1482 Federal Register / Vol. 89, No. 7 / Wednesday, January 10, 2024 / Proposed Rules 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); and 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

Executive Order 12898 (Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations, 59 FR 7629, 

February 16, 1994) directs Federal 

agencies to identify and address 

‘‘disproportionately high and adverse 

human health or environmental effects’’ 

of their actions on minority populations 

and low-income populations to the 

greatest extent practicable and 

permitted by law. EPA defines 

environmental justice (EJ) as ‘‘the fair 

treatment and meaningful involvement 

of all people regardless of race, color, 

national origin, or income with respect 

to the development, implementation, 

and enforcement of environmental laws, 

regulations, and policies.’’ EPA further 

defines the term fair treatment to mean 

that ‘‘no group of people should bear a 

disproportionate burden of 

environmental harms and risks, 

including those resulting from the 

negative environmental consequences of 

industrial, governmental, and 

commercial operations or programs and 

policies.’’ 

The DOEE did not evaluate 

environmental justice considerations as 

part of its SIP submittal; the CAA and 

applicable implementing regulations 

neither prohibit nor require such an 

evaluation. EPA did not perform an EJ 

analysis and did not consider EJ in this 

proposed rulemaking. Due to the nature 

of the proposed action being taken here, 

this proposed rulemaking is expected to 

have a neutral to positive impact on the 

air quality of the affected area. 

Consideration of EJ is not required as 

part of this action, and there is no 

information in the record inconsistent 

with the stated goal of E.O. 12898 of 

achieving environmental justice for 

people of color, low-income 

populations, and Indigenous peoples. 

In addition, this proposed 

rulemaking, to remove the District’s 

Stage II vapor recovery requirements 

from the SIP does not have tribal 

implications as specified by Executive 

Order 13175 (65 FR 67249, November 9, 

2000), because the SIP is not approved 

to apply in Indian country located in the 

District, and EPA notes that it will not 

impose substantial direct costs on tribal 

governments or preempt tribal law. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Ozone, Reporting and recordkeeping 

requirements, Volatile organic 

compounds. 

Diana Esher, 

Acting Regional Administrator, Region III. 

[FR Doc. 2024–00161 Filed 1–9–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

EPA–R01–OAR–2023–0185; FRL– 

11616–01–R1] 

Approval and Promulgation of Air 

Quality Implementation Plans; 

Massachusetts; Regional Haze State 

Implementation Plan for the Second 

Implementation Period 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to approve 

the Regional Haze State Implementation 

Plan (SIP) revision submitted by 

Massachusetts on July 22, 2021, as 

satisfying applicable requirements 

under the Clean Air Act (CAA) and 

EPA’s Regional Haze Rule for the 

program’s second implementation 

period. Massachusetts’ SIP submission 

addresses the requirement that states 

must periodically revise their long-term 

strategies for making reasonable 

progress towards the national goal of 

preventing any future, and remedying 

any existing, anthropogenic impairment 

of visibility, including regional haze, in 

mandatory Class I Federal areas. The 

SIP submission also addresses other 

applicable requirements for the second 

implementation period of the regional 

haze program. The EPA is taking this 

action pursuant to sections 110 and 

169A of the Clean Air Act. 

DATES: Written comments must be 

received on or before February 9, 2024. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R01– 

OAR–2023–0185 at https://

www.regulations.gov. For comments 

submitted at Regulations.gov, follow the 

online instructions for submitting 

comments. Once submitted, comments 

cannot be edited or removed from 

Regulations.gov. For either manner of 

submission, the EPA may publish any 

comment received to its public docket. 

Do not submit electronically any 

information you consider to be 

confidential business information (CBI) 

or other information whose disclosure is 

restricted by statute. Multimedia 

submissions (audio, video, etc.) must be 

accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

submission (i.e., on the web, cloud, or 

other file sharing system). For 

additional submission methods, please 

contact the person identified in the FOR

FURTHER INFORMATION CONTACT section. 

For the full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

FOR FURTHER INFORMATION CONTACT: 

David Mackintosh, U.S. Environmental 

Protection Agency, Region 1, Air 

Quality Branch, 5 Post Office Square— 

Suite 100, (Mail code 5–MO), Boston, 

MA 02109–3912, at 617–918–1584, or 

by email at Mackintosh.David@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. What action is the EPA proposing? 

II. Background and Requirements for 

Regional Haze Plans 

A. Regional Haze Background 

B. Roles of Agencies in Addressing 

Regional Haze 

III. Requirements for Regional Haze Plans for 

the Second Implementation Period 

A. Identification of Class I Areas 

B. Calculations of Baseline, Current, and 

Natural Visibility Conditions; Progress to 

Date; and the Uniform Rate of Progress 

C. Long-Term Strategy for Regional Haze 

D. Reasonable Progress Goals 

E. Monitoring Strategy and Other State 

Implementation Plan Requirements 

F. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

G. Requirements for State and Federal 

Land Manager Coordination 

IV. The EPA’s Evaluation of Massachusetts’ 

Regional Haze Submission for the 

Second Implementation Period 

A. Background on Massachusetts’ First 

Implementation Period SIP Submission 

B. Massachusetts’ Second Implementation 

Period SIP Submission and the EPA’s 

Evaluation 

C. Identification of Class I Areas 

D. Calculations of Baseline, Current, and 

Natural Visibility Conditions; Progress to 

Date; and the Uniform Rate of Progress 

E. Long-Term Strategy for Regional Haze 

a. Massachusetts’ Response to the Six 

MANE–VU Asks 


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1Areas statutorily designated as mandatory Class 

I Federal areas consist of national parks exceeding 

6,000 acres, wilderness areas and national memorial 

parks exceeding 5,000 acres, and all international 

parks that were in existence on August 7, 1977. 

CAA 162(a). There are 156 mandatory Class I areas. 

The list of areas to which the requirements of the 

visibility protection program apply is in 40 CFR 

part 81, subpart D. 

2 In addition to the generally applicable regional 

haze provisions at 40 CFR 51.308, the EPA also 

promulgated regulations specific to addressing 

regional haze visibility impairment in Class I areas 

on the Colorado Plateau at 40 CFR 51.309. The 

latter regulations are applicable only for specific 

jurisdictions’ regional haze plans submitted no later 

than December 17, 2007, and thus are not relevant 

here. 

3There are several ways to measure the amount 

of visibility impairment, i.e., haze. One such 

measurement is the deciview, which is the 

principal metric used by the RHR. Under many 

circumstances, a change in one deciview will be 

perceived by the human eye to be the same on both 

clear and hazy days. The deciview is unitless. It is 

proportional to the logarithm of the atmospheric 

extinction of light, which is the perceived dimming 

of light due to its being scattered and absorbed as 

it passes through the atmosphere. Atmospheric light 

extinction (bext) is a metric used to for expressing 

visibility and is measured in inverse megameters 

(Mm-1). The EPA’s Guidance on Regional Haze 

State Implementation Plans for the Second 

Implementation Period (‘‘2019 Guidance’’) offers 

the flexibility for the use of light extinction in 

certain cases. Light extinction can be simpler to use 

in calculations than deciviews, since it is not a 

logarithmic function. See, e.g., 2019 Guidance at 16, 

19, https://www.epa.gov/visibility/guidanceregional-haze-state-implementation-plans-secondimplementation-period, The EPA Office of Air 

Quality Planning and Standards, Research Triangle 

Park (August 20, 2019). The formula for the 

deciview is 10 ln (bext)/10 Mm¥1). 40 CFR 51.301. 

4The RHR expresses the statutory requirement for 

states to submit plans addressing out-of-state class 

I areas by providing that states must address 

visibility impairment ‘‘in each mandatory Class I 

Federal area located outside the State that may be 

affected by emissions from within the State.’’ 40 

CFR 51.308(d), (f). 

5 In addition to each of the fifty states, the EPA 

also concluded that the Virgin Islands and District 

of Columbia must also submit regional haze SIPs 

because they either contain a Class I area or contain 

sources whose emissions are reasonably anticipated 

to contribute regional haze in a Class I area. See 40 

CFR 51.300(b), (d)(3). 

b. The EPA’s Evaluation of Massachusetts’ 

Response to the Six MANE–VU Asks and 

Compliance With § 51.308(f)(2)(i) 

c. Additional Long-Term Strategy 

Requirements 

F. Reasonable Progress Goals 

G. Monitoring Strategy and Other 

Implementation Plan Requirements 

H. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

I. Requirements for State and Federal Land 

Manager Coordination 

V. Proposed Action 

VI. Incorporation by Reference 

VII. Statutory and Executive Order Reviews 

I. What action is the EPA proposing? 

On July 22, 2021, supplemented on 

June 15, 2022, the Massachusetts 

Department of Environmental Protection 

(MassDEP) submitted a revision to its 

SIP to address regional haze for the 

second implementation period. 

MassDEP made this SIP submission to 

satisfy the requirements of the CAA’s 

regional haze program pursuant to CAA 

sections 169A and 169B and 40 CFR 

51.308. The EPA is proposing to find 

that the Massachusetts regional haze SIP 

submission for the second 

implementation period meets the 

applicable statutory and regulatory 

requirements and thus proposes to 

approve Massachusetts’ submission into 

its SIP. 

II. Background and Requirements for 

Regional Haze Plans 

A. Regional Haze Background 

In the 1977 CAA Amendments, 

Congress created a program for 

protecting visibility in the nation’s 

mandatory Class I Federal areas, which 

include certain national parks and 

wilderness areas.1 CAA 169A. The CAA 

establishes as a national goal the 

‘‘prevention of any future, and the 

remedying of any existing, impairment 

of visibility in mandatory class I Federal 

areas which impairment results from 

manmade air pollution.’’ CAA 

169A(a)(1). The CAA further directs the 

EPA to promulgate regulations to assure 

reasonable progress toward meeting this 

national goal. CAA 169A(a)(4). On 

December 2, 1980, the EPA promulgated 

regulations to address visibility 

impairment in mandatory Class I 

Federal areas (hereinafter referred to as 

‘‘Class I areas’’) that is ‘‘reasonably 

attributable’’ to a single source or small 

group of sources. (45 FR 80084, 

December 2, 1980). These regulations, 

codified at 40 CFR 51.300 through 

51.307, represented the first phase of the 

EPA’s efforts to address visibility 

impairment. In 1990, Congress added 

section 169B to the CAA to further 

address visibility impairment, 

specifically, impairment from regional 

haze. CAA 169B. The EPA promulgated 

the Regional Haze Rule (RHR), codified 

at 40 CFR 51.308,2 on July 1, 1999. (64 

FR 35714, July 1, 1999). These regional 

haze regulations are a central 

component of the EPA’s comprehensive 

visibility protection program for Class I 

areas. 

Regional haze is visibility impairment 

that is produced by a multitude of 

anthropogenic sources and activities 

which are located across a broad 

geographic area and that emit pollutants 

that impair visibility. Visibility 

impairing pollutants include fine and 

coarse particulate matter (PM) (e.g., 

sulfates, nitrates, organic carbon, 

elemental carbon, and soil dust) and 

their precursors (e.g., sulfur dioxide 

(SO2), nitrogen oxides (NOX), and, in 

some cases, volatile organic compounds 

(VOC) and ammonia (NH3)). Fine 

particle precursors react in the 

atmosphere to form fine particulate 

matter (PM2.5), which impairs visibility 

by scattering and absorbing light. 

Visibility impairment reduces the 

perception of clarity and color, as well 

as visible distance.3

To address regional haze visibility 

impairment, the 1999 RHR established 

an iterative planning process that 

requires both states in which Class I 

areas are located and states ‘‘the 

emissions from which may reasonably 

be anticipated to cause or contribute to 

any impairment of visibility’’ in a Class 

I area to periodically submit SIP 

revisions to address such impairment. 

CAA 169A(b)(2); 4 see also 40 CFR 

51.308(b), (f) (establishing submission 

dates for iterative regional haze SIP 

revisions); (64 FR at 35768, July 1, 

1999). Under the CAA, each SIP 

submission must contain ‘‘a long-term 

(ten to fifteen years) strategy for making 

reasonable progress toward meeting the 

national goal,’’ CAA 169A(b)(2)(B); the 

initial round of SIP submissions also 

had to address the statutory requirement 

that certain older, larger sources of 

visibility impairing pollutants install 

and operate the best available retrofit 

technology (BART). CAA 169A(b)(2)(A); 

40 CFR 51.308(d), (e). States’ first 

regional haze SIPs were due by 

December 17, 2007, 40 CFR 51.308(b), 

with subsequent SIP submissions 

containing updated long-term strategies 

originally due July 31, 2018, and every 

ten years thereafter. (64 FR at 35768, 

July 1, 1999). The EPA established in 

the 1999 RHR that all states either have 

Class I areas within their borders or 

‘‘contain sources whose emissions are 

reasonably anticipated to contribute to 

regional haze in a Class I area’’; 

therefore, all states must submit regional 

haze SIPs.5 Id. at 35721. 

Much of the focus in the first 

implementation period of the regional 

haze program, which ran from 2007 

through 2018, was on satisfying states’ 

BART obligations. First implementation 

period SIPs were additionally required 

to contain long-term strategies for 

making reasonable progress toward the 

national visibility goal, of which BART 

is one component. The core required 

elements for the first implementation 

period SIPs (other than BART) are laid 

out in 40 CFR 51.308(d). Those 

provisions required that states 

containing Class I areas establish 

reasonable progress goals (RPGs) that 

are measured in deciviews and reflect 

the anticipated visibility conditions at 


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6EPA established the URP framework in the 1999 

RHR to provide ‘‘an equitable analytical approach’’ 

to assessing the rate of visibility improvement at 

Class I areas across the country. The start point for 

the URP analysis is 2004 and the endpoint was 

calculated based on the amount of visibility 

improvement that was anticipated to result from 

implementation of existing CAA programs over the 

period from the mid-1990s to approximately 2005. 

Assuming this rate of progress would continue into 

the future, EPA determined that natural visibility 

conditions would be reached in 60 years, or 2064 

(60 years from the baseline starting point of 2004). 

However, EPA did not establish 2064 as the year 

by which the national goal must be reached. 64 FR 

at 35731–32. That is, the URP and the 2064 date are 

not enforceable targets, but are rather tools that 

‘‘allow for analytical comparisons between the rate 

of progress that would be achieved by the state’s 

chosen set of control measures and the URP.’’ (82 

FR 3078, 3084, January 10, 2017). 

7The EPA’s regulations define ‘‘Federal Land 

Manager’’ as ‘‘the Secretary of the department with 

authority over the Federal Class I area (or the 

Secretary’s designee) or, with respect to RooseveltCampobello International Park, the Chairman of the 

Roosevelt-Campobello International Park 

Commission.’’ 40 CFR 51.301. 

8 Guidance on Regional Haze State 

Implementation Plans for the Second 

Implementation Period. https://www.epa.gov/ 

visibility/guidance-regional-haze-stateimplementation-plans-second-implementationperiod. The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (August 20, 

2019). 

9Clarifications Regarding Regional Haze State 

Implementation Plans for the Second 

Implementation Period. https://www.epa.gov/ 

system/files/documents/2021-07/clarificationsregarding-regional-haze-state-implementationplans-for-the-second-implementation-period.pdf. 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (July 8, 2021). 

10Technical Guidance on Tracking Visibility 

Progress for the Second Implementation Period of 

the Regional Haze Program. https://www.epa.gov/ 

visibility/technical-guidance-tracking-visibilityprogress-second-implementation-period-regional. 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park. (December 20, 

2018). 

11Recommendation for the Use of Patched and 

Substituted Data and Clarification of Data 

Completeness for Tracking Visibility Progress for 

the Second Implementation Period of the Regional 

Haze Program. https://www.epa.gov/visibility/ 

memo-and-technical-addendum-ambient-datausage-and-completeness-regional-haze-program. 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (June 3, 2020). 

the end of the implementation period 

including from implementation of 

states’ long-term strategies. The first 

planning period RPGs were required to 

provide for an improvement in visibility 

for the most impaired days over the 

period of the implementation plan and 

ensure no degradation in visibility for 

the least impaired days over the same 

period. In establishing the RPGs for any 

Class I area in a state, the state was 

required to consider four statutory 

factors: the costs of compliance, the 

time necessary for compliance, the 

energy and non-air quality 

environmental impacts of compliance, 

and the remaining useful life of any 

potentially affected sources. CAA 

169A(g)(1); 40 CFR 51.308(d)(1). 

States were also required to calculate 

baseline (using the five-year period of 

2000–2004) and natural visibility 

conditions (i.e., visibility conditions 

without anthropogenic visibility 

impairment) for each Class I area, and 

to calculate the linear rate of progress 

needed to attain natural visibility 

conditions, assuming a starting point of 

baseline visibility conditions in 2004 

and ending with natural conditions in 

2064. This linear interpolation is known 

as the uniform rate of progress (URP) 

and is used as a tracking metric to help 

states assess the amount of progress they 

are making towards the national 

visibility goal over time in each Class I 

area.6 40 CFR 51.308(d)(1)(i)(B), (d)(2). 

The 1999 RHR also provided that States’ 

long-term strategies must include the 

‘‘enforceable emissions limitations, 

compliance, schedules, and other 

measures as necessary to achieve the 

reasonable progress goals.’’ 40 CFR 

51.308(d)(3). In establishing their longterm strategies, states are required to 

consult with other states that also 

contribute to visibility impairment in a 

given Class I area and include all 

measures necessary to obtain their 

shares of the emission reductions 

needed to meet the RPGs. 40 CFR 

51.308(d)(3)(i), (ii). Section 51.308(d) 

also contains seven additional factors 

states must consider in formulating their 

long-term strategies, 40 CFR 

51.308(d)(3)(v), as well as provisions 

governing monitoring and other 

implementation plan requirements. 40 

CFR 51.308(d)(4). Finally, the 1999 RHR 

required states to submit periodic 

progress reports—SIP revisions due 

every five years that contain information 

on states’ implementation of their 

regional haze plans and an assessment 

of whether anything additional is 

needed to make reasonable progress, see 

40 CFR 51.308(g), (h)—and to consult 

with the Federal Land Manager(s) 7

(FLMs) responsible for each Class I area 

according to the requirements in CAA 

169A(d) and 40 CFR 51.308(i). 

On January 10, 2017, the EPA 

promulgated revisions to the RHR, (82 

FR 3078, January 10, 2017), that apply 

for the second and subsequent 

implementation periods. The 2017 

rulemaking made several changes to the 

requirements for regional haze SIPs to 

clarify States’ obligations and streamline 

certain regional haze requirements. The 

revisions to the regional haze program 

for the second and subsequent 

implementation periods focused on the 

requirement that States’ SIPs contain 

long-term strategies for making 

reasonable progress towards the 

national visibility goal. The reasonable 

progress requirements as revised in the 

2017 rulemaking (referred to here as the 

2017 RHR Revisions) are codified at 40 

CFR 51.308(f). Among other changes, 

the 2017 RHR Revisions adjusted the 

deadline for States to submit their 

second implementation period SIPs 

from July 31, 2018, to July 31, 2021, 

clarified the order of analysis and the 

relationship between RPGs and the 

long-term strategy, and focused on 

making visibility improvements on the 

days with the most anthropogenic 

visibility impairment, as opposed to the 

days with the most visibility 

impairment overall. The EPA also 

revised requirements of the visibility 

protection program related to periodic 

progress reports and FLM consultation. 

The specific requirements applicable to 

second implementation period regional 

haze SIP submissions are addressed in 

detail below. 

The EPA provided guidance to the 

states for their second implementation 

period SIP submissions in the preamble 

to the 2017 RHR Revisions as well as in 

subsequent, stand-alone guidance 

documents. In August 2019, the EPA 

issued ‘‘Guidance on Regional Haze 

State Implementation Plans for the 

Second Implementation Period’’ (‘‘2019 

Guidance’’).8 On July 8, 2021, the EPA 

issued a memorandum containing 

‘‘Clarifications Regarding Regional Haze 

State Implementation Plans for the 

Second Implementation Period’’ (‘‘2021 

Clarifications Memo’’).9 Additionally, 

the EPA further clarified the 

recommended procedures for processing 

ambient visibility data and optionally 

adjusting the URP to account for 

international anthropogenic and 

prescribed fire impacts in two technical 

guidance documents: the December 

2018 ‘‘Technical Guidance on Tracking 

Visibility Progress for the Second 

Implementation Period of the Regional 

Haze Program’’ (‘‘2018 Visibility 

Tracking Guidance’’),10 and the June 

2020 ‘‘Recommendation for the Use of 

Patched and Substituted Data and 

Clarification of Data Completeness for 

Tracking Visibility Progress for the 

Second Implementation Period of the 

Regional Haze Program’’ and associated 

Technical Addendum (‘‘2020 Data 

Completeness Memo’’).11

As previously explained in the 2021 

Clarifications Memo, EPA intends the 

second implementation period of the 

regional haze program to secure 

meaningful reductions in visibility 

impairing pollutants that build on the 

significant progress states have achieved 

to date. The Agency also recognizes that 

analyses regarding reasonable progress 


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12See, e.g., H.R. Rep No. 95–294 at 205 (‘‘In 

determining how to best remedy the growing 

visibility problem in these areas of great scenic 

importance, the committee realizes that as a matter 

of equity, the national ambient air quality standards 

cannot be revised to adequately protect visibility in 

all areas of the country.’’), (‘‘the mandatory class I 

increments of [the PSD program] do not adequately 

protect visibility in class I areas’’). 

13RPOs are sometimes also referred to as ‘‘multijurisdictional organizations,’’ or MJOs. For the 

purposes of this notice, the terms RPO and MJO are 

synonymous. 

14EPA explained in the 2017 RHR Revisions that 

we were adopting new regulatory language in 40 

CFR 51.308(f) that, unlike the structure in 

51.308(d), ‘‘tracked the actual planning sequence.’’ 

(82 FR 3091, January 10, 2017). 

15The five ‘‘additional factors’’ for consideration 

in section 51.308(f)(2)(iv) are distinct from the four 

factors listed in CAA section 169A(g)(1) and 40 CFR 

51.308(f)(2)(i) that states must consider and apply 

to sources in determining reasonable progress. 

are state-specific and that, based on 

states’ and sources’ individual 

circumstances, what constitutes 

reasonable reductions in visibility 

impairing pollutants will vary from 

state-to-state. While there exist many 

opportunities for states to leverage both 

ongoing and upcoming emission 

reductions under other CAA programs, 

the Agency expects states to undertake 

rigorous reasonable progress analyses 

that identify further opportunities to 

advance the national visibility goal 

consistent with the statutory and 

regulatory requirements. See generally 

2021 Clarifications Memo. This is 

consistent with Congress’s 

determination that a visibility 

protection program is needed in 

addition to the CAA’s National Ambient 

Air Quality Standards and Prevention of 

Significant Deterioration programs, as 

further emission reductions may be 

necessary to adequately protect 

visibility in Class I areas throughout the 

country.12

B. Roles of Agencies in Addressing 

Regional Haze 

Because the air pollutants and 

pollution affecting visibility in Class I 

areas can be transported over long 

distances, successful implementation of 

the regional haze program requires longterm, regional coordination among 

multiple jurisdictions and agencies that 

have responsibility for Class I areas and 

the emissions that impact visibility in 

those areas. In order to address regional 

haze, states need to develop strategies in 

coordination with one another, 

considering the effect of emissions from 

one jurisdiction on the air quality in 

another. Five regional planning 

organizations (RPOs),13 which include 

representation from state and tribal 

governments, the EPA, and FLMs, were 

developed in the lead-up to the first 

implementation period to address 

regional haze. RPOs evaluate technical 

information to better understand how 

emissions from State and Tribal land 

impact Class I areas across the country, 

pursue the development of regional 

strategies to reduce emissions of 

particulate matter and other pollutants 

leading to regional haze, and help states 

meet the consultation requirements of 

the RHR. 

The Mid-Atlantic/Northeast Visibility 

Union (MANE–VU), one of the five 

RPOs described above, is a collaborative 

effort of state governments, tribal 

governments, and various Federal 

agencies established to initiate and 

coordinate activities associated with the 

management of regional haze, visibility, 

and other air quality issues in the MidAtlantic and Northeast corridor of the 

United States. Member states and tribal 

governments (listed alphabetically) 

include Connecticut, Delaware, the 

District of Columbia, Maine, Maryland, 

Massachusetts, New Hampshire, New 

Jersey, New York, Pennsylvania, 

Penobscot Indian Nation, Rhode Island, 

St. Regis Mohawk Tribe, and Vermont. 

The Federal partner members of MANE– 

VU are EPA, U.S. National Parks Service 

(NPS), U.S. Fish and Wildlife Service 

(FWS), and U.S. Forest Service (USFS). 

III. Requirements for Regional Haze 

Plans for the Second Implementation 

Period 

Under the CAA and EPA’s 

regulations, all 50 states, the District of 

Columbia, and the U.S. Virgin Islands 

are required to submit regional haze 

SIPs satisfying the applicable 

requirements for the second 

implementation period of the regional 

haze program by July 31, 2021. Each 

state’s SIP must contain a long-term 

strategy for making reasonable progress 

toward meeting the national goal of 

remedying any existing and preventing 

any future anthropogenic visibility 

impairment in Class I areas. CAA 

169A(b)(2)(B). To this end, § 51.308(f) 

lays out the process by which states 

determine what constitutes their longterm strategies, with the order of the 

requirements in § 51.308(f)(1) through 

(f)(3) generally mirroring the order of 

the steps in the reasonable progress 

analysis 14 and (f)(4) through (f)(6) 

containing additional, related 

requirements. Broadly speaking, a state 

first must identify the Class I areas 

within the state and determine the Class 

I areas outside the state in which 

visibility may be affected by emissions 

from the state. These are the Class I 

areas that must be addressed in the 

state’s long-term strategy. See 40 CFR 

51.308(f), (f)(2). For each Class I area 

within its borders, a state must then 

calculate the baseline, current, and 

natural visibility conditions for that 

area, as well as the visibility 

improvement made to date and the URP. 

See 40 CFR 51.308(f)(1). Each state 

having a Class I area and/or emissions 

that may affect visibility in a Class I area 

must then develop a long-term strategy 

that includes the enforceable emission 

limitations, compliance schedules, and 

other measures that are necessary to 

make reasonable progress in such areas. 

A reasonable progress determination is 

based on applying the four factors in 

CAA section 169A(g)(1) to sources of 

visibility-impairing pollutants that the 

state has selected to assess for controls 

for the second implementation period. 

See 40 CFR 51.308(f)(2). Additionally, 

as further explained below, the RHR at 

40 CFR 51.308(f)(2)(iv) separately 

provides five ‘‘additional factors’’ 15 that 

states must consider in developing their 

long-term strategies. A state evaluates 

potential emission reduction measures 

for those selected sources and 

determines which are necessary to make 

reasonable progress. Those measures are 

then incorporated into the state’s longterm strategy. After a state has 

developed its long-term strategy, it then 

establishes RPGs for each Class I area 

within its borders by modeling the 

visibility impacts of all reasonable 

progress controls at the end of the 

second implementation period, i.e., in 

2028, as well as the impacts of other 

requirements of the CAA. The RPGs 

include reasonable progress controls not 

only for sources in the state in which 

the Class I area is located, but also for 

sources in other states that contribute to 

visibility impairment in that area. The 

RPGs are then compared to the baseline 

visibility conditions and the URP to 

ensure that progress is being made 

towards the statutory goal of preventing 

any future and remedying any existing 

anthropogenic visibility impairment in 

Class I areas. 40 CFR 51.308(f)(2)–(3). 

In addition to satisfying the 

requirements at 40 CFR 51.308(f) related 

to reasonable progress, the regional haze 

SIP revisions for the second 

implementation period must address the 

requirements in § 51.308(g)(1) through 

(5) pertaining to periodic reports 

describing progress towards the RPGs, 

40 CFR 51.308(f)(5), as well as 

requirements for FLM consultation that 

apply to all visibility protection SIPs 

and SIP revisions. 40 CFR 51.308(i). 

A state must submit its regional haze 

SIP and subsequent SIP revisions to the 

EPA according to the requirements 

applicable to all SIP revisions under the 

CAA and EPA’s regulations. See CAA 


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16The 2018 Visibility Tracking Guidance 

references and relies on parts of the 2003 Tracking 

Guidance: ‘‘Guidance for Tracking Progress Under 

the Regional Haze Rule,’’ which can be found at 

https://www3.epa.gov/ttnamti1/files/ambient/ 

visible/tracking.pdf. 

17This notice also refers to the 20% clearest and 

20% most anthropogenically impaired days as the 

‘‘clearest’’ and ‘‘most impaired’’ or ‘‘most 

anthropogenically impaired’’ days, respectively. 

18The RHR at 40 CFR 51.308(f)(1)(ii) contains an 

error related to the requirement for calculating two 

sets of natural conditions values. The rule says 

‘‘most impaired days or the clearest days’’ where it 

should say ‘‘most impaired days and clearest days.’’ 

This is an error that was intended to be corrected 

in the 2017 RHR Revisions but did not get corrected 

in the final rule language. This is supported by the 

preamble text at 82 FR 3098: ‘‘In the final version 

of 40 CFR 51.308(f)(1)(ii), an occurrence of ‘‘or’’ has 

been corrected to ‘‘and’’ to indicate that natural 

visibility conditions for both the most impaired 

days and the clearest days must be based on 

available monitoring information.’’ 

19Being on or below the URP is not a ‘‘safe 

harbor’’; i.e., achieving the URP does not mean that 

a Class I area is making ‘‘reasonable progress’’ and 

does not relieve a state from using the four statutory 

factors to determine what level of control is needed 

to achieve such progress. See, e.g., 82 FR at 3093. 

169(b)(2); CAA 110(a). Upon EPA 

approval, a SIP is enforceable by the 

Agency and the public under the CAA. 

If EPA finds that a state fails to make a 

required SIP revision, or if the EPA 

finds that a state’s SIP is incomplete or 

if disapproves the SIP, the Agency must 

promulgate a federal implementation 

plan (FIP) that satisfies the applicable 

requirements. CAA 110(c)(1). 

A. Identification of Class I Areas 

The first step in developing a regional 

haze SIP is for a state to determine 

which Class I areas, in addition to those 

within its borders, ‘‘may be affected’’ by 

emissions from within the state. In the 

1999 RHR, the EPA determined that all 

states contribute to visibility 

impairment in at least one Class I area, 

64 FR at 35720–22, and explained that 

the statute and regulations lay out an 

‘‘extremely low triggering threshold’’ for 

determining ‘‘whether States should be 

required to engage in air quality 

planning and analysis as a prerequisite 

to determining the need for control of 

emissions from sources within their 

State.’’ Id. at 35721. 

A state must determine which Class I 

areas must be addressed by its SIP by 

evaluating the total emissions of 

visibility impairing pollutants from all 

sources within the state. While the RHR 

does not require this evaluation to be 

conducted in any particular manner, 

EPA’s 2019 Guidance provides 

recommendations for how such an 

assessment might be accomplished, 

including by, where appropriate, using 

the determinations previously made for 

the first implementation period. 2019 

Guidance at 8–9. In addition, the 

determination of which Class I areas 

may be affected by a state’s emissions is 

subject to the requirement in 40 CFR 

51.308(f)(2)(iii) to ‘‘document the 

technical basis, including modeling, 

monitoring, cost, engineering, and 

emissions information, on which the 

State is relying to determine the 

emission reduction measures that are 

necessary to make reasonable progress 

in each mandatory Class I Federal area 

it affects.’’ 

B. Calculations of Baseline, Current, 

and Natural Visibility Conditions; 

Progress to Date; and the Uniform Rate 

of Progress 

As part of assessing whether a SIP 

submission for the second 

implementation period is providing for 

reasonable progress towards the 

national visibility goal, the RHR 

contains requirements in § 51.308(f)(1) 

related to tracking visibility 

improvement over time. The 

requirements of this subsection apply 

only to states having Class I areas within 

their borders; the required calculations 

must be made for each such Class I area. 

EPA’s 2018 Visibility Tracking 

Guidance 16 provides recommendations 

to assist states in satisfying their 

obligations under § 51.308(f)(1)— 

specifically, in developing information 

on baseline, current, and natural 

visibility conditions, and in making 

optional adjustments to the URP to 

account for the impacts of international 

anthropogenic emissions and prescribed 

fires. See 82 FR at 3103–05. 

The RHR requires tracking of 

visibility conditions on two sets of days: 

the clearest and the most impaired days. 

Visibility conditions for both sets of 

days are expressed as the average 

deciview index for the relevant five-year 

period (the period representing baseline 

or current visibility conditions). The 

RHR provides that the relevant sets of 

days for visibility tracking purposes are 

the 20% clearest (the 20% of monitored 

days in a calendar year with the lowest 

values of the deciview index) and 20% 

most impaired days (the 20% of 

monitored days in a calendar year with 

the highest amounts of anthropogenic 

visibility impairment).17 40 CFR 51.301. 

A state must calculate visibility 

conditions for both the 20% clearest and 

20% most impaired days for the 

baseline period of 2000–2004 and the 

most recent five-year period for which 

visibility monitoring data are available 

(representing current visibility 

conditions). 40 CFR 51.308(f)(1)(i), (iii). 

States must also calculate natural 

visibility conditions for the clearest and 

most impaired days,18 by estimating the 

conditions that would exist on those 

two sets of days absent anthropogenic 

visibility impairment. 40 CFR 

51.308(f)(1)(ii). Using all these data, 

states must then calculate, for each 

Class I area, the amount of progress 

made since the baseline period (2000– 

2004) and how much improvement is 

left to achieve in order to reach natural 

visibility conditions. 

Using the data for the set of most 

impaired days only, states must plot a 

line between visibility conditions in the 

baseline period and natural visibility 

conditions for each Class I area to 

determine the URP—the amount of 

visibility improvement per year, 

measured in deciviews, that would need 

to be achieved during each 

implementation period in order to 

achieve natural visibility conditions by 

the end of 2064. The URP is used in 

later steps of the reasonable progress 

analysis for informational purposes and 

to provide a non-enforceable benchmark 

against which to assess a Class I area’s 

rate of visibility improvement.19

Additionally, in the 2017 RHR 

Revisions, the EPA provided states the 

option of proposing to adjust the 

endpoint of the URP to account for 

impacts of anthropogenic sources 

outside the United States and/or 

impacts of certain types of wildland 

prescribed fires. These adjustments, 

which must be approved by the EPA, 

are intended to avoid any perception 

that states should compensate for 

impacts from international 

anthropogenic sources and to give states 

the flexibility to determine that limiting 

the use of wildland-prescribed fire is 

not necessary for reasonable progress. 

82 FR 3107 footnote 116. 

EPA’s 2018 Visibility Tracking 

Guidance can be used to help satisfy the 

40 CFR 51.308(f)(1) requirements, 

including in developing information on 

baseline, current, and natural visibility 

conditions, and in making optional 

adjustments to the URP. In addition, the 

2020 Data Completeness Memo provides 

recommendations on the data 

completeness language referenced in 

§ 51.308(f)(1)(i) and provides updated 

natural conditions estimates for each 

Class I area. 

C. Long-Term Strategy for Regional 

Haze 

The core component of a regional 

haze SIP submission is a long-term 

strategy that addresses regional haze in 

each Class I area within a state’s borders 

and each Class I area that may be 

affected by emissions from the state. 

The long-term strategy ‘‘must include 

the enforceable emissions limitations, 

compliance schedules, and other 


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20Similarly, in responding to comments on the 

2017 RHR Revisions EPA explained that ‘‘[a] state 

should not fail to address its many relatively lowimpact sources merely because it only has such 

sources and another state has even more low-impact 

sources and/or some high impact sources.’’ 

Responses to Comments on Protection of Visibility: 

Amendments to Requirements for State Plans; 

Proposed Rule (81 FR 26942, May 4, 2016) at 87– 

88. 

21The CAA provides that, ‘‘[i]n determining 

reasonable progress there shall be taken into 

consideration’’ the four statutory factors. CAA 

169A(g)(1). However, in addition to four-factor 

analyses for selected sources, groups of sources, or 

source categories, a state may also consider 

additional emission reduction measures for 

inclusion in its long-term strategy, e.g., from other 

newly adopted, on-the-books, or on-the-way rules 

and measures for sources not selected for four-factor 

analysis for the second planning period. 

22 ‘‘Each source’’ or ‘‘particular source’’ is used 

here as shorthand. While a source-specific analysis 

is one way of applying the four factors, neither the 

statute nor the RHR requires states to evaluate 

individual sources. Rather, states have ‘‘the 

flexibility to conduct four-factor analyses for 

specific sources, groups of sources or even entire 

source categories, depending on state policy 

preferences and the specific circumstances of each 

state.’’ 82 FR at 3088. However, not all approaches 

to grouping sources for four-factor analysis are 

necessarily reasonable; the reasonableness of 

grouping sources in any particular instance will 

depend on the circumstances and the manner in 

which grouping is conducted. If it is feasible to 

establish and enforce different requirements for 

sources or subgroups of sources, and if relevant 

factors can be quantified for those sources or 

subgroups, then states should make a separate 

reasonable progress determination for each source 

or subgroup. 2021 Clarifications Memo at 7–8. 

measures that are necessary to make 

reasonable progress, as determined 

pursuant to (f)(2)(i) through (iv).’’ 40 

CFR 51.308(f)(2). The amount of 

progress that is ‘‘reasonable progress’’ is 

based on applying the four statutory 

factors in CAA section 169A(g)(1) in an 

evaluation of potential control options 

for sources of visibility impairing 

pollutants, which is referred to as a 

‘‘four-factor’’ analysis. The outcome of 

that analysis is the emission reduction 

measures that a particular source or 

group of sources needs to implement in 

order to make reasonable progress 

towards the national visibility goal. See 

40 CFR 51.308(f)(2)(i). Emission 

reduction measures that are necessary to 

make reasonable progress may be either 

new, additional control measures for a 

source, or they may be the existing 

emission reduction measures that a 

source is already implementing. See 

2019 Guidance at 43; 2021 Clarifications 

Memo at 8–10. Such measures must be 

represented by ‘‘enforceable emissions 

limitations, compliance schedules, and 

other measures’’ (i.e., any additional 

compliance tools) in a state’s long-term 

strategy in its SIP. 40 CFR 51.308(f)(2). 

Section 51.308(f)(2)(i) provides the 

requirements for the four-factor 

analysis. The first step of this analysis 

entails selecting the sources to be 

evaluated for emission reduction 

measures; to this end, the RHR requires 

states to consider ‘‘major and minor 

stationary sources or groups of sources, 

mobile sources, and area sources’’ of 

visibility impairing pollutants for 

potential four-factor control analysis. 40 

CFR 51.308(f)(2)(i). A threshold 

question at this step is which visibility 

impairing pollutants will be analyzed. 

As EPA previously explained, 

consistent with the first implementation 

period, EPA generally expects that each 

state will analyze at least SO2 and NOX

in selecting sources and determining 

control measures. See 2019 Guidance at 

12, 2021 Clarifications Memo at 4. A 

state that chooses not to consider at 

least these two pollutants should 

demonstrate why such consideration 

would be unreasonable. 2021 

Clarifications Memo at 4. 

While states have the option to 

analyze all sources, the 2019 Guidance 

explains that ‘‘an analysis of control 

measures is not required for every 

source in each implementation period,’’ 

and that ‘‘[s]electing a set of sources for 

analysis of control measures in each 

implementation period is . . . 

consistent with the Regional Haze Rule, 

which sets up an iterative planning 

process and anticipates that a state may 

not need to analyze control measures for 

all its sources in a given SIP revision.’’ 

2019 Guidance at 9. However, given that 

source selection is the basis of all 

subsequent control determinations, a 

reasonable source selection process 

‘‘should be designed and conducted to 

ensure that source selection results in a 

set of pollutants and sources the 

evaluation of which has the potential to 

meaningfully reduce their contributions 

to visibility impairment.’’ 2021 

Clarifications Memo at 3. 

EPA explained in the 2021 

Clarifications Memo that each state has 

an obligation to submit a long-term 

strategy that addresses the regional haze 

visibility impairment that results from 

emissions from within that state. Thus, 

source selection should focus on the instate contribution to visibility 

impairment and be designed to capture 

a meaningful portion of the state’s total 

contribution to visibility impairment in 

Class I areas. A state should not decline 

to select its largest in-state sources on 

the basis that there are even larger outof-state contributors. 2021 Clarifications 

Memo at 4.20

Thus, while states have discretion to 

choose any source selection 

methodology that is reasonable, 

whatever choices they make should be 

reasonably explained. To this end, 40 

CFR 51.308(f)(2)(i) requires that a state’s 

SIP submission include ‘‘a description 

of the criteria it used to determine 

which sources or groups of sources it 

evaluated.’’ The technical basis for 

source selection, which may include 

methods for quantifying potential 

visibility impacts such as emissions 

divided by distance metrics, trajectory 

analyses, residence time analyses, and/ 

or photochemical modeling, must also 

be appropriately documented, as 

required by 40 CFR 51.308(f)(2)(iii). 

Once a state has selected the set of 

sources, the next step is to determine 

the emissions reduction measures for 

those sources that are necessary to make 

reasonable progress for the second 

implementation period.21 This is 

accomplished by considering the four 

factors—‘‘the costs of compliance, the 

time necessary for compliance, and the 

energy and non-air quality 

environmental impacts of compliance, 

and the remaining useful life of any 

existing source subject to such 

requirements.’’ CAA 169A(g)(1). The 

EPA has explained that the four-factor 

analysis is an assessment of potential 

emission reduction measures (i.e., 

control options) for sources; ‘‘use of the 

terms ‘compliance’ and ‘subject to such 

requirements’ in section 169A(g)(1) 

strongly indicates that Congress 

intended the relevant determination to 

be the requirements with which sources 

would have to comply in order to satisfy 

the CAA’s reasonable progress 

mandate.’’ 82 FR at 3091. Thus, for each 

source it has selected for four-factor 

analysis,22 a state must consider a 

‘‘meaningful set’’ of technically feasible 

control options for reducing emissions 

of visibility impairing pollutants. Id. at 

3088. The 2019 Guidance provides that 

‘‘[a] state must reasonably pick and 

justify the measures that it will 

consider, recognizing that there is no 

statutory or regulatory requirement to 

consider all technically feasible 

measures or any particular measures. A 

range of technically feasible measures 

available to reduce emissions would be 

one way to justify a reasonable set.’’ 

2019 Guidance at 29. 

EPA’s 2021 Clarifications Memo 

provides further guidance on what 

constitutes a reasonable set of control 

options for consideration: ‘‘A reasonable 

four-factor analysis will consider the 

full range of potentially reasonable 

options for reducing emissions.’’ 2021 

Clarifications Memo at 7. In addition to 

add-on controls and other retrofits (i.e., 

new emission reduction measures for 

sources), EPA explained that states 

should generally analyze efficiency 

improvements for sources’ existing 

measures as control options in their 

four-factor analyses, as in many cases 


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23See, e.g., Responses to Comments on Protection 

of Visibility: Amendments to Requirements for 

State Plans; Proposed Rule (81 FR 26942, May 4, 

2016), Docket Number EPA–HQ–OAR–2015–0531, 

U.S. Environmental Protection Agency at 186; 2019 

Guidance at 36–37. 

24States may choose to, but are not required to, 

include measures in their long-term strategies 

beyond just the emission reduction measures that 

are necessary for reasonable progress. See 2021 

Clarifications Memo at 16. For example, states with 

smoke management programs may choose to submit 

their smoke management plans to EPA for inclusion 

in their SIPs but are not required to do so. See, e.g., 

82 FR at 3108–09 (requirement to consider smoke 

management practices and smoke management 

programs under 40 CFR 51.308(f)(2)(iv) does not 

require states to adopt such practices or programs 

into their SIPs, although they may elect to do so). 

25See Arizona ex rel. Darwin v. U.S. EPA, 815 

F.3d 519, 531 (9th Cir. 2016); Nebraska v. U.S. EPA, 

812 F.3d 662, 668 (8th Cir. 2016); North Dakota v. 

EPA, 730 F.3d 750, 761 (8th Cir. 2013); Oklahoma 

v. EPA, 723 F.3d 1201, 1206, 1208–10 (10th Cir. 

2013); cf. also Alaska Dep’t of Envtl. Conservation 

v. EPA, 540 U.S. 461, 485, 490 (2004); Nat’l Parks 

Conservation Ass’n v. EPA, 803 F.3d 151, 165 (3d 

Cir. 2015). 

such improvements are reasonable given 

that they typically involve only 

additional operation and maintenance 

costs. Additionally, the 2021 

Clarifications Memo provides that states 

that have assumed a higher emission 

rate than a source has achieved or could 

potentially achieve using its existing 

measures should also consider lower 

emission rates as potential control 

options. That is, a state should consider 

a source’s recent actual and projected 

emission rates to determine if it could 

reasonably attain lower emission rates 

with its existing measures. If so, the 

state should analyze the lower emission 

rate as a control option for reducing 

emissions. 2021 Clarifications Memo at 

7. The EPA’s recommendations to 

analyze potential efficiency 

improvements and achievable lower 

emission rates apply to both sources 

that have been selected for four-factor 

analysis and those that have forgone a 

four-factor analysis on the basis of 

existing ‘‘effective controls.’’ See 2021 

Clarifications Memo at 5, 10. 

After identifying a reasonable set of 

potential control options for the sources 

it has selected, a state then collects 

information on the four factors with 

regard to each option identified. The 

EPA has also explained that, in addition 

to the four statutory factors, states have 

flexibility under the CAA and RHR to 

reasonably consider visibility benefits as 

an additional factor alongside the four 

statutory factors.23 The 2019 Guidance 

provides recommendations for the types 

of information that can be used to 

characterize the four factors (with or 

without visibility), as well as ways in 

which states might reasonably consider 

and balance that information to 

determine which of the potential control 

options is necessary to make reasonable 

progress. See 2019 Guidance at 30–36. 

The 2021 Clarifications Memo contains 

further guidance on how states can 

reasonably consider modeled visibility 

impacts or benefits in the context of a 

four-factor analysis. 2021 Clarifications 

Memo at 12–13, 14–15. Specifically, 

EPA explained that while visibility can 

reasonably be used when comparing 

and choosing between multiple 

reasonable control options, it should not 

be used to summarily reject controls 

that are reasonable given the four 

statutory factors. 2021 Clarifications 

Memo at 13. Ultimately, while states 

have discretion to reasonably weigh the 

factors and to determine what level of 

control is needed, § 51.308(f)(2)(i) 

provides that a state ‘‘must include in 

its implementation plan a description of 

. . . how the four factors were taken 

into consideration in selecting the 

measure for inclusion in its long-term 

strategy.’’ 

As explained above, § 51.308(f)(2)(i) 

requires states to determine the 

emission reduction measures for sources 

that are necessary to make reasonable 

progress by considering the four factors. 

Pursuant to § 51.308(f)(2), measures that 

are necessary to make reasonable 

progress towards the national visibility 

goal must be included in a state’s longterm strategy and in its SIP.24 If the 

outcome of a four-factor analysis is a 

new, additional emission reduction 

measure for a source, that new measure 

is necessary to make reasonable progress 

towards remedying existing 

anthropogenic visibility impairment and 

must be included in the SIP. If the 

outcome of a four-factor analysis is that 

no new measures are reasonable for a 

source, continued implementation of 

the source’s existing measures is 

generally necessary to prevent future 

emission increases and thus to make 

reasonable progress towards the second 

part of the national visibility goal: 

preventing future anthropogenic 

visibility impairment. See CAA 

169A(a)(1). That is, when the result of 

a four-factor analysis is that no new 

measures are necessary to make 

reasonable progress, the source’s 

existing measures are generally 

necessary to make reasonable progress 

and must be included in the SIP. 

However, there may be circumstances in 

which a state can demonstrate that a 

source’s existing measures are not 

necessary to make reasonable progress. 

Specifically, if a state can demonstrate 

that a source will continue to 

implement its existing measures and 

will not increase its emission rate, it 

may not be necessary to have those 

measures in the long-term strategy in 

order to prevent future emission 

increases and future visibility 

impairment. EPA’s 2021 Clarifications 

Memo provides further explanation and 

guidance on how states may 

demonstrate that a source’s existing 

measures are not necessary to make 

reasonable progress. See 2021 

Clarifications Memo at 8–10. If the state 

can make such a demonstration, it need 

not include a source’s existing measures 

in the long-term strategy or its SIP. 

As with source selection, the 

characterization of information on each 

of the factors is also subject to the 

documentation requirement in 

§ 51.308(f)(2)(iii). The reasonable 

progress analysis, including source 

selection, information gathering, 

characterization of the four statutory 

factors (and potentially visibility), 

balancing of the four factors, and 

selection of the emission reduction 

measures that represent reasonable 

progress, is a technically complex 

exercise, but also a flexible one that 

provides states with bounded discretion 

to design and implement approaches 

appropriate to their circumstances. 

Given this flexibility, § 51.308(f)(2)(iii) 

plays an important function in requiring 

a state to document the technical basis 

for its decision making so that the 

public and the EPA can comprehend 

and evaluate the information and 

analysis the state relied upon to 

determine what emission reduction 

measures must be in place to make 

reasonable progress. The technical 

documentation must include the 

modeling, monitoring, cost, engineering, 

and emissions information on which the 

state relied to determine the measures 

necessary to make reasonable progress. 

This documentation requirement can be 

met through the provision of and 

reliance on technical analyses 

developed through a regional planning 

process, so long as that process and its 

output has been approved by all state 

participants. In addition to the explicit 

regulatory requirement to document the 

technical basis of their reasonable 

progress determinations, states are also 

subject to the general principle that 

those determinations must be 

reasonably moored to the statute.25 That 

is, a state’s decisions about the emission 

reduction measures that are necessary to 

make reasonable progress must be 

consistent with the statutory goal of 

remedying existing and preventing 

future visibility impairment. 

The four statutory factors (and 

potentially visibility) are used to 

determine what emission reduction 


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26The five ‘‘additional factors’’ for consideration 

in section 51.308(f)(2)(iv) are distinct from the four 

factors listed in CAA section 169A(g)(1) and 40 CFR 

51.308(f)(2)(i) that states must consider and apply 

to sources in determining reasonable progress. 

27RPGs are intended to reflect the projected 

impacts of the measures all contributing states 

include in their long-term strategies. However, due 

to the timing of analyses and of control 

determinations by other states, other on-going 

emissions changes, a particular state’s RPGs may 

not reflect all control measures and emissions 

reductions that are expected to occur by the end of 

the implementation period. The 2019 Guidance 

provides recommendations for addressing the 

timing of RPG calculations when states are 

developing their long-term strategies on disparate 

schedules, as well as for adjusting RPGs using a 

post-modeling approach. 2019 Guidance at 47–48. 

measures for selected sources must be 

included in a state’s long-term strategy 

for making reasonable progress. 

Additionally, the RHR at 40 CFR 

51.3108(f)(2)(iv) separately provides five 

‘‘additional factors’’ 26 that states must 

consider in developing their long-term 

strategies: (1) Emission reductions due 

to ongoing air pollution control 

programs, including measures to 

address reasonably attributable visibility 

impairment; (2) measures to reduce the 

impacts of construction activities; (3) 

source retirement and replacement 

schedules; (4) basic smoke management 

practices for prescribed fire used for 

agricultural and wildland vegetation 

management purposes and smoke 

management programs; and (5) the 

anticipated net effect on visibility due to 

projected changes in point, area, and 

mobile source emissions over the period 

addressed by the long-term strategy. The 

2019 Guidance provides that a state may 

satisfy this requirement by considering 

these additional factors in the process of 

selecting sources for four-factor 

analysis, when performing that analysis, 

or both, and that not every one of the 

additional factors needs to be 

considered at the same stage of the 

process. See 2019 Guidance at 21. EPA 

provided further guidance on the five 

additional factors in the 2021 

Clarifications Memo, explaining that a 

state should generally not reject costeffective and otherwise reasonable 

controls merely because there have been 

emission reductions since the first 

planning period owing to other ongoing 

air pollution control programs or merely 

because visibility is otherwise projected 

to improve at Class I areas. 

Additionally, states generally should 

not rely on these additional factors to 

summarily assert that the state has 

already made sufficient progress and, 

therefore, no sources need to be selected 

or no new controls are needed 

regardless of the outcome of four-factor 

analyses. 2021 Clarifications Memo at 

13. 

Because the air pollution that causes 

regional haze crosses state boundaries, 

§ 51.308(f)(2)(ii) requires a state to 

consult with other states that also have 

emissions that are reasonably 

anticipated to contribute to visibility 

impairment in a given Class I area. 

Consultation allows for each state that 

impacts visibility in an area to share 

whatever technical information, 

analyses, and control determinations 

may be necessary to develop 

coordinated emission management 

strategies. This coordination may be 

managed through inter- and intra-RPO 

consultation and the development of 

regional emissions strategies; additional 

consultations between states outside of 

RPO processes may also occur. If a state, 

pursuant to consultation, agrees that 

certain measures (e.g., a certain 

emission limitation) are necessary to 

make reasonable progress at a Class I 

area, it must include those measures in 

its SIP. 40 CFR 51.308(f)(2)(ii)(A). 

Additionally, the RHR requires that 

states that contribute to visibility 

impairment at the same Class I area 

consider the emission reduction 

measures the other contributing states 

have identified as being necessary to 

make reasonable progress for their own 

sources. 40 CFR 51.308(f)(2)(ii)(B). If a 

state has been asked to consider or 

adopt certain emission reduction 

measures, but ultimately determines 

those measures are not necessary to 

make reasonable progress, that state 

must document in its SIP the actions 

taken to resolve the disagreement. 40 

CFR 51.308(f)(2)(ii)(C). The EPA will 

consider the technical information and 

explanations presented by the 

submitting state and the state with 

which it disagrees when considering 

whether to approve the state’s SIP. See 

id.; 2019 Guidance at 53. Under all 

circumstances, a state must document in 

its SIP submission all substantive 

consultations with other contributing 

states. 40 CFR 51.308(f)(2)(ii)(C). 

D. Reasonable Progress Goals 

Reasonable progress goals ‘‘measure 

the progress that is projected to be 

achieved by the control measures states 

have determined are necessary to make 

reasonable progress based on a fourfactor analysis.’’ 82 FR at 3091. Their 

primary purpose is to assist the public 

and the EPA in assessing the 

reasonableness of states’ long-term 

strategies for making reasonable 

progress towards the national visibility 

goal. See 40 CFR 51.308(f)(3)(iii)-(iv). 

States in which Class I areas are located 

must establish two RPGs, both in 

deciviews—one representing visibility 

conditions on the clearest days and one 

representing visibility on the most 

anthropogenically impaired days—for 

each area within their borders. 40 CFR 

51.308(f)(3)(i). The two RPGs are 

intended to reflect the projected 

impacts, on the two sets of days, of the 

emission reduction measures the state 

with the Class I area, as well as all other 

contributing states, have included in 

their long-term strategies for the second 

implementation period.27 The RPGs also 

account for the projected impacts of 

implementing other CAA requirements, 

including non-SIP based requirements. 

Because RPGs are the modeled result of 

the measures in states’ long-term 

strategies (as well as other measures 

required under the CAA), they cannot 

be determined before states have 

conducted their four-factor analyses and 

determined the control measures that 

are necessary to make reasonable 

progress. See 2021 Clarifications Memo 

at 6. 

For the second implementation 

period, the RPGs are set for 2028. 

Reasonable progress goals are not 

enforceable targets, 40 CFR 

51.308(f)(3)(iii); rather, they ‘‘provide a 

way for the states to check the projected 

outcome of the [long-term strategy] 

against the goals for visibility 

improvement.’’ 2019 Guidance at 46. 

While states are not legally obligated to 

achieve the visibility conditions 

described in their RPGs, § 51.308(f)(3)(i) 

requires that ‘‘[t]he long-term strategy 

and the reasonable progress goals must 

provide for an improvement in visibility 

for the most impaired days since the 

baseline period and ensure no 

degradation in visibility for the clearest 

days since the baseline period.’’ Thus, 

states are required to have emission 

reduction measures in their long-term 

strategies that are projected to achieve 

visibility conditions on the most 

impaired days that are better than the 

baseline period and show no 

degradation on the clearest days 

compared to the clearest days from the 

baseline period. The baseline period for 

the purpose of this comparison is the 

baseline visibility condition—the 

annual average visibility condition for 

the period 2000–2004. See 40 CFR 

51.308(f)(1)(i), 82 FR at 3097–98. 

So that RPGs may also serve as a 

metric for assessing the amount of 

progress a state is making towards the 

national visibility goal, the RHR 

requires states with Class I areas to 

compare the 2028 RPG for the most 

impaired days to the corresponding 

point on the URP line (representing 

visibility conditions in 2028 if visibility 


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28See ‘‘Step 8: Additional requirements for 

regional haze SIPs’’ in 2019 Regional Haze 

Guidance at 55. 

29 Id. 

30EPA’s visibility protection regulations define 

‘‘reasonably attributable visibility impairment’’ as 

‘‘visibility impairment that is caused by the 

emission of air pollutants from one, or a small 

number of sources.’’ 40 CFR 51.301. 

were to improve at a linear rate from 

conditions in the baseline period of 

2000–2004 to natural visibility 

conditions in 2064). If the most 

impaired days RPG in 2028 is above the 

URP (i.e., if visibility conditions are 

improving more slowly than the rate 

described by the URP), each state that 

contributes to visibility impairment in 

the Class I area must demonstrate, based 

on the four-factor analysis required 

under 40 CFR 51.308(f)(2)(i), that no 

additional emission reduction measures 

would be reasonable to include in its 

long-term strategy. 40 CFR 

51.308(f)(3)(ii). To this end, 40 CFR 

51.308(f)(3)(ii) requires that each state 

contributing to visibility impairment in 

a Class I area that is projected to 

improve more slowly than the URP 

provide ‘‘a robust demonstration, 

including documenting the criteria used 

to determine which sources or groups 

[of] sources were evaluated and how the 

four factors required by paragraph 

(f)(2)(i) were taken into consideration in 

selecting the measures for inclusion in 

its long-term strategy.’’ The 2019 

Guidance provides suggestions about 

how such a ‘‘robust demonstration’’ 

might be conducted. See 2019 Guidance 

at 50–51. 

The 2017 RHR, 2019 Guidance, and 

2021 Clarifications Memo also explain 

that projecting an RPG that is on or 

below the URP based on only on-thebooks and/or on-the-way control 

measures (i.e., control measures already 

required or anticipated before the fourfactor analysis is conducted) is not a 

‘‘safe harbor’’ from the CAA’s and RHR’s 

requirement that all states must conduct 

a four-factor analysis to determine what 

emission reduction measures constitute 

reasonable progress. The URP is a 

planning metric used to gauge the 

amount of progress made thus far and 

the amount left before reaching natural 

visibility conditions. However, the URP 

is not based on consideration of the four 

statutory factors and therefore cannot 

answer the question of whether the 

amount of progress being made in any 

particular implementation period is 

‘‘reasonable progress.’’ See 82 FR at 

3093, 3099–3100; 2019 Guidance at 22; 

2021 Clarifications Memo at 15–16. 

E. Monitoring Strategy and Other State 

Implementation Plan Requirements 

Section 51.308(f)(6) requires states to 

have certain strategies and elements in 

place for assessing and reporting on 

visibility. Individual requirements 

under this subsection apply either to 

states with Class I areas within their 

borders, states with no Class I areas but 

that are reasonably anticipated to cause 

or contribute to visibility impairment in 

any Class I area, or both. A state with 

Class I areas within its borders must 

submit with its SIP revision a 

monitoring strategy for measuring, 

characterizing, and reporting regional 

haze visibility impairment that is 

representative of all Class I areas within 

the state. SIP revisions for such states 

must also provide for the establishment 

of any additional monitoring sites or 

equipment needed to assess visibility 

conditions in Class I areas, as well as 

reporting of all visibility monitoring 

data to the EPA at least annually. 

Compliance with the monitoring 

strategy requirement may be met 

through a state’s participation in the 

Interagency Monitoring of Protected 

Visual Environments (IMPROVE) 

monitoring network, which is used to 

measure visibility impairment caused 

by air pollution at the 156 Class I areas 

covered by the visibility program. 40 

CFR 51.308(f)(6), (f)(6)(i), (f)(6)(iv). The 

IMPROVE monitoring data is used to 

determine the 20% most 

anthropogenically impaired and 20% 

clearest sets of days every year at each 

Class I area and tracks visibility 

impairment over time. 

All states’ SIPs must provide for 

procedures by which monitoring data 

and other information are used to 

determine the contribution of emissions 

from within the state to regional haze 

visibility impairment in affected Class I 

areas. 40 CFR 51.308(f)(6)(ii), (iii). 

Section 51.308(f)(6)(v) further requires 

that all states’ SIPs provide for a 

statewide inventory of emissions of 

pollutants that are reasonably 

anticipated to cause or contribute to 

visibility impairment in any Class I area; 

the inventory must include emissions 

for the most recent year for which data 

are available and estimates of future 

projected emissions. States must also 

include commitments to update their 

inventories periodically. The 

inventories themselves do not need to 

be included as elements in the SIP and 

are not subject to EPA review as part of 

the Agency’s evaluation of a SIP 

revision.28 All states’ SIPs must also 

provide for any other elements, 

including reporting, recordkeeping, and 

other measures, that are necessary for 

states to assess and report on visibility. 

40 CFR 51.308(f)(6)(vi). Per the 2019 

Guidance, a state may note in its 

regional haze SIP that its compliance 

with the Air Emissions Reporting Rule 

(AERR) in 40 CFR part 51 Subpart A 

satisfies the requirement to provide for 

an emissions inventory for the most 

recent year for which data are available. 

To satisfy the requirement to provide 

estimates of future projected emissions, 

a state may explain in its SIP how 

projected emissions were developed for 

use in establishing RPGs for its own and 

nearby Class I areas.29

Separate from the requirements 

related to monitoring for regional haze 

purposes under 40 CFR 51.308(f)(6), the 

RHR also contains a requirement at 

§ 51.308(f)(4) related to any additional 

monitoring that may be needed to 

address visibility impairment in Class I 

areas from a single source or a small 

group of sources. This is called 

‘‘reasonably attributable visibility 

impairment.’’ 30 Under this provision, if 

the EPA or the FLM of an affected Class 

I area has advised a state that additional 

monitoring is needed to assess 

reasonably attributable visibility 

impairment, the state must include in 

its SIP revision for the second 

implementation period an appropriate 

strategy for evaluating such impairment. 

F. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

Section 51.308(f)(5) requires a state’s 

regional haze SIP revision to address the 

requirements of paragraphs 40 CFR 

51.308(g)(1) through (5) so that the plan 

revision due in 2021 will serve also as 

a progress report addressing the period 

since submission of the progress report 

for the first implementation period. The 

regional haze progress report 

requirement is designed to inform the 

public and the EPA about a state’s 

implementation of its existing long-term 

strategy and whether such 

implementation is in fact resulting in 

the expected visibility improvement. 

See 81 FR 26942, 26950 (May 4, 2016), 

(82 FR at 3119, January 10, 2017). To 

this end, every state’s SIP revision for 

the second implementation period is 

required to describe the status of 

implementation of all measures 

included in the state’s long-term 

strategy, including BART and 

reasonable progress emission reduction 

measures from the first implementation 

period, and the resulting emissions 

reductions. 40 CFR 51.308(g)(1) and (2). 

A core component of the progress 

report requirements is an assessment of 

changes in visibility conditions on the 

clearest and most impaired days. For 

second implementation period progress 

reports, § 51.308(g)(3) requires states 


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31Massachusetts supplemented its SIP 

submission on June 15, 2022. 

32The contribution assessment methodologies for 

MANE–VU Class I areas are summarized in MA RH 

SIP Appendix 16 of the docket. ‘‘Selection of States 

for MANE–VU Regional Haze Consultation (2018),’’ 

MANE–VU TSC. September 5, 2017. 

with Class I areas within their borders 

to first determine current visibility 

conditions for each area on the most 

impaired and clearest days, 40 CFR 

51.308(g)(3)(i)(B), and then to calculate 

the difference between those current 

conditions and baseline (2000–2004) 

visibility conditions in order to assess 

progress made to date. See 40 CFR 

51.308(g)(3)(ii)(B). States must also 

assess the changes in visibility 

impairment for the most impaired and 

clearest days since they submitted their 

first implementation period progress 

reports. See 40 CFR 51.308(g)(3)(iii)(B), 

(f)(5). Since different states submitted 

their first implementation period 

progress reports at different times, the 

starting point for this assessment will 

vary state by state. 

Similarly, states must provide 

analyses tracking the change in 

emissions of pollutants contributing to 

visibility impairment from all sources 

and activities within the state over the 

period since they submitted their first 

implementation period progress reports. 

See 40 CFR 51.308(g)(4), (f)(5). Changes 

in emissions should be identified by the 

type of source or activity. Section 

51.308(g)(5) also addresses changes in 

emissions since the period addressed by 

the previous progress report and 

requires states’ SIP revisions to include 

an assessment of any significant changes 

in anthropogenic emissions within or 

outside the state. This assessment must 

include an explanation of whether these 

changes in emissions were anticipated 

and whether they have limited or 

impeded progress in reducing emissions 

and improving visibility relative to what 

the state projected based on its longterm strategy for the first 

implementation period. 

G. Requirements for State and Federal 

Land Manager Coordination 

Clean Air Act section 169A(d) 

requires that before a state holds a 

public hearing on a proposed regional 

haze SIP revision, it must consult with 

the appropriate FLM or FLMs; pursuant 

to that consultation, the state must 

include a summary of the FLMs’ 

conclusions and recommendations in 

the notice to the public. Consistent with 

this statutory requirement, the RHR also 

requires that states ‘‘provide the [FLM] 

with an opportunity for consultation, in 

person and at a point early enough in 

the State’s policy analyses of its longterm strategy emission reduction 

obligation so that information and 

recommendations provided by the 

[FLM] can meaningfully inform the 

State’s decisions on the long-term 

strategy.’’ 40 CFR 51.308(i)(2). 

Consultation that occurs 120 days prior 

to any public hearing or public 

comment opportunity will be deemed 

‘‘early enough,’’ but the RHR provides 

that in any event the opportunity for 

consultation must be provided at least 

60 days before a public hearing or 

comment opportunity. This consultation 

must include the opportunity for the 

FLMs to discuss their assessment of 

visibility impairment in any Class I area 

and their recommendations on the 

development and implementation of 

strategies to address such impairment. 

40 CFR 51.308(i)(2). In order for the EPA 

to evaluate whether FLM consultation 

meeting the requirements of the RHR 

has occurred, the SIP submission should 

include documentation of the timing 

and content of such consultation. The 

SIP revision submitted to the EPA must 

also describe how the state addressed 

any comments provided by the FLMs. 

40 CFR 51.308(i)(3). Finally, a SIP 

revision must provide procedures for 

continuing consultation between the 

state and FLMs regarding the state’s 

visibility protection program, including 

development and review of SIP 

revisions, five-year progress reports, and 

the implementation of other programs 

having the potential to contribute to 

impairment of visibility in Class I areas. 

40 CFR 51.308(i)(4). 

IV. The EPA’s Evaluation of 

Massachusetts’ Regional Haze 

Submission for the Second 

Implementation Period 

A. Background on Massachusetts’ First 

Implementation Period SIP Submission 

MassDEP submitted its regional haze 

SIP for the first implementation period 

to the EPA on July 28, 2009, and 

supplemented it on December 9, 2010, 

March 2, 2011, and December 7, 2011. 

The EPA approved Massachusetts’ first 

implementation period regional haze 

SIP submission on September 19, 2013 

(78 FR 57487). EPA’s approval included, 

but was not limited to, the portions of 

the plan that address the reasonable 

progress requirements, Massachusetts’ 

implementation of Best Available 

Retrofit Technologies on eligible 

sources, and Massachusetts’ 310 CMR 

7.05 ‘‘Fuels All Districts;’’ Sulfur in 

Fuels rule. The requirements for 

regional haze SIPs for the first 

implementation period are contained in 

40 CFR 51.308(d) and (e). 40 CFR 

51.308(b). Pursuant to 40 CFR 51.308(g), 

Massachusetts was also responsible for 

submitting a five-year progress report as 

a SIP revision for the first 

implementation period, which it did on 

February 9, 2018. The EPA approved the 

progress report into the Massachusetts 

SIP on March 29, 2019 (84 FR 11885). 

B. Massachusetts’ Second 

Implementation Period SIP Submission 

and the EPA’s Evaluation 

In accordance with CAA sections 

169A and the RHR at 40 CFR 51.308(f), 

on July 22, 2021,31 Massachusetts 

submitted a revision to the 

Massachusetts SIP to address its 

regional haze obligations for the second 

implementation period, which runs 

through 2028. Massachusetts made a 

draft Regional Haze SIP submission 

available for public comment on April 

7, 2021. Massachusetts has included the 

public comments and its responses to 

those comments in the submission. 

The following sections describe 

Massachusetts’ SIP submission, 

including analyses conducted by 

MANE–VU and Massachusetts’ 

determinations based on those analyses, 

Massachusetts’ assessment of progress 

made since the first implementation 

period in reducing emissions of 

visibility impairing pollutants, and the 

visibility improvement progress at 

nearby Class I areas. This notice also 

contains EPA’s evaluation of 

Massachusetts’ submission against the 

requirements of the CAA and RHR for 

the second implementation period of 

the regional haze program. 

C. Identification of Class I Areas 

Section 169A(b)(2) of the CAA 

requires each state in which any Class 

I area is located or ‘‘the emissions from 

which may reasonably be anticipated to 

cause or contribute to any impairment 

of visibility’’ in a Class I area to have a 

plan for making reasonable progress 

toward the national visibility goal. The 

RHR implements this statutory 

requirement at 40 CFR 51.308(f), which 

provides that each state’s plan ‘‘must 

address regional haze in each 

mandatory Class I Federal area located 

within the State and in each mandatory 

Class I Federal area located outside the 

State that may be affected by emissions 

from within the State,’’ and (f)(2), which 

requires each state’s plan to include a 

long-term strategy that addresses 

regional haze in such Class I areas. 

Massachusetts has no mandatory Class I 

Federal area within its borders. 

For the second implementation 

period, MANE–VU performed technical 

analyses 32 to help assess source and 

state-level contributions to visibility 

impairment and the need for interstate 

consultation. MANE–VU used the 


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33 Id. 

34See docket EPA–R01–OAR–2012–0025 for 

MANE–VU supporting materials. 

35 ‘‘Q/d’’ is emissions (Q) in tons per year, 

typically of one or a combination of visibilityimpairing pollutants, divided by distance to a class 

I area (d) in kilometers. The resulting ratio is 

commonly used as a metric to assess a source’s 

potential visibility impacts on a particular class I 

area. 

36See appendix 8 ‘‘2016 MANE–VU Source 

Contribution Modeling Report—CALPUFF 

Modeling of 

Large Electrical Generating Units and Industrial 

Sources.’’ MANE–VU TSC. April 4, 2017. 

37See Section 5.4, page 68, Massachusetts 

Regional Haze SIP Revision for 2018–2028 in the 

docket. 

results of these analyses to determine 

which states’ emissions ‘‘have a high 

likelihood of affecting visibility in 

MANE–VU’s Class I areas.’’ 33 Similar to 

metrics used in the first implementation 

period,34 MANE–VU used a greater than 

2 percent of sulfate plus nitrate 

emissions contribution criteria to 

determine whether emissions from 

individual jurisdictions within the 

region affected visibility in any Class I 

areas. The MANE–VU analyses for the 

second implementation period used a 

combination of data analysis 

techniques, including emissions data, 

distance from Class I areas, wind 

trajectories, and CALPUFF dispersion 

modeling. Although many of the 

analyses focused only on SO2 emissions 

and resultant particulate sulfate 

contributions to visibility impairment, 

some also incorporated NOX emissions 

to estimate particulate nitrate 

contributions. 

One MANE–VU analysis used for 

contribution assessment was CALPUFF 

air dispersion modeling. The CALPUFF 

model was used to estimate sulfate and 

nitrate formation and transport in 

MANE–VU and nearby regions 

originating from large electric generating 

unit (EGU) point sources and other large 

industrial and institutional sources in 

the eastern and central United States. 

Information from an initial round of 

CALPUFF modeling was collated for the 

444 EGUs that were determined to 

warrant further scrutiny based on their 

emissions of SO2 and NOX. The list of 

EGUs was based on an enhanced ‘‘Q/d’’ 

analysis 35 that considered recent SO2

emissions in the eastern United States 

and an analysis that adjusted previous 

2002 MANE–VU CALPUFF modeling by 

applying a ratio of 2011 to 2002 SO2

emissions. This list of sources was then 

enhanced by including the top five SO2

and NOX emission sources for 2011 for 

each state included in the modeling 

domain. A total of 311 EGU stacks (as 

opposed to individual units) were 

included in the CALPUFF modeling 

analysis. Initial information was also 

collected on the 50 industrial and 

institutional sources that, according to 

2011 Q/d analysis, contributed the most 

to visibility impact in each Class I area. 

The ultimate CALPUFF modeling run 

included a total of 311 EGU stacks and 

82 industrial facilities. The summary 

report for the CALPUFF modeling 

included the top 10 most impacting 

EGUs and the top 5 most impacting 

industrial/institutional sources for each 

Class I area and compiled those results 

into a ranked list of the most impacting 

EGUs and industrial sources at MANE– 

VU Class I areas.36 Overall, MANE–VU 

found that emission sources located 

close to Class I areas typically show 

higher visibility impacts than similarly 

sized facilities further away. But 

visibility degradation appears to be 

dominated by the more distant emission 

sources due to their larger emissions. 

Massachusetts had five EGUs and one 

industrial source that were identified in 

the MANE–VU CALPUFF modeling as 

having a magnitude of emissions located 

close enough to a Class I area that they 

could have the potential for visibility 

impacts.37

Of the six sources, four were units at 

Brayton Point Power Station, a coalfired EGU facility (ORISPL 01619; 

MassDEP AQID 1200061). All four units 

at Brayton Point ceased operation in 

2017 and the permits were revoked on 

December 6, 2017. 

Canal Station (ORISPL 1599; 

MassDEP AQID 1200054) operates the 

other EGU (Unit 1) identified by the 

modelling, and its greatest impact was 

to Acadia. Unit 1 is a Babcock & Wilcox 

boiler that fires No. 6 fuel oil, with a 

permitted maximum sulfur content of 

0.5 percent by weight (wt%) as the sole 

operational fuel, with No. 2 fuel oil as 

a startup/ignition fuel. Unit 1 has an 

approximate maximum heat input rate 

of 5,083 million British thermal units 

per hour (MMBtu/hr) and a generating 

capacity of approximately 560 (net) 

megawatts (MW). Unit 1 is equipped 

with low-NOX burners, overfire air 

ports, flue gas recirculation (FGR), and 

Selective Catalytic Reduction (SCR) for 

the control of NOX emissions. PM 

emissions are controlled by an 

Electrostatic Precipitator (ESP). 

The emission controls installed on 

Unit 1 are necessary to achieve 

compliance with the applicable 

emission limits under 310 CMR 7.29 

and Air Plan Approvals (i.e., state air 

permits) issued pursuant to 310 CMR 

7.02 

Massachusetts concludes that 

visibility impairing pollutants from 

Canal Unit 1 are currently well 

controlled; however, Canal has 

committed to purchasing 0.3 wt% No. 6 

fuel oil following the depletion of the 

current fuel inventory. Therefore, 

Massachusetts asked the owner of Canal 

Unit 1 to submit an application to 

modify its plan approval to require use 

of 0.3% sulfur content oil. 

Massachusetts approved the plan 

application May 26, 2022, and 

submitted the plan approval to EPA for 

approval into the SIP as a supplement 

to the Regional Haze SIP Revision for 

Massachusetts on June 15, 2022. If Canal 

Unit 1 should operate above 10% 

capacity factor in the future, existing 

NOX RACT regulations (310 CMR 7.19) 

will further limit the NOX emissions. 

From 2013 through 2022, Canal Unit 

one capacity had a weighted average of 

2% capacity per year, with a low of 

0.1% to a high of 7% capacity 

utilization by year and emitted an 

average of 42 tons of NOX per year, 

ranging from a low of 2 tons to a high 

of 201 tons per year. Massachusetts will 

evaluate any changes in the operation of 

Canal Unit 1 in the next progress report. 

The only Massachusetts industrial 

source deemed by MANE–VU to have 

the potential for significant impact on 

Class I areas in 2011 was Solutia, Inc., 

which at the time was a coal- and oilfired chemical plant. Solutia’s greatest 

impact was to Lye Brook, and it ranked 

14th in the list of industrial/ 

institutional sources that had potential 

impacts on Lye Brook, based primarily 

on its SO2 emissions. MANE–VU 

estimated maximum extinction for 

Solutia at Lye Brook to be less than 1 

Mm-1. As reflected in the current Title 

V permit for the facility (Permit 

Transmittal No.: X229245), Solutia has 

since repowered from coal/oil to natural 

gas and is therefore no longer a 

significant source of SO2. 

As explained above, the EPA 

concluded in the 1999 RHR that ‘‘all 

[s]tates contain sources whose 

emissions are reasonably anticipated to 

contribute to regional haze in a Class I 

area,’’ 64 FR at 35721, and this 

determination was not changed in the 

2017 RHR. Critically, the statute and 

regulation both require that the causeor-contribute assessment consider all 

emissions of visibility-impairing 

pollutants from a state, as opposed to 

emissions of a particular pollutant or 

emissions from a certain set of sources. 

Consistent with these requirements, the 

2019 Guidance makes it clear that ‘‘all 

types of anthropogenic sources are to be 

included in the determination’’ of 

whether a state’s emissions are 

reasonably anticipated to result in any 

visibility impairment. 2019 Guidance at 

8. 


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38The Class I areas analyzed were Acadia 

National Park in Maine, Brigantine Wilderness in 

New Jersey, Great Gulf Wilderness and Presidential 

Range—Dry River Wilderness in New Hampshire, 

Lye Brook Wilderness in Vermont, Moosehorn 

Wilderness in Maine, Roosevelt Campobello 

International Park in New Brunswick, Shenandoah 

National Park in Virginia, James River Face 

Wilderness in Virginia, and Dolly Sods/Otter Creek 

Wildernesses in West Virginia. 

39As explained more fully in Section IV.E.a, 

MANE–VU refers to each of the components of its 

overall strategy as an ‘‘Ask ‘‘of its member states. 

40The MANE–VU consultation report (Appendix 

20) explains that ‘‘[t]he objective of this technical 

work was to identify states and sources from which 

MANE–VU will pursue further analysis. This 

screening was intended to identify which states to 

invite to consultation, not a definitive list of which 

states are contributing.’’ 

41Because MANE–VU did not include all of 

Massachusetts’ emissions or contributions to 

visibility impairment in its analysis, we cannot 

definitively state that Massachusetts’ contribution 

to visibility impairment is not the most significant. 

However, that is very likely the case. 

42See Section 6.3 Implementing the 2017 MANE– 

VU Statement. 

43See Appendix 22 ‘‘Mid-Atlantic/Northeast U.S. 

Visibility Data, 2004–2019 (2nd RH SIP Metrics). 

MANE–VU (prepared by Maine Department of 

Environmental Protection). January 21, 2021 

revision.’’ 

The screening analyses on which 

MANE–VU relied are useful for certain 

purposes. MANE–VU used information 

from its technical analysis to rank the 

largest contributing states to sulfate and 

nitrate impairment in the seven MANE– 

VU Class I areas and three additional, 

nearby Class I areas.38 The rankings 

were used to determine upwind states 

that were deemed important to include 

in state-to-state consultation (based on 

an identified impact screening 

threshold). Additionally, large 

individual source impacts were used to 

target MANE–VU control analysis 

‘‘Asks’’ 39 of states and sources both 

within and upwind of MANE–VU.40

The EPA finds the nature of the analyses 

generally appropriate to support 

decisions on states with which to 

consult. However, we have cautioned 

that source selection methodologies that 

target the largest regional contributors to 

visibility impairment across multiple 

states may not be reasonable for a 

particular state if it results in few or no 

sources being selected for subsequent 

analysis. 2021 Clarifications Memo at 3. 

With regard to the analysis and 

determinations regarding 

Massachusetts’ contribution to visibility 

impairment at out-of-state Class I areas, 

the MANE–VU technical work focuses 

on the magnitude of visibility impacts 

from certain Massachusetts emissions 

on other nearby Class I areas. However, 

the analyses did not account for all 

emissions and all components of 

visibility impairment (e.g., primary PM 

emissions, and impairment from fine 

PM, elemental carbon, and organic 

carbon). In addition, Q/d analyses with 

a relatively simplistic accounting for 

wind trajectories and CALPUFF applied 

to a very limited set of EGUs and major 

industrial sources of SO2 and NOX are 

not scientifically rigorous tools capable 

of evaluating contribution to visibility 

impairment from all emissions in a 

state. The EPA agrees that the 

contribution to visibility impairment 

from Massachusetts’ emissions at nearby 

out-of-state Class I areas is smaller than 

that from numerous other MANE–VU 

states.41 While some MANE–VU states 

noted that the contributions from 

several states outside the MANE–VU 

region are significantly larger than its 

own, we again clarify that each state is 

obligated under the CAA and RHR to 

address regional haze visibility 

impairment resulting from emissions 

from within the state, irrespective of 

whether another state’s contribution is 

greater. See 2021 Clarifications Memo at 

3. Additionally, we note that the 2 

percent or greater sulfate-plus-nitrate 

threshold used to determine whether 

Massachusetts emissions contribute to 

visibility impairment at a particular 

Class I area may be higher than what 

EPA believes is an ‘‘extremely low 

triggering threshold’’ intended by the 

statute and regulations. In sum, based 

on the information provided, EPA 

generally agrees with the State’s 

conclusions that emissions from 

Massachusetts contribute to visibility 

impairment in the Class I areas in Maine 

and New Brunswick and have relatively 

small contributions to the other nearby 

Class I areas. However, due to the low 

triggering threshold implied by the Rule 

and the lack of rigorous modeling 

analyses, we do not necessarily agree 

with the level of the State’s 2% 

contribution threshold. 

Regardless, Massachusetts did 

determine that sources and emissions 

within the state contribute to visibility 

impairment at Class I areas in Maine 

and New Brunswick. Furthermore, the 

state took part in the emission control 

strategy consultation process as a 

member of MANE–VU. As part of that 

process, MANE–VU developed a set of 

emissions reduction measures identified 

as being necessary to make reasonable 

progress in the seven MANE–VU Class 

I areas. This strategy consists of six Asks 

for states within MANE–VU and five 

Asks for states outside the region that 

were found to impact visibility at Class 

I areas within MANE–VU.42

Massachusetts’ submission discusses 

each of the Asks and explains why or 

why not each is applicable and how it 

has complied with the relevant 

components of the emissions control 

strategy the MANE–VU states laid out. 

Massachusetts worked with MANE–VU 

to determine potential reasonable 

measures that could be implemented by 

2028, considering the cost of 

compliance, the time necessary for 

compliance, the energy and non-air 

quality environmental impacts, and the 

remaining useful life of any potentially 

affected sources. As discussed in further 

detail below, the EPA is proposing to 

find that Massachusetts has submitted a 

regional haze plan that meets the 

requirements of 40 CFR 51.308(f)(2) 

related to the development of a longterm strategy. Thus, we propose to find 

that Massachusetts has nevertheless 

satisfied the applicable requirements for 

making reasonable progress towards 

natural visibility conditions in Class I 

areas that may be affected by emissions 

from the state. 

D. Calculations of Baseline, Current, 

and Natural Visibility Conditions; 

Progress to Date; and the Uniform Rate 

of Progress 

Section 51.308(f)(1) requires states to 

determine the following for ‘‘each 

mandatory Class I Federal area located 

within the State’’: baseline visibility 

conditions for the most impaired and 

clearest days, natural visibility 

conditions for the most impaired and 

clearest days, progress to date for the 

most impaired and clearest days, the 

differences between current visibility 

conditions and natural visibility 

conditions, and the URP. This section 

also provides the option for states to 

propose adjustments to the URP line for 

a Class I area to account for visibility 

impacts from anthropogenic sources 

outside the United States and/or the 

impacts from wildland prescribed fires 

that were conducted for certain, 

specified objectives. 40 CFR 

51.308(f)(1)(vi)(B). 

Although Massachusetts has no Class 

I areas, emissions from Massachusetts 

sources contribute to visibility 

impairment in MANE–VU Class I areas. 

MANE–VU Class I areas as well as other 

nearby Class I areas that MANE–VU 

examined, are listed below. MANE–VU 

used certain areas (as noted below) to 

represent nearby Class I areas where 

monitors do not exist.43

The MANE–VU Class I Areas are Lye 

Brook Wilderness Area (Vermont), Great 

Gulf Wilderness Area (New Hampshire) 

(used to represent Presidential Range— 

Dry River Wilderness Area), Presidential 

Range—Dry River Wilderness Area 

(New Hampshire), Acadia National Park 

(Maine), Moosehorn Wildlife Refuge 

(Maine) (used to represent Roosevelt 


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44Massachusetts Regional Haze SIP submission at 

74. 

45See appendix 15 ‘‘MANE–VU Regional Haze 

Consultation Report and Consultation 

Documentation—Final.’’ 

46 Id. 

47 Id. 

48The period of 2012–2016 was the most recent 

period for which data were available at the time of 

analysis. 

Campobello International Park), 

Roosevelt Campobello International 

Park (New Brunswick, Canada), 

Brigantine Wildlife Refuge (New Jersey). 

Nearby Class I Areas consist of Dolly 

Sods Wilderness Area (West Virginia) 

(used to represent Otter Creek 

Wilderness Area), Otter Creek 

Wilderness Area (West Virginia), 

Shenandoah National Park (Virginia), 

and James River Face Wilderness Area 

(Virginia). 

E. Long-Term Strategy for Regional Haze 

a. Massachusetts’ Response to the Six 

MANE–VU Asks 

Each state having a Class I area within 

its borders or emissions that may affect 

visibility in a Class I area must develop 

a long-term strategy for making 

reasonable progress towards the 

national visibility goal. CAA 

§ 169A(b)(2)(B). As explained in the 

Background section of this notice, 

reasonable progress is achieved when 

all states contributing to visibility 

impairment in a Class I area are 

implementing the measures 

determined—through application of the 

four statutory factors to sources of 

visibility impairing pollutants—to be 

necessary to make reasonable progress. 

40 CFR 51.308(f)(2)(i). Each state’s longterm strategy must include the 

enforceable emission limitations, 

compliance schedules, and other 

measures that are necessary to make 

reasonable progress. 40 CFR 

51.308(f)(2). All new (i.e., additional) 

measures that are the outcome of fourfactor analyses are necessary to make 

reasonable progress and must be in the 

long-term strategy. If the outcome of a 

four-factor analysis and other measures 

necessary to make reasonable progress is 

that no new measures are reasonable for 

a source, that source’s existing measures 

are necessary to make reasonable 

progress, unless the state can 

demonstrate that the source will 

continue to implement those measures 

and will not increase its emission rate. 

Existing measures that are necessary to 

make reasonable progress must also be 

in the long-term strategy. In developing 

its long-term strategies, a state must also 

consider the five additional factors in 

§ 51.308(f)(2)(iv). As part of its 

reasonable progress determinations, the 

state must describe the criteria used to 

determine which sources or group of 

sources were evaluated (i.e., subjected 

to four-factor analysis) for the second 

implementation period and how the 

four factors were taken into 

consideration in selecting the emission 

reduction measures for inclusion in the 

long-term strategy. 40 CFR 

51.308(f)(2)(i). 

The following section summarizes 

how Massachusetts’ SIP submission 

addressed the requirements of 

§ 51.308(f)(2)(i); specifically, it describes 

MANE–VU’s development of the six 

Asks and how Massachusetts addressed 

each. Massachusetts considers the six 

Asks to comprise its long-term strategy 

for the second planning period to 

address regional haze visibility 

impairment for each mandatory Class I 

Federal area affected by emissions from 

Massachusetts. When developing the 

Asks with the other MANE–VU states 

and applying them to sources in 

Massachusetts, the Commonwealth 

considered the four statutory factors and 

the additional regulatory factors and 

identified emissions control measures 

necessary to make reasonable progress 

towards the goal of preventing of any 

future, and remedying any existing, 

anthropogenic visibility impairment in 

Class I areas affected by emissions from 

Massachusetts. The EPA’s evaluation of 

Massachusetts’ long-term strategy is 

contained in the following Section 

IV.E.b. Massachusetts’ SIP submission 

describes how it plans to meet the longterm strategy requirements defined by 

the state and MANE–VU as the 

‘‘Asks.’’ 44

States may rely on technical 

information developed by the RPOs of 

which they are members to select 

sources for four-factor analysis and to 

conduct that analysis, as well as to 

satisfy the documentation requirements 

under § 51.308(f). Where an RPO has 

performed source selection and/or fourfactor analyses (or considered the five 

additional factors in § 51.308(f)(2)(iv)) 

for its member states, those states may 

rely on the RPO’s analyses for the 

purpose of satisfying the requirements 

of § 51.308(f)(2)(i) so long as the states 

have a reasonable basis to do so and all 

state participants in the RPO process 

have approved the technical analyses. 

40 CFR 51.308(f)(2)(iii). States may also 

satisfy the requirement of 

§ 51.308(f)(2)(ii) to engage in interstate 

consultation with other states that have 

emissions that are reasonably 

anticipated to contribute to visibility 

impairment in a given Class I area under 

the auspices of intra- and inter-RPO 

engagement. 

Massachusetts is a member of the 

MANE–VU RPO and participated in the 

RPO’s regional approach to developing 

a strategy for making reasonable 

progress towards the national visibility 

goal in the MANE–VU Class I areas. 

MANE–VU’s strategy includes a 

combination of: (1) Measures for certain 

source sectors and groups of sectors that 

the RPO determined were reasonable for 

states to pursue, and (2) a request for 

member states to conduct four-factor 

analyses for individual sources that it 

identified as contributing to visibility 

impairment. MANE–VU refers to each of 

the components of its overall strategy as 

an Ask of its member states. On August 

25, 2017, the Executive Director of 

MANE–VU, on behalf of the MANE–VU 

states and tribal nations, signed a 

statement that identifies six emission 

reduction measures that comprise the 

Asks for the second implementation 

period.45 The Asks were ‘‘designed to 

identify reasonable emission reduction 

strategies that must be addressed by the 

states and tribal nations of MANE–VU 

through their regional haze SIP 

updates.’’ 46 The statement explains that 

‘‘[i]f any State cannot agree with or 

complete a Class I State’s Asks, the State 

must describe the actions taken to 

resolve the disagreement in the Regional 

Haze SIP.’’ 47

MANE–VU’s recommendations as to 

the appropriate control measures were 

based on technical analyses 

documented in the RPO’s reports and 

included as appendices to or referenced 

in Massachusetts’ regional haze SIP 

submission. One of the initial steps of 

MANE–VU’s technical analysis was to 

determine which visibility-impairing 

pollutants should be the focus of its 

efforts for the second implementation 

period. In the first implementation 

period, MANE–VU determined that 

sulfates were the most significant 

visibility impairing pollutant at the 

region’s Class I areas. To determine the 

impact of certain pollutants on visibility 

at Class I areas for the purpose of second 

implementation period planning, 

MANE–VU conducted an analysis 

comparing the pollutant contribution on 

the clearest and most impaired days in 

the baseline period (2000–2004) to the 

most recent period (2012–2016) 48 at 

MANE–VU and nearby Class I areas. 

MANE–VU found that while SO2

emissions were decreasing and visibility 

was improving, sulfates still made up 

the most significant contribution to 

visibility impairment at MANE–VU and 

nearby Class I areas. According to the 

analysis, NOX emissions have begun to 

play a more significant role in visibility 


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49See appendix 14 ‘‘MANE–VU Four Factor Data 

Collection Memo,’’ at 1, March 30, 2017. 

50See appendix 6 ‘‘2016 Updates to the 

Assessment of Reasonable Progress for Regional 

Haze in MANE–VU Class I Areas, Jan. 31, 2016.’’ 

51 Id. 

52See appendix 14 ‘‘Four Factor Data Collection 

Memo.’’ 53See appendix 10 ‘‘Status of the Top 167 Stacks 

from the 2008 MANE–VU Ask. July 2016.’’ 54See appendix 23 ‘‘Massachusetts Facilities 

Subject to Ask 1: EGUs >= 25MW with Controls.’’ 

impacts in recent years as SO2

emissions have decreased. The technical 

analyses used by Massachusetts are 

included in their submission and are as 

follows: 

• 2016 Updates to the Assessment of 

Reasonable Progress for Regional Haze 

in MANE–VU Class I Areas (MA 

Appendix 6); 

• Impact of Wintertime SCR/SNCR 

Optimization on Visibility Impairing 

Nitrate Precursor Emissions. November 

2017. (MA Appendix 17); 

• High Electric Demand Days and 

Visibility Impairment in MANE–VU. 

December 2017. (MA Appendix 18); 

• Benefits of Combined Heat and 

Power Systems for Reducing Pollutant 

Emissions in MANE–VU States. March 

2016. (MA Appendix 7); 

• 2016 MANE–VU Source 

Contribution Modeling Report— 

CALPUFF Modeling of Large Electrical 

Generating Units and Industrial Sources 

April 4, 2017 (MA Appendix 8); 

• Contribution Assessment 

Preliminary Inventory Analysis. October 

10, 2016. (MA Appendix 11); 

• Four-Factor Data Collection Memo. 

March 2017. (MA Appendix 14); 

• Status of the Top 167 Stacks from 

the 2008 MANE–VU Ask. July 2016. 

(MA Appendix 10). 

To support development of the Asks, 

MANE–VU gathered information on 

each of the four statutory factors for six 

source sectors it determined, based on 

an examination of annual emission 

inventories, ‘‘had emissions [of SO2

and/or NOX] that were reasonabl[y] 

anticipated to contribute to visibility 

degradation in MANE–VU:’’ electric 

generating units (EGUs), industrial/ 

commercial/institutional boilers (ICI 

boilers), cement kilns, heating oil, 

residential wood combustion, and 

outdoor wood combustion.49 MANE– 

VU also collected data on individual 

sources within the EGU, ICI boiler, and 

cement kiln sectors.50 Information for 

the six sectors included explanations of 

technically feasible control options for 

SO2 or NOX, illustrative costeffectiveness estimates for a range of 

model units and control options, sectorwide cost considerations, potential time 

frames for compliance with control 

options, potential energy and non-airquality environmental impacts of 

certain control options, and how the 

remaining useful lives of sources might 

be considered in a control analysis.51

Source-specific data included SO2

emissions 52 and existing controls 53 for 

certain existing EGUs, ICI boilers, and 

cement kilns. MANE–VU considered 

this information on the four factors as 

well as the analyses developed by the 

RPO’s Technical Support Committee 

when it determined specific emission 

reduction measures that were found to 

be reasonable for certain sources within 

two of the sectors it had examined— 

EGUs and ICI boilers. The Asks were 

based on this analysis and looked to 

either optimize the use of existing 

controls, have states conduct further 

analysis on EGU or ICI boilers with 

considerable visibility impacts, 

implement low sulfur fuel standards, or 

lock-in lower emission rates. 

MANE–VU Ask 1 is ‘‘Electric 

Generating Units (EGUs) with a 

nameplate capacity larger than or equal 

to 25 MW with already installed NOX

and/or SO2 controls—ensure the most 

effective use of control technologies on 

a year-round basis to consistently 

minimize emissions of haze precursors 

or obtain equivalent alternative 

emission reductions.’’ MANE–VU 

observed that EGUs often only run NOX

emissions controls to comply with 

ozone season trading programs and 

consequently, NOX sources may be 

uncontrolled during the winter and nonpeak summer days. MANE–VU found 

that: (1) running existing installed 

controls [selective catalytic reduction 

(SCR) and selective non-catalytic 

reduction (SNCR)] is one of the most 

cost-effective ways to control NOX

emissions from EGUs; and (2) that 

running existing controls year round 

could substantially reduce the NOX

emissions in many of the states upwind 

of Class I areas in MANE–VU that lead 

to visibility impairment during the 

winter from nitrates. MANE–VU 

included this as an emission 

management strategy because large 

EGUs had already been identified as 

dominant contributors to visibility 

impairment and the low cost of running 

already installed controls made it 

reasonable. 

Massachusetts identified 53 EGU 

units that meet the criteria of 25 MW or 

larger with installed controls.54

Massachusetts explained that all of 

these units have NOX controls and that 

the permits for these units set short-term 

NOX emissions limits in lbs/hr or 

concentration, which are promulgated 

in MA 310 CMR 7.19 and approved into 

the MA SIP on October 15, 2020 (85 FR 

65236). The permits also require the 

performance of the unit and its controls 

to be verified. Therefore, Massachusetts 

concluded that it has met this Ask-1 

strategy and represented that it will 

continue to do so for new units that 

begin operation during the second 

planning period based on the rules now 

in effect. 

MANE–VU Ask 2 consists of a request 

that states ‘‘Emission sources modeled 

by MANE–VU that have the potential 

for 3.0 Mm-1 or greater visibility 

impacts at any MANE–VU Class I area, 

as identified by MANE–VU contribution 

analyses . . . perform a four-factor 

analysis for reasonable installation or 

upgrade to emission controls.’’ 

Massachusetts explained that, after 

examining the visibility impact 

modeling results (described in Section 5 

of Massachusetts’ submittal), MANE– 

VU concluded that a 3 Mm-1 cutoff 

captured the group of sources 

contributing the largest percentage of 

visibility impairing pollutants to Class I 

areas and that the determination of 

reasonability for controls on each unit 

was left to the individual states to allow 

for unit-specific consideration of the 

four factors. 

MANE–VU’s analysis identified 2 

units in Massachusetts with potential 

impacts of 3.0 Mm-1 or greater based on 

2015 emissions: Brayton Point 4 and 

Canal Station 1. Brayton Point was a 

coal-fired EGU facility (ORISPL 01619; 

MassDEP AQID 1200061). 

Massachusetts notes that all units at 

Brayton Point ceased operation in 2017 

and the permits were revoked on 

December 6, 2017. Canal Station 

(ORISPL 1599; MassDEP AQID 1200054) 

operates two steam electric generating 

units. Unit 1 is a Babcock & Wilcox 

boiler that fires No. 6 fuel oil, with a 

permitted maximum sulfur content of 

0.5 percent by weight (wt%) as the sole 

operational fuel, with No. 2 fuel oil as 

a startup/ignition fuel. Unit 1 has an 

approximate maximum heat input rate 

of 5,083 million British thermal units 

per hour (MMBtu/hr) and a generating 

capacity of approximately 560 (net) 

megawatts (MW). Unit 1 is equipped 

with low-NOX burners, overfire air 

ports, flue gas recirculation (FGR), and 

Selective Catalytic Reduction (SCR) for 

the control of NOX emissions. PM 

emissions are controlled by an 

Electrostatic Precipitator (ESP). In 

recent years, Unit 1 has operated with 

a capacity factor well below 10% 

The emission controls installed on 

Unit 1 are necessary to achieve 

compliance with the applicable 

emission limits under 310 CMR 7.29 

and Air Plan Approvals issued pursuant 

to 310 CMR 7.02. The governing NOX, 


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55See Appendix 31, ‘‘Four Factor Analysis Canal 

Unit 1, Canal Generating Station, Sandwich, MA 

. . .’’ 

56See MassDEP letter to EPA ‘‘Subject: Regional 

Haze SIP Revision for Massachusetts—supplement’’ 

and its attachment MassDEP letter to Canal 

Generating LLC, Air Quality Plan Approval. 

SO2, and PM emission limits for Unit 1 

are summarized in Table 6–1 of the MA 

SIP submission. 

The NOX and PM emission limits are 

readily met through the use of the 

installed emission controls. The sulfur 

content of No. 6 oil is limited to 0.5 

wt% in accordance with 310 CMR 7.05 

but the facility purchases 0.3 wt% 

sulfur No. 6 to meet the 6.0 lbs/MW-hr 

monthly, 3.0 lbs/MWhr rolling 12- 

month SO2 limit applicable under 310 

CMR 7.29. 

Table 6–2 in the State’s submittal 

shows Canal Unit 1’s actual emissions 

in 2015 along with much lower 

emissions MANE–VU projected for 2028 

and lower still for 2028 emissions under 

Ask 2. 

Massachusetts requested and received 

a four-factor analysis from the owner of 

the facility.55 Based on that analysis, 

Massachusetts concluded that visibility 

impairing pollutants from Canal Unit 1 

are currently well controlled with lowNOX burners, overfire air ports, flue gas 

recirculation (FGR), Selective Catalytic 

Reduction (SCR) and an Electrostatic 

Precipitator (ESP). In addition to these 

existing controls, however, Canal 

committed to purchase only 0.3 wt% 

No. 6 fuel oil, following the depletion of 

the current fuel inventory, which has at 

times contained No. 6 fuel oil with a 

sulfur content greater than 0.3 wt%. 

EPA expects that this commitment will 

further reduce its SO2 emissions. As a 

result, Massachusetts requested and 

received from the owner of Canal Unit 

1 an application to modify its plan 

approval to require use of 0.3% sulfur 

content oil. Massachusetts approved the 

application and submitted the Plan 

approval to EPA as a supplement to the 

Massachusetts Regional Haze SIP 

Revision in a letter dated June 15, 

2022.56 Massachusetts further notes 

that, if Canal Unit 1 should operate 

above 10% capacity factor in the future, 

existing SIP-approved NOX RACT 

regulations (310 CMR 7.19) will further 

limit the NOX emissions. Massachusetts 

states that it will evaluate any changes 

in the operation of Canal Unit 1 in 

future regional haze planning and 

reporting. 

MANE–VU Ask 3 is: ‘‘Each MANE– 

VU State that has not yet fully adopted 

an ultra-low sulfur fuel oil standard as 

requested by MANE–VU in 2007— 

pursue this standard as expeditiously as 

possible and before 2028, depending on 

supply availability, where the standards 

are as follows: a. distillate oil to 

0.0015% sulfur by weight (15 ppm); b. 

#4 residual oil within a range of 0.25 to 

0.5% sulfur by weight; and c. #6 

residual oil within a range of 0.3 to 

0.5% sulfur by weight.’’ MANE–VU 

included the low sulfur fuel measure in 

the 2017 Ask because some states had 

not implemented it yet and the 

justifications for it determined in the 

first implementation period remained 

valid. As described in Section 3 of the 

Massachusetts SIP submittal, MassDEP 

met the requirements of Ask 3 during 

the first implementation period by 

generally adopting low-sulfur oil 

regulations in the first planning period. 

Massachusetts adopted 310 CMR 7.05, 

‘‘Fuels All Districts’’ which was 

approved by EPA into the 

Massachusetts SIP on September 19, 

2013 (78 FR 57487). 

MANE–VU Ask 4 is: ‘‘EGUs and other 

large point emission sources larger than 

250 MMBTU per hour heat input that 

have switched operations to lower 

emitting fuels—pursue updating 

permits, enforceable agreements, and/or 

rules to lock-in lower emission rates for 

SO2, NOX and PM. The permit, 

enforcement agreement, and/or rule can 

allow for suspension of the lower 

emission rate during natural gas 

curtailment.’’ Massachusetts explains 

that MANE–VU chose this measure 

because the lower cost of natural gas 

had made switching to natural gas 

reasonable for many facilities resulting 

in significant visibility improvements. 

Also, the FLMs recommended during 

consultation that MANE–VU secure 

these visibility gains. 

The threshold of 250 MMBTU per 

hour heat input was based on prior 

BART analysis. Because there are no 

longer any large coal burning units in 

Massachusetts, this Ask pertains only to 

oil burning units. Massachusetts 

identified no dual/multi-fuel units 

larger than 250 MMBTU/hr that had 

made a physical change to switch to a 

cleaner fuel. All such dual/multi-fuel 

units are either continuing to burn a mix 

of fuels or are choosing to maintain their 

ability to do so in the future. 

MANE–VU Ask 5 is: ‘‘Where emission 

rules have not been adopted, control 

NOX emissions for peaking combustion 

turbines that have the potential to 

operate on high electric demand days 

by: a. Striving to meet NOX emissions 

standard of no greater than 25 ppm at 

15% O2 for natural gas and 42 ppm at 

15% O2 for fuel oil but at a minimum 

meet NOX emissions standard of no 

greater than 42 ppm at 15% O2 for 

natural gas and 96 ppm at 15% O2 for 

fuel oil; b. Performing a four-factor 

analysis for reasonable installation or 

upgrade to emission controls; or c. 

Obtaining equivalent alternative 

emission reductions on high electric 

demand days.’’ 

Massachusetts explains that ‘‘High 

electric demand days are days when 

higher than usual electrical demands 

bring additional generation units online, 

many of which are infrequently 

operated and may have significantly 

higher emission rates than the rest of the 

generation fleet. Peaking combustion 

turbine is defined for the purposes of 

this ‘Ask’ as a turbine capable of 

generating 15 megawatts or more, that 

commenced operation prior to May 1, 

2007, is used to generate electricity all 

or part of which is delivered to the 

electric power distribution grid for 

commercial sale and that operated less 

than or equal to an average of 1752 

hours (or 20%) per year during 2014 to 

2016; MANE–VU found a correlation 

between high electric demand days 

(HEDDs) and the 20% most impaired 

days at Class I areas. Because smaller 

turbines have the ability to respond to 

peak electrical demand and some of 

these units are not well controlled by 

existing rules (i.e., have a higher 

emission rate per unit of energy), 

MANE–VU found that controlling these 

units (or providing equivalent 

reductions on HEDDs) was a reasonable 

strategy for reducing NOX emissions on 

the most impaired days.’’ 

Massachusetts identified 25 turbines 

rated at 15 MW or higher that were 

operational prior to 2007 that sold 

electricity to the grid and that operated 

less than an average of 1752 hours per 

year during 2014–2016. These 25 

turbines are listed in Table 6–3 along 

with their current emission limits. On 

March 9, 2018, MassDEP revised 310 

CMR 7.19 Reasonably Available Control 

Technology (RACT) for Sources of 

Oxides of Nitrogen (NOX) to establish 

more stringent emissions limits for 

stationary turbines at major sources. 

With these revisions Massachusetts 

RACT now meets Ask 5 ‘‘striving’’ 

limits for combined cycle turbines and 

‘‘minimum’’ limits for simple cycle 

turbines. However, the 2018 RACT rule 

also included an exemption for units 

with a capacity factor less than 10% 

based on the most recent 3-year average, 

as codified in 310 CMR 7.19(1)(d). 

Almost all the turbines subject to Ask 

5 fall below the 10% capacity factor 

because they all run very infrequently. 

If in the future, they exceed the 10% 

capacity factor limit then they will be 

subject to the SIP-approved RACT limits 

of 310 CMR 7.19 and will therefore meet 

Ask 5 (except for Woodland 10 and 

Doreen 10 which are not located at 


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57See Massachusetts Regional Haze SIP 

Submission at 83–94. 

58See Appendix 2 ‘‘Contributions to Regional 

Haze in the Northeast and Mid-Atlantic United 

States: Mid-Atlantic/Northeast Visibility Union 

(MANE–VU) Contribution Assessment. NESCAUM. 

August 2006.’’ 

59See Appendix 22 ‘‘Mid-Atlantic/Northeast U.S. 

Visibility Data, 2004–2019 (2nd RH SIP Metrics). 

MANE–VU (prepared by Maine Department of 

Environmental Protection). January 21, 2021 

revision.’’ 60 Id. 

facilities that are major sources and are 

therefore not subject to 310 CMR 7.19). 

The turbines that are exempt from the 

2018 RACT limits are still subject to 

MassDEP’s 1995 RACT limits, however. 

Table 6–4 in MassDEP’s submission 

compares the 1995 and 2018 RACT 

limits to Ask 5, showing that the 1995 

RACT limits meet the Ask 5 minimum 

limits for combined cycle turbines, 

although not for simple cycle turbines. 

MassDEP explains that, as a result, 14 of 

the 25 turbines therefore meet the Ask 

5 limits through either 1995 RACT 

limits for combined cycle turbines or 

through BACT permit limits. For the 

remaining 11 turbines that do not meet 

the Ask 5 limits, Massachusetts has 

chosen to address the Ask by 

demonstrating emission reductions from 

Brayton Point Station (Units 1, 2, and 3) 

and Solutia that more than offset the 

emissions from these 11 turbines,57 as 

allowed under the Ask. 

MANE–VU Ask 6 is: ‘‘Each State 

should consider and report in their SIP 

measures or programs to: (a) decrease 

energy demand through the use of 

energy efficiency, and (b) increase the 

use within their state of Combined Heat 

and Power (CHP) and other clean 

Distributed Generation technologies 

including fuel cells, wind, and solar.’’ 

Massachusetts has taken numerous 

actions to decrease energy demand 

through energy efficiency and has been 

named the most energy efficient state in 

the nation by the American Council for 

an Energy-Efficient Economy (ACEEE) 

for nine consecutive years. 

Massachusetts ranks second in electric 

efficiency program spending per capita 

(at over four times the national average). 

Massachusetts energy efficiency efforts 

will continue through the second 

regional haze implementation period 

and will achieve emissions reductions 

beyond those required in the MANE–VU 

Statement. Key features of the 

Massachusetts energy efficiency strategy 

and efforts to expand non-polluting 

sources of energy and include energy 

efficiency, clean energy, solar carve-out, 

Solar Massachusetts Renewable Target 

(SMART) Program, Clean Energy 

Standard (310 CMR 7.75), Regional 

Greenhouse Gas Initiative (RGGI), 

combined heat and power (CHP), clean 

peak energy standard (CPS), offshore 

wind power, and hydroelectric power. 

Though not part of the SIP, these 

programs and initiatives have already 

achieved substantial emissions 

reductions and will continue to 

contribute to visibility improvements in 

Class I areas through 2028 and beyond. 

b. The EPA’s Evaluation of 

Massachusetts’ Response to the Six 

MANE–VU Asks and Compliance with 

§ 51.308(f)(2)(i) 

The EPA is proposing to find that 

Massachusetts has satisfied the 

requirements of § 51.308(f)(2)(i) related 

to evaluating sources and determining 

the emission reduction measures that 

are necessary to make reasonable 

progress by considering the four 

statutory factors. We are proposing to 

find that Massachusetts has satisfied the 

four-factor analysis requirement through 

its analysis and actions to address 

MANE–VU Asks 2 and 3. We also 

propose to find that Massachusetts 

reasonably concluded that it satisfied all 

six Asks. 

As explained above, Massachusetts 

relied on MANE–VU’s technical 

analyses and framework (i.e., the Asks) 

to select sources and form the basis of 

its long-term strategy. MANE–VU 

conducted an inventory analysis to 

identify the source sectors that 

produced the greatest amount of SO2

and NOX emissions in 2011; inventory 

data were also projected to 2018. Based 

on this analysis, MANE–VU identified 

the top-emitting sectors for each of the 

two pollutants, which for SO2 include 

coal-fired EGUs, industrial boilers, oilfired EGUs, and oil-fired area sources 

including residential, commercial, and 

industrial sources. Major-emitting 

sources of NOX include on-road 

vehicles, non-road vehicles, and 

EGUs.58 The RPO’s documentation 

explains that ‘‘[EGUs] emitting SO2 and 

NOX and industrial point sources 

emitting SO2 were found to be sectors 

with high emissions that warranted 

further scrutiny. Mobile sources were 

not considered in this analysis because 

any ask concerning mobile sources 

would be made to EPA and not during 

the intra-RPO and inter-RPO 

consultation process among the states 

and tribes.’’ 59 EPA proposes to find that 

Massachusetts reasonably evaluated the 

two pollutants—SO2 and NOX—that 

currently drive visibility impairment 

within the MANE–VU region and that it 

adequately explained and supported its 

decision to focus on these two 

pollutants through its reliance on the 

MANE–VU technical analyses cited in 

its submission. 

Section 51.308(f)(2)(i) requires states 

to evaluate and determine the emission 

reduction measures that are necessary to 

make reasonable progress by applying 

the four statutory factors to sources in 

a control analysis. As explained 

previously, the MANE–VU Asks are a 

mix of measures for sectors and groups 

of sources identified as reasonable for 

states to address in their regional haze 

plans. Several of the Asks include 

analyses of emissions controls, and 

Massachusetts identifies numerous 

existing controls that are in the SIP and 

are included in the long-term strategy. 

Additionally, Ask 2 (requesting fourfactor analyses be conducted) and Ask 

3 (requesting adoption of low-sulfur fuel 

oil) specifically demonstrate 

Massachusetts’ consideration of the 

statutory factors and together allow the 

EPA to determine that Massachusetts’ 

SIP is sufficient to satisfy (f)(2)(i). For 

example, Massachusetts provided 

information on the four statutory factors 

for the identified source that continues 

to operate—an oil-fired EGU and 

included new fuel sulfur limits for that 

source in the SIP. See ‘‘Four Factor 

Analysis Canal Unit 1, Canal Generating 

Station, Sandwich, MA’’ in Appendix 

31. While MANE–VU formulated the 

Asks to be ‘‘reasonable emission 

reduction strategies’’ to control 

emissions of visibility impairing 

pollutants,60 EPA believes that Asks 2 

and 3, in particular, engage with the 

requirement that states determine the 

emission reduction measures that are 

necessary to make reasonable progress 

through consideration of the four 

factors. As laid out in further detail 

below, the EPA is proposing to find that 

MANE–VU’s four-factor analysis 

conducted to support the emission 

reduction measures in Ask 3 (ultra-low 

sulfur fuel oil Ask), in conjunction with 

Massachusetts’ supplemental analysis 

and explanation of how it has complied 

with Ask 2 (perform four-factor 

analysis) satisfy the requirement of 

§ 51.308(f)(2)(i). The emission reduction 

measures that are necessary to make 

reasonable progress must be included in 

the long-term strategy, i.e., in 

Massachusetts’ SIP. 40 CFR 51.308(f)(2). 

Massachusetts asserted that it satisfies 

Ask 1 because its SIP-approved 

regulations applicable to EGU boilers 

include year-round emission limits and 

because it already requires that controls 

be run whenever technically feasible. 

Air Plan Approvals that MassDEP has 

issued for these units set short-term 

NOX emissions limits in lbs/hr or 


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61See Appendix 20 ‘‘MANE–VU Regional Haze 

Consultation Report and Consultation 

Documentation—Final.’’ 

62See Appendix 37, MassDEP letter from Thomas 

Cushing, Chief, Permit Section, Bureau of Air & 

Waste to Robert Vasconcelos, Director, Brayton 

Point Energy, LLC. December 6, 2017. 

63See Appendix 31, ‘‘Four Factor Analysis Canal 

Unit 1, Canal Generating Station, Sandwich, MA 

. . .’’ 

64See MassDEP letter to EPA ‘‘Subject: Regional 

Haze SIP Revision for Massachusetts—supplement’’ 

and its attachment MassDEP letter to Canal 

Generating LLC, Air Quality Plan Approval. 

concentration. EPA thus proposes to 

find that Massachusetts reasonably 

concluded that it has satisfied Ask 1. 

Ask 2 addresses the sources MANE– 

VU determined have the potential for 

larger than, or equal to, 3.0 Mm¥1

visibility impact at any MANE–VU 

Class I area; the Ask requests MANE– 

VU states to conduct four-factor 

analyses for the specified sources within 

their borders. This Ask explicitly 

engages with the statutory and 

regulatory requirement to determine 

reasonable progress based on the four 

factors; MANE–VU considered it 

‘‘reasonable to have the greatest 

contributors to visibility impairment 

conduct a four-factor analysis that 

would determine whether emission 

control measures should be pursued and 

what would be reasonable for each 

source.’’ 61

As an initial matter, EPA does not 

generally agree that 3.0 Mm¥1 visibility 

impact is a reasonable threshold for 

source selection. The RHR recognizes 

that, due to the nature of regional haze 

visibility impairment, numerous and 

sometimes relatively small sources may 

need to be selected and evaluated for 

control measures in order to make 

reasonable progress. See 2021 

Clarifications Memo at 4. As explained 

in the 2021 Clarifications Memo, while 

states have discretion to choose any 

source selection threshold that is 

reasonable, ‘‘[a] state that relies on a 

visibility (or proxy for visibility impact) 

threshold to select sources for fourfactor analysis should set the threshold 

at a level that captures a meaningful 

portion of the state’s total contribution 

to visibility impairment to Class I 

areas.’’ 2021 Clarifications Memo at 3. 

In this case, the 3.0 Mm¥1 threshold 

identified only two sources in 

Massachusetts (and only 22 across the 

entire MANE–VU region), indicating 

that it may be unreasonably high. 

MANE–VU identified two units in 

Massachusetts with potential impacts of 

3.0 Mm-1 or greater based on 2015 

emissions: Brayton Point Unit 4 and 

Canal Station Unit 1. Brayton Point was 

a coal-fired EGU facility (ORISPL 01619; 

MassDEP AQID 1200061). All four of 

the coal-fired units at Brayton Point, 

including Unit 4, ceased operation in 

2017 and the permits were revoked on 

December 6, 2017.62

Canal Station (ORISPL 1599; 

MassDEP AQID 1200054) operates two 

steam electric generating units. Unit 1 is 

a Babcock & Wilcox boiler that fires No. 

6 fuel oil, with a permitted maximum 

sulfur content of 0.5 percent by weight 

(wt%) as the sole operational fuel, with 

No. 2 fuel oil as a startup/ignition fuel. 

Unit 1 has an approximate maximum 

heat input rate of 5,083 million British 

thermal units per hour (MMBtu/hr) and 

a generating capacity of approximately 

560 (net) megawatts (MW). Unit 1 is 

equipped with low-NOX burners, 

overfire air ports, flue gas recirculation 

(FGR), and Selective Catalytic 

Reduction (SCR) for the control of NOX

emissions. PM emissions are controlled 

by an Electrostatic Precipitator (ESP). 

The emission controls installed on Unit 

1 are necessary to achieve compliance 

with the applicable emission limits 

under 310 CMR 7.29 and Air Plan 

Approvals issued pursuant to 310 CMR 

7.02. The governing NOX, SO2, and PM 

emission limits for Unit 1 are 

summarized in Table 6–1 of the 

Massachusetts SIP submittal. 

Pursuant to Ask 2, MassDEP 

requested a four-factor analysis from the 

owner of Canal Unit 1, which the owner 

submitted on September 19, 2020.63

With respect to NOX emissions, the 

analysis concludes that Canal Unit 1’s 

existing controls (low NOX burners, 

overfire air ports, FGR, and SCR) are the 

most stringent available and that there 

are no other add-on controls 

commercially available to reduce NOX

emissions from Canal Unit 1. The 

analysis explains that Canal Unit 1 has 

operated well below 10% capacity 

factor in recent years, is subject to NOX

emission limits pursuant to 310 CMR 

7.29 when operating at this level and is 

not expected to increase its capacity 

factor in the future. If Canal Unit 1 did 

exceed 10% capacity factor, the higher 

number of hours would result in better 

performance of the SCR and, thereby, 

reduce NOX emissions rates by at least 

50% below the current permitted NOX

limits. Furthermore, if Canal Unit 1 

exceeded 10% capacity factor, it would 

automatically become subject to the 

lower NOX limit in MassDEP’s NOX

RACT regulations (310 CMR 7.19). 

Infrequent operation limits the 

effectiveness of the existing controls, 

however. At its current and expected 

low capacity factor, meeting NOX

emission limits below the existing 310 

CMR 7.29 limits would be unreasonable 

due to emissions that occur during 

startup prior to operation of the SCR. 

The analysis concludes that no further 

NOX control measures at Canal Unit 1 

are necessary to make reasonable 

progress. 

With respect to SO2 emissions, the 

four-factor analysis concludes that 

conversion to natural gas is not 

technically feasible due to supply 

limitations but that use of 0.3% sulfur 

No.6 fuel oil (rather than the 0.5% 

sulfur allowed under Massachusetts’ 

low sulfur fuel regulations at 310 CMR 

7.05) is technically feasible and reduces 

SO2 emissions by 40% at a cost of 

$10,000 per ton of SO2 reduced. While 

the analysis concludes that the cost of 

using 0.3 wt% sulfur No. 6 oil would 

not be considered reasonable, the owner 

nonetheless committed to purchasing 

0.3 wt% No. 6 fuel oil following the 

depletion of the current fuel inventory 

because the MANEVU Regional Haze 

Consultation Report identifies sulfates 

from SO2 emissions as the primary 

driver behind visibility impairment in 

the region. See June 15, 2022, MassDEP 

Regional Haze SIP Revision for 

Massachusetts Supplement.64

The four-factor analysis also evaluates 

the use of ultra-low sulfur diesel (ULSD) 

and retrofitting with a spray dry 

absorber for SO2 control and concludes 

that, while technically feasible, the costs 

of compliance in each case (beginning at 

$21,000 per ton of SO2 reduced) mean 

that neither measure is necessary for 

reasonable progress. The analysis also 

evaluated particulate matter emissions 

and concludes that they are well 

controlled with an electrostatic 

precipitator (ESP) and burning 0.3 wt% 

sulfur fuel. While adding a fabric filter 

and using ULSD is feasible, the costs are 

$50,000 and $170,000 per ton of SO2

reduced, respectively and, the ESP 

would reduce the efficiency of the unit 

by 0.5% and generate 52 tons of waste 

per year. 

Based on Canal’s commitment to use 

0.3% sulfur content fuel oil, MassDEP 

requested that the Permittee submit a 

permit application to require its use. 

Subsequently, MassDEP modified 

Canal’s Plan Approval to provide that 

the sulfur content of No. 6 fuel oil 

purchased for Unit 1 shall not exceed 

0.3% by weight. MassDEP has requested 

that EPA approve it into the SIP, which 

EPA proposes to do in today’s action. 

The EPA proposes to find that 

Massachusetts reasonably determined it 

has satisfied Ask 2. As explained above, 

we do not generally agree that a 3.0 

Mm¥1 threshold for selecting sources 

for four-factor analysis results in a set of 

sources to evaluate that will result in 


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65Massachusetts Chapter 353 of the Acts of 1974. 

potential and meaningful reduction of 

the state’s contribution to visibility 

impairment. MANE–VU’s threshold 

identified two sources, only one of 

which continues to operate and combust 

the same fuel. However, in this 

particular instance we propose to find 

that Massachusetts’ additional 

information and explanation indicate 

that the state has conducted a 

reasonable examination of its sources, 

reasonably concluded that the fourfactor analysis for its remaining 

impacting source is satisfactory, and 

accurately concluded the additional SO2

controls further limiting fuel oil sulfur 

content are reasonable emission 

reductions. EPA is basing this proposed 

finding on the State’s examination of its 

largest operating EGU and ICI sources, 

at the time of SIP submission, and on 

the emissions from and controls that 

apply to those sources, as well as on 

Massachusetts’ existing SIP-approved 

NOX and SO2 rules that effectively 

control emissions from the largest 

contributing stationary-source sectors. 

Ask 3, which addresses the sulfur 

content of heating oil used in MANE– 

VU states, is based on a four-factor 

analysis for the heating oil sulfur 

reduction regulations contained in that 

Ask; specifically, for the control strategy 

of reducing the sulfur content of 

distillate oil to 15 ppm. As described in 

Section 3 of the Massachusetts SIP 

submittal, MassDEP met the 

requirements of Ask 3 during the first 

implementation period by generally 

adopting low-sulfur oil regulations in 

the first planning period. Massachusetts 

adopted 310 CMR 7.05, ‘‘Fuels All 

Districts.’’ The regulation limited the 

Statewide sulfur content of distillate oil 

to 500 parts per million (ppm) from July 

1, 2014, through June 30, 2018, and then 

to 15 ppm starting July 1, 2018. The 

regulation also sets the sulfur in fuel 

limit for No. 6 residual oil, starting July 

1, 2018, at 0.5% by weight Statewide, 

except for the Berkshire Air Pollution 

Control District (APCD), which 

encompasses the Towns and Cities in 

Berkshire County, the westernmost 

county in the Commonwealth. The 

Berkshire APCD has a 1974 legislative 

exemption allowing sources in this 

district to burn up to 2.2% sulfur 

residual oil.65 Therefore, the regulation 

does not explicitly require lower sulfur 

residual oil in the Berkshire APCD due 

to the existing law. A legislative change 

would be needed for MassDEP to apply 

the lower sulfur residual oil limits for 

this district. Despite the existing 

legislative exemption, however, 

MassDEP expects that the majority of 

residual oil burned in the Berkshire 

APCD will have a reduced sulfur 

content because the suppliers in 

Massachusetts and the surrounding 

states will need to supply lower sulfur 

residual oil for sale in those other 

APCDs and states. See also 77 FR 30932. 

The EPA proposes to find that 

Massachusetts reasonably relied on 

MANE–VU’s four-factor analysis for a 

low-sulfur fuel oil regulation, which 

engaged with each of the statutory 

factors and explained how the 

information supported a conclusion that 

a 15 ppm-sulfur fuel oil standard for 

fuel oils is reasonable. Massachusetts’ 

SIP-approved ultra-low sulfur fuel oil 

rule is consistent with Ask 3’s sulfur 

content standards for the three types of 

fuel oils (distillate oil, #4 residual oil, 

#6 residual oil). EPA therefore proposes 

to find that Massachusetts reasonably 

determined that it has satisfied Ask 3. 

Massachusetts concluded that no 

additional updates were needed to meet 

Ask 4, which requests that MANE–VU 

states pursue updating permits, 

enforceable agreements, and/or rules to 

lock-in lower emission rates for sources 

larger than 250 MMBtu per hour that 

have switched to lower emitting fuels. 

As explained above, Massachusetts has 

asserted that there are no longer any 

large coal burning units in 

Massachusetts, meaning that this Ask 

pertains only to oil burning units. MA 

identified no dual/multi-fuel units 

larger than 250 MMBTU/hr that had 

made a physical change to switch to a 

cleaner fuel. All such dual/multi-fuel 

units are either continuing to burn a mix 

of fuels or are choosing to maintain their 

ability to do so in the future. In 

addition, modified units in 

Massachusetts are required to amend 

their permits through the New Source 

Review (NSR) process if they plan to 

switch back to coal or a fuel that will 

increase emissions. A change in fuel, 

unless already allowed in the permit, 

would be a modification. 

Thus, given the permitting and 

regulatory requirements outlined above, 

including the fact that sources that have 

switched fuel are required to revise their 

permits to reflect the change, that state 

rules make any proposed reversion 

difficult by requiring permitting and 

other control analyses, including NSR, 

the EPA proposes to find that 

Massachusetts reasonably determined it 

has satisfied Ask 4. 

Ask 5 addresses NOX emissions from 

peaking combustion turbines that have 

the potential to operate on high electric 

demand days. Massachusetts explains 

that it has SIP-approved regulations to 

control peaking combustion turbines 

that have the potential to operate on 

high electric demand days. The Ask 

requests states to ‘‘strive’’ for NOX

emission standards of no greater than 25 

ppm for natural gas and 42 ppm for fuel 

oil, or at a minimum, NOX emissions 

standards of no greater than 42 ppm for 

natural gas and 96 ppm at for fuel oil. 

Massachusetts RACT requirements 

approved into the MA SIP on October 

15, 2020 (85 FR 65236) meet Ask 5 

‘‘striving’’ limits for combined cycle 

turbines and ‘‘minimum’’ limits for 

simple cycle turbines. However, the 

2018 RACT rule also included an 

exemption for units with a capacity 

factor less than 10% based on the most 

recent 3-year average. As shown in 

Table 6–3 of the Massachusetts SIP 

submittal, most of the turbines subject 

to Ask 5 fall below the 10% capacity 

factor because they all run very 

infrequently. If in the future they exceed 

the 10% capacity factor limit, then they 

will be subject to the RACT limits of 310 

CMR 7.19 and will therefore meet Ask 

5 (except for Woodland 10 and Doreen 

10 which are not located at facilities 

that are major sources and are therefore 

not subject to 310 CMR 7.19). The 

turbines that are exempt from the 2018 

RACT limits are still subject to 

MassDEP’s 1995 RACT limits. For 

combined cycle turbines, the 1995 

RACT limits meet Ask 5 minimum 

required limits for oil and gas, but the 

simple cycle limits are slightly higher at 

100 ppm compared to the Ask 5 

minimum of 96 ppm. 

Ask 5 included an option to achieve 

equivalent alternative emission 

reductions for those combustion 

turbines whose limits do not match the 

‘‘minimum’’ limits in the Ask. The 

retirement of Brayton Point 1–2–3 and 

repowering of Solutia Boiler 11 each 

provide alternative SO2 or NOX

emission reductions, respectively, on 

HEDDs that are far larger than any NOX

reductions possible from the turbines 

that do not already meet Ask 5 (156 and 

128 tons/year vs. 25 tons/year). 

Furthermore, the annual SO2 emission 

reductions from Brayton Point 1–2–3 

(785 tons/year) and Solutia Boiler 11 

(847 tons/year combined SO2 and NOX) 

are each sufficiently large to offset all 

the annual turbine NOX emissions (51 

tons per year). 

Therefore, the permanent retirement 

of Brayton 1–2–3 and repowering of 

Solutia Boiler 11 each satisfies the Ask 

for the remaining 11 turbines not 

covered by the most recent MassDEP 

RACT rule. Because the Solutia Boiler 

11 repowering and Brayton 1–2–3 

retirements offset over 100% of the 

emissions from the 11 turbines on 

HEDDs, they exceed the visibility 

improvement requirements of Ask 5. In 


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66See Appendix 20 ‘‘MANE–VU Regional Haze 

Consultation Report.’’ 

addition, because MassDEP has 

permitted new units (e.g., Footprint 1⁄2, 

Canal 3, and West Medway 4⁄5) that are 

much cleaner than the 11 turbines, these 

new units likely will displace some of 

the power generating capacity of the 

older turbines units and thereby further 

reduce HEDD emissions from the 

turbines that do not meet Ask 5. 

For the majority of combustion 

turbines identified in the Ask, the RACT 

levels adopted by Massachusetts comply 

with the minimum requested by this 

Ask. For those turbines that do not meet 

the minimum limits, MassDEP has 

identified alternative emission 

reductions obtained through the 

retirement of Brayton 1–2–3 and the 

repowering of Solution Boiler 11 that 

more than make up the difference. 

Therefore, EPA proposes to find that 

Massachusetts reasonably concluded 

that its existing regulations comply with 

Ask 5. 

Finally, with regard to Ask 6, 

Massachusetts has taken numerous 

actions to decrease energy demand 

through energy efficiency and has been 

named the most energy efficient state in 

the nation by the American Council for 

an Energy-Efficient Economy (ACEEE) 

for nine consecutive years. The EPA is 

proposing to find that Massachusetts 

has satisfied Ask 6’s request to consider 

and report in its SIP measures or 

programs related to energy efficiency, 

cogeneration, and other clean 

distributed generation technologies. 

In sum, the EPA is proposing to 

find—based on Massachusetts’ 

participation in the MANE–VU 

planning process, how it has addressed 

the Asks, and the EPA’s assessment of 

Massachusetts’ emissions and point 

sources—that Massachusetts has 

complied with the requirements of 

§ 51.308(f)(2)(i). Specifically, 

Massachusetts’s application of MANE– 

VU Asks 1 2, and 3 engages with the 

requirement that states evaluate and 

determine the emission reduction 

measures necessary to make reasonable 

progress by considering the four 

statutory factors. 

EPA is proposing to find the state’s 

approach meets the regulatory 

requirements for several reasons. 

Massachusetts reasonably evaluated and 

explained its decision to focus on SO2

and NOX to address visibility 

impairment within the MANE–VU 

region. Massachusetts also adequately 

supported that decision through 

reasonable reliance on the MANE–VU 

technical analyses cited in its 

submission. In addition, Massachusetts 

selected the sources with the greatest 

modeled impacts on visibility and also 

adequately responded to comments to 

consider sources identified by the FLMs 

through the consultation process. 

Massachusetts’s submittal also includes 

four-factor analyses and demonstrates 

that the sources of SO2 and NOX within 

the state that would be expected to 

contribute to visibility impairment have 

small emissions of NOX and SO2, are 

subject to stringent SIP-approved 

emission control measures, or both. In 

addition, Massachusetts’s SIP-approved 

sulfur in fuel rule sets stringent limits 

for sulfur content and SO2 emissions for 

fuels. The Massachusetts SIP submittal 

also includes a plan approval for Canal 

Generating Station, requiring fuel oil 

purchased for EU1 be restricted to 0.3% 

sulfur content limit. 

EPA proposes to find that 

Massachusetts’s SIP submittal satisfies 

the requirements that states determine 

the emission reduction measures that 

are necessary to make reasonable 

progress by considering the four factors, 

and that their long-term strategies 

include the enforceable emission 

limitations, compliance schedules, and 

other measures necessary to make 

reasonable progress. 

c. Additional Long-Term Strategy 

Requirements 

The consultation requirements of 

§ 51.308(f)(2)(ii) provide that states must 

consult with other states that are 

reasonably anticipated to contribute to 

visibility impairment in a Class I area to 

develop coordinated emission 

management strategies containing the 

emission reductions measures that are 

necessary to make reasonable progress. 

Section 51.308(f)(2)(ii)(A) and (B) 

require states to consider the emission 

reduction measures identified by other 

states as necessary for reasonable 

progress and to include agreed upon 

measures in their SIPs, respectively. 

Section 51.308(f)(2)(ii)(C) speaks to 

what happens if states cannot agree on 

what measures are necessary to make 

reasonable progress. 

Massachusetts participated in and 

provided documentation of the MANE– 

VU intra- and inter-RPO consultation 

processes, which included consulting 

with both MANE–VU and non-MANE– 

VU states about emissions from 

Massachusetts reasonably anticipated to 

contribute to visibility impairment in 

Class I areas within the MANE–VU area 

and in adjacent areas. The consultations 

addressed developing coordinated 

emission management strategies 

containing the emission reductions 

necessary to make reasonable progress 

at the Class I areas. Massachusetts 

addressed the MANE–VU Asks by 

providing information on the measures 

it has in place that satisfy each Ask.66

While Massachusetts did not receive 

any requests from non-MANE–VU states 

to consider additional measures to 

address visibility impairment in Class I 

areas outside MANE–VU, MANE–VU 

documented disagreements that 

occurred during consultation. For 

instance, MANE–VU noted in its 

Consultation Report that upwind states 

expressed concern regarding the 

analyses the RPO utilized for the 

selection of states for the consultation. 

MANE–VU agreed that these tools, as all 

models, have their limitations, but 

nonetheless deemed them appropriate. 

Additionally, there were several 

comments regarding the choice of the 

2011 modeling base year. MANE–VU 

agreed that the choice of base year is 

critical to the outcome of the study. 

MANE–VU acknowledged that there 

were newer versions of the emission 

inventories and the need to use the best 

available inventory for each analysis. 

However, MANE–VU disagreed that the 

choice of these inventories was not 

appropriate for the analysis. 

Additionally, upwind states noted that 

they would not be able to address the 

MANE–VU Asks until they finalize their 

SIPs. MANE–VU believed the 

assumption of the implementation of 

the Asks from upwind states in its 2028 

control case modeling was reasonable, 

and Massachusetts included both the 

2028 base case and control case 

modeling results in its SIP, representing 

visibility conditions at Acadia National 

Park (Maine) assuming upwind states do 

not and do implement the Asks, 

respectively. 

In sum, Massachusetts participated in 

the MANE–VU intra- and inter-RPO 

consultation and included in its SIP 

submittal the measures identified and 

agreed to during those consultations, 

thereby satisfying § 51.308(f)(2)(ii)(A) 

and (B). Massachusetts satisfied 

§ 51.308(f)(2)(ii)(C) by participating in 

MANE–VU’s consultation process, 

which documented the disagreements 

between the upwind states and MANE– 

VU and explained MANE–VU’s 

reasoning on each of the disputed 

issues. Based on the entirety of MANE– 

VU’s intra- and inter-RPO consultation 

and MANE–VU’s and Massachusetts’ 

responses to comments on the SIP 

submission and various technical 

analyses therein, we propose to 

determine that Massachusetts has 

satisfied the consultation requirements 

of § 51.308(f)(2)(ii). 

The documentation requirement of 

§ 51.308(f)(2)(iii) provides that states 


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67See tables 6–13 of the MassDEP Regional Haze 

SIP—Final July 2021. 

may meet their obligations to document 

the technical bases on which they are 

relying to determine the emission 

reductions measures that are necessary 

to make reasonable progress through an 

RPO, as long as the process has been 

‘‘approved by all State participants.’’ As 

explained above, Massachusetts chose 

to rely on MANE–VU’s technical 

information, modeling, and analysis to 

support development of its long-term 

strategy. The MANE–VU technical 

analyses on which Massachusetts relied 

are listed in the state’s SIP submission 

and include source contribution 

assessments, information on each of the 

four factors and visibility modeling 

information for certain EGUs, and 

evaluations of emission reduction 

strategies for specific source categories. 

Massachusetts also provided 

supplemental information to further 

demonstrate the technical bases and 

emission information on which it relied 

on to determine the emission reductions 

measures that are necessary to make 

reasonable progress. Based on the 

documentation provided by the state, 

we propose to find Massachusetts 

satisfies the requirements of 

§ 51.308(f)(2)(iii). 

Section 51.308(f)(2)(iii) also requires 

that the emissions information 

considered to determine the measures 

that are necessary to make reasonable 

progress include information on 

emissions for the most recent year for 

which the state has submitted triennial 

emissions data to the EPA (or a more 

recent year), with a 12-month 

exemption period for newly submitted 

data. Massachusetts’ SIP submission 

included 2017 National Emissions 

Inventory (NEI) data for NOX, SO2, PM, 

VOCs and NH3 and 2017 Air Markets 

Program Data (AMPD) emissions for 

NOX and SO2. Based on Massachusetts’ 

consideration and analysis of the 2017 

and 2019 emission data in their SIP 

submittal, the EPA proposes to find that 

Massachusetts has satisfied the 

emissions information requirement in 

51.308(f)(2)(iii). 

We also propose to find that 

Massachusetts reasonably considered 

the five additional factors in 

§ 51.308(f)(2)(iv) in developing its longterm strategy. Pursuant to 

§ 51.308(f)(2)(iv)(A), Massachusetts 

noted that existing and ongoing state 

and federal emission control programs 

that contribute to emission reductions 

through 2028 would impact emissions 

of visibility impairing pollutants from 

point and nonpoint sources in the 

second implementation period. 

Massachusetts included in its SIP a 

comprehensive lists of control measures 

identifying the source category and 

corresponding Code of Massachusetts 

Regulations provisions.67

Massachusetts’ consideration of 

measures to mitigate the impacts of 

construction activities as required by 

§ 51.308(f)(2)(iv)(B) includes, in section 

6.6 of its SIP submission, measures that 

Massachusetts has implemented to 

mitigate the impacts from such 

activities. Massachusetts has 

implemented standards that reduce 

fugitive dust emissions from 

construction, rules to address exhaust 

emissions including rules to limit the 

idling of vehicles and equipment, rules 

to reduce allowable smoke from on-road 

diesel engines, and general conformity 

rules. 

Pursuant to § 51.308(f)(2)(iv)(C), 

source retirements and replacement 

schedules are addressed in section 6.7 

of Massachusetts’ submission. Source 

retirements and replacements were 

considered in developing the 2028 

emission projections, with on the books/ 

on the way retirements and 

replacements included in the 2028 

projections. The EGU point sources 

included in the inventories used in the 

MANE–VU contribution assessment and 

that were subsequently retired are 

described in Section 4 of the 

Massachusetts’ submission. 

In considering smoke management as 

required in 40 CFR 51.308(f)(2)(iv)(D), 

Massachusetts explained, in section 6.8 

of its submission, that it addresses 

smoke management through its air 

regulation at 310 CMR 7.07, which bans 

open burning in 22 urban municipalities 

and prohibits the use of open burning to 

clear commercial or institutional land 

for non-agricultural purposes. 

Prescribed burning is allowed upon 

specific permission from MassDEP. 

Massachusetts considers these efforts to 

be sufficient to protect visibility in the 

Class I areas affected by emission from 

Massachusetts source, including 

agricultural and forestry smoke. 

Massachusetts considered the 

anticipated net effect of projected 

changes in emissions as required by 

51.308(f)(2)(iv)(E) by discussing, in 

Section 6.9 of its submission, the 

photochemical modeling for the 2018– 

2028 period it conducted in 

collaboration with MANE–VU. The two 

modeling cases run were a 2028 base 

case, which considered only on-thebooks controls, and a 2028 control case 

that considered implementation of the 

MANE–VU Ask. The results of that 

modeling are shown as RPGs on the 

graphs in Section 2 and detailed in the 

presentation of RPGs in the MANE–VU 

visibility report. The 2028 inventory 

projections demonstrate a substantial 

reduction in emissions. The modeling 

shows that projected visibility at all 

potentially impacted Class I areas will 

remain well below the URP line in 2028 

for the most impaired days and that 

there will be no degradation in visibility 

for the least impaired days. 

Because Massachusetts has reasonably 

considered each of the five additional 

factors, the EPA proposes to find that 

Massachusetts has satisfied the 

requirements of 40 CFR 51.308(f)(2)(iv). 

F. Reasonable Progress Goals 

Section 51.308(f)(3) contains the 

requirements pertaining to RPGs for 

each Class I area. Because 

Massachusetts does not host a Class I 

area, it is not subject to either 

§ 51.308(f)(3)(i) or 51.308(f)(3)(ii)(A). 

Section 51.308(f)(3)(ii)(B) requires that, 

if a state contains sources that are 

reasonably anticipated to contribute to 

visibility impairment in a Class I area in 

another state and the RPG for the most 

impaired days in that Class I area is 

above the URP, the upwind state must 

provide the same demonstration. 

Table 2–1 of Massachusetts’ SIP 

submittal summarizes baseline visibility 

conditions (i.e., visibility conditions 

during the baseline period) for the most 

impaired and clearest days and the 2028 

RPG for the most impaired days for 

Class I areas in or adjacent to the 

MANE–VU Region, as well as 

information on natural visibility 

conditions, the rate of progress 

described by the URP in 2017 and 2028, 

and the modeled 2028 base case 

(representing visibility conditions in 

2028 with existing controls). These 

visibility conditions, as well as the 2028 

reasonable progress goal for the clearest 

days, are also included in Appendix 21 

of Massachusetts’ SIP submission. As 

noted in the submission, the RPGs for 

all of the Class I areas in or adjacent to 

the MANE–VU region are well below 

their respective URP glidepaths. 

Therefore, § 51.308(f)(3)(ii)(B) is not 

applicable to Massachusetts. 

G. Monitoring Strategy and Other 

Implementation Plan Requirements 

Section 51.308(f)(6) specifies that 

each comprehensive revision of a state’s 

regional haze SIP must contain or 

provide for certain elements, including 

monitoring strategies, emissions 

inventories, and any reporting, 

recordkeeping and other measures 

needed to assess and report on 

visibility. Since Massachusetts does not 

contain any Class I areas, it is not 

required to submit the monitoring 

strategy referenced in 51.308(f)(6), nor 


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68See Appendix 22 ‘‘Mid-Atlantic/Northeast U.S. 

Visibility Data, 2004–2019 (2nd RH SIP Metrics). 

MANE–VU (prepared by Maine Department of 

Environmental Protection). January 21, 2021 

revision.’’ 

69See appendix 21 ‘‘OTC MANE–VU 2011 Based 

Modeling Platform Support Document October 

2018—Final.’’ 

are the requirements in 51.308(f)(6)(i), 

(ii), and (iv) applicable. 

40 CFR 51.308(f)(6)(iii), however, 

applies to states with no Class I areas 

(such as Massachusetts) and requires 

them to include in their Regional Haze 

SIPs procedures by which monitoring 

data and other information are used in 

determining the contribution of 

emissions from within the state to 

visibility impairment at Class I areas in 

other states. Monitoring in 

Massachusetts that contributes data for 

assessing visibility is described in 

section 2.1 of the Massachusetts SIP 

submission. Visibility data analysis 

procedures are described in the MANE– 

VU visibility data report.68 Other 

procedures and data used for 

determining Massachusetts contribution 

to visibility impairment are described in 

section 5 of the Massachusetts SIP and 

the MANE–VU documents referenced. 

Two IMPROVE monitors in 

Massachusetts provide data to assess 

current visibility, track changes in 

visibility, and help determine the causes 

of visibility impairment in Class I areas 

in the region. 

Section 51.308(f)(6)(v) requires SIPs to 

provide for a statewide inventory of 

emissions of pollutants that are 

reasonably anticipated to cause or 

contribute to visibility impairment, 

including emissions for the most recent 

year for which data are available and 

estimates of future projected emissions. 

It also requires a commitment to update 

the inventory periodically. 

Massachusetts provides for emissions 

inventories and estimates for future 

projected emissions by participating in 

the MANE–VU RPO and complying 

with EPA’s Air Emissions Reporting 

Rule (AERR). In 40 CFR part 51, subpart 

A, the AERR requires states to submit 

updated emissions inventories for 

criteria pollutants to EPA’s Emissions 

Inventory System (EIS) every three 

years. The emission inventory data is 

used to develop the NEI, which 

provides for, among other things, a 

triennial state-wide inventory of 

pollutants that are reasonably 

anticipated to cause or contribute to 

visibility impairment. 

Section 4 of Massachusetts’ 

submission includes tables of NEI data. 

The source categories of the emissions 

inventories included are: (1) Point 

sources, (2) nonpoint sources, (3) nonroad mobile sources, and (4) on-road 

mobile sources. The point source 

category is further divided into AMPD 

point sources and non-AMPD point 

sources. Massachusetts included NEI 

emissions inventories for the following 

years: 2002 (one of the regional haze 

program baseline years), 2008, 2011, 

2014, and 2017; and for the following 

pollutants: SO2, NOX, PM10, PM2.5, 

VOCs, and NH3. 

Section 51.308(f)(6)(v) also requires 

states to include estimates of future 

projected emissions and include a 

commitment to update the inventory 

periodically. Massachusetts relied on 

the MANE–VU 2028 emissions 

projections for MANE–VU states. 

MANE–VU completed two 2028 

projected emissions modeling cases—a 

2028 base case that considers only onthe-books controls and a 2028 control 

case that considers implementation of 

the MANE–VU Asks.69

The EPA proposes to find that 

Massachusetts has met the requirements 

of 40 CFR 51.308(f)(6) as described 

above, including through its continued 

participation in the MANE–VU RPO and 

its on-going compliance with the AERR, 

and that no further elements are 

necessary at this time for Massachusetts 

to assess and report on visibility 

pursuant to 40 CFR 51.308(f)(6)(vi). 

Massachusetts’ SIP submittal also 

includes a commitment to update the 

statewide emissions inventory 

periodically. 

H. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

Section 51.308(f)(5) requires that 

periodic comprehensive revisions of 

states’ Regional Haze plans also address 

the progress report requirements of 40 

CFR 51.308(g)(1) through (5). The 

purpose of these requirements is to 

evaluate progress towards the applicable 

RPGs for any Class I area within the 

state and each Class I area outside the 

state that may be affected by emissions 

from within that state. Sections 

51.308(g)(1) and (2) apply to all states 

and require a description of the status 

of implementation of all measures 

included in a state’s first 

implementation period regional haze 

plan and a summary of the emission 

reductions achieved through 

implementation of those measures. 

Section 51.308(g)(3) applies only to 

states with Class I areas within their 

borders and requires such states to 

assess current visibility conditions, 

changes in visibility relative to baseline 

(2000–2004) visibility conditions, and 

changes in visibility conditions relative 

to the period addressed in the first 

implementation period progress report. 

Section 51.308(g)(4) applies to all states 

and requires an analysis tracking 

changes in emissions of pollutants 

contributing to visibility impairment 

from all sources and sectors since the 

period addressed by the first 

implementation period progress report. 

This provision further specifies the year 

or years through which the analysis 

must extend depending on the type of 

source and the platform through which 

its emission information is reported. 

Finally, § 51.308(g)(5), which also 

applies to all states, requires an 

assessment of any significant changes in 

anthropogenic emissions within or 

outside the state that have occurred 

since the period addressed by the first 

implementation period progress report, 

including whether such changes were 

anticipated and whether they have 

limited or impeded expected progress 

towards reducing emissions and 

improving visibility. 

Massachusetts’ submission describes 

the status of measures of the long-term 

strategy from the first implementation 

period. As a member of MANE–VU, 

Massachusetts considered the MANE– 

VU Asks and adopted corresponding 

measures into its long-term strategy for 

the first implementation period. The 

MANE–VU Asks were: (1) Timely 

implementation of Best Available 

Retrofit Technology (BART) 

requirements; (2) EGU controls 

including Controls at 167 Key Sources 

that most affect MANE–VU Class I areas; 

(3) Low sulfur fuel oil strategy; and (4) 

Continued evaluation of other control 

measures. Massachusetts met all the 

identified reasonable measures 

requested during the first 

implementation period. During the first 

planning period for regional haze, 

programs that were put in place focused 

on reducing SO2 emissions. The 

reductions achieved led to vast 

improvements in visibility at the 

MANE–VU Federal Class I Areas due to 

reduced sulfates formed from SO2

emissions. Massachusetts describes the 

control measures that help control the 

emissions of VOCs, NOX, PM and SO2

from a wide range of sources in Section 

3 of the Massachusetts’ SIP submission 

and identifies BART and Alternative to 

BART requirements in Table 3–1. The 

state included periodic emission data 

that demonstrate a decrease in VOCs, 

NOX, PM and SO2 emissions throughout 

the state. 

The EPA proposes to find that 

Massachusetts has met the requirements 

of 40 CFR 51.308(g)(1) and (2) because 

its SIP submission describes the 

measures included in the long-term 


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strategy from the first implementation 

period, as well as the status of their 

implementation and the emission 

reductions achieved through such 

implementation. 

Pursuant to § 51.308(g)(4), in Section 

4 of its submittal, Massachusetts 

provided a summary of emissions of 

NOX, SO2, PM10, PM2.5, VOCs, and NH3

from all sources and activities, 

including from point, nonpoint, nonroad mobile, and on-road mobile 

sources, for the time period from 2002 

to 2017 in Section 4. With respect to 

sources that report directly to the EPA, 

Massachusetts also included AMPD 

state summary data for SO2 and NOX

emissions for 2018 and 2019. 

The reductions achieved by 

Massachusetts emission control 

measures are seen in the emissions 

inventory. Based on Massachusetts’ SIP 

submission, NOX emissions have 

continuously declined in Massachusetts 

from 2002 through 2017, especially in 

the point, nonroad and onroad mobile 

sectors. NOX emissions are expected to 

continue to decrease as fleet turnover 

occurs and the older more polluting 

vehicles and equipment are replaced by 

newer, cleaner ones. Emissions of SO2

have shown a decline of 96% in 

Massachusetts over the period 2002 to 

2017, particularly in the point, nonroad 

and onroad mobile sectors. 

Massachusetts attributes the reductions 

in point emissions to controls on EGUs 

that were part of the first 

implementation period, fuel switching 

from coal and oil to natural gas, 

MassDEP’s low sulfur fuel rule, and the 

retirement of several large older coal 

and oil burning EGUs in the state. Since 

some components of the MANE–VU low 

sulfur fuel strategy were not 

implemented until 2018, and as MANE– 

VU states continue to adopt rules to 

implement the strategy, additional SO2

emissions reductions have likely been 

obtained since 2017 and are expected to 

continue into the future. 

In Massachusetts’ submission, table 

4–3 shows a summary of PM10

emissions from all NEI data categories 

point, nonpoint, non-road, and onroad 

for the period from 2002 to 2017 in 

Massachusetts. In Massachusetts, PM10

emissions steadily decreased in the 

point, nonpoint, and nonroad categories 

for the period from 2002 to 2017. The 

apparent increase in the onroad 

emissions is due to changes in emission 

inventory calculation methodologies, 

which resulted in higher particulate 

matter estimates. The variation in 

emissions in the nonpoint category is 

due to changes in calculation 

methodologies for residential wood 

burning and fugitive dust categories, 

which have varied significantly. 

Table 4–4 of Massachusetts’ 

submission shows a summary of PM2.5

emissions from all NEI data categories 

for the period from 2002 to 2017 in 

Massachusetts. PM2.5 emissions steadily 

decreased in the nonroad category for 

the period from 2002 to 2014. The 

majority of reductions came from the 

nonpoint category, which Massachusetts 

attributes to fuel combustion switching 

from oil to natural gas. The decrease in 

nonroad PM2.5 emissions is because of 

Federal new engine standards for 

nonroad vehicles and equipment. There 

is an overall decrease in onroad 

emissions due to Federal and State 

regulations. The increase in emissions 

in the onroad category from 2002 to 

2008 is due to changes in emission 

inventory calculation methodologies 

and a model change, as previously 

explained, which resulted in higher fine 

particulate matter estimates. 

Table 4–7 of Massachusetts’ 

submission shows VOC emissions from 

all NEI data categories for the period 

2002 to 2017 in Massachusetts. VOC 

emissions have shown a steady decline 

in Massachusetts over this period. VOC 

decreases were achieved in all sectors 

due to Federal new engine standards for 

onroad and nonroad vehicles and 

equipment, the National and State low 

emission vehicle programs, SIPapproved area source rules such as 

consumer products, portable fuel 

containers, paints, autobody refinishing, 

asphalt paving applications, and solvent 

cleaning operations, and point source 

controls. 

Table 4–8 of Massachusetts’ 

submission shows ammonia (NH3) 

emissions from all NEI data categories 

for the period 2002 to 2017 in 

Massachusetts. Ammonia decreases 

were achieved in the onroad sector due 

to Federal new engine standards for 

vehicles and equipment. Nonpoint 

increases and decreases from 2002 to 

2017 are due to reporting, grouping and 

methodology changes. There was little 

change to nonroad ammonia emissions. 

Overall, ammonia emissions have 

decreased from 2008 to 2017. 

The EPA is proposing to find that 

Massachusetts has satisfied the 

requirements of § 51.308(g)(4) by 

providing emissions information for 

NOX, SO2, PM10, PM2.5, VOCs, and NH3

broken down by type of source. 

Massachusetts uses the emissions 

trend data in the SIP submission to 

support the assessment that 

anthropogenic haze-causing pollutant 

emissions in Massachusetts have 

decreased during the reporting period 

and that changes in emissions have not 

limited or impeded progress in reducing 

pollutant emissions and improving 

visibility. The data Massachusetts 

presents for NOX, SO2, PM10, PM2.5, 

VOCs, and NH3 show consistently 

declining emissions of those pollutants. 

Massachusetts concludes that no 

significant changes have occurred that 

have impeded progress in reducing 

emissions and improving visibility 

during the reporting period. The EPA is 

proposing to find that Massachusetts 

has met the requirements of 

§ 51.308(g)(5). 

I. Requirements for State and Federal 

Land Manager Coordination 

Section 169A(d) of the Clean Air Act 

requires states to consult with FLMs 

before holding the public hearing on a 

proposed regional haze SIP, and to 

include a summary of the FLMs’ 

conclusions and recommendations in 

the notice to the public. In addition, 

section 51.308(i)(2)’s FLM consultation 

provision requires a state to provide 

FLMs with an opportunity for 

consultation that is early enough in the 

state’s policy analyses of its emission 

reduction obligation so that information 

and recommendations provided by the 

FLMs can meaningfully inform the 

state’s decisions on its long-term 

strategy. If the consultation has taken 

place at least 120 days before a public 

hearing or public comment period, the 

opportunity for consultation will be 

deemed early enough, but the 

opportunity for consultation must be 

provided at least sixty days before a 

public hearing or public comment 

period at the state level. Section 

51.308(i)(2) also requires that the 

consultation include the opportunity for 

the FLMs to discuss their assessment of 

visibility impairment in any Class I area 

and their recommendations on the 

development and implementation of 

strategies to address visibility 

impairment. Section 51.308(i)(3) 

requires states, in developing their 

implementation plans, to include a 

description of how they addressed 

FLMs’ comments. 

The states in the MANE–VU RPO 

conducted FLM consultation early in 

the planning process concurrent with 

the state-to-state consultation that 

formed the basis of the RPO’s decision 

making process. As part of the 

consultation, the FLMs were given the 

opportunity to review and comment on 

the technical documents developed by 

MANE–VU. The FLMs were invited to 

attend the intra- and inter-RPO 

consultations calls among states and at 

least one FLM representative was 

documented to have attended seven 

intra-RPO meetings and all inter-RPO 


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70See Appendix 20 ‘‘MANE–VU Regional Haze 

Consultation Report and Consultation 

Documentation—Final.’’ 

71 Id. 

72 Id. 

73 Id. 

74See Appendices 24 and 25. 

75See Appendix 43, ‘‘Summary of Public 

Comments and MassDEP Responses’’ at page 6. 

meetings. Massachusetts participated in 

these consultation meetings and calls.70

As part of this early engagement with 

the FLMs, on April 12, 2018, the NPS 

sent letters to the MANE–VU states 

requesting that they consider specific 

individual sources in their long-term 

strategies.71 NPS used an analysis of 

emissions divided by distance (Q/d) to 

estimate the impact of MANE–VU 

facilities. To select the facilities, NPS 

first summed 2014 NEI NOX, PM10, SO2, 

and SO4 emissions and divided by the 

distance to a specified NPS mandatory 

Class I Federal area. NPS summed the 

Q/d values across all MANE–VU states 

relative to Acadia, Mammoth Cave and 

Shenandoah National Parks, ranked the 

Q/d values relative to each Class I area, 

created a running total, and identified 

those facilities contributing to 80% of 

the total impact at each NPS Class I 

area. NPS applied a similar process to 

facilities in Maine but relative to just 

Acadia National Park. NPS merged the 

resulting lists of facilities and sorted 

them by their states. NPS suggested that 

a state consider those facilities 

comprising 80% of the Q/d total, not to 

exceed the 25 top ranked facilities. The 

NPS identified 10 facilities in 

Massachusetts in this letter.72

Massachusetts included the NPS initial 

letter in its proposed SIP.73 In a 

subsequent letter dated October 22, 

2018, NPS identified four municipal 

waste combustor facilities for which 

more control information was desired.74

Massachusetts detailed the emission 

controls and updates to the facilities to 

address the NPS’s request for more 

information, as discussed previously.75

On November 13, 2020, 

Massachusetts submitted a draft 

Regional Haze SIP to the U.S. Forest 

Service, the U.S. Fish and Wildlife 

Service, and the National Park Service 

for a 60-day review and comment period 

pursuant to 40 CFR 51.308(i)(2). 

Massachusetts received comments from 

the Forest Service and from the National 

Park Service by January 15, 2021. 

Massachusetts responded to the FLM 

comments and included a summary of 

the responses in Section 7.3 of its 

submission to EPA, in accordance with 

§ 51.308(i)(3). In satisfaction of 

§ 51.308(i)(4), Massachusetts explains 

that it will continue to consult with the 

FLMs through MANE–VU’s planning 

process (including participation in 

regular Technical Support Committee 

meetings that include FLM participation 

in the development of progress reports 

and the regional strategy for future RH 

SIP revisions), MassDEP regulatory and 

permit notification emails (which 

provide notification of air quality 

regulation amendments, SIP revisions, 

major new source review permits, 

ambient air monitoring plans), and 

MassDEP air quality advisory committee 

meetings. 

On April 7, 2021, MassDEP issued a 

notice of public hearing and comments 

and the availability of the draft Regional 

Haze SIP revision for 2018–2028 on 

MassDEP’s Public Notices and Hearings 

web page and on its SIP web page and 

emailed the notice to parties that have 

registered for the MassDEP public notice 

email list. The notice announced two 

video conference call public hearings on 

May 11, 2021 and the opportunity to 

submit written comments until May 14, 

2021. Appendix 43 of the Massachusetts 

SIP submittal contains a summary of 

public comments received and 

MassDEP’s responses. 

For the reasons stated above, the EPA 

proposes to find that Massachusetts has 

satisfied the requirements under 40 CFR 

51.308(i) to consult with the FLMs on 

its regional haze SIP for the second 

implementation period. 

J. Other Required Commitments 

Massachusetts’ July 22, 2021, SIP 

submission includes a commitment to 

revise and submit a regional haze SIP in 

2028, and every ten years thereafter. The 

state’s commitment includes submitting 

periodic progress reports in accordance 

with § 51.308(f) and a commitment to 

evaluate progress towards the 

reasonable progress goal for each 

mandatory Class I Federal area located 

within the state and in each mandatory 

Class I Federal area located outside the 

state that may be affected by emissions 

from within the state in accordance with 

§ 51.308(g). 

V. Proposed Action 

The EPA is proposing to approve the 

‘‘Massachusetts Regional Haze State 

Implementation Plan Revision for the 

Second Planning Period (2018–2028)’’, 

submitted July 22, 2021 and ‘‘Regional 

Haze SIP Revision for Massachusetts— 

Supplement’’ source specific 

requirements for Canal Generating 

Station, submitted May 26, 2022 as 

collectively satisfying the regional haze 

requirements for the second 

implementation period contained in 40 

CFR 51.308(f), (g), and (i). 

VI. Incorporation by Reference 

In this rule, the EPA is proposing to 

include in a final EPA rule regulatory 

text that includes incorporation by 

reference. In accordance with 

requirements of 1 CFR 51.5, the EPA is 

proposing to incorporate by reference 

‘‘Regional Haze SIP Revision for 

Massachusetts—Supplement’’ source 

specific requirements for Canal 

Generating Station (Permit number 21– 

AQ02F–011–APP), submitted May 26, 

2022. The EPA has made, and will 

continue to make, these documents 

generally available through https://

www.regulations.gov and at the EPA 

Region 1 Office (please contact the 

person identified in the FOR FURTHER

INFORMATION CONTACT section of this 

preamble for more information). 

VII. Statutory and Executive Order 

Reviews 

Under the CAA, the Administrator is 

required to approve a SIP submission 

that complies with the provisions of the 

CAA and applicable Federal regulations. 

42 U.S.C. 7410(k); 40 CFR 52.02(a). 

Thus, in reviewing SIP submissions, 

EPA’s role is to approve state choices, 

provided that they meet the criteria of 

the CAA. Accordingly, this action 

merely proposes to approve state law as 

meeting Federal requirements and does 

not impose additional requirements 

beyond those imposed by state law. For 

that reason, this proposed action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

October 4, 1993) and 13563 (76 FR 3821, 

January 21, 2011); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); and 


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• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the CAA. 

In addition, this proposed rulemaking 

action, pertaining to Massachusetts 

regional haze SIP submission for the 

second planning period, is not approved 

to apply on any Indian reservation land 

or in any other area where the EPA or 

an Indian tribe has demonstrated that a 

tribe has jurisdiction. In those areas of 

Indian country, the rule does not have 

tribal implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

Executive Order 12898 (Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations, 59 FR 7629, 

Feb. 16, 1994) directs Federal agencies 

to identify and address 

‘‘disproportionately high and adverse 

human health or environmental effects’’ 

of their actions on minority populations 

and low-income populations to the 

greatest extent practicable and 

permitted by law. EPA defines 

environmental justice (EJ) as ‘‘the fair 

treatment and meaningful involvement 

of all people regardless of race, color, 

national origin, or income with respect 

to the development, implementation, 

and enforcement of environmental laws, 

regulations, and policies.’’ EPA further 

defines the term fair treatment to mean 

that ‘‘no group of people should bear a 

disproportionate burden of 

environmental harms and risks, 

including those resulting from the 

negative environmental consequences of 

industrial, governmental, and 

commercial operations or programs and 

policies.’’ The air agency did not 

evaluate environmental justice 

considerations as part of its SIP 

submittal; the CAA and applicable 

implementing regulations neither 

prohibit nor require such an evaluation. 

EPA did not perform an EJ analysis and 

did not consider EJ in this action. 

Consideration of EJ is not required as 

part of this action, and there is no 

information in the record inconsistent 

with the stated goal of E.O. 12898 of 

achieving environmental justice for 

people of color, low-income 

populations, and Indigenous peoples. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Nitrogen dioxide, Ozone, 

Particulate matter, Sulfur oxides. 

Dated: December 20, 2023. 

David Cash, 

Regional Administrator, Region 1. 

[FR Doc. 2023–28573 Filed 1–9–24; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF THE INTERIOR 

Office of the Secretary 

43 CFR Part 2 

[DOI–2023–0027; DS65100000 

DWSN00000.000000 24XD4523WS 

DP.65102] 

RIN 1090–AB28 

Privacy Act Regulations; Exemption 

for the Law Enforcement Records 

Management System 

AGENCY: Office of the Secretary, Interior. 

ACTION: Notice of proposed rulemaking. 

SUMMARY: The Department of the 

Interior (DOI, Department) is proposing 

to amend its regulations to exempt 

certain records in the INTERIOR/DOI– 

10, DOI Law Enforcement Records 

Management System (LE RMS), system 

of records from one or more provisions 

of the Privacy Act of 1974 because of 

criminal, civil, and administrative law 

enforcement requirements. 

DATES: Submit comments on or before 

March 11, 2024. 

ADDRESSES: You may submit comments, 

identified by docket number [DOI– 

2023–0027] or Regulatory Information 

Number (RIN) Number 1090–AB28, by 

any of the following methods: 

• Federal eRulemaking Portal: 

https://www.regulations.gov. Follow the 

instructions for sending comments. 

• Email: DOI_Privacy@ios.doi.gov. 

Include docket number [DOI–2023– 

0027] or RIN 1090–AB28 in the subject 

line of the message. 

• U.S. mail or hand-delivery: Teri 

Barnett, Departmental Privacy Officer, 

U.S. Department of the Interior, 1849 C 

Street NW, Room 7112, Washington, DC 

20240. 

Instructions: All submissions received 

must include the agency name and 

docket number [DOI–2023–0027] or RIN 

1090–AB28 for this rulemaking. All 

comments received will be posted 

without change to https://

www.regulations.gov, including any 

personal information provided. 

Docket: For access to the docket to 

read background documents or 

comments received, go to https://

www.regulations.gov. 

FOR FURTHER INFORMATION CONTACT: Teri 

Barnett, Departmental Privacy Officer, 

U.S. Department of the Interior, 1849 C 

Street NW, Room 7112, Washington, DC 

20240, DOI_Privacy@ios.doi.gov or (202) 

208–1605. In compliance with the 

Providing Accountability Through 

Transparency Act of 2023, the plain 

language summary of the proposal is 

available on Regulations.gov in the 

docket for this rulemaking. 

SUPPLEMENTARY INFORMATION: 

Background 

The Privacy Act of 1974, as amended, 

5 U.S.C. 552a, governs the means by 

which the U.S. Government collects, 

maintains, uses, and disseminates 

personally identifiable information. The 

Privacy Act applies to information about 

individuals that is maintained in a 

‘‘system of records.’’ A system of 

records is a group of any records under 

the control of an agency from which 

information about an individual is 

retrieved by the name of the individual 

or by some identifying number, symbol, 

or other identifying particular assigned 

to the individual. See 5 U.S.C. 

552a(a)(4) and (5). 

Individuals may request access to 

records containing information about 

themselves under the Privacy Act of 

1974, 5 U.S.C. 552a(b), (c) and (d). 

However, the Privacy Act authorizes 

Federal agencies to exempt systems of 

records from access by individuals 

under certain circumstances, such as 

where the access or disclosure of such 

information would impede national 

security or law enforcement efforts. 

Exemptions from Privacy Act provisions 

must be established by regulation 

pursuant to 5 U.S.C. 552a(j) and (k). 

The DOI Office of Law Enforcement 

and Security (OLES) maintains the 

INTERIOR/DOI–10, DOI Law 

Enforcement Records Management 

System (LE RMS), system of records to 

help DOI and its law enforcement 

bureaus and offices carry out 

responsibilities to prevent, detect, and 

investigate known and suspected 

criminal activity; detain and apprehend 

those committing crimes on DOI 

properties or Tribal reservations; 

manage investigations and law 

enforcement activities including use of 

force, critical incidents, property 

damage claims, traffic accidents, and 

domestic issues; and prevent visitor 

accidents or injuries on DOI properties 

or Tribal reservations. The system also 

contains statements and records of 

complaints, reports, correspondence 

from or about complainants, subjects, 

and victims of law enforcement 

investigations. Accordingly, records in 

the system are used during 

investigations and law enforcement 

activities and related criminal 


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