UNITED STATES ENVIRONMENTAL PROTECTION 

AGENCY 

REGION I 

5 POST OFFICE SQUARE SUITE 100 

BOSTON, MASSACHUSETTS 02109-3912 

June 5, 2015

Patricia W. Aho, Commissioner

Maine Department of Environmental Protection

17 State House Station

Augusta, ME 04333-0017

Re: Review of and Decisions on Maine Water Quality Standards 

Dear Commissioner Aho:

On February 2 and March 16, 2015, EPA issued decisions approving or disapproving Maine’s 

new and revised water quality standards (“WQS”) adopted between 2003 and 2014 (as well as 

certain WQS that were adopted prior to 2003) as they relate to waters in Indian lands in Maine. 

In the February 2 decision, EPA explained that EPA had never approved (or disapproved) any 

WQS for waters in Indian lands in Maine until that date, and stated its intent to review and 

approve or disapprove all remaining Maine WQS that could apply to waters in Indian lands as 

soon as possible. This letter contains EPA’s decisions on those remaining WQS that EPA has 

not yet acted on as applied to waters in Indian lands.1 In addition, as explained below, this 

letter includes some decisions regarding new or revised WQS provisions that EPA had never 

before approved or disapproved for any waters in Maine, and these decisions apply to all waters

of the State.

In order to determine what WQS still needed to be reviewed and approved or disapproved for 

waters in Indian lands, EPA reviewed the statutes and rules submitted by Maine Department of 

Environmental Protection (“DEP”) on May 23, 2000 (which updated Maine’s initial submittal 

of June 21, 1999) to EPA’s water quality standards repository for Maine,

2

and also searched its 

files for any WQS submitted between May, 2000 and December, 2003. EPA reviewed all of 

the provisions in those statutes and rules and identified those WQS that EPA had not yet

approved or disapproved in the decisions referenced above.3 EPA’s decisions on these 

remaining WQS are set forth below and discussed in the paragraphs that follow. 

 

1 Because EPA has never acted on pre-2003 WQS for waters in Indian lands, they remain “new or revised” WQS 

as to those waters and thus subject to EPA review and approval or disapproval pursuant to CWA § 303(c).

2 http://water.epa.gov/scitech/swguidance/standards/wqslibrary/me_index.cfm.

3 Of those submissions, the only new or revised WQS that EPA did not review is DEP Rule Chapter 530.5, which 

was repealed in 2005. 
2

EPA learned during review of its historic files that the Agency had never formally approved or 

disapproved some of the State’s new or revised WQS for any waters in Maine (or could find no 

record of ever having done so), most of which Maine submitted before May 30, 2000,4but one 

of which Maine submitted in 2001. For those WQS, EPA’s decisions today apply to waters 

both inside and outside Indian lands, and we have identified such WQS decisions below.

5, 6

EPA today is disapproving on a statewide basis several new or revised WQS that were adopted 

and submitted before May 30, 2000. Pursuant to 40 C.F.R. § 131.21(c), those WQS took 

immediate effect in waters outside Indian lands for Clean Water Act purposes upon submission 

to EPA, and following EPA’s disapproval they will remain in effect in waters outside Indian 

lands until the State promulgates (and EPA approves), or EPA promulgates, replacement WQS. 

Lastly, EPA identified a number of provisions that EPA is not taking action on because we 

have concluded that they are not WQS requiring EPA review and approval; these are identified 

at the end of this letter. 

EPA has attempted to be as thorough as possible, but if we inadvertently overlooked a WQS 

that would apply to waters in Indian lands, we would appreciate DEP’s bringing that to our 

attention as soon as possible so that we can take action on any such WQS. 

Approvals

Pursuant to Section 303(c)(3) of the CWA and 40 C.F.R. part 131, I hereby approve the 

following new and revised water quality standards for all waters throughout Maine, including 

in Indian lands:

 38 M.R.S. § 361-A – Definitions: Discharge, Agricultural activities, Commissioner, 

Board, Department, Pollutant, and Waters of the state;

 38 M.R.S. § 413(11.D) – Antidegradation provision for mercury discharges;

 38 M.R.S. § 414-A(1.A, 1.B, and 1.C) –Tier 1 and 2 antidegradation provisions; and 

§ 414-A(2) – language that authorizes the use of compliance schedules in discharge 

licenses to meet final effluent limitations based on a water quality standard adopted 

after July 1, 1977;

 38 M.R.S. § 464(2-A) – Requirements and limitations for the removal of designated 

uses and creation of subcategories of uses;

 

4 For some new or revised WQS in Maine, it is not clear from EPA’s records whether the State submitted them to 

EPA for review at the time of enactment. However, EPA considers any WQS included as part of Maine’s May 23, 

2000 submission to the WQS repository to have been submitted to EPA before May 30, 2000 for the purposes of 

40 C.F.R. § 131.21(c). 

5

In the event it comes to light that EPA did previously approve any such standards in state waters, then the date of 

that earlier action would be the operative approval date.

6 EPA is not specifically identifying ministerial or nonsubstantive revisions (e.g., changing “department” from 

“commissioner,” or changing “is” from “shall be”) to previously approved WQS but is hereby approving them as 

applicable to all waters.
3

 38 M.R.S. § 464(2-B) – Temporary removal of uses, use attainability analysis, and 

creation of subcategories of uses for combined sewer overflows;

 38 M.R.S. § 464(4.D) – Policy for determining the assimilative capacity of a river or 

stream (second and third sentences);

 38 M.R.S. § 464(4.H) – Habitat and aquatic life criteria for new (post-1992) 

hydropower projects;

 38 M.R.S. § 464(9-A.D and 9-A.E) – Habitat and aquatic life criteria for existing 

hydropower impoundments managed as great ponds;

 38 M.R.S. § 464(10) – Habitat and aquatic life criteria for existing hydropower 

impoundments managed under riverine classifications;

 38 M.R.S. § 465(1.C.(3) and (5)) –Certain exceptions to prohibition on discharges to 

Class AA waters; 

 38 M.R.S. § 465(4.B., the last two sentences) – Direction to adopt rules for 

identification of fish spawning areas; and 

 38 M.R.S. § 465-B(1.C.(3) and (4)) –Certain exceptions to prohibition on discharges to 

Class SA waters.

Pursuant to Section 303(c)(3) of the CWA and 40 C.F.R. part 131, I hereby approve the 

following new and revised water quality standards for specific waters outside of waters in 

Indian lands:

 38 M.R.S. § 464(9-A.A) – Habitat and aquatic life criteria for existing hydropower 

impoundment above the Ripogenus dam; and

 38 M.R.S. § 464(11) – Habitat and aquatic life criteria for four river segments 

downstream of existing hydropower impoundments.

Pursuant to Section 303(c)(3) of the CWA and 40 C.F.R. part 131, I hereby approve the 

following new and revised water quality standards for all waters in Indian lands:

 38 M.R.S. § 361-A – Definitions: Fresh surface waters and Estuarine and marine 

waters;

 38 M.R.S. § 414-C(3) – Instream color pollution standard;
4

 38 M.R.S. § 420(2) and (2.A-G)7– Introductory paragraph of section 2, which 

addresses the definition of “toxic substance” and how toxic substances are to be 

addressed in WQS; the requirement in 2.A to regulate toxic substances at the levels 

recommended by EPA, pursuant to CWA Chapter 304(a), and the exception to that 

requirement for naturally occurring toxic substances but only as it pertains to aquatic 

life criteria8; and the provisions in 2.B through 2.G, related to responsibility and 

authority for the adoption of statewide and site specific criteria for toxic substances in 

regulation;

 38 M.R.S. § 464(1) – Language that identifies the findings, objectives and purpose of 

Maine’s WQS;

 38 M.R.S. § 464(2) – Procedures for reclassification;

 38 M.R.S. § 464(4.A(3)) – Language providing Tier 1 protection, but not including the 

exceptions at 4.A(3)(a) and (b), which EPA disapproved in its February 2, 2015 

decision; § 464(4.A(4)) – narrative criteria related to color, taste, and other properties; 

and § 464(4.A(5)) – pH criterion for estuarine and marine waters9;

 38 M.R.S. § 464(4.B) – Narrative criteria for settled and floating substances;

 38 M.R.S. § 464(4.C)) – Natural conditions clause as it applies to aquatic life criteria10;

 38 M.R.S. § 464(4.D) – Policy for determining the assimilative capacity of a river or 

stream (first sentence);

 38 M.R.S. § 464(4.E) – Waters in excavations for wastewater treatment purposes;

 38 M.R.S. § 464(4.F.(1) – (5)) – Antidegradation policy;

 38 M.R.S. § 465(1.B) – Narrative criteria for aquatic life and dissolved oxygen in Class 

AA waters;

 38 M.R.S. § 465(1.C.(2) and (4)) – Prohibition, and certain exceptions to prohibition on 

discharges to Class AA waters;

 38 M.R.S. § 465(2.B) – Narrative criteria for aquatic life in Class A waters;

 38 M.R.S. § 465(2.C, first paragraph) – General requirements on discharges to Class A 

waters;

 

7 We note that 38 M.R.S. § 420(2.H) is obsolete and therefore not before EPA for action.

8 EPA is disapproving the exception in 38 MRS §420(2.A) for naturally occurring toxic substances as it applies to 

human health criteria. See below.

9 EPA is disapproving the pH criterion for freshwaters in 38 M.R.S. § 464(4.A(5)). See below.

10 EPA is disapproving the natural conditions clause in 38 M.R.S. § 464(4.C)) as it applies to human health 

criteria. See below.
5

 38 M.R.S. § 465(3.B) – Numeric criteria for dissolved oxygen in Class B waters;

 38 M.R.S. § 465(3.C) – Narrative criteria for aquatic life in Class B waters;

 38 M.R.S. § 465(4.C) – Narrative criteria for aquatic life in Class C waters;

 38 M.R.S. § 465-A(1.B) – Narrative eutrophication criteria in Class GPA waters;

 38 M.R.S. § 465-B(1.B) – Narrative criteria for estuarine and marine life and dissolved 

oxygen in Class SA waters;

 38 M.R.S. § 465-B(1.C.(2)) – Prohibition, and certain exception to prohibition on 

discharges to Class SA waters;

 38 M.R.S. § 465-B(2.B) – Numeric dissolved oxygen criteria and bacteria criteria for 

the protection of shellfishing in Class SB waters;

 38 M.R.S. § 465-B(2.C, first sentence) – Narrative criteria for estuarine and marine life 

in Class SB waters;

 38 M.R.S. § 465-B(3.B) – Numeric dissolved oxygen criteria and bacteria criteria for 

the protection of shellfishing in Class SC waters;

 38 M.R.S. § 465-B(3.C) – Narrative criteria for estuarine and marine life in Class SC 

waters; 

 38 M.R.S. § 466 – Definitions: Aquatic life, As naturally occurs, Color pollution unit,

Combined sewer overflow, Community function, Community structure, Direct 

discharge, Estuarine and marine life, Indigenous, Invasive species, Natural, Resident 

biological community, Unimpaired, Use attainability analysis, and Without detrimental 

changes in the resident biological community;

 38 M.R.S. § 636(8) – Certification and reclassification provisions related to proposed 

hydropower impoundments;

 DEP Rule Chapter 581 – Regulations relating to water quality evaluations including: 

hydrologic conditions for computing assimilative capacity in rivers and streams and in 

great ponds; minimum flows on regulated streams; zone of passage; and great ponds 

trophic state;

 DEP Rule Chapter 582(1) – Freshwater temperature criteria11; and

 DEP Rule Chapter 585– Identification of fish spawning areas and designation of 

salmonid spawning areas.

 

11 EPA is disapproving the tidal temperature criteria in DEP Rule Chapter 582(2). See below.
6

Disapprovals

Pursuant to Section 303(c)(3) of the CWA and 40 C.F.R. part 131, I hereby disapprove the 

following new and revised water quality standards for all waters throughout Maine, including 

in Indian lands:

 38 M.R.S. § 363-D – Waiver or modification of protection and improvement laws;

 38 M.R.S. § 465(2.B) – Numeric criteria for dissolved oxygen in Class A waters; and

 38 M.R.S. § 465(1.C.(1)) and § 465-B(1.C.(1)) – Exceptions to prohibitions on 

discharges to Class AA waters and Class SA waters, respectively.

Pursuant to Section 303(c)(3) of the CWA and 40 C.F.R. part 131, I hereby disapprove the 

following new and revised water quality standards for all waters in Indian lands:

 38 M.R.S. §420(2.A) – Exception for naturally occurring toxic substances from the 

requirement to regulate toxic substances at the levels recommended by EPA, as it 

applies to human health criteria;

 38 M.R.S. § 451 – Mixing zone policy;

 38 M.R.S. § 464(4.A.(5)) – pH criterion for freshwaters;

 38 M.R.S. § 464(4.C)) – Natural conditions clause, as it applies to human health 

criteria;

 38 M.R.S. § 465(1.B), § 465(2.B) and § 465-B(1.B) – Narrative criteria for bacteria in 

Class AA, A, and SA waters, respectively; and

 DEP Rule Chapter 582(5) – Tidal temperature criteria.

Supporting Discussion of Approvals

Findings, Objectives and Purpose [38 M.R.S. §464(1)]

EPA is approving the findings, objectives and purpose expressed in 38 M.R.S. §464(1) because 

they are consistent with the goals expressed in Section 101(a) of the CWA.

Definitions [38 M.R.S. § 361-A and 38 M.R.S. § 466]

EPA is approving the definitions in 38 M.R.S. §§ 361-A and 466 specified above because they 

are integral to the WQS program and, in the case of definitions of terms that are also contained 

in the CWA and the federal WQS, they are generally as broad and protective as the federal 
7

terms.12 We note that § 361-A refers to the Code of Federal Regulations and the Federal Water 

Pollution Control Act, both as amended through July 1, 2009. We encourage Maine to update 

these references when it makes other revisions to its WQS.

Procedures for Reclassifications, Removals of Designated Uses, and Creation of 

Subcategories of Uses [38 M.R.S. § 464(2), (2-A), and (2-B)]

EPA approves the provisions of 38 M.R.S. § 464(2), (2-A), and (2-B) because they are 

consistent with the requirements of section 303 of the CWA and with provisions regarding 

designated uses, removals of uses and creations of subcategories of uses in 40 C.F.R. §131.10.

Natural Conditions Clauses as They Apply to Aquatic Life Criteria [38 M.R.S § 464(4.C) 

and 38 M.R.S § 420(2.A)]

EPA’s review of Maine’s natural conditions clauses at 38 M.R.S § 464(4.C) and § 420(2.A) as 

they apply to aquatic life criteria is based on whether the clauses protect designated aquatic life 

uses. The clause in 38 M.R.S § 464(4.C) says that, “Where natural conditions, including but 

not limited to, marshes bogs and abnormal concentrations of wildlife cause the dissolved 

oxygen criteria or other water quality criteria to fall below the minimum standards...those 

waters shall not be considered to be failing to attain their classification because of those natural 

conditions.” The clause in 38 M.R.S. § 420(2.A) says, “Except as naturally occurs or as 

provided in paragraphs B and C, the board shall regulate toxic substances in the surface waters 

of the State at the levels set forth in federal water quality criteria as established by the United 

States Environmental Protection Agency pursuant to the Federal Water Pollution Control 

Act....” 

These provisions are consistent with EPA’s interpretation of the relationship between natural 

conditions and the protection of designated aquatic uses, which is articulated in EPA's 

November 1997 guidance entitled Establishing Site Specific Aquatic Life Criteria Equal to 

Natural Background.

13 EPA recognizes that there may be naturally occurring concentrations of 

pollutants which exceed the national criteria published under section 304(a) of the CWA. The 

policy states that "For aquatic life uses, where the natural background concentration for a 

specific parameter is documented, by definition that concentration is sufficient to support the 

level of aquatic life expected to occur naturally at the site absent any interference by humans."

EPA approves the natural conditions clauses at 38 M.R.S §464(4.C) and § 420(2.A) as they 

apply to criteria that protect aquatic life because the application of this provision protects 

designated aquatic life uses as required by the CWA and federal water quality standards 

regulations at 40 C.F.R. § 131.11(a). 

 

12 In any case, for Clean Water Act purposes, federal definitions would apply in the event they are broader than 

state definitions. 

13 Davies, Tudor, EPA. Establishing Site Specific Aquatic Life Criteria Equal to Natural Background, November 

5, 1997. 
8

Hydrologic Conditions for Computing Assimilative Capacity [38 M.R.S. § 464(4.D) and 

DEP Rule Chapter 581(1) - (3)]

Title 38 M.R.S. § 464(4.D) requires that the minimum 7-day low flow which can be expected 

to occur with a frequency of one in ten years (7Q10 low flow) be used for the purpose of 

computing whether a discharge will violate the classification of any river or stream, unless 

otherwise provided for toxic substances and consistent with the risk being addressed. This 

provision is supplemented by DEP Rule Chapter 530(4.B), which provides greater specificity 

for flows to be used with acute aquatic life criteria (1/4 of 1Q10) and with human health criteria 

(harmonic mean flow). EPA approved DEP Rule Chapter 530(4.B) for waters in Indian lands 

in our February 2, 2015 decision.

Sections 1, 2, and 3 of DEP Rule Chapter 581 also address the hydrologic assumptions to be 

used when calculating whether a discharge will violate the classification of rivers, streams and 

great ponds. Section 1 repeats the requirements in at 38 M.R.S. § 464(4.D) by requiring that 

the 7Q10 low flow be used for the purpose of computing assimilative capacity in rivers and 

streams. Section 2 authorizes DEP to establish minimum flow requirements in regulated rivers 

and streams where necessary to maintain WQS. Finally, section 3 requires that hydraulic 

residence time be used in great ponds for the purpose of computing assimilative capacity and 

provides a formula for calculating the hydraulic residence time. 

As explained in Section 5.2 of EPA’s Water Quality Standards Handbook, critical low flow 

values are important for criteria implementation, to help ensure that criteria are protective of 

uses.14 In the Technical Support Document for Water Quality-based Toxics Control,

15 EPA 

also explained that critical flows are necessary to provide a dimension of frequency and 

duration of pollutant exposure for the evaluation of “reasonable potential”16 and the derivation 

of permit effluent limits. EPA approves the provisions related to hydrologic assumptions for 

critical flow, maintenance of critical flow, and hydraulic residence time in 38 M.R.S. § 

464(4.D) and DEP Rule Chapter 581(1), (2), and (3) because they are consistent with EPA’s 

recommendation that states provide critical low flow values in their WQS, and the values 

themselves are protective of designated uses.

Antidegradation Policy and Related Provisions [38 M.R.S. § 464(4.F.(1)-(5)); 38 M.R.S. § 

414-A(1.A, 1.B, and 1.C); 38 M.R.S § 413(11.D); and 38 M.R.S. § 465(2.C, first 

paragraph)]

1. 38 M.R.S. § 464(4.F.(1)-(5)) – Maine’s antidegradation policy is set forth in 38 M.R.S. § 

464(4.F.(1)-(5)). As described below, EPA approves 38 M.R.S. § 464(4.F.(1)-(5)) because it is 

consistent with the federal antidegradation policy at 40 C.F.R. § 131.12. 

Subsection 1 requires existing instream water uses and the water quality necessary to protect 

the existing uses to be maintained and protected, and it identifies various factors DEP must 

 

14 EPA, Water Quality Standards Handbook - Chapter 5: General Policies, Section 5.2, 2015 online version.

15 EPA, Technical Support Document for Water Quality-based Toxics Control, EPA/505/2-90-001, March 1991, 

Appendix D, page D-6.

16 “Reasonable potential” refers to the requirement in 40 C.F.R. § 122.44(d) that limitations control all pollutants 

that that may be discharged at a level which will have the reasonable potential to cause an excursion above any 

state water quality standard.
9

consider in determining the existing uses of a water body. Often referred to as “Tier 1” 

protection, this provision is consistent with 40 C.F.R. § 131.12(a)(1). Subsection 1-A further 

provides that any proposed activity will not have a significant impact on or cause significant 

degradation of existing uses.

Subsection 2 provides that where high quality waters constitute an outstanding national 

resource, that water quality must be protected and maintained. It also identifies the waters that 

are considered to be outstanding national resource waters (“ONRWs”), including all Class AA 

and SA waters, and waters in national and state parks, wildlife refuges, and public reserved 

lands. Often referred to as “Tier 3” protection, the ONRW provision affords the highest level 

of protection for waters, and it is consistent with 40 C.F.R. § 131.12(a)(3). 

Subsection 3 provides protection for both existing and designated uses by allowing discharge 

licenses to be issued only if the receiving waterbody is meeting applicable WQS and 

antidegradation requirements; or, where the water body is not meeting applicable WQS, only if 

the discharge will not cause or contribute to the failure to meet WQS. 

Subsection 4 adds further protection of uses by requiring that if the quality of water in a 

waterbody exceeds the minimum standards of the next highest classification, the Board of 

Environmental Protection must recommend to the Legislature that the waterbody be 

reclassified to that next highest classification.

Subsection 5 protects against the lowering of existing water quality in any water body unless 

DEP finds, after an opportunity for public participation, that the action is necessary to achieve 

important economic or social benefits to the State and that the action is in compliance with 

subsection 3 (described above). The protection of high quality waters in subsection 5, often 

referred to as “Tier 2” protection, ensures that water quality that is better than the minimum 

needed to attain WQS will be maintained unless the lowering of water quality satisfies specific 

requirements. EPA interprets the finding required in subsection 5, that “the action [i.e., the 

lowering of water quality] is necessary to achieve important economic or social benefits to the 

State,” to include a required finding that such lowering is necessary to achieve such benefits “in 

the areas in which the waters are located,” as required in 40 C.F.R. § 131.12(a)(2), and 

therefore concludes that it is consistent with the federal regulation. 

In addition to the statutory Tier 2 provisions, EPA considered DEP’s waste discharge license 

guidance and regulations to determine how Maine interprets those provisions when 

implementing Tier 2 of its antidegradation policy. DEP’s waste discharge program guidance 

for implementing antidegradation (2001) provides that, in allowing the lowering of water 

quality, “there shall be achieved the highest statutory and regulatory requirements for all new 

and existing point sources and all cost-effective and reasonable best management practices for 

nonpoint sources,” as required by 40 C.F.R. § 131.12(a)(2). Further, although 38 M.R.S. § 366, 

which DEP previously relied on to satisfy the intergovernmental coordination requirement of § 

131.12(a)(2), has been repealed, DEP Rule Chapter 522, which governs waste discharge license 

issuance procedures, provides for intergovernmental coordination in § 8.c, by requiring notice 

of permit applications and public hearings to be provided to multiple state agencies, ensuring 

that such agencies would have the opportunity to comment on any wastewater discharge project 

that proposes a lowering of water quality. Therefore, EPA has determined that 38 M.R.S. § 

464(4.F(5)) meets the requirements of EPA’s regulations at 131.12(a)(2).
10

EPA approved some sections of 38 M.R.S. § 464(4.F) in 1986 and did not act on others; 

disapproved a section in 1987; and then approved the remainder of § 464(4.F), including 

revisions that satisfactorily addressed the disapproval, in 1990. EPA is today approving 38 

M.R.S. § 464(4.F(1)-(5)) in its entirety for tribal waters because it is consistent with 40 C.F.R. 

§ 131.12. At the same time, EPA recommends that Maine clarify and strengthen certain 

aspects of its Tier 2 protection for all waters. The upcoming triennial review would be a good 

opportunity for Maine to revise § 464(4.F.(5)) to explicitly provide for intergovernmental 

coordination, and to require the assurance related to point and nonpoint sources quoted above. 

Such revisions would clarify and ensure that these requirements will apply to projects that are 

the subject of CWA section 401 certifications from Maine, as well as to waste discharge 

licensees.

2. 38 M.R.S. § 414-A(1.A, 1.B, and 1.C) – EPA approves the antidegradation provisions in 38 

M.R.S. § 414-A(1.A, 1.B, and 1.C). Section 414-A(1.A and 1.B) provide Tier 1 

antidegradation protection by ensuring that discharges, either alone or in combination with 

others, will not lower the water quality of a water body below its classification (subsection 1.A) 

or below the classification which the board expects to adopt for such water body (subsection 

1.B). Section 414-A(1.C) provides Tier 2 antidegradation protection by prohibiting discharges 

from lowering existing water quality unless 38 M.R.S. § 464(4.F), and certain specified 

elements of Tier 2 of the antidegradation policy, are satisfied. All of these provisions 

supplement and are consistent with 38 M.R.S. § 464(4.F), and they are consistent with 40 

C.F.R. § 131.12(a)(1) and (2). 

3. 38 M.R.S. § 413(11.D) – EPA approves the antidegradation provision in 38 M.R.S. § 

413(11.D) related to mercury discharges. The end of the first paragraph in 38 M.R.S. § 

413(11) requires facilities that discharge mercury to meet interim limits established under 

paragraph 11, “notwithstanding” 38 M.R.S. § 464(4.F)) (Maine’s antidegradation policy). 

Among such interim limits are those that may be established under § 413(11.D) for a new or 

expanded discharge of mercury provided that specified requirements, which are essentially a 

restatement of Tier 2 antidegradation provisions, are satisfied. EPA’s approval of § 413(11.D) 

is based on the understanding that it is merely a confirmation that a new or expanded discharge

of mercury must satisfy Tier 2 antidegradation requirements, and that the introductory 

“notwithstanding” language does not mean that the full scope of the antidegradation policy at § 

464(4.F), including Tier 1 and Tier 3 protection, is inapplicable to such discharges. Because of 

the ambiguity created by the introductory “notwithstanding” clause, however, EPA requests 

confirmation from Maine’s Attorney General that EPA’s interpretation upon which it bases this 

approval is correct.

4. 38 M.R.S. § 465(2.C) – The first paragraph of 38 M.R.S. § 465(2.C) requires discharges to 

Class A waters licensed after January 1, 1986 to meet an effluent quality equal to or better than 

the receiving water, and to demonstrate that the discharge is necessary and there are no 

reasonable alternatives available; and it allows discharges licensed before that date to continue 

only until practical alternatives exist. EPA approves these provisions because they supplement 

the antidegradation provisions of § 464(4.F) and strengthen the protection of the designated 

uses of Class A waters.
11

Class GPA Trophic State Criteria [38 M.R.S § 465-A(1.B) and DEP Rule Chapter 581(6)]

EPA’s review of the narrative criteria, in 38 M.R.S § 465-A(1.B), for the trophic state of Class 

GPA waters and the numeric criteria for the trophic state of great ponds and lakes, in DEP Rule 

Chapter 581(6), is based on whether the criteria support designated uses for those waters. 

The narrative criteria in 38 M.R.S § 465-A(1.B) state that Class GPA waters must have a stable 

or decreasing trophic state (as measured by chlorophyll “a” content, Secchi disk transparency, 

total phosphorus content and other appropriate criteria), subject only to natural fluctuations, and 

must be free of culturally induced algal blooms that impair their use and enjoyment. The 

narrative criteria are explicitly protective of uses and are based, at least in part, on a causal 

measure (phosphorus) and response indicators (chlorophyll “a” and Secchi disk transparency) 

that EPA agrees are good indicators of eutrophication.17

DEP Rule Chapter 581(6) is entitled “Great Ponds Trophic State,” but includes references to 

“all lakes” and GPA waters. Therefore, EPA understands that DEP Rule Chapter 581(6) 

applies to all Class GPA waters as defined in 38 M.R.S § 465-A(1) to be “great ponds and 

natural ponds and lakes less than 10 acres in size” and that it is intended to provide a numeric 

interpretation of the “stable or decreasing trophic state” part of the narrative criteria in 38 

M.R.S § 465-A(1.B). Chapter 581(6) provides that a GPA water cannot be considered to have 

a stable or declining trophic state if values of the Maine Trophic State Index (TSI) are 

increasing or there is an onset of algal blooms. The TSI is calculated using chlorophyll “a” 

unless the lake is colored (less than 30 standard platinum units), in which case the basis for the 

calculation is total phosphorus concentration or mean Secchi disk transparency. Algal blooms 

are defined as planktonic growth of algae which causes Secchi disk transparency to be less than 

2.0 meters. EPA finds that these are reasonable measures for identifying whether the trophic 

state of a lake is increasing, which can be an early warning sign that cultural eutrophication is 

occurring. 

EPA approves both the narrative criteria in 38 M.R.S. § 465-A(1.B), because they explicitly 

protect designated uses, and the provisions of DEP Rule Chapter 581(6), because they provide 

a scientifically sound numeric interpretation of a part of the narrative criteria, which enhances 

the protection of uses.

Zone of Passage [DEP Rule Chapter 581(5)]

EPA’s review of the provision in DEP Rule Chapter 581(5) is based on whether the provision is 

protective of designated uses. The provision requires that all discharges shall provide for a

zone of passage for free-swimming and drifting organisms that is at least three quarters of the 

cross-sectional area at any point in the receiving water. The zone of passage can be smaller if

the discharger can demonstrate that because of physical phenomena in the receiving water 

body, such a minimum zone cannot be maintained and the minimum zone is not necessary to 

protect organisms in the receiving water from substantial adverse effect. 

 

17

 EPA, Nutrient Criteria, Technical Guidance Manual, Lakes and Reservoirs, First Edition, EPA-822-B00-001, 

April 2000, pages 1-12 to 1-13.
12

EPA guidance provided in the Water Quality Standards Handbook18 recommends that where 

there is incomplete mixing in a receiving water, pollutant loading be limited so that mixing 

zones are small enough to allow a zone of passage for free swimming and drifting organisms 

without significant adverse effects on their populations, including migration for anadromous 

and catadromous species. EPA approves Maine’s provision because it ensures that there will be 

ample passage for free-swimming and drifting organisms outside the mixing zone, and where 

the zone of passage needs to be smaller, the provision guards against substantial adverse effects

to such organisms. Therefore the provision is consistent with EPA’s guidance and protective of 

the aquatic life designated use. 

Waters Contained in Excavations Approved for Wastewater Treatment Purposes [38 

M.R.S. § 464(4.E)]

The provision in 38 M.R.S. § 464(4.E) identifies as unclassified (and thus without designated 

uses) those waters contained in excavations approved for wastewater treatment purposes. EPA 

approves this provision with the understanding that it is limited to waters that are “waste 

treatment systems” that do not fall within Clean Water Act jurisdiction as “waters of the United 

States,” as provided at 40 C.F.R. § 122.2. 

WQS Related to Hydropower Projects [38 M.R.S. § 464(4.H), (9-A.A), (9-A.D), (9-A.E), 

(10), and (11); and 38 M.R.S. § 636(8)]

1. 38 M.R.S. § 464(4.H), (9-A.D), (9-A.E), (10), and (11) – EPA has reviewed the revised 

WQS related to hydropower projects in 38 M.R.S. § 464(4.H), (9-A.D), (9-A.E), (10), and (11), 

all of which were initially enacted in essentially the same form in 1992 (P.L. 1992, c. 813), and 

which clarify water quality classifications and criteria applicable to hydropower impoundments 

and water segments immediately downstream of hydropower dams. EPA approves all of these 

revisions for the reasons discussed below. 

The revisions at 38 M.R.S. § 464(9-A.D) and (9-A.E) (originally enacted as the last two 

paragraphs of § 464(9)), apply to existing hydropower impoundments classified as Great Ponds 

under 38 M.R.S. § 465-A. They reflect the legislature’s purpose of clarifying that the Class 

GPA criterion that “habitat must be characterized as natural” was not intended to apply to 

existing human-constructed great pond impoundments. Accordingly, § 464(9-A.D) requires 

such waters to, at a minimum, meet Class C habitat and aquatic life criteria, and § 464(9-A.E) 

requires that where the actual water quality in such impoundments attain any more stringent 

criteria required by the GPA classification, such water quality must be protected and 

maintained.

The revisions at 38 M.R.S. § 464(10) apply to existing hydropower impoundments managed 

under riverine classifications under 38 M.R.S. § 465. These reflect the legislature’s purpose of 

clarifying that Class A and B habitat and aquatic life uses and criteria defined as “natural” and 

“unimpaired” were intended to apply to free-flowing streams, and not to existing hydropower 

impoundments. Accordingly, § 464(10) provides that the Class A and B habitat characteristics 

 

18 EPA, Water Quality Standards Handbook - Chapter 5: General Policies, Section 5.1.1, subsection on mixing 

zone size, 2015 online version.
13

and aquatic life criteria are deemed to be met in existing hydropower impoundments as long as 

Class C aquatic life criteria are met. It further provides, however, that if reasonable changes 

can be made that would result in the improvement of habitat and aquatic life, such changes 

must be implemented and the resulting improved water quality must be achieved and 

maintained. In addition, where the actual water quality in such impoundments attain any more 

stringent criteria required by the applicable Class A or Class B criteria, that water quality must 

be protected and maintained.

The revisions at 38 M.R.S. § 464(11) apply to downstream stretches below two existing 

hydropower projects on the Kennebec River and two existing hydropower projects on the Saco 

River.19 These revisions also reflect the legislature’s purpose of clarifying that Class A habitat 

and aquatic life uses and criteria defined as “natural” were intended to apply to unaffected, 

free-flowing streams. Accordingly, § 464(11) provides that the Class A habitat characteristics 

and aquatic life criteria applicable to these segments are deemed to be met as long as Class C 

aquatic life criteria are met. 

The revisions at 38 M.R.S. § 464(4.H) allow hydropower projects constructed after 1991 to 

cause some change to the habitat and aquatic life of the project’s impoundment and the waters 

immediately downstream of and measurably affected by the project, so long as the habitat and 

aquatic life criteria of the applicable waters’ classifications under § 465 (standards for 

classifications of freshwaters), § 465-A (standards of classification for lakes and ponds), § 467 

(classifications of major river basins), and § 468 (standards of classification for minor 

drainages) are met. It specifically provides that it does not alter the habitat and aquatic life 

criteria under §§ 465 and 465-A. 

It is not clear that EPA ever approved 38 M.R.S. § 464(4.H), (9-A.D), (9-A.E), (10), and (11).

20

 

Therefore, EPA is today approving these provisions as applied to all waters in Maine. As EPA 

acknowledged in several letters to Maine in 1992 and 1993,21 the requirements to meet 

“natural” or “unimpaired” habitat and aquatic life characteristics are not necessarily appropriate 

for existing hydropower impoundments since they are, by their very nature, artificial. In its 

review of proposed legislation in 1992, EPA informed DEP that it was willing to accept, as 

satisfying federal UAA requirements, a single legislative finding that the “natural” and 

“unimpaired” criteria were not intended for existing impoundments to justify a change in the 

habitat and aquatic life criteria applicable to such impoundments, as long as Class C criteria at 

38 M.R.S. § 465(4.C) are required to be met. The Class C criteria allow some changes to 

aquatic life as long as the waters are of sufficient quality to support all species of indigenous 

 

19 These segments are not waters in Indian lands.

20 EPA disapproved § 464(9), contained in “Part A” of P.L. 1992 c. 813, on January 14, 1993. Section 464(9) 

included the original versions of current subsections (9-A.D) and (9-A.E)), but EPA’s disapproval did not relate to 

those provisions. EPA did not act at that time, or apparently at any later time, on other portions of the statute 

(including § 464(4.H) and (10)). On March 25, 1993, EPA approved a UAA that Maine prepared to address the 

January 14, 1993 disapproval and to support a subsequent amendment of § 464(9). It is not apparent that Maine 

ever submitted revised § 464(9) at any time before its May 2000 submission of all of its WQS to EPA’s repository. 

In 2005, § 464(9) was repealed and its provisions were relocated to new § 464(9-A), and entirely new provisions 

were also added to section 9-A. Maine submitted the new provisions to EPA by letter dated January 11, 2006, and 

EPA approved them by letter dated April 17, 2006, but not the relocated provisions from § 464(9).

21 Letters dated January 28, 1992, from Tonia Bandrowicz, EPA to Stephen Groves, DEP; February 4, 1992, from 

Tonia Bandrowicz, EPA to Stephen Groves, DEP ; November 25, 1992, from Ronald Manfredonia, EPA to 

Stephen Groves, DEP; and March 25, 1993, from Paul Keough, EPA to Dean Marriott, DEP.
14

fish and maintain the structure and function of the resident biological community. EPA 

concludes that the revisions at 38 M.R.S. § 464(9-A.D), (9-A.E), and (10) are consistent with 

EPA’s advice to DEP in 1992 and 1993; are reasonable in light of the legislature’s statement of 

original intent to apply “natural” and “unimpaired” to free-flowing waters and not artificially 

impounded waters; and by requiring attainment of at least Class C criteria (or better), are 

protective of existing and designated aquatic life uses. EPA concludes that the same reasoning 

applies to 38 M.R.S. § 464(11), for which the legislature provided a similar statement of 

original intent to apply the “natural” habitat and aquatic life criteria only to unaffected and freeflowing waters, and that by requiring attainment of at least Class C criteria, § 464(11) is 

protective of existing and designated aquatic life uses.

EPA concludes that 38 M.R.S. § 464(4.H) is protective of existing and designated uses because 

it specifies that any new (post-1992) hydropower project must meet the habitat and aquatic life 

criteria applicable to the water body’s classification. While this section allows some change to 

habitat and aquatic life, EPA interprets this change to be allowed only if consistent with the 

antidegradation policy in 38 M.R.S. § 464(4.F), since nothing in § 464(4.H) precludes the 

applicability of § 464(4.F). EPA’s approval is based on this interpretation.

2. 38 M.R.S. § 464(9-A.A) – EPA has reviewed 38 M.R.S. § 464(9-A.A), which establishes

habitat and aquatic life criteria for the impounded segment of the West Branch of the Penobscot 

River above the Ripogenus dam.22 In 1993, EPA disapproved the original version of this 

section (enacted in 1992 as § 464(9)), and Maine subsequently prepared a Use Attainability 

Analysis (“UAA”) to support the establishment of less stringent habitat and aquatic life criteria 

than would otherwise apply. EPA approved the Ripogenus UUA on March 25, 1993, 

consistent with 40 C.F.R. § 131.10(g)(4), based on the determination that the existence and 

operation of the dam precludes the attainment of Class C aquatic life and habitat criteria. EPA 

further found that it would not be possible to operate the dam in a manner that could attain the 

use, in part because the aquatic community that had evolved in the impoundment and 

downstream was an important fishery that would be placed at risk if dam operations were 

significantly changed. Maine subsequently revised § 464(9) consistent with the UAA, and then 

relocated it to new § 464(9-A.A) in 2005 (see footnote 19 for additional information). EPA has 

no record of having previously approved revised § 464(9). EPA approves the provision today 

in its current form of § 464(9-A.A), consistent with EPA’s approval of the UAA.

3. 38 M.R.S. § 636(8) – EPA has reviewed the revised WQS in 38 M.R.S. § 636(8), which 

requires that there be reasonable assurance that a proposed hydropower project will not violate 

applicable WQS, including antidegradation requirements, both in the impounded area and in 

waters downstream of the impoundment. It further directs DEP to reclassify impounded waters 

from a proposed project as GPA if certain showings are made, including that the project would 

comply with antidegradation requirements. 

Maine enacted this provision in response to EPA’s May 25, 1987 disapproval of prior 

legislation that automatically deemed such proposed impoundments to be GPA. EPA approved 

38 M.R.S. § 636(8) on December 20, 1990. EPA today approves this provision for waters in 

Indian lands, because it ensures that WQS, including antidegradation requirements, will be met 

both upstream and downstream of the proposed project, and it provides for reclassification to 

 

22 This segment is not a water in Indian lands.
15

GPA only if the DEP makes specific findings, including that antidegradation requirements will 

not be violated. EPA approves this provision with the understanding that the procedures for 

reclassification in 38 M.R.S. § 464(2), particularly regarding public participation, still apply to 

any reclassification pursuant to this section. This provision is protective of both designated and 

existing uses and consistent with the requirements of section 303 of the CWA and 40 C.F.R. 

part 131.

Downstream Protection for Class GPA Waters [38 M.R.S § 464(4.A(3))]

EPA’s review of the downstream protection provision in 38 M.R.S § 464(4.A(3)) is based on 

whether the provision is protective of designated uses. The provision prohibits discharges to 

tributaries of Class GPA waters that would impair the characteristics and designated uses of 

downstream GPA waters or cause an increase in the trophic state of those GPA waters. EPA 

approves this narrative protection of downstream waters because it is protective of designated 

uses in Class GPA waters and is consistent with the requirement in 40 C.F.R. § 131.10(b) that 

States take into consideration the water quality standards of downstream waters and ensure that 

its water quality standards provide for the attainment and maintenance of the water quality 

standards of downstream waters.

Criteria for Color, Taste, Turbidity, Toxicity, Radioactivity and Other Properties [38 

M.R.S § 464(4.A(4))]

EPA is approving the narrative criteria in 38 M.R.S § 464(4.A(4)) because the provision 

protects designated uses by prohibiting levels of these substances that would cause the waters 

to be unsuitable for the designated uses.

Criterion for pH in Estuarine and Marine Waters23 [38 M.R.S § 464(4.A(5))]

EPA’s review of the pH criterion for estuarine and marine waters in 38 M.R.S § 464(4.A(5)) is 

based on whether the criterion protects aquatic life uses in those waters. The criterion prohibits 

discharges that cause pH in estuarine and marine waters to fall outside of the 7.0 to 8.5 range. 

EPA’s current pH recommendation is included in the 1986 Gold Book, which recommends pH 

in the range of 6.5 to 8.5 to protect marine aquatic life24. Since Maine’s pH range for estuarine 

and marine waters is within that range, EPA finds that the pH criterion for estuarine and marine 

waters in 38 M.R.S § 464(4.A(5)) is protective of designates uses and approves it accordingly.

Criteria for Settled and Floating Substances [38 M.R.S. § 464(4.B)]

EPA’s review of Maine’s narrative criteria for settled and floating substances in 38 M.R.S. §

464(4.B) is based on whether the criteria are protective of designated uses. The provision 

states that “surface waters shall be free of settled substances which alter the physical or 

chemical nature of bottom material and of floating substances, except as naturally occur, which 

impair the characteristics and designated uses ascribed to their class.” EPA approves of the 

narrative criteria because they are explicitly protective of designated uses.

 

23 As discussed below, EPA is disapproving the pH criterion for freshwaters.

24 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, pH, May 1, 1986.
16

Instream Color Pollution Standard [38 M.R.S § 414-C(3)]

EPA approves the instream color pollution standard in 38 M.R.S § 414-C(3). This provision is 

protective of applicable designated uses because it defines a maximum total impact from 

discharges and thus provides an numeric threshold for waters to meet the narrative color criteria 

in 38 M.R.S. § 464(4.A.(4)) and is at least as protective as the EPA-recommended narrative 

criterion, which says that “waters shall be virtually free from substances producing 

objectionable color for aesthetic purposes.”

25

Dissolved Oxygen (“DO”) for Class AA and SA Waters, and Aquatic Life Criteria for 

Class A, AA, and SA Waters [38 M.R.S. § 465(1.B and 2.B) and 38 M.R.S. § 465-B(1.B)]

EPA's review of the narrative criteria for aquatic life for Class AA, A and SA waters (in 38 

M.R.S. § 465(1.B and 2.B) and § 465-B(1.B), respectively) and the narrative criteria for 

dissolved oxygen in Class AA and SA waters (in 38 M.R.S. § 465(1.B) and § 465-B(1.B), 

respectively) is based on whether the narrative criteria are protective of the designated uses of 

habitat for fish and other aquatic life. The criteria require that aquatic life for Class AA, A and 

SA waters and DO for Class AA and SA waters be as naturally occurs. Since the term “as 

naturally occurs” is defined in 38 M.R.S. § 466(2) to mean “conditions with essentially the 

same physical, chemical and biological characteristics as found in situations with similar 

habitats free of measurable effects of human activity,” EPA finds that these narrative criteria 

are protective of the aquatic life designated uses. Therefore EPA approves these criteria.

Narrative Aquatic Life Criteria for Class B, C, SB and SC Waters [38 M.R.S. § 465(3.C); 

38 M.R.S. § 465(4.C); 38 M.R.S. § 465-B(2.C); and 38 M.R.S. § 465-B(3.C)]

EPA’s review of the narrative criteria for aquatic life in Class B, C, SB and SC waters 

expressed in the first sentences of 38 M.R.S. § 465(3.C); 38 M.R.S. § 465(4.C); 38 M.R.S. § 

465-B(2.C); and 38 M.R.S. § 465-B(3.C), respectively, is based on whether the narrative 

criteria for aquatic life, expressed as a minimum condition remaining following the impact of 

discharges, support the designated uses for these water classifications. 

The designated uses for Class B and SB waters are similar: “habitat for fish and other aquatic 

life” and “habitat must be characterized as unimpaired” for Class B waters (at 38 M.R.S. § 

465(3.A)); and “habitat for fish and other estuarine and marine life” and “habitat characterized 

as unimpaired” for Class SB waters (at 38 M.R.S. § 465-B(2.A)). The narrative criteria to 

support these uses require that the waters be of sufficient quality to support all aquatic, 

estuarine, and marine species (as appropriate) indigenous to those waters without detrimental 

changes in the resident biological community. Maine defines “unimpaired” as “without 

diminished capacity to support aquatic life” at 38 M.R.S. § 466(11); “residential biological 

community” as “aquatic life expected to exist in a habitat which is free from the influence of 

the discharge of any pollutant” at 38 M.R.S. § 466(10); “indigenous” as “supported in a reach 

of water or known to have been supported according to historical records compiled by State 

and Federal agencies or published scientific literature” at 38 M.R.S. § 466(8); and “without 

detrimental changes to the resident biological community” as “no significant loss of species or 

 

25 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, Color, May 1, 1986.
17

excessive dominance by any species or group of species attributable to human activity” at 38 

M.R.S. § 466(12). Based on these definitions, EPA finds that the narrative criteria for Class B 

and SB waters in the first sentences of 38 M.R.S. § 465(3.C) and 38 M.R.S. § 465-B(2.C), 

respectively, do support the designated uses, including the designated use of unimpaired 

habitat, and EPA therefore approves these criteria.

The designated uses for Class C and SC waters are also similar: “habitat for fish and other 

aquatic life” at 38 M.R.S. §465(4.A) and “habitat for fish and other estuarine and marine life” 

at 38 M.R.S. § 465-B(3.A). The narrative criteria to support these uses require that “discharges 

to Class C waters may cause some changes to aquatic life, except that the receiving waters must 

be of sufficient quality to support all species of fish indigenous to the receiving waters and 

maintain the structure and function of the resident biological community.” Similarly, 

“discharges to Class SC waters may cause some changes to estuarine and marine life provided 

that the receiving waters are of sufficient quality to support all species of fish indigenous to the 

receiving waters and maintain the structure and function of the resident biological community.” 

Maine defines “community function” as “mechanisms of uptake, storage, and transfer of lifesustaining materials available to a biological community which determines the efficiency of use 

and the amount of export of the materials from the community” at 38 M.R.S. § 466(3), and 

“community structure” as the organization of a biological community based on numbers of 

individuals within different taxonomic groups and the proportion each taxonomic group 

represents of the total community” at 38 M.R.S. § 466(4). Based on these definitions, 

combined with the pertinent definitions in the previous paragraphs, EPA finds that the narrative 

criteria for Class C and SC waters in the first sentences of 38 M.R.S. § 465(4.C) and 38 M.R.S. 

§ 465-B(3.C), respectively, do support the designated uses, and EPA therefore approves these 

criteria.

Freshwater Temperature Criteria [DEP Rule Chapter 582(1)]

EPA’s review of Maine’s freshwater temperature criteria in DEP Rule Chapter 582(1) is based 

on whether the criteria protect designated aquatic life uses, including all life stages of 

indigenous and endangered species. The criteria include several components, all expressed as 

measured at a point outside a mixing zone established by the Board of Environmental 

Protection. The maximum allowable temperature increase (“delta T”) due to any discharge is 

3° F in the epilimnion of any lake or pond and 5° F in all other freshwaters. The ambient 

temperature due to discharges may not exceed 85° F, nor may it exceed EPA’s “national 

ambient water quality criteria established to protect all species of fish that are indigenous to the 

receiving waters.” Site specific criteria that are protective of indigenous species may also be 

developed. In addition, when ambient temperatures of the receiving water naturally exceed the 

maximum temperature criteria provided in Chapter 582(1), then the delta T is limited to 0.5° F.

EPA is approving the freshwater temperature criteria with the understanding that EPA’s 

recommended criteria will generally be the applicable criteria, because, with few exceptions, 

the maximum allowable temperature of 85° F is not protective of aquatic life uses, especially 

for many fish species that are indigenous to Maine waters. For example, the maximum 

allowable temperature of 85° F (29.4° C) is above temperatures which cause lethality in all life 
18

stages of endangered Atlantic salmon (including adult migration and smolt emigration).

26

Brook trout exhibit a similar temperature tolerance range, where temperatures above 24° C (75°

F) result in little to no growth.

27 EPA also finds that the delta T of 5° F may not adequately 

protect aquatic life in some waters, because, depending on the starting temperature, a 5° F 

temperature rise could result in temperatures that do not support various life stages of 

indigenous fish. For example, National Marine Fisheries Service, in providing input to EPA 

regarding the appropriateness of Maine’s freshwater temperature criteria related to the 

endangered Atlantic salmon, said the following about the delta T of 5° F:

We are particularly concerned that the five degree (Fahrenheit) limit...could increase 

the temperature of nearly every salmon river in the State of Maine above the survival 

thresholds for the freshwater life stages of Atlantic salmon.... Warming of rivers and 

streams during the spring and summer could increase temperatures outside of the 

optimal window for feeding and possibly outside the window for survival of fry and 

parr. Spring and summer warming may also inhibit adult migration or result in direct or 

indirect mortality. Warming of river temperatures in the spring would narrow the 

window of time that would allow successful passage of salmon smolts (the life stage 

where salmon are transitioning from freshwater to saltwater) that can only occur 

between 5 and 10° C. Any warming of river temperatures in the winter would have the 

effect of advancing development of eggs and alevins. If this occurs too quickly, they 

may use up available energy stores in the egg before food in the river is available. This 

too could have the effect of narrowing the window of a key development phase. Given 

the precarious state of salmon in the GOM DPS [Gulf of Maine Distinct Population 

Segment], anthropogenic changes in water temperatures that alter temperatures in a way 

that could interfere with Atlantic salmon migratory behaviors or embryonic and juvenile 

development may pose a significant risk to the species. 28

Therefore, EPA expects that the requirement in Maine’s freshwater temperature criteria that 

ensures that ambient temperatures do not exceed EPA’s national ambient water quality criteria

recommendations for all species of indigenous fish will typically supersede the default 

maximum 85° F temperature limit and 5° F delta T. EPA’s recommended temperature criteria 

provide a methodology for deriving temperature criteria on a site specific basis, depending on 

the species present or expected to be present and the pertinent life stages. EPA recommends, as 

described in the Gold Book,

29 that temperature criteria for any time of the year consist of two 

upper limiting temperatures for a specific location based on the important sensitive species and 

life stages found there during that time of year. One limit is a maximum temperature for short 

exposures that is time dependent and based on the results of experimental data for the sensitive 

species. The second value is a weekly average temperature which would vary seasonally and 

also be based on temperature sensitivity of the species present. Four species dependent options 

for deriving the weekly average temperature thresholds are provided in the Gold Book.

 

26 May 13, 2015 Letter from John K. Bullard, National Marine Fisheries Service, to Ralph Abele, EPA.

27 Picard C, Bozek M and Walter Momot, Effectiveness of Using Summer Thermal Indices to Classify and Protect 

Brook Trout Streams in Northern Ontario, North American Journal of Fisheries Management 23:206–215, 2003

28 May 13, 2015 Letter from John K. Bullard, National Marine Fisheries Service, to Ralph Abele, EPA, page 5.

29 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, Temperature, May 1, 1986.
19

EPA approves DEP Rule Chapter 582(1) because it requires that temperatures in the receiving 

waters not exceed EPA recommended criteria for indigenous species, which include 

temperature sensitive species such as brook trout and the endangered Atlantic salmon. EPA’s 

recommended criteria are based on sound science and provide a methodology for deriving 

ambient temperatures that are protective of such species. By incorporating EPA’s 

recommended criteria, Maine’s criteria are protective of aquatic life uses. 

EPA approves the criteria as applicable to freshwaters, whether or not there is a mixing zone. 

If the Board does establish a mixing zone, then compliance for dischargers is to be measured at 

the edge of the mixing zone. As a result of EPA’s disapproval today of Maine’s mixing zone 

policy, discussed below, EPA expects that Maine will revise its policy and ensure that 

subsequently established mixing zones, including for temperature, will be protective of all uses, 

including aquatic life uses for indigenous species such as the endangered Atlantic salmon.

DO Criteria for Class B, SB and SC Waters [38 M.R.S. § 465(3.B); 38 M.R.S. § 465-

B(2.B); and 38 M.R.S. § 465-B(3.B)]

EPA’s review of Maine’s DO criteria for aquatic life for Class B fresh waters in 38 M.R.S. § 

465(3.B), is based on whether the criteria protect aquatic life uses, including consideration of 

EPA’s National Recommended Water Quality Criteria published pursuant to Section 304(a) of 

the CWA. The criteria require that DO content be at least 7 mg/l or 75% of saturation, 

whichever is higher, from May 15th to September 30th. From October 1st to May 14th, in order 

to ensure spawning and egg incubation of indigenous fish species, the 7-day mean DO content 

must be at least 9.5 mg/l and the 1-day minimum DO content must be at least 8 mg/l in 

identified fish spawning areas. The spawning and egg incubation criteria are consistent with 

EPA’s Quality Criteria for Water 1986 (“Gold Book”)30 recommendations for protection of 

early life stages of coldwater species. The minimum DO criterion of 7 mg/l year-round for nonspawning areas and during the summer months for spawning areas, is at least as protective as 

EPA’s recommendations for other life stages of coldwater species and all life stages of 

warmwater species (3 to 6.5 mg/l). EPA approves the DO criteria for Class B waters because 

they are based on sound science and protective of designated uses for the reasons provided in 

EPA’s Gold Book. 

EPA's review of the DO aquatic life criteria in 38 M.R.S. § 465-B(2.B) (for Class SB estuarine 

and marine waters, DO at least 85% saturation); and § 465-B(3.B) (for Class SC waters, DO at 

least 70 % saturation) is similarly based on whether the criteria protect aquatic life uses, 

including consideration of EPA’s National Recommended Water Quality Criteria published 

pursuant to Section 304(a) of the CWA and DO criteria for Canadian marine waters. 

EPA’s current recommendations for saltwater DO criteria31 of 4.8 mg/l for chronic exposure 

and 2.3 mg/l for acute exposure were developed to protect aquatic life in east coast Atlantic and 

estuarine waters in the Virginia Province (ranging from Cape Cod, Massachusetts to Cape 

Hattaras, North Carolina). These values are not directly comparable to Maine’s criteria, which 

are expressed as percent saturation rather than as a DO concentration. However, it is possible 

 

30 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, Dissolved Oxygen, May 1, 1986.

31 EPA, Ambient Aquatic Life Water Quality Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape 

Hatteras, EPA-822-R-00-012, November 2000.
20

to compare EPA’s DO recommendations for the Virginia Province to Maine criteria for coastal 

waters by accounting for the differences in ambient temperatures. During the critical summer 

period (May 15th through September 30th), ambient monthly average coastal temperatures range 

up to 52° F (11° C) at the National Oceanic and Atmospheric Administration’s (“NOAA”) 

ambient water temperature monitoring location near Eastport, Maine. Using the 52° F ambient 

temperature and a DO-to-percent-saturation conversion table,

32 EPA’s recommended minimum 

values for the Virginia Province translate to 32% saturation for chronic exposure and 21% 

saturation for acute exposure, both well below Maine’s criteria of 70% and 85% saturation. 

In evaluating Maine’s criteria, EPA also reviewed the Canadian Water Quality Guidelines for 

the Protection of Aquatic Life for marine dissolved oxygen.33 Canadian guidelines recommend 

a minimum concentration of DO in marine and estuarine waters of 8.0 mg/l, or at 11° C, 73% 

DO saturation34, within the range of Maine’s criteria of 85% and 70% saturation for Class SB 

and SC waters respectively.

EPA approves Maine’s DO criteria for SB and SC waters because they are protective of aquatic 

life uses in estuarine and marine waters.

Identification of Spawning Areas and Applicable DO Criteria [DEP Rule Chapter 585 

and the last two sentences of 38 M.R.S. § 465(4.B)]

EPA’s review of DEP Rule Chapter 585, which specifies how fish spawning areas in Class B 

waters and salmonid spawning areas in Class C waters are to be identified and the applicable 

DO criteria for such areas, is based on whether the requirements are supportive of aquatic life 

uses in Class B and C waters.

DO criteria set forth in 38 M.R.S. § 465(3.B) and (4.B) for Class B and C waters, respectively,

include special numeric DO criteria for October 1 - May 14 in all spawning areas in Class B 

waters and narrative DO criteria in salmonid spawning areas in Class C waters, and § 465(4.B) 

further directs the Board to adopt rules for designation of spawning areas. The identification of 

spawning areas in these waters is critical to the protection of the use. In accordance with 

Chapter 585, prior to licensing or relicensing any wastewater discharge that may affect DO, 

DEP is required to request that the Maine Department of Inland Fisheries and Wildlife (DFW) 

identify existing or potential fish spawning areas. As the state agency with responsibility for 

managing fisheries, DFW has the resources and expertise, such as fisheries biologists, habitat 

inventories, and river reports, to make such identifications. 

In addition, Chapter 585(1) includes the DO requirements that are specified in § 465(3.B) for 

spawning areas in Class B waters; and Chapter 585(3) specifies that in designated spawning 

areas in Class C waters, DO criteria shall not fall below the EPA recommended criteria for 

spawning for the period October 1- May 14. If levels of DO fall below EPA’s recommended 

criteria, then corrective action is required or a UAA must be conducted,

 

32 http://www.usawaterquality.org/volunteer/pdf/Special/DOConvTbl.pdf

33 Canadian Council of Ministers of the Environment, Canadian Water Quality Guidelines for the Protection of 

Aquatic Life, Dissolved Oxygen (Marine), Excerpt from Publication No. 1299; ISBN 1-896997-34-11999.

34 Conversion to % saturation using conversion table at 

http://www.usawaterquality.org/volunteer/pdf/Special/DOConvTbl.pdf
21

EPA approves the last two sentences of 38 M.R.S. § 465(4.B) related to the adoption of rules 

governing designation of spawning areas, and all of Rule Chapter 585. EPA approves the 

requirements for spawning area identification in Chapter 585 because this coordination is 

necessary to ensure that DO criteria are implemented in a manner that protects aquatic species 

with reproductive cycles that are sensitive to low DO levels. EPA approves the DO criteria for 

Class B spawning areas for the reasons discussed above related to 38 M.R.S. § 465(3.B), and

approves the DO criteria for Class C spawning areas because they require DO to be at least as 

high as EPA’s recommended criteria, which are based on sound science and are protective of 

the designated use.

Shellfishing Bacteria Criteria for Class SB and SC Waters [38 M.R.S. § 465-B(2.B and 

3.B)]

EPA’s review of Maine’s bacteria criteria for the protection of shellfishing uses in Class SB 

and SC waters (in 38 M.R.S. § 465-B(2.B and 3.B), respectively) is based on whether the 

criteria are protective of the “propagation and harvesting of shellfish” use in Class SB waters 

and the “propagation and restricted harvesting of shellfish” use in Class SC waters. 

The shellfishing criteria for Class SB and SC waters are identical: “The numbers of total 

coliform bacteria or other specified indicator organisms in samples representative of the waters 

in shellfish harvesting areas may not exceed the criteria recommended under the National 

Shellfish Sanitation Program [(“NSSP”)], United States Food and Drug Administration.” Since 

this reference to the NSSP recommendations was enacted in 1986,

35 the NSSP 

recommendations in effect in 1986 are the applicable criteria for Class SA and SB waters. 

NSSP’s bacteria recommendations for unrestricted (as for Class SB waters) and restricted (as 

for Class SC waters) harvesting of shellfish have not changed since 1986.36, EPA’s 

recommendation for shellfishing bacteria criteria, provided in the 1986 Gold Book,

37 are the 

same as the NSSP criteria for unrestricted harvesting of shellfish. EPA does not have a bacteria 

criteria recommendation for restricted harvesting of shellfish.

EPA approves the shellfishing bacteria criteria for Class SB and SC waters in 38 M.R.S. § 465-

B(2.B and 3.B), because they reflect the current NSSP and EPA recommendations and are 

therefore protective of the designated uses. While we approve these provisions, we recommend 

that Maine adopt the NSSP numeric shellfishing bacteria criteria directly into WQS rather than 

by reference to undated recommendations. This would ensure that the requirements are clear 

on their face, and would avoid confusion if NSSP recommendations change in the future.

Compliance Schedule [38 M.R.S. § 414-A(2)]

EPA approves 38 M.R.S. § 414-A(2), which authorizes the use of compliance schedules in 

discharge licenses to meet final effluent limitations based on a water quality standard adopted 

 

35 "An Act to Amend the Classification System for Maine Waters and Change the Classification System of Certain 

Waters," Maine Public Laws, l12th Legislature, Chapter 698 (the “Reclassification Act").

36 See National Shellfish Sanitation Program Manual of Operations Part I, Sanitation of Shellfish 

Growing Areas, revised 1986; and NSSP, Guide for the Control of Molluscan Shellfish, 2013 Revision.

37 EPA Quality Criteria for Water 1986, EPA 440/5-86-001, Bacteria, May 1, 1986
22

after July 1, 1977. The purpose of such a schedule is, where appropriate, to afford a permittee 

adequate time to comply with permit requirements that are based on new or revised water 

quality standards. EPA approves this provision because it is consistent with EPA’s 

interpretation of the circumstances under which such compliance schedules may be provided 

consistent with the federal Clean Water Act.

Toxic Substances [38 M.R.S. § 420(2) and (2.A) through (2.G)] 

EPA’s review of the WQS provisions in 38 M.R.S. § 420(2) and (2.A) through (2.G), which 

provide direction to the Board of Environmental Protection (“Board”) regarding the 

establishment of water quality criteria for toxic substances, is based on whether the resulting 

criteria would be protective of designated uses.

The introductory text in 38 M.R.S. § 420(2) generally identifies the scope of toxic substances to 

be regulated and defines the term “toxic substance.” The provision requires that the Board take 

into consideration the toxicity, persistence and degradability of the substance as well as the 

sensitivity of organisms, including humans, potentially affected by the substance, either alone 

or in combination with substances already present. The definition of “toxic substance” is 

generally consistent with the CWA’s definition of “toxic substances” in CWA § 502(13). EPA 

approves the introductory text in 38 M.R.S. § 420(2) because it is consistent with the 

requirements in 40 C.F.R. § 131.12(a)(2), which require states to adopt water quality criteria 

for toxic pollutants and to protect designated uses, and because the provisions explicitly require 

that sensitive organisms be protected.

The provisions in 38 M.R.S. § 420(2.A) through (2.G) instruct and authorize the Board of 

Environmental Protection to adopt statewide criteria for toxic substances that are consistent 

with EPA recommendations or to adopt site-specific criteria or alternative statewide criteria 

that are based on sound scientific rationale and protective of the most sensitive designated uses. 

EPA approves these provisions (except for the clause related to naturally occurring toxic 

substances in § 420(2.A), which EPA is separately partially approving and partially 

disapproving, as discussed on pages 7 and 27-28, respectively) because they are consistent with 

the requirements in 40 C.F.R. § 131.11 for state adoption of water quality criteria.

Prohibitions and Exceptions to Prohibitions on Discharges to Class AA and Class SA 

Waters [38 M.R.S. § 465(1.C); 38 M.R.S. § 465(1.C.(2)); 38 M.R.S. § 465(1.C.(3)); 38 

M.R.S. § 465(1.C.(4)); 38 M.R.S. § 465(1.C.(5)); 38 M.R.S. § 465-B(1.C.(2)); 38 M.R.S. § 

465-B(1.C); 38 M.R.S. § 465-B(1.C.(3)); and 38 M.R.S. § 465-B(1.C.(4))]

In EPA’s February 2, 2015 decision letter related to Maine WQS revisions submitted to EPA 

between 2004 and 2014, EPA identified, among others, the following statutory revisions that 

EPA concluded were not WQS and therefore EPA did not act on them in that decision letter: 38 

M.R.S. § 465(1.C.(2)); 38 M.R.S. § 465(1.C.(3)); 38 M.R.S. § 465(1.C.(4)); 38 M.R.S. § 

465(1.C.(5)); 38 M.R.S. § 465-B(1.C.(2)); and 38 M.R.S. § 465-B(1.C.(4)). EPA now 

recognizes that this characterization was in error. All of these revisions allow exceptions from 

the general prohibitions on direct discharges to Class AA and SA waters in 38 M.R.S. § 

465(1.C) and § 465-B(1.C), respectively. Class AA and SA waters are specifically identified as 

outstanding national resource waters (“ONRWs”) in 38 MRS § 464(4.F.(2)) and are therefore 

afforded the highest (Tier 3) protection under federal and state antidegradation policies. The 
23

exceptions to the prohibitions on discharges that would otherwise apply to these ONRWs are 

integrally related to the extent of Tier 3 antidegradation protection afforded to these waters. 

Consequently, EPA has concluded that they are WQS revisions. EPA today approves these 

provisions, along with the pre-2003 general prohibitions in 38 M.R.S. § 465(1.C) and § 465-

B(1.C) and an additional revision at 38 M.R.S. § 465-B(1.C.(3)), having determined that they 

are consistent with the federal antidegradation requirement at 40 C.F.R. § 131.12(a)(3) for the 

reasons discussed below.

38

 It is important to note that any discharges authorized under these 

provisions must also meet all other applicable water quality standards.

EPA’s antidegradation policy requires the quality of ONRWs to be “maintained and protected.”

40 C.F.R. § 131.12(a)(3). EPA interprets this requirement to mean that there shall be no new or 

increased discharges to ONRWs or their tributaries that would lower water quality, with some 

exception for limited activities that result in temporary and short-term changes in water quality 

(Water Quality Standards Handbook: Second Edition, EPA-823-B-94-005a, August 1994, at 

section 4.7). 

EPA approves the general prohibitions on direct discharges to Class AA and SA waters in 38 

M.R.S. § 465(1.C) and § 465-B(1.C), respectively, because they clearly afford protection of 

ONRWs consistent with the antidegradation policy. 

EPA approves the revision at 38 M.R.S. § 465(1.C.(2)), which allows discharges approved by 

DEP to aid in wild Atlantic salmon restoration, for the same reasons stated in EPA’s January 

25, 2005 approval of the revisions for state waters outside Indian lands. Specifically, the 

discharge provision is not an authorization to lower water quality. Rather, the discharges must 

be for the express purpose of assisting in the restoration of endangered Atlantic salmon by 

restoring water quality that has been degraded by anthropogenic activity. This is consistent 

with 40 C.F.R. § 131.12(a)(3). Further, the intent to restore natural ambient water chemistry to 

aid in the restoration of endangered salmon is consistent with the overall objective of the CWA 

at 101(a).

EPA approves the revision at 38 M.R.S. § 465(1.C.(3)), which allows aquatic pesticide or 

chemical discharges approved by DEP for invasive species control. EPA finds that since such 

discharges are, by their nature, short-term and temporary, and are for the express purpose of 

restoring biological communities affected by invasive species, the provision will not result in a 

lowering of water quality of ONRWs and therefore is consistent with 40 C.F.R. § 131.12(a)(3). 

EPA approves the revisions at 38 M.R.S. § 465(1.C.(4)) and 38 M.R.S. § 465-B(1.C.(2)), 

which allow licensed discharges of aquatic pesticides approved by DEP for the control of 

mosquito-borne diseases, for the same reasons stated in EPA’s August 19, 2009 approval of the 

revisions for state waters outside Indian lands. EPA finds that since the discharges of aquatic 

pesticides for mosquito control are, by their nature, short-term and temporary, and will use 

methods and materials that are protective of non-target species, the provisions will not result in 

a lowering of water quality and are consistent with 40 C.F.R. § 131.12(a)(3).

 

38 EPA addresses two additional WQS revisions at 38 M.R.S. § 465(1.C.(1)) and 38 M.R.S. § 465-B(1.C.(1), 

which allow stormwater discharges to Class AA and SA waters, respectively, in the disapproval section below. 
24

EPA approves the revision at 38 M.R.S. § 465-B(1.C.(3)), which allows overboard discharges 

licensed prior to January 1, 1986. Because this provision relates to discharges that existed 

before 1986, it does not authorize new or increased discharges to Class SA waters and therefore 

will not result in a future lowering of water quality and is consistent with 40 C.F.R. § 

131.12(a)(3).

EPA approves the revisions at 38 M.R.S. § 465(1.C.(5)) and 38 M.R.S. § 465-B(1.C.(4)),

which allow the discharge of pesticides approved by DEP that are unintended and the incidental 

result of spraying of pesticides as long as they are applied consistent with federal labeling 

restrictions and in compliance with state pesticide rules and best management practices. 

Because such discharges would be short term and temporary, and in compliance with federal 

and state pesticide requirements, EPA concludes that these provisions will not result in a 

lowering of water quality and are thus consistent with 40 C.F.R. § 131.12(a)(3). 

Supporting Discussion of Disapprovals

Waiver or Modification of Protection and Improvement Laws [38 M.R.S. § 363-D]

Under 38 M.R.S. § 363-D, the DEP Commissioner or her designee may waive or modify any 

provision of Chapter 3 (Protection and Improvement of Waters), which includes water quality 

standards, to assist in any oil spill response activity conducted in accordance with the national 

or state contingency plans, or as otherwise directed by the federal on-scene coordinator or the 

Commissioner or her designee. 

Waivers or modifications of WQS that would have the effect of removing a designated use or 

creating a subcategory of use, including waiving or modifying criteria necessary to support the 

use, may occur under the Clean Water Act but only in accordance with 40 C.F.R. § 131.10(g) 

(which, among other things, requires a use attainability analysis). Before taking such action, 

states must provide public notice and an opportunity for a public hearing, and revised WQS are 

subject to EPA review and approval. Because 38 M.R.S. § 363-D does not contain any of these 

requirements, it is not consistent with minimum federal requirements. Therefore EPA is 

disapproving 38 M.R.S. § 363-D as it relates to water quality standards.39 EPA has no record 

of ever having previously acted to approve or disapprove this statute for any waters in Maine, 

so this disapproval applies to all waters in the State. Because 38 M.R.S. § 363-D was 

submitted to EPA before May 30, 2000, it will remain applicable for Clean Water Act purposes 

in state waters outside Indian lands until either EPA approves a revision promulgated by Maine 

or EPA promulgates a revision. See 40 C.F.R. § 131.21(c).

Maine may remedy this disapproval either by specifying in the statute that it does not apply to 

water quality standards, or by including requirements that must be satisfied before any waiver 

 

39 EPA regulations, at 40 C.F.R. § 122.3(d), provide a limited exception from the need to get an NPDES permit 

and, indirectly, to comply with water quality standards, for “any discharge in compliance with the instructions of 

an On-Scene Coordinator pursuant to 40 CFR part 300 (The National Oil and Hazardous Substances Pollution 

Contingency Plan) or 33 CFR 153.10(e) (Pollution by Oil and Hazardous Substances).” Maine has a similar 

permitting exemption at 38 M.R.S. § 413(2-G.B). By contrast, 38 M.R.S. § 363-D does not limit the waiver to 

discharges conducted in compliance with the instructions of the federal On-Scene Coordinator, nor is it limited to 

discharges associated with removal efforts at the scene of the oil spill, which is the purpose of EPA’s regulation. 
25

or modification of WQS takes effect under the statute, including public participation, use 

attainability analysis, and EPA review and approval.

Dissolved Oxygen (“DO”) Aquatic Life Criteria for Class A Fresh Waters [38 M.R.S. § 

465(2.B)]

EPA's review of the DO criterion for aquatic life in 38 M.R.S. § 465(2.B) for Class A fresh 

waters is based on whether the criterion is protective of aquatic life uses, including all life 

stages of indigenous species. The criterion requires a minimum of 7 mg/l DO year round. 

EPA’s Gold Book recommends criteria for DO that are protective of coldwater and warmwater 

species at all life stages. These include freshwater DO criteria of at least 9.5 mg/l as a 7-day 

mean and at least 8 mg/l as a 1-day minimum to protect early life stages of coldwater species, 

including salmonids, and 3 to 6.5 mg/l for adult coldwater species and all life stages of warm 

water species. Maine’s DO criterion for Class A freshwaters is protective of all life stages of 

warmwater species and adult coldwater species, but is not high enough to protect the early life 

stages of coldwater species. 

In 1986, EPA declined to approve Maine’s Class A criterion and requested that Maine adopt 

criteria for Class A waters that are protective of salmonid spawning, as had been done in Class 

B waters.40 EPA reminded DEP of this request again in 1988.41 So far, Maine has not 

remedied this deficiency in the DO criteria for Class A fresh waters. 

Because the DO criterion for aquatic life in 38 M.R.S. § 465(2.B) does not protect early life 

stages of coldwater species and, therefore, the full aquatic life designated use, EPA is 

disapproving the criterion. This disapproval applies in all waters of Maine, including waters in 

Indian lands, because EPA never previously acted on the criterion for state waters. Because 38 

M.R.S. § 465(2.B) was submitted to EPA before May 30, 2000, it will remain applicable for 

Clean Water Act purposes in state waters outside Indian lands until either EPA approves a 

revision promulgated by Maine or EPA promulgates a revision. See 40 C.F.R. § 131.21(c). 

Maine may remedy this disapproval by adopting DO criteria for Class A fresh waters that are 

protective of all life stages of indigenous aquatic life.

Mixing Zones [38 M.R.S. § 451]

Maine’s mixing zone policy, which is set forth in 38 M.R.S. § 451, allows the Commissioner to 

establish mixing zones that would allow the “reasonable” opportunity for dilution or mixture of 

pollutants before the receiving waters would be evaluated for WQS compliance.

States have the discretion to adopt mixing zone policies into their WQS, subject to EPA review 

and approval. 40 C.F.R. § 131.13. EPA’s mixing zone guidance explains that a mixing zone is 

a limited area or volume of water where initial dilution of a discharge takes place, and where 

certain numeric criteria may be exceeded, so long as the designated uses of the waterbody as a 

whole are protected.42 While mixing zones serve to dilute concentrations of pollutants in 

effluent discharges, they also allow increases in the mass loading of the pollutant to the 

 

40 July 16, 1986, Letter from Michael R. Deland, EPA to Kenneth C. Young, DEP, page 3.

41 November 3, 1988, Letter from David A. Fierra, EPA to Stephen W. Groves, DEP, page 4.

42 EPA, Water Quality Standards Handbook – Section 5: General Policies, Section 5.1, 2015 online version.
26

waterbody (more so than would occur if no mixing zone were allowed). Therefore, if not 

applied appropriately, a mixing zone could adversely affect mobile species passing through the 

mixing zone as well as less mobile species (e.g., benthic communities) in the immediate 

vicinity of the discharge. Because of these and other factors, mixing zones should be applied 

carefully so that they do not result in impairment of the designated use of the waterbody as a 

whole or impede progress toward the CWA goals of restoring and maintaining the physical, 

chemical, and biological integrity of the Nation’s waters. 43

EPA’s guidance includes specific recommendations that a state’s mixing zone policy should 

include to ensure the protection of uses. Among other things, mixing zone policies should 

ensure that mixing zones do not impair the designated uses of the water body as a whole; that 

pollutant concentrations in the mixing zone are not lethal to organisms passing through and do 

not cause significant human health risks; and that mixing zones do not endanger critical areas 

such as breeding or spawning grounds, drinking water intakes and sources, shellfish beds, or 

endangered or threatened species habitat.44,45 Maine’s mixing zone law does not contain any of 

these or other scientifically sound safeguards to ensure the protection of designated uses. The 

only specific statutory limitation on mixing zones in Maine’s mixing zone policy is that they be 

“reasonable.”

In 1985, EPA requested DEP to develop a mixing zone policy consistent with EPA’s 

guidance.

46 DEP’s response did not include agreement to develop a written policy or rule, 

saying instead that “Decisions regarding mixing zones considers [sic] the factors in E.P.A.’s 

‘Water Quality Standards Handbook,’ Chapter 2.”47 On October 29, 1998, DEP acknowledged 

that EPA had, several years previously, asked Maine to develop a mixing zone rule.

48

 To 

EPA’s knowledge, no rule was ever promulgated or submitted to EPA.49 

EPA is disapproving 38 M.R.S § 451 for waters in Indian lands because it does not ensure that 

mixing zones will protect designated uses. Maine may remedy this disapproval by revising the 

statute or promulgating a regulation which contains explicit conditions on the scope and extent 

of mixing zones adequate to protect designated uses. EPA recommends that any revision 

extend to all waters in Maine, not just waters in Indian lands.

pH Criterion for Fresh Waters [38 M.R.S. § 464(4.A(5))]

EPA’s review of Maine’s pH criterion in 38 M.R.S. § 464(4.A(5)) for fresh waters is based on 

whether the criterion is protective of aquatic life uses. The criterion prohibits discharges from 

 

43 Id.

44 Id., Section 5.1.1

45 EPA, Technical Support Document For Water Quality-based Toxics Control, EPA/505/2-90-001, March 1991, 

pages 70-71.

46 Letters dated February 20, 1985 from Michael Deland, EPA to Henry Warren, Maine DEP; and March 7, 1985 

from David Fierra, EPA to Stephen Groves, DEP.

47 April 1, 1985, Letter from Stephen W. Groves, DEP to Michael R. Deland, EPA, Attachment page 2.

48 October 29, 1998, Email from Barry Mower, DEP to William Beckwith, EPA

49 EPA is today approving for tribal waters the zone of passage provision in DEP Rule Chapter 581(5). While 

related to the establishment of a mixing zone, it does not itself constitute a mixing zone policy or provide the 

necessary protection of designated uses.
27

causing pH to fall outside of the 6.0 to 8.5 range. EPA’s recommended criterion for pH in 

fresh waters, which has been unchanged since 1976, specifies that pH be in the range from 6.5 

to 9.0 to protect freshwater aquatic life.50, 51

In September of 1976, EPA recommended that Maine adopt pH criteria consistent with EPA’s 

1976 Water Quality Criteria.

52

 At the time, Maine’s freshwater pH criterion, which had been 

part of Maine’s WQS since at least 1972, was already 6.0 to 8.5 for fresh waters.53 States may 

adopt, and EPA may approve, statewide or site specific criteria that are less stringent than

EPA’s recommendations if there is a scientific basis that shows that a less stringent criteria is 

protective of designated the designated uses. However, EPA is not aware of correspondence or 

other documentation in our records indicating that such a scientific basis has ever been 

provided to justify Maine’s pH criterion for fresh waters.

EPA disapproves Maine’s pH criteria in 38 M.R.S. § 464(4.A(5)) for fresh waters in Indian 

lands because the low end of the pH range (6.0) is below EPA’s recommended criterion of 6.5 

for the low end of the pH range, and it is not protective of aquatic life uses. Maine may remedy 

this disapproval by adopting criteria that are consistent with EPA’s recommendations or by 

demonstrating, based on sound scientific rationale, why pH in the range of 6.0 to 6.5 is 

protective of freshwater aquatic life uses. EPA recommends that any revision extend to all

waters in Maine, not just waters in Indian lands.

Natural Conditions Clauses as They Apply to Human Health Criteria [38 M.R.S § 

464(4.C) and 38 M.R.S. § 420(2.A)]

EPA’s review of Maine’s natural conditions clauses at 38 M.R.S § 464(4.C) and § 420(2.A) as 

they apply to human health criteria is based on whether the clauses protect designated human 

uses. The clause in 38 M.R.S § 464(4.C) says that, “Where natural conditions, including but 

not limited to, marshes bogs and abnormal concentrations of wildlife cause the dissolved 

oxygen criteria or other water quality criteria to fall below the minimum standards...those 

waters shall not be considered to be failing to attain their classification because of those natural 

conditions.” The clause in 38 M.R.S. § 420(2.A) says, “Except as naturally occurs or as 

provided in paragraphs B and C, the board shall regulate toxic substances in the surface waters 

of the State at the levels set forth in federal water quality criteria as established by the United 

States Environmental Protection Agency pursuant to the Federal Water Pollution Control 

Act....” 

These provisions are not consistent with EPA’s interpretation of the relationship between 

natural conditions and the protection of designated human health uses, which is articulated in 

EPA's November 1997 guidance entitled Establishing Site Specific Aquatic Life Criteria Equal 

to Natural Background.

54

 As discussed above in EPA’s approval of these natural conditions 

clauses as they relate to aquatic life, EPA recognizes that there may be naturally occurring 

concentrations of pollutants which exceed the national criteria published under section 304(a) 

 

50 EPA, Quality Criteria for Water, July 1976, page 178. 

51 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, pH, May 1, 1986.

52 September 23, 1976, Letter from Kenneth L. Johnson, EPA, to William R. Adams, Jr., DEP 

53 EPA and DEP, Water Quality Standards Summary, 1972, pages I-4 to I-5.

54 Davies, Tudor, EPA. Establishing Site Specific Aquatic Life Criteria Equal to Natural Background, November 

5, 1997.
28

of the CWA that are still protective of aquatic life. However, in contrast with aquatic life uses, 

a natural level of a naturally occurring pollutant does not necessarily protect designated human 

uses. Naturally occurring levels of a pollutant are assumed to protect aquatic life species that 

have naturally developed in the affected waters. However, human health does not adapt to 

higher ambient pollutant levels, even if they are naturally caused. Consequently, the same 

assumptions of protectiveness cannot be made with regard to designated uses that affect human 

health (e.g., people eating fish or shellfish from Maine waters, and recreating in Maine waters). 

For this reason, EPA’s 1997 guidance also states that where the natural background 

concentration exceeds the state-adopted human health criterion, at a minimum, states should reevaluate the human health use designation.

55

Therefore, EPA disapproves the natural conditions clauses at 38 M.R.S §464(4.C) and § 

420(2.A) for waters in Indian lands as they apply to criteria that protect human health because 

the application of these provisions fails to protect designated human health uses as required by 

the CWA and federal water quality standards regulations at 40 C.F.R. § 131.11(a). Maine may 

remedy this disapproval by clarifying in statute, or, if appropriate, in a rule, that these

provisions do not apply to human health criteria. EPA recommends that any revisions extend 

to all waters in Maine, not just waters in Indian lands. If there are naturally occurring 

pollutants which exceed Maine’s criteria to protect human health, Maine may revise its WQS 

on a site-specific basis to remove or modify a use, in accordance with the procedures of 40 

C.F.R. § 131.10(g) and 38 M.R.S. § 464(2-A).

EPA is aware of the error made in our approvals of similar provisions in DEP Rule Chapter 

584(2) and (3), which allow for naturally occurring pollutants which impart toxicity. These

provisions were approved by EPA in state waters in 200756 and in waters in Indian lands in 

2015.

57

 We recommend that at the same time that Maine revises the natural conditions clauses

in 38 M.R.S §464(4.C) and § 420(2.A) to pertain only to aquatic life uses, Maine also remedy 

the corresponding clauses currently in DEP Rule Chapter 584 for toxic substances.

Narrative Bacteria Criteria for Class AA, A, and SA Waters [38 M.R.S. § 465 (1.B and 

2.B) and 38 M.R.S. § 465-B(1.B)]

EPA’s review of Maine’s narrative bacteria criteria for Class AA, A, and SA waters in 38 

M.R.S. § 465(1.B and 2.B) and 38 M.R.S. § 465-B(1.B) is based on whether the criteria are 

protective of recreational uses and, in SA waters, also shellfishing uses. The criteria specify

that bacteria content of these waters shall be “as naturally occurs.”

EPA recognizes that the intent of these criteria, similar to DO and aquatic life criteria for these 

waters, is to reflect conditions unaffected by human activity. However, in the case of bacteria, 

human pathogens can result from naturally occurring sources such as wild animals. Therefore 

there is potential human health risk from recreational and shellfishing exposure to bacteria in 

naturally occurring, wild animal-impacted waters (2012 Recreational Water Quality Criteria,

see section 3.5.1-2). This concern underlies EPA’s disapproval on March 16, 2015 of Maine’s 

recreational bacteria criteria as applied to waters in Indian lands, because the criteria did not 

 

55 Id, page 3.

56 July 7, 2007, Letter from Linda M. Murphy, EPA to David P. Littell, DEP, page 1.

57 February 2, 2015, Letter from H. Curtis Spalding, EPA to Patricia W. Aho, DEP, page 3.
29

address bacteria from wild animal sources. Similarly, EPA disapproves the narrative criteria, 

“as naturally occurs” for bacteria in Class AA, A and SA waters in Indian lands, because they

do not adequately protect recreation in and on the waters in Class AA, A, and SA waters, and 

propagation and harvesting of shellfish in Class SA waters.

To address this disapproval, EPA recommends that Maine adopt bacteria criteria for Class A, 

AA and SA waters in Indian lands to support recreational and shellfishing uses, including 

EPA’s 2012 recommendations for recreational criteria58 and EPA’s 1986 Gold Book 

recommendations for shellfishing59 or the NSSP’s most recent recommendations for shellfish 

harvesting without depuration.

60 EPA also recommends that any revision extend to all waters 

in Maine, not just waters in Indian lands. 

Exceptions to Prohibitions on Discharges to Class AA and Class SA Waters [38 M.R.S. § 

465(1.C.(1)) and 38 M.R.S. § 465-B(1.C.(1))]

EPA’s review of 38 M.R.S. § 465(1.C.(1)) and 38 M.R.S. § 465-B(1.C.(1)), which allow an 

exception from the general prohibitions on direct discharges to Class AA and SA waters, 

respectively, for stormwater discharges that comply with state and local requirements, is based 

on whether they are consistent with the federal antidegradation requirement at 40 C.F.R. § 

131.12(a)(3).

Class AA and SA waters are specifically identified as outstanding national resource waters 

(“ONRWs”) in 38 MRS § 464(4.F.(2)) and are therefore afforded the highest (Tier 3) 

protection under the antidegradation policy. The quality of such waters must be “maintained 

and protected,” which EPA interprets to mean no new or increased discharges to ONRWs or 

their tributaries that would lower water quality, with some exception for limited activities that 

result in temporary and short-term changes in water quality (Water Quality Standards 

Handbook: Second Edition, EPA-823-B-94-005a, August 1994). Stormwater discharges may 

be short-term, but they are not temporary in most cases, and we have not found provisions in 

other state laws that would ensure that any such stormwater discharges are controlled or treated 

such that the Class AA and SA water quality will be maintained and protected. Therefore, 

these provisions are not consistent with Tier 3 antidegradation requirements.

EPA is disapproving 38 M.R.S. § 465(1.C.(1)) and § 465-B(1.C.(1)) as they apply to all Class 

AA and SA waters in Maine, because EPA never acted on these provisions for any waters 

previously. These provisions were submitted to EPA before May 30, 2000 and therefore will 

remain in effect in state waters outside Indian lands until either EPA approves a revision 

promulgated by Maine or EPA promulgates a revision. See 40 C.F.R. § 131.21(c). Maine may 

remedy the disapprovals by removing or narrowing these exceptions to the prohibitions on

direct discharges to ONRWs.

 

58 EPA, Recreational Water Quality Criteria, Office of Water 820-F-12-058, 2012.

59 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, Dissolved Oxygen, May 1, 1986.

60 NSSP, Guide for the Control of Molluscan Shellfish 2013 Revision, 2013.
30

Tidal61 Waters Temperature Criteria [DEP Rule Chapter 582(5)]

EPA’s review of the temperature criteria for tidal waters in DEP Rule Chapter 582(5), is based 

on whether the criteria protect estuarine and marine life uses for waters in Indian lands. 

Chapter 582(5) provides limits on the allowable rise in ambient temperature from individual 

discharges and provides a maximum allowable temperature from cumulative discharges. The 

allowable rise from individual dischargers is 4° F from September 2nd to May 30th and 1.5° F

from June 1st to September 1st, as measured outside of any mixing zone. The maximum 

temperature allowed is 85° F, also as measured outside of any mixing zone.

EPA approved the temperature criteria for tidal waters in state waters in 197362, which were

based, in part, on the U.S. Department of Interior’s (“DOI”) 1968 “Green Book” 

recommendations for temperature differentials in marine waters.63 DOI’s 1968 

recommendations were replaced in 1976 by EPA’s “Red Book” recommendations64 and again, 

most recently, in 1986 by EPA’s Gold Book recommendations. While DEP updated its 

freshwater temperature criteria in 1989 and, among other things, added reference to EPA’s 

recommended criteria to protect indigenous species, DEP has not updated its tidal temperature 

criteria since 1973. They make no reference to EPA’s recommended criteria or to the 

development of equally protective site specific criteria.

The Gold Book recommendations include 1) a maximum acceptable increase in the weekly 

average temperature resulting from artificial sources of 1° C (1.8° F) during all seasons of the 

year, providing the summer maxima are not exceeded; 2) daily temperature cycles 

characteristic of the water body segment should not be altered in either amplitude or frequency; 

and 3) summer thermal maxima, which define the upper thermal limits for the communities of 

the discharge area, should be established on a site-specific basis. Baseline thermal conditions 

should be measured at a site where there is no unnatural thermal addition from any source, 

which is in reasonable proximity to the thermal discharge (within 5 miles) and which has a 

similar hydrography to that of the receiving waters at the discharge. 65 

The Gold Book also explains the importance of maintaining ambient water temperatures close 

to the baseline:

...life associated with the aquatic environment in any location has its species 

composition and activity regulated by water temperature. Since essentially all of these 

organisms are so-called “cold blooded” or poikilotherms, the temperature of the water 

regulates their metabolism and ability to survive and reproduce effectively.66

 

61Although no definition of “tidal waters” is currently included in Maine’s WQS, EPA assumes that the term “tidal 

waters” means “estuarine and marine waters,” as defined in 38 M.R.S. § 361-A(5), since that definition was 

previously used to define “tidal waters.” See L.D.1503, “An Act to Amend the Classification System for Maine 

Waters and Change the Classifications of Certain Waters,” 112th Maine legislature, 1986.

62 December 17, 1973, letter from John A.S. McGlennon, EPA to Kenneth M. Curtis, Governor of Maine.

63 U.S. Department of the Interior, Report of the Committee on Water Quality Criteria (“Green Book”), April 1, 

1968, page 69.

64 EPA, Quality Criteria for Water (“Red Book”), July 1976, page 218.

65 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, May 1, 1986, pages 2-3 of Temperature section.

66 EPA, Quality Criteria for Water 1986, EPA 440/5-86-001, Temperature, May 1, 1986.
31

Maine’s provision that allows a 4° F monthly average temperature rise above maximum 

ambient temperatures is inconsistent with EPA’s recommendation.

Based on NOAA data, the average temperatures in Maine coastal waters in the vicinity of 

Eastport, which is the closest monitoring location to the Passamaquoddy Reservation at 

Pleasant Point, range from 37° F in February to 52° F in September.

67

 

Maine’s designated uses and narrative criteria for estuarine and marine waters in 38 M.R.S. § 

465-B require, for SA waters, that habitat be “natural,” and that estuarine and marine life be as 

naturally occurs; for SB waters, that habitat be characterized as unimpaired, and that the water 

quality be of sufficient quality to support all indigenous species without detrimental changes to 

the biological community; and for SC waters, that the water quality be of sufficient quality to 

support all indigenous species of fish and maintain the structure and function of the resident 

biological community. Maine’s maximum temperature criterion of 85° F in estuarine and 

marine waters could not, by any measure, be considered protective of species which have been 

associated with waters in the 37° F to 52° F range, including indigenous species such as the 

anadromous Atlantic salmon, blueback herring, alewife, and American shad present in the 

vicinity of the St. Croix River. Ambient summertime water temperatures of 85° F are more 

typical of Atlantic coastal waters of the southern United States.68

EPA is disapproving the tidal water temperature criteria for waters in Indian lands because they 

do not protect the designated uses as required by the CWA and by 40 C.F.R. § 131.11(a). 

Maine may remedy EPA’s disapproval by adopting temperature criteria that are consistent with 

EPA’s current recommendations or by providing alternative site specific criteria that are based 

on sound scientific rationale and are sufficient to protect the designated uses. Although the 

disapproval does not apply to tidal waters temperature criteria for Maine waters outside waters 

in Indian lands, EPA recommends that Maine adopt new tidal waters temperature criteria 

statewide, in accordance with the requirements of 40 C.F.R. § 131.6(c) and 40 C.F.R § 

131.20(a).

New or Revised Provisions That are Not WQS and do Not Require an EPA Decision

As noted above, EPA reviewed Maine’s statutes and rules in the State’s docket and EPA’s 

repository and identified provisions that, while important elements of state law, are not WQS 

requiring EPA review and approval or disapproval pursuant to Section 303(c)(2) of the Clean 

Water Act and 40 C.F.R. part 131. As discussed in more detail in EPA’s February 2, 2015 

decision, EPA recently clarified how it determines what is or is not a new or revised WQS, as 

summarized in EPA’s 2012 Frequently Asked Questions (“FAQ”) publication on the subject. 

After careful review of Maine’s statutes and rules in light of this clarification, EPA finds that 

the provisions listed below are not WQS requiring EPA review and approval or disapproval, 

because they do not establish, alter, or in any other way include or address designated uses, 

criteria, or antidegradation requirements. 

 

67NOAA, Water Temperature Table of All Coastal Regions, 

https://www.nodc.noaa.gov/dsdt/cwtg/all_meanT.html

68 Id.
32

 38 M.R.S. §§ 361-A and 466 – Definitions contained in these sections that are not 

specifically listed and approved above;

 38 M.R.S. § 410-H – Nonpoint Source Pollution Program Definitions;

 38 M.R.S. § 410-I – Nonpoint Source Pollution Program Implementation;

 38 M.R.S. § 413(1)-(10) and (11.A, 11.B, 11.C, 11.F, and 11.G) – Waste discharge 

licenses;

 38 M.R.S. § 414-A(1.D), (1.E), (1-A), (1-B), (1-C), and (3)-(6) – Conditions of 

licenses;

 38 M.R.S. § 414-B – Publically Owned Treatment Works;

 38 M.R.S. § 414-C(1), (2), and (4)-(6) – Color Pollution Control;

 38 M.R.S. § 417 – Certain Deposits and Discharges Prohibited;

 38 M.R.S. § 418 -- Log Driving Storage;

 38 M.R.S. § 418-A -- Protection of Lower Penobscot River;

 38 M.R.S. § 419-A – Prohibition on the Use of Tributyltin as an Anti-fouling Agent;

 38 M.R.S. § 420(1), (1-A), (2.I), and (3) – Certain Deposits and Discharges Prohibited; 

 38 M.R.S. § 423 – Discharge of Waste from Watercraft;

 38 M.R.S. § 423-A – Discharge of Waste from Motor Vehicles;

 38 M.R.S. § 451-A – Time Schedule Variances;

 38 M.R.S. § 464(3.A), (3.C), and (3.D) (reports to the Legislature); (4.A.(1), (1.(a), 

1.(b),69 (2), and (6) – (11)) (general discharge provisions); (4.J) (use of assimilative 

capacity); (4.K) (effluent limits for metals); (5) (rulemaking); (6) (implementation of 

biological water quality criteria); (7) (interdepartmental coordination); (8) (development 

of group systems); and (12) (discharges from fish hatcheries);

 38 M.R.S. § 465(2.C.(1) – (5))(exceptions to general requirements on discharges to 

Class A waters); (2.D) (stormwater discharges to Class A waters ); (2.E) (deposit of 

material on banks of Class A waters); (3.C.(2)) (discharges of pesticides for mosquito 

borne diseases to Class B waters); and in (4.B.(2)), the second to last paragraph 

(regarding agreements with licensees and water quality certificate holders.)

 

69 EPA previously concluded in its February 2, 2015 decision that § 464(4)(A.(1)(c)-(f)) are not WQS.
33

 38 M.R.S. § 465-A(1.C) -- Exceptions to prohibitions on discharges to Class GPA 

waters);

 38 M.R.S. § 465-B(2.C, second sentence) – Prohibition on certain new discharges to 

Class SB waters;

 DEP Rule Chapter 450/Chapter 11 -- Administrative Regulations for Hydropower 

Projects;

 DEP Rule Chapter 514 -- Regulations Concerning the Use of Aquatic Pesticides;

 DEP Rule Chapter 519 -- Interim Effluent Limitations and Controls for the Discharge of 

Mercury;

 DEP Rule Chapter 530 – Surface Waters Toxics Control Program, except section 4.B 

(stream design flows), which EPA approved for tribal waters on February 2, 2015;

 DEP Rule Chapter 550 -- Discontinuance of Wastewater Treatment Lagoons;

 DEP Rule Chapter 570 -- Stormwater and Combined Sewer Overflows; and

 DEP Rule Chapter 586 – Rules Pertaining to Discharges to Class A Waters.

EPA has previously approved some of the above-listed provisions for state waters, assuming 

that they were WQS, or without calling out embedded non-WQS language in a longer narrative. 

However, under CWA §303(c), EPA only has the authority and duty to approve or disapprove 

new or revised state WQS. Therefore, EPA’s prior “approvals” related to these provisions have 

no legal effect. EPA is hereby clarifying that in spite of letters that might indicate otherwise, 

the Agency has not taken action pursuant to CWA §303(c) on any of these provisions because 

it had no authority to do so.

70

EPA looks forward to continued cooperation with Maine in the development, review, and 

approval of water quality standards pursuant to our responsibilities under the Clean Water Act. 

As stated in the February 2, 2015 letter, EPA would like to begin discussions with DEP as soon 

 

70 There are several statutes and regulations listed in EPA’s repository that Maine DEP did not include with its 

formal submission to EPA in 2000 of all of its WQS. On the repository, they are accompanied by an asterisk (*) 

indicating that they are not part of the official Maine CWA-WQS docket and not subject to review under the Clean 

Water Act. They include 38 M.R.S. § 419-B (Goals for dates of removal of transformers containing 

polychlorinated biphenyls); 38 M.R.S. § 465-C (Standards of Classification of Groundwater); 38 M.R.S. § 470 

(Classification of Groundwater); 38 M.R.S. § 470-H (In-stream Flow and Water Level Requirements); and DEP 

Rule Chapter 587 (In-stream Flow and Water Level Requirements). EPA agrees that 38 M.R.S. §§ 419-B, 465-C, 

470, and 470-H are not WQS subject to CWA review. EPA would like to better understand Maine’s rationale for 

asserting that Rule Chapter 587 does not contain WQS before concluding that no part of the Rule is subject to 

CWA review.
34

as possible about the criteria that EPA has disapproved. EPA will again attempt to work with 

DEP to schedule such discussions. In the meantime, please contact Ellen Weitzler (at 

weitzler.ellen@epa.gov or 617-918-1582) if you have any questions.

Sincerely,

H. Curtis Spalding

Regional Administrator