Proposed Rule2025-11270
Air Plan Approval; Texas; Interstate Transport Requirements for the 2010 SO2 NAAQS
Primary source
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Published
June 18, 2025
Issuing agencies
Environmental Protection Agency
Abstract
Pursuant to the Federal Clean Air Act (CAA or the Act), the Environmental Protection Agency (EPA) is proposing to approve the portion of the State Implementation Plan (SIP) submittal from the State of Texas demonstrating that the State satisfies the interstate transport requirements, also known as the "good neighbor" provision of the Clean Air Act, for the 2010 1-hour sulfur dioxide (SO<INF>2</INF>) primary National Ambient Air Quality Standard (NAAQS). The good neighbor provision requires each State's implementation plan to contain adequate provisions prohibiting the interstate transport of air pollution in amounts that will contribute significantly to nonattainment, or interfere with maintenance, of a NAAQS in any other State.
Full Text
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<title>Federal Register, Volume 90 Issue 116 (Wednesday, June 18, 2025)</title>
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[Federal Register Volume 90, Number 116 (Wednesday, June 18, 2025)]
[Proposed Rules]
[Pages 25923-25929]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-11270]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R06-OAR-2013-0388; FRL-12796-01-R6]
Air Plan Approval; Texas; Interstate Transport Requirements for
the 2010 SO2 NAAQS
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the
Environmental Protection Agency (EPA) is proposing to approve the
portion of the State Implementation Plan (SIP) submittal from the State
of Texas demonstrating that the State satisfies the interstate
transport requirements, also known as the ``good neighbor'' provision
of the Clean Air Act, for the 2010 1-hour sulfur dioxide
(SO<INF>2</INF>) primary National Ambient Air Quality Standard (NAAQS).
The good neighbor provision requires each State's implementation plan
to contain adequate provisions prohibiting the interstate transport of
air pollution in amounts that will contribute significantly to
nonattainment, or interfere with maintenance, of a NAAQS in any other
State.
DATES: Written comments must be received on or before July 18, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R06-
OAR-2013-0388, at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from <a href="http://Regulations.gov">Regulations.gov</a>. 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, please contact
Nevine Salem, (214) 665-7222, <a href="/cdn-cgi/l/email-protection#f380929f969edd9d96859a9d96b3968392dd949c85"><span class="__cf_email__" data-cfemail="f685979a939bd89893809f9893b6938697d8919980">[email protected]</span></a>. For the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
Docket: The index to the docket for this action is available
electronically at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. 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: Nevine Salem, telephone number: (214)
665-7222, email address: <a href="/cdn-cgi/l/email-protection#2556444940480b4b40534c4b40654055440b424a53"><span class="__cf_email__" data-cfemail="e390828f868ecd8d86958a8d86a3869382cd848c95">[email protected]</span></a>. We encourage the public
to submit comments via <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Please call or
email the contact listed above if you need alternative access to
material indexed but not provided in the docket. Copyrighted materials
are available for review in person at EPA Region 6 office located at
1201 Elm Street, Suite 500, Dallas, Texas 75270.
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
I. Background
A. Infrastructure SIPs
On June 2, 2010, the EPA established a revised primary 1-hour
SO<INF>2</INF> NAAQS
[[Page 25924]]
with a level of 75 parts per billion (ppb), based on a 3-year average
of the annual 99th percentile of daily maximum 1-hour average
concentrations.\1\ CAA section 110(a)(1) requires all states to submit,
within three years after promulgation of a new or revised NAAQS, SIP
submissions to provide for the implementation, maintenance, and
enforcement of the NAAQS.\2\ The EPA has historically referred to these
SIPs as ``infrastructure SIPs.'' Specifically, section 110(a)(1)
provides the procedural and timing requirements for SIP submissions.
Section 110(a)(2) lists specific elements that all states must meet
related to a newly established or revised NAAQS, such as requirements
for monitoring, basic program requirements, and legal authority that
are designed to assure attainment and maintenance of the NAAQS.
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\1\ See 75 FR 35520 (June 22, 2010).
\2\ In 2012, the EPA retained the current secondary NAAQS for
SO<INF>2</INF>. Thus, the CAA section 110(a)(1) requirement to
submit an infrastructure SIP for this secondary standard was not
triggered. The secondary SO<INF>2</INF> standard is 500 ppb averaged
over three hours, not to be exceeded more than once per year. See 77
FR 20218 (April 3, 2012).
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Section 110(a)(2)(D)(i)(I) of the CAA requires a state's SIP to
include provisions prohibiting any source or other type of emissions
activity in the state from emitting any air pollutant in amounts that
will contribute significantly to nonattainment, or interfere with
maintenance, of the NAAQS in any other state. The EPA has long
interpreted this language to enact a ``functional prohibition'' on
certain emissions from upwind states, necessitating the EPA's
independent assessment of whether those emissions will occur or have
been adequately controlled in the state where they originate.\3\ The
EPA often refers to these requirements as Prong 1 (significant
contribution to nonattainment of the NAAQS) and Prong 2 (interference
with maintenance of the NAAQS). We are addressing Prongs 1 and 2 in
this action. All other applicable infrastructure SIP requirements of
the Texas SIP submission are addressed in separate rulemakings.
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\3\ See Genon Rema LLC v. EPA, 722 F.3d 513, 520-24 (3d Cir.
2013); Appalachian Power Co. v. EPA, 249 F.2d 1032, 1045-47 (D.C.
Cir. 2001); see also 71 FR 25328, 25335 (April 28, 2006) (explaining
that the SIP/FIP process under section 110 and the petitioning
process for direct federal regulation under section 126 provide
independent means of effectuating the same ``functional
prohibition'' found in CAA section 110(a)(2)(D)(i)(I)).
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B. 2010 1-Hour SO2 NAAQS Designations Background
In this proposed action, the EPA has considered information from
the 2010 1-hour SO<INF>2</INF> NAAQS designations process which is
discussed in more detail in section III.C. of this document. For this
reason, a brief summary of the EPA's designations process for the 2010
1-hour SO<INF>2</INF> NAAQS is included here.\4\
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\4\ While designations may provide useful information for
purposes of analyzing transport, particularly for a more source-
specific pollutant such as SO<INF>2</INF>, EPA notes that
designations themselves are not dispositive of whether upwind
emissions are impacting areas in downwind states. EPA has
consistently taken the position that CAA section 110(a)(2)(D)(i)(I)
requires elimination of significant contribution and interference
with maintenance in other states, and this analysis is not limited
to designated nonattainment areas. Nor must designations for
nonattainment areas have first occurred before states or the EPA can
act under section 110(a)(2)(D)(i)(I). See, e.g., Clean Air
Interstate Rule, 70 FR 25162, 25265 (May 12, 2005); Cross State Air
Pollution Rule, 76 FR 48208, 48211 (August 8, 2011); Final Response
to Petition from New Jersey Regarding SO<INF>2</INF> Emissions From
the Portland Generating Station, 76 FR 69052 (November 7, 2011)
(finding facility in violation of the prohibitions of CAA section
110(a)(2)(D)(i)(I) with respect to the 2010 1-hour SO<INF>2</INF>
NAAQS prior to issuance of designations for that standard).
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After the promulgation of a new or revised NAAQS, the EPA is
required to designate areas as ``nonattainment,'' ``attainment,'' or
``unclassifiable'' pursuant to section 107(d)(1)-(2) of the CAA. The
process for designating areas following promulgation of a new or
revised NAAQS is contained in section 107(d) of the CAA. The CAA
requires the EPA to complete the initial designations process within
two years of promulgating a new or revised standard. If the
Administrator has insufficient information to make these designations
by that deadline, the EPA has the authority to extend the deadline for
completing designations by up to one year.
The EPA promulgated the 2010 1-hour SO<INF>2</INF> NAAQS on June 2,
2010. See 75 FR 35520 (June 22, 2010). The EPA Administrator signed the
first round \5\ of designations (``Round 1'') \6\ for the 2010 1-hour
SO<INF>2</INF> NAAQS on July 25, 2013, designating 29 areas in 16
States as nonattainment for the 2010 1-hour SO<INF>2</INF> NAAQS. See
78 FR 47191 (August 5, 2013). The EPA Administrator signed Federal
Register documents for Round 2 designations \7\ on June 30, 2016 (81 FR
45039 (July 12, 2016)) and on November 29, 2016 (81 FR 89870 (December
13, 2016)). Round 3 designations \8\ were signed on December 21, 2017
(83 FR 1098 (January 9, 2018)) and March 28, 2018 (83 FR 14597(April 5,
2018)). Round 4 designations \9\ were signed on December 21, 2020 (86
FR 16055 (March 26, 2021)) \10\ and April 8, 2021 (86 FR 19576 (April
14, 2021)).\11\
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\5\ The term ``round'' in this instance refers to which ``round
of designations.''
\6\ The EPA and state documents and public comments related to
the Round 1 final designations are in the docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> with Docket ID No. EPA-HQ-OAR-2012-0233 and at
EPA's website for SO<INF>2</INF> designations at <a href="https://www.epa.gov/sulfur-dioxide-designations">https://www.epa.gov/sulfur-dioxide-designations</a>.
\7\ The EPA and state documents and public comments related to
the Round 2 final designations are in the docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> with Docket ID No. EPA-HQ-OAR-2014-0464 and at
EPA's website for SO<INF>2</INF> designations at <a href="https://www.epa.gov/sulfur-dioxide-designations">https://www.epa.gov/sulfur-dioxide-designations</a>.
\8\ The EPA and state documents and public comments related to
Round 3 final designations are in the docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> with Docket ID No. EPA-HQ-OAR-2017-0003 and at
EPA's website for SO<INF>2</INF> designations at <a href="https://www.epa.gov/sulfur-dioxide-designations">https://www.epa.gov/sulfur-dioxide-designations</a>.
\9\ The EPA and state documents and public comments related to
Round 4 final designations are in the docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> with Docket ID No. EPA-HQ-OAR-2020-0037 and at
EPA's website for SO<INF>2</INF> designations at <a href="https://www.epa.gov/sulfur-dioxide-designations">https://www.epa.gov/sulfur-dioxide-designations</a>.
\10\ The Round 4 2010 1-hour SO<INF>2</INF> NAAQS designations
action was signed by former EPA Administrator Andrew Wheeler on
December 21, 2020, pursuant to a court-ordered deadline of December
31, 2020. For administrative purposes only, and in compliance with
requirements of the Office of the Federal Register, former Acting
Administrator Jane Nishida re-signed the same action on March 10,
2021, for publication in the Federal Register.
\11\ On August 21, 2015 (80 FR 51052), EPA separately
promulgated air quality characterization requirements for the 2010
1-hour SO<INF>2</INF> NAAQS in the Data Requirements Rule (DRR). The
DRR requires state air agencies to characterize air quality, through
air dispersion modeling or monitoring, in areas associated with
sources that emitted in 2014 2,000 tons per year (tpy) or more of
SO<INF>2</INF>, or that have otherwise been listed under the DRR by
EPA or state air agencies. In lieu of modeling or monitoring, state
air agencies, by specified dates, could elect to impose federally
enforceable emissions limitations on those sources restricting their
annual SO<INF>2</INF> emissions to less than 2,000 tpy, or provide
documentation that the sources have been shut down. EPA used the
information generated by implementation of the DRR to help inform
Round 4 designations for the 2010 1-hour SO<INF>2</INF> NAAQS.
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For Texas, the EPA designated Atascosa, Fort Bend, Goliad, Lamb,
Limestone, McLennan, and Robertson Counties as unclassifiable/
attainment and Potter County as unclassifiable in Round 2. Designations
for Freestone, Anderson, Milam, Rusk, Gregg, Panola, and Titus counties
were delayed. Final designations for these counties were published on
December 13, 2016 (81 FR 89870). Nonattainment designations were
promulgated for three areas: (1) portions of Freestone and Anderson
Counties; (2) portions of Rusk and Panola Counties; \12\ and (3) a
portion of Titus County. An unclassifiable designation was promulgated
for Milam County. After these designations were promulgated, the EPA
underwent additional actions related to the area designations in TX. By
the time Round
[[Page 25925]]
2 was completed, Milam County had been redesignated as attainment/
unclassifiable.
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\12\ We note that on March 25. 2025, the Fifth Circuit Court of
Appeals issued a decision in Texas, et al. v. EPA (No. 17-60088)
vacating the Rusk/Panola nonattainment area designation--mandate
effective on July 8, 2025. See <a href="https://www.ca5.uscourts.gov/opinions/pub/23/23-60069-CV1.pdf">https://www.ca5.uscourts.gov/opinions/pub/23/23-60069-CV1.pdf</a>.
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In Round 4 the EPA designated the remaining counties--Bexar,
Jefferson Robertson, and Titus as attainment/unclassifiable; Harrison
and Orange as unclassifiable; and Howard, Hutchinson, and Navarro as
nonattainment.
II. Relevant Factors Used To Evaluate 2010 1-Hour SO2 Interstate
Transport SIPs
Although SO<INF>2</INF> is emitted from a similar universe of point
and nonpoint sources as directly emitted fine particulate matter
(PM<INF>2.5</INF>) and the precursors to ozone and PM<INF>2.5</INF>,
interstate transport of SO<INF>2</INF> is unlike the transport of
PM<INF>2.5</INF> or ozone, which disperse over a wide area and can
contribute to nonattainment or maintenance issues hundreds of miles
from precursor-emitting sources or activities. SO<INF>2</INF> emissions
usually do not undergo long-range transport in the atmosphere. The
transport of SO<INF>2</INF> relative to the 2010 1-hour SO<INF>2</INF>
NAAQS is more analogous to the transport of lead (Pb) relative to the
Pb NAAQS in that emissions of SO<INF>2</INF> typically result in 1-hour
pollutant impacts of greatest concern near the emissions source.
However, ambient 1-hour concentrations of SO<INF>2</INF> do not
decrease as quickly with distance from the source as do 3-month average
concentrations of Pb, because SO<INF>2</INF> gas is not removed by
deposition as rapidly as are Pb particles. Emitted SO<INF>2</INF> has
wider-ranging impacts than emitted Pb, but it does not have such wide-
ranging (far downwind) impacts that treatment in a manner similar to
ozone or PM<INF>2.5</INF> would be appropriate. Accordingly, the
approaches that EPA has adopted for ozone or PM<INF>2.5</INF> transport
are too regionally focused, and the approach for Pb transport is too
tightly circumscribed to the source, to be appropriate for assessing
SO<INF>2</INF> transport. SO<INF>2</INF> transport is therefore a
unique case and necessitates an analytical approach that examines
potential impacts that are further from the source than would be
examined for Pb transport but less regional in scope than ozone or PM
transport.
In this proposed rulemaking, and consistent with prior
SO<INF>2</INF> transport analyses, the EPA focused on a 50 kilometer
(km)-wide zone around sources of interest because the physical
properties of SO<INF>2</INF> result in relatively localized pollutant
impacts near an emissions source that drop off with distance. Given the
properties of SO<INF>2</INF>, the EPA believes that significant impacts
in a downwind state are unlikely at distances greater than 50 km from a
source and thus, we are focusing our review on areas within 50 km of
the state lines. This scale of analysis is consistent with the ``urban
scale'' which is the largest appropriate spatial scale for
SO<INF>2</INF> monitors and is useful for assessing SO<INF>2</INF>
transport and trends in area-wide air quality.\13\
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\13\ For the definition of spatial scales for SO<INF>2</INF>,
see 40 CFR part 58, appendix D, section 4.4 (``Sulfur Dioxide
(SO<INF>2</INF>) Design Criteria''). For further discussion on how
the EPA applies these definitions with respect to interstate
transport of SO<INF>2</INF>, see the EPA's proposed rulemaking on
Connecticut's SO<INF>2</INF> transport SIP. See 82 FR 21351, 21352,
21354 (May 8, 2017).
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As discussed in section III, and in further detail in the Technical
Support Document (TSD) for this action, the EPA reviewed Texas'
SO<INF>2</INF> SIP submittal, and the particular HYSPLIT back
trajectories Texas relied upon in its SIP. The State's submission did
not have sufficient information to fully assess whether Texas was
meeting its CAA good neighbor requirements for the 2010 SO<INF>2</INF>
NAAQS. Therefore, we elected to review and assess other available
information regarding SO<INF>2</INF> emissions and air quality in Texas
to assist in our own evaluation. We independently analyzed such
information to determine whether Texas meets the interstate transport
requirements described in the CAA.\14\
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\14\ This proposed action is based on the information contained
in the administrative record for this action and does not prejudge
any future EPA action that may make other determinations regarding
the air quality status in Texas and downwind states. Any such future
action, such as area designations under any NAAQS, will be based on
their own administrative records and the EPA's analyses of
information that becomes available at that time. Future available
information may include, monitoring data and modeling analyses
conducted by states, air agencies, and third-party stakeholders.
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Consistent with our prior evaluations of other states'
SO<INF>2</INF> transport obligations, we conducted a weight of evidence
(WOE) analysis evaluating several sources of information, including
current air quality data from monitors as well as available emissions
and/or source modeling for sources in Texas and in neighboring states
within 50 km of the Texas border. A WOE approach can be appropriate in
instances, such as this case, to determine whether SO<INF>2</INF>
emissions from Texas contribute to nonattainment or maintenance issues
in adjoining states. A WOE analysis that is based solely on available
data may not be sufficient in all instances for evaluating interstate
SO<INF>2</INF> transport, and additional analysis may be necessary.
Further, the term ``WOE'' does not establish the legal or technical
meaning for what constitutes significant contribution to nonattainment
or interference with maintenance for the 2010 SO<INF>2</INF> NAAQS.
Rather, the term refers to the gathering and consideration of a wide
range of information, on a case-by-case basis, to make a determination
regarding whether a statutory or regulatory requirement is met.
In other SO<INF>2</INF> transport actions, the EPA has typically
been able to use a WOE analysis to reach a conclusion that there are no
SO<INF>2</INF> nonattainment or maintenance issues in the relevant
areas of other states, or that no sources in the upwind state are
contributing to those issues. If the available evidence indicated,
however, that an upwind source, sources, or emissions activities were
contributing to an out-of-state SO<INF>2</INF> nonattainment or
maintenance problem, then further analysis and a regulatory
determination would be necessary concerning what amount of those
emissions, if any, constituted ``significant contribution'' under Prong
1 or Prong 2 of the good neighbor provision.
We find that there is sufficient information to support the EPA's
proposed determination that, under baseline conditions and likely
future emissions scenarios, no Texas sources are contributing or will
contribute to any out-of-state SO<INF>2</INF> nonattainment or
maintenance concerns, and therefore it is not necessary for the
purposes of this action to render a determination concerning what
amount of emissions would be ``significant'' and therefore subject to
prohibition under the good neighbor provision.\15\
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\15\ Cf. Genon Rema v. EPA, 722 F.3d 513 (3d Cir. 2013)
(upholding EPA grant of CAA section 126(b) petition and
establishment of direct federal emissions control requirements on
SO<INF>2</INF> source in Pennsylvania found to be significantly
contributing to nonattainment and interfering with maintenance of
the 2010 SO<INF>2</INF> NAAQS in New Jersey).
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III. Texas' SIP Submission and EPA's Analysis
A. State Submission
On April 23, 2013, the Texas Commission on Environmental Quality
(TCEQ) submitted to the EPA a SIP revision to address the requirements
of CAA section 110(a)(1) and (2), including section 110(a)(2)(D)(i)(I),
that addresses 2010 SO<INF>2</INF> interstate transport requirements
Prongs 1 and 2.
On January 11, 2016 (81 FR 1127), the EPA approved most elements of
the Texas infrastructure SIP submittal, but we took no action on the
interstate transport provisions of section 110(a)(2)(D)(i)(I)
pertaining to Texas' significant contribution to nonattainment (Prong
1) and interference with maintenance (Prong 2) of the NAAQS in other
states or the
[[Page 25926]]
portion of 110(a)(2)(D)(i)(II) regarding visibility protection (Prong
4).
In the portions of Texas' 2013 submittal addressing interstate
transport (for section 110(a)(2)(D)(i)(I)), the State relied on the
back trajectory analysis \16\ to assess the impacts of SO<INF>2</INF>
emissions emitted in Texas and transported to neighboring states. Texas
used the HYSPLIT \17\ model version 4 (2012) developed by the National
Oceanic and Atmospheric Administration (NOAA) to construct back
trajectories, where ambient air network monitors with the highest
observed SO<INF>2</INF> values were chosen as receptor sites for the
back trajectory analysis. The receptor sites that Texas chose for this
analysis were a single monitor in each of the surrounding states, sites
which were not necessarily sited to characterize high or maximum
SO<INF>2</INF> concentrations (especially from large emitting
SO<INF>2</INF> sources) reaching into other states to determine whether
Texas meets the interstate transport requirement described in the CAA.
Texas chose receptor locations for the HYSPLIT modeling that were very
distant from Texas and the SO<INF>2</INF> sources within Texas.
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\16\ Back trajectory analysis involves tracing the path of an
air parcel backward in time to understand its origin and how it has
traveled. Back trajectory analysis uses meteorological data to
simulate the path of an air parcel (a small volume of air) moving
backward from a specific location and time to its origin.
\17\ HYSPLIT--Hybrid Single Particle Lagrangian Integrated
Trajectory Model.
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In the submittal, Texas acknowledged that the back trajectory
analysis does not (and cannot) assume a link between a mean-trajectory
path and an SO<INF>2</INF> concentration. A mean-trajectory-path
provides only an indication/prediction of the direction (and locations
over which) a parcel of air might have traveled and that more analysis
would be needed to determine the sources and levels of contribution of
air pollutants to a particular location. Texas also stated that the
back trajectory HYSPLIT method quantifies the directions and frequency
of air traveling to the monitor but cannot identify the precise routes
of pollutant particle travel or its concentrations in the air
parcels.\18\
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\18\ See Chapter 2 of the State's submission in the docket for
this rule making.
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While HYSPLIT can be informative for evaluating air quality issues,
the utility and accuracy of back trajectory analysis depends on the
quality and resolution of the meteorological data used and should be
coupled with other information on emissions data sources and ambient
pollution levels near borders or across borders. Texas' submission
neither evaluated SO<INF>2</INF> emissions levels or likely levels of
contribution from Texas sources to the receptor locations it used for
its HYSPLIT analysis, nor established that those receptor locations
were adequate to ensure SO<INF>2</INF> nonattainment and maintenance
issues in other states were properly identified. Therefore, the EPA
elected to review and assess other available information, as described
below and in more detail in the TSD for this action, regarding
SO<INF>2</INF> emissions and air quality for sources in Texas to assist
in our evaluation and to fully assess whether Texas was meeting its CAA
good neighbor obligations for the 2010 SO<INF>2</INF> NAAQS.
B. EPA's Evaluation Methodology
For this CAA section 110 (a)(2)(D)(i)(I) evaluation of the 2010
SO<INF>2</INF> NAAQS, the EPA conducted a WOE analysis for Prong 1 and
Prong 2 separately,\19\ evaluating available information such as air
quality, emission sources, modeling, and emission trends in Texas and
the states that border Texas. To identify which sources and emissions
activities in Texas could potentially impact downwind air quality in
other states with respect to the 2010 1-hour SO<INF>2</INF> NAAQS, the
EPA used information in the EPA's National Emissions Inventory (NEI)
\20\ and Emissions Inventory System (EIS).\21\ The NEI is a
comprehensive and detailed estimate of air emissions for criteria
pollutants, criteria pollutant precursors, and hazardous air pollutants
from air emissions sources, updated every three years using information
provided by the states and other information available to the EPA. For
analyses, we largely relied on data from the 2020 NEI, because it is
the most recently available, complete, and quality assured dataset.
However, in evaluating emissions trends, both state-wide and at the
facility level, the EPA also considered data from prior NEI reports and
EIS queries, as part of the overall WOE analysis.
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\19\ In North Carolina v. EPA, 531 F.3d at 910-911 (D.C. Cir.
2008), the D.C. Circuit explained that the
regulating authority must give Prong 2 ``independent
significance'' from Prong 1 by evaluating the impact of upwind state
emissions on downwind areas that, while currently in attainment, are
at risk of future nonattainment.
\20\ EPA's NEI is available at <a href="https://www.epa.gov/air-emissions-inventories/national-emissions-inventory">https://www.epa.gov/air-emissions-inventories/national-emissions-inventory</a>.
\21\ The EIS Gateway was developed to provide only registered
EPA, State, local, and Tribal users with access to emission
inventory data for sources in their jurisdiction.
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As shown in table 1, the majority of SO<INF>2</INF> emissions in
Texas originate from point sources. In 2020, total SO<INF>2</INF>
emissions from point sources in Texas comprised approximately 77
percent of the total SO<INF>2</INF> emissions in the State. Non-point
sources, on road, and non-road emissions sources contribute to a much
smaller portion of total SO<INF>2</INF> emissions; these emissions are
also more dispersed throughout the State and are therefore unlikely to
contribute to high ambient concentrations of SO<INF>2</INF> when
compared to point source contributions. Further analysis \22\ shows
that facilities with reported emissions greater than 100 tons per year
(tpy) represent approximately 4 percent of the total number of Texas
SO<INF>2</INF> point sources but are responsible for 184,480 tons of
SO<INF>2</INF> or 96 percent of the total 2020 SO<INF>2</INF>
emissions.23 Based on this analysis, the EPA focused our WOE analysis
on SO<INF>2</INF> emissions from Texas' larger point sources (i.e.
point sources emitting over 100 tpy of SO<INF>2</INF>) that are located
within 50 km of one or more state borders.
---------------------------------------------------------------------------
\22\ See EPA's TSD for a more detailed discussion.
Table 1--Summary of SO2 Data for Texas by Source Category
------------------------------------------------------------------------
Percent of
Category 2020 Emissions total SO2
(tpy) emissions
------------------------------------------------------------------------
Point................................... 192,372 77%
Nonpoint................................ 55,135 22
On road................................. 865 <1
Nonroad................................. 66 <1
-------------------------------
SO2 Emissions Total................. 248,438 100
------------------------------------------------------------------------
[[Page 25927]]
As described in this section, the EPA proposes that an assessment
of Texas' satisfaction of the Prong 1 and 2 requirements under CAA
section 110(a)(2)(D)(i)(I) for the 2010 1-hour SO<INF>2</INF> NAAQS may
be reasonably based upon several factors. These factors include
evaluation of the predicted downwind impacts projected in previous
relevant modeling studies for the source and nearby areas, assessment
of Texas' SO<INF>2</INF> point source emissions of more than 100 tpy of
SO<INF>2</INF> that are located within approximately 50 km of another
state, assessment of other states' point sources emitting more than 100
tpy of SO<INF>2</INF> located within approximately 50 km of Texas, and
assessment of federal regulations and SIP-approved regulations
affecting Texas' SO<INF>2</INF> sources. The EPA's evaluation is
informed by all available data at the time of this rulemaking.\24\
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\24\ EPA notes that the evaluation of other states' satisfaction
of section 110(a)(2)(D)(i)(I) for the 2010 1-hour SO<INF>2</INF>
NAAQS can be informed by similar factors found in this proposed
rulemaking but may not be identical to the approach taken in this or
any future rulemaking for Louisiana, depending on available
information and state-specific circumstances.
---------------------------------------------------------------------------
1. EPA's Prong 1 Evaluation--Contribute Significantly to Nonattainment
Prong 1 of the ``good neighbor'' provision requires states' plans
to prohibit emissions that will contribute significantly to
nonattainment of the NAAQS in another state. The EPA's evaluation \25\
of whether Texas has met its Prong 1 transport obligations was
accomplished by considering all available information, including the
following: SO<INF>2</INF> ambient air quality in Texas and neighboring
states; SO<INF>2</INF> emissions trends for Texas and neighboring
states; potential ambient impacts of SO<INF>2</INF> emissions from
certain facilities \26\ in Texas on neighboring states; Texas' SIP-
approved regulations specific to SO<INF>2</INF> emissions and permit
requirements; and other SIP-approved or federally enforceable
regulations which may reduce SO<INF>2</INF> emissions either directly
or indirectly.
---------------------------------------------------------------------------
\25\ A detailed review of the EPA's evaluation of emissions, air
monitoring data, other technical information, and rationale for
proposed approval of this SIP revision as meeting CAA section
110(a)(2)(D)(i)(I) for the 2010 1-hour SO<INF>2</INF> NAAQS may be
found in the TSD.
\26\ The physical properties of SO<INF>2</INF> result in
relatively localized pollutant impacts very near the emissions
source. Therefore, the EPA selected a spatial scale with dimensions
up to 50 km from point sources.
---------------------------------------------------------------------------
Based on the EPA's analysis, we propose to determine that there are
no SO<INF>2</INF> nonattainment concerns in the relevant areas in other
states bordering Texas, and as such the EPA proposes to determine that
Texas' SIP satisfies the requirements of Prong 1 of CAA section
110(a)(2)(D)(i)(I). This proposed determination is based on the
following considerations:
<bullet> There are no monitors within 50 km of the Texas border
recording violations of the 2010 SO<INF>2</INF> NAAQS, all these
monitors have design values (DV) \27\ that are below the 75 ppb
standard. Current DVs for Texas's AQS SO<INF>2</INF> monitors within 50
km of another State's border remained below the 2010 1-hour
SO<INF>2</INF> NAAQS from 2019-2022, similarly, SO<INF>2</INF> monitors
in neighboring states (Arkansas, Louisiana, New Mexico, and Oklahoma)
within 50 km of Texas have 2023 DVs (2021-2023) below the 2010 1-hour
SO<INF>2</INF> NAAQS;
---------------------------------------------------------------------------
\27\ The design value is the 3-year average of the 99th
percentile 1-hour daily maximums at a monitor. A control strategy
should be designed to bring the value to attainment of the standard.
---------------------------------------------------------------------------
<bullet> Downward SO<INF>2</INF> emissions trends in Texas and
surrounding States (Arkansas, Louisiana, and Oklahoma), when considered
with other factors discussed as part of EPA's WOE analysis, further
support that Texas' sources will not significantly contribute to any
State's nonattainment of the 2010 1-hour SO<INF>2</INF> NAAQS.
<bullet> Source-specific analyses of every Texas source emitting
100 tpy or more and located within 50 km of the state border indicate
that the sources do not contribute to nonattainment in other states.
These analyses draw upon available emissions data, monitoring data, air
quality modeling, control requirements, unit retirement, wind rose
data, and other relevant information to assess the likelihood of air
quality impacts from these sources to areas in surrounding states. A
detailed discussion of each source-specific analysis is contained in
section IV.B.1. of the TSD accompanying this action.
Below we cover some of the principal evidence that provides overall
support for the EPA's proposed conclusion that SO<INF>2</INF> emissions
from the following Texas areas are not likely to pose a transport
concern.
Texas Northeast Region Sources
Evaluation of wind rose and monitoring data shows while monitors
are located in the predominant wind direction from the largest sources
in the area and in close proximity to these sources, these monitors are
not measuring violations. In addition, wind roses indicate winds in the
area infrequently blow towards LA. The presence of monitors near to the
source in the direction of the predominant winds that are not measuring
violations indicates that these sources will not cause a violation
further away, across state lines. Finally, there are no large sources
in the neighboring states near the state lines in which emissions could
interact in such a way that Texas sources would be contributing to a
violation.
Texas Southeast Region Sources
Orange area: There is currently one operating source in this area,
the Orion Orange Carbon Black Plant. The Orange monitor was located to
characterize the emissions from this source and has consistently been
in attainment with low DVs. In addition, wind-patterns are
predominantly from the south, not toward the Louisiana state line. The
low concentrations at the monitor and the predominant wind direction
indicate that this source will not cause a violation in Louisiana. In
addition, the nearest large sources in Louisiana are 34 km to the east,
making it unlikely that this source would contribute to nonattainment
in Louisiana. There is another source that was evaluated, the
International Paper Orange Mill, which shut down in 2023. This source
has fewer emissions than the Orion facility and is slightly further
from the state line indicating that were it operating it would be less
likely to cause or contribute to nonattainment.
Beaumont area: There are two sources in this area, the ExxonMobil
refinery and the Arkema Beaumont Plant. The Beaumont monitor is
positioned to the south of these facilities and has consistently been
in attainment, with DVs well below the NAAQS. Wind patterns suggest
emissions are likely to remain localized, and the distance of these
sources from the border indicate these sources do not pose a transport
concern.
Port Arthur area: We evaluated four sources in this far
southeastern portion of the state for impacts in Louisiana: Total
refinery, Motiva refinery, Valero Refinery and Oxbow Calcining. The
monitors in the vicinity of these sources all have DVs below the NAAQS.
The Port Arthur, West 7th monitor, in particular, is a DRR monitor
which was located to characterize impacts from Oxbow. The lack of
measured violations in the vicinity of the facilities and the
predominant wind patterns (not frequently blowing toward Louisiana)
indicate that these sources are not causing violations in Louisiana. In
addition, the nearest large sources in Louisiana are 59 km away in the
Lake Charles area. Because of this long distance, Texas sources would
not be expected to contribute to nonattainment
[[Page 25928]]
in the vicinity of the nearest large sources in Louisiana.
Wichita County Sources
There are two sources in the area of Wichita Falls: Works 4 Glass
Plant and Shepherd Air Force Base. Based on the topography, the
relatively low emissions of the two sources, and distance to the state
line, the EPA proposes to find these sources do not cause nonattainment
in Oklahoma. In addition, there are no nearby emission sources in
Oklahoma that emissions from Texas could potentially interact with to
contribute to nonattainment in Oklahoma.
Northwest Region Sources
We evaluated seven (7) sources in this portion of Texas bordering
southeastern New Mexico. For the three largest sources, modeling was
available either under the DRR or through permitting actions which
indicated impacts in New Mexico would not contribute to nonattainment.
For the remaining sources, the lower reported emissions, distance from
New Mexico, absence of SO<INF>2</INF> sources greater than 100 tpy in
the immediate area of the Texas-New Mexico border, coupled with
topographical and wind features of the area indicate these sources do
not pose a transport concern.
Based on this evaluation, as more thoroughly discussed in our TSD
for this action, EPA proposes to find that sources within Texas will
not significantly contribute to nonattainment of the 2010 1-hour
SO<INF>2</INF> NAAQS in any other state.
2. EPA's Prong 2 Evaluation--Interference With Maintenance
Prong 2 of the ``good neighbor'' provision requires state plans to
prohibit emissions that will interfere with maintenance of a NAAQS in
another state. The EPA's evaluation of whether Texas has met its Prong
2 transport obligations was accomplished by considering all available
information, with a focus on current air quality data, SO<INF>2</INF>
emissions trends for Texas and neighboring states, and how existing and
future sources of SO<INF>2</INF> are addressed through existing SIP-
approved and federally enforceable regulations. This evaluation builds
upon the analysis conducted for significant contribution to
nonattainment (Prong 1), which evaluated SO<INF>2</INF> ambient air
quality in Texas and neighboring states and potential ambient impacts
of SO<INF>2</INF> emissions from certain facilities in Texas on
neighboring states.
Based on the EPA's analysis, we propose to find that SO<INF>2</INF>
levels near the Texas border in neighboring states do not indicate an
inability to maintain the 2010 SO<INF>2</INF> NAAQS that could be
attributed in part to sources in Texas, and as such, the EPA proposes
to determine that Texas' SIP submittal satisfies the requirements of
Prong 2 of CAA section 110(a)(2)(D)(i)(I). This determination is based
on the following considerations:
<bullet> Current 2021-2023 DVs for monitors in Texas within 50 km
of another state's border and in neighboring states (Arkansas,
Louisiana, New Mexico, and Oklahoma) within 50 km of Texas' border are
below the standard, indicating that these areas are currently in
attainment of the 2010 1-hour SO<INF>2</INF> NAAQS;
<bullet> State-wide emissions trends in Texas indicate generally
declining SO<INF>2</INF> emissions and consequently declining impacts
to the relevant areas;
<bullet> Source-specific analyses show that facility-level
emissions are decreasing as a result of emissions unit shutdowns and
control technology installation, indicating that emissions are not
anticipated to increase relative to baseline emissions;
<bullet> Current Texas statutes, SIP-approved measures, and federal
emissions control programs control SO<INF>2</INF> emissions from
certain sources with Texas; and
<bullet> Texas' SIP-approved PSD, major New Source Review (NSR)
regulations and minor source NSR permit programs address future and new
modified SO<INF>2</INF> sources above major and minor permitting
thresholds with the intent of ensuring that the SO<INF>2</INF> NAAQS
will not be exceeded as a result of new facility construction or
existing facility modification within the state or surrounding states.
Based on the evaluation outlined in our TSD for this action, the
EPA proposes to find that SO<INF>2</INF> emissions from Texas will not
interfere with maintenance of the 2010 1-hour SO<INF>2</INF> NAAQS in
any other state.
IV. Proposed Action
The EPA is proposing to approve the remaining portions of Texas'
April 23, 2013, SIP submittal addressing interstate transport for the
2010 1-hour SO<INF>2</INF> NAAQS. Based on the EPA's WOE analysis, more
thoroughly discussed in the TSD, the EPA proposes to determine that
emissions from Texas will not contribute significantly to nonattainment
in, or interfere with maintenance of, any other state with respect to
the 2010 1-hr SO<INF>2</INF> NAAQS. We therefore propose to find that
Texas' SIP contains adequate provisions consistent with CAA section
110(a)(2)(D)(i)(I).
V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely proposes to approve state law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Orders 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
In addition, the SIP is not approved to 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 proposed rule does not have Tribal implications and
will not impose substantial direct costs on Tribal governments or
preempt Tribal law as specified by Executive Order 13175 (65 FR 67249,
November 9, 2000).
[[Page 25929]]
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Reporting and recordkeeping requirements, Sulfur dioxide.
Authority: 42 U.S.C. 7401 et seq.
Dated: June 5, 2025.
Walter Mason,
Regional Administrator, Region 6.
[FR Doc. 2025-11270 Filed 6-17-25; 8:45 am]
BILLING CODE 6560-50-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.