What to Know
- The EPA and Army Corps of Engineers proposed narrowing the WOTUS definition on September 9, 2026, replacing the “wet season” standard with a stricter “perennial” flow requirement.
- Under the proposed WOTUS rule, a wetland would only be jurisdictional if it maintains a continuous perennial surface water connection to a jurisdictional water, with limited drought exceptions.
- Stakeholders who support or oppose the proposed changes to Clean Water Act jurisdiction have until October 9, 2026 to submit comments — litigation over the final rule is widely expected.
Introduction
On September 9, 2026, the US Army Corps of Engineers (the Corps) and the US Environmental Protection Agency (the EPA) released a Supplemental Notice of Proposed Rulemaking that proposes further revisions to the regulatory definition of “waters of the United States” — a key phrase determining the Clean Water Act’s reach—beyond the changes already proposed in the November 2025 Notice of Proposed Rulemaking (the November 2025 NPRM). These newly proposed revisions reflect the agencies’ engagement with over 220,000 comments received on the November 2025 NPRM and what the agencies explain as their intent to more closely align regulations for Clean Water Act jurisdiction with statutory text and the US Supreme Court’s 2023 decision in Sackett v. EPA.
Bracewell’s prior summary of the November 2025 NPRM is available here.
Proposed Changes
In the Supplemental Notice of Proposed Rulemaking (the SNPRM), the agencies propose changes that would provide additional detail regarding what waters constitute “relatively permanent” waters and what constitutes a “continuous surface connection” for purposes of jurisdiction over wetlands.
- Relatively Permanent Waters. In the November 2025 NPRM, the agencies proposed to define “relatively permanent” — an important phrase used in identifying jurisdictional waters — as containing standing or flowing water year-round, or “at least during the wet season.” The SNPRM now proposes to abandon the “wet season” concept, instead defining “relatively permanent” as “perennial,” meaning that standing or flowing water would be present every day of the year “with certain exceptions affecting year-round flow.” A stream, for example, could remain jurisdictional after drying up only in the case of:
- “Non-anomalous events” like predictable low tide or regularly recurring dry spells, provided that a single interruption does not exceed 30 consecutive days a year.
- “Anomalous events” like significant droughts. The agencies propose to limit anomalous events to extreme (D3) or exceptional (D4) droughts on the US Drought Monitor scale. There would be no consecutive or daily limit on an interruption in flowing or standing water, but a drought lasting continuously for more than five years would become the “new normal,” and the stream would lose jurisdictional status. Note that a less-severe drought on the US Drought Monitor scale would apparently be treated as a “non-anomalous” event with its lower thresholds for loss of jurisdictional status.
- Jurisdictional Wetlands. The SNPRM also proposes to replace the November 2025 NPRM’s “wet season” touching/abutting test for adjacent wetlands with a requirement that the wetland maintain a perennial surface water connection to a jurisdictional water. The same standards for interruptions (i.e., non-anomalous events and anomalous events) would apply to the surface water connection. Only the portion of the wetland that is “indistinguishable” from the jurisdictional water — because of the perennial surface water connection — would be a jurisdictional wetland.
- The agencies are also soliciting public comment on another change: eliminating the terms “adjacent” and “abutting” and relying solely on the indistinguishability test. Under the indistinguishability test, a wetland would be jurisdictional only where a continuous surface water connection makes it impossible to tell where a jurisdictional water ends and the wetland begins.
Implications
The agencies explain that they propose these bright-line tests as another option for consideration in an effort to make Clean Water Act jurisdiction clearer and more predictable, with consistent national application. Although the agencies anticipate that some aquatic features may lose federal protection under the proposal, the agencies also express their view that the states will be able to protect any features or wetlands through state law and regulation.
The proposed rule may raise questions regarding implementation if finalized as proposed, although the agencies’ goal is to facilitate jurisdictional assessments without the need to hire expert consultants. With respect to “relatively permanent,” the agencies explain it “could further simplify implementation” because if landowners “see that waters dry up in circumstances other than during anomalous events … or non-anomalous events … they would know those waters would not be jurisdictional … by simple observation, without the need for any further analysis or professional consultation.” The agencies go on to describe tools that could be used to undertake this analysis and ask for comments on available resources. Interested stakeholders may wish to comment on this proposed approach which may suggest a need for ongoing “observation” as a basis to assess jurisdiction at any given time although the agencies expressly disclaim the need for “continuous monitoring.” With respect to “continuous surface connection,” the agencies use a similar rationale to explain that “members of the public” could assess jurisdiction through observation without the need for “professional consultation.”
The final rule is sure to be litigated, whatever specific definition the agencies promulgate in the end. But opponents of the final rule are especially likely to focus their challenges on bright-line tests in a final rule and claim a lack of scientific support, as they have in earlier rounds of litigation challenging attempts at a WOTUS definition. Although the agencies frame the SNPRM as a consistent extension of Sackett v. EPA and applicable holdings from related cases, if the proposal is finalized, opponents may argue that the agencies’ definition is too narrow a reflection of the Clean Water Act’s intended reach, as prior challenges argued that broader definitions went too far.
Supporters of the agencies’ general approach here may be well-served by submitting additional comments on the SNPRM to inform the agencies of their views as the agencies work to promulgate a clear and durable framework for Clean Water Act jurisdiction. Comments are due on or before October 9, 2026.