Waters of the United States (WOTUS): Frequently Asked Questions About the Scope of the Clean Water Act

Waters of the United States (WOTUS): Frequently Asked Questions About the Scope of the Clean Water Act

Waters of the United States (WOTUS):
June 22, 2023
Frequently Asked Questions About the Scope
Kate R. Bowers
of the Clean Water Act
Legislative Attorney

Congress established the Federal Water Pollution Control Act, also known as the Clean Water
Laura Gatz
Act (CWA), to restore and protect the quality of the nation’s surface waters. The CWA protects
Specialist in Environmental
“navigable waters,” defined in the statute as “waters of the United States, including the territorial
Policy
seas.” The CWA does not further define the term waters of the United States (WOTUS), which

determines which waters are federally regulated. Thus, in implementing the CWA, the Army
Corps of Engineers (Corps) and the Environmental Protection Agency (EPA)—the two agencies

that administer the statute—have defined the term in regulations. However, Congress’s intent as
to the meaning of WOTUS has been debated and litigated for more than four decades. The Supreme Court and lower courts
have also weighed in on the scope of the term.
For much of the past several decades, regulations promulgated by the Corps and EPA in the 1980s have been in effect.
(These regulations, as further interpreted by the courts and agencies are often referred to as the pre-2015 rules.) The agencies
supplemented these regulations with guidance, which they developed in response to prior Supreme Court rulings related to
the scope of the federal government’s ability to regulate WOTUS. The Corps and EPA acknowledged that their guidance did
not provide the public or agency staff with the information needed to ensure timely, predictable, and consistent jurisdictional
determinations. Diverse stakeholders and Members of Congress requested a formal rulemaking to revise existing regulations.
Successive presidential administrations have engaged in efforts to define WOTUS in regulation. Both the Obama
Administration’s 2015 Clean Water Rule and the Trump Administration’s 2020 Navigable Waters Protection Rule prompted
strong reactions from a variety of stakeholders, with numerous groups filing lawsuits challenging the rules. On January 18,
2023, the Corps and EPA, under the Biden Administration, issued a new rule (the 2023 WOTUS Rule) redefining WOTUS in
the agencies’ regulations. The Corps and EPA asserted that their intent in promulgating the 2023 WOTUS Rule was to
redefine WOTUS in a durable regulation, updating the pre-2015 rules to reflect consideration of past Supreme Court
decisions, science, and the agencies’ experience and technical expertise. In general, the rule defines WOTUS more narrowly
than the Clean Water Rule and more broadly than the Navigable Waters Protection Rule.
The 2023 WOTUS Rule went into effect on March 20, 2023, and was immediately challenged. Three courts have stayed
implementation of the 2023 WOTUS Rule in a total of 27 states and as applied to several associations that are participating in
the litigation. For those states and plaintiffs, the Corps and EPA are interpreting WOTUS consistent with the pre-2015
framework. While some stakeholders support the 2023 WOTUS Rule, others believe it defines WOTUS too broadly, does not
provide regulatory clarity, and should not have been issued prior to the resolution of a Supreme Court case that was pending
at the time the rule was promulgated.
In June 2023, that Supreme Court case—Sackett v. EPA—was decided. The majority in Sackett formally adopted the
approach taken by a four-Justice plurality in the 2006 case Rapanos v. United States and rejected elements of the
jurisdictional test that are present in the 2023 WOTUS Rule. While many questions about the implications of the Court’s
decision remain, the ruling significantly narrows the scope of WOTUS in comparison not only to the 2023 WOTUS Rule but
also to any of the regulations the agencies have promulgated to define WOTUS.
In the 118th Congress, Members have introduced legislation pertaining to WOTUS, including a joint resolution to revoke the
2023 WOTUS Rule through the Congressional Review Act, which passed both chambers but was vetoed by the President.
Members have also introduced legislation to define the term through amendments to the CWA. Looking forward, Congress
may seek to oversee the Biden Administration’s efforts to implement the Supreme Court’s decision in Sackett v. EPA or may
consider introducing legislation to define the scope of WOTUS if it seeks to clarify its intent as to the scope of the term.
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Contents
What Actions Have Previous Administrations Taken to Define WOTUS? ..................................... 2
Pre-2015 Rules and Guidance ................................................................................................... 2
2015 Clean Water Rule.............................................................................................................. 3
2020 Navigable Waters Protection Rule ................................................................................... 4
How Does the 2023 WOTUS Rule Define WOTUS? ..................................................................... 5
Jurisdictional Waters (WOTUS) ............................................................................................... 5
Traditional Navigable Waters, the Territorial Seas and Interstate Waters
(Paragraph (a)(1) Waters) ................................................................................................ 6
Impoundments of Jurisdictional Waters .............................................................................. 6
Tributaries, Adjacent Wetlands, and “Additional Waters” .................................................. 7
Exclusions ................................................................................................................................. 8
Definitions ................................................................................................................................. 9
Which Rule Is in Effect Now? ....................................................................................................... 10
Has the 2023 WOTUS Rule Been Challenged in Court? .............................................................. 12
How Does Sackett v. EPA Affect the Scope of CWA Jurisdiction? ............................................... 14
How Have Adjacent Wetlands Been Addressed in Prior WOTUS Regulations? .......................... 16
What Options Are Available to Congress Regarding the Definition of WOTUS? ........................ 20

Figures
Figure 1. Status of 2023 WOTUS Rule as of June 22, 2023 .......................................................... 11

Tables
Table 1. Jurisdictional Waters (WOTUS) Under the 2023 WOTUS Rule ....................................... 5
Table 2. Scope of Adjacent Wetlands Under Waters of the United States (WOTUS)
Regulations, Guidance, and in the Sackett v. EPA Decision ....................................................... 17

Contacts
Author Information ........................................................................................................................ 21

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Waters of the United States (WOTUS): Frequently Asked Questions

ongress established the Federal Water Pollution Control Act, also known as the Clean
Water Act (CWA), to restore and protect the quality of the nation’s surface waters.1 The
C Clean Water Act protects “navigable waters,” defined in the statute as “waters of the
United States, including the territorial seas.”2 The CWA does not define waters of the United
States (WOTUS). The scope of the term determines which waters are federally regulated, and
thus which waters are subject to CWA requirements and programs. These include CWA
permitting requirements; water quality certifications; water quality standards, impaired waters,
and total maximum daily loads; and other CWA and non-CWA programs.
Successive Administrations have struggled to interpret the term waters of the United States for the
purpose of implementing various requirements of the CWA. Prior to the Biden Administration,
executive branch efforts to define WOTUS administratively included regulations promulgated by
the Army Corps of Engineers (Corps) and the Environmental Protection Agency (EPA) in the
1980s and supplemented with interpretive guidance developed in response to Supreme Court
rulings; the 2015 Clean Water Rule; and the 2020 Navigable Waters Protection Rule.3 The
agencies’ efforts to define WOTUS in regulation during both the Obama and Trump
Administrations were controversial and led to litigation. Many observers viewed the Obama
Administration’s 2015 Clean Water Rule as defining WOTUS too broadly, while many viewed
the Trump Administration’s 2020 Navigable Waters Protection Rule as defining WOTUS too
narrowly. A federal district court vacated the 2020 Navigable Waters Protection Rule in
September 2021, after which the Corps and EPA announced that they had halted implementation
of the rule.4
On January 18, 2023, the Corps and EPA published a new rule (the 2023 WOTUS Rule) revising
the definition of WOTUS.5 The agencies asserted that their intent in promulgating the 2023
WOTUS Rule was to redefine WOTUS in a durable regulation, updating the pre-2015 rules to
reflect consideration of Supreme Court decisions, science, and the agencies’ experience and
technical expertise.6 Some stakeholders supported the 2023 WOTUS Rule, in some cases
observing that the rule takes a middle road between the 2015 Clean Water Rule and the 2020
Navigable Waters Protection Rule.7 Others expressed opposition to the 2023 WOTUS Rule,
arguing that it does not provide regulatory clarity, is overly broad, and that the Corps and EPA
should have delayed issuing a rule pending the resolution of Sackett v. EPA, a Supreme Court case
addressing aspects of the scope of WOTUS.

1 33 U.S.C. § 1251 et seq.
2 33 U.S.C. § 1362(7).
3 Army Corps of Engineers and EPA, “Clean Water Rule: Definition of ‘Waters of the United States’; Final Rule,” 80
Federal Register 37054, June 29, 2015 (hereinafter “2015 Clean Water Rule”); Army Corps of Engineers and EPA,
“The Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’” 85 Federal Register 22250, Apr.
21, 2020 (hereinafter “Navigable Waters Protection Rule”).
4 Pascua Yaqui Tribe v. EPA, 557 F. Supp. 3d 949 (D. Ariz. 2021).
5 Revised Definition of “Waters of the United States,” 88 Federal Register 3004, Jan. 18, 2023 (hereinafter “2023
WOTUS Rule”). The final rule was published on Jan. 18, 2023. The agencies released a pre-publication version of the
rule on Dec. 30, 2022.
6 2023 WOTUS Rule, p. 3019. See also Corps and EPA, Final Rule: Revised Definition of ‘Waters of the United States’
Fact Sheet, Dec. 2022, https://www.epa.gov/system/files/documents/2022-12/Public%20Fact%20Sheet.pdf (hereinafter
“2022 WOTUS Fact Sheet”).
7 See, for example, David LaRoss, “Touting ‘Durable’ Approach, EPA Adopts Dual Tests in Revised WOTUS Rule,”
InsideEPA.com, Dec. 30, 2022.
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Waters of the United States (WOTUS): Frequently Asked Questions

The 2023 WOTUS Rule went into effect on March 20, 2023, and was immediately challenged.8
While no court has issued a ruling on the merits of the rule, some courts have issued orders
temporarily barring implementation of the rule while litigation is pending. In the 27 states and as
to the associations and their members that are covered by those orders, the Corps and EPA are
interpreting WOTUS consistent with the pre-2015 regulatory framework. Apart from the pending
litigation challenging the 2023 WOTUS Rule, in May 2023, the Supreme Court issued its ruling
in Sackett v. EPA. In Sackett, the Court construed the reach of the CWA more narrowly than the
new or previous regulatory interpretations or the approach adopted by the courts of appeals
following an earlier Supreme Court decision regarding WOTUS. While the Corps and EPA have
not indicated what steps they will take to implement the Court’s decision, the limitations imposed
by the Court’s ruling cast doubt on the continued validity of the 2023 WOTUS Rule. Many
questions about the implications of the Court’s decision remain, but the ruling significantly
narrows the scope of WOTUS in comparison to any of the regulations the agencies have
promulgated to define WOTUS.
This report addresses frequently asked questions about WOTUS, including actions taken by prior
administrations, the 2023 WOTUS Rule, the Supreme Court’s ruling in Sackett v. EPA, potential
implications of the ruling, and options for Congress.
What Actions Have Previous Administrations Taken
to Define WOTUS?
Pre-2015 Rules and Guidance
For much of the past several decades, regulations promulgated by the Corps and EPA in 1986 and
1988, respectively, have been in effect.9 The agencies have supplemented these regulations with
interpretive guidance developed in response to Supreme Court rulings related to the scope of the
federal government’s ability to regulate WOTUS.10
One such Supreme Court case remains particularly relevant to the most recent efforts to redefine
WOTUS. In Rapanos v. United States, the Court considered the extent of CWA jurisdiction over
wetlands near ditches or man-made drains that emptied into traditional navigable waters.11 The
Court’s decision in Rapanos yielded three different opinions, none of which garnered a
controlling majority for a single standard to govern future jurisdictional disputes. Instead, the
decision resulted in two alternative tests for evaluating jurisdictional waters: a “relatively
permanent” test set forth by a four-Justice plurality in an opinion authored by Justice Antonin

8 Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex.); West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D.); Kentucky v.
EPA, No. 3:23-cv-00007 (E.D. Ky.).
9 Army Corps of Engineers, “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal Register
41206, Nov. 13, 1986 (hereinafter “1986 Corps Rule”); EPA, “Clean Water Act Section 404 Program Definitions and
Permit Exemptions; Section 404 State Program Regulations,” 53 Federal Register 20764, June 6, 1988 (hereinafter
“1988 EPA Rule").
10 Army Corps of Engineers and EPA, “Appendix A, Joint Memorandum,” 68 Federal Register 1995, Jan. 15, 2003;
Benjamin H. Grumbles, Assistant Administrator for Water, EPA, and John Paul Woodley Jr., Assistant Secretary of the
Army (Civil Works), Department of the Army, Clean Water Act Jurisdiction Following the U.S. Supreme Court’s
Decision in Rapanos v. United States & Carabell v. United States, memorandum, Dec. 2, 2008 (hereinafter “2008
Rapanos Guidance”).
11 547 U.S. 715 (2006).
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Waters of the United States (WOTUS): Frequently Asked Questions

Scalia, and a “significant nexus” test proposed by Justice Anthony Kennedy in a concurring
opinion.
Rapanos and the Relatively Permanent and Significant Nexus Tests
The Plurality’s “Relatively Permanent” Test: Writing for a four-Justice plurality, Justice Scalia wrote that
the word “waters” in “waters of the United States” means only “relatively permanent, standing or continuously
flowing bodies of water”—that is, streams, rivers, and lakes.12 Wetlands could be included only when they have a
“continuous surface connection” to such waters.13
Justice Kennedy’s “Significant Nexus” Test: In a concurring opinion joined by no other Justice, Justice
Kennedy wrote that the Corps should determine on a case-by-case basis whether wetlands have a “significant
nexus” to traditionally navigable waters based on whether the wetland, either alone or in connection with similarly
situated properties, significantly impacts the chemical, physical, and biological integrity of a traditionally navigable
water.14
In response to the rulings, the agencies developed guidance to help clarify how EPA and Corps
offices should implement the Court’s decisions. In particular, the agencies expressed the view that
waters meeting either the relatively permanent standard articulated by Justice Scalia, or the
significant nexus standard articulated by Justice Kennedy, were subject to federal jurisdiction
under the act.15 However, the Corps and EPA acknowledged that their written guidance did not
provide the public or agency staff with the information needed to ensure timely, predictable, and
consistent jurisdictional determinations.16 Diverse stakeholders—including Members of
Congress, states, the regulated community, and nongovernmental organizations—requested a
formal rulemaking to revise the existing rules.17
2015 Clean Water Rule
In 2015, the Corps and EPA issued the Clean Water Rule, which redefined WOTUS in the
agencies’ regulations for the first time since the 1980s.18 The Clean Water Rule retained aspects of
the agencies’ earlier guidance and also incorporated new features, including a new definition of
tributaries and definitions and criteria related to adjacency.19
Some stakeholders and observers viewed the Clean Water Rule as an expansion of CWA
jurisdiction, while others argued that it excluded too many waters from federal jurisdiction.20
Numerous parties challenged the Clean Water Rule, and some district courts issued preliminary
injunctions temporarily barring the Clean Water Rule from taking effect in certain states.21 Two

12 Id. at 739.
13 Id. at 742.
14 Id. at 782 (Kennedy, J., concurring).
15 2008 Rapanos Guidance; see also Rapanos, 547 U.S. at 810 (Stevens, J., dissenting).
16 2015 Clean Water Rule, p. 37056.
17 See EPA Web Archive at https://archive.epa.gov/epa/cleanwaterrule/what-clean-water-rule-does.html, which
includes a list of stakeholders requesting a rulemaking (https://archive.epa.gov/epa/sites/production/files/2014-03/
documents/wus_request_rulemaking.pdf).
18 2015 Clean Water Rule.
19 2015 Clean Water Rule, pp. 37057-37059, 37105-37106.
20 See, for example, Carolina Bolado, “Fla., Others Sue EPA, Corps Over Clean Water Act Expansion,” Law360, June
30, 2015; Center for Biological Diversity, “EPA and Army Corps Issue Weak Clean Water Rule,” press release, May
27, 2015, https://www.biologicaldiversity.org/news/press_releases/2015/clean-water-rule_05-27-2015.html.
21 North Dakota v. EPA, 127 F. Supp. 3d 1047 (D.N.D. 2015); Georgia v. Pruitt, 326 F. Supp. 3d 1356 (S.D. Ga. 2018);
Texas v. EPA, No. 3:15-cv-162, 2018 WL 4518230 (S.D. Tex. Sept. 12, 2018); Or. Cattlemen’s Ass’n v. EPA, No. 19-
00564 (D. Or. July 26, 2019).
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courts also remanded the rule to the Corps and EPA, concluding that it violated the
Administrative Procedure Act (APA) and exceeded the agencies’ statutory authority under the
CWA.22 As a result, until its rescission, the Clean Water Rule was in effect in a patchwork of
states. In states that were subject to a preliminary injunction or an order remanding the rule to the
Corps and EPA, the pre-2015 regulatory framework applied.
2020 Navigable Waters Protection Rule
The Trump Administration described the Clean Water Rule as an example of federal “overreach,”
and the Corps and EPA engaged in a two-step process to rescind and revise it.23 In Step One, the
Corps and EPA rescinded the Clean Water Rule and recodified the pre-2015 regulations.24
Accordingly, the pre-2015 regulations and guidance were in effect beginning on the effective date
of the Step One Rule (December 23, 2019), and until the agencies’ redefinition of WOTUS went
into effect. In April 2020, the Corps and EPA published a final Step Two Rule to redefine
WOTUS, titled the Navigable Waters Protection Rule.25 The rule went into effect on June 22,
2020, replacing the Step One Rule.
Overall, the Navigable Waters Protection Rule narrowed the scope of waters and wetlands that
were considered WOTUS (and were therefore under federal jurisdiction) compared to both the
Clean Water Rule and the pre-2015 rules. As with the Clean Water Rule, the Navigable Waters
Protection Rule prompted a range of reactions from a variety of stakeholders and resulted in
many lawsuits around the country.
President Biden signaled interest in reconsidering the Navigable Waters Protection Rule
immediately upon taking office.26 After announcing in June 2021 that they intended to revise the
definition of WOTUS again, the Corps and EPA asked courts where legal challenges to the
Navigable Waters Protection Rule were pending to remand the rule while they developed a new
regulation.27
On August 30, 2021, the U.S. District Court for the District of Arizona granted the agencies’
request for voluntary remand, but also vacated the rule.28 While the court did not issue a ruling on
the merits of the Navigable Waters Protection Rule, it found that both the plaintiffs and the United
States had identified concerns with the rule that involved fundamental, substantive, and incurable

22 Georgia v. Wheeler, 418 F. Supp. 3d 1336 (S.D. Ga. 2019); Texas v. EPA, 389 F. Supp. 3d 497 (S.D. Tex. 2019). In
this context, to “remand” means to return the rule to the agencies to reconsider possible errors or defects in their action.
A court order that remands a rule may or may not render the rule unenforceable during any further proceedings.
23 For example, EPA, “EPA, U.S. Army Repeal 2015 Rule Defining ‘Waters of the United States’ Ending Regulatory
Patchwork,” Sept. 12, 2019, https://www.epa.gov/newsreleases/epa-us-army-repeal-2015-rule-defining-waters-united-
states-ending-regulatory-patchwork.
24 Army Corps of Engineers and EPA, “Definition of ‘Waters of the United States’—Recodification of Pre-Existing
Rules,” 84 Federal Register 56626, Oct. 22, 2019.
25 Army Corps of Engineers and EPA, “The Navigable Waters Protection Rule: Definition of ‘Waters of the United
States,’” 85 Federal Register 22250, Apr. 21, 2020.
26 Executive Order 13990, “Protecting Public Health and the Environment and Restoring Science to Tackle the Climate
Crisis,” 86 Federal Register 7037-7043, Jan. 20, 2021.
27 EPA, “EPA, Army Announce Intent to Revise Definition of WOTUS,” press release, June 9, 2021, at
https://www.epa.gov/newsreleases/epa-army-announce-intent-revise-definition-wotus (hereinafter “June 2021 Press
Release”); see also, e.g., Motion for Remand Without Vacatur, Conservation Law Found. v. EPA, No. 1:20-cv-10820
(D. Mass. June 6, 2021), ECF No. 112.
28 Pascua Yaqui Tribe v. EPA, 557 F. Supp. 3d 949 (D. Ariz. 2021). One other court subsequently vacated the
Navigable Waters Protection Rule, adopting similar reasoning to the Pascua Yaqui court. Memorandum Opinion and
Order, Navajo Nation v. Regan, No. 2:20-cv-00602 (D.N.M. Sept. 27, 2021), ECF No. 43. In this context, to “vacate”
the rule means to declare it invalid, as if the rule had never been in effect.
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flaws.29 In response to the order, the Corps and EPA announced that they had halted
implementation of the Navigable Waters Protection Rule and would interpret WOTUS consistent
with the pre-2015 regulatory regime until further notice.30
How Does the 2023 WOTUS Rule Define WOTUS?
On January 18, 2023, the Corps and EPA, under the Biden Administration, published a new rule
(the 2023 WOTUS Rule) redefining WOTUS in the agencies’ regulations.31 The rule went into
effect on March 20, 2023, but was immediately challenged. The rule is currently in effect in 23
states, while the pre-2015 regulations are in effect in the remaining states and as applied to a
group of industry associations that are participating in the pending litigation (see “Which Rule Is
in Effect Now?”)
The Corps and EPA asserted that their intent in promulgating the 2023 WOTUS Rule was to
redefine WOTUS in a durable regulation, updating the pre-2015 rules to reflect consideration of
Supreme Court decisions, science, and the agencies’ experience and technical expertise.32 Overall,
the definition of WOTUS in the 2023 WOTUS Rule is narrower in scope than the Clean Water
Rule and broader than the Navigable Waters Protection Rule.
The 2023 WOTUS Rule is divided into three parts: jurisdictional waters (WOTUS), exclusions,
and definitions. These parts are summarized below, and compared to the pre-2015 rules and
guidance.
Jurisdictional Waters (WOTUS)
The 2023 WOTUS Rule includes seven WOTUS categories (Table 1).
Table 1. Jurisdictional Waters (WOTUS) Under the 2023 WOTUS Rule
Regulatory
Category of
Text
WOTUS
Description
Paragraph
Traditional Navigable Waters, such as large rivers and lakes, which are, were, or could be used
(a)(1)
Waters
in interstate or foreign commerce, including waters affected by tides.
Territorial Seas
The territorial seas are the belt of the seas extending three miles out
(a)(1)
from the coast.
Interstate Waters
Waters, such as rivers, lakes, streams, or wetlands that flow across or
(a)(1)
form part of state boundaries.
Impoundments of
Impounded waters created in or from jurisdictional waters, whether
(a)(2)
Jurisdictional Waters
natural (e.g., beaver ponds) or artificial (e.g., reservoirs).

29 Pascua Yaqui, 557 F. Supp. 3d at 955.
30 See EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,” Dec. 30, 2022,
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
31 2023 WOTUS Rule.
32 2023 WOTUS Rule, p. 3019; and 2022 WOTUS Fact Sheet.
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Regulatory
Category of
Text
WOTUS
Description
Paragraph
Tributaries
Waters such as branches of creeks, streams, rivers, lakes, ponds, ditches,
(a)(3)
and impoundments that flow into traditional navigable waters, the
territorial seas, interstate waters, or impoundments of jurisdictional
waters. Tributaries are WOTUS if they meet either the relatively
permanent standard or the significant nexus standard as described further
in the 2023 WOTUS Rule.
Adjacent Wetlands
Wetlands that are (1) adjacent to a traditional navigable water, the
(a)(4)
territorial seas, or an interstate water; (2) adjacent and with a continuous
surface connection to either relatively permanent jurisdictional
impoundments or jurisdictional tributaries that meet the relatively
permanent standard; or (3) wetlands adjacent to jurisdictional
impoundments or jurisdictional tributaries when the wetlands meet the
significant nexus standard.
Wetlands, defined in the rule, generally include swamps, marshes, bogs,
and similar areas. Adjacent is defined in the rule to mean “bordering,
contiguous, or neighboring.” The definition also specifies that wetlands
separated from other WOTUS by man-made dikes or barriers, natural
river berms, beach dunes, and the like are “adjacent wetlands.”
“Additional
Lakes, ponds, streams, or wetlands that do not fall under one of the other
(a)(5)
waters”—intrastate
WOTUS categories. Such waters are jurisdictional if they meet either the
lakes and ponds,
relatively permanent or significant nexus standard.
streams, or wetlands
Sources: CRS analysis; 2023 WOTUS Rule; 2022 WOTUS Fact Sheet.
Traditional Navigable Waters, the Territorial Seas and Interstate Waters
(Paragraph (a)(1) Waters)
The 2023 WOTUS Rule retains three categories without changes to the text or substance from
pre-2015 regulations.33 These include the traditional navigable waters, the territorial seas, and
interstate waters. However, the agencies restructured the rule to streamline the regulatory text,
and combined these three still-separate categories under one paragraph (i.e., (a)(1) waters)
because, as the agencies explain in the rule’s preamble, the jurisdictional status of other categories
of waters relies on their connection to waters from one of these three categories.34
Impoundments of Jurisdictional Waters
The 2023 WOTUS Rule also retains the impoundments of jurisdictional waters category with one
change from the pre-2015 regulations.35 The pre-2015 regulations included impoundments of any
WOTUS, but the 2023 WOTUS Rule would exclude impoundments of waters determined to be
jurisdictional under paragraph (a)(5), which the Corps and EPA in their fact sheet refer to as
“additional waters.”36 These “additional waters” are a subset of what was previously referred to as
the “other waters” category. (See further discussion on “additional waters” below.)

33 2023 WOTUS Rule, p. 3068.
34 Ibid.
35 2023 WOTUS Rule, pp. 3075-3076.
36 2023 WOTUS Rule, p. 3066; and 2022 WOTUS Fact Sheet, p. 2. Note that impoundments of (a)(5) waters may still
be determined to be jurisdictional if they meet the requirements of another category of WOTUS.
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Waters of the United States (WOTUS): Frequently Asked Questions

Tributaries, Adjacent Wetlands, and “Additional Waters”
The remaining three categories—tributaries, adjacent wetlands, and “additional waters”—reflect
the definition of WOTUS from pre-2015 regulations, but include changes that the agencies assert
reflect Supreme Court precedent, science, and their technical expertise.37 For example, the 2023
WOTUS Rule clarifies that the waters in these three categories may meet either the relatively
permanent standard or the significant nexus standard for purposes of determining jurisdiction.38
The Corps and EPA explained that this aspect of the 2023 WOTUS Rule is not an application or
interpretation of the multiple opinions in Rapanos.39 Instead, these standards are contained in the
2023 WOTUS Rule text and are informed by, but separate from, the two tests identified by the
Supreme Court. In addition, the agencies made certain changes to each of the categories that
constrain which waters are jurisdictional, in comparison to the pre-2015 regulations.
• Tributaries: A tributary is considered a WOTUS under the 2023 WOTUS Rule if
it is a tributary of a traditional navigable water, the territorial seas, an interstate
water, or an impoundment of a jurisdictional water and also meets either the
relatively permanent or significant nexus standard.40

As compared to the pre-2015 regulations, the 2023 WOTUS Rule adds the
territorial seas to the list of waters to which a water may be a tributary. The
agencies note that, in practice, this is not a significant change as most tributaries
will reach a traditional navigable water before they reach the territorial seas.41

The 2023 WOTUS Rule also deletes the “additional waters” category from the
list of waters to which a water may be a tributary.42 The pre-2015 regulations
included the comparable “other waters” category on the list, and the “other
waters” category itself was broader, as discussed below.43

Similar to the pre-2015 regulations, the 2023 WOTUS rule does not contain a
definition of “tributary.”44 In addition, consistent with the pre-2015 regulations,
the 2023 WOTUS rule does not include or exclude tributaries as WOTUS based
on their flow regime (i.e., meaning whether they flow year-round, seasonally, or
only in response to precipitation events).45

37 2023 WOTUS Rule, pp. 3005-3006; and 2022 WOTUS Fact Sheet.
38 Ibid.
39 2023 WOTUS Rule, p. 3022.
40 2023 WOTUS Rule, p. 3142.
41 2023 WOTUS Rule, pp. 3079-3080.
42 Ibid.
43 1986 Corps Rule, p. 41250.
44 2023 WOTUS Rule, pp. 3080-3081. Both the Clean Water Rule and the Navigable Waters Protection Rule included
a definition of “tributary.” In the preamble to the 2023 WOTUS Rule, the agencies concluded that a definition was not
required because the agencies have decades of experience implementing the 1986 regulations, which also did not
include a definition. Further, the agencies assert that they “articulate and explain the agencies’ well-established
interpretation and practices for identifying tributaries” in the preamble.
45 2023 WOTUS Rule, pp. 3080-3081. The rule’s preamble clarifies that “a tributary for purposes of this rule includes
rivers, streams, lakes, ponds, and impoundments, regardless of their flow regime, that flow directly or indirectly
through another water or waters to a traditional navigable water, the territorial seas, or an interstate water.” Note that
the Navigable Waters Protection Rule’s definition required that a tributary be perennial (i.e., flow year-round) or
intermittent (i.e., flow continuously only during certain times of the year, such as seasonally) and excluded ephemeral
(continued...)
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• Adjacent wetlands: Under the 2023 WOTUS Rule, adjacent wetlands are
considered WOTUS if (1) they are adjacent to traditional navigable waters,
interstate waters, or the territorial seas; (2) they are adjacent to and with a
continuous surface connection to jurisdictional impoundments or tributaries that
meet the relatively permanent standard; or (3) they are adjacent to jurisdictional
impoundments or tributaries and meet the significant nexus standard.46 The pre-
2015 regulations more broadly included wetlands adjacent to waters in any of the
WOTUS categories, other than wetlands themselves.47 (Note that the 2008
Rapanos Guidance provided additional specifics as to which wetlands were
WOTUS, as discussed in Table 2.) Thus, in comparison to the pre-2015
regulations, the 2023 WOTUS Rule requires an additional demonstration for
wetlands adjacent to waters that are not (a)(1) waters, that the wetlands have a
continuous surface connection to a relatively permanent water or a significant
nexus to an (a)(1) water.48
• “Additional waters”: Under the 2023 WOTUS Rule, intrastate lakes, ponds,
streams, or wetlands not identified in the other WOTUS categories similarly must
meet either the relatively permanent standard or the significant nexus standard.49
The agencies clarify that this category is substantially narrower than the non-
exclusive list of “other waters” that was included under the pre-2015
regulations.50 The agencies also replaced the broad Commerce Clause basis for
jurisdiction from the pre-2015 regulations with the relatively permanent and
significant nexus standards.51
Exclusions
The 2023 WOTUS Rule includes eight exclusions from the definition of WOTUS.52 Some are
long-standing exclusions for prior converted cropland and waste treatment systems that were
included in pre-2015 regulatory text. Others exclude features that were generally considered non-
jurisdictional under the pre-2015 regime, but were listed as such in preamble language and
guidance rather than the regulatory text.53 Furthermore, these eight features were excluded in each
of the subsequent rules defining WOTUS (the Clean Water Rule and the Navigable Waters
Protection Rule), although the scope of some of these exclusions differed between rules.54 The
exclusions include
• Waste treatment systems, including treatment ponds or lagoons designed to
meet the requirements of the CWA;

streams (i.e., those that flow only in response to precipitation events). The Clean Water Rule’s definition provided that
a tributary could be perennial, intermittent, or ephemeral as long as other criteria in the definition were met.
46 2023 WOTUS Rule, p. 3142.
47 1986 Corps Rule, p. 41250.
48 2023 WOTUS Rule, pp. 3090, 3142.
49 2023 WOTUS Rule, p. 3142.
50 2023 WOTUS Rule, p. 3097.
51 Ibid. The pre-2015 regulatory framework included as jurisdictional waters “the use, degradation, or destruction of
which could affect interstate or foreign commerce.” 1986 Corps Rule, p. 41250.
52 2023 WOTUS Rule, pp. 3066-3067 and 3142-3143.
53 Ibid.
54 2023 WOTUS Rule, p. 3103. See also 2015 Clean Water Rule, p. 37118; 2020 Navigable Waters Protection Rule, p.
22340. Note these exclusions were either explicitly listed, or were excluded under a broader exclusion category.
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• Prior converted cropland (see discussion below);
• Ditches (including roadside ditches), excavated wholly in and draining only dry
land and that do not carry a relatively permanent flow of water;
• Artificially irrigated areas that would revert to dry land if the irrigation ceased;
• Artificial lakes or ponds created by excavating or diking dry land to collect and
retain water and which are used exclusively for such purposes as stock watering,
irrigation, settling basins, or rice growing;
• Artificial reflecting pools or swimming pools or other small ornamental
bodies of water created by excavating or diking dry land to retain water for
primarily aesthetic reasons;
• Waterfilled depressions created in dry land incidental to construction activity
and pits excavated in dry land for the purpose of obtaining fill, sand, or gravel
unless and until the construction is abandoned and the resulting body of water
meets the definition of WOTUS; and
• Swales and erosional features (e.g., gullies, small washes) characterized by low
volume, infrequent, or short duration flow.
Regarding prior converted cropland, in the 2023 WOTUS Rule, the agencies repromulgated the
pre-2015 regulatory exclusion, but also made certain changes to the regulatory text in what the
agencies described as an effort to improve clarity and consistency with the implementation by the
U.S. Department of Agriculture (USDA) of the Food Security Act of 1985, as amended.55 The
Food Security Act includes a provision (the “Swampbuster” exception) which requires USDA to
make determinations about whether wetland areas qualify as prior converted cropland.56 The new
regulatory text in the 2023 WOTUS Rule specifies that prior converted cropland designated by
USDA is excluded. The regulatory text also clarifies that the exclusion would cease upon a
change of use, meaning the area is no longer available for the production of agricultural
commodities.57 This change aligns the WOTUS regulatory exclusion with the Swampbuster
exception for prior converted cropland.58
Definitions
The 2023 WOTUS Rule includes six definitions. Five of the six definitions are unchanged from
the pre-2015 regulations, including the definitions for “wetlands,” “adjacent,” “high tide line,”
“ordinary high water mark,” and “tidal water.”59
The 2023 WOTUS Rule newly defines the term “significantly affect,” for purposes of
determining whether a water meets the significant nexus standard, to mean “a material influence
on the chemical, physical, or biological integrity” of an (a)(1) water (i.e., traditional navigable
waters, the territorial seas, or interstate waters).60 The definition also identifies functions to be

55 2023 WOTUS Rule, pp. 3105-3107.
56 See CRS In Focus IF11136, Prior Converted Cropland Under the Clean Water Act, by Laura Gatz and Megan
Stubbs for more information.
57 2023 WOTUS Rule, p. 3142.
58 2023 WOTUS Rule, pp. 3105-3107.
59 2023 WOTUS Rule, pp. 3067, 3143.
60 Ibid.
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assessed and factors to be considered in determining whether waters, either alone or in
combination with similarly situated waters in the region, significantly affect an (a)(1) water.61
Which Rule Is in Effect Now?
The 2023 WOTUS Rule went into effect on March 20, 2023. Litigation has changed which rule is
in effect in some states, however. Two federal district courts have issued preliminary injunctions,
and one court of appeals has issued an injunction pending appeal, that collectively bar
implementation of the 2023 WOTUS Rule in 27 states.62 The injunction pending appeal also
applies to several industry associations that are plaintiffs in that lawsuit, as well as to their
members.63 In those states and as to those associations and their members, the Corps and EPA
stated that they would interpret WOTUS “consistent with the pre-2015 regulatory regime.”64

61 Ibid. Functions, as listed in the rule, include contribution of flow; trapping, transformation, filtering, and transport of
materials (including nutrients, sediment, and other pollutants); retention and attenuation of floodwaters and runoff;
modulation of temperature in paragraph (a)(1) waters; or provision of habitat and food resources for aquatic species in
paragraph (a)(1) waters. Factors, as listed in the rule, include the distance from a paragraph (a)(1) water; hydrologic
factors such as the frequency, duration, magnitude, timing, and rate of hydrologic connections, including shallow
subsurface flow; the size, density, or number of waters that have been determined to be similarly situated; landscape
position and geomorphology; and climatological variables such as temperature, rainfall, and snowpack.
62 Memorandum Opinion and Order Granting Preliminary Injunction, Texas v. EPA, No. 3:23-cv-17 (S.D. Tex. Mar.
19, 2023), ECF No. 60; Order Granting Plaintiffs’ Motion for Preliminary Injunction, West Virginia v. EPA, No. 3:23-
cv-00032 (D.N.D. Apr. 12, 2023), ECF No. 131; Order, Kentucky v. EPA, No. 23-5343 (6th Cir. May 10, 2023), ECF
No. 24.
63 Order, Kentucky v. EPA, No. 23:5343 (6th Cir. May 10, 2023), ECF No. 24.
64 EPA, Definition of “Waters of the United States”: Rule Status and Litigation Update (last updated May 30, 2023),
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
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Figure 1. Status of 2023 WOTUS Rule as of June 22, 2023

Source: CRS.
Note: The Corps and EPA are also interpreting WOTUS consistent with the pre-2015 framework for the
industry association plaintiffs in Kentucky v. EPA, No. 23-5343 (E.D. Ky.), and for their members.
The Supreme Court’s recent decision in Sackett v. EPA does not directly affect the status of the
2023 WOTUS Rule.65 The majority’s opinion nevertheless rejects jurisdictional interpretations
that are reflected in the 2023 WOTUS Rule, so the continued viability of the rule is uncertain.
The decision also raises uncertainty regarding prior regulatory frameworks, which all extended
jurisdiction to more wetlands than are covered under the Sackett majority’s interpretation.
Following the Court’s decision, the Corps and EPA stated that they “will interpret the phrase
‘waters of the United States’ consistent with the Supreme Court’s decision in Sackett,” but the
agencies have not provided any information regarding that interpretation.66
A change in regulatory regime will not result in the retroactive application of a new rule to all
potentially covered waters. In particular, the transition to the 2023 WOTUS Rule does not
necessarily invalidate approved jurisdictional determinations (AJDs), which the Corps issues to
identify whether a particular parcel of land contains WOTUS, and which may be used in the
CWA permitting process.67 Approved jurisdictional determinations completed when the
Navigable Waters Protection Rule or pre-2015 regulatory framework were in effect will not be
reopened before their expiration date unless they satisfy specific criteria for revision.68

65 See infra, “How Does Sackett v. EPA Affect the Scope of CWA Jurisdiction?”
66 EPA, Definition of “Waters of the United States”: Rule Status and Litigation Update (last updated May 30, 2023),
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
67 See 33 C.F.R. § 331.2.
68 See EPA, “Current Implementation of Waters of the United States,” Jan. 18, 2023, https://www.epa.gov/wotus/
current-implementation-waters-united-states; and U.S. Army Corps of Engineers, Regulatory Guidance Letter No. 05-
02 (June 14, 2005).
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Additionally, enforcement actions for violations of the CWA are typically based on the statutory
and regulatory framework that was in effect at the time the violations occurred, even if the rule
has since changed.
Has the 2023 WOTUS Rule Been Challenged
in Court?
Five pending lawsuits challenge the 2023 WOTUS Rule.69 While no court has issued a ruling on
the merits, preliminary orders have limited the implementation of the 2023 WOTUS Rule for
some states and plaintiffs.
The first two lawsuits were filed on January 18, 2023, and have been consolidated in the U.S.
District Court for the Southern District of Texas.70 In the first suit, the State of Texas argues that
the rule unlawfully expands the Corps and EPA’s jurisdiction beyond the bounds of the CWA,
violates the major questions doctrine71 because the CWA does not authorize the agencies to
determine the scope of their own jurisdiction, intrudes upon state sovereignty, and violates due
process by failing to provide adequate notice of what conduct is prohibited under the statute.72 In
the second suit, a coalition of agricultural and industry groups argues that the rule is unsupported
by law and scientific and economic evidence; violates the Commerce Clause, the Due Process
Clause of the Fifth Amendment, the major questions doctrine, and the nondelegation doctrine;73
exceeds the Corps’ and EPA’s statutory authority; and unlawfully fails to include a regulatory
flexibility analysis.74 An environmental group has intervened in the lawsuits in support of the
Corps and EPA.75
Third, a group of 24 states has challenged the 2023 WOTUS Rule in the U.S. District Court for
the District of North Dakota.76 In addition to arguments similar to those made by the Texas
plaintiffs, the state plaintiffs allege that the rule violates the APA because the final rule is not a
“logical outgrowth” of the rule the agencies proposed in December 2021 and that the rule violates
the Tenth Amendment by asserting federal jurisdiction over intrastate waters and lands that are
ordinarily regulated by the states.77 The agricultural and industry groups challenging the rule in

69 Prior rules defining WOTUS were the subject of numerous lawsuits filed by industry groups, environmental groups,
and states. In 2018, the Supreme Court held that challenges to a rule defining WOTUS are typically governed by the
APA and must be reviewed first in federal district court. Nat’l Ass’n of Mfrs. v. Dept’ of Def., 138 S. Ct. 617 (2018).
That holding limited the degree to which the agencies, under rules of court procedure, can seek a single nationwide
decision about the validity of the 2023 WOTUS Rule.
70 Order, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 13, 2023), ECF No. 27.
71 Under the major questions doctrine, an agency must provide clear congressional authorization in certain cases when
it seeks to decide an issue of major national significance. For additional background on the major questions doctrine,
see CRS In Focus IF12077, The Major Questions Doctrine, by Kate R. Bowers.
72 Complaint, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Jan. 18, 2023), ECF No. 1.
73 The nondelegation doctrine is the separation-of-powers principle that limits Congress’s ability to cede its legislative
power to other branches of government or nongovernmental entities. For further discussion of the nondelegation
doctrine, see Nondelegation Doctrine, Constitution Annotated, https://constitution.congress.gov/browse/article-1/?
anchor=I_S1_5#I_S1_5.
74 First Amended Complaint, Am. Farm Bureau Fed’n v. EPA, No. 3:23-cv-00020 (S.D. Tex. Feb. 2, 2023), ECF No. 1.
75 Bayou City Waterkeeper Motion to Intervene, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 9, 2023), ECF No.
20; Bayou City Waterkeeper Motion to Intervene, Am. Farm Bureau Fed’n v. EPA, No. 3:23-cv-00020 (S.D. Tex. Feb.
9, 2023), ECF No. 16; Order, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 14, 2023), ECF No. 30.
76 Complaint, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Feb. 16, 2023), ECF No. 1.
77 Id.
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Texas have also intervened in the North Dakota litigation in support of the state plaintiffs,
although the Corps and EPA have appealed the district court’s order granting the groups’ motion
to intervene.78
Fourth, the Commonwealth of Kentucky has challenged the 2023 WOTUS Rule in the U.S.
District Court for the Eastern District of Kentucky, raising similar allegations to those made by
Texas and the other state plaintiffs.79 A fifth suit, filed in the Eastern District of Kentucky by a
coalition of industry associations, was consolidated with the Commonwealth of Kentucky’s
lawsuit.80
The plaintiffs in each lawsuit filed motions asking the courts to bar implementation of the 2023
WOTUS Rule while the litigation is pending.81 Two district courts have granted the motions and
issued preliminary injunctions: The Texas district court granted Texas and Idaho’s motion, and the
North Dakota district court granted the state plaintiffs’ motion.82
In granting Texas and Idaho’s motion, the Texas district court noted that the 2023 WOTUS Rule’s
extended the significant nexus standard beyond the breadth intended by Justice Kennedy in
Rapanos and identified potential constitutional problems with the rule’s coverage of all interstate
waters.83 The court denied the Texas industry plaintiffs’ request for a nationwide injunction,
however, holding that the industry associations had not demonstrated that they were entitled to
injunctive relief beyond what was granted to the states.84 In granting the state plaintiffs’ motion
for preliminary injunction, the North Dakota court agreed with the Texas court’s analysis,
expressed concerns about the 2023 Rule’s treatment of tributaries and impoundments, and
indicated that the agencies’ interpretation was likely in excess of their statutory authority,
arbitrary and capricious, and in conflict with various constitutional limitations.85 The North
Dakota district court has not yet ruled on the industry plaintiffs’ motion. The Corps and EPA have
appealed both the Texas and North Dakota preliminary injunctions.86
The litigation in Kentucky has proceeded differently. In March 2023, the Kentucky district court
denied both preliminary injunctions without prejudice and dismissed Kentucky and the industry
plaintiffs’ claims.87 While the court noted that the plaintiffs’ allegations “may very well present a
federal cause of action” in the future, their alleged injuries were too speculative and generalized
to support their claims of standing and ripeness.88 Both Kentucky and the industry plaintiffs

78 Order and Federal Defendants’ Appeal from the Magistrate Judge’s Order Granting Industry’s Motion to Intervene,
West Virginia v. EPA (D.N.D. March 22, 2023 and Apr. 5, 2023), ECF Nos. 110 and 129.
79 Complaint, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 22, 2023), ECF No. 1.
80 Complaint, Kentucky Chamber of Commerce v. EPA, No. 3:23-cv-00008 (E.D. Ky. Feb. 22, 2023); Order, Kentucky
v. EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 28, 2023), ECF No. 16.
81 Motion for Preliminary Injunction, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 7, 2023), ECF No. 13; Motion
for Preliminary Injunction, Am. Farm Bureau Fed’n v. EPA, No. 3:23-cv-00020 (S.D. Tex. Feb. 7, 2023), ECF No. 15;
Plaintiff States’ Motion for Preliminary Injunction, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Feb. 21, 2023),
ECF No. 44; Motions for Preliminary Injunction, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 23 and Feb. 28,
2023), ECF Nos. 10 and 17.
82 Memorandum Opinion and Order Granting Preliminary Injunction, Texas v. EPA, No. 3:23-cv-00017 (E.D. Tex.
Mar. 19, 2023), ECF No. 60; Order Granting Plaintiffs’ Motion for Preliminary Injunction, West Virginia v. EPA
(D.N.D. Apr. 12, 2023), ECF No. 131.
83 Memorandum Opinion and Order Granting Preliminary Injunction at 19-26, Texas v. EPA.
84 Id. at 34.
85 Order Granting Plaintiffs’ Motion for Preliminary Injunction at 17-29, West Virginia v. EPA.
86 Texas v. EPA, No. 23-40306 (5th Cir. 2023), West Virginia v. EPA, No. 23-2411 (8th Cir. 2023).
87 Opinion and Order, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Mar. 31, 2023), ECF No. 51.
88 Id. at 1.
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appealed those rulings to the U.S. Court of Appeals for the Sixth Circuit and sought a stay of the
district court’s decision pending appeal. In May 2023, the Sixth Circuit granted an injunction
pending appeal, holding that the plaintiffs’ general allegations of injury were likely sufficient at
this stage of litigation.89
As a result of the preliminary injunctions and injunction pending appeal, the pre-2015 framework
is in effect in 27 states and as applied to the Kentucky industry plaintiffs and their members.
Further proceedings in any of the pending lawsuits—or any newly filed lawsuits—could increase
or decrease the number of states in which the 2023 WOTUS Rule is in effect.90 It is also likely
that further proceedings within the context of the pending lawsuits will address the effect of the
Supreme Court’s ruling in Sackett on the continued viability of the 2023 WOTUS Rule.
How Does Sackett v. EPA Affect the Scope of CWA
Jurisdiction?
On May 25, 2023, the Supreme Court decided Sackett v. EPA, a case with significant implications
for the scope of federal jurisdiction under the CWA.91 In Sackett, landowners in Idaho challenged
a compliance order and asked the Court to revisit Rapanos and adopt Justice Scalia’s plurality test
for determining whether certain adjacent wetlands are WOTUS. Applying the significant nexus
test articulated by Justice Kennedy in Rapanos, the U.S. Court of Appeals for the Ninth Circuit
upheld EPA’s conclusion that the Sacketts’ property contained WOTUS that were subject to
federal jurisdiction under the CWA and relevant regulations.92
On review, the Supreme Court unanimously reversed the Ninth Circuit. Although all nine Justices
agreed that the lower court applied the wrong standard for identifying WOTUS, the Court was
split 5-4 on the appropriate test. In an opinion authored by Justice Alito, the majority formally
adopted the approach taken by the Rapanos plurality. The majority held that “waters” under the
CWA are limited to “relatively permanent, standing or continuously flowing bodies of water
forming geographic[al] features that are described in ordinary parlance as streams, oceans, rivers,
and lakes.”93 The majority also held that the CWA covers only wetlands that qualify as WOTUS
“in their own right.”94 This limited covered wetlands to those that are “indistinguishably part of a
body of water that itself constitutes ‘waters’ under the CWA.”95 Quoting the Rapanos plurality,
the majority concluded that WOTUS includes “only those wetlands that are as a practical matter
indistinguishable from waters of the United States, such that it is difficult to determine where the
water ends and the wetland begins. That occurs when wetlands have a continuous surface
connection to bodies that are waters of the United States in their own right, so that there is no
clear demarcation between waters and wetlands.”96 Accordingly, the majority ruled that CWA

89 Order, Kentucky v. EPA, No. 23-5343 (6th Cir. May 10, 2023), ECF No. 24.
90 Consistent with the statute of limitations for APA claims, potential litigants would generally be required to file suit
within six years after their claims accrue. 28 U.S.C. § 2401(a). While additional lawsuits are thus possible, early
lawsuits are the most likely to be closely watched, as they present the courts’ first opportunities to issue rulings that
may be binding in later cases.
91 Sackett v. EPA, No. 21-454 (U.S. May 25, 2023). For a more in-depth discussion of Sackett, see CRS Legal Sidebar
LSB10981, Supreme Court Narrows Federal Jurisdiction Under Clean Water Act, by Kate R. Bowers.
92 Sackett v. EPA, 8 F.4th 1075 (9th Cir. 2021).
93 Sackett v. EPA, No. 21-454, slip op. at 14 (U.S. May 25, 2023).
94 Id. at 19.
95 Id. at 22.
96 Id. at 21.
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jurisdiction excludes wetlands that are neighboring to but separate from traditional navigable
waters.97
In addition to reaffirming the Rapanos plurality’s standard, the majority also rejected the
significant nexus test.98 The majority noted that Congress must “enact exceedingly clear language
if it wishes to significantly alter the balance between federal and state power and the power of the
Government over private property” and further reasoned that the significant nexus test “gives rise
to serious vagueness concerns in light of the CWA’s criminal penalties.”99 According to the
majority, the significant nexus test thus amounted to a “freewheeling inquiry” that “provides little
notice to landowners of their obligations under the CWA.”100
The Court’s ruling narrows the scope of jurisdiction under the CWA as compared to its long-
standing regulatory implementation and narrows the interpretation adopted by lower courts post-
Rapanos. While the precise extent of the change will depend on how the Corps and EPA
implement various aspects of the decision, the majority’s exclusion of wetlands that are separated
from covered waters by natural or artificial barriers means that fewer wetlands will be covered
than under any regulatory framework developed by the Corps or EPA since the 1970s.101
Additionally, the majority’s definition of waters appears to exclude ephemeral waters, thus
narrowing the scope of waters as compared to the 2023 WOTUS Rule, the 2015 Clean Water
Rule, and the pre-2015 regulations and guidance.
Neither the 2023 Rule nor any prior regulation was presented to the Supreme Court for review in
Sackett, so the Court’s decision does not automatically affect the status of the 2023 WOTUS
Rule. The majority opinion nevertheless rejects jurisdictional interpretations that are reflected in
the 2023 WOTUS Rule, so the continued viability of the rule is uncertain. The viability of the
pre-2015 framework—to which the Corps and EPA have reverted in some parts of the country
due to court orders temporarily barring implementation of the 2023 WOTUS Rule—is also
uncertain, as the pre-2015 operative definition of WOTUS included more wetlands than are
covered under the Sackett majority’s interpretation. Following the Court’s decision, the Corps and
EPA issued a statement that they will “interpret the phrase ‘waters of the United States’ consistent
with the Supreme Court’s decision in Sackett” and “continue to review the decision to determine
next steps.”102 While the nature of those next steps remains to be seen, delays in CWA permitting
and other CWA actions are possible. Following Rapanos, the Corps urged its district offices to
delay issuing AJDs for areas beyond the limits of the traditional navigable waters until the
agencies issued final guidance interpreting WOTUS in light of the Supreme Court’s decision.103
Following Sackett, at least one Corps district office has delayed issuing AJDs until further
notice.104
The Supreme Court’s ruling could also affect regulation of waters at the state level. The CWA
expressly reserves to states the right to issue more stringent regulations, and states may choose to

97 Id. at 25.
98 Id. at 22.
99 Id. at 24.
100 Id. at 25.
101 Sackett v. EPA, No. 21-454, slip op. at 6 (U.S. May 25, 2023) (Kavanaugh, J., concurring in the judgment).
102 EPA, Definition of “Waters of the United States”: Rule Status and Litigation Update (last updated May 30, 2023),
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
103 U.S. Army Corps of Engineers, Interim Guidance on the Rapanos and Carabell Supreme Court Decision (July 5,
2006).
104 U.S. Army Corps of Engineers, Chicago District Website, Jurisdictional Determinations,
https://www.lrc.usace.army.mil/Missions/Regulatory/Jurisdictional-Determinations/ (last visited June 15, 2023).
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cover more waters in their own programs.105 Some states regulate waters within their borders
beyond the scope of federal jurisdiction and have indicated that they plan to continue or expand
such protections following Sackett.106 Other states have enacted laws barring environmental state
agencies from promulgating regulations beyond what is federally required.107 A narrowed
definition of WOTUS at the federal level could thus result in greater state-level divergence in the
scope of covered waters.
How Have Adjacent Wetlands Been Addressed in
Prior WOTUS Regulations?
The Corps and EPA have long included adjacent wetlands as their own category in the regulations
they have promulgated to define WOTUS. While some rules included a more expansive
definition and others narrower definitions of adjacent wetlands, all of the rules have recognized
adjacent wetlands as WOTUS. These rules have provided that wetlands separated from other
WOTUS by “man-made dikes or barriers, natural river berms, beach dunes and the like” are
adjacent wetlands.108 The scope of adjacent wetlands in the Sackett decision, as previously
discussed, diverges from long-standing regulations and practice by excluding wetlands separated
from WOTUS. Table 2 summaries the scope of adjacent wetlands in the pre-2015 regulations, the
2015 Clean Water Rule, the 2020 Navigable Waters Protection Rule, the 2023 WOTUS Rule, and
the Sackett v. EPA decision.

105 33 U.S.C. § 1370.
106 E.g., California State Water Resources Control Board, press release, State Water Board Statement: U.S. Supreme
Court decision decreases federal wetlands protection (May 25, 2023),
https://waterboards.ca.gov/press_room/press_releases/2023.html.
107 See Corps and EPA, Resource and Programmatic Assessment for the Navigable Waters Protection Rule: Definition
of "Waters of the United States," January 23, 2020, p. 45-46, https://www.epa.gov/sites/production/files/2020-
01/documents/rpa_-_nwpr_.pdf. Environmental Law Institute, State Constraints: State-Imposed Limitations on the
Authority of Agencies to Regulate Waters Beyond the Scope of the Federal Clean Water Act, May 2013, p. 1,
https://www.eli.org/sites/default/files/eli-pubs/d23-04.pdf.
108 E.g., Army Corps of Engineers, “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal
Register 41206, 412501, Nov. 13, 1986 (1986 Corps Rule).
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Table 2. Scope of Adjacent Wetlands Under Waters of the United States (WOTUS) Regulations, Guidance, and in the Sackett
v. EPA Decision
Description of the Adjacent Wetlands WOTUS
Definition of Adjacent
Source
Category
Pre-2015
Wetlands adjacent to other jurisdictional waters other •
Bordering, contiguous, or neighboringb
Regulationsa
than waters that are themselves wetlands
•
Wetlands separated from other waters of the United States by man-made dikes or
barriers, natural river berms, beach dunes, and the like are “adjacent wetlands”
2008 Rapanos
•
Wetlands that were adjacent to traditional
Provided that adjacency was established by satisfying one of three criteria:
Guidancec
navigable waters and wetlands that abutted
(1) An unbroken surface or shallow subsurface connection to jurisdictional waters (which
relatively permanent tributaries (described as
may be intermittent);
those that flow year-round or have continuous
flow at least seasonally) of such waters were
(2) Physical separation from jurisdictional waters by man-made dikes or barriers, natural
categorically WOTUS
river berms, beach dunes, or similar features; or
•
(3) Proximity to a jurisdictional water that is reasonably close and supports a science-based

Wetlands adjacent to tributaries that are not
inference of ecological interconnection.
relatively permanent and wetlands adjacent to
but not directly abutting a relatively permanent
tributary were subject to case-by-case significant
nexus analysis to determine jurisdiction
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Description of the Adjacent Wetlands WOTUS
Definition of Adjacent
Source
Category
2015 Clean Water
•
Broadened the category to adjacent waters,
•
Defined adjacent to mean “bordering, contiguous, or neighboring” a traditional
Ruled
including wetlands, ponds, lakes, oxbows,
navigable water, interstate water including an interstate wetland, jurisdictional
impoundments, and similar waters rather than
impoundment, or a jurisdictional tributary.
just adjacent wetlands
•
Included “waters separated by constructed dikes or barriers, natural river berms,
•
Included waters adjacent to traditional navigable
beach dunes, and the like.”
waters, interstate waters including interstate
•
Specified that for the purposes of adjacency, an open water such as a pond or lake
wetlands, jurisdictional impoundments, and
includes any wetlands within or abutting its ordinary high water mark.
jurisdictional tributaries
•
Specified that adjacency was not limited to waters located laterally to a traditional
navigable water, interstate water including an interstate wetland, jurisdictional
impoundment, or a jurisdictional tributary. Instead, adjacent waters were to also
include all waters that connect segments of one of the aforementioned waters or
were located at the head of one of these waters and are bordering, contiguous, or
neighboring.
•
Newly defined neighboring, which set new numeric standards for determining
adjacency (i.e., al waters located within 100 feet of the ordinary high water mark of a
traditional navigable water, interstate water including an interstate wetland,
jurisdictional impoundment, or a jurisdictional tributary; or within the 100-year
floodplain of one of the aforementioned waters and not more than 1,500 feet from
the ordinary high water mark of such water).
2020 Navigable
Adjacent wetlands
Defined adjacent wetlands to mean wetlands that:
Waters Protection
(1) abutted a territorial sea or traditional navigable water, tributary, or a lake, pond, or
Rulee
impoundment of a jurisdictional water;
(2) were inundated by flooding from one of the aforementioned waters in a typical year;
(3) were physically separated from one of the aforementioned waters only by a natural
berm, bank, dune, or similar natural feature; or
(4) were physically separated from one of the aforementioned waters only by an artificial
dike, barrier, or similar artificial structure so long as that structure allowed for a direct
hydrological surface connection to the water in a typical year

Specified that an adjacent wetland is jurisdictional when a road or similar artificial structure
divides the wetland so long as the structure allows for a direct hydrologic surface
connection through or over that structure in a typical year
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link to page 22 link to page 22
Description of the Adjacent Wetlands WOTUS
Definition of Adjacent
Source
Category
2023 WOTUS Rulef
Includes wetlands adjacent to:
•
Bordering, contiguous, or neighboring
(1) traditional navigable waters, interstate waters, or
•
Wetlands separated from other waters of the United States by man-made dikes or
the territorial seas;
barriers, natural river berms, beach dunes, and the like are “adjacent wetlands”
(2) and with a continuous surface connection to
jurisdictional impoundments or tributaries that
are relatively permanent, standing, or
continuously flowing bodies of water; or
(3) jurisdictional impoundments or tributaries when
the wetlands alone or in combination with
similarly situated waters meet the significant
nexus standard
Sackett v. EPAg
Adjacent wetlands that are part of (i.e.,
•
“Only those wetlands that are as a practical matter indistinguishable from waters of
indistinguishable from) waters of the United States
the United States, such that it is difficult to determine where the water ends and the
wetland begins. That occurs when wetlands have a continuous surface connection to
bodies that are waters of the United States in their own right, so that there is no clear
demarcation between waters and wetlands.”
•
Excludes wetlands that are neighboring to but separate from traditional navigable
waters, such as those separated by a barrier.
Source: CRS analysis of WOTUS regulations, guidance, and the Sackett v. EPA decision.
Notes:
a. Army Corps of Engineers, “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal Register 41206, Nov. 13, 1986 (1986 Corps Rule); EPA, “Clean
Water Act Section 404 Program Definitions and Permit Exemptions; Section 404 State Program Regulations,” 53 Federal Register 20764, June 6, 1988 (1988 EPA
Rule).
b. The 1988 EPA Rule did not define adjacent, but the 1986 Corps Rule defined it as described here.
c. Benjamin H. Grumbles, Assistant Administrator for Water, EPA, and John Paul Woodley Jr., Assistant Secretary of the Army (Civil Works), Department of the
Army, Clean Water Act Jurisdiction Following the U.S. Supreme Court’s Decision in Rapanos v. United States & Carabell v. United States, memorandum, Dec. 2, 2008.
d. Army Corps of Engineers and EPA, “Clean Water Rule: Definition of ‘Waters of the United States’; Final Rule,” 80 Federal Register 37054, June 29, 2015.
e. Army Corps of Engineers and EPA, “The Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’” 85 Federal Register 22250, Apr. 21, 2020.
f.
Revised Definition of “Waters of the United States,” 88 Federal Register 3004, Jan. 18, 2023.
g. Sackett v. EPA, No. 21-454 (U.S. May 25, 2023).

CRS-19

Waters of the United States (WOTUS): Frequently Asked Questions

What Options Are Available to Congress Regarding
the Definition of WOTUS?
Considering the numerous court rulings, ongoing legal challenges, and successive
Administrations’ efforts to define the scope of WOTUS, some stakeholders have urged Congress
to more specifically define the term through amendments to the CWA. Others argue that the
Corps and EPA, with their specific knowledge and expertise, are in the best position to determine
the scope of the term. The Sackett v. EPA decision narrows the scope of WOTUS with regard to
how the agencies may interpret the term moving forward but does not preclude Congress from
amending the CWA to define the term with more clarity or specificity.
The scope of WOTUS has continued to be an issue of interest in the 118th Congress. On February
8, 2023, the House Transportation and Infrastructure Committee’s Subcommittee on Water
Resources and Environment held a hearing regarding the 2023 WOTUS Rule.109 Other
committees have held hearings where the topic of WOTUS has been discussed, including a
hearing held by the House Committee on Agriculture.110
Members have introduced legislation related to WOTUS. Members in both chambers introduced
joint resolutions of disapproval of the 2023 WOTUS Rule under the Congressional Review Act
(CRA). In addition, some Members have introduced legislation that would enact the Navigable
Waters Protection Rule’s definition of WOTUS into law, reinstate the Navigable Waters
Protection Rule, or amend the CWA to add a narrower definition of navigable waters. Another
bill would establish an agricultural advisory committee to inform Congress of the impacts of
WOTUS regulations on the agricultural sector.
• H.J.Res. 27 and S.J.Res. 7 are joint resolutions providing for congressional
disapproval of the 2023 WOTUS Rule under the CRA.111 They were sponsored
or cosponsored by 170 Members of the House of Representatives and 49
Senators. In March 2023, both the House and the Senate passed the joint
resolution of disapproval for the 2023 WOTUS Rule, which President Biden
subsequently vetoed.112 The House held a vote to override the veto, which failed
to meet the two-thirds majority needed to pass.
• H.R. 1556, the Define WOTUS Act, and S. 1022, the Define WOTUS Act of
2023, are identical bills that would amend the CWA to change the definition of
navigable waters. The language, as introduced, would narrow the scope of waters
subject to CWA jurisdiction in comparison to any of the WOTUS regulatory

109 U.S. Congress, House Committee on Transportation and Infrastructure, Subcommittee on Water Resources and
Environment, Hearing on Stakeholder Perspectives on Impacts of the Biden Administration’s Waters of the United
States (WOTUS) Rule, 118th Cong., 1st sess., Feb. 8, 2023.
110 U.S. Congress, House Committee on Agriculture, For the Purpose of Receiving Testimony from The Honorable
Michael Regan, Administrator, U.S. Environmental Protection Agency, 118th Cong., 1st sess., Apr. 19, 2023.
111 The CRA allows Congress to overturn certain agency actions in the form of a joint resolution of disapproval.111
Under the CRA, if both houses pass a joint resolution for disapproval, it is sent to the President for signature or veto. If
the President vetoes a resolution, Congress can vote to override the veto with a two-thirds majority in both chambers. If
a joint resolution of disapproval is submitted within the CRA-specified deadline, passed by Congress, and signed by the
President (or if Congress votes to override a presidential veto), the disapproved rule “shall not take effect (or continue)”
and would be deemed not to have had any effect at any time. Furthermore, if a joint resolution of disapproval is
enacted, the CRA provides that a rule may not be issued in “substantially the same form” as the disapproved rule unless
it is specifically authorized by a subsequent law.
112 See, Actions.
Congressional Research Service

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Waters of the United States (WOTUS): Frequently Asked Questions

• regimes (pre-2015, Clean Water Rule, Navigable Waters Protection Rule, and
2023 WOTUS Rule). It would also amend the CWA to make changes to the
Corps process for making jurisdictional determinations.
• S. 782, the FREE American Energy Act, would enact the Navigable Waters
Protection Rule into law.
• S. 879, the Energy Freedom Act, would reinstate the Navigable Waters Protection
Rule and provide that each of its provisions apply until the effective date of a
subsequent final rule. It would also prohibit the Corps and EPA from issuing a
new rule to redefine WOTUS for 15 years from the date of enactment.
• S. 1023, the Farmer-Informed WOTUS Act of 2023, would establish an advisory
committee representative of the United States farming and ranching sectors to
inform Congress of the impact of WOTUS regulations on U.S. agriculture.
• S. 1449, the RESTART Act, would amend the CWA to change the definition of
navigable waters. The language, as introduced, closely aligns with the definition
published in the Navigable Waters Protection Rule.
Moving forward, Congress may oversee the Biden Administration’s implementation of the
Supreme Court’s ruling in Sackett v. EPA or may consider proposing legislation to either provide
a definition of WOTUS or provide more specific instruction to the agencies and regulated parties
as to the interpretation of the CWA. The Supreme Court’s increasing insistence on clear
congressional intent to delegate regulatory authority, and its decreasing reliance on or reference to
more deferential modes of judicial review, suggest that any regulatory actions taken pursuant to
such legislation would be subject to close judicial scrutiny.

Author Information

Kate R. Bowers
Laura Gatz
Legislative Attorney
Specialist in Environmental Policy

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
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under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
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Congressional Research Service
R47408 · VERSION 5 · UPDATED
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