58178 Federal Register / Vol. 88, No. 164 / Friday, August 25, 2023 / Proposed Rules 

submissions in response to this 

document, see DHS’s eRulemaking 

System of Records notice (85 FR 14226, 

March 11, 2020). 

List of Subjects in 33 CFR Part 117 

Bridges. 

For the reasons discussed in the 

preamble, the Coast Guard proposes to 

amend 33 CFR part 117 as follows: 

Part 117—Drawbridge Operation 

Regulations 

■ 1. The authority citation for part 117 

continues to read as follows: 

Authority: 33 U.S.C. 499; 33 CFR 1.05–1; 

DHS Delegation No. 00170.1, Revision No. 

01.3. 

■ 2. Revise § 117.799(e) to read as 

follows: 

§ 117.799 Long Island, New York Inland 

Waterway from East Rockaway Inlet to 

Shinnecock Canal. 

* * * * * 

(e) The draw of the Atlantic Beach 

Bridge across Reynolds Channel, mile 

0.4, shall operate as follows: 

(1) From October 1 through May 14 

the draw shall open on signal from 8 

a.m. to midnight. 

(2) From midnight to 8 a.m. yearround, the draw shall open on signal if 

at least eight hours notice is given. 

(3) From May 15 through September 

30, except that it need be opened only 

on the hour and half-hour from 4 p.m. 

to 7 p.m. on weekdays and from 11 a.m. 

to 9 p.m. on Saturdays, Sundays, 

Memorial Day, Independence Day, and 

Labor Day. 

(4) From May 15 through September 

30, from two hours before to one hour 

after predicted high tide. Predicted high 

tide occurs 10 minutes earlier than that 

predicted for Sandy Hook, as given in 

the tide table published by the National 

Oceanic and Atmospheric 

Administration. 

* * * * * 

Dated: August 20, 2023. 

J. W. Mauger, 

Rear Admiral, U.S. Coast Guard, Commander, 

First Coast Guard District. 

[FR Doc. 2023–18322 Filed 8–24–23; 8:45 am] 

BILLING CODE 9110–04–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R03–OAR–2022–0912; FRL–11269– 

01–R3] 

Approval and Promulgation of Air 

Quality Implementation Plans; 

Maryland; 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 the 

State of Maryland on February 8, 2022, 

as satisfying applicable requirements 

under the Clean Air Act (CAA) and 

EPA’s Regional Haze Rule for the 

program’s second implementation 

period. Maryland’s 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 September 25, 

2023. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R03– 

OAR–2022–0912 at 

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 

www.epa.gov/dockets/commenting-epadockets. 

FOR FURTHER INFORMATION CONTACT: 

Adam Yarina, U.S. Environmental 

Protection Agency, Region 3, 1600 John 

F. Kennedy Boulevard, Philadelphia, 

Pennsylvania 19103–2852, at (215) 814– 

2108, or by email at yarina.Adam@

epa.gov. 

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. EPA’s Evaluation of Maryland’s Regional 

Haze Submission for the Second 

Implementation Period 

A. Background on Maryland’s First 

Implementation Period SIP Submission 

B. Maryland’s 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 

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. Statutory and Executive Order Reviews 

I. What action is the EPA proposing? 

On February 8, 2022, the Maryland 

Department of the Environment (MDE) 

submitted a revision to its SIP to 

address regional haze for the second 

implementation period. MDE made this 

SIP submission to satisfy the 

requirements of the CAA’s regional haze 


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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) and (d)(3). 

program pursuant to CAA sections 169A 

and 169B and 40 CFR 51.308. The EPA 

is proposing to find that the Maryland 

regional haze SIP submission for the 

second implementation period meets 

the applicable statutory and regulatory 

requirements and thus proposes to 

approve Maryland’s 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 35714 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 35714 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 

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 


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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 

35714 at 35731–32, July 1, 1999. 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. www.epa.gov/visibility/ 

guidance-regional-haze-state-implementationplans-second-implementation-period. 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. www.epa.gov/system/files/ 

documents/2021-07/clarifications-regardingregional-haze-state-implementation-plans-for-thesecond-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. www.epa.gov/visibility/ 

technical-guidance-tracking-visibility-progresssecond-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. www.epa.gov/visibility/memo-andtechnical-addendum-ambient-data-usage-andcompleteness-regional-haze-program. The EPA 

Office of Air Quality Planning and Standards, 

Research Triangle Park (June 3, 2020). 

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) and 

(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) and (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) and (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 

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 


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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 document, 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. 

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, 40 CFR 

51.308(f) lays out the process by which 

states determine what constitutes their 

long-term strategies, with the order of 

the requirements in 40 CFR 51.308(f)(1) 

through (3) generally mirroring the 

order of the steps in the reasonable 

progress analysis 14 and 40 CFR 

51.308(f)(4) through (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) and (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 longterm 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. 

Additionally, as further explained 

below, the RHR at 40 CFR 

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

‘‘additional factors’’ 15 that states must 

consider in developing their long-term 

strategies. See 40 CFR 51.308(f)(2). 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 long-term 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) and (3). 

In addition to satisfying the 

requirements at 40 CFR 51.308(f) related 

to reasonable progress, the regional haze 

SIP submissions revisions due by July 

31, 2021, for the second implementation 

period must address the requirements in 

40 CFR 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 

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 


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58182 Federal Register / Vol. 88, No. 164 / Friday, August 25, 2023 / Proposed Rules 

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 document 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, January 10, 2017: ‘‘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 3078 at 

3093, January 10, 2017. 

states contribute to visibility 

impairment in at least one Class I area, 

64 FR 35720–22, July 1, 1999, 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 40 CFR 

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 40 CFR 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 3078 at 3103–05, 

January 10, 2017. 

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) and 

(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, 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 3078 at 3107 footnote 116, 

January 10, 2017. 

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 40 

CFR 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 

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 


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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 3078 at 3088, January 10, 2017. 

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. 

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 nonair 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 3078 at 3091, January 

10, 2017. 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 

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 


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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 3078 at 3108–09, January 10, 2017 

(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 Nat’l Parks Conservation Ass’n v. 

EPA, 803 F.3d 151, 165 (3d Cir. 2015); Alaska Dep’t 

of Envtl. Conservation v. EPA, 540 U.S. 461, 485, 

490 (2004). 

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. 

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, 40 CFR 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, 40 CFR 

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 

40 CFR 51.308(f)(2), measures that are 

necessary to make reasonable progress 

towards the national visibility goal must 

be included in a state’s long-term 

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 40 CFR 

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, 40 CFR 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 

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 


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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. 

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, 

40 CFR 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 3078 at 3091, 

January 10, 2017. 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) and (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 nonSIP 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, 40 CFR 

51.308(f)(3)(i) requires that ‘‘[t]he longterm 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 shows 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 3078 at 

3097–98, January 10, 2017. 

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 

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 


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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. 

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 3078 

at 3093, 3099–3100, January 10, 2017; 

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) and (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) and (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 40 

CFR 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 3078 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, 40 CFR 51.308(g)(3) requires 

states 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 


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31EPA determined that ‘‘there is more than 

sufficient evidence to support our conclusion that 

emissions from each of the 48 contiguous states and 

the District of Columba may reasonably be 

anticipated to cause or contribute to visibility 

impairment in a Class I area.’’ 64 FR 35714 at 

35721, July 1, 1999. Hawaii, Alaska, and the U.S. 

Virgin Islands must also submit regional haze SIPs 

because they contain Class I areas. 

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) 

and (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) and (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. EPA’s Evaluation of Maryland’s 

Regional Haze Submission for the 

Second Implementation Period 

A. Background on Maryland’s First 

Implementation Period SIP Submission 

MDE submitted its regional haze SIP 

for the first implementation period to 

the EPA on February 13, 2012. The EPA 

approved Maryland’s first 

implementation period regional haze 

SIP submission on July 6, 2012 (77 FR 

39938, July 6, 2012), effective August 6, 

2012. EPA’s approval included the 

portions of the plan that addressed the 

reasonable progress requirements and 

Maryland’s implementation of Best 

Available Retrofit Technologies (BART) 

on eligible sources. 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), 

Maryland was also responsible for 

submitting a five-year progress report as 

a SIP revision for the first 

implementation period, which it did on 

August 9, 2017. The EPA approved the 

progress report on November 26, 2018 

(83 FR 60363, November 26, 2018), 

effective December 26, 2018. 

B. Maryland’s 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 February 8, 2022, MDE submitted a 

revision to the Maryland SIP to address 

its regional haze obligations for the 

second implementation period, which 

runs through 2028. Maryland made its 

2020 Regional Haze SIP submission 

available for public comment on 

December 1, 2021 through January 4, 

2022. MDE received and responded to 

public comments and included the 

comments and responses to those 

comments in their submission. 

The following sections describe 

Maryland’s SIP submission, including 

analyses conducted by MANE–VU and 

Maryland’s determinations based on 

those analyses, Maryland’s 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 document also contains 

EPA’s evaluation of Maryland’s 

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 40 CFR 

51.308(f)(2), which requires each state’s 

plan to include a long-term strategy that 

addresses regional haze in such Class I 

areas. 

The EPA explained in the 1999 RHR 

preamble that the CAA section 

169A(b)(2) requirement that states 

submit SIPs to address visibility 

impairment establishes ‘‘an ‘extremely 

low triggering threshold’ in determining 

which States should submit SIPs for 

regional haze.’’ 64 FR 35714 at 35721, 

July 1, 1999. In concluding that each of 

the contiguous 48 states and the District 

of Columbia meet this threshold,31 the 

EPA relied on ‘‘a large body of evidence 

demonstrat[ing] that long-range 

transport of fine PM contributes to 

regional haze,’’ id., including modeling 

studies that ‘‘preliminarily 


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32The contribution assessment methodologies for 

MANE–VU Class I areas are summarized in 

Appendix 1 of Maryland’s SIP submittal, which can 

be found in the docket, ‘‘Selection of States for 

MANE–VU Regional Haze Consultation (2018).’’ 

33 Id. 

34See docket EPA–R03–OAR–2022–0912 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 docket document, ‘‘2016 MANE VU Source 

Contribution Modeling Report (CALPUFF Modeling 

of Large EGUs and Industrial Sources) (April 4, 

2017)’’. 

37Brandon Shores (Unit 1 & Unit 2), CP Crane 

(Unit 1 & Unit 2), Chalk Point (Units 1 & 2), 

Dickerson (Units 1–3), Herbert Wager (Unit 3 & 

Units 1, 2, and 4), and Morgantown (Unit 1 and 

Unit 2). 

38Luke Paper Company (Unit 0018, Unit 0019, 

and Unit 0235), Naval Support Facility Indian 

Head, and Sparrows Point, LLC (Unit 0939 and Unit 

0941). 

39See docket document, ‘‘2016 MANE VU Source 

Contribution Modeling Report (CALPUFF Modeling 

of Large EGUs and Industrial Sources) (April 4, 

2017)’’. 

40See Section 2.4 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022), and docket documents ‘‘MDE 

SO2 2010 NAAQS SIP for Baltimore and Anne 

Arundel NA (January 31, 2020)’’, and ‘‘MDE SO2

2010 NAAQS SIP for Baltimore and Anne Arundel 

NA (January 31, 2020)—Appendix B—Consent 

Orders, Permits, and Plan Approvals’’. 

41See docket document, ‘‘MDE EPA Chalk Point 

Units 1&2 Retired Unit Exemption Forms 6–4–21 

(June 4, 2021)’’. 

42See Appendix 19, ‘‘Herbert A. Wagner 

Generating Station Consent Order’’. 

demonstrated that each State not having 

a Class I area had emissions 

contributing to impairment in at least 

one downwind Class I area.’’ Id. at 

35722. In addition to the technical 

evidence supporting a conclusion that 

each state contributes to existing 

visibility impairment, the EPA also 

explained that the second half of the 

national visibility goal—preventing 

future visibility impairment—requires 

having a framework in place to address 

future growth in visibility-impairing 

emissions and makes it inappropriate to 

‘‘establish criteria for excluding States 

or geographic areas from consideration 

as potential contributors to regional 

haze visibility impairment.’’ Id. at 

35721. Thus, the EPA concluded that 

the agency’s ‘‘statutory authority and 

the scientific evidence are sufficient to 

require all States to develop regional 

haze SIPs to ensure the prevention of 

any future impairment of visibility, and 

to conduct further analyses to determine 

whether additional control measures are 

needed to ensure reasonable progress in 

remedying existing impairment in 

downwind Class I areas.’’ Id. at 35722. 

EPA’s 2017 revisions to the RHR did not 

disturb this conclusion. See 82 FR 3078 

at 3094, January 10, 2017. 

Maryland has no mandatory Class I 

Federal area within its borders, but has 

previously been shown to have sources 

with emissions that impact visibility at 

downwind mandatory Class I Federal 

areas. 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 

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

Maryland had ten EGU sources 37 and 

six industrial/institutional sources 38

that were included in the MANE–VU 

CALPUFF modeling analysis.39 The 

EGU facilities Brandon Shores, Chalk 

Point, Herbert Wagner, and Morgantown 

were identified as among the Top 25 

most impactful EGU facilities for 

Shenandoah National Park Class I area, 

and EGU facility CP Crane was also 

identified as among the Top 25 most 

impactful EGU facilities for Dolly Sods 

Wilderness Class I area. EGU facilities 

Brandon Shores, Chalk Point, CP Crane, 

Herbert Wagner, and Morgantown were 

also among the EGU facilities identified 

as having the Top Impacting EGU 

stacks. The Luke Paper Company and 

Sparrows Point industrial facilities were 

identified as among the Top 25 visibility 

impacting industrial/institutional 

sources for Acadia National Park, 

Brigantine National Wilderness Area, 

Great Gulf Wilderness, Lye Brook 

Wilderness, Dolly Sods Wilderness, and 

Shenandoah National Park Class I areas. 

The Indian Head Naval Support Facility 

was also identified as among the Top 25 

visibility impacting industrial/ 

institutional sources for Dolly Sods 

Wilderness and Shenandoah National 

Park. 

In its submittal, Maryland indicates 

that Brandon Shores Generating Station 

has agreed via legal consent agreement 

to cease coal combustion at the site by 

2026.40 Maryland indicates that Chalk 

Point Generation Station ceased coal 

operations in 2021 and closed, and that 

Maryland subsequently filed a Retired 

Unit Exemption form with EPA, 

specifying that the Chalk Point units 

identified are permanently shut down 

and cannot be restarted, and that a new 

owner would be required to obtain all 

new permits.41 Maryland also indicates 

that Herbert Wagner Generating Station 

has agreed to cease coal combustion by 

2026; MDE and Herbert Wagner owner/ 

operator Raven Power, Fort Smallwood 

LLC, entered into a legal consent order 

requiring Raven Power to cease coal 

combustion at Herbert Wager no later 

than January 1, 2026.42 Maryland 


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43See Section 2.6.1 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022), and docket documents ‘‘MDE 

SO2 2010 NAAQS SIP for Baltimore and Anne 

Arundel NA (January 31, 2020)’’, and ‘‘MDE SO2

2010 NAAQS SIP for Baltimore and Anne Arundel 

NA (January 31, 2020)—Appendix B—Consent 

Orders, Permits, and Plan Approvals’’. 

44See docket documents, ‘‘Verso Luke Paper— 

Luke MD Title V Permit Termination (May 7, 

2020)’’ and ‘‘Verso Luke Paper—Verso Luke Close 

Out Letter (May 8, 2020)’’. 

45See docket document, ‘‘MDE Sparrows Point 

Administrative Consent Order (September 12, 

2014)’’. 

46See docket document, ‘‘MDE EPA Indian Head 

Boiler Decommision letter (January 29, 2016)’’. 

47See docket document, ‘‘MANE–VU 

Contributions to Regional Haze in the Northeast and 

Mid-Atlantic United States (August 2006)’’. 

48See ‘‘Table 2–2: Q/d results using 2011 and 

2018 inventory data for 32 states’’, of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

49Acadia National Park, Moosehorn National 

Wildlife Refuge, and Roosevelt Campobello 

International Park in Maine; Brigantine Wilderness 

in New Jersey; Great Gulf Wilderness and 

Presidential Range-Dry River Wilderness in New 

Hampshire; and Lye Brook Wilderness in Vermont. 

50See docket document, ‘‘2016 MANE–VU 

Source Contribution Modeling Report (April 4, 

2017),’’ Tables 1 through 33. 

51The Class I areas analyzed were Acadia 

National Park in Maine, Brigantine Wilderness in 

New Jersey, Great Gulf Wilderness in New 

Hampshire, Lye Brook Wilderness in Vermont, 

Moosehorn Wilderness in Maine, Shenandoah 

National Park in Virginia, James River Face 

Wilderness in Virginia, and Dolly Sods/Otter Creek 

Wildernesses in West Virginia. 

52As explained more fully in Section IV.E.1 of 

this document, MANE–VU refers to each of the 

components of its overall strategy as an ‘‘Ask ‘‘of 

its member states. 

53The MANE–VU Consultation Report (Appendix 

7) 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.’’ 

included the consent order as part of its 

SIP submittal. Maryland also indicates 

that CP Crane Generating Station has 

disabled its coal boilers and agreed via 

legal consent agreement to never again 

stockpile or burn coal at the facility.43

Maryland further indicates that the Luke 

Paper Company industrial facility has 

ceased operations, closed and 

relinquished their air permits as of May 

29, 2020; 44 that the Sparrows Point 

industrial facility was retired as of 

December 31, 2012; 45 and that the 

primary emissions units at the Indian 

Head Naval Support Facility, which 

consisted of three coal- and No. 6 fuel 

oil-fired boilers at the Goddard Steam 

Plant, were permanently shut down in 

2014.46

The second MANE–VU contribution 

analysis used a meteorologically 

weighted Q/d calculation to assess 

states’ contributions to visibility 

impairment at MANE–VU Class I 

areas.47 This analysis focused 

predominantly on SO2 emissions and 

used cumulative SO2 emissions from a 

source and a state for the variable ‘‘Q,’’ 

and the distance of the source or state 

to the IMPROVE monitor receptor at a 

Class I area as ‘‘d.’’ The result is then 

multiplied by a constant (Ci), which is 

determined based on the prevailing 

wind patterns. MANE–VU selected a 

meteorologically weighted Q/d analysis 

as an inexpensive initial screening tool 

that could easily be repeated to 

determine which states, sectors, or 

sources have a larger relative impact 

and warrant further analysis. MANE– 

VU updated its analysis in 2016 using 

2011 emissions and 2018 projected 

emissions, which Maryland included as 

part of its submittal. MANE–VU’s 

analysis estimated Maryland’s 2018 

sulfate contribution at 3.77% at Acadia 

National Park, 8.89% at Brigantine 

Wilderness, 3.36% at Great Gulf 3.80% 

at Lye Brook, and 3.35% at Moosehorn 

Class I areas based on maximum daily 

impact.48 Although MANE–VU did not 

originally estimate nitrate impacts, the 

MANE–VU Q/d analysis was 

subsequently extended to account for 

nitrate contributions from NOX

emissions and to approximate the 

nitrate impacts from area and mobile 

sources. MANE–VU therefore developed 

a ratio of nitrate to sulfate impacts based 

on the previously described CALPUFF 

modeling and applied those to the 

sulfate Q/d results in order to derive 

nitrate contribution estimates. Several 

states did not have CALPUFF nitrate to 

sulfate ratio results, however, because 

there were no point sources modeled 

with CALPUFF. 

In order to develop a final set of 

contribution estimates, MANE–VU 

weighted the results from both the Q/d 

and CALPUFF analyses. The MANE–VU 

mass-weighted sulfate and nitrate 

contribution results were reported for 

the MANE–VU Class I areas (the Q/d 

summary report included results for 

several non-MANE–VU areas as well). If 

a state’s contribution to sulfate and 

nitrate concentrations at a particular 

Class I area was 2 percent or greater, 

MANE–VU regarded that state as 

contributing to visibility impairment in 

that area. According to MANE–VU’s 

analyses, sources in Maryland were 

found to contribute to visibility 

impairment at all seven downwind 

MANE–VU Class I areas,49 as well as 

VISTA Class I areas including James 

River Face and Shenandoah National 

Park in Virginia and Dolly Sods 

Wilderness and Otter Creek Wilderness 

in West Virginia.50 MANE–VU 

determined that modeled emissions 

sources that have the potential for 3.0 

Mm¥1 or greater visibility impacts at 

any MANE–VU Class I area should 

perform a four-factor analysis for 

reasonable installation or upgrade to 

emissions controls. Maryland indicated 

in its submittal that it agrees with 

MANE–VU’s approach and assessment. 

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 35714 at 35721, July 1, 

1999, and this determination was not 

changed in the 2017 RHR. Critically, the 

statute and regulation both require that 

the cause-or-contribute assessment 

consider all emissions of visibilityimpairing 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. 

First, 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 five Class I areas 

within MANE–VU states and three 

additional, nearby Class I areas.51 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’’ 52 of states and 

sources both within and upwind of 

MANE–VU.53 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 Maryland’s 

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 Maryland emissions on 

downwind Class I areas. However, the 

analyses did not account for all 


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54See docket documents, ‘‘MANE–VU IntraRegional Ask Final 8–25–2017 (August 25, 2017)’’ 

and ‘‘MANE–VU Inter-Regional Ask Final 8–25– 

2017 (August 25, 2017). 

55See MD Regional Haze SIP submission Section 

2.3 (Page 8). 

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. While Maryland noted that 

contributions from other states are 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 

Maryland 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, it is clear 

that emissions from Maryland 

contribute to visibility impairment at 

out-of-state Class I areas. 

Regardless, we note that Maryland did 

determine that sources and emissions 

within the state contribute to visibility 

impairment at out-of-state Class I areas. 

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 five 

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.54 Maryland’s submittal 

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 MANE–VU has laid out for its 

states. Maryland 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 Maryland 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. Although we have 

concerns regarding some aspects of 

MANE–VU’s technical analyses 

supporting states’ contribution 

determinations, we propose to find that 

Maryland has satisfied the applicable 

requirements for making reasonable 

progress towards natural visibility 

conditions in Class I areas that may be 

affected be 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). 

Maryland does not have any 

mandatory Class I areas within its 

borders; therefore, Section 51.308(f)(1) 

and its requirements do not apply. 

E. Long-Term Strategy for Regional Haze 

1. Maryland’s 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 document, 

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 40 

CFR 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)(iii). 

The following section summarizes 

how Maryland’s SIP submission 

addressed the requirements of 40 CFR 

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

MANE–VU’s development of the six 

Asks and how Maryland addressed 

each. The EPA’s evaluation of 

Maryland’s SIP revision with regard to 

the same is contained in the following 

Section IV.E.2 of this document. 

Maryland’s SIP submission describes 

how it plans to meet the long-term 

strategy requirements defined by the 

state and MANE–VU and provides that 

‘‘[t]hese long-term strategies are referred 

to as the ‘Asks’.’’ 55

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 40 CFR 51.308(f). Where an RPO 

has performed source selection and/or 

four-factor analyses (or considered the 

five additional factors in 40 CFR 

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 40 CFR 

51.308(f)(2)(i) so long as the states have 


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56See Appendix 8, ‘‘Statement of the MidAtlantic/Northeast Visibility Union (MANE–VU) 

Concerning a Course of Action within MANE–VU 

toward Assuring Reasonable Progress for the 

Second Regional Haze Implementation Period 

(2018–2028), (August 2017); and Appendix 7 

‘‘MANE–VU Regional Haze Consultation Report’’ 

(July 27, 2018).’’ 

57 Id. 

58 Id. 

59The period of 2012–2016 was the most recent 

period for which data was available at the time of 

analysis. 

60See docket document, NESCAUM— 

Contributions to Regional Haze Preliminary Update 

Through 2007 (March 21, 2012) 

61See docket document, ‘‘Assessment of 

Reasonable Progress for Regional Haze In MANE– 

VU Class I Areas (July 2007) (MACTEC Reasonable 

Progress Report)’’ 

62See docket document, ‘‘MANE–VU IntraRegional Ask Final (August 25, 2017)’’. 

63See docket document, ‘‘MANE–VU TSD on 

Measures to Mitigate the Visibility Impacts of 

Construction Activities in the MANE–VU Region 

(September 2006).’’ 

64See docket document ‘‘NESCAUM—Baseline 

and Natural Background Visibility Conditions 

(December 2006).’’ 

65See docket document, ‘‘2016 Updates to the 

Assessment of Reasonable Progress for Regional 

Haze in MANE–VU Class I Areas (January 31, 

2016).’’ 

66See docket document ‘‘MANE–VU Four Factor 

Data Collection Memo (March 30, 2017)’’ at 1. 

a reasonable basis to do so and all state 

participants in the RPO process have 

approved the technical analyses. 40 CFR 

51.308(f)(3)(iii). States may also satisfy 

the requirement of 40 CFR 

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. 

Maryland 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.56 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.’’ 57 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.’’ 58

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 Maryland’s 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) 59 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 

impacts in recent years. The technical 

analyses used by Maryland are included 

or referenced in their submission, and 

are as follows: 

• Selection of States for MANE–VU 

Regional Haze Consultation (2018) 

(MANE–VU, September 2017) 

(Appendix 1); 

• Contributions to Regional Haze in 

the Northeast and Mid-Atlantic United 

States: Preliminary Update through 

2007 (NESCAUM, March 2012); 60

• MANE–VU Updated Q/d*C 

Contribution Assessment (MANE–VU, 

April 2016) (Appendix 3); 

• 2016 MANE–VU Source 

Contribution Modeling Report— 

CALPUFF Modeling of Large Electrical 

Generating Units and Industrial Sources 

(MANE–VU, May 2006) (Appendix 4); 

• Assessment of Reasonable Progress 

for Regional Haze in MANE–VU Class I 

areas (referred to as the MACTEC 

Report) MACTEC (July 2007); 61

• Statement of the Mid-Atlantic/ 

Northeast Visibility Union (MANE–VU) 

Concerning a Course of Action within 

MANE–VU toward Assuring Reasonable 

Progress for the Second Regional Haze 

Implementation Period (2018–2028) 

(August 2017); 62

• Statement of the Mid-Atlantic/ 

Northeast Visibility Union (MANE–VU) 

Concerning a Course of Action In 

Contributing States Located Upwind of 

MANE–VU Toward Assuring 

Reasonable Progress for the Second 

Regional Haze Implementation Period 

(2018–2028) (Appendix 8); 

• Technical Support Document for 

the 2011 Northeastern U.S. Gamma 

Emission Inventory (January 2018) 

(Appendix 10); 

• Ozone Transport Commission/MidAtlantic Northeastern Visibility Union 

2011 Based Modeling Platform Support 

Document—October 2018 Update 

(October 2018) (Appendix 11); 

• The Nature of Fine Particle and 

Regional Haze Air Quality Problems in 

the MANE–VU Region: A Conceptual 

Description (NESCAUM, November 

2006, Revised August 2010) (Appendix 

12); 

• Mid-Atlantic/Northeast U.S. 

Visibility Data 2004–2017 (2nd RH SIP 

Metrics) (MANE–VU, December 2018) 

(Appendix 13); 

• Additional MANE–VU 

documentation for establishing 3.0 

Mm¥1 Threshold (Appendix 17); 

• 20% Most Impaired Days Based on 

Deciviews, as Detailed in 

Recommendation on Approaches to 

Selecting the 20% Most Impaired Days 

(March 2, 2017) (Appendix 18); 

• Technical Support Document on 

Measures to Mitigate the Visibility 

Impacts of Construction Activities in the 

MANE–VU Region (MANE–VU, 

September 2006); 63

• Baseline and Natural Background 

Visibility Conditions (NESCAUM, 

December 2006); 64

• 2016 Updates to the Assessment of 

Reasonable Progress for Regional Haze 

in MANE–VU Class I Areas, January 31, 

2016 (MARAMA, January 31, 2016); 65

To support development of the Asks, 

MANE–VU gathered information on the 

four statutory factors for six source 

sectors it determined, based on an 

examination of annual emission 

inventories, ‘‘had emissions 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.66 MANE–VU also collected 

data on individual sources within the 

EGU, ICI boiler, and cement kiln 


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67See docket document, ‘‘2016 Updates to the 

Assessment of Reasonable Progress for Regional 

Haze in MANE–VU Class I Areas (January 31, 

2016).’’ 

68 Id. 

69See docket document ‘‘MANE–VU Four Factor 

Data Collection Memo (March 30, 2017).’’ 

70See docket document ‘‘MANE–VU Status of the 

Top 167 Stacks from the 2008 MANE–VU Ask (July 

2016).’’ 

71See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

72See Section 2.5.1 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

73See Table 2–8, Figure 2–3, and Figure 2–4 of 

the MD Regional Haze SIP for the Second 

Implementation Period 2018–2028 (February 8, 

2022). 

74See Table 2–7 and Figure 2–3 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

75See Appendix 4, ‘‘2016 MANE VU Source 

Contribution Modeling Report: CALPUFF Modeling 

of Large Electrical Generating Units and Industrial 

Sources (April 4, 2017)’’. 

76See docket documents, ‘‘Verso Luke Paper— 

Luke MD Title V Permit Termination (May 7, 

2020)’’ and ‘‘Verso Luke Paper—Verso Luke Close 

Out Letter (May 8, 2020)’’. 

77See Appendix 19, Herbert A. Wagner 

Generating Station Consent Order. 

78See Section 2.5.2 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

79 41:20 Md. R. 1111 (Maryland Register, Volume 

41, Issue 20, dated October 3, 2014), effective 

October 13, 2014. 

80 45:24 Md. R. 1162 (Maryland Register, Volume 

45, Issue 24, dated November 26, 2018), effective 

December 6, 2018. 

sectors.67 Information for the six sectors 

included explanations of technically 

feasible control options for SO2 or NOX, 

illustrative cost-effectiveness estimates 

for a range of model units and control 

options, sector-wide cost 

considerations, potential time frames for 

compliance with control options, 

potential energy and non-air-quality 

environmental impacts of certain 

control options, and how the remaining 

useful lives of sources might be 

considered in a control analysis.68

Source-specific data included SO2

emissions 69 and existing controls 70 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 requests that states 

‘‘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’’ at 

EGUs ‘‘with a nameplate capacity larger 

than or equal to 25 MW with already 

installed NOX and/or SO2 controls’’.71

In its submission, Maryland stated that 

COMAR 21.11.27—Emission 

Limitations for Power Plants (Maryland 

Healthy Air Act) ‘‘caps NOX emissions 

on an ozone season and annual basis for 

each coal-fired EGU in Maryland.’’ In 

addition, Maryland also stated that 

COMAR 26.11.40—NOX Ozone Season 

Emission Caps for Non-trading Large 

NOX Units ‘‘assures optimization of 

post-combustion (Selective Catalytic 

Reduction (SCR) and Selective NonCatalytic Reduction (SNCR)) NOX

controls on coal-fired EGUs and sets 

NOX Indicator Rates for each unit to 

assure optimization.’’ 72 Maryland 

credited these regulations with 

‘‘reducing annual NOX mass emissions 

by almost 95% compared to 2002 

levels.’’ 73 Regarding SO2 emission 

controls, Maryland stated that COMAR 

21.11.27—Emission Limitations for 

Power Plans (Maryland Healthy Air Act) 

‘‘caps SO2 emissions limits on an 

annual basis for each coal-fired EGU in 

Maryland. All non-fluidized bed base 

load coal-fired units are equipped with 

Flue Gas Desulfurization (FGD) except 

one. H.A. Wagner Unit 3 is the only 

coal-fired EGU not equipped with an 

FGD. H.A. Wagner Unit 3 is named as 

a unit requiring a four-factor analysis 

and is analyzed further in Section 

2.5.2.’’ Maryland also stated that permit 

limits associated with a federally 

enforceable consent order for the Anne 

Arundel and Baltimore County SO2

nonattainment area include SO2

emission limits. Taken together, 

Maryland credited these requirements 

with ‘‘reducing the annual SO2 mass 

emissions by over 95% compared to 

2002 levels’’.74 Maryland therefore 

concluded it is meeting Ask 1. 

MANE–VU Ask 2 requests that states 

‘‘perform a four-factor analysis for 

reasonable installation or upgrade to 

emissions controls’’ at ‘‘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’’. MANE–VU 

developed its Ask 2 list of sources for 

analysis by performing modeling and 

identifying facilities with the potential 

for 3.0 inverse megameters (Mm¥1) or 

greater impacts on visibility at any Class 

I area in the MANE–VU region. MANE– 

VU identified emission sources at the 

Herbert A. Wagner Generating Facility 

in Anne Arundel County, Maryland and 

at the Verso Luke Paper Company 

facility in Allegany County, Maryland as 

having the potential for 3.0 Mm¥1 or 

greater visibility impacts at any MANE– 

VU Class I area; 75 specifically, Unit 3 at 

Herbert A. Wagner Generating Facility 

and Units 001–0011–3–0018 and 001– 

0011–3–0019 at Verso Luke Paper 

Company. Maryland stated that ‘‘Luke 

Paper Company ceased operations, 

closed, and relinquished their air 

permits’’, and that this information was 

shared in a transmittal letter to EPA 

dated May 29, 2020 and included in an 

attainment designation request letter.76

In addition, Maryland also stated that, 

after requesting a four-factor analysis for 

Herbert A. Wagner Unit 3 from the 

facility’s owner/operator, ‘‘the parent 

company to the H.A. Wagner Generating 

Station publicly announced a strategic 

repositioning of the facility that would 

eliminate the use of coal. The owners of 

the H.A. Wagner Generating Station 

have agreed and signed a legal consent 

order with [MDE] to cease the 

combustion of coal by 2026 . . . 

Therefore, according to the statutory 

factor of remaining useful life for this 

facility, further control is not reasonable 

. . . A four-factor analysis of H.A. 

Wagner Unit 3 similarly concludes that 

no additional controls would effectively 

control SO2 and NOX emissions at this 

facility since the remaining useful life of 

the coal-fired unit is approximately 41⁄2

years’’.77 Given the remaining useful life 

of this source, and the closure of Luke 

Paper Company, Maryland concluded 

that no further action is necessary to 

satisfy Ask 2.78

MANE–VU Ask 3 requests that, for 

‘‘each MANE–VU state that has not yet 

fully adopted an ultra-low fuel oil 

standard as requested by MANE–VU in 

2007’’, to ‘‘pursue this standard as 

expeditiously as possible and before 

2028, depending on supply 

availability’’. The Ask includes percent 

by weight standards for #2 distillate oil 

(0.0015% sulfur by weight or 15 ppm), 

#4 residual oil (0.25–0.5% sulfur by 

weight), and #6 residual oil (0.3–0.5% 

sulfur by weight). On October 3, 2014, 

Maryland adopted a rule 79 to modify 

the sulfur-in-fuel limits in accordance 

with the MANE–VU Ask. This rule 

lowered the sulfur content of all 

distillate fuel oils (#2 fuel oil and 

lighter) to 500 ppm (0.05% by mass) on 

and after July 1, 2016; this rule was 

subsequently amended 80 to lower the 

required sulfur content of all distillate 

fuel oils (#2 fuel oil and lighter) to 15 


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81See COMAR 26.11.01.01, defining ‘‘Modify’’ or 

‘‘Modification’’ to mean ‘‘any physical change in, or 

change in the operation of, a source or installation 

which causes a change in the quantity, nature or 

characteristics of emissions from the source or 

installation. However, this term excludes routine 

maintenance and routine repair, and increases in 

the hours of operation or in the production rate, 

unless these increases would be prohibited under 

any permit or approval conditions adopted by the 

Department.’’ 

82See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

83See Section 2.5.5 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

84See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

85See docket document, ‘‘MDE The 2030 

Greenhouse Gas Emissions Reduction Act (GGRA) 

Plan (February 19, 2021)’’. 

86 mde.maryland.gov/programs/air/ 

ClimateChange/Pages/Greenhouse-Gas-EmissionsReduction-Act-(GGRA)-Plan.aspx. 

87www.rggi.org/. 

88www.rggiprojectseries.org/. 

89See Section 2.5.6 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

90See Appendix 3 ‘‘MANE–VU Updated Q/d*C 

Contribution Assessment (MANE–VU, April 2016). 

91See docket documents, ‘‘MANE–VU InterRegional Ask Final 8–25–2017 (August 25, 2017)’’ 

and MANE–VU Intra-Regional Ask Final 8–25–2017 

(August 25, 2017). 

ppm (0.0015% by mass) on and after 

July 1, 2019. Maryland therefore 

concluded that it is meeting Ask 3. 

MANE–VU Ask 4 requests that states 

‘‘pursue updating permits, enforceable 

agreements, and/or rules to lock-in 

lower emission rates for SO2, NOX, and 

PM’’ at ‘‘EGUs and other large point 

emission sources larger than 250 

MMBTU per hour heat input that have 

switched to lower emitting fuels’’. Ask 

4 also states that ‘‘the permit, 

enforceable agreement, and/or rule can 

allow for suspension of the lower 

emission rate during natural gas 

curtailment’’. Maryland’s SIP submittal 

states that ‘‘EGUs and other large point 

emission sources that have switched 

operations to lower emitting fuels are 

already locked into the lower emission 

rates for NOX, SO2, and PM by permits, 

enforceable agreements, and/or rules. 

These units are required to amend their 

permits through the New Source Review 

(NSR) process if they plan to switch 

back to coal or another fuel that will 

increase emissions. A change in fuel, 

unless already allowed in the permit, 

would be a modification.’’ 81 Maryland’s 

submittal also states that ‘‘COMAR 

26.11.02.02 requires that a permit to 

construct and an approval from MDE is 

required before construction or 

modification of a source.’’ Maryland 

therefore concluded it is meeting Ask 4. 

MANE–VU Ask 5 requests that 

MANE–VU states, ‘‘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 either: ‘‘(a) Striving to meet NOX

emissions standards of no greater than 

22 ppm at 15% O2 for natural gas and 

42 ppm at 15% O2 for fuel oil but at a 

minimum meet NOX emission standards 

of no greater than 42 ppm at 15% O2 for 

natural gas and 96 ppm at 15% O2 for 

fuel oil’’, or ‘‘(b) Performing a four-factor 

analysis for reasonable installation of or 

upgrade to emission controls’’, or ‘‘(c) 

Obtaining equivalent emission 

reductions on high electric demand 

days.’’ 82 Maryland elected to perform a 

four-factor analysis for reasonable 

installation of or upgrade to emission 

controls for sources that met the 

definition of combustion turbines that 

have the potential to operate on high 

electric demand days (HEDD),83 and 

determined that it would not be 

technically feasible or cost effective to 

implement additional controls at this 

time. Maryland therefore concluded it is 

meeting Ask 5. 

MANE–VU Ask 6, the last Ask, 

requests that ‘‘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’’.84

Maryland stated in its SIP submittal that 

the electricity generation strategy in the 

state’s 2030 Greenhouse Gas Reduction 

Act (GGRA) Plan 85 86 is designed to 

achieve 100% Clean and Renewable 

Electricity by 2040 by both deploying 

energy through the existing Renewable 

Portfolio Standard (RPS) and the 

proposed Clean and Renewable Energy 

Standard (CARES), and by capping and 

reducing emissions through the 

Regional Greenhouse Gas Initiative 

(RGGI).87 88 Maryland’s RPS requires 

Maryland electric utilities to purchase 

increasingly large proportions of 

Maryland’s electricity from renewable 

energy sources like solar, wind, 

hydropower, and qualifying biomass, 

with a current RPS goal of 50% clean 

electricity by 2030 and 100% clean 

electricity by 2040. Maryland states that 

these goals rely on both renewable 

energy and additional zero- and lowcarbon electricity sources to meet that 

goal where most cost-effective, 

including Maryland solar power beyond 

current RPS requirements, new efficient 

CHP systems in Maryland buildings, 

new nuclear power, and natural gas or 

qualifying biomass power plants with 

carbon capture and storage. Maryland 

further states that, although RGGI is 

designed to reduce carbon dioxide 

emissions, other benefits in terms of 

NOX and SO2 are realized through 

energy efficiency promotion, CHP 

deployment, and additional deployment 

of renewable energy sources, including 

offshore wind power and community 

solar generation.89 Maryland therefore 

concludes that it is meeting Ask 6. 

2. The EPA’s Evaluation of Maryland’s 

Response to the Six MANE–VU Asks 

and Compliance With § 51.308(f)(2)(i) 

The EPA is proposing to find that 

Maryland has satisfied the requirements 

of 40 CFR 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 Maryland 

has satisfied the four-factor analysis 

requirement through its analysis and 

actions to address MANE–VU Ask 2 and 

Ask 5. We also propose to find that 

Maryland reasonably concluded that it 

satisfied all six Asks. 

As explained above, Maryland relied 

on MANE–VU’s technical analyses and 

framework (i.e., the Asks) to select 

sources and form the basis of its longterm 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, oil-fired 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.90 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.’’ 91 EPA proposes to find that 

Maryland 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 


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92 Id. 

93See COMAR 26.11.27, ‘‘Emission Limitations 

for Power Plants’’, also at www.epa.gov/sips-md/ 

maryland-sip-emission-limitations-power-plants. 

94See COMAR 26.11.40, ‘‘NOX Ozone Season 

Emission Caps for Non-trading Large NOX Units’’ 

also at www.epa.gov/sips-md/maryland-sip-noxozone-season-emission-caps-non-trading-large-noxunits. 

95See COMAR 26.11.27, ‘‘Emission Limitations 

for Power Plants’’, also at www.epa.gov/sips-md/ 

maryland-sip-emission-limitations-power-plants. 

96See 87 FR 66086, November 2, 2022, and 

docket documents ‘‘MDE SO2 2010 NAAQS SIP for 

Baltimore and Anne Arundel NA (January 31, 

2020)’’, and ‘‘MDE SO2 2010 NAAQS SIP for 

Baltimore and Anne Arundel NA (January 31, 

2020)—Appendix B—Consent Orders, Permits, and 

Plan Approvals’’. 

97See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

98See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

99See docket document, ‘‘EPA 2021 Regional 

Haze Clarifications Memo (July 8, 2021)’’. 

100 Id. 

101H.A. Wagner Unit 3. 

102Luke Paper Unit 001–0011–3–0018 & Unit 

001–0011–3–0019. 

103Raven Power Fort Smallwood, LLC. 

104See Appendix 19, ‘‘Herbert A. Wagner 

Generating Station Consent Order’’. 

105See Section 2.5.2 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

106See docket documents, ‘‘Verso Luke Paper— 

Luke MD Title V Permit Termination (May 7, 

2020)’’ and ‘‘Verso Luke Paper—Verso Luke Close 

Out Letter (May 8, 2020)’’. 

107See Appendix 4, ‘‘2016 MANE VU Source 

Contribution Modeling Report: CALPUFF Modeling 

of Large Electrical Generating Units and Industrial 

Sources (April 4, 2017)’’. 

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. While MANE–VU formulated the 

Asks to be ‘‘reasonable emission 

reduction strategies’’ to control 

emissions of visibility impairing 

pollutants,92 EPA believes that 

Maryland’s responses to two of the 

Asks, 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 

Maryland’s supplemental analysis and 

explanation of how it has complied with 

Ask 2 (perform four-factor analyses for 

sources with potential for ≥3.0 Mm¥1

impacts) satisfy the requirement of 40 

CFR 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 Maryland’s SIP. 40 CFR 51.308(f)(2). 

Maryland asserted that it satisfies Ask 

1 because it has SIP-approved 

regulations applicable to EGU boilers 

that include annual emission limits for 

both NOX93 94 and SO2,95 and require 

the most effective use of emission 

control technologies on a year-round 

basis. Maryland also claimed additional 

SIP-approved SO2 emission reductions 

as a result of the consent order for the 

Anne Arundel County and Baltimore 

County SO2 nonattainment area for the 

2010 SO2 NAAQS.96 As a reminder, 

MANE–VU Ask 1 requests that states 

‘‘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’’ at 

EGUs ‘‘with a nameplate capacity larger 

than or equal to 25 MW with already 

installed NOX and/or SO2 controls’’.97

Therefore, EPA finds it reasonable to 

conclude that Maryland 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.’’ 98

As an initial matter, EPA does not 

necessarily 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 4.99 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 

four-factor 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 Memo at 3.100 In 

this case, the 3.0 Mm¥1 threshold 

identified only two sources in Maryland 

(and only 22 across the entire MANE– 

VU region), indicating that they may be 

unreasonably high. Maryland selected 

all sources identified by MANE–VU as 

being above MANE–VU’s 3.0 Mm¥1

threshold for four-factor analysis. 

MANE–VU identified one unit at the 

Herbert A. Wagner Generating 

Facility,101 a coal-fired EGU, and two 

units at Verso Luke Paper Company,102

a large industrial source, as having a 

greater than 3.0 Mm¥1 visibility impact 

and thus meeting the threshold for fourfactor analyses. Maryland’s SIP 

submittal indicates that it sent a letter 

requesting a four-factor analysis to 

Herbert A. Wagner Facility’s owner/ 

operator,103 who subsequently 

announced that it would eliminate the 

use of coal at the facility. This was 

codified into a consent order between 

Maryland and the owner/operator to 

cease coal combustion at the facility by 

January 1, 2026.104 Maryland has 

requested that the entire consent order 

be incorporated into Maryland’s SIP and 

made federally enforceable upon EPA’s 

approval; 105 EPA intends to incorporate 

this consent order into the Maryland SIP 

by reference as a source-specific 

requirement upon final approval of this 

proposed rulemaking. Maryland’s 

subsequent four-factor analysis for the 

facility concluded that no further 

control was necessary. Regarding the 

Verso Luke Paper industrial source, 

Maryland stated that this facility ceased 

operations, shut down and surrendered 

their existing air permits as of May 7, 

2020.106 Informed in part by this 

development, EPA found that the area 

was monitoring air quality consistent 

with achieving the 2010 1-Hour SO2

Primary NAAQS. See 87 FR 66086, 

November 2, 2022. Maryland therefore 

concluded that no further action was 

necessary for this facility. Given that no 

other sources in Maryland met the 3.0 

Mm¥1 threshold for visibility impacts 

in MANE–VU’s analysis,107 Maryland 

concluded that it had met the 

requirements for Ask 2. 

The EPA proposes to find that 

Maryland reasonably determined it has 

satisfied Ask 2. As explained above, we 


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108See Section 2.6.1 and Table 2–12 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

109See docket document, ‘‘NPS Letter—MANE– 

VU draft Statement on source screening (April 12, 

2018)’’. 

110See docket documents, ‘‘Verso Luke Paper— 

Luke MD Title V Permit Termination (May 7, 

2020)’’ and ‘‘Verso Luke Paper—Verso Luke Close 

Out Letter (May 8, 2020)’’. 111See Section 2.6.1 and Table 2–13 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 112See docket document, ‘‘2016 Updates to the 

Assessment of Reasonable Progress for Regional 

Haze in MANE–VU Class I Areas (January 31, 

2016)’’ at 8–4. 

113 Id. see 8–7. 

114 Id. see 8–8. 

115See COMAR 03.03.05.04, ‘‘Specifications for 

No. 1 and No. 2 Fuel Oil (ASTM D–396)’’. 

do not necessarily agree that a 3.0 

Mm¥1 threshold for selecting sources 

for four-factor analysis results in a set of 

sources the evaluation of which has the 

potential to meaningfully reduce the 

state’s contribution to visibility 

impairment. MANE–VU’s threshold 

identified only two sources in Maryland 

for four-factor analysis. However, in this 

instance we propose to find that 

Maryland’s additional information and 

explanation indicates that the state has 

in fact examined a reasonable set of 

sources; Maryland chose to address 12 

of the 13 sources identified by FLMs, 

including 10 that went beyond the 

MANE–VU source selection process, 

and reasonably concluded that fourfactor analyses for its top-impacting 

sources are not necessary because the 

outcome would be that no further 

emission reductions would be 

reasonable. 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 

Maryland’s existing SIP-approved NOX

and SO2 rules that effectively control 

emissions from the largest contributing 

stationary-source sectors. Maryland’s 

submittal includes additional 

information on and analysis of 13 

Maryland facilities, which was provided 

in response a National Park Service 

(NPS) analysis that identified these 

facilities as contributing to ‘‘80% of the 

Q/d total’’ visibility impact at 

downwind NPS Class I Federal areas 

based on 2014 emissions data and 

requested that states ‘‘review and 

consider these sources for inclusion in 

their long term strategies’’.108 109

Maryland provided the NPS with 

additional information on these 13 

facilities, including facility descriptions, 

current control devices/technologies for 

NOX, SO2, and PM, current monitoring 

devices, regulations/consent orders/ 

permit conditions that limit emissions, 

and analysis and documentation of 

historical emissions to demonstrate 

control strategy effectiveness. 

Maryland also examined the 13 

facilities identified by NPS as a percent 

of their total Q/d contribution. This 

included Luke Paper Company, which 

comprised 54.71% of the Q/d total; 

Maryland stated that this facility ceased 

operations, shut down and surrendered 

their existing air permits as of May 7, 

2020.110 When combined with Brandon 

Shores Generating Station, H.A. Wagner 

Generating Station, Chalk Point 

Generating Station, C.P. Crane 

Generating Station, and Naval Support 

Facility Indian Head, all of which have 

closed, will close by 2026, or have 

switched or will switch fuels, and 

Morgantown Generating Station, which 

is considered by Maryland as effectively 

controlled through SCR, these facilities 

comprised 75.57% of the Q/d total. 

When adding the two municipal solid 

waste combustor facilities identified by 

the NPS (Wheelabrator and Montgomery 

County RRF) both of which are 

considered by Maryland as wellcontrolled, these facilities comprise 

82.22% of the Q/d total. Finally, 

Maryland also provided additional 

information on the remaining three 

sources identified by the NPS (Holcim 

Cement, Lehigh Cement, and the AES 

Warrior Run EGU).111 Therefore, EPA 

finds it reasonable to conclude that 

Maryland has satisfied Ask 2. 

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; 112 specifically, for the control 

strategy of reducing the sulfur content of 

distillate oil to 15 ppm. The analysis 

started with an assessment of the costs 

of retrofitting refineries to produce 15 

ppm heating oil in sufficient quantities 

to support implementation of the 

standard, as well as the impacts of 

requiring a reduction in sulfur content 

on consumer prices. The analysis noted 

that, as a result of previous EPA 

rulemakings to reduce the sulfur content 

of on-road and non-road-fuels to 15 

ppm, technologies are currently 

available to achieve sulfur reductions 

and many refiners are already meeting 

this standard, meaning that the capital 

investments for further reductions in the 

sulfur content of heating oil are 

expected to be relatively low compared 

to costs incurred in the past. The 

analysis also examined, by way of 

example, the impacts of New York’s 

existing 15 ppm sulfur requirements on 

heating oil prices and concluded that 

the cost associated with reducing sulfur 

was relatively small in terms of the 

absolute price of heating oil compared 

to the magnitude of volatility in crude 

oil prices. It also noted that the slight 

price premium is compensated by cost 

savings due to the benefits of lowersulfur fuels in terms of equipment life 

and maintenance and fuel stability. 

Consideration of the time necessary for 

compliance with a 15 ppm sulfur 

standard was accomplished through a 

discussion of the amount of time 

refiners had needed to comply with the 

EPA’s on-road and non-road fuel 15 

ppm requirement, and the implications 

existing refinery capacity and 

distribution infrastructure may have for 

compliance times with a 15 ppm 

heating oil standard. The analysis 

concluded that with phased-in timing 

for states that have not yet adopted a 15 

ppm heating oil standard there ‘‘appears 

to be sufficient time to allow refiners to 

add any additional heating oil capacity 

that may be required.’’ 113 The analysis 

further noted the beneficial energy and 

non-air quality environmental impacts 

of a 15 ppm sulfur heating oil 

requirement and that reducing sulfur 

content may also have a salutary impact 

on the remaining useful life of 

residential furnaces and boilers.114

EPA proposes to find that Maryland 

reasonably relied on MANE–VU’s fourfactor 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 is 

reasonable; as a reminder, MANE–VU 

Ask 3 requests that, for ‘‘each MANE– 

VU state that has not yet fully adopted 

an ultra-low fuel oil standard as 

requested by MANE–VU in 2007’’, to 

‘‘pursue this standard as expeditiously 

as possible and before 2028, depending 

on supply availability’’. Maryland’s 

ultra-low sulfur fuel oil regulations 115

are consistent with Ask 3. EPA therefore 

proposes to find that Maryland 

reasonably determined that it has 

satisfied Ask 3. 

Maryland 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, Maryland has 

asserted that EGUs and other large point 

emission sources that have switched 

operations to lower emitting fuels are 

already locked into the lower emission 

rates for NOX, SO2, and PM by permits, 


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116See COMAR 26.11.01.01, defining ‘‘Modify’’ 

or ‘‘Modification’’ to mean ‘‘any physical change in, 

or change in the operation of, a source or 

installation which causes a change in the quantity, 

nature or characteristics of emissions from the 

source or installation. However, this term excludes 

routine maintenance and routine repair, and 

increases in the hours of operation or in the 

production rate, unless these increases would be 

prohibited under any permit or approval conditions 

adopted by the Department.’’ 

117See COMAR 26.11.02.02., ‘‘General 

Provisions’’, which states that ‘‘A permit to 

construct and an approval from the Department is 

required before construction or modification of a 

source’’. 

118Peaking combustion turbine is defined for the 

purpose 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 

electric power distribution grid for commercial sale 

and that operated less than or equal to an average 

of 1,752 hours (or 20%) per year during 2014 to 

2016. 

119High 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 emissions rates of the 

generation fleet. 

120See Section 2.5.5 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

121See docket document, ‘‘EPA Combustion 

Turbine NOX Control Technology Memo (January 

2022)’’. 

122See Section 2.5.5 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

123See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

124See Appendix 7, ‘‘MANE–VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 125See Appendix 1, ‘‘Selection of States for 

MANE–VU Regional Haze Consultation (2018)— 

Final’’. 126See Appendix 20, ‘‘Public Hearing Notices, 

Comments, and Responses—Regional Haze Second 

Implementation Period Plan (2018–2028)’’. 127See COMAR 03.03.05.04, ‘‘Specifications for 

No. 1 and No. 2 Fuel Oil (ASTM D–396)’’. 

enforceable agreements and/or rules. In 

addition, modified units in Maryland 

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,116 and Maryland’s 

regulations require that an application 

to modify the permit be submitted prior 

to a change in fuel.117 As a reminder, 

MANE–VU Ask 4 requests that states 

‘‘pursue updating permits, enforceable 

agreements, and/or rules to lock-in 

lower emission rates for SO2, NOX, and 

PM’’ at ‘‘EGUs and other large point 

emission sources larger than 250 

MMBTU per hour heat input that have 

switched to lower emitting fuels’’. Ask 

4 also states that ‘‘the permit, 

enforceable agreement, and/or rule can 

allow for suspension of the lower 

emission rate during natural gas 

curtailment’’. EPA proposes to find that 

Maryland reasonably determined it has 

satisfied Ask 4. This is because the 

permitting and regulatory requirements 

outlined above, including the fact that 

sources that have switched fuel are 

generally required to revise their 

permits to reflect the change, and 

because the state rules make any 

proposed reversion difficult by 

requiring permitting and other control 

analyses, including NSR. 

Ask 5 addresses NOX emissions from 

peaking combustion turbines 118 that 

have the potential to operate on high 

electric demand days (HEDD).119

Maryland conducted a four-factor 

analysis to evaluate potential control 

options for HEDD units. For one 

potentially technically feasible control 

option, Selective Catalytic Reduction 

(SCR), Maryland estimated compliance 

costs as ranging from $6 million to $15.7 

million per unit.120 These cost estimates 

are similar to those found in EPA’s 

Combustion Turbine NOX Control 

Technology Memo published in January 

2022.121 Due to the relatively low level 

of reported annual NOX emissions from 

these units within the state (i.e., less 

than 10 tons of NOX emitted per unit 

per year), Maryland concluded that SCR 

was not an economically feasible 

control option due to the high cost of 

control. Maryland also evaluated the 

cost of water/steam injection as a 

potentially technically feasible control 

option, but found that the cost of control 

($87,906.95 per ton of NOX removed) 

was not economically feasible.122 As a 

reminder, MANE–VU Ask 5 requests 

that MANE–VU states, ‘‘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 either: ‘‘(a) Striving to meet NOX

emissions standards of no greater than 

22 ppm at 15% O2 for natural gas and 

42 ppm at 15% O2 for fuel oil but at a 

minimum meet NOX emission standards 

of no greater than 42 ppm at 15% O2 for 

natural gas and 96 ppm at 15% O2 for 

fuel oil’’, or ‘‘(b) Performing a four-factor 

analysis for reasonable installation of or 

upgrade to emission controls’’, or ‘‘(c) 

Obtaining equivalent emission 

reductions on high electric demand 

days.’’ 123 Because Maryland evaluated 

multiple technically feasible controls, 

the high cost of controls, and the 

relatively low level of reported annual 

NOX emissions from peaking 

combustion turbines with the potential 

to operate on HEDD days, EPA proposes 

to find that Maryland reasonably 

concluded that it has satisfied Ask 5. 

Finally, regarding Ask 6, Maryland 

explains the greenhouse gas initiatives 

and clean energy requirements within 

the state, including promulgation of the 

state’s 2030 Greenhouse Gas Reduction 

Act (GGRA) Plan, RPS, and 

participation in RGGI. As a reminder, 

MANE–VU Ask 6, the last Ask, requests 

that ‘‘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’’.124 The EPA is therefore 

proposing to find that Maryland 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 

that—based on Maryland’s participation 

in the MANE–VU planning process, 

how it has addressed each of the Asks, 

its supplemental information and 

explanation regarding NOX sources and 

emissions, and the EPA’s additional 

assessment of Maryland’s emissions and 

point sources—Maryland has complied 

with the requirements of 40 CFR 

51.308(f)(2)(i). Specifically, MANE–VU 

Asks 2 and 3 engage with the 

requirement that states evaluate and 

determine the emission reduction 

measures that are necessary to make 

reasonable progress by considering the 

four statutory factors. EPA is proposing 

to find Maryland’s approach to Ask 2 

reasonable because it demonstrated that 

the sources with the greatest modeled 

impacts on visibility either have 

federally-enforceable shut downs, have 

reduced their emissions so significantly 

that it is clear a four-factor analysis 

would not yield further reasonable 

emission reductions, or are subject to 

stringent emission control measures. 

Maryland’s SIP-approved control 

measures, emissions inventory 125 and 

information provided in response to 

comments 126 demonstrate 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 well 

controlled, or both. Maryland’s sulfur in 

fuel limits sets stringent limits for sulfur 

content and SO2 emissions for non-solid 

fuels.127 Therefore, it is reasonable to 

assume that selecting additional sources 

from MANE–VU’s or FLMs’ lists for 

four-factor analysis would not have 

resulted in additional emission 


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128See Appendix 5, ‘‘Inter-RPO Consultation 

Briefing Book’’; Appendix 7, ‘‘MANE–VU Regional 

Haze Consultation Report’’; Appendix 9, ‘‘National 

Park Service Letter to MANE–VU (April 2018)’’; and 

Appendix 17, ‘‘Additional MANE–VU 

documentation for establishing 3.0 Mm-1 

Threshold’’. 

129See Appendix 14, ‘‘FLM Consultation 

Initiation Letter (April 2019)’’; Appendix 15, 

‘‘National Park Service Correspondence with 

Maryland’’; Appendix 16, ‘‘US Forest Service 

Consultation Response Letter’’; and Appendix 20, 

‘‘Public Hearing Notices, Comments, and 

Responses—Regional Haze Second Implementation 

Period Plan (2018–2028)’’. 

130See Section 2.21 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

131See Section 2.8.1 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

reduction measures being determined to 

be necessary to make reasonable 

progress for the second implementation 

period. 

Additionally, MANE–VU conducted a 

four-factor analysis to support Ask 3, 

which requests that states pursue ultralow sulfur fuel oil standards to address 

SO2 emissions. Maryland has done so. 

This also contributes to satisfying 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. To the extent that MANE–VU 

and Maryland regard the measures in 

Asks 1 and 4 through 6 as being part of 

the region’s strategy for making 

reasonable progress, we propose to find 

it reasonable for Maryland to address 

these Asks by pointing to existing 

measures that satisfy each. 

3. Additional Long-Term Strategy 

Requirements 

The consultation requirements of 40 

CFR 51.308(f)(2)(ii) provides that states 

must consult with other states that are 

reasonably anticipated to contribute to 

visibility impairment in a Class I area to 

develop coordinate 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. 

Maryland participated in and 

provided documentation of the MANE– 

VU intra- and inter-RPO consultation 

processes and addressed the MANE–VU 

Asks by providing information on the 

measures it has in place that satisfy each 

Ask.128 129 MANE–VU also documented 

disagreements that occurred during 

consultation. MANE–VU noted in their 

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. Upwind 

states also suggested that MANE–VU 

states adopt the 2021 timeline for 

regional haze SIP submissions for the 

second planning period. MANE–VU 

agreed with the reasons the comments 

provided, such as collaboration with 

data and planning efforts. However, 

MANE–VU disagreed that the 2018 

timeline would prohibit collaboration. 

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. 

In sum, Maryland participated in the 

MANE–VU intra- and inter-RPO 

consultation and satisfied the MANE– 

VU Asks, satisfying 40 CFR 

51.308(f)(2)(ii)(A) and (B). Maryland 

satisfied 40 CFR 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 both 

MANE–VU’s and Maryland’s responses 

to states’ comments on the SIP 

submission and various technical 

analyses therein, we propose to 

determine that Maryland has satisfied 

the consultation requirements of 40 CFR 

51.308(f)(2)(ii). 

The documentation requirement of 40 

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

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, Maryland 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 Maryland 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. Maryland 

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 

Maryland satisfies the documentation 

requirements of 40 CFR 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. Maryland’s SIP submission 

included 2017 NEI emission data for 

NOX, SO2, PM, and NH3 and 2017 Air 

Markets Program Data (AMPD) 

emissions for NOX and SO2. Maryland’s 

SIP submission also included 2019 

AMPD for NOX and SO2.130 Based on 

Maryland’s consideration and analysis 

of the 2017 and 2019 emission data in 

their SIP submittal and supplemental 

documentation, the EPA proposes to 

find that Maryland has satisfied the 

emissions information requirement in 

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

We also propose to find that Maryland 

reasonably considered the five 

additional factors in 40 CFR 

51.308(f)(2)(iv) in developing its longterm strategy. Pursuant to 40 CFR 

51.308(f)(2)(iv)(A), Maryland 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. 

Maryland included in their SIP 

comprehensive lists of control measures 

with their effective dates, pollutants 

addressed, and corresponding Code of 

Maryland Regulations provisions.131


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132COMAR 26.11.06.03. ‘‘Particulate Matter’’, 

subsection D; State Effective Date November 11, 

2002 (29:22 Md. R. 1724) (68 FR 46487). 

133COMAR 11.14. ‘‘MOTOR VEHICLE 

ADMINISTRATION—VEHICLE INSPECTIONS’’, 

.01, .06, and .08. 

134COMAR. 11.21.02. ‘‘Diesel Vehicle Emissions 

Control Program’’; State Effective Date July 10, 2000 

(27:13 Md. R. 1212). 

135Md. Code, Transp. § 23–401 through 23–404. 

136Md. Code, Transp. § 21–1101. 

137The authority to address General Conformity 

is set forth in Section 176(c) of the Clean Air Act 

and the requirements to demonstrate conformity are 

found in the EPA’s implementing regulation (40 

CFR part 93, subpart B—Determining Conformity of 

General Federal Actions to State or Federal 

Implementation Plans). 

138COMAR 26.11.26. ‘‘Conformity’’; State 

Effective Date June 5, 1995 (22:11 Md. R. 825). 

139See ‘‘Table 2–14: Units Retired in the Regional 

Haze Inventories’’ of the MD Regional Haze SIP for 

the Second Implementation Period 2018—2028 

(February 8, 2022). 

140See Figures 2–7 through 2–10 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

141See docket document, ‘‘TD MANE–VU 2000– 

19 RH METRICS COMPARISON PLOTS 12–19– 

20.xlsx’’. 

142See docket document, ‘‘TD MANE–VU 2000– 

19 RHII & III Metrics Trends Plots 12–19–20.xlsx’’. 

143See docket document, ‘‘MANE–VU Trends 

2004–17 Report 2nd SIP Metrics—December 2018 

Update—Final’’. 

Maryland’s consideration of measures 

to mitigate the impacts of construction 

activities as required by 40 CFR 

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

2.8.2 of its SIP submission, a list of 

measures that Maryland has 

implemented to mitigate the impacts 

from such activities. Maryland has 

implemented standards that reduce 

fugitive dust emissions from 

construction,132 rules to address exhaust 

emissions,133 134 135 including rules to 

limit the idling of vehicles and 

equipment and rules to reduce 

allowable smoke from on-road diesel 

engines,136 and general conformity 

rules.137 138

Pursuant to 40 CFR 51.308(f)(2)(iv)(C), 

source retirements and replacement 

schedules are addressed in section 2.8.3 

of Maryland’s 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 

identified in Table 2–14.139 No nonEGU point source retirements in 

Maryland were considered when 

developing the 2028 emissions 

projections. 

In considering smoke management as 

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

Maryland explained, in section 2.8.4 of 

its submission, that emissions from 

agricultural and prescribed burning for 

forestry smoke management within the 

state are low; PM2.5 statewide emissions 

from prescribed fires were 1,349.18 tons 

(4.13% of Maryland’s overall PM2.5

emissions inventory) and emissions 

from agricultural burning were 1.5 tons 

(<1% of Maryland’s overall PM2.5

emissions inventory). Maryland 

therefore concludes that it is unlikely 

that fires in Maryland for agricultural or 

forestry management cause impacts on 

visibility in the MANE–VU and nearby 

Class I areas, including Shenandoah, 

Dolly Sods, Otter Creek, and James 

River Face. Maryland states that Smoke 

Management Plans is a required element 

of a SIP only if it is required to make 

reasonable progress, and that although 

Maryland does not need an official 

Smoke Management Plan, it has the 

legal authority to manage burning 

through a formal permitting system if 

necessary. 

Maryland considered the anticipated 

net effect of projected changes in 

emissions as required by 40 CFR 

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

section 2.8.5 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. Maryland presented 

the differences between the base and 

control cases on the 20% most impaired 

and 20% clearest days for each MANE– 

VU Class I area.140

Because Maryland has reasonably 

considered each of the five additional 

factors the EPA proposes to find that 

Maryland 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. Section 51.308(f)(3)(i) 

requires a state in which a Class I area 

is located to establish RPGs—one each 

for the most impaired and clearest 

days—reflecting the visibility 

conditions that will be achieved at the 

end of the implementation period as a 

result of the emission limitations, 

compliance schedules and other 

measures required under paragraph 

(f)(2) to be in states’ long-term strategies, 

as well as implementation of other CAA 

requirements. The long-term strategies 

as reflected by the RPGs must provide 

for an improvement in visibility on the 

most impaired days relative to the 

baseline period and ensure no 

degradation on the clearest days relative 

to the baseline period. Section 

51.308(f)(3)(ii) applies in circumstances 

in which a Class I area’s RPG for the 

most impaired days represents a slower 

rate of visibility improvement than the 

uniform rate of progress calculated 

under 40 CFR 51.308(f)(1)(vi). Under 40 

CFR 51.308(f)(3)(ii)(A), if the state in 

which a mandatory Class I area is 

located establishes an RPG for the most 

impaired days that provides for a slower 

rate of visibility improvement than the 

URP, the state must demonstrate that 

there are no additional emission 

reduction measures for anthropogenic 

sources or groups of sources in the state 

that would be reasonable to include in 

its long-term strategy. 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. Because Maryland 

has no Class I areas within its borders, 

it is subject only to 40 CFR 

51.308(f)(3)(ii)(B). 

Under 40 CFR 51.308(f)(3)(ii)(B), a 

state that contains sources that are 

reasonably anticipated to contribute to 

visibility impairment in a Class I area in 

another state for which a demonstration 

by the other state is required under 40 

CFR 51.308(f)(3)(ii)(B) must demonstrate 

that there are no additional emission 

reduction measures that would be 

reasonable to include in its long-term 

strategy. Maryland’s SIP submittal 

included MANE–VU’s glidepath checks 

for nearby downwind Class I areas,141 142

which show that the RPG for the 20 

percent most anthropogenically 

impaired days for the affected 

downwind Class I areas (Acadia, 

Brigantine, Great Gulf, Lye Brook, 

Moosehorn, Dolly Sods and 

Shenandoah) are not above the URP 

glidepath, and that the RPG for the 20 

percent clearest days shows no 

degradation. In addition, the modeled 

MANE–VU 2028 visibility projections at 

nearby Class I areas 143 show that the 

base case 2028 projections for the most 

impaired days at these areas are below 

the respective 2028 points on the URPs. 

Therefore, we propose it is reasonable to 

assume that the demonstration 

requirement under 40 CFR 

51.308(f)(3)(ii)(B) as it pertains to these 

areas will not be triggered. 

The EPA proposes to determine that 

Maryland has satisfied the applicable 

requirements of 40 CFR 51.308(f)(3) 

relating to RPGs. 


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144See Section 2.16 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

145AMPD sources are facilities that participate in 

EPA’s emission trading programs. The majority of 

AMPD sources are electric generating units (EGUs). 

146See Appendix 11 ‘‘Ozone Transport 

Commission/Mid-Atlantic Northeastern Visibility 

Union 2011 Based Modeling Platform Support 

Document—October 2018 Update (October 2018)’’. 

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. A main requirement of this 

subsection is for states with Class I areas 

to submit monitoring strategies for 

measuring, characterizing, and reporting 

on visibility impairment. Compliance 

with this requirement may be met 

through participation in the Interagency 

Monitoring of Protected Visual 

Environments (IMPROVE) network. 

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

provide for the establishment of any 

additional monitoring sites or 

equipment needed to assess whether 

reasonable progress goals to address 

regional haze for all mandatory Class I 

Federal areas within the state are being 

achieved. Section 51.308(f)(6)(ii) 

requires SIPs to provide for procedures 

by which monitoring data and other 

information are used in determining the 

contribution of emissions from within 

the state to regional haze visibility 

impairment at mandatory Class I 

Federal areas both within and outside 

the state. Because Maryland does not 

have any Class I Federal areas located 

within its borders, Section 

51.308(f)(6)(i) and (ii) do not apply. 

Section 51.308(f)(6)(iii) requires states 

with no Class I areas to include 

procedures by which monitoring data 

and other information are used in 

determining the contribution of 

emissions from within the State to 

regional haze visibility impairment at 

Class I areas in other states. States with 

Class I areas must establish a monitoring 

program and report data to EPA that is 

representative of visibility at the Class I 

Federal areas. The IMPROVE network 

meets this requirement. Maryland stated 

that, as a participant in MANE–VU, it 

reviewed information about the 

chemical composition of baseline 

monitoring data at Class I Federal areas 

in and near MANE–VU in order to 

understand the sources of haze causing 

pollutants. Maryland commits to 

continuing support of ongoing visibility 

monitoring in Class I Federal areas, 

agrees that the IMPROVE network is an 

appropriate monitoring network to track 

regional haze progress, and commits to 

working with neighboring states and 

FLMs to meet the goals of the IMPROVE 

program. Maryland also commits to 

using monitoring data and procedures 

consistent with US EPA guidance to 

review progress and trends in visibility 

at Class I Federal areas that may be 

affected by emissions from Maryland, 

both for comprehensive periodic 

revisions of this implementation plan 

and for periodic reports describing 

progress towards the reasonable 

progress goals for those areas.144

Section 51.308(f)(6)(iv) requires the 

SIP to provide for the reporting of all 

visibility monitoring data to the 

Administrator at least annually for each 

Class I area in the state. As noted above, 

Maryland does not have any Class I 

Federal areas located within its borders, 

therefore this requirement does not 

apply. 

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. Maryland 

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 statewide inventory of pollutants that are 

reasonably anticipated to cause or 

contribute to visibility impairment. 

Section 2.21 of Maryland’s 

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.145 Maryland 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. Maryland also provided 

a summary of SO2 and NOX emissions 

for AMPD sources for the years of 2016, 

2017, 2018, and 2019. 

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. Maryland 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 on-the-books 

controls and a 2028 control case that 

considers implementation of the 

MANE–VU Asks.146

EPA proposes to find that Maryland 

has met the requirements of 40 CFR 

51.308(f)(6) as described above, 

including through its continued 

participation in the IMPROVE network 

and the MANE–VU RPO and its ongoing compliance with the AERR, and 

that no further elements are necessary at 

this time for Maryland to assess and 

report on visibility pursuant to 40 CFR 

51.308(f)(6)(vi). 

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 each Class I area within the 

state and each Class I area outside the 

state that may be affected by emissions 

from within that state. Section 

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 


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58200 Federal Register / Vol. 88, No. 164 / Friday, August 25, 2023 / Proposed Rules 

147COMAR 26.11.30—Control of Portland 

Cement Manufacturing Plants. Effective date: July 

20, 2015 (42:Md. R. 884). www.dsd.state.md.us/ 

comar/SubtitleSearch.aspx?search=26.11.30.* 

Approved by EPA March 28, 2018, 83 FR 13192 

148See Section 2.21.1 and Table 2–20 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018—2028 (February 8, 2022) 

149See Section 2.21.3 and Table 2–28 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

150See ‘‘Statement of the Mid-Atlantic/Northeast 

Visibility Union (MANE–VU) Concerning a Course 

of Action within MANE–VU Toward Assuring 

Reasonable Progress’’ in the docket. 

151See Section 2.21.2 and Table 2–25 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

152See Section 2.21.4 and Table 2–33 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

153See Section 2.21 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

154See docket document, ‘‘MANE-VU Trends 

2004–17 Report 2nd SIP Metrics - December 2018 

Update—Final’’. 

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, 40 CFR 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 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. 

Maryland’s submission describes the 

status of measures of the long-term 

strategy from the first implementation 

period. As a member of MANE–VU, 

Maryland 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. Maryland 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 sulfur dioxide (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. Maryland describes in 

Section 2.18 of its submittal control 

measures put in place during the first 

implementation period to help reduce 

the emissions of visibility-impairing 

pollutants, including NOX and SO2. 

This includes the Maryland Healthy Air 

Act (HAA), which covered Maryland 

emission sources named in MANE–VU’s 

‘‘167 Stacks’’; the HAA was 

implemented in 2010 and further 

tightened SO2 emission control 

requirements in 2013, resulting in 

significant reductions in visibilityimpairing pollutants throughout the 

state that exceeded MANE–VU target 

goals. Maryland also described its 

implementation of low sulfur fuel oil 

standards for the state, and the status of 

the remaining emissions sources in the 

state subject to BART requirements, 

which included emission reductions for 

Portland cement plants to satisfy 

Reasonably Available Control 

Technology (RACT) requirements for 

ozone.147

EPA proposes to find that Maryland 

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 strategy from 

the first implementation period, as well 

as the status of their implementation 

and the emission reductions achieved 

through such implementation. 

Section 51.308(g)(3) requires states to 

assess Reasonable Progress Goals, 

including current visibility conditions 

and changes, for any Class I areas within 

the state. As described above, Maryland 

does not have any Class I areas within 

its borders, therefore 40 CFR 

51.308(g)(3) does not apply. 

Pursuant to 40 CFR 51.308(g)(4), in 

Section 2.21 of their submittal, 

Maryland provided a summary of 

emissions of NOX, SO2, PM10, PM2.5, 

VOCs, and NH3 from all sources and 

activities, including from point, 

nonpoint, non-road mobile, and on-road 

mobile sources, for the time period from 

2002 to 2017. Maryland also included 

AMPD data for SO2 and NOX emissions 

for 2016, 2017, 2018, and 2019 in their 

submission. 

The reductions achieved through 

Maryland emission control measures are 

seen in the emissions inventory. Based 

on Maryland’s SIP submittal, NOX

emissions have continuously declined 

in Maryland from 2002 through 2017, 

especially in the point, nonroad and 

onroad mobile sectors. During that 

period, onroad sources contributed 

almost half of the emissions at 47%, 

followed by point sources at 27%. 

Nonroad sources contributed 13% and 

area sources contributed 13%. Table 2– 

20 of Maryland’s SIP submittal also 

shows additional NOX emissions data 

from 2016 to 2019 for Maryland’s point 

sources that report to EPA’s AMPD. 

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.148

Emissions of SO2 have shown a 

significant decline in Maryland from 

2002 to 2017 across multiple sectors; see 

Section 2.21.3 and Table 2–28 of 

Maryland’s SIP submittal.149 Reductions 

in point emissions are primarily due to 

the acid rain program, Maryland power 

plant consent decrees and regulations 

including the Maryland Health Air Act, 

and Federal and State low sulfur fuel 

regulations. Additionally, some of these 

decreases may be attributable to the 

MANE–VU low sulfur fuel strategy and 

the 90% or greater reduction in SO2

emissions at 167 EGU stacks, both 

inside and outside of MANE–VU, 

requested in the ‘‘Non-MANE–VU Ask’’ 

for states within MANE–VU for the first 

regional haze planning period.150

Emissions of PM10 have steadily 

decreased in Maryland from 2002 to 

2017, particularly in the point and 

nonroad sectors; see Section 2.21.2 and 

Table 2–25 of Maryland’s SIP 

submittal.151 The variations in the 

onroad sector are likely due to changes 

in emission inventory calculation 

methodologies, which resulted in higher 

particulate matter estimates in the other 

years than in 2002. The large variation 

in emissions in the nonpoint category is 

likely due to changes in calculation 

methodologies for residential wood 

burning and fugitive dust categories, 

which have varied significantly. 

Emissions of ammonia (NH3) have 

shown declines in Maryland from 2002 

to 2017; see Section 2.21.4 and Table 2– 

33 of Maryland’s SIP submittal.152

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 2014 are due to 

reporting, grouping and methodology 

changes. While ammonia emissions 

grew slightly between the 2002 and 

2008 emission inventories, ammonia 

emissions have decreased from 2011 to 

2017. 

The EPA is proposing to find that 

Maryland has satisfied the requirements 

of 40 CFR 51.308(g)(4) by providing 

emissions information for NOX, SO2, 

PM10, PM2.5, VOCs, and NH3 broken 

down by type of source. 

Maryland uses the emissions trend 

data in the SIP submission 153 and 

supporting MANE-VU information 154

provided to support the assessment that 


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Federal Register / Vol. 88, No. 164 / Friday, August 25, 2023 / Proposed Rules 58201 

155See Section 2.16 of the MD Regional Haze SIP 

for the Second Implementation Period 2018–2028 

(February 8, 2022). 

156See Appendix 7, ‘‘MANE-VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

157See Appendix 7, ‘‘MANE-VU Regional Haze 

Consultation Report (July 27, 2018),’’ and Appendix 

9, ‘‘National Park Service Letter to MANE-VU (April 

2018)’’ of the MD Regional Haze SIP for the Second 

Implementation Period 2018–2028 (February 8, 

2022). 

158See Appendix 7, ‘‘MANE-VU Regional Haze 

Consultation Report (July 27, 2018),’’ of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

159See Appendix 15, ‘‘National Park Service 

Correspondence with Maryland’’, of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

160See Section 2.6 and Appendix 20 of the MD 

Regional Haze SIP for the Second Implementation 

Period 2018–2028 (February 8, 2022). 

161See Appendix 14, Appendix 15, Appendix 16, 

and Appendix 20 of the MD Regional Haze SIP for 

the Second Implementation Period 2018–2028 

(February 8, 2022), and docket documents, 

‘‘National Park Service Comments’’; ‘‘State of 

Maryland Mail—Forest Service’’; ‘‘USFS MD RH 

SIP Comment Letter’’; ‘‘USFS MD RH SIP Comment 

Enclosure’’ 

162See Section 2.17, ‘‘Progress Report 

Requirements’’, of the MD Regional Haze SIP for the 

Second Implementation Period 2018–2028 

(February 8, 2022). 

anthropogenic haze-causing pollutant 

emissions in Maryland have decreased 

during the reporting period and that 

changes in emissions have not limited 

or impeded progress in reducing 

pollutant emissions and improving 

visibility, Maryland 2017 emission 

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

VOCs, and NH3 were lower than their 

2014 emission inventories for those 

same pollutants emissions.155 The EPA 

is proposing to find that Maryland has 

met the requirements of 40 CFR 

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, 40 

CFR 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, Regardless, 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 provides two 

substantive topics on which FLMs must 

be provided an opportunity to discuss 

with states: assessment of visibility 

impairment in any Class I area and 

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 

meetings. Maryland participated in 

these consultation meetings and 

calls.156

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.157 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 relative to 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 12 facilities in Maryland in 

this letter.158 Maryland included the 

NPS initial letter in their proposed SIP. 

In a subsequent letter dated October 22, 

2018, NPS identified 13 facilities for 

which more control information was 

desired.159 Maryland detailed the 

emission controls and updates to these 

facilities in its SIP submittal to address 

the NPS’s request for more 

information.160

On September 2, 2021, Maryland 

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).161 Maryland received 

comments from the Forest Service on 

October 28, 2021, and from the National 

Park Service on October 29, 2021. 

Maryland responded to the FLM 

comments and included the responses 

in Appendix 20 of their submission to 

EPA, in accordance with 40 CFR 

51.308(i)(3). Notices of the proposed 

SIP, availability and the public hearing 

were published on MDE’s website and 

in the Maryland Register, and interested 

parties were emailed the notice, along 

with air quality contacts from other 

states, air quality regional organizations 

and the EPA. A public hearing on the 

proposed SIP revision was held on 

January 4, 2022. Written comments 

relevant to the proposal were accepted 

until the close of business January 4, 

2022. 

For the reasons stated above, the EPA 

proposes to find that Maryland 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. 

Maryland’s February 8, 2022 SIP 

submission includes a commitment to 

revise and submit a regional haze SIP by 

July 31, 2028, and every ten years 

thereafter. The state’s commitment 

includes submitting periodic progress 

reports in accordance with 40 CFR 

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 40 CFR 

51.308(g).162

V. Proposed Action 

EPA is proposing to approve 

Maryland’s February 8, 2022 SIP 

submission, as satisfying the regional 

haze requirements for the second 

implementation period contained in 40 

CFR 51.308(f). 

VI. Statutory and Executive Order 

Reviews 

Under the CAA, the Administrator is 

required to approve a SIP submission 


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58202 Federal Register / Vol. 88, No. 164 / Friday, August 25, 2023 / Proposed Rules 

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); 

• 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; and 

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 Maryland Department of 

the Environment 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. Due to the nature of the action 

being taken here, this action 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 

action, pertaining to Maryland 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). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

Reference, Nitrogen dioxide, Ozone, 

Particulate matter, Sulfur oxides. 

Adam Ortiz, 

Regional Administrator, Region III. 

[FR Doc. 2023–18278 Filed 8–24–23; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R02–OAR–2022–0648, FRL–11358– 

01–R2] 

Approval and Promulgation of 

Implementation Plans; New York; 

Elements of the 2008 and 2015 Ozone 

National Air Quality Standards 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to approve a 

State Implementation Plan (SIP) 

revision submitted by the State of New 

York for purposes of certifying and 

meeting the requirements for 

Reasonably Available Control 

Technology (RACT) for the Serious 

classification of the 2008 and Moderate 

classification of the 2015 8-hour Ozone 

National Ambient Air Quality Standards 

(NAAQS). The EPA is also proposing to 

approve that this SIP revision fulfills 

SIP requirements pertaining to the 

Ozone Transport Region (OTR) for the 

2015 Ozone NAAQS. The EPA is 

proposing to approve the demonstration 

portion of the comprehensive SIP 

revision submitted by New York that 

certify that the State has satisfied the 

requirements for an Ozone 

nonattainment new source review 

program, certify that the State has 

satisfied the requirements for a 

nonattainment emission inventory, and 

certify that the State has satisfied the 

requirements for clean fuels for fleets. 

The EPA is also proposing to approve 

New York’s reasonable further progress 

plans and motor vehicle emissions 

budgets for both the Moderate and 

Serious classifications of the 2008 

Ozone NAAQS. 

DATES: Written comments must be 

received on or before September 25, 

2023. 

ADDRESSES: Submit your comments, 

identified by Docket ID Number EPA– 

R02–OAR–2022–0648 at https://

www.regulations.gov. Follow the online 

instructions for submitting comments. 

Once submitted, comments cannot be 

edited or removed from Regulations.gov. 

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, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www2.epa.gov/dockets/ 

commenting-epa-dockets. 


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