On May 25, the Supreme Court of the United States decided Sackett v. EPA, a long running dispute over the scope of Clean Water Act authority over adjacent wetlands (in which your humble author was lead counsel for the Sacketts for several years, and co-counsel at the Supreme Court). In Sackett, the Supreme Court unanimously rejected the significant nexus test from Justice Kennedy’s lone concurring opinion in Rapanos. And a majority of the Court adopted the Rapanos plurality’s test for adjacent wetlands: only those wetlands with a continuous surface connection to other regulated waters, such that the two are indistinguishable, are regulable under the Act. The majority explicitly rejected the argument that wetlands separated from other regulated waters by berms, dunes, levees, and the like are subject to Clean Water Act authority.

The result of the Sackett decision for the Biden Administration’s recently adopted regulation defining “navigable waters” is not entirely clear, but this much is certain: The portion of the rule that regulates wetlands solely on the basis of the significant nexus test, 33 C.F.R. § 328.3(a)(4)(iii), is invalid as a matter of law. And the decades-old definition of “adjacent” in 33 C.F.R. § 328.3(c)(2) is largely abrogated. From “[a]djacent means bordering, contiguous, or neighboring. Wetlands separated from other waters of the United States by man-made dikes or barriers, natural river berms, beach dunes, and the like are ‘adjacent wetlands,’” the only text to survive Sackett is “Adjacent means contiguous.”

A question remains about the Biden Rule’s use of the significant nexus concept to define regulated tributaries and lakes and ponds. Sackett was decided based on the unanimous Court’s conclusions that the significant nexus test is not a valid interpretation of the Clean Water Act, and the majority’s conclusion that the property in question was not adjacent to any other water as a matter of law. Sackett does not appear to address how widely the Clean Water Act regulates non-navigable tributaries, and it does not pick up the Rapanos plurality’s discussion of this topic. From that perspective, the Biden Rule’s inclusion of tributaries, lakes, and ponds solely using the significant nexus concept might survive Sackett.

On the other hand, there was always some controversy over the agencies’ use of significant nexus to regulate non-navigable tributaries, since Justice Kennedy’s Rapanos concurrence did not do so. And the entire history of the agencies’ guidance and regulations applying the significant nexus concept, from the initial post-Rapanos guidance in 2007 through the 2023 Biden Rule, evinces reliance on the Kennedy concurrence as the basis for the concept. Now the Supreme Court has unanimously repudiated significant nexus as an invalid interpretation of the Clean Water Act. From this perspective, the Biden Rule’s provisions regulating tributaries, lakes, and ponds solely on significant nexus are in jeopardy, as well as the expansive definition of “significantly affect” in 33 C.F.R. § 328.3(c)(6), which the Biden Rule uses to implement significant nexus.

This chart highlights the provisions of the Biden Rule which are in doubt after Sackett, with “certainly illegal” provisions highlighted in red, and “now doubtful” ones in yellow.

Note from the Editor: The Federalist Society takes no positions on particular legal and public policy matters. Any expressions of opinion are those of the author. We welcome responses to the views presented here. To join the debate, please email us at [email protected].