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“Waters Of The United States”—Where The Term Stands Now

Posted on March 14, 2023

By Wayne J. D’Angelo (New York) , Joseph Green (Los Angeles), Zachary Lee (Washington) and Sabrina Eve Morelli (New York) Kelley Drye & Warren LLP

The definition of the phrase “Waters of the United States” (WOTUS), encompassing the jurisdictional reach of the Clean Water Act (CWA or the Act) and the related Oil Pollution Act of 1990, has been a source of contention between administrations and federal courts since the Act’s passage in 1972. The Act regulates discharges of pollutants from point sources into “navigable waters,” which is further defined as “waters of the United States including the territorial seas.”1 Statutorily, many bodies of water are more plainly within this jurisdictional scope, including waters that are navigable in the traditional sense and the territorial seas.

However, the Environmental Protection Agency (EPA) and the Army Corps of Engineers (Corps), who share custody over the administration of the CWA, and permitted/regulated entities, have often grappled over whether wetlands and isolated, intermittent, and other “not so obvious” waters fall within the CWA’s purview.

Several Supreme Court decisions have addressed the definition of WOTUS.

In 1985, in United States v. Riverside Bayview2 the Court deferred to the Corps’ jurisdictional claim over wetlands adjacent to a traditional navigable water because they are “inseparably bound up” with navigable waters.

In Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC)3 in 2001, a 5-4 divided Court held that the use of “nonnavigable, isolated, intrastate waters” by migratory birds was not itself a sufficient basis for the exercise of authority under the CWA.

In the 2006 Rapanos v. United States case,4 the Court wrestled over whether WOTUS includes wetlands that at least occasionally empty into the tributary of a traditionally navigable water. The Court was unable to reach a majority in answering the question, and set out two differing tests on the matter. A four-Justice plurality created a rule commonly referred to as the “Relatively Permanent” or “Hydrological Connection” standard, which “includes only those relatively permanent, standing or continuously flowing bodies of water ‘forming geographic features’ that are described in ordinary parlance as ‘streams[,] . . . oceans, rivers, [and] lakes,’ ” and “wetlands with a continuous surface connection” to a “relatively permanent body of water connected to traditional interstate navigable waters.”

Justice Kennedy concurred with the judgement, but took another approach commonly referred to as the “Significant Nexus” test, concluding that “to constitute ‘navigable waters’ under the Act, a water or wetland must possess a ‘significant nexus’ to waters that are or were navigable in fact or that could reasonably be so made.” Both are described in more detail below.

Nevertheless, a workable standard was never agreed upon by a majority of the Justices, and different Administrations and courts have applied both tests in different situations, resulting in a fractured, inconsistent, and uncertain regulatory landscape.

Now, the Supreme Court is again tasked with assessing the jurisdictional reach of the CWA in Sackett v. EPA. The Justices have been briefed, and the Court heard oral argument in October of last year. Their deliberations are expected to conclude in Spring this year with the publication of their opinion.

Meanwhile, the Biden Administration published a final rule defining the scope of WOTUS on December 30, 2022, whereupon the Sackett plaintiffs and the U.S. Department of Justice issued dueling letters to the Court in response. The Biden Administration has also set forth plans to further specify the definition of WOTUS in a rule they plan to finalize in 2024.


The Clean Water Act (CWA) prohibits:

  1. A discharge of any pollutant (Section 301)
  2. By any person (Section 301)
    • Including corporations, states, and municipalities (see Section 502(5))
  3. From any point source (see Section 502(12))
  4. Into navigable waters of the United States (see Section 502(12)) (“WOTUS”)
  5. Without a permit (Section 301)
    • Or above the permitted amount

The Clean Water Act does not define “Waters of the United States.” Consequently, tremendous ambiguity exists as to what areas are within federal jurisdiction for Clean Water Act purposes. The standard used to delineate these jurisdictional boundaries directly impacts whether or not industry groups and landowners need permits to begin or continue projects on areas geographically close to navigable bodies of water. Regulated entities can suffer serious consequences for unpermitted discharges as well: the CWA contains hefty civil penalties of over $64,0005 per violation, and can even impose criminal liability, for unauthorized discharges into WOTUS.6

The Oil Pollution Act of 1990 (OPA 90), along with CWA Section 311, creates additional federal provisions for liability for the unpermitted release or discharge of oil in waters subject to the jurisdiction of the United States.7 OPA 90 also requires prevention plans for facilities where there is a reasonable expectation that an oil discharge could reach a jurisdictional water or adjoining shoreline. Like the CWA, the scope of the federal government’s jurisdictional authority under OPA 90 also hinges on what waters are designated as “waters of the United States” for CWA purposes. OPA 90 provides for potential civil penalties of over $250,000 per incident and up to 5 years in prison.8

Several administrations and federal courts have attempted to resolve this jurisdictional uncertainty by developing different standards for what areas qualify as a “Water of the United States.” Administrative changeover, challenges to agency rules, and splintered precedent in federal courts have led to frequent changes in the scope of the Clean Water Act. The result is widespread confusion and lack of clarity among the regulated community, the public, and federal and state regulators.


Rapanos v. United States

The U.S. Supreme Court last considered the definition of “WOTUS” for Clean Water Act purposes in Rapanos v. EPA in 2006. This action resulted in two different answers. Rapanos ended in a plurality decision, with strongest directives from Justices Scalia, who wrote the plurality opinion, and Kennedy, who wrote the concurring decision. Pending a decision in Sackett v. EPA, Rapanos remains the most current, albeit fractured, assessment of the scope of federal jurisdiction Congress contemplated through the phrase “WOTUS.”


The Rapanos case involved a developer who sought to fill three wetland areas on his property to build a shopping center. At the time, the regulations assessed wetlands to be “covered by the CWA as long as they are adjacent to traditionally navigable waters or tributaries of such waters,” and accordingly, the U.S. EPA asserted jurisdiction over the project under the CWA. After Rapanos ignored cease-and-desist orders from the EPA, the government brought civil suit against the developer. Affirming the district court, the Sixth Circuit agreed with the United States that the “hydrological connection” of the wetlands to navigable water brings them within federal jurisdiction. Rapanos appealed, claiming the CWA did not cover this land, but only traditionally navigable waters. The Court was asked to determine the types of connections between navigable bodies of water and adjacent wetlands that are sufficient to bring the wetlands within federal jurisdiction under the CWA.

Resulting Tests

Rapanos resulted in a 4-1-4 plurality decision that left the regulated community and legal practitioners with two different and inconsistent standards for determining whether a wetland adjacent to a traditionally navigable waterway qualify as WOTUS:

  • Justice Scalia’s “Relatively Permanent” Standard9 This standard holds that WOTUS can only refer to relatively permanent, standing or flowing bodies of water. Thus, wetlands containing occasional, intermittent, or ephemeral flows are not within federal jurisdiction. To be jurisdictional, the wetland must have a continuous surface connection with a navigable water that makes it difficult to determine where the water ends and the wetland begins. This standard limits the scope of the CWA because there are many adjacent wetlands, such as those featured n the Rapanos and Sackett facts, that do not have a surface-level connection to waterways at some points in the year.
  • Justice Kennedy’s “Significant Nexus” Standard: This standard holds that wetlands need not have a continuous surface connection to a continuously flowing body of water, and specifies that mere adjacency is not sufficient. Waters or wetlands adjacent to but not directly connected to navigable waterways must have a substantial effect on the chemical, physical, or biological integrity of the water body. If this is satisfied, then the federal government has jurisdiction over the area for Clean Water Act purposes.

Since Rapanos, as a general matter, EPA and the Corps have considered waters as subject to CWA jurisdiction if they meet either the “Relatively Permanent,” or the “Significant Nexus” standard, on a case-by-case basis. This has given way to inconsistent law throughout the country, fractured enforceability and unclear rights and obligations for regulated industries.

Obama and Trump Era Rules: Left With Nothing

In 2015, the Obama Administration finalized the Clean Water Rule.10 This rule did not establish any regulatory requirements, but attempted to clarify the scope of WOTUS for CWA purposes by focusing exclusively on Justice Kennedy’s Significant Nexus test. The rule asserted federal jurisdiction over eight categories of water bodies, which were intended to reduce the number of case-specific determinations for most geographic areas, but the more subjective Significant Nexus test created confusion and questions of fair notice over which (sometime subsurface) connections are significant enough to bring otherwise non-jurisdictional waterbodies and wetlands under federal jurisdiction.

In 2019, the Trump-era EPA repealed the Clean Water Rule. On January 23, 2020, the Trump Administration released the final version of the Navigable Waters Protection Rule (NWPR).11 Unlike the 2015 CWR, which was based on Justice Kennedy’s Significant Nexus test, the NWPR was largely based on Justice Scalia’s Relatively Permanent standard. As a result, substantially fewer waterbodies and wetlands would be subject to federal jurisdiction. However, a federal court vacated the NWPR in August of 2021 in Pasqua Yaqui Tribe v. U.S. EPA. 12

This cycle of creation, revocation, and vacatur has ultimately left those trying to understand the geographical jurisdiction of the CWA to rely solely on a 2008 Joint Memorandum by the EPA and U.S. Army Corps of Engineers for guidance on interpreting the Rapanos plurality decision.13

Sackett v. EPA II


Landowners Michael and Chantell Sackett began building a home near Priest Lake, Idaho, but were ordered to halt construction and begin restoration of the wetlands by the EPA, which determined the area was subject to CWA protection. The wetland is about 100 yards from the lake, separated by a roadway. The Sacketts filed suit against the EPA, asserting that their property does not fall within federal jurisdiction for CWA purposes. The pending case is commonly referred to as “Sackett II” because the Sacketts appeared in a separate suit against the EPA in 2012, where the Supreme Court unanimously allowed for pre-enforcement judicial review of jurisdiction determinations.14

Ninth Circuit Holding

On review, the Ninth Circuit applied the Justice Kennedy’s “Significant Nexus” test from Rapanos to determine “whether the wetlands, either alone or in combination with similarly situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as ‘navigable.’ “15 Because the court found that the wetlands in question “significantly affect the integrity of Priest Lake,” the Ninth Circuit deemed the Agency’s decision reasonable and granted summary judgement in favor of the EPA.

Supreme Court Grants Certiorari

The Supreme Court subsequently granted the Sacketts’ petition for writ of certiorari on September 22, 2021. The question for the Court here is whether the Ninth Circuit was correct in applying the Significant Nexus test.

The EPA argues that the Significant Nexus test from Rapanos controls. The Sacketts seek the rejection of this approach and, instead, put forth a standard similar to Justice Scalia’s in Rapanos that stipulates that a wetland may be regulated as part of WOTUS only when it: (1) is connected to a stream, ocean, river, lake, or other body of water by means of a continuous surface-water connection, such that it is difficult to tell where the wetland ends and the large body of water begins, and (2) the stream, ocean, river, lake or other such body of water is a Water of the United States (subject to Congress’ power over interstate commerce).

Oral arguments were heard in October of last year. Several justices were notably averse to the Significant Nexus test, signaling that the standard is too vague. Justice Gorsuch expressed deep concerns that there is no limiting principle, asking if wetlands ‘miles’ from a water body could satisfy the standard. Several justices’ concerns about the standard’s vagueness were tied to the fact that the CWA has criminal provisions.16

There also were, however, indicators that the justices found the Scalia test too narrow to achieve the purpose of the CWA. Chief Justice Roberts expressed concern over the test’s elimination of federal authority over wetlands that have a seasonal surface connection to large waterbodies. The justices notably honed in on the phrase “wetlands adjacent,” featured in Section 404(g) of the CWA, inquiring whether “adjacency” requires a physical connection to navigable waters, or if simply being nearby is adequate. Justice Kagan asked whether an alternative test, as opposed to the two pre-existing tests, could be formulated to provide certainty over jurisdictional boundaries while maintaining federal regulatory authority. Though neither side provided an answer to this inquiry, it could be indicative of a compromise and entirely new test.

The Court is expected to come down with its decision by the Spring of 2023. Some commentators find it unlikely that the Court’s conservative majority would defer to EPA’s standard, believing it to be too ambiguous.17 Depending on the outcome of their decision, a new standard for determining whether a wetland and other “non-navigable” water bodies are WOTUS, and could dramatically expand or contract the scope of the CWA and EPA’s authority. Agency permitting authority, enforcement power and rulemaking ability will be The Court is expected to come down with its decision by the Spring of 2023. Some commentators find it unlikely that the Court’s conservative majority would defer to EPA’s standard, believing it to be too ambiguous.17 Depending on the outcome of their decision, a new standard for determining whether a wetland and other “non-navigable” water bodies are WOTUS, and could dramatically expand or contract the scope of the CWA and EPA’s authority. Agency permitting authority, enforcement power and rulemaking ability will be inexorably bound by the constraints of the Court’s new definitional test, significantly impacting the entirety of the regulated community.

Biden Administration’s December 30, 2022 Finalized Rule

The Biden Administration issued yet another WOTUS final rule on December 30, 2022.18 In this final Revised Definition of the Waters of the United States rule, the U.S. EPA and Army Corp of Engineers define wetlands or seasonal streams that feed into permanent rivers or lakes as within the scope of the CWA so long as they significantly affect downstream waterways. In essence, the rule codified the standards put forth in Rapanos, and allowed federal jurisdiction to be asserted under either test, thereby significantly expanding the scope of federal jurisdiction.

Much of the rule’s approach stems from Justice Kennedy’s Significant Nexus standard. In addition, the agency notes with regard to Justice Scalia’s approach in Rapanos: “the relatively permanent standard is appropriate to include in this rule because, while it identifies only a subset of the ‘waters of the United States,’ it also provides important efficiencies and additional clarity for regulators and the public by more readily identifying a subset of waters that will virtually always significantly affect [navigable waters].”19 Various stakeholders dispute whether the new rule is clearer or easier to implement. The rule becomes effective 60 days after it was published in the Federal Register on January 18, 2023.20

It is not entirely clear how the rule will impact the forthcoming holding in Sackett II. Solicitor General Brian Fletcher notified the Court that the rule has been published, referring to Justice Kagan’s question regarding the status of the rulemaking during oral arguments. Fletcher also indicates in his letter that the final rule’s preamble addresses the regulatory definition of “adjacent,” providing guidance to landowners and addressing concerns raised in oral arguments about which adjacent wetlands qualify as WOTUS.

Letter from Sacketts to SCOTUS

The Sacketts responded to the new rulemaking, and the Solicitor General’s letter, on January 9, 2023. The Sacketts’ attorney, Damien Schiff, told the Justices in a letter21 that the government had left out crucial information regarding the justices’ questions about which wetlands the legislature intended the Clean Water Act to cover.

Schiff refers to the House floor debate on the 1977 conference report, indicating Congressional intent “omitted from” and allegedly contrary to that cited in the finalized rule’s preamble. The letter noted that in this report, Rep. Bauman inquired, “but what does ‘adjacent wetlands’ mean? How far will that go? I represent counties where when the tide comes up, a third of those counties could suddenly be adjacent wetlands.” To this, Rep. Clausen stated: “I would interpret the word ‘adjacent’ to mean immediately contiguous to the waterway.” This could serve as indicia to the Court of legislative intent in line with the ‘Scalia-like’ standard the Sacketts put forth.

Biden Administration Sets Stage for New 2024 Finalized Rule

Adding to this confusion, on January 11, the Biden Administration set plans to propose a second, newer definition of WOTUS in the Fall of 2023, with a goal of finalizing the proposal in July of 2024.22 The notification says little about what the ruling will consist of beyond stating its title: Revised Definition of “Waters of the United States.” The stipulated deadline for the Notice of Proposed Rulemaking is set for November of 2023. The contents of the rule will likely be constrained by the forthcoming ruling in Sackett II, which will be decided before the publication of the proposal.


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