Luminant Generation Co. v. United States Environmental Protection Agency , 714 F.3d 841 ( 2013 )


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  •      Case: 10-60934     Document: 00512185307   Page: 1   Date Filed: 03/25/2013
    IN THE UNITED STATES COURT OF APPEALS
    FOR THE FIFTH CIRCUIT  United States Court of Appeals
    Fifth Circuit
    FILED
    March 25, 2013
    No. 10-60934                   Lyle W. Cayce
    Clerk
    LUMINANT GENERATION CO. LLC, ET AL.,
    Petitioners,
    v.
    UNITED STATES ENVIRONMENTAL PROTECTION AGENCY,
    Respondent.
    On Petitions for Review of a Final Rule of the
    United States Environmental Protection Agency
    Before STEWART, Chief Judge, and BENAVIDES and GRAVES, Circuit
    Judges.
    CARL E. STEWART, Chief Judge:
    IT IS ORDERED that the opinion previously filed in this case,
    Luminant Generation Co. L.L.C. v. U.S. E.P.A., No. 10-60934, 
    699 F.3d 427
    (5th Cir. Oct. 12, 2012), is WITHDRAWN. The following opinion is
    substituted therefor:
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    Two sets of petitioners, hereinafter referred to as “Industry Petitioners”1
    and “Environmental Petitioners,”2 seek review of the United States
    Environmental Protection Agency’s (“EPA”) final rule partially approving and
    partially disapproving the most recent revision to Texas’s State Implementation
    Plan (“SIP”) submitted by the Texas Commission on Environmental Quality
    (“TCEQ”) pursuant to the Clean Air Act (“CAA” or “the Act”), 
    42 U.S.C. § 7401
    et seq.3 Because we find that the EPA did not act arbitrarily or capriciously, or
    contrary to law, or in excess of its statutory authority, in its partial approval and
    partial disapproval of Texas’s SIP revision, we deny both petitions for review.
    I. BACKGROUND
    A. Statutory Background
    The CAA “establishes a comprehensive program for controlling and
    improving the nation’s air quality through state and federal regulation.” BCCA
    Appeal Grp. v. EPA, 
    355 F.3d 817
    , 821-22 (5th Cir. 2003). Under the CAA, the
    EPA is responsible for identifying air pollutants and establishing National
    Ambient Air Quality Standards (“NAAQS”) which specify maximum allowable
    levels of certain types of pollutants in the air. 
    Id. at 822
    ; 
    42 U.S.C. §§ 7408
    -
    7409. The states are then permitted, “within limits established by [the NAAQS],
    to enact and administer their own regulatory programs, structured to meet their
    own particular needs.” Hodel v. Virginia Surface Mining and Reclamation Ass’n,
    1
    Luminant Generation Co. LLC, Oak Grove Management Co. LLC, Big Brown Power
    Co. LLC, and Sandow Power Co. LLC.
    2
    Environmental Integrity Project, Sierra Club, Environment Texas Citizen Lobby, Inc.,
    Citizens for Environmental Justice, Texas Environmental Justice Advocacy Services, Air
    Alliance Houston, and Community In-Power and Development Association.
    3
    Texas Oil & Gas Association of Business, Texas Association of Manufacturers, and
    Texas Chemical Council have filed a brief in support of the EPA’s partial approval of Texas’s
    SIP. The state of Texas has filed an amicus brief in support of Texas’s SIP, as submitted, in
    its entirety.
    2
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    452 U.S. 264
    , 289 (1981). This federal-state partnership is often described as
    “cooperative federalism.” 
    Id.
    To comply with its responsibilities under the Act, each state must create
    and administer a SIP which provides for the “implementation, maintenance, and
    enforcement” of NAAQS by setting “emission limitations and other control
    measures.” 
    42 U.S.C. § 7410
    (a)(1)-(2). The states have “wide discretion” in
    formulating their SIPs, Union Elec. Co. v. EPA, 
    427 U.S. 246
    , 250 (1976),
    including the “broad authority to determine the methods and particular control
    strategies they will use to achieve the statutory requirements.” BCCA Appeal
    Grp., 
    355 F.3d at
    822 (citing Union Elec. Co., 
    427 U.S. at 266
     (“So long as
    national standards are met, the state may select whatever mix of control devices
    it desires.”)). Once a state creates or revises a SIP, it is submitted to the EPA
    for review. 
    42 U.S.C. §§ 7410
    (a)(1),(k)(1)-(2).
    The Act confines the EPA to the ministerial function of reviewing SIPs for
    consistency with the Act’s requirements. 
    Id.
     at § 7410(k)(3). The EPA must
    approve the plan in its entirety if it meets the applicable requirements of the
    Act. Id. at § 7410(k)(3); Fla. Power & Light Co. v. Costle, 
    650 F.2d 579
    , 587 (5th
    Cir. 1981). If only “a portion of the [SIP] meets all the applicable requirements
    of [the Act],” the EPA “may approve the [submittal] in part and disapprove the
    [submittal] in part.”    
    42 U.S.C. § 7410
    (k)(3).    The EPA may also provide
    “conditional approval” of a SIP, “based on a commitment of the State to adopt
    specific enforceable measures by a date certain, but not later than 1 year after
    the date of approval of the plan revision.” 
    Id.
     at § 7410(k)(4).
    States must periodically revise their SIPs as necessary to ensure
    continuing compliance with current NAAQS. Id. at § 7410(a)(2)(H). The EPA
    must review and approve or disapprove a SIP revision within 18 months of
    submission. Id. at §§ 7410(k)(1)(B),(2)-(3). The EPA shall disapprove a SIP
    revision only if “the revision would interfere with any applicable requirement
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    concerning attainment” of the NAAQS “or any other applicable requirement” of
    the Act. Id. at § 7410(l). If the revision meets all of the applicable CAA
    requirements, the EPA “shall approve such submittal as a whole.” Id. at §
    7410(k)(3). Once approved by the EPA as meeting the requirements of the Act,
    the SIP, or the approved portion thereof, is incorporated by reference into the
    Code of Federal Regulations. See 
    40 C.F.R. § 52.02
     (2011).
    The CAA provides for shared enforcement of SIPs. A state must include
    in its SIP, a “program to provide for the enforcement” of the plan. 
    42 U.S.C. § 7410
    (a)(2)(C). The program must provide the state permitting authority power
    to “recover civil penalties in a maximum amount of not less than $10,000 per day
    for each violation.” 
    Id.
     at § 7661a(b)(5)(E). Additionally, the EPA has the power
    to enforce a SIP by commencing “a civil action for a permanent or temporary
    injunction, or to assess and recover a civil penalty of not more than $25,000 per
    day for each violation, or both[.]” Id. at § 7413(b). Such suit may be brought in
    district court, “and such court shall have jurisdiction to restrain such violation,
    to require compliance, to assess such civil penalty, to collect any fees owed to the
    United States . . . and to award any other appropriate relief.” Id. Finally, any
    person may commence a civil action on his own behalf against any person who
    is alleged to have violated an emission standard or limitation in a SIP. Id. at
    § 7604(a). A citizen suit may be brought in district court, which shall have
    jurisdiction to enforce such an emission standard or limitation and to apply any
    appropriate civil penalties. Id.
    In assessing the amount of a civil penalty in either an EPA enforcement
    action or a citizen suit, the court must consider the penalty assessment criteria
    outlined in section 7413(e), i.e., the size of the business, the economic impact of
    the penalty on the business, the violator’s full compliance history and good faith
    efforts to comply, the duration of the violation as established by any credible
    evidence (including evidence other than the applicable test method), payment by
    4
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    the violator of penalties previously assessed for the same violation, the economic
    benefit of noncompliance, the seriousness of the violation, and “other factors as
    justice may require.” Id. at § 7413(e).
    B. Facts and Proceedings
    In its final rule4 which became effective on January 10, 2011, the EPA
    partially approved and partially disapproved the most recent revision to Texas’s
    SIP which was submitted by the TCEQ in 2006.5 The portion of the SIP at issue
    creates an affirmative defense against civil penalties for excess emissions during
    both planned and unplanned startup, shutdown, and maintenance/malfunction
    (“SSM”) events. The EPA approved the portion of the SIP revision providing an
    affirmative defense against civil penalties for unplanned SSM events and
    disapproved the portion of the SIP revision providing an affirmative defense
    against civil penalties for planned SSM events. See 
    75 Fed. Reg. 68,989
    , 68,991.
    Since the creation of its first SIP in 1972, Texas has provided for special
    treatment of SSM activity.             See Tex. SIP § XIV, Rule 12 (Jan. 26, 1972)
    (providing emissions during “upsets” and “start-up or shutdown . . . may not be
    required to meet the allowable emission levels”). The revised SIP submitted by
    Texas in 2000 provided that emissions from SSM activity were “exempt from
    compliance with air emission limitations established in permits, rules, and
    orders of the commission” so long as the owner or operator complied with certain
    reporting, record keeping, and operational requirements. See General Air
    Quality Rules, 
    25 Tex. Reg. 6727
    , at § 101.11(b) (July 14, 2000). Further, the
    exceptions were limited to SSM emissions that “could not have been prevented
    4
    Approval and Promulgation of Implementation Plans; Texas; Excess Emissions
    During Startup, Shutdown, Maintenance, and Malfunction Activities, 
    75 Fed. Reg. 68,989
    (Nov. 10, 2010).
    5
    
    30 Tex. Reg. 4090
     (July 15, 2005) (proposed), amended by 
    31 Tex. Reg. 422
     (Jan 20,
    2006).
    5
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    through planning and design,” that “were not part of a recurring pattern,” and
    that did “not cause or contribute to a condition of air pollution.” See 
    id.
    The EPA approved the 2000 SIP revision, determining that the exemptions
    for emissions during SSM activity contained in the plan met the requirements
    of the CAA. See Approval and Promulgation of Implementation Plans; Texas;
    Excess Emissions During Startup, Shutdown, Malfunction and Maintenance, 
    65 Fed. Reg. 70,792
     (Nov. 28, 2000). In its approval, the EPA noted that “under the
    [CAA], all excess emissions during SSM episodes are violations of applicable
    emission limitations [however,] we believe it would be inequitable to penalize a
    source for occurrences beyond the company’s control. A source has the burden
    of proving that the excess emissions were due to circumstances beyond the
    control of the operator or the owner.” Id. at 70,793. Additionally, the EPA found
    that the 2000 SIP revision comported with past EPA guidance contained in its
    policy statements regarding emissions from SSM activity. Id. at 70,792–93.
    These policy statements can be found in a collection of memos that we will refer
    to as the “Bennett Memos” (19826 & 19837) the “Herman Memo” (19998). Id. at
    70,792.
    6
    Mem. of Kathleen Bennett, “Policy on Excess Emissions During Startup, Shutdown,
    Maintenance, and Malfunctions” (Sept. 28, 1982) (providing that “it is reasonable to expect
    that careful planning will eliminate violations of emissions limitations during [startup and
    shutdown] periods. . . . [s]imilarly, scheduled maintenance is a predictable event which can
    be . . . made to coincide with maintenance . . . or other source shutdowns. Consequently,
    excess emissions during periods of scheduled maintenance should be treated as a violation[.]”).
    7
    Mem. of Kathleen Bennett, “Policy on Excess Emissions During Startup, Shutdown,
    Maintenance, and Malfunctions” (Feb. 15, 1983) (recognizing that, in certain situations, excess
    emissions during startup and shutdown “need not be treated as a violation if the source can
    show that the excesses could not have been prevented . . . and that bypassing was unavoidable
    to prevent loss of life, personal injury, or severe property damage.”).
    8
    Mem. of Steven A. Herman, “State Implementation Plans (SIPs): Policy Regarding
    Excess Emissions During Malfunctions, Startup, and Shutdown” (Sept. 20, 1999) (providing
    that “because excess emissions might . . . prevent attainment or interfere with maintenance
    of [NAAQS], EPA views all excess emissions as violations. . . . Nevertheless, . . . imposition of
    a penalty for sudden and unavoidable malfunctions . . . may not be appropriate.”).
    6
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    Additionally, in accordance with the EPA’s request, 
    28 Tex. Reg. 5787
    ,
    5787 (July 25, 2003) (proposed), Texas’s 2004 SIP revision omitted the language
    indicating that SSM emissions were “exempt,” and substituted language that
    such emissions would be “subject to an affirmative defense.” 
    29 Tex. Reg. 118
    ,
    120 (Jan. 2, 2004) (final). Further, as a result of changes in state law, Texas also
    distinguished between emissions resulting from planned SSM activity and all
    other emission events and proposed providing an affirmative defense for these
    emissions. 
    Id.
     at 134 (§ 101.222(b),(c)). The proposed affirmative defense for
    scheduled SSM activity required the owner or operator prove “the period of
    unauthorized emissions . . . could not have been prevented through planning and
    design.” Id. at 134 (§ 101.222(c)(2)).       All other emissions would only be
    protected if they were “caused by a sudden breakdown of equipment or process,
    beyond the control of the owner or operator.” Id. at 134 (§ 101.222(b)(2)). The
    proposed rules stated that the affirmative defense provision would expire on
    June 30, 2005. Id. at 135 (§ 101.222(h)).
    The EPA ultimately gave Texas’s 2004 SIP revision “limited approval.”
    See Limited Approval and Promulgation of Implementation Plans; Texas; Excess
    Emissions During Startup, Shutdown and Malfunction Activities, 
    70 Fed. Reg. 16,129
     (Mar. 30, 2005). The EPA explained that “the rule improves the SIP and
    is largely consistent with the relevant requirements of the [CAA]” but noted that
    the provisions allowing for an affirmative defense for scheduled SSM activity
    were “ambiguous, at best, and inconsistent with the [CAA], at worst, and could
    create problems with enforcing the underlying applicable emission limits.” 70
    Fed. Reg. at 16,130. The EPA stated as follows:
    The EPA’s interpretation of [§ 7410] allows an
    affirmative defense to be asserted against civil
    penalties . . . for excess emissions activities which are
    sudden, unavoidable or caused by circumstances beyond
    the control of the owner or operator . . . . However, EPA
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    has determined that it is inappropriate to provide an
    affirmative defense for excess emissions resulting from
    scheduled maintenance . . . .
    Id. at 16,131. Nevertheless, the EPA approved the 2004 provision, noting
    section 101.222's expiration date of June 30, 2005, but in doing so, the agency
    clarified that “if Texas revises its rules to include an affirmative defense for
    excess emissions in the Texas SIP in the future, the State should ensure . . . that
    the affirmative defense does not apply to excess emissions from scheduled
    maintenance activities . . . .” Id. The EPA then granted a request from Texas to
    extend the affirmative defense’s expiration date to June 30, 2006. See Limited
    Approval and Promulgation of Implementation Plans; Texas; Excess Emissions
    During Startup, Shutdown and Malfunction Activities, 
    70 Fed. Reg. 50,205
    ,
    50,206 (Aug. 26, 2005).
    On January 23, 2006, Texas submitted the revised SIP that is the subject
    of this appeal. The 2006 SIP revision provides in part:
    (1)    For any emission deemed excessive by the state executive director, no
    affirmative defense would be available. See 
    30 Tex. Admin. Code § 101.222
    (a).
    (2)    For “unplanned maintenance, startup or shutdown activity,” an
    affirmative defense against civil penalties would be available if the “owner
    or operator proves . . . all” of the listed criteria, including that “(2) the
    periods of unauthorized emissions from unplanned [SSM] activity could
    not have been prevented through planning and design,” and “(3) the
    unauthorized emissions from unplanned [SSM] activity were not part of
    a recurring pattern,” and that the “(9) unauthorized emissions did not
    cause or contribute to an exceedance of the NAAQS . . . .” See 
    30 Tex. Admin. Code §§ 101.1
    (108), 101.222(c); see also 
    id.
     §§ 101.1(109),
    101.222(b) (providing elements for “upset events”).
    (3)    For “[p]lanned maintenance, startup, or shutdown activity,” an affirmative
    defense against civil penalties would be available if the “owner or operator
    proves all” of the criteria listed under the section for unplanned SSM
    activity, including that “(2) the periods of unauthorized emissions from
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    unplanned [SSM] activity could not have been prevented through planning
    and design,” that “(3) the unauthorized emissions from unplanned [SSM]
    activity were not part of a recurring pattern,” and that “(9) unauthorized
    emissions did not cause or contribute to an exceedance of the NAAQS . .
    . .” See 
    30 Tex. Admin. Code § 101.222
    (h) (emphasis added). The
    affirmative defense for planned SSM activity would expire after, at most,
    two years. See 
    id.
     § 101.222(h)-(i).
    Thereafter, as mentioned above, the EPA partially approved and partially
    disapproved the revisions. 75 Fed. Reg. at 68,991. In finalizing its approval of
    the portion of the SIP revision containing an affirmative defense for unplanned
    SSM activity, the EPA stated that section 101.222(a)-(g) “provides an affirmative
    defense for certain emission events that is consistent with the interpretation of
    the Act as set forth in our guidance documents.” Id. at 68,990. The EPA
    explained that it has “recognized that sources may, despite good practices, be
    unable to meet emission limitations during periods of startup and shutdown and,
    that despite good operating practices, sources may suffer a malfunction due to
    events beyond the control of the owner or operator.” Id. at 68,992.
    The EPA then finalized its disapproval of section 101.222(h)-(j), which
    contained an affirmative defense for planned SSM activity, 75 Fed. Reg. at
    68,991, relying on its past reasoning that “[b]ecause these events are planned,
    we believe that sources should be able to comply with applicable emission limits
    during these periods of time.” 
    75 Fed. Reg. 26,892
    , 26,896 (May 13, 2010). The
    EPA further stated that it disapproved of the affirmative defense for planned
    startup and shutdown activity contained in the SIP revision because it found the
    provisions for such activity to be nonseverable from those for planned
    maintenance. 75 Fed. Reg. at 68,991.
    Environmental Petitioners seek review of the EPA’s final rule approving
    the portion of the SIP revision providing an affirmative defense against civil
    penalties for excess emissions resulting from unplanned SSM activity. Industry
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    Petitioners seek review of the EPA’s final rule disapproving the portion of SIP
    revision providing an affirmative defense against civil penalties for excess
    emissions resulting from planned SSM activity.
    II. STANDARD OF REVIEW
    Pursuant to 
    42 U.S.C. § 7607
    (b), this court has jurisdiction to hear a
    petition for review of the EPA’s approval of a SIP under 
    42 U.S.C. § 7410
    . A
    petition to review the EPA’s approval or disapproval of a SIP is governed by the
    Administrative Procedure Act. See 
    5 U.S.C. § 706
    ; BCCA Appeal Grp., 
    355 F.3d at 824
    . The EPA’s decision is valid unless it is “arbitrary, capricious, an abuse
    of discretion, or otherwise not in accordance with law.” 
    5 U.S.C. § 706
    (2)(A).
    Agency action that is in excess of statutory authority will also be set aside. 
    Id.
    at § 706(2)(C).
    “An agency rule is arbitrary and capricious ‘if the agency has relied on
    factors which Congress has not intended it to consider, entirely failed to consider
    an important aspect of the problem, offered an explanation for its decision that
    runs counter to the evidence before the agency, or is so implausible that it could
    not be ascribed to a difference in view or the product of agency expertise.’” Tex.
    Oil & Gas Ass’n v. U.S. E.P.A., 
    161 F.3d 923
    , 933 (5th Cir. 1998) (quoting Motor
    Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co., 
    463 U.S. 29
    , 43 (1983)).
    “If the agency’s reasons and policy choices conform to minimal standards of
    rationality, then its actions are reasonable and must be upheld.” Tex. Oil & Gas
    Ass’n, 
    161 F.3d at 934
    . Nonetheless, the reviewing court “may not supply a
    reasoned basis for the agency’s action that the agency itself has not given.”
    Motor Vehicle Mfrs. Ass’n, 
    463 U.S. at 43
    . “[T]he focal point for judicial review
    should be the administrative record already in existence, not some new record
    made initially in the reviewing court.” Camp v. Pitts, 
    411 U.S. 138
    , 142 (1973).
    “The court applies the two-step Chevron analysis to questions involving
    the EPA’s interpretation of the statutes it administers,” including the CAA.
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    Chevron, U.S.A., Inc. v. NRDC, Inc., 
    467 U.S. 837
    , 842-43 (1984). “If Congress
    ‘has directly spoken to the precise question at issue,’ the agency and the court
    ‘must give effect to the unambiguously expressed intent of Congress.’” Chevron,
    
    467 U.S. at 842-43
    . In performing this analysis, the court “employ[s] traditional
    tools of statutory construction.” Chevron, 
    467 U.S. at
    843 n.9. “[A] statutory
    provision cannot be read in isolation, but necessarily derives its meaning from
    the context provided by the surrounding provisions, as well as the broader
    context of the statute as a whole.” Khalid v. Holder, 
    655 F.3d 363
    , 367 (5th Cir.
    2011).
    “If the statute, however, is ‘silent or ambiguous with respect to the specific
    issue,’ the court must first assess the administrative decision-making process to
    determine whether the agency’s action is entitled to Chevron deference.” United
    States v. Mead Corp., 
    533 U.S. 218
    , 226-31 (2001) (quoting Chevron, 
    467 U.S. at 843
    ). “Under Mead, Congress must have ‘delegated authority to the agency
    generally to make rules carrying the force of law,’ and that agency interpretation
    claiming deference must have been promulgated in the exercise of that
    authority.” BCCA Appeal Grp., 
    355 F.3d at 825
     (quoting Mead, 
    533 U.S. at
    226-
    27). “If the agency’s decision is a result of a sufficiently formal and deliberative
    process to warrant deference, the second step of Chevron requires the court to
    assess whether the agency’s interpretation is ‘based on a permissible
    construction of the statute.’” Mead, 
    533 U.S. at 230
     (quoting Chevron, 
    467 U.S. at 843
    ). “If the agency’s interpretation is reasonable, it will be upheld.” Smiley
    v. Citibank, N.A., 
    517 U.S. 735
    , 744-45 (1996). “Federal courts accord ‘great
    deference’ to the EPA’s construction of the [CAA].” Union Elec. Co., 
    427 U.S. at 266
    .
    Where an issue presented is a challenge to an agency’s interpretation of
    its own regulation, the agency’s interpretation is controlling unless it is “plainly
    erroneous or inconsistent with the regulation.” Auer v. Robbins, 
    519 U.S. 452
    ,
    11
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    461 (1997) (quoting Robertson v. Methow Valley Citizens Council, 
    490 U.S. 332
    ,
    359 (1989)).
    III. DISCUSSION
    A. Arguments Raised By Environmental Petitioners
    Environmental Petitioners argue that the EPA’s approval of the
    affirmative defense for unplanned SSM events is in excess of the agency’s
    statutory authority and is not in accordance with the Act.             Specifically,
    petitioners argue that the final rule conflicts with the plain language of the Act
    authorizing civil penalties in EPA and citizen suit enforcement actions, as well
    as the Act’s requirement that the state permitting authority be able to assess
    civil penalties.   Environmental Petitioners further argue that, even if the
    affirmative defense against civil penalties for excess emissions resulting from
    unplanned SSM activity is not contrary to the CAA, the EPA’s approval was
    arbitrary and capricious. Finally, Environmental Petitioners argue that, in
    approving the affirmative defense for unplanned SSM activity, the EPA altered
    the meaning of the SIP as submitted by Texas. We address each of these
    arguments in turn.
    1. In excess of statutory authority & not in accordance with law
    The EPA’s decision partially approving the SIP revision containing an
    affirmative defense for unplanned SSM activity is invalid if it found by this court
    to be, inter alia, “not in accordance with law” or in excess of the agency’s
    statutory authority. 
    5 U.S.C. § 706
    (2)(A),(C). As stated above, the Act confines
    the EPA to reviewing SIPs for consistency with the Act’s requirements. 
    42 U.S.C. §§ 7410
    (k)(3); 7410(a)(1). The EPA “shall not approve a revision of a plan
    if the revision would interfere with any applicable requirement concerning
    attainment” or “or any other applicable requirement” of the Act. 
    Id.
     at § 7410(l).
    Further, as pointed out by petitioners, the CAA provides that, in the case of EPA
    enforcement and citizen suits, a federal district court “shall have jurisdiction” to
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    assess a “civil penalty.” Id. at §§ 7413(b); 7604(a). In assessing the amount of
    a civil penalty in either an EPA enforcement action or a citizen suit, the court
    must consider the penalty assessment criteria outlined in section 7413(e). Id.
    at § 7413(e).   Additionally, the CAA mandates that the state permitting
    authority have the power to recover civil penalties for violations under the Act.
    42 U.S.C. § 7661a(b)(5)(E).
    The EPA construes section 7413 of the Act as authorizing affirmative
    defenses against civil penalties if the defense is “narrowly tailored” to address
    unavoidable, excess emissions and consistent with the penalty assessment
    criteria set forth in section 7413(e). Accordingly, this court must determine if
    the EPA’s interpretation of section 7413 is entitled to Chevron deference.
    Chevron, 
    467 U.S. at 843
    . We hold that it is.
    As an initial matter, we note that the EPA’s procedure of “notice-and-
    comment rulemaking” and “adjudication” is generally a sufficiently formal and
    deliberative process. Mead Corp., 
    533 U.S. at 229-30
    . Therefore, “[t]he court
    applies the two-step Chevron analysis to questions involving the EPA’s
    interpretation of the statutes it administers.” Chevron, 
    467 U.S. at 842-43
    . “If
    Congress ‘has directly spoken to the precise question at issue,’ the agency and
    the court ‘must give effect to the unambiguously expressed intent of Congress.’”
    
    Id.
     If the statute, however, is “silent or ambiguous with respect to the specific
    issue,” the court must assess whether the agency’s interpretation of the Act is
    “based on a permissible construction of the statute” and, therefore, entitled to
    Chevron deference. Chevron, 
    467 U.S. at 843
    .
    Thus, under Chevron step one, we begin by looking at whether the statute
    is silent or ambiguous with regard to the specific issue in dispute. Here, section
    7413 does not discuss whether a state may include in its SIP the availability of
    an affirmative defense against civil penalties for unplanned SSM activity. 
    42 U.S.C. § 7413
    . Accordingly, we turn to step two of Chevron and ask whether the
    13
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    EPA’s interpretation of section 7413, as authorizing an affirmative defense for
    unplanned SSM activity, is entitled to deference. Chevron, 
    467 U.S. at 843
    .
    The EPA submits that its “interpretation of the CAA is that it is not
    appropriate for SIPs to exempt periods of startup, shutdown, maintenance or
    malfunction from compliance with applicable emission limits.” 75 Fed. Reg. at
    68,991-92. To support this interpretation, the agency relies on section 302(k) of
    the Act which defines “emission limitation” and includes a requirement that
    emissions be limited on a continuous basis. Id. at 68,992; 
    42 U.S.C. § 7602
    (k).
    Further, noting its authority to assess civil penalties under section 7413
    of the Act, the agency reasons that an effective enforcement program must be
    able to collect penalties to deter avoidable violations. 
    42 U.S.C. § 7413
    . The
    EPA recognizes, however, that “sources may, despite good practices, be unable
    to meet emission limitations during periods of startup and shutdown and, that
    despite good operating practices, sources may suffer a malfunction due to events
    beyond the control of the owner or operator.” Id. at 68,992. For this reason, the
    agency submits that a SIP “should only provide [an affirmative defense against
    civil penalties] for circumstances where it is infeasible to meet the applicable
    limit and the criteria that the source must prove should ensure that the source
    has made all reasonable efforts to comply.” Id. at 68,992-93; 
    42 U.S.C. § 7413
    (e).
    As a result, the EPA states that it has adopted an interpretation of section
    7413 that would allow sources to assert an affirmative defense for periods of
    unavoidable, excess emissions during certain SSM activity in an enforcement
    action for penalties, though not in an action for injunctive relief. Id. at 68,992.
    The agency concludes that this interpretation is consistent with the Act because
    the criteria a source must prove when asserting the affirmative defense are
    consistent with the penalty assessment criteria identified in section 7413(e),
    which are considered by the courts and the EPA in determining whether or not
    to assess a civil penalty for violations and, if so, the amount. Id. at 68,992; 42
    14
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    60934 U.S.C. § 7413
    (e). Thus, the affirmative defense criteria are tailored to ensure
    that the source has made all reasonable efforts to comply with emission
    limitations and remain in compliance with the Act. Id. at 68,992. Consequently,
    the agency reasons that an appropriately crafted affirmative defense is one that
    is narrowly tailored to address unavoidable, excess emissions and consistent
    with the penalty assessment criteria in section 7413(e). Id. at 68,992; 
    42 U.S.C. § 7413
    .
    The approved portion of Texas’s SIP that contains an affirmative defense
    for unplanned SSM activity provides, as an initial matter, that sources are
    generally subject to enforcement actions for any “upset” events, i.e., an
    unplanned and unavoidable malfunction that results in unauthorized emissions.
    
    30 Tex. Admin. Code § 101.1
    (109).                 If an “upset” event is considered an
    “excessive” emission event based on a number of factors including frequency,
    duration, impact on human health, and other measures, no affirmative defense
    is available. 
    Id.
     at § 101.222(a)-(b). If the violation is not deemed “excessive,”
    and it occurred during unplanned SSM activity, and nine additional criteria are
    met, including a demonstration that the unauthorized emissions “did not cause
    or contribute to an exceedance of the NAAQS, PSD increments, or a condition of
    air pollution,” and that the unauthorized emissions “could not have been
    prevented through planning and design,” then the affirmative defense is
    available. Id. at § 101.222(b),(c). Regardless, even if all nine required criteria
    are met and the violator establishes the applicability of the approved affirmative
    defense, injunctive relief is still available. 75 Fed. Reg. at 68,991 n.4.9
    9
    Additionally, the availability of the affirmative defense does not negate the district
    court’s jurisdiction to assess civil penalties using the criteria outlined in section 7413(e), or the
    state permitting authority’s power to recover civil penalties, it simply provides a defense,
    under narrowly defined circumstances, if and when penalties are assessed.
    15
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    The EPA submits that the above-mentioned affirmative defense for
    unplanned SSM events is narrowly tailored to address unavoidable, excess
    emissions and consistent with the penalty assessment criteria in section 7413(e).
    Thus, it approved this portion of Texas’s SIP revision as being consistent with
    section 7413 of the Act. 
    42 U.S.C. §§ 7413
    , 7410(l). We hold this to be a
    permissible interpretation of section 7413, warranting deference. Chevron, 
    467 U.S. at 843
    . Accordingly, the EPA acted neither contrary to law nor in excess of
    its statutory authority when it based its partial approval of the plan on this
    construction. 
    5 U.S.C. § 706
    (2)(A),(C).
    2. Arbitrary and Capricious
    Environmental Petitioners argue that, even if the affirmative defense for
    unplanned SSM activity is not contrary to the CAA, the EPA’s approval was
    nonetheless arbitrary and capricious. They argue that the EPA failed to explain
    why it approved the affirmative defense in light of (1) the EPA’s position that
    affirmative defenses should not be available where a small group of sources
    could cause exceedance of the NAAQS; (2) precedent indicating that civil
    penalties serve to encourage compliance with the Act; and (3) the burden an
    affirmative defense would place on citizen suits.
    The EPA’s decision is not valid if found by this court to be arbitrary or
    capricious. 
    5 U.S.C. § 706
    (2)(A). “An agency rule is arbitrary and capricious ‘if
    the agency has relied on factors which Congress has not intended it to consider,
    entirely failed to consider an important aspect of the problem, offered an
    explanation for its decision that runs counter to the evidence before the agency,
    or is so implausible that it could not be ascribed to a difference in view or the
    product of agency expertise.’” Tex. Oil & Gas Ass’n, 
    161 F.3d at 933
    . “If the
    agency’s reasons and policy choices conform to minimal standards of rationality,
    then its actions are reasonable and must be upheld.” 
    Id. at 934
    .
    16
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    With respect to their first argument, Environmental Petitioners are
    correct that the EPA has stated in its past policy guidance that “[w]here a single
    source or small group of sources has the potential to cause an exceedance of the
    NAAQS or PSD increments . . . an affirmative defense approach will not be
    adequate to protect public health and the environment . . . .”10 Petitioners are
    also correct that the approved affirmative defense provision does not contain
    specific language excluding emissions caused by “a single source or small group
    of sources” that could potentially “cause an exceedance of the NAAQS or PSD
    increments.” But, as pointed out by the agency in its brief, the affirmative
    defense excludes all emissions that could “cause or contribute to an exceedance
    of the NAAQS, PSD increments, or a condition of air pollution.” 
    30 Tex. Admin. Code § 101.222
     (b)(11), (c)(9). Thus, the approved portion of the affirmative
    defense is not inconsistent with the agency’s past policy guidance.
    Environmental Petitioners’ remaining two arguments as to why the EPA’s
    approval of the affirmative defense was arbitrary and capricious are also
    unavailing. Environmental Petitioners are correct that the EPA has recognized
    that the availability of civil penalties serves as an incentive for companies to
    take actions to avoid excess emissions. 75 Fed. Reg. at 68,999. In its partial
    approval of the SIP revision, however, the EPA further recognized that while
    “the availability of civil penalties serves as an incentive for companies to be more
    cautious, to take more preventative actions, and to seek to develop technologies
    and management practices to avoid excess emissions[,] . . . the criteria a source
    would need to prove in order to successfully assert an affirmative defense will
    encourage companies to take such caution.” Id. at 68,999.
    The EPA’s reasoning relies on the fact that the narrowly tailored
    affirmative defense presents a high burden for any company seeking entitlement
    10
    See infra Mem. of Steven A. Herman, “State Implementation Plans (SIPs): Policy
    Regarding Excess Emissions During Malfunctions, Startup, and Shutdown” (Sept. 20, 1999).
    17
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    to it. Assuming the violation is not deemed “excessive,” and it occurred during
    unplanned SSM activity, nine additional criteria must be met, including a
    demonstration that the unauthorized emissions “did not cause or contribute to
    an exceedance of the NAAQS, PSD increments, or a condition of air pollution,”
    and that the unauthorized emissions “could not have been prevented through
    planning and design.” 
    30 Tex. Admin. Code § 101.222
    (c).            This reasoning
    supports the EPA’s position that its approval of the affirmative defense for
    unplanned SSM activity will not serve as a disincentive for companies to avoid
    excess emissions.     Thus, there is no conflict with the agency’s previous
    statements that civil penalties encourage compliance with the Act.
    Environmental Petitioners’ second argument that the affirmative defense
    places an unreasonable burden on plaintiffs is also without merit.
    Environmental Petitioners contend that the affirmative defense only requires a
    “prima facie showing” by defendants, after which the burden will shift to the
    plaintiffs to show that the affirmative defense does not apply. As pointed out by
    the EPA, however, when a source asserts the affirmative defense, it has the
    burden of proving the “enumerated factors, including that the period of excess
    emissions was minimized to the extent practicable and that the emissions were
    not due to faulty operations or disrepair of equipment.” 75 Fed. Reg. at 68,992
    (citing see 
    30 Tex. Admin. Code § 101.222
    (b),(c)). The provision makes no
    reference to a prima facie showing. 
    Id.
     Accordingly, the burden remains on the
    party seeking entitlement to the affirmative defense, not a plaintiff seeking relief
    under the Act. Given these facts, we agree with the EPA’s position that the
    approved affirmative defense for unplanned SSM activity does not place an
    unreasonable burden on plaintiffs.
    Consequently, we hold that the EPA did not act arbitrarily or capriciously
    in its partial approval of the SIP revision. The above-mentioned reasons and
    policy choices provided by the EPA for approving the affirmative defense for
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    unplanned SSM activity “conform to minimal standards of rationality”;
    therefore, they are reasonable and will be upheld by this court. Tex. Oil & Gas
    Ass’n, 
    161 F.3d at 934
    .
    3. Alteration of the meaning of the SIP
    Environmental Petitioners’ final argument is that, by approving the
    affirmative defense for unplanned SSM activity, the EPA impermissibly altered
    the meaning of the SIP by making the defense potentially applicable to citizen
    and EPA enforcement actions, thereby limiting injunctive relief available under
    the Act and delaying the enforcement of excess emission violations.
    Environmental Petitioners identify a statement by the TCEQ that “its rules are
    not intended to nor do they impact citizens’ legal rights under the [CAA].” 30
    Tex. Reg. at 8922.
    Environmental Petitioners are correct that, in partially approving a SIP,
    the EPA may not “overid[e] state policy,” Bethlehem, 742 F.2d at 1036-37, and
    alter the meaning of the SIP. In its partial approval of the SIP revision,
    however, the EPA reasoned as follows: “[A]pproval of the provisions in sections
    101.222(b), (c), (d), and (e) into the Texas SIP does not preclude citizen suits
    under the Act. Rather, the affirmative defense may be raised in defense of a
    claim brought by EPA, the State or a private citizen.” 75 Fed. Reg. at 68,999.
    The EPA went on to state that “even where an affirmative defense is successfully
    raised in defense to an action for penalties, it does not preclude other judicial
    relief that may be available, such as injunctive relief or a requirement to
    mitigate past harm or to correct the non-compliance at issue.” Id.
    The above-mentioned reasoning provided by the EPA supports its position
    that it did not alter the meaning of the SIP or broaden its application beyond
    what Texas intended in its partial approval of the plan. We therefore reject
    Environmental Petitioners’ argument.
    19
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    B. Arguments Raised By Industry Petitioners
    Industry Petitioners argue that the portion of the SIP revision containing
    the affirmative defense for planned SSM activity fully complies with the CAA
    and should have been approved by the EPA and that the EPA’s disapproval was
    contrary to law. They further argue that the EPA’s decision was arbitrary and
    capricious. In the alternative, Industry Petitioners argue that the EPA should
    have severed and approved the affirmative defense for planned startup and
    shutdown activity, even if it disapproved the affirmative defense for planned
    maintenance activity. Industry Petitioners also request that approval of the SIP
    be backdated to June 30, 2006, so as to eliminate any gap between the expiration
    of the previous affirmative defense and the current affirmative defense.
    1. Compliance with the CAA
    The EPA’s decision partially disapproving the SIP revision containing an
    affirmative defense for planned SSM activity is invalid if it is found by this court
    to be, inter alia, “not in accordance with law.” 
    5 U.S.C. § 706
    (2)(A). The Act
    provides that the EPA “shall not approve a revision of a plan if the revision
    would interfere with any applicable requirement concerning attainment” of
    NAAQS or “or any other applicable requirement” of the Act. See 
    42 U.S.C. § 7410
    (l).
    The EPA interprets section 7413 of the Act as only authorizing affirmative
    defenses that are narrowly tailored to address periods of unavoidable, excess
    emissions during certain SSM activity, “where it is infeasible to meet the
    applicable limit.” Consequently, the agency concludes that section 7413 does not
    authorize an affirmative defense for planned SSM activity. Accordingly, this
    court must determine if the EPA’s interpretation of section 7413 is entitled to
    Chevron deference. Chevron, 
    467 U.S. at 843
    . We hold that it is.
    As stated, the EPA’s procedure of “notice-and-comment rulemaking” and
    “adjudication” is generally a sufficiently formal and deliberative process. Mead
    20
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    Corp., 
    533 U.S. at 229-30
    . Therefore, “[t]he court applies the two-step Chevron
    analysis to questions involving the EPA’s interpretation of the statutes it
    administers.” Chevron, 
    467 U.S. at 842-43
    . “If Congress ‘has directly spoken to
    the precise question at issue,’ the agency and the court ‘must give effect to the
    unambiguously expressed intent of Congress.’” 
    Id.
     If the statute, however, is
    “silent or ambiguous with respect to the specific issue,” the court must assess
    whether the agency’s interpretation of the Act is “based on a permissible
    construction of the statute” and, therefore, entitled to Chevron deference.
    Chevron, 
    467 U.S. at 843
    .
    Thus, under Chevron step one, we begin by looking at whether the statute
    is silent or ambiguous with regard to the specific issue in dispute. Here, section
    7413 does not discuss whether a state may include in its SIP the availability of
    an affirmative defense against civil penalties for planned SSM activity. 
    42 U.S.C. § 7413
    . Accordingly, we turn to step two of Chevron and ask whether the
    EPA’s interpretation of section 7413, as not authorizing an affirmative defense
    against civil penalties for planned SSM activity, is entitled to deference.
    Chevron, 
    467 U.S. at 843
    .
    As stated, relying on the definition of “emission limitation” found in
    section 302(k) of the Act, the EPA submits that its “interpretation of the CAA is
    that it is not appropriate for SIPs to exempt periods of startup, shutdown,
    maintenance or malfunction from compliance with applicable emission limits.”
    75 Fed. Reg. at 68,991-92; 
    42 U.S.C. § 7602
    (k).
    Citing its authority to assess civil penalties under section 7413 of the Act,
    the agency reasons that an effective enforcement program must be able to collect
    penalties to deter avoidable violations. 
    42 U.S.C. § 7413
    . Further, while the
    EPA acknowledges that “sources may, despite good practices, be unable to meet
    emission limitations” during certain SSM activity, the EPA’s interpretation of
    section 7413 only allows sources to assert an affirmative defense for periods of
    21
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    unavoidable, excess emissions “where it is infeasible to meet the applicable
    limit.” Id. at 68,992. For this reason, a SIP “should only provide [an affirmative
    defense against civil penalties] for circumstances where it is infeasible to meet
    the applicable limit and the criteria that the source must prove should ensure
    that the source has made all reasonable efforts to comply.” Id. at 68,992-93; 
    42 U.S.C. § 7413
    . Consequently, the agency reasons that an appropriately crafted
    affirmative defense is one that is narrowly tailored to address unavoidable,
    excess emissions.
    The EPA submits that the portion of the SIP revision providing an
    affirmative defense for planned SSM activity is inconsistent with section 7413
    of the Act because it is not narrowly tailored to address unavoidable, excess
    emissions. Id. at 68,992. The agency supports this position by submitting that
    it does not “believe that it is infeasible for sources to meet applicable limits
    during planned maintenance” activities. Id. at 68,993. The agency reasons that
    because planned maintenance activities are predictable, a source can avoid
    excess emissions from these activities by scheduling maintenance during
    shutdown periods. Id. at 68,992. Consequently, the agency concludes that the
    affirmative defense for planned SSM activity is inconsistent with section 7413
    of the Act. We hold this to be a permissible interpretation of section 7413 of the
    Act, warranting deference.     Chevron, 
    467 U.S. at 843
    ; 
    42 U.S.C. § 7413
    .
    Accordingly, the EPA did not act contrary to law when its based its partial
    disapproval of the plan on this construction. 
    5 U.S.C. § 706
    (2)(A).
    2. Arbitrary and Capricious
    Industry Petitioners submit several arguments in support of their
    assertion that the EPA’s partial disapproval of the SIP revision was arbitrary
    and capricious. We address each of these in turn.
    As previously stated, the EPA’s decision is not valid if found by this court
    to be arbitrary or capricious. 
    5 U.S.C. § 706
    (2)(A). On the other hand, “[i]f the
    22
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    agency’s reasons and policy choices conform to minimal standards of rationality,
    then its actions are reasonable and must be upheld.” Tex. Oil & Gas Ass’n, 
    161 F.3d at 934
    .
    Citing GHASP v. U.S. E.P.A., 289 F. App’x 745 (5th Cir. 2008), Industry
    Petitioners argue that the EPA must approve any SIP revision that is more
    stringent than the preexisting SIP. In 2000, the EPA approved a Texas excess
    emissions rule that included an exemption for emissions from planned
    maintenance. See 
    65 Fed. Reg. 70,792
     (Nov. 28, 2000); 
    25 Tex. Reg. 6727
    -6751
    (July 14, 2000). In its brief, however, the EPA points out that it has publicly
    conceded that its approval of the Texas 2000 rule was erroneous.11 It is the
    agency’s position that it should not be required to make the same mistake twice
    for the sole purposes of consistency.
    An agency is not bound to follow a prior, incorrect interpretation of its own
    policy.    Bowles v. Seminole Rock & Sand Co., 
    325 U.S. 410
    , 414 (1945).
    Moreover, an agency is permitted to change its policy interpretations. FCC v.
    Fox Tele. Stations, Inc., 
    556 U.S. 502
    , 514-15 (2009); National Cable &
    Telecommunications Ass’n v. Brand X Internet Services, 
    545 U.S. 967
    , 981 (2005).
    Consequently, we hold that the EPA’s previous, admittedly erroneous, approval
    of a prior Texas SIP provision, does not mandate its approval of the current SIP
    revision at issue, simply because it is more stringent than the provision
    previously approved in error.
    Industry Petitioners next argue that the EPA, in partially disapproving
    the SIP revision, impermissibly made the SIP more stringent than what Texas
    had intended, i.e., a SIP without any accommodation for planned SSM emissions.
    We disagree.
    11
    Technical Support Document for 30 Tex. Admin. Code Chapter 101, General Air
    Quality Rules, Rule Log Numbers 2001-075-101-AI & 2003-038-101-AI (March 2, 2004).
    23
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    The EPA may approve or disapprove a provision in a SIP, but may not
    require a state to add any provision to its proposal. See Fla. Power & Light Co.,
    
    650 F.2d at 587-89
    . Further, the EPA may not exercise its power to partially
    approve and disapprove portions of a SIP to make it more stringent than
    intended by the state. See Bethlehem Steel, 742 F.2d at 1034-35.
    In its partial disapproval of the SIP, the EPA noted the following:
    The provisions being disapproved address completely
    separate activities . . . (planned activities) from those
    addressed by the provisions being approved (unplanned
    activities). The approved provisions will provide the
    exact limited relief intended by the State for sources
    covered by those provisions . . . . EPA's action
    disapproving similar relief for excess emissions during
    planned activities does not affect the stringency of the
    defense being approved for periods of excess emissions
    during unplanned activities.
    75 Fed. Reg. at 68,993. This reasoning supports the EPA’s position that its
    partial disapproval of the SIP did not make the remaining approved portions
    more stringent than what Texas had intended.
    Industry Petitioners next argue that the EPA’s partial disapproval of the
    SIP revision was in error because the agency never established that the
    affirmative defense for planned SSM activity “would interfere” with NAAQS
    attainment. 
    42 U.S.C. § 7410
    (l).
    With respect to this issue, the EPA stated that it does not interpret the Act
    as requiring it to demonstrate that there will be a violation of NAAQS if it
    disapproves a SIP revision. 75 Fed. Reg. at 68,994. The agency further noted
    that “the language in section 110(l) provides that EPA must disapprove a SIP
    revision if it ‘would interfere with any applicable requirement concerning
    attainment.’ This is quite distinct from an obligation to prove that a violation
    will occur.” Id.
    24
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    We agree with the EPA’s position that it is not required by the Act to prove
    that a violation will occur as a prerequisite to disapproving the plan. However,
    in disapproving a plan, the agency is required to provide reasoning supporting
    its conclusion that the disapproved provision would interfere with an applicable
    requirement of the Act. 
    42 U.S.C. § 7410
    (l). As stated, the agency has provided
    sufficient reasoning supporting its conclusion that the affirmative defense for
    planned SSM activity was inconsistent with section 7413 of the Act because it
    was not narrowly tailored to address unavoidable, excess emissions because it
    provided a defense for SSM activities during which excess emissions could be
    avoided.   Consistent with our previous holding that this conclusion is a
    permissible construction of the statute that is not contrary to law, we hold the
    same conclusion to be a sufficient basis for the agency’s partial disapproval of the
    plan pursuant to sections 7413 and 7410(l). 
    42 U.S.C. §§ 7413
    , 7410(l)
    Industry Petitioners also argue that the EPA was required to approve the
    affirmative defense scheme as a necessary step to Texas’s transition to a
    permitting scheme. In support of their argument, Industry Petitioners point to
    the doctrines of “administrative necessity” and “one-step-at-a-time.” See Ala.
    Power Co. v. Costle, 
    636 F.2d 323
    , 357-60 (D.C. Cir. 1979); U.S. Brewers Ass’n,
    Inc. v. EPA, 
    600 F.2d 974
    , 982 (D.C. Cir. 1979). With respect to this issue, the
    EPA provided the following response:
    [T]he State's submitted phased-in permitting process
    will not serve to modify any applicable requirement
    under the Texas SIP. Furthermore, our action
    disapproving the three provisions at issue . . . merely
    maintains the status quo and should have no effect on
    that permitting process.
    ....
    [S]ources have been obligated to comply at all times
    with the applicable emission limits with no enforcement
    discretion or affirmative defense provisions since the
    previous Texas rules expired from the Texas SIP on
    25
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    June 30, 2006 by their own terms. Thus there is no
    administrative necessity or “one step at a time”
    argument applicable in this situation.
    75 Fed. Reg. at 69,899-900. This reasoning supports the EPA’s position that it
    was not required to approve the provision containing an affirmative defense for
    planned SSM activity in light of Texas’s transition to a permitting scheme.
    Consequently, we hold that the EPA did not act arbitrarily or capriciously
    in its disapproval of the portion of the SIP revision containing an affirmative
    defense for planned SSM activity. The above-mentioned reasons provided by the
    EPA for disapproving the provision “conform to minimal standards of
    rationality”; therefore, they are reasonable and will be upheld by this court. Tex.
    Oil & Gas Ass’n, 
    161 F.3d at 934
    .
    3. Severability of planned startup and shutdown activity
    The EPA has determined that the provisions relating to planned startup
    and shutdown activities are not severable from the planned maintenance
    provisions. 
    75 Fed. Reg. 68,991
    , 68,997. Industry Petitioners argue that the
    EPA should have severed and approved the affirmative defense for planned
    startup and shutdown activity, even if it had determined that there should be
    no affirmative defense for planned maintenance activity. We disagree.
    We decline to address the issue of whether the EPA was correct in
    concluding that the provisions relating to planned startup and shutdown
    activities are not severable from the planned maintenance provisions because,
    even if severed, the provisions would not have been consistent with the agency’s
    interpretation of section 7413 of the Act. For the same reasons provided in our
    discussion above upholding the EPA’s disapproval of the affirmative defense for
    planned maintenance activity contained in 101.222(h), we uphold the EPA’s
    disapproval of the affirmative defense as it applies to planned startup and
    shutdown activity. The portion of the SIP revision providing an affirmative
    defense for planned SSM activity is inconsistent with section 7413 of the Act
    26
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    because it is not narrowly tailored to address unavoidable, excess emissions
    because it provided a defense for SSM activities during which excess emissions
    could be avoided. Id. at 68,992. Consequently, we hold that the EPA was not
    arbitrary or capricious, or contrary to law, in disapproving the provision as a
    whole.
    4. Backdating approval of the SIP
    In their final argument, Industry Petitioners request that approval of the
    SIP be backdated to June 30, 2006. In light of our conclusion that the EPA was
    not arbitrary, capricious, or contrary to law, when it disapproved the portion of
    the SIP revision containing an affirmative defense for planned SSM activity, we
    pretermit discussion of this issue.
    IV. CONCLUSION
    For these foregoing reasons, we conclude that the EPA did not act
    arbitrarily or capriciously, contrary to law, or in excess of its statutory authority,
    in its partial approval and partial disapproval of Texas’s SIP revision. We
    therefore deny the petitions for review submitted by both Environmental
    Petitioners and Industry Petitioners.
    PETITIONS DENIED.
    27