discussion of the Clean Water Act's jurisdiction over interstate
waters. Finally, the text and focus of the rule's significant nexus
standard are derived from and designed to advance the text of the first
sentence in the statute setting forth the Act's sole statutory
objective: ``to restore and maintain the chemical, physical, and
biological integrity of the Nation's waters.'' See 33 U.S.C. 1251(a).
    As noted above, a statute must be interpreted in light of the
purposes Congress sought to achieve. See, e.g., Gen. Dynamics Land
Sys., Inc. v. Cline, 540 U.S. 581 (2004). Thus, the agencies must
consider the objective of the Clean Water Act to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters'' in interpreting the scope of the statutory term ``waters of
the United States.'' See 33 U.S.C. 1251(a). This consideration is
particularly important where, as here, Congress used specific language
in the definitions in order to meet the objective of the Act and the
definition of ``waters of the United States'' is fundamental to meeting
the objective of the Act. See section IV.A.2 of this preamble. Congress
was focused on water quality when it enacted the Clean Water Act and
established the Act's objective, and the significant nexus standard is
derived from the objective of the Act to protect the water quality of
the paragraph (a)(1) waters. The significant nexus standard is
consistent with foundational scientific understanding about aquatic
ecosystems: waters can significantly affect the chemical, physical, and
biological integrity of traditional navigable waters, the territorial
seas, and interstate waters. Therefore, assessing the effects that
waters have on paragraph (a)(1) waters when considered, alone or in
combination with other similarly situated waters in a region, is the
best means of identifying those waters that must be protected in order
to advance the objective of the Clean Water Act.
    The agencies have also considered the statute as a whole in
construing the scope of ``waters of the United States.'' The
comprehensive nature of the Clean Water Act and its pronounced change
in approach from precursor water protection statutes is evident
throughout the statute, and the agencies have considered the text of
those provisions in defining ``waters of the United States.'' One of
the Clean Water Act's principal tools in protecting the integrity of
the nation's waters is section 301(a), which prohibits ``the discharge
of any pollutant by any person'' without a permit or other
authorization under the Act. Other substantive provisions of the Clean
Water Act that use the term ``navigable waters'' and are designed to
meet the statutory objective include the section 402 permit program,
the section 404 dredged and fill permit program, the section 311 oil
spill prevention and response program, the section 303 water quality
standards and total maximum daily load programs, and the section 401
Tribal and State water quality certification process. Each of these
programs is designed to protect water quality and, therefore, further
the objective of the Clean Water Act. The agencies have also carefully
considered the Act's policies regarding the responsibilities and rights
of Tribes and States. See section IV.A.3.b of this preamble. The
agencies have thus construed ``waters of the United States'' to include
waters that meet the significant nexus standard based on the text of
the Clean Water Act's interlocking provisions designed to restore and
maintain the chemical, physical, and biological integrity of the
nation's waters.
    A significant nexus analysis is also consistent with the framework
scientists apply to assess a river system--examining how the components
of the system (e.g., wetlands or tributaries), alone or in the
aggregate (in combination), in a region, contribute and connect to a
river (significantly affect the chemical, physical, or biological
integrity of paragraph (a)(1) waters). Indeed, the significant nexus
standard in this rule reflects the analysis in the Science Report by
describing the components of a river system and watershed; the types of
chemical, physical, and biological connections that link those
components; the factors that influence connectivity and associated
effects at various temporal and spatial scales; and methods for
assessing downstream effects. The structure and function of rivers are
highly dependent on the constituent materials stored in and transported
through them. Most of these materials originate from either the
upstream river network or other components of the river system,
including wetlands, and then are transported to the river by water
movement or other mechanisms. Further, the significant nexus standard
is supported by the Science Report's discussion of connectivity, a
foundational concept in hydrology and freshwater and marine ecology.
See also Technical Support Document sections I.A.ii and III.E.
    Connectivity is the degree to which components of a system are
joined or linked by various transport mechanisms and is determined by
the characteristics of both the physical landscape and the biota of the
specific system. Connectivity serves to demonstrate the ``nexus''
between upstream waterbodies and traditional navigable waters, the
territorial seas, or interstate waters, and variations in the degree of
connectivity influence the range of functions provided by streams,
wetlands, and open waters and are critical to the integrity and
sustainability of paragraph (a)(1) waters. For example, connections
with low values of one descriptor can have important downstream effects
when considered in context of other types of connections (e.g., a
stream with low-duration flow during a flash flood can transfer large
volumes of water and woody debris downstream, affecting the integrity
of a paragraph (a)(1) water). Indeed, the seasonal or longer-term
absence of surface connections can provide numerous functions that
contribute to the chemical, physical, and biological integrity of
paragraph (a)(1) waters: these wetlands can attenuate stormflow;
increase baseflow; be a source of carbon and organic matter; and be a
sink for sediment, nitrate, and other constituents that degrade water
quality. While the scientific literature does not use the term
``significant'' in the same manner used by the Supreme Court, the
literature does provide information on the strength of upstream effects
on the chemical, physical, and biological functioning of the downstream
waterbodies. The analysis in the literature permits the agencies to
judge when an effect is significant such that a water, either alone or
in combination with similar waters, should be protected by the Clean
Water Act in order to meet the objective of the Act. The Science Report
presents evidence of connections for various categories of waters,
evaluated singly or in combination, which affect downstream waters and
the strength of those effects. The

connections and mechanisms discussed in the Science Report include
transport of physical materials and chemicals such as water, wood,
sediment, nutrients, pesticides, and metals (e.g., mercury); functions
that streams, wetlands, and open waters perform, such as storing and
cleansing water; and movement of organisms. Again, the significant
nexus standard, under which waters are assessed alone or in combination
for the functions they provide to paragraph (a)(1) waters, is
consistent with the foundational scientific framework and concepts of
hydrology.
    The agencies' use of scientific principles to determine the scope
of ``waters of the United States'' is consistent with the Supreme
Court's approach in Maui. The Court in that case also looked to
scientific principles to inform its interpretation of the Clean Water
Act's jurisdictional scope, noting: ``[m]uch water pollution does not
come from a readily identifiable source. Rainwater, for example, can
carry pollutants (say, as might otherwise collect on a roadway); it can
pollute groundwater, and pollution collected by unchanneled rainwater
runoff is not ordinarily considered point source pollution.'' Maui, 140
S. Ct. at 1471 (citing the definition of ``water pollution'' from 3 Van
Nostrand's Scientific Encyclopedia, at 5801). The Court then enumerated
a series of factors, many of which are scientifically based, relevant
to determining whether a discharge is jurisdictional under the Clean
Water Act, including the nature of the material through which the
pollutant travels and the extent to which the pollutant is diluted or
chemically changed as it travels. Id. at 1476-77.
    In carefully considering the text and objective of the Clean Water
Act and the best available science, this rule's incorporation of the
significant nexus standard is also consistent with the legislative
history of the Clean Water Act. The Supreme Court has noted that ``some
Members of this Court have consulted legislative history when
interpreting ambiguous statutory language.'' Bostock v. Clayton Cnty.,
Ga., 140 S. Ct. 1731, 1749 (2020) (emphasis in original). In Bostock,
the Court stated further that ``while legislative history can never
defeat unambiguous statutory text, historical sources can be useful for
a different purpose: Because the law's ordinary meaning at the time of
enactment usually governs, we must be sensitive to the possibility a
statutory term that means one thing today or in one context might have
meant something else at the time of its adoption or might mean
something different in another context. And we must be attuned to the
possibility that a statutory phrase ordinarily bears a different
meaning than the terms do when viewed individually or literally. To
ferret out such shifts in linguistic usage or subtle distinctions
between literal and ordinary meaning, this Court has sometimes
consulted the understandings of the law's drafters.'' Id. at 1750.
    Bills introduced in 1972 in both the House of Representatives and
the Senate defined ``navigable waters'' as ``the navigable waters of
the United States.'' See 2 Environmental Policy Div., Library of
Congress, Legislative History of the Water Pollution Control Act
Amendments of 1972 at 1069, 1698 (1973). The House and Senate
Committees, however, expressed concern that the definition might be
given an unduly narrow reading. Thus, the House Report observed: ``One
term that the Committee was reluctant to define was the term `navigable
waters.' The reluctance was based on the fear that any interpretation
would be read narrowly. However, this is not the Committee's intent.
The Committee fully intends that the term `navigable waters' be given
the broadest possible constitutional interpretation unencumbered by
agency determinations which have been made or may be made for
administrative purposes.'' H.R. Rep. No. 92-911, at 131 (1972).
    The Senate Report stated that ``[t]hrough a narrow interpretation
of the definition of interstate waters the implementation [of the] 1965
Act was severely limited. Water moves in hydrologic cycles and it is
essential that discharge of pollutants be controlled at the source.''
S. Rep. No. 92-414, at 77 (1971). The Conference Committee deleted the
word ``navigable'' from the definition of ``navigable waters,'' broadly
defining the term to include ``the waters of the United States.'' The
Conference Report explained that the definition was intended to
repudiate earlier limits on the reach of Federal water pollution
efforts: ``The conferees fully intend that the term `navigable waters'
be given the broadest possible constitutional interpretation
unencumbered by agency determinations which have been made or may be
made for administrative purposes.'' S. Conf. Rep. No. 92-1236, at 144
(1972). The significant nexus standard thus fulfills Congress's intent
that the scope of the term ``navigable waters'' be broader than the
limitations of earlier water pollution control statutes and agency
determinations under them (section 10 waters and their tributaries, for
example, under the Rivers and Harbors Act of 1899). And, because the
significant nexus standard is focused on protecting waters to meet the
objective of the Act, it also comports with congressional intent.
    The significant nexus standard is also consistent with prior
Supreme Court decisions and with every circuit decision that has
gleaned a rule of law from that precedent. For example, in Riverside
Bayview, the Court deferred to the agencies' interpretation: ``In view
of the breadth of Federal regulatory authority contemplated by the Act
itself and the inherent difficulties of defining precise bounds to
regulable waters, the Corps' ecological judgment about the relationship
between waters and their adjacent wetlands provides an adequate basis
for a legal judgment that adjacent wetlands may be defined as waters
under the Act.'' 474 U.S. at 134. Indeed, the Court in Riverside
Bayview concluded that ``significant effects'' is the relevant basis
for asserting jurisdiction over adjacent wetlands: ``If it is
reasonable for the Corps to conclude that in the majority of cases,
adjacent wetlands have significant effects on water quality and the
aquatic ecosystem, its definition can stand.'' Id. at 135 n.9. In
Rapanos, Justice Kennedy--referencing the Court in Riverside Bayview--
stated that ``the Court indicated that `the term ``navigable'' as used
in the Act is of limited import,' [and] it relied, in upholding
jurisdiction, on the Corps' judgment that `wetlands adjacent to lakes,
rivers, streams, and other bodies of water may function as integral
parts of the aquatic environment even when the moisture creating the
wetlands does not find its source in the adjacent bodies of water.' ''
547 U.S. at 779 (Kennedy, J., concurring in the judgment) (citing
Riverside Bayview, 474 U.S. at 133, 135). ``The implication,'' Justice
Kennedy observed, ``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.'' Rapanos, 547 U.S. at 779 (emphasis
added); see also id. at 780 (``[W]etlands' ecological functions vis-
[aacute]-vis other covered waters are the basis for the Corps'
regulation of them.''). The Court in SWANCC also characterized its
decision in Riverside Bayview as informed by the ``significant nexus
between the wetlands and `navigable waters.' '' 531 U.S. at 167.
    In Rapanos, Justice Kennedy reasoned that Riverside Bayview and
SWANCC

``establish the framework for'' determining whether an assertion of
regulatory jurisdiction constitutes a reasonable interpretation of
``navigable waters,'' finding that ``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,'' and ``[a]bsent a significant nexus,
jurisdiction under the Act is lacking.'' 547 U.S. at 767. Justice
Kennedy also identified many of the same valuable wetland functions as
the Science Report: ``Important public interests are served by the
Clean Water Act in general and by the protection of wetlands in
particular. To give just one example, amici here have noted that
nutrient-rich runoff from the Mississippi River has created a hypoxic,
or oxygen-depleted, `dead zone' in the Gulf of Mexico that at times
approaches the size of Massachusetts and New Jersey. Scientific
evidence indicates that wetlands play a critical role in controlling
and filtering runoff'' Id. at 777 (citing Brief for Association of
State Wetland Managers et al. 21-23; Brief for Environmental Law
Institute 23; OTA 43, 48-52; R. Tiner, In Search of Swampland: A
Wetland Sourcebook and Field Guide 93-95 (2d ed. 2005); Whitmire &
Hamilton, Rapid Removal of Nitrate and Sulfate in Freshwater Wetland
Sediments, 34 J. Env. Quality 2062 (2005)).
    The agencies are mindful of the Supreme Court's decision in SWANCC
regarding the specific Commerce Clause authority Congress was
exercising in enacting the Clean Water Act--``its traditional
jurisdiction over waters that were or had been navigable in fact or
which could reasonably be so made''--and the Court's guidance on
avoiding an administrative interpretation of a statute that invokes the
outer limits of Congress's power. 531 U.S. at 172; see also id. (``[W]e
expect a clear indication that Congress intended that result.''). With
respect to section 404 authority over an abandoned sand and gravel pit
based simply on whether it was used by migratory birds (the ``Migratory
Bird Rule''), the SWANCC Court concluded that there was not a clear
statement from Congress. Id. at 174. By placing traditional navigable
waters, the territorial seas, and interstate waters at the center of
the agencies' jurisdiction and covering additional waters only where
those waters significantly affect (a)(1) waters, this rule reflects the
Court's guidance. Further, in construing the statute in this rule, the
agencies have not only eschewed the ``Migratory Bird Rule,'' they have
deleted the provisions in the 1986 regulations that authorized
assertions of jurisdiction under broader Commerce Clause authority and
replaced them with the relatively permanent and significant nexus
standards.
    Indeed, the provisions in the 1986 regulations authorized
assertions of jurisdiction far more broadly than under the relatively
permanent standard and significant nexus standard in this rule. First,
the regulatory text authorized the assertion of jurisdiction over
``[a]ll other waters such as intrastate lakes, rivers, streams
(including intermittent streams), mudflats, sandflats, wetlands,
sloughs, prairie potholes, wet meadows, playa lakes, or natural ponds,
the use, degradation or destruction of which could affect interstate or
foreign commerce including any such waters: Which are or could be used
by interstate or foreign travelers for recreational or other purposes;
or From which fish or shellfish are or could be taken and sold in
interstate or foreign commerce; or Which are used or could be used for
industrial purposes by industries in interstate commerce.'' 33 CFR
328.3(a)(3) (2014). This regulatory text was based on all three
categories of activity that Congress may regulate using its Commerce
Clause authority: (1) the channels of interstate commerce; (2) persons
or things in interstate commerce; and (3) activities that substantially
affect interstate commerce. See United States v. Lopez, 514 U.S. 549,
558-59 (1995). This approach thus overall was a far broader definition
of ``waters of the United States'' than this rule, which recognizes
that the Supreme Court in SWANCC held that Congress was not using all
aspects of its Commerce Clause authority. Moreover, as discussed by the
Court in SWANCC, the agencies stated in the preamble to the 1986
regulations that ``waters of the United States'' at 33 CFR 328.3(a)(3)
also included waters that ``are or would be used as habitat by birds
protected by Migratory Bird Treaties; . . . [that] are or would be used
as habitat by other migratory birds which cross state lines; . . .
[that] are or would be used as habitat for endangered species; or . . .
[waters] [u]sed to irrigate crops sold in interstate commerce.'' 51 FR
41206, 41217 (November 13, 1986). This is the 1986 preamble language
that became known as the ``Migratory Bird Rule'' and clearly
established a far greater scope of ``waters of the United States'' than
this rule, as migratory birds use waters large and small all over the
United States with no connection to a traditional navigable water, the
territorial seas, or an interstate water.
    The agencies also have carefully amended other provisions of the
1986 regulations not only to add the relatively permanent standard and
the significant nexus standard as limitations on the scope of ``waters
of the United States'' but to add additional limitations where the
agencies were concerned assertions of jurisdiction could push the
limits of the congressional authority granted to the agencies or
constitutional limits. For example, in a change from the 1986
regulations, tributaries to intrastate lakes and ponds, streams, and
wetlands that do not fall within other categories of the rule
(paragraph (a)(5) waters in this rule, which are analogous to the
``other waters'' provision of the 1986 regulations) do not qualify as
tributaries under this rule, nor do wetlands adjacent to such waters.
As set forth in this rule, the relatively permanent standard and the
significant nexus standard allow the agencies to fulfill the statute
and Congress's clearly stated objective, while being carefully crafted
to fall well within the authority granted to the agencies by Congress
and to Congress by the Constitution. As noted above, the SWANCC Court
itself viewed ``significant nexus'' as the touchstone for determining
the scope of ``waters of the United States'' in its decision in
Riverside Bayview, concluding the decision was informed by the
``significant nexus between the wetlands and `navigable waters.' '' 531
U.S. at 167. The agencies agree with the analysis of Justice Kennedy,
who explicitly addressed these constitutional concerns in Rapanos,
stating: ``In SWANCC, by interpreting the Act to require a significant
nexus with navigable waters, the Court avoided applications--those
involving waters without a significant nexus--that appeared likely, as
a category, to raise constitutional difficulties and federalism
concerns.'' 547 U.S. at 776. Moreover, the rule is consistent with
decades of interpretation and implementation undisturbed by Congress.
    Moreover, the SWANCC Court noted that the statement in the
Conference Report for the Clean Water Act that the conferees ``intend
that the term `navigable waters' be given the broadest possible
constitutional interpretation,'' S. Conf. Rep. No. 92-1236, at 144
(1972), signifies Congress's intent with respect to its exertion of its
commerce power over navigation. As the numerous Supreme Court decisions
discussed above have found, Congress enacted the Clean Water Act to
establish a comprehensive Federal law protecting

water quality. The agencies' construction of the statute must also give
effect to the clearly stated objective of the Act and all the
provisions of the Act designed to achieve that objective. See section
IV.A.2 of this preamble. Thus, while the agencies must be mindful that
Congress was utilizing an aspect of its commerce power, they must be
similarly mindful that Congress intended to fully exercise that
authority in order to comprehensively address water pollution. The
agencies have concluded that the legislative history concerning the
intent of Congress regarding the scope of the Clean Water Act's
protections under its power over navigation confirms the
appropriateness of the agencies' construction of the Clean Water Act in
this rule. This rule ensures that waters, which either alone or in
combination significantly affect the integrity of traditional navigable
waters, the territorial seas, or interstate waters, are protected by
the Clean Water Act, and thus this rule carefully balances the limits
on Congress's authority and on the agencies' authority under the Act,
with congressional intent to comprehensively protect water quality and
to delegate the authority to do so to the agencies.
    Finally, the Supreme Court has long held that authority over
traditional navigable waters is not limited to either protection of
navigation or authority over only the traditional navigable water.
Rather, ``the authority of the United States is the regulation of
commerce on its waters . . . [f]lood protection, watershed development,
[and] recovery of the cost of improvements through utilization of power
are likewise parts of commerce control.'' United States v. Appalachian
Electric Power Co., 311 U.S. 377, 426 (1940); see also 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 part in
flood control on its tributaries. . . . [T]he exercise of the granted
power of Congress to regulate interstate commerce may be aided by
appropriate and needful control of activities and agencies which,
though intrastate, affect that commerce.''). As the United States Court
of Appeals for the Sixth Circuit observed after the 1972 enactment of
the Clean Water Act: ``It would, of course, make a mockery of
[Congress's] powers if its authority to control pollution was limited
to the bed of the navigable stream itself. The tributaries which join
to form the river could then be used as open sewers as far as federal
regulation was concerned. The navigable part of the river could become
a mere conduit for upstream waste.'' United States v. Ashland Oil &
Transp. Co., 504 F.2d 1317, 1326 (6th Cir. 1974). The significant nexus
standard included in this rule ensures that the definition of ``waters
of the United States'' remains within the bounds of the Clean Water Act
and addresses the concerns raised by the Court in SWANCC while also
fulfilling the directive of Congress in enacting the Clean Water Act.
ii. The Relatively Permanent Standard Is Administratively Useful, But
Exclusive Reliance on the Standard for All Determinations Is
Inconsistent With the Objective of the Act
    The agencies conclude that Federal protection is appropriate where
a water meets the relatively permanent standard: waters that are
relatively permanent, standing or continuously flowing waters connected
to paragraph (a)(1) waters, and waters with a continuous surface
connection to such relatively permanent waters or to paragraph (a)(1)
waters. Waters that meet this standard are a subset of the ``waters of
the United States'' because they will virtually always significantly
affect traditional navigable waters, the territorial seas, or
interstate waters and therefore properly fall within the Clean Water
Act's scope. However, limiting the definition of ``waters of the United
States'' to the relatively permanent standard on its own would be
inconsistent with the Act's text and objective and runs counter to
scientific principles. As discussed further below, the agencies have
included the relatively permanent standard in this rule because it
provides efficiencies and additional clarity for regulators and the
public.
    Waters that meet the relatively permanent standard are within the
scope of the Clean Water Act because scientific evidence supports the
conclusion that tributaries of paragraph (a)(1) waters with relatively
permanent, standing or continuously flowing water perform important
functions that either individually, or cumulatively with similarly
situated waters in the region, have significant effects on the
chemical, physical, or biological integrity of paragraph (a)(1) waters.
The same is true of adjacent wetlands and relatively permanent open
waters with continuous surface connections to tributaries that meet the
relatively permanent standard. See Technical Support Document sections
III.A, III.B, and III.D. Tributaries that meet the relatively permanent
standard contribute consistent flow to paragraph (a)(1) waters and,
with that flow, export nutrients, sediment, food resources,
contaminants, and other materials that can both positively (e.g., by
contributing to downstream baseflow, providing food for aquatic
species, and contributing to downstream aquatic habitat) and negatively
(e.g., by exporting too much sediment, runoff, or nutrients or
exporting pollutants) affect the integrity of those paragraph (a)(1)
waters. In addition, wetlands with a continuous surface connection to
tributaries that meet the relatively permanent standard can and do
attenuate floodwaters, trap sediment, and process and transform
nutrients that might otherwise reach traditional navigable waters, the
territorial seas, or interstate waters. If the agencies assessed waters
that meet the relatively permanent standard (e.g., tributaries that
meet the relatively permanent standard or adjacent wetlands with a
continuous surface connection to such tributaries) they would virtually
always find evidence of strong factors, particularly hydrologic factors
like flow frequency and duration, that lead to strong connections and
associated effects on paragraph (a)(1) waters. Therefore, waters that
meet the relatively permanent standard will virtually always meet the
significant nexus standard.
    The relatively permanent standard is useful for the agencies and
the public because it generally requires less information gathering and
assessment than the significant nexus standard. The significant nexus
standard requires evaluating whether waters, alone or in combination,
significantly affect the chemical, physical, or biological integrity of
paragraph (a)(1) waters, i.e., traditional navigable waters, the
territorial seas, and interstate waters. Such an assessment requires
considering the presence of functions for one or more subject waters
and evaluating the strength of their effects on paragraph (a)(1)
waters. In contrast, the relatively permanent standard has a more
limited focus that requires considering the flow of a tributary or
considering the surface connection between an adjacent wetland or open
water and a relatively permanent covered water. As such, while both the
significant nexus and relatively permanent standards require case-
specific, fact-based inquiries before determining whether a water meets
the definition of ``waters of the United States,'' the relatively
permanent standard will generally require less

assessment and thus can result in administrative efficiencies.
    Standing alone as the sole test for Clean Water Act jurisdiction,
however, the relatively permanent standard has no basis in the text of
the statute and is contrary to the statute. Rather than a careful
consideration of the Clean Water Act's specialized definitions in light
of the objective of the Act, the standard's apparent exclusion of major
categories of waters from the protections of the Clean Water Act,
specifically with respect to tributaries that are not relatively
permanent and adjacent wetlands that do not have a continuous surface
connection to such relatively permanent waters or to paragraph (a)(1)
waters, is inconsistent with the Act's text and objective. In addition,
the relatively permanent standard used alone runs counter to the
science demonstrating how other categories of waters can affect the
integrity of downstream waters, including traditional navigable waters,
the territorial seas, and interstate waters. For example, many
tributaries that flow for only a short duration in direct response to
precipitation, and thus do not meet the relatively permanent standard,
are regular and direct sources of freshwater for the sparse traditional
navigable waters in the arid Southwest, such as portions of the Gila
River. In addition, many adjacent wetlands do not have a continuous
surface connection to jurisdictional waters but provide numerous flood
protection and water quality benefits to traditional navigable waters,
such as wetlands behind the extensive levee systems along the
Mississippi River.
    As discussed in section IV.A.2.c of this preamble and sections
III.A.v and III.B of the Technical Support Document, there is
overwhelming scientific information demonstrating the effects ephemeral
streams can have on downstream waters and the effects wetlands can have
on downstream waters when they do not have a continuous surface
connection. The science is clear that aggregate effects of ephemeral
streams ``can have substantial consequences on the integrity of the
downstream waters'' and that the evidence of such downstream effects is
``strong and compelling.'' Science Report at 6-10, 6-13. The SAB review
of the draft Science Report explained that ephemeral streams ``are no
less important to the integrity of the downgradient waters'' than
perennial or intermittent streams.\60\ There is thus no scientific
basis for excluding waters simply because they are not relatively
permanent.
---------------------------------------------------------------------------

    \60\ Letter from SAB to Gina McCarthy, Administrator, EPA
(October 17, 2014) (``2014 SAB Review'') at 22-23, 54 fig. 3.
---------------------------------------------------------------------------

    The science is also clear that wetlands may significantly affect
paragraph (a)(1) waters when they have other types of surface or
hydrologic connections, such as wetlands that overflow across uplands
via sheetflow and flood jurisdictional waters or wetlands with less
frequent surface water connections; wetlands with shallow subsurface
connections to other protected waters; wetlands behind a natural berm,
a beach dune, a manmade levee, or the like; or other wetlands proximate
to jurisdictional waters. Such wetlands provide a number of functions,
including water storage that can help reduce downstream flooding;
recharging groundwater that contributes to baseflow of paragraph (a)(1)
waters; improving water quality in paragraph (a)(1) waters through
processes that remove, store, or transform pollutants such as nitrogen,
phosphorus, and metals; and serving as unique and important habitats
including for aquatic species that also utilize paragraph (a)(1)
waters. See, e.g., Science Report at 4-20 to 4-38.
    The agencies have also concluded that there is no basis in the text
of the statute to exclude waters from Clean Water Act jurisdiction
solely because they do not meet the relatively permanent standard. As
discussed in section IV.A.2.a of this preamble, the objective of the
Clean Water Act is to restore and maintain the water quality of the
nation's waters. The phrase ``waters of the United States'' is by its
terms expansive and not expressly limited to relatively permanent,
standing or continuously flowing bodies of water, or to wetlands with a
continuous surface connection. The imposition of such limitations would
disregard the science demonstrating the effects of upstream waters and
wetlands on downstream paragraph (a)(1) waters. Taking science into
account, the agencies agree with Justice Kennedy that the Clean Water
Act intends to protect waters that do not meet the relatively permanent
standard, where such waters have a significant nexus to a paragraph
(a)(1) water. Rapanos, 547 U.S. at 773-74 (Kennedy, J., concurring in
the judgment) (``Needless to say, a continuous connection is not
necessary for moisture in wetlands to result from flooding--the
connection might well exist only during floods.''); see also id. at 775
(``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 wetlands will instead flow
out to major waterways. With these concerns in mind, the Corps'
definition of adjacency is a reasonable one, for it may be the absence
of an interchange of waters prior to the dredge and fill activity that
makes protection of the wetlands critical to the statutory scheme.'').
    The agencies have concluded that there is no sound basis in the
text of the statute to exclude tributaries solely on the basis that
they are not relatively permanent, standing or continuously flowing
bodies of water from the Clean Water Act. In interpreting the Clean
Water Act to be limited in such a manner, the Rapanos plurality relied
on a strained reading of the Act that is inconsistent with the text of
the statute--including the statute's stated objective--the structure of
the statute, the statutory history, and Supreme Court precedent
interpreting the Clean Water Act.
    First, the plurality stated that because one entry in a dictionary
defines ``waters'' to mean ``water `[a]s found in streams and bodies
forming geographical features such as oceans, rivers, [and] lakes,' or
`the flowing or moving masses, as of waves or floods, making up such
streams or bodies,' '' Rapanos, 547 U.S. at 732 (quoting Webster's New
International Dictionary 2882 (2d ed. 1954) (hereinafter, ``Webster's
Second'')), the phrase ``navigable waters'' permits Corps and EPA to
assert jurisdiction only over ``relatively permanent, standing or
flowing bodies of water.'' Rapanos, 547 U.S. at 732. The plurality
leans heavily on the fact that Congress defined ``navigable waters'' as
``the waters of the United States.'' 33 U.S.C. 1362(7) (emphasis
added). But the article ``the'' and plural ``waters'' cannot bear this
weight. Congress used the term ``the waters'' throughout the Clean
Water Act and in usages where it would be illogical to swap in the
plurality's preferred definition. For example, throughout the Act,
Congress frequently refers to ``the waters of the contiguous zone'' and
even ``the waters of the territorial seas, the contiguous zone, and the
oceans.'' 33 U.S.C. 1343(a), (c) (emphasis added). Congress is not
making a careful distinction between some of ``the waters'' of the
contiguous zone and other waters of the contiguous zone based on a
dictionary definition. Nor did Congress intend to single out some
waters of the Great Lakes when it instructed the Administrator to
``conduct research and technical development work, and make studies,
with respect to the quality of the waters of the Great Lakes.'' 33
U.S.C. 1254(f) (emphasis added).

    The plurality relied on one particular dictionary definition to
limit the scope of the ``waters of the United States'' in a way that is
neither compelled by, nor consistent with, the text of the statute. The
plurality selected a dictionary, Webster's Second that was not even the
most recent edition as of passage of the Clean Water Act, and thus not
as reflective of common usage, and then selected a preferred definition
within that dictionary. See Rapanos, 547 U.S. at 732. Webster's Second
does not have a separate entry for ``waters'' (plural), so the
plurality relied on its entry for ``water'' (singular) and within that
skipped over several more apt definitions to reach its preferred one.
The first definition of ``water'' within Webster's Second (1.a. of the
definition) is ``[t]he liquid which descends from the clouds in rain
and which forms rivers, lakes, seas, etc.,'' a definition that is
substantially broader than the one chosen by the plurality. The
plurality's preferred definition, ``water as found in streams and
bodies forming geographical features such as oceans, rivers, and
lakes,'' is halfway down the column, definition 2.c. Moreover, the
definition of ``waters,'' plural, in the most contemporaneous
Webster's, was also substantially broader, providing the following
definition: ``the water occupying or flowing in a particular bed.''
Webster's Third New Intl. (1966). Even taking the plurality's preferred
definition at face value, it does not support the relatively permanent
standard. That definition includes ``water as found in streams.'' The
plurality concluded that the streams referred to in the definition must
be relatively permanent and thereby concluded that the ``waters of the
United States'' do not include intermittent and ephemeral streams
(although the plurality did not use those terms in the scientific sense
and added caveats to its stated textual reading of the statute--stating
that ``relatively permanent'' does not necessarily exclude waters
``that might dry up in extraordinary circumstances, such as drought''
or ``seasonal rivers, which contain continuous flow during some months
of the year but no flow during dry months''). Rapanos, 547 U.S. at 732
n.5 (emphasis in original). Intermittent and ephemeral streams are, of
course, ``streams''--as they are defined in the dictionary, understood
in common parlance, and defined by scientists.
    The agencies thus agree with Justice Kennedy that the limitations
the plurality imposes on the Clean Water Act ``are without support in
the language and purposes of the Act or in our cases interpreting it.''
Rapanos, 547 U.S. at 768. The agencies also agree that a permanent
standing water or continuous flow requirement ``makes little practical
sense in a statute concerned with downstream water quality.'' Id. at
769. And, as discussed above, ``a full reading of the dictionary
definition precludes the plurality's emphasis on permanence: The term
`waters' may mean `flood or inundation,' events that are impermanent by
definition;'' it follows that ``the Corps can reasonably interpret the
Act to cover the paths of such impermanent streams.'' Id. at 770
(quoting Webster's Second 2882).
    The agencies also have concluded that Riverside Bayview does not
support the plurality's standard for tributaries. As Justice Kennedy
stated: ``To be sure, the Court there compared wetlands to `rivers,
streams, and other hydrographic features more conventionally
identifiable as ` ``waters.'' ' Rapanos, 547 U.S. at 771 (citing
Riverside Bayview, 474 U.S. at 131). ``It is quite a stretch to claim,
however, that this mention of hydrographic features `echoe[s]' the
dictionary's reference to ` ``geographical features such as oceans,
rivers, [and] lakes.'' ' Rapanos, 547 U.S. at 771 (citation omitted).
``In fact, the Riverside Bayview opinion does not cite the dictionary
definition on which the plurality relies, and the phrase `hydrographic
features' could just as well refer to intermittent streams carrying
substantial flow to navigable waters.'' Id. at 771 (citing Webster's
Second 1221 (defining ``hydrography'' as ``[t]he description and study
of seas, lakes, rivers, and other waters; specif[ically] . . . [t]he
measurement of flow and investigation of the behavior of streams,
esp[ecially] with reference to the control or utilization of their
waters'')).
    With respect to wetlands, the agencies have also concluded there is
no sound basis in the text of the Clean Water Act or in other Supreme
Court precedent for requiring that wetlands can be jurisdictional only
if they satisfy the continuous surface connection requirement of the
relatively permanent standard. The Rapanos plurality's rationale for
adopting such a test rested largely on a misreading of Riverside
Bayview. The plurality's brief discussion did not otherwise attempt to
ground its relatively permanent standard in the text, history, or
purpose of the Clean Water Act. In concluding that only wetlands with a
continuous surface connection to other covered waters are protected by
the Clean Water Act, the Rapanos plurality relied primarily on two
related propositions that it viewed as implicit in Riverside Bayview.
First, the plurality suggested that in Riverside Bayview the Clean
Water Act term ``waters'' cannot easily be construed to cover wetlands,
and that discharges into wetlands therefore can be regulated only when
particular wetlands ``adjoined'' waters of the United States and were
thus deemed ``part of'' the waters to which they are adjacent. See 547
U.S. at 740. Second, the plurality concluded that this requirement will
be satisfied only when ``the wetland has a continuous surface
connection with [the adjacent] water.'' Id. at 742. Those propositions
are unsound and rest on a misreading of Riverside Bayview.
    The Rapanos plurality quoted the Riverside Bayview Court's
statement that, ``[o]n a purely linguistic level, it may appear
unreasonable to classify `lands,' wet or otherwise, as `waters.' '' 547
U.S. at 740 (quoting Riverside Bayview, 474 U.S. at 132). In the next
sentence of its opinion, however, the Riverside Bayview Court
continues, and the Rapanos plurality omits, that ``[s]uch a simplistic
response . . . does justice neither to the problem faced by the Corps
in defining the scope of its authority under Sec.  404(a) nor to the
realities of the problem of water pollution that the Clean Water Act
was intended to combat.'' 474 U.S. at 132. The Riverside Bayview Court
concluded that ``adjacent wetlands may be defined as waters under the
Act.'' Id. at 134. And, as explained above, the Clean Water Act's text,
history, and purpose likewise confirm that adjacent wetlands are
themselves ``waters'' covered by the Act.
    The Rapanos plurality read Riverside Bayview as resting on the
``inherent ambiguity in drawing the boundaries of any `waters.''' 547
U.S. at 740. The plurality also described SWANCC as having read
Riverside Bayview to be ``refer[ring] to the close connection between
waters and the wetlands that they gradually blend into.'' Rapanos, 547
U.S. at 741. The plurality concluded that ``only those wetlands with a
continuous surface connection to bodies that are `waters of the United
States' in their own right'' can be protected by the Clean Water Act,
because only in that circumstance is it ``difficult to determine where
the `water' ends and the `wetland' begins.'' Id. at 742. However, the
Rapanos plurality misconceived the nature of the line-drawing problem
in Riverside Bayview. The Riverside Bayview Court identified
``shallows, marshes, mudflats, swamps, [and] bogs'' as examples of
``areas that are not wholly aquatic but nevertheless fall far short of
being dry land,'' and it

observed that ``[w]here on this continuum to find the limit of `waters'
is far from obvious.'' 474 U.S. at 132. The line-drawing problem in
Riverside Bayview did not involve identifying the boundary between a
jurisdictional stream and an adjacent wetland. Rather, the line-drawing
problem involved the criteria that should be used to determine whether
particular types of hydrogeographic features should be regarded as
``waters'' under the Clean Water Act. That line-drawing problem--in
essence, determining how wet is wet enough--can arise even when a
particular swamp or marsh is separated by a barrier from a nearby lake
or stream. After discussing at some length the regulatory definition of
``wetlands'' and its application to the property at issue in that case,
see id. at 129-131, the Riverside Bayview Court upheld as reasonable
``the Corps' approach of defining adjacent wetlands as `waters' within
the meaning of'' the Clean Water Act. Id. at 132.
    As further support for its relatively permanent standard, the
Rapanos plurality invoked SWANCC's holding that certain isolated ponds
were not covered by the Clean Water Act. The SWANCC Court had described
Riverside Bayview as resting on ``the significant nexus between the
wetlands and'' the waters to which they are adjacent. 531 U.S. at 167.
The Rapanos plurality in turn described SWANCC as ``reject[ing] the
notion that the ecological considerations upon which the Corps relied
in Riverside Bayview . . . provided an independent basis for including
entities like `wetlands' . . . within the phrase `the waters of the
United States.' '' 547 U.S. at 741 (citation omitted). In the
plurality's view, ``SWANCC found such ecological considerations
irrelevant to the question whether physically isolated waters come
within the Corps' jurisdiction,'' because the coverage inquiry for the
``[i]solated ponds'' at issue in that case ``presented no boundary-
drawing problem that would have justified the invocation of ecological
factors.'' Id. at 741-742. Contrary to the Rapanos plurality's
suggestion, the Court in SWANCC did not hold that the particular
``ecological considerations upon which the Corps relied in Riverside
Bayview,'' 547 U.S. at 741--i.e., the potential importance of wetlands
to the quality of adjacent waters--were irrelevant to Clean Water Act
jurisdiction. Rather, the Court held that a different ecological
concern, namely the potential use of the isolated ponds as habitat for
migratory birds, could not justify treating those ponds as ``waters of
the United States.'' See 531 U.S. at 164-165, 171-172. That ecological
concern was not cognizable because it was unrelated to ``what Congress
had in mind as its authority for enacting the CWA: its traditional
jurisdiction over waters that were or had been navigable in fact or
which could reasonably be so made.'' Id. at 172 (citation omitted).
    Aside from its mistaken reliance on Riverside Bayview and SWANCC,
the Rapanos plurality did not attempt to ground the relatively
permanent standard in the Clean Water Act's text or history. See 547
U.S. at 739-742. And limiting Clean Water Act coverage to wetlands with
a continuous surface connection would affirmatively undermine the Act's
purpose by creating an illogical jurisdictional gap. It would
categorically exclude wetlands separated from covered waters by a dike
or similar barrier, even if they are closely connected by subsurface
flow or periodic floods, regardless of such wetlands' ecological
importance to covered waters nearby and downstream. The agencies have
concluded that overwhelming scientific evidence shows that such
wetlands may significantly affect paragraph (a)(1) waters. See Science
Report 4-20 to 4-38; Technical Support Document section III.B.
    Additionally, the relatively permanent standard was not briefed in
Rapanos. See 547 U.S. at 800 (Stevens, J., dissenting). And the
plurality's terse discussion of the issue did not elaborate on either
aspect of that standard in any detail. The plurality stated that
``relatively permanent'' does not necessarily exclude waters ``that
might dry up in extraordinary circumstances, such as drought'' or
``seasonal rivers, which contain continuous flow during some months of
the year but no flow during dry months.'' 547 U.S. at 732 n.5 (emphasis
in original). The Rapanos plurality distinguished a ``continuous
surface connection'' from ``an intermittent, physically remote
hydrologic connection,'' but gave little further guidance on the
application of its test. Id. at 742 (plurality opinion). As long as the
relatively permanent standard is understood as a useful but not
exclusive standard for Clean Water Act coverage, it has not created
arbitrary and harmful results.
    If the relatively permanent standard were the sole standard, a
small surface connection would suffice, but the presence of a levee to
protect a river and its adjacent wetlands could strip the wetlands of
Clean Water Act coverage since, under the relatively permanent
standard, a human-made barrier such as a levee means that there is not
a continuous surface connection between the river and the wetlands.
This result would be irrational and contrary to the objectives of the
statute. The Mississippi River, for example, features an extensive
levee system built to prevent flooding. The Upper Mississippi Valley
alone includes approximately 17,000 kilometers (more than 10,000 miles)
of levees. Technical Support Document section III.B.ii.2. Those levees
would preclude Clean Water Act coverage under the relatively permanent
standard even though adjacent wetlands are often a necessary part of
the flood-control project--detaining floodwaters to protect surrounding
and downstream communities--and even though the wetlands maintain a
hydrologic connection to the river system. Cf. R. Daniel Smith &
Charles V. Klimas, Eng'r Rsch. & Dev. Ctr., A Regional Guidebook for
Applying the Hydrogeomorphic Approach to Assessing Wetland Functions of
Selected Regional Wetland Subclasses, Yazoo Basin, Lower Mississippi
River Alluvial Valley 47, 48-49 (April 2002).
    More broadly, the relatively permanent standard's continuous
surface connection requirement could make loss of Clean Water Act
jurisdiction a consequence of building a road, levee, or other
barrier--even if the construction had little or no effect on the
interdependent relationship between a wetland and a neighboring water.
That could create perverse incentives to build or modify such barriers
in a manner aimed either at destroying or preserving Federal
jurisdiction.
    Further, as discussed above, Congress declined to narrow the scope
of ``waters of the United States'' when it amended the Clean Water Act
in 1977. The relatively permanent standard amends the Clean Water Act
to limit its scope in ways that Congress has considered doing but has
repeatedly declined to do, including through legislation introduced
after the Rapanos decision and after promulgation of the 2020 NWPR.\61\
As Justice Kennedy stated:

``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.'' 547 U.S. at 770.
---------------------------------------------------------------------------

    \61\ See, e.g., Navigable Waters Protection Act, S. 2567, 117th
Cong. (2021) (proposing to codify the 2020 NWPR as Federal
legislation); Define WOTUS Act, S. 2356, 116th Cong. (2019)
(proposing to revise the Clean Water Act to define ``navigable
waters'' to include the territorial seas, interstate waters used in
the transport of interstate or foreign commerce, and waters meeting
the Rapanos plurality's standard); S.J. Res. 22, 114th Cong. (2015)
(proposing to nullify the 2015 Clean Water Rule); Defense of
Environment and Property Act, H.R. 3377, 113th Cong. (2013)
(proposing to revise the Clean Water Act to limit ``waters of the
United States'' to navigable-in-fact waters and ``permanent or
continuously flowing bodies of water that form geographical features
commonly known as streams, oceans, rivers, and lakes that are
connected to waters that are navigable-in-fact''); Amendment 2177,
S. 3240, 112th Cong. (2012) (proposing to amend an appropriations
bill to limit the Clean Water Act's definition of ``waters of the
United States'' to navigable-in-fact waters and ``permanent,
standing or continuously flowing bodies of water that form
geographical features commonly known as streams, oceans, rivers, and
lakes that are connected to waters that are navigable-in-fact'').
---------------------------------------------------------------------------

    Finally, the agencies have consistently construed Rapanos to mean
that a water is jurisdictional under the Clean Water Act if it meets
either the relatively permanent standard or the significant nexus
standard. The 2020 NWPR, however, interpreted the statute to primarily
find waters jurisdictional only if they met the relatively permanent
standard, as that standard was specifically interpreted in the 2020
NWPR. The 2020 NWPR argued that it reflected both the plurality and
Kennedy opinions, which it characterized as having ``sufficient
commonalities . . . to help instruct the agencies on where to draw the
line between Federal and State waters.'' 85 FR 22250, 22268 (April 21,
2020). The opinions have important differences, however. Justice
Kennedy looked to the existence of a significant nexus between waters
at issue and traditional navigable waters, whereas the plurality held
that ``waters of the United States'' is limited to ``relatively
permanent'' waters connected to traditional navigable waters, and
wetlands with a ``continuous surface connection'' with those waters.
Rapanos, 547 U.S. at 742. Justice Kennedy rejected these two
limitations in the plurality as ``without support in the language and
purposes of the Act or in our cases interpreting it.'' Id. at 768; see
also id. at 776 (``In sum the plurality's opinion is inconsistent with
the Act's text, structure, and purpose.''). Yet the plurality's
limitation of jurisdiction to ``relatively permanent'' waters and those
with a ``continuous surface connection'' to those waters pervades the
2020 NWPR. See 85 FR 22338-39; see also 2020 NWPR regulatory text at 33
CFR 328.3(a), (c)(1), (c)(6), (c)(12). The 2020 NWPR disregards the
significant nexus standard, see generally 85 FR 22270, 22338-39 (April
21, 2020); 33 CFR 328.3, and, in doing so, restricted the scope of the
statute using limitations Justice Kennedy viewed as anathema to the
purpose and text of the Clean Water Act. For the reasons articulated
throughout sections IV.A and IV.B of this preamble, the agencies reject
the 2020 NWPR's interpretation of ``waters of the United States'' as
inconsistent with the objective of the Clean Water Act, the science,
and the case law.
    While the relatively permanent standard is administratively useful
and includes waters that have important effects on the water quality of
paragraph (a)(1) waters, the standard excludes waters that properly
fall within the Clean Water Act's protections. As a result, this rule's
incorporation of jurisdictional limitations based upon the relatively
permanent standard and the significant nexus standard reflects the text
of the statute as a whole. Thus, with this rule, the agencies properly
fulfill their congressionally delegated responsibility to construe
``waters of the United States'' in a manner that advances the objective
of the Act.
iii. Fact-Based Standards for Determining Clean Water Act Jurisdiction
Are Appropriate
    The agencies have the discretion to consider defining waters as
jurisdictional on a categorical basis where scientifically and legally
justified (for example in this rule, paragraph (a)(1) waters and their
adjacent wetlands) or a case-specific, fact-based approach (for
example, in this rule, tributaries and their adjacent wetlands that
meet the significant nexus standard or relatively permanent standard).
While the latter does not necessarily provide the same certainty as
defining waters as jurisdictional by category, case-specific
determinations of the scope of Clean Water Act jurisdiction are not
unusual--in fact, they are the norm. In the Supreme Court's most recent
decision addressing a question about the jurisdictional scope of the
Clean Water Act, although not the scope of ``waters of the United
States,'' the Court established a standard for determining jurisdiction
that does not establish bright lines marking the bounds of Federal
jurisdiction. Instead, like the significant nexus standard, the
standard in Maui requires an inquiry focused on the specific facts at
issue and is guided by the purposes Congress sought to achieve under
the Clean Water Act. In Maui, the Supreme Court considered whether
discharges to groundwater that reach navigable waters are
jurisdictional under the Clean Water Act and thus subject to the Act's
section 402 permitting program. The Court held that ``the statute
requires a permit when there is a direct discharge from a point source
into navigable waters or when there is the functional equivalent of a
direct discharge.'' Maui, 140 S. Ct. at 1476. The Court explained that
``[w]e think this phrase best captures, in broad terms, those
circumstances in which Congress intended to require a federal permit.''
Id. The Court further explained that, in applying its broadly worded
standard, ``[t]he object in a given scenario will be to advance, in a
manner consistent with the statute's language, the statutory purposes
that Congress sought to achieve.'' Id. The Court recognized that the
difficulty with its approach was that ``it does not, on its own,
clearly explain how to deal with middle instances,'' but reasoned that
``there are too many potentially relevant factors applicable to
factually different cases for this Court now to use more specific
language.'' Id. The Court enumerated a series of factors relevant to
determining whether a discharge is the ``functional equivalent'' of
direct discharge, including the time between when the discharge occurs
and when the pollutants reach the navigable water, the distance the
pollutants travel to the navigable water, the nature of the material
through which the pollutant travels, the extent to which the pollutant
is diluted or chemically changed as it travels, the amount of pollutant
entering the navigable waters relative to the amount of the pollutant
that leaves the point source, the manner by or area in which the
pollutant enters the navigable waters, and the degree to which the
pollution (at that point) has maintained its specific identity. Id. at
1476-77.
    The Supreme Court's ``functional equivalent'' standard has several
key characteristics in common with the significant nexus standard and
the agencies' approach in this rule. Both standards require an analysis
focused on the specific facts at issue in a particular instance. Under
the ``functional equivalent'' standard, factors that may be relevant,
depending on the circumstances of a particular case, include transit
time, distance traveled, the geologic substrate through which the
discharges travels, the location and nature of the receiving water, and
other factors. Similarly, the significant nexus standard requires
consideration of scientific principles of upstream functions and
effects on the integrity of paragraph (a)(1) waters and facts related
to the specific waters at issue. Indeed, this rule includes a list of
factors that would be considered when assessing whether waters
significantly affect paragraph (a)(1) waters that is similar in nature
to the factors identified by the Court that may be relevant to making a
``functional equivalent'' assessment. See section IV.C.9 of this
preamble. The relatively permanent standard also

requires inquiry into specific facts about particular tributaries,
wetlands, and open waters, although the inquiry generally requires less
information-gathering and assessment than the significant nexus
standard. The Court in Maui also explicitly rejected EPA's suggested
approach, which established a bright line that categorically excluded
all discharges to groundwater regardless of whether they reached
navigable waters and instead adopted the ``functional equivalent''
analysis. 140 S. Ct. at 1474-75. The Maui Court's analysis underscores
the agencies' concerns about the 2020 NWPR, which categorically
excluded all ephemeral tributaries and wetlands that did not meet its
very narrow definition in spite of their impact on the chemical,
physical, and biological integrity of paragraph (a)(1) waters. In this
rule, the agencies are rejecting that approach and resuming the use of
the significant nexus standard to determine which waters have a
sufficient impact on traditional navigable waters, the territorial
seas, or interstate waters.
    Finally, both the functional equivalent standard and the
significant nexus standard should be applied while keeping in mind the
purposes of the Clean Water Act. As the Court explained in Maui,
``[t]he underlying statutory objectives also provide guidance.
Decisions should not create serious risks either of undermining state
regulation of groundwater or of creating loopholes that undermine the
statute's basic federal regulatory objectives.'' Id. at 1477. Likewise,
Justice Kennedy explained that, when assessing the existence of a
``significant nexus'' between wetlands and navigable waters, ``[t]he
required nexus must be assessed in terms of the statute's goals and
purposes.'' Rapanos, 547 U.S. at 779.
    The agencies recognize that in both Rapanos and Maui, the Supreme
Court was clear that the agencies could promulgate regulations that
further refine the case-specific jurisdictional tests. With this rule,
the agencies have established limits that appropriately draw the
boundary of ``waters of the United States'' by ensuring that, where
upstream waters significantly affect the integrity of waters and the
Federal interest is indisputable--the traditional navigable waters, the
territorial seas, and interstate waters--Clean Water Act programs apply
to ensure that the downstream waters are adequately protected (by
protecting those upstream waters). This rule continues the use of case-
specific jurisdictional tests but also provides needed clarity by
establishing regulations that include definitions of key terms and
specific exclusions. Moreover, the agencies have extensive experience
making jurisdictional determinations using the relatively permanent
standard and the significant nexus standard. Field staff have gained
extensive familiarity and practical experience with the national and
regionally specific field methods, literature, datasets, models, and
tools that are required to make such determinations, resulting in
increased efficiencies over time. See section IV.C.10 of this preamble.
In addition, this rule increases clarity and implementability by
streamlining and restructuring the 1986 regulations, and this preamble
provides implementation guidance informed by sound science,
implementation tools (including modern assessment tools), and other
resources.
b. This Rule Reflects Full and Appropriate Consideration and Balancing
of the Water Quality Objective in Section 101(a) and the Policies
Relating to Responsibilities and Rights of Tribes and States Under
Section 101(b) of the Clean Water Act
    This rule reflects consideration of the statute as a whole,
including the objective of the Clean Water Act and the policies of the
Act with respect to the role of Tribes and States. As discussed in
section IV.A.2.a of this preamble, the agencies must consider the
objective of the Clean Water Act in interpreting the scope of the
statutory term ``waters of the United States.'' In this rule, the
agencies also consider the entire statute, including section 101(b) of
the Clean Water Act, which provides that it is congressional policy to
preserve the primary responsibilities and rights of States ``to
prevent, reduce, and eliminate pollution, to plan the development and
use . . . of land and water resources, and to consult with the
Administrator in the exercise of [the Administrator's] authority''
under the Clean Water Act. 33 U.S.C. 1251(b). Determining where to draw
the boundaries of Federal jurisdiction to ensure that the agencies
advance Congress's objective while preserving and protecting the
responsibilities and rights of the States is a matter of judgment
assigned by Congress to the agencies.
    The agencies find that this rule both advances the objective of the
Clean Water Act in section 101(a) and respects the role of Tribes and
States in section 101(b).\62\ The rule appropriately draws the boundary
of waters subject to Federal protection by limiting the scope to the
protection of upstream waters that significantly affect the integrity
of waters where the Federal interest is indisputable--the traditional
navigable waters, the territorial seas, and interstate waters. Waters
that do not implicate the Federal interest in these paragraph (a)(1)
waters are not included within the scope of Federal jurisdiction. The
scope and boundaries of the definition therefore reflect the agencies'
considered judgment of both the Clean Water Act's objective in section
101(a) and the congressional policy relating to States' rights and
responsibilities under section 101(b).
---------------------------------------------------------------------------

    \62\ While Clean Water Act section 101(b) does not specifically
identify Tribes, the policy of preserving States' sovereign
authority over land and water use is equally relevant to ensuring
the primary authority of Tribes to address pollution and plan the
development and use of Tribal land and water resources.
---------------------------------------------------------------------------

    The agencies have carefully considered sections 101(a) and 101(b)
as well as the agencies' analysis and application of these provisions
in promulgating the 2020 NWPR. In several key respects, the agencies'
consideration and weighing of these provisions in this rulemaking
differs from the agencies' approach in the 2020 NWPR. The agencies
explained in the preamble to the proposed rule why the agencies'
revised approach represents a fuller and more appropriate consideration
of these provisions than reflected in the 2020 NWPR, and the agencies
reaffirm those positions. 86 FR 69399 (December 7, 2021). As discussed
below, based on the text of section 101(b), the structure of section
101 and the Clean Water Act as a whole, Supreme Court precedent, and
the history of Federal water pollution laws enacted by Congress up
through the 1972 amendments, the construction of the Act in this rule
fully and appropriately considers sections 101(a) and 101(b).
    The policy in section 101(b) is both important and relevant to the
agencies' defining an appropriate scope of ``waters of the United
States.'' Consistent with the text of the statute and as emphasized by
the Supreme Court, Federal jurisdiction under the Clean Water Act has
limits. As explained above, Clean Water Act jurisdiction encompasses
(and is limited to) those waters that significantly affect the
indisputable Federal interest in the protection of the paragraph (a)(1)
waters--i.e., traditional navigable waters, the territorial seas, and
interstate waters. And consistent with the section 101(b) policy, where
protection (or degradation) of waters does not implicate this Federal
interest, such waters fall exclusively within Tribal or

State regulatory authority should they choose to exercise it. However,
there is no indication in any text of the statute that Congress
established section 101(b) as the lynchpin of defining the scope of
``waters of the United States.'' Rather, the Clean Water Act's
objective--restoring and maintaining the chemical, physical, and
biological integrity of the nation's waters--is set forth in the first
words of the first section of the statute. And the statute is designed
to address that objective through a ``comprehensive'' Federal program
of pollution control. Indeed, the text of section 101(b) is actually a
recognition of States' authority to ``prevent, reduce, and eliminate
pollution'' and provide support for the Administrator's exercise of his
or her authority to advance the objective of the Clean Water Act.
    The text of section 101(b) also expressly recognizes States' role
in administering the Federal permitting programs under section 402 of
the Clean Water Act:

    It is the policy of Congress that the States manage the
construction grant program under this chapter and implement the
permit programs under sections 1342 [402] and 1344 [404] of this
title. It is further the policy of the Congress to support and aid
research relating to the prevention, reduction, and elimination of
pollution, and to provide Federal technical services and financial
aid to State and interstate agencies and municipalities in
connection with the prevention, reduction, and elimination of
pollution.

    Thus, the text of section 101(b) as a whole does not reflect a
general policy of deference to State regulation to the exclusion of
Federal regulation, which would be inconsistent with Congress's
enactment of the Clean Water Act because of the failures of a statutory
scheme that relied primarily on State enforcement of State water
quality standards. S. Rep. No. 92-414, 92d Cong., 1st Sess. 7 (1971)
(observing that prior statutes had been ``inadequate in every vital
aspect''). Instead, section 101(b) sets forth a policy focused on
preserving the responsibilities and rights of States to work to achieve
the objective of the Act. Those rights and responsibilities are to
prevent, reduce, and eliminate pollution generally, including, but not
limited to, through their authority over any source of pollution
subject to State law, consulting with the Administrator in the exercise
of his or her Clean Water Act authority, and implementing the Act's
regulatory permitting programs, in partnership and with technical and
financial support from the Federal Government.
    The agencies' interpretation and consideration of section 101(b) in
this rule is consistent with Supreme Court precedent. The Supreme Court
has described, on numerous occasions, section 101(b) as creating a
partnership between the Federal and State governments in which the
States administer programs under federally mandated standards and are
allowed to set even more stringent standards. See, e.g., Arkansas v.
Oklahoma, 503 U.S. 91, 101 (1992) (stating that the Act ``anticipates a
partnership between the States and the Federal government'' to meet the
``shared objective'' in section 101(a), with the Federal Government
setting pollutant discharge limitations and States implementing water
quality standards for their respective waterbodies); Int'l Paper Co. v.
Ouellette, 479 U.S. 481, 489-90 (1987) (describing section 101(b) as
allowing the Federal Government to delegate administration of point
source pollution permits to States and allowing States to establish
more stringent discharge limitations than Federal requirements); Train
v. Colo. Pub. Interest Grp., 426 U.S. 1, 16 & n.13 (1976) (describing
section 101(b) as providing States authority to develop permit programs
and establish standards more stringent than those under the Clean Water
Act); see also City of Milwaukee v. Illinois, 451 U.S. 304, 341 (1981)
(Blackmun, J., dissenting) (describing section 101(b) as creating
``shared authority between the Federal Government and the Individual
States'' that allows for the States to set more stringent standards
than necessary by Federal law). While this rule does not directly
establish or alter a Clean Water Act program, these decisions informed
the agencies' deliberations because the definition of ``waters of the
United States'' affects the scope of Clean Water Act programs.
    The agencies have also carefully considered the policy in section
101(b) as it relates to the Clean Water Act's objective in section
101(a). The Clean Water Act's structure makes clear that section 101(a)
sets forth the foundational purpose of the statute that must be
achieved. First, section 101(a) is the opening section of the statute
and is labelled the ``objective'' of the Clean Water Act. The agencies
interpret its placement and its simple, declarative, and overarching
statement as a powerful expression by Congress that merits substantial
weight in defining the scope of jurisdiction for all of the Clean Water
Act's regulatory programs. In contrast, section 101(b) is one of four
congressional policies contained in section 101; the other three relate
to seeking to ensure foreign countries take action to prevent, reduce,
and eliminate pollution; reducing paperwork, duplication, and
government delays; and State authority to allocate quantities of water
within their jurisdictions. See 33 U.S.C. 1251(c), (f), (g). Just as
none of those policies plays a central role in defining the scope of
the Clean Water Act, neither should section 101(b) be given such
prominence as to undermine Congress's stated objective. The prominently
placed and single expression of the Clean Water Act's overarching
objective in section 101(a) merits greater weight in the agencies'
decision-making than any of the four congressional policies expressed
in section 101 which, while important, appear subordinate to the
objective--particularly given the statutory text and structure. To the
extent there is ambiguity, the agencies have been delegated the
authority to define ``waters of the United States'' and again conclude
based on the statutory text and structure, and confirmed by the
legislative history, that the overarching objective of the Act merits
greater weight. The agencies have also thoroughly considered the other
policies in section 101 of the Act, especially section 101(b) as
discussed in this section of the preamble.
    The remainder of the Clean Water Act's text also demonstrates how
important this objective was to Congress. In the Clean Water Act
itself, Congress refers to the objective of the Act approximately a
dozen times, including in sections 104, 105, 117, 120, 217, 301, 303,
304, 305, 308, 319, 402, 516, 518, and 603. The repeated reference to
the objective highlights the importance of the Clean Water Act's
objective to the statute as a whole, supporting the agencies' giving
substantial weight to this provision. Section 101(b), in contrast, is
not referred to elsewhere in the Clean Water Act.
    Congress itself defined the contours of how it expected the
agencies to both achieve its objective in section 101(a) and implement
its policy in section 101(b) through the rest of the provisions of the
Clean Water Act. Notably, a narrow definition of ``waters of the United
States'' would not uniformly boost State authority as that definition
is foundational to the scope of all of the Clean Water Act's programs,
including those in which the States are assigned authority. Indeed, in
implementing Clean Water Act regulatory requirements, States can have
more powerful and holistic tools than they would have in implementing
State-only laws and regulations. For example,

section 401 requires State certification for federally licensed
projects within a State's borders. A narrow definition of ``waters of
the United States'' would thus actually limit States' ability to
protect waters within their borders. Similarly, a narrow definition
would limit the ability of a State to provide input during the
permitting process for out-of-state section 402 and 404 permits that
may affect its waters. See 33 U.S.C. 1341, 1342(b), 1344(h)(1)(E).
    The agencies' careful balancing of section 101(a) and 101(b) in
this rule is also informed by and consistent with the Court's decision
in SWANCC, wherein the Court stated: ``Congress chose to `recognize,
preserve, and protect the primary responsibilities and rights of States
. . . to plan the development and use . . . of land and water
resources. . . .' We thus read the statute as written to avoid the
significant constitutional and federalism questions.'' 531 U.S. at 174
(citing 33 U.S.C. 1251(b)). Justice Kennedy further explained in
Rapanos: ``In SWANCC, by interpreting the Act to require a significant
nexus with navigable waters, the Court avoided applications--those
involving waters without a significant nexus--that appeared likely, as
a category, to raise constitutional difficulties and federalism
concerns.'' 547 U.S. at 776. Likewise here, this rule--by limiting
jurisdiction only to those waters that significantly affect the
integrity of waters where the Federal interest is indisputable
(traditional navigable waters, the territorial seas, and interstate
waters)--avoids constitutional and federalism concerns.
    Under the Commerce Clause, Congress can regulate: (1) the channels
of interstate commerce; (2) persons or things in interstate commerce;
and (3) activities that substantially affect interstate commerce.
United States v. Lopez, 514 U.S. 549, 558-59 (1995). Regulation of
``waters of the United States'' as interpreted by this rule is a valid
exercise of Congress's power under at least the first Lopez category.
It is a well-settled proposition that Congress's power to regulate
channels of interstate commerce also includes the power to adopt
``appropriate and needful control of activities and agencies which,
though intrastate, affect that commerce.'' Rapanos, 547 U.S. at 782-83
(citing Oklahoma ex rel. Phillips v. Guy F. Atkinson Co., 313 U.S. 508,
525-26 (1941)). Traditional navigable waters are squarely within
Congress's power to regulate under its authority over the channels of
interstate commerce. And ``[i]t has long been settled that Congress has
extensive authority over this Nation's waters under the Commerce
Clause'' as channels of interstate commerce. See Kaiser Aetna v. United
States, 444 U.S. 164, 173 (1979). Indeed, Congress has enacted
``numerous laws touching interstate waters.'' City of Milwaukee, 406
U.S. at 101. Congress has broad power to keep the channels of commerce
free from injurious uses. See, e.g., Pierce Cnty. v. Guillen, 537 U.S.
129, 146-47 (2003); Lopez, 514 U.S. at 558; Perez v. United States, 402
U.S. 146, 150 (1971); Caminetti v. United States, 242 U.S. 470, 491
(1917); The Lottery Case (Champion v. Ames), 188 U.S. 321, 346-47
(1903). Thus, courts have recognized that the power over traditional
navigable waters as channels of commerce includes ``the power to
regulate waters to limit pollution, prevent obstructions to navigation,
reduce flooding, and control watershed development.'' United States v.
Hubenka, 438 F.3d 1026, 1032 (10th Cir. 2006) (citations omitted). As
noted earlier, Congress directed that the Clean Water Act ``be given
the broadest possible constitutional interpretation,'' S. Conf. Rep.
No. 92-1236, 92d Cong., 2d Sess. 144 (1972), and the ``Commerce Clause
[is] broad enough to permit congressional regulation of activities
causing air or water pollution, or other environmental hazards that may
have effects in more than one State.'' Hodel v. Va. Surface Mining &
Reclamation Ass'n, 452 U.S. 264, 282 (1981). The Supreme Court has
stated that the term ``navigable'' must be given some meaning in
defining ``waters of the United States.'' SWANCC, 531 U.S. at 172;
Rapanos, 547 U.S. at 779 (Kennedy, J., concurring in the judgment). The
agencies' construction of the Clean Water Act does that by defining
``waters of the United States'' to include traditional navigable
waters, the territorial seas, and interstate waters, and those waters
that significantly affect those waters. But while Congress was
utilizing only one prong of its Commerce Clause authority, that prong
is nevertheless broad. Indeed, ``there is no reason to believe Congress
has less power over navigable waters than over other interstate
channels,'' such that Congress cannot regulate non-navigable waters in
order to protect water quality in traditional navigable waters. United
States v. Deaton, 332 F.3d 698, 707 (4th Cir. 2003). This rule and the
significant nexus standard are squarely within the prong of Commerce
Clause authority that Congress utilized in enacting the Clean Water Act
and within the authority Congress delegated to the agencies under the
Act. Both the rule and the standard are based on protecting traditional
navigable waters, the territorial seas, and interstate waters from the
effects of upstream pollution.
    Finally, in considering sections 101(a) and 101(b) for purposes of
interpreting the scope of ``waters of the United States,'' the agencies
conclude that it is important to consider the statutory history that
gave rise to this structure. Indeed, the agencies recognize that in
passing the Federal Water Pollution Control Act Amendments of 1972,
Congress was not acting on a blank slate--it was amending existing law
that had primarily provided for States to establish water quality
standards for a subset of waters. Water Quality Act of 1965, Public Law
89-234, 79 Stat. 903 (1965). Congress found the previous statute's
focus on States' establishment and administration of water quality
standards insufficient for the task of upgrading and protecting the
quality of America's waters because States were lagging in establishing
such standards and there was ``an almost total lack of enforcement.''
S. Rep. 92-414 (1971) at 5. The Clean Water Act was enacted to address
these shortcomings after ``two of the important rivers [in the Sixth]
circuit, the Rouge River in Dearborn, Michigan, and the Cuyahoga River
in Cleveland, Ohio, reached a point of pollution by flammable materials
in the last ten years that they repeatedly caught fire.'' United
States. v. Ashland Oil & Transp. Co., 504 F.2d 1317, 1326 (6th Cir.
1974). With the 1972 amendments, Congress adopted an entirely new
approach to water pollution control--a prohibition of discharges of
pollutants unless authorized by the Clean Water Act and a new,
comprehensive, Federal regulatory scheme grounded in technology-based
effluent standards applied uniformly across industries of the same
type. ``The Committee recommends the change to effluent limits as the
best available mechanism to control water pollution. With effluent
limits, the Administrator can require the best control technology.'' S.
Rep. 92-414 at 8. Congress also viewed the prohibition on discharges of
pollutants unless authorized under the Act as ``establish[ing] a direct
link between the Federal government and each industrial source of
discharge into the navigable waters.'' Id. Thus, Congress viewed the
Clean Water Act as a change from previous laws that centered on States
and State water quality standards to a system based on a prohibition of
discharges of pollutants to waters unless permitted in accordance with
a Federal regulatory scheme and technology standards established by
EPA. Tribes

and States play a vital role in the implementation and enforcement of
the Clean Water Act, and this rule does not change that framework.
Instead, this rule reinforces that framework by establishing
limitations that reflect careful consideration of how best to identify
those waters for which Federal regulation is necessary to ensure the
protection of the waters at the core of Congress's authority and
interest and those for which it is not.
    In the context of the scope of ``waters of the United States,'' the
Court stated that Congress ``intended to repudiate limits that had been
placed on federal regulation by earlier water pollution control
statutes and to exercise its powers under the Commerce Clause to
regulate at least some waters that would not be deemed `navigable'
under the classical understanding of that term.'' Riverside Bayview,
474 U.S. at 133. More recently, the Supreme Court in Maui also noted
that: ``Prior to the Act, Federal and State Governments regulated water
pollution in large part by setting water quality standards. The Act
restructures federal regulation by insisting that a person wishing to
discharge any pollution into navigable waters first obtain EPA's
permission to do so.'' 140 S. Ct. at 1468 (citations omitted).
    With respect to States' responsibilities and rights under section
101(b), Justice Kennedy in Rapanos cited State amici briefs that
``note[d], among other things, that the Act protects downstream States
from out-of-state pollution that they cannot themselves regulate.'' 547
U.S. at 777. Indeed, the Supreme Court has recognized that this is an
important aspect of the Clean Water Act's passage. City of Milwaukee
involved alleged discharges of inadequately treated sewage from
Milwaukee, Wisconsin, sewer systems directly into Lake Michigan, which
also borders Illinois. The City of Milwaukee Court noted that prior to
passage of the Clean Water Act, these discharges would have had to be
resolved through litigation, in which the courts must apply ``often
vague and indeterminate nuisance concepts and maxims of equity
jurisprudence.'' 451 U.S. at 317. The Clean Water Act, however,
replaced this unpredictable and inefficient approach with ``a
comprehensive regulatory program supervised by an expert administrative
agency,'' id., including a ``uniform system of interstate water
pollution regulation,'' Arkansas v. Oklahoma, 503 U.S. 91, 110 (1992).
    An overly narrow definition of jurisdictional waters would threaten
a return to pre-1972 regime, would exclude from Federal protection
waters that significantly affect paragraph (a)(1) waters, and would
risk removing from the statutory scheme instances of interstate
pollution the 1972 amendments were designed in part to address.
Nationwide pollution controls are critical to protecting water quality
in downstream States because downstream States have limited ability to
control water pollution sources in upstream States. See Int'l Paper Co.
v. Ouellette, 479 U.S. at 490-91. Several commenters stated that, under
the 2020 NWPR, certain States were subject to harm from increased
pollution flowing through interstate waters from upstream States. In
addition, commenters noted that the water quality in States bordering
the Great Lakes depended on adequate protection in other Great Lakes
States, some of which removed clean water regulations following
promulgation of the 2020 NWPR. The consequences of water pollution
discharged in one State and flowing to another are also economic in
nature. Such pollution also destroys or diminishes the value of water
to ``public water supplies, propagation of fish and wildlife,
recreational purposes, and agricultural, industrial, and other
purposes'' protected by the Clean Water Act. 33 U.S.C. 1313(c)(2)(A).
    Moreover, an overly narrow definition of ``waters of the United
States'' would substantially impinge upon States' responsibilities and
rights under section 401 of the Clean Water Act. It is only through
that provision of the Act that States have the authority to grant,
deny, or waive certification of proposed Federal licenses or permits
that may discharge into waters of the United States.
    By promulgating a rule interpreting the Clean Water Act to cover
waters that meet the relatively permanent standard or the significant
nexus standard, the agencies have appropriately construed the Act to
protect those waters necessary to protect the integrity of traditional
navigable waters, the territorial seas, and interstate waters, while
leaving regulatory authority over all the waters that do not have the
requisite connection to paragraph (a)(1) waters exclusively to the
Tribes and States. This construction respects the statutory history
that gave rise to the Clean Water Act and gives effect to the
comprehensive nature of the Act, its objective, and the many programs
and policies affected by the scope of ``waters of the United States''
designed to meet that objective. This definition also ensures that
States have sole authority over waters that do not significantly affect
the paragraph (a)(1) waters clearly protected by the Act.
    As discussed elsewhere, this rule defines ``waters of the United
States'' to include tributaries, adjacent wetlands, and paragraph
(a)(5) waters that meet the relatively permanent or significant nexus
standards (see section IV.C of this preamble). This rule advances the
Clean Water Act's objective by helping restore and maintain the
chemical, physical, and biological integrity of traditional navigable
waters, the territorial seas, and interstate waters--waters of
longstanding and indisputable Federal interest--by protecting them from
degradation of upstream waters that significantly affect them. At the
same time, consistent with section 101(b), this rule recognizes,
preserves, and protects the rights and responsibilities of Tribes and
States by leaving within their purview all waters that do not
significantly affect the paragraph (a)(1) waters of paramount Federal
interest. The specific jurisdictional standards in this rule therefore
bear a relationship to the nature and extent of the Federal and Tribal
and State interests at play. This line-drawing highlights the agencies'
deliberate and due consideration of sections 101(a) and 101(b) in
developing this rule.
4. This Rule Is Both Generally Familiar and Implementable
    As described above in section IV.A of this preamble, the agencies
in this rule are interpreting ``waters of the United States'' to mean
the waters defined by the familiar 1986 regulations, with amendments to
reflect the agencies' determination of the statutory limits on the
scope of ``waters of the United States'' informed by the text of the
relevant provisions of the Clean Water Act and the statute as a whole,
the scientific record, relevant Supreme Court precedent, and the
agencies' experience and technical expertise after more than 45 years
of implementing the longstanding pre-2015 regulations defining ``waters
of the United States.'' It also reflects consideration of extensive
public comment.
    The agencies have extensive experience implementing the pre-2015
regulatory regime, as described further below in this section, and this
experience will assist the agencies in implementing this rule. The
agencies' approach to implementation of the relatively permanent and
significant nexus standards is broadly consistent with the pre-2015
regulatory regime, but the agencies have clarified and refined both the
regulatory text and the guidance on how the agencies intend to
implement these standards in order to promote consistent Clean Water
Act protections for waters. For additional

clarity, this rule includes a definition of ``significantly affect''
for purposes of applying the significant nexus standard. See section
IV.C of this preamble.
    Additionally, the agencies are codifying the two familiar and
longstanding exclusions from the definition of ``waters of the United
States'' for prior converted cropland and waste treatment systems and
adding exclusions for features that were generally considered non-
jurisdictional under the pre-2015 regulatory regime (see section IV.C.7
of this preamble). The features excluded under this rule were excluded
by regulation or generally considered non-jurisdictional in practice
under the pre-2015 regulatory regime and each of the subsequent rules
defining ``waters of the United States.''
    The agencies have extensive experience implementing the 1986
regulations. Moreover, the scientific and technical information
available to inform the significant nexus analysis and identify waters
that meet the relatively permanent standard has also markedly improved
over time and become more readily available since the agencies first
started implementing both standards. See section IV.G of this preamble.
Since the Court's decision in Rapanos, the agencies have gained more
than a decade of experience implementing the 1986 regulations
consistent with the relatively permanent standard and the significant
nexus standard under three different presidential Administrations,
beginning with the Rapanos Guidance issued in 2007. The agencies have
continued to implement the 1986 regulations consistent with the Rapanos
Guidance in response to court decisions.
    The agencies repromulgated the 1986 regulations in the 2019 Repeal
Rule and implemented those rules nationwide until June 22, 2020, when
the 2020 NWPR became effective. The agencies explained that with the
2019 Repeal Rule, they intended to ``restore the regulatory text that
existed prior to the 2015 Rule'' and that the agencies would
``implement the pre-2015 Rule regulations informed by applicable agency
guidance documents and consistent with Supreme Court decisions and
longstanding agency practice.'' 84 FR 56626 (October 22, 2019). The
agencies concluded that this approach ``will provide greater regulatory
certainty and national consistency while the agencies consider public
comments on the proposed [2020 NPWR].'' Id. at 56660. To further
justify a return to the 1986 framework, the agencies noted that ``[t]he
agencies, their co-regulators, and the regulated community are . . .
familiar with the pre-2015 Rule regulatory regime and have amassed
significant experience operating under those pre-existing regulations.
Agency staff in particular have developed significant technical
expertise in implementing the 1986 regulations.'' Id. The 2019 Repeal
Rule would thus ``provide greater certainty by reinstating nationwide a
longstanding regulatory framework that is familiar to and well-
understood by the agencies, States, Tribes, local governments,
regulated entities, and the public.'' Id. at 56661. Indeed, in their
comments to the 2019 Repeal Rule proposal, a number of regulators and
regulated parties alike expressed support for returning to the pre-2015
regulations, as implemented following SWANCC and Rapanos, due in part
to their experience and familiarity with that regime.\63\
---------------------------------------------------------------------------

    \63\ See, e.g., comments submitted by American Water Works
Association (August 13, 2018) (Docket ID: EPA-HQ-OW-2017-0203-
15559); comments submitted by North Dakota's Department of
Agriculture (July 25, 2018) (Docket ID: EPA-HQ-OW-2017-0203-15541);
comments submitted by the Office of the Governor of Utah (August 9,
2018) (Docket ID: EPA-HQ-OW-2017-0203-15202) (``Recodification of
the regulations that existed prior to the 2015 Rule will provide
continuity and certainty for regulated entities, States, the
agencies' staff, and the American public.'').
---------------------------------------------------------------------------

    Further, in responding to comments on the 2019 Repeal Rule proposal
asserting that the agencies should not return to the pre-2015
regulatory regime because that regime would reduce regulatory certainty
due to the prior regime's reliance on case-specific significant nexus
determinations, the agencies explained that ``[f]ollowing the Supreme
Court's decisions in SWANCC and Rapanos . . . the Corps published a
guidebook to assist district staff in issuing approved jurisdictional
determinations. In particular, the guidebook outlines procedures and
documentation used to support significant nexus determinations. This
guidebook has been and continues to be publicly available and will
continue to serve as a resource in issuing jurisdictional
determinations under this final rule.'' \64\ 84 FR 56660 (October 22,
2019). Even after the 2020 NWPR's June 22, 2020, effective date, the
agencies continued to implement the 2019 Repeal Rule consistent with
the Rapanos Guidance in Colorado until April 2021 due to litigation
barring implementation of the 2020 NWPR in that State.
---------------------------------------------------------------------------

    \64\ For convenience, EPA decisions on jurisdiction are referred
to as jurisdictional determinations throughout this document, but
such decisions are not ``approved jurisdictional determinations'' as
defined and governed by the Corps' regulations at 33 CFR 331.2.
---------------------------------------------------------------------------

    Like the past three presidential Administrations, courts have also
found that the 1986 regulations, implemented consistent with the
Rapanos standards, provide an appropriate regulatory framework to
implement the Clean Water Act. Indeed, in staying the 2015 Clean Water
Rule nationwide, the Sixth Circuit found that returning to the
``familiar, if imperfect, pre-Rule regime'' was the best path forward
pending judicial review of the 2015 Clean Water Rule. In re EPA & Dep't
of Def. Final Rule, 803 F.3d 804, 808 (6th Cir. 2015), vacated, 713
Fed. Appx. 489 (6th Cir. 2018). In doing so, the court recognized that
returning to the status quo meant returning to the pre-2015 regulatory
regime--not the 1986 regulations. See id. at 806 (finding that ``the
status quo at issue is the pre-[2015 Clean Water Rule] regime of
federal-state collaboration that has been in place for several years,
following the Supreme Court's decision in Rapanos''). Likewise, in
vacating the 2020 NWPR, the Arizona district court found that returning
to the pre-2015 regulatory regime would provide for a regime that ``is
familiar to the Agencies and industry alike.'' See Pascua Yaqui Tribe
v. EPA, 557 F. Supp. 3d 949, 956 (D. Ariz. 2021).
    The agencies acknowledge that the need for case-specific analyses
will continue under this rule for certain jurisdictional
determinations, potentially raising some timeliness and consistency
issues that the agencies' rules in 2015 and 2020 were designed, in
part, to reduce. The agencies' experience suggests that the number of
these analyses will be limited. Historically, only approximately 12% of
resources assessed in approved jurisdictional determinations using the
Rapanos Guidance required a significant nexus analysis.\65\ And those
significant nexus assessments often resulted in a conclusion that the
resource, either alone or in combination with similarly situated
waters, did not meet the significant nexus standard. Moreover, the
agencies have provided more clarity in this rule by: adding limitations
to the scope of the definition to the rule text; adding a definition of
``significantly affect'' that identifies the

functions and factors to be evaluated as part of a significant nexus
analysis; adding exclusions to the rule; restructuring and streamlining
the 1986 regulations; and drawing on more than a decade of post-Rapanos
implementation experience to provide additional implementation guidance
and resources. These improvements, taken together, substantially reduce
any inefficiencies that may be presented by the rule's case-specific
approach. Finally, as discussed above, the nature of the Clean Water
Act's requirements in general can be a fact-based, case-specific
inquiry and is not limited to whether a water meets the definition of
``waters of the United States.'' The inquiry is an important one, for
both discharges and the environment.
---------------------------------------------------------------------------

    \65\ It is the agencies' expectation that the number of
significant nexus analyses will increase under this rule due to the
assessment of paragraph (a)(5) waters under the significant nexus
standard, but the agencies do not expect a corresponding increase in
positive jurisdictional determinations. See section IV.C.6 of this
preamble for discussion of the agencies' intentions for
implementation of paragraph (a)(5).
---------------------------------------------------------------------------

    This rule is both consistent with the Clean Water Act's statutory
text and purposes and its framework is longstanding and familiar to
regulated parties and regulators alike. Moreover, all definitions of
``waters of the United States,'' including the 2020 NWPR, require some
level of case-specific analysis. Implementation of this rule will be
aided by improved and increased scientific and technical information
and tools that both the agencies and the public can use to determine
whether waters are ``waters of the United States'' (see section IV.G of
this preamble). Accordingly, the agencies have concluded that this rule
is consistent with the Clean Water Act and that its clarity and
familiar regulatory framework improve its implementability.
    Through the various rulemakings and court decisions relating to the
definition of ``waters of the United States'' since the Rapanos
decision in 2006, the agencies have continued implementing the 1986
regulations consistent with the Rapanos standards nationwide or in
numerous States across the country for various periods of time,
learning as they did so. This experience has allowed the agencies to
further develop expertise in implementing this regime. The agencies,
most often the Corps, have made hundreds of thousands of Clean Water
Act approved jurisdictional determinations since the issuance of the
Rapanos Guidance. Of those, tens of thousands have required a case-
specific significant nexus determination. The agencies have made such
determinations in every State in the country as well as in the U.S.
territories.
    With field staff located in 38 Corps District offices and 10 EPA
regional offices, the agencies have over a decade of nationwide
experience in making decisions regarding jurisdiction under the pre-
2015 regulatory regime consistent with the relatively permanent
standard and the significant nexus standard. Significant nexus
determinations have been made affirmatively for waters ranging from an
ephemeral stream that flows directly into a traditional navigable water
used extensively for recreational boating and fishing, to wetlands
adjacent to a perennial tributary and separated by a levee, to a non-
relatively permanent stream that provides flow to a drinking water
source, to a group of floodplain wetlands that provide important
protection from floodwaters to downstream communities alongside the
traditional navigable water, to headwater mountain streams that provide
high quality water that supplies baseflow and reduces the harmful
concentrations of pollutants in the main part of the river below. The
agencies have also made many findings of no jurisdiction under the 1986
regulations when they concluded the waters in question did not meet
either the relatively permanent standard or the significant nexus
standard as implemented by the Rapanos Guidance.
    Through this experience, the agencies developed wide-ranging
technical expertise in assessing the hydrologic flowpaths along which
water and materials are transported and transformed and that determine
the degree of chemical, physical, or biological connectivity and
effects to paragraph (a)(1) waters. The agencies have also become
deeply familiar with the variations in climate, geology, and terrain
within and among watersheds that affect the functions (such as the
transformation or filtering of pollutants) performed by streams, open
waters, and wetlands for paragraph (a)(1) waters.
    The agencies utilize many tools and many sources of information to
help support decisions on jurisdiction, including U.S. Geological
Survey (USGS) and State and local topographic maps, aerial photography,
satellite imagery, gage data, soil surveys, National Wetlands Inventory
maps, floodplain maps, watershed studies, modeling tools, scientific
literature and references, and field work. As discussed further in
section IV.G of this preamble, these tools have undergone important
technological advances and have become increasingly available since the
Rapanos decision. For example, USGS, State, and local stream maps and
datasets, aerial photography, gage data, watershed assessments,
monitoring data, and field observations are often used to help assess
the flow contributions of tributaries, including intermittent and
ephemeral streams, to downstream traditional navigable waters, the
territorial seas, or interstate waters. Similarly, floodplain and
topographic maps from Federal, State, and local agencies, modeling
tools, and field observations can be used to assess how wetlands are
storing floodwaters that might otherwise affect the integrity of
paragraph (a)(1) waters. Further, the agencies utilize the large body
of scientific literature regarding the functions of tributaries,
including tributaries with ephemeral, intermittent, and perennial flow,
and of wetlands and open waters to inform their significant nexus
analyses. In addition, the agencies have experience and expertise from
decades of making decisions on jurisdiction that considered hydrology,
ordinary high water mark (OHWM) and its associated indicators (see
section IV.C.8.d of this preamble), biota, and other technical factors
in implementing Clean Water Act programs. The agencies' immersion in
the science, along with the practical expertise developed over more
than a decade of case-specific determinations across the country, have
helped the agencies determine which waters have a significant nexus and
where to draw boundaries demarking the ``waters of the United States.''
    Regulated entities and other interested parties also have
substantial experience with the 1986 regulations and the two Rapanos
standards. As the agencies have developed their expertise in
implementing this regime, so have State and Tribal co-regulators and
regulated entities, as well as interested citizens who may play an
important role in the Act's permitting process. Individuals uncertain
about the status of waters on their property may obtain a
jurisdictional determination from the Corps. The Corps does not charge
a fee for this service. See 33 CFR 325.1; Regulatory Guidance Letter
16-01 (2016).
    Due in part to the familiarity of this regime, this rule will not
undermine serious reliance interests in an alternative regime,
including the 2020 NWPR, which the agencies have not implemented for
over a year following the Arizona district court's August 30, 2021
vacatur order. The Supreme Court has held that agencies' changes in
position do not require any reasons ``more substantial than those
required to adopt a policy in the first instance.'' FCC v. Fox
Television Stations, Inc., 556 U.S. 502, 514 (2009). The Court
acknowledged that if an agency's ``prior policy has engendered serious
reliance interests,'' id. at 515, those interests cannot be ignored.
However, the Court emphasized that even in the case of ``serious
reliance interests,'' ``further

justification'' beyond a ``reasoned explanation . . . for disregarding
facts and circumstances that underlay or were engendered by the prior
policy'' is not needed. Id. at 515-16. This rule does not implicate
serious reliance interests because, first, the agencies are codifying a
rule similar to the definition currently being implemented nationwide.
As discussed in section V.A of this preamble, this rule will establish
a regime that is generally comparable to current practice, and this
rule is expected to generate de minimis costs and benefits as compared
to the pre-2015 regulatory regime that the agencies are currently
implementing. Second, members of the public, Tribes, and States have
been aware that the agencies might reconsider the 2020 NWPR since
January 2021 and have had many opportunities to share their views with
the agencies. President Biden indicated on his first day in office,
following the issuance of Executive Order 13990, that this
administration would be reviewing the 2020 NWPR and deciding whether to
revise or replace the rule. See section III.B.5 of this preamble. On
June 9, 2021, the agencies announced their intention to revise or
replace the rule. The agencies subsequently embarked on an extensive
stakeholder outreach process, including public meetings and federalism
and Tribal consultations. See section III.C of this preamble. The
agencies received over 32,000 recommendation letters from the public
during pre-proposal outreach and over 114,000 comments on the proposed
rule during the public comment period. The agencies also held a public
hearing and multiple listening sessions with Tribal, State, and local
governments during the public comment period to listen to feedback on
the proposed rule from co-regulators and a variety of stakeholders.
    Third, the 2020 NWPR was only in effect for approximately 14 months
before it was vacated by the Arizona district court on August 30, 2021.
See Pascua Yaqui Tribe v. EPA, 557 F. Supp. 3d 949 (D. Ariz. 2021).
Less than a month later, another district court issued an order
vacating the 2020 NWPR on September 27, 2021. Navajo Nation v. Regan,
563 F. Supp. 3d 1164 (D.N.M. 2021). And several other district courts
remanded the 2020 NWPR without vacatur or without addressing vacatur in
six additional cases, starting in July 2021.\66\ Following the vacatur
orders, the agencies clarified that the Corps will no longer rely on
approved jurisdictional determinations issued under the 2020 NWPR in
making new permit decisions--although so-called ``stand-alone''
approved jurisdictional determinations (i.e., those that are not
associated with a permit action) will not be reopened prior to their
expiration date unless one of the criteria for revision is met or if
the recipient requests that the Corps provide a new approved
jurisdictional determination. See section IV.F of this preamble for
further discussion of the status of approved jurisdictional
determinations issued under prior rules.
---------------------------------------------------------------------------

    \66\ Order, Pueblo of Laguna v. Regan, No. 1:21-cv-00277, ECF
No. 40 (D.N.M. Sept. 21, 2021) (declining to reach issue of vacatur
in light of the Pascua decision); Order, California v. Wheeler, No.
3:20-cv-03005, ECF No. 271 (N.D. Cal. Sept. 16, 2021) (same); Order,
Waterkeeper All., Inc. v. Regan, No. 3:18-cv-03521, ECF No. 125
(N.D. Cal. Sept. 16, 2021) (same); Order, Conservation L. Found. v.
EPA, No. 1:20-cv-10820, ECF No. 122 (D. Mass. Sept. 1, 2021) (same);
Order, S.C. Coastal Conservation League v. Regan, No. 2:20-cv-01687,
ECF No. 147 (D.S.C. July 15, 2021) (remanding without vacating);
Order, Murray v. Wheeler, No. 1:19-cv-01498, ECF No. 46 (N.D.N.Y.
Sept. 7, 2021) (same).
---------------------------------------------------------------------------

    Interested parties have thus had over a year to adapt to operating
under the pre-2015 regulatory regime in the absence of the 2020 NWPR,
including ample notice of the implications of the 2020 NWPR's vacatur
on the validity of approved jurisdictional determinations issued
thereunder. Moreover, as discussed in this section, members of the
public are familiar with this rule's regulatory framework thereby
minimizing the potential disruption of a change. Finally, even if
serious reliance interests were at issue, which they are not, this rule
provides a thorough and reasoned explanation for the changed definition
of ``waters of the United States.''
5. Public Comments Received and Agency Responses
    The agencies received numerous comments on the basis for the
proposed rule, including comments about the proposal's consistency with
the statute and Supreme Court decisions and about the proposal's
approach to various categories of waters. The agencies have fully
considered these timely comments and made changes to the rule to
reflect the comments, as discussed below. This section contains
summaries of these comments and the agencies' general responses; a more
comprehensive response to these comments is in the response to comments
document available in the docket for this rule at Docket ID No. EPA-HQ-
OW-2021-0602.
a. Comments Regarding Consistency of the Proposed Rule With the Text of
the Clean Water Act
    Many commenters stated that the proposed rule is consistent with
the Clean Water Act's objective in section 101(a) to restore and
maintain the chemical, physical, and biological integrity of the
nation's waters and provided multiple reasons to support that view,
including the statutory text, legislative history, and science. Some
commenters further asserted that the statute requires the agencies to
regulate waters in addition to traditional navigable waters, the
territorial seas, and interstate waters.
    The agencies agree that the definition of ``waters of the United
States'' must be designed to advance the objective of the Clean Water
Act. For the reasons discussed in section IV.A.2 and IV.A.3 of this
preamble, the agencies also interpret the Act based on factors other
than the science and connectivity of waters, including the text of the
statute as a whole and relevant Supreme Court decisions. Further, while
the definition of ``waters of the United States'' is designed to
advance the objective of restoring and maintaining the chemical,
physical, and biological integrity of traditional navigable waters, the
territorial seas, and interstate waters--i.e., the paragraph (a)(1)
waters--this rule covers additional waters that must be protected to
safeguard paragraph (a)(1) waters. All ``waters of the United States''
receive the full protections of the Clean Water Act.
    Commenters expressed various views on the import of the word
``navigable'' in the statutory term ``navigable waters.'' Some
commenters asserted that the proposed rule did not give enough effect
to the word ``navigable,'' while others suggested that the agencies'
jurisdiction over ``waters of the United States'' is limited to
traditional navigable waters. Further, some commenters stated that
Congress intended to exercise only its traditional commerce power over
navigation rather than the full extent of its authority under the
Commerce Clause. In contrast, other commenters asserted that
legislative history demonstrates Congress's intent to assert broad
jurisdiction under the Clean Water Act beyond navigable-in-fact waters.
    The agencies agree that while the Clean Water Act applies to
``navigable waters,'' Congress also broadly defined that term to
include ``the waters of the United States.'' 33 U.S.C. 1362(7). The
breadth of that definition reflects a deliberate choice. The relevant
House bill would have defined ``navigable

waters'' as the ``navigable waters of the United States, including the
territorial seas.'' H.R. Rep. No. 92-911, 92d Cong., 2d Sess. 356
(1972). But in conference the word ``navigable'' was deleted from that
definition, and the conference report urged that the term ``be given
the broadest possible constitutional interpretation.'' S. Conf. Rep.
No. 92-1236, 92d Cong., 2d Sess. 144 (1972). Additionally, the agencies
disagree that Clean Water Act jurisdiction is limited to traditional
navigable waters, as this interpretation would render the Clean Water
Act narrower than the Rivers and Harbors Act of 1899. Limiting Clean
Water Act jurisdiction to traditional navigable waters is also contrary
to the views of all nine Supreme Court Justices in Rapanos and would
undo Congress's considered and deliberate choice to expand Clean Water
Act jurisdiction beyond traditional navigable waters because it found
the prior statutes limited to those waters insufficient. Indeed, the
Rapanos plurality recognized that a wetland may be treated as a covered
water if it has a continuous surface connection to a ``relatively
permanent'' tributary that ``connect[s] to'' traditional navigable
waters, without any further inquiry into the tributary's navigability
or status as a link in a channel of commerce. 547 U.S. at 742. The
plurality further observed that the 1977 Clean Water Act's
authorization for States to administer the section 404 program for
``navigable waters . . . other than'' those used or suitable for use
``to transport interstate or foreign commerce,'' id. at 731 (quoting 33
U.S.C. 1344(g)(1)), ``shows that the Act's term `navigable waters'
includes something more than traditional navigable waters.'' Id.
(citing SWANCC, 531 U.S. at 167; Riverside Bayview, 474 U.S. at 133).
And neither Justice Kennedy nor the dissenting Justices in Rapanos
endorsed such a jurisdictional limitation. See id. at 782-83 (Kennedy,
J., concurring in the judgment); id. at 807-08 (Stevens, J.,
dissenting).
    The agencies are mindful of the Supreme Court's decision in SWANCC
regarding the specific Commerce Clause authority Congress exercised in
enacting the Clean Water Act. The SWANCC Court observed that Congress
signified its intent to exercise its commerce power over navigation
with the statement in the Conference Report for the Clean Water Act
that the conferees ``intend that the term `navigable waters' be given
the broadest possible constitutional interpretation.'' 531 U.S. at 168
n.3 (citing S. Conf. Rep. No. 92-1236, at 144 (1972)). This rule
ensures that waters that either alone or in combination significantly
affect the integrity of traditional navigable waters, the territorial
seas, or interstate waters are protected under the Clean Water Act, and
the Supreme Court has long held that authority over traditional
navigable waters is not limited to either protection of navigation or
authority over only the traditional navigable water. Rather, the Court
has found that ``the authority of the United States is the regulation
of commerce on its waters . . . [f]lood protection, watershed
development, [and] recovery of the cost of improvements through
utilization of power are likewise parts of commerce control.'' United
States v. Appalachian Elec. Power Co., 311 U.S. 377, 426 (1940); see
also Oklahoma ex rel. Phillips v. Guy F. Atkinson Co., 313 U.S. 508,
525-26 (1941) (``[J]ust as control over the non-navigable parts of a
river may be essential or desirable in the interests of the navigable
portions, so may the key to flood control on a navigable stream be
found in whole or in part in flood control on its tributaries. . . .
[T]he exercise of the granted power of Congress to regulate interstate
commerce may be aided by appropriate and needful control of activities
and agencies which, though intrastate, affect that commerce.''
(citations omitted)). The significant nexus standard included in this
final rule ensures that the definition of ``waters of the United
States'' remains well within the bounds of the Commerce Clause,
consistent with the text of the statute and the intent of Congress, and
informed by the decision in SWANCC.
    Some commenters suggested that the agencies cannot rely on the
Clean Water Act's statutory objective or on science to expand Federal
jurisdiction beyond the authority granted to the agencies by Congress.
However, this final rule does not establish jurisdiction beyond the
scope of the Clean Water Act. Indeed, as discussed in section IV.A of
this preamble, the agencies conclude that the objective of the Clean
Water Act must be considered in defining ``waters of the United
States'' and that consideration of the objective of the Act for
purposes of a rule defining ``waters of the United States'' must
include substantive consideration of the effects of a revised
definition on the integrity of the nation's waters. And since the
objective of the Clean Water Act is to protect the water quality of the
nation's waters, this rule must be informed by science relevant to
water quality, as discussed in section IV.A.2.a of this preamble. At
the same time, the agencies do not interpret the objective of the Clean
Water Act to be the only factor relevant to determining the scope of
the Act; rather, the limitations established in this rule are based on
the agencies' consideration of the text of the relevant provisions of
the Clean Water Act and the statute as a whole, the scientific record,
relevant Supreme Court case law, and the agencies' experience and
technical expertise after more than 45 years of implementing the
longstanding pre-2015 regulations defining ``waters of the United
States.'' The agencies thus have established a definition of ``waters
of the United States'' within the authority granted to the agencies by
Congress.
    Commenters also expressed various views about the import of Clean
Water Act section 101(b). Some commenters asserted that the agencies
must read sections 101(a) and 101(b) of the Clean Water Act together in
a manner that recognizes States' traditional authority over their water
resources and contended that the agencies did not adequately consider
section 101(b) in developing the proposed rule. In contrast, other
commenters asserted that section 101(b) is not intended to serve as a
limit on Federal jurisdiction, and some of these commenters further
suggested that the agencies improperly relied on section 101(b) to
limit the scope of ``waters of the United States'' in the proposed
rule. As discussed in section IV.A of this preamble and section V.A of
the preamble to the proposed rule, the agencies have carefully, and
appropriately, balanced consideration of sections 101(a) and 101(b) in
deciding in the rulemaking which waters are subject to Clean Water Act
jurisdiction.
    Additionally, multiple commenters asserted that a water that is not
subject to Federal jurisdiction does not necessarily lack environmental
protections because such waters may be subject to Tribal, State, or
local regulations. Relatedly, some commenters suggested that improving
and maintaining water quality is best achieved through partnerships and
that the agencies should work with State and local governments in
developing a definition of ``waters of the United States.'' The
agencies recognize that waters that are not jurisdictional under the
Clean Water Act do not necessarily lack environmental protections under
potential Tribal, State, or local laws. However, Congress enacted the
Clean Water Act precisely because of the failures of a statutory scheme
that relied primarily on State water quality standards. In 1948,
Congress enacted the Federal Water Pollution Control Act, ch.

758, 62 Stat. 1155 (June 30, 1948), which focused on State water
quality standards rather than the conduct of individual polluters. See
EPA v. California ex rel. State Water Res. Control Bd., 426 U.S. 200,
202-03 (1976). In 1972, Congress enacted the Clean Water Act after
concluding that these prior efforts had been ``inadequate in every
vital aspect.'' S. Rep. No. 414, 92d Cong., 1st Sess. 7 (1971). The
Clean Water Act was a `` `complete rewriting' '' of existing law,
designed to ``establish an all-encompassing program of water pollution
regulation.'' City of Milwaukee, 451 U.S at 317-18 (1981) (citation
omitted).
    More recently, the Supreme Court in Maui identified a key dividing
line between the areas where Congress intended to create a
comprehensive floor of Federal water quality protections and those
areas generally left to the States, observing that ``the structure of
the [Clean Water Act] indicates that, as to groundwater pollution and
nonpoint source pollution, Congress intended to leave substantial
responsibility and autonomy to the States.'' 140 S. Ct. at 1471 (citing
Clean Water Act section 101(b)). The Clean Water Act thus sets a
baseline of Federal protection for waters that meet the definition of
``waters of the United States'' and authorizes States to be more
protective than the Act while also leaving substantial responsibility
and autonomy to the States over those waters that do not have a
significant nexus to the core waters covered by the Act. The agencies
also agree that partnerships with Tribes, States, and local governments
are important and can help facilitate meeting the objective of the Act
and have coordinated with these entities over the course of this
rulemaking to ensure that they had opportunities to provide input on
this rule and will continue to work with Tribes and States to implement
this rule.
b. Comments Regarding Supreme Court Case Law and the Significant Nexus
and Relatively Permanent Standards
    Many commenters addressed the legal standard for determining the
controlling opinion in Rapanos. In particular, many commenters cited
Marks v. United States, 430 U.S. 188 (1977) to support assertions
around what controlling legal principles may be derived from the
opinion of five or more Supreme Court Justices when there is no
majority. Relying on Marks, some of these commenters asserted that the
Rapanos plurality opinion should control the definition of ``waters of
the United States,'' while other commenters stated that Marks allows
for use of either the plurality's relatively permanent standard or
Justice Kennedy's significant nexus standard to assess Clean Water Act
jurisdiction. As discussed above, the applicability of Marks is not the
relevant inquiry for purposes of this rule. Rather, this rule reflects
the agencies' interpretation of the statute, informed by Supreme Court
precedent, not an interpretation of the Rapanos decision.