Wetlands are among the most productive and protective ecosystems on our planet — filtering water, storing carbon, buffering floods, and sustaining biodiversity. They are also, since the Supreme Court’s 2023 decision in Sackett v. EPA, substantially less protected by federal law. By eliminating the ‘significant nexus’ test, Sackett shrunk federal power over millions of acres of wetlands. This final installment of our Earth Day series examines what that contraction means in practice for permitting, enforcement, development, and land use. We also survey how federal circuit courts have applied Sackett since 2023, trace the regulatory steps taken by the Trump administration, and briefly offer guidance for those who are navigating a compliance landscape that seems shifts with each new administration.

I. The Evolving Definition of ‘Waters of the United States’ Under the Clean Water Act — From Riverside Bayview to Sackett

The Clean Water Act of 1972 prohibits the discharge of pollutants into ‘navigable waters,’ defined in the statute as ‘waters of the United States.’ Congress left that phrase undefined, and the resulting interpretive struggle has generated three landmark Supreme Court decisions spanning nearly four decades — each narrowing federal jurisdiction from the last.

The story begins with United States v. Riverside Bayview Homes (1985), where a unanimous Supreme Court upheld the Army Corps of Engineers’ authority to regulate wetlands ‘adjacent’ to traditional navigable waters. The Court deferred to the Corps’ scientific judgment that wetlands adjacent to covered waters played a critical role in preserving the integrity of those waters. For nearly two decades, Riverside Bayview stood as the high-water mark of federal wetland jurisdiction.

The tide shifted in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC) in 2001. There, the Court held that the Corps could not assert jurisdiction over isolated, non-navigable ponds solely on the basis that they were used as habitat by migratory birds — the so-called ‘Migratory Bird Rule.’ The Court’s majority was skeptical of expansive federal power and signaled concern about the constitutional dimensions of the agencies’ interpretation. SWANCC left open, however, the extent to which waters with some hydrological connection to navigable waters could be regulated.

That question produced no consensus in Rapanos v. United States (2006). Four Justices, in a plurality written by Justice Scalia, concluded that the Clean Water Act reached only ‘relatively permanent, standing or continuously flowing bodies of water’ with a continuous surface connection to traditional navigable waters. Justice Kennedy, writing separately, articulated the ‘significant nexus’ test — a wetland could be regulated if it had a significant nexus to traditional navigable waters, meaning it significantly affected the chemical, physical, or biological integrity of those waters. Four dissenting Justices would have upheld agency authority more broadly. Because no single test commanded a majority, lower courts and the agencies were left to choose between the Scalia plurality and the Kennedy concurrence, with most circuits treating Justice Kennedy’s significant nexus test as the operative standard.

A period of regulatory instability followed. The Obama administration’s 2015 Clean Water Rule attempted to codify a broad interpretation of WOTUS, incorporating the significant nexus test and extending jurisdiction to many ephemeral and intermittent streams. That rule was challenged immediately, enjoined in about half the country, and ultimately repealed by the first Trump administration in 2020, which replaced it with the narrower Navigable Waters Protection Rule. The Biden administration, in turn, finalized a new WOTUS rule in January 2023 that largely restored pre-2015 coverage — only to have it rendered legally untenable by the Supreme Court’s decision just months later.

II. Sackett v. EPA (2023): The Court Settles the Question — Narrowly

On May 25, 2023, the Supreme Court issued its unanimous judgment in Sackett v. EPA, , though the Justices reached that result through three separate opinions. The case arose when Michael and Chantell Sackett began backfilling a lot near Priest Lake, Idaho, to build a home. The EPA asserted jurisdiction over the property under the Clean Water Act because the lot allegedly contained wetlands hydrologically connected — through a ditch and creek — to the navigable Priest Lake some distance away.

Justice Alito, writing for five Justices, resolved the Rapanos split in favor of Justice Scalia’s plurality. The Clean Water Act’s coverage of adjacent wetlands is limited to those that have a ‘continuous surface connection’ to a water that is itself a ‘water of the United States’ — meaning a relatively permanent, standing, or continuously flowing body of water. Wetlands separated from such a water by an upland, berm, dike, or other physical barrier, or connected only through a pipe, culvert, or subsurface flow, fall outside federal jurisdiction. The significant nexus test, which had governed federal practice in most circuits for seventeen years, was explicitly rejected. As the Court noted, no member of the nine-Justice Court defended that test as the correct legal standard.

Justice Kavanaugh, joined by three colleagues, concurred in the judgment but wrote separately to object to the majority’s conflation of ‘adjacent’ with ‘adjoining.’ In his view, the majority’s test was narrower than what the statute or agency practice had contemplated for decades, and it would leave many ecologically significant wetlands without any federal protection. Justice Kagan, also concurring, catalogued practical consequences of the ruling, warning that the majority had effectively rewritten the Clean Water Act. The ecological stakes could be substantial: estimates suggest the decision eliminated federal coverage over as many as 17 to 90 million acres of non-tidal wetlands nationwide — roughly 50 percent or more of previously protected wetland acreage.

III. How Federal Circuit Courts Have Applied Sackett

Since May 2023, federal circuit and district courts have uniformly applied Sackett’s continuous surface connection standard, often doing so to terminate long-running enforcement disputes or dismiss citizen suits that previously would have survived under the significant nexus test.

The Fifth Circuit was among the first appellate courts to apply the new standard. In Lewis v. United States (5th Cir. Dec. 18, 2023), the court ended a decade-long jurisdictional dispute between the Army Corps and a Louisiana landowner over the Corps’ assertion of Clean Water Act authority over wetlands on the subject property. Applying Sackett’s plain-language test without agency deference, the Fifth Circuit found that the record demonstrated simply no connection whatsoever between the alleged wetlands and any relatively permanent body of water connected to interstate navigable waters. The decision illustrates how Sackett’s bright-line rule can quickly resolve disputes that lingered for years under the more fact-intensive significant nexus framework.

The Eleventh Circuit applied Sackett in Glynn Environmental Coalition, Inc. v. Sea Island Acquisition, LLC (11th Cir. July 29, 2025), affirming dismissal of a Clean Water Act citizen suit challenging the filling of less than half an acre of wetlands on St. Simons Island, Georgia. The court invoked for the proposition that, to establish Clean Water Act applicability, the plaintiff environmental group had to allege (a) that the adjacent body of  water constitutes “waters of  the United States,”; and (b) that the wetland has a continuous surface connection with that water, making it difficult to determine where the “water” ends and the “wetland” begins.’”  The plaintiffs had alleged jurisdiction on the theory that the wetland was located in the same basin as a traditional navigable water and would eventually drain to such water through surface runoff, groundwater, and pipes. The Eleventh Circuit rejected each theory. Shared basin location is insufficient; eventual drainage through subsurface flow or groundwater is insufficient; and connection through culverts or pipes — without a continuous surface connection — is insufficient. The court articulated a clear pleading standard for citizen suits going forward: plaintiffs must allege both that the adjacent water body is itself a water of the United States and that the wetland has a continuous surface connection to that water with no clear demarcation between them.

Lower courts have consistently held that allegations of intermittent or seasonal surface flow, proximity to navigable waters, shared hydrological basins, or ecological significance are legally insufficient to establish jurisdiction. The result is a more predictable, defendant-friendly standard that appears to reduce enforcement exposure for landowners and developers — but also eliminates federal recourse for many wetland-related projects that previously would have required Section 404 permits from the Army Corps.

IV. The Trump Administration’s Response: Guidance, Rulemaking, and What to Expect

The Trump administration has moved aggressively to codify and extend Sackett’s restrictive framework through both guidance and notice-and-comment rulemaking.

On March 12, 2025, the EPA and the Army Corps issued a joint guidance memorandum clarifying how agency staff should implement Sackett’s continuous surface connection standard.  (Memorandum to the Field Between the U.S. Department of the Army, U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency Concerning the Proper Implementation of “Continuous Surface Connection” Under the Definition of “Waters of the United States” Under the Clean Water Act.)  The guidance rescinded prior Biden administration guidance documents and instructed field personnel to apply a narrower interpretation of when a wetland qualifies as ‘indistinguishable’ from a covered water. The agencies simultaneously announced a public comment process and a series of nine listening sessions held through April and May 2025 to gather stakeholder input on how to revise the WOTUS regulatory definition through formal rulemaking.

On November 17, 2025, EPA and the Corps published a proposed rule in the Federal Register that would formally revise the regulatory definition of WOTUS to align with — and in some respects go beyond — the Sackett framework. 2025-20402.pdf  The public comment period closed January 5, 2026, and the final rule is expected to be promulgated at some point in 2026. Key features of the proposal include: (1) a new definition of ‘relatively permanent’ limited to bodies of water flowing or standing year-round or at least during the wet season, expressly excluding ephemeral waters; (2) a new definition of ‘continuous surface connection’ requiring that a wetland both touch (abut) a jurisdictional water and have surface water present at least during the wet season; (3) removal of interstate waters as an independent jurisdictional category; (4) an express exclusion of groundwater; and (5) expanded exclusions for ditches, waste treatment systems, and converted croplands.

The proposed rule expressly acknowledges, as required, that states, tribes, and local governments retain authority under the Clean Water Act to impose more stringent requirements. Finalization of the rule is anticipated yet in 2026, though legal challenges are expected almost immediately. Given WOTUS litigation history — in which federal courts have enjoined prior WOTUS rules in various states within weeks of finalization — practitioners should plan for the possibility that the rule’s effective date will vary by jurisdiction pending judicial review.

V. Practice Tips for Environmental Lawyers Advising Developers and Companies

For practitioners advising project proponents in the post-Sackett environment, the following guidance reflects current best practices:

1. Obtain Jurisdictional Determinations Early. Request Approved Jurisdictional Determinations (AJDs) from the Army Corps at the outset of project planning. The Sackett standard makes AJDs more achievable for sites where wetlands lack continuous surface connections to covered waters, and an AJD provides a legally binding, five-year determination that can form the foundation for project approvals and financing.

2. Do Not Assume Federal Non-Jurisdiction Means No Permit. Even where a wetland falls outside federal CWA jurisdiction, state and local permits may still be required. Conduct a comprehensive survey of applicable state wetland laws and local ordinances before proceeding. The state-law landscape is in active flux, and several states are currently considering expansive revisions. Check for recent legislative or regulatory changes in any state where your client operates.

3. Monitor the Trump WOTUS Rulemaking and Resulting Litigation. The proposed rule is expected to be finalized in 2026, but legal challenges may result in injunctions that freeze the rule in some circuits while it takes effect in others. This creates the kind of split-jurisdiction landscape that practitioners saw during the Obama and first Trump administration WOTUS battles. Maintain current awareness of which rule governs your project’s jurisdiction on any given day.

4. Scrutinize the ‘Continuous Surface Connection’ Test in the Field. The legal standard may seem more simple than previously articulated standards – but it remains fact-intensive. Hydrological conditions vary seasonally, and the Trump proposed rule’s ‘wet season’ formulation may create disputes about what conditions trigger jurisdiction. Commission qualified wetland scientists and hydrologists to document site conditions across seasons where the status of a connection is not immediately obvious.

5. Evaluate Enforcement Risk Under Both Federal and State Regimes. Federal enforcement discretion has diminished significantly under the current administration, but state enforcement actions — including citizen suits under state environmental laws — remain a live risk in states with independent wetland programs.

6. Preserve the Administrative Record. In enforcement proceedings, the strength of your defense rely on the quality of the jurisdictional record. Preserve all documentation supporting a determination that a wetland lacked a continuous surface connection to covered waters, including site photographs, delineation reports, hydrology studies, and correspondence with the Army Corps.

This blog is the concluding installment in our Earth Day 2026 series on the erosion and evolution of federal environmental protections. The views expressed reflect general legal analysis and should not be construed as legal advice for any specific matter.

© 2026 | Environmental & Land Use Practice Group