Over the past decade, the definition of “waters of the United States” (WOTUS) has shifted repeatedly, creating uncertainty for permitting and project planning. Building on the Supreme Court’s Sackett v. EPA decision, the EPA and the U.S. Army Corps of Engineers (together, the agencies) announced a proposal this week to further refine which water features qualify as WOTUS by narrowing key definitions and codifying — and expanding — exclusions. The proposal would apply across all Clean Water Act (CWA) programs that rely on WOTUS, including permitting under Sections 404 and 402, water quality certifications under Section 401, and Total Maximum Daily Loads (TMDLs) for impaired waters under Section 303. The proposal is directionally deregulatory, meaning fewer waters are likely to be considered federally jurisdictional and therefore regulated. The new definition was published in the Federal Register on Thursday, marking the start of a 45-day public comment period through January 5, 2026. The public comment page can be accessed here.

Today’s WOTUS regulatory landscape remains split. The “Amended 2023” WOTUS rule is operative in 24 states, the District of Columbia, and the territories, while the pre-2015 rule (as modified by Sackett) governs elsewhere. This new proposal aims to bring greater uniformity by redefining, excluding, and removing several key terms:

We expect that the proposal will reduce the number of federally jurisdictional waters, easing some Section 404 permitting, mitigation, cost, and delay challenges. Under Section 401, a reduced federal permitting footprint would yield fewer certifications and potentially less state or tribal conditioning. Under Section 402, some discharges to nonjurisdictional features may not require NPDES permitting; however, discharges that reach WOTUS could still trigger permitting requirements. Under Section 303, fewer waters may be covered under the federal standards, but states and tribes may try to fill regulatory gaps with additional, more localized regulation. The states and tribes may assume a larger role as federal jurisdiction narrows, resulting in program coverage and standards that may vary by jurisdiction.

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.
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