Coastal marsh. Beaufort County, SC. (Photo by Peter Ravella, CNT)

USA - "Waters Of The United States"—Where The Term Stands Now

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 Bayview, 2 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)
  3. Including corporations, states, and municipalities (see Section 502(5))
  4. From any point source (see Section 502(12))
  5. Into navigable waters of the United States (see Section 502(12)) ("WOTUS")
  6. Without a permit (Section 301)
  7. 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

Read more.