NC Triennial Kickoff Letter 2023

October 11, 2023

Mr. Paul Wojoski
Classifications and Standards Branch Chief
Division of Water Resources 
North Carolina Department of Environmental Quality
512 North Salisbury Street  
1611 Mail Service Center 
Raleigh, North Carolina  27699-1617 

Dear Mr. Wojoski:

Section 303(c)(1) of the Clean Water Act (CWA) requires that a state shall, from time to time, but at
least once every three years, hold public hearings to review its water quality standards (WQS) and, as
appropriate, modify and adopt standards. Consistent with this requirement, North Carolina is
projected to have its public hearing(s) in July 2024 to solicit comments from the public regarding what
revisions, if any, may be appropriate to North Carolina’s water quality standards. The purpose of this
letter is for the U.S. Environmental Protection Agency (EPA) to provide suggestions for items to be
considered as part of the upcoming triennial review as the state prepares for its public hearing and
drafts any potential proposed revisions. We offer the following comments for your consideration.

Human Health Criteria

Currently the North Carolina Division of Water Resources (DWR) has established WQS for human
health based on previous EPA guidance and recommendations. In June 2015, the EPA issued the
Updated Ambient Water Quality Criteria for the Protection of Human Health (2015 Update). The
updated recommendations for 94 chemical pollutants reflect new science and policies including
updated fish consumption rate, body weight, drinking water intake, health toxicity values,
bioaccumulation factors, and relative source contributions. There was also a 2017 IRIS assessment for
benzo(a)pyrene, which addresses several chemicals that were included in the 2015 Update, that should
be considered. The 2015 Update, combined with any updated exposure factors, represents the
Agency’s most current recommendations and are what the state should consider when making any
revisions. These human health criteria updates can be found by contacting the EPA or on the EPA’s
website at https://www.epa.gov/wqc/human-health-water-quality-criteria-and-methods-toxics.

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In conversations with DWR staff, staff have requested clarification regarding the option to move
forward with a two-triennial plan, which envisions only revising the criteria for a specific set of existing,
listed pollutants for human health criteria during this triennial review, for which updated science is not
currently reflected in Subchapter 02B within Title 15A of the North Carolina Administrative Code, and
completing the remaining pollutant updates, for those parameters not currently listed by name within
Subchapter 02B, in its next triennial review. EPA expects any revisions which are made to be based on
scientifically defensible methods and reflect a consistent approach in the selection of risk factors and
input values, among all revisions that are made throughout the WQS regulations. My staff are available
to provide early review(s) of any draft regulations. Lastly, if North Carolina proceeds with the two-
triennial plan, we recommend staff describe the path forward clearly to the public as DWR prepares its
public notice and hearing materials, including how it will use its narrative criteria provisions for
implementing any translations of the narrative criteria for toxics, if needed in the interim before all
updates are completed.

Recreational and Aquatic Life Criteria

In May 2019, the EPA published national recommendations for human health recreational water
quality criteria/swimming advisories for microcystins and cylindrospermopsin. States can adopt the
cyanotoxin recommended criteria into WQS or use as swimming advisory levels to protect against the
harmful effects related to cyanotoxins. Information on these criteria recommendations can be found
on the EPA website at https://www.epa.gov/wqc/recreational-water-quality-criteria-and-methods. The
EPA has also published several new and updated criteria recommendations for the protection of
aquatic life that the state should review and consider for adoption, including ammonia, carbaryl,
diazinon, nonylphenol, and aluminum. Information on criteria recommendations can be found on the
EPA website at https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-
criteria-table. We encourage North Carolina to consider making changes to reflect these updated
recommendations during the triennial review.

Nutrient Criteria

The EPA encourages the state to continue its progress towards developing numeric nutrient criteria in
support of the state’s 2019 Nutrient Criteria Development Plan to ensure that state waters are
protected from nutrient pollution. The state’s ongoing efforts, in conjunction with the Scientific
Advisory Council (SAC), to develop clarity criteria, are notable, and EPA staff are available to offer any
technical support the state needs to ensure the current SAC recommendations complete the
administrative process for adoption. As the state continues its other waterbody and/or additional
nutrient parameter development efforts, we want to highlight the following recent nutrient specific
recommendations published by the Agency.

Development of nutrient criteria for both nitrogen (N) and phosphorus (P) should be considered for
effective nutrient management, as noted in EPA’s document, Preventing Eutrophication: Scientific
Support for Dual Nutrient Criteria, to be effective to protect designated uses, downstream waters, and
the threat of harmful algal blooms. As noted in the EPA’s document, Preventing Eutrophication:
Scientific Support for Dual Nutrient Criteria, to be effective to protect designated uses, downstream
waters, and the threat of harmful algal blooms, development of nutrient criteria for both nitrogen (N)
and phosphorus (P) should be considered for nutrient management. The EPA looks forward to the

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opportunity to continue working with the state early on in its criteria development process and will
provide any needed resources to assist in the continued development of numeric nutrient criteria,
including both N and P. The EPA’s document on preventing eutrophication and support for dual
nutrient criteria can be found on the EPA website at
https://www.epa.gov/sites/default/files/documents/nandpfactsheet.pdf. The EPA also recently
published its final recommended Ambient Water Quality Criteria to Address Nutrient Pollution in Lakes
and Reservoirs which can be found on the EPA website at https://www.epa.gov/nutrient-policy-
data/ambient-water-quality-criteria-address-nutrient-pollution-lakes-and-reservoirs. The EPA
recommends that the state review the new recommended criteria and consider them for adoption.

Hydrologic WQS

In 2016, the Final EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrologic
Alteration (EPA-USGS Technical Report) was published to provide scientific information for states and
tribes to advance the protection of aquatic life in rivers and streams through the development of
hydrologic water quality standards. Over the past two decades, the state-of-the-science to understand
and quantify the hydrologic conditions necessary to support aquatic life and other uses has evolved
considerably. Pollution, caused by alterations of flow in a waterbody, can affect the physical and
chemical characteristics of waterbodies in predictable ways. These changes can have a significant
detrimental impact on biology, including impacting natural aquatic flora and fauna. According to the US
Geological Survey, hydrologic alteration may be the primary cause of ecological impairment in river
and stream ecosystems in the United States. The effects of climate change are predicted to magnify
and exacerbate these impacts. The EPA-USGS Technical Report includes information that the states and
tribes are encouraged to use to develop and implement scientifically sound, protective hydrologic
WQS. Restoring and maintaining hydrologic conditions will support aquatic life uses and has been
shown to increase system resilience to the effects of climate change. The 2016 Report can be found at
https://www.epa.gov/sites/default/files/2016-12/documents/final-aquatic-life-hydrologic-alteration-
report.pdf. North Carolina is encouraged to consider development of narrative hydrologic standards to
protect aquatic life designated uses.

Water Quality Standards Regulatory Revision

In 2015, the EPA updated the federal WQS regulations at 40 CFR Part 131 that interpret part of the
CWA. Several revisions were made to the regulations related to designated uses, variances, and
antidegradation. We recommend that DWR evaluate these revisions during the triennial review. If
DWR identifies the need for changes, we would be happy to work with you to incorporate the desired
revisions into your WQS. In addition to the regulatory revisions mentioned above, 40 CFR Section
131.20(a) was amended as part of the 2015 WQS regulation revision. The amended regulation requires
tribes/states that choose not to adopt new or revised criteria for any parameters for which the EPA has
published new or updated criteria recommendations under CWA Section 304(a) to explain their
decision when reporting the results of their triennial review to the EPA. The goal of this revised
provision is to ensure public transparency about state WQS decisions. The EPA is including this item as
a reminder to include this information in any triennial review submittal to the EPA.

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Coordination

The EPA would like to continue coordination with the DWR during standards revisions and is
committed to providing any technical expertise requested by DWR in the future development and
revision of North Carolina’s water quality standards. The EPA encourages DWR to continue to work
early on with other agencies such as the U. S. Fish and Wildlife Service and National Marine Fisheries
Service as DWR develops draft water quality standards revisions. In addition, we encourage DWR to
work with the Eastern Band of Cherokee Indians and the Catawba Indian Nation (as appropriate) on
water quality standards issues of importance or significance that may affect their interests.

The above items cover the main topics for the upcoming triennial review; however, new items may
arise based on stakeholder interests or new or existing EPA guidance. We look forward to working
with and assisting you during this triennial review process. Should you have any questions, please
contact me at 404-562-9392 or Lauren Petter at 404-562-9272 or [e-mail].

Sincerely,

Stacey Bouma, Manager
Water Quality Branch
Water Division

cc: Christopher Ventaloro, NC DWR