(Slip Opinion)              OCTOBER TERM, 2012                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

   DECKER, OREGON STATE FORESTER, ET AL. v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                  THE NINTH CIRCUIT

   No. 11–338.      Argued December 3, 2012—Decided March 20, 2013*
The Clean Water Act (Act) requires that National Pollutant Discharge
  Elimination System (NPDES) permits be secured before pollutants
  are discharged from any point source into the navigable waters of the
  United States. See 33 U. S. C. §§1311(a), 1362(12). One of the Envi-
  ronmental Protection Agency’s (EPA) implementing regulations, the
  Silvicultural Rule, specifies which types of logging-related discharges
  are point sources. 40 CFR §122.27(b)(1). These discharges require
  NPDES permits unless some other federal statutory provision ex-
  empts them from coverage. One such statutory provision exempts
  “discharges composed entirely of stormwater,” 33 U. S. C.
  §1342(p)(1), unless the discharge is “associated with industrial activ-
  ity,” §1342(p)(2)(B). Under the EPA’s Industrial Stormwater Rule,
  the term “associated with industrial activity” covers only discharges
  “from any conveyance that is used for collecting and conveying storm
  water and that is directly related to manufacturing, processing or
  raw materials storage areas at an industrial plant.” 40 CFR
  §122.26(b)(14). Shortly before oral argument in the instant cases, the
  EPA issued a final version of an amendment to the Industrial
  Stormwater Rule, clarifying that the NPDES permit requirement ap-
  plies only to logging operations involving rock crushing, gravel wash-
  ing, log sorting, and log storage facilities, which are all listed in the
  Silvicultural Rule.
     Petitioner Georgia-Pacific West has a contract with Oregon to har-
——————
  * Together with No. 11–347, Georgia-Pacific West, Inc., et al. v.
Northwest Environmental Defense Center, also on certiorari to the same
court.
2      DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                         CENTER

                         Syllabus


    vest timber from a state forest. When it rains, water runs off two
    logging roads used by petitioner into ditches, culverts, and channels
    that discharge the water into nearby rivers and streams. The dis-
    charges often contain large amounts of sediment, which evidence
    shows may be harmful to fish and other aquatic organisms. Re-
    spondent Northwest Environmental Defense Center (NEDC) filed
    suit against petitioner and state and local governments and officials,
    including petitioner Decker, invoking the Act’s citizen-suit provision,
    33 U. S. C. §1365, and alleging that the defendants had not obtained
    NPDES permits before discharging stormwater runoff into two Ore-
    gon rivers. The District Court dismissed the action for failure to
    state a claim, concluding that NPDES permits were not required be-
    cause the ditches, culverts, and channels were not point sources of
    pollution under the Act and the Silvicultural Rule. The Ninth Circuit
    reversed. It held that the conveyances were point sources under the
    Silvicultural Rule. It also concluded that the discharges were “asso-
    ciated with industrial activity” under the Industrial Stormwater
    Rule, despite the EPA’s contrary conclusion that the regulation ex-
    cludes the type of stormwater discharges from logging roads at issue.
    Thus, the court held, the discharges were not exempt from the
    NPDES permitting scheme.
Held:
    1. A provision of the Act governing challenges to agency actions,
 §1369(b), is not a jurisdictional bar to this suit. That provision is the
 exclusive vehicle for suits seeking to invalidate certain agency deci-
 sions, such as the establishment of effluent standards and the issu-
 ance of permits. It does not bar a district court from entertaining a
 citizen suit under §1365 when the suit is against an alleged violator
 and seeks to enforce an obligation imposed by the Act or its regula-
 tions. The present action falls within the scope of §1365. Pp. 8–9.
    2. The EPA’s recent amendment to the Industrial Stormwater Rule
 does not make the cases moot. A live controversy continues to exist
 regarding whether petitioners may be held liable for unlawful dis-
 charges under the earlier version of the Industrial Stormwater Rule.
 That version governed petitioners’ past discharges, which might be
 the basis for the imposition of penalties even if, in the future, those
 types of discharges will not require a permit. These cases thus re-
 main live and justiciable. See Gwaltney of Smithfield, Ltd. v. Chesa-
 peake Bay Foundation, Inc., 484 U. S. 49, 64–65. The fact that the
 District Court might rule that NEDC’s arguments lack merit, or that
 relief is not warranted on the facts of these cases, does not make the
 cases moot. Pp. 9–11.
    3. The preamendment version of the Industrial Stormwater Rule,
 as permissibly construed by the EPA, exempts discharges of chan-
                     Cite as: 568 U. S. ____ (2013)                     3

                                Syllabus

  neled stormwater runoff from logging roads from the NPDES permit-
  ting scheme. The regulation is a reasonable interpretation of the
  statutory term “associated with industrial activity,” §1342(p)(2)(B),
  and the agency has construed the regulation to exempt the discharges
  at issue here. When an agency interprets its own regulation, the
  Court, as a general rule, defers to it “unless that interpretation is
  ‘plainly erroneous or inconsistent with the regulation.’ ” Chase Bank
  USA, N. A. v. McCoy, 562 U. S. ___, ___ (quoting Auer v. Robbins, 519
  U. S. 452, 461). Here, it was reasonable for the EPA to conclude that
  the conveyances at issue are “directly related” only to the harvesting
  of raw materials, rather than to “manufacturing, processing, or raw
  materials storage areas at an industrial plant.”              40 CFR
  §122.26(b)(14). The regulatory scheme, taken as a whole, leaves open
  the rational interpretation that the regulation extends only to tradi-
  tional industrial buildings such as factories and associated sites and
  other relatively fixed facilities.
     Another reason to accord Auer deference to the EPA’s interpreta-
  tion is that there is no indication that the agency’s current view is a
  change from prior practice or is a post hoc justification adopted in re-
  sponse to litigation. See Christopher v. SmithKline Beecham Corp.,
  567 U. S. ___, ___. Rather, the EPA has been consistent in its view
  that the types of discharges at issue do not require NPDES permits.
  Its decision also exists against a background of state regulation with
  respect to stormwater runoff from logging roads. In exercising the
  broad discretion the Act gives the EPA in the realm of stormwater
  runoff, the agency could reasonably have concluded that further fed-
  eral regulation would be duplicative or counterproductive in light of
  Oregon’s extensive rules on the subject. Pp. 11–15.
640 F. 3d 1063, reversed and remanded.

   KENNEDY, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and THOMAS, GINSBURG, ALITO, SOTOMAYOR, and KAGAN, JJ.,
joined, and in which SCALIA, J., joined as to Parts I and II. ROBERTS,
C. J., filed a concurring opinion, in which ALITO, J., joined. SCALIA, J.,
filed an opinion concurring in part and dissenting in part. BREYER, J.,
took no part in the consideration or decision of the cases.
                       Cite as: 568 U. S. ____ (2013)                              1

                            Opinion of the Court

    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash-
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                          Nos. 11–338 and 11–347
                                  _________________


 DOUG DECKER, IN HIS OFFICIAL CAPACITY AS OREGON
       STATE FORESTER, ET AL., PETITIONERS
11–338                 v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER

GEORGIA-PACIFIC WEST, INC., ET AL., PETITIONERS
11–347               v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE NINTH CIRCUIT
                               [March 20, 2013]

  JUSTICE KENNEDY delivered the opinion of the Court.
  These cases present the question whether the Clean
Water Act (Act) and its implementing regulations require
permits before channeled stormwater runoff from logging
roads can be discharged into the navigable waters of the
United States. Under the statute and its implementing
regulations, a permit is required if the discharges are
deemed to be “associated with industrial activity.” 33
U. S. C. §1342(p)(2)(B). The Environmental Protection
Agency (EPA), with the responsibility to enforce the Act,
has issued a regulation defining the term “associated with
industrial activity” to cover only discharges “from any
conveyance that is used for collecting and conveying storm
water and that is directly related to manufacturing, pro-
cessing or raw materials storage areas at an industrial
2   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                       CENTER

                  Opinion of the Court 


plant.” 40 CFR 122.26(b)(14) (2006). The EPA interprets
its regulation to exclude the type of stormwater discharges
from logging roads at issue here. See Brief for United
States as Amicus Curiae 24–27. For reasons now to be
explained, the Court concludes the EPA’s determination is
a reasonable interpretation of its own regulation; and, in
consequence, deference is accorded to the interpretation
under Auer v. Robbins, 519 U. S. 452, 461 (1997).
                             I

                            A

   Congress passed the Clean Water Act in 1972 to “restore
and maintain the chemical, physical, and biological integ-
rity of the Nation’s waters.” 86 Stat. 816, 33 U. S. C.
§1251(a). A central provision of the Act is its require-
ment that individuals, corporations, and governments se-
cure National Pollutant Discharge Elimination System
(NPDES) permits before discharging pollution from any
point source into the navigable waters of the United
States. See §§1311(a), 1362(12); EPA v. California ex rel.
State Water Resources Control Bd., 426 U. S. 200, 205
(1976). The Act defines “point source” as
    “any discernible, confined and discrete conveyance, in-
    cluding but not limited to any pipe, ditch, channel,
    tunnel, conduit, well, discrete fissure, container, roll-
    ing stock, concentrated animal feeding operation, or
    vessel or other floating craft, from which pollutants
    are or may be discharged. This term does not include
    agricultural stormwater discharges and return flows
    from irrigated agriculture.” §1362(14).
  When the Act took effect, the EPA found it difficult to
process permit applications from countless owners and
operators of point sources throughout the country. The
agency issued regulations exempting certain types of
point-source discharges from the NPDES permitting
                 Cite as: 568 U. S. ____ (2013)            3

                     Opinion of the Court

scheme, but in 1977 those directives were found invalid.
The Court of Appeals for the District of Columbia Circuit
ruled that the statute did not give the EPA “authority to
exempt categories of point sources from the permit re-
quirements” of the Act. Natural Resources Defense Coun-
cil, Inc. v. Costle, 568 F. 2d 1369, 1377. In response the
EPA issued new regulations to define with more precision
which categories of discharges qualified as point sources in
the first place. Among these regulations was the so-called
Silvicultural Rule. This rule is at issue here. It provides:
     “Silvicultural point source means any discernible,
    confined and discrete conveyance related to rock
    crushing, gravel washing, log sorting, or log storage
    facilities which are operated in connection with silvi-
    cultural activities and from which pollutants are dis-
    charged into waters of the United States. The term
    does not include non-point source silvicultural activi-
    ties such as nursery operations, site preparation,
    reforestation and subsequent cultural treatment,
    thinning, prescribed burning, pest and fire control,
    harvesting operations, surface drainage, or road con-
    struction and maintenance from which there is natu-
    ral runoff.” 40 CFR §122.27(b)(1).
  Under the quoted rule, any discharge from a logging-
related source that qualifies as a point source requires an
NPDES permit unless some other federal statutory provi-
sion exempts it from that coverage. In one such provision,
33 U. S. C. §1342(p), Congress has exempted certain dis-
charges of stormwater runoff. The statutory exemptions
were considered necessary because, from the outset, the
EPA had encountered recurring difficulties in determining
how best to manage discharges of this kind. See, e.g.,
Natural Resources Defense Council, Inc. v. EPA, 966 F. 2d
1292, 1295–1296 (CA9 1992). In 1987, Congress responded
to these problems and adopted various stormwater-related
4    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
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                   Opinion of the Court 


amendments to the Act. §405, 101 Stat. 69, 33 U. S. C.
§1342(p).
   The 1987 amendments exempt from the NPDES permit-
ting scheme most “discharges composed entirely of storm-
water.” §1342(p)(1). The general exemption, however, does
not extend to all stormwater discharges. As relevant here,
Congress directed the EPA to continue to require per-
mits for stormwater discharges “associated with indus-
trial activity.” §1342(p)(2)(B). The statute does not define
that term, but the EPA adopted a regulation (hereinafter
Industrial Stormwater Rule) in which it defined it as
    “the discharge from any conveyance that is used for
    collecting and conveying storm water and that is
    directly related to manufacturing, processing or raw
    materials storage areas at an industrial plant. The
    term does not include discharges from facilities or ac-
    tivities excluded from the NPDES program under this
    part 122. For the categories of industries identified
    in this section, the term includes, but is not limited
    to, storm water discharges from . . . immediate access
    roads and rail lines used or traveled by carriers of raw
    materials, manufactured products, waste material, or
    by-products used or created by the facility . . . .” 40
    CFR §122.26(b)(14) (2006).
   The Industrial Stormwater Rule also specified that, with
one exception not relevant here, “[f ]acilities classified
as Standard Industrial Classificatio[n] 24” are “considered
to be engaging in ‘industrial activity’ for purposes of para-
graph (b)(14).” Ibid. The Standard Industrial Classifica-
tions are a system used by federal agencies to categorize
firms engaged in different types of business activity. See
Dept. of Labor, Standard Industrial Classifications Manual,
online at http://www.osha.gov/pls/imis/sic_manual.html (as
visited Mar. 14, 2013, and available in Clerk of Court’s
case file). Standard Industrial Classification 24 identifies
                 Cite as: 568 U. S. ____ (2013)             5

                     Opinion of the Court

industries involved in the field of “Lumber and Wood
Products.” 2 App. 64. This includes the “Logging” indus-
try, defined as “[e]stablishments primarily engaged in
cutting timber and in producing . . . primary forest or
wood raw materials.” Ibid.
   On November 30, 2012—three days before the instant
cases were argued in this Court—the EPA issued its final
version of an amendment to the Industrial Stormwater
Rule. The amendment was the agency’s response to the
Court of Appeals’ ruling now under review. The amended
version seeks to clarify the types of facilities within
Standard Industrial Classification 24 that are deemed to
be engaged in industrial activity for purposes of the rule.
The amended Industrial Stormwater Rule does not cover
all facilities within Standard Industrial Classification 24.
It limits covered stormwater discharges to
    “[f ]acilities classified within Standard Industrial Clas-
    sification 24, Industry Group 241 that are rock crushing,
    gravel washing, log sorting, or log storage facilities
    operated in connection with silvicultural activities
    . . . and Industry Groups 242 through 249.” 77 Fed.
    Reg. 72974, pt. 122, subpt. B (2012).
It should be noted, by way of explanation, that an Indus-
try Group is a subcategory of businesses within a Stand-
ard Industrial Classification. Industry Group 241 is
“Logging,” while Industry Groups 242 through 245 are,
respectively, “Sawmills and Planing Mills,” “Millwork,
Veneer, Plywood, and Structural Wood,” “Wood Contain-
ers,” and “Wood Buildings and Mobile Homes.” Industry
Group 249 is “Miscellaneous Wood Products.” Industry
Groups 246 through 248 are blank categories. Standard
Industrial Classifications Manual, supra, Major Group 24.
   It is fair to say the purpose of the amended regulation is
to bring within the NPDES permit process only those
logging operations that involve the four types of activity
6    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                        CENTER

                   Opinion of the Court 


(rock crushing, gravel washing, log sorting, and log stor-
age facilities) that are defined as point sources by the
explicit terms of the Silvicultural Rule.
  Up to this stage in the litigation, of course, the cases
have been concerned with the Industrial Stormwater Rule
before the amendment adopted on November 30, 2012.
The amended regulation will determine whether from this
point forward NPDES permits will be required for the
stormwater discharges at issue. The parties disagree
about the significance of the amended rule for purposes of
these cases. Before reaching this and other preliminary
points, however, it is appropriate to set forth the facts and
history of the cases leading to the proceedings in this
Court.
                             B
  At issue are discharges of channeled stormwater runoff
from two logging roads in Oregon’s Tillamook State For-
est, lying in the Pacific Coast Range about 40 miles west
of Portland. Petitioner Georgia-Pacific West, along with
other logging and paper-products companies, has a con-
tract with the State of Oregon to harvest timber from the
forest. It uses the roads for that purpose. When it rains
(which it does often in the mountains of northwest Oregon,
averaging in some areas more than 100 inches per year),
water runs off the graded roads into a system of ditches,
culverts, and channels that discharge the water into
nearby rivers and streams. The discharges often contain
large amounts of sediment, in the form of dirt and crushed
gravel from the roads. There is evidence that this runoff
can harm fish and other aquatic organisms.
  In September 2006, respondent Northwest Environmen-
tal Defense Center (NEDC) filed suit in the United States
District Court for the District of Oregon. It invoked the
Clean Water Act’s citizen-suit provision, 33 U. S. C. §1365,
and named as defendants certain firms involved in log-
                 Cite as: 568 U. S. ____ (2013)           7

                     Opinion of the Court

ging and paper-products operations (including petitioner
Georgia-Pacific West), as well as state and local govern-
ments and officials (including the State Forester of Oregon,
who is now petitioner Doug Decker). The suit alleged that
the defendants caused discharges of channeled stormwater
runoff into two waterways—the South Fork Trask River
and the Little South Fork Kilchis River. The defendants
had not obtained NPDES permits, and so, the suit alleged,
they had violated the Act.
  The District Court dismissed the action for failure to
state a claim. It concluded that NPDES permits were not
required because the ditches, culverts, and channels were
not point sources of pollution under the Act and the Silvi-
cultural Rule. The Court of Appeals for the Ninth Cir-
cuit reversed. Northwest Environmental Defense Center v.
Brown, 640 F. 3d 1063 (2011). It relied upon three princi-
pal propositions. First, it held that the District Court had
subject-matter jurisdiction under §1365 notwithstanding
a different provision of the Act, 33 U. S. C. §1369(b)(1),
limiting judicial review of EPA regulations. Second, the
Court of Appeals held that while the EPA’s Silvicultural
Rule is ambiguous on the question whether the convey-
ances at issue are point sources, those conveyances must
be deemed point sources under the rule in order to give
effect to the Act’s expansive definition of the term. Third,
the Court of Appeals held that because the Industrial
Stormwater Rule makes cross-reference to Standard In-
dustrial Classification 24, the discharges at issue are
“associated with industrial activity” within the meaning
of the regulation, despite the EPA’s conclusion to the con-
trary. The regulation was held to be unambiguous on this
point. The Court of Appeals thus ruled that the dis-
charges were from point sources and not exempt from the
NPDES permitting scheme by the Industrial Stormwater
Rule. It followed that petitioners had been in violation of
the Act.
8     DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE

                         CENTER

                    Opinion of the Court 


    This Court granted certiorari. 567 U. S. ___ (2012).
                             II
  Before proceeding to the merits, it is necessary to con-
sider two jurisdictional questions.
                              A
   Respondent NEDC invoked the jurisdiction of the Dis-
trict Court under 33 U. S. C. §1365(a), which “authorize[s]
private enforcement of the provisions of [the Clean Water
Act]” and its implementing regulations. Department of
Energy v. Ohio, 503 U. S. 607, 613, n. 5 (1992). Petition-
ers, however, maintain that this suit is barred by a sepa-
rate provision of the Act, §1369(b). That statute provides
for “judicial review in the United States courts of appeals
of various particular actions by the [EPA] Administrator,
including establishment of effluent standards and issu-
ance of permits for discharge of pollutants.” Middlesex
County Sewerage Authority v. National Sea Clammers
Assn., 453 U. S. 1, 13–14 (1981). Where that review is
available, it is the exclusive means of challenging actions
covered by the statute, §1369(b)(2), and an application for
review must be lodged in the court of appeals within 120
days of the Administrator’s action, §1369(b)(1).
   The Court of Appeals was correct to rule that the exclu-
sive jurisdiction mandate is not applicable in this suit.
Section 1369(b) extends only to certain suits challenging
some agency actions. It does not bar a district court from
entertaining a citizen suit under §1365 when the suit is
against an alleged violator and seeks to enforce an obliga-
tion imposed by the Act or its regulations.
   The present action is within the scope of §1365. It is a
claim to enforce what is at least a permissible reading of
the Silvicultural Rule. The rule is ambiguous: Its charac-
terization of silvicultural harvesting operations “from
which there is natural runoff,” 40 CFR §122.27(b)(1), as a
                 Cite as: 568 U. S. ____ (2013)            9

                     Opinion of the Court

nonpoint source might be read, as petitioners contend, to
apply to the channeled stormwater runoff at issue; or it
might be read, as respondent NEDC urges, to apply only
to runoff not collected in channels or other engineered
improvements. See New Oxford American Dictionary
1167 (3d ed. 2010) (Oxford Dict.) (“natural” means “existing
in or caused by nature; not made or caused by human-
kind”). NEDC’s reading would make the channeled dis-
charges here point-source pollution under the Act. In its
view only this interpretation can be squared with the Act’s
broad definition of “point source.” 33 U. S. C. §1362(14).
On this premise, the instant suit is an effort not to chal-
lenge the Silvicultural Rule but to enforce it under a
proper interpretation. It is a basic tenet that “regulations,
in order to be valid, must be consistent with the statute
under which they are promulgated.” United States v.
Larionoff, 431 U. S. 864, 873 (1977).
   For jurisdictional purposes, it is unnecessary to deter-
mine whether NEDC is correct in arguing that only its
reading of the Silvicultural Rule is permitted under the
Act. It suffices to note that NEDC urges the Court to
adopt a “purposeful but permissible reading of the regula-
tion . . . to bring it into harmony with . . . the statute.”
Environmental Defense v. Duke Energy Corp., 549 U. S.
561, 573 (2007). NEDC does not seek “an implicit declara-
tion that the . . . regulations were invalid as written.”
Ibid. And, as a result, §1369(b) is not a jurisdictional bar
to this suit.
                             B
  “It is a basic principle of Article III that a justiciable
case or controversy must remain extant at all stages of
review, not merely at the time the complaint is filed.”
United States v. Juvenile Male, 564 U. S. ___, ___ (2011)
(per curiam) (slip op., at 4) (internal quotation marks
omitted). This principle requires us to determine whether
10   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                        CENTER
                   Opinion of the Court

the EPA’s recent amendment to the Industrial Stormwater
Rule makes the cases moot. In a supplemental brief filed
after oral argument, petitioner Decker, joined by the
United States as amicus curiae, takes the position that the
recent amendment makes these cases moot in relevant part.
See Supp. Brief for Petitioners in No. 11–338, pp. 4–6;
Supp. Brief for United States as Amicus Curiae 4–8.
   That conclusion is incorrect. “A case becomes moot only
when it is impossible for a court to grant any effectual
relief whatever to the prevailing party.” Knox v. Service
Employees Int’l, 567 U. S. ___, ___ (2012) (slip op., at 7)
(internal quotation marks omitted). Here, despite the
recent amendment, a live controversy continues to exist
regarding whether petitioners may be held liable for un-
lawful discharges under the earlier version of the Indus-
trial Stormwater Rule.
   Respondent NEDC continues to press its claim that
petitioners’ discharges are unlawful under both the
amended regulation and the earlier version. See Supp.
Brief for Respondent 3–13. The instant cases provide no
occasion to interpret the amended regulation. “ ‘[W]e are a
court of review, not of first view.’ ” Arkansas Game and
Fish Comm’n v. United States, ante, at 13 (quoting Cutter
v. Wilkinson, 544 U. S. 709, 718, n. 7 (2005)). The parties,
however, have litigated the suit extensively based on the
earlier version of the Industrial Stormwater Rule; and
that version governed petitioners’ past discharges, which
might be the basis for the imposition of penalties even if,
in the future, those types of discharges will not require a
permit.
   If the Court of Appeals is correct that petitioners were
obligated to secure NPDES permits before discharging
channeled stormwater runoff, the District Court might
order some remedy for their past violations. The Act
contemplates civil penalties of up to $25,000 per day, 33
U. S. C. §1319(d), as well as attorney’s fees for prevailing
                  Cite as: 568 U. S. ____ (2013)           11

                      Opinion of the Court

parties, §1365(d). NEDC, in addition, requests injunctive
relief for both past and ongoing violations, in part in the
form of an order that petitioners incur certain environmental-
remediation costs to alleviate harms attributable to
their past discharges. Under these circumstances, the
cases remain live and justiciable, for the possibility of
some remedy for a proven past violation is real and not
remote. See Gwaltney of Smithfield, Ltd. v. Chesapeake
Bay Foundation, Inc., 484 U. S. 49, 64–65 (1987). The
District Court, it is true, might rule that NEDC’s argu-
ments lack merit, or that the relief it seeks is not warranted
on the facts of these cases. That possibility, however, does
not make the cases moot. “There may be jurisdiction and
yet an absence of merits.” General Investment Co. v.
New York Central R. Co., 271 U. S. 228, 230 (1926).
                             III
   The substantive question of the necessity for an NPDES
permit under the earlier rule now must be addressed.
Under the Act, petitioners were required to secure NPDES
permits for the discharges of channeled stormwater runoff
only if the discharges were “associated with industrial
activity,” 33 U. S. C. §1342(p)(2)(B), as that statutory term
is defined in the preamendment version of the Industrial
Stormwater Rule, 40 CFR §122.26(b)(14) (2006). Other-
wise, the discharges fall within the Act’s general exemp-
tion of “discharges composed entirely of stormwater” from
the NPDES permitting scheme. 33 U. S. C. §1342(p)(1).
   NEDC first contends that the statutory term “associated
with industrial activity” unambiguously covers discharges
of channeled stormwater runoff from logging roads. See
Chevron U. S. A. Inc. v. Natural Resources Defense Council,
Inc., 467 U. S. 837, 842–843 (1984). That view, however,
overlooks the multiple definitions of the terms “indus-
trial” and “industry.” These words can refer to business
activity in general, yet so too can they be limited to “eco-
12   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
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                   Opinion of the Court 


nomic activity concerned with the processing of raw mate-
rials and manufacture of goods in factories.” Oxford Dict.
887. The latter definition does not necessarily encompass
outdoor timber harvesting. The statute does not foreclose
more specific definition by the agency, since it provides no
further detail as to its intended scope.
   Somewhat more plausible is NEDC’s claim that the
preamendment version of the Industrial Stormwater Rule
unambiguously required a permit for the discharges at
issue. NEDC reasons that under the rule, “[f]or the cate-
gories of industries identified in this section,” NPDES
permits are required for, among other things, “storm
water discharges from . . . immediate access roads . . . used
or traveled by carriers of raw materials.”            40 CFR
§122.26(b)(14) (2006). Yet this raises the question wheth-
er logging is a “categor[y] of industr[y]” identified by the
section. The regulation goes on to identify a list of “cate-
gories of facilities” that “are considered to be engaging in
‘industrial activity’ for purposes” of the Industrial Storm-
water Rule. Ibid. In the earlier version of the regulation,
this list included “[f]acilities classified as Standard Indus-
trial Classificatio[n] 24,” which encompasses “Logging.”
Ibid. See also supra, at 4–5. Hence, NEDC asserts, log-
ging is among the categories of industries for which “storm
water discharges from . . . immediate access roads . . . used
or traveled by carriers of raw materials” required NPDES
permits under the earlier version of the Industrial Storm-
water Rule. §122.26(b)(14). NEDC further notes, in sup-
port of its reading of the regulation, that modern logging is
a large-scale, highly mechanized enterprise, using sophis-
ticated harvesting machines weighing up to 20 tons. See
Brief for Respondent 4–5.
   The EPA takes a different view. It concludes that the
earlier regulation invoked Standard Industrial Classifica-
tion 24 “ ‘to regulate traditional industrial sources such
as sawmills.’ ” Brief for United States as Amicus Curiae
                  Cite as: 568 U. S. ____ (2013)           13

                      Opinion of the Court

24–25. It points to the regulation’s reference to “facilities”
and the classification’s reference to “establishments,”
which suggest industrial sites more fixed and permanent
than outdoor timber-harvesting operations. Ibid. See also
55 Fed. Reg. 47990, 48008 (1990). This reading is re-
inforced by the Industrial Stormwater Rule’s definition
of discharges associated with industrial activity as dis-
charges “from any conveyance that is used for collecting
and conveying storm water and that is directly related to
manufacturing, processing or raw materials storage areas
at an industrial plant.” 40 CFR §122.26(b)(14) (2006).
This language lends support to the EPA’s claim that the
regulation does not cover temporary, outdoor logging
installations. It was reasonable for the agency to conclude
that the conveyances at issue are “directly related” only to
the harvesting of raw materials, rather than to “manufac-
turing,” “processing,” or “raw materials storage areas.”
See Oxford Dict. 1066 (manufacturing is “mak[ing] (some-
thing) on a large scale using machinery”); id., at 1392
(processing is “perform[ing] a series of mechanical or
chemical operations on (something) in order to change or
preserve it”). In addition, even if logging as a general
matter is a type of economic activity within the regula-
tion’s scope, a reasonable interpretation of the regulation
could still require the discharges to be related in a direct
way to operations “at an industrial plant” in order to be
subject to NPDES permitting.
   NEDC resists this conclusion, noting that elsewhere in
the Industrial Stormwater Rule the EPA has required
NPDES permits for stormwater discharges associated
with other types of outdoor economic activity.            See
§122.26(b)(14)(iii) (mining); §122.26(b)(14)(v) (landfills
receiving industrial waste); §122.26(b)(14)(x) (large con-
struction sites). The EPA reasonably could conclude,
however, that these types of activities tend to be more
fixed and permanent than timber-harvesting operations
14   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                        CENTER

                   Opinion of the Court 


are and have a closer connection to traditional industrial
sites. In light of the language of the regulation just dis-
cussed, moreover, the inclusion of these types of economic
activity in the Industrial Stormwater Rule need not be
read to mandate that all stormwater discharges related to
these activities fall within the rule, just as the inclusion of
logging need not be read to extend to all discharges from
logging sites. The regulation’s reach may be limited by
the requirement that the discharges be “directly related to
manufacturing, processing or raw materials storage areas
at an industrial plant.” §122.26(b)(14).
   It is well established that an agency’s interpretation
need not be the only possible reading of a regulation—or
even the best one—to prevail. When an agency interprets
its own regulation, the Court, as a general rule, defers to it
“unless that interpretation is ‘plainly erroneous or incon-
sistent with the regulation.’ ” Chase Bank USA, N. A. v.
McCoy, 562 U. S. ___, ___ (2011) (slip op., at 12) (quoting
Auer, 519 U. S., at 461). The EPA’s interpretation is
a permissible one. Taken together, the regulation’s ref-
erences to “facilities,” “establishments,” “manufacturing,”
“processing,” and an “industrial plant” leave open the
rational interpretation that the regulation extends only to
traditional industrial buildings such as factories and
associated sites, as well as other relatively fixed facilities.
   There is another reason to accord Auer deference to the
EPA’s interpretation: there is no indication that its cur-
rent view is a change from prior practice or a post hoc
justification adopted in response to litigation. See Chris-
topher v. SmithKline Beecham Corp., 567 U. S. ___, ___
(2012) (slip op., at 10). The opposite is the case. The
agency has been consistent in its view that the types of
discharges at issue here do not require NPDES permits.
   The EPA’s decision exists against a background of state
regulation with respect to stormwater runoff from logging
roads. The State of Oregon has made an extensive effort
                  Cite as: 568 U. S. ____ (2013)            15

                      Opinion of the Court

to develop a comprehensive set of best practices to manage
stormwater runoff from logging roads. These practices
include rules mandating filtration of stormwater runoff
before it enters rivers and streams, Ore. Admin. Rule 629–
625–0330(4) (2012); requiring logging companies to con-
struct roads using surfacing that minimizes the sediment
in runoff, Rule 629–625–0700(2); and obligating firms to
cease operations where such efforts fail to prevent vis-
ible increases in water turbidity, Rule 629–625–0700(3).
Oregon has invested substantial time and money in estab-
lishing these practices. In addition, the development,
siting, maintenance, and regulation of roads—and in
particular of state forest roads—are areas in which Ore-
gon has considerable expertise. In exercising the broad
discretion the Clean Water Act gives the EPA in the realm
of stormwater runoff, the agency could reasonably have
concluded that further federal regulation in this area
would be duplicative or counterproductive. Indeed, Con-
gress has given express instructions to the EPA to work
“in consultation with State and local officials” to alleviate
stormwater pollution by developing the precise kind of
best management practices Oregon has established here.
33 U. S. C. §1342(p)(6).
                         *     *    *
  The preamendment version of the Industrial Storm-
water Rule, as permissibly construed by the agency, ex-
empts discharges of channeled stormwater runoff from
logging roads from the NPDES permitting scheme. As a
result, there is no need to reach petitioners’ alternative
argument that the conveyances in question are not
“pipe[s], ditch[es], channel[s], tunnel[s], conduit[s],” or any
other type of point source within the Act’s definition of the
term. §1362(14).
  For the reasons stated, the judgment of the Court of
Appeals is reversed, and the cases are remanded for pro-
16   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                        CENTER
                   Opinion of the Court

ceedings consistent with this opinion.
                                         It is so ordered.

  JUSTICE BREYER took no part in the consideration or
decision of these cases.
                 Cite as: 568 U. S. ____ (2013)            1

                   ROBERTS, C. J., concurring

SUPREME COURT OF THE UNITED STATES
                         _________________

                    Nos. 11–338 and 11–347
                         _________________


 DOUG DECKER, IN HIS OFFICIAL CAPACITY AS OREGON
       STATE FORESTER, ET AL., PETITIONERS
11–338                 v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER

GEORGIA-PACIFIC WEST, INC., ET AL., PETITIONERS
11–347               v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE NINTH CIRCUIT
                       [March 20, 2013]

   CHIEF JUSTICE ROBERTS, with whom JUSTICE ALITO
joins, concurring.
   The opinion concurring in part and dissenting in part
raises serious questions about the principle set forth in
Bowles v. Seminole Rock & Sand Co., 325 U. S. 410 (1945),
and Auer v. Robbins, 519 U. S. 452 (1997). It may be ap-
propriate to reconsider that principle in an appropriate
case. But this is not that case.
   Respondent suggested reconsidering Auer, in one sen-
tence in a footnote, with no argument. See Brief for Re-
spondent 42, n. 12. Petitioners said don’t do it, again in a
footnote. See Reply Brief for Petitioners in No. 11–338,
p. 4, n. 1; see also Turner Broadcasting System, Inc. v. FCC,
520 U. S. 180, 223–224 (1997) (declining to decide question
that received only “scant argumentation”). Out of 22
amicus briefs, only two—filed by dueling groups of law
professors—addressed the issue on the merits. See Brief
for Law Professors as Amici Curiae on the Propriety of
2    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE

                         CENTER

                  ROBERTS, C. J., concurring


Administrative Deference in Support of Respondent; Brief
for Law Professors as Amici Curiae in Support of Petition-
ers; see also FTC v. Phoebe Putney Health System, Inc.,
568 U. S. ___, ___, n. 4 (2013) (slip op., at 7, n. 4) (declining
to consider argument raised only by amicus).
   The issue is a basic one going to the heart of administra-
tive law. Questions of Seminole Rock and Auer deference
arise as a matter of course on a regular basis. The bar is
now aware that there is some interest in reconsidering
those cases, and has available to it a concise statement of
the arguments on one side of the issue.
   I would await a case in which the issue is properly
raised and argued. The present cases should be decided
as they have been briefed and argued, under existing
precedent.
                   Cite as: 568 U. S. ____ (2013)               1

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

SUPREME COURT OF THE UNITED STATES
                            _________________

                     Nos. 11–338 and 11–347
                            _________________


 DOUG DECKER, IN HIS OFFICIAL CAPACITY AS OREGON
       STATE FORESTER, ET AL., PETITIONERS
11–338                 v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER

GEORGIA-PACIFIC WEST, INC., ET AL., PETITIONERS
11–347               v.
 NORTHWEST ENVIRONMENTAL DEFENSE CENTER
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE NINTH CIRCUIT
                         [March 20, 2013]

   JUSTICE SCALIA, concurring in part and dissenting in
part.
   I join Parts I and II of the Court’s opinion; I agree that
these cases are not moot and that the District Court had
jurisdiction. I do not join Part III. The Court there gives
effect to a reading of EPA’s regulations that is not the
most natural one, simply because EPA says that it be-
lieves the unnatural reading is right. It does this, more-
over, even though the agency has vividly illustrated that it
can write a rule saying precisely what it means—by doing
just that while these cases were being briefed.
   Enough is enough.
                             I
  For decades, and for no good reason, we have been
giving agencies the authority to say what their rules
mean, under the harmless-sounding banner of “defer[ring]
to an agency’s interpretation of its own regulations.” Talk
America, Inc. v. Michigan Bell Telephone Co., 564 U. S.
2    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER
        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

___, ___ (2011) (SCALIA, J., concurring) (slip op., at 1).
This is generally called Seminole Rock or Auer deference.
See Bowles v. Seminole Rock & Sand Co., 325 U. S. 410
(1945); Auer v. Robbins, 519 U. S. 452 (1997).
   Two Terms ago, in my separate concurrence in Talk
America, I expressed doubts about the validity of this
practice. In that case, however, the agency’s interpreta-
tion of the rule was also the fairest one, and no party had
asked us to reconsider Auer. Today, however, the Court’s
deference to the agency makes the difference (note the
Court’s defensive insistence that the agency’s interpreta-
tion need not be “the best one,” ante, at 14). And respon-
dent has asked us, if necessary, to “ ‘reconsider Auer.’ ” I
believe that it is time to do so. See Brief for Respondent
42, n. 12; see also Brief for Law Professors on the Propri-
ety of Administrative Deference as Amici Curiae. This is
especially true because the circumstances of these cases
illustrate Auer’s flaws in a particularly vivid way.
   The canonical formulation of Auer deference is that we
will enforce an agency’s interpretation of its own rules
unless that interpretation is “plainly erroneous or incon-
sistent with the regulation.” Seminole Rock, supra, at 414.
But of course whenever the agency’s interpretation of the
regulation is different from the fairest reading, it is in that
sense “inconsistent” with the regulation. Obviously, that
is not enough, or there would be nothing for Auer to do. In
practice, Auer deference is Chevron deference applied to
regulations rather than statutes. See Chevron U. S. A.
Inc. v. Natural Resources Defense Council, Inc., 467 U. S.
837 (1984). The agency’s interpretation will be accepted if,
though not the fairest reading of the regulation, it is a
plausible reading—within the scope of the ambiguity that
the regulation contains.
   Our cases have not put forward a persuasive justifica-
tion for Auer deference. The first case to apply it, Semi-
nole Rock, offered no justification whatever—just the ipse
                   Cite as: 568 U. S. ____ (2013)               3

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

dixit that “the administrative interpretation . . . becomes
of controlling weight unless it is plainly erroneous or
inconsistent with the regulation.” 325 U. S., at 414. Our
later cases provide two principal explanations, neither of
which has much to be said for it. See generally Stephen-
son & Pogoriler, Seminole Rock’s Domain, 79 Geo. Wash.
L. Rev. 1449, 1454–1458 (2011). First, some cases say
that the agency, as the drafter of the rule, will have some
special insight into its intent when enacting it. E.g.,
Martin v. Occupational Safety and Health Review
Comm’n, 499 U. S. 144, 150–153 (1991). The implied
premise of this argument—that what we are looking for is
the agency’s intent in adopting the rule—is false. There is
true of regulations what is true of statutes. As Justice
Holmes put it: “[w]e do not inquire what the legislature
meant; we ask only what the statute means.” The Theory
of Legal Interpretation, 12 Harv. L. Rev. 417, 419 (1899).
Whether governing rules are made by the national legisla-
ture or an administrative agency, we are bound by what
they say, not by the unexpressed intention of those who
made them.
   The other rationale our cases provide is that the agency
possesses special expertise in administering its “ ‘complex
and highly technical regulatory program.’ ” See, e.g.,
Thomas Jefferson Univ. v. Shalala, 512 U. S. 504, 512
(1994). That is true enough, and it leads to the conclu-
sion that agencies and not courts should make regula-
tions. But it has nothing to do with who should interpret
regulations—unless one believes that the purpose of inter-
pretation is to make the regulatory program work in a fashion
that the current leadership of the agency deems effective.
Making regulatory programs effective is the purpose of
rulemaking, in which the agency uses its “special exper-
tise” to formulate the best rule. But the purpose of inter-
pretation is to determine the fair meaning of the rule—to
“say what the law is,” Marbury v. Madison, 1 Cranch 137,
4    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J. 


177 (1803). Not to make policy, but to determine what
policy has been made and promulgated by the agency, to
which the public owes obedience. Indeed, since the leader-
ship of agencies (and hence the policy preferences of agen-
cies) changes with Presidential administrations, an agency
head can only be sure that the application of his “special
expertise” to the issue addressed by a regulation will be
given effect if we adhere to predictable principles of textual
interpretation rather than defer to the “special expertise”
of his successors. If we take agency enactments as writ-
ten, the Executive has a stable background against which
to write its rules and achieve the policy ends it thinks
best.
   Another conceivable justification for Auer deference,
though not one that is to be found in our cases, is this: If it
is reasonable to defer to agencies regarding the meaning of
statutes that Congress enacted, as we do per Chevron, it is
a fortiori reasonable to defer to them regarding the mean-
ing of regulations that they themselves crafted. To give an
agency less control over the meaning of its own regula-
tions than it has over the meaning of a congressionally
enacted statute seems quite odd.
   But it is not odd at all. The theory of Chevron (take it or
leave it) is that when Congress gives an agency authority
to administer a statute, including authority to issue in-
terpretive regulations, it implicitly accords the agency a
degree of discretion, which the courts must respect, re-
garding the meaning of the statute. See Smiley v. Citi-
bank (South Dakota), N. A., 517 U. S. 735, 740–741 (1996).
While the implication of an agency power to clarify the
statute is reasonable enough, there is surely no congres-
sional implication that the agency can resolve ambiguities
in its own regulations. For that would violate a funda-
mental principle of separation of powers—that the power
to write a law and the power to interpret it cannot rest
in the same hands. “When the legislative and executive
                   Cite as: 568 U. S. ____ (2013)               5

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

powers are united in the same person . . . there can be no
liberty; because apprehensions may arise, lest the same
monarch or senate should enact tyrannical laws, to exe-
cute them in a tyrannical manner.” Montesquieu, Spirit
of the Laws bk. XI, ch. 6, pp. 151–152 (O. Piest ed., T.
Nugent transl. 1949). Congress cannot enlarge its own
power through Chevron—whatever it leaves vague in the
statute will be worked out by someone else. Chevron rep-
resents a presumption about who, as between the Execu-
tive and the Judiciary, that someone else will be. (The
Executive, by the way—the competing political branch—is
the less congenial repository of the power as far as Con-
gress is concerned.) So Congress’s incentive is to speak as
clearly as possible on the matters it regards as important.
   But when an agency interprets its own rules—that is
something else. Then the power to prescribe is augmented
by the power to interpret; and the incentive is to speak
vaguely and broadly, so as to retain a “flexibility” that
will enable “clarification” with retroactive effect. “It is per-
fectly understandable” for an agency to “issue vague regula-
tions” if doing so will “maximiz[e] agency power.” Thomas
Jefferson Univ., supra, at 525 (THOMAS, J., dissenting).
Combining the power to prescribe with the power to inter-
pret is not a new evil: Blackstone condemned the practice
of resolving doubts about “the construction of the Roman
laws” by “stat[ing] the case to the emperor in writing, and
tak[ing] his opinion upon it.” 1 W. Blackstone, Commen-
taries on the Laws of England 58 (1765). And our Consti-
tution did not mirror the British practice of using the
House of Lords as a court of last resort, due in part to the
fear that he who has “agency in passing bad laws” might
operate in the “same spirit” in their interpretation. The
Federalist No. 81, pp. 543–544 (J. Cooke ed. 1961). Auer
deference encourages agencies to be “vague in framing
regulations, with the plan of issuing ‘interpretations’ to
create the intended new law without observance of notice
6    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J. 


and comment procedures.” Anthony, The Supreme Court
and the APA: Sometimes They Just Don’t Get It, 10 Ad-
min. L. J. Am. U. 1, 11–12 (1996). Auer is not a logical
corollary to Chevron but a dangerous permission slip for
the arrogation of power. See Talk America, 564 U. S., at
___ (SCALIA, J., concurring) (slip op., at 2–3); Manning,
Constitutional Structure and Judicial Deference to Agency
Interpretations of Agency Rules, 96 Colum. L. Rev. 612
(1996).
   It is true enough that Auer deference has the same
beneficial pragmatic effect as Chevron deference: The
country need not endure the uncertainty produced by
divergent views of numerous district courts and courts of
appeals as to what is the fairest reading of the regulation,
until a definitive answer is finally provided, years later, by
this Court. The agency’s view can be relied upon, unless it
is, so to speak, beyond the pale. But the duration of the
uncertainty produced by a vague regulation need not be as
long as the uncertainty produced by a vague statute. For
as soon as an interpretation uncongenial to the agency is
pronounced by a district court, the agency can begin the
process of amending the regulation to make its meaning
entirely clear. The circumstances of this case demonstrate
the point. While these cases were being briefed before us,
EPA issued a rule designed to respond to the Court of
Appeals judgment we are reviewing. See 77 Fed. Reg.
72974 (2012) (to be codified in 40 CFR pt. 122, sub pt. B).
It did so (by the standards of such things) relatively
quickly: The decision below was handed down in May 2011,
and in December 2012 the EPA published an amended
rule setting forth in unmistakable terms the position it ar-
gues here. And there is another respect in which a lack of
Chevron-type deference has less severe pragmatic conse-
quences for rules than for statutes. In many cases, when
an agency believes that its rule permits conduct that the
text arguably forbids, it can simply exercise its discretion
                   Cite as: 568 U. S. ____ (2013)               7

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

not to prosecute. That is not possible, of course, when, as
here, a party harmed by the violation has standing to
compel enforcement.
   In any case, however great may be the efficiency gains
derived from Auer deference, beneficial effect cannot jus-
tify a rule that not only has no principled basis but contra-
venes one of the great rules of separation of powers: He
who writes a law must not adjudge its violation.
                              II
   I would therefore resolve these cases by using the famil-
iar tools of textual interpretation to decide: Is what the
petitioners did here proscribed by the fairest reading of
the regulations? What they did was to channel storm-
water runoff from logging roads without a permit. To
decide whether that was permissible we must answer one,
and possibly two, questions: First, was the stormwater
discharged from a “point source”? If not, no permit was
required. But if so, we face the second question: Were the
stormwater discharges exempt from the permit require-
ment because they were not “associated with industrial
activity”? The fairest reading of the statute and regula-
tions is that these discharges were from point sources, and
were associated with industrial activity.
                              A
  The Clean Water Act generally prohibits discharging
pollution without a permit from what it calls a “point
source.” 33 U. S. C. §1311(a). A “point source” is defined
as “any discernible, confined and discrete conveyance,
including but not limited to any pipe, ditch, channel,
tunnel, conduit,” and several other things. §1362(14). The
stormwater here was discharged from logging roads
through a series of pipes, ditches, and channels—all items
expressly named in the definition.
  EPA argues that the Silvicultural Rule, 40 CFR
8    DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J. 


§122.27(b)(1) (2006), excludes from the definition of
“[s]ilvicultural point source” “harvesting operations . . .
from which there is natural runoff.” This is relevant, says
the agency, because that rule specifies that only
“[s]ilvicultural point sources, as defined in this section,”
are “point sources subject to the . . . permit program.”
§122.27(a). In EPA’s view, the stormwater here is “natu-
ral runoff.”
   But are stormwater discharges “natural runoff ” when
they are channeled through manmade pipes and ditches,
and carry with them manmade pollutants from manmade
forest roads? It is not obvious that this is so—as the agency
agrees. See Brief for United States as Amicus Curiae 19
(the rule’s “reference to ‘natural runoff ’ associated with
logging roads neither clearly encompasses nor clearly
excludes the sort of channeled runoff that is at issue in
this case”). In my view, giving the term the agency’s
interpretation would contradict the statute’s definition of
“point source,” which explicitly includes any “pipe, ditch,
channel, tunnel, [and] conduit.” Applying the interpretive
presumption of validity—the canon that we are to “prefe[r]
the meaning that preserves to the meaning that destroys,”
Panama Refining Co. v. Ryan, 293 U. S. 388, 439 (1935)
(Cardozo, J., dissenting)—I would hold that the regula-
tion’s exclusion of “natural runoff ” does not reach the
situation here. The stormwater discharges came from point
sources, because they flowed out of artificial “pipe[s],”
“ditch[es],” and “channel[s],” 33 U. S. C. §1362(14), and
were thus not “natural runoff ” from a logging opera-
tion, 40 CFR §122.27(b)(1) (emphasis added).
                           B
  Many point-source stormwater discharges are nonethe-
less exempt from the usual permitting requirement. See
33 U. S. C. §1342(p). This exemption, however, does not
reach discharges “associated with industrial activity.”
                    Cite as: 568 U. S. ____ (2013)               9

         SCALIA, J., concurring inof SCALIA,dissenting in part
                         Opinion part and J.

Ibid. EPA has enacted a rule defining what it means for
stormwater discharges to be “associated with” industrial
activity, and what activities count as “industrial.” 40 CFR
§122.26(b)(14).
   The regulation sets out eleven “categories of industries”;
as to those industries, discharges are “associated with
industrial activity” if they come from sites used for “trans-
portation” of “any raw material.” Ibid. The forest roads at
issue here are used to transport raw material (logs); the
only question is whether logging is a “categor[y] of in-
dustr[y]” enumerated in the definition. It is: The second of
the listed “categories of facilities” is “[f]acilities classified
as Standard Industrial Classifications 24 (except 2434).”
§122.26(b)(14)(ii). Opening one’s hymnal to Standard
Industrial Classification 24 (“Lumber and Wood Products,
Except Furniture”), one finds that the first industry group
listed, No. 2411, is “Logging”—defined as “[e]stablish-
ments primarily engaged in cutting timber.” 2 App. 64.
(As if that were not clear enough, an illustrative product of
this industry is helpfully listed: “Logs.”) That, I would
think, is that.
   EPA disagrees, and the Court gives the agency’s posi-
tion Auer deference, but that reading is certainly not the
most natural one. The Court relies heavily on the fact
that the definition of “[s]torm water discharge associ-
ated with industrial activity” requires that the discharge
be “directly related to manufacturing, processing or
raw materials storage areas at an industrial plant,”
§122.26(b)(14). The crucial question this definition pre-
sents is whether the concluding phrase “at an industrial
plant” limits only the last noun phrase (“raw materials
storage areas”) or also the two preceding nouns (“manufac-
turing” and “processing”). The canon of interpretation
known as the rule of the last antecedent states that “a
limiting clause or phrase . . . should ordinarily be read as
modifying only the noun or phrase that it immediately
10   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER
        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

follows.” Barnhart v. Thomas, 540 U. S. 20, 26 (2003). If
a statute provides that “it shall be unlawful to possess a
grenade launcher, a fully-automatic weapon, or a shotgun
with a barrel shorter than 12 inches,” that does not mean
that a grenade launcher with a barrel longer than 12
inches is legal. Application of the canon would mean that
“at an industrial plant” modifies only “raw materials
storage areas,” and therefore that “manufacturing” and
“processing” anywhere, including in the forest, would be
“associated with industrial activity.” (Standard Industrial
Classification 24 categorizes logging as a manufacturing
business, and these discharges are therefore “directly
related to manufacturing.”)
   Like all canons of interpretation, the rule of the last
antecedent can be overcome by textual indication of
contrary meaning. But that does not exist here. To the
contrary, the enumerated categories of industries to
which the term “industrial activity” applies reinforce the
proposition that “at an industrial plant” does not
modify “manufacturing” or “processing.” The term in-
cludes (in addition to logging) “active or inactive mining
operations,” §122.26(b)(14)(iii); “[l]andfills” and “open
dumps,” §122.26(b)(14)(v); “automobile junkyards,”
§122.26(b)(14)(vi); and “[c]onstruction activity including
clearing, grading and excavation,” §122.26(b)(14)(x).
Those industries and activities (while related to manufac-
turing and processing) virtually never take place at any-
thing like what one might describe as a “plant.” The rule
of the last antecedent is therefore confirmed as the correct
guide to meaning here: “at an industrial plant” limits only
“raw materials storage areas.”
   EPA also insists, Brief for United States as Amicus
Curiae 24, that the regulation reaches only “ ‘traditional’ ”
sources of industrial stormwater, such as sawmills. But
Standard Industrial Classification 24 has a specific sub-
category (No. 242) that is “Sawmills and Planing Mills.” 2
                   Cite as: 568 U. S. ____ (2013)               11

        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

App. 64. The rule is not so limited, reaching by its terms
“Standard Industrial Classificatio[n] 24 (except 2434).”
§122.26(b)(14)(ii). The explicit carving-out of No. 2434 is
telling: Why EPA chose to exclude “establishments pri-
marily engaged in manufacturing wood kitchen cabinet
and wood bathroom vanities” from the definition of indus-
trial stormwater, I do not know—but the picayune nature
of the exclusion gives lie to the idea that the rule’s scope
ought to be decided by a rough sense of its gestalt. If EPA
had meant to reach only sawmills, it quite obviously knew
how to do so.
   Finally, the Court believes that Standard Industrial
Classification 24’s reference to “establishments” “sug-
gest[s] industrial sites more fixed and permanent than
outdoor timber-harvesting operations.” Ante, at 13. Not
so. The Standard Industrial Classification uses “es-
tablishments” throughout to refer to business entities
in general; for example, Classification 2411 refers to
“[e]stablishments primarily engaged in cutting timber,”
which includes “producing wood chips in the field.” 2 App.
64. I cannot imagine what kind of “fixed and permanent”
industrial site the Court and EPA imagine will be “produc-
ing wood chips in the field.” And the Court’s final point,
ante, at 13—that the regulatory definition of “industrial
activity” uses the word “facilities”—cuts the other way:
EPA regulations define “facility” to include “any . . . ‘point
source.’ ” 40 CFR §122.2; see, e.g., §122.26(b)(14)(iii) (re-
ferring to mines as “facilities”).
   The agency also assures us that its intent (Brief for
United States as Amicus Curiae 25) was to reach a more
limited subset of logging activities, an intent that it be-
lieves can essentially float free from the text of the rele-
vant rule. In the end, this is the real meat of the matter:
EPA states that it simply did not mean to require permits
for the discharges at issue here. And the Court is willing
to credit that intent, even given what I think has been
12   DECKER v. NORTHWEST ENVIRONMENTAL DEFENSE
                              CENTER
        SCALIA, J., concurring inof SCALIA,dissenting in part
                        Opinion part and J.

amply demonstrated to be a contrary text.
                        *    *     *
  Because the fairest reading of the agency’s rules pro-
scribes the conduct at issue in these cases, I would affirm
the judgment below. It is time for us to presume (to coin a
phrase) that an agency says in a rule what it means, and
means in a rule what it says there.
