EPA and Corps Propose Significantly Narrower WOTUS Definition in Supplemental Rulemaking

Introduction

In September 2026, the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers (the Agencies) published a Supplemental Notice of Proposed Rulemaking (SNPRM) that would further revise the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). 91 Fed. Reg. 57284 (Sept. 9, 2026). The SNPRM builds on the Agencies’ November 2025 Notice of Proposed Rulemaking (NPRM), 90 Fed. Reg. 52498 (Nov. 20, 2025), and leaves much of that proposal unchanged. Its proposed changes, however, would significantly limit the scope of CWA coverage nationally.

The SNPRM focuses on two key jurisdictional requirements: “relatively permanent” flow and “continuous surface connection” (CSC). It would also add “perennial” as a defined term. In effect, the proposal offers, as an alternative to the NPRM’s wet-season standards, proposed requirement that water to be present essentially year-round.

Regulatory Background

In Sackett v. EPA, 598 U.S. 651 (2023), the U.S. Supreme Court rejected the “significant nexus” approach to CWA jurisdiction previously described by Justice Kennedy’s concurring opinion in Rapanos v. United States, 547 U.S. 715 (2006). The Sackett Court held that wetlands are WOTUS only when they are “as a practical matter indistinguishable from waters of the United States.” That standard requires a “continuous surface connection” to a relatively permanent body of water connected to traditional navigable waters.

In November 2025, the Agencies proposed to clarify these concepts. Under the 2025 NPRM, “relatively permanent” waters would be those that are standing or continuously flowing “year-round or at least during the wet season.” 90 Fed. Reg. 52498, 52545. The NPRM would define CSC as “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” Id. The SNPRM would substantially tighten both standards.

Key Changes in the SNPRM

Relatively Permanent Flow and the New “Perennial” Standard

The 2026 SNPRM preserves the “relatively permanent” requirement, but it would sharply narrow what that term covers. Relatively permanent waters would be limited to “perennial bodies of water,” with perennial defined as “having standing or continuously flowing water every day of the year during ordinary conditions.” 91 Fed. Reg. at 57301. The proposal includes two narrow exceptions:

• Anomalous events. A water would not lose jurisdiction if it dries up because of anomalous events such as drought or a dry spell. The Agencies are considering treating only “extreme (D3)” and “exceptional (D4)” conditions on the U.S. Drought Monitor as qualifying droughts. The SNPRM proposes to limit qualifying drought to a continuous period of no more than five years. After that, the drought conditions would be treated as the “new normal,” and the water’s jurisdictional status would be assessed under those conditions. 91 Fed. Reg. at 57290–91.
• Non-anomalous events. A water could dry up for “no more than a single period of up to 30 consecutive days in any given year” because of events such as low tide or a regularly occurring dry spell. 91 Fed. Reg. at 57288.

Continuous Surface Connection: Abutment No Longer Enough

The SNPRM would define CSC as “perennial surface water in a wetland that is continuously connected with the surface water in the jurisdictional water such that it is difficult to determine where the jurisdictional water ends and the wetland begins.” 91 Fed. Reg. at 57301. The same exceptions for anomalous and non-anomalous events would apply.

Under the SNPRM, abutment alone would no longer establish adjacency or CSC. The Agencies reason that a wetland that merely touches a jurisdictional water does not necessarily make it difficult to tell where the water ends and the wetland begins, which is how they read Sackett. Instead, a perennial surface water connection would be required. Only the portion of a wetland that is indistinguishably part of the jurisdictional water would itself be jurisdictional.

Practical Implications

If finalized, the SNPRM would likely remove a substantial number of wetlands and other features from federal jurisdiction. The Agencies themselves anticipate the greatest reduction in federally jurisdictional waters in the arid West, where intermittent streams drive much of the hydrology. The proposed changes may also be pronounced in the Upper Midwest, where bogs and similar wetlands are often saturated without showing year-round surface water. In those settings, the perennial-flow and CSC requirements would apparently be much harder to meet than the NPRM’s wet-season tests.

The SNPRM could also affect waters whose jurisdiction depends on a connection through intervening ditches, wetlands, or other features that do not otherwise carry perennial flow or perennial surface water.

Whether the NPRM or the SNPRM are finalized remains uncertain, and any final rule will likely face legal challenges. Fredrikson will continue to track the rulemaking as it progresses.

For more information or questions, contact Tom Brett or Jeremy Greenhouse.