4%	United States
Environmental Protection
hI M % Agency
The Fourth Unregulated Contaminant Monitoring Rule (UCMR 4)
Cyanotoxins - Fact Sheet for Assessment Monitoring
Overview
EPA published the "Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 4) for Public Water Systems and
Announcement of Public Meeting" on December 20, 2016 (81 FR 92666). UCMR 4 includes Assessment Monitoring for a total
of 30 chemical contaminants including nine cyanotoxins and one cyanotoxin group. UCMR 4 also requires Assessment
Monitoring for:
•	Three brominated haloacetic acid (HAA) disinfection byproducts groups and two associated indicators (TOC and
bromide).
•	Seventeen additional contaminants including two metals, eight pesticides plus one pesticide manufacturing
byproduct, three alcohols and three semivolatile organic chemicals.
Monitoring under UCMR 4 will occur from 2018-2020. For more information on these contaminants, please refer to the
respective UCMR 4 Fact Sheets.
Assessment Monitoring (Cyanotoxins)
Freshwater cyanobacterial blooms may be composed of a single-species or variety of toxic and non-toxic strains.
Cyanotoxins are produced and contained within the actively growing cyanobacterial cells, and can be released into the
surrounding water.
Contaminant
CASRN1
MRL2 (ng/L)
Method
"total microcystins"
N/A
0.3
EPA 546
microcystin-LA
96180-79-9
0.008
EPA 544
microcystin-LF
154037-70-4
0.006
EPA 544
microcystin-LR
101043-37-2
0.02
EPA 544
microcystin-LY
123304-10-9
0.009
EPA 544
microcystin-RR
111755-37-4
0.006
EPA 544
microcystin-YR
101064-48-6
0.02
EPA 544
nodularin
118399-22-7
0.005
EPA 544
anatoxin-a
64285-06-9
0.03
EPA 545
cylindrospermopsin
143545-90-8
0.09
EPA 545
1.	CASRN - Chemical Abstracts Service Registry Number
2.	MRL - Minimum Reporting Level
¦	Applicable Water Systems: Community water systems (CWSs) and non-transient non-community water systems
(NTNCWSs) serving more than 10,000 retail customers (i.e., large systems) and a representative sample of 800 CWSs and
NTNCWSs serving 10,000 or fewer retail customers (i.e., small systems). Systems using surface water or ground water under
the direct influence of surface water are required to sample; ground water systems are excluded from cyanotoxin
monitoring.
¦	Timeframe and Frequency: Systems will take samples twice a month for four consecutive months (total of eight sampling
events), during the monitoring timeframe of March through November (excludes December, January and February).
¦	Monitoring Locations: Three samples for cyanotoxin analysis will be collected at the entry point to the distribution system
(EPTDS). One sample will be collected for total microcystins analysis by EPA Method 546 (Adda specific enzyme linked
Office of Water (MS-140)	EPA 815-F-16-008	December 2016

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immunosorbent assay (ELISA)), the second for identification of specific microcystins by analysis using EPA Method 544, and
the third for cylindrospermopsin and anatoxin-a by EPA Method 545.
o If the Adda ELISA result is less than 0.3 micrograms per liter (ng/L) (i.e., the reporting limit for total microcystins),
then the sample collected for Method 544 will not be analyzed for that sample event, and only the Adda ELISA
result will be reported to EPA through the Safe Drinking Water Accession and Review System (SDWARS).
o If the Adda ELISA result is greater than or equal to 0.3 ng/L, the result will be reported to EPA and the EPA Method
544 sample will be analyzed to identify and quantify the six specific microcystin congeners and nodularin.
o Cylindrospermopsin and anatoxin-a will be analyzed by EPA Method 545.
¦	Laboratories: Samples must be analyzed by EPA UCMR approved laboratories.
¦	Occurrence Data: The analytical results from UCMR 4 are stored in the National Contaminant Occurrence Database (NCOD).
For a summary of the NCOD results, tips for querying NCOD, and health effects information (including reference
concentrations, where available), please refer to the UCMR 4 Data Summary document.
Critical Deadlines and Requirements
Following Rule Publication
Due Date
Requirement
Report
through
SDWARS1
Contact
Sampling
Coordinator2
December 31, 2017
Large systems must update contact information, zip code(s),
sampling location(s), inventory information and monitoring
schedule. With the exception of monitoring schedule
changes, any subsequent changes must be submitted within
30 days of the change occurring. EPA will coordinate with the
small systems to collect the contact information, zip code(s)
and inventory information. After December 31, 2017, systems
must provide an explanation for any requested schedule
change and obtain EPA approval of the change.
X
X
(after
December
31, 2017)
February 21, 2017
Laboratories seeking approval must submit a registration
form to participate in the laboratory approval process.

X
April 19, 2017
Laboratories must complete and submit the necessary
laboratory approval application materials.

X
Following Sample Collection
Due Date
Requirement
Report
through
SDWARS1
Contact
Sampling
Coordinator2
Within 120 days of
sample collection
Laboratories post data to SDWARS.
X

Within 60 days of
lab posting data
PWSs review and approve the data. If the PWS has not taken
action after 60 days, the data are considered approved and
ready for state and EPA review.
X

1.	Safe Drinking Water Accession and Review System.
2.	Contact via email at UCMR Sampling Coordinator(5)epa.gov.
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Data Elements
EPA will collect the data elements described in the table below via SDWARS 4, an updated version of the data reporting
system used in previous UCMR actions. The final four data elements bolded in the table below are exclusively cyanotoxin data
elements, and will include "yes" or "no" questions with a corresponding drop down menu of options. These elements were
added to understand source water quality at the time the EPTDS samples are collected.
Public Water System
Identification
(PWSID) Code
Sampling Point
Identification Code
Sample Collection Date
Analysis Batch
Identification Code
Laboratory
Identification Code
Public Water System
Name
Sampling Point Name
Sample Identification
Code
Analysis Date
Sample Event Code
Public Water System
Facility Identification
Code
Sampling Point Type
Code
Contaminant
Sample Analysis Type
Bloom Occurrence
Public Water System
Facility Name
Disinfectant Type
Analytical Method
Code
Analytical Results-Sign
Cyanotoxin
Occurrence
Public Water System
Facility Type
Treatment Information
Extraction Batch
Identification Code
Analytical Result-
Measured Value
Indicator of
Possible Bloom -
Treatment
Water Source Type
Disinfectant Residual
Type
Extraction Date
Additional Value
Indicator of
Possible Bloom -
Source Water
Quality Parameters
Additional Information
The Public Notification Rule (40 CFR 141.207) requires PWSs to notify the persons served of the availability of the
results no later than 12-months after monitoring results are known. CWSs may include their public notice within
their Consumer Confidence Reports (CCRs).
Under the Consumer Confidence Report (CCR) Rule (40 CFR 141.153(d)) requires CWSs to report the monitoring
results whenever unregulated contaminants are detected. CCRs are to be sent to all billing customers each year by
July 1. (The CCR Rule does not apply to non-community water systems). To obtain a copy of your CCR, you should
contact your water supplier or you may find information for how to obtain a copy of the CCR in your water bill.
Additional information about the CCR including detains on reporting requirements can be found on the CCR
Homepage.	
For More Information
¦	Safe Drinking Water Hotline: 1-800-426-4791
¦	CDX/SDWARS Help Desk: 1-888-890-1995
¦	UCMR Homepage
¦	Cvanotoxins in Drinking Water Homepage
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