CHAPTER 3 

Issue Category: Other Changes 

Pages 3-428 – 3-432

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 10.a – Other Changes 

Essay 10.a – Other Changes to the Rule

The U.S. Environmental Protection Agency (EPA) acknowledges the commenters that expressed general 

support for EPA’s proposed changes.

A. Revision to Title 40 of the Code of Federal Regulations Section 131.2 

Some commenters suggested that EPA’s proposed removal of the word “necessary” from section 131.2 

could lead to states and tribes being required or encouraged to adopt overly stringent or unnecessary 

criteria. With regard to these commenters, EPA disagrees. EPA finalized the revisions to section 131.2 as 

proposed. This revision is important to make the language in section 131.2 and section 131.11 

consistent and to alleviate any inconsistent interpretations between these two sections (e.g., that 

section 131.2 requires adoption of criteria sufficiently stringent to protect the designated use but no 

more stringent than that, while section 131.11 does not require such precision but rather requires 

criteria that are protective of the designated use, whether just barely protective or “overly” protective 

(e.g., with a larger margin of error or similar). Section 131.11(a) already includes that states and 

authorized tribes “must adopt those water quality criteria that protect the designated use.” It is not 

EPA’s intent to use this revision to section 131.2 to require or encourage states and authorized tribes to 

adopt criteria that are not necessary to protect their designated uses or to force or encourage states or 

authorized tribes to adopt overly stringent criteria. As required by section 131.11(a), states and 

authorized tribes continue to be required to adopt criteria that are based on sound scientific rationale 

for sufficient parameters or constituents to protect the designated use. EPA notes that, consistent with

Clean Water Act (CWA) section 510, and/or pursuant to their own inherent authority in the case of 

authorized tribes, states and authorized tribes may adopt standards that are more stringent than

minimally required by the CWA, but that is not a result of removing “necessary” from section 131.2. See 

City of Albuquerque v. Browner, 97 F.3d 415, 421-23 (10th Cir. 1996)(regarding inherent tribal 

sovereignty to adopt water quality standards (WQS) more stringent than minimum CWA requirements). 

See also EPA’s response to code 3.a – EPA’s Legal Authority: General Comments concerning state 

primacy in the WQS program.

One commenter suggested that EPA further revise section 131.2 to use language directly from CWA 

section 303(c)(2)(A), “based upon such uses.” EPA disagrees. Incorporating “based on such uses” into 

section 131.2 could result in ambiguity in the regulation (and how it relates to section 131.11) and could 

fail to recognize the additional context for the meaning of “such uses” provided in the second sentence 

of CWA section 303(c)(2)(A). The second sentence reads: “Such revised or new water quality standard 

shall consist of the designated uses of the navigable waters involved and the water quality criteria for 

such waters based upon such uses.” EPA proposed and is finalizing today a rule that includes the more 

precise language “designated uses” to ensure there is no confusion that it refers to the CWA-effective 

designated uses applicable to the waters at issue and not the complete list of uses in CWA section 

303(c)(2)(A) (although there will very likely be some overlap between those two sets of uses). 

With regard to the commenters requesting clarification on the relationship between existing uses and 

designated uses, see EPA’s response to code 5.d – Designated Uses: Existing Uses.

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Several commenters suggested that EPA further revise section 131.2 to include antidegradation 

requirements. The commenters provided different wording, but all with the same purpose. One 

commenter provided a slightly narrower edit requesting that EPA add reference to protecting and 

maintaining existing instream water uses (e.g., Tier 1 of antidegradation). EPA did not propose or finalize 

a revision to add reference to antidegradation requirements, existing uses or Tier 1 protections, or 

descriptions to further explain the meaning of designated uses, criteria, and antidegradation

requirements in section 131.2. EPA did not make such revisions to section 131.2 because the previously 

existing regulations at section 131.6(d) include an antidegradation policy as a minimum requirement for

WQS submissions and Subpart B of Title 40 of the Code of Federal Regulations (CFR) Part 131 

(Establishment of Water Quality Standards) explicitly includes antidegradation policies. In addition, EPA 

concluded it was not necessary to revise section 131.2 because of the revisions to section 131.5(a)(3), 

which clarify EPA’s authority to review and approve or disapprove whether a state (or authorized tribe) 

has adopted an antidegradation policy consistent with section 131.12 and whether any adopted 

antidegradation implementation methods are consistent with section 131.12.

See also EPA’s response to similar suggestion for section 131.3(i) below, under, subheading E -Other. See 

also EPA’s response to code 7.m – Antidegradation: EPA’s Legal Authority for additional discussion on 

EPA’s position that antidegradation requirements are WQS

B. Revision to Title 40 of the Code of Federal Regulations Section 131.5(a)(2) 

EPA agrees with commenters who suggested adding a citation for section 131.11 into section 131.5(a)(2) 

in addition to the proposed edit to add “sound scientific rationale” to make sure there is consistency 

between these provisions. EPA added the citation in the final rule. Another commenter suggested 

replacing “sound scientific rationale” with “consistent with § 131.11.” EPA agrees in part. The final rule 

adds additional language and makes clear that “sound scientific rationale” is linked to the requirements 

of section 131.11. By linking the two regulatory sections, the final rule is clear that this provision does 

not contradict the requirements and flexibilities provided in section 131.11.

Some commenters suggested that EPA is seeking to expand its authority to review criteria by adding 

“sound scientific rationale.” Other commenters expressed concern with the proposed change to section

131.5(a)(2) because “sound scientific rationale” is an ambiguous and subjective point of reference, and 

some commenters suggested replacing “sound scientific rationale” with “best available technology”

(BAT) or “best available science.” EPA disagrees with each of the aforementioned suggestions. The term 

in question, “sound scientific rationale,” is currently used and understood in the criteria section of the 

WQS regulation at section 131.11 (and has been since it was promulgated in 1983), thus EPA sees no 

need to change it to “best available science.” The term “best available technology economically 

achievable” is a legal term of art that has specific meaning related to the technology-based 

requirements under CWA section 304(b) and implementing regulations and is not appropriate in the 

WQS context. By adding a direct citation to section 131.11 in section 131.5(a)(2), the final rule makes it 

clear that EPA is not increasing or decreasing the burden of proof for states and authorized tribes, but is 

rather pointing to the very same analysis that currently exists in the relevant criteria section. For the 

same reasons, EPA also disagrees that inclusion of “sound scientific rationale” is an expansion of its 

review authority as referenced in section 131.5(a)(4), section 131.6(b) or section 131.6(f).

One commenter suggested that the proposed change to section 131.5(a)(2) may interfere with the 

ability of states and authorized tribes to use narrative criteria. EPA disagrees. As stated above, this 

revision does not create a new or different level of required protection or change the stringency of 

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requirements for states and authorized tribes with respect to criteria. States and authorized tribes 

continue to have the discretion to establish narrative criteria as described in section 131.11(b)(2), as 

long as such criteria are protective of applicable designated uses and based on sound scientific rationale. 

EPA disagrees with a commenter that questioned whether there is sufficient consistency between 

section 131.5 and section 131.6. EPA disagrees that the minor wording differences (e.g., “use 

designations” vs. “designated water uses”) cause confusion. EPA has not encountered confusion from 

states and authorized tribes over this point in the past and did not receive many comments on it. EPA 

agrees with the commenter that it is important that the final changes to the section 131.5 be consistent 

with section 131.6 and with the other parts of section 131. The final rule requirements section 131.5 are 

consistent with section 131.6 and with the other parts of the rule. EPA notes that section 131.5 and 

section 131.6 are different and distinct sections, which is why although they are consistent, they are not 

identical. In section 131.6, the regulation outlines the minimum elements that are required to be 

included in a state or authorized tribal WQS submission. In section 131.5, the regulation outlines EPA’s 

authority to review and to approve or disapprove WQS. The sections are necessarily different because of 

their different functions. For example, section 131.6 requires that states and authorized tribes submit 

methods and analyses as supporting documentation along with their WQS submission. This is required 

so that EPA will be able to evaluate the basis for the new or revised WQS. However, section 131.5 does 

not discuss supporting documentation, because EPA does not have authority to act on it under CWA 

303(c). Because each of these sections serves a different purpose, it is important that each is 

independently clear. This is also the reason that EPA disagrees with the commenter that the two 

sections should be combined.

One commenter suggested that EPA revise section 131.5(a)(2) (which describes what EPA’s review 

involves a determination of) to refer to whether a State has adopted criteria that protect the designated 

uses “that are supported by a” sound scientific rationale, rather than “based on” a sound scientific 

rationale. EPA disagrees with the commenter’s suggestion and did not make this change in the final rule. 

The regulation at section 131.6(b) requires that states and tribes must submit methods and analyses, 

which would include their sound scientific rationales, to support their WQS revisions. EPA does not view 

the term “supported by a sound scientific rationale” as providing EPA a different basis for approval than 

the phrase “based on a sound scientific rationale.” Therefore, EPA views the commenter’s suggested 

change as unnecessary.

C. Revision to Title 40 of the Code of Federal Regulations Section 131.5(a)(3) 

With regard to the commenter suggesting that section 131.5(a)(3) is too vague and questioning what 

elements a State’s antidegradation policy must include to be consistent with section 131.12(a), see 

EPA’s response to 7.f.i – Antidegradation Implementation Methods: Transparency and Adoption.

D. Revision to Title 40 of the Code of Federal Regulations Section 131.12(a)(2) 

Some commenters suggested that “assure” and “ensure” are synonyms and requested EPA not finalize 

the proposed change to section 131.12(a)(2). Other commenters suggested that the term “ensure” 

would impose a higher burden of proof on states and authorized tribes as they would need to guarantee 

an outcome of water quality. One commenter suggested replacement of “ensure” with “specify” to 

address similar concerns. EPA further explored the meaning of both words, and today’s final rule retains 

the existing regulation’s language using “assure” in section 131.12(a)(2). While EPA found that both 

“assure” and “ensure” mean “to make sure” and in some cases may be used interchangeably, EPA also 

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recognizes that context surrounding the word is important. While “ensure” is used in another section of 

the WQS regulation (see section 131.10(b)), that section is related to ensuring state or authorized tribal 

WQS set standards to address a specific issue (i.e., downstream protection). In this context, the states 

and authorized tribes have control of setting their standards and can “make sure” those WQS meet the 

regulatory requirements. In the case of section 131.12(a)(2), the section is addressing water quality, not 

WQS. While states and authorized tribes have control over setting their WQS, they do not have the 

same control over the resulting water quality, so “ensure” would not be appropriate in the section

131.12(a) context. Thus, EPA found that it is appropriate to use “assure” in section 131.12(a)(2).

Some commenters suggested that EPA’s use of the term “ensure” would lead to litigation related to 

states’ and authorized tribes’ analysis of alternatives. Today’ final rule does not finalize use of the term 

“ensure” and retains the use of “assure.” In response to comments related to a state’s discretion 

regarding the analysis of alternatives, see EPA’s response to code 3.a – EPA’s Legal Authority: General 

Comments. See also EPA’s response to codes 7.e.ii – Antidegradation Alternatives Analysis: General 

Opposition for Proposed Revision, 7.e.iii – Antidegradation Alternatives Analysis: Suggested Alternatives 

That Should/Shouldn’t Be Considered, and 7.e.iv – Antidegradation Alternatives Analysis: Selecting an 

Alternative.

With regard to inserting “the protection and” before the phrase “propagation of fish, shellfish and 

wildlife” in section 131.12(a)(2), one commenter suggested this insertion was unnecessary because if a 

species is propagating, then it is inherently being protected at a sustainable level. The commenter also 

expressed concern that this change adds a new level of protection than expected previously. EPA 

disagrees that inserting “the protection and” is unnecessary and adds a new level of protection. The 

entire phrase “the protection and propagation of fish, shellfish, and wildlife and provides for the 

recreation. . .” comes directly from section 101(a)(2) of the CWA and EPA finalized the proposed change 

to make section 131.12(a)(2) consistent with CWA section 101(a)(2) and the rest of the WQS regulation, 

as well as the CWA. In other words, this has been a requirement of the CWA since at least 1983, and 

arguably 1972, and EPA is only making this change to make the various provisions consistent with each 

other re this language. 

See also EPA’s response to code 12.c – Economics: EPA’s Burden and Costs in response to comments on 

the “unacceptable burden” imposed by the proposed edits.

E. Other

With regard to the commenter suggesting language related to section 131.3(m), see EPA’s response to 

codes 5.e – Designated Uses: Definitions/Terms, 8.g.ii – Variance Submission Requirements: Numeric 

Interim Requirements, and 8.c – Variances: Proposed Definition regarding the definition of highest 

attainable use (HAU) and the meaning of highest attainable condition (HAC) and protection of existing 

uses. 

One commenter suggested that EPA add reference to States’ antidegradation policy in section 131.3(i), 

the definition of WQS and references section 130.7(b). EPA did not propose or finalize a revision in 

section 131.3(i) because EPA concluded it was not necessary considering the revisions to section

131.5(a)(3) and the existence of provisions that are already explicit to antidegradation in section 131.6 

and section 131.12.

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See also EPA’s response to code 7.g.iii – Antidegradation: Suggested Changes/Revisions to Minimum 

Elements for a discussion regarding antidegradation and CWA section 303(d) and EPA’s response to 

code 7.m – Antidegradation: EPA’s Legal Authority for discussion on EPA’s position that antidegradation 

requirements are WQS. 

One commenter suggested that EPA remove the sentence referring to states’ continuing planning 

process (CPP) from section 131.20(a). EPA disagrees. EPA did not propose or finalize removal of this 

sentence in section 131.20(a) because CPPs can be a valuable WQS planning tool and where the state’s 

CPP is binding and the requirements are WQS, EPA has the duty and authority to act on them under 

CWA section 303(c).1

 

1 http://water.epa.gov/scitech/swguidance/standards/cwa303faq.cfm

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