The Environmental Protection Agency (EPA) and Army Corps of Engineers released a pre-publication of their Supplemental Notice of Proposed Rulemaking (SNPRM) to revise the definition of Waters of the United States (WOTUS).
The SNPRM accompanies the November 2025 WOTUS proposal and provides additional regulatory alternatives for public comment as the agencies work toward a final rule intended to align with the U.S. Supreme Court's decision in Sackett v. EPA. The action signals continued efforts by the Administration to create a narrower, more durable definition of federal Clean Water Act jurisdiction.
EPA is reopening discussion on several key jurisdictional concepts rather than only advancing the framework proposed in 2025.
In response to more than 220,000 public comments on the November 2025 proposal, EPA and the Corps are seeking input on alternative approaches for defining “relatively permanent” waters, “continuous surface connection,” and a new “perennial” standard. In addition, the Corps is simultaneously working on improving permitting and jurisdictional determination processes, including better use of technology to provide faster and clearer jurisdictional decisions.
Key changes proposed in the SNPRM:
• Relatively Permanent Standard Narrowed from "Wet Season" to "Perennial": The November 2025 proposal would have treated waters as relatively permanent if they flowed year-round or at least during the wet season. The supplement instead proposes a significantly narrower standard: waters generally must be perennial, meaning they have standing or continuously flowing water every day of the year under ordinary conditions.
• New Bright-Line 30-Day Temporary Interruption Allowance: A perennial water would remain jurisdictional if flow is interrupted by a single period of up to 30 consecutive days per year due to ordinary events such as low tide or a regularly occurring dry spell. Interruption beyond that threshold would generally disqualify the feature from being "relatively permanent".
• Wet-Season Concept Largely Replaced: The November 2025 proposal largely relied on the concept of the wet season for determining both relatively permanent waters and continuous surface connections. The supplemental proposal largely abandons that approach due to implementation and regional variability concerns.
• Continuous Surface Connection Tightened to Require Perennial Surface Water: The November 2025 proposal stated that wetlands have surface water at least during the wet season and abut a jurisdictional water. The supplement would require perennial surface water in the wetland that is continuously connected to surface water in the jurisdictional water.
Publication in the Federal Register of the supplemental proposal is expected this week. Once published, the proposal is open for a 30-day public comment period.
While EPA and the Corps did not provide a target date for a final rule, they stated that they intend to proceed as expeditiously as possible while considering public comments received on both the original proposal and the supplemental
APPA submitted comments on the November 2025 proposal and is now reviewing the supplemental proposal in detail. APPA continues to follow the evolution of the WOTUS definition because when members can reliably identify jurisdictional waters early, they can design projects to avoid impacts, target mitigation, and proceed without fear of later changes to jurisdictional determinations.
APPA said it will provide members with a more comprehensive analysis of the SNPRM this week and encouraged members to review the proposal and share any initial observations, concerns, or implementation questions to help inform APPA's advocacy efforts.
