[Federal Register Volume 79, Number 241 (Tuesday, December 16, 2014)]
[Proposed Rules]
[Pages 74817-74892]
[FR Doc No: 2014-28930]

Vol. 79

Tuesday,

No. 241

December 16, 2014

Part II

 Environmental Protection Agency

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40 CFR Part 52

 Approval and Promulgation of Implementation Plans; Texas and Oklahoma;
Regional Haze State Implementation Plans; Interstate Transport State
Implementation Plan to Address Pollution Affecting Visibility and
Regional Haze; Federal Implementation Plan for Regional Haze and
Interstate Transport of Pollution Affecting Visibility; Proposed Rule

Federal Register / Vol. 79 , No. 241 / Tuesday, December 16, 2014 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2014-0754; FRL-9920-11-Region-6]

Approval and Promulgation of Implementation Plans; Texas and
Oklahoma; Regional Haze State Implementation Plans; Interstate
Transport State Implementation Plan To Address Pollution Affecting
Visibility and Regional Haze; Federal Implementation Plan for Regional
Haze and Interstate Transport of Pollution Affecting Visibility

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
partially approve and partially disapprove a revision to the Texas
State Implementation Plan (SIP) received from the State of Texas on
March 31, 2009, that addresses regional haze for the first planning
period from 2008 through 2018. This SIP revision was submitted to
address the requirements of the Clean Air Act (CAA) and EPA's rules
that require states to prevent any future, and remedy any existing,
manmade impairment of visibility to assure reasonable progress toward
the national goal of achieving natural visibility conditions in Class I
areas. The EPA is proposing to partially approve this SIP revision as
meeting certain requirements of the regional haze program, including
the majority of the requirement to procure and install the Best
Available Retrofit Technology (BART) at certain categories of existing
major stationary sources built between 1962 and 1977. The EPA is also
proposing to partially disapprove the SIP revision for not adequately
addressing other requirements of the regional haze program related to
reasonable progress, the long-term strategy, and the calculation of
natural visibility conditions. The EPA is also proposing to disapprove
SIP revisions submitted by Texas for the purpose of addressing the
requirements of the CAA regarding interference with other states'
programs for visibility protection for the 1997 fine particulate matter
(PM2.5) National Ambient Air Quality Standards (NAAQS), the
1997 ozone NAAQS, the 2006 PM2.5 NAAQS, the 2008 ozone
NAAQS, the 2010 Nitrogen Dioxide (NO2) NAAQS, and the 2010
Sulfur Dioxide (SO2) NAAQS.
    Finally, the EPA is proposing to partially disapprove a revision to
the Oklahoma SIP submitted in February 19, 2010, that addresses
regional haze for the first planning period. Specifically, EPA is
proposing to disapprove Oklahoma's Reasonable Progress Goals (RPGs) for
the Wichita Mountains Class I area.
    The EPA is proposing a Federal Implementation Plan (FIP) for each
Texas and Oklahoma to remedy certain deficiencies in the SIP. The
proposed FIP would implement SO2 emission limits on fifteen
Texas sources as part of a long-term strategy for making reasonable
progress at three Class I areas in Texas and Oklahoma, sets new RPGs
for the Big Bend, the Guadalupe Mountains, and Wichita Mountains Class
I areas, and substitutes Texas' reliance on the Clean Air Interstate
Rule (CAIR) to satisfy BART requirements at its EGUs with reliance on
CAIR's successor, the Cross-State Air Pollution Rule (CSAPR). Our
proposed FIP for Oklahoma does not establish any additional
requirements on sources within Oklahoma. The EPA is taking this action
under the CAA.
    Comments must be received on or before February 17, 2015.
    Public Hearings. EPA is holding open houses--for the purpose of
providing additional information and informal discussion for our
proposal, and public hearings--to accept oral comments into the record,
as follows:

    Date: Tuesday, January 13, 2015.
    Time: Open House: 1:30 p.m.-3:30 p.m.
    Public hearing: 4:00 p.m.-8:00 p.m. (including short break).
    Location: Eastview Campus, Austin Community College, Building
8500, Room 8500, 3401 Webberville Road, Austin, Texas 78702.

    Date: Thursday, January 15, 2015.
    Time: Open House: 2:30 p.m.-4:30 p.m.
    Public hearing: 5:00 p.m.-7:00 p.m.
    Location: Metro Technology Centers, Springlake Campus, Business
Conference Center Meeting, Room H, 1900 Springlake Drive, Oklahoma
City, Oklahoma 73111.

    The public hearings will provide interested parties the opportunity
to present information and opinions to EPA concerning our proposal.
Interested parties may also submit written comments, as discussed in
the proposal. Written statements and supporting information submitted
during the comment period will be considered with the same weight as
any oral comments and supporting information presented at the public
hearing. We will not respond to comments during the public hearings.
When we publish our final action, we will provide written responses to
all significant oral and written comments received on our proposal. To
provide opportunities for questions and discussion, we will hold an
open house prior to each public hearing. During the open house, EPA
staff will be available to informally answer questions on our proposed
action. Any comments made to EPA staff during an open house must still
be provided orally during one of the public hearings, or formally in
writing within 30 days after completion of the hearings, in order to be
considered in the record.
    At the public hearings, the hearing officer may limit the time
available for each commenter to address the proposal to three minutes
or less if the hearing officer determines it to be appropriate. We will
not be providing equipment for commenters to show overhead slides or
make computerized slide presentations. Any person may provide written
or oral comments and data pertaining to our proposal at the public
hearings. Verbatim English language transcripts of the hearing and
written statements will be included in the rulemaking docket.

ADDRESSES: Submit your comments, identified by Docket No. EPA-R06-OAR-
2014-0754, by one of the following methods:
     Federal e-Rulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments.
     Email<EMAIL_ADDRESS>     Mail: Mr. Guy Donaldson, Chief, Air Planning Section (6PD-
L), Environmental Protection Agency, 1445 Ross Avenue, Suite 1200,
Dallas, Texas 75202-2733.
     Hand or Courier Delivery: Mr. Guy Donaldson, Chief, Air
Planning Section (6PD-L), Environmental Protection Agency, 1445 Ross
Avenue, Suite 1200, Dallas, Texas 75202-2733. Such deliveries are
accepted only between the hours of 8 a.m. and 4 p.m. weekdays, and not
on legal holidays. Special arrangements should be made for deliveries
of boxed information.
     Fax: Mr. Guy Donaldson, Chief, Air Planning Section (6PD-
L), at fax number<PHONE_NUMBER>.
    Instructions: Direct your comments to Docket No. EPA-R06-OAR-2014-
0754. Our policy is that all comments received will be included in the
public docket without change and may be made available online at
www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through www.regulations.gov or email. The
www.regulations.gov Web site is an

``anonymous access'' system, which means we will not know your identity
or contact information unless you provide it in the body of your
comment. If you send an email comment directly to us without going
through www.regulations.gov your email address will be automatically
captured and included as part of the comment that is placed in the
public docket and made available on the Internet. If you submit an
electronic comment, we recommend that you include your name and other
contact information in the body of your comment and with any disk or
CD-ROM you submit. If we cannot read your comment due to technical
difficulties and cannot contact you for clarification, we may not be
able to consider your comment. Electronic files should avoid the use of
special characters, any form of encryption, and be free of any defects
or viruses.
    Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
at www.regulations.gov or in hard copy at the Air Planning Section
(6PD-L), Environmental Protection Agency, 1445 Ross Avenue, Suite 700,
Dallas, Texas 75202-2733. The file will be made available by
appointment for public inspection in the Region 6 FOIA Review Room
between the hours of 8:30 a.m. and 4:30 p.m. weekdays except for legal
holidays. Contact the person listed in the FOR FURTHER INFORMATION
CONTACT paragraph below or Mr. Bill Deese at<PHONE_NUMBER> to make an
appointment. If possible, please make the appointment at least two
working days in advance of your visit. There will be a 15 cent per page
fee for making photocopies of documents. On the day of the visit,
please check in at our Region 6 reception area at 1445 Ross Avenue,
Suite 700, Dallas, Texas.
    The Texas regional haze SIP is available online at: https://www.tceq.texas.gov/airquality/sip/bart/haze_sip.html. It is also
available for public inspection during official business hours, by
appointment, at the Texas Commission on Environmental Quality, Office
of Air Quality, 12124 Park 35 Circle, Austin, Texas 78753.
    The Oklahoma regional haze SIP is available online at: http://www.deq.state.ok.us/AQDnew/rulesandplanning/Regional_Haze/SIP/index.htm. It is also available for public inspection during official
business hours, by appointment, at the Oklahoma Department of
Environmental Quality, Air Quality Division, 707 North Robinson Avenue,
Oklahoma City, OK 73102.

FOR FURTHER INFORMATION CONTACT: Joe Kordzi, Air Planning Section (6PD-
L), Environmental Protection Agency, Region 6, 1445 Ross Avenue, Suite
700, Dallas, Texas 75202-2733, telephone<PHONE_NUMBER>; fax number 214-
665-7263; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean the EPA.

Table of Contents

I. Background
    A. Regional Haze
    B. Interstate Transport of Air Pollutants and Visibility
Protection
    C. Our Prior Limited Disapproval of Texas' Regional Haze
Concerning CAIR
II. Why are we acting on the Texas and Oklahoma Regional Haze SIPs
simultaneously?
III. Summary of Our Proposed Actions
    A. Texas
    B. Oklahoma
IV. Discussion of the Regional Haze Rule Requirements as They Relate
to Visibility Transport
    A. Introduction
    B. Statutory and Regulatory Background
    C. Our Interpretation of 40 CFR 51.308(d)(1) and (d)(3)
V. Our Analysis of and Proposed Action on the Texas Regional Haze
SIP
    A. Affected Class I Areas
    B. Determination of Baseline, Natural, and Current Visibility
Conditions
    1. Estimating Natural Visibility Conditions
    2. Estimating Baseline Visibility Conditions
    3. Natural Visibility Impairment
    4. Uniform Rate of Progress
    5. Reasonable Progress Goal Minimum
    C. Evaluation of Texas' Reasonable Progress Goals
    1. Establishment of the Reasonable Progress Goals
    2. Texas' Reasonable Progress Four Factor Analysis
    3. Our Analysis of Texas' Reasonable Progress Four Factor
Analysis
    4. Texas' Assertion that Its Progress Goals Are Reasonable
    5. Reasonable Progress Consultation
    D. Evaluation of Texas' BART Determinations
    1. Identification of BART-Eligible Sources
    2. Identification of Sources Subject to BART
    3. Texas' BART Rule
    E. Long-Term Strategy
    1. Texas' Long-Term Strategy Consultation
    2. Texas' Share of Reductions in Other States' Progress Goals
    3. Texas' Technical Basis for Its Long-Term Strategy
    4. Texas' Consideration of the Long-Term Strategy Factors
    F. Coordination of RAVI and Regional Haze Requirements
    G. Monitoring Strategy and Other SIP Requirements
    H. Federal Land Manager Consultation
    I. Periodic SIP Revisions and Five-Year Progress Reports
    J. Future Determination of the Adequacy of the Existing
Implementation Plan
VI. Our Analysis of and Proposed Action on the Remaining Parts of
the Oklahoma Regional Haze SIP
    A. Previous Rulemakings on the Oklahoma Regional Haze SIP
    B. Evaluation of Oklahoma's Reasonable Progress Goals
    1. Establishment of the Reasonable Progress Goals
    2. Reasonable Progress Consultation
    3. The Oklahoma's Reasonable Progress ``Four Factor'' Analysis
    4. Uniform Rate of Progress
    5. Reasonable Progress Goal Minimum
    6. Oklahoma's Assertion That Its Progress Goals Are Reasonable
    7. Our Evaluation of Oklahoma's Reasonable Progress Goals for
the Wichita Mountains
VII. Our Proposed Oklahoma and Texas Regional Haze FIPs
    A. Summary of Our Proposed Texas FIP
    B. Summary of Our Proposed Oklahoma FIP
    C. Technical Overview of Our Proposed Oklahoma and Texas FIPs
    D. Approach to Reasonable Progress and Long-Term Strategy
    1. Time Necessary for Compliance, and the Oklahoma and Texas
RPGs
    2. Energy and Non-Air Quality Environmental Impacts of
Compliance
    3. Remaining Useful Life
    4. Analysis of the PPG Flat Glass Plant
    E. Use of Confidential Business Information
    F. Reasonable Progress and Long-Term Strategy Scrubber and DSI
Cost Results
    G. Reasonable Progress and Long-Term Strategy Scrubber Upgrade
Cost Results
    H. Summary of the Modeled Benefits of Emission Controls
    1. Visibility Benefits of DSI, SDA, and Wet FGD
    2. Visibility Benefits of Scrubber Upgrades
    I. Proposed Reasonable Progress and Long-Term Strategy
Determinations
    1. Proposed Reasonable Progress and Long-Term Strategy
Determination for San Miguel
    2. Proposed Reasonable Progress and Long-Term Strategy
Determination for Units Other Than San Miguel
    3. Proposed Reasonable Progress and Long-Term Strategy
Determination for Scrubber Upgrades
    4. Proposed Reasonable Progress and Long-Term Strategy
Determination for Scrubber Retrofits
    J. Treatment of Potential Error in Scrubber Upgrade Efficiency
Calculations
    K. Proposed Natural Conditions for the Texas Class I Areas
    L. Calculation of Visibility Impairment for the Texas Class I
Areas
    M. Uniform Rates of Progress and the Emission Reductions Needed
To Achieve Them

    N. Reasonable Progress Goals and Demonstration
VIII. Our Evaluation of the Texas Infrastructure SIP Submittals for
Interstate Transport and Visibility Protection
IX. Proposed Determination of Nationwide Scope and Effect
X. Proposed Action
    A. Texas Regional Haze
    B. Oklahoma Regional Haze
    C. Interstate Transport of Air Pollution and Visibility
Protection
XI. Statutory and Executive Order Reviews

I. Background

A. Regional Haze

    Regional haze is visibility impairment that is produced by a
multitude of sources and activities which are located across a broad
geographic area and emit fine particles (PM2.5) (e.g.,
sulfates, nitrates, organic carbon, elemental carbon, and soil dust)
and their precursors. Fine particle precursors react in the atmosphere
to form PM2.5, which also impair visibility by scattering
and absorbing light. Visibility impairment reduces the clarity, color,
and visible distance that one can see. PM2.5 also can cause
serious health effects and mortality in humans and contributes to
environmental effects such as acid deposition and eutrophication.
    Data from the existing visibility monitoring network, the
``Interagency Monitoring of Protected Visual Environments'' (IMPROVE)
monitoring network, show that visibility impairment caused by air
pollution occurs virtually all the time at most national park and
wilderness areas. The average visual range \1\ in many Class I Federal
areas \2\ (i.e., national parks and memorial parks, wilderness areas,
and international parks meeting certain size criteria) in the western
United States is 100-150 kilometers, or about one-half to two-thirds of
the visual range that would exist without anthropogenic air
pollution.\3\ In most of the eastern Class I areas of the United
States, the average visual range is less than 30 kilometers, or about
one-fifth of the visual range that would exist under estimated natural
conditions.\4\
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    \1\ Visual range is the greatest distance, in kilometers or
miles, at which a dark object can be viewed against the sky.
    \2\ Areas designated as mandatory Class I Federal areas (or
Class I areas for short) 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. See CAA section 162(a) below. In accordance with section
169A of the CAA, EPA, in consultation with the Department of
Interior, promulgated a list of 156 areas where visibility is
identified as an important value. See 44 FR 69122 (November 30,
1979). The extent of a mandatory Class I area includes subsequent
changes in boundaries, such as park expansions. CAA section 162(a).
Although States and tribes may designate as Class I additional areas
which they consider to have visibility as an important value, the
requirements of the visibility program set forth in section 169A of
the CAA apply only to ``mandatory Class I Federal areas.'' Each
mandatory Class I Federal area is the responsibility of a ``Federal
Land Manager'' (FLM). See CAA section 302(i).
    We use the term, ``Class I Federal Area'' and ``Class I Area''
interchangeably throughout this document.
    \3\ 64 FR 35714, 35715 (July 1, 1999).
    \4\ Id.
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    In Section 169A of the 1977 Amendments to the CAA, 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,
impairment of visibility in mandatory Class I Federal areas which
impairment results from man-made air pollution.'' \5\ The terms
``impairment of visibility'' and ``visibility impairment'' are defined
in the CAA to include a reduction in visual range and atmospheric
discoloration.\6\ Section 169A(g)(6). In 1980, we promulgated
regulations to address visibility impairment in Class I areas that is
``reasonably attributable'' to a single source or small group of
sources, i.e., ``reasonably attributable visibility impairment''
(RAVI).\7\ These regulations represented the first phase in addressing
visibility impairment. We deferred action on regional haze that
emanates from a variety of sources until monitoring, modeling and
scientific knowledge about the relationships between pollutants and
visibility impairment improved.
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    \5\ CAA section 169A(a)(1).
    \6\ Id.
    \7\ 45 FR 80084 (December 2, 1980).
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    Congress added Section 169B to the CAA in 1990 to address regional
haze issues, and we promulgated regulations addressing regional haze in
1999.\8\ The Regional Haze Rule revised the existing visibility
regulations to integrate into the regulations provisions addressing
regional haze impairment and established a 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 our visibility
protection regulations at 40 CFR 51.300-309. For a detailed description
of those requirements, please refer to Section IV of our previous
action on the Oklahoma regional haze SIP.\9\ The requirement to submit
a regional haze SIP applies to all 50 states, the District of Columbia,
and the Virgin Islands. States were required to submit the first SIP
addressing regional haze visibility impairment for the first ten year
planning period no later than December 17, 2007.\10\ States are
required to submit subsequent SIPs every ten years leading up to 2064,
when the national goal of a return to natural visibility at all Class I
areas is scheduled to be realized.
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    \8\ 64 FR 35714 (July 1, 1999), codified at 40 CFR part 51,
subpart P.
    \9\ 76 FR 16168, 16172-75 (Mar. 22, 2011).
    \10\ 40 CFR 51.308(b).
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    We have acted on all of the states' regional haze SIPs for the
first planning period except for the Texas regional haze SIP and
certain portions of the Oklahoma regional haze SIP. Previously, we
proposed a partial approval and partial disapproval of, and a FIP for
portions of the Oklahoma SIP on March 22, 2011. We finalized that
action on December 28, 2011.\11\ However, for the reasons we explain
below, we did not complete our review of Oklahoma's regional haze SIP.
Due to the special interrelationship of the visibility impairing
transport of pollution between Texas and Oklahoma, we are proposing
action on the remaining portions of the Oklahoma regional haze SIP and
all portions of the Texas regional haze SIP simultaneously.
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    \11\ Proposal: 76 FR 16168 (March 22, 2011). Final: 76 FR 81728
(December 28, 2011).
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B. Interstate Transport of Air Pollutants and Visibility Protection

    Section 110(a)(2)(D)(i)(II) of the CAA requires that states have a
SIP, or submit a SIP revision, containing provisions prohibiting
emissions from within a state from interfering with measures required
to be included in the implementation plan for any other state under the
provisions of Part C of the CAA protecting visibility. Because of the
impacts on visibility from the interstate transport of pollutants, we
interpret this ``good neighbor'' provision in Section 110 of CAA as
requiring states to include in their SIPs measures to prohibit
emissions that would interfere with the reasonable progress goals set
to protect Class I areas in other states. This is consistent with the
requirements in the regional haze program which explicitly require each
state to address its share of the emission reductions needed to meet
the reasonable progress goals for surrounding Class I areas.\12\
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    \12\ 64 FR 35714, 35735 (July 1, 1999).
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    SIPs addressing the good neighbor provisions of Section
110(a)(2)(D)(i)(II) of the CAA are due to us within three years after
the promulgation of a new or revised NAAQS (or within such shorter
period as we may prescribe).\13\ In this action, we propose to take
action on SIP

revisions addressing these good neighbor requirements that were
submitted by Texas following promulgation of the following new or
revised NAAQS: (1) 1997 8-hour ozone, (2) 1997 PM2.5 (annual
and 24 hour), (3) 2006 PM2.5 (24-hour), (4) 2008 8-hour
ozone, (5) 2010 NO2 and (6) 2010 1-hour SO2.
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    \13\ CAA Section 110(a)(1).
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    In 2005, we made a finding that a number of states, including
Texas, did not submit SIPs to address the interstate transport of air
pollution and visibility protection for the 1997 ozone and
PM2.5 NAAQS.\14\ Pursuant to Section 110(c)(1) of the CAA,
this finding started a 24 month time period for us to promulgate a FIP
to address interstate transport of air pollution and visibility
protection, unless a SIP was approved during that time period.
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    \14\ 70 FR 21147 (April 25, 2005).
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    While Texas did not make a timely SIP submittal to address the
interstate transport of air pollution and visibility protection for the
1997 ozone and PM2.5 NAAQS, Texas later made SIP submittals
for all new or revised NAAQS. Specifically, Texas made the following
submittals for new or revised NAAQS that pertain to this action:
     April 4, 2008: 1997 8-hour Ozone, 1997 PM2.5
(24-hour and annual)
     May 1, 2008: 1997 8-hour Ozone, 1997 PM2.5 (24-
hour and annual)
     November 23, 2009: 2006 24-hour PM2.5
     December 7, 2012: 2010 NO2
     December 13, 2012: 2008 8-hour Ozone
     May 6, 2013: 2010 1-hour SO2 (Primary NAAQS)
    We previously acted on portions of the April 4, 2008, and November
23, 2009, Texas SIP submittals that addressed other ``infrastructure''
elements specified in CAA Section 110(a)(2), necessary to implement,
maintain, and enforce the 1997 8-hour ozone and 1997 and 2006
PM2.5 NAAQS.\15\ Texas' submittals addressing transport for
the ozone, PM2.5, NO2 and SO2 NAAQS
may be accessed through the www.regulations.gov Web site (Docket No.
EPA-R06-OAR-2014-0754). Texas indicated in the submittals that its
regional haze SIP fulfilled its obligation for addressing emissions
that would interfere with measures required to be included in the SIP
for any other state to protect visibility. Because of our 2005 finding
that Texas did not make a timely SIP submission for the 1997 ozone and
PM2.5 NAAQS and the expiration of the 24-month FIP clock, we
are obligated to either approve the SIP or, disapprove the SIP and
promulgate a FIP to address interstate transport of air pollution and
visibility protection for Texas emissions for the 1997 ozone and
PM2.5 NAAQS. We believe our proposal addresses this
obligation.
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    \15\ 76 FR 81371 (December 28, 2011).
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C. Our Prior Limited Disapproval of Texas' Regional Haze SIP Concerning
CAIR

    In 2005, we promulgated CAIR, which required 28 states and the
District of Columbia to reduce emissions of SO2 and
NOX that significantly contribute to, or interfere with
maintenance of, the 1997 NAAQS for ozone and PM2.5.\16\ Also
in 2005, we determined that states could rely on CAIR to meet certain
requirements of the Regional Haze Rule.\17\ In particular, we amended
our regulations to provide that states participating in the CAIR cap-
and-trade programs under 40 CFR part 96 pursuant to an EPA-approved
CAIR SIP or states that remain subject to a CAIR FIP in 40 CFR part 97
need not require affected BART-eligible EGUs to install, operate and
maintain BART for emissions of SO2 and NOX.\18\ A
number of states, including Texas, relied on CAIR in their regional
haze SIPs as an alternative to BART for EGU emissions of SO2
and NOX and as an element of their long-term strategy.
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    \16\ 70 FR 25162 (May 12, 2005).
    \17\ 70 FR 39104 (July 6, 2005).
    \18\ 40 CFR 51.308(e)(4) (Aug. 6, 2012).
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    Following our determination in 2005 that states could rely on CAIR
in their regional haze SIPs, the D.C. Circuit Court of Appeals ruled on
several petitions challenging CAIR and remanded CAIR to us.\19\ We
issued a new rule in 2011 to replace CAIR.\20\ The Cross-State Air
Pollution Rule (CSAPR), which replaced CAIR, also requires a number of
states to improve air quality by reducing SO2 and
NOX emissions that cross state lines and significantly
contribute to ozone and/or fine particulate pollution in other states.
We amended our regulations in 2012 to allow CSAPR to serve as an
alternative to SO2 and NOX BART for EGUs in
states in the CSAPR region.\21\ In that same rulemaking, we also
finalized a limited disapproval of the regional haze SIPs of 14 states,
including Texas. Although at the time that we completed our limited
disapproval of these SIPs, CAIR remained in place pursuant to an order
of the D.C. Circuit, we explained that as CAIR had been remanded, it
remained in place temporarily. We also finalized FIPs replacing
reliance on CAIR with reliance on CSAPR as an alternative to BART for
several states but not for Texas.\22\ We more fully explained the basis
for our limited disapproval in that rulemaking and are not taking
comment on our limited disapproval of Texas' regional haze SIP in this
action.
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    \19\ North Carolina v. EPA, 531 F3d 896; modified by 550 F.3d
1176 (D.C. Cir. 2008).
    \20\ 76 FR 48208 (Aug. 8, 2011).
    \21\ 77 FR 33642 (June 7, 2012).
    \22\ 77 FR 33642, 33643. (June 7, 2012)
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II. Why are we acting on the Texas and Oklahoma Regional Haze SIPs
simultaneously?

    As we explained in our 2011 proposed rulemaking on the Oklahoma
regional haze SIP,\23\ we did not take action on Oklahoma's RPGs for
the Wichita Mountains at that time because we first had to evaluate and
act upon the regional haze SIP submitted by Texas. To properly assess
whether Oklahoma had satisfied the reasonable progress requirements of
Section 51.308(d)(1), which include the requirement to set RPGs that
take into account the visibility improvement that will result from
reasonable controls in upwind states, we concluded that we had to
review and evaluate Texas' regional haze SIP before proposing action on
Oklahoma's RPGs.
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    \23\ 76 FR 16168 (March 22, 2011).
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    In our Regional Haze Rule, we stated that ``successful
implementation of the regional haze program will involve long-term
regional coordination among States,'' and that ``States will need to
develop strategies in coordination with one another, taking into
account the effect of emissions from one jurisdiction to air quality in
another.'' \24\ We also noted that RPGs and Long-Term Strategies (long-
term strategies) were intricately linked. The Regional Haze Rule
requires each state submitting a long-term strategy to (1) consult with
other states to develop coordinated emission strategies; (2)
demonstrate that the SIP includes all measures necessary for the state
to obtain its share of the emission reductions needed to meet the RPGs
for the Class I areas it affects; (3) document the technical basis the
state used to determine its apportionment of emission reduction
obligations for the Class I areas it affects; (4) consider all
anthropogenic sources of emissions; and (5) consider a list of seven
other enumerated factors.\25\
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    \24\ 64 FR 35714, 35728 (July 1, 1999).
    \25\ 64 FR 35735 (July 1, 1999).
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    As detailed within this proposal and within our Technical Support
Documents (TSDs), the Texas and Oklahoma regional haze SIPs reveal that
sources in Texas not only significantly impact visibility in the
Wichita Mountains National Wildlife Refuge in

Oklahoma, but that the impacts from Texas point sources are shown to be
several times greater than the impact from Oklahoma's own point
sources. Additionally, information in the Oklahoma Regional Haze SIP
demonstrates that even if every source in Oklahoma were fully
controlled, the Wichita Mountains would not meet the Uniform Rate of
Progress (URP) in 2018 absent additional emission reductions from
upwind sources, principally Texas. As detailed in the Texas SIP,
however, Texas determined that no additional controls at its sources
were warranted during the first planning period to help achieve
reasonable progress at the Wichita Mountains, and Oklahoma did not
request any additional reductions from Texas. As a result, Oklahoma set
RPGs for the Wichita Mountains that do not reflect any reasonable
emission reductions from Texas beyond those that will be achieved by
compliance with other requirements of the CAA.
    This situation demonstrates the difficulties states face when
working to address air pollution problems that do not respect state
borders. It also highlights the respective roles and responsibilities
of upwind and downwind states in addressing visibility impairment in
national parks and wilderness areas. In order to address these
intricately intertwined issues between Oklahoma and Texas, it is
appropriate to review them simultaneously.

III. Summary of Our Proposed Actions

A. Texas

    We propose to partially approve and partially disapprove the
regional haze SIP that Texas submitted to us on March 31, 2009, to meet
the requirements of Section 308 of the Regional Haze Rule.
Specifically, we propose to take action on Texas' BART determinations,
RPGs for the Big Bend and Guadalupe Mountains Class I areas, and long-
term strategy for making reasonable progress at all Class I areas
impacted by emissions from Texas sources. We are also proposing to take
action on the requirements that support these major components of the
state's plan, including Texas' calculations of baseline and natural
visibility conditions, calculation of the URP, identification of
anthropogenic sources of visibility impairment within the state, and
Texas' monitoring strategy. We take very seriously a decision to
propose disapproval of provisions in Texas' plan, as we believe that it
is preferable that all emission control requirements needed to protect
visibility be implemented through the Texas SIP. However, in order to
approve the state's plan, we must be able to find that the state's plan
is consistent with the requirements of the CAA. Our proposed actions
are summarized as follows:
    BART: We propose to approve Texas' determination of which sources
in the state are BART-eligible. We also propose to approve Texas'
determination that none of the state's BART-eligible non-EGUs are
subject to the BART requirements because they are not reasonably
anticipated to cause or contribute to visibility impairment in any
Class I areas. We propose to approve the provisions in Texas' BART
rules at 30 Tex. Admin. Code (TAC) 116.1500--116.1540, with the
exception of 30 TAC 116.1510(d), which relies on CAIR. With respect to
EGUs, we previously issued a limited disapproval of the Texas regional
haze SIP due to Texas' reliance on CAIR to satisfy the BART
requirements. This action does not impact the limited disapproval.
    Reasonable Progress Goals: We propose to disapprove Texas' RPGs for
2018 on the 20-percent least impaired and 20-percent most impaired days
for the Big Bend and Guadalupe Mountains Class I areas. We propose to
find that the state has not demonstrated that its RPGs provide for
reasonable progress towards meeting the national visibility goal.
Specifically, we propose to find that Texas did not satisfy several of
the requirements at Section 51.308(d)(1) with regard to setting RPGs,
most notably the requirement to reasonably consider the four statutory
reasonable progress factors and the requirement to adequately justify
RPGs that are less stringent than the URP.
    Calculations of Baseline and Natural Visibility Conditions: We
propose to approve Texas' calculation of baseline visibility conditions
at the Big Bend and Guadalupe Mountains Class I areas. We propose to
disapprove Texas' calculation of natural visibility conditions at these
Class I areas. Because we propose to disapprove Texas' calculation of
natural visibility conditions, we must also propose to disapprove
Texas' calculation of the URP.
    Long-Term Strategy: We propose to disapprove Texas' long-term
strategy because it does not sufficiently address regional haze
visibility impairment for all Class I areas impacted by Texas sources.
Specifically, we propose to find that Texas did not satisfy several of
the requirements of Section 51.308(d)(3) with regard to developing
long-term strategies. We propose to find that Texas' long-term strategy
does not include all measures necessary to obtain the state's share of
emission reductions needed to make reasonable progress in the Wichita
Mountains Class I area in Oklahoma. We also propose to find that the
technical basis on which Texas relied to determine its apportionment of
emission reduction obligations necessary for achieving reasonable
progress in Wichita Mountains was inadequate. Finally, we propose to
find that Texas did not adequately consider the emissions limitations
and schedules for compliance needed to achieve reasonable progress in
Big Bend, Guadalupe Mountains, or Wichita Mountains. We propose to find
that Texas satisfied the remaining long-term strategy requirements,
including the identification of anthropogenic sources of visibility
impairment and the consideration of emission reductions due to ongoing
air pollution control programs; measures to mitigate the impacts of
construction activities; source retirement and replacement schedules;
smoke management techniques; enforceability; and projected changes in
emissions.
    Monitoring Strategy: We propose to approve Texas' monitoring
strategy.
    To remedy the deficiencies identified above, we propose a FIP for
Texas that consists of a long-term strategy with SO2
emission limits for fifteen coal-fired EGUs that impact visibility in
multiple Class I areas. We propose that these SO2 emission
limits, listed below in Table 1, be met on a 30-boiler-operating-day
rolling average.

      Table 1--Proposed 30-Boiler-Operating-Day SO2 Emission Limits
------------------------------------------------------------------------
                                                           Proposed SO2
                          Unit                            emission limit
                                                            (lbs/MMBtu)
------------------------------------------------------------------------
Scrubber Upgrades:                                        ..............
    Sandow 4............................................            0.20
    Martin Lake 1.......................................            0.12
    Martin Lake 2.......................................            0.12
    Martin Lake 3.......................................            0.11
    Monticello 3........................................            0.06
    Limestone 2.........................................            0.08
    Limestone 1.........................................            0.08
    San Miguel*.........................................            0.60
Scrubber Retrofits:                                       ..............
    Big Brown 1.........................................            0.04
    Big Brown 2.........................................            0.04
    Monticello 1........................................            0.04
    Monticello 2........................................            0.04
    Coleto Creek 1......................................            0.04
    Tolk 172B...........................................            0.06
    Tolk 171B...........................................            0.06
------------------------------------------------------------------------
* As we note elsewhere, we do not anticipate that San Miguel will have
  to install any additional control in order to comply with this
  emission limit.

    We propose to find that these emission limits will result in
emission reductions that will achieve reasonable progress at Big Bend,
the Guadalupe

Mountains, and the Wichita Mountains. These emission limits reflect the
degree of emission reduction that can be achieved by seven
SO2 scrubber retrofits and seven SO2 scrubber
upgrades,\26\ but we do not prescribe how the facilities must meet
these emission limits. We determined that these emission limits are
necessary to achieve reasonable progress based on our four-factor
analysis, which demonstrates that the underlying controls are cost-
effective and result in significant visibility improvement. We propose
that those sources whose proposed emission limits can be achieved by
installing scrubber retrofits must comply with the emission limits
within five years of the effective date of our final rule. We propose
that those sources whose emission limits can be achieved by conducting
scrubber upgrades must comply with the emission limits within three
years of the effective date of our final rule, except for San Miguel,
for which we propose compliance within one year because that unit has
been recently meeting our proposed emission limit. Our proposed FIP
also includes new RPGs for Big Bend and Guadalupe Mountains that we
believe reflect the visibility improvement that will result from the
aforementioned SO2 emission limits, as well as new
calculations of the natural visibility conditions for these Class I
areas.
---------------------------------------------------------------------------

    \26\ As we explain later in our notice, San Miguel has already
upgraded its scrubber and we are proposing that it maintain an
emission rate consistent with recent monitoring data.
---------------------------------------------------------------------------

    We propose to replace Texas' reliance on CAIR to satisfy the BART
requirement for EGUs with reliance on CSAPR.
    Finally, we are also proposing to disapprove the portions of the
infrastructure SIP revisions submitted by Texas to address the
requirements of CAA Section 110(a)(2)(D)(i)(II) with respect to
visibility. This provision of the CAA requires that each state's SIP
have adequate provisions to prohibit in-state emissions from
interfering with measures required to protect visibility in any other
state. We refer to this and similar provisions pertaining to other
states' air quality as the ``good-neighbor'' requirements. We propose
to disapprove portions of the Texas' infrastructure SIP revisions
addressing the ``good-neighbor'' visibility protection requirements for
the 1997 PM2.5 NAAQS, the 1997 ozone NAAQS, the 2006
PM2.5 NAAQS, the 2008 ozone NAAQS, the 2010 NO2
NAAQS, and the 2010 SO2 NAAQS. We propose to find that the
controls in our proposed FIP address the deficiencies in Texas'
regional haze SIP, in combination with the existing controls that Texas
has relied upon in its regional haze SIP, will serve to prevent
emissions from sources in Texas from interfering with measures required
to protect visibility in other states.

B. Oklahoma

    We propose to partially disapprove the regional haze SIP that
Oklahoma submitted to us on February 19, 2010, to meet the requirements
of Section 308 of the Regional Haze Rule. Specifically, we propose to
disapprove Oklahoma's RPGs for 2018 on the 20-percent least impaired
and 20-percent most impaired days for the Wichita Mountains Class I
area. We propose to find that Oklahoma has not adequately demonstrated
that its RPGs provide for reasonable progress towards meeting the
national visibility goal. Specifically, we propose to find that
Oklahoma did not satisfy several of the requirements at Section
51.308(d)(1) with regard to setting RPGs, including the requirement to
adequately consult with other states that may reasonably be anticipated
to cause or contribute to visibility impairment at the Wichita
Mountains and the requirement to adequately justify RPGs that are less
stringent than the URP.
    To remedy the deficiencies identified above, we propose a FIP for
Oklahoma that includes revised RPGs for the Wichita Mountains that
reflect the visibility improvement that will result from the
SO2 emission limits in our long-term strategy for Texas
included in our proposed FIP. Our proposed FIP for Oklahoma does not
establish any additional requirements on sources within the state.

IV. Discussion of the Regional Haze Rule Requirements as They Relate to
Visibility Transport

A. Introduction

    The Texas and Oklahoma regional haze SIPs reveal that sources in
Texas not only impact visibility in the Wichita Mountains National
Wildlife Refuge in Oklahoma, but that the impact from sources in Texas
is several times greater than the impact from Oklahoma's own sources.
Additionally, the Oklahoma regional haze SIP demonstrates that, even if
every source in Oklahoma were fully controlled, the Wichita Mountains
would not meet the URP in 2018 absent additional emission reductions
from upwind sources. Oklahoma and Texas discussed the significant
contribution of sources in Texas to visibility impairment in Wichita
Mountains during the interstate consultation process required by the
Regional Haze Rule. Ultimately, however, Texas determined that no
additional controls at its sources were warranted during the first
planning period to help achieve reasonable progress at the Wichita
Mountains, and Oklahoma did not request any additional reductions from
Texas. As a result, Oklahoma set a reasonable progress goal for Wichita
Mountains that does not achieve the URP and which does not reflect any
emission reductions from Texas beyond those that will be achieved by
compliance with other requirements of the CAA. During the notice-and-
comment period on Oklahoma's proposed SIP, several commenters
criticized Oklahoma for not requesting additional reductions from
Texas. They argued that without such reductions, Oklahoma would not
make reasonable progress toward the national goal at the Wichita
Mountains. In responding to these comments, Oklahoma acknowledged that
sources in Texas had significant impacts on visibility in Wichita
Mountains, but maintained that it did not have the regulatory authority
to require emission reductions in other states. Oklahoma asserted that
only Texas and the EPA could require such reductions.
    This situation demonstrates the difficulties states face when
working to address air pollution problems that do not respect state
borders. It also shows that some uncertainty exists as to the
respective roles and responsibilities of upwind and downwind states in
addressing visibility impairment in national parks and wilderness
areas. Consequently, we believe that it is necessary at this time to
provide clarification to the states on this issue, which hereafter will
be referred to generally as the issue of ``visibility transport.''
Specifically, this section describes the regulatory requirements found
at 40 CFR Sections 51.308(d)(1) and (d)(3), which pertain to RPGs,
interstate consultation, and long-term strategies, and explains how
these requirements apply in the visibility-transport context. This
section also explains how our interpretation of these requirements is
consistent with the provisions of the CAA that seek to prevent
interstate transport of visibility-impairing pollutants,\27\ achieve
reasonable progress toward the national goal,\28\ and address regional
haze.\29\
---------------------------------------------------------------------------

    \27\ 42 U.S.C. Section 7410(a)(2)(D)(i)(II).
    \28\ Id. Section 7491(b)(2).
    \29\ Id. Section 7492.
---------------------------------------------------------------------------

B. Statutory and Regulatory Background

    Congress enacted Section 169A as part of the 1977 CAA Amendments,

declaring as a national goal ``the prevention of any future, and the
remedying of any existing, impairment of visibility in mandatory Class
I areas which impairment results from manmade air pollution.'' \30\ The
term ``mandatory Class I Federal areas'' refers to international parks,
national wilderness areas and memorial parks that exceed 5,000 acres in
size, and national parks that exceed 6,000 acres in size, which were in
existence on August 7, 1977.\31\ Congress directed the Secretary of the
Interior, in consultation with the federal land managers to review all
mandatory Class I Federal areas in the country and to identify those
where visibility was an important value.\32\ Congress then directed us
to confer with the Secretary of the Interior regarding the results of
his review and to promulgate a final list of mandatory Class I Federal
areas that would become subject to the protections of Section 169A.\33\
On November 30, 1979, we finalized a list of 156 mandatory Class I
Federal areas deserving of such protection.\34\
---------------------------------------------------------------------------

    \30\ Id. Section 7491(a)(1).
    \31\ Id. Section 7472(a). Although we often use the term,
``Class I area'' within this document, we mean, ``Mandatory Class I
Federal areas.''
    \32\ Id. Section 7491(a)(2).
    \33\ Id.
    \34\ ``National Visibility Goal for Federal Class I Areas;
Identification of Mandatory Class I Federal Areas Where Visibility
Is an Important Value,'' 44 FR 69,122 (Nov. 30, 1979).
---------------------------------------------------------------------------

    Congress also required us to issue regulations that would provide
guidelines to the states on appropriate techniques and methods for
identifying and measuring visibility impairment; modeling the extent to
which manmade air pollution causes or contributes to such impairment;
and preventing and remedying such pollution and impairment.\35\ In
addition, Congress required our regulations to direct both states that
contained mandatory Class I Federal areas, and states ``the emissions
from which may reasonably be anticipated to cause or contribute to any
impairment of visibility in any such area,'' to include three specific
components in their SIPs.\36\
---------------------------------------------------------------------------

    \35\ 42 U.S.C. Section 7491(b)(1).
    \36\ Id. Section 7491(b)(2).
---------------------------------------------------------------------------

    The first component consists of ``emission limitations, schedules
of compliance and other measures as may be necessary to make reasonable
progress toward meeting the national goal.'' \37\ In determining what
constitutes ``reasonable progress,'' Congress directed states to take
into consideration four statutory factors: (1) The costs of compliance,
(2) the time necessary for compliance, (3) the energy and non-air
quality impacts of compliance, and (4) the remaining useful life of any
existing source subject to such requirements.\38\ The second component
is a requirement that a specified group of older major stationary
sources ``procure, install, and operate, as expeditiously as
practicable . . . the best available retrofit technology,'' more
commonly referred to as BART.\39\ Like the emission limitations
required to make reasonable progress, the emission limitations
representing BART must be determined by taking into consideration a
list of statutory factors.\40\ Lastly, the third component consists of
``a long-term (ten to fifteen years) strategy for making reasonable
progress toward the national goal.'' \41\ This section focuses
specifically on the first and third components: Reasonable progress and
long-term strategies.
---------------------------------------------------------------------------

    \37\ Id.
    \38\ Id. Section 7491(g)(1).
    \39\ Id. Section 7491(b)(2)(A).
    \40\ Id. Section 7491(g)(2).
    \41\ Id. Section 7491(b)(2)(B).
---------------------------------------------------------------------------

    In addition to enacting Section 169A, Congress also amended Section
110 of the CAA to require that all SIPs ``contain adequate provisions
prohibiting . . . any source or other type of emissions activity within
the State from emitting any air pollutant in amounts which will . . .
interfere with measures required to be included in the applicable
implementation plan for any other State . . . to protect visibility.''
\42\ A Senate Committee Report described this provision and similar
requirements as being ``intended to equalize the positions of the
States with respect to interstate pollution by making a source at least
as responsible for polluting another State as it would be for polluting
its own State.'' \43\
---------------------------------------------------------------------------

    \42\ 42 U.S.C. Section 7410(a)(2)(D)(i)(II).
    \43\ S. Rep. No. 95-127, at 41 (1977).
---------------------------------------------------------------------------

    To comply with Congress's mandate, we issued a notice of proposed
rulemaking titled, ``Visibility Protection for Federal Class I Areas,''
on May 22, 1980.\44\ In that notice, we proposed a phased approach to
combating visibility impairment.\45\ In the first phase, we intended to
address visibility impairment attributable to ``a single source or
small group of sources,'' such as plume blight, which could be
identified using visual observation or other simple monitoring
techniques.\46\ We referred to this type of visibility impairment as
``reasonably attributable visibility impairment,'' or RAVI.\47\ Then,
once modeling and monitoring techniques had improved sufficiently, we
intended to engage in a second phase of rulemaking to address the more
complex problem of regional haze,\48\ which we defined as ``visibility
impairment that is caused by the emission of air pollutants from
numerous sources located over a wide geographic area.'' \49\
---------------------------------------------------------------------------

    \44\ ``Visibility Protection for Class I Areas,'' 45 FR 34762
(May 22, 1980).
    \45\ 45 FR 34763/3.
    \46\ Id.
    \47\ 40 CFRCFR Section 51.301.
    \48\ 45 FR 34763/3.
    \49\ 40 CFRCFR Section 51.301.
---------------------------------------------------------------------------

    We finalized our first phase of rulemaking on December 2, 1980.\50\
These regulations, hereafter referred to as the ``RAVI Rule,'' applied
only to the 36 states that contain mandatory Class I Federal areas.\51\
Notably, the RAVI Rule did not apply to upwind states, i.e., those
states, ``the emissions from which may reasonably be anticipated to
cause or contribute to any impairment of visibility in any such area,''
as required by Section 169A.\52\ Among other things, the RAVI Rule
authorized the federal land managers to determine whether visibility
impairment existed in any mandatory Class I Federal area.\53\ The RAVI
Rule also required states to revise their SIPs to assure reasonable
progress toward the national goal, to determine whether BART should be
installed at sources causing visibility impairment certified by the
federal land managers, and to implement long-term strategies for making
reasonable progress.\54\ Ultimately, however, we concluded that
``[p]reliminary indications are that few, if any, existing stationary
facilities will have to retrofit controls,'' and that ``many of the
basic elements of an acceptable [long-term] strategy already exist
within the framework of other air pollution programs.'' \55\
---------------------------------------------------------------------------

    \50\ ``Visibility Protection for Federal Class I Areas,'' 45 FR
80084 (Dec. 2, 1980) (codified at 40 CFR Sections 51.300-307).
    \51\ Id. at 80086/1.
    \52\ See Id. at 80086/1 n.2 (``We did not identify, nor did any
commenters identify any State that did not contain a mandatory Class
I Federal area, but which could contain a source the emissions from
which could reasonably be anticipated to cause or contribute to any
impairment of visibility in any mandatory Class 1 Federal area.'').
    \53\ Id. at 80086/3.
    \54\ Id. at 80086/1.
    \55\ Id. at 80088/3.
---------------------------------------------------------------------------

    Most states did not submit the SIP revisions required by the RAVI
Rule. To resolve a lawsuit brought by environmental litigants, we
promulgated FIPs for these states on November 24, 1987.\56\ Despite the
fact that the federal land managers had certified that visibility
impairment existed in nearly all mandatory Class I Federal areas, we
ultimately determined

that neither BART nor any other controls were necessary to address the
impairment because it was primarily in the form of regional haze and
could not be attributed to a single source or small group of sources at
that time.\57\
---------------------------------------------------------------------------

    \56\ ``State Implementation Plans for Visibility Long-Term
Strategies, Integral Vistas, and Control Strategies,'' 52 FR 45132
(Nov. 24, 1987).
    \57\ Id.
---------------------------------------------------------------------------

    The following year, two decisions of the U.S. Courts of Appeal
placed further emphasis on the fact that visibility impairment was
largely a regional problem. The first case, Vermont v. Thomas,\58\
involved the State of Vermont's challenge to our decision not to take
action on aspects of Vermont's SIP revision that were intended to
address regional haze. In its SIP revision, Vermont had concluded that
visibility impairment at the Lye Brook Wilderness Area was not caused
by plume blight, but rather was comprised of regional haze caused
primarily by sulfur dioxide emissions from out-of-state sources.\59\ As
such, only a reduction program that targeted those out-of-state sources
could assure reasonable progress toward the national visibility goal.
Vermont therefore proposed a long-term strategy that included a
summertime ambient sulfate standard and a 48-state emission reduction
plan.\60\ Vermont also requested that we disapprove and revise the SIPs
of the upwind states that were contributing to regional haze in Lye
Brook and require SIP revisions from those upwind states not currently
subject to the RAVI Rule.\61\ We agreed with Vermont's assessment of
the visibility impairment at Lye Brook, but took no action on those
parts of Vermont's SIP revision aimed at controlling regional haze,
explaining that they were outside the scope of the RAVI Rule.\62\
---------------------------------------------------------------------------

    \58\ Vermont v. Thomas, 850 F.2d 99 (2d Cir. 1988).
    \59\ Id. at 101.
    \60\ Id.
    \61\ Id.
    \62\ ``Approval and Promulgation of Implementation Plans;
Vermont; Visibility in Federal Class I Areas; Lye Brook
Wilderness,'' 52 FR 26973 (July 17, 1987).
---------------------------------------------------------------------------

    In its petition for review, Vermont argued that our decision not to
act on the SIP revision in its entirety violated the CAA and the RAVI
Rule.\63\ The Second Circuit upheld our interpretation, holding that
Vermont's proposed interstate measures were outside the scope of the
RAVI Rule and thus were not subject to federal enforcement under the
CAA. While the court sympathized with Vermont, recognizing ``that
without federal enforcement of Vermont's plan, little, if any, progress
will be made on regional haze at Lye Brook,'' the court determined
that, ``until such time as a federal regional haze program is in place,
Vermont may not impose its standards on upwind States.'' \64\ The court
concluded its opinion by stating that it hoped EPA would act quickly to
create a national program to address regional haze.\65\
---------------------------------------------------------------------------

    \63\ Vermont, 850 F.2d at 103-04.
    \64\ Id. at 104.
    \65\ Id.
---------------------------------------------------------------------------

    The second case, Maine v. Thomas,\66\ involved a citizen suit
brought by seven Northeastern states \67\ and six environmental groups
in which they sought to compel us to promulgate regulations addressing
regional haze. The plaintiffs alleged that we had a nondiscretionary
duty to issue regulations to achieve the national visibility goal by
August 7, 1979,\68\ and that we had violated that duty because the RAVI
Rule did not address regional haze and was therefore not a full
response to the CAA's directive.\69\ The district court rejected that
argument, explaining that we had affirmatively chosen to take a phased
approach to issuing visibility regulations when we promulgated the RAVI
Rule.\70\ The district court therefore viewed the plaintiffs' claim as
a challenge to the RAVI Rule, which was not cognizable under the CAA's
citizen-suit provision. Therefore, the court dismissed the suit for
lack of subject matter jurisdiction.\71\ On appeal, the First Circuit
affirmed the district court's judgment under largely the same
reasoning.\72\ Like the Second Circuit, however, the court noted that
EPA had long delayed in promulgating the promised rulemaking to address
regional haze.\73\
---------------------------------------------------------------------------

    \66\ Maine v. Thomas, 690 F. Supp. 1106 (D. Maine 1988).
    \67\ The States were Connecticut, Maine, Massachusetts, New
Jersey, New York, Rhode Island, and Vermont.
    \68\ See 42 U.S.C. Section 7491(a)(4).
    \69\ Id. at 1108.
    \70\ Id. at 1109.
    \71\ Id. at 1112.
    \72\ Maine v. Thomas, 874 F.2d 883 (1st Cir. 1989).
    \73\ Id. at 885-86.
---------------------------------------------------------------------------

    Reacting to our delay in promulgating regulations to address
regional haze and the courts' decisions in Vermont and Maine,\74\
Congress enacted Section 169B of the CAA as part of the 1990 CAA
Amendments.\75\ Congress designed Section 169B to provide regional
solutions to what was, by definition, a regional problem. To address
the technical limitations identified by us in the RAVI Rule, Congress
required us to ``conduct research to identify and evaluate sources and
source regions of both visibility impairment and regions that provide
predominantly clean air in Class I areas.'' \76\ This research had to
include an expansion of visibility monitoring in Class I areas, an
assessment of the current sources of visibility-impairing pollution,
the adaptation of regional air quality models for the assessment of
visibility, and studies of the atmospheric chemistry and physics of
visibility.\77\ Congress also provided us with the authority to
establish visibility transport regions and commissions whenever we had
reason to believe that ``current or projected interstate transport of
air pollutants from one or more States contributes significantly to
visibility impairment in Class I areas located in the affected
States.'' \78\ Once established, the visibility transport commissions
and their member states were required to assess the available
scientific and technical data regarding visibility impairment and to
report back to us with recommendations regarding how existing statutory
requirements for clean air corridors, new source review, and long-term
strategies could be employed to reduce such impairment.\79\ Finally,
Congress required us to carry out our overdue regulatory
responsibilities under Section 169A, which had to include ``criteria
for measuring `reasonable progress' toward the national goal'' and a
requirement that states revise their SIPs within 12 months.\80\
---------------------------------------------------------------------------

    \74\ See, e.g., 136 Cong. Rec. 2608 (1990) (statement of Sen.
Tim Wirth); 136 Cong. Rec. 2771 (1990) (statement of Rep. Ron
Wyden); 136 Cong. Rec. 2875 (statement of Sen. Brock Adams).
    \75\ 42 U.S.C. Section 7492.
    \76\ Id. Section 7492(a)(1).
    \77\ Id.
    \78\ Id. Section 7492(c)(1).
    \79\ Id. Section 7492(d).
    \80\ Id. Section 7492(e)(1) & (2).
---------------------------------------------------------------------------

    On July 31, 1997, we issued a notice of proposed rulemaking to
revise the existing visibility regulations to address regional haze,
commonly referred to as the ``Regional Haze Rule.'' \81\ In that
notice, we explained that ``[t]he role of regional transport of fine
particles in contributing to . . . regional haze impairment has been
well documented by many researchers and recognized as a significant
issue by many policy makers.'' \82\ Furthermore, we discussed how the
studies required by the 1990 CAA Amendments had revealed that, ``to
varying degrees, emissions from each of the contiguous 48 States
contribute to . . . visibility impairment in at least one mandatory
Class I Federal area.'' \83\ Consequently, we proposed to expand the
applicability of the visibility program to all states for the purpose
of

addressing regional haze.\84\ We explained that this expansion of
applicability was consistent with Section 169A(b)(2), which ``requires
States containing mandatory Class I Federal areas or having emissions
which `may reasonably be anticipated to cause or contribute to any
impairment of visibility in any such area' to revise their visibility
SIPs in order to make reasonable progress toward the national
visibility goal.'' \85\ We noted, however, that the expanded
applicability of the visibility program should not be interpreted to
mean that control strategies would be necessary in all cases. Instead,
states should participate in regional air quality planning groups to
establish and refine their relative contributions to regional haze,
develop regional recommendations on state apportionment of emission
reductions and control measure responsibilities, and identify existing
SIP authorities or other proposed planning requirements necessary to
address states' contributions to visibility problems in other
states.\86\
---------------------------------------------------------------------------

    \81\ ``Regional Haze Regulations,'' 62 FR 41138 (July 31, 1997).
    \82\ Id. at 41139.
    \83\ Id. at 41144-45.
    \84\ Id. at 41144.
    \85\ Id.
    \86\ Id. at 41145.
---------------------------------------------------------------------------

    To satisfy Congress's mandate that we establish criteria for
measuring reasonable progress, we proposed to set presumptive
``reasonable progress targets'' for each Class I area.\87\ Under this
framework, the reasonable progress targets would provide for
perceptible improvement of at least 1.0 deciview \88\ over a 10-year or
15-year period on the 20-percent haziest days and allow no degradation
from the baseline on the 20-percent clearest days.\89\ States could
satisfy their reasonable progress obligations under Section 169A for a
given Class I area by meeting the reasonable progress target for that
area.\90\ States could also develop alternative targets so long as they
justified those targets based on the four statutory factors.\91\
Finally, states would be required to provide a demonstration of
reasonable progress every three years and revise their SIPs as
necessary.\92\
---------------------------------------------------------------------------

    \87\ Id. at 41145-47.
    \88\ As we note in the Regional Haze Rule (64 FR 35725, July 1,
1999), the ``deciview'' or ``dv'' is an atmospheric haze index that
expresses changes in visibility. This visibility metric expresses
uniform changes in haziness in terms of common increments across the
entire range of visibility conditions, from pristine to extremely
hazy conditions.
    \89\ ``Regional Haze Regulations,'' 62 FR 41138 (July 31, 1997)
at 41446.
    \90\ Id.
    \91\ Id.
    \92\ Id. at 41147.
---------------------------------------------------------------------------

    To satisfy the CAA's long-term strategy requirement, we proposed
that states develop a procedure to determine natural and current
visibility conditions for each Class I area for the 20-percent haziest
and 20-percent clearest days.\93\ For Class I areas with existing
anthropogenic impairment greater than 1.0 deciview, states would be
required to adopt measures, including BART and a combination of local
and regional measures from non-BART sources, that would meet the
reasonable progress targets over a three-year period.\94\ We also
proposed that the long-term strategies explicitly address the
contribution by each state needed to meet reasonable progress targets,
explaining that ``each State is ultimately responsible for determining
its contribution to ensure reasonable progress in mandatory Class I
areas affected by its emissions sources and implementing appropriate
emissions control strategies.'' \95\ We further explained that it would
consider this information, as well as any relevant regional planning
analyses, in evaluating a state's long-term strategy.\96\ Finally, we
proposed requirements that would apply if a state did not meet its
reasonable progress targets within a three-year period or when a state
wished to develop alternative progress targets.\97\
---------------------------------------------------------------------------

    \93\ Id. at 41153.
    \94\ Id.
    \95\ Id.
    \96\ Id.
    \97\ Id. at 41153-54.
---------------------------------------------------------------------------

    We finalized the Regional Haze Rule on July 1, 1999.\98\ In the
final rule, we reiterated that ``[s]uccessful implementation of the
regional haze program will involve long-term regional coordination
among States,'' and that ``States will need to develop strategies in
coordination with one another, taking into account the effect of
emissions from one jurisdiction to air quality in another.'' \99\
Consistent with the proposal, we concluded that all states had sources
whose emissions were reasonably anticipated to cause or contribute to
regional haze in at least one Class I area and therefore required all
states to submit regional haze SIPs.\100\
---------------------------------------------------------------------------

    \98\ ``Regional Haze Regulations,'' 64 FR 35714 (July 1, 1999).
    \99\ Id. at 35728.
    \100\ Id. at 35721.
---------------------------------------------------------------------------

    In response to adverse comments, however, we also made significant
changes to the proposal. We eliminated the requirement for presumptive
reasonable progress targets of 1.0 deciview.\101\ Instead, the final
rule called upon states to establish ``reasonable progress goals,'' or
RPGs, for each Class I area.\102\ Like the reasonable progress targets,
the RPGs had to be expressed in deciviews, provide for improvement on
the 20-percent haziest days, and provide for no degradation on the 20-
percent clearest days.\103\ Unlike the reasonable progress targets,
however, the RPGs were to be set on a more flexible basis after
consideration of the statutory factors.\104\ To provide greater equity
between the RPGs set for the more impaired eastern states and the less
impaired western states, we also introduced a new analytical
requirement in the final rule.\105\ This requirement mandated that, for
each Class I area, states (1) determine the amount of progress needed
to reach natural background conditions in 60 years; (2) identify the
URP, over that 60-year period; (3) identify the amount of progress that
would result if the URP were achieved during the planning period; and
(4) identify the emissions measures that would be needed to achieve
that amount of progress and analyze whether the measures were
reasonable based on the statutory factors.\106\ If a state found that
the amount of progress necessary to achieve the URP (or some greater
amount) was reasonable, then the final rule required the state to adopt
that amount of progress as its RPG.\107\ If a state found that the
amount of progress necessary to achieve the URP was unreasonable,
however, then the state could set a less ambitious goal, but only after
providing an analysis and rationale supporting its determination based
on the statutory factors.\108\ Additionally, the final rule included a
new requirement whereby states establishing RPGs had to consult with
other states that were anticipated to contribute to visibility
impairment in the Class I area under consideration and describe in
their SIPs any actions taken to resolve disagreements over the
apportionment of emission measures necessary to achieve the RPGs.\109\
---------------------------------------------------------------------------

    \101\ Id. at 35731.
    \102\ Id.; 40 CFR 51.308(d)(1).
    \103\ 64 FR 35731 (July 1, 1999).
    \104\ 64 FR 35731 (July 1, 1999); 40 CFR 51.308(d)(1)(i)(A).
    \105\ 64 FR 35731 (July 1, 1999).
    \106\ Id. at 35732; 40 CFR 51.308(d)(1)(i)(B).
    \107\ 64 FR 35732 (July 1, 1999).
    \108\ Id.; 40 CFR 51.308(d)(1)(ii).
    \109\ 64 FR 35732 (July 1, 1999); 40 CFR 51.308(d)(1)(iv).
---------------------------------------------------------------------------

    In regard to the long-term strategy requirement, we explained that
the RPGs and the long-term strategies were intricately linked. We
interpreted the term ``long-term strategy'' as ``the control measures
that are needed to ensure reasonable progress, together with a
demonstration that those

measures will provide for reasonable progress during the 10 to 15 year
period.'' \110\ We abandoned our proposal to require states to update
their long-term strategies every three years, providing instead for
longer ten-year revisions.\111\ We also modified the requirements
components of the long-term strategy. In brief, the final rule required
each state submitting a long-term strategy to (1) consult with other
states to develop coordinated emission management strategies,\112\ (2)
demonstrate that the SIP includes all measures necessary for the state
to obtain its share of the emission reductions needed to meet the RPGs
for the Class I areas it affects,\113\ (3) document the technical basis
the state used to determine its apportionment of emission reduction
obligations for the Class I areas it affects,\114\ (4) consider all
anthropogenic sources of emissions,\115\ and (5) consider a list of
seven other enumerated factors.\116\
---------------------------------------------------------------------------

    \110\ 64 FR 35734 (July 1, 1999).
    \111\ Id.; 40 CFR Section 51.308(f).
    \112\ 64 FR 35735 (July 1, 1999); 40 CFR 51.308(d)(3)(i).
    \113\ 64 FR 35735 (July 1, 1999); 40 CFR 51.308(d)(3)(ii).
    \114\ 64 FR 35735 (July 1, 1999); 40 CFR 51.308(d)(3)(iii).
    \115\ 64 FR 35735 (July 1, 1999); 40 CFR 51.308(d)(3)(iv).
    \116\ 64 FR 35736-37 (July 1, 1999); 40 CFR 51.308(d)(3)(v).
---------------------------------------------------------------------------

    Since 1999, the Regional Haze Rule has been the subject of several
revisions and legal challenges. Because none of these revisions or
challenges impacted the regulatory provisions that are the focus of
this section, each is discussed only in brief. In American Corn Growers
v. EPA, the D.C. Circuit invalidated the Regional Haze Rule's BART
provisions because they required states to consider the visibility
benefits of controls on a group-basis, rather than a source-basis.\117\
In 2003, we revised the Regional Haze Rule to incorporate provisions
that would allow certain Western states and eligible Indian Tribes to
implement alternative measures in lieu of BART.\118\ Shortly
thereafter, in Center for Energy and Economic Development (CEED) v.
EPA, the D.C. Circuit invalidated aspects of our 2003 revisions for
using the same type of ``group BART'' approach that the court had
forbade in American Corn Growers.\119\ In 2005, we revised the Regional
Haze Rule a second time in order to remedy the defects with the Rule's
BART provisions that had been identified by the D.C. Circuit in
American Corn Growers.\120\ In that same rulemaking, we promulgated the
BART Guidelines to assist states in determining which sources are
subject to BART and the appropriate level of control for such
sources.\121\ Moreover, as noted above, we added a provision to the
Regional Haze Rule that allowed certain Eastern states to rely on the
CAIR in lieu of requiring BART at fossil fuel-fired EGUs.\122\ Then, in
2006, we revised the Regional Haze Rule a third time in order to remedy
the defects with the Rule's BART-alternative provisions that had been
identified by the D.C. Circuit in CEED.\123\ A few months later, the
D.C. Circuit upheld the 2005 revisions in their entirety in Utility Air
Regulatory Group v. EPA.\124\ The 2006 revisions were never challenged.
Finally, in 2012, we revised the Regional Haze Rule for a fourth time
to replace the provision allowing Eastern states to rely on CAIR in
lieu of BART with a provision allowing for reliance on CAIR's
successor, CSAPR.\125\ Challenges to the 2012 revisions are currently
stayed and remain pending before the D.C. Circuit.\126\
---------------------------------------------------------------------------

    \117\ Am. Corn Growers v. EPA, 291 F.3d 1 (D.C. Cir. 2002).
    \118\ ``Revisions to Regional Haze Rule to Incorporate Sulfur
Dioxide Milestones and Backstop Emissions Trading Program for Nine
Western States and Eligible Indian Tribes Within That Geographic
Area,'' 68 FR 33764 (June 5, 2003).
    \119\ Ctr. for Energy & Econ. Dev. v. EPA, 298 F.3d 653 (D.C.
Cir. 2005).
    \120\ ``Regional Haze Regulations and Guidelines for Best
Available Retrofit Technology (BART) Determinations,'' 70 FR 39104
(July 6, 2005).
    \121\ See Id. at 39156-72 (codified at 40 CFR pt. 51, app. Y).
    \122\ See Id. at 39156 (codified at 40 CFR 51.308(e)(4)).
    \123\ ``Regional Haze Regulations; Revisions to Provisions
Governing Alternative to Source-Specific Best Available Retrofit
Technology (BART) Determinations,'' 71 FR 60612 (Oct. 13, 2006).
    \124\ Util. Air Regulatory Grp. v. EPA, 471 F.3d 1333 (D.C. Cir.
2006).
    \125\ ``Regional Haze: Revisions to Provisions Governing
Alternatives to Source-Specific Best Available Retrofit Technology
(BART) Determinations, Limited SIP Disapprovals, and Federal
Implementation Plans,'' 77 FR 33641 (June 7, 2012).
    \126\ See, e.g., Nat'l Parks Conservation Ass'n v. EPA, No. 12-
1480 (D.C. Cir. Dec. 17, 2012).
---------------------------------------------------------------------------

    During this same period, we also released several guidance
documents pertaining to regional haze and visibility transport, some of
which are helpful to the issues discussed in this section. In an August
3, 2006, document titled, ``Additional Regional Haze Questions,'' we
responded to questions submitted by states as they were developing
their initial regional haze SIP submissions.\127\ Several states had
questions regarding the interstate consultation process and the
respective obligations of upwind and downwind states in setting RPGs
and developing long-term strategies. For example, one state asked
whether there was a protocol for resolving disputes between upwind and
downwind states on apportionment and controls.\128\ In response, we
encouraged the early identification of any potential disputes to allow
all parties ample opportunity to address and document any
disagreements.\129\ One state asked what would happen if a downwind
state set a RPG that required an upwind state to make reductions that
it would not make.\130\ We responded by stating, ``If a State with a
Class I area determines that a contributing State is not doing what is
reasonable to meet the [RPG] set for the area, and has attempted to
resolve this issue, the State with the Class I area should notify EPA
and document this issue in its initial [regional haze] SIP.'' \131\ We
explained that such problems should be brought to our attention as
early in the process as possible.\132\ Finally, a third state asked
whether a downwind state's regional haze SIP could be disapproved
because an upwind state was not doing all it could to meet the RPG for
a downwind Class I area.\133\ We responded by reiterating the
regulatory requirements and noting that, ``If there is a disagreement
among States as to what constitutes reasonable progress, the question
of whether [a downwind State's] or [an upwind State's regional haze]
SIP could be disapproved will depend on the specific[s] of the
situation.'' \134\
---------------------------------------------------------------------------

    \127\ U.S. Envtl. Protection Agency, Additional Regional Haze
Questions (Aug. 3, 2006).
    \128\ Id. at 10.
    \129\ Id.
    \130\ Id. at 11.
    \131\ Id. at 11-12.
    \132\ Id. at 12.
    \133\ Id.
    \134\ Id.
---------------------------------------------------------------------------

    On June 1, 2007, we released a second document to provide guidance
to states on how to set their RPGs and how to decide those measures
necessary to meet the goals.\135\ In the guidance, we provided a
definition for the term ``reasonable progress goal,'' explaining that
RPGs are ``interim goals that represent incremental visibility
improvement over time toward the goal of natural background conditions
and are developed in consultation with other affected States and
Federal Land Managers.'' \136\ The guidance also reiterates that the
long-term strategy and BART emission limitations are inherently linked
to the RPGs:
---------------------------------------------------------------------------

    \135\ Office of Air Quality Planning & Standards, U.S. Envtl.
Protection Agency, Guidance for Setting Reasonable Progress Goals
Under the Regional Haze Program (June 1, 2007).
    \136\ Id. at 1-3.

    The long-term strategy is the compilation of ``enforceable
emissions limitations,

compliance schedules, and other measures as necessary to achieve the
[RPGs],'' and is the means through which the State ensures that its
RPG will be met. BART emissions limits . . . are one set of measures
that must be included in the SIP to ensure that an area makes
reasonable progress toward the national goal, and the visibility
improvement resulting from BART (or a BART alternative) is included
in the development of the RPG.\137\
---------------------------------------------------------------------------

    \137\ Id. at 1-4 (citing to 40 CFR 51.308(d)(3)).

    The majority of the guidance focuses on providing an overview of
the process for developing RPGs, potential methods for identifying
which source categories should be evaluated for controls, and
suggestions for evaluating the four statutory factors with respect to
potentially affected stationary sources.\138\ The guidance reiterates
that the development of the RPG for each Class I area should be a
collaborative process, but acknowledges that the Regional Haze Rule
anticipated that states may not always agree on what measures would be
reasonable or on the appropriateness of a given goal.\139\
---------------------------------------------------------------------------

    \138\ See generally id. at 3-1 to 5-3.
    \139\ Id. at 2-4.
---------------------------------------------------------------------------

    Finally, in a series of three memoranda released in 2006, 2009, and
2013, we provided guidance to the states regarding their obligations
under Section 110(a)(2)(D)(i)(II) with respect to visibility transport,
hereafter referred to as ``prong 4.'' \140\ In the 2006 memo, we
informed states that they could satisfy prong 4 for the 1997 8-hour
ozone and PM2.5 NAAQS by making a simple SIP submission
confirming that it was not possible at the time to assess whether there
was any interference with measures in the SIPs of other states designed
to protect visibility until the states submitted their regional haze
SIPs the following year.\141\ In the 2009 memo, we more plainly stated
that states could satisfy prong 4 for the 2006 24-hour PM2.5
NAAQS so long as they had fully approved regional haze SIPs.\142\ Most
recently, in the 2013 memo, we clarified states' prong 4 obligations
with respect to the 2008 ozone NAAQS, 2010 NO2 NAAQS, 2010
SO2 NAAQS, and 2012 PM2.5 NAAQS.\143\ There, we
reiterated that states could satisfy prong 4 by confirming that they
had fully approved regional haze SIPs.\144\ We reasoned that a fully
approved regional haze SIP necessarily would ensure that emissions from
a state's sources were not interfering with measures required to be
included in other states' SIPs to protect visibility.\145\
Alternatively, we explained that a state could satisfy its prong 4
obligations by including in its infrastructure SIP a demonstration that
emissions within its jurisdiction do not cause interference.\146\ We
clarified that such a submission would need to include measures to
limit visibility-impairing pollutants and ensure that the reductions
were sufficient to comply with any mutually agreed upon RPGs for
downwind Class I areas.\147\
---------------------------------------------------------------------------

    \140\ 42 U.S.C. Section 7410(a)(2)(D)(i) has four separate
requirements or ``prongs,'' the last of which is that SIPs must
address emissions that interfere with another State's measures to
protect visibility.
    \141\ Office of Air Quality Planning & Standards, U.S. Envtl.
Protection Agency, Guidance for State Implementation Plan (SIP)
Submissions to Meet Current Outstanding Obligations Under Section
110(a)(2)(D)(i) for the 8-Hour Ozone and PM2.5 National
Ambient Air Quality Standards, at 9-10 (Aug. 15, 2006).
    \142\ Office of Air Quality Planning & Standards, U.S. Envtl.
Protection Agency, Guidance on SIP Elements Required Under Sections
110(a)(1) and (2) for the 2006 24-Hour Fine Particle
(PM2.5) National Ambient Air Quality Standards (NAAQS),
at 5 (Sept. 25, 2009).
    \143\ Office of Air Quality Planning & Standards, U.S. Envtl.
Protection Agency, Guidance on Infrastructure State Implementation
Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and
110(a)(2) (Sept. 13, 2013).
    \144\ Id. at 33.
    \145\ Id.
    \146\ Id. at 34.
    \147\ Id.
---------------------------------------------------------------------------

C. Our Interpretation of 40 CFR 51.308(d)(1) and (d)(3)

    With this background in mind, we turn now to the provisions of the
Regional Haze Rule that implement the CAA's reasonable progress and
long-term strategy requirements in the visibility-transport context.
Section 51.308(d)(1) of the Regional Haze Rule requires states with
Class I areas, i.e., downwind states, to ``establish goals (expressed
in deciviews) that provide for reasonable progress towards achieving
natural visibility conditions.'' \148\ In establishing a RPG, a
downwind state must consider the four statutory factors outlined in
Section 169A(g)(1) of the CAA--``the costs of compliance, the time
necessary for compliance, the energy and non-air quality environmental
impacts of compliance, and the remaining useful life of any potentially
affected sources.'' \149\ This requirement is commonly referred to as a
four-factor analysis. States analyze the four factors to determine a
reasonable set of control measures that will reduce visibility-
impairing emissions. The visibility improvement that will result from
these emission reductions is then factored into the state's RPGs.
---------------------------------------------------------------------------

    \148\ 40 CFR 51.308(d)(1).
    \149\ Id. 51.308(d)(1)(i)(A).
---------------------------------------------------------------------------

    In addition to conducting a four-factor analysis to determine what
control measures are reasonable for a downwind state's own sources, the
downwind state ``must consult with those States which may reasonably be
anticipated to cause or contribute to visibility impairment in the
mandatory Class I Federal area,'' \150\ i.e., upwind states. The
purpose of the consultation requirement is to ensure that the upwind
states adopt control measures sufficient to address their apportionment
of emission reductions necessary to achieve reasonable progress and
that the downwind state's RPGs properly account for the visibility
improvement that will result from the reasonable control measures
identified and included in the upwind state's long-term strategy. Where
a downwind state and an upwind state cannot agree on the proper
apportionment of emission reductions necessary to achieve reasonable
progress, however, the downwind state ``must describe in its [SIP]
submittal the actions taken to resolve the disagreement.'' \151\ This
documentation is necessary so that we have sufficient information to
evaluate the downwind state's RPGs. Ultimately, we must decide, among
other things, ``whether the State's goal provides for reasonable
progress towards natural visibility conditions,'' \152\ or whether the
goal is inadequate due to an upwind state's failure to include
reasonable control measures in its long-term strategy.
---------------------------------------------------------------------------

    \150\ Id. n 51.308(d)(1)(iv).
    \151\ Id.
    \152\ Id.
---------------------------------------------------------------------------

    Section 51.308(d)(3) of the Regional Haze Rule requires all states
(both downwind and upwind) to ``submit a long-term strategy that
addresses regional haze visibility impairment for each mandatory Class
I Federal area within the State and for each mandatory Class I Federal
area located outside the State which may be affected by emissions from
the State.'' \153\ As explained previously, a state's long-term
strategy is inextricably linked to the RPGs because it ``must include
enforceable emission limitations, compliance schedules, and other
measures as necessary to achieve the reasonable progress goals
established by states having mandatory Class I Federal areas.'' \154\
---------------------------------------------------------------------------

    \153\ Id. 51.308(d)(3).
    \154\ Id.
---------------------------------------------------------------------------

    In establishing its long-term strategy, a state must meet a number
of requirements, three of which pertain to visibility transport. First,
as a corollary to Section 51.308(d)(1)(iv), upwind states ``must
consult with [downwind] State(s) in order to develop coordinated

management strategies.'' \155\ Second, where multiple states cause or
contribute to visibility impairment in a Class I area, each state
``must demonstrate that it has included in its implementation plan all
measures necessary to obtain its share of the emission reductions
needed to meet the progress goal for the area.'' \156\ This requirement
directly addresses situations where an upwind state agrees to achieve
certain emission reductions during the consultation process, and
downwind states rely upon those reductions when setting their RPGs, but
the upwind state ultimately fails to include sufficient control
measures in its long-term strategy to ensure that the emission
reductions will be achieved. In such a situation, we must disapprove
the upwind state's long-term strategy. However, the regulations do not
explicitly address situations where the control measures in an upwind
state's long-term strategy are sufficient to obtain its share of
reductions needed to meet a RPG included in a downwind state's SIP, but
the goal itself is flawed precisely because the upwind state never
proposed sufficient control measures to ensure reasonable progress in
the first place. To prevent such situations, we interpret the term
``progress goal'' in Section 51.308(d)(3)(ii) as an approved or
approvable progress goal. Consequently, where a RPG in a downwind
state's SIP does not account for adequate visibility improvement from
an upwind state for this reason, we must disapprove both the downwind
state's goal and the upwind state's long-term strategy.
---------------------------------------------------------------------------

    \155\ Id. 51.308(d)(3)(i).
    \156\ Id. 51.308(d)(3)(ii). Similarly, ``[i]f the State has
participated in a regional planning process, the State must ensure
it has included all measures needed to achieve its apportionment of
emission reduction obligations agreed upon through that process.''
Id.
---------------------------------------------------------------------------

    Finally, each state ``must document the technical basis, including
modeling, monitoring and emissions information, on which the State is
relying to determine its apportionment of emission reduction
obligations necessary for achieving reasonable progress in each
mandatory Class I Federal area it affects.'' \157\ To reiterate,
Section 169A(g)(1) of the CAA requires states to determine ``reasonable
progress'' by considering the four statutory factors.\158\ Therefore,
this provision requires states to consider both their own Class I areas
and downwind Class I areas when they develop the technical basis
underlying their four-factor analyses. This documentation is necessary
so that the interstate consultation process can proceed on an informed
basis and so that downwind states can properly assess whether any
additional upwind emission reductions are necessary to achieve
reasonable progress at their Class I areas. The regulations further
provide that, ``States may meet this requirement by relying on
technical analyses developed by the regional planning organization and
approved by all State participants.'' \159\ Thus, states have the
option of meeting this requirement by relying on four-factor analyses
and associated technical documentation prepared by a regional planning
organization on behalf of its member states,\160\ to the extent that
such analyses and documentation were conducted. In situations where a
regional planning organization's analyses are limited, incomplete or do
not adequately assess the four factors, however, then states must fill
in any remaining gaps to meet this requirement.
---------------------------------------------------------------------------

    \157\ Id. 51.308(d)(3)(iii).
    \158\ 42 U.S.C. Section 7491(g)(1).
    \159\ 40 CFR 51.308(d)(3)(iii).
    \160\ See WildEarth Guardians v. EPA, 2014 U.S. App. LEXIS
20145, at *55 (10th Cir. Oct. 21, 2014) (explaining that 40 CFR
51.308(d)(3)(iii) ``permits a State conducting a reasonable-progress
determination'' ``to rely on [a regional planning organization's]
four-factor analysis.'').
---------------------------------------------------------------------------

    Under Auer v. Robbins, 519 U.S. 452, 461 (1997), an administrative
agency is entitled to interpret its own regulations, and that
interpretation will be entitled to judicial deference as long as the
interpretation is not ``plainly erroneous or inconsistent with the
regulation.'' \161\ Moreover, as the D.C. Circuit has explained, ``a
regulation must be interpreted as to harmonize with and further and not
to conflict with the objective of the statute it implements.'' \162\ We
believe that our clarification of the requirements of Sections
51.308(d)(1) and (d)(3), as provided above, is reasonable, consistent
with the overall framework of the Regional Haze Rule, and in harmony
with the objectives of the CAA's visibility provisions.
---------------------------------------------------------------------------

    \161\ Auer v. Robbins, 519 U.S. 452, 461 (1997).
    \162\ Sec'y of Labor, Mine Safety & Health Admin. v. W. Fuels-
Utah, 900 F.2d 318, 320 (D.C. Cir. 1990).
---------------------------------------------------------------------------

    First, we believe that our interpretation is consistent with the
Regional Haze Rule as a whole. Section 51.308(d) of the Regional Haze
Rule, which subsumes all of the provisions discussed above, provides
that states ``must address regional haze in each mandatory Class I
Federal area located within the State and in each mandatory Class I
Federal area located outside the State which may be affected by
emissions from within the State.'' \163\ Our interpretation gives this
``core requirement'' \164\ force by ensuring that downwind states
account for all reasonable emission reductions when setting their RPGs
and by ensuring that upwind states thoughtfully consider their impacts
on neighboring Class I areas when conducting their four-factor
analyses.
---------------------------------------------------------------------------

    \163\ 40 CFR 51.308(d).
    \164\ Id.
---------------------------------------------------------------------------

    Similarly, our interpretation harmonizes and furthers the goals of
the CAA. Congress declared as a national goal ``the prevention of any
future, and the remedying of any existing, impairment of visibility''
in all Class I areas.\165\ We believe it would be impossible to achieve
this goal if upwind states did not have the same responsibility to
address their visibility-impairing emissions and achieve reasonable
progress in downwind Class I areas as the downwind states themselves.
Indeed, Section 169A(b)(2) explicitly required our implementing
regulations to ``require each applicable implementation plan . . . for
a State the emissions from which may reasonably be anticipated to cause
or contribute to any impairment of visibility in any such area [i.e.,
upwind States] to contain such emission limits, schedules of compliance
and other measures as may be necessary to make reasonable progress
toward meeting the national goal.'' \166\ As explained previously, the
CAA requires states to determine what emission limits and other
measures are necessary to make reasonable progress by considering the
four statutory factors.\167\ Therefore, our interpretation of Section
51.308(d)(3)(ii) and (iii) ensures that the Regional Haze Rule requires
what the CAA requires--that upwind states consider impacts at downwind
Class I areas in their four-factor analyses and, where appropriate,
include emission limits and other measures to make reasonable progress
at those Class I areas in their long-term strategies.
---------------------------------------------------------------------------

    \165\ 42 U.S.C. Section 7491(a)(1).
    \166\ Id. Section 7491(b)(2).
    \167\ Id. Section 7491(g)(1).
---------------------------------------------------------------------------

    Moreover, consistent with our guidance,\168\ our interpretation
ensures that regional haze SIPs will be able to satisfy the CAA's
requirement that SIPs ``contain adequate provisions prohibiting . . .
any source or other type of emissions activity within the State from
emitting any air pollutant in

amounts which will interfere with measures required to be included in
the applicable implementation plan for any other State . . . to protect
visibility.'' \169\ Congress intended this provision of the CAA to
``equalize the positions of the States with respect to interstate
pollution,'' \170\ and our interpretation accomplishes this goal by
ensuring that downwind states can seek recourse from us if upwind
states are not doing enough to address visibility transport.
---------------------------------------------------------------------------

    \168\ See, e.g., Office of Air Quality Planning & Standards,
U.S. Envtl. Protection Agency, Guidance on Infrastructure State
Implementation Plan (SIP) Elements under Clean Air Act Sections
110(a)(1) and 110(a)(2) (Sept. 13, 2013).
    \169\ 42 U.S.C. 7410(a)(2)(D)(i)(II).
    \170\ S. Rep. No. 95-127, at 41 (1977).
---------------------------------------------------------------------------

    Finally, we believe that our interpretation is consistent with the
long-standing recognition of Congress, the states, the courts, and us
that regional haze is a regional problem that requires regional
solutions. In 1987, the State of Vermont first envisioned a framework
similar to the one ultimately adopted in the Regional Haze Rule by
setting a goal sufficient to ensure reasonable progress (in that case,
a summertime ambient sulfate standard) and requesting that we require
upwind states to revise their SIPs to include measures that would
provide the emission reductions necessary to meet that goal.\171\ The
Second Circuit sympathized with Vermont's plight despite upholding our
inaction on Vermont's SIP.\172\ Consequently, Congress enacted Section
169B of the CAA in 1990, which required us to issue new regulations to
address regional haze.\173\ The Congressional record indicates that
Congress was motivated in part by the dilemma of Vermont and other
downwind states.\174\ After we promulgated the Regional Haze Rule in
1999, states were acutely aware of the complexities of the visibility-
transport problem, inquiring as to how disputes regarding the proper
appropriation of emission reductions between downwind states and upwind
states would be resolved.\175\ While we encouraged early collaboration
among states in the hopes that such disputes would be minimized, we
ultimately acknowledged that we might have to step in and disapprove
either a downwind state or an upwind state's SIP because it did not
adequately address interstate visibility impacts.\176\
---------------------------------------------------------------------------

    \171\ See Vermont v. Thomas, 850 F.2d 99, 101 (2d Cir. 1988).
    \172\ Id. at 104.
    \173\ 42 U.S.C. Section 7492(e)(1).
    \174\ See, e.g., 136 Cong. Rec. 2608 (1990) (statement of Sen.
Tim Wirth); 136 Cong. Rec. 2771 (1990) (statement of Rep. Ron
Wyden); 136 Cong. Rec. 2875 (statement of Sen. Brock Adams).
    \175\ See U.S. Envtl. Protection Agency, Additional Regional
Haze Questions, 10-12 (Aug. 3, 2006).
    \176\ Id. at 12.
---------------------------------------------------------------------------

V. Our Analysis of and Proposed Action on the Texas Regional Haze SIP

    On March 31, 2009, we received a regional haze SIP revision from
Texas. Prior to receiving Texas' submittal, we reviewed a draft of the
Texas regional haze SIP and submitted comments to the TCEQ in February
2008. Many of the issues we discuss below were originally identified in
that document. This includes comments relating to ensuring that Texas
include in its SIP all measures necessary to obtain its share of the
emission reductions needed to meet the progress goals of Class I areas.
Additionally, we met with the TCEQ on July 24, 2013, to further discuss
Texas' regional haze program and impacts from Texas sources on Class I
areas. Provided below is a summary of our analysis of the various
elements of Texas' submission. For a more comprehensive analysis,
please see our TX TSD, which is located in our docket to this
rulemaking action.

A. Affected Class I Areas

    In accordance with Section 51.308(d) of the Regional Haze Rule, the
TCEQ identified two Class I areas within Texas: Big Bend National Park,
in Brewster County, which borders the Rio Grande and Mexico, and the
Guadalupe Mountains National Park in Culberson County, which borders
New Mexico. The TCEQ is responsible for developing RPGs for these two
Class I areas. The TCEQ also determined that emissions from sources in
Texas impact visibility at a number of Class I areas outside of Texas.
The Central Regional Air Planning Association (CENRAP) source
apportionment modeling results, part of the state's SIP, indicate that
Texas emissions impact the visibility at a number of Class I areas in
other states, including the Breton Wilderness Area in Louisiana, the
Great Sand Dunes in Colorado, Caney Creek and the Upper Buffalo in
Arkansas, the Wichita Mountains in Oklahoma, and several Class I areas
in New Mexico. See the TX TSD for a summary of source apportionment
modeling results for Class I areas in other states impacted by
emissions from sources in Texas.

B. Determination of Baseline, Natural, and Current Visibility
Conditions

    As required by Sections 51.308(d)(2)(i) and 51.308(d)(2)(iii) of
the Regional Haze Rule, and in accordance with our 2003 Natural
Visibility Guidance,\177\ the TCEQ calculated baseline/current \178\
and natural visibility conditions for its two Class I areas, Big Bend
and the Guadalupe Mountains, on the most impaired and least impaired
days.
---------------------------------------------------------------------------

    \177\ Guidance for Estimating Natural Visibility Conditions
Under the Regional Haze Rule, EPA-454/B-03-005, September 2003.
    \178\ Because this is the first regional haze planning period,
baseline visibility conditions and current visibility conditions are
the same. In future planning periods, we expect that baseline and
current visibility conditions will be different due to reasonable
progress being made and other changes in conditions.
---------------------------------------------------------------------------

1. Estimating Natural Visibility Conditions
    Natural background visibility, as defined in our 2003 Natural
Visibility Guidance, is estimated by calculating the expected light
extinction using default estimates of natural concentrations of fine
particle components adjusted by site-specific estimates of humidity.
This calculation uses the IMPROVE equation, which is a formula for
estimating light extinction from the estimated natural concentrations
of fine particle components (or from components measured by the IMPROVE
monitors). This equation sums the light extinction \179\ resulting from
individual pollutants, such as sulfates and nitrates. Our guidance
provides default natural conditions for the 20% worst and 20% best days
for each Class I area based on the IMPROVE equation. As documented in
our guidance, we allow states to use a ``refined'' approach or
alternative approaches to the guidance defaults to estimate the values
that characterize the natural visibility conditions of their Class I
areas. Our guidance also states that states may wish to use a more
refined approach to reduce uncertainty when baseline visibility is
already near natural conditions or when there is marked seasonality.
These alternative approaches can be implemented via alternative
estimates of natural concentrations. One alternative approach is to
develop and justify the use of alternative estimates of natural
concentrations of fine particle components. Another option open to
states is to use the ``new IMPROVE equation'' that was adopted for use
by the IMPROVE Steering Committee in December 2005.\180\ The purpose of
this

refinement to the ``old IMPROVE equation'' was to provide more accurate
estimates of the various factors that affect the calculation of light
extinction.
---------------------------------------------------------------------------

    \179\ Light extinction, in units of inverse megameters
(Mm-1), is the amount of light lost as it travels over
one million meters. The haze index, in units of deciviews (dv), is
calculated directly from the total light extinction,
bext, as follows: HI = 10 ln(bext/10).
    \180\ The IMPROVE program is a cooperative measurement effort
governed by a steering committee composed of representatives from
Federal agencies (including representatives from EPA and the federal
land managers) and regional planning organizations. The IMPROVE
monitoring program was established in 1985 to aid the creation of
Federal and State implementation plans for the protection of
visibility in Class I areas. One of the objectives of IMPROVE is to
identify chemical species and emission sources responsible for
existing anthropogenic visibility impairment. The IMPROVE program
has also been a key participant in visibility-related research,
including the advancement of monitoring instrumentation, analysis
techniques, visibility modeling, policy formulation and source
attribution field studies.
---------------------------------------------------------------------------

    The new IMPROVE equation takes into account the most recent review
of the science,\181\ and it accounts for the effect of particle size
distribution on light extinction efficiency of sulfate
(SO4), nitrate (NO3), and organic carbon. It also
adjusts the mass multiplier for organic carbon (particulate organic
matter) by increasing it from 1.4 to 1.8. New terms are added to the
equation to account for light extinction by sea salt and light
absorption by gaseous nitrogen dioxide. Site-specific values are used
for Rayleigh scattering (scattering of light due to atmospheric gases)
to account for the site-specific effects of elevation and temperature.
Separate relative humidity enhancement factors are used for small and
large size distributions of ammonium sulfate and ammonium nitrate and
for sea salt. The terms for the remaining contributors, elemental
carbon (light-absorbing carbon), fine soil, and coarse mass, do not
change between the original and new IMPROVE equations. The default
natural conditions in our 2003 guidance were updated by the Natural
Haze Levels II Committee utilizing the new IMPROVE equation and
included some refinements to the estimates for the PM
components.182 183 These estimates are referred to as the
``NCII'' default natural visibility conditions.
---------------------------------------------------------------------------

    \181\ The science behind the revised IMPROVE equation is
summarized in Appendix 5-1 of the Texas regional haze SIP and in
numerous published papers. See for example: Hand, J.L., and Malm,
W.C., 2006, Review of the IMPROVE Equation for Estimating Ambient
Light Extinction Coefficients--Final Report. March 2006. Prepared
for Interagency Monitoring of Protected Visual Environments
(IMPROVE), Colorado State University, Cooperative Institute for
Research in the Atmosphere, Fort Collins, Colorado, available at:
http://vista.cira.colostate.edu/improve/publications/GrayLit/016_IMPROVEeqReview/IMPROVEeqReview.htm and Pitchford, Marc., 2006,
Natural Haze Levels II: Application of the New IMPROVE Algorithm to
Natural Species Concentrations Estimates. Final Report of the
Natural Haze Levels II Committee to the RPO Monitoring/Data Analysis
Workgroup. September 2006, available at http://vista.cira.colostate.edu/improve/Publications/GrayLit/029_NaturalCondII/naturalhazelevelsIIreport.ppt.
    \182\ Pitchford, Marc, 2006, Natural Haze Levels II: Application
of the New IMPROVE Algorithm to Natural Species Concentrations
Estimates. Final Report of the Natural Haze Levels II Committee to
the RPO Monitoring/Data Analysis Workgroup. September 2006,
available at: http://vista.cira.colostate.edu/improve/Publications/GrayLit/029_NaturalCondII/naturalhazelevelsIIreport.ppt.
    \183\ The second version of the natural haze level II estimates
based on the work of the Natural Haze Levels II Committee is
available at: http://vista.cira.colostate.edu/Docs/IMPROVE/Aerosol/NaturalConditions/NaturalConditionsII_Format2_v2.xls.
---------------------------------------------------------------------------

    The TCEQ chose to derive a ``refined'' estimate of natural
visibility conditions rather than using the default NCII values. In
calculating natural visibility conditions, the TCEQ used the new
IMPROVE equation and PM concentration estimates (i.e., the NCII values)
for most components, but assumed that 100% of the fine soil and coarse
mass concentrations in the baseline period should be attributed to
natural causes and that the corresponding estimates in the NCII values
should be replaced. The TCEQ noted there is some uncertainty with these
calculations in the amount of natural fine and coarse mass assumption.
The TCEQ also stated that, to the extent its assumption that 100% of
coarse mass and fine soil is natural is an overestimate, it expects
that its low organic carbon estimate will more than compensate for any
errors in this assumption at this time. This issue is discussed in more
detail in our TX TSD.
    For the 20% worst days, the TCEQ calculated natural visibility
conditions for Big Bend and the Guadalupe Mountains of 10.09 dv and
12.26 dv, respectively. For the 20% best days, the TCEQ calculated that
natural visibility conditions for Big Bend and the Guadalupe Mountains
of 2.19 dv, and 2.10 dv, respectively.
    In response to FLM comments, the TCEQ also performed an additional
calculation for the 20% worst days, assuming only 80% of fine soil and
course mass as natural, in order to demonstrate the sensitivity of its
approach to this assumption. Under this approach, the TCEQ estimated
natural conditions to be 9.2 dv for the 20% worst days at Big Bend,
compared to 10.09 dv using the assumption that 100% of fine soil and
course mass is natural, and 7.16 dv using the NCII method. For the
Guadalupe Mountains, the TCEQ's estimate was 11.0 dv under the 80%
assumption, compared with 12.26 dv under the 100% assumption and 6.65
dv using the NCII method. These values are summarized below:

                                  Table 2--TCEQ Natural Visibility Calculations
----------------------------------------------------------------------------------------------------------------
                                                        Guadalupe Mountains                  Big Bend
                                                 ---------------------------------------------------------------
                                                  20% Worst days   20% Best days  20% Worst days   20% Best days
----------------------------------------------------------------------------------------------------------------
100% fine soil and coarse mass..................           12.26            2.10           10.09            2.19
80% fine soil and coarse mass...................            11.0           (\1\)             9.2           (\1\)
NCII default....................................            6.65            0.99            7.16            1.62
----------------------------------------------------------------------------------------------------------------
\1\ Not calculated.

    Ultimately, the TCEQ stated that it was including the 80%
assumption for illustration purposes only and based its calculations of
natural conditions on assuming that 100% coarse mass and fine soil
assumption are due to natural sources.
    We agree that dust storms and other blown dust from deserts are a
significant contributor to visibility impairment at the Texas Class I
areas that may not be captured accurately by our default method.
However, we propose to find that the TCEQ has not adequately
demonstrated that all coarse mass and fine soil measured in the
baseline period can be attributed to 100% natural sources.
Anthropogenic sources of coarse mass and fine soil in the baseline
period could have included emissions associated with paved and unpaved
roads, agricultural activity, and construction activities. We also note
that the impact from dust at Big Bend is less certain than at Guadalupe
Mountains and a different assumption may be appropriate in estimating
natural conditions there. Given the significant uncertainty in the
assumptions used in the Texas methodology and the demonstrated
sensitivity to the assumption of 100% natural versus 80% soil and
coarse mass

from natural sources, we propose to disapprove Texas' calculation of
the natural visibility conditions for the Big Bend and Guadalupe Class
I areas.
    In its regional haze SIP, the TCEQ stated that it will continue to
evaluate data, modeling, and any other sources of information in order
to further improve its estimates. Furthermore, the TCEQ plans to work
with us and the federal land managers to improve natural conditions
estimates for future regional haze SIP revisions. We encourage these
efforts.
    As discussed elsewhere in this notice, we propose to rely on the
NCII default values that were used for every other Class I area in the
country for our proposed FIP to address this deficiency in the Texas
regional haze SIP, but we solicit comment on the acceptability of
alternate estimates in the range between the EPA default estimates and
Texas' estimates. The federal land managers commented during the
development of the Texas regional haze SIP that an assumption of 80%
would be more reasonable than an assumption of 100%. We note that with
any of the methodologies for calculating natural conditions discussed
above, Texas' Class I areas are not projected to meet the URP in 2018
according to the CENRAP modeling and are not projected to meet the goal
of natural visibility conditions by 2064.
2. Estimating Baseline Visibility Conditions
    As required by Section 51.308(d)(2)(i) of the Regional Haze Rule,
the TCEQ calculated baseline visibility conditions for Big Bend and the
Guadalupe Mountains. The baseline condition calculation begins with the
calculation of light extinction for each day with monitoring data,
using the IMPROVE equation. As with the natural visibility conditions
calculation, the TCEQ chose to use the new IMPROVE equation, as
described above.
    The period for establishing baseline visibility conditions is 2000-
2004, and baseline conditions must be calculated using available
monitoring data, as required under Section 51.308(d)(2). The TCEQ
averaged the data from 2001 through 2004 for Big Bend \184\ and
calculated the baseline conditions at Big Bend to be 17.30 dv on the
20% worst days, and 5.78 dv on the 20% best days. In calculating the
baseline conditions at the Guadalupe Mountains, the TCEQ averaged the
visibility data for 2000-2004, and calculated the baseline conditions
at the Guadalupe Mountains to be 17.19 dv on the 20% worst days, and
5.95 dv on the 20% best days. We have reviewed the TCEQ's estimation of
baseline visibility conditions at Big Bend and the Guadalupe Mountains
and are proposing to find that the TCEQ has satisfied the requirements
of Section 51.308(d)(2)(i).
---------------------------------------------------------------------------

    \184\ The TCEQ determined that the fourth quarter of 2000 for
Big Bend was not sufficiently complete for use in calculating a
baseline average for regulatory purposes, as it had only ten
complete days.
---------------------------------------------------------------------------

3. Natural Visibility Impairment
    To address Section 51.308(d)(2)(iv)(A), the TCEQ also calculated
the number of dv by which baseline conditions exceed natural visibility
conditions for the best and worst days at Big Bend and the Guadalupe
Mountains. The natural visibility impairment is calculated by
subtracting the natural visibility calculation from the baseline
visibility calculation. This information is summarized below:

                                     Table 3--Natural Visibility Impairment
----------------------------------------------------------------------------------------------------------------
                                                                                Natural
                                              Class I area           Baseline         Natural       visibility
                                                                    visibility      visibility      impairment
----------------------------------------------------------------------------------------------------------------
20% Worst Days........................  Big Bend................           17.30           10.09            7.21
                                        Guadalupe Mts...........           17.19           12.26            4.93
20% Best Days.........................  Big Bend................            5.78            2.19            3.59
                                        Guadalupe Mts...........            5.95            2.10            3.85
----------------------------------------------------------------------------------------------------------------

    We have reviewed the TCEQ's estimates of the natural visibility
impairment at Big Bend and the Guadalupe Mountains and we propose to
disapprove these estimates because this calculation depends on the
TCEQ's calculations for natural visibility conditions, which we also
propose to disapprove for the reasons discussed in the previous
section.
4. Uniform Rate of Progress
    Under Section 51.308(d)(1)(i)(B), as part of its RPGs
determination, the TCEQ analyzed and determined the URP needed to reach
natural visibility conditions by the year 2064. Also in establishing
its RPGs, the TCEQ considered the uniform rate of improvement in
visibility and the emission reduction measures needed to achieve this
rate for the period covered by the SIP. In so doing, the TCEQ compared
the baseline visibility conditions to the natural visibility conditions
for Big Bend and the Guadalupe Mountains, and determined the URP needed
to attain natural visibility conditions by 2064. The TCEQ constructed
the URP consistent with the requirements of the Regional Haze Rule and
our 2003 Tracking Progress Guidance \185\ by plotting a straight
graphical line from the baseline level of visibility impairment to the
level of visibility conditions representing no anthropogenic impairment
in 2064 for both Big Bend and the Guadalupe Mountains.
---------------------------------------------------------------------------

    \185\ Guidance for Tracking Progress Under the Regional Haze
Rule, EPA-454/B-03-004, September 2003.
---------------------------------------------------------------------------

    Using the baseline visibility values and natural visibility values
discussed above, the TCEQ calculated the URP for Big Bend to be 0.12
dv/year, and that for the Guadalupe Mountains to be 0.08 dv/yr. This
information is summarized below:

              Table 4--Summary of Uniform Rate of Progress
------------------------------------------------------------------------
        Visibility metric              Big Bend         Guadalupe Mts.
------------------------------------------------------------------------
Baseline Conditions.............  17.30 dv..........  17.19 dv.
Natural Visibility..............  10.09 dv..........  12.26 dv.
Total Improvement by 2064.......  7.21 dv...........  4.93 dv.

Uniform Rate of Progress........  0.12 dv/year......  0.08 dv/year.
Improvement needed by 2018......  1.7 dv............  1.2 dv
------------------------------------------------------------------------

    The TCEQ notes that the URP calculations above have some degree of
uncertainty due to its assumptions in calculating the natural
visibility.
    Based on the estimated cost and visibility benefit from
NOX and SO2 controls identified during the TCEQ's
four-factor analysis described below in Section V.C.2, the TCEQ
estimated the costs and emission reduction measures of SO2
and NOX required to enable the Guadalupe Mountains and Big
Bend to achieve the URP. However, it appears that in estimating the
emission reductions and costs to meet its URPs in Table 10-9 of the
Texas Regional Haze SIP, the TCEQ used estimates of visibility benefits
from an earlier draft of the Texas Regional Haze SIP. In that draft
SIP, the TCEQ estimated the visibility benefit from a certain set of
controls to be 0.05 dv at each Texas Class I area.\186\ Based on TCEQ's
final estimation of the visibility benefit from the TCEQ control set,
we have updated the TCEQ's calculations. See our TX TSD for more
information.
---------------------------------------------------------------------------

    \186\ ``SIP Narrative comparison of changes from proposal to
adoption'' available at: http://www.tceq.texas.gov/assets/public/implementation/air/sip/haze/4HazeSIPcompare_rev.pdf
---------------------------------------------------------------------------

    Errors in its calculation aside, we note that while the TCEQ has,
in establishing its RPG, correctly followed the procedures for
analyzing and determining the rate of progress needed to attain natural
visibility conditions by the year 2064, we propose to find the TCEQ has
calculated this rate of progress on the basis of, and compared baseline
visibility conditions to, a flawed estimation of natural visibility
conditions for the Big Bend and Guadalupe Mountains, as we describe
above. Therefore, we propose to disapprove the TCEQs calculation of the
URP needed to attain natural visibility conditions by 2064. In
addition, as we discuss in Section V.C, we identify problems with the
TCEQ's reasonable progress four factor analysis, which the TCEQ
partially relied upon in consideration of the emission reduction
measures needed to achieve the natural visibility conditions. For these
reasons, we must also propose disapproval of the TCEQ's estimation of
the emission reduction measures needed to achieve the URP for the
period covered by the SIP, under Section 51.308(d)(1)(i)(B).
5. Reasonable Progress Goal Minimum
    Under Section 51.308(d)(1)(vi), Texas may not adopt a RPG that
represents less visibility improvement than is expected to result from
implementation of other requirements of the CAA during the applicable
planning period.
    The RPGs established by Texas are based on CENRAP 2018 modeling
projections. The modeling projections conducted by CENRAP contain
projections of the visibility conditions that are anticipated to be
realized at each Class I area between the 2002 base year and the 2018
future year. These projections are based on the emission reductions
resulting from federal and state control programs that are either
currently in effect or with mandated future-year emission reduction
schedules that predate 2018, including the long-term strategies of
Texas, Oklahoma, and other states, and presumptive emission reductions
expected to result from the submitted Oklahoma BART rule. Since
CENRAP's 2018 modeling projections are based on local, state, and
federal control programs that are either currently in effect or with
mandated future-year emission reduction schedules, we believe that the
TCEQ's RPGs represent at least as much visibility improvement as is
expected to result from implementation of other requirements of the CAA
(i.e., requirements other than RH) during the applicable planning
period. We therefore propose to approve Texas' submission as meeting