[Federal Register Volume 81, Number 86 (Wednesday, May 4, 2016)]
[Proposed Rules]
[Pages 26941-26976]
[FR Doc No: 2016-10228]

Vol. 81

Wednesday,

No. 86

May 4, 2016

Part IV

Environmental Protection Agency

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40 CFR Parts 51 and 52

 Protection of Visibility: Amendments to Requirements for State Plans;
Proposed Rule

Federal Register / Vol. 81 , No. 86 / Wednesday, May 4, 2016 /
Proposed Rules

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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.

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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
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 July 5, 2016. Public hearing. The EPA is holding a public
hearing concerning the proposed rule on May 19, 2016, in Washington,
DC. The last day to pre-register to speak at the hearing is May 17,
2016. 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 June 3, 2016.

ADDRESSES: Comments: Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-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 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 1117A, in Washington, DC. Identification is required. If your
driver's license is issued by American Samoa, Illinois or Missouri, 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 Information Collection Request (ICR), contact Mr.
Christopher Werner, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, by phone at<PHONE_NUMBER> or by email
at<EMAIL_ADDRESS>or Ms. Rhea Jones, Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, by phone
at<PHONE_NUMBER> or by email at<EMAIL_ADDRESS>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<PHONE_NUMBER> or by email
at<EMAIL_ADDRESS>
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
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 tribal \1\ 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 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.
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    \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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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.
    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 May 19, 2016, 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 1117A, 1201 Constitution Avenue NW.,
Washington, DC. It will convene at 9:00 a.m. and continue until the
earlier of 5:00 p.m. or 1 hour after the last registered speaker has
spoken. We have scheduled a lunch break from 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<PHONE_NUMBER>, fax number<PHONE_NUMBER>,
email address<EMAIL_ADDRESS>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 Web site at http://www.epa.gov/visibility 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.
    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 Missouri, 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 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/visibility.

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
    D. Impacts on Visibility From Anthropogenic Sources Outside the
U.S.
    E. Impacts on Visibility From Wildland Fires Within the U.S.
    F. Clarification of and Changes to the Required Content of
Progress Reports
    G. Changes to Reasonably Attributable Visibility Impairment
Provisions
    H. Consistency Revisions Related to Permitting of New and
Modified Major Sources
    I. Changes to FLM Consultation Requirements
    J. Extension of Next Regional Haze SIP Deadline From 2018 to
2021
    K. Changes to Scheduling of Regional Haze Progress Reports
    L. Changes to the Requirement that Regional Haze Progress
Reports Be SIP Revisions
    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 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), to
revise the due dates for progress reports and to remove the requirement
for progress 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.
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    \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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    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 long-term 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 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. Other 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.
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    \3\ When considering the ``time necessary for compliance,'' see
42 U.S.C. 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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    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.
    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 as-needed 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 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 and other 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.''
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    \4\ H.R. Rep. No. 294, 95th Cong. 1st Sess. at 205 (1977).
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    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 provided more data on
source-specific levels of visibility impairment, regional scale models
became refined, and our scientific knowledge about the relationships
between emitted air pollutants and visibility impairment improved.
    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 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 provide 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 be specifically addressed in the long-term
strategy for making reasonable progress toward the national goal of
natural visibility conditions. See existing Sec.  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 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 virtually all the time at most national park and wilderness
areas. The average visual range \5\ 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).
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    \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 = 10\6\]).
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    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 impacts from wildfire and/or dust
events. There are also some western areas where visibility has changed
only by a slight amount.
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    \6\ The deciview haze index (discussed in more detail in Section
III.B.3 of this document) 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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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 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. These findings triggered a requirement
for the EPA to promulgate FIPs within 2 years unless a state submitted
a SIP and the EPA approved that SIP within the 2-year period. CAA
section 110(c). Most states eventually submitted SIPs.\8\
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    \7\ This requirement does not apply to other U.S. territories
because they do not have mandatory Class I Federal areas and are too
distant from any such areas to affect them.
    \8\ All states and territories, with the exception of Hawaii,
Montana and the Virgin Islands, submitted initial regional haze
SIPs.
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    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 in achieving the 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 after the
date of the state's initial SIP submission. The 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
progress reports can be found in Section III.B.4 of this document.
    The 1999 Regional Haze Rule sought to improve efficiency and
transparency by requiring states to coordinate planning under the 1980
reasonably attributable visibility impairment provisions with 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 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 states 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 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 Regional Haze SIPs
    The Regional Haze Rule required the implementation plans due in
2007, which covered what we refer to as the first implementation
period, 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.
    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 sources \9\ procure, install and operate
BART. Under the Regional Haze Rule, the EPA directed states to conduct
BART determinations for any ``BART-eligible'' sources \10\ 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 gives states 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).
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    \9\ The set of ``major stationary sources'' potentially subject-
to-BART is listed in CAA section 169A(g)(7).
    \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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    States undertook the BART determination process during the first
implementation period. The BART requirement was a one-time requirement,
but BART-eligible sources may need to be re-assessed for additional
controls in future implementation periods under 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
other reasonable progress sources going forward. Consequently, we 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 they change over time. The Regional Haze Rule established the 24-
hour deciview haze index as the principal metric or unit for expressing
visibility on any particular day. See 70 FR 39104, 39118. The deciview
haze index is calculated from light extinction values and 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. Deciview 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 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 to
ensure more consistent terminology across sections of the Regional Haze
Rule.
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    \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: 3155/1047-32<IP_ADDRESS>6.
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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, states
must calculate visibility conditions at each Class I area for a 5-year
period just preceding each periodic comprehensive SIP revision.\12\ To
do this, the Regional Haze Rule requires states to determine average
visibility conditions (in deciviews) for the 20 percent least impaired
days and the 20 percent most impaired days over the 5-year period at
each of their Class I areas.
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    \12\ Under the current version of the Regional Haze Rule, states
must also periodically review progress in reducing impairment every
5 years.
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    States must also develop an estimate of natural visibility
conditions for the purpose of estimating progress toward the national
goal. 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 alternative 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\
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    \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.
    \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/RevisedIMPROVEAlgorithm3.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.
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    Baseline visibility conditions 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 conditions \15\ to the baseline conditions will indicate the
amount of progress that has been made.
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    \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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    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
``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 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).
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    \16\ Guidance for Tracking Progress Under the Regional Haze
Rule, September 2003, http://www3.epa.gov/ttnamti1/files/ambient/visible/tracking.pdf.
---------------------------------------------------------------------------

    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, Sec.  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 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 Sec.  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 long-term 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\
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    \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.C of 81
FR 296 (January 5, 2016).
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    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 natural visibility
conditions by 2064 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, Sec.  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 continued progress at the rate expected to be
achieved during that first period would not result in natural
conditions until a date after 2064.
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    \18\ The text of the Regional Haze Rule states the goal of
achieving ``natural visibility conditions.'' 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.''
The D.C. Circuit has affirmed that the Regional Haze Rule properly
interprets the visibility goal stated in the CAA as achievement of
``natural visibility conditions.'' American Corn Growers Ass'n v.
EPA, 291 F.3d 1, 25-27 (D.C. Cir. 2002).
---------------------------------------------------------------------------

    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 Sec.
51.308(d)(1)(i)(A) of the Regional Haze Rule require that states
determine ``reasonable progress'' by considering the four statutory
factors. Also, Sec.  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 long-term strategy: (1) Emission
reductions due to ongoing air pollution control programs, including
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 the 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 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 of this
document, 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 Sec.  51.305 for reasonably attributable visibility
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 of this document, 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 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.
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    \19\ While compliance with Sec.  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 Sec.  51.305 for reasonably
attributable visibility impairment.
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    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 of this document.
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 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 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 of this document.
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    \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 https://www.epa.gov/sites/production/files/2016-03/documents/haze_5year_4-10-13.pdf,
(hereinafter referred to as ``our 2013 Progress Report Guidance'').
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    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 of this document.
    In addition, as with SIPs, states are required to provide FLMs with
an opportunity for in-person 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.
    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 of this document.
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 government-to-government 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.
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    \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.
---------------------------------------------------------------------------

    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
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 Sec.  51.307 only as
needed to maintain consistency with revisions to other sections of 40
CFR part 50 subpart P.
---------------------------------------------------------------------------

    \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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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 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 Sec.  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
to make clear the connections between the existing long-strategy and
reasonable progress goal requirements. Although the regional haze SIPs
submitted by the states during the first planning period generally
demonstrated a clear understanding of the connections between these two
program elements, recent comments by some owners of industrial sources
and states have indicated confusion as to the meaning of these
provisions. The EPA's proposed revisions to Sec.  51.308(f) are
consistent with the EPA's long-standing interpretation \23\ of the
existing regulations at Sec.  51.308(d), but are organized in a more
logical fashion. While the new provisions track the language of the
existing regulations at Sec.  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. 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.
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    \23\ 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.C at 81
FR 308 (January 5, 2016).
---------------------------------------------------------------------------

    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, Sec.  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
Sec.  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 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. Finally, proposed subsection (f)(6) 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 Sec.  51.308(f)(2) that differs from the existing
language in Sec.  51.308(d)(3), but is intended to achieve the same
result. First, the EPA is proposing language in Sec.  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 Sec.
51.308(f)(2)(ii) that requires states to consider the URP and the
measures that contributing states are including in their long-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 Sec.  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.
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    \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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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 Sec.  51.308(f).

    The uniform rate of progress line starts at 2000-2004, for every
implementation period. The current text of Sec.  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 Sec.  51.308(f)
indicates that states must evaluate and reassess all elements required
by Sec.  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 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.
    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).
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    \25\ IMPROVE data from the 2000-2004 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.
---------------------------------------------------------------------------

    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, states 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 Sec.
51.308(f)(1)(i), does not appear in the current Sec.  51.308(d) because
at the time Sec.  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 Sec.
51.308(f)(3)(i) (and an accompanying definition of ``end of the
applicable implementation period'' added to Sec.  51.301) would make
clear that reasonable 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 Sec.  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
Sec.  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 ambiguous 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 provide further clarity,
we are proposing new rule text in revised Sec.  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.
---------------------------------------------------------------------------

    \26\ 64 FR 35730 (July 1, 1999).
---------------------------------------------------------------------------

    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 Sec.
51.308(f)(3)(ii).
    The current text of Sec.  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 Sec.  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 anthropogenic sources or groups of
sources in the state that 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 of 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 Sec.  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.
    To clarify and solidify the obligations of what we are referring to
as contributing states, Sec.  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 Sec.
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 Sec.
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 long-term 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 Sec.  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 Sec.  51.308(f)(5)
complements proposed changes regarding progress reports and the
proposal to eliminate separate progress reports being 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 Sec.  51.308(f)(2)(vi)(E) mirrors the existing Sec.
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 Sec.  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
Sec.  51.308(d)(3)(v)(E), the proposed Sec.  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 of this
document 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 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 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 Sec.  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 Sec.  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.
    Additionally, we propose definitions for the following previously
undefined terms be included in Sec.  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.
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    \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.''
---------------------------------------------------------------------------

    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 Sec.  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 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. In the
first approach, states would be required to select the 20 percent most
impaired days, i.e., the days 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. EPA also solicits comments
on additional approaches. 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 URP, 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
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 of this
document) 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 anthropogenic 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
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.C of this document), 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
accurate, 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 Sec.  51.308(f)(3)(ii) regarding a demonstration that there
are not additional emission reduction measures needed for reasonable
progress. However, we are not 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 a proposed provision
that would allow states with Class I areas significantly impacted by
international emissions 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
international impacts, only for the purpose of calculating the URP.\29\
We believe that this adjustment should be permitted only if the
Administrator determines the international impacts from anthropogenic
sources outside the United States were estimated using scientifically
valid data and methods. We are proposing specific rule text for this
purpose in Sec.  51.308(f)(1)(vi). In addition, we are proposing small
rule text changes in Sec.  51.308(f)(1)(i) and (vi) (compared to their
counterparts in Sec.  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,\30\ 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 comments on this proposed
rule 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.
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    \29\ 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 of this
document) 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.
    \30\ Contributing states may be affected because under proposed
Sec.  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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E. Impacts on Visibility From Wildland Fires Within the U.S.

    Fires on wildlands within the U.S. can significantly impact
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. 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 of this
document) 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. 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.
    An extensive discussion of the background on wildland fire
concepts, including 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 (i.e.,
basic smoke management practices), was presented in the recently
proposed revisions to the Exceptional Events rule (80 FR 72840,
November 20, 2015) and is not repeated here. We do wish to note,
however, that 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 Sec.  51.308(f)(2)(v)(E) would make a certain
state obligation depend on whether a ``smoke 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 Sec.  51.308(f)(2)(v)(E) to mean programs that include 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 Sec.
51.308(f)(2)(v)(E) triggered by the existence of these types of
programs.\31\
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    \31\ We note that the determining factor for the applicability
of proposed Sec.  51.308(f)(2)(v)(E) would be the existence of a
program and its elements, not whether the program has been
incorporated into the SIP as an enforceable measure or described in
the narrative portion of the SIP.
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    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 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 plan \32\ 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. These 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.
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    \32\ 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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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 as part of a
regional haze program. 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
of this document.
    Consideration of control measures for wildland wildfires. Because
wildland wildfires are considered natural events, emissions from
wildfires are natural emissions that contribute to natural visibility