United States Office of Water EPA 815-F-01-008
Environmental Protection (4607) April 2001
Agency Washington, DC 20460 www.epa.gov/safewater
4MEPA Revisions to the Unregulated
Contaminant Monitoring Rule
Fact Sheet
EPA has revised the Unregulated Contaminant Monitoring Rule (UCMR), as required by
the 1996 Amendments to the Safe Drinking Water Act. The rule was published on
September 17, 1999, and supplemented on March 2, 2000 and January 11, 2001. The data
generated by the new UCMR will be used to evaluate and prioritize contaminants on the
Drinking Water Contaminant Candidate List, a list of contaminants EPA is considering for
possible new drinking water standards. This data will help to ensure that future decisions on
drinking water standards are based on sound science.
The new rule includes:
• Three different lists of contaminants based on the availability of established analytical
methods
• Requirements for all large public water systems (PWS) and a representative sample of
small PWS to monitor for those contaminants on List 1
• Requirements for selected large and small PWS to monitor for those contaminants on List
2
• Requirements to submit the monitoring data to EPA and the States for inclusion in the
National Drinking Water Contaminant Occurrence Database
° Requirements to notify consumers of the availability of the results of monitoring
• Requirements to include detected contaminants in Consumer Confidence Reports
The UCMR Monitoring List (see Table 1 below) includes all 34 contaminants in the
Contaminant Candidate List, Occurrence Priorities column, and two radionuclides that
emerged during regulation development. The UCMR Monitoring List is comprised of three
separate lists based on analytical methods readiness and current contaminant occurrence data:
List 1 for Assessment Monitoring, List 2 for Screening Surveys and List 3 for Pre-Screen
Testing.
The Safe Drinking Water Act, as amended in 1996, requires EPA to limit monitoring
requirements to 30 contaminants in any 5-year cycle. Since many of the contaminants still
have analytical methods under development, the success of the methods development efforts
will dictate which contaminants will be monitored in the 5-year cycle. While the UCMR
Monitoring List has 36 contaminants on it, the regulation will only require monitoring for the
12 contaminants on List 1, beginning in 2001 at all large PWS and the selected small PWS.
It also requires monitoring for the List 2 contaminants, which have methods listed, beginning
in 2001.
List 1 - Assessment Monitoring
List 1 includes 12 chemical contaminants for which analytical methods exist. EPA has
information on their occurrence in drinking water for some PWS, but not a national estimate
of their extent of occurrence. Monitoring for List 1 contaminants at PWS is the specific
action resulting from the September 17, 1999 rule.
Monitoring of List 1 (referred to as Assessment Monitoring) contaminants will occur at
approximately 2,800 large PWS and a representative sample of 800 (out of 66,000) small
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PWS. Transient water systems are not required to monitor nor are systems which purchase
100% of their water. The monitoring results from these systems will be used to estimate
national occurrence of the 12 contaminants on List 1. The 800 small systems will be selected
at random from all small systems. Each State will have a number of systems allocated to it,
based on population served.
Surface water systems will monitor quarterly during a 1-year period and ground water
systems will monitor twice in a 1-year period. Assessment Monitoring must be done within
the three years of 2001 to 2003, which will allow coordination with the 3-year compliance
(for regulated contaminants) monitoring cycle. One of these quarterly or semiannual
sampling events must occur in the most vulnerable period of May through July, or an
alternate vulnerable period designated by the State, to ensure monitoring of potentially higher
contaminant concentrations.
SDWA requires EPA to pay for the reasonable testing costs for the representative sample
of small systems. The estimated average annual cost for monitoring List 1 contaminants is
$8.4 million, of which the average annual cost of the representative sample to EPA is $2.0
million. The average costs to individual systems required to monitor are: small systems
serving 10,000 or fewer persons, $21; and large systems serving more than 10,000 persons,
$1,730.
List 2 - Screening Surveys
List 2 contaminants are those for which analytical methods have just been developed and
for which EPA has less occurrence data than the contaminants on List 1. There are 13
organic chemicals and one microorganism which must be monitored for List 2. Monitoring
for List 2 (referred to as Screening Survey) contaminants will occur with the promulgation of
the January 11, 2001 rule. The monitoring program will be the same as that for List 1, but
only for a randomly selected set of 300 large and small systems. This will occur in two
phases. The Screening Survey for the 13 List 2 chemical contaminants will occur in 2001 at
selected small systems and in 2002 at selected large systems. The Screening Survey for the
List 2 microorganism (i.e., Aeromonas) will occur in 2003 (pending promulgation of a
UCMR Methods Update Federal Register Notice (MUFRN)) for all selected systems. Any
occurrence of a List 2 contaminant may indicate the need for more extensive national
monitoring and that this contaminant should be included in the next cycle of List 1
monitoring.
List 3 - Pre-Screen Testing
List 3 contaminants include seven microorganisms known to have health effects and two
radionuclides. These contaminants have recently emerged as drinking water concerns and, in
most cases, only have methods in an early stage of development. Monitoring of List 3
(referred to as Pre-Screen Testing) contaminants will be performed only after future
rulemaking specifies methods. It will need to be determined whether a listed contaminant
occurs in sufficient frequency in the most vulnerable systems or sampling locations to
warrant its being included in future Assessment Monitoring qr Screening Surveys. EPA will
also be evaluating the method performance for List 3 contaminants. EPA will select up to
200 large and small systems from State nominations of systems believed to be most
vulnerable to List 3 contaminants. Because these methods are expected to be expensive,
since they are labor intensive, the monitoring program will likely be implemented on a
semiannual basis.
The use of this tiered approach for implementing the three monitoring lists provides the
maximum capability to monitor up to the statutory limit of no more than 30 contaminants in
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any 5-year monitoring cycle. Therefore, as List 3 contaminants are found to occur in PWS,
they may move up to List 2, and likewise, List 2 contaminants may move up to List 1, in
2004, when the UCMR is revised again. The law requires that EPA publish a new
contaminant monitoring list every 5 years.
State-EPA Implementation Partnership
SDWA provides for State Monitoring Plans for small systems included in the national
representative sample. The rule provides the opportunity for States to work with these small
systems to ensure the highest data quality. This opportunity includes establishing a
Partnership Agreement between the State and EPA for States to accept or modify the initial
monitoring plan, determine an alternate vulnerable monitoring time, modify the timing of
monitoring to coordinate with compliance monitoring, identify alternate sampling points,
notify systems of monitoring responsibilities, provide instructions to small systems,
participate in Screening Survey for List 2 and Pre-Screen Testing for List 3, and provide
additional locational information for systems.
Table 1. UCMR Monitoring List
LIST1
Assessment Monitoring of
Contaminants with Available
Methods
2,4-dinitrotoluene
2,6-dinitrotoluene
Acetochlor
DCPA mono-acid degradate
DCPA di-acid degradate
4,4'-DDE
EPTC
Molinate
MTBE
Nitrobenzene
Perchlorate
Terbacil
LIST 2
Screening Surveys of
Contaminants with Methods
Just Developed
1,2-diphenylhydrazine
2-methyl-phenol
2,4-dichlorophenol
2,4-dinitrophenol
2,4,6- trichlorophenol
Diazinon
Disulfoton
Diuron
Fonofos
Linuron
Nitrobenzene
Prometon
Terbufos
Aeromonas1
Alachlor ESA2 .
RDX2
LIST 3
Pre-Screen Testing of
Contaminants Needing
Research on Methods2
Lead-210
Polonium-210
Cyanobacteria
Echoviruses
Coxsackieviruses
Helicobacter pylori
Microsporidia
Caliciviruses
Adenoviruses
1 Monitoring will occur pending promulgation of a UCMR MUFRN.
2 The monitoring period for Alachlor ESA, RDX and all List 3 contaminants will be
performed only after future rulemaking specifies methods.
Other Information
For general information on the Unregulated Contaminant Monitoring Regulation, contact
the Safe Drinking Water Hotline, at 800-426-4791. The Safe Drinking Water Hotline is open
Monday through Friday, excluding Federal holidays, from 9:00 a.m. to 5:30 p.m. EST.
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