[Federal Register Volume 84, Number 60 (Thursday, March 28, 2019)]
[Proposed Rules]
[Pages 11697-11711]
[FR Doc No: 2019-05861]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2015-0426; FRL-9990-62-Region 6]

Air Plan Approval; Arkansas; Regional Haze Five-Year Progress
Report State Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the
Environmental Protection Agency (EPA) is proposing to approve a State
Implementation Plan (SIP) submitted by the Governor through the
Arkansas Department of Environmental Quality (ADEQ) on June 2, 2015.
The SIP submittal addresses requirements of the federal regulations
that direct the State to submit a periodic report that assesses
progress toward reasonable progress goals (RPGs) established for
regional haze with a determination of adequacy of the existing
implementation plan.

DATES: Written comments must be received on or before April 29, 2019.

ADDRESSES: Submit comments, identified by Docket No. EPA-R06-OAR-2015-
0426, at https://www.regulations.gov or via email to
<EMAIL_ADDRESS>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 any information electronically that is considered
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 with multimedia
submissions and should include all discussion points desired. The EPA
will generally not consider comments or their contents located outside
of the primary submission (i.e. on the web, cloud, or other file
sharing systems). For additional submission methods, please contact
James E. Grady,<PHONE_NUMBER><EMAIL_ADDRESS>For the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket: The index to the docket for this action is available
electronically at www.regulations.gov and in hard copy at the EPA
Region 6, 1445 Ross Avenue, Suite 700, Dallas, Texas. While all
documents in the docket are listed in the index, some information may
be publicly available only at the hard copy location (e.g., copyrighted
material), and some may not be publicly available at either location
(e.g., CBI).

FOR FURTHER INFORMATION CONTACT: James E. Grady,<PHONE_NUMBER>;
<EMAIL_ADDRESS>To inspect the hard copy materials, please
schedule an appointment with Mr. Grady or Mr. Bill Deese at 214-665-
7253.

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' or
``our'' each mean ``the EPA.''

Table of Contents:

I. Background
    A. The Regional Haze Program
    B. Previous Actions on Arkansas Regional Haze
    C. Arkansas' Regional Haze Progress Report SIP Revision
II. Evaluation of Arkansas' Regional Haze Progress Report SIP
Revision
    A. Class I Areas
    B. Status of Implementation of Measures
    1. BART Controls
    2. Reasonable Progress Source Controls
    3. CAIR and CSAPR
    4. Source Retirement and Replacement Schedules
    5. Agriculture and Forestry Smoke Management
    6. Additional Federal Programs
    7. EPA's Conclusion on the Status of Implementation of Measures
    C. Emission Reductions From Implementation of Measures
    D. Visibility Conditions and Changes
    E. Emission Tracking
    F. Assessment of Changes Impeding Visibility Progress
    G. Assessment of Current Strategy To Meet RPGs
    H. Review of Visibility Monitoring Strategy
    I. Determination of Adequacy of Existing Implementation Plan
    J. Consultation With Federal Land Managers
III. The EPA's Proposed Action
IV. Statutory and Executive Order Reviews

I. Background

A. The Regional Haze Program

    Regional haze is visibility impairment that occurs over a wide
geographic area primarily from the pollution of fine particles
(PM2.5) emitted into the air.\1\ Fine particles causing haze
consist of sulfates (SO4\2\ -), nitrates
(NO3-), organics, elemental carbon (EC), and soil
dust.\2\ Airborne PM2.5 can scatter

and absorb the incident light and, therefore, lead to atmospheric
opacity and horizontal visibility degradation. Regional haze limits
visual distance and reduces color, clarity, and contrast of view.
PM2.5 can cause serious adverse health effects and mortality
in humans. It also contributes to environmental effects such as acid
deposition and eutrophication. Emissions that affect visibility include
a wide variety of natural and man-made sources. Reducing
PM2.5 and its precursor gases in the atmosphere is an
effective method of improving visibility. PM2.5 precursors
consist of sulfur dioxide (SO2), nitrogen oxides
(NOX), ammonia (NH3), and volatile organic
compounds (VOCs).
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    \1\ Fine particles are less than or equal to 2.5 microns
([micro]m) in diameter and usually form secondary in nature
indirectly from other sources. Particles less than or equal to 10
[micro]m in diameter are referred to as PM10. Particles
greater than PM2.5 but less than PM10 are
referred to as coarse mass. Coarse mass can contribute to light
extinction as well and is made up of primary particles directly
emitted into the air. Fine particles tend to be man-made, while
coarse particles tend to have a natural origin. Coarse mass settles
out from the air more rapidly than fine particles and usually will
be found relatively close to emission sources. Fine particles can be
transported long distances by wind and can be found in the air
thousands of miles from where they were formed.
    \2\ Organic carbon (OC) can be emitted directly as particles or
formed through reactions involving gaseous emissions. Elemental
carbon, in contrast to organic carbon, is exclusively of primary
origin and emitted by the incomplete combustion of carbon-based
fuels. Elemental carbon particles are especially prevalent in diesel
exhaust and smoke from wild and prescribed fires.
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    Data from the existing visibility monitoring network, ``Interagency
Monitoring of Protected Visual Environments'' (IMPROVE), shows that
visibility impairment caused by air pollution occurs virtually all of
the time at most national parks and wilderness areas. In 1999, the
average visual range \3\ in many Class I areas (i.e., national parks
and memorial parks, wilderness areas, and international parks meeting
certain size criteria) in the western United States was 100-150
kilometers (km), or about one-half to two-thirds of the visual range
that would exist under estimated natural conditions.\4\ In most of the
eastern Class I areas of the United States, the average visual range
was less than 30 km, or about one-fifth of the visual range that would
exist under estimated natural conditions. CAA programs have reduced
emissions of some haze-causing pollution, lessening some visibility
impairment and resulting in partially improved average visual
ranges.\5\
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    \3\ Visual range is the greatest distance, in km or miles, at
which a dark object can be viewed against the sky by a typical
observer.
    \4\ 64 FR 35715 (July 1, 1999).
    \5\ An interactive ``story map'' depicting efforts and recent
progress by EPA and states to improve visibility at national parks
and wilderness areas may be visited at: http://arcg.is/29tAbS3.
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    In section 169A of the 1977 CAA Amendments, Congress created a
program for protecting visibility in the nation's national parks and
wilderness areas. This section of the CAA establishes as a national
goal the prevention of any future, and the remedying of any existing,
visibility impairment in mandatory Class I Federal areas where
impairment results from manmade air pollution.\6\ Congress added
section 169B to the CAA in 1990 that added visibility protection
provisions, and the EPA promulgated final regulations addressing
regional haze as part of the 1999 Regional Haze Rule, which was most
recently updated in 2017.\7\ The Regional Haze Rule revised the
existing 1980 visibility regulations and established a more
comprehensive visibility protection program for Class I areas. The
requirements for regional haze, found at 40 CFR 51.308 and 51.309, are
included in the EPA's broader visibility protection regulations at 40
CFR 51.300-309. The regional haze regulations require states to
demonstrate reasonable progress toward meeting the national goal of a
return to natural visibility conditions for Class I areas both within
and outside states by 2064. The CAA requirement in section 169A(b)(2)
to submit a regional haze SIP applies to all fifty states, the District
of Columbia, and the Virgin Islands. States were required to submit the
first implementation plan addressing visibility impairment caused by
regional haze no later than December 17, 2007.\8\
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    \6\ Mandatory Class I Federal areas consist of national parks
exceeding 6,000 acres, wilderness areas and national memorial parks
exceeding 5,000 acres, and all international parks that were in
existence on August 7, 1977. The EPA, in consultation with the
Department of Interior, promulgated a list of 156 areas where
visibility was identified as an important value. The extent of a
mandatory Class I area includes subsequent changes in boundaries,
such as park expansions. Although states and tribes may designate
additional areas as Class I, the requirements of the visibility
program set forth in the CAA applies only to ``mandatory Class I
Federal areas.'' Each mandatory Class I Federal area is the
responsibility of a ``Federal Land Manager.'' When the term ``Class
I area'' is used in this action, it means ``mandatory Class I
Federal areas.'' [See 44 FR 69122, November 30, 1979 and CAA
Sections 162(a), 169A, and 302(i)].
    \7\ See the July 1, 1999 Regional Haze Rule final action (64 FR
35714), as amended on July 6, 2005 (70 FR 39156), October 13, 2006
(71 FR 60631), June 7, 2012 (77 FR 33656) and on January 10, 2017
(82 FR 3079).
    \8\ See 40 CFR 51.308(b). The EPA's regional haze regulations
require subsequent updates to the regional haze SIPs. 40 CFR
51.308(g)-(i).
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    Section 169A(b)(2)(A) of the CAA directs states to evaluate the use
of Best Available Retrofit Technology (BART) controls at certain
categories of existing major stationary sources \9\[thinsp]built
between 1962 and 1977. These large, often under-controlled, older
stationary sources are required to procure, install, and operate BART
controls to address visibility impacts from them. Under the Regional
Haze Rule, any of these BART-eligible sources \10\ that are reasonably
anticipated to cause or contribute to visibility impairment in a Class
I area are determined to be subject-to-BART.\11\ States are directed to
conduct BART determinations for each source classified as subject-to-
BART. 40 CFR 51.308(e)(1)(ii)(A) requires states (or EPA in the case of
a FIP) to identify the level of control representing BART after
considering the five statutory factors set out in CAA section
169A(g)(2). States must establish emission limits, a schedule of
compliance, and other measures consistent with the BART determination
process for each source subject-to-BART. In lieu of requiring source-
specific BART controls, states also have the flexibility to adopt
alternative measures, as long as the alternative provides greater
reasonable progress toward improving visibility than BART. Namely, the
alternative must be ``better than BART.'' \12\
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    \9\ See 42 U.S.C. 7491(g)(7) (listing the set of ``major
stationary sources'' potentially subject-to-BART).
    \10\ See 40 CFR 51 Appendix Y, II. How to Identify BART-eligible
Sources.
    \11\ Under the BART Guidelines, states may select a visibility
impact threshold, measured in deciviews (dv), below which a BART-
eligible source would not be expected to cause or contribute to
visibility impairment in any Class I area. The state must document
this threshold in the SIP and state the basis for its selection of
that value. Any source with visibility impacts that model above the
threshold value would be subject to a BART determination review. The
BART Guidelines acknowledge varying circumstances affecting
different Class I areas. States should consider the number of
emission sources affecting the Class I areas at issue and the
magnitude of the individual sources' impacts. Any visibility impact
threshold set by the state should not be higher than 0.5 dv. See 40
CFR 51, Appendix Y, section III.A.1.
    \12\ The required content of BART alternative measures is
codified at 40 CFR 51.308(e)(2).
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B. Previous Actions on Arkansas Regional Haze

    Arkansas submitted a regional haze SIP on September 9, 2008, to
address the requirements of the first regional haze implementation
period. On August 3, 2010, the State submitted a SIP revision with
mostly non-substantive changes that addressed Arkansas Pollution
Control and Ecology Commission (APCEC) Regulation 19 Chapter 15.\13\ On
September 27, 2011, the State submitted supplemental information to
address the regional haze requirements. The EPA collectively refers to
the original 2008 submittal and these revisions together as the 2008
Arkansas Regional Haze SIP. On March 12, 2012, the EPA partially
approved and partially disapproved the 2008 Arkansas Regional Haze
SIP.\14\ Specifically, the EPA disapproved

certain BART compliance dates; the State's identification of certain
BART-eligible sources and subject-to-BART sources; certain BART
determinations for NOX, SO2, and PM; the State's
reasonable progress analysis and RPGs; and a portion of the State's
long-term strategy (LTS). The remaining provisions of the 2008 Arkansas
Regional Haze SIP were approved. The final partial disapproval started
a two-year federal implementation plan (FIP) clock that obligated the
EPA to either approve a SIP revision or promulgate a FIP to address the
disapproved portions of the action.\15\ Because a SIP revision was not
received and since the FIP clock expired in April 2014, the EPA
promulgated a FIP (the Arkansas Regional Haze FIP) on September 27,
2016 to address the disapproved portions of the 2008 Arkansas Regional
Haze SIP.\16\ Among other things, the FIP established SO2,
NOX, and PM emission limits under the BART requirements for
nine units at six facilities: Arkansas Electric Cooperative Corporation
(AECC) Carl E. Bailey Plant Unit 1 Boiler; AECC John L. McClellan Plant
Unit 1 Boiler; SWEPCO Flint Creek Plant Boiler No. 1; Entergy Lake
Catherine Plant Unit 4 Boiler; Entergy White Bluff Plant Units 1 and 2
Boilers and the Auxiliary Boiler; and the Domtar Ashdown Mill Power
Boilers No. 1 and 2. The FIP also established SO2 and
NOX emission limits under the reasonable progress
requirements for the Entergy Independence Plant Units 1 and 2.
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    \13\ The September 9, 2008 SIP submittal included APCEC
Regulation 19, Chapter 15, which is the state regulation that
identified the BART-eligible and subject-to-BART sources in Arkansas
and established BART emission limits for subject-to-BART sources.
The August 3, 2010 SIP revision did not revise Arkansas' list of
BART-eligible and subject-to-BART sources or revise any of the BART
requirements for affected sources. Instead, it included mostly non-
substantive revisions to the state regulation.
    \14\ See the final action on March 12, 2012 (77 FR 14604).
    \15\ Under CAA section 110(c), EPA is required to promulgate a
FIP within 2 years of the effective date of a finding that a state
has failed to make a required SIP submission or has made an
incomplete submission, or of the date that EPA disapproves a SIP in
whole or in part. The FIP requirement is terminated only if a state
submits a SIP, and EPA approves that SIP as meeting applicable CAA
requirements before promulgating a FIP. CAA section 302(y) defines
the term ``federal implementation plan'' in pertinent part, as a
plan (or portion thereof) promulgated by EPA ``to fill all or a
portion of a gap or otherwise correct all or a portion of an
inadequacy'' in a SIP, and which includes enforceable emission
limitations or other control measures, means or techniques
(including economic incentives, such as marketable permits or
auctions or emissions allowances).
    \16\ See FIP final action (81 FR 66332) as corrected on October
4, 2016 (81 FR 68319).
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    Following petitions for reconsideration \17\ submitted by the
State, industry, and ratepayers, the EPA issued a partial
administrative stay of the effectiveness of the FIP for ninety days on
April 25, 2017.\18\ During that period, on July 12, 2017, the State
submitted a proposed SIP submittal (the Arkansas Regional Haze
NOX SIP revision) to address NOX BART
requirements for all EGUs and the reasonable progress requirements with
respect to NOX. These NOX provisions were
previously disapproved by the EPA in our 2012 final action for the 2008
Arkansas Regional Haze SIP. The Arkansas Regional Haze NOX
SIP submittal replaced all source-specific NOX BART
determinations established in the FIP with reliance upon the Cross-
State Air Pollution Rule (CSAPR) emissions trading program for ozone
(O3) season NOX as an alternative to
NOX BART. The SIP submittal addressed the NOX
BART requirements for Bailey Unit 1, McClellan Unit 1, Flint Creek
Boiler No. 1, Lake Catherine Unit 4; White Bluff Units 1 and 2, and the
Auxiliary Boiler. The revision did not address NOX BART for
Domtar Ashdown Mill Power Boilers No. 1 and 2. On February 12, 2018, we
took final action to approve the Arkansas Regional Haze NOX
SIP revision and to withdraw the corresponding parts of the FIP.\19\
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    \17\ See the docket associated with this proposed rulemaking for
a copy of the petitions for reconsideration and administrative stay
submitted by the State of Arkansas; Entergy Arkansas Inc., Entergy
Mississippi Inc., and Entergy Power LLC (collectively ``Entergy'');
AECC; and the Energy and Environmental Alliance of Arkansas (EEAA).
    \18\ 82 FR 18994.
    \19\ See 82 FR 42627 (September 11, 2017) for the proposed
approval. See also 83 FR 5915 and 83 FR 5927 (February 12, 2018) for
the final action.
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    The State submitted another SIP revision (the Arkansas Regional
Haze SO2 and PM SIP revision) on August 8, 2018, that
addressed most of the remaining parts of the 2008 Arkansas Regional
Haze SIP disapproved in 2012. The August 8, 2018 SIP submittal was
intended to replace the federal SO2 and PM BART
determinations for EGUs as well as the reasonable progress
determinations established in the FIP with the State's own
determinations. Specifically, the SIP revision addressed the applicable
SO2 and PM BART requirements for Bailey Unit 1;
SO2 and PM BART requirements for McClellan Unit 1;
SO2 BART requirements for Flint Creek Boiler No. 1;
SO2 BART requirements for White Bluff Units 1 and 2;
SO2, NOX, and PM BART requirements for the White
Bluff Auxiliary Boiler; \20\ and Lake Catherine Unit 4. The submittal
addressed the reasonable progress requirements for Independence Units 1
and 2 and all other sources in Arkansas. In addition, it established
revised RPGs for Arkansas' two Class I areas and revised the State's
long-term strategy provisions. The submittal did not address BART and
associated long-term strategy requirements for Domtar Ashdown Mill
Power Boilers No. 1 and 2. On November 30, 2018, we proposed approval
of the Arkansas Regional Haze SO2 and PM SIP revision and to
withdraw the corresponding parts of the FIP.\21\
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    \20\ The Arkansas Regional Haze SO2 and PM SIP
revision established a new NOX emission limit of 32.2 pph
for the Auxiliary Boiler to satisfy NOX BART and replace
the SIP determination that we previously approved in the Arkansas
Regional Haze NOX SIP revision. In the Arkansas Regional
Haze NOX SIP revision, ADEQ incorrectly identified the
Auxiliary Boiler as participating in the CSAPR trading program for
O3 season NOX to satisfy the NOX
BART requirements but the new source specific NOX BART
emission limit corrects that error.
    \21\ See 83 FR 62204 (November 30, 2018) for proposed approval.
The Arkansas Regional Haze SO2 and PM SIP revision also
addressed separate CAA requirements related to interstate visibility
transport under CAA section 110(a)(2)(D)(i)(II), but we did not
propose action on that part of the submittal.
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C. Arkansas' Regional Haze Progress Report SIP Revision

    Under 40 CFR 51.308(g), each state is required to submit a progress
report that evaluates progress toward the RPGs for each Class I area
within the state and each Class I area outside the state which may be
affected by emissions from within the state. In addition, 40 CFR
51.308(h) requires states to submit, at the same time as the progress
report, a determination of adequacy of the existing regional haze
implementation plan.\22\ The progress report for the first planning
period is due five years after submittal of the initial regional haze
SIP and must take the form of a SIP revision. Arkansas submitted its
initial regional haze SIP on September 9, 2008.
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    \22\ The Regional Haze Rule requires states to provide in the
progress report an assessment of whether the current
``implementation plan'' is sufficient to enable the states to meet
all established RPGs under 40 CFR 51.308(g). The term
``implementation plan'' is defined for purposes of the Regional Haze
Rule to mean any SIP, FIP, or Tribal Implementation Plan. As such,
the Agency may consider measures in any issued FIP as well as those
in a state's regional haze plan in assessing the adequacy of the
``existing implementation plan'' under 40 CFR 51.308(g) and (h).
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    On June 2, 2015, Arkansas submitted its progress report to the EPA
in the form of a SIP revision under 40 CFR 51.308. As described in
further detail in section II of this proposed rulemaking, to address
the progress report requirements, the State provided: (1) A description
of the status of measures in the approved regional haze SIP; (2) a
summary of emission reductions achieved; (3) an assessment of
visibility conditions for each Class I area in the state (and for two
Class I areas in Missouri); (4) an analysis tracking the changes in
emissions from sources and activities within the state; (5) an
assessment of any significant changes in anthropogenic emissions within
or outside the state that have limited or

impeded progress in reducing pollutant emissions and improving
visibility; (6) an assessment of whether the approved regional haze SIP
elements and strategies are sufficient to enable the State (and other
states with Class I areas affected by emissions from the state) to meet
all established RPGs; (7) a review of the State's visibility monitoring
strategy; and (8) a determination of adequacy of the existing
implementation plan.

II. Evaluation of Arkansas' Regional Haze Progress Report SIP Revision

    On June 2, 2015, the EPA received Arkansas' periodic report on
progress for the State's regional haze SIP in the form of a SIP
revision. That submission is the subject of this proposed approval. The
periodic report for the first implementation period assessed visibility
progress toward the 2018 RPGs for Class I areas in the state. It also
assessed visibility progress in general for two Class I areas in
Missouri that may be affected by emissions from within the state. The
progress report asserted that Arkansas was committed to remedying the
disapproved portions of the 2008 Arkansas Regional Haze SIP submission.
At this time, the Arkansas Regional Haze NOX SIP
revision,\23\ the Arkansas Regional Haze SO2 and PM SIP
revision (if EPA's proposed approval is finalized),\24\ and the
remaining part of the FIP that addresses the BART and associated long-
term strategy requirements for Domtar together fully address the
deficiencies of the 2008 Arkansas Regional Haze SIP. These deficiencies
were previously identified in 2012 by the EPA and acknowledged by ADEQ
in its June 2, 2015 progress report SIP. The 2018 Arkansas Regional
Haze SO2 and PM SIP submission provides more recent
visibility information in addition to the visibility data presented by
ADEQ in the 2015 progress report. The recent data shows visibility
improvement that is exceeding the revised visibility goals set for 2018
for the Arkansas Class I areas. Furthermore, up-to-date emission trends
indicate that SO2, NOX, and PM emissions have all
been decreasing. The EPA is, therefore, proposing to approve Arkansas'
progress report on the basis that it satisfies the requirements of 40
CFR 51.308(g) and (h), as explained in further detail in each
subsequent section.
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    \23\ Final action approved on February 12, 2018 (83 FR 5927).
    \24\ See the EPA's proposed approval on November 30, 2018 (83 FR
62204). We note that in the event this proposed rule is not
finalized, there is already FIP in place which addresses the
previously identified deficiencies. Thus, regardless of whether the
EPA finalizes the proposed approval of the Arkansas Regional Haze
SO2 and PM SIP revision, Arkansas will have an
implementation plan in place that fully addresses the regional haze
requirements for the first implementation period.
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A. Class I Areas

    Arkansas has two Class I areas within its borders that are
addressed in the progress report: Upper Buffalo and Caney Creek
Wilderness areas.\25\ Visibility impairment at Arkansas' two Class I
areas was tracked in units of deciviews,\26\ which is related to the
cumulative sum of visibility impairment from individual aerosol species
as measured by two monitors in the IMPROVE Network.
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    \25\ Upper Buffalo Wilderness area, located in Newton County,
Arkansas, is an oak-hickory forest with intermittent portions of
shortleaf pine located in the Ozark National Forest and offers
12,108 acres of boulder strewn and rugged scenery along the Buffalo
River. Caney Creek Wilderness is located in Polk County, Arkansas,
and covers 14,460 acres on the southern edge of the Ouachita
National Forest and protects a rugged portion of the Ouachita
Mountains.
    \26\ A deciview is a haze index derived from calculated light
extinction, such that uniform changes in haziness correspond to
uniform incremental changes in perception across the entire range of
conditions, from pristine to highly impaired. The preamble to the
Regional Haze Rule provides additional details about the deciview
(64 FR 35714, 35725, July 1, 1999).
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    Through collaboration with the Central Regional Air Planning
Association (CENRAP),\27\ ADEQ worked with the central states to assess
state-by-state contributions to visibility impairment in specific Class
I areas in Arkansas and those affected by emissions from Arkansas. ADEQ
used CENRAP as the main vehicle for developing its regional haze SIP
for the first implementation period. The results reported by ADEQ in
the progress report compared available monitored visibility conditions
to improvements that were projected based on the technical analysis and
emission inventories that were a part of the CENRAP modeling.\28\
CENRAP generated regional photochemical modeling results, visibility
projections, and source apportionment modeling to assist in identifying
contributions to visibility impairment at Caney Creek and Upper Buffalo
Wilderness Areas in Arkansas. ADEQ also indicated through CENRAP
modeling results that two Class I areas outside Arkansas' borders at
Hercules Glades and Mingo Wilderness areas in Missouri were impacted by
emissions from within Arkansas. In the ensuing sections, we discuss how
the State addressed the progress report requirements under 40 CFR
51.308(g) and (h) for these Class I areas, and we show our analysis and
proposed determination as to whether the State satisfied the
requirements.
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    \27\ The CENRAP is a collaborative effort of tribal governments,
state governments and various federal agencies representing the
central states (Texas, Oklahoma, Louisiana, Arkansas, Kansas,
Missouri, Nebraska, Iowa, Minnesota; and tribal governments included
in these states) that provided technical and policy tools for the
central states and tribes to comply with the EPA's Regional Haze
regulations. Due to lack of funding, CENRAP subsequently ceased to
function and Arkansas is communicating through the Central States
Air Resource Agencies (CenSARA) with the other states that were part
of CENRAP.
    \28\ See the technical support document (TSD) for CENRAP
Emissions and Air Quality Modeling to Support Regional Haze State
Implementation, found in Appendix 8.1 of the 2008 Arkansas Regional
Haze SIP. The TSD can be found in the docket for the proposal at
http://www.regulations.gov. The docket number is EPA-R06-OAR-2008-
0727.
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B. Status of Implementation of Measures

    The State evaluated the status of implementation of all measures in
its 2008 Arkansas Regional Haze SIP in accordance with the requirements
under 40 CFR 51.308(g).\29\ These measures were designed to address
sulfate, particulate organic matter, and nitrate, which are the three
largest contributors \30\ to visibility impairment at Upper Buffalo and
Caney Creek Wilderness areas. Ammonium sulfate is primarily from
SO2 precursor emissions from EGU point sources; \31\ nitrate
is primarily from mobile and point sources emissions; and particulate
organic matter is from area sources, particularly emissions from
fires.\32\ The major measures identified in the 2008 Arkansas Regional
Haze SIP to control

these pollutants and listed in the progress report are as follows:
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    \29\ The progress report was not required to include information
on the status of implementation of measures that became part of the
implementation plan after the submission of the progress report.
However, the EPA is including a discussion of measures from the
recent SIP submittals to complement the progress report and to
provide up-to-date information since the progress report's
submission in 2015. Concerning the aspects of the 2008 Arkansas
Regional Haze SIP that had been disapproved by the EPA in 2012
before the 2015 submission of the progress report, none involved new
SIP measures with compliance deadlines prior to the submission of
the progress report. Thus, our 2012 disapprovals do not necessarily
affect the progress report requirement regarding reporting on the
status of implementation of measures included in the implementation
plan.
    \30\ See Figures 2.1 and 2.2 from the 2015 regional haze
progress report (pages 16-17) which shows the 2007 to 2011 five-year
averages. The percent contributions of the major haze pollutant
contributors for Caney Creek and Upper Buffalo are as follows: (65%
and 56%) sulfate, (11% and 16%) nitrate, (15% and 18%) particulate
organic matter, 10% attributed to both sites for coarse mass, EC,
and soil.
    \31\ See Figure 2.3 of the progress report that shows Percent
Contribution by Source to SO2 Emissions in Arkansas for
2011: Non-EGU point sources account for 12 percent SO2
emissions, fires account for 8 percent, and approximately one
percent SO2 emissions are made up of area and mobile
sources (on- and off-road).
    \32\ See progress report SIP revision (page 16).

 BART Controls
 Clean Air Interstate Rule (CAIR) and CSAPR
 Source Retirement and Replacement Schedules
 Agriculture and Forestry Smoke Management
 Additional Federal Programs
1. BART Controls
    In the 2008 Arkansas Regional Haze SIP, the State determined that
there were eighteen facilities in Arkansas with BART-eligible
sources.33 34 The State chose to exempt those sources that
did not contribute to visibility impairment by performing a source-
specific screening analysis using CALPUFF modeling. After eliminating
BART-eligible sources whose modeled contributions to visibility
impairment were below the 0.5 dv threshold limit, nine boiler units
from six different facilities were found to be subject-to-BART \35\ and
are reflected in Table 2.2 of the progress report.\36\ In addition to
these subject-to-BART units determined by the State in the 2008
Arkansas Regional Haze SIP, the progress report also included
additional units from Georgia-Pacific Paper. As discussed in section
I.B of this proposed action, the BART portion of the 2008 Arkansas
Regional Haze SIP was partially approved and partially disapproved in
our 2012 final action.\37\ We approved Arkansas' identification of
BART-eligible sources from the 2008 Arkansas Regional Haze SIP with the
exception of Georgia-Pacific's 6A Boiler, which we found to be BART-
eligible, instead of being excluded as stated by the State in the 2008
Arkansas Regional Haze SIP. The EPA also approved the State's
identification of subject-to-BART sources, with the exception of the 6A
and 9A Boilers at Georgia-Pacific, which we found to be subject-to-BART
instead of exempt.\38\ Because of this, the progress report included
Georgia-Pacific's 6A and 9A Boilers as subject-to-BART at the time of
its submittal in 2015. However, despite the EPA's previous disapproval
of ADEQ's exemption finding, following the company's recent submission
of additional technical information and analyses, the EPA ultimately
agreed that Georgia Pacific's 6A and 9A Power Boilers are BART-
eligible, but are not subject-to-BART. ADEQ provided documentation
supporting this determination in Appendix A of the 2018 Arkansas
Regional Haze SO2 and PM SIP revision that the EPA proposed
for approval on November 30, 2018. Therefore, the State's most recent
identification of subject-to-BART units in the Arkansas Regional Haze
SO2 and PM SIP revision is the same as originally presented
in the 2008 Arkansas Regional Haze SIP (see Table 1):
---------------------------------------------------------------------------

    \33\ BART-eligible sources include certain categories of
existing major stationary sources built between August 7, 1962 and
August 7, 1977 and have potential emissions greater than 250 tons
per year (tpy). See 40 CFR 51 Appendix Y, II. How to Identify BART-
eligible Sources.
    \34\ See Table 9.1 of the 2008 Arkansas Regional Haze SIP (page
45).
    \35\ See Table 9.2 and Figure 9.2 of the 2008 Arkansas Regional
Haze SIP (page 48).
    \36\ See Arkansas Regional Haze Progress Report (page 20).
    \37\ See the final action at 77 FR 14604, March 12, 2012.
    \38\ See 77 FR 14606.

               Table 1--Subject-to-BART Units in Arkansas
------------------------------------------------------------------------
              Facility                              Unit ID
------------------------------------------------------------------------
SWEPCO Flint Creek Plant............  Unit 1 Boiler.
Arkansas Electric Cooperative         Unit 1 Boiler.
 Corporation--Bailey Generating
 Station.
Arkansas Electric Cooperative         Unit 1 Boiler.
 Corporation--John L. McClellan
 Generating Station.
Entergy Lake Catherine Plant........  Unit 4 Boiler.
Entergy White Bluff Plant...........  Unit 1 Boiler.
                                      Unit 2 Boiler.
                                      Auxiliary Boiler.
Domtar--Ashdown Mill................  No. 1 Power Boiler.
                                      No. 2 Power Boiler.
------------------------------------------------------------------------

    ADEQ was unable to determine at the time of the progress report's
submission when revisions to the 2012 disapproved portions of the SIP
would be submitted to the EPA. ADEQ was working then with facilities
and the EPA to develop the required five-factor analyses to address the
disapproved BART determinations. Consequently, updated BART
determinations and emission limits were not listed in the progress
report by the State because they were not yet available. The BART
determinations that were approved in 2012 were findings that the
existing limitations met the BART requirements. Therefore, as of the
submittal date of the progress report, there were not any new emission
reductions from subject-to-BART sources in Arkansas due to
implementation of BART limits more stringent than the existing limits.
Accordingly, there were no required efforts to implement new measures
on which the progress report was required to provide information. The
EPA approved the following BART determinations in 2012 for the 2008
Arkansas Regional Haze SIP: PM determination on SWEPCO Flint Creek
Plant Boiler No. 1; SO2 and PM determinations for the
natural gas firing scenario for Entergy Lake Catherine Plant Unit 4; PM
determinations for both bituminous and sub-bituminous coal firing
scenarios for Entergy White Bluff Plant Units 1 and 2; and PM
determination for Domtar Ashdown Mill Power Boiler No. 1.\39\
---------------------------------------------------------------------------

    \39\ See Tables 4 and 5 from the proposal at 40 CFR 64186,
64210-64211 (October 17, 2011).
---------------------------------------------------------------------------

    Subsequent to the June 2015 progress report submittal, the EPA
finalized a FIP in 2016 that established new BART emission limits for
the 2012 disapproved determinations.\40\ The FIP established
SO2, NOX, and PM emission limits under the BART
requirements for nine units at six facilities: SO2,
NOX, and PM BART for AECC Bailey Plant Unit 1 and the AECC
McClellan Plant Unit 1; SO2 and NOX BART for
SWEPCO Flint Creek Plant Boiler No. 1; NOX BART for the
natural gas firing scenario for Entergy Lake Catherine Plant Unit 4;
\41\ SO2 and NOX BART for

Entergy White Bluff Plant Units 1 and 2; SO2,
NOX, and PM BART for Entergy White Bluff Plant Auxiliary
Boiler; SO2 and NOX BART for Domtar Ashdown Mill
Power Boiler No. 1; and SO2, NOX and PM BART for
Domtar Ashdown Mill Power Boiler No. 2. The FIP also established
SO2 and NOX emission limits under the reasonable
progress requirements for Entergy Independence Units 1 and 2.
---------------------------------------------------------------------------

    \40\ See final action on September 27, 2016 (81 FR 66332) as
corrected on October 4, 2016 (81 FR 68319).
    \41\ The 2012 action had disapproved SO2,
NOX, and PM BART for the fuel oil firing scenario for the
Entergy Lake Catherine Plant Unit 4, but a FIP BART determination
was not established. Instead, Entergy committed to not burn fuel oil
at Lake Catherine Unit 4 until final EPA approval of BART for
SO2 and PM for the fuel oil firing scenario. This
commitment has now been made enforceable by the State through an
Administrative Order that has been adopted and incorporated in the
Arkansas Regional Haze SO2 and PM SIP revision.
---------------------------------------------------------------------------

    The State mentioned in the progress report that it was committed to
correcting the 2012 disapproved portions of the 2008 Arkansas Regional
Haze SIP. As described below and elsewhere, the State has made two
submissions to fulfill this commitment. Each SIP revision contained
updated BART determinations intended to replace the applicable FIP
established limits from 2016.
    First, on February 12, 2018, the EPA approved the 2017 Arkansas
Regional Haze NOX SIP revision.\42\ That submittal addressed
the NOX BART determinations established in the FIP for the
Arkansas subject-to-BART EGUs by replacing them with reliance upon the
CSAPR emissions trading program for O3 season NOX
as an alternative to source-specific NOX BART. The Arkansas
Regional Haze NOX SIP revision also established that no new
NOX emission controls were required beyond participation in
CSAPR for O3 season NOX for any source to achieve
reasonable progress for the first implementation period.
---------------------------------------------------------------------------

    \42\ See final action on February 12, 2018 for the Arkansas
Regional Haze NOX SIP revision (83 FR 5927).
---------------------------------------------------------------------------

    Second, on August 8, 2018, the State submitted the Arkansas
Regional Haze SO2 and PM SIP revision. That submittal
addressed all remaining disapproved parts of the 2008 Arkansas Regional
Haze SIP, with exception of the BART and associated long-term strategy
requirements for the Domtar Ashdown Mill Power Boilers No. 1 and 2. The
majority of the BART determinations in that SIP revision were
essentially identical to the BART determinations in the FIP except for
different BART requirements for White Bluff units 1 and 2.\43\ The
submittal established that each White Bluff unit was to comply with an
updated SO2 BART emission limit of 0.60 lb/MMBtu. That is
based on the use of low sulfur coal and an enforceable commitment to
cease coal combustion by the end of 2028. The submittal also
established a new NOX emission limit of 32.2 pounds per hour
(pph) to satisfy NOX BART for White Bluff's auxiliary
boiler, replacing the determination in the Arkansas Regional
NOX SIP revision (relying upon CSAPR to satisfy
NOX BART) that we previously approved. The State made all of
these BART determinations enforceable through administrative
orders.\44\ The State determined that no additional SO2 or
PM controls beyond BART were necessary for reasonable progress during
the first planning period.\45\ The EPA proposed to approve a large
portion of the SIP revision on November 30, 2018.\46\
---------------------------------------------------------------------------

    \43\ For the White Bluff units, the FIP required an
SO2 emission limit of 0.06 lb/MMBtu with a five-year
compliance date, based on the installation of dry scrubbers. The
Arkansas Regional Haze SO2 and PM SIP revision does not
require the SO2 emission limit of 0.06 lb/MMBtu, but it
does require that Entergy move forward with its announced plans to
cease coal combustion at the White Bluff Units by 2028 and to meet
an SO2 emission limit of 0.60 lb/MMBtu in the interim.
Once the units cease coal combustion, SO2 emissions are
expected to significantly decrease.
    \44\ The Administrative Orders can be found in the Arkansas
Regional Haze SO2 and PM BART SIP Revision.
    \45\ In the Arkansas Regional Haze SO2 and PM SIP
revision, part of ADEQ's basis for determining the sources to
further evaluate under the four reasonable progress factors was
analyses and determinations for whether sources were subject-to-BART
in the first implementation period. For the Domtar facility in
particular, the State relied on the fact that a FIP is in place to
address the BART requirements. In our November 30, 2018 proposed
approval (83 FR 62204), we proposed to agree that this is an
appropriate basis on which we find that nothing further is needed
for reasonable progress at this source. If ADEQ chooses to submit a
future SIP revision to address BART requirements for Domtar Power
Boilers No. 1 and No. 2, we will evaluate the SIP submittal at that
time and also whether it addresses reasonable progress requirements.
    \46\ See proposed action on November 30, 2018 for the Arkansas
Regional Haze SO2 and PM SIP revision (83 FR 62204). Note
that the SIP revision also addressed separate CAA requirements
related to interstate visibility transport under CAA section
110(a)(2)(D)(i)(II), but we did not propose action on that part of
the submittal.
---------------------------------------------------------------------------

    The Arkansas Regional Haze NOX SIP revision,\47\ the
Arkansas Regional Haze SO2 and PM SIP revision (if EPA's
proposed approval is finalized),\48\ and the remaining part of the FIP
that addresses the BART and associated long-term strategy requirements
for Domtar together fully address the deficiencies of the 2008 Arkansas
Regional Haze SIP previously identified in 2012 by the EPA. The EPA is
collectively providing all of these updated BART determination emission
limits in Table 2 below since they were not all available at the time
of the progress report's submission.
---------------------------------------------------------------------------

    \47\ Final action approved on February 12, 2018 for the Arkansas
Regional Haze NOX SIP revision (83 FR 5927).
    \48\ In the event that this proposed rule is not finalized, we
note that there is already a FIP in place which addresses the
previously identified deficiencies.

                                      Table 2--Updated BART Determinations
----------------------------------------------------------------------------------------------------------------
                                                                             BART emission limit
           Facility                        Unit            -----------------------------------------------------
                                                                   SO2               NOX              PM10
----------------------------------------------------------------------------------------------------------------
SWEPCO Flint Creek Plant......  Unit 1 Boiler.............  0.06 lb/MMBtu**.  Reliance on       0.1 lb/MMBtu.*
Arkansas Electric Cooperative   Unit 1 Boiler.............  Use fuel with      Participation    Use fuel with
 Corporation--Bailey            ..........................   sulfur limit of   in CSAPR          sulfur limit of
 Generating Station.            ..........................   0.5% by weight    Trading Program   0.5% by
Arkansas Electric Cooperative   Unit 1 Boiler.............   **.               for O3 season     weight.**
 Corporation--John L.                                       ................   NOX to satisfy   ................
 McClellan Generating Station.                              Use fuel with      NOX BART a.      Use fuel with
                                                             sulfur limit of                     sulfur limit of
                                                             0.5% by weight                      0.5% by
                                                             **.                                 weight.**
Entergy--Lake Catherine.......  Unit 4 Boiler b...........  (Natural gas                        (Natural gas
                                                             firing                              firing
                                                             scenario) Burn                      scenario) 45
                                                             natural gas                         pph and burn
                                                             only*.                              natural gas
                                                                                only.*
Entergy--White Bluff..........  Unit 1 Boiler.............  0.60 lb/MMBtu                       0.1 lb/MMBtu.*
                                                             [dagger].
                                Unit 2 Boiler.............  0.60 lb/                            0.1 lb/MMBtu.*
                                                             MMBtu[dagger].
                                Auxiliary Boiler..........  105.2 pph**.....  32.2 pph***.....  4.5 pph.**
Domtar--Ashdown Mill..........  No. 1 Power Boiler........  504 ppd [Dagger]  207.4 pph         0.07 lb/MMBtu.*
                                                                               [Dagger].

                                No. 2 Power Boiler........  91.5 pph          345 pp h[Dagger]  PM standard
                                                             [Dagger].                           under 40 CFR
                                                                                part 63,
                                                                                subpart DDDDD
                                                                                as
                                                                                revised.[Dagger
                                                                                ]
----------------------------------------------------------------------------------------------------------------
* The EPA approved this BART limit in the March 12, 2012 final action (77 FR 14604).
** This BART limit established in the FIP will be replaced with the State's own identical limit pending final
  approval of the August 8, 2018 Arkansas Regional Haze SO2 and PM SIP revision. See the EPA's proposed approval
  on November 30, 2018 (83 FR 62204).
*** Note that we previously withdrew the 32.2 pph NOX limit from the FIP and approved Arkansas' reliance upon
  CSAPR to satisfy NOX BART (83 FR 5927). However, ADEQ's identification of the Auxiliary Boiler as
  participating in CSAPR for O3 season NOX was in error. Therefore, we proposed to withdraw our prior approved
  determination of the State's reliance upon CSAPR and replace it with 32.2 pph NOX to satisfy NOX BART for the
  auxiliary boiler in our proposed approval of the Arkansas Regional Haze SO2 and PM SIP revision. See the EPA's
  proposed approval of the Arkansas Regional Haze SO2 and PM SIP revision on November 30, 2018 (83 FR 62204).
[dagger] This is a new revised BART limit proposed in the August 8, 2018 Arkansas Regional Haze SO2 and PM SIP
  revision. See the EPA's proposed approval on November 30, 2018 (83 FR 62204).
[Dagger] The EPA established this FIP BART limit on September 27, 2016. See final action (81 FR 66332) as
  corrected on October 4, 2016 (81 FR 68319).
a The EPA approved this BART alternative in the February 12, 2018 Arkansas Regional Haze NOX SIP Revision final
  action (83 FR 5927).
b There is an enforceable ban (not a current BART Determination) by the State on burning fuel oil for Lake
  Catherine's unit 4 boiler until the EPA approves a SIP revision with BART determinations for the fuel oil
  firing scenario.

2. Reasonable Progress Source Controls
    In the Arkansas Regional Haze NOX SIP revision and the
Arkansas Regional Haze SO2 and PM SIP revision, ADEQ
evaluated the need for additional source controls under the reasonable
progress requirements. In determining reasonable progress, CAA section
169(A)(g)(1) requires states to examine the cost of compliance, the
time necessary for compliance, energy and non-air quality environmental
impacts, and remaining useful life. In the Arkansas Regional Haze
NOX SIP revision, the State determined that no additional
NOX controls beyond participation in CSAPR for O3
season NOX were necessary to satisfy the reasonable progress
requirement with respect to NOX for the first implementation
period.\49\ As discussed in Section II of our proposed action on the
Arkansas Regional Haze SO2 and PM SIP revision, ADEQ
determined that no additional SO2 and PM controls at
Independence Units 1 and 2 or any other Arkansas sources are necessary
under reasonable progress for the first implementation period.\50\
---------------------------------------------------------------------------

    \49\ The EPA approved this in the February 12, 2018 Arkansas
Regional Haze NOX SIP Revision final action (83 FR 5927).
    \50\ See the EPA's proposed approval of the Arkansas Regional
Haze SO2 and PM SIP revision on November 30, 2018 (83 FR
62204).
---------------------------------------------------------------------------

3. CAIR and CSAPR
    In 2005, the EPA issued CAIR,\51\ which participating states could
rely on in lieu of BART for EGUs.\52\ CAIR was designed to address
power plant pollution transported from one state to another via a cap-
and-trade system to reduce SO2 and NOX emissions
as the target pollutants.\53\ In December 2008, the D.C. Circuit
remanded CAIR to the EPA, leaving existing CAIR programs in place while
directing the EPA to replace them with a new rule.\54\ Although CAIR
was remanded, CAIR remained in effect at the time of the progress
report's development and sources in Arkansas continued to comply with
the state and federal requirements associated with CAIR. CAIR consisted
of two phases of reductions for NOX and SO2.
Phase I ran from 2009 to 2014 and Arkansas' NOX budget
amounted to 11,514 tons NOX per annual O3 season.
Phase II begun in 2015 and was set to continue indefinitely with
Arkansas' NOX budget set at 9,116 tons NOX per
annual O3 season. Table 2.3 of the progress report shows the
NOX O3 season allocations distributed among the
different Arkansas sources for the 2009 to 2017 time-period.
---------------------------------------------------------------------------

    \51\ See 70 FR 25161 (May 12, 2005).
    \52\ See 70 FR 39104, 39139 (July 6, 2005).
    \53\ Although Arkansas was subject to certain NOX
requirements of CAIR, including the statewide O3 season
NOX budget, it elected not to rely on CAIR in its 2008
Arkansas Regional Haze SIP to satisfy the NOX BART
requirement for its EGUs. Note that it would have been sufficient
for Arkansas to rely on CAIR to satisfy NOX BART.
    \54\ North Carolina v. EPA, 531 F.3d 896, 901 (D.C. Cir. 2008),
modified, 550 F.3d 1176, 1178 (D.C. Cir. 2008).
---------------------------------------------------------------------------

    In 2011, the EPA finalized CSAPR to replace CAIR.\55\ In 2012, the
EPA published a final rule allowing states that participate in the
CSAPR trading program to rely on CSAPR to satisfy BART for EGUs,\56\
including states participating only for O3 season
NOX.\57\ CSAPR requires 28 eastern states to reduce power
plant emissions that contribute to O3 and PM2.5
pollution in other states. The rule requires reductions in
O3 season NOX emissions that cross state lines
for certain states under the O3 requirements, and reductions
in annual SO2 and NOX emissions for certain
states under the PM2.5 requirements. The EPA set emission
budgets for each state covered by CSAPR. Allowances are allocated to
affected sources based on these state emission budgets.\58\
---------------------------------------------------------------------------

    \55\ See 76 FR 48207 (August 8, 2011).
    \56\ See 77 FR 33642 (June 7, 2012).
    \57\ Arkansas EGUs are covered under CSAPR for O3
season NOX. See 76 FR 82219 (December 30, 2011).
    \58\ The rule provides flexibility to affected sources, allowing
sources in each state to determine their own compliance path. This
includes adding or operating control technologies, upgrading or
improving controls, switching fuels, and using allowances. Sources
can buy and sell allowances and bank (save) allowances for future
use as long as each source holds enough allowances to account for
its emissions by the end of the compliance period.
---------------------------------------------------------------------------

    Since promulgating the use of CSAPR as an alternative to source-
specific BART for EGUs, the EPA has promulgated an update to the CSAPR
program with more stringent budgets.\59\ The CSAPR update revised the
O3 season NOX budget for Arkansas EGUs from
15,110 tons NOX in 2015 to 12,048 tons NOX
(10,132 tons NOX allocated to existing EGUs) in 2017 with a
further reduction to 9,210 tons NOX (7,781 tons
NOX allocated to existing EGUs) in 2018 and beyond.\60\
Participation in CSAPR

for O3 season NOX is federally enforceable under
40 CFR 52.38.
---------------------------------------------------------------------------

    \59\ See 81 FR 74504. On October 26, 2016, we finalized an
update to CSAPR that addresses the 1997 O3 NAAQS portion
of the remand as well as the CAA requirements addressing interstate
transport for the 2008 O3 NAAQS.
    \60\ CSAPR has been subject to extensive litigation, and on July
28, 2015, the D.C. Circuit issued a decision generally upholding
CSAPR but remanding without vacating the CSAPR emissions budgets for
a number of states. Arkansas' O3 season NOX
budgets were not included in the remand. EME Homer City Generation
v. EPA, 795 F.3d 118, 138 (D.C. Cir. 2015).
---------------------------------------------------------------------------

    On February 12, 2018, we approved the Arkansas Regional Haze
NOX SIP revision (effective March 14, 2018) which replaced
all source-specific NOX BART determinations for EGUs
established in the FIP with reliance upon the CSAPR emissions trading
program for O3 season NOX as an alternative to
NOX BART.\61\ The O3 season NOX
requirements under CSAPR apply to all subject-to-BART units in Table 1
of this proposed action except the Domtar No. 1 and 2 Power Boilers,
and the White Bluff Auxiliary Boiler. The Arkansas Regional Haze
NOX SIP revision addressed the NOX BART
requirements for Bailey Unit 1, McClellan Unit 1, Flint Creek Boiler
No. 1, Lake Catherine Unit 4; White Bluff Units 1 and 2, and the
Auxiliary Boiler. In that SIP submittal, ADEQ erroneously identified
White Bluff's Auxiliary Boiler as participating in CSAPR for
O3 season NOX and elected to rely on
participation in that trading program to satisfy the Auxiliary Boiler's
NOX BART requirements. Although we approved the SIP
submittal on February 12, 2018,\62\ our approval of the State's
reliance on CSAPR for O3 season NOX to satisfy
the BART requirements for the Auxiliary Boiler was made in error.
Therefore, we proposed to withdraw our approval of the State's reliance
upon CSAPR for the Auxiliary Boiler and replace it with our approval of
a source-specific 32.2 pph NOX BART emission limit related
to the Arkansas Regional Haze SO2 and PM SIP submitted on
November 30, 2018.\63\
---------------------------------------------------------------------------

    \61\ See 82 FR 42627 (September 11, 2017) for the proposed
approval. See also 83 FR 5927 and 83 FR 5915 (February 12, 2018) for
the final action.
    \62\ See 83 FR 5927 (February 12, 2018).
    \63\ See the EPA's proposed approval on November 30, 2018 (83 FR
62204).
---------------------------------------------------------------------------

4. Source Retirement and Replacement Schedules
    In accordance with Subchapter <IP_ADDRESS> of the 2008 Arkansas
Regional Haze SIP, ADEQ tracked source retirement and replacement
through ongoing point source inventories.64 65 The progress
report showed that ADEQ has performed this tracking. Five new permitted
Prevention of Significant Deterioration (PSD) facilities were
inventoried and the new corresponding total potential-to-emit (PTE)
emissions for NOX and SO2 were reported at 5,833
tpy and 7,374 tpy. The total actual NOX and SO2
emissions,\66\ however, were reported lower at 1,741 tpy and 3,303 tpy,
respectively. In addition, sixteen PSD facilities have shut down since
2008, resulting in a total reduction of 15,893 tpy in permitted
NOX emissions and a total reduction of 1,126 tpy in
permitted SO2 emissions.\67\
---------------------------------------------------------------------------

    \64\ 40 CFR 51.308(d)(3)(v)(D) requires the State of Arkansas to
consider source retirement and replacement schedules in developing
RPGs.
    \65\ 40 CFR 51.308(d)(3)(v)(B) requires the State of Arkansas to
consider measures to mitigate the impacts of construction
activities.
    \66\ As reported by the facilities in their Annual Emissions
Inventory Report for 2012.
    \67\ See Tables 2.4 through 2.6 of the progress report.
---------------------------------------------------------------------------

5. Agriculture and Forestry Smoke Management \68\
---------------------------------------------------------------------------

    \68\ 40 CFR 51.308(d)(3)(v)(E) requires Arkansas to consider
smoke management techniques for the purposes of agricultural and
forestry management.
---------------------------------------------------------------------------

    The progress report mentioned that the State is currently relying
on a Smoke Management Plan (SMP) in its 2008 Arkansas Regional Haze SIP
that the Arkansas Forestry Commission approved in 2007. Arkansas' SMP
was designed to assure that prescribed fires are planned and executed
in a manner designed to minimize the impacts from smoke produced by
prescribed fires. The programs in this measure are generally designed
to limit increases in emissions, rather than to reduce existing
emissions.\69\
---------------------------------------------------------------------------

    \69\ Documentation of this SMP program is in Appendix 11.1 of
the 2008 Arkansas Regional Haze SIP or a copy may be found at http://forestry.arkansas.gov/Services/KidsTeachersEveryone/Documents/ArkansasVSMG.pdf.
---------------------------------------------------------------------------

6. Additional Federal Programs \70\
---------------------------------------------------------------------------

    \70\ 40 CFR 51.308(d)(3)(v)(A) requires the State of Arkansas to
consider emission reductions from ongoing pollution control programs
in the development of its long-term strategy.
---------------------------------------------------------------------------

    The State of Arkansas also considered in its progress report the
following ongoing pollution control programs in the 2008 Arkansas
Regional Haze SIP as controls used for continuing emission reductions:
     Mercury and Air Toxics Standard (MATS).\71\
---------------------------------------------------------------------------

    \71\ See 77 FR 9304 (February 16, 2012). Arkansas anticipated
that reductions in SO2 emissions from the State's coal-
fired EGUs would occur as a result of the MATS rule. This rule
allowed for the installation of pollution control equipment to meet
requirements under 40 CFR part 63, subpart UUUUU--National Emission
Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric
Utility Steam Generating Units. At the time the progress report was
submitted, Flint Creek planned to install a particular type of dry
scrubber that controls SO2 and other acid gases called
Novel Integrated Deacidification (NID) technology and Activated
Carbon Injection (ACI) to comply with MATS. Since that time, Flint
Creek did install the NID system on boiler unit 1. Because the
scrubber system also meets the qualifications as being a BART
control, the State is complying with the more stringent
SO2 BART requirements included in the FIP and is meeting
both rules using the same controls. The SO2 BART emission
rate, therefore, was set at 0.06 lb/MMBtu based on the installation
and operation of the NID technology.
---------------------------------------------------------------------------

     Tier 2 Vehicle Emission standards.\72\
---------------------------------------------------------------------------

    \72\ EPA's Tier 2 fleet averaging program for on-road vehicles,
modeled after the California LEV (Low Emissions Vehicle) II
standards, became effective in the 2005 model year. The mix of
vehicles a manufacturer sells each year must have average
NOX emissions below a specified value.
---------------------------------------------------------------------------

     Heavy-Duty Highway Rule.\73\
---------------------------------------------------------------------------

    \73\ The Heavy-Duty Highway Rule was adopted on January 18,
2001, by EPA with the objective of reducing emissions from diesel
engines by setting a PM emission standard for new heavy-duty
engines, which took effect with the 2007 model year. The rule also
required reduction of sulfur in diesel fuel to facilitate the use of
modern pollution control technology on these engines.
---------------------------------------------------------------------------

     Highway Diesel and Non-Road Diesel Rules.\74\
---------------------------------------------------------------------------

    \74\ These rules were initially effective in 2004 and were fully
phased in by 2012. The non-road diesel rule set standards that
reduced emissions by more than 90 percent from non-road diesel
equipment and, beginning in 2007, the rule reduced fuel sulfur
levels by 99 percent from previous levels. The reduction in fuel
sulfur levels applied to most non-road diesel fuel in 2010 and
applied to fuel used in locomotives and marine vessels in 2012.
---------------------------------------------------------------------------

     Ultra-Low Sulfur Diesel Rule.\75\
---------------------------------------------------------------------------

    \75\ The Ultra-Low Sulfur Diesel Rule resulted in better PM
control from diesel engines. The EPA regulations required that at
least 80 percent of highway diesel fuel in the United States be
ULSD, and by 2010, all highway diesel fuel became ULSD. The EPA also
required a major reduction in the sulfur content of diesel fuel
intended for use in locomotive, marine, and non-road engines and
equipment including construction, agricultural, industrial, and
airport equipment.
---------------------------------------------------------------------------

     Maximum Achievable Control Technology (MACT).\76\
---------------------------------------------------------------------------

    \76\ The MACT standards are part of the National Emission
Standards for Hazardous Air Pollutants (NESHAP), provided under 40
CFR part 63. See 76 FR 64186, 64198 and 70 FR 39162. CENRAP modeling
demonstrated that VOCs from anthropogenic sources are not
significant visibility-impairing pollutants at Caney Creek and Upper
Buffalo.
---------------------------------------------------------------------------

7. EPA's Conclusion on the Status of Implementation of Measures
    The EPA proposes to find that the State has adequately addressed
the applicable provisions under 40 CFR 51.308(g) regarding reporting
the status of implementation of measures in its implementation plan.
The State's progress report documented the status of all measures
included in its regional haze SIP (as of the submission of the progress
report) and it also described additional measures that came into effect
since the State's 2008 regional haze SIP was completed, including state
regulations and various federal measures. All major control measures
were identified and the strategy behind each control was explained. The
State included a summary of the implementation status associated with
each measure and quantified the benefits where possible. In addition,
the progress report SIP adequately outlined the compliance timeframe
for all controls.

C. Emission Reductions From Implementation of Measures

    The State presented emission data in its progress report that
provided a summary of the emission trends and reductions achieved in
the state through the implementation of the measures in the SIP. The
State identified ammonium sulfate, particulate organic matter, and
nitrate as the three largest pollutant contributors to visibility
impairment caused by regional haze at Arkansas' Class I areas for the
first implementation period.\77\ The progress report indicated that the
primary cause of ammonium sulfate, the most significant haze
contributor in Arkansas, is SO2 precursor emissions. In
2011, point sources contributed to 90 percent of the overall
SO2 emissions in Arkansas with EGUs responsible for 78
percent of the total SO2 emissions.\78\ For this reason, the
State focused on reporting emission reductions from EGU point sources
in the progress report as an effective method of improving visibility
in Arkansas.
---------------------------------------------------------------------------

    \77\ See Figures 2.1 and 2.2 from the 2015 regional haze
progress report (page 17). The percent contributions (2007-2011) of
the major haze pollutant contributors for Caney Creek and Upper
Buffalo are as follows: (65% and 56%) sulfate, (11% and 16%)
nitrate, (15% and 18%) particulate organic matter, 10% attributed to
both sites for coarse mass, EC, and soil.
    \78\ See the Arkansas progress report (page 18).
---------------------------------------------------------------------------

    The State reported EGU point source emission data from Arkansas for
NOX and SO2 for the 2000 to 2011 time-period.\79\
There were not any emission reductions from subject-to-BART sources in
Arkansas due to implementation of BART limits when the progress report
was submitted. Nevertheless, the overall EGU emissions trended downward
from the baseline for NOX, with a slight uptick in 2011 for
SO2 emissions. Arkansas noted that as of 2011, EGU emissions
increased by 2,885 tpy for SO2 and decreased by 3,741 tpy
for NOX from the 2002 baseline. During the 2002 to 2011
time-span, on a heat input basis, both NOX and
SO2 EGU emission rates (lb/MMBtu) decreased. This indicates
that the overall average control efficiencies improved and the slight
SO2 emissions uptick was a result of increased EGU
activity.\80\
---------------------------------------------------------------------------

    \79\ See Table 3.1 in the Arkansas progress report (page 35).
    \80\ See Figure 3.2 in the Arkansas progress report (page 38).
---------------------------------------------------------------------------

    Table 3 below, provided by the EPA to complement the State's
report, compares more recent emission trends going past 2011.\81\ It
compares the 2002 to 2011 annual EGU emission trends provided by the
State in the progress report to more recent annual EGU emission data
provided by the EPA from 2012 to 2017.\82\ Table 3 shows that
NOX and SO2 EGU point source emissions have
decreased during the 2011 to 2017 time-period. Comparing 2011 emissions
to the 2018 projected emissions developed for the 2008 SIP, the State
projected annual SO2 emissions to increase by an additional
125 tpy and annual NOX emissions to decrease by an
additional 10,167 tpy in 2018 from 2011 observed emissions.\83\ The
more recent emission data, however, shows a large decrease in
SO2 emissions from EGUs. Specifically, from 2014 to 2015,
there was a 30,354 tpy decrease in SO2 emissions and a
14,783 tpy decrease in NOX emissions. This corresponds to a
decline in EGU activity as noted by the decrease in heat input in 2015.
EGU activity has since increased from 2015 to 2017, but the emissions
remain well below 2014 emission levels. Overall, from the 2002 to 2017,
SO2 emissions from EGUs have reduced by 22,969 tpy
(increased 2,885 tpy from 2002 to 2011, then decreased 25,854 tpy from
2011 to 2017) and NOX emissions have reduced by 14,579 tpy
(decreased 3,741 tpy from 2002 to 2011, then decreased an additional
10,838 tpy from 2011 to 2017). The State's progress report mentioned
that further significant emission reductions would be realized from a
final permit that was issued on August 25, 2013, at Flint Creek for the
installation and operation of control equipment to significantly reduce
SO2 emissions.\84\
---------------------------------------------------------------------------

    \81\ Source: U.S. EPA Clean Air Market Division www.epa.gov/airmarkt/.
    \82\ Source: U.S. EPA Clean Air Market Division www.epa.gov/airmarkt/.
    \83\ See Page 37 of the progress report.
    \84\ See ADEQ Air Permit No. 027-AOP-R6 (AFIN 04-00107). This
permit allowed for the installation of pollution control equipment
under the MATS rule with an SO2 emission limit of 0.2 lb/
MMBtu, and a compliance date of April 16, 2016. Since the issuance
of that permit, ADEQ has submitted the Arkansas Regional Haze
SO2 and PM SIP revision, which establishes an
SO2 BART emission limit of 0.06 lb/MMBtu, achievable by
the equipment installed to meet MATS. The SIP revision requires
compliance with the 0.06 lb/MMBtu SO2 emission limit by
``the effective date of the Administrative Order,'' which requires
compliance by August 7, 2018.

                                        Table 3--Annual NOX and SO2 Emissions From EGU Point Sources in Arkansas
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Heat input    NOX emission rate  SO2 emission rate
                               Year                                    NOX (tpy)       SO2 (tpy)        (MMBtu)         (lb/MMBtu)         (lb/MMBtu)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2002..............................................................          42,079          70,738     303,031,688              0.278              0.467
2005..............................................................          35,333          66,190     305,909,694              0.231              0.433
2008..............................................................          37,800          73,289     339,622,527              0.223              0.432
2011..............................................................          38,338          73,623     411,725,177              0.186              0.358
2012 *............................................................          34,847          76,326     440,336,753              0.158              0.347
2013 *............................................................          37,148          73,578     427,915,347              0.174              0.344
2014 *............................................................          38,396          75,898     410,742,039              0.187              0.370
2015 *............................................................          23,613          45,544     337,259,867              0.140              0.270
2016 *............................................................          26,892          46,573     382,621,452              0.141              0.243
2017 *............................................................          27,500          47,769     391,814,298              0.140              0.244
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Provided by the EPA from the EIS Gateway database.

    Table 4, provided by the EPA, compares National Emissions Inventory
(NEI) data for total point sources from 2002 to 2014. This complements
the categorized NEI point source data (EGU and non-EGU) inventoried by
the State in the progress report from 2002 to 2011. It also provides
reported emissions data from more current NEI versions than available
when the progress report was submitted in 2015.\85\ Table 4 shows that
fine particle and coarse mass PM emission reductions are considerably
lower than their NEI 2002 totals when compared to more recent NEI
data.\86\ PM10 point source emissions decreased by 6,427 tpy
(39%) and PM2.5 point source emissions decreased by

5,600 tpy (49%) for the 2002 to 2014 period. NOX emissions
stayed relatively steady at 71,000 tpy and SO2 emissions
decreased slightly by 4.6 percent for the 2002 to 2014 period. Although
the reductions in SO2 and NOX emissions are not
especially pronounced for that time-period, the total point source
emission trends are consistent with what is shown in Table 3 for EGU
point sources from 2002 to 2014. We anticipate that the total NEI point
source data going forward after 2014 will reflect the substantial
decreases in PM, SO2, and NOX emissions as
already displayed in the EGU point source reductions reported by CAMD
data in Table 3.
---------------------------------------------------------------------------

    \85\ The State noted that NEI emissions data for 2011 in the
progress report was obtained from 2011 NEI version 1.
    \86\ As reported in the online EPA Emissions Inventory System
(EIS) Gateway database for point sources only.

                    Table 4--NEI Total Point Source Emission Data for Arkansas for 2002-2014
----------------------------------------------------------------------------------------------------------------
                                                                                PM2.5 (tpy)
                      Year                           NOX (tpy)       SO2 (tpy)      PM10 (tpy)
----------------------------------------------------------------------------------------------------------------
2002............................................          70,726          89,870          16,318          11,536
2005............................................          59,431          75,483           8,532           6,105
2008............................................          75,045          87,308          11,060           7,671
2011............................................          71,402          84,922          10,451           6,782
2014............................................          71,588          85,714           9,891           5,936
----------------------------------------------------------------------------------------------------------------

    In addition to the above reductions, there will also be some
additional future reductions due to more stringent CSAPR allocations
and BART requirements implemented from the recent Arkansas Regional
Haze SO2 and PM SIP revision. The CSAPR update revised the
O3 season NOX budget for Arkansas units from
15,110 tons NOX in 2015 to 12,048 tons NOX
(10,132 tons NOX allocated to existing EGUs) in 2017 with a
further reduction to 9,210 tons NOX (7,781 tons
NOX allocated to existing EGUs) in 2018 and beyond. The 2017
actual O3 season EGU emissions for Arkansas totaled 12,811
tons NOX. Some EGUs chose to install combustion controls to
comply with CSAPR that would reduce emissions year-round, not just in
the O3 season. This includes the installation of low
NOX burners at the White Bluff and Independence facilities.
The 2018 actual O3 season EGU emissions for Arkansas totaled
10,952 tons NOX.\87\
---------------------------------------------------------------------------

    \87\ Source: U.S. EPA Clean Air Market Division www.epa.gov/airmarkt/.
---------------------------------------------------------------------------

    The State noted that, along with the replacement of CAIR with
CSAPR, there have been many changes to the ongoing air pollution
programs since EPA's partial approval of Arkansas' regional haze SIP in
2012. These changes included more stringent emission standards,
renewable fuel standards, fuel efficiency standards, marine and
aircraft standards, mercury and air toxics standards, and various
national emission standards for hazardous air pollution. Arkansas noted
that these more recent air pollution programs are anticipated to result
in even greater emission reductions that could result in further
visibility improvement than the programs in place at the time the 2008
Arkansas Regional Haze SIP revision was submitted to the EPA.
    Lastly, recent and planned retirements of various plants may result
in further visibility improvement at Arkansas Class I areas. In the
Arkansas Regional Haze SO2 and PM SIP revision, ADEQ noted
the planned retirement of Lake Catherine by the end of 2028 and
Entergy's plans to cease coal combustion at the Independence facility
by the end of 2030. ADEQ also noted that there have been recent changes
in operations at large point sources that have historically impacted
Arkansas Class I areas, including the recent retirement of the Big
Brown Plant, Sandow Plant, Monticello Plant, and the Deely Plant in
Texas. The coal-fired units at the Tennessee Valley Authority Allen
Plant, located in Memphis, Tennessee, were also scheduled to retire by
June 2018 and be replaced with natural gas generators.
    The EPA proposes to conclude that the State has adequately
addressed the applicable provisions under 40 CFR 51.308(g) regarding a
summary of emission reductions achieved for visibility impairing
pollutants. Overall, the State demonstrated the emission reductions
achieved for the major contributing visibility impairing pollutants in
the State for the first implementation period. Emissions of
SO2, NOX, and PM, the main contributors to
regional haze in Class I areas potentially affected by emissions from
Arkansas, have all been decreasing. As demonstrated by the more recent
available data, the SO2 and NOX haze pollutant
precursors from EGU point sources in the state have decreased from the
baseline levels in 2002, especially since 2015. Also, the trend for
fine particles and coarse mass emissions, pollutants that directly
create haze, have been decreasing since 2002. Overall visibility
conditions are improving as a result of these reductions together with
decreases from outside of the state. With the implementation of the new
BART controls and more stringent NOX allocations under
CSAPR, further emission reductions should be realized and visibility
impairment at affected Class I areas should continue to improve.

D. Visibility Conditions and Changes

    Arkansas included in its progress report the annual average
visibility from 2001 to 2011 for the twenty percent best (least
impaired) and twenty percent worst (most impaired) days at Caney Creek
and Upper Buffalo Wilderness areas.\88\ Although visibility conditions
have varied from year-to-year, the progress report showed that both
Caney Creek and Upper Buffalo have displayed an overall improvement in
visibility since 2001.\89\ Arkansas reported that both areas showed
improved visibility from the 2000 to 2004 baseline during the worst
days for the most current period (2007 to 2011) and for the period
previous to the most current (2005 to 2009) available at the time of
the progress report's development.\90\ Both class I areas similarly are
showing improvement from the baseline on the twenty percent best days
and satisfy the goal of no visibility degradation for the first
implementation period. Table 5 shows that the visibilities at Caney
Creek and Upper Buffalo during the 2007 to 2011 period were 0.96 dv and
0.67 dv below the baseline for the twenty percent best days.
---------------------------------------------------------------------------

    \88\ The most and least impaired days in the regional haze rule
refers to the average visibility impairment (measured in dv) for the
twenty percent of monitored days in a calendar year with the highest
and lowest amount of visibility impairment, respectively, averaged
over a five-year period (see 40 CFR 51.301). In this report, when we
refer to ``best days'' we mean ``least impaired'' and when we refer
to ``worst days'' we mean ``most impaired.''
    \89\ See Figures 4.1 to 4.2 and Tables 4.1 to 4.2 of the
progress report (pages 41-43).
    \90\ Progress reports for the first implementation period used
specific terms to describe time-periods. ``Baseline visibility
conditions'' refers to conditions during the 2000 to 2004 time-
period. ``Current visibility conditions'' refers to the most recent
five-year average data available at the time the State submitted its
progress report for public review. ``Past five years'' refers to the
five-year average previous to the five years used for ``current
visibility conditions.''

                 Table 5--Visibility at Arkansas Class I Areas for the Twenty Percent Best Days
                                               [Five-Year Average]
----------------------------------------------------------------------------------------------------------------
                                                  Baseline (2000-                                   Most recent
                  Class I area                      2004) (dv)      (2005-2009)     (2007-2011)   minus baseline
                                                                       (dv)            (dv)            (dv)
----------------------------------------------------------------------------------------------------------------
Caney Creek Wilderness..........................           11.39           11.06           10.43           -0.96
Upper Buffalo Wilderness........................           11.71           11.85           11.04           -0.67
----------------------------------------------------------------------------------------------------------------
* A negative sign indicates a reduction from the baseline.

    In the State's August 8, 2018 submittal (Arkansas Regional Haze
SO2 and PM SIP), the State's 2018 RPGs from the 2008
Arkansas Regional Haze SIP for Caney Creek and Upper Buffalo were
revised downward to 22.47 dv and 22.51 dv for the twenty percent worst
days.\91\ These revised RPGs are more stringent than what was
established in the 2008 Arkansas Regional Haze SIP and account for the
controls required in the Arkansas Regional Haze SO2 and PM
SIP submittal.\92\ We proposed to agree with the State's newly revised
2018 RPGs for the twenty percent worst days in our November 30, 2018
proposed approval action.\93\ The Arkansas Regional Haze SO2
and PM SIP submittal did not revise the RPG for the twenty percent best
days that was included in the 2008 Arkansas Regional Haze SIP.
---------------------------------------------------------------------------

    \91\ See spreadsheet, sip-rev-rpg-calcs.xlsx, provided at
https://www.adeq.state.ar.us/air/planning/sip/regional-haze.aspx.
    \92\ See page 54 of the Arkansas Regional Haze SO2
and PM SIP revision.
    \93\ See the EPA's proposed approval on November 30, 2018 (83 FR
62204).
---------------------------------------------------------------------------

    Table 6 provides more recent monitored visibility data presented by
the State in the August 8, 2018 SIP revision for the twenty percent
worst days at Caney Creek and Upper Buffalo Wilderness areas.\94\ The
observed values exhibit a consistent downward trend in the
observations. When comparing the revised 2018 RPGs with the observed
five-year visibility trends, Caney Creek and Upper Buffalo are already
realizing more visibility improvement than needed to meet the revised
2018 RPGs. Most recently, the visibility conditions at Caney Creek and
Upper Buffalo during the 2012 to 2016 period were 1.83 dv and 1.95 dv
below the 2018 revised RPGs.
---------------------------------------------------------------------------

    \94\ See spreadsheet, visibility-progress.xlsx, provided at
https://www.adeq.state.ar.us/air/planning/sip/regional-haze.aspx.

                                     Table 6--Visibility at Arkansas Class I Areas for the Twenty Percent Worst Days
                                                                   [Five-Year Average]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Baseline (2000-
                      Class I area                          2004) (dv)      (2005-2009)     (2007-2011)     (2009-2013)     (2012-2016)    2018 Revised
                                                                               (dv)            (dv)            (dv)            (dv)          RPGs (dv)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Caney Creek Wilderness..................................           26.36           25.33           23.00           22.22           20.64           22.47
Upper Buffalo Wilderness................................           26.27           25.86           24.15           22.15           20.56           22.51
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The EPA proposes to conclude that the State has adequately
addressed the applicable provisions under 40 CFR 51.308(g) with respect
to visibility conditions at Arkansas' Class I areas. The State provided
five-year average baseline visibility conditions from 2000 to 2004, the
five-year average visibility conditions from 2007 to 2011, and the
five-year average visibility conditions for 2005 to 2009. The State
calculated the change in visibility between the baseline average and
the most recent five-year average available (2007 to 2011). The results
were tabulated for the twenty percent worst and best days and then
compared to the 2018 RPGs to determine the amount of visibility
improvement achieved. Caney Creek and Upper Buffalo Wilderness areas
have both demonstrated improved visibility for the most impaired and
least impaired days since 2001. Based on the five-year rolling
averages, both wilderness areas have already exceeded the amount of
visibility improvement needed to meet the more stringent revised 2018
RPGs for the twenty percent worst days. Analysis of the visibility data
from Caney Creek and Upper Buffalo Wilderness areas also shows that the
goal of no visibility degradation on the twenty percent best days has
been achieved.

E. Emission Tracking

    In its progress report, ADEQ presented categorized NEI emission
inventories for 2002, 2005, 2008, and 2011, as well as CENRAP projected
inventories for 2018. The pollutants inventoried included
SO2, NOX, NH3, VOC, PM2.5,
and PM10. The inventories were categorized for all major
visibility-impairing pollutants under major anthropogenic source
groupings. The anthropogenic source categorization included point and
non-point EGUs; on and non-road mobile sources; area sources; fugitive
and road dust; fire, and agricultural/biogenic sources. The 2008 and
2011 NEI inventories were the most recent comprehensive inventories of
updated actual emissions available at the time the State prepared its
progress report. The State, therefore, emphasized those NEI inventories
in the progress report and then compared the categorized inventory
changes from 2011 to the 2002 baseline emissions.\95\ A summary of the
total state NEI emissions from the progress report can be seen below in
Table 7 along with more recent complementary data from 2014 provided by
the EPA to show emission trends going past 2011.
---------------------------------------------------------------------------

    \95\ See Table 5.1 (page 46-47) of the progress report.

                                                    Table 7--Comparison of Total State NEI Emissions
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                          Year                                  SO2             NOX             NH3             VOC            PM2.5           PM10
--------------------------------------------------------------------------------------------------------------------------------------------------------
2002....................................................         126,707         239,487         124,297         228,032          62,505         243,372
2005....................................................         126,707         239,487         134,156         312,648         108,362         296,149
2008....................................................          94,113         247,734         131,710       1,427,040         124,829         443,213
2011....................................................          95,123         260,737         132,940       1,643,979         144,191         467,527
2014 *..................................................          91,033         212,638          76,114       1,625,837         119,957         369,682
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Provided by the EPA from the EIS gateway database.

    The NEI emissions increased from 2002 to 2011 except for
SO2 emissions. The State explained in the progress report
that the total SO2 emissions decreased as a result of
phasing in low sulfur (500 ppm) Ultra-Low Sulfur Diesel fuels for
nonroad, locomotive, and marine engines beginning in 2007. The emission
increase for the remaining pollutants in table 7 was due to an emission
rise in 2011 that happened across the board. Fires were the primary
cause of the emission increase for SO2, PM2.5,
PM10, and NH3, but road dust also impacted PM
during that time. Area sources were the chief contributor to
NOX increases and agricultural sources contributed the most
to VOC emission increases in 2011.\96\ The State believes that much of
the increases for NOX, PM10, and PM2.5
may have been due to the use of newer modeling methodologies that were
not available when the baseline projections were developed in 2002.\97\
The State also observed that NOX and PM2.5
emissions trended downward in the point EGU category between 2002 and
2011.\98\
---------------------------------------------------------------------------

    \96\ See Table 5.1 of the progress report (page 46 to 47).
    \97\ See page 47 of progress report. Emission changes were seen
in the on-road mobile source inventory between 2008 and 2011 as a
result of the transition from EPA's MOBILE6 model to the Motor
Vehicle Emission Simulator (MOVES) model for estimation of
emissions. Increases in on-road mobile source PM10 and
PM2.5 emissions have been documented as part of the new
model's estimation methodology. The transition to MOVES model
estimation methodology also resulted in increased NOX
emissions for on-road mobile sources. Modeling figures for fires
also accounted for a major portion of the estimated emission
increase for PM2.5 from 2008 to 2011.
    \98\ See Table 5.4 of the progress report (Page 51).
---------------------------------------------------------------------------

    The updated 2014 NEI data in table 7 shows that the total state
emissions decreased from 2011 for all of the visibility impairing
pollutants except VOCs, which slightly increased.\99\ The source
categories in table 8 below (provided by the EPA) are the driving
factors causing the total NEI emission decreases from 2011 to
2014.\100\ When comparing the individual categories, agricultural/
biogenic and area source emissions account for the majority of emission
increases from 2011 to 2014 with small increases also resulting from
fugitive dust and point sources. Those increases are offset, though, by
large reductions in the rest of the categories, resulting in overall
net decreases of all pollutant emissions. Although fire emissions had a
big impact on visibility impairing pollutants in 2011, there was a
major improvement in 2014 indicated by reductions of all pollutants
except NH3, especially PM and VOC emissions.
PM10, PM2.5, and VOC emissions from fire showed
large reductions of 26,678 tpy, 22,058 tpy, and 49,182 tpy
respectively. Likewise, road dust previously impacted PM levels in 2011
but showed substantial reductions of 105,187 tpy PM10 and
11,448 tpy PM2.5 in 2014. Point sources had increases of
NOX, SO2, NH3, and VOC emissions but
they netted out due to overall net decreases from the other source
categories. Lastly, mobile emissions reduced for every pollutant except
a small inconsequential non-road mobile increase for NH3.
NOX and VOC exhibited the most mobile emission reductions of
15,124 tpy NOX and 8,397 tpy VOC.
---------------------------------------------------------------------------

    \99\ See 70 FR 39162. VOC emissions did increase since 2008, but
CENRAP modeling demonstrated that VOCs are not significant
contributors to visibility impairment at Caney Creek and Upper
Buffalo Wilderness areas.
    \100\ As reported in the online EPA Emissions Inventory System
(EIS) Gateway database.

                                                       Table 8--2014 Emission Data (tpy) and the Category Changes Since 2011 for Arkansas
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
            Category                         NOX                       SO2                       PM10                      PM2.5                     NH3                         VOC
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Agricultural/Biogenic...........  18,588 (-6,744).........  0.......................  153,477 (+17,805).........  30,009 (+2,875)........  58,981 (-58,976).......  1,342,516 (-119,084)
Area \101\......................  15,472 (-14,701)........  321 (-1,684)............  26,423 (+15,513)..........  16,455 (+8,428)........  905 (+479).............  69,117 (-10,484)
Fires...........................  8,743 (-5,897)..........  4,624 (-2,946)..........  59,755 (-26,678)..........  50,198 (-22,058).......  13,094 (+824)..........  133,197 (-49,182)
Fugitive Dust...................  0.......................  0.......................  17,143 (+1,953)...........  1,714 (+195)...........  0......................  0
Road Dust.......................  0.......................  0.......................  97,066 (-105,187).........  11,373 (-11,448).......  0......................  0
Non-road Mobile.................  18,819 (-3,337).........  41 (-16)................  1,926 (-391)..............  1,835 (-376)...........  28 (+1)................  23,204 (-6,161)
On-road Mobile..................  79,428 (-11,787)........  333 (-27)...............  4,001 (-970)..............  2,436 (-545)...........  1,235 (-72)............  33,171 (-2,236)
Point Sources...................  71,588 (+186)...........  85,714 (+792)...........  9,891 (-560)..............  5,936 (-846)...........  1,871 (+610)...........  24,632 (+1,821)
                                 ---------------------------------------------------------------------------------------------------------------------------------------------------------------
    Total Emission Change.......  -42,279.................  -3,881..................  -98,515...................  -23,775................  -57,134................  -185,326
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* The numbers in parentheses indicate an increase (+) or decrease (-) in emissions from 2011.

    The EPA proposes to conclude that the State has adequately
addressed the applicable provisions under 40 CFR 51.308(g). The State
tracked changes in emissions by category across the entire emission
inventory and the results show that the emissions from SO2,
NOX, and PM, the main contributors of regional haze in
Arkansas, have all decreased since the 2008 SIP submittal. The analysis
provides the most recent period for which data was available in
practical terms (2008 to 2011) from when the State submitted its
regional haze SIP.\102\ The EPA provided an additional update

with 2014 NEI data to complement the State's report. These data
indicate that overall emissions of all visibility impairing pollutants
have reduced from 2011 to 2014. SO2, NOX, and PM
emissions have continued to show a downward trend since the 2008
submittal.\103\ As discussed in section II.C. in this proposed
rulemaking, more recent available data shows that SO2 and
NOX emissions from EGU point sources in the state have
decreased from the baseline levels in 2002, especially since 2015. The
EPA concludes that the State presented an adequate analysis tracking
emission trends for the key visibility impairing pollutants across
Arkansas.
---------------------------------------------------------------------------

    \101\ See Page 45 of the progress report.
    \102\ While ideally the five-year period to be analyzed for
emission inventory changes is the time-period since the current
regional haze SIP was submitted, there is an inevitable time lag in
developing and reporting complete emissions inventories once
quality-assured emissions data becomes available. Therefore, there
is some flexibility in the five-year time-period that states can
select.
    \103\ See 70 FR 39162. VOC emissions did increase since 2008,
but CENRAP modeling demonstrated that VOCs are not significant
contributors to visibility impairment at Caney Creek and Upper
Buffalo Wilderness areas.
---------------------------------------------------------------------------

F. Assessment of Changes Impeding Visibility Progress

    The State indicated in the progress report \104\ that there were no
significant changes in anthropogenic emissions that limited or impeded
progress in reducing pollutant emissions and improving visibility as
contemplated by the 2008 Arkansas Regional Haze SIP. The State's Class
I areas showed overall downward trends in visibility impairment. The
State's current analysis of emission reductions and categorized
inventories presented in the progress report, along with more recent
emission data evaluated by the EPA in this action (see sections II.C
and II.E), show that no significant changes in emissions within the
state are occurring to impede visibility improvement or adversely
affecting the two Class I areas in Arkansas. There are also no
significant emission changes from sources outside of Arkansas that are
adversely affecting Arkansas' Class I areas. Through consultation with
adjacent states, it was determined and agreed upon that additional
emission reductions from other states are not necessary to address
visibility impairment at Caney Creek and Upper Buffalo Wilderness areas
for the first implementation period.\105\ The participating states also
determined before the 2008 SIP submittal through regional modeling that
Missouri's Class I areas were expected to be on course to meet their
respective 2018 RPGs. The current data confirms the projected trend and
shows that all Class I areas within and outside the state impacted by
Arkansas emissions are now currently meeting their RPGs for the first
implementation period as discussed in section II.G of this action. No
significant changes in emissions have limited or impeded progress in
improving visibility. The EPA proposes to conclude that the State has
adequately addressed the applicable provisions under 40 CFR 51.308(g)
regarding assessing any changes that could impede visibility progress.
---------------------------------------------------------------------------

    \104\ See Page 54 of the progress report.
    \105\ See 76 FR 64196.
---------------------------------------------------------------------------

G. Assessment of Current Strategy To Meet RPGs

    In its progress report, the State assessed the strategies in the
2008 Arkansas Regional Haze SIP based upon projected emissions and
modeling results. The State determined that the strategies were
sufficient to enable Arkansas and other states with Class I areas
affected by emissions from Arkansas to meet all established RPGs. The
evaluation set forth by the State in the progress report for the Class
I areas in Arkansas was based on the RPGs established in the 2008
Arkansas Regional Haze SIP that were disapproved in the 2012 action.
    As part of the 2018 Arkansas Regional Haze SO2 and PM
SIP revision, Arkansas reevaluated its RPGs and long-term strategy. The
2008 SIP RPGs for the twenty percent worst days were recently replaced
by the State with new revised RPGs \106\ defined in the Arkansas
Regional Haze SO2 and PM SIP revision.\107\ The 2018 RPGs
for Caney Creek and Upper Buffalo were revised slightly downward from
the 2008 SIP RPGs to 22.47 dv and 22.51 dv for the twenty percent worst
days. The revised 2018 RPGs were estimated based on scaling Arkansas
SO4\2-\ and NO3\-\ point source impacts from
CENRAP's 2018 CAMx modeling results by the change in emissions of NOx
and SO2 due to revised regional haze SIP controls required
by the end of 2018. The State made updates to reflect the most recent
three years of data (2014 to 2016) for emissions and heat inputs that
were used for Arkansas EGUs. Currently, both Caney Creek and Upper
Buffalo Wilderness areas are achieving greater visibility improvement
than the revised 2018 RPGs.\108\ Based on available monitored data, the
current visibility trendlines are below their respective 2018 RPGs from
the baseline conditions and visibility is continuing to improve.
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    \106\ See the sip-rev-rpg-calcs.xlsx spreadsheet at https://www.adeq.state.ar.us/air/planning/sip/regional-haze.aspx.
    \107\ See page 48 of the Arkansas Regional Haze SO2
and PM SIP revision.
    \108\ See Figures 11 and 12 on pages 50 to 52 of the Arkansas
Regional Haze SO2 and PM SIP revision.
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    Sources in Arkansas also impact Hercules Glades and Mingo
Wilderness Class I areas in Missouri. Arkansas stated in its progress
report that the 2018 RPGs for Missouri's Class I areas would be met,
but it did not restate those 2018 RPGs or compare them to the available
monitored data. Recent information for these areas, however,
complements the State's analysis and shows that Missouri is indeed
currently on track to achieve its 2018 RPGs for Hercules Glades and
Mingo Wilderness.\109\ The 2012 to 2016 five-year rolling average of
observed visibility impairment for the twenty percent haziest days at
Hercules Glades Wilderness Area is 20.72 dv (2.34 dv below Missouri's
2018 RPG). The 2012 to 2016 five year-rolling average of observed
visibility impairment for the twenty percent haziest days at Mingo
Wilderness Area is 22.34 dv (1.37 dv below Missouri's 2018 RPG goal).
Arkansas concluded that the visibility improvement observed at the
IMPROVE monitors indicates that sources in Arkansas are not interfering
with the achievement of Missouri's 2018 RPGs for Hercules Glades and
Mingo Wilderness Areas. Therefore, we are proposing to find that
Arkansas' implementation plan is sufficient to ensure that other
states' visibility RPGs for the first planning period for their
respective Class I areas are being met.
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    \109\ See Visibility Progress_Update_2016.xlsx in the docket of
this action.
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    The EPA proposes to conclude that the State has adequately
addressed the applicable provisions under 40 CFR 51.308(g) to assess
the current strategy to meet RPGs. The State has assessed the
implementation plan in place at the time the progress report was
submitted, and we find that the implementation plan as it currently
exists is sufficient to enable the state of Arkansas and other nearby
states to meet their RPGs. The realized and planned controls and
reductions that form the current strategy for this first implementation
period are sufficient to meet the revised RPGs as established in the
Arkansas Regional Haze SO2 and PM SIP revision. Both Class I
areas in Arkansas are currently meeting the revised 2018 RPGs for the
twenty percent worst days. Visibility data from Caney Creek and Upper
Buffalo Wilderness areas also show that the goal of no visibility
degradation for the twenty percent best days is being achieved.
Missouri's two Class I areas are also on track to achieve their
visibility reduction goals.

H. Review of Visibility Monitoring Strategy

    The monitoring strategy for regional haze in Arkansas relies upon
participation in the IMPROVE \110\ network, which is the primary
monitoring network for regional haze nationwide. The IMPROVE network
provides a long-term record for tracking visibility improvement or
degradation. Arkansas currently relies on data collected through the
IMPROVE network to satisfy the regional haze monitoring requirement as
specified in 40 CFR 51.308(d)(4) of the Regional Haze Rule.
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    \110\ See 64 FR 35715 (July 1, 1999). Data from IMPROVE show
that visibility impairment caused by air pollution occurs virtually
all the time at most national parks and wilderness areas. The
average visual range in many Class I areas (i.e., national parks and
memorial parks, wilderness areas, and international parks meeting
certain size criteria) in the western United States is 100-150 km,
or about one-half to two-thirds of the visual range that would exist
without anthropogenic air pollution. In most of the eastern Class I
areas of the United States, the average visual range is less than 30
km, or about one-fifth of the visual range that would exist under
estimated natural conditions.
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    In its progress report, Arkansas summarized the existing IMPROVE
monitoring network and its intended continued reliance on IMPROVE for
visibility planning. In Arkansas, there are two IMPROVE sites. The
first IMPROVE site is located in Polk County at the Ouachita National
Forest and represents the 14,460 acres of the Caney Creek Wilderness.
The second IMPROVE site is located in Newton County at the Ozark
National Forest and represents the 11,801 acres of the Upper Buffalo
Wilderness area, including the original Wilderness and the additions to
it.\111\ Arkansas is committed to meeting the requirements under 40 CFR
51.308(d)(4)(iv), and reports annually to the EPA visibility data for
each of Arkansas' Class I areas. For the progress report, Arkansas has
evaluated its monitoring network and found that there have not been any
changes from the 2008 Arkansas Regional Haze SIP network. Arkansas
reaffirmed its continued reliance upon the IMPROVE monitoring network.
Arkansas also explained the importance of the IMPROVE monitoring
network for tracking visibility trends at its Class I areas and
identified no expected changes in this network. The EPA proposes to
conclude that the State has adequately addressed the applicable
provision under 40 CFR 51.308 for a visibility monitoring strategy.
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    \111\ See Table 8.1 in the progress report (page 63).
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I. Determination of Adequacy of Existing Implementation Plan

    Arkansas noted that it was committed to correcting the portions of
the 2008 Arkansas Regional Haze SIP that were disapproved by the EPA
and provided a negative declaration stating that no additional controls
were necessary during the first implementation period.\112\ Since the
progress report's submission in 2015, the EPA promulgated a FIP and the
State subsequently submitted two SIP revisions to fulfill its
commitment to address the disapproved portions identified in the 2012
action (the 2017 Arkansas Regional Haze NOX SIP revision and
the 2018 Arkansas Regional Haze SO2 and PM SIP
revision).\113\ When considering the new SIP requirements; the SIP
requirements that we proposed for approval; the remaining FIP elements;
the visibility and emission information provided in the progress
report; and the more recent data evaluated by the EPA; it is clear that
the implementation plan is adequate to meet its emission reductions and
visibility goals for the first implementation period. Current
visibility conditions in Arkansas have improved beyond the more
stringent 2018 RPGs that were introduced in the 2018 Arkansas Regional
Haze SO2 and PM SIP revision. Visibility has also improved
at both Missouri Class I areas affected by Arkansas sources. Lastly,
the updated emission trends show that SO2, NOX,
and PM emissions (the main contributors to regional haze in Arkansas)
have all been decreasing. The Arkansas Regional Haze NOX SIP
revision,\114\ the Arkansas Regional Haze SO2 and PM SIP
revision (if EPA's proposed approval is finalized),\115\ and the
remaining part of the FIP that addresses the BART and associated long-
term strategy requirements for Domtar together fully address the
deficiencies of the 2008 Arkansas Regional Haze SIP. Because the SIP
and FIP will ensure the control of SO2 and NOX
emission reductions relied upon by Arkansas and other states in setting
their RPGs, the EPA is proposing to approve Arkansas' finding that
there is no need for revision of the existing implementation plan to
achieve the RPGs for the Class I areas in Arkansas and in nearby states
impacted by Arkansas sources. We, therefore, propose to approve
Arkansas' negative declaration under 40 CFR 51.308(h) that no
additional controls are needed.
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    \112\ Specifically, the EPA disapproved certain BART compliance
dates; the State's identification of certain BART-eligible sources
and subject-to-BART sources; certain BART determinations for
NOX, SO2, and PM; the reasonable progress
analysis and RPGs; and a portion of the long-term strategy. The
remaining provisions of the 2008 Arkansas Regional Haze SIP were
approved.
    \113\ See final action approved on February 12, 2018 for the
Arkansas Regional Haze NOX SIP revision (83 FR 5927) and
the EPA's proposed approval on November 30, 2018 for the Arkansas
Regional Haze SO2 and PM SIP revision (83 FR 62204).
    \114\ Final action approved on February 12, 2018 (83 FR 5927).
    \115\ Proposed approval on November 30, 2018 (83 FR 62204).
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J. Consultation With Federal Land Managers

    The Regional Haze Rule requires the State to provide the designated
Federal Land Managers (FLMs) with an opportunity for in-person
consultation at least sixty days prior to holding any public hearings
on a SIP revision for the first implementation period. Arkansas invited
the FLMs to comment on its draft progress report on April 25, 2014, for
a sixty-day comment period ending June 24, 2014, that was extended
until June 27, 2014, per FLM request. The FLM's comments and Arkansas'
responses are presented in Appendix A of the progress report. ADEQ also
engaged in multiple conference calls arranged by CenSARA for the
central states with the designated FLMs which took place on February
27, 2012, April 30, 2013, July 30, 2013, August 13, 2013, and September
12, 2013. The EPA proposes to conclude that Arkansas has adequately
addressed the applicable FLM provisions under 40 CFR 51.308(i).

III. The EPA's Proposed Action

    The EPA is proposing to approve the State of Arkansas' regional
haze five-year progress report SIP revision (submitted June 2, 2015) as
meeting the applicable regional haze requirements set forth in 40 CFR
51.308(g). The EPA is also proposing to approve the State of Arkansas'
determination of adequacy under 40 CFR 51.308(h) that no additional
controls are needed. Lastly, the EPA is proposing to find that the
State of Arkansas fulfilled its requirement in 40 CFR 51.308(i)
regarding state coordination with FLMs.

IV. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely proposes to approve state law as meeting Federal
requirements and does

not impose additional requirements beyond those imposed by state law.
For that reason, this action:
     Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Orders
12866 (58 FR 51735, October 4, 1993), 13563 (76 FR 3821, January 21,
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
     Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
     Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA; and
     Does not provide EPA with the discretionary authority to
address, as appropriate, disproportionate human health or environmental
effects, using practicable and legally permissible methods, under
Executive Order 12898 (59 FR 7629, February 16, 1994).In addition, the
SIP is not approved to apply on any Indian reservation land or in any
other area where EPA or an Indian tribe has demonstrated that a tribe
has jurisdiction. In those areas of Indian country, the proposed rule
does not have tribal implications and will not impose substantial
direct costs on tribal governments or preempt tribal law as specified
by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Best Available
Retrofit Technology, Incorporation by reference, Intergovernmental
relations, Nitrogen oxide, Ozone, Particulate matter, Reporting and
recordkeeping requirements, Regional haze, Sulfur dioxide, Visibility,
Volatile organic compounds.

    Authority:  42 U.S.C. 7401 et seq.

    Dated: March 21, 2019.
Anne Idsal,
Regional Administrator, Region 6.
[FR Doc. 2019-05861 Filed 3-27-19; 8:45 am]
 BILLING CODE 6560-50-P