Trump Administration Releases Supplemental Proposal to Further Amend Waters of the United States Subject to Federal Jurisdiction

On September 9, 2026, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (“the agencies”) published a supplemental notice of proposed rulemaking to provide additional regulatory options for narrowing the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). The agencies developed the supplemental proposal options after reviewing approximately 220,000 comments submitted on their previous November 2025 WOTUS proposal, which was developed in response to Sackett v. EPA (2023). The agencies have opened a 30-day comment period on the proposal, with comments due October 9, 2026.

The supplemental proposal does not replace, withdraw or reopen every element of the November 2025 WOTUS proposal. Instead, it proposes new additional alternative definitions for several key WOTUS-related terms including “relatively permanent,” “continuous surface connection” and ”perennial.” It also proposes changes to covered wetlands. 

The agencies issued the supplemental proposal partly in response to comments raising concerns about whether the November 2025 proposal’s undefined “wet season” approach could apply consistently across different regions and support a legally durable final rule. The agencies now seek comment on the newly proposed supplemental options. The agencies are seeking comment on the following elements:

• Relatively permanent: the supplemental proposal would generally limit this category to perennial bodies of water that ordinarily contain standing or continuously flowing water year-round. The proposal provides exceptions for temporary interruptions in two circumstances: (1) “anomalous events resulting in extraordinary circumstances,” or unexpected events, such as extreme or exceptional droughts or (2) “non-anomalous events” resulting in more than one normal, temporary interruption of no more than 30 consecutive days in any given year, such as low tide or a regularly occurring dry spell.
• Perennial: the agencies propose defining perennial as “having standing or continuously flowing water every day of the year during ordinary conditions.” The agencies also alternatively propose “surface water flowing continuously year-round” consistent with the 2020 Navigable Waters Protection Rule. 
• Continuous surface connection: the supplemental proposal would define “continuous surface connection” to mean “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.” This would require a wetland to contain perennial surface water that is continuously connected with an otherwise jurisdictional water, making the boundary between the wetland and jurisdictional water indistinguishable. The definition would allow interruptions caused by unusual events, such as drought, or one predictable interruption lasting no more than 30 consecutive days per year. Only the portion of the wetland that is indistinguishably part of the jurisdictional water would be considered jurisdictional under this approach. 
• Wetlands: the agencies proposal to revise the current category of adjacent wetlands to include only perennial wetlands that are indistinguishably connected to a jurisdictional water (e.g., traditional navigable water, territorial seas, jurisdictional impoundment or a jurisdictional tributary). The agencies are also seeking comments on whether the terms “adjacent” or “abutting” should be removed from the definition of ”continuous surface connection” entirely. 

Implications 

As proposed, the supplemental proposal would significantly narrow waters subject to federal CWA jurisdiction. The agencies expect that most intermittent streams would not satisfy the proposed perennial standard. They also identify the arid West as the region where the change could have the greatest effect since intermittent and ephemeral streams account for much of the regional hydrology. The agencies also note that the dredge and fill permitting program in section 404 of the CWA would likely see the most programmatic changes under these proposed changes, anticipating reductions in permits and required mitigation.

Background

WOTUS is a threshold term under the CWA used to establish the scope of federal jurisdiction for protecting specific waters and wetlands. The CWA defines “navigable waters” as “the waters of the United States, including the territorial seas” but does not specifically define WOTUS itself. As a result, the agencies have defined the term by regulation since the 1970s. The scope of WOTUS has since been debated and litigated for decades, resulting in numerous rulemakings.

In its 2023 Sackett v. EPA opinion, the U.S. Supreme Court overruled its 2006 significant nexus test and held that the CWA covers wetlands only when they are indistinguishable from jurisdictional waters through a continuous surface connection. The agencies amended the 2023 WOTUS rule after the decision and proposed further regulatory revisions in November 2025. The supplemental rule adds alternatives to that pending rulemaking that would further narrow the scope of the nation’s waters and wetlands that receive federal protections.

How BBK Can Help

BBK will continue to monitor developments of the proposed rule as well as the legal and policy implications. For questions about how the regulation may impact ongoing or proposed public infrastructure projects or to submit comments, please contact BBK’s Government Affairs team.