                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


WILDEARTH GUARDIANS, MIDWEST              No. 12-16797
ENVIRONMENTAL DEFENSE CENTER,
and SIERRA CLUB,                            D.C. No.
              Plaintiffs-Appellants,     4:11-cv-05651-
                                              YGR
                 v.

GINA MCCARTHY, in her official             OPINION
capacity as Administrator of the
Environmental Protection Agency,
               Defendant-Appellee.


     Appeal from the United States District Court
        for the Northern District of California
   Yvonne Gonzalez Rogers, District Judge, Presiding

                Argued and Submitted
      October 10, 2014—San Francisco, California

                Filed December 1, 2014

  Before: William C. Canby, Jr., William A. Fletcher,
          and Paul J. Watford, Circuit Judges.

               Opinion by Judge Watford
2          WILDEARTH GUARDIANS V. MCCARTHY

                           SUMMARY*


                       Environmental Law

    The panel affirmed the district court’s dismissal for lack
of subject matter jurisdiction of plaintiff environmental
groups’ Clear Air Act citizen-suit action seeking to require
the Environmental Protection Agency’s Administrator to
issue revised regulations governing ozone pollution.

    The Clean Air Act’s citizen-suit provision, 42 U.S.C.
§ 7604, authorizes suits against the EPA’s Administrator
only for actions where there is an alleged failure by the
Administrator to perform an act or duty which is not
discretionary with the Administrator. In 1977, Congress
added a new program to the Clean Air Act, known as the
Prevention of Significant Deterioration (PSD) program, to
prevent air quality from significantly deteriorating in areas
that already had relatively clean air. Section 166(a) of the
Clean Air Act required the EPA to issue regulations
implementing the PSD program, and plaintiffs alleged that
the Administrator had a nondiscretionary duty to issue revised
ozone regulations under § 166(a).

    The panel held that given § 166(a)’s ambiguity, the
existence of a nondiscretionary duty to promulgate revised
PSD regulations for ozone was not clear cut or readily
ascertainable from the statute. The panel concluded that this
was enough to preclude plaintiffs’ reliance on § 7604(a)(2)
as the jurisdictional basis for their suit.

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
          WILDEARTH GUARDIANS V. MCCARTHY                    3

                         COUNSEL

David Bender (argued) and Christa Westerberg, McGillivray,
Westerberg & Bender, Madison, Wisconsin; Robert Ukeiley,
Berea, Kentucky; Kristin Henry, Sierra Club, San Francisco,
California; James Jay Tutchton, WildEarth Guardians,
Centennial, Colorado, for Plaintiffs-Appellants.

Robert Lundman (argued), Ignacia Moreno, Assistant
Attorney General, Eileen McDonough, and David Gunter,
United States Department of Justice, Environment & Natural
Resources Division, Washington, D.C.; Brian Doster and
Melina Williams, Office of General Counsel, Environmental
Protection Agency, for Defendant-Appellee.


                         OPINION

WATFORD, Circuit Judge:

    Plaintiffs WildEarth Guardians, Midwest Environmental
Defense Center, and Sierra Club are organizations dedicated
to environmental conservation.           They believe the
Environmental Protection Agency (EPA) has been derelict in
its duty to protect the nation’s air from ground-level ozone
pollution. They sued the EPA’s Administrator in federal
district court, seeking an order that would force the
Administrator to issue revised regulations governing ozone
pollution.

    Plaintiffs invoked the Clean Air Act’s citizen-suit
provision, 42 U.S.C. § 7604, as the sole basis for subject
matter jurisdiction. That provision authorizes suits against
the Administrator, but only for actions “where there is alleged
4         WILDEARTH GUARDIANS V. MCCARTHY

a failure of the Administrator to perform any act or duty
under this chapter which is not discretionary with the
Administrator.” § 7604(a)(2) (emphasis added). Plaintiffs
contend the Administrator has a nondiscretionary duty to
issue revised ozone regulations under § 166(a) of the Clean
Air Act, 42 U.S.C. § 7476(a). The district court held that the
statute permits, but does not require, the Administrator to
issue such regulations and therefore dismissed plaintiffs’
claim for lack of subject matter jurisdiction. To facilitate
immediate appeal, the court granted plaintiffs’ request to
enter final judgment on that claim under Federal Rule of Civil
Procedure 54(b).

    The only issue on appeal is whether plaintiffs have
adequately alleged the violation of a nondiscretionary duty.
Before we discuss the parties’ competing interpretations of
§ 166(a), a brief summary of the relevant regulatory scheme
is necessary.

    When Congress enacted the Clean Air Act Amendments
of 1970, it required EPA to identify pollutants that “cause or
contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare.” 42 U.S.C.
§ 7408(a)(1)(A). For each such pollutant, Congress required
EPA to issue national ambient air quality standards
(NAAQS). § 7409(a)(1)(A). To oversimplify a bit, NAAQS
set limits on the permissible concentrations of regulated
pollutants in the ambient air.

    In 1971, EPA issued NAAQS for six pollutants:
particulate matter, sulfur dioxide, photochemical oxidants,
hydrocarbons, carbon monoxide, and nitrogen dioxide.
36 Fed. Reg. 8186, 8186 (Apr. 30, 1971). The term
“photochemical oxidants” includes ozone, and in 1979 EPA
          WILDEARTH GUARDIANS V. MCCARTHY                      5

formally changed the chemical designation for the relevant
NAAQS to “ozone.” 44 Fed. Reg. 8202, 8202 (Feb. 8, 1979).
For our purposes, “photochemical oxidants” and “ozone”
refer to the same thing.

    On August 7, 1977, Congress added a new program to the
Clean Air Act, known as the Prevention of Significant
Deterioration (PSD) program. Clean Air Act Amendments of
1977, Pub. L. No. 95–95, 91 Stat. 685. As its name implies,
the PSD program is designed to prevent air quality from
significantly deteriorating in areas that already have relatively
clean air. The program thus applies to “attainment” areas,
meaning areas that meet the NAAQS for a given pollutant,
and “unclassifiable” areas, meaning areas for which
insufficient data exists to determine whether the NAAQS for
a given pollutant have or have not been met. 42 U.S.C.
§ 7471; Alaska Dep’t of Envtl. Conservation v. EPA, 540 U.S.
461, 470–71 (2004).

   As part of the newly enacted PSD program, Congress
added § 166 of the Clean Air Act, the statute at issue here.
Subsection (a) requires EPA to issue regulations
implementing the PSD program. It provides in full:

        (a) Hydrocarbons, carbon monoxide,
        photochemical oxidants, and nitrogen oxides

        In the case of the pollutants hydrocarbons,
        carbon monoxide, photochemical oxidants,
        and nitrogen oxides, the Administrator shall
        conduct a study and not later than two years
        after August 7, 1977, promulgate regulations
        to prevent the significant deterioration of air
        quality which would result from the emissions
6         WILDEARTH GUARDIANS V. MCCARTHY

       of such pollutants. In the case of pollutants
       for which national ambient air quality
       standards are promulgated after August 7,
       1977, he shall promulgate such regulations
       not more than 2 years after the date of
       promulgation of such standards.

42 U.S.C. § 7476(a).

     Both the first and second sentences of this provision
unquestionably impose nondiscretionary duties on the
Administrator. The first sentence required the Administrator
to promulgate PSD regulations for the four listed pollutants
no later than August 7, 1979. The parties agree that this duty
has long since been discharged. The focus of this appeal is
therefore on the duty imposed by the second sentence. That
sentence, too, requires the Administrator to promulgate PSD
regulations, but the precise scope of the nondiscretionary duty
it imposes depends on how broadly or narrowly one interprets
the sentence.

     We’ll begin with the narrow interpretation, which is the
one EPA favors. Read together, the first and second
sentences of § 166(a) could be construed as referring to two
mutually exclusive sets of pollutants: pollutants for which
NAAQS had already been promulgated as of August 7, 1977
(first sentence), and pollutants for which NAAQS would not
be promulgated until sometime later (second sentence).
Under that reading, the second sentence would impose a
nondiscretionary duty, but a one-time duty of limited scope:
to promulgate PSD regulations within two years after
NAAQS are first issued for a newly regulated pollutant.
Since ozone is one of the already regulated pollutants covered
          WILDEARTH GUARDIANS V. MCCARTHY                    7

by the first sentence, EPA argues, the mandatory duty
imposed by the second sentence simply doesn’t apply here.

    Plaintiffs, of course, urge us to reject that reading. They
contend the second sentence should be read more broadly to
cover all pollutants. Read in that fashion, the second
sentence would impose a nondiscretionary duty to promulgate
PSD regulations not only when NAAQS are first issued for a
newly regulated pollutant, but also when NAAQS are revised
for any pollutant, including the four mentioned in the first
sentence. Because EPA revised the NAAQS for ozone on
March 27, 2008, plaintiffs argue, the agency had a
nondiscretionary duty to promulgate revised PSD regulations
for ozone within two years of that date. It is undisputed that
EPA did not do so, and in fact still has not done so.

    If our task were to decide which of these two readings of
the statute is correct, this might be a hard case, since both
appear plausible. On the one hand, the narrow reading is
plausible given the parallel structure of the first and second
sentences. The first sentence begins, “In the case of the [four
named pollutants]”; the second begins, “In the case of
pollutants for which [NAAQS] are promulgated after August
7, 1977. . . .” The repeated use of the phrase “In the case of”
suggests that the drafters intended the first sentence to
address one set of circumstances and the second sentence to
address another. That inference is strengthened by the fact
that, as of August 7, 1977, the only pollutants then subject to
NAAQS for which PSD regulations would be required were
the four listed in the first sentence. (There were two
additional pollutants for which NAAQS had already been
issued—particulate matter and sulfur dioxide—but EPA
didn’t need to promulgate PSD regulations for them because
Congress itself had established the initial PSD requirements
8         WILDEARTH GUARDIANS V. MCCARTHY

in a separate statutory provision. See 42 U.S.C. § 7473.) It’s
thus easy to see why those drafting the statute in 1977 might
have used the phrase “pollutants for which [NAAQS] are
promulgated after August 7, 1977” to distinguish the set of
as-yet-unregulated pollutants covered by the second sentence
from the distinct set of already regulated pollutants covered
by the first. While the text might have been clearer had the
second sentence referred to “other pollutants not covered by
the first sentence,” or “pollutants for which NAAQS are first
promulgated after August 7, 1977,” the drafters could have
understood the language they chose as already drawing that
distinction.

    On the other hand, plaintiffs’ broad reading of the second
sentence—as encompassing all pollutants and imposing a
mandatory duty to revise the PSD regulations each time the
NAAQS are revised—is plausible as well. As plaintiffs point
out, it would have been sensible for Congress to conclude that
whenever the NAAQS for a given pollutant are revised, the
corresponding PSD regulations should be revised too, since
new information that justifies revisions to the NAAQS would
likely justify revisions to the PSD requirements. (EPA has
historically calculated PSD requirements by calibrating them
to the NAAQS governing each pollutant. See 75 Fed. Reg.
64,864-01, 64,869 (Oct. 20, 2010).) But even if Congress
held that view, it doesn’t strike us as irrational or absurd, as
plaintiffs suggest, for Congress to have created a regulatory
scheme predicated on the narrow reading of § 166(a).
Congress could have been content to kick-start the PSD
program by mandating EPA’s promulgation of initial PSD
regulations, but then have left to the agency’s discretion the
responsibility for making whatever revisions to those
regulations might be warranted when the corresponding
NAAQS were revised.
          WILDEARTH GUARDIANS V. MCCARTHY                    9

    In the end, we don’t have to decide which of these
conflicting interpretations of § 166(a) is correct, because our
cases have adopted what amounts to a clear statement rule in
this context. When a plaintiff sues the EPA Administrator for
failure “to perform any act or duty under this chapter which
is not discretionary with the Administrator,” 42 U.S.C.
§ 7604(a)(2), we have held that the nondiscretionary nature
of the duty must be clear-cut—that is, readily ascertainable
from the statute allegedly giving rise to the duty. Our
Children’s Earth Found. v. EPA, 527 F.3d 842, 851 (9th Cir.
2008) (interpreting the Clean Water Act’s similar citizen-suit
provision); see also Farmers Union Cent. Exch., Inc. v.
Thomas, 881 F.2d 757, 760 (9th Cir. 1989). We must be able
to identify a “specific, unequivocal command” from the text
of the statute at issue using traditional tools of statutory
interpretation; it’s not enough that such a command could be
teased out “from an amalgamation of disputed statutory
provisions and legislative history coupled with the EPA’s
own earlier interpretation.” Our Children’s Earth, 527 F.3d
at 851 (internal quotation marks omitted).

    Given § 166(a)’s ambiguity, we cannot say that the
existence of a nondiscretionary duty to promulgate revised
PSD regulations for ozone is clear-cut or readily ascertainable
from the statute. That is enough to preclude plaintiffs’
reliance on § 7604(a)(2) as the jurisdictional basis for their
suit. The district court therefore correctly dismissed
plaintiffs’ claim under the Clean Air Act’s citizen-suit
provision for lack of subject matter jurisdiction.

   AFFIRMED.
