EPA and Army Corps Propose Narrower Definitions Affecting WOTUS Jurisdiction

On Sept. 9, the United States Environmental Protection Agency (“EPA”) and the United States Army Corps of Engineers (“Corps”) (collectively, the “Agencies”) published a Supplemental Notice of Proposed Rulemaking (“Proposed Rulemaking”) further revising the definition of “waters of the United States” (“WOTUS”) under the Clean Water Act.

The Proposed Rulemaking supplements the Agencies’ November 2025 proposed rule (“November Proposal”), which also sought to revise the WOTUS definition in light of the U.S. Supreme Court’s 2023 decision in Sackett v. EPA.

• There, the Supreme Court found that WOTUS only encompasses waters that are “relatively permanent, standing or continuously flowing,” and held that wetlands are jurisdictional waters only where they have “a continuous surface connection” to WOTUS.¹
• In response to their November Proposal, the Agencies received roughly 220,000 comments highlighting purported gaps in the proposed definitions, which the Agencies are now attempting to resolve with narrower and more restrictive definitions that still align with Sackett.

Public comments on the Proposed Rulemaking are due October 9, 2026.

Proposed Definition of “Relatively Permanent”

Under the Agencies’ supplemental option, “relatively permanent” waters would be limited to perennial bodies of water. The Agencies are seeking comment on two potential definitions of “perennial:” one defining it as waters with standing or continuously flowing water every day of the year during ordinary conditions, and another defining it as surface water flowing continuously year-round.

The proposed rule would allow for certain exceptions to the “every day of the year” or “year-round” requirement, including:

1. Anomalous events, such as drought, which can interrupt flow without stripping jurisdictional status, so long as the drought does not persist for more than five years; and
2. Non-anomalous events, such as low tide or a regularly occurring dry spell, which will not break jurisdiction as long as the interruption does not exceed a single 30-consecutive-day period in any given year.

Proposed Definition of “Continuous Surface Connection”

The Agencies also propose a narrower definition of “continuous surface connection,” which applies to wetlands. Rather than requiring only that a wetland “abut” or touch a jurisdictional water, the new definition would require the wetland to contain perennial surface water that is continuously connected to the surface water of the WOTUS.

The same “perennial” standard used for relatively permanent waters would also apply here, meaning a wetland would need a continuous, perennial surface-water connection to a jurisdictional water to qualify.

Wetlands would be subject to the same exceptions for anomalous and non-anomalous events described above.

Implications of the Narrowed Definitions

The Agencies acknowledge that the newly proposed definitions will significantly narrow how WOTUS is defined, resulting in many waters losing WOTUS status and jurisdiction.

The Agencies expect the arid Western United States to see the biggest impact, as many water sources will be unable to meet the new definition of “relatively permanent.” However, these changes  would not affect how such waters may be defined or protected under state or Tribal regulations.

Despite the narrower scope, the Agencies contend the refined definitions will “simplify implementation of the rule,” allowing WOTUS status to be determined through simple observation rather than significant analysis or professional consultation.

Next Steps

The comment period on the Proposed Rulemaking closes Oct. 9. Comments can be submitted here.

The Agencies are still reviewing comments on the November Proposal, including proposed changes not addressed by the Proposed Rulemakings, though the comment period for those other changes has closed.

For further information regarding Clean Water Act jurisdiction and related permitting issues, contact a member of Taft’s Environmental group.

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¹ Sackett v. Env’t Prot. Agency, 598 U.S. 651, 671, 684 (2023).