On May 25, the U.S. Supreme Court issued its decision in Sackett v. EPA which substantially narrows the reach of Section 301(a) of the Clean Water Act (CWA), a provision that prohibits certain discharges of pollutants to navigable waters (waters of the United States) without a CWA permit. Determining the scope of the CWA’s definition of navigable waters, and in turn the propriety of the regulatory definitions established by EPA and the Army Corps of Engineers (ACOE) to define waters of the United States, is at the heart of this litigation.

This issue has been the subject of decades of differing rulemakings and litigation leading up to and following the Court’s decisions in U.S. v. Riverside Bay View Homes in 1985 (confirming CWA jurisdiction to wetlands adjacent to a traditional navigable water), Solid Waste Agency of Northern Cook County v. Army Corps of Engineers in 2001 (ACOE’s “migratory bird rule” extending jurisdiction to some intrastate isolated waters exceeded ACOE’s authority under the CWA), and Rapanos v. U.S. in 2006 (4-1-4 plurality opinion advancing alternative jurisdictional tests for adjacent wetlands). Since Rapanos, with successive federal administrations, EPA and ACOE have changed the regulatory scope of waters of the United States in 2015, 2020, and 2023 to alternatively expand, contract, and expand the CWA’s reach. The most recent regulatory definition became effective in March 2023. This definition followed in part a jurisdictional test established in a concurring opinion by justice Kennedy in Rapanos under which CWA jurisdiction extends to wetlands that have an ecologically significant nexus to adjacent traditional navigable waters. EPA’s 2023 rule promptly was stayed in 27 states after its adoption.

The Court’s majority opinion in Sackett (by Justice Alito, joined by Justices Roberts, Thomas, Gorsuch, and Barrett) largely reaches back to a non-controlling plurality opinion of four justices in Rapanos. In Sackett, the majority opinion first focused on the use of the term “waters” in the CWA definition of “navigable waters.” Consistent with the Rapanos plurality, the Sackett majority reasoned that Congress’s use of the term “waters” refers to an open body of water and covers “relatively permanent, standing or continuously flowing bodies of water ”…ordinarily described as “streams, oceans, rivers and lakes.”

With respect to wetlands, the majority interpreted a separate CWA provision added in 1977, section 404(g)(1), which authorizes states, with EPA’s approval, to partially assume and administer CWA permitting programs. Under this interpretation, wetlands that are adjacent to traditional navigable waters are understood to be included within (rather than additional to) “waters of the United States” and therefore such adjacent wetlands must “be indistinguishably part of a body of water that itself constitutes “waters” under the CWA.”

Further, the majority established a two-part test to establish that adjacent wetlands are jurisdictional:

1. First, the body of water adjacent to the wetlands must constitute a water[s] of the United States. This means it must be a “relatively perma­nent body of water connected to traditional interstate nav­igable waters”.
2. Second, the adjacent wetland must have a “continu­ous surface connection with that water, making it difficult to determine where the ‘water’ ends and the ‘wetland’ be­gins.”

In two concurring opinions, 4 justices (Kavanaugh, Sotomayor, Kagan and Jackson) joined only in the majority’s judgment (i) not to apply the significant nexus test for determining jurisdiction of adjacent wetlands and (ii) that the wetlands filled on the Sackett’s property were not jurisdictional, reversing and remanding the case to the 9^th Circuit Court of Appeals. These concurrences explain that the statute’s use of the term “adjacent” in section 404(g)(1)’s reference to wetlands adjacent to navigable waters is not limited only to wetlands that abut, adjoin, touch or are contiguous with navigable waters. Rather, the ordinary meaning of adjacent includes “lying near or close to, neighboring, or not widely separated.” These concurrences also stress that in eight consecutive Presidential administrations since 1977, EPA and ACOE’s regulatory definitions of “adjacent wetlands” have always included “not only wetlands adjoining covered waters, but also those wetlands separated from covered waters by a man-made dike or barrier, natural river berm, beach dune, or the like.” The concurrences additionally stress that the majority’s test interpreting adjacent to mean only “adjoining” or “contiguous” wetlands will strip jurisdiction over many “long-regulated and long-accepted-to-be-regulated wetlands” that play an important role in protecting the quality of adjacent water bodies, “with negative consequences for waters of the United States.”

At first blush, Sackett promises not only to constrain the reach of wetlands jurisdiction, but also may provide a degree of welcomed regulatory clarity and predictability by doing away with some of the technical and site-specific significant nexus determinations needed to evaluate whether a CWA permit is required to work in or fill an adjacent wetland. On the other hand, as the concurrences point out, there are bound to be gray areas and regulatory uncertainty even under the new Sackett test that could have been avoided by a rule that accepted adjacent wetlands regardless of whether they adjoin, abut or are indistinguishable from an adjacent regulated water body. These will play out through upcoming rulemakings and inevitable litigation as the federal government, states, public interest groups, and a broad array of regulated businesses adjust to this substantial change to the CWA regulation.