                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

NATURAL RESOURCES DEFENSE               
COUNCIL; WATERKEEPER ALLIANCE,
                Plaintiffs-Appellees,
                 and
STATE OF CONNECTICUT; NEW YORK
STATE DEPARTMENT OF
ENVIRONMENTAL CONSERVATION;
STATE OF NEW YORK,                           Nos. 07-55183
   Plaintiffs-intervenors-Appellees,              07-55261
                  v.                           D.C. No.
UNITED STATES ENVIRONMENTAL                 CV-04-08307-GHK
PROTECTION AGENCY; STEPHEN L.                   OPINION
JOHNSON,
             Defendants-Appellants,
                 and
NATIONAL ASSOCIATION OF HOME
BUILDERS; ASSOCIATED GENERAL
CONTRACTORS OF AMERICA,
 Defendants-intervenors-Appellants.
                                        
        Appeal from the United States District Court
           for the Central District of California
         George H. King, District Judge, Presiding

                   Argued and Submitted
            July 17, 2008—Pasadena, California

                  Filed September 18, 2008

  Before: Barry G. Silverman, Johnnie B. Rawlinson, and
           Milan D. Smith, Jr., Circuit Judges.

                            13145
13146             NRDC v. USEPA
        Opinion by Judge Milan D. Smith, Jr.
                     NRDC v. USEPA                  13149


                       COUNSEL

Robert Lundman, United States Department of Justice, Wash-
ington, D.C., for the defendants-appellants.

Jeffrey Longworth, Barnes & Thornburg LLP, Washington,
D.C., for the defendants-intervenors-appellants.

Kim Landsman, Patterson Belknap Webb & Tyler LLP, New
York, New York, & Melanie Shepherdson, National
Resources Defense Council, Washington, D.C., for the
plaintiffs-appellees.

Douglas P. Carstens, Chatten Brown & Carstens, Santa Mon-
ica, California, & Richard Dearing, State of New York, New
York, New York, for the plaintiffs-intervenors-appellees.


                       OPINION

MILAN D. SMITH, JR., Circuit Judge:

  Plaintiffs-Appellees, National Resources Defense Council
(NRDC) and Waterkeeper Alliance Inc. (collectively,
NRDC), sued Defendants-Appellants, the United States Envi-
13150                      NRDC v. USEPA
ronmental Protection Agency and its administrator (collec-
tively, EPA), under the Clean Water Act (CWA) and the
Administrative Procedure Act (APA), seeking to compel the
EPA to promulgate effluent limitation guidelines (ELGs) and
new source performance standards (NSPSs) for storm water
pollution discharges caused by the construction and develop-
ment industry (construction industry). The States of Connecti-
cut and New York, and the New York State Department of
Environmental Conservation (collectively, state-intervenors)
intervened on behalf of NRDC; the National Association of
Home Builders and Associated General Contractors of Amer-
ica (collectively, industry-intervenors) intervened on behalf of
the EPA.

   The district court exercised its jurisdiction under the Clean
Water Act’s citizen-suit provision, CWA § 505(a)(2), 33
U.S.C. § 1365(a)(2),1 denied Defendants’ motion to dismiss,
granted Plaintiffs partial summary judgment on their claim
that the CWA requires the EPA to issue ELGs and NSPSs for
the construction industry, and issued a permanent injunction
compelling the EPA to do so.2 We have jurisdiction to review
these decisions under 28 U.S.C. §§ 1291 and 1292(a), and we
affirm.

                          BACKGROUND

  A.    Statutory Background

  Congress enacted the CWA “to restore and maintain the
chemical, physical, and biological integrity of the Nation’s
  1
     We cite to the original Act throughout this opinion, and provide a par-
allel cite to the U.S. Code only the first time we cite each CWA provision.
See Our Children’s Earth Found. v. EPA, 527 F.3d 842, 845 n.1 (9th Cir.
2008) [hereinafter OCEF].
   2
     As used throughout this opinion, the term “Defendants” refers to the
EPA and industry-intervenors. The term “Plaintiffs” refers to NRDC and
state-intervenors.
                       NRDC v. USEPA                       13151
waters.” 33 U.S.C. § 1251(a). In furtherance of the CWA’s
objective of eliminating the “discharge of pollutants into the
navigable waters,” id., the Act prohibits the “discharge of any
pollutant.” CWA § 301(a), 33 U.S.C. § 1311(a). The CWA
defines the “discharge of a pollutant” as “any addition of any
pollutant to navigable waters from any point source.” CWA
§ 502(12), 33 U.S.C. § 1362(12). A “point source” is “any
discernable, confined and discrete conveyance, including but
not limited to[,] any pipe, ditch, channel . . . from which pol-
lutants are or may be discharged.” CWA § 502(14).

   Despite § 301(a)’s general prohibition on the discharge of
pollutants, the CWA also establishes a permit system that
authorizes the discharge of some pollutants—the National
Pollutant Discharge Elimination System (NPDES). See CWA
§ 402, 33 U.S.C. § 1342. Under the NPDES, the EPA and
approved states may issue permits for the discharge of pollu-
tants that meet certain requirements outlined in § 402. Taken
together, §§ 301(a) and 402 “ ‘prohibit[ ] the discharge of any
pollutant from a point source into navigable waters of the
United States without an NPDES permit.’ ” N.W. Envt’l Advo-
cates v. EPA, __ F.3d __, Nos. 03-74795, 06-17187, 06-
17188, 2008 WL 2813103, at *1 (9th Cir. July 23, 2008)
(quoting N. Plains Res. Council v. Fidelity Exploration &
Dev. Co., 325 F.3d 1155, 1160 (9th Cir. 2003)).

   NPDES permits “place limits on the type and quantity of
pollutants that can be released into the Nation’s waters,” S.
Fla. Water Mgmt. Dist. v. Miccosukee Tribe of Indians, 541
U.S. 95, 102 (2004), and must set forth “effluent limitations,”
OCEF, 527 F.3d at 848. “Effluent limitations” are “restric-
tion[s] . . . on [the] quantit[y], rates, and concentration[ ] of
chemical, physical, biological, and other constituents which
are discharged from point sources into navigable waters.”
CWA § 502(11).

  The specific effluent limitations in an NPDES permit are
determined according to the more general ELGs and NSPSs,
13152                  NRDC v. USEPA
guidelines that are separately promulgated by the EPA. CWA
§ 304(b), 33 U.S.C. § 1314(b); CWA § 306(b), 33 U.S.C.
§ 1316(b); E.I. duPont de Nemours & Co. v. Train, 430 U.S.
112, 116-17 (1977). ELGs are technology-based restrictions
on water pollution that apply to sources of pollution already
in existence, see CWA § 304(b); NSPSs are technology-based
restrictions that apply to “new sources” of pollution. CWA
§ 306(a)(2). “A technology-based approach to water quality
focuses on the achievable level of pollutant reduction given
current technology.” OCEF, 527 F.3d at 845; see also
Waterkeeper Alliance, Inc. v. EPA, 399 F.3d 486, 491-92 (2d
Cir. 2005) (stating that ELGSs and NSPSs “are technology-
based, because they are established in accordance with vari-
ous technological standards that the Act statutorily provides”
—for example, “the best available technology economically
achievable” or “the best conventional pollutant control
technology”—and that these standards “vary depending upon
the type of pollutant involved, the type of discharge involved,
and whether the point source in question is new or already
existing”).

   Section 304(m) provides that, every two years, the EPA
“shall publish in the Federal Register a plan which shall . . .
identify categories of sources discharging toxic or nonconven-
tional pollutants” for which ELGs and NSPSs have not yet
been published, and “establish a schedule for promulgation of
effluent guidelines for categories identified.” Under this
schedule, the “promulgation of [these] guidelines shall be no
later than . . . 3 years after the publication of the plan.” Id.
ELGs and NSPSs are relevant to this appeal because the
Plaintiffs claim that the EPA violated a non-discretionary duty
to promulgate ELGs and NSPSs for the construction industry
after it was listed as a point-source category in a plan devel-
oped under § 304(m).

  B.    Administrative Proceedings

   In March 1999, the EPA announced that it was undertaking
rulemaking to address pollution from storm water discharge
                       NRDC v. USEPA                       13153
associated with construction activities, “specifically for new
development, as well as to those associated with re-
development activities.” 64 Fed. Reg. 15,158, 15,158 (March
30, 1999). In its public notice, the EPA stated that it “chose
to begin development of [ELGs] for the construction and
development industry[, in relevant part,] to support applicable
state and local requirements for erosion and sediment controls
and storm water best management practices,” because “[s]tate
and local requirements vary widely [and] [s]ediment loadings
from construction site discharges can be orders of magnitude
higher than those associated with discharges from undisturbed
areas,” and also because “construction site runoff can contrib-
ute high loadings of nutrients and metals to receiving
streams.” Id. In 2000, the EPA published its final notice of an
effluent guidelines plan, which listed construction activities as
a point-source category requiring guidelines under § 304(m).
65 Fed. Reg. 53,008, 53,011 (Aug. 31, 2000).

   On June 24, 2002, the EPA issued a proposed rule to
address storm water discharge from construction sites. 67 Fed.
Reg. 42,644, 42,644 (June 24, 2002). The EPA did not set
forth a single proposed rule, but described three “options” it
was considering. “Option 1” was to establish “minimum
requirements for conducting site inspections and providing
certification as to design and completion of controls required
by” the authority issuing NPDES permits. Id. at 42,646. “Op-
tion 2” would establish ELGs as well as the minimum require-
ments comprising Option 1. Id. “Option 3” would establish
“no new requirements,” and “[b]oth the control requirements
and the certification requirements would be left to the best
professional judgment of the permitting authority.” Id.

   On April 26, 2004, the EPA published its final action under
the caption “Proposed Rule: Withdrawal.” 69 Fed. Reg.
22,472, 22,472 (April 26, 2004). The EPA stated: “[t]his
action withdraws the proposed [ELGs and NSPSs] that EPA
proposed for the construction and development industry” on
June 24, 2002. Id. at 22,473. It further stated, “[w]e have
13154                  NRDC v. USEPA
decided not to promulgate [ELGs] and standards for the con-
struction and development industry and instead have selected
the option [Option 3] that relies on the range of existing pro-
grams, regulations, and initiatives at the Federal, State, and
local level for the control of storm water runoff from con-
struction sites.” Id. at 22,477.

   The EPA explained its decision “not to promulgate [ELGs]
and standards” by stating that it believed that construction site
storm water discharges were already “being adequately
addressed” because the “existing NPDES” regulations require
permits for the vast majority of construction sites nationwide,
and that the cost was “simply too high and . . . disproportion-
ately large” given the reductions that would be attributable to
the proposed ELGs. Id. The EPA had determined that the
annual cost of the proposed ELGs would be more than half a
billion dollars and would result in the displacement of a num-
ber of jobs while the existing permit programs were capable
of controlling 80-90% of sediment runoff from construction
sites and the proposed rule would only remove an additional
1% more. Id. The EPA also “decided not to promulgate
NSPS[s] because . . . discharges associated with construction
activity generally are not appropriately characterized as ‘new
sources,’ ” and the EPA believed that the definition of “new
source” should be read to exclude construction sites. Id. at
22,480 (“To include construction activity itself within the def-
inition of a ‘new source’ would be to view construction sites
as things that are themselves constructed.”).

  In subsequent years, the EPA removed the construction
industry from plans it published under § 304(m). See 69 Fed.
Reg. 53,705 (Sept. 2, 2004); 71 Fed. Reg. 76,644 (Dec. 21,
2006). In its 2004 plan, the EPA stated:

    [T]he analysis under CWA section 304(m)(1)(B)
    applies only to industrial categories of sources that
    are discharging non-trivial amounts of toxic or non-
    conventional pollutants to waters of the United
                        NRDC v. USEPA                       13155
      States. EPA did not consider, under this analysis,
      industrial activities where conventional pollutants,
      rather than toxic or non-conventional pollutants, are
      the pollutants of concern. For example, although
      EPA had identified stormwater discharges from [the
      construction industry] as a new category in its 2000
      and 2002 effluent guidelines program plans, EPA is
      not identifying [the construction industry] in this
      2004 plan based on new information that discharges
      from this activity consist predominately of conven-
      tional pollutants under CWA § 304(a)(4), in this case
      total suspended solids.

69 Fed. Reg. at 53,718. In its 2006 plan, EPA similarly stated
that it “did not identify . . . the construction industry because
its discharges consist almost entirely of conventional pollu-
tants,” and that the “EPA mistakenly identified this industry
under section 304(m)(1)(B) in the 2002 plan, not realizing
that its discharge” was so composed. 71 Fed. Reg. at 76,664-
65. According to the EPA, it corrected its mistake by remov-
ing the industry from its 2004 plan. Id.

  C.    District Court Proceedings

   NRDC and the state-intervenors brought this suit to chal-
lenge the EPA’s decision not to issue ELGs and NSPSs for
the construction industry after it had listed the industry in a
plan it issued under § 304(m). The EPA and the industry-
intervenors moved to dismiss, claiming that this court, not the
district court, had original jurisdiction pursuant to
§ 509(b)(1)(E), 33 U.S.C. § 1369(b)(1)(E), that the Plaintiffs
lacked standing to sue, and that certain claims were precluded.3
The district court denied the motion to dismiss.
  3
   The Defendants have abandoned their claim preclusion argument on
appeal.
13156                  NRDC v. USEPA
   The district court granted the Plaintiffs’ motion for partial
summary judgment on the basis that the EPA failed to comply
with the CWA by not performing its non-discretionary duty
to promulgate ELGs and NSPSs for the construction industry.
The district court issued a permanent injunction requiring the
EPA to issue ELGs and NSPSs for the construction industry
no later than December 1, 2009. Defendants now appeal these
rulings.

                        DISCUSSION

  A.     District Court’s Original Jurisdiction

    1.    Standard of Review

   We review a district court’s assumption of jurisdiction de
novo. United States v. Bennett, 147 F.3d 912, 913 (9th Cir.
1998). We also review a district court’s interpretation of the
CWA de novo. League of Wilderness Defenders/Blue Moun-
tains Biodiversity Project v. Forsgren, 309 F.3d 1181, 1183
(9th Cir. 2002).

    2.    Analysis

   [1] CWA § 505(a)(2) grants the district court jurisdiction
over suits “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 Administra-
tor.” Section 505(a)(2) is an exclusive grant of original juris-
diction to the district courts. Trustees for Alaska v. EPA, 749
F.2d 549, 558 (9th Cir. 1984). CWA § 509(b)(1)(E) grants the
courts of appeal jurisdiction to “[r]eview . . . the Administra-
tor’s action . . . in approving or promulgating any effluent
limitation or other limitation under section 1311, 1312, 1316,
or 1345 of this title.” Section 509(b)(1)(E) is an exclusive
grant of original jurisdiction to the courts of appeal. OCEF,
527 F.3d at 847 (referring to § 509(b)(1) as “the circuit
court’s exclusive jurisdiction”); Maier v. EPA, 114 F.3d 1032,
                           NRDC v. USEPA                            13157
1037 (10th Cir. 1997) (calling the court of appeals’ jurisdic-
tion under § 509(b)(1) “exclusive”). However, we have cau-
tioned that our jurisdiction under § 509(b)(1) is not to be
construed expansively, particularly given the “specificity and
precision” that Congress used in identifying the actions that
fall under § 509(b)(1). N.W. Envt’l Advocates, 2008 WL
2813101, at *6.

   [2] Defendants argue that the district court erred in exercis-
ing jurisdiction under § 505(a)(2), and that this court has
exclusive original jurisdiction over Plaintiffs’ claim that the
EPA violated its non-discretionary duty to promulgate ELGs
and NSPSs under § 509(b)(1)(E).4 Plaintiffs argue that the dis-
trict court properly exercised its jurisdiction. We agree with
Plaintiffs, and we hold that where a plaintiff alleges that the
EPA has failed to perform a non-discretionary duty under the
CWA and the plaintiff does not challenge the substance of
any existing regulations, the district courts have exclusive
jurisdiction under § 505(a)(2).

   In Trustees for Alaska, the NRDC alleged a failure by the
EPA “to comply with a nondiscretionary duty to promulgate
industry-wide rules.” 749 F.2d at 558. We concluded that the
district court had exclusive jurisdiction over the action under
§ 505(a)(2), stating that where a plaintiff alleges a failure by
the EPA “to perform any act or duty under the [CWA] which
is not discretionary,” the federal district courts have exclusive
jurisdiction. Id. (quoting CWA § 505(a)(2)). Here, as in Trust-
ees for Alaska, the Plaintiffs have alleged a failure by the
Administrator to perform a non-discretionary duty. Cf. id.
(“[T]he EPA has not yet promulgated regulations [establish-
ing ELGs] governing the placer miner industry.”).
  4
   For analytical purposes in determining whether the district court or the
court of appeals has original jurisdiction, we assume, as Plaintiffs claim,
that the EPA’s duty to promulgate ELGs and NSPSs is not discretionary.
We reach the merits of whether the EPA’s duty is discretionary in Section
C, infra.
13158                   NRDC v. USEPA
   We acknowledge that the underlying facts in Trustees for
Alaska differ slightly from the facts of this case. Though the
EPA did not promulgate ELGs for the relevant industry in
either case, in Trustees for Alaska, the agency had not
undertaken a rulemaking or any other procedural step towards
promulgating ELGs. In contrast, here, the EPA gave notice
and provided comment periods and proposed three “options”
before choosing not to promulgate ELGs and NSPSs related
to storm water runoff from construction sites. And, as a result
of its rulemaking, the EPA made an affirmative choice to
“rel[y] on the range of existing programs, regulations, and ini-
tiatives at the Federal, State, and local level for the control of
storm water runoff from construction sites.” 69 Fed. Reg. at
22,477.

   This distinction does not affect our jurisdictional analysis,
however, because Plaintiffs do not challenge the substance of
any of these existing programs or regulations. Plaintiffs do not
discuss the substance of any existing regulations or express
any opinion concerning the existing regulations. Thus, just
like the plaintiffs in Trustees for Alaska, Plaintiffs here are
concerned exclusively with the EPA’s failure to promulgate
certain guidelines. Such an action falls squarely within the
district court’s jurisdiction. Trustees for Alaska, 749 F.2d at
558; see CWA § 505(a)(2) (granting the district court jurisdic-
tion over suits “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”).

   Indeed, the fact that Plaintiffs do not challenge the sub-
stance of any existing regulations is precisely why
§ 509(b)(1)(E) is inapplicable. Section 509(b)(1)(E) grants the
court of appeals jurisdiction to “[r]eview . . . the Administra-
tor’s action . . . in approving or promulgating any effluent
limitation or other limitation under section 1311, 1312, 1316,
or 1345 of this title.” Even if, as Defendants argue, we could
construe the EPA’s decision to rely on existing regulations as
                        NRDC v. USEPA                       13159
an “approval” of an “other limitation” under one of the enu-
merated sections, this is insufficient to bring Plaintiffs’ claim
within § 509(b)(1)(E). This is so because Plaintiffs do not
seek a review of the existing regulations that the Administra-
tor is alleged to have “approved.”

   [3] To the extent any doubt remains about whether the dis-
trict court had original jurisdiction over Plaintiffs’ claim, it is
easily resolved by our recent decision in Our Children’s
Earth Foundation. In OCEF, environmental groups contended
that the EPA “failed to fulfill its mandate to review effluent
guidelines and limitations in a timely manner and in accord
with technology-based standards.” 527 F.3d at 844. The court
affirmed the district court’s exercise of jurisdiction under
§ 505(a)(2), stating that this court’s exclusive jurisdiction
under § 509(b)(1) “extends only to a substantive review of the
appropriateness of the guidelines actually promulgated, and
not to the threshold question of whether the statutory require-
ments of the CWA have been met.” Id. at 847 (emphasis
added); see also N.W. Envt’l Advocates, 2008 WL 2813103,
at *7 (“Section 509(b)(1)(E) authorizes original court of
appeals jurisdiction for challenges to regulations that establish
numerical limitations and similar limits.”). Because Plaintiffs
never requested such a substantive review, but rather asked
the district court to answer the “threshold question of whether
the statutory requirements of the CWA [were] met” with
respect to regulating storm water runoff from construction
activities, OCEF confirms that the district court’s exercise of
jurisdiction under § 505(a)(2) was proper. 527 F.3d at 847.

   This case differs from the Tenth’s Circuit’s decision in
Maier precisely because Plaintiffs are not requesting a review
of existing regulations. In Maier, the court held that it had
jurisdiction under § 509(b)(1)(E) to hear a challenge to the
EPA’s denial of a petition requesting that the EPA initiate a
rulemaking on certain CWA regulations. 114 F.3d at 1038. At
first glance, Maier bears some similarity to this case because
the plaintiff in Maier challenged the EPA’s choice not to take
13160                  NRDC v. USEPA
a certain action. See id. at 1036. In Maier, however, as a part
of his challenge, the plaintiff argued that “the existing regula-
tions . . . were inadequate.” Id. The Maier court noted that it
had “no difficulty construing [the suit] as a challenge to an
‘action in approving or promulgating’ ” under § 509(b)(1)(E)
because the plaintiff was “essentially challenging the suffi-
ciency of the EPA’s secondary treatment regulation.” Id. at
1038. Indeed, the court specified that “[w]here petitioners’
challenge is to the substance of a regulation that the agency
has already promulgated, exclusive jurisdiction in the court
of appeals may not be evaded merely by styling the claim as
one for failure to revise.” Id. (emphasis added). Moreover, the
Maeir court went on to distinguish the case before it from
Trustees for Alaska and other cases, like this case, where “the
EPA had failed to issue the disputed regulations at all.” Id. at
1039.

   Pennsylvania Department of Environmental Resources v.
EPA, 618 F.2d 991 (3d Cir. 1980), also supports our analysis.
That case involved the EPA’s promulgation of NSPSs for the
coal mining industry. Id. at 993. The EPA had added the coal
mining industry as a new category of point sources and pro-
mulgated regulations; but, for certain water polluting dis-
charges, the regulations issued merely deferred the
promulgation of regulations. Id. at 993-94. Noting that the
plaintiffs were seeking to compel the EPA to perform a non-
discretionary duty to promulgate NSPSs, the court concluded
that the suit should have been brought in district court under
§ 505(a)(2). Id. at 995.

   [4] Significantly, the Third Circuit noted that in cases
where the courts of appeal have jurisdiction to review a fail-
ure to act under § 509, the review focuses on the substance or
effect of promulgated regulations and not “a petitioner’s
request that the EPA be ordered to promulgate new or differ-
ent regulations.” Id. at 996. We agree with the Third Circuit
that “an allegation of inadequacy of a set of regulations is
quite different from” what Plaintiffs’ allege here—“that a
                           NRDC v. USEPA                        13161
needed regulation was nonexistent.” Id. We therefore hold
that the district court properly exercised its jurisdiction over
Plaintiffs’ claim that the EPA had violated its non-
discretionary duty to promulgate ELGs and NSPSs for the
construction industry under § 505(a)(2).

  B.       Standing

      1.        Standard of Review

  We review a district court’s determination of standing de
novo. Buono v. Norton, 371 F.3d 543, 545 (9th Cir. 2004).

      2.        Analysis

           a.     Environmental-Group Plaintiffs

   Organizations have standing to sue on behalf of their mem-
bers when: “(a) [the] members would otherwise have standing
to sue in their own right; (b) the interests [the organization]
seeks to protect are germane to the organization’s purposes;
and (c) neither the claim asserted nor the relief requested
requires the participation of individual members in the law-
suit.” Ecological Rights Found. v. Pac. Lumber Co., 230 F.3d
1141, 1147 (9th Cir. 2000) (internal quotation marks and cita-
tions omitted). The industry-intervenors challenge only
whether the members of the environmental-group Plaintiffs
(NRDC and Waterkeeper Alliance) have standing to sue in
their own right under Article III.5 We conclude that they do.

   [5] To meet Article III’s standing requirements, the party
invoking federal jurisdiction bears the burden to show that it
has: (1) “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”;
(2) that the injury is “fairly trace[able] to the challenged
  5
   The EPA has not argued that any Plaintiff lacks standing on appeal.
13162                  NRDC v. USEPA
action of the defendant”; and (3) that it is “likely, as opposed
to merely speculative, that the injury will be redressed by a
favorable decision.” Lujan v. Defenders of Wildlife, 504 U.S.
555, 560-61 (1992) (internal quotation marks and citations
omitted). In addition to these Article III standing require-
ments, our exercise of jurisdiction is also limited by pruden-
tial considerations. Bennett v. Spear, 520 U.S. 154, 162
(1997). One such consideration is whether a plaintiff’s griev-
ances “arguably fall within the zone of interests protected or
regulated by the statutory provision . . . invoked in the suit.”
Id. Section 505(a)(2) of the CWA is, however, a citizen-suit
provision that “extends standing to the outer boundaries . . .
of Article III.” Ecological Rights Found., 230 F.3d at 1147
(citing Middlesex County Sewerage Auth. v. Nat’l Sea Clam-
mers Ass’n, 453 U.S. 1, 16 (1981)). As a result, we need not
consider whether Plaintiffs have prudential standing in this
case.

   We turn first to whether the members of the environmental-
group Plaintiffs have suffered an injury in fact. “The ‘injury
in fact’ requirement in environmental cases is satisfied if an
individual adequately shows that she has an aesthetic or recre-
ational interest in a particular place, or animal, or plant spe-
cies and that that interest is impaired by a defendant’s
conduct.” Id.; see also Ocean Advocates v. U.S. Army Corps
of Eng’rs, 402 F.3d 846, 859-60 (9th Cir. 2005) (stating that
injury in fact requires an individual to show “a connection to
the area of concern sufficient to make credible the contention
that the person’s future life will be less enjoyable . . . if the
area in question remains or becomes environmentally degrad-
ed”) (internal quotation marks and citation omitted). The
injury to the plaintiff, not to the environment, is the relevant
showing. Friends of the Earth, Inc. v. Laidlaw Envtl. Servs.,
Inc., 528 U.S. 167, 181 (2000).

   [6] Members of the NRDC and Waterkeeper Alliance have
submitted several declarations averring that they have suf-
fered an injury in fact. These declarations state that the mem-
                            NRDC v. USEPA                            13163
bers have, for years, used particular waterways for aesthetic
and recreational purposes. They also state that the individuals’
use and enjoyment of those waterways has been diminished
due to storm water discharge from construction sites, and
many declarations describe having observed storm water dis-
charge flowing directly from construction sites into the water-
ways the members use. The Supreme Court found similar
evidence sufficient to establish injury in fact in Friends of the
Earth. In that case, the Court concluded that the environmen-
tal group members established injury in fact where their “rea-
sonable concerns about the effects of [Laidlaw’s discharges],
directly affected [their] recreational, aesthetic, and economic
interests.” Friends of the Earth, 528 U.S. at 183-84. Similarly,
here, the members’ statements that their use of specific water-
ways has been diminished due to their concerns about dis-
charge from a particular source (here, the construction sites)
are sufficient to establish injury in fact.

   [7] Industry-intervenors also argue that the members of the
environmental-group Plaintiffs cannot show that their injury
is “fairly trace[able] to the challenged action of the defen-
dant” or “redressable” by the relief they request—i.e., the
EPA’s promulgation of ELGs and NSPSs. Lujan, 504 U.S. at
560-61. These factors, both of which address “causation,” are
closely related and we discuss them together. See Allen v.
Wright, 468 U.S. 737, 753 n.19 (1984) (noting that the
“traceability” and “redressability” requirements of Article III
standing are closely related).

   [8] At the outset of this analysis, we observe that Plaintiffs’
showing on these two factors—whether their injuries are
“traceable” to the EPA’s failure to promulgate ELGs and
NSPSs and would be “redressed” by the EPA’s promulgation
of ELGs and NSPSs—cannot be entirely precise absent
knowledge of the substance of the regulations that the EPA
would promulgate if required to do so.6 As the district court
  6
   Though Plaintiffs do not claim that the EPA denied them any proce-
dure to which they were entitled, their suit is nevertheless similar to suits
13164                       NRDC v. USEPA
noted, to require a precise showing “would mean that no
plaintiff would have standing to bring such a suit, as one can-
not demonstrate the efficacy of regulations that have yet to be
issued.” Thus, Plaintiffs can satisfy the “traceability” and “re-
dressability” factors by showing that the type of storm water
discharge causing their injury is that which ELGs and NSPSs
aim to address, and that ELGs and NSPSs are likely to reduce
the risk of the pollution causing their injury. See Ecological
Rights Found., 230 F.3d at 1152 n.12 (acknowledging that the
CWA’s rules are “designed to reduce the risk of pollution”).
Plaintiffs have made this showing.

   [9] First, the members’ declarations support that the pollu-
tion they complain of is that which ELGs and NSPSs aim to
address. The members’ declarations support that storm water
discharge flows from active construction sites into the bodies
of water they use and enjoy, and that the storm water runoff
they complain of is polluting and diminishing the quality of
the bodies of water they use. See, e.g., Anna E. Slawsky Decl.
¶ 8 (“I have personally seen sediment run off from a 2-acre

where the plaintiff claims such a procedural injury. The Supreme Court
has noted that suits to force an agency to engage in a procedure do not
require the same certainty that the result of that procedure will have the
desired effect. See Massachusetts v. EPA, 127 S. Ct. 1438, 1453 (2007)
(citing Lujan, 504 U.S. at 572 n.7). A party can therefore enforce a proce-
dural right “so long as the procedures in question are designed to protect
some threatened concrete interest of [theirs] that is the ultimate basis of
[their] standing.” Lujan, 504 U.S. at 573 n.8; see also Massachusetts v.
EPA, 127 S. Ct. at 1453 (stating that a litigant vested with a procedural
right “has standing if there is some possibility that the requested relief will
prompt the injury-causing party to reconsider the decision” alleged to have
harmed the litigant); see also Nat’l Wildlife Fed’n v. Hodel, 839 F.2d 694,
705-06 (D.C. Cir. 1988) (“We note, however, that a party seeking judicial
relief need not show to a certainty that a favorable decision will redress
his injury. A mere likelihood will do.”) (citations omitted). The Plaintiffs
here meet this standard: the relief they call for is designed to protect the
Nation’s waterways, and it is their diminishing ability to use and enjoy
these waterways that is the ultimate basis of their standing.
                       NRDC v. USEPA                       13165
construction site and a 33-acre construction site (Puppy Creek
runs brown from this site) in Lowell during rains and the ero-
sion along Route 74 mentioned above.”); Michael Mullen
Decl. ¶ 17 (“[B]eginning in 2000 until the present day, I have
conducted inspections of the Prospect Ridge Subdivision
Extension in Troy, Alabama. . . . A number of my inspections
at Prospect Ridge were made during or just following rain
events. During my inspections I witnessed runoff with very
high turbidity and excessive amounts of sediment entering
streets and subsequently storm drains or unnamed tributaries
to Big Creek.”); Don McEnhill Decl. ¶ 15 (“I have personally
witnessed construction activities causing major discharges of
pollutants, including sediment, and documented well over
two-dozen construction sites releasing pollutants into the Rus-
sian River watershed.”); id. ¶ 24 (“During the rain season of
2003-2004, I conducted several site visits at the Vintage
Greens subdivision development in Windsor, California. I
was interested in [this] development because it was a large
development and stormwater discharged . . . would flow into
the Windsor Creek and then to the Russian River. During my
visits I witnessed constant stormwater flows containing sedi-
ment from the construction site . . . brown in color and very
turbid.”); Constance Powell Decl. ¶¶ 6-7 (“Construction and
development is continuing . . . I have personally seen sedi-
ment run off from construction sites flow directly to Lake
Johnson.”). In one declaration, Michael Mullen, the Choc-
tawhatchee Riverkeeper and the Director of the Center for
Environmental Research and Service at Troy University,
described how he sampled the turbidity of two tributaries and
concluded that, as a result of construction runoff, the turbidity
downstream from the construction site was higher than the
turbidity upstream in both tributaries. Michael Mullen Decl.
¶ 23.

   Industry-intervenors contend that the environmental-group
Plaintiffs’ causation evidence is nevertheless insufficient
because they have not definitively established that the pollu-
tion they complain of is composed of the toxic and non-
13166                      NRDC v. USEPA
conventional pollutants that ELGs and NSPSs address. We
disagree. By including the construction industry in plans
issued pursuant to § 304(m), the EPA necessarily identified
the construction industry as a source of toxic and non-
conventional pollutants. See CWA § 304(m)(1)(B) (requiring
the EPA to publish a plan identifying “categories of sources
discharging toxic or nonconventional pollutants for which
guidelines . . . have not previously been published”) (empha-
sis added). In fact, the EPA has explicitly stated that storm
water runoff from construction sites includes toxic and non-
conventional pollutants.7

   American Petroleum Institute v. EPA, 216 F.3d 50 (D.C.
Cir. 2000), does not suggest that any further evidence of cau-
sation is required in this case. In American Petroleum Insti-
tute, the plaintiffs challenged the EPA’s decision not to list
sediment found in discarded unleaded gasoline storage tanks
(UGSTS) as hazardous waste under the Resource Conserva-
tion and Recovery Act (RCRA). Id. at 63. The plaintiffs’
standing was challenged on the ground that they failed “to
link the harms of which their members complain with the reg-
  7
    For example, the EPA stated in 1999 that storm water runoff “may
contain or mobilize high levels of contaminants,” including “toxic pollu-
tants [and] toxins,” and that the highest concentrations of such contami-
nants occurs “during the first major storm after an extended dry period.”
64 Fed. Reg. 68,722, 68,724 (Dec. 8, 1999). The EPA went on to state
“[i]ndividually and combined, these pollutants impair water quality,
threatening designated beneficial uses and causing habitat alteration or
destruction.” Id. The EPA further concluded that intensive construction
activity may severely impact watersheds “because of high pollutant loads,
primarily sediments.” Id. at 68,728. Though the EPA later suggested that
discharge from the construction industry was “predominately” or “almost
entirely” composed of conventional pollutants and that the EPA lacked
data to indicate that toxic and non-conventional pollutants are found in
construction site runoff nationwide, these statements do not squarely reject
the EPA’s earlier statements and still allow that the discharge at issue is
composed of at least some toxic or non-conventional pollutants or toxins.
See 69 Fed. Reg. at 53,718 (Sept. 2, 2004); 71 Fed. Reg. at 76,664 (Dec.
21, 2006); 69 Fed. Reg. 22,472, 22,480 (April 26, 2004).
                        NRDC v. USEPA                      13167
ulatory actions that they wish EPA to take.” Id. The D.C. Cir-
cuit faulted the plaintiffs for failing to present evidence that
the landfills that their members lived near were “of a class
substantially likely to receive UGSTS-filled shipments” or
that “the effects of UGSTS are evident in the landfill’s
groundwater.” Id. at 64. The court further noted that the affi-
davits the plaintiffs submitted did not trace the pollution of
concern to UGSTS waste. Id. at 65. In contrast to the plain-
tiffs in American Petroleum Institute, who were challenging
the EPA’s failure to classify one particular pollutant as haz-
ardous waste, the Plaintiffs here allege the EPA has violated
a statute “designed to reduce the risk of pollution.” We have
previously noted that the CWA, in contrast to the statute at
issue in American Petroleum Institute, “embodies a range of
prophylactic . . . rules designed to reduce the risk of pollu-
tion.” Ecological Rights Found., 230 F.3d at 1152 n.12. And
we have further stated that “[i]t is not necessary for a plaintiff
challenging violations of rules designed to reduce the risk of
pollution to show the presence of actual pollution in order to
obtain standing.” Id.

   [10] Second, by requiring effluent limitations, which are
developed according to ELGs and NSPSs, as a part of a strat-
egy to eliminate the discharge of pollutants and restore and
maintain the integrity of the Nation’s waters, 33 U.S.C.
§ 1251(a), Congress has expressed its view that developing
ELGs and NSPSs reduces the risk of the pollution causing the
members’ injury. Where Congress has expressed the need for
specific regulations relating to the environment, that expres-
sion supports an inference that there is a causal connection
between the lack of those regulations and adverse environ-
mental effects. See Nat’l Wildlife Fed’n, 839 F.2d at 708; see
also Alaska Ctr. for the Env’t v. Browner, 20 F.3d 981, 984-
85 (9th Cir. 1994) (noting that plaintiffs could meet the
redressability requirement because Congress had already
determined the relief they sought was the appropriate means
of achieving desired water quality where other methods had
failed); cf. Int’l Ladies Garment Workers’ Union v. Donovan,
13168                       NRDC v. USEPA
722 F.2d 795, 811-12 (D.C. Cir. 1983) (“[A]s Congress
passed the Act partly to provide redress to employers from
unfair competition, the suggestion that effective enforcement
of the Act will not have this effect directly contravenes the
congressional judgment underlying the Act.”).

   [11] Together, the members’ declarations establishing that
storm water discharge from the construction industry is pol-
luting the waterways they use, the EPA’s findings that such
discharge may consist of toxic and non-conventional pollu-
tants, and Congress’ determination that ELGs and NSPSs
reduce the risk of such pollution, are sufficient to establish
“traceability” and “redressability.” Based on the foregoing,
we conclude that the environmental-group Plaintiffs have
standing.

        b.    State-intervenors

   Only one of the Plaintiffs must have standing to permit our
review. Thus, we consider the state-intervenors’ standing, a
matter that industry-intervenors challenge, only very briefly.
See Massachusetts v. EPA, 127 S. Ct. at 1453 (“Only one of
the petitioners needs to have standing to permit us to consider
the petition for review.”). As with the environmental-group
Plaintiffs, the industry-intervenors contend that the state-
intervenors do not claim an injury that is traceable to the
EPA’s decision not to promulgate ELGs and NSPSs or that
would be redressed by the promulgation of EGLs or NSPSs.

   [12] State-intervenors claim an injury to their proprietary
interest in protecting their waterways.8 See City of Sausalito
  8
   The industry-intervenors incorrectly assert that the state-intervenors are
barred from litigating as parens patrie to enforce a federal statute against
the federal government. In Massachusetts v. EPA, the Supreme Court rec-
ognized that Massachusetts (among other states) was entitled to challenge
the EPA’s rejection of its rulemaking petition regarding motor-vehicle
emissions under the CWA. 127 S. Ct. at 1454-55. The Court noted that
                            NRDC v. USEPA                              13169
v. O’Neill, 386 F.3d 1186, 1198 (9th Cir. 2004) (“A munici-
pality . . . has a proprietary interest in protecting its natural
resources from harm.”). Specifically, they claim that they are
injured by the increased pollution in their waterways from
upstream, out-of-state construction sites due to the absence of
national standards to govern storm water runoff from con-
struction sites. This injury is sufficient to constitute an injury
in fact. See id. (concluding that the City of Sausalito met its
burden to establish an “injury in fact” based on its proprietary
interests).

   [13] The state-intervenors have also submitted declarations
to establish that the pollution they complain of is connected
to a lack of national standards. Patricia Primi, an Environmen-
tal Scientist in the Environmental Protection Bureau of the
New York State Office of the Attorney General, submitted a
declaration attesting that storm water runoff from construction
sites in Vermont, New Hampshire, and Massachusetts is con-
tributing pollutants to the Long Island Sound, and that storm
water runoff from Vermont is contributing pollutants to the
Lake Champlain Basin. Patricia Primi Decl. ¶¶ 18-19, 23-24.
Angus Eaton, the Chief of the General Permits Section in the
Division of Water for the New York State Department of
Environmental Conservation, submitted a declaration support-
ing that the upstream states to which Primi referred have dif-
ferent discharge standards enabling a discharge downstream

given Congress’ recognition of a procedural right to challenge the rejec-
tion of rulemaking petitions and “Massachusetts’ stake in protecting its
quasi-sovereign interest to protect its territory, the Commonwealth is enti-
tled to special solicitude in our standing analysis.” Id. In reaching this con-
clusion, the court relied on Georgia v. Tennessee Copper Company, in
which Georgia’s quasi-sovereign interest in “all the earth and air within
its domain” supported federal jurisdiction over its efforts to protect its sov-
ereign territory from air pollution originating outside its borders. 206 U.S.
230, 236-37 (1907). Likewise, here, the state-intervenors have an interest
in protecting in-state waterways from pollution originating outside their
borders.
13170                 NRDC v. USEPA
of excessive amounts of “pollutants found in stormwater run-
off” from construction sites. Angus K. Eaton Decl. ¶ 16. And,
as stated above, we take into account Congress’ view that the
promulgation of ELGs and NSPSs will reduce the likelihood
of the pollution of which the state-intervenors complain. See
supra Section B.2.a. We therefore conclude that the state-
intervenors also have standing.

  C.     The EPA’s Duty to Promulgate ELGs and NSPSs

    1.    Standard of Review

   We review a district court’s grant of summary judgment de
novo. Buono, 371 F.3d at 545. And, as stated above, we
review the district court’s interpretation of the CWA de novo.
League of Wilderness Defenders/Blue Mountains Biodiversity
Project, 309 F.3d at 1183. Summary judgment is appropriate
“if the pleadings, the discovery and disclosure materials on
file, and any affidavits show that there is no genuine issue as
to any material fact and that the movant is entitled to judg-
ment as a matter of law.” Fed. R. Civ. P. 56(c).

    2.    Analysis

   We must decide whether the EPA had discretion to deter-
mine whether to promulgate ELGs and NSPSs for storm
water runoff from the construction industry once it listed the
construction industry as a point source category in a plan pub-
lished pursuant to § 304(m). We hold that once the EPA listed
the construction industry as a point-source category, it was
required to promulgate ELGs and NSPSs. We therefore affirm
the district court’s grant of summary judgment and the perma-
nent injunction.

  When reviewing the EPA’s construction of a statute that it
administers, we follow the two-step approach set forth in
Chevron U.S.A. v. Natural Res. Def. Council, 467 U.S. 837,
842-44 (1984). At step one, if Congress has “unambiguously
                       NRDC v. USEPA                       13171
expressed its intent on the issue before the court . . . ‘the
court, as well as the agency, must give effect to the unam-
biguously expressed intent of Congress.’ ” Natural Res. Def.
Council v. EPA, 526 F.3d 591, 602 (9th Cir. 2008) (quoting
Chevron, 467 U.S. at 842-43 & n.9). But if the statute is “si-
lent or ambiguous” with respect to the issue before the court,
we will proceed to step two and decide if the agency’s inter-
pretation “ ‘is based on a permissible construction of the stat-
ute.’ ” Id. (quoting Chevron, 467 U.S. at 843). We defer to the
agency’s interpretation as long as it is “based on a permissible
construction.” Chevron, 467 U.S. at 843.

   [14] We conclude that the language of the CWA, when
viewed in its entirety, is clear that the EPA must promulgate
ELGs and NSPSs for the point-source categories it lists in any
plan it publishes under § 304(m). Our analysis begins with
§ 304(m)(1), which requires the EPA, every two years after
February 4, 1987, to “publish in the Federal Register a plan
that shall”

    (A) establish a schedule for the annual review and
    revision of promulgated effluent guidelines . . . ; (B)
    identify categories of sources discharging toxic or
    nonconventional pollutants for which guidelines
    under subsection (b)(2) . . . and section 1316 . . .
    have not previously been published; and (C) estab-
    lish a schedule for promulgation of effluent guide-
    lines for categories identified in subparagraph (B),
    under which promulgation of such guidelines shall
    be no later than . . . 3 years after the publication of
    the plan for categories identified in later published
    plans [i.e. plans not published within 12 months after
    February 4, 1987].

By requiring the EPA to “establish a schedule” under which
the guidelines—the ELGs and NSPSs— are promulgated “no
later than . . . 3 years after the publication of the plan,” Con-
gress’ intent to require the EPA to promulgate guidelines is
13172                       NRDC v. USEPA
clear.9 Indeed, Congress used unequivocal language, stating,
in relevant part: “[the] promulgation of such guidelines shall
be no later than . . . 3 years after the publication of the plan.”
CWA § 304(m) (emphasis added.); see Alabama v. Bozeman,
533 U.S. 146, 153 (2001) (“The word ‘shall’ is ordinarily the
language of command.”) (internal quotation marks and cita-
tion omitted).

   [15] Other provisions in the CWA likewise support that
Congress intended the promulgation of ELGs and NSPSs to
be mandatory once a point-source category was listed in a
plan under § 304(m). See Nat’l Ass’n of Home Builders v.
Defenders of Wildlife, 127 S. Ct. 2518, 2534 (2007) (stating
that the court should not examine statutory provisions in iso-
lation but “with a view to their place in the overall statutory
scheme”) (internal quotation marks and citations omitted).
Section 304(b), which is referenced by § 304(m)(1), states:
“For the purpose of adopting or revising effluent limitations
. . . the Administrator shall . . . publish within one year of
October 18, 1972, regulations, providing guidelines for efflu-
ent limitations.” (Emphasis added). Thus, Congress has con-
  9
   Defendants contend that our analysis of whether the EPA has a non-
discretionary duty to promulgate NSPSs is controlled by § 306, the provi-
sion specifically addressing NSPSs. We disagree. First, because
§ 304(m)(1) expressly references § 306 and applies to both ELGs and
NSPSs, our interpretation of that provision and the duty it creates applies
equally to ELGs and NSPSs identified in a plan under § 304(m)(1).
   Second, the district court, based on information provided by the EPA,
found that “since [§ 304(m)] was enacted, the EPA has promulgated
NSPSs for categories included in [§ 304(m)] plans, but has added no new
categories to [the list of categories in § 306]. Hence [§ 304(m)] seems cur-
rently to be the only vehicle by which the EPA identifies new source cate-
gories for the purpose of developing NSPSs.” The Defendants have not
disputed this finding. We therefore conclude that because § 304(m)—in its
text and in the EPA’s application—grants the EPA the authority to pro-
mulgate both ELGs and NSPSs, our analysis here applies equally to both.
In light of the above, we need not address industry-intervenors’ suggestion
that the Plaintiffs failed to plead a claim for breach of a non-discretionary
duty under § 306.
                       NRDC v. USEPA                      13173
sistently used mandatory language with respect to the
promulgation of ELGs.

   [16] Section 402(a)(1) also supports our interpretation. That
section governs the NPDES and states the EPA may issue
NPDES permits if the discharge will meet: (A) “all applicable
requirements under [various other sections] of this title,”
including the section governing effluent limitations, which are
designed according to ELGs and NSPSs; or (B) if “prior to
the taking of necessary implementing actions relating to all
such requirements, such conditions as the Administrator
determines necessary to carry out the provisions of this chap-
ter.” CWA § 402(a)(1). Subsection (B) is explicit that it
applies only “prior to the taking of necessary implementing
actions” relating to the requirements in subsection (A).
(Emphasis added). Thus, § 402(a)(1)(B) sets forth a system
for assessing NPDES permits only until the EPA promulgates
the requirements referenced in § 402(a)(1)(A) and does not
contemplate that the EPA might never promulgate the require-
ments referenced in § 402(a)(1)(A). Rather, § 402(a)(1) sup-
ports that Congress assumed that “requirements,” including
effluent limitations, which are guided by ELGs and NSPSs,
would be in place after an interim period.

   While we conclude that the CWA is unambiguous that the
EPA must promulgate ELGs and NSPSs for point-source cat-
egories listed in a plan pursuant to § 304(m), were we to find
the statute ambiguous and consider whether the EPA’s inter-
pretation was based on a “permissible construction,” we
would reach the same conclusion.

    The addition of § 304(m) to the CWA stemmed from Con-
gress’ frustration with “the slow pace in which these regula-
tions [were] promulgated.” S. Rep. No. 99-50, at 3 (1985)
(“Although the EPA continues to move forward with develop-
ing guidelines for the installation of cleanup technology for
. . . dischargers, the slow pace in which these regulations are
promulgated continues to be frustrating. Of the 29 industrial
13174                  NRDC v. USEPA
categories established in 1977 for which guidelines were
required to be promulgated 5 still remain to be completed.”).
Congress’s desire to speed up the promulgation of ELGs and
NSPSs would be completely frustrated if § 304 were viewed
merely as a planning mechanism and did not require the
actual promulgation of ELGs and NSPSs. The Senate Report
quoted confirms that Congress did not view § 304 as a plan-
ning mechanism. It states that “[g]uidelines are required for
any category of sources discharging significant amounts of
toxic pollutants. In this use, ‘significant amounts’ does not
require the [EPA] to make any determination of environmen-
tal harm; any non-trivial discharges from sources in a cate-
gory must lead to effluent guidelines.” Id. at 24-25 (emphasis
added).

   Our recent opinion in OCEF does not contradict our inter-
pretation. In OCEF, we held that the EPA’s decisions on
“whether to revise the effluent guidelines and whether to
incorporate technology-based criteria in its periodic review of
the guidelines” were discretionary duties. 527 F.3d at 845.
The duty that the OCEF court found to be discretionary was
entirely distinct from the duty at issue in this case. This case
addresses whether there is a mandatory duty to promulgate
ELGs and NSPSs once a point-source category has been iden-
tified in a plan under § 304(m). In contrast, the OCEF court
considered the EPA’s duty to consider technology-based
criteria when it was performing its mandatory duty to review
effluent limitations and ELGs. Id. at 849. Though the OCEF
court found the statute to be ambiguous on that point and did
not conclude that the duty to consider technology-based
criteria was mandatory, the court acknowledged that “when
Congress specifies an obligation and uses the word ‘shall,’
this denomination usually connotes a mandatory command.”
Id. at 847 (citing Alabama v. Bozeman, 533 U.S. at 153). And
later, in discussing the EPA’s duties in connection with the
identification of new polluting sources, the OCEF court
acknowledged that if a source has any non-trivial discharge of
toxic pollutants, the EPA does not make a determination of
                           NRDC v. USEPA                            13175
environmental harm but “must” promulgate effluent guide-
lines. Id. at 852 (citation omitted) (emphasis added).

   Despite our conclusion that the EPA had a non-
discretionary duty to promulgate ELGs and NSPSs in this
case, we also must consider whether the EPA properly
avoided this duty when it removed the construction industry
from its plans published pursuant to § 304(m). Nothing in the
CWA expressly grants the EPA the authority to remove a
point-source category from a § 304(m) plan. Cf. 42 U.S.C.
§ 7412(c)(9) (Clean Air Act provision expressly granting the
EPA the authority to delist source categories). Moreover, we
do not find the EPA’s view, that it is allowed under the statute
to unilaterally delist a point-source category already identified
in a § 304(m) plan with no process, to be a permissible con-
struction of the statute. See Chevron, 467 U.S. at 843.10

   First, § 304(m)(1)(c) is clear that once a category is identi-
fied under subsection B, the promulgation of guidelines “shall
be no later than . . . 3 years after the publication of the plan.”
This timeline effectuates Congress’ stated desire to force the
EPA to more rapidly promulgate ELGs and NSPSs. If the
EPA had the authority to delist point-source categories at its
whim, however, this deadline would be rendered meaningless
as the EPA could delist any point-source category to avoid the
deadline set forth in § 304(m)(1)(c).

   [17] Second, § 304(m)(2) provides that “[t]he Administra-
tor shall provide for public review and comment on the plan
  10
     We need not reach the question of whether the EPA could avoid pro-
mulgating ELGs and NSPSs for a point-source category that had, at one
time, been included in a § 304(m) plan if the EPA formally amended the
§ 304(m) plan that triggered the duty to promulgate or undertook some
other formal process to delist the point-source category. Here, the EPA has
not established that it engaged in any such process but has submitted its
statements in its 2004 and 2006 § 304(m) plans that it was “not identify-
ing” the construction industry, which had previously been identified in
earlier plans, as a point-source category.
13176                  NRDC v. USEPA
prior to final publication.” Thus, Congress determined that by
the time a point-source category is listed in a § 304(m) plan,
the EPA must have already engaged in a review process to
consider whether the category should be listed. It follows log-
ically that the three-year delay provided for in § 304(m)(1)(c)
is not to decide whether to list a point-source category, but to
allow the EPA to consider what the substance of the ELGs
and NSPSs should be.

                       CONCLUSION

  For these reasons, we AFFIRM the district court.
