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Drinking Water: EPA Has Improved Its Unregulated Contaminant Monitoring Program, but Additional Action Is Needed

GAO-14-103 Published: Jan 09, 2014. Publicly Released: Feb 10, 2014.
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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.

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.


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.

Matter for Congressional Consideration

Matter Status Comments
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 Contaminant Candidate List (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.
Closed – Not Implemented
Since we issued this report, and confirmed as of July 2021, Congress has not taken action to address this matter and we are closing it as not implemented.
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.
Closed – Not Implemented
Since we issued this report, and confirmed as of July 2021, Congress has not taken action to address this matter and we are closing it as not implemented.

Recommendations for Executive Action

Agency Affected Recommendation Status
Environmental Protection Agency The Administrator of the Environmental Protection Agency should direct the Assistant Administrator of the Office of Water 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.
Closed – Implemented
In December 2016, EPA published the Final Rule for the UCMR4 program in the Federal Register, and specified that public water systems are to monitor for 10 cyanotoxins during a four-consecutive month period from March 2018 through November 2020, (excluding December, January and February). The varied monitoring for the cyantoxins was designed to better reflect the times of year when these contaminants are more likely to occur in drinking water, according to EPA. Public water systems will monitor for 20 additional contaminants during a 12-month period from January 2018 through December 2020. These cyanotoxins represent one third of the total list of the UCMR4 contaminants, and EPA is requiring increased sampling frequency and narrower monitoring timeframes for them. Sampling will take place twice a month for four consecutive months (total of eight sampling events) for water systems.
Environmental Protection Agency The Administrator of the Environmental Protection Agency should direct the Assistant Administrator of the Office of Water 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: (1) the sampling methodology EPA used in a prior UCMR for a particular contaminant provided sufficient occurrence data to make a regulatory determination, (2) 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 (3) 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.
Closed – Implemented
In July and August 2016, EPA provided GAO with information about the agency's processes for UCMR4, as published in the Federal Register, such as how the agency considered the latest health information for contaminants monitored in prior UCMR cycles, and the process for vetting UCMR candidate contaminants, including identifying Contaminant Candidate List (CCL) contaminants that were not monitored during more recent UCMRs. In addition, EPA indicated that during the UCMR4 prioritization process, the health effects information was updated for all contaminants using the best available data from the most recent Regulatory Determination, CCL, and other publically available EPA sources that may have been published in the interim.
Environmental Protection Agency The Administrator of the Environmental Protection Agency should direct the Assistant Administrator of the Office of Water 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: (1) whether a shorter process for selecting contaminants would yield a high-quality list, or whether the existing process can be started sooner, and (2) 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.
Closed – Implemented
In July and August 2016, EPA officials provided GAO with information about how the Standards and Risk Management Division's management team examined opportunities to improve the timeliness of the UCMR program. This team, which represented an internal workgroup of officials responsible for UCMR, regulatory determinations and the CCL programs met regularly from at least July 2014 through November 2015 to discuss these programs and their priorities, to coordinate timing, and to make adjustments as needed. Specific meetings in March 2014 were focused on program coordination and alignment, with further management meetings held to address the development of the proposed rule and the final rule, and additional staff-to-staff coordination on these topics. EPA officials also told GAO that, taking into account the process for developing, proposing, and finalizing the UCMR rule, and considering the benefits of early stakeholder input (such as that received during the 2013 and 2014 meetings EPA convened for UCMR4 discussions), EPA concluded that it was not practical to select contaminants more quickly. Based on the potential for temporal variability with contaminant occurrence, and taking into account prior stakeholder concerns regarding "compressed" monitoring over a shorter period, EPA decided that UCMR 4 monitoring take place over the traditional 3 year timeframe, as indicated in the December 2016 final rule. EPA UMCR officials also said that they share the UCMR monitoring results with the regulatory determinations team on a quarterly basis so that the regulatory determination staff can track the results of the UCMR monitoring in real time. Generally, based on their past experience with UCMR monitoring, UCMR staff are able to understand the occurrence pattern for contaminants before the monitoring is complete, thereby helping the regulatory determinations group use the data as they are making decisions about regulatory determinations.

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