Arizona Ex Rel. Henry Darwin v. Usepa ( 2016 )


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  •                 FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    STATE OF ARIZONA, EX REL. HENRY        No. 13-70366
    R. DARWIN, Director, Arizona
    Department of Environmental
    Quality,
    Petitioner,
    v.
    U.S. ENVIRONMENTAL PROTECTION
    AGENCY; LISA P. JACKSON,
    Administrator, United States
    Environmental Protection Agency,
    Respondents,
    NATIONAL PARKS CONSERVATION
    ASSOCIATION; SIERRA CLUB,
    Respondent-Intervenor.
    2        ARIZONA EX REL. DARWIN V. USEPA
    SALT RIVER PROJECT                       No. 13-70410
    AGRICULTURAL IMPROVEMENT AND
    POWER DISTRICT,                           OPINION
    Petitioner,
    v.
    U.S. ENVIRONMENTAL PROTECTION
    AGENCY,
    Respondent,
    NATIONAL PARKS CONSERVATION
    ASSOCIATION; SIERRA CLUB,
    Respondent-Intervenors.
    On Petition for Review of an Order of the
    Environmental Protection Agency
    Argued and Submitted
    March 9, 2015—San Francisco, California
    Filed February 24, 2016
    Before: Marsha S. Berzon, Jay S. Bybee,
    and John B. Owens, Circuit Judges.
    Opinion by Judge Berzon
    ARIZONA EX REL. DARWIN V. USEPA                          3
    SUMMARY*
    Environmental Law
    The panel denied consolidated petitions for review of a
    Final Rule, promulgated by the Environmental Protection
    Agency under the Clean Air Act, that partially disapproved
    Arizona’s regional haze State Implementation Plan (“SIP”) –
    setting forth emission limits and other measures – and issued
    a Federal Implementation Plan (“FIP”) in place of the
    disapproved SIP elements.
    The panel held that the EPA did not act arbitrarily and
    capriciously when it disapproved in part the SIP’s “best
    available retrofit technology” for the Coronado Generating
    Station, a coal-fueled power plant located in Eastern Arizona,
    and when it issued a replacement FIP as to the disapproved
    portions. The panel also held that the EPA did not err
    procedurally in promulgating the FIP in the same rule as its
    partial disapproval of the SIP.
    The panel held that its ultimate review of the EPA’s FIP
    must await the EPA’s final action on its proposal to revise the
    FIP in specific respects. Accordingly, the panel stayed the
    proceedings as to evaluation of the FIP’s technical feasibility
    until the administrative process was complete.
    *
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    4          ARIZONA EX REL. DARWIN V. USEPA
    COUNSEL
    Peter Glaser (argued), Troutman Sanders LLP, Washington,
    D.C.; Paul L. Gale, Troutman Sanders LLP, Irvine,
    California; Carroll W. McGuffey III, Troutman Sanders LLP,
    Atlanta, Georgia; Thomas C. Horne, Arizona Attorney
    General, and James T. Skardon, Assistant Attorney General,
    Phoenix, Arizona, for Petitioner State of Arizona.
    Norman W. Fichthorn (argued) and Aaron M. Flynn, Hunton
    & Williams LLP, Washington, D.C., for Petitioners Arizona
    Public Service Company and Salt River Project Agricultural
    Improvement and Power District.
    Angeline Purdy (argued), United States Department of
    Justice; Robert G. Dreher, Acting Assistant Attorney General,
    Washington, D.C., for Respondent United States
    Environmental Protection Agency.
    Michael A. Hiatt (argued), Earthjustice, Denver, Colorado;
    Suma Peesapati, Earthjustice, San Francisco, California, for
    Respondent-Intervenors National Parks Conservation
    Association and Sierra Club.
    Maureen A. Scott, Matthew Laudone, and Janice M. Alward,
    Phoenix, Arizona, for Amicus Curiae Arizona Corporation
    Commission.
    Michelle L. Wood, Phoenix, Arizona, for Amicus Curiae
    Arizona Residential Utility Consumer Office.
    Gordon A. Coffee, John M. Holloway III, and Stephanie B.
    Sebor, Winston & Strawn LLP, Washington, D.C.; Rae
    Cronmiller, Environmental Counsel, National Rural Electric
    ARIZONA EX REL. DARWIN V. USEPA                  5
    Cooperative Association, Arlington, Virginia, for Amicus
    Curiae National Rural Electric Cooperative Association.
    OPINION
    BERZON, Circuit Judge:
    Congress initially enacted the Clean Air Act (“the Act” or
    “CAA”) in 1963 to “protect and enhance the quality of the
    Nation’s air resources so as to promote the public health and
    welfare and the productive capacity of its population.”
    
    42 U.S.C. § 7401
    (b)(1). Later, in the Clean Air Act
    Amendments of 1977, Pub. L. No. 95-95, § 128, 
    91 Stat. 685
    ,
    742 (current version at 
    42 U.S.C. § 7491
    ), Section 169A was
    added “in response to a growing awareness that visibility was
    rapidly deteriorating in many places, such as wilderness areas
    and national parks.” Am. Corn Growers Ass’n v. EPA,
    
    291 F.3d 1
    , 3 (D.C. Cir. 2002) (internal quotation marks
    omitted) (quoting Chevron U.S.A., Inc. v. EPA, 
    658 F.2d 271
    ,
    272 (5th Cir. 1981)).
    To improve outdoor visibility, the Act as amended
    “invites each State to submit to EPA a ‘State Implementation
    Plan’ (‘SIP’) setting forth emission limits and other measures
    necessary to make reasonable progress toward the national
    visibility goal.” Nat’l Parks Conservation Ass’n v. EPA,
    
    788 F.3d 1134
    , 1138 (9th Cir. 2015) (“NPCA”) (citing
    
    42 U.S.C. §§ 7410
    (a), 7491(b)(2)). SIPs must include
    determinations of the “best available retrofit technology”
    (“BART”) to reduce emissions from certain major emission
    sources, including large fossil-fuel power plants. 
    42 U.S.C. § 7491
    (b)(2). If a state chooses not to submit a SIP, or if
    EPA disapproves a SIP in whole or in part, “the Act requires
    6                 ARIZONA EX REL. DARWIN V. USEPA
    EPA to produce a ‘Federal Implementation Plan’ (‘FIP’) for
    that State.” NPCA, 788 F.3d at 1138–39 (citing 
    42 U.S.C. § 7410
    (c)(1)(A)).
    Arizona and the Salt River Project Agricultural
    Improvement and Power District (“the State” and “SRP,”
    respectively, and, collectively, “Petitioners”) petition for
    review of a Final Rule (“Rule”) promulgated by EPA. The
    Rule partially disapproved Arizona’s regional haze SIP
    submission and promulgated a FIP in place of the
    disapproved SIP elements. Approval, Disapproval and
    Promulgation of Air Quality Implementation Plans, 
    77 Fed. Reg. 72,512
     (Dec. 5, 2012) (the “Final Rule”). In what
    remains of this case,1 Petitioners challenge (1) EPA’s
    disapproval of Arizona’s BART determinations, and (2) the
    FIP’s replacement determinations, concerning nitrogen oxides
    (NOX) emission limits at Coronado Generating Station
    (“Coronado”), a two-unit, 733-megawatt coal-fueled power
    plant located in Eastern Arizona.
    We conclude that EPA did not act arbitrarily and
    capriciously when it disapproved in part the SIP’s BART
    determinations for Coronado and issued a replacement FIP as
    to the disapproved portions. We therefore deny the
    consolidated petitions for review.
    1
    See infra note 6.
    ARIZONA EX REL. DARWIN V. USEPA                          7
    I. STATUTORY AND REGULATORY
    BACKGROUND
    A. The Clean Air Act’s Visibility Protections
    In enacting Section 169A2 Congress “declare[d] as a
    national goal the prevention of any future, and the remedying
    of any existing, impairment of visibility in mandatory class I
    Federal areas which impairment results from manmade air
    pollution.” § 7491(a)(1). “Class I” Federal areas include
    certain national wilderness areas and national parks. Arizona
    contains twelve Class I areas, the largest of which is Grand
    Canyon National Park.
    Section 169A seeks to reduce “regional haze,” that is,
    “visibility impairment caused by geographically dispersed
    sources emitting fine particles and their precursors into the
    air.” Am. Corn Growers, 
    291 F.3d at 3
     (internal quotation
    marks omitted). In service of this goal, Section 169A
    requires that certain sources contributing to visibility
    impairment install BART—which, again, is an acronym for
    “best available retrofit technology.”3 States must review all
    major stationary emissions sources built between 1962 and
    1977 to determine whether the source “emits any air pollutant
    2
    We use “Section 169A” to refer generically to the visibility
    amendments, but use the codified version, 
    42 U.S.C. § 7491
    , for specific
    citations.
    3
    We apologize for the extensive use of acronyms in this opinion and
    include a brief glossary at the end to aid the reader. Environmental
    litigation is awash in such alphabetical shorthand, and the “insiders”
    would not know what we meant if we used other terms. We have
    therefore decided against expanding the Federal Reporter 3d (F.3d, of
    course, another shorthand) by stubbornly spelling out each term.
    8           ARIZONA EX REL. DARWIN V. USEPA
    which may reasonably be anticipated to cause or contribute
    to any impairment of visibility in” any Class I area.
    § 7491(b)(2)(A). The states are then responsible for
    determining the appropriate BART controls for each source.
    See 
    42 U.S.C. § 7491
    (b)(2)(A), (g)(2).
    EPA reviews the states’ SIP submissions, if any, for
    consistency with the statute and regulations. See 
    42 U.S.C. § 7410
    (c)(1)(A); Oklahoma v. EPA, 
    723 F.3d 1201
    , 1204
    (10th Cir. 2013). If EPA determines that a SIP does not meet
    the Act’s requirements, the federal agency may itself
    determine BART and impose a FIP. See 
    42 U.S.C. § 7491
    (b)(2)(A). More specifically, if EPA finds that a state
    has not submitted a required SIP, determines that a submitted
    SIP is incomplete, or disapproves a SIP in whole or in part, it
    “shall promulgate a [FIP] at any time within 2 years.”
    
    42 U.S.C. § 7410
    (c)(1). EPA must promulgate a FIP “unless
    the State corrects the deficiency, and [EPA] approves the plan
    or plan revision, before [EPA] promulgates [the FIP].” 
    Id.
    When determining BART, states or EPA must consider
    five factors: “[1] the costs of compliance, [2] the energy and
    nonair quality environmental impacts of compliance, [3] any
    existing pollution control technology in use at the source, [4]
    the remaining useful life of the source, and [5] the degree of
    improvement in visibility which may reasonably be
    anticipated to result from the use of such technology.”
    
    42 U.S.C. § 7491
    (g)(2). Each source subject to the BART
    requirement must install and operate BART “as expeditiously
    as practicable but in no event later than five years after the
    date of approval of a [SIP] . . . or the date of promulgation of
    [a FIP].” 
    42 U.S.C. §§ 7491
    (g)(4).
    ARIZONA EX REL. DARWIN V. USEPA             9
    B. EPA Regional Haze Regulations
    Section 169A directed EPA to issue regulations requiring
    states with Class I areas within their borders to submit SIPs
    containing “emission limits, schedules of compliance and
    other measures as may be necessary to make reasonable
    progress toward meeting the national goal.” 
    42 U.S.C. § 7491
    (b)(2). EPA was also required to develop guidelines
    for the states “on appropriate techniques and methods for
    implementing” Section 169A. 
    Id.
     § 7491(b)(1). In 1990,
    Congress added Section 169B to expand the CAA’s focus to
    include regional haze, see 
    42 U.S.C. § 7492
    —that is,
    “visibility impairment that is caused by the emission of air
    pollutants from numerous sources located over a wide
    geographic area,” 
    40 C.F.R. § 51.301
    . “Section 169B
    requires, among other things, that EPA undertake research to
    identify ‘sources’ and ‘source regions’ of visibility
    impairment in Class I areas, consider designating transport
    commissions to study the interstate movement of pollutants,
    and establish a transport commission for the Grand Canyon
    National Park.” Am. Corn Growers, 
    291 F.3d at 4
    .
    Pursuant to Sections 169A and 169B, EPA in 1999
    promulgated regional haze regulations. 
    64 Fed. Reg. 35,714
    (July 1, 1999) (codified at 
    40 C.F.R. § 51.300
    –.309). The
    D.C. Circuit partially vacated those regulations in American
    Corn Growers Ass’n v. EPA, 
    291 F.3d at 6
    .4 Thereafter, the
    agency in 2005 promulgated new regulations, the Regional
    Haze Regulations and Guidelines for Best Available Retrofit
    Technology (BART) Determinations, 
    70 Fed. Reg. 39,104
    (July 6, 2005) (“Haze Regulations”). At the same time, EPA
    issued Guidelines to help states identify “BART-eligible”
    4
    American Corn Growers is discussed infra, at p. 21.
    10         ARIZONA EX REL. DARWIN V. USEPA
    sources and determine the appropriate BART for each source.
    
    Id. at 39,156
     (codified at 40 C.F.R. pt. 51, app. Y)
    (“Guidelines”); see also 
    42 U.S.C. § 7491
    (b).
    The Haze Regulations set a goal of achieving natural
    visibility at all Class I areas by 2064. 
    40 C.F.R. § 51.308
    .
    Toward that end, the Regulations direct states to submit SIPs
    to EPA containing “goals (expressed in deciviews) that
    provide for reasonable progress towards achieving natural
    visibility conditions.” 
    40 C.F.R. § 51.308
    (d)(1). A
    “deciview” is a measurement of visibility impairment. More
    specifically, it “is a haze index derived from calculated light
    extinction, such that uniform changes in haziness correspond
    to uniform incremental changes in perception across the
    entire range of conditions, from pristine to highly impaired.”
    
    40 C.F.R. § 51.301
    . One deciview is the minimum visibility
    impairment humans can perceive. See Guidelines at 39,120
    n.32.
    The SIP must also include, among other matters,
    “emission limitations representing BART and schedules for
    compliance with BART for each BART-eligible source that
    may reasonably be anticipated to cause or contribute to any
    impairment of visibility in any mandatory Class I Federal
    area.” 
    40 C.F.R. § 51.308
    (e). The BART requirements apply
    unless the state opts to implement an alternative emission
    control measure that provides greater progress than would be
    achieved through the installation of BART (commonly
    referred to as “better-than BART”). See 
    id.
     § 51.308(e)(2).
    BART is defined as “an emission limitation based on the
    degree of reduction achievable through the application of the
    best system of continuous emission reduction for each
    pollutant which is emitted by an existing stationary facility.”
    ARIZONA EX REL. DARWIN V. USEPA                   11
    Id. § 51.301. Three of the major pollutants that states must
    evaluate when determining whether a source causes or
    contributes to visibility impairment are sulfur dioxide
    (“SO2”), nitrogen oxides (“NOX”), and particulate matter. See
    Guidelines at 39,162. States must establish BART for each
    pollutant. Id. at 39,163.
    BART determinations for fossil-fueled power plants with
    a total generating capacity greater than 750 megawatts must
    comply with the Guidelines. 
    42 U.S.C. § 7491
    (b)(2). The
    Guidelines set forth the following five-step process:
    (1) identify all available retrofit control technologies;
    (2) eliminate technically infeasible options; (3) evaluate the
    control effectiveness of remaining control technologies;
    (4) evaluate impacts and document the results; and
    (5) evaluate the visibility impacts. Guidelines at 39,164. The
    Guidelines also provide more detailed instructions for
    performing each of these steps. 
    Id. at 39
    ,164–72. “For
    sources other than 750 MW power plants . . . States retain the
    discretion to adopt approaches that differ from the
    [G]uidelines.” Guidelines at 39,158.
    Section 309 of the Haze Regulations, 
    40 C.F.R. § 51.309
    ,
    allows certain western states to develop alternative visibility
    improvement programs, based on the recommendations of the
    Grand Canyon Visibility Transport Commission (“the
    Commission”). The Commission was created to address
    visibility impairment “for the region affecting the visibility of
    the Grand Canyon National Park.” See 
    42 U.S.C. § 7492
    (f).
    This region includes sixteen Class I areas on the Colorado
    Plateau located in Arizona, Colorado, New Mexico, and Utah.
    
    40 C.F.R. § 51.309
    (b). States within the relevant Transport
    Region—Arizona, California, Colorado, Idaho, Nevada, New
    Mexico, Oregon, Utah, and Wyoming—that submit a SIP
    12           ARIZONA EX REL. DARWIN V. USEPA
    compliant with all of the Commission’s recommendations are
    “deemed to comply with the requirements for reasonable
    progress with respect to the 16 Class I areas.” 
    Id.
    § 51.309(a). Any covered state that elects not to submit a
    Section 309 plan is “subject to the requirements of [Section
    308] in the same manner and to the same extent as any State
    not included within the Transport Region.” Id. Further, even
    if a state submits a Section 309 SIP, it must submit a Section
    308 SIP or otherwise establish “reasonable progress goals” —
    including BART determinations — for any Class I areas in
    the state not covered under Section 309. Id. § 51.309(g)(2).
    II. PROCEDURAL HISTORY
    A. The State’s SIP Submissions
    The Haze Regulations set a December 17, 2007 deadline
    for SIP submittals. 
    40 C.F.R. § 51.308
    (b). EPA issued a
    finding on January 15, 2009, that thirty-seven states,
    including Arizona, had not submitted SIPs satisfying the
    Act’s visibility requirements. Finding of Failure To Submit
    State Implementation Plans Required by the 1999 Regional
    Haze Rule, 
    74 Fed. Reg. 2,392
     (Jan. 15, 2009). Noting that
    Arizona had “opted to develop [its SIP] based on the
    recommendations of the Grand Canyon Visibility Transport
    Commission” pursuant to Section 309, 
    id. at 2,393
    , EPA
    found that the State had failed to “submit the plan elements
    required by” two provisions of the Section 309 regulations,
    
    40 C.F.R. §§ 51.309
    (d)(4) and 51.309(g).5 
    Id.
     EPA further
    5
    Arizona’s Section 309 SIP, which Arizona submitted to EPA on
    December 23, 2003, and supplemented a year later, merits further
    explanation. EPA did not act upon the State’s 2003 and 2004
    submissions. The Section 309 regulations were revised in October 2006,
    ARIZONA EX REL. DARWIN V. USEPA                          13
    explained that “[t]his finding starts the two year clock for the
    promulgation by EPA of a FIP.” 
    Id.
    Although EPA determined that its January 2009 finding
    triggered the Act’s two-year window, see 
    42 U.S.C. § 7410
    (c)(1), it did not take any further action by January
    2011. Several environmental groups sued EPA in early 2011
    to compel the agency to promulgate FIPs for the states
    covered by the January 2009 finding. See Nat’l Parks
    Conservation Ass’n v. EPA, No. 11-CV-01548 (D.D.C.).
    EPA and the plaintiff groups entered into a Consent Decree
    setting deadlines for EPA action for each state covered by the
    following the D.C. Circuit’s decision in Center for Energy and Economic
    Development v. EPA, 
    398 F.3d 653
     (D.C. Cir. 2005). See 
    71 Fed. Reg. 60,612
     (Oct. 13, 2006). Arizona then resubmitted its Section 309 SIP to
    EPA in December 2008, acknowledging that the plan did not include
    provisions required under 
    40 C.F.R. §§ 51.309
    (d)(4) and 51.309(g) as
    revised. In 2013, EPA disapproved the Section 309 SIP because of these
    deficiencies. 
    78 Fed. Reg. 48,326
     (Aug. 8, 2013).
    Arizona contends that, as EPA did not expressly find that its Section
    309 SIP was incomplete within six months of its initial submission in
    2003, the plan became complete by operation of law. Thus, it contends,
    
    42 U.S.C. § 7410
    (k)(2) required EPA to disapprove its SIP within one
    year, which, of course, it did not do. But, as EPA noted in its 2013
    disapproval, the fact that Arizona’s submission met the completeness
    criteria set out in § 7410(k) “[did] not mean that [it was] complete in the
    sense that [it] contained the provisions necessary to satisfy the
    requirements of [Section 309].” 78 Fed. Reg. at 48,327. The § 7410(k)
    criteria “do not include the substantive provisions that a given SIP must
    include to comply with the minimum requirements of the [Act].” Id.
    Those provisions are instead “set out in the [Act] itself and in EPA’s
    implementing regulations.” Id. EPA concluded that it could not approve
    Arizona’s previously submitted SIP until it was resubmitted with valid
    provisions for addressing stationary sources, provisions Arizona has
    conceded were not included in the 2003 plan. Id.
    14           ARIZONA EX REL. DARWIN V. USEPA
    lawsuit. For Arizona, the Consent Decree required EPA by
    November 15, 2012 either to approve the State’s SIP with
    respect to its BART determinations or to propose a FIP.
    To avoid a FIP, Arizona elected to develop a Section 308
    SIP; it was submitted to EPA on February 28, 2011. The SIP
    proposed progress goals and long term strategies to achieve
    those goals, including BART determinations. Specifically,
    the SIP included BART determinations for emission units at
    three fossil fuel power plants that Arizona concluded were
    BART-eligible and subject to BART: Apache Generating
    Station Units 1–3, Cholla Power Plant Units 2–4, and
    Coronado Generating Station Units 1–2. Only the SIP’s
    determinations as to Coronado are at issue in this case.6
    Overall, the State’s BART determinations for NOX, the
    pollutant with which we are concerned here, consisted of
    “combustion controls, either in the form of low-NOX burners
    (LNB) with flue gas recirculation (FGR), or LNB with
    overfire air (OFA) or separated overfire air (SOFA).” 
    77 Fed. Reg. 42,834
    , 42,842 (July 20, 2012). For Coronado, Arizona
    6
    The State and other industry petitioners (Arizona Electric Power
    Cooperative, Arizona Public Service Company, and PacifiCorp) initially
    filed petitions for review of the Final Rule’s determinations as to Apache
    and Cholla, and we consolidated our review of those petitions with this
    case. On February 20, 2015, we ordered the litigation with respect to
    Cholla severed and held in abeyance pending completion of state and
    federal administrative proceedings that could render the petitions for
    review moot. As of the publication of this opinion, those proceedings
    have not yet been completed. On June 17, 2015, we dismissed the
    petitions as to Apache after EPA issued a final action approving a source-
    specific revision to the SIP that established a BART alternative for
    Apache and withdrawing the portions of the FIP addressing BART for
    Apache. See Approval and Promulgation of Air Quality Implementation
    Plans, 
    80 Fed. Reg. 19,220
     (Apr. 10, 2015).
    ARIZONA EX REL. DARWIN V. USEPA                        15
    determined that the proper control technology was low-NOX
    burners with overfire air. Translating the chosen technology
    into the resulting emission improvement, the SIP established
    enforceable NOX emissions limits of 0.32 lb/mmBtu for both
    units of the Coronado facility.7
    B. EPA’s Actions
    In July 2012, EPA proposed (1) partially to approve and
    partially to disapprove the State’s BART determinations with
    respect to the three power plants in its Section 308 SIP; and
    (2) to promulgate a FIP for the disapproved elements.
    77 Fed. Reg. at 42,834. EPA deferred taking action “on the
    State’s other BART determinations or any other parts of the
    SIP regarding the remaining requirements of the [Haze
    Regulations].” Id. at 42,836. In a later rulemaking, EPA
    approved in part and disapproved in part the remaining
    portions of Arizona’s Section 308 SIP. See 
    78 Fed. Reg. 46,142
     (July 30, 2013) (“Phase 2 Rule”).8 After a notice-and-
    comment period, EPA promulgated the Final Rule challenged
    here, in December 2012. 77 Fed. Reg. at 72,512.
    The Final Rule approved the State’s emission limits for
    SO2 and particulate matter at all the units but disapproved the
    State’s emissions limits for NOX at the seven coal-fired
    7
    The SIP also included BART determinations for SO2 and particulate-
    matter, but they are not at issue in this case.
    8
    Petitioners petition for review of the Phase 2 Rule in Phoenix Cement
    Co. v. EPA, No. 13-73383, decided contemporaneously with this case in
    a memorandum disposition.
    16           ARIZONA EX REL. DARWIN V. USEPA
    generating units at Apache, Cholla, and Coronado.9 Id. at
    72,514. EPA explained that Arizona’s “overall approach” to
    the five-step BART analysis was “generally reasonable and
    consistent with the [Haze Regulations] and the BART
    Guidelines.” 77 Fed. Reg. at 42,840. But it determined that
    Arizona’s BART analysis suffered from several flaws,
    particularly with respect to costs and visibility improvement,
    that resulted in NOX control determinations “inconsistent”
    with the Haze Regulations. 77 Fed. Reg. at 42,841–42; see
    also 77 Fed. Reg. at 72,516–21. EPA found that the State’s
    analyses with respect to SO2 and particulate matter suffered
    from similar “deficiencies,” 77 Fed. Reg. at 72,517, but
    nonetheless approved Arizona’s determinations for these
    pollutants because the analytical flaws had no “substantive
    impact on [the State’s] selection of controls.” 77 Fed. Reg.
    at 42,841.
    Explaining that the Consent Decree required EPA
    promptly to issue a FIP for any portion of the Arizona SIP it
    disapproved, the Final Rule simultaneously issued a FIP
    addressing the disapproved elements. 77 Fed. Reg. at
    72,567–68. EPA conducted a “new five-factor BART
    analysis” of the three power plants to evaluate Arizona’s SIP
    and “to document the technical basis for proposing BART
    determinations in [EPA’s] FIP,” focusing in particular on
    analyzing the cost controls and visibility impacts associated
    with the different BART options. 77 Fed. Reg. at 42,852; see
    generally 77 Fed. Reg. at 42,852–65; 77 Fed. Reg. at
    72,526–61.
    9
    EPA approved Arizona’s BART determination for the natural gas-fired
    Apache Unit 1. See 77 Fed. Reg. at 72,514.
    ARIZONA EX REL. DARWIN V. USEPA                      17
    Based on these analyses, EPA concluded that selective
    catalytic reduction (“SCR”) with low-NOX burners and
    overfire air — the most stringent available retrofit control
    option — was the proper BART control for Coronado. See
    77 Fed. Reg. at 42,864. EPA proposed NOX emission limits
    much lower than those contained in Arizona’s SIP: 0.050
    lb/mmBtu (calculated on a rolling 30-boiler-operating-day
    average) for Coronado Unit 1, and 0.080 lb/mmBtu for
    Coronado Unit 2.10 Id. at 42,865, tbl. 24. EPA also proposed
    compliance deadlines, as well as recordkeeping and reporting
    requirements, to enforce the FIP’s BART determinations.11
    Id. Finally, EPA sought public comment on several aspects
    of the proposed FIP. Id. at 42,835–36.
    In the Final Rule, EPA revised certain elements of the
    proposed FIP in response to public comments and additional
    information. 77 Fed. Reg. at 72,514. Notably, EPA
    weakened the final NOX emissions limits to “provide an extra
    margin of compliance” and changed its methodology to
    require plant-wide averaging. Id. at 72,514–15. As relevant
    here, EPA changed its proposed NOX emission limits from
    0.050 lb/mmBtu for Coronado Unit 1 and 0.080 lb/mmBtu for
    Coronado Unit 2 to an averaged limit of 0.065 lb/mmBtu
    across both units of the Coronado facility. Id. at 72,514–15,
    tbl. 1. The Final Rule also extended the compliance deadlines
    for installation and operation of the controls at the facilities.
    See id.
    10
    Arizona’s SIP had adopted NOX emissions limits of 0.32 lb/mmBtu
    for both units of the Coronado facility.
    11
    Arizona’s SIP was disapproved in part because it lacked such
    deadlines and requirements. See 77 Fed. Reg. at 72,514.
    18          ARIZONA EX REL. DARWIN V. USEPA
    Arizona and SRP filed timely petitions for review of the
    Final Rule. After the cases were consolidated, we permitted
    National Parks Conservation Association and Sierra Club (the
    “Respondent-Intervenors”) to intervene in the consolidated
    action.
    III. DISCUSSION
    A. Standard of Review
    Under the Administrative Procedure Act (“APA”), we
    uphold a final agency action unless it is “arbitrary, capricious,
    an abuse of discretion, or otherwise not in accordance with
    law.” 
    5 U.S.C. § 706
    (2). To meet its regulatory obligations,
    an agency must “examine the relevant data and articulate a
    satisfactory explanation for its action including a rational
    connection between the facts found and the choice made.”
    Motor Vehicle Mfrs. Ass’n of U.S., Inc. v. State Farm Mut.
    Auto. Ins. Co., 
    463 U.S. 29
    , 43 (1983) (internal quotation
    marks and citation omitted). An agency’s action is “arbitrary
    and capricious” within the meaning of APA § 706(2) “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.” Id. “When we
    review an agency action ‘involv[ing] primarily issues of fact,’
    and where ‘analysis of the relevant documents requires a high
    level of technical expertise, we must defer to the informed
    discretion of the responsible federal agencies.’” NPCA,
    788 F.3d at 1141 (quoting Marsh v. Or. Nat. Res. Council,
    
    490 U.S. 360
    , 377 (1989)).
    ARIZONA EX REL. DARWIN V. USEPA                  19
    The parties vigorously dispute how we should apply the
    APA arbitrary and capricious standard here. EPA maintains
    that in this case, as in most administrative law cases, the
    standard calls for judicial deference to the federal agency as
    to the decisions within its authority. Arizona (with the
    support of SRP) contends, to the contrary, that Section
    169A’s allocation of initial BART authority to the states
    requires that we defer to “the state’s expert judgments, not to
    EPA’s.” As this brief summary indicates, the parties’
    disagreement concerning judicial review is grounded in
    competing visions of the Act’s division of responsibility
    between the states and EPA. We therefore begin our analysis
    at the agency level, progressing thereafter to the question of
    our review standard.
    The states possess “broad authority over BART
    determinations. . . . Congress intended the states to decide
    which sources impair visibility and what BART controls
    should apply to those sources.” Am. Corn Growers, 
    291 F.3d at 8
    . In this connection, Section 169A of the Act gives states
    the initial responsibilities of determining which sources are
    subject to BART and of deciding, based on consideration of
    the five statutory factors, what BART controls must be
    installed and what the resulting emission limitations should
    be. See 
    42 U.S.C. § 7491
    (b)(2)(A), (g)(2).
    But, as the Tenth Circuit has noted, the BART
    determination process “does not differ from other parts of the
    [Act]—states have the ability to create SIPs, but they are
    subject to EPA review.” Oklahoma, 723 F.3d at 1209; see
    also N. Dakota v. EPA, 
    730 F.3d 750
    , 758 (8th Cir. 2013).
    EPA may only approve SIPs, or portions of SIPs, that “meet[]
    all the applicable requirements” of the Act. 
    42 U.S.C. § 7410
    (k)(3). Thus, while the Act “gives states discretion in
    20          ARIZONA EX REL. DARWIN V. USEPA
    balancing the five BART factors, it also mandates that the
    state adhere to certain requirements when conducting a
    BART analysis.”          Oklahoma, 723 F.3d at 1208.
    Consequently, when reviewing regional haze SIPs, EPA may
    not approve “a BART determination that is based upon an
    analysis that is neither reasoned nor moored to the [Act]’s
    provisions.” N. Dakota, 730 F.3d at 761. In short, EPA is not
    limited to the “ministerial” role of verifying whether a
    determination was made; it must “review the substantive
    content of the BART determination.” Id.
    Alaska Department of Environmental Conservation v.
    EPA, 
    540 U.S. 461
     (2004) (“ADEC”), does not support the
    opposite conclusion, Arizona’s contention to the contrary
    notwithstanding. ADEC involved a challenge to EPA’s
    authority to review states’ determinations of “best available
    control technology” (“BACT”) under the Prevention of
    Significant Deterioration program (“PSD”), 
    42 U.S.C. § 7470
    et seq., a different part of the Act from the one mandating
    BART. See ADEC, 
    540 U.S. at 468
    . The PSD program is
    applicable to new construction of pollution emitting facilities.
    See 
    42 U.S.C. § 7475
    . As with the BART process at issue
    here, for the PSD program the state “exercises primary or
    initial responsibility for identifying BACT in line with the
    Act[].” ADEC, 
    540 U.S. at 484
    .
    ADEC rejected an argument made by the petitioners in
    that case similar to Arizona’s contention here—in that
    instance, that EPA’s enforcement role was limited to ensuring
    that the state-issued PSD permit contain a BACT
    requirement. Instead, ADEC accepted EPA’s interpretation
    of its authority—that EPA is authorized to review state
    BACT determinations to ensure they are “reasonably moored
    to the Act’s provisions.” 
    Id. at 485
    , 488–89.
    ARIZONA EX REL. DARWIN V. USEPA                  21
    To be sure, ADEC explained, Alaska had “considerable
    leeway” in its BACT determinations, and EPA was required
    to accord appropriate deference to such determinations. 
    Id. at 490
    . But EPA has the authority to verify “substantive
    compliance” with the Act’s BACT provisions “to guard
    against unreasonable designations.” 
    Id.
     at 489–90. ADEC is
    thus fully consistent with our conclusion that EPA has
    substantive authority to assure that a state’s proposals comply
    with the Act, not simply the ministerial authority to assure
    that the state has made some determination of BART.
    Arizona also invokes American Corn Growers, in which
    petitioners challenged aspects of EPA’s initial 1999 regional
    haze rule. That case does not support Arizona’s position
    regarding EPA’s SIP role either. The D.C. Circuit in
    American Corn Growers disapproved EPA’s initial rule in
    part because its requirements were “inconsistent with the
    Act’s provisions giving the states broad authority over BART
    determinations.” Am. Corn Growers, 
    291 F.3d at 8
    . But
    American Corn Growers in no way suggested that once a
    state has exercised its BART role by proposing a SIP, EPA
    lacks authority substantively to review the SIP for
    consistency with the Act.
    From our determination that EPA has a substantive role
    in deciding whether state SIPs are compliant with the Act and
    its implementing regulations follows the conclusion that the
    ordinary APA “arbitrary and capricious” judicial review
    standard applies, with the requisite deference, to EPA’s
    determinations. Again, neither American Corn Growers nor
    ADEC supports a contrary conclusion. In particular, neither
    ADEC nor American Corn Growers bolsters Arizona’s
    contention that, upon judicial review, EPA bears the burden
    22          ARIZONA EX REL. DARWIN V. USEPA
    of proving that the State’s BART determinations are
    unreasonable.
    ADEC did state that, for the purposes of deciding whether
    the state agency’s BACT determination in that case was
    reasonable, “the production and persuasion burdens remain
    with EPA.” 
    540 U.S. at 494
    . But ADEC was at that juncture
    addressing a concern wholly absent here. In ADEC, the
    Supreme Court held that the Act prevented EPA from
    “gain[ing] a proof-related tactical advantage” by imposing a
    stop-construction order rather than filing a civil action in state
    court. 
    540 U.S. at
    493–94. In that connection, ADEC noted
    that “Congress nowhere suggested that the allocation of proof
    burdens would differ depending upon which enforcement
    route EPA selected.” 
    Id. at 493
     (emphasis added).
    Petitioners in this case, however, challenge not an EPA
    enforcement action but the Final Rule disapproving in part
    Arizona’s SIP submission. Such prospective administrative
    agency rulemaking is ordinarily reviewed under the APA’s
    arbitrary and capricious standard; there is no basis for
    applying a different standard here.
    In sum, Section 169A gives states substantial
    responsibility in determining appropriate BART controls.
    EPA may not disapprove reasonable state determinations that
    comply with the relevant statutory and regulatory
    requirements. See Am. Corn Growers, 
    291 F.3d at
    6–8. That
    is, as ADEC put it, EPA may not “second guess” reasoned,
    legally compliant state decisions. 
    540 U.S. at 490
    . But
    Congress intended that EPA, not the states alone, ultimately
    ensure that state determinations as to regional haze comply
    with the Act, and so authorized EPA to disapprove state
    “analysis that is neither reasoned nor moored to the [Act’s]
    provisions.” N. Dakota, 730 F.3d at 761. Once the federal
    ARIZONA EX REL. DARWIN V. USEPA                  23
    agency has done so, our role as the reviewing court remains
    what it always is when substantively reviewing agency action
    under the APA—deciding, with appropriate deference to the
    federal agency, whether the agency’s action was “arbitrary,
    capricious, an abuse of discretion, or otherwise not in
    accordance with law.” 
    5 U.S.C. § 706
    (2).
    B. Partial Disapproval           of   the    SIP’s     BART
    Determinations
    We now turn to Petitioners’ challenges to EPA’s partial
    disapproval of Arizona’s SIP as it applies to the Coronado
    BART determinations.
    1. Arizona’s procedural claim
    Before addressing Petitioners’ substantive arguments, we
    address Arizona’s procedural argument. Arizona maintains
    that, in acting only on the BART determinations when it
    promulgated the Final Rule, deferring action on the rest of the
    SIP, EPA “misconstrued its statutory authority and acted in
    an arbitrary fashion.” Specifically, Arizona contends that
    EPA cannot properly evaluate BART determinations
    separately from the broader reasonable progress analysis,
    because BART determinations are just one aspect of
    achieving Section 169A’s overall “reasonable progress” to
    the natural visibility goal. 
    42 U.S.C. § 7491
    (b)(2).
    That is not so. There is no requirement that EPA approve
    or disapprove a SIP submittal in a single action. To the
    contrary, the Act expressly permits EPA to approve or
    disapprove a SIP “in part.” 
    42 U.S.C. § 7410
    (c)(1), (k)(3);
    see also Ass’n of Irritated Residents v. EPA, 
    423 F.3d 989
    ,
    997 (9th Cir. 2005).
    24           ARIZONA EX REL. DARWIN V. USEPA
    The EPA rule partially disapproving a regional haze SIP
    which was recently upheld by Oklahoma, 723 F.3d at 1206,
    for example, “t[ook] no action on whether Oklahoma has
    satisfied the reasonable progress requirements.” 
    76 Fed. Reg. 81,728
    , 81,730 (Dec. 28, 2011). Under the Haze Regulations,
    SIPs must contain reasonable progress goals, 
    40 C.F.R. § 51.308
    (d)(1), as well as source-specific BART
    determinations, 
    id.
     § 51.308(e)(1).12       Of course, the
    implementation of the BART determinations will ultimately
    contribute toward meeting the reasonable progress goals. But
    the Act sets out standards for BART that are freestanding,
    source-by-source, and not dependent on the long term
    visibility goals identified. EPA did not act arbitrarily by
    considering Arizona’s BART determinations separately from
    the State’s reasonable progress analysis.
    2. Arizona’s substantive claims
    Turning to the substance of the Final Rule: EPA found
    that the SIP’s “overall approach” was “generally reasonable
    and consistent” with the Haze Regulations and the
    Guidelines.13 77 Fed. Reg. at 42,840. But it concluded that
    the State’s BART determinations were deficient in three
    particular respects. First, Arizona’s control cost calculations
    12
    As Arizona argues, in “some circumstances” BART controls may not
    be “necessary to make reasonable progress.” But that is so when states
    elect to implement an “emissions trading program or other alternative
    measure,” that result in “greater reasonable progress” than BART. Id.
    § 51.308(e)(2) (emphasis added). Here, the State did not submit an
    alternative measure under § 51.308(e)(2), choosing instead to conduct a
    source-specific BART analysis.
    13
    Petitioners do not challenge the Haze Regulations or the Guidelines,
    only their implementation in the Final Rule here at issue.
    ARIZONA EX REL. DARWIN V. USEPA                 25
    were not performed in accordance with the Guidelines and
    were otherwise unreasonable. See id. at 42,841; 77 Fed. Reg.
    at 72,516–18, 72,566. Second, Arizona did not properly
    evaluate the visibility improvements to all Class I areas. See
    77 Fed. Reg. at 42,841–42; 77 Fed. Reg. at 72,519, 72,566.
    And third, Arizona inadequately explained its consideration
    of the BART factors. See 77 Fed. Reg. at 42,841, 42,846; 77
    Fed. Reg. at 72,517, 72,566. Because of these deficiencies,
    EPA partially disapproved Arizona’s BART determinations,
    including those pertaining to Coronado’s NOX emission
    controls.
    Arizona and SRP contend that each of EPA’s conclusions
    is legally flawed and unsupported by the record.
    Consequently, they contend, the agency’s partial disapproval
    of the SIP was arbitrary and capricious. We disagree. EPA’s
    conclusions concerning the State’s BART analysis and
    determinations were well explicated, carefully grounded in
    the administrative record, and analytically reasonable, and so
    properly support its disapproval of Arizona’s NOX BART
    determinations for Coronado.
    (i) The SIP’s Cost Analysis
    As one of the BART factors, states must consider the
    “costs of compliance.” 
    42 U.S.C. § 7491
    (g)(2); 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A). “States have flexibility in how they
    calculate costs.” Haze Regulations, 70 Fed. Reg. at 39,127.
    A state’s cost calculations are critical to determining a BART
    control’s “cost effectiveness,” where “‘effectiveness’ is
    measured in terms of tons of pollutant emissions removed,
    and ‘cost’ is measured in terms of annualized control costs.”
    Id. at 39,167.
    26          ARIZONA EX REL. DARWIN V. USEPA
    After identifying control alternatives and achievable
    emissions performance levels, states are directed to “develop
    estimates of capital and annual costs.” Id. at 39,166. “The
    basis for equipment cost estimates also should be
    documented, either with data supplied by an equipment
    vendor . . . or by a referenced source (such as the [Office
    of Air Quality Planning and Standards] Control Cost
    Manual . . . ).” Id.
    The Guidelines instruct that the Cost Manual “addresses
    most control technologies in sufficient detail for a BART
    analysis,” and that “cost estimates should be based on the
    [Cost Manual] where possible” to “maintain and improve
    consistency.” Id. States are allowed by the Guidelines to
    include “additional information” — such as “any information
    supplied by vendors that affects your assumptions regarding
    purchased equipment costs, equipment life, [or] replacement
    of major components” — in their cost calculations, but
    require them to provide documentation for any “element of
    the calculation that differs from the . . . Cost Manual.” Id.
    n.15. Finally, the Guidelines indicate that “[t]he cost analysis
    should also take into account any site-specific design or other
    conditions . . . that affect the cost of a particular BART”
    option. Guidelines at 39,166.
    In its proposed rule, EPA found “certain aspects” of
    Arizona’s cost calculations “inconsistent” with the Guidelines
    and Cost Manual and “disagree[d] with the manner in which
    [Arizona] interpreted the cost-related information included in
    its [] SIP.” 77 Fed. Reg. at 42,841. With regard to Coronado,
    specifically, EPA noted in its proposed rule that SRP
    “provided summaries of total control costs, such as total
    annual operating and maintenance costs and total annualized
    capital cost, but did not provide cost information at a level of
    ARIZONA EX REL. DARWIN V. USEPA                  27
    detail that included line item costs.” Id. at 42,850. This
    omission meant that SRP did not provide Arizona “with
    control cost calculations at a level of detail that allowed for
    a comprehensive review.” Id. at 42,851. As a result, EPA
    explained, it “[did] not believe that [Arizona] was able to
    evaluate whether SRP’s control costs were reasonable.” Id.
    Arizona’s BART analysis was therefore inadequate because
    it “did not properly consider the costs of compliance for each
    control option.” Id.
    We conclude that EPA’s disapproval of the cost analysis
    underlying Arizona’s BART determination for Coronado on
    that basis was not “arbitrary, capricious, [or] an abuse of
    discretion.” 
    5 U.S.C. § 706
    (2)(A). Arizona simply relied on
    the cost data provided by SRP, despite the fact that the data
    failed to include sufficient detail for the State meaningfully
    to analyze the reasonableness of the costs of various control
    alternatives. States are required by statute to consider “costs
    of compliance” in making BART determinations. 
    42 U.S.C. § 7491
    (g)(2). When they are not presented with enough data
    to do so, EPA may reasonably conclude that their analysis is
    28            ARIZONA EX REL. DARWIN V. USEPA
    inadequate.14 EPA’s decision to do so was not arbitrary or
    capricious.
    (ii) The SIP’s Visibility Analysis
    As part of its BART analysis, a state must analyze “the
    degree of improvement in visibility which may reasonably be
    anticipated to result from the use” of alternative control
    technologies. 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A). EPA found no
    problems with the “technical adequacy of [Arizona’s
    visibility] modeling.” 77 Fed. Reg. at 72,519. Rather, EPA
    found Arizona’s interpretation of the visibility modeling for
    all three plants “problematic.” Id. The problems, EPA
    contends, resulted in Arizona understating the visibility
    benefits associated with installing SCR at Coronado. We
    conclude that EPA’s assessment of Arizona’s visibility
    analysis considered the appropriate factors rationally, and so
    defer to its conclusions. See Motor Vehicle Mfrs., 
    463 U.S. at 43
    .
    14
    EPA also disapproved the cost analysis for failing to use the
    “overnight method” required by the Cost Manual. The “overnight”
    method “treats the costs of a project as if the project were completed
    ‘overnight,’ with no construction period and no interest accrual.” 77 Fed.
    Reg. at 72,530. “Since assets under construction do not provide service
    to current customers,” utilities for ratemaking purposes use an alternative,
    “levelized” methodology, to “capitalize[] the interest and return on equity
    that would accrue over the construction period and adds them to the rate
    base when construction is completed and the assets are used.” Id.
    Because EPA had a sufficient alternative basis for disapproving the
    Coronado cost analysis, we do not here decide whether it could require
    Arizona to employ the overnight method. We discuss EPA’s use of the
    overnight method in its FIP infra, at 39–40.
    ARIZONA EX REL. DARWIN V. USEPA                  29
    For Coronado, Arizona used a “visibility index”
    averaging the visibility benefits at the closest nine Class I
    areas, but did not evaluate such benefits separately at the most
    impacted Class I area, the Gila Wilderness Area. 77 Fed.
    Reg. at 72,519; see also 77 Fed. Reg. at 42,850–51. EPA’s
    regulations “do not prescribe a particular approach to
    calculating or considering visibility benefits across multiple
    Class I areas,” 77 Fed. Reg. at 42,841; states have the
    “flexibility to assess visibility improvements due to BART
    controls by one or more methods,” Guidelines at 39,170. The
    indexing approach therefore “could be acceptable in itself as
    part of assessing multiple area impacts and improvements.”
    
    77 Fed. Reg. 72,519
    . But, EPA concluded, “without any
    consideration of particular area improvements, the averaging
    process causes especially large benefits at some individual
    areas to be diluted or lost, effectively discounting some of the
    more important effects of the controls.” 
    Id.
     (emphasis
    added).
    Moreover, regardless of the methodology used, EPA
    maintains, Arizona’s visibility analysis in its SIP was
    unreasonable because it used “two contrasting, yet
    equally incomplete, approaches to assessing visibility
    improvements.” Arizona used a visibility index average to
    analyze visibility benefits at Coronado, but its analyses for
    Apache and Cholla considered visibility improvements “only
    at the single Class I area with the greatest modeled impact
    from a facility,” rather than at all impacted Class I areas.
    77 Fed. Reg. at 72,519. That is, the cumulative averaging
    approach taken by Arizona in its analysis for Coronado “is
    counter to [Arizona’s] emphasis elsewhere in the SIP on the
    importance of considering the visibility improvement at the
    single area having the largest impact from a given facility.”
    Id. The upshot is the appearance that the State selectively
    30         ARIZONA EX REL. DARWIN V. USEPA
    chose for each plant a methodology that minimized the
    visibility improvement achieved by the more stringent
    emission controls at each location.
    Arizona made no attempt in its SIP, nor in its briefing in
    this appeal, to counter this appearance by explaining why it
    chose differing approaches to visibility analysis for different
    facilities. SRP may be correct that “[t]he Guidelines allow
    states to use either or both approaches.” But, as described
    above, a state must include in its SIP “an explanation of the
    CAA factors that led [the State] to choose that option over
    other control levels.” Guidelines at 39,170–71 (emphasis
    added). Adopting inconsistent — indeed, contradictory —
    approaches without providing any explanation for that
    decision frustrated EPA’s ability to “review the substantive
    content of the BART determination.” N. Dakota, 730 F.3d at
    761.
    Arizona also contends that the outcome of its BART
    determinations would not have changed even if it had adopted
    the approach to visibility analysis EPA prescribed. The
    visibility improvements resulting from installing SCR, the
    State maintains, would in any event be “imperceptible” to the
    human eye.
    EPA expressly, and reasonably, rejected this argument
    when it promulgated the Haze Regulations and Guidelines in
    2005:
    Even though the visibility improvement from
    an individual source may not be perceptible,
    it should still be considered in setting BART
    because the contribution to haze may be
    significant relative to other source
    ARIZONA EX REL. DARWIN V. USEPA               31
    contributions in the Class I area. Thus, we
    disagree that the degree of improvement
    should be contingent upon perceptibility.
    Failing to consider less-than-perceptible
    contributions to visibility impairment would
    ignore the CAA’s intent to have BART
    requirements apply to sources that contribute
    to, as well as cause, such impairment.
    70 Fed. Reg. at 39,129.
    In sum, EPA rationally determined that Arizona’s BART
    visibility analysis for Coronado was unsupported by
    explanation and inconsistent with the CAA and its
    regulations. We defer to its conclusions.
    (iii)      The SIP’s Choice of BART
    EPA’s Guidelines require states to support their BART
    determinations with “documentation for all required
    analyses,” including explanations of their BART five-factor
    analysis. 
    40 C.F.R. § 51.308
    (e)(1). Further, the Guidelines
    indicate that states “should provide a justification for
    adopting the technology . . . select[ed] as the ‘best’ level of
    control, including an explanation of the [Act’s] factors that
    led [the State] to choose that option over other control
    levels.” Guidelines at 39,170–71 (emphasis added). A state
    need not perform this analysis if a source already has, or has
    committed to installing, the most stringent controls available.
    
    Id. at 39,165
    . Otherwise, as EPA explained in proposing the
    Rule here at issue, “[s]tates are free to determine the weight
    and significance assigned to each factor, but must consider all
    five factors and provide a reasoned explanation for adopting
    [BART].” 77 Fed. Reg. at 42,838 (emphasis added).
    32          ARIZONA EX REL. DARWIN V. USEPA
    In the Final Rule, EPA concluded that, although Arizona
    “presented information relevant to each of the BART factors”
    and “expressly stated” that it had considered those factors, it
    did not “provide[] an explanation regarding how this
    information was used to develop its BART determinations.”
    77 Fed. Reg. at 72,517; see also id. at 72,566 (“[Arizona] has
    not demonstrated that it actually took into consideration the
    BART factors in making its determinations[.] . . . [I]t gave no
    explanation or rationale for how it reached a determination
    based on that information.”). More specifically, EPA found
    that Arizona did not discuss how the results of the visibility
    index were weighed against the other BART factors for
    Coronado. Id. at 72,518; 77 Fed. Reg. at 42,851. Further,
    EPA noted that while the SIP includes cost data, it “provides
    no explanation regarding how, or even if, th[e] cost
    information was used in arriving at its NOX BART
    determinations.” 77 Fed. Reg. at 72,517. Indeed, “[i]n the
    case of . . . Coronado, the . . . SIP does not analyze th[e] cost
    information in even a qualitative manner.” Id.
    A review of Arizona’s BART Technical Support
    Document supports EPA’s analyses with regard to Coronado.
    Arizona’s ultimate determination was that, “[a]fter reviewing
    the BART analysis provided by the company, and based upon
    the information above . . . BART control at [Coronado] for
    NOX is . . . Low NOX burners with OFA” with an emission
    rate of 0.32 lbs/mmBtu. Before announcing that decision,
    Arizona provided several charts of data concerning the
    various controls’ cost-effectiveness and visibility impacts.
    But, having done so, it provided no reasoning or rationale to
    justify its ultimate BART selection. There was simply
    no attempt made to explain why the State chose one
    control technology over another, or how it evaluated the
    various BART factors (i.e., cost-effectiveness, visibility
    ARIZONA EX REL. DARWIN V. USEPA                  33
    improvement, energy and non-air quality environmental
    impacts, existing pollution control technology in use, and the
    remaining useful life of the source), either individually or in
    combination.
    Indeed, Arizona does not meaningfully contest EPA’s
    adverse characterization of its BART analysis. Rather, it
    contends that “no great explanation is required to understand
    the State’s decision not to spend hundreds of millions of
    dollars of its citizens’ money for an imperceptible
    improvement in visibility.” Yet, under the Act and its
    implementing regulations, states are required in SIPs to
    explain the choice of BART, taking into account not only cost
    and visibility improvement, but also the three other BART
    factors. See 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A); Guidelines at
    39,170–71.
    We recently invalidated a FIP in part because EPA’s
    conclusory cost-benefit analysis “fail[ed] to reveal to a reader
    how EPA determined that the cost of controls were not
    justified.” NPCA, 788 F.3d at 1145. The same failure here,
    albeit by a state in its SIP, fares no better. Although the Act
    affords states significant discretion in determining the
    appropriate levels of BART controls, EPA must review
    whether a state’s determinations comply with the statute and
    its rules. See N. Dakota, 730 F.3d at 761; Oklahoma,
    723 F.3d at 1209. Just as we could not in NPCA review
    EPA’s cost/benefit analysis absent any coherent agency
    analysis, EPA reasonably determined that it could not
    meaningfully review Arizona’s parallel determination,
    because the State did not provide an adequate explanation of
    its underlying analysis, if any.               Cf. 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A); Guidelines at 39,170–71.
    34           ARIZONA EX REL. DARWIN V. USEPA
    In sum, EPA’s conclusion that Arizona did not adequately
    explain its NOX BART determinations provides reasonable
    support for its partial disapproval of Arizona’s SIP. We
    therefore defer to EPA’s determination.
    (iv)   Conclusion
    EPA reasonably concluded that Arizona’s cost and
    visibility impact analyses for Coronado suffered from
    significant analytical defects and that the SIP did not provide
    a reasoned explanation of the bases for the ultimate BART
    determination for Coronado. Although Section 169A affords
    the states substantial authority to determine BART controls,
    the combination of these defects provided EPA reasonable
    grounds upon which to disapprove the Arizona’s BART
    determinations as to NOX emissions limits at Coronado. Its
    partial disapproval of the SIP in this respect was not arbitrary
    or capricious.
    C. EPA’s Promulgation of the FIP
    To remedy the deficiencies it identified in its partial
    disapproval of Arizona’s SIP, EPA in the same Final Rule
    promulgated a FIP. As relevant here, EPA concluded that
    selective catalytic reduction with low-NOX burners and
    overfire air, “the most stringent available control option” for
    NOX emissions, was BART for Coronado. 77 Fed. Reg. at
    42,864. It thus proposed NOX emission limits of 0.05
    lb/mmBtu, based on a rolling 30-boiler-operating day
    average,15 for Coronado. Id. at 42,865. After receiving
    15
    “Boiler operating day means a 24–hour period between 12 midnight
    and the following midnight during which any fuel is combusted at any
    time in the steam-generating unit. It is not necessary for fuel to be
    ARIZONA EX REL. DARWIN V. USEPA                       35
    comments on its proposed rule, EPA’s Final Rule imposed a
    FIP containing revised NOX emission limits of 0.065
    lb/mmBtu, measured as an average of the two Coronado
    generating units. See 77 Fed. Reg. at 72,514–15. This final
    emission limit is, of course, very significantly more stringent
    than the 0.32 lb/mmBtu NOX limit proposed by Arizona in its
    SIP. As required by the Guidelines, EPA explained its
    general analytical approach and BART determinations at
    substantial length in the Final Rule. See id. at 72,526–35.
    SRP presses a number of substantive challenges to the
    FIP’s emission limit, as well as to EPA’s analysis underlying
    that determination. Arizona, on the other hand, challenges
    EPA’s decision to promulgate a FIP in the same rule in which
    it disapproved in part Arizona’s SIP. We address these
    challenges in turn.
    1. The FIP’s BART Determinations
    Under Section 169A and the Haze Regulations, EPA must
    perform the same BART analysis when promulgating a
    regional haze FIP as that performed by states in developing
    SIPs. See 
    42 U.S.C. § 7491
    (b)(2)(A), (g)(2); see also 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A)–(B). Challenges to the FIP are
    reviewed “under the same arbitrary and capricious standard
    . . . used to evaluate the EPA’s rejection of the SIP.”
    Oklahoma, 723 F.3d at 1215. But this review requires a
    “slightly different perspective,” as we “evaluat[e] the EPA’s
    own choices under the guidelines, as opposed to evaluating its
    combusted the entire 24–hour period.” 
    40 C.F.R. § 60.41
    . At the end of
    each boiler operating day, emissions are measured and a new 30-day
    rolling average is calculated. See 
    40 C.F.R. § 60
    .48Da(b).
    36          ARIZONA EX REL. DARWIN V. USEPA
    choice to reject [Arizona’s] SIP under the guidelines.” 
    Id.
    (emphasis added).
    SRP contends that EPA’s cost and visibility analyses
    contained in its FIP were arbitrary and capricious. It also
    maintains that, for a number of reasons, the FIP’s NOX
    emission limits are neither achievable nor reasonable.
    Consequently, it argues, the FIP’s BART determinations for
    Coronado were, on the whole, arbitrary and capricious. For
    the reasons set forth below, we in the main do not agree, but
    we leave one issue open because EPA is reconsidering it.
    a. EPA’s Visibility Analysis
    SRP first disputes EPA’s “cumulative” approach. EPA
    estimated the visibility improvements that would occur at
    each of the Class I areas potentially impacted by Coronado’s
    emissions and then aggregated those improvements. SRP
    contends this analysis resulted in “a large deciview number”
    that does not represent the actual perception of visibility
    conditions at any particular Class I area. SRP’s challenge to
    EPA’s visibility improvement analysis suffers from two
    substantial defects.
    First, EPA considered the “cumulative visibility
    improvement” resulting from various control technologies
    “[a]s a supplement” to considering deciview improvements
    at individual Class I areas. For Coronado, specifically, EPA
    explained that modeling showed that SCR control technology
    would result in visibility benefits at each of eleven Class I
    areas—including the Gila Wilderness Area, which EPA
    faulted Arizona for failing to consider—as well as on a
    cumulative basis. See 77 Fed. Reg. at 42,863 tbl.23. In
    response to Petitioners’ comments critiquing EPA’s
    ARIZONA EX REL. DARWIN V. USEPA                  37
    cumulative approach, EPA explained in the Final Rule that
    “[t]he approach is simply one way of assessing improvements
    at multiple areas, for consideration along with other visibility
    metrics.” 77 Fed. Reg. at 72,532. SRP’s claim that EPA
    “focused on this [cumulative] methodology almost
    exclusively” is simply not supported by the record.
    Second, SRP’s insistence on “human perception” as the
    determinative “cornerstone” for the BART determinations for
    each individual source is overstated. As discussed above,
    when promulgating the BART Guidelines, EPA explicitly
    disagreed “that the degree of improvement should be
    contingent upon perceptibility” when determining BART for
    an individual source. 70 Fed. Reg. at 39,129.
    EPA’s Final Rule provided a fully adequate explanation
    of its application of the deciview concept in the FIP. Again,
    one deciview is the minimum visibility difference people can
    perceive. See Guidelines at 39,120 n.32. The Guidelines
    suggest that states use a minimum threshold of 0.5 deciviews
    to determine whether a source is subject to BART controls.
    EPA explained in its Final Rule, however, that “[s]maller
    improvements from controls should be considered in BART
    determinations, since they can be beneficial in considering
    effects from controls on multiple sources.” 77 Fed. Reg. at
    72,533 (emphasis added).
    In conclusion, EPA’s visibility improvement assessment
    was consistent with the statute and regulatory requirements,
    and supported by the record.
    38         ARIZONA EX REL. DARWIN V. USEPA
    b. EPA’s Cost Analysis
    SRP also challenges EPA’s cost analysis, arguing that it
    “diverged” from the Guidelines and was “inadequate” to
    support its BART determinations for NOX emissions.
    Additionally, SRP argues that EPA’s cost assessment was
    flawed “because [EPA] insisted on rigid adherence to the
    [Cost Manual] irrespective of site-specific costs.”
    EPA explains that it used the “air pollution control cost
    development” component of the Integrated Planning Model
    (“IPM”) to develop its cost estimates. See 77 Fed. Reg. at
    72,530. IPM, a model of the United States electric power
    sector, “relies upon a very large number of data inputs and
    provides forecasts” of costs and other variables relevant to
    decisionmaking in that sector. Id. SRP maintains that by
    using IPM cost estimates, EPA ignored the Coronado
    facility’s “site-specific characteristics,” and so understated
    the actual costs of compliance for installing controls at
    Coronado.
    In the Final Rule, however, EPA explained that it did not
    rely on IPM as a whole, but rather on “one component of
    IPM, specifically, the component that develops the costs of
    air pollution control technologies.” Id. As EPA explained,
    that cost development methodology was not “generic” or
    “generalized.” Id. Rather, it was grounded in databases of
    actual SCR projects from 2004, 2006, and 2009. Id. At the
    same time, EPA recognized that “a costly engineering
    evaluation that included site visits would potentially produce
    a more refined cost estimate that could be considered more
    site-specific than our own.” Id.
    ARIZONA EX REL. DARWIN V. USEPA                          39
    In addition, in response to Petitioners’ public comments
    contending that EPA failed to consider site-specific
    information, EPA conducted supplemental cost analyses that
    relied upon “cost estimates provided by SRP.” See id. at
    72,558–60. Based on this supplemental cost analysis, EPA
    concluded that “the cost-effectiveness values of SCR . . . [are]
    not . . . cost-prohibitive” for Coronado. Id. at 72,560.
    Not satisfied, SRP contends that in its supplemental
    analysis, “EPA excluded costs it deemed inconsistent with the
    [Cost Manual]” such as Allowance for Funds Utilized During
    Construction (“AFUDC”).16           This argument restates
    Petitioners’ objections to EPA’s reliance on the overnight
    costing methodology when it partially disapproved Arizona’s
    SIP. See supra note 14. EPA’s use of such a methodology in
    its own FIP’s cost analysis is, without doubt, reasonable. See
    77 Fed. Reg. at 72,518.
    In rejecting Arizona’s SIP, EPA explained that the use of
    the overnight method was “crucial to [its] ability to assess the
    reasonableness of the costs of compliance.” Id. The agency
    went on:
    A proper evaluation of cost-effectiveness
    allows for a reasoned comparison not only of
    different control options for a given facility,
    but also of the relative costs of controls for
    similar facilities. If the cost-effectiveness of
    a control technology for a particular facility is
    outside the range for other similar facilities,
    16
    “AFUDC primarily represents a tool for utilities to capture their cost
    of borrowing and return on equity during construction periods.” 77 Fed.
    Reg. at 72,531.
    40         ARIZONA EX REL. DARWIN V. USEPA
    the control technology may be rejected as
    not cost-effective. . . . Without an
    ‘apples-to-apples’ comparison of costs, it is
    impossible to draw rational conclusions about
    the reasonableness of the costs of compliance
    for particular control options. Use of the
    [Cost Manual] methodology is intended to
    allow a fair comparison of pollution control
    costs between similar applications for
    regulatory purposes.
    Id. EPA concluded that “it is reasonable for us to insist that
    the [Cost Manual] methodology be observed in the cost
    estimate process.” Id. Accordingly, it rejected comments
    that items like AFUDC should have been incorporated into its
    cost analysis, as they were “inconsistent with [the Cost
    Manual] methodology.” Id. at 72,531.
    EPA’s analysis is reasonable. The purpose of the cost
    analysis required as part of a BART determination is to foster
    comparison of the cost of the visibility improvements enabled
    by various control technologies. As EPA’s comments
    indicate, cross-facility comparisons of similar sources with
    regard to the cost-effectiveness of a given control option aid
    in determining cost-effectiveness at a specific source.
    Control options are likely to impact similar sources similarly;
    comparisons assure that the cost and benefit figures used for
    a particular site are realistic, rather than inflated in one
    direction or another. Consideration of AFUDC would not
    further this inquiry, as AFUDC is ultimately reflective of the
    implementing entity’s financial and logistical situations,
    grounded in past decisions and in the company’s financial
    policies and attitudes, not of the hard costs of the equipment
    and construction, which should be consistent across sites.
    ARIZONA EX REL. DARWIN V. USEPA                 41
    While AFUDC and similar concepts are relevant for sales and
    ratemaking, including them would undermine the sort of
    “apples-to-apples” comparison that EPA asserts is necessary
    as part—but only part—of assessing the control options.
    This approach is consonant with the Guidelines, which
    specifically advise that “reasonable range[s]” for cost
    effectiveness are those that are “consistent with the range of
    cost effectiveness values used in other similar permit
    decisions over a period of time.” Guidelines at 39,168; see
    also Oklahoma, 723 F.3d at 1213 (“The guidelines say that
    states should follow the manual’s methodology so that
    projects can be more easily compared.”). Moreover, adopting
    a costing methodology which focuses on achieving
    consistency and facilitating comparisons aligns with the CAA
    itself, which empowers EPA to promulgate national
    regulations concerning BART determinations. See 
    42 U.S.C. § 7491
    (a)(4), (b)(1).
    Accordingly, we reject SRP’s argument that the FIP’s
    underlying cost analysis was arbitrary and capricious.
    c. Achievability of the FIP’s NOX emission limits for
    Coronado
    The Haze Regulations provide that the BART
    determination “must be based on an analysis of the best
    system of continuous emission control technology available
    and associated emission reductions achievable for each
    BART-eligible source that is subject to BART.” 
    40 C.F.R. § 51.308
    (e)(1)(ii)(A) (emphasis added). The reviewing
    authority should “take into account the most stringent
    emission control level that the technology is capable of
    achieving,” by considering “recent regulatory decisions and
    42            ARIZONA EX REL. DARWIN V. USEPA
    performance data (e.g., manufacturer’s data, engineering
    estimates and the experience of other sources).” Guidelines
    at 39,166.
    SRP argues that the FIP’s NOX emission limit for
    Coronado — 0.065 lb/mmBtu averaged across the facility —
    is not achievable. More specifically, it argues that (1) the
    emission limits are technically infeasible; and (2) EPA did
    not take into account the Consent Decree binding Coronado
    Unit 2 when formulating the emission limits.
    Both of these arguments will be rendered moot if EPA’s
    recent action proposing to revise the FIP’s NOX emission
    limit for Coronado results in a final revised FIP consistent
    with the proposal. See 
    80 Fed. Reg. 17,010
     (March 31,
    2015).17 The proposed revision would replace the facility-
    wide compliance method with “a unit-specific compliance
    method for determining compliance with . . . BART []
    emission limits for nitrogen oxides,” and would establish
    “unit-specific limit[s]” of 0.065 lb/mmBtu for Coronado Unit
    1 and 0.080 lb/mmBtu for Coronado Unit 2. 
    Id.
    SRP’s technical feasibility argument was largely based on
    the assertion that a 0.050 lb/mmBtu emissions limit — which
    SRP contended Coronado Unit 1 would have to satisfy —
    was “infeasible” for SCR retrofits to coal-fired electric
    generating units. Even though EPA based its BART
    determinations for Coronado on modeling showing that SCR
    controls could achieve a 0.050 lb/mmBtu NOX emission rate
    with an 80%–90% control efficiency, see 77 Fed. Reg. at
    42,853, and has imposed a NOX emission limit in the 0.050
    17
    EPA has recently informed us that it expects to issue the final revised
    FIP by March 2016.
    ARIZONA EX REL. DARWIN V. USEPA                          43
    lb/mmBtu range in other, similar rulemakings, see 77 Fed.
    Reg. at 72,544 tbl.7, the proposed revised FIP’s limits for
    Coronado Unit 1 are now 0.065 lb/mmBtu.18 Likewise,
    although SRP initially argued that the FIP’s emission limits
    were inconsistent with the limits prescribed by a pre-existing
    Consent Decree as to Coronado Unit 2, EPA’s proposed FIP
    revision establishes the same emissions limit as that
    prescribed by the Consent Decree: 0.080 lb/mmBtu. See
    80 Fed. Reg. at 17,016–18. Consequently, these arguments,
    whatever merit they may have had as to the original FIP, will
    not carry force if the proposed revised FIP is adopted.
    Additionally, SRP argues that the FIP’s emissions limits
    are in conflict with EPA’s own “presumptive” limits. The
    BART Guidelines provide a list of “presumptive NOX limits,”
    based on boiler and coal type, for certain coal-fired
    generating units operating without post-combustion controls.
    Guidelines at 39,171. Under the Guidelines, the reviewing
    authority “should require such [facilities] to meet the
    [presumptive] NOX emission limits, unless [it] determine[s]
    that an alternative control level is justified based on
    consideration of the statutory factors.” Id. The presumptive
    NOX limits for Coronado are 0.32 lb/mmBtu for bituminous
    coal and 0.23 lb/mmBtu for sub-bituminous coal. Id. tbl.1.
    Arizona’s SIP proposed a NOX emission limit for Coronado
    within the presumptive limit range, while the FIP imposes a
    far lower facility-wide limit. SRP argues that EPA, unlike
    Arizona, did not consider the presumptive limits, and
    therefore violated the Guidelines.
    18
    A 0.065 lb/mmBtu emissions limit may also be, in SRP’s view,
    technically infeasible, and SRP is entitled to petition for review of EPA’s
    action finalizing the FIP revision when it is issued. See 
    42 U.S.C. § 7607
    (b).
    44         ARIZONA EX REL. DARWIN V. USEPA
    As the Final Rule explains, EPA did consider the
    presumptive limits but found there is “no single presumptive
    NOX limit that applies to any of these units,” as each of the
    facilities “historically burned both bituminous and sub-
    bituminous coal.” 77 Fed. Reg. at 72,529. Accordingly, EPA
    instead “considered the technological basis for presumptive
    NOX BART limits . . . as part of the five-factor analysis [it]
    performed for each facility.” Id.
    In any event, SRP’s argument that the “law requires [the
    presumptive] limits to be taken into account in any BART
    determination” is belied by the Guidelines. The presumptive
    emission limits are “rebuttable” and “do[] not preclude states
    or EPA from setting limits that differ from those
    presumptions.” 77 Fed. Reg. at 72,529. Instead, the
    Guidelines expressly allow for an alternative control level to
    be formulated based on the statutory factors, provided that the
    alternative limits are based on a reasoned BART analysis.
    70 Fed. Reg. at 39,171. Moreover, the presumptive emission
    limits are presumed to be cost-effective, not presumed to be
    BART in every case. See 77 Fed. Reg. at 51,620, 51,633
    (Aug. 24, 2012); 
    77 Fed. Reg. 14,604
    , 14,665 (Mar. 12,
    2012).
    In sum, EPA acted reasonably in departing from
    Guidelines’ rebuttable presumptive limits. But, because EPA
    has not yet completed its proposed revised FIP, we decline to
    rule on the reasonableness of its emissions limits, as they are
    likely to be altered. This aspect of these proceedings is
    therefore stayed until EPA concludes the administrative
    process and issues its final revised FIP.
    ARIZONA EX REL. DARWIN V. USEPA                  45
    2. Simultaneous Disapproval            of   a   SIP    and
    Promulgation of a FIP
    Apart from its substantive challenges to the FIP, Arizona
    contends that EPA procedurally erred in promulgating the FIP
    in the same rule as its partial disapproval of the SIP. That is
    not so.
    Under the Act, EPA shall promulgate a FIP “at any time
    within 2 years” after EPA disapproves a SIP in whole or in
    part or finds that a state has not made a required submission.
    
    42 U.S.C. § 7410
    (c) (emphasis added). A state may forestall
    the promulgation of a FIP if it “corrects the deficiency, and
    [EPA] approves the plan or plan revision, before [EPA]
    promulgates such [FIP].” 
    Id.
     Furthermore, a state may
    submit a SIP revision to EPA at any time, and EPA must act
    on it within twelve months of submission. 
    Id.
     § 7410(k).
    The Final Rule’s partial disapproval of Arizona’s BART
    determinations constituted a trigger under the Act for
    promulgating a FIP replacing those elements. The Act
    expressly authorizes EPA to promulgate a FIP “at any time”
    within two years of disapproving a SIP. “At any time,” of
    course, includes simultaneously with the SIP’s disapproval.
    See Oklahoma, 723 F.3d at 1223.
    Arizona ultimately recognizes that EPA had the authority
    to promulgate the FIP simultaneously with its partial
    disapproval, but maintains that EPA did not realize that it had
    discretion to provide Arizona up to two years to correct any
    deficiencies. EPA, Arizona posits, harbored the erroneous
    belief that its obligations under the Consent Decree required
    it to act when it did.
    46          ARIZONA EX REL. DARWIN V. USEPA
    Some procedural background is required to understand
    the thrust of Arizona’s argument. After EPA did not
    promulgate FIPs within two years of its January 2009 finding
    that many states, including Arizona, had not submitted
    required SIPs, it entered into a Consent Decree requiring the
    federal agency to approve a SIP or promulgate a FIP by
    November 15, 2012. See supra, p. 13–14. In the Final Rule,
    EPA stated that the Consent Decree “required [it] to issue a
    FIP for any portion of the Arizona SIP that we cannot
    approve.” 77 Fed. Reg. at 72,569. EPA further explained
    that “while . . . in the absence of an expired statutory duty and
    a court-ordered deadline to issue a FIP, it would be preferable
    for us to give Arizona additional time to revise its Regional
    Haze SIP prior to promulgation of a FIP, we simply do not
    have this option under these circumstances.” Id. at 72,571.
    Arizona contends that the January 2009 finding
    constituted only a determination that Arizona failed to submit
    a Section 309 SIP, and that the correct remedy for Arizona’s
    asserted deficiency “was to impose a FIP supplying the
    missing Section 309 elements, not to impose a FIP under
    Section 308, as it did here.” But, as we explained earlier, see
    supra, p. 11–12, Section 309 provides an alternative
    mechanism for western states to comply with the CAA’s
    visibility requirements for certain Class I areas. Such states
    must include Section 308 components for other Class I areas,
    and they remain subject to Section 308’s requirements if they
    do not submit a Section 309 SIP. See 
    40 C.F.R. § 51.309
    (a),
    (e), (g)(2). Arizona expressly acknowledged that its Section
    309 SIP submission lacked certain requirements under
    sections 51.309(d)(4)(viii) and (g). Because the State did not
    submit an adequate Section 309 SIP, it did not submit an
    adequate regional haze SIP. EPA was required to promulgate
    ARIZONA EX REL. DARWIN V. USEPA                   47
    a FIP to fill in the gap. See 
    42 U.S.C. §§ 7410
    (c)(1),
    7491(b)(2)(A).
    More practically, it is unlikely that a different outcome
    would have resulted if EPA had provided Arizona with
    additional time to correct its Section 308 SIP. EPA had
    expressed a number of its concerns to Arizona after reviewing
    its proposed SIP in late 2010. EPA also identified the basis
    for its proposed partial disapproval in its July 2012 proposed
    rule. Arizona made no effort to correct its SIP in light of
    these comments. There is no reason to think it would have
    done so after the Final Rule disapproving the SIP issued
    either.
    In sum, EPA properly promulgated its FIP in the same
    rule as its partial disapproval of the SIP. Further, as EPA
    stated in the Final Rule, the State remains free to, at any time,
    “submit a revised SIP to replace the FIP.” 77 Fed. Reg. at
    72,571.
    IV. CONCLUSION
    For the reasons set forth above, we deny Arizona’s and
    SRP’s petitions for review of EPA’s Final Rule as to EPA’s
    disapproval of Arizona’s SIP. Our ultimate review of EPA’s
    FIP, however, must await EPA’s final action on its proposal
    to revise the FIP in specific respects. As noted, EPA has
    stated that it expects to finalize the revised FIP by March
    2016. Accordingly we stay these proceedings as to
    evaluation of the FIP’s technical feasibility until the
    administrative process is complete.
    PETITIONS DENIED.
    48        ARIZONA EX REL. DARWIN V. USEPA
    GLOSSARY OF ACRONYMS
    AFUDC – Allowance for Funds Utilized During Construction
    APA – Administrative Procedure Act
    CAA – Clean Air Act
    BACT – Best Available Control Technology
    BART – Best Available Retrofit Technology
    EPA – Environmental Protection Agency
    FIP – Federal Implementation Plan
    IPM – Integrated Planning Model
    LNB – Low NOX Burner
    NOX – Nitrogen Oxides
    OAQPS – Office of Air Quality Planning and Standards
    OFA – Overfire Air
    PSD – Prevention of Significant Deterioration
    SCR – Selective Catalytic Reduction
    SIP – State Implementation Plan
    SO2 – Sulfur Dioxide
    ARIZONA EX REL. DARWIN V. USEPA          49
    SRP – Salt River Project Agricultural Improvement and
    Power District