Key Contacts
Trump Administration Proposes Rule to Revise and Narrow Definition of “Waters of the United States”
With the stated purpose of providing more clarity, predictability and consistency, the Trump Administration is taking action to revise the definition of “Waters of the United States (“WOTUS”), a term that defines the scope of federal jurisdiction over Clean Water Act permitting. On November 20, 2025, the U.S. Environmental Protection Agency (“EPA”) and U.S. Army Corps of Engineers (the “Corps”) (collectively, the “Agencies”) jointly published a proposed rule (the “Proposed Rule”) to revise and clarify the much-litigated definition of WOTUS in light of the 2023 U.S. Supreme Court decision in Sackett v. EPA. In Sackett, the Court struck down the “significant nexus” test and held that WOTUS encompass only those relatively permanent, standing or continuously flowing bodies of water that are or are connected to a traditional interstate navigable water and wetlands that are indistinguishable from those waterbodies due to a continuous surface connection. The Proposed Rule expands upon that ruling with new definitions and exemptions that narrow the scope of waters over which there is federal jurisdiction and underscores the primary authority of States and Tribes in the regulation of their water resources.
Leaning into concepts discussed in Sackett and in the Court’s plurality opinion from United States v. Rapanos (2006), the Proposed Rule would establish the following five categories of WOTUS:
- Traditional navigable waters and the territorial seas (“(a)(1) waters”);
- Most impoundments of WOTUS (“(a)(2) impoundments”);
- Relatively permanent tributaries of traditional navigable waters, the territorial seas, and impoundments (“jurisdictional tributaries”);
- Wetlands adjacent (i.e., having a continuous surface connection) to traditional navigable waters, impoundments, and tributaries; and
- Lakes and ponds that are relatively permanent and have a continuous surface connection to a traditional navigable water, the territorial seas, or a tributary.
Notably, the Agencies propose to remove the category of “interstate waters” from the definition of WOTUS and, therefore, such waters would only be deemed to be WOTUS if they fall within another jurisdictional category in the WOTUS definition. Although the Agencies note in the preamble discussion that the elimination of these waters from federal jurisdiction will not have a significant impact since there are only a limited number of waters that are currently considered jurisdictional solely due to crossing a state line, this change represents a significant departure from prior regulatory formulations.
The Proposed Rule also would add definitions for “relatively permanent” and “continuous surface connection” for the first time. “Relatively permanent” waters would be defined as “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.” “Continuous surface connection” would be defined as “having a surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” These two definitions introduce the concept of “wet season” and the phrase “at least during the wet season” is intended to mean that the required surface hydrology would be required to be continuous throughout the entirety of the wet season. The Agencies state that this approach would serve as a bright line test while also allowing for regional variation given the range of hydrology and precipitation throughout the country. Notably, the Proposed Rule does not define wet season, however, the preamble to the Proposed Rule states that the Agencies intend to use the metrics from the Corps’ Antecedent Precipitation Tool (“APT”) as a primary source for identifying the wet season. That tool is currently used by the Corps to inform their wetland delineations and jurisdictional determinations. The Agencies solicit input on the proposal as well as alternative approaches to identifying the wet season and the meaning of relatively permanent waters and continuous surface connection, including whether the “wet season” concept should be scrapped for an alternative bright-line threshold. The Agencies also propose to reestablish definitions for “ditch,” “prior converted cropland,” “tributary,” and “waste treatment system.” Finally, the Proposed Rule would amend the waste treatment system, prior converted cropland, and certain ditch exclusions, as well as add an express exclusion for groundwater.
The Proposed Rule is characterized as a “deregulatory action” under Executive Order 14192 (Unleashing Prosperity Through Deregulation). The Agencies anticipate that the most significant impact of the Proposed Rule will be on the CWA section 404 program (the program regulating the discharge of dredged or fill material into WOTUS), potentially “reducing the number of [section] 404 permits issued and acres of wetland impacts mitigated relative to the baseline.” How States and Tribal governments will respond to federal deregulation of these waterbodies will be an issue to watch. While some States have challenged expansive federal WOTUS jurisdiction, others have been able to rely upon federal regulation for protection of these water resources. If the Proposed Rule is finalized, some States or Tribal governments may feel a reevaluation of the scope of their own water resource protection programs is warranted.
The Agencies expect this rulemaking to provide better clarity for the regulated community in terms of the boundaries of federal jurisdiction, and the Sackett decision has likely narrowed the paths for legal challenges. Nevertheless, if the history of WOTUS is any indication, we are still likely to see litigation challenging the Proposed Rule. Previous litigation resulted in a patchwork of WOTUS frameworks across the country.
The Agencies published notice of the Proposed Rule in the Federal Register (the “Notice”) on November 20, which triggered the start of a 45-day public comment period. Comments will be accepted on or before January 5, 2026. This is a key opportunity for interested parties to examine the proposed changes and to submit comments on the Proposed Rule. Also, arguments must generally be made in during the comment period to serve as a basis for challenge in future litigation. If you have questions concerning the proposal or are seeking assistance in preparing comments, please contact MGKF’s Sean Fahy, Todd Kantorczyk or Brenda Gotanda.
