[Federal Register Volume 89, Number 199 (Tuesday, October 15, 2024)]
[Proposed Rules]
[Pages 83338-83375]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-23341]



[[Page 83337]]

Vol. 89

Tuesday,

No. 199

October 15, 2024

Part V





Environmental Protection Agency





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





40 CFR Part 52





Air Quality State Implementation Plans; Partial Approval, Partial 
Disapproval and Promulgation; Texas; Regional Haze; Proposed Rule

Federal Register / Vol. 89 , No. 199 / Tuesday, October 15, 2024 / 
Proposed Rules

[[Page 83338]]


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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2021-0539; FRL-12282-01-R6]


Air Quality State Implementation Plans; Partial Approval, Partial 
Disapproval and Promulgation; Texas; Regional Haze

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
partially approve and partially disapprove the regional haze State 
implementation plan (SIP) revision submitted by Texas on July 20, 2021, 
under the Clean Air Act (CAA) and EPA's Regional Haze Rule (RHR) for 
the program's second implementation period. Texas's SIP submission 
addresses the requirement that states must periodically revise their 
long-term strategies for making reasonable progress towards the 
national goal of preventing any future, and remedying any existing, 
anthropogenic impairment of visibility, including regional haze, in 
mandatory Class I Federal areas. The SIP submission also addresses 
other applicable requirements for the second implementation period of 
the regional haze program. The EPA is taking this action pursuant to 
sections 110 and 169A of the Clean Air Act.

DATES: Written comments must be received on or before November 14, 
2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R06-
OAR-2021-0539 at https://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. For additional submission 
methods, please contact the person identified in the FOR FURTHER 
INFORMATION CONTACT section. For the full EPA public comment policy, 
information about CBI or multimedia submissions, and general guidance 
on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket: The index to the docket for this action is available 
electronically at www.regulations.gov. While all documents in the 
docket are listed in the index, some information may not be publicly 
available due to docket file size restrictions or content (e.g., CBI).

FOR FURTHER INFORMATION CONTACT: Jennifer Huser, U.S. Environmental 
Protection Agency, Region 6, 1201 Elm St., Suite 500, Dallas, Texas 
75270, at (214) 665-7347, or by email at <a href="/cdn-cgi/l/email-protection#ace4d9dfc9de82e6c9c2c2c5cac9deecc9dccd82cbc3da"><span class="__cf_email__" data-cfemail="6b231e180e1945210e0505020d0e192b0e1b0a450c041d">[email protected]</span></a>.

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

Table of Contents

I. What action is the EPA proposing?
II. Background and Requirements for Regional Haze Plans
    A. Regional Haze Background
    B. Roles of Agencies in Addressing Regional Haze
III. Requirements for Regional Haze Plans for the Second 
Implementation Period
    A. Identification of Class I Areas
    B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress
    C. Long-Term Strategy for Regional Haze
    D. Reasonable Progress Goals
    E. Monitoring Strategy and Other State Implementation Plan 
Requirements
    F. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    G. Requirements for State and Federal Land Manager Coordination
IV. The EPA's Evaluation of Texas's Regional Haze Submission for the 
Second Implementation Period
    A. Background on Texas's First Implementation Period SIP 
Submission
    B. Texas's Second Implementation Period SIP Submission and the 
EPA's Evaluation
    C. Identification of Class I Areas
    1. Texas Class I Areas
    2. Identification of Impacted Class I Areas Outside the State
    D. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress
    E. Long-Term Strategy for Regional Haze
    1. Source Selection
    2. Four Factor Analysis
    3. Additional Long-Term Strategy Requirements
    F. Reasonable Progress Goals
    G. Reasonably Attributable Visibility Impairment (RAVI)
    H. Monitoring Strategy and Other Implementation Plan 
Requirements
    I. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    J. Requirements for State and Federal Land Manager Coordination
V. Proposed Action
VI. Environmental Justice Considerations
VII. Statutory and Executive Order Reviews

I. What action is the EPA proposing?

    On July 20, 2021, the Texas Commission on Environmental Quality 
(TCEQ) submitted a plan (``2021 Texas Regional Haze Plan'' or ``Texas 
RH SIP'') to the EPA to satisfy the regional haze program requirements 
pursuant to CAA sections 169A and 40 CFR 51.308. The EPA is proposing 
to partially approve and partially disapprove Texas's Regional Haze 
plan for the second planning (implementation) period. Consistent with 
section 110(k)(3) of the CAA, the EPA may partially approve portions of 
a submittal if those elements meet all applicable requirements and may 
disapprove the remainder so long as the elements are fully 
separable.\1\ As required by section 169A of the CAA, the Federal RHR 
calls for State and Federal agencies to work together to improve 
visibility in 156 national parks and wilderness areas. The rule 
requires the states, in coordination with the EPA, National Park 
Service (NPS), U.S. Fish and Wildlife Service (FWS), Forest Service 
(FS), and other interested parties, to develop and implement air 
quality protection plans to reduce the pollution that causes visibility 
impairment. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>), and, in 
some cases, volatile organic compounds (VOC) and ammonia 
(NH<INF>3</INF>)). As discussed in further detail below, the EPA is 
proposing to find that Texas has submitted a Regional Haze plan that 
does not meet all the Regional Haze requirements for the second 
planning period. For the reasons described in this document, the EPA is 
proposing to approve the elements of Texas's plan related to 
requirements contained in 40

[[Page 83339]]

CFR 51.308(f)(1), (f)(4), (f)(5),\2\ and (f)(6). The EPA is proposing 
to disapprove the elements of Texas's plan related to requirements 
contained in 40 CFR 51.308(f)(2), (f)(3), and (i). The State's 
submission can be found in the docket for this action.
---------------------------------------------------------------------------

    \1\ See CAA section 110(k)(3) and July 1992 EPA memorandum 
titled ``Processing of State Implementation Plan (SIP) Submittals'' 
from John Calcagni, at https://www.epa.gov/sites/default/files/2015-07/documents/procsip.pdf.
    \2\ 40 CFR 51.308(f)(5) requires that the second planning period 
SIP revision address the requirements listed in (g)(1) through 
(g)(5).
---------------------------------------------------------------------------

II. Background and Requirements for Regional Haze Plans

A. Regional Haze Background

    In the 1977 CAA Amendments, Congress created a program for 
protecting visibility in the nation's mandatory Class I Federal areas, 
which include certain national parks and wilderness areas.\3\ CAA 169A. 
The CAA establishes as a national goal the ``prevention of any future, 
and the remedying of any existing, impairment of visibility in 
mandatory class I Federal areas which impairment results from manmade 
air pollution.'' CAA 169A(a)(1). The CAA further directs the EPA to 
promulgate regulations to assure reasonable progress toward meeting 
this national goal. CAA 169A(a)(4). On December 2, 1980, the EPA 
promulgated regulations to address visibility impairment in mandatory 
Class I Federal areas (hereinafter referred to as ``Class I areas'') 
that is ``reasonably attributable'' to a single source or small group 
of sources. (45 FR 80084, December 2, 1980). These regulations, 
codified at 40 CFR 51.300 through 51.307, represented the first phase 
of the EPA's efforts to address visibility impairment. In 1990, 
Congress added section 169B to the CAA to further address visibility 
impairment, specifically, impairment from regional haze. CAA 169B. The 
EPA promulgated the RHR, codified at 40 CFR 51.308,\4\ on July 1, 1999. 
(64 FR 35714, July 1, 1999). These regional haze regulations are a 
central component of the EPA's comprehensive visibility protection 
program for Class I areas.
---------------------------------------------------------------------------

    \3\ Areas statutorily designated as mandatory Class I Federal 
areas consist of national parks exceeding 6,000 acres, wilderness 
areas and national memorial parks exceeding 5,000 acres, and all 
international parks that were in existence on August 7, 1977. CAA 
162(a). There are 156 mandatory Class I areas. The list of areas to 
which the requirements of the visibility protection program apply is 
in 40 CFR part 81, subpart D.
    \4\ In addition to the generally applicable regional haze 
provisions at 40 CFR 51.308, the 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 applicable only for specific jurisdictions' regional 
haze plans submitted no later than December 17, 2007, and thus are 
not relevant here.
---------------------------------------------------------------------------

    Regional haze is visibility impairment that is produced by a 
multitude of anthropogenic sources and activities which are located 
across a broad geographic area and that emit pollutants that impair 
visibility. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>), and, in 
some cases, volatile organic compounds (VOC) and ammonia 
(NH<INF>3</INF>)). Fine particle precursors react in the atmosphere to 
form fine particulate matter (PM<INF>2.5</INF>), which impairs 
visibility by scattering and absorbing light. Visibility impairment 
reduces the perception of clarity and color, as well as visible 
distance.\5\
---------------------------------------------------------------------------

    \5\ There are several ways to measure the amount of visibility 
impairment, i.e., haze. One such measurement is the deciview, which 
is the principal metric used by the RHR. Under many circumstances, a 
change in one deciview will be perceived by the human eye to be the 
same on both clear and hazy days. The deciview is unitless. It is 
proportional to the logarithm of the atmospheric extinction of 
light, which is the perceived dimming of light due to its being 
scattered and absorbed as it passes through the atmosphere. 
Atmospheric light extinction (b\ext\) is a metric used for 
expressing visibility and is measured in inverse megameters (Mm\-
1\). The EPA's Guidance on Regional Haze State Implementation Plans 
for the Second Implementation Period (``2019 Guidance'') offers the 
flexibility for the use of light extinction in certain cases. Light 
extinction can be simpler to use in calculations than deciviews, 
since it is not a logarithmic function. See, e.g., 2019 Guidance at 
16, 19, https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period, The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park (August 
20, 2019). The formula for the deciview is 10 ln (b\ext\)/10 Mm-1). 
40 CFR 51.301.
---------------------------------------------------------------------------

    To address regional haze visibility impairment, the 1999 RHR 
established an iterative planning process that requires both states in 
which Class I areas are located and states ``the emissions from which 
may reasonably be anticipated to cause or contribute to any impairment 
of visibility'' in a Class I area to periodically submit SIP revisions 
to address such impairment. CAA 169A(b)(2); \6\ see also 40 CFR 
51.308(b), (f) (establishing submission dates for iterative regional 
haze SIP revisions); (64 FR at 35768, July 1, 1999). 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,'' CAA 169A(b)(2)(B); 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 the best 
available retrofit technology (BART). CAA 169A(b)(2)(A); 40 CFR 
51.308(d), (e). States' first regional haze SIPs were due by December 
17, 2007, 40 CFR 51.308(b), with subsequent SIP submissions containing 
updated long-term strategies originally due July 31, 2018, and every 
ten years thereafter. (64 FR at 35768, July 1, 1999). The EPA 
established in the 1999 RHR 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.\7\ Id. at 
35721.
---------------------------------------------------------------------------

    \6\ The RHR expresses the statutory requirement for states to 
submit plans addressing out-of-state Class I areas by providing that 
states must address visibility impairment ``in each mandatory Class 
I Federal area located outside the State that may be affected by 
emissions from within the State.'' 40 CFR 51.308(d), (f).
    \7\ In addition to each of the fifty states, the EPA also 
concluded that the Virgin Islands and District of Columbia must also 
submit regional haze SIPs because they either contain a Class I area 
or contain sources whose emissions are reasonably anticipated to 
contribute regional haze in a Class I area. See 40 CFR 51.300(b), 
(d)(3).
---------------------------------------------------------------------------

    Much of the focus in the first implementation period of the 
regional haze program, which ran from 2007 through 2018, was on 
satisfying states' BART obligations. First implementation period SIPs 
were additionally required to contain long-term strategies for making 
reasonable progress toward the national visibility goal, of which BART 
is one component. The core required elements for the first 
implementation period SIPs (other than BART) are laid out in 40 CFR 
51.308(d). Those provisions required that states containing Class I 
areas establish reasonable progress goals (RPGs) that are measured in 
deciviews and reflect the anticipated visibility conditions at the end 
of the implementation period including from implementation of states' 
long-term strategies. The first planning period RPGs were required to 
provide for an improvement in visibility for the most impaired days 
over the period of the implementation plan and ensure no degradation in 
visibility for the least impaired days over the same period. In 
establishing the RPGs for any Class I area in a State, the State was 
required to consider four statutory factors: 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. CAA 169A(g)(1); 40 CFR 51.308(d)(1).
    States were also required to calculate baseline (using the five 
year period of 2000-2004) and natural visibility conditions (i.e., 
visibility conditions without anthropogenic visibility

[[Page 83340]]

impairment) for each Class I area, and to calculate the linear rate of 
progress needed to attain natural visibility conditions, assuming a 
starting point of baseline visibility conditions in 2004 and ending 
with natural conditions in 2064. This linear interpolation is known as 
the uniform rate of progress (URP) and is used as a tracking metric to 
help states assess the amount of progress they are making towards the 
national visibility goal over time in each Class I area.\8\ 40 CFR 
51.308(d)(1)(i)(B), (d)(2). The 1999 RHR also provided that States' 
long-term strategies must include the ``enforceable emissions 
limitations, compliance, schedules, and other measures as necessary to 
achieve the reasonable progress goals.'' 40 CFR 51.308(d)(3). In 
establishing their long-term strategies, states are required to consult 
with other states that also contribute to visibility impairment in a 
given Class I area and include all measures necessary to obtain their 
shares of the emission reductions needed to meet the RPGs. 40 CFR 
51.308(d)(3)(i), (ii). Section 51.308(d) also contains seven additional 
factors states must consider in formulating their long-term strategies, 
40 CFR 51.308(d)(3)(v), as well as provisions governing monitoring and 
other implementation plan requirements. 40 CFR 51.308(d)(4). Finally, 
the 1999 RHR required states to submit periodic progress reports--SIP 
revisions due every five years that contain information on states' 
implementation of their regional haze plans and an assessment of 
whether anything additional is needed to make reasonable progress, see 
40 CFR 51.308(g), (h)--and to consult with the Federal Land Manager(s) 
\9\ (FLMs) responsible for each Class I area according to the 
requirements in CAA 169A(d) and 40 CFR 51.308(i).
---------------------------------------------------------------------------

    \8\ The EPA established the URP framework in the 1999 RHR to 
provide ``an equitable analytical approach'' to assessing the rate 
of visibility improvement at Class I areas across the country. The 
starting point for the URP analysis is 2004 and the endpoint was 
calculated based on the amount of visibility improvement that was 
anticipated to result from implementation of existing CAA programs 
over the period from the mid-1990s to approximately 2005. Assuming 
this rate of progress would continue into the future, the EPA 
determined that natural visibility conditions would be reached in 60 
years, or 2064 (60 years from the baseline starting point of 2004). 
However, the EPA did not establish 2064 as the year by which the 
national goal must be reached. 64 FR at 35731-32. That is, the URP 
and the 2064 date are not enforceable targets but are rather tools 
that ``allow for analytical comparisons between the rate of progress 
that would be achieved by the state's chosen set of control measures 
and the URP.'' (82 FR 3078, 3084, January 10, 2017).
    \9\ The EPA's regulations define ``Federal Land Manager'' as 
``the Secretary of the department with authority over the Federal 
Class I area (or the Secretary's designee) or, with respect to 
Roosevelt-Campobello International Park, the Chairman of the 
Roosevelt-Campobello International Park Commission.'' 40 CFR 51.301.
---------------------------------------------------------------------------

    On January 10, 2017, the EPA promulgated revisions to the RHR, (82 
FR 3078, January 10, 2017), that apply for the second and subsequent 
implementation periods. The 2017 rulemaking made several changes to the 
requirements for regional haze SIPs to clarify States' obligations and 
streamline certain regional haze requirements. The revisions to the 
regional haze program for the second and subsequent implementation 
periods focused on the requirement that States' SIPs contain long-term 
strategies for making reasonable progress towards the national 
visibility goal. The reasonable progress requirements as revised in the 
2017 rulemaking (referred to here as the 2017 RHR Revisions) are 
codified at 40 CFR 51.308(f). Among other changes, the 2017 RHR 
Revisions adjusted the deadline for States to submit their second 
implementation period SIPs from July 31, 2018, to July 31, 2021, 
clarified the order of analysis and the relationship between RPGs and 
the long-term strategy, and focused on making visibility improvements 
on the days with the most anthropogenic visibility impairment, as 
opposed to the days with the most visibility impairment overall. The 
EPA also revised requirements of the visibility protection program 
related to periodic progress reports and FLM consultation. The specific 
requirements applicable to second implementation period regional haze 
SIP submissions are addressed in detail below.
    The EPA provided guidance to the states for their second 
implementation period SIP submissions in the preamble to the 2017 RHR 
Revisions as well as in subsequent, stand-alone guidance documents. In 
August 2019, the EPA issued ``Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period'' (``2019 
Guidance'').\10\ On July 8, 2021, the EPA issued a memorandum 
containing ``Clarifications Regarding Regional Haze State 
Implementation Plans for the Second Implementation Period'' (``2021 
Clarifications Memo'').\11\ Additionally, the EPA further clarified the 
recommended procedures for processing ambient visibility data and 
optionally adjusting the URP to account for international anthropogenic 
and prescribed fire impacts in two technical guidance documents: the 
December 2018 ``Technical Guidance on Tracking Visibility Progress for 
the Second Implementation Period of the Regional Haze Program'' (``2018 
Visibility Tracking Guidance''),\12\ and the June 2020 ``Recommendation 
for the Use of Patched and Substituted Data and Clarification of Data 
Completeness for Tracking Visibility Progress for the Second 
Implementation Period of the Regional Haze Program'' and associated 
Technical Addendum (``2020 Data Completeness Memo'').\13\
---------------------------------------------------------------------------

    \10\ Guidance on Regional Haze State Implementation Plans for 
the Second Implementation Period. https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period The EPA Office of Air Quality Planning and 
Standards, Research Triangle Park (August 20, 2019).
    \11\ Clarifications Regarding Regional Haze State Implementation 
Plans for the Second Implementation Period. https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf. The EPA Office of Air Quality Planning and Standards, 
Research Triangle Park (July 8, 2021).
    \12\ Technical Guidance on Tracking Visibility Progress for the 
Second Implementation Period of the Regional Haze Program. https://www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional The EPA Office of Air 
Quality Planning and Standards, Research Triangle Park. (December 
20, 2018).
    \13\ Recommendation for the Use of Patched and Substituted Data 
and Clarification of Data Completeness for Tracking Visibility 
Progress for the Second Implementation Period of the Regional Haze 
Program. https://www.epa.gov/visibility/memo-and-technical-addendum-ambient-data-usage-and-completeness-regional-haze-program The EPA 
Office of Air Quality Planning and Standards, Research Triangle Park 
(June 3, 2020).
---------------------------------------------------------------------------

    As explained in the 2021 Clarifications Memo, the EPA intends the 
second implementation period of the regional haze program to secure 
meaningful reductions in visibility impairing pollutants that build on 
the significant progress states have achieved to date. The Agency also 
recognizes that analyses regarding reasonable progress are State-
specific and that, based on states' and sources' individual 
circumstances, what constitutes reasonable reductions in visibility 
impairing pollutants will vary from State-to-State. While there exist 
many opportunities for states to leverage both ongoing and upcoming 
emission reductions under other CAA programs, the Agency expects states 
to undertake rigorous reasonable progress analyses that identify 
further opportunities to advance the national visibility goal 
consistent with the statutory and regulatory requirements. See 
generally 2021 Clarifications Memo. This is consistent with Congress's 
determination that a visibility protection program is needed in 
addition to the CAA's National Ambient Air Quality Standards and 
Prevention of Significant Deterioration programs, as

[[Page 83341]]

further emission reductions may be necessary to adequately protect 
visibility in Class I areas throughout the country.\14\
---------------------------------------------------------------------------

    \14\ See, e.g., H.R. Rep No. 95-294 at 205 (``In determining how 
to best remedy the growing visibility problem in these areas of 
great scenic importance, the committee realizes that as a matter of 
equity, the national ambient air quality standards cannot be revised 
to adequately protect visibility in all areas of the country.''), 
(``the mandatory class I increments of [the PSD program] do not 
adequately protect visibility in class I areas'').
---------------------------------------------------------------------------

B. Roles of Agencies in Addressing Regional Haze

    Because the air pollutants and pollution affecting visibility in 
Class I areas can be transported over long distances, successful 
implementation of the regional haze program requires long-term, 
regional coordination among multiple jurisdictions and agencies that 
have responsibility for Class I areas and the emissions that impact 
visibility in those areas. To address regional haze, states need to 
develop strategies in coordination with one another, considering the 
effect of emissions from one jurisdiction on the air quality in 
another. Five regional planning organizations (RPOs),\15\ which include 
representation from State and Tribal governments, the EPA, and FLMs, 
were developed in the lead-up to the first implementation period to 
address regional haze. RPOs evaluate technical information to better 
understand how emissions from State and Tribal land impact Class I 
areas across the country, pursue the development of regional strategies 
to reduce emissions of particulate matter and other pollutants leading 
to regional haze, and help states meet the consultation requirements of 
the RHR.
---------------------------------------------------------------------------

    \15\ RPOs are sometimes also referred to as ``multi-
jurisdictional organizations,'' or MJOs. For the purposes of this 
notice, the terms RPO and MJO are synonymous.
---------------------------------------------------------------------------

    The Central Regional Air Planning Association (CenRAP), one of the 
five RPOs described above, that Texas was a member of during the first 
planning period, was a collaborative effort of State governments, 
Tribal governments, and Federal agencies established to initiate and 
coordinate activities associated with the management of regional haze, 
visibility, and other air quality issues in parts of the Great Plains, 
Midwest, Southwest, and South Regions of the United States.
    After the first planning period SIPs were submitted, the planning 
was shifted to the Central State Air Resources Agencies (CenSARA). 
CenSARA was established to promote the exchange of air quality 
information, knowledge, experience, and data among and between 
participating organizations and other interested parties. It supports 
the membership with training and policy and technical projects. CenSARA 
supports and promotes collaborative efforts of State governments to 
initiate and coordinate activities associated with the management of 
regional haze and other air quality issues in parts of the Great 
Plains, Midwest, Southwest, and South Regions of the United States. 
Member states include: Arkansas, Iowa, Kansas, Louisiana, Missouri, 
Nebraska, Oklahoma, and Texas. Unlike CenRAP, CenSARA has solely State 
and local government members. However, CenSARA does reach out to Tribal 
and Federal partners. The Federal partners of CenSARA are the EPA, the 
NPS, the FWS, and FS.

III. Requirements for Regional Haze Plans for the Second Implementation 
Period

    Under the CAA and EPA's regulations, all 50 States, the District of 
Columbia, and the U.S. Virgin Islands are required to submit regional 
haze SIPs satisfying the applicable requirements for the second 
implementation period of the regional haze program by July 31, 2021. 
Each state's SIP must contain a long-term strategy for making 
reasonable progress toward meeting the national goal of remedying any 
existing and preventing any future anthropogenic visibility impairment 
in Class I areas. CAA 169A(b)(2)(B). To this end, Sec.  51.308(f) lays 
out the process by which states determine what constitutes their long-
term strategies, with the order of the requirements in Sec.  
51.308(f)(1) through (f)(3) generally mirroring the order of the steps 
in the reasonable progress analysis \16\ and (f)(4) through (f)(6) 
containing additional, related requirements. Broadly speaking, a State 
first must identify the Class I areas within the State and determine 
the Class I areas outside the State in which visibility may be affected 
by emissions from the State. These are the Class I areas that must be 
addressed in the state's long-term strategy. See 40 CFR 51.308(f), 
(f)(2). For each Class I area within its borders, a State must then 
calculate the baseline, current, and natural visibility conditions for 
that area, as well as the visibility improvement made to date and the 
URP. See 40 CFR 51.308(f)(1). Each State having a Class I area and/or 
emissions that may affect visibility in a Class I area must then 
develop a long-term strategy that includes the enforceable emission 
limitations, compliance schedules, and other measures that are 
necessary to make reasonable progress in such areas. A reasonable 
progress determination is based on applying the four factors in CAA 
section 169A(g)(1) to sources of visibility impairing pollutants that 
the State has selected to assess for controls for the second 
implementation period. Additionally, as further explained below, the 
RHR at 40 CFR 51.3108(f)(2)(iv) separately provides five ``additional 
factors'' \17\ that states must consider in developing their long-term 
strategies. See 40 CFR 51.308(f)(2). A State evaluates potential 
emission reduction measures for those selected sources and determines 
which are necessary to make reasonable progress. Those measures are 
then incorporated into the state's long-term strategy. After a State 
has developed its long-term strategy, it then establishes RPGs for each 
Class I area within its borders by modeling the visibility impacts of 
all reasonable progress controls at the end of the second 
implementation period, i.e., in 2028, as well as the impacts of other 
requirements of the CAA. The RPGs include reasonable progress controls 
not only for sources in the State in which the Class I area is located, 
but also for sources in other states that contribute to visibility 
impairment in that area. The RPGs are then compared to the baseline 
visibility conditions and the URP to ensure that progress is being made 
towards the statutory goal of preventing any future and remedying any 
existing anthropogenic visibility impairment in Class I areas. 40 CFR 
51.308(f)(2)-(3).
---------------------------------------------------------------------------

    \16\ The EPA explained in the 2017 RHR Revisions that we were 
adopting new regulatory language in 40 CFR 51.308(f) that, unlike 
the structure in 51.308(d), ``tracked the actual planning 
sequence.'' (82 FR 3091, January 10, 2017).
    \17\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
---------------------------------------------------------------------------

    In addition to satisfying the requirements at 40 CFR 51.308(f) 
related to reasonable progress, the regional haze SIP revisions for the 
second implementation period must address the requirements in Sec.  
51.308(g)(1) through (5) pertaining to periodic reports describing 
progress towards the RPGs, 40 CFR 51.308(f)(5), as well as requirements 
for FLM consultation that apply to all visibility protection SIPs and 
SIP revisions. 40 CFR 51.308(i).
    A State must submit its regional haze SIP and subsequent SIP 
revisions to the EPA according to the requirements applicable to all 
SIP revisions under the CAA and EPA's regulations. See CAA 169A(b)(2); 
CAA 110(a). Upon EPA approval, a SIP is enforceable by the Agency and 
the public under the CAA.

[[Page 83342]]

If EPA finds that a State fails to make a required SIP revision, or if 
the EPA finds that a state's SIP is incomplete or disapproves the SIP, 
the Agency must promulgate a federal implementation plan (FIP) that 
satisfies the applicable requirements. CAA 110(c)(1).

A. Identification of Class I Areas

    The first step in developing a regional haze SIP is for a State to 
determine which Class I areas, in addition to those within its borders, 
``may be affected'' by emissions from within the State. In the 1999 
RHR, the EPA determined that all states contribute to visibility 
impairment in at least one Class I area, 64 FR at 35720-22, and 
explained that the statute and regulations lay out an ``extremely low 
triggering threshold'' for determining ``whether States should be 
required to engage in air quality planning and analysis as a 
prerequisite to determining the need for control of emissions from 
sources within their State.'' Id. at 35721.
    A State must determine which Class I areas must be addressed by its 
SIP by evaluating the total emissions of visibility impairing 
pollutants from all sources within the State. While the RHR does not 
require this evaluation to be conducted in any particular manner, EPA's 
2019 Guidance provides recommendations for how such an assessment might 
be accomplished, including by, where appropriate, using the 
determinations previously made for the first implementation period. 
2019 Guidance at 8-9. In addition, the determination of which Class I 
areas may be affected by a state's emissions is subject to the 
requirement in 40 CFR 51.308(f)(2)(iii) to ``document the technical 
basis, including modeling, monitoring, cost, engineering, and emissions 
information, on which the State is relying to determine the emission 
reduction measures that are necessary to make reasonable progress in 
each mandatory Class I Federal area it affects.''

B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    As part of assessing whether a SIP submission for the second 
implementation period is providing for reasonable progress towards the 
national visibility goal, the RHR contains requirements in Sec.  
51.308(f)(1) related to tracking visibility improvement over time. The 
requirements of this subsection apply only to states having Class I 
areas within their borders; the required calculations must be made for 
each such Class I area. EPA's 2018 Visibility Tracking Guidance \18\ 
provides recommendations to assist states in satisfying their 
obligations under Sec.  51.308(f)(1); specifically, in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP to account for the 
impacts of international anthropogenic emissions and prescribed fires. 
See 82 FR at 3103-05.
---------------------------------------------------------------------------

    \18\ The 2018 Visibility Tracking Guidance references and relies 
on parts of the 2003 Tracking Guidance: ``Guidance for Tracking 
Progress Under the Regional Haze Rule,'' which can be found at 
https://www3.epa.gov/ttnamti1/files/ambient/visible/tracking.pdf.
---------------------------------------------------------------------------

    The RHR requires tracking of visibility conditions on two sets of 
days: the clearest and the most impaired days. Visibility conditions 
for both sets of days are expressed as the average deciview index for 
the relevant five-year period (the period representing baseline or 
current visibility conditions). The RHR provides that the relevant sets 
of days for visibility tracking purposes are the 20% clearest (the 20% 
of monitored days in a calendar year with the lowest values of the 
deciview index) and 20% most impaired days (the 20% of monitored days 
in a calendar year with the highest amounts of anthropogenic visibility 
impairment).\19\ 40 CFR 51.301. A State must calculate visibility 
conditions for both the 20% clearest and 20% most impaired days for the 
baseline period of 2000-2004 and the most recent five-year period for 
which visibility monitoring data are available (representing current 
visibility conditions). 40 CFR 51.308(f)(1)(i), (iii). States must also 
calculate natural visibility conditions for the clearest and most 
impaired days,\20\ by estimating the conditions that would exist on 
those two sets of days absent anthropogenic visibility impairment. 40 
CFR 51.308(f)(1)(ii). Using all these data, states must then calculate, 
for each Class I area, the amount of progress made since the baseline 
period (2000-2004) and how much improvement is left to achieve to reach 
natural visibility conditions.
---------------------------------------------------------------------------

    \19\ This notice also refers to the 20% clearest and 20% most 
anthropogenically impaired days as the ``clearest'' and ``most 
impaired'' or ``most anthropogenically impaired'' days, 
respectively.
    \20\ The RHR at 40 CFR 51.308(f)(1)(ii) contains an error 
related to the requirement for calculating two sets of natural 
conditions values. The rule says ``most impaired days or the 
clearest days'' where it should say ``most impaired days and 
clearest days.'' This is an error that was intended to be corrected 
in the 2017 RHR Revisions but did not get corrected in the final 
rule language. This is supported by the preamble text at 82 FR 3098: 
``In the final version of 40 CFR 51.308(f)(1)(ii), an occurrence of 
``or'' has been corrected to ``and'' to indicate that natural 
visibility conditions for both the most impaired days and the 
clearest days must be based on available monitoring information.''
---------------------------------------------------------------------------

    Using the data for the set of most impaired days only, states must 
plot a line between visibility conditions in the baseline period and 
natural visibility conditions for each Class I area to determine the 
URP--the amount of visibility improvement, measured in deciviews, that 
would need to be achieved during each implementation period to achieve 
natural visibility conditions by the end of 2064. The URP is used in 
later steps of the reasonable progress analysis for informational 
purposes and to provide a non-enforceable benchmark against which to 
assess a Class I area's rate of visibility improvement.\21\ 
Additionally, in the 2017 RHR Revisions, the EPA provided states the 
option of proposing to adjust the endpoint of the URP to account for 
impacts of anthropogenic sources outside the United States and/or 
impacts of certain types of wildland prescribed fires. These 
adjustments, which must be approved by the EPA, are intended to avoid 
any perception that states should compensate for impacts from 
international anthropogenic sources and to give states the flexibility 
to determine that limiting the use of wildland-prescribed fire is not 
necessary for reasonable progress. 82 FR 3107 footnote 116.
---------------------------------------------------------------------------

    \21\ Being on or below the URP is not a ``safe harbor''; i.e., 
achieving the URP does not mean that a Class I area is making 
``reasonable progress'' and does not relieve a state from using the 
four statutory factors to determine what level of control is needed 
to achieve such progress. See, e.g., 82 FR at 3093.
---------------------------------------------------------------------------

    The EPA's 2018 Visibility Tracking Guidance can be used to help 
satisfy the 40 CFR 51.308(f)(1) requirements, including in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP. In addition, the 2020 
Data Completeness Memo provides recommendations on the data 
completeness language referenced in Sec.  51.308(f)(1)(i) and provides 
updated natural conditions estimates for each Class I area.

C. Long-Term Strategy for Regional Haze

    The core component of a regional haze SIP submission is a long-term 
strategy that addresses regional haze in each Class I area within a 
state's borders and each Class I area that may be affected by emissions 
from the State. The long-term strategy ``must include the enforceable 
emissions limitations, compliance schedules, and other measures that 
are necessary to make reasonable progress, as determined pursuant to 
(f)(2)(i) through (iv).'' 40

[[Page 83343]]

CFR 51.308(f)(2). The amount of progress that is ``reasonable 
progress'' is based on applying the four statutory factors in CAA 
section 169A(g)(1) in an evaluation of potential control options for 
sources of visibility impairing pollutants, which is referred to as a 
``four-factor'' analysis. The outcome of that analysis is the emission 
reduction measures that a particular source or group of sources needs 
to implement to make reasonable progress towards the national 
visibility goal. See 40 CFR 51.308(f)(2)(i). Emission reduction 
measures that are necessary to make reasonable progress may be either 
new, additional control measures for a source, or they may be the 
existing emission reduction measures that a source is already 
implementing. See 2019 Guidance at 43; 2021 Clarifications Memo at 8-
10. Such measures must be represented by ``enforceable emissions 
limitations, compliance schedules, and other measures'' (i.e., any 
additional compliance tools) in a state's long-term strategy in its 
SIP. 40 CFR 51.308(f)(2).
    Section 51.308(f)(2)(i) provides the requirements for the four-
factor analysis. The first step of this analysis entails selecting the 
sources to be evaluated for emission reduction measures; to this end, 
the RHR requires states to consider ``major and minor stationary 
sources or groups of sources, mobile sources, and area sources'' of 
visibility impairing pollutants for potential four-factor control 
analysis. 40 CFR 51.308(f)(2)(i). A threshold question at this step is 
which visibility impairing pollutants will be analyzed. As EPA 
previously explained, consistent with the first implementation period, 
EPA generally expects that each State will analyze at least 
SO<INF>2</INF> and NO<INF>X</INF> in selecting sources and determining 
control measures. See 2019 Guidance at 12; 2021 Clarifications Memo at 
4. A State that chooses not to consider at least these two pollutants 
should demonstrate why such consideration would be unreasonable. 2021 
Clarifications Memo at 4.
    While states have the option to analyze all sources, the 2019 
Guidance explains that ``an analysis of control measures is not 
required for every source in each implementation period,'' and that 
``[s]electing a set of sources for analysis of control measures in each 
implementation period is . . . consistent with the Regional Haze Rule, 
which sets up an iterative planning process and anticipates that a 
State may not need to analyze control measures for all its sources in a 
given SIP revision.'' 2019 Guidance at 9. However, given that source 
selection is the basis of all subsequent control determinations, a 
reasonable source selection process ``should be designed and conducted 
to ensure that source selection results in a set of pollutants and 
sources the evaluation of which has the potential to meaningfully 
reduce their contributions to visibility impairment.'' 2021 
Clarifications Memo at 3.
    EPA explained in the 2021 Clarifications Memo that each State has 
an obligation to submit a long-term strategy that addresses the 
regional haze visibility impairment that results from emissions from 
within that State. Thus, source selection should focus on the in-state 
contribution to visibility impairment and be designed to capture a 
meaningful portion of the state's total contribution to visibility 
impairment in Class I areas. A State should not decline to select its 
largest in-state sources on the basis that there are even larger out-
of-state contributors. 2021 Clarifications Memo at 4.\22\
---------------------------------------------------------------------------

    \22\ Similarly, in responding to comments on the 2017 RHR 
Revisions the EPA explained that ``[a] state should not fail to 
address its many relatively low-impact sources merely because it 
only has such sources and another state has even more low-impact 
sources and/or some high impact sources.'' Responses to Comments on 
Protection of Visibility: Amendments to Requirements for State 
Plans; Proposed Rule (81 FR 26942, May 4, 2016) at 87-88.
---------------------------------------------------------------------------

    Thus, while states have discretion to choose any source selection 
methodology that is reasonable, whatever choices they make should be 
reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that 
a state's SIP submission include ``a description of the criteria it 
used to determine which sources or groups of sources it evaluated.'' 
The technical basis for source selection, which may include methods for 
quantifying potential visibility impacts such as emissions divided by 
distance metrics, trajectory analyses, residence time analyses, and/or 
photochemical modeling, must also be appropriately documented, as 
required by 40 CFR 51.308(f)(2)(iii).
    Once a State has selected the set of sources, the next step is to 
determine the emissions reduction measures for those sources that are 
necessary to make reasonable progress for the second implementation 
period.\23\ This is accomplished by considering the four factors--``the 
costs of compliance, the time necessary for compliance, and the energy 
and nonair quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' CAA 169A(g)(1). The EPA has explained that the four-
factor analysis is an assessment of potential emission reduction 
measures (i.e., control options) for sources; ``use of the terms 
`compliance' and `subject to such requirements' in section 169A(g)(1) 
strongly indicates that Congress intended the relevant determination to 
be the requirements with which sources would have to comply to satisfy 
the CAA's reasonable progress mandate.'' 82 FR at 3091. Thus, for each 
source it has selected for four-factor analysis,\24\ a State must 
consider a ``meaningful set'' of technically feasible control options 
for reducing emissions of visibility impairing pollutants. Id. at 3088. 
The 2019 Guidance provides that ``[a] State must reasonably pick and 
justify the measures that it will consider, recognizing that there is 
no statutory or regulatory requirement to consider all technically 
feasible measures or any particular measures. A range of technically 
feasible measures available to reduce emissions would be one way to 
justify a reasonable set.'' 2019 Guidance at 29.
---------------------------------------------------------------------------

    \23\ The CAA provides that, ``[i]n determining reasonable 
progress there shall be taken into consideration'' the four 
statutory factors. CAA 169A(g)(1). However, in addition to four-
factor analyses for selected sources, groups of sources, or source 
categories, a state may also consider additional emission reduction 
measures for inclusion in its long-term strategy, e.g., from other 
newly adopted, on-the-books, or on-the-way rules and measures for 
sources not selected for four-factor analysis for the second 
planning period.
    \24\ ``Each source'' or ``particular source'' is used here as 
shorthand. While a source-specific analysis is one way of applying 
the four factors, neither the statute nor the RHR requires states to 
evaluate individual sources. Rather, states have ``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.'' 82 FR at 
3088. However, not all approaches to grouping sources for four-
factor analysis are necessarily reasonable; the reasonableness of 
grouping sources in any particular instance will depend on the 
circumstances and the manner in which grouping is conducted. If it 
is feasible to establish and enforce different requirements for 
sources or subgroups of sources, and if relevant factors can be 
quantified for those sources or subgroups, then states should make a 
separate reasonable progress determination for each source or 
subgroup. 2021 Clarifications Memo at 7-8.
---------------------------------------------------------------------------

    EPA's 2021 Clarifications Memo provides further guidance on what 
constitutes a reasonable set of control options for consideration: ``A 
reasonable four-factor analysis will consider the full range of 
potentially reasonable options for reducing emissions.'' 2021 
Clarifications Memo at 7. In addition to add-on controls and other 
retrofits (i.e., new emissions reduction measures for sources), EPA 
explained that states should generally analyze efficiency improvements 
for sources' existing measures as control options in their four-factor 
analyses, as in many cases such improvements are reasonable given that 
they typically involve only additional operation and maintenance

[[Page 83344]]

costs. Additionally, the 2021 Clarifications Memo provides that states 
that have assumed a higher emissions rate than a source has achieved or 
could potentially achieve using its existing measures should also 
consider lower emissions rates as potential control options. That is, a 
State should consider a source's recent actual and projected emission 
rates to determine if it could reasonably attain lower emission rates 
with its existing measures. If so, the State should analyze the lower 
emission rate as a control option for reducing emissions. 2021 
Clarifications Memo at 7. The EPA's recommendations to analyze 
potential efficiency improvements and achievable lower emission rates 
apply to both sources that have been selected for four-factor analysis 
and those that have forgone a four-factor analysis on the basis of 
existing ``effective controls.'' See 2021 Clarifications Memo at 5, 10.
    After identifying a reasonable set of potential control options for 
the sources it has selected, a State then collects information on the 
four factors with regard to each option identified. The EPA has also 
explained that, in addition to the four statutory factors, states have 
flexibility under the CAA and RHR to reasonably consider visibility 
benefits as an additional factor alongside the four statutory 
factors.\25\ The 2019 Guidance provides recommendations for the types 
of information that can be used to characterize the four factors (with 
or without visibility), as well as ways in which states might 
reasonably consider and balance that information to determine which of 
the potential control options is necessary to make reasonable progress. 
See 2019 Guidance at 30-36. The 2021 Clarifications Memo contains 
further guidance on how states can reasonably consider modeled 
visibility impacts or benefits in the context of a four-factor 
analysis. 2021 Clarifications Memo at 12-13, 14-15. Specifically, the 
EPA explained that while visibility can reasonably be used when 
comparing and choosing between multiple reasonable control options, it 
should not be used to summarily reject controls that are reasonable 
given the four statutory factors. 2021 Clarifications Memo at 13. 
Ultimately, while states have discretion to reasonably weigh the 
factors and to determine what level of control is needed, Sec.  
51.308(f)(2)(i) provides that a State ``must include in its 
implementation plan a description of . . . how the four factors were 
taken into consideration in selecting the measure for inclusion in its 
long-term strategy.''
---------------------------------------------------------------------------

    \25\ See, e.g., Responses to Comments on Protection of 
Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016) (December 2016), Docket Number EPA-
HQ-OAR-2015-0531, U.S. Environmental Protection Agency at 186; 2019 
Guidance at 36-37.
---------------------------------------------------------------------------

    As explained above, Sec.  51.308(f)(2)(i) requires states to 
determine the emission reduction measures for sources that are 
necessary to make reasonable progress by considering the four factors. 
Pursuant to Sec.  51.308(f)(2), measures that are necessary to make 
reasonable progress towards the national visibility goal must be 
included in a state's long-term strategy and in its SIP.\26\ If the 
outcome of a four-factor analysis is a new, additional emission 
reduction measure for a source, that new measure is necessary to make 
reasonable progress towards remedying existing anthropogenic visibility 
impairment and must be included in the SIP. If the outcome of a four-
factor analysis is that no new measures are reasonable for a source, 
continued implementation of the source's existing measures is generally 
necessary to prevent future emission increases and thus to make 
reasonable progress towards the second part of the national visibility 
goal: preventing future anthropogenic visibility impairment. See CAA 
169A(a)(1). That is, when the result of a four-factor analysis is that 
no new measures are necessary to make reasonable progress, the source's 
existing measures are generally necessary to make reasonable progress 
and must be included in the SIP. However, there may be circumstances in 
which a State can demonstrate that a source's existing measures are not 
necessary to make reasonable progress. Specifically, if a State can 
demonstrate that a source will continue to implement its existing 
measures and will not increase its emissions rate, it may not be 
necessary to have those measures in the long-term strategy to prevent 
future emissions increases and future visibility impairment. The EPA's 
2021 Clarifications Memo provides further explanation and guidance on 
how states may demonstrate that a source's existing measures are not 
necessary to make reasonable progress. See 2021 Clarifications Memo at 
8-10. If the State can make such a demonstration, it need not include a 
source's existing measures in the long-term strategy or its SIP.
---------------------------------------------------------------------------

    \26\ States may choose to, but are not required to, include 
measures in their long-term strategies beyond just the emission 
reduction measures that are necessary for reasonable progress. See 
2021 Clarifications Memo at 16. For example, states with smoke 
management programs may choose to submit their smoke management 
plans to the EPA for inclusion in their SIPs but are not required to 
do so. See, e.g., 82 FR at 3108-09 (requirement to consider smoke 
management practices and smoke management programs under 40 CFR 
51.308(f)(2)(iv) does not require states to adopt such practices or 
programs into their SIPs, although they may elect to do so).
---------------------------------------------------------------------------

    As with source selection, the characterization of information on 
each of the factors is also subject to the documentation requirement in 
Sec.  51.308(f)(2)(iii). The reasonable progress analysis, including 
source selection, information gathering, characterization of the four 
statutory factors (and potentially visibility), balancing of the four 
factors, and selection of the emission reduction measures that 
represent reasonable progress, is a technically complex exercise, but 
also a flexible one that provides states with bounded discretion to 
design and implement approaches appropriate to their circumstances. 
Given this flexibility, Sec.  51.308(f)(2)(iii) plays an important 
function in requiring a State to document the technical basis for its 
decision making so that the public and the EPA can comprehend and 
evaluate the information and analysis the State relied upon to 
determine what emission reduction measures must be in place to make 
reasonable progress. The technical documentation must include the 
modeling, monitoring, cost, engineering, and emissions information on 
which the State relied to determine the measures necessary to make 
reasonable progress. This documentation requirement can be met through 
the provision of and reliance on technical analyses developed through a 
regional planning process, so long as that process and its output has 
been approved by all State participants. In addition to the explicit 
regulatory requirement to document the technical basis of their 
reasonable progress determinations, states are also subject to the 
general principle that those determinations must be reasonably moored 
to the statute.\27\ That is, a state's decisions about the emission 
reduction measures that are necessary to make reasonable progress must 
be consistent with the statutory goal of remedying existing and 
preventing future visibility impairment.
---------------------------------------------------------------------------

    \27\ See Arizona ex rel. Darwin v. U.S. EPA, 815 F.3d 519, 531 
(9th Cir. 2016); Nebraska v. U.S. EPA, 812 F.3d 662, 668 (8th Cir. 
2016); North Dakota v. EPA, 730 F.3d 750, 761 (8th Cir. 2013); 
Oklahoma v. EPA, 723 F.3d 1201, 1206, 1208-10 (10th Cir. 2013); cf. 
also Nat'l Parks Conservation Ass'n v. EPA, 803 F.3d 151, 165 (3d 
Cir. 2015); Alaska Dep't of Envtl. Conservation v. EPA, 540 U.S. 
461, 485, 490 (2004).
---------------------------------------------------------------------------

    The four statutory factors (and potentially visibility) are used to 
determine what emission reduction measures for selected sources must be 
included in a state's long-term strategy

[[Page 83345]]

for making reasonable progress. Additionally, the RHR at 40 CFR 
51.3108(f)(2)(iv) separately provides five ``additional factors'' \28\ 
that states must consider in developing their long-term strategies: (1) 
Emission reductions due to ongoing air pollution control programs, 
including measures to address reasonably attributable visibility 
impairment; (2) measures to reduce the impacts of construction 
activities; (3) source retirement and replacement schedules; (4) basic 
smoke management practices for prescribed fire used for agricultural 
and wildland vegetation management purposes and smoke management 
programs; and (5) the anticipated net effect on visibility due to 
projected changes in point, area, and mobile source emissions over the 
period addressed by the long-term strategy. The 2019 Guidance provides 
that a State may satisfy this requirement by considering these 
additional factors in the process of selecting sources for four-factor 
analysis, when performing that analysis, or both, and that not every 
one of the additional factors needs to be considered at the same stage 
of the process. See 2019 Guidance at 21. The EPA provided further 
guidance on the five additional factors in the 2021 Clarifications 
Memo, explaining that a State should generally not reject cost-
effective and otherwise reasonable controls merely because there have 
been emission reductions since the first planning period owing to other 
ongoing air pollution control programs or merely because visibility is 
otherwise projected to improve at Class I areas. Additionally, states 
generally should not rely on these additional factors to summarily 
assert that the State has already made sufficient progress and, 
therefore, no sources need to be selected or no new controls are needed 
regardless of the outcome of four-factor analyses. 2021 Clarifications 
Memo at 13.
---------------------------------------------------------------------------

    \28\ The five ``additional factors'' for consideration in 
section 51.308(f)(2)(iv) are distinct from the four factors listed 
in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states 
must consider and apply to sources in determining reasonable 
progress.
---------------------------------------------------------------------------

    Because the air pollution that causes regional haze crosses State 
boundaries, Sec.  51.308(f)(2)(ii) requires a State to consult with 
other states that also have emissions that are reasonably anticipated 
to contribute to visibility impairment in a given Class I area. 
Consultation allows for each State that impacts visibility in an area 
to share whatever technical information, analyses, and control 
determinations may be necessary to develop coordinated emission 
management strategies. This coordination may be managed through inter- 
and intra-RPO consultation and the development of regional emissions 
strategies; additional consultations between states outside of RPO 
processes may also occur. If a State, pursuant to consultation, agrees 
that certain measures (e.g., a certain emission limitation) are 
necessary to make reasonable progress at a Class I area, it must 
include those measures in its SIP. 40 CFR 51.308(f)(2)(ii)(A). 
Additionally, the RHR requires that states that contribute to 
visibility impairment at the same Class I area consider the emission 
reduction measures the other contributing states have identified as 
being necessary to make reasonable progress for their own sources. 40 
CFR 51.308(f)(2)(ii)(B). If a State has been asked to consider or adopt 
certain emission reduction measures, but ultimately determines those 
measures are not necessary to make reasonable progress, that State must 
document in its SIP the actions taken to resolve the disagreement. 40 
CFR 51.308(f)(2)(ii)(C). The EPA will consider the technical 
information and explanations presented by the submitting State and the 
State with which it disagrees when considering whether to approve the 
state's SIP. See Id.; 2019 Guidance at 53. Under all circumstances, a 
State must document in its SIP submission all substantive consultations 
with other contributing states. 40 CFR 51.308(f)(2)(ii)(C).

D. Reasonable Progress Goals

    Reasonable progress goals ``measure the progress that is projected 
to be achieved by the control measures states have determined are 
necessary to make reasonable progress based on a four-factor 
analysis.'' 82 FR at 3091. Their primary purpose is to assist the 
public and the EPA in assessing the reasonableness of states' long-term 
strategies for making reasonable progress towards the national 
visibility goal. See 40 CFR 51.308(f)(3)(iii)-(iv). States in which 
Class I areas are located must establish two RPGs, both in deciviews--
one representing visibility conditions on the clearest days and one 
representing visibility on the most anthropogenically impaired days--
for each area within their borders. 40 CFR 51.308(f)(3)(i). The two 
RPGs are intended to reflect the projected impacts, on the two sets of 
days, of the emission reduction measures the State with the Class I 
area, as well as all other contributing states, have included in their 
long-term strategies for the second implementation period.\29\ The RPGs 
also account for the projected impacts of implementing other CAA 
requirements, including non-SIP based requirements. Because RPGs are 
the modeled result of the measures in states' long-term strategies (as 
well as other measures required under the CAA), they cannot be 
determined before states have conducted their four-factor analyses and 
determined the control measures that are necessary to make reasonable 
progress. See 2021 Clarifications Memo at 6.
---------------------------------------------------------------------------

    \29\ RPGs are intended to reflect the projected impacts of the 
measures all contributing states include in their long-term 
strategies. However, due to the timing of analyses and of control 
determinations by other states, other on-going emissions changes, a 
particular state's RPGs may not reflect all control measures and 
emissions reductions that are expected to occur by the end of the 
implementation period. The 2019 Guidance provides recommendations 
for addressing the timing of RPG calculations when states are 
developing their long-term strategies on disparate schedules, as 
well as for adjusting RPGs using a post-modeling approach. 2019 
Guidance at 47-48.
---------------------------------------------------------------------------

    For the second implementation period, the RPGs are set for 2028. 
Reasonable progress goals are not enforceable targets, 40 CFR 
51.308(f)(3)(iii); rather, they ``provide a way for the states to check 
the projected outcome of the [long-term strategy] against the goals for 
visibility improvement.'' 2019 Guidance at 46. While states are not 
legally obligated to achieve the visibility conditions described in 
their RPGs, Sec.  51.308(f)(3)(i) requires that ``[t]he long-term 
strategy and the reasonable progress goals must provide for an 
improvement in visibility for the most impaired days since the baseline 
period and ensure no degradation in visibility for the clearest days 
since the baseline period.'' Thus, states are required to have emission 
reduction measures in their long-term strategies that are projected to 
achieve visibility conditions on the most impaired days that are better 
than the baseline period and shows no degradation on the clearest days 
compared to the clearest days from the baseline period. The baseline 
period for the purpose of this comparison is the baseline visibility 
condition--the annual average visibility condition for the period 2000-
2004. See 40 CFR 51.308(f)(1)(i), 82 FR at 3097-98.
    So that RPGs may also serve as a metric for assessing the amount of 
progress a State is making towards the national visibility goal, the 
RHR requires states with Class I areas to compare the 2028 RPG for the 
most impaired days to the corresponding point on the URP line 
(representing visibility conditions in 2028 if visibility

[[Page 83346]]

were to improve at a linear rate from conditions in the baseline period 
of 2000-2004 to natural visibility conditions in 2064). If the most 
impaired days RPG in 2028 is above the URP (i.e., if visibility 
conditions are improving more slowly than the rate described by the 
URP), each State that contributes to visibility impairment in the Class 
I area must demonstrate, based on the four-factor analysis required 
under 40 CFR 51.308(f)(2)(i), that no additional emission reduction 
measures would be reasonable to include in its long-term strategy. 40 
CFR 51.308(f)(3)(ii). To this end, 40 CFR 51.308(f)(3)(ii) requires 
that each State contributing to visibility impairment in a Class I area 
that is projected to improve more slowly than the URP provide ``a 
robust demonstration, including documenting the criteria used to 
determine which sources or groups [of] sources were evaluated and how 
the four factors required by paragraph (f)(2)(i) were taken into 
consideration in selecting the measures for inclusion in its long-term 
strategy.'' The 2019 Guidance provides suggestions about how such a 
``robust demonstration'' might be conducted. See 2019 Guidance at 50-
51.
    The 2017 RHR, 2019 Guidance, and 2021 Clarifications Memo also 
explain that projecting an RPG that is on or below the URP based on 
only on-the-books and/or on-the-way control measures (i.e., control 
measures already required or anticipated before the four-factor 
analysis is conducted) is not a ``safe harbor'' from the CAA's and 
RHR's requirement that all states must conduct a four-factor analysis 
to determine what emission reduction measures constitute reasonable 
progress. The URP is a planning metric used to gauge the amount of 
progress made thus far and the amount left before reaching natural 
visibility conditions. However, the URP is not based on consideration 
of the four statutory factors and therefore cannot answer the question 
of whether the amount of progress being made in any particular 
implementation period is ``reasonable progress.'' See 82 FR at 3093, 
3099-3100; 2019 Guidance at 22; 2021 Clarifications Memo at 15-16.

E. Monitoring Strategy and Other State Implementation Plan Requirements

    Section 51.308(f)(6) requires states to have certain strategies and 
elements in place for assessing and reporting on visibility. Individual 
requirements under this subsection apply either to states with Class I 
areas within their borders, states with no Class I areas but that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any Class I area, or both. A State with Class I areas within its 
borders must submit with its SIP revision a monitoring strategy for 
measuring, characterizing, and reporting regional haze visibility 
impairment that is representative of all Class I areas within the 
State. SIP revisions for such states must also provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess visibility conditions in Class I areas, as well as reporting of 
all visibility monitoring data to the EPA at least annually. Compliance 
with the monitoring strategy requirement may be met through a state's 
participation in the Interagency Monitoring of Protected Visual 
Environments (IMPROVE) monitoring network, which is used to measure 
visibility impairment caused by air pollution at the 156 Class I areas 
covered by the visibility program. 40 CFR 51.308(f)(6), (f)(6)(i), 
(f)(6)(iv). The IMPROVE monitoring data is used to determine the 20% 
most anthropogenically impaired and 20% clearest sets of days every 
year at each Class I area and tracks visibility impairment over time.
    All states' SIPs must provide for procedures by which monitoring 
data and other information are used to determine the contribution of 
emissions from within the State to regional haze visibility impairment 
in affected Class I areas. 40 CFR 51.308(f)(6)(ii), (iii). Section 
51.308(f)(6)(v) further requires that all states' SIPs provide for a 
statewide inventory of emissions of pollutants that are reasonably 
anticipated to cause or contribute to visibility impairment in any 
Class I area; the inventory must include emissions for the most recent 
year for which data are available and estimates of future projected 
emissions. States must also include commitments to update their 
inventories periodically. The inventories themselves do not need to be 
included as elements in the SIP and are not subject to EPA review as 
part of the Agency's evaluation of a SIP revision.\30\ All states' SIPs 
must also provide for any other elements, including reporting, 
recordkeeping, and other measures, that are necessary for states to 
assess and report on visibility. 40 CFR 51.308(f)(6)(vi). Per the 2019 
Guidance, a State may note in its regional haze SIP that its compliance 
with the Air Emissions Reporting Rule (AERR) in 40 CFR part 51 subpart 
A satisfies the requirement to provide for an emissions inventory for 
the most recent year for which data are available. To satisfy the 
requirement to provide estimates of future projected emissions, a State 
may explain in its SIP how projected emissions were developed for use 
in establishing RPGs for its own and nearby Class I areas.\31\
---------------------------------------------------------------------------

    \30\ See ``Step 8: Additional requirements for regional haze 
SIPs'' in 2019 Guidance at 55.
    \31\ Id.
---------------------------------------------------------------------------

    Separate from the requirements related to monitoring for regional 
haze purposes under 40 CFR 51.308(f)(6), the RHR also contains a 
requirement at Sec.  51.308(f)(4) related to any additional monitoring 
that may be needed to address visibility impairment in Class I areas 
from a single source or a small group of sources. This is called 
``reasonably attributable visibility impairment.'' \32\ Under this 
provision, if the EPA or the FLM of an affected Class I area has 
advised a State that additional monitoring is needed to assess 
reasonably attributable visibility impairment, the State must include 
in its SIP revision for the second implementation period an appropriate 
strategy for evaluating such impairment.
---------------------------------------------------------------------------

    \32\ The EPA's visibility protection regulations define 
``reasonably attributable visibility impairment'' as ``visibility 
impairment that is caused by the emission of air pollutants from 
one, or a small number of sources.'' 40 CFR 51.301.
---------------------------------------------------------------------------

F. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires a state's regional haze SIP revision 
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through 
(5) so that the plan revision due in 2021 will serve also as a progress 
report addressing the period since submission of the progress report 
for the first implementation period. The regional haze progress report 
requirement is designed to inform the public and the EPA about a 
state's implementation of its existing long-term strategy and whether 
such implementation is in fact resulting in the expected visibility 
improvement. See 81 FR 26942, 26950 (May 4, 2016); 82 FR at 3119 
(January 10, 2017). To this end, every state's SIP revision for the 
second implementation period is required to describe the status of 
implementation of all measures included in the state's long-term 
strategy, including BART and reasonable progress emission reduction 
measures from the first implementation period, and the resulting 
emissions reductions. 40 CFR 51.308(g)(1) and (2).

[[Page 83347]]

    A core component of the progress report requirements is an 
assessment of changes in visibility conditions on the clearest and most 
impaired days. For second implementation period progress reports, Sec.  
51.308(g)(3) requires states with Class I areas within their borders to 
first determine current visibility conditions for each area on the most 
impaired and clearest days, 40 CFR 51.308(g)(3)(i)(B), and then to 
calculate the difference between those current conditions and baseline 
(2000-2004) visibility conditions to assess progress made to date. See 
40 CFR 51.308(g)(3)(ii)(B). States must also assess the changes in 
visibility impairment for the most impaired and clearest days since 
they submitted their first implementation period progress reports. See 
40 CFR 51.308(g)(3)(iii)(B), (f)(5). Since different states submitted 
their first implementation period progress reports at different times, 
the starting point for this assessment will vary State by State.
    Similarly, states must provide analyses tracking the change in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the State over the period since they 
submitted their first implementation period progress reports. See 40 
CFR 51.308(g)(4), (f)(5). Changes in emissions should be identified by 
the type of source or activity. Section 51.308(g)(5) also addresses 
changes in emissions since the period addressed by the previous 
progress report and requires states' SIP revisions to include an 
assessment of any significant changes in anthropogenic emissions within 
or outside the State. This assessment must explain whether these 
changes in emissions were anticipated and whether they have limited or 
impeded progress in reducing emissions and improving visibility 
relative to what the State projected based on its long-term strategy 
for the first implementation period.

G. Requirements for State and Federal Land Manager Coordination

    Clean Air Act section 169A(d) requires that before a State holds a 
public hearing on a proposed regional haze SIP revision, it must 
consult with the appropriate FLM or FLMs; pursuant to that 
consultation, the State must include a summary of the FLMs' conclusions 
and recommendations in the notice to the public. Consistent with this 
statutory requirement, the RHR also requires that states ``provide the 
[FLM] with an opportunity for consultation, in person and at a point 
early enough in the State's policy analyses of its long-term strategy 
emission reduction obligation so that information and recommendations 
provided by the [FLM] can meaningfully inform the State's decisions on 
the long-term strategy.'' 40 CFR 51.308(i)(2). Consultation that occurs 
120 days prior to any public hearing or public comment opportunity will 
be deemed ``early enough,'' but the RHR provides that in any event the 
opportunity for consultation must be provided at least 60 days before a 
public hearing or comment opportunity. This consultation must include 
the opportunity for the FLMs to discuss their assessment of visibility 
impairment in any Class I area and their recommendations on the 
development and implementation of strategies to address such 
impairment. 40 CFR 51.308(i)(2). For the EPA to evaluate whether FLM 
consultation meeting the requirements of the RHR has occurred, the SIP 
submission should include documentation of the timing and content of 
such consultation. The SIP revision submitted to the EPA must also 
describe how the State addressed any comments provided by the FLMs. 40 
CFR 51.308(i)(3). Finally, a SIP revision must provide procedures for 
continuing consultation between the State and FLMs regarding the 
state's visibility protection program, including development and review 
of SIP revisions, five-year progress reports, and the implementation of 
other programs having the potential to contribute to impairment of 
visibility in Class I areas. 40 CFR 51.308(i)(4).

IV. The EPA's Evaluation of Texas's Regional Haze Submission for the 
Second Implementation Period

A. Background on Texas's First Implementation Period SIP Submission

    Texas submitted its regional haze SIP for the first implementation 
period to the EPA on March 31, 2009. The EPA issued a limited 
disapproval of Texas's RH SIP on June 7, 2012, due to its reliance on 
the Clean Air Interstate Rule (CAIR) to address BART requirements for 
Texas electric generating units (EGUs).\33\ The EPA proposed a rule to 
partially approve and partially disapprove Texas's SIP on December 16, 
2014; \34\ however, due to a related ruling from the United States 
Court of Appeals for the District of Columbia Circuit (D.C. 
Circuit),\35\ the EPA could not finalize the December 2014 proposal in 
its entirety. As such, the EPA's obligations for the first 
implementation period for Texas's regional haze SIP were addressed in 
two separate actions. One action, finalized on January 5, 2016, 
addressed the regional haze requirements in Texas except for BART 
requirements for EGUs.\36\ The second action, finalized on October 17, 
2017, and affirmed on August 12, 2020, addressed BART requirements for 
Texas EGUs.\37\ The EPA has convened separate reconsideration 
proceedings for both actions.\38\ While these proceedings remain 
ongoing, they do not interfere with the EPA's statutory obligation to 
take action on Texas's SIP revision for the second implementation 
period.\39\
---------------------------------------------------------------------------

    \33\ 77 FR 33642 (June 7, 2012).
    \34\ 79 FR 74818 (Dec. 16, 2014).
    \35\ EME Homer City Generation, L.P v. EPA, 795 F.3d 118 (D.C. 
Cir. 2015).
    \36\ 81 FR 296 (Jan. 5, 2016). In July 2016, the 5th Circuit 
Court of Appeals issued a stay of the action. Texas v. EPA, 829 F.3d 
405 (5th Cir. 2016). Subsequent to the stay opinion, the EPA 
requested and the court granted EPA's motion for a partial voluntary 
remand.
    \37\ See 82 FR 48324 (Oct. 17, 2017); 85 FR 49170 (Aug. 12, 
2020).
    \38\ See 88 FR 28918 (May 4, 2023); 88 FR 48152 (July 26, 2023).
    \39\ EPA is not precluded from acting on a submitted second 
planning period SIP revision because reconsideration proceedings on 
first planning period actions remains ongoing. All states had an 
obligation to submit second planning period SIP revisions by July 
31, 2021, regardless of the status of first planning period 
obligations. After a second planning period SIP revision is 
submitted to EPA for review, EPA is statutorily required to review 
and act on that plan within 12 months of the submittal being deemed 
complete. See CAA 110(k)(1); 42 U.S.C. 7410(k)(1). Even with ongoing 
work on the second planning period, EPA will continue to work to 
address first planning period obligations.
---------------------------------------------------------------------------

    The requirements for regional haze SIPs for the first 
implementation period are contained in 40 CFR 51.308(d) and (e). 
Pursuant to 40 CFR 51.308(g), Texas was also responsible for submitting 
a five-year progress report as a SIP revision for the first 
implementation period, which it did in 2014.\40\
---------------------------------------------------------------------------

    \40\ The EPA has not yet taken action on the progress report 
SIP.
---------------------------------------------------------------------------

B. Texas's Second Implementation Period SIP Submission and the EPA's 
Evaluation

    In accordance with CAA sections 169A and the RHR at 40 CFR 
51.308(f) and (i), on July 20, 2021, Texas submitted a SIP revision to 
address its regional haze obligations for the second implementation 
period, which runs through 2028. Texas made its 2021 Regional Haze SIP 
submission available for public comment on October 9, 2020. Texas 
received and responded to public comments and included the comments and 
responses to those comments in their submission.
    The following sections describe Texas's RH SIP submission, Texas's 
assessment of progress made since the first implementation period in 
reducing emissions of visibility impairing pollutants, and the 
visibility improvement progress at its Class I areas

[[Page 83348]]

and nearby Class I areas. This notice also contains EPA's evaluation of 
Texas's submission against the requirements of the CAA and RHR for the 
second implementation period of the regional haze program.

C. Identification of Class I Areas

    Section 169A(b)(2) of the CAA requires each State in which any 
Class I area is located or ``the emissions from which may reasonably be 
anticipated to cause or contribute to any impairment of visibility'' in 
a Class I area to have a plan for making reasonable progress toward the 
national visibility goal. The RHR implements this statutory requirement 
at 40 CFR 51.308(f), which provides that each state's plan ``must 
address regional haze in each mandatory Class I Federal area located 
within the State and in each mandatory Class I Federal area located 
outside the State that may be affected by emissions from within the 
State,'' and (f)(2), which requires each state's plan to include a 
long-term strategy that addresses regional haze in such Class I areas.
    The EPA explained in the 1999 RHR preamble that the CAA section 
169A(b)(2) requirement that states submit SIPs to address visibility 
impairment establishes ``an `extremely low triggering threshold' in 
determining which States should submit SIPs for regional haze.'' \41\ 
In concluding that each of the contiguous 48 States and the District of 
Columbia meet this threshold,\42\ the EPA relied on ``a large body of 
evidence demonstrat[ing] that long-range transport of fine PM 
contributes to regional haze,'' \43\ including modeling studies that 
``preliminarily demonstrated that each State not having a Class I area 
had emissions contributing to impairment in at least one downwind Class 
I area.'' \44\ In addition to the technical evidence supporting a 
conclusion that each State contributes to existing visibility 
impairment, the EPA also explained that the second half of the national 
visibility goal--preventing future visibility impairment--requires 
having a framework in place to address future growth in visibility 
impairing emissions and makes it inappropriate to ``establish criteria 
for excluding States or geographic areas from consideration as 
potential contributors to regional haze visibility impairment.'' \45\ 
Thus, the EPA concluded that the agency's ``statutory authority and the 
scientific evidence are sufficient to require all States to develop 
regional haze SIPs to ensure the prevention of any future impairment of 
visibility, and to conduct further analyses to determine whether 
additional control measures are needed to ensure reasonable progress in 
remedying existing impairment in downwind Class I areas.'' \46\ The 
EPA's 2017 revisions to the RHR did not disturb this conclusion.\47\
---------------------------------------------------------------------------

    \41\ 64 FR at 35721.
    \42\ The EPA determined that ``there is more than sufficient 
evidence to support our conclusion that emissions from each of the 
48 contiguous States may reasonably be anticipated to cause or 
contribute to visibility impairment in a Class I area.'' 64 FR at 
35721. Hawaii, Alaska, and the U.S. Virgin Islands must also submit 
regional haze SIPs because they contain Class I areas.
    \43\ Id.
    \44\ Id. at 35722.
    \45\ Id. at 35721.
    \46\ Id. at 35722.
    \47\ See 82 FR at 3094.
---------------------------------------------------------------------------

1. Texas Class I Areas
    Texas has two mandatory Class I areas within its borders, both of 
which are located in west Texas. Big Bend National Park (Big Bend) is 
in Brewster County and borders the Rio Grande and Mexico. Guadalupe 
Mountains National Park (Guadalupe Mountains) is in Culberson County 
and borders New Mexico. Both are managed by the National Park Service.
    Big Bend was authorized as a national park on June 20, 1935, and 
established and signed into law on June 12, 1944, as the nation's 27th 
national park. Big Bend encompasses an area of 801,163 acres, entirely 
within Brewster County, Texas. For more than 1,000 miles, the Rio 
Grande forms the boundary between Mexico and the U.S., with Big Bend 
administering approximately 118 miles along the international boundary. 
The park gets its name from the course of the Rio Grande, which makes a 
great bend from a southeasterly to northerly direction in the western 
portion of Texas. Big Bend has national significance as the largest 
protected area of Chihuahuan Desert in the continental U.S. The park 
contains river, desert, and mountain environments.
    Guadalupe Mountains was established as a national park on September 
30, 1972, and contains Guadalupe Peak, the highest point in Texas at 
8,749 feet, and El Capitan, a 1,000 foot-high limestone cliff. 
Guadalupe Mountains are also part of a mostly buried 400-mile long U-
shaped fossil reef complex, Capitan Reef. The park covers more than 
86,000 acres and is in the same mountain range of Carlsbad Caverns 
National Park, which is located about 40 miles to the northeast in New 
Mexico. Guadalupe Mountains is also located in the Chihuahuan Desert. 
The park is surrounded by the South Plains to the east and north, 
Delaware Mountains to the south, and Sacramento Mountains to the west.
2. Identification of Impacted Class I Areas Outside the State
    In addition to the two Class I areas in Texas, the TCEQ conducted 
area of influence analyses (AOIs) paired with emissions-over-distance 
(Q/d) analyses for 11 Class I areas in other states including 
Louisiana, Arkansas, Colorado, Missouri, Oklahoma, and New Mexico. The 
AOIs were generated using ammonium sulfate and ammonium nitrate 
extinction-weighted residence times (EWRT).\48\ The Class I areas 
included in the analysis from Texas and neighboring states are 
presented in table 1, which is taken from table 7-3: Class I Areas 
included in AOI Analyses of the 2021 Texas Regional Haze Plan.\49\
---------------------------------------------------------------------------

    \48\ 2021 Texas Regional Haze Plan at 7-6. Extinction-weighted 
residence time is calculated from the time that a particular back-
trajectory from a Class I area spent in the grid square containing 
the individual emission source of interest (residence time) weighted 
by the extinction coefficient for the visibility precursor (sulfate 
and nitrate).
    \49\ For the purposes of the AOI analysis, Carlsbad Caverns was 
represented by data from the Guadalupe Mountains National Park 
monitor. See 2021 Texas Regional Haze Plan at 1-5.

              Table 1--Class I Areas Included in AOI Analyses of the 2021 Texas Regional Haze Plan
----------------------------------------------------------------------------------------------------------------
               Site                          Code                State         County     Latitude    Longitude
----------------------------------------------------------------------------------------------------------------
Big Bend National Park............  BIBE1................  TX                    48043      29.3027     -103.178
Breton Island.....................  BRIS1................  LA                    22075     30.10863    -89.76168
Caney Creek.......................  CACR1................  AR                    05113      34.4544     -94.1429
Great Sand Dunes..................  GRSA1................  CO                    08003      37.7249    -105.5185
Guadalupe Mountains National Park.  GUMO.................  TX                    48109       31.833    -104.8094
Hercules-Glades...................  HEG1.................  MO                    29213      36.6138     -92.9221
Mingo.............................  MING1................  MO                    29207      36.9717     -90.1432

[[Page 83349]]

 
Rocky Mountain National Park......  ROMO1................  CO                    08069      40.2783    -105.5457
Salt Creek........................  SACR1................  NM                    35005      33.4598    -104.4042
Upper Buffalo Wilderness..........  UPBO1................  AR                    05101      35.8258      -93.203
Wheeler Peak......................  WHPE1................  NM                    35055      36.5854      -105.42
White Mountain....................  WHIT1................  NM                    35027      33.4687    -105.5349
Wichita Mountains.................  WIMO1................  OK                    40031      34.7323      -98.713
----------------------------------------------------------------------------------------------------------------

    As explained above, the EPA concluded in the 1999 RHR that ``all 
[s]tates contain sources whose emissions are reasonably anticipated to 
contribute to regional haze in a Class I area,'' and this determination 
was not changed in the 2017 RHR.\50\ Critically, the statute and 
regulation both require that the cause-or-contribute assessment 
consider all emissions of visibility impairing pollutants from a State, 
as opposed to emissions of a particular pollutant or emissions from a 
certain set of sources. Consistent with these requirements, the 2019 
Guidance makes it clear that ``all types of anthropogenic sources are 
to be included in the determination'' of whether a state's emissions 
are reasonably anticipated to result in any visibility impairment.\51\
---------------------------------------------------------------------------

    \50\ 64 FR at 35721.
    \51\ 2019 Guidance at 8.
---------------------------------------------------------------------------

    While Texas identified Class I areas within and outside of the 
State that are potentially impacted by Texas sources, Texas did not 
conduct an AOI analysis for the Bosque del Apache Class I area.\52\ 
Texas justifies this decision based on ``past SIP and FIP 
documentation'' but provides no additional context or explanation of 
why that decision remains appropriate for this planning period.\53\ In 
contrast, Texas's CAMx PSAT \54\ modeling identified Bosque del Apache 
as having impacts from Texas sources. According to Texas's PSAT 
modeling, Texas sources contribute over seven percent of the total 
visibility impairment at Bosque del Apache.\55\ Specifically, the 2021 
Texas Regional Haze Plan identifies that the influence due to 
particulate sulfate from Texas sources is more than five times the 
influence of New Mexico sources, and the influence due to particulate 
nitrate from Texas sources is nearly twice the influence of New Mexico 
sources.\56\ Thus, Texas's PSAT modeling suggests that emissions from 
Texas sources are reasonably anticipated to contribute to visibility 
impairment at the Bosque del Apache Class I area given the low 
threshold for visibility impact on Class I areas discussed 
previously.\57\ Therefore, Texas did not complete its obligation under 
40 CFR 51.308(f), which provides that each state's plan ``must address 
regional haze in each mandatory Class I Federal area located within the 
State and in each mandatory Class I Federal area located outside the 
State that may be affected by emissions from within the State,'' and 
(f)(2), which requires each state's plan to include a long-term 
strategy that addresses regional haze in such Class I areas.
---------------------------------------------------------------------------

    \52\ Texas also did not conduct an AOI analysis for the 
Bandelier Class I area for the same reasons provided for Bosque del 
Apache.
    \53\ 2021 Texas Regional Haze Plan, appendix A at 19 of 227; 
2021 Texas Regional Haze Plan, Response to Comments at 460 of 653.
    \54\ Comprehensive Air quality Model with extensions (CAMx) 
Particulate Source Apportionment Technique (PSAT). CAMx PSAT is 
capable of tracking source category emissions and separate source 
regions for certain PM species and precursor emissions. We discuss 
this further in the Technical Support Document (TSD) for this 
action, included in the docket.
    \55\ 2021 Texas Regional Haze Plan, appendix A at 26 of 227.
    \56\ See 2021 Texas Regional Haze Plan, table 8-41 at 8-53; and 
2021 Texas Regional Haze Plan, appendix F at F-59 to F-61.
    \57\ 2021 Texas Regional Haze Plan, appendix F at F-36.
---------------------------------------------------------------------------

D. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    Section 51.308(f)(1) requires states to determine the following for 
``each mandatory Class I Federal area located within the State'': 
baseline visibility conditions for the most impaired and clearest days, 
natural visibility conditions for the most impaired and clearest days, 
progress to date for the most impaired and clearest days, the 
differences between current visibility conditions and natural 
visibility conditions, and the URP. This section also provides the 
option for states to propose adjustments to the URP line for a Class I 
area to account for visibility impacts from anthropogenic sources 
outside the United States and/or the impacts from wildland prescribed 
fires that were conducted for certain, specified objectives.\58\
---------------------------------------------------------------------------

    \58\ 40 CFR 51.308(f)(1)(vi)(B).
---------------------------------------------------------------------------

    In Chapter 4 of the 2021 Texas Regional Haze Plan, Texas determines 
and presents the baseline, natural, and current visibility conditions 
for both the 20 percent most anthropogenically impaired days and the 20 
percent clearest days for the State's two Class I Areas consistent with 
the EPA's RHR and guidance. In the 2021 Texas Regional Haze Plan, the 
TCEQ used visibility data from IMPROVE monitoring sites to calculate 
baseline visibility conditions. Consistent with the RHR, Texas 
calculated baseline visibility based on data from 2000-2004. For Big 
Bend specifically, baseline visibility conditions are based on valid 
data for 2001 through 2004 because 2000 did not meet completeness 
criteria.\59\ Baseline visibility indices for Big Bend and Guadalupe 
Mountains are presented in the 2021 Texas Regional Haze Plan in table 
4-4. In our review, we identified that the information provided by 
Texas in Chapter 4 of its 2021 Regional Haze Plan as to the baseline 
and current conditions on the 20 percent clearest days is inconsistent 
with the IMPROVE monitoring data and information presented in Chapter 
8. Based on the information in table 8-42 of the 2021 Regional Haze 
Plan, Texas identifies the correct data set for where this information 
is located but presents the incorrect data in Chapter 4. Based on the 
data source that Texas identified in Chapter 8, we present information 
in tables 2 and 4 consistent with information in Chapter 8 of its Plan 
and the IMPROVE monitoring data.\60\
---------------------------------------------------------------------------

    \59\ See 2021 Texas Regional Haze Plan at 4-4.
    \60\ https://views.cira.colostate.edu/fed/. See also 2020 Data 
Completeness Memo, table 1.

[[Page 83350]]



           Table 2--Estimate of Baseline Visibility Conditions (2000-2004) for Class I Areas in Texas
----------------------------------------------------------------------------------------------------------------
                                                                Most impaired haze index    Clearest haze index
                        Class I area                                      (dv)                      (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend....................................................                        15.57                   5.78
Guadalupe Mountains.........................................                        14.60                   5.92
----------------------------------------------------------------------------------------------------------------

    Using the revised IMPROVE algorithm \61\ and the methodology 
described in the 2018 Visibility Tracking Guidance, the TCEQ determined 
natural visibility conditions for Big Bend and Guadalupe Mountains, 
presented in table 4-3 of the 2021 Texas Regional Haze Plan, and 
included in the following table 3.
---------------------------------------------------------------------------

    \61\ Marc Pitchford et al., Revised Algorithm for Estimating 
Light Extinction from IMPROVE Particle Speciation Data, j. Air & 
waste mgmt. Ass'n 1326, 1326-1336 (2007), https://doi.org/10.3155/1047-3289.57.11.1326.

                  Table 3--Estimate of Natural Visibility Conditions for Class I Areas in Texas
----------------------------------------------------------------------------------------------------------------
                                                                Most impaired haze index    Clearest haze index
                        Class I area                                      (dv)                      (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend....................................................                         5.33                   1.62
Guadalupe Mountains.........................................                         4.83                   0.99
----------------------------------------------------------------------------------------------------------------

    The current visibility conditions, which are based on 2014-2018 
monitoring data, are presented in the 2021 Texas Regional Haze Plan in 
table 4-5 with corrected values included in the following table 4.

            Table 4--Estimate of Current Visibility Conditions (2014-2018) for Class I Areas in Texas
----------------------------------------------------------------------------------------------------------------
                                                                Most impaired haze index    Clearest haze index
                        Class I area                                      (dv)                      (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend....................................................                        14.06                   5.17
Guadalupe Mountains.........................................                        12.64                   4.73
----------------------------------------------------------------------------------------------------------------

    While the 2021 Texas Regional Haze Plan does not specifically 
present the differences between current visibility conditions and 
natural visibility conditions as well as the progress to date, we 
include these calculations using the corrected information in tables 5 
and 6.

                                            Table 5--Progress to Date
                              (Differences Between Baseline and Current Conditions)
----------------------------------------------------------------------------------------------------------------
                        Class I area                               Most impaired (dv)        Clearest haze (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend....................................................                         1.51                   0.61
Guadalupe Mountains.........................................                         1.96                   1.19
----------------------------------------------------------------------------------------------------------------


                           Table 6--Differences Between Current and Natural Conditions
----------------------------------------------------------------------------------------------------------------
                        Class I area                               Most impaired (dv)        Clearest haze (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend....................................................                         8.73                   3.55
Guadalupe Mountains.........................................                         7.81                   3.74
----------------------------------------------------------------------------------------------------------------

    The Regional Haze Rule allows states the option to adjust the 2064 
glidepath endpoint to account for both international anthropogenic and 
certain prescribed fire impacts at Class I areas. In the EPA's 
September 2019 Availability of Modeling Data and Associated Technical 
Support Document for the EPA's Updated 2028 Visibility Air Quality 
Modeling memorandum \62\ (EPA 2019 Modeling TSD), the EPA used 2028 
modeling results to quantify the international and prescribed fire 
impacts at Class I areas on the 20% most anthropogenically impaired 
days. Texas used its own CAMx modeling results to adjust the URP to 
account for international anthropogenic emissions consistent with the 
approach used by the EPA in the TSD associated with the EPA's Updated 
2028 Visibility Air Quality Modeling memorandum. Texas's adjusted URP 
for Big Bend and Guadalupe Mountains are presented in Figures 8-28 and 
8-29 of its 2021 Texas

[[Page 83351]]

Regional Haze Plan.\63\ Texas's adjusted URP in 2028 on the 20% most 
impaired visibility days is 14.38 deciviews for Big Bend and 12.81 for 
Guadalupe Mountains.\64\ These values for Big Bend and Guadalupe 
Mountains are within the range of 2028 adjusted glidepath values 
provided for in the EPA 2019 Modeling TSD.\65\
---------------------------------------------------------------------------

    \62\ Availability of Modeling Data and Associated Technical 
Support Document for the EPA's Updated 2028 Visibility Air Quality 
Modeling. https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling. The EPA Office of Air 
Quality Planning and Standards, Research Triangle Park (Sep. 19, 
2019).
    \63\ After Texas adjusted the glidepath endpoint to account for 
contributions from international anthropogenic emissions, one site 
(Salt Creek, NM) was projected to be above the adjusted URP. The EPA 
2019 Modeling TSD also had Salt Creek above the adjusted glidepath.
    \64\ 2021 Texas Regional Haze Plan, table 8-43 at 8-59 and table 
8-46 at 8-67.
    \65\ EPA 2019 Modeling TSD at 54, 56, and table 5-2 at 59.
---------------------------------------------------------------------------

    The EPA finds that the visibility condition calculations for the 
two Texas Class I Areas meet the requirements of 40 CFR 51.308(f)(1). 
Therefore, the EPA proposes to approve the portions of the 2021 Texas 
Regional Haze Plan relating to 40 CFR 51.308(f)(1).

E. Long-Term Strategy for Regional Haze

    Each State having a Class I area within its borders or emissions 
that may affect visibility in a Class I area must develop a long-term 
strategy for making reasonable progress towards the national visibility 
goal.\66\ As explained in the Background section of this notice, 
reasonable progress is achieved when all states contributing to 
visibility impairment in a Class I area are implementing the measures 
determined--through application of the four statutory factors to 
sources of visibility impairing pollutants--to be necessary to make 
reasonable progress.\67\ Each state's long-term strategy must include 
the enforceable emission limitations, compliance schedules, and other 
measures that are necessary to make reasonable progress.\68\ All new 
(i.e., additional) measures that are the outcome of four-factor 
analyses are necessary to make reasonable progress and must be in the 
long-term strategy. If the outcome of a four-factor analysis and other 
measures necessary to make reasonable progress is that no new measures 
are reasonable for a source, that source's existing measures are 
necessary to make reasonable progress, unless the State can demonstrate 
that the source will continue to implement those measures and will not 
increase its emission rate. Existing measures that are necessary to 
make reasonable progress must also be in the long-term strategy. In 
developing its long-term strategies, a State must also consider the 
five additional factors in Sec.  51.308(f)(2)(iv). As part of its 
reasonable progress determinations, the State must describe the 
criteria used to determine which sources or group of sources were 
evaluated (i.e., subjected to four-factor analysis) for the second 
implementation period and how the four factors were taken into 
consideration in selecting the emission reduction measures for 
inclusion in the long-term strategy.\69\
---------------------------------------------------------------------------

    \66\ CAA 169A(b)(2)(B).
    \67\ 40 CFR 51.308(f)(2)(i).
    \68\ 40 CFR 51.308(f)(2).
    \69\ 40 CFR 51.308(f)(2)(i), (iii).
---------------------------------------------------------------------------

1. Source Selection
a. Overview of Texas's Source Selection
    Under 40 CFR 51.308(f)(2)(i), states must evaluate and determine 
the emission reduction measures that are necessary to make reasonable 
progress by considering 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 
anthropogenic source of visibility impairment.\70\ In doing so, states 
should consider evaluating major and minor stationary sources or groups 
of sources, mobile sources, and area sources as part of their long-term 
strategy for regional haze. Furthermore, the State must include in its 
implementation plan a description of the criteria it used to determine 
which sources or groups of sources it evaluated. States may rely on 
technical information developed by the RPOs of which they are members 
to select sources for four-factor analysis and to conduct that 
analysis, as well as to satisfy the documentation requirements under 40 
CFR 51.308(f)(2). Texas, however, conducted its own analysis separate 
from CenSARA's analysis to select sources for further evaluation using 
the four statutory factors.
---------------------------------------------------------------------------

    \70\ See also CAA 169A(g)(1).
---------------------------------------------------------------------------

    Texas focused on sources of NO<INF>X</INF> and SO<INF>2</INF> 
emissions in its control strategy analysis for the second planning 
period. Texas explained these are the main anthropogenic pollutants 
that affect visibility at Class I areas in Texas and Class I areas in 
neighboring states. Texas further stated that, ``on an individual 
basis, point sources are the largest contributors to SO<INF>2</INF> and 
NO<INF>X</INF>,'' and thus Texas elected to focus on point sources in 
this planning period.\71\
---------------------------------------------------------------------------

    \71\ 2021 Texas Regional Haze Plan at 7-3.
---------------------------------------------------------------------------

    Texas's source selection methodology relied on a two-step approach. 
As the first step for source selection, Texas developed areas of 
influence (AOIs) for thirteen \72\ Class I areas (in Texas and nearby 
states) to identify areas that may contain sources of NO<INF>X</INF> 
and SO<INF>2</INF> that were expected to contribute to visibility 
impairment at these areas. The AOIs are graphical representations of 
the extinction weighted residence time (EWRT), which combines air flow 
patterns with ammonium sulfate and ammonium nitrate extinction measured 
at IMPROVE monitors at the Class I areas on the 20% most impaired days. 
The TCEQ used the AOI of a Class I area as a brightline cutoff to 
define the boundaries within which to further evaluate sources located 
within that area. As the second step, Texas then applied a Q/d 
threshold for NO<INF>X</INF> and for SO<INF>2</INF> of greater than or 
equal to five to point sources located within the geographical area of 
the selected AOI threshold.\73\ As a result, any source within the AOI 
boundaries with a Q/d less than five or any source, regardless of its 
Q/d, that fell outside of the AOI boundaries were eliminated from 
further consideration.
---------------------------------------------------------------------------

    \72\ As discussed previously in section IV.C., the monitor for 
Guadalupe Mountains also serves as the monitor for Carlsbad Caverns 
in New Mexico.
    \73\ To calculate the Q/d for point sources, the TCEQ used 2028 
projected emissions (Q in tons per year) and distance from the Class 
I area monitor to the source (d in kilometers). For non-EGUs, Texas 
estimated 2028 future year emissions from 2016 reported emissions 
from the State of Texas Air Reporting System (STARS) coupled with 
growth factors developed by the consulting firm, Eastern Research 
Group, Inc. (ERG) See 2021 Texas Regional Haze Plan at 7-9. For 
EGUs, the TCEQ used data from the Eastern Regional Technical 
Advisory Committee (ERTAC) to estimate EGU projections for 2028. See 
2021 Texas Regional Haze Plan at 7-9.
---------------------------------------------------------------------------

    Although Texas determined AOIs for 13 Class I areas in Texas and 
nearby states, Texas's 2021 Regional Haze Plan focused only on those 
Class I areas where sources with a Q/d greater than or equal to five 
fell within the AOI boundary.\74\ Following this methodology, Texas 
selected 18 sources for further analysis for only four Class I areas: 
Wichita Mountains, Caney Creek, Guadalupe Mountains, and Salt 
Creek.\75\
---------------------------------------------------------------------------

    \74\ See 2021 Texas Regional Haze Plan, Figure 7-1 at 7-4 and 
Figure 7-2 at 7-5. Texas stated that those additional AOIs not 
represented in those figures in the SIP did not add additional 
sources for consideration. 2021 Texas Regional Haze Plan at 7-6.
    \75\ See Texas 2021 Regional Haze Plan at 7-5 to 7-6. Presented 
Class I areas are: Caney Creek, Guadalupe Mountains, Salt Creek, and 
Wichita Mountains for the NO<INF>X</INF> analysis, and Caney Creek, 
Guadalupe Mountains, and Wichita Mountains for the SO<INF>2</INF> 
analysis.

[[Page 83352]]



                     Table 7--Texas's Source Selection for Its 2021 Regional Haze Plan \76\
----------------------------------------------------------------------------------------------------------------
         Company/site name                    Unit(s)              Class I area(s)            Pollutant(s)
----------------------------------------------------------------------------------------------------------------
Coleto Creek Power/Coleto Creek     (1) coal boiler...........  Wichita Mountains....  SO2.
 Power Station.
Southwestern Electric Power/Welsh   (2) coal boilers..........  Caney Creek & Wichita  SO2.
 Power Plant.                                                    Mountains.
AEP/Pirkey Power Plant............  (1) coal boiler...........  Caney Creek & Wichita  SO2.
                                                                 Mountains.
NRG Energy/Limestone Electric       (2) coal boilers..........  Wichita Mountains....  SO2.
 Generating Station.
Vistra Energy/Martin Lake Electric  (3) coal boilers..........  Caney Creek & Wichita  SO2.
 Station.                                                        Mountains.
San Miguel Electric Cooperative/    (1) coal boiler...........  Guadalupe Mountains &  SO2.
 San Miguel Elec. Plant.                                         Wichita Mountains.
Public Service Co. of Oklahoma/     (1) coal boiler...........  Wichita Mountains....  SO2 & NOX.
 Oklaunion Power Station.
Vistra Energy/Oak Grove Steam       (2) coal boilers..........  Wichita Mountains....  SO2.
 Electric Station.
Holcim Texas LP/Midlothian Plant..  (2) cement kilns..........  Wichita Mountains....  SO2.
Vitro Flat Glass/Works No. 4        (2) glass melting furnaces  Wichita Mountains....  SO2 & NOX.
 Wichita Falls Plant.
Graphic Packaging International/    (4) boilers: (2) black      Caney Creek..........  NOX.
 Texarkana Mill.                     liquor solids & NG; (1)
                                     NG & fuel oil; (1) NG,
                                     fuel oil, & other
                                     materials.
El Paso Natural Gas Co./Keystone    (15) reciprocating engines  Guadalupe Mountains &  NOX.
 Compressor Station.                                             Salt Creek.
El Paso Natural Gas Co./Cornudas    (6) turbines..............  Guadalupe Mountains..  NOX.
 Plant.
El Paso Natural Gas Co./Guadalupe   (1) turbine...............  Guadalupe Mountains..  NOX.
 Compressor Station.
GCC Permian/Odessa Cement Plant...  (2) cement kilns..........  Guadalupe Mountains..  NOX.
Orion Engineered Carbons/Orange     (1) incinerator; (4)        Caney Creek..........  SO2.
 Carbon Black Plant.                 dryers; (2) tail gas and
                                     NG boilers; (1) flare.
Oxbow Calcining/Oxbow Calcining-    (4) coke calcining kilns..  Caney Creek..........  SO2.
 Port Arthur.
Trinity Lightweight Aggregate       (1) lightweight aggregate   Wichita Mountains....  SO2.
 (TRNLWS)/Streetman Plant.           kiln.
----------------------------------------------------------------------------------------------------------------

b. EPA's Evaluation of Texas's Source Selection Methodology
---------------------------------------------------------------------------

    \76\ Texas 2021 Regional Haze Plan, table 7-5.
---------------------------------------------------------------------------

    In identifying the required emission limits, schedules of 
compliance, and other measures as may be necessary to make reasonable 
progress toward meeting the national goal, States first select sources 
for consideration of the four statutory factors.\77\ Under the RHR, 
States have flexibility in conducting their source selection; however, 
Texas's source selection methodology was neither well-reasoned nor 
adequately justified.\78\ Notably, Texas did not select any sources for 
further analysis of control measures that may be necessary for 
inclusion as part of the long-term strategy to make reasonable progress 
for Big Bend National Park and did not select any SO<INF>2</INF> 
sources for consideration for Salt Creek. Moreover, the EPA finds the 
source selection methodology used by Texas was not adequately or 
accurately described. As such, the threshold Texas applied to define 
its AOIs was not justified. Without the proper justification, it is 
unclear how, despite these deficiencies, Texas makes reasonable 
progress at these Class I areas.
---------------------------------------------------------------------------

    \77\ See 40 CFR 51.308(f)(2); CAA 169A(g)(1).
    \78\ 2019 Guidance at 9, 13. The 2019 Guidance explains that in 
selecting sources, states must reasonably choose factors and apply 
them in a reasonable way given the statutory requirement to make 
reasonable progress towards national goal of preventing future and 
remedying existing anthropogenic visibility impairment). See CAA 
169A(b)(2). To that end, the 2019 Guidance recommends that states 
provide a detailed description of how the state used technical 
information to select a reasonable set of sources for an analysis of 
control measures including the basis for the visibility impact 
thresholds the state used (if applicable), and any other relevant 
information. See also 2021 Clarifications Memo at 3 (``States cannot 
reasonably determine that they are making reasonable progress if 
they have not adequately considered the contributors to visibility 
impairment. Thus, while states have discretion to reasonably select 
sources, this analysis should be designed and conducted to ensure 
that source selection results in a set of pollutants and sources the 
evaluation of which has the potential to meaningfully reduce their 
contributions to visibility impairment.'').
---------------------------------------------------------------------------

i. The TCEQ Failed To Adequately Describe the Criteria It Used To 
Select Sources
    Under 40 CFR 51.308(f)(2)(i), States are required to include a 
``description of the criteria it used to determine which sources or 
groups of sources it evaluated.'' Based on our review of the 2021 Texas 
Regional Haze Plan, the methodology Texas described in its SIP to 
develop its AOIs is inconsistent with, and would not result in, the 
AOIs presented in Texas's SIP. Texas states in its SIP that the AOIs 
were determined by dividing the EWRT for each cell by the sum total of 
all the EWRTs (i.e., EWRT for each cell) across the entire domain.\79\ 
However, based on the documentation the EPA obtained during early 
engagement in the Fall of 2020 and comparing it to what was in its 2021 
Regional Haze Plan, Texas actually divided the EWRT for each cell by 
the maximum EWRT in the domain for each respective pollutant. There was 
thus an inconsistency between what Texas said its methodology was, and 
what was in its 2021 Regional Haze Plan submission. Specifically, in 
the 2020 early engagement document, Texas stated, ``. . . prior to 
plotting the AOIs, the weighted probabilities were scaled to 1 by 
dividing the weighted probabilities in each cell by the maximum value 
in
---------------------------------------------------------------------------

    \79\ 2021 Texas Regional Haze Plan at 7-7.

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

[[Page 83353]]

a cell in the domain.'' \80\ The EPA compared the plotted AOIs Texas 
had submitted during the 2020 early engagement period with the plotted 
AOIs Texas submitted with its 2021 Regional Haze Plan. These AOIs are 
the same, confirming that, despite what Texas stated in its 2021 
Regional Haze Plan, Texas was actually following its articulated 
methodology in the 2020 early engagement document.
---------------------------------------------------------------------------

    \80\ See 
``README.AOIdevelopmentFor2021RHSIP_Response_to_EPArequest.20Nov2020u
pdate.docx'' available in the docket for this action.
---------------------------------------------------------------------------

    This early engagement information was not included in the proposed 
SIP Texas published during its state-level notice-and-comment process. 
Thus, Texas's SIP failed to accurately or adequately describe the 
criteria actually used in its 2021 Regional Haze Plan submission to 
determine which sources, or groups of sources, it chose to evaluate for 
additional control measures as required by 40 CFR 51.308(f)(2)(i). 
Without an accurate and adequate description of Texas's source 
selection methodology, it is not clear from its 2021 Texas Regional 
Haze Plan how Texas evaluated and determined the emission reduction 
measures that are necessary to make reasonable progress for its second 
planning period long-term strategy. We discuss the AOI methodologies 
and these inconsistencies further in the Technical Support Document 
(TSD) included in the docket for this action.
ii. Texas Failed To Adequately Justify Its AOI Threshold
    As noted in the previous section and more fully explained in the 
EPA's TSD, Texas selected sources using AOIs it developed for each 
Class I area then followed with a Q/d analysis. The AOIs established a 
brightline geographic boundary within which Texas selected sources with 
a Q/d of greater than or equal to five. In other words, Texas did not 
consider a source, regardless of the size of its emissions, if it was 
not first within the geographic area defined by the chosen AOI 
threshold.
    To define the brightline geographic boundaries of the AOIs, Texas 
applied a threshold of 0.1 or 10% of the maximum EWRT value for that 
AOI.\81\ Texas did not provide any discussion or justification for its 
selection of this threshold, nor did Texas explain how this threshold 
resulted in evaluating a meaningful set of sources for possible 
controls measures to improve visibility impairment. Further, Texas did 
not evaluate whether the selected threshold provided for AOIs that 
included a sufficiently large area to capture the sources with the 
highest emissions, or Q/d values, that impact visibility at certain 
Class I areas. The need for a justification is crucial when a State is 
applying the threshold as a brightline when selecting sources to 
evaluate for additional control measures, such as what Texas did here. 
The AOIs generated from EWRTs represent the general location that air 
parcels are coming from when visibility extinction is high. However, 
unless an appropriate threshold value is applied, they do not 
necessarily capture the specific sources of emissions that are 
contributing to visibility impairment at the Class I area.\82\ Texas's 
approach did not consider the size or location of point sources, 
despite articulating a specific focus on point sources,\83\ or the 
total emissions captured to support that their approach and chosen 
threshold resulted in a reasonable identification of sources for 
analysis in development of the long term strategy. This problem is 
evident in Texas's 2021 Regional Haze Plan, where several AOIs 
contained no sources identified for further consideration and several 
large emission sources with Q/d values far exceeding Texas's Q/d 
threshold of five being excluded from further consideration because 
they were located outside of Texas's generated AOIs.
---------------------------------------------------------------------------

    \81\ Texas discusses its AOI and Q/d analysis in section 7.2.1 
of its 2021 Texas Regional Haze Plan.
    \82\ The 2019 Guidance describes a source selection approach 
utilizing residence time analysis that selects sources for further 
analysis by giving each point source a score that takes into account 
the source's emissions, the daily values of light extinction at a 
Class I area, the distance between the source and a Class I area, 
and the relative frequency with which wind trajectories indicate 
that each source is upwind of the IMPROVE monitoring site. 2019 
Guidance at 13. This is the general approach followed by CenSARA and 
WRAP.
    \83\ Texas found that on an individual basis point sources are 
the largest contributors to visibility impairment in Class I areas. 
2021 Texas Regional Haze Plan at 7-3.
---------------------------------------------------------------------------

    For example, W A Parish is located just outside of Texas's ammonium 
sulfate AOIs for both Caney Creek and Wichita Mountains, and outside of 
Texas's ammonium sulfate AOI for Big Bend.\84\ The SO<INF>2</INF> Q/d 
values for W A Parish are 32.2 for Caney Creek, 28.2 for Wichita 
Mountains, and 25.1 for Big Bend.\85\ Tolk Generating Station is also 
located outside of Texas's ammonium sulfate AOI for Salt Creek; 
however, it has a Q/d value of over 84.\86\ Ammonium sulfate is the 
largest contributor to observed light extinction at Salt Creek \87\ but 
Texas did not identify any source of SO<INF>2</INF> emissions for 
further analysis due to the application of their AOI brightline test 
and selected EWRT threshold, despite the large SO<INF>2</INF> emissions 
from Tolk and the relative proximity of the facility to Salt Creek.\88\ 
Given the large emissions from these facilities, these sources likely 
are meaningfully contributing to visibility impairment, even if they 
happen to fall outside of the chosen Texas AOIs. Based on its analysis 
of other coal-fired EGUs with no controls or underperforming controls, 
had Texas selected these sources for further evaluation under the four 
factors, Texas may have found cost-effective controls available, 
resulting in emission reductions that may have been necessary for 
inclusion in its long-term strategy to make reasonable progress toward 
meeting the national goal. Moreover, Texas did not explain how not 
evaluating these high-emitting sources nonetheless results in a long-
term strategy that makes reasonable progress toward the national goal.
---------------------------------------------------------------------------

    \84\ See 2021 Texas Regional Haze Plan, Figure 7-2 at 7-5; AOI 
for Big Bend located in Texas's EWRT AMDA spreadsheet on TCEQ's AMDA 
website at https://www.tceq.texas.gov/assets/public/implementation/air/sip/haze/EWRT_AMDA_Pivot_final.xlsx. This spreadsheet is also 
available in our docket as ``Texas EWRT AMDA spreadsheet.xlsx''.
    \85\ See ``EPA Q_d Spreadsheet.xlsx'' available in the docket 
for this action. The information included in the EPA's spreadsheet 
used information available in our docket as ``Texas EWRT AMDA 
spreadsheet.xlsx''. See also Letter from Arkansas Department of 
Energy and Environment to TCEQ requesting that TCEQ consider, among 
other sources, whether performing a four-factor analysis is 
appropriate for the W A Parish facility in accordance with 40 CFR 
51.308(f)(2)(i) due to impacts on Caney Creek based on CenSARA's AOI 
study (Feb. 4, 2020). The letter is available in Appendix A of 
Texas's 2021 Regional Haze Plan at 84 of 227. See also Letter from 
Oklahoma Department of Environmental Quality to TCEQ requesting that 
TCEQ consider further evaluating the W A Parish facility based on 
its identification that the source is reasonably anticipated to 
contribute to visibility impairment at the Wichita Mountains 
Wilderness Area (July 17, 2020). The letter is available in Appendix 
A of Texas's 2021 Regional Haze Plan at 125 of 227.
    \86\ See AOI for Salt Creek located in ``Texas EWRT AMDA 
spreadsheet.xlsx'' available in the docket for this action. See 
``EPA Q_d Spreadsheet.xlsx'' available in the docket for this 
action. See also Letter from New Mexico Environment Department to 
TCEQ requesting among other things that Texas specifically evaluate 
the Tolk facility for additional controls based on its impact to 
Class I areas in New Mexico, including Salt Creek (Feb. 2, 2021). 
The letter is available in Appendix A of Texas's 2021 Regional Haze 
Plan at 111 of 227. See also, information provided by the FLMs 
during consultation that Tolk and W A Parish merit further 
evaluation based on emissions and potential emission reductions 
available. The information provided by the FLMs is available in 
Appendix A of Texas's 2021 Regional Haze Plan at 205 of 227.
    \87\ See 2021 Texas Regional Haze Plan, appendix F, Figure 1-60.
    \88\ EPA used information from Texas's EWRT AMDA spreadsheet, 
also available in our docket as ``Texas EWRT AMDA 
spreadsheet.xlsx''. We used the same information to calculate the 
SO<INF>2</INF> Q/d values for Tolk at White Mountain (56) and at 
Wheeler Peak (42.7).
---------------------------------------------------------------------------

    We therefore find Texas's unjustified use of its selected threshold 
and resulting AOIs as a brightline cutoff in

[[Page 83354]]

source selection to be unreasonable. Texas's methodology resulted in 
several of the highest emitting SO<INF>2</INF> stationary point sources 
in the State of Texas not being selected for further evaluation of 
controls to improve visibility impairment at the Class I areas they 
likely impact, and in the case of some Class I areas, no sources 
selected at all for further analysis using the four statutory factors 
for those areas.
iii. PSAT Modeling Results Further Demonstrate Unreasonableness of 
Texas's Source Selection Methodology
    The 2019 Guidance identifies photochemical modeling and the use of 
source apportionment modeling as possible methods to assess PM species 
impacts from sources or groups of sources for source selection.\89\ 
Texas conducted photochemical source apportionment modeling (known as 
the Particulate Matter Source Apportionment Technology, or PSAT, 
function of CAMx modeling) as part of its 2021 Regional Haze Plan to 
evaluate the impact of emissions from source categories on visibility 
in Class I areas.\90\ While Texas did not conduct PSAT modeling for the 
explicit purpose of source selection, Texas nevertheless included the 
results of the PSAT modeling in its SIP.\91\ The EPA finds Texas's own 
PSAT modeling results illustrate the flaws in Texas's source selection 
methodology.
---------------------------------------------------------------------------

    \89\ 2019 Guidance at 14-15.
    \90\ 2021 Texas Regional Haze Plan at 8-2.
    \91\ As explained in our 2019 Guidance, photochemical models are 
a more detailed and sophisticated technique for evaluating 
visibility impacts. Photochemical modeling considers the dispersion 
transformation and deposition processes. Source apportionment can 
``tag'' and track emissions sources by any combination of region and 
sector, or by individual source. As evidenced in Appendix A of 
Texas's 2021 Regional Haze Plan, Texas had the results of the PSAT 
modeling at least by March 31, 2020, when Texas presented the 
results to the FLMs during a consultation meeting.
---------------------------------------------------------------------------

    The TCEQ failed to address in its 2021 Regional Haze Plan how its 
source selection approach and resulting failure to select sources for 
further analysis to address visibility impairment at Big Bend are 
consistent with the CAA's statutory goal and Regional Haze Rule 
requirements.\92\ TCEQ's source selection methodology did not identify 
any sources for further analysis of control measures that may be 
necessary to include in its long-term strategy to make reasonable 
progress at Big Bend. The TCEQ's PSAT model results indicate that 
emissions from Texas anthropogenic sources account for over 10% of the 
total light extinction at Big Bend, and 67% of the light extinction due 
to U.S. anthropogenic emissions. \93\ The influence from Texas sources 
on light extinction at Big Bend is approximately double the influence 
from anthropogenic sources in the rest of the U.S. combined.\94\ While 
Texas states that visibility at Big Bend is heavily influenced by 
international emissions, the TCEQ has already accounted for this by 
adjusting the glidepath for its Class I areas to remove visibility 
impairment from international emissions, consistent with the EPA's 
guidance, and thus should not be used as a rationale for not evaluating 
sources for additional control measures. CAA 169A(a)(1), (b)(2) and the 
RHR require states to make reasonable progress towards addressing 
anthropogenic impairment from U.S. sources in the second planning 
period in furtherance of Congress's national goal.
---------------------------------------------------------------------------

    \92\ CAA 169A(a)(1), (b)(2); 40 CFR 51.308(f)(2).
    \93\ See 2021 Texas Regional Haze Plan Figure 8-21 at 8-46.
    \94\ See 2021 Texas Regional Haze Plan Figure 8-21 at 8-46.
---------------------------------------------------------------------------

    The influence of Texas sources on sulfate and nitrate 
concentrations at Big Bend shows that emissions from Texas sources are 
projected to account for approximately 65.4% of the particulate sulfate 
concentration and 59.3% of the nitrate concentration due to U.S. 
anthropogenic emissions.\95\ The vast majority (93.9%) \96\ of the 
Texas influence on particulate sulfate concentrations at Big Bend can 
be attributed to Texas anthropogenic emissions from electricity 
generating unit (EGU) point and non-EGU point sources.\97\ Therefore, 
these data demonstrate that Texas's AOI analysis and threshold 
selection for Big Bend did not adequately identify the relevant sources 
that impact visibility impairment for further analysis necessary to 
develop a long-term strategy to make reasonable progress at Big Bend.
---------------------------------------------------------------------------

    \95\ See 2021 Texas Regional Haze Plan, appendix F, Figure 1-52 
at F-54 and Figure 1-53 at F-55.
    \96\ See 2021 Texas Regional Haze Plan, appendix F, Figure 1-52 
at F-54.
    \97\ See 2021 Texas Regional Haze Plan, appendix F, Figure 1-52 
at F-54.
---------------------------------------------------------------------------

    Similarly, Texas's PSAT modeling also underscores inadequacies with 
its source selection for Class I areas in New Mexico, for example, Salt 
Creek. As noted above, Texas's AOI analysis for Salt Creek identified 
no sources of SO<INF>2</INF> in Texas for consideration for further 
analysis. However, the results of Texas's PSAT modeling show that Texas 
sources account for almost 12% of the light extinction at Salt 
Creek.\98\ The largest contributor to light extinction at Salt Creek is 
sulfate.\99\ Focusing on modeled U.S. anthropogenic impacts alone, 
Texas anthropogenic sources account for approximately 51.3% of the 
particulate sulfate concentrations at Salt Creek.\100\ Texas's chosen 
approach for source selection failed to identify any SO<INF>2</INF> 
point sources, despite accounting for over half of all the U.S. 
anthropogenic particulate sulfate concentrations at Salt Creek.
---------------------------------------------------------------------------

    \98\ See 2021 Texas Regional Haze Plan, appendix F at F-36.
    \99\ See 2021 Texas Regional Haze Plan, appendix F at F-62.
    \100\ See 2021 Texas Regional Haze Plan, appendix F at F-63.
---------------------------------------------------------------------------

    Class I areas like Salt Creek that are not projected to be on or 
under the glidepath are subject to additional requirements in the RHR. 
Under 40 CFR 51.308(f)(3)(ii)(B), Texas must provide a robust 
demonstration that there are no additional emission reduction measures 
for anthropogenic sources or groups of sources in the State that may 
reasonably be anticipated to contribute to visibility impairment in the 
Class I area that would be reasonable to include in its own long-term 
strategy.\101\ The influence from Texas's point sources on particulate 
sulfate concentrations at Salt Creek is more than double the amount of 
New Mexico's total (point source, non-point source, and mobile source) 
influence on particulate sulfate concentrations at Salt Creek.\102\ 
Meaning, SO<INF>2</INF> emissions from Texas sources contribute more to 
visibility impairment at Salt Creek than SO<INF>2</INF> emissions from 
New Mexico sources. Given the meaningful contribution to visibility 
impairment demonstrated by its PSAT modeling, Texas's decision not to 
select any SO<INF>2</INF> sources for further analysis and 
consideration of the four statutory factors (or to adequately justify 
the decision not to select these sources) fails to satisfy the 
requirement to provide for a robust demonstration for those Class I 
areas projected to be above the glidepath, as required by 40 CFR 
51.308(f)(3)(ii)(B).
---------------------------------------------------------------------------

    \101\ Texas's own modeling and the EPA's modeling demonstrated 
that Salt Creek would be above the adjusted glidepath.
    \102\ See 2021 Texas Regional Haze Plan, appendix F, Figure 1-61 
at F-63.
---------------------------------------------------------------------------

iv. EPA's Conclusions and Proposed Action on Source Selection
    The EPA finds the source selection methodology used by Texas was 
not adequately described as required by the RHR.\103\ Nevertheless, the 
EPA was able to discern the state's approach to

[[Page 83355]]

developing its AOIs which relied upon drawing a boundary based on a 
threshold of ten percent of the maximum EWRT values. Texas, however, 
did not provide any rationale or justification for this ten percent 
threshold. The boundaries of the AOIs were used as a brightline cutoff, 
with sources outside the AOIs not given any further consideration. As 
demonstrated in previous sections, Texas's methodology was unreasonable 
because it resulted in the selection of no sources for further 
evaluation at Big Bend and no SO<INF>2</INF> sources for further 
analysis at Salt Creek. Texas's own PSAT modeling results confirm that 
its methodology was unreasonable because the results show significant 
contribution from Texas anthropogenic sources to visibility impairment 
at Big Bend and Salt Creek. Texas made no attempt to explain the 
disconnect between its PSAT results and its source selection approach.
---------------------------------------------------------------------------

    \103\ 40 CFR 51.308(f)(2)(i) (``The State must evaluate and 
determine the emission reduction measures that are necessary to make 
reasonable progress . . . The State must include in its 
implementation plan a description of the criteria it used to 
determine which sources or groups of sources it evaluated'').
---------------------------------------------------------------------------

    The selection of a reasonable set of sources is a necessary first 
step in identifying the required emission limits, schedules of 
compliance, and other measures as may be necessary for inclusion in its 
long-term strategy to make reasonable progress toward meeting 
Congress's goal of preventing any future, and remedying any existing, 
impairment at Class I areas after consideration of the four statutory 
factors.\104\ It is evident that developing a long term strategy to 
make reasonable progress cannot be met, if no sources of pollutants 
shown to be meaningful contributors to impairment are selected for 
further evaluation. It is further evident that, at least for Big Bend 
for both NO<INF>X</INF> and SO<INF>2</INF> and for Salt Creek for 
SO<INF>2</INF>, Texas's method of establishing an AOI is not adequate 
to identify sources of visibility impairment in Texas.
---------------------------------------------------------------------------

    \104\ See 40 CFR 51.308(f)(2).
---------------------------------------------------------------------------

    Therefore, the EPA is proposing to disapprove the portion of 
Texas's 2021 Regional Haze Plan addressing the regulatory requirements 
of the long-term strategy under 40 CFR 51.308(f)(2).
2. Four Factor Analysis
    This section discusses the technical bases and information Texas 
relied on in the evaluation of emission reduction measures necessary to 
make reasonable progress in each Class I area affected by emissions 
from Texas when developing its long-term strategy for the second 
planning period. As discussed in the preceding section, Texas selected 
18 sources for evaluation of emissions reductions necessary to make 
reasonable progress.\105\ If a source triggered analysis for both 
NO<INF>X</INF> and SO<INF>2</INF>, control strategies for both 
pollutants were analyzed separately and concurrently.\106\ Of the 18 
sources selected for evaluation, eight are EGU sources and 10 are non-
EGU sources.
---------------------------------------------------------------------------

    \105\ 2021 Texas Regional Haze Plan table 7-5 at 7-15.
    \106\ 2021 Texas Regional Haze Plan at 7-11.
---------------------------------------------------------------------------

    Based on the statutory and regulatory requirements, Texas evaluated 
emission reduction measures that are necessary to make reasonable 
progress by considering the four statutory factors listed in CAA Sec.  
169A(g)(1) and 40 CFR 51.308(f)(2)(i) for these selected sources. The 
four statutory factors are (1) the cost 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. This is commonly referred to as 
``the four-factor analysis.'' The four statutory factors must be 
considered when evaluating and determining the emissions reductions 
measures that are necessary to make reasonable progress.\107\ Although 
visibility impact is not one of the factors required for consideration 
under the CAA and the RHR, Texas opted to evaluate and consider the 
visibility benefits from selected control measures evaluated in the 
four-factor analysis by conducting photochemical sensitivity 
modeling.\108\ In the subsections that follow, we discuss Texas's 
analysis of the four statutory factors.
---------------------------------------------------------------------------

    \107\ 40 CFR 51.308(f)(2)(i).
    \108\ 2021 Texas Regional Haze Plan at 7-11.
---------------------------------------------------------------------------

a. Identification of Potential Controls
    In accordance with EPA's 2019 Guidance, ``the first step in 
characterizing control measures for a source is the identification of 
technically feasible control measures for those pollutants that 
contribute to visibility impairment.'' \109\ The EPA's 2019 Guidance 
does not define the term ``technically feasible;'' however, EPA's 
Regional Haze Regulations and Guidelines for Best Available Retrofit 
Technology (BART) Determinations (the BART Guidelines) states:
---------------------------------------------------------------------------

    \109\ 2019 Guidance at 22.

    Control technologies are technically feasible if either (1) they 
have been installed and operated successfully for the type of source 
under review under similar conditions, or (2) the technology could 
be applied to the source under review. Two key concepts are 
important in determining whether a technology could be applied: 
``availability'' and ``applicability.'' . . . a technology is 
considered ``available'' if the source owner may obtain it through 
commercial channels, or it is otherwise available within the common 
sense meaning of the term. An available technology is ``applicable'' 
if it can reasonably be installed and operated on the source type 
under consideration. A technology that is available and applicable 
is technically feasible.\110\
---------------------------------------------------------------------------

    \110\ 40 CFR part 51, appendix Y, Section D, Step 2.

    A reasonable four-factor analysis will consider the full range of 
potentially reasonable options for reducing emissions.\111\ In order to 
provide guidance on what control measures should be included in their 
four-factor analysis, the RHR Guidance lists examples of different 
types of control measures that states may consider.\112\
---------------------------------------------------------------------------

    \111\ 2019 Guidance at 22.
    \112\ 2019 Guidance at 29-30.
---------------------------------------------------------------------------

    For EGUs without existing controls, Texas considered and evaluated 
dry sorbent injection (DSI), spray dryer absorber (SDA), and wet 
limestone scrubbing systems (wet FGD) as potential SO<INF>2</INF> 
control options, and selective catalytic reduction (SCR) and selective 
non-catalytic reduction (SNCR) as potential NOx controls.\113\ For EGUs 
with existing SO<INF>2</INF> controls, Texas considered and evaluated 
upgrading the control efficiency of the controls to 95%.\114\ For non-
EGUs, Texas considered various NO<INF>X</INF> and SO<INF>2</INF> 
control options depending on the type of source and whether it had 
existing controls.\115\
---------------------------------------------------------------------------

    \113\ 2021 Texas Regional Haze Plan, appendix B at B-1.
    \114\ 2021 Texas Regional Haze Plan, appendix B at B-1 and B-5 
to B-6.
    \115\ 2021 Texas Regional Haze Plan, appendix B at B-1.
---------------------------------------------------------------------------

    For selected sources where Texas could not identify any feasible 
control options for a particular source-type, that particular source 
and pollutant was not further evaluated in the four-factor analysis. 
Texas stated that it only considered control technologies that have 
been demonstrated as technically feasible for units at each source type 
and evaluated those control technologies using available unit-specific 
data. Texas deemed a given control technology to be ``demonstrated to 
be technically feasible'' if it was identified in the EPA's Reasonably 
Available Control Technology/Best Available Control Technology/Lowest 
Achievable Emission Rate (RACT/BACT/LAER) Clearinghouse or operated in 
industrial applications for units within an industry type not in a 
performance ``trial'' phase.\116\ Texas further explained that a 
control measure or technique that has been established as technically 
demonstrated or feasible

[[Page 83356]]

in one industry type was not considered to extend automatically to 
other industry types. Based on Texas's approach, Texas determined that 
there were no technically feasible controls for three of the 18 sources 
selected for further evaluation using the four factors: the Orion 
Carbon Black facility in Orange County, the Oxbow Calcining facility in 
Jefferson County, and the Streetman facility in Navarro County. These 
three determinations are discussed in more detail in the following 
paragraphs.
---------------------------------------------------------------------------

    \116\ 2021 Texas Regional Haze Plan, appendix B at B-3.
---------------------------------------------------------------------------

    Initially we note that Texas's search for available controls relied 
primarily on the RACT/BACT/LAER Clearinghouse. BACT and LAER are terms 
associated with EPA's ``New Source Review'' (NSR) permitting program 
and is triggered when a company is planning to build a new plant or 
modify an existing plant such that air pollution emissions will 
increase by a large amount. EPA established the RACT/BACT/LAER 
Clearinghouse to provide a central data base of air pollution 
technology information (including past RACT, BACT, and LAER decisions 
contained in NSR permits) to promote the sharing of information among 
permitting agencies and to aid in future case-by-case 
determinations.\117\ We note that many of the petroleum coke calcining 
plants and carbon black plants were constructed prior to the start of 
EPA's NSR permitting program and have generally not been modified in 
ways that would trigger the permitting programs.\118\ As a result, 
Texas's reliance on that RACT/BACT/LAER Clearinghouse is not a 
sufficient search for these types of facilities.
---------------------------------------------------------------------------

    \117\ See RACT/BACT/LAER Clearinghouse (RBLC) Basic Information 
available at https://www.epa.gov/catc/ractbactlaer-clearinghouse-rblc-basic-information.
    \118\ See, e.g., Port Arthur Steam Energy/Oxbow Corp., available 
at https://chptap.ornl.gov/profile/186/Port_Arthur_Steam-Project_Profile.pdf.
---------------------------------------------------------------------------

    In fact, several groups commented during Texas's state-level 
comment period that there were technically feasible controls available 
for petroleum coke calcining facilities similar to the Oxbow facility. 
For example, commenters referenced a report which includes a discussion 
of a petroleum coke calcining plant that currently operates a DSI 
system to control emissions.\119\ Additionally, the report identifies a 
Tesoro facility that operates a semi-dry scrubber combined with a wet 
electrostatic precipitator that reduces SO<INF>2</INF> emissions in 
excess of 95%.\120\ In response to these comments, Texas stated that:
---------------------------------------------------------------------------

    \119\ Bay Area Air Quality Management District Regulation 9, 
Rule 14 Report at 4, 9 (Oct. 2015).
    \120\ Bay Area Air Quality Management District Regulation 9, 
Rule 14 Report at 11 (Oct. 2015).

    The control technology the commenter provided may be technically 
feasible for petroleum coke calcining manufacturing sites but would 
not necessarily be considered technically demonstrated directly on 
the kilns such that this technology could be implemented at Oxbow's 
Port Arthur facility as suggested by the commenter. The possible 
control options suggested by the commenter would require 
modification to a site's operational process such that a potential 
SO<INF>2</INF> post-combustion control strategy could technically be 
implemented to control SO<INF>2</INF> emissions from petroleum coke 
calcining kilns. The TCEQ notes these potential strategies would be 
implemented downstream of the kiln, or kilns, and not directly on 
the kiln. The operational process modification would require 
additional process units to the site to make the potential post-
combustion SO<INF>2</INF> control measure technically feasible, 
thereby increasing capital expenditures not directly associated with 
the new, additional control measure but necessary for the control 
measure to effectively function and control SO<INF>2</INF> emissions 
from the petroleum coke calcining kiln. The TCEQ contends these 
higher-level control analysis approaches require much broader and 
resource intensive engineering and economic analyses, and they may 
not result in the potential control strategy being deemed cost-
effective or reasonable and necessary for making reasonable progress 
for long-term strategies for a planning period.\121\
---------------------------------------------------------------------------

    \121\ 2021 Texas Regional Haze Plan, Response to Comments, at 
481-482 of 653.

    While Texas's response indicates that such control technologies may 
not be cost effective based on the modifications that may need to occur 
at the site, such a determination would necessarily come out of a four-
factor analysis; it does not explain why Texas's SIP continued to find 
that such control measures were not technically feasible.\122\ In fact, 
it acknowledges that such control technologies may be technically 
feasible. To the extent Texas is relying on the fact that the costs of 
this control technology would be prohibitive, Texas needed to provide a 
cost analysis to document and support such an assumption.\123\
---------------------------------------------------------------------------

    \122\ See EPA's TSD for this action, available in the docket, 
for additional information regarding the installation and operation 
of controls on petroleum coke calcining plants.
    \123\ 40 CFR 51.308(f)(2)(iii).
---------------------------------------------------------------------------

    Furthermore, information provided by Oxbow during Texas's comment 
period acknowledge that while there is limited publicly available 
information there are ``a few commercially operating post-combustion 
SO<INF>2</INF> controls systems installed on petroleum coke kilns.'' 
\124\ Oxbow also provided a four-factor analysis conducted by Sargent & 
Lundy.\125\ Specifically, Sargent & Lundy concluded that, based on 
engineering judgment and information from control system vendors, 
several control technologies were technically feasible and commercially 
available including: a DSI system with a fabric filter; \126\ a spray 
dryer flue gas scrubber system; \127\ a wet limestone scrubbing system; 
\128\ and a circulating dry scrubber system.\129\ Despite information 
provided to Texas to the contrary, the State continued to find that 
control technologies were not technically feasible. Therefore, Texas's 
determination that such control technologies were not technically 
feasible for petroleum coke calcining facilities was not reasonable. As 
a result, because Texas selected this source for further evaluation of 
control measures, it was unreasonable for Texas to not take into 
consideration the four statutory factors to determine whether there 
were cost-effective measures that were thus necessary for reasonable 
progress in fulfillment of their long-term strategy requirements for 
the second planning period.\130\
---------------------------------------------------------------------------

    \124\ Oxbow Comments on 2021 Texas Regional Haze Plan, at 306 of 
653. According to a 2022 technical support document (TSD) prepared 
by EPA, there are only approximately 15 petroleum coke calcining 
facilities operating in the United States. The EPA 2022 TSD is 
available in the docket for this action.
    \125\ Oxbow Comments on 2021 Texas Regional Haze Plan, Report 
from Sargent & Lundy at 312 of 653.
    \126\ Oxbow Comments on 2021 Texas Regional Haze Plan, Report 
from Sargent & Lundy at 338 of 653.
    \127\ Oxbow Comments on 2021 Texas Regional Haze Plan, Report 
from Sargent & Lundy at 336 of 653.
    \128\ Oxbow Comments on 2021 Texas Regional Haze Plan, Report 
from Sargent & Lundy at 334 of 653.
    \129\ Oxbow Comments on 2021 Texas Regional Haze Plan, Report 
from Sargent & Lundy at 336 of 653.
    \130\ We discuss additional examples of existing controls at 
coke calcining facilities in the TSD for this action, included in 
the docket.
---------------------------------------------------------------------------

    Texas received similar comments regarding Texas's determination 
that there were no feasible controls for the Orion carbon black plant. 
Notably, the commenter states that the EPA had entered into consent 
decrees with several carbon black manufacturing companies that required 
control of SO<INF>2</INF> emissions to 95%.\131\ In response to these 
comments, Texas stated that while these consent decrees required 
certain control efficiencies, installing controls on carbon black 
facilities had yet to be demonstrated in practice. However, the EPA 
entered into a consent decree with

[[Page 83357]]

the carbon black manufacturing company Cabot, which required the 
installation of wet gas scrubbers to control SO<INF>2</INF> emissions 
from their carbon black units. While the compliance dates were 
delayed,\132\ Cabot completed construction of the wet gas scrubber at 
its Canal Plant in 2020.\133\ Thus, the available information 
identifies technically feasible and available control technologies for 
carbon black facilities. Therefore, Texas's determination that no 
control technologies were technically feasible was unreasonable. Texas 
should have conducted a four-factor analysis for the Orion carbon black 
plant considering these available controls to determine whether cost-
effective control measures were necessary for reasonable progress in 
fulfillment of its long-term strategy requirements.
---------------------------------------------------------------------------

    \131\ See 2021 Texas Regional Haze SIP, Comments by Sierra Club, 
et al., on Texas's Regional Haze SIP at 253 of 653.
    \132\ See, United States of America, et al. v. Cabot 
Corporation, Civil Action Number 6:13-cv-03095 (W.D. LA), Second 
Amendment to Consent Decree (filed Dec. 22, 2017) and available in 
the docket for this action.
    \133\ See Cabot press release dated June 26, 2020, regarding the 
successful installation of control technologies, available at 
https://investor.cabot-corp.com/node/21156.
---------------------------------------------------------------------------

    Texas also received comments during Texas's state-level public 
comment period that there were technically feasible controls identified 
for lightweight aggregate plants like Streetman's plant.\134\ 
Specifically, commenters referenced EPA's AP-42 emission factor 
documentation \135\ for lightweight aggregate manufacturing. Among 
other information, the document identifies that emissions from kilns at 
these lightweight aggregate facilities are controlled with wet 
scrubbers as well as fabric filters and electrostatic precipitators 
(ESPs). In response to this information, Texas stated that review of 
the data and information in the EPA's AP-42 emission factor dataset led 
the TCEQ to conclude that ``while wet scrubbers designed for PM control 
may result in some emissions reductions of SO<INF>2</INF>, the TCEQ 
does not view this as a control strategy for the direct control of 
SO<INF>2</INF> that could result in meaningful SO<INF>2</INF> emissions 
reductions.'' \136\
---------------------------------------------------------------------------

    \134\ See 2021 Texas Regional Haze Plan, Comments by Sierra 
Club, et al. on Texas's Regional Haze SIP at 252 of 653.
    \135\ AP-42 emission factors are published by EPA and serve as 
the primarily compilation of emission factor information. The 
various chapters contain emissions factors and process information 
for more than 200 air pollution source categories. A source category 
is a specific industry sector or group of similar emitting sources. 
The emissions factors have been developed and compiled from source 
test data, material balance studies, and engineering estimates. See 
AP-42: Compilation of Air Emissions Factors from Stationary Sources 
available at https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors-stationary-sources for more information.
    \136\ 2021 Texas Regional Haze Plan, Response to Comments at 
482-483 of 653.
---------------------------------------------------------------------------

    While the EPA's AP-42 emission factor documentation discusses the 
use of scrubbers to control PM emissions, it also provides information 
and emission factors related to the control of SO<INF>2</INF> emissions 
from the installation of wet scrubbers.\137\ Several of the studies 
referenced in the documentation were done to measure SO<INF>2</INF> 
emissions.\138\ This information together shows reductions in emissions 
of SO<INF>2</INF> from the installation of wet scrubbers at lightweight 
aggregate plants.\139\ Regardless of whether the main pollutant of 
concern from these types of facilities is PM or SO<INF>2</INF>, Texas 
does not adequately or reasonably explain how a proven control 
technology, installed within the same industry type and for which 
reduces the pollutant of concern (SO<INF>2</INF>), becomes technically 
infeasible based on the fact that it also reduces PM. Texas's 
determination that there were no technically available controls for 
lightweight aggregate plants such as the Streetman facility was 
unreasonable and unsupported by information provided to Texas during 
its public comment period.\140\ Therefore, it was unreasonable for 
Texas not to have evaluated potential control measures for the 
Streetman facility using the four statutory factors to determine 
whether control measures were necessary for reasonable progress in 
fulfillment of their long-term strategy requirements.
---------------------------------------------------------------------------

    \137\ AP-42, section 11.20 available at https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-fifth-edition-volume-i-chapter-11-mineral-products-0 and in the docket for this action.
    \138\ See AP-42, section 11.20 See also AP-42 section 11.20 at 
pgs. 5, 10-12.
    \139\ See AP-42, section 11.20, table 4-13, Emission factors for 
rotary kilns without a scrubber are 5.6 lbs SO<INF>2</INF>/ton feed, 
with a scrubber 3.4 lbs SO<INF>2</INF>/ton feed.
    \140\ See 2021 Texas Regional Haze Plan, Comments by Sierra 
Club, et al, on Texas's Regional Haze SIP at 252 of 653. See also 
2021 Texas Regional Haze Plan, appendix A at 206 of 227.
---------------------------------------------------------------------------

b. Cost of Compliance
    Texas evaluated the cost of compliance for each control option 
determined to be technically feasible for each selected EGU and non-EGU 
to arrive at an annualized cost and cost per ton of emissions reduced 
($/ton), also referred to as a cost-effectiveness calculation, for each 
control option.\141\ Texas stated that as part of the cost analysis, 
individual units at a source selected for evaluation with 
NO<INF>X</INF> or SO<INF>2</INF> emissions of less than five percent of 
the facility's total emissions of the same pollutant were eliminated 
from further analysis.\142\ Texas explained that excluding such units 
with smaller emissions is reasonable with respect to application of the 
cost of compliance criterion because controlling these smaller units 
would not be justified at this time considering both the cost to 
control and the anticipated improvement in visibility. Using this 
approach, Texas focused on the units with relatively greater 
NO<INF>X</INF> and SO<INF>2</INF> emissions at a given source.
---------------------------------------------------------------------------

    \141\ 2021 Texas Regional Haze Plan, appendix B.
    \142\ 2021 Texas Regional Haze Plan, appendix B at B-3.
---------------------------------------------------------------------------

    In the cost analysis for EGUs without existing controls, Texas 
stated it estimated the capital cost and annual operating and 
maintenance costs of technically feasible air pollution control options 
using the most recent data available from Sargent & Lundy.\143\ In the 
cost analysis for upgrading scrubbers at EGUs, Texas provided an 
example cost, but did not explain how that example was used.\144\ In 
the cost analysis for non-EGUs, Texas stated it estimated the capital 
cost and annual operating and maintenance costs of technically feasible 
air pollution control options using cost data and information from the 
EPA and available industry literature.\145\ For one non-EGU source, the 
Works No. 4 Glass Plant, Texas relied on vendor cost information for 
capital cost and annual operating and maintenance costs of control 
equipment.\146\ For all sources, Texas estimated annualized capital 
costs by multiplying the capital costs by the capital recovery 
factor.\147\ The capital recovery factor accounts for source financing 
of air pollution control equipment and is based on the assumed 
equipment life and interest rate. Texas stated that ``capital recovery 
factors were estimated using the techniques listed in the EPA's Control 
Cost Manual'' where it found appropriate.\148\ Texas estimated the 
capital recovery factor assuming an interest rate of 10 percent and an 
equipment life of five, 15, and 30 years. Ultimately, Texas chose to 
base its cost analysis on a

[[Page 83358]]

capital life of 15 years for all selected sources.\149\
---------------------------------------------------------------------------

    \143\ 2021 Texas Regional Haze Plan at 7-11 to 7-12.
    \144\ 2021 Texas Regional Haze Plan, appendix B at B-12.
    \145\ 2021 Texas Regional Haze Plan, appendix B at B-12.
    \146\ 2021 Texas Regional Haze Plan, appendix B at B-7 to B-8, 
B-12.
    \147\ 2021 Texas Regional Haze Plan, appendix B at B-14.
    \148\ 2021 Texas Regional Haze Plan, appendix B at B-14.
    \149\ 2021 Texas Regional Haze Plan, appendix B at B-14.
---------------------------------------------------------------------------

    Texas stated that annual operating and maintenance costs associated 
with each control option evaluated ``were estimated from the same data 
and information used for estimating capital costs for each source.'' 
\150\ Texas added the annualized capital cost and the annual operating 
and maintenance cost to arrive at the total annualized cost for each 
control option for each source.\151\ After estimating the potential 
emission reductions of each control option using baseline emissions 
from the EPA's 2018 Clean Air Markets Program Data (AMPD) emission data 
for EGUs and 2016 TCEQ point source emission inventory data for non-
EGUs, the total annualized cost was divided by the tons of pollutant 
emissions reduced to estimate the cost per ton of emissions reduced ($/
ton), or cost-effectiveness.\152\ Texas then applied a cost-
effectiveness ($/ton) threshold of $5,000/ton for NO<INF>X</INF> and 
SO<INF>2</INF> emissions reduced to eliminate controls from further 
consideration by explaining that this allowed for the identification of 
sources to which potential control measures could be applied cost-
effectively.\153\ The results of Texas's cost analysis are presented in 
the following tables.\154\
---------------------------------------------------------------------------

    \150\ 2021 Texas Regional Haze Plan, appendix B at B-14.
    \151\ 2021 Texas Regional Haze Plan, appendix B at B-14.
    \152\ 2021 Texas Regional Haze Plan, appendix B at B-14.
    \153\ 2021 Texas Regional Haze Plan, appendix B at B-15.
    \154\ The information contained in tables 8 through table 17 are 
presented in the 2021 Texas Regional Haze Plan, appendix B at B-16-
B-42.

                                   Table 8--Texas's Cost Estimates of SO2 Controls for EGUs Without Existing Controls
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          SO2                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        SO2           cost-            cost-            cost-
               Source                  emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Coleto Creek Unit 1.................       13,213  DSI.....................           90       11,892           $3,261           $3,022           $2,976
                                                   SDA.....................           95       12,552            6,720            3,884            3,340
                                                   Wet FGD.................           98       12,949            7,406            4,215            3,603
Welsh Unit 1........................        7,528  DSI.....................           90        6,775            4,406            4,029            3,957
                                                   SDA.....................           95        7,152           11,380            6,481            5,540
                                                   Wet FGD.................           98        7,377           12,032            6,812            5,811
Welsh Unit 3........................        6,694  DSI.....................           90        6,025            4,814            4,394            4,314
                                                   SDA.....................           95        6,359           12,622            7,179            6,135
                                                   Wet FGD.................           98        6,560           13,357            7,558            6,445
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                          Table 9--Texas's Cost Estimates of SO2 Wet Scrubber Upgrades for EGUs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            SO2 reduction    Cost-effectiveness ($/ton)
                                                             SO2 baseline                     Annual       due to scrubber -----------------------------
                                                  Unit size    emissions   Capital cost   operating and    upgrade at 95%
                     Source                         (MW)       (tons/yr)        ($)        maintenance         control       5-Year    15-Year   30-Year
                                                                                            costs ($)     efficiency (tons/   life      life      life
                                                                                                                 yr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEP Pirkey Unit 1..............................         721         5,085    99,921,030        2,740,188             3,874    $7,511    $4,098    $3,443
Limestone Unit 1...............................         893         4,156   123,757,947        3,393,881             3,212    11,222     6,123     5,145
Limestone Unit 2...............................         957         4,164   132,627,498        3,637,115             3,259    11,853     6,467     5,434
Martin Lake Unit 1.............................         793        19,282   109,899,275        3,013,827            16,172     1,979     1,080       907
Martin Lake Unit 2.............................         793        17,167   109,899,275        3,013,827            14,101     2,270     1,238     1,040
Martin Lake Unit 3.............................         793        19,749   109,899,275        3,013,827            16,458     1,945     1,061       891
San Miguel Unit 1..............................         410        12,006    56,820,558        1,558,221             2,001     8,270     4,512     3,791
Oklaunion Unit 1...............................         720         2,191    99,782,444        2,736,387             1,826    15,913     8,682     7,295
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                            Table 10-Texas's Cost Estimates of NOX Controls Oklaunion Unit 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
               Source                  emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Oklaunion Unit 1....................        6,804  SNCR....................           50        3,402           $4,705           $4,152           $4,046
                                                   SCR.....................           98        6,668           11,222            6,455            5,541
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                    Table 11--Texas's Cost Estimate of SO2 Wet Scrubber Upgrades for Midlothian Plant
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Baseline SO2                                   SO2 reduction    Cost-effectiveness ($/ton)
                                                     SO2        control                       Annual       due to scrubber -----------------------------
                                                  baseline    efficiency   Capital cost   operating and    upgrade at 95%
                      Unit                        emissions     of wet          ($)        maintenance         control       5-Year    15-Year   30-Year
                                                  (tons/yr)  scrubber (%)                   costs ($)     efficiency (tons/   life      life      life
                                                                                                                 yr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cement Kiln No 1...............................         522            90     8,196,683          224,782               261    $9,138    $4,986    $4,189
Cement Kiln No 2...............................         856            90     8,300,438          227,627               428     5,647     3,081     2,589
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 83359]]


                              Table 12--Texas's Cost Estimate of Tri-Mer Cat Controls for Vitro Flat Glass Works No 4 Plant
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Control                   5-Year life      15-Year life     30-Year life
                                                                 Baseline    efficiency    Emissions        cost-            cost-            cost-
               Unit                    Pollutant evaluated      emissions     evaluated    reduction    effectiveness    effectiveness    effectiveness
                                                                (tons/yr)        (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Glass Melting Furnace Line No.1...  SO2......................          136            80          109          $15,100          $10,300           $9,400
                                    NOX......................          674            80          539           15,100           10,300            9,400
Glass Melting Furnace Line No. 2..  SO2......................          301            80          241            4,600            3,200            2,900
                                    NOX......................        2,533            80        2,026            4,600            3,200            2,900
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                  Table 13--Texas's Cost Estimates of NOX Controls for Graphic Packaging Texarkana Mill
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
                Unit                   emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Power Boiler No 1...................          109  LNB.....................           40           44          $21,788          $10,859           $8,762
                                                   SCR.....................           80           87           36,200           26,350           24,469
Power Boiler No 2...................          692  LNB.....................           40          277            3,525            1,757            1,417
                                                   SCR.....................           80          554            7,100            5,254            4,956
Recovery Boiler/Furnace No 1........          275  LNB.....................           40          110            7,438            3,707            2,991
                                                   SCR.....................           80          220           11,800            9,248            8,755
Recovery Boiler/Furnace No 2........          674  LNB.....................           40          270            3,619            1,804            1,455
                                                   SCR.....................           80          539            7,000            5,395            5,089
--------------------------------------------------------------------------------------------------------------------------------------------------------


                      Table 14--Texas's Cost Estimates of NOX Controls for El Paso Natural Gas Company Keystone Compressor Station
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
                Unit                   emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Reciprocating Internal Combustion             131  LEC.....................           40           53           $1,091             $544             $439
 Engine, A01.                                      SCR.....................           80          105            7,956            6,754            6,523
Reciprocating Internal Combustion               7  LEC.....................           40            3           19,209            9,573            7,724
 Engine, A02.                                      SCR.....................           80            6          129,200          108,036          103,974
Reciprocating Internal Combustion             133  LEC.....................           40           53            1,078              537              433
 Engine, A03.                                      SCR.....................           80          106            7,900            6,677            6,449
Reciprocating Internal Combustion              14  LEC.....................           40            6            9,989            4,978            4,017
 Engine, A04.                                      SCR.....................           80           11           67,500           56,494           54,381
Reciprocating Internal Combustion              24  LEC.....................           40           10            5,964            2,972            2,398
 Engine, A05.                                      SCR.....................           80           19           40,600           33,990           32,729
Reciprocating Internal Combustion              17  LEC.....................           40            7            8,664            4,318            3,484
 Engine, A06.                                      SCR.....................           80           13           58,600           49,085           47,253
Reciprocating Internal Combustion              14  LEC.....................           40            6           10,278            5,122            4,133
 Engine, A07.                                      SCR.....................           80           11           69,400           58,102           55,928
Reciprocating Internal Combustion              18  LEC.....................           40           12            4,851            2,418            1,915
 Engine, A08.                                      SCR.....................           80           24           33,100           27,769           26,743
Reciprocating Internal Combustion              16  LEC.....................           40            6            9,154            4,562            3,681
 Engine, A09.                                      SCR.....................           80           13           61,900           51,821           49,885
Reciprocating Internal Combustion              60  LEC.....................           40           24            2,377            1,185              956
 Engine, A10.                                      SCR.....................           80           48           16,600           13,940           13,437
Reciprocating Internal Combustion              34  LEC.....................           40           14            4,178            2,083            1,680
 Engine, A11.                                      SCR.....................           80           27           28,600           24,011           23,127
Reciprocating Internal Combustion               8  LEC.....................           40            3           18,554            9,247            7,461
 Engine, A12.                                      SCR.....................           80            6          124,800          104,367          100,443
Reciprocating Internal Combustion              29  LEC.....................           40           12            6,727            3,353            2,705
 Engine, B01.                                      SCR.....................           80           23           39,100           32,227           30,914
Reciprocating Internal Combustion              83  LEC.....................           40           33            2,365            1,179              951
 Engine, B02.                                      SCR.....................           80           66           14,200           11,755           11,293
Reciprocating Internal Combustion              66  LEC.....................           40           26            2,958            1,474            1,189
 Engine, B03.                                      SCR.....................           80           53           17,600           14,543           13,965
--------------------------------------------------------------------------------------------------------------------------------------------------------


                             Table 15--Texas's Cost Estimates of NOX Controls for El Paso Natural Gas Company Cornudas Plant
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
                Unit                   emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gas Turbine, A1.....................           69  LNB.....................           40           28           $1,913             $954             $769
                                                   SCR.....................           80           55           27,700           21,972           20,879
Gas Turbine, A2.....................           50  LNB.....................           40           20            5,823            2,902            2,341
                                                   SCR.....................           80           40           37,742           29,958           28,464
Gas Turbine, A3.....................           63  LNB.....................           40           25            4,623            2,304            1,859
                                                   SCR.....................           80           51           30,292           24,112           22,926
Gas Turbine, B1.....................          104  LNB.....................           40           42            3,748            1,868            1,507
                                                   SCR.....................           80           83           22,878           17,982           17,042
Gas Turbine, C1.....................           18  SCR.....................           80           14          129,955          101,694           96,270

[[Page 83360]]

 
Gas Turbine, C2.....................           18  SCR.....................           80           14          129,955          101,694           96,270
--------------------------------------------------------------------------------------------------------------------------------------------------------


                      Table 16--Texas's Cost Estimates of NOX Controls for El Paso Natural Gas Company Guadalupe Compressor Station
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
                Unit                   emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gas Turbine, C-1....................           56  LNB.....................           40           23          $13,897           $6,926           $5,588
                                                   SCR.....................           80           45           69,485           54,975           52,190
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                  Table 17--Texas's Cost Estimates of NOX Controls for GCC Permian Odessa Cement Plant
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          NOX                                                            5-Year life      15-Year life     30-Year life
                                        baseline                               Control        NOX           cost-            cost-            cost-
                Unit                   emissions            Control           efficiency   reduction    effectiveness    effectiveness    effectiveness
                                       (tons/yr)                                 (%)       (tons/yr)       ($/ton)          ($/ton)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cement Kiln No 2....................          427  LNB.....................           40          171           $3,163           $1,576           $1,272
--------------------------------------------------------------------------------------------------------------------------------------------------------

i. Texas Did Not Adequately Document the Technical Basis and Cost 
Information on Which It Based Its Cost of Compliance Analyses as 
Required by the Regional Haze Rule
    Texas did not adequately document the technical basis and cost 
information on which it based its evaluation of the cost of compliance 
for all control measures considered as required by the Regional Haze 
Rule.\155\ The SIP submittal discusses Texas's general approach for 
estimating the cost of the various control options considered, but only 
provides sum total estimates of the capital costs and annual operating 
and maintenance costs without providing individual line items or 
calculations for review. Texas received comments during the State's 
public comment period on the proposed Texas RH SIP for the second 
planning period stating that the proposed SIP did not include proper 
documentation of the cost estimates of the various control measures, 
including the actual spreadsheets showing the calculations that inform 
the results of the cost analyses as part of the TCEQ's four-factor 
analysis.\156\ Despite these comments, Texas did not directly address 
why calculation spreadsheets and other necessary documentation of the 
cost analysis were omitted from the proposed SIP, nor did Texas make 
changes to the final SIP submittal or include adequate documentation of 
the cost analysis in the final SIP submittal in response to these 
comments. With respect to the capital and annual costs of scrubber 
upgrades, Texas provided one additional piece of information in its 
response stating that it relied on prior studies and work conducted on 
potential scrubbing system upgrades to estimate the capital and annual 
costs to inform total annualized costs.\157\ However, the response does 
not explain what ``prior studies and work conducted on potential 
scrubbing system upgrades'' it relied on or how it relied on those 
studies to estimate the capital and annual cost of scrubber upgrades. 
This documentation is critical to ensuring that Texas's consideration 
of cost of potential control measures, as required by the RHR and the 
CAA,\158\ was reasonable and based on sufficiently reliable 
information.\159\
---------------------------------------------------------------------------

    \155\ 40 CFR 51.308(f)(2)(iii).
    \156\ 2021 Texas Regional Haze Plan, Response to Comments at 
478-479 of 653.
    \157\ 2021 Texas Regional Haze Plan, Response to Comments at 479 
of 653.
    \158\ See 40 CFR 51.308(f)(2)(i) (``The State must evaluate and 
determine the emission reduction measures that are necessary to make 
reasonable progress by considering the costs of compliance . . .''); 
CAA 169A(g)(1) (``in determining reasonable progress, there shall be 
taken into consideration the costs of compliance . . .'').
    \159\ As discussed in the following section, the EPA requested 
the additional supporting information from Texas. In response, Texas 
provided additional files and spreadsheets to EPA upon request. 
However, the public did not have access to these files during the 
state-level comment period and therefore did not have an opportunity 
to review or comment on the complete technical basis of Texas's cost 
analyses.
---------------------------------------------------------------------------

    The EPA has recommended that costs of compliance and the remaining 
useful life should be calculated consistent with the methods set forth 
in the EPA's Control Cost Manual in order to allow for comparisons 
between different sources within a State, and cost analyses in other 
states.\160\ To that end, states relying on EPA's Control Cost Manual 
need only reference the manual as the documentation necessary to meet 
the requirements of the RHR to document the technical basis, including 
cost information, on which the State is relying.\161\ When a State uses 
cost methods other than the EPA's Control Cost Manual, it is necessary 
for those differences to be reasonable and sufficiently documented to 
meet the requirements of the RHR to document the technical basis, 
including cost information, on which the State is relying.\162\ In 
response to comments, Texas acknowledged that it deviated from EPA's 
Control Cost Manual in certain instances, but failed to provide 
adequate documentation and justification of its costs in light of its 
deviations.\163\
---------------------------------------------------------------------------

    \160\ 2019 Guidance at 31. As we have previously noted in 
relation to BART determinations, ``[w]ithout an `apples-to-apples' 
comparison of costs, it is impossible to draw rational conclusions 
about the reasonableness of the costs of compliance for particular 
control options. Use of the [Control Cost Manual] methodology is 
intended to allow a fair comparison of pollution control costs 
between similar applications for regulatory purposes.'' 77 FR 72512, 
72518.
    \161\ 2019 Guidance at 31.
    \162\ 40 CFR 51.308(f)(2)(iii); 2019 Guidance at 31.
    \163\ See 2021 Texas Regional Haze Plan, Response to Comments at 
472 of 653.
---------------------------------------------------------------------------

    One important element of a cost analysis is the remaining useful 
life of

[[Page 83361]]

the equipment. This is important because equipment life, while related 
to the ``remaining useful life'' factor of the four-factor analysis, 
also factors into the consideration of cost of compliance due to the 
annualization of cost in estimating the cost-effectiveness ($/ton 
reduced). The EPA's 2019 Guidance explains that, generally, states can 
consider the remaining useful life factor by considering the useful 
life of the control system.\164\ Typically, the remaining useful life 
of the source itself will be longer than the useful life of the 
emission control system under consideration. Thus, annualized costs of 
compliance are typically based on the useful life of the control 
equipment rather than the life of the source, unless the source is 
under an enforceable requirement to cease operation or otherwise reduce 
its emissions (i.e., switching from coal to natural gas).\165\
---------------------------------------------------------------------------

    \164\ See 2019 Guidance at 33.
    \165\ See 2019 Guidance at 33.
---------------------------------------------------------------------------

    The Control Cost Manual generally assumes a remaining useful life 
of equipment of 30 years for scrubbers and SCR.\166\ Texas, however, 
assumed a remaining useful equipment life of 15 years for all 
sources.\167\ Texas explained that some of the sources it evaluated in 
the four-factor analysis could not reasonably be expected to operate an 
additional 30 years,\168\ but that most could reasonably be expected to 
continue to operate longer than five years. Therefore, Texas determined 
that a remaining useful life of 15 years was a reasonable ``mid-point'' 
to use in the four-factor analysis. However, Texas did not provide any 
specific documentation to support its determination that all of the 
sources it selected could not reasonably expected to operate an 
additional 30 years nor did it point to any enforceable commitments to 
retire or otherwise reduce its emissions contained in the SIP. The 
selection of a 15-year useful life inflates the cost of controls 
because those costs are amortized over a shorter period of time, 
thereby increasing the calculated annualized cost and the cost-
effectiveness ($/ton reduced). This impacted Texas's identification of 
cost-effective controls and ultimately, their assessment of aggregate 
annualized costs. For example, Texas considered SCR as a potential 
NO<INF>X</INF> control for the Texarkana Mill.\169\ Using a 15-year 
equipment life resulted in an annualized capital cost for SCR on Boiler 
No. 2 of $853,383 and a cost effectiveness of $5,254 ($/ton).\170\ 
Using a 30-year equipment life resulted in an annualized capital cost 
of $688,550 and a cost effectiveness of $4,956 ($/ton).\171\ Because 
Texas used a cost-effectiveness threshold of $5,000, Texas did not 
further consider SCR for Boiler No. 2 in determining what measures may 
be necessary to include in the long-term strategy in order to make 
reasonable progress.\172\
---------------------------------------------------------------------------

    \166\ Equipment life can depend on the type of equipment. For 
example, the EPA's Control Cost Manual provides for an assumed 30 
year equipment life for scrubbers, but a 20 year equipment life for 
SNCR. The Control Cost Manual and associated spreadsheets are 
available at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution, 
select portions of which are included in the docket for this action.
    \167\ 2021 Texas Regional Haze Plan, appendix B at B-14--B-15.
    \168\ We are aware that Pirkey and Oklaunion have ceased 
operations. However, the EPA is not aware that these permits have 
been voided. We are also aware that other sources such as Coleto 
Creek and Welsh have publicly stated an intention to retire or 
convert to natural gas. Coleto Creek has announced its anticipated 
retirement in 2027 and Welsh has announced that it will convert to 
natural gas by 2028. These announcements are not an enforceable 
commitment to retire the units by a date certain and Texas has not 
asked to make those retirements federally enforceable and permanent 
by including them in the SIP. Therefore, when considering the fourth 
statutory factor, these announcements cannot be used to shorten the 
remaining useful life of the sources. See Vistra Announces Plans to 
Add Up to 2,000 MW of Gas-Fueled Dispatchable Power in ERCOT 
available at https://investor.vistracorp.com/2024-05-30-Vistra-Announces-Plans-to-Add-Up-to-2,000-MW-of-Gas-Fueled-Dispatchable-Power-in-ERCOT; AEP Schedule of Closures available at https://aepcommunitytransition.com/closures/.
    \169\ 2021 Texas Regional Haze Plan, appendix B at B-28.
    \170\ 2021 Texas Regional Haze Plan, appendix B at B-28.
    \171\ 2021 Texas Regional Haze Plan, appendix B at B-28.
    \172\ 2021 Texas Regional Haze Plan, appendix B at B-28. The 
difference in emission reductions between SCR and low-NO<INF>X</INF> 
burners is 277 tpy.
---------------------------------------------------------------------------

    Another important element of the cost analysis is the interest rate 
used. According to the EPA's Control Cost Manual, if a company-specific 
interest rate is not available for use in evaluating the cost of 
controls in the four-factor analysis, the use of the current bank prime 
rate is the appropriate default.\173\ The bank prime rate is reflective 
of the typical rate for borrowing among large firms. The bank prime 
rate was 3.25 percent for at least six months leading up to Texas's 
public comment period,\174\ and remained so when Texas submitted the 
final SIP to the EPA in July 2021.\175\ Texas instead used a 10 percent 
interest rate, assuming that industrial sources could not obtain the 
bank prime rate. However, Texas did not provide any documentation to 
support this general assertion. In addition, the use of the higher 10 
percent interest rate serves to increase the total annualized cost.
---------------------------------------------------------------------------

    \173\ The EPA Air Pollution Control Cost Manual (the Control 
Cost Manual, or Manual), (November 2017), section 1, Chapter 2 at 
16. The Control Cost Manual is available at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution.
    \174\ We acknowledge that the current bank prime rate is higher 
than the rate at the time Texas submitted its SIP, however, at no 
point has the bank prime rate reached 10 percent. A historical 
record of the bank prime rates is available at https://fred.stlouisfed.org/series/PRIME. Texas's public comment period on 
the proposed 2021 Texas Regional Haze Plan for the second planning 
period took place from October 9, 2020, to January 8, 2021.
    \175\ See Bank Prime Loan Rate Changes: Historical Dates of 
Changes and Rates available at https://fred.stlouisfed.org/series/PRIME. See also The EPA's Control Cost Manual, section 1, Chapter 2 
titled ``Cost Estimation: Concepts and Methodology,'' at 16.
---------------------------------------------------------------------------

    Finally, based on Texas's response to comments, Texas included 
certain costs inconsistent with the ``overnight'' cost methodology used 
in the EPA's Control Cost Manual, which resulted in increased costs for 
the control options considered. However, it is unclear from the 
information included in Texas's SIP submission, how and for which 
sources Texas included these costs. In the absence of adequate 
documentation and justification to support the basis for its cost 
analysis, we find that Texas's cost analyses are not sufficiently 
reliable to support its control determinations.
    Thus, we find that Texas did not adequately document the technical 
basis and cost information on which it based its evaluation of the cost 
of compliance of controls, which is a RHR requirement under 40 CFR 
51.308(f)(2)(iii). Without this information, it is unclear how Texas's 
methodology results in a long-term strategy that includes all measures 
necessary for reasonable progress in the Second Planning Period.
ii. Texas's Cost Analysis for Scrubber Upgrades Was Unsupported and 
Unreasonable
    Texas's cost analysis of SO<INF>2</INF> scrubber upgrades for EGUs 
was unreasonable because many assumptions made by Texas in estimating 
the cost of scrubber upgrades were inadequately justified and based on 
outlier information that led to unreliable and inflated cost estimates. 
As explained in the previous section, the 2021 Texas Regional Haze Plan 
did not document or adequately explain Texas's methodology for 
estimating the capital costs and operation and maintenance costs of 
scrubber upgrades, which is a requirement under 40 CFR 
51.308(f)(2)(iii).\176\ Rather, the 2021

[[Page 83362]]

Texas Regional Haze Plan merely provided an ``example'' which indicates 
that the average capital cost of wet scrubber upgrades is $37.84/kW and 
the average operating and maintenance cost is $3.09/kW-year for a 537 
MW EGU.\177\ The significance of the example provided in the 2021 Texas 
Regional Haze Plan is unclear. An examination of the total capital 
costs included in the 2021 Texas Regional Haze Plan reveals that Texas 
did not use an assumption of $37.84/kW to estimate capital costs of 
scrubber upgrades, and in fact used a cost assumption that was over 
three times higher than the referenced ``average'' value. To 
illustrate, Texas estimated the capital cost of scrubber upgrades at 
AEP Pirkey Unit 1 to be $99,921,030, as shown in table 9. This capital 
cost estimate is not the equivalent of $37.84/kW, but rather $138.59/
kW. In examining the other scrubber upgrades, Texas applied the 
$138.59/kW to all scrubber upgrade estimates.\178\ Thus, the example 
provided by Texas indicating that the average capital cost of wet 
scrubber upgrades is $37.84/kW is misleading and an inaccurate 
representation of Texas's methodology for estimating the capital cost 
of wet scrubber upgrades.\179\
---------------------------------------------------------------------------

    \176\ A spreadsheet that documents Texas's cost analysis of 
scrubber upgrades was provided by the TCEQ to the EPA at our request 
during the State's public comment period on the proposed Texas RH 
SIP for the second planning period. However, this spreadsheet was 
not included in the proposed Texas RH SIP, nor in the final SIP 
submitted to the EPA. Thus, the public did not have an opportunity 
to review or comment on the complete technical basis of Texas's cost 
analysis of scrubber upgrades. We discuss these deficiencies in 
Texas's cost analysis of scrubber upgrades in greater detail in the 
paragraphs that follow. This spreadsheet is included in the docket 
for this action (scrubber upgrades.xlsx).
    \177\ See 2021 Texas Regional Haze Plan, appendix B at B-13.
    \178\ The example provided by Texas for estimating annual 
operating and maintenance costs of scrubber upgrades is also 
misleading. For example, Texas's estimated annual operating and 
maintenance cost of scrubber upgrades for AEP Pirkey Unit 1 is 
$2,740,188, as shown in Table 9. This is the equivalent of $3.80/kW-
year.
    \179\ The only other information Texas provides about its 
scrubber upgrade analysis is in appendix B of the 2021 Texas 
Regional Haze Plan. Specifically, Texas includes the following 
statement in discussing the scrubber upgrades analysis for AEP 
Pirkey Unit 1: The Western Regional Air Partnership (WRAP) data for 
potential scrubber upgrades and a WRAP spreadsheet from August 2010 
containing data for EGUs with proposed Best Available Retrofit 
Technology SO<INF>2</INF> controls were relied on for information 
(also included in the docket for this action). The spreadsheet data 
indicated the greatest increase in scrubbing system efficiency an 
existing system could achieve, from baseline levels, was 95%. 
Therefore, the TCEQ evaluated a potential system upgrade from 79% to 
95%. See 2021 Texas Regional Haze Plan, appendix B at B-4. However, 
it is unclear based on the 2021 Texas Regional Haze Plan itself 
whether the WRAP data and spreadsheet were in any way used to 
estimate the capital costs and annual operating and maintenance 
costs of wet scrubber upgrades. Furthermore, this statement was only 
included in Texas's discussion of the scrubber upgrades analysis for 
AEP Pirkey Unit 1 but not specifically mentioned in the discussion 
of scrubber upgrades for other EGUs.
---------------------------------------------------------------------------

    Because Texas did not include adequate documentation of its cost 
analysis, the EPA requested additional supporting information and data 
from Texas regarding its technical analyses to aid in our review. In 
response to this request, the Texas provided additional files to the 
EPA, including Excel spreadsheets, that were not made available to the 
public during Texas's public comment period and were not included in 
the final SIP submitted to the EPA.\180\ One of these files is an Excel 
spreadsheet that documents and provides additional information on 
Texas's methodology for estimating the capital costs and annual 
operating and maintenance costs of scrubber upgrades.\181\ Reviewing 
the spreadsheet demonstrates Texas's cost methodology relied on certain 
cost assumptions based on outlier information.\182\
---------------------------------------------------------------------------

    \180\ See ``scrubber upgrades.xlsx'' included in the docket for 
this action. See also, additional source specific cost spreadsheets 
from Texas available in the docket for this action.
    \181\ scrubber upgrades.xlsx.
    \182\ TCEQ also used the outlier value to estimate the cost of 
upgrading the scrubbers at the Holcim cement facility from 90% to 
95% control efficiency. These costs are also likely an over 
estimation for the same reasons as explained later in this section.
---------------------------------------------------------------------------

    The files documenting the scrubber upgrades analysis confirm that 
Texas used an assumption of $139/kW to calculate the capital costs of 
scrubber upgrades. This $139/kW assumption is the highest capital cost 
$/kW value out of several scrubber upgrades cost estimates for EGUs 
compiled from a National Park Service (NPS) spreadsheet from 2010 found 
on the Western Regional Air Partnership (WRAP) legacy website and 
relied upon by Texas.\183\ Furthermore, this $139/kW assumption is an 
outlier value, which corresponds to upgrades at the Coal Creek Power 
Plant in North Dakota.\184\ The costs for upgrades at this facility 
included additional project elements other than upgrades to the 
existing scrubber, such as coal drying.\185\ Texas did not explain why 
using cost assumptions from a project, which included additional coal 
pre-treatment project costs like coal drying, is appropriate or 
reasonable in estimating the capital costs of the scrubber upgrades it 
was considering. The next highest capital cost $/kW value included in 
the spreadsheet is an upgrade project that was estimated to cost 
$52.39/kW.\186\ The average $/kW capital costs provided in the 
spreadsheet, even including the $139/kW outlier is approximately $38/
kW, with costs as low as $4/kW for some units.\187\ Scrubber upgrade 
costs are site-specific, depending on existing scrubber design and 
available upgrades.\188\ Therefore, it is inappropriate to rely on cost 
assumptions that are based on outliers, especially absent any 
discussion of why the higher cost is more reflective of upgrades 
necessary at a particular source, because they are not representative 
of the anticipated cost of scrubber upgrades at these units. Had Texas 
instead relied on the average capital cost found in the spreadsheet, 
and presented as the example calculation in its SIP, the capital costs 
contained in the SIP would have been significantly lower.
---------------------------------------------------------------------------

    \183\ See ``scrubber upgrades.xlsx''; see also 2010 NPS EGUs 
With Proposed BART SO<INF>2</INF> Controls Spreadsheet available in 
the docket.
    \184\ 2010 NPS EGUs With Proposed BART SO<INF>2</INF> Controls 
Spreadsheet available in the docket.
    \185\ See Great River Energy Coal Creek BART Emission Control 
Cost Analysis. The report is available in the docket for this 
action.
    \186\ See ``scrubber upgrades.xlsx'' available in the docket for 
this action.
    \187\ See ``scrubber upgrades.xlsx'' available in the docket for 
this action.
    \188\ For example, costs to upgrade scrubber performance from 
94-95% at San Miguel might only require increased reagent use, 
whereas scrubber upgrades at less efficient units may require more 
significant equipment upgrades or elimination of scrubber bypasses, 
as demonstrated by the range in costs in the NPS dataset.
---------------------------------------------------------------------------

    To illustrate this point, the EPA recalculated the scrubber upgrade 
costs for Martin Lake, San Miguel, and Pirkey using the average capital 
cost \189\ as well as the average operation and maintenance costs 
contained in Texas's Excel spreadsheet and identified in their example 
calculation in appendix B of the 2021 Texas Regional Haze Plan.\190\ 
EPA focused on these three sources as these were the scrubber upgrades 
that Texas identified as meeting its cost-effectiveness threshold of 
$5,000/ton. These recalculated values are found in table 18.
---------------------------------------------------------------------------

    \189\ By providing this illustration, the EPA is not necessarily 
endorsing the use of the average capital cost to calculate the cost 
of scrubber upgrades at a source. Given the site-specific nature of 
scrubber upgrades, the use of the average capital cost of several 
scrubber upgrades may not accurately reflect the cost to upgrade any 
particular scrubber.
    \190\ See ``EPA modified RH-2021-Summary Emissions, Cost 
Table.xlsx'' and ``EPA modified-scrubber upgrades.xlsx'' 
spreadsheets. Available in the docket for this action.

[[Page 83363]]



                                                                   Table 18--TCEQ vs. EPA Recalculated Scrubber Upgrade Costs
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                           Capital costs        15 Year life total annual                   15 year life cost
                                                                  2018 EIA electric  capacity/2016 ----------------------------            cost             Emissions     effectiveness ($/ton)
            Company/site name                       Unit            EI capacity or engine rating                               ---------------------------   removed   -------------------------
                                                                                                        TCEQ          Avg.          TCEQ          Avg.        (tpy)         TCEQ         Avg.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
American Electric Power/Pirkey Power       Unit 1...............  721 MW..........................   $99,921,030   $27,279,969   $15,877,183   $5,817,383        3,874       $4,098       $1,502
 Plant.
NRG Energy/Limestone Elec. Gen. Station..  Unit 1...............  893 MW..........................   123,757,947    33,787,812    19,664,805    7,205,163        3,212        6,123        2,244
                                           Unit 2...............  957 MW..........................   132,627,498    36,209,335    21,074,153    7,721,546        3,259        6,467        2,370
Vistra Energy/Martin Lake Electrical       Unit 1...............  793 MW..........................   109,899,275    30,004,182    17,462,700    6,398,313       16,172        1,080          396
 Station.                                  Unit 2...............  793MW...........................   109,899,275    30,004,182    17,462,700    6,398,313       14,101        1,238          454
                                           Unit 3...............  793MW...........................   109,899,275    30,004,182    17,462,700    6,398,313       16,458        1,061          389
San Miguel Electric Cooperative/San        Unit 1...............  410 MW..........................    56,820,558    15,512,881     9,028,634    3,308,081        2,001        4,512        1,653
 Miguel Electric Plant.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on this information, and utilizing Texas's selected 15-year 
remaining useful life assumption, the 15-year total annual costs for 
scrubber upgrades at these three facilities decrease from $77,293,916 
to $28,320,403, a reduction in total annual costs of $48,973,513. If 
the outlier value was excluded in determining the average capital cost, 
the total annualized costs would be even lower. Thus, the reliance on 
this outlier value in estimating the capital costs significantly 
inflates the total annualized costs provided in the 2021 Texas Regional 
Haze Plan. Without an explanation as to why this was reasonable, this 
reliance is unjustified. Furthermore, had Texas used the average 
capital cost, the costs of upgrading the scrubbers at both units at 
Limestone would have been below its $5,000/ton cost-threshold. Based on 
Texas's analysis, upgrading the controls on both units at Limestone 
would result in a reduction in over 6,400 \191\ tpy of SO<INF>2.</INF> 
The inflation of total annualized costs is also important, as discussed 
later in the notice, because Texas relies on the combined total 
annualized costs of control measures in part to determine that no 
additional measures are necessary to include in its long-term strategy 
to make reasonable progress.\192\
---------------------------------------------------------------------------

    \191\ See 2021 Texas Regional Haze Plan, appendix B, at B-20.
    \192\ We provide additional discussion regarding the cost of 
scrubber upgrades in the TSD for this action, provided in the 
docket.
---------------------------------------------------------------------------

    We are proposing to find that Texas's cost analysis of 
SO<INF>2</INF> scrubber upgrades for EGUs does not meet the 
requirements under 40 CFR 51.308(f)(2)(iii) to document the technical 
basis, including costs, that the State is relying on to determine the 
emission reduction measures that are necessary to make reasonable 
progress. Furthermore, in estimating the cost of scrubber upgrades as 
part of its four-factor analysis, many assumptions made by Texas were 
not adequately justified, and thus unreasonable, as it resulted in 
inflated and unreliable cost estimates. Because of these flaws, we find 
that Texas did not reasonably consider the cost of compliance as 
required by the RHR and CAA.\193\
---------------------------------------------------------------------------

    \193\ See CAA 169(g)(1); 40 CFR 51.308(f)(2).
---------------------------------------------------------------------------

c. Time Necessary for Compliance
    In its 2021 Regional Haze Plan, despite the time necessary for 
compliance being one of the four statutory factors a State must 
consider when determining what control measures are necessary for 
reasonable progress,\194\ Texas stated in its submission that the time 
necessary for compliance was not a critical factor in the determination 
of applicable additional controls for Texas sources.\195\ That being 
said, Texas determined that the time necessary for a source to design, 
build, and install SO<INF>2</INF> scrubbing technology would be 
approximately three years and that the time necessary to build and 
commence operation of DSI technology could be less given that scrubbing 
vessels would not need to be constructed.\196\ Texas also assumed that 
the time to design, build, and install NO<INF>X</INF> control 
technologies would be approximately three years. While we are proposing 
to disapprove Texas's long-term strategy for the reasons provided 
elsewhere in Section IV.E of this notice, we note that Texas's 
assumptions of the time necessary for compliance for the controls 
evaluated are reasonable.
---------------------------------------------------------------------------

    \194\ See CAA 169A(g)(1); 40 CFR 51.308(f)(2)(i).
    \195\ 2021 Texas Regional Haze Plan at 7-13.
    \196\ 2021 Texas Regional Haze Plan at 7-13.
---------------------------------------------------------------------------

d. Energy and Non-Air Quality Environmental Impacts of Compliance
    Where quantifiable for a particular control option, energy impacts 
of compliance are reflected in the cost estimate and were considered by 
Texas under the cost of compliance factor.\197\ For instance, 
electricity costs necessary to operate fans, pumps, and other ancillary 
equipment as well as waste disposal costs were factored into the cost 
of compliance calculations for dry and wet scrubbers, DSI systems, SCR 
systems, and SNCR systems.\198\ Texas stated that control systems that 
require only modifications to alter fuel-air mixing and combustion 
temperatures are not expected to have additional electricity or steam 
demands or to generate wastewater or solid waste.\199\ For reasons 
explained throughout section IV.E we are proposing to disapprove 
Texas's long-term strategy.
---------------------------------------------------------------------------

    \197\ 2021 Texas Regional Haze Plan at 7-13.
    \198\ 2021 Texas Regional Haze Plan at 7-13.
    \199\ 2021 Texas Regional Haze Plan at 7-14.
---------------------------------------------------------------------------

e. Remaining Useful Life
    As we have discussed in detail in section IV.E.2.b. of this 
proposed rule, we disagree with Texas's generalized assumption of a 15-
year equipment life. Without additional discussion explaining why the 
EGUs and non-EGUs evaluated in the four-factor analysis could not be 
expected to operate more than 15 years or a federally enforceable 
commitment to cease operations or otherwise reduce emissions at these 
units within 15 years, Texas's generalized assumption of a 15-year 
equipment life is not reasonable and results in the overestimation of 
the annualized capital costs and the cost-effectiveness of controls.
f. Texas's Control Determinations
    After characterizing the four statutory factors, States must 
consider and weigh the factors to determine what control measures are 
necessary to include in its long-term strategy to make reasonable 
progress.\200\ In determining what control measures were necessary to 
make reasonable progress, Texas weighed the costs of compliance factor 
and projected visibility benefits of potential controls. Specifically, 
Texas relied on both the total annualized costs of controls in

[[Page 83364]]

considering the costs of compliance, which it calculated was over $200 
million, and the ``less than perceptible visibility benefit'' it 
projected in determining that no additional control measures were 
necessary to include in its long-term strategy to make reasonable 
progress.\201\
---------------------------------------------------------------------------

    \200\ See CAA 169A(g)(1); CAA 169A(B)(2)(b).
    \201\ 2021 Texas Regional Haze Plan table 7-4 at 7-16 to 7-17.
---------------------------------------------------------------------------

    Texas derived the total annualized cost by adding together the 
annualized costs of controls at each source that met its $5,000/ton 
cost effectiveness threshold. Table 19 presents a summary of the 
estimated total annualized cost of the controls that met Texas's 
$5,000/ton threshold.\202\
---------------------------------------------------------------------------

    \202\ 2021 Texas Regional Haze Plan table 7-4 at 7-14.

                           Table 19 \203\--Texas's Potential Control Strategy Summary
----------------------------------------------------------------------------------------------------------------
                                                              Total emissions reductions      Estimated total
                         Pollutant                                    (tons/yr)               annualized cost
----------------------------------------------------------------------------------------------------------------
NOX.......................................................                          3,171             $9,335,087
SO2.......................................................                         79,285            195,539,404
                                                           -----------------------------------------------------
    Total Costs...........................................  .............................            204,874,491
----------------------------------------------------------------------------------------------------------------

    In conjunction with total annualized costs, Texas also considered 
the potential visibility benefits of controls by conducting three 
different photochemical modeling sensitivity runs representing 
different control scenarios. Similar to how it calculated the total 
annualized costs, Texas only included those control measures at sources 
for which the cost of the control measures met the $5,000/ton threshold 
for NO<INF>X</INF> or SO<INF>2</INF>.\204\ While Texas's 2021 Regional 
Haze Plan did not specifically identify (in Chapter 7 or Chapter 8 of 
its SIP) which sources or control measures were actually included in 
the sensitivity modeling, the information the TCEQ included in 
PowerPoint presentations used for consultation indicates control 
measures for 11 out of the 18 sources selected for evaluation under the 
four factor analysis were included in the sensitivity modeling.\205\ 
Each sensitivity scenario reduced NO<INF>X</INF> and/or SO<INF>2</INF> 
emissions at specific EGU and non-EGU sources for the modeled 2028 
scenario.\206\ Scenario 1 \207\ involved the removal of emissions from 
the Oklaunion Power Station as its owners had announced its retirement 
in 2020. Scenario 2 \208\ included SO<INF>2</INF> reductions at all 
units with identified cost-effective SO<INF>2</INF> controls in 
addition to Scenario 1. Scenario 3 \209\ included NO<INF>X</INF> 
reductions at all units with identified cost-effective NO<INF>X</INF> 
controls in addition to Scenario 2. We note that the additional 
visibility improvements provided by the inclusion of NO<INF>X</INF> 
controls in Scenario 3 provided little additional visibility benefit on 
the average across the 20 percent most impaired days, yet the 
associated costs of these controls resulted in several millions of 
dollars being included in the total annual costs Texas calculated in 
its 2021 Texas Regional Haze Plan.\210\ The results of this modeling 
analysis were used to estimate the overall visibility benefit these 
controls would have on the 20 percent most impaired days at the Class I 
areas impacted by Texas's emissions. The projected visibility 
improvements at Class I areas impacted by Texas sources under Scenario 
3 are presented in table 20.\211\
---------------------------------------------------------------------------

    \203\ This table does not reflect NO<INF>X</INF> costs and 
associated emission reductions from the Oklaunion facility. See 2021 
Texas Regional Haze Plan at 7-15.
    \204\ 2021 Texas Regional Haze Plan at 7-14.
    \205\ 2021 Texas Regional Haze Plan, appendix A at 71-74 of 227. 
This appendix also provides a table that shows which units and 
control measures were included in its sensitivity modeling. While 
Texas's analysis found that certain control measures at Oklaunion 
Power Station were above its $5,000/ton threshold, Texas also 
included the shutdown of the facility in its sensitivity modeling 
rather than potential control measures. 2021 Texas Regional Haze 
Plan at 7-15.
    \206\ See 2021 Texas Regional Haze Plan, Section 8.5. More 
general information can be found in section 7.2.2.3.
    \207\ Texas refers to this Scenario as ZeroOKU.
    \208\ Texas refers to this Scenario as ZeroOKU&SO<INF>2</INF>.
    \209\ Texas refers to this Scenario as 
ZeroOKU&SO<INF>2</INF>&NO<INF>X</INF>.
    \210\ See 2021 Texas Regional Haze Plan at 8-64.
    \211\ 2021 Texas Regional Haze Plan table 7-6 at 7-16.
    \212\ The visibility improvements presented in the table reflect 
Scenario 3.

Table 20--Texas's Estimated Haze Index Improvements for Affected Class I
                               Areas \212\
------------------------------------------------------------------------
                                                Haze index improvement
                Class I area                             (dv)
------------------------------------------------------------------------
Big Bend....................................                        0.07
Caney Creek.................................                        0.56
Guadalupe Mountains.........................                        0.03
Salt Creek..................................                        0.07
Upper Buffalo...............................                        0.21
White Mountain..............................                        0.02
Wichita Mountains...........................                        0.23
------------------------------------------------------------------------

    Texas ultimately determined that any visibility benefit for each 
Class I area would be ``imperceptible.'' Thus, combining the 
``imperceptible'' projected visibility benefit for each Class I area 
with the corresponding total annual costs associated with the controls 
included in the modeled control strategy, Texas concluded that no 
additional control measures were necessary to make reasonable progress. 
As discussed below, the EPA finds Texas's conclusion to be unjustified, 
unreasonable, and inconsistent with the CAA and the RHR.
i. Texas's Consideration of Costs To Support Its Determination That No 
Additional Measures Are Necessary To Make Reasonable Progress Was 
Unjustified and Unreasonable
    Texas determined that the total annualized cost of controls of

[[Page 83365]]

approximately $205 million was too high, but provided no context or 
support as to why total annualized cost was an appropriate decision 
metric in consideration of the cost of compliance, what range of total 
annualized cost would be reasonable, and why $205 million was not 
reasonable. While the RHR does allow for the evaluation of sources on 
either a source-by-source basis or based on the evaluation of groups of 
sources, in almost any case, a State could, as Texas has here, 
aggregate the annualized control costs for a large number of sources 
such that the State could find the total cost to be ``too expensive;'' 
and therefore, determine that no additional controls are necessary to 
make reasonable progress. This is especially true in States like Texas 
given the vast number of sources in the State and the number of Class I 
areas impacted by the emissions from these sources. Thus, a reasonable 
source selection for a State like Texas would necessarily identify 
several sources for evaluation of potential control measures for which 
total annualized costs would end up being ``large.'' Therefore, it is 
unsurprising that Texas found that total annualized costs of controls 
were over $200 million; however, without a relative scale to compare 
against, this $200 million figure is meaningless and does not 
necessarily support Texas's determination that no control measures are 
necessary for inclusion in its long-term strategy to make reasonable 
progress. This concern is supported by EPA's 2019 Guidance which states 
that, ``EPA does not believe it is reasonable to solely use a threshold 
for the capital cost or annualized cost to determine that a measure is 
not necessary to make reasonable progress. Large capital costs 
considered in isolation may not provide complete information about the 
potential reasonableness of a measure . . .'' \213\ Furthermore, if 
this approach were replicated in each successive planning period, no 
controls would ever be found to be cost-effective and necessary to make 
reasonable progress, which would result in no long-term strategy. 
Rather, all that can be determined from Texas's use of the total 
annualized cost is that it represents the sum total of the costs of 
controls for a group of sources that impact one or more Class I areas 
in Texas or nearby States. Therefore, Texas's use of total annualized 
cost was unjustified and unreasonable.
---------------------------------------------------------------------------

    \213\ 2019 Guidance at 39.
---------------------------------------------------------------------------

    In addition to failing to justify how consideration of total 
annualized cost was reasonable, Texas also failed to explain and 
justify the apparent contradiction between considering controls to be 
cost effective on a source specific basis using a threshold of $5,000/
ton, but then dismissing those same controls as too costly when 
presented as total annualized costs. The need to support and justify 
this apparent contradiction is critical considering that Texas selected 
its $5,000/ton cost effectiveness threshold to ``identif[y] the 
potential control measures for each source that could be applied in a 
cost-effective manner,'' \214\ and thus eliminate those control 
measures which they deemed too costly. Texas's reliance on the total 
annual costs of all controls considered cannot outweigh or otherwise 
negate the fact these controls were all below Texas's selected cost-
effectiveness threshold of $5,000/ton. Furthermore, we note that the 
controls that make up this total annualized cost have an average $/ton 
cost-effectiveness of less than $2,500/ton SO<INF>2</INF> reduced and 
less than $3,000/ton for NO<INF>X</INF> reduced.
---------------------------------------------------------------------------

    \214\ See 2021 Texas Regional Haze Plan at 7-14.
---------------------------------------------------------------------------

    Additionally, while the EPA finds that Texas's use of total 
annualized costs was unjustified and unreasonable, even if such a 
metric were appropriate, Texas's total annualized cost of approximately 
$205 million included unreasonable costs associated with the scrubber 
upgrades it evaluated. As previously explained in section IV.E.2.b, 
Texas's calculation of the costs associated with upgrading the 
scrubbers at Martin Lake, Pirkey, and San Miguel used an unsupported 
outlier value in determining the costs, which resulted in an inflated 
cost estimation. Had Texas used the average costs rather than the 
outlier value, the total annualized cost of the scrubber upgrades would 
have decreased by approximately $49 million, and the total annualized 
cost of controls would have decreased from approximately $205 million 
to $156 million.\215\ Thus, this one decision significantly and 
unreasonably inflates the total annualized cost. Even assuming the 
total annualized cost metric is a reasonable way of considering costs, 
because Texas failed to describe or justify why $205 million was too 
high, and what range of costs would be reasonable, we cannot determine 
whether Texas would have found this lower total annualized cost 
reasonable such that the measures are necessary for inclusion in its 
long-term strategy to make reasonable progress. Thus, the EPA finds 
that Texas failed to justify how its use of total annualized costs to 
dismiss controls was reasonable and consistent with the CAA and RHR 
requirement to include those measures necessary to make reasonable 
progress in its long-term strategy.
---------------------------------------------------------------------------

    \215\ See ``EPA modified-RH 2021-Summary Emissions, Cost 
Table.xlsx'' available in the docket for this action.
---------------------------------------------------------------------------

ii. Texas's Reliance on the Lack of Perceptible Visibility Benefits To 
Support Its Determination That No Additional Measures Are Necessary Was 
Unreasonable and Inconsistent With the CAA and the RHR
    Texas's determination that visibility benefits are only meaningful 
if it results in a perceptible change in visibility was unjustified and 
unreasonable. As previously explained, after identifying which of the 
18 sources selected for further analysis using the four statutory 
factors had potential control measures meeting the $5,000/ton cost-
effectiveness threshold for NO<INF>X</INF> or SO<INF>2</INF>, those 
emission reductions associated with those control measures were then 
included in the photochemical modeling sensitivity runs conducted by 
the TCEQ. The projected visibility benefits are presented in table 20. 
Because the results of the modeling analysis showed that the visibility 
benefit of the modeled control strategy for each Class I area fell 
within a range that was ``imperceptible,'' (which Texas defines as less 
than 1.0 deciview), Texas found that this amount of visibility 
improvement was too small to support requiring any additional control 
measures for purposes of making reasonable progress during this 
planning period.
    The CAA and RHR are clear that the four statutory factors must be 
considered when determining the enforceable emissions limitations, 
schedules of compliance, or other measures that are necessary for 
reasonable progress toward meeting the national goal.\216\ As the EPA 
has previously explained, while visibility may be considered along with 
the four statutory factors, it must be done in a reasonable way.\217\ 
For example, visibility modeling can be used to compare the visibility 
benefits of cost-effective controls selected through four-factor 
analysis to determine which controls produce the greatest visibility 
benefits compared to their costs, or prioritizing which among several 
sources should install controls during a planning period.\218\ Nowhere 
in the statute or regulations is there a requirement that control 
measures produce perceptible visibility

[[Page 83366]]

improvements to be considered necessary to make reasonable progress at 
a particular Class I area; therefore, consideration of visibility 
benefits cannot outweigh the results of the analysis based on the four 
factors explicitly prescribed in statute.\219\ Furthermore, if a State 
uses a visibility benefit threshold to evaluate control measures, it 
must explain how its approach is consistent with the requirement to 
consider the statutory factors in making reasonable progress 
determinations. Texas did not explain how the use of perceptibility as 
a threshold to assess visibility benefits is consistent with the 
requirement to make reasonable progress.
---------------------------------------------------------------------------

    \216\ See CAA 169A(g)(1); 40 CFR 51.308(f)(2).
    \217\ 2021 Clarifications Memo at 14; see 2019 Guidance at 36-
37.
    \218\ 2021 Clarifications Memo at 12-13.
    \219\ See CAA 169A(g)(1).
---------------------------------------------------------------------------

    Section 169A(a) of the CAA establishes as a national goal the 
``prevention of any future, and the remedying of any existing, 
impairment of visibility in mandatory Class I Federal areas which 
impairment results from manmade air pollution.'' Nowhere in the CAA or 
the RHR is there a requirement to make a minimum amount of visibility 
improvement in determining that potential control measures are 
necessary to make reasonable progress. Rather, States are to make 
``reasonable progress'' towards natural visibility conditions every 
planning period. What is necessary for reasonable progress, as 
described throughout this section and this notice, is determined by a 
consideration of the four statutory factors. To that end, the EPA has 
reiterated that visibility thresholds used for BART and other analyses 
in the first planning period (e.g., 0.5 deciviews or 1 dv) are, in most 
cases, not appropriate thresholds for evaluating the impact of controls 
for reasonable progress in the second planning period and beyond.\220\ 
This is because regional haze is visibility impairment that is caused 
by the emission of air pollutants from numerous anthropogenic sources 
located over a wide geographic area.\221\ At any given Class I area, 
hundreds or even thousands of individual sources may contribute to 
regional haze.\222\ This necessarily means that to meet Congress's goal 
of preventing any future, and addressing any existing impairment, 
States must address these numerous sources of manmade air pollution 
which cause visibility impairment at Class I areas. Given the iterative 
nature of the regional haze program, evaluation of control measures for 
relatively smaller sources (with commensurate smaller visibility 
benefits) will be needed to continue making reasonable progress towards 
the national goal. As such, states should consider the magnitude of 
modeled visibility impacts or benefits in the context of its own 
contribution to visibility impairment. That is, whether a particular 
visibility impact or change is ``meaningful'' should be assessed in the 
context of the individual state's contribution to visibility 
impairment. At several Class I areas that Texas evaluated in its 2021 
Regional Haze Plan, sulfate was the largest cause of anthropogenic 
visibility impairment, with the largest contribution coming from Texas 
anthropogenic sources.\223\ Texas's own modeling also showed that, for 
multiple Class I areas, relative to the home State in which the Class I 
area is located, Texas's contribution to sulfate concentrations at the 
Class I area was more than the home State itself. For example, Texas's 
sulfate contribution at Caney Creek is nine times the amount of 
Arkansas's contribution (Texas anthropogenic contribution to 
particulate sulfate is 40.81 percent compared to Arkansas's 
anthropogenic contribution of 4.4 percent).<SUP>224 225</SUP> At 
Wichita Mountains, Texas's sulfate contribution is over four times 
Oklahoma's contribution.\226\ Yet, by using a threshold of 
perceptibility, Texas found that despite these impacts, the visibility 
benefits were too small to warrant requiring any additional control 
measures to make progress towards reducing this contribution. Such an 
approach is unreasonable as the approach results in maintaining 
significant visibility impairment in contradiction to Congress's 
expressly stated goal of remedying manmade impairment.\227\ This 
concern in part is why the EPA has explained that ``the existence of an 
impact above a perceptibility threshold is not a statutory or 
regulatory factor to be used when determining whether a source or 
sources contribute to visibility impairment or when determining 
measures needed for reasonable progress.'' \228\ Thus, Texas's 
determination that the lack of perceptible visibility benefits weighed 
in favor of its determination that no additional measures were 
necessary was unreasonable and failed to result in a long-term strategy 
that encompassed all of the measures necessary to make reasonable 
progress in the second planning period.
---------------------------------------------------------------------------

    \220\ Responses to Comments on Protection of Visibility: 
Amendments to Requirements for State Plans, at pg. 268; Final Rule 
82 FR 3078 (Jan. 10, 2017). The document is available in the 
following docket EPA-HQ-OAR-2015-0531; 2019 Guidance, at pg. 38-39.
    \221\ 40 CFR 51.301.
    \222\ 82 FR 3078, 3093 (Jan. 10, 2017).
    \223\ See 2021 Texas Regional Haze Plan, appendix F, section 
1.2.4.
    \224\ 2021 Texas Regional Haze Plan at 8-52 (``The results 
indicate that for the 13 Class I areas evaluated outside of Texas, 
the Texas influence for particulate sulfate is greater than the CIA 
home state influence for nine of the areas, with the largest 
influence ratio for Caney Creek in Arkansas, at 9.27, as highlighted 
in yellow in table 8-41. The Texas influence on particulate nitrate 
is larger for six sites, with a maximum ratio of 3.45 for Carlsbad 
Caverns in New Mexico, as highlighted in pink. Six sites have a 
larger Texas influence for both particulate sulfate and nitrate: 
Carlsbad Caverns, Bosque del Apache, Salt Creek, and White Mountain 
in New Mexico; and Caney Creek and Upper Buffalo in Arkansas.'').
    \225\ 2021 Texas Regional Haze Plan, appendix F, Figure 1-74 at 
F-75.
    \226\ 2021 Texas Regional Haze Plan table 8-41 at 8-53.
    \227\ See CAA 169A(a)(1).
    \228\ Responses to Comments on Protection of Visibility: 
Amendments to Requirements for State Plans, at 268; Final Rule 82 FR 
3078 (Jan. 10, 2017). The document is available in the following 
docket EPA-HQ-OAR-2015-0531.
---------------------------------------------------------------------------

    Contrary to Texas's own conclusions, the EPA finds that the modeled 
TCEQ control scenarios are projected to achieve meaningful reductions 
in impairment. In table 21, based on Texas's own modeling and 
considering visibility impairment using light extinction units, the 
control scenarios provide for meaningful progress in reducing 
visibility impairment, particularly at Caney Creek. Considering just US 
anthropogenic impairment in 2028, Texas is responsible for 43 percent 
of the total U.S. anthropogenic impairment on the 20 percent most 
impaired days at Caney Creek. The modeled 3.18 Mm-1 reduction in 
impairment under Texas's Scenario 2 represents a 10.6 percent reduction 
of the total US anthropogenic impairment in 2028 and 25 percent 
reduction of the Texas contribution to anthropogenic impairment. In 
consideration of the statutory goal to remedy ``any existing impairment 
of visibility in mandatory Class I Federal area which impairment 
results from manmade air pollution,'' \229\ it is not reasonable to 
dismiss a potential 10.6 percent reduction in the nationwide total 
anthropogenic impairment and a 25 percent reduction in the Texas 
contribution to impairment as insignificant, especially since Texas 
found all of the modeled controls to be below their chosen cost-
effectiveness threshold of $5,000/ton.
---------------------------------------------------------------------------

    \229\ 42 U.S.C. 7491(a)(1) (emphasis added).

[[Page 83367]]



                                                                Table 21 \230\--Visibility Benefit of Texas's Control Scenario 2
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                                                      Scenario 2
                                                                                      Non-               Total                                Scenario 2     Scenario 2               extinction
                                                                  2028      Texas    Texas   Total US   anthro     Texas % of   Scenario 2   reduction of  reduction  of  Scenario 2   reduction
              Class I area                  IMPROVE monitor    extinction   anthro    U.S.    anthro     from       total US    extinction     total US        Texas      extinction   compared
                                                                 (Mm-1)      (%)     anthro   (Mm-1)     Texas   anthropogenic   reduction  anthropogenic  anthropogenic   reduction  to Natural
                                                                                      (%)               (Mm-1)     impairment     (Mm-1)         (%)        contribution     (dv)     conditions
                                                                                                                                                                (%)                      (dv)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Caney Creek............................  CACR1                       55.4       23       31     29.92     12.74            43        -3.18        -10.60         -25.00        -0.56       -1.32
Big Bend...............................  BIBE1                       41.2       10        5      6.18      4.12            67        -0.31         -5.00          -7.50        -0.07       -0.18
Upper Buffalo..........................  UPBU1                       53.4       13       38     27.23      6.94            25         -1.2         -4.40         -17.30        -0.21       -0.48
Wichita Mountains......................  WIMO1                       53.2       18       33     27.13      9.58            35        -1.19         -4.40         -12.40        -0.22       -0.61
Hercules-Glades........................  HEGL1                       57.2        9       48     32.60      5.15            16        -0.78         -2.40         -15.20        -0.13       -0.31
Salt Creek.............................  SACR1                       40.3       12       34     18.54      4.84            26        -0.27         -1.50          -5.60        -0.06       -0.16
Guadalupe Mountains....................  GUMO1                         34       11       11      7.48      3.74            50         -0.1         -1.30          -2.70        -0.03       -0.06
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Texas's consideration of visibility benefit is also unreasonable 
because Texas only considered the potential visibility benefits 
relative to ``dirty background'' conditions. Because estimates of the 
visibility benefits of emission control measures help guide regulatory 
decisions, relying solely on a quantification of visibility benefits 
relative to ``dirty background'' \231\ as Texas did in its 2021 
Regional Haze Plan (i.e., conditions with greater impairment than 
natural background visibility conditions) obscures the full potential 
benefits of control measures and makes it less likely that a measure, 
or measures, would appear reasonable from a visibility benefit 
perspective.\232\ Thus, this approach to considering visibility benefit 
serves to maintain the current impairment at Class I areas, which is 
inconsistent with the statutory goal of the CAA Sec.  169A(a)(1) to 
eliminate future, and remedy existing manmade visibility impairment. 
Texas's own modeling results show that had Texas considered the 
visibility improvement associated with the control scenarios it modeled 
relative to natural background, the visibility improvement would have 
been considerably larger. For example, under control Scenario 2, the 
visibility improvement at Caney Creek would be considerably larger 
(1.32 deciviews) than the values documented by Texas (0.56 
deciview).\233\ The right most column in table 21 shows Texas's modeled 
visibility benefits calculated relative to natural visibility 
conditions. Because Texas's consideration of projected visibility 
benefits was limited to a dirty background basis and did not consider 
the full potential benefits associated with each control scenario it 
evaluated, Texas's determination that the visibility benefits did not 
support requiring any additional control measures was unreasonable.
---------------------------------------------------------------------------

    \230\ See ``EPA TX contributions to Class I areas.xlsx'' 
available in the docket for this action.
    \231\ North Dakota v. EPA, 730 F.3d 750, 764-766 (8th Cir. 2013) 
(``Although the State was free to employ its own visibility model 
and to consider visibility improvement in its reasonable progress 
determinations, it was not free to do so in a manner that was 
inconsistent with the CAA. Because the goal of Sec.  169A is to 
attain natural visibility conditions in mandatory Class I Federal 
areas, see 42 U.S.C. 7491(a)(1), and EPA has demonstrated that the 
visibility model used by the State would serve instead to maintain 
current degraded conditions, we cannot say that EPA acted in a 
manner that was arbitrary, capricious, or an abuse of discretion by 
disapproving the State's reasonable progress determination based 
upon its cumulative source visibility modeling.'').
    \232\ See 2019 Guidance at 16, 36.
    \233\ Because improvement in visibility is a non-linear function 
of light extinction, focusing on visibility improvement in delta 
deciviews can mask the actual progress that can be made in reducing 
impairment by the implementation of controls unless visibility 
improvement is measured against clean background conditions. See the 
TSD in the docket for this action for additional discussion of 
background conditions and visibility modeling.
---------------------------------------------------------------------------

    Recent annual emissions data from EPA's Clean Air Markets Program 
Data also contradict Texas's conclusion that no controls are needed due 
to the lack of perceptible visibility improvement. Across all states, 
Texas EGU SO<INF>2</INF> emissions ranked 1st and has ranked 1st over 
the past several years.\234\ Within the group of sources analyzed by 
Texas, Martin Lake and Coleto Creek ranked 6th and 31st, respectively, 
in facility-wide SO<INF>2</INF> emissions across the United 
States.\235\ The magnitude of SO<INF>2</INF> emissions from the sources 
Texas included in its sensitivity run, as well as all of Texas's EGUs 
statewide, is demonstrated in the model results showing Texas's large 
contribution to the total U.S anthropogenic visibility impairment. 
This, combined with the outcome of the four-factor analyses, emphasize 
that emission reductions from additional SO<INF>2</INF> controls on the 
sources Texas considered are cost-effective would result in meaningful 
progress towards remedying visibility impairment from manmade pollution 
at impacted Class I areas.
---------------------------------------------------------------------------

    \234\ See ``SO<INF>2</INF> annual emissions by state 2016-
2022.xlsx'' spreadsheet available in the docket for this action and 
available on EPA's CAMPD website, https://campd.epa.gov/data/custom-data-download.
    \235\ See ``Texas annual emissions by facility 2022.xlsx'' 
spreadsheet available in the docket for this action, and available 
on EPA's CAMPD website https://campd.epa.gov/data/custom-data-download.
---------------------------------------------------------------------------

    Therefore, the EPA finds that Texas's use of perceptibility as a 
visibility threshold to support its decision to dismiss controls was 
unreasonable, resulted in an unjustified long-term strategy for the 
second planning period, and is inconsistent with the CAA and the RHR.
g. EPA's Conclusions and Proposed Action on Texas's Four Factor 
Analysis
    As explained in the preceding sections, due to numerous flaws in 
its evaluation of the four-factors and the resulting control 
determinations, Texas failed to submit to the EPA a long-term strategy 
that includes ``the enforceable emissions limitations, compliance 
schedules, and other measures that are necessary to make reasonable 
progress'' as required by 40 CFR 51.308(f)(2).\236\ Consequently, the 
EPA is proposing to find that the 2021 Texas Regional Haze Plan does 
not satisfy the requirements of 40 CFR 51.308(f)(2).
---------------------------------------------------------------------------

    \236\ See also CAA 169A(b)(2).
---------------------------------------------------------------------------

3. Additional Long-Term Strategy Requirements
    Aside from the long-term strategy requirements already discussed, 
States must also meet the requirements specified in 40 CFR 
51.308(f)(2)(ii)-(iv) when developing their long-term strategies for 
the second planning period. Under 40 CFR 51.308(f)(2)(ii) states are 
required to consult with other states that have emissions that are

[[Page 83368]]

reasonably anticipated to contribute to visibility impairment in Class 
I areas to develop coordinated emission management strategies. Texas 
included documentation of its consultation with other states and the 
FLMs in appendix A of its 2021 Regional Haze Plan.
    In addition to our analysis on Section 51.308(f)(2)(iii) above, 
this section also requires that the emissions information considered to 
determine the measures that are necessary to make reasonable progress 
include information on emissions for the most recent year for which the 
State has submitted triennial emissions data to the EPA (or a more 
recent year), with a 12-month exemption period for newly submitted 
data. Texas's 2021 Texas Regional Haze Plan included 2011, 2014, and 
2017 statewide NEI emission data for NO<INF>X</INF>, SO<INF>2</INF>, 
PM, VOCs, and NH<INF>3</INF>. For the base case CAMx modeling, Texas 
also relied on 2018 emissions from EPA's AMPD, and 2016 emissions data 
reported to the State of Texas Air Reporting System (STARS) database 
for non-EGU sources.
    Finally, in developing their long-term strategies, States must 
consider five additional factors specified under 40 CFR 
51.308(f)(2)(iv). The five additional factors are: emission reductions 
due to ongoing air pollution control programs, including measures to 
address reasonably attributable visibility impairment; measures to 
mitigate the impacts of construction activities; source retirement and 
replacement schedules; basic smoke management practices for prescribed 
fire used for agricultural and wildland vegetation management purposes 
and smoke management programs; and the anticipated net effect on 
visibility due to projected changes in point, area, and mobile source 
emissions over the period addressed by the long-term strategy. Chapter 
7 of Texas's 2021 Regional Haze Plan includes a description of these 
additional factors.
    Regardless, as explained in preceding sections, due to flaws and 
omissions in its source selection, four-factor analyses, and the 
resulting control determinations, we find that Texas failed to 
reasonably ``evaluate and determine the emission reduction measures 
that are necessary to make reasonable progress'' by considering the 
four statutory factors as required by CAA section 169A(b)(2)(A), CAA 
section 169A(g)(1), and 40 CFR 51.308(f)(2)(i). We also find that Texas 
failed to adequately document the technical basis that it relied upon 
in evaluating potential emissions reduction measures, as required by 40 
CFR 51.308(f)(2)(iii). In so doing, the EPA finds that Texas failed to 
submit to the EPA a long-term strategy that includes ``the enforceable 
emissions limitations, compliance schedules, and other measures that 
are necessary to make reasonable progress'' as required by 40 CFR 
51.308(f)(2). Consequently, the EPA finds that the Texas's 2021 
Regional Haze Plan does not satisfy the long-term strategy requirements 
of 40 CFR 51.308(f)(2). Therefore, we are proposing to disapprove these 
corresponding portions of Texas's SIP submission.

F. Reasonable Progress Goals

    Section 51.308(f)(3) contains the requirements pertaining to RPGs 
for each Class I area. Texas is host to two Class I areas and is 
therefore subject to Sec.  51.308(f)(3)(i) and, if appliable, to (ii). 
Section 51.308(f)(3)(i) requires a State in which a Class I area is 
located to establish RPGs--one each for the most impaired and clearest 
days--reflecting the visibility conditions that will be achieved at the 
end of the implementation period as a result of the emission 
limitations, compliance schedules and other measures required under 
paragraph (f)(2) to be in states' long-term strategies, as well as 
implementation of other CAA requirements. The long-term strategies as 
reflected by the RPGs must provide for an improvement in visibility on 
the most impaired days relative to the baseline period and ensure no 
degradation on the clearest days relative to the baseline period. 
Section 51.308(f)(3)(ii) applies in circumstances in which a Class I 
area's RPG for the most impaired days represents a slower rate of 
visibility improvement than the uniform rate of progress calculated 
under 40 CFR 51.308(f)(1)(vi). Under Sec.  51.308(f)(3)(ii)(A), if the 
State in which a mandatory Class I area is located establishes an RPG 
for the most impaired days that provides for a slower rate of 
visibility improvement than the URP, the State must demonstrate that 
there are no additional emission reduction measures for anthropogenic 
sources or groups of sources in the State that would be reasonable to 
include in its long-term strategy. Section 51.308(f)(3)(ii)(B) requires 
that if a State contains sources that are reasonably anticipated to 
contribute to visibility impairment in a Class I area in another State, 
and the RPG for the most impaired days in that Class I area is above 
the URP, the upwind State must provide the same demonstration.
    Texas established RPGs based on projected visibility improvements 
from emission reductions associated with the Federal CAA, the Texas 
Clean Air Act, Texas' ozone SIP revisions and rules, and agreements 
between the EPA and petrochemical refineries and carbon black 
manufacturing plants for nitrogen oxides (NO<INF>X</INF>) and sulfur 
dioxide (SO<INF>2</INF>) emissions reductions. As part of establishing 
the RPGs, the TCEQ evaluated the impact of emissions reductions from 
these adopted measures on visibility in Class I areas using 
photochemical modeling. Further, the TCEQ evaluated the impacts of 
additional controls beyond those already adopted using photochemical 
modeling in a sensitivity analysis. Based on the results of Texas's 
four-factor analysis and the sensitivity analysis, the TCEQ concluded 
that additional measures for visibility improvement at Texas Class I 
areas and Class I areas affected by Texas emissions are not reasonable 
for this planning period.
    The TCEQ elected to perform CAMx modeling to develop its future 
year visibility projections to establish its reasonable progress goals 
and evaluate the impact of identified emissions reductions on 
visibility in Class I areas. The CAMx modeling was based on the EPA's 
Modeling Guidance and consistent with the modeling protocol included in 
appendix G of its SIP (Modeling Protocol). The photochemical modeling 
used to support the 2021 Texas Regional Haze Plan consisted of base 
case model runs, future year model runs, including source apportionment 
runs, and three sensitivity runs.\237\ The TCEQ describes the 
development of its emission inventories for use in each modeling 
scenario in appendix E of its SIP (Emissions Modeling).
---------------------------------------------------------------------------

    \237\ 2021 Texas Regional Haze Plan at 8-2.
---------------------------------------------------------------------------

    The TCEQ elected to use the adjusted Uniform Rate of Progress (URP) 
in its 2021 Regional Haze Plan SIP to evaluate its reasonable progress 
goals. The TCEQ presents the visibility for Class I areas on the 20% 
clearest days and 20% most impaired days for the 2014-2017 period, 2028 
projected future year, and the 2028 adjusted glidepath and are shown in 
table 8-43 of its SIP and presented here in table 22.

[[Page 83369]]



             Table 22--Visibility for Class I Areas on 20% Most Impaired Days and 20% Clearest Days
----------------------------------------------------------------------------------------------------------------
                                                                      Future year        2028       Future year
                                                     2014-2017 20%     (2028) 20%      adjusted     (2028) 20%
         Class I area (IMPROVE ID, state)            clearest days   clearest days    glidepath    most impaired
                                                         (dv)             (dv)           (dv)        days (dv)
----------------------------------------------------------------------------------------------------------------
Big Bend National Park (N.P.) (BIBE, TX)..........             5.2              4.9         14.4            14.2
Bosque del Apache Wilderness Area (W.A.) (BOAP,                4.6              4.2          9.9             9.6
 NM)..............................................
Breton Island W.A. (BRIS, LA).....................            11.8             11.3         19.8            18.3
Caney Creek W.A. (CACR, AR).......................             8.2              7.8         18.8            17.1
Great Sand Dunes W.A. (GRSA, CO)..................             2.9              2.6          8.2             7.3
Guadalupe Mountains N.P. (GUMO, TX)...............             4.5              4.1         12.8            12.2
Hercules-Glades W.A. (HEGL, MO)...................             9.8              9.1         19.6            17.4
Mingo W.A. (MING, MO).............................            11.2             10.6         20.2            18.6
Rocky Mountain N.P. (ROMO, CO)....................             1.3              1.1          9.2             7.3
Salt Creek W.A. (SACR, NM)........................             6.7              6.2         13.5            13.9
Upper Buffalo W.A. (UPBU, AR).....................             8.4              7.9         19.2            16.7
White Mountain W.A. (WHIT, NM)....................             2.6              2.2           10             9.5
Wheeler Peak W.A. (WHPE, NM)......................             0.3              0.1          6.5             5.3
Wichita Mountains W.A. (WIMO, OK).................             8.4              7.7         17.4            16.7
----------------------------------------------------------------------------------------------------------------
Source: Texas 2021 Regional Haze SIP, Table 8-43.

    Texas included baseline haze indices for Big Bend and Guadalupe 
Mountains in Chapter 8 of its 2021 Regional Haze Plan. Baseline 
visibility for the Big Bend Class I area is 5.78 dv for the 20% 
clearest days and 15.57 dv for the 20% most impaired days. Baseline 
visibility for the Guadalupe Mountains Class I area is 5.92 dv for the 
20% clearest days and 14.60 dv for the 20% most impaired days. As Texas 
notes in its 2021 Texas Regional Haze Plan, and as shown in the data 
presented in table 22, the RPGs Texas established for both Big Bend and 
Guadalupe Mountains are below the adjusted glidepath.
    Texas emissions impact visibility at one Class I area, Salt Creek 
Wilderness Area, in New Mexico, that is projected to be above the 
glidepath. Section 51.308(f)(3)(ii) requires states to demonstrate for 
Class I areas with a 2028 reasonable progress goal for the 20% most 
impaired days above the 2028 URP that there are no additional emission 
reduction measures for sources in the State that would be reasonable to 
include in the long-term strategy. The TCEQ states in its 2021 Texas 
Regional Haze Plan that the New Mexico Environment Department had not 
yet established a reasonable progress goal for Salt Creek Wilderness 
Area or developed its long-term strategy at the time Texas prepared its 
SIP; however Texas states that its analysis in the long-term strategy 
is robust, in accordance with 40 CFR 51.308(f)(3)(ii), and that it has 
provided a thorough evaluation of the Texas sources that impact Class I 
areas in and around Texas and consideration of whether any additional 
emission reduction measures are reasonable for the second planning 
period.\238\
---------------------------------------------------------------------------

    \238\ 2021 Texas Regional Haze Plan at 8-59 to 8-60.
---------------------------------------------------------------------------

    As previously discussed in Section IV.E.1, using its source 
selection methodology, Texas did not select any sources of 
SO<INF>2</INF> for further evaluation at Salt Creek, despite Texas's 
PSAT modeling showing that Texas sources are responsible for almost 
three times the amount of influence due to particulate sulfate and more 
than one and half times the influence due to particulate nitrate as the 
home State of New Mexico.\239\ Focusing on modeled U.S. anthropogenic 
impacts alone, Texas anthropogenic sources account for approximately 
51.3% of the particulate sulfate concentrations at Salt Creek, with 
more than half of the Texas anthropogenic contribution coming from 
Texas EGUs.\240\ Furthermore, the sensitivity modeling Texas conducted 
showed that potential SO<INF>2</INF> and NO<INF>X</INF> reductions from 
the aggregate group of control measures considered would provide for an 
estimated 0.07 dv improvement in visibility at Salt Creek. This is 
despite the fact that only a few of the NO<INF>X</INF> sources included 
in the sensitivity analyses were included based on their impact to Salt 
Creek and no SO<INF>2</INF> sources were selected based on their impact 
at Salt Creek. The 0.07 dv improvement is calculated from a reduction 
in extinction of 0.27 Mm<SUP>-1</SUP> and represents a 1.5 percent 
reduction of total U.S. anthropogenic contribution and a 5.6 percent 
reduction of Texas's total anthropogenic contribution to visibility 
impairment at Salt Creek. While New Mexico had not established an RPG 
for Salt Creek at the time Texas submitted its SIP, contrary to its 
assertion, Texas's analysis did not meet the requirements of 
51.308(f)(3)(ii)(B) to conduct a robust analysis with respect to Salt 
Creek as evidenced by the fact Texas did not evaluate sources of 
SO<INF>2</INF> despite PSAT modeling showing the substantial impact on 
the area from Texas.
---------------------------------------------------------------------------

    \239\ 2021 Texas Regional Haze Plan at 8-52 and table 8-41 at 8-
53.
    \240\ See 2021 Texas Regional Haze Plan, appendix F at F-63.
---------------------------------------------------------------------------

    Under 40 CFR 51.308(f)(3)(iv), the EPA must evaluate the 
demonstrations the State developed pursuant to 40 CFR 51.308(f)(2) to 
determine whether the State's reasonable progress goals for visibility 
improvement provide for reasonable progress towards natural visibility 
conditions. As previously explained in section IV.E., we are proposing 
to disapprove Texas's long-term strategy for failing to meet the 
requirements of 40 CFR 51.308(f)(2). Therefore, we also propose to 
disapprove Texas's reasonable progress goals under 40 CFR 51.308(f)(3) 
because compliance with that requirement is dependent on compliance 
with 40 CFR 51.308(f)(2).

G. Reasonably Attributable Visibility Impairment (RAVI)

    The RHR contains a requirement at Sec.  51.308(f)(4) related to any 
additional monitoring that may be needed to address visibility 
impairment in Class I areas from a single source or a small group of 
sources. This is called ``reasonably attributable visibility 
impairment,'' \241\ also known as RAVI.

[[Page 83370]]

Under this provision, if the EPA or the FLM of an affected Class I area 
has advised a State that additional monitoring is needed to assess 
RAVI, the State must include in its SIP revision for the second 
implementation period an appropriate strategy for evaluating such 
impairment. The EPA has not advised Texas to that effect, and the FLMs 
for the Class I areas that Texas contributes to have not identified any 
RAVI from Texas sources.\242\ For this reason, the EPA proposes to 
approve the portions of Texas's 2021 Regional Haze Plan relating to 40 
CFR 51.308(f)(4).
---------------------------------------------------------------------------

    \241\ The EPA's visibility protection regulations define 
``reasonably attributable visibility impairment'' as ``visibility 
impairment that is caused by the emission of air pollutants from 
one, or a small number of sources.'' 40 CFR 51.301.
    \242\ 2021 Texas Regional Haze Plan at 7-17.
---------------------------------------------------------------------------

H. Monitoring Strategy and Other Implementation Plan Requirements

    Section 51.308(f)(6) specifies that each comprehensive revision of 
a state's regional haze SIP must contain or provide for certain 
elements, including monitoring strategies, emissions inventories, and 
any reporting, recordkeeping and other measures needed to assess and 
report on visibility. A main requirement of this subsection is for 
states with Class I areas to submit monitoring strategies for 
measuring, characterizing, and reporting on visibility impairment. 
Compliance with this requirement may be met through participation in 
the Interagency Monitoring of Protected Visual Environments (IMPROVE) 
network.
    Texas discusses its monitoring strategy in Chapter 5 of its 2021 
Regional Haze Plan. Haze species in Texas are measured and analyzed via 
the Interagency Monitoring of Protected Visual Environments (IMPROVE) 
network.\243\ Table 23 of this preamble lists the IMPROVE stations 
representing visibility at Texas Class I areas. Due to the close 
proximity of the Class I areas, Carlsbad Caverns (New Mexico) and 
Guadalupe Mountains (Texas) share the same IMPROVE monitor.
---------------------------------------------------------------------------

    \243\ See 2021 Texas Regional Haze Plan, Chapter 5 for more 
information about Texas's monitoring strategy.

                          Table 23--IMPROVE Stations at Federal Class I Areas in Texas
----------------------------------------------------------------------------------------------------------------
             Monitor ID                   Class I area               Sponsor                Years operated
----------------------------------------------------------------------------------------------------------------
BIBE1..............................  Big Bend National Park  National Parks Service  1988-Present.
GUMO1..............................  Guadalupe Mountains     National Parks Service  1988-Present.
                                      National Park.
----------------------------------------------------------------------------------------------------------------

    Section 51.308(f)(6)(i) requires SIPs to provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess whether reasonable progress goals to address regional haze for 
all mandatory Class I Federal areas within the State are being 
achieved.
    The IMPROVE program reviewed its aerosol monitoring sites in 2006 
to set priorities for maintaining the sites in the event of federal 
budget cuts affecting the IMPROVE program.\244\ This review determined 
that the IMPROVE aerosol samplers at Texas's two Class I areas 
represent conditions different from the conditions at the nearest Class 
I area IMPROVE monitors. Texas's two Class I IMPROVE monitors are not 
candidates for discontinuation since other IMPROVE monitors cannot 
represent conditions at Big Bend or Guadalupe Mountains.
---------------------------------------------------------------------------

    \244\ Spatial and Seasonal Patterns and Temporal Variability of 
Haze and its Constituents in the United States Report IV: November 
2006 available at https://vista.cira.colostate.edu/Improve/spatial-and-seasonal-patterns-and-temporal-variability-of-haze-and-its-constituents-in-the-united-states-report-iv-november-2006/.
---------------------------------------------------------------------------

    Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by 
which monitoring data and other information are used in determining the 
contribution of emissions from within the State to regional haze 
visibility impairment at mandatory Class I Federal areas both within 
and outside the State. In its 2021 Texas Regional Haze Plan, Texas 
stated that future assessments of visibility impairment and progress in 
reducing visibility impairment at Texas's two Class I areas, and at 
Class I areas in other states that Texas's emissions may potentially 
affect, will use the revised IMPROVE algorithm and will use data as 
prescribed in the EPA's Regional Haze Rule (40 CFR part 51, subpart P--
Visibility Protection). The assessment will follow, as appropriate, the 
EPA's guidance including the 2019 Guidance and the 2018 Visibility 
Tracking Guidance.
    Section 51.308(f)(6)(iii) does not apply to Texas, as it has a 
Class I area.
    Section 51.308(f)(6)(iv) requires the SIP to provide for the 
reporting of all visibility monitoring data to the Administrator at 
least annually for each Class I area in the State. As noted above, the 
monitoring strategy for Texas relies upon the continued availability of 
the IMPROVE network. The TCEQ does not directly collect or handle 
IMPROVE data. The TCEQ will continue to participate in the IMPROVE 
Visibility Information Exchange Web System (VIEWS). The TCEQ considers 
VIEWS to be a core part of the overall IMPROVE program. The TCEQ will 
report IMPROVE data from the two Class I areas in Texas to the EPA 
using the VIEWS web system.
    If Texas collects any visibility monitoring data through the 
state's air quality monitoring networks, the TCEQ will report those 
data to the EPA as specified under the Performance Partnership Grant 
agreement negotiated with the EPA Region 6. All validated data and data 
analysis results from any TCEQ visibility-related special studies are 
public information. The TCEQ will continue its practice of sharing the 
data and information with the EPA. Texas supports the continued 
operation of the IMPROVE network through both State and Federal funding 
mechanisms.
    Section 51.308(f)(6)(v) requires SIPs to provide for a statewide 
inventory of emissions of pollutants that are reasonably anticipated to 
cause or contribute to visibility impairment, including emissions for 
the most recent year for which data are available and estimates of 
future projected emissions. It also requires a commitment to update the 
inventory periodically. Texas provides for emissions inventories and 
estimates for future projected emissions by participating in the 
CenSARA RPO and complying with the EPA's Air Emissions Reporting Rule 
(AERR). In 40 CFR part 51, subpart A, the AERR requires states to 
submit updated emissions inventories for criteria pollutants to the 
EPA's Emissions Inventory System (EIS) every three years. The emission 
inventory data is used to develop the NEI, which provides for, among 
other things, a triennial state-wide inventory of pollutants that are 
reasonably anticipated to cause or contribute to visibility impairment.
    Chapter 6 of the 2021 Texas Regional Haze Plan includes a 
discussion of the NEI data, and Section 8.3 details specific emission 
inventories and emissions inputs developed for the regional haze 
photochemical modeling

[[Page 83371]]

conducted by the TCEQ. The source categories of the emissions 
inventories included are: (1) point sources, (2) area sources, (3) non-
road mobile sources, (4) drilling rigs, (5) commercial marine vessels 
and locomotives, (6) airports and (7) on-road mobile sources. Statewide 
pollutant summaries by source category for the years 2011, 2014, and 
2017 are provided in tables 6-1, 6-2, and 6-3 of Texas 2021 Regional 
Haze Plan. Summaries are for the following pollutants: SO<INF>2</INF>, 
NO<INF>X</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, VOCs, CO, and 
NH<INF>3</INF>. Texas also provided a summary of anthropogenic 
SO<INF>2</INF> and NO<INF>X</INF> emissions for each source type for 
2011, 2014, and 2017 and are presented in tables 6-4 and 6-5 of the 
2021 Texas Regional Haze Plan.
    Section 51.308(f)(6)(v) also requires states to include estimates 
of future projected emissions and include a commitment to update the 
inventory periodically. Texas estimated 2028 future year emissions by 
applying growth projections and accounting for known existing federal, 
State, and local controls. The development of Texas's 2028 modeling 
emissions for the 2021 Texas Regional Haze Plan includes some methods 
used in previous SIP modeling for ozone, such as the Federal Tier 3 
Vehicle Emission and Fuel Standards program, the Mass Emissions Cap-
and-Trade (MECT) Program in the Houston-Galveston-Brazoria area, the 
Highly Reactive VOC Emission Cap-and-Trade (HECT) Program in Harris 
County, the Midlothian Cement Kiln caps and related agreed orders in 
the Dallas-Fort Worth area, and the EPA's final Cross-State Air 
Pollution Rule (CSAPR) update. Summaries of the primary data sources 
for the development of the future case modeling emissions are provided 
in the 2021 Texas Regional Haze Plan, appendix E, table 1-4: Summary of 
Future Case Point Source Emission Data Sources, table 1-5: Summary of 
Future Case On-Road Mobile Source Emission Data Sources, and table 1-6: 
Summary of Future Case Non-Road Mobile, Off-Road, Area, Oil-and-Gas, 
and Biogenic Source Emission Data Sources. The gridded photochemical 
modeling input files for the 2016 and 2028 emissions were provided 
along with the full emission processing message log files during 
Texas's public comment period. For point sources, Texas evaluated large 
stationary sources of emissions, such as electric generating units 
(EGUs), smelters, industrial boilers, petroleum refineries, and 
manufacturing facilities. Point source emissions were developed for the 
January 1 through December 31, 2016, annual episode with a 2028 future 
year projection. The data sources for development of the point source 
modeling emissions are summarized in the 2021 Texas Regional Haze Plan, 
appendix E, table 2-1: Sources of Point Source Emissions Data.
    The EPA proposes to find that Texas has met the requirements of 40 
CFR 51.308(f)(6) as described above, including its continued 
participation in the IMPROVE network and the CenSARA RPO and its on-
going compliance with the AERR, and that no further elements are 
necessary at this time for Texas to assess and report on visibility 
pursuant to 40 CFR 51.308(f)(6)(vi).
    In sum, for all the reasons discussed in this section, the EPA is 
proposing to approve Texas's 2021 Regional Haze Plan as meeting the 
requirements of 40 CFR 51.308(f)(6).

I. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires that periodic comprehensive revisions 
of states' regional haze plans also address the progress report 
requirements of 40 CFR 51.308(g)(1) through (5). The purpose of these 
requirements is to evaluate progress towards the applicable RPGs for 
each Class I area within the State and each Class I area outside the 
State that may be affected by emissions from within that State. 
Sections 51.308(g)(1) and (2) apply to all states and require a 
description of the status of implementation of all measures included in 
a state's first implementation period regional haze plan and a summary 
of the emission reductions achieved through implementation of those 
measures. Section 51.308(g)(3) applies only to states with Class I 
areas within their borders and requires such states to assess current 
visibility conditions, changes in visibility relative to baseline 
(2000-2004) visibility conditions, and changes in visibility conditions 
relative to the period addressed in the first implementation period 
progress report. Section 51.308(g)(4) applies to all states and 
requires an analysis tracking changes in emissions of pollutants 
contributing to visibility impairment from all sources and sectors 
since the period addressed by the first implementation period progress 
report. This provision further specifies the year or years through 
which the analysis must extend depending on the type of source and the 
platform through which its emission information is reported. Finally, 
Sec.  51.308(g)(5), which also applies to all states, requires an 
assessment of any significant changes in anthropogenic emissions within 
or outside the State have occurred since the period addressed by the 
first implementation period progress report, including whether such 
changes were anticipated and whether they have limited or impeded 
expected progress towards reducing emissions and improving visibility.
    The 2021 Texas Regional Haze Plan describes the status of measures 
of the long-term strategy from the first implementation period to 
address the requirements found in 40 CFR 51.308(g)(1) and (2). Control 
measures to reduce emission within and outside the State are found in 
the 2021 Texas Regional Haze Plan, Chapter 7: Long-Term Strategy to 
Establish Reasonable Progress Goals, Section 7.4: Federal Programs that 
Reduce Stationary Source Emissions, Section 7.5: Federal Programs that 
Reduce Mobile Source Emissions, and Section 7.6: State Air Pollution 
Control Programs. Control measures in the State are included in Section 
7.6: State Air Pollution Control Programs, which discusses both State 
stationary and mobile source emissions control measures; Section 7.6.2: 
Best Available Control Technology (BACT) Requirements, which discusses 
air permitting requirements for new and modified sources of air 
pollution; and finally Section 7.6.3: Additional Measures, which 
discusses other measures addressing air pollution from mobile sources, 
construction activities, and fires, and measures addressing energy 
efficiency. Emissions reductions are found in the 2021 Texas Regional 
Haze Plan, Chapter 6: Emissions Inventory, Section 6.8: NO<INF>X</INF> 
and SO<INF>2</INF> Emissions Trends, table 6-4: Anthropogenic 
NO<INF>X</INF> Emissions by Source Type, and table 6-5: Anthropogenic 
SO<INF>2</INF> Emissions by Source Type.
    The EPA proposes to find that Texas has addressed the requirements 
of 40 CFR 51.308(g)(1) and (2) because the 2021 Texas Regional Haze 
Plan describes the measures included in the long-term strategy from the 
first implementation period, as well as the status of their 
implementation and the emission reductions achieved through such 
implementation.
    Section 51.308(g)(3) requires that for each Class I area within the 
State, the State must assess the following visibility conditions and 
changes, with values for most impaired, least impaired and/or clearest 
days as applicable expressed in terms of five-year averages of these 
annual values. The 2021 Texas Regional Haze Plan includes summaries of 
visibility conditions in Chapter 4: Assessment of Baseline and Current

[[Page 83372]]

Conditions and Estimate of Natural Conditions in Class I Areas, Section 
4.2: Baseline Visibility Conditions, Section 4.3: Natural Visibility 
Conditions. Changes in visibility conditions are displayed in Chapter 
8: Reasonable Progress Goals, Section 8.4: Reasonable Progress Goal 
Status. The EPA therefore proposes to find that Texas has addressed the 
requirements of 40 CFR 51.308(g)(3).
    Pursuant to Sec.  51.308(g)(4), Texas evaluated emission trends for 
reasonable progress for the 2021 Texas Regional Haze Plan and presented 
those data in Chapter 6: Emissions Inventory, Section 6.7: Emissions 
Summaries, table 6-1: 2011 Statewide Pollutant Summary by Source 
Category, table 6-2: 2014 Statewide Pollutant Summary by Source 
Category, table 6-3: 2017 Statewide Pollutant Summary by Source 
Category, table 6-4: Anthropogenic NO<INF>X</INF> Emissions by Source 
Type, table 6-5: Anthropogenic SO<INF>2</INF> Emissions by Source Type. 
The EPA is proposing to find that Texas has addressed the requirements 
of Sec.  51.308(g)(4) by providing emissions information for 
NO<INF>X</INF>, SO<INF>2</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, 
VOCs, and NH<INF>3</INF> broken down by type of source.
    Since the 2009 and 2014 Texas regional haze SIP revisions, 
reductions in anthropogenic emissions within and outside the State have 
occurred from the following: (1) ongoing rules and regulations for 
nonattainment areas in Texas (see the 2021 Texas Regional Haze Plan 
Chapter 7: Long-Term Strategy to Establish Reasonable Progress Goals, 
Section 7.6: State Air Pollution Control Programs); (2) closing several 
major coal-fired plants in Texas, which have permanently reduced 
emissions (see Chapter 7, Section 7.6.3.8: Potential Effects of 
Economically Driven Coal Burning Power Plant Closures); (3) continuing 
reductions in mobile emissions through the incentives like Texas 
Emissions Reduction Plan (TERP) (see Chapter 7, Section 7.6.3.1: Texas 
Emissions Reduction Plan); (4) ongoing energy efficiency state-wide, 
which has continued to increase (see Chapter 7, Section 7.6.3.3: 
Energy-Efficiency (EE) Programs and Renewable Energy (RE) Measures); 
and other items discussed in Chapter 7 of the 2021 Texas Regional Haze 
Plan. Texas uses the emissions trend data in the 2021 Texas Regional 
Haze Plan \245\ to support the assessment that anthropogenic haze-
causing pollutant emissions in Texas have decreased during the 
reporting period and that changes in emissions have not limited or 
impeded progress in reducing pollutant emissions and improving 
visibility. Texas's 2017 emission inventories for NO<INF>X</INF>, 
SO<INF>2</INF>, PM<INF>10</INF>, PM<INF>2.5</INF>, VOCs, and 
NH<INF>3</INF> were lower than their 2014 emission inventories for 
those same pollutants emissions.\246\ The EPA is proposing to find that 
Texas has addressed the requirements of Sec.  51.308(g)(5).
---------------------------------------------------------------------------

    \245\ See 2021 Texas Regional Haze Plan, Section 6.8.
    \246\ Trends in anthropogenic NO<INF>X</INF> and SO<INF>2</INF> 
emissions are presented in Figures 6-1 and 6-2 of the 2021 Texas 
Regional Haze Plan, respectively.
---------------------------------------------------------------------------

    In sum, because Texas's 2021 Regional Haze Plan addresses the 
requirements of 40 CFR 51.308(g)(1) through (5) as required by 40 CFR 
51.308(f)(5), the EPA is proposing to approve Texas's 2021 Texas 
Regional Haze Plan as meeting the requirements of 40 CFR 51.308(f)(5) 
for periodic progress reports.

J. Requirements for State and Federal Land Manager Coordination

    Section 169A(d) of the Clean Air Act requires states to consult 
with FLMs before holding the public hearing on a proposed regional haze 
SIP, and to include a summary of the FLMs' conclusions and 
recommendations in the notice to the public. In addition, section 
51.308(i)(2)'s FLM consultation provision requires a State to provide 
FLMs with an opportunity for consultation that is early enough in the 
state's policy analyses of its emission reduction obligation so that 
information and recommendations provided by the FLMs' can meaningfully 
inform the state's decisions on its long-term strategy. If the 
consultation has taken place at least 120 days before a public hearing 
or public comment period, the opportunity for consultation will be 
deemed early enough, Regardless, the opportunity for consultation must 
be provided at least sixty days before a public hearing or public 
comment period at the State level. Section 51.308(i)(2) also provides 
two substantive topics on which FLMs must be provided an opportunity to 
discuss with states: assessment of visibility impairment in any Class I 
area and recommendations on the development and implementation of 
strategies to address visibility impairment. Section 51.308(i)(3) 
requires states, in developing their implementation plans, to include a 
description of how they addressed FLMs' comments.
    The TCEQ consulted with the FLMs about the impact of Texas's 
emissions on regional haze at the regional Class I areas through 
conference calls. The TCEQ gave a presentation in March 2020 and 
discussed impacts to Class I areas in the region. An additional meeting 
was held October 8, 2020, where NPS presented its evaluation of the 
Texas SIP. NPS requested Texas look at 15 additional sources that were 
not included in the TCEQ's four-factor analysis. NPS also requested the 
TCEQ consider impacts to three New Mexico Class I areas: Bandelier, 
Salt Creek, and Carlsbad Caverns. NPS also identified inconsistencies 
between the TCEQ's SIP and the CAA. Both the NPS and FS submitted 
comment letters during the TCEQ's public comment period.
    Texas responded to the FLM comments and included the responses in 
appendix A of their 2021 Regional Haze Plan. Notices of the proposed 
SIP, availability and the public hearing were published on TCEQ's 
website and in the Texas Register, the Fort Worth Star Telegram, the 
Houston Chronicle, the Austin American-Statesman, and the El Paso 
Times. A virtual public hearing on the proposed SIP revision was held 
on December 8, 2020, and was available for participation via internet 
or phone. Written comments relevant to the proposal were accepted until 
the close of business January 8, 2021.
    Additionally, Texas's 2021 Regional Haze Plan includes a commitment 
to revise and submit a regional haze SIP by July 31, 2028, and every 
ten years thereafter. The state's commitment includes submitting 
periodic progress reports in accordance with 40 CFR 51.308(f) and a 
commitment to evaluate progress towards the reasonable progress goal 
for each mandatory Class I Federal area located within the State and in 
each mandatory Class I Federal area located outside the State that may 
be affected by emissions from within the State in accordance with Sec.  
51.308(g).
    Regardless of the consultation described above, compliance with 40 
CFR 51.308(i) is dependent on compliance with 40 CFR 51.308(f)(2)'s 
long-term strategy provisions and (f)(3)'s reasonable progress goals 
provisions. Therefore, because the EPA is proposing to disapprove 
Texas's long-term strategy under 51.308(f)(2) and the reasonable 
progress goals under 51.308(f)(3), the EPA is also proposing to 
disapprove the State's FLM consultation under 51.308(i). While Texas 
did take administrative steps to provide the FLMs the opportunity to 
review and provide feedback on the State's draft regional haze plan, 
the EPA cannot approve that consultation because it was based on a plan 
that does not meet the statutory and regulatory requirements of the CAA 
and the RHR, as described in this notice of proposed rulemaking. In 
addition, if the EPA finalizes our proposed partial approval and 
partial

[[Page 83373]]

disapproval of the 2021 Texas Regional Haze Plan, the State (or the EPA 
in the case of a FIP) will be required to again complete the FLM 
consultation requirements under 40 CFR 51.308(i). Therefore, the EPA 
proposes to disapprove the FLM consultation component of the 2021 Texas 
Regional Haze Plan.

V. Proposed Action

    For the reasons discussed in this notice, under CAA section 
110(k)(3), the EPA is proposing approval of the portions of Texas's 
2021 Regional Haze Plan relating to 40 CFR 51.308(f)(1): calculations 
of baseline, current, and natural visibility conditions, progress to 
date, and the uniform rate of progress; 40 CFR 51.308(f)(4): reasonably 
attributable visibility impairment; 40 CFR 51.308(f)(5): \247\ progress 
report requirements; and 40 CFR 51.308(f)(6): monitoring strategy and 
other implementation plan requirements. The EPA is proposing 
disapproval of the remainder of Texas's 2021 Regional Haze Plan, which 
addresses 40 CFR 51.308(f)(2): long-term strategy; 40 CFR 51.308 
(f)(3): reasonable progress goals; and 40 CFR 51.308(i): FLM 
consultation.
---------------------------------------------------------------------------

    \247\ 40 CFR 51.308(f)(5) requires that the second planning 
period SIP revision address the requirements listed in (g)(1) 
through (g)(5).
---------------------------------------------------------------------------

VI. Environmental Justice Considerations

    Information on Executive Order 12898 (Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations, 59 FR 7629, February 16, 1994) and how EPA defines 
environmental justice (EJ) can be found in the section, below, titled 
``VII. Statutory and Executive Order Reviews.'' For informational and 
transparency purposes only, the EPA is including additional analysis of 
environmental justice associated with this proposed action.
    EPA conducted screening analyses using EJSCREEN, an environmental 
justice mapping and screening tool that provides EPA with a nationally 
consistent dataset and approach for combining various environmental and 
demographic indicators.\248\ The EJSCREEN tool presents these 
indicators at a Census block group (CBG) level or a larger user-
specified ``buffer'' area that covers multiple CBGs.\249\ An individual 
CBG is a cluster of contiguous blocks within the same census tract and 
generally contains between 600 and 3,000 people. EJSCREEN is not a tool 
for performing in-depth risk analysis, but is instead a screening tool 
that provides an initial representation of indicators related to 
environmental justice and is subject to uncertainty in some underlying 
data (e.g., some environmental indicators are based on monitoring data 
which are not uniformly available; others are based on self-reported 
data).\250\ To help mitigate this uncertainty, we have summarized 
EJSCREEN data within larger ``buffer'' areas covering multiple block 
groups and representing the average resident within the buffer areas 
surrounding the sources. We present EJSCREEN environmental indicators 
to help screen for locations where residents may experience a higher 
overall pollution burden than would be expected for a block group with 
the same total population. These indicators of overall pollution burden 
include estimates of ambient particulate matter (PM<INF>2.5</INF>), 
ozone, nitrogen dioxide, and diesel particulate matter concentration, a 
score for traffic proximity and volume, percentage of pre-1960 housing 
units (lead paint indicator), and scores for proximity to Superfund 
sites, risk management plan (RMP) sites, and hazardous waste 
facilities.\251\ EJSCREEN also provides information on demographic 
indicators, including percent low-income, unemployment, communities of 
color, linguistic isolation, and education.
---------------------------------------------------------------------------

    \248\ The EJSCREEN tool is available at https://www.epa.gov/ejscreen.
    \249\ See U.S. Census Bureau Glossary available at https://www.census.gov/programs-surveys/geography/about/glossary.html.
    \250\ In addition, EJSCREEN relies on the five-year block group 
estimates from the U.S. Census American Community Survey. The 
advantage of using five-year over single-year estimates is increased 
statistical reliability of the data (i.e., lower sampling error), 
particularly for small geographic areas and population groups. More 
information is available at https://www.census.gov/content/dam/Census/library/publications/2020/acs/acs_general_handbook_2020.pdf.
    \251\ See EJSCREEN Environmental Justice Mapping and Screening 
Tool: EJSCREEN Technical Documentation for additional information on 
the data and methods used to create the indicators and indexes in 
EJSCREEN, which is available at https://www.epa.gov/ejscreen/technical-information-and-data-downloads.
---------------------------------------------------------------------------

    The EPA prepared EJSCREEN reports covering a buffer area of 
approximately 6-mile radius around each source identified in this 
proposed rulemaking. Table 24 presents a summary of results from the 
EPA's screening-level analysis for a few of the areas in Texas compared 
to the U.S. as a whole. The full, detailed EJSCREEN report for all 
areas is provided in the docket for this rulemaking.

                                 Table 24--EJSCREEN Analysis Summary for Sources
                                 [see detailed EJSCREEN report for all sources]
----------------------------------------------------------------------------------------------------------------
                                     Values for buffer areas (radius) for each source and the U.S. (percentile
                                                           within U.S. where indicated)
            Variables            -------------------------------------------------------------------------------
                                     Limestone      Martin Lake      Oklaunion      San Miguel         U.S.
----------------------------------------------------------------------------------------------------------------
Pollution Burden Indicators:
    Particulate matter (PM2.5),      8.13 [mu]g/  8.8 [mu]g/m\3\     6.94 [mu]g/     8.38 [mu]g/     8.45 [mu]g/
     annual average.............            m\3\        (69%ile)            m\3\            m\3\            m\3\
                                        (49%ile)                        (17%ile)        (58%ile)            (--)
    Ozone, annual average of the          61 ppb        56.9 ppb        57.2 ppb        61.7 ppb        61.8 ppb
     top ten 8-hour daily               (53%ile)        (32%ile)        (33%ile)        (56%ile)            (--)
     maximums...................
    Nitrogen dioxide, annual             3.7 ppb         3.2 ppb         3.6 ppb         2.9 ppb         7.8 ppb
     average....................        (11%ile)         (8%ile)        (11%ile)         (6%ile)            (--)
    Diesel particulate matter...   0.0574 [mu]g/   0.0572 [mu]g/   0.0496 [mu]g/   0.0384 [mu]g/    0.191 [mu]g/
                                            m\3\            m\3\            m\3\            m\3\            m\3\
                                        (11%ile)        (11%ile)         (8%ile)         (4%ile)            (--)
    Toxic releases to air score              320            9400              32              92           4,600
     *..........................        (39%ile)        (92%ile)        (14%ile)        (23%ile)            (--)
    Traffic proximity and volume          12,000           9,900          59,000          28,000       1,700,000
     score *....................         (5%ile)         (4%ile)        (13%ile)         (8%ile)            (--)
    Lead paint (percentage pre-           0.061%           0.12%           0.51%           0.08%            0.3%
     1960 housing)..............        (29%ile)        (38%ile)        (74%ile)        (32%ile)            (--)
    Superfund proximity score *.               0           0.014               0               0            0.39
                                         (0%ile)        (56%ile)         (0%ile)         (0%ile)            (--)
    RMP proximity score *.......            0.14            0.18            0.32           0.084            0.57
                                        (39%ile)        (42%ile)        (53%ile)        (30%ile)            (--)

[[Page 83374]]

 
    Hazardous waste proximity              0.058           0.055               0               0             3.5
     score *....................        (15%ile)        (15%ile)         (0%ile)         (0%ile)            (--)
    Underground storage tank               0.022            0.18            0.11        0.000039             3.6
     proximity score *..........        (29%ile)        (36%ile)        (34%ile)        (26%ile)            (--)
    Wastewater discharge score *              52              50            0.35              14         700,000
                                        (50%ile)        (49%ile)        (18%ile)        (38%ile)            (--)
    Drinking water                           2.7             9.9             2.2            0.86             2.2
     noncompliance, points......        (87%ile)        (92%ile)        (87%ile)        (77%ile)            (--)
Demographic Indicators:
    People of color population..             21%             33%             43%             44%             40%
                                        (37%ile)        (51%ile)        (60%ile)        (61%ile)            (--)
    Low-income population.......             33%             28%             41%             15%             30%
                                        (60%ile)        (52%ile)        (72%ile)        (29%ile)            (--)
    Unemployment rate...........              3%              4%              5%              9%              6%
                                        (45%ile)        (55%ile)        (62%ile)        (79%ile)            (--)
    Linguistically isolated                   1%              0%              4%              0%              5%
     population.................        (59%ile)        (56%ile)        (71%ile)        (57%ile)            (--)
    Population with less than                11%              8%             30%             29%             11%
     high school education......        (60%ile)        (50%ile)        (91%ile)        (91%ile)            (--)
    Population under 5 years of               4%              9%              5%              0%              5%
     age........................        (47%ile)        (80%ile)        (54%ile)        (13%ile)            (--)
    Population over 64 years of              27%             17%             17%             35%             18%
     age........................        (83%ile)        (53%ile)        (55%ile)        (92%ile)            (--)
----------------------------------------------------------------------------------------------------------------
* The traffic proximity and volume indicator is a score calculated by daily traffic count divided by distance in
  meters to the road. The Superfund proximity, RMP proximity, and hazardous waste proximity indicators are all
  scores calculated by site or facility counts divided by distance in kilometers. The underground storage tank
  proximity indicator is the weighted count within a 1,500-foot block group. The toxic releases to air indicator
  is the modeled toxicity-weighted concentration. The wastewater discharge indicator is the modeled toxicity-
  weighted concentrations divided by distance in meters.

    Exposure to PM and SO<INF>2</INF> is associated with significant 
public health effects. Short-term exposures to SO<INF>2</INF> can harm 
the human respiratory system and make breathing difficult. People with 
asthma, particularly children, are sensitive to these effects of 
SO<INF>2</INF>.\252\ Exposure to PM can affect both the lungs and heart 
and is associated with: premature death in people with heart or lung 
disease, nonfatal heart attacks, irregular heartbeat, aggravated 
asthma, decreased lung function, and increased respiratory symptoms, 
such as irritation of the airways, coughing or difficulty breathing. 
People with heart or lung diseases or conditions, children, and older 
adults are the most likely to be affected by PM exposure.\253\ This 
action, which proposes to partially approve and partially disapprove 
the Texas Regional Haze SIP submitted on July 20, 2021, will not 
directly result in a change to emissions or air quality if finalized. 
Further, there is no information in the record indicating that this 
proposed action, if finalized, would have disproportionately high or 
adverse human health or environmental effects on communities with 
environmental justice concerns.
---------------------------------------------------------------------------

    \252\ See Sulfer Dioxide Basics available at https://www.epa.gov/SO<INF>2</INF>-pollution/sulfurdioxide-basics#effect.
    \253\ See Health and Environmental Effects: Particulate Matter 
available at https://www.epa.gov/pm-pollution/healthand-environmental-effects-particulate-matter-pm.
---------------------------------------------------------------------------

VII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve State choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to partially approve and partially disapprove 
State law as meeting or not meeting Federal requirements and does not 
impose additional requirements beyond those imposed by State law.
    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review, Executive 
Order 13563: Improving Regulation and Regulatory Review, and Executive 
Order 14094: Modernizing Regulatory Review

    This action is not a significant regulatory action as defined in 
Executive Order 12866 (58 FR 51735, October 4, 1993), as amended by 
Executive Order 14094 (88 FR 21879, April 11, 2023), and was therefore 
not subject to a requirement for Executive Order 12866 review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA (44 U.S.C. 3501 et seq.) because it does not contain any 
information collection activities.

C. Regulatory Flexibility Act (RFA)

    This action is certified to not have a significant economic impact 
on a substantial number of small entities under the RFA (5 U.S.C. 601 
et seq.). This action will not impose any requirements on small 
entities beyond those imposed by State law.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. This action imposes no enforceable duty on any 
State, local, or Tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999). It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

[[Page 83375]]

F. Executive Order 13175: Coordination With Indian Tribal Governments

    In addition, this proposed rulemaking action, pertaining to Texas 
regional haze SIP submission for the second planning period, does not 
apply on any Indian reservation land or in any other area where the EPA 
or an Indian Tribe has demonstrated that a Tribe has jurisdiction. In 
those areas of Indian country, the rule does not have Tribal 
implications and will not impose substantial direct costs on Tribal 
governments or preempt Tribal law as specified by Executive Order 13175 
(65 FR 67249, November 9, 2000).

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

    EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) 
as applying only to those regulatory actions that concern environmental 
health or safety risks that EPA has reason to believe may 
disproportionately affect children, per the definitions of ``covered 
regulatory action'' in section 2-202 of the Executive Order. Therefore, 
this action is not subject to Executive Order 13045 because it merely 
proposes to partially approve and partially disapprove a SIP revision 
as meeting federal requirements. Furthermore, the EPA's Policy on 
Children's Health does not apply to this action.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 (66 FR 28355, 
May 22, 2001), because it is not a significant regulatory action under 
Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the NTTAA directs the EPA to use voluntary 
consensus standards in its regulatory activities unless to do so would 
be inconsistent with applicable law or otherwise impractical. This 
action is not subject to the requirements of section 12(d) of the NTTAA 
(15 U.S.C. 272 note) because application of those requirements would be 
inconsistent with the CAA.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Population

    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on communities with environmental justice 
(EJ) concerns to the greatest extent practicable and permitted by law. 
The EPA defines EJ as ``the fair treatment and meaningful involvement 
of all people regardless of race, color, national origin, or income 
with respect to the development, implementation, and enforcement of 
environmental laws, regulations, and policies.'' The EPA further 
defines the term fair treatment to mean that ``no group of people 
should bear a disproportionate burden of environmental harms and risks, 
including those resulting from the negative environmental consequences 
of industrial, governmental, and commercial operations or programs and 
policies.''
    The State did not evaluate environmental justice considerations as 
part of its SIP submittals; the CAA and applicable implementing 
regulations neither prohibit nor require such an evaluation. The EPA 
performed an environmental justice analysis, as is described above in 
the section titled, ``Environmental Justice Considerations.'' The 
analysis was done for the purpose of providing additional context and 
information about this rulemaking to the public, not as a basis of the 
action. Due to the nature of the action being taken here, if finalized, 
this action is expected to have a neutral impact on the air quality of 
the affected area. Consideration of EJ is not required as part of this 
action, and there is no information in the record inconsistent with the 
stated goal of E.O. 12898 of achieving environmental justice for 
communities with EJ concerns.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Nitrogen dioxide, 
Ozone, Particulate matter, Sulfur oxides.

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

    Dated: September 27, 2024.
Earthea Nance,
Regional Administrator, Region 6.
[FR Doc. 2024-23341 Filed 10-10-24; 8:45 am]
BILLING CODE 6560-50-P


</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>