DRINKING WATER

EPA Has Improved Its 

Unregulated 

Contaminant 

Monitoring Program, 

but Additional Action 

Is Needed

Report to Congressional Requesters

January 2014

GAO-14-103

United States Government Accountability Office
United States Government Accountability Office

Highlights of GAO-14-103, a report to 

congressional requesters

January 2014

DRINKING WATER

EPA Has Improved Its Unregulated Contaminant 

Monitoring Program, but Additional Action Is Needed

Why GAO Did This Study

EPA’s UCMR program collects data on 

unregulated contaminants in the 

nation’s drinking water. EPA uses 

these data and other information to 

make regulatory determinations—

decisions on whether to regulate 

additional drinking water contaminants. 

It is currently in its third data collection

cycle, UCMR3. 

GAO was asked to examine the UCMR

program. This report examines: (1) the 

extent to which EPA implemented 

GAO’s prior recommendations to 

improve the program and 

opportunities, if any, to strengthen it 

further; (2) the factors EPA considered 

when it selected the UCMR3 

contaminants and the limitations, if 

any, it faced in selecting them; and (3) 

the extent to which UCMR data 

support regulatory determinations. 

GAO reviewed EPA documents, 

surveyed 48 subject matter experts, 

assessed the UCMR program against 

statutory requirements and other 

standards, and interviewed EPA 

officials. 

What GAO Recommends

Congress should consider amending 

the Safe Drinking Water Act to allow 

EPA to monitor for more than 30

contaminants under certain 

circumstances, and to adjust statutory 

time frames so UCMR data can inform 

regulatory determinations in the same 

cycle. GAO, among other things, 

recommends that EPA vary the 

monitoring frequency based on 

contaminant type. In commenting on a 

draft of this report, EPA generally 

agreed with GAO’s findings, 

conclusions, and recommendations. 

What GAO Found

The Environmental Protection Agency (EPA) has implemented all of the 

recommendations GAO made in its May 2011 report to improve the Unregulated 

Contaminant Monitoring Rule (UCMR) program. In that report, GAO

recommended that EPA (1) monitor for the full 30 contaminants allowed by 

statute, (2) monitor for most or all contaminants using a more robust monitoring 

approach, and (3) select sufficiently sensitive minimum reporting levels (MRL) for 

monitoring contaminants. EPA now requires public water systems to monitor for

30 contaminants in the UCMR3 program, using its most robust monitoring 

approach for a majority of these contaminants, and setting MRLs as low as can 

be reliably measured, according to EPA. The Safe Drinking Water Act (SDWA) 

requires EPA to vary the monitoring frequency based on the type of contaminant

likely to be found, but EPA used a standard monitoring frequency for all 

contaminants. This may result in inaccurate estimates of the occurrence of 

sporadically occurring microbes (e.g., viruses) or pesticides, according to experts 

GAO surveyed and studies it reviewed. In such cases, the monitoring data may 

not provide reliable estimates of contaminant occurrence. 

EPA used 10 factors to select the 30 contaminants for UCMR3, but its selection 

process faced some limitations. Officials told GAO that the contaminants did not 

have to meet all 10 of the selection factors to be chosen, but 3 were very 

important (1) the availability of an analytical method to detect contaminants, (2) 

the reliability of health effects information on the contaminants, and (3) the need 

for data to support regulatory determinations for priority contaminants. However, 

EPA is limited by a statutory cap of 30 contaminants every 5 years, which 

restricts its ability to collect data on additional contaminants that could have been 

monitored for little additional cost. SDWA’s legislative history reflected concerns

with the ability of public water systems to absorb such costs, but many of the 

analytical methods EPA is using for UCMR3 are able to test a single sample of 

drinking water for more than one contaminant at a time. However, because of the 

limit of 30, EPA cannot always take advantage of this efficiency and is unable to 

gain economies of scale using monitoring that is already under way. 

EPA uses UCMR data to support regulatory determinations but faces a time lag 

when doing so. EPA has used UCMR data to support 10 out of 12 regulatory 

determinations it has made since 2008 and is currently using UCMR data to 

inform the determinations expected in 2015. However, a time lag between the 

statutory deadline for making regulatory determinations and when UCMR data 

are available delays determinations on given contaminants until the following 

cycle. The 2-year time frame SDWA originally established from the time EPA 

publishes the UCMR list to when it makes regulatory determinations has not 

provided enough time for the agency to incorporate the UCMR data into the 

determinations. The UCMR3 monitoring, data collection, and analysis overlap 

with the time when EPA will be making its regulatory determinations for 

contaminants from its most recent Contaminant Candidate List. Consequently, 

UCMR data are not available to support regulatory determinations for 

contaminants during the cycle in which they are monitored; rather, UCMR data 

typically are not used until the next cycle. EPA officials told GAO that most of the 

UCMR3 data, which are being collected from 2013 to 2015, will be used to 

support the regulatory determinations it expects to issue in 2020 instead of 2015. 

View GAO-14-103. For more information, 

contact J. Alfredo Gómez (202) 512-3841 or 

gomezj@gao.gov.
Page i GAO-14-103 Drinking Water

Letter 1 

Background 4

EPA Has Improved the UCMR Program by Implementing Our 

Recommendations, but Its Monitoring Frequency May Yield 

Some Inaccurate Estimates 11

EPA Considered 10 Factors to Select Contaminants for 

Monitoring, but Its Selection Process Faced Limitations 21

UCMR Data Support Regulatory Determinations, but Time Lag 

Results in Delays and Reliance on Older Data 35

Conclusions 44

Matters for Congressional Consideration 46

Recommendations for Executive Action 47

Agency Comments 47

Appendix I Objectives, Scope, and Methodology 49

Appendix II UCMR3 Contaminants 53

Appendix III Information on Analytical Methods 54

Appendix IV Round 2 Survey Questionnaire and Results 58

Appendix V List of Experts Who Completed the Surveys 79

Appendix VI Comments from the Environmental Protection Agency 80

Appendix VII GAO Contact and Staff Acknowledgments 83

Related GAO Products 84

Contents
Page ii GAO-14-103 Drinking Water

Tables

Table 1: Public Water Systems Required to Participate in the Third 

Unregulated Contaminant Monitoring Rule 7

Table 2: EPA Programs to Address Unregulated Contaminants in 

Drinking Water 9

Table 3: Number of Public Water Systems Required to Participate 

in the First, Second, and Third Unregulated Contaminant 

Monitoring Rules (UCMR1, UCMR2, and UCMR3) 13

Table 4: Monitoring Frequency by System Size and Water Supply 

Source for the Third Unregulated Contaminant Monitoring 

Rule 16

Table 5: Contaminants of Emerging Concern Detectable with an 

Analytical Method Already in Use 30

Figures

Figure 1: EPA Selection Factors for Identifying Contaminants for 

Monitoring under the Third Unregulated Contaminant 

Monitoring Rule (UCMR3) 22

Figure 2: Contaminant Selection and Rule Development Process 

for the Third Unregulated Contaminant Monitoring Rule 24

Figure 3: UCMR3 Timeline 26

Figure 4: UCMR Data Do Not Inform Regulatory Determinations in 

the Same Cycle 38

Figure 5: About 10 Years Typically Pass before Regulatory 

Determinations Are Made for Contaminants on the CCL 42

Figure 6: EPA’s Process for Analytical Method Development 56
Page iii GAO-14-103 Drinking Water

Abbreviations

CCL Contaminant Candidate List

EPA Environmental Protection Agency

GC-MS gas chromatograph-mass spectrometer

MRL minimum reporting level

MTBE methyl tertiary-butyl ether

NAWQA National Water-Quality Assessment Program

OMB Office of Management and Budget

PFC perfluorinated chemical

SDWA Safe Drinking Water Act

UCMR Unregulated Contaminant Monitoring Rule

USGS United States Geological Survey

VOC volatile organic compound

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Page 1 GAO-14-103 Drinking Water

441 G St. N.W.

Washington, DC 20548

January 9, 2014

The Honorable Henry A. Waxman

Ranking Member

Committee on Energy and Commerce

House of Representatives

The Honorable Edward J. Markey

United States Senate

Most Americans receive their drinking water from the more than 160,000 

public water systems in the United States, all of which are subject to key 

requirements of the Safe Drinking Water Act (SDWA).1 Under SDWA, the 

Environmental Protection Agency (EPA) is authorized to regulate 

contaminants in public water systems.2 Currently, EPA regulates more 

than 89 drinking water contaminants. In 1996, in the midst of concerns 

about the number and pace of regulations required under the act and the 

need to better focus limited resources on contaminants of greatest public 

health concern, Congress enacted significant amendments to SDWA. The 

1996 amendments to SDWA also directed EPA, among other things, to 

identify unregulated contaminants that present the greatest public health 

concern, establish a program to monitor drinking water for unregulated 

contaminants, and decide whether or not to regulate at least 5 such 

contaminants every 5 years.3 EPA decisions about whether or not to 

regulate these contaminants are called regulatory determinations. Since 

1996, EPA has made 21 regulatory determinations and has decided to 

regulate one of the contaminants, perchlorate.4 EPA has identified 116 

unregulated contaminants, including perchlorate and others such as 

 

1

Pub. L. No. 93-523 (1974), codified as amended at 42 U.S.C. §§300f-300j-26 (2013).

2

Under SDWA, a drinking water contaminant is defined as any physical, chemical, 

biological, or radiological substance or matter in water. 

3

In the 1996 amendments, Congress removed a previous requirement that EPA regulate 

25 new contaminants every 3 years. 

4

EPA decided to regulate perchlorate in 2011 and is currently developing a regulatory 

proposal for it. Perchlorate is both a naturally occurring and man-made chemical that is

used to produce rocket fuel, fireworks, flares and explosives. It can also be present in 

bleach and in some fertilizers. According to EPA, perchlorate may have adverse health 

effects because scientific research indicates that this contaminant can disrupt the thyroid’s 

ability to produce hormones needed for normal growth and development.
 

Page 2 GAO-14-103 Drinking Water

formaldehyde and Salmonella enterica, that it believes may occur in 

public water systems and may also require regulation. Those unregulated 

contaminants are listed on EPA’s current Contaminant Candidate List 

(CCL).5

In addition, EPA has established the Unregulated Contaminant Monitoring 

Rule (UCMR) program, to monitor drinking water for unregulated 

contaminants, under the 1996 amendments to SDWA. As part of the 

UCMR, the SDWA amendments require EPA to issue a list every 5 years 

identifying up to 30 contaminants to be monitored by public water 

systems. The UCMR program is currently in its third 5-year cycle, known 

as UCMR3. EPA estimates that UCMR3 will cost $87 million from 2012 to 

2016, of which $21 million will be paid by EPA. EPA will pay for small 

water systems’ costs for the UCMR; the remaining $66 million will be paid 

by large water systems.6 The UCMR, CCL, and regulatory determinations 

are related to each other. First, the CCL identifies unregulated 

contaminants that may require regulation in the future. Through the 

UCMR program, public water systems monitor for some of the CCL 

contaminants to determine how often and at what level the contaminants 

occur in drinking water. EPA then makes regulatory determinations about 

contaminants on the CCL using UCMR data, information about the 

contaminants’ health effects, and other information for support.

In May 2011, we reported that EPA’s monitoring program under the 

UCMR did not use EPA’s full statutory authority under SDWA, use 

sufficiently sensitive testing methods, or employ sufficiently robust 

monitoring approaches.7 First, EPA did not use its full allotment of 30 

contaminants as authorized by SDWA in either of the first two UCMR 

cycles (UCMR1 and UCMR2), which limited the agency’s progress in 

obtaining data on drinking water contaminants. Second, in some cases, 

EPA required public water systems to use testing methods (i.e., analytical 

methods) that were not sufficiently sensitive to identify the presence of 

 

5

The current Contaminant Candidate List is referred to as CCL3. 

6

For purposes of the UCMR, EPA defines a small water system as one serving 10,000 or 

fewer people. EPA defines a large water system as one that serves more than 10,000 

people.

7

GAO, Safe Drinking Water Act: EPA Should Improve Implementation of Requirements on 

Whether to Regulate Additional Contaminants, GAO-11-254 (Washington, D.C.: May 27, 

2011).
 

Page 3 GAO-14-103 Drinking Water

contaminants at EPA’s health reference level—the health benchmark 

EPA uses in assessing whether to regulate specific contaminants. Third, 

EPA used a limited sample size of 300 public water systems for UCMR1 

for one of the program’s monitoring approaches, which resulted in 

occurrence data that, according to EPA documents, were not sufficient to 

make national estimates of contaminant occurrence. In the 2011 report, 

we also recommended that EPA use its full statutory authority to monitor 

for 30 unregulated contaminants, select minimum reporting levels that are 

sufficiently sensitive to detect the presence of contaminants in public 

water systems at levels of public health concern, and monitor for most or 

all contaminants using the program’s most robust monitoring approach.

In this context, you asked us to examine the UCMR program. Specifically, 

our objectives for this report were to: (1) evaluate the extent to which EPA 

has implemented the recommendations we made in 2011 to improve the 

UCMR program and identify any opportunities to strengthen it further; (2) 

identify the factors that EPA considered when it selected the 

contaminants for monitoring under UCMR3 and the limitations, if any, that 

EPA faced in selecting the contaminants; and (3) examine the extent to 

which UCMR data support regulatory determinations.

To identify the steps EPA has taken in response to the recommendations 

we made in 2011, we reviewed EPA documents, including EPA’s 

proposed and final rules for the UCMR program, assessed the UCMR 

sample design against statutory requirements and statistical standards, 

and interviewed EPA officials. To identify the factors EPA considers when 

selecting contaminants, we reviewed EPA documents, including EPA’s 

proposed and final rules for the UCMR program and SDWA requirements, 

and interviewed EPA officials. To determine how EPA uses the UCMR 

data to support its regulatory determinations, we reviewed EPA and 

Federal Register documents and interviewed EPA officials. In addition, to 

obtain further information about the UCMR program and identify 

opportunities to strengthen it further, we conducted a two-round Delphi 

survey8 of experts selected for their knowledge of one or more of the 

following areas: drinking water, contaminant monitoring, analytical 

methods, toxicology, risk assessment, and environmental regulation. In 

the first round of the survey, we selected 14 experts who demonstrated 

 

8

The Delphi method consists of surveying experts in two or more rounds to obtain group 

agreement or consensus on key topics.
 

Page 4 GAO-14-103 Drinking Water

familiarity with EPA’s CCL, UCMR, and regulatory determination 

processes. We asked them 10 open-ended questions about how various 

aspects of the UCMR program helped or hindered EPA in (1) selecting 

priority contaminants, (2) monitoring for selected contaminants, and (3) 

using the data to support regulatory determinations. We analyzed the 

responses provided by the experts and developed closed-ended 

questions for the second round of the survey. To identify experts for the 

second round of the survey, we developed a preliminary list of experts, 

which included the 14 experts who completed the first round of the survey 

and others identified through interviews with stakeholders and our review 

of public comments provided on EPA’s proposed rules. We contracted 

with the National Academy of Sciences to identify additional experts. We 

selected 48 experts for the second round of the survey based on their 

knowledge of one or more of the following topic areas: drinking water, 

contaminant monitoring, analytical methods, toxicology, risk assessment, 

and environmental regulation. For the first round of the survey, we 

received responses from 14 of the 14 experts we surveyed and, for the 

second round, we received responses from 40 of 48 experts we surveyed 

(83 percent response rate). The information that we obtained from the 

expert surveys is not generalizable to all experts that have an interest in 

or knowledge of drinking water contaminant monitoring but does provide 

several experts’ views on the UCMR program. For more information on 

our objectives, scope, and methodology see appendix I. See appendix IV 

for a copy of the survey questions and responses for the second round of 

the survey and appendix V for a list of the experts who completed the 

surveys.

We conducted this performance audit from June 2012 to January 2014 in 

accordance with generally accepted government auditing standards. 

Those standards require that we plan and perform the audit to obtain 

sufficient, appropriate evidence to provide a reasonable basis for our 

findings and conclusions based on our audit objectives. We believe that 

the evidence obtained provides a reasonable basis for our findings and 

conclusions based on our audit objectives.

This section presents information on (1) regulated and unregulated 

contaminants in drinking water, (2) the UCMR program and SDWA 

requirements, and (3) laboratories and methods used to analyze drinking 

water.

Background
 

Page 5 GAO-14-103 Drinking Water

Drinking water contaminants include chemical and microbial substances, 

some of which can harm human health. For example, prolonged exposure 

to arsenic in drinking water can cause skin damage or circulatory 

problems and, over time, may increase cancer risks. Contaminants may 

be naturally occurring or introduced through other means. EPA has 

identified three ways that drinking water generally becomes 

contaminated. First, contaminants can find their way into drinking water 

sources from industrial waste releases, agricultural runoff, and other 

pollution sources. Second, contamination can occur during the treatment 

of water by forming what are known as “disinfection by-products.”

9 Third, 

contaminants can “leach” or dissolve out of the materials used for 

treatment, storage, and distribution of water.

EPA regulates drinking water contaminants under SDWA by issuing 

legally enforceable standards, known as National Primary Drinking Water 

Regulations or “primary standards” that generally limit the levels of these 

contaminants in public water systems. EPA has issued primary standards 

addressing more than 89 contaminants. States generally enforce these 

standards through compliance monitoring. Under compliance monitoring, 

public water systems collect a sample of drinking water, analyze the 

sample for specific contaminants, and report the results to states. To 

analyze the samples, water systems and states use analytical methods 

developed by government agencies, universities, and other organizations. 

EPA evaluates analytical methods for drinking water and approves those 

it determines meet agency requirements for monitoring contaminants.

Laboratories analyzing drinking water compliance samples must be 

certified by the state or EPA. EPA establishes schedules for how often 

water systems must monitor for regulated contaminants. The monitoring 

frequency generally depends on the contaminant, previous monitoring 

results, the type of source water, and the size of the population served by 

the water system.

Unregulated drinking water contaminants include chemical and microbial 

substances and are not currently subject to primary standards under 

 

9

To protect drinking water from disease-causing organisms, or pathogens, water suppliers 

may add a disinfectant, such as chlorine, to drinking water. However, disinfectants can 

react with naturally occurring materials in the water to form by-products, some of which 

may pose health risks.

Regulated and 

Unregulated Contaminants 

in Drinking Water
 

Page 6 GAO-14-103 Drinking Water

SDWA.10 Exposure to unregulated drinking water contaminants may pose 

a human health risk, particularly to vulnerable subpopulations such as 

pregnant women, infants, the elderly, and those with compromised 

immune systems.11 Unregulated contaminants include industrial 

chemicals, military chemicals, pesticides, bacteria, and other microbes 

and chemicals. They also include contaminants of emerging concern— 

contaminants characterized by a perceived, potential or real threat to 

human health or the environment or by a lack of published health 

standards. Examples include pharmaceuticals, such as prescription and 

over-the-counter drugs, and ingredients in personal care products, such 

as cosmetics and soaps. A contaminant may also be considered to be 

emerging because a new source of public exposure has been discovered 

or a new detection method or treatment technology has been developed.

Under the UCMR program, EPA collects data about the occurrence of 

unregulated contaminants in drinking water. The UCMR program collects 

data on the extent of the occurrence of unregulated contaminants in all 

public water systems serving more than 10,000 people and in a nationally 

representative sample of smaller systems. These data inform EPA’s 

decisions about whether to issue primary standards for unregulated 

contaminants. Under the UCMR, EPA is to identify up to 30 unregulated 

contaminants that may be present in drinking water and establishes a 

monitoring program to obtain data on the extent of their occurrence. 

These data help EPA determine whether drinking water contamination is 

occurring and estimate its level and frequency. EPA established a threetiered approach for monitoring UCMR contaminants that includes (1) 

assessment monitoring, (2) screening survey, and (3) pre-screen testing. 

EPA’s approach is based primarily on the availability of analytical 

methods to monitor the contaminants. Assessment monitoring is used to 

monitor contaminants that can be detected by well-established analytical 

methods that are widely used in drinking water laboratories. The 

screening survey is used to monitor contaminants that can be detected by 

more recently developed analytical methods that are used in fewer 

 

10States may regulate some of these contaminants. Under state laws, some state 

environmental agencies have the authority to regulate additional contaminants or establish 

more stringent standards than federal regulations, while others do not have these 

authorities. 

11GAO-11-254. 

UCMR Program and 

SDWA Requirements
 

Page 7 GAO-14-103 Drinking Water

drinking water laboratories. Pre-screen testing is used to monitor 

contaminants that can be detected by very new or specialized analytical 

methods that are used in a small set of drinking water laboratories.

Approximately 6,000 public water systems are currently participating in 

the UCMR program. Participating public water systems are monitoring for 

contaminants under one or more of the three tiers. EPA varies the 

number of public water systems required to monitor under each tier. 

UCMR monitoring is conducted by all large community and nontransient, 

noncommunity public water systems serving more than 10,000 people.12

Monitoring is also conducted by a nationally representative sample of 

other public water systems that EPA selects (see table 1). In addition, a 

sample of community and nontransient, noncommunity water systems, 

and transient water systems are required to allow EPA to conduct prescreen testing under UCMR3.13

Table 1: Public Water Systems Required to Participate in the Third Unregulated Contaminant Monitoring Rule

Monitoring approach Type of system Size of system Number of systems 

Assessment monitoring 

using well-established 

analytical methods 

Community water systems and 

nontransient, noncommunity water 

systems

Systems serving more than 

10,000 people

All (~4,200)

Systems serving 10,000 or 

fewer people

Representative sample of 

800 systems 

Screening survey using 

more recently developed 

analytical methods

Community water systems and 

nontransient, noncommunity water 

systems

Systems serving more than 

100,000 people

All (~400)

Systems serving 10,001 to 

100,000 people

Representative sample of 

320 systems

Systems serving 10,000 or 

fewer people

Representative sample of 

480 systems

 

12EPA defines a community water system as a public water system that has at least 15 

service connections used by year-round residents or regularly serves an average of at 

least 25 year-round residents. EPA defines a nontransient, noncommunity water system 

as a public water system that is not a community water system and regularly serves at 

least 25 of the same people over 6 months per year. There are more than 52,000 

community water systems and more than 19,000 nontransient, noncommunity water 

systems.

13EPA defines a transient noncommunity water system as a public water system that does 

not regularly serve at least 25 of the same people over 6 months per year. There are more 

than 87,000 transient, noncommunity water systems.
 

Page 8 GAO-14-103 Drinking Water

Monitoring approach Type of system Size of system Number of systems 

Pre-screen testing using 

specialized analytical 

methods 

Nondisinfecting groundwater systems 

including community water systems, 

nontransient, noncommunity water 

systems, and transient, noncommunity 

water systems 

Systems serving 1,000 or 

fewer people 

Representative sample of 

800 systems

Source: GAO analysis of EPA documents.

The UCMR program is part of a larger framework established by SDWA 

that also includes the CCL and requires EPA to make regulatory 

determinations for at least five of the contaminants on that list every 5 

years. The CCL is a list of unregulated contaminants that are known or 

anticipated to occur in public water systems and that may require 

regulation. SDWA directs EPA to select contaminants that pose the 

greatest public health concern for consideration for the CCL and 

regulatory determinations.

14 A regulatory determination is a formal 

decision on whether EPA should initiate a rulemaking process to develop 

a primary standard for a specific drinking water contaminant. The UCMR, 

CCL, and regulatory determinations framework is implemented by three 

different branches within EPA’s Office of Ground Water and Drinking 

Water’s Standards and Risk Management Division: the Technical Support 

Center administers the UCMR program; the Targeting and Analysis 

Branch develops the CCL; and the Standards and Risk Reduction Branch 

leads the development of the regulatory determinations.

SDWA requires EPA to make regulatory determinations for at least five of 

the contaminants on the CCL every 5 years. Regulatory determinations 

can be positive (i.e., a primary standard is needed) or negative (i.e., no 

primary standard is needed). Under SDWA, EPA is to make a positive 

regulatory determination and subsequently issue a primary standard 

when (1) the contaminant may have an adverse effect on the health of 

persons; (2) the contaminant is known to occur or there is a substantial 

likelihood that the contaminant will occur in public water systems with a 

frequency and at levels of public health concern; and (3) in the sole 

judgment of the Administrator, regulation of such contaminant presents a 

meaningful opportunity for health risk reduction for persons served by 

public water systems. EPA can make a negative regulatory determination 

when the SDWA conditions are not met. SDWA set recurring 5-year 

deadlines for the CCL, UCMR, and regulatory determinations. The initial 

 

1442 U.S.C. § 300g-1(b)(1)(C) (2013). 
 

Page 9 GAO-14-103 Drinking Water

deadlines were staggered such that EPA was required to publish the CCL 

in the Federal Register first (February 1998), the UCMR list 18 months 

later (August 1999), and the regulatory determinations 2 years after that 

(August 2001). The cycle restarts with the next CCL, UCMR, and 

regulatory determinations due 5 years after the first set of deadlines. 

However, EPA has not always met the SDWA deadlines. Moreover, EPA 

has not issued the CCL, UCMR, and regulatory determinations separated 

by the 18-month and 2-year time frames that were originally established 

by statute.15 The cycle is currently in its third iteration. EPA refers to the 

programs in the current cycle as CCL3, UCMR3, and the CCL3 regulatory 

determinations (see table 2).

Table 2: EPA Programs to Address Unregulated Contaminants in Drinking Water

Program

Contaminant Candidate

List (CCL)

Unregulated Contaminant

Monitoring Rule (UCMR) Regulatory determinations

Purpose Identify unregulated contaminants 

that are known or anticipated to 

occur in public water systems 

Monitor unregulated contaminants to 

determine the extent of their 

occurrence in drinking water

Decide whether or not to regulate 

contaminants on the CCL using

UCMR data, health effects

information, and other information

SDWA 

requirement

Publish list every 5 years Publish a list of up to 30 

contaminants for monitoring, every 5 

years

Decide whether or not to regulate at 

least 5 CCL contaminants, every 5 

years

Outputs 1998 (60 contaminants on CCL1)

2005 (51 contaminants on CCL2)

2009 (116 contaminants on CCL3)

1999 (26 contaminants on UCMR1)

2007 (25 contaminants on UCMR2)

2012 (30 contaminants on UCMR3)

2003 (9 negative determinations for 

CCL1)

2008 (11 negative determinations for 

CCL2)

2011 (1 positive determination–out 

of cycle)

2015 (determinations for CCL3 

expected)

Source: GAO analysis of EPA information.

The UCMR program’s primary purpose is to inform regulatory 

determinations, but EPA can also use the UCMR data to develop health 

advisories for some of the contaminants it decides not to regulate. Health 

advisories provide information on contaminants that can harm human 

health and are known or anticipated to occur in drinking water. They 

provide technical guidance on health effects to assist EPA regional 

 

15Under the time frames set out in the statute, EPA would have issued CCL3 in 2008, the 

list of UCMR3 contaminants in 2009, and the regulatory determinations for CCL3 in 2011. 
 

Page 10 GAO-14-103 Drinking Water

offices, states, and other public health officials. EPA has issued new or 

updated health advisories for nine contaminants it decided not to 

regulate.16 The advisories identify concentrations of contaminants at 

which adverse health effects are not anticipated to occur over specific 

exposure durations (1 day, 10 days, several years, and a lifetime). 

Drinking water health advisories are not legally enforceable standards 

and, according to EPA, are subject to change as new information 

becomes available.

Private analytical laboratories and some water utilities’ laboratories 

conduct the analytical testing for the UCMR contaminants. All laboratories 

conducting analyses for UCMR3 must be approved by EPA. In general, 

laboratories must first successfully complete the registration and 

application process, which includes testing for contaminants using EPAspecified analytical methods, before receiving EPA’s approval.17

Approved laboratories must adhere to the quality assurance and quality 

control procedures and criteria outlined in the methods and rule language 

to maintain their approval status and may be subject to on-site laboratory 

or paper audits. Laboratories also post occurrence data and required 

quality control data electronically in EPA’s data system, the Safe Drinking 

Water Accession and Review System, within 120 days of the sample 

collection date.18

EPA specifies the analytical methods that laboratories participating in the 

UCMR program use to detect contaminants. Some methods can detect a 

single contaminant while others can detect a group of similar 

contaminants. Because the UCMR collects nationwide data, agency 

 

16EPA has issued or updated health advisories for the following 9 contaminants: (1) 

1,1,2,2-tetrachloroethane; (2) 2,4-dinitrotoluene; (3) 2,6-dinitrotoluene; (4) boron; (5) 

tetrachloroterephthalic acid; (6) monomethyl tetrachloroterephthalic acid; (7) manganese; 

(8) sodium; and (9) sulfate. EPA also developed consumer information for Acanthamoeba. 

17Laboratories conducting the pre-screen testing analyses for viruses and pathogen 

indicators are under direct contracts with EPA and are subject to an analogous laboratory 

approval process. 

18These data are included in EPA’s National Contaminant Occurrence Database. EPA 

developed the database to satisfy the statutory requirements set by Congress in the 1996 

amendments to SDWA to maintain a national drinking water contaminant occurrence 

database using sampling data for both regulated and unregulated contaminants in public 

water systems.

Laboratories and Methods 

Used to Analyze Drinking 

Water
 

Page 11 GAO-14-103 Drinking Water

officials told us EPA’s goal is to use analytical methods that yield 

consistently high-quality monitoring data from public water systems 

across the country. EPA officials told us that the agency develops or uses 

analytical methods for the UCMR program that enable it to meet this goal.

In particular, agency officials told us these methods must (1) have 

sufficient “holding times”;19 (2) be able to be used successfully by a 

variety of labs with varying levels of expertise; and (3) be used effectively 

in different types of drinking water. EPA officials said it typically takes 1 or 

2 years to develop a standard analytical method that meets these 

requirements and up to 3 years or longer to develop more complex 

methods. See appendix III for more information on analytical methods.

EPA has implemented the three recommendations we made in our May 

2011 report to improve the UCMR program.20 The technical changes EPA 

has made to UCMR3 are significant improvements over prior UCMR 

cycles and have increased the program’s productivity and statistical 

strength, among other things. However, the program’s monitoring 

frequency may result in inaccurate estimates of the occurrence of some 

contaminants.

 

19Holding time is the time between the collection of a water sample by a public water 

system and the laboratory analysis of that water sample. 

20Three of the 17 recommendations we made in GAO-11-254 applied to the UCMR 

program. Other recommendations concern regulatory determinations and could affect the 

UCMR program due to the relationship between the programs.

EPA Has Improved 

the UCMR Program 

by Implementing Our 

Recommendations, 

but Its Monitoring 

Frequency May Yield 

Some Inaccurate 

Estimates
 

Page 12 GAO-14-103 Drinking Water

In UCMR3, EPA implemented our recommendations to (1) monitor for 30 

contaminants; (2) monitor for most or all contaminants using the 

program’s more robust monitoring approach; and (3) select minimum 

reporting levels (MRL) that are sufficiently sensitive to detect the 

presence of contaminants in public water systems at levels of public 

health concern as follows:21

Monitor for 30 contaminants. In our May 2011 report,22 we reported that 

EPA did not use its full statutory authority to monitor for 30 contaminants 

in implementing the first two cycles of the UCMR program. Specifically, 

EPA required that 26 and 25 contaminants be monitored under UCMR1 

and UCMR2, respectively. As a result, EPA did not obtain occurrence 

data for 9 additional contaminants, which in turn, limited the agency’s 

productivity in obtaining critical information to support its regulatory 

determinations. In its response to our recommendation that it use its full 

statutory authority, EPA stated it supports a goal of including as many 

priority contaminants as possible in each 5-year monitoring cycle. 

Accordingly, in May 2012, EPA published its final rule for UCMR3 

requiring public water systems to monitor for 30 contaminants (see app. II 

for a list of the 30 contaminants).23

Use more robust monitoring approach. In 2011, we reported that EPA 

officials described the assessment monitoring approach as “the gold 

standard” for obtaining sufficient data on national occurrence of drinking 

water contaminants to support regulatory determinations, but that it had 

used the more limited screening survey approach for a majority of the 

contaminants monitored under UCMR1 and UCMR2, as shown in table 3. 

The screening survey monitoring approach produces estimates of 

national occurrence with greater uncertainty than those provided by 

 

21MRLs represent an estimate of the lowest concentration of a compound that can be 

quantitatively measured by members of a group of experienced drinking water 

laboratories. Under the UCMR, laboratories are to report all analyses of listed

contaminants. Laboratories report values when they are equal to or greater than the 

established MRL, or report that the analysis was below the MRL. 

22GAO-11-254. 

23One of the 30 contaminants to be monitored under UCMR3 is total chromium, a 

regulated contaminant. EPA included total chromium in UCMR3 to collect data on it 

concurrent with data for chromium-6, an associated unregulated contaminant. EPA used a 

different statutory authority, section 1445(a)(1)(A) of SDWA, to require monitoring for total 

chromium. 

EPA Has Implemented All 

of GAO’s 2011 

Recommendations to 

Improve the UCMR 

Program
 

Page 13 GAO-14-103 Drinking Water

assessment monitoring because it requires a smaller sample of public 

water systems to monitor. For example, under UCMR1, the screening 

survey required a sample of 300 public water systems to monitor. In 

contrast, approximately 3,800 systems were required to conduct 

assessment monitoring. In EPA’s response to our recommendation that it 

conduct monitoring for most or all contaminants using the assessment 

monitoring approach, EPA stated that it supports a goal of using 

assessment monitoring for as many contaminants as is practical to obtain 

more robust occurrence data for and also to achieve higher confidence in 

the national estimates. EPA is requiring assessment monitoring for a 

majority of the contaminants under UCMR3. In addition, for UCMR2 and 

UCMR3, EPA expanded the sample size of the screening survey to 

increase the statistical strength of the monitoring results. We analyzed 

EPA’s methodology for selecting the sample of systems for the screening 

survey under UCMR2 and UCMR3 against standard statistical criteria, 

and we determined that the larger sample size should allow EPA to make 

national estimates of contaminant occurrence with smaller margins of 

error and higher levels of confidence compared with the first UCMR. In 

addition, 26 of the 40 experts who participated in our survey thought the 

screening survey monitoring approach for UCMR3 is likely to provide EPA 

with sufficient data to determine whether contaminants occur with a 

frequency and at levels of public health concern. Further, EPA officials 

told us that the UCMR2 screening survey occurrence data are sufficient 

for supporting regulatory determinations, whereas, in its 2008 regulatory 

determinations notice, EPA stated that the occurrence data were 

insufficient to support regulatory determinations for 12 of the 14 

contaminants monitored under the UCMR1 screening survey.

Table 3: Number of Public Water Systems Required to Participate in the First, Second, and Third Unregulated Contaminant 

Monitoring Rules (UCMR1, UCMR2, and UCMR3)

Monitoring approach UCMR1 UCMR2 UCMR3 

Number of contaminants to be monitored

Assessment monitoring 12 10 21a

Screening survey 14 15 7 

Pre-screen testing 0 0 2 

Total number of contaminants 26 25 30

Number of public water systems required to participate

Assessment monitoring ~3,800b ~4,200b ~5,000b

Screening survey 300c ~1,200c ~1,200c

Pre-screen testing NA NA 800

Source: GAO analysis of EPA information.
 

Page 14 GAO-14-103 Drinking Water

a

UCMR3 assessment monitoring includes total chromium, a regulated contaminant being monitored 

under another authority.

b

Assessment monitoring includes all public water systems serving over 10,000 people and a 

representative sample of 800 systems serving 10,000 or fewer people.

c

EPA increased the sample size of the screening survey for UCMR2 and UCMR3. Specifically, under 

UCMR1, the screening survey included a sample of 300 systems (120 systems serving over 10,000 

people and 180 systems serving 10,000 or fewer people). In contrast, under UCMR2 and UCMR3, 

the screening survey includes all systems serving over 100,000 people; a representative sample of 

320 systems serving 10,001 to 100,000 people; and a representative sample of 480 systems serving 

10,000 or fewer people.

Select sufficiently sensitive MRLs. In 2011, we reported that the utility of 

the UCMR occurrence data was reduced because EPA had not used 

sufficiently sensitive MRLs to detect the presence of contaminants at 

levels of public health concern. Specifically, for 9 of the 20 contaminants 

for which EPA made regulatory determinations in 2003 and 2008, the 

MRL exceeded EPA’s health reference level—the health benchmark EPA 

uses to assess whether the detection of a specific contaminant may 

indicate a potential human health risk.24 As a result, occurrence of these 9 

contaminants at a level higher than the health reference level, but lower 

than the MRL, may not have been detected. In its response to our 

recommendation that EPA use MRLs that are sufficiently sensitive, EPA 

stated it supports a goal of establishing minimum reporting levels that are 

sufficiently sensitive to reliably detect the known and likely occurrence of 

contaminants in public water systems at levels of public health concern 

and provide useful and credible information on the occurrence of the 

contaminants in public drinking water systems.25 EPA has since revised 

its approach for selecting MRLs for monitoring selected contaminants in 

an effort to increase the likelihood that the monitoring will be sufficiently 

sensitive to detect the presence of contaminants at levels of public health 

concern. Specifically, EPA officials told us that, for UCMR3, the agency 

set the MRLs based on how low the method could reliably measure 

 

24The 9 contaminants include 4 monitored under, or in association with UCMR1, and 5 

monitored under the program that preceded the UCMR. Under the earlier program, public 

water systems were required to monitor for up to 48 unregulated contaminants and to 

report monitoring results to the states or to EPA.

25GAO-11-254. 
 

Page 15 GAO-14-103 Drinking Water

specific contaminants.26 These levels are based on method sensitivity 

(i.e., not adjusted upward based on available health effects information). 

In some cases, the MRLs for UCMR3 are set well below EPA’s current 

health reference levels, according to EPA’s final rule for UCMR3. 

However, health effects research on some UCMR3 contaminants is still in 

progress, and the health reference levels are subject to change. EPA 

believes that its new approach will be more effective than its past 

approach because, by monitoring for contaminants at the lowest 

concentrations feasible, UCMR3 is more likely to detect contamination at 

levels of public health concern, even if new health effects data result in 

lower health reference levels in the future, as anticipated by its final rule 

for UCMR3.

EPA has taken steps to improve the UCMR program, but the program’s 

standard monitoring frequency may result in inaccurate estimates of the 

occurrence of certain contaminants. In particular, several experts we 

surveyed and studies on contaminant occurrence indicated that the 

UCMR3 standard monitoring frequency may result in inaccurate 

estimates of the occurrence of sporadically occurring microbes (e.g., 

viruses) and seasonally applied pesticides. SDWA calls for EPA to vary 

the monitoring frequency and schedule for public water systems based on 

three criteria (1) the number of persons served by the system, (2) the 

source of the system’s water supply, and (3) the contaminants likely to be 

found. Under UCMR3, EPA varies the monitoring frequency for systems 

based on a system’s size and water supply (e.g., surface water or 

groundwater), but it does not vary it based on the type of contaminant 

likely to be found. Specifically, under UCMR3, surface water systems and 

 

26 EPA set most of the MRLs for the UCMR3 contaminants at the level of micrograms per 

liter (μg/L), generally ranging from 0.0001 μg/L to 1 μg/L. Some contaminants are able to 

be detected at much lower concentrations than others, due to their chemical properties, 

among other factors. The levels set for the UCMR3 contaminants are generally more 

sensitive than the levels set for UCMR1 and UCMR2 contaminants, which generally 

ranged from 0.5 μg/L to 10 μg/L and from 0.002 μg/L to 2 μg/L, respectively.

UCMR Monitoring 

Frequency May Yield 

Inaccurate Estimates of 

Some Contaminant 

Occurrence
 

Page 16 GAO-14-103 Drinking Water

groundwater systems under the direct influence of surface water27 are 

required to conduct quarterly monitoring of selected chemical 

contaminants, while groundwater systems are required to monitor 

selected chemical contaminants twice a year. In addition, nondisinfecting 

groundwater systems that serve 1,000 or fewer people and are located in 

sensitive hydrogeological areas are required to allow EPA monitoring for 

two microbial contaminants (viruses) twice a year (see table 4). The virus 

monitoring in UCMR3 was designed in consideration of where these 

viruses may be more likely to be found—small groundwater systems that 

do not disinfect. Nonetheless, EPA used the standard monitoring 

frequency for viruses; it did not vary the frequency or schedule based on 

the contaminants likely to be found. Similarly, contaminant monitoring 

under UCMR2 occurred quarterly for surface water systems and twice a 

year for groundwater systems for all contaminants. EPA did not vary the 

monitoring frequency or schedule during the seasons when pesticides 

were applied and the likelihood of occurrence was highest.

Table 4: Monitoring Frequency by System Size and Water Supply Source for the Third Unregulated Contaminant Monitoring 

Rule 

System size Water supply source Monitoring frequency 

Assessment monitoring

All systems serving more than 10,000 

people and a representative sample of 800 

systems serving 10,000 or fewer people

Surface water or groundwater under the 

direct influence of surface water 

Quarterly during a 1-year period with 

sampling events 3 months apart 

Groundwater Twice in a 1-year period with sampling 

events 5-7 months apart

Screening survey

All systems serving more than 100,000 

people, a representative sample of 320 

systems serving 10,001 to 100,000 people, 

and a representative sample of 480 systems 

serving 10,000 or fewer people 

Surface water or groundwater under the 

direct influence of surface water 

Quarterly during a 1-year period with 

sampling events 3 months apart

Groundwater Twice in a 1-year period with sampling 

events 5-7 months apart

 

27Groundwater under the direct influence of surface water means any water beneath the 

surface of the ground with significant occurrence of insects or other macroorganisms, 

algae, or large-diameter pathogens such as Giardia lamblia or Cryptosporidium, or 

significant and relatively rapid shifts in water characteristics such as turbidity, temperature, 

conductivity, or pH that closely correlate to climatological or surface water conditions. For 

example, a groundwater source located close enough to nearby surface water, such as a 

river or lake, to receive direct surface water recharge is considered at risk of 

contamination from pathogens that are not normally found in true groundwaters. 
 

Page 17 GAO-14-103 Drinking Water

System size Water supply source Monitoring frequency 

Pre-screen testing

A representative sample of 800 

nondisinfecting groundwater systems 

serving 1,000 or fewer people 

Groundwater Twice in a 1-year period with sampling 

events 5-7 months apart

Source: GAO analysis of EPA documents.

When EPA first established the UCMR program, it explained that the 

standard monitoring frequency for public water systems using surface 

water and groundwater under the direct influence of surface water will 

capture variability in contaminant occurrence because one of each public 

water system’s quarterly sampling events must occur during what EPA 

considers to be the most vulnerable period for drinking water 

contamination, i.e., the period of peak contamination.28 According to 

EPA’s explanation in the Federal Register accompanying the final rule for 

UCMR1, studies show that the greatest risk of contaminant occurrence

for much of the country is the late-spring/early-summer runoff period from 

May to July, particularly for contaminants such as pesticides and nitrate.

29

EPA designed the UCMR3 program to include sampling during this 

period, as designated by EPA or the state. Quarterly monitoring for 

systems using surface water or groundwater under the direct influence of 

surface water occurs during one of three possible time frames (1) 

January, April, July, and October; (2) February, May, August, and 

November; or (3) March, June, September, and December. EPA assigns 

one of these three time frames to each participating public water system 

using surface water or groundwater under the direct influence of surface

water.30 EPA did not specify a vulnerable period for public water systems 

using groundwater in UCMR2 and UCMR3, but it stated that samples will 

 

28Environmental Protection Agency, “Revisions to the Unregulated Contaminant 

Monitoring Regulation for Public Water Systems,” 64 Fed. Reg. 50,556, 50,570, 50,588 

(Sept. 17, 1999).

29Id. at 50,571 ("For much of the United States, east of the Rocky Mountains, many 

studies have shown that the season of greatest vulnerability for contaminant occurrence is 

the late-spring, early-summer runoff-recharge period, particularly for contaminants such as 

pesticides and nitrate (e.g., Larson et al., 1997; Barbash and Resek, 1996; Hallberg, 

1989a,b). For deeper, more confined ground water systems, defining vulnerable periods is 

much more difficult.”). 

30Systems that are unable to monitor within the assigned time frame must contact EPA to 

reschedule their monitoring.
 

Page 18 GAO-14-103 Drinking Water

be taken during all months and seasons of the year when all groundwater 

systems are considered together, according to agency documents.31

However, several experts we surveyed and studies on contaminant 

occurrence indicated that the UCMR standard monitoring frequency may 

not accurately characterize the presence of certain contaminants in public 

water systems. In particular, the monitoring frequency may result in 

inaccurate estimates of the occurrence of sporadically occurring microbes 

(e.g., viruses) and pesticides whose peak concentrations typically occur 

during and after the application season, primarily from April through July. 

For example, EPA’s monitoring frequency may underestimate occurrence 

for compounds such as seasonally applied pesticides, according to one 

expert we surveyed.

As noted above, the UCMR3 standard monitoring frequency may result in 

inaccurate estimates of the occurrence of some microbes and pesticides.

• Microbes. Under UCMR3, EPA selected a representative sample of 

800 nondisinfecting groundwater systems located in sensitive 

hydrogeological areas32 to monitor for two viruses—enterovirus and 

norovirus—using the pre-screen testing monitoring approach.33 In the 

notice for its proposed rule for UCMR3, EPA states that the agency 

limited its selection to those systems serving 1,000 or fewer persons 

because these smaller systems are the least likely to disinfect the 

water and, therefore, the most vulnerable to contamination with 

viruses. Monitoring and analyses are organized and paid for by EPA 

through direct contracts with laboratories. Under UCMR3, each of the 

selected systems will be monitored for the viruses twice during a 12-

month period from January 2013 to December 2015. The systems’ 

 

31Environmental Protection Agency, UCMR2 Categorized Public Comments (Washington, 

D.C.: June 2006); and Environmental Protection Agency, Response to Comments 

Document for the Unregulated Contaminant Monitoring Regulations (UCMR3)

(Washington, D.C.: January 2012). 

32The 800 systems use groundwater wells that do not treat the water and are located in 

areas of vulnerable geology, such as karst aquifers. 

33According to an EPA fact sheet, the primary means of virus-related disease 

transmission is exposure to fecally contaminated water or consumption of food exposed to 

the contaminated water. Exposure to enterovirus-contaminated drinking water can cause 

fever, respiratory illness, rash, conjunctivitis, hand-foot-mouth disease, and meningitis, 

among other things. Exposure to norovirus-contaminated drinking water can cause mild 

fever, vomiting, diarrhea, and cramps. 
 

Page 19 GAO-14-103 Drinking Water

sampling events will be 5 to 7 months apart. However, more than half 

of the experts who completed our survey (23 of 40) said the twiceyearly monitoring requirement for viruses is not likely to provide EPA 

sufficient data to determine whether the contaminants occur with a 

frequency and at levels of public health concern. In addition, 15 

experts who completed our survey stated that more frequent 

monitoring may be warranted to capture the occurrence of viruses in 

public water systems, which many characterized as variable. 

Similarly, a technical presentation that EPA used to support its 

rationale for including the viruses in UCMR3 shows that virus 

occurrence in groundwater systems is highly variable and that 

groundwater recharge events, like heavy precipitation, increase virus 

contamination levels.34 The technical presentation concludes that 

more frequent sampling is necessary to characterize virus occurrence 

in public water systems. Moreover, in the past, EPA varied the 

monitoring frequency for a microbe that public comments on EPA’s 

proposed rule for UCMR1 characterized as sporadically occurring.35

Specifically, under UCMR1, surface water systems and groundwater 

systems monitoring for the microbial contaminant, Aeromonas, were 

required to take samples quarterly, with additional samples taken, so 

that samples generally were collected each month during the warmest 

months of the year (July, August, and September) because EPA 

officials told us that this is when they expected to find contaminant 

occurrence.36 Systems monitored during one of three possible time 

frames (1) January, April, July, August, September, and October; (2) 

February, May, July, August, September, and November; or (3) 

March, June, July, August, September, and December. In contrast, 

UCMR3 does not require any additional monitoring for viruses. As a 

result, the data obtained under UCMR3 may not provide reliable 

estimates of the occurrence of viruses in drinking water.

 

34Wisconsin Water and Health Trial for Enteric Risks (WAHTER Study)—Part 1: Risk of 

Illness from Municipal Groundwater Consumption. EPA Office of Water Symposium on

Groundwater-Borne Infectious Disease, Etiologic Agents and Indicators (Washington, 

D.C.: December 2–4, 2008).

35Environmental Protection Agency, Public Comment and Response Summary for the 

Unregulated Contaminant Monitoring Regulation (Washington, D.C.: August 1999). 

36According to EPA’s website, Aeromonas is a genus of bacteria with the potential to 

contaminate drinking water by evading treatment (e.g., chlorine disinfection) and to cause 

human disease such as gastroenteritis and bacterial septicemia, which are typically 

acquired through ingestion or though exposure of open wounds.
 

Page 20 GAO-14-103 Drinking Water

• Pesticides. Under UCMR2, all public water systems serving 100,000 

or more people and a representative sample of 800 systems serving 

fewer than 100,000 people were required to monitor for nine 

pesticides using the screening survey monitoring approach. These 

pesticides included three widely used herbicides applied for weed 

control on crops such as corn, cotton, and soybeans, and six 

degradates.37 Contaminant monitoring occurred quarterly for surface 

water systems and biannually for groundwater systems. No additional 

monitoring was conducted during the seasons when pesticides were 

applied and the likelihood of occurrence was highest. Two of the 14 

experts who participated in the first round of our survey said that the 

UCMR standard monitoring frequency may result in inaccurate 

estimates of the occurrence of such pesticides in public water 

systems. For example, one expert said that, following application, 

pesticides can occur at relatively high concentrations but for short 

periods of time, and that, because the UCMR’s timing and frequency 

of monitoring are not based on this consideration, the program could 

completely miss that occurrence. Data from a United States 

Geological Survey (USGS) report also show that concentrations of 

herbicides are usually highest during and after the application season, 

primarily from April through July.38 For example, at four stream sites 

studied, USGS found that the presence of atrazine, the dominant 

herbicide used in the Corn Belt during the study period, typically 

peaked after applications in the spring and gradually declined through 

the summer and winter. According to the USGS report, such seasonal 

patterns of pesticide concentrations are generally consistent each 

 

37Specifically, the three herbicides included in UCMR2 are acetochlor, alachlor, and 

metolachlor. Such pesticides have the potential to contaminate drinking water by making 

their way into surface water or groundwater systems that feed drinking water supplies, for 

example, through runoff or drainage resulting from rainfall or irrigation. EPA classified all 

three contaminants as “possible” or “probable” carcinogens. The six degradates included 

in UCMR2 are acetochlor ethane sulfonic acid; acetochlor oxanilic acid; alachlor ethane 

sulfonic acid; alachlor oxanilic acid; metolachlor ethane sulfonic acid; and metolachlor 

oxanilic acid. Degradates are the result of pesticides breaking down in the environment as 

they interact with water, soil, air, sunlight, or microorganisms. 

38The USGS National Water-Quality Assessment Program (NAWQA) conducted a 

national-scale assessment of pesticide occurrence and concentrations in streams and 

groundwater during 1992–2001. The assessment’s findings were published in a March 

2006 report entitled, The Quality of Our Nation’s Waters—Pesticides in the Nation’s 

Streams and Ground Water, 1992–2001. The report notes that “although NAWQA did not 

measure pesticide concentrations at drinking-water intakes, NAWQA results for the wide 

range of streams sampled indicate that seasonal pulses of pesticide concentrations 

probably occur in some streams that are used as sources of drinking water.” 
 

Page 21 GAO-14-103 Drinking Water

year, as long as the pesticides are still in use. Pesticide occurrence in 

groundwater also generally coincides with pesticide use patterns. 

Sampling was conducted throughout the year, including intensive 

sampling during the times of highest pesticide use and runoff. This 

sampling approach enabled USGS to conclude that concentrations of 

pesticides in streams and groundwater were typically below waterquality benchmarks for human health. Thus, seasonal monitoring of 

pesticides is important to assess whether pesticides occur at 

concentrations that may affect human health. Also, high-frequency 

sampling during seasons when intense pesticide use coincides with 

periods of high runoff may be needed to ensure that the highest 

pesticide concentrations are detected. In contrast, EPA’s standard 

monitoring frequency requires most public water systems to monitor 

for contaminants only once per season or once over two seasons. As 

a result, some of the data collected under UCMR2 may not yield 

accurate estimates of pesticide occurrence in public water systems.

EPA used 10 selection factors, as well as a working group, and internal 

and external reviews, among other steps, to select contaminants for 

UCMR3. However, the process was lengthy due primarily to the reviews 

and the time required to develop analytical methods. The selection 

process was also limited by a statutory cap of 30 contaminants, which 

restricted EPA’s ability to collect data on additional contaminants that 

could have been monitored for very little additional cost. The selection 

process also excluded contaminants previously monitored in earlier 

UCMR cycles, which has some limitations.

To select contaminants for UCMR3, EPA considered 10 factors and used 

a prioritization process to identify potential contaminants, but took over 30 

months, or 2 1⁄2 years, to develop and publish the final list in the Federal 

Register after the CCL was published. Had EPA consistently met the 

initial and recurring statutory deadlines for CCL and UCMR, they would 

have been separated by 18 months.

EPA used 10 factors to select contaminants for UCMR3 (see fig. 1). 

Officials told us that a contaminant does not have to meet all of the 

selection factors to be chosen; however, three are very important to 

consider as follows: 

• Analytical method availability. Because analytical methods are the 

means by which laboratories test for contaminants, EPA officials told 

us they could not include a contaminant on the UCMR list without also 

EPA Considered 10 

Factors to Select 

Contaminants for 

Monitoring, but Its 

Selection Process 

Faced Limitations

UCMR3 Contaminant 

Selection Considered 

Multiple Factors, but the 

Process Was Lengthy

Contaminant Selection Factors
 

Page 22 GAO-14-103 Drinking Water

having an analytical method available that is sensitive and precise 

enough to provide the data quality and accuracy that EPA needs for 

the UCMR program. See appendix III for more information on 

analytical methods.

• Health effects information. Because of the importance of monitoring 

for UCMR contaminants that may pose a public health risk and, 

therefore, may need to be regulated, EPA officials told us they placed 

a high priority on contaminants for which they have reliable health 

effects data.

• Need for data to support regulatory determinations on priority 

contaminants. Because the goal of the UCMR program is to provide 

occurrence data on unregulated contaminants for informing regulatory 

determinations, the Standards and Risk Reduction Branch’s priorities 

for data to support a regulatory determination are heavily considered.

Figure 1: EPA Selection Factors for Identifying Contaminants for Monitoring under the Third Unregulated Contaminant 

Monitoring Rule (UCMR3)

a

EPA identified these selection factors in the Federal Register. EPA officials identified the other 

factors during interviews with us.
 

Page 23 GAO-14-103 Drinking Water

According to EPA documents and officials, EPA used a prioritization 

process to select potential UCMR3 contaminants. First, EPA considered 

the contaminants listed on CCL3 and identified contaminants of emerging 

concern39 to establish an initial list of about 150 contaminants.

Contaminants for which analytical methods were not available were then 

eliminated from consideration for UCMR3, however EPA officials told us 

that those contaminants may be monitored under a future UCMR if an 

analytical method can be developed. Contaminants that were monitored 

under UCMR1 or UCMR2 were also eliminated from further consideration 

early in the UCMR3 selection process, as reported in the Federal

Register and agency records.40 These two selection factors reduced the 

list to fewer than 35 contaminants, according to EPA documentation. In 

addition, officials told us they met regularly with representatives from the 

Standards and Risk Reduction Branch to ensure the list of UCMR 

contaminants would meet their needs for data to support regulatory 

determinations.

EPA finalized the UCMR3 list through deliberations with other EPA staff 

and stakeholders and by holding internal and external reviews, among 

other steps (see fig. 2). In November 2009, a UCMR3 working group led 

by EPA’s Technical Support Center and composed of EPA national and 

regional staff, as well as representatives from states, began to select the 

final 30 contaminants. The EPA Office of Science and Technology41

conducted health effects evaluations for possible UCMR3 contaminants, 

according to EPA documents and agency officials. The UCMR3 working 

group, whose members included experts from the Office of Science and 

Technology, reviewed this health effects information. For each UCMR3 

chemical contaminant, EPA developed an information sheet that listed 

known health effects information and the sources of that information, 

among other things. EPA used these contaminant information sheets for 

internal considerations and published them in the EPA docket for 

 

39A contaminant of emerging concern is a contaminant characterized by a perceived, 

potential or real threat to human health or the environment or by lack of published health 

standards. 

40Environmental Protection Agency, “Revisions to the Unregulated Contaminant 

Monitoring Regulation (UCMR 3) for Public Water Systems,” Proposed Rule, 76 Fed. Reg. 

11,713 (Mar. 3, 2011). 

41EPA’s Office of Science and Technology, part of the Office of Water, provides scientific 

support for drinking water regulatory determinations, information for drinking water health 

advisories, and other human health risk assessments, among other duties. 

Contaminant Selection 

Process
 

Page 24 GAO-14-103 Drinking Water

UCMR3. After the working group discussed the list of contaminants, the 

Technical Support Center submitted the proposed and final UCMR 

contaminant lists and associated rules to EPA management for their 

review. The EPA internal reviews involved different offices within EPA, 

including the Office of the EPA Administrator. EPA also submitted the 

proposed and final UCMR lists and rules to the Office of Management 

and Budget (OMB) for its review. On March 3, 2011, EPA published a 

proposed list of 30 contaminants and the associated rule in the Federal 

Register. EPA published the final UCMR3 contaminant list and associated 

rule on May 2, 2012 (see app. II for list of UCMR3 contaminants).

Figure 2: Contaminant Selection and Rule Development Process for the Third Unregulated Contaminant Monitoring Rule

The UCMR3 selection process led EPA to select many contaminants from 

the CCL, EPA’s list of the unregulated drinking water contaminants that 

may require regulation because they are known or anticipated to occur in 

public water systems. Specifically, 22 of the UCMR3 contaminants were 
 

Page 25 GAO-14-103 Drinking Water

also listed on CCL3. The CCL3 process was developed using substantial 

expert input and recommendations from various groups, including the 

National Academy of Science’s National Research Council, the National 

Drinking Water Advisory Council, and EPA’s Science Advisory Board, 

according to EPA documents. In addition, 37 of the 40 experts who 

participated in our survey said that CCL3 was a reasonable source for 

EPA to use when it began identifying contaminants for UCMR3. UCMR3 

also included 7 contaminants of emerging concern that were not on 

CCL3, and total chromium.42 Further, 33 of the 40 experts said it was 

worthwhile for EPA to select contaminants for the UCMR that are not on 

the CCL. For example, one expert in our survey told us that including 

such contaminants is the best way to identify emerging contaminants that 

come to light between the publication of the CCL and UCMR list. Overall, 

30 of the 40 experts who participated in our survey reported that the 

contaminants EPA selected for UCMR3 warrant monitoring.

EPA’s UCMR3 contaminant selection and rule development process took 

more than 2 1⁄2 years to complete. EPA started the formal UCMR3 

selection process in November 2009 but did not publish the final UCMR3 

list until May 2012. SDWA specifies that EPA publish a new UCMR list 

every 5 years. Whereas EPA’s previous list was issued in 2007, it met the 

5-year time frame required by SDWA. However, the UCMR program is no 

longer staggered 18 months after the CCL, as SDWA intended. Rather, 

UCMR3 was issued 31 months after CCL3. Based on the length of its 

process, EPA would have had to begin selecting contaminants in 

September 2008 to have issued UCMR3 within 18 months of CCL3. 

Further, EPA cannot implement the UCMR program until it publishes the 

final UCMR list and rule in the Federal Register, which delays the onset of 

the data collection period. This delay, in turn, delays the availability of the 

UCMR data for making regulatory determinations (see fig. 3).

 

42 Total chromium, while already regulated in drinking water, was included in conjunction 

with UCMR3 monitoring to determine its relationship with chromium-6, a contaminant of 

emerging concern. 

Contaminant Selection 

Process Was Lengthy
 

Page 26 GAO-14-103 Drinking Water

Figure 3: UCMR3 Timeline

The UCMR3 contaminant selection and rulemaking process concluded 31 

months after the CCL was issued primarily because EPA waited to initiate 

its working group until CCL3 was finalized, and the EPA and OMB 

reviews were lengthy. First, EPA’s UCMR3 working group did not begin 

its work until November 2009, after the final CCL3 had been published in 

October 2009. EPA officials told us that discussions about potential 

contaminants for UCMR3 and analytical methods that were likely to be 

available to detect them began earlier, but they waited until November 

2009 to begin the formal selection process, in part, because of staffing 

needs. The staff who developed UCMR3 were also coordinating and

providing technical support to the public water systems that were 

monitoring for contaminants under UCMR2, which took place between 

January 2008 and December 2010. In addition, CCL staff serve on the 

UCMR working group, and UCMR staff also serve on the CCL working 

group, which EPA officials told us limits their availability. Second, EPA 

internal reviews, OMB reviews, and the revisions to the UCMR3 proposed 

and final rules prompted by the reviewers’ comments added 16 months in 

total to the process. However, these reviews are not always required for 

this type of activity, according to agency guidance. Specifically, EPA’s 

UCMR is conducted under the agency’s Action Development Process, a 

process used for developing rules. The agency incorporated EPA 

management and OMB reviews into their process; however, these 
 

Page 27 GAO-14-103 Drinking Water

reviews are not always required for a program like the UCMR, according 

to agency guidance, as stated earlier.

43

In addition, the EPA analytical method development process is complex, 

technically challenging and lengthy, which agency officials also told us 

presents a challenge for EPA to meet its deadline. EPA officials said it 

typically takes 1 to 2 years to develop a standard method that meets the 

requirements needed for the UCMR program and up to 3 years or longer 

for more complex methods. In addition, EPA generally has not used a 

specific analytical method in more than one UCMR cycle, although some 

of those older methods could be used to monitor unregulated 

contaminants for which EPA does not yet have UCMR occurrence data.

For example, an analytical method used under UCMR1 could have 

detected seven CCL3 contaminants, but this method was not included in 

UCMR3. According to industry organizations and EPA officials, EPA did 

not formally reach out to stakeholders when developing analytical 

methods for UCMR 1, 2, or 3. However, EPA is formally reaching out to 

stakeholders to get their input on the development of analytical methods 

that may be used for UCMR4. In May 2013, EPA held a public meeting 

and webinar to provide stakeholders with an update on analytical 

methods that EPA has completed or has under development for potential 

use in the UCMR program and requested input from attendees to help 

address some of the technical challenges it faces. 

The statutory cap limiting the UCMR program to 30 unregulated 

contaminants every 5 years (i.e., each UCMR cycle) impedes EPA’s 

ability to obtain occurrence data on additional contaminants that could be 

monitored for little additional effort or cost. Many of the analytical methods 

that EPA is using for UCMR3 are able to test a single sample of drinking 

water for more than one contaminant at a time. Therefore, data on 

additional contaminants could be obtained without additional sampling by 

the public water systems. EPA is allowing laboratories to use eight EPAdeveloped analytical methods to test for UCMR3 contaminants and four 

methods developed by others. These methods can detect a total of 67 

unregulated contaminants, including 4 listed on CCL3 and 8 contaminants 

of emerging concern, according to our analysis of EPA data. There is 

 

43EPA classified the UCMR program as a Tier 3 action under its Action Development 

Process. Tier 3 actions allow the lead office to design their own review processes and do 

not require formal EPA management reviews or OMB reviews. 

Statutory Cap of 30 

Contaminants Limits EPA’s 

Ability to Obtain Additional 

Data at Little Extra Cost
 

Page 28 GAO-14-103 Drinking Water

broad recognition throughout the federal government that agencies need 

to operate programs efficiently and maximize efficiencies when possible.44

In addition, EPA officials who use the UCMR data to make regulatory 

determinations, while sensitive to the practical limitations of monitoring for 

additional contaminants, said that it would be helpful to have additional 

UCMR data if a method already in use for UCMR could detect the 

occurrence of additional contaminants. However, because of the SDWA 

limit of 30 contaminants, EPA cannot always take advantage of this 

efficiency and is unable to gain economies of scale by monitoring for 

additional contaminants using monitoring that is already under way.

Specifically, our analysis indicates that four CCL3 chemicals—1,1,1,2-

Tetrachloroethane; n-propylbenzene; sec-butylbenzene; and methyl 

tertiary-butyl ether (MTBE)—could have been detected using one of the 

UCMR3 analytical methods. As noted earlier, CCL3 represents EPA’s list 

of the unregulated drinking water contaminants that may require 

regulation because they are known or anticipated to occur in public water 

systems. EPA had included n-propylbenzene and sec-butylbenzene in the 

proposed list of UCMR3 contaminants, but it did not include them on the 

final UCMR3. Instead, EPA included chromium-6, as well as total 

chromium, which EPA stated became higher priorities for monitoring for 

the agency. Public comments on the draft UCMR3 list also supported 

monitoring these two contaminants. EPA’s Standards and Risk Reduction 

Branch, which develops the regulatory determinations, supported the 

inclusion of the two chromiums, as did a majority of the experts who 

participated in our survey (35 of 40 supported adding chromium-6 and 28 

of 40 supported adding total chromium). However, by including these two 

higher priority contaminants, EPA removed two others in light of the cap 

of 30 contaminants and could not take advantage of economies of scale 

by using a method already selected for UCMR3 to obtain additional data.

In addition, MTBE could also have been monitored using the same 

method. However, EPA officials told us they decided not to include 

MTBE, which was monitored under UCMR1, because they did not need 

 

44Given continuing budget pressures combined with the focus on performance envisioned 

in the GPRA Modernization Act of 2010, we have reported that federal agencies need to 

identify ways to operate more efficiently. We have defined efficiency as maintaining 

federal government services or outcomes using fewer resources (such as time and 

money) or improving or increasing the quality or quantity of services or outcomes while 

maintaining (or reducing) resources. See GAO, Streamlining Government: Key Practices 

from Select Efficiency Initiatives Should be Shared Governmentwide, GAO-11-908

(Washington, D.C.: Sept. 30, 2011). 
 

Page 29 GAO-14-103 Drinking Water

additional information about it. As noted earlier, the priorities of EPA’s 

Standards and Risk Reduction Branch are a key selection factor for which 

contaminants to include on the UCMR. In the absence of the limit of 30, 

EPA would have had an opportunity to monitor for these CCL3 chemicals, 

as well as 1,1,1,2-Tetrachloroethane, as part of UCMR3 at nominal extra 

cost. EPA officials told us that adding a contaminant to an ongoing

analysis typically costs about $5 to $10.

Similarly, our analysis indicates that eight contaminants of emerging 

concern known as perfluorinated chemicals, or PFCs, could also have 

been detected by the same analytical method that EPA is using to 

monitor six other PFCs (see table 5).45 In 2009, EPA published an action 

plan to address some of these chemicals, which the agency describes as 

persistent in the environment and in people.46 This action plan also states 

that it can reasonably be anticipated that continued exposure to PFCs 

could harm human health. Due to industry’s increasing use of various 

PFCs, EPA included six of the chemicals identified in this plan in UCMR3, 

according to EPA officials. However, according to our analysis, five 

additional PFCs from the plan are among the eight that could have been 

detected using the same analytical method but are not on UCMR3. EPA 

selected the six PFCs it thought most important, but the statutory limit of 

30 contaminants curtailed EPA’s opportunity to gather occurrence data on 

eight additional contaminants of emerging concern at little additional cost 

or effort. EPA could have included the additional PFCs in UCMR3 but 

doing so would have reduced the number of contaminants selected from 

CCL3, EPA’s list of the unregulated drinking water contaminants that may 

require regulation because they are known or anticipated to occur in 

public water systems. Nonetheless, the agency will not have UCMR data 

on whether or not those eight contaminants are present in the nation’s 

drinking water until the next UCMR cycle at the very earliest; UCMR4 

data collection is expected to be completed in 2021. However, EPA has 

not decided which contaminants will be monitored under UCMR4, and so 

it remains to be seen if they are included.

 

45PFCs are man-made chemicals that are used in a wide variety of industrial and 

commercial products. EPA has reported that PFCs have significant adverse effects on 

laboratory animals and wildlife and anticipates that continued exposure to PFCs could 

result in adverse effects on humans.

46Environmental Protection Agency, Long-Chain Perfluorinated Chemical’s (PFCs) Action 

Plan (Washington, D.C.: Dec. 30, 2009). 
 

Page 30 GAO-14-103 Drinking Water

Table 5: Contaminants of Emerging Concern Detectable with an Analytical Method 

Already in Use 

Contaminants of emerging concern 

N-Ethyl perfluorooctanesulfonamido acetic acid

N-Methyl perfluorooctanesulfonamido acetic acid

Perfluorodecanoic acid 

Perfluorododecanoic acid 

Perfluorohexanoic acid 

Perfluorotetradecanoic acid 

Perfluorotridecanoic acid 

Perfluoroundecanoic acid 

Source: GAO analysis of EPA data.

Note: All of the contaminants of emerging concern listed in this table are perfluorinated chemicals, or 

PFCs. PFCs are man-made chemicals that are used in a wide variety of industrial and commercial 

products. EPA has reported that PFCs have significant adverse effects on laboratory animals and 

wildlife and anticipates that continued exposure to PFCs could result in adverse effects on humans.

The legislative history of the SDWA Amendments of 1996 generally noted 

concerns with the financial limitations of public water systems and their 

abilities to absorb costs for activities such as monitoring. While the 

number of contaminants being monitored is a factor, costs related to 

analytical methods, such as laboratory equipment and labor, are key cost 

drivers for UCMR monitoring, according to EPA officials. EPA officials told 

us that they carefully consider the cost on public water systems when 

selecting analytical methods for the UCMR program. In addition, EPA 

pays for some of the small public water systems’ monitoring and must 

stay within its budget for those costs.47 EPA documentation indicates that 

UCMR3 will generally cost public water systems $50 to $470 per water 

sample, per analytical method. EPA officials told us that the cost to detect 

additional contaminants for an analytical method already in use was 

nominal—typically about $5 to $10 per water sample, per contaminant. 

Thus, the cost of adding contaminants to an analytical method that is 

already being used would likely pose only a modest cost increase for 

public water systems.

 

47EPA has funded the small public water system’s UCMR monitoring from EPA’s State 

Revolving Fund appropriation. 
 

Page 31 GAO-14-103 Drinking Water

One of EPA’s key selection factors for UCMR3 involved generally 

eliminating contaminants that were monitored under a prior UCMR 

round,48 but by eliminating those contaminants, EPA may encounter data 

limitations because (1) the sampling methodology was not sufficient, (2) 

the health information has been updated, or (3) the data have become 

outdated.

Sampling methodology. One of the sampling methodologies EPA used in 

a prior UCMR did not provide sufficient occurrence data to make 

regulatory determinations for some contaminants, according to EPA’s 

regulatory determinations for the CCL2 contaminants.49 Specifically, 

UCMR1 used a limited sample size of 300 public water systems for the 14 

contaminants it monitored using the screening survey approach. This 

resulted in occurrence data for some contaminants that, according to EPA 

documents, were not sufficient to make a national estimate. In its July 

2008 Regulatory Determination notice, EPA found that a total of 12 

contaminants monitored under UCMR1 had insufficient occurrence data 

for making national estimates. Three of those contaminants are also listed 

on CCL3—the pesticides disulfoton, diuron, and terbufos. By applying the 

UCMR selection factor to eliminate contaminants monitored under 

previous UCMR rounds, EPA did not consider remonitoring these 

contaminants in UCMR3, even though EPA previously found the existing 

data were not sufficient to make national estimates of contaminant 

occurrence. However, 31 of the 40 experts who participated in our survey 

said it would be worthwhile to monitor UCMR contaminants again if they 

had insufficient data due to the sampling size.

According to EPA’s notice in the Federal Register for UCMR1, EPA’s 

original intent was to use the screening survey as a first indicator of 

potential contamination and then to remonitor the contaminants again 

using assessment monitoring to obtain nationally representative results if 

the contaminants occurred frequently enough in drinking water to warrant 

 

48EPA has only once remonitored for a contaminant: namely, the pesticide acetochlor, 

which was monitored under UCMR1 and UCMR2. MTBE was monitored under UCMR1 

and was considered for, but not included, in UCMR3. EPA’s practice when selecting 

contaminants for UCMR3 was to exclude those monitored under a prior UCMR, as stated 

in the Federal Register. 

49Environmental Protection Agency, “Drinking Water: Regulatory Determinations 

Regarding Contaminants on the Second Drinking Water Contaminant Candidate List,” 

Final Rule, 73 Fed. Reg. 44,251 (July 30, 2008). 

UCMR3 Excludes 

Previously Monitored 

Contaminants
 

Page 32 GAO-14-103 Drinking Water

doing so.50 However, EPA officials told us they later determined that this 

approach was not feasible because of the time it required and did not 

follow through with its plan to remonitor the UCMR1 contaminants. For 

the UCMR2 and UCMR3 cycles, EPA revised its approach and increased 

the screening survey sample size from 300 to 800. Specifically, under 

UCMR1, the screening survey included a sample of 300 public water 

systems.51 Under UCMR2 and UCMR3, the screening survey included a 

sample of 800 public water systems and all of the systems serving more 

than 100,000 people, for a total of approximately 1,200 systems.

52 This 

increase allowed EPA to make nationally representative estimates based 

on the occurrence data.

Health effects information. According to EPA officials, health effects 

information for unregulated contaminants is often uncertain and in flux 

because research is often being conducted at the same time UCMR 

monitoring is occurring. Those officials said the new research sometimes

indicates that health effects occur at lower levels of exposure than 

previously thought. In recognition of this, EPA set the monitoring levels, or 

MRLs, for UCMR3 based on how low the analytical method could reliably 

measure specific contaminants, as reported earlier. However, EPA 

previously set the MRLs for UCMR1 and UCMR2 with consideration of 

the levels of public health concern that were known at the time. In May 

2011, we reported that EPA set the MRLs for some of the UCMR1 and 

UCMR2 contaminants before it had developed the health reference levels 

for those contaminants. EPA subsequently determined that those MRLs 

exceeded the health reference levels. As a result, occurrence of those 

contaminants at a level higher than the health reference level but lower 

than the MRL might not have been detected, and UCMR1 and UCMR2 

occurrence data might not accurately capture the risk these contaminants 

pose to public health. Similarly, if the health effects information about the 

UCMR1 and UCMR2 contaminants changes in the future, EPA may not 

 

50Environmental Protection Agency, “Revisions to the Unregulated Contaminant 

Monitoring Regulation for Public Water Systems,” Final Rule, 64 Fed. Reg. 50,556, 50,568 

(Sept. 17, 1999). 

51The 300 public water systems included 120 systems serving more than 10,000 people 

and 180 systems serving 10,000 or fewer people. 

52The 800 public water systems included 320 systems serving 10,001 to 100,000 people; 

and a representative sample of 480 systems serving 10,000 or fewer people. 

Approximately 400 systems serve more than 100,000 people. 
 

Page 33 GAO-14-103 Drinking Water

have the data it needs to support regulatory determinations. Thirty-two of 

the 40 experts who participated in our survey said it would be worthwhile 

to monitor again for UCMR1 and UCMR2 contaminants if new health 

effects information becomes available.

Age of data. The UCMR data estimated contaminant occurrence at the 

time that they were collected. Due to changing industrial and agricultural 

chemical use and environmental conditions, UCMR data may not present 

an accurate picture of current contaminant occurrence after several 

years. In particular, the UCMR1 data, which were collected from 2001 to 

2003, are now over 10 years old. Nineteen of the 40 experts who 

participated in our survey said that UCMR data this old are not likely to be 

a reliable indicator of the frequency and level of drinking water 

contamination, and 18 said they did not have enough information to judge 

how long the UCMR data are likely to be a reliable indicator. EPA officials 

and experts told us the shelf life of the UCMR data generally depends on 

the type of contaminant and whether its use is likely to have changed 

over time. According to the officials, concentrations of naturally occurring 

contaminants remain relatively constant in drinking water over time but 

concentrations of pesticides and industrial chemicals are subject to 

change. While some of the UCMR1 data may still be a reliable indicator of 

contaminant occurrence, several of the UCMR1 contaminants are 

pesticides and industrial chemicals and the extent of their use has 

changed since the UCMR data were collected. For example, use of the 

pesticides disulfoton and molinate effectively ended following EPA actions 

in 2009 and 2004, respectively.53 Use of the pesticides terbufos and 

diuron also decreased significantly from 2003 to 2009, according to 

USGS data. In addition, use of two industrial chemicals, MTBE and 

nitrobenzene, decreased over time, according to EPA data. MTBE, a 

former gasoline additive, has not been used in significant quantities since 

2005. Nitrobenzene use has fluctuated over time but decreased sharply 

from 1998 to 2005.54 Because the UCMR1 data estimate contamination at 

a point in time prior to these changes, they likely overestimate current 

levels of contaminant occurrence.

 

53In 2009, EPA cancelled the registration for disulfoton. In 2004, EPA cancelled certain 

uses of molinate. Molinate is still registered but, as of 2012, there were no active uses, 

according to EPA documents. 

54EPA’s data do not indicate whether the decrease in nitrobenzene use occurred before, 

during, or after the UCMR1 data were collected.
 

Page 34 GAO-14-103 Drinking Water

EPA might choose not to make regulatory determinations on some 

contaminants if it concludes that the available occurrence data do not 

provide sufficient support, as it did for several contaminants in 2008. As 

we reported in May 2011, EPA did not make regulatory determinations for 

some contaminants monitored under a prior UCMR round because the 

occurrence data were not sufficient to do so.55 SDWA requires EPA to 

use the best available data,

56 but by not remonitoring contaminants when 

appropriate, such as when the data collected in an earlier cycle have 

become outdated, EPA may not have sufficient data to support its 

regulatory determinations. SDWA does not prohibit EPA from 

remonitoring UCMR contaminants; therefore, the agency has the option 

to do so, for example when it believes that remonitoring would provide 

better support for its regulatory determinations. EPA officials told us that 

when developing future UCMRs, they will consider whether adequate 

occurrence data for a contaminant had already been collected under a 

prior UCMR, rather than generally eliminating all previously monitored 

contaminants as part of its contaminants selection process. They also 

said that if the officials who make the regulatory determinations asked for 

a contaminant to be remonitored, they would consider doing so.

 

55 In May 2011, we reported that EPA had not defined what data are adequate to support 

a regulatory determination. In that report, we also recommended that EPA develop 

guidance for making regulatory determinations that included factors for determining when 

data provide adequate support. In its response to the recommendation, EPA stated that it 

did not believe establishing such guidance was practicable, given the many combinations 

of health effects factors and potential ranges of frequencies and levels of contaminants 

measured in drinking water.

56SDWA requires EPA, in carrying out the provisions concerning listing, selecting, and 

regulating contaminants, to the degree that an action is based on science, to use the best 

available peer-reviewed science and data collected by accepted or best available 

methods. 
 

Page 35 GAO-14-103 Drinking Water

EPA uses the UCMR data to support regulatory determinations but faces 

a time lag when doing so. Agency officials told us UCMR data are EPA’s 

primary source of data on the occurrence of unregulated contaminants in 

drinking water and are a key input for regulatory determinations. 

However, by the time the complete set of UCMR data is available, the 

recurring 5-year deadline SDWA established for making at least 5

regulatory determinations has passed, leading EPA, in some cases, to 

rely on older data that may no longer accurately reflect current

contaminant occurrence in drinking water.57

EPA uses the UCMR data, along with information about the 

contaminants’ health effects and other information, to make regulatory 

determinations—that is, decisions on whether or not new primary drinking 

water standards are needed for particular unregulated contaminants. 

Regulatory determinations can be positive (i.e., a new primary standard is 

needed) or negative (i.e., no new primary standard is needed).58 While 

SDWA requires EPA to make regulatory determinations for at least five 

CCL contaminants every 5 years, EPA officials told us their goal is to 

make as many regulatory determinations as possible, given the available 

data.59 EPA used UCMR1 data to support 9 of the 11 regulatory 

determinations it made in 2008 for the CCL2 contaminants and another 

regulatory determination in 2011. It is currently using UCMR1 and 

UCMR2 data to inform its regulatory determinations for the CCL3 

contaminants, which EPA expects to issue in 2015. The complete 

UCMR3 data set will not be available until after those regulatory 

determinations have been issued. However, if the timing allows, EPA 

officials told us they may have an opportunity to use a partial UCMR3 

data set to corroborate other data they have on contaminant occurrence

when making the final regulatory determinations.

 

57SDWA requires EPA to make at least 5 regulatory determinations every 5 years, and 

hence we refer to the 5-year mark as a “deadline.” See 42 U.S.C. § 300g-1(b)(1)(B)(ii)(I) 

(2013). 

58EPA has made 20 negative regulatory determinations and 1 positive regulatory 

determination (perchlorate) since the SDWA Amendments of 1996 established the UCMR 

program. 

59EPA also needs information on a contaminant’s health effects to make a regulatory 

determination. In 2011, GAO reported that EPA did not have health effects information for 

many of the contaminants on the CCL, which limited EPA’s ability to make regulatory 

determinations. See GAO-11-254. 

UCMR Data Support 

Regulatory 

Determinations, but 

Time Lag Results in 

Delays and Reliance 

on Older Data

UCMR Data Are EPA’s 

Primary Occurrence Data 

Source and a Key Input for 

Regulatory Determinations
 

Page 36 GAO-14-103 Drinking Water

EPA officials told us that, when they are available, UCMR data are EPA’s 

primary data source on unregulated contaminants in drinking water 

because they allow EPA to make national estimates of drinking water 

contamination, as discussed earlier in this report. EPA also has data on 

unregulated contaminants from other sources, such as USGS and some 

states, but those data do not provide nationally representative estimates 

of drinking water contamination. For example, the USGS data estimate 

contamination in source water (i.e., untreated water from rivers, lakes, 

and groundwater aquifers). Since source water can become public 

drinking water, the USGS data can indicate potential drinking water 

contamination. However, these data do not provide conclusive 

information on whether contamination is occurring in public water 

systems. EPA officials told us they use the other data to provide 

additional support for regulatory determinations, but they generally do not 

provide sufficient support on their own. In contrast, the UCMR data are 

generally sufficient for estimating nationwide occurrence of drinking water 

contamination, with the exceptions noted earlier in this report. In addition, 

35 of the 40 experts who participated in our survey said that the UCMR 

program has been an effective way to collect sufficient data to determine 

whether contamination is occurring frequently and at levels of public 

health concern in drinking water. Several experts provided additional 

comments on the overall effectiveness of the UCMR program. For 

example, one expert said that considering the great need for data and 

EPA’s limited resources, the UCMR program has been one of the more 

effective tools in the agency’s rule development process. Another expert 

said that, given statutory requirements, resources, and data availability, 

EPA has done an admirable job with the UCMR program. Finally, one 

expert said that the UCMR program has been an effective way to remove 

contaminants from the radar screen when they did not warrant regulation.

A time lag between the SDWA deadline for regulatory determinations and 

the UCMR data’s availability typically delays determinations on given 

contaminants by a full 5-year cycle. SDWA sets deadlines for publishing 

the CCL and UCMR contaminant list and making regulatory 

determinations, but it does not set a deadline for monitoring the UCMR 

contaminants. SDWA established recurring 5-year deadlines for making 

regulatory determinations and for publishing the UCMR list. EPA has 

established a 3-year monitoring period for the UCMR, but this overlaps 

with the time frame during which EPA makes its regulatory 

Time Lag Delays 

Regulatory Determinations 

by a Full 5-Year Cycle and 

Results in the Use of 

Older Data
 

Page 37 GAO-14-103 Drinking Water

determinations. EPA also uses some older data that may no longer 

accurately reflect current contaminant occurrence in drinking water when 

it is making regulatory determinations.60

A time lag between the statutory deadline for regulatory determinations 

and the UCMR data’s availability typically delays regulatory 

determinations on given contaminants until the following cycle. SDWA 

directs EPA to publish a new CCL, UCMR, and set of regulatory 

determinations every 5 years, as described earlier in this report. The 

initial timeline staggered the deadlines such that EPA was required to 

publish the UCMR list 18 months after the CCL and issue the regulatory 

determinations 2 years after that. However, in practice, the 2-year window 

SDWA set from the time EPA publishes the UCMR list to when it makes 

regulatory determinations has not provided enough time for the agency to 

monitor the contaminants and incorporate the UCMR data into the 

determinations. Consequently, UCMR data are not available for EPA to 

make regulatory determinations for contaminants during the cycle in 

which they are monitored; rather, UCMR data for contaminants in one 

cycle typically are not used until the next cycle or later (see fig. 4).

 

60In its comments on a draft of this report, EPA noted that the agency makes judgments 

on a case by case basis to determine whether data are too old. 

Time Lag Typically Delays 

Regulatory Determinations for 

Contaminants by a Full 5-Year 

Cycle
 

Page 38 GAO-14-103 Drinking Water

Figure 4: UCMR Data Do Not Inform Regulatory Determinations in the Same Cycle

EPA officials told us that the timing of the UCMR program is a key 

challenge, particularly in relation to the timing of the CCL and regulatory 

determination deadlines. Since the UCMR program began, the full UCMR 

data set has not been available until a year or more after EPA made its 

regulatory determinations for the same 5-year cycle. The time lag is 

influenced by the recurring 5-year deadlines for the CCL, UCMR, and 

regulatory determinations and increased when EPA missed the deadlines 

for CCL2 and UCMR2. As a result, UCMR2 data were not available until 

nearly 3 years after EPA made the regulatory determinations for the 

CCL2 contaminants. When EPA missed the UCMR2 deadline, 

subsequent deadlines were moved to a later date, consistent with the 5-
 

Page 39 GAO-14-103 Drinking Water

year cycle established by SDWA.61 Accordingly, the UCMR3 data will lag 

behind the regulatory determinations for the CCL3 contaminants by over 

a year. Based on EPA’s current schedules for the three programs, the 

UCMR4 data will likewise lag behind the regulatory determinations for the 

CCL4 contaminants. EPA’s schedule indicates that the agency plans to 

make regulatory determinations for the CCL4 contaminants in spring 

2020 and complete UCMR4 monitoring in December 2020, with the full 

UCMR4 data set available in 2021. Without congressional action to make 

the time frames more realistic, the time lag and resultant delays are 

expected to continue in subsequent cycles.

EPA has established a 3-year monitoring period for the UCMR, which 

contributes to the time lag between the SDWA deadline for regulatory 

determinations and the UCMR data’s availability. Before the monitoring 

period begins, EPA spends about 1 year preparing for the monitoring that 

public water systems will conduct. During this time, EPA finalizes the 

monitoring schedules for systems that will be participating in the program 

and approves the laboratories that will conduct the analyses, among other 

things. Each public water system monitors for contaminants during a 12-

month window throughout the 3-year period that follows. EPA officials told 

us they spend up to 1 year finalizing the data collection and analysis, 

which includes about 6 months for public water systems and laboratories 

to report, review, and approve their data.62 The UCMR3 monitoring, data 

collection, and analysis overlap with the time frame during which EPA will 

be making its regulatory determinations for contaminants on CCL3. 

UCMR3 monitoring is occurring from January 2013 through December 

2015. Regulatory determinations for the CCL3 contaminants are expected 

in spring 2015, according to agency officials.63 Officials who make the 

regulatory determinations told us that it is helpful to have the UCMR data 

 

61SDWA limits EPA to listing no more than 30 contaminants every 5 years and, as a 

result, EPA cannot accelerate the UCMR schedule by issuing the next list earlier–that is, 

before 5 years from the last one–under current law. Each time EPA publishes a UCMR list 

or set of regulatory determinations, the agency adds 5 years to determine its next 

deadline. 

62EPA had considered shortening the time to report, review, and approve the data by 

about half (90 days total) but decided not to, based on public comments on the proposed 

UCMR3 rule and OMB’s review of the final rule. 

63Final regulatory determinations for the CCL3 contaminants were originally expected to 

be published in 2013, according to EPA documents. However, EPA officials told us they 

have been delayed until 2015 for reasons unrelated to the UCMR program. 

Three-Year Monitoring Period 

Contributes to Time Lag
 

Page 40 GAO-14-103 Drinking Water

about 2 years before publishing the final regulatory determinations. They 

also told us they start using the data once about 70 percent of the data 

set is available, approximately 2 years into the 3-year monitoring period. 

For example, EPA began using the UCMR1 data set to inform its internal 

deliberations on the regulatory determinations for CCL2 after about 70 

percent of the data were available, according to agency officials. The 

officials said that by this time in the data collection period they saw very 

little variation in contaminant occurrence (i.e., the data were relatively 

stable). 

EPA officials told us they selected the 3-year monitoring period mainly for 

logistical reasons impacting the agency and the public water systems. 

They told us that the 3-year monitoring period spreads the agency’s work 

out over a more manageable period of time. EPA staff provide technical 

support to the public water systems conducting the monitoring, and many 

also have other responsibilities, according to EPA officials. The 3-year 

monitoring period also provides public water systems with more flexibility 

to decide when they will start monitoring. EPA officials told us that, after 

the agency publishes the final UCMR in the Federal Register, they assign 

each system a month and year to start monitoring. However, some 

systems request a later start date to incorporate the monitoring into their 

budgets and operations, according to agency officials. EPA officials also 

said laboratory capacity is sufficient under the 3-year period and has 

approved 53 laboratories to participate in UCMR3. EPA officials had told 

us that about 15 laboratories could probably handle the analytical work for 

UCMR3, therefore, laboratory capacity may be sufficient under a shorter 

monitoring period. Officials also told us that the 3-year monitoring period 

is not a given. For example, officials told us that a 2-year monitoring 

period, while challenging, may be possible for future cycles, but they 

would have to evaluate the shorter time frame in detail to determine its 

feasibility.

UCMR program officials also told us that monitoring over 3 years is 

intended to allow them to account for the effects that extreme weather in 

a given season could have on the data. They told us they did not know 

whether a shorter monitoring period, such as a 2-year period, would also 

allow them to do this because the extent of seasonal variability in the 

UCMR program is unknown. However, they did not expect that a shorter 

monitoring period would address variability to the same extent that the 

current 3-year monitoring period would because the longer period of time 

provides greater opportunity to detect it. Nonetheless, as reported earlier, 

EPA officials who make the regulatory determinations observed very few 

changes in occurrence trends after about 70 percent of the UCMR data 
 

Page 41 GAO-14-103 Drinking Water

had been collected, about 2 years into the 3-year monitoring period. 

When asked, experts who participated in our survey had mixed views on 

whether a 2-year monitoring period would be likely to provide EPA with 

sufficient information on seasonal fluctuations.64 Specifically, 19 of 40 

respondents thought that it was likely to, 11 thought it was not likely to, 

and 9 said they did not have enough information to judge. The UCMR3 

data set may provide EPA with information that it can use to assess the 

extent of seasonal variability, according to agency officials. Because 

UCMR3 is monitoring for contaminants at low MRLs, it will likely have a 

higher rate of detections than prior UCMRs and, therefore, more data 

points that EPA can use to detect seasonal variability that it would have 

missed in the past. EPA could use this information to help it understand 

the extent of seasonal variability and the feasibility of a shorter monitoring 

period.

EPA has adapted to the time lag by using UCMR data from previous 

cycles to make regulatory determinations. For example, EPA is using 

UCMR1 and UCMR2 data to make regulatory determinations for the 

CCL3 contaminants.65 Similarly, EPA used UCMR1 data to make 

regulatory determinations for the CCL2 contaminants. Because EPA has 

carried over many contaminants from one CCL to the next, officials told 

us this is a workable approach.66 However, more than half of the experts 

(25 of 40) who participated in our survey did not think using data from a 

prior UCMR cycle was an effective strategy for making regulatory 

determinations. Many of those experts were concerned because the time 

lag delays regulatory determinations on given contaminants and leads 

EPA to use older data that may not reflect current contaminant 

occurrence in some cases. The time lag delays regulatory determinations 

on contaminants by at least one 5-year cycle, and sometimes longer. 

EPA officials told us that most of the UCMR3 data will be used to support 

regulatory determinations for the CCL4 contaminants, which are expected 

 

64Survey on EPA’s Unregulated Contaminant Monitoring Program, Question 19B: For the 

30 contaminants being monitored under UCMR-3, would a 2-year monitoring timeframe 

instead of the 3-year timeframe be likely to provide EPA sufficient information on seasonal 

fluctuations in contaminant occurrence? (See app. IV for full survey.) 

65As noted earlier, EPA may have an opportunity to use partial UCMR3 data to inform its 

CCL3 regulatory determinations, but not enough UCMR3 data will be available to serve as 

a primary source. 

66Eighteen of the contaminants on CCL3 were carried over from CCL1 and CCL2. 

EPA Uses Occurrence Data 

from Previous UCMR Cycles 

When Current Data Are Not 

Available
 

Page 42 GAO-14-103 Drinking Water

to be issued in 2020. Those UCMR3 contaminants that are carried over to 

CCL4 will wait about 10 years for regulatory determinations unless EPA 

uses data from another source or makes an out-of-cycle regulatory 

determination (see fig. 5).67

Figure 5: About 10 Years Typically Pass before Regulatory Determinations Are Made for Contaminants on the CCL

a

Contaminant “A” not considered because UCMR data are not yet available.

Regulatory determinations on given contaminants can also take longer to 

make. For example, 11 of the contaminants EPA included on a short list 

of potential regulatory determinations for CCL368 were first listed on CCL1 

in March 1998.69 By the time EPA makes its regulatory determinations, 

about 17 years will have passed since they were identified as 

contaminants known or anticipated to occur in public water systems. In 

addition, there are six contaminants that EPA carried over from CCL1 to 

 

67EPA can make regulatory determinations outside of the 5-year cycle but has done so 

only once. In 2011, EPA made an out of cycle determination to regulate perchlorate. 

68Environmental Protection Agency, “Regulatory Determinations for the Third Drinking 

Water Contaminant Candidate List, Presentation for Stakeholder Meeting” (Washington, 

D.C.: June 16, 2011). 

69EPA first listed these contaminants on CCL1 and carried them over to CCL2 and CCL3.

They are (1) acetochlor, (2) alachlor ESA, (3) disulfoton, (4) diuron, (5) MTBE, (6) 

metolachlor, (7) molinate, (8) nitrobenzene, (9) RDX, (10) terbufos, and (11) vanadium. 
 

Page 43 GAO-14-103 Drinking Water

CCL3 that it has not yet included in a regulatory determinations cycle. 

UCMR data are not yet available for any of them, although two—methyl 

bromide and 1,1-dichloroethane—are currently being monitored under 

UCMR3.70 Methyl bromide is a pesticide that was phased out of use in 

2005; 1,1,-dichloroethane is an industrial chemical. Due to the time lag, 

EPA’s first use of the UCMR3 data for these CCL1 contaminants will 

likely be when it makes the regulatory determinations for CCL4.71 This is 

about 22 years after they were first identified on the CCL as unregulated 

contaminants that are known or anticipated to occur in public water 

systems and may require regulation.

EPA is also using some older UCMR data that may not accurately reflect 

current contaminant occurrence in drinking water to make regulatory 

determinations, according to agency documents. Specifically, 6 of the 32 

contaminants EPA included on its short list of potential regulatory 

determinations for CCL3 were monitored from 2001 to 2003 under 

UCMR1.72 EPA officials told us that one of the reasons the UCMR1 data 

were not used for the regulatory determinations it issued in 2008 was 

because health effects information on some of the contaminants was not 

available.73 EPA’s July 2008 regulatory determinations indicate that there 

were health effects information gaps for 3 of the 6 contaminants.74 As 

noted earlier in the report, the UCMR1 data are now over 10 years old 

and may not accurately reflect current levels of drinking water 

contamination in some cases. In particular, the 6 UCMR1 contaminants 

on EPA’s short list are industrial chemicals and pesticides, and the extent 

 

70The other four contaminants are microbes and have not been monitored yet because 

EPA does not have analytical methods available for them. Methyl bromide is listed by the 

name bromomethane in UCMR3. 

71While EPA is authorized to make regulatory determinations outside of the 5-year cycle, 

in practice, it has done so only once. 

72These contaminants are (1) disulfoton, (2) diuron, (3) MTBE, (4) molinate, (5) 

nitrobenzene, and (6) terbufos. 

73We have previously reported that gaps in health effects data limit EPA’s ability to make 

regulatory determinations and recommended that EPA develop a coordinated process for 

obtaining the necessary health effects and occurrence data. EPA’s response to our 

recommendation did not acknowledge that any further steps are needed. See 

GAO-11-254. 

74Environmental Protection Agency, “Drinking Water: Regulatory Determinations 

Regarding Contaminants on the Second Drinking Water Contaminant Candidate List,” 73 

Fed. Reg. 44,251 (July 30, 2008). 
 

Page 44 GAO-14-103 Drinking Water

of their use has changed since the UCMR data were collected, as 

described earlier. Four of the 6 contaminants are pesticides: disulfoton, 

molinate, terbufos, and diuron. The other 2 contaminants are industrial 

chemicals: MTBE and nitrobenzene. Further, in its July 2008 Regulatory 

Determination notice, EPA stated that it had insufficient occurrence data 

for making national estimates of disulfoton, diuron, and terbufos 

contamination. Occurrence data had been collected on those 

contaminants under UCMR1 but, as discussed earlier in this report, the 

sampling methodology used was not sufficient. EPA has not collected 

new occurrence data on the contaminants since then. As a result, the 

older data may not provide an accurate basis for EPA to use when 

making regulatory determinations.

The overall goal of SDWA is to ensure that public drinking water is safe. 

The UCMR program is an important component of EPA’s implementation 

of the act. As EPA’s primary data source for assessing the nation’s 

potential exposure to unregulated contaminants and the levels of that 

exposure, the UCMR plays a key role in EPA’s regulatory development 

process. As a result, the accuracy and timeliness of the data it provides 

are important to support informed decision making. The technical 

changes EPA has made to UCMR3 in response to our 2011 

recommendations are significant improvements over prior UCMR cycles. 

First, by more fully utilizing its statutory authority and monitoring for 30 

contaminants under UCMR3, EPA has increased the productivity of the 

UCMR program. As a result, more data will be available to inform 

regulatory determinations in the future. Second, by increasing the sample 

size of the public water systems monitoring under the screening survey 

approach, EPA has also increased the statistical strength of its monitoring 

results. The larger sample size should allow EPA to make better

estimates of exposure to drinking water contaminants. Third, by 

monitoring for contaminants at lower detection levels, or MRLs, the 

UCMR3 data are more likely to remain useful even in light of new 

information about the contaminants’ health effects in the future.

However, some statutory provisions pose limitations for obtaining 

additional and more timely data. First, because SDWA caps the number 

of UCMR contaminants in each 5-year cycle at 30, the agency is not able 

to take advantage of economies of scale by collecting occurrence data on 

additional contaminants. As a result, EPA does not have the opportunity 

to collect data on additional unregulated contaminants at little additional 

effort and cost to the agency or the public water systems. The cost to 

detect additional contaminants with analytical methods already being 

Conclusions
 

Page 45 GAO-14-103 Drinking Water

used by the UCMR program can be nominal. Second, the 2-year window 

SDWA initially established from the time EPA publishes the UCMR list to 

when it publishes the regulatory determinations does not provide 

adequate time for the UCMR data to support regulatory determinations in 

the same cycle. As a practical matter, the time frames SDWA initially 

established are not adequate to provide enough time for UCMR’s data 

collection period and EPA’s subsequent use of the data. As a result, 

regulatory determinations on given contaminants are typically delayed by 

a full 5-year cycle, meaning that about 10 years pass from when EPA 

identifies them on the CCL as potential problems and decides whether 

they need to be regulated. Two contaminants—methyl bromide and 1,1-

dichloroethane—will likely wait 22 years after their initial listing for 

regulatory determinations. Without congressional action to make the 

statutory time frames more realistic, the time lag and resultant delays are 

expected to continue in subsequent cycles.

The UCMR program faces other limitations that may cause EPA to base 

its regulatory determinations on inaccurate or outdated information. In 

particular, EPA’s standard monitoring frequency may not be accurately 

estimating the occurrence of certain contaminants in the public’s drinking 

water, particularly those that occur sporadically like viruses or seasonally 

like pesticides. By not varying the monitoring frequency for contaminants 

when appropriate, for example by increasing the frequency during the 

months when EPA expects viruses to be present, the UCMR data may 

not provide reliable estimates of contaminant occurrence. Similarly, by not 

remonitoring contaminants from prior UCMR cycles when appropriate, 

EPA may not have sufficient data to support its regulatory determinations.

EPA continues to use data from past UCMR cycles to inform its 

regulatory determinations, but those data sets have potential limitations. 

For example, EPA previously determined that some of the data collected 

under UCMR1 were not sufficient to make national estimates of 

contaminant occurrence. Because EPA has not remonitored those 

contaminants, the agency still does not have sufficient UCMR data about 

them. Similarly, some of the UCMR1 data may be outdated due to 

changing industrial and agricultural chemical use and environmental 

conditions. As a result, the existing UCMR data for certain contaminants 

may no longer accurately reflect current drinking water conditions. We are 

encouraged by recent statements from EPA officials indicating that they 

will consider whether adequate occurrence data for a contaminant had 

already been collected under a prior UCMR when selecting contaminants 

in the future. Finally, the timing of the UCMR program significantly 

reduces the availability of the data to support regulatory determinations. 

Specifically, the time lines for the contaminant selection process and 
 

Page 46 GAO-14-103 Drinking Water

monitoring period do not get the UCMR data into the hands of EPA 

officials in time to support regulatory determinations in the same cycle. 

The UCMR data are EPA’s preferred source of information on 

contaminant occurrence because the program has been specifically 

designed to yield nationally representative estimates of drinking water 

contamination. However, if the UCMR data are not available, EPA either 

must use data from another source, or delay making regulatory 

determinations on specific contaminants. For most of the UCMR3 

contaminants, over 10 years are likely to pass between the time that EPA 

first listed contaminants on CCL3 in 2009 and the time that regulatory 

determinations are made for those contaminants, expected in 2020. The 

SDWA deadlines, EPA’s lengthy contaminant selection process, and its 

3-year monitoring period all contribute to the time lag. As stated earlier, to 

change the statutory deadlines and adjust the time frames requires 

congressional action, and shortening the selection process and 

monitoring period requires EPA action. UCMR program officials 

coordinate closely with the other two EPA offices that make regulatory 

determinations and develop the CCL and are sensitive to the impact that 

timeliness has on each of these processes. We recognize that EPA 

officials must consider a variety of data quality objectives, logistical 

needs, and the burden on public water systems in managing the UCMR 

program, regulatory determinations, and CCL. But, since EPA officials 

consider the UCMR data to be their primary source of occurrence data for 

the regulatory determinations, it is important that these data also be 

timely. However, without a coordinated effort to address the time lag, 

most contaminants on the CCL will continue to wait 10 years or longer for 

a regulatory determination.

• To take advantage of opportunities to collect UCMR data on additional 

unregulated contaminants, Congress should consider amending 

SDWA to give EPA the flexibility to select more than 30 contaminants 

for monitoring under the UCMR program if high-priority contaminants, 

such as those on the CCL or contaminants of emerging concern, can 

be included at minimal cost, with minimal additional burden on public 

water systems, and while using analytical methods that EPA is 

already employing.

• To optimize the ability of the UCMR data to support regulatory 

determinations, Congress should consider adjusting the statutory time 

frames for the UCMR and regulatory determinations cycles so that 

EPA can use the UCMR data to support regulatory determinations in 

the same cycle.

Matters for 

Congressional 

Consideration
 

Page 47 GAO-14-103 Drinking Water

We recommend that the Administrator of the Environmental Protection 

Agency direct the Assistant Administrator of the Office of Water to take 

the following three actions:

• To help ensure that the UCMR data accurately reflect contaminant 

occurrence, vary the monitoring frequency for public water systems 

when the standard UCMR monitoring frequency is not expected to 

accurately detect the presence of contaminants, such as sporadically 

occurring viruses or pesticides that fluctuate seasonally.

• To help address potential limitations with the UCMR data, when 

considering if adequate data had been collected under a prior UCMR 

during the contaminant selection process, take into account whether: 

• the sampling methodology EPA used in a prior UCMR for a 

particular contaminant provided sufficient occurrence data to 

make a regulatory determination,

• the contaminant’s health information is in flux or has been updated 

and now indicates that adverse health effects occur at a lower 

level than that at which UCMR data were originally collected, or

• the data collected in an earlier cycle have become outdated and 

no longer present an accurate picture of contaminant occurrence, 

for example, because industrial or agricultural chemical use has 

changed.

• To optimize the ability of the UCMR program to support regulatory 

determinations, convene an internal working group of officials 

responsible for the UCMR, regulatory determinations, and CCL to fully 

examine opportunities to improve the timeliness of the UCMR 

program. Among other things, the working group should consider:

• whether a shorter process for selecting contaminants would yield 

a high-quality list, or whether the existing process can be started 

sooner, and

• whether monitoring for contaminants over a shorter period, 

instead of the current 3-year period, is feasible, given data quality, 

logistical needs, and the burden on public water systems.

We provided EPA with a draft of this report for its review and comment. In 

written comments, reproduced in appendix VI, EPA generally agreed with 

our findings and conclusions and is committed to implementing our 

recommendations when it develops the next UCMR. 

EPA also provided technical comments, which we incorporated as 

appropriate.

Recommendations for 

Executive Action

Agency Comments
 

Page 48 GAO-14-103 Drinking Water

As agreed with your offices, unless you publically announce the contents 

of this report earlier, we plan no further distribution until 30 days from the 

report date. At that time, we will send copies of this report to the 

Administrator of EPA and the appropriate congressional committees. In 

addition, this report will be available at no charge on the GAO website at 

http://www.gao.gov. 

If you or your staff members have any questions about this report, please 

contact me at (202) 512-3841or gomezj@gao.gov. Contact points for our 

Offices of Congressional Relations and Public Affairs may be found on 

the last page of this report. GAO staff who made key contributions to the 

report are listed in appendix VII.

J. Alfredo Gómez

Director, Natural Resources and Environment
Appendix I: Objectives, Scope, and 

Methodology

Page 49 GAO-14-103 Drinking Water

This report addressed the following objectives (1) evaluate the extent to 

which the Environmental Protection Agency (EPA) implemented the 

recommendations GAO made in 2011 to improve the Unregulated 

Contaminant Monitoring Rule (UCMR) program and any opportunities that 

may exist to strengthen it further; (2) identify the factors EPA considered 

when it selected the contaminants for monitoring under UCMR3 and the 

limitations, if any, that EPA faced in selecting the contaminants; and (3) 

examine the extent to which UCMR data support EPA’s regulatory 

determinations.

To obtain information for each of our objectives on issues related to 

monitoring unregulated drinking water contaminants, we surveyed a 

broad range of experts in two rounds using the Delphi method. The 

Delphi method consists of surveying experts in two or more rounds to 

obtain group agreement or consensus on key topics. For this report, the 

first round of the survey was comprised of open-ended questions that 

asked experts to provide their views on the strengths and weaknesses of 

EPA’s UCMR program, as well as suggestions for improving the program. 

The second round included primarily closed-ended questions developed 

from our content analysis of the first round survey responses. To identify 

experts for the first round of the survey, we reviewed public comments 

provided on EPA’s proposed rules for its Contaminant Candidate Lists 

(CCL), UCMR, and preliminary regulatory determinations. We also 

reviewed public nominations of drinking water contaminants submitted to 

EPA and EPA documentation on two expert panels it convened to provide 

input and review of chemical and microbial contaminants for CCL3. We 

identified 14 experts from academia, an analytical laboratory, 

environmental advocacy organizations, professional associations, water 

utilities, and federal and state government agencies. These experts were 

selected based on their demonstrated familiarity with EPA’s CCL, UCMR, 

and regulatory determination processes. The first round of the survey—

which ran from December 12, 2012 to January 4, 2013—asked these 

experts to respond to 10 open-ended questions. These questions asked 

about various aspects of the UCMR program that helped or hindered EPA 

in (1) selecting priority contaminants, (2) monitoring for selected 

contaminants, and (3) using the data to support regulatory 

determinations. We also asked the experts whether programmatic or 

statutory changes were needed to address any challenges identified. We 

received responses from 14 of the 14 experts we surveyed in the first 

round of the survey.

We performed a content analysis of the responses from the first round of 

the survey to identify the most important issues raised by the experts. We 

Appendix I: Objectives, Scope, and 

Methodology
Appendix I: Objectives, Scope, and 

Methodology

Page 50 GAO-14-103 Drinking Water

used the results of the content analysis to develop questions for the 

second round of the survey. Because this was not a sample survey, it had 

no sampling errors. However, the practical difficulties of conducting any 

survey can introduce nonsampling errors, such as difficulties interpreting 

a particular question, which can introduce unwanted variability into the 

survey results. We took steps to minimize nonsampling errors by 

pretesting the questionnaire with five experts. This helped ensure that the 

questions were clear and unbiased, and that the questionnaire did not 

place an undue burden on respondents. An independent reviewer within 

GAO also reviewed a draft of the questionnaire prior to its administration. 

We made appropriate revisions to the content and format of the second 

round survey questionnaire based on the pretests and independent 

review.

To identify experts for the second round of the survey, we developed a 

preliminary list of experts, which included the 14 experts who completed 

the first round of the survey and others identified through interviews with 

stakeholders and our review of public comments provided on EPA’s 

proposed rules. We contracted with the National Academy of Sciences to 

identify additional experts. We selected 48 experts for the second round 

of the survey based on their knowledge of one or more of the following 

topic areas: drinking water, contaminant monitoring, analytical methods, 

toxicology, risk assessment, and environmental regulation. Similar to the 

first round of the survey, the selected experts were from academia, 

analytical laboratories, environmental advocacy organizations, industry, 

water utilities, and federal and state government agencies. The second 

round of the survey was administered on the Internet from May 10, 2013 

to June 7, 2013. Experts were sent an e-mail invitation to complete the 

survey on a GAO web server using a unique username and password. To 

increase the response rate, we followed up with e-mails and personal 

phone calls to the experts to encourage participation in our survey. The 

second round of the survey had an 83 percent response rate. We 

received responses from 40 of 48 experts, including 12 who had also 

completed round one of the survey. The information that we obtained 

from the expert survey is not generalizable to all experts that have an 

interest in or knowledge of drinking water contaminant monitoring issues. 

The full survey and responses are available in appendix IV. The survey 

participants are listed in appendix V.

To evaluate the extent to which EPA implemented GAO’s May 2011 

recommendations to improve the UCMR program, we reviewed EPA’s 

proposed and final rules for the UCMR program and interviewed the 

relevant EPA officials who are responsible for designing and 
Appendix I: Objectives, Scope, and 

Methodology

Page 51 GAO-14-103 Drinking Water

implementing the UCMR program to identify specific actions the agency 

had taken. To identify any opportunities that may exist to strengthen the 

UCMR program further, we interviewed stakeholders to obtain their 

perspectives on the UCMR program and related issues. In addition, we 

assessed EPA’s sampling methodology against standard statistical 

criteria to determine whether the resulting sample sizes are likely to 

provide EPA with sufficient data for making national estimates of 

contaminant occurrence and exposure within an acceptable margin of 

error.

To identify the factors EPA considered when it selected the contaminants 

for monitoring under UCMR3, we reviewed EPA documentation 

describing the steps the agency took to select the contaminants, including 

UCMR3 working group meeting minutes and EPA’s proposed and final 

rules for the UCMR program and the CCL, which serves as EPA’s 

primary basis for selecting UCMR contaminants. We also interviewed 

EPA officials who are responsible for designing and implementing the 

UCMR program, including selecting the UCMR contaminants; as well as 

those responsible for developing the CCL and making regulatory 

determinations. To identify the limitations, if any, EPA faced in selecting 

the contaminants, we interviewed stakeholders to obtain their 

perspectives on the UCMR contaminant selection process and related 

issues. In addition, we assessed the UCMR contaminant selection 

process against statutory requirements.

To examine the extent to which UCMR data support EPA’s regulatory 

determinations, we reviewed EPA and Federal Register documents about 

the use of the data for making the CCL2 and CCL3 regulatory 

determinations. In addition, we interviewed EPA officials who are 

responsible for designing and implementing the UCMR program and for 

making regulatory determinations. We also considered the time frames 

for implementing the UCMR program and using UCMR data for making 

regulatory determinations and assessed them against statutory 

requirements and GAO criteria for program timeliness. There is broad 

recognition throughout the federal government that, in addition to being 

effective in producing desired outcomes and other important dimensions 

of performance, agencies need to operate programs and provide 

information about them in a timely and efficient manner. For example, the 

GPRA Modernization Act calls on agencies to set goals and measure 

their progress toward meeting them. Timeliness is an important 

dimension of program performance. In addition, EPA initiated a new 

drinking water strategy in 2010 that recognizes the need to improve the 

timeliness of its efforts to address unregulated contaminants.
Appendix I: Objectives, Scope, and 

Methodology

Page 52 GAO-14-103 Drinking Water

We conducted this performance audit from June 2012 to January 2014 in 

accordance with generally accepted government auditing standards. 

Those standards require that we plan and perform the audit to obtain 

sufficient, appropriate evidence to provide a reasonable basis for our 

findings and conclusions based on our audit objectives. We believe that 

the evidence obtained provides a reasonable basis for our findings and 

conclusions based on our audit objectives.
Appendix II: UCMR3 Contaminants

Page 53 GAO-14-103 Drinking Water

Assessment monitoring

1,4-dioxane

molybdenum

cobalt

1,2,3-trichloropropane

1,3-butadiene

chloromethane (methyl chloride)

1,1-dichloroethane

bromochloromethane (Halon 1011)

bromomethane (methyl bromide)

chlorodifluoromethane (HCFC-22)

vanadium

strontium

chromium 6 (hexavalent chromium)

total chromiuma

chlorate

perfluorooctanesulfonic acid

perfluorooctanoic acid

perfluoronanoic acid

perfluorohexanesulfonic acid

perfluoroheptanoic acid

perfluorobutanesulfonic acid

Screening survey

17-β-estradiol

17-α-ethynylestradiol (ethinyl estradiol)

estrone

4-androstrene-3,17-dione

estriol

equilin

testosterone

Pre-screen testing

enteroviruses noroviruses

Source: UCMR3 final rule.

a

Total chromium is a regulated contaminant. EPA used a different statutory authority, section 

1445(a)(1)(A) of the Safe Water Drinking Act, to require monitoring for total chromium.

Appendix II: UCMR3 Contaminants
Appendix III: Information on Analytical 

Methods

Page 54 GAO-14-103 Drinking Water

Analytical methods are laboratory tests that measure the level of chemical 

and microbial contamination in a sample of drinking water. Analytical 

methods specify the volume of the sample to be tested, laboratory 

equipment and procedure used to test the sample, and quality control 

procedures to ensure the test is run correctly. Analytical methods vary 

based on the type of contaminant; different equipment and techniques are 

required for analyzing chemicals versus microbes. For example, 

laboratories use specialized scientific equipment such as gas 

chromatograph-mass spectrometers (GC-MS) to detect the presence of 

some chemicals in drinking water.

Because the Unregulated Contaminant Monitoring Rule (UCMR) collects 

nationwide data, the Environmental Protection Agency’s (EPA) goal is to 

use analytical methods that offer consistent application across the 

country. To get the data quality and accuracy that EPA needs, the agency 

uses analytical methods for UCMR that, among other requirements (1) 

have sufficient “holding times” for shipment of water samples from water 

utilities to laboratories; (2) can be used by a variety of laboratories with 

varying levels of expertise; and (3) can be used equally effectively under 

different drinking water conditions and types.1 EPA often develops 

analytical methods for the UCMR program that meet these specific 

requirements. When EPA develops an analytical method, there are many 

key steps it follows. EPA begins with optimizing instrumentation and 

determining the best calibration, which involves setting up the equipment 

to measure a contaminant at the desired level. Next, EPA staff optimize 

the solid phase extraction—a process that involves separating 

compounds that are dissolved or suspended in water from other 

compounds in the water sample according to their physical and chemical 

properties in order to isolate the contaminant for analysis. Then, EPA staff 

determine which preservatives to use that will allow the chemical to be 

preserved in the water sample. They also determine any interferences– if 

there are other chemicals or substances in the water sample that may 

have similar physical and chemical properties and thus interfere with the 

chemical to be analyzed—and how to address such interferences, if any.

Then, EPA staff determine the holding times for the contaminant and the 

water sample; as noted earlier, EPA must have sufficient “holding times” 

for shipment of water samples from water utilities to laboratories. These 

 

1

Drinking water types in the United States include groundwater sources, such as 

underground aquifers, and surface water sources, such as streams, rivers, and lakes. 

Appendix III: Information on Analytical 

Methods
Appendix III: Information on Analytical 

Methods

Page 55 GAO-14-103 Drinking Water

holding times must not have any negative impact in quality on the 

contaminant to be analyzed in the water sample. After following all these 

steps, if the analytical method meets EPA’s data quality objectives, then 

EPA writes the method so that laboratories across the country can use 

and follow the EPA instructions to measure the level of contamination in 

drinking water. EPA then sends the written analytical method to several 

laboratories to ensure the method works as written; this process is known 

as a multilab verification process. If the method passes this verification 

process, then EPA publishes and uses the analytical method in a future 

UCMR. On the other hand, if the analytical method does not meet the 

data quality objectives that EPA has set, EPA revises the technical 

approach in order for the earlier steps in the analysis to lead to a method 

that meets the data quality objectives. See figure 6.
Appendix III: Information on Analytical 

Methods

Page 56 GAO-14-103 Drinking Water

Figure 6: EPA’s Process for Analytical Method Development

Developing an analytical method can be a complex, technically 

challenging, and time-consuming process. For example, EPA officials 

cited challenges for developing methods for some CCL3 contaminants 

such as the high water solubility of some contaminants, as well as some 
Appendix III: Information on Analytical 

Methods

Page 57 GAO-14-103 Drinking Water

contaminants’ instability in water. In such cases, EPA cannot keep these 

contaminants stable in the water samples for the minimum holding times 

that are required between the collection of samples by public water 

systems and sending the samples to the laboratories for analysis. For 

these contaminants, EPA is still working on techniques that will allow the 

agency to develop an analytical method that works effectively under all 

the conditions noted above that UCMR analytical methods must meet.

EPA officials said it can take 1 to 2 years to develop a standard method 

that meets their data quality requirements and 2 to 3 years for more 

complex methods.

Most often, the UCMR program uses EPA analytical methods, but it also 

allowed some methods developed by others as alternatives for UCMR3.

EPA is also using compliance methods in the UCMR3 program. 

Compliance methods are analytical methods that laboratories are 

required to use when monitoring for regulated drinking water 

contaminants. For example, the analytical method for volatile organic 

compounds that EPA is using for UCMR3 is a compliance method.2 In 

addition, EPA involves stakeholders in its development of analytical 

methods. In May 2013, EPA held a public meeting and webinar to provide 

stakeholders with an update on analytical methods completed or under 

development for potential use in the UCMR program. Several external 

stakeholders participated in the meeting, both in person and via webinar. 

Some of them provided suggestions to address challenges EPA was 

facing with certain methods.

 

2

Volatile organic compounds, or VOCs, may occur naturally in the environment or occur 

only as a result of manmade activities; some VOCs have both origins. VOC contamination 

of drinking water supplies is a human-health concern because many are toxic and are 

known or suspected human carcinogens. EPA has issued drinking water regulations for 

eight VOCs. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 58 GAO-14-103 Drinking Water

The questions we asked experts in Round 2 of our survey are shown 

below. Our survey was composed of closed- and open-ended questions. 

In this appendix, we include all the survey questions and aggregate 

results of responses to the closed-ended questions; we do not provide 

information on responses provided to the open-ended questions. For a 

more detailed discussion of our survey methodology, see appendix I. For 

a list of the experts who completed our survey, see appendix V.

Appendix IV: Round 2 Survey Questionnaire 

and Results
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 59 GAO-14-103 Drinking Water

Survey on EPA's Unregulated Contaminant Monitoring Program 

U.S. Government Accountability Office

EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect data for some 

contaminants that are suspected to be present in drinking water, but do not have health-based standards set 

under the Safe Drinking Water Act. Under the Safe Drinking Water Act, EPA is responsible for identifying and 

regulating drinking water contaminants that may pose a public health risk. Specifically, the act directs EPA to: 

1. Publish a list every 5 years of contaminants that are a) not currently regulated b) known or anticipated to 

occur in public water systems and c) may require regulation. EPA has implemented this provision as the 

Contaminant Candidate List. 

2. Establish a program to monitor unregulated contaminants and publish a list every 5 years of up to 30 

contaminants to be monitored by public water systems. EPA has implemented this provision as the 

Unregulated Contaminant Monitoring Rule (UCMR) program. 

3. Determine whether or not to regulate at least 5 contaminants included on the list of unregulated 

contaminants every 5 years. EPA has implemented this provision as the regulatory determination process. The 

act specifies that EPA shall regulate a drinking water contaminant under certain conditions. To see these 

conditions, click here. [In the online-version of the survey, this was a live link to the Safe Drinking Water Act 

requirements for making a regulatory determination.]

Some of the contaminants on the Contaminant Candidate List are monitored under the UCMR. EPA uses the 

monitoring data, along with information about the contaminants' health effects, to determine whether or not to 

regulate the contaminants. EPA is currently in its third round of the UCMR program (UCMR-3). 

EPA is monitoring 30 contaminants under UCMR-3. Click here to review the list. [In the online-version of the 

survey this was a live link. See appendix II of this report for a list of the 30 contaminants.] 

--------------------------------------------------------------------------------

Section 1: UCMR Program Requirements and Considerations

The Safe Drinking Water Act requires that EPA publish a list of unregulated contaminants that pose the 

greatest public health concern, are known or anticipated to occur in public water systems, and may require 

regulation. This is known as the Contaminant Candidate List (CCL). 

 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 60 GAO-14-103 Drinking Water

1. EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect monitoring data for 

informing its regulatory determinations about some of the contaminants on the CCL. The Safe Drinking Water 

Act requires EPA to select contaminants that pose the greatest public health concern for its CCL and for 

regulatory determinations. 

When selecting contaminants for monitoring under the UCMR, should EPA select contaminants that potentially 

pose the greatest public health concern? 

Q1 Frequency

Cumulative

Frequency

1-Definitely yes 24 24

2-Probably yes 13 37

3-Probably no 1 38

5-Not enough information to judge 2 40

2. EPA identified the contaminants for its third UCMR list (UCMR-3) largely from contaminants identified in its 

third Contaminant Candidate List (CCL-3). To create CCL-3, EPA identified about 7,500 contaminants and 

then analyzed the contaminants' potential to occur in public water systems and to be a public health concern. 

Based on those criteria, EPA selected 116 contaminants for CCL-3 which it determined pose the greatest 

public health concern. 

Was CCL-3 a reasonable source for EPA to use when it began identifying contaminants for the UCMR-3? 

Q2 Frequency

Cumulative

Frequency

1-Definitely yes 17 17

2-Probably yes 20 37

3-Probably no 2 39

5-Not enough information to judge 1 40

 Please explain your answer to question 2: 

 [Open ended]
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 61 GAO-14-103 Drinking Water

3. The UCMR and CCL are created through separate processes. EPA finalized CCL-3 in 2009, and finalized 

UCMR-3 in 2012. UCMR-3 includes 22 contaminants from CCL-3 and 8 other contaminants. 

If EPA combined the CCL and UCMR contaminant selection processes, would the resulting UCMR list likely be 

of similar or better quality when compared to the UCMR list created under the current separate processes? 

Q3 Frequency

Cumulative

Frequency

1-Definitely yes 5 5 

2-Probably yes 15 20

3-Probably no 10 30

5-Not enough information to judge 10 40

Please explain your answer to question 3: 

[Open ended] 

4. The Safe Drinking Water Act requires EPA to issue a new list of contaminants for monitoring under the 

UCMR every 5 years. Is 5 years enough time to select contaminants and implement a new round of the UCMR 

program? 

Q4 Frequency

Cumulative

Frequency

1-Definitely yes 10 10

2-Probably yes 18 28

3-Probably no 10 38

4-Definitely no 2 40

5. For UCMR-3, EPA selected 8 contaminants that were not on CCL-3. Some of these 8 contaminants 

became priorities between the publication of the CCL-3 and UCMR-3 lists. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 62 GAO-14-103 Drinking Water

Is it worthwhile for EPA to select contaminants for the UCMR when they are not on the CCL? 

Q5 Frequency

Cumulative

Frequency

1-Definitely yes 20 20

2-Probably yes 13 33

3-Probably no 7 40

6. The UCMR list of contaminants is based largely on the CCL, and UCMR supports regulatory 

determinations. 

Do the 30 contaminants EPA selected warrant being included in UCMR-3? Click here to review the list. [In the 

online-version of the survey this was a live link. See appendix II of this report for a list of the 30 contaminants.] 

Q6 Frequency

Cumulative

Frequency

1-Definitely yes 11 11

2-Probably yes 19 30

3-Probably no 3 33

4-Definitely no 3 36

5-Not enough information to judge 1 37

6-No answer 3 40

7. EPA added chromium-6 and total chromium to the UCMR-3 list based largely on the strength of public 

comments supporting these additions. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 63 GAO-14-103 Drinking Water

7A. Did chromium-6 warrant being included on the UCMR-3 list? 

Q7A Frequency

Cumulative

Frequency

1-Definitely yes 19 19

2-Probably yes 16 35

3-Probably no 3 38

5-Not enough information to judge 2 40

7B. Did total chromium warrant being included on the UCMR-3 list? 

Q7B Frequency

Cumulative

Frequency

1-Definitely yes 11 11

2-Probably yes 17 28

3-Probably no 8 36

5-Not enough information to judge 4 40

--------------------------------------------------------------------------------

Section 2: Factors EPA Considers when Selecting Contaminants for UCMR

8. One factor EPA considers when selecting contaminants for UCMR is what health effects information is 

available for the universe of unregulated contaminants. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 64 GAO-14-103 Drinking Water

In general, was enough health effects information available when EPA began selecting contaminants in 2009 

to identify contaminants that potentially pose the greatest public health concern? 

Q8 Frequency

Cumulative

Frequency

1-Definitely yes 2 2 

2-Probably yes 14 16

3-Probably no 15 31

4-Definitely no 2 33

5-Not enough information to judge 4 37

6-No answer 3 40

9. EPA also needs health effects information when determining whether or not to regulate a contaminant 

monitored under UCMR. However, health effects information is often being developed for contaminants at the 

same time that the UCMR program is collecting data about contaminant occurrence. 

Given this situation, is it worthwhile for EPA to select contaminants for UCMR when the health effects 

information needed to make regulatory determinations is not yet available? 

Q9 Frequency

Cumulative

Frequency

1-Definitely yes 8 8 

2-Probably yes 21 29

3-Probably no 8 37

4-Definitely no 2 39

6-No answer 3 40

10. Another factor EPA considers when selecting contaminants for UCMR is whether or not the contaminant 

was included in a prior round of UCMR. EPA typically does not select contaminants that were previously 

included. While this policy reduces the burden on public water systems, there have been situations in which 

monitoring again could enable EPA to collect better data. The following questions ask about such situations. 

 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 65 GAO-14-103 Drinking Water

10A. In the first round of the UCMR program, the sampling methodology that EPA used to select water 

systems had limitations, and therefore the program did not provide sufficient data for making decisions about 

whether or not to regulate some of the contaminants. 

Given the tradeoff between burden on water systems and data quality, would it be worthwhile for EPA to 

consider selecting some of those contaminants again for monitoring under UCMR? 

Q10A Frequency

Cumulative

Frequency

1-Definitely yes 15 15

2-Probably yes 16 31

3-Probably no 7 38

4-Definitely no 1 39

5-Not enough information to judge 1 40

 

10B. In prior rounds of the UCMR program, some of the analytical methods used were not sensitive enough to 

detect contaminants at EPA's health effects benchmark. More sensitive analytical methods have since become 

available for some of these contaminants. 

Given the tradeoff between burden on water systems and data quality, would it be worthwhile for EPA to 

consider selecting some of those contaminants again for monitoring under UCMR? 

Q10B Frequency

Cumulative

Frequency

1-Definitely yes 18 18

2-Probably yes 16 34

3-Probably no 3 37

5-Not enough information to judge 3 40

 

10C. New or updated health effects information is now available for some contaminants monitored in prior 

rounds of the UCMR. The new information indicates that health effects occur at lower concentrations than 

those previously monitored for. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 66 GAO-14-103 Drinking Water

Given the tradeoff between burden on water systems and data quality, would it be worthwhile for EPA to 

consider selecting some of those contaminants again for monitoring under UCMR? 

Q10C Frequency

Cumulative

Frequency

1-Definitely yes 19 19

2-Probably yes 13 32

3-Probably no 4 36

5-Not enough information to judge 4 40

 

11. Another factor EPA considers when selecting contaminants for UCMR is whether analytical methods will 

be available to detect these contaminants in drinking water. EPA typically develops analytical methods for the 

contaminants it plans to monitor. For UCMR-3, EPA also considered analytical methods that had been 

developed by Standard Methods and the American Society for Testing and Materials. 

For future rounds of UCMR, will it be worthwhile for EPA to reach out to organizations that develop such 

analytical methods before it selects contaminants? 

Q11 Frequency

Cumulative

Frequency

1-Definitely yes 32 32

2-Probably yes 8 40

 

12. Another factor EPA considers when selecting contaminants for UCMR is whether the contaminants are 

similar to others it will be monitoring. EPA selected 6 contaminants for UCMR-3 primarily because they could 

be detected by an analytical method that will be used for another UCMR-3 contaminant. These 6 were not on 

the CCL-3, EPA's primary source for selecting UCMR-3 contaminants. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 67 GAO-14-103 Drinking Water

Is it worthwhile for EPA to select contaminants for the UCMR primarily because they can be detected by an 

analytical method that will be used for another UCMR contaminant? 

Q12 Frequency

Cumulative

Frequency

1-Definitely yes 10 10

2-Probably yes 17 27

3-Probably no 12 39

4-Definitely no 1 40

 

13. Another factor EPA considers when selecting contaminants is stakeholder input. For UCMR-3, EPA 

convened a State working group, held a public stakeholder meeting, and collected public comments on the 

proposed rule published in the Federal Register. 

Did these means of communication give stakeholders enough opportunity to provide input on the contaminants 

that EPA selected for UCMR-3? 

Q13 Frequency

Cumulative

Frequency

1-Definitely yes 10 10

2-Probably yes 23 33

3-Probably no 5 38

4-Definitely no 1 39

5-Not enough information to judge 1 40

 

14. When EPA develops the CCL it is reviewed by EPA's Science Advisory Board. In addition, EPA solicited 

additional expert input from the National Drinking Water Advisory Board and from other outside experts when it 

selected contaminants for the CCL-3. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 68 GAO-14-103 Drinking Water

Should EPA use similar means to obtain additional expert input when it selects contaminants for the UCMR? 

Q14 Frequency

Cumulative

Frequency

1-Definitely yes 24 24

2-Probably yes 15 39

3-Probably no 1 40

 

15. In addition to EPA, the US Geological Survey, some states, and other groups generate contaminant 

occurrence data. EPA reviews some of this other data when selecting the UCMR contaminants. 

Is it worthwhile for EPA to consider this other data on contaminant occurrence when it selects contaminants for 

UCMR? 

Q15 Frequency

Cumulative

Frequency

1-Definitely yes 32 32

2-Probably yes 7 39

3-Probably no 1 40

--------------------------------------------------------------------------------

Section 3: Collection of Contaminant Occurrence Data through the UCMR Program

16. EPA varies the frequency for monitoring based primarily on the source water type. Under UCMR-3, 

surface water systems must monitor for 4 consecutive quarters with sampling events 3 months apart. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 69 GAO-14-103 Drinking Water

Is the requirement that surface water systems monitor for 4 consecutive quarters likely to provide EPA 

sufficient data to determine whether contaminants occur with a frequency and at levels of public health 

concern? 

Q16 Frequency

Cumulative

Frequency

1-Definitely yes 1 1 

2-Probably yes 26 27

3-Probably no 7 34

4-Definitely no 5 39

5-Not enough information to judge 1 40

 

Please explain your answer to question 16: 

[Open ended] 

17. Under UCMR-3, ground water systems must monitor twice in a 12-month period with sampling events 5-

7 months apart. 

Is the requirement that ground water systems monitor twice in a 12-month period likely to provide EPA 

sufficient data to determine whether contaminants occur with a frequency and at levels of public health 

concern? 

Q17 Frequency

Cumulative

Frequency

1-Definitely yes 3 3

2-Probably yes 25 28

3-Probably no 10 38

4-Definitely no 2 40

 

Please explain your answer to question 17: 

[Open ended] 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 70 GAO-14-103 Drinking Water

18. Under UCMR-3, non-disinfecting ground water systems located in sensitive hydrogeological areas (i.e., 

karst or fractured bedrock) must monitor twice in a 12-month period with sampling events 5-7 months apart for 

2 viruses. 

Is the requirement that these non-disinfecting ground water systems monitor twice in a 12-month period 

likely to provide EPA sufficient data to determine whether the contaminants occur with a frequency and at 

levels of public health concern? 

Q18 Frequency

Cumulative 

Frequency

2-Probably yes 9 9 

3-Probably no 16 25

4-Definitely no 7 32

5-Not enough information to judge 4 36

6-No answer 4 40

Please explain your answer to question 18: 

[Open ended] 

19. UCMR-3 is a national study with samples taken over 3 years (January 2013 through December 2015) and 

across all months and seasons to capture seasonal fluctuations in contaminant occurrence. 

19A. For the 30 contaminants being monitored under UCMR-3, is this 3-year monitoring timeframe likely to 

provide EPA sufficient information on seasonal fluctuations in contaminant occurrence? Click here to review 

the list of 30 contaminants. [In the online-version of the survey this was a live link. See appendix II of this report 

for a list of the 30 contaminants.] 

Q19A Frequency

Cumulative

Frequency

1-Definitely yes 5 5 

2-Probably yes 27 32

3-Probably no 4 36

4-Definitely no 1 37

5-Not enough information to judge 3 40
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 71 GAO-14-103 Drinking Water

19B. For the 30 contaminants being monitored under UCMR-3, would a 2-year monitoring timeframe instead 

of the 3-year timeframe be likely to provide EPA sufficient information on seasonal fluctuations in contaminant 

occurrence? 

Q19B Frequency

Cumulative

Frequency

1-Definitely yes 3 3 

2-Probably yes 16 19

3-Probably no 9 28

4-Definitely no 2 30

5-Not enough information to judge 9 39

6 – No answer 10 40

 

20. EPA established a three-tiered strategy for monitoring UCMR contaminants based primarily on the 

availability of analytical methods. UCMR's Tier I monitoring requires all water systems serving more than 

10,000 people and a random sample of 800 water systems serving 10,000 or fewer people to monitor those 

contaminants that can be detected by analytical methods that are widely used in drinking water laboratories. 

Is Tier I monitoring likely to provide EPA sufficient data to determine whether contaminants occur with a 

frequency and at levels of public health concern? 

Q20 Frequency

Cumulative

Frequency

1-Definitely yes 4 4 

2-Probably yes 27 31

3-Probably no 3 34

5-Not enough information to judge 4 38

6-No answer 2 40

 

21. UCMR's Tier II monitoring requires all water systems serving more than 100,000 people, 320 randomly 

selected water systems serving 10,001 to 100,000 people, and 480 randomly selected water systems serving 

10,000 or fewer people to monitor those contaminants that can be detected by newly developed analytical 

methods that are used in fewer drinking water laboratories. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 72 GAO-14-103 Drinking Water

Is Tier II monitoring likely to provide EPA sufficient data to determine whether contaminants occur with a 

frequency and at levels of public health concern? 

Q21 Frequency

Cumulative

Frequency

1-Definitely yes 1 1 

2-Probably yes 25 26

3-Probably no 8 34

5-Not enough information to judge 4 38

6-No answer 2 40

 

22. UCMR's Tier III monitoring requires a random sample of 800 non-disinfecting ground water systems 

located in sensitive hydrogeological areas (i.e., karst or fractured bedrock) to monitor those contaminants that 

can be detected by very new or specialized analytical methods that are used in a small set of drinking water 

laboratories. 

Is Tier III monitoring likely to provide EPA sufficient data to determine whether contaminants occur with a 

frequency and at levels of public health concern? 

Q22 Frequency

Cumulative

Frequency

1-Definitely yes 1 1 

2-Probably yes 17 18

3-Probably no 11 29

4-Definitely no 2 31

5-Not enough information to judge 8 39

6-No answer 1 40
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 73 GAO-14-103 Drinking Water

23. Overall, is the three-tiered monitoring strategy described in questions 20-22, which varies the number and 

size of water systems based on the availability of analytical methods, likely to provide EPA sufficient data to 

determine whether contaminants occur with a frequency and at levels of public health concern? 

Q23 Frequency Cumulative 

Frequency

2-Probably yes 26 26

3-Probably no 5 31

4-Definitely no 1 32

5-Not enough information to judge 6 38

6-No answer 2 40

 

Please explain your answer to question 23: 

[Open ended] 

 

24. Under UCMR-3, systems must monitor for 5 pathogen indicators. This monitoring will be conducted in 

conjunction with virus monitoring of enterovirus and norovirus. 

The pathogen indicators are: Total coliforms, E. coli, Enterococci, Bacteriophage, and Aerobic spores. 

Is this type of monitoring likely to help EPA better understand the co-occurrence of pathogen indicators and 

viruses? 

Q24 Frequency

Cumulative

Frequency

1-Definitely yes 9 9 

2-Probably yes 21 30

3-Probably no 3 33

4-Definitely no 1 34

5-Not enough information to judge 3 37

6-No answer 3 40

 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 74 GAO-14-103 Drinking Water

25. Under UCMR-3, systems must monitor for total chromium in conjunction with chromium-6. 

25A. Is this type of monitoring likely to provide EPA with valuable information on the co-occurrence of total 

chromium and chromium-6? 

Q25A Frequency

Cumulative

Frequency

1-Definitely yes 14 14

2-Probably yes 20 34

3-Probably no 2 36

5-Not enough information to judge 3 39

6-No answer 1 40

 

25B. Is this type of monitoring likely to provide EPA with valuable information on the usefulness of monitoring 

for total chromium as an indicator for chromium-6? 

 

Q25B Frequency

Cumulative

Frequency

1-Definitely yes 7 7 

2-Probably yes 19 26

3-Probably no 8 34

4-Definitely no 2 36

5-Not enough information to judge 3 39

6-No answer 1 40

--------------------------------------------------------------------------------

Section 4: Use of the UCMR Contaminant Occurrence Data 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 75 GAO-14-103 Drinking Water

26. EPA uses UCMR data to make regulatory determinations for some of the contaminants listed on the CCL. 

Due to a time lag, the UCMR-3 occurrence data will not be available to inform the regulatory determinations 

about the contaminants on CCL-3. As a result, EPA is using occurrence data from prior UCMRs to inform 

these regulatory determinations. CCL-3 includes 28 contaminants monitored under prior UCMRs. 

Is this likely to be an effective strategy for making regulatory determinations, given the time lag? 

Q26 Frequency Cumulative 

Frequency

1-Definitely yes 1 1 

2-Probably yes 9 10

3-Probably no 18 28

4-Definitely no 7 35

5-Not enough information to judge 4 39

6-No answer 1 40

Please explain your answer to question 26: 

[Open ended] 

27. Sometimes EPA waits several years before it uses the UCMR occurrence data to inform its regulatory 

determinations. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 76 GAO-14-103 Drinking Water

After the UCMR occurrence data has been collected, about how long is it likely to be a reliable indicator of the 

frequency and level of drinking water contamination? 

Q27 Frequency

Cumulative

Frequency

b.-Less than 5 years 11 11

c.-5 to less than 11 years 8 19

d.-11 to less than 16 years 2 21

e.-16 to less than 20 years 1 22

g.-Not enough information to judge 18 40

28. The primary purpose of the UCMR program is to collect contaminant occurrence data for informing 

regulatory determinations which are based, in part, on the frequency and level of drinking water contamination. 

Overall, how effective has the UCMR program been at collecting sufficient data to determine whether 

contaminants occur with a frequency and at levels of public health concern? 

Q28 Frequency

Cumulative

Frequency

1-Very effective 9 9 

2-Somewhat effective 26 35

3-Not effective 1 36

4-Not enough information to judge 3 39

5-No answer 1 40

 

29. Another purpose of the UCMR program is to inform EPA's development of future CCLs. EPA expects to 

complete its data collection and analysis for UCMR-3 in 2016; it expects to finalize its next CCL in 2014. 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 77 GAO-14-103 Drinking Water

Given the tradeoff between data completeness and timeliness, would it be worthwhile for EPA to use partial 

UCMR data to inform its next CCL? 

Q29 Frequency

Cumulative

Frequency

1-Definitely yes 11 11

2-Probably yes 24 35

3-Probably no 5 40

 

30. An additional purpose of the UCMR program is to inform EPA's health research planning. For example, 

EPA might prioritize the completion of health effects information for a specific contaminant over others if it 

believes the contaminant is likely to be found in drinking water. EPA expects to complete its data collection and 

analysis for UCMR-3 in 2016; its health research planning is on-going. 

Given the tradeoff between data completeness and timeliness, would it be worthwhile for EPA to use partial 

UCMR data to inform its health research planning? 

Q30 Frequency

Cumulative

Frequency

1-Definitely yes 16 16

2-Probably yes 20 36

3-Probably no 2 38

5-Not enough information to judge 2 40

 

IMPORTANT: Please continue to the next screen to submit your final responses to GAO. 

--------------------------------------------------------------------------------

Submit Your Final Responses to GAO

31. Are you ready to submit your final completed survey to GAO? 
Appendix IV: Round 2 Survey Questionnaire 

and Results

Page 78 GAO-14-103 Drinking Water

(This is equivalent to mailing a completed paper survey to us. It tells us that your answers are official and final.)

Yes, my survey is complete - To submit your final responses, please click on "Exit" 

below

No, my survey is not yet complete - To save your responses for later, please click on 

"Exit" below
Appendix V: List of Experts Who Completed 

the Surveys

Page 79 GAO-14-103 Drinking Water

Scott Biernat, Association of Metropolitan Water Agencies

Melissa Billman, Fairfax Water Utility

Danielle Blacet, Association of California Water Agencies

Mark Borchardt, Ph.D., U.S. Department of Agriculture

Bryan Brooks, Ph.D., Baylor University

Gary Burlingame, Philadelphia Water Department

Peter L. deFur, Ph.D., Environmental Stewardship Concepts

Gregory Delzer, U.S. Geological Survey

Andy Eaton, Ph.D., Eurofins Eaton Analytical, Inc.

Stephen Estes-Smargiassi, Massachusetts Water Resources Authority

Mike Focazio, Ph.D., U.S. Geological Survey

David Fischer, American Chemistry Council

Ann Marie Gebhart, Ph.D., ToxServices LLC

Will Gonzalez, Coachella Valley Water District

Annette Guiseppi-Elie, Ph.D., DuPont

George Hallberg, Ph.D., The Cadmus Group, Inc.

Charles Hertz, Ph.D.,Aqua America, Inc.

Michael Hutcheson, Ph.D., Massachusetts Department of

 Environmental Protection

Elston Johnson, Texas Commission on Environmental Quality

Todd Johnson, Minnesota Department of Health

Nancy Kim, Ph.D., State University of New York at Albany

Rebecca D. Klaper, Ph.D., University of Wisconsin-Milwaukee

Dana Kolpin, U.S. Geological Survey

John H. Koon, Ph.D., Georgia Technical Institute

Mark LeChevallier, Ph.D., American Water

Gary R. Lynch, Park Water Company

Charles Maddox, Austin Water Utility

David Mazzera, Ph.D., California Department of Public Health

Erik Olson, Pew Charitable Trusts

Darrell Osterhoudt, Association of State Drinking Water Administrators

Rebecca Parkin, Ph.D., George Washington University

Gloria Post, Ph.D., New Jersey Department of Environmental Protection

Alan Roberson, American Water Works Association

Renee Sharp, Environmental Working Group

Mary Skopec, Ph.D., Iowa Department of Natural Resources

Shane Snyder, Ph.D., University of Arizona

Mark D. Sobsey, Ph.D., University of North Carolina at Chapel Hill

Lynn Thorp, Clean Water Action

Patricia Toccalino, Ph.D., U.S. Geological Survey

Lloyd Wilson, Ph.D., New York State Department of Health

Mae Wu, Natural Resources Defense Council

Nira Yamachika, Orange County Water District

Appendix V: List of Experts Who Completed 

the Surveys
Appendix VI: Comments from the 

Environmental Protection Agency

Page 80 GAO-14-103 Drinking Water

Appendix VI: Comments from the 

Environmental Protection Agency
Appendix VI: Comments from the 

Environmental Protection Agency

Page 81 GAO-14-103 Drinking Water
Appendix VI: Comments from the 

Environmental Protection Agency

Page 82 GAO-14-103 Drinking Water
Appendix VII: GAO Contact and Staff 

Acknowledgments

Page 83 GAO-14-103 Drinking Water

J. Alfredo Gómez, (202) 512-3841 or gomezj@gao.gov

In addition to the individual named above, Diane B. Raynes (Assistant 

Director), Elizabeth Beardsley, Mark Braza, Justin Fisher, Annamarie 

Lopata, Rebecca Makar, Christopher Murray, Alison O’Neill, Dan Royer, 

Kelly Rubin, and Esther Toledo made significant contributions to this 

report.

Appendix VII: GAO Contact and Staff 

Acknowledgments

GAO Contact

Staff 

Acknowledgments
Related GAO Products

Page 84 GAO-14-103 Drinking Water

Chemical Assessments: An Agencywide Strategy May Help EPA Address 

Unmet Needs for Integrated Risk Information System Assessments.

GAO-13-369. Washington, D.C.: May 10, 2013.

Environmental Health: Action Needed to Sustain Agencies’ Collaboration 

on Pharmaceuticals in Drinking Water. GAO-11-346. Washington, D.C.: 

August 8, 2011.

Safe Drinking Water Act: Improvements in Implementation Are Needed to 

Better Assure the Public of Safe Drinking Water. GAO-11-803T. 

Washington, D.C.: July 12, 2011.

Safe Drinking Water Act: EPA Should Improve Implementation of 

Requirements on Whether to Regulate Additional Contaminants.

GAO-11-254. Washington, D.C.: May, 27, 2011.

Perchlorate: Occurrence is Widespread but at Varying Levels; Federal 

Agencies Have Taken Some Actions to Respond to and Lessen 

Releases. GAO-10-769. Washington, D.C.: August 12, 2010.

Safe Drinking Water Act: Progress and Future Challenges in 

Implementing the 1996 Amendments. GAO/RCED-99-31. Washington, 

D.C.: January 14, 1999.

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