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Basic Information

Unregulated Contaminant Monitoring Regulation 2 (UCMR 2) sampling will occur during 2008-2010. This monitoring cycle includes 25 unregulated contaminants and five associated analytical methods.


Background
The original unregulated contaminant monitoring program (1988-1997) utilized State primacy, and required public water systems (PWSs) serving greater than 500 people to monitor. Then the 1996 amendments to the Safe Drinking Water Act (SDWA) required that EPA establish criteria for a program to monitor unregulated contaminants, and to identify no more than 30 contaminants to be monitored every five years. EPA identified and published unregulated contaminants for the first direct-implementation of UCMR (i.e., UCMR 1), and a revised approach for monitoring, in the Federal Register dated September 17, 1999. UCMR 1 established a tiered monitoring approach, and required all public water systems (PWSs) serving more than 10,000 people and a representative sample of PWSs serving less than 10,001 people to monitor for unregulated contaminants from 2001-2005.

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About this regulation
EPA is requiring select public water systems (PWSs) to monitor for 25 chemicals using five different analytical methods (see table below). All PWSs serving more than 10,000 people, and a representative sample of 800 PWSs serving 10,000 or fewer people, are required to conduct Assessment Monitoring (List 1) for 10 chemicals during a 12-month period during January 2008-December 2010. All PWSs serving more than 100,000 people, 320 selected PWSs serving 10,001 to 100,000 people, and 480 selected PWSs serving 10,000 or fewer people are required to conduct the Screening Survey (List 2) for 15 contaminants during a 12-month period during January 2008-December 2010.

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Why was the UCMR program developed?
The UCMR program was developed in coordination with the Contaminant Candidate List (CCL). The CCL is a list of contaminants that are not regulated by national primary drinking water regulation, are known or anticipated to occur at public water systems, and may warrant regulation under the Safe Drinking Water Act (SDWA). The data collected through the UCMR are stored in the National Contaminant Occurrence Database (NCOD) to support analysis and review of contaminant occurrence, to guide the CCL selection process, and to support the Administrator's determination of whether to regulate a contaminant in the interest of protecting public health.

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How did EPA select these contaminants?
EPA reviewed contaminants that had been targeted through existing prioritization processes, including previous UCMR "reserved" contaminants (i.e., those contaminants for which analytical methods were not yet available), and the Contaminant Candidate List (CCL). Additional contaminants were identified based on current research on occurrence and health effects risk factors. Pesticides that were not registered for use in the United States, contaminants that did not have an analytical reference standard, and contaminants whose analytical methods were not ready for use were removed from the list. EPA further prioritized the remaining contaminants based on more extensive health effects evaluations by the Office of Water’s Office of Science and Technology. These procedures for evaluating health effects scores were developed to support the ranking of contaminants for future CCLs.

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What are the environmental and public health benefits?
The UCMR benefits the environment and public health by providing EPA and other interested parties with scientifically valid data on the occurrence of these contaminants in drinking water, permitting assessment of the population being exposed and the levels of that exposure. This information is the primary source of exposure data for the Agency to determine whether to regulate these contaminants.

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What is the EPA Laboratory Approval Program for UCMR 2?
Laboratories interested in analyzing samples for PWSs subject to the UCMR 2 monitoring requirements need to register for the EPA Laboratory Approval Program. Laboratories need to complete and submit the method-specific application packages. Upon a complete review, qualified laboratories will become eligible to participate in a Proficiency Testing (PT) Program. Laboratories that successfully complete the PT Program will be granted method-specific approval. Laboratories interested in registering for the Laboratory Approval Program should send their request to address below.

UCMR 2 Laboratory Approval Coordinator
US EPA, Technical Support Center
26 West Martin Luther King Drive (MS 140)
Cincinnati, OH 45268

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