Wake Me Up When September Ends: More WOTUS Changes Coming

Key Takeaways

• The U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (the Corps) have offered two “supplemental options” for the regulatory definitions provided in their November 2025 notice of proposed rulemaking to redefine the Clean Water Act’s jurisdictional trigger, “waters of the United States” (WOTUS). 
• The agencies have opened an additional 30-day comment period that closes on October 9, 2026.
• At least some states will likely respond by expanding state jurisdiction over intrastate waters under their independent regulatory authority

Background

Following a deluge of roughly 220,000 public comments on their November 2025 proposal, EPA and the Corps are back at it again—this time, offering two new options for their still-pending proposed WOTUS rule. As a reminder, the WOTUS definition sets the regulatory standards for determining which aquatic features are subject to federal jurisdiction under the Clean Water Act.

The agencies’ proposal, published September 9, 2026, asks commenters to consider the potential utility of a new defined term, “perennial,” to help clarify the terms “relatively permanent” waters and “continuous surface connection” instead of the “wet season” concept they initially identified. The supplemental notice, however, provided that the November 2025 framework remains in play alongside this new alternative.

Key Proposed Further Changes

1. New “Perennial” Concept for “Relatively Permanent” Waters and “Continuous Surface Connection” to Wetlands

The agencies’ supplemental options propose defining “relatively permanent” waters with a new term, “perennial,” meaning waters with standing or continuously flowing water every day of the year under ordinary conditions. The agencies would also extend the “perennial” concept to determining the jurisdictional status of wetlands based on a “continuous surface connection.” Specifically, it would require that wetlands connect to a jurisdictional water via perennial surface water such that it is difficult to determine where the jurisdictional water ends and the wetland begins. Both alternatives are material departures from the November proposal, which suggested waters would qualify as WOTUS so long as they at least maintain surface water during the “wet season” and extended to adjacent wetlands without expressly requiring the “continuous surface connection” be a continuous surface water connection. In either case, the agencies’ year-round standard would allow for two exceptions accommodating certain temporary interruptions.

First, waters and wetlands could remain jurisdictional when anomalous events cause the surface water connection to dry up. Examples include drought or an unusual dry spell. For drought, the agencies propose treating only extreme (D3) and exceptional (D4) droughts as anomalies. Further, droughts cannot last more than five consecutive years; beyond that, the drought becomes the “new normal,” and jurisdictional coverage ends.

Second, if interruption is due to non-anomalous events, jurisdiction survives only if the interruption occurs no more than once per year and for no more than 30 consecutive days. Examples would be low tide or a seasonal, short-term dry spell. The “single period” limitation would appear to disqualify a waterbody that ordinarily loses flow twice in one year, even if neither interruption lasts 30 days. For example, two separate 10-day periods without flow would make the surface water intermittent or ephemeral under the supplemental approach. On the other hand, surface water that predictably dries for 30 consecutive days each August could still qualify as perennial.

Specific to wetlands, the agencies are separately requesting comment on whether “adjacent” or “abutting” should remain operative concepts at all, or whether the regulations should instead cover wetlands when they are indistinguishably part of an otherwise jurisdictional water.

2. Caveats

The agencies acknowledge that a 30-day interruption period is not based on a specific, nationally applicable scientific threshold. Rather, they selected roughly one month as a bright-line measure of a “temporary” interruption that would be predictable, transparent, and easier for landowners and regulators to administer. They also concede that the Supreme Court’s recent decision in Sackett v. EPA, 598 U.S. 651 (2023) (Sackett II), did not expressly call for a continuous surface water connection between jurisdictional waters and wetlands; however, the agencies posit that prior precedent (namely Rapanos) would require the connection be exclusively through surface water.

3. Renewed Call for Input on Methods

The agencies have reiterated their interest in comments discussing tools and methodological approaches for defining the “wet season” or what constitutes “perennial.” The supplemental notice promises that the agencies will continue to rely on remote and field-based tools.

4. Even Narrower Than Before?

The supplemental options would appear to limit the scope of WOTUS more than the agencies’ original proposal last November because they would place jurisdictional thresholds much closer to year-round surface flow. Intermittent waters that could satisfy a wet-season standard would fall outside the supplemental options’ scope. And wetlands would need more than mere physical contact with a jurisdictional water, which would exclude wetlands that can exist without year-round surface water—something the agencies acknowledge would eliminate jurisdiction over most of the country’s wetlands.

Next Steps

• Assess jurisdictional determinations that impact your regulatory obligations and consider what changes, if any, might result from the new criteria.
• Interested stakeholders should prepare comments and monitor the progress of this rulemaking process. The 30-day comment deadline ends October 9, 2026.

Beveridge & Diamond advises clients on the full spectrum of Clean Water Act issues, including jurisdictional determinations, permitting, enforcement risk, and litigation. Our Water practice helps navigate the complexities of federal and state regulatory interpretations as agencies and courts continue to reshape the scope of WOTUS. For more information, please contact the authors.