WOTUS Proposed Rule Second Comment Period Ends October 9, 2026

The United States Environmental Protection Agency (“EPA”) and the United States Army Corps of Engineers (“Corps”) recently published a second proposed rule updating the definition of “waters of the United States” (“WOTUS”). This alert briefly describes the proposed changes, why it happened, and next steps.

Why a Second Proposed Rule

In a previous alert, we discussed the background on why the Trump administration proposed to change the definition of WOTUS in 2025. Since that time, the EPA and the Corps have received over 220,000 public comments. Many comments pointed to ambiguity in the proposed rule and asked for additional clarification. This second proposed rule attempts to provide clarity on three specific definitions.

Proposed Rule

This second proposed rule largely consists of three updates: it (1) revises the definition of “relatively permanent,” (2) revises the definition of “continuous surface connection,” and (3) defines “perennial.”

“Relatively Permanent”

The 2025 proposed rule defined “relatively permanent” as “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.” Many comments pointed out how the last portion of the definition of “relatively permanent” is ambiguous. What is the “wet season”? When does it start? When does it stop? What about during an unusually wet year? What about during a drought?

In response, the EPA and the Corps now propose to update the definition of “relatively permanent” to be “perennial bodies of water.” Still not completely clear, the definition provides additional detail and goes on to say:

A body of water does not lose its relatively permanent status if it dries up as a result of anomalous events such as drought or dry spell. A body of water also does not lose its relatively permanent status if it dries up for no more than a single period of up to 30 consecutive days in any given year as a result of non-anomalous events resulting in a temporary interruption such as low tide or a regularly occurring dry spell.

The EPA and the Corps are asking for comments on (1) if they should use a five-year timeframe for interpreting “drought,” (2) if they should use a timeframe other than 30 consecutive days for “non-anomalous events resulting in a temporary interruption such as low tide or a regularly occurring dry spell,” and (3) tools they can use to determine “drought or dry spell” and “low tide” conditions.

“Continuous Surface Connection”

The 2025 proposed rule proposed to define “continuous surface connection” as “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” Many comments, pointed out, again, how “wet season” is not clear.

In response, the EPA and the Corps propose to update the definition of “continuous surface connection” to be “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.” This updated definition clarifies and narrows the scope to wetlands connected to jurisdictional waters. But the definition goes further and provides:

Temporary interruptions in the surface water connection may occur as the result of anomalous events such as drought or a dry spell. A temporary interruption in the surface water connection lasting for no more than a single period of up to 30 consecutive days in any given year may also occur as a result of non-anomalous events such as low tide or a regularly occurring dry spell.

These additional details align with the EPA’s and the Corps’ proposed definition of “relatively permanent.” The scope for both definitions is clear that wetlands with interruptions between wetlands and jurisdictional waters due to anomalies or normal events that last for less than 30 days are still WOTUS.

“Perennial”

Because the EPA and the Corps use the term “perennial” in their proposed definitions of “relatively permanent” and “continuous surface connection,” they also propose a separate definition of “perennial” as “having standing or continuously flowing water every day of the year during ordinary conditions.”

The EPA and the Corps also request comment on whether “perennial” should instead be defined as “surface water flowing continuously year-round.” This alternative definition would be consistent with the 2020 rule, which was vacated by two district courts and replaced by the 2023 rule.

Next Steps

This proposed rule was published in the federal register on September 9, 2026. Comments must be received by October 9, 2026. Comments can be submitted here. If you or a company that you know are affected by this proposed rule, please consider submitting comments. Alternatively, feel free to reach out to an environmental attorney at Stites & Harbison. We would be happy to help you draft comments or submit comments on your behalf. As always, we will continue to monitor and provide updates on the latest federal environmental regulations.