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 6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 51 and 52

[EPA-HQ-OAR-2015-0531; FRL-9935-27-OAR]

RIN 2060-AS55 

Protection of Visibility: Amendments to Requirements for State Plans 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection Agency (EPA) is proposing amendments to 

requirements under the Clean Air Act (CAA) for state plans for protection of visibility in 

mandatory Class I federal areas (Class I areas) in order to continue steady environmental 

progress while addressing administrative aspects of the program. The EPA amendments would 

clarify the relationship between long-term strategies and reasonable progress goals in state plans, 

and the long-term strategy obligation of all states. The amendments would also change the way 

in which some days during each year are to be selected for purposes of tracking progress towards 

natural visibility conditions to account for events such as wildfires; change aspects of the 

requirements for the content of progress reports; update, simplify and extend to all states the 

provisions for reasonably attributable visibility impairment and revoke existing federal 

implementation plans (FIPs) that require the EPA to assess and address any existing reasonably 

attributable visibility impairment situations in some states; and add a requirement for states to 

consult with Federal Land Managers (FLMs) earlier in the development of state plans. The EPA 

also proposes to address administrative aspects of the program by making a one-time adjustment 
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to the due date for the next state implementation plans (SIPs), revising the due dates for progress 

reports and removing the requirement for progress reports to be SIP revisions. 

DATES: Comments. Written comments on this proposal must be received on or before 

[INSERT DATE 60 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL 

REGISTER]. Public hearing. The EPA is holding a public hearing concerning the proposed rule 

on April 26, 2016[insert date], in Washington, D.C. The last day to pre-register to speak at the 

hearing is April 22, 2016[insert date]. Please refer to SUPPLEMENTARY INFORMATION

for additional information on submitting comments and the public hearing. Information 

collection request. Under the Paperwork Reduction Act (PRA), comments on the information 

collection provisions are best assured of having full effect if the Office of Management and 

Budget (OMB) receives a copy of your comments on or before [INSERT DATE 30 DAYS 

AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].

ADDRESSES: Comments: Submit your comments, identified by Docket ID No. EPA-HQOAR-2015-0531, at http://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 
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making effective comments, please visit http://www2.epa.gov/dockets/comments.html. Public 

hearing: A public hearing will be held at William Jefferson Clinton East building (WJC East),

room 1153[add location], in Washington, D.C. Identification is required. If your driver’s license 

is issued by American Samoa, Illinois or Missouri or Minnesota, you must present an additional 

form of identification to enter. Enhanced driver’s licenses from Minnesota and Washington are 

acceptable. Please refer to SUPPLEMENTARY INFORMATION for additional information 

on the public hearing and location requirements. 

FOR FURTHER INFORMATION CONTACT: For general information on this proposed rule 

and ICR, contact Mr. Christopher Werner, Office of Air Quality Planning and Standards, U.S. 

Environmental Protection Agency, by phone at (919) 541-5133 or by email at 

werner.christopher@epa.gov; or Ms. Rhea Jones, Office of Air Quality Planning and Standards, 

U.S. Environmental Protection Agency, by phone at (919) 541-2940 or by email at 

jones.rhea@epa.gov. For information on the public hearing or to register to speak at the hearing, 

contact Ms. Pamela Long, Office of Air Quality Planning and Standards, U.S. Environmental 

Protection Agency, by phone at (919) 541-0641 or by email at long.pam@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. General Information 

A. Preamble Glossary of Terms and Acronyms 

 The following are abbreviations of terms used in this document. 

AQRV Air quality related value 

BART Best available retrofit technology 

bext Light extinction 

CAA Clean Air Act 

CFR Code of Federal Regulations 

EGU Electric generating unit 

EPA Environmental Protection Agency 
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FIP Federal implementation plan 

FLM or FLMs Federal Land Manager or Managers 

ICR Information collection request 

IMPROVE Interagency monitoring of protected visual environments 

NAAQS National ambient air quality standards 

NOx Nitrogen oxides 

OMB Office of Management and Budget 

PM Particulate matter 

PM2.5 Particulate matter equal to or less than 2.5 microns in diameter (fine 

particulate matter) 

PM10 Particulate matter equal to or less than 10 microns in diameter 

PRA Paperwork Reduction Act 

PSD Prevention of significant deterioration 

RPO Regional planning organization 

SIP State implementation plan 

SO2 Sulfur dioxide 

TAR Tribal Authority Rule 

URP Uniform rate of progress 

B. Does this action apply to me? 

Entities potentially affected directly by this proposed rule include state, local and tribal1

governments, as well as FLMs responsible for protection of visibility in mandatory Class I areas. 

Entities potentially affected indirectly by this proposed rule include owners and operators of 

sources that emit particulate matter equal to or less than 10 microns in diameter (PM10), 

particulate matter equal to or less than 2.5 microns in diameter (PM2.5 or fine PM), sulfur dioxide 

(SO2), oxides of nitrogen (NOx), volatile organic compounds and other pollutants that may cause 

 

1

 The Regional Haze Rule may apply, as appropriate under the Tribal Authority Rule (TAR) in 

40 CFR part 49, to an Indian tribe that receives a determination of eligibility for treatment as a 

state for purposes of administering a tribal visibility protection program under section 169A of 

the CAA. No tribe has applied for such status, and so at present the EPA is responsible for 

implementation of the Regional Haze Rule in areas of tribal authority. This responsibility 

includes, but is not limited to, implementation of the reasonable progress requirements of 40 

CFR 51.308(f) in instances where potentially affected sources are located on tribal land, as 

necessary or appropriate. The proposed rule changes may impact the development and 

approvability of tribal implementation plans that tribes may wish to develop in the future. We 

encourage states to provide outreach and engage in discussions with tribes about their regional 

haze SIPs as they are being developed. 
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or contribute to visibility impairment. Others potentially affected indirectly by this proposed rule 

include members of the general public who live, work or recreate in mandatory Class I areas 

affected by visibility impairment. Because emission sources that contribute to visibility 

impairment in Class I areas also may contribute to air pollution in other areas, members of the 

general public may also be affected by this proposed rulemaking. 

C. What should I consider as I prepare my comments for the EPA? 

When submitting comments, remember to: 

• Identify the rulemaking docket by docket number and other identifying 

information (subject heading, Federal Register date and page number). 

• Follow directions. The proposed rule may ask you to respond to specific questions 

or organize comments by referencing a Code of Federal Regulations (CFR) part 

or section number. 

• Explain why you agree or disagree, suggest alternatives and substitute language 

for your requested changes. 

• Describe any assumptions and provide any technical information and/or data that 

you used to support your comment. 

• If you estimate potential costs or burdens, explain how you arrived at your 

estimate in sufficient detail to allow for it to be reproduced. 

• Provide specific examples to illustrate your concerns wherever possible, and 

suggest alternatives. 

• Explain your views as clearly as possible, avoiding the use of profanity or 

personal threats. 

• Make sure to submit your comments by the comment period deadline identified. 
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 Please note that this is a narrow proposed rulemaking. Please focus your comments on 

only those sections of the CFR affected by our proposed changes. 

D. What information should I know about the public hearing? 

The April 26, 2016,[insert date] public hearing will be held to accept oral comments on 

this proposed rulemaking. The hearing will be held at the U.S. Environmental Protection 

Agency, William Jefferson Clinton East Building (WJC East), Room 1153, 1201 Constitution 

Avenue, NW, Washington, D.C.[insert location]. It will convene at [EPA to insert time] 9:00 

a.m. and continue until the earlier of [EPA to insert time] 5:00 p.m. or 1 hour after the last 

registered speaker has spoken. We have scheduled a lunch break from [EPA to insert 

time]12:00 to 1:00 p.m. People interested in presenting oral testimony should contact Ms. 

Pamela Long, Air Quality Planning Division, Office of Air Quality Planning and Standards, U.S. 

Environmental Protection Agency, Research Triangle Park, NC 27711, telephone (919) 541-

0641, fax number (919) 541-5509, email address long.pam@epa.gov, at least 2 days in advance 

of the public hearing (see DATES). Additionally, requests to speak will be taken the day of the 

hearing at the hearing registration desk, although preferences on speaking times may not be able 

to be fulfilled. Depending on the flow of the day, times may fluctuate. People interested in 

attending the public hearing should also call Ms. Long to verify the time, date and location of the 

hearing. While the EPA expects the hearing to go forward as set forth, we ask that you monitor 

our website at http://www.epa.gov/visibility http://www.epa.gov/XXXXXX.html or contact Ms. 

Pamela Long to determine if there are any updates to the information on the hearing. 

Oral testimony will be limited to 5 minutes for each commenter. The EPA encourages 

commenters to provide the EPA with a copy of their oral testimony electronically (via email) 

before the hearing and in hard copy form at the hearing. 
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The EPA may ask clarifying questions during the oral presentations, but will not respond 

to the presentations at that time. Written statements and supporting information submitted during 

the comment period will be considered with the same weight as oral comments and supporting 

information presented at the public hearing. Verbatim transcripts of the hearing and written 

statements will be included in the docket for the rulemaking. 

Because this hearing is being held at United States (U.S.) government facilities, 

individuals planning to attend the hearing should be prepared to show valid picture identification 

to the security staff in order to gain access to the meeting room. Please note that the REAL ID 

Act, passed by Congress in 2005, established new requirements for entering federal facilities. If 

your driver’s license is issued by American Samoa, Illinois or MinnesotaMissouri, you must 

present an additional form of identification to enter the federal building. Enhanced driver’s 

licenses from Minnesota and Washington are acceptable. Acceptable alternative forms of 

identification include: federal employee badges, passports, enhanced driver’s licenses, and 

military identification cards. For additional information for the status of your state regarding 

REAL ID, go to http://www.dhs.gov/real-id-enforcement-brief. In addition, you will need to 

obtain a property pass for any personal belongings you bring with you. Upon leaving the 

building, you will be required to return this property pass to the security desk. No large signs will 

be allowed in the building, cameras may only be used outside of the building, and 

demonstrations will not be allowed on federal property for security reasons. 

Attendees may be asked to go through metal detectors. To help facilitate this process, 

please be advised that you will be asked to remove all items from all pockets and place them in 

provided bins for screening; remove laptops, phones, or other electronic devices from their 

carrying case and place in provided bins for screening; avoid shoes with metal shanks, toe 
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guards, or supports as a part of their construction; remove any metal belts, metal belt buckles, 

large jewelry, watches, and follow the instructions of the guard if identified for secondary 

screening. Additionally, no weapons or drugs or drug paraphernalia will be allowed in the 

building. We recommend that you arrive 20 minutes in advance of your speaking time to allow 

time to go through security and to check in with the registration desk. 

E. Where can I obtain a copy of this document and other related information? 

In addition to being available in the docket, an electronic copy of this Federal Register

document will be posted at http://www.epa.gov/visibilityhttp://www.epa.gov/XXXXXX.html. 

F. How is this Federal Register document organized?

The information presented in this document is organized as follows: 

I. General Information 

 A. Preamble Glossary of Terms and Acronyms 

B. Does this action apply to me? 

C. What should I consider as I prepare my comments for the EPA? 

D. What information should I know about the public hearing? 

E. Where can I obtain a copy of this document and other related information? 

F. How is this Federal Register document organized? 

II. What action is the EPA proposing to take? 

III. What is the background for the EPA’s proposed action? 

A. Reasonably Attributable Visibility Impairment 

B. Regional Haze 

1. Requirements of the 1990 CAA Amendments and the EPA’s Regional Haze 

Rule 

2. Roles of Agencies in Addressing Regional Haze 

3. Requirements for the Regional Haze SIPs 

4. Requirements for the Regional Haze Progress Reports 

5. Tribes and Regional Haze 

C. Air Permitting 

IV. Proposed Rule Changes 

A. Clarifications to Reflect the EPA’s Long-Standing Interpretation of the Relationship 

Between Long-Term Strategies and Reasonable Progress Goals 

B. Other Clarifications and Changes to Requirements for Periodic Comprehensive 

Revisions of Implementation Plans 

C. Changes to Definitions and Terminology Related to How Days Are Selected for 

Tracking Progress 
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D. Impacts on Visibility from Anthropogenic Sources Outside the U.S.

D.E. Impacts on Visibility from Wildland Fires Within the U.S.

E.F. Clarification of and Changes to the Required Content of Progress Reports 

F.G. Changes to Reasonably Attributable Visibility Impairment Provisions 

G.H. Consistency Revisions Related to Permitting of New and Modified Major Sources 

H.I. Changes to FLM Consultation Requirements 

I.J. Extension of Next Regional Haze SIP Deadline from 2018 to 2021 

J.K. Changes to Scheduling of Regional Haze Progress Reports 

K.L. Changes to the Requirement that Regional Haze Progress Reports be SIP 

Revisions 

L.M. Changes to Requirements Related to the Grand Canyon Visibility Transport 

Commission 

V. Environmental Justice Considerations 

VI. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: 

Improving Regulation and Regulatory Review 

B. Paperwork Reduction Act (PRA) 

C. Regulatory Flexibility Act (RFA) 

D. Unfunded Mandates Reform Act (UMRA) 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045: Protection of Children from Environmental Health and Safety 

Risks 

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect 

Energy Supply, Distribution or Use 

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations 

VII. Statutory Authority 

II. What action is the EPA proposing to take? 

The EPA is proposing changes to the requirements that states (and, if applicable, tribes) 

would have to meet as they implement programs for the protection of visibility in mandatory 
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Class I areas.2 This proposal would support continued environmental progress by clarifying 

certain or revising existing regulatory provisions and removing older rule provisions that have 

been superseded by subsequent developments. The EPA is proposing to clarify the relationship 

between long-term strategies and reasonable progress goals in state plans and the long-term 

strategy obligation of all states. The EPA is also proposing to revise the way in which some days 

during each year are to be selected for purposes of tracking progress towards natural visibility 

conditions in order to focus attention on days when anthropogenic emissions impair visibility; 

revise aspects of the requirements for the content of progress reports; update, simplify and 

extend to all states the provisions for reasonably attributable visibility impairment and revoke 

existing FIPs that require the EPA to assess and address any existing reasonably attributable 

visibility impairment situations in some states; and add a requirement for states to consult with 

FLMs earlier in the development of state plans. Other changes address administrative aspects of 

the program in order to reduce unnecessary burden. Specifically, the EPA proposes to make a 

one-time adjustment to the due date for the next SIPs (from 2018 to 2021, which would help 

states to coordinate regional haze planning with that for other programs such as the Clean Power 

Plan), to revise the due dates for progress reports and to remove the requirement for progress 

 

2

 Areas designated as mandatory Class I 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. 42 U.S.C. 7472(a). In accordance with section 169A of 

the CAA, the EPA, in consultation with the Department of Interior, promulgated a list of 156 

areas where visibility is identified as an important value. 44 FR 69122 (November 30, 1979). 

The extent of a mandatory Class I area includes subsequent changes in boundaries, such as park 

expansions. 42 U.S.C. 7472(a). Although states and tribes may designate as Class I additional 

areas that they consider to have visibility as an important value, the requirements of the visibility 

program set forth in section 169A of the CAA apply only to “mandatory Class I Federal areas.” 

Each mandatory Class I federal area is the responsibility of a “Federal Land Manager.” 42 

U.S.C. 7602(i). When we use the term “Class I area” in this action, we mean any one of the 156 

“mandatory Class I Federal areas” where visibility has been identified as an important value. 
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reports to be SIP revisions. All of these changes would apply to periodic comprehensive state 

implementation plans developed for the second and subsequent implementation periods and for 

progress reports submitted subsequent to those plans. We do not intend the proposed changes to 

affect the development of state plans for the first implementation period or the first progress 

reports due under the existing Regional Haze Rule. 

The EPA is proposing these changes for several reasons, as described more fully in the 

descriptions of each change detailed later in this proposed action. The proposed clarifications 

regarding the relationship between reasonable progress goals, long-term strategies and the longterm strategy obligation of all states reflect long-standing EPA interpretation of the Regional 

Haze Rule and are intended to ensure consistent (and appropriate) understanding of these 

requirements as states prepare their plans for the second implementation period. Changes to FLM 

consultation requirements would help ensure that the expertise and perspective of these officials 

are brought into the state plan development process earlier, so that they contribute meaningfully 

during the state’s technical analysis and deliberations. The proposals related to how days are 

selected for visibility progress tracking would provide the public and state officials more 

meaningful information on how existing and potential new emission reduction measures are 

contributing or could contribute to reasonable progress in reducing man-made visibility 

impairment, by greatly reducing the trend-distorting effect of wildfires and natural dust storms. 

Collectively, these changes would serve to strengthen the regional haze program based upon 

lessons learned during the decade and a half since the program’s inception. 

With regard to the proposed extension of the current deadline of July 31, 2018, to July 

31, 2021, for states’ comprehensive SIP revisions for the second implementation period, the EPA 

believes this one-time change would benefit states by allowing them to obtain and take into 
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account information on the effects of a number of other regulatory programs that will be 

affecting sources over the next several years. The change would also allow states to develop SIP 

revisions for the second implementation period that are more integrated with state planning for 

these other programs, an advantage that was widely confirmed in discussions with states and that 

is anticipated to result in greater environmental progress than if planning for these multiple 

programs were not as well integrated. The end date for the second implementation period 

remains 2028, meaning state plans will still focus on emission reduction measures designed to 

achieve reasonable progress by 2028,3 as required by the current rule. Note that oOther than the 

proposed one-time change to the next due date for periodic comprehensive SIP revisions (i.e., for 

those currently due in 2018), no change is being proposed for due dates for future periodic 

comprehensive SIP revisions. 

 The proposed changes related to progress reports are intended to make the timing of 

progress reports more useful as mid-course reviews, to clarify the required content of progress 

reports for aspects on which there has been some ambiguity, and to allow states to conserve their 

administrative resources and make progress reports more timely by removing the requirement 

that they be submitted as formal SIP revisions. We are proposing to retain a requirement that 

states consult with FLMs on their progress reports, and that states offer the public an opportunity 

to comment on progress reports before they are finalized, which are two of the steps that apply 

now to progress reports that are SIP revisions and which will help ensure ongoing accountability 

for progress reports. 

 

3

 When considering the “time necessary for compliance,” see 42 USC 7491(g)(1), a state should 

account for this factor by setting an appropriate compliance schedule. The EPA expects that any 

control measure included in a SIP submitted by the proposed July 31, 2021, submission deadline 

will be feasible to implement by 2028. 
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Finally, the current provisions related to reasonably attributable visibility impairment 

require a recurring process of assessment and planning by the states. Experience since the current 

provisions were promulgated suggests that situations involving reasonably attributable visibility 

impairment occur infrequently and therefore that an “as needed” approach for initiating a state 

planning obligation would be more efficient in the use of resources. The EPA is proposing to 

replace the recurring process of assessment of reasonably attributable visibility impairment with 

an as- needed approach, and given our increased understanding of the interstate nature of 

visibility impairment, to expand the applicability for reasonably attributable visibility 

impairment from only states with Class I areas to all states. The proposed change to an asneeded approach only applies to reasonably attributable visibility impairment; periodic planning 

for purposes of regional haze will continue. This would improve visibility protection, if a 

situation exists or arises in which a source in a state without any Class I area causes reasonably 

attributable visibility impairment at a Class I area in another state. 

 The EPA also intends to also provide states with updated guidance on the development of 

regional haze SIPs, in consultation with the states and FLMs, separately from this rulemaking. 

The guidance will assist states as they refocus on reasonable progress analyses for the next 

regional haze implementation period ending in 2028. We expect to invite public comment on a 

draft of this new guidance, and we expect to receive and be able to consider those comments 

before we finalize the Regional Haze Rule revisions.

III. What is the background for the EPA’s proposed action? 

A. Reasonably Attributable Visibility Impairment 

In section 169A of the 1977 Amendments to the CAA, Congress created a program for 

protecting visibility in the nation’s national parks, wilderness areas, national forests and other 
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Class I areas due to their “great scenic importance.”4 This section of 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.” 

In 1980, the EPA promulgated regulations to address visibility impairment in Class I 

areas, including but not limited to impairment that is “reasonably attributable” to a single source 

or small group of sources, i.e., “reasonably attributable visibility impairment.” 45 FR 80084 

(December 2, 1980). These regulations, codified at 40 CFR 51.300 through 51.307, represented 

the first phase in addressing visibility impairment from existing sources. They also addressed 

potential visibility and other air quality-related impacts from new and modified major sources 

already subject to permitting requirements for purposes of protection of the National Ambient 

Air Quality Standards (NAAQS) and preventing significant deterioration of air quality. The EPA 

explicitly deferred action on regional haze (visibility-impairing pollution that is caused by the 

emission of air pollutants from numerous sources located over a wide geographic area) until 

some future date when improvement in monitoring techniques provideds more data on sourcespecific levels of visibility impairment, regional scale models becaome refined, and our scientific 

knowledge about the relationships between emitted air pollutants and visibility impairment 

improveds. 

It is important to note that not all states were subject to the 1980 reasonably attributable 

visibility impairment requirements. Under the 1980 rules, the 35 states and one territory (Virgin 

Islands) containing Class I areas were required to submit SIPs addressing reasonably attributable 

 

4

 H.R. Rep. No. 294, 95th Cong. 1st Sess. at 205 (1977). 
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visibility impairment. The 1980 rules required states to (1) develop, adopt, implement and 

evaluate long-term strategies for making reasonable progress toward remedying existing and 

preventing future impairment in the mandatory Class I areas through their SIP revisions; (2) 

adopt certain measures to assess potential visibility impacts due to new or modified major 

stationary sources, including measures to notify FLMs of proposed new source permit 

applications, and to consider visibility analyses conducted by FLMs in their new source 

permitting decisions; (3) conduct visibility monitoring in mandatory Class I areas, and (4) revise 

their SIPs at 3-year intervals to assure reasonable progress toward the national visibility goal. In 

addition, the 1980 regulations provided that an FLM may certify to a state at any time that 

visibility impairment at a Class I area is reasonably attributable to a single source or small group 

of sources. Following such a certification by an FLM, a state is required to address the 

requirements for best available retrofit technology (BART) for BART-eligible sources 

considered to be contributing to reasonably attributable visibility impairment. Also, the 

appropriate control of any source certified by an FLM, whether BART-eligible or not, would 

logically be specifically addressed in the long-term strategy for making reasonable progress 

toward the national goal of natural visibility conditions. as required by existing See existing 

§51.302(c)(2)(i). 

In practice, the 1980 rules resulted in few SIPs being submitted by states and approved by 

the EPA, requiring the EPA to develop and apply FIPs to those states that failed to submit an 

approvable reasonably attributable visibility impairment SIP. 52 FR 45132 (November 24, 

1987). Most of these FIPs contain planning requirements only, i.e., most of the FIPs merely 

commit the EPA to assessing on a 3-year cycle whether reasonably attributable visibility 
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impairment is occurring and to adopting an appropriate strategy of required emission controls if 

it is. 

We are proposing extensive changes to the existing provisions regarding reasonably 

attributable visibility impairment to improve coordination with the regional haze program 

requirements and enhance the potential for environmental protection, as described in the 

“Proposed Rule Changes” section of this document (section IV.G). 

B. Regional Haze 

Regional haze is visibility impairment that is produced by a multitude of sources and 

activities that are located across a broad geographic area and emit PM10, PM2.5 (e.g., sulfates, 

nitrates, organic carbon, elemental carbon and soil dust) and their precursors (e.g., SO2, NOx 

and, in some cases, ammonia and volatile organic compounds). Fine particle precursors react in 

the atmosphere to form PM2.5, which impairs visibility by scattering and absorbing light. This 

light scattering reduces the clarity, color and visible distance that one can see. Particulate matter

can also cause serious health effects in humans (including premature death, heart attacks, 

irregular heartbeat, aggravated asthma, decreased lung function and increased respiratory 

symptoms) and contribute to environmental effects such as acid deposition and eutrophication. 

Data from the existing visibility monitoring network, the “Interagency Monitoring of 

Protected Visual Environments” (IMPROVE) monitoring network, show that at the time the 

Regional Haze Rule was finalized in 1999, visibility impairment caused by air pollution occurred 
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virtually all the time at most national park and wilderness areas. The average visual range5 in 

many Class I areas in the western U.S. was 62–93 miles, but in some Class I areas, these visual 

ranges may have been impacted by natural wildfire and dust episodes in addition to 

anthropogenic impacts. In most of the eastern Class I areas of the U.S., the average visual range 

was less than 19 miles. 64 FR 35715 (July 1, 1999).

Based on visibility data through 2014, considerable visibility improvements (4 to 7 

deciviews)6 have been made in eastern Class I areas on the 20 percent haziest days. Some 

western Class I areas have also experienced visibility improvements on the 20 percent haziest 

days (1 to 4 deciviews). However, in some areas, such as Sawtooth Wilderness area in Idaho, 

improvements from reduced emissions from man-made sources have been overwhelmed by 

uncontrollable impacts from fire wildfire and/or dust events. There are also some western areas 

where visibility has changed only by a slight amount. 

1. Requirements of the 1990 CAA Amendments and the EPA’s Regional Haze Rule 

Congress added section 169B to the CAA in 1990 to address regional haze issues. 

Among other things, this section included provisions for the EPA to conduct visibility research 

on regional regulatory tools with the National Park Service and other federal agencies, and to 

provide periodic reports to Congress on visibility improvements due to implementation of other 

 

5

 Visual range is the greatest distance, in kilometers or miles, at which a dark object can be 

discerned against the sky by a typical observer. Visual range is inversely proportional to light 

extinction (bext) by particles and gases and is calculated as: Visual Range = 3.91/bext (Bennett, 

M.G., The physical conditions controlling visibility through the atmosphere; Quarterly Journal of 

the Royal Meteorological Society, 1930, 56, 1-29). Light extinction has units of inverse distance 

(i.e., Mm-1 or inverse Megameters [mega = 106]). 

6

 The deciview haze index (discussed in more detail in Section III.B.3) is logarithmically related 

to light extinction and is used by the regional haze program because it describes uniform 

differences in visibility across a range of visibility conditions.
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air pollution protection programs. Section 169B also generally allowed the Administrator to 

establish visibility transport commissions and specifically required the Administrator to establish 

a commission for the Grand Canyon area. The EPA promulgated a rule to address regional haze 

in 1999. 64 FR 35714 (July 1, 1999). The 1999 Regional Haze Rule established a more 

comprehensive visibility protection program for Class I areas. The requirements for regional 

haze are found at 40 CFR 51.308 and 51.309. 

The requirement to submit a regional haze SIP applies to all 50 states, the District of 

Columbia and the Virgin Islands.7 Congress subsequently amended the deadlines for regional 

haze SIPs, and the EPA adopted regulations requiring states to submit the first implementation 

plans addressing regional haze visibility impairment no later than December 17, 2007. 70 FR 

39104. These initial SIPs were to address emissions from certain large stationary sources and 

other requirements, which we discuss in greater detail later. Few states submitted a regional haze 

SIP by the December 17, 2007, deadline, and on January 15, 2009, the EPA found that 37 states, 

the District of Columbia and the Virgin Islands had failed to submit SIPs addressing the regional 

haze requirements. 74 FR 2392. Because of these findings,These findings triggered a CAA 

section 110(c)(1) requirement fors the EPA to promulgate a FIPs within 2 years unless the a state 

submitteds a SIP and the agency EPA approveds it that SIP within the 2-year period. CAA 

 

7

 This requirement does not apply to other U.S. territories because they do not have mandatory 

Class I Federal areas, and they are too distant from any such areas to affect them.
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section 110(c). Most states eventually submitted SIPs, The EPA has fulfilled most, but not all, of 

these FIP obligations.8. 

Further, 40 CFR 51.308(f) currently requires states to submit periodic comprehensive 

revisions of implementation plans (referred to in this document as periodic comprehensive SIP 

revisions) addressing regional haze visibility impairment by no later than July 31, 2018, and 

every 10 years thereafter. These periodic comprehensive SIP revisions must address a number of 

elements, including current visibility conditions and actual progress made toward natural 

conditions during the previous implementation period;, a reassessment of the effectiveness of the 

long-term strategy for in the achieving the ement of reasonable progress goals over the prior 

implementation period;, and affirmation of or revision to the reasonable progress goals. Further 

information on these periodic comprehensive SIP revisions can be found in section III.B.3 of this 

document. In addition, 40 CFR 51.308(g) requires each state to submit progress reports, in the 

form of SIP revisions, every 5 years counting from the submission of the initial SIP due on 

December 17, 2007after the date of the state’s initial SIP submission. These progress reports are 

required to evaluate the progress made towards the reasonable progress goals for mandatory 

Class I areas located within the state, as well as those mandatory Class I areas located outside the 

state that may be affected by emissions from within the state. Further information on these 

progress reports can be found in section III.B.4 of this document. 

 

8 All states and territories, with the exception of HawaiiI, MontanaT, and the Virgin Islands,I 

submitted initial regional haze SIPs. Most states now have an approved SIP or FIP in place. 

[NOTE TO OMB: This footnote will be expanded to describe the up-to-date status of SIPs and 

FIPs at time of rule proposal publication, reflecting ongoing litigation that may affect SIP/FIP 

status at that time. The states that do not yet have a complete and approved SIP or complete FIP 

in place include AL, AR, LA, MT, ND, MS, MT, PA and TX. In addition, pending litigation 

might result in remands of portions of SIP actions and/or FIPs in other states including AZ and 

WY. ]
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The 1999 Regional Haze Rule sought to improve efficiency and transparency by 

requiring states to coordinate their planning under the 1980 reasonably attributable visibility 

impairment provisions with their planning under the provisions added by the 1999 Regional 

Haze Rule. The states were directed to submit reasonably attributable visibility impairment SIPs 

every 10 years rather than the previously required every 3 years, and to do so as part of the newly 

required regional haze SIPs. Many, but not all, states submitted initial regional haze SIPs that 

committed to this coordinated planning process. Coordination of reasonably attributable 

visibility impairment and regional haze planning is described in more detail later. 

2. Roles of Agencies in Addressing Regional Haze 

Successful implementation of the regional haze program requires long-term regional 

coordination among states, tribal governments and various federal agencies. As noted earlier, 

pollution affecting the air quality in Class I areas can be transported over long distances, even 

hundreds of miles. Therefore, to effectively address the problem of visibility impairment in Class 

I areas, states need to develop strategies in coordination with one another, taking into account the 

effect of emissions from one jurisdiction on the air quality in another. 

Because the pollutants that lead to regional haze can originate from sources located 

across broad geographic areas, and because these sources may be numerous and emit amounts of 

pollutants that, even though small, contribute to the collective whole, the EPA has encouraged 

the states across the U.S. to address visibility impairment from a regional perspective. Five 

regional planning organizations (RPOs) were formed after the promulgation of the Regional 

Haze Rule in 1999 to address regional haze and related issues. The RPOs first evaluated 

technical information to better understand how their states and tribes impact Class I areas across 
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the country, and then supported the development (by states) of regional strategies to reduce 

emissions of pollutants that lead to regional haze.

3. Requirements for the Regional Haze SIPs 

The following is a summary of the requirements for the periodic comprehensive SIP 

revisions under the 1999 Regional Haze Rule. See 40 CFR 51.308 and 51.309 for further detail 

regarding the requirements of the rule. 

The Regional Haze Rule required the implementation plans due in 2007, which 

covereding what we refer to as the first implementation period, were required to give specific 

attention to certain stationary sources that were in existence on August 7, 1977, but were not in 

operation before August 7, 1962, by requiring these sources, where appropriate, to install BART 

controls for the purpose of eliminating or reducing visibility impairment. The following 

paragraphs describe the one-time BART requirement and the specific regional haze SIP 

requirements that continue to apply for the second and subsequent implementation periods.

BART Requirement. Section 169A of the CAA directs states to evaluate the use of retrofit 

controls at certain larger, often uncontrolled, older stationary sources in order to address 

visibility impacts from these sources. Specifically, section 169A(b)(2)(A) of the CAA requires 

states to revise their SIPs to include such measures as may be necessary to make reasonable 

progress towards the natural visibility goal, including a requirement that certain categories of 

existing major stationary sources9

 procure, install, and operate BART as determined by the state. 

Under the Regional Haze Rule, the EPA directed states are directed to conduct BART 

 

9

 The set of “major stationary sources” potentially subject-to-BART is listed in CAA section 

169A(g)(7). 
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determinations for such any “BART-eligible” sources10” sources that may be anticipated to cause 

or contribute to any visibility impairment in a Class I area. The EPA published the Guidelines for 

BART Determinations Under the Regional Haze Rule at appendix Y to 40 CFR part 51 

(hereinafter referred to as the “BART Guidelines”) to assist states in determining which of their 

sources should be subject to the BART requirements and in determining appropriate emission 

limits for each applicable source. 70 FR 39104 (July 6, 2005). The Regional Haze Rule also 

provides an alternative to requiring source-specific BART controls; under EPA’s regulations, 

gives states have the flexibility to adopt an emissions trading program or other alternative 

program in lieu of source-specific BART as long as the alternative provides greater reasonable 

progress towards improving visibility than BART and meets certain other requirements set out in 

40 CFR 51.308(e)(2). 

States undertook the BART determination process during the first regional haze 

implementation period; thus the details of the process for establishing BART emission 

limitations are not material to the changes proposed in this document. Although the BART 

process is not repeated in subsequent implementation periodsThe BART requirement was a onetime requirement, but BART-eligible sources may need to be re-assessed for more additional 

controls in later future implementation periods as part of the requirement to provide for 

reasonable progress as described laterunder the CAA’s reasonable progress provisions. 

Specifically, we anticipate that BART-eligible sources that installed minor controls (or no 

controls at all) will need to be reassessed. States should treat BART-eligible sources the same as 

 

10 BART-eligible sources are those sources that have the potential to emit 250 tons or more of a 

visibility-impairing air pollutant, were not in operation prior to August 7, 1962, but were in 

existence on August 7, 1977, and whose operations fall within one or more of 26 specifically 

listed source categories. 40 CFR 51.301. 
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other reasonable progress sources going forward. Consequently, Wwe are not proposing any 

changes to the BART provisions in this rulemaking.

Visibility Metric. The Regional Haze Rule established a standard, conventional approach 

to quantifying visibility conditions and tracking how it they is changingchanges over time. The 

Regional Haze Rule established the 24-hour deciview haze index as the principal metric or unit 

for expressing visibility on for any particular day. See 70 FR 39104, 39118. The deciview haze 

index is calculated from light extinction values, and this index expresses uniform changes in the 

degree of haze in terms of common increments across the entire range of visibility conditions, 

from pristine to extremely hazy conditions. Visibility expressed in deciviews is 

determinedDeciview values are calculated by using air quality measurements to estimate light 

extinction, most recently using the revised IMPROVE algorithm, and then transforming the 

value of light extinction using a logarithmic function.11 The deciview is a more useful measure 

for comparing days and tracking progress in improving visibility than light extinction itself 

because each deciview change is an equal incremental change in visibility typically perceived by 

a human observer. Most people can detect a change in visibility at of one deciview. The 

preamble to the 1999 Regional Haze Rule provides additional details about the deciview haze 

index. We are proposing minor editorial changes to definitions related to the deciview index in 

order for there to be ensure more consistent terminology across sections of the Regional Haze 

Rule. 

 

11 Pitchford, M.; Malm, W.; Schichtel, B.; Kumar, N.; Lowenthal, D.; Hand, J. Revised 

algorithm for estimating light extinction from IMPROVE particle speciation data; J. Air & Waste 

Manage. Assoc. 2007, 57, 1326-1336; doi: 3155/1047-3289.57.11.1326. 
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Baseline, Current and Natural Conditions and Tracking Changes in Visibility. To track 

changes in visibility over time at each of the 156 Class I areas covered by the visibility program 

(40 CFR 81.401–437), and as part of the process for determining reasonable progress as 

described later, states must calculate the degree of existing visibility impairment conditions at 

each Class I area for a 5-year period just preceding each periodic comprehensive SIP revision.

12

 

and, under the current version of the Regional Haze Rule, periodically review progress in 

reducing impairment every 5 years. To do this, the Regional Haze Rule requires states to 

determine the average visibility conditionsdegree of impairment (in deciviews) for the average of 

the 20 percent least impaired days and the 20 percent most impaired visibility days over a 

specified timethe 5-year period at each of their Class I areas. 

States must also develop an estimate of natural visibility conditions for the purpose of 

estimating progress toward the national goal of preventing future and remedying existing 

visibility impairment from manmade air pollution. Natural visibility is determined by estimating 

the natural concentrations of pollutants that cause visibility impairment and then calculating total 

light extinction based on those estimates. The EPA has provided guidance to states regarding 

how to calculate baseline, natural and current visibility conditions at each Class I area.

13 After 

the EPA issued this guidance, a number of interested parties developed an alternative set 

 

12 Under the current version of the Regional Haze Rule, states must also periodically review 

progress in reducing impairment every 5 years.

13 Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule, 

September 2003, EPA–454/B–03–005, available at 

http://www3.epa.gov/ttn/caaa/t1/memoranda/rh_envcurhr_gd.pdf; and Guidance for Tracking 

Progress Under the Regional Haze Rule, September 2003, EPA–454/B–03–004, available at 

http://www3.epa.gov/ttn/oarpg/t1/memoranda/rh_tpurhr_gd.pdf. 
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estimates of natural conditions using a more refined approach (known as “NC-II”), which were 

used by most states in their first regional haze SIPs with EPA approval.14

 Baseline visibility conditions represent reflect the degree of visibility impairment for the 

20 percent least impaired days and 20 percent most impaired days for each calendar year from 

2000 to 2004. Using monitoring data for 2000 through 2004, states are required to calculate the 

average degree of visibility impairment for each Class I area, based on the average of annual 

values over the 5-year period. The comparison of initial baseline visibility conditions to natural 

visibility conditions indicates the amount of improvement that would be necessary to attain 

natural visibility. Over time, the comparison of current conditions15 to the baseline conditions 

will indicate the amount of progress that has been made. 

The rule text adopted in 1999 defined “visibility impairment” as a humanly perceptible 

change (i.e., difference) in visibility from that which would have existed under natural 

conditions. The rule text directed the tracking of visibility impairment on the 20 percent “most 

impaired days” and 20 percent “least impaired days” in order to determine progress towards 

natural visibility conditions. Section 51.308(d)(2)(i-iv). In light of the 1999 rule’s definition of 

 

14 Regional Haze Rule Natural Level Estimates Using the Revised IMPROVE Aerosol 

Reconstructed Light Extinction Algorithm, available at 

http://vista.cira.colostate.edu/improve/Publications/GrayLit/032_NaturalCondIIpaper/Copeland

_etal_NaturalConditionsII_Description.pdf; Revised IMPROVE Algorithm for Estimating Light 

Extinction from Particle Speciation Data, available at 

http://vista.cira.colostate.edu/improve/Publications/GrayLit/019_RevisedIMPROVEeq/RevisedI

MPROVEAlgorithm3.doc; and Regional Haze Data Analysis Workshop, June 8, 2005, Denver, 

CO, agenda and documents available at 

http://www.wrapair.org/forums/aamrf/meetings/050608den/index.html. 

15 Given the required timing of the first regional haze SIPs that were due by December 17, 2007, 

“baseline visibility conditions” were also the “current” visibility conditions. For future SIPs, 

“current conditions” will be updated to the 5-year period just preceding the SIP revision. 
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“impairment,” the term “impaired” in the phrases “most impaired days” and “least impaired 

days” could be taken to connote anthropogenic impairment. However, the preamble to the 1999 

final rule stated that the least and most impaired days were to be selected as the monitored days 

with the lowest and highest actual deciview levels, respectively. In 2003, the EPA issued 

guidance describing in detail the steps necessary for selecting and calculating light extinction on 

the “worst” and “best” visibility days, and this guidance also indicated that the monitored days 

with the lowest and highest actual deciview levels were to be selected as the least and most 

impaired days.16 This approach has worked well in many Class I areas but has not in other areas. 

Specifically, the “worst” visibility days in some Class I areas can be impacted by natural 

emissions (e.g., wildland wildfires and dust storms). These natural contributions to haze vary in 

magnitude and timing. Anticipating this variability, in the 1999 Regional Haze Rule the EPA had 

decided to use 5-year averages of visibility data to minimize the impacts of the interannual 

variability in natural events. However, as the IMPROVE monitoring network has collected more 

years of data, it has become obvious that in many Class I areas 5-year averages are not sufficient 

for minimizing these impacts. As a result, visibility improvements resulting from decreases in 

anthropogenic emissions can be hidden in this uncontrollable natural variability. In addition, 

because of the logarithmic deciview scale, changes in PM concentrations and light extinction due 

to reductions in anthropogenic emissions have little effect on the deciview value on days with 

high PM concentrations and light extinction due to natural sources. The use of the days with the 

highest deciview index values, without consideration of the source of the visibility impacts, thus 

has created difficulties when attempting to track visibility improvements resulting from controls 

 

16 Guidance for Tracking Progress Under the Regional Haze Rule, September 2003, 

http://www3.epa.gov/ttnamti1/files/ambient/visible/tracking.pdf.
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on anthropogenic sources. States have identified this difficulty and asked that the EPA explore 

options for focusing the visibility tracking metric on controllable anthropogenic emissions. To 

help states minimize the impacts of uncontrollable emissions on visibility tracking, the EPA is 

proposing to more explicitly (and consistently) address this issue for future implementation 

periods in the “Proposed Rule Changes” section of this document (sections IV.C. and IV.D). 

Reasonable Progress Goals and Long-Term Strategy. To ensure continuing progress 

towards achieving the natural visibility goal, each SIP in the series of periodic comprehensive 

regional haze SIPs must establish two distinct reasonable progress goals (one for the most 

impaired and one for the least impaired days) for every Class I area for the following 

implementation period. See 40 CFR 51.308(d) and (f). The Regional Haze Rule does not 

mandate specific milestones or rates of progress, but instead calls for states to establish goals that

provide for “reasonable progress” toward achieving natural visibility conditions. In setting 

reasonable progress goals, states must provide for an improvement in visibility for the most 

impaired days over the period of the SIP, and ensure no degradation in visibility for the least 

impaired days over the same period. Id. Consistent with the requirement in section 169A(b) of 

the CAA that states include in their regional haze SIPs a 10- to 15-year strategy for making 

reasonable progress, §51.308(d)(3) of the Regional Haze Rule requires that states include their 

long-term strategy in their regional haze SIPs. The reasonable progress goals themselves, 

however, are not enforceable. 64 FR 35754. 

In establishing reasonable progress goals, states are required to consider the following 

factors set out in the definition of “reasonable progress” in section 169A of the CAA and 

incorporated into the Regional Haze Rule at 40 CFR 51.308(d)(1)(i)(A): (1) the costs of 

compliance; (2) the time necessary for compliance; (3) the energy and non-air quality 
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environmental impacts of compliance; and (4) the remaining useful life of any potentially 

affected sources. States must demonstrate in their SIPs how these factors have been considered 

when selecting the reasonable progress goals for the least impaired and most impaired days for 

each applicable Class I area. It is important to understand that a state’s long-term strategy is 

inextricably linked to the reasonable progress goals because the long-term strategy “must include 

enforceable emission limitations, compliance schedules, and other measures as necessary to 

achieve the reasonable progress goals established by states having mandatory Class I Federal 

areas.” 40 CFR 51.308(d)(3). As intended by the EPA and as understood by all states in the first 

implementation period, the four reasonable progress factors are considered by a state in setting 

the reasonable progress goal by virtue of the state having first considered them, and certain other 

factors listed in §51.308(d)(3) of the Regional Haze Rule, when deciding what controls are to be 

included in the long-term strategy. Then, the numerical levels of the reasonable progress goals 

are the predicted visibility outcome of implementing the long-term strategy in addition to 

ongoing pollution control programs stemming from other CAA requirements. To ensure 

consistent understanding about the relationship between reasonable progress goals and the longterm strategy, we are proposing rule text changes to clarify this relationship in the “Proposed 

Rule Changes” section of this document (section IV.A). The proposed rule text is consistent with 

our long-held interpretation of the existing rule text as stated earlier.17

In deciding on the long-term strategy and in setting the reasonable progress goals, states 

must also consider the rate of progress for the most impaired days that would be needed to reach 

 

17 The EPA’s interpretation of the proper relationship between a state’s reasonable progress goals 

and its long-term strategy is explained in detail in our proposed action on SIPs from Texas and 

Oklahoma. See section IV.C at 79 FR 74828. This interpretation was reaffirmed in our final 

action on these SIPs. See section II.CB of 81 FR 296 (January 5, 2016). 
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natural visibility conditions by 2064 [referred to as the “uniform rate of progress” (URP)] and 

the emission reduction measures that would be needed to achieve that rate of progress over the 

approximately 10-year period of the SIP. Uniform progress towards achievement of natural 

conditions by the year 2064 represents a rate of progress that states are to use for analytical 

comparison to the amount of progress they expect to achieve on average. The CAA has the goal 

of reaching natural conditions,18 but does not have any date for achievement of that goal, 

requiring only that plans demonstrate reasonable progress towards it. The Regional Haze Rule 

reiterates the CAA goal, and provides for the use of an analytical framework that compares the 

rate of progress that will be achieved by a SIP (as represented by the reasonable progress goals 

for the end of the implementation period) to the rate of progress that if continued would result in 

natural conditions in 2064 (i.e., the URP). When a SIP contains a reasonable progress goal for 

the most impaired days that reflects progress that is equal to the URP, the reasonable progress 

goal is said to be “on the URP line” or “on the glidepath.” If a state’s reasonable progress goal 

for the most impaired days is not on the glidepath, §51.308(d)(1)(ii) requires the state to 

demonstrate that it would not be reasonable to adopt a reasonable progress goal (and by 

implication a long-term strategy) that would be on the glidepath. The Regional Haze Rule does 

not establish an enforceable requirement that natural conditions be reached in 2064. The EPA 

has approved a number of SIPs for the first implementation period that have projected that 

 

18 The text of the Regional Haze Rule states the goal of achieving “natural visibility conditions.” 

While section 169A(a)(1) of the CAA calls for “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,” litigation over the Regional Haze Rule has indicated the 

visibility goals stated in the CAA means achievement of “natural visibility conditions.”
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continued progress at the rate expected to be achieved during that first period would not result in 

natural conditions until a date after 2064. 

In setting reasonable progress goals, each state with one or more Class I areas must also 

consult with potentially “contributing states,” i.e., other nearby states with emission sources that 

may be affecting visibility impairment in the state’s Class I areas. In such cases, the contributing 

state must demonstrate that it has included in its SIP all measures necessary to obtain its share of 

the emission reductions needed to meet the reasonable progress goals for the Class I area. 

Furthermore, section 169A(g)(1) of the CAA and §51.308(d)(1)(i)(A) of the Regional Haze Rule 

require that states determine “reasonable progress” by considering the four statutory factors. 

Also, §51.308(d)(3) requires each state to consider its own Class I areas (if it has any) and 

downwind Class I areas (which may be affected by emissions from the state) when it develops its 

long-term strategy. In determining whether a state’s long-term strategy and reasonable progress 

goals provide for reasonable progress toward natural visibility conditions, the EPA is required to 

evaluate the demonstrations developed by the state. 40 CFR 51.308(d)(1). To ensure consistent 

understanding about the long-term strategy obligations of all states, we are proposing rule text 

changes to clarify these obligations in the “Proposed Rule Changes” section of this document 

(section IV.B). The proposed rule text is consistent with our long-held interpretation of the 

existing rule text as stated earlier. 

In accordance with the Regional Haze Rule, states should consider all types of 

anthropogenic sources of visibility impairment in developing their long-term strategy, including 

major and minor stationary sources, mobile sources and area sources. At a minimum, states must 

describe how each of the following seven factors are taken into account in developing their longterm strategy: (1) Emission reductions due to ongoing air pollution control programs, including 
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measures to address reasonably attributable visibility impairment; (2) measures to mitigate the 

impacts of construction activities; (3) emissions limitations and schedules for compliance to 

achieve the reasonable progress goal; (4) source retirement and replacement schedules; (5) 

smoke management techniques for agricultural and forestry management purposes including 

plans as currently exist within the state for these purposes; (6) enforceability of emissions 

limitations and control measures; and (7) 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. 40 CFR 51.308(d)(3)(v). We are proposing to update the terminology in the fifth of 

these factors. We are not proposing any changes to the current requirements regarding these 

seventhe other six factors. 

As discussed earlier, the current version of the Regional Haze Rule requires control 

strategies to cover an initial implementation period extending to the year 2018, with a 

comprehensive reassessment and revision of those strategies, as appropriate, every 10 years 

thereafter. The reasonable progress goals are specific to the end date of a given implementation 

period. New reasonable progress goals for the end of the next period are established in the next 

periodic comprehensive SIP revision. We are proposing to extend, to July 31, 2021, the due date 

for the SIP revision that under the existing Regional Haze Rule is due July 31, 2018. This 

proposed change is discussed in the “Proposed Rule Changes” section of this document (section 

IV.J). 

 Coordinating Regional Haze and Reasonably Attributable Visibility Impairment. The 

1999 Regional Haze Rule fulfilled the EPA’s responsibility to put in place a national regulatory 

program that addresses both reasonably attributable and regional haze visibility impairment. As 

part of the Regional Haze Rule, the EPA revised 40 CFR 51.306(c) regarding reasonably 
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attributable visibility impairment assessment and planning to require that the reasonably 

attributable visibility impairment plan must continue to provide for a periodic review and SIP 

revision not less frequently than every 3 years until the date of submission of the state’s first plan

addressing regional haze visibility impairment, which was due December 17, 2007. On or before 

this date, the state must have revised its plan to provide for periodic review and revision of a 

coordinated long-term strategy for addressing reasonably attributable visibility impairment and 

regional haze, and the state must have submitted the first such coordinated long-term strategy 

with its first regional haze SIP. Under the current version of the regulations, future coordinated 

long-term strategies, and periodic progress reports evaluating progress towards reasonable 

progress goals, must be submitted consistent with the schedule for SIP submission and periodic 

progress reports set forth in 40 CFR 51.308(f) and 51.308(g), respectively. The periodic review 

of a state’s long-term strategy must report on both regional haze visibility impairment and 

reasonably attributable visibility impairment and must be submitted to the EPA in the form of a 

periodic comprehensive SIP revision. Under our proposed changes to the reasonably attributable 

visibility impairment provisions, described in detail in section IV.G, this coordinated approach to 

a state’s long-term strategies for regional haze and reasonably attributable visibility impairment 

would continue, but would apply only when the state is under an obligation to respond to a 

reasonably attributable visibility impairment certification. 

Monitoring Strategy and Other Implementation Plan Requirements. Section 51.308(d)(4) 

of the Regional Haze Rule includes the requirement for a monitoring strategy for measuring, 

characterizing and reporting of regional haze visibility impairment that is representative of all 

mandatory Class I areas within the state. The strategy must be coordinated with the monitoring 

strategy required in the current version of §51.305 for reasonably attributable visibility 
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impairment. Compliance with this requirement may be met through “participation” in the 

IMPROVE network.19 A state’s participation in the IMPROVE network includes state support 

for the use of CAA state and tribal assistance grants funds to partially support the operation of 

the IMPROVE network as well as its review and use of monitoring data from the network. The 

monitoring strategy was due with the first regional haze SIP, and under the current Regional 

Haze Rule it must be reviewed every 5 years as part of the progress reports. The monitoring 

strategy must also provide for additional monitoring sites if the IMPROVE network is not 

sufficient to determine whether reasonable progress goals will be met. To date, neither the EPA 

nor any state has concluded that the IMPROVE network is not sufficient in this way. The 

evolution of the IMPROVE network will be guided by a Steering Committee that has FLM, EPA 

and state participation, within the evolving context of available resources. It is the EPA’s 

objective that individual states will not be required to commit to providing monitoring sites 

beyond those planned to be operated by the IMPROVE program during the period covered by a 

SIP revision. The EPA also believes that if the IMPROVE program must discontinue a 

monitoring site, this would not be a basis for an approved regional haze SIP to be found 

inadequate, but rather the state, the federal agencies and the IMPROVE Steering Committee 

should work together to address the Regional Haze Rule requirements when the next SIP 

revision is developed. As described in section IV.F, we are proposing that progress reports from 

individual states no longer be required to review and modify as necessary the state’s monitoring 

strategy. We believe the IMPROVE Steering Committee structure, the requirement to review the 

 

19 While compliance with §51.308(d)(4) for regional haze may be met through participation in 

the IMPROVE network, additional analysis or techniques beyond participation in IMPROVE 

may be required for compliance with §51.305 for reasonably attributable visibility impairment. 
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monitoring strategy as part of the periodic comprehensive SIP revision, and the requirement for a 

state to consider any recommendations from the EPA or a FLM for additional monitoring for 

purposes of reasonably attributable visibility impairment will be sufficient to achieve the 

objective of the current progress report requirement to review the monitoring strategy. 

Consultation between States and FLMs. The existing Regional Haze Rule requires that 

states consult with FLMs before adopting and submitting their SIPs. 40 CFR 51.308(i). States 

must provide FLMs an opportunity for consultation, in person and at least 60 days prior to 

holding any public hearing on the SIP. This consultation must include the opportunity for the 

FLMs to discuss their assessment of impairment of visibility in any Class I area and to offer 

recommendations on the development of the reasonable progress goals and on the development 

and implementation of strategies to address visibility impairment. Further, a state must include in 

its SIP a description of how it addressed any comments provided by the FLMs. Finally, a SIP 

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, 

progress reports, and the implementation of other programs having the potential to contribute to 

impairment of visibility in Class I areas. We are proposing to require that states also consult with 

FLMs earlier in the development of their SIPs, as described in section IV.I. 

4. Requirements for the Regional Haze Progress Reports 

The current version of the Regional Haze Rule includes provisions for progress reports to 

be submitted at 5-year intervals, counting from the submission of the first required SIP revision 

by the particular state. The requirements for these reports are included for most states in 40 CFR 

51.308 (g) and (h). Three western states (New Mexico, Utah and Wyoming) exercised an option 

provided in the Regional Haze Rule to meet alternative requirements contained in 40 CFR 
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51.309 for their SIPs. For these three states, the requirements for the content of the 5-year 

progress reports are identical to those for the other states, but for these states the requirements for 

the reports are codified in 40 CFR 51.309(d)(10). This section specifies fixed due dates in 2013 

and 2018 for these progress reports. Regardless, the current Regional Haze Rule provides that 

these three states will revert to the progress report requirements in 40 CFR 51.308 after the 

report currently due in 2018. 

An explanation of the 5-year progress reports is provided in the preamble to the 1999 

Regional Haze Rule. 64 FR 35747 (July 1, 1999). This 5-year review is intended to provide an 

interim report on the implementation of, and, if necessary, mid-course corrections to, the 

regional haze SIP, which, as noted earlier, is prepared in 10-year increments. The progress report 

provides an opportunity for public input on the state’s (and the EPA’s) assessment of whether the 

approved regional haze SIP is being implemented appropriately and whether reasonable visibility 

progress is being achieved consistent with the projected visibility improvement in the SIP. 

Required elements of the progress report include: the status of implementation of all 

measures included in the regional haze SIP; a summary of the emissions reductions achieved 

throughout the state; an assessment of current visibility conditions and the change in visibility 

impairment over the past 5 years; an analysis tracking the change over the past 5 years in 

emissions of pollutants contributing to visibility impairment from all sources and activities 

within the state; an assessment of any significant changes in anthropogenic emissions within or 

outside the state that have occurred over the past 5 years that have limited or impeded progress in 

reducing pollutant emissions and improving visibility; an assessment of whether the current SIP 

elements and strategies are sufficient to enable the state (or other states with mandatory Class I 

areas affected by emissions from the state) to meet all established reasonable progress goals; a 
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review of the state's visibility monitoring strategy and any modifications to the strategy as 

necessary; and a determination of the adequacy of the existing SIP (including taking one of four 

possible actions).20 We are proposing a number of clarifications and changes to the requirements 

for the content of progress reports, as described in section IV.F. 

In accordance with 40 CFR 51.308(g) and 51.309(d)(10), progress reports must currently 

take the form of SIP revisions, so states must follow formal administrative procedures (including 

public review and opportunity for a public hearing) before formally submitting the 5-year 

progress report to the EPA. See 40 CFR 51.102, 40 CFR 51.103, and Appendix V to Part 51 – 

Criteria for Determining the Completeness of Plan Submissions. We are proposing to remove the 

requirement that progress reports be submitted as SIP revisions, as described in section IV.L. 

In addition, as with SIPs, states are required to provide FLMs with an opportunity for inperson consultation at least 60 days prior to any public hearing on an implementation plan or 

plan revision, which must include an opportunity for FLMs to discuss their assessment of 

impairment of visibility in any mandatory Class I area, and discuss their recommendations on the 

development of reasonable progress goals and the development of implementation strategies to 

address visibility impairment. See 40 CFR 51.308(i)(2) and (3). Procedures must also be 

provided for continuing consultation between the state and FLM regarding development and 

review of progress reports. See 40 CFR 51.308(i)(4). We are proposing to preserve the existing 

requirement for consultation with FLMs on progress reports. 

 

20 40 CFR 51.308(g). See also General Principles for the 5-Year Regional Haze Progress Reports 

for the Initial Regional Haze State Implementation Plans (Intended to Assist States and EPA 

Regional Offices in Development and Review of the Progress Reports), April 2013, EPA–

454/B–03–005, available at http://www.4cleanair.org/Documents/haze_5year_4-10-13.pdf, 

(hereinafter referred to as “our 2013 Progress Report Guidance”). 
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The first progress reports are currently due 5 years from the initial SIP submittal (with the 

next progress reports for New Mexico, Utah, and Wyoming due in 2018). Most of these 

deadlines have already passed although some are due in 2016 and in 2017. We are proposing a 

set of common due dates for future progress reports from all states, as described in section IV.K. 

5. Tribes and Regional Haze 

Tribes have a distinct interest in regional haze due to the effects of visibility impairment 

on tribal lands as well as on other lands of high value to tribal members, such as landmarks 

considered sacred. Tribes, therefore, have a strong interest in emission control measures that 

states and the EPA incorporate into SIPs and FIPs with regard to regional haze, and also have an 

interest in the state response to any reasonably attributable visibility impairment certification 

made by an FLM. 

The EPA takes seriously our Federal Indian trust responsibility and the government-togovernment relationship with tribes.21 The agency has a tribal consultation policy that covers any 

plan that the EPA would promulgate that may affect tribal interests. This consultation policy 

applies to situations where a potentially affected source is located on tribal land, as well as 

situations where a SIP or FIP concerns a source that is located on state land and may affect tribal 

land or other lands that involve tribal interests. In addition, the EPA has and will continue to 

consider any tribal comments on any proposed action on a SIP or FIP. 

 

21 Like the EPA, the Department of the Interior and the U.S. Forest Service in the U.S. 

Department of Agriculture have strong tribal consultation policies. See: 

http://www.epa.gov/tribal/consultation/index.htm; 

http://www.fs.fed.us/spf/tribalrelations/authorities.shtml, and 

https://www.doi.gov/tribes/Tribal-Consultation-Policy. 
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In the first implementation period for regional haze SIPs, the partnerships within the 

RPOs included strong relationships between the states and the tribes, and the EPA encourages 

states to continue to invest in those relationships (including consulting with tribes), particularly 

with respect to tribes located near Class I areas. States should continue working directly with 

tribes on their SIPs and their response to any reasonably attributable visibility impairment 

certification made by an FLM. The EPA believes that it is preferable for states to address tribal 

concerns during their planning process rather than the EPA addressing such concerns in its 

subsequent rulemaking process. During the development of this rulemaking, the EPA was asked 

by the National Tribal Air Association to adopt a requirement that states formally consult with 

tribes during the development of their regional haze SIPs. While we recognize the value of 

dialog between state and tribal representatives, we are not proposing to require it. We note that 

the CAA does not explicitly authorize the EPA to impose such a requirement on the states. 

C. Air Permitting 

One part of the visibility protection program, 40 CFR §51.307, New Source Review , was 

created in 1980 with the rationale that while most new sources that may impair visibility were 

already subject to review under the Prevention of Significant Deterioration (PSD) provisions 

(Part C of Title I of the CAA), additional regulations would “ensure that certain sources exempt 

from the PSD regulations because of geographic criteria will be adequately reviewed for their 

potential impact on visibility in the mandatory Class I Federal area.” 45 FR 80084 (December 2, 

1980). The EPA explained at proposal that this was necessary because the PSD regulations did 

not call for the review of major emitting facilities (or major modifications) located in 
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nonattainment areas,22 and that it was appropriate to “clarify certain procedural relationships 

between the FLM and the state in the review of new source impacts on visibility in Federal class 

I areas.” 45 FR 34765 (May 22, 1980). The EPA envisioned that state and FLM consultation 

would commence with the state notifying the FLM of a potential new source, and that 

consultation would continue throughout the permitting process. We are proposing to revise 

§51.307 only as needed to maintain consistency with revisions to other sections of 40 CFR part 

50 subpart P. 

IV. Proposed Rule Changes 

 The changes being proposed by the EPA will continue steady environmental progress in 

the regional haze program while streamlining its administrative aspects that do not add to 

environmental protection. The EPA has gained a substantial amount of knowledge through the 

process of approving SIPs for the first regional haze implementation period and has learned what 

aspects of the program work well and what aspects should be modified going forward. Feedback 

received from co-regulators during this process has been invaluable in developing this proposal, 

which seeks to reduce administrative burdens of the regional haze program without sacrificing 

 

22 In 1978, PSD rules were put in place that required permitting agencies to interact with FLMs 

and for air quality related values (AQRVs) to be taken into consideration in the PSD permitting 

process. 43 FR 26380 (June 19, 1978). Those PSD rules did not cover sources in nonattainment 

areas, and while there were EPA rules for nonattainment new source review in existence, they 

did not require consideration of Class I areas. In 1979, 40 CFR part 51, appendix S established 

rules for nonattainment permitting, but they did not (and still do not) require consideration of 

visibility or FLM notification. (The same is also true of a more recent addition, 40 CFR 51.165. 

Where applicable to nonattainment areas, this rule does not require Class I reviews. While 40 

CFR 51.165(b) requires that sources located in attainment areas cannot cause or contribute to a 

NAAQS violation anywhere, this does not cover AQRVs in Class I areas.) As a result, in 1980, 

the EPA added requirements to 40 CFR 51.307 for notification of FLMs of pending permits for 

new sources in nonattainment areas. 
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environmental protection. Indeed, the EPA believes that reducing administrative burdens will 

result in a more effective program in terms of achieving the goal of improved visibility. 

A. Clarifications to Reflect the EPA’s Long-Standing Interpretation of the Relationship Between 

Long-Term Strategies and Reasonable Progress Goals.

The EPA is proposing to amend §51.308(f) of the Regional Haze Rule, which contains 

the requirements for comprehensive periodic revisions to regional haze SIPs, by adding new 

provisions that will govern the development of long-term strategies and reasonable progress 

goals in future implementation periods. We are proposing these changes in light of recent 

attempts by commenters and litigants to mischaracterize the existing long-term strategy and 

reasonable progress goal requirements in a way that is detrimental to the visibility program. For 

example, litigants challenging the EPA’s FIP for Arizona and FIPs for Texas and Oklahoma 

have attempted to place primacy on States’ unenforceable reasonable progress goals rather than 

the emission limitations which form the basis of those goals. The EPA’s proposed provisions 

revisions to §51.308(f) are consistent with the EPA’s long-standing interpretation23 of the 

existing regulations at §51.308(d), but are organized in a more logical fashion. While the new 

provisions track the language of the existing regulations at §51.308(d) in many respects, the EPA 

also has proposed changes in certain places to eliminate ambiguities created by the existing 

language and to conform with substantive changes being proposed elsewhere in this rulemaking. 

 

23 The EPA’s interpretation of the proper relationship between a state’s reasonable progress goals 

and its long-term strategy in explained in detail in our proposed action on SIPs from Texas and 

Oklahoma. See section IV.C at 79 FR 74828. This interpretation was reaffirmed in our final 

action on these SIPs. See section II.CB of at [add citation to the final rule for federal 

implementation plans for Texas and Oklahoma, once published. This FR notice currently can be 

viewed at http://www.epa.gov/sites/production/files/2015-12/documents/tx-ok-rh-sip-finaldisapproval-and-fip_disclaimer_signed_.pdf.]81 FR 308 (January 5, 2016).
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In this section, we discuss only those changes that are intended to provide clarity regarding the 

relationship between long-term strategies and reasonable progress goals. Unlike some of the 

provisions discussed in subsequent sections of this preamble, the changes discussed in this 

section do not create new requirements for states. 

Section 51.308(d) of the existing Regional Haze Rule is organized into four subsections: 

(d)(1), concerning the calculation of reasonable progress goals; (d)(2), concerning the calculation 

of baseline and natural visibility conditions; (d)(3), concerning the development of long-term 

strategies; and (d)(4), concerning the development of monitoring strategies. This organizational 

structure does not reflect the actual sequence of steps in the regional haze planning process. For 

example, §51.308(d) lists the requirements for reasonable progress goals before the requirements 

for long-term strategies. In practice, states must evaluate the four statutory factors to select 

emission control measures for their long-term strategies before they can calculate their 

reasonable progress goals by modeling the visibility improvement that will result from the 

implementation of those controls. 

To address this issue and provide clarity to states and other stakeholders, the EPA is 

proposing to organize the requirements in §51.308(f) in a more logical fashion. First, proposed 

subsection (f)(1) provides the requirements governing the calculation of baseline and natural 

visibility conditions, which are necessary to calculate the URP. A state should calculate current 

visibility conditions, the URP and the URP line first. In doing so, the contributions of PM 

species to current anthropogenic light extinction (referred to as the anthropogenic light extinction 

budget) will become evident, which will inform the state’s thinking as to which sources or source 

categories should be evaluated for potential reasonable progress control measures. Second, 

proposed subsection (f)(2) provides the requirements governing the development of long-term 
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strategies. In this step, states must, among other things, evaluate sources that impact visibility at 

one or more Class I areas for potential control measures by considering the four statutory factors. 

Third, proposed subsection (f)(3) provides the requirements governing the calculation of 

reasonable progress goals. Once a state has established emission limitations and other control 

measures as part of its long-term strategy, the state will have the information necessary to model 

the visibility improvement that will result at each Class I area on the 20 percent most impaired 

days and 20 percent clearest days after the long-term strategy has been implemented. The 

projected visibility conditions at the end of the applicable implementation period constitute the 

reasonable progress goals. States must then compare the goals for the Class I area to the URP. If 

the goal for the 20 percent most impaired days is above the URP line, the state must demonstrate 

that there are no additional control measures for sources reasonably anticipated to contribute to 

visibility impairment in the Class I area that are reasonable to include in the long-term strategy. 

(Note this language is intended to be more helpful than the language in the comparable provision 

in §51.308(d)(1)(ii).) Finally, proposed subsection (f)(4) provides the requirements governing 

monitoring strategies, which must be sufficient to allow states to assess the adequacy of their 

long-term strategies going forward. 

In addition to these organizational changes, the EPA is proposing new language in 

§51.308(f)(2) that differs from the existing language in §51.308(d)(3), but is intended to achieve 

the same result. First, the EPA is proposing language in §51.308(f)(2)(i) and (iv) to clarify that 

all states, not just those with Class I areas, must consider the four statutory factors and properly 

document all cost, visibility and other technical analyses when developing their long-term 

strategies. Second, the EPA is proposing language in §51.308(f)(2)(ii) to that requires that states 

must to consider the URP and the measures that contributing states are including in their long-
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term strategies when determining whether the state’s own long-term strategy is sufficient to 

ensure reasonable progress.24 Finally, the EPA is proposing language in §51.308(f)(2)(iii) to 

clarify the respective obligations of “contributing states” and “states affected by contributing 

states,” during interstate consultation. As is the case under the existing rule text, the EPA will 

evaluate the sufficiency of the record developed by each state, the state’s conclusions, and any 

disagreements among states to determine whether the state has used reasoned decision making in 

choosing a set of a control measures that will achieve reasonable progress at the Class I areas 

impacted by the state’s sources. States must document all substantive interstate consultations.

B. Other Clarifications and Changes to Requirements for Periodic Comprehensive Revisions of 

Implementation Plans 

The following clarifications and changes are also proposed to be included in the revised 

§51.308(f).

The URP uniform rate of progress line starts at 2000-2004, for every implementation 

period. The current text of §51.308(d)(1)(i)(B) contains a discussion of how states must analyze 

and determine “the rate of progress needed to attain natural visibility conditions by the year 

2064.” While not actually used within the current rule text, the term that has been commonly 

used to describe this rate is the “uniform rate of progress” or URP. The current text of §51.308(f) 

indicates that states must evaluate and reassess all elements required by §51.308(d), and hence 

the URP, in the second and subsequent implementation periods. Section 51.308(d) is not 

perfectly clear about whether “the rate of progress needed to attain natural visibility conditions 

 

24 The EPA views this as a clarification of the requirement that states with sources affecting a 

given Class I area consult on the content of their long-term strategies. Such consultation would 

be pointless if each state were not meant to consider the other states’ planned emission control 

measures. 
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by the year 2064” is meant to refer to needed progress measured from visibility conditions in the 

baseline period of 2000-2004, or further needed progress measured from “current” visibility 

conditions (i.e., the visibility conditions during a 5-year period ending shortly before SIP 

submission). In other words, the section is not perfectly clear as to whether the glidepath or URP 

line that applies to the SIP for the second or a later implementation period always starts in the 

baseline period of 2000-2004, or in the most recent 5-year period. It is clear that the glidepath or 

URP line then reaches natural visibility conditions in “2064,” but no exact date in 2064 is 

specified. 

To ensure consistent understanding, the EPA is proposing rule revisions to state explicitly 

that in every implementation period, the glidepath or URP line for each Class I area is drawn 

starting on December 31, 2004, at the value of the 2000-2004 baseline visibility conditions for 

the 20 percent most impaired days, and ending at the value of natural visibility conditions on 

December 31, 2064. In this way, it is clear that for a Class I area that has achieved more than the 

URP in the first implementation period, the state can take that into account in its URP analysis 

for the second implementation period. Specifying that the 5-year average baseline visibility 

conditions are associated with the date of December 31, 2004 and that natural visibility 

conditions are associated with the date of December 31, 2064 also clarifies that the period of 

time between the baseline period and natural visibility conditions, which is needed for 

determining the URP (deciviews/year) is 60 years. 
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Note that because of updates to the IMPROVE program, some data values from 2000-

2004 may be revised over time.25 Therefore, the value of the starting point for the URP (i.e., 

baseline visibility conditions) should be re-calculated for purposes of accuracy of analysis in any 

given periodic comprehensive SIP revision. In addition, the value of the baseline visibility 

conditions must be recalculated to be consistent with the approach used for the selection of the 

most impaired days in the SIP revision under preparation (see section IV.C of this document). 

Along with the clarification that the baseline period remains 2000-2004 for subsequent 

implementation periods, the EPA also proposes to include clarifications on how states treat Class 

I areas without available monitoring data or Class I areas with incomplete monitoring data. If 

Class I areas do not have monitoring data for the baseline period, data from representative sites 

should be used. If baseline monitoring data are incomplete, Sstates should use the 5 complete 

years closest to the baseline period (e.g., if a monitor began operating in mid-2000, then 2001-

2005 would be used as the baseline period for the Class I area). The proposed rule text on this 

issue, appearing in §51.308(f)(1)(i), does not appear in the current §51.308(d) because at the time 

§51.308(d) was proposed and finalized, it was not anticipated that this data incompleteness 

situation would exist. We are proposing to add this provision to remove any uncertainty about 

how an issue of data incompleteness should be addressed in a SIP. 

As part of this clarification and to maintain consistency in the reasonable progress goal 

framework, the proposed language in §51.308(f)(3)(i) (and an accompanying definition of “end 

of the applicable implementation period” added to §51.301) would make clear that reasonable 

 

25 IMPROVE data from the 2000-20045 period may be revised after initially reported because of 

more recently revised methods for calculating ambient concentrations from measurements made 

on filters and because of revised methods for filling in missing or invalidated data. Such 

revisions are made in order to maintain consistency in reported results across the years. 
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progress goals are to address the period extending to the end of the year of the due date of the 

next periodic comprehensive SIP revision. Also, proposed §51.308(f)(1)(iv) specifies the end day 

of 2064 as the ending point of the glidepath or URP line.

Visibility conditions on the clearest 20 percent of days must show no deterioration from 

conditions in 2000-2004. The current text of §51.308(d)(1) states that the reasonable progress 

goals must 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. This text is not clear as to whether “the period of the implementation plan” 

refers to the entire period since the baseline period of 2000-2004, or to the specific 

implementation period addressed by the periodic SIP revision. However, a summary table in the 

preamble to the 1999 Regional Haze Rule indicated that the 2000-2004 period would be used for 

“tracking visibility improvement.”26 To avoid any confusion going forward, we are proposing 

new rule text in revised §51.308(f)(3)(i) to make it clear that the baseline for determining 

whether there is deterioration on the 20 percent clearest days is the baseline period of 2000-2004.

Analytical Obligation When the Reasonable Progress Goal for the 20 Percent Most 

Impaired Days Is Not On or Below the URP Line. The EPA is proposing to clarify how the 

comparison of the reasonable progress goal for the 20 percent most impaired days to the rate of 

visibility improvement needed to attain natural conditions by 2064 (i.e., the glidepath or URP 

line) determines the content of the demonstration the state must submit to show that its long-term 

strategy provides for reasonable progress. This clarification appears in the proposed 

§51.308(f)(3)(ii). 

 

26 64 FR 35730 (July 1, 1999).
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The current text of §51.308(d)(1)(ii) discusses required actions of the state containing the 

Class I area should it set a reasonable progress goal that provides for a slower rate of visibility 

improvement than that needed to attain natural conditions by 2064 (i.e., a reasonable progress 

goal for the 20 percent most impaired days that is above the URP line). This section provides that 

in this situation, the state must demonstrate, based on the four reasonable progress factors, that 

the rate of progress for the implementation plan to attain natural conditions by 2064 is not 

reasonable, and that the progress goal adopted by the state is reasonable. To clarify how a state 

must show that being on the URP line is not reasonable in its SIP for the second and subsequent 

regional haze implementation periods, the EPA is proposing in §51.308(f)(3)(ii)(A) that if the 

reasonable progress goal is above the URP line, the state must demonstrate, based on the four 

reasonable progress factors, that there are no additional emission reduction measures for any 

anthropogenic sources or groups of sources in the state that are may be reasonably anticipated to 

contribute to visibility impairment that would be reasonable to include in the long-term strategy.

States must provide a robust demonstration, including documenting the criteria used to determine 

which sources or groups or sources were evaluated and how the four factors were taken into 

consideration in selecting the measures for inclusion in its long-term strategy. 

In existing sections 51.308(d)(2)(iv) and 51.308(d)(3)(i) and (ii), sentences addressing 

obligations of the state with the Class I area and obligations of the contributing state(s) are 

juxtaposed in such a way that it can be confusing for a reader to understand which of the two 

states is being referred each time the word “state” appears. The proposed §51.308(f)(2)(iii) more 

clearly spells out the respective consultation responsibilities of states containing Class I areas as 

well as states with sources that may reasonably be anticipated to cause or contribute to visibility 

impairment in those areas. 
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To clarify and solidify the obligations of what we are referring to as contributing states, 

§51.308(f)(3)(ii)(B) is proposed to specify that in situations where reasonable progress goals are 

set above the glidepath, a contributing state must make the same demonstration with respect to 

its own long-term strategy that is required of the state containing the Class I area, namely that 

there are no other measures needed to provide for reasonable progress. This provision will ensure 

that states perform rigorous analyses, and adopt measures necessary for reasonable progress, 

with respect to Class I areas that their sources contribute to, regardless of whether such areas are 

physically located within their borders. 

Emission inventories. The proposed language of §51.308(f)(2)(iv) regarding the baseline 

emissions inventory to use in developing the technical basis for the state’s long-term strategy 

would reconcile this section with changes that have occurred to 40 CFR part 51, subpart A, Air 

Emissions Reporting Requirements, since the Regional Haze Rule was originally promulgated in 

1999. The proposed changes also would provide flexibility in the base inventory year the state 

chooses to use, as the EPA has always intended if there is good reason to use another inventory 

year. 

EPA action on reasonable progress goals. Proposed language in §51.308(f)(3)(iv) would 

make clear that in approving a state’s reasonable progress goals, the EPA will consider the 

controls and technical demonstration provided by a contributing state with respect to its longterm strategy, in addition to those developed by the state containing the Class I area with respect 

to its long-term strategy. This section is a clarification of §51.308(d)(1)(iii), which only 

explicitly mentions the demonstration provided by the state containing the Class I area. 

Progress reports. Finally, proposed language in §51.308(f)(5) complements proposed 

changes regarding progress reports and the proposal to eliminate separate progress reports being 
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due simultaneously with periodic comprehensive SIP revisions. This language would require the 

periodic comprehensive SIP revision to include certain items of information that would have 

been addressed in the progress report, thereby expanding its scope somewhat. While the state 

would no longer need to prepare and submit two separate documents at the same time (the 

periodic comprehensive SIP revision and a progress report), the same information would still be 

covered. Combining requirements in this way will avoid the overlap in content that would occur 

with two separate documents.

Smoke management programs and basic smoke management practices. The proposed 

§51.308(f)(2)(vi)(E) mirrors the existing §51.308(d)(3)(v)(E) with updates to reflect terminology 

used within the air quality and land management communities to clarify and promote a common 

understanding of this provision. We propose to replace the term “smoke management 

techniques” in §51.308(d)(3)(v)(E) with “basic smoke management practices.” We propose to 

replace the term “forestry management purposes” with “wildland vegetation management 

purposes” in recognition that not all wildland for which fire and smoke are issues is forested. We 

also propose to replace the phrase “plans” with “smoke management programs for prescribed 

fire.” Like §51.308(d)(3)(v)(E), the proposed §51.308(f)(2)(vi)(E) would require states to 

consider only currently existing smoke management programs (formerly referred to as “plans”). 

Section IV.E discusses wildland fire-related issues in more detail and includes explanations of 

the terms “basic smoke management practices” and “smoke management program.”

C. Changes to Definitions and Terminology Related to How Days Are Selected for Tracking 

Progress 

Section 51.308(d) of the existing Regional Haze Rule requires states to determine the 

visibility conditions (in deciviews) for the average of the 20 percent least impaired and 20 
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percent most impaired visibility days over a specified time period at each of their Class I areas. 

Section 51.301 of the Regional Haze Rule defines visibility impairment as the humanly 

perceptible change in visibility from that which would have existed under natural conditions. 

This definition of visibility impairment suggests that only visibility impacts from anthropogenic 

sources should be included when considering the degree of visibility impairment. However, the 

preamble to the 1999 final rule stated that the least and most impaired days were to be selected as 

the monitored days with the lowest and highest actual deciview levels, respectively. 64 FR 35728 

(July 1, 1999). The interpretation in the preamble was subsequently reflected in the EPA 

guidance on setting reasonable progress goals and tracking progress. In practice, in their SIPs for 

the first implementation period states followed the approach described in the 1999 preamble and 

the subsequent guidance, and the EPA approved the SIPs with respect to that aspect. However, as 

described later, experience now indicates that for the most impaired days an approach focusing 

on anthropogenic impairment in particular is more appropriate going forward. We are not 

proposing to change the approach of using the 20 percent of days with the best visibility to 

represent good visibility conditions for reasonable progress goal and tracking purposes, but we 

are proposing text changes to accurately describe how those days are to be selected. These days 

would be referred to as the 20 percent clearest days. 

Natural contributions to the total actual deciview levels vary from year to year. In order 

to minimize interannual variability, the Regional Haze Rule uses 5-year averages for determining 

the baseline and current visibility conditions. Also, under the EPA’s modeling guidance for 

regional haze SIPs, reasonable progress goals are projected starting from the average of visibility 

conditions in a 5-year period that is centered around (or at least includes) the year of the base 

emission inventory used in the air quality modeling process. Now that many visibility monitoring 
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sites have at least 15 years of data, it is clear that in some locations 5-year averages are not long 

enough to dampen the visibility impacts of occasional extreme fire years. In their SIPs and SIP 

revisions for the first implementation period, some states explained that the 20 percent most 

impaired days in certain Class I areas can be dominated by uncontrollable visibility impacts. 

Many states, particularly western states, have urged the EPA to make rule changes that would 

allow them to track visibility progress in Class I areas using a method that is more closely linked 

with visibility impacts from controllable emissions. 

To help states minimize the impacts of uncontrollable emissions on visibility tracking, 

the EPA proposes to more explicitly (and consistently) address this issue for future 

implementation periods. In general, the proposed changes related to the selection of days for 

visibility tracking are intended to accomplish the following for future implementation periods: 

(1) clarify that “visibility impairment” means the deviation from natural visibility and therefore 

is due to anthropogenic impacts, (2) revise definitions in §51.301 to make clear that the 20 

percent most impaired days should be selected based on anthropogenic visibility impairment 

rather than based on the days with highest deciview values due to impacts from all types of 

sources, and (3) continue to use the 20 percent of days with the lowest total deciviews (i.e., 

“clearest days”) rather than the 20 percent least impaired days for purposes of tracking any 

adverse trend in visibility on clear days. 

The definitions in §51.301 for several terms and phrases related to the selection of days 

for visibility tracking have been clarified in the proposed revisions of the rule text. Definitions 

that are proposed to be changed slightly to provide more clear explanations of their meanings 

include the following: deciview, most impaired days, and visibility impairment. 
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Additionally, we propose definitions for the following previously undefined terms be 

included in §51.301: clearest days, the deciview index (the term was deciview haze index in the 

1999 Regional Haze Rule), natural visibility conditions and visibility. We propose the addition of 

the term clearest days to unambiguously describe the days with the lowest actual deciview 

values, for which there is to be no degradation in visibility.

27

. We propose changing the deciview 

haze index to the deciview index to remove the word haze, since the deciview index can be used 

for visibility impairment as well as for the total effect of all sources.28 Visibility was previously 

undefined although used in the definitions of several other important terms, and so we have 

added a proposed definition to describe that visibility is the change in optical clarity when 

viewing objects at a distance. We also propose adding a definition for natural visibility 

conditions to clarify that natural visibility conditions cannot be measured and must be inferred or 

estimated, and to distinguish the visibility conditions that occur due to natural conditions from 

natural conditions themselves such as humidity, emissions from natural sources, etc. 

Given the current Regional Haze Rule’s definitions of most impaired days and visibility 

impairment, the regulations could be read to direct states and the EPA to use the days with the 

most perceptible anthropogenic impairment as the 20 percent most impaired days. The proposed 

changes to these definitions in §51.301 do not change this direction. The EPA solicits comments 

on a first proposal, fully reflected in the proposed rule text, which would require that states select

 

27 We are not proposing to remove the definition of least impaired days because it will still apply 

to the first implementation period (including the SIPs and progress reports covering the first 

implementation period). 

28 We note that the very definition of “regional haze” refers to “impairment,” making it 

confusing to use “haze” to refer to the actual level or degree of visibility considering the effects 

of both natural and anthropogenic sources. Our proposed edits are aimed at avoiding any 

inconsistent use of the term “haze.” 
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the 20 percent most impaired days based on anthropogenic impairment, rather than based on the 

highest deciview values due to all sources affecting visibility. If this approach is finalized, states

would still have the option to also present the visibility data using the current approach based on 

the days with the highest overall deciview index values (i.e., the 20 percent haziest days). 

Including this information in the SIP may help communicate to the public the magnitude of 

impacts from natural sources including wildland wildfires and dust storms, and thus the utility of 

the change in approach. Under this first proposal, the reasonable progress goals and URP line 

that are calculated using anthropogenic impairment to select the most impaired days will be the 

glidepath that is used to trigger the requirement for a state to show that it is not reasonable for the 

SIP to provide for the rate of progress that would be needed to reach natural visibility conditions 

in 2064 (see section IV.B of this document). 

The EPA seeks comment also on a second, alternative proposal under which the final rule 

would allow each state with a Class I area to choose between using the revised approach 

described earlier (using the 20 percent most anthropogenically impaired days) and using the 20 

percent haziest days (whether dominated by natural or anthropogenic impacts) to track visibility 

as all states with Class I areas did in the first regional haze SIPs. (This alternative approach is not 

laid out in proposed rule text revisions, but only minor edits would be required to implement it in 

the final rule.) If the final rule takes this approach, states would still have the option to also 

present the visibility data using the other approach. 

In summary, the EPA seeks comment on two approaches for selecting the 20 percent 

“worst” days from the IMPROVE monitoring data, only one of which (or possibly another 

approach suggested in public comments) would be incorporated into the final rule. In the first 

approach, states would be required to select the 20 percent most impaired days, i.e., the days 
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with the most impairment from anthropogenic sources. This first approach would be a change 

from the approach states used in the first implementation period. This first approach would also 

mean that all states would use a framework that is consistent on this aspect. In the second 

approach, states would be allowed to choose whether to select the 20 percent of days with the 

highest overall haze (i.e., the approach used in the first implementation period) or to select the 20 

percent of days with the most impairment from anthropogenic sources. The EPA will consider 

comments received on these two options or additional options offered by commenters. 

If the 20 percent most anthropogenically impaired days are used to estimate natural 

visibility conditions, current visibility conditions and the uniform rate of progressURP, they must 

also be used in setting reasonable progress goals and in progress reports. Conforming edits are 

being proposed to the provisions related to each of these, for that purpose. If the final rule 

requires the revised approach described earlier in the first proposal, it would apply starting with 

the second and subsequent periodic comprehensive SIP revisions and then to progress reports 

submitted after the second SIP revision. There would be no change with respect to the EPA 

action on SIP revisions for the first implementation period. 

In order to select the 20 percent most impaired days based on the days with the most 

anthropogenic impairment, natural contributions to daily deciview values must be estimated by 

some method. This in turn requires measured concentration values for PM components to be 

allocated to natural versus anthropogenic sources. The EPA is not proposing that any particular 

method for determining natural contributions to daily haze and thus the degree of visibility 

impairment for each monitored day be codified in the rule text. The EPA plans to issue guidance 

describing a recommended approach along with a process for routinely providing relevant 

datasets for use by states when they develop their SIPs and progress reports. Because no 
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particular method would be prescribed by rule, states could develop, justify and use another 

method in their SIPs, if the final rule requires (or allows) the 20 percent most impaired days 

based on anthropogenic impairment to be used. 

D. Impacts on Visibility from Anthropogenic Sources Outside the U.S. 

 

The EPA acknowledges that emissions (natural and anthropogenic) from other countries 

(and from marine vessel activity in non-U.S. waters) may impact Class I areas, especially those 

areas near borders and coastlines. We have had requests from states with such Class I areas that 

given these emissions are beyond states’ control, the states should be allowed to account for 

international impacts when preparing SIPs and progress reports. For example, states have 

requested that they be allowed to consider impacts from international emissions when comparing 

their reasonable progress goals to the URP line. This comparison matters because (as described 

in section IV.C) it may trigger an additional analytical requirement by the state. Impacts from 

international emissions can also affect whether a progress report will conclude that actual 

visibility conditions are approaching the reasonable progress goals for the end of the 

implementation period. It has been suggested to the EPA that estimated impacts from 

international emissions might be added to the 2064 end point of the URP line. It has also been 

suggested that estimated impacts from international emissions be subtracted from baseline and 

current visibility conditions. 

On this issue, we first wish to clarify that it has never been the intention of the EPA that 

states be obligated to in any way compensate for haze impacts from international emissions by 

adopting more stringent emission controls on their own sources. We also wish to note that 

impacts from natural sources in other countries should be considered part of natural visibility 

conditions. States have the flexibility under the Regional Haze Rule to justify and use values for 
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natural visibility conditions that include such effects. We believe the proposed changes regarding 

which days in a year are used for tracking progress (see section IV.DC), when supplemented by 

our planned guidance on this topic, will adequately address international impacts related to 

significant wildland wildfires in Canada and Mexico and dust storms in Mexico (and perhaps 

also dust storms in northern Africa). 

The EPA has further considered possible approaches regarding the impacts from 

anthropogenic sources in other countries, including border countries as well as more distant 

countries such as China. It is the role of the federal government, much more than of the states, to 

work with other countries to make such reasonable progress. The EPA is, in fact, actively 

engaged with other countries to help them reduce their anthropogenic emissions, particularly 

emissions in Mexico from sources near the U.S.-Mexico border. See

http://www2.epa.gov/border2020. 

We believe that it may be appropriate to allow states to adjust the reasonable progress 

goal framework, including their progress reports, to explicitly take into account international 

impacts from anthropogenic sources, but only when and if these impacts can be estimated with 

sufficient accuracy. We do not believe that explicit consideration of impacts from anthropogenic 

sources outside the U.S. would actually affect the conclusions that states should make about what 

emission controls for their own sources are needed for reasonable progress. Even so, explicit 

quantification of international impacts, if accrurate, could improve public understanding and 

effective participation in the development of regional haze SIPs. Also, taking international 

impacts into account in some cases may affect whether a state (and contributing states) are 

subject to the requirement of proposed §51.308(f)(3)(ii) regarding a demonstration that there are 

not additional emission reduction measures needed for reasonable progress. However, we are not 
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convinced that such impacts can be estimated with sufficient accuracy at this time, in part due to 

great uncertainty about past, present and future emissions from sources in most other countries. 

However, it may be that by the time some future periodic comprehensive SIP revisions are to be 

prepared, for some states possibly as early as when they are preparing their second SIP, methods 

and data for estimating international impacts will be substantially more robust. 

Therefore, the EPA is requesting comment on whether the final rule should contain a 

proposed provision that would allow states with Class I areas (and those states with sources 

contributing to Class I areas) significantly impacted by international emissions to make an 

adjustment to the URP with specific approval by the Administratorincorporate this information 

into the reasonable progress goal framework for their regional haze SIPs.

29 The adjustment 

would consist of adding to the value of natural visibility conditions an estimate of international 

 

29 This information in concept might be incorporated into the reasonable progress goal 

framework in two ways, and possibly other ways also, if valid methods for doing so were 

available. The analysis of IMPROVE monitoring data to develop the estimate of “current 

conditions” could include steps to remove the influence of emissions from anthropogenic sources 

outside the U.S.; for consistency, projected RPGs would then also exclude such influence. Or, 

the 2064 end point of the URP line could be increased by the estimated amount of this influence, 

such that it represents true natural conditions plus the influence of emissions from such sources. 

At this time, the EPA is not proposing a specific approach to incorporation of this information, 

but rather is seeking comment on including in the final rule a provision that would allow the 

Administrator to approve a state’s proposed approach to such incorporation on a case-by-case 

basis. 
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impacts, only for the purpose of calculating the URP.30 We believe that this adjustment should be 

permitted only if the international impacts have been estimated with methods and data approved 

by the Administrator as sufficiently reliable for that purpose and if the exact manner in which the 

information is incorporated into the reasonable progress goal framework is logical and consistent 

with the purposes of the CAA and the Regional Haze Rulescientifically valid. We are not 

proposing specific rule text for this purpose in §51.308(f)(1)(vi). In addition, we are proposing 

small rule text changes in §51.308(f)(1)(i) and (vi) (compared to their counterparts in 

§51.308(d)) to remove “needed to attain natural visibility conditions” from the reference to 

“uniform rate of progress,” because when adjusted to reflect international impacts the “uniform 

rate of progress” would not be the rate of progress that would reach true natural visibility 

conditions. Because the manner in which a state with a Class I area calculates the URP may 

affect other states with sources that contribute to visibility impairment at the Class I area,31 we 

recommend that a state seeking approval for such an adjustment first consult with contributing 

states. Such an adjustment would also be a topic for the required consultation with the FLM for 

the Class I area at issue. We welcome suggestions for specific comments on this proposed rule 

 

30 As another possible approach to accounting for international impacts, the analysis of 

IMPROVE monitoring data to develop the estimates of 2000-2004 baseline visibility conditions 

could include steps to remove the influence of emissions from anthropogenic sources outside the 

U.S. The calculation of the URP would be based on this adjusted estimate of baseline visibility 

conditions (see “The uniform rate of progress line starts at 2000-2004, for every implementation 

period” in section IV.B) and the true value of natural visibility conditions. Also, for consistency, 

the values for current visibility conditions and for the projected RPG would exclude the 

influence of international emissions. We invite comment on this alternative approach, which we 

may include in the final rule as the only allowed approach or as another allowed approach.

31 Contributing states may be affected because under proposed §51.308(f)(3)(iv)(B), a 

contributing state may have an additional analytical requirement if the RPG does not provide for 

the URP at an affected Class I area in another state. 
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text as well as comments in general support or opposition to this concept, noting that the EPA 

may or may not finalize this portion of the proposal.

E. Impacts on Visibility from Wildland Fires Within the U.S. 

Fires on wildlands within the U.S. can significantly impacts visibility in some Class I 

areas on some days and have lesser impacts on a greater number of days. Accordingly, we 

discuss here whether measures to reduce emissions from wildland wildfire and wildland 

prescribed fires may be needed for reasonable progress towards natural visibility conditions. 

Similar to transported emissions from other countries discussed in section IV.D, we also discuss 

whether smoke from fires might cause the projected RPG to be above the URP line, thus 

triggering the additional analytical requirement (discussed in section IV.B) to show that there are 

no additional measures that are necessary for reasonable progress. We are proposing rule 

language to allow the Administrator to approve a state’s proposal to adjust the URP to avoid 

subjecting a state to this additional analytical requirement due only to the impacts of specific 

types of wildland fire. Before presenting this proposal, we provide background on wildland fire 

concepts. This section does not address and does not apply to fires of any type on lands other 

than wildland or to burning on wildland that is for purposes of commercial logging slash disposal 

rather than wildland ecosystem health and public safety. 

Background on wildland fire. Fires on wildland play an important ecological role across 

the globe, benefiting those plant and animal species that depend upon natural fires for 
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propagation, habitat restoration and reproduction. Wildland can include forestland,32 shrubland,33

grassland34 and wetlands.35 Fires on wildland can be of two types: wildfire (unplanned) and 

prescribed fire (intentionally ignited for management purposes including ecosystem health and to 

reduce the risk of catastrophic wildfires). The EPA anticipates that wildfires will become more 

frequent on wildlands in the future due to the natural accumulation of fuels in the absence of fire, 

and due to climate change that is leading to increased incidence of wildfire,36 which may 

necessitate land managers employing prescribed fire more frequently to manage fuel loads and 

achieve other benefits as described below.37, 38 

Wildfire emissions account for a large portion of direct PM2.5 emissions 

nationally and can contribute to periodic high levels of PM2.5 and PM10 levels which reduce 

visibility. Wildfires also emit volatile organic compounds and NOx, which are precursors to 

 

32 Forestland is land on which the vegetation is dominated by trees or, if trees are lacking, the 

land shows historic evidence of former forest and has not been converted to other uses. 

Definition available at https://globalrangelands.org.

33 Shrubland is land on which the vegetation is dominated by shrubs. Definition available at 

https://globalrangelands.org/rangelandswest/glossary.

34 Grassland is land on which the vegetation is dominated by grasses, grass like plants, and/or 

forbs. Definition available at https://globalrangelands.org/rangelandswest/glossary.

35 Wetlands, as defined in 40 CFR 230.3(t), means those areas that are inundated or saturated by 

surface or ground water at a frequency and duration sufficient to support, and that under normal 

circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil 

conditions. Wetlands generally include swamps, marshes, bogs and similar areas. 

36 The Administrator’s finding on the adverse effects of greenhouse gases included the 

observation that wildfires have increased, and that there are potential serious adverse impacts 

from further wildfire occurrence. 74 FR 66530 (December 15, 2009). 

37 Climate Change in the United States: Benefits of Global Action, U.S. EPA, EPA–430–R–15–

001, June 2015. Available at http://www2.epa.gov/cira.

38 The National Strategy: The Final Phase in the Development of the National Cohesive 

Wildland Fire Management Strategy, Report to Congress developed by the U.S. Department of 

Agriculture and the U.S. Department of the Interior, April 2014. Available at 

http://www.forestsandrangelands.gov/strategy/thestrategy.shtml.
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PM2.5 and PM10 (and to ozone, which does not affect visibility). Besides their effect on air 

quality, wildfires pose a direct threat to public safety. Changes in wildfire risk and occurrence 

are closely associated with the lack of periodic fire in fire-dependent ecosystems, demographic 

changes and associated infrastructure investment at the margins of wildland and, as already 

noted, climate change and climate variability. The threat from wildfires can be mitigated through 

management of wildland vegetation. Attempts to suppress wildfires have resulted in unintended 

consequences, especially the buildup of fuel loads, which can create a lingering fire liability that 

will eventually find resolution, unplanned or planned. Unplanned fires in areas with high fuel 

loads present high risks to both humans and ecosystems.39 Planned prescribed fires and letting 

some wildfires proceed naturally (typically those with lower fire intensity and severity) are tools 

that land managers can use to reduce fuel load, unnatural understory and tree density, thus 

helping to reduce the risk of catastrophic wildfires. Allowing some wildfires to continue to burn 

even though they could be suppressed and the thoughtful use of prescribed fire can influence the 

occurrence, size and severity of catastrophic wildfires, which may lead to improved public 

safety, improved protection of property and an overall reduction in fire-induced smoke impacts 

on visibility and subsequent health effects. Thus, appropriate use of prescribed fire may help 

manage the contribution of wildfires to both background and peak PM (and ozone) air pollution. 

However, prescribed fires themselves can affect visibility in Class I areas. Wildfires tend to 

occur in the summer when conditions for wildfire are favorable. Land managers tend to conduct 

 

39 Indeed, ‘‘fire policy that focuses on [wildfire] suppression only, delays the inevitable, 

promising more dangerous and destructive future . . . fires.’’ Stephens, SL; Agee, JK; Fule, PZ; 

North, MP; Romme, WH; Swetnam, TW. (2013). Managing Forests and Fire in Changing 

Climates. Science 342: 41–42. 
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prescribed fires at other times to reduce the risk of a prescribed fire escaping during favorable 

wildfire conditions in the summer. There are, of course, exceptions to this seasonal pattern. 

In addition to reducing wildfire risks to humans and ecosystems and wildfire 

contributions to air pollution including poor visibility, prescribed fires can have benefit s to those

plant and animal species that depend upon natural fires for propagation, habitat restoration and 

reproduction, as well as benefits to a myriad of ecosystem functions (e.g., carbon sequestration, 

maintenance of water supply systems and endangered species habitat maintenance). The EPA 

understands the importance of prescribed fire, which mimics a natural process necessary to 

manage and maintain fire-adapted ecosystems and climate change adaptation, while reducing 

risk to public safety and the risk of uncontrolled emissions and ecosystem damage from 

catastrophic wildfires. The EPA is committed to working with FLMs, other federal agencies, 

tribes, states and private landowners to effectively manage prescribed fire use to reduce the 

impact of catastrophic wildfire-related emissions on PM10 and PM2.5 (and ozone). 

Basic smoke management practices are types of actions that the manager of a prescribed 

fire can take to reduce the amount of smoke generated by a prescribed fire and/or to reduce 

public exposure to the smoke that is generated. These practices are described in more detail in a 

publication issued by federal agencies that use prescribed fire as part of their land management 

programs.40 While we are not proposing to define basic smoke management practices within the 

Regional Haze Rule, we are providing as guidance, in Table 1, a summary of six common basic 

smoke management practices. 

 

40 USDA Forest Service and Natural Resources Conservation Service, Basic Smoke Management 

Practices Tech Note, October 2011, 

http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1046311.pdf 
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Table 1 - Summary of Basic Smoke Management Practices, benefit achieved with the 

practice, and when it is applieda 

Basic Smoke 

Management Practice

Benefit achieved with the 

BSMP

When the BSMP is Applied 

– Before/During/After the 

Burn

Evaluate Smoke Dispersion 

Conditions. 

Minimize smoke impacts. Before, During, After. 

Monitor Effects on Air 

Quality. 

Be aware of where the smoke is 

going and degree it impacts air 

quality. 

Before, During, After. 

Record-Keeping/Maintain 

a Burn/Smoke Journal. 

Retain information about the 

weather, burn and smoke. If air 

quality problems occur, 

documentation helps analyze and 

address air regulatory issues. 

Before, During, After. 

Communication – Public 

Notification. 

Notify neighbors and those 

potentially impacted by smoke, 

especially sensitive receptors. 

Before, During. 

Consider Emission 

Reduction Techniques. 

Reduceing emissions through 

mechanisms such as reducing 

fuel loading can reduce 

downwind impacts. 

Before, During, After. 

Share the Airshed – 

Coordination of Area 

Burning. 

Coordinate multiple burns in the 

area to manage exposure of the 

public to smoke. 

Before, During, After. 

a

 Elements of these BSMP could also be beneficial to apply to wildfires for areas likely to experience 

recurring wildfires. 

The term “smoke management program” is not currently defined in the Regional Haze 

Rule. At the time of the 1999 Regional Haze Rule, the term was generally used to mean a 

framework that included (i) authorization to burn, (ii) minimizing air pollutant emissions, (iii) 

smoke management components of burn plans, (iv) public education and awareness, (v) 

surveillance and enforcement and (vi) program evaluation. We believe this usage of the term is 

still appropriate. By “authorization to burn,” we mean that a government authority restricts 

where, when and/or by whom a prescribed fire may be conducted. The proposed 

§51.308(f)(2)(v)(E) would make a certain state obligation depend on whether a “smoke 
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management program” currently exists within a state. See “Consideration of control measures 

for wildland prescribed fire” in this section for further discussion of this point. 

We do not consider the term smoke management program for the purposes of 

§51.308(f)(2)(v)(E) to mean programs that includes only seasonal restrictions on burning 

because of fire safety concerns, voluntary educational programs designed to raise air quality 

awareness of potential prescribed fire users, voluntary programs in which land managers agree to 

coordinate their prescribed fire activities but are free to withdraw from the program at any time 

or some combination of the above. The EPA supports these latter types of programs, but we do 

not believe it is appropriate to have the obligation in §51.308(f)(2)(v)(E) triggered by the 

existence of these types of programs.41

The recently proposed revisions to the Exceptional Events Rule would clarify that in the 

context of the regulatory programs for the protection of the NAAQS, (i) wildland wildfires are 

natural events and prescribed fires are anthropogenic events; (ii) a wildland wildfire is not 

controllable or preventable (in the sense that generally it would not be reasonable to expect 

efforts at prevention of occurrence and/or control of emissions to have gone beyond the efforts 

actually made for a given wildfire by responsible land managers and fire safety officials); (iii) a 

prescribed fire is not reasonably controllable (in the sense that it would not have been reasonable 

 

41 If a state has one or more programs of these latter types in existence at the time it submits its 

periodic SIP revision but a smoke management program with the six distinguishing elements 

does not exist in the state at that time, then with respect to prescribed fire as a cause of visibility 

impairment the state would be required only to consider basic smoke management practices and 

to meet the requirements of §51.308(f)(2) that generally apply when a state considers additional 

measures for emission sources of any type. We note that the determining factor is the existence 

of a program or programs and their elements, not whether the program or programs have been 

incorporated into the SIP as enforceable measures or described in the narrative portion of the 

SIP. 
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to do more to control its emissions) if it was conducted in accordance with a state-certified 

smoke management plan or if the burn manager has employed appropriate basic smoke 

management practices; and (iv) a prescribed fire is presumptively not reasonably preventable (in 

the sense that it not would have been reasonable to not conduct it, because of the multiple 

important benefits that would have been foregone) if a multi-year land or resource management 

plan42 for a wildland area has a stated objective to establish, restore and/or maintain a sustainable 

and resilient wildland ecosystem and/or to preserve endangered or threatened species through a 

program of prescribed fire and the use of prescribed fire in the area has not exceeded the 

frequency indicated in that plan. Today’s proposed revisions to the Regional Haze Rule do not 

include language to these same four effects because the Regional Haze Rule does not contain this 

level of specificity with respect to any source type. However, we do believe these same 

propositions apply in the regional haze context, and the remainder of this section is based on 

these propositions. We invite comment on these propositions, and on whether it is appropriate to 

include in the final rule explicit language reflecting them. 

Wildland Wildfires

As natural events, two issues are associated with wildfires on wildland. The first is 

whether and how a state is obligated to consider measures which could reduce emissions from 

these wildfires. The second issue is the one identified at the start of this section, namely the 

possible impact of wildland wildfires on whether the RPG is above the URP line and thus 

whether a state is subject to the additional analytical requirement described section IV.B. 

 

42 These plans could also include State Forest Action Plans, fire management plans, prescribed 

fire on wildland management plans, landscape management plans or equivalent public planning 

documents.
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Consideration of control measures for wildland wildfires. Because wildland wildfires are 

considered natural events, emissions from wildfires are natural emissions that contribute to 

natural reductions in visibility. Thus, states are not obligated to consider whether measures to 

reduce emissions from wildfires are necessary for reasonable progress towards natural visibility 

conditions. However, we encourage states to consider how use of prescribed fire may reduce the 

frequency, geographic scale and intensity of natural wildfires, such that vistas in Class I areas 

will be clearer on more days of the year, to the enjoyment of visitors. We believe appropriate use 

of prescribed fire needed for ecosystem health and to protect life and property from wildfires, 

with basic smoke management practices applied, should be encouraged by EPA rules and 

policies, and that potentially unnecessary barriers to its use should be reassessed by the 

responsible authorities with input from land managers, affected communities and stakeholders. 

Possible effect on the comparison of the RPG to the URP line. Because wildland 

wildfires are natural events, emissions from wildland wildfires do not contribute to “visibility 

impairment” given that this term refers only to reductions in visibility attributable to 

anthropogenic sources. Under the proposed approach of basing RPGs on the 20 percent most 

impaired days, we expect that days with large impacts from wildland wildfires will not be 

included in the set of days selected as the 20 percent most impaired days in each year.43 Thus, we 

expect that wildland wildfires with notable effects on visibility will not be a reason why a 

projected RPG for the 20 percent most impaired days would be above the URP line, simply 

 

43 We intend to recommend an approach to identifying the 20 percent most impaired days that 

uses the ambient concentration of carbon-containing material to separate total light extinction 

between natural sources, including wildfires, and anthropogenic sources. A day strongly affected 

by wildfire will have high concentrations of carbon-containing material and a very large fraction 

of light extinction will be attributed to natural causes, thus the day likely will not be one of the 

20 percent most impaired days. 
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because the URP line will be about visibility on other types of days. Thus, we expect that 

wildland wildfires will not affect whether a state becomes subject to the additional analytical 

requirement to show that there are no additional measures that are necessary for reasonable 

progress. Also, we expect that the 20 percent clearest days (selection of which is based on 

visibility as affected by all types of sources) will not include any days with notable effects from 

wildland wildfires. Thus, we expect that wildland wildfires will not affect whether a state is able 

to demonstrate that there is no deterioration in visibility on the 20 percent clearest days, which is 

a requirement for SIP approval. 

Wildland Prescribed Fires 

As anthropogenic events, two issues are associated with prescribed fires on wildland. The 

first is whether and how a state is obligated to consider measures which could reduce emissions 

from these prescribed fires. The second issue is the possible impact of wildland prescribed fires 

on whether the RPG is above the URP line. 

Consideration of control measures for wildland prescribed fire. Under existing 

§51.308(d)(2)(i) and proposed revised §51.308(f)(2)(v), a state is required to identify all 

anthropogenic sources of visibility impairment considered by the state in developing its longterm strategy and the criteria used to select the sources for which additional emission reduction 

measures were considered in light of the four reasonable progress factors. Existing 

§51.308(d)(3)(v)(E) more specifically requires a state to consider “smoke management 

techniques for agricultural and forestry management purposes including plans as currently exist 

within the State for these purposes.” As explained in section IV.B, in carrying this paragraph 

forward into the revision of §51.308(f) that will make it free standing, we are proposing to 

update some of the terminology and to require states to consider “basic smoke management 
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practices for prescribed fire used for agricultural and wildland vegetation management purposes 

and smoke management programs as currently exist within the state for these purposes.” 

Taken together, we interpret these provisions to mean that every state must consider 

whether wildland prescribed fires contribute to impairment at their own Class I areas or Class I 

areas in other states. If they do not contribute to any meaningful degree, the SIP may take note of 

this and thereby satisfy both provisions. If prescribed fires in a state contribute meaningfully to 

impairment at a Class I area, the state is required to consider basic smoke management practices 

for prescribed fires in the development of its long-term strategy, regardless of whether or not 

those practices are currently being implemented, required by state law or mandated by an EPAapproved SIP. The state would be required to consider only smoke management programs as 

currently exist within the state.44 We believe that the state should in this situation give new 

consideration to the effectiveness of its smoke management programs in protecting air quality 

while also allowing appropriate prescribed fire for ecosystem health and to reduce the risk of 

catastrophic wildfires. The state could also consider the implementation of a new smoke 

management program. 

We would like to make clear that taken together, these two provisions do not necessarily 

require any state to “select” wildland prescribed fire (under §51.308(f)(2)(v)) as an 

anthropogenic source of visibility impairment for which it must consider and analyze emission 

reduction measures (such as a smoke management program and basic smoke management 

practices) based on the four reasonable progress factors listed in §51.308(f)(2)(i). Thus, a state is 

 

44 We interpret “currently exist” in both referenced sections of the Regional Haze Rule to refer to 

programs that are operational as of the SIP due date, not the date the Regional Haze Rule was 

promulgated.
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not necessarily required to develop cost estimates for smoke management programs or basic 

smoke management practices. However, if a state does not “select” wildland prescribed fire as a 

source for four-factor analysis, it must explain why it has not. As previously stated, the 

explanation may be as simpley as taking note that prescribed fires do not make a meaningful 

contribution to visibility impairment at in-state and nearby Class I areas. Where prescribed fires 

are more important, it may be sufficient for the SIP revision to explain the role of properly 

planned and managed wildland prescribed fire as described in this section, the state’s ongoing 

smoke management programs, if any, and the current and possibly increased future use of basic 

smoke management practices by federal, state, local and private land managers, but not to 

“select” wildland prescribed fire as a source category for four-factor analysis. 

If a state does “select” wildland prescribed fire as a source for four-factor analysis, the 

state must conclude this analysis by determining whether additional measures to reduce 

emissions from wildland prescribed fire are necessary for reasonable progress. Any such 

measures must be included in the long-term strategy. Because some of the basic smoke 

management practices are difficult to describe with the specificity needed to make them 

practically enforceable, it may not be appropriate to conclude that a SIP requirement for the use 

of each practice is necessary for reasonable progress. For example, one basic smoke management 

practice is to monitor the effects on air quality due to the smoke plume from a prescribed fire. 

“Monitoring” could include ground-based visual observations, aircraft observations, 

meteorology-based modeling, fixed or portable air quality monitoring stations, hand-held 

monitors, etc. Because the most appropriate monitoring approach is often situation- and 

resource-specific, mandating a specific approach is inadvisable. Further, requiring a prescribed 

fire manager to document that a required monitoring approach was used could distract resources 
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from managing the prescribed fire and communicating with potentially affected members of the 

public. Therefore, a SIP commitment for a state or local agency to promote the use of basic 

smoke management practices could be more desirable than a SIP requirement for land managers 

to use each basic smoke management practice.

Although not required to select prescribed fires as a source category subject to four-factor 

analysis, if the state elects to do so, then given the benefits of prescribed fires including the 

reduction they can achieve in visibility-obscuring smoke from wildfires, a state may determine 

that reasonable progress does not require implementation of a new smoke management program, 

or it may adopt a smoke management program. We recommend that in either case, the smoke 

management program should be designed so that it does not inappropriately restrict prescribed 

fires with these benefits. If a state determines that compliance with a smoke management 

program of a particular design is required for reasonable progress, then the state must include the 

smoke management program in the SIP as part of the long-term strategy. We believe that states 

can include sufficiently detailed, enforceable language in their smoke management programs to 

make them practicably enforceable for SIP purposes (as may not be the case for all basic smoke 

management practices). We recommend that a smoke management program that is made part of 

the long-term strategy not impose unnecessary barriers to prescribed fire use on wildland for 

ecosystem health and safety purposes. One of the distinguishing elements of a smoke 

management program is a provision for periodic program evaluation. We recommend that every 

smoke management program include a plan for this periodic assessment by the responsible 

authorities that provides for input from land managers, affected communities and stakeholders. 

This evaluation should include an assessment of whether the program is meeting its goals 

regarding improving ecosystem health and reducing the damaging effects of catastrophic 
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wildfires. We are proposing to add to §51.308(g) a requirement for the periodic progress report 

on a state’s regional haze program to include a summary of the most recent periodic assessment 

of any smoke management program that is part of the long term strategy. 

While the Regional Haze Rule thus does not require regional haze SIPs to include 

measures to limit emissions from prescribed fire, it is not our intention to in any way discourage 

federal, state, local or tribal agencies or private land owners from taking situation-appropriate 

steps to minimize emissions from prescribed fires on wildlands, or other types of lands. The EPA 

joins the FLMs in encouraging all land owners and managers to apply appropriate basic smoke 

management practices to reduce emissions from prescribed fires. The EPA understands that the 

FLMs apply these measures routinely and will be available to consult with other agencies and 

private parties interested in doing the same. We also encourage any state with an existing smoke 

management program or considering the adoption of a smoke management program to consider 

how its provisions may affect the ability of land owners and managers to apply prescribed fire 

where it is needed for wildland ecosystem health and to reduce the risk of catastrophic wildfires 

as discussed earlier in this section. 

Possible effect on the comparison of the RPG to the URP line. Prescribed fire on 

wildlands may contribute to impairment on some of the days that are among the 20 percent most 

impaired days. Therefore, the issue of whether prescribed fires might cause the projected RPG to 

be above the URP line is germane. 

Generally, as discussed earlier in this section, we do not expect the total acreage subject 

to prescribed fires on wildlands to decrease in the future because prescribed fire is needed for 

ecosystem health and to reduce the risk of catastrophic wildfires. Thus, the occurrence of 

prescribed fire generally will not be projected to decline towards zero by 2064, nor to decline 
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over any one implementation period at the proportional rate inherently assumed in the URP line. 

In fact, in many areas there may be reason to adopt policies that facilitate, and accordingly to 

forecast for purposes of setting the RPG, more use of prescribed fire and thus higher 

contributions to impairment on the 20 percent most impaired days. At this time, we do not know 

whether or where such a projected trend may affect whether the RPG for a Class I area will be 

above the URP line. However, we expect that if this is an issue, western Class I areas would be 

the more likely to be affected. 

If the projected RPG for a Class I area is above the URP line due only to the anticipated 

use of wildland prescribed fire needed for ecosystem health and safety, we do not believe that 

states should expend valuable analytical and decision making resources on additional analysis of 

measures necessary for reasonable progress if they have otherwise satisfied the terms of the 

Regional Haze Rule. Therefore, as in the case of impacts from sources in other countries as 

discussed in section IV.D, we are requesting comment on a proposed provision in 

§51.308(f)(1)(vi) that would allow states with Class I areas significantly impacted by emissions 

from wildland prescribed fires to make an adjustment to the URP with specific approval by the 

Administrator. The adjustment would consist of adding to the value of natural visibility 

conditions an estimate of wildland prescribed fire impacts, only for the purpose of calculating the 

URP and only for prescribed fires that were conducted with the objective to establish, restore 

and/or maintain sustainable and resilient wildland ecosystems, to reduce the risk of catastrophic 

wildfires and/or to preserve endangered or threatened species during which appropriate basic 

smoke management practices were applied. FLMs prepare multi-year land and/or resource 

management plans for the areas they manage that document the objective of prescribed fire for a 

land area. We would also consider a fire management plan for state, tribal or private lands that 
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has been reviewed and certified by the appropriate fire and/or resource management 

professionals and agreed to and followed by the land owner/manager to be sufficient to meet this 

restriction on the scope of the adjustment to the URP.45 Other evidence of the objective of a 

prescribed fire would be considered on a case-by-case basis. We believe that this adjustment 

should be permitted only if such prescribed fire impacts have been estimated with methods and 

data approved by the Administrator as scientifically valid.46

We are also proposing changes to fire-related definitions in §51.301. One of the proposed 

changes is to remove the term “prescribed natural fire” for the definition of “fire” because we 

consider prescribed fires to be anthropogenic, although we recognize that some prescribed fires 

are merely substitutes for natural wildfire that would otherwise occur at some point in time. In 

addition, we are adding definitions for wildland, wildfire and prescribed fire. The proposed 

definitions are consistent with the definitions we recently proposed for inclusion in the 

Exceptional Events Rule. 

EF. Clarification of and Changes to the Required Content of Progress Reports 

The EPA believes that additional amendments to §51.308(g) are appropriate at this time 

in order to clarify the substance of the regional haze progress reports. In its current form, there is

ambiguity in this section with respect to the period to be used for calculating current visibility 

conditions, as well as ambiguity with respect to whether forward-looking, quantitative modeling 

 

45 Examples of these plans include federal land or resource management plans, State Forest 

Action Plans, fire management plans, prescribed fire on wildland management plans or 

landscape management plans.

46 The invitation, in the context of international impacts, for comment on alternative adjustment 

approaches also applies to this proposal regarding an adjustment to account for prescribed fire 

impacts. Our recommendation for consultation with other states and FLMs in the same context 

also applies to prescribed fire impacts. 
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is required in the progress reports to assess whether reasonable progress goals will be met. The 

EPA wishes to clarify both of these and other issues, and so proposes to amend §51.308(g) in the 

following ways. The EPA seeks comment on these proposed amendments as well as alternative 

approaches. 

Section 51.308(g)(3)(ii) is proposed to be amended by adding a number of explanatory 

sentences to better indicate what “current visibility conditions” are and how to calculate them. 

Under the current version of the rule, it is not clear what “current visibility conditions” are, in 

part because the term is not defined in §51.301. Although §51.308(g)(3) makes reference to 5-

year averages of annual values for most impaired and least impaired days, and §51.308(g)(3)(i) 

requires states to assess current visibility conditions for the most impaired and least impaired 

days, there is no clear indication as to which 5-year average the state should and can practicably 

use in a progress report for the current visibility conditions calculation. For example, the “current 

conditions” terminology does not explicitly allow for the time delay needed for the IMPROVE 

network manager to get quality assured data into its database so they are accessible to the states 

preparing progress reports. Practicality requires that “current conditions” should mean 

“conditions for the most recent period of available data.”47 There is also an issue of whether this 

availability is to be determined based on the start of work on the progress report, the due date for 

the progress report, or the actual submission date of the progress report. The proposed text makes 

clear that the period for calculating current visibility conditions is the most recent rolling 5-year 

 

47 In our guidance on the preparation of progress reports, the EPA has indicated that for “current 

visibility conditions,” the reports should include the 5-year average that includes the most recent 

quality assured public data available at the time the state submits its 5-year progress report for 

public review. See section II.C of General Principles for the 5-Year Regional Haze Progress 

Reports for the Initial Regional Haze State Implementation Plans, April 2013. 
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period for which IMPROVE data are available as of a date 6 months preceding the required date 

of the progress report. Because we are also proposing that progress reports no longer be 

submitted as SIP revisions, meaning that there would be a much simpler and expeditious state 

administrative process to submit a progress report once technical work on it is completed, we 

believe that this 6-month period would be sufficient for states to incorporate the most recent 

available data into their progress reports.48 The EPA invites comment on other specific 

timeframes as the amount of time necessary for states to incorporate the most recent available 

data into their progress reports, including 3 months, 9 months and 12 months.

Section 51.308(g)(3)(iii), as currently written, requires a progress report to contain the 

value of the change in visibility impairment for the most and least impaired days over the past 5 

years. This text fails to make clear what the “past 5 years” are for assessing the change in 

visibility impairment. Because of data reporting delays, the period covered by available 

monitoring data will not line up with the periods defined by the submission dates for progress 

reports. Moreover, it is important to ensure that each year of visibility information is included 

either in a periodic comprehensive SIP revision or the progress report that follows it. Therefore, 

the “past 5 years” text is proposed to be deleted and replaced with text indicating the change in 

visibility impairment is to be assessed over the period since the period addressed in the most 

recent periodic comprehensive SIP revision. 

The same change to existing “past 5 years” text is proposed to be made to the first 

sentence of §51.308(g)(4) for the purposes of reporting changes in emissions of pollutants 

 

48 Note that we are not proposing this specification of 6 months for the progress report aspects of 

a periodic comprehensive SIP revision (see section IV.C), in light of the longer time needed for 

administrative steps between completion of technical work and submission to the EPA. 
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contributing to visibility impairment, for similar reasons. Like monitoring trend summaries, 

available emissions trend summaries will not line up with the periods defined by the submission 

dates of progress reports. Therefore, the proposed language removes the “past 5 years” text and 

replaces it with text indicating the change in emissions of pollutants contributing to visibility 

impairment is to be assessed over the period since the period addressed in the most recent 

periodic comprehensive SIP revision. 

The final sentence of §51.308(g)(4) is proposed to be modified to revise and clarify the 

obligation of states regarding emissions inventories. The current rule text directs the analysis be 

based on the “most recent updated emissions inventory,” with emissions estimates “projected 

forward as necessary and appropriate to account for emissions changes during the applicable 5-

year period.” States are otherwise required by 40 CFR part 51, subpart A (Air Emissions 

Reporting Requirements) to prepare complete emission inventories only for every third calendar 

year (2011, 2014, etc.) and to submit these inventories to the EPA’s National Emissions 

Inventory (NEI). (After aggregating and quality assuring these submissions, the EPA then 

publicly provides summaries of the inventories that have been submitted.) The current text of 

§51.308(g)(4) seemingly requires a state to “project” the most recent of these inventories to the 

end of the “applicable 5-year period” whenever that end is not the year of a triennial inventory 

required by subpart A. Emissions projection is not a simple or low-resource task even if limited 

to a projection date that is in the recent past, as would be the case here. We do not think the 

informational value of such projections is in balance with the effort and time that would be 

required. At the same time, we believe that progress reports should present for each significant 

source sector the most recently available information, which may be newer for some sectors than 

for others. For most sectors, this will be the information for the triennial year of the most recent 
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NEI submission. However, the EPA operates a data system that provides information on 

emissions from electric generating units (EGUs), which account for a significant percentage of 

visibility impairing pollution in many states, with only a few months lag time. This information 

comes from reports submitted by the EGU operators based on continuous emissions monitoring 

systems. Therefore, we are proposing text changes that explain clearly the most recent year 

through which the emissions analysis must be extended, by sector. States would be required to 

include in their progress reports emissions with respect to all sources and activities up to the 

triennial year for which information has already been submitted to the NEI. With regard to 

EGUs, states would need to include data up to the most recent year for which the EPA has 

provided a state-level summary of such EGU-reported data. Finally, the last sentence of the 

proposed text for this section makes clear that if emission estimation methods have changed from 

one reporting year to the next, states need not backcast, i.e., use the newest methods to repeat the 

estimation of emissions in earlier years, in order to create a consistent trend line over the whole 

period. The EPA has never expected states to backcast in this context, but some states have 

expressed concern that other parties may interpret the current Regional Haze Rule as requiring 

such backcasting. This final change would remove any uncertainty about the sufficiency of a 

state’s progress report. 

Section 51.308(g)(5) involves assessments of any significant changes in anthropogenic 

emissions that have occurred, and is proposed to be changed in a similar fashion to other 

sections, deleting the reference to the “past 5 years” and instead directing that the period to be 

assessed involves that since the last periodic comprehensive SIP revision. Text is also proposed 

to be added that would require states to report whether these changes were anticipated in the 

most recent SIP. Having this explanation within the progress report should not be a significant 
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burden on the state and will assist the FLMs, the public and the EPA in understanding the 

significance of any change in emissions for the adequacy of the SIP to achieve established 

visibility improvement goals. The EPA was encouraged in pre-proposal consultations with FLMs 

to add this requirement.

Proposed changes toThe existing §51.308(g)(6) is proposed to be renumbered as 

§51.308(g)(7). Proposed changes to its provisions regarding assessment of progress toward 

meeting reasonable progress goals would clarify that the reasonable progress goals to be assessed 

are those established for the period covered by the most recent periodic comprehensive SIP 

revision. This does not change the intended meaning of this section, and only clarifies that in a 

progress report, a state is not required to look forward to visibility conditions beyond the end of 

the current implementation period.

The new §51.308(g)(6) is proposed to include a provision requiring a state whose longterm strategy includes a smoke management program for prescribed fires on wildland to include 

a summary of the most recent periodic assessment of the smoke management program.

A final proposed change to §51.308(g) is to remove the provisions of the existing 

§51.308(g)(7) entirely, relieving the state of the need to review its visibility monitoring strategy 

within the context of the progress report. This change was requested by many states during our 

pre-proposal consultations, and is appropriate in our view. Because all states currently rely on 

their participation in the IMPROVE monitoring program and expect to continue to do so, 

continuing the requirement for every state to submit a distinct monitoring strategy element in 

each progress report would consume state and EPA resources with little or no practical value for 

visibility protection. As needed, the EPA will work with involved states and the IMPROVE 

Steering Committee to address any needed changes in the visibility monitoring program. 
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It should be noted that minor changes are proposed to §51.308(h) regarding actions the 

state is required to take based on the progress report. These changes merely remove the 

implication that all progress reports are to be submitted at 5-year intervals, and improve public 

understanding of the declaration that a state must make when it determines that no SIP revisions 

are required by removing the word “negative.” Minor changes are also proposed to §51.308(i) in 

order to create a stand-alone requirement that states must consult with FLMs regarding progress 

reports. This stand-alone requirement is needed if progress reports are not SIP revisions, because 

at present the FLM consultation requirements are applicable only to SIP revisions. 

GF. Changes to Reasonably Attributable Visibility Impairment Provisions 

The EPA is proposing extensive changes to 40 CFR 51.300 through 51.308 in regard to 

reasonably attributable visibility impairment. As discussed in section III of this document, the 

reasonably attributable visibility impairment provisions were originally promulgated in 1980, 

when technology for evaluating visibility impairment and its causes was in its infancy and visual 

observation of “plume blight” was the main method of determining whether a source was 

affecting a mandatory Class I area. Since that time, there have been many advances in ambient 

monitoring, emissions quantification, emission control technology and meteorological and air 

quality modeling. These advances have been built into the regional haze program, such that state 

compliance with the Regional Haze Rule’s requirements will largely ensure that progress is 

made towards the goal of natural visibility conditions. Therefore, it is likely that some aspects of 

the reasonably attributable visibility impairment provisions of the visibility regulations have less 

potential benefit than they did when they originally took effect over 3 decades ago. In addition, 

the reasonably attributable visibility impairment provisions have received few amendments over 
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the years, including during amendments made by the Regional Haze Rule in 1999 where the 

changes to integrate the reasonably attributable visibility impairment assessment and mitigation 

provisions with the new regional haze program requirements were limited to putting the two 

separately designed programs on the same recurring schedule. This has left a substantial amount 

of confusing and outdated language within the current visibility regulations including seemingly 

overlapping and redundant requirements, particularly between §§51.302 and 51.306. Also, as 

noted in section III.A, in actual practice the portion of the reasonably attributable visibility 

impairment provisions mandating periodic assessment of reasonably attributable visibility 

impairment by states (or by the EPA in the case of states that do not have an approved 

reasonably attributable visibility impairment SIP) has not resulted in any additional emission 

control requirements being placed on emission sources. While there have historically been very 

few certifications of existing reasonably attributable visibility impairment by an FLM, in several 

situations a certification by an FLM has ultimately resulted in new controls or changes in source 

operation. 

The EPA therefore believes it is time to bring clarity to the reasonably attributable 

visibility impairment provisions of the rule and enhance the potential for environmental 

protection. In brief, The our proposed changes would (1) eliminate recurring requirements on 

states that we believe have no significant benefit for visibility protection;,49 (2) clarify and 

strengthen the existing provisions under which states must address reasonably attributable 

visibility impairment when an FLM certifies that reasonably attributable visibilitysuch

 

49 These changes, when finalized, would mean that those states with SIPs that commit them to 

periodically assess whether reasonably attributable visibility impairment is occurring at their 

Class I areas could remove that commitment from their SIPs. 
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impairment is occurring in a particular Class I area due to a single source or a small number of 

sources;, (3) remove existing FIP provisions which that require the EPA to periodically assess 

whether reasonably attributable visibility impairment is occurring and to respond to FLM 

certifications of reasonably attributable visibility impairment,; and (4) edit various portions of 

§§51.300-308 to make them clearer and more compatible with each other. The substantive and 

clarifying changes are described in the following discussion here in order of section number. The 

EPA seeks comment on each of the following proposed changes, as well as any suggestions for 

alternative approaches to modernizing the reasonably attributable visibility impairment 

provisions. 

The EPA is proposingProposed changes toto amend §51.300, Purpose and applicability, 

to would include a proposed change to section (b) to delete the reference to reasonably 

attributable visibility impairment only being applicable to the 36 states and territories with 

mandatory Class I areas. Instead, under the proposed amendments, theexpand the amended 

reasonably attributable visibility impairment requirements would apply to all states and 

territories, with the exceptions of Guam, Puerto Rico, American Samoa, and the Northern 

Mariana Islands., since tTheose territories have no mandatory Class I areas and are sufficiently 

far from other Class I areas to have no anticipated impact on visibility in these such areas. Under 

our proposal, Tthe geographical coverage of the reasonably attributable visibility impairment 

provisions and the regional haze provisions would then be the same. The EPA believes these 

changes are appropriate and would strengthen the visibility program and are appropriate , given 

in light of the evolved understanding that pollutants emitted from one or a small number of 

sources can affect Class I areas many miles away. In other words,, so that emissions occurring in 

states without Class I areas can affect downwind states with Class I areas. The proposed changes, 
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therefore,This proposed change would provide these areas with additional protection from 

reasonably attributable visibility impairment. 

The EPA is proposingProposed changes toto amend §51.301, Definitions, would involve 

changes to change the definition of reasonably attributable. The current definition of reasonably 

attributable is, “attributable by visual observation or any other technique the State deems 

appropriate.,” is We are proposinged to be modify this definition to read changed to “attributable 

by visual observation or any other appropriate technique.” This change would remove the current 

implication that only the a state can determine what techniques is are appropriate, even if the 

though the FLMs is are charged with certifying reasonably attributable visibility impairment. 

The proposed change would make it clear that a state does not have complete discretion to 

determine what techniques are appropriate for attributing visibility impairment to specific 

sources. It is appropriate that the EPA be able to review the technique(s) that an FLM has relied 

upon to determine that reasonably attributable visibility impairment is occurring, in light of the 

views and supporting information provided by both the FLM and the state. While these views 

and supporting information, regardless of whether provided by the FLM or by the state, will not 

be presumptive in EPA’s ultimate determination as to whether any attribution technique used is 

appropriate, the universe of potentially appropriate attribution techniques is not limited to only 

those techniques that may have been utilized during past reasonably attributable visibility 

impairment certifications or that have been previously recommended or discussed via EPA 

guidance or actions. Rather, the aforementioned advances in ambient monitoring, emissions 

quantification, emission control technology and meteorological and air quality modeling that 

have occurred in the decades since 1980 make clear that modeling is one possible technique for 

determining that reasonably attributable visibility impairment is occurring.
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 Due to the confusing, and in large part outdated, content of §51.302, the EPA is 

proposing to delete the entire text of this section is proposed to be deleted andand replace it with

completely new language inserted. The new text would clearly describes a state’s responsibilities 

upon receiving a FLM certification of reasonably attributable visibility impairment. The 

proposed changes also include a change to the current section title, “Implementation control 

strategies for reasonably attributable visibility impairment,” such that it reads “Reasonably 

attributable visibility impairment.” 

 The proposed §51.302(a) involves FLM certification of reasonably attributable visibility 

impairment and reads much like the existing §51.302(c), with the added language that FLMs 

would identify in the certification which single source or small number of sources is responsible 

for the reasonably attributable visibility impairment being certified.50 Further, the original 

reasonably attributable visibility impairment formulation did not anticipate a situation where one 

or a small number of sources in one state could create impairment of visibility in other state(s). 

Therefore, proposed language is included to explain that the FLMs would provide the 

certification to the state in which the source or small number of sources is located, which may 

not necessarily be the state where the visibility impairment occurs. The proposed language also 

addresses the possible situation that a “small number of sources” may be partially in one state 

and partially in another, such that a certification might be addressed to multiple states. 

 

50 The existing rule text at §51.302(c)(1) does not explicitly require the FLM to identify a 

particular source or small number of sources as responsible for the reasonably attributable 

impairment, but the EPA and the FLMs understand that such identification should be part of a 

certification. See 45 FR 80086, “The Federal Land Manager may provide the State with a list of 

sources suspected of causing or contributing to visibility impairment in the mandatory Class I 

Federal area.” Under the proposed new language of §51.302(b), if the FLM does not identify the 

source or small number of sources causing the impairment, the certification would not create any 

obligation on the state to respond with a SIP revision. 
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 The proposed §51.302(b) describes the required state action in response to any FLM 

reasonably attributable visibility impairment certification, i.e., regardless of the type of source, 

namely that a state shall revise its regional haze implementation plan to include a determination, 

based on the four reasonable progress factors set forth in §51.308(d)(1)(i)(A), of any controls 

necessary on the certified source(s) to make reasonable progress toward natural visibility 

conditions in the affected Class I area. This preserves the current state obligation with much the 

same wording as in the current section, including the fact that a certification by an FLM would 

not create a definite state obligation to adopt a new control requirement, but rather only to submit 

a SIP revision that provides for any controls necessary for reasonable progress. In some cases, 

this SIP revision could be combined with an already required SIP revision. The EPA would 

review the responding SIP, and would be available to consult with the state and the certifying 

FLM as the state prepares its responding SIP. It iswould be the EPA, not the certifying FLM, that 

willwould determine whether the responding SIP is adequate and the response reasonable. The 

proposed section further maintains the current requirement that the state include emissions 

limitations and schedules for compliance, and adds the requirement that SIPs include monitoring, 

recordkeeping and reporting requirements in order to enforce those emissions limitations.

 The proposed §51.302(c) addresses those situations where an FLM certifies as a 

reasonably attributable visibility impairment source a BART-eligible source where there is at 

that time no SIP or FIP in place setting BART emission limits for that source or addressing 

BART requirements via a better-than-BART alternative program.51 In such an instance, the 

 

51 Although most of the BART requirements have been addressed in most states, there remain a 

handful of states with BART obligations. In addition, there is litigation over the BART element 

in some approved SIPs and promulgated FIPs. We expect that this situation may exist in one or 

more states at some time after the effective date of the final rule. 
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proposed rule requires the state to revise its regional haze SIP to meet the requirements of 

§51.308(e), BART requirements for regional haze visibility impairment, and notes that this 

requirement exists in addition to the requirements of §51.302(b) regarding imposition of controls 

for reasonable progress. The new version of §51.302(c) clarifies two aspects of the current rule 

to match the EPA’s past and current interpretations. First, a reasonably attributable visibility 

impairment certification for a BART-eligible source prior to the EPA’s approval of a state’s 

BART SIP for that source does not impose any substantive obligation on a state that is over and 

above the BART obligation imposed by §51.308. However, the state’s response to the reasonably 

attributable visibility impairment certification of a BART-eligible source must take into account 

current information. This may require a state to update an analysis prepared earlier in support of 

a BART SIP that has not been approved. Second, a reasonably attributable visibility impairment 

certification of a BART-eligible source after the state’s BART SIP for that source has been 

approved by the EPA does not trigger a requirement for a new BART determination based on the 

five statutory factors for BART. Rather, the state’s obligation with respect to that source is the 

same as for a non-BART eligible source, as stated in the paragraph immediately earlier. This is 

true regardless of how the state’s SIP has addressed the BART requirement for the source, 

whether through source-specific emission limits, an alternative better-than-BART analysis, or the 

special provisions of §51.309, which may have not resulted in any new emission limit for the 

source. 

 Regarding the time schedule for state response to an FLM certification of reasonably 

attributable visibility impairment, we are considering a number of possible approaches for the 

final rule, but proposed rule text is provided only for the most complicated of these approaches. 

This approach will be explained first. 
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 tThe proposed rule text at §51.302(d) provides for different deadlines for the state 

response to the certification depending on when in the cycle of periodic comprehensive SIP 

revisions the reasonably attributable visibility impairment certification is made. Table 21

provides specific examples of how application of the proposed approach in the proposed rule text 

would determine due dates for the state response to a certification. 

• If the certification is made more than 2 years prior to the due date for any periodic 

comprehensive regional haze SIP revision required under §51.308(f) (but, with respect to 

the SIP due for the just-prior period, not so early as to be within the 6-month window 

described next), then a state must respond to the certification in that upcoming SIP 

revision. Failure to respond adequately would prevent full approval of that SIP revision. 

If the certification is made more than 2 years before the SIP due date, the state would 

have more than 2 years to respond, except as provided in the next bullet.52

• If the certification is made less than 2 years prior to the due date for any periodic 

comprehensive SIP revision (but no more than 6 months subsequent to the submission 

date of that periodic comprehensive regional haze SIP revision or a SIP revision that 

amends a previous submission in a way that affects the emission limits applicable to the 

reasonably attributable visibility impairment-certified source 53), then the state must 

submit a revision to its regional haze SIP within 2 years from the date of certification. 

 

52 For a certification made between the 2021 and 2028 SIP due dates, the state might have up to 

6.5 years to respond, assuming the next bullet does not apply. For a certification made between 

the 2028 and 2038 due dates, the state might have up to 9.5 years to respond. 

53 If a certification is made not too long after a SIP due date, this parenthetical provision would 

operate to require the SIP revision needed to respond to the reasonably attributable visibility 

impairment certification to be due sooner than the 6.5 or 9.5 year extreme noted in the previous 

footnote. 
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The EPA believes that in this second timing situation, when the state’s analytical 

infrastructure has been recently used to prepare a SIP revision and thus would not be in 

need of much if any refreshment, it is appropriate to require a responding SIP revision 

without waiting longer than 2 years for the next periodic comprehensive SIP revision. In 

this timing situation, the EPA would act on the state’s standard regional haze SIP without 

regard to the not-yet-due obligation for a reasonably attributable visibility impairmentresponse SIP revision. 

Table 12: Example FLM Reasonably Attributable Visibility Impairment Certification 

Dates and Corresponding Due Dates for State Response. All assume submission of a SIP 

revision by July 31, 2021, unless otherwise noted. 

Date of FLM certification Proposed due date for state response 

July 30, 2019 July 31, 2021 

August 1, 2019 August 1, 2021 

January 30, 2022 January 30, 2024 

February 1, 2022 July 31, 2028 

April 1, 2022, after late submission of a SIP 

on March 1, 2022 

April 1, 2024 

August 31, 2022, after revised SIP 

submission on July 31, 2021, affecting the 

source identified in the reasonably 

attributable visibility impairment 

certification 

August 31, 2024 

The EPA considers theseThese timing provisions the bestcan be viewed as a compromise 

between possibly requiring more than one major planning activity during each (approximately) 

10-year SIP cycle and obtaining the benefit of additional emission controls via a response to an 

FLM certification of reasonably attributable visibility impairment within a reasonable time 

period. These proposed provisions in the proposed rule text also reflect the fact that an FLM 

may, in rare cases, wish to certify a reasonably attributable visibility impairment source after 

reviewing (and having disagreements with) a SIP that a state has recently submitted to the EPA. 
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The EPA invites comment on this timing approach shown in Table 2 and the proposed rule 

text, but also onas well as other, simpler approaches that would strike a compromise that leans 

more towards obtaining additional visibility improvements sooner following a FLM certification 

of reasonably attributable impairment at a Class I area. that may provide an even better 

compromise between the often competing analysis and planning obligations and workloads of 

states, the EPA and FLMs, and the need to respond in a timely way to a reasonably attributable 

visibility impairment certification by an FLM. In particular, the EPA invites comment on (1) 

retaining the existing requirement for a state to respond to a reasonably attributable visibility 

impairment certification with a SIP revision within 3 years regardless of when the certification is 

made in the cycle of periodic comprehensive SIP revisions and (2) requiring the state’s 

responsive SIP revision to be submitted on the due date of the next progress report (but not as 

part of the progress report, if the final rule does not require progress reports themselves to be 

submitted as SIP revisions) or the next periodic comprehensive SIP revision whichever is earlier 

provided the earlier date is at least 2 years after the RAVI certification. The final rule may 

incorporate any one of these three proposals, or may combine features of these proposals.

It is important to note that as proposedregardless how the final rule sets the deadline for 

the state’s responsive SIP revision, if the reasonable progress goals in the periodic 

comprehensive regional haze SIP for a state with a Class I area (and thus required to have 

reasonable progress goals in its SIP for that area) have beenis approved prior to the approval of 

its own or a contributing state’s separate reasonably attributable visibility impairment-response 

SIP, the state would not be required to revisit and revise its reasonable progress goals to take into 

account any additional emission reductions from the certified source until the next due date for a 

periodic comprehensive SIP revision. 
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 Proposed changes to §51.303, Exemptions from control, are minor edits to paragraph (a) 

designed to correctly refer to the new §51.302(c) as well as to the BART provisions in 

§51.308(e). These proposed changes do not alter which existing facilities may apply to the 

Administrator for an exemption from BART. Rather, the proposed changes simply make the 

language more clear and direct the reader to the appropriate sections for reference information. 

 Proposed changes to §51.304, Identification of integral vistas, are more extensive. An 

integral vista is defined in §51.301 as a view perceived from within the Class I area of a specific 

landmark or panorama located outside the boundary of the Class I area. The current version of 

§51.304 was written at a time when FLMs were still in the process of identifying integral vistas. 

We are proposing to remove antiquated language in §51.304 in light of the fact that FLMs were 

required to identify any such integral vistas on or before December 31, 1985. The proposed 

language would explain this fact as well as list those few integral vistas that were properly 

identified during the applicable time period. States would continue to be subject to the 

requirement that these integral vistas be listed in their SIPs. The EPA notes that the current 

version of 40 CFR part 51, subpart P is not perfectly clear on how the existence of an identified 

integral vista affects obligations on states and sources, but we are not proposing any clarification 

as part of this rulemaking.54 We invite comment on whether all references to integral vistas 

should be removed from subpart P, and we may do so in the final rule. 

 

54 Section 51.301 states that “visibility in any mandatory Class I Federal area includes any

integral vista associated with that area” but also that “adverse impact on visibility” does not 

include effects on integral vistas. Section 307(b) requires that SIPs provide for the review of any 

new major stationary source or major modification that may have an impact on any integral vista 

of a mandatory Class I Federal area. Other references to “integral vista” are merely definitional 

or relate to the procedure for identifying integral vistas. 
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 Proposed changes to §51.305, Monitoring for reasonably attributable visibility 

impairment, involve adding language stating that the requirement for a state to include in a 

periodic comprehensive SIP revision a monitoring strategy specifically for evaluating reasonably 

attributable visibility impairment in Class I area(s) only applies in situations where the 

Administrator, Regional Administrator or FLM has advised the state of a need for it. In concept, 

special monitoring for reasonably attributable visibility impairment purposes might be 

appropriate for a Class I area without an IMPROVE monitoring station or when the impairment 

is from a relatively narrow plume such that the existing IMPROVE monitoring site is not 

affected. The nature of the special monitoring might be situation-specific, and might be the same 

as or different than the IMPROVE monitoring protocols. These proposed changes would reduce 

the paperwork that states are required to submit to the EPA on a recurring schedule, since under 

the proposed language a state containing one or more Class I areas and participating in the 

IMPROVE monitoring program would be relieved of the need to include information in its SIP 

regarding monitoring to specifically assess reasonably attributable visibility impairment absent 

being advised to do so. A strategy for monitoring for regional haze visibility impairment under 

§51.308(d)(4) is still required and any monitoring for reasonably attributable visibility 

impairment under §51.305 would be in addition to that requirement. 

Section 51.306, on long-term strategy requirements for reasonably attributable visibility 

impairment, is proposed to be completely removed and reserved. Like the current version of 

§51.302, the language of this section is out-dated. In this case, the EPA believes it makes sense 

to delete the entire text of this section and instead refer to long-term strategy requirements for 

reasonably attributable visibility impairment within the text of §51.308, specifically in 

§51.308(f)(2). In this way, long-term strategy requirements for reasonably attributable visibility 
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impairment would be retained in clearer form, and the visibility program would be more 

understandable to states and the public by listing the long-term strategy requirements for both 

regional haze and reasonably attributable visibility impairment in one place. Such a change 

would also reduce the planning burden on states by making clear in §51.308(f)(2) that a longterm strategy for reasonably attributable visibility impairment is not required without an FLM 

having made a reasonably attributable visibility impairment certification under §51.302(a). 

 Several proposed changes in §51.308 were discussed in sections IV.A, B, C, D, E and F 

of this document. We are also proposing changes in §51.308 related to reasonably attributable 

visibility impairment. The proposed addition of §51.308(c) (currently a reserved section) 

explains the relationship between regional haze and reasonably attributable visibility impairment 

and the state requirements for each, including that a state would not be required to address 

reasonably attributable visibility impairment unless triggered to do so by an FLM certification 

under §51.302(a), and that a state would not be required to re-address its monitoring strategy for 

reasonably attributable visibility impairment unless advised to perform monitoring as described 

in the proposed §51.305. 

 The EPA is also proposing changes to the language of §51.308(f)(2) to describe when 

reasonably attributable visibility impairment must be addressed in the long-term strategy 

required for regional haze. Finally, proposed changes to §51.308(f)(6) regarding the monitoring 

strategy requirements for SIPs would remove references to §51.305 that exist in the 

corresponding subsection in §51.308(d), namely, subsection (4) (again, regarding monitoring for 

reasonably attributable visibility impairment). 

 Proposed changes to §51.308(e), BART, relate to a state’s option to enact an emissions 

trading program or other alternative measure in lieu of source-specific BART. Under the 
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proposed approach, if a source is already covered for BART by an approved emissions trading 

program or other alternative measure (or the program codified in §51.309), certification of that 

source by an FLM would not trigger a new BART determination. However, certification would 

still trigger the requirement for a reasonable progress analysis. Proposed changes to 

§51.308(e)(4) are similar in nature and motivated by the same concerns. 

 Consistent with our proposal to remove the requirement for states to periodically assess 

reasonably attributable visibility impairment, we are also proposing to amend many sections of 

40 CFR part 52, to remove provisions that establish FIPs that require the EPA to periodically 

assess whether reasonably attributable visibility impairment exists at Class I areas in certain 

states and to address it if it does, and to respond to any reasonably attributable visibility 

impairment certification that may be directed to a state that does not have an approved 

reasonably attributable visibility impairment SIP. These changes include the removal of §§52.26 

and 52.29, which now contain the statement of the EPA’s obligations, and specific provisions for 

30 states to establish that §§52.26 and 52.29 are applicable to those states. 

GH. Consistency Revisions Related to Permitting of New and Modified Major Sources 

Proposed changes to §51.307, New Source Review, involve a few proposed changes to 

maintain consistency with other sections of the Regional Haze Rule and with the CAA. The first 

change involves §51.307(b)(1) concerning integral vistas, for which we are proposing deletion of 

obsolete language regarding the now-expired identification period for integral vistas. Instead, the 

newly proposed addition of a listing of integral vistas in §51.304(b) will be referenced. In section 

§51.307(b)(2), the deletion of a reference to specific sections of the CAA is proposed in order to 

remove unnecessary language, as the EPA believes a reference simply to section “107(d)(1)” is 

sufficient. 
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HI. Changes to FLM Consultation Requirements 

The EPA believes that state consultation with FLMs is a critical part of the creation of 

quality SIPs. As mentioned earlier, the EPA is proposing to extend the FLM consultation 

requirements of §51.308(i)(2) to progress reports that are not SIP revisions. In addition, the EPA 

believes further edits to §51.308(i)(2) are necessary because the current requirement for 

consultation at least 60 days prior to a public hearing may not occur sufficiently early in the 

state’s planning process to meaningfully inform the state’s development of the long-term 

strategy. This proposed rule change would add a requirement that such consultation occur early 

enough to allow the state time for full consideration of FLM input, but no fewer than 60 days 

prior to a public hearing or other public comment opportunity. A consultation opportunity that 

takes place no less than 120 days prior to a public hearing or other public comment opportunity 

would be deemed to have been “early enough.” 

IJ. Extension of Next Regional Haze SIP Deadline from 2018 to 2021 

The EPA is proposing to amend the requirements in 40 CFR§ 51.308(f) regarding state 

submission of periodic comprehensive SIP revisions beginning no later than July 31, 2018, and 

every 10 years thereafter. We are proposing to amend this section to move the compliance 

deadline for the submission of the next instead allow states until July 31, 2021, to submit the 

periodic comprehensive SIP revisions originally due by from July 31, 2018, to July 31, 2021. 

Under this proposal, Astates would state would haveretain the option of submitting its their SIP 

revisions before July 31, 2021. Regardless of the date on which a state chooses to submit its 

periodic comprehensive SIP revision, the EPA would evaluate that SIP using the same criteria, 

with the SIP being evaluated under the same criteria as a SIP submitted on the due date. The 

EPA is proposing to Theleave the end date for of the second implementation period at 2028 for 
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these SIP revisions would remain 2028, regardless of when the SIP revisions is are submitted. 

We are proposinge this change as a one-time schedule adjustment. Beginning with the next 

pPeriodic comprehensive SIP revisions for the third planning will be due date ofon July 31, 

2028, the 10-year cycle of submission deadlines would resume, with future periodic 

comprehensive SIP revisions due every 10 years followingthereafter. 

We are proposing Thethis extension of the due date to 2021 for states to submit the 

periodic comprehensive SIP revisions now due in 2018 wouldfor periodic comprehensive SIP 

revisions to allow states to coordinate regional haze planning with other regulatory programs, 

including but not limited to the Mercury and Air Toxics Standards,55 the 2010 1-hour SO2

NAAQS,,

56 and the 2012 annual PM2.5 NAAQS.,57 and the Clean Power Plan.58 With this onetime extension, and the Clean Power Plan.59 sStates would be able to gather more information on 

the effects of these programs and develop periodic comprehensive SIP revisions (for the second 

implementation period) that are more integrated with state planning for these other programs, an 

advantage that was widely confirmed in our discussions with states. A required element of tThe 

Regional Haze Rule is thatrequires states to address the impacts of other regulatory programs 

when developing their regional haze plansSIPs. The EPA believes that as tAhe number of other 

regulatory programs will be taking effect in this the coming yearstimeframe is unusually high, 

this which presents an excellent opportunity for states to coordinateion of their strategies to 

 

55 77 FR 9304, February 16, 2012. 

56 75 FR 35520, June 22, 2010. 

57 78 FR 3086, January 15, 2013. 

58 80 FR 64,662, October 23, 2015. The compliance deadlines in the Clean Power Plan have been 

stayed by the Supreme Court. Order in Pending Case, West Virginia v. EPA, No. 15A773 (Feb. 

9, 2016).

59 80 FR 64662, October 23, 2015. 
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address significant sources of emissions. The EPA expects this cross-program coordination to 

lead to better overall policies and therefore enhanced environmental protection. 

JK. Changes to Scheduling of Regional Haze Progress Reports 

The EPA is proposing to amend the requirements in 40 CFR 51.308(g) and (h) regarding 

the timing of submission of reports evaluating progress towards the natural visibility goal. Under 

the current rule, regional haze progress reports are required to be submitted 5 years after 

submission of periodic comprehensive SIP revisions. Because states submitted these first SIP 

revisions on dates spread across about a 3-year period, many of the due dates for progress reports 

currently do not fall mid-way between the due dates for periodic comprehensive SIP revisions, as 

the EPA initially envisioned that they would. Looking forward, the current Regional Haze Rule 

would in many cases require a progress report shortly before or shortly after a periodic 

comprehensive SIP revision, at which time it could not be expected to have much utility as a 

mid-course review of environmental progress or much incremental informational value for the 

public compared to the data contained in that SIP revision. 

Complementing the proposed amendments to 40 CFR 51.308(f) regarding the deadlines 

for submittal of periodic comprehensive revisions, we propose to amend 40 CFR 51.308 (g) and 

(h) such that second and subsequent progress reports would be due by January 31, 2025, July 31, 

2033, and every 10 years thereafter, placing one progress report mid-way between the due dates 

for periodic comprehensive SIP revisions. The EPA believes that this timing provides a good 

balance between allowing the implementation of the most recent SIP revision to have proceeded 

far enough since its adoption for a review to be possible and worthwhile and having enough time 

remaining before the next comprehensive SIP revision for state action to make changes in its 

rules or implementation efforts, if necessary, separately from the actions in that next SIP. 
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Regarding the concept of a progress report also being useful at or near the time of 

submission of a periodic comprehensive SIP revision, as the EPA envisioned in the 1999 

Regional Haze Rule, we note that although they are expressed with somewhat different 

terminology, in practical terms a progress report would provide little additional information 

beyond that required to be addressed in a periodic comprehensive SIP revision. The only 

significant additional information required in a progress report but not explicitly required in a 

periodic comprehensive SIP revision is the requirement to report on the trend in visibility over 

the whole period since the baseline period of 2000-2004. While the EPA believes that a state 

should be aware of, and share with the public, information on the trend in visibility over the 

whole period since the baseline period of 2000-2004, we believe it would be inefficient to 

require the preparation of a separate progress report for this purpose. Therefore, we are 

proposing to limit the requirement for separate progress reports to the one due mid-way between 

periodic comprehensive SIP revisions, and to add to the requirement for periodic comprehensive 

SIP revisions a requirement to include this trend information. The EPA believes this approach 

would substantially reduce administrative burdens and make progress reports of more 

informational use to the public, with no attendant reduction in environmental protection. The 

EPA solicits comment on this and any alternative approaches to progress report scheduling. 

KL. Changes to the Requirement that Regional Haze Progress Reports be SIP Revisions 

The EPA is proposing to amend 40 CFR 51.308(g) regarding the requirements for the 

form of progress reports. Under the current regulations, progress reports must take the form of 

SIP revisions that comply with the procedural requirements of 40 CFR 51.102, 40 CFR 51.103 

and Appendix V to Part 51 – Criteria for Determining the Completeness of Plan Submissions. 

The EPA included the requirements for progress reports in the Regional Haze Rule primarily 
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with an emphasis toward ensuring that the states remain on track during the 10 years between 

periodic comprehensive SIP revisions. By requiring progress reports to be in the form of SIP 

revisions, the 1999 Regional Haze Rule ensured an opportunity for public input on the progress 

reports, while specifically pointing out that the EPA “intends for progress reports to involve 

significantly less effort than a comprehensive SIP revision.” 64 FR 35747 (July 1, 1999). For all 

SIP revisions, however, the state must provide public notice and a public hearing if requested, 

and it must conform to certain administrative procedural requirements and provide various 

administrative material. Also, the submission must be made by an official who is authorized by 

state law to submit a SIP revision. As a required SIP revision, a finding by the EPA that a state 

has not submitted a complete progress report by the deadline would start a “clock” for the EPA 

to prepare, take public comment on, and issue a progress report like the state was required to 

submit. 

We are proposing that progress reports need not be in the form of SIP revisions, but that 

states must consult with FLMs and obtain public comment on their progress reports before 

submission to the EPA. We are also proposing that the SIP revision that would be due in 2021 

must include a commitment to prepare and submit these progress reports to the EPA according to 

the proposed revised schedule (see previous section). These progress reports would be

acknowledged and assessed by the EPA, but our review of these reports would not result in a 

formal approval or disapproval of them. 

The EPA is proposing these changes because it believes these reports are not the kind of 

state submissions for which the formality of a SIP revision, and the accompanying requirement 

for the EPA to have to prepare the report within 2 years of finding that a state has failed to do so, 

are warranted. It is important to note that as part of the EPA’s review of the report, we will 
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follow up with the state on any appropriate next steps. There are also additional remedies, such 

as undertaking a less formal assessment of the results of the implementation of the previously 

submitted SIP, that are available to the EPA in the event a state fails to properly submit a 

progress report. These changes have been widely supported by state air agencies in our preproposal consultations because they would allow more efficient use of state resources. This 

option would relieve states of the obligation to follow the procedural requirements of 40 CFR 

51.102 and 51.103. States have expressed concern that these procedural requirements are 

resource-intensive, and increase the burden on states by requiring formal procedures be followed 

when submitting progress reports. By avoiding the specific formal steps required for a SIP 

revision, including requirements imposed by state law that may involve time-consuming steps 

beyond those required by the EPA, this proposal may also reduce the time between the 

completion of the technical analysis in the progress report and when the final report becomes 

available to the EPA and the public. Thus, progress reports could contain fresher information on 

the environmental progress being made by a state. Removing the requirement that progress 

reports be submitted as SIP revisions is consistent with regulatory requirements for similar 

reports from states for progress reporting or planning purposes where control requirements are 

not imposed, such as annual reports required under the Clean Power Plan for states that choose a 

state measures plan,60 or annual monitoring plans required for planning and maintenance of state 

monitoring networks.61

The EPA wishes to make clear that after consideringinvites comments on whether, the 

EPA may or may not it should finalize this proposed change. Also, the EPA may elect to 

 

60 See 40 CFR 60.57805870(c). 

61 See 40 CFR 58.10(a)(1) and (a)(2). 
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makeinvites comment on changes to changing the progress report scheduling as described in the 

previous section without making any change to the requirement that progress reports take the 

form of SIP revisions, and vice versa. The EPA solicits comments on these alternative 

approaches.

It is important to note that under this option, states would still be required to include the 

required progress report elements listed in 40 CFR 51.308(g)(1) through (g)(6). Also, §51.308(h) 

would continue to require that at the same time the state is required to submit a progress report, it 

must also take one of four listed actions concerning whether the SIP is adequate to achieve 

established goals for visibility improvement. Where a state determines that its own SIP is or may 

be inadequate to ensure reasonable progress due to emissions from sources within the state, the 

state will continue to have an obligation to revise its SIP to address the plan’s deficiencies within 

1 year of its submission of such a determination. 

Upon receipt of such progress reports, the EPA would review the reports. In addition, the 

EPA intends to create a system of logging progress reports as they are received, and making 

them available to the public. In addition to putting the public on notice that a progress report was 

received by the EPA, this system would provide the public an opportunity to view the contents of 

the progress report. Although the EPA would not formally approve or disapprove a progress 

report, the EPA would still have discretion to assess the adequacy of the SIP, relying in part on 

the information in the progress report. Under the CAA, a discretionary determination that the SIP 

is inadequate would create a non-discretionary duty for the EPA to issue a SIP call requiring the 

state to correct the inadequacy. A failure by the state to submit a progress report could be 

determined by the EPA to constitute failure to implement the regional haze SIP, given that we 
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are proposing that every regional haze SIP include a commitment to submit the required progress 

reports (see next paragraph). 

We are proposing that the next periodic comprehensive SIP revisions (currently due in 

2018 but proposed to be due in 2021) would need to include a commitment for states to provide 

progress reports. The 1999 Regional Haze Rule does not require such a commitment because the 

current requirement for progress reports to be submitted in the form of SIP revisions makes such 

a commitment superfluous. The EPA solicits comment on this or alternative approaches to 

ensuring that states continue to provide progress reports.

LM. Changes to Requirements Related to the Grand Canyon Visibility Transport Commission 

 Section 51.309 has limited applicability going forward because its provisions apply only 

to 16 Class I areas covered by the Grand Canyon Visibility Transport Commission Report, and 

only to the first regional haze implementation period (i.e., through 2018). Nevertheless, certain 

conforming amendments at this time are appropriate to avoid confusion going forward. Section 

51.309(d)(4)(v) is proposed to be amended to correctly refer to the new §51.302(b) (in lieu of 

(e), which no longer exists in the proposed section §51.302) and to delete the reference to BART 

since it does not appear in §51.302(b). The title of §51.309(c)(10), Periodic implementation plan 

revisions, is proposed to be amended to include “and progress reports” at the end. This insertion 

would complement the proposed amendments that will no longer require progress reports be 

considered SIP revisions by making clear from the title of the section that it applies to both SIP 

revisions and progress reports. Within §51.309(c)(10), amendments are proposed that would 

preserve the existing requirement that the progress reports due in 2013 were to take the form of 

SIP revisions, but direct the reader to the provisions of §51.308(g) for subsequent progress 

reports. In similar fashion, §51.309(c)(10)(i) and (ii) would be amended to specifically refer to 
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the 2013 progress reports, while §51.309(c)(10)(iii) would point to §51.308(g) for subsequent 

progress reports. Section 51.309(c)(10)(iv) is proposed to be added to indicate that subsequent 

progress reports are subject to the requirements of §51.308(h) regarding determinations of 

adequacy of existing SIPs. 

 A final change in section 51.309 appears in §51.309(g)(2)(iii). This change is purely to 

correct a typographical error and the EPA will therefore not consider comments on this 

subsection.

V. Environmental Justice Considerations

The EPA believes this action would not have disproportionately high and adverse human 

health, well-being or environmental effects on minority, low-income or indigenous populations 

because it would not negatively affect the level of protection provided to human health, wellbeing or the environment under the CAA’s visibility protection program. When promulgated, 

these proposed regulations will revise procedural and timing aspects of the SIP requirements for 

visibility protection but will not substantively change the requirement that SIPs provide for 

reasonable progress towards the goal of natural visibility conditions. These SIP requirements are 

designed to protect all segments of the general population. 

The EPA acknowledges that the proposed delay in submitting SIP revisions from 2018 to 

2021 might cause delays in when sources must comply with any new requirements. However, 

because neither the CAA nor the existing Regional Haze Rule set specific deadlines for when 

sources must comply with any new requirements in a state’s next periodic comprehensive SIP 

revision, states have substantial discretion in establishing reasonable compliance deadlines for 

measures in their SIPs. Given this, we expect to see a range of compliance deadlines in the next 

round of regional haze SIPs from early in the second implementation period to 2028, depending 
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on the types of measures adopted, whether or not these proposed rule changes are finalized. 

Thus, the EPA believes the delay in the periodic comprehensive SIP revision submission 

deadline from 2018 to 2021 will not meaningfully reduce the overall progress towards better 

visibility made by the end of 2028 and will not meaningfully adversely affect environmental 

protection for all general segments of the population. 

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: 

Improving Regulation and Regulatory Review 

This action is a significant regulatory action that was submitted to the OMB for review 

because it raises novel policy issues. Any changes made in response to OMB recommendations 

have been documented in the docket. 

B. Paperwork Reduction Act (PRA) 

 The information collection activities in this proposed rule have been submitted for 

approval to the OMB under the PRA. The Information Collection Request (ICR) document that 

the EPA prepared has been assigned the EPA ICR number 1813.10, OMB Control No. 2060-

0421. You can find a copy of the ICR in the docket for this rule, and it is briefly summarized 

here. 

 The EPA is proposing these amendments to requirements for state regional haze planning 

to change the requirements that must be met by states in developing regional haze SIPs, periodic 

comprehensive SIP revisions, and progress reports for regional haze. The main intended effects 

of this rulemaking are to provide states with additional time to submit regional haze plans for the 

second implementation period and to provide states with an improved schedule and process for 

progress report submission. Further reductions in burden on states include this proposal’s 
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removal of the requirement for progress reports to be SIP revisions, clarifying that states are not 

required to project emissions inventories as part of preparing a progress report, and relieving the 

state of the need to review its visibility monitoring strategy within the context of the progress 

report. With all of these proposed changes considered, the overall burden on states would 

represent a reduction compared to what would otherwise occur if the provisions of the current 

rule were to stay in place. Total estimated burden is estimated to be reduced from 10,307 hours 

(per year) to 5,974 hours (per year), and total estimated cost is expected to be reduced from 

$510,498 (per year) to $295,876 (per year). All states are required to submit regional haze SIPs 

and progress reports under this rule. 

Respondents/affected entities: All state air agencies. 

Respondent’s obligation to respond: Mandatory, in accordance with the provisions of the 1999 

Regional Haze Rule.

Estimated number of respondents: 52: 50 states, District of Columbia and U.S. Virgin Islands. 

Frequency of response: Approximately every 10 years (SIP) and approximately every 10 years 

(progress report).

Total estimated burden: 5,8405,974 hours (per year). Burden is defined at 5 CFR 1320.3(b). 

Total estimated cost: $289,238295,876 (per year), includes $0 annualized capital or operation & 

maintenance costs. 

 An agency may not conduct or sponsor, and a person is not required to respond to, a 

collection of information unless it displays a currently valid OMB control number. The OMB 

control numbers for the EPA's regulations in 40 CFR are listed in 40 CFR part 9. 
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Submit your comments on the agency’s need for this information, the accuracy of the 

provided burden estimates and any suggested methods for minimizing respondent burden to the 

EPA using the docket identified at the beginning of this rule. You may also send your ICRrelated comments to OMB’s Office of Information and Regulatory Affairs via email to 

orira_submissions@omb.eop.gov, Attention: Desk Officer for the EPA. Since OMB is required 

to make a decision concerning the ICR between 30 and 60 days after receipt, OMB must receive 

comments no later than [INSERT DATE 30 DAYS AFTER PUBLICATION IN THE 

FEDERAL REGISTER]. The EPA will respond to any ICR-related comments in the final rule. 

C. Regulatory Flexibility Act (RFA) 

I certify that this action will not have a significant economic impact on a substantial 

number of small entities under the RFA. This action will not impose any requirements on small 

entities. Entities potentially affected directly by this proposal include state governments, and for 

the purposes of the RFA, state governments are not considered small government. Tribes may 

choose to follow the provisions of the Regional Haze Rule but are not required to do so. Other 

types of small entities are not directly subject to the requirements of this rule. The EPA continues 

to be interested in the potential impacts of the proposed rule on small entities and welcomes 

comments on issues related to such impacts. 

D. Unfunded Mandates Reform Act (UMRA) 

This action does not contain any unfunded mandate as described in UMRA, 2 U.S.C. 

1531-1538, and does not significantly or uniquely affect small governments. This action imposes 

no enforceable duty on any state, local or tribal governments or the private sector. The CAA 

imposes the obligation for states to submit regional haze SIPs. In this rule, the EPA is proposing 

to revise those requirements in a manner that would not increase the obligation of any state, local 
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or tribal governments or the private sector. In this rule, the EPA is also proposing to extend the 

reasonably attributable visibility impairment certification provisions to some additional states, 

but these states are not small governments and any mandate on the private sector would be 

indirect since this rule does not mandate how an affected state should address such a 

certification. Therefore, this action is not subject to the requirements of sections 202, 203 and 

205 of the UMRA. 

E. Executive Order 13132: Federalism 

This action does not have federalism implications. It will not have substantial direct 

effects on the states, on the relationship between the national government and the states, or on 

the distribution of power and responsibilities among the various levels of government. The 

requirement to submit regional haze SIPs is mandated by the CAA. Thus, Executive Order 13132 

does not apply to these proposed regulations. 

In the spirit of Executive Order 13132 and consistent with the EPA policy to promote 

communications between the EPA and state and local governments, the EPA has already 

consulted extensively with state air agency officials prior to this proposal. The EPA specifically 

solicits comments on this proposed action from state and local officials. In addition, the EPA 

intends to meet with organizations representing state and local officials during the comment 

period for this action. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments 

This proposed action does not have tribal implications as specified in Executive Order 

13175. It would not have a substantial direct effect on one or more Indian tribes. Furthermore, 

these proposed regulation revisions do not affect the relationship or distribution of power and 

responsibilities between the federal government and Indian tribes. The CAA and the TAR 
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establish the relationship of the federal government and tribes in characterizing air quality and 

developing plans to protect visibility in Class I areas. Thus, Executive Order 13175 does not 

apply to this action. 

Although Executive Order 13175 does not apply to this action, the EPA solicits comment 

on this proposed action from tribal officials. The EPA also intends to offer to consult with any 

tribal government to discuss this proposal. See also section III.B.5 for further discussion 

regarding the role of tribes in visibility protection. 

G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks 

The EPA interprets Executive Order 13045 as applying only to those regulatory actions 

that concern environmental health or safety risks that the EPA has reason to believe may 

disproportionately affect children, per the definition of “covered regulatory action” in section 2-

202 of the Executive Order. This action is not subject to Executive Order 13045 because it does 

not concern an environmental health risk or safety risk. 

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy 

Supply, Distribution or Use 

This action is not a “significant energy action” because it is not likely to have a 

significant adverse effect on the supply, distribution or use of energy.

I. National Technology Transfer and Advancement Act

This rulemaking does not involve technical standards. 

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations 

The EPA believes the human health or environmental risk addressed by this action will 

not have disproportionately high and adverse human health or environmental effects on minority, 
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low-income or indigenous populations. The results of our evaluation are contained in section V 

of this document. 

VII. Statutory Authority 

 The statutory authority for this action is provided by 42 U.S.C. 7403, 7407, 7410 and 

7601. 
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Page 85105 of 14220 - Protection of Visibility: Amendments to Requirements for State 

Plans 

List of Subjects 

40 CFR Part 51 

Environmental protection, Administrative practice and procedure, Air pollution control, Nitrogen 

dioxide, Particulate matter, Sulfur oxides, Transportation, Volatile organic compounds. 

40 CFR Part 52 

Environmental protection, Administrative practice and procedure, Air pollution control, 

Incorporation by reference, Nitrogen dioxide, Particulate matter, Sulfur oxides, Transportation, 

Volatile organic compounds. 

__________________________________ 

Dated: 

__________________________________ 

Gina McCarthy, 

Administrator. 

 
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For the reasons stated in the preamble, Title 40, Chapter I of the Code of Federal Regulations is 

proposed to be amended as follows: 

PART 51–-REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL 

OF IMPLEMENTATION PLANS 

1. The authority citation for part 51 continues to read as follows: 

Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q. 

2. In §51.300, revise paragraph (b) to read as follows: 

§51.300 Purpose and applicability. 

* * * * * 

(b) Applicability—The provisions of this subpart are applicable to all States as defined in section 

302(d) of the Clean Air Act (CAA) except Guam, Puerto Rico, American Samoa, and the 

Northern Mariana Islands. 

* * * * * 

3. In §51.301: 

a. Add definitions for “Clearest days,” “Deciview index,” “End of the applicable implementation 

period,” “Natural visibility conditions,” “Prescribed fire,” and “Visibility,” “Wildfire,” and 

“Wildland.” 
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b. Revise the definitions for “Deciview,” “Federal Class I area,” “Least impaired days,” 

“Mandatory Class I Federal Area,” “Most impaired days,” “Reasonably attributable,” and 

“Visibility impairment.” 

The revisions and additions read as follows: 

§51.301 Definitions. 

* * * * * 

Clearest days means the twenty percent of monitored days in a calendar year with the lowest 

values of the deciview index. 

Deciview is the unit of measurement on the deciview index scale for quantifying in a standard 

manner human perceptions of visibility. 

Deciview index means a value for a day that is derived from calculated or measured light 

extinction, such that uniform increments of the index correspond to uniform incremental changes 

in perception across the entire range of conditions, from pristine to very obscured. The deciview 

index is calculated based on the following equation (for the purposes of calculating deciview

using IMPROVE data, the atmospheric light extinction coefficient must be calculated from 

aerosol measurements and an estimate of Rayleigh scattering): 

Deciview index=10 lne (bext/10 Mm−1). 

bext=the atmospheric light extinction coefficient, expressed in inverse megameters (Mm−1). 

End of the applicable implementation period means December 31 of the year in which the next 

periodic comprehensive implementation plan revision is due under §51.308(f). 

* * * * * 
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Federal Class I area or Class I Federal area means any Federal land that is classified or 

reclassified Class I. Mandatory Federal Class I areas are identified in part 81, subpart D. Other 

Federal Class I areas are identified in part 52 of this title. 

* * * * * 

Least impaired days means the twenty percent of monitored days in a calendar year with the 

lowest amounts of visibility impairment. 

* * * * * 

Mandatory Class I Federal Area or Mandatory Federal Class I Area means any area identified 

in part 81, subpart D of this title. 

Most impaired days means the twenty percent of monitored days in a calendar year with the 

highest amounts of visibility impairment. 

* * * * * 

Natural visibility conditions means visibility (light extinction, visual range, contrast, coloration, 

and texture) that would have existed under natural conditions. Natural visibility conditions vary 

with time and location, and are estimated or inferred rather than directly measured. 

* * * * *

Prescribed fire means any fire intentionally ignited by management actions in accordance with 

applicable laws, policies, and regulations to meet specific land or resource management 

objectives. 

* * * * * 
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Reasonably attributable means attributable by visual observation or any other appropriate 

technique. 

* * * * * 

Visibility means the degree of perceived clarity when viewing objects at a distance. Visibility

includes perceived changes in depends on light extinction, visual range, contrast, or coloration, 

and texture of elements in a scene. 

Visibility impairment means any humanly perceptible difference between actual visibility 

conditions and natural visibility conditions. Because natural visibility conditions can only be 

estimated or inferred, visibility impairment also is estimated or inferred rather than directly 

measured. 

* * * * * 

Wildfire means any fire started by an unplanned ignition caused by lightning; volcanoes; other 

acts of nature; unauthorized activity; or accidental, human-caused actions, or a prescribed fire 

that has been declared to be a wildfire. A wildfire that predominantly occurs on wildland is a 

natural event. 

Wildland means an area in which human activity and development is essentially non-existent, 

except for roads, railroads, power lines, and similar transportation facilities. Structures, if any, 

are widely scattered.

* * * * * 

4. In §51.302: 

a. Revise the section heading. 
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b. Revise paragraphs (a), (b), and (c). 

c. Add paragraph (d). 

The revisions and addition read as follows: 

§51.302 Reasonably attributable visibility impairment. 

(a) The affected Federal Land Manager may certify, at any time, that there exists reasonably 

attributable impairment of visibility in any mandatory Class I Federal area and identify which 

single source or small number of sources is responsible for such impairment. The affected 

Federal Land Manager will provide the certification to the State in which the impairment occurs 

and the State(s) in which the source(s) is located.

(b) The State(s) shall revise its regional haze implementation plan, in accordance with the 

schedules set forth in paragraphs (d)(1) and (d)(2) of this section, to include for each source or 

small number of sources that the Federal Land Manager has identified in whole or in part for 

reasonably attributable visibility impairment as part of a certification under paragraph (a) of this 

section: 

(1) A determination, based on the factors set forth in §51.308(d)(1)(i)(A), of the control 

measures, if any, that are necessary with respect to the source or sources in order for the plan to 

make reasonable progress toward natural visibility conditions in the affected Class I Federal 

area; 

(2) Emission limitations that reflect the degree of emission reduction achievable by such control 

measures and schedules for compliance as expeditiously as practicable; and 
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(3) Monitoring, recordkeeping, and reporting requirements sufficient to ensure the enforceability 

of the emission limitations. 

(c) If a source that the Federal Land Manager has identified as responsible in whole or in part for 

reasonably attributable visibility impairment as part of a certification under paragraph (a) of this 

section is a BART-eligible source, and if there is not in effect as of the date of the certification a

fully or conditionally approved implementation plan addressing the BART requirement for that 

source (which existing plan may incorporate either source-specific emission limitations 

reflecting the emission control performance of BART, an alternative program to address the 

BART requirement under §51.308(e)(2), (3), and (4), or for sources of SO2 a program approved 

under paragraph §51.309(d)(4)), then the State shall revise its regional haze implementation plan 

to meet the requirements of §51.308(e) with respect to that source, taking into account current 

conditions related to the factors listed in §51.308(e)(1)(ii)(A). This requirement is in addition to 

the requirement of paragraph (b) of this section. 

(d)(1) For any existing reasonably attributable visibility impairment the Federal Land Manager 

certifies to the State(s) under paragraph (a) of this section more than 2 years prior to the due date 

for a regional haze implementation plan revision required under §51.308(f), the State(s) shall 

include the elements described in paragraphs (b) and (c) in such revision and such elements shall 

be considered a required part of such revision. 

(2) For any existing reasonably attributable visibility impairment the Federal Land Manager 

certifies to the State(s) under paragraph (a) of this section less than 2 years prior to the due date 

for a regional haze implementation plan revision required under §51.308(f), but no more than 6 

months subsequent to that due datethe submission date of that implementation plan revision or 
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no more than 6 months subsequent to a further plan revision that changes the emission limitation 

for the subject source, the State(s) shall submit a revision to its regional haze implementation 

plan that includes the elements described in paragraph (b) and (c) no later than 2 years after the 

date of the certification. The State(s) is not required at that time to also revise its reasonable 

progress goals to reflect the additional emission reductions required from the source or sources. 

5. In §51.304: 

a. Revise paragraphs (a), (b), and (c). 

b. Remove and reserve paragraph (d). 

The revisions read as follows: 

§51.304 Identification of integral vistas. 

(a) Federal Land Managers were required to identify any integral vistas on or before December 

31, 1985, according to criteria the Federal Land Managers developed. These criteria must have 

included, but were not limited to, whether the integral vista was important to the visitor's visual 

experience of the mandatory Class I Federal area. 

(b) The following integral vistas were identified by Federal Land Managers: at Roosevelt 

Campobello International Park, from the observation point of Roosevelt cottage and beach area, 

the viewing angle from 244 to 256 degrees; and at Roosevelt Campobello International Park, 

from the observation point of Friar’s Head, the viewing angle from 154 to 194 degrees. 

(c) The State must list in its implementation plan any integral vista listed in paragraph (b) of this 

section. 

(d) [Reserved] 
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6. Section 51.305 is revised to read as follows: 

§51.305 Monitoring for reasonably attributable visibility impairment. 

For the purposes of addressing reasonably attributable visibility impairment, if the 

Administrator, Regional Administrator, or the affected Federal Land Manager has advised a 

State containing a mandatory Class I Federal area of a need for monitoring to assess reasonably 

attributable visibility impairment at a mandatory Class I Federal area in addition to the 

monitoring currently being conducted to meet the requirements of §51.308(d)(4), the State must 

include in the next implementation plan revision to meet the requirement of §51.308(f) an 

appropriate strategy for evaluating reasonably attributable visibility impairment in the mandatory 

Class I Federal area by visual observation or other appropriate monitoring techniques. Such 

strategy must take into account current and anticipated visibility monitoring research, the 

availability of appropriate monitoring techniques, and such guidance as is provided by the 

Agency. 

7. Section 51.306 is removed and reserved. 

§51.306 [Removed and Reserved] 

8. In §51.307, revise paragraphs (a) introductory text and (b) to read as follows: 

§51.307 New source review. 

(a) For purposes of new source review of any new major stationary source or major modification 

that would be constructed in an area that is designated attainment or unclassified under section 

107(d) of the CAA, the State plan must, in any review under §51.166 with respect to visibility 

protection and analyses, provide for: 
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* * * * * 

(b) * * * 

(1) That may have an impact on any integral vista of a mandatory Class I Federal area listed in 

§51.304(b), or 

(2) That proposes to locate in an area classified as nonattainment under section 107(d)(1) of the 

Clean Air Act that may have an impact on visibility in any mandatory Class I Federal area. 

* * * * * 

9. In §51.308: 

a. Add paragraphs (c), (f)(4), (f)(5), (f)(6), (g)(3)(i)(A), (g)(3)(i)(B), (g)(3)(ii)(A), (g)(3)(ii)(B), 

(g)(3)(iii)(A), and (g)(3)(iii)(B), and (g)(7). 

b. Revise paragraphs (b), (d)(2)(iv), (d)(3), (e)(2)(v), (e)(4), (e)(5), (f), (g) introductory text, 

(g)(3), (g)(4), (g)(5), (g)(6), (h) introductory text, (h)(1), (i)(2), (i)(3), and (i)(4). 

c. Remove paragraphs (d)(2)(iv)(A), (d)(2)(iv)(B), and (g)(7). 

The revisions and additions read as follows: 

§51.308 Regional haze program requirements. 

* * * * * 

(b) When are the first implementation plans due under the regional haze program? Except as 

provided in §51.309(c), each State identified in §51.300(b) must submit, for the entire State, an 

implementation plan for regional haze meeting the requirements of paragraphs (d) and (e) of this 

section no later than December 17, 2007. 
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(c) What is the relationship between requirements for regional haze and requirements for 

reasonably attributable visibility impairment? A State must address any reasonably attributable 

visibility impairment certified by a Federal Land Manager under §51.302(a) in its regional haze 

implementation plan, as required by §51.302(b)-(d). A State must also meet the requirements of 

§51.305 if the Administrator, Regional Administrator, or the Federal Land Manager has advised 

a State under §51.305 of a need for additional monitoring to assess reasonably attributable 

visibility impairment at a mandatory Class I Federal area. 

(d) * * * 

(2) * * * 

(iv) For the first implementation plan addressing the requirements of paragraphs (d) and (e) of 

this section, the number of deciviews by which baseline conditions exceed natural visibility 

conditions for the most impaired and least impaired days. 

(3) Long-term strategy for regional haze. Each State listed in §51.300(b) must submit a longterm strategy that addresses regional haze visibility impairment for each mandatory Class I 

Federal area within the State and for each mandatory Class I Federal area located outside the 

State that may be affected by emissions from the State. The long-term strategy must include 

enforceable emissions limitations, compliance schedules, and other measures as necessary to 

achieve the reasonable progress goals established by States having mandatory Class I Federal 

areas. In establishing its long-term strategy for regional haze, the State must meet the following 

requirements: 

* * * * * 

(e) * * * 
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(2) * * * 

(v) At the State's option, a provision that the emissions trading program or other alternative 

measure may include a geographic enhancement to the program to address the requirement under 

§51.302(b) related to reasonably attributable impairment from the pollutants covered under the 

emissions trading program or other alternative measure. 

* * * * * 

(4) A State subject to a trading program established in accordance with §52.38 or §52.39 under a 

Transport Rule Federal Implementation Plan need not require BART-eligible fossil fuel-fired 

steam electric plants in the State to install, operate, and maintain BART for the pollutant covered 

by such trading program in the State. A State that chooses to meet the emission reduction 

requirements of the Transport Rule by submitting a SIP revision that establishes a trading 

program and is approved as meeting the requirements of §52.38 or §52.39 also need not require 

BART-eligible fossil fuel-fired steam electric plants in the State to install, operate, and maintain 

BART for the pollutant covered by such trading program in the State. A State may adopt 

provisions, consistent with the requirements applicable to the State for a trading program 

established in accordance with §52.38 or §52.39 under the Transport Rule Federal 

Implementation Plan or established under a SIP revision that is approved as meeting the 

requirements of §52.38 or §52.39, for a geographic enhancement to the program to address any 

requirement under §51.302(b) related to reasonably attributable impairment from the pollutant 

covered by such trading program in that State. 

(5) After a State has met the requirements for BART or implemented emissions trading program 

or other alternative measure that achieves more reasonable progress than the installation and 
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operation of BART, BART-eligible sources will be subject to the requirements of paragraphs (d) 

and (f) of this section, as applicable, in the same manner as other sources. 

* * * * * 

(f) Requirements for periodic comprehensive revisions of implementation plans for regional 

haze. Each State identified in §51.300(b) must revise and submit its regional haze 

implementation plan revision to EPA by July 31, 2021, July 31, 2028, and every 10 years 

thereafter. The plan revision due on or before July 31, 2021 must include a commitment by the 

State to meet the requirements of paragraph (g). In each plan revision, the State 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. To meet the core requirements for regional haze for these areas, the State must 

submit an implementation plan containing the following plan elements and supporting 

documentation for all required analyses: 

(1) Calculations of baseline, current, and natural visibility conditions; progress to date; and the 

uniform rate of progress. For each mandatory Class I Federal area located within the State, the 

State must determine the following: 

(i) Baseline visibility conditions for the most impaired and clearest days. The period for 

establishing baseline visibility conditions is 2000 to 2004. For purposes of calculating and 

displaying the uniform rate of progress needed to attain natural visibility conditions by the end of 

2064, baseline visibility conditions must be associated with the last day of this period. Baseline 

visibility conditions must be calculated, using available monitoring data, by establishing the 

average deciview index for the most impaired and clearest days for each calendar year from 2000 
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to 2004. The baseline visibility conditions are the average of these annual values. For mandatory 

Class I Federal areas without onsite monitoring data for 2000-2004, the State must establish 

baseline values using the most representative available monitoring data for 2000-2004, in 

consultation with the Administrator or his or her designee. For mandatory Class I Federal areas 

with incomplete data availability for 2000-2004, the State must establish baseline values using 

the closest 5 complete years of monitoring data.

(ii) Natural visibility conditions for the most impaired and clearest days. Natural visibility 

conditions must be calculated by estimating the deciview index existing under natural conditions 

for the most impaired and clearest days, based on available monitoring information and 

appropriate data analysis techniques; and 

(iii) Current visibility conditions for the most impaired and clearest days. The period for 

calculating current visibility conditions is the most recent 5-year period for which data are 

available. Current visibility conditions must be calculated based on the annual average level of 

visibility impairment for the most impaired and clearest days for each of these 5 years. Current 

visibility conditions are the average of these annual values. 

(iv) Progress to date for the most impaired and clearest days. Actual progress made towards 

natural conditions since the baseline period, and actual progress made during the previous 

implementation period up to and including to the period for calculating current visibility 

conditions, for the most impaired and clearest days, must be calculated. 

(v) Difference between current visibility conditions and natural visibility conditions. The number 

of deciviews by which current visibility conditions exceed natural visibility conditions, for the 

most impaired and clearest days, must be calculated. 
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(vi) Uniform rate of progress. (A) The uniform rate of progress needed to attain natural visibility 

conditions by the end of 2064 for each mandatory Class I Federal area in the State must be 

calculated. To calculate this uniform rate of progress, the State must compare baseline visibility 

conditions to natural visibility conditions in the mandatory Class I Federal area and determine 

the uniform rate of visibility improvement (measured in deciviews of improvement per year) that 

would need to be maintained during each implementation period in order to attain natural 

visibility conditions by the end of 2064.

(B) The State may submit a request to the Administrator seeking an adjustment to the uniform 

rate of progress for a mandatory Class I Federal area to account for impacts from (1) 

anthropogenic sources outside the United States and/or (2) wildland prescribed fires that were 

conducted with the objective to establish, restore, and/or maintain sustainable and resilient 

wildland ecosystems, to reduce the risk of catastrophic wildfires, and/or to preserve endangered 

or threatened species during which appropriate basic smoke management practices were applied. 

To calculate the proposed adjustment, the State must add the estimated impacts to natural 

visibility conditions and compare the resulting value to baseline visibility conditions. If the 

Administrator determines that the State has estimated the impacts from anthropogenic sources 

outside the United States or wildland prescribed fires using scientifically valid data and methods, 

the Administrator may approve the proposed adjustment to the uniform rate of progress for use 

in the State’s implementation plan. 

(2) Long-term strategy for regional haze and reasonably attributable visibility impairment. Each 

State must submit a long-term strategy that addresses regional haze visibility impairment, and if 

necessary any reasonably attributable visibility impairment certified by the Federal Land 
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Manager under §51.302(a), for each mandatory Class I Federal area within the State and for each 

mandatory Class I Federal area located outside the State 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 achieve reasonable progress, as determined 

pursuant to (f)(2)(i) through (vi). In establishing its long-term strategy for regional haze, the 

State must meet the following requirements: 

(i) The State must consider and analyze emission reduction measures based on 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 major or minor 

stationary source or group of sources. The State must document the criteria used to determine 

which sources or groups of sources were evaluated, and how these four factors were taken into 

consideration in selecting the measures for inclusion in its long-term strategy. 

(ii) The State must consider the uniform rate of improvement in visibility, the emission reduction 

measures identified in (f)(2)(i), and additional measures being adopted by other contributing 

states in (f)(2)(iii) as needed to make reasonable progress towards natural visibility conditions 

for the period covered by the implementation plan. 

(iii) The State must consult with those States which may reasonably be anticipated to cause or 

contribute to visibility impairment in the mandatory Class I Federal area. 

(A) Contributing States. Where the State has emissions that are reasonably anticipated to 

contribute to visibility impairment in any mandatory Class I Federal area located in another State 

or States, the State must consult with the other State(s) in order to develop coordinated emission 

management strategies. The State must demonstrate that it has included in its implementation 
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plan all measures necessary to obtain its share of the emission reductions needed to provide for 

reasonable progress towards natural visibility conditions in the mandatory Class I Federal area 

located in the other State or States. If the State has participated in a regional planning process, 

the State must also ensure that it has included all measures needed to achieve its apportionment 

of emission reduction obligations agreed upon through that process. 

(B) States affected by contributing States. A State with a mandatory Class I Federal area must 

consult with any other State having emissions that are reasonably anticipated to contribute to 

visibility impairment in that area regarding the emission reductions needed in each State to 

provide for reasonable progress towards natural visibility conditions in that area. If the State has 

participated in a regional planning process, the State must ensure it has included all measures 

needed to achieve its apportionment of emission reduction obligations agreed upon through that 

process. 

(C) In any situation in which a State cannot agree with another State or group of States on the 

emission reductions needed for reasonable progress towards natural visibility conditions in any 

mandatory Class I Federal area, each involved State must describe in its submittal the actions 

taken to resolve the disagreement. In reviewing the State's implementation plan submittal, the 

Administrator will take this information into account in determining whether the State's 

implementation plan provides for reasonable progress towards natural visibility conditions at 

each mandatory Class I Federal area that is located in the State or that may be affected by 

emissions from the State. All substantive interstate consultations must be documented. 

(iv) As part of the demonstration required by (f)(2)(i), the State must document the technical 

basis, including information on the factors listed in (f)(2)(i) and modeling, monitoring, and 
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emissions information, on which the State is relying to determine the emission reductions from 

anthropogenic sources in the State that are necessary for achieving reasonable progress towards 

natural visibility conditions in each mandatory Class I Federal area it affects. The State may meet 

this requirement by relying on technical analyses developed by a regional planning process and 

approved by all State participants. The State must identify the baseline emissions inventory on 

which its strategies are based. The baseline emissions inventory year shall be the most recent 

year for which the State has submitted emission inventory information to the Administrator in 

compliance with the triennial reporting requirements of subpart A of this part unless the State 

adequately justifies the use of another inventory year. 

(v) The State must identify all anthropogenic sources of visibility impairment considered by the 

State in developing its long-term strategy and the criteria used to select the sources considered. 

The State should consider major and minor stationary sources, mobile sources, and area sources. 

(vi) The State must consider, at a minimum, the following factors in developing its long-term 

strategy: 

(A) Emission reductions due to ongoing air pollution control programs, including measures to 

address reasonably attributable visibility impairment; 

(B) Measures to mitigate the impacts of construction activities; 

(C) Emissions limitations and schedules for compliance to achieve the reasonable progress goal; 

(D) Source retirement and replacement schedules; 

(E) Smoke management techniques Basic smoke management practices for prescribed fire used 

for agricultural and forestry wildland vegetation management purposes and smoke management 

programs including plans as currently exist within the State for these purposes; 
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(F) Enforceability of emissions limitations and control measures; and 

(G) 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. 

(3) Reasonable progress goals. (i) A state in which a mandatory Class I Federal area is located 

must establish reasonable progress goals (expressed in deciviews) that reflect the visibility 

conditions that are projected to be achieved by the end of the applicable implementation period 

as a result of all enforceable emissions limitations, compliance schedules, and other measures 

required under paragraph (f)(2) and the implementation of other requirements of the CAA. The 

long-term strategy and the reasonable progress goals must provide for an improvement in 

visibility for the most impaired days and ensure no degradation in visibility for the clearest days

since the baseline period.

(ii)(A) If a State in which a mandatory Class I Federal area is located establishes a reasonable 

progress goal for the most impaired days that provides for a slower rate of improvement in 

visibility than the uniform rate of progress calculated under paragraph (f)(1)(vi) of this section, 

the State must demonstrate, based on the analysis required by paragraph (f)(2)(i) of this section, 

that there are no additional emission reduction measures for anthropogenic sources or groups of 

sources in the State that may reasonably be anticipated to contribute to visibility impairment in 

the Class I area that would be reasonable to include in the long-term strategy. The State must 

provide a robust demonstration, including documenting the criteria used to determine which 

sources or groups or 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 State must provide to the public for review as part of its implementation plan an 
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assessment of the number of years it would take to attain natural visibility conditions if visibility 

improvement were to continue at the rate of progress selected by the State as reasonable for the 

implementation period. 

(B) If a State contains sources which are reasonably anticipated to contribute to visibility 

impairment in a mandatory Class I Federal area in another State for which a demonstration by 

the other State is required under (f)(3)(ii)(A), the State must make the same demonstrateion that 

there are no additional emission reduction measures for anthropogenic sources or groups of 

sources in the State that may reasonably be anticipated to contribute to visibility impairment in 

the Class I area that would be reasonable to include in with respect to its own long-term strategy. 

 (iii) The reasonable progress goals established by the State are not directly enforceable but will 

be considered by the Administrator in evaluating the adequacy of the measures in the 

implementation plan in providing for reasonable progress towards achieving natural visibility 

conditions at that area. 

(iv) In determining whether the State’s goal for visibility improvement provides for reasonable 

progress towards natural visibility conditions, the Administrator will also evaluate the 

demonstrations developed by the State pursuant to paragraphs (f)(2) and (f)(3)(ii)(A) of this 

section and the demonstrations provided by other States pursuant to paragraphs (f)(2) and 

(f)(3)(ii)(B) of this section.

 (4) If the Administrator, Regional Administrator, or the affected Federal Land Manager has 

advised a State of a need for additional monitoring to assess reasonably attributable visibility 

impairment at a mandatory Class I Federal area in addition to the monitoring currently being 

conducted, the State must include in the plan revision an appropriate strategy for evaluating 
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reasonably attributable visibility impairment in the mandatory Class I Federal area by visual 

observation or other appropriate monitoring techniques. 

(5) So that the plan revision will serve also as a progress report, the State must address in the 

plan revision the requirements of paragraphs (g)(1), (g)(2), (g)(4), and (g)(5) of this section. 

However, the period to be addressed for these elements shall be the period since the past 

progress report. 

(6) Monitoring strategy and other implementation plan requirements. The State must submit 

with the implementation plan a monitoring strategy for measuring, characterizing, and reporting 

of regional haze visibility impairment that is representative of all mandatory Class I Federal 

areas within the State. Compliance with this requirement may be met through participation in the 

Interagency Monitoring of Protected Visual Environments network. The implementation plan 

must also provide for the following: 

(i) 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. 

(ii) 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. 

(iii) For a State with no mandatory Class I Federal areas, 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 in other States. 
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(iv) The implementation plan must provide for the reporting of all visibility monitoring data to 

the Administrator at least annually for each mandatory Class I Federal area in the State. To the 

extent possible, the State should report visibility monitoring data electronically. 

(v) A statewide inventory of emissions of pollutants that are reasonably anticipated to cause or 

contribute to visibility impairment in any mandatory Class I Federal area. The inventory must 

include emissions for a baseline year, emissions for the most recent year for which data are 

available, and estimates of future projected emissions. The State must also include a commitment 

to update the inventory periodically. 

(vi) Other elements, including reporting, recordkeeping, and other measures, necessary to assess 

and report on visibility. 

(g) Requirements for periodic reports describing progress towards the reasonable progress 

goals. Each State identified in §51.300(b) must periodically submit a report to the Administrator 

evaluating 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. The first progress report is due 5 years 

from submittal of the initial implementation plan addressing paragraphs (d) and (e) of this 

section. The first progress reports must be in the form of implementation plan revisions that 

comply with the procedural requirements of §51.102 and §51.103. Subsequent progress reports 

are due by January 31, 2025, July 31, 2033, and every 10 years thereafter. Subsequent progress 

reports must be made available for public inspection and comment for at least 60 days prior to 

submission to EPA and all comments received from the public must be submitted to EPA along 

with the subsequent progress report, along with an explanation of any changes to the progress 
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report made in response to these comments. Periodic progress reports must contain at a minimum 

the following elements: 

* * * * * 

(3) For each mandatory Class I Federal area within the State, the State must assess the following 

visibility conditions and changes, with values for most impaired, least impaired and/or clearest 

days as applicable expressed in terms of 5-year averages of these annual values. The period for 

calculating current visibility conditions is the most recent 5-year period preceding the required 

date of the progress report for which data are available as of a date 6 months preceding the 

required date of the progress report. 

(i)(A) Progress reports due before January 31, 2025. The current visibility conditions for the 

most impaired and least impaired days. 

(B) Progress reports due on and after January 31, 2025. The current visibility conditions for the 

most impaired and clearest days; 

(ii) (A) Progress reports due before January 31, 2025. The difference between current visibility 

conditions for the most impaired and least impaired days and baseline visibility conditions. 

(B) Progress reports due on and after January 31, 2025. The difference between current visibility 

conditions for the most impaired and clearest days and baseline visibility conditions. 

(iii) (A) Progress reports due before January 31, 2025. The change in visibility impairment for 

the most impaired and least impaired days over the period since the period addressed in the most 

recent plan required under paragraph (f) of this section. 
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(B) Progress reports due on and after January 31, 2025. The change in visibility impairment for 

the most impaired and clearest days over the period since the period addressed in the most recent 

plan required under paragraph (f) of this section. 

(4) An analysis tracking the change over the period since the period addressed in the most recent 

plan required under paragraph (f) of this section in emissions of pollutants contributing to 

visibility impairment from all sources and activities within the State. Emissions changes should 

be identified by type of source or activity. With respect to all sources and activities, the analysis 

must extend at least through the most recent year for which the state has submitted emission 

inventory information to the Administrator in compliance with the triennial reporting 

requirements of subpart A of this part. With respect to sources that report directly to a centralized 

emissions data system operated by the Administrator, the analysis must extend through the most 

recent year for which the Administrator has provided a State-level summary of such reported 

data or an internet-based tool by which the State may obtain such a summary. The State is not 

required to backcast previously reported emissions to be consistent with more recent emissions 

estimation procedures, and may draw attention to actual or possible inconsistencies created by 

changes in estimation procedures. 

(5) An assessment of any significant changes in anthropogenic emissions within or outside the 

State that have occurred since the period addressed in the most recent plan required under 

paragraph (f) of this section including whether or not these changes in anthropogenic emissions 

were anticipated in that most recent plan and whether they have limited or impeded progress in 

reducing pollutant emissions and improving visibility. 
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(6) For a state with a long-term strategy that includes a smoke management program for 

prescribed fires on wildland, a summary of the most recent periodic assessment of the smoke 

management program. 

(7) An assessment of whether the current implementation plan elements and strategies are 

sufficient to enable the State, or other States with mandatory Class I Federal areas affected by 

emissions from the State, to meet all established reasonable progress goals for the period covered 

by the most recent plan required under paragraph (f) of this section. 

(h) Determination of the adequacy of existing implementation plan. At the same time the State is 

required to submit any progress report to EPA in accordance with paragraph (g) of this section, 

the State must also take one of the following actions based upon the information presented in the 

progress report: 

(1) If the State determines that the existing implementation plan requires no further substantive 

revision at this time in order to achieve established goals for visibility improvement and 

emissions reductions, the State must provide to the Administrator a negative declaration that 

revision of the existing implementation plan is not needed at this time. 

* * * * * 

(i) * * * 

(2) The State must provide the Federal Land Manager with an opportunity for consultation, in 

person at a point early enough in the State’s technical and policy analyses of its long-term 

strategy emission reduction obligation and prior to development of reasonable progress goals 

planning the development of its long-term strategy so that information and recommendations 

provided by the Federal Land Manager can meaningfully inform the State’s development of the 
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long-term strategy. The opportunity for consultation will be deemed to have been early enough if 

the consultation has taken place and at least 60 120 days prior to holding any public hearing or 

other public comment opportunity on an implementation plan (or plan revision) or progress 

report for regional haze required by this subpart. The opportunity for consultation must be 

provided no less than 60 days prior to said public hearing or public comment opportunity. This 

consultation must include the opportunity for the affected Federal Land Managers to discuss 

their: 

* * * * * 

(3) In developing any implementation plan (or plan revision) or progress report, the State must 

include a description of how it addressed any comments provided by the Federal Land Managers. 

(4) The plan (or plan revision) must provide procedures for continuing consultation between the 

State and Federal Land Manager on the implementation of the visibility protection program 

required by this subpart, including development and review of implementation plan revisions and 

progress reports, and on the implementation of other programs having the potential to contribute 

to impairment of visibility in mandatory Class I Federal areas. 

10. In §51.309: 

a. Revise paragraphs (d)(4)(v), (d)(10), (d)(10)(i) introductory text, (d)(10)(ii) introductory text, 

and (g)(2)(iii). 

b. Add new paragraphs (d)(10)(iii) and (d)(10)(iv).

The revisions and additions read as follows: 

§51.309 Requirements related to the Grand Canyon Visibility Transport Commission. 
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* * * * * 

(d) * * * 

(4) * * * 

(v) Market Trading Program. The implementation plan must include requirements for a market 

trading program to be implemented in the event that a milestone is not achieved. The plan shall 

require that the market trading program be activated beginning no later than 15 months after the 

end of the first year in which the milestone is not achieved. The plan shall also require that 

sources comply, as soon as practicable, with the requirement to hold allowances covering their 

emissions. Such market trading program must be sufficient to achieve the milestones in 

paragraph (d)(4)(i) of this section, and must be consistent with the elements for such programs 

outlined in §51.308(e)(2)(vi). Such a program may include a geographic enhancement to the 

program to address the requirement under §51.302(b) related to reasonably attributable 

impairment from the pollutants covered under the program. 

* * * * * 

(10) Periodic implementation plan revisions and progress reports. Each Transport Region State 

must submit to the Administrator periodic reports in the years 2013 and as specified for 

subsequent progress reports in §51.308(g). The progress report due in 2013 must be in the form 

of an implementation plan revision that complies with the procedural requirements of §§51.102 

and 51.103. 

(i) The report due in 2013 will assess the area for reasonable progress as provided in this section 

for mandatory Class I Federal area(s) located within the State and for mandatory Class I Federal 

area(s) located outside the State that may be affected by emissions from within the State. This 
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demonstration may be based on assessments conducted by the States and/or a regional planning 

body. The progress report due in 2013 must contain at a minimum the following elements: 

* * * * * 

(ii) At the same time the State is required to submit the 5-year progress report due in 2013 to 

EPA in accordance with paragraph (d)(10)(i) of this section, the State must also take one of the 

following actions based upon the information presented in the progress report: 

* * * * * 

(iii) The requirements of §51.308(g) regarding requirements for periodic reports describing 

progress towards the reasonable progress goals apply to States submitting plans under this 

section, with respect to subsequent progress reports due after 2013. 

(iv) The requirements of §51.308(h) regarding determinations of the adequacy of existing 

implementation plans apply to States submitting plans under this section, with respect to 

subsequent progress reports due after 2013. 

* * * * * 

(g) * * * 

(2) * * * 

(iii) The Transport Region State may consider whether any strategies necessary to achieve the 

reasonable progress goals required by paragraph (g)(2) of this section are incompatible with the 

strategies implemented under paragraph (d) of this section to the extent the State adequately 

demonstrates that the incompatibility is related to the costs of the compliance, the time necessary 
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for compliance, the energy and non air quality environmental impacts of compliance, or the 

remaining useful life of any existing source subject to such requirements. 

PART 52 – APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS 

1. The authority citation for part 52 continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

2. In §52.26: 

a. Remove and reserve the entire section. 

The removal reads as follows: 

§52.26 [Reserved] 

* * * * * 

3. In §52.29: 

a. Remove and reserve the entire section. 

The removal reads as follows: 

§52.29 [Reserved] 

* * * * * 

4. In §52.29: 

a. Remove and reserve paragraph (b). 
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The removal reads as follows: 

§52.61 Visibility protection. 

* * * * * 

(b) [Reserved] 

* * * * * 

5. In §52.145: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

§52.145 Visibility protection. 

* * * * * 

(b) Regulations for visibility monitoring and new source review. The provisions of §§52.27 and 

52.28 are hereby incorporated and made part of the applicable plan for the State of Arizona. 

(c) [Reserved] 

* * * * * 

6. In §52.281: 

a. Remove and reserve paragraphs (b) and (e). 

The removals read as follows: 

§52.281 Visibility protection. 

* * * * * 

(b) [Reserved] 
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* * * * * 

(e) [Reserved] 

* * * * * 

7. In §52.344: 

a. Revise paragraph (b). 

The revision reads as follows: 

§52.344 Visibility protection. 

* * * * * 

(b) The Visibility NSR regulations are approved for industrial source categories regulated by the 

NSR and PSD regulations which have previously been approved by EPA. However, Colorado's 

NSR and PSD regulations have been disapproved for certain sources as listed in 40 CFR 

52.343(a)(1). The provisions of 40 CFR 52.28 are hereby incorporated and made a part of the 

applicable plan for the State of Colorado for these sources. 

* * * * * 

8. In §52.633: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

§52.633 Visibility protection. 

* * * * * 
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(b) Regulations for visibility monitoring and new source review. The provisions of §§52.27 and 

52.28 are hereby incorporated and made part of the applicable plan for the State of Hawaii. 

(c) [Reserved] 

* * * * * 

9. In §52.690: 

a. Remove and reserve paragraphs (b) and (c). 

The removals read as follows: 

§52.690 Visibility protection. 

* * * * * 

(b) [Reserved] 

(c) [Reserved] 

* * * * * 

10. In §52.1033: 

a. Remove and reserve paragraphs (a) and (c). 

The removals read as follows: 

§52.1033 Visibility protection. 

(a) [Reserved] 

* * * * * 

(c) [Reserved] 

* * * * * 

11. In §52.1183: 
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a. Revise paragraph (b). 

b. Remove and reserve paragraphs (a) and (c). 

The revision and removals read as follows: 

§52.1183 Visibility protection. 

(a) [Reserved]

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of Michigan. 

(c) [Reserved] 

* * * * * 

12. In §52.1236: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

§52.1236 Visibility protection. 

* * * * * 

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of Minnesota. 

(c) [Reserved] 

* * * * * 

13. In §52.1339: 

a. Remove and reserve paragraph (b). 
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The removal reads as follows: 

§52.1339 Visibility protection. 

* * * * * 

(b) [Reserved] 

* * * * * 

14. In §52.1387: 

a. Remove and reserve paragraph (b). 

The removal reads as follows: 

§52.1387 Visibility protection. 

* * * * * 

(b) [Reserved] 

* * * * * 

15. In §52.1488: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

§52.1488 Visibility protection. 

* * * * * 

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of Nevada except for 
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that portion applicable to the Clark County Department of Air Quality and Environmental 

Management. 

* * * * * 

16. In §52.1531: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

52.1531 Visibility protection. 

* * * * * 

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of New Hampshire. 

(c) [Reserved] 

* * * * * 

17. In §52.2132: 

a. Remove and reserve paragraphs (b) and (c). 

The removals read as follows: 

§52.2132 Visibility protection. 

* * * * * 

(b) [Reserved] 

(c) [Reserved] 

* * * * * 
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18. In §52.2179: 

a. Revise paragraph (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 

§52.2179 Visibility protection. 

* * * * * 

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of South Dakota. 

(c) [Reserved] 

* * * * * 

19. In §52.2304: 

a. Remove and reserve paragraph (b). 

The removal reads as follows: 

§52.2304 Visibility protection. 

* * * * * 

(b) [Reserved] 

* * * * *

20. In §52.2383: 

a. Revise paragraph (b). 

The revisions read as follows: 

§52.2383 Visibility protection. 
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* * * * * 

(b) Regulations for visibility monitoring and new source review. The provisions of §52.27 are 

hereby incorporated and made part of the applicable plan for the State of Vermont. 

* * * * * 

21. In §52.2452: 

a. Revise paragraph (a). 

b. Remove and reserve paragraphs (b) and (c). 

The revisions and removals read as follows: 

§52.2452 Visibility protection. 

(a) Reasonably Attributable Visibility Impairment. The requirements of section 169A of the 

Clean Air Act are not met because the plan does not include approvable measures for meeting 

the requirements of 40 CFR 51.305 for protection of visibility in mandatory Class I Federal 

areas. 

(b) [Reserved] 

(c) [Reserved] 

* * * * * 

22. In §52.2533: 

a. Revise paragraphs (a) and (b). 

b. Remove and reserve paragraph (c). 

The revisions and removal read as follows: 
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§52.2533 Visibility protection. 

(a) Reasonably Attributable Visibility Impairment. The requirements of section 169A of the 

Clean Air Act are not met because the plan does not include approvable measures for meeting 

the requirements of 40 CFR 51.305 and 51.307 for protection of visibility in mandatory Class I 

Federal areas. 

(b) Regulation for visibility monitoring and new source review. The provisions of §52.28 are 

hereby incorporated and made a part of the applicable plan for the State of West Virginia. 

(c) [Reserved] 

* * * * * 

23. In §52.2781: 

a. Remove and reserve paragraphs (b) and (c). 

The removals read as follows: 

§52.2781 Visibility protection. 

* * * * * 

(b) [Reserved] 

(c) [Reserved]