On September 8, 2023, the United States Environmental Protection Agency and the United States Army Corps of Engineers (collectively, the Agencies) published a final rule (Agency Rule) to amend the definition of “waters of the United States” under the Clean Water Act. 88 Fed. Reg. 61964. The Agency Rule amends a definition of “waters of the United States” that the Agencies issued in January of this year. The new definition was necessitated by the holding of the Supreme Court of the United States in Sackett v. EPA, 598 U.S. _, 143 S. Ct. 1322 (2023), which construed waters of the United States more narrowly than the Agencies had. The stated purpose of the Agency Rule is to conform to the holding in Sackett. The Agency Rule went into effect immediately on September 8, 2023, that is, without opportunity for notice and comment.

The definition of “waters of the United States” determines the scope of the Agencies’ jurisdiction under the Clean Water Act to regulate discharges and dredge and fill activities in or to streams and wetlands. The Clean Water Act applies to “navigable waters,” which the statute further defines as “waters of the United States, including the territorial seas.” 33 U.S.C. §1362(7). The meaning of “waters of the United States” has been a source of controversy and litigation for decades. The Agencies’ definition of the term is codified in federal regulations found at 40 CFR §120.2 and 33 CFR §328.3. The Agency Rule modifies those sections of the federal regulations.

Before Sackett, the Agencies applied a definition derived from Justice Kennedy’s concurring opinion in Rapanos v. United States, 547 U.S. 715 (2006). The Kennedy concurrence extended jurisdiction not only to waters and wetlands that have a relatively permanent surface connection to traditional navigable waters, but also those having a "significant nexus" to—that is, that could “significantly affect the chemical, physical, and biological integrity of”—waters that are or reasonably could be made navigable in fact. The Kennedy test also defined “adjacent” for purposes of determining which wetlands are jurisdictional, to include those that are bordering, contiguous to, or neighboring other waters of the United States, even if the wetlands are separated from such waters by manmade barriers such as dams or dikes. 

In Sackett, the Supreme Court held that the “significant nexus” test and the above definition of “adjacent” are inconsistent with the text and structure of the Clean Water Act. The Court held that the Agencies’ jurisdiction extends only to “relatively permanent, standing or continuously flowing tributaries connected to traditional navigable waters, the territorial seas, or interstate waters; relatively permanent, standing or continuously flowing additional waters with a continuous surface connection to such relatively permanent waters or to traditional navigable waters, the territorial seas, or interstate waters; and, adjacent wetlands and certain impoundments with a continuous surface connection to such relatively permanent waters or to traditional navigable waters, the territorial seas, or interstate waters.”

The Agency Rule tracks Sackett by eliminating the “significant nexus” test and defining “adjacent” (for purposes of wetlands) as “having a continuous surface connection.”

The Agency Rule does not clear up ambiguities that are left by the Sackett decision. Sackett does not define what “relatively permanent” or “continuous surface connection” mean, other than to say that a “temporary interruption” by “phenomena like low tides or dry spells” would not render a water body non-jurisdictional. The Agency Rule does not offer definitions of “relatively permanent” or “continuous surface connection.” It therefore does not provide guidance on often or how long a tributary could be dry or disconnected from a navigable water and still constitute “waters of the United States.” The decision and Agency Rule also are not clear on whether man-made features such as pipes that connect streams and wetlands to navigable waters have the requisite connection to themselves be jurisdictional. These and other issues left unresolved by Sackett, and the Agency Rule will undoubtedly be the source of further litigation. 

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