(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

LOS ANGELES COUNTY FLOOD CONTROL DISTRICT
v. NATURAL RESOURCES DEFENSE COUNCIL, INC.,
                  ET AL.

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

   No. 11–460.      Argued December 4, 2012—Decided January 8, 2013
Petitioner Los Angeles County Flood Control District (District) operates
  a “municipal separate storm sewer system” (MS4), a drainage system
  that collects, transports, and discharges storm water. Because storm
  water is often heavily polluted, the Clean Water Act (CWA) and its
  implementing regulations require certain MS4 operators to obtain a
  National Pollutant Discharge Elimination System (NPDES) permit
  before discharging storm water into navigable waters. The District
  has such a permit for its MS4. Respondents Natural Resources De-
  fense Council, Inc. (NRDC) and Santa Monica Baykeeper (Baykeeper)
  filed a citizen suit against the District and others under §505 of the
  CWA, 33 U. S. C. §1365, alleging, among other things, that water-
  quality measurements from monitoring stations within the Los Ange-
  les and San Gabriel Rivers demonstrated that the District was violat-
  ing the terms of its permit. The District Court granted summary
  judgment to the District on these claims, concluding that the record
  was insufficient to warrant a finding that the MS4 had discharged
  storm water containing the standards-exceeding pollutants detected
  at the downstream monitoring stations. The Ninth Circuit reversed
  in relevant part. The court held that the District was liable for the
  discharge of pollutants that, in the court’s view, occurred when the
  polluted water detected at the monitoring stations flowed out of the
  concrete-lined portions of the rivers, where the monitoring stations
  are located, into lower, unlined portions of the same rivers.
Held: The flow of water from an improved portion of a navigable wa-
 terway into an unimproved portion of the same waterway does not
2         LOS ANGELES COUNTY FLOOD CONTROL DIST. v.
          NATURAL RESOURCES DEFENSE COUNCIL, INC.

                          Syllabus


    qualify as a “discharge of a pollutant” under the CWA. See South
    Fla. Water Management Dist. v. Miccosukee Tribe, 541 U. S. 95, 109–
    112 (holding that the transfer of polluted water between “two parts of
    the same water body” does not constitute a discharge of pollutants
    under the CWA). The Ninth Circuit’s decision cannot be squared
    with this holding.
      The NRDC and Baykeeper alternatively argue that, based on the
    terms of the District’s NPDES permit, the exceedances detected at
    the monitoring stations sufficed to establish the District’s liability
    under the CWA for its upstream discharges. This argument, which
    failed below, is not embraced within the narrow question on which
    certiorari was granted. The Court therefore does not address it.
    Pp. 3–5.
673 F. 3d 880, reversed and remanded.

  GINSBURG, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and SCALIA, KENNEDY, THOMAS, BREYER, SOTOMAYOR, and KAGAN,
JJ., joined. ALITO, J., concurred in the judgment.
                        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
                                   _________________

                                   No. 11–460
                                   _________________


LOS ANGELES COUNTY FLOOD CONTROL DISTRICT 

 PETITIONER v. NATURAL RESOURCES DEFENSE

            COUNCIL, INC., ET AL. 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE NINTH CIRCUIT

                               [January 8, 2013]


  JUSTICE GINSBURG delivered the opinion of the Court.
  The Court granted review in this case limited to a single
question: Under the Clean Water Act (CWA), 86 Stat.
816, as amended, 33 U. S. C. §1251 et seq., does the flow of
water out of a concrete channel within a river rank as a
“discharge of a pollutant”? In this Court, the parties and
the United States as amicus curiae agree that the answer
to this question is “no.” They base this accord on South
Fla. Water Management Dist. v. Miccosukee Tribe, 541
U. S. 95, 109–112 (2004), in which we accepted that pump-
ing polluted water from one part of a water body into
another part of the same body is not a discharge of pol-
lutants under the CWA. Adhering to the view we took in
Miccosukee, we hold that the parties correctly answered
the sole question presented in the negative. The decision
in this suit rendered by the Court of Appeals for the Ninth
Circuit is inconsistent with our determination. We there-
fore reverse that court’s judgment.
  Petitioner Los Angeles County Flood Control District
(District) operates a “municipal separate storm sewer
2      LOS ANGELES COUNTY FLOOD CONTROL DIST. v.
       NATURAL RESOURCES DEFENSE COUNCIL, INC.

                    Opinion of the Court 


system” (MS4)—a drainage system that collects, trans-
ports, and discharges storm water.            See 40 CFR
§122.26(b)(8) (2012). See also §122.26(b)(13) (“Storm
water means storm water runoff, snow melt runoff, and
surface runoff and drainage.”). Because storm water is
often heavily polluted, see 64 Fed. Reg. 68724–68727
(1999), the CWA and its implementing regulations require
the operator of an MS4 serving a population of at least
100,000 to obtain a National Pollutant Discharge Elimina-
tion System (NPDES) permit before discharging storm
water into navigable waters. See 33 U. S. C. §§1311(a),
1342(p)(2)(C), and (D); 40 CFR §§122.26(a)(3), (b)(4), (b)(7).
The District first obtained a NPDES permit for its MS4 in
1990; thereafter, the permit was several times renewed.
Natural Resources Defense Council, Inc. v. County of Los
Angeles, 673 F. 3d 880, 886 (CA9 2011).
   Respondents Natural Resources Defense Council, Inc.
(NRDC) and Santa Monica Baykeeper (Baykeeper) filed
a citizen suit against the District and several other de-
fendants under §505 of the CWA, 33 U. S. C. §1365. They
alleged, among other things, that water-quality measure-
ments from monitoring stations located within the Los
Angeles and San Gabriel Rivers demonstrated that the
District was violating the terms of its permit.
   The District Court granted summary judgment to the
District on these claims. It was undisputed, the District
Court acknowledged, that “data from the Los Angeles
River and San Gabriel River [monitoring] stations indi-
cate[d] that water quality standards ha[d] repeatedly been
exceeded for a number of pollutants, including aluminum,
copper, cyanide, fecal coliform bacteria, and zinc.” App. to
Pet. for Cert. 108. But numerous entities other than the
District, the court added, discharge into the rivers up-
stream of the monitoring stations. See id., at 115–116.
See also 673 F. 3d, at 889 (observing that the pollutants of
“thousands of permitted dischargers” reach the rivers).
                 Cite as: 568 U. S. ____ (2013)            3

                     Opinion of the Court

The record was insufficient, the District Court concluded,
to warrant a finding that the District’s MS4 had dis-
charged storm water containing the standards-exceeding
pollutants detected at the downstream monitoring
stations.
   The Ninth Circuit reversed in relevant part. The moni-
toring stations for the Los Angeles and San Gabriel Riv-
ers, the Court of Appeals said, are located in “concrete
channels” constructed for flood-control purposes. Id., at
900. See also id., at 889 (describing the monitoring
stations’ location). Based on this impression, the Court of
Appeals held that a discharge of pollutants occurred under
the CWA when the polluted water detected at the monitor-
ing stations “flowed out of the concrete channels” and
entered downstream portions of the waterways lacking
concrete linings. Id., at 900. Because the District exer-
cises control over the concrete-lined portions of the rivers,
the Court of Appeals held, the District is liable for the
discharges that, in the appellate court’s view, occur when
water exits those concrete channels. See id., at 899–901.
   We granted certiorari on the following question: Under
the CWA, does a “discharge of pollutants” occur when
polluted water “flows from one portion of a river that is
navigable water of the United States, through a concrete
channel or other engineered improvement in the river,”
and then “into a lower portion of the same river”? Pet.
for Cert. i. See 567 U. S. ___ (2012). As noted above,
see supra, at 1, the parties, as well as the United States
as amicus curiae, agree that the answer to this question
is “no.”
   That agreement is hardly surprising, for we held in
Miccosukee that the transfer of polluted water between
“two parts of the same water body” does not constitute a
discharge of pollutants under the CWA. 541 U. S., at 109–
112. We derived that determination from the CWA’s text,
which defines the term “discharge of a pollutant” to mean
4       LOS ANGELES COUNTY FLOOD CONTROL DIST. v.
        NATURAL RESOURCES DEFENSE COUNCIL, INC.

                     Opinion of the Court 


“any addition of any pollutant to navigable waters from
any point source.” 33 U. S. C. §1362(12) (emphasis added).
Under a common understanding of the meaning of the
word “add,” no pollutants are “added” to a water body
when water is merely transferred between different por-
tions of that water body. See Webster’s Third New Inter-
national Dictionary 24 (2002) (“add” means “to join, annex,
or unite (as one thing to another) so as to bring about
an increase (as in number, size, or importance) or so as to
form one aggregate”). “As the Second Circuit [aptly] put it
. . . , ‘[i]f one takes a ladle of soup from a pot, lifts it above
the pot, and pours it back into the pot, one has not “added”
soup or anything else to the pot.’ ” Miccosukee, 541 U. S.,
at 109–110 (quoting Catskill Mountains Chapter of Trout
Unlimited, Inc. v. New York, 273 F. 3d 481, 492 (CA2
2001)).
    In Miccosukee, polluted water was removed from a ca-
nal, transported through a pump station, and then de-
posited into a nearby reservoir. 541 U. S., at 100. We
held that this water transfer would count as a discharge of
pollutants under the CWA only if the canal and the reser-
voir were “meaningfully distinct water bodies.” Id., at
112. It follows, a fortiori, from Miccosukee that no dis-
charge of pollutants occurs when water, rather than being
removed and then returned to a water body, simply flows
from one portion of the water body to another. We hold,
therefore, that the flow of water from an improved portion
of a navigable waterway into an unimproved portion of
the very same waterway does not qualify as a discharge of
pollutants under the CWA. Because the decision below
cannot be squared with that holding, the Court of Appeals’
judgment must be reversed.1
——————
  1 The NRDC, Baykeeper, and the United States contend—contrary to

the District—that the Court of Appeals understood that no discharge of
pollutants occurs when water flows from an improved into an unim-
                     Cite as: 568 U. S. ____ (2013)                     5

                          Opinion of the Court

   The NRDC and Baykeeper urge that the Court of Ap-
peals reached the right result, albeit for the wrong reason.
The monitoring system proposed by the District and writ-
ten into its permit showed numerous instances in which
water-quality standards were exceeded. Under the per-
mit’s terms, the NRDC and Baykeeper maintain, the ex-
ceedances detected at the instream monitoring stations
are by themselves sufficient to establish the District’s
liability under the CWA for its upstream discharges. See
Brief for Respondents 33–62.2 This argument failed be-
low. See 673 F. 3d, at 898, 901; App. to Pet. for Cert. 100–
102. It is not embraced within, or even touched by,
the narrow question on which we granted certiorari. We
therefore do not address, and indicate no opinion on, the
issue the NRDC and Baykeeper seek to substitute for the
question we took up for review.
                      *    *      *
  For the reasons stated, the judgment of the Court of
Appeals for the Ninth Circuit is reversed, and the case is
remanded.
                                           It is so ordered.

JUSTICE ALITO concurs in the judgment.
——————
proved portion of a navigable waterway. They suggest that the Court of
Appeals misperceived the facts, erroneously believing that the monitor-
ing stations for the Los Angeles and San Gabriel Rivers “were sampling
water from a portion of the MS4 that was distinct from the rivers
themselves and from which discharges through an outfall to the rivers
subsequently occurred.” Brief for United States as Amicus Curiae 18.
See also Brief for Respondents 30–31 (“The court of appeals’ statements
suggest it believed the monitoring stations sampled polluted storm-
water from the District’s MS4 before, not after, discharge to the Los
Angeles and San Gabriel Rivers.”). Whatever the source of the Court of
Appeals’ error, all parties agree that the court’s analysis was erroneous.
  2 Shortly before oral argument in this case, a renewed permit was

approved for the District’s MS4. Unlike the District’s prior permit,
which required only instream monitoring, the renewed permit requires
end-of-pipe monitoring at individual MS4 discharge points. See id., at
20–21; Reply Brief 5, n. 2.
