RAPANOS et al. v. UNITED STATES

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715 OCTOBER TERM, 2005
Syllabus
RAPANOS et al. v. UNITED STATES
certiorari to the united states court of appeals for
the sixth circuit
No. 04–1034. Argued February 21, 2006—Decided June 19, 2006*
As relevant here, the Clean Water Act (CWA or Act) makes it unlawful to
discharge dredged or fill material into “navigable waters” without a per
mit, 33 U. S. C. §§ 1311(a), 1342(a), and defines “navigable waters” as
“the waters of the United States, including the territorial seas,”
§ 1362(7). The Army Corps of Engineers (Corps), which issues permits
for the discharge of dredged or fill material into navigable waters, inter
prets “the waters of the United States” expansively to include not only
traditional navigable waters, 33 CFR § 328.3(a)(1), but also other defined
waters, § 328.3(a)(2), (3); “[t]ributaries” of such waters, § 328.3(a)(5); and
wetlands “adjacent” to such waters and tributaries, § 328.3(a)(7). “[A]d
jacent” wetlands include those “bordering, contiguous [to], or neighbor
ing” waters of the United States even when they are “separated from
[such] waters . . . by man-made dikes . . . and the like.” § 328.3(c).
These cases involve four Michigan wetlands lying near ditches or
man-made drains that eventually empty into traditional navigable wa
ters. In No. 04–1034, the United States brought civil enforcement pro
ceedings against the Rapanos petitioners, who had backfilled three of
the areas without a permit. The District Court found federal jurisdic
tion over the wetlands because they were adjacent to “waters of the
United States” and held petitioners liable for CWA violations. Affirm
ing, the Sixth Circuit found federal jurisdiction based on the sites’ hy
drologic connections to the nearby ditches or drains, or to more remote
navigable waters. In No. 04–1384, the Carabell petitioners were denied
a permit to deposit fill in a wetland that was separated from a drainage
ditch by an impermeable berm. The Carabells sued, but the District
Court found federal jurisdiction over the site. Affirming, the Sixth Cir
cuit held that the wetland was adjacent to navigable waters.
Held: The judgments are vacated, and the cases are remanded.
No. 04–1034, 376 F. 3d 629, and No. 04–1384, 391 F. 3d 704, vacated and
remanded.
Justice Scalia, joined by The Chief Justice, Justice Thomas,
and Justice Alito, concluded:
*Together with No. 04–1384, Carabell et al. v. United States Army
Corps of Engineers et al., also on certiorari to the same court.

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1. 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,” Webster’s New International
Dictionary 2882 (2d ed.), and does not include channels through which
water flows intermittently or ephemerally, or channels that periodically
provide drainage for rainfall. The Corps’ expansive interpretation of
that phrase is thus not “based on a permissible construction of the stat
ute.” Chevron U. S. A. Inc. v. Natural Resources Defense Council,
Inc., 467 U. S. 837, 843. Pp. 730–739.
(a) While the meaning of “navigable waters” in the CWA is broader
than the traditional definition found in The Daniel Ball, 10 Wall. 557,
see Solid Waste Agency of Northern Cook Cty. v. Army Corps of Engi
neers, 531 U. S. 159, 167 (SWANCC); United States v. Riverside Bay
view Homes, Inc., 474 U. S. 121, 133, the CWA authorizes federal juris
diction only over “waters.” The use of the definite article “the” and
the plural number “waters” show plainly that § 1362(7) does not refer to
water in general, but more narrowly to water “[a]s found in streams,”
“oceans, rivers, [and] lakes,” Webster’s New International Dictionary
2882 (2d ed.). Those terms all connote relatively permanent bodies of
water, as opposed to ordinarily dry channels through which water occa
sionally or intermittently flows. Pp. 730–734.
(b) The Act’s use of the traditional phrase “navigable waters” fur
ther confirms that the CWA confers jurisdiction only over relatively
permanent bodies of water. Traditionally, such “waters” included only
discrete bodies of water, and the term still carries some of its original
substance, SWANCC, supra, at 172. This Court’s subsequent interpre
tation of “the waters of the United States” in the CWA likewise con
firms this limitation. See, e. g., Riverside Bayview, supra, at 131.
And the CWA itself categorizes the channels and conduits that typically
carry intermittent flows of water separately from “navigable waters,”
including them in the definition of “ ‘point sources,’ ” 33 U. S. C.
§ 1362(14). Moreover, only the foregoing definition of “waters” is con
sistent with the CWA’s stated policy “to recognize, preserve, and protect
the primary responsibilities and rights of the States . . . to plan the
development and use . . . of land and water resources . . . .” § 1251(b).
In addition, “the waters of the United States” hardly qualifies as the
clear and manifest statement from Congress needed to authorize intru
sion into such an area of traditional state authority as land-use regula
tion; and to authorize federal action that stretches the limits of Con
gress’s commerce power. See SWANCC, supra, at 173. Pp. 734–739.
2. A wetland may not be considered “adjacent to” remote “waters of
the United States” based on a mere hydrologic connection. Riverside

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Bayview rested on an inherent ambiguity in defining where the “water”
ends and its abutting (“adjacent”) wetlands begin, permitting the Corps
to rely on ecological considerations only to resolve that ambiguity in
favor of treating all abutting wetlands as waters. Isolated ponds are
not “waters of the United States” in their own right, see SWANCC,
supra, at 167, 171, and present no boundary-drawing problem justifying
the invocation of such ecological factors. Thus, 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 the two, are “adjacent” to such waters and covered by the
Act. Establishing coverage of the Rapanos and Carabell sites requires
finding that the adjacent channel contains a relatively permanent
“wate[r] of the United States,” and that each wetland has a continuous
surface connection to that water, making it difficult to determine where
the water ends and the wetland begins. Pp. 739–742.
3. Because the Sixth Circuit applied an incorrect standard to deter
mine whether the wetlands at issue are covered “waters,” and because
of the paucity of the record, the cases are remanded for further proceed
ings. P. 757.
Justice Kennedy concluded that the Sixth Circuit correctly recog
nized that a water or wetland constitutes “navigable waters” under the
Act if it possesses a “significant nexus” to waters that are navigable in
fact or that could reasonably be so made, Solid Waste Agency of North
ern Cook Cty. v. Army Corps of Engineers, 531 U. S. 159, 167, 172
(SWANCC), but did not consider all the factors necessary to determine
that the lands in question had, or did not have, the requisite nexus.
United States v. Riverside Bayview Homes, Inc., 474 U. S. 121, and
SWANCC establish the framework for the inquiry here. The nexus
required must be assessed in terms of the Act’s goals and purposes.
Congress enacted the law to “restore and maintain the chemical, physi
cal, 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 “wa
ters of the United States,” §§ 1311(a), 1362(12). The rationale for the
Act’s wetlands regulation, as the Corps has recognized, is that wetlands
can perform critical functions related to the integrity of other waters—
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 wet
lands, alone or in combination with similarly situated lands in the re
gion, significantly affect the chemical, physical, and biological integrity
of other covered waters understood as navigable in the traditional sense.
When, in contrast, their effects on water quality are speculative or in
substantial, they fall outside the zone fairly encompassed by the term

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“navigable waters.” Because the Corps’ theory of jurisdiction in these
cases—adjacency to tributaries, however remote and insubstantial—
goes beyond the Riverside Bayview holding, its assertion of jurisdiction
cannot rest on that case. The breadth of the Corps’ existing standard
for tributaries—which seems to leave room for regulating drains,
ditches, and streams remote from any navigable-in-fact water and carry
ing only minor water-volumes toward it—precludes that standard’s
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. Absent more
specific regulations, the Corps must establish a significant nexus on a
case-by-case basis when seeking to regulate wetlands based on adja
cency to nonnavigable tributaries, in order to avoid unreasonable appli
cations of the Act. In the instant cases the record contains evidence
pointing to a possible significant nexus, but neither the agency nor the
reviewing courts considered the issue in these terms. Thus, the cases
should be remanded for further proceedings. Pp. 759–787.
Scalia, J., announced the judgment of the Court and delivered an opin
ion, in which Roberts, C. J., and Thomas and Alito, JJ., joined. Rob
erts, C. J., filed a concurring opinion, post, p. 757. Kennedy, J., filed
an opinion concurring in the judgment, post, p. 759. Stevens, J., filed a
dissenting opinion, in which Souter, Ginsburg, and Breyer, JJ., joined,
post, p. 787. Breyer, J., filed a dissenting opinion, post, p. 811.
M. Reed Hopper argued the cause for petitioners in
No. 04–1034. With him on the briefs was Robin L. Rivett.
Timothy A. Stoepker argued the cause for petitioners in
No. 04–1384. With him on the briefs were Dennis W. Ar
cher and Paul R. Bernard.
Solicitor General Clement argued the cause for respond
ents in both cases. With him on the briefs were Assistant
Attorney General Wooldridge, Deputy Solicitor General
Hungar, Malcolm L. Stewart, Greer S. Goldman, Ellen J.
Durkee, Todd S. Kim, and Katherine W. Hazard.†
†Briefs of amici curiae urging reversal in both cases were filed for the
State of Alaska et al. by David W. Ma´ rquez, Attorney General of Alaska,
and Ruth Hamilton Heese and John T. Baker, Assistant Attorneys Gen
eral, Roderick E. Walston, Mark Shurtleff, Attorney General of Utah,
Guy R. Martin, Jeffrey Kightlinger, Thomas W. Birmingham, and Daniel

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Opinion of Scalia, J.
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 wet
lands on a parcel of land in Michigan that he owned and
S. Hentschke; for the American Farm Bureau Federation by Timothy S.
Bishop; for the American Petroleum Institute by Thomas Sayre Llewel
lyn, Harry M. Ng, and Ralph J. Colleli, Jr.; for the Attainable Housing
Alliance by Sebastian Rucci; for the Cato Institute by Timothy Lynch;
for the Claremont Institute Center for Constitutional Jurisprudence by
John C. Eastman and Edwin Meese III; for CropLife America et al. by
Richard E. Schwartz; for the Foundation for Environmental and Economic
Progress et al. by Virginia S. Albrecht, Deidre G. Duncan, David J. De-
Pippo, Ralph W. Holmen, Robin S. Conrad, and Amar D. Sarwal; for the
Home Builders Association of Central Arizona by Michael J. Pearce; for
the International Council of Shopping Centers et al. by Gus Bauman; for
the Mountain States Legal Foundation by William Perry Pendley; for the
National Association of Home Builders by Duane J. Desiderio and Thomas
J. Ward; for the National Stone, Sand and Gravel Association et al. by
Lawrence R. Liebesman; for Pulte Homes, Inc., et al. by Carter G. Phillips
and Stephen B. Kinnaird; for the Western Coalition of Arid States by
Lawrence S. Bazel and John Briscoe; for John J. Duncan, Jr., by Thomas
C. Jackson; and for Charles R. Johnson et al. by Michael E. Malamut,
Andrew R. Grainger, Martin J. Newhouse, and Martin S. Kaufman.
Briefs of amici curiae urging affirmance in both cases were filed for the
State of New York et al. by Eliot Spitzer, Attorney General of New York,
Caitlin J. Halligan, Solicitor General, Peter H. Lehner, Daniel Smirlock,
Deputy Solicitor General, Benjamin N. Gutman, Assistant Solicitor Gen
eral, and Lemuel M. Srolovic, Assistant Attorney General, Michael A.
Cox, Attorney General of Michigan, Thomas L. Casey, Solicitor Gen
eral, Susan Shinkman, and Margaret O. Murphy, and by the Attorneys
General for their respective jurisdictions as follows: Terry Goddard of
Arizona, Mike Beebe of Arkansas, Bill Lockyer of California, Richard
Blumenthal of Connecticut, Carl C. Danberg of Delaware, Robert J.
Spagnoletti of the District of Columbia, Charles J. Crist, Jr., of Florida,
Mark J. Bennett of Hawaii, Lisa Madigan of Illinois, Thomas J. Miller of
Iowa, Gregory D. Stumbo of Kentucky, Charles C. Foti, Jr., of Louisiana,
G. Steven Rowe of Maine, J. Joseph Curran, Jr., of Maryland, Thomas F.
Reilly of Massachusetts, Mike Hatch of Minnesota, Jim Hood of Missis
sippi, Jeremiah W. (Jay) Nixon of Missouri, Mike McGrath of Montana,
Kelly A. Ayotte of New Hampshire, Peter C. Harvey of New Jersey, Patri

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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
cia A. Madrid of New Mexico, Roy Cooper of North Carolina, Jim Petro
of Ohio, W. A. Drew Edmondson of Oklahoma, Hardy Myers of Oregon,
Patrick Lynch of Rhode Island, Henry McMaster of South Carolina, Paul
G. Summers of Tennessee, William H. Sorrell of Vermont, Rob McKenna
of Washington, and Peggy A. Lautenschlager of Wisconsin; for the City of
New York by Michael A. Cardozo, Leonard J. Koerner, and Hilary Melt
zer; for American Rivers et al. by Howard I. Fox; for the Association of
State and Interstate Water Pollution Control Administrators by Timothy
J. Dowling; for the Association of State Wetland Managers et al. by Pat
rick Parenteau; for the Chesapeake Bay Foundation by Jan Goldman-
Carter; for Ducks Unlimited, Inc., et al. by James Murphy, Thomas M.
France, and Neil S. Kagan; for the Environmental Law Institute by Seth
P. Waxman, Louis R. Cohen, and Leslie Carothers; for the National Miti
gation Banking Association by Margaret N. Strand, John F. Cooney, and
Royal C. Gardner; for the Western Organization of Resource Councils
et al. by Charles M. Tebbutt; for Carol M. Browner et al. by Deborah A.
Sivas, Lawrence C. Marshall, and Holly D. Gordon; for Jared M. Diamond
et al. by Jason C. Rylander; for Rep. John D. Dingell et al. by Robert
W. Adler and Amy J. Wildermuth; and for Calvin H. Johnson by
Mr. Johnson, pro se.
Briefs of amici curiae were filed in both cases for the American Plan
ning Association by Nancy Stroud; for the Mackinac Center for Public
Policy by Patrick J. Wright; for the National Association of Waterfront
Employers by Francis Edwin Froelich and Charles T. Carroll, Jr.; and
for the National Federation of Independent Business Legal Foundation by
Robert R. Gasaway and Ashley C. Parrish.
Mark A. Perry, Daniel J. Popeo, and Paul D. Kamenar filed a brief for
the Washington Legal Foundation et al. as amici curiae urging reversal
in No. 04–1034.
James Blanding Holman IV and Derb S. Carter, Jr., filed a brief for the
Ecological Society of America et al. as amici curiae urging affirmance
in No. 04–1384.
Briefs of amici curiae were filed in No. 04–1384 for Donald L. Harkins
by William J. Reisdorf; and for Macomb County, Michigan, by Mark A.
Richardson.

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without a permit. Twelve years of criminal and civil litiga
tion ensued.
The burden of federal regulation on those who would de
posit 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).1 The average applicant for an individual
permit spends 788 days and $271,596 in completing the proc
ess, and the average applicant for a nationwide permit
spends 313 days and $28,915—not counting costs of mitiga
tion or design changes. Sunding & Zilberman, The Econom
ics of Environmental Regulation by Licensing: An Assess
ment of Recent Changes to the Wetland Permitting Process,
42 Natural Resources J. 59, 74–76 (2002). “[O]ver $1.7 bil
lion is spent each year by the private and public sectors ob
taining 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., dis
senting from denial of certiorari). In this litigation, for ex
ample, 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).
1 In issuing permits, the Corps directs that “[a]ll factors which may be
relevant to the proposal must be considered including the cumulative ef
fects 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, considera
tions of property ownership and, in general, the needs and welfare of the
people.” § 320.4(a).

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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—with
out 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 juris
diction 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 drain
age 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 cov
ered by floodwaters once every 100 years. Because they in
clude 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 sur
face, 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 Na
tion’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

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the development and use (including restoration, preserva
tion, and enhancement) of land and water resources, and to
consult with the Administrator in the exercise of his author
ity 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 pol
lutant” is defined broadly to include “any addition of any pol
lutant to navigable waters from any point source,” § 1362(12),
and “pollutant” is defined broadly to include not only tradi
tional 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 con
sider 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

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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 inter
state navigable waters, 33 CFR § 328.3(a)(1) (2004), “[a]ll in
terstate waters including interstate wetlands,” § 328.3(a)(2);
“[a]ll other waters such as intrastate lakes, rivers, streams
(including intermittent streams), mudflats, sandflats, wet
lands, 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 “border
ing, 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 adja
cent to a body of navigable water,” because “the area charac
terized 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). Noting that “the transition from water to solid

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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” tra
ditional navigable waters. Id., at 135.
Following our decision in Riverside Bayview, the Corps
adopted increasingly broad interpretations of its own regula
tions 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 juris
diction 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 Govern
ment Reform, House of Representatives, Waters and Wet
lands: Corps of Engineers Needs to Evaluate Its District
Office Practices in Determining Jurisdiction, 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

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F. 3d 1336, 1340–1342 (CA11 1997), and dry arroyos con
nected 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 jurisdic
tion 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 wa
ters,” id., at 171—which, unlike the wetlands at issue in Riv
erside Bayview, did not “actually abu[t] on a navigable wa
terway,” 531 U. S., at 167—were not included as “waters of
the United States.”
Following our decision in SWANCC, the Corps did not sig
nificantly revise its theory of federal jurisdiction under
§ 1344(a). The Corps provided notice of a proposed rule
making in light of SWANCC, 68 Fed. Reg. 1991 (2003), but
ultimately did not amend its published regulations. Be
cause 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 adja
cent 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) (2002)).
Even after SWANCC, the lower courts have continued to
uphold the Corps’ sweeping assertions of jurisdiction over
ephemeral channels and drains as “tributaries.” For exam
ple, courts have held that jurisdictional “tributaries” include

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the “intermittent flow of surface water through approxi
mately 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 Restora
tion 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 Sono
ran, Inc. v. Flowers, 408 F. 3d 1113, 1118 (CA9 2005).2
These judicial constructions of “tributaries” are not outli
ers. Rather, they reflect the breadth of the Corps’ determi
nations 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 dis
trict 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 man-made, intermit
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.

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tently 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 “adja
cent” and jurisdictional. Id., at 19. And the Corps has suc
cessfully defended such theories of “adjacency” in the courts,
even after SWANCC’s excision of “isolated” waters and wet
lands from the Act’s coverage. One court has held since
SWANCC that wetlands separated from flood control chan
nels 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 navi
gable waters is required, there is no ‘direct abutment’ re
quirement” under SWANCC for “ ‘adjacency.’ ” 376 F. 3d
629, 639 (2004) (Rapanos II). And even the most insubstan
tial hydrologic connection may be held to constitute a “sig
nificant 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 inev
itably flow towards and mix with water from connecting bod

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ies,” 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 Ra
panos 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 Tittaba
wassee 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 occa
sional 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 juris
diction” 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 af
firmed, holding that there was federal jurisdiction over the

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wetlands at all three sites because “there were hydrological
connections between all three sites and corresponding adja
cent 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 trian
gular 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.
932 (2005), to decide whether these wetlands constitute “wa
ters of the United States” under the Act, and if so, whether
the Act is constitutional.
III
The Rapanos petitioners contend that the terms “naviga
ble 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

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States.” 33 U. S. C. § 1362(7). Moreover, the Act provides,
in certain circumstances, for the substitution of state for fed
eral 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 . . . in
cluding wetlands adjacent thereto.” § 1344(g)(1) (emphasis
added). This provision shows that the Act’s term “naviga
ble waters” includes something more than traditional naviga
ble waters. We have twice stated that the meaning of “nav
igable waters” in the Act is broader than the traditional
understanding of that term, SWANCC, 531 U. S., at 167; Riv
erside Bayview, 474 U. S., at 133.3 We have also empha
sized, however, that the qualifier “navigable” is not devoid of
significance, SWANCC, supra, at 172.
We need not decide the precise extent to which the quali
fiers “navigable” and “of the United States” restrict the cov
erage 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 wa
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 tradi
tional navigable waters, both interstate and intrastate. This would pre
serve 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 under
stood, 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 defini
tion retains some of its traditional meaning.

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ters of the United States” in § 1362(7) cannot bear the expan
sive meaning that the Corps would give it.
The Corps’ expansive approach might be arguable if the
CWA defined “navigable waters” as “water of the United
States.” But “the waters of the United States” is some
thing else. The use of the definite article (“the”) and the
plural number (“waters”) shows 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).4 On this definition, “the waters of the
United States” include only relatively permanent, standing
or flowing bodies of water.5 The definition refers to water
4 Justice Kennedy observes, post, at 770 (opinion concurring in judg
ment), 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 defini
tion section of an otherwise prosaic, indeed downright tedious, statute.
The duller and more commonplace meaning is obviously intended.
5 By describing “waters” as “relatively permanent,” we do not necessar
ily exclude streams, rivers, or lakes that might dry up in extraordinary
circumstances, such as drought. We also do not necessarily exclude sea
sonal 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 800. Common sense and common usage distinguish be
tween a wash and seasonal river.
Though scientifically precise distinctions between “perennial” and “in
termittent” flows are no doubt available, see, e. g., Dept. of Interior, U. S.
Geological Survey, E. Hedman & W. Osterkamp, Streamflow Characteris
tics 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 streambed is continuous and
frequent enough to disqualify the channel as a “wate[r] of the United

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as found in “streams,” “oceans,” “rivers,” “lakes,” and “bod
ies” 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,” con
notes a continuous flow of water in a permanent channel—
especially when used in company with other terms such as
“rivers,” “lakes,” and “oceans.” 6 None of these terms en
compasses transitory puddles or ephemeral flows of water.
The restriction of “the waters of the United States” to
exclude channels containing merely intermittent or ephem-
States.” It suffices for present purposes that channels containing perma
nent flow are plainly within the definition, and that the dissent’s “intermit
tent” and “ephemeral” streams, post, at 801—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.
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. (emphasis added). The definition of the verb form of “stream” con
tains 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
801, n. 11 (opinion of Stevens, J.)—useful oxymora. Properly speaking,
such entities constitute extant “streams” only while they are “continu
ous[ly] flow[ing]”; and the usually dry channels that contain them are
never “streams.” Justice Kennedy apparently concedes that “an inter
mittent flow can constitute a stream” only “while it is flowing,” post, at
770 (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 evapo
rates along with the water in such regularly dry channels.

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eral flow also accords with the commonsense understanding
of the term. In applying the definition to “ephemeral
streams,” “wet meadows,” storm sewers and culverts, “di
rectional 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 “naviga
ble waters” (the defined term) further confirms that it con
fers jurisdiction only over relatively permanent bodies of
water. The Act adopted that traditional term from its pred
ecessor statutes. See SWANCC, 531 U. S., at 180 (Stevens,
J., dissenting). On the traditional understanding, “navigable
waters” included only discrete bodies of water. For exam
ple, in The Daniel Ball, we used the terms “waters” and
“rivers” interchangeably. 10 Wall., at 563. And in Appala
chian Electric, we consistently referred to the “navigable
waters” as “waterways.” 311 U. S., at 407–409. Plainly, be
cause 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 “navi
gable 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 limi
tation 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 iden
tifiable as ‘waters’ ” than the wetlands adjacent to such fea

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tures. 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 wet
lands 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,’ ” id., at 131. Likewise, in both Riverside
Bayview and SWANCC, we repeatedly described the “navi
gable 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 in
terpretation are typically dry channels described as “open
waters.”
Most significant of all, the CWA itself categorizes the chan
nels 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 convey
ance, 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 dis
charged. ” 33 U. S. C. § 1362(14). It also defines “ ‘dis
charge of a pollutant’ ” as “any addition of any pollutant to
navigable waters from any point source.” § 1362(12)(A)
(emphasis added). The definitions thus conceive of “point
sources” and “navigable waters” as separate and distinct cat
egories. The definition of “discharge” would make little
sense if the two categories were significantly overlapping.
The separate classification of “ditch[es], channel[s], and con

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duit[s]”—which are terms ordinarily used to describe the wa
tercourses through which intermittent waters typically
flow—shows that these are, by and large, not “waters of the
United States.” 7
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 perma
nently as well as intermittently,” post, at 802 (opinion of Stevens, J.); see
also post, at 771–772 (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 perma
nently flows is ordinarily described as a “stream,” not as a “channel,” be
cause 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 streambeds. 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 802, n. 12 (opinion of Stevens, J.). On its only natural read
ing, such a statute that treats “waters” separately from “ditch[es], chan
nel[s], tunnel[s], and conduit[s],” thereby distinguishes between continu
ously 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 772 (opinion of Ken
nedy, J.), and the “mains, pipes, hydrants, machinery, buildings, and other
appurtenances and incidents” of the city of Knoxville’s “system of water
works,” Knoxville Water Co. v. Knoxville, 200 U. S. 22, 27 (1906), cited
post, at 802, 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 772 (opinion of Kennedy, J.); post, at 802,
n. 12 (opinion of Stevens, J.). But this does not contradict our interpre
tation, which asserts that relatively continuous flow is a necessary condi
tion for qualification as a “water,” not an adequate condition. Just as
ordinary usage does not treat typically dry beds as “waters,” so also it

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Moreover, only the foregoing definition of “waters” is con
sistent with the CWA’s stated “policy of Congress to recog
nize, preserve, and protect the primary responsibilities and
rights of the States to prevent, reduce, and eliminate pollu
tion, [and] to plan the development and use (including resto
ration, 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 pro
gram in the 1977 amendments, see 91 Stat. 1601. Thus the
policy plainly referred to something beyond the subse
quently 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 re
sponsibilities 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 there
fore an unlikely reading of the phrase “the waters of the
United States.” 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’ interpre
tation of the statute is impermissible. As we noted in
does not treat such elaborate, man-made, enclosed systems as “waters” on
a par with “streams,” “rivers,” and “oceans.”
8 Justice Kennedy contends that the Corps’ preservation of the “re
sponsibilities and rights” of the States is adequately demonstrated by the
fact that “33 States plus the District of Columbia have filed an amici brief
in this litigation” in favor of the Corps’ interpretation, post, at 777. But
it makes no difference to the statute’s stated purpose of preserving States’
“responsibilities and rights,” § 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 attrac
tive to shift to another entity controversial decisions disputed between
politically powerful, rival interests. That, however, is not what the stat
ute provides.

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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, 767–768, n. 30 (1982); Hess v.
Port Authority Trans-Hudson Corporation, 513 U. S. 30, 44
(1994). The extensive federal jurisdiction urged by the Gov
ernment would authorize the Corps to function as a de facto
regulator of immense stretches of intrastate land—an au
thority 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’ inter
pretation 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 wa
ters 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).9
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 776—that is,

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In sum, on its only plausible interpretation, the phrase
“the waters of the United States” includes only those rela
tively 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 drain
age 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). See 391 F. 3d, at 708–
709. Likewise in Rapanos II, the Sixth Circuit held that
the nearby ditches were “tributaries” under § 328.3(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 wet
lands 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
because our resolution both eliminates some jurisdiction that is clearly
constitutional and traditionally federal, and retains some that is question
ably 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 782, 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, 546 U. S. 243, 286 (2006) (Scalia, J., dissenting)—and it aligns
even worse with the preservation of traditional state land-use regulation.

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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 there
fore address in this Part whether a wetland may be con
sidered “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 am
biguity in drawing the boundaries of any “waters”:
“[T]he Corps must necessarily choose some point at
which water ends and land begins. Our common expe
rience tells us that this is often no easy task: the transi
tion 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]” tradi
tional navigable waters: “Faced with such a problem of de
fining the bounds of its regulatory authority,” we held, the
agency could reasonably conclude that a wetland that “ad
join[ed]” waters of the United States is itself a part of those
waters. Id., at 132, 135, and n. 9. The difficulty of delineat
ing the boundary between water and land was central to our
reasoning in the case: “In view of the breadth of federal reg
ulatory authority contemplated by the Act itself and the in
herent difficulties of defining precise bounds to regulable
waters, the Corps’ ecological judgment about the relation
ship between waters and their adjacent wetlands provides

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an adequate basis for a legal judgment that adjacent wet
lands may be defined as waters under the Act.” Id., at 134
(emphasis added).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 ‘naviga
ble waters’ that informed our reading of the CWA in River
side Bayview Homes.” 531 U. S., at 167 (emphasis added).
In particular, SWANCC rejected the notion that the ecologi
cal considerations upon which the Corps relied in Riverside
Bayview—and upon which the dissent repeatedly relies
today, see post, at 796, 797–798, 798–799, 800, 803, 806, 807,
809–810—provided an independent basis for including enti
ties like “wetlands” (or “ephemeral streams”) within the
phrase “the waters of the United States.” SWANCC found
such ecological considerations irrelevant to the question
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. Obi
ter approval of that proposition might be inferred, however, from the opin
ion’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 re
garded 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 wet
lands’ 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).

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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 re
solve that ambiguity in favor of treating all abutting wet
lands 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 be
tween “waters” and wetlands, are “adjacent to” such waters
and covered by the Act. Wetlands with only an intermit
tent, 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 “sig
nificant nexus” in SWANCC. 531 U. S., at 167. Thus, es
tablishing 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 enforce
ment 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 re

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quirement 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 signifi
cantly 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 enact
ment, lower courts have held that the discharge into inter
mittent 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 sepa
rated 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, in
termittently flowing channels themselves constitute “point
sources” under the Act. The definition of “point source” in
cludes “any pipe, ditch, channel, tunnel, conduit, well, dis
crete 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 chan
nel to be a point source include United States v. Ortiz, 427
F. 3d 1278, 1281 (CA10 2005) (a storm drain that carried

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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 Envi
ronment 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 per
mitting requirement of § 1342(a), “dredged or fill material,”
which is typically deposited for the sole purpose of staying
put, does not normally wash downstream,11 and thus does
not normally constitute an “addition . . . to navigable waters”
when deposited in upstream isolated wetlands. §§ 1344(a),
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 mate
rial] makes its way downstream,” post, at 807 (citation omitted). See also
post, at 774–775 (opinion of Kennedy, J.). By contrast, amici cite multi
ple 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 appre
ciable distance from them lacks credibility.” R. Pierce, Technical Princi
ples Related to Establishing the Limits of Jurisdiction for Section 404 of
the Clean Water Act 34–40 (Apr. 2003), available at http://www.wetland
training.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, how
ever, to reach the unremarkable conclusion that the deposit of mobile pol
lutants 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.

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1362(12). The Act recognizes this distinction by provid
ing a separate permitting program for such discharges in
§ 1344(a). It does not appear, therefore, that the inter
pretation we adopt today significantly reduces the scope of
§ 1342.
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 re
quiring 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 re
quired under § 1342 appears substantially similar, if not iden
tical, 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 ob
servation 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 nar
rowing the definition of “the waters of the United States”
will hamper federal efforts to preserve the Nation’s wet
lands. 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 preserva
tion. In any event, a Comprehensive National Wetlands
Protection Act is not before us, and the “wis[dom]” of such a
statute, post, at 805 (opinion of Stevens, J.), is beyond our

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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 struc
ture, 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 ex
clusively on two sources: “[o]ur unanimous opinion in River
side Bayview,” post, at 792; and “Congress’ deliberate ac
quiescence in the Corps’ regulations in 1977,” post, at 797.
Each of these is demonstrably inadequate to support the ap
parently 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 792, is wholly implausible.
First, Riverside Bayview could not possibly support the dis
sent’s acceptance of the Corps’ inclusion of dry beds as “trib
utaries,” post, at 804, 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 nonnavigable
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 be
yond reason to include, inter alia, the 100-year floodplain of
covered waters. See supra, at 728. The dissent notes that
Riverside Bayview quoted without comment the Corps’ de
scription of “adjacent” wetlands as those “ ‘that form the bor
der of or are in reasonable proximity to other waters’ . . . of

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the United States.” Post, at 793 (citing 474 U. S., at 134
(quoting 42 Fed. Reg. 37128)). As we have already dis
cussed, this quotation provides no support for the inclusion
of physically unconnected wetlands as covered “waters.”
See supra, at 741, 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’ ” wet
lands are nevertheless covered by the Act, post, at 793 (quot
ing 474 U. S., at 135, n. 9). Of course, this footnote says
nothing to support the dissent’s broad definition of “adja
cent”—quite the contrary, the quoted sentence uses “adja
cent” 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 as
sertion 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 wet
lands,” and (2) we must defer to the Corps’ interpretation
of the ambiguous word “adjacent.” Post, at 805–806. But
this is mere legerdemain. The phrase “adjacent wetlands”
is not part of the statutory definition that the Corps is au
thorized to interpret, which refers only to “the waters of the
United States,” 33 U. S. C. § 1362(7).12 In expounding the
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 805, that reference merely confirms that the statutory
definition can be read to include some wetlands—namely, those that di
rectly “abut” covered waters. Riverside Bayview explicitly acknowl
edged that § 1344(g)(1) “does not conclusively determine the construction

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term “adjacent” as used in Riverside Bayview, we are ex
plaining our own prior use of that word to interpret the
definitional phrase “the waters of the United States.” How
ever 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 740–742.
The dissent would distinguish SWANCC on the ground
that it “had nothing to say about wetlands,” post, at 794—
i. e., it concerned “isolated ponds” rather than isolated wet
lands. 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 con
stitute “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 to
day’s dissent has written, “[i]f, as I believe, actually naviga
ble 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 ‘wa
ters of the United States’ potentially covered by the stat
ute.” 531 U. S., at 187, n. 13 (Stevens, J., dissenting).
The only other ground that the dissent offers to distin
guish 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 dif
ference—without actual abutment, it raises no boundary
to be placed on the use of the term ‘waters’ elsewhere in the Act (particu
larly 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 (emphasis added).

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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 tribu
taries, its reasons for including those wetlands are strictly
ecological—such wetlands would be included because they
“serve . . . important water quality roles,” post, at 796, and
“play important roles in the watershed,” post, at 803. 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, rear
ing and resting sites for aquatic or land species,’ ” and
“ ‘serve as valuable storage areas for storm and flood wa
ters,’ ” post, at 796. The dissent’s exclusive focus on ecologi
cal 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’ deliber
ate acquiescence in the Corps’ regulations in 1977,” post,
at 797—noting that “[w]e found [this acquiescence] signifi
cant in Riverside Bayview,” and even “acknowledged in
SWANCC” that we had done so, ibid. SWANCC “acknowl
edged” that Riverside Bayview had relied on congressional
acquiescence only to criticize that reliance. It reasserted in
no uncertain terms our oft-expressed skepticism toward
reading the tea leaves of congressional inaction:
“Although we have recognized congressional acquies
cence 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 at

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tenuated. Because subsequent history is less illuminat
ing than the contemporaneous evidence, respondents
face a difficult task in overcoming the plain text and im
port of [§ 1344(a)].” 531 U. S., at 169–170 (brackets, ci
tations, internal quotation marks, and footnote omitted).
Congress takes no governmental action except by legisla
tion. What the dissent refers to as “Congress’ deliberate
acquiescence” should more appropriately be called Con
gress’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 understand
ing of a statute with an amended agency interpretation.”
SWANCC, supra, at 169–170, n. 5 (emphasis added).
The dissent falls far short of producing “overwhelming evi
dence” that Congress considered and failed to act upon the
“precise issue” before the Court today—namely, what consti
tutes an “adjacent” wetland covered by the Act. Citing Riv
erside Bayview’s account of the 1977 debates, the dissent
claims nothing more than that Congress “conducted exten
sive debates about the Corps’ regulatory jurisdiction over
wetlands [and] rejected efforts to limit that jurisdiction . . . .”
Post, at 797. 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 wet
lands (defined as wetlands periodically inundated by contigu
ous navigable waters),” 474 U. S., at 136. In rejecting this

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proposal, Congress merely failed to enact a limitation of “wa
ters” to include only navigable-in-fact waters—an interpre
tation we affirmatively reject today, see supra, at 731—and a
definition of wetlands based on “periodi[c] inundat[ion]” that
appears almost nowhere in the briefs or opinions of these
cases.13 No plausible interpretation of this legislative inac
tion 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
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 oppo
site. 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 773. Of course Justice Kennedy himself fails to ob
serve this supposed presumption, since his “significant nexus” test makes
no exception for wetlands created by inundation. In any event, the lan
guage 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” wet
lands 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 con
tinuous physical connection that the rest of the Riverside Bayview opinion
required, see supra, at 740–742. Thus, it is evident that the quoted lan
guage 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 474 U. S., at 125) that the only covered
wetlands are those created by inundation. As long as the wetland is “ad
jacent” to covered waters, said Riverside Bayview, its creation vel non by
inundation is irrelevant.

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restricted the reach of the Corps’ jurisdiction” would not
have excised adjacent wetlands, ibid. Both of these conclu
sions 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 799; see also post, at 787–788, 807.
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 inter
preting it broadly to cover such ditches and streams ad
vances the purpose of the Act, the Corps’ approach should
command our deference.” Post, at 804. 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 authoriza
tions. 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 state
ment, post, at 799, that “[w]hether the benefits of particular

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conservation measures outweigh their costs is a classic ques
tion of public policy that should not be answered by ap
pointed judges.” Neither, however, should it be answered
by appointed officers of the Corps of Engineers in contradic
tion of congressional direction. It is the dissent’s opinion,
and not ours, which appeals not to a reasonable interpreta
tion 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 pur
pose.” Post, at 776. 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 re
quire 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 782, 780. 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, hold
ing instead that all physically connected wetlands are cov
ered. 474 U. S., at 135, n. 9. It is true enough that one

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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 argu
ment that physically unconnected ponds could be included
based on their ecological connection to covered waters. In
fact, Justice Kennedy acknowledges that neither River
side Bayview nor SWANCC required, for wetlands abutting
navigable-in-fact waters, the case-by-case ecological deter
mination that he proposes for wetlands that neighbor non
navigable tributaries. See post, at 780. Thus, Justice
Kennedy misreads SWANCC’s “significant nexus” state
ment as mischaracterizing Riverside Bayview to adopt a
case-by-case test of ecological significance; and then trans
fers that standard to a context that Riverside Bayview ex
pressly 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 Bay
view did address (wetlands abutting navigable waterways).
Truly, this is “turtles all the way down.” 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
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 Inter
pretive Theory of Culture, in The Interpretation of Cultures 28–29 (1973).
In our favored version, an Eastern guru affirms that the earth is sup
ported 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 ele
phant 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.”

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reading Justice Kennedy’s exegesis, that the crucial provi
sion of the text of the CWA was a jurisdictional requirement
of “significant nexus” between wetlands and navigable wa
ters. 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 com
patible with what the Act does establish as the jurisdictional
criterion: “waters of the United States.” Wetlands are “wa
ters of the United States” if they bear the “significant nexus”
of physical connection, which makes them as a practical mat
ter indistinguishable from waters of the United States.
What other nexus could conceivably cause them to be “wa
ters 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 780 (emphasis added).
But what possible linguistic usage would accept that what
ever (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 prop
erly 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 apply
ing, he purports to do so by reference to what he calls the
“purpose” of the statute. Its purpose is to clean up the wa
ters of the United States, and therefore anything that might
“significantly affect” the purity of those waters bears a “sig
nificant 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 pur
pose 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

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only purpose of the statute. So is the preservation of pri
mary state responsibility for ordinary land-use decisions.
33 U. S. C. § 1251(b). Justice Kennedy’s test takes no ac
count 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 in
stead 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’.15 In
another respect, however, it is more extreme. At least Jus
tice Stevens can blame his implausible reading of the stat
ute upon the Corps. His error consists of giving that
agency more deference than reason permits. Justice Ken
nedy, 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
15 It is unclear how much more moderate the flouting is, since Justice
Kennedy’s “significant nexus” standard is perfectly opaque. When, ex
actly, does a wetland “significantly affect” covered waters, and when are
its effects “in contrast . . . speculative or insubstantial”? Post, at 780.
Justice Kennedy does not tell us clearly—except to suggest, post, at
782, that “ ‘ “isolated” is generally a matter of degree’ ” (quoting Leibo
witz & Nadeau, Isolated Wetlands: State-of-the-Science and Future Direc
tions, 23 Wetlands 663, 669 (2003)). As the dissent hopefully observes,
post, at 808, such an unverifiable standard is not likely to constrain an
agency whose disregard for the statutory language has been so long mani
fested. 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
783, Justice Kennedy tips a wink at the agency, inviting it to try its
same expansive reading again.

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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 wet
lands in question are “adjacent” to these “waters” in the
sense of possessing a continuous surface connection that cre
ates the boundary-drawing problem we addressed in River
side Bayview.
* * *
We vacate the judgments of the Sixth Circuit in both
No. 04–1034 and No. 04–1384, and remand both cases for fur
ther proceedings.
It is so ordered.
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 rule
making to consider “issues associated with the scope of wa
ters that are subject to the Clean Water Act (CWA), in light
of the U. S. Supreme Court decision in [SWANCC].” 68

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Fed. Reg. 1991 (2003). The “goal of the agencies” was “to
develop proposed regulations that will further the public in
terest by clarifying what waters are subject to CWA juris
diction and affording full protection to these waters through
an appropriate focus of Federal and State resources consist
ent 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 Re
sources 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 re
fining 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 es
sentially boundless view of the scope of its power. The up
shot 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 un
usual 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 795–796, 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

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Kennedy, J., concurring in judgment
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 circum
stances presented there, that to constitute “ ‘navigable wa
ters’ ” under the Act, a water or wetland must possess a “sig
nificant 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 requi
site 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 back
ground 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 (or Act) is “to re
store and maintain the chemical, physical, and biological in
tegrity of the Nation’s waters.” 33 U. S. C. § 1251(a). To
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” (emphasis added)). The agen
cies can decide for themselves whether, as the SWANCC dissenter sug
gests, it was wise for them to take no action in response to SWANCC.

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that end, the statute, among other things, prohibits “the dis
charge of any pollutant by any person” except as provided
in the Act. § 1311(a). As relevant here, the term “dis
charge 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, muni
tions, chemical wastes, biological materials, radioactive ma
terials, 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) (categor
ically 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 cer
tain 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’) per
mitting decisions. See §§ 1311(a), 1342(a), 1344(c). Dis
charge of pollutants without an appropriate permit may re
sult 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 out
come turns on whether that phrase reasonably describes cer
tain 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.

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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, natu
ral line impressed on the bank, shelving, changes in the char
acter of soil, destruction of terrestrial vegetation, the pres
ence 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 722, 734,
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 suffi
cient 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 spe
cies typically adapted to saturated soil conditions, deter
mined in accordance with the United States Fish and Wild
life 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 sea
son 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.

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army.mil/permit/documents/87manual.pdf (all Internet mate
rials 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 ac
tion initiated by the United States in the United States Dis
trict 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’ defini
tion 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 sur
face 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 naviga
ble. A state official testified that he observed carp spawn
ing 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 wet

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lands and that a surface-water connection linked the wet
lands 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 delin
eated (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 in
cluded between 48 and 58 acres of wetlands, Rapanos al
legedly 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 con
ducted 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

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three parcels. On the merits the court ruled in the Govern
ment’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. 932 (2005).
The second consolidated case, Carabell, No. 04–1384, in
volves 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 lo
cated roughly one mile from Lake St. Clair, a 430-square
mile lake located between Michigan and Canada that is popu
lar for boating and fishing and produces some 48 percent of
the sport fish caught in the Great Lakes, see Brief for Ma
comb 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 landown
ers 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 consult
ant 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.

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In 1993 petitioners Keith and June Carabell sought a per
mit 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 de
stroyed, could result in an increased risk of erosion and deg
radation of water quality in the Sutherland-Oemig Drain,
Auvase Creek, and Lake St. Clair.” Id., at 127a. The dis
trict office denied the permit, and the Corps upheld the de
nial in an administrative appeal. The Carabells, challenging
both the Corps’ jurisdiction and the merits of the permit de
nial, 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 (2003),
and the United States Court of Appeals for the Sixth Circuit
affirmed, 391 F. 3d 704 (2004). This Court granted certio
rari to consider the jurisdictional question. 546 U. S. 932
(2005).
II
Twice before the Court has construed the term “navigable
waters” in the Clean Water Act. In United States v. River
side 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

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Lake St. Clair, see United States v. Riverside Bayview
Homes, Inc., 729 F. 2d 391, 392 (CA6 1984) (decision on re
view in Riverside Bayview), though in that case, unlike Car
abell, the lands at issue formed part of a wetland that di
rectly 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) (1985), slowing the flow of
runoff into lakes, rivers, and streams so as to prevent flood
ing 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 in
tent 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 De
fense Council, Inc., 467 U. S. 837, 842–845 (1984)), the Court
held that “the Corps’ ecological judgment about the relation
ship between waters and their adjacent wetlands provides
an adequate basis for a legal judgment that adjacent wet
lands 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 adja
cent 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 iso
lated in the sense of being unconnected to other waters cov
ered 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 “naviga

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ble 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 iso
lated 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 frame
work 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 rea
sonable 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 ex
emplified 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, jurisdic
tion under the Act is lacking. Because neither the plurality
nor the dissent addresses the nexus requirement, this sepa
rate 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 731; Riverside Bayview, supra, at 133; see
also SWANCC, supra, at 167. This conclusion is supported
by “the evident breadth of congressional concern for pro
tection of water quality and aquatic ecosystems.” River
side Bayview, supra, at 133; see also Milwaukee v. Illinois,
451 U. S. 304, 318 (1981) (describing the Act as “an all

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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 nonnaviga
ble 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 navi
gable waters (other than those waters which are pres
ently 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 shore
ward 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 inter
state 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

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bodies,’ ” ante, at 732 (quoting Webster’s New International
Dictionary 2882 (2d ed. 1954) (hereinafter Webster’s Sec
ond)), the plurality would conclude that the phrase “naviga
ble waters” permits Corps and EPA jurisdiction only over
“relatively permanent, standing or flowing bodies of water,”
ante, at 732—a category that in the plurality’s view includes
“seasonal” rivers, that is, rivers that carry water continu
ously except during “dry months,” but not intermittent or
ephemeral streams, ante, at 732–734, 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 742.
The plurality’s first requirement—permanent standing
water or continuous flow, at least for a period of “some
months,” ante, at 732–733, 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 ir
regular flows are too insignificant to be of concern in a stat
ute focused on “waters,” that may not always be true.
Areas in the western parts of the Nation provide some ex
amples. 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 de
structive 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 plural
ity’s test, it is illustrative of what often-dry watercourses

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can become when rain waters flow. See, e. g., County of
Los Angeles Dept. of Public Works, Water Resources Divi
sion: 2002–2003 Hydrologic Report, Runoff, Daily Dis
charge, F377–R BOUQUET CANYON CREEK at Urban
dale Avenue 11107860 Bouquet Creek Near Saugus, CA,
http://ladpw.org/wrd/report/0203/runoff/discharge.cfm (indi
cating 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 defi
nition 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 “navi
gable” indicates a focus on waterways rather than floods,
Congress’ use of “waters” instead of “water,” ante, at 732,
does not necessarily carry the connotation of “relatively per
manent, standing or flowing bodies of water,” ibid. (And
contrary to the plurality’s suggestion, ante, at 732, n. 4, there
is no indication in the dictionary that the “ ‘flood or inunda
tion’ ” 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 geo
graphical features such as oceans, rivers, [and] lakes,’ ” ante,
at 732 (quoting Webster’s Second 2882)—the dissent is cor
rect 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 733, n. 6 (quot
ing Webster’s Second 2493), while it is flowing. See post,
at 801 (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 reason
ably interpret the Act to cover the paths of such imperma
nent streams.

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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 fea
tures such as oceans, rivers, [and] lakes.’ ” Ante, at 735
(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 fea
tures” could just as well refer to intermittent streams carry
ing 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; spe
cif[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 dis
cernible, confined and discrete conveyance, including but not
limited to any pipe, ditch, channel, tunnel, conduit, well, dis
crete 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). Inter
preting the point-source definition, the plurality presumes,
first, that the point-source examples describe “watercourses
through which intermittent waters typically flow,” and sec
ond, that point sources and navigable waters are “separate
and distinct categories.” Ante, at 735–736. From this the

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plurality concludes, by a sort of negative inference, that navi
gable waters may not be intermittent. The conclusion is un
sound. 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 802.
The plurality’s second limitation—exclusion of wetlands
lacking a continuous surface connection to other jurisdic
tional waters—is also unpersuasive. To begin with, the plu
rality is wrong to suggest that wetlands are “indistinguish
able” from waters to which they bear a surface connection.
Ante, at 755. Even if the precise boundary may be impre
cise, a bog or swamp is different from a river. The question
is what circumstances permit a bog, swamp, or other nonnav
igable wetland to constitute a “navigable water” under the
Act—as § 1344(g)(1), if nothing else, indicates is sometimes
possible, see supra, at 767–768. Riverside Bayview ad
dressed 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 irrel
evant 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 wa
terways.” Id., at 135, n. 9. “If it is reasonable,” the Court
explained, “for the Corps to conclude that in the majority

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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 per
missible even when it reaches wetlands holding moisture dis
connected from adjacent water bodies, id., at 135, and n. 9,
Riverside Bayview’s observations about the difficulty of de
fining 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 water
ways. 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 751, n. 13—
would again overlook the opinion’s broader focus on wet
lands’ “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 “contin
uous surface connection,” ante, at 742. The Court in River
side 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

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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 over
ruling 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 Bay
view. 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), cov
ers 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 treat
ment 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 744. As the dissent points
out, this proposition seems questionable as an empirical mat
ter. See post, at 806–807. It seems plausible that new or
loose fill, not anchored by grass or roots from other vegeta
tion, 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

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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, Rebuilding a River
Upstate, For the Love of a Tiny Mussel, 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 nutri
ents, toxins, and pathogens that were trapped, neutralized,
and perhaps amenable to filtering or detoxification in the
wetlands. See U. S. Congress, Office of Technology Assess
ment, 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 floodwater, impurities, or
runoff that would have been stored or contained in the wet
lands will instead flow out to major waterways. With these
concerns in mind, the Corps’ definition of adjacency is a rea
sonable one, for it may be the absence of an interchange of
waters prior to the dredge and fill activity that makes pro
tection of the wetlands critical to the statutory scheme.

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In sum the plurality’s opinion is inconsistent with the Act’s
text, structure, and purpose. As a fallback the plural
ity suggests that avoidance canons would compel its read
ing even if the text were unclear. Ante, at 737–738. 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 au
thority 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 737, 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 pro
vision as evidence that a clear statement supporting juris
diction 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 inter
preting the Act to require a significant nexus with navigable
waters, the Court avoided applications—those involving wa
ters without a significant nexus—that appeared likely, as
a category, to raise constitutional difficulties and federal
ism concerns. Here, in contrast, the plurality’s interpreta
tion 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 wa
ters were traditionally subject to federal authority. On the
other hand, by saying the Act covers wetlands (however re
mote) possessing a surface-water connection with a continu
ously flowing stream (however small), the plurality’s reading
would permit applications of the statute as far from tradi
tional federal authority as are the waters it deems beyond

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the statute’s reach. Even assuming, then, that federal reg
ulation 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 782–783, 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 State of New York et al. 1–3. These
amici note, among other things, that the Act protects down
stream 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 de
struction as “backfilling . . . wet fields,” ante, at 721, 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 734, to the suggestion,
seemingly contrary to Congress’ judgment, that discharge of
fill material is inconsequential for adjacent waterways, ante,
at 744, and n. 11—seems unduly dismissive of the inter
ests asserted by the United States in these cases. Impor
tant 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 evi
dence indicates that wetlands play a critical role in control
ling 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 Re

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moval of Nitrate and Sulfate in Freshwater Wetland Sedi
ments, 34 J. Env. Quality 2062 (2005). It is true, as the plu
rality indicates, that environmental concerns provide no
reason to disregard limits in the statutory text, ante, at 745–
746, 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 plu
rality presents its interpretation of the Act as the only per
missible reading of the plain text, ante, at 739, 742, 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 oper
ate 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 758 (concurring opin
ion). 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 “navi
gable 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 suscep
tible 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 even
tually may flow into traditional navigable waters. The def

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Kennedy, J., concurring in judgment
erence 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 768. 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 up
holding 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 ex
istence of a significant nexus between the wetlands in ques
tion and navigable waters in the traditional sense. The re
quired 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 “naviga
ble 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

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Kennedy, J., concurring in judgment
CFR § 320.4(b)(2). Accordingly, wetlands possess the requi
site nexus, and thus come within the statutory phrase “navi
gable waters,” if the wetlands, either alone or in combination
with similarly situated lands in the region, significantly af
fect 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’ ecologi
cal functions vis-a` -vis other covered waters are the basis for
the Corps’ regulation of them, post, at 796, 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 796. 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 wa
ters, 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 hold
ing of Riverside Bayview. Furthermore, although the Riv
erside 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 Riv
erside Bayview’s reasoning—supporting jurisdiction without
any inquiry beyond adjacency—could apply equally to wet
lands adjacent to certain major tributaries. Through regu

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lations or adjudication, the Corps may choose to identify cat
egories 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 incor
porating navigable waters.
The Corps’ existing standard for tributaries, however, pro
vides 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] physi
cal characteristics,” § 328.3(e). See supra, at 761. This
standard presumably provides a rough measure of the vol
ume and regularity of flow. Assuming it is subject to rea
sonably consistent application, but see U. S. General Ac
counting 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 carry
ing only minor water volumes toward 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 tradi
tionally understood. Indeed, in many cases wetlands adja
cent to tributaries covered by this standard might appear

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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 estab
lish its jurisdiction. Absent more specific regulations, how
ever, 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 nec
essary to avoid unreasonable applications of the statute.
Where an adequate nexus is established for a particular wet
land, 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 out
lined here.
This interpretation of the Act does not raise federalism or
Commerce Clause concerns sufficient to support a presump
tion against its adoption. To be sure, the significant-nexus
requirement may not align perfectly with the traditional ex
tent of federal authority. Yet in most cases regulation of
wetlands that are adjacent to tributaries and possess a sig
nificant nexus with navigable waters will raise no serious
constitutional or federalism difficulty. Cf. Pierce County v.
Guillen, 537 U. S. 129, 147 (2003) (upholding federal legisla
tion “aimed at improving safety in the channels of com
merce”); Oklahoma ex rel. Phillips v. Guy F. Atkinson Co.,
313 U. S. 508, 525–526 (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

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part in flood control on its tributaries . . . . [T]he exercise
of the granted power of Congress to regulate interstate com
merce may be aided by appropriate and needful control of
activities and agencies which, though intrastate, affect that
commerce”). As explained earlier, moreover, and as exem
plified by SWANCC, the significant-nexus test itself prevents
problematic applications of the statute. See supra, at 776;
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, 17 (2005) (“[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 sig
nificant 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 jurisdic
tion 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 ex
pert 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

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sites” and thus could not assert that the wetlands were per
forming important pollutant-trapping functions, ibid., he
did observe:
“we have a situation in which the flood water attenua
tion 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 761–762, the District Court
made extensive findings regarding water tables and drain
age on the parcels at issue. In applying the Corps’ jurisdic
tional 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, particu
larly if supplemented by further evidence about the signifi
cance 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 down
stream water quality, this standard was too uncertain.
Under the analysis described earlier, supra, at 779–780, 782,
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 wa

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ters as traditionally understood. In my view this case
should be remanded so that the District Court may recon
sider the evidence in light of the appropriate standard. See,
e. g., Pullman-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 fur
ther proceedings to permit the trial court to make the miss
ing 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 detri
mental 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 water
way. . . . 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

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runoff and . . . accretion along the drain and further down
stream in Auvase Creek.” Id., at 98a. And it observed
that increased runoff from the site would likely cause down
stream areas to “see an increase in possible flooding magni
tude 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 substan
tial 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 im
portant 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 re
view, 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 toward 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 re

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Stevens, J., dissenting
mand a case to an agency for decision of a matter that stat
utes 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.
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”—de
fined 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 juris
diction of the Army Corps; the question in No. 04–1384 is
whether a manmade berm separating a wetland from the ad
jacent 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 Con
gress, and that have been repeatedly enforced in case after
case, must now be revised in light of the creative criticisms

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voiced by the plurality and Justice Kennedy today. Re
jecting more than 30 years of practice by the Army Corps,
the plurality disregards the nature of the congressional dele
gation 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 tribu
taries 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 down
stream flooding by absorbing water at times of high flow.
The Corps’ resulting decision to treat these wetlands as en
compassed within the term “waters of the United States” is
a quintessential example of the Executive’s reasonable inter
pretation 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 Bay
view 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 peti
tioners filled large areas of wetlands without permits, de
spite being on full notice of the Corps’ regulatory require
ments. 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 illustra
tive. In 1988, John Rapanos asked the Michigan Depart

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ment of Natural Resources (MDNR) to inspect the site “in
order to discuss with him the feasibility of building a shop
ping 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.1 Rapanos then hired a wetland con
sultant, 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 administra
tive 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 immedi
ately. 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 navi
gable waters. The Salzburg wetlands connected to a drain
1 Pursuant to 33 U. S. C. §§ 1344(g)–(h), Michigan operates its own § 404
permitting program, subject to supervision from the Army Corps.

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that flows into a creek that flows into the navigable Kawkaw
lin 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 eco
logical functions in terms of “habitat, sediment trapping, nu
trient recycling, and flood peak diminution.” 4 Tr. 96 (Apr.
5, 1999).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 Ra
panoses 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 petition
ers in that case own a 20-acre tract of land, of which 16 acres
are wetlands, located in Macomb County a mile from Lake
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.

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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 wet
lands 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 per
mit 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 pro
vides valuable seasonal habitat for aquatic organisms
and year round habitat for terrestrial organisms. Addi
tionally, 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 wet
land, 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 cu
mulatively 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

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this wetland because it is adjacent to a tributary of tradition
ally navigable waters. 391 F. 3d 704 (CA6 2004). The So
licitor 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 in
terpret “waters of the United States” to cover all tradition
ally navigable waters; tributaries of these waters; and wet
lands 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 landown
ers 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).3
3 By contrast, we “d[id] not express any opinion” on the Corps’ addi
tional 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 780 (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 regu
lation 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 destruc
tion 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 iden
tical 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

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We held that, pursuant to our decision in Chevron,
“our review is limited to the question whether it is rea
sonable, 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 “congres
sional concern for protection of water quality and aquatic
ecosystems,” id., at 133.
Contrary to the plurality’s revisionist reading today, ante,
at 740–742, 746–747, Riverside Bayview nowhere implied
that our approval of “adjacent” wetlands was contingent
upon an understanding that “adjacent” means having a “con
tinuous surface connection” between the wetland and its
neighboring creek, ante, at 742. 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 con
cluded 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
regulation by other provisions of the regulation, namely, a combination of
§§ 323.2(a)(1) (covering traditionally navigable waters), (4) (covering tribu
taries of subsection (a)(1) waters), and (7) (covering wetlands adjacent to
subsection (a)(4) waters).

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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 adja
cent 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’ as
serted jurisdiction over wetlands had been specifically
brought to Congress’ attention in 1977, that Congress had
rejected an amendment that would have narrowed that juris
diction, 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 con
trast 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 Riv
erside Bayview, see n. 3, supra, namely, the Corps’ jurisdic
tion 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”

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and contained a few pools of “nonnavigable, isolated, intra
state waters.” 531 U. S., at 162, 166. The Corps had as
serted jurisdiction over the gravel pit under its 1986 Migra
tory 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 iso
lated pools, unlike the wetlands at issue in Riverside Bay
view, had no “significant nexus” to traditionally navigable
waters. 531 U. S., at 167. In the process, the Court distin
guished 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 pro
posals 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).4
4 As The Chief Justice observes, the Corps and the EPA initially con
sidered revising their regulations in response to SWANCC. Ante, at 757–
758 (concurring opinion). The Chief Justice neglects to mention, how
ever, 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 Re
sources 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 Jurisdic
tion, 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 Associa
tion 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 River
side 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

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Unlike SWANCC and like Riverside Bayview, the cases
before us today concern wetlands that are adjacent to “navi
gable 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 plural
ity would have it, ante, at 741—instead, they are integral to
the “chemical, physical, and biological integrity of the Na
tion’s waters,” 33 U. S. C. § 1251(a). Given that wetlands
serve these important water quality roles and given the am
biguity inherent in the phrase “waters of the United States,”
the Corps has reasonably interpreted its jurisdiction to cover
nonisolated wetlands. See 474 U. S., at 131–135.5
[Clean Water Act] jurisdiction over isolated, intrastate, non-navigable
waters”).
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 trib
utaries. E. g., United States v. Deaton, 332 F. 3d 698 (CA4 2003) (uphold
ing 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); Head
waters, 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 Fre

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This conclusion is further confirmed by Congress’ deliber
ate acquiescence in the Corps’ regulations in 1977. Id., at
136. Both Chambers conducted extensive debates about the
Corps’ regulatory jurisdiction over wetlands, rejected ef
forts 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 regu
late wetlands adjacent to ‘navigable waters,’ respondents
point us to no persuasive evidence” of congressional acquies
cence (emphasis added)).
The Corps’ exercise of jurisdiction is reasonable even
though not every wetland adjacent to a traditionally naviga
ble water or its tributary will perform all (or perhaps any)
of the water quality functions generally associated with wet
lands. 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 water
shed’s water quality. If a particular wetland is “not signifi
cantly intertwined with the ecosystem of adjacent water
ways,” then the Corps may allow its development “simply by
issuing a permit.” Ibid.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 func
mont 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).
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.

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tions, but may not do much to trap other pollutants, supra,
at 790, and n. 2, or that the wetland in No. 04–1384 keeps
excess water from Lake St. Clair but may not trap sediment,
see supra, at 790–792.
Seemingly alarmed by the costs involved, the plurality
shies away from Riverside Bayview’s recognition that juris
diction 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 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 develop
ment activity. Sunding & Zilberman 80. More significant
than the plurality’s exaggerated concern about costs, how
ever, 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.8 The importance of wetlands
7 According to the Sunding and Zilberman article cited by the plurality,
ante, at 721, for 80% of permits the mean cost is about $29,000 (with a
median cost of about $12,000). The Economics of Environmental Regula
tion by Licensing: An Assessment of Recent Changes to the Wetland Per
mitting 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 wa
ters of the United States requires a § 404 permit. Only when such fill
comes from point sources—“discernible, confined and discrete convey
ance[s]”—is a § 404 permit needed. 33 U. S. C. §§ 1362(12), (14). More
over, permits are not required for discharges from point sources engaged
in, among other things, normal farming activities; maintenance of trans
portation structures; and construction of irrigation ditches, farm roads,
forest roads, and temporary mining roads. § 1344(f).
8 Rather than defending its own antagonism to environmentalism, the
plurality counters by claiming that my dissent is “policy-laden.” Ante,
at 746. The policy considerations that have influenced my thinking are
Congress’ rather than my own. In considering whether the Corps’ inter
pretation of its jurisdiction is reasonable, I am admittedly taking into ac

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799 Cite as: 547 U. S. 715 (2006)
Stevens, J., dissenting
for water quality is hard to overstate. See, e. g., U. S.
Congress, Office of Technology Assessment, Wetlands:
Their Use and Regulation, OTA–O–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 re
charge, trapping of suspended sediment, filtering of toxic pol
lutants, and protection of fish and wildlife). See also ante,
at 777 (Kennedy, J., concurring in judgment). Unsurpris
ingly, the Corps’ approach has the overwhelming endorse
ment 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 appropriate
ness 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 partic
ular conservation measures outweigh their costs is a classic
question of public policy that should not be answered by ap
pointed judges. The fact that large investments are re
quired to finance large developments merely means that
those who are most adversely affected by the Corps’ permit
ting decisions are persons who have the ability to communi
cate 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.
count the congressional purpose of protecting the physical, chemical, and
biological integrity of our waters. See 33 U. S. C. § 1251(a); see also Chev
ron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S.
837, 863 (1984) (considering whether the agency regulation was consist
ent with “the policy concerns that motivated the [Clean Air Act’s]
enactment”).

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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 sup
port in the language and purposes of the Act or in our cases
interpreting it.” Ante, at 768 (opinion concurring in judg
ment). The impropriety of crafting these new conditions is
highlighted by the fact that no party or amicus has sug
gested either of them.9
First, ignoring the importance of preserving jurisdiction
over water beds that are periodically dry, the plurality im
poses a requirement that only tributaries with the “rela
tively permanent” presence of water fall within the Corps’
jurisdiction. Ante, at 732. 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 regu
late 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 732–
733, n. 5.10
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’ juris
diction—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.
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 732, n. 5. I will not explore the seman
tic 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

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Stevens, J., dissenting
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 732–733,
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, flow
ing on the earth’ ”). From this, the plurality somehow de
duces that streams can never be intermittent or ephemeral
(i. e., flowing for only part of the year). Ante, at 732–
734, and nn. 5–6. But common sense and common usage
demonstrate that intermittent streams, like perennial
streams, are still streams.11 See, e. g., U. S. Dept. of Inte
rior, U. S. Geological Survey, Topographic Map Symbols 3
(2005), http://erg.usgs.gov/isb/pubs/ booklets/symbols/ (iden
tifying 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 “intermit
tent” with “stream”). Indeed, we ourselves have used the
term “intermittent stream” as far back as 1932. Harrison
ville v. W. S. Dickey Clay Mfg. Co., 289 U. S. 334, 335 (1933).
Needless to say, Justice Brandeis’ use of the term in a unani
mous opinion should not be dismissed as merely a “useful
oxymor[on],” ante, at 733, n. 6 (plurality opinion).
itself, the plurality leaves litigants without guidance as to where the line
it draws between “relatively permanent” and “intermittent” lies.
11 Indeed, in the 1977 debate over whether to restrict the scope of the
Corps’ regulatory power, Senator Bentsen recognized that the Corps’ ju
risdiction “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 com
piled for the Senate Committee on Environment and Public Works by the
Library of Congress), Ser. No. 95–14, p. 903 (1978). His proposed amend
ment to restrict this jurisdiction failed. Id., at 947.

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The plurality attempts to bolster its arbitrary jurisdic
tional 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 defini
tion of “point source” in 33 U. S. C. § 1362(14)—has no con
ceivable 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.12 The
second provision is § 1251(b), which announces a congres
sional 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
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 736, 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 plu
rality’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 739, 742 (plurality opinion) (using “channel” with reference
to both intermittent and relatively permanent waters); PUD No. 1 of Jef
ferson Cty. v. Washington Dept. of Ecology, 511 U. S. 700, 709 (1994) (de
scribing 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.

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regulatory jurisdiction, the States may run their own § 404
programs. §§ 1344(g)–(h). As modified, § 1251(b) specifi
cally recognizes this role for the States as part of their pri
mary 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 ad
ditions), 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, ante,
at 386–387. 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 in
termittent streams. As we have recognized, however, Con
gress found it “ ‘essential that discharge of pollutants be con
trolled 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 tradition
ally navigable waters and play important roles in the water
shed, such as keeping water out of the tributaries or absorb
ing water from the tributaries. “There is no constitutional
reason why Congress cannot, under the commerce power,

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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 fundamen
tal 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 rewrit
ing’ 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 pro
gram of water pollution regulation,” and “[t]he most casual
perusal of the legislative history demonstrates that . . . views
on the comprehensive nature of the legislation were practi
cally universal.” Id., at 318, and n. 12; see also 531 U. S.,
at 177–181 (Stevens, J., dissenting). The Corps has con
cluded 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. Inter
mittent 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 condi
tions in wetlands environments, the plurality imposes a sepa
rate requirement that “the wetland has a continuous surface
connection” with its abutting waterway such that it is “diffi
cult to determine where the ‘water’ ends and the ‘wetland’
begins.” Ante, at 742. An “intermittent, physically re

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mote hydrologic connection” between the wetland and other
waters is not enough. Ibid. Under this view, wetlands
that border traditionally navigable waters or their tributar
ies 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 “ ‘ad
jacent to’ ” other waters. Ibid. 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 wet
lands” 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 742. 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 Adja
cent 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 ques
tion 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

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other waters of the United States by man-made dikes or bar
riers, natural river berms, beach dunes and the like are ‘adja
cent 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 func
tions, this is a matter for the Corps to evaluate in its permit
ting 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 connec
tion required by the plurality today. See supra, at 793; see
also ante, at 772–774 (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 be
fore they actually enter the “waters of the United States.”
Ante, at 742–746. 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 726–729.
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 plural
ity claims that there is a practical difference, asserting that
dredged and fill material “does not normally wash down

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stream.” Ante, at 744. 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 pro
tecting fish, see 33 U. S. C. § 1251(a)(2); S. D. Warren Co.,
ante, at 385–386, 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 Ameri
can Rivers et al. as Amici Curiae 14 (observing that anadro
mous 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 require
ment, 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 in
formed our reading of the [Clean Water Act] in Riverside
Bayview.” 531 U. S., at 167. Because Riverside Bayview

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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’ jurisdic
tion 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 tribu
taries 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 re
leasing 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 779 (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
discernible relationship to any aspect of downstream water
quality, I am skeptical. And even given Justice Kenne
dy’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 recog
nizes that the records in both cases contain evidence that
“should permit the establishment of a significant nexus,”

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ante, at 783; see also ante, at 784, 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 wish
ing to fill wetlands adjacent to ephemeral or intermittent
tributaries of traditionally navigable waters will have no cer
tain 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 proc
essing 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 widespread recognition—based on
events like the 1969 burning of the Cuyahoga River in Cleve
land—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 location 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

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the Executive, the congressional acquiescence in the Execu
tive’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 respect
fully dissent from the decision of five Members of this Court
to vacate and remand. I close, however, by noting an un
usual 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 man
date. That prior practice has, on occasion, made it neces
sary for Justices to join a judgment that did not conform to
their own views.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 de
fine 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.14
13 See, e. g., Screws v. United States, 325 U. S. 91, 131–134 (1945) (Rut
ledge, 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).
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.

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Breyer, J., dissenting
Justice Breyer, dissenting.
In my view, the authority of the Army Corps of Engineers
under the Clean Water Act extends to the limits of congres
sional power to regulate interstate commerce. See Solid
Waste Agency of Northern Cook Cty. v. Army Corps of En
gineers, 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’ juris
diction, 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 enforc
ing 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 779 (Kennedy, J., concurring in judg
ment) (“[T]he Corps’ jurisdiction over wetlands depends
upon the existence of a significant nexus between the wet
lands 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 Re
sources 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 judg

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ments that lie at the heart of the present cases (subject to
deferential judicial review). In the absence of updated reg
ulations, 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.