Redefining Waters of the United States
September 30, 2021
(WOTUS): Recent Developments
Laura Gatz
Congress established the Federal Water Pollution Control Act, also known as the Clean Water
Analyst in Environmental
Act (CWA), to restore and protect the quality of the nation’s surface waters. The CWA protects
Policy
“navigable waters,” defined in the statute as “waters of the United States, including the territorial

seas.” The CWA does not further define the term waters of the United States (WOTUS), which
Kate R. Bowers
determines which waters are federally regulated. Thus, in implementing the CWA, the Army
Legislative Attorney
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.

For much of the past several decades, regulations promulgated by the Corps and EPA in the 1980s have been in effect. The
agencies supplemented these regulations with guidance developed in 2003 and 2008 in response to two Supreme Court
rulings—Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, in 2001, and Rapanos v. United
States, in 2006—which interpreted the CWA’s scope more narrowly than the Corps and EPA had done previously in
regulations and guidance, but also created uncertainty about the intended scope of waters protected by the CWA. 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 requested a formal rulemaking to
revise existing regulations.
In 2015, the Corps and EPA issued the Clean Water Rule, which redefined WOTUS in the agencies’ regulations for the first
time since the 1980s. While the Corps and EPA contended that the primary intent of the 2015 Clean Water Rule was to
clarify its regulatory jurisdiction, some stakeholders and observers viewed it as an expansion instead. Other stakeholders
argued that it excluded too many waters from federal jurisdiction. Industry groups, more than half the states, and several
environmental groups filed lawsuits challenging the Clean Water Rule in federal courts across the country.
The Trump Administration described the 2015 Clean Water Rule as an example of federal “overreach” and took steps to
rescind and revise it. On October 22, 2019, the Corps and EPA published a final rule to rescind the 2015 Clean Water Rule
and recodify the pre-2015 regulations (i.e., the 1980s regulations). On April 21, 2020, the agencies published a second final
rule to redefine WOTUS, the Navigable Waters Protection Rule, which went into effect on June 22, 2020. Overall, the
Navigable Waters Protection Rule narrowed the scope of waters that fell under federal jurisdiction. The Navigable Waters
Protection Rule prompted strong reactions from a variety of stakeholders, and numerous groups filed lawsuits challenging it.
The Biden Administration has taken steps to reconsider the Navigable Waters Protection Rule. President Biden issued an
executive order which revoked a Trump Administration executive order related to WOTUS and directed agencies to review
certain Trump Administration agency actions, including the Navigable Waters Protection Rule. On June 9, 2021, the Corps
and EPA announced their intent to initiate a new rulemaking process that would both restore the protections in place prior to
the 2015 Clean Water Rule and develop a new rule to establish a “durable” WOTUS definition. On July 30, 2021, the
agencies signed a notice of public meeting dates and solicitation of pre-proposal feedback from stakeholders regarding their
perspectives on defining WOTUS. On September 3, 2021, following a court order vacating the Navigable Waters Protection
Rule, the agencies announced that they had halted implementation of the rule and would interpret WOTUS consistent with
the pre-2015 regulatory regime.
Congress has shown continued interest in the scope of WOTUS. In the 116th and 117th Congresses, committees have held
hearings that discussed WOTUS, and some Members have introduced legislation regarding the definition of WOTUS.
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Redefining Waters of the United States (WOTUS): Recent Developments

Introduction
Congress 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 CWA protects
“navigable waters,” defined in the statute as “waters of the United States, including the territorial
seas.”2 The scope of this term—waters of the United States, or WOTUS—determines which
waters are federally regulated and has been the subject of debate for decades.3 The CWA does not
define the term. 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.
For several decades, successive presidential administrations have struggled to interpret the term
waters of the United States for the purpose of implementing various requirements of the CWA,
and courts have been asked repeatedly to review the regulations and policy expressing those
interpretations. Stakeholders have asked the various administrations and the courts to resolve
issues involving scope, clarity, consistency, and predictability. Some stakeholders argue against
any definition that would result in a broad scope of waters under federal jurisdiction and affect
the interests of property owners, farmers, and others.4 Other stakeholders argue that a definition
that results in too narrow of a scope of waters under federal jurisdiction would leave some
hydrologically connected waters and aquatic habitats unprotected.5
The agencies’ efforts to define WOTUS in regulation during both the Obama and Trump
Administrations have been mired in controversy and litigation. Many observers viewed the
Obama Administration’s 2015 Clean Water Rule as defining WOTUS too broadly, while many
viewed the Trump Administration’s 2020 Navigable Waters Protection Rule as defining WOTUS
too narrowly. A federal district court vacated the Navigable Waters Protection Rule in September
2021, after which the Corps and EPA announced that they had halted implementation of the rule.6
The Biden Administration has signaled its intent to pursue an “enduring definition” that considers
the implementation challenges presented by both of those rules. In light of these challenges, some
observers argue that the statutory terms navigable waters and waters of the United States are too
vague and should be more specifically defined by Congress or the courts. 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.
Actions by the courts, the Biden Administration, and Congress all have the potential to continue
to alter the scope of federal jurisdiction under the CWA. This report examines the actions taken

1 33 U.S.C. §1251 et seq.
2 CWA §502(7); 33 U.S.C. §1362(7).
3 For a more in-depth discussion of the federal regulations, legislation, agency guidance, and case law that have shaped
the meaning of waters of the United States over time, as well as an overview of associated key terminology, see CRS
Report R44585, Evolution of the Meaning of “Waters of the United States” in the Clean Water Act, by Stephen P.
Mulligan.
4 For example, see stakeholder support for the narrower definition under the Navigable Waters Protection Rule. EPA,
“More Widespread Support for EPA and Army’s Navigable Waters Protection Rule—A New Definition of WOTUS,”
press release, January 24, 2020, https://www.epa.gov/newsreleases/more-widespread-support-epa-and-armys-
navigable-waters-protection-rule-new-definition.
5 For example, see S. Mazeika Patricio Sullivan, Mark C. Rains, and Amanda D. Rodewald, et al., “Distorting science,
putting water at risk,” Science, vol. 369, no. 6505 (August 14, 2020), pp. 766-768. See also “Coalition of 17 state AGs
joins challenges to 2020 WOTUS rule,” InsideEPA.com, May 1, 2020.
6 Order, Pasqua Yaqui Tribe v. EPA, No. 4:20-cv-00266, Doc. No. 99 (D. Ariz. Aug. 30, 2021).
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by the Obama, Trump, and Biden Administrations to define waters of the United States, along
with related legislation and case law.
Recent History of WOTUS Regulations
Pre-2015 Rules and Guidance
For much of the past several decades, regulations promulgated by the Corps and EPA in 1986 and
1988, respectively, have been in effect.7 (These 1986 and 1988 regulations, as further interpreted
by the courts and agencies, are hereinafter referred to as pre-2015 rules.) The agencies
supplemented these regulations with interpretive guidance developed in response to two Supreme
Court rulings. Specifically, in 2001 and 2006, the Supreme Court issued rulings pivotal to the
definition of WOTUS—Solid Waste Agency of Northern Cook County v. U.S. Army Corps of
Engineers and Rapanos v. United States.8 Both rulings interpreted the scope of the CWA more
narrowly than the Corps and EPA had done previously in regulations and guidance, but Rapanos
in particular created uncertainty about the intended scope of waters that are protected by the
CWA. The Court’s decision in Rapanos yielded three different opinions, none of which garnered
a controlling majority for a single standard to govern future jurisdictional disputes. Instead,
writing for a plurality of four Justices, Justice Scalia adopted a rule that “waters” in “waters of the
United States” means only “relatively permanent, standing, or continuously flowing bodies of
water” (i.e., streams, rivers, and lakes), and wetlands with a “continuous surface connection” to
such waters.9 Justice Kennedy, writing alone, concluded that a case-by-case test that considers
ecological connection and requires a “significant nexus” between the water in question and
traditional navigable waters was appropriate.10 Justice Stevens, for the four dissenters, would
have upheld the existing reach of Corps/EPA regulations.11 Because the 4-1-4 split in Rapanos did
not produce a controlling majority opinion for a single jurisdictional test, lower courts have had to
parse the various opinions to decide which definition to apply.12
In response to the rulings, the agencies developed guidance in 200313 and 200814 to help clarify
how EPA regions and Corps districts should implement the Court’s decisions. In the 2008
guidance issued by the Corps and EPA following Rapanos, the agencies organized CWA
jurisdictional analysis into three categories:

7 U.S. Army Corps of Engineers, “Final Rule for Regulatory Programs of the Corps of Engineers,” 51 Federal Register
41206, November 13, 1986 (hereinafter “1986 Corps Rule”); EPA, “Clean Water Act Section 404 Program Definitions
and Permit Exemptions; Section 404 State Program Regulations,” 53 Federal Register 20764, June 6, 1988 (1988 EPA
Rule).
8 Solid Waste Agency of N. Cook Cnty. v. U.S. Army Corps of Eng’rs, 531 U.S. 159 (2001); Rapanos v. United States,
547 U.S. 715 (2006).
9 Rapanos, 547 U.S. at 739, 742.
10 Id. at 782 (Kennedy, J., concurring).
11 Id. at 788 (Stevens, J., dissenting).
12 See Mulligan, supra note 3, at 22-23.
13 Army Corps of Engineers and EPA, “Appendix A, Joint Memorandum,” 68 Federal Register 1995, January 15,
2003.
14 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
Guidance”).
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1. waters and wetlands that were categorically WOTUS;
2. waters and wetlands that may be WOTUS on a case-by-case basis upon
determining a “significant nexus” with a traditional navigable water; and
3. waters and wetlands that are categorically excluded from WOTUS.
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.”15 The agencies further acknowledged that case-by-case significant
nexus determinations were resource- and time-intensive.16 Diverse stakeholders—including
Members of Congress, states, the regulated community, and nongovernmental organizations—
requested a formal rulemaking to revise the existing rules.17
2015 Clean Water Rule
In 2015, the Corps and EPA issued the Clean Water Rule, which redefined WOTUS in the
agencies’ regulations for the first time since the 1980s.18 In publishing the 2015 Clean Water
Rule, the agencies sought to reduce the universe of waters subject to case-by-case jurisdictional
determinations.19 The 2015 Clean Water Rule retained aspects of the agencies’ 2008 guidance,
including a three-tiered jurisdictional analysis (i.e., categorically jurisdictional, jurisdictional on a
case-by-case basis upon determining a “significant nexus,” and categorically excluded).20 It also
incorporated new features, such as definitions and criteria which established when certain waters
were categorically WOTUS, subject to case-by-case significant nexus analysis, or categorically
excluded.21 Some of these changes expanded the set of waters that were categorically WOTUS.
For example, the 2015 Clean Water Rule newly defined tributaries.22 Under the 2015 Clean Water
Rule, tributaries were jurisdictional by rule if they had certain features that indicated flow (e.g., a
bed and bank and an ordinary high water mark) and contributed flow directly or indirectly to a
traditional navigable water, an interstate water, or the territorial seas.23 Under the 2015 Clean
Water Rule, a tributary could be perennial (i.e., flow year-round), intermittent (i.e., flow
continuously only during certain times of year, such as seasonally), or ephemeral (i.e., flow only
in response to precipitation events) as long as the criteria in the definition were met.24 Under pre-
2015 rules and guidance, tributaries were jurisdictional by rule if they were perennial or
intermittent, while ephemeral tributaries were subject to significant nexus analysis.25

15 Army Corps of Engineers and EPA, “Clean Water Rule: Definition of ‘Waters of the United States’; Final Rule,” 80
Federal Register 37054, June 29, 2015 (hereinafter “2015 Clean Water Rule”).
16 Ibid.
17 See EPA Web Archive at https://archive.epa.gov/epa/cleanwaterrule/what-clean-water-rule-does.html, which
includes a list of stakeholders requesting a rulemaking (https://archive.epa.gov/epa/sites/production/files/2014-03/
documents/wus_request_rulemaking.pdf).
18 2015 Clean Water Rule.
19 2015 Clean Water Rule, pp. 37056-37057.
20 2015 Clean Water Rule, p. 37057.
21 2015 Clean Water Rule, pp. 37058-37059.
22 2015 Clean Water Rule, pp. 37105-37106.
23 Ibid.
24 2015 Clean Water Rule, p. 37076.
25 2008 Guidance, pp. 6-8.
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Prior to 2015, waters and wetlands were jurisdictional if they were adjacent to certain regulated
waters. The 2015 Clean Water Rule confirmed that such adjacent waters are categorically
WOTUS and established numerical distance-based criteria to determine adjacency.26 The rule
defined adjacent to mean “bordering, contiguous, or neighboring” one of the aforementioned
waters, consistent with the 1986 Corps regulations.27 At the same time, the 2015 Clean Water
Rule newly defined neighboring by setting limits for the purposes of determining adjacency.28
Neighboring was defined to include waters (1) located within 100 feet of the ordinary high water
mark (OHWM)29 of a traditional navigable water, interstate water, the territorial seas,
jurisdictional tributary, or impoundment of these waters; (2) located in the 100-year floodplain
and within 1,500 feet of the OHWM of a traditional navigable water, interstate water, the
territorial seas, jurisdictional tributary, or impoundment of these waters; or (3) located within
1,500 feet of the high tide line of a traditional navigable water or the territorial seas and waters
located within 1,500 feet of the OHWM of the Great Lakes.30 (See Figure 1.) In addition, while
the pre-2015 rules included adjacent wetlands as a category of WOTUS, the 2015 Rule created a
new, broader category of WOTUS—adjacent waters—which included wetlands, ponds, lakes,
oxbows, impoundments, and similar features.31

26 2015 Clean Water Rule, p. 37105.
27 Ibid; 1986 Corps Rule, p. 41251.
28 2015 Clean Water Rule, p. 37058.
29 OHWM is defined in Corps and EPA regulations as “that line on the shore established by the fluctuations of water
and indicated by physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in the
character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that
consider the characteristics of the surrounding areas.”
30 2015 Clean Water Rule, p. 37105.
31 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774; 2015 Clean Water Rule, p. 37104. For more information on
these different water features, see U.S. EPA, Connectivity of Streams and Wetlands to Downstream Waters: A Review
and Synthesis of the Scientific Evidence, EPA/600/R-14/475F, Washington, DC, 2015, https://cfpub.epa.gov/si/
si_public_record_report.cfm?Lab=NCEA&dirEntryId=296414.
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Figure 1. Jurisdictional Waters Under the 2015 Clean Water Rule
Not drawn to scale

Source: Prepared by CRS, from Army Corps of Engineers and EPA, “Clean Water Rule: Definition of ‘Waters
of the United States’; Final Rule,” 80 Federal Register 37054, June 29, 2015.
Notes: “Jurisdictional by Rule” waters were jurisdictional per se without case-specific evaluation. “Tributaries”
and “adjacent waters” were jurisdictional by rule if they met the definitions established in the 2015 Clean Water
Rule. Waters requiring case-specific evaluation would have been jurisdictional if there was a significant nexus to
traditional navigable waters, interstate waters, or the territorial seas.
An OHWM is defined in Corps and EPA regulations as the line on the shore established by the fluctuations of
water and indicated by specific physical characteristics listed in those regulations (e.g., the natural line impressed
on the bank, the presence of litter and debris).
a. Case-specific evaluation for this subset of waters (waters within the 100-year floodplain, but beyond 1,500
feet from the OHWM) was limited to those waters within the 100-year floodplain of a traditional navigable
water, interstate water, or the territorial seas.
While the Corps and EPA contended that their primary intent in the 2015 Clean Water Rule was to
clarify (rather than enlarge) regulatory jurisdiction, some stakeholders and observers viewed it as
an expansion of CWA jurisdiction.32 Other stakeholders argued that it excluded too many waters
from federal jurisdiction.33 Following issuance of the 2015 Clean Water Rule, industry groups,
more than half the states, and several environmental groups filed lawsuits challenging the rule in
federal courts across the country.34 Some district courts issued preliminary injunctions
temporarily barring the 2015 Clean Water Rule from taking effect in certain states.35 Other courts

32 2015 Clean Water Rule, pp. 37055, 37083-37084. Also see, for example, Carolina Bolado, “Fla., Others Sue EPA,
Corps Over Clean Water Act Expansion,” Law360, June 30, 2015.
33 See, for example, 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.
34 For a discussion of the legal challenges to the 2015 Rule, see Army Corps of Engineers and EPA, “Definition of
‘Waters of the United States’—Recodification of Pre-Existing Rules,” 84 Federal Register 56626, 56628-30, October
22, 2019.
35 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);
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denied motions for preliminary injunctions.36 Separately, the U.S. Court of Appeals for the Sixth
Circuit issued a nationwide stay of the rule,37 although the nationwide stay was lifted after the
Supreme Court held that the Sixth Circuit lacked jurisdiction to hear challenges to the rule.38 Two
courts later remanded the 2015 Clean Water Rule to EPA and the Corps, concluding that it
violated the Administrative Procedure Act (APA) and exceeded the agencies’ statutory authority
under the CWA.39
At the time the Trump Administration rescinded the 2015 Clean Water Rule, as discussed below,
the rule was in effect in a patchwork of states that were not subject to a preliminary injunction or
one of the remand orders.
2020 Navigable Waters Protection Rule
The Trump Administration described the 2015 Clean Water Rule as an example of federal
“overreach” and took steps to rescind and revise it.40 On February 28, 2017, President Trump
issued an executive order directing the Corps and EPA to review and rescind or revise the 2015
Clean Water Rule and to consider interpreting the statutory term “navigable waters” in a manner
consistent with Justice Scalia’s opinion in Rapanos.41
The agencies responded to the executive order in a two-step process. In Step One, EPA and the
Corps rescinded the 2015 Clean Water Rule and recodified the pre-2015 regulations.42

Texas v. EPA, No. 3:15-cv-162, 2018 WL 4518230 (S.D. Tex. Sept. 12, 2018); Order, Or. Cattlemen’s Ass’n v. EPA,
No. 19-00564 (D. Or. July 26, 2019).
36 Ohio v. EPA, No. 2:15-cv-02467, 2019 WL 1368850 (S.D. Ohio Mar. 26, 2019); Oklahoma v. EPA, No. 4:15-cv-
00381, slip. op. at 11-12 (N.D. Okla. May 29, 2019). See also Order, Wash. Cattlemen’s Ass’n v. EPA, No. 2:19-cv-
00569 (W.D. Wash. Dec. 30, 2019) (denying preliminary injunction motion as moot after EPA and the Corps rescinded
the 2015 Rule).
37 In re EPA, 803 F.3d 804, 808 (6th Cir. 2015), vacated sub nom. In re U.S. Dep’t of Def., 713 F. App’x 489 (6th Cir.
2018).
38 Nat’l Ass’n of Mfrs. v. Dep’t of Def., 138 S. Ct. 617 (2018); In re U.S. Dep’t of Def., 713 F. App’x at 490.
39 Georgia v. Wheeler, 418 F. Supp. 3d 1336 (S.D. Ga. 2019); Texas v. EPA, 389 F. Supp. 3d 497 (S.D. Tex. 2019).
These two district courts struck down the 2015 Rule on a variety of legal grounds, including the inclusion of all
interstate waters in the definition of WOTUS, the use of the ordinary high-water mark and bed and banks in defining
tributaries that are considered WOTUS, the breadth of the definition of adjacent waters, the inclusion of a category of
waters that would be considered jurisdictional on a case-by-case basis if they met certain criteria, the rule’s intrusion
into traditional state powers, the inclusion of a farming exemption for adjacent waters but not tributaries, its use of the
100-year floodplain based on FEMA flood maps to define adjacent and case-by-case waters, and the 1,500-foot limit
for adjacent waters. Georgia v. Wheeler, 418 F. Supp. 3d at 1355-70, 1379-81. Both courts also found that the final
2015 Rule was not a “logical outgrowth” of the proposed rule, and thus violated the APA’s notice-and-comment
requirements for rulemaking. Id. at 1372-78; Texas v. EPA, 389 F. Supp. 3d at 503-06.
40 For example, EPA, “EPA, U.S. Army Repeal 2015 Rule Defining ‘Waters of the United States’ Ending Regulatory
Patchwork,” Sept. 12, 2019, https://www.epa.gov/newsreleases/epa-us-army-repeal-2015-rule-defining-waters-united-
states-ending-regulatory-patchwork.
41 Executive Order 13778, “Restoring the Rule of Law, Federalism, and Economic Growth by Reviewing the ‘Waters
of the United States’ Rule,” 82 Federal Register 12497, March 3, 2017. According to the Federal Register notice, the
executive order was issued on February 28, 2017.
42 Army Corps of Engineers and EPA, “Definition of ‘Waters of the United States’—Recodification of Pre-Existing
Rules,” 84 Federal Register 56626, October 22, 2019. Prior to issuance of the Step One Rule, EPA and the Corps
attempted to delay the implementation of the 2015 Rule for two years by adding an applicability date to that rule. Army
Corps of Engineers and EPA, “Definition of ‘Waters of the United States’—Addition of an Applicability Date to 2015
Clean Water Rule,” 82 Federal Register 55542, November 22, 2017. Two courts struck down the suspension of the
2015 Rule on the grounds that the agencies arbitrarily and capriciously failed to provide a meaningful opportunity for
public comment. S.C. Coastal Conservation League v. Pruitt, 318 F. Supp. 3d 959, 963 (D.S.C. 2018); Puget
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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.
On April 21, 2020, the Corps and EPA published a final Step Two Rule to redefine WOTUS,
titled the Navigable Waters Protection Rule.43 The rule went into effect on June 22, 2020,
replacing the Step One Rule. Although it was immediately challenged, the Navigable Waters
Protection Rule remained in effect in most jurisdictions until September 2021, when it was
vacated by a federal district court. This report nonetheless discusses the Navigable Waters
Protection Rule in some detail, because litigation is ongoing as of this writing, and because it is
important background against which the Biden Administration is expected to take new actions (as
described in more detail below).
Overall, the Navigable Waters Protection Rule narrowed the scope of waters and wetlands that
were considered WOTUS and therefore fell under federal jurisdiction compared to both the 2015
Clean Water Rule and the pre-2015 rules. The Navigable Waters Protection Rule was structured to
focus on relatively permanent bodies of water that provide surface flow to traditional navigable
waters or the territorial seas in a typical year.44 Thus, ephemeral features, including ephemeral
tributaries, were categorically excluded from WOTUS, as were features that did not provide
surface water flow in a typical year to certain jurisdictional waters.45 Also, although the
Navigable Waters Protection rule maintained tributaries and adjacent wetlands as categories of
WOTUS that were jurisdictional by rule, the rule narrowed the definitions of those two terms in
comparison to prior regulations.
Another of the rule’s overarching changes was its elimination of case-by-case significant nexus
determinations.46 The rule instead established four categories of waters that were categorically
WOTUS and specified which waters were categorically excluded.47 An overview of these
categories, including some of the changes from how such waters were considered under past
regulations, is discussed below.
In addition to these changes, the Navigable Waters Protection Rule removed interstate waters,
including interstate wetlands, as a separate category of WOTUS.48 The pre-2015 rules and the
2015 Clean Water Rule had each included interstate waters as a separate category of WOTUS.
Under the Navigable Waters Protection Rule, only those interstate waters that otherwise met the
criteria for one of the four WOTUS categories under the rule remained jurisdictional.49

Soundkeeper All. v. Wheeler, No. C15-1342, 2018 WL 6169196 (W.D. Wash. Nov. 26, 2018).
43 Army Corps of Engineers 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”).
44 Navigable Waters Protection Rule, pp. 22273-22274. The Navigable Waters Protection Rule defines the term typical
year to mean “when precipitation and other climatic variables are within the normal periodic range (e.g., seasonally,
annually) for the geographic area of the applicable aquatic resources based on a rolling thirty-year period.”
45 Navigable Waters Protection Rule, pp. 22251, 22279.
46 Navigable Waters Protection Rule, p. 22273.
47 Navigable Waters Protection Rule, p. 22251.
48 Navigable Waters Protection Rule, p. 22282.
49 Navigable Waters Protection Rule, p. 22283.
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Jurisdictional Categories and Implementation
Challenges
The precise categories the Corps and EPA have used to determine which waters are categorically
WOTUS and which are excluded have not always overlapped neatly from one rule to the next. A
full analysis of each regulatory framework’s scheme for categorizing waters as WOTUS or not
WOTUS is beyond the scope of this report. Instead, the following section uses the structure of the
Navigable Waters Protection Rule—the most recently promulgated regulation—to discuss how
the scope of included and excluded waters has changed, and for identification of selected
challenges the Biden Administration could face in developing and implementing a new definition
of WOTUS.
Waters That Are Categorically WOTUS
The Navigable Waters Protection Rule defined four categories of waters that were categorically
WOTUS.50
(1) Territorial Seas and Traditional Navigable Waters
Territorial seas and traditional navigable waters, which were jurisdictional by rule under the pre-
2015 rules and guidance as well as the 2015 Clean Water Rule, were included as separate
categories in those rules.51 The Navigable Waters Protection Rule included territorial seas and
traditional navigable waters as jurisdictional by rule, and it combined the two into one category
rather than separate categories in an effort to streamline and simplify the definition of WOTUS.52
The rule made no other substantive changes to these long-regulated categories of waters.53
(2) Tributaries
Tributaries were included as a category of WOTUS under the pre-2015 rules and guidance as well
as the 2015 Clean Water Rule, but the rules defined tributary differently. Under pre-2015
regulations, tributaries were jurisdictional by rule, but tributaries was not defined in regulation.54
Under the 2008 guidance, relatively permanent tributaries—which the agencies defined as
tributaries that flow year-round (i.e., perennial) or have continuous flow at least seasonally (i.e.,
intermittent)—were categorically WOTUS.55 Tributaries that were not relatively permanent (i.e.,
ephemeral) were subject to a case-by-case significant nexus analysis to determine jurisdiction.56
The 2015 Clean Water Rule newly provided a regulatory definition for tributaries. Under the 2015
Clean Water Rule, tributaries were jurisdictional by rule if they had certain features that were
indicators of flow (e.g., a bed and bank and an ordinary high water mark) and contributed flow

50 Navigable Waters Protection Rule, p. 22338.
51 2015 Clean Water Rule, p. 37104; 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774.
52 Navigable Waters Protection Rule, pp. 22338, 22281.
53 Ibid.
54 1986 Corps Rule, pp. 41250-41251; 1988 EPA Rule, p. 20774.
55 2008 Guidance, pp. 1, 6-7.
56 2008 Guidance, p. 8.
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directly or indirectly to a traditional navigable water, an interstate water, or the territorial seas.57
The tributary could be perennial, intermittent, or ephemeral as long as the criteria were met.
While the Navigable Waters Protection Rule included tributaries among waters that were
categorically WOTUS, the rule narrowed the definition of tributary in comparison to prior
regulations. Under the Navigable Waters Protection Rule, tributaries included rivers, streams, or
similar naturally occurring surface water channels that contributed surface water flow to a
territorial sea or traditional navigable water in a typical year.58 To be jurisdictional, the tributary
was required to be perennial or intermittent in a typical year.59 Ephemeral tributaries were
categorically not WOTUS.60 Thus, under the Navigable Waters Protection Rule, fewer tributaries
were considered WOTUS when compared to previous regulations and practice, when some
ephemeral waters were considered WOTUS.
(3) Lakes, Ponds, and Impoundments of Jurisdictional Waters
Impoundments of jurisdictional waters were jurisdictional by rule and included as a separate
category of WOTUS under both the pre-2015 rules and the 2015 Clean Water Rule.61 Lakes and
ponds were captured under other categories (e.g., traditional navigable waters, tributaries,
adjacent waters, or impoundments) in prior regulations.62
The Navigable Waters Protection Rule combined lakes, ponds, and impoundments of
jurisdictional waters into a single category of WOTUS.63 It also added flow or inundation
requirements to this category of WOTUS, which narrowed the scope of jurisdictional waters
compared to previous regulations and practice. Under the Navigable Waters Protection Rule, to be
considered WOTUS, lakes, ponds, and impoundments of jurisdictional waters were required to
either (1) contribute surface water flow in a typical year to a territorial sea or traditional navigable
water or (2) be inundated by flooding from a traditional navigable water, territorial sea,
jurisdictional tributary, or jurisdictional lake, pond, or impoundment in a typical year.64 The
flow/inundation requirements were a departure from past regulations and practice. The pre-2015
rules did not specify such requirements for impoundments of jurisdictional waters to be deemed
WOTUS.65 The preamble to the 2015 Clean Water Rule specified that impoundments of a
jurisdictional water were WOTUS regardless of flow or inundation requirements.66
(4) Adjacent Wetlands
Under pre-2015 rules, wetlands adjacent to jurisdictional waters were jurisdictional by rule.67 EPA
regulations did not define adjacent, but Corps regulations defined the term to mean “bordering,

57 2015 Clean Water Rule, pp. 37104-37106.
58 Navigable Waters Protection Rule, p. 22339.
59 Ibid.
60 Navigable Waters Protection Rule, p. 22338.
61 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774; 2015 Clean Water Rule, p. 37104.
62 Navigable Waters Protection Rule, pp. 22300-22301.
63 Navigable Waters Protection Rule, p. 22338.
64 Navigable Waters Protection Rule, pp. 22338-22339.
65 1986 Corps Rule, pp. 41250-21251; 1988 EPA Rule, p. 20774.
66 2015 Clean Water Rule, p. 37075.
67 1986 Corps Rule, p. 41250; 1988 EPA Rule, p. 20774.
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contiguous, or neighboring.”68 The Corps regulations also stated that “[w]etlands separated from
other waters of the United States by man-made dikes or barriers, natural river berms, beach dunes
and the like are ‘adjacent wetlands.’”69 The 2008 guidance further provided that adjacency was
established by (1) an unbroken surface or shallow subsurface connection to jurisdictional waters;
(2) physical separation from jurisdictional waters by man-made dikes or barriers, natural river
berms, beach dunes, or similar features; or (3) proximity to a jurisdictional water that supports an
inference of ecological interconnection.70 According to the 2008 guidance, wetlands that were
adjacent to traditional navigable waters and wetlands that abutted perennial or intermittent
tributaries to such waters were categorically WOTUS.71 Wetlands adjacent to ephemeral
tributaries and wetlands adjacent to perennial or intermittent tributaries that did not directly abut
them were subject to case-by-case significant nexus analysis to determine jurisdiction.72
Under the 2015 Clean Water Rule, as discussed above, the agencies similarly defined adjacent to
mean “bordering, contiguous, or neighboring” one of the aforementioned waters.73 However, the
2015 Clean Water Rule newly defined neighboring, which set new numeric standards for
determining adjacency.74 In addition, as discussed previously, the 2015 Clean Water Rule
broadened the category to adjacent waters—including wetlands, ponds, lakes, oxbows,
impoundments, and similar features.75
The Navigable Waters Protection Rule included adjacent wetlands as WOTUS, but it narrowed
the definition of what wetlands were considered adjacent compared to previous regulations and
practice. Specifically, it limited the definition of adjacent wetlands to include only those wetlands
that abutted or otherwise had a direct surface connection to other jurisdictional waters in a typical
year, rather than allowing for a shallow subsurface connection or ecological interconnection to
such waters. Under the Navigable Waters Protection Rule, adjacent wetlands included 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.76
Waters and Features That Are Not WOTUS
Some waters or water features have been excluded from WOTUS in similar form in pre-2015
practice, the 2015 Clean Water Rule, and the Navigable Waters Protection Rule. While some of
these exclusions were not listed in the pre-2015 rules, they were regularly applied in practice and

68 1986 Corps Rule, p. 41251.
69 Ibid.
70 2008 Guidance, pp. 5-6.
71 2008 Guidance, p. 1.
72 Ibid.
73 2015 Clean Water Rule, p. 37105.
74 Ibid.
75 2015 Clean Water Rule, p. 37104.
76 Navigable Waters Protection Rule, p. 22338.
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then specifically added to the 2015 Clean Water Rule and Navigable Waters Protection Rule for
clarity:77
 groundwater, including groundwater drained through subsurface drainage
systems;
 artificially irrigated areas that would revert to upland, or dry land, if artificial
irrigation ceased; 78
 artificial lakes and ponds that are not jurisdictional impoundments and that are
constructed or excavated in upland, or dry land; 79
 water-filled depressions constructed or excavated in upland, or dry land,
incidental to mining or construction activity, and pits excavated in upland for the
purpose of obtaining fill, sand, or gravel;80
 stormwater control features constructed or excavated in upland, or dry land, to
convey, treat, infiltrate, or store stormwater runoff;81
 groundwater recharge, water reuse, and wastewater recycling structures
constructed or excavated in upland, or dry land;82 and
 waste treatment systems.83
The scope of some other excluded categories has changed over time, however. First, the 2015
Clean Water Rule (and pre-2015 practice) regulated ditches that met the definition of tributary
and that were constructed in or relocated a tributary, and excluded other ditches.84 The Navigable
Waters Protection Rule considered ditches in a manner similar to previous regulations, but with a
narrower scope. Ditches that were traditional navigable waters, or ditches that were constructed in
or that relocated a tributary, or were constructed in an adjacent wetland as long as the ditch
satisfied the flow conditions of the tributary definition, were all considered WOTUS.85 Any

77 Some of the precise wording for these exclusions varies from rule to rule. Where there are differences, phrasing from
the Navigable Waters Protection Rule was included, as it is the most recently promulgated rule.
78 The Corps and EPA newly defined upland in the Navigable Waters Protection Rule in an aim to improve regulatory
predictability and clarity. The rule defined upland as any land area above the ordinary high water mark or high tide line
that does not satisfy all three wetland factors under normal circumstances, as described in the Corps 1987 Wetlands
Delineation Manual. Navigable Waters Protection Rule, pp. 22252, 22341. The 2015 Clean Water Rule used the term
dry land, while the pre-2015 rules used the term upland.
79 The Navigable Waters Protection Rule also provided that this exclusion applied to artificial lakes and ponds that are
constructed or excavated in nonjurisdictional waters. Navigable Waters Protection Rule, p. 22340.
80 The Navigable Waters Protection Rule also provided that this exclusion applied to water-filled depressions
constructed or excavated in nonjurisdictional waters for the purposes listed. Ibid.
81 The Navigable Waters Protection Rule also provided that this exclusion applied to stormwater control features
constructed or excavated in nonjurisdictional waters. Ibid.
82 The Navigable Waters Protection Rule also provided that this exclusion applied to such structures constructed or
excavated in nonjurisdictional waters. Ibid.
83 The Corps and EPA newly defined waste treatment system in the Navigable Waters Protection Rule in an aim to
improve regulatory predictability and clarity. The rule defined waste treatment system to include “all components,
including lagoons and treatment ponds (such as settling or cooling ponds), designed to either convey or retain,
concentrate, settle, reduce, or remove pollutants, either actively or passively, from wastewater prior to discharge (or
eliminating any such discharge).” Navigable Waters Protection Rule, p. 22341.
84 2015 Clean Water Rule, pp. 37058, 37105. The 2015 Rule also regulated ditches with intermittent flow that drain
wetlands—something not specified in the Navigable Water Protection Rule.
85 Navigable Waters Protection Rule, pp. 22295, 22338.
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ditches that did not meet these criteria were excluded from WOTUS.86 Because the definition of
tributary under the Navigable Waters Protection Rule was narrower than the 2015 Clean Water
Rule’s definition, however, fewer ditches were considered WOTUS under the Navigable Waters
Protection Rule.
Second, while all three regulatory frameworks have excluded prior converted cropland, the scope
of the term has changed over time. Corps and EPA regulations have excluded prior converted
cropland since 1993, and the 2015 Clean Water Rule maintained the exclusion.87 The preamble to
the 1993 rule which added the exclusion to regulations included criteria for determining when
prior converted cropland was considered abandoned and the exclusion ceased to apply.88
Specifically, the 1993 rule’s abandonment criteria required that an area be used for production of
an agricultural commodity.89 The Navigable Waters Protection Rule retained the long-standing
exclusion for prior converted cropland, but defined the term in regulations for the first time. The
rule clarified the abandonment criteria and specified that an area would cease to be considered
prior converted cropland for CWA purposes when both the prior converted cropland “is not used
for, or in support of, agricultural purposes at least once in the immediately preceding five years”
and the land reverts to wetland status, as defined in the rule.90 The term agricultural purposes was
not defined by regulation, but some text in the preamble appeared to broaden the prior converted
cropland exception for CWA purposes.
Additionally, the Navigable Waters Protection Rule added three new excluded categories:
ephemeral features, diffuse stormwater runoff and directional sheet flow over upland, and waters
not identified as categorically WOTUS.91 As previously discussed, the Navigable Waters
Protection Rule specified that ephemeral features, including ephemeral streams, swales, gullies,
rills, and pools, were not WOTUS.92 However, it clarified that a tributary, lake, pond, or
impoundment of a jurisdictional water did not lose its jurisdictional status if it contributed surface
water flow to a downstream jurisdictional water in a typical year through a channelized
ephemeral feature.93 In contrast, if an upstream water was connected to the downstream
jurisdictional water only by diffuse stormwater runoff or directional sheet flow over upland, the
upstream water was not jurisdictional under the Navigable Waters Protection Rule.94 More
broadly, the Navigable Waters Protection Rule added an exclusion for waters not identified as

86 Ibid.
87 Army Corps of Engineers and EPA, “Clean Water Act Regulatory Programs,” 58 Federal Register 45008, August
25, 1993 (hereinafter “1993 Rule”); 2015 Clean Water Rule, pp. 37059, 37096. For a more in-depth discussion about
the prior converted cropland exclusion under the Clean Water Act, see CRS In Focus IF11136, Prior Converted
Cropland Under the Clean Water Act, by Laura Gatz and Megan Stubbs. Both CWA regulations and Food Security Act
regulations include exceptions to their requirements for prior converted cropland. The Food Security Act of 1985—
enacted on December 23, 1985—included a wetland conservation provision (“Swampbuster”) which indirectly protects
wetlands by making producers who farm or convert wetlands to agricultural production ineligible for select federal
farm program benefits. While historically the agencies defined prior converted cropland similarly, the way the
agencies have determined what qualifies as prior converted cropland has diverged over time.
88 1993 Rule, p. 45034.
89 Ibid.
90 Navigable Waters Protection Rule, p. 22320.
91 The Navigable Waters Protection Rule defined upland as “any land area that under normal circumstances does not
satisfy all three wetland factors … and does not lie below the ordinary high water mark or the high tide line of a
jurisdictional water.” Navigable Waters Protection Rule, p. 22339.
92 Navigable Waters Protection Rule, p. 22338.
93 Navigable Waters Protection Rule, pp. 22306, 22319, 22338-22339.
94 Navigable Waters Protection Rule, pp. 22278, 22319.
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categorically WOTUS, thereby eliminating the category of waters subject to significant nexus
analysis.
Implementation Challenges
In promulgating the Navigable Waters Protection Rule, the agencies pointed to its potential
benefits in increased certainty over the Clean Water Rule and the pre-2015 regulations. The
Navigable Waters Protection Rule, for instance, would have simplified most jurisdictional
determinations and eliminated the fact-specific “significant nexus” standard which applied after
Rapanos. Observers, however, claimed that these changes did not necessarily eliminate
uncertainty, but only shifted it to new areas. The Navigable Waters Protection Rule depended
upon new definitions or different applications for concepts such as typical year, perennial,
intermittent, and ephemeral. Some observers argued that applying these terms to jurisdictional
determinations (i.e., determinations as to whether particular water bodies are WOTUS) could be
difficult. In addition, some observers argued that the removal of interstate waters as its own
category of WOTUS could lead to implementation challenges.
“Typical Year”
The Navigable Waters Protection Rule defined the term typical year to mean “when precipitation
and other climatic variables are within the normal periodic range (e.g., seasonally, annually) for
the geographic area of the applicable aquatic resources based on a rolling thirty-year period.” In
the preamble to the rule, the agencies stated that under the final definition, “a typical year would
generally not include times of drought or extreme flooding.”95
Some stakeholders, including scientists and environmental groups, argued that the typical year
approach to the rule was concerning in light of climate change.96 In their comments on the
proposed rule, a coalition of scientific groups argued that the typical year approach “ignores the
periodic and substantial connectivity that occurs during increasingly frequent atypical years
resulting from climate change.”97 Some stakeholders also argued that it was unclear how a
jurisdictional determination would be made if agencies were making such a determination when
conditions did not reflect a typical year (either too wet or dry).98 Further, some observed that a
water body transitioning between protected and unprotected status in response to weather was not
consistent with the agencies’ stated objective to provide clarity and predictability through the new
rule.99

95 Navigable Waters Protection Rule, p. 22274. The agencies consider a year to be typical when the rainfall from the
previous three months falls within the 30th and 70th percentiles established by a 30-year average generated at NOAA
weather stations. Ibid.
96 Corps and EPA, The Navigable Waters Protection Rule—Public Comment Summary Document, Topic 9: Typical
Year, April 21, 2020, p. 11, https://www.regulations.gov/document/EPA-HQ-OW-2018-0149-11574.
97 Letter from American Fisheries Society, American Institute of Biological Sciences, and Association for the Sciences
of Limnology and Oceanography, et al. to Andrew Wheeler, EPA Administrator and R.D. James, Assistant Secretary of
the Army for Civil Works, April 10, 2019, EPA Docket ID No. EPA-HQ-OW-2018-0149.
98 Corps and EPA, The Navigable Waters Protection Rule—Public Comment Summary Document, Topic 9: Typical
Year, April 21, 2020, p. 17, https://www.regulations.gov/document/EPA-HQ-OW-2018-0149-11574.
99 See, for example Adam S. Ward and Riley Walsh, “New Clean Water Act Rule Leaves U.S. Waters Vulnerable,”
American Geophysical Union News, February 11, 2020, pp. https://eos.org/opinions/new-clean-water-act-rule-leaves-u-
s-waters-vulnerable. See also Corps and EPA, The Navigable Waters Protection Rule—Public Comment Summary
Document, Topic 11: Economic Analysis and Resource and Programmatic Assessment, April 21, 2020, p. 42,
https://www.regulations.gov/document/EPA-HQ-OW-2018-0149-11574.
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As they had done under both the pre-2015 rules and the Clean Water Rule, the Corps and EPA
signaled that they would rely in part on guidance beyond the text of the rule itself to guide
implementation. Concurrent with the issuance of the Navigable Waters Protection Rule, the Corps
and EPA published a fact sheet specific to the typical year concept.100 Responding to some
stakeholder concerns, the agencies stated that using data from a shorter-than-30-year period could
“potentially exaggerate the effects of short-term trends of drought or excessively rainy
periods.”101 They also noted that during atypically wet or dry periods, it might be necessary to
rely more heavily on data collected during “typical year” conditions, such as aerial photography
or remote sensing imagery.102
Differentiating Between Intermittent and Ephemeral
In the Navigable Waters Protection Rule, the Corps and EPA indicated that they included
definitions of the terms perennial, intermittent, and ephemeral to ensure clarity.103 The agencies
defined perennial as surface water flowing continuously year-round; intermittent as flowing
continuously during certain times of the year and more than in direct response to precipitation
(e.g., seasonally when the groundwater table is elevated or when snowpack melts); and ephemeral
as flowing or pooling only in direct response to precipitation (e.g., rain or snowfall).104 However,
some stakeholders expressed concerns regarding the challenges in differentiating between these
concepts.
Some commenters on the proposed rule requested further clarification on the distinction between
intermittent and ephemeral, noting concerns about various scenarios that could make the
difference less certain. For example, some commenters requested clarification regarding whether
streams that flow continuously during a rainy season, such as monsoon-driven streams, are
considered intermittent. Others requested additional clarification on how to distinguish between
melting snowfall (which under the rule could be considered ephemeral flow) versus melting
snowpack (which could be considered the source of perennial or intermittent flow).105 Some city
and county stakeholders also noted that, in some parts of the country, the terms can be used
interchangeably, especially in areas that experience a lot of rain.106
Concurrent with the issuance of the Navigable Waters Protection Rule, the Corps and EPA
published a fact sheet focused on implementing the Navigable Waters Protection Rule.107 In the
fact sheet, the agencies discussed some of best available sources of information that could be used
to determine flow classification and jurisdiction.

100 Corps and EPA, “Typical Year” and the Navigable Waters Protection Rule Factsheet, 2020, https://www.epa.gov/
sites/production/files/2020-01/documents/nwpr_fact_sheet_-_typical_year.pdf.
101 Ibid.
102 Ibid.
103 Navigable Waters Protection Rule, p. 22275.
104 Navigable Waters Protection Rule, p. 22338.
105 Navigable Waters Protection Rule, p. 22276.
106 Comment Letter from National Association of Counties, National League of Cities, and the United States
Conference of Mayors to EPA and the Corps, “Re: Proposed Rule on the ‘Revised Definition of ‘Waters of the United
States,’ Docket No. EPA-HQ-OW-2018-0149,” April 15, 2019, https://downloads.regulations.gov/EPA-HQ-OW-2018-
0149-4629/attachment_1.pdf.
107 Corps and EPA, Implementing the Navigable Waters Protection Rule Factsheet, 2020, https://www.epa.gov/sites/
production/files/2020-01/documents/nwpr_fact_sheet_-_implementation_tools.pdf.
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Interstate Waters
Stakeholders also expressed concerns about changes in the Navigable Waters Protection Rule
regarding interstate waters. The Navigable Waters Protection Rule removed interstate waters,
including interstate wetlands, as a separate category of WOTUS.108 Although prior regulations—
both the pre-2015 rules and the 2015 Clean Water Rule—included interstate waters as a separate
category of WOTUS, the Corps and EPA asserted that “interstate waters without any surface
water connection to traditional navigable waters or the territorial seas are not within the agencies’
authority under the CWA.”109 The agencies nonetheless stated that any interstate waters that
otherwise met the criteria for one of the four WOTUS categories under the rule would remain
jurisdictional. While some stakeholders supported this change, others expressed concern that loss
of interstate management of waters by federal agencies that no longer qualified as WOTUS could
lead to complex interstate issues.110 Specifically, some expressed concerns about resolving
conflicts without federal assistance, as well as concerns about pollutants that could come from
upstream waters.111
Stakeholder Reponses and Litigation Regarding the
Navigable Waters Protection Rule
The promulgation of the Navigable Waters Protection Rule prompted a range of reactions from a
variety of stakeholders.
Industrial and agricultural groups that supported the Navigable Waters Protection Rule asserted,
among other things, that it provided greater certainty and clarity and scaled back federal
jurisdiction from the “significant expansion” under the 2015 Clean Water Rule to a more
appropriate scope.112 Some of these groups, in comments filed in favor of the proposed Navigable
Waters Protection Rule, explained that while they supported the rule, they also believed the
agencies should further narrow jurisdiction by, for example, limiting how they define a traditional

108 Navigable Waters Protection Rule, pp. 22282-22283.
109 Navigable Waters Protection Rule, p. 22284.
110 Corps and EPA, The Navigable Waters Protection Rule - Public Comment Summary Document, Topic 3: Interstate
Waters, April 21, 2020, https://www.regulations.gov/document/EPA-HQ-OW-2018-0149-11574. See also ASWM
Insights, p. 4, https://www.aswm.org/pdf_lib/aswm_initial_insights_on_final_wotus_rule.pdf.
111 Association of State Wetland Managers, “The Navigable Waters Protection Rule: Highlights & Initial Take-Aways:
Needs and Gaps Identified by State and Tribal Wetland Programs,” slide presentation, March 25, 2020,
https://www.aswm.org/pdf_lib/member_webinar/navigable_waters_protection_rule_032520_zollitsch.pdf.
112 See, for example, National Association of Home Builders, 2020 Definition of Waters of the United States, March
2020, https://www.nahb.org/-/media/NAHB/advocacy/docs/industry-issues/waters-of-the-us/wotus-analysis-2020.pdf.
National Mining Association, Clean Water Regulation That’s Clear, April 1, 2020, https://nma.org/wp-content/
uploads/2019/03/2020-WOTUS.pdf. Agricultural Retailers Association, “ARA Supports Navigable Waters Protection
Rule’s Publishing,” press release, April 21, 2020, https://www.aradc.org/news/ara-supports-navigable-waters-
protection-rules-publishing. American Farm Bureau Federation, “New Clean Water Rule Provides Clarity, Certainty to
Farmers and Ranchers,” press release, January 23, 2020, https://www.fb.org/newsroom/new-clean-water-rule-provides-
clarity-certainty-to-farmers-and-ranchers.
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navigable water.113 Some states also supported the rule, asserting that they are most
knowledgeable about their waters and are in the best position to manage them effectively.114
Other stakeholders, including environmental groups and some states, voiced strong opposition to
the Navigable Waters Protection Rule. Some of these stakeholders expressed concern that the rule
would “roll back” protections on many waters and could have a broad impact on water quality.115
Some states asserted, among other things, that the rule would result in loss of protection in some
areas and uneven protections across states.116 Some further asserted that the changes could make
it more challenging for some states to address pollution from upstream jurisdictions.117 Some also
argued that the interconnectedness of water necessitates a minimum federal standard for most
waters rather than a patchwork approach.118 From a different perspective, some ranching groups
opposed the Navigable Waters Protection Rule, arguing that the Corps and EPA defined navigable
waters too broadly.119
EPA Science Advisory Board Commentary
In February 2020, EPA’s Science Advisory Board (SAB), a federal advisory committee which
was created in 1978 to provide scientific advice to EPA, finalized and transmitted a commentary
on the proposed revised definition of WOTUS.120 The SAB had previously weighed in on the
science of CWA jurisdiction in 2014. Specifically, the SAB conducted a technical review of a
report prepared by EPA’s Office of Research and Development synthesizing the peer-reviewed
science on the relationship and downstream effects of waters (often referred to as the
“Connectivity Report”), which provided much of the technical basis for the 2015 Clean Water

113 See, for example, Letter from Gregory Ugalde, Chairman of the Board, National Association of Home Builders, to
Andrew Wheeler, EPA Administrator, April 15, 2019, Docket ID No. EPA-HQ-OW-2018-0149. Letter from Katie
Sweeney, General Counsel, National Mining Association, to EPA, April 15, 2019, https://www.regulations.gov/
document?D=EPA-HQ-OW-2018-0149-0003.
114 See, for example, Arizona Department of Environmental Quality, “Waters of the United States (WOTUS),” press
release, 2020, https://azdeq.gov/wotus. North Dakota Office of the Governor, “Burgum welcomes clarity of Navigable
Waters Protection Rule for farmers, landowners,” press release, January 23, 2020, https://www.governor.nd.gov/news/
burgum-welcomes-clarity-navigable-waters-protection-rule-farmers-landowners.
115 See, for example, Waterkeeper Alliance, ‘Navigable Water Protection Rule’ Guarantees Widespread Pollution of
our Nation’s Waters, February 13, 2020, https://waterkeeper.org/news/navigable-water-protection-rule-guarantees-
widespread-pollution-of-our-nations-waters/. See also Letter from New Jersey State Legislature Members to Andrew
Wheeler, EPA Administrator and R.D. James, Assistant Secretary of the Army for Civil Works, March 2019,
https://downloads.regulations.gov/EPA-HQ-OW-2018-0149-9890/attachment_1.pdf.
116 See, for example, Letter from Kate Brown, Governor, State of Oregon, to Andrew Wheeler, EPA Administrator and
R.D. James, Assistant Secretary of the Army for Civil Works, April 11, 2019, https://downloads.regulations.gov/EPA-
HQ-OW-2018-0149-5412/attachment_1.pdf.
117 See, for example, Letter from Ben Grumbles, Secretary, Maryland Department of the Environment, to Andrew
Wheeler, EPA Administrator and R.D. James, Assistant Secretary of the Army for Civil Works, April 15, 2019,
https://downloads.regulations.gov/EPA-HQ-OW-2018-0149-4901/attachment_1.pdf.
118 “Coalition of 17 state AGs joins challenges to 2020 WOTUS rule,” InsideEPA, May 1, 2020, https://insideepa.com/
daily-feed/coalition-17-state-ags-joins-challenges-2020-wotus-rule.
119 Pacific Legal Foundation, “EPA’s new navigable waters rule challenged,” press release, April 27, 2020,
https://pacificlegal.org/press-release/epas-new-navigable-waters-rule-challenged/.
120 Dr. Michael Honeycutt, Chair, Commentary on the Proposed Rule Defining the Scope of Waters Federally
Regulated Under the Clean Water Act, EPA Science Advisory Board, EPA-SAB-20-002, February 27, 2020,
https://yosemite.epa.gov/sab/sabproduct.nsf/LookupWebReportsLastMonthBOARD/
729C61F75763B8878525851F00632D1C/$File/EPA-SAB-20-002+.pdf (hereinafter “SAB commentary”). See EPA,
“About the Science Advisory Board,” https://sab.epa.gov/ords/sab/f?p=100:2:15698006221959 (last visited Sept. 3,
2021).
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Rule.121 The SAB also reviewed the adequacy of the scientific and technical basis of the proposal
for the Clean Water Rule. In providing comments on the Navigable Waters Protection Rule, the
SAB thus opted to provide a “commentary” on the rule because the science had not changed, but
the agencies’ position on how to use the science to inform its policy decision had changed.122 The
SAB found that the proposed Navigable Waters Protection Rule “decreases protection for our
Nation’s waters” and concluded that it “does not incorporate best available science and as such
we find that a scientific basis for the proposed Rule, and its consistency with the objectives of the
Clean Water Act, is lacking.”123 The SAB highlighted several concerns about certain types of
waters excluded from the definition of WOTUS in the proposed rule, as well as the basis for
adopting a surface-water-based definition of WOTUS.124 The SAB summarized these concerns by
stating that the “current scientific understanding of surface and ground water … is not reflected in
the proposed Rule. Specifically, the proposed definition of WOTUS excludes ground water,
ephemeral streams, and wetlands which connect to navigable waters below the surface.”125 The
SAB further stated that the agencies did not present new science to support the new definition,
and therefore the proposed rule “lacks a scientific justification, while potentially introducing new
risks to human and environmental health.”126
Litigation and the Biden Administration’s Actions
States, environmental groups, tribes, and other stakeholders challenged the Navigable Waters
Protection Rule in many separate cases.127 On June 19, 2020, the U.S. District Court for the
District of Colorado issued a preliminary injunction which barred the implementation of the
Navigable Waters Protection Rule only in the state of Colorado.128 However, on March 2, 2021,
the U.S. Court of Appeals for the Tenth Circuit reversed and vacated the district court’s decision,
lifting the injunction and allowing the rule to take effect in Colorado.129

121 U.S. EPA, Connectivity of Streams and Wetlands to Downstream Waters: A Review and Synthesis of the Scientific
Evidence, EPA/600/R-14/475F, Washington, DC, 2015, https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=
NCEA&dirEntryId=296414.
122 SAB Commentary, pp. 1-2.
123 SAB Commentary, p. 1.
124 SAB Commentary, pp. 2-3.
125 SAB Commentary, p. 4.
126 SAB Commentary, p. 4.
127 Complaint, Pueblo of Laguna v. Regan, No. 1:21-cv-277, Doc. No. 1 (D.N.M. March 26, 2021); Amended
Complaint, Waterkeeper Alliance, Inc. v. Wheeler, No. 3:18-cv-3521, Doc. No. 93 (N.D. Cal. Dec. 23, 2020);
Complaint, Env’t Integrity Project v. Wheeler, No. 1:20-cv-1734, Doc. No. 1 (D.D.C. June 25, 2020); Complaint,
Pasqua Yaqui Tribe v. EPA, No. 4:20-cv-266, Doc. No. 1 (D. Ariz. June 22, 2020); Complaint, Puget Soundkeeper
Alliance v. EPA, No. 2:20-cv-950, Doc. No. 1 (W.D. Wash. June 22, 2020); Motion for Preliminary Injunction, N.M.
Cattle Growers’ Ass’n v. EPA, No. 1:19-cv-00988, Doc. No. 30 (D.N.M. May 26, 2020); Complaint, Colorado v. EPA,
No. 1:20-cv-1461, Doc. No. 1 (D. Colo. May 22, 2020); Complaint, Navajo Nation v. Wheeler, No. 2:20-cv-602, Doc.
No. 1 (D.N.M. June 22, 2020); Amended Complaint, Murray v. Wheeler, No. 1:19-cv-1498, Doc. No. 17 (N.D.N.Y.
May 11, 2020); Second Supplemental Complaint, Wash. Cattlemen’s Ass’n v. EPA, No. 2:19-cv-00569, Doc. No. 72
(May 4, 2020); Complaint, California v. Wheeler, No. 3:20-cv-03005, Doc. No. 1 (N.D. Cal. May 1, 2020); First
Supplemental Complaint, Or. Cattlemen’s Ass’n v. EPA, No. 3:19-cv-00564, Doc. No. 90 (D. Or. May 1, 2020);
Complaint, Conservation Law Found. v. EPA, No. 20-cv-10820, Doc. No. 1 (D. Mass. April 29, 2020); Complaint,
Chesapeake Bay Found., Inc. v. Wheeler, No. 1:20-cv-1063, Doc. No. 1 (D. Md. April 29, 2020); Complaint, S.C.
Coastal Conservation League v. Wheeler, No. 2:20-cv-1687, Doc. No. 1 (D.S.C. April 29, 2020).
128 Colorado v. EPA, 445 F. Sup. 3d 1295 (D. Colo. 2020).
129 Colorado v. EPA, 989 F.3d 874 (10th Cir. 2021).
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To date, courts have not ruled on the merits of the Navigable Waters Protection Rule. However,
developments during the Biden Administration have made the legal status of the rule uncertain,
and it is not currently being applied anywhere in the country.
President Biden signaled interest in reconsidering the Navigable Waters Protection Rule
immediately upon taking office. On January 20, 2021, President Biden issued an executive order
(E.O. 13990) which revoked the Trump Administration’s executive order directing the Corps and
EPA to review and rescind or revise the Clean Water Rule.130 Although the Biden
Administration’s executive order did not itself rescind the Trump Administration’s Navigable
Waters Protection Rule, it also directed the heads of all agencies to “immediately review all
existing regulations, orders, guidance documents, policies, and any other similar agency actions
(agency actions) promulgated, issued, or adopted” during the Trump Administration “that are or
may be inconsistent with, or present obstacles to, the policy set forth” in the order.131 The
executive order further stated “for any such actions identified by the agencies, the heads of
agencies shall, as appropriate and consistent with applicable law, consider suspending, revising,
or rescinding the agency actions.”132 In conjunction with the executive order, the Biden
Administration included the Navigable Waters Protection Rule in a fact sheet listing more than
100 agency actions that heads of agencies were to review in accordance with the executive
order.133
In addition, on January 21, 2021, EPA sent a letter to the U.S. Department of Justice (DOJ)
requesting that DOJ seek stays for pending litigation involving judicial review of EPA regulations
issued during the Trump Administration.134 In a number of cases, courts granted requests to stay
challenges to the Navigable Waters Protection Rule while EPA reviewed the rule.135
Also, in March 2021, EPA’s Office of Inspector General published a report, with findings from a
year-long performance audit, concluding that EPA failed to adhere to certain aspects of its internal
process in promulgating selected rulemakings, including the Navigable Waters Protection Rule.136
On June 9, 2021, the Corps and EPA announced their intent to revise the definition of WOTUS.137
After reviewing the Navigable Waters Protection Rule pursuant to Executive Order 13990, the
agencies “determined that the rule is significantly reducing clean water protections.” For
example, the agencies’ review found “numerous clear and consistent indicators of a substantial

130 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.
131 Ibid, p. 7037.
132 Ibid.
133 The White House, “Fact Sheet: List of Agency Actions for Review,” press release, January 20, 2021,
https://www.whitehouse.gov/briefing-room/statements-releases/2021/01/20/fact-sheet-list-of-agency-actions-for-
review/.
134 Letter from Melissa A. Hoffer, Acting General Counsel, U.S. EPA Office of General Counsel, to Jean E. Williams
and Bruce S. Gelber, Deputy Assistant Attorneys General, Environment and Natural Resources Division, U.S.
Department of Justice, January 21, 2021.
135 See Joint Notice Regarding the Status of Pending Litigation in Other Jurisdictions, Conservation Law Found. v.
EPA, No. 20-cv-10820, Doc. No. 107 (May 14, 2021) (summarizing the status of litigation challenging the Navigable
Waters Protection Rule as of May 14, 2021).
136 U.S. EPA Office of Inspector General, EPA Does Not Always Adhere to Its Established Action Development
Process for Rulemaking, Report No. 21-P-0115, March 31, 2021, https://www.epa.gov/sites/default/files/2021-03/
documents/_epoig_20210331-21-p-0115.pdf.
137 EPA, “EPA, Army Announce Intent to Revise Definition of WOTUS,” press release, June 9, 2021, at
https://www.epa.gov/newsreleases/epa-army-announce-intent-revise-definition-wotus (hereinafter “June 2021 Press
Release”).
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reduction in waters covered under the [Navigable Waters Protection Rule] compared to previous
rules and practice.” Of particular concern to the agencies was the disproportionate impact in arid
states. Corps data showed that in New Mexico and Arizona, almost all of the 1,538 streams
assessed since the Navigable Waters Protection Rule went into effect were found to be
nonjurisdictional.138 The agencies also noted that at least 333 projects that formerly required CWA
Section 404 permits do not require them under the Navigable Waters Protection Rule.139
Accordingly, in their June 9 announcement, the agencies indicated that they (1) planned to initiate
a new rulemaking process to restore the regulatory landscape as it existed prior to implementation
of the 2015 Clean Water Rule; and (2) anticipated developing a new rule to define WOTUS
through a process that would be informed by stakeholder engagement and the experience of
implementing prior rules.140
In conjunction with their June 9 announcement, the Corps and EPA began asking courts to
remand the Navigable Waters Protection Rule while the agencies develop a new regulation.141 The
agencies argued that remand is appropriate to avoid potentially unnecessary litigation over
aspects of the Navigable Waters Protection Rule that may change when WOTUS is redefined.142
The agencies sought remand without vacatur, meaning that the Navigable Waters Protection Rule
would remain in effect pending the development of a new rule if their motions were granted.143
Some groups opposed this aspect of the agencies’ motion, arguing that courts should vacate the
Navigable Waters Protection Rule if they grant the remand request.144 Each case is proceeding on
a separate timeline. Some courts have granted the Corps and EPA’s motion, remanding the rule
but not vacating it.145
On August 30, 2021, the U.S. District Court for the District of Arizona granted the agencies’
request for voluntary remand in Pasqua Yaqui Tribe v. EPA, but it also vacated the rule.146 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 “involve

138 Department of the Army and EPA, Memorandum for the Record: Review of U.S. Army Corps of Engineers ORM2
Permit and Jurisdictional Determination Data to Assess Effects of the Navigable Waters Protection Rule, June 8, 2021,
https://www.epa.gov/sites/default/files/2021-06/documents/
3_final_memorandum_for_record_on_review_of_data_web_508c.pdf.
139 Ibid.
140 June 2021 Press Release.
141 E.g., Motion for Remand Without Vacatur, Conservation Law Found. v. EPA, No. 1:20-cv-10820, Doc. No. 112 (D.
Mass. June 6, 2021).
142 Id. at 1.
143 E.g., Memorandum of Law in Support of Motion for Voluntary Remand Without Vacatur, Conservation Law
Found. v. EPA, No. 1:20-cv-10820, Doc. No. 113, at 9 (D. Mass. June 9, 2021).
144 E.g., Response in Partial Opposition to Defendants’ Motion for Remand Without Vacatur, Conservation Law Found.
v. EPA, No. 1:20-cv-10820, Doc. No. 115 (D. Mass. June 23, 2021).
145 Order, S.C. Coastal Conservation League v. Regan, No. 2:20-cv-1687, Doc. No. 147 (D.S.C. July 15, 2021); Order,
Conservation Law Found. v. EPA, No. 1:20-cv-10820, Doc. No. 122 (D. Mass. Sept. 1, 2021); Order, Murray v. Regan,
No. 1:19-cv-01498, Doc. No. 46 (N.D.N.Y. Sept. 7, 2021); Order Granting Motion to Remand, California v. Regan,
No. 3:20-cv-03005, Doc. No. 271 (N.D. Cal. Sept. 16, 2021); Order Granting Motion to Remand, Waterkeeper
Alliance, Inc. v. EPA, No. 18-cv-03521, Doc. No. 125 (N.D. Cal. Sept. 16, 2021); Memorandum Opinion and Order
Granting Motion to Remand and Finding Vacatur Issue Now Moot, Pueblo of Laguna v. Regan, No. 1:21-cv-00277,
Doc. No. 40 (D.N.M. Sept. 21, 2021).
146 Order, Pasqua Yaqui Tribe v. EPA, No. 4:20-cv-00266, Doc. No. 99 (D. Ariz. Aug. 30, 2021). The court did not
address the plaintiffs’ pending challenges to the Trump Administration’s 2019 rule repealing the 2015 Clean Water
Rule, but indicated that it would order further proceedings regarding to resolve that portion of the litigation. Id. at 10-
11. Although the caption refers to the tribe as the “Pasqua Yaqui Tribe,” the correct spelling is “Pascua Yaqui.”
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fundamental, substantive flaws that cannot be cured without revising or replacing the [rule’s]
definition of [WOTUS].”147 Additionally, the court found that remanding without vacatur “would
risk serious environmental harm” in light of the reduction in waters considered to be WOTUS.148
The court also found that vacatur and a return to the pre-2015 regulatory regime would not result
in an unacceptable level of regulatory uncertainty.
The district court’s order did not specify what would take the place of the Navigable Waters
Protection Rule following vacatur, nor did it specify whether the vacatur of the rule would apply
nationwide or only in Arizona.149 Commentators have suggested that stakeholders may take
differing views regarding the ruling’s application, and may appeal the vacatur order.150 It is
therefore possible that, on appeal, the district court’s order could be reversed and the Navigable
Waters Protection Rule could be reinstated (either nationwide, or in parts of the country that are
not subject to the court’s order). In response to the order, however, 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.151
Meanwhile, the Corps and EPA have begun the stakeholder engagement process. On July 30,
2021, the Corps and EPA signed a notice of public meeting dates and solicited preproposal
feedback from interested stakeholders on defining WOTUS and implementing the definition.152
The notice, published in the Federal Register on August 4, 2021, included a schedule for public
meetings to take place in August 2021 and solicited written public comment on or before
September 3, 2021.153 The agencies specified several issues in the notice for which they are
particularly interested in obtaining feedback, including implementation of the various prior and
current regulatory regimes; regional, state, and tribal interests; science; environmental justice

147 Id. at 8-9.
148 Id. at 9-10.
149 Id. at 10.
150 Hannah Northey and Pamela King, “What’s next for WOTUS after judge jettisons Trump rule,” Greenwire, August
31, 2021, https://subscriber.politicopro.com/article/eenews/2021/08/31/whats-next-for-wotus-after-judge-jettisons-
trump-rule-280131. Another court that granted the United States’ motion for remand after the Pasqua Yaqui order
noted that it “would not be inclined to impose vacatur” had the Arizona district court not mooted the question of
whether vacatur was appropriate, because there had been “no evaluation of the merits—or concession by defendants—
that would support a finding that the rule should be vacated.” Order Granting Motion to Remand, California v. Regan,
No. 3:20-cv-03005, Doc. No. 271 (N.D. Cal. Sept. 16, 2021); Order Granting Motion to Remand, Waterkeeper
Alliance, Inc. v. EPA, No. 18-cv-03521, Doc. No. 125 (N.D. Cal. Sept. 16, 2021); see also Memorandum Opinion and
Order Granting Motion to Remand and Finding Vacatur Issue Now Moot, Pueblo of Laguna v. Regan, No. 1:21-cv-
00277, Doc. No. 40 (D.N.M. Sept. 21, 2021) (granting the United States’ remand motion, but finding the question of
whether the Navigable Waters Protection Rule should be vacated to be moot following the Arizona district court’s
decision). One other court has granted the United States’ motion for remand and vacated the Navigable Waters
Protection Rule, adopting similar reasoning to the Pasqua Yaqui court. Memorandum Opinion and Order, Navajo
Nation v. Regan, No. 2:20-cv-00602, Doc. No. 43 (D.N.M. Sept. 27, 2021). For more general discussion of the practice
of vacating agency action or issuing injunctions nationwide, see CRS Report R46902, Nationwide Injunctions: Law,
History, and Proposals for Reform, by Joanna R. Lampe.
151 See EPA, “Definition of ‘Waters of the United States’: Rule Status and Litigation Update,” September 3, 2021,
https://www.epa.gov/wotus/definition-waters-united-states-rule-status-and-litigation-update.
152 Department of the Army and EPA, “Notice of Public Meetings Regarding ‘Waters of the United States,’” press
release, July 30, 2021, https://www.epa.gov/wotus/notice-public-meetings-regarding-waters-united-states.
153 Corps and EPA, “Notice of Public Meetings Regarding ‘Waters of the United States’; Establishment of a Public
Docket; Request for Recommendations,” 86 Federal Register 41911, August 4, 2021. Corps and EPA, “Notice of
Public Meetings Regarding ‘Waters of the United States’; Establishment of a Public Docket; Request for
Recommendations,” Prepublication version Federal Register, July 29, 2021.
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interests; climate implications; the scope of jurisdictional tributaries, jurisdictional ditches, and
adjacency; and exclusions from the definition.154
Some Members of Congress have been critical of the Biden Administration’s actions to date.
Some have been supportive of the Administration’s intent to develop a new rule to replace the
Navigable Waters Protection Rule, but criticized the Administration for not immediately repealing
the rule.155 Others have criticized the Administration for not providing a sufficient period of time
for stakeholder input, and have asked the Corps and EPA to extend their public meeting schedule
and public comment period to ensure meaningful input.156
Potential Impacts of Revised WOTUS Definitions
The potential impacts of the Navigable Waters Protection Rule remain relevant even though the
Biden Administration has indicated that it has halted implementation of the rule and plans to
rescind and replace it with a new definition of WOTUS. As a practical matter, the Corps and EPA
have not yet addressed what regulatory regime will apply to projects that are already under way.
If an appeal of the Arizona district court’s decision results in a reversal of the August 30 vacatur
order or a revision of the scope of the order to limit it to the parties to the litigation, the Navigable
Waters Protection Rule could go back into effect in at least some parts of the country.
Additionally, the agencies may consider the Navigable Waters Protection Rule and stakeholder
comments on it when determining how to define WOTUS in a new regulatory action.
As the foregoing discussion of the controversy over WOTUS suggests, the Biden
Administration’s decisions about definitions will incorporate policy choices about the scope of
waters that the CWA should address. Stakeholder comments about the final Navigable Waters
Protection Rule reflected that policy issue, as observers highlighted potential impacts and
challenges that could arise as the rule was implemented. Because the Navigable Waters Protection
Rule narrowed the definition of WOTUS, CWA requirements and programs no longer applied to
waters that were previously subject to CWA requirements but no longer qualified as WOTUS.
The reductions in federal protection created by the rule and the potential impacts of the changes
in scope were likely to differ among states. Likewise, if the Corps and EPA develop a new
definition of WOTUS that is broader than the one established in the Navigable Waters Protection
Rule, more waters will be subject to CWA programs and requirements.
Changes in Federal Protection
In narrowing the scope of federal jurisdiction, the Navigable Waters Protection Rule protected
fewer waters than were protected under prior regulations. One challenge in assessing any
WOTUS definition is that the impacts and effects of particular definitions can be difficult to
identify with precision. This section illustrates how that uncertainty was manifest in stakeholders’

154 Ibid.
155 House Committee on Transportation and Infrastructure, Subcommittee on Water Resources and Environment,
“Chairs DeFazio, Napolitano Statements from the Subcommittee’s First Hearing in a Series on President Biden’s Fiscal
Year 2022 Budget Request,” press release, June 24, 2021, https://transportation.house.gov/news/press-releases/chairs-
defazio-napolitano-statements-from-the-subcommittees-first-hearing-in-a-series-on-president-bidens-fiscal-year-2022-
budget-request.
156 Committee on Transportation and Infrastructure, “Graves & Rouzer Ask Biden Administration to Extend its Brief
Public Comment Period & Meetings on Waters of the United States,” press release, August 26, 2021,
https://republicans-transportation.house.gov/news/documentsingle.aspx?DocumentID=405571.
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evaluations of the Navigable Waters Protection Rule, but similar questions arose under the 2015
Clean Water Rule—and are likely to continue in further rulemaking by the Biden Administration.
Using the Navigable Waters Protection Rule as an example, stakeholders held differing views
regarding how many wetlands and streams would have been excluded from federal jurisdiction
under that rule, as well as the degree to which such excluded waters could have been protected or
managed under state laws and regulations.
Estimates of Changes in Jurisdiction
In evaluating the impact of the Navigable Waters Protection Rule, some attempted to estimate
how many of the nation’s wetlands and streams might be excluded from federal jurisdiction under
the Navigable Waters Protection Rule. Many observers cited estimates prepared by EPA and
Corps staff in 2017, and obtained through the Freedom of Information Act.157 These estimates
indicated that the proposed Navigable Waters Protection Rule would have excluded at least 18%
of streams and 51% of wetlands nationwide from federal protection under the CWA.158 The
estimates were higher in the Arid West, where 35% of all streams, comprising 39% of stream
length, are ephemeral.159
However, in a fact sheet accompanying the issuance of the final Navigable Waters Protection
Rule, the Corps and EPA dismissed the estimates and asserted that they were “highly unreliable
and are based on stream and wetland datasets that were not created for regulatory purposes and
which have significant limitations.”160 The agencies also noted that prior administrations similarly
did not use maps to estimate changes in jurisdiction when issuing 2003 and 2008 guidance from
the SWANCC and Rapanos decisions, nor when the 2015 Clean Water Rule was promulgated.161
The Corps and EPA addressed this issue again in their June 2021 press release announcing the
Biden Administration’s intent to revise the definition of WOTUS. Based on a review of Corps

157 Ariel Wittenberg and Kevin Bogardus, “EPA falsely claims ‘no data’ on waters in WOTUS rule,” E&E News,
December 11, 2018, https://www.eenews.net/stories/1060109323. Audubon Society, New Federal Water Rules Ditch
Protections for Wetlands and Small Streams, January 23, 2020, https://www.audubon.org/news/new-federal-water-
rules-ditch-protections-wetlands-and-small-streams. Environmental Law Institute, WOTUS Proposal Poses Challenge
for States, February 18, 2019, https://www.eli.org/vibrant-environment-blog/wotus-proposal-poses-challenge-states.
Center for American Progress, Debunking the Trump Administration’s New Water Rule, March 27, 2019,
https://www.americanprogress.org/issues/green/news/2019/03/27/467697/debunking-trump-administrations-new-
water-rule/.
158 The Corps and EPA used two datasets to generate their 2017 estimates. They used the U.S. Geological Survey
National Hydrography Dataset (NHD) to estimate the percentages of streams that are perennial, intermittent, and
ephemeral. They also used the NHD and the U.S. Fish and Wildlife Service National Wetlands Inventory (NWI) to
generate estimates of the percentages of wetland acres that intersect streams that are perennial, intermittent, and
ephemeral, as well as wetland acres that do not intersect streams. The agencies’ analysis showed that nationwide, 18%
of streams (both in length and in number) are ephemeral (and thus would not be covered under the Navigable Waters
Protection Rule). The agencies’ analysis also indicated that 51% of NWI-mapped potential wetlands by acreage do not
intersect any NHD stream feature, and therefore may not be considered adjacent under a definition that requires that an
adjacent wetland “touch” a WOTUS. See Corps and EPA internal briefing slides, available at https://www.eenews.net/
assets/2018/12/11/document_gw_05.pdf.
159 Ibid.
160 Army Corps and EPA, Mapping and the Navigable Waters Protection Rule Fact Sheet, January 2020,
https://www.epa.gov/sites/production/files/2020-01/documents/nwpr_fact_sheet_-_mapping.pdf. For example, they
assert that “the NHD—even at high resolution—cannot differentiate between intermittent or ephemeral flow in most
parts of the country,” and that the NWI “does not contain information sufficient to evaluate whether those mapped
wetlands meet the definition of ‘adjacent wetlands’ under previous regulations or under the final rule.”
161 Ibid.
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data, the agencies found clear indicators of a substantial reduction in waters covered under the
Navigable Waters Protection Rule compared to previous rules and practice, particularly in arid
states.162
Regional Differences in Jurisdictional Changes
Because the status of ephemeral and intermittent waters has been a significant issue in successive
rulemakings, states where such waters are common may experience greater changes in federal
jurisdiction from rule to rule. The Corps, EPA, and observers generally agree that the Navigable
Waters Protection Rule excluded more waters from federal jurisdiction in some regions of the
United States than others based on differences in climate. The Arid West, for example, has many
waterways that are dry for much of the year, but can experience high flows after storm events.
Such waterways, under the Navigable Waters Protection Rule, would likely have been considered
ephemeral and no longer under federal jurisdiction.163 Other, wetter, regions of the United States
may have had comparatively fewer waterbodies lose federal protection.164
Ability of States to Address Reduced Federal Jurisdiction
Another significant question with respect to the Navigable Waters Protection Rule, and likely
with any future rulemaking, is the balance between federal jurisdiction and state and local actions.
Some observers argue that whatever changes resulted from reduced federal jurisdiction under the
Navigable Waters Protection Rule (as compared to other historical or potential definitions of
WOTUS) could be addressed, at least in part, by state and local programs and actions. States’
abilities to manage waters that are not WOTUS may vary for reasons such as current state laws
and regulations as well as differing permitting authority among states.
Differing State Laws and Regulations
In the preamble to the Navigable Waters Protection Rule, EPA noted that nothing in the rule or the
CWA prevents states from protecting nonjurisdictional waters through their own actions.165
Critics of broad assertion of federal jurisdiction over water resources point out that many states
have authorities to regulate waters of their state, often beyond the scope of federal jurisdiction.166
Other observers argue that many states effectively adopt the scope of federal CWA jurisdiction as
a factor that determines their own agencies’ authority to regulate waters.167 The Corps and EPA

162 June 2021 Press Release.
163 U.S. EPA and Department of the Army, Resource and Programmatic Assessment for the Navigable Waters
Protection Rule: Definition of “Waters of the United States,” January 23, 2020, p. 22, https://www.epa.gov/sites/
production/files/2020-01/documents/rpa_-_nwpr_.pdf (hereinafter “Resource and Programmatic Assessment”).
164 Association of State Wetland Managers, ASWM Insights on the Final WOTUS Rule: The 2020 Navigable Waters
Protection Rule, April 2020, p. 5, https://www.aswm.org/pdf_lib/aswm_insights_on_final_wotus_rule_final_5.7.20.pdf
(hereinafter “ASWM Insights”).
165 Navigable Waters Protection Rule, p. 22334.
166 U.S. EPA, “EPA and Army Deliver on President Trump’s Promise to Issue the Navigable Waters Protection Rule -
A New Definition of WOTUS,” press release, January 23, 2020, https://www.epa.gov/newsreleases/epa-and-army-
deliver-president-trumps-promise-issue-navigable-waters-protection-rule-1. U.S. EPA, “More Widespread Support for
EPA and Army’s Navigable Waters Protection Rule—A New Definition of WOTUS,” press release, January 24, 2020,
https://www.epa.gov/newsreleases/more-widespread-support-epa-and-armys-navigable-waters-protection-rule-new-
definition.
167 Resource and Programmatic Assessment, pp. 42-46. See also ASWM Insights, p. 4. See also 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
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compiled information on state authorities in developing the Navigable Waters Protection Rule.
The agencies concluded that “approximately half or more of the states regulate at least some
waters beyond the scope of federal CWA requirements,”168 but that many states face some
constraints in their current authority to fill gaps. For example:
 “There are some state laws that constrain the state’s authority to regulate more
broadly than the federal ‘floor’ set by the CWA in various respects.”
 “Thirteen states have adopted laws that require their state regulations to parallel
federal CWA regulations.”
 “Some state laws limit the application of state regulations to certain industries,
certain types of permits, or certain types of resources. Such requirements exist in
six states.”
 “Seven states have enacted requirements that no environmental state agencies can
promulgate state regulations beyond what is required under federal regulations.
These requirements include limits on geographic jurisdiction of state regulations
to match CWA jurisdiction.”
 “Twenty-four states have adopted laws that require extra steps or findings of
benefits in order to impose state regulations beyond federal requirements.”
 “Twenty-one states and the District of Columbia do not appear to have any laws
that address state regulations outside the scope of CWA jurisdiction.”169
The prevalence of constraints and absence of protections broader than federal requirements in
many states indicate that, in these states, there would be at least some time in which the
Navigable Waters Protection Rule would reduce protections for waters with no countervailing
state authority to regulate those waters. State legislators have the ability to alter their statutes or
enact additional protections, irrespective of whether a new rule issued by the Biden
Administration changes the universe of waters that are considered WOTUS. Addressing the
changes, however, would require time and resources to take on these responsibilities and to
develop effective programs.170
Differing Permitting Authority
The potential impacts of changes in federal jurisdiction in states may also vary depending upon
whether the state or a federal agency (i.e., EPA or the Corps) is the CWA permitting authority.
Specifically, if a state already has a permitting program established, that state may be able to
address any reductions in coverage more easily than a state that does not have such a program
because it has already established the legal, logistical, human resource, and financial
infrastructure for permit program administration.
The CWA authorizes states to assume administration of the two key permitting programs under
the statute—National Pollutant Discharge Elimination System (NPDES) permits under CWA

(hereinafter “ELI State Constraints Report”).
168 Resource and Programmatic Assessment, p. 45.
169 Resource and Programmatic Assessment, pp. 45-46.
170 ASWM Insights, pp. 4-5. See also Letter from Allison Woodall, Association of Clean Water Administrators
President, to Andrew Wheeler and R.D. James, April 15, 2019, https://www.acwa-us.org/documents/acwa-comments-
on-revised-definition-of-waters-of-the-united-states-proposed-rule/, p. 6 (hereinafter “ACWA Comment Letter”).
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Section 402 and dredge and fill permits under CWA Section 404.171 If states apply to EPA to
administer either program and meet statutory criteria, then EPA must approve those states’
assumption of their programs. Almost all states (with the exception of Massachusetts, New
Hampshire, and New Mexico) have assumed administration of their CWA Section 402 NPDES
permitting programs. In the three states that have not, EPA is the permitting authority. In contrast,
three states (Florida, Michigan, and New Jersey) have assumed administration of their CWA
Section 404 dredge and fill permitting programs. In the other 47 states, the Corps is the permitting
authority.172 When a state assumes administration of its CWA Section 404 permitting program, its
administration applies only to assumed waters, while the Corps continues to administer the CWA
for retained waters.173
According to the Association of State Wetland Managers, interest in state assumption of the
Section 404 program increased following the SWANCC and Rapanos rulings, which narrowed
federal protections for certain waters.174 Many states have explored assumption, and some
continue to pursue it.175 Many have explored but ultimately not pursued assumption, citing
barriers such as lack of funding to administer a state program, uncertainty over the extent of
waters that can be assumed, and significant modifications to state regulatory programs that would
be necessary.176
Programmatic Impacts
Changes to the scope of waters subject to federal jurisdiction under the CWA also affect the
applicability of CWA requirements and programs to many waters and wetlands. Affected
provisions and programs include water quality standards, impaired waters, and total maximum
daily loads; water quality certifications; CWA permitting programs; and other CWA and non-
CWA programs. With respect to the Navigable Waters Protection Rule, some of the potential
programmatic impacts were highlighted in stakeholder responses, the rule’s preamble, and the

171 CWA §§402(b) and 404(g); 33 U.S.C. §§1342(b) and 1344(g).
172 EPA approved Michigan’s and New Jersey’s requests to assume their CWA §404 permitting programs in 1984 and
1994, respectively. EPA approved Florida’s request to assume its CWA §404 permitting program in 2020 (85 Federal
Register 83553, December 22, 2020).
173 Under CWA §404(g) the Corps retains responsibility for waters “which are presently used, or are susceptible to use
in their natural condition or by reasonable improvement as a means to transport interstate or foreign commerce
shoreward to their ordinary high water mark, including all waters which are subject to the ebb and flow of the tide
shoreward to their mean high water mark, or mean higher high water mark on the west coast, including wetlands
adjacent thereto.” EPA has recognized that the uncertainty over assumable waters needs clarification, has taken initial
steps to revise existing CWA §404(g) regulations, and has included it on the agency’s Spring 2021 Unified Regulatory
Agenda. See U.S. Environmental Protection Agency, “Current Efforts Regarding Assumption under CWA Section
404,” https://www.epa.gov/cwa404g/current-efforts-regarding-assumption-under-cwa-section-404; Office of
Information and Regulatory Affairs, Spring 2021 Unified Agenda of Regulatory and Deregulatory Actions, EPA/Office
of Water, Clean Water Act 404 Assumption Update Regulation, RIN No. 2040-AF83.
174 Leah Stetson and Jeanne Christie, Expanding the States’ Role in Implementing CWA §404 Assumption, Association
of State Wetland Managers, November 10, 2010, p. 2, https://www.aswm.org/pdf_lib/
expanding_states_role_implementing_cwa_section_404_assumption_111810.pdf.
175 Association of State Wetland Managers, Status and Trends Report on State Wetland Programs in the United States,
2015, p. 29, https://www.aswm.org/pdf_lib/state_summaries/
status_and_trends_report_on_state_wetland_programs_in_the_united_states_102015.pdf. See also Association of State
Wetland Managers, Assumption Frequently Asked Questions—Fall 2020, https://www.aswm.org/pdf_lib/
assumption_faq.pdf.
176 Ibid.
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Economic Analysis and Resource and Programmatic Assessment the Corps and EPA developed
for the final rule.177
Water Quality Standards, Impaired Waters, and Total Maximum Daily Load
Programs (CWA Section 303)
CWA Section 303(c) requires states to adopt water quality standards for WOTUS.178 They may
also adopt standards for additional surface waters if their own state laws allow them to do so.179
Water quality standards are the foundation for a number of CWA programs. They establish the
water quality goals for waterbodies, including which designated uses the waterbody should
support (e.g., recreation, fish consumption, public water supply) and the conditions in the water
body necessary to support those uses (e.g., concentrations of pollutants).180 States are required to
review their water quality standards at least once every three years, and EPA is required to review
and approve or disapprove any new or revised standards for WOTUS.181
To the extent that a definition of WOTUS narrows the scope of federal jurisdictional waters in
comparison to prior regulations and practice, then states would not be required to maintain (or
adopt new) water quality standards for excluded waters. States may or may not opt to continue to
apply and enforce their water quality standards in such nonjurisdictional waters. If they decide to
maintain or adopt water quality standards for nonjurisdictional waters, EPA would no longer be
required to review them. As the Corps and EPA noted in the Navigable Waters Protection Rule
Resource and Programmatic Assessment, “should they choose, states and tribes may apply
standards under state or tribal law for waters that are not ‘waters of the United States,’ but they
would not be in effect for CWA purposes.”182 In contrast, any new definition of WOTUS that
broadens the scope of jurisdictional waters would require states to adopt water quality standards
for those waters.
The definition of WOTUS is also relevant to the identification and development of requirements
for waters that are not achieving water quality standards (also known as “impaired waters”). CWA
Section 303(d) requires states to identify any impaired waters on a biannual basis.183 This list of
impaired waters is also known as the 303(d) list. CWA Section 303(d) also requires that, for any
impaired waters, states establish total maximum daily loads (TMDLs) for pollutants that prevent
or are expected to prevent the attainment of water quality standards. A TMDL, essentially a
“pollution diet” for a water body, is the maximum amount of a pollutant that a water body can
receive and still meet water quality standards, allocated among the pollutant’s sources (including
a margin of safety).184

177 Resource and Programmatic Assessment. See also EPA and Department of the Army, Economic Analysis for the
Navigable Waters Protection Rule: Definition of ‘Waters of the United States,’ January 22, 2020, p. 59,
https://www.epa.gov/sites/production/files/2020-01/documents/econ_analysis_-_nwpr.pdf (hereinafter “Economic
Analysis”).
178 33 U.S.C. §1313(c). “States” collectively refers to states, territories, and authorized tribes.
179 CWA §510; 33 U.S.C. §1370.
180 See CWA Section 303(c)(2)(A) for designated uses and criteria. Note that water quality standards also include an
antidegradation policy, per CWA Sections 101(a) and 303(d)(4)(B). Also see EPA’s implementing regulations at 40
C.F.R. §131.
181 CWA §303(c); 33 U.S.C. §1313(c).
182 Resource and Programmatic Assessment, p. 60.
183 33. U.S.C. §1313(d).
184 40 C.F.R. §130.2.
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In responding to the proposed and final Navigable Waters Protection Rule, some observers
expressed concern that the narrower WOTUS definition may exclude some impaired waters and
waters with established TMDLs.185 The Corps and EPA acknowledged that the change in scope
could affect existing and future 303(d) lists and TDML restoration plans, noting that states might
not assess nonjurisdictional waters and may identify fewer waters as impaired and therefore
develop fewer TDMLs.186 They further acknowledged that “this could result in reduced protection
for aquatic ecosystems if other mechanisms for restoration are not available or utilized.”187 The
Corps and EPA also noted that states may be better “able to focus limited resources on assessing
and developing TMDLs for more priority waters that otherwise might be delayed due to the need
to assess all federal waters within state borders. The result may be greater ecological restoration
of high priority resources earlier.”188 To the extent that the Navigable Waters Protection Rule is
replaced by the pre-2015 regulations or a broader definition of WOTUS, more waters will be
subject to the protections afforded by inclusion on a 303(d) list, but states will again need to
develop a greater number of TMDLs.
CWA Permitting Programs (CWA Sections 402 and 404)
CWA Section 301 prohibits the discharge of pollutants from any point source (i.e., a discrete
conveyance, such as a pipe, ditch, etc.) to WOTUS without a permit.189 For both of the CWA
permitting programs—authorized under CWA Sections 402 and 404—the requirement for a
permit is triggered when there is a discharge into a WOTUS. Consequently, the Navigable Waters
Protection Rule reduced the scope of waters subject to CWA permitting.190 However, the extent of
the potential impacts of reduced federal jurisdiction on CWA permitting under CWA Sections 402
and 404 is not entirely certain and could vary across states based on how states address the
changes (e.g., by modifying their regulatory programs). Further rulemaking on WOTUS may
once again change the scope of waters subject to CWA permit requirements, though it is not yet
certain how that scope would compare to the waters covered under prior regulatory definitions.
CWA Section 402 NPDES Permitting
Under CWA Section 402, the discharge of any pollutant from a point source into a WOTUS
requires an NPDES permit.191 A narrower WOTUS definition, therefore, would reduce the
number of point-source discharges that require a permit. The Corps and EPA have stated that
some existing or new NPDES permits may still be needed even if a water that was jurisdictional
under prior regulations is no longer jurisdictional.192 For example, under the Navigable Waters
Protection Rule, discharges that travel through nonjurisdictional conveyances (such as an
ephemeral stream), but reach WOTUS, would still have required a permit.193 However, in such

185 Corps and EPA, The Navigable Waters Protection Rule—Public Comment Summary Document, Topic 11:
Economic Analysis and Resource and Programmatic Assessment, April 21, 2020, pp. 15, 43-46.
https://www.regulations.gov/document/EPA-HQ-OW-2018-0149-11574. See also ACWA Comment Letter, p. 7.
186 Navigable Waters Protection Rule, p. 22333.
187 Resource and Programmatic Assessment, p. 62.
188 Ibid.
189 33 U.S.C. §1311.
190 Navigable Waters Protection Rule, p. 22333.
191 33 U.S.C. §1342.
192 Navigable Waters Protection Rule, p. 22333 and Resource and Programmatic Assessment, p. 79.
193 Ibid.
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cases, the permittee may have been able to request a modification to its permit to account for
potential dilution of the pollutant that may have occurred before it reached jurisdictional
waters.194 In contrast, under any potential new definition of WOTUS that expands the scope of
jurisdictional waters, NPDES permits would be required for discharges to any waters that become
jurisdictional.
CWA Section 404 Dredge and Fill Permitting
Under CWA Section 404, the discharge of dredged or fill material into WOTUS, including
wetlands, requires a Section 404 permit.195 Such discharges may be associated with pipeline
projects, water resource projects, mining projects, or other development. The Section 404
permitting process requires a permit applicant to demonstrate that they have taken steps to avoid
impacts to wetlands, streams, and other aquatic resources; that potential impacts have been
minimized; and that compensatory mitigation will be provided for all remaining unavoidable
impacts.196
As with Section 402 NPDES permits, a broader definition of WOTUS would expand the scope of
waters and wetlands that require Section 404 permits, and a narrower definition of WOTUS
would reduce the scope. Accordingly, under the Navigable Waters Protection Rule, waters
(including wetlands) that were previously considered jurisdictional, but no longer qualified as
WOTUS, could be filled by developers and other project proponents without a Section 404
permit. In the Economic Analysis accompanying the Navigable Waters Protection Rule, the Corps
and EPA acknowledged that absent any state or local programs to address such activities,
developers or other project proponents might not take steps to avoid, minimize, or mitigate
impacts in nonjurisdictional waters and wetlands.197 As mentioned previously, in the Corps and
EPA’s press release announcing their intent to revise the definition of WOTUS, the agencies
stated that they were “aware of 333 projects that would have required Section 404 permitting
prior to the Navigable Waters Protection Rule, but no longer do.”198
In addition, stakeholders have observed that states considering the feasibility of assuming their
CWA Section 404 permitting programs may have to adjust their analyses in light of any potential
new definition of WOTUS. In a comment letter on the proposed Navigable Waters Protection
Rule, the Association of Clean Water Agencies (ACWA) explained that “a narrowing of federal
jurisdiction may impact [ACWA members’] evaluation of the efficiencies gained by assuming
404 programs as they may be assuming less waters.”199 This could ultimately impact the number
of states that decide to pursue assumption of their CWA Section 404 programs.
Water Quality Certifications (CWA Section 401)
Changes to the definition of WOTUS also have an impact on the extent to which states and tribes
may use CWA Section 401 water quality certifications to manage their waters. Under CWA
Section 401, any applicant for a federal license or permit to conduct any activity that may result
in any discharge into WOTUS shall provide the federal licensing or permitting agency a CWA

194 Navigable Waters Protection Rule, p. 22333 and Economic Analysis, p. 59.
195 33 U.S.C. §1344.
196 40 C.F.R. § 230.
197 Economic Analysis, p. 68.
198 June 2021 Press Release.
199 ACWA Comment Letter, p. 9.
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Section 401 certification that the project will comply with applicable provisions of certain
sections of the CWA, including state water quality standards.200 CWA Section 401 provides states,
certain tribes, and in certain circumstances, EPA (i.e., certifying authorities) the authority to grant,
grant with conditions, deny, or waive certification of proposed federal licenses or permits that
may result in a discharge into WOTUS. If a certifying authority denies certification, the federal
licensing or permitting agency cannot issue the license or permit. If a certifying authority grants
the certification with conditions, those conditions must become a term of the federal license or
permit if one is issued. Consequently, some states view CWA Section 401 certification as a
critical tool to manage and protect the quality of waters within their states.201 In addition, some
states rely on CWA Section 401 water quality certification procedures to protect wetlands in lieu
of assuming CWA Section 404 permitting authority, recognizing that they have the ability to
affect the federal permit and to exercise some regulatory control over wetlands without the
expense of establishing independent state programs.202
The authority of states and other certifying authorities under CWA Section 401 directly depends
upon whether a permit issued by a federal agency under Sections 402 or 404 is required for
waters within the states. The narrower scope of WOTUS under the Navigable Waters Protection
Rule (or any future rule that narrows the scope of WOTUS) would have reduced the number of
federal permits required, thereby affecting how often states exercised their CWA Section 401
authority.203 Under the Trump Administration, EPA published a final rule (the Section 401
Certification Rule) updating regulations on water quality certification on July 13, 2020.204 The
rule included numerous changes to prior regulation and practice that narrowed the authority of
certifying authorities when acting on Section 401 certification requests. (For further discussion of
the rule and related policy issues, see CRS Report R46615, Clean Water Act Section 401:
Overview and Recent Developments, by Laura Gatz and Kate R. Bowers.)
When considered together, the Navigable Waters Protection Rule and the Section 401
Certification Rule would likely have considerably narrowed states’ ability to use water quality
certification to manage their waters, for example by imposing conditions on federal project
permitting. In addition to revising the definition of WOTUS, however, the Biden Administration
has announced its intent to reconsider and revise the Section 401 Certification Rule.205
Accordingly, the interplay between the two sets of potential regulatory changes could have
implications for the water quality certification process.
CWA Section 311
CWA Section 311 prohibits discharges of oil or hazardous substances in harmful quantities into or
upon specified waters, including the navigable waters of the United States or adjoining

200 33 U.S.C. §1341.
201 See, for example, Letter from Western Governors’ Association, National Conference of State Legislatures, and
National Association of Counties, et al. to Honorable John Barrasso and Honorable Tom Carper, November 18, 2019,
https://www.acwa-us.org/wp-content/uploads/2019/11/Coalition-Letter-Clean-Water-Act-Section-401-Legislation-11-
18-19.pdf.
202 Association of State Wetland Managers, Status and Trends Report on State Wetland Programs in the United States,
2015, pp. 12-13, https://www.aswm.org/pdf_lib/state_summaries/
status_and_trends_report_on_state_wetland_programs_in_the_united_states_102015.pdf.
203 Navigable Waters Protection Rule, p. 22333. Economic Analysis, p. 29.
204 EPA, “Clean Water Act Section 401 Certification Rule,” 85 Federal Register 42210-42287, July 13, 2020.
205 EPA, “Notice of Intent to Reconsider and Revise the Clean Water Act Section 401 Certification Rule,” 86 Federal
Register 29541, June 2, 2021.
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shorelines, or waters of the contiguous zone.206 It also requires reporting spills of harmful
quantities to the federal government and authorizes the federal government to respond to and
enforce penalties for discharges into waters subject to CWA jurisdiction. Implementation of the
CWA Section 311 program cannot be delegated to states or tribes, so the scope of the program is
directly tied to the scope of WOTUS.
A discussion of CWA Section 311 and the Oil Pollution Act’s regulatory scheme is outside of the
scope of this report. However, broadly speaking, a reduction in jurisdictional waters under the
Navigable Waters Protection Rule, or any other potentially narrowed definition of WOTUS, may
reduce the applicability of the CWA oil spill prevention, preparedness, and response programs
and the associated Oil Spill Liability Trust Fund. For example, requirements to develop and
implement certain spill prevention and preparedness plans depend on whether a facility poses a
reasonable potential for a discharge to reach a water subject to CWA jurisdiction.207 If waters that
could be affected by a spill from a facility are no longer considered jurisdictional under a
narrowed definition of WOTUS, prevention and preparedness plans may no longer be required.208
In addition, the Oil Spill Liability Trust Fund—which is available to reimburse costs of assessing
and responding to oil spills in waters subject to CWA jurisdiction—is not available for waters
outside CWA jurisdiction.209 Therefore, costs incurred by states or tribes to clean up spills in
waters no longer considered jurisdictional, and costs related to business impacts associated with
those spills, might not be reimbursed, and the responsible parties might not be subject to federal
penalties.210 In contrast, under any potential new definition of WOTUS that expands the scope of
jurisdictional waters, the CWA Section 311 program would be applicable to those additional
jurisdictional waters.
CWA Financial Assistance Programs
EPA administers a number of financial assistance programs under the CWA, including the Section
106 Water Pollution Control Grant Program, the Section 319 Nonpoint Source Management
Grant Program, the Section 320 National Estuary Program, and various grant programs
authorized under CWA Section 104(b)(3). Some stakeholders have expressed concern about the
potential impacts of changes in CWA jurisdiction on various CWA financial assistance
programs.211 In its Resource and Programmatic Assessment accompanying the Navigable Waters
Protection Rule, however, the Corps and EPA concluded that they did not anticipate that the final
rule would affect EPA’s current CWA financial assistance programs, as the scope of these grant
programs is not linked to CWA jurisdiction.212 For example, funds from some of these programs
have long supported projects and efforts for waters that are not jurisdictional, such as
groundwater.

206 33 U.S.C. §1321(b)(3) prohibits discharges of oil or hazardous substances “(i) into or upon the navigable waters of
the United States, adjoining shorelines, or into or upon the waters of the contiguous zone, or (ii) in connection with
activities under the Outer Continental Shelf Lands Act or the Deepwater Port Act of 1974, or which may affect natural
resources belonging to, appertaining to, or under the exclusive management authority of the United States (including
resources under the Fishery Conservation and Management Act of 1976.”
207 Resource and Programmatic Assessment, p. 70.
208 Ibid.
209 Economic Analysis, p. 32; Resource and Programmatic Assessment, p. 71.
210 Ibid.
211 Navigable Waters Protection Rule, p. 22334.
212 Navigable Waters Protection Rule, p. 22334; Resource and Programmatic Assessment, pp. 87-90.
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CWA Enforcement
When a discharge of pollutants into WOTUS occurs without a permit (or other authorization or
exemption) or in violation of a permit, the CWA provides for administrative, civil, and criminal
enforcement actions.213 The enforcement authorities for each of the CWA permitting programs
depend on whether a state has assumed the permitting. Both states and EPA are authorized to
enforce NPDES permits in the 47 states that have assumed administration of their NPDES
programs. In the three states where EPA is the permitting authority, EPA is authorized to enforce
those permits. In the three states that have assumed their Section 404 permitting programs, the
state, the Corps, and EPA are authorized to enforce permits. In the 47 states that have not assumed
their Section 404 programs, the CWA authorizes the Corps and EPA to enforce permits.
Waters that are no longer considered WOTUS (whether under the Navigable Waters Protection
Rule or any future rule that narrows the scope of WOTUS) would fall outside of the scope of the
Corps and EPA’s enforcement authorities under the CWA.214 If subsequent revisions expand the
definition of WOTUS, any enforcement actions would likely be based on the rule that was in
effect at the time of the discharge. However, as EPA and the Corps noted in the Navigable Waters
Protection Rule Resource and Programmatic Assessment, “nothing in the revised definition of
‘waters of the United States’ affects the ability of states and tribes to apply and enforce
independent authorities over aquatic resources under state or tribal law.”215 As discussed in the
permitting section above, the extent to which states are able or decide to permit waters that fall
outside the scope of WOTUS (and enforce those permits) may vary across states.
Other Potential Program Impacts
In addition to these CWA programs, the Navigable Waters Protection Rule Resource and
Programmatic Assessment also describes potential impacts on other EPA programs—including
the Safe Drinking Water Act and the Resource Conservation and Recovery Act—as well as other
federal programs, such as the National Environmental Policy Act, the Endangered Species Act,
and the National Historic Preservation Act.216 These programs, and impacts on them from either
the Navigable Waters Protection Rule or a revised definition of WOTUS, are outside the scope of
this report.
Congressional Interest and Options
Considering the numerous court rulings, ongoing legal challenges, and issues that successive
administrations have faced in defining 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. Moving forward, Congress may be interested in overseeing the
Biden Administration’s efforts to review and potentially revise the definition, or introducing
legislation that provides a definition of the term or expresses a clearer intent as to how Congress
believes the term should be defined. In the 117th and 116th Congresses, some committees have
held hearings and some Members introduced legislation related to the scope of WOTUS.

213 CWA enforcement actions are authorized under CWA §§309, 311, and 404.
214 Resource and Programmatic Assessment, p. 92
215 Ibid.
216 Resource and Programmatic Assessment, pp. 93-101.
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117th Congress
In the 117th Congress, the Senate Environment and Public Works Committee and the House
Transportation and Infrastructure Committee, Subcommittee on Water Resources and
Environment, have held hearings which included discussion of the Biden Administration’s plans
to develop a new definition of WOTUS.217 While some Members have criticized the Corps and
EPA’s stated intent to rescind the Navigable Waters Protection Rule, others have criticized the
agencies for allowing the rule to remain in effect. In addition, some Members have introduced
free-standing legislation related to the definition of WOTUS. Two of these bills would enact the
Navigable Waters Protection Rule’s definition of WOTUS into law. Other proposed legislation
would amend the CWA to add a narrower definition of navigable waters. Because WOTUS is a
statutory phrase that defines navigable waters, a different definition of the latter term could
obviate the need to interpret the former, though it could introduce new interpretive questions.
 H.R. 2660, the “Withstanding Attempts to Encroach on our Resources (WATER)
Act,” would amend the CWA to codify the definition of WOTUS as revised
under the Navigable Waters Protection Rule.
 H.Res. 318 and S.Res. 17 would express the sense of the House and Senate,
respectively, that clean water is a national priority and that the Navigable Waters
Protection Rule should not be withdrawn or vacated.
 H.R. 4570 and S. 2168, identical bills titled the “Define WOTUS Act of 2021,”
would amend the CWA to change the definition of navigable waters. The
language, as introduced, would narrow the scope of waters subject to CWA
jurisdiction in comparison to the Navigable Waters Protection Rule. It would also
amend the CWA to make changes to the Corps process for making jurisdictional
determinations.218
 S.Con.Res. 5, a concurrent budget resolution passed by the Senate and adopted
by the House, included a provision that would allow for adjustments related to
preserving the continued implementation of the categories of jurisdictional and
excluded waters in the Navigable Waters Protection Rule. The amendment that
added the provision (S.Amdt. 655) was agreed to by yea-nay vote (51-49).
 S. 2517, the “Defense of Environment and Property Act of 2021,” would amend
the CWA to change the definition of navigable waters. The language, as
introduced, would narrow the scope of waters subject to CWA jurisdiction in
comparison to the Navigable Waters Protection Rule. It would also prohibit the
use of a significant nexus test; nullify the 1986 Corps Rule, 2008 Guidance, and
any subsequent regulation or guidance that defines or interprets the terms
navigable waters or WOTUS; and prohibit the Corps and EPA from
promulgating any rules or issuing any guidance that expands or interprets the
definition of navigable waters unless authorized by Congress. It would also

217 U.S. Congress, House Committee on Transportation and Infrastructure, Subcommittee on Water Resources and
Environment, President Biden’s Fiscal Year 2022 Budget Request: Agency Policies and Perspectives (Part I), 117th
Cong., 1st sess., June 24, 2021; U.S. Congress, House Committee on Transportation and Infrastructure, Subcommittee
on Water Resources and Environment, President Biden’s Fiscal Year 2022 Budget Request: Agency Policies and
Perspectives (Part II), 117th Cong., 1st sess., July 14, 2021. U.S. Congress, Senate Committee on Environment and
Public Works, Hearing on the Nomination of Michael S. Regan to be Administrator of the Environmental Protection
Agency, 117th Cong., 1st sess., February 3, 2021, S.Hrg. 117-1.
218 This bill was previously introduced in the 116th Congress.
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amend the CWA to make changes to the Corps process for making jurisdictional
determinations.219
 S. 2567, the “Navigable Waters Protection Act of 2021,” would enact into law the
Navigable Waters Protection Rule’s definition of the term waters of the United
States.
116th Congress
Multiple hearings in the 116th Congress also discussed WOTUS.220 During these hearings, some
Members expressed support for the Trump Administration’s efforts to more clearly and narrowly
define WOTUS, while others opposed its efforts and expressed concern about the loss of
protection for many waterways across the nation. In addition, some Members introduced free-
standing legislation related to the definition of WOTUS. One of these bills would have prohibited
implementation of the Navigable Waters Protection Rule and required the Corps and EPA to
promulgate a new regulation. Other proposed legislation would have, among other things,
repealed or nullified the 2015 Clean Water Rule and amended the CWA to add a narrower
definition of navigable waters.
 H.R. 6745, the “Clean Water for All Act,” would have nullified the Navigable
Waters Protection Rule and prohibited the Corps and EPA from implementing or
enforcing it. It would have also required the Corps and EPA to promulgate a
regulation defining WOTUS within two years, subject to certain requirements
laid out in the bill.
 H.R. 667, the “Regulatory Certainty for Navigable Waters Act,” would have
repealed the 2015 Clean Water Rule and amended the CWA by changing the
definition of navigable waters. The language, as introduced, would have
narrowed the scope of waters subject to CWA jurisdiction in comparison to the
2015 Clean Water Rule. It would have also amended the CWA to make changes
to the Corps process for making jurisdictional determinations (i.e.,
determinations as to whether a water body is jurisdictional under the CWA).
 H.R. 2287, the “Federal Regulatory Certainty for Water Act,” would have
nullified the 2015 Clean Water Rule and amended the CWA by changing the
definition of navigable waters. The language, as proposed, would have narrowed
the scope of waters subject to CWA jurisdiction in comparison to the 2015 Clean
Water Rule.

219 This bill was previously introduced in the 116th Congress.
220 U.S. Congress, House Committee on Transportation and Infrastructure, Subcommittee on Water Resources and
Environment, The Administration’s Priorities and Policy Initiatives Under the Clean Water Act, 116th Cong., 1st sess.,
September 18, 2019, H.Hrg. 116-31. U.S. Congress, Senate Committee on Environment and Public Works, Hearing on
the Nomination of Andrew Wheeler to be Administrator of the Environmental Protection Agency, 116th Cong., 1st sess.,
January 16, 2019, S.Hrg. 116-9. U.S. Congress, Senate Committee on Environment and Public Works, A Review of
Waters of the U.S. Regulations: Their Impact on States and the American People, 116th Cong., 1st sess., June 12, 2019,
S.Hrg. 116-45. U.S. Congress, Senate Committee on Environment and Public Works, Oversight of the Environmental
Protection Agency, 116th Cong., 2nd sess., May 20, 2020, S.Hrg. 116-391. U.S. Congress, Senate Committee on
Environment and Public Works, Stakeholder Reactions: The Navigable Waters Protection Rule under the Clean Water
Act, 116th Cong., 2nd sess., September 16, 2020.
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Author Information

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

Disclaimer
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