the issue of endemic waterborne disease. Endemic waterborne disease may be defined as any waterborne disease not associated with an outbreak. A more precise definition is the normal level of waterborne disease in a community. Under this definition, an outbreak would represent a spike in the incidence of disease. Based on this definition, the level of endemic waterborne disease in a community may be quite high. For example, 14%-40% of the normal gastrointestinal illness in a community in Quebec was associated
with drinking treated water from a surface water source (Payment
et al.,
1997). Significant levels of endemic disease could also be associated with ground waters. Because endemic waterborne disease may be a significant and substantially preventable source of health risk, under the directive of the 1996 SDWA Amendments, EPA is jointly pursuing with CDC a multi-city study of waterborne disease occurrence in an effort to provide greater understanding of this risk. EPA believes that some meaningful percentage of the nationwide occurrence of endemic waterborne disease is in ground water systems (GWSs). EPA believes that the prudent policy of prevention embodied in this proposal with regard to identified sources of substantial microbial risk to GWSs gains further justification as a counter to the endemic occurrence of waterborne disease. EPA solicits comment and any data that can increase knowledge of these endemic risks, in particular any studies on such risk in GWSs.
CDC Waterborne Disease Outbreak Data
Outbreak data collected by CDC are presented in Tables II-1, II-2 , II-3, and II-4. Table II-1 provides outbreak data for all public water systems (surface and ground water). Table II-2 shows sources of waterborne disease outbreaks for GWSs. Table II-3 identifies the etiology of waterborne outbreaks in GWSs. Table II-4 shows causes associated with waterborne disease outbreaks and illnesses in GWSs.
According to CDC, between 1971 and 1996 a total of 643 outbreaks and 571,161 cases of illnesses were reported (see Table II-1); however, the total includes 403,000 cases from a single surface water outbreak caused by
Cryptosporidium
in Milwaukee, WI in 1993. Excluding the Milwaukee outbreak from the data set, 642 outbreaks and 168,161 cases of illness were reported during the same period of time. Ground water sources were associated with 371 (58%) of the total outbreaks and 16% of the associated illness (54% of the illness if the Milwaukee outbreak is excluded). In comparison, surface water sources were associated with 216 (33%) of the total outbreaks and 82% of the associated illness (40% of the illness if the Milwaukee outbreak is excluded). Although the data in Table II-1 indicate that NCWSs using ground water had twice as many outbreaks as CWSs using ground water, this may reflect the fact that there are over twice as many NCWSs as CWSs.
The outbreak data indicate that the major deficiency in ground water systems was source water contamination—either untreated or inadequately treated ground water (see Table II-2). Contaminated source water was the cause of 86% of the outbreaks in ground water systems. Contamination due to source water was the cause of 68% of the outbreaks for CWSs, while for NCWSs it was 92%. Distribution system deficiencies were associated with 29% of the outbreaks in CWSs and in five percent of the NCWSs.
Of the 371 outbreaks in ground water systems, 91 (25%) were associated with specific viral or bacterial pathogens, while 22 (6%) were associated with chemicals (see Table II-3). Etiologic agents were not identified in 232 (63%) outbreaks. The diversity of disease agents is similar to that of surface water, with a variety of protozoa, viruses, and bacteria. As stated previously, a ground water with
Cryptosporidium
or
Giardia
is, by definition, a “ground water under the direct influence of surface water”, and is thus subject to the microbial treatment requirements of a surface water system (
i.e.,
SWTR or IESWTR). According to CDC's data, bacterial pathogens were responsible for more outbreaks (57) than were viral pathogens (34). However, EPA suspects that many, perhaps a majority, of the outbreaks where an agent was not determined (232) were virus-caused, given the fact that it is generally more difficult to analyze for viral pathogens than bacterial pathogens. The fecal bacterial pathogen,
Shigella,
caused far more reported outbreaks (eight percent) than any other single agent.
Table II-4 shows outbreak data since 1991, the year in which the TCR became effective. Untreated ground water and inadequate treatment were collectively associated with 73% of the outbreaks in ground water systems between 1991-1996.
Large outbreaks are rarely associated with ground water systems because most ground water systems are small. However, one large outbreak occurred in Georgetown, TX, in 1980 (Hejkal
et al.,
1982) where 7,900 people became ill. Coxsackievirus and hepatitis A virus were found in the raw well water in a karst hydrogeologic setting; the outbreak was the result of source water contamination. Another occurred in 1965, in Riverside, CA, where about 16,000 illnesses resulted from exposure to
Salmonella typhimurium
in the source water (Boring, 1971).
Most of the outbreaks were caused by agents of gastrointestinal illness. Normally, the disease is self-limiting and the patient is well within one week or less. However, in some cases, deaths have occurred. In 1989, four deaths (243 illnesses) occurred in Cabool, MO, as a result of distribution system contamination by
E. coli
0157:H7 (Swerdlow
et al.,
1992; Geldreich
et al.,
1992). In 1993, seven deaths (650 illnesses) occurred in Gideon, MO, as a result of distribution system contamination by Salmonella typhimurium (Angulo, 1997). Both cases involved ground water systems. Waterborne disease in ground water systems has also caused serious illness such as hemolytic uremic syndrome (six reported cases in two outbreaks), which includes kidney failure, especially in children and the elderly. Two cases of hemolytic uremic syndrome were reported during the Cabool outbreak, the affected individuals being three and 79 years of age. Deep wells are not immune from contamination; for example, an outbreak of gastroenteritis caused by the Norwalk virus (900 illnesses) was associated with a 600-foot well (Lawson
et al.,
1991).
Collectively, the data indicate that outbreaks in ground water systems are a problem and that source contamination and inadequate treatment (or treatment failures) are responsible for the great majority of outbreaks. The outbreaks are caused by a variety of pathogens, most of which cause short term gastrointestinal disease.
Table II-1.—Comparison of Outbreaks and Outbreak-Related Illnesses From Ground Water and Surface Water for the Period 1971-1996
1
2
Water source
Total outbreaks
1
Cases of
illnesses
Outbreaks in CWSs
Outbreaks in NCWSs
Total CWS
4
Total NCWS
4
Ground
371 (58%)
90,815 (16%)
113
258
43,908
112,940
Surface
216 (33%)
469,721
2
(82%)
142
43
10,760
2,848
Other
56 (9%)
10,625 (2%)
29
19
All Systems
3
643 (100%)
571,161 (100%)
284
320
54,668
115,788
1
Modified from Craun and Calderon, 1994, plus 1995-1996 data.
2
Includes 403,000 cases of illness from a single outbreak in Milwaukee, Wisconsin, 1993.
3
Includes outbreaks in CWSs + NCWSs + Private wells.
4
Safe Drinking Water Information System, 1998.
Table II-2.—Sources of Waterborne Disease Outbreaks, Public Ground Water Systems, 1971-1996
1,2
.
Type of contamination
Total
Percent of total
CWSs
Percent of total
NCWSs
Percent of total
Source
274
86
53
68
221
92
Untreated
150
47
20
26
130
54
Disinfected
122
38
31
40
91
38
Filtered
2
1
2
3
0
0
Distribution System
35
11
23
29
12
5
Unknown Cause
9
3
2
3
7
3
Total
318
100
78
100
240
100
1
Source water could not be identified for 29 CWSs and 19 NCWSs with outbreaks, and thus these systems are not included in the table.
2
Excludes outbreaks caused by protozoa and chemicals.
Table II-3.—Etiology of Outbreaks in Ground Water Systems, 1971-96, CWSs and NCWSs
Causative agent
Outbreaks
Percent
Undetermined
232
63
Chemical
22
6
Giardia
1
21
6
Cryptosporidium
1
4
1
E. histolytica
1
<1
Total Protozoa
26
7
Hepatitis A
18
5
Norwalk Agent
16
5
Total Virus
34
9
Shigella
30
8
Campylobacter
10
3
Salmonella,
non-typhoid
10
3
E. coli
4
1
S. typhi
1
<1
Yersinia
1
<1
Plesiomonas shigelloides
1
<1
Total Bacteria
57
15
Total
371
100
1
Ground waters with
Giardia
and
Cryptosporidium
are regulated under the SWTR and IESWTR. These systems would likely not be considered ground water systems for purposes of this rule.
Table II-4.—Causes of Outbreaks in Ground Water Systems, 1991-1996
Cause
Number of outbreaks
Cases of
illness
Percent of outbreak-related illnesses
Untreated Ground Water
18
2924
51
Distribution System Deficiency
6
944
17
Treatment Deficiency
17
1260
22
Miscellaneous, Unknown Cause
3
568
10
Total
44
5696
100
1
Excludes protozoa and chemicals.
C. Ground Water Occurrence Studies
The purpose of this section is to present data on the occurrence of waterborne pathogens and indicators of fecal contamination in ground water supplying PWS wells. These data are important to GWR development because they provide insight on: (1) The extent to which ground water may be contaminated; (2) possible fecal indicators for source water monitoring under the GWR; and (3) a national estimate of ground water pathogen occurrence. In addition, determining the occurrence of microbial contaminants in ground water sources of drinking water is necessary to yield a quantified national estimate of public health risk.
EPA has reviewed data from13 recent or on-going studies of pathogen and/or fecal indicator occurrence in ground waters that supply PWSs. While most of these studies were not designed to yield a nationally representative sample of ground water systems, one of the studies (Abbaszadegan
et al.,
1999, or the “AWWARF study”) was later expanded to include a nationally representative range of hydrogeologic settings. This study was used as the basis of EPA's quantitative assessment of baseline risk from viral contamination of ground water, which is also a component of the quantitative benefits assessment for the proposed rule. Short narratives on each of the studies are provided in the next sections. The study design and results for each study are summarized in Table II-6, at the end of the narratives. The Agency decided not to combine the data from these studies, because of the different method protocols and scopes.
Each occurrence study investigated a combination of different pathogenic and/or indicator viruses and bacteria. Indicator viruses and bacteria may be non-pathogenic but are associated with fecal contamination and are transmitted through the same pathways as pathogenic viruses and bacteria. The samples analyzed in each study were tested for viral pathogens such as enteroviruses (a group of human viruses also referred to as “total cultureable viruses”) and/or bacterial pathogens such as
Legionella
and
Aeromonas.
Several studies used the polymerase chain reaction (PCR) as part of the method for determining the presence of pathogenic viruses. Bacterial indicators of fecal contamination tested included enterococci (or fecal streptococci, which are closely related), and fecal coliforms (or
E. coli,
which is closely related), and
Clostridium perfringens.
Most studies tested for total coliforms, which are not considered a direct fecal indicator since they also include coliforms that live in soil. Viral indicators of fecal contamination were all bacteriophage, which are viruses that infect bacteria. Among the bacteriophage tested were somatic coliphage and/or male-specific coliphage, both of which infect the bacterium
E. coli.
Bacteroides phage were tested in two studies and
Salmonella
phage in one study.
While this section presents a summary of each study, a more detailed explanation of one study (Abbaszadegan
et al.
, 1999) (AWWARF Study) is provided, as it is the broadest study in scope. The hydrogeology of individual wells is mentioned in addition to the microbial results, because EPA considers hydrogeology an important factor in source water contamination. Hydrogeology is discussed in greater detail in section III.B.
1. Abbaszadegan et al. (1999) (AWWARF Study)
Of the 13 studies, the AWWARF study sampled the largest number of wells, examined the widest array of well and system characteristics, and tested sites in 35 States across the U.S., located in hydrogeologic settings representative of national hydrogeology. The objectives of the AWWARF study were to: (1) Determine the occurrence of virus contamination in source water of public ground water systems; (2) investigate water quality parameters and occurrence of microbial indicators in ground water and possible correlation with human viruses; and (3) develop a statistically-based screening method to identify wells at risk of fecal contamination. A summary of AWWARF results are presented in Tables II-5 and II-6.
Many of the initial sites were selected to evaluate the effectiveness of a method based on the reverse-transcriptase, polymerase chain reaction (RT-PCR) technique to detect pathogenic viruses in ground water. Sites for this portion of the study were selected based on the following criteria: (1) Ground water sites with high concentrations of minerals, metals, or TOC; (2) sites with a previous detection of any virus or bacteria in the ground water source; (3) sites with potential exposure to contaminants due to agricultural activities near the well, industrial activities near the well, or septic tanks near the well; and (4) sites with different pH values, temperatures, depths, production capacities and aquifer types. Sites were selected for the virus occurrence project based upon their geological characteristics to balance out the range of geologies so that the sites in aggregate more closely matched the national geologic profile of ground water sources. Sites for the virus occurrence study were selected from an initial mailing to 500 utilities that currently disinfect their water; 160 utilities with 750 wells volunteered to be included in the study. In total, 448 wells were sampled for the study. AWWARF excluded sites from the investigation if: (1) It was known to be under the influence of surface water; (2) the well log records were not available; or (3) it was considered poorly constructed.
EPA subsequently compared nitrate concentrations from a national database of nitrate concentrations in ground water (Lanfear, 1992) with nitrate data measured in the AWWARF study wells. The purpose of the comparison was to determine if there was any statistically significant difference between the nitrate levels in the AWWARF wells as compared with the national distribution of nitrate concentration data. Nitrate was chosen for this comparison because there is a large, national database available. Each data set contained 216 samples selected so that proportionately, wells of equal depth were analyzed in each comparison. The national data were selected randomly from a database of more than 100,000 wells; all available AWWARF data were used. In analyzing the data, EPA noted that the national data is biased by multiple sampling of many shallow monitoring wells in farming regions leading to a few wells having exceptionally high nitrate levels. In order to minimize the impact of these wells on the analysis, EPA chose a small random subset comparable in size to the sample in the AWWARF study. Thus, the data are not directly comparable with PWS wells. Census data were used to divide the national nitrate database into urban and rural components. The analysis showed that the AWWARF wells had nitrate concentrations that were not significantly different from the national data or from the urban and rural components. Thus, using nitrate concentration as a surrogate, EPA concludes that, by this measure, the AWWARF wells are nationally representative.
All samples were collected by the systems. AWWARF provided a sample kit containing all needed equipment and a video illustrating the details of appropriate sampling and storage procedures. A total of 539 samples were collected from 448 sites in 35 States. The preliminary results indicate that of the 448 wells sampled, about 64% were located in unconsolidated aquifers, 27% in consolidated aquifers including consolidated sedimentary strata, and 9% in unknown geology. Unconsolidated aquifers are made of
loosely packed (uncemented) particles, such as sand grains or gravel, while consolidated aquifers are comprised of compacted (cemented) particles or crystalline rock (
e.g.,
granite, limestone). As discussed further in section III.B., the degree and type of consolidation may affect the transport of pathogens from a source of fecal contamination to the well. The percentages of sites sampled from these geologic settings are similar to those of national ground water production from unconsolidated and consolidated hydrogeologic settings (modified by AWWARF, from United States Geological Survey (USGS) Circular 1081, 1990). The data indicate that 174 sites (39%) were within 150 feet of a known sewage source, and an additional 127 sites (28%) were within 550 feet of a known sewage source. There is no comparable data on the distribution nationally of wells relative to sewage sources. EPA notes however, that the proximity to these sources is not inconsistent with State standards across the country. For example, 41 States have setback distances (the minimum distance between a source of contamination and a well) that are less than or equal to 100 feet for sources of microbial contaminants. Only five States appear to require setback from all sewage sources of more than 200 feet. The preliminary results also indicated that a total of 25 sites were sampled more than once. Most sites were from systems that serve greater than 3,300 people, and almost all systems maintain a disinfectant residual.
In the study, systems collected at least 400 gallons (1,512 liters) of water and concentrated it using a filter-adsorption and elution method. The concentrated samples were then sent to the researchers for analysis. The presence of enteroviruses was determined by two procedures: a cell culture assay and a procedure using the RT-PCR technique. The RT-PCR technique was also used to determine the presence of hepatitis A virus, rotavirus, and Norwalk virus. The researchers also tested each well for total coliforms, enterococci,
Clostridium perfringens,
somatic coliphage, and male-specific coliphage to establish their relationship with enterovirus and to get a better indication of the percentage of fecally contaminated wells.
Preliminary results indicated that fecal contamination occurs in a subset of PWS wells (see Table II-5). The investigators detected pathogenic viruses, either by cell culture or RT-PCR analyses, in a significant percentage of samples.
Table II-5.—Preliminary Results of AWWARF Study
Assay
Percent of wells positive (number positive/samples analyzed)
Enteroviruses (cell culture)
4.8% (21/442)
Bacterial Indicators
15.1%
Total coliforms
9.9% (44/445)
enterococci
8.7% (31/355)
Clostridium perfringen
spores
1.8% (1/57)
Coliphage Indicators
20.7%
Male-specific coliphage (
Salmonella
WG-49 host)
9.5% (42/440)
Somatic coliphage (
E. coli
C host)
4.1% (18/444)
Somatic and male-specific coliphage (
E. coli
C-3000 host)
10.8% (48/444)
PCR
31.5%
Norwalk viruses (PCR)
0.96% (3/312)
Enteroviruses (PCR)
15.9% (68/427)
Rotaviruses (PCR)
14.6% (62/425)
Hepatitis A viruses (PCR)
7.2% (31/429)
2. Lieberman et al., (1994, 1999) (EPA/AWWARF Study)
The study objectives included the following: (1) develop and evaluate a molecular biology (PCR) monitoring method; (2) obtain occurrence data for human enteric viruses and
Legionella
(a bacterial pathogen) in ground water; and (3) assess the microbial indicators of fecal contamination. These objectives were accomplished by sampling vulnerable wells nominated by States to confirm the presence of fecal indicators (Phase I) and then choosing a subset of these for monthly sampling for one year (Phase II).
In Phase I, well vulnerability was established using historical microbial occurrence data and waterborne disease outbreak history, known sources of human fecal contamination in close proximity to the well, and sensitive hydrogeologic features (
e.g.,
karst). Ninety-six of the 180 potentially vulnerable wells were selected for additional consideration. Selected wells were located in 22 States and 2 US territories. Additional water quality information was then successfully obtained for 94 of the wells through use of a single one liter grab sample which was subsequently tested for several microbial indicators (see Table II-6). The wells from Phase I served as the well selection pool for Phase II sampling.
In Phase II, 23 of the Phase I wells were selected for monthly sampling for one year. Seven additional wells were selected from a list of state-nominated wells for a total of 30 wells, located in 17 States and 2 US territories. The additional seven wells were based on other criteria, including historical water quality data, known contaminant sources in proximity to the well, hydrogeologic character or to replace wells that were no longer available for sampling. Samples were analyzed for enteroviruses,
Legionella,
enterococci,
E. coli, Clostridium perfringens,
total coliforms, somatic coliphage, male-specific coliphage and Bacteroides phage. For each sample analyzed for enteric viruses and bacteriophages, an average of approximately 6,000 liters of water were filtered and analyzed by cell culture.
Twenty samples from seven wells were enterovirus positive and were speciated by serotyping. Coxsackievirus and echovirus, as well as reovirus, were identified. The range in virus concentration in enterovirus-positive samples was 0.9-212 MPN/100 liters (MPN, or most probable number, is an estimate of concentration).
The hydrogeologic settings for the seven enterovirus-positive wells were
karst (3), a gravel aquifer (1), fractured bedrock (2), and a sandy soil and alluvial aquifer (1). The karst wells were all positive more than once. The gravel aquifer was also enterovirus-positive more than once, with 4 of 12 monthly samples positive.
3. Missouri Ozark Aquifer Study #1
The purpose of this study was to determine the water quality in recently constructed community public water system wells in the Ozark Plateau region of Missouri. This largely rural region is characterized by carbonate aquifers, both confined and unconfined, with numerous karst features throughout. A confining layer is defined in this study as a layer of material that is not very permeable to ground water flow and that overlays an aquifer and acts to prevent water movement into the aquifer.
The US Geological Survey, working with the Missouri Department of Natural Resources, selected a total of 109 wells, in both unconfined and confined aquifers (Davis and Witt, 1998, 1999). In order to eliminate poorly constructed wells from the study, most of the selected wells had been constructed within the last 15 years. Wells were also selected to obtain good coverage of the aquifer and to reflect the variability in land use. All wells were sampled twice, in summer and winter. Evidence of fecal contamination was found in a number of wells. Thirteen wells had samples that were PCR-positive for enterovirus.
4. Missouri Ozark Aquifer Study #2
The purpose of this study is to determine the water quality in older (pre-1970) CWS wells in the Ozark Plateau region of Missouri to supplement the Missouri Ozark Aquifer Study #1, by Davis and Witt (1998, 1999). This largely rural region is characterized by carbonate aquifers, both confined and unconfined, with numerous karst features throughout.
The US Geological Survey, working with the Missouri Department of Natural Resources, sampled a total of 106 wells (Femmer, 1999), in both unconfined and confined aquifers. Wells (all of which were constructed before 1970) were selected for monitoring to obtain good coverage of the aquifer, and to reflect the variability in land use. Priority was given to wells that had completion records, well operation and maintenance history and wells currently being used. Each well was sampled once (during the spring). No wells were enterovirus-positive by cell culture.
5. Missouri Alluvial Aquifer Study
The purpose of this study was to determine water quality in wells located in areas that were subjected to recent flooding. The wells are located primarily in the thick, wide alluvium of the Missouri and Mississippi rivers. Sampling (117 samples) occurred during the period of March through June 1996. Twelve wells served as control wells (uncontaminated) and were sited in “deep rock” aquifers or upland areas. A total of 64 wells were sampled.
Many of the wells had been flooded. Fifty-five were affected by a flood in 1995. In addition, some of the wells sampled had been flooded around the surface well casing prior to the sampling event, and several were flooded at the time of sampling (Vaughn, 1996).
6. Wisconsin Migrant Worker Camp Study
The purpose of this study was to determine the quality of drinking water in the 21 public ground water systems serving migrant worker camps in Wisconsin (US EPA, 1998a). These transient, non-community water systems are located in three geographic locations across the State. Each well was sampled monthly for six months, from May through November, 1997. The study conducted sampling for male-specific coliphage, total coliforms and
E. coli.
When detections of coliforms occurred, the specific type of coliform was further identified (speciated). One total coliform positive sample was identified to contain
Klebsiella pneumoniae.
Along with the microbial indicators, nitrate and pesticides were also measured.
Other factors were compared to the microbial and chemical sampling results of the study. Well construction records were available for 14 of the wells. The mean casing depth was 109 feet (range 40 to 282 feet) and the mean total well depth was 155 feet (range 44 to 414 feet). Most of these 14 wells are also reported to terminate in a sand or sandstone formation.
Investigators detected male-specific coliphage in 20 of 21 wells during the six-month sampling period, but never detected
E. coli.
In addition, four wells had nitrate levels that exceeded the EPA MCL for nitrate.
7. EPA Vulnerability Study
The purpose of this study was to conduct a pilot test of a new vulnerability assessment method by determining whether it could predict microbial monitoring results (U.S. EPA 1998b). The vulnerability assessment assigned low or high vulnerability to wells according to their hydrogeologic settings, well construction and age, and distances from contaminant sources. A total of 30 wells in eight States were selected to represent ten hydrogeologic settings. Selection was based on the following criteria: (1) Wells representing a variety of conditions relevant to the vulnerability predictions; (2) wells with nearby sources of potential fecal contamination; and (3) wells with sufficient well and hydrogeologic information available.
Samples were taken and tested for enteroviruses (both by cell culture and PCR), hepatitis A virus (HAV) (by PCR), rotavirus (by PCR), Norwalk virus (by PCR), and several indicators (total coliforms, enterococci, male-specific coliphage, and somatic coliphage). The only positive result was one PCR sample positive for HAV.
8. US-Mexico Border Study
The purpose of this study was to determine water quality in wells sited in alluvium along the Rio Grande River between El Paso, Texas and the New Mexico border (U.S. EPA, in preparation). The 17 wells selected were perceived to be the most vulnerable, based on well depth, chloride concentration and proximity to contamination sources, especially the Rio Grande River.
The wells tested are relatively shallow and all serve less than 10,000 people. One well serves 8,000 people, while seven wells serve fewer than 100 people. Well depths range from 65 feet to 261 feet, but most are about 150 feet deep. This signifies that water was collected from the middle aquifer, a shallow but potable aquifer. Wells shallower than 65 feet contain chloride concentrations prohibitively high for drinking water.
Samples were collected from each well and tested for enteroviruses (by cell culture), somatic coliphage, and male-specific coliphage. None of the sites were positive for any of the viruses tested.
9. Whittier, CA, Coliphage Study
The purpose of this study was to determine the presence of fecal contamination in all wells located within 500 feet down-gradient of a water recharge infiltration basin (Yanko
et al.,
1999). The 23 wells were sampled once per month for six months.
The wells are sited in similar hydrogeologic settings, although they vary in age and depth. The hydrogeologic setting is primarily a thick layer of unconsolidated sand, with lesser amounts of other sized grains. About 30% of the recharge volume to
the wells is reclaimed water. Wells were all constructed between 1919 and 1989 and produce water from depths ranging from 60-888 feet.
The wells were sampled monthly for a six month period. The samples were tested for total coliforms and indicators of fecal contamination, including male specific coliphage, somatic coliphage, and
E. coli
. Coliphage were found in all wells, and repeatedly in 20 of the 23 wells.
10. Oahu, HI Study
The purpose of this study was to establish a water quality monitoring program to assess the microbial quality of deep ground water used to supply Honolulu (Fujioka and Yoneyama, 1997). A total of 71 wells were sampled, 32 of which were sampled for viruses and 39 of which were sampled for bacteria. The wells are located in carbonate or basalt aquifers.
Each of the wells was tested for several pathogens and indicators of fecal contamination. Bacterial samples taken from 39 wells (79 samples) were tested for total coliforms, fecal streptococci,
Clostridium perfringens
, heterotrophic bacteria (by m-HPC), and
Legionella
(by PCR). Sample volumes were 100 mL for
C. perfringens
and heterotrophic bacteria, and both 100 mL and 500 mL for coliforms and fecal streptococci. For FRNA coliphage (male-specific coliphage), one liter samples from 32 wells (35 samples) were tested by membrane adsorption-elution method, while 24 wells (24 samples) were tested by an enrichment technique developed by Yanko. None of the wells were coliphage-positive, and only one sample each was positive for
E. coli
and fecal streptococci.
11. New England Study
The purpose of this study was to: (1) Determine the prevalence of enteric pathogens in New England's public water supply wells; (2) assess the vulnerability of different systems; and (3) evaluate various fecal indicators.
Wells were selected based on the following criteria: (1) Must have constant withdrawal throughout the year; (2) must be near septic systems, (3) should have, if possible, a history of violations of the MCL for total coliforms or elevated nitrate levels; and (4) must not have direct infiltration by surface water (Doherty, 1998).
Wells were nominated, characterized, selected and sampled by regulatory staff of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. The selection process considered wells in different hydrogeologic settings. Of the 124 total wells, 69 (56%) were located in unconfined aquifers, 31 (25%) were located in bedrock aquifers, 10 (8%) were located in confined aquifer hydrogeologic settings, and 14 (11%) were located in unknown aquifer settings. Each well was sampled quarterly for one year. Enterococci were identified in 20 of 124 wells (16%) and in 6 of 31 (19%) bedrock aquifer wells. Two wells were enterovirus-positive using cell culture methods, both in unconsolidated aquifers. One of these two wells is 38 feet deep and the other well is 60 feet deep. Final results from this study are not yet available.
12. California Study
The purpose of this research is two-fold: (1) To assess the vulnerability of ground water to viral contamination through repeated monitoring, and (2) to assess the potential for bacteria and coliphages to serve as indicators of the vulnerability of ground water to viral contamination (Yates 1999).
Eighteen wells were tested monthly for human enteroviruses (by cell culture (direct RT-PCR, Immunomagnetic separation reverse transcriptase (IMS-RT-PCR) and integrated cell culture RT-PCR) and PCR), HAV (by PCR), rotaviruses (by PCR), somatic and male-specific coliphage, and total coliforms and fecal streptococci. The depth of the wells is variable, but is on the order of about 200 feet (the deeper the well, the less likely contamination). There are some intermittent confining layers.
Of the 230 samples tested for enteroviruses, 6 samples from 6 of the 18 wells were cell culture positive for enteroviruses. Final results from this study are not yet available.
13. Three State PWS Study (Wisconsin, Maryland and Minnesota)
The purpose of the three-state study is to characterize the extent of viral contamination in PWS wells by testing wells in differing hydrogeologic regions and considering contamination over time (Battigelli, 1999). Wells were sampled quarterly for one year in Wisconsin (25 wells), Minnesota (25 wells), and will be sampled in Maryland (up to 35 wells).
Three wells in Wisconsin were positive for enteroviruses by cell culture. Final results for this study are not yet available.
Table II-6.—Ground Water Microbial Occurrence Studies/Surveys
Study
Number of PWS wells sampled and location
Sampling frequency/volume
Indicators monitored (number of POS. wells/number of wells total, unless otherwise indicated)
Pathogenic viruses,
Legionella
(number of POS. wells/number of wells total, unless otherwise
indicated)
1. AWWARF Study
448 wells; 35 States
Sampled once (25 wells sampled twice); 539 samples total, not all analyses conducted on all samples. Sampling volumes: 1512L eluated for virus analyses (5 liter equivalent for RT-PCR, 600L for cell culture), Coliphage 15L, Bacteria 200 mL
Male-sp. coliphage, host
Salmonella
WG-49 (42/440); Somatic coliphage, host
E. coli C
(18/444); Coliphage, host
E. coli
C-3000 (48/444); Total coliform (44/445); enterococci (31/355);
C. perfringens
(1/57)
Cell Culture:
Enterovirus (21/442);
PCR:
Rotavirus (62/425), Hepatitis A virus (31/429), Norwalk virus (3/312), Enterovirus (68/427).
2a. EPA/AWWARF Phase I Study
94 wells; 22 States plus PR and USVI
One sample, 1 L
Somatic coliphage 5/94; 1*; Total coliform 31/94; 9*;
E. coli
18/94; 5*; enterococci 17/94; 3*;
C. perfringens
4/94; 0*; *indicates number of wells positive in Phase I which were not positive or not sampled in Phase II
2b. EPA/AWWARF—Phase II Study
30, of which 23 were from Phase I; 17 States plus PR and USVI
Monthly for one year; Average volume filtered: 6,037 L; Microscopic Particulate Analysis (MPA) data available for each well
Somatic coliphage (16/30); Male specific coliphage (6/30);
Bacteroides
bacteriophage (6/30); Somatic
Salmonella
bacteriophage (6/30); Total coliform (24/30); enterococci (21/30);
C. perfringens
(10/30);
E. coli
(15/30);
E. coli
H7:O157 (0/7)
Cell Culture
: Enterovirus (7/30);
PCR
: polio, entero, Hepatitis A, Norwalk, rota (results not available), (300+ samples from 30 wells; several wells cell culture positive multiple times);
Legionella
sp. (14/30),
Legionella pneumophila
(6/30).
3. Missouri Ozark Plateau Study #1 (Davis and Witt, 1999)
109 wells
Two samples/well, 25 wells sampled once for tritium, 200-300 L ground water filtered at the well head
Somatic coliphage (1/109); Male specific coliphage (10/109); Fecal streptococci (1/109); Fecal coliform (2/109);
E. coli
(0/109)
Cell Culture
: Enterovirus (0/109);
PCR
: Enterovirus (13/109).
4. Missouri Ozark Plateau Studies #2 (Femmer, 1999) (pre-1970 wells)
106 wells
One sample, 200-300 L filtered at the well head
Somatic coliphage (3/106); Male specific coliphage (3/106); Fecal streptococci (8/106); Fecal coliform (8/106);
E. coli
(9/106)
Study in progress;
Cell Culture
: Enterovirus (0/106).
5. Missouri Alluvial Study
64 wells
Sampling occurred during a four month period. Some sampling done during flooding
Somatic coliphage (1/81); Male specific coliphage (1/81);
Bacteroides
bacteriophage (1/81); Total coliform (33/81); Fecal coliform (5/81); Fecal streptococci (12/81)
Cell Culture
: Enterovirus (1//81).
6. Wisconsin Migrant Worker Camp Study
21 wells
Monthly: Bacteria—6 mos.; Phage—5 mos.; Bacteria—100 mL; Phage—1L
Male specific coliphage (20/21); Total coliform (14/21);
E. coli
(0/21);
K. pneumoniae
(1/21)
7. EPA Vulnerability Study
30 wells in 8 States
Each well visited once. Two 1L grab samples and 1500-L sample Equiv. vol. 650L for enterovirus, 100 mL for bacteria, 10 mL to 100L for coliphage, PCR?
Male specific coliphage (0/30); Somatic coliphage (2/24; large volume); Total coliform (4/30); enterococci (0/30)
Cell Culture
: enterovirus (0/30);
PCR
: HAV (1/30), Rota (0/30), Norwalk (0/30), enterovirus (0/30).
8. US-Mexico Border Study (TX and NM)
17 wells
3 (300-1000 gallon) samples/well
Male specific coliphage (0/17); Somatic coliphage (0/17)
Cell Culture
: Enterovirus (0/17).
9. Whittier, CA, Coliphage Study
23 wells
Once a month for 6 months; 4L samples
Male specific coliphage (18/23); Somatic coliphage (23/23); Total coliform (4/23);
E. coli
(0/23)
10. Oahu, Hawaii Study
Virus—32 wells Bacteria—39 wells
Each well sampled 1-4 times; total 79 samples, Virus—1-L;
C. perfringens
, HPC—0.1L; Coliforms, fecal strep—0.1L and 0.5L
Male specific coliphage (0/32); Somatic coliphage (0/32); Total Coliform (3/39);
E. coli
(1/39); Fecal Streptococci (1/39);
C. perfringens
(0/39)
Legionella
sp. (PCR; 15/26),
Legionella pneumophila
(PCR; 1/27).
11. New England Study
124 wells; 6 States
Each well sampled four times over one year; Up to 1500-L sample for virus
Study in progress; Male specific coliphage (4/79); Somatic coliphage (1/70); Total coliform (27/124); Aeromonas hydrophila (19/122);
C. perfringens
(6/119);
E. coli
(0/124); enterococci (20/124)
Study in progress;
Cell Culture
: Enterovirus (2/122);
PCR
: Enterovirus (results not available).
12. California Study
18 wells
14 of 18 wells sampled 12 to 22 times (monthly); Average sample volume 1784 L (range 240-3331 L) 1 l grab sample for indicators; (Coliphage analyzed using 10 mL grab samples, 1-L enrichment samples, IMDS filter eluates and filter concentrates)
Study in progress; Male specific coliphage: (hosts
E. coli
FAMP, S.
typhimurium
WG-49) (4/18); Somatic coliphage: host
E. coli
13706 (13/18); Total coliform (7/18); Fecal streptococci (0/18)
Study in progress;
Cell Culture
: enterovirus (6/18);
PCR
: HAV (0/18), Rota (0/18), enterovirus (direct RT-PCR) (6/18), IMS-RT-PCR (10/18), Integrated
Cell Culture
PCR enterovirus (4/18)).
13. Three-State Study (Wisconsin, Maryland, Minnesota)
50 wells (25 from MN, 25 from WI, additional wells from MD)
Each well sampled four times over one year
Study in progress; Somatic coliphage; Male specific coliphage; Total coliform; enterococci;
C. perfringens
;
E. coli
Study in progress;
Cell Culture
: enterovirus (3/25).
D. Health Effects of Waterborne Viral and Bacterial Pathogens
To assess the public health risk associated with a waterborne pathogen, or group of pathogens, both occurrence data and health effects data are needed. The previous section discussed the occurrence in ground water of pathogens and indicators of fecal contamination. This section discusses the health effects associated with waterborne pathogens, first viral agents and then bacterial.
Viral Pathogens
Table II-7 and II-8 list viral and bacterial pathogens that have caused waterborne disease in ground waters. Unlike some bacterial pathogens, viruses cannot reproduce or proliferate outside a host cell. Viruses that infect cells lining the human gut are enteric viruses. With a few exceptions, viruses that can infect human cells typically cannot infect the cells of other animals and vice versa. This contrasts with many bacterial pathogens, which often have a broader host range. Some enteric viral pathogens associated with water may infect cells in addition to those in the gut, thereby causing mild or serious secondary effects such as myocarditis, conjunctivitis, meningitis or hepatitis. There is also increasing evidence that the human body reacts to foreign invasion by viruses in ways that may also be detrimental. For example, one hypothesis for the cause of adult onset diabetes is that the human body, responding to coxsackie B5 virus infection, attacks pancreatic cells in an auto-immune reaction as a result of similarities between certain pancreas cells and the viruses (Solimena and De Camilli, 1995).
When humans are infected by a virus that infects gut cells, the virus becomes capable of reproducing. As a result, humans shed viruses in stool, typically for only a short period (weeks to a few months). Shedding often occurs in the absence of any signs of clinical illness. Regardless of whether the virus causes clinical illness, the viruses being shed may infect other people directly (by person-to-person spread, contact with infected surfaces,
etc.
) and is referred to as secondary spread. Waterborne viral pathogens thus may infect others via a variety of routes.
Table II-7.—Some Illnesses Caused by Fecal Viral Pathogens
Enteric virus
Illness
Poliovirus
Paralysis.
Coxsackievirus A
Meningitis
, fever, respiratory disease.
Coxsackievirus B
Myocarditis
, congenital heart disease, rash, fever,
meningitis
, encephalitis,
pleurodynia
, diabetes melitis,
eye infections
.
Echovirus
Meningitis
, encephalitis,
rash, fever, gastroenteritis.
Norwalk virus and other caliciviruses
Gastroenteritis.
Hepatitis A virus
Hepatitis.
Hepatitis E virus
Hepatitis.
Small round structured viruses (probably caliciviruses)
Gastroenteritis.
Rotavirus
Gastroenteritis.
Enteric Adenovirus
Respiratory disease,
eye infections
, gastroenteritis.
Astrovirus
Gastroenteritis.
(Data from the 1994 Encyclopedia of Microbiology,
Underline
indicates disease causality rather than association)(Lederberg, 1992).
Bacterial Pathogens
Bacterial pathogens may be primary pathogens (those that can cause illness in most individuals) or secondary or opportunistic pathogens (those that primarily cause illness only in sensitive sub-populations). Unlike most primary pathogens, some opportunistic bacterial pathogens can colonize and grow in the biofilm in water system distribution lines. Some waterborne bacterial agents cause disease by rapid growth and dissemination (
e.g., Salmonella
) while others primarily cause disease via toxin production (
e.g.
,
Shigella,
E. coli
O157,
Campylobacter jejuni
).
Campylobacter, E. coli
and
Salmonella
have a host range that includes both animals and humans;
Shigella
is associated with humans and some other primates (Geldreich, 1996). As noted previously, some waterborne bacterial pathogens can survive a long time outside their hosts.
Most of the waterborne bacterial pathogens cause gastrointestinal illness, but some can cause severe illness too. For example,
Legionella
causes Legionnaires Disease, a form of pneumonia that has a fatality rate of about 15%. It can also cause Pontiac Fever, which is much less severe than Legionnaires Disease, but causes illness in almost everyone exposed. A few strains of
E. coli
can cause severe disease, including kidney failure. One strain,
E. coli
O157:H7 has caused several waterborne disease outbreaks since 1990. It is a prime cause of bloody diarrhea in infants, and can cause hemorrhagic colitis (severe abdominal cramping and bloody diarrhea). In a small percentage of cases, hemorrhagic colitis can lead to a life-threatening complication known as hemolytic uremic syndrome (HUS), which involves destruction of red blood cells and acute kidney failure. From 3% to 5% of HUS cases are fatal (CDC, 1999), and most commonly found in young children and the elderly. Some of the opportunistic pathogens can also cause a variety of illnesses including meningitis, septicemia, and pneumonia (Rusin
et al.
, 1997).
Table II-8.—Some Illnesses Caused by Major Waterborne Bacterial Pathogens
Bacterial pathogen
Illnesses
Campylobacter jejuni
Gastroenteritis, meningitis, associated with reactive arthritis and Guillain-Barre paralysis.
Shigella
species
Gastroenteritis, dysentery, hemolytic uremic syndrome, convulsions in young children, associated with Reiters Disease (reactive arthropathy).
Salmonella
species
Gastroenteritis, septicemia, anorexia, arthritis, cholecystitis, meningitis, pericarditis, pneumonia, typhoid fever.
Vibrio cholerae
Cholera (dehydration and kidney failure).
Escherichia coli
(several species)
Gastroenteritis, hemolytic uremic syndrome (kidney failure).
Yersinia entercolitica
Gastroenteritis, acute mesenteric lymphadenitis, joint pain.
Legionella species
Legionnaires Disease, Pontiac Fever
(Data from the 1994 Encyclopedia of Microbiology, Underline indicates disease causality rather than association)(Lederberg, 1992).
E. Risk Estimate
1. Baseline Risk Characterization
This section provides an estimate of the number of people that may be at risk of microbial illness associated with consumption of fecally contaminated drinking water in populations served by ground water systems. EPA has prepared estimates of the numbers of people at risk of viral illness (and possibly death) from three conditions in which fecal contamination may be introduced to ground water systems: fecal contamination in the source water of systems without disinfection; fecal contamination in the source water of systems with inadequate (less than 4-log as discussed later) or failed disinfection; and fecal contamination of the distribution system.
The first condition in which EPA characterizes the baseline risk is for source contaminated ground water systems which do not have disinfection treatment. EPA characterizes the risk to consumers in these systems in five steps: (1) Calculating the population served by undisinfected systems using ground water sources; (2) determining the occurrence of the pathogens of concern in these systems; (3) assessing the exposure to the pathogens of concern; (4) determining the pathogenicity (likelihood of infection) based on dose-response information for each of the pathogens characterized; and (5) calculating the number of illnesses among the population served resulting from consumption of water containing the pathogens.
EPA then estimates additional illnesses resulting from systems with inadequate or failed disinfection treatment and fecally contaminated source water, and systems in which fecal contamination is introduced into the distribution system. These additional illnesses are estimated based on the causes of contamination which lead to waterborne disease outbreaks reported to the CDC in ground water systems from 1991 to 1996. To estimate these additional illnesses, EPA calculated the ratio of the outbreak illnesses in systems with inadequate or failed disinfection treatment to outbreak illnesses in systems without any disinfection, and the ratio of outbreak illnesses in systems with distribution system contamination to outbreak illnesses in systems without any disinfection.
2. Summary of Basic Assumptions
This risk assessment uses a number of assumptions to arrive at an estimate of the number of people at risk of illness or death due to consumption of water from systems with fecal contamination. Some of these assumptions are necessary because data in these areas simply does not exist.
The feasibility of performing a risk analysis on each and every microbial contaminant is diminished when considering the wide range of different microbial contaminants that exist, and that detection methods for all of these contaminants do not exist. Therefore, the risk assessment assumes that the only people exposed to viral contamination are the people served by those wells which test positive for the two viruses used in the risk assessment model, and the exposed population will be exposed to the virus concentration throughout the entire year. The assumption that the population is exposed only to viruses which are accurately described by the model viruses may lead to an underestimation of exposure.
The model viruses which were chosen to act as surrogates for all viruses fall into two categories; those viruses which have low-to-moderate infectivity but relatively severe health effects, and those viruses which have high infectivity but relatively mild health effects. Exposure to viruses that do not fall into these categories may result in an underestimate or overestimate of risk. Risks are not directly quantified for bacterial contaminants because EPA does not have sufficient data to directly model bacterial risk. However, EPA has adjusted its risk estimate for viral illness to approximate for the risk of bacterial illness.
The simplifying assumptions used in this risk assessment, as well as assessing the exposure in only the positive wells, yields an estimated average risk that EPA assumes is a best estimate of the actual risk given available data.
3. Population Served by Untreated Ground Water Systems
EPA estimates there are 44,000 community ground water systems (CWS) serving 88 million people; 19,000 non-transient, non-community ground water systems (NTNCWS) serving five million people; and 93,000 transient non-community ground water systems (TNCWS) serving 15 million people (SDWIS, 1997a). Of these systems, EPA estimates that 68% percent of CWSs are disinfected (CWSS, 1997) (US EPA, 1997c). Larger CWSs are more likely to practice disinfection than are smaller CWSs (
e.g.,
81% of CWSs serving more than 100,000 people are disinfected while 45% of systems serving less than 100 people disinfect. Estimates of treatment for noncommunity water systems are not as detailed. However, based upon information from State drinking water programs, EPA estimates 28% of NTNCWS and 18% of TNCWS disinfect (US EPA, 1996a).
Based upon the number of people served by ground water systems, and the percentage of systems which disinfect, EPA estimates that 18 million people are served untreated ground water from CWSs, four million people are served untreated water from NTNCWSs, and 13 million people are served untreated water from TNCWSs. There is a potential for double or triple counting of the same people within these estimates since a number of people may be served ground water from more than one of the system type categories. For example, a person may consume water from a CWS at home, and a NTNCWS at work or a TNCS while on vacation. EPA has addressed the potential for double counting in the analysis by assuming that individuals do not consume water from each system type every day (see section V).
4. Pathogens Modeled
EPA is concerned about ground water systems which are fecally contaminated since drinking water in these systems may contain pathogenic viruses and/or bacteria. A wide number of viral and bacterial pathogens have been associated with waterborne disease in ground water systems. However, there are inadequate data for EPA to
characterize the risk attributable to each pathogen because detection methods are not available for all pathogens. Additionally, detection methods which are available may be insensitive and incapable of detecting the presence of viruses at very low concentrations. However, even at low concentrations, viruses in drinking water can result in infection. To the extent that detection methods do not exist for a particular pathogen, there may be a resultant underestimation of the risk of illness and death.
In this analysis, EPA estimates the number of illnesses annually associated with two types of pathogenic viruses found in fecally contaminated ground water. These two types of viruses are designated as Type A and Type B viruses for this analysis. Type A viruses represent those viruses which are highly infective, yet have relatively mild symptoms (
e.g.,
gastroenteritis). For this analysis, rotavirus is used as a surrogate for all Type A viruses because rotavirus has been detected in drinking water sources, dose-response data have been prepared for rotavirus and rotavirus has been implicated as the etiologic agent in incidents of waterborne disease. Type B viruses represent those viruses which have low-to-moderate infectivity, yet have potentially more severe symptoms (
e.g.,
myocarditis), and are represented by echovirus. Echovirus also has available dose-response data (Regli
et al,
1991) and has been implicated in a waterborne disease outbreak (Haefliger
et al.,
1998).
The risk assessment used model viruses as surrogates of the actual viruses present. As a result, the risk assessment provides an estimation of risks. The additional risks from other viruses may be higher or lower depending on their occurrence or pathogenicity. For example, if the risk assessment estimated the risks from exposure to Norwalk virus (a Type A virus), using rotavirus as a surrogate, the morbidity rate may be higher for adults than the rate assumed in the model. An outbreak in an Arizona resort in 1989 was believed to be caused by a Norwalk-like virus. This agent may have been responsible for an outbreak which caused illness in 110 out of 240 guests of all ages (Lawson
et al,
1991), a 46% morbidity rate. This is much higher than the morbidity rate of 10% for Type A virus among people older than two. National occurrence data do not exist for many of the other pathogens that may occur in drinking water; therefore, EPA has limited its estimation of risk to only those viral pathogens for which occurrence data and dose response data are available.
Occurrence studies show a significant occurrence of bacterial indicators in ground water wells; for example, almost 9% percent of the wells sampled in the AWWARF study tested positive for the presence of enterococci (Abbaszadegan
et al.,
1999). However, EPA cannot directly estimate national illnesses from bacterial pathogens such as
Salmonella,
due to a lack of occurrence data for those pathogens. EPA believes that the majority of waterborne illnesses due to unknown etiological agents are caused by viruses because viruses move more readily in the ground, remain viable longer and are more infectious than bacteria. Also, more methodologies exist for the identification of bacterial pathogens than for viral pathogens and therefore bacterial pathogens are more likely to be identifiable. The CDC data shows that for every 100 viral or unknown etiological agent illnesses there were 20 bacterial illnesses. Therefore, EPA estimates that the number of viral illnesses can be increased by 20% to account for bacterial illnesses in ground water systems.
5. Microbial Occurrence and Concentrations
EPA reviewed the ground water viral occurrence data (see discussion of occurrence studies in section II. C.) to develop estimates of: the portion of ground water sources which are contaminated with viruses, the period of time in which the wells are contaminated, and the concentration of viruses within the contaminated wells. EPA believes that improperly constructed wells may have significantly higher virus occurrence and concentrations than properly constructed wells (wells which do not comply with State well construction codes). Improperly constructed wells are likely to have more pathways for the introduction of viruses and less natural filtration by the overlying hydrogeologic material. Therefore, the exposure and risks from consumption of water from improperly constructed wells will most likely be higher. As a result, the exposure and risks should be assessed separately for properly and improperly constructed wells in order to develop a range reflecting national conditions.
EPA determined that the study conducted by AWWARF represents conditions in properly constructed wells and the EPA/AWWARF (Lieberman
et al.,
1994, 1999) study represents conditions in improperly constructed wells. EPA selected the AWWARF study as representative of properly constructed wells (
e.g.,
wells with casing and grout to confining layers, sanitary seals,
etc.
) because it excluded wells of improper construction and the wells sampled were representative of hydrogeologic conditions for water supply wells in the United States. However, the wells selected may not have been representative of the probability of fecal contamination in ground water wells nationally. As noted in section II.C.1., one-third of the wells in this study were originally selected for the purpose of evaluating the effectiveness of the PCR method based on criteria that may over represent high risk wells. The remaining two-thirds were selected to balance the sample with wells that were representative of hydrogeologic conditions for drinking water wells nationally. EPA requests comment and data which would help assess the representativeness of the wells in the AWWARF study sample. However, EPA believes that the AWWARF study data represents the best currently available data on occurrence of viral pathogens in properly constructed wells and has thus used it as the basis of baseline incidence estimates.
EPA selected the EPA/AWWARF study to be representative of wells of improper construction because it sampled wells which were determined to be vulnerable to contamination. The EPA/AWWARF study considered wells as vulnerable based on one or more of the following considerations: hydrogeology, well construction, State nominations, microbial sampling results, close proximity to known sources of fecal contamination, and water quality history. For the purposes of the risk assessment, all wells determined to be vulnerable were used as surrogates for improperly constructed wells. The results from this study may over estimate the risks from improperly-constructed wells generally, since it included only wells that were deliberately selected through a several step process to be highly vulnerable to contamination (see section II.C.2.). EPA estimated that 83% of systems have properly constructed wells based upon data from ASDWA's Survey of Best Management Practices for Community Ground Water Systems (ASDWA, 1998).
The AWWARF study data include viral cell culture assay results which detect the presence of viable enterovirus (including echovirus and other Type B viruses) in the samples. Twenty-one of the 442 wells sampled (4.8%) tested positive for the Type B viral cell culture. EPA determined that this data can be used to estimate the percentage of properly constructed wells which are contaminated at a given point in time with Type B viruses. The AWWARF
study data also include rotavirus PCR results which indicate that 62 of the 425 (14.6%) wells sampled contained rotavirus genetic material. EPA determined that the PCR results may be an overestimation of the portion of wells with viable Type A viruses since PCR methods do not distinguish between viable and non-viable viruses. To calculate the portion of PCR positive wells which contain viable viruses EPA compared the enterovirus (Type B) cell culture results to the enterovirus (Type B) PCR analysis and found that for every enterovirus cell culture positive well, there were 3.3 PCR enterovirus positive wells. EPA estimated that the 1/3.3 rotavirus PCR wells contained viable virus, and therefore 4.4% (14.6%/3.3) of all properly constructed wells were contaminated with Type B viruses at any one time. Viral and bacterial indicator data indicate there are a greater percentage of wells in the study which were fecally contaminated than contained the viral pathogens at the time of sampling. For example, almost 16% of all wells tested positive for viral cell culture, male specific coliphage or enterococci.
The EPA/AWWARF study sampled wells vulnerable to contamination monthly for a one year period and found that 6.0% of the samples tested positive for enterovirus (Type B) cell culture. Since cell culture methods are not available for rotavirus (the representative of Type A viruses), the EPA/AWWARF study tested samples using PCR methods for the presence of rotavirus to estimate the occurrence of Type A viruses in improperly constructed wells. However, the PCR data is still under review by researchers and unavailable for consideration in this analysis. EPA therefore based the estimate of occurrence of viable Type A viruses in improperly constructed wells on the ratio of viable Type A virus in the AWWARF study (4.4%) to Type B viruses in the AWWARF study (4.7%). Applying this ratio (4.4%/4.7%) to the percentage of improperly constructed wells containing Type B viruses (6.0%), EPA estimates the percentage of improperly constructed wells with Type A virus contamination is 5.5%.
EPA estimated Type A and Type B virus concentrations are 0.36 viruses/100L for properly constructed wells based on the mean enterovirus concentration in the AWWARF study. EPA also estimated Type A and Type B virus concentrations to be 29 viruses/100L for improperly constructed wells based on the mean enterovirus concentration in EPA/AWWARF study. Although these studies determined the concentrations of enteroviruses (Type B viruses) only, for the purposes of this analysis EPA assumed the concentrations of Type A viruses and Type B viruses were equivalent.
6. Exposure to Potentially Contaminated Ground Water
EPA developed estimates of the population potentially exposed to viral pathogens based upon the estimates of population served by undisinfected systems and the portions of those systems which are estimated to be virally contaminated. In CWS, 18 million people are served undisinfected ground water. Assuming 17% of wells serving these people are improperly constructed (and 83% are properly constructed) from the results of the ASDWA BMP Survey (ASDWA, 1997), and Type A viruses occur in 4.4% of properly constructed wells and 5.5% of improperly constructed wells, the population potentially exposed to Type A viruses in CWS is 842,000. Similar calculations can be conducted to obtain the population exposed to Type A viruses in NTNCWS, as well as Type B viruses in all ground water systems. EPA's estimates of the population potentially exposed to the viruses are presented in Table II-9. Many of the people exposed to the Type A viruses are also exposed to the Type B viruses, therefore these number cannot be added.
Table II-9.—Population Potentially Exposed to Virally Contaminated Drinking Water in Undisinfected Ground Water Systems
System type
Population potentially exposed to type A virus
Population potentially exposed to type B virus
CWS
842,000
918,000
NTNCWS
175,000
191,000
TNCWS
567,000
619,000
To estimate the risk of illness from consumption of undisinfected ground water, EPA estimated people consume an average 1.2 liters of water per day based upon the 1994-1996 USDA Continuing Survey of Food Intakes by Individuals (US EPA, 2000a). EPA accounted for the variability in consumption by modeling consumption as a custom distribution fit to age groups in the survey data. EPA also assumed that people consume water from CWSs 350 days per year; from NTNCWSs 250 days per year; and from TNCWSs 15 days per year. EPA notes that these assumptions may allow for some double counting of exposure, but EPA is not aware of data to allow a more refined breakdown of consumption. EPA requests comment on these assumptions.
7. Pathogenicity
After estimating the population potentially exposed to untreated (i.e., not disinfected) contaminated ground water and the amount of water consumed, the next step is to assess the pathogenicity of the viruses. Once viruses are consumed, the likelihood of infection and illness varies depending on the virus.
For this analysis, the likelihood of infection from ingestion of one or more Type A or Type B viruses are estimated based on dose response equations developed for rotavirus (Ward
et al.,
1986) and echovirus (Schiff
et al.
, 1984), respectively. These equations estimate the annual probability of infection following consumption of a specified virus and are based on studies of healthy volunteers. The volunteers for these studies are typically between the ages of 20 and 50, and therefore, may underestimate the probability of infection in sensitive subpopulations (
e.g.
, children and elderly) and the immunocompromised (
e.g.
, nursing home residents and AIDS patients). Rotavirus dose-response information was used to represent Type A viruses, while echovirus dose-response information was used to represent Type B viruses.
Once a person becomes infected, the likelihood of illness (morbidity) varies, depending on the pathogen and the sensitivity of the consumer. For Type A viruses, EPA assumed the percent of people becoming ill once infected is 88% for children under the age of two (Kapikian and Chanock, 1996). EPA assumed a morbidity rate of 10% for all other populations based upon a study of a rotavirus outbreak (Foster
et al.
, 1980) and incidents of rotavirus in families with infants ill with rotavirus (Wenman
et al.
, 1979).
EPA assumed the percent of people infected with Type B viruses who become ill also varies with age: 50% for children five years of age and less, 57% for individuals between 5 and 16 years of age, and 33% for people older than 16. EPA estimated these age-specific morbidity values based on data from a community-wide echovirus type 30 epidemic (Hall
et al.
, 1970) and from the New York Viral Watch (Kogon
et al.
, 1969).
Secondary illnesses result from individuals being exposed to individuals who contracted the illness from drinking water. For this analysis, EPA estimates the additional number of
people who become ill as a result of secondary spread. For Type A viruses, EPA assumed that an additional 0.55 people will become ill from every child that becomes ill through consumption of drinking water. This assumption is based on a study of children under five years old, ill with rotavirus, who spread the illness to others in their households (Kapikian and Chanock, 1996). For Type B viruses EPA assumed that 0.35 additional people will become ill through secondary spread. This assumption was based on a review of various epidemiological studies for echovirus (Morens
et al.
, 1991). There is some uncertainty as to the exact rate of secondary spread for Type B viruses, so EPA has assumed that the secondary spread rates range from 0.11 to 0.55.
The probability that an ill person will die as a result of an illness is referred to as mortality. EPA expects Type A viruses to result in far fewer deaths than Type B viruses. EPA assumed a mortality rate for all age groups of 0.00073 percent. This assumption was based on an estimate of 20 rotavirus deaths per year out of 2,730,000 cases of rotavirus diarrhea in children 0-4 years old (Tucker
et al.
, 1998). EPA assumed the mortality rate for Type B viruses be 0.92 percent for infants one month or less. This assumption was based upon studies of hospitalized infants (Kaplan and Klein, 1983). For the rest of the population, EPA assumed that 0.04 percent of people ill from Type B viruses will die. These estimates may underestimate the number of infant deaths due to Type B viral illnesses, since Jenista et al. (1984) and Modlin (1986) reported a three percent case fatality rate for infants (one month or less) which is three times the value used in the model.
8. Potential Illnesses
EPA estimates, based upon the assumptions described earlier, that 98,000 viral illnesses each year are caused by consuming drinking water in undisinfected public ground water systems. EPA further estimates that nine of these people die each year.
EPA believes there are additional waterborne illnesses and deaths among consumers of drinking water from public ground water systems beyond those estimated due to contaminated source waters in undisinfected systems. Between 1991 and 1996 there were 1,260 waterborne outbreak illnesses reported to CDC which were attributed to microbial contamination of the source and inadequate or interrupted disinfection, and 944 waterborne illnesses reported to CDC which were attributed to distribution system contamination in ground water systems. In that same period there were 2,924 reported outbreak illnesses in source contaminated undisinfected system. This results in 0.43 (1,260/2,924) additional illnesses in source contaminated, ground water systems with failed disinfection for every illness from undisinfected, fecally contaminated ground water. Based on similar analysis, there are also 0.32 (944/2,924) additional illnesses due to distribution system contamination for every one illness due to source contamination in undisinfected ground water systems. (This ratio does not apply to transient noncommunity water systems, because they do not have distribution systems.) EPA assumed the ratios of the causes of reported outbreak illnesses is equal to the ratio of the causes of all waterborne illnesses. Therefore, EPA estimates, based upon these ratios, that an average of 42,000 additional illnesses and four additional deaths occur each year as a result of source contamination and inadequate or interrupted disinfection. EPA also estimates that an average of 28,000 additional illnesses and three additional deaths are caused each year by distribution system contamination. Table II-10 presents the estimates of viral illness and death under current conditions.
Table II-10.—Estimates of Baseline Viral Illness and Death Due to Contamination of Public Ground Water Systems
Cause of contamination
No. of type A virus illnesses
No. of type A virus deaths
No. of type B virus illnesses
No. of type B virus deaths
total illnesses types A & B
Total deaths types A & B
Source contamination/undisinfected system
78,000
1
20,000
8
98,000
9
Source contamination/disinfected system
34,000
8,000
4
42,000
4
Distribution system contamination
22,000
6,000
3
28,000
3
All Causes
134,000
1
34,000
14
168,000
16
Because of a lack of occurrence data for bacterial pathogens in ground water, risks from bacterial contamination of ground water sources and distribution systems are not quantified in this assessment. Although it is believed that viruses are more readily transported through the subsurface than bacteria (Sinton
et al.
, 1997), ground water system disease outbreaks caused by bacterial pathogens such as
Shigella, Salmonella
spp., and
Campylobacter
spp. and
E. coli
O157:H7 have been reported. For the period 1971-1996, 56 outbreaks, resulting in more than 10,000 illnesses and 11 deaths, were attributed to bacterial pathogen contamination of public ground water systems. More than 20% of these bacterial outbreaks occurred since 1991, and several outbreaks were attributed to gross fecal contamination of distribution lines.
As previously stated, there may be an additional 20% of illnesses caused by bacterial pathogens (in the absence of viral pathogens) in fecally contaminated ground water. Therefore, the numbers of illnesses and deaths presented in Table II-10 may underestimate the true numbers of annual illnesses and deaths by 20% (an estimated 34,000 additional illnesses and three additional deaths).
9. Summary of Key Observations
In conclusion, EPA believes that at any one point in time (most approximately 90 percent) ground water systems provide uncontaminated water. However, the risk characterization described herein indicates that a subset of ground water systems represent a potential risk to public health, which clearly supports the need to proceed with regulation of these systems. According to the assessment, EPA estimates that approximately 168,000 people are at risk to viral illness and 16 people are at risk of death, annually. It is noted that this analysis focuses primarily on the potential of gastrointestinal illness caused by exposure to viruses, therefore; the potential for additional illnesses from ground water contaminated only by pathogenic bacteria also exists and may account for an additional 34,000 illnesses and three deaths annually.
Therefore, the estimate of illnesses represents a potential underestimate of the actual illnesses attributed to consumption of water from ground water systems. Based on this analysis EPA believes that risk of microbial illness exists for a substantial number of people served by ground water systems. Consequently, EPA believes that the proposed regulatory provisions discussed later provide a meaningful opportunity for public health risk reduction.
10. Request for Comments
EPA seeks comment on the data, criteria and methodology used in the risk assessment, and where any different approaches may be appropriate. EPA also seeks comment on the assumptions used in this assessment, as well as the conclusions reached, and any additional data that commenters may be able to provide on occurrence, exposure, infectivity, morbidity, or mortality associated with microbial pathogens in ground water.
F. Conclusion
In EPA's judgment, the data and information presented in previous sections relating to outbreaks, occurrence, adverse microbial health effects, exposure, and risk characterization demonstrate that there are contaminants of concerns that exist in ground water at levels and at frequencies of public health concern. Moreover, as discussed in detail later, the Agency believes there are targeted risk-based regulatory strategies that provide a meaningful opportunity to reduce public health risk for a substantial number of people served by ground water sources.
EPA recognizes that there are particular challenges associated with developing an effective regulatory approach for ground water systems. These include first, the large number of ground water systems; second, the fact that only a subset of these systems appear to have microbial contamination (although a larger number are likely to be vulnerable); and third, that most ground water systems range from being small to very small in terms of population served. These factors combine to underscore the fact that a one-size-fits-all approach cannot work. This point was made repeatedly by participants in public stakeholder meetings across the country, and EPA agrees. The task therefore is to develop a protective public health approach which ensures a baseline of protection for all consumers of ground water and sets in place an increasingly targeted strategy to identify high risk or high priority systems that require greater scrutiny or further action.
III. Discussion of Proposed GWR Requirements
The information outlined earlier indicates that the primary causes of waterborne related illnesses are associated with source water contamination and untreated ground water, source water contamination and unreliable treatment, water system deficiencies, and a subset of waterborne disease outbreaks of unknown causes. The requirements and options proposed today address each of these areas through a multiple-barrier approach which relies upon five major components: periodic sanitary surveys of ground water systems requiring the evaluation of eight elements and the identification of significant deficiencies; hydrogeologic assessments to identify wells sensitive to fecal contamination; source water monitoring for systems drawing from sensitive wells without treatment or with other indications of risk; a requirement for correction of significant deficiencies and fecal contamination through the following actions: eliminate the source of contamination, correct the significant deficiency, provide an alternative source water, or provide a treatment which achieves at least 99.99 percent (4-log) inactivation or removal of viruses, and compliance monitoring to insure disinfection treatment is reliably operated where it is used.
A. Sanitary Surveys
1. Overview and Purpose
A key element of the multiple-barrier approach is periodic inspection of ground water systems through sanitary surveys. According to the Total Coliform Rule (TCR), a sanitary survey is an onsite review of the water source, facilities, equipment, operation and maintenance of a public water system for the purpose of evaluating the adequacy of such source, facilities, equipment, operation and maintenance for producing and distributing safe drinking water (40 CFR 141.2). The Agency believes that periodic sanitary surveys, along with appropriate corrective actions, are indispensable for assuring the long-term quality and safety of drinking water. When properly conducted, sanitary surveys can provide important information on a water system's design and operations and can identify minor and significant deficiencies for correction before they become major problems. By taking steps to correct deficiencies exposed by a sanitary survey, the system provides an additional barrier to microbial contamination of drinking water.
The Agency proposes the following sanitary survey requirements: (1) States, or authorized agents, conduct sanitary surveys for all ground water systems at least once every three years for CWSs and at least once every five years for NCWSs; (2) sanitary surveys address all eight elements set out in the EPA/State Joint Guidance on sanitary surveys (outlined later in this section); (3) States provide systems with written notification which describes and identifies all significant deficiencies no later than 30 days of the on-site survey; and (4) systems consult with the State and take corrective action for any significant deficiencies no later than 90 days of receiving written notification of such deficiencies, or submit a schedule and plan to the State for correcting these deficiencies within the same 90 day period; and (5) States must confirm that the deficiencies have been addressed within 30 days after the scheduled correction of the deficiencies.
A ground water system that has been identified as having significant deficiencies must do one or more of the following: eliminate the source of contamination, correct the significant deficiency, provide an alternate source water, or provide a treatment which reliably achieves at least 99.99 percent (4-log) inactivation or removal of viruses before or at the first customer. Ground water systems which provide 4-log inactivation or removal of viruses will be required to conduct compliance monitoring to demonstrate treatment effectiveness. The ground water system must consult with the State to determine which of the approaches, or combination of approaches, are appropriate for meeting the treatment technique requirement. Ground water systems unable to address the significant deficiencies in 90 days, must develop a specific plan and schedule for meeting this treatment technique requirement, submit them to the State, and receive State approval before the end of the same 90-day period. For the purposes of this paragraph, a “significant deficiency” includes, : a defect in design, operation, or maintenance, or a failure or malfunction of the sources, treatment, storage, or distribution system that the State determines to be causing, or has the potential for causing the introduction of contamination into the water delivered to consumers.
Sanitary surveys provide a comprehensive and accurate record of the components of water systems, assess the operating conditions and adequacy of the water system, and determine if
past recommendations have been implemented effectively. The purpose of the survey is to evaluate and document the capabilities of the water system's sources, treatment, storage, distribution network, operation and maintenance, and overall management in order to ensure the provision of safe drinking water. In addition, sanitary surveys provide an opportunity for State drinking water officials or approved third party inspectors to visit the water system and educate operators about proper monitoring and sampling procedures, provide technical assistance, and inform them of any changes in regulations.
Sanitary surveys have historically been conducted by State drinking water programs as a preventative tool to identify water system deficiencies that could pose a threat to public health. In 1976, EPA regulations established, as a condition of primacy, that States develop a systematic program for conducting sanitary surveys, with priority given to public water systems not in compliance with drinking water regulations (40 CFR 142.10 (b)(2)). This primacy requirement did not define the scope of sanitary surveys or specify minimum criteria.
In 1989, the TCR included a provision that requires systems that serve 4,100 people or less and collecting fewer than five routine total coliform samples per month to conduct a periodic sanitary survey every five years, with an exception made for NCWS that use protected and disinfected ground water to conduct the survey every ten years. The TCR, however, does not establish what must be addressed in a sanitary survey or how such a survey should be conducted. The responsibility is on the system rather than the State for completing the sanitary survey (40 CFR 141.21(d)(2)). The TCR requires systems to use either a State official or an agent approved by the State to conduct the sanitary survey.
The IESWTR (63 FR 69478, December 16, 1998), established requirements for primacy States to conduct sanitary surveys for all systems using surface water or ground water under the direct influence of surface water. The rule also requires States to have the appropriate authority for ensuring that systems address significant deficiencies. The State must perform a survey at least once every three years for CWSs and every five years for NCWSs. These surveys must encompass the eight major areas defined by the EPA/State Joint Guidance (discussed in section 3).
This GWR proposal and the IESWTR differ in the requirements for a system to correct any significant deficiency. In the IESWTR, States are specifically required to have the appropriate rules or other authority to requi
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