Waters of the United States (WOTUS): Frequently Asked Questions About the Scope of the Clean Water Act
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Waters of the United States (WOTUS):
Frequently Asked Questions About the Scope
of the Clean Water Act
Updated June 23, 2025
Congressional Research Service
https://crsreports.congress.gov
R47408
SUMMARY
Waters of the United States (WOTUS):
Frequently Asked Questions About the Scope
of the Clean Water Act
R47408
June 23, 2025
Kate R. Bowers
Section Research Manager
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 regulations.) The
agencies supplemented these regulations with guidance, which they developed in response to Supreme Court rulings related
to the scope of the federal government’s ability to regulate WOTUS (including the Court’s 2006 ruling in Rapanos v. United
States, 547 U.S. 715). 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
some 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. In January 2023,
the Corps and EPA, under the Biden Administration, also issued a rule redefining WOTUS in the agencies’ regulations (the
2023 WOTUS Rule). 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 2023 WOTUS Rule defined WOTUS more
narrowly than the 2015 Clean Water Rule and more broadly than the 2020 Navigable Waters Protection Rule. As with prior
rulemaking efforts, the 2023 WOTUS Rule prompted strong stakeholder interest with varying views. The 2023 WOTUS Rule
went into effect in March 2023 and was immediately challenged. Three courts stayed implementation of the 2023 WOTUS
Rule in a total of 27 (later reduced to 26) states and as applied to several associations that were participating in the litigation.
In May 2023, the Supreme Court decided Sackett v. EPA, 598 U.S. 651, a case pertaining to the scope of WOTUS. 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. The Court’s ruling significantly
narrowed the scope of WOTUS in comparison not only to the 2023 WOTUS Rule but also to all of the prior regulations the
agencies had promulgated to define WOTUS. Following the Sackett decision, the Corps and EPA issued a final rule to amend
the 2023 WOTUS Rule and conform the definition of WOTUS to the decision in Sackett. This final rule, the 2023
Conforming Rule, was published in the Federal Register on September 8, 2023, and went into effect the same day. As a
result of ongoing litigation, the 2023 WOTUS Rule, as amended by the 2023 Conforming Rule, is in effect in 24 states, the
District of Columbia, and the U.S. territories. In the other 26 states, the Corps and EPA are interpreting WOTUS consistent
with the pre-2015 regulatory regime and the Supreme Court’s decision in Sackett.
On March 12, 2025, the second Trump Administration announced its intent to revise the definition of WOTUS again through
a new rulemaking. The same day, the Corps and EPA issued new guidance to clarify how staff should implement certain
aspects of the Sackett ruling.
In the 119th Congress, Members may seek to oversee the Corps and EPA’s efforts to implement existing regulations or their
efforts to promulgate new regulations. Some in Congress may also consider introducing legislation to define the scope of
WOTUS—to clarify its intent as to the scope of the term—given the challenges each of the past three Administrations has
faced in establishing lasting regulations. Others may support maintaining the current statutory language.
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Waters of the United States (WOTUS): Frequently Asked Questions
Contents
What Actions Have Previous Administrations Taken to Define WOTUS? ..................................... 2
Pre-2015 Rules and Guidance ................................................................................................... 2
2015 Clean Water Rule.............................................................................................................. 4
2020 Navigable Waters Protection Rule ................................................................................... 4
2023 WOTUS Rule and 2023 Conforming Rule ...................................................................... 5
Jurisdictional Waters (WOTUS) ......................................................................................... 6
Exclusions ..........................................................................................................................11
Definitions ........................................................................................................................ 12
Which Rule Is in Effect Now? ....................................................................................................... 12
Have the 2023 WOTUS Rule or 2023 Conforming Rule Been Challenged in Court? ................. 14
How Did Sackett v. EPA Affect the Scope of CWA Jurisdiction? ................................................. 17
What Actions Has the Second Trump Administration Taken to Define WOTUS? ....................... 19
How Have Adjacent Wetlands Been Addressed in Each of the WOTUS Regulations? ................ 20
What Options Are Available to Congress Regarding the Definition of WOTUS? ........................ 25
Figures
Figure 1. Status of the Waters of the United States (WOTUS) Regulatory Regime in
Effect as of June 23, 2025 .......................................................................................................... 13
Tables
Table 1. Description of Jurisdictional Waters (WOTUS) Under the 2023 WOTUS Rule,
as Amended by the 2023 Conforming Rule ................................................................................. 6
Table 2. Scope of Adjacent Wetlands Under Waters of the United States (WOTUS)
Regulations and Guidance and in the Sackett v. EPA Decision .................................................. 21
Contacts
Author Information........................................................................................................................ 28
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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
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.
C
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 Corps and EPA’s efforts to define WOTUS in regulation during both the Obama and first
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
others viewed the first 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, under the Biden Administration, 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 regulations 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 took
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 did not provide
regulatory clarity and was overly broad. Some also argued that the Corps and EPA should have
delayed issuing a rule pending the resolution of Sackett v. EPA, a Supreme Court case that was
pending at the time the rule was issued and that would address 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 (Corps) and Environmental Protection Agency (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); Corps and EPA, “The Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’” 85
Federal Register 22250, April 21, 2020 (hereinafter Navigable Waters Protection Rule).
4 Pascua Yaqui Tribe v. EPA, 557 F. Supp. 3d 949 (D. Ariz. 2021).
5 Corps and EPA, “Revised Definition of ‘Waters of the United States,’” 88 Federal Register 3004, January 18, 2023
(hereinafter 2023 WOTUS Rule). The final rule was published on January 18, 2023. The agencies released a
prepublication version of the rule on December 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, December 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, December 30, 2022.
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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 that
temporarily bar implementation of the rule in 26 states while litigation is pending. Apart from the
pending litigation challenging the 2023 WOTUS Rule, in May 2023, the Supreme Court issued its
ruling in Sackett v. EPA.9 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.10
Following the Court’s ruling, the Corps and EPA published a conforming rule (hereinafter 2023
Conforming Rule) amending key aspects of the 2023 WOTUS Rule to align with the Sackett
decision.11 Currently, the 2023 WOTUS Rule, as amended by the 2023 Conforming Rule, is in
effect in a patchwork of states. In states where courts have temporarily barred the 2023 WOTUS
Rule, the Corps and EPA assert that they are implementing the pre-2015 regulations consistent
with Sackett.12
On March 12, 2025, the second Trump Administration announced its intent to revise the
definition of WOTUS again through new rulemaking.13 The same day, the Corps and EPA also
issued new guidance, to clarify how Corps and EPA staff should implement certain aspects of the
Sackett ruling, and announced they would be holding listening sessions to gather feedback from
stakeholders on how to revise the definition of WOTUS.14
This report addresses frequently asked questions about WOTUS, including actions taken by the
last several Administrations to define WOTUS, the Supreme Court’s ruling in Sackett v. EPA,
implementation of the Sackett decision, 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 (often referred to as the pre-2015 regulations) have been in effect.15 The
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.).
9 598 U.S. 651 (2023).
10 See id. at 679.
11 Corps and EPA, “Revised Definition of ‘Waters of the United States’; Conforming,” 88 Federal Register 61964,
September 8, 2023 (hereinafter 2023 Conforming Rule).
12 EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,”
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
13 EPA, “Administrator Zeldin Announces EPA Will Revise Waters of the United States Rule,” press release,
March 12, 2025, https://www.epa.gov/newsreleases/administrator-zeldin-announces-epa-will-revise-waters-unitedstates-rule.
14 Corps and EPA, Memorandum to the Field Between the U.S. Department of the Army, U.S. Army Corps of Engineers
and the U.S. Environmental Protection Agency Concerning the Proper Implementation of “Continuous Surface
Connection” Under the Definition of “Waters of the United States” Under the Clean Water Act, March 12, 2025,
https://www.epa.gov/system/files/documents/2025-03/2025cscguidance.pdf (hereinafter 2025 Continuous Surface
Connection Guidance).
15 Corps, “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal Register 41206, November 13,
(continued...)
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Waters of the United States (WOTUS): Frequently Asked Questions
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.16
One such Supreme Court case—Rapanos v. United States17—has been particularly relevant to the
efforts of the last several Administrations 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. 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.18 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 Scalia, and a “significant nexus” test proposed by
Justice Anthony Kennedy in a concurring opinion (see textbox below).19
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.20 Wetlands could be included only when they have a
“continuous surface connection” to such waters.21
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.22
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.23 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.24 Diverse stakeholders—including some Members of
Congress, states, the regulated community, and nongovernmental organizations—requested a
formal rulemaking to revise the existing rules.25 The Corps and EPA, under successive
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).
16 Corps and EPA, “Appendix A, Joint Memorandum,” 68 Federal Register 1995, January 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, December 2, 2008 (hereinafter 2008 Rapanos
Guidance); 2025 Continuous Surface Connection Guidance.
17 547 U.S. 715 (2006).
18 Id. at 719, 757 (Roberts, C.J., concurring), 759 (Kennedy, J., concurring).
19 Id. at 739, 782 (Kennedy, J., concurring).
20 Id. at 739.
21 Id. at 742.
22 Id. at 782 (Kennedy, J., concurring).
23 2008 Rapanos Guidance; see also Rapanos, 547 U.S. at 810 (Stevens, J., dissenting).
24 2015 Clean Water Rule, p. 37056.
25 See EPA, “What the Clean Water Rule Does,” EPA Web Archive, https://archive.epa.gov/epa/cleanwaterrule/what(continued...)
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Administrations—including the Obama Administration, the first Trump Administration, and the
Biden Administration—have promulgated new regulations to define WOTUS, but each of these
regulations has been debated and challenged in court.
As discussed in more detail in later sections (see “Which Rule Is in Effect Now?”), the pre-2015
regulations, consistent with the Supreme Court ruling in Sackett v. EPA, are currently in effect in
26 states that are participating in a pending litigation rule related to the Biden Administration’s
rule to define WOTUS. The 2023 WOTUS Rule, as amended by the 2023 Conforming Rule,
discussed below (see “2023 WOTUS Rule and 2023 Conforming Rule”), is in effect in the
remaining 24 states, the District of Columbia, and the U.S. territories.
2015 Clean Water Rule
In 2015, under the Obama Administration, the Corps and EPA issued the Clean Water Rule, which
redefined WOTUS in the agencies’ regulations for the first time since the 1980s.26 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.27
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.28
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.29 Two
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.30 As a result, until its rescission in 2019 (see below), 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 first 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.31 In
Step One, the Corps and EPA rescinded the Clean Water Rule and recodified the pre-2015
clean-water-rule-does.html; and EPA, Persons and Organizations Requesting Clarification of “Waters of the United
States” by Rulemaking, US EPA Archive Document, https://archive.epa.gov/epa/sites/production/files/2014-03/
documents/wus_request_rulemaking.pdf.
26 2015 Clean Water Rule.
27 2015 Clean Water Rule, pp. 37057-37059, 37105-37106.
28 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.
29 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. 1900564 (D. Or. July 26, 2019).
30 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.
31 For example, EPA, “EPA, U.S. Army Repeal 2015 Rule Defining ‘Waters of the United States’ Ending Regulatory
Patchwork,” press release, September 12, 2019, https://www.epa.gov/newsreleases/epa-us-army-repeal-2015-ruledefining-waters-united-states-ending-regulatory-patchwork.
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regulations.32 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.33 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.34 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.35
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.36 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
flaws.37 In response to the court’s 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.38
2023 WOTUS Rule and 2023 Conforming Rule
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.39 The rule went into
effect on March 20, 2023, but was immediately challenged.
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 regulations to reflect
32 Corps and EPA, “Definition of ‘Waters of the United States’—Recodification of Pre-Existing Rules,” 84 Federal
Register 56626, October 22, 2019.
33 Corps and EPA, “The Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’” 85 Federal
Register 22250, April 21, 2020.
34 Executive Order 13990, “Protecting Public Health and the Environment and Restoring Science to Tackle the Climate
Crisis,” 86 Federal Register 7037-7043, January 20, 2021.
35 EPA, “EPA, Army Announce Intent to Revise Definition of WOTUS,” press release, June 9, 2021,
https://www.epa.gov/newsreleases/epa-army-announce-intent-revise-definition-wotus; 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.
36 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.
37 Pascua Yaqui, 557 F. Supp. 3d at 955.
38 See EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,” https://www.epa.gov/
wotus/definition-waters-united-states-rule-status-and-litigation-update.
39 2023 WOTUS Rule.
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consideration of Supreme Court decisions, science, and the agencies’ experience and technical
expertise.40 Overall, the definition of WOTUS in the 2023 WOTUS Rule was narrower in scope
than in the Clean Water Rule and broader than in the Navigable Waters Protection Rule.
In May 2023, shortly after the issuance of the 2023 WOTUS Rule, the Supreme Court issued a
decision in a WOTUS-related case—Sackett v. EPA.41 As discussed in more detail below (see
“How Did Sackett v. EPA Affect the Scope of CWA Jurisdiction?”), the ruling significantly
narrowed the scope of WOTUS in comparison to all prior regulatory regimes. Most notably, the
Supreme Court rejected the significant nexus standard, adopted the Rapanos plurality’s relatively
permanent standard, and narrowed the scope of adjacent wetlands that are considered WOTUS.42
In response to the ruling, the Corps and EPA promulgated a new rule that amended the 2023
WOTUS Rule to conform the rule’s definition of WOTUS to the Sackett decision.43 The agencies
promulgated the rule (the 2023 Conforming Rule) without first publishing a proposed rule and
providing an opportunity for public notice-and-comment procedures. The rule went into effect on
September 8, 2023, the day it was published in the Federal Register.44
The 2023 WOTUS Rule, as amended by the 2023 Conforming Rule, is divided into three parts:
jurisdictional waters (WOTUS), exclusions, and definitions. These parts are summarized below
and compared to the pre-2015 regulations and guidance.
Jurisdictional Waters (WOTUS)
The 2023 WOTUS Rule, as amended by the 2023 Conforming Rule, includes seven WOTUS
categories (Table 1).45
Table 1. Description of Jurisdictional Waters (WOTUS) Under the 2023 WOTUS
Rule, as Amended by the 2023 Conforming Rule
Regulatory
Text
Paragrapha
Category of
WOTUS
Description
Traditional Navigable
Waters
Waters, such as large rivers and lakes, that are, were, or could be used in
interstate or foreign commerce, including waters affected by tides.
(a)(1)
Territorial Seas
The belt of the seas extending three miles out from the coast.
(a)(1)
Interstate Waters
Waters, such as rivers, lakes, or streams, that flow across or form part of
state boundaries.
(a)(1)
40 2023 WOTUS Rule, p. 3019; and 2022 WOTUS Fact Sheet.
41 Sackett v. EPA, 598 U.S. 651 (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.
42 Sackett, 598 U.S. at 678-79.
43 2023 Conforming Rule. The 2023 Conforming Rule does not rescind the 2023 WOTUS Rule, but rather amends the
provisions of the rule that were invalid under the Supreme Court’s interpretation of the CWA in Sackett.
44 2023 Conforming Rule. The Corps and EPA took the position that notice-and-comment procedures were not required
because the sole purpose of the 2023 Conforming Rule was to amend the 2023 WOTUS Rule to conform to Sackett,
and because the amendments did not involve the exercise of the agencies’ discretion. The Corps and EPA also stated
that good cause existed to make the rule immediately effective because the rule improved regulatory certainty and did
not impose burdens on the regulated community. 2023 Conforming Rule, p. 61965.
45 2023 Conforming Rule. See also Corps and EPA, Fact Sheet for the Final Rule: Amendments to the Revised
Definition of “Waters of the United States,” August 2023, https://www.epa.gov/system/files/documents/202308/FINAL_WOTUSPublicFactSheet08292023.pdf (hereinafter 2023 Conforming Rule Fact Sheet).
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Category of
WOTUS
Description
Regulatory
Text
Paragrapha
Impoundments of
Jurisdictional Waters
Impounded waters created in or from jurisdictional waters (other than
(a)(5) waters), whether natural (e.g., beaver ponds) or artificial (e.g.,
reservoirs).
(a)(2)
Tributaries
Waters, such as branches of creeks, streams, rivers, lakes, ponds, ditches,
and impoundments, that flow into traditional navigable waters, the
territorial seas, interstate waters, or impoundments of jurisdictional
waters. Tributaries are WOTUS if they meet the relatively permanent
standard.
(a)(3)
Adjacent Wetlands
Wetlands that are (1) adjacent to a traditional navigable water, the
territorial seas, or an interstate water; or (2) adjacent and with a
continuous surface connection to either relatively permanent
jurisdictional impoundments or jurisdictional tributaries that meet the
relatively permanent standard.
Wetlands, as defined in the rule, generally include swamps, marshes, bogs,
and similar areas. Adjacent is defined in the rule to mean “having a
continuous surface connection.” Therefore, in order to be jurisdictional,
wetlands adjacent to traditional navigable waters, interstate waters, or the
territorial seas must also have a continuous surface connection with those
waters.
(a)(4)
“Additional
waters”—intrastate
lakes and ponds,
streams, or wetlands
Intrastate lakes and ponds that do not fall under one of the other
WOTUS categories. Such waters are jurisdictional if they meet the
relatively permanent standard and have a continuous surface connection
to certain jurisdictional waters—(a)(1) or (a)(3) waters.
(a)(5)
Sources: CRS analysis; Army Corps of Engineers (Corps) and Environmental Protection Agency (EPA), “Revised
Definition of ‘Waters of the United States,’” 88 Federal Register 3004, January 18, 2023; Corps and EPA, Final Rule:
Revised Definition of “Waters of the United States” Fact Sheet, December 2022; Corps and EPA, “Revised Definition
of ‘Waters of the United States’; Conforming,” 88 Federal Register 61964, September 8, 2023; Corps and EPA,
Fact Sheet for the Final Rule: Amendments to the Revised Definition of “Waters of the United States,” August 2023.
Notes: WOTUS = waters of the United States.
a. Agency regulations defining WOTUS are codified at 33 C.F.R. § 328.3 and at 40 C.F.R. § 120.1.
Traditional Navigable Waters, the Territorial Seas, and Interstate Waters
(Paragraph (a)(1) Waters)
The 2023 WOTUS Rule retained three categories without changes to the text or substance from
pre-2015 regulations.46 These categories include 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.47
In the 2023 Conforming Rule, the Corps and EPA deleted interstate wetlands from the interstate
waters category to align with the ruling in Sackett.48 In contrast, the text of the pre-2015
regulations still includes interstate wetlands as part of the interstate waters category.49 However,
46 2023 WOTUS Rule, p. 3068.
47
2023 WOTUS Rule, p. 3068.
48 2023 Conforming Rule, p. 61966.
49 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774.
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the Corps and EPA have indicated that even where the pre-2015 regulations are in place, the
agencies are interpreting WOTUS consistent with Sackett.50 As specified in a September 27,
2023, guidance memorandum, “under the pre-2015 regulatory regime, consistent with Sackett, the
agencies ... will not assert jurisdiction over interstate wetlands solely because they are
interstate.”51
Impoundments of Jurisdictional Waters
The 2023 WOTUS Rule also retained the impoundments of jurisdictional waters category with
one change from the pre-2015 regulations.52 The pre-2015 regulations included impoundments of
any WOTUS, but the 2023 WOTUS Rule excluded impoundments of waters determined to be
jurisdictional under paragraph (a)(5), which the Corps and EPA in their fact sheet referred to as
“additional waters.”53 These “additional waters” are a subset of what was previously referred to as
the “other waters” category. (See further discussion on “additional waters” below.) The 2023
Conforming Rule did not make any changes to the impoundments of jurisdictional waters
category.54
Tributaries, Adjacent Wetlands, and “Additional Waters”
The remaining three categories in the 2023 WOTUS Rule—tributaries, adjacent wetlands, and
“additional waters”—reflect the definition of WOTUS from pre-2015 regulations, but include
changes that reflect Supreme Court precedent, science, and the Corps and EPA’s technical
expertise, according to the agencies.55 For example, the 2023 WOTUS Rule clarified that the
waters in these three categories could meet either the relatively permanent standard or the
significant nexus standard for purposes of determining jurisdiction.56
However, in the 2023 Conforming Rule, the Corps and EPA removed the significant nexus
standard to align with the ruling in Sackett. Accordingly, the waters in these three categories must
meet the relatively permanent standard to be jurisdictional. Guidance applicable to areas where
the pre-2015 regulations are in place also specifies that “the agencies will not assert jurisdiction
based on the significant nexus standard.”57 In addition to changes specific to the jurisdictional
tests, in promulgating the 2023 WOTUS Rule, the agencies also made certain changes to each of
the categories that constrained which waters are jurisdictional, in comparison to the pre-2015
regulations. These changes are described below.
Tributaries. A tributary is considered a WOTUS under the 2023 WOTUS Rule, as amended by
the 2023 Conforming 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 the relatively
50 EPA, “Pre-2015 Regulatory Regime,” https://www.epa.gov/wotus/pre-2015-regulatory-regime.
51 Corps and EPA, Joint Coordination Memorandum to the Field Between the U.S. Department of the Army, U.S. Army
Corps of Engineers (Corps) and the U.S. Environmental Protection Agency (EPA), September 27, 2023, p. 2,
https://www.epa.gov/system/files/documents/2023-10/2023-joint-coordination-memo-pre-2015-regulatoryregime_508c.pdf (hereinafter Joint Coordination Memorandum to the Field, September 27, 2023).
52 2023 WOTUS Rule, pp. 3075-3076.
53 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774; 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.
54 2023 Conforming Rule, p. 61968.
55
2023 WOTUS Rule, pp. 3005-3006; and 2022 WOTUS Fact Sheet.
56 2023 WOTUS Rule, pp. 3005-3006; and 2022 WOTUS Fact Sheet.
57 Joint Coordination Memorandum to the Field, September 27, 2023, p. 2.
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permanent standard.58
As compared to the pre-2015 regulations, the 2023 WOTUS Rule, as amended by the 2023
Conforming Rule, added the territorial seas to the list of waters to which a water may be a
tributary. The agencies stated that, in practice, this was not a significant change, as most
tributaries will reach a traditional navigable water before they reach the territorial seas.59
The 2023 WOTUS Rule, as amended by the 2023 Conforming Rule, also deletes the “additional
waters” category from the list of waters to which a water may be a tributary.60 The pre-2015
regulations included the comparable “other waters” category on the list, and the “other waters”
category itself was broader, as discussed below.61
Similar to the pre-2015 regulations, the 2023 WOTUS rule, as amended by the 2023 Conforming
Rule, does not contain a definition of tributary in the rule text.62 The 2023 WOTUS rule,
consistent with the pre-2015 regulations, also did 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).63
However, following the Sackett ruling, the Corps and EPA indicated that in eliminating the
significant nexus test, jurisdictional tributaries must meet the relatively permanent standard.64
This is true for areas that fall under the 2023 WOTUS Rule, as amended by the 2023 Conforming
Rule, as well as in areas that fall under the pre-2015 regime.65 The agencies defined “relatively
permanent” in the 2023 WOTUS Rule preamble to encompass “surface waters that have flowing
or standing water year-round or continuously during certain times of the year.”66 The agencies
further specified that “relatively permanent waters do not include surface waters with flowing or
standing water for only a short duration in direct response to precipitation.”67
Adjacent wetlands. Under the 2023 WOTUS Rule, as amended by the 2023 Conforming Rule,
adjacent wetlands are considered WOTUS if (1) they are adjacent to traditional navigable waters,
interstate waters, or the territorial seas; or (2) they are adjacent to and have a continuous surface
connection to jurisdictional impoundments or tributaries that meet the relatively permanent
58 2023 WOTUS Rule, p. 3142; 2023 Conforming Rule, pp. 61966, 61968.
59 2023 WOTUS Rule, pp. 3079-3080.
60 2023 WOTUS Rule, pp. 3079-3080.
61 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774.
62 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 asserted that they “articulate[d] and explain[ed] the agencies’ wellestablished interpretation and practices for identifying tributaries” in the preamble.
63 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
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.
64 2023 Conforming Rule, pp. 61965-61966, 61968.
65 Corps and EPA, “Updates for Tribes and States on Waters of the United States,” presentation, November 15, 2023,
https://www.epa.gov/system/files/documents/2023-11/wotus-overview_tribes-and-states_11-15-23_508.pdf, pp. 23-26.
66 2023 WOTUS Rule, p. 3084.
67 2023 WOTUS Rule, p. 3084.
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standard.68 The 2023 Conforming Rule also redefined adjacent to mean “having a continuous
surface connection.”69 The new definition for adjacent means that wetlands must have a
continuous surface connection to traditional navigable waters, interstate waters, or the territorial
seas to be jurisdictional.
The pre-2015 regulations more broadly included wetlands adjacent to waters in any of the
WOTUS categories, other than wetlands themselves, and had a broader definition of “adjacent.”70
(Note that the 2008 Rapanos Guidance provided additional specifics as to which wetlands were
WOTUS, as discussed in Table 2.) However, following the Sackett ruling, the Corps and EPA
issued a number of guidance documents clarifying which adjacent wetlands are considered
jurisdictional under both the pre-2015 regime and under the 2023 WOTUS Rule, as amended by
the 2023 Conforming Rule.71
On March 12, 2025, the Corps and EPA issued guidance (the 2025 Continuous Surface
Connection Guidance) specific to implementation of the continuous surface connection
requirement.72 Specifically, the guidance provides that for an adjacent wetland to be
jurisdictional,
First, the adjacent body of water must be a “water of the United States,” which generally
means traditional navigable waters, or a relatively permanent body of water connected to
a traditional navigable water. Second, the wetland, assuming it satisfies the agencies’
longstanding regulatory definition of “wetlands” ... must have a continuous surface
connection to a requisite covered water making it difficult to determine where the water
ends and wetland begins.73
“Additional waters.” Under the 2023 WOTUS Rule, as amended by the 2023 Conforming Rule,
intrastate lakes and ponds not identified in the other WOTUS categories must meet the relatively
permanent standard and have a continuous surface connection to traditional navigable waters, the
territorial seas, interstate waters, or jurisdictional tributaries.74 The agencies clarified in the 2023
WOTUS Rule preamble that this category is substantially narrower than the nonexclusive list of
“other waters” that was included under the pre-2015 regulations.75 The agencies also noted in the
2023 WOTUS Rule preamble that they replaced the broad Commerce Clause basis for
jurisdiction from the pre-2015 regulations with the relatively permanent and significant nexus
standards.76 The 2023 Conforming Rule further limited the basis to the relatively permanent
standard.77
68 2023 WOTUS Rule, p. 3142; 2023 Conforming Rule, pp. 61966, 61968.
69 2023 Conforming Rule, p. 61969.
70 1986 Corps Rule, pp. 41250-41251; 1988 EPA Rule, p. 20774.
71 EPA, “Current Implementation of Waters of the United States,” section on “Guidance Documents and Memoranda
Used to Implement the Current Definition of ‘Waters of the United States,’” https://www.epa.gov/wotus/currentimplementation-waters-united-states#Guidance.
72 2025 Continuous Surface Connection Guidance.
73 2025 Continuous Surface Connection Guidance, p. 5.
74 2023 WOTUS Rule, p. 3142; 2023 Conforming Rule, pp. 61966, 61968.
75 2023 WOTUS Rule, p. 3097.
76 2023 WOTUS Rule, p. 3097. The pre-2015 regulatory framework included as jurisdictional waters those waters “the
use, degradation, or destruction of which could affect interstate or foreign commerce.” 1986 Corps Rule, p. 41250;
1988 EPA Rule, p. 20774.
77 2023 Conforming Rule, pp. 61966, 61968.
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Exclusions
The 2023 WOTUS Rule provides eight exclusions from the definition of WOTUS.78 The 2023
Conforming Rule did not make any changes to these exclusions.79 Some are long-standing
exclusions for prior converted cropland and waste treatment systems that were codified in pre2015 regulatory text. Others exclude features that were generally considered nonjurisdictional
under the pre-2015 regime, but that were listed as such in preamble language and guidance rather
than in the regulatory text.80 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.81 The exclusions
include
•
•
•
•
•
•
•
•
waste treatment systems, including treatment ponds or lagoons designed to
meet the requirements of the CWA;
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 that 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.82 The
Food Security Act includes a provision (the “Swampbuster” exception) that requires USDA to
78 2023 WOTUS Rule, pp. 3066-3067, 3142-3143.
79 2023 Conforming Rule; 2023 Conforming Rule Fact Sheet.
80 2023 WOTUS Rule, pp. 3066-3067, 3142-3143.
81 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.
82 2023 WOTUS Rule, pp. 3105-3107. In 1993, the Corps and EPA codified into regulation the existing policy that
prior converted cropland (PCC) is not WOTUS. See Corps and EPA, “Clean Water Act Regulatory Programs,” 58
Federal Register 45008, August 25, 1993. In the rule’s preamble, the agencies referenced the definition of PCC from
USDA’s 1988 National Food Security Act Manual, which defines PCC as wetlands that “were both manipulated
(drained or otherwise physically altered to remove excess water from the land) and cropped before 23 December 1985,
to the extent that they no longer exhibit important wetland values.” For more information on the CWA PCC exclusion,
see CRS In Focus IF11136, Prior Converted Cropland Under the Clean Water Act, by Laura Gatz and Megan Stubbs.
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make determinations about whether wetland areas qualify as prior converted cropland.83 The
regulatory text in the 2023 WOTUS Rule specified that prior converted cropland designated by
USDA is excluded. The regulatory text also clarified that the exclusion would cease upon a
change of use, meaning the area is no longer available for the production of agricultural
commodities.84 This change aligns the WOTUS regulatory exclusion with the Swampbuster
exception for prior converted cropland.85 The 2023 Conforming Rule did not make any changes
to the prior converted cropland exemption.86
Definitions
The 2023 WOTUS Rule included six definitions. Five of the six definitions were unchanged from
the pre-2015 regulations, including the definitions for wetlands, adjacent, high tide line, ordinary
high water mark, and tidal water.87 The 2023 WOTUS Rule also newly defined the term
significantly affect for purposes of determining whether a water met the significant nexus
standard.88
The 2023 Conforming Rule deleted the definition for significantly affect, and it revised the
definition of adjacent, as noted above, to mean “having a continuous surface connection.”89 The
2023 Conforming Rule made no changes to the remaining four definitions.90
Which Rule Is in Effect Now?
The 2023 WOTUS Rule went into effect on March 20, 2023, and the 2023 Conforming Rule went
into effect on September 8, 2023.91 Litigation has changed which rule is in effect in some states,
however. Two federal district courts issued preliminary injunctions that collectively bar
implementation of the 2023 WOTUS Rule in 26 states.92 Following the issuance of the 2023
Conforming Rule, the Corps and EPA stated that they would interpret WOTUS consistent with
the pre-2015 regulatory regime and the decision in Sackett v. EPA as to those 26 states.93 As to the
other 24 states, the District of Columbia, and the U.S. territories, the Corps and EPA have stated
83 For more information, see CRS In Focus IF11136, Prior Converted Cropland Under the Clean Water Act, by Laura
Gatz and Megan Stubbs.
84 2023 WOTUS Rule, p. 3142.
85 2023 WOTUS Rule, pp. 3105-3107.
86
2023 Conforming Rule; 2023 Conforming Rule Fact Sheet.
87 2023 WOTUS Rule, pp. 3067, 3143.
88 2023 WOTUS Rule, pp. 3067, 3143.
89 2023 Conforming Rule, pp. 61966, 61969. See also 2023 Conforming Rule Fact Sheet.
90 2023 Conforming Rule; 2023 Conforming Rule Fact Sheet.
91 2023 Conforming Rule, p. 61964.
92 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. In addition to the district court preliminary injunctions, the U.S.
Court of Appeals for the Sixth Circuit stayed the 2023 WOTUS Rule pending appeal as to Kentucky and several
industry associations that were plaintiffs in that lawsuit, as well as to their members. Order, Kentucky v. EPA, No. 235343 (6th Cir. May 10, 2023), ECF No. 24. On September 23, 2024, after remanding the matter to the district court, the
Sixth Circuit issued a mandate lifting the stay order, bringing the number of states subject to the pre-2015 regulations
down from 27 to 26. Mandate, Kentucky v. EPA, No. 23-5343 (6th Cir. Sept. 23, 2024), ECF No. 57.
93 EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,”
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
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that they are implementing the 2023 WOTUS Rule, as amended by the 2023 Conforming Rule.94
Figure 1 shows which regulatory regime is operative in each state across the United States.
Figure 1. Status of the Waters of the United States (WOTUS) Regulatory Regime in
Effect as of June 23, 2025
Source: CRS.
The Supreme Court’s decision in Sackett v. EPA did not directly affect the status of the 2023
WOTUS Rule.95 The majority’s opinion nevertheless rejected jurisdictional interpretations that
were reflected in the 2023 WOTUS Rule, as well as in aspects of prior regulatory frameworks,
which all extended jurisdiction to more wetlands than were covered under the Sackett majority’s
interpretation. Following the Court’s decision, the Corps and EPA issued the 2023 Conforming
Rule, to align the definition of WOTUS to Sackett, and stated that they “will interpret the phrase
‘waters of the United States’ consistent with the Supreme Court’s decision.”96
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 and the 2023
Conforming 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.97 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
94 EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,”
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
95 See infra, “How Did Sackett v. EPA Affect the Scope of CWA Jurisdiction?”
96 EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,”
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
97 See 33 C.F.R. § 331.2.
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revision, or unless a recipient of an AJD (e.g., a landowner or project proponent) requests that a
new AJD be provided pursuant to the current regulatory regime.98 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.
Have the 2023 WOTUS Rule or 2023 Conforming
Rule Been Challenged in Court?
Five pending lawsuits challenge the 2023 WOTUS Rule and the 2023 Conforming Rule.99 While
no court to date has issued a ruling on the merits, preliminary orders have limited the
implementation of the 2023 WOTUS Rule for some states. All of the pending litigation has been
stayed while the Trump Administration considers taking further action with respect to the scope
of WOTUS.
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.100 In the first suit, the States of Texas and Idaho
argue that the 2023 WOTUS Rule unlawfully expands the Corps and EPA’s jurisdiction beyond
the bounds of the CWA; violates the major questions doctrine,101 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.102
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;103 exceeds the Corps’ and EPA’s statutory authority; and unlawfully fails to include a
regulatory flexibility analysis.104 An environmental group has intervened in the lawsuits in
support of the Corps and EPA.105
98 See EPA, “Current Implementation of Waters of the United States,” 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).
99 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. Dep’t 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.
100 Order, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 13, 2023), ECF No. 27.
101 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.
102 First Amended, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 27, 2023), ECF No. 32.
103 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 Congressional Research Service, “ArtI.S1.5. Nondelegation Doctrine,” Constitution Annotated,
https://constitution.congress.gov/browse/article-1/?anchor=I_S1_5#I_S1_5.
104 First Amended Complaint, Am. Farm Bureau Fed’n v. EPA, No. 3:23-cv-00020 (S.D. Tex. Feb. 2, 2023), ECF No.
1.
105 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.
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Third, a group of 24 states challenged the 2023 WOTUS Rule in the U.S. District Court for the
District of North Dakota.106 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.107 The agricultural and industry groups challenging the rule in
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.108
Fourth, the Commonwealth of Kentucky 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.109 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.110
The plaintiffs in each lawsuit filed motions asking the courts to bar implementation of the 2023
WOTUS Rule while the litigation is pending.111 Two district courts 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.112
In granting Texas and Idaho’s motion, the Texas district court stated that the 2023 WOTUS Rule
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.113 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.114
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
106 Complaint, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Feb. 16, 2023), ECF No. 1.
107 Id.
108 Order and Federal Defendants’ Appeal from the Magistrate Judge’s Order Granting Industry’s Motion to Intervene,
West Virginia v. EPA (D.N.D. Mar. 22, 2023 and Apr. 5, 2023), ECF Nos. 110 and 129.
109 Complaint, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 22, 2023), ECF No. 1.
110 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.
111 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, 2023 and
Feb. 28, 2023), ECF Nos. 10 and 17.
112 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. The North Dakota industry plaintiffs withdrew their motion for preliminary
injunction after the district court granted the state plaintiffs’ motion. Intervenor-Plaintiffs’ Notice of Withdrawal of
Their Motion for Preliminary Injunction, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Apr. 18, 2023), ECF No.
135.
113 Memorandum Opinion and Order Granting Preliminary Injunction at 19-26, Texas v. EPA.
114 Id. at 34.
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statutory authority, arbitrary and capricious, and in conflict with various constitutional
limitations.115
The litigation in Kentucky proceeded differently. In March 2023, the Kentucky district court
denied both preliminary injunction motions without prejudice and dismissed Kentucky’s and the
industry plaintiffs’ claims.116 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.117
Both Kentucky and the industry plaintiffs 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.118 On July 29, 2024, the Sixth
Circuit vacated the district court’s ruling.119 The Sixth Circuit ruled that the district court had
improperly dismissed the plaintiffs’ complaints and remanded the matter to the district court with
instructions that the plaintiffs file notice of their intent to file a new suit, amend their complaint,
“or dispense with this litigation altogether” in light of the Corps and EPA’s issuance of the 2023
Conforming Rule.120
Following the issuance of the 2023 Conforming Rule, plaintiffs in the pending cases have
amended their complaints to argue that the 2023 WOTUS Rule as amended remains unlawful.121
The plaintiffs argue, among other things, that the relatively permanent standard as stated in the
amended rule is vague and overly broad and that the agencies failed to adhere to notice-andcomment requirements in issuing the 2023 Conforming Rule.122
As a result of the preliminary injunctions, the pre-2015 regulations, consistent with Sackett, are in
effect in 26 states. Further proceedings in any of the pending lawsuits could increase or decrease
the number of states in which the 2023 WOTUS Rule and the 2023 Conforming Rule are in
effect.123 Further proceedings within the context of the pending lawsuits could also address
whether the 2023 Conforming Rule adequately amends the 2023 WOTUS Rule to conform to the
Supreme Court’s ruling in Sackett. It is also possible that no court will reach the merits of the
plaintiffs’ challenges to the 2023 WOTUS Rule as amended. After the change in Administration
115 Order Granting Plaintiffs’ Motion for Preliminary Injunction at 17-29, West Virginia v. EPA.
116 Opinion and Order, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Mar. 31, 2023), ECF No. 51.
117 Id. at 1.
118 Order, Kentucky v. EPA, No. 23-5343 (6th Cir. May 10, 2023), ECF No. 24.
119 Kentucky v. EPA, No. 23-5343, 2024 WL 3569525 (6th Cir. Jul. 29, 2024).
120 Id. at *2.
121 Second Amended Complaint and Petition for Review, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Nov. 13, 2023),
ECF No. 90; Second Amended Complaint for Declaratory Relief, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Nov.
13, 2023), ECF No. 91; Amended Complaint, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Nov. 13, 2023), ECF
No. 176; Intervenor Plaintiffs’ Amended Complaint for Declaratory Relief, West Virginia v. EPA, No. 3:23-cv-00032
(D.N.D. Nov. 13, 2023), ECF No. 175; First Amended Complaint, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky.
Nov. 8, 2024), ECF No. 78. Following the Sixth Circuit’s ruling, the industry plaintiffs in the Kentucky litigation
voluntarily dismissed their suit. Private-Sector Plaintiffs’ Notice of Voluntary Dismissal Without Prejudice, Kentucky
v. EPA, No. 3:23-00007 (E.D. Ky. Oct. 4, 2024), ECF No. 73.
122 E.g., Second Amended Complaint and Petition for Review, Texas v. EPA, No. 3:23-cv-00017 ¶¶ 77-79 (S.D. Tex.
Nov. 13, 2023), ECF No. 90; Second Amended Complaint for Declaratory Relief, Texas v. EPA, No. 3:23-cv-00017
¶ 9 (S.D. Tex. Nov. 13, 2023), ECF No. 91.
123 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.
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in 2025, the Corps and EPA asked the courts to stay each case to allow the agencies time to brief
new leadership about the issues presented in the case; in the Kentucky litigation, the parties also
sought to extend the stay following the issuance of the 2025 Continuous Surface Connection
Guidance to allow the agencies to conduct listening sessions, receive public comments, and take
further action as appropriate.124 All three district courts have granted stays, pausing the litigation
pending further action by the parties or the courts.125
How Did 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.126 In Sackett, landowners in Idaho (the
Sacketts) 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.127
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.”128
The majority also held that the CWA covers only wetlands that qualify as WOTUS “in their own
right.”129 This limited covered wetlands to those that are “indistinguishably part of a body of
water that itself constitutes ‘waters’ under the CWA.”130 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
124 Defendants’ Motion to Stay the Case or, in the Alternative, to Extend the Supplemental Briefing Deadline by 14
Days, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 3, 2025), ECF No. 135; Defendants’ Motion to Stay Case,
West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Feb. 4, 2025), ECF No. 250; Defendants’ Consent Motion to Stay
Case, Kentucky v. EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 3, 2025), ECF No. 89; Joint Status Report, Kentucky v.
EPA, No. 3:23-cv-00007 (E.D. Ky. Mar. 28, 2025), ECF No. 92.
125 Order, Texas v. EPA, No. 3:23-cv-00017 (S.D. Tex. Feb. 4, 2025), ECF No. 136; Order Granting Defendants’
Motion for Stay, West Virginia v. EPA, No. 3:23-cv-00032 (D.N.D. Feb. 18, 2025), ECF No. 256; Order, Kentucky v.
EPA, No. 3:23-cv-00007 (E.D. Ky. Feb. 10, 2025), ECF No. 90; Order, Kentucky v. EPA, No. 3:23-cv-00007 (E.D.
Ky. Apr. 3, 2025).
126 Sackett v. EPA, 598 U.S. 651 (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.
127 Sackett v. EPA, 8 F.4th 1075 (9th Cir. 2021).
128
Sackett v. EPA, 598 U.S. at 671.
129 Id. at 676.
130 Id.
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Waters of the United States (WOTUS): Frequently Asked Questions
waters of the United States in their own right, so that there is no clear demarcation between
waters and wetlands.131
Accordingly, the majority ruled that CWA jurisdiction excludes wetlands that are neighboring to
but separate from traditional navigable waters.132
In addition to reaffirming the Rapanos plurality’s standard, the majority also rejected the
significant nexus test.133 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.”134
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.”135
The Court’s ruling narrowed the scope of jurisdiction under the CWA as compared to its longstanding regulatory implementation and narrowed the interpretation adopted by lower courts postRapanos. While the precise extent of the change will continue to depend on how the Corps and
EPA implement various aspects of the decision (including through guidance or a new rule), 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.136 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 did not automatically affect the status of the 2023 WOTUS Rule.
The majority opinion nevertheless rejected jurisdictional interpretations that were reflected in the
2023 WOTUS Rule as well as in certain elements of the pre-2015 operative definition of
WOTUS. The 2023 Conforming Rule and implementation guidance issued by the Corps and EPA
(including the 2025 Continuous Surface Connection Guidance, discussed below under “What
Actions Has the Second Trump Administration Taken to Define WOTUS?”) both represent efforts
by the Corps and EPA to address the interpretation of WOTUS in light of Sackett.
The Supreme Court’s ruling could affect—and, in some cases, already has affected—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 cover more waters in their own programs.137 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; in some cases, states
have already expanded protections.138 Other states have enacted laws barring environmental state
131 Id. at 678.
132 Id. at 679.
133 Id.
134 Id. at 680.
135 Id. at 681.
136 Id. at 720 (Kavanaugh, J., concurring in the judgment).
137 33 U.S.C. § 1370.
138 E.g., California State Water Resources Control Board, “State Water Board Statement: U.S. Supreme Court Decision
Decreases Federal Wetlands Protection,” press release, May 25, 2023,
https://waterboards.ca.gov/press_room/press_releases/2023.html. On June 4, 2025, the California Senate passed a bill
(SB 601) to protect certain state waterways following Sackett, but the bill had not been enacted into law at the time of
publication of this report. In May 2024, Colorado became the first state to enact legislation restoring protections to
certain wetlands and streams following the Sackett decision (Colorado House Bill 24-1379).
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agencies from promulgating regulations beyond what is federally required.139 A narrowed
definition of WOTUS at the federal level could thus result in greater state-level divergence in the
scope of covered waters.
What Actions Has the Second Trump
Administration Taken to Define WOTUS?
On March 12, 2025, the second Trump Administration announced its intent to revise the
definition of WOTUS again through new rulemaking.140 In an EPA press release, the
Administration promised to ensure a revised definition that “follows the law, reduces red-tape,
cuts overall permitting costs, and lowers the cost of doing business in communities across the
country while protecting the nation’s navigable waters from pollution.”141 EPA also committed to
focus its regulatory revision on “clarity, simplicity and improvements that will stand the test of
time.”142
The same day, the Corps and EPA issued new guidance to field staff to help implement Sackett.143
The Administration asserted that the preamble to the 2023 Conforming Rule, and the agencies’
case-specific policy memoranda issued after Sackett under the Biden Administration, did not
provide clear or transparent direction for the public or the agencies on the meaning of the
continuous surface connection requirement.144 The guidance, a joint memorandum to field staff,
focused on implementation of the meaning of the continuous surface connection requirement for
determining which wetlands are considered jurisdictional adjacent wetlands.
The guidance reiterates the two-part test provided in the Sackett ruling for determining CWA
jurisdiction over adjacent wetlands: (1) the adjacent body of water must be a WOTUS, “which
generally means traditional navigable waters or a relatively permanent body of water connected
to a traditional navigable water”; and (2) the wetland “must have a continuous surface connection
to a requisite covered water making it difficult to determine where the water ends and the wetland
begins.”145 The guidance also clarifies that adjacent wetlands are WOTUS only if they directly
abut certain jurisdictional waters and are not separated from such waters by uplands, a berm, a
dike, or a similar feature.146
Additionally, the agencies rescinded prior guidance and training materials issued under the Biden
Administration that asserted that a wetland also has a continuous surface connection to a
jurisdictional water if it is connected to that water through a “discrete feature” (e.g., a
nonjurisdictional ditch, swale, pipe, or culvert). Per the new guidance, a wetland that has a
139 See Corps and EPA, Resource and Programmatic Assessment for the Navigable Waters Protection Rule: Definition
of “Waters of the United States,” January 23, 2020, pp. 45-46, https://www.epa.gov/sites/production/files/202001/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.
140 EPA, “Administrator Zeldin Announces EPA Will Revise Waters of the United States Rule,” press release,
March 12, 2025, https://www.epa.gov/newsreleases/administrator-zeldin-announces-epa-will-revise-waters-unitedstates-rule (hereinafter March 2025 EPA Press Release).
141 March 2025 EPA Press Release.
142 March 2025 EPA Press Release.
143 2025 Continuous Surface Connection Guidance.
144
2025 Continuous Surface Connection Guidance, p. 1.
145 2025 Continuous Surface Connection Guidance, p. 5.
146 2025 Continuous Surface Connection Guidance, p. 5.
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continuous surface connection to a jurisdictional water through a “discrete feature” but does not
abut the covered water is not jurisdictional.147
The Corps and EPA also announced a Federal Register notice publicizing a series of six listening
sessions and a 30-day recommendations docket to solicit feedback on key aspects of the
definition of WOTUS. The Corps and EPA published the Federal Register notice on March 24,
2025.148 It announced listening sessions for April and May 2025, as well as the availability of the
recommendations docket, opened until April 23, 2025, to accept written recommendations from
the public.149 The agencies organized the six listening sessions by stakeholder groups—states,
tribes, industry and agricultural stakeholders, environmental and conservation stakeholders, local
governments, and the public.150
How Have Adjacent Wetlands Been Addressed in
Each of the 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.151 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 summarizes the scope of adjacent wetlands in the pre-2015 regulations, the 2008
Rapanos Guidance, the 2015 Clean Water Rule, the 2020 Navigable Waters Protection Rule, the
2023 WOTUS Rule, the Sackett v. EPA decision, the 2023 Conforming Rule, and the 2025
Continuous Surface Connection Guidance.
147 2025 Continuous Surface Connection Guidance, p. 5.
148 Corps and EPA, “WOTUS Notice: The Final Response to SCOTUS; Establishment of a Public Docket; Request for
Recommendations,” 90 Federal Register 13428, March 24, 2025.
149 EPA Docket, “Implementation of the Definition of Waters of the United States,” EPA-HQ-OW-2025-0093,
https://www.regulations.gov/document/EPA-HQ-OW-2025-0093-0001/comment.
150 EPA, “Public Outreach and Stakeholder Engagement Activities,” https://www.epa.gov/wotus/public-outreach-andstakeholder-engagement-activities.
151 E.g., 1986 Corps Rule, pp. 41206, 41251.
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Table 2. Scope of Adjacent Wetlands Under Waters of the United States (WOTUS) Regulations and Guidance and in the
Sackett v. EPA Decision
Description of the Adjacent Wetlands
WOTUS Category
Source
Pre-2015
Regulationsa
2008 Rapanos
Guidancec
CRS-21
Wetlands adjacent to jurisdictional waters, other than
waters that are themselves wetlands
•
Wetlands that were adjacent to traditional
navigable waters and wetlands that abutted
relatively permanent tributaries (described as
those that flow year-round or have continuous
flow at least seasonally) of such waters were
categorically WOTUS
•
Wetlands adjacent to tributaries that were not
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
How Adjacent Is Defined
The regulations
•
define adjacent as “bordering, contiguous, or neighboring”b; and
•
specify that “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.
The guidance provided that adjacency was established by satisfying one of three criteria:
(1) the wetland had an unbroken surface or shallow subsurface connection to jurisdictional
waters (which may be intermittent);
(2) the wetland was physically separated from jurisdictional waters by man-made dikes or
barriers, natural river berms, beach dunes, or similar features; or
(3) the wetland’s proximity to a jurisdictional water was reasonably close and supported a
science-based inference of ecological interconnection.
Description of the Adjacent Wetlands
WOTUS Category
Source
2015 Clean Water
Ruled
•
•
2020 Navigable
Waters Protection
Rulee
CRS-22
Adjacent waters, including wetlands, ponds, lakes,
oxbows, impoundments, and similar waters,
rather than just adjacent wetlands
Included waters adjacent to traditional navigable
waters; interstate waters, including interstate
wetlands; jurisdictional impoundments; and
jurisdictional tributaries
Adjacent wetlands
How Adjacent Is Defined
The rule
•
defined adjacent to mean “bordering, contiguous, or neighboring” a traditional
navigable water, an interstate water (including an interstate wetland), a jurisdictional
impoundment, or a jurisdictional tributary;
•
included “waters separated by constructed dikes or barriers, natural river berms,
beach dunes, and the like”;
•
specified that for the purposes of adjacency, an open water such as a pond or lake
included any wetlands within or abutting its ordinary high water mark;
•
specified that adjacency was not limited to waters located laterally to a traditional
navigable water, an interstate water (including an interstate wetland), a 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 that
were located at the head of one of these waters and were bordering, contiguous, or
neighboring; and
•
newly defined neighboring, setting new numeric standards for determining adjacency—
waters were considered to be neighboring if they were located within 100 feet of the
ordinary high water mark of a traditional navigable water, an interstate water
(including an interstate wetland), a jurisdictional impoundment, or a jurisdictional
tributary; or if the water was located 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.
The rule defined adjacent wetlands to mean wetlands that
(1) abutted a territorial sea or traditional navigable water, tributary, or a lake, pond, or
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.
The rule specified that an adjacent wetland was jurisdictional when a road or similar
artificial structure divided the wetland, so long as the structure allowed for a direct
hydrologic surface connection through or over that structure in a typical year.
Source
2023 WOTUS Rulef
Sackett v. EPAg
Description of the Adjacent Wetlands
WOTUS Category
How Adjacent Is Defined
Wetlands that are adjacent to
(1) traditional navigable waters, interstate waters, or
the territorial seas;
(2) jurisdictional impoundments or tributaries that are
relatively permanent, standing, or continuously flowing
bodies of water and with a continuous surface
connection to those waters; or
(3) jurisdictional impoundments or tributaries when
the wetlands alone or in combination with similarly
situated waters meet the significant nexus standard
The rule
Adjacent wetlands that are part of (i.e.,
indistinguishable from) waters of the United States
The decision
•
defines adjacent as “bordering, contiguous, or neighboring”; and
•
specifies that 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.”
•
Specifies that adjacent wetlands include
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.
•
2023 Conforming
Ruleh
CRS-23
Wetlands adjacent to
(1) traditional navigable waters, interstate waters, or
the territorial seas; or
(2) jurisdictional impoundments or tributaries that are
relatively permanent, standing, or continuously flowing
bodies of water and with a continuous surface
connection to those waters
Excludes wetlands that are neighboring to but separate from traditional navigable
waters, such as those separated by a barrier.
The rule defines adjacent as “having a continuous surface connection.”
Source
2025 Continuous
Surface Connection
Guidancei
Description of the Adjacent Wetlands
WOTUS Category
Adjacent wetlands that have a continuous surface
connection because they directly abut certain
jurisdictional waters and are not separated from the
adjacent WOTUS by uplands, a berm, a dike, or a
similar feature
How Adjacent Is Defined
The guidance provides a two-part test for determining jurisdiction over adjacent wetlands:
•
the adjacent body of water must be a WOTUS, which generally means traditional
navigable waters or a relatively permanent body of water connected to a traditional
navigable water; and
•
the wetland (assuming it meets the long-standing regulatory definition) must have a
continuous surface connection to a requisite covered water, making it difficult to
determine where the water ends and the wetland begins.
Per the guidance, a wetland that has a continuous surface connection to a jurisdictional
water through a “discrete feature” (e.g., a nonjurisdictional ditch, swale, pipe, or culvert),
but does not abut the covered water, is not jurisdictional.
Source: CRS analysis of WOTUS regulations, WOTUS guidance, and the Sackett v. EPA decision.
Notes:
a. Army Corps of Engineers (Corps), “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal Register 41206, November 13, 1986 (1986 Corps
Rule); Environmental Protection Agency (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 does not define adjacent, but the 1986 Corps Rule defines it as described in the table.
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, December 2, 2008.
d. Corps and EPA, “Clean Water Rule: Definition of ‘Waters of the United States’; Final Rule,” 80 Federal Register 37054, June 29, 2015.
e. Corps and EPA, “The Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’” 85 Federal Register 22250, April 21, 2020.
f.
Corps and EPA, “Revised Definition of ‘Waters of the United States,’” 88 Federal Register 3004, January 18, 2023.
g. Sackett v. EPA, 598 U.S. 651 (2023).
h. Corps and EPA, “Revised Definition of ‘Waters of the United States’; Conforming,” 88 Federal Register 61964, September 8, 2023.
i.
Corps and EPA, Memorandum to the Field Between the U.S. Department of the Army, U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency Concerning
the Proper Implementation of “Continuous Surface Connection” Under the Definition of “Waters of the United States” Under the Clean Water Act, March 12, 2025,
https://www.epa.gov/system/files/documents/2025-03/2025cscguidance.pdf.
CRS-24
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 the decision 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 recent Congresses. In the 119th
Congress, the Senate Environment and Public Works Committee held a hearing on the federal
permitting process, which included a discussion of the implementation of the Sackett ruling and
WOTUS.152 The House Transportation and Infrastructure Committee’s Subcommittee on Water
Resources and Environment also held a hearing—more narrowly focused on CWA permitting—
which included a discussion of the definition of WOTUS and stakeholder views on the
implementation of the Biden Administration’s rules post-Sackett.153
In the 118th Congress, the Senate Environment and Public Works Committee held a hearing to
examine the implications of the Sackett decision for CWA protections of wetlands and streams,
and the House Transportation and Infrastructure Committee’s Subcommittee on Water Resources
and Environment held a hearing regarding the 2023 WOTUS Rule.154 Other committees held
hearings at which the topic of WOTUS was discussed, including a hearing held by the House
Committee on Agriculture.155
Members have also introduced legislation related to WOTUS in recent Congresses. In the 119th
Congress, S. 795, the Farmers Freedom Act of 2025, as introduced, would amend the CWA to
statutorily exclude prior converted cropland from the definition of WOTUS and codify details
about what conditions would lead prior converted cropland to lose its exemption status. H.R.
3898, the Promoting Efficient Review of Modern Infrastructure Today (PERMIT) Act, as
introduced, would codify four WOTUS exclusions—waste treatment systems (including
treatment ponds or lagoons), ephemeral features, prior converted cropland, and groundwater—
and would specify that the EPA Administrator or the Secretary of the Army, acting through the
Chief of Engineers, could determine other exclusions.
152 U.S. Congress, Senate Environment and Public Works Committee, Improving the Federal Environmental Review
and Permitting Process, hearing, 119th Cong., 1st sess., February 19, 2025.
153 U.S. Congress, House Transportation and Infrastructure Committee, Water Resources and Environment
Subcommittee, America Builds: Clean Water Act Permitting and Project Delivery, hearing, 119th Cong., 1st sess.,
February 11, 2025, H.Hrg. 119-6.
154 U.S. Congress, Senate Environment and Public Works Committee, Examining the Implications of Sackett v. U.S.
Environmental Protection Agency for Clean Water Act Protections of Wetlands and Streams, hearing, 118th Cong., 1st
sess., October 18, 2023, S.Hrg. 118-266; U.S. Congress, House Transportation and Infrastructure Committee, Water
Resources and Environment Subcommittee, Hearing on Stakeholder Perspectives on Impacts of the Biden
Administration’s Waters of the United States (WOTUS) Rule, 118th Cong., 1st sess., February 8, 2023.
155 U.S. Congress, House Committee on Agriculture, For the Purpose of Receiving Testimony from The Honorable
Michael Regan, Administrator, U.S. Environmental Protection Agency, hearing, 118th Cong., 1st sess., April 19, 2023.
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Waters of the United States (WOTUS): Frequently Asked Questions
In the 118th Congress, Members in both chambers introduced joint resolutions of disapproval of
the 2023 WOTUS Rule under the Congressional Review Act (CRA).156 In addition, some
Members introduced legislation that would have enacted the Navigable Waters Protection Rule’s
definition of WOTUS into law, reinstated the Navigable Waters Protection Rule, amended the
CWA to add a narrower definition of navigable waters, or amended the CWA to establish a
broader jurisdictional scope of waters protected under the statute. Other bills in the 118th
Congress would have established an agricultural advisory committee to inform Congress of the
impacts of WOTUS regulations on the agricultural sector, or would have required the Corps and
EPA to issue guidance on the implementation of the 2023 Conforming Rule.
Below are summaries of legislation related to WOTUS in the 118th Congress.
•
•
•
H.J.Res. 27 and S.J.Res. 7 were joint resolutions providing for congressional
disapproval of the 2023 WOTUS Rule under the CRA.157 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.158 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, were identical bills that would have amended the CWA to change the
definition of navigable waters. The language, as introduced, would have
narrowed the scope of waters subject to CWA jurisdiction in comparison to any
of the WOTUS regulatory regimes (pre-2015, Clean Water Rule, Navigable
Waters Protection Rule, and 2023 WOTUS Rule). It would also have amended
the CWA to make changes to the Corps process for making jurisdictional
determinations.
H.R. 5983, the Clean Water Act of 2023, would have replaced the term navigable
waters with protected water resources throughout the CWA. It also would have
defined the term protected water resources to mean
all waters subject to the ebb and flow of the tide, the territorial seas, and all interstate
and intrastate waters (and their tributaries), including lakes, rivers, streams (including
intermittent and ephemeral streams), wetlands, and all impoundments of the foregoing,
to the fullest extent that these waters are subject to the legislative power of Congress
under the Constitution.
•
H.R. 7023, the Creating Confidence in Clean Water Permitting Act, would have
required the Corps and EPA to issue guidance on the implementation of the 2023
Conforming Rule. It also would have required the agencies to solicit and respond
to public comment on the guidance prior to issuance.
156 5 U.S.C. §§ 801-808.
157 5 U.S.C. §§ 801-808. The CRA allows Congress to overturn certain agency actions in the form of a joint resolution
of disapproval. 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. For more information, see CRS In Focus
IF10023, The Congressional Review Act (CRA): A Brief Overview, by Maeve P. Carey and Christopher M. Davis.
158 See H.J.Res 27 under “Actions.”
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Waters of the United States (WOTUS): Frequently Asked Questions
•
•
•
•
•
S. 782, the FREE American Energy Act, would have enacted the Navigable
Waters Protection Rule into law.
S. 879, the Energy Freedom Act, would have reinstated the Navigable Waters
Protection Rule and provided that each of its provisions applied until the
effective date of a subsequent final rule. It would also have prohibited 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 have established 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 have amended the CWA to change the
definition of navigable waters. The language, as introduced, closely aligned with
the definition published in the Navigable Waters Protection Rule.
S. 3366, the Farmers Freedom Act of 2023, would have required the Corps and
EPA to ensure that any definition of WOTUS would exclude prior converted
cropland and would have the meaning given the term in the Navigable Waters
Protection Rule.
Moving forward, Congress has several options to take action regarding the definition of WOTUS,
in addition to the option of maintaining the status quo. Congress may oversee the Corps and
EPA’s efforts to implement existing regulations, including the 2023 WOTUS Rule, as amended by
the 2023 Conforming Rule, and the pre-2015 regulations implemented consistent with Sackett.
This may include oversight of guidance the Corps and EPA have issued or any new guidance the
agencies opt to issue. Given the second Trump Administration’s announcement to issue revised
regulations, Congress may also oversee the Corps and EPA’s efforts to promulgate such revised
regulations, as well as their efforts to implement the 2025 Continuous Surface Connection
Guidance.
Some in Congress may consider proposing legislation to either provide a definition of WOTUS or
provide more specific instruction to the agencies and regulated parties as to their interpretation of
the CWA, particularly given the challenges that each of the past three Administrations has faced
in establishing lasting regulations that could withstand legal challenges. Legislative proposals
could include providing a specific definition of WOTUS, specific exemptions from WOTUS,
and/or definitions of certain key terms that have been included in past and current regulations.
Alternatively, legislative proposals could clarify congressional intent for specific implementation
issues (e.g., what kinds of characteristics, such as flow duration, tributaries should have to be
jurisdictional).The Supreme Court’s increasing insistence on clear congressional intent to
delegate regulatory authority, and its elimination of the Chevron framework, which required
courts to defer to reasonable agency interpretations of ambiguous statutes,159 suggest that any
regulatory actions taken within the current statutory framework would be subject to close judicial
scrutiny. Amending the CWA to provide more specificity would allow Congress to choose the
policy it prefers rather than leaving the courts to interpret ambiguities in the statute.
159 Loper Bright Enters. v. Raimondo, 603 U.S. 369 (2024). For additional information, see CRS Report R48320, Loper
Bright Enterprises v. Raimondo and the Future of Agency Interpretations of Law, by Benjamin M. Barczewski. See
also West Virginia v. EPA, 597 U.S. 697 (2022).
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Waters of the United States (WOTUS): Frequently Asked Questions
Author Information
Kate R. Bowers
Section Research Manager
Laura Gatz
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
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This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.