OPINION OF SCALIA, J. RAPANOS V. UNITED STATES 547 U. S. ____ (2006) SUPREME COURT OF THE UNITED STATES NOS. 04-1034 AND 04-1384 JOHN A. RAPANOS, et ux., et al.,
PETITIONERS

															04–1034 v. UNITED STATES JUNE CARABELL et al., PETITIONERS

															04–1384 v. UNITED STATES ARMY CORPS OF ENGINEERS
et al. on writs of certiorari to the united states
court of appeals for the sixth circuit [June 19, 2006] Justice Scalia announced
the judgment of the Court, and delivered an opinion, in which The
Chief Justice, Justice Thomas, and Justice Alito join.

															   In April 1989, petitioner John A.
Rapanos backfilled wetlands on a parcel of land in Michigan that he
owned and sought to develop. This parcel included 54 acres of land
with sometimes-saturated soil conditions. The nearest body of
navigable water was 11 to 20 miles away. 339 F. 3d 447, 449
(CA6 2003) (Rapanos I) . Regulators had informed Mr.
Rapanos that his saturated fields were “waters of the United
States,” 33 U. S. C. §1362(7), that could not be filled
without a permit. Twelve years of criminal and civil litigation
ensued.

															   The burden of federal regulation on those who
would deposit fill material in locations denominated “waters of the
United States” is not trivial. In deciding whether to grant or deny
a permit, the U. S. Army Corps of Engineers (Corps) exercises the
discretion of an enlightened despot, relying on such factors as
“economics,” “aesthetics,” “recreation,” and “in general, the needs
and welfare of the people,” 33 CFR §320.4(a) (2004).[ Footnote 1 ] The average applicant for an
individual permit spends 788 days and $271,596 in completing the
process, and the average applicant for a nationwide permit spends
313 days and $28,915—not counting costs of mitigation or design
changes. Sunding & Zilberman, The Economics of Environmental
Regulation by Licensing: An Assessment of Recent Changes to the
Wetland Permitting Process, 42 Natural Resources J. 59, 74–76
(2002). “[O]ver $1.7 billion is spent each year by the private and
public sectors obtaining wetlands permits.” Id. , at 81.
These costs cannot be avoided, because the Clean Water Act
“impose[s] criminal liability,” as well as steep civil fines, “on a
broad range of ordinary industrial and commercial activities.” Hanousek v. United States , 528 U. S. 1102 , 1103
(2000) (Thomas, J., dissenting from denial of certiorari). In this
litigation, for example, for backfilling his own wet fields, Mr.
Rapanos faced 63 months in prison and hundreds of thousands of
dollars in criminal and civil fines. See United States v. Rapanos, 235 F. 3d 256, 260 (CA6 2000).

															   The enforcement proceedings against Mr.
Rapanos are a small part of the immense expansion of federal
regulation of land use that has occurred under the Clean Water
Act—without any change in the governing statute—during the past
five Presidential administrations. In the last three decades, the
Corps and the Environmental Protection Agency (EPA) have
interpreted their jurisdiction over “the waters of the United
States” to cover 270-to-300 million acres of swampy lands in the
United States—including half of Alaska and an area the size of
California in the lower 48 States. And that was just the beginning.
The Corps has also asserted jurisdiction over virtually any parcel
of land containing a channel or conduit—whether man-made or
natural, broad or narrow, permanent or ephemeral—through which
rainwater or drainage may occasionally or intermittently flow. On
this view, the federally regulated “waters of the United States”
include storm drains, roadside ditches, ripples of sand in the
desert that may contain water once a year, and lands that are
covered by floodwaters once every 100 years. Because they include
the land containing storm sewers and desert washes, the statutory
“waters of the United States” engulf entire cities and immense arid
wastelands. In fact, the entire land area of the United States lies
in some drainage basin, and an endless network of visible channels
furrows the entire surface, containing water ephemerally wherever
the rain falls. Any plot of land containing such a channel may
potentially be regulated as a “water of the United States.”

															I

															   Congress passed the Clean Water
Act (CWA or Act) in 1972. The Act’s stated objective is “to restore
and maintain the chemical, physical, and biological integrity of
the Nation’s waters.” 86 Stat. 816, 33 U. S. C. §1251(a). The
Act also states that “[i]t is the policy of Congress to recognize,
preserve, and protect the primary responsibilities and rights of
States to prevent, reduce, and eliminate pollution, to plan the
development and use (including restoration, preservation, and
enhancement) of land and water resources, and to consult with the
Administrator in the exercise of his authority under this chapter.”
§1251(b).

															   One of the statute’s principal
provisions is 33 U. S. C. §1311(a), which provides that “the
discharge of any pollutant by any person shall be unlawful.” “The
discharge of a pollutant” is defined broadly to include “any
addition of any pollutant to navigable waters from any point
source,” §1362(12), and “pollutant” is defined broadly to include
not only traditional contaminants but also solids such as “dredged
spoil, . . . rock, sand, [and] cellar dirt,” §1362(6). And,
most relevant here, the CWA defines “navigable waters” as “the
waters of the United States, including the territorial seas.”
§1362(7).

															   The Act also provides certain exceptions to
its prohibition of “the discharge of any pollutant by any person.”
§1311(a). Section 1342(a) authorizes the Administrator of the EPA
to “issue a permit for the discharge of any pollutant, …
notwithstanding section 1311(a) of this title.” Section 1344
authorizes the Secretary of the Army, acting through the Corps, to
“issue permits … for the discharge of dredged or fill material into
the navigable waters at specified disposal sites.” §1344(a), (d).
It is the discharge of “dredged or fill material”—which, unlike
traditional water pollutants, are solids that do not readily wash
downstream—that we consider today.

															   For a century prior to the CWA, we had
interpreted the phrase “navigable waters of the United States” in
the Act’s predecessor statutes to refer to interstate waters that
are “navigable in fact” or readily susceptible of being rendered
so. The Daniel Ball , 10 Wall. 557, 563 (1871); see also United States v. Appalachian Elec. Power Co. , 311 U. S. 377 ,
406 (1940). After passage of the CWA, the Corps initially adopted
this traditional judicial definition for the Act’s term “navigable
waters.” See 39 Fed. Reg. 12119, codified at 33 CFR §209.120(d)(1)
(1974); see also Solid Waste Agency of Northern Cook Cty. v. Army Corps of Engineers , 531 U. S. 159 , 168 (2001) (SWANCC). After a District Court enjoined these
regulations as too narrow, Natural Resources Defense Council,
Inc. v. Callaway , 392 F. Supp. 685, 686 (DC
1975), the Corps adopted a far broader definition. See 40 Fed. Reg.
31324–31325 (1975); 42 Fed. Reg. 37144 (1977). The Corps’ new
regulations deliberately sought to extend the definition of “the
waters of the United States” to the outer limits of Congress’s
commerce power. See id., at 37144, n. 2.

															   The Corps’ current regulations interpret “the
waters of the United States” to include, in addition to traditional
interstate navigable waters, 33 CFR §328.3(a)(1) (2004), “[a]ll
interstate waters including interstate wetlands,” §328.3(a)(2);
“[a]ll other waters such as intrastate lakes, rivers, streams
(including intermittent streams), mudflats, sandflats, wetlands,
sloughs, prairie potholes, wet meadows, playa lakes, or natural
ponds, the use, degradation or destruction of which could affect
interstate or foreign commerce,” §328.3(a)(3); “[t]ributaries of
[such] waters,” §328.3(a)(5); and “[w]etlands adjacent to [such]
waters [and tributaries] (other than waters that are themselves
wetlands),” §328.3(a)(7). The regulation defines “adjacent”
wetlands as those “bordering, contiguous [to], or neighboring”
waters of the United States. §328.3(c). It specifically provides
that “[w]etlands separated from other waters of the United States
by man-made dikes or barriers, natural river berms, beach dunes and
the like are ‘adjacent wetlands.’ ” Ibid. We first addressed the proper interpretation
of 33 U. S. C. §1362(7)’s phrase “the waters of the United
States” in United States v. Riverside Bayview Homes,
Inc. , 474 U. S.
121 (1985). That case concerned a wetland that “was adjacent to
a body of navigable water,” because “the area characterized by
saturated soil conditions and wetland vegetation extended beyond
the boundary of respondent’s property to … a navigable waterway.” Id. , at 131; see also 33 CFR §328.3(b) (2004). Noting that
“the transition from water to solid ground is not necessarily or
even typically an abrupt one,” and that “the Corps must necessarily
choose some point at which water ends and land begins,” 474 U. S.,
at 132, we upheld the Corps’ interpretation of “the waters of the
United States” to include wetlands that “actually abut[ted] on”
traditional navigable waters. Id., at 135.

															   Following our decision in Riverside
Bayview , the Corps adopted increasingly broad interpretations
of its own regulations under the Act. For example, in 1986, to
“clarify” the reach of its jurisdiction, the Corps announced the
so-called “Migratory Bird Rule,” which purported to extend its
jurisdiction to any intrastate waters “[w]hich are or would be used
as habitat” by migratory birds. 51 Fed. Reg. 41217; see also SWANCC , supra, at 163–164. In addition, the Corps
interpreted its own regulations to include “ephemeral streams” and
“drainage ditches” as “tributaries” that are part of the “waters of
the United States,” see 33 CFR §328.3(a)(5), provided that they
have a perceptible “ordinary high water mark” as defined in
§328.3(e). 65 Fed. Reg. 12823 (2000). This interpretation extended
“the waters of the United States” to virtually any land feature
over which rainwater or drainage passes and leaves a visible
mark—even if only “the presence of litter and debris.” 33 CFR
§328.3(e). See also U. S. General Accounting Office, Report to the
Chairman, Subcommittee on Energy Policy, Natural Resources and
Regulating Affairs, Committee on Government Reform, House of
Representatives, Waters and Wetlands: Corps of Engineers Needs to
Evaluate Its District Office Practices in Determining Juris-
diction, GAO–04–297, pp. 20–22 (Feb. 2004) (hereinafter GAO
Report), http://www.gao.gov/new.items/d04297.pdf (all Internet
materials as visited June 9, 2006, and available in Clerk of
Court’s case file). Prior to our decision in SWANCC , lower
courts upheld the application of this expansive definition of
“tributaries” to such entities as storm sewers that contained flow
to covered waters during heavy rainfall, United States v. Eidson , 108 F. 3d 1336, 1340–1342 (CA11 1997), and
dry arroyos connected to remote waters through the flow of
groundwater over “centuries,” Quivira Mining Co. v. EPA , 765 F. 2d 126, 129 (CA10 1985).

															   In SWANCC , we considered the
application of the Corps’ “Migratory Bird Rule” to “an abandoned
sand and gravel pit in northern Illinois.” 531 U. S., at 162.
Observing that “[i]t was the significant nexus between the
wetlands and ‘navigable waters’ that informed our reading of the
CWA in Riverside Bayview ,” id., at 167 (emphasis
added), we held that Riverside Bayview did not establish
“that the jurisdiction of the Corps extends to ponds that are not
adjacent to open water.” 531 U. S., at 168 (emphasis deleted). On
the contrary, we held that “nonnavigable, isolated, intrastate
waters,” id. , at 171—which, unlike the wetlands at issue
in Riverside Bayview , did not “actually abu[t] on a
navigable waterway,” 531 U. S., at 167—were not included as “waters
of the United States.”

															   Following our decision in SWANCC , the
Corps did not significantly revise its theory of federal
jurisdiction under §1344(a). The Corps provided notice of a
proposed rulemaking in light of SWANCC , 68 Fed. Reg. 1991
(2003), but ultimately did not amend its published regulations.
Because SWANCC did not directly address tributaries, the
Corps notified its field staff that they “should continue to assert
jurisdiction over traditional navigable waters … and, generally
speaking, their tributary systems (and adjacent wetlands).” 68 Fed.
Reg. 1998. In addition, because SWANCC did not overrule Riverside Bayview , the Corps continues to assert
jurisdiction over waters “ ‘neighboring’ ” traditional
navigable waters and their tributaries. 68 Fed. Reg. 1997 (quoting
33 CFR §328.3(c) (2003)).

															   Even after SWANCC , the lower courts
have continued to uphold the Corps’ sweeping assertions of
jurisdiction over ephemeral channels and drains as “tributaries.”
For example, courts have held that jurisdictional “tributaries”
include the “intermittent flow of surface water through
approximately 2.4 miles of natural streams and manmade ditches
(paralleling and crossing under I–64),” Treacy v. Newdunn Assoc. , 344 F. 3d 407, 410 (CA4 2003); a
“roadside ditch” whose water took “a winding, thirty-two-mile path
to the Chesapeake Bay,” United States v. Deaton ,
332 F. 3d 698, 702 (CA4 2003); irrigation ditches and drains
that intermittently connect to covered waters, Community Assn.
for Restoration of Environment v. Henry Bosma Dairy ,
305 F. 3d 943, 954–955 (CA9 2002); Headwaters, Inc. v. Talent Irrigation Dist. , 243 F. 3d 526, 534 (CA9
2001); and (most implausibly of all) the “washes and arroyos” of an
“arid development site,” located in the middle of the desert,
through which “water courses . . . during periods of heavy
rain,” Save Our Sonoran, Inc. v. Flowers , 408
F. 3d 1113, 1118 (CA9 2005).[ Footnote 2 ]

															   These judicial constructions of “tributaries”
are not outliers. Rather, they reflect the breadth of the Corps’
determinations in the field. The Corps’ enforcement practices vary
somewhat from district to district because “the definitions used to
make jurisdictional determinations” are deliberately left “vague.”
GAO Report 26; see also id. , at 22. But district offices
of the Corps have treated, as “waters of the United States,” such
typically dry land features as “arroyos, coulees, and washes,” as
well as other “channels that might have little water flow in a
given year.” Id., at 20–21. They have also applied that
definition to such manmade, intermittently flowing features as
“drain tiles, storm drains systems, and culverts.” Id., at
24 (footnote omitted).

															   In addition to “tributaries,” the Corps and
the lower courts have also continued to define “adjacent” wetlands
broadly after SWANCC . For example, some of the Corps’
district offices have concluded that wetlands are “adjacent” to
covered waters if they are hydrologically connected “through
directional sheet flow during storm events,” GAO Report 18, or if
they lie within the “100-year floodplain” of a body of water—that
is, they are connected to the navigable water by flooding, on
average, once every 100 years, id., at 17, and n. 16.
Others have concluded that presence within 200 feet of a tributary
automatically renders a wetland “adjacent” and jurisdictional. Id., at 19. And the Corps has successfully defended such
theories of “adjacency” in the courts, even after SWANCC ’s
excision of “isolated” waters and wetlands from the Act’s coverage.
One court has held since SWANCC that wetlands separated
from flood control channels by 70-foot-wide berms, atop which ran
maintenance roads, had a “significant nexus” to covered waters
because, inter alia , they lay “within the 100 year
floodplain of tidal waters.” Baccarat Fremont Developers,
LLC v. Army Corps of Engineers , 425 F. 3d 1150, 1152,
1157 (CA9 2005). In one of the cases before us today, the Sixth
Circuit held, in agreement with “[t]he majority of courts,” that
“while a hydrological connection between the non-navigable and
navigable waters is required, there is no ‘direct abutment’
requirement” under SWANCC for “ ‘adjacency.’ ”
376 F. 3d 629, 639 (2004) (Rapanos II) . And even the
most insubstantial hydrologic connection may be held to constitute
a “significant nexus.” One court distinguished SWANCC on
the ground that “a molecule of water residing in one of these pits
or ponds [in SWANCC ] could not mix with molecules from
other bodies of water”—whereas, in the case before it, “water
molecules currently present in the wetlands will inevitably flow
towards and mix with water from connecting bodies,” and “[a] drop
of rainwater landing in the Site is certain to intermingle with
water from the [nearby river].” United States v. Rueth
Development Co. , 189 F. Supp. 2d 874, 877–878 (ND Ind.
2002).

															II

															   In these consolidated cases, we
consider whether four Michigan wetlands, which lie near ditches or
man-made drains that eventually empty into traditional navigable
waters, constitute “waters of the United States” within the meaning
of the Act. Petitioners in No. 04–1034, the Rapanos and their
affiliated businesses, deposited fill material without a permit
into wetlands on three sites near Midland, Michigan: the “Salzburg
site,” the “Hines Road site,” and the “Pine River site.” The
wetlands at the Salzburg site are connected to a man-made drain,
which drains into Hoppler Creek, which flows into the Kawkawlin
River, which empties into Saginaw Bay and Lake Huron. See Brief for
United States in No. 04–1034, p. 11; 339 F. 3d, at 449.
The wetlands at the Hines Road site are connected to something
called the “Rose Drain,” which has a surface connection to the
Tittabawassee River. App. to Pet. for Cert. in No. 04–1034, pp.
A23, B20. And the wetlands at the Pine River site have a surface
connection to the Pine River, which flows into Lake Huron. Id. , at A23–A24, B26. It is not clear whether the
connections between these wetlands and the nearby drains and
ditches are continuous or intermittent, or whether the nearby
drains and ditches contain continuous or merely occasional flows of
water.

															   The United States brought civil
enforcement proceedings against the Rapanos petitioners. The
District Court found that the three described wetlands were “within
federal jurisdiction” because they were “adjacent to other waters
of the United States,” and held petitioners liable for violations
of the CWA at those sites. Id., at B32–B35. On appeal, the
United States Court of Appeals for the Sixth Circuit affirmed,
holding that there was federal jurisdiction over the wetlands at
all three sites because “there were hydrological connections
between all three sites and corresponding adjacent tributaries of
navigable waters.” 376 F. 3d, at 643.

															   Petitioners in No. 04–1384, the Carabells,
were denied a permit to deposit fill material in a wetland located
on a triangular parcel of land about one mile from Lake St. Clair.
A man-made drainage ditch runs along one side of the wetland,
separated from it by a 4-foot-wide man-made berm. The berm is
largely or entirely impermeable to water and blocks drainage from
the wetland, though it may permit occasional overflow to the ditch.
The ditch empties into another ditch or a drain, which connects to
Auvase Creek, which empties into Lake St. Clair. See App. to Pet.
for Cert. in No. 04–1384, pp. 2a–3a.

															   After exhausting administrative appeals, the
Carabell petitioners filed suit in the District Court, challenging
the exercise of federal regulatory jurisdiction over their site.
The District Court ruled that there was federal jurisdiction
because the wetland “is adjacent to neighboring tributaries of
navigable waters and has a significant nexus to ‘waters of the
United States.’ ” Id. , at 49a. Again the Sixth
Circuit affirmed, holding that the Carabell wetland was “adjacent”
to navigable waters. 391 F. 3d 704, 708 (2004) (Carabell). We granted certiorari and consolidated the
cases, 546 U. S. ___ (2005), to decide whether these wetlands
constitute “waters of the United States” under the Act, and if so,
whether the Act is constitutional.

															III

															   The Rapanos petitioners contend
that the terms “navigable waters” and “waters of the United States”
in the Act must be limited to the traditional definition of The
Daniel Ball , which required that the “waters” be navigable in
fact, or susceptible of being rendered so. See 10 Wall., at 563.
But this definition cannot be applied wholesale to the CWA. The Act
uses the phrase “navigable waters” as a defined term, and
the definition is simply “the waters of the United States.” 33 U.
S. C. §1362(7). Moreover, the Act provides, in certain
circumstances, for the substitution of state for federal
jurisdiction over “navigable waters … other than those
waters which are presently used, or are susceptible to use in their
natural condition or by reasonable improvement as a means to
transport interstate or foreign commerce … including wetlands
adjacent thereto.” §1344(g)(1) (emphasis added). This provision
shows that the Act’s term “navigable waters” includes something
more than traditional navigable waters. We have twice stated that
the meaning of “navigable waters” in the Act is broader than the
traditional understanding of that term, SWANCC , 531 U. S.,
at 167; Riverside Bayview , 474 U. S., at 133.[ Footnote 3 ] We have also emphasized,
however, that the qualifier “navigable” is not devoid of
significance, SWANCC , supra, at 172.

															   We need not decide the precise
extent to which the qualifiers “navigable” and “of the United
States” restrict the coverage of the Act. Whatever the scope of
these qualifiers, the CWA authorizes federal jurisdiction only over
“waters.” 33 U. S. C. §1362(7). The only natural definition of
the term “waters,” our prior and subsequent judicial constructions
of it, clear evidence from other provisions of the statute, and
this Court’s canons of construction all confirm that “the waters of
the United States” in §1362(7) cannot bear the expansive meaning
that the Corps would give it.

															   The Corps’ expansive approach might be
arguable if the CSA defined “navigable waters” as “water of the
United States.” But “the waters of the United States” is something
else. The use of the definite article (“the”) and the plural number
(“waters”) show plainly that §1362(7) does not refer to water in
general. In this form, “the waters” refers more narrowly to water
“[a]s found in streams and bodies forming geographical features
such as oceans, rivers, [and] lakes,” or “the flowing or moving
masses, as of waves or floods, making up such streams or bodies.”
Webster’s New International Dictionary 2882 (2d ed. 1954)
(hereinafter Webster’s Second).[ Footnote 4 ] On this definition, “the waters of the United
States” include only relatively permanent, standing or flowing
bodies of water.[ Footnote 5 ]
The definition refers to water as found in “streams,” “oceans,”
“rivers,” “lakes,” and “bodies” of water “forming geographical
features.” Ibid. All of these terms connote continuously
present, fixed bodies of water, as opposed to ordinarily dry
channels through which water occasionally or intermittently flows.
Even the least substantial of the definition’s terms, namely
“streams,” connotes a continuous flow of water in a permanent
channel—especially when used in company with other terms such as
“rivers,” “lakes,” and “oceans.”[ Footnote 6 ] None of these terms encompasses transitory
puddles or ephemeral flows of water.

															   The restriction of “the waters of the United
States” to exclude channels containing merely intermittent or
ephemeral flow also accords with the commonsense understanding of
the term. In applying the definition to “ephemeral streams,” “wet
meadows,” storm sewers and culverts, “directional sheet flow during
storm events,” drain tiles, man-made drainage ditches, and dry
arroyos in the middle of the desert, the Corps has stretched the
term “waters of the United States” beyond parody. The plain
language of the statute simply does not authorize this “Land Is
Waters” approach to federal jurisdiction.

															   In addition, the Act’s use of the traditional
phrase “navigable waters” (the defined term) further confirms that
it confers jurisdiction only over relatively permanent bodies of water. The Act adopted that traditional term from its
predecessor statutes. See SWANCC , 531 U. S., at 180
(Stevens, J., dissenting). On the traditional understanding,
“navigable waters” included only discrete bodies of water.
For example, in The Daniel Ball , we used the terms
“waters” and “rivers” interchangeably. 10 Wall., at 563. And in Appalachian Electric , we consistently referred to the
“navigable waters” as “waterways.” 311 U. S., at 407–409. Plainly,
because such “waters” had to be navigable in fact or susceptible of
being rendered so, the term did not include ephemeral flows. As we
noted in SWANCC , the traditional term “navigable
waters”—even though defined as “the waters of the United
States”—carries some of its original substance: “[I]t is
one thing to give a word limited effect and quite another to give
it no effect whatever.” 531 U. S., at 172. That limited effect
includes, at bare minimum, the ordinary presence of water.

															   Our subsequent interpretation of the phrase
“the waters of the United States” in the CWA likewise confirms this
limitation of its scope. In Riverside Bayview , we stated
that the phrase in the Act referred primarily to “rivers, streams,
and other hydrographic features more conventionally
identifiable as ‘waters’ ” than the wetlands adjacent to
such features. 474 U. S., at 131 (emphasis added). We thus echoed
the dictionary definition of “waters” as referring to “streams and
bodies forming geographical features such as oceans,
rivers, [and] lakes.” Webster’s Second 2882 (emphasis added).
Though we upheld in that case the inclusion of wetlands abutting
such a “hydrographic featur[e]”—principally due to the difficulty
of drawing any clear boundary between the two, see 474 U. S., at
132; Part IV, infra —nowhere did we suggest that “the
waters of the United States” should be expanded to include, in
their own right, entities other than “hydrographic features more
conventionally identifiable as ‘waters.’ ” Likewise, in both Riverside Bayview and SWANCC , we repeatedly
described the “navigable waters” covered by the Act as “open water”
and “open waters.” See Riverside Bayview , supra, at 132, and n. 8, 134; SWANCC , supra, at
167, 172. Under no rational interpretation are typically dry
channels described as “ open waters.”

															   Most significant of all, the CWA itself
categorizes the channels and conduits that typically carry
intermittent flows of water separately from “navigable waters,” by
including them in the definition of “ ‘point source.’ ”
The Act defines “ ‘point source’ ” as “any discernible,
confined and discrete conveyance, including but not limited to any
pipe, ditch, channel, tunnel, conduit, well, discrete fissure,
container, rolling stock, concentrated animal feeding operation, or
vessel or other floating craft, from which pollutants are or may be
discharged.” 33 U. S. C. §1362(14). It also defines
“ ‘discharge of a pollutant’ ” as “any addition of any
pollutant to navigable waters from any point
source.” §1362(12)(A) (emphases added). The definitions thus
conceive of “point sources” and “navigable waters” as separate and
distinct categories. The definition of “discharge” would make
little sense if the two categories were significantly overlapping.
The separate classification of “ditch[es], channel[s], and
conduit[s]”—which are terms ordinarily used to describe the
watercourses through which intermittent waters typically
flow—shows that these are, by and large, not “waters of
the United States.”[ Footnote
7 ]

															   Moreover, only the foregoing definition of
“waters” is consistent with the CWA’s stated “policy of Congress to
recognize, preserve, and protect the primary responsibilities and
rights of the States to prevent, reduce, and eliminate pollution,
[and] to plan the development and use (including restoration,
preservation, and enhancement) of land and water resources
… .” §1251(b). This statement of policy was included in the
Act as enacted in 1972, see 86 Stat. 816, prior to the addition of
the optional state administration program in the 1977 amendments,
see 91 Stat. 1601. Thus the policy plainly referred to something
beyond the subsequently added state administration program of 33 U.
S. C. §1344(g)–( l ). But the expansive theory advanced
by the Corps, rather than “preserv[ing] the primary rights and
responsibilities of the States,” would have brought virtually all
“plan[ning of] the development and use . . . of land and water
resources” by the States under federal control. It is therefore an
unlikely reading of the phrase “the waters of the United
States.”[ Footnote 8 ]

															   Even if the phrase “the waters of the United
States” were ambiguous as applied to intermittent flows, our own
canons of construction would establish that the Corps’
interpretation of the statute is impermissible. As we noted in SWANCC , the Government’s expansive interpretation would
“result in a significant impingement of the States’ traditional and
primary power over land and water use.” 531 U. S., at 174.
Regulation of land use, as through the issuance of the development
permits sought by petitioners in both of these cases, is a
quintessential state and local power. See FERC v. Mississippi , 456 U. S. 742 , 768, n.
30 (1982); Hess v. Port Authority Trans-Hudson
Corporation , 513
U. S. 30 , 44 (1994). The extensive federal jurisdiction urged
by the Government would authorize the Corps to function as a de
facto regulator of immense stretches of intrastate land—an
authority the agency has shown its willingness to exercise with the
scope of discretion that would befit a local zoning board. See 33
CFR §320.4(a)(1) (2004). We ordinarily expect a “clear and
manifest” statement from Congress to authorize an unprecedented
intrusion into traditional state authority. See BFP v. Resolution Trust Corporation , 511 U. S. 531 , 544
(1994). The phrase “the waters of the United States” hardly
qualifies.

															   Likewise, just as we noted in SWANCC ,
the Corps’ interpretation stretches the outer limits of Congress’s
commerce power and raises difficult questions about the ultimate
scope of that power. See 531 U. S., at 173. (In developing the
current regulations, the Corps consciously sought to extend its
authority to the farthest reaches of the commerce power. See 42
Fed. Reg. 37127 (1977).) Even if the term “the waters of the United
States” were ambiguous as applied to channels that sometimes host
ephemeral flows of water (which it is not), we would expect a
clearer statement from Congress to authorize an agency theory of
jurisdiction that presses the envelope of constitutional validity.
See Edward J. DeBartolo Corp. v. Florida Gulf Coast
Building & Constr. Trades Council , 485 U. S. 568 , 575
(1988).[ Footnote 9 ]

															   In sum, on its only plausible interpretation,
the phrase “the waters of the United States” includes only those
relatively permanent, standing or continuously flowing bodies of
water “forming geographic features” that are described in ordinary
parlance as “streams[,] … oceans, rivers, [and] lakes.” See
Webster’s Second 2882. The phrase does not include channels through
which water flows intermittently or ephemerally, or channels that
periodically provide drainage for rainfall. The Corps’ expansive
interpretation of the “the waters of the United States” is thus not
“based on a permissible construction of the statute.” Chevron
U. S. A. Inc. v. Natural Resources Defense
Council , Inc., 467 U. S. 837 , 843
(1984).

															IV

															   In Carabell , the Sixth
Circuit held that the nearby ditch constituted a “tributary” and
thus a “water of the United States” under 33 CFR §328.3(a)(5)
(2004). See 391 F. 3d, at 708–709. Likewise in Rapanos , the Sixth Circuit held that the nearby ditches
were “tributaries” under §328(a)(5). 376 F. 3d, at 643. But Rapanos II also stated that, even if the ditches were not
“waters of the United States,” the wetlands were “adjacent” to remote traditional navigable waters in virtue of the
wetlands’ “hydrological connection” to them. See id. , at
639–640. This statement reflects the practice of the Corps’
district offices, which may “assert jurisdiction over a wetland
without regulating the ditch connecting it to a water of the United
States.” GAO Report 23. We therefore address in this Part whether a
wetland may be considered “adjacent to” remote “waters of the
United States,” because of a mere hydrologic connection to
them.

															   In Riverside Bayview , we
noted the textual difficulty in including “wetlands” as a subset of
“waters”: “On a purely linguistic level, it may appear unreasonable
to classify ‘lands,’ wet or otherwise, as ‘waters.’ ” 474 U.
S., at 132. We acknowledged, however, that there was an inherent
ambiguity in drawing the boundaries of any “waters”:

															“[T]he Corps must necessarily choose some point at
which water ends and land begins. Our common experience tells us
that this is often no easy task: the transition from water to solid
ground is not necessarily or even typically an abrupt one. Rather,
between open waters and dry land may lie shallows, marshes,
mudflats, swamps, bogs—in short, a huge array of areas that are not
wholly aquatic but nevertheless fall far short of being dry land.
Where on this continuum to find the limit of ‘waters’ is far from
obvious.” Ibid. Because of this inherent
ambiguity, we deferred to the agency’s inclusion of wetlands
“actually abut[ting]” traditional navigable waters: “Faced with
such a problem of defining the bounds of its regulatory authority,”
we held, the agency could reasonably conclude that a wetland that
“adjoin[ed]” waters of the United States is itself a part of those
waters. Id., at 132, 135, and n. 9. The difficulty of
delineating the boundary between water and land was central to our
reasoning in the case: “In view of the breadth of federal
regulatory authority contemplated by the Act itself and the
inherent difficulties of defining precise bounds to regulable
waters , the Corps’ ecological judgment about the relationship
between waters and their adjacent wetlands provides an adequate
basis for a legal judgment that adjacent wetlands may be defined as
waters under the Act.” Id. , at 134 (emphasis
added).[ Footnote 10 ]

															   When we characterized the holding of Riverside Bayview in SWANCC , we referred to the
close connection between waters and the wetlands that they
gradually blend into: “It was the significant nexus between the wetlands and ‘navigable waters’ that informed our
reading of the CWA in Riverside Bayview Homes .” 531 U. S.,
at 167 (emphasis added). In particular, SWANCC rejected
the notion that the ecological considerations upon which the Corps
relied in Riverside Bayview —and upon which the dissent
repeatedly relies today, see post , at 10–11, 12, 13–14,
15, 18–19, 21–22, 24–25—provided an independent basis for
including entities like “wetlands” (or “ephemeral streams”) within
the phrase “the waters of the United States.” SWANCC found
such ecological considerations irrelevant to the question whether
physically isolated waters come within the Corps’ jurisdiction. It
thus confirmed that Riverside Bayview rested upon the
inherent ambiguity in defining where water ends and abutting
(“adjacent”) wetlands begin, permitting the Corps’ reliance on
ecological considerations only to resolve that ambiguity in favor of treating all abutting wetlands as waters. Isolated
ponds were not “waters of the United States” in their own right,
see 531 U. S., at 167, 171, and presented no boundary-drawing
problem that would have justified the invocation of ecological
factors to treat them as such.

															   Therefore, only those wetlands with a
continuous surface connection to bodies that are “waters of the
United States” in their own right, so that there is no clear
demarcation between “waters” and wetlands, are “adjacent to” such
waters and covered by the Act. Wetlands with only an intermittent,
physically remote hydrologic connection to “waters of the United
States” do not implicate the boundary-drawing problem of Riverside Bayview , and thus lack the necessary connection
to covered waters that we described as a “significant nexus” in SWANCC . 531 U. S., at 167. Thus, establishing that
wetlands such as those at the Rapanos and Carabell sites are
covered by the Act requires two findings: First, that the adjacent
channel contains a “wate[r] of the United States,” ( i.e., a relatively permanent body of water connected to traditional
interstate navigable waters); and second, that the wetland has a
continuous surface connection with that water, making it difficult
to determine where the “water” ends and the “wetland” begins.

															V

															   Respondents and their amici urge that such restrictions on the scope of
“navigable waters” will frustrate enforcement against traditional
water polluters under 33 U. S. C. §§1311 and 1342. Because the
same definition of “navigable waters” applies to the entire
statute, respondents contend that water polluters will be able to
evade the permitting requirement of §1342(a) simply by discharging
their pollutants into noncovered intermittent watercourses that lie
upstream of covered waters. See Tr. of Oral Arg. 74–75.

															   That is not so. Though we do not
decide this issue, there is no reason to suppose that our
construction today significantly affects the enforcement of §1342,
inasmuch as lower courts applying §1342 have not characterized
intermittent channels as “waters of the United States.” The Act
does not forbid the “addition of any pollutant directly to
navigable waters from any point source,” but rather the “addition
of any pollutant to navigable waters.” §1362(12)(A)
(emphasis added); §1311(a). Thus, from the time of the CWA’s
enactment, lower courts have held that the discharge into
intermittent channels of any pollutant that naturally washes
downstream likely violates §1311(a), even if the pollutants
discharged from a point source do not emit “directly into” covered
waters, but pass “through conveyances” in between. United
States v. Velsicol Chemical Corp. , 438 F. Supp.
945, 946–947 (WD Tenn. 1976) (a municipal sewer system separated
the “point source” and covered navigable waters). See also Sierra Club v. El Paso Gold Mines, Inc. , 421
F. 3d 1133, 1137, 1141 (CA10 2005) (2.5 miles of tunnel
separated the “point source” and “navigable waters”).

															   In fact, many courts have held that such
upstream, intermittently flowing channels themselves constitute
“point sources” under the Act. The definition of “point source”
includes “any pipe, ditch, channel, tunnel, conduit, well, discrete
fissure, container, rolling stock, concentrated animal feeding
operation, or vessel or other floating craft, from which pollutants
are or may be discharged.” 33 U. S. C. §1362(14). We have held
that the Act “makes plain that a point source need not be the
original source of the pollutant; it need only convey the pollutant
to ‘navigable waters.’ ” South Fla. Water Management
Dist. v. Miccosukee Tribe , 541 U. S. 95 , 105 (2004).
Cases holding the intervening channel to be a point source include United States v. Ortiz , 427 F. 3d 1278, 1281
(CA10 2005) (a storm drain that carried flushed chemicals from a
toilet to the Colorado River was a “point source”), and Dague v. Burlington , 935 F. 2d 1343,
1354–1355 (CA2 1991) (a culvert connecting two bodies of navigable
water was a “point source”), rev’d on other grounds, 505 U. S. 557 (1992).
Some courts have even adopted both the “indirect discharge”
rationale and the “point source” rationale in the alternative,
applied to the same facts. See, e.g. , Concerned Area
Residents for Environment v. Southview Farm , 34
F. 3d 114, 118–119 (CA2 1994). On either view, however, the
lower courts have seen no need to classify the intervening conduits
as “waters of the United States.”

															   In contrast to the pollutants normally covered
by the permitting requirement of §1342(a), “dredged or fill
material,” which is typically deposited for the sole purpose of
staying put, does not normally wash downstream,[ Footnote 11 ] and thus does not normally
constitute an “addition … to navigable waters” when deposited in
upstream isolated wetlands. §§1344(a), 1362(12). The Act recognizes
this distinction by providing a separate permitting program for
such discharges in §1344(a). It does not appear, therefore, that
the interpretation we adopt today significantly reduces the scope
of §1342 of the Act.

															   Respondents also urge that the narrower
interpretation of “waters” will impose a more difficult burden of
proof in enforcement proceedings under §§1311(a) and 1342(a), by
requiring the agency to demonstrate the downstream flow of the
pollutant along the intermittent channel to traditional “waters.”
See Tr. of Oral Arg. 57. But, as noted above, the lower courts do
not generally rely on characterization of intervening channels as
“waters of the United States” in applying §1311 to the traditional
pollutants subject to §1342. Moreover, the proof of downstream flow
of pollutants required under §1342 appears substantially similar,
if not identical, to the proof of a hydrologic connection that
would be required, on the Sixth Circuit’s theory of jurisdiction,
to prove that an upstream channel or wetland is a “wate[r] of the
United States.” See Rapanos II , 376 F. 3d, at 639.
Compare, e.g. , App. to Pet. for Cert. in No. 04–1034, at
B11, B20, B26 (testimony of hydrologic connections based on
observation of surface water connections), with Southview
Farm , supra, at 118–121 (testimony of discharges
based on observation of the flow of polluted water). In either
case, the agency must prove that the contaminant-laden waters
ultimately reach covered waters.

															   Finally, respondents and many amici admonish that narrowing the definition of “the waters of the United
States” will hamper federal efforts to preserve the Nation’s
wetlands. It is not clear that the state and local conservation
efforts that the CWA explicitly calls for, see 33 U. S. C.
§1251(b), are in any way inadequate for the goal of preservation.
In any event, a Comprehensive National Wetlands Protection Act is
not before us, and the “wis[dom]” of such a statute, post ,
at 19 (opinion of Stevens, J.), is beyond our ken. What is clear,
however, is that Congress did not enact one when it granted the
Corps jurisdiction over only “the waters of the United
States.”

															VI

															   In an opinion long on praise of
environmental protection and notably short on analysis of the
statutory text and structure, the dissent would hold that “the
waters of the United States” include any wetlands “adjacent” (no
matter how broadly defined) to “tributaries” (again, no matter how
broadly defined) of traditional navigable waters. For legal support
of its policy-laden conclusion, the dissent relies exclusively on
two sources: “[o]ur unanimous opinion in Riverside
Bayview ,” post , at 6; and “Congress’ deliberate
acquiescence in the Corps’ regulations in 1977,” post , at
11. Each of these is demonstrably inadequate to support the
apparently limitless scope that the dissent would permit the Corps
to give to the Act.

															A

															   The dissent’s assertion that Riverside Bayview “squarely controls these cases,” post , at 6, is wholly implausible. First, Riverside
Bayview could not possibly support the dissent’s acceptance of
the Corps’ inclusion of dry beds as “tributaries,” post ,
at 19, because the definition of tributaries was not at issue in
that case. Riverside Bayview addressed only the Act’s
inclusion of wetlands abutting navigable-in-fact waters, and said
nothing at all about what non-navigable tributaries the Act might
also cover. Riverside Bayview likewise provides no support for the dissent’s complacent
acceptance of the Corps’ definition of “adjacent,” which (as noted
above) has been extended beyond reason to include, inter
alia , the 100-year floodplain of covered waters. See supra , at 9. The dissent notes that Riverside
Bayview quoted without comment the Corps’ description of
“adjacent” wetlands as those “that form the border of or are in
reasonable proximity to other waters of the United States.” Post , at 8 (citing 474 U. S., at 134 (quoting 42 Fed. Reg.
37128)). As we have already discussed, this quotation provides no
support for the inclusion of physically unconnected wetlands as
covered “waters.” See supra , at 22–23, n. 10. The
dissent relies principally on a footnote in Riverside
Bayview recognizing that “ ‘not every adjacent wetland is
of great importance to the environment of adjoining bodies of
water,’ ” and that all “ ‘adjacent’ ” wetlands are
nevertheless covered by the Act, post , at 8 (quoting 474
U. S., at 135, n. 9). Of course, this footnote says nothing to support the dissent’s broad definition of
“adjacent”—quite the contrary, the quoted sentence uses “adjacent”
and “adjoining” interchangeably , and the footnote
qualifies a sentence holding that the wetland was covered
“ [b]ecause ” it “actually abut[ted] on a navigable
waterway.” Id. , at 135 (emphasis added). Moreover, that
footnote’s assertion that the Act may be interpreted to include
even those adjoining wetlands that are “lacking in importance to
the aquatic environment,” id. , at 135, n. 9, confirms
that the scope of ambiguity of “the waters of the United States” is
determined by a wetland’s physical connection to covered
waters, not its ecological relationship thereto.

															   The dissent reasons (1) that Riverside
Bayview held that “the waters of the United States” include
“adjacent wetlands,” and (2) we must defer to the Corps’
interpretation of the ambiguous word “adjacent.” Post , at
20–21. But this is mere legerdemain. The phrase “adjacent wetlands”
is not part of the statutory definition that the Corps is
authorized to interpret, which refers only to “the waters of the
United States,” 33 U. S. C. §1362(7).[ Footnote 12 ] In expounding the term “adjacent”
as used in Riverside Bayview , we are explaining our
own prior use of that word to interpret the definitional
phrase “the waters of the United States.” However ambiguous the
term may be in the abstract, as we have explained earlier,
“adjacent” as used in Riverside Bayview is not ambiguous
between “physically abutting” and merely “nearby.” See supra , at 21–23.

															   The dissent would distinguish SWANCC on the ground that it “had nothing to say about wetlands,” post , at 9— i.e., it concerned “isolated ponds ” rather than isolated wetlands . This is the
ultimate distinction without a difference. If isolated “permanent
and seasonal ponds of varying size … and depth,” 531 U. S., at
163—which, after all, might at least be described as “waters” in
their own right—did not constitute “waters of the United States,” a fortiori, isolated swampy lands do not
constitute “waters of the United States.” See also 474 U. S., at
132. As the author of today’s dissent has written, “[i]f, as I
believe, actually navigable waters lie at the very heart of
Congress’ commerce power and ‘isolated,’ nonnavigable waters lie
closer to … the margin, ‘isolated wetlands,’ which are themselves
only marginally ‘waters,’ are the most marginal category of ‘waters
of the United States’ potentially covered by the statute.” 531 U.
S., at 187, n. 13 (Stevens, J., dissenting).

															   The only other ground that the dissent offers
to distinguish SWANCC is that, unlike the ponds in SWANCC , the wetlands in these cases are “adjacent to
navigable bodies of water and their tributaries”—where “adjacent”
may be interpreted who-knows-how broadly. It is not clear why
roughly defined physical proximity should make such a
difference—without actual abutment, it raises no boundary-drawing
ambiguity, and it is undoubtedly a poor proxy for ecological
significance. In fact, though the dissent is careful to restrict
its discussion to wetlands “adjacent” to tributaries, its reasons for including those wetlands are strictly
ecological—such wetlands would be included because they “serve …
important water quality roles,” post , at 11, and “play
important roles in the watershed,” post , at 18–19. This
reasoning would swiftly overwhelm SWANCC altogether; after
all, the ponds at issue in SWANCC could, no less than the
wetlands in these cases, “offer ‘nesting, spawning, rearing and
resting sites for aquatic or land species,’ ” and
“ ‘serve as valuable storage areas for storm and flood
waters,’ ” post , at 9–10. The dissent’s exclusive
focus on ecological factors, combined with its total deference to
the Corps’ ecological judgments, would permit the Corps to regulate
the entire country as “waters of the United States.”

															B

															   Absent a plausible ground in our
case law for its sweeping position, the dissent relies heavily on
“Congress’ deliberate acquiescence in the Corps’ regulations in
1977,” post , at 11—noting that “[w]e found [this
acquiescence] significant in Riverside Bayview ,” and even
“acknowledged in SWANCC ” that we had done so, post , at 12. SWANCC “acknowledged” that Riverside Bayview had relied on congressional acquiescence
only to criticize that reliance. It reasserted in no uncertain
terms our oft-expressed skepticism towards reading the tea leaves
of congressional inaction:

															“Although we have recognized congressional
acquiescence to administrative interpretations of a statute in some
situations, we have done so with extreme care. Failed legislative
proposals are a particularly dangerous ground on which to rest an
interpretation of a prior statute. … The relationship between the
actions and inactions of the 95th Congress and the intent of the
92d Congress in passing [§1344(a)] is also considerably attenuated.
Because subsequent history is less illuminating than the
contemporaneous evidence, respondents face a difficult task in
overcoming the plain text and import of [§1344(a)].” 531 U. S., at
169 (citations, internal quotation marks, and footnote
omitted).

															   Congress takes no governmental
action except by legislation. What the dissent refers to as
“Congress’ deliberate acquiescence” should more appropriately be
called Congress’s failure to express any opinion. We have no idea
whether the Members’ failure to act in 1977 was attributable to
their belief that the Corps’ regulations were correct, or rather to
their belief that the courts would eliminate any excesses, or
indeed simply to their unwillingness to confront the environmental
lobby. To be sure, we have sometimes relied on congressional
acquiescence when there is evidence that Congress considered and
rejected the “ precise issue” presented before the Court, Bob Jones Univ. v. United States , 461 U. S. 574 , 600
(1983) (emphasis added). However, “[a]bsent such overwhelming
evidence of acquiescence, we are loath to replace the plain
text and original understanding of a statute with an amended agency
interpretation.” SWANCC , supra, at 169, n. 5
(emphasis added).

															   The dissent falls far short of producing
“overwhelming evidence” that Congress considered and failed to act
upon the “precise issue” before the Court today—namely, what
constitutes an “adjacent” wetland covered by the Act. Citing Riverside Bayview ’s account of the 1977 debates, the
dissent claims nothing more than that Congress “conducted extensive
debates about the Corps’ regulatory jurisdiction over wetlands
[and] rejected efforts to limit that jurisdiction … .” Post , at 11. In fact, even that vague description goes too
far. As recounted in Riverside Bayview , the 1977 debates
concerned a proposal to “limi[t] the Corps’ authority under [§1344]
to waters navigable in fact and their adjacent wetlands (defined as
wetlands periodically inundated by contiguous navigable waters),”
474 U. S., at 136. In rejecting this proposal, Congress merely
failed to enact a limitation of “waters” to include only
navigable-in-fact waters—an interpretation we affirmatively reject
today, see supra , at 12—and a definition of wetlands based
on “periodi[c] inundat[ion]” that appears almost nowhere in the
briefs or opinions of these cases.[ Footnote 13 ] No plausible interpretation of this
legislative inaction can construe it as an implied endorsement of
every jot and tittle of the Corps’ 1977 regulations. In fact, Riverside Bayview itself relied on this legislative
inaction only as “at least some evidence of the reasonableness” of
the agency’s inclusion of adjacent wetlands under the Act, 474 U.
S., at 137, and for the observation that “even those who would have
restricted the reach of the Corps’ jurisdiction” would not have
excised adjacent wetlands, ibid. Both of these conclusions
are perfectly consistent with our interpretation, and neither
illuminates the disputed question of what constitutes an “adjacent”
wetland.

															C

															   In a curious appeal to entrenched
Executive error, the dissent contends that “the appropriateness of
the Corps’ 30-year implementation of the Clean Water Act should be
addressed to Congress or the Corps rather than to the Judiciary.” Post, at 14; see also post , at 2, 22. Surely this
is a novel principle of administrative law—a sort of 30-year
adverse possession that insulates disregard of statutory text from
judicial review. It deservedly has no precedent in our
jurisprudence. We did not invoke such a principle in SWANCC , when we invalidated one aspect of the Corps’
implementation.

															   The dissent contends that
“[b]ecause there is ambiguity in the phrase ‘waters of the United
States’ and because interpreting it broadly to cover such ditches
and streams advances the purpose of the Act, the Corps’ approach
should command our deference.” Post, at 19. Two defects in
a single sentence: “[W]aters of the United States” is in some respects ambiguous. The scope of that
ambiguity, however, does not conceivably extend to whether storm
drains and dry ditches are “waters,” and hence does not support the
Corps’ interpretation. And as for advancing “the purpose of the
Act”: We have often criticized that last resort of extravagant
interpretation, noting that no law pursues its purpose at all
costs, and that the textual limitations upon a law’s scope are no
less a part of its “purpose” than its substantive authorizations.
See, e.g. , Director, Office of Workers’ Compensation
Programs v. Newport News Shipbuilding & Dry Dock
Co. , 514 U. S.
122 , 135–136 (1995).

															   Finally, we could not agree more with the
dissent’s statement, post, at 14, that “[w]hether the
benefits of particular conservation measures outweigh their costs
is a classic question of public policy that should not be answered
by appointed judges.” Neither, however, should it be answered by
appointed officers of the Corps of Engineers in contradiction of
congressional direction. It is the dissent’s opinion, and not ours,
which appeals not to a reasonable interpretation of enacted text,
but to the great environmental benefits that a patently
unreasonable interpretation can achieve. We have begun our
discussion by mentioning, to be sure, the high costs imposed by
that interpretation—but they are in no way the basis for our
decision, which rests, plainly and simply, upon the limited meaning
that can be borne by the phrase “waters of the United States.”

															VII

															   Justice Kennedy’s opinion
concludes that our reading of the Act “is inconsistent with its
text, structure, and purpose.” Post, at 19. His own
opinion, however, leaves the Act’s “text” and “structure” virtually
unaddressed, and rests its case upon an interpretation of the
phrase “significant nexus,” ibid. , which appears in one of
our opinions.

															   To begin with, Justice Kennedy’s
reading of “significant nexus” bears no easily recognizable
relation to either the case that used it (SWANCC) or to
the earlier case that that case purported to be interpreting (Riverside Bayview) . To establish a “significant nexus,”
Justice Kennedy would require the Corps to “establish … on a
case-by-case basis” that wetlands adjacent to nonnavigable
tributaries “significantly affect the chemical, physical, and
biological integrity of other covered waters more readily
understood as ‘navigable.’ ” Post , at 25, 23. This
standard certainly does not come from Riverside Bayview ,
which explicitly rejected such case-by-case determinations of
ecological significance for the jurisdictional question
whether a wetland is covered, holding instead that all physically connected wetlands are covered. 474 U. S., at 135,
n. 9. It is true enough that one reason for accepting that
physical-connection criterion was the likelihood that a physically
connected wetland would have an ecological effect upon the adjacent
waters. But case-by-case determination of ecological effect was
not the test . Likewise, that test cannot be derived from SWANCC ’s characterization of Riverside Bayview ,
which emphasized that the wetlands which possessed a “significant
nexus” in that earlier case “actually abutted on a navigable
waterway,” 531 U. S., at 167, and which specifically
rejected the argument that physically unconnected ponds could
be included based on their ecological connection to covered waters.
In fact, Justice Kennedy acknowledges that neither Riverside
Bayview nor SWANCC required, for wetlands abutting
navigable-in-fact waters, the case-by-case ecological determination
that he proposes for wetlands that neighbor nonnavigable
tributaries. See post , at 23. Thus, Justice Kennedy
misreads SWANCC’s “significant nexus” statement as
mischaracterizing Riverside Bayview to adopt a
case-by-case test of ecological significance; and then transfers
that standard to a context that Riverside Bayview expressly declined to address (namely, wetlands nearby
non-navigable tributaries); while all the time conceding that this standard does not apply in the context that Riverside
Bayview did address (wetlands abutting navigable
waterways). Truly, this is “turtles all the way down.”[ Footnote 14 ]

															   But misreading our prior decisions is not the
principal problem. The principal problem is reading them in utter
isolation from the text of the Act. One would think, after reading
Justice Kennedy’s exegesis, that the crucial provision of the text
of the CWA was a jurisdictional requirement of “significant nexus”
between wetlands and navigable waters. In fact, however, that
phrase appears nowhere in the Act, but is taken from SWANCC ’s cryptic characterization of the holding of Riverside Bayview . Our interpretation of the
phrase is both consistent with those opinions and compatible with what the Act does establish as the
jurisdictional criterion: “waters of the United States.” Wetlands
are “waters of the United States” if they bear the “significant
nexus” of physical connection, which makes them as a practical
matter indistinguishable from waters of the United States.
What other nexus could conceivably cause them to be “waters of the United States”? Justice Kennedy’s test
is that they, “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,’ ” post, at 23 (emphasis added). But what possible linguistic
usage would accept that whatever (alone or in combination) affects waters of the United States is waters of
the United States?

															   Only by ignoring the text of the statute and
by assuming that the phrase of SWANCC (“significant
nexus”) can properly be interpreted in isolation from that text
does Justice Kennedy reach the conclusion he has arrived at.
Instead of limiting its meaning by reference to the text it was
applying, he purports to do so by reference to what he calls the
“purpose” of the statute. Its purpose is to clean up the waters of
the United States, and therefore anything that might “significantly
affect” the purity of those waters bears a “significant nexus” to
those waters, and thus (he never says this, but the text of the
statute demands that he mean it) is those waters. This is
the familiar tactic of substituting the purpose of the statute for
its text, freeing the Court to write a different statute that
achieves the same purpose. To begin with, as we have discussed
earlier, clean water is not the only purpose of the
statute. So is the preservation of primary state responsibility for
ordinary land-use decisions. 33 U. S. C. §1251(b). Justice
Kennedy’s test takes no account of this purpose. More
fundamentally, however, the test simply rewrites the statute, using
for that purpose the gimmick of “significant nexus.” It would have
been an easy matter for Congress to give the Corps jurisdiction
over all wetlands (or, for that matter, all dry lands) that
“significantly affect the chemical, physical, and biological
integrity of ” waters of the United States. It did not do
that, but instead explicitly limited jurisdiction to “waters of the
United States.”

															   Justice Kennedy’s disposition would disallow
some of the Corps’ excesses, and in that respect is a more moderate
flouting of statutory command than Justice Stevens’.[ Footnote 15 ] In another respect, however,
it is more extreme. At least Justice Stevens can blame his
implausible reading of the statute upon the Corps. His error
consists of giving that agency more deference than reason permits.
Justice Kennedy, however, has devised his new statute all on his
own. It purports to be, not a grudging acceptance of an agency’s
close-to-the-edge expansion of its own powers, but rather the most reasonable interpretation of the law. It is far
from that, unless whatever affects waters is waters.

															VIII

															   Because the Sixth Circuit applied
the wrong standard to determine if these wetlands are covered
“waters of the United States,” and because of the paucity of the
record in both of these cases, the lower courts should determine,
in the first instance, whether the ditches or drains near each
wetland are “waters” in the ordinary sense of containing a
relatively permanent flow; and (if they are) whether the wetlands
in question are “adjacent” to these “waters” in the sense of
possessing a continuous surface connection that creates the
boundary-drawing problem we addressed in Riverside
Bayview .

															*  *  *

															   We vacate the judgments of the
Sixth Circuit in both No. 04–1034 and No. 04–1384, and remand both
cases for further proceedings. It is so ordered. Footnote 1 In issuing permits, the Corps directs
that “[a]ll factors which may be relevant to the proposal must be
considered including the cumulative effects thereof: among those
are conservation, economics, aesthetics, general environmental
concerns, wetlands, historic properties, fish and wildlife values,
flood hazards, floodplain values, land use, navigation, shore
erosion and accretion, recreation, water supply and conservation,
water quality, energy needs, safety, food and fiber production,
mineral needs, considerations of property ownership and, in
general, the needs and welfare of the people.” §320.4(a). Footnote 2 We are indebted to the Sonoran court
for a famous exchange, from the movie Casablanca (Warner Bros.
1942), which portrays most vividly the absurdity of finding the
desert filled with waters:

															“ ‘Captain Renault [Claude Rains]: “What in heaven’s name
brought you to Casablanca?”

															“ ‘Rick [Humphrey Bogart]: “My health. I came to Casablanca
for the waters.”

															“ ‘Captain Renault: “The waters? What waters? We’re in the
desert.”

															“ ‘Rick: “I was misinformed.’ ” 408 F. 3d, at
1117. Footnote 3 One possibility, which we ultimately find
unsatisfactory, is that the “other” waters covered by 33 U.
S. C. §1344(g)(1) are strictly intrastate waters that
are traditionally navigable. But it would be unreasonable to
interpret “the waters of the United States” to include all and only
traditional navigable waters, both interstate and intrastate. This
would preserve the traditional import of the qualifier “navigable”
in the defined term “navigable waters,” at the cost of
depriving the qualifier “of the United States” in the definition of all meaning. As traditionally understood,
the latter qualifier excludes intrastate waters, whether navigable
or not. See The Daniel Ball , 10 Wall. 557, 563 (1871). In SWANCC , we held that “navigable” retained something of its
traditional import. 531 U. S., at 172. A fortiori , the
phrase “of the United States” in the definition retains some of its
traditional meaning. Footnote 4 Justice Kennedy observes, post , at
13 (opinion concurring in judgment), that the dictionary approves
an alternative, somewhat poetic usage of “waters” as connoting “[a]
flood or inundation; as the waters have fallen. ‘The peril
of waters , wind, and rocks.’ Shak. ” Webster’s
Second 2882. It seems to us wholly unreasonable to interpret the
statute as regulating only “floods” and “inundations” rather than
traditional waterways—and strange to suppose that Congress had
waxed Shakespearean in the definition section of an otherwise
prosaic, indeed downright tedious, statute. The duller and more
commonplace meaning is obviously intended. Footnote 5 By describing “waters” as “relatively
permanent,” we do not necessarily exclude streams, rivers, or lakes
that might dry up in extraordinary circumstances, such as drought.
We also do not necessarily exclude seasonal rivers, which
contain continuous flow during some months of the year but no flow
during dry months—such as the 290-day, continuously flowing stream
postulated by Justice Stevens’ dissent (hereinafter the dissent), post , at 15. Common sense and common usage distinguish
between a wash and seasonal river.

															   Though scientifically precise distinctions
between “perennial” and “intermittent” flows are no doubt
available, see, e.g. , Dept. of Interior, U. S. Geological
Survey, E. Hedman & W. Osterkamp, Streamflow Characteristics
Related to Channel Geometry of Streams in Western United States 15
(1982) (Water-Supply Paper 2193), we have no occasion in this
litigation to decide exactly when the drying-up of a stream bed is
continuous and frequent enough to disqualify the channel as a
“wate[r] of the United States.” It suffices for present purposes
that channels containing permanent flow are plainly within the
definition, and that the dissent’s “intermittent” and “ephemeral”
streams, post , at 16 (opinion of Stevens, J.)—that is,
streams whose flow is “[c]oming and going at intervals … [b]roken,
fitful,” Webster’s Second 1296, or “existing only, or no longer
than, a day; diurnal … short-lived,” id. , at 857—are
not. Footnote 6 The principal definition of “stream” likewise
includes reference to such permanent, geographically fixed bodies
of water: “[a] current or course of water or other fluid, flowing
on the earth, as a river, brook, etc. ” Id., at
2493 (emphasis added). The other definitions of “stream” repeatedly
emphasize the requirement of continuous flow: “[a] steady flow , as of water, air, gas, or the like”;
“[a]nything issuing or moving with continued succession of
parts”; “[a] continued current or course; current; drift.” Ibid. (emphases added). The definition of the verb form of
“stream” contains a similar emphasis on continuity: “[t]o issue or
flow in a stream; to issue freely or move in a continuous flow
or course .” Ibid. (emphasis added). On these
definitions, therefore, the Corps’ phrases “intermittent streams,”
33 CFR §328.3(a)(3) (2004), and “ephemeral streams,” 65 Fed. Reg.
12823 (2000), are—like Senator Bentsen’s “ ‘ flowing
gullies,’ ” post , at 16, n. 11 (opinion of
Stevens, J.)—useful oxymora. Properly speaking, such entities
constitute extant “streams” only while they are “continuous[ly]
flow[ing]”; and the usually dry channels that contain them are
never “streams.” Justice Kennedy apparently concedes that “an
intermittent flow can constitute a stream” only “ while it is
flowing ,” post , at 13 (emphasis added)—which would
mean that the channel is a “water” covered by the Act only during
those times when water flow actually occurs. But no one contends
that federal jurisdiction appears and evaporates along with the
water in such regularly dry channels. Footnote 7 It is of course true, as the dissent and
Justice Kennedy both observe, that ditches, channels, conduits and
the like “can all hold water permanently as well as
intermittently,” post , at 17 (opinion of Stevens, J.); see
also post , at 14–15 (opinion of Kennedy, J.). But when
they do, we usually refer to them as “rivers,” “creeks,” or
“streams.” A permanently flooded ditch around a castle is
technically a “ditch,” but (because it is permanently filled with
water) we normally describe it as a “moat.” See Webster’s Second
1575. And a permanently flooded man-made ditch used for navigation
is normally described, not as a “ditch,” but as a “canal.” See id., at 388. Likewise, an open channel through which water
permanently flows is ordinarily described as a “stream,” not as a
“channel,” because of the continuous presence of water. This
distinction is particularly apt in the context of a statute
regulating water quality, rather than (for example) the
shape of stream beds. Cf. Jennison v. Kirk , 98 U. S. 453 ,
454–456 (1879) (referring to man-made channels as “ditches” when
the alleged injury arose from physical damage to the banks of the ditch); PUD No. 1 of Jefferson Cty. v. Washington Dept. of Ecology , 511 U. S. 700 , 709
(1994) (referring to a water-filled tube as a “tunnel” in order to
describe the shape of the conveyance, not the fact that it
was water-filled), both cited post , at 17, n. 12
(opinion of Stevens, J.). On its only natural reading, such a
statute that treats “waters” separately from “ditch[es],
channel[s], tunnel[s], and conduit[s],” thereby distinguishes
between continuously flowing “waters” and channels containing only
an occasional or intermittent flow.

															   It is also true that highly artificial,
manufactured, enclosed conveyance systems—such as “sewage treatment
plants,” post , at 15 (opinion of Kennedy, J.), and the
“mains, pipes, hydrants, machinery, buildings, and other
appurtenances and incidents” of the city of Knoxville’s “system of
waterworks,” Knoxville Water Co. v. Knoxville , 200 U. S. 22 , 27
(1906), cited post , at 17, n. 12 (opinion of Stevens,
J.)—likely do not qualify as “waters of the United States,” despite
the fact that they may contain continuous flows of water. See post , at 15 (opinion of Kennedy, J.); post , at
17, n. 12 (opinion of Stevens, J.). But this does not
contradict our interpretation, which asserts that relatively
continuous flow is a necessary condition for qualification
as a “water,” not an adequate condition. Just as ordinary
usage does not treat typically dry beds as “waters,” so also it
does not treat such elaborate, man-made, enclosed systems as
“waters” on a par with “streams,” “rivers,” and “oceans.” Footnote 8 Justice Kennedy contends that the Corps’
preservation of the “responsibilities and rights” of the States is
adequately demonstrated by the fact that “33 States and the
District of Columbia have filed an amici brief in this
litigation” in favor of the Corps’ interpretation, post ,
at 20. But it makes no difference to the statute ’s stated
purpose of preserving States’ “rights and responsibilities,”
§1251(b), that some States wish to unburden themselves of them.
Legislative and executive officers of the States may be content to
leave “responsibilit[y]” with the Corps because it is attractive to
shift to another entity controversial decisions disputed between
politically powerful, rival interests. That, however, is not what
the statute provides. Footnote 9 Justice Kennedy objects that our reliance on
these two clear-statement rules is inappropriate because “the
plurality’s interpretation does not fit the avoidance concerns that
it raises,” post , at 19—that is, because our resolution
both eliminates some jurisdiction that is clearly constitutional
and traditionally federal, and retains some that is questionably
constitutional and traditionally local. But a clear-statement rule
can carry one only so far as the statutory text permits. Our
resolution, unlike Justice Kennedy’s, keeps both the overinclusion
and the underinclusion to the minimum consistent with the statutory
text. Justice Kennedy’s reading—despite disregarding the text—fares
no better than ours as a precise “fit” for the “avoidance concerns”
that he also acknowledges. He admits, post , at 25, that
“the significant nexus requirement may not align perfectly with the
traditional extent of federal authority” over navigable waters—an
admission that “tests the limits of understatement,” Gonzales v. Oregon , 126 S. Ct. 904, 932
(2005) (Scalia, J., dissenting)—and it aligns even worse with the
preservation of traditional state land-use regulation. Footnote 10 Since the wetlands at issue in Riverside
Bayview actually abutted waters of the United States, the case
could not possibly have held that merely “neighboring” wetlands
came within the Corps’ jurisdiction. Obiter approval of
that proposition might be inferred, however, from the opinion’s
quotation without comment of a statement by the Corps describing
covered “adjacent” wetlands as those “ ‘that form the border
of or are in reasonable proximity to other waters of the
United States.’ ” 474 U. S., at 134 (quoting 42 Fed. Reg.
37128 (1977); emphasis added). The opinion immediately reiterated,
however, that adjacent wetlands could be regarded as “the waters of
the United States” in view of “the inherent difficulties of
defining precise bounds to regulable waters,” 474 U. S., at 134—a
rationale that would have no application to physically separated
“neighboring” wetlands. Given that the wetlands at issue in Riverside Bayview themselves “actually abut[ted] on a
navigable waterway,” id. , at 135; given that our opinion
recognized that unconnected wetlands could not naturally be
characterized as “ ‘waters’ ” at all, id. , at
132; and given the repeated reference to the difficulty of
determining where waters end and wetlands begin; the most natural
reading of the opinion is that a wetlands’ mere “reasonable
proximity” to waters of the United States is not enough to confer
Corps jurisdiction. In any event, as discussed in our immediately
following text, any possible ambiguity has been eliminated by SWANCC, 531 U. S. 159 (2001). Footnote 11 The dissent argues that “the very existence
of words like ‘alluvium’ and ‘silt’ in our language suggests that
at least some [dredged or fill material] makes its way downstream,” post , at 22 (citation omitted). See also post , at
17 (opinion of Kennedy, J.). By contrast, amici cite
multiple empirical analyses that contradict the dissent’s
philological approach to sediment erosion—including one which
concludes that “[t]he idea that the discharge of dredged or fill
material into isolated waters, ephemeral drains or non-tidal
ditches will pollute navigable waters located any appreciable
distance from them lacks credibility.” R. Pierce, Technical
Principles Related to Establishing the Limits of Jurisdiction for
Section 404 of the Clean Water Act 34–40 (Apr. 2003), available at
www.wetlandtraining.com/tpreljscwa.pdf, cited in Brief for
International Council of Shopping Centers et al. as Amici
Curiae 26–27; Brief for Pulte Homes, Inc., et al. as Amici Curiae 20–21; Brief for Foundation for Environmental
and Economic Progress et al. as Amici Curiae 29, and
n. 53 (“Fill material does not migrate”). Such scientific analysis
is entirely unnecessary, however, to reach the unremarkable
conclusion that the deposit of mobile pollutants into
upstream ephemeral channels is naturally described as an “addition
… to navigable waters,” 33 U. S. C. §1362(12), while the
deposit of stationary fill material generally is not. Footnote 12 Nor does the passing reference to “wetlands
adjacent thereto” in §1344(g)(1) purport to expand that statutory
definition. As the dissent concedes, post , at 20, that
reference merely confirms that the statutory definition can be read
to include some wetlands—namely, those that directly
“abut” covered waters. Riverside Bayview explicitly
acknowledged that §1344(g)(1) “does not conclusively determine the
construction to be placed on the use of the term ‘waters’ elsewhere
in the Act (particularly in [§1362(7)], which contains the
relevant definition of ‘navigable waters’); however, … it does
at least suggest strongly that the term ‘waters’ as used in the Act does not necessarily exclude ‘wetlands.’ ” 474 U. S.,
at 138, n. 11 (emphases added). Footnote 13 The sole exception is in Justice Kennedy’s
opinion, which argues that Riverside Bayview rejected our
physical-connection requirement by accepting as a given that any wetland formed by inundation from covered waters
(whether or not continuously connected to them) is covered by the
Act: “The Court in Riverside Bayview … did not suggest
that a flood-based origin would not support jurisdiction; indeed,
it presumed the opposite. See 474 U. S., at 134 (noting that the
Corps’ view was valid ‘ even for wetlands that are not the
result of flooding or permeation’ (emphasis added)).” Post , at 16. Of course Justice Kennedy himself fails to
observe this supposed presumption, since his “significant nexus”
test makes no exception for wetlands created by inundation. In any
event, the language from Riverside Bayview in Justice
Kennedy’s parenthetical is wrenched out of context. The sentence
which Justice Kennedy quotes in part immediately followed the
Court’s conclusion that “adjacent” wetlands are included because of
“the inherent difficulties of defining precise bounds to regulable
waters,” 474 U. S., at 134. And the full sentence reads as follows:
“This holds true even for wetlands that are not the result of
flooding or permeation by water having its source in adjacent bodies of open water,” ibid. (emphasis
added). Clearly, the “wetlands” referred to in the sentence are
only “adjacent” wetlands—namely, those with the continuous physical
connection that the rest of the Riverside Bayview opinion
required, see supra , at 21–23. Thus, it is evident that
the quoted language was not at all a rejection of the
physical-connection requirement, but rather a rejection of the
alternative position (which had been adopted by the lower court in
that case, see id. , at 125) that the only covered
wetlands are those created by inundation. As long as the wetland is
“adjacent” to covered waters, said Riverside Bayview , its
creation vel non by inundation is irrelevant. Footnote 14 The allusion is to a classic story told in
different forms and attributed to various authors. See, e.g., Geertz, Thick Description: Toward an Interpretive
Theory of Culture, in The Interpretation of Cultures 28–29 (1973).
In our favored version, an Eastern guru affirms that the earth is
supported on the back of a tiger. When asked what supports the
tiger, he says it stands upon an elephant; and when asked what
supports the elephant he says it is a giant turtle. When asked,
finally, what supports the giant turtle, he is briefly taken aback,
but quickly replies “Ah, after that it is turtles all the way
down.” Footnote 15 It is unclear how much more moderate
the flouting is, since Justice Kennedy’s “significant nexus”
standard is perfectly opaque. When, exactly, does a wetland
“significantly affect” covered waters, and when are its effects “in
contrast … speculative or insubstantial”? Post , at 23.
Justice Kennedy does not tell us clearly—except to suggest, post , at 25, that “ ‘ “isolated” is generally a
matter of degree’ ” (quoting Leibowitz & Nadeau, Isolated
Wetlands: State-of-the-Science and Future Directions, 23 Wetlands
663, 669 (2003)). As the dissent hopefully observes, post ,
at 24, such an unverifiable standard is not likely to constrain an
agency whose disregard for the statutory language has been so long
manifested. In fact, by stating that “[i]n both the consolidated
cases before the Court the record contains evidence suggesting the
possible existence of a significant nexus according to the
principles outlined above,” post , at 26, Justice Kennedy
tips a wink at the agency, inviting it to try its same expansive
reading again. KENNEDY, J., CONCURRING IN JUDGMENT RAPANOS V. UNITED STATES 547 U. S. ____ (2006) SUPREME COURT OF THE UNITED STATES NOS. 04-1034 AND 04-1384 JOHN A. RAPANOS, et ux., et al.,
PETITIONERS

															04–1034 v. UNITED STATES JUNE CARABELL et al., PETITIONERS

															04–1384 v. UNITED STATES ARMY CORPS OF ENGINEERS
et al. on writs of certiorari to the united states
court of appeals for the sixth circuit [June 19, 2006] Justice Kennedy ,
concurring in the judgment.

															   These consolidated cases require
the Court to decide whether the term “navigable waters” in the
Clean Water Act extends to wetlands that do not contain and are not
adjacent to waters that are navigable in fact. In Solid Waste
Agency of Northern Cook Cty. v. Army Corps of
Engineers, 531
U. S. 159 (2001) (SWANCC), the Court held, under the
circumstances presented there, that to constitute “ ‘navigable
waters’ ” under the Act, a water or wetland must possess a
“significant nexus” to waters that are or were navigable in fact or
that could reasonably be so made. Id. , at 167, 172. In the
instant cases neither the plurality opinion nor the dissent by
Justice Stevens chooses to apply this test; and though the Court of
Appeals recognized the test’s applicability, it did not consider
all the factors necessary to determine whether the lands in
question had, or did not have, the requisite nexus. In my view the
cases ought to be remanded to the Court of Appeals for proper
consideration of the nexus requirement.

															I

															   Although both the plurality
opinion and the dissent by Justice Stevens (hereinafter the
dissent) discuss the background of these cases in some detail, a
further discussion of the relevant statutes, regulations, and facts
may clarify the analysis suggested here.

															A

															   The “objective” of the Clean
Water Act (Act), is “to restore and maintain the chemical,
physical, and biological integrity of the Nation’s waters.” 33 U.
S. C. §1251(a). To that end, the statute, among other things,
prohibits “the discharge of any pollutant by any person” except as
provided in the Act. §1311(a). As relevant here, the term
“discharge of a pollutant” means “any addition of any pollutant to
navigable waters from any point source.” §1362(12). The term
“pollutant” is defined as “dredged spoil, solid waste, incinerator
residue, sewage, garbage, sewage sludge, munitions, chemical
wastes, biological materials, radioactive materials, heat, wrecked
or discarded equipment, rock, sand, cellar dirt and industrial,
municipal, and agricultural waste discharged into water.” §1362(6).
The Secretary of the Army, acting through the Chief of Engineers of
the Army Corps of Engineers, may issue permits for “discharge of
dredged or fill material into the navigable waters at specified
disposal sites.” §§1344(a), (c), (d); but see §1344(f)
(categorically exempting certain forms of “discharge of dredged or
fill material” from regulation under §1311(a)). Pursuant to
§1344(g), States with qualifying programs may assume certain
aspects of the Corps’ permitting responsibility. Apart from dredged
or fill material, pollutant discharges require a permit from the
Environmental Protection Agency (EPA), which also oversees the
Corps’ (and qualifying States’) permitting decisions. See
§§1311(a), 1342(a), 1344(c). Discharge of pollutants without an
appropriate permit may result in civil or criminal liability. See
§1319.

															   The statutory term to be
interpreted and applied in the two instant cases is the term
“navigable waters.” The outcome turns on whether that phrase
reasonably describes certain Michigan wetlands the Corps seeks to
regulate. Under the Act “[t]he term ‘navigable waters’ means the
waters of the United States, including the territorial seas.”
§1362(7). In a regulation the Corps has construed the term “waters
of the United States” to include not only waters susceptible to use
in interstate commerce—the traditional understanding of the term
“navigable waters of the United States,” see, e.g., United States v. Appalachian Elec. Power Co., 311 U. S. 377 ,
406–408 (1940); The Daniel Ball, 10 Wall. 557, 563–564
(1871)—but also tributaries of those waters and, of particular
relevance here, wetlands adjacent to those waters or their
tributaries. 33 CFR §§328.3(a)(1), (5), (7) (2005). The Corps views
tributaries as within its jurisdiction if they carry a perceptible
“ordinary high water mark.” §328.4(c); 65 Fed. Reg. 12823 (2000).
An ordinary high-water mark is a “line on the shore established by
the fluctuations of water and indicated by physical characteristics
such as clear, natural line impressed on the bank, shelving,
changes in the character of soil, destruction of terrestrial
vegetation, the presence of litter and debris, or other appropriate
means that consider the characteristics of the surrounding areas.”
33 CFR §328.3(e).

															   Contrary to the plurality’s description, ante , at 2–3, 15, wetlands are not simply moist patches of
earth. They are defined as “those areas that are inundated or
saturated by surface or ground water 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 generally include swamps,
marshes, bogs, and similar areas.” §328.3(b). The Corps’ Wetlands
Delineation Manual, including over 100 pages of technical guidance
for Corps officers, interprets this definition of wetlands to
require: (1) prevalence of plant species typically adapted to
saturated soil conditions, determined in accordance with the United
States Fish and Wildlife Service’s National List of Plant Species
that Occur in Wetlands; (2) hydric soil, meaning soil that is
saturated, flooded, or ponded for sufficient time during the
growing season to become anaerobic, or lacking in oxygen, in the
upper part; and (3) wetland hydrology, a term generally requiring
continuous inundation or saturation to the surface during at least
five percent of the growing season in most years. See Wetlands
Research Program Technical Report Y–87–1 (on-line edition), pp.
12–34 (Jan. 1987),
http://www.saj.usace.army.mil/permit/documents/87manual.pdf (all
Internet material as visited June 16, 2006, and available in Clerk
of Court’s case file). Under the Corps’ regulations, wetlands are
adjacent to tributaries, and thus covered by the Act, even if they
are “separated from other waters of the United States by man-made
dikes or barriers, natural river berms, beach dunes and the like.”
§328.3(c).

															B

															   The first consolidated case
before the Court, Rapanos v. United States , No.
04–1034, relates to a civil enforcement action initiated by the
United States in the United States District Court for the Eastern
District of Michigan against the owners of three land parcels near
Midland, Michigan. The first parcel, known as the Salzburg site,
consists of roughly 230 acres. The District Court, applying the
Corps’ definition of wetlands, found based on expert testimony that
the Salzburg site included 28 acres of wetlands. The District Court
further found that “the Salzburg wetlands have a surface water
connection to tributaries of the Kawkawlin River which, in turn,
flows into the Saginaw River and ultimately into Lake Huron.” App.
to Pet. for Cert. B11. Water from the site evidently spills into
the Hoppler Drain, located just north of the property, which
carries water into the Hoppler Creek and thence into the Kawkawlin
River, which is navigable. A state official testified that he
observed carp spawning in a ditch just north of the property,
indicating a direct surface-water connection from the ditch to the
Saginaw Bay of Lake Huron.

															   The second parcel, known as the
Hines Road site, consists of 275 acres, which the District Court
found included 64 acres of wetlands. The court found that the
wetlands have a surface-water connection to the Rose Drain, which
carries water into the Tittabawassee River, a navigable waterway.
The final parcel, called the Pine River site, consists of some 200
acres. The District Court found that 49 acres were wetlands and
that a surface water connection linked the wetlands to the nearby
Pine River, which flows into Lake Huron.

															   At all relevant times, John Rapanos owned the
Salzburg site; a company he controlled owned the Hines Road site;
and Rapanos’ wife and a company she controlled (possibly in
connection with another entity) owned the Pine River site. All
these parties are petitioners here. In December 1988, Mr. Rapanos,
hoping to construct a shopping center, asked the Michigan
Department of Natural Resources to inspect the Salzburg site. A
state official informed Rapanos that while the site likely included
regulated wetlands, Rapanos could proceed with the project if the
wetlands were delineated (that is, identified and preserved) or if
a permit were obtained. Pursuing the delineation option, Rapanos
hired a wetlands consultant to survey the property. The results
evidently displeased Rapanos: Informed that the site included
between 48 and 58 acres of wetlands, Rapanos allegedly threatened
to “destroy” the consultant unless he eradicated all traces of his
report. Rapanos then ordered $350,000-worth of earthmoving and
landclearing work that filled in 22 of the 64 wetlands acres on the
Salzburg site. He did so without a permit and despite receiving
cease-and-desist orders from state officials and the EPA. At the
Hines Road and Pine River sites, construction work—again conducted
in violation of state and federal compliance orders—altered an
additional 17 and 15 wetlands acres, respectively.

															   The Federal Government brought criminal
charges against Rapanos. In the suit at issue here, however, the
United States alleged civil violations of the Clean Water Act
against all the Rapanos petitioners. Specifically, the
Government claimed that petitioners discharged fill into
jurisdictional wetlands, failed to respond to requests for
information, and ignored administrative compliance orders. See 33
U. S. C. §§1311(a), 1318(a), 1319(a). After a 13-day bench
trial, the District Court made the findings noted earlier and, on
that basis, upheld the Corps’ jurisdiction over wetlands on the
three parcels. On the merits the court ruled in the Government’s
favor, finding that violations occurred at all three sites. As to
two other sites, however, the court rejected the Corps’ claim to
jurisdiction, holding that the Government had failed to carry its
burden of proving the existence of wetlands under the three-part
regulatory definition. (These two parcels are no longer at issue.)
The United States Court of Appeals for the Sixth Circuit affirmed.
376 F. 3d 629, 634 (2004). This Court granted certiorari to
consider the Corps’ jurisdiction over wetlands on the Salzburg,
Hines Road, and Pine River sites. 546 U. S. ___ (2005).

															   The second consolidated case, Carabell , No. 04–1384, involves a parcel shaped like a
right triangle and consisting of some 19.6 acres, 15.9 of which are
forested wetlands. 257 F. Supp. 2d 917, 923 (ED Mich. 2003).
The property is located roughly one mile from Lake St. Clair, a
430-square-mile lake located between Michigan and Canada that is
popular for boating and fishing and produces some 48 percent of the
sport fish caught in the Great Lakes, see Brief for Macomb County,
Michigan as Amicus Curiae 2. The right-angle corner of the
property is located to the northwest. The hypotenuse, which runs
from northeast to southwest, lies alongside a man-made berm that
separates the property from a ditch. At least under current
conditions—that is, without the deposit of fill in the wetlands
that the landowners propose—the berm ordinarily, if not always,
blocks surface-water flow from the wetlands into the ditch. But cf.
App. 186a (administrative hearing testimony by consultant for
Carabells indicating “you would start seeing some overflow” in a
“ten year storm”). Near the northeast corner of the property, the
ditch connects with the Sutherland-Oemig Drain, which carries water
continuously throughout the year and empties into Auvase Creek. The
creek in turn empties into Lake St. Clair. At its southwest end,
the ditch connects to other ditches that empty into the Auvase
Creek and thence into Lake St. Clair.

															   In 1993 petitioners Keith and June Carabell
sought a permit from the Michigan Department of Environmental
Quality (MDEQ), which has assumed permitting functions of the Corps
pursuant to §1344(g). Petitioners hoped to fill in the wetlands and
construct 130 condominium units. Although the MDEQ denied the
permit, a State Administrative Law Judge directed the agency to
approve an alternative plan, proposed by the Carabells, that
involved the construction of 112 units. This proposal called for
filling in 12.2 acres of the property while creating retention
ponds on 3.74 acres. Because the EPA had objected to the permit,
jurisdiction over the case transferred to the Corps. See
§1344(j).

															   The Corps’ district office concluded that the
Carabells’ property “provides water storage functions that, if
destroyed, could result in an increased risk of erosion and
degradation of water quality in the Sutherland-Oemig Drain, Auvase
Creek, and Lake St. Clair.” Id., at 127a. The district
office denied the permit, and the Corps upheld the denial in an
administrative appeal. The Carabells, challenging both the Corps’
jurisdiction and the merits of the permit denial, sought judicial
review pursuant to the Administrative Procedure Act, 5 U.
S. C. §706(2)(A). The United States District Court for the
Eastern District of Michigan granted summary judgment to the Corps,
257 F. Supp. 2d 917, and the United States Court of Appeals
for the Sixth Circuit affirmed, 391 F. 3d 704 (2005). This
Court granted certiorari to consider the jurisdictional question.
546 U. S. ___ (2005).

															II

															   Twice before the Court has
construed the term “navigable waters” in the Clean Water Act. In United States v. Riverside Bayview Homes, Inc., 474 U. S. 121 (1985), the Court upheld the Corps’ jurisdiction over wetlands
adjacent to navigable-in-fact waterways. Id. , at 139. The
property in Riverside Bayview , like the wetlands in the Carabell case now before the Court, was located roughly
one mile from Lake St. Clair, see United States v. Riverside Bayview Homes, Inc. , 729 F. 2d 391, 392
(CA6 1984) (decision on review in Riverside Bayview ),
though in that case, unlike Carabell , the lands at issue
formed part of a wetland that directly abutted a navigable-in-fact
creek, 474 U. S., at 131. In regulatory provisions that remain in
effect, the Corps had concluded that wetlands perform important
functions such as filtering and purifying water draining into
adjacent water bodies, 33 CFR §320.4(b)(2)(vii), slowing the flow
of runoff into lakes, rivers, and streams so as to prevent flooding
and erosion, §§320.4(b)(2)(iv), (v), and providing critical habitat
for aquatic animal species, §320.4(b)(2)(i). 474 U. S., at 134–135.
Recognizing that “[a]n agency’s construction of a statute it is
charged with enforcing is entitled to deference if it is reasonable
and not in conflict with the expressed intent of Congress,” id. , at 131 (citing Chemical Mfrs. Assn. v. Natural Resources Defense Council, Inc., 470 U. S. 116 , 125
(1985), and Chevron U. S. A. Inc. v. Natural
Resources Defense Council, Inc., 467 U. S. 837 , 842–845
(1984)), the Court held that “the Corps’ ecological judgment about
the relationship between waters and their adjacent wetlands
provides an adequate basis for a legal judgment that adjacent
wetlands may be defined as waters under the Act,” 474 U. S., at
134. The Court reserved, however, the question of the Corps’
authority to regulate wetlands other than those adjacent to open
waters. See id. , at 131–132, n. 8.

															   In SWANCC , the Court
considered the validity of the Corps’ jurisdiction over ponds and
mudflats that were isolated in the sense of being unconnected to
other waters covered by the Act. 531 U. S., at 171. The property at
issue was an abandoned sand and gravel pit mining operation where
“remnant excavation trenches” had “evolv[ed] into a scattering of
permanent and seasonal ponds.” Id. , at 163. Asserting
jurisdiction pursuant to a regulation called the “Migratory Bird
Rule,” the Corps argued that these isolated ponds were “waters of
the United States” (and thus “navigable waters” under the Act)
because they were used as habitat by migratory birds. Id. ,
at 164–165. The Court rejected this theory. “It was the significant
nexus between wetlands and ‘navigable waters,’ ” the Court
held, “that informed our reading of the [Act] in Riverside
Bayview Homes .” Id. , at 167. Because such a nexus was
lacking with respect to isolated ponds, the Court held that the
plain text of the statute did not permit the Corps’ action. Id. , at 172. Riverside Bayview and SWANCC establish the framework for the inquiry in the cases now before the
Court: Do the Corps’ regulations, as applied to the wetlands in Carabell and the three wetlands parcels in Rapanos , constitute a reasonable interpretation of
“navigable waters” as in Riverside Bayview or an invalid
construction as in SWANCC? Taken together these cases
establish that in some instances, as exemplified by Riverside
Bayview , the connection between a nonnavigable water or
wetland and a navigable water may be so close, or potentially so
close, that the Corps may deem the water or wetland a “navigable
water” under the Act. In other instances, as exemplified by SWANCC , there may be little or no connection. Absent a
significant nexus, jurisdiction under the Act is lacking. Because
neither the plurality nor the dissent addresses the nexus
requirement, this separate opinion, in my respectful view, is
necessary.

															A

															   The plurality’s opinion begins
from a correct premise. As the plurality points out, and as Riverside Bayview holds, in enacting the Clean Water Act
Congress intended to regulate at least some waters that are not
navigable in the traditional sense. Ante , at 12; Riverside Bayview, 474 U. S., at 133; see also SWANCC , supra , at 167. This conclusion is
supported by “the evident breadth of congressional concern for
protection of water quality and aquatic ecosystems.” Riverside
Bayview , supra , at 133; see also Milwaukee v. Illinois, 451 U. S. 304 , 318
(1981) (describing the Act as “an all-encompassing program of water
pollution regulation”). It is further compelled by statutory text,
for the text is explicit in extending the coverage of the Act to
some nonnavigable waters. In a provision allowing States to assume
some regulatory functions of the Corps (an option Michigan has
exercised), the Act limits States to issuing permits for:

															“the discharge of dredged or fill material into the
navigable waters (other than those waters which are presently used,
or are susceptible to use in their natural condition or by
reasonable improvement as a means to transport interstate or
foreign commerce shoreward to their ordinary high water mark,
including all waters which are subject to the ebb and flow of the
tide shoreward to their ordinary high water mark, or mean higher
high water mark on the west coast, including wetlands adjacent
thereto) within its jurisdiction.” 33 U. S. C.
§1344(g)(1).

															Were there no Clean Water Act “navigable waters”
apart from waters “presently used” or “susceptible to use” in
interstate commerce, the “other than” clause, which begins the long
parenthetical statement, would overtake the delegation of authority
the provision makes at the outset. Congress, it follows, must have
intended a broader meaning for navigable waters. The mention of
wetlands in the “other than” clause, moreover, makes plain that at
least some wetlands fall within the scope of the term “navigable
waters.” See Riverside Bayview , supra , at
138–139, and n. 11.

															   From this reasonable beginning the plurality
proceeds to impose two limitations on the Act; but these
limitations, it is here submitted, are without support in the
language and purposes of the Act or in our cases interpreting it.
First, because the dictionary defines “waters” to mean “water ‘[a]s
found in streams and bodies forming geographical features such as
oceans, rivers, [and] lakes,’ or ‘the flowing or moving masses, as
of waves or floods, making up such streams or bodies,” ante , at 13 (quoting Webster’s New International
Dictionary 2882 (2d ed. 1954) (hereinafter Webster’s Second)), the
plurality would conclude that the phrase “navigable waters” permits
Corps and EPA jurisdiction only over “relatively permanent,
standing or flowing bodies of water,” ante , at 13–14—a
category that in the plurality’s view includes “seasonal” rivers,
that is, rivers that carry water continuously except during “dry
months,” but not intermittent or ephemeral streams, ante ,
at 13–15, and n. 5. Second, the plurality asserts that
wetlands fall within the Act only if they bear “a continuous
surface connection to bodies that are ‘waters of the United States’
in their own right”—waters, that is, that satisfy the plurality’s
requirement of permanent standing water or continuous flow. Ante , at 23–24.

															   The plurality’s first requirement—permanent
standing water or continuous flow, at least for a period of “some
months,” ante , at 13–14, and n. 5—makes little
practical sense in a statute concerned with downstream water
quality. The merest trickle, if continuous, would count as a
“water” subject to federal regulation, while torrents thundering at
irregular intervals through otherwise dry channels would not.
Though the plurality seems to presume that such irregular flows are
too insignificant to be of concern in a statute focused on
“waters,” that may not always be true. Areas in the western parts
of the Nation provide some examples. The Los Angeles River, for
instance, ordinarily carries only a trickle of water and often
looks more like a dry roadway than a river. See, e.g., B.
Gumprecht, The Los Angeles River: Its Life, Death, and Possible
Rebirth 1–2 (1999); Martinez, City of Angels’ Signature River
Tapped for Rebirth, Chicago Tribune, Apr. 10, 2005, section 1,
p. 8. Yet it periodically releases water-volumes so powerful
and destructive that it has been encased in concrete and steel over
a length of some 50 miles. See Gumprecht, supra , at 227.
Though this particular waterway might satisfy the plurality’s test,
it is illustrative of what often-dry watercourses can become when
rain waters flow. See, e.g., County of Los Angeles Dept.
of Public Works, Water Resources Division: 2002–2003 Hydrologic
Report, Runoff, Daily Discharge, F377–R BOUQUET CANYON CREEK at
Urbandale Avenue 11107860 Bouquet Creek Near Saugus, CA,
http://ladpw.org/wrd/report/0203/runoff/discharge.cfm (indicating
creek carried no flow for much of the year but carried 122 cubic
feet per second on Feb. 12, 2003).

															   To be sure, Congress could draw a line to
exclude irregular waterways, but nothing in the statute suggests it
has done so. Quite the opposite, a full reading of the dictionary
definition precludes the plurality’s emphasis on permanence: The
term “waters” may mean “flood or inundation,” Webster’s Second
2882, events that are impermanent by definition. Thus, although of
course the Act’s use of the adjective “navigable” indicates a focus
on waterways rather than floods, Congress’ use of “waters” instead
of “water,” ante , at 13, does not necessarily carry the
connotation of “relatively permanent, standing or flowing bodies of
water,” ante , at 13–14. (And contrary to the plurality’s
suggestion, ante , at 13, n. 4, there is no indication
in the dictionary that the “flood or inundation” definition is
limited to poetry.) In any event, even granting the plurality’s
preferred definition—that “waters” means “water ‘[a]s found in
streams and bodies forming geographical features such as oceans,
rivers, [and] lakes,’ ” ante , at 13 (quoting
Webster’s Second 2882)—the dissent is correct to observe that an
intermittent flow can constitute a stream, in the sense of
“ ‘a current or course of water or other fluid, flowing on the
earth,’ ” ante , at 14, n. 6 (quoting Webster’s
Second 2493), while it is flowing. See post , at 15–16
(Stevens, J., dissenting) (also noting Court’s use of the
phrase “ ‘intermittent stream’ ” in Harrisonville v. W. S. Dickey Clay Mfg. Co., 289 U. S. 334 ,
335 (1933)). It follows that the Corps can reasonably interpret the
Act to cover the paths of such impermanent streams.

															   Apart from the dictionary, the plurality
invokes Riverside Bayview to support its interpretation
that the term “waters” is so confined, but this reliance is
misplaced. To be sure, the Court there compared wetlands to
“rivers, streams, and other hydrographic features more
conventionally identifiable as ‘waters.’ ” 474 U. S., at 131.
It is quite a stretch to claim, however, that this mention of
hydrographic features “echoe[s]” the dictionary’s reference to “ ‘geographical features such as oceans, rivers,
[and] lakes.’ ” Ante , at 16 (quoting Webster’s Second
2882). In fact the Riverside Bayview opinion does not cite
the dictionary definition on which the plurality relies, and the
phrase “hydrographic features” could just as well refer to
intermittent streams carrying substantial flow to navigable waters.
See Webster’s Second 1221 (defining “hydrography” as “[t]he
description and study of seas, lakes, rivers, and other waters;
specif[ically] … [t]he measurement of flow and investigation of the
behavior of streams, esp[ecially] with reference to the control or
utilization of their waters”).

															   Also incorrect is the plurality’s attempt to
draw support from the statutory definition of “point source” as
“any discernible, confined and discrete conveyance, including but
not limited to any pipe, ditch, channel, tunnel, conduit, well,
discrete fissure, container, rolling stock, concentrated animal
feeding operation, or vessel or other floating craft, from which
pollutants are or may be discharged.” 33 U. S. C. §1362(14).
This definition is central to the Act’s regulatory structure, for
the term “discharge of a pollutant” is defined in relevant part to
mean “any addition of any pollutant to navigable waters from any
point source,” §1362(12). Interpreting the point-source definition,
the plurality presumes, first, that the point-source examples
describe “watercourses through which intermittent waters
typically flow,” and second, that point sources and navigable
waters are “separate and distinct categories.” Ante , at
17. From this the plurality concludes, by a sort of negative
inference, that navigable waters may not be intermittent. The
conclusion is unsound. Nothing in the point-source definition
requires an intermittent flow. Polluted water could flow night and
day from a pipe, channel, or conduit and yet still qualify as a
point source; any contrary conclusion would likely exclude, among
other things, effluent streams from sewage treatment plants. As a
result, even were the statute read to require continuity of flow
for navigable waters, certain water-bodies could conceivably
constitute both a point source and a water. At any rate, as the
dissent observes, the fact that point sources may carry continuous
flow undermines the plurality’s conclusion that covered “waters”
under the Act may not be discontinuous. See post , at
17.

															   The plurality’s second limitation—exclusion of
wetlands lacking a continuous surface connection to other
jurisdictional waters—is also unpersuasive. To begin with, the
plurality is wrong to suggest that wetlands are
“ indistinguishable ” from waters to which they bear a
surface connection. Ante , at 37. Even if the precise
boundary may be imprecise, a bog or swamp is different from a
river. The question is what circumstances permit a bog, swamp, or
other nonnavigable wetland to constitute a “navigable water” under
the Act—as §1344(g)(1), if nothing else, indicates is sometimes
possible, see supra , at 10–11. Riverside Bayview addressed that question and its answer is inconsistent with the
plurality’s theory. There, in upholding the Corps’ authority to
regulate “wetlands adjacent to other bodies of water over which the
Corps has jurisdiction,” the Court deemed it irrelevant whether
“the moisture creating the wetlands … find[s] its source in the
adjacent bodies of water.” 474 U. S., at 135. The Court further
observed that adjacency could serve as a valid basis for regulation
even as to “wetlands that are not significantly intertwined with
the ecosystem of adjacent waterways.” Id. , at 135,
n. 9. “If it is reasonable,” the Court explained, “for the
Corps to conclude that in the majority of cases, adjacent wetlands
have significant effects on water quality and the aquatic
ecosystem, its definition can stand.” Ibid. The Court in Riverside Bayview did
note, it is true, the difficulty of defining where “water ends and
land begins,” id., at 132, and the Court cited that
problem as one reason for deferring to the Corps’ view that
adjacent wetlands could constitute waters. Given, however, the
further recognition in Riverside Bayview that an
overinclusive definition is permissible even when it reaches
wetlands holding moisture disconnected from adjacent water-bodies, id., at 135, and n. 9, Riverside Bayview ’s
observations about the difficulty of defining the water’s edge
cannot be taken to establish that when a clear boundary is evident,
wetlands beyond the boundary fall outside the Corps’
jurisdiction.

															   For the same reason Riverside Bayview also cannot be read as rejecting only the proposition, accepted by
the Court of Appeals in that case, that wetlands covered by the Act
must contain moisture originating in neighboring waterways. See id., at 125, 134. Since the Court of Appeals had accepted
that theory, the Court naturally addressed it. Yet to view the
decision’s reasoning as limited to that issue—an interpretation the
plurality urges here, ante , at 33, n. 13—would again
overlook the opinion’s broader focus on wetlands’ “significant
effects on water quality and the aquatic ecosystem,” 474 U. S., at
135, n. 9. In any event, even were this reading of Riverside Bayview correct, it would offer no support for
the plurality’s proposed requirement of a “continuous surface
connection,” ante , at 23. The Court in Riverside
Bayview rejected the proposition that origination in flooding
was necessary for jurisdiction over wetlands. It did not suggest
that a flood-based origin would not support jurisdiction; indeed,
it presumed the opposite. See 474 U. S., at 134 (noting that the
Corps’ view was valid “ even for wetlands that are not the
result of flooding or permeation” (emphasis added)). Needless to
say, a continuous connection is not necessary for moisture in
wetlands to result from flooding—the connection might well exist
only during floods. SWANCC , likewise, does not support
the plurality’s surface-connection requirement. SWANCC ’s
holding that “nonnavigable, isolated, intrastate waters,” 531 U.
S., at 171, are not “navigable waters” is not an explicit or
implicit overruling of Riverside Bayview ’s approval of
adjacency as a factor in determining the Corps’ jurisdiction. In
rejecting the Corps’ claimed authority over the isolated ponds in SWANCC , the Court distinguished adjacent nonnavigable
waters such as the wetlands addressed in Riverside
Bayview . 531 U. S., at 167, 170–171.

															   As Riverside Bayview recognizes, the
Corps’ adjacency standard is reasonable in some of its
applications. Indeed, the Corps’ view draws support from the
structure of the Act, while the plurality’s
surface-water-connection requirement does not.

															   As discussed above, the Act’s prohibition on
the discharge of pollutants into navigable waters, 33 U. S. C.
§1311(a), covers both the discharge of toxic materials such as
sewage, chemical waste, biological material, and radioactive
material and the discharge of dredged spoil, rock, sand, cellar
dirt, and the like. All these substances are defined as pollutants
whose discharge into navigable waters violates the Act. §§1311(a),
1362(6), (12). One reason for the parallel treatment may be that
the discharge of fill material can impair downstream water quality.
The plurality argues otherwise, asserting that dredged or fill
material “does not normally wash downstream.” Ante , at 26.
As the dissent points out, this proposition seems questionable as
an empirical matter. See post , at 22. It seems plausible
that new or loose fill, not anchored by grass or roots from other
vegetation, could travel downstream through waterways adjacent to a
wetland; at the least this is a factual possibility that the Corps’
experts can better assess than can the plurality. Silt, whether
from natural or human sources, is a major factor in aquatic
environments, and it may clog waterways, alter ecosystems, and
limit the useful life of dams. See, e.g., Fountain,
Unloved, But Not Unbuilt, N. Y. Times, June 5, 2005 section 4,
p. 3, col. 1; DePalma, Dam to Be Demolished to Save an
Endangered Species, N. Y. Times, Apr. 26, 2004, section B,
p. 1, col. 2; MacDougall, Damage Can Be Irreversible, Los
Angeles Times, June 19, 1987, pt. 1, p. 10, col. 4.

															   Even granting, however, the plurality’s
assumption that fill material will stay put, Congress’ parallel
treatment of fill material and toxic pollution may serve another
purpose. As the Court noted in Riverside Bayview , “the
Corps has concluded that wetlands may serve to filter and purify
water draining into adjacent bodies of water, 33 CFR
§320.4(b)(2)(vii) (1985), and to slow the flow of surface runoff
into lakes, rivers, and streams and thus prevent flooding and
erosion, see §§320.4(b)(2)(iv) and (v).” 474 U. S., at 134. Where
wetlands perform these filtering and runoff-control functions,
filling them may increase downstream pollution, much as a discharge
of toxic pollutants would. Not only will dirty water no longer be
stored and filtered but also the act of filling and draining itself
may cause the release of nutrients, toxins, and pathogens that were
trapped, neutralized, and perhaps amenable to filtering or
detoxification in the wetlands. See U. S. Congress, Office of
Technology Assessment, Wetlands: Their Use and Regulation,
OTA–O–206 pp. 43, 48–52 (Mar. 1984),
http://govinfo.library.unt.edu/ota/OTA_4/DATA/1984/8433.pdf
(hereinafter OTA). In many cases, moreover, filling in wetlands
separated from another water by a berm can mean that flood water,
impurities, or runoff that would have been stored or contained in
the wetlands will instead flow out to major waterways. With these
concerns in mind, the Corps’ definition of adjacency is a
reasonable one, for it may be the absence of an interchange of
waters prior to the dredge and fill activity that makes protection
of the wetlands critical to the statutory scheme.

															   In sum the plurality’s opinion is inconsistent
with the Act’s text, structure, and purpose. As a fallback the
plurality suggests that avoidance canons would compel its reading
even if the text were unclear. Ante , at 18–20. In SWANCC , as one reason for rejecting the Corps’ assertion
of jurisdiction over the isolated ponds at issue there, the Court
observed that this “application of [the Corps’] regulations” would
raise significant questions of Commerce Clause authority and
encroach on traditional state land-use regulation. 531 U. S., at
174. As SWANCC observed, ibid. , and as the
plurality points out here, ante , at 18, the Act states
that “[i]t is the policy of the Congress to recognize, preserve,
and protect the primary responsibilities and rights of States to
prevent, reduce, and eliminate pollution, [and] to plan the
development and use … of land and water resources,” 33 U.
S. C. §1251(b). The Court in SWANCC cited this
provision as evidence that a clear statement supporting
jurisdiction in applications raising constitutional and federalism
difficulties was lacking. 531 U. S., at 174.

															   The concerns addressed in SWANCC do
not support the plurality’s interpretation of the Act. In SWANCC , by interpreting the Act to require a significant
nexus with navigable waters, the Court avoided applications—those
involving waters without a significant nexus—that appeared likely,
as a category, to raise constitutional difficulties and federalism
concerns. Here, in contrast, the plurality’s interpretation does
not fit the avoidance concerns it raises. On the one hand, when a
surface-water connection is lacking, the plurality forecloses
jurisdiction over wetlands that abut navigable-in-fact waters—even
though such navigable waters were traditionally subject to federal
authority. On the other hand, by saying the Act covers wetlands
(however remote) possessing a surface-water connection with a
continuously flowing stream (however small), the plurality’s
reading would permit applications of the statute as far from
traditional federal authority as are the waters it deems beyond the
statute’s reach. Even assuming, then, that federal regulation of
remote wetlands and nonnavigable waterways would raise a difficult
Comerce Clause issue notwithstanding those waters’ aggregate
effects on national water quality, but cf. Wickard v. Filburn, 317 U. S. 111 (1942);
see also infra , at 25–26, the plurality’s reading is not
responsive to this concern. As for States’ “responsibilities and
rights,” §1251(b), it is noteworthy that 33 States plus the
District of Columbia have filed an amici brief in this
litigation asserting that the Clean Water Act is important to their
own water policies. See Brief for States of New York et al.
1–3. These amici note, among other things, that the Act
protects downstream States from out-of-state pollution that they
cannot themselves regulate. Ibid. It bears mention also that the plurality’s
overall tone and approach—from the characterization of acres of
wetlands destruction as “backfilling … wet fields,” ante ,
at 2, to the rejection of Corps authority over “man-made drainage
ditches” and “dry arroyos” without regard to how much water they
periodically carry, ante , at 15, to the suggestion,
seemingly contrary to Congress’ judgment, that discharge of fill
material is inconsequential for adjacent waterways, ante ,
at 26, and n. 11—seems unduly dismissive of the interests asserted
by the United States in these cases. Important public interests are
served by the Clean Water Act in general and by the protection of
wetlands in particular. To give just one example, amici here have noted that nutrient-rich runoff from the Mississippi
River has created a hypoxic, or oxygen-depleted, “dead zone” in the
Gulf of Mexico that at times approaches the size of Massachusetts
and New Jersey. Brief for Association of State Wetland Managers
et al. 21–23; Brief for Environmental Law Institute 23.
Scientific evidence indicates that wetlands play a critical role in
controlling and filtering runoff. See, e.g., OTA 43,
48–52; R. Tiner, In Search of Swampland: A Wetland Sourcebook and
Field Guide 93–95 (2d ed. 2005); Whitmire & Hamilton, Rapid
Removal of Nitrate and Sulfate in Freshwater Wetland Sediments, 34
J. Env. Quality 2062 (2005). It is true, as the plurality
indicates, that environmental concerns provide no reason to
disregard limits in the statutory text, ante , at 27, but
in my view the plurality’s opinion is not a correct reading of the
text. The limits the plurality would impose, moreover, give
insufficient deference to Congress’ purposes in enacting the Clean
Water Act and to the authority of the Executive to implement that
statutory mandate.

															   Finally, it should go without saying that
because the plurality presents its interpretation of the Act as the
only permissible reading of the plain text, ante , at 20,
23–24, the Corps would lack discretion, under the plurality’s
theory, to adopt contrary regulations. The Chief Justice suggests
that if the Corps and EPA had issued new regulations after SWANCC they would have “enjoyed plenty of room to operate
in developing some notion of an outer bound to the reach
of their authority” and thus could have avoided litigation of the
issues we address today. Ante , at 2. That would not
necessarily be true under the opinion The Chief Justice has joined.
New rulemaking could have averted the disagreement here only if the
Corps had anticipated the unprecedented reading of the Act that the
plurality advances.

															B

															   While the plurality reads
nonexistent requirements into the Act, the dissent reads a central
requirement out—namely, the requirement that the word “navigable”
in “navigable waters” be given some importance. Although the Court
has held that the statute’s language invokes Congress’ traditional
authority over waters navigable in fact or susceptible of being
made so, SWANCC , 531 U. S., at 172 (citing Appalachian
Power , 311 U. S., at 407–408), the dissent would permit
federal regulation whenever wetlands lie alongside a ditch or
drain, however remote and insubstantial, that eventually may flow
into traditional navigable waters. The deference owed to the Corps’
interpretation of the statute does not extend so far.

															   Congress’ choice of words creates
difficulties, for the Act contemplates regulation of certain
“navigable waters” that are not in fact navigable. Supra ,
at 10–11. Nevertheless, the word “navigable” in the Act must be
given some effect. See SWANCC , supra , at 172.
Thus, in SWANCC the Court rejected the Corps’ assertion of
jurisdiction over isolated ponds and mudflats bearing no evident
connection to navigable-in-fact waters. And in Riverside
Bayview , while the Court indicated that “the term ‘navigable’
as used in the Act is of limited import,” 474 U. S., at 133, it
relied, in upholding jurisdiction, on the Corps’ judgment 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,” id., at 135. The
implication, of course, was that wetlands’ status as “integral
parts of the aquatic environment”—that is, their significant nexus
with navigable waters—was what established the Corps’ jurisdiction
over them as waters of the United States.

															   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.
The required nexus must be assessed in terms of the statute’s goals
and purposes. Congress enacted the law to “restore and maintain the
chemical, physical, and biological integrity of the Nation’s
waters,” 33 U. S. C. §1251(a), and it pursued that objective
by restricting dumping and filling in “navigable waters,”
§§1311(a), 1362(12). With respect to wetlands, the rationale for
Clean Water Act regulation is, as the Corps has recognized, that
wetlands can perform critical functions related to the integrity of
other waters—functions such as pollutant trapping, flood control,
and runoff storage. 33 CFR §320.4(b)(2). Accordingly, wetlands
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 statutory term “navigable waters.”

															   Although the dissent acknowledges that
wetlands’ ecological functions vis-À-vis other covered waters are
the basis for the Corps’ regulation of them, post , at
10–11, it concludes that the ambiguity in the phrase “navigable
waters” allows the Corps to construe the statute as reaching all
“non-isolated wetlands,” just as it construed the Act to reach the
wetlands adjacent to navigable-in-fact waters in Riverside
Bayview , see post , at 11. This, though, seems
incorrect. The Corps’ theory of jurisdiction in these consolidated
cases—adjacency to tributaries, however remote and
insubstantial—raises concerns that go beyond the holding of Riverside Bayview; and so the Corps’ assertion of
jurisdiction cannot rest on that case.

															   As applied to wetlands adjacent to
navigable-in-fact waters, the Corps’ conclusive standard for
jurisdiction rests upon a reasonable inference of ecologic
interconnection, and the assertion of jurisdiction for those
wetlands is sustainable under the Act by showing adjacency alone.
That is the holding of Riverside Bayview . Furthermore,
although the Riverside Bayview Court reserved the question
of the Corps’ authority over “wetlands that are not adjacent to
bodies of open water,” 474 U. S., at 131–132, n. 8, and in any
event addressed no factual situation other than wetlands adjacent
to navigable-in-fact waters, it may well be the case that Riverside Bayview ’s reasoning—supporting jurisdiction
without any inquiry beyond adjacency—could apply equally to
wetlands adjacent to certain major tributaries. Through regulations
or adjudication, the Corps may choose to identify categories of
tributaries that, due to their volume of flow (either annually or
on average), their proximity to navigable waters, or other relevant
considerations, are significant enough that wetlands adjacent to
them are likely, in the majority of cases, to perform important
functions for an aquatic system incorporating navigable waters.

															   The Corps’ existing standard for tributaries,
however, provides no such assurance. As noted earlier, the Corps
deems a water a tributary if it feeds into a traditional navigable
water (or a tributary thereof) and possesses an ordinary high-water
mark, defined as a “line on the shore established by the
fluctuations of water and indicated by [certain] physical
characteristics,” §328.3(e). See supra , at 3. This
standard presumably provides a rough measure of the volume and
regularity of flow. Assuming it is subject to reasonably consistent
application, but see U. S. General Accounting Office, Report to the
Chairman, Subcommittee on Energy Policy, Natural Resources and
Regulating Affairs, Committee on Reform, House of Representatives,
Waters and Wetlands: Corps of Engineers Needs to Evaluate Its
District Office Practices in Determining Jurisdiction, GAO–04–297
pp. 3–4 (Feb. 2004), http://www.gao.gov/new.items/d04297.pdf
(noting variation in results among Corps district offices), it may
well provide a reasonable measure of whether specific minor
tributaries bear a sufficient nexus with other regulated waters to
constitute “navigable waters” under the Act. Yet the breadth of
this standard—which seems to leave wide room for regulation of
drains, ditches, and streams remote from any navigable-in-fact
water and carrying only minor water-volumes towards it—precludes
its adoption as the determinative measure of whether adjacent
wetlands are likely to play an important role in the integrity of
an aquatic system comprising navigable waters as traditionally
understood. Indeed, in many cases wetlands adjacent to tributaries
covered by this standard might appear little more related to
navigable-in-fact waters than were the isolated ponds held to fall
beyond the Act’s scope in SWANCC . Cf. Leibowitz &
Nadeau, Isolated Wetlands: State-of-the-Science and Future
Directions, 23 Wetlands 663, 669 (2003) (noting that
“ ‘isolated’ is generally a matter of degree”).

															   When the Corps seeks to regulate wetlands
adjacent to navigable-in-fact waters, it may rely on adjacency to
establish its jurisdiction. Absent more specific regulations,
however, the Corps must establish a significant nexus on a
case-by-case basis when it seeks to regulate wetlands based on
adjacency to nonnavigable tributaries. Given the potential
overbreadth of the Corps’ regulations, this showing is necessary to
avoid unreasonable applications of the statute. Where an adequate
nexus is established for a particular wetland, it may be
permissible, as a matter of administrative convenience or
necessity, to presume covered status for other comparable wetlands
in the region. That issue, however, is neither raised by these
facts nor addressed by any agency regulation that accommodates the
nexus requirement outlined here.

															   This interpretation of the Act does not raise
federalism or Commerce Clause concerns sufficient to support a
presumption against its adoption. To be sure, the significant nexus
requirement may not align perfectly with the traditional extent of
federal authority. Yet in most cases regulation of wetlands that
are adjacent to tributaries and possess a significant nexus with
navigable waters will raise no serious constitutional or federalism
difficulty. Cf. Pierce County v. Guillen, 537 U. S. 12 9, 147 (2003) (upholding
federal legislation “aimed at improving safety in the channels of
commerce”); Oklahoma ex rel. Phillips v. Guy
F. Atkinson Co., 313 U. S. 508 , 524–525
(1941) (“[J]ust as control over the non-navigable parts of a river
may be essential or desirable in the interests of the navigable
portions, so may the key to flood control on a navigable stream be
found in whole or in part in flood control on its
tributaries … . [T]he exercise of the granted power of
Congress to regulate interstate commerce may be aided by
appropriate and needful control of activities and agencies which,
though intrastate, affect that commerce”). As explained earlier,
moreover, and as exemplified by SWANCC , the
significant-nexus test itself prevents problematic applications of
the statute. See supra , at 19–20; 531 U. S., at 174. The
possibility of legitimate Commerce Clause and federalism concerns
in some circumstances does not require the adoption of an
interpretation that departs in all cases from the Act’s text and
structure. See Gonzales v. Raich , 545 U. S. 1 , __ (2005)
(slip op., at 14) (“[W]hen a general regulatory statute bears a
substantial relation to commerce, the de minimis character
of individual instances arising under that statute is of no
consequence” (internal quotation marks omitted)).

															III

															   In both the consolidated cases
before the Court the record contains evidence suggesting the
possible existence of a significant nexus according to the
principles outlined above. Thus the end result in these cases and
many others to be considered by the Corps may be the same as that
suggested by the dissent, namely, that the Corps’ assertion of
jurisdiction is valid. Given, however, that neither the agency nor
the reviewing courts properly considered the issue, a remand is
appropriate, in my view, for application of the controlling legal
standard. Rapanos As the dissent points out, in
Rapanos , No. 04–1034, an expert whom the District Court found
“eminently qualified” and “highly credible,” App. to Pet. for Cert.
B7, testified that the wetlands were providing “habitat, sediment
trapping, nutrient recycling, and flood peak diminution, reduction
flow water augmentation.” 4 Tr. 96 (Apr. 5, 1999). Although the
expert had “not studied the upstream drainage of these sites” and
thus could not assert that the wetlands were performing important
pollutant-trapping functions, ibid., he did observe:

															“we have a situation in which the flood water
attenuation in that water is held on the site in the wetland … such
that it does not add to flood peak. By the same token it would have
some additional water flowing into the rivers during the drier
periods, thus, increasing the low water flow… . By the same
token on all of the sites to the extent that they slow the flow of
water off of the site they will also accumulate sediment and thus
trap sediment and hold nutrients for use in those wetlands systems
later in the season as well.” Id. , at 95–96.

															In addition, in assessing the hydrology prong of
the three-part wetlands test, see supra , at 3–4, the
District Court made extensive findings regarding water tables and
drainage on the parcels at issue. In applying the Corps’
jurisdictional regulations, the District Court found that each of
the wetlands bore surface water connections to tributaries of
navigable-in-fact waters.

															   Much the same evidence should permit the
establishment of a significant nexus with navigable-in-fact waters,
particularly if supplemented by further evidence about the
significance of the tributaries to which the wetlands are
connected. The Court of Appeals, however, though recognizing that
under SWANCC such a nexus was required for jurisdiction,
held that a significant nexus “can be satisfied by the presence of
a hydrologic connection.” 376 F. 3d, at 639. Absent some
measure of the significance of the connection for downstream water
quality, this standard was too uncertain. Under the analysis
described earlier, supra , at 22–23, 25, mere hydrologic
connection should not suffice in all cases; the connection may be
too insubstantial for the hydrologic linkage to establish the
required nexus with navigable waters as traditionally understood.
In my view this case should be remanded so that the District Court
may reconsider the evidence in light of the appropriate standard.
See, e.g., Pullman&nbhyph;Standard v. Swint, 456 U. S. 273 ,
291 (1982) (“When an appellate court discerns that a district court
has failed to make a finding because of an erroneous view of the
law, the usual rule is that there should be a remand for further
proceedings to permit the trial court to make the missing
findings”). Carabell In Carabell , No.
04–1384, the record also contains evidence bearing on the
jurisdictional inquiry. The Corps noted in deciding the
administrative appeal that “[b]esides the effects on wildlife
habitat and water quality, the [district office] also noted that
the project would have a major, long-term detrimental effect on
wetlands, flood retention, recreation and conservation and overall
ecology,” App. 218a. Similarly, in the district office’s permit
evaluation, Corps officers observed:

															“The proposed work would destroy/adversely impact
an area that retains rainfall and forest nutrients and would
replace it with a new source area for runoff pollutants. Pollutants
from this area may include lawn fertilizers, herbicides,
pesticides, road salt, oil, and grease. These pollutants would then
runoff directly into the waterway… . Overall, the operation
and use of the proposed activity would have a major, long term,
negative impact on water quality. The cumulative impacts of
numerous such projects would be major and negative as the few
remaining wetlands in the area are developed.” Id. , at
97a–98a.

															The Corps’ evaluation further noted that by
“eliminat[ing] the potential ability of the wetland to act as a
sediment catch basin,” the proposed project “would contribute to
increased runoff and accretion … along the drain and further
downstream in Auvase Creek.” Id. , at 98a. And it observed
that increased runoff from the site would likely cause downstream
areas to “see an increase in possible flooding magnitude and
frequency.” Id. , at 99a.

															   The conditional language in these
assessments—“potential ability,” “possible flooding”—could suggest
an undue degree of speculation, and a reviewing court must identify
substantial evidence supporting the Corps’ claims, see 5 U.
S. C. §706(2)(E). Nevertheless, the record does show that
factors relevant to the jurisdictional inquiry have already been
noted and considered. As in Rapanos , though, the record
gives little indication of the quantity and regularity of flow in
the adjacent tributaries—a consideration that may be important in
assessing the nexus. Also, as in Rapanos , the legal
standard applied to the facts was imprecise.

															   The Court of Appeals, considering the Carabell case after its Rapanos decision, framed
the inquiry in terms of whether hydrologic connection is required
to establish a significant nexus. The court held that it is not,
and that much of its holding is correct. Given the role wetlands
play in pollutant filtering, flood control, and runoff storage, it
may well be the absence of hydrologic connection (in the sense of
interchange of waters) that shows the wetlands’ significance for
the aquatic system. In the administrative decision under review,
however, the Corps based its jurisdiction solely on the wetlands’
adjacency to the ditch opposite the berm on the property’s edge. As
explained earlier, mere adjacency to a tributary of this sort is
insufficient; a similar ditch could just as well be located many
miles from any navigable-in-fact water and carry only insubstantial
flow towards it. A more specific inquiry, based on the significant
nexus standard, is therefore necessary. Thus, a remand is again
required to permit application of the appropriate legal standard.
See, e.g., INS v. Orlando Ventura, 537 U. S. 12 , 16
(2002) (per curiam) (“Generally speaking, a court of
appeals should remand a case to an agency for decision of a matter
that statutes place primarily in agency hands”).

															*  *  *

															   In these consolidated cases I
would vacate the judgments of the Court of Appeals and remand for
consideration whether the specific wetlands at issue possess a
significant nexus with navigable waters. ROBERTS, C. J., CONCURRING RAPANOS V. UNITED STATES 547 U. S. ____ (2006) SUPREME COURT OF THE UNITED STATES NOS. 04-1034 AND 04-1384 JOHN A. RAPANOS, et ux., et al.,
PETITIONERS

															04–1034 v. UNITED STATES JUNE CARABELL et al., PETITIONERS

															04–1384 v. UNITED STATES ARMY CORPS OF ENGINEERS
et al. on writs of certiorari to the united states
court of appeals for the sixth circuit [June 19, 2006] Chief Justice Roberts ,
concurring.

															   Five years ago, this Court
rejected the position of the Army Corps of Engineers on the scope
of its authority to regulate wetlands under the Clean Water Act, 86
Stat. 816, as amended, 33 U. S. C. §1251 et seq . Solid Waste Agency of Northern Cook Cty. v. Army Corps
of Engineers, 531 U. S. 159 (2001) (SWANCC) . The Corps had taken the view that its authority
was essentially limitless; this Court explained that such a
boundless view was inconsistent with the limiting terms Congress
had used in the Act. Id., at 167–174.

															   In response to the SWANCC decision,
the Corps and the Environmental Protection Agency (EPA) initiated a
rulemaking to consider “issues associated with the scope of waters
that are subject to the Clean Water Act (CWA), in light of the U.
S. Supreme Court decision in [SWANCC] .” 68 Fed. Reg. 1991
(2003). The “goal of the agencies” was “to develop proposed
regulations that will further the public interest by clarifying
what waters are subject to CWA jurisdiction and affording full
protection to these waters through an appropriate focus of Federal
and State resources consistent with the CWA.” Ibid. Agencies delegated rulemaking
authority under a statute such as the Clean Water Act are afforded
generous leeway by the courts in interpreting the statute they are
entrusted to administer. See Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 , 842–845
(1984). Given the broad, somewhat ambiguous, but nonetheless
clearly limiting terms Congress employed in the Clean Water Act,
the Corps and the EPA would have enjoyed plenty of room to operate
in developing some notion of an outer bound to the reach
of their authority.

															   The proposed rulemaking went nowhere. Rather
than refining its view of its authority in light of our decision in SWANCC , and providing guidance meriting deference under
our generous standards, the Corps chose to adhere to its
essentially boundless view of the scope of its power. The upshot
today is another defeat for the agency.

															   It is unfortunate that no opinion commands a
majority of the Court on precisely how to read Congress’ limits on
the reach of the Clean Water Act. Lower courts and regulated
entities will now have to feel their way on a case-by-case basis.
This situation is certainly not unprecedented. See Grutter v. Bollinger, 539 U. S. 306 , 325
(2003) (discussing Marks v. United States, 430 U. S. 188 (1977)). What is unusual in this instance, perhaps, is how readily
the situation could have been avoided.

															 The scope of the proposed rulemaking was not
as narrow as Justice Stevens suggests, post , at 10,
n. 4 (dissenting opinion). See 68 Fed. Reg. 1994 (2003)
(“Additionally, we invite your views as to whether any other
revisions are needed to the existing regulations on which waters
are jurisdictional under the CWA”); id., at 1992 (“Today’s
[notice of proposed rulemaking] seeks public input on what, if any,
revisions in light of SWANCC might be appropriate to the
regulations that define ‘waters of the U. S.’, and today’s [notice]
thus would be of interest to all entities discharging to,
or regulating, such waters ” (emphases added)). The
agencies can decide for themselves whether, as the SWANCC dissenter suggests, it was wise for them to take no action in
response to SWANCC. STEVENS, J., DISSENTING RAPANOS V. UNITED STATES 547 U. S. ____ (2006) SUPREME COURT OF THE UNITED STATES NOS. 04-1034 AND 04-1384 JOHN A. RAPANOS, et ux., et al.,
PETITIONERS

															04–1034 v. UNITED STATES JUNE CARABELL et al., PETITIONERS

															04–1384 v. UNITED STATES ARMY CORPS OF ENGINEERS
et al. on writs of certiorari to the united states
court of appeals for the sixth circuit [June 19, 2006] Justice Stevens , with
whom Justice Souter, Justice Ginsburg, and Justice Breyer join,
dissenting.

															   In 1972, Congress decided to
“restore and maintain the chemical, physical, and biological
integrity of the Nation’s waters” by passing what we now call the
Clean Water Act. 86 Stat. 816, as amended, 33 U. S. C. §1251 et
seq . The costs of achieving the Herculean goal of ending water
pollution by 1985, see §1251(a), persuaded President Nixon to veto
its enactment, but both Houses of Congress voted to override that
veto by overwhelming margins. To achieve its goal,
Congress prohibited “the discharge of any pollutant”—defined to
include “any addition of any pollutant to navigable waters from any
point source”—without a permit issued by the Army Corps of
Engineers (Army Corps or Corps) or the Environmental Protection
Agency (EPA). §§1311(a), 1362(12)(A). Congress further defined
“navigable waters” to mean “the waters of the United States.”
§1362(7). The narrow question presented
in No. 04–1034 is whether wetlands adjacent to tributaries of
traditionally navigable waters are “waters of the United States”
subject to the jurisdiction of the Army Corps; the question in No.
04–1384 is whether a manmade berm separating a wetland from the
adjacent tributary makes a difference. The broader question is
whether regulations that have protected the quality of our waters
for decades, that were implicitly approved by Congress, and that
have been repeatedly enforced in case after case, must now be
revised in light of the creative criticisms voiced by the plurality
and Justice Kennedy today. Rejecting more than 30 years of practice
by the Army Corps, the plurality disregards the nature of the
congressional delegation to the agency and the technical and
complex character of the issues at stake. Justice Kennedy similarly
fails to defer sufficiently to the Corps, though his approach is
far more faithful to our precedents and to principles of statutory
interpretation than is the plurality’s. In my view, the proper
analysis is straightforward. The Army Corps has determined that
wetlands adjacent to tributaries of traditionally navigable waters
preserve the quality of our Nation’s waters by, among other things,
providing habitat for aquatic animals, keeping excessive sediment
and toxic pollutants out of adjacent waters, and reducing
downstream flooding by absorbing water at times of high flow. The
Corps’ resulting decision to treat these wetlands as encompassed
within the term “waters of the United States” is a quintessential
example of the Executive’s reasonable interpretation of a statutory
provision. See Chevron U. S. A. Inc. v. Natural
Resources Defense Council, Inc., 467 U. S. 837 , 842–845
(1984). Our unanimous decision in United States v. Riverside Bayview Homes, Inc., 474 U. S. 121 (1985), was faithful to our duty to respect the work product of the
Legislative and Executive Branches of our Government. Today’s
judicial amendment of the Clean Water Act is not. I At each of the
three sites at issue in No. 04–1034, the petitioners filled large
areas of wetlands without permits, despite being on full notice of
the Corps’ regulatory requirements. Because the plurality gives
short shrift to the facts of this case—as well as to those of No.
04–1384—I shall discuss them at some length. The facts related
to the 230-acre Salzburg site are illustrative. In 1988, John
Rapanos asked the Michigan Department of Natural Resources (MDNR)
to inspect the site “in order to discuss with him the feasibility
of building a shopping center there.” App. to Pet. for Cert. in No.
04–1034, p. B15. An MDNR inspector informed Rapanos that the land
probably included wetlands that were “waters of the United States”
and sent him an application for a permit under §404 of the
Act.[ Footnote 1 ] Rapanos then
hired a wetland consultant, Dr. Frederick Goff. After Dr. Goff
concluded that the land did in fact contain many acres of wetlands,
“Rapanos threatened to ‘destroy’ Dr. Goff if he did not destroy the
wetland report, and refused to pay Dr. Goff unless and until he
complied.” Ibid. In the meantime, without applying for a
permit, Rapanos hired construction companies to do $350,000 worth
of work clearing the land, filling in low spots, and draining
subsurface water. After Rapanos prevented MDNR inspectors from
visiting the site, ignored an MDNR cease-and-desist letter, and
refused to obey an administrative compliance order issued by the
EPA, the matter was referred to the Department of Justice. In the
civil case now before us, the District Court found that Rapanos
unlawfully filled 22 acres of wetlands. Rapanos and his wife engaged
in similar behavior at the Hines Road and Pine River sites. Without
applying for §404 permits, they hired construction companies to
perform extensive clearing and filling activities. They continued
these activities even after receiving EPA administrative compliance
orders directing them to cease the work immediately. They
ultimately spent $158,000 at the 275-acre Hines Road site, filling
17 of its existing 64 acres of wetlands. At the 200-acre Pine River
site, they spent $463,000 and filled 15 of its 49 acres of
wetlands. Prior to their destruction,
the wetlands at all three sites had surface connections to
tributaries of traditionally navigable waters. The Salzburg
wetlands connected to a drain that flows into a creek that flows
into the navigable Kawkawlin River. The Hines Road wetlands
connected to a drain that flows into the navigable Tittabawassee
River. And the Pine River wetlands connected with the Pine River,
which flows into Lake Huron. At trial, the Government put
on a wetland expert, Dr. Daniel Willard, whom the trial court found
“eminently qualified” and “highly credible.” Id., at B7.
Dr. Willard testified that the wetlands at these three sites
provided ecological functions in terms of “habitat, sediment
trapping, nutrient recycling, and flood peak diminution.” 4 Tr. 96
(Apr. 5, 1999).[ Footnote 2 ] He
explained: “[G]enerally for all of the . . .
sites we have a situation in which the flood water attenuation in
that water is held on the site in the wetland . . . such that it
does not add to flood peak. By the same token it would have some
additional water flowing into the rivers during the drier periods,
thus, increasing low water flow. .     .     .     .     . “By the same token on all of the
sites to the extent that they slow the flow of water of the site
they will also accumulate sediment and thus trap sediment and hold
nutrients for use in those wetland systems later in the season as
well.” Id., at 95–96. The District Court found that the
wetlands at all three sites were covered by the Clean Water Act and
that the Rapanoses had violated the Act by destroying them without
permits. The Sixth Circuit unanimously affirmed. 376 F. 3d 629
(2004). The facts of No. 04–1384 are
less dramatic. The petitioners in that case own a 20-acre tract of
land, of which 16 acres are wetlands, located in Macomb County a
mile from Lake St. Clair. These wetlands border a ditch that flows
into a drain that flows into a creek that flows into Lake St.
Clair. A 4-foot-wide manmade berm separates the wetlands from the
ditch; thus water rarely if ever passes from wetlands to ditch or
vice versa. Petitioners applied for a
permit to fill most of these wetlands with 57,500 cubic yards of
material. They intended to build a 112-unit condominium development
on the site. After inspecting the site and considering comments
from, among others, the Water Quality Unit of the Macomb County
Prosecutor’s Office (which urged the Corps to deny the permit
because “[t]he loss of this high quality wetland area would have an
unacceptable adverse effect on wildlife, water quality, and
conservation of wetlands resources,” App. in No. 04–1384, p. 79a),
the Corps denied the permit. Id., at 84a–126a. As
summarized in a letter sent to petitioners, reasons for denial
included: “Your parcel is primarily a
forested wetland that provides valuable seasonal habitat for
aquatic organisms and year round habitat for terrestrial organisms.
Additionally, the site provides water storage functions that, if
destroyed, could result in an increased risk of erosion and
degradation of water quality in the Sutherland-Oemig Drain, Auvase
Creek, and Lake St. Clair. The minimization of impacts to these
wetlands is important for conservation and the overall ecology of
the region. Because the project development area is a forested
wetland, the proposed project would destroy the resources in such a
manner that they would not soon recover from impacts of the
discharges. The extent of impacts in the project area when
considered both individually and cumulatively would be unacceptable
and contrary to the public interest.” Id., at
127a–128a. As in No. 04–1034, the unanimous
judgment of the District and Circuit Judges was that the Corps has
jurisdiction over this wetland because it is adjacent to a
tributary of traditionally navigable waters. 391 F. 3d 704
(CA6 2004). The Solicitor General defends both
judgments. II Our unanimous
opinion in Riverside Bayview squarely controls these
cases. There, we evaluated the validity of the very same
regulations at issue today. These regulations interpret “waters of
the United States” to cover all traditionally navigable waters;
tributaries of these waters; and wetlands adjacent to traditionally
navigable waters or their tributaries. 33 CFR §§328.3(a)(1), (5),
and (7) (2005); §§323.2(a)(1), (5), and (7) (1985). Although the
particular wetland at issue in Riverside Bayview abutted a
navigable creek, we framed the question presented as whether the
Clean Water Act “authorizes the Corps to require landowners to
obtain permits from the Corps before discharging fill material into
wetlands adjacent to navigable bodies of water and their
tributaries .” 474 U. S., at 123 (emphasis added).[ Footnote 3 ] We held that,
pursuant to our decision in Chevron , “our review is limited to the
question whether it is reasonable, in light of the language,
policies, and legislative history of the Act for the Corps to
exercise jurisdiction over wetlands adjacent to but not regularly
flooded by rivers, streams, and other hydrographic features more
conventionally identifiable as ‘waters.’ ” 474 U. S., at
131. Applying this
standard, we held that the Corps’ decision to interpret “waters of
the United States” as encompassing such wetlands was permissible.
We recognized the practical difficulties in drawing clean lines
between land and water, id., at 132, and deferred to the
Corps’ judgment that treating adjacent wetlands as “waters” would
advance the “congressional concern for protection of water quality
and aquatic ecosystems,” id., at 133. Contrary to the plurality’s
revisionist reading today, ante , at 21–24, 28–29, Riverside Bayview nowhere implied that our approval of
“adjacent” wetlands was contingent upon an understanding that
“adjacent” means having a “continuous surface connection” between
the wetland and its neighboring creek, ante, at 23.
Instead, we acknowledged that the Corps defined “adjacent” as
including wetlands “ ‘that form the border of or are in
reasonable proximity to other waters’ ” and found that the
Corps reasonably concluded that adjacent wetlands are part of the
waters of the United States. 474 U. S., at 134 (quoting 42 Fed.
Reg. 37128 (1977)). Indeed, we explicitly acknowledged that the
Corps’ jurisdictional determination was reasonable even
though “not every adjacent wetland is of
great importance to the environment of adjoining bodies of water. .
. . If it is reasonable for the Corps to conclude that in the
majority of cases, adjacent wetlands have significant effects on
water quality and the ecosystem, its definition can stand. That the
definition may include some wetlands that are not significantly
intertwined with the ecosystem of adjacent waterways is of little
moment, for where it appears that a wetland covered by the Corps’
definition is in fact lacking in importance to the aquatic
environment . . . the Corps may always allow development of the
wetland for other uses simply by issuing a permit.” 474 U. S., at
135, n. 9. In closing, we emphasized that the
scope of the Corps’ asserted jurisdiction over wetlands had been
specifically brought to Congress’ attention in 1977, that Congress
had rejected an amendment that would have narrowed that
jurisdiction, and that even proponents of the amendment would not
have removed wetlands altogether from the definition of “waters of
the United States.” Id., at 135–139. Disregarding the importance of Riverside Bayview , the plurality relies heavily on the
Court’s subsequent opinion in Solid Waste Agency of Northern
Cook Cty. v. Army Corps of Engineers, 531 U. S. 159 (2001) (SWANCC) . In stark contrast to Riverside Bayview ,
however, SWANCC had nothing to say about wetlands, let
alone about wetlands adjacent to traditionally navigable waters or
their tributaries. Instead, SWANCC dealt with a question
specifically reserved by Riverside Bayview, see n. 3, supra , namely, the Corps’ jurisdiction over isolated
waters—“ ‘waters that are not part of a tributary
system to interstate waters or to navigable waters of the United
States, the degradation or destruction of which could affect
interstate commerce.’ ” 531 U. S., at 168–169 (quoting 33 CFR
§323.2(a)(5) (1978); emphasis added); see also 531 U. S., at 163
(citing 33 CFR §328.2(a)(3) (1999), which is the later regulatory
equivalent to §323.2(a)(5) (1978)). At issue in SWANCC was
“an abandoned sand and gravel pit . . . which provide[d] habitat
for migratory birds” and contained a few pools of “nonnavigable,
isolated, intrastate waters.” 531 U. S., at 162, 166. The Corps had
asserted jurisdiction over the gravel pit under its 1986 Migratory
Bird Rule, which treated isolated waters as within its jurisdiction
if migratory birds depended upon these waters. The Court rejected
this jurisdictional basis since these isolated pools, unlike the
wetlands at issue in Riverside Bayview , had no
“significant nexus” to traditionally navigable waters. 531 U. S.,
at 167. In the process, the Court distinguished Riverside
Bayview ’s reliance on Congress’ decision to leave the Corps’
regulations alone when it amended the Act in 1977, since
“ ‘[i]n both Chambers, debate on the proposals to narrow the
definition of navigable waters centered largely on the issue of
wetlands preservation’ ” rather than on the Corps’
jurisdiction over truly isolated waters. 531 U. S., at 170 (quoting
474 U. S., at 136).[ Footnote
4 ] Unlike SWANCC and
like Riverside Bayview, the cases before us today concern
wetlands that are adjacent to “navigable bodies of water [or] their
tributaries,” 474 U. S., at 123. Specifically, these wetlands abut
tributaries of traditionally navigable waters. As we recognized in Riverside Bayview , the Corps has concluded that such
wetlands play important roles in maintaining the quality of their
adjacent waters, see id., at 134–135, and consequently in
the waters downstream. Among other things, wetlands can offer
“nesting, spawning, rearing and resting sites for aquatic or land
species”; “serve as valuable storage areas for storm and flood
waters”; and provide “significant water purification functions.” 33
CFR §320.4(b)(2) (2005); 474 U. S., at 134–135. These values are
hardly “ independent ” ecological considerations as the
plurality would have it, ante, at 23—instead, they are
integral to the “chemical, physical, and biological integrity of
the Nation’s waters,” 33 U. S. C. §1251(a). Given that
wetlands serve these important water quality roles and given the
ambiguity inherent in the phrase “waters of the United States,” the
Corps has reasonably interpreted its jurisdiction to cover
non-isolated wetlands. See 474 U. S., at 131–135.[ Footnote 5 ] This conclusion is further
confirmed by Congress’ deliberate acquiescence in the Corps’
regulations in 1977. Id., at 136. Both Chambers conducted
extensive debates about the Corps’ regulatory jurisdiction over
wetlands, rejected efforts to limit this jurisdiction, and
appropriated funds for a “ ‘National Wetlands
Inventory’ ” to help the States “ ‘in the development and
operation of programs under this Act.’ ” Id., at
135–139 (quoting 33 U. S. C. §1288(i)(2)). We found these
facts significant in Riverside Bayview , see 474 U. S., at
135–139, as we acknowledged in SWANCC . See 531 U. S., at
170–171 (noting that “ [b]eyond Congress’ desire to regulate
wetlands adjacent to ‘navigable waters,’ respondents point us
to no persuasive evidence” of congressional acquiescence (emphasis
added)). The Corps’ exercise of
jurisdiction is reasonable even though not every wetland adjacent
to a traditionally navigable water or its tributary will perform
all (or perhaps any) of the water quality functions generally
associated with wetlands. Riverside Bayview made clear
that jurisdiction does not depend on a wetland-by-wetland inquiry.
474 U. S., at 135, n. 9. Instead, it is enough that wetlands
adjacent to tributaries generally have a significant nexus to the
watershed’s water quality. If a particular wetland is “not
significantly intertwined with the ecosystem of adjacent
waterways,” then the Corps may allow its development “simply by
issuing a permit.” Ibid.[ Footnote 6 ] Accordingly, for purposes of the Corps’
jurisdiction it is of no significance that the wetlands in No.
04–1034 serve flood control and sediment sink functions, but may
not do much to trap other pollutants, supra, at 4–5, and
n. 2, or that the wetland in No. 04–1328 keeps excess water
from Lake St. Clair but may not trap sediment, see supra ,
at 5–6. Seemingly alarmed by the costs
involved, the plurality shies away from Riverside
Bayview ’s recognition that jurisdiction is not a case-by-case
affair. I do not agree with the plurality’s assumption that the
costs of preserving wetlands are unduly high. It is true that the
cost of §404 permits are high for those who must obtain
them[ Footnote 7 ]—but these
costs amount to only a small fraction of 1% of the $760 billion
spent each year on private and public construction and development
activity. Sunding & Zilberman 80. More significant than the
plurality’s exaggerated concern about costs, however, is the fact
that its omission of any discussion of the benefits that the
regulations at issue have produced sheds a revelatory light on the
quality (and indeed the impartiality) of its cost-benefit
analysis.[ Footnote 8 ] The
importance of wetlands for water quality is hard to overstate. See, e.g., U. S. Congress, Office of Technology Assessment,
Wetlands: Their Use and Regulation, OTA–206, pp. 43–61 (Mar. 1984),
http://govinfo.library.unt.edu/ota/Ota_4/DATA/1984/8433.PDF
(hereinafter OTA) (describing wetlands’ role in floodpeak
reduction, shoreline protection, ground water recharge, trapping of
suspended sediment, filtering of toxic pollutants, and protection
of fish and wildlife). See also ante , at 20 (Kennedy, J.,
concurring in judgment). Unsurprisingly, the Corps’ approach has
the overwhelming endorsement of numerous amici curiae ,
including 33 States and the county in which the property in No.
04–1384 is located. In final analysis, however,
concerns about the appropriateness of the Corps’ 30-year
implementation of the Clean Water Act should be addressed to
Congress or the Corps rather than to the Judiciary. Whether the
benefits of particular conservation measures outweigh their costs
is a classic question of public policy that should not be answered
by appointed judges. The fact that large investments are required
to finance large developments merely means that those who are most
adversely affected by the Corps’ permitting decisions are persons
who have the ability to communicate effectively with their
representatives. Unless and until they succeed in convincing
Congress (or the Corps) that clean water is less important today
than it was in the 1970’s, we continue to owe deference to
regulations satisfying the “evident breadth of congressional
concern for protection of water quality and aquatic ecosystems”
that all of the Justices on the Court in 1985 recognized in Riverside Bayview, 474 U. S., at 133. III Even setting
aside the plurality’s dramatic departure from our reasoning and
holding in Riverside Bayview , its creative opinion is
utterly unpersuasive. The plurality imposes two novel conditions on
the exercise of the Corps’ jurisdiction that can only muddy the
jurisdictional waters. As Justice Kennedy observes, “these
limitations . . . are without support in the language and purposes
of the Act or in our cases interpreting it.” Ante, at 11
(opinion concurring in judgment). The impropriety of crafting these
new conditions is highlighted by the fact that no party or amicus has suggested either of them.[ Footnote 9 ] First, ignoring
the importance of preserving jurisdiction over water beds that are
periodically dry, the plurality imposes a requirement that only
tributaries with the “relatively permanent” presence of water fall
within the Corps’ jurisdiction. Ante, at 13–14. Under the
plurality’s view, then, the Corps can regulate polluters who dump
dredge into a stream that flows year round but may not be able to
regulate polluters who dump into a neighboring stream that flows
for only 290 days of the year—even if the dredge in this second
stream would have the same effect on downstream waters as the
dredge in the year-round one. Ante, at 14,
n. 5.[ Footnote
10 ] To find this arbitrary
distinction compelled by the statute, the plurality cites a
dictionary for a proposition that it does not contain. The
dictionary treats “streams” as “waters” but has nothing to say
about whether streams must contain water year round to qualify as
“streams.” Ante, at 13–14, and n. 6 (citing Webster’s
New International Dictionary 2493 (2d ed. 1954) (hereinafter
Webster’s Second), as defining stream as a “ ‘current or
course of water or other fluid, flowing on the earth’ ”). From
this, the plurality somehow deduces that streams can never be
intermittent or ephemeral ( i.e., flowing for only part of
the year). Ante , at 13–15, and nn. 5–6. But common
sense and common usage demonstrate that intermit- tent streams,
like perennial streams, are still streams.[ Footnote 11 ] See, e.g., U. S. Dept. of
Interior, U. S. Geological Survey, Topographic Map Symbols 3
(2005), http://erg.usgs.gov/isb/pubs/booklets/symbols/ (identifying
symbols for “[p]erennial stream” and “[i]ntermittent stream,” as
well as for “[p]erennial river” and “[i]ntermittent river”). This
was true well before the passage of the Act in 1972. E.g., Webster’s Third New International Dictionary 1180 (1961)
(hereinafter Webster’s Third) (linking “intermittent” with
“stream”). Indeed, we ourselves have used the term “intermittent
stream” as far back as 1932. Harrisonville v. W. S.
Dickey Clay Mfg. Co., 289 U. S. 334 , 335
(1933). Needless to say, Justice Brandeis’ use of the term in a
unanimous opinion should not be dismissed as merely a “useful
oxymor[on],” ante, at 15, n. 6 (plurality
opinion). The plurality attempts to
bolster its arbitrary jurisdictional line by citing two tangential
statutory provisions and two inapplicable canons of construction.
None comes close to showing that Congress directly spoke to whether
“waters” requires the relatively permanent presence of
water. The first provision relied on
by the plurality—the definition of “point source” in 33 U.
S. C. §1362(14)—has no conceivable bearing on whether
permanent tributaries should be treated differently from
intermittent ones, since “pipe[s], ditch[es], channel[s],
tunnel[s], conduit[s], [and] well[s]” can all hold water
permanently as well as intermittently.[ Footnote 12 ] The second provision is §1251(b), which
announces a congressional policy to “recognize, preserve, and
protect the primary responsibilities and rights of States” to
prevent pollution, to plan development, and to consult with the
EPA. Under statutory additions made in 1977 when Congress
considered and declined to alter the Corps’ interpretation of its
broad regulatory jurisdiction, the States may run their own §404
programs. §§1344(g)–(h). As modified, §1251(b) specifically
recognizes this role for the States as part of their primary
responsibility for preventing water pollution. Even focusing only
on the Act as it stood between 1972 and 1977, but see International Paper Co. v. Ouellette, 479 U. S. 481 , 489–490
(1987) (interpreting §1251(b) in light of the 1977 additions),
broad exercise of jurisdiction by the Corps still left the States
with ample rights and responsibilities. See S. D. Warren
Co. v. Maine Bd. of Environmental Protection , 547 U.
S. __, __ (2006) (slip op., at 14–15). States had the power to
impose tougher water pollution standards than required by the Act,
§1370, and to prevent the Corps and the EPA from issuing permits,
§1341(a)(1)—not to mention nearly exclusive responsibility for
containing pollution from nonpoint sources. The two canons of construction
relied on by the plurality similarly fail to overcome the deference
owed to the Corps. First, the plurality claims that concerns about
intruding on state power to regulate land use compel the conclusion
that the phrase “waters of the United States” does not cover
intermittent streams. As we have recognized, however, Congress
found it “ ‘essential that discharge of pollutants be
controlled at the source,’ ” Riverside Bayview, 474
U. S., at 133 (quoting S. Rep. No. 92–414, p. 77 (1972)), and
the Corps can define “waters” broadly to accomplish this aim.
Second, the plurality suggests that the canon of constitutional
avoidance applies because the Corps’ approach might exceed the
limits of our Commerce Clause authority. Setting aside whether such
a concern was proper in SWANCC , 531 U. S., at 173; but see id., at 192–196 (Stevens, J., dissenting), it is plainly
not warranted here. The wetlands in these cases are not “isolated”
but instead are adjacent to tributaries of traditionally navigable
waters and play important roles in the watershed, such as keeping
water out of the tributaries or absorbing water from the
tributaries. “There is no constitutional reason why Congress
cannot, under the commerce power, treat the watersheds as a key to
flood control on navigable streams and their tributaries.” Oklahoma ex rel. Phillips v. Guy F. Atkinson
Co., 313 U. S.
508 , 525 (1941). Most importantly, the
plurality disregards the fundamental significance of the Clean
Water Act. As then-Justice Rehnquist explained when writing for the
Court in 1981, the Act was “not merely another law” but rather was
“viewed by Congress as a ‘total restructuring’ and ‘complete
rewriting’ of the existing water pollution legislation.” Milwaukee v. Illinois, 451 U. S. 304 , 317.
“Congress’ intent in enacting the [Act] was clearly to establish an
all-encompassing program of water pollution regulation,” and “the
most casual perusal of the legislative history demonstrates that .
. . views on the comprehensive nature of the legislation were
practically universal.” Id., at 318, and n. 12; see
also 531 U. S., at 177–181 (Stevens, J., dissenting). The Corps has
concluded that it must regulate pollutants at the time they enter
ditches or streams with ordinary high-water marks—whether
perennial, intermittent, or ephemeral—in order to properly control
water pollution. 65 Fed. Reg. 12823 (2000). Because there is
ambiguity in the phrase “waters of the United States” and because
interpreting it broadly to cover such ditches and streams advances
the purpose of the Act, the Corps’ approach should command our
deference . Intermittent streams can carry pollutants just
as perennial streams can, and their regulation may prove as
important for flood control purposes. The inclusion of all
identifiable tributaries that ultimately drain into large bodies of
water within the mantle of federal protection is surely
wise. The plurality’s second
statutory invention is as arbitrary as its first. Trivializing the
significance of changing conditions in wetlands environments, the
plurality imposes a separate requirement that “the wetland has a
continuous surface connection” with its abutting waterway such that
it is “difficult to determine where the ‘water’ ends and the
‘wetland’ begins.” Ante, at 24. An “intermittent,
physically remote hydrologic connection” between the wetland and
other waters is not enough. Ibid. Under this view,
wetlands that border traditionally navigable waters or their
tributaries and perform the essential function of soaking up
overflow waters during hurricane season—thus reducing flooding
downstream—can be filled in by developers with impunity, as long as
the wetlands lack a surface connection with the adjacent waterway
the rest of the year. The plurality begins
reasonably enough by recognizing that the Corps may appropriately
regulate all wetlands “ ‘adjacent to’ ” other waters. Ante, at 21. This recognition is wise, since the statutory
text clearly accepts this standard. Title 33 U. S. C.
§1344(g)(1), added in 1977, includes “adjacent wetlands” in its
description of “waters” and thus “expressly stated that the term
‘waters’ included adjacent wetlands.” Riverside Bayview, 474 U. S., at 138. While this may not “conclusively determine the
construction to be placed on the use of the term ‘waters’ elsewhere
in the Act . . . , in light of the fact that the various provisions
of the Act should be read in pari materia , it does at
least suggest strongly that the term ‘waters’ as used in the Act
does not necessarily exclude ‘wetlands.’ ” Id., at
138, n. 11. The plurality goes on,
however, to define “ ‘adjacent to’ ” as meaning “with a
continuous surface connection to” other water. Ante, at
21–24. It is unclear how the plurality reached this conclusion,
though it plainly neglected to consult a dictionary. Even its
preferred Webster’s Second defines the term as “[l]ying near,
close, or contiguous; neighboring; bordering on” and
acknowledges that “[o]bjects are Adjacent when they lie close to
each other, but not necessarily in actual contact. ”
Webster’s Second 32 (emphasis added); see also Webster’s Third 26.
In any event, the proper question is not how the plurality would
define “adjacent,” but whether the Corps’ definition is
reasonable. The Corps defines “adjacent”
as “bordering, contiguous, or neighboring,” and specifies that
“[w]etlands separated from other waters of the United States by
man-made dikes or barriers, natural river berms, beach dunes and
the like are ‘adjacent wetlands.’ ” 33 CFR §328.3(c) (2005).
This definition is plainly reasonable, both on its face and in
terms of the purposes of the Act. While wetlands that are
physically separated from other waters may perform less valuable
functions, this is a matter for the Corps to evaluate in its
permitting decisions. We made this clear in Riverside
Bayview , 474 U. S., at 135, n. 9—which did not impose the
plurality’s new requirement despite an absence of evidence that the
wetland at issue had the sort of continuous surface connection
required by the plurality today. See supra , at 7; see also ante, at 15–17 (Kennedy, J., concurring in judgment)
(observing that the plurality’s requirement is inconsistent with Riverside Bayview ). And as the facts of No. 04–1384
demonstrate, wetland separated by a berm from adjacent tributaries
may still prove important to downstream water quality. Moreover,
Congress was on notice of the Corps’ definition of “adjacent” when
it amended the Act in 1977 and added 33 U. S. C. §1344(g)(1).
See 42 Fed. Reg. 37129 (1977). Finally, implicitly
recognizing that its approach endangers the quality of waters which
Congress sought to protect, the plurality suggests that the EPA can
regulate pollutants before they actually enter the “waters of the
United States.” Ante, at 24–27. I express no view on the
merits of the plurality’s reasoning, which relies heavily on a
respect for lower court judgments that is conspicuously lacking
earlier in its opinion, ante, at 8–10. I do fail to understand,
however, why the plurality would not similarly apply this logic to
dredged and fill material. The EPA’s authority over pollutants
(other than dredged and fill materials) stems from the identical
statutory language that gives rise to the Corps’ §404 jurisdiction.
The plurality claims that there is a practical difference,
asserting that dredged and fill material “does not normally wash
downstream.” Ante, at 26. While more of this material will
probably stay put than is true of soluble pollutants, the very
existence of words like “alluvium” and “silt” in our language, see
Webster’s Third 59, 2119, suggests that at least some fill makes
its way downstream. See also, e.g., United States v. Deaton, 332 F. 3d 698, 707 (CA4 2003) (“Any
pollutant or fill material that degrades water quality in a
tributary has the potential to move downstream and degrade the
quality of the navigable waters themselves”). Moreover,
such fill can harm the biological integrity of downstream waters
even if it largely stays put upstream. The Act’s purpose of
protecting fish, see 33 U. S. C. §1251(a)(2); S. D.
Warren Co., 547 U. S., at __ (slip op., at 13–14), could be
seriously impaired by sediment in upstream waters where fish spawn,
since excessive sediment can “smother bottom-dwelling invertebrates
and impair fish spawning,” OTA 48. See also, e.g., Erman
& Hawthorne, The Quantitative Importance of an Intermittent
Stream in the Spawning of Rainbow Trout, 105 Transactions of the
American Fisheries Society 675–681 (1976); Brief for American
Rivers et al. as Amici Curiae 14 (observing that
anadromous salmon often spawn in small, intermittent
streams). IV While
I generally agree with Parts I and II–A of Justice Kennedy’s
opinion, I do not share his view that we should replace regulatory
standards that have been in place for over 30 years with a
judicially crafted rule distilled from the term “significant nexus”
as used in SWANCC. To the extent that our passing use of
this term has become a statutory requirement, it is categorically
satisfied as to wetlands adjacent to navigable waters or their
tributaries. Riverside Bayview and SWANCC together make this clear. SWANCC’ s only use of the term
comes in the sentence: “It was the significant nexus between the
wetlands and ‘navigable waters’ that informed our reading of the
[Clean Water Act] in Riverside Bayview .” 531 U. S., at
167. Because Riverside Bayview was written to encompass
“wetlands adjacent to navigable waters and their tributaries,” 474
U. S., at 123, and reserved only the question of isolated waters,
see id., at 131–132, n. 8; see also n. 3, supra , its determination of the Corps’ jurisdiction
applies to the wetlands at issue in these cases. Even
setting aside the apparent applicability of Riverside
Bayview . I think it clear that wetlands adjacent to
tributaries of navigable waters generally have a “significant
nexus” with the traditionally navigable waters downstream. Unlike
the “nonnavigable, isolated, intrastate waters” in SWANCC ,
531 U. S., at 171, these wetlands can obviously have a cumulative
effect on downstream water flow by releasing waters at times of low
flow or by keeping waters back at times of high flow. This logical
connection alone gives the wetlands the “limited” connection to
traditionally navigable waters that is all the statute requires,
see id., at 172; 474 U. S., at 133—and disproves Justice
Kennedy’s claim that my approach gives no meaning to the word
“ ‘ navigable,’ ” ante, at 21 (opinion
concurring in judgment). Similarly, these wetlands can preserve
downstream water quality by trapping sediment, filtering toxic
pollutants, protecting fish-spawning grounds, and so forth. While
there may exist categories of wetlands adjacent to tributaries of
traditionally navigable waters that, taken cumulatively, have no
plausibly discernable relationship to any aspect of downstream
water quality, I am skeptical. And even given Justice Kennedy’s
“significant nexus” test, in the absence of compelling evidence
that many such categories do exist I see no reason to conclude that
the Corps’ longstanding regulations are
overbroad. Justice Kennedy’s
“significant nexus” test will probably not do much to diminish the
number of wetlands covered by the Act in the long run. Justice
Kennedy himself recognizes that the records in both cases contain
evidence that “should permit the establishment of a significant
nexus,” ante, at 27, see also ante, at 26, and it
seems likely that evidence would support similar findings as to
most (if not all) wetlands adjacent to tributaries of navigable
waters. But Justice Kennedy’s approach will have the effect of
creating additional work for all concerned parties. Developers
wishing to fill wetlands adjacent to ephemeral or intermittent
tributaries of traditionally navigable waters will have no certain
way of knowing whether they need to get §404 permits or not. And
the Corps will have to make case-by-case (or category-by-category)
jurisdictional determinations, which will inevitably increase the
time and resources spent processing permit applications. These
problems are precisely the ones that Riverside Bayview ’s
deferential approach avoided. See 474 U. S., at 135, n. 9
(noting that it “is of little moment” if the Corps’ jurisdiction
encompasses some wetlands “not significantly intertwined” with
other waters of the United States). Unlike Justice Kennedy, I see
no reason to change Riverside Bayview ’s approach—and every
reason to continue to defer to the Executive’s sensible,
bright-line rule. V As I
explained in SWANCC , Congress passed the Clean Water Act
in response to wide-spread recognition—based on events like the
1969 burning of the Cuyahoga River in Cleveland—that our waters had
become appallingly polluted. 531 U. S., at 174–175 (dissenting
opinion). The Act has largely succeeded in restoring the quality of
our Nation’s waters. Where the Cuyahoga River was once coated with
industrial waste, “[t]oday, that loca- tion is lined with
restaurants and pleasure boat slips.” EPA, A Benefits Assessment of
the Water Pollution Control Programs Since 1972, p. 1–2 (Jan.
2000), http://www.epa.gov/ost/economics/assessment.pdf. By
curtailing the Corps’ jurisdiction of more than 30 years, the
plurality needlessly jeopardizes the quality of our waters. In
doing so, the plurality disregards the deference it owes the
Executive, the congressional acquiescence in the Executive’s
position that we recognized in Riverside Bayview , and its
own obligation to interpret laws rather than to make them. While
Justice Kennedy’s approach has far fewer faults, nonetheless it
also fails to give proper deference to the agencies entrusted by
Congress to implement the Clean Water Act. I
would affirm the judgments in both cases, and respectfully dissent
from the decision of five Members of this Court to vacate and
remand. I close, however, by noting an unusual feature of the
Court’s judgments in these cases. It has been our practice in a
case coming to us from a lower federal court to enter a judgment
commanding that court to conduct any further proceedings pursuant
to a specific mandate. That prior practice has, on occasion, made
it necessary for Justices to join a judgment that did not conform
to their own views.[ Footnote
13 ] In these cases, however, while both the plurality and
Justice Kennedy agree that there must be a remand for further
proceedings, their respective opinions define different tests to be
applied on remand. Given that all four Justices who have joined
this opinion would uphold the Corps’ jurisdiction in both of these
cases—and in all other cases in which either the plurality’s or
Justice Kennedy’s test is satisfied—on remand each of the judgments
should be reinstated if either of those tests is
met.[ Footnote
14 ] Footnote 1 Pursuant to 33 U.
S. C. §§1344(g)–(h), Michigan operates its own §404 permitting
program, subject to supervision from the Army
Corps. Footnote 2 Dr. Willard did
not “stud[y] the upstream drainage of these sites . . . well enough
to make a statement” about whether they also performed
pollutant-trapping functions. 4 Tr. 96. Footnote 3 By contrast, we
“d[id] not express any opinion” on the Corps’ additional assertion
of jurisdiction over “wetlands that are not adjacent to bodies of
open water, see 33 CFR §323.2(a)(2) and (3) (1985).” 474 U. S., at
131–132, n. 8; see also id., at 124, n. 2
(making the same reservation). Contrary to Justice Kennedy’s
reading, ante, at 23–24 (opinion concurring in judgment),
we were not reserving the issue of the Corps’ jurisdiction over
wetlands adjacent to tributaries, but only reserving the issue of
the Corps’ jurisdiction over truly isolated waters. A glance at the
cited regulation makes this clear. Section 323.2(a)(2) refers to
“[a]ll interstate waters including interstate wetlands” and
§323.2(a)(3) covers “[a]ll other waters such as intrastate lakes,
rivers, streams (including intermittent streams), mudflats,
sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa
lakes, or natural ponds, the use, degradation or destruction of
which could affect interstate or foreign commerce including any
such waters.” See also Solid Waste Agency of Northern Cook
Cty. v. Army Corps of Engineers, 531 U. S. 159 , 163–164 (2001)
(considering the validity of an application of §328.3(a)(3) (1999),
which is substantively identical to §323.2(a)(3) (1985) and to
§323.2(a)(5) (1978)). Wetlands adjacent to tributaries of
traditionally navigable waters were covered in the 1985 regulation
by other provisions of the regulation, namely a combination of
§§323.2(a)(1) (covering traditionally navigable waters), (4)
(covering tributaries of subsection (a)(1) waters), and (7)
(covering wetlands adjacent to subsection (a)(4)
waters). Footnote 4 As The Chief
Justice observes, the Corps and the EPA initially considered
revising their regulations in response to SWANCC . Ante, at 1–2 (concurring opinion). The Chief Justice
neglects to mention, however, that almost all of the 43 States to
submit comments opposed any significant narrowing of the Corps’
jurisdiction—as did roughly 99% of the 133,000 other comment
submitters. See U. S. General Accounting Office, Report to the
Chairman, Subcommittee on Energy Policy, Natural Resources and
Regulating Affairs, Committee on Government Reform, House of
Representatives, Waters and Wetlands: Corps of Engineers Needs to
Evaluate Its District Office Practices in Determining Jurisdiction,
GAO–04–297, pp. 14–15 (Feb. 2004),
http://www.gao.gov/new.items/d04297.pdf (hereinafter GAO Report)
(all Internet materials as visited June 14, 2006, and available in
Clerk of Court’s case file); Brief for Association of State and
Interstate Water Pollution Control Administrators as Amicus
Curiae . In any event, the agencies’ decision to abandon their
rulemaking is hardly responsible for the cases at hand. The
proposed rulemaking focused on isolated waters, which are covered
by 33 CFR §328.3(a)(3) (1999) and which were called into question
by SWANCC , rather than on wetlands adjacent to tributaries
of navigable waters, which are covered by a combination of
§§328.3(a)(1), (5), and (7) and which (until now) seemed obviously
within the agencies’ jurisdiction in light of Riverside
Bayview . See 68 Fed. Reg. 1994 (2003) (“The agencies seek
comment on the use of the factors in 33 CFR 328.3(a)(3)(i)–(iii) .
. . in determining [Clean Water Act] jurisdiction over isolated,
intrastate, non-navigable waters”). Footnote 5 Unsurprisingly,
most Courts of Appeals to consider the scope of the Corps’
jurisdiction after SWANCC have unhesitatingly concluded
that this jurisdiction covers intermittent tributaries and wetlands
adjacent—in the normal sense of the word—to traditionally navigable
waters and their tributaries. E.g., United States v. Deaton , 332 F. 3d 698 (CA4 2003) (upholding the
Corps’ jurisdiction over wetlands adjacent to a ditch that might
not contain consistently flowing water but did drain into another
ditch that drained into a creek that drained into a navigable
waterway); Headwaters, Inc. v. Talent Irrigation
Dist., 243 F. 3d 526 (CA9 2001) (treating as “waters of
the United States” canals that held water intermittently and
connected to other tributaries of navigable waters); United
States v. Rueth Development Co., 335 F. 3d 598,
604 (CA7 2003) (observing “it is clear that SWANCC did not
affect the law regarding . . . adjacency” in upholding the Corps’
jurisdiction over a wetland without finding that this wetland had a
continuous surface connection to its adjacent tributary); Baccarat Fremont v. U. S. Army Corps of
Engineers, 425 F. 3d 1150, 1156 (CA9 2005) (upholding the
Corps’ jurisdiction over wetlands separated by berms from
traditionally navigable channels and observing that
“ SWANCC simply did not address the issue of jurisdiction
over adjacent wetlands”); but see In re Needham , 354
F. 3d 340 (CA5 2003) (reading “waters of the United States”
narrowly as used in the Oil Pollution Act of
1990). Footnote 6 Indeed, “[t]he
Corps approves virtually all section 404 permit[s],” though often
requiring applicants to avoid or mitigate impacts to wetlands and
other waters. GAO Report 8. Footnote 7 According to the
Sunding and Zilberman article cited by the plurality, ante, at 2, for 80% of permits the mean cost is about
$29,000 (with a median cost of about $12,000). The Economics of
Environmental Regulation by Licensing: An Assessment of Recent
Changes to the Wetland Permitting Process, 42 Natural Resources J.
59, 63, 74 (2002) (hereinafter Sunding & Zilberman). Only for
less than 20% of the permits—those for projects with the most
significant impacts on wetlands—is the mean cost around $272,000
(and the median cost is $155,000). Ibid. Of course, not
every placement of fill or dredged material into the waters of the
United States requires a §404 permit. Only when such fill comes
from point sources—“discernible, confined and discrete
conveyance[s]”—is a §404 permit needed. 33 U. S. C. §§1362(12),
(14). Moreover, permits are not required for discharges from point
sources engaged in, among other things, normal farming activities;
maintenance of transportation structures; and construction of
irrigation ditches, farm roads, forest roads, and temporary mining
roads. §1344(f). Footnote 8 Rather than
defending its own antagonism to environmentalism, the plurality
counters by claiming that my dissent is “policy-laden.” Ante, at 28. The policy considerations that have influenced my thinking
are Congress’ rather than my own. In considering whether the Corps’
interpretation of its jurisdiction is reasonable, I am admittedly
taking into account the congressional purpose of protecting the
physical, chemical, and biological integrity of our waters. See 33
U. S. C. §1251(a); see also Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 863 , 837
(1984) (considering whether the agency regulation was consistent
with “the policy concerns that motivated the [Clean Air Act’s]
enactment”). Footnote 9 Only 3 of the 21 amici briefs filed on petitioners’ behalf come even close
to asking for one of the plurality’s two conditions. These briefs
half-argue that intermittent streams should fall outside the Corps’
jurisdiction—though not for the reasons given by the plurality. See
Brief for National Stone, Sand and Gravel Assn. et al. 20,
n. 7; Brief for Foundation for Environmental and Economic
Progress et al. 22–23; Brief for Western Coalition of Arid
States 10. Footnote 10 The plurality
does suggest that “ seasonal rivers” are not “necessarily
exclude[d]” from the Corps’ jurisdiction—and then further suggests
that “streams” are “rivers.” Ante, at 14, n. 5. I
will not explore the semantic issues posed by the latter point. On
the former point, I have difficulty understanding how a “seasonal”
river could meet the plurality’s test of having water present
“relatively permanent[ly].” By failing to explain itself, the
plurality leaves litigants without guidance as to where the line it
draws between “relatively permanent” and “intermittent”
lies. Footnote 11 Indeed, in the
1977 debate over whether to restrict the scope of the Corps’
regulatory power, Senator Bentsen recognized that the Corps’
jurisdiction “cover[s] all waters of the United States, including
small streams, ponds, isolated marshes, and intermittently flowing
gullies.” 4 Legislative History of the Clean Water Act of 1977
(Committee Print compiled for the Senate Committee on Environment
and Public Works by the Library of Congress), Ser. No. 95–14, p.
903 (1978). His proposed amendment to restrict this jurisdiction
failed. Id., at 947. Footnote 12 The plurality’s
reasoning to the contrary is mystifying. The plurality emphasizes
that a ditch around a castle is also called a “moat” and that a
navigable manmade channel is called a “canal.” See ante ,
at 17, n. 7. On their face (and even after much
head-scratching), these points have nothing to do with whether we
use the word “stream” rather than “ditch” where permanently present
water is concerned. Indeed, under the plurality’s reasoning, we
would call a “canal” a “stream” or a “river” rather than a
“canal.” Moreover, we do
use words like “ditch” without regard to whether water is present
relatively permanently. In Jennison v. Kirk, 98 U. S. 453 (1879), for example, Justice Field used the term “ditch”—not
“stream”—in describing a manmade structure that carried water year
round. See also, e.g., Knoxville Water Co. v. Knoxville, 200 U. S. 22 , 27 (1906)
(opinion for the Court by Harlan, J.) (describing “pipes” that
would continuously carry water); ante, at 20, 24
(plurality opinion) (using “channel” with reference to both
intermittent and relatively permanent waters); PUD No. 1 of
Jefferson Cty. v. Washington Dept. of Ecology, 511 U. S. 700 ,
709 (1994) (describing a “tunnel” that would carry water year
round); New Orleans Water-Works Co. v. Rivers, 115 U. S. 674 ,
683 (1885) (opinion for the Court by Harlan, J.) (describing
“conduits” that would supply water for a hotel). The plurality’s
attempt to achieve its desired outcome by redefining terms does no
credit to lexicography—let alone to justice. Footnote 13 See, e.g., Screws v. United States, 325 U. S. 91 , 131–134
(1945) (Rutledge, J., concurring in result); Turner
Broadcasting System, Inc. v. FCC, 512 U. S. 622 , 674
(1994) (Stevens, J., concurring in part and concurring in
judgment); Hamdi v. Rumsfeld, 542 U. S. 507 , 553–554
(2004) (Souter, J., concurring in part, dissenting in part, and
concurring in judgment). Footnote 14 I assume that
Justice Kennedy’s approach will be controlling in most cases
because it treats more of the Nation’s waters as within the Corps’
jurisdiction, but in the unlikely event that the plurality’s test
is met but Justice Kennedy’s is not, courts should also uphold the
Corps’ jurisdiction. In sum, in these and future cases the United
States may elect to prove jurisdiction under either
test. 547 U. S. ____ (2006) RAPANOS V. UNITED STATES 547 U. S. ____ (2006) SUPREME COURT OF THE UNITED STATES NOS. 04-1034 AND 04-1384 JOHN A. RAPANOS, et ux., et al.,
PETITIONERS

															04–1034 v. UNITED STATES JUNE CARABELL et al., PETITIONERS

															04–1384 v. UNITED STATES ARMY CORPS OF ENGINEERS
et al. on writs of certiorari to the united states
court of appeals for the sixth circuit [June 19, 2006] Justice Breyer ,
dissenting.

															   In my view, the authority of the
Army Corps of Engineers under the Clean Water Act extends to the
limits of congressional power to regulate interstate commerce. See Solid Waste Agency of Northern Cook Cty. v. Army Corps
of Engineers, 531 U. S. 159 , 181–182
(2001) ( SWANCC ) (Stevens, J., dissenting). I therefore
have no difficulty finding that the wetlands at issue in these
cases are within the Corps’ jurisdiction, and I join Justice
Stevens’ dissenting opinion.

															   My view of the statute rests in part upon the
nature of the problem. The statute seeks to “restore and maintain
the chemical, physical, and biological integrity of the Nation’s
waters.” 33 U. S. C. §1251(a). Those waters are so various and
so intricately interconnected that Congress might well have decided
the only way to achieve this goal is to write a statute that
defines “waters” broadly and to leave the enforcing agency with the
task of restricting the scope of that definition, either wholesale
through regulation or retail through development permissions. That
is why I believe that Congress, in using the term “waters of the
United States,” §1362(7), intended fully to exercise its relevant
Commerce Clause powers.

															   I mention this because the Court, contrary to
my view, has written a “nexus” requirement into the statute. SWANCC , supra , at 167; ante, at 22
(opinion of Kennedy, J.) (“[T]he Corps’ jurisdiction over wetlands
depends upon the existence of a significant nexus between the
wetlands in question and navigable waters in the traditional
sense”). But it has left the administrative powers of the Army
Corps of Engineers untouched. That agency may write regulations
defining the term—something that it has not yet done. And the
courts must give those regulations appropriate deference. Chevron U. S. A. Inc. v. Natural Resources
Defense Council, Inc., 467 U. S. 837 (1984).

															   If one thing is clear, it is that Congress
intended the Army Corps of Engineers to make the complex technical
judgments that lie at the heart of the present cases (subject to
deferential judicial review). In the absence of updated
regulations, courts will have to make ad hoc determinations
that run the risk of transforming scientific questions into matters
of law. That is not the system Congress intended. Hence I believe
that today’s opinions, taken together, call for the Army Corps of
Engineers to write new regulations, and speedily so.