CHAPTER 3 

Issue Category: Triennial Reviews

Pages 3-111 – 3-137

Response to Public Comments

Water Quality Standard Regulatory Revisions

August, 2015

40 CFR Part 131

Docket #: EPA-HQ-OQ-2010-0606

This document is part of a larger document.
Chapter 3 – Response Essays 6.a – Tri – Gen Supp 

Essay 6.a – Triennial Reviews: General Support

A. Support

The U.S. Environmental Protection Agency (EPA) appreciates and acknowledges the commenters 

expressing general support for EPA’s proposed change to section 131.20(a). In addition, EPA 

acknowledges commenters’ descriptions of their triennial review processes.

Some commenters supported EPA’s proposed language because they consider it to be consistent with 

the Clean Water Act (CWA) and reflective of the current practice of states and authorized tribes. EPA 

appreciates and acknowledges these commenters’ support. Several commenters who supported the 

proposed requirement requested that EPA retain “to assure that designated uses continue to be 

protected” language as proposed. However, in light of other comments received on the proposal, EPA 

edited the language as described in section II.C of the preamble to the final rule. Importantly, both Title 

40 of the Code of Federal Regulations (CFR) section131.5 and section 131.11 include the language these 

commenters wanted EPA to retain. As such, their interest is met as the regulation still requires that 

states and authorized tribes adopt “criteria that protect the designated uses.” EPA encourages 

commenters to evaluate their states’ or authorized tribes’ triennial review processes in light of the final 

rule requirements at section 131.20(a), as well as the discussion at section II.C in the preamble to the 

final rule. The final rule clarifies that states and authorized tribes must review at least once every three 

years their applicable water quality standards (WQS) (adopted into state or authorized tribal law 

pursuant to sections 131.10—131.15 as well as federally promulgated WQS), and also includes a 

requirement that if states and authorized tribes, following a triennial review, choose not to adopt new 

or revised criteria for any parameters for which EPA has published new or updated CWA section 304(a) 

criteria recommendations, they must explain their decision when reporting the results of their triennial 

review to EPA pursuant to CWA section 303(c)(1) and 40 CFR 131.20(c). The preamble to the final rule 

also describes that when states and authorized tribes conduct their next triennial review (following 

publication of the final rule), they must provide an explanation where the criterion in question is related 

to a parameter for which EPA has published CWA section 304(a) criteria recommendations since May 

30, 2000. During subsequent triennial reviews (i.e., after the initial review after this rule is finalized), 

states and authorized tribes must do the same for criteria related to parameters for which EPA has 

published CWA section 304(a) criteria recommendations since the states’ or authorized tribes’ most 

recent triennial review.

B. Other

With regard to commenters suggesting that EPA’s proposed rule does not require states or authorized 

tribes to actually adopt EPA’s CWA section 304(a) criteria recommendations, EPA agrees. Neither the 

proposed rule, nor the final rule, changes state and authorized tribal discretion to establish criteria 

pursuant to any of the approaches described in section 131.11(b). See also EPA’s response to code 6.e – 

Triennial Reviews: EPA 304(a) Criteria.

With regard to the commenters agreeing that WQS should be reviewed and modified based on sound 

science, EPA agrees. See also EPA’s responses to codes 6.e – Triennial Reviews: EPA 304(a) Criteria and 

6.g – Triennial Reviews: General Comments. 

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With regard to the comments related to the specific rule language proposed at section 131.20(a), see 

EPA’s response to code 6.f – Triennial Reviews: Proposed Revision.

Some commenters expressed support for the proposed revision as long as the regulation does not 

require every water body and every WQS to be reviewed every three years. The final rule does not 

affect states’ or authorized tribes’ discretion to identify high priority target areas during their triennial 

reviews. However, the CWA and the EPA’s implementing regulation require the state or authorized tribe 

to hold, at least once every three years, a public hearing on all applicable WQS, i.e., CWA-effective WQS 

that apply to state or tribal waters, not just a subset of applicable WQS that the state or tribe has 

identified as high priority. In this regard, states and authorized tribes must seek and consider public 

comment on all of their applicable WQS, including designated uses, water quality criteria, 

antidegradation requirements, WQS variances, compliance schedule authorizing provisions (CSAP), 

other general policies that constitute WQS, and any applicable, federally promulgated WQS. See also 

EPA’s response related to the scope of triennial review in code 6.g – Triennial Reviews: General

Comments. 

Some commenters expressed concern that the timeframe (three years) to conduct a triennial review of 

state and authorized tribal WQS is too short. EPA notes that this timeframe comes directly from CWA 

section 303(c)(1). EPA acknowledges the challenges (e.g., the legal and administrative processes, 

resource constraints) that states and authorized tribes may experience when conducting triennial 

reviews, however, EPA has no authority or discretion to provide a longer timeframe for triennial reviews 

in the regulation than the statute specifically allows. EPA’s rulemaking neither proposed nor finalized a 

change to the three-year timeframe for a triennial review. See also EPA’s response to code 6.g – 

Triennial Reviews: General Comments. 

With regard to commenters discussing specific issues with existing state-adopted criteria, this issue is 

outside the scope of this rulemaking because this rulemaking is not establishing WQS applicable to any 

state or tribal waters, rather it is modifying the overall WQS regulation under which states, authorized 

tribes, and EPA operate.

With regard to commenters suggesting that EPA strengthen the proposed requirement, see the final 

rule requirements at section 131.20(a), as well as the discussion at section II.C in the preamble to the 

final rule. 

With regard to commenters suggesting that EPA disapprove a state or authorized tribal WQS submission 

solely based on an insufficient record showing the state or authorized tribe properly considered new or 

updated CWA section 304(a) criteria recommendations, EPA disagrees. EPA does not have the authority 

to disapprove (or withhold action on) new or revised state or authorized tribal WQS that otherwise meet 

the requirements of the CWA. Absent the adoption or submission of a new or revised state or 

authorized tribal WQS, EPA has authority under CWA section 303(c)(4)(B) (and implementing regulation

at section 131.22(b)) to make an Administrator’s determination that new or revised WQS are necessary 

to meet the requirements of the Act. Once the Administrator has made such determination, EPA must 

promptly prepare and publish proposed regulations setting forth new or revised WQS for the waters of 

the United States involved, and must then promulgate such WQS, unless the state or authorized tribe 

adopts and the EPA approves such WQS before the EPA promulgation is finalized. In this regard, where 

the public has information emphasizing the need for certain criteria to be incorporated into a state’s or 

authorized tribe’s WQS, in addition to providing comment during the underlying state or authorized 

tribal notice and comment rulemaking process, the public may provide this information to EPA 

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Chapter 3 – Response Essays 6.a – Tri – Gen Supp 

(e.g., through a petition under section 553(e) of the Administrative Procedure Act (APA) (Title 5 of the 

U.S. Code (U.S.C.) Section 553(e)) to factor into the Agency’s consideration for and decision to make an

Administrator’s determination that new or revised WQS are necessary to meet the requirements of the 

CWA. 

With regard to the comments suggesting that states and authorized tribes have flexibility or discretion 

to respond to each of the public comments they receive during triennial review, EPA acknowledges the 

challenges and limitations that states and authorized tribes may experience when conducting triennial 

reviews. However, the public comments received during triennial review are part of the state’s or 

authorized tribe’s WQS review process, and states and authorized tribes must follow any and all public 

participation and administrative procedures required in state or tribal law with respect to this process, 

in addition to any federal requirements, including those in the final rule. States and authorized tribes 

must submit a certification from the state Attorney General or appropriate tribal legal authority stating 

that any new or revised WQS were duly adopted pursuant to state or tribal law, as well as the 

requirements under 131.20. EPA notes that it can and does also look at a state’s or authorized tribe’s 

rulemaking record, including the public hearing transcript and their responsiveness summary 

(i.e., response to comment document) when deciding whether to approve or disapprove a state or 

authorized tribe’s new or revised WQS. Where the public is dissatisfied with the response (or lack of)

related to a state’s or authorized tribe’s triennial review and/or the state’s or authorized tribe’s new or 

revised WQS, the public may pursue challenge of the state or authorized tribal action in state or tribal 

court or pursue legal challenge of EPA’s action in federal court. Further, where the public is dissatisfied 

with the response (or lack of) related to a state’s or authorized tribe’s existing (i.e., not new/revised) 

WQS, the public may petition EPA to promulgate a new/revised WQS under section 553(e) of the APA

(5 U.S.C. 553(e)), which could implicate EPA’s Administrator’s determination authority under CWA 

section 303(c)(4)(B).

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Chapter 3 – Response Essays 6.b – Tri – Gen Opp

Essay 6.b – Triennial Reviews: General Opposition

A. General Opposition

Some commenters opposed the U.S. Environmental Protection Agency’s (EPA’s) proposed change to 

section 131.20(a), but provided no further rationale for their opposition. Some commenters opposed 

EPA’s proposed language because they believe the existing language is sufficient. EPA disagrees. See 

EPA’s rationale for the final rule regarding triennial rules in section II.C of the preamble to the final rule.

In addition, to date, there has been confusion regarding what the entirety of section 131.20(a) means in 

regards to the scope of a triennial review, and there have been inconsistent interpretations of whether 

and how the EPA’s Clean Water Act (CWA) section 304(a) criteria recommendations play a role in

triennial review of state and authorized tribal water quality standards (WQS). Stakeholders have 

expressed concern that states and authorized tribes may retain criteria in their WQS that are no longer 

protective of designated uses for multiple triennial review cycles, despite the availability of new or 

updated CWA section 304(a) criteria recommendations. The final rule includes a requirement that if 

states and authorized tribes, following a triennial review, choose not to adopt new or revised criteria for 

any parameters for which EPA has published new or updated CWA section 304(a) criteria 

recommendations, they must explain their decision when reporting the results of their triennial review 

to EPA under CWA section 303(c)(1) and Title 40 of the Code of Federal Regulations (CFR) section 

131.20(c). This will ensure that, during triennial review, states and authorized tribes consider the latest 

science as reflected in the CWA section 304(a) criteria recommendations, and explain their decisions to 

EPA (and the public). Without such an explanation, EPA and the public may be led to believe that state 

or authorized tribe is disregarding public comments and environmental protection when really the state 

or authorized tribe has a plan based on different priorities that has not been communicated to EPA or 

the public. In regard to comments concerned with a state having to review their criteria outside of the 

triennial review process or as soon as EPA publishes new CWA section 304(a) criteria, see response 

essay 6.g – Triennial Reviews: General Comments. 

The confusion regarding the scope of a triennial review is illustrated in the public comments suggesting 

that EPA’s proposed change to section 131.20(a) expands the existing requirements for triennial review 

and creates a new duty or burden for states and authorized tribes in triennial review. Commenters 

argue that the existing regulation only requires states and authorized tribes to triennially review 

designated uses that do not include the uses specified in CWA section 101(a)(2) and that the change to 

section 131.20(a) added a new duty and burden on states and authorized tribes during their triennial 

review. EPA disagrees. These comments are based on an inaccurate reading of the regulation (and CWA 

section 303(c)(1)), as the first sentence of section 131.20(a) has always required states and authorized 

tribes to review “applicable water quality standards,” not only waterbody segments with WQS that do 

not include the uses specified in CWA section 101(a)(2). The final rule is not expanding the CWA 

requirement to review applicable WQS or adding a new requirement or burden; instead, the final rule

(and accompanying preamble) specifically outlines what is meant by the term “applicable” WQS and 

highlights the need to review existing water quality criteria when EPA has issued new or updated CWA 

section 304(a) criteria recommendations. The final rule clarifies that states and authorized tribes must 

review applicable WQS adopted into state or authorized tribal law pursuant to sections 131.10—131.15 

as well as federally promulgated WQS. Together, the triennial review provisions in the final rule clarify 

the triennial review requirements, specifying the role of new or updated CWA section 304(a) criteria 

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recommendations in the development of WQS by states and authorized tribes, promoting public 

transparency, and identifying the applicable WQS that must be reviewed triennially.

Also, EPA agrees with commenters that noted that the review of criteria under section 131.20(a) could 

lead to changes in criteria that are more or less stringent and, therefore, revised the proposed rule text 

to better reflect what is required and what could result in such cases. EPA partially agrees with 

commenters who were concerned the proposed wording of the provision gave the impression that CWA 

section 304(a) recommendations are “superior” to other criteria adopted by states and authorized tribes 

and approved by EPA. EPA’s recommendations are not “superior” to other criteria but they are based on 

the latest science and reflect years and significant amount of taxpayer dollars invested into researching 

what parameter levels may exist in surface waters without impairing the CWA section 101(a)(2) 

designated uses, and thus they do warrant specific and careful consideration by states and authorized 

tribes. Additionally, EPA does not desire CWA section 304(a) recommended criteria to be “de facto” 

state or authorized tribal standards, as some commenters suggested. Again, the requirement is simply 

to ensure that states and authorized tribes carefully review their existing criteria to ensure that they 

continue to protect applicable designated uses if and when EPA issues new or updated CWA section 

304(a) criteria recommendations. Based on those and other comments, EPA revised the regulatory text 

to place emphasis on the latest science (which is the real driver here) instead of a single focus on CWA 

section 304(a) recommendations (which is simply the vehicle by which the latest science is conveyed to 

the public). 

B. Rule Increases Public Transparency

With regard to the comments suggesting that any final changes to section 131.20(a) focus on increasing 

public understanding, EPA agrees. EPA’s final rule includes a requirement that if states and authorized 

tribes, following a triennial review, choose not to adopt new or revised criteria for any parameters for 

which EPA has published new or updated CWA section 304(a) criteria recommendations, they must 

explain their decision when reporting the results of their triennial review to EPA under CWA section 

303(c)(1) and 40 CFR 131.20(c). By requiring states and authorized tribes to provide an explanation as 

specified in the final rule, states and authorized tribes must communicate with EPA (and hence the 

public) about their decision-making process and any plans they may have to adopt or revise criteria for 

these parameters in the future. Without such an explanation, EPA and the public may be led to believe 

that the state or authorized tribe is disregarding public comments and environmental protection when 

really the state or authorized tribe has a plan based on different priorities that has not been 

communicated to EPA or the public.

C. Other

With regard to the comments claiming that EPA’s proposed change to section 131.20(a) would usurp the 

states’ and authorized tribes’ primacy to establish WQS, see EPA’s response to code 3.a – EPA’s Legal

Authority: General Comments. With regard to comments discussing whether a state’s or authorized 

tribe’s current process will meet the requirement at 131.20(a), see response to code 6.c – Triennial 

Reviews: Review Process.

With regard to the comments claiming that a complete review of the science behind the state 

designated use categories during a triennial review is a waste of limited state and authorized tribal 

resources with little or no environmental benefit, EPA disagrees. The CWA and EPA’s implementing 

regulation require states and authorized tribes to hold, at least once every three years, a public hearing 

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for the purpose of reviewing applicable WQS, which are all state or authorized tribal WQS as well as 

federally promulgated WQS and not just a subset of WQS that the state or authorized tribe has 

identified as high priority. EPA acknowledges that some states and authorized tribes target specific WQS 

during an individual triennial review to balance resources and priorities. While the final rule does not 

affect states’ or authorized tribes’ discretion to identify such priority areas for action, states and 

authorized tribes must still, at a minimum, seek and consider public comment on all applicable WQS

during triennial review (per the CWA requirement to do so). The final rule clarifies that when conducting 

triennial reviews, states and authorized tribes must review all applicable WQS adopted into state or 

tribal law pursuant to sections 131.10–131.15 and any federally promulgated WQS for that state or tribe 

(i.e., all applicable WQS). Applicable WQS include designated uses (section 131.10), water quality criteria 

(section 131.11), antidegradation provisions (section 131.12), general policies (where such policies 

constitute WQS) (section 131.13), WQS variances (section 131.14), and provisions authorizing the use of 

schedules of compliance for water quality-based effluent limits (WQBELs) in National Pollutant 

Discharge Elimination System (NPDES) permits (section 131.15). See also EPA’s response to codes 6.g – 

Triennial Reviews: General Comments, 12.a – Economics: General Comments and code 12.e – 

Economics: Benefits of Proposed Rule. 

For more information related to public participation during a state’s or authorized tribe’s triennial 

review and EPA’s proposed changes to section 131.20(b) related to public participation, see EPA’s 

response to code 6.d – Triennial Reviews: Public Meeting/Hearing.

With regard to the comments questioning the proposed rule language at section 131.20(a), see EPA’s 

response to code 6.f – Triennial Reviews: Proposed Revision.

With regard to the comments suggesting that the timeframe (three years) to conduct a triennial review 

of state and authorized tribal WQS is too short, EPA notes that this timeframe comes directly from

Congress and CWA section 303(c)(1). EPA acknowledges the challenges (e.g., the legal and 

administrative processes, resource constraints) that states and authorized tribes may experience when 

conducting triennial reviews, however, EPA has no authority to provide a longer timeframe for triennial 

reviews in the regulation than the statute allows. EPA’s rulemaking neither proposed nor finalized a 

change to the three-year timeframe for a triennial review. See also EPA’s response to code 6.g – 

Triennial Reviews: General Comments. 

With regard to the comments expressing concern that the proposed rule language at section 131.20(a) 

would require states and authorized tribes to adopt criteria that they have deemed “not necessary”, see 

EPA’s response related to the revision to section 131.2 in code 10.a – Other Changes to the Rule. 

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Chapter 3 – Response Essays 6.c – Tri – Review Process

Essay 6.c – Triennial Reviews: Review Process

The U.S. Environmental Protection Agency (EPA) appreciates and acknowledges commenters’ 

descriptions of state and authorized tribal triennial review processes. EPA also appreciates commenters’ 

support for the proposed triennial review provision (see response essay code 6.a – Triennial Reviews: 

General Support). EPA acknowledges commenters’ concerns that states and authorized tribes are not 

meeting the triennial review requirements and may be retaining inadequate water quality standards 

(WQS). In response to general comments on the triennial review process, see final rule requirements at 

section 131.20(a) and 131.20(b), as well as the discussion in sections II.C and II.G in the preamble to the 

final rule. The final rule, at section 131.20(a), clarifies that states’ and authorized tribes’ triennial reviews 

must include review of applicable WQS adopted into state or authorized tribal law pursuant to sections

131.10—131.15 as well as federally promulgated WQS for such state or tribe, and also includes a 

requirement that if states and authorized tribes, following a triennial review, choose not to adopt new 

or revised criteria for any parameters for which EPA has published new or updated Clean Water Act 

(CWA) section 304(a) criteria recommendations, they must explain their decision when reporting the 

results of their triennial review to EPA pursuant to CWA section 303(c)(1) and Title 40 of the Code of 

Federal Regulations (CFR) section 131.20(c). The final rule, at section 131.20(b), clarifies the public 

participation requirements when reviewing as well as when revising WQS. See also EPA’s response 

essays for codes 6.d – Triennial Reviews: Public Meeting/Hearing for additional discussion concerning 

public hearings, and 6.h – Triennial Reviews: EPA’s Legal Authority for a discussion on EPA’s authority 

related to triennial reviews. See response essay 6.g – Triennial Reviews: General Comments in regards 

to: (1) EPA’s oversight authority in triennial reviews and the scope of triennial reviews; (2) a state’s or 

authorized tribe’s ability to prioritize their review of their WQS; and (3) commenters’ specific concerns 

about existing state-adopted criteria or state triennial review processes. In addition, EPA disagrees with 

comments that the Agency is complicit in states’ approaches that do not open the entirety of the WQS 

for public review (see response essay for code 6.g – Triennial Reviews: General Comments for additional 

discussion).

With regard to a commenter’s request that EPA secure additional funding for states to sufficiently 

conduct triennial reviews, EPA acknowledges the challenges and resource constraints that states and 

authorized tribes may experience when conducting triennial reviews, however, EPA has no authority to 

provide additional funding for this activity (beyond the federal assistance authorized pursuant to CWA 

section 106 to states, territories, the District of Columbia, tribes and interstate agencies to establish and 

implement ongoing water pollution control programs).

With regard to commenters’ concerns that the proposed rule adds a new burden for states and 

authorized tribes during triennial review, see EPA’s response to code 6.b – Triennial Reviews: General 

Opposition.

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Chapter 3 – Response Essays 6.d – Tri – Public Meet/Hear

Essay 6.d – Triennial Reviews: Public Meeting/Hearing

A. General

The U.S. Environmental Protection Agency (EPA) appreciates the commenters that provided descriptions 

of their triennial review processes. EPA acknowledges that states and authorized tribes each have 

unique triennial review processes and that they experience different challenges and limitations when 

conducting triennial reviews. In this regard, EPA acknowledges that states and authorized tribes may 

have public participation requirements, including definitions of public hearing and public meeting, 

codified in their state or tribal law. This rulemaking is not intended to necessarily change states’ or 

authorized tribes’ public participation processes, as long as such processes meet minimum federal 

requirements. The requirement to hold hearings for the purposes of reviewing, and as appropriate, 

modifying and adopting water quality standards (WQS) comes directly from Clean Water Act (CWA) 

section 303(c)(1). EPA does not have authority to change such a requirement under the CWA via 

rulemaking. At a minimum, per section 131.20(b), states and authorized tribes are required to follow the 

provisions of state or tribal law and EPA’s public participation regulation at Title 40 of the Code of 

Federal Regulations (CFR) Part 25, including in holding a public hearing, any time that they review their 

applicable WQS or any time that they revise one or more of their applicable WQS. EPA’s public 

participation regulation, at 40 CFR section 25.5, sets minimum requirements for states and authorized 

tribes to publicize a public hearing at least 45 days prior to the date of the hearing; provide to the public 

reports, documents and data relevant to the discussion at the public hearing at least 30 days before the 

hearing; hold the hearing at times and places that facilitate attendance by the public; schedule 

witnesses in advance to allow maximum participation and adequate time; and prepare a transcript, 

recording or other complete record of the hearing proceedings. See 40 CFR section 25.5 for the 

complete list of federal public hearing requirements. The final rule does not prohibit states’ and 

authorized tribes’ discretion to gather public input using other formats, such as public meetings and 

webinars, in addition to fulfilling the applicable requirements for a public hearing and complying with 

any other applicable requirements of 40 CFR Part 25 (e.g., 40 CFR section 25.10), any time that they 

review or revise their WQS. 

EPA reiterates that the purpose of EPA’s proposed and final revision to section 131.20(b) is to provide 

consistency with the language of CWA section 303(c)(1) and section 131.20(a), not to create a 

requirement that states and authorized tribes must hold multiple hearings when reviewing or multiple 

hearings when revising WQS. Neither the proposed rule nor the final rule are changing the requirements 

or terms included in 40 CFR Part 25. EPA reiterates the importance of public input during triennial 

reviews and state and authorized tribal rulemakings. When a public hearing is held as required by 

40 CFR Part 131 in the context of state or authorized tribal review of its applicable WQS or revision of 

one or more WQS, the public hearing must comply with the requirements of 40 CFR section 25.5 (in 

addition to state or tribal law if state or tribal law is more stringent). In fact, EPA has revised the text in 

section 131.5 and has deleted section 131.10(e) to ensure the public hearing requirements are clear and 

that it is transparent that EPA’s review and approval or disapproval of new or revised WQS involves 

evaluating whether the state or authorized tribe has followed applicable legal procedures, including 

40 CFR Part 25, for revising or adopting (but not reviewing, since EPA does not approve or disapprove 

triennial review themselves) standards (see final rule and section II.G of the preamble to the final rule 

for discussion of these changes).

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With regard to the commenter requesting clarification about when a hearing is required, the final rule 

clarifies that a public hearing is required when both “reviewing as well as when revising” WQS (per CWA 

section 303(c)(1)). Thus, a hearing is required when (1) reviewing WQS per section 131.20(a); (2) when 

revising WQS as a result of reviewing WQS per section 131.20(a); and (3) when revising WQS not as a 

result of reviewing WQS per section 131.20(a). To be clear, “review WQS per § 131.20(a)” includes the 

state’s or authorized tribe’s request for input on “scoping” the triennial review (e.g., solicitation on 

suggested triennial review topics and/or ranking of the topics prior to actually selecting certain areas for 

adoption or revision). See subsection B of this essay for additional discussion on a state’s or authorized 

tribe’s ability to attempt to prioritize its review of WQS while still complying with the CWA requirement 

to review all “applicable” WQS at least once every three years. 

With regard to the commenters expressing concern that the proposed revisions to section 131.20(b) 

required multiple hearings when reviewing or multiple hearings when revising WQS, this was not EPA’s 

intent. The final rule uses the phrase ‘one or more’ to make clear that holding one public hearing when 

reviewing, or one public hearing when revising, WQS will satisfy the legal CWA requirement, although 

states and authorized tribes may choose to hold multiple hearings for each (i.e., reviewing and revising 

WQS). See also the final rule requirement at section 131.20(b) and section II.G in the preamble to the 

final rule.

B. Other

With regard to commenters expressing concern about how much time passes between triennial reviews 

for various states and authorized tribes, EPA notes that the CWA sets forth the three-year timeframe 

and thus EPA does not have the authority to extend the timeframe beyond three years. See also EPA’s 

response in code 6.g – Triennial Reviews: General Comments. States and authorized tribes must comply 

with this CWA requirement.

With regard to commenters describing state and authorized tribal triennial review processes that 

identify and conduct public participation on certain portions of their WQS but not others, the final rule 

does not affect states’ or authorized tribes’ discretion to attempt to identify high priority target areas

during triennial review. However, the CWA and the EPA’s implementing regulation require the state or 

authorized tribe to hold, at least once every three years, a public hearing on all “applicable” WQS, not 

just a subset of applicable WQS that the state or authorized tribe has identified as high priority. In other 

words, the state or authorized tribe can attempt to prioritize certain applicable WQS for review, but if a 

member of the public comments on another WQS that is applicable but not within the state’s or 

authorized tribe’s priorities, the state or authorized tribe cannot claim that such applicable WQS is 

outside the scope of its triennial review, and thus must review such WQS for possible addition or 

revision. See also EPA’s response in code 6.g – Triennial Reviews: General Comments. 

Some commenters suggested that the CWA provides EPA authority to require states and authorized 

tribes to submit the entirety of its triennial review process (e.g., public comments submitted to the state 

or authorized tribe during triennial review and their response) and that EPA has an obligation to review 

the final submission. EPA notes that its authority to approve or disapprove state or authorized tribal 

WQS only applies to such new or revised WQS, but that under 40 CFR section 131.20(c), states and 

authorized tribes must submit the results of their triennial review, any supporting analysis, the 

methodologies used for site-specific criteria development, any general policies applicable to WQS and 

any revisions of the standards to the EPA Regional Administrator for review and approval within 30 days 

of the final state or authorized tribal action to adopt and certify the revised standard, or if no revisions 

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are made as a result of the review, within 30 days of the completion of the review. See also EPA’s 

responses to codes 6.f – Triennial Reviews: Proposed Revision and 6.a – Triennial Reviews: General 

Support. 

C. Outside the Scope of This Rulemaking

With regard to the commenter requesting that EPA revise the definition of public hearing, neither EPA’s 

proposed rule nor the final rule contemplated revising this meaning of this term in 40 CFR Part 25. Thus, 

this issue is outside the scope of this rulemaking. EPA notes that 40 CFR Part 131 does not include a 

definition for public hearing, but instead includes a requirement for the state or authorized tribe to hold 

a public hearing consistent with 40 CFR Part 25. The comment requests changes to 40 CFR Part 25 to 

revise the definition to include virtual hearings and that EPA take into account “the current nature of the 

electronic era.” EPA notes that, as is obvious due to the timing of their promulgation, neither 40 CFR 

Part 131 nor 40 CFR Part 25 contemplated the electronic systems that are currently available today 

when establishing the requirements related to the location of the public hearing. Therefore, a virtual 

location for the public hearing is not prohibited by the current regulations, and could satisfy such 

requirements if done appropriately. EPA plans to provide future guidance on how to hold a virtual public

hearing that meets the requirements of 40 CFR section 25.5.

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Chapter 3 – Response Essays 6.e – Tri – EPA 304(a) Criteria

Essay 6.e – Triennial Reviews: EPA 304(a) Criteria

A. Concerns That Clean Water Act Section 304(a) Criteria Are Not Updated 

Consistently

Several commenters noted that the U.S. Environmental Protection Agency’s (EPA’s) Clean Water Act

(CWA) section 304(a) criteria recommendations are not updated by EPA on a regular basis and 

questioned why, then, EPA would require states and authorized tribes to examine criteria using CWA 

section 304(a) criteria recommendations. EPA disagrees with commenters that claimed that because the 

CWA section 304(a) criteria are not updated on a regular basis, this makes the proposed change at 

section 131.20(a) unreasonable. EPA acknowledges that some criteria have not been updated recently, 

however, the Agency continues to invest significant resources to examine evolving science for the 

purpose of updating existing and developing new CWA section 304(a) criteria recommendations to help 

states and authorized tribes meet the requirements of the Act, and wants to ensure that states and 

authorized tribes are considering such recommendations in deciding whether and how to update their 

water quality criteria. 

EPA has developed and published CWA section 304(a) criteria recommendations for approximately 

150 pollutants that are based on data and scientific judgments on pollutant concentrations and 

environmental or human health effects. EPA’s compilation of national water quality criteria 

recommendations, published pursuant to CWA section 304(a), can be found at: 

http://water.epa.gov/scitech/swguidance/standards/criteria/current/index.cfm. 

In response to comments, the final rule focuses on requiring states and authorized tribes to explain their

decisions to EPA (and the public) where they do not update their criteria after publication of new or 

updated recommendations from EPA. Since EPA updates its CWA section 304(a) recommendations 

periodically (per the statute, “from time to time”) to reflect the latest science, it is important that states 

and authorized tribes consider EPA’s new or updated recommendations and explain any decisions on 

their part to not revise or adopt criteria for parameters for which the EPA has published new or updated

CWA section 304(a) criteria recommendations. EPA reiterates that under the final rule, when states and 

authorized tribes conduct their next triennial review following publication of this rule, they must provide 

an explanation where the criterion in question is related to a parameter for which EPA has published 

CWA section 304(a) criteria recommendations since May 30, 2000 (which is the key date under the 

“Alaska Rule” at Title 40 of the Code of Federal Regulations (CFR) sections 131.21(c) and (e). During the 

triennial reviews that follow that initial review, states and authorized tribes must do the same for any 

and all criteria related to parameters for which EPA has published CWA section 304(a) criteria 

recommendations since the states’ or authorized tribes’ most recent triennial review. For discussion 

responding to concerns regarding the implications of increasing the administrative burden of continuous 

re-examination of criteria, see response to code 6.f – Triennial Reviews: Proposed Revision.

B. Clean Water Act Section 304(a) Criteria Recommendations Are Guidance

EPA agrees with commenters that stated that EPA’s CWA section 304(a) are only guidance. As discussed 

in section II.C in the preamble to the final rule, states and authorized tribes are not required to adopt 

EPA’s CWA section 304(a) criteria recommendations, but under this final regulatory provision, they must 

consider them and, if they do not adopt revised criteria, explain why they did not. When re-examining 

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existing state or authorized tribal criteria during a triennial review to determine if new or revised criteria 

must be adopted to protect designated uses, states and authorized tribes may use any of the 

approaches in section 131.11(b) to establish new or revised criteria: (1) using the CWA section 304(a) 

criteria guidance, (2) modifying the CWA section 304(a) criteria guidance to reflect site-specific 

conditions, or (3) using other scientifically defensible methods, so long as the resulting criteria meet 

CWA requirements in that they protect applicable designated uses and are based on sound science. EPA 

has addressed these comments by revising language in the final rule to place emphasis on the latest 

science, with the release of CWA section 304(a) recommended criteria as the prompt for considering the 

latest science. EPA disagrees with commenters that suggest any addition to the provision at section 

131.20(a) is unnecessary or unimportant. See section II.C in the preamble to the final rule for a 

discussion of why EPA considers this change to be necessary and important. EPA acknowledges that 

because the CWA section 304(a) criteria are national recommendations, site-specific physical and/or

chemical water body characteristics, varying sensitivities of local aquatic communities, or site-specific 

legally reserved rights may not be precisely reflected in the national recommendations, and thus it is 

possible that more or less stringent criteria may be necessary or allowable in certain cases. 

A commenter requested that EPA’s CWA section 304(a) criteria recommendation documents contain a 

clear statement that they are guidance and do not constitute requirements. EPA’s CWA section 304(a) 

criteria recommendation documents already typically include a disclaimer in the foreword of the 

document such as, “EPA's CWA section 304(a) recommended water quality criteria do not substitute for 

the CWA or regulations, nor are they regulations themselves. Thus, EPA's recommended criteria do not 

impose legally binding requirements. States and authorized tribes have the discretion to adopt, where 

appropriate, other scientifically defensible water quality criteria that differ from these 

recommendations.” See also response to code 6.g – Triennial Reviews: General Comments for a 

discussion regarding concerns of EPA’s approval/disapproval of a state’s or authorized tribe’s 

consideration of criteria during the triennial review.

C. States and Authorized Tribes Can Consider Other New or Updated Science in 

Their Triennial Reviews

EPA appreciates the commenter that noted that it is reasonable for EPA to require consideration of the 

CWA section 304(a) criteria recommendations as one factor when states and authorized tribes evaluate 

their existing water quality standards (WQS). EPA agrees and reiterates that the final rule does not 

prohibit the state or authorized tribe from also including other new or updated scientific evidence, apart 

from EPA’s new or updated CWA section 304(a) recommended criteria, in its triennial review. In fact, a 

state or authorized tribe may want to look at new site-specific information relative to certain water 

bodies, for example, in addition to new or updated CWA section 304(a) criteria recommendation when 

deciding whether to adopt new or revised WQS for such waters. EPA encourages states and authorized 

tribes to do so where such site-specific information is available, as it may lead to more tailored and 

appropriate criteria for the waters in question.

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With regard to the commenters that suggested that EPA make explicit that states and authorized tribes 

may take into consideration differing ecological, physical, and hydrological characteristics of water

bodies when establishing WQS, EPA agrees. EPA acknowledges that because the CWA section 304(a) 

criteria are national recommendations, site-specific physical and chemical water body characteristics, 

varying sensitivities of local aquatic communities, and/or site-specific legally reserved rights may not be 

precisely reflected in the national recommendations. EPA’s 304(a) criteria recommendations are 

developed to be representative of waters across the Nation and, as such, may not necessarily reflect the 

actual species composition and/or characteristics at a particular site. As described in subsection B of this 

response, the rule does not affect state and authorized tribal discretion to establish new or revised 

criteria under section 131.11(b), i.e., based on EPA’s 304(a) guidance, 304(a) guidance modified to 

reflect site-specific conditions, or other scientifically defensible methods that are protective of 

applicable designated uses and based on sound scientific rationale. See Chapter 3 of EPA’s online Water 

Quality Standards Handbook (http://www.epa.gov/wqshandbook) for information on the procedures 

EPA has developed for deriving site-specific criteria.

D. Authority to Triennially Review Federally Promulgated Water Quality 

Standards

With regard to the commenter suggesting EPA conduct a triennial review of federally promulgated WQS, 

EPA disagrees for the following reasons. The final rule clarifies, as the CWA and regulation already 

require, that the applicable WQS that states and authorized tribes must review triennially include any

and all WQS that the EPA has either approved or promulgated for a state or tribe (40 CFR Part 131, 

Subpart D). In this regard, states and authorized tribes must triennially review any federally promulgated 

WQS that are applicable to their waters. If, during a triennial review, the state or authorized tribe 

determines that the federally promulgated WQS no longer protect its waters, the state or authorized 

tribe should adopt new or revised WQS. If EPA approves such new or revised WQS, EPA would then 

withdraw the federally promulgated WQS because they would no longer be necessary to meet CWA 

requirements. 

E. Other

In response to the comments suggesting that overly stringent criteria should be reconsidered during 

triennial reviews and that EPA should clarify the rule in this regard, or comments that the current 

triennial review regulations are difficult to meet, or that discuss EPA’s oversight role in ensuring timely 

triennial reviews, see response to code 6.g – Triennial Reviews: General Comments. 

With regard to comments that were concerned that the proposed wording of section 131.20(a) gave the 

impression that CWA section 304(a) recommendations are “superior” to other criteria adopted by states 

and authorized tribes and approved by EPA, see response for code 6.b – Triennial Reviews: General 

Opposition.

With regard to comments that the proposed revision at section 131.20(a) will lead to increased litigation

and comments that suggested changes to the proposed regulatory text, see response for code 6.f – 

Triennial Reviews: Proposed Revision.

With regard to comments on how EPA has addressed CWA section 303(c)(2)(B), see response for code 

2.c – History of WQS Regulation and Program. 

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Essay 6.f – Triennial Reviews: Proposed Revision

A. Comments Related to Triennial Review Proposed Revision

The U.S. Environmental Protection Agency (EPA) acknowledges commenters’ suggested rule text at 

section 131.20(a). Some commenters suggested revising the language to replace the proposed phrase 

“to assure that designated uses continue to be protected” with other phrases, such as “to assure that 

designated uses are protected” or “to assure that designated uses are reasonably protected.” They 

suggested revising the language so that it does not imply that only those criteria that would be more 

stringent should be evaluated, since at times EPA has promulgated new 304(a) recommendations that 

demonstrate that less stringent criteria are protective of designated uses. Some commenters suggested 

removing the phrase “to assure that designated uses continue to be protected” from the proposed rule 

language so it does not presume that new or updated section 304(a) criteria are superior to criteria that 

were adopted by the state and approved by EPA. Some commenters suggested revising the language to 

clarify that any modifications to criteria resulting from the review would need to follow the State's 

process for adopting or revising water quality standards (WQS). Some commenters suggested revising 

the language to specify that states and authorized tribes shall reexamine their criteria in light of updated 

304(a) recommendations “taking into consideration the appropriate adaptation of such 

recommendations based on the relevant ecological, physical, and hydrological characteristics of the 

water subject to the criteria.” Those commenters were concerned that the proposed approach would 

limit states’ and authorized tribes’ flexibility to adopt criteria that differ from 304(a) recommendations. 

Some commenters had suggestions for improving the flow and clarity of the proposed language, without 

changing the requirements. EPA acknowledges these suggestions for wording revisions in 131.20(a), but 

has not incorporated them into the final rule. As explained in the preamble, the focus of this part of the 

final rule is on how a state or authorized tribe explains its decisions to EPA (and the public) rather than 

on how the state or authorized tribe conducts its review. For this reason, these particular suggestions 

are not relevant to the final rule requirement.

Some comments requested that the final rule at section 131.20(a) make explicit that states and 

authorized tribes are required to accept comment and undertake review of “all” WQS, rather than 

“applicable” WQS. EPA disagrees, because the word “applicable” refers to “all” of the WQS that are 

applicable in the relevant jurisdiction (WQS adopted by the state or tribe and approved by EPA as well as 

federally promulgated WQS.) Beyond that, there are no other WQS that are “applicable” for Clean 

Water Act (CWA) purposes. EPA’s intent in the proposal was not to qualify the initial sentence in section

131.20(a) regarding “applicable water quality standards” (which are all WQS either approved or 

promulgated by EPA for a state or tribe) but to supplement it by adding more detail regarding the 

triennial review of all existing criteria established pursuant to Title 40 of the Code of Federal Regulations

(CFR) section 131.11, and having the state or tribe explain why it did not update its criteria where EPA 

has issued updated 304(a) recommendations. The final rule clarifies what the regulation means by

“applicable water quality standards.”

For a discussion on how EPA chose to finalize the language of section 131.20(a) in response to 

comments, see the final rule requirements at section 131.20(a), as well as the discussion in section II.C in 

the preamble to the final rule.

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EPA acknowledges commenter’s descriptions of states’ and authorized tribes’ triennial review processes. 

EPA also encourages states and authorized tribes to evaluate their triennial review processes in light of 

the final rule requirements and preamble.

With regard to commenters suggesting that EPA’s proposed revision at section 131.20(a) would cause 

states and authorized tribes to consider whether the criterion could be attained now or in the future

prior to adopting new or revised criteria, EPA disagrees. Further, commenters suggest that the state or 

authorized tribe should do an attainability analysis (UAA) when considering whether to adopt new or 

updated criteria. EPA disagrees. The commenters misconstrue EPA’s intention with this revision. 

Designated uses establish the environmental objectives and management goals for a water body and by 

definition at 40 CFR 131.3(f) are “uses specified in WQS for each water body or segment, whether or not 

they are being attained.” A state or authorized tribe may designate a use that is not currently attained in 

a water body and, per 40 CFR 131.11(a), the state or authorized tribe would be required to adopt 

criteria sufficient to protect that designated use. Such criteria must be based on sound scientific 

rationale (not based on attainability). Where a water body is not attaining the designated use(s), the 

CWA and EPA’s regulations outline several tools (e.g., WQS variances, National Pollutant Discharge 

Elimination System (NPDES) permit compliance schedule (CS), total maximum daily loads (TMDLs)) that 

can be implemented such that the water body, over time, meets or attains the designated use goal.

With regard to the commenters suggesting that EPA revise section 131.22(b) to instead use its authority 

under CWA section 303(c)(4)(B) as an Administrator’s triennial review determination of each state’s and 

authorized tribe’s compliance, EPA disagrees. EPA notes that the CWA intends for, in fact, requires,

states and authorized tribes to perform the triennial review function. CWA section 303(c)(4)(B) outlines 

the Administrator’s authority, irrespective of a triennial review or submission of a revised or new WQS,

to determine that a new or revised WQS is necessary to meet the Act and to promptly propose and 

promulgate such WQS, unless the state or authorized tribe adopts a new or revised WQS the meets the 

requirements of the CWA first. With regard to comments providing suggestions on the regulatory text of 

section 131.20(b), see EPA’s response to code 6.d – Triennial Reviews: Public Meeting/Hearing.

Some commenters requested clarification about EPA’s recourse where a state or authorized tribe 

ignores the triennial review requirement, including whether EPA would withhold approval on submitted 

WQS in order to force review of other WQS. Other commenters urged EPA to use its authority under 

CWA section 303(c)(4)(B) to promulgate federal WQS for any state or authorized tribe that fails to 

conduct a triennial review, if such WQS are necessary to meet the requirements of the CWA. In 

response, EPA does not have the authority to disapprove (or withhold action on) a state or authorized 

tribal WQS submission that otherwise meets the requirements of the CWA in order to force review of 

other WQS. EPA notes that CWA section 303(c)(4) gives EPA authority to promptly prepare and publish 

new or revised WQS for the navigable waters involved in the case of inadequate new or revised WQS

(i.e., disapproved) under CWA section 303(c)(4)(A)), and in the case of inadequate WQS that are not new 

or revised (i.e., absent the adoption or submission of a new or revised state or authorized tribal WQS)

under CWA section 303(c)(4)(B). In response to the commenters, while EPA would not utilize the CWA 

section 303(c)(4)(B) authority solely because a state or authorized tribe has failed to conduct a triennial 

review, the EPA Administrator can use this authority to determine that new or revised WQS are 

necessary and promulgate such federal WQS for the navigable waters involved if state or authorized 

tribal WQS fail to meet CWA requirements. See also EPA’s response to codes 4.c — Administrator’s 

Determination: Specific Comments, 4.d — Administrator’s Determination: General Comments, and 6.g – 

Triennial Reviews: General Comments. 

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Some commenters questioned whether EPA would work with each state and authorized tribe to ensure 

that they are aware of the new or updated CWA section 304(a) criteria recommendations that have 

been published since the state’s or authorized tribe’s last triennial review. Generally speaking, yes. EPA 

encourages states and authorized tribes to work with EPA Regional Offices early and often, including 

when the state or authorized tribe is starting the triennial review process, to be sure they are aware of 

all relevant CWA requirements. In addition, EPA Headquarters intends to provide a list of priorities to 

EPA’s Regional Offices periodically. Such priorities would include a list of new and updated CWA section 

304(a) criteria recommendations that the EPA Regional Offices can use to coordinate with states and 

authorized tribes when starting a triennial review. Plus EPA’s CWA section 304(a) criteria 

recommendations are published in the Federal Register (FR) and listed on EPA’s website, making them 

easily accessible to all states and authorized tribes. See 

http://water.epa.gov/scitech/swguidance/standards/criteria/current/index.cfm. 

In response to comments concerning whether the review is needed when the state’s or tribe’s existing 

criteria are based on something other than EPA’s CWA section 304(a) recommendations, the answer is 

yes. EPA has clarified the language in the final rule that states and authorized tribes are required to 

provide an explanation when they do not adopt new or revised criteria for parameters for which EPA 

has published new or updated CWA section 304(a) criteria recommendations. The requirement is in 

effect regardless of the basis for the state’s or authorized tribe’s existing criteria.

B. Comments Related to the Scope of Triennial Review

EPA acknowledges the comments expressing support for the proposed rule because it clarifies that 

states and authorized tribes must reexamine criteria during triennial review to ensure that designated 

uses continue to be protected. See also EPA’s response to code 6.a – Triennial Reviews: General 

Support.

With regard to comments that EPA’s proposed rule added a new duty or burden for states and 

authorized tribes during triennial review and comments related to general opposition to the revisions to 

section 131.20(a), see EPA’s response to code 6.b – Triennial Reviews: General Opposition. 

See EPA’s response to code 6.g – Triennial Reviews: General Comments and section II.C in the preamble 

to the final rule for a discussion on what is the scope of WQS that are to be reviewed triennially, and for 

response to comments claiming that a complete review of the science behind the state designated use 

categories during a triennial review is a waste of limited state and authorized tribal resources with little 

or no environmental benefit (as well as above in this essay). See also EPA’s response to code 12.a – 

Economics: General Comments regarding EPA’s burden estimates. 

In addition, although neither CWA section 303(c) nor CWA section 304(a) requires states and authorized 

tribes to adopt criteria equal to newly published or updated EPA criteria recommendations, EPA notes 

that CWA section 303(c) does require states to establish ambient water quality criteria that protect 

applicable designated uses, including numeric criteria for priority toxic pollutants pursuant to CWA 

section 303(c)(2)(B). 

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C. Comments Related to the Triennial Review Process

Some commenters suggested that the CWA provides EPA the authority to require states and authorized 

tribes to submit the entirety of its triennial review process (e.g., public comments submitted to the state 

or authorized tribe during triennial review and their response) and all WQS for EPA review following 

each triennial review. See EPA’s response to code 6.g – Triennial Reviews: General Comments for a 

discussion on review of all WQS. Additionally, EPA does not have authority to review and take action on 

the supporting documentation (e.g., public comments and responses). However, EPA does consider this 

information when performing its review of new or revised WQS. CWA section 303(c) outlines the 

Agency’s authority and duty to approve or disapprove WQS; however, this authority only extends to 

new or revised state or authorized tribal WQS. See also EPA’s response in code 6.a – Triennial Reviews: 

General Support and EPA’s “What is a New or Revised Water Quality Standard Under CWA 303(c)(3) 

Frequently Asked Questions” (EPA-820-F-12-017, October 2012) 

(http://water.epa.gov/scitech/swguidance/standards/upload/cwa303faq.pdf). EPA notes that it can and 

does also look at a state’s or tribe’s rulemaking record, including the public hearing transcript and their 

responsiveness summary (i.e., response to comment document) when deciding whether to make an 

Administrator’s Determination that new or revised WQS are necessary under CWA section 303(c)(4)(B).

See also subsection A of this response for a discussion of EPA’s authority under CWA sections 

303(c)(4)(A) and (B).

With regard to comments related to public participation during a state’s or authorized tribe’s triennial 

review and EPA’s proposed changes to section 131.20(b) related to public participation, see EPA’s 

response to code 6.d – Triennial Reviews: Public Meeting/Hearing.

With regard to the comments that triennial review requirements apply regardless of whether states and 

authorized tribes intend to modify WQS to be more or less stringent, see EPA’s response to code 6.g – 

Triennial Reviews: General Comments. 

Some comments are related to the timeframe (three years) to conduct a triennial review and to the 

limitations that states and authorized tribes experience when conducting triennial review. EPA 

acknowledges the challenges (e.g., the legal and administrative processes, resource constraints) that 

states and authorized tribes may experience when conducting triennial reviews, and EPA notes that the 

three-year timeframe comes directly from Congress and CWA section 303(c)(1). See also EPA’s response 

to code 6.g – Triennial Reviews: General Comments. 

With regard to comments that states and authorized tribes have discretion about whether to modify or 

adopt WQS following a triennial review, EPA agrees. See EPA’s response to code 6.h – Triennial Reviews: 

EPA’s Legal Authority. 

With regard to comments that EPA approves or disapproves state and authorized tribal WQS as a whole

or entire set of WQS, EPA disagrees. As described above, the CWA requires EPA to approve or 

disapprove revised or new WQS, and thus does not require EPA to act on those WQS that are not 

revised or new. See also EPA’s response to code 6.h – Triennial Reviews: EPA’s Legal Authority. 

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D. Comments Related to Clean Water Act Section 304(a) Criteria and Triennial 

Review

See EPA’s response to code 6.e – Triennial Reviews: EPA 304(a) criteria with regard to comments that 

EPA’s CWA section 304(a) criteria recommendations are guidance and are not updated often enough, 

comments suggesting that EPA require states and authorized tribes to adopt new and updated CWA 

section 304(a) criteria recommendations within a certain period, such as four years, and for discussion 

of the role of EPA’s CWA section 304(a) recommendations (including use of site-specific information). 

Because the CWA is clear that section 304(a) criteria recommendations are guidance, EPA notes that 

commenters who suggest that the rule requires adoption of the new/revised CWA section 304(a) criteria 

recommendations into state or authorized tribal WQS misunderstood the proposed revision. See section 

II.C of the preamble to the final rule and section 131.20(a) for what is required under the final rule.

With regard to comments that claim the provision will lead to an increase in legal disputes and increased 

liability, EPA disagrees as EPA’s current regulations under section 131.11 continue to provide, as they 

have since 1983, for states and authorized tribes to adopt criteria that are protective of uses through 

several means, only one of which as discussed in EPA’s response to code 6.g – Triennial Reviews: 

General Comments. Also see EPA’s response to code 6.g – Triennial Reviews: General Comments, with 

regard to the comments about what an “adequate reexamination of criteria” is during triennial review

and comments on the need for EPA to specify/clarify how states have fulfilled this requirement. 

With regard to the comments suggesting that the requirement to re-examine criteria in light of new or 

updated CWA section 304(a) recommendations would be triggered at the publication of each new or 

updated CWA section 304(a) criteria recommendation (rather than during the next triennial review), 

EPA disagrees. See section II.C of the preamble for the final rule and EPA’s response to code 6.g – 

Triennial Reviews: General Comments. 

E. Other

With regard to the comments claiming that EPA’s proposed change to section 131.20(a) would usurp the 

states’ and authorized tribes’ primacy to establish WQS, see EPA’s response to code 3.a – EPA’s Legal

Authority: General Comments. 

With regard to comments related to costs and burden incurred by states and authorized tribes as a 

result of the proposed revision to triennial review or the burden incurred to justify a decision to not 

modify state or tribal criteria when EPA has issued new or updated CWA section 304(a) 

recommendations, see EPA’s response to code 12.a – Economics: General Comments and the Economic 

Analysis (EA) for the final rule. 

With regard to the comments expressing concern that the proposed rule language at section 131.20(a) 

would require states and authorized tribes to adopt criteria that they have deemed “not necessary”, see 

EPA’s response related to the revision to section 131.2 in code 10.a: Other Changes to the Rule. 

With regard to the comments related to highest attainable use (HAU), see EPA’s response to code 5.e – 

Designated Uses: Definitions/Terms. 

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With regard to the comments that suggested revising section 131.20(c) to include a requirement that 

the State shall include “any public comment received” in its submission of its triennial review to EPA, 

EPA notes that neither EPA’s proposed rule nor the final rule include changes to this section. EPA does 

not have authority to review and take action on the supporting documentation (e.g., public comments 

and responses). However, states typically include this information with their WQS submissions, or make 

it otherwise available to EPA, and EPA considers this information when performing its review of new or 

revised WQS. CWA section 303(c) outlines the Agency’s authority and duty to approve or disapprove 

WQS; however, this authority only extends to new or revised state or authorized tribal WQS. See also 

EPA’s response in code 6.a – Triennial Reviews: General Support and EPA’s “What is a New or Revised 

Water Quality Standard Under CWA 303(c)(3) Frequently Asked Questions” (EPA-820-F-12-017, October 

2012) (http://water.epa.gov/scitech/swguidance/standards/upload/cwa303faq.pdf). EPA notes that it 

can and does also look at a state’s or tribe’s rulemaking record, including the public hearing transcript 

and their responsiveness summary (i.e., response to comment document) when deciding whether to 

make an Administrator’s Determination that new or revised WQS are necessary under CWA section 

303(c)(4)(B). See also subsection A of this response for a discussion of EPA’s authority under CWA 

sections 303(c)(4)(A) and (B).

With regard to the commenters noting the statutory (CWA section 303(c)(3)) and regulatory (40 CFR 

131.21) requirements for EPA to either approve or disapprove a state’s or authorized tribe’s submission 

of new or revised WQS, neither EPA’s proposed rule nor the final rule include changes to this 

requirement. Therefore, this comment is outside the scope of this rulemaking, but EPA notes that its 

duty and authority to act on state or authorized tribal revised or new WQS remains unchanged due to 

this final rule. The commenter also refers to CWA section 303(a)(3)(C), however, there are no changes or 

interpretations to the 40 CFR Part 131 regulations related to this CWA section; therefore, this comment 

is outside the scope of this rulemaking.

With regard to the comments related to existing uses and antidegradation Tier 1, neither EPA’s

proposed rule nor the final rule include changes to these regulatory provisions. Therefore, these

comments are outside the scope of this rulemaking, and EPA notes that those requirements remain 

unchanged. 

With regard to the comments asserting that EPA purposefully omitted reference and discussion of CWA 

section 303(c)(2)(B) from this rulemaking, EPA disagrees. See EPA’s response to code 2.c for additional 

discussion. Additionally, although CWA 303(c)(2)(B) requires states to “adopt criteria for all toxic 

pollutants listed ... for which criteria have been published under 304(a)... as necessary to support such 

designated uses[,]” neither the Act nor EPA’s regulations require the adoption of the particular numeric 

value that EPA recommends in its CWA 304(a) criteria recommendation. Absent extenuating 

circumstances (such as requirements based on the Endangered Species Act or tribal treaty rights), states 

and authorized tribes can use any of the methods described 40 CFR 131.11(b) to develop numeric 

criteria for those toxic pollutants. 

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Chapter 3 – Response Essays 6.g – Tri – Other General

Essay 6.g – Triennial Reviews: General Comments

In addition to the responses below, see the final rule requirements at section 131.20(a) and section

131.20(b), as well as the discussion at sections II.C and II.G in the preamble to the final rule. See the 

U.S. Environmental Protection Agency’s (EPA’s) response to code 6.f – Triennial Reviews: Proposed 

Revision for the response related to specific suggested edits to the proposed regulatory text.

A. EPA Does Not Have Authority to Extend the Timeframe for Triennial Review

Several commenters suggested that EPA extend the timeframe beyond three years for states and 

authorized tribes to periodically review their applicable water quality standards (WQS). Although the 

EPA acknowledges the challenges (e.g., the legal and administrative processes, resource constraints) 

that states and authorized tribes may experience when conducting triennial reviews, the three-year 

timeframe for triennial review comes directly from Clean Water Act (CWA) section 303(c)(1). EPA has no 

authority to provide a longer timeframe for triennial reviews because this timeframe may only be 

extended by Congress through an amendment to the statute.

B. Scope of Triennial Review

With regard to the comments related to the scope of WQS to be reviewed during a triennial review, EPA 

acknowledges that each state and authorized tribe conducts their triennial review process differently.

The final rule clarifies that the “applicable” WQS to be reviewed triennially specifically include 

designated uses (section 131.10), water quality criteria (section 131.11), antidegradation requirements

(section 131.12), general policies (that constitute WQS) (section 131.13), WQS variances (section

131.14), provisions authorizing the use of schedules of compliance for water quality-based effluent 

limits (WQBELs) in National Pollutant Discharge Elimination System (NPDES) permits (section 131.15), 

and any federally promulgated WQS for such state or authorized tribe. EPA is aware of some states and 

authorized tribes that target specific WQS during an individual triennial review, in order to balance 

resources and priorities. The final rule does not affect such states’ or authorized tribes’ discretion to

attempt to identify high priority target areas. However, the CWA and the EPA’s implementing regulation 

require the state or authorized tribe to hold, at least once every three years, a public hearing on all 

“applicable” WQS, not just a subset of WQS that the state or authorized tribe has identified as high 

priority. In this regard, states and authorized tribes must seek and consider public input on all of their 

applicable WQS at least once every three years, which applicable WQS include designated uses, water 

quality criteria, antidegradation requirements, WQS variances, compliance schedule authorizing 

provisions (CSAPs), other general policies (that constitute WQS), and any applicable, federally

promulgated WQS for such state or authorized tribe. See also EPA’s response to code 6.f – Triennial 

Reviews: Proposed Revision with regard to comments suggesting that the proposed requirement at 

section 131.20(a) is a new/additional burden during the triennial review and with regard to comments 

requesting/suggesting the regulations require the submittal of a state’s or authorized tribe’s entire 

rulemaking record to EPA.

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C. Clean Water Act Section 304(a) Criteria Recommendations Are Guidance

With regard to the comments stating that EPA’s CWA section 304(a) criteria recommendations are 

guidance and national in scope, EPA agrees. EPA has developed and published CWA section 304(a) 

criteria recommendations for approximately 150 pollutants that are based on data and scientific 

judgments on pollutant concentrations and environmental or human health effects. The EPA’s 

compilation of national water quality criteria recommendations, published pursuant to CWA section 

304(a), can be found at: 

http://water.epa.gov/scitech/swguidance/standards/criteria/current/index.cfm. EPA acknowledges that 

because the CWA section 304(a) criteria are national recommendations, site-specific physical and 

chemical water body characteristics or varying sensitivities of local aquatic communities may not be 

precisely reflected in the national recommendations. As such, when re-examining existing criteria during 

a triennial review to determine if new or revised criteria are needed to protect designated uses, states 

and authorized tribes may consider any of the approaches in section 131.11(b) for establishing new or 

revised criteria: using the CWA section 304(a) criteria guidance, modifying the CWA section 304(a) 

criteria guidance to reflect site-specific conditions, or using other scientifically defensible methods. This

rulemaking is not intended to affect state and authorized tribal discretion to determine which approach 

to consider and/or follow (if the state or authorized tribe moves forward to adopt revised criteria) under

section 131.11(b). EPA acknowledges the state-specific examples related to development of site-specific 

criteria, and notes that the breadth of the various methods at section 131.11(b) would accommodate 

such examples. See also EPA’s response to code 6.e – Triennial Reviews: EPA 304(a) Criteria.

With regard to commenters requesting that EPA develop protocols for adapting criteria to specific water 

types, such as ephemeral and intermittent water bodies, EPA acknowledges the comments, but this 

issue is outside the scope of this rulemaking. EPA notes for the commenter that, in April 2013, the EPA 

published the Revised Deletion Process for the Site-Specific Recalculation Procedure for Aquatic Life 

Criteria, which provides guidance about editing the composition of a Species Sensitivity Distribution of 

tested species used to derive a site-specific aquatic life criterion in order to allow it to better reflect the 

taxonomy of species that reside at the site (See 

http://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/ammonia/upload/Revised-DeletionProcess-for-the-Site-Specific-Recalculation-Procedure-for-Aquatic-Life-Criteria.pdf). EPA also 

acknowledges the comments suggesting that EPA’s CWA section 304(a) criteria recommendations 

should consider cost-effectiveness. EPA disagrees because CWA section 304(a) sets out the basis for 

developing those recommendations (e.g., data and scientific judgments) and does not include cost 

considerations. EPA notes, in addition, that this issue is outside the scope of this rulemaking.

With regard to comments that EPA does not consistently publish new or updated CWA section 304(a) 

criteria recommendations, see EPA’s response to code 6.e – Triennial Reviews: EPA 304(a) Criteria.

D. EPA’s Oversight Authority

Some commenters suggested that EPA add regulatory language stating that the Agency will use its 

authority under CWA section 303(c)(4)(B) where states and authorized tribes fail to conduct triennial 

reviews. EPA acknowledges the state-specific examples to demonstrate that some states are failing to 

conduct or complete their triennial review processes on a timely basis. While EPA agrees that the CWA 

section 303(c)(4)(B) authority is important to ensure WQS meet the requirements of the CWA, EPA 

disagrees that the Agency needs to add this type of language in the context of failing to conduct or 

complete a triennial review on a timely basis. This is because EPA already has such authority clearly 

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spelled out in the CWA and implementation regulations, and may exercise it as appropriate, which very 

well could include a situation where a state or authorized tribe fails to conduct or complete a triennial 

review on a timely basis, and as a result has applicable WQS on its books that do not meet CWA 

requirements. 

EPA also disagrees with the commenter that suggests EPA add final rule language that after three years 

of failing to reexamine criteria, states and authorized tribes will be subject to federal promulgation.

Again, CWA section 303(c)(4)(B) (and EPA’s implementing regulation at section 131.22(b)) already give 

EPA the authority to determine, absent the adoption or submission of a new or revised state or 

authorized tribal WQS, that new or revised WQS are necessary to meet the requirements of the Act. 

Where a state or authorized tribe fails to review and revise WQS as necessary, the Administrator may 

make a determination, under CWA section 303(c)(4)(B), that new or revised WQS are necessary to meet 

the requirements of the CWA. Once the Administrator has made such determination, EPA must 

promptly prepare and publish proposed regulations setting forth new or revised WQS for the waters of 

the United States involved, and must then promulgate such WQS, unless the state or authorized tribe 

adopts and the EPA approves such WQS before the EPA promulgation.

With regard to the comments suggesting that EPA refuse to approve new or revised WQS from a state or 

authorized tribe until that state or authorized tribe modifies its criteria in light of new or updated CWA 

section 304(a) criteria recommendations, EPA disagrees. EPA does not have the authority to disapprove 

(or withhold action on) a state or authorized tribal WQS submission that otherwise meets the 

requirements of the CWA because of separate state or authorized tribal action or inaction that does not 

comply with separate requirements of the Act. 

EPA disagrees with comments suggesting that the Agency is complicit or is enabling states and 

authorized tribes to ignore the triennial review requirement. EPA’s regional offices frequently provide 

informal and formal comment to states and authorized tribes regarding both the timeliness and the 

content of their triennial reviews. In addition, EPA provides federal assistance, under CWA section 106, 

to states, territories, the District of Columbia, and tribes to establish and implement ongoing water 

pollution control programs—which can includes activities to conduct adequate triennial reviews. See 

also EPA’s response to code 6.f – Triennial Reviews: Proposed Revision for additional discussion on EPA’s 

use of its authority under CWA section 303(c)(4)(B).

E. Triennial Review Requirements Apply Regardless of Whether the Revised 

Water Quality Standards Are Becoming More or Less Stringent

With regard to the comments requesting clarification that the triennial review requirements apply 

regardless of whether the state or authorized tribe is revising WQS to be more stringent or less 

stringent, EPA agrees. As explained in the preamble to the final rule and clarified in section 131.20(a), 

during a triennial review, states and authorized tribes must seek and consider public comment on all of 

their applicable WQS, including designated uses, water quality criteria, antidegradation requirements, 

WQS variances, CSAPs, other general policies (that constitute WQS), and if applicable, federally

promulgated WQS, regardless of the direction of any proposed change to any WQS. If during a triennial 

review, for example, a state or authorized tribe finds information indicating that a use higher (i.e., better

or more stringent) than what is currently designated is attainable, the state or authorized tribe should 

revise their WQS to reflect this (and must do so if the higher/better use is a CWA section 101(a)(2) use). 

Similarly, if a state or authorized tribe finds information indicating that a CWA section 101(a)(2) use that 

was previously attainable is now unattainable, the state or authorized tribe could conduct a use 

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attainability analysis (UAA) per section 131.10(g) to determine the highest attainable use (HAU) and 

adopt it into their WQS in place of the unattainable use (the state or authorized tribe does not have to 

remove the unattainable use but could do so if demonstrated). EPA acknowledges that states and 

authorized tribes continue to have discretion to decide whether and how to modify or adopt new or 

revised WQS, as long as such WQS meet the minimum requirements of the CWA. With regard to today’s 

final rule requirement, it is important to note that, regardless of whether new or updated CWA section 

304(a) criteria recommendations are more stringent or less stringent than their predecessors or the 

state’s or authorized tribe’s existing criteria, today’s rule requires a state or authorized tribe to provide 

an explanation to EPA if it does not adopt new or revised criteria for those parameters/pollutants in its

next triennial review. Although EPA revised the regulatory text of section 131.20(a) in the final rule, EPA 

did not choose to make this point regarding stringency explicit in section 131.20(a) as section 131.11(b)

already makes clear that state and authorized tribal criteria can be more or less stringent than EPA’s 

CWA section 304(a) recommendations so long as the criteria protect the designated use and are based 

on sound scientific rationale. 

F. Examination of Criteria 

Some commenters requested clarification on what EPA considers adequate re-examination of criteria 

and on what EPA expects when a state or authorized tribe reexamines its criteria, but does not modify 

its WQS. The final rule requires that when submitting the results of its triennial review per the current 

requirements at section 131.20(c), the state or authorized tribe must provide an explanation if it chose 

not to adopt new or revised criteria for any parameters for which EPA has published new or updated 

CWA section 304(a) criteria recommendations. It is important to note that such explanation will not be 

reviewed and approved or disapproved by EPA pursuant to CWA section 303(c) and will not be used to 

disapprove a WQS submission that otherwise meets the requirements of the CWA. Rather, by requiring 

states and authorized tribes to provide an explanation as specified in the final rule, states and 

authorized tribes will have to communicate with EPA (and their public) about their decision-making 

process and any plans they may have to adopt or revise these criteria in the future. Without such an 

explanation, EPA and the public may be led to believe that the state or authorized tribe is disregarding 

the latest science, public comments, and environmental protection when really the state or authorized 

tribe has another plan based on different priorities that has not been communicated to the EPA or the 

public (such as being in the process of developing site-specific criteria for such state or authorized tribe 

instead of adopting EPA’s national recommendation). Further, such an explanation will help inform EPA 

and specifically the Administrator about whether a determination that new or revised WQS are 

necessary to meet the requirements of the CWA (and promulgation of federal WQS) is warranted. There 

is no minimum length or depth that such explanation should satisfy, but rather a reasonableness 

standard, i.e., EPA (and the public) will consider such explanation to see whether the state or authorized 

tribe has provided a reasonable explanation for not updating its existing criteria despite the existence of 

new or updated CWA section 304(a) recommendations. EPA would then evaluate such explanation in 

deciding whether to either make a CWA section 303(c)(4)(B) Administrator’s determination regarding 

whether new or revised WQS are necessary for such state or authorized tribe to meet the requirements 

of the CWA or respond affirmatively to a petition requesting such determination. With regard to 

comments that the proposed revision to section 131.20(a) will lead to increased litigation, see EPA’s 

response to code 6.f – Triennial Reviews: Proposed Revision.

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G. States and Authorized Tribes Can Consider Other New or Updated Science in 

Their Triennial Reviews

With regard to the comment suggesting that re-examination of criteria during a triennial review also 

includes consideration of other new or updated scientific evidence, not just CWA section 304(a) criteria 

recommendations, EPA agrees in part. Today’s final rule requires the state or authorized tribe to provide 

an explanation, following a triennial review, if it chose not to adopt new or revised criteria for any 

parameters for which EPA has published new or updated CWA section 304(a) criteria recommendations

(see also section II.C of the preamble to the final rule and the final regulatory text at section 131.20(a)). 

This requirement does not prohibit the state or authorized tribe from also including and evaluating

other new or updated scientific evidence in its re-examination. In fact, a state or authorized tribe may 

prefer to look at new site-specific information, for example, in addition to a new CWA section 304(a) 

criteria recommendation when deciding whether to adopt new or revised WQS. However, the 

requirement to submit an explanation to EPA is only triggered if the state or authorized tribe chose not 

to adopt new or revised criteria for any parameters for which EPA has published new or updated CWA 

section 304(a) criteria recommendations. Such explanation would not be required if the state or 

authorized tribe chose not to adopt new or revised criteria based on other new or updated scientific 

evidence (i.e., where EPA had not published new or updated CWA section 304(a) recommended criteria 

since the state’s or authorized tribe’s last triennial review). EPA also notes that CWA section 304(a) 

provides EPA the authority to develop and publish both “criteria for water quality accurately reflecting 

the latest scientific knowledge” (CWA section 304(a)(1)) and “information” (CWA section 304(a)(2)). The 

final rule requirement at section 131.20(a) to provide an explanation is related to the criteria published 

pursuant to CWA section 304(a)(1), but is not triggered by information published pursuant to CWA 

section 304(a)(2). See section II.C for additional discussion on why EPA choose to focus the review on 

those parameters for which EPA has new or updated CWA section 304(a) criteria.

H. The Final Rule Requirements to Consider Clean Water Act Section 304(a) 

Criteria Recommendations Apply at the Time of States’ and Authorized Tribes’ 

Triennial Review, Not at the Time of Publication of New or Updated Clean 

Water Act Section 304(a) Criteria Recommendations

With regard to the comment requesting clarification that re-examination of criteria in light of new or 

updated CWA section 304(a) recommendations is required in the context of the triennial review process, 

but not more frequently, EPA agrees that the re-examination requirement in the final rule is triggered 

during the triennial review process, not more frequently, such as at the time of publication of each new 

or updated CWA section 304(a) criteria recommendation. As described in section II.C in the preamble to 

the final rule, when states and authorized tribes conduct their next triennial review after this final rule 

takes effect, they must provide an explanation where the criterion in question is related to a parameter 

for which EPA has published CWA section 304(a) criteria recommendations since May 30, 2000 (the key 

date in EPA’s Alaska Rule at Title 40 of the Code of Federal Regulations (CFR) section 131.21(c) and (e)). 

During the triennial reviews that follow, states and authorized tribes must do the same for criteria 

related to parameters for which EPA has published CWA section 304(a) criteria recommendations since 

the states’ or authorized tribes’ most recent triennial review.

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I. Consideration of Input from Tribal Governments

Some commenters requested EPA require states to specifically seek and consider input from tribal 

governments and to ensure that affected tribes are properly consulted during state WQS rulemaking 

processes. Further, some commenters suggested EPA add language requiring consultation with affected 

tribes prior to any decision by EPA. Neither the proposed rule nor today’s final rule includes language 

requiring states to consider input from tribal governments or requiring tribal consultation on state 

triennial review processes by EPA, thus this issue is outside the scope of this rulemaking. That said, the 

Agency acknowledges the United States’ government-to-government relationship with and trust 

responsibility to federally recognized Indian tribes, and that EPA must ensure its actions do not conflict 

with tribal treaty rights. The Agency remains fully committed to engaging tribes as sovereign 

governments with a right to self-governance. Further, EPA acknowledges that when we have discretion, 

EPA programs should be implemented to honor and respect tribes. Good governance demands that EPA 

increase our efforts to work in concert with other federal agencies, tribes, states, and local governments 

to protect human health and the environment. Coming together to set priorities and define mutual roles 

and responsibilities regarding the administration of environmental protection programs will build 

stronger, more efficient and effective partnerships. EPA remains committed to continue building on the 

following efforts: engaging tribal-elected officials on key environmental and public-health issues through 

an annual tribal leaders’ listening session; coordinating with the Environmental Council of the States to 

include tribal governments in key discussions as co-regulators; using the Council for the Commission for 

Environmental Cooperation to ensure that the U.S., Canada and Mexico continue to work with 

indigenous communities across North America and recognize the importance of the traditional 

ecological knowledge and practices of indigenous communities; and working with the Department of the 

Interior to build tribal resiliency regarding the impacts of climate change.

J. Other

With regard to the comments suggesting the CWA provides EPA authority to require states and 

authorized tribes to submit the entirety of its triennial review process (e.g., public comments submitted 

to the state or authorized tribe during triennial review and responses to those comments), see EPA’s 

response in code 6.f – Triennial Reviews: Proposed Revision. 

With regard to comments related to public participation and when public hearings are required, see 

EPA’s response to code 6.d – Triennial Reviews: Public Meeting/Hearing.

With regard to commenters expressing specific concerns with existing state-adopted criteria, this issue is 

outside the scope of this rulemaking because this rulemaking is not establishing WQS applicable to any 

state or tribal waters. 

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Essay 6.h – Triennial Reviews: EPA’s Legal Authority

The U.S. Environmental Protection Agency (EPA) appreciates and acknowledges the commenters 

agreeing that states’ and authorized tribes’ triennial review includes reviewing all applicable water 

quality criteria, as well as all other applicable water quality standards (WQS). See also the final rule 

requirements at section 131.20(a), as well as the discussion at section II.C in the preamble to the final 

rule. The final rule clarifies that states and authorized tribes must review applicable WQS adopted into 

state or authorized tribal law pursuant to sections 131.10—131.15 as well as federally promulgated 

WQS at least once every three years, and also includes a requirement that if states and authorized 

tribes, following a triennial review, choose not to adopt new or revised criteria for any parameters for 

which EPA has published new or updated Clean Water Act (CWA) section 304(a) criteria 

recommendations since their last triennial review (except for their first triennial review following the 

effective date of this rule, which reaches back to any and all CWA section 304(a) criteria 

recommendations EPA has published new or updated since May 30, 2000), they must explain their 

decision when reporting the results of their triennial review to EPA pursuant to CWA section 303(c)(1) 

and Title 40 of the Code of Federal Regulations (CFR) section 131.20(c). EPA has provided a list of the 

CWA section 304(a) criteria recommendations that have been published (new or updated) since May 30, 

2000 in the docket for this rulemaking and posted this list on its website.

With regard to the comments urging EPA to use its authority to ensure states and authorized tribes 

conduct and complete triennial reviews of their WQS every three years, see EPA’s response to code 

6.g – Triennial Reviews: General Comments and to code 6.f – Triennial Reviews: Proposed Revision for 

discussions on EPA’s oversight authority. 

With regard to the comment that the CWA gives EPA the authority and obligation to review and approve 

or disapprove new or revised state or authorized tribal WQS, EPA agrees. CWA section 303(c)(2)(A) 

requires that states and authorize tribes submit new and revised WQS to EPA. Further, CWA section 

303(c)(3) requires that EPA either approve the new or revised WQS within sixty days of submission or 

disapprove within ninety days. If EPA disapproves a state’s or authorized tribe’s new or revised WQS, 

EPA would specify the changes necessary to meet the CWA and regulatory requirements. If the state or 

authorized tribe fails to adopt and submit necessary revisions within ninety days after notification of the 

disapproval, EPA must promptly propose and promulgate federal WQS as specified in CWA section 

303(c)(4)(A) and 40 CFR 131.22(a) (unless the state or authorized tribe revises and EPA approves before 

federal promulgation). 

With regard to the comments suggesting that EPA has authority to require states and authorized tribes 

to adopt criteria, EPA disagrees in part and agrees in part. Under the final rule, states and authorized 

tribes are not required to adopt EPA’s CWA section 304(a) recommendations, and are instead, where 

they are not adopting new or revised criteria for those parameters which EPA has published new or 

revised CWA section 304(a) recommendations, required to provide an explanation for why they are not 

revising their criteria for parameters that correspond to EPA’s new or updated recommendations at this 

time. However, states and authorized tribes must adopt criteria that are scientifically defensible and 

protective of the designated use to ensure that WQS “protect the public health or welfare, enhance the 

quality of water and serve the purposes of” the Act (CWA section 303(c)(2)(A)) and to adopt criteria for 

the toxic pollutant parameters as described in CWA 303(c)(2)(B) and section 131.11.

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In regards to EPA’s role, the CWA creates a partnership between states and authorized tribes and EPA, 

by assigning states and authorized tribes the primary role of adopting WQS (CWA sections 101(b) and 

303), and EPA the oversight role of reviewing and approving or disapproving state and authorized tribal 

WQS and promulgating federal WQS as necessary (CWA section 303(c)). The CWA also assigns EPA the 

role of publishing national recommended criteria to assist states and authorized tribes in adopting water 

quality criteria in their WQS (CWA section 304(a)(1)). This rulemaking did not propose and is not 

finalizing changes to the substance of section 131.11, which, at bottom, requires that state and 

authorized tribes adopt criteria that protect applicable designated uses and are based on sound 

scientific rationale (regardless of whether those criteria are less stringent than, equal to, or more 

stringent than EPA’s CWA section 304(a) recommendations). EPA acknowledges that where a state or 

authorized tribe fails to review and revise WQS where necessary, the Administrator may make a

determination that new or revised WQS are necessary to meet the requirements of the CWA, under 

CWA section 303(c)(4)(B). See also EPA’s response related to EPA’s oversight authority in code 6.g – 

Triennial Reviews: General Comments. 

With regard to the comments suggesting the CWA provides EPA authority to require states and 

authorized tribes to submit the entirety of its triennial review process (e.g., public comments submitted 

to the state or authorized tribe during triennial review and their response), see EPA’s response in code 

6.f – Triennial Reviews: Proposed Revision. 

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