                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

SAN FRANCISCO BAYKEEPER;               
CITIZENS COMMITTEE TO
COMPLETE THE REFUGE; MICHAEL R.
LOZEAU,                                     No. 04-17554
              Plaintiffs-Appellees,
                                             D.C. No.
               v.                          CV-96-02161-SI
CARGILL SALT DIVISION; CARGILL
INC.,
           Defendants-Appellants.
                                       

SAN FRANCISCO BAYKEEPER;               
CITIZENS COMMITTEE TO
COMPLETE THE REFUGE,
             Plaintiffs-Appellants,
                                            No. 05-15051
              and
MICHAEL R. LOZEAU,                           D.C. No.
                                           CV-96-02161-SI
                          Plaintiff,
                                             OPINION
               v.
CARGILL SALT DIVISION; CARGILL
INC.,
            Defendants-Appellees.
                                       
       Appeal from the United States District Court
          for the Northern District of California
      Susan Yvonne Illston, District Judge, Presiding

                 Argued and Submitted
      September 27, 2006—San Francisco, California
                            2665
2666 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
                   Filed March 8, 2007

 Before: William C. Canby, Jr., Michael Daly Hawkins, and
             Ronald M. Gould, Circuit Judges.

                 Opinion by Judge Canby
2668 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION


                        COUNSEL

John F. Barg, Barg, Coffin, Lewis & Trapp, LLP, San Fran-
cisco, California, for the defendants-appellants-cross-
appellees.

Daniel Purcell, Keker & Van Nest, LLP, San Francisco, Cali-
fornia, for the plaintiffs-appellees-cross-appellants.

Gregory T. Broderick, Pacific Legal Foundation, Sacramento,
California; Scott M. DuBoff, Wright & Talisman, PC, Wash-
ington, D.C.; Virginia S. Albrecht, Hunton & Williams, LLP,
Washington, D.C.; James Murphy, National Wildlife Federa-
tion, Montpelier, Vermont; Katherine J. Barton, United States
Department of Justice, Environment & Natural Resources
Division, Washington, D.C., for the amici curiae.
      SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2669
                          OPINION

CANBY, Circuit Judge:

   San Francisco Baykeeper and Citizens Committee to Com-
plete the Refuge (collectively “Baykeeper”) filed this citizen
suit under the Clean Water Act, 33 U.S.C. § 1251 et seq.,
(“CWA” or “the Act”) against Cargill Salt Division and Car-
gill, Incorporated (collectively “Cargill”). Baykeeper alleged
that Cargill discharged pollutants into “waters of the United
States” without a permit. The body of water into which Car-
gill allegedly discharged waste is a non-navigable, intrastate
pond (“the Pond”), not determined to be a “wetland,” that col-
lects polluted runoff within Cargill’s waste containment facil-
ity located near the southeastern edge of San Francisco Bay.
The district court granted summary judgment in favor of
Baykeeper after determining that the Pond qualifies as a
“water[ ] of the United States” because it is adjacent to a pro-
tected water of the United States (Mowry Slough). Cargill
then brought this appeal. Because we conclude that mere adja-
cency provides a basis for CWA coverage only when the rele-
vant waterbody is a “wetland,” and no other reason for CWA
coverage of Cargill’s Pond is supported by evidence or is
properly before us, we reverse the district court’s summary
judgment.

                         Background

   Cargill and its predecessors have conducted salt-making
operations at the edge of San Francisco Bay, in Alameda
County, California, since the 1860’s. In 1979, the United
States acquired some 15,000 acres of Cargill’s lands for inclu-
sion in the Don Edwards San Francisco Bay Wildlife Refuge
(“the Refuge”). Cargill retained an easement over 12,000
acres that permits it to continue its salt-making operation.

  Cargill produces salt by evaporating water from the Bay in
a series of ponds. The harvesting and refinement of the salt
2670 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
results in the production of waste residue that is heavily saline
and contains other pollutants. Cargill maintains within the
Refuge a 17-acre waste containment facility that it uses for
disposal of salt-processing residue. The northern portion of
the disposal site (the “upper elevation”) contains a pile of
uncovered waste several acres in size (“the Pile”). During
storms, rainwater carries residue from the upper elevation
(including the Pile) to the southern portion of the site (the
“lower elevation”) where it drains into the non-navigable
Pond. An earthen levee separates the southern edge of the
Pond from Mowry Slough, a navigable tributary of San Fran-
cisco Bay. The parties agree that Mowry Slough is a “water[ ]
of the United States.”

   The horizontal distance between the edge of the Slough and
the edge of the Pond varies considerably depending on the
tide. At low tide, the Pond and the Slough are separated by as
much as 125 feet, including the surrounding wetlands. At high
tide, however, Slough water inundates the wetlands up to the
levee and has, on some occasions, overtopped the levee and
flowed into the Pond. While there is no evidence in the record
that liquid has ever flowed from the Pond to the Slough, the
district court made no specific rulings on that issue. Cargill
from time to time pumps waste water away from the Pond to
prevent the level of the Pond from approaching the top of the
levee.

   In 1996, Baykeeper filed a citizen suit pursuant to 33
U.S.C. § 1365 against Cargill, stating various claims under
the CWA arising from Cargill’s alleged unpermitted dis-
charge of pollution into “waters of the United States” (the
Pond). From the beginning, the parties have disputed whether
the Pond is within the coverage of the CWA.

   In its first motion for summary judgment, Baykeeper
alleged that the Pond is a “water[ ] of the United States” under
the “Migratory Bird Rule” of the Environmental Protection
Agency (“the EPA”), 53 Fed. Reg. 20,764, 20,765 (June 6,
        SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2671
1988), because it is used intermittently as habitat by migratory
birds. The district court agreed and granted summary judg-
ment in favor of Baykeeper on two claims.1 While appeals
were pending here, however, the Supreme Court issued its
decision in Solid Waste Agency of Northern Cook County v.
United States Army Corps of Engineers (“SWANCC”), 531
U.S. 159 (2001), holding that the identical Migratory Bird
Rule of the Army Corps of Engineers (“the Corps), when
applied to isolated intrastate waters, exceeded the Corps’
authority under the CWA. Id. at 174. In light of SWANCC, we
vacated the district court’s summary judgment and remanded
for consideration of whether alternative grounds exist for
CWA jurisdiction. San Francisco Baykeeper v. Cargill Salt
Div., 263 F.3d 963 (9th Cir. 2001).

   On remand, Baykeeper again moved for summary judg-
ment, this time advancing the theory that the Pond is a
“water[ ] of the United States” because it is adjacent to
Mowry Slough. Cargill opposed the motion, arguing that,
under controlling regulations, adjacency provides a basis for
CWA coverage only in the case of wetlands. Baykeeper has
apparently never argued or presented evidence that the Pond
qualifies as a “wetland” under the applicable regulatory defi-
nition. See 40 C.F.R. § 122.2 (2006).

   The district court granted summary judgment a second time
in favor of Baykeeper after determining that “bodies of water
that are adjacent to navigable waters are ‘waters of the United
States’ and are therefore protected under the Clean Water
Act.” Noting that adjacent wetlands qualify for CWA protec-
tion under the applicable regulations and Supreme Court pre-
  1
   The district court granted summary judgment that Cargill violated 33
U.S.C. §§ 1311 and 1342(p)(2)(B) by discharging stormwater associated
with industrial activity into “waters of the United States,” and that Cargill
violated 33 U.S.C. § 1311 by discharging non-stormwater pollutants into
“waters of the United States.” Following the summary judgment ruling,
Baykeeper dismissed its remaining claims with prejudice.
2672 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
cedent, the court reasoned that “the same characteristics that
justif[y] protection of adjacent wetlands . . . apply as well to
adjacent ponds.” In support of its determination that the Pond
is a water of the United States, the district court found as
undisputed facts that: (1) “the Pond was adjacent to Mowry
Slough at the time that the suit was filed”; (2) “the soils
between the Pond and Mowry Slough are saturated”; and (3)
“the berm between the Pond and Mowry Slough leaked and
allowed Slough water to enter the Pond at high tide.”2

   The parties subsequently entered into a settlement agree-
ment setting forth potential remedies contingent on further
proceedings, and preserving the right to appeal certain issues
(including the district court’s finding of CWA jurisdiction
based on adjacency). As part of the agreement, Baykeeper
waived the right “now or in the future” to assert “any theories
of CWA jurisdiction over the Site (including the Pond), other
than the Adjacent Waters Theory upon which the District
Court based its Jurisdictional Ruling.” The district court
issued a final judgment incorporating the terms of the settle-
ment agreement, and this appeal followed.

              Jurisdiction and Standard of Review

   We have jurisdiction under 28 U.S.C. § 1291. We review
de novo the district court’s grant of summary judgment that
the Pond is a “water[ ] of the United States.” Baccarat Fre-
mont Developers, LLC v. United States Army Corps of Eng’rs,
425 F.3d 1150, 1153 (9th Cir. 2005).
  2
    In a separate summary judgment ruling, the district court held that it
lacked jurisdiction to order removal of that portion of the Pile created
before 1991 because: (1) Baykeeper’s 1996 “notice” letter failed to pro-
vide the requisite specificity concerning pre-1991 discharges; and (2) the
five-year limitations period in 28 U.S.C. § 2462 barred relief for any time
prior to five years preceding the filing of the complaint. Baykeeper filed
a cross-appeal arguing that the district court erred in declining to order
removal of pre-1991 discharges. Because we conclude that the district
court erred in determining that the Pond is a “water[ ] of the United
States,” we do not reach the issues raised in Baykeeper’s cross-appeal.
       SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2673
                              Discussion

   We conclude that the district court improperly expanded
the regulatory definition of “waters of the United States”
when it held that bodies of water that are adjacent to naviga-
ble waters are subject to the CWA by reason of that adja-
cency. Our conclusion is based on the CWA, the regulations
promulgated by the agencies responsible for administering it,
and the decisions of the Supreme Court addressing the reach
of the Act and its regulations.

   [1] Congress passed the CWA in 1972 “to restore and
maintain the chemical, physical, and biological integrity of
the Nation’s waters.” 86 Stat. 816, codified at 33 U.S.C.
§ 1251(a). One of its principal provisions prohibits the unper-
mitted discharge of pollutants into “navigable waters.” 33
U.S.C. § 1311(a). The term “navigable waters” is defined
elsewhere in the Act to mean “waters of the United States.”
Id. § 1362(7).

   [2] By not defining further the meaning of “waters of the
United States,” Congress implicitly delegated policy-making
authority to the EPA and the Corps, the agencies charged with
the CWA’s administration. See Chevron, USA Inc. v. Natural
Res. Def. Council, 467 U.S. 837, 844 (1984) (holding that
congressional delegation to an agency may be implicit).3
Although the Corps initially construed the Act to cover only
waters navigable-in-fact, the Corps and the EPA have since
issued nearly identical regulations expanding the definition of
“waters of the United States” to include some intrastate water-
bodies that are not navigable in the traditional sense.4
  3
     The CWA explicitly authorizes the Administrator of the EPA “to pre-
scribe such regulations as are necessary to carry out his functions under
this chapter.” 33 U.S.C. § 1361(a).
   4
     For present purposes, the two agencies’ regulatory definitions of “wa-
ters of the United States” are substantively identical.
2674 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
   [3] As relevant here, current regulations protect not only
navigable-in-fact waters but also tributaries of such waters, 40
C.F.R. § 122.2 (“Waters” (e)),5 non-navigable waterbodies
whose use or misuse could affect interstate commerce, id.
§ 122.2 (“Waters” (c)), and, most important for our purposes,
“ ‘wetlands’ adjacent to waters (other than waters that are
themselves wetlands)” otherwise covered by the Act, id.
§ 122.2 (“Waters” (g)). “Wetlands” are defined to mean

      areas that are inundated or saturated by surface or
      groundwater at a frequency and duration sufficient to
      support, and that under normal circumstances do
      support, a prevalence of vegetation typically adapted
      for life in saturated soil conditions. Wetlands gener-
      ally include swamps, marshes, bogs, and similar
      areas.

Id.

   [4] Under the controlling regulations, therefore, the only
areas that are defined as waters of the United States by reason
of adjacency to other such waters are “wetlands.” There is lit-
tle doubt that the regulatory definition is intended to be
exhaustive; the context makes that clear, as does the fact that
the definition states what “Waters of the United States . . .
means,” not what those waters “include.” See id.; Shell Oil
Co. v. EPA, 950 F.2d 741, 753 (D.C. Cir. 1992) (giving
restrictive effect to a definition that states what a term
“means” as opposed to what it “includes”). Disregarding the
unambiguous regulations limiting to wetlands the areas sub-
ject to the CWA because of adjacency, the district court deter-
mined that the Pond is covered by the Act because “the same
  5
    Section 122.2 of the regulations sets forth alphabetically the words or
terms being defined, and in some cases then provides letter-designated
subdivisions under a definition. For convenience, this opinion cites the
subdivisions under the definition of “Waters of the United States” as “Wa-
ters (a)” etc.
        SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2675
characteristics that justif[y] protection of adjacent wetlands
. . . apply as well to adjacent ponds.” This analysis was
improper.

   [5] When legislation implicitly grants to an agency the
authority to elucidate the meaning of a statutory provision, “a
court may not substitute its own construction of a statutory
provision for a reasonable interpretation made by the adminis-
trator of an agency.” Chevron, 467 U.S. at 844; see also
United States v. Mead Corp., 533 U.S. 218, 229 (2001);
Wash., Dep’t of Ecology v. U. S. EPA, 752 F.2d 1465, 1469
(9th Cir. 1985) (an agency’s reasonable interpretation of a
statute is entitled to deference “even if the agency could also
have reached another reasonable interpretation, or even if [the
court] would have reached a different result had [it] construed
the statute initially”). This principle applies with particular
force where, as here, “statutory construction involves recon-
ciling conflicting policies, and a full understanding of the
force of the statutory policy in the given situation (depends)
upon more than ordinary knowledge respecting the matters
subjected to agency regulations.” Wash., Dep’t of Ecology,
752 F.2d at 1469 (internal quotation marks and citations omit-
ted; parenthesis in original). The district court did not deter-
mine, nor was it argued, that the existing regulatory definition
of “waters of the United States” is unreasonable because it
fails to include all waterbodies, or some other subcategory of
waterbodies, adjacent to navigable waters. Moreover, for rea-
sons that will become apparent, it was not unreasonable for
the EPA to view wetlands as a special category subject to
CWA jurisdiction that otherwise would not extend beyond
navigable waters. We conclude, therefore, that the district
court erred when it found that the Pond is subject to CWA
jurisdiction solely because it is “adjacent”6 to Mowry Slough.
  6
    For present purposes, we accept Baykeeper’s definition of “adjacent”
as extending beyond physical proximity to include the additional factors
relied upon by the district court in determining that the Pond is adjacent
to the Slough (i.e., that the soils between the Pond and the Slough are satu-
rated, and that liquid has intermittently flowed from the Slough to the
Pond).
2676 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
   It is true that, in certain kinds of cases, there is a tension
between the purpose of authorized citizen suits and Chevron
deference. The purpose of the citizen suit provision of the
CWA, 33 U.S.C. § 1365, is to permit citizens to enforce the
Clean Water Act when the responsible agencies fail or refuse
to do so. For that reason, the CWA provides that a citizen
must give sixty days notice to the relevant agency prior to
commencing a citizen suit, and cannot bring such an action if
the agency is prosecuting an enforcement action. See id.
§ 1365(b)(1). In most cases, citizen suits are brought to
enforce limitations included in a permit issued by the EPA,
see, e.g., Sierra Club, Lone Star Chapter v. Cedar Point Oil
Co., 73 F.3d 546, 566 (5th Cir. 1996), and the suit does not
call into question any interpretation of the statute by the
agency. On occasion, however, a citizen sues because of a
discharge that the EPA has elected not to regulate. If the deci-
sion of the EPA is given conclusive deference, the citizen suit
would be defeated. Suit is therefore allowed despite the
EPA’s inaction, and a court may decide whether the offending
substance is a pollutant even when the EPA has not decided
that question. See id. at 566-67. Thus, we have held that a
court may, in entertaining a citizen suit, decide whether a dis-
charge of particular matter into navigable waters violates the
CWA even though the regulating agency determined that the
discharge was not subject to the requirement of a permit.
Ass’n to Protect Hammersley, Eld, and Totten Inlets v. Taylor
Resources, Inc., 299 F.3d 1007, 1012-13 (9th Cir. 2002).

   These cases do not, however, justify courts in denying def-
erence to the EPA or the Corps when, by formal regulation,
those agencies construe the meaning of a statutory term that
establishes the reach of the CWA that they administer. Cf.
Mead Corp., 533 U.S. at 230 (stating that the “overwhelming
number of our cases applying Chevron deference have
reviewed the fruits of notice-and-comment rulemaking or for-
mal adjudication”). Indeed, in deciding the merits of the citi-
zens’ claim in Taylor Resources, we were heavily guided by
the EPA’s definition of “point sources” in order not to “under-
      SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2677
mine the agency’s interpretation of the Clean Water Act.”
Taylor Resources, 299 F.3d at 1019. To decide the present
case brought by Baykeeper, the district court and we are
required to determine whether Cargill has discharged pollu-
tants into a water of the United States without a permit. For
reasons already stated, it is most appropriate to defer to the
administering agencies in construing the statutory term “wa-
ters of the United States,” which establishes the reach of the
CWA. Deference is especially suitable because this borderline
determination of non-navigable areas to be made subject to
the CWA is one that involves “conflicting policies” and
expert factual considerations for which the agencies are espe-
cially well suited. See Wash., Dep’t of Ecology, 752 F.2d at
1469. Because we do not want to undermine or throw into
chaos the EPA’s and the Corps’ construction of the statute
that establishes the reach of the CWA, Chevron deference is
required, even in this citizen suit.

   Baykeeper appears to concede that the regulatory definition
of “waters of the United States” does not support the district
court’s expansive construction. Nevertheless, it argues that
summary judgment was appropriately granted because “the
Supreme Court has repeatedly held that the CWA protects all
waterbodies with a ‘significant nexus’ to navigable waters.”
This is simply not the case. In United States v. Riverside Bay-
view Homes, Inc., 474 U.S. 121 (1985), the Court held that
the Corps did not exceed its statutory authority when it
defined “waters of the United States” to include adjacent wet-
lands. Id. at 134-35. The Supreme Court’s opinion leaves lit-
tle doubt about two of its foundations: (1) that it is up to the
Corps to determine where “waters of the United States” end,
and (2) that the Corps’ regulation was reasonable in treating
adjacent wetlands as a unique category subject to the CWA
despite their non-navigability:

    The Corps has concluded that wetlands may affect
    the water quality of adjacent lakes, rivers, and
    streams even when the waters of those bodies do not
2678 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
    actually inundate the wetlands. For example, wet-
    lands that are not flooded by adjacent waters may
    still tend to drain into those waters. In such circum-
    stances, the Corps has concluded that wetlands may
    serve to filter and purify water draining into adjacent
    bodies of water and to slow the flow of surface run-
    off into lakes, rivers, and streams and thus prevent
    flooding and erosion . . . . In addition, adjacent wet-
    lands may “serve significant natural biological func-
    tions, including food chain production, general
    habitat, and nesting, spawning, rearing and resting
    sites for aquatic . . . species.” In short, the Corps has
    concluded that wetlands adjacent to lakes, rivers,
    streams, and other bodies of water may function as
    integral parts of the aquatic environment even when
    the moisture creating the wetlands does not find its
    source in the adjacent bodies of water. Again, we
    cannot say that the Corps’ judgment on these matters
    is unreasonable . . . .

Id. (internal citations omitted). It is simply not permissible to
conclude from this passage that a court is authorized to con-
clude, when the administering agencies have reasonably ruled
to the contrary, that other non-navigable bodies of water,
which are not wetlands, are waters of the United States
because they are adjacent to such waters.

   Sixteen years after Bayside, the Supreme Court in
SWANCC struck down the Migratory Bird Rule, noting that
isolated intrastate ponds, unlike wetlands, lack a significant
nexus to navigable waters. 531 U.S. at 167-68. SWANCC did
not hold, however, that the Corps would be required to regu-
late all non-navigable bodies of water with some nexus to
navigable waters, and it certainly did not hold that a court
would be free to impose such a regulatory requirement if the
administering agencies did not.

   [6] Baykeeper’s reliance on Rapanos v. United States, 126
S. Ct. 2208 (2006), is similarly misplaced. Rapanos, like Riv-
      SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2679
erside Bayview, concerned the scope of the Corps’ authority
to regulate adjacent wetlands. Justice Kennedy’s controlling
concurrence explained that only wetlands with a significant
nexus to a navigable-in-fact waterway are covered by the Act.
Id. at 2248 (Kennedy, J., concurring) (“Consistent with
SWANCC and Riverside Bayview and with the need to give
the term ‘navigable’ some meaning, the Corps’ jurisdiction
over wetlands depends upon the existence of a significant
nexus between the wetlands in question and navigable waters
in the traditional sense.”). No Justice, even in dictum,
addressed the question whether all waterbodies with a signifi-
cant nexus to navigable waters are covered by the Act.

   [7] We conclude, therefore, that nothing in Bayview,
SWANCC or Rapanos requires or supports the view that Car-
gill’s Pond is a water of the United States because it is adja-
cent to Mowry Slough. Baykeeper contends, however, that the
Pond is more than merely adjacent; it has a nexus to Mowry
Slough. It is not sufficient, however, for Baykeeper simply to
make its individual case; it must establish that it was unrea-
sonable for the EPA to confine to wetlands the CWA’s reach
to non-navigable waterbodies adjacent to protected waters.
Even on its own terms, however, Baykeeper’s argument fails.
The evidence in support of Baykeeper’s nexus falls far short
of the nexus that Justice Kennedy required in Rapanos even
for wetlands that the Corps sought to hold subject to the
CWA:

    [W]etlands possess the requisite nexus, and thus
    come within the statutory phrase “navigable waters,”
    if the wetlands, either alone or in combination with
    similarly situated lands in the region, significantly
    affect the chemical, physical, and biological integrity
    of other covered waters more readily understood as
    “navigable.” When, in contrast, wetlands’ effects on
    water quality are speculative or insubstantial, they
    fall outside the zone fairly encompassed by the statu-
    tory term “navigable waters.”
2680 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
Rapanos, 126 S. Ct. at 2248 (Kennedy, J., concurring)
(emphasis added). By any permissible view of the evidence,
the effect of Cargill’s Pond on Mowry Slough is speculative
or insubstantial; the Pond does not significantly affect the
integrity of the Slough. First, there is no evidence that any
water has ever flowed from the Pond to the Slough. One
expert, asked whether “given the right hydrology conditions,”
water could flow from the Pond to the Slough, answered that
“it is possible.” There is no evidence, however, that those
“right hydrology conditions” have ever existed or were likely
to exist. This testimony fits the definition of “speculative.”
There was also much emphasis on the fact that, in some high
tide situations, water from the Slough has flowed over the
levee, or seeped through the levee, into the Pond. But flow in
that direction does not affect the navigable body of water in
the Slough. Thus the evidence does not meet Justice Kenne-
dy’s standard, and we emphasize that this standard was for
wetlands, for which the Corps had made special allowance
beyond the margins of the usual navigable waters at which the
CWA is aimed. We therefore reject the “adjacency-plus-
nexus” argument that Baykeeper puts forward.7

   Relying on Headwaters, Inc. v. Talent Irrigation District,
243 F.3d 526 (9th Cir. 2001), Baykeeper next argues that the
Pond is a “water[ ] of the United States” because even inter-
mittent hydrologic connections are sufficient to trigger CWA
jurisdiction. In Headwaters, we held that an irrigation canal
that drained intermittently into a protected waterbody was
subject to the CWA because it qualified as a “tributary” under
40 C.F.R. § 230.3(s)(5). Headwaters, 243 F.3d at 533. While
Headwaters is relevant to the permissible scope of the Corps’
  7
   It is important to keep in mind the key claim before us in this case: that
Cargill discharged pollutants into its Pond without a permit. There is no
question that, if Cargill engaged in some action that caused the discharge,
or permitted the leakage, of pollutants from the Pond into Mowry Slough
without a permit, it would be in violation of the CWA because of that dis-
charge into the Slough, which all parties agree is a water of the United
States. No such violation has been shown or is now claimed.
       SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2681
tributary jurisdiction, it has no bearing on the issue presented
here: whether the Pond is protected under the CWA because
it is adjacent to navigable waters. In any event, the instant
record does not support a finding that the Pond is a tributary
of the Slough; there is no evidence that water from the Pond
has ever flowed into the Slough or the Slough’s wetland.

   Our decisions in Baccarat Fremont Developers, LLC v.
United States, 425 F.3d 1150 (9th Cir. 2005), and Northern
California River Watch v. City of Healdsburg, 457 F.3d 1023
(9th Cir. 2006), also do not support Baykeeper’s position that
CWA jurisdiction extends to all adjacent waterbodies. In Bac-
carat, we held simply that SWANCC did not modify the
Supreme Court’s holding in Riverside Bayview that the Corps
can appropriately exercise jurisdiction over adjacent wetlands.
Baccarat, 425 F.3d at 1156-57. We expressed no opinion
regarding the Corps’ jurisdiction over adjacent waterbodies
not qualifying as wetlands.

   [8] City of Healdsburg also concerned the Corps’ jurisdic-
tion over adjacent wetlands. There, we applied Justice Kenne-
dy’s “significant nexus” standard, see Rapanos, 126 S. Ct. at
2248, and concluded that the wetland at issue was a “water[ ]
of the United States” because (among other reasons) its
waters seep directly into a protected river. City of Healdsburg,
457 F.3d at 1030-31. All told, we know of no case holding
that all waterbodies adjacent to navigable waters are covered
by the Act.

   As its fallback, Baykeeper argues that, under EPA regula-
tions, the Pond qualifies for CWA protection as a waterbody
whose use or misuse could affect interstate commerce, 40
C.F.R. § 122.2 (Waters (a), (c)), and as a “tributary” of a pro-
tected waterbody.8 Id. (Waters (e)). We note that neither of
  8
   These grounds for CWA coverage are also recognized in substantively
identical regulations issued by the Army Corps of Engineers. See 40
C.F.R. §§ 230.3(s)(1), (3), (5).
2682 SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION
these theories was urged as an independent ground of jurisdic-
tion in support of the most recent summary judgment, and
that, following that judgment, Baykeeper executed a settle-
ment agreement waiving the right to assert all jurisdictional
theories “other than the Adjacent Waters Theory upon which
the District Court based its Jurisdictional Ruling.” Baykeeper
apparently concedes that the waiver provision is valid and
enforceable.9 It argues, however, that its alternative theories
are not waived because the “Adjacent Waters Theory,”
broadly construed, includes consideration of facts other than
mere physical proximity.

  [9] Construing the waiver provision liberally in
Baykeeper’s favor, we conclude that Baykeeper reserved (at
most) the right to assert theories of CWA coverage that are
supported by facts on which the district court based its ruling.
Although the district court noted that the soils between the
Pond and the Slough are saturated, and that liquid from the
Slough has entered the Pond at high tide, it did not point to
any evidence, and we have found none, that liquid or matter
  9
    Some confusion has been caused by the fact that we and the parties
have from time to time referred to the issue in this case as whether the
Pond is within the “jurisdiction” of the CWA. A better statement of the
issue would be whether the Pond is within the coverage of the CWA. In
any event, the “jurisdiction” of the CWA has nothing to do with the juris-
diction of this court. Baykeeper’s complaint alleged that Cargill had vio-
lated the CWA by discharging pollutants into the waters of the United
States. That colorable allegation clearly gave the district court jurisdiction
over the case, see 33 U.S.C. § 1365(a), 28 U.S.C. § 1331, and we have
jurisdiction over this appeal pursuant to 28 U.S.C. § 1291. Baykeeper’s
failure to establish that Cargill’s Pond was a water of the United States is
a failure to make out a case, not a failure to establish the jurisdiction of
the court. See Arbaugh v. Y & H Corp., 126 S. Ct. 1235, 1242-45 (2006)
(discussing loose use of term “jurisdiction” and holding that failure to
establish that defendant is covered by the governing statute is failure to
make out a claim, not a failure to establish jurisdiction). Thus,
Baykeeper’s stipulation is not subject to question as an attempt to limit the
scope of our subject-matter jurisdiction. See id. at 1244 (“[S]ubject-matter
jurisdiction, because it involves the court’s power to hear a case, can never
be forfeited or waived.”) (internal quotation marks omitted).
      SAN FRANCISCO BAYKEEPER v. CARGILL SALT DIVISION 2683
from the Pond has flowed or will flow to the Slough or its
wetlands (a factual predicate for tributary jurisdiction). Nor
did the district court base its ruling on the fact that Cargill’s
discharge of pollutants into the Pond “could affect interstate
or foreign commerce.” In short, the “Adjacent Waters Theory
upon which the District Court based its Jurisdictional Ruling”
does not rely on evidence of tributary status or effect on inter-
state commerce. Accordingly, we conclude that these alterna-
tive theories are independent of the “Adjacent Waters
Theory” and are waived.

                          Conclusion

  For the foregoing reasons, the district court’s summary
judgment ruling is REVERSED. In light of that ruling,
Baykeeper’s cross-appeal is DISMISSED as moot.

  No. 04-17554: REVERSED.

  No. 05-15051: DISMISSED as moot.
