On November 20, 2025, the U.S. Environmental Protection Agency (EPA) and Department of the Army (Agencies) published a proposed rule, “Updated Definition of Waters of the United States” (Proposed Rule). If finalized, the rule would implement the Supreme Court’s decision in Sackett v. EPA, discussed in a prior SPR blog post.

The Agencies note that the Proposed Rule marks a significant departure from the Agencies’ past practice, where “impacts” were considered in defining the scope of “waters of the United States” (“WOTUS”). The Agencies assert that, as a result of the Supreme Court’s decision in Sackett, they will now solely define EPA’s jurisdiction under the Clean Water Act based on “‘the Act’s allocation of authority’ between the Federal Government and the States.”

Proposed Regulatory Text

The Proposed Rule would amend 33 CFR 328 (Army Corps) and 40 CFR 120 (EPA) to redefine WOTUS to include:

(1) traditional navigable waters and the territorial seas (40 CFR 120.2(a)(1), 33 CFR 328(a)(1));

(2) most impoundments of WOTUS (proposed 40 CFR 120.2(a)(2), 33 CFR 328(a)(2));

(3) relatively permanent tributaries of traditional navigable waters, the territorial seas, and impoundments (proposed 40 CFR 120.2(a)(3), 33 CFR 328(a)(3));

(4) wetlands adjacent (i.e., having a continuous surface connection) to traditional navigable waters, impoundments, and tributaries (proposed 40 CFR 120.2(a)(4), 33 CFR 328(a)(4)); and

(5) lakes and ponds that are relatively permanent and have a continuous surface connection to a traditional navigable water, the territorial seas, or a tributary (proposed 40 CFR 120.2(a)(5), 33 CFR 328(a)(5)).

Key Definitions and Interpretations

To implement this new definition of WOTUS, the Proposed Rule defines several new or revised terms:

“Continuous surface connection” is defined to mean ‘‘having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.’’

“Tributary” is defined to mean “a body of water with relatively permanent flow, and a bed and banks, that connects to a downstream traditional navigable water or the territorial seas, either directly or through one or more waters or features that convey relatively permanent flow. A tributary does not include a body of water that contributes surface water flow to a downstream jurisdictional water through a feature such as a channelized non-jurisdictional surface water feature, subterranean river, culvert, dam, tunnel, or similar artificial feature, or through a debris pile, boulder field, wetland, or similar natural feature, if such feature does not convey relatively permanent flow. When the tributary is part of a water transfer (as that term is applied under 40 CFR 122.3) currently in operation, the tributary would retain jurisdictional status.”

“Relatively permanent” is defined to mean ‘‘standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.’’

Although not defined in the Proposed Rule, the Agencies assert the below terms and phrases contained within this definition are meant to encompass specific meanings.

• ‘‘At least during the wet season’’ is intended to include “extended periods of predictable, continuous surface hydrology occurring in the same geographic feature year after year in response to the wet season.”
• ‘‘Standing” bodies of surface water are meant to encompass “lakes, ponds, and similar features that have standing water year-round or at least during the wet season and that are part of the tributary system.”
• ‘‘Continuously flowing’’ waterbodies are meant to encompass streams, rivers, ditches, and similar features considered under the WOTUS tributaries category.

Removal of “Interstate Waters” as a Standalone Category

The Agencies propose removing “interstate waters” as a separate category of WOTUS (currently included in 40 CFR 120.2(a)(1)(iii) and 33 CFR 328.3(a)(1)(iii)). The Agencies claim such removal is necessary because the “interstate waters” category can encompass bodies of water that are not “relatively permanent, standing, or continuously flowing or that are not themselves connected to a downstream traditional navigable water or the territorial seas, either directly or through one or more waters or features that convey relatively permanent flow.” Under the Proposed Rule, interstate waters would therefore only be ‘‘waters of the United States’’ if they fall within another jurisdictional category in the WOTUS new definition.  Based on similar reasoning, the Proposed Rule would also delete “interstate” from the WOTUS category for lakes and ponds (40 CFR 120.2(a)(5) and 33 CFR 328(a)(5)).

Revised Exclusions and New Groundwater Exclusion

The Proposed Rule revises three of the eight exclusions from WOTUS (Water Treatment Exclusion: 40 CFR 120.2 (b)(1) and 33 CFR 328.3(b)(1); Prior Converted Cropland Exclusion: 40 CFR 120.2(b)(2) and 33 CFR 328.3(b)(2); and Ditch Exclusion: 40 CFR 120.2(b)(3) and 33 CFR 328.3(b)(3)) and adds a new explicit exclusion for “groundwater.”  These exclusions would not apply to traditional navigable waters and the territorial seas.

Anticipated Impacts of the Proposed Rule

The Agencies anticipate that the Proposed Rule would result in an increase in non-jurisdictional findings in approved jurisdictional determinations (AJDs) compared to prior regulations and practice, and that fewer waters and wetlands would fall within the scope of the CWA. The Agencies predict that the Section 404 permitting program will be most impacted by the Proposed Rule, with projected reductions in the number of permits and required mitigation relative to the current regulations. However, the Agencies note that States and Tribes may choose to expand their own regulatory programs to include waters excluded from federal jurisdiction.

AJDs and permits issued under a previous WOTUS definitions will still be considered valid and would not necessarily be reopened if the Proposed Rule is adopted, unless requested by the landowner or applicant. Going forward, when making federal jurisdictional determinations regarding WOTUS, the Agencies have stated that they will make non-jurisdictional determinations if the agencies do not have adequate information to demonstrate that a water meets the new WOTUS jurisdictional standards.

Although the Proposed Rule is intended to “provide greater regulatory certainty and increase . . . predictability and consistency,” past revisions to the WOTUS definition have shown that we can expect increased litigation over the boundaries of federal and state jurisdiction and over the interpretation of the new definitions. Technical delineation by wetlands consultants is likely to become more complex and critical, and increased regulation by states and tribes may create new regulatory uncertainty.

Opportunities for Public Comment

In addition to seeking comments on the changes outlined above, the Agencies also request input on topics related to the Proposed Rule but that are not explicitly addressed in the proposed regulatory text. The regulatory community should consider commenting on these additional items to ensure all key issues are addressed during the public comment period. Such items include:

1. Whether “impacts” should be considered in determining CWA jurisdiction.
2. Whether to adopt an alternative approach to determining if a body of water meets the definition of “relatively permanent waters,” by using minimum flow volume thresholds, minimum flow duration metrics, or other bright line metrics set by region.
3. Whether to define ‘‘wet season’’ in the regulatory text, and whether the Agencies should adopt an alternative approach to implementing ‘‘wet season’’ for continuous surface connection by requiring surface water inundation for at least 90 or 270 days.
4. Whether an entire wetland would be considered ‘‘adjacent’’ if at least part of the wetland demonstrates a continuous surface connection to a jurisdictional water body during the wet season or whether, as proposed, only a portion of the wetland would be considered adjacent.
5. Whether the Agencies should adopt an alternative approach whereby wetlands, lakes, and ponds would have a ‘‘continuous surface connection’’ only if they abut, e., touch, a jurisdictional water and have a continuous surface water connection to that water, with continuous surface water connection meaning the perennial (year-round) presence of surface water.

The 45-day comment period closes January 5, 2026. Members of the public can submit comments here. Additional supporting material is available here.