[Federal Register Volume 88, Number 142 (Wednesday, July 26, 2023)]
[Proposed Rules]
[Pages 48152-48179]
[FR Doc No: 2023-15338]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2014-0754; FRL-10412-01-R6]

Disapproval and Promulgation of Air Quality Implementation Plans;
Texas and Oklahoma; Regional Haze State Implementation Plans; Federal
Implementation Plan for Regional Haze; Completion of Remand

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or Act), the

Environmental Protection Agency (EPA) is proposing this action to
address the voluntary remand of portions of a final rulemaking
published in the Federal Register on January 5, 2016, addressing
regional haze obligations for the first planning period in Texas and
Oklahoma. Specifically, we are revisiting and again proposing
disapproval of portions of the Texas Regional Haze State Implementation
Plan (SIP) submission and portions of the Oklahoma Regional Haze SIP
submission that relate to reasonable progress requirements for the
first planning period from 2008 through 2018. We are also proposing to
rescind the sulfur dioxide (SO2) emission limitations we
promulgated as part of the Federal Implementation Plan (FIP) in the
January 2016 Final Rule for 15 Texas electric generating units (EGUs)
at eight facilities. We are proposing to determine that no additional
controls are required for Texas or Oklahoma sources under these States'
long-term strategies for making reasonable progress for the first
planning period. We are leaving the portions of the Texas and Oklahoma
Regional Haze SIPs that we approved in the January 2016 Final Rule in
place and not reopening those determinations in this action.

DATES:
    Comments: Comments must be received on or before September 25,
2023.
    Virtual Public hearing: The EPA will hold a virtual public hearing
to solicit comments on August 10, 2023. The last day to pre-register to
speak at the hearing will be on August 8, 2023. On August 9, 2023, the
EPA will post a general agenda for the hearing that will list pre-
registered speakers in approximate order at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal. If you require the services of a translator or a special
accommodation such as audio description/closed captioning, please pre-
register for the hearing and describe your needs by August 2, 2023.
    For more information on the virtual public hearing, see
SUPPLEMENTARY INFORMATION.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R06-
OAR-2014-0754 to the Federal eRulemaking Portal: https://www.regulations.gov/ (our preferred method). For additional submission
methods, please contact the person identified in the FOR FURTHER
INFORMATION CONTACT section.
    Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided.
    Docket: The docket for this action is available electronically at
https://www.regulations.gov/. Some information in the docket may not be
publicly available via the online docket due to docket file size
restrictions, or content (e.g., CBI). For questions about a document in
the docket please contact the individual listed in the FOR FURTHER
INFORMATION CONTACT section.
    CBI: Do not submit information containing CBI to the EPA through
https://www.regulations.gov/. To submit information claimed as CBI,
please contact the individual listed in the FOR FURTHER INFORMATION
CONTACT section. Clearly mark the part or all of the information that
you claim to be CBI. In addition to one complete version of the
comments that includes information claimed as CBI, you must submit a
copy of the comments that does not contain the information claimed as
CBI directly to the public docket through the procedures outlined in
Instructions earlier. Information not marked as CBI will be included in
the public docket and the EPA's electronic public docket without prior
notice. Information marked as CBI will not be disclosed except in
accordance with procedures set forth in 40 Code of Federal Regulations
(CFR) part 2. For the full EPA public comment policy, information about
CBI or multimedia submissions, and general guidance on making effective
comments, please visit https://www2.epa.gov/dockets/commenting-epa-dockets.
    To pre-register to attend or speak at the virtual public hearing,
please use the online registration form available at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal or contact us via email at
[email protected]. For more information on the virtual
public hearing, see SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT: Michael Feldman, Air and Radiation
Division, SO2 and Regional Haze Section (ARSH),
Environmental Protection Agency, 1201 Elm Street, Suite 500, Dallas,
Texas 75270; telephone number:<PHONE_NUMBER>; or via email:
[email protected].

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

Virtual Public Hearing

    The EPA is holding a virtual public hearing to provide interested
parties the opportunity to present data, views, or arguments concerning
the proposal. The EPA will hold a virtual public hearing to solicit
comments on August 10, 2023. The hearing will convene at 3:00 p.m.
Central Time (CT) with a 15-minute break from 5:00 to 5:15 p.m. CT. The
hearing will conclude at 7:00 p.m. CT, or 15 minutes after the last
pre-registered presenter in attendance has presented if there are no
additional presenters. The EPA will announce further details, including
information on how to register for the virtual public hearing, on the
virtual public hearing website at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal. The EPA will begin pre-registering speakers and attendees for
the hearing upon publication of this document in the Federal Register.
To pre-register to attend or speak at the virtual public hearing,
please use the online registration form available at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal or contact us via email at
[email protected]. The last day to pre-register to speak
at the hearing will be on August 8, 2023. On August 9, 2023, the EPA
will post a general agenda for the hearing that will list pre-
registered speakers in approximate order at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal. Additionally, requests to speak will be taken on the day
of the hearing as time allows.
    The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearing to run either ahead of schedule or behind schedule. Each
commenter will have approximately 3 to 5 minutes to provide oral
testimony. The EPA encourages commenters to provide the EPA with a copy
of their oral testimony electronically by including it in the
registration form or emailing it to [email protected].
The EPA may ask clarifying questions during the oral presentations but
will not respond to the presentations at that time. Written statements
and supporting information submitted during the comment period will be
considered with the same weight as oral comments and supporting
information presented at the virtual public hearing. A transcript of
the virtual public hearing, as well as

copies of oral presentations submitted to the EPA, will be included in
the docket for this action.
    The EPA is asking all hearing attendees to pre-register, even those
who do not intend to speak. The EPA will send information on how to
join the public hearing to pre-registered attendees and speakers.
    Please note that any updates made to any aspect of the hearing will
be posted online at https://www.epa.gov/tx/texas-and-oklahoma-regional-haze-sip-disapproval-and-revision-regional-haze-federal. While the EPA
expects the hearing to go forward as set forth above, please monitor
our website or contact us via email at [email protected]
to determine if there are any updates. The EPA does not intend to
publish a document in the Federal Register announcing updates.
    If you require the services of a translator or a special
accommodation such as audio description/closed captioning, please pre-
register for the hearing and describe your needs by August 2, 2023. The
EPA may not be able to arrange accommodations without advance notice.

Table of Contents

I. Executive Summary
II. Background
    A. Regional Haze
    1. Determination of Baseline, Natural, and Current Visibility
Conditions
    2. Reasonable Progress Requirements
    3. Long-Term Strategy (LTS)
    B. Previous Actions Related to Texas and Oklahoma Regional Haze
Reasonable Progress Requirements for the First Planning Period
    C. Litigation, Stay Order, and EPA's Motion for Voluntary Remand
    D. Federal Land Manager (FLM) Consultation
III. Overview of Proposed Actions
IV. Legal Authority for This Action
V. EPA's Review of the 2016 Prior Disapprovals on Remand
    A. Proposal To Incorporate Our Prior Bases for Disapprovals
    B. Supplemental Bases for Our Disapproval of Texas's Four-Factor
Analysis
    1. Selection of Sources for Evaluation in Four-Factor Analysis
    a. Texas's Cost-Effectiveness Threshold
    b. Scrubber Upgrades
    2. Consideration of the Four Factors
    a. Texas's Assumptions of SO2 Control Efficiency of
Scrubbers
    b. Texas's Cost of Compliance Analysis Assumed Future CAIR
Reductions as a Baseline
    3. Weighing of the Four Statutory Factors and Visibility
Benefits
    a. Cost of Compliance
    b. Texas's Approach in Grouping Sources
    c. Texas's Evaluation of Potential Visibility Improvements
    i. Texas's Use of Visibility Thresholds
    ii. Visibility Benefits of Texas's Estimated Control Set
    iii. Texas's Use of Degraded Background Conditions
    d. Texas's ``Order of Magnitude Estimate'' for Visibility
Improvement
    C. Clarification of Our Basis for Disapproval of Texas's
Calculation of Natural Visibility Conditions
    D. Clarification of our Basis for Disapproval of Consultation
Between Texas and Oklahoma
VI. Amending the FIP on Remand
VII. Proposed Action
VIII. Environmental Justice Considerations
IX. Impact on Areas of Indian Country
X. Statutory and Executive Order Reviews

I. Executive Summary

    The CAA's visibility protection program was created in response to
a national goal set by Congress in 1977 to remedy and prevent
visibility impairment in certain national parks, such as Big Bend, and
national wilderness areas, such as the Wichita Mountains Wilderness.
Vistas in these areas (referred to as Class I areas) are often obscured
by visibility impairment such as regional haze, which is caused by
emissions from numerous sources located over a wide geographic area.
    In response to this Congressional directive, the EPA promulgated
regulations to address visibility impairment in 1999. These
regulations, which are commonly referred to as the Regional Haze Rule
(RHR), established an iterative process for achieving Congress's
national goal by providing for multiple, approximately 10-year
``planning periods'' in which state air agencies must submit to EPA
plans that address sources of visibility-impairing pollution in their
states. The first state plans were due in 2007 for the planning period
that ended in 2018. The second state plans were due in 2021 for the
period that ends in 2028. This proposal focuses on obligations from the
first planning period of the regional haze program.
    The CAA and RHR require States to submit a long-term strategy that
includes such measures as are necessary to achieve reasonable progress
for each Class I area. A central element of the long-term strategy for
the first planning period state plans was the requirement for certain
older stationary sources to install the Best Available Retrofit
Technology (BART) for the purpose of making reasonable progress towards
Congress's national goal of eliminating visibility impairment within
our nation's most treasured lands. The other central element of a
state's long-term strategy is the requirement to include any additional
control measures that are necessary to make ``reasonable progress''
towards the national goal. To determine what control measures are
necessary to make reasonable progress and therefore must be included in
the long-term strategy, states must consider four statutory factors:
(1) the costs of compliance, (2) the time necessary for compliance, (3)
the energy and nonair quality environmental impacts of compliance, and
(4) the remaining useful life of any existing source subject to such
requirements. This statutory requirement is often referred to as a
``four-factor analysis.'' Additionally, when visibility-impairing
emissions from multiple states impact the same national park or
wilderness area, the RHR requires those states to coordinate and
consult with one another to ensure that each state is making reasonable
progress toward the national goal.
    Texas is home to numerous power plants and industrial sources, many
of which operate without modern pollution controls. As a result,
several of these plants are among the highest emitters of visibility-
impairing pollutants, such as sulfur dioxide (SO2), in the
nation. These emissions cause or contribute to visibility impairment in
such iconic places as Big Bend National Park (Big Bend) and Guadalupe
Mountains National Park (Guadalupe Mountains) in Texas, and Wichita
Mountains Wilderness Area (Wichita Mountains) in Oklahoma. To address
this visibility impairment, Texas submitted its first regional haze
state implementation plan (SIP) in 2009. After reviewing the SIP, the
EPA determined that Texas did not analyze and weigh the four statutory
factors in a reasonable way such that the SIP did not provide for
reasonable progress towards eliminating visibility-impairing pollutants
at these national parks and wilderness areas. Additionally, the EPA
determined that Oklahoma and Texas did not adequately justify why
additional reductions from Texas's sources were not necessary to
address impacts at the Wichita Mountains as part of the consultation
process required under the RHR despite information showing that impacts
from Texas's sources were several times greater than the impact from
Oklahoma's own sources. Therefore, in 2016, the EPA promulgated a final
rule disapproving these portions of Texas's SIP and Oklahoma's SIP
(while approving other aspects of both SIPs). The partial disapprovals
triggered the requirement under the CAA for the EPA to promulgate a
federal implementation plan (FIP) to remedy the deficiencies in the
SIPs. Consequently, in the same action, EPA finalized a FIP that
required

cost-effective emissions control technologies that would have resulted
in improved visibility at the Class I areas impacted by sources in
Texas. However, Texas and several industry groups filed a petition for
review challenging the final rule in the Fifth Circuit where they
obtained a stay that prevented the rule from taking effect.
    In response to the Fifth Circuit motion panel's non-binding stay
opinion, the EPA sought and received a voluntary remand of portions of
the final rule to reconsider its action. After considering the non-
binding stay opinion and other relevant facts, the EPA is again
proposing to disapprove the portions of the Texas and Oklahoma Regional
Haze SIPs that the Agency disapproved in 2016. The EPA is also
proposing to amend the FIP to account for recent developments, such as
the retirements of previously covered sources and the EPA's recently
proposed action to address the BART requirements for Texas's power
plants, which, if finalized as proposed, would reduce SO2
emissions in Texas by more than 80,000 tons per year (tpy), improving
visibility across a wide range of scenic vistas in both Texas and
nearby states. Based on these developments, the EPA proposes to
determine that no additional controls are necessary to make reasonable
progress for the first planning period, which ended in 2018.
    It has been 14 years since Texas submitted its first planning
period Regional Haze SIP to EPA for review. Since that time, the first
planning period ended, the second planning period began, and Texas
submitted its Regional Haze SIP for the second planning period. Texas
remains one of the few states in the nation that does not have a
complete first planning period regional haze plan in place to protect
the national parks and wilderness areas impacted by sources within the
state. With this action, while also taking into consideration various
power plant shutdowns in Texas and the recently proposed BART action,
the EPA is proposing to find that the requirements for the first
planning period are fulfilled. In a separate future action, EPA will
evaluate Texas's second planning period Regional Haze SIP to determine
whether that SIP satisfies the relevant statutory and regulatory
requirements.

II. 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. These sources and activities emit fine particulate
matter (PM2.5) (e.g., sulfates, nitrates, organic carbon,
elemental carbon, and soil dust) and its precursors (e.g.,
SO2, nitrogen oxides (NOX), and, in some cases,
ammonia (NH3) and volatile organic compounds (VOCs)). Fine
particle precursors react in the atmosphere to form PM2.5,
which, in addition to direct sources of PM2.5, impairs
visibility by scattering and absorbing light. Visibility impairment
(i.e., light scattering) reduces the clarity, color, and visible
distance that one can see.
    In section 169A of the 1977 Amendments to the Clean Air Act (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, anthropogenic (manmade) impairment of
visibility in 156 national parks and wilderness areas designated as
mandatory Class I areas.\1\ Congress added section 169B to the CAA in
1990 to address regional haze issues, and the EPA promulgated the
Regional Haze Rule (RHR), codified at 40 CFR 51.308,\2\ on July 1,
1999.\3\ The RHR established a requirement for all States to submit a
regional haze SIP, including the District of Columbia, and the Virgin
Islands.\4\
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    \1\ Areas designated as mandatory Class I areas consist of
National Parks exceeding 6,000 acres, wilderness areas and national
memorial parks exceeding 5,000 acres, and all international parks
that were in existence on August 7, 1977. 42 U.S.C. 7472(a). In
accordance with section 169A of the CAA, EPA, in consultation with
the Department of Interior, promulgated a list of 156 areas where
visibility is identified as an important value. 44 FR 69122
(November 30, 1979). The extent of a mandatory Class I area includes
subsequent changes in boundaries, such as park expansions. 42 U.S.C.
7472(a). Although states and tribes may designate as Class I
additional areas 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.'' 42 U.S.C. 7602(i).
When we use the term ``Class I area'' in this action, we mean a
``mandatory Class I Federal area.''
    \2\ In addition to the generally applicable regional haze
provisions at 40 CFR 51.308, EPA also promulgated regulations
specific to addressing regional haze visibility impairment in Class
I areas on the Colorado Plateau at 40 CFR 51.309. The latter
regulations are not relevant here.
    \3\ See 64 FR 35714 (July 1, 1999). On January 10, 2017, EPA
promulgated revisions to the Regional Haze Rule that apply for the
second and subsequent implementation periods. See 82 FR 3078 (Jan.
10, 2017).
    \4\ 40 CFR 51.300(b).
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    To address regional haze visibility impairment, the RHR established
an iterative planning process that requires States to periodically
submit SIP revisions (each periodic revision referred to as a
``planning period'') to address regional haze visibility impairment at
Class I areas.\5\ Under the CAA, each SIP submission must contain ``a
long-term (ten to fifteen years) strategy for making reasonable
progress toward meeting the national goal,'' and the initial round of
SIP submissions also had to address the statutory requirement that
certain older, larger sources of visibility-impairing pollutants
install and operate Best Available Retrofit Technology (BART).\6\
States' first regional haze SIPs were due by December 17, 2007, with
subsequent SIP submissions containing revised long-term strategies
originally due July 31, 2018, and every ten years thereafter.\7\ This
action addresses first planning period reasonable progress
requirements.\8\
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    \5\ See 42 U.S.C. 7491(b)(2); 40 CFR 51.308(b) and (f); see also
64 FR at 35768. EPA established in the Regional Haze Rule that all
states either have Class I areas within their borders or ``contain
sources whose emissions are reasonably anticipated to contribute to
regional haze in a Class I area;'' therefore, all states must submit
regional haze SIPs. See 64 FR at 35721. In addition to each of the
50 states, EPA also concluded that the Virgin Islands and District
of Columbia contain a Class I area and/or contain sources whose
emissions are reasonably anticipated to contribute regional haze in
a Class I area. See 40 CFR 51.300(b) and (d)(3).
    \6\ See 42 U.S.C. 7491(b)(2)(A); 40 CFR 51.308(d) and (e).
    \7\ See 40 CFR 51.308(b). The 2017 Regional Haze Rule revisions
changed the second period SIP due date from July 31, 2018, to July
31, 2021, and maintained the existing schedules for the subsequent
implementation periods. See 40 CFR 51.308(f).
    \8\ In a separate action, we proposed to withdraw the Texas
SO2 Trading Program and proposed to address the
SO2 and PM BART requirements for Texas BART eligible
sources with source-specific SO2 and PM emission limits.
See generally 88 FR 28918 (May 4, 2023).
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1. Determination of Baseline, Natural, and Current Visibility
Conditions
    The Regional Haze Rule establishes the deciview (dv) as the
principal metric for measuring visibility.\9\ This visibility metric
expresses uniform changes in the degree of haze in terms of common
increments across the entire range of visibility conditions, from
pristine to extremely hazy conditions. Visibility is also sometimes
expressed in terms of the visual range or light extinction. Visual
range is the greatest distance, in kilometers or miles, at which a dark
object can just be distinguished against the sky. Light extinction,
expressed in units of inverse megameters (Mm-1), is the
amount of light lost as it travels over distance. The haze index, in
units of deciviews (dv), is calculated directly from the total light
extinction. The deciview is a useful measure for tracking progress in
improving

visibility, because each deciview change is an equal incremental change
in visibility perceived by the human eye. Most people can detect a
change in visibility of one deciview.\10\
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    \9\ See 64 FR 35714, 35725-27 (July 1, 1999).
    \10\ The preamble to the Regional Haze Rule provides additional
details about the deciview. 64 FR at 35725.
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    The deciview is used in expressing Reasonable Progress Goals (RPGs)
(which are interim visibility goals towards meeting the national
visibility goal), defining baseline, current, and natural conditions
and tracking changes in visibility. The regional haze SIPs must contain
measures that ensure ``reasonable progress'' toward the national goal
of preventing and remedying visibility impairment in Class I areas
caused by manmade air pollution by reducing anthropogenic emissions
that cause regional haze.
    To track changes in visibility over time at each of the 156 Class I
areas covered by the visibility program (40 CFR 81.401-437), and as
part of the process for determining reasonable progress, states must
calculate the degree of existing visibility impairment at each Class I
area at the time of each regional haze SIP submittal and periodically
review progress every five years midway through each 10-year
implementation period. To do this, the RHR requirements for the first
planning period \11\ provide that states must determine the degree of
impairment (in deciviews) for the average of the 20 percent least
impaired (``best'') and 20 percent most impaired (``worst'') visibility
days over a specified time period at each of their Class I areas. In
addition, states must also develop an estimate of natural visibility
conditions for the purpose of comparing progress toward the national
goal. Natural visibility is determined by estimating the natural
concentrations of pollutants that cause visibility impairment and then
calculating total light extinction based on those estimates. We have
provided guidance to states regarding how to calculate baseline,
natural, and current visibility conditions in the first planning
period.\12\
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    \11\ The applicable requirements of the Regional Haze Rule for
the first planning period are found in 40 CFR 51.308(d).
    \12\ Guidance for Estimating Natural Visibility Conditions Under
the Regional Haze Rule, September 2003, EPA-454/B-03-005, available
at https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/20030901_oaqps_epa-454_b-03-005_estimating_natural%20_visibility_regional_haze.pdf (hereinafter
referred to as ``our 2003 Natural Visibility Guidance''); and
Guidance for Tracking Progress Under the Regional Haze Rule, EPA-
454/B-03-004, September 2003, available at https://www.epa.gov/sites/default/files/2021-03/documents/tracking.pdf (hereinafter
referred to as our ``2003 Tracking Progress Guidance'').
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    For the regional haze SIPs for the first planning period,
``baseline visibility conditions'' were the starting points for
assessing ``current'' visibility impairment. Baseline visibility
conditions represent the degree of visibility impairment for the 20
percent least impaired days and 20 percent most impaired days for each
calendar year from 2000 to 2004. Using monitoring data for 2000 through
2004, states are required to calculate the average degree of visibility
impairment for each Class I area on the 20 percent least and most
impaired days, based on the average of annual values over the five-year
period. The comparison of initial baseline visibility conditions to
natural visibility conditions indicates the amount of improvement
necessary to attain natural visibility, while the future comparison of
baseline conditions to the then current conditions will indicate the
amount of progress made. In general, the 2000-2004 baseline period is
considered the time from which improvement in visibility is measured in
the first planning period.
2. Reasonable Progress Requirements
    The vehicle for ensuring continuing progress towards achieving the
natural visibility goal is the submission of a series of regional haze
SIPs from the States that include a long-term strategy, as discussed in
the subsection that follows, and establish two RPGs (i.e., one for the
``best'' and one for the ``worst'' days) for each Class I area within
the State for each (approximately) 10-year planning period.\13\ The
Regional Haze Rule does not mandate specific milestones or rates of
progress, but instead calls for States to establish goals that provide
for ``reasonable progress'' toward achieving natural visibility
conditions. In establishing RPGs, States must provide for an
improvement in visibility for the most impaired days over the
(approximately) 10-year period of the SIP and ensure no degradation in
visibility for the least impaired days over the same period.\14\
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    \13\ See 64 FR at 35730-37.
    \14\ Id.
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    States have discretion in establishing RPGs for their Class I
areas, but in doing so must consider the following factors established
in section 169A of the CAA and in our Regional Haze Rule at 40 CFR
51.308(d)(1)(i)(A): (1) The costs of compliance; (2) the time necessary
for compliance; (3) the energy and non-air quality environmental
impacts of compliance; and (4) the remaining useful life of any
potentially affected sources. States must demonstrate in their SIPs how
they considered these four factors when establishing the RPGs for the
best and worst days for each of their Class I areas. As noted in our
Reasonable Progress Guidance for the first planning period, States have
flexibility in how they take these factors into consideration, but must
exercise that discretion in a manner consistent with the CAA and the
Regional Haze Rule.\15\ In establishing the RPGs, States must also
consider the rate of progress needed to reach natural visibility
conditions by 2064 (referred to hereafter as the ``Uniform Rate of
Progress (URP)'') and the emission reduction measures needed to achieve
that rate of progress over the 10-year period of the SIP. Uniform
progress towards achievement of natural conditions by the year 2064
represents a rate of progress, which States are to use for analytical
comparison to the amount of progress they expect to achieve. In
establishing RPGs, each State with one or more Class I areas must also
consult with potentially ``contributing states,'' i.e., other nearby
states with emission sources that may be affecting visibility
impairment at Class I areas.\16\
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    \15\ Guidance for Setting Reasonable Progress Goals under the
Regional Haze Program, June 1, 2007, memorandum from William L.
Wehrum, Acting Assistant Administrator for Air and Radiation, to EPA
Regional Administrators, EPA Regions 1-10 (pp. 4-2, 5-1).
    \16\ 40 CFR 51.308(d)(1)(iv).
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3. Long-Term Strategy (LTS)
    Consistent with the requirement in section 169A(b) of the CAA that
States include in their regional haze SIP a 10-to-15-year strategy for
making reasonable progress, section 51.308(d)(3) of the Regional Haze
Rule requires that States include a LTS that addresses regional haze
visibility impairment for each mandatory Class I area within the State
and for each mandatory Class I area located outside the State which may
be affected by emissions from the State. The LTS in each implementation
period is the compilation of all control measures a State has
determined are necessary to make reasonable progress towards achieving
natural visibility conditions. The LTS must include ``enforceable
emissions limitations, compliance schedules, and other measures as
necessary to achieve the reasonable progress goals'' for all Class I
areas within, or affected by emissions from, the state.\17\
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    \17\ 40 CFR 51.308(d)(3).
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    When a State's emissions are reasonably anticipated to cause or
contribute to visibility impairment in a Class I area located in
another State, the Regional Haze Rule requires the

impacted state to coordinate with the contributing States in order to
develop coordinated emissions management strategies.\18\ In such cases,
the contributing State must demonstrate that it has included in its SIP
submission all measures necessary to obtain its share of the emission
reductions needed to meet the RPGs for the Class I area. A State must
also consult with any State having emissions that are reasonably
anticipated to contribute to visibility impairment in any of its
mandatory Class I areas.\19\ Where other States cause or contribute to
impairment in a mandatory Class I area, the 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.\20\ The State must document the technical basis on
which the State is relying to determine its apportionment of emission
reduction obligations necessary for achieving reasonable progress in
each mandatory Class I area it affects.\21\ Regional planning
organizations (RPOs) have provided forums for significant interstate
consultation, but additional consultations between States may be
required to sufficiently address interstate visibility issues. This is
especially true where two States belong to different RPOs.
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    \18\ 40 CFR 51.308(d)(3)(i).
    \19\ 40 CFR 51.308(d)(3)(i).
    \20\ 40 CFR 51.308(d)(3)(ii).
    \21\ 40 CFR 51.308(d)(3)(iii).
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    States should consider all types of anthropogenic sources of
visibility impairment in developing their LTS, including stationary,
minor, mobile, and area sources.\22\ At a minimum, states must describe
how each of the following seven factors listed below are taken into
account in developing their LTS: (1) Emission reductions due to ongoing
air pollution control programs, including measures to address
``reasonably attributable visibility impairment'' (RAVI); (2) measures
to mitigate the impacts of construction activities; (3) emissions
limitations and schedules for compliance to achieve the RPG; (4) source
retirement and replacement schedules; (5) smoke management techniques
for agricultural and forestry management purposes including plans as
currently exist within the State for these purposes; (6) enforceability
of emissions limitations and control measures; (7) the anticipated net
effect on visibility due to projected changes in point, area, and
mobile source emissions over the period addressed by the LTS.\23\
---------------------------------------------------------------------------

    \22\ 40 CFR 51.308(d)(3)(iv).
    \23\ 40 CFR 51.308(d)(3)(v).
---------------------------------------------------------------------------

B. Previous Actions Related to Texas and Oklahoma Regional Haze
Reasonable Progress Requirements for the First Planning Period

    On March 31, 2009, Texas submitted a regional haze SIP (the 2009
Regional Haze SIP) to the EPA to address regional haze requirements for
the first planning period. On December 16, 2014, we proposed an action
to partially approve this SIP revision as meeting certain requirements
of the regional haze program (2014 Proposed Rule).\24\ We also proposed
to partially disapprove the Texas 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. Given the large visibility impairment at
Oklahoma's Class I area \25\ due to emissions from Texas and the
requirements to develop emission control strategies in consultation
with impacting States,\26\ we proposed in the same action to partially
disapprove a revision to the Oklahoma SIP submitted on February 19,
2010, which also addressed regional haze for the first planning
period.\27\ We proposed a FIP for Texas and Oklahoma to remedy the
deficiencies we identified in the SIPs.
---------------------------------------------------------------------------

    \24\ 79 FR 74818 (Dec. 16, 2014).
    \25\ Wichita Mountains is the only Class I area in Oklahoma. 40
CFR 81.424.
    \26\ 79 FR at 74821-74822.
    \27\ Specifically, we proposed to disapprove the portion of the
Oklahoma Regional Haze SIP that addresses the requirements of
section 51.308(d)(1), except for section 51.308(d)(1)(vi). 79 FR
74818 (Dec. 16, 2014).
---------------------------------------------------------------------------

    In January 2016, we took final action to partially approve and
partially disapprove portions of Texas's 2009 Regional Haze SIP and
Oklahoma's 2010 Regional Haze SIP (2016 Final Rule).\28\ We approved
the Texas SIP revision as meeting certain requirements of the regional
haze program, including BART requirements for facilities other than
Electric Generating Units (EGUs).\29\ We disapproved Texas's RPGs for
Big Bend and the Guadalupe Mountains and found that Texas did not
satisfy several of the requirements of the Regional Haze Rule at 40 CFR
51.308(d)(1) with regard to establishing RPGs, most notably the four-
factor analysis required under section 51.308(d)(1)(i)(A) and the
requirement to adequately justify RPGs that are less stringent than the
URP under section 51.308(d)(1)(ii). We disapproved Texas's calculation
of natural visibility conditions for Big Bend and Guadalupe Mountains
under section 51.308(d)(2)(iii) and other calculations that are
dependent on the calculation of natural visibility conditions,
including the calculation of the emission reductions needed to achieve
the URP for these Class I areas under section 51.308(d)(1)(i)(B) and
the calculation of the number of deciviews by which baseline conditions
exceed natural visibility conditions under section 51.308(d)(2)(iv)(A).
We also disapproved a majority of the portions of Texas's 2009 Regional
Haze SIP that address the long-term strategy requirements under section
51.308(d)(3), including the long-term strategy consultations with
Oklahoma. In the 2016 Final Rule, we also disapproved Oklahoma's RPGs
for the Wichita Mountains and disapproved the portions of the Oklahoma
SIP addressing the requirements of section 51.308(d)(1) with regard to
setting RPGs, with the exception of section 51.308(d)(1)(vi), which we
approved.
---------------------------------------------------------------------------

    \28\ 81 FR 296 (Jan. 5, 2016).
    \29\ For EGU facilities, we addressed the BART requirements in a
separate rulemaking in 2017 (and affirmed in 2020), which, in part,
created the Texas SO2 Trading Program. See 82 FR 48324
(October 17, 2017) and 85 FR 49170 (Aug.12, 2020). We recently
proposed to withdraw the Texas SO2 Trading Program and
proposed to replace the program with source-specific SO2
emission limits for BART eligible sources. See generally 88 FR 28918
(May 4, 2023). We are not addressing BART for Texas EGUs in this
proposed rule.
---------------------------------------------------------------------------

    We also finalized a FIP for Texas and Oklahoma to remedy the
deficiencies we identified in their SIPs (2016 FIP).\30\ The FIP
included our own four factor analysis for Texas and implemented
SO2 emission limits on fifteen Texas EGUs at eight different
facilities as part of a long-term strategy for making reasonable
progress at the Class I areas in Texas and Oklahoma; \31\ established
revised natural conditions on the 20 percent best and worst days for
the Guadalupe Mountains and Big Bend Class I areas; recalculated the
number of deciviews by which baseline visibility conditions exceed
natural visibility conditions for the Guadalupe Mountains and Big Bend
Class I areas; and established new RPGs for the Big Bend, the Guadalupe
Mountains, and Wichita Mountains Class I areas.\32\ The FIP did not
establish any additional requirements on sources within Oklahoma.
---------------------------------------------------------------------------

    \30\ See 81 FR at 346-47.
    \31\ The Class I areas in Texas are Big Bend and Guadalupe
Mountains. The Class I area in Oklahoma is Wichita Mountains.
    \32\ 81 FR at 346-47.

---------------------------------------------------------------------------

C. Litigation, Stay Order, and EPA's Motion for Voluntary Remand

    On March 1, 2016, the State of Texas, the Public Utility Commission
of Texas, and the Texas Commission on Environmental Quality (Texas)
filed a petition for review of the 2016 Final Rule in the United States
Court of Appeals for the Fifth Circuit. Additional parties added as
petitioners include Luminant Generation Company, L.L.C., and other
Utilities.\33\ On March 28, 2016, the Court granted motions to
intervene filed by IBEW Local Union 2337 in support of petitioners and
by Sierra Club and National Parks Conservation Association (NPCA) in
support of the EPA.\34\
---------------------------------------------------------------------------

    \33\ Other parties include: Big Brown Power Company, L.L.C.;
Luminant Mining Company, L.L.C.; Big Brown Lignite Company, L.L.C.;
Luminant Big Brown Mining Company, L.L.C.; Southwestern Public
Service Company; Utility Air Regulatory Group; Coleto Creek Power,
L.P.; NRG Texas Power, L.L.C.; and Nucor Corporation (Utilities).
    \34\ The Court combined all petitions under Case No. 16-60118.
---------------------------------------------------------------------------

    On March 3, 2016, and March 17, 2016, the Utilities and Texas
respectively filed motions to stay the 2016 Final Rule in the Fifth
Circuit. The EPA filed a response to these motions on April 7, 2016,
and the Utilities and Texas filed separate reply briefs on April 18,
2016. The motions panel rendered a non-binding opinion on July 15, 2016
(2016 stay opinion), granting the stay and concluding, in part, that
the Petitioners had demonstrated a strong likelihood of success on the
merits.\35\
---------------------------------------------------------------------------

    \35\ Texas v. EPA, 829 F.3d 405, 411 (5th Cir. 2016).
---------------------------------------------------------------------------

    Regarding the EPA's disapproval of Texas's RPGs, the motions panel
held that ``Petitioners are likely to establish that EPA improperly
failed to defer to Texas's application of the statutory factors and
improperly required a source-specific analysis not found in the Act or
Regional Haze Rule.'' \36\ As to EPA's disapproval of the consultation
between Texas and Oklahoma, the panel stated that ``EPA's disapproval
seems to stem in large part from its assertion that Texas had to
conduct a source-specific analysis and provide Oklahoma with that
source-specific analysis.'' \37\ The panel found that, ``given the
absence of a regulation or statute requiring source-specific
consultations'' (among other things), the ``Petitioners have a strong
likelihood of success in showing that EPA's disapproval of the
consultation between Oklahoma and Texas was arbitrary and capricious.''
\38\
---------------------------------------------------------------------------

    \36\ Texas, 829 F. 3d at 428. Additionally, the Court noted that
``other grounds for disapproval were asserted in the proposed rule
but were not finalized in the Final Rule.''
    \37\ Texas, 829 F. 3d at 428.
    \38\ Texas, 829 F. 3d at 429.
---------------------------------------------------------------------------

    Regarding the FIP, the panel found that Petitioners had a strong
likelihood of showing that EPA acted in excess of its statutory power
when it imposed emission controls that would not be installed until
after the period of time covered by the first planning period.\39\ The
panel found that ``EPA bound states (and accordingly bound itself) to a
ten-year window when it promulgated the Regional Haze Rule,'' and that
the EPA does not have the authority to require actions that would take
place after the particular period.\40\ Finally, the panel held that the
``EPA's truncated discussion of [electric power] grid reliability
indicates that the agency may not have fulfilled its statutory
obligation to consider the energy impacts of the FIP.'' \41\
---------------------------------------------------------------------------

    \39\ Texas, 829 F. 3d at 430.
    \40\ Texas, 829 F. 3d at 430.
    \41\ Texas, 829 F. 3d at 433. Additionally, the court stated it
did not need to consider whether EPA improperly used a dollars per
ton of reduced pollution metric versus a dollars per deciview
improvement metric ``or whether the costs imposed are unreasonable
as a whole in light of the minimal visibility benefits the FIP would
achieve in the relevant period,'' because petitioners have a strong
likelihood of establishing other flaws in the FIP. Texas, 829 F. 3d
at 431.
---------------------------------------------------------------------------

    The panel further found that petitioners had demonstrated that they
would suffer irreparable injury if the effect of the 2016 Final Rule
was not stayed pending litigation of the petition for review.\42\
Moreover, the panel found that a stay would not injure EPA or
Intervenor-Respondents, and that ``the public's interest in ready
access to affordable electricity outweighs the inconsequential
visibility differences that the federal implementation plan would
achieve in the near future.'' \43\ As such, the panel stayed the 2016
Final Rule in its entirety, ``including the emissions control
requirements, pending the outcome of this petition for review.'' \44\
---------------------------------------------------------------------------

    \42\ Texas, 829 F. 3d at 433-434.
    \43\ Texas, 829 F. 3d at 434-435.
    \44\ Texas, 829 F. 3d at 435.
---------------------------------------------------------------------------

    In addition to the panel's ruling, one of the petitioners,
Luminant, submitted a request for administrative reconsideration of the
2016 Final Rule pursuant to CAA section 307(d)(7)(B) on March 2,
2016.\45\ Among other things, Luminant argued that reconsideration is
appropriate because EPA did not finalize its proposal to rely on the
Cross-State Air Pollution Rule (CSAPR) to satisfy BART for Texas EGUs,
but nonetheless finalized the Agency's proposed long-term strategy and
RPGs for Texas. Luminant argued that, ``by deferring this action, EPA
is fundamentally changing the manner in which it will evaluate BART
controls for Texas and how reasonable progress is evaluated.'' \46\
---------------------------------------------------------------------------

    \45\ Luminant Reconsideration (Exhibit A w/Remand Motion).
    \46\ Luminant Reconsideration (Exhibit A w/Remand Motion) at 2.
---------------------------------------------------------------------------

    On December 2, 2016, the EPA filed a motion for a partial voluntary
remand of the portions of the 2016 Final Rule disapproving the Texas
and Oklahoma SIPs and imposing FIPs.\47\ We stated that our concerns
leading to our request for a voluntary remand are ``substantial and
legitimate,'' as the court's order demonstrated that the 2016 Final
Rule could be found arbitrary and capricious or contrary to law.\48\ We
also stated that it was ``appropriate to reconsider the Final Rule,
provide interested parties with a new opportunity to provide comment,
including with respect to the views expressed in the Court's Order, and
issue a new rule that takes into account the comments received on any
factual circumstances that could warrant different outcomes.'' \49\ In
response to the EPA's motion for partial voluntary remand, on March 22,
2017, the court remanded the action to the EPA.
---------------------------------------------------------------------------

    \47\ Respondent's Motion for Partial Voluntary Remand, Texas v.
EPA, Case No. 16-60118 (Dec. 2, 2016) (hereinafter referred to as
``Remand Motion'').
    \48\ Citizens Against Pellissippi Parkway Extension, Inc. v.
Mineta, 375 F.3d 412, 417 (6th Cir. 2004). Also, Remand Motion at
21.
    \49\ Remand Motion at 21.
---------------------------------------------------------------------------

    Therefore, in this proposal, the EPA is revisiting its prior
regional haze SIP disapprovals and FIPs on remand. This is more fully
described in sections V and VI. Because the EPA's motion for remand was
specific to the prior regional haze SIP disapprovals and FIPs, we are
leaving our prior approvals in place and not reopening those
determinations in this action.\50\ Additionally, while the EPA has not
acted on Luminant's administrative

petition for reconsideration, at this time, we need not take a position
on the issue Luminant raised in its petition. In the separate 2023
Texas BART action, the EPA proposed BART controls for Texas EGUs, which
we anticipate finalizing before finalizing this reasonable progress
action.\51\ Once finalized, the Texas BART action should address
Luminant's concern.
---------------------------------------------------------------------------

    \50\ The 2016 Final Rule also disapproved portions of the
following Texas SIP submittals intended to address CAA provisions
under section 110(a)(2)(D)(i)(II) that prohibit air pollutant
emissions from interfering with measures required to protect
visibility in any other state: April 4, 2008: 1997 8-hour Ozone and
1997 PM2.5 (24-hour and annual); May 1, 2008: 1997 8-hour
Ozone and 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; and May 6,
2013: 2010 1-hour SO2 National Ambient Air Quality
Standards (NAAQS). In a proposed rule published on January 4, 2017
(82 FR 912), we proposed to reconsider the basis of our prior
disapproval and re-proposed disapproval of these portions of these
Texas SIP submittals and our final disapproval was published on
October 17, 2017 (82 FR 48324, 48332). We are not further addressing
our disapproval of the interstate visibility transport portions of
these Texas SIP submittals.
    \51\ See, Revision and Promulgation of Air Quality
Implementation Plans; Texas; Regional Haze Federal Implementation
Plan; Disapproval and Need for Error Correction; Denial of
Reconsideration of Provisions Governing Alternative to Source-
Specific Best Available Retrofit Technology (BART) Determinations 88
FR 28918 (May 4, 2023), Docket No. EPA-R06-OAR-2016-0611; EPA-HQ-
OAR-2016-0598.
---------------------------------------------------------------------------

D. Federal Land Manager (FLM) Consultation

    The RHR requires that a state, or the EPA if promulgating a FIP,
consult with FLMs before adopting and submitting a required SIP or SIP
revision or a required FIP or FIP revision. Under 40 CFR 51.308(i)(2),
a state, or the EPA if promulgating a FIP, must provide an opportunity
for consultation no less than 60 days prior to holding any public
hearing or other public comment opportunity on a SIP or SIP revision,
or FIP or FIP revision, for regional haze. The EPA must include a
description of how it addressed comments provided by the FLMs when
considering a FIP or FIP revision. We consulted with the FLMs
(specifically, U.S. Fish and Wildlife Service, U.S. Forest Service, and
the National Park Service) on April 12, 2023. During the consultation
we provided an overview of our proposed actions. The FLMs signaled
general support for our proposed action and did not provide any written
comments.\52\
---------------------------------------------------------------------------

    \52\ See ``Texas Regional Haze FLM Consultation 4_12_23.xls'' in
the docket for this action.
---------------------------------------------------------------------------

III. Overview of Proposed Actions

    To address the voluntary remand, we are proposing to disapprove the
same portions of the Texas and Oklahoma SIPs we previously disapproved
in 2016. For certain portions of these disapprovals, we are
supplementing and clarifying our rationale for disapproval. For others,
we are incorporating our original bases for disapproval as detailed in
our 2014 Proposed Rule and 2016 Final Rule.
    We are proposing to supplement and clarify our disapproval of the
portions of the Texas Regional Haze SIP that address several of the
requirements at section 51.308(d)(1) related to establishing RPGs, most
notably the four-factor analysis required under section
51.308(d)(1)(i)(A) and the requirement to adequately justify RPGs that
are less stringent than the URP under section 51.308(d)(1)(ii) based on
the consideration of the four statutory factors in section
51.308(d)(1)(i)(A). Additionally, we are proposing to supplement and
clarify our disapprovals of the Texas Regional Haze SIP regarding
natural visibility conditions and proposing to supplement and clarify
our disapprovals of the consultation portions in the Regional Haze SIPs
for Texas and Oklahoma.\53\
---------------------------------------------------------------------------

    \53\ See Section 51.308(d)(2)(iii) for requirements regarding
natural visibility conditions; Sections 51.308(d)(3)(i) and
51.308(d)(1)(iv) for the consultation requirements.
---------------------------------------------------------------------------

    For the remaining portions of the Texas Regional Haze SIP that we
are proposing to disapprove, we are relying on the bases for
disapproval that were discussed in the preambles of our 2014 Proposed
Rule and 2016 Final Rule. Similarly, for those portions of the Oklahoma
Regional Haze SIP that we are proposing to disapprove, we are relying
on the bases for disapproval that were discussed in the preambles of
our 2014 Proposed Rule and 2016 Final Rule. We do not reiterate in
detail the bases for these disapprovals in this notice but rather refer
the reader to the preambles of those prior rulemakings. See section
V.A. for a detailed list of the portions of the Texas and Oklahoma
Regional Haze SIPs for which we are proposing disapproval and
incorporating our original bases for disapproval in this action.\54\
---------------------------------------------------------------------------

    \54\ See 79 FR 74818 (2014 Proposed Rule) and 81 FR 296 (2016
Final Rule).
---------------------------------------------------------------------------

    We are proposing to amend the 2016 FIP to find that no further
federal action is needed to remedy the proposed disapprovals of
portions of the Texas and Oklahoma Regional Haze SIPs. Therefore, we
are proposing to rescind the SO2 emission limits established
in the 2016 Final Rule. Our proposal to rescind the SO2
emission limitations and the associated monitoring, reporting, and
recordkeeping requirements we established in the 2016 FIP is based on
developments that occurred during the period between the 2016 Final
Rule and this proposal, including the shutdown of several of the same
units for which we promulgated emission limits in the 2016 Final Rule,
our recently proposed SO2 BART emission limits on several of
the same units for which we required controls in the 2016 Final Rule,
and the portion of the Fifth Circuit's stay opinion pertaining to the
imposition of controls beyond the end of the planning period. We also
acknowledge the EPA's ability to consider the remaining units during
our forthcoming review of Texas's Regional Haze SIP for the second
planning period. We are also proposing to find that our rescission of
the SO2 emission limitations and the associated monitoring,
reporting, and recordkeeping requirements we established in the 2016
FIP is consistent with CAA section 110(l). Specifically, we are
proposing to find that our proposed rescission of the FIP would not
interfere with any applicable requirement concerning attainment or
reasonable further progress (as defined in section 7501 of this title),
or any other applicable requirements of the CAA.

IV. Legal Authority for This Action

    The EPA has the authority to revisit its prior actions on SIPs and
FIPs on remand. As previously stated, in light of the discussion
regarding the likelihood of success on the merits set forth in the
Fifth Circuit's 2016 stay order, EPA moved for partial voluntary remand
of the SIP disapprovals and FIPs, without admitting error. The Fifth
Circuit granted the motion and remanded the action to EPA on March 22,
2017. Thus, EPA has an obligation to complete its action on remand.
    On remand, EPA is taking this action pursuant to CAA sections
110(c)(1), 110(k)(3) and 169A(b)(2). CAA section 169A(b)(2) requires
states to revise their SIPs to contain such measures as may be
necessary to make reasonable progress towards the national visibility
goal. Additionally, CAA section 110(k)(3) authorizes EPA to approve,
disapprove, or partially approve and partially disapprove a SIP or SIP
revision, and CAA section 110(c)(1) authorizes EPA to promulgate a FIP
where ``the Administrator . . . disapproves a State implementation plan
submission in whole or in part.'' EPA's authority to take such actions
under the CAA necessarily provides it the inherent authority to revisit
and amend such actions as necessary. See Trujillo v. Gen Elec. Co., 621
F.2d 1084, 1086 (10th Cir. 1980). It is well established that agencies
have inherent authority to revisit past decisions and to revise,
replace, or repeal a decision to the extent permitted by law and
supported by a reasoned explanation. FCC v. Fox Television Stations,
Inc., 556 U.S. 502, 515 (2009); Motor Vehicle Manufacturers Ass'n of
the United States, Inc. v. State Farm Mutual Automobile Insurance Co.,
463 U.S. 29, 42 (1983); see also Encino Motorcars, LLC v. Navarro, 579
U.S. 211, 221-22 (2016). Further, the Fifth Circuit granted EPA's
request for a voluntary remand and this action responds to that remand.

V. EPA's Review of the 2016 Prior Disapprovals on Remand

    In the 2016 Final Rule, we finalized our disapprovals of several
portions of the Texas and Oklahoma Regional Haze SIPs. In this action,
we are revisiting those prior disapprovals, and we are again proposing
to disapprove those portions of the SIPs and provide supplemental
rationale, where necessary, to support the proposed disapprovals.

A. Proposal To Incorporate Our Prior Bases for Disapprovals

    The specific portions of the Texas Regional Haze SIP we disapproved
in the 2016 Final Rule are:
     Section 51.308(d)(1) regarding the RPGs for the Guadalupe
Mountains and Big Bend;
     Section 51.308(d)(1)(i)(A) regarding the requirement to
conduct a four-factor analysis;
     Section 51.308(d)(1)(i)(B) regarding the requirement to
calculate the emission reduction measures needed to achieve the URP for
the Guadalupe Mountains and Big Bend for the period covered by the SIP;
     Section 51.308(d)(1)(ii) regarding the requirement to
demonstrate, based on the factors in Section 51.308(d)(1)(i)(A), that
the progress goals adopted by Texas are reasonable;
     Section 51.308(d)(2)(iii) regarding the calculation of
natural visibility conditions for the Guadalupe Mountains and Big Bend
for the most impaired and least impaired days;
     Section 51.308(d)(2)(iv) regarding the calculation of the
number of deciviews by which baseline conditions exceed natural
visibility conditions for the Guadalupe Mountains and Big Bend for the
most impaired and least impaired days;
     Section 51.308(d)(3)(i) regarding Texas's long-term
strategy consultation with Oklahoma in order to develop coordinated
emission management strategies to address visibility impacts at the
Wichita Mountains;
     Section 51.308(d)(3)(ii) regarding the requirement for
Texas to secure its share of reductions necessary to achieve the RPGs
for the Guadalupe Mountains, Big Bend, and the Wichita Mountains;
     Section 51.308(d)(3)(iii) regarding the requirement for
Texas to document the technical basis for its long-term strategy for
the Guadalupe Mountains, Big Bend, and the Wichita Mountains;
     Section 51.308(d)(3)(v)(C) regarding Texas's emission
limitations and schedules for compliance to achieve the RPGs for the
Guadalupe Mountains, Big Bend, and the Wichita Mountains;
     30 Texas Administrative Code (TAC) 116.1510(d), which was
incorporated into the Texas Regional Haze SIP and relied on the now
defunct CAIR.
    The specific portions of the Oklahoma Regional Haze SIP we
disapproved in the January 5, 2016 rulemaking are:
     Section 51.308(d)(1) regarding the RPGs for the Wichita
Mountains;
     Section 51.308(d)(1)(i)(A) regarding the requirement to
conduct a four-factor analysis;
     Section 51.308(d)(1)(i)(B) regarding the requirement to
consider the URP for the Wichita Mountains and the emission reduction
measures needed to achieve it for the period covered by the SIP;
     Section 51.308(d)(1)(ii) regarding the requirement to
demonstrate, based on the factors in Section 51.308(d)(1)(i)(A), that
the rate of progress for the SIP to attain natural conditions by 2064
is not reasonable and that the progress goal adopted by Oklahoma is
reasonable;
     Section 51.308(d)(1)(iv) regarding the requirement for
Oklahoma to consult with Texas with respect to the visibility impact of
Texas sources at the Wichita Mountains.
    Upon revisiting the 2016 disapprovals, we are again proposing to
disapprove these portions of the Texas and Oklahoma Regional Haze SIPs.
As we discuss in sections V.B--V.D, we are proposing to clarify and
supplement the basis of our proposed disapproval of certain elements of
the SIP submissions where the Fifth Circuit motion panel's 2016 stay
opinion appears to reflect a misunderstanding or disagreement with the
bases of our disapprovals. The portions for which we are proposing to
clarify and supplement the bases of our proposed disapprovals are as
follows:
     Texas's four-factor analysis required under section
51.308(d)(1)(i) and (ii);
     Texas's calculation of the natural visibility conditions
at the Guadalupe Mountains and Big Bend required under section
51.308(d)(2)(iii);
     The portion of the Texas Regional Haze SIP that is
intended to address the requirement in section 51.308(d)(3)(i) to
consult with other States with Class I areas where Texas emissions are
reasonably anticipated to contribute to visibility impairment in order
to develop coordinated emission management strategies;
     The portion of the Texas Regional Haze SIP that is
intended to address the requirement in section 51.308(d)(3)(ii) to
demonstrate that the state has included in its regional haze SIP all
measures necessary to obtain its share of the emission reductions
needed to meet the progress goal for any Class I area in another state
where its emissions cause or contribute to visibility impairment;
     The portion of the Texas Regional Haze SIP that is
intended to address the requirement in section 51.308(d)(3)(iii) to
document the technical basis on which the state is relying to determine
its apportionment of emission reduction obligations necessary for
achieving reasonable progress at the Guadalupe Mountains, Big Bend, and
the Wichita Mountains;
     The portion of the Oklahoma Regional Haze SIP that is
intended to address the requirement in section 51.308(d)(1)(iv) to
consult with those States which may reasonably be anticipated to cause
or contribute to visibility impairment in the Wichita Mountains.
    For the remaining portions of the Texas and Oklahoma Regional Haze
SIPs that we are again proposing to disapprove, the bases for our
disapproval were previously discussed in the preamble of our proposed
rule published on December 16, 2014, and the preamble of our final rule
published on January 5, 2016. We are relying on the same bases for
disapproval previously discussed in those proposed and final
rulemakings and will not repeat the rationales in this notice but
rather refer the reader to the preamble of those prior rulemakings,\55\
and we incorporate those rationales by reference in this action. Those
remaining portions we are proposing to disapprove and for which we are
incorporating our original bases for disapproval in this action are as
follows:
---------------------------------------------------------------------------

    \55\ See 79 FR 74818 (2014 Proposed Rule) and 81 FR 296 (2016
Final Rule).
---------------------------------------------------------------------------

     Texas's RPGs for the Guadalupe Mountains and Big Bend
under section 51.308(d)(1); \56\
---------------------------------------------------------------------------

    \56\ 79 FR at 74833-74843 (2014 Proposed Rule) and 81 FR 298-
299, 338, 339-343 (2016 Final Rule).
---------------------------------------------------------------------------

     Texas's calculation of the emission reductions needed to
achieve the uniform rates of progress for the Guadalupe Mountains and
Big Bend under section 51.308(d)(1)(i)(B); \57\
---------------------------------------------------------------------------

    \57\ 79 FR at 74832-74833 (2014 Proposed Rule) and 81 FR at 299
(2016 Final Rule).
---------------------------------------------------------------------------

     Texas's calculation of the number of deciviews by which
baseline conditions exceed natural conditions for the best and worst
visibility days at the Texas Class I areas under section
51.308(d)(2)(iv) given that this calculation relies on the
determination of natural visibility conditions, which we are proposing
to disapprove; \58\
---------------------------------------------------------------------------

    \58\ 79 FR at 74832 (2014 Proposed Rule) and 81 FR at 299-300
(2016 Final Rule).
---------------------------------------------------------------------------

     The portion of the Texas Regional Haze SIP intended to
address paragraph (C) of section 51.308(d)(3)(v), which is

the requirement to consider emissions limitations and schedules for
compliance to achieve the reasonable progress goals; \59\
---------------------------------------------------------------------------

    \59\ 79 FR at 74862 (2014 Proposed Rule) and 81 FR at 301 (2016
Final Rule).
---------------------------------------------------------------------------

     30 TAC 116.1510(d), which was incorporated into the Texas
Regional Haze SIP and relies on the now defunct CAIR; \60\
---------------------------------------------------------------------------

    \60\ While the EPA finalized a limited disapproval of the
regional haze SIPs submitted by Texas and thirteen other states in a
final rule published on June 7, 2012 (77 FR 33642) because these
states relied on requirements of CAIR to satisfy certain regional
haze requirements, the EPA did not specifically take action in that
final rule on Texas's BART Rules at 30 TAC section 116 that were
incorporated in the Texas Regional Haze SIP. The EPA took final
action on Texas's BART Rules at 30 TAC section 116 in the 2016 Final
Rule (81 FR at 301, 312-313, 350). See also 79 FR at 74853-74854
(2014 Proposed Rule).
---------------------------------------------------------------------------

     Oklahoma's RPGs for the Wichita Mountains under section
51.308(d)(1) and the portions of Oklahoma's Regional Haze SIP that are
intended to address the requirements of section 51.308(d)(1)(i)(A),
(i)(B), and (ii) with respect to Oklahoma's establishment of its RPGs
for the Wichita Mountains given that these portions of Oklahoma's
Regional Haze SIP relied on and were informed by the analysis and
results of Texas's reasonable progress analysis required under section
51.308(d)(1).\61\
---------------------------------------------------------------------------

    \61\ Thus, Oklahoma did not have adequate information from
Texas, nor did it request further investigation or reductions from
those sources in Texas with the greatest potential to impact
visibility in the Wichita Mountains to properly address these
requirements under section 51.308(d)(1)(i) through (v) related to
the establishment of its RPGs. See 79 FR 74818, 74864-74872 (2014
Proposed Rule) and 81 FR 302-303, 312-313, 338, 339-343 (2016 Final
Rule).
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B. Supplemental Bases for Our Disapproval of Texas's Four-Factor
Analysis

    In establishing a RPG for each of its Class I areas, Texas is
required by CAA section 169A(g)(1) and section 51.308(d)(1)(i)(A) to
``[c]onsider 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, and include a demonstration showing how these factors were
taken into consideration in selecting the goal.'' This requirement is
often referred to as the reasonable progress ``four-factor analysis.''
In addition, section 51.308(d)(1)(ii) provides that for the period of
the SIP, if a state establishes an RPG that provides for a slower rate
of improvement in visibility than the rate that would be needed to
attain natural conditions by 2064, it must demonstrate based on the
factors in section 51.308(d)(1)(i)(A) that the rate of progress for the
SIP to attain natural conditions by 2064 is not reasonable; and that
the progress goal it adopted is reasonable. This requirement under
section 51.308(d)(1)(ii) applies to Texas because its RPGs for the 20
percent worst days establish a slower rate of progress than the URP for
Big Bend and the Guadalupe Mountains.
    We provided a detailed discussion of the basis for our disapproval
of Texas's four-factor analysis in the preamble of our 2014 Proposed
Rule and provided a more abbreviated discussion of the basis for our
disapproval in the preamble of our 2016 Final Rule.\62\ However,
statements made by the Fifth Circuit motions panel in the 2016 stay
opinion appear to reflect a misunderstanding of the basis of our
disapproval of Texas's four-factor analysis. Specifically, the opinion
indicated that the EPA disapproved the Texas SIP for failing to
evaluate the four factors on a source-specific basis. The panel's
opinion stated that:
---------------------------------------------------------------------------

    \62\ 79 FR 74818, 74830-74838 and 74841-74843 (Dec. 16, 2014);
81 FR 296, 298-299, 308-311, 313-314, 318-319, 323-324, 327 (Jan. 5,
2016).

    EPA argues that it had several grounds for disapproving the
Texas and Oklahoma goals and suggests each alone provides a
sufficient basis for the disapproval. Most of these `independent'
grounds boil down to EPA's insistence that Texas should have
conducted a source-specific requirement. Other grounds for
disapproval were asserted in the proposed rule but were not
finalized in the Final Rule. Compare 79 FR at 74,842-43 (proposing
disapproval because of Texas's cost threshold, weighing of factors
for individual sources, reliance on CAIR reductions, assumptions
about efficiency of SO2 scrubbers, evaluation of
potential improvements, order of magnitude estimate, and scrubber
upgrade estimates), with 81 FR at 298-300 (finalizing disapproval
because of lack of source-specific analysis and estimation of
natural visibility conditions).\63\
---------------------------------------------------------------------------

    \63\ Texas, 829 F. 3d at 427-428.

    The panel's characterization is incorrect. First, as we discuss in
the paragraphs and subsections that follow, the basis for our
disapproval of Texas's four-factor analysis was not, and is not, tied
to the lack of a source-specific analysis. Second, our 2016 disapproval
included these other grounds for disapproval. Here, the panel refers to
a subsection of the preamble of our 2016 Final Rule where we state that
we ``present a summary of the major points of our final decision
regarding the Texas regional haze SIP. . . and those parts of the
Oklahoma regional haze SIP that we have not previously acted upon.''
\64\ Since this was intended to be a summary, this subsection of the
2016 Final Rule did not identify and discuss in detail each of the
``other grounds for disapproval'' in the same way our 2014 Proposed
Rule did. However, these ``other grounds for disapproval'' were
discussed elsewhere in our 2016 Final Rule and in our Response to
Comments document associated with that final rule, and our disapproval
was based on consideration of all those deficiencies.\65\ In this
notice, we provide our evaluation of Texas's four-factor analysis and
again identify the deficiencies with this analysis. To address concerns
raised in the 2016 stay opinion, and where appropriate, we are
presenting additional analysis of the SIP to more fully explain the
deficiencies with Texas's four-factor analysis.
---------------------------------------------------------------------------

    \64\ See 81 FR at 298.
    \65\ See for instance 81 FR at 299, footnote 11, where we
identify the lack of consideration of scrubber upgrade as part of
the basis for our disapproval. See 81 FR at 318 where we state that
Texas's cost threshold of $2,700/ton was unreasonable and point to
the 2014 proposed rule that discussed the issue in detail. See also
the Response to Comments Document (RTC) for the Texas-Oklahoma
Reasonable Progress SIP and FIP, page 857 and 909, where we discuss
Texas's reliance on CAIR reductions and assumptions about control
efficiency of SO2 scrubbers. The RTC for the Texas-
Oklahoma Reasonable Progress SIP and FIP is available in the docket
for this action at Document ID EPA-R06-OAR-2014-0754-0087.
---------------------------------------------------------------------------

    The Regional Haze Rule does not require states to conduct four-
factor analyses on a source-specific basis. CAA section 169A(b)(2)
requires states to include in their SIPs ``emission limits, schedules
of compliance and other measures as may be necessary to make reasonable
progress.'' While these emission limits must apply to individual
sources or units, CAA section 169A(g)(1) does not explicitly require
states to consider the four factors on a source-specific basis when
determining what amount of emission reductions (and corresponding
visibility improvement) constitutes ``reasonable progress.'' The EPA
has consistently interpreted the CAA to provide states with the
flexibility to conduct four-factor analyses for specific sources,
groups of sources, or even entire source categories, depending on state
policy preferences and the specific circumstances of each state. While
the CAA and the Regional Haze Rule provide states with flexibility in
evaluating the four reasonable progress factors, states must exercise
reasoned judgment when choosing which sources, groups of sources, or
source categories to analyze. Consistent with the state's obligation to
exercise reasoned judgment in its analysis, EPA's role in reviewing a
SIP is not limited to accepting at face value a state's analysis in its
own SIP submission and its

determination that it has fully satisfied the requirements of the CAA.
    Rather, Congress tasked EPA with the responsibility of ensuring
that a SIP submission satisfies the requirements of the CAA. Abundant
case law reflects an understanding that the EPA must evaluate SIP
submissions under CAA section 110(k)(2) and (3).\66\ If a SIP
submission is deficient in whole or in part, the EPA must so find, and
if not corrected, implement the relevant requirements through a FIP
under CAA section 110(c). Courts have held that EPA's ability to ensure
that a SIP submission satisfies the requirements of the CAA includes
the ability to review a state's analysis to ensure that it is
``reasonably moored to the Act's provisions and . . . based on reasoned
analysis.'' \67\ Thus, EPA's oversight role is ``more than the
ministerial task of routinely approving SIP submissions.'' \68\ If
EPA's role were otherwise, Congress would not have expressly tasked the
agency with both reviewing SIPs for completeness (CAA section
110(k)(1)(B)) and reviewing the substance of SIPs (CAA section
110(k)(2)-(4)).
---------------------------------------------------------------------------

    \66\ See e.g., Oklahoma v. EPA, 723 F.3d 1201, 1209 (10th Cir.
2013) (upholding EPA's disapproval of ``best available retrofit
technology'' (BART) SIP, noting BART ``does not differ from other
parts of the CAA--states have the ability to create SIPs, but they
are subject to EPA review''); see also Westar Energy v. EPA, 608
Fed. App'x 1, 3 (D.C. Cir. 2015) (``EPA acted well within the bounds
of its delegated authority when it disapproved of Kansas's proposed
[good neighbor] SIP.'').
    \67\ North Dakota v EPA, 730 F.3d 750, 761 (8th Cir. 2013).
    \68\ North Dakota v EPA, 730 F.3d 750, 761 (8th Cir. 2013). See
also Alaska Department of Environmental Conservation v. EPA, 540
U.S. 461, (2004) (concluding that EPA was not limited to verifying
that a BACT determination had been made, but rather EPA could
examine the substance of the BACT determination).
---------------------------------------------------------------------------

    As an initial matter, Texas followed a source-specific approach in
selecting sources for evaluation in the four-factor analysis and in
analyzing the cost of controls for individual sources, as we discussed
in the 2014 Proposed Rule.\69\ However, as stated earlier in this
section, we disapproved Texas's four-factor analysis not because Texas
did not perform its four-factor analysis on a source-specific basis,
but because the manner in which Texas analyzed and weighed the four
reasonable progress factors was flawed and unreasonable in a number of
key areas. First, Texas's overall approach in the selection of a set of
sources and controls for evaluation was unreasonable and led to
numerous potentially cost-effective controls being dismissed or
overlooked altogether. Second, in considering the costs of compliance,
which is one of the statutory factors States must consider under
section 51.308(d)(1)(i)(A), Texas made unreasonable assumptions that
resulted in the overestimation of the cost-effectiveness of controls
and a failure to assess costs of available controls for some sources.
Finally, in addressing the requirement under section 51.308(d)(1)(i)(A)
to include a demonstration showing how the statutory factors were taken
into consideration in establishing the RPGs, Texas unreasonably weighed
the costs of compliance and the visibility benefits of controls, which
resulted in unreasonable conclusions. We discuss these flaws in Texas's
four-factor analysis and its weighing of the four factors in more
detail in the subsections that follow.
---------------------------------------------------------------------------

    \69\ 79 FR at 74834-74838.
---------------------------------------------------------------------------

1. Selection of Sources for Evaluation in Four-Factor Analysis
    The Reasonable Progress Guidance for the first planning period
provides 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.\70\ The
process begins with the identification of key pollutants and sources
and/or source categories that are contributing to visibility impairment
at each Class I area.\71\ A set of sources should be reasonably
selected for the four factor analysis based on the sources and source
categories that have been identified to contribute to visibility
impairment at the applicable Class I areas. The Reasonable Progress
Guidance recommends that states ``[i]dentify the control measures and
associated emission reductions that are expected to result from
compliance with existing rules and other available measures for the
sources and source categories.'' \72\ States should then determine what
additional control measures would be reasonable based on the statutory
factors and other relevant factors for the sources and/or sources
categories that have been identified.\73\
---------------------------------------------------------------------------

    \70\ See generally ``Guidance for Setting Reasonable Progress
Goals Under the Regional Haze Program,'' dated June 1, 2007
(hereafter ``Reasonable Progress Guidance'').
    \71\ Reasonable Progress Guidance at 3-1.
    \72\ Reasonable Progress Guidance at 2-3.
    \73\ Reasonable Progress Guidance at 2-3.
---------------------------------------------------------------------------

    After identification of key pollutants and source categories, Texas
narrowed the scope of the control analysis to point sources of
NOX and SO2 and developed a list of sources and
potential controls and costs associated with those controls. It used
the control strategy analysis developed by the Central Regional Air
Planning Association (CenRAP) as the starting point for this
analysis.\74\ Texas also included additional sources from source types
not included in the CenRAP dataset. This work resulted in a list of
sources and potential controls for reducing SO2 and
NOX, an estimate of the costs associated with each control,
and identification of the Area of Influences (AOIs) for each Class I
area.
---------------------------------------------------------------------------

    \74\ The Central States Air Resource Agencies (CenSARA) is a
regional planning organization (RPO) that was created in 1995 and
currently includes as members the states of Texas, Oklahoma,
Louisiana, Arkansas, Missouri, Kansas, Nebraska, and Iowa, as well
as the federally recognized tribes within the boundaries of these
states. CenSARA created CenRAP to coordinate activities associated
with the management of regional haze issues within the member states
and tribes. However, CenRAP has since been abolished and CenSARA
currently conducts regional haze and other air quality planning
activities for the CenSARA states.
---------------------------------------------------------------------------

    However, in selecting sources for the four-factor analysis, Texas
began by eliminating certain sources purely on the basis of cost before
the four statutory factors and the visibility benefit of controls were
considered and weighed. Moreover, Texas failed to evaluate potentially
cost-effective scrubber upgrades for sources with existing scrubbers
despite the potential for large emission reductions and visibility
benefits. Texas's overall approach in the selection of a set of sources
and controls for evaluation was unreasonable, which led to numerous
potentially cost-effective controls being dismissed or overlooked
altogether. This led to the selection of a control set that was not
appropriately refined, targeted, or focused on those sources that have
been identified as contributing to visibility impairment and have cost-
effective controls that could result in potentially significant
visibility benefits at the Class I areas impacted by Texas sources.
a. Texas's Cost-Effectiveness Threshold
    Texas's approach in establishing and applying a cost-threshold was
unreasonable. Given the multitude of sources located within the State
with the potential to impact visibility, Texas narrowed down its list
of potential sources for which to conduct a four-factor analysis. While
we agree that it is appropriate for a State to narrow down the list of
sources for which to conduct a four-factor analysis, a State's
rationale in so doing must be reasonable. When selecting the sources to
conduct a four-factor analysis, Texas unreasonably eliminated sources
for which the cost of controls exceeded $2,700/ton. Texas's use of a
$2,700/ton threshold was unreasonable for several reasons including its
reliance on the Clean Air

Interstate Rule (CAIR) as a justification, its failure to consider the
four factors or take into consideration contributions to visibility
impairment in setting the threshold, and its failure to consider the
range of costs found reasonable by CenRAP. We discuss these points in
turn in the following paragraphs.
    Texas used the analysis of potential cost of controls developed by
CenRAP as the starting point for the selection of sources to evaluate
in the four-factor analysis. CenRAP contracted with Alpine Geophysics
to conduct an evaluation of possible additional point-source add-on
controls for sources in CenRAP states with a Q/d >5.\75\ Alpine
Geophysics prepared cost estimates for potential add-on controls for
NOX and SO2 reductions in 2005 dollars for point
sources in CenRAP states using AirControlNET,\76\ a database tool the
EPA released in 2006 to enable cost-benefit analyses of potential
emissions control measures and strategies. To narrow the list of
potential controls and sources, Texas eliminated controls with an
estimated cost-efficiency greater than $2,700/ton from any further
analysis and did so regardless of their potential visibility benefits.
Texas's justification for the selection of this value was a reference
to the fact that the cost associated with implementing CAIR was up to
$2,700/ton.\77\ However, EPA promulgated CAIR to address an entirely
different issue--the interstate transport of emissions from states that
contributed to unhealthy levels of ozone and particulate matter in
certain downwind states.\78\ The interstate transport program under CAA
section 110(a)(2)(D)(i)(I) is an entirely separate program from
regional haze, serving a different statutory purpose and involving the
consideration of a different set of factors.\79\ Thus, the costs
associated with CAIR were not developed with consideration of the four
statutory factors used to determine reasonable progress, or visibility
impairment in general, and therefore, shouldn't be relied upon to
eliminate sources from evaluation for potential visibility benefits. To
the extent a state relied on a cost threshold as part of its reasonable
progress analysis, such a cost threshold must be justified in a manner
consistent with the CAA's expressly stated goal of addressing sources
of visibility impairment to Class I areas.\80\ Because Texas's SIP
justified its selection of $2,700/ton by referencing costs associated
with a program developed to address issues unrelated to regional haze,
it failed to adequately justify why such a threshold is reasonable in
the context of addressing sources of visibility impairment to Class I
areas in Texas.
---------------------------------------------------------------------------

    \75\ Q/d is the ratio of annual emissions of a given pollutant
over distance to a Class I area and can be used to identify those
sources with the largest potential to impact visibility.
    \76\ Lists of NOX and SO2 controls meeting
cost thresholds ranging from $1,500/ton to $10,000/ton developed by
Alpine Geophysics are available in the docket for this action (See
spreadsheets titled ``nox_cost_ton__2_'' and ``so2_cost_ton'') under
Document ID EPA-R06-OAR-2014-0754-0013, Attachments 11 and 13.
    \77\ See Texas Regional Haze SIP at 10-7. The SIP submittal is
available in the docket for this action under Document ID EPA-R06-
OAR-2014-0754-0002.
    \78\ See generally 70 FR 25161 (May 12, 2005).
    \79\ While CAIR, and its predecessor CSAPR, were evaluated for
BART alternatives under 40 CFR 51.308(e)(2), they were not designed
to address visibility impairment caused by regional haze.
Furthermore, the evaluation of CAIR and CSAPR as a BART alternative
did not consider costs or cost thresholds.
    \80\ See, e.g., North Dakota v. EPA, 730 F.3d 750, 766 (8th Cir.
2013).
---------------------------------------------------------------------------

    Texas's application of the $2,700/ton cost threshold unreasonably
eliminated sources from consideration without evaluating the statutory
factors or taking into consideration whether requiring controls on
those sources could result in meaningful visibility improvement in
Class I areas. In the Texas Regional Haze SIP, the State's use of a
$2,700/ton threshold resulted in the state unreasonably overlooking
potentially cost-effective controls that would have had a meaningful
visibility improvement at the affected Class I areas. Given the large
number of Texas sources and their large geographic distribution,
Texas's failure to consider location and emissions data in applying a
cost threshold to eliminate controls from further analysis was
unreasonable. This is especially true for Texas, as its two Class I
areas (Guadalupe Mountains National Park and Big Bend National Park)
are located in far West Texas. In applying the $2,700/ton threshold,
Texas screened out all EGUs (the largest point sources) in West Texas
from consideration in a four-factor analysis. These EGUs in West Texas
also impact visibility in the Class I areas located in eastern New
Mexico (Salt Creek Wilderness Area, Carlsbad Caverns National Park,
White Mountain Wilderness Area, and Pecos Wilderness Area) and the
Class I area in Oklahoma (Wichita Mountains Wilderness Area). For
example, potential SO2 controls for the Tolk Station located
in West Texas were estimated in the Alpine Geophysics analysis to cost
an average of approximately $3,100/ton and result in nearly 20,000 tpy
reduced across the two units.\81\ The Tolk facility is located
northwest of Lubbock and is in relatively close proximity to Class I
areas in Texas, New Mexico, and Oklahoma.\82\ The Tolk units were found
in the Alpine Geophysics analysis to each have a high Q/d \83\ for
SO2 at multiple Class I areas,\84\ in particular at the
Guadalupe Mountains in Texas where the Q/d is 34.4 for Unit 171B and
31.4 for Unit 172B.
---------------------------------------------------------------------------

    \81\ Lists of SO2 controls meeting cost thresholds
ranging from $1,500/ton to $10,000/ton developed by Alpine
Geophysics are available in the docket to this action (See
spreadsheet titled ``so2_cost_ton'') under Document ID EPA-R06-OAR-
2014-0754-0013, Attachment 13.
    \82\ The Tolk facility is located approximately 546 km from Big
Bend (Texas), approximately 320 km from the Guadalupe Mountains
(Texas), approximately 178 km from Salt Creek (New Mexico),
approximately 277 km from the Carlsbad Caverns (New Mexico),
approximately 298 km from the White Mountains (New Mexico),
approximately 309 km from the Pecos Wilderness (New Mexico), and
approximately 354 km from the Wichita Mountains (Oklahoma).
    \83\ Texas identified sources as ``high priority'' if they had
an emissions over distance equal to or greater than five (Q/d >= 5)
for one or more Class I areas. See Texas Regional Haze SIP at 4-3
and 10-7.
    \84\ Based on the Alpine Geophysics Analysis, the Q/d for
SO2 for the Tolk units is 32 for Unit 171B and 29.1 for
Unit 172B at the Wichita Mountains in Oklahoma; 21.1 for Unit 171B
and 19.2 for Unit 172B at Big Bend in Texas; 34.4 for Unit 171B and
31.4 for Unit 172B at the Guadalupe Mountains in Texas; and 14.9 for
Unit 171B and 13.5 for Unit 172B at Caney Creek in Arkansas.
---------------------------------------------------------------------------

    Beyond prematurely eliminating EGUs in West Texas, Texas's use of
the $2,700/ton threshold also unreasonably eliminated potentially cost-
effective SO2 controls for other sources located in close
proximity to Arkansas and Oklahoma Class I areas with a high
SO2 Q/d. This includes the Welsh Power Plant Unit 1,\85\
which was found in the Alpine Geophysics analysis to have a Q/d of 69.6
at Caney Creek and 34.2 at Upper Buffalo in Arkansas, 29.1 at the
Wichita Mountains in Oklahoma, and 27.1 at Hercules Glades in Missouri.
SO2 wet scrubber controls for Welsh Unit 1 were estimated to
cost $2,852/ton and anticipated to result in approximately 10,500 tpy
reduced. As a result of the application of this $2,700/ton threshold,
potentially cost-effective controls were not evaluated at these and
other sources that may result in meaningful visibility benefits at
Texas's own Class I areas and Class I areas in surrounding states.
---------------------------------------------------------------------------

    \85\ The Welsh facility is located approximately 161 km from
Caney Creek and 332 km from Upper Buffalo (Arkansas) and
approximately 400 km from Wichita Mountains (Oklahoma).
---------------------------------------------------------------------------

    Finally, we note that CenRAP conducted a sensitivity analysis which
evaluated controls for sources with a Q/d>5 and cost-effectiveness up
to $10,000/ton. Based on that analysis, CenRAP suggested that a range
from $4,000 to $5,000/ton would be a reasonable threshold for controls

because of diminishing emission reductions as costs increase beyond
that range.\86\ While Texas otherwise relied heavily on analyses
performed by CenRAP, it is unclear from Texas's submission why it then
opted not to consider CenRAP's analysis when selecting their $2,700/ton
cost threshold, nor did Texas consider the specific impact of how their
selected threshold may have prematurely eliminated sources with
potential cost-effective and large visibility benefits.
---------------------------------------------------------------------------

    \86\ See ``Sensitivity Run Specifications for CenRAP
Consultation,'' available in the docket for this action under
Document ID EPA-R06-OAR-2014-0754-0013. See also
``so2_cost_ton.xls'' and ``nox_cost_ton_2_.xls,'' also available in
the docket for this action under Document ID EPA-R06-OAR-2014-0754-
0013.
---------------------------------------------------------------------------

b. Scrubber Upgrades
    The EPA's guidance for setting reasonable progress goals instructs
that States should focus on those sources that may have the greatest
impact on visibility at Class I areas. This is consistent with the
national goal established by Congress of remedying any existing
impairment of visibility in Class I areas due to manmade air pollution.
As part of its source selection, Texas also failed to consider
evaluating EGUs with existing SO2 scrubbers for potential
SO2 reductions in the four-factor analysis. Such failure to
consider these sources in the four-factor analysis was unreasonable
given the large projected emissions as shown in Table 1.

                                              Table 1--SO2 Emissions at Texas EGUs With Existing Scrubbers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                SO2 emissions (tpy) *
                                                             CAMD/NEEDS/EIA verified      Scrubber     Scrubber   --------------------------------------
            Facility name                   Unit ID                 scrubber            online year     bypass                  2018 CenRAP
                                                                                2002      projection     Change
--------------------------------------------------------------------------------------------------------------------------------------------------------
Oklaunion Power.....................  1                   Wet Scrubber................         1986            Y         3,751        7,101        3,350
Limestone...........................  LIM1                Wet Scrubber................         1985            Y        16,293       12,715       -3,578
Limestone...........................  LIM2                Wet Scrubber................         1986            Y        12,974        4,983       -7,991
W.A. Parish.........................  WAP8                Wet Scrubber................         1982            Y         3,948        4,512          564
Martin Lake.........................  1                   Wet Scrubber................         1977            Y        24,832       11,351      -13,481
Martin Lake.........................  2                   Wet Scrubber................         1978            Y        22,538       11,984      -10,554
Martin Lake.........................  3                   Wet Scrubber................         1979            Y        19,024       12,396       -6,628
Monticello..........................  3                   Wet Scrubber................         1978            Y        22,889       11,882      -11,007
San Miguel..........................  SM-1                Wet Scrubber................         1982            Y        13,167        6,550       -6,617
H.W. Pirkey Power...................  1                   Wet Scrubber................         1985            Y        19,476       19,478            2
Sandow..............................  4                   Wet Scrubber................         1981            Y        23,305        8,409      -14,896
Gibbons Creek.......................  1                   Wet Scrubber................         1983            Y        10,816        2,652       -8,164
                                                                                --------------------------------------
    Total...........................                                                                                193,013      114,013      -79,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Emissions data from Texas Regional Haze SIP, Appendix 10.4b.

    We note that the AirControlNET database does not include general
information for the cost and effectiveness of scrubber upgrades as the
cost and reductions from these potential upgrades are typically very
specific to the existing equipment and site-specific conditions. The
cost of scrubber upgrades at coal-fired power plants has been evaluated
in many other instances in both the context of BART and reasonable
progress for both the first and second planning periods for regional
haze. Based on what we have seen in other regional haze actions,
upgrading an underperforming SO2 scrubber is generally very
cost-effective.\87\ At the time Texas conducted its analysis, many EGUs
were equipped with older vintage scrubbers and/or had scrubber bypasses
that divert a portion of the exhaust gas around the control equipment.
In some cases, excess scrubbing capacity is simply not being utilized.
Texas included many of these types of sources in the maps showing AOIs
and ``high priority'' sources for other state's Class I areas, as well
as in the table of sources within the Class I areas AOI, in their
correspondence with other states (see Appendix 4.2 of the Texas
Regional Haze SIP). However, Texas omitted these sources from their
source selection of SO2 point sources and thus did not
consider them as part of the four-factor analysis without providing a
reasonable justification.
---------------------------------------------------------------------------

    \87\ See, for instance, the North Dakota Regional Haze SIP:
scrubber upgrades for the Milton R. Young Station Unit 2 were
evaluated under BART and were found to cost $522/ton and scrubber
upgrades with coal drying for the Coal Creek Station Units 1 and 2
were evaluated under BART and found to cost $555/ton at each unit.
See the EPA's final action approving the SO2 BART
determinations for the Coal Creek Station Units 1 and 2 and for the
Milton R. Young Station Unit 2 at 77 FR 20894 (April 6, 2012). See
also the Wyoming Regional Haze SIP: scrubber upgrades for Wyodak
Unit 1 were evaluated to address the RHR requirements under 40 CFR
51.309 and found to cost $1,167/ton. The EPA approved this portion
of the Wyoming Regional Haze SIP at 77 FR 73926 (December 12, 2012).
---------------------------------------------------------------------------

    Furthermore, even with these existing SO2 controls, some
of these EGUs are still among the largest SO2 emitting
sources in the State and have large Q/ds. For example, the Martin Lake
facility had a Q/d for Guadalupe Mountains (958 km away) greater than
37 using the projected 2018 SO2 emissions. Emissions at
Martin Lake unit 1 in the CenRAP emission inventory were projected to
decrease from 24,832 tpy in 2002 to 11,351 tpy in 2018. This is because
the 2018 projected emissions include predicted emission reductions due
to CAIR at many of these controlled facilities, suggesting some
increase in control efficiency, decreased bypass, and/or burning fuels
with a lower average sulfur content is already included in the 2018
projections. Thus, even starting with this conservatively lower figure,
upgrading the existing scrubber to 95 percent control efficiency would
result in an approximate emission reduction of an additional 7,000 tpy
beyond those reductions that were projected to occur due to CAIR.\88\
Scrubber upgrades across all three Martin Lake units could result in
emission reductions of approximately 21,000 tpy beyond the level of
control assumed in the 2018 projections. The EGUs Texas omitted from
consideration in its four-factor analysis represent approximately one-
third of the total

projected Texas EGU SO2 emissions in 2018.\89\ This is a
significant fraction of Texas EGU emissions that were not analyzed for
potential emission reductions without a reasonable justification.
Additionally, SO2 scrubber upgrade controls are typically
very cost-effective. This is because a scrubber can be upgraded by
reusing as many structural components and equipment in the existing
unit as possible, such as existing structural steel and absorber
shells, ducts, pumps, and compressors. A scrubber can be upgraded by
applying new scrubbing technology to improve its removal efficiency,
decrease operating costs, and improve operations and reliability for
much less than it would cost to replace it with a new scrubber. In some
cases, the overall removal efficiency of an existing scrubber can be
increased by simply decreasing or eliminating the amount of emissions
that bypass the scrubber \90\ and/or increasing the amount of reagent
used in the scrubber, which are relatively inexpensive ways to improve
the removal efficiency of a scrubber compared to installing a new
scrubber. Given the projected emissions of the sources shown in Table
1, the size of the impact from Texas emissions, and the source
apportionment data indicating the large impact from SO2
emissions from EGUs, we propose to find it was unreasonable for Texas
to not perform any analysis on these sources or at least request
additional information from the facilities concerning potential
scrubber upgrades.
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    \88\ Based on EPA Clean Air Markets Division (CAMD) annual
SO2 emissions data and U.S. Energy Information
Administration (EIA) data on reported sulfur content and tonnages of
the fuels burned at Martin Lake Unit 1 in 2009-2013, scrubber
upgrades achieving SO2 removal efficiency of 95 percent
are estimated to reduce SO2 emissions to 3,706 tpy. The
difference between the CenRAP 2018 projected SO2
emissions for Martin Lake Unit 1 (11,351 tpy) and the estimated
SO2 emissions resulting from scrubber upgrades (3,706
tpy) is 7,645 tpy. See the Excel file ``Coal vs CEM data 2009-
2013.xlsx,'' ``charts'' tab, cell ``N15'' found in our docket under
Document ID EPA-R06-OAR-2014-0754-0007, Attachment 17.
    \89\ See Texas Regional Haze SIP, Appendix 10.4b.
    \90\ Ways in which scrubber bypass can be decreased or
eliminated include adding fan capacity, upgrading the electrical
distribution system, and conversion to a wet stack.
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2. Consideration of the Four Factors
    As stated previously, in establishing a RPG for each Class I area
located within the state, Texas is required by CAA section 169A(g)(1)
and section 51.308(d)(1)(i)(A) to ``[c]onsider 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, and include a demonstration showing
how these factors were taken into consideration in selecting the
goal.'' This requirement is often referred to as the reasonable
progress four-factor analysis. In considering the costs of compliance,
Texas made unreasonable assumptions that resulted in the overestimation
of the cost-effectiveness of controls and a failure to assess costs of
available controls.
a. Texas's Assumptions of SO2 Control Efficiency of
Scrubbers
    Pursuant to CAA section 169A(g)(1) and section 51.308(d)(1)(i)(A),
States must consider the costs of compliance. Texas's assumptions of
the control efficiency of controls led to an overestimation of the cost
of scrubber retrofits. The control efficiency of new scrubbers
evaluated by CenRAP and Texas, based on the data from AirControlNET,
was assumed to be 90 percent. SO2 scrubber retrofits are
capable of achieving emission reductions of at least 95 percent for dry
scrubbers and 98 percent for wet scrubbers.\91\ Texas's assumption of
90 percent control efficiency materially affected its analysis due to
the large visibility impact of Texas point sources, and EGUs in
particular. For instance, the difference in emission reductions
assuming 90 percent control efficiency compared to 98 percent is 1,851
tons for Unit 1 and 1,891 tons for Unit 2 at Big Brown. These
additional reductions would have further reduced the estimated costs of
the controls to approximately $1,400/ton and increased the visibility
benefit anticipated due to controls. At Monticello Units 1 and 2, the
higher control efficiency would have resulted in an additional 1,500
tons reduced at a cost of $1,700/ton. Assuming 98 percent control
efficiency compared to 90 percent control efficiency at all the EGUs
Texas evaluated in the four-factor analysis would have resulted in an
additional 9,800 tons reduced. Therefore, Texas's assumptions of the
emission reductions due to controls and their consideration of cost led
to an overestimation of the costs of controls.\92\
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    \91\ See the Oklahoma Regional Haze FIP at 76 FR 81728, 81742
(Dec. 28, 2011).
    \92\ Underestimation of emission reductions also resulted in an
underestimation of the visibility benefits.
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b. Texas's Cost of Compliance Analysis Assumed Future CAIR Reductions
as a Baseline
    Texas failed to consider how reliance on the 2018 emission
projections under CAIR impacted their source selection, estimated costs
of controls, and estimated visibility benefits of controls. A critical
decision point in performing the cost analysis for potential controls
is the determination of an emission baseline. Texas and CenRAP relied
on the IPM predictions to estimate 2018 emission levels for EGUs. Texas
identified that the majority of the emission reductions underlying the
predicted visibility improvements in 2018 resulting from controls
already in effect or scheduled to become effective will result from the
CAIR program in particular. The Integrated Planning Model (IPM)
analysis used by CenRAP predicted that due to CAIR compliance, by 2018,
EGUs in Texas would purchase approximately 125,000 tpy of emissions
allowances from out of state.\93\ IPM predicted that many EGUs in Texas
would reduce their emissions either through changes in coal, increased
efficiency of existing controls, or installation of new controls. Texas
also noted that there is uncertainty in the size and distribution in
emissions in the future projections and that no EGUs made an
enforceable commitment to any particular pollution control strategy and
preferred to retain the flexibility offered by the CAIR program.\94\
The CAIR program allows interstate trading of allowances and does not
put specific emission limits on specific sources. Texas notes that
because emission allowances can be purchased by EGUs, visibility
improvement may be less or more that that predicted by the CenRAP's
modeling. Nevertheless, Texas unreasonably utilized this future
projection of 2018 emissions as the starting point for its estimation
of emission reductions and the associated costs of additional controls
in its four-factor analysis.\95\ Although we acknowledge that CAIR is
now defunct and has been replaced by CSAPR, Texas presumed that those
results would be comparable under any program to replace CAIR.
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    \93\ CenRAP used the IPM (Version 2.19) that the EPA employed to
predict the emissions reductions expected from CAIR in 2018 and
Texas used the CenRAP analysis as their starting point in the four-
factor analysis. The IPM model predicts the effect of emission
trading programs considering economics, logistics, and the specific
regulatory environment for each EGU. The EPA released the results
and documentation for the IPM Version 2.19 in 2005.
    \94\ See Texas Regional Haze SIP at section 10.5.
    \95\ See Texas Regional Haze SIP at 10-7, 10-8, and 10-9. While
Texas relied on CAIR to satisfy the BART requirements for EGUs, BART
is only one component of a long-term strategy to make reasonable
progress for the first regional haze planing period. A state should
look beyond BART for additional reductions when assessing reasonable
progress.
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    The 2018 emission projections under CAIR that Texas relied on for
source selection assumed that sources such as W. A. Parish Units WAP5,
WAP6, and WAP7 and Welsh Units 2 and 3 would install SO2
controls to significantly reduce their annual SO2 emissions
by 2018. However, it was unreasonable for Texas to rely on these
projected CAIR reductions for the baseline in their analysis because
there were no enforceable requirements to accompany these
SO2 reductions. In assuming the

2018 emission projections under CAIR as the baseline in their analysis,
Texas assumed a starting point where scrubbers were already installed
and the only potential control measure considered for these units was
to ``repower'' at an extremely high cost that far exceeded the $2,700/
ton threshold Texas applied, leading Texas to omit the W. A. Parish and
Welsh units from their selection of sources to evaluate in the four-
factor analysis. However, similar to Big Brown and Monticello,
scrubbers were likely cost-effective for these units and should have
been considered for the units at Parish and Welsh. As shown in Table 2,
the emission baseline Texas used assumed that SO2 emission
reductions under CAIR would be 45,447 tpy across the three W. A. Parish
units (approximately 80 percent reduction) and 21,129 tpy across the
two Welsh units (approximately 90 percent reduction). It was
unreasonable for Texas to omit consideration of scrubbers for Welsh and
Parish units simply because the 2018 emission projections used as their
baseline assumed scrubbers would already be in place in 2018 due to
CAIR. The use of this baseline resulted in large sources being left out
of the control set Texas evaluated in their four-factor analysis even
though the emission reductions were not enforceable and were based on
SO2 controls that have never been installed. In its SIP,
Texas even acknowledged the uncertainties in its 2018 emissions
projections by its in depth review of an updated emission projection,
available at the time Texas was developing its SIP revision, that did
not predict scrubber upgrades or large emission reductions at the
Parish and Welsh Units.\96\ This highlights the uncertainty of
projections for specific units and the sensitivity of emission
projections to inputs in the projections, for instance, higher natural
gas prices. Texas should have recognized the flexibility in the CAIR
trading program and the resulting uncertainty in the projected
emissions and projected controls. In other words, it was unreasonable
for Texas to rely on unenforceable projected controls, and not to have
recognized that implementation of reasonable controls under the
Regional Haze Rule would likely not be in addition to anticipated
reductions due to CAIR predicted by IPM but would replace or complement
any controls predicted by IPM.
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    \96\ The 2018 emission projections Texas used as its baseline
were based on the Integrated Planning Model (IPM) Version 2.19;
however, there was also an updated version of IPM available for
review at the time Texas was developing its SIP (Version 3.0). Texas
provided an in-depth comparison of the two IPM runs in Appendix 7-2
of their SIP submittal. While the IPM 3.0 results estimated very
similar overall SO2 emissions, IPM 3.0 estimated larger
reductions at Big Brown and Monticello and did not predict scrubber
installations or large emission reductions at the Parish and Welsh
units. See Texas Regional Haze SIP, at pg. 10-9 and Appendix 7-2, at
pg. 8.
    \97\ We note that the difference in projected emissions for W.A.
Parish facility between IPM Versions 2.19 and 3.0 is 29,407 tons,
and the difference in projected emissions for the Welsh facility is
21,354 tons. See Texas Regional Haze SIP, Appendix 7-2, at pg.8.

                  Table 2--2002 SO2 Emissions vs. 2018 Projected SO2 Emissions Under CAIR \97\
----------------------------------------------------------------------------------------------------------------
                                                                                2018 SO2
                                                               2002 SO2         emissions        Projected SO2
          Facility name                    Unit ID             emissions    projections under      emissions
                                                                (tpy) *        CAIR (Texas      reductions under
                                                                            baseline) (tpy) *      CAIR (tpy)
----------------------------------------------------------------------------------------------------------------
W.A. Parish......................  WAP5                             20,523              3,733             16,790
W.A. Parish......................  WAP6                             17,863              3,809             14,054
W.A. Parish......................  WAP7                             17,900              3,297             14,603
Welsh............................  2                                11,995              1,223             10,772
Welsh............................  3                                11,584              1,227             10,357
----------------------------------------------------------------------------------------------------------------
* Emissions data from Texas Regional Haze SIP, Appendix 10.4b.

    Texas's use of 2018 projections also impacted the potential
emission reductions and cost of available controls for EGUs. For
example, Big Brown Unit 1's SO2 emissions in 2002 were
43,413 tpy. The IPM predictions that were incorporated into the 2018
emission level assume that a greater than \1/3\ reduction in these
emissions will occur in response to CAIR by switching to a coal with a
lower sulfur content, resulting in a 2018 SO2 emission level
of 23,142 tpy. Texas's cost-effectiveness calculation for post-
combustion controls on Big Brown Unit 1 was based on reducing that
projected 2018 SO2 emission level of 23,142 tpy by 90
percent, resulting in a reduction of 20,828 tpy. This results in a cost
of $32,766,310/yr, or a cost-effectiveness calculation of $1,573/ton.
However, the installation of a scrubber would allow Big Brown
flexibility in fuel choice thus allowing the unit to continue to burn
the higher average sulfur fuel it currently burns, instead of moving to
the low sulfur coal predicted by IPM. There was no enforceable
commitment for these emission reductions at Big Brown with the company
preferring the flexibility afforded under CAIR and thus it was
unreasonable for Texas to rely on these projected reductions as a
starting point for evaluating controls for this and other EGUs without
consideration of how the uncertainty in 2018 IPM projections may impact
their analysis.
    Big Brown Unit 1 SO2 emissions in 2006 were 49,777
tons.\98\ The issue of scrubber efficiency aside, a reduction of 90
percent from these actual emission levels would result in an
SO2 reduction of approximately 44,800 tpy. While the
numerator ($) in the cost-effectiveness metric of $/ton will increase
slightly beyond what was estimated by Alpine Geophysics due to an
increased sulfur loading to the scrubber, the denominator (tons) would
increase by more than 100 percent, thus improving (lowering) the
overall cost-effectiveness of controlling Big Brown Unit 1
significantly. Estimates for scrubbers at Monticello are similarly
impacted by the cost methodology used by Texas in estimating cost-
effectiveness on a cost-per-ton basis. Similarly, the visibility
benefits of controls estimated by Texas were based only on the
estimated additional emission reductions beyond what was already
estimated to occur under CAIR in 2018. Accounting for the full
reductions that would result from installation of the scrubbers based
on historical emissions at the time would result in larger emission
reductions and therefore, larger estimated visibility benefits from
controls.
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    \98\ 2006 was the most recent year for which complete annual
emissions data was available prior to Texas issuing the draft
Regional Haze SIP for public comment.

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    For these reasons, it was unreasonable for Texas to rely on the
2018 projections without consideration of uncertainty and how these
assumptions may impact their analysis. Texas should have recognized
that implementation of reasonable controls under the Regional Haze Rule
would likely not be in addition to anticipated reductions due to CAIR
predicted by IPM but would replace or complement any controls predicted
by IPM.
3. Weighing of the Four Statutory Factors and Visibility Benefits
    After consideration of the four statutory factors and other
applicable factors, States must weigh the factors and include a
demonstration showing how these factors were taken into consideration
in establishing the goal as required under Section 51.308(d)(1)(i)(A)
and (d)(1)(ii). Texas unreasonably weighed the costs of compliance and
the visibility benefits of controls, which resulted in unreasonable
conclusions.
a. Cost of Compliance
    Texas's use of annualized aggregate costs in determining whether
controls were necessary to make reasonable progress for the first
planning period was unreasonable and inconsistent with the CAA. In
looking at the costs of compliance as part of its four-factor analysis,
Texas stated that the total annualized aggregate cost of $324,300,000
was too high in light of the imperceptible visibility benefits of
controls.\99\ For reasons explained in section V.B.3.c, we find that
Texas's characterization and consideration of visibility benefits was
both flawed and unreasonable. Focusing on costs, the figure of
approximately $324 million reflects the annualized cost of controls on
the entire group of sources that Texas selected for analysis under the
four factors. As stated previously, states have flexibility in how they
consider the four factors; however, such flexibility must be exercised
in a reasonable manner. While determining that a total cost of $324
million was too high, Texas provided no context or support as to why
that figure is too high, and importantly, what range of costs would be
reasonable. This is especially problematic when considering that Texas
already applied a cost-effectiveness threshold of $2,700/ton to ``limit
the proposed controls group to cost effective measures'' \100\ and thus
eliminate sources for which they deemed controls as too costly. Thus,
pointing to the $324 million total annual cost as too expensive
seemingly contradicts Texas's determination that controls on these
sources are cost-effective. Rather, all that can be determined from
Texas's use of the aggregate annualized cost is that it represents the
sum total of the costs of controls for 45 units that impact one or more
Class I areas in Texas or nearby States and that Texas had previously
determined were cost effective as they were below its $2,700/ton cost-
threshold. As such, the way Texas relied on the annual aggregate cost
of controls was irrational and did not constitute a reasonable
consideration of the costs of compliance as required by the CAA and the
RHR.
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    \99\ See Texas Regional Haze SIP, Table 10-5.
    \100\ See Texas Regional Haze SIP at 10-7.
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b. Texas's Approach in Grouping Sources
    The way Texas grouped sources led to unreasonable results when
weighing the factors--namely it included multiple sources that inflated
the total cost of controls without providing a corresponding reduction
in visibility impairment. Texas constructed a potential control set
consisting of a mix of large and small sources, located at various
distances from Class I areas, with a large geographical distribution.
While on its face, this selection of controls and sources appears broad
and comprehensive, in analyzing how Texas constructed its control set
and mixture of sources, we find several flaws and therefore find the
analysis unreasonable. Because of the variation in size, type, and
location of these sources, the potential to impact visibility and
potential visibility benefit from controls at a given Class I area can
vary greatly between the identified sources. This potential control set
identified by Texas included controls on sources that would likely
result in significant visibility benefits at several Class I areas
(such as sources with high emissions and tall stacks), but also
included controls on many sources with much less anticipated visibility
benefits (such as sources with lower emissions and shorter stacks,
located at greater distances to the Class I areas). Because Texas only
estimated the visibility benefit by grouping all the controls together,
it was not able to appropriately assess the potential benefit of
controlling a more refined grouping of sources with significant, and
potentially cost-effective, visibility benefits. While we are not
suggesting that Texas was required to weigh the four factors and
visibility benefits on a source-specific basis, the grouping of sources
like the Bryans Mill Plant and the Celanese Chemical Manufacturing
Plant together with sources like Big Brown unreasonably inflated the
total cost of controls without providing a corresponding reduction in
visibility impairment. Thus, Texas failed to adequately justify why
including sources with very dissimilar potential visibility benefits in
the same group was reasonable.
    The significant visibility benefits of controls on some sources
being grouped together with controls on other sources that provided
little visibility benefit only served to increase the total annual cost
figures for the entire potential control set. For example, Texas
identified SO2 controls at the two Big Brown units to be
approximately $1,500/ton, significantly less than its $2,700/ton
threshold. These controls were estimated to achieve greater than 40,000
tpy SO2 emission reductions and would result in important
visibility benefits given that the Big Brown units have tall stacks and
a Q/d greater than 50 at surrounding Class I areas.\101\ Big Brown and
the other EGUs included in Texas's evaluated control set have Q/d
values greater than 5 at all ten Class I areas evaluated in Texas's
estimation of visibility benefits, and these emission reductions were
included in the estimation of potential visibility benefits at all ten
areas. In the same potential control set, Texas included SO2
controls at other sources with estimated costs similar or more
expensive than those at Big Brown, but with considerably lower
SO2 emissions reductions and lower Q/d. For instance, in the
same control set Texas identified SO2 controls at the Bryans
Mill Plant estimated to cost approximately $1,425/ton (similar to the
Big Brown units), but with estimated SO2 emission reductions
of only approximately 1,330 tpy. The Bryans Mill Plant has a Q/d less
than 10 at any given surrounding Class I areas and thus the visibility
benefits of SO2 controls on this source are anticipated to
be much lower than the visibility benefits of SO2 controls
on Big Brown. In Texas's estimation of visibility benefits, emission
reductions at Bryans Mills Plant were only included in the estimation
of visibility benefits at Caney Creek (Q/d = 8.2). The Q/d values for
all other Class I areas were so low (less than 5) that Texas assumed
that no visibility benefit would result at these Class I areas from
reductions at the Bryans Mills Plant. Texas also included in the same
potential control set SO2 controls at the Celanese Chemical

Manufacturing Plant that were estimated to be approximately $2,658/ton,
but with estimated SO2 emission reductions of only
approximately 1,760 tpy. The Celanese Chemical Manufacturing Plant has
a Q/d less than 9 at any given surrounding Class I area and thus the
visibility benefits of this SO2 control are anticipated to
be much lower than the visibility benefits of SO2 controls