Document ID: EPA-HQ-OW-2016-0715-0057
Agency: epa
Document Type: Notice
Title: Recommended Human Health Recreational Ambient Water Quality Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin
Posted Date: 2019-06-06T04:00Z

[Federal Register Volume 84, Number 109 (Thursday, June 6, 2019)]
[Notices]
[Pages 26413-26414]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-11814]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OW-2016-0715; FRL-9994-58-OW]

Recommended Human Health Recreational Ambient Water Quality 
Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.

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SUMMARY: The Environmental Protection Agency (EPA) announces the 
release of final Recommended Human Health Recreational Ambient Water 
Quality Criteria or Swimming Advisories for Microcystins and 
Cylindrospermopsin. These are the recommended concentrations of the 
cyanotoxins microcystins and cylindrospermopsin in recreational waters 
protective of human health while swimming or participating in primary 
contact recreational activities on the water. The recommended values 
found in this document supplement the 2012 Recreational Water Quality 
Criteria to provide further public health protection for potentially 
hazardous conditions found in ambient recreational waters.
    This document was released for 90-day public comment in the Federal 
Register on December 16, 2016. The EPA has considered the comments, 
revised the draft document, as appropriate, and published this final 
document to provide recommendations for states and authorized tribes 
interested in establishing water quality standards (WQS) under the 
Clean Water Act (CWA). Alternatively, these same values can be used as 
the basis for swimming advisories in recreational waters to protect the 
public. States and authorized tribes may also wish to consider using 
these values as both WQS and swimming advisory values.

FOR FURTHER INFORMATION CONTACT: John Ravenscroft, Health and 
Ecological Criteria Division, Office of Water (Mail Code 4304T), 
Environmental Protection Agency, 1200 Pennsylvania Avenue NW, 
Washington, DC 20460; telephone number: (202) 566-1101; email address: 
ravenscroft.john@epa.gov.

SUPPLEMENTARY INFORMATION: 

I. General Information

A. How can I get copies of this document and other related information?

    1. Docket. The EPA has established a docket for this action under 
Docket ID No. EPA-HQ-OW-2016-0715. Publicly available docket materials 
are available either electronically through www.regulations.gov or in 
hard copy at the Water Docket in the EPA Docket Center, (EPA/DC) EPA 
West, Room 3334, 1301 Constitution Ave. NW, Washington, DC. The EPA 
Docket Center Public Reading Room is open Monday through Friday from 
8:30 a.m. to 4:30 p.m., excluding legal holidays. The telephone number 
for the Public Reading Room is (202) 566-1744, and the telephone number 
for the Water Docket is (202) 566-2426.
    2. Electronic Access. You may access this Federal Register document 
electronically from the Government Printing Office under the Federal 
Register listings FDSys (http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR).

II. What are microcystins and cylindrospermopsin and why is the EPA 
concerned about them?

    Microcystins and cylindrospermopsin are toxins that can be produced 
by a variety of cyanobacteria species. Cyanobacteria, also commonly 
referred to as blue-green algae, are photosynthetic bacteria that live 
in many diverse habitats. Under some conditions, cyanobacteria can 
proliferate to high densities in surface waters, creating a bloom, and 
produce toxins that are harmful to humans, the environment, and 
animals. Excessive growth of cyanobacteria in surface waters can lead 
to situations in which elevated levels of cyanotoxins are more likely, 
however, exposure to cyanotoxins can occur even when there are no 
visible signs of a bloom.
    Studies indicate that, at certain concentrations, short-term and 
long-term adverse effects from oral exposure of microcystins and 
cylindrospermopsin include liver and kidney damage. Additionally, 
studies demonstrate that recreational exposures to these cyanotoxins 
can lead to headaches, sore throats, vomiting and nausea, stomach pain, 
dry cough, diarrhea, blistering around the mouth, and pneumonia.

[[Page 26414]]

III. Information on the Recommended Recreational Ambient Water Quality 
Criteria or Swimming Advisories (AWQC/SA) for the Cyanotoxins 
Microcystins and Cylindrospermopsin

    The EPA's recommended AWQC/SA identify the following concentrations 
of microcystins and cylindrospermopsin that would be protective of 
human health given a primary contact recreational exposure scenario: 8 
[micro]g/L for microcystins and 15 [micro]g/L for cylindrospermopsin. 
For both cyanotoxins, the recommended duration and frequency depend on 
their application as a water quality criterion or a swimming advisory.
    These values are based on the exposure of recreating children, due 
to their higher exposures compared to other age groups. Given that 
cyanobacterial blooms typically are seasonal events, recreational 
exposures are likely to be episodic, and may be short-term in nature. 
If adopted as a WQS, for impairment assessment and listing purposes, 
the EPA recommends states and authorized tribes use 10-day assessment 
periods, not a rolling 10-day period, over the course of a recreation 
season to evaluate ambient water body condition and recreational use 
attainment. The 10-day period links the water body assessment period to 
the adverse health effects observed from ingestion of the toxins over 
short-term exposures. If toxin concentrations are higher than the 
criterion magnitude during a 10-day assessment period, then the EPA 
recommends that states and authorized tribes consider that event an 
excursion from the recreational criteria. The EPA recommends that when 
more than three excursions occur within a recreational season and that 
pattern reoccurs in more than one year, it is an indication the water 
quality has been or is becoming degraded and a water body may not be 
supporting the recreational use. The EPA recommends that states and 
authorized tribes indicate the number of years the pattern of 
degradation can occur and not impair the recreational use. If adopted 
as a swimming advisory to protect swimmers at a beach, the EPA 
recommends these values not be exceeded on any single day.
    These recommended AWQC/SA supplement the EPA's 2012 Recreational 
Water Quality Criteria to provide further public health protection when 
elevated levels of these cyanotoxins are found in ambient recreational 
waters. The recommended AWQC/SA are based on the same peer-reviewed 
science used to develop the EPA's 10-Day Drinking Water Health 
Advisories for these same cyanotoxins, published in 2015. The criteria 
document includes information on the latest scientific knowledge 
related to human health effects from exposure to cyanobacteria and 
cyanotoxins, discussion of other domestic and international 
governmental and Agency guidelines for recreational waters, and 
information on incidents involving exposure of domestic pets and other 
animals to cyanotoxins.
    States and authorized tribes can consider using the recommended 
cyanotoxin values as swimming advisories in making decisions whether to 
close, open, or warn about concerns in recreational waters in a manner 
consistent or similar to their current recreational water advisory 
programs. The recommended cyanotoxin values in these CWA section 304(a) 
recommended criteria, even if used as swimming advisories, are not 
regulations, and thus do not constitute legally binding requirements.

IV. What are clean water act section 304(a) water quality criteria?

    CWA section 304(a) water quality criteria are recommendations 
developed by the EPA under authority of the CWA that reflect the latest 
scientific knowledge on the type and extent of all identifiable effects 
on health and welfare of aquatic species and human health. CWA section 
304(a) recommended criteria do not reflect consideration of economic 
impacts or the technological feasibility of meeting pollutant 
concentrations in ambient water.
    CWA section 304(a) recommended criteria provide guidance to states 
and authorized tribes in developing and adopting WQS that protect 
specific designated uses; in this case recreation. The EPA's water 
quality criteria recommendations are not regulations. Thus, the EPA's 
recommended criteria do not constitute legally binding requirements. 
States and authorized tribes may adopt other scientifically defensible 
water quality criteria that differ from these recommendations. When 
adopting new or revised WQS, the states and authorized tribes must 
adopt criteria that are scientifically defensible and protective of the 
designated uses of the bodies of water. States and authorized tribes 
have the flexibility to do this by adopting criteria based on (1) the 
EPA's recommended criteria, (2) the EPA's criteria modified to reflect 
local conditions, or (3) other scientifically defensible methods. 
Cyanotoxins are not part of the 40 CFR part 423, Appendix A list of 126 
priority pollutants, therefore states and authorized tribes are not 
required to adopt criteria for these cyanotoxins.

V. What is the relationship between the water quality criterion and 
your state or authorized tribal water quality standards?

    As part of the WQS triennial review process defined in CWA section 
303(c)(1), the states and authorized tribes are responsible for 
maintaining and revising WQS. WQS consist of designated uses, water 
quality criteria to protect those uses, a policy for antidegradation, 
and may include general policies for application and implementation. 
CWA section 303(c)(1) requires states and authorized tribes to review 
and modify, as appropriate, their WQS at least once every three years.
    States and authorized tribes must adopt water quality criteria that 
protect designated uses. Consistent with the Agency's regulations at 40 
CFR 131.11(a), protective criteria must be based on a sound scientific 
rationale and contain sufficient parameters or constituents to protect 
the designated uses. Criteria may be expressed in either narrative or 
numeric form.
    The EPA's regulation at 40 CFR 131.20(a) provides that if a state 
or authorized tribe does not adopt new or revised criteria parameters 
for which the Agency has published new or updated recommendations, then 
the state or authorized tribe shall provide an explanation when it 
submits the results of its triennial review to the Regional 
Administrator consistent with CWA section 303(c)(1).

VI. What Changed Between the Draft and Final Criteria

    Changes in the final criteria document, compared to the December 
2016 draft posted for public comment, include revised (higher) values 
for both microcystins and cylindrospermopsin and modified recommended 
duration and frequency components. In response to public comments, the 
Agency did not apply a relative source contribution term in deriving 
the final recommended criteria. Additionally, the incidental ingestion 
information for children was updated to reflect a study published in 
2017. The updated ingestion rate was the primary factor for the change 
in the recommended values.

    Dated: May 22, 2019.
David P. Ross,
Assistant Administrator, Office of Water.
[FR Doc. 2019-11814 Filed 6-5-19; 8:45 am]
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