                 FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


SIERRA CLUB; CENTER FOR                 No. 11-73342
BIOLOGICAL DIVERSITY;
GREENACTION FOR HEALTH AND
ENVIRONMENTAL JUSTICE,
                      Petitioners,

                 v.

U.S. ENVIRONMENTAL PROTECTION
AGENCY; LISA P. JACKSON, in her
official capacity as Administrator,
U.S. Environmental Protection
Agency; GINA MCCARTHY, in her
official capacity as Assistant
Administrator, Office of Air and
Radiation, U.S. Environmental
Protection Agency,
                         Respondents,

AVENAL POWER CENTER,
          Respondent-Intervenor.
2                    SIERRA CLUB V. U.S. EPA

 EL PUEBLO PARA EL AIRE Y AGUA                         No. 11-73356
 LIMPIO,
                         Petitioner,

                       v.                                OPINION

 U.S. ENVIRONMENTAL PROTECTION
 AGENCY; LISA P. JACKSON, in her
 official capacity as Administrator of
 the USEPA; JARED BLUMENFELD, in
 his official capacity as Regional
 Administrator for Region IX of the
 USEPS,
                           Respondents,

 AVENAL POWER CENTER,
           Respondent-Intervenor.

         On Petition for Review of an Order of the
       United States Environmental Protection Agency

                    Argued and Submitted
          October 8, 2013—San Francisco, California

                       Filed August 12, 2014

Before: N. Randy Smith and Jacqueline H. Nguyen, Circuit
   Judges, and Gordon J. Quist, Senior District Judge.*

                     Opinion by Judge Nguyen


  *
    The Honorable Gordon J. Quist, Senior District Judge for the U.S.
District Court for the Western District of Michigan, sitting by designation.
                    SIERRA CLUB V. U.S. EPA                            3

                           SUMMARY**


                       Environmental Law

    The panel granted a petition for review brought by
environmental groups, and vacated the Environmental
Protection Agency’s decision to issue a Prevention of
Significant Deterioration Permit, allowing Avenal Power
Center LLC to build and operate the Avenal Energy Project,
a 600 megawatt natural gas-fired power plant, under the old
air quality standards.

    The panel held that petitioners had standing because a
number of the petitioners had associational standing to
challenge EPA’s action. Turning to the merits, the panel held
that the EPA exceeded its authority under the Clean Air Act.
The panel applied Chevron, U.S.A., Inc. v. Natural Resources
Defense Council, Inc., 467 U.S. 837, 842 (1984), analysis,
and held that the Clean Air Act unambiguously required
Avenal Power to demonstrate that the Avenal Energy Project
complied with the regulations in effect at the time the Permit
was issued. The panel further held that because Congress had
directly spoken on the issue, the EPA could not waive this
requirement. The panel remanded for further proceedings.




  **
     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               SIERRA CLUB V. U.S. EPA

                       COUNSEL

Paul R. Cort (argued) and George Torgun, Earthjustice,
Oakland, California, for Petitioners Sierra Club, Center for
Biological Diversity, and Greenaction for Health and
Environmental Justice.

Ingrid Brostrom and Brent Newell, Center on Race, Poverty
& the Environment, San Francisco, California, for Petitioner
El Pueblo Para El Aire y Agua Limpio.

Ignacia S. Moreno, Assistant Attorney General, and
Stephanie J. Talbert (argued), United States Department of
Justice, Environment & Natural Resources Division,
Washington, D.C.; Brian Doster, David Coursen, Melina
Williams, and Julia Walters, United States Environmental
Protection Agency, for Respondents.

William R. Warne (argued), Jane E. Luckhardt, Elizabeth B.
Stallard, Gregory T. Broderick, and Nicholas Rabinowitch,
Downey Brand LLP, Sacramento, California, for Respondent-
Intervenor.

John J. Davis, Jr. and Andrew J. Kahn, Davis, Cowell &
Bowe, LLP, San Francisco, California, for Amici Curiae
Avenal-Area Unions.
                 SIERRA CLUB V. U.S. EPA                    5

                         OPINION

NGUYEN, Circuit Judge:

    Avenal Power Center LLC (“Avenal Power”) applied to
the United States Environmental Protection Agency (“EPA”)
for a Prevention of Significant Deterioration Permit
(“Permit”), to build and operate the Avenal Energy Project,
a 600 megawatt natural gas-fired power plant in the city of
Avenal, California. Although EPA had a statutory duty under
the Clean Air Act to either grant or deny the Permit
application within one year, 42 U.S.C. § 7475(c), it failed to
do so. After the deadline passed but before taking any final
action, EPA tightened the applicable air quality standards.
Avenal Power filed suit and sought to compel EPA to issue
the Permit under the old standards that would have applied
had EPA acted within the statutory deadline. Initially, EPA
responded that it could not legally do so, because the Clean
Air Act explicitly requires any newly constructed facility to
employ the best available control technology (“BACT”) for
regulated pollutants and meet air quality standards in effect
at the time a permit is issued.             See 42 U.S.C.
§ 7475(a)(3)–(4). Months later, however, EPA reversed
course and granted Avenal Power the Permit without regard
to the new regulations, which by then had gone into effect.
EPA contends that, under narrow circumstances, it has the
authority to grandfather certain permit applications like
Avenal Power’s, and that its decision is entitled to deference
under Chevron, U.S.A., Inc. v. Natural Resources Defense
Council, Inc., 467 U.S. 837, 842 (1984). The Sierra Club,
Greenaction for Health and Environmental Justice, Center for
Biological Diversity, and El Pueblo para el Aire y Agua
Limpio (collectively “Petitioners”), challenge EPA’s action.
6                SIERRA CLUB V. U.S. EPA

    Applying Chevron, we hold that the Clean Air Act
unambiguously requires Avenal Power to demonstrate that
the Avenal Energy Project complies with the regulations in
effect at the time the Permit is issued. Because “Congress has
directly spoken to the precise question at issue,” Chevron,
467 U.S. at 842, EPA cannot waive this requirement. We
therefore GRANT the Petition for review, VACATE the
decision to issue the Permit, and REMAND for proceedings
consistent with this opinion.

                     BACKGROUND

    Avenal Power proposes to build and operate a power
plant, the Avenal Energy Project, near the agricultural
communities of Avenal, Huron, and Kettleman City, within
California’s San Joaquin Valley Pollution Control District.
The facility would generate electricity from two 180-
megawatt natural gas combustion turbine generators, and a
300-megawatt steam turbine generator that utilizes heat from
the combustion turbines. According to EPA, the facility “will
be equipped with state-of-the-art control technology and will
be one of the lowest emitting power plants of its kind.” It is
undisputed, however, that its expected emissions of several
pollutants, including nitrogen dioxide (“NO2”), carbon
dioxide (“CO2”), and sulfur dioxide (“SO2”), are sufficient to
subject it to regulation under the Clean Air Act.

    On February 15, 2008, Avenal Power submitted an
application to EPA for a Permit. The Regional Administrator
determined the application to be administratively complete on
March 19, 2008. As of that date, EPA had not yet
promulgated national ambient air quality standards
(“NAAQS”) for NO2 or SO2 emissions, or BACT
requirements for greenhouse gases, including CO2. NAAQS,
                 SIERRA CLUB V. U.S. EPA                     7

which are regularly reviewed and revised by the EPA
Administrator, set hourly limits on the emission of designated
pollutants. See 42 U.S.C. §§ 7409, 7409(d)(1); 40 C.F.R.
§ 52.21(b)(50). The BACT requirement consists of “an
emission limitation based on the maximum degree of
reduction of each [regulated] pollutant” that EPA determines
is achievable “through application of production processes
and available methods, systems, and techniques” in view of
“energy, environmental, and economic impacts and other
costs.” 42 U.S.C. § 7479(3).

    On June 16, 2009, after the one-year decision making
period had elapsed, see 42 U.S.C. § 7475(c), the Regional
Administrator finally issued a Statement of Basis describing
the reasons for the proposed approval of the Permit. The
Statement of Basis is subject to notice and comment
procedures that afford the public an opportunity to participate
in the review process by submitting written comments and
appearing at a hearing to voice support or concern. See
42 U.S.C. § 7475(a)(2); 40 C.F.R. §§ 124.10–12. During the
comment period in this case, EPA held an informational
meeting and two hearings. Concerned that the Avenal Energy
Project would adversely impact the environment and health
and quality of life of local residents, Petitioners filed
comments opposing issuance of the Permit.

     While Avenal Power’s Permit application was still under
consideration, EPA adopted more stringent NAAQS and
revised the BACT requirement. Specifically, EPA tightened
NAAQS for NO2, capping hourly emissions at 100 parts per
billion (“ppb”), with the new regulations to take effect on
April 12, 2010. See Primary National Ambient Air Quality
Standards for Nitrogen Dioxide, 75 Fed. Reg. 6,474, 6,475
(Feb. 9, 2010). EPA further subjected greenhouse gases such
8                   SIERRA CLUB V. U.S. EPA

as CO2 to BACT requirements, effective January 2, 2011.
See Reconsideration of Interpretation of Regulations That
Determine Pollutants Covered by Clean Air Act Permitting
Programs, 75 Fed. Reg. 17,004 (Apr. 2, 2010). Finally, EPA
published a final rule establishing a new hourly SO2 NAAQS
of 75 ppb, to become effective August 23, 2010. See Primary
National Ambient Air Quality Standards for Sulfur Dixoide,
75 Fed. Reg. 35,520 (June 22, 2010).

    Facing a slew of new regulations, and frustrated by the
delay, Avenal Power filed suit on March 9, 2010, in the
United States District Court for the District of Columbia, to
compel EPA to issue the Permit. Two months later, EPA
requested that Avenal Power complete a cumulative air
impact assessment of the Avenal Energy Project’s hourly
NO2 emissions to address its compliance with the revised
NAAQS. Although Avenal Power cooperated and submitted
additional documentation, the process took months.

    In late August 2010, after the new NO2 and SO2 NAAQS
had gone into effect, Avenal Power requested an expedited
judgment on the pleadings from the D.C. district court in an
effort to compel EPA to issue the Permit without
consideration of the newly effective regulations. EPA
opposed the motion, arguing that even though it missed the
one-year statutory deadline to act on Avenal Power’s
application, the Clean Air Act prohibits the agency from
granting the Permit unless Avenal Power complies with the
superseding standards. In support of its position, EPA cited
public guidance issued by the Director of its Office of Air
Quality Planning and Standards.1 See Memorandum from

 1
   We take judicial notice of this document as a public record. Fed. R.
Evid. 201; Lee v. City of Los Angeles, 250 F.3d 668, 690 (9th Cir. 2001).
                    SIERRA CLUB V. U.S. EPA                           9

Stephen D. Page, EPA Office of Air Quality Planning and
Standards, Applicability of the Federal Prevention of
Significant Deterioration Permit Requirements to New and
Revised National Ambient Air Quality Standards (Apr. 1,
2010) (hereinafter “Page Memo”), available at
http://www.epa.gov/region7/air/nsr/nsrmemos/psdnaaqs.pdf.
EPA also promised the district court it would issue a final
decision by December 31, 2010—that is, before the revised
regulations on greenhouse gases went into effect on January
2, 2011. It eventually became clear, however, that a final
decision would not be forthcoming by that date, further
forestalling administrative proceedings.2 And sure enough,
the deadline passed without a final decision.

    At this point, after conducting what it described as a
“policy review,” EPA reversed course. In a declaration
submitted to the D.C. district court, EPA contended that
“EPA believes it is appropriate to grandfather,” i.e., exempt,
Avenal Power’s application from the NO2 and SO2 hourly
NAAQS, and the BACT requirement for greenhouse gases.
EPA concluded that it possessed inherent grandfathering
authority even absent express authorization under the Clean
Air Act or related regulations. The EPA Administrator then
transferred authority to issue a final decision on Avenal
Power’s application from the Regional Administrator for
Region 9 to the Assistant Administrator for the Office of Air
and Radiation. Consistent with its representation to the
district court, EPA issued a Supplemental Statement of Basis


 2
   EPA apparently took the position that the Avenal Energy Project would
not run afoul of the new SO2 hourly NAAQS. Nonetheless, EPA
determined that compliance with the revised SO2 and greenhouse gases
regulations would require further public notice and comment proceedings,
as well as hearings.
10                   SIERRA CLUB V. U.S. EPA

proposing to grandfather the application under the old air
quality standards in effect at the time the application was
submitted.

    Petitioners submitted comments to EPA objecting to
issuance of the Permit, and EPA’s assertion of grandfathering
authority. On May 26, 2011, as the administrative process
continued to drag on, the district court granted in part Avenal
Power’s motion for judgment on the pleadings and ordered
the EPA Administrator to render a decision by May 27, 2011,
and a final, non-appealable, agency action ripe for judicial
review by August 27, 2011. The next day, the Assistant
Administrator for the Office and Air and Radiation published
EPA’s responses to the public comments, and issued the
Permit.

    Petitioners appealed to the Environmental Appeals Board,
which declined to exercise jurisdiction to review EPA’s
asserted grandfathering authority, given the time constraint
imposed by the D.C. district court for a final administrative
action, but otherwise upheld issuance of the Permit.3
Petitioners timely filed two separate petitions for judicial
review, chiefly challenging EPA’s interpretation of its
statutory authority under the Clean Air Act.

   We have jurisdiction pursuant to 42 U.S.C. § 7607(b)(1),
and consolidated the two petitions for review. Avenal Power


     3
      The Environmental Appeals Board also held that the Assistant
Administrator (rather than the Regional Administrator) was authorized to
issue the Permit, and that EPA’s environmental justice analysis comported
with Executive Order 12898. Because we hold that EPA exceeded its
statutory authority, we need not address the latter issue, which Petitioners
also raise for review.
                    SIERRA CLUB V. U.S. EPA                          11

successfully moved to intervene in these proceedings, and the
United Association of Plumbers and Pipefitters Local 246,
International Brotherhood of Electric Workers Local 100, and
Insulators Local 16 successfully moved to file a brief as amici
curiae.

                            ANALYSIS

                                   I

    As an initial matter, Avenal Power, though not EPA,
suggests that Petitioners lack standing. It falls to Petitioners,
as the parties invoking federal jurisdiction, to demonstrate
standing.4 Lujan v. Defenders of Wildlife, 504 U.S. 555, 561
(1992). However, only one Petitioner must establish standing
to enable review. Massachusetts v. EPA, 549 U.S. 497, 518
(2007).

    “An association has standing to bring suit on behalf of its
members when its members would otherwise have standing
to sue in their own right, the interests at stake are germane to
the organization’s purpose, and neither the claim asserted nor
the relief requested requires the participation of individual
members in the lawsuit.” Wilderness Soc’y, Inc. v. Rey,
622 F.3d 1251, 1256 (9th Cir. 2010) (quoting Friends of the
Earth, Inc. v. Laidlaw Envt’l Servs. (TOC), Inc., 528 U.S.
167, 181 (2000)). The record reflects, and Avenal Power

  4
    Petitioners were not required to establish standing before EPA, and
they now seek leave to submit declarations to establish standing for
purposes of this appeal. Avenal Power does not oppose the request, and
we grant it. See Nw. Envt’l Def. Ctr. v. Bonneville Power Admin.,
117 F.3d 1520, 1528 (9th Cir. 1997) (accepting supplemental affidavits in
support of petitioners’ standing, where no such requirement applied in
administrative proceedings).
12               SIERRA CLUB V. U.S. EPA

does not dispute, that “the interests at stake are germane” to
Petitioners’ organizational interests, and that personal
participation by Petitioners’ individual members is not
necessary. Id.

     The only question remaining, therefore, is whether
Petitioners’ individual members have standing in their own
right. On that score, Petitioners must first show that their
members “have suffered an injury in fact—an invasion of a
legally protected interest which is (a) concrete and
particularized, and (b) actual or imminent, not conjectural or
hypothetical.” Lujan, 504 U.S. at 560 (internal quotation
marks and citations omitted). “Second, there must be a causal
connection between the injury and the conduct complained of
. . . .” Id. (citing Simon v. E. Ky. Welfare Rights Org.,
426 U.S. 26, 41–42 (1976)). And finally, “the injury will
[likely] be redressed by a favorable decision.” Id. at 561
(internal quotation marks omitted) (citing Simon, 426 U.S. at
38, 43).

                              A

    We first consider whether Petitioners, through the
declarations of their members, have established an injury in
fact. “An individual bringing a substantive claim related to
environmental harms may establish an injury in fact by
showing ‘a connection to the area of concern sufficient to
make credible the connection that the person’s life will be
less enjoyable—that he or she really has or will suffer in his
or her degree of aesthetic or recreational satisfaction—if the
area in question remains or becomes environmentally
degraded.’” W. Watersheds Project v. Kraayenbrink,
632 F.3d 472, 484 (9th Cir. 2011) (quoting Ecol. Rights
Found. v. Pac. Lumber Co., 230 F.3d 1141, 1149 (9th Cir.
                 SIERRA CLUB V. U.S. EPA                     13

2000)). In addition, “evidence of a credible threat to the
plaintiff’s physical well-being from airborne pollutants” may
establish an injury in fact. Hall v. Norton, 266 F.3d 969, 976
(9th Cir. 2001).

    Here, although we have doubts as to the Sierra Club’s
standing, we are satisfied that Greenaction for Health and
Environmental Justice, Center for Biological Diversity, and
El Pueblo para el Aire y Agua Limpio, possess associational
standing to challenge EPA’s action.

    Marciela Mares-Alatorre, the leader of El Pueblo para el
Aire y Agua Limpio, lives in Kettleman City, which is
located approximately 10 miles from the site of the Avenal
Energy Project. She was recently diagnosed with breathing
difficulty and symptoms that indicate asthma, problems she
avers are exacerbated when the air is more polluted. She
fears that the pollution expected from the Avenal Energy
Project will impair her health. Likewise, Mavi Sandoval, a
member of El Pueblo para el Aire y Agua Limpio, as well as
Center for Biological Diversity, lives in Kettleman City,
works in Avenal, and states that she is concerned that her
respiratory problems will also be exacerbated by pollution
from the proposed plant. Maria Saucedo, a member of
Greenaction for Health and Environmental Justice, lives in
Avenal and avers that her husband and daughter suffer from
serious respiratory problems associated with air pollution.
She believes that air pollution created by the proposed facility
may further jeopardize the health of her family, and impact
her husband’s ability to work. These health threats are
credible, concrete, and, assuming the Project goes forward,
imminent—in sum, cognizable injuries in fact. Id.
14                SIERRA CLUB V. U.S. EPA

                               B

    As to causation and redressability, it is undisputed that the
Avenal Energy Project will generate many tons of air
pollutants known to threaten public health, including NO2 and
SO2. Further, EPA implemented the revised NO2 and SO2
hourly NAAQS precisely because short-term exposure to
those pollutants at ambient levels is associated with asthma
and other respiratory ailments.               See 42 U.S.C.
§ 7408(a)(1)(A) (commanding EPA Administrator to identify
and regulate “emissions which, in his judgment, cause or
contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare”); see also
Primary National Ambient Air Quality Standards for
Nitrogen Dixoide, 75 Fed. Reg. at 6,479 (concluding that
short-term exposure to ambient or near-ambient
concentrations of NO2 increased airway irritation for
asthmatic individuals), and Primary National Ambient Air
Quality Standards for Sulfur Dixoide, 75 Fed. Reg. at 35,525
(finding causal relationship between short-term exposure to
ambient NO2 and asthma and other respiratory symptoms).
EPA also noted in its Supplemental Statement of Basis that
short-term exposure to NO2 likely causes adverse effects on
the respiratory system. Given this record, we have little
trouble concluding that NO2 and SO2 emissions from the
proposed Project will likely cause the identified injuries.
Indeed, remedying such injuries is exactly the purpose and
function of these particular emissions limits, and more
broadly, the Clean Air Act. It is therefore sufficiently clear
that judicial review of EPA’s refusal to enforce the relevant
regulations will provide Petitioners’ members with redress.

   Accordingly, we conclude that at least Greenaction for
Health and Environmental Justice, Center for Biological
                  SIERRA CLUB V. U.S. EPA                       15

Diversity, and El Pueblo para el Aire y Agua Limpio, have
association standing to proceed. We need not decide whether
Sierra Club has standing. See Kaahumanu v. Hawaii,
682 F.3d 789, 798 (9th Cir. 2012) (citing Watt v. Energy
Educ. Found., 454 U.S. 151, 160 (1981) (“Because we hold
that [one plaintiff] has Article III standing, we need not reach
the question whether [another plaintiff] also has Article III
standing”).

                                II

     We now turn to the substance of Petitioners’ challenge,
that is, whether EPA exceeded its authority under the Clean
Air Act. When we review an agency’s interpretation of a
statute that it is responsible for administering, “[f]irst, always,
is the question whether Congress has directly spoken to the
precise question at issue.” Chevron, 467 U.S. at 842. “If the
intent of Congress is clear, that is the end of the matter; for
the court, as well as the agency, must give effect to the
unambiguously expressed intent of Congress.” Id. at 842–43.
Only if “the statute is silent or ambiguous,” id. at 843, “‘must
[we] decide how much weight to accord an agency’s
interpretation.’” McMaster v. United States, 731 F.3d 881,
889 (9th Cir. 2013) (quoting Tualatin Valley Builders Supply,
Inc. v. United States, 522 F.3d 937, 940 (9th Cir. 2008)).

     EPA contends there is ambiguity or tension between two
mandates in the Clean Air Act—one, requiring it to enforce
current NAAQS and BACT requirements, 42 U.S.C.
§ 7475(a)(1), (3)–(4), and the other, requiring EPA to act on
applications within one year, id. § 7475(c).               More
specifically, EPA argues that the statute does not specify what
it should do when, as was the case here, it failed to act by the
statutory deadline, and revised air standards have been
16                SIERRA CLUB V. U.S. EPA

promulgated since the deadline passed. Thus, the argument
goes, EPA’s decision to grant Avenal Power the Permit is
entitled to Chevron deference. Petitioners, on the other hand,
insist that the statutory language is clear—EPA must enforce
the regulations in effect at the time the Permit was issued.

                               A

    We begin with the statute “‘to determine whether the
language at issue has a plain and unambiguous
meaning. . . .’” Barnhart v. Sigmon Coal Co., 534 U.S. 438,
450 (2002) (quoting Robinson v. Shell Oil Co., 519 U.S. 337,
340 (1997)). In so inquiring, we must endeavor to read the
Clean Air Act “‘as a symmetrical and coherent regulatory
scheme,’” FDA v. Brown & Williamson Tobacco Corp.,
529 U.S. 120, 133 (2000) (quoting Gustafson v. Alloyd Co.,
513 U.S. 561, 569 (1995)), and “‘fit, if possible, all parts into
a harmonious whole[.]’” Id. (quoting FTC v. Mandel Bros.,
Inc., 359 U.S. 385, 389 (1959)).

      The Clean Air Act states that “[n]o major emitting facility
. . . may be constructed . . . unless”:

        (3) the owner or operator of such facility
        demonstrates, as required pursuant to section
        7410(j) of this title . . . that emissions from
        construction or operation of such facility will
        not cause, or contribute to, air pollution in
        excess of any . . . national ambient air quality
        standard in any air quality control region . . .
        [and]

        (4) the proposed facility is subject to the best
        available control technology for each
                 SIERRA CLUB V. U.S. EPA                     17

       pollutant subject to regulation under this
       chapter emitted from, or which results from,
       such facility . . . .

42 U.S.C. § 7475(a)(3)–(4) (emphasis added). The referenced
portion of § 7410(j), in turn, provides:

       As a condition for issuance of any permit
       required by this subchapter, the owner or
       operator of each new or modified stationary
       source which is required to obtain such a
       permit must show to the satisfaction of the
       permitting authority that the technological
       system of continuous emission reduction
       which is to be used at such source will enable
       it to comply with the standards of
       performance which are to apply to such
       source . . . .

Id. § 7410(j) (emphasis added). The plain language of the
statute—which prohibits the construction of any “major
emitting facility” and refers to “any . . . national ambient air
quality standard,” and “the standards of performance which
are to apply to such source[,]” as the applicable
regulations—clearly requires EPA to apply the regulations in
effect at the time of the permitting decision. 42 U.S.C.
§§ 7475(a)(4), 7410(j); see also 40 C.F.R. § 52.21(k)
(referring to “any national ambient air quality standard in any
air quality control region”).

   Up until now, there has never been any doubt that Permit
applicants must comply with current air quality control
regulations and BACT requirements. Indeed, EPA initially
advanced precisely this position against Avenal Power before
18               SIERRA CLUB V. U.S. EPA

the D.C. district court, based on the public guidance it had
previously provided in the form of the Page Memo. To wit:

       EPA generally interprets the [Clean Air Act]
       and EPA’s . . . permitting program regulations
       to require that each final . . . permit decision
       reflect consideration of any NAAQS that is in
       effect at the time the permitting authority
       issues a final permit. As a general matter,
       permitting and licensing decisions of
       regulatory agencies must reflect the law in
       effect at the time the agency makes a final
       determination on a pending application.
       [internal citations omitted]. [ ¶] Consistent
       with such interpretations, EPA has previously
       concluded that the relevant provisions cover
       any NAAQS that is in effect at the time of
       issuance of any permit.

Page Memo at 2 (emphasis added).

    EPA’s prior interpretation is supported by Supreme Court
case law. For example, in Ziffrin, Inc. v. United States,
318 U.S. 73, 78 (1943), petitioner Ziffrin Truck Lines
challenged an order by the Interstate Commerce Commission
(“ICC”) rejecting its application for a permit to continue
operating as a common carrier, in an effort to claim the
benefit of a grandfathering clause in the Interstate Commerce
Act. While Ziffrin’s application was still pending before the
ICC—after a hearing was held, but before the application was
ultimately denied—Congress amended the Interstate
Commerce Act to require a finding by the ICC that
grandfathering such a permit would serve the public interest.
Id. at 75. Applying the superseding requirement, the ICC
                  SIERRA CLUB V. U.S. EPA                   19

found grandfathering would not benefit the public, and denied
Ziffrin a permit. The Supreme Court upheld the ICC’s
decision, explaining: “We are convinced that the Commission
was required to act under the law as it existed when its order
of [denial], was entered.” Id. at 78. The Court reasoned:

        A change in the law between a nisi prius and
        an appellate decision requires the appellate
        court to apply the changed law. A fortiori, a
        change of law pending an administrative
        hearing must be followed in relation to
        permits for future acts. Otherwise the
        administrative body would issue orders
        contrary to the existing legislation.

Id. (citations omitted).

    General Motors Corp. v. United States, 496 U.S. 530, 540
(1990), also provides support for the same basic principle that
EPA is bound to enforce administrative guidelines in effect
when it takes final action. Under certain provisions of the
Clean Air Act not relevant to the present case, the states are
required to propose State Implementation Plans to implement,
maintain, and enforce NAAQS. See generally 42 U.S.C.
§ 7410(a)(1). The states also periodically revise the State
Implementation Plans, with approval from EPA, which
enforces them. Id. § 7410(a)(2)(H). In General Motors, EPA
moved to enforce certain provisions of Massachusetts’
existing State Implementation Plan. General Motors argued
that EPA lacked the authority to initiate enforcement
proceedings because, under the Administrative Procedure
Act, EPA had “unreasonably” delayed review of certain
proposed revisions to the State Implementation Plan that
would have relieved General Motors of liability. Id. at
20               SIERRA CLUB V. U.S. EPA

539–42. The Supreme Court disagreed. It held that EPA was
authorized to enforce the then-existing State Implementation
Plan regulations against General Motors, even assuming that,
but for EPA’s alleged unreasonable delay, a superseding State
Implementation Plan relieving the company of liability would
be in effect. Id. at 540. The Court noted that “[t]here is
nothing in the statute that limits EPA’s authority to enforce
the ‘applicable implementation plan’ solely to those cases
where EPA has not unreasonably delayed action on a
proposed [State Implementation Plan] revision.” Id. at 541.

     The same is true here. Nothing in the statute precludes
EPA from enforcing current NAAQS and BACT
requirements even if it unreasonably delays taking action on
a Permit. Moreover, the Clean Air Act is not silent about the
consequences of such delay. “Congress has directly spoken
to [that] precise issue”—namely, by providing a private right
of action to compel timely action. Chevron, 467 U.S. at 842
(emphasis added). Under 42 U.S.C. § 7604(a)(2):

       Except as provided in subsection (b) of this
       section, any person may commence a civil
       action on his own behalf . . . against the
       Administrator where there is alleged a failure
       of the Administrator to perform any act or
       duty under this chapter which is not
       discretionary with the Administrator.

Avenal Power, of course, availed itself of this remedy and
brought suit in the D.C. district court. That court, correctly
in our view, did not find the appropriate remedy to be
issuance of the Permit without regard to the newly-
                     SIERRA CLUB V. U.S. EPA                            21

promulgated regulations.5 Instead, it simply ordered the
agency to come to a final decision. See Avenal Power Ctr.,
LLC v. EPA, 787 F. Supp. 2d 1, 4–5 (D.D.C. 2011).

    Although EPA now maintains that, having missed the
deadline to act, it cannot determine from the statute which
substantive standards to enforce against Avenal Power, we
discern no such uncertainty, and reject the agency’s position
that it possesses the power to resolve the matter as it sees fit.
First of all, as a general matter, the agency’s “authority and
responsibility to resolve some questions left open by
Congress that arise during the law’s administration” does not
extend to “include a power to revise clear statutory terms that
turn out not to work in practice.” Utility Air Regulatory Grp.
v. EPA, No. 12-1146, — S. Ct. —, 2014 WL 2807314, at *13
(June 23, 2014) (citing Barnhart, 534 U.S. at 462). In other



 5
    We find Brock v. Pierce Cnty., 476 U.S. 253, 256 (1986), instructive
in this regard. In Brock, a since-repealed provision of the Comprehensive
Employment and Training Act required the Secretary of Labor to issue a
final determination as to the misuse of certain funds within 120 days after
receipt of a complaint alleging misuse. Id. Although the statute used
mandatory language requiring the Secretary to investigate and issue
formal findings, it did not specify consequences for the Secretary’s failure
to act. Id. at 258–59. The Court rejected the argument that the 120-day
period was a statute of limitations that barred the Secretary from taking
further action on the complaint after the 120-day period expired,
reasoning: “We would be most reluctant to conclude that every failure of
an agency to observe a procedural requirement voids subsequent agency
action, especially when important public rights are at stake.” Id. at 260.
And the Court then concluded, instead: “When, as here, there are less
drastic remedies available for failure to meet a statutory deadline, courts
should not assume that Congress intended the agency to lose its power to
act.” Id. (footnote omitted). The appropriate relief, the Court noted, was
an order compelling the agency to act. Id. at 260 n.7.
22                  SIERRA CLUB V. U.S. EPA

words, “[a]n agency confronting resource constraints may
change its own conduct, but it cannot change the law.” Id.

    Moreover, as for the particular proceedings at issue here,
we do not believe EPA’s legal or practical options were so
conflicted, or even very uncertain. Although Petitioners
suggest that EPA must deny a Permit application if it cannot
perform the required review within the one-year limit, that
does not appear to have been the agency’s only option.6 Even
after the deadline passes, at least absent suit, EPA could
presumably work with the applicant to ensure compliance
with whatever regulations are in effect, and then issue or deny
a Permit accordingly. In fact, that is what happened here:
well after the deadline passed, EPA requested, and Avenal
Power endeavored to provide, documentation demonstrating
the Avenal Energy Project’s compliance with the intervening
NO2 NAAQS. Ultimately, those efforts failed because
Avenal Power could not demonstrate compliance with the
Clean Air Act’s requirements by the date set by the D.C.
district court (a deadline imposed upon Avenal Power’s own
motion). But the parties’ protracted negotiation of the Clean
Air Act’s requirements— frustrating and burdensome though
it may have been in this case—does not endow the EPA with
authority simply to waive the newly effective regulations on
an ad hoc basis by “rewriting unambiguous statutory terms”
in order to serve its own “bureaucratic policy goals.” Id.




     6
     We need not decide whether a petitioner, other than the Permit
applicant, could sue EPA under 42 U.S.C. §§ 7604(a)(2), 7475(c), with the
ultimate effect of forcing the agency to deny, without delay, a non-
compliant Permit application.
                  SIERRA CLUB V. U.S. EPA                       23

                                B

    In an effort to bolster its position, EPA points out that it
has long exercised authority to grandfather certain permit
applications from revised regulations. That is true: EPA first
asserted grandfathering authority shortly after the 1977
Amendments to the Clean Air Act passed. The issue at that
time was a conflict between two apparently inconsistent
provisions of the Clean Air Act—§ 165’s enforcement
requirements, and § 168’s statutory grandfathering measures.
See Citizens to Save Spencer Cnty. v. EPA, 600 F.2d 844,
853–54 (D.C. Cir. 1979) (“[§] 168 would have the practical
effect of allowing permits to be issued for the construction of
many projects for which permits would be barred by the
rigorous environmental standards of [§] 165” ). EPA
ultimately chose not to make § 165 immediately effective,
and grandfathered certain projects from its requirements. See
1977 Clean Air Act Amendments to Prevent Significant
Deterioration, 43 Fed. Reg. 26,388, 26,391 (June 19, 1978)
(adopting grandfathering for new permitting requirements for
“any source the evaluation of which EPA would have
completed before March 1, 1978, but for an extension of the
public comment period pursuant to a meritorious request for
such an extension”). The D.C. Circuit upheld the agency’s
decision in an opinion rendered prior to Chevron. Id. at
881–84. But EPA’s decision, and the court’s analysis, in that
distinct statutory context does not resolve the question
presented here.7




  7
     To be clear, we do not doubt, or express any opinion on, EPA’s
traditional authority to employ formal rulemaking to implement
grandfathering.
24               SIERRA CLUB V. U.S. EPA

    Since then, EPA has invoked grandfathering authority
from time to time to exempt certain projects from newly-
implemented NAAQS and BACT regulations. But EPA’s
traditional exercise of grandfathering authority does not at all
resemble the ad hoc discretion the agency now claims to
wield. When EPA implemented grandfathering in the past,
it consistently did so through formal notice and comment
rulemaking procedures, as expressly authorized by the Clean
Air Act, 42 U.S.C. § 7601(a)(1), and the Administrative
Procedure Act, 5 U.S.C. § 553. For example, just last year,
when EPA implemented new standards for particulate matter
(“PM”), it implemented grandfathering to smooth the
transition process. As the agency explained:

       In addition to today’s revisions to the primary
       annual the PM2.5 NAAQS, EPA is taking final
       action on a PSD implementation provision.
       To facilitate timely implementation of the
       PSD requirements resulting from the revised
       NAAQS, which would otherwise become
       applicable to all PSD permit applications upon
       the effective date of this final PM NAAQS
       rule, the EPA is finalizing a grandfathering
       provision for pending permit applications.
       This final rule incorporates revisions to the
       PSD regulations that provide for
       grandfathering of PSD permit applications
       that have been determined to be complete on
       or before December 14, 2012 or for which
       public notice of a draft permit or preliminary
       determination has been published as of the
       effective date of today’s revised PM2.5
       NAAQS.
                    SIERRA CLUB V. U.S. EPA                           25

National Ambient Air Quality Standards for Particulate
Matter, 78 Fed. Reg. 3,086, 3,249 (Jan. 15, 2013).

     There is a significant difference between EPA’s
traditional grandfathering and its waiver of current applicable
regulations in this case. On almost every prior occasion, EPA
grandfathered a limited set of applications, in effect, by
specifying an operative date (or dates) for each new
regulation, as it was formally adopted.8 In contrast to the ad
hoc waiver here, the former procedure does not, on its face,
violate the plain statutory mandate to enforce whatever
regulations are in effect at the time the agency makes a final
decision. That is because, in the past, EPA simply identified
an operative date, incident to setting the new substantive
standard, and the grandfathering of pending permit
applications was explicitly built into the new regulations. See
Morton v. Ruiz, 415 U.S. 199, 231–32 (1974) (holding that
“[t]he power of an administrative agency to administer a
congressionally created and funded program necessarily
requires the formulation of policy and the making of rules to
fill any gap left, implicitly or explicitly, by Congress[,]” but
noting that “[n]o matter how rational or consistent with



  8
    See, e.g., Requirements for Preparation, Adoption, and Submittal of
Implementation Plans; Approval and Promulgation of Implementation
Plans, 45 Fed. Reg. 52,676, 52,681–83 (Aug. 7, 1980) (implementing
grandfathering provision to facilitate implementation of new definitions
of key terms and revised regulations); Regulations for Implementing
Revised Particulate Matter Standards, 52 Fed. Reg. 24,672, 24,683 (July
1, 1987) (implementing grandfathering for newly promulgated NAAQS);
Prevention of Significant Deterioration for Nitrogen Oxides, 53 Fed. Reg.
40,656, 40,659 (Oct. 17, 1988) (same); Prevention of Significant
Deterioration for Particulate Matter, 58 Fed. Reg. 31,622, 31,632–33 (June
3, 1993) (same).
26                  SIERRA CLUB V. U.S. EPA

congressional intent a particular decision might be, [such
decision] cannot be made on an ad hoc basis . . . ”).

     The issue here is distinct. EPA now claims the authority
to waive the law’s requirements at will, without regard to the
regulations it has passed,9 and without any precedential value
one way or another for future parties. That unbounded
discretion exceeds the agency’s authority. We cannot discern
any ambiguity or conflict between the Clean Air Act’s
enforcement requirements, and the statutory decision making
deadline. And the statute does not permit EPA to waive
current NAAQS and BACT requirements whenever it finds
it convenient to do so. The foregoing conclusion ends the
inquiry. Barnhart, 534 U.S. at 450; Chevron, 467 U.S. at
842–43. Congress has spoken, and at least without applicable
grandfathering provisions in the relevant regulations, EPA
must enforce the regulations in effect at the time each Permit
is issued, as the Clean Air Act clearly requires.

                                  C

    Finally, EPA relies heavily on the argument that the
equities weigh in favor of Avenal Power. In short, we agree.
Avenal Power filed its application over six years ago, and
endeavored to work with EPA for years, even after filing suit,
to obtain a final decision. But however regrettable EPA’s
treatment of Avenal Power has been, we simply cannot
disregard the plain language of the Clean Air Act, or overlook


 9
   In fact, EPA expressly refused to adopt a grandfathering provision in
connection with its promulgation of the greenhouse gases regulation at
issue in this litigation. See Reconsideration of Interpretation of
Regulations That Determine Pollutants Covered by Clean Air Act
Permitting Programs, 75 Fed. Reg. at 17,021–22.
                 SIERRA CLUB V. U.S. EPA                   27

the reason why an applicant must comply with revised and
newly stringent standards —that is, “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). Honoring the statute’s
plain language and overriding purpose, we must send EPA
and Avenal Power back to the drawing board.

                      CONCLUSION

    For the foregoing reasons, we GRANT the Petition for
review, VACATE the decision to issue the Permit, and
REMAND for proceedings consistent with this opinion.
Petitioners, as the prevailing parties, may recover the costs
and fees incurred in this litigation from EPA. 42 U.S.C.
§ 7607(f); Fed. R. App. P. 39(a)–(b).
