United States
Environmental Protection
Agency
The Third Unregulated Contaminant Monitoring Rule (UCMR 3]:
Data Summary, January 2017
EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect data for contaminants
suspected to be present in drinking water, but that do not have health-based standards set under the Safe
Drinking Water Act (SDWA). Every five years EPA develops a new list of UCMR contaminants, largely based on
the Contaminant Candidate List (CCL). The SDWA Amendments of 1996 provide for:
•	Monitoring no more than 30 contaminants per 5-year cycle
•	Monitoring only a representative sample of public water systems (PWSs) serving less than or equal to
10,000 people
•	Storing analytical results in a National Contaminant Occurrence Database (NCOD)
UCMR 3 required monitoring for 30 contaminants (28 chemicals and two viruses) between 2013 and 2015
using analytical methods developed by EPA, consensus organizations or both. This monitoring provides a basis
for future regulatory determinations and/or other actions to protect public health.
This dataset represents the twelfth and final NCOD release of analytical results for UCMR 3. Additional
reference material is available to assist with the assessment of the UCMR 3 data.
•	EPA's UCMR 3 website
•	Instructions for importing and viewing UCMR 3 results
•	Additional information for the UCMR 3 contaminants on the CCL & Regulatory Determination website
To perform additional data analyses, EPA suggests importing each field into your choice of software as text.
Some of the IDs can be misinterpreted as long integer field types when they actually contain alpha characters.
Data are presented as tab delimited text files, with field names included in the first row of each file and no text
•	Select "UCMR 3 Occurrence Data" to find the text file containing ALL results to date (UCMR3_All.txt)
•	Select "UCMR 3 Occurrence Data by State" to find the text files containing ALL results to date for tribes
and states AK-LA (UCMR3_AII_Tribes_AK_LA.txt) and states MA-WY (UCMR3_AII_MA_WY.txt)
•	Select "UCMR 3 Occurrence Data by Method Classification" to find method-specific text files
(\JCMR3_MethodNumber.txt, example UCMR3_200_8 for EPA method 200.8)
•	Text file containing disinfectant residual type (UCMR3_DRT.txt)
•	Text file containing the U.S. Postal Service zip code(s) for all areas served by a PWS
(UCMR3_ZipCodes.txt)
Samples collected at the maximum residence time in the distribution system (MR) were required to be
analyzed for metals (including chromium-6) and chlorate. PWSs monitoring for Method 300.1 (chlorate)
reported disinfectant types. In addition to reporting occurrence data for UCMR 3 target analytes, EPA tasked
its small-system contract-support laboratories with reporting results for sec-butylbenzene, n-propylbenzene,
tellurium, germanium and manganese. These additional unregulated analytes are within the scope of the
methods already being performed for the UCMR analytes. Population categories are based on retail
population as indicated by the Safe Drinking Water Information System (Federal) (SDWIS/FED) as of December
31, 2010.
Office of Water (MS-140)	EPA 815-S-17-001	January 2017
UCMR 3 Data Considerations
qualifier:

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UCMR 3 Data Field Names and Definitions
| Field Name
Definition
PWSID
Public Water System Identification Code, 9-character identification code (Begins with the standard 2-character postal
State abbreviation or Region code, and the remaining seven numbers are unique to each PWS in the state)
PWSName
Name of the Public Water System (PWS)
Size
Size category of the PWS for UCMR, based on retail population as of December 31, 2010: S (< 10,000), L (> 10,000)
FacilitylD
Public Water System Facility Identification Code, 5-digit identification code
FacilityName
Name of the facility at the PWS
FacilityWaterType
Source of water at the facility: SW (surface water), GW (ground water), GU (ground water under the direct influence
of surface water), MX (Any combination of: SW, GW and GU)
SamplePointID
Identification code for each sample point location in the PWS
SamplePointName
Name of the sample point for every sample point ID at a PWS
SamplePointType
Sampling Point Type Code: EP (entry point to the distribution system), MR (distribution system at maximum
residence time)
Associated FacilitylD
The facility ID of the associated MR
AssociatedSamplePointlD
The sample point ID of the associated MR
Disinfectant Type
CLGA (Gaseous Chlorine), CLOF (Offsite Generated Hypochlorite, stored as liquid), CLON (Onsite Generated
Hypochlorite, no storage), CAGC (Chloramine, formed from gaseous chlorine), CAOF (Chloramine, formed from
offsite hypochlorite), CAON (Chloramine, formed from onsite hypochlorite), CLDO (Chlorine Dioxide), OZON (Ozone),
ULVL (Ultraviolet Light), OTHD (All other types of disinfectant), NODU (No Disinfectant Used)
CollectionDate
Date of sample collection (month, day, year)
SamplelD
Identification code for each sample, as defined by the laboratory
Contaminant
Unregulated contaminant being analyzed in UCMR 3
MRL
Minimum Reporting Level defined by UCMR 3 in |ag/L for the chemicals
UCMR 3, January 2017	Page 2 of 12

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Field Name
Definition
MethodID
Identification code of the analytical method
AnalyticalResultsSign
Less than (<) the minimum reporting level (MRL) or equal to (=) a numeric value at or above the MRL
AnalyticalResultValue
Numeric value of the analytical result in |ag/L for the chemicals, null values represent less than MRL
SampleEventCode
Identification code for each sample event. Includes sample event one (SE1), sample event two (SE2), sample event
three (SE3), and sample event four (SE4).
MonitoringRequirement
AM (Assessment Monitoring, List 1), SS (Screening Survey, List 2), PST (Pre-Screen Testing, List 3)
Region
EPA Region (States): 1 (CT, ME, MA, NH, Rl, VT), 2 (NJ, NY, PR (Puerto Rico), VI (Virgin Islands)), 3 (DE, DC, MD, PA,
VA, WV), 4 (AL, FL, GA, KY, MS, NC, SC, TN), 5 (IL, IN, Ml, MN, OH, Wl), 6 (AR, LA, NM, OK, TX), 7 (IA, KS, MO, NE), 8
(CO, MT, ND, SD, UT, WY), 9 (AZ, CA, HI, NV, AS (American Samoa), GU (Guam), MP (Northern Marianas Islands), NN
(Navajo Nation)), 10 (AK, ID, OR, WA)
State
State abbreviation
ZipCode
U.S. Postal Service zip code(s) for all areas being served water by a PWS
UCMR 3, January 2017
Page 3 of 12

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UCMR 3 Chemical Contaminants and Methods
Contaminant
Contaminant Full Name
CAS1 Number
Method ID
Method Name
Monitoring
Requirement
1,2,3-trichloropropane
1,2,3-trichloropropane
96-18-4
524.3
Volatile Organic Compounds
AM
1,3-butadiene
1,3-butadiene
106-99-0
524.3
Volatile Organic Compounds
AM
Chloromethane
methyl chloride
74-87-3
524.3
Volatile Organic Compounds
AM
1,1-dichloroethane
1,1-dichloroethane
75-34-3
524.3
Volatile Organic Compounds
AM
Bromomethane
methyl bromide
74-83-9
524.3
Volatile Organic Compounds
AM
HCFC-22
chlorodifluoromethane
75-45-6
524.3
Volatile Organic Compounds
AM
Halon 1011
bromochloromethane
74-97-5
524.3
Volatile Organic Compounds
AM
1,4-dioxane
1,4-dioxane
123-91-1
522
Synthetic Organic Compound
AM
Vanadium
vanadium
7440-62-2
200.8
Metals
AM
Molybdenum
molybdenum
7439-98-7
200.8
Metals
AM
Cobalt
cobalt
7440-48-4
200.8
Metals
AM
Strontium
strontium
7440-24-6
200.8
Metals
AM
Chromium
total chromium
N/A
200.8
Metals
AM
Chromium-6
chromium-6
18540-29-9
218.7
Chromium-6
AM
Chlorate
chlorate
14866-68-3
300.1
Oxyhalide Anion
AM
PFOS
perfluorooctanesulfonic acid
1763-23-1
537
Perfluorinated Compounds
AM
PFOA
perfluorooctanoic acid
335-67-1
537
Perfluorinated Compounds
AM
PFNA
perfluorononanoic acid
375-95-1
537
Perfluorinated Compounds
AM
PFHxS
perfluorohexanesulfonic acid
355-46-4
537
Perfluorinated Compounds
AM
PFHpA
perfluoroheptanoic acid
375-85-9
537
Perfluorinated Compounds
AM
PFBS
perfluorobutanesulfonic acid
375-73-5
537
Perfluorinated Compounds
AM
173-estradiol
estradiol
50-28-2
539
Hormones
SS
17a-ethynylestradiol
ethinyl estradiol
57-63-6
539
Hormones
SS
Estriol
16-a-hydroxyestradiol
50-27-1
539
Hormones
SS
Equilin
equilin
474-86-2
539
Hormones
SS
Estrone
estrone
53-16-7
539
Hormones
SS
Testosterone
testosterone
58-22-0
539
Hormones
SS
4-androstene-3,17-dione
4-androstene-3,17-dione
63-05-8
539
Hormones
SS
1Chemical Abstract Service
UCMR 3, January 2017	Page 4 of 12

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UCMR 3 Microbiological Contaminants and Methods
Contaminant
Method ID
Method Name
Monitoring Requirement
Enteroviruses
EPA 1615A
Enterovirus cell culture
PST
Enteroviruses
EPA 1615B
Enterovirus RT-qPCR
PST
Noro viruses
EPA 1615C
Norovirus genogroup I with RT-qPCR primer set A
PST
Noro viruses
EPA 1615D
Norovirus genogroup I with RT-qPCR primer set B
PST
Noro viruses
EPA 1615E
Noroviruses genogroup II
PST
Total coliforms
SM 9223B
Colilert®
PST
E.coli
SM 9223B
Colilert®
PST
Enterococci
ASTM D6503-99
Enterolert®
PST
Aerobic spores
SM 9218
Aerobic endospores
PST
Somatic phage
EPA 1602
Bacteriophage
PST
Male specific phage
EPA 1602
Bacteriophage
PST
UCMR 3, January 2017
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UCMR 3 Reference Concentrations for Chemical Contaminants
For the third Unregulated Contaminant Monitoring Rule (UCMR 3) chemicals were being studied at levels that
were often significantly below those in prior UCMR cycles. Importantly, UCMR 3 minimum reporting levels
(MRLs) were established based on the capability of the analytical method, not based on a level established as
"significant" or "harmful." In fact, the UCMR 3 MRLs are often below current "health reference levels" (to the
extent that HRLs have been established).
Results of UCMR 3 measurements should be interpreted accordingly. The detection of a UCMR 3 contaminant
above the MRL does not represent cause for concern, in and of itself. Rather, the implications of the detection
should be judged considering health effects information (which is often still under development or being
refined for unregulated contaminants).
The intent of the following table is to identify draft UCMR reference concentrations, where possible, to
provide context around the detection of a particular UCMR contaminant above the MRL. The draft reference
concentration does not represent an "action level" (EPA requires no particular action1'2 based simply on the
fact that UCMR monitoring results exceed draft reference concentrations), nor should the draft reference
concentration be interpreted as any indication of an Agency intent to establish a future drinking water
regulation for the contaminant at this or any other level. Decisions as to whether or not to regulate the
contaminant in drinking water will continue to be made following the Agency's Regulatory Determination
process. Visit EPA's Regulatory Determination website for more information.
The following key principles guided the development of the table:
(1)	The reference concentrations are based on publicaIly-available health information found in the
following EPA resources: 2012 Drinking Water Standards and Health Advisories, the CCL 4 Contaminant
Information Sheets, the Human Health Benchmark for Pesticides (HHBPs), the Integrated Information
Risk System (IRIS), or the 2014 Preliminary Regulatory Determinations for Contaminants on CCL 3. The
primary/secondary sources of health information vary with respect to scientific rigor from health
assessment to single studies and are cited in the table.
(2)	If health information was available from more than one of the EPA resources listed above, the most
recent health information was used for the draft reference concentrations.
(3)	Where both cancer and non-cancer draft reference concentrations existed, the lower (more
conservative) of the two concentrations was used. For chemicals with reference concentrations based
on a cancer endpoint, the table presents a range of values associated with 10"6 to 10"4 cancer risk. For
chemicals with reference concentrations based on a non-cancer endpoint, the duration of exposure
(short-term, intermediate/long-term, chronic) of the toxicity factor (e.g., Reference Dose) used as the
basis for the reference concentration is shown.
Recognizing that additional health effects information will become available over time, those attempting to
assess UCMR occurrence data are encouraged to visit EPA's Drinking Water Contaminant Human Health
Effects Information website for the most recent information.
1 Consumer Confidence Report (CCR) and Public Notification (PN) reporting requirements (see 40 CFR 141.153(d) and 141.207, respectively) apply
to PWSs; CCR requires particular reporting based on measurements relative to the UCMR method reporting limits (MRLs) defined in 40 CFR 141.40.
2States may establish requirements for drinking water contaminants not yet regulated by EPA, and those requirements may be based on state-
established levels that differ from EPA's reference concentrations. PWSs are responsible for being aware of and complying with their state's
requirements, if any.
UCMR 3, January 2017
Page 6 of 12

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Contaminant
MRL
(ng/L)
Reference
Concentration
(H9/L)
Reference Concentration
based on a Cancer
Endpoint
(Y/N)
EPA Reference(s)
Cobalt
1
70
N
(intermediate exposure)
CCL 4 Contaminant Information Sheets
Molybdenum1
1
40
N
(chronic exposure)
2012 Edition of the Health Advisories Table
Strontium2
0.3
1,500
N
(chronic exposure)
Federal Register Notice for the Preliminary
Regulatory Determinations for Contaminants on
CCL 3
Vanadium3
0.2
21
N
(intermediate exposure)
CCL 4 Contaminant Information Sheets
Chromium (Total)
0.2
100
N
(chronic exposure)
The MCL for the National Primary Drinking Water
Regulation
Chromium-64
0.03
NA
-
-
Chlorate
20
210
N
(chronic exposure)
CCL 4 Contaminant Information Sheets
1,4-dioxane5
0.07
0.35 to 35
Y
2012 Edition of the Health Advisories Table
1,1-dichloroethane5
0.03
6.14 to 614
Y
CCL 4 Contaminant Information Sheets
1,2,3-trichloropropane5'6'7
0.03
0.0004 to 0.04
Y
2009 IRIS Assessment
1	The 2012 Edition of the Health Advisories Table and the CCL4 Contaminant Information Sheets (35 ng/L) have slightly different numbers due to rounding.
2	The reference concentration is based on the HRL cited in the preliminary regulatory determination for strontium [Docket No. EPA-HQ-OW-2012-0155].
3	The ATSDR, 1992 used for the CCL4 Contaminant Information Sheets is no longer publically available and has been replaced by a new assessment (ATSDR, 2012).
The minimum risk level (RfD equivalent) was 0.003 mg/kg/day for minor renal effects in an animal study (ATSDR, 1992) compared to 0.01 mg/kg/day for lack of minor effects in
blood pressure, body weight, and hematological parameters in a human study with a 12 week exposure (ATSDR, 2012).
4	The contaminant is on the IRIS Agenda for either a new assessment or an updated assessment; check status here.
5	Reference Concentration range based on cancer risk of 10"6 to 10"4.
610 s cancer risk < MRL < 10"4 cancer risk.
7 To derive the reference concentration, age dependent adjustment factors were applied to the IRIS oral slope factor of 30 per mg/kg-day (calculated using adult exposure data)
to address presumed early-life susceptibility for this chemical (per EPA's Guidelines for Carcinogen Risk Assessment).
UCMR 3, January 2017
Page 7 of 12

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Contaminant
MRL
(ng/L)
Reference
Concentration
(H9/L)
Reference Concentration
based on a Cancer
Endpoint
(Y/N)
EPA Reference(s)
1,3-butadiene5'6
0.1
0.0103 to 1.03
Y
CCL 4 Contaminant Information Sheets
HCFC-22
(chlorodifluoromethane)8
0.08
NA
-
-
Chloromethane
(methyl chloride)5
0.2
2.69 to 269
Y
CCL 4 Contaminant Information Sheets
Halon 1011
(bromochloromethane)9
0.06
90
N
(chronic exposure)
2012 Edition of the Health Advisories Table
Bromomethane
(methyl bromide)
0.2
140
N
(chronic exposure)
Human Health Benchmark for Pesticides (HHBPs)
PFBS
0.09
NA
-
-
PFHpA
0.01
NA
-
-
PFHxS
0.03
NA
-
-
PFNA
0.02
NA
-
-
PFOS
0.04
0.07
N
(chronic exposure)
Health Advisory and Supporting Documentation
for PFOS
PFOA
0.02
0.07
N
(chronic exposure)
Health Advisory and Supporting Documentation
for PFOA
17a-ethynylestradiol
(ethinyl estradiol)
0.0009
0.035
N
(chronic exposure)
CCL 4 Contaminant Information Sheets
173-estradiol
(estradiol)5
0.0004
0.0009 to 0.09
Y
CCL 4 Contaminant Information Sheets
8	The CCL 4 Contaminant Information Sheets provide a reference level of 31.5 ng/L; the number is based on a single LOAEL from a 1983 study.
9	The 2012 Edition of the Health Advisories Table and the CCL 4 Contaminant Information Sheets (70 ng/L) have slightly different numbers due to rounding.
UCMR 3, January 2017
Page 8 of 12

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Contaminant
MRL
(ng/L)
Reference
Concentration
(H9/L)
Reference Concentration
based on a Cancer
Endpoint
(Y/N)
EPA Reference(s)
Equilin
0.004
0.35
N
(chronic exposure)
CCL 4 Contaminant Information Sheets
Estriol
(16-a-hydroxyestradiol)
0.0008
0.35
N
(chronic exposure)
CCL 4 Contaminant Information Sheets
Estrone
0.002
0.35
N
(chronic exposure)
CCL 4 Contaminant Information Sheets
4-androstene-3,17-dione
0.0003
NA
-
-
Testosterone
0.0001
NA
-
-
UCMR 3, January 2017
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Terms
a)	UCMR Draft Reference Concentration = The reference concentrations are based on publically-available health information found in the
following EPA resources: 2012 Drinking Water Standards and Health Advisories (HAs), the CCL 4 Contaminant Information Sheets (i.e.,
HRLs), the Human Health Benchmark for Pesticides (HHBPs), or the 2014 Preliminary Regulatory Determinations for Contaminants on CCL 3
(i.e., HRLs). The primary/secondary sources of health information vary with respect to scientific rigor from health assessment to single
studies. Many of the contaminants are currently under regulatory review or development and are subject to change as new health
assessments are completed.
b)	MRL = UCMR Minimum Reporting Level. [Note that the Agency for Toxic Substances & Disease Registry (ATSDR) uses the term "MRL" for a
different purpose (i.e., to describe "Minimal Risk Levels"). The UCMR term and the ATSDR term have no relationship to each other.]
c)	HAs = Health advisories. HAs provide information on contaminants that can cause human health effects and are known or anticipated to
occur in drinking water. EPA's health advisories are non-enforceable and non-regulatory and provide technical information to state agencies
and other public health officials on health effects, analytical methodologies, and treatment technologies to assist with risk management
decisions.
d)	HRLs = Health Reference Levels. The CCL process derives HRLs using single studies to health assessments for screening purposes. The CCL
HRLs derived from health assessments are used in the Regulatory Determination process as risk-derived concentrations against which to
evaluate the occurrence data to determine if contaminants may occur at levels of public health concern. HRLs are not final determinations
about the level of a contaminant in drinking water that is necessary to protect any particular population and are derived prior to
development of a complete exposure assessment.
e)	MCL = Maximum Contaminant Level. The highest level of a contaminant allowed in drinking water. MCLs are enforceable standards.
f)	Cancer Risk of 10~6 to 10~4 = the concentration of a contaminant in drinking water corresponding to an excess estimated lifetime cancer risk
of one-in-a-million (lx 10"6) to one-in-ten-thousand (1 x 10~4). The 2012 Drinking Water Standards and Health Advisories provide the cancer
risk at 1 x 10~4. The CCL 4 Contaminant Information Sheets provide the cancer risk at lx 10~6.
g)	LOAEL = Lowest Observed Adverse Effect Level
h)	NA = Not Available
i)	Short-term = Typically refers to animal toxicological studies with an exposure duration of days to weeks.
j) Intermediate/Longer-term = Typically refers to animal toxicological studies with an exposure duration of weeks to months.
k) Chronic = Typically refers to animal toxicological studies with an exposure duration of months to years; representing a lifetime exposure in
humans.
References
2012 Drinking Water Standards and Health Advisories (https://www.epa.gov/dwstandardsregulations/drinking-water-contaminant-human-health-effects-information)
CCL 4 Contaminant Information Sheets (https://www.epa.gov/sites/production/files/2016-ll/documents/815rl6003.pdf)
Human Health Benchmark for Pesticides (HHBPs) (https://ofmpub.epa.gov/apex/pesticides/f?p=109:3)
Announcement of Preliminary Regulatory Determinations for Contaminants on the Third Drinking Water Contaminant Candidate List (https://www.epa.gov/ccl/regulatorv-
determination-3)
Integrated Risk Information System (IRIS) (http://cfpub.epa.gov/ncea/iris2/atoz.cfm)
UCMR 3, January 2017
Page 10 of 12

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January 2017 UCMR 3 Data Summary for Chemical Contaminants
Contaminant
MRL
(Hg/L)
Reference
Concentration
(Hg/L)
Total
number
of results
Number
of
results
>MRL
Number of
resu Its
>Reference
Concentration
% of total
resu Its
>Reference
Concentration
Total
number of
PWSs with
resu Its
Number
of PWSs
with
resu Its
>MRL
Number of
PWSs with
resu Its
>Reference
Concentration
% of PWSs
with results
>Reference
Concentration
1,2,3-trichloropropane
0.03
0.0004 / 0.041
36,848
256
256/1971
0.7% / 0.57O1
4,916
67
67 / 551
1.4% / 1.1%1
1,3-butadiene
0.1
0.0103/1.031
36,848
2
2 / 01
0.005% / 0%1
4,916
2
2 / 01
0.04% / 0%1
Chloromethane
0.2
2.69/2691
36,845
283
20 /01
0.05% / 0%1
4,916
138
8 / 01
0.2% / 0%1
1,1-dichloroethane
0.03
6.14/6141
36,848
835
I/O1
0.003% / 0%x
4,916
244
I/O1
0.02% / 0%1
Bromomethane
0.2
140
36,848
115
0
0%
4,916
49
0
0%
HCFC-22
0.08
NA
36,847
827
--
--
4,916
286
--
--
Halon 1011
0.06
90
36,847
655
0
0%
4,916
309
0
0%
1,4-dioxane
0.07
0.35/351
36,810
4,197
1,081 / 01
2.9 % / 0%1
4,915
1,077
341/ 01
6.9% / 0%1
Vanadium
0.2
21
62,981
37,954
1,680
2.7%
4,922
3,625
163
3.3%
Molybdenum
1
40
62,986
25,377
151
0.2%
4,922
2,546
40
0.8%
Cobalt
1
70
62,982
833
3
0.005%
4,922
247
3
0.06%
Strontium
0.3
1,500
62,913
62,799
1,739
2.8%
4,922
4,922
286
5.8%
Chromium
0.2
100
62,917
31,773
1
0.002%
4,922
3,660
1
0.02%
Chromium-6
0.03
NA
62,837
47,503
--
--
4,919
4,401
--
--
Chlorate
20
210
62,859
34,426
9,796
15.6%
4,918
3,391
1,896
38.6%
PFOS
0.04
0.07
36,972
292
124
0.3%
4,920
95
46
0.9%
PFOA
0.02
0.07
36,972
379
32
0.09%
4,920
117
13
0.3%
PFNA
0.02
NA
36,972
19
--
--
4,920
14
--
--
PFHxS
0.03
NA
36,971
207
--
--
4,920
55
--
--
PFHpA
0.01
NA
36,972
236
--
--
4,920
86
--
--
PFBS
0.09
NA
36,972
19
--
--
4,920
8
--
--
17(3-estradiol
0.0004
0.0009 / 0.091
11,795
4
I/O1
0.008% / 0%x
1,201
2
I/O1
0.08% / 0%1
17a-ethynylestradiol
0.0009
0.035
11,796
4
0
0%
1,201
4
0
0%
Estriol
0.0008
0.35
11,796
4
0
0%
1,201
4
0
0%
Equilin
0.004
0.35
11,796
0
0
0%
1,201
0
0
0%
Estrone
0.002
0.35
11,796
0
0
0%
1,201
0
0
0%
Testosterone
0.0001
NA
11,795
72
--
--
1,201
65
--
--
4-androstene-3,17-dione
0.0003
NA
11,796
101
--
--
1,201
77
--
--
1Where two reference concentrations are listed, the first number is associated with a 10 6 cancer risk; the second number a 10 4 cancer risk.
Where two results are presented the first number is associated with the first reference concentration; the second number is associated with the second reference concentration.
UCMR 3, January 2017
Page 11 of 12

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January 2017 UCMR 3 Data Summary for Microbiological Contaminants
Contaminant
MRL
Unit
Total number
of results
Number of
results >MRL
Total number of
PWSs with
results
Number of
PWSs with
results >MRL
Aerobic spores
1
SFOVlOO mL2
1,047
317
793
252
E. coli
1
MPN3/100 mL
1,045
3
791
3
Enterococci
1
MPN/100 mL
1,044
41
792
41
Enteroviruses (cell culture)
0.002
MPN/L4
1,044
2
789
2
Enteroviruses (RT-qPCR5)
0.398
GC6/L
1,044
6
789
6
Male specific phage
1
PFU7/100 mL
1,029
14
783
14
Noroviruses GIA8
0.398
GC/L
1,044
4
789
4
Noroviruses GIB9
0.398
GC/L
1,044
2
789
2
Noroviruses Gil10
0.398
GC/L
1,044
4
789
4
Somatic phage
1
PFU/100 mL
1,029
5
783
5
Total coliforms
1
MPN/100 mL
1,045
57
791
53
^FO = Spore Forming Units	6GC = Genomic Copies
2mL = milliliters	7PFU = Plaque Forming Units
3MPN = Most Probable Number	8Noroviruses GIA = qPCR analysis of Norovirus genogroup I with RT-qPCR primer set A
4L = liters	9Noroviruses GIB = qPCR analysis of Norovirus genogroup I with RT-qPCR primer set B
5RT-qPCR = Reverse Transcription-Polymerase Chain Reaction	10Noroviruses Gil = qPCR analysis of Norovirus genogroup II
UCMR 3 Minimum Reporting Levels for Microbiological Contaminants
Under UCMR 3 microbe analytical results are reported as "below", "at" or "above" MRL. UCMR 3 MRLs were established based on the capability of
the analytical method.
It is important to note that microbial contamination can be transient in nature and microbial detections under UCMR 3 should be interpreted in the
context of the time samples were collected. However, the presence of any UCMR 3 microbe indicates a potential vulnerability of the PWS to
contamination.
UCMR 3, January 2017
Page 12 of 12

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