On September 9, the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers published a Supplemental Notice of Proposed Rulemaking (SNPRM) seeking comment on proposed additional revisions to the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). This SNPRM builds on the agencies’ November 2025 Notice of Proposed Rulemaking (NPRM), covered in a prior SPR blog post.

The proposed rules are intended to provide greater regulatory certainty and increase CWA program predictability and consistency by clarifying the definition of WOTUS following Sackett v. Environmental Protection Agency. The Supreme Court in Sackett held that federal jurisdiction under the CWA extends only to those wetlands with a “continuous surface connection” to a “relatively permanent body of water connected to traditional interstate navigable waters.”

November 2025 NPRM

As relevant to the SNPRM, the November 2025 NPRM defined “continuous surface connection” as “having surface water at least during the wet season and abutting (i.e. touching) a jurisdictional water.” The NPRM also defined “relatively permanent” 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.” The agencies received approximately 220,000 comments on the November 2025 NPRM, with commenters expressing differing views on the proposed “wet season” approach and proposing alternative methods for defining “relatively permanent” waters and “continuous surface connection” wetlands. SPR’s prior blog post provides additional detail on the 2025 NPRM.

September 2026 SNPRM

In the 2026 SNPRM, the agencies are seeking comment on supplemental regulatory options for the definitions of “relatively permanent” and “continuous surface connection.” The agencies are not proposing additional changes to other portions of the November 2025 NPRM, including the exclusions for waste treatment systems, prior converted cropland, ditches, and groundwater.

“Relatively Permanent” Definition

The SNPRM seeks comment on a supplemental option that would define “relatively permanent” to mean “perennial bodies of water.” The agencies propose defining “perennial” as “having standing or continuously flowing water every day of the year during ordinary conditions.” Under the proposed definition, a water body would not lose its relatively permanent status if it dries up as a result of anomalous events such as drought or dry spell, or if it dries up for no more than a single period of up to 30 consecutive days in a given year due to non-anomalous events, such as low tide or a regularly occurring dry spell.

“Continuous Surface Connection” Definition

The SNPRM also seeks comment on an alternative definition of “continuous surface connection.” The agencies propose that “continuous surface connection” mean “perennial surface water in a wetland that is continuously connected with the surface water in the jurisdictional water such that it is difficult to determine where the jurisdictional water ends and the wetland begins.” As with the proposed definition of “relatively permanent,” the agencies would allow limited interruptions resulting from anomalous events such as drought or dry spells, and temporary interruptions of up to 30 consecutive days caused by non-anomalous events.

The agencies emphasize that, in order to implement Sackett’s mandate, only the portion of the wetland that is “indistinguishably part of the jurisdictional water” would be jurisdictional. The agencies are also soliciting comments on whether the terms “adjacent” or “abutting” should be removed from the definition of “continuous surface connection” in favor of the concept that only wetlands that are “indistinguishably” part of a jurisdictional water constitute WOTUS.

Impacts

While the proposed definitions may or may not provide increased certainty for a landowner, it is undisputed that the proposal would narrow federal CWA jurisdiction further than the regulatory framework provided in the 2025 NPRM. According to the agencies, most intermittent streams would likely not satisfy the proposed “perennial” standard, with the greatest difference in regions where intermittent streams drive much of the hydrology, particularly in the arid West.

The agencies also stated that the majority of wetlands that are jurisdictional as adjacent wetlands under current regimes would not satisfy the supplemental definition of “continuous surface connection,” as most wetlands do not contain “perennial” surface water. The agencies anticipate that the CWA section 404 program would likely see the most programmatic changes under the SNPRM options, with projected reductions in permit numbers and mitigation requirements.

Comments on the SNPRM must be received on or before October 9, 2026.