The U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers have unveiled two new supplemental options for redefining “waters of the United States” under the Clean Water Act.
The agencies published the supplemental notice on September 9, 2026, following a deluge of roughly 220,000 public comments on their original November 2025 proposed rulemaking.
A new 30-day comment period has been opened, with a deadline of October 9, 2026, for stakeholders to weigh in on the revised proposals.
The WOTUS definition is critical because it sets the regulatory standards for determining which aquatic features fall under federal jurisdiction under the Clean Water Act.
Central to the new options is a proposed defined term, “perennial,” meaning waters with standing or continuously flowing water every day of the year under ordinary conditions.
This represents a significant tightening compared to the November 2025 framework, which would have allowed waters to qualify as WOTUS by maintaining surface water only during the “wet season.”
The agencies would also extend the perennial concept to wetlands, requiring that they 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.
The supplemental options include two exceptions allowing for temporary interruptions, including anomalous events such as extreme drought, classified as D3 or D4 severity, lasting no more than five consecutive years.
A second exception permits non-anomalous interruptions, such as low tide or a seasonal dry spell, but only if the interruption occurs no more than once per year and for no more than 30 consecutive days.
The agencies acknowledge that the 30-day interruption threshold is not based on a specific, nationally applicable scientific threshold, but was selected as a practical bright-line measure for regulators and landowners.
The agencies also concede that the Supreme Court’s decision in Sackett v. EPA, 598 U.S. 651 (2023), did not expressly call for a continuous surface water connection between jurisdictional waters and wetlands.
However, the agencies argue that prior precedent, namely Rapanos, would require the connection to be exclusively through surface water, underpinning their revised approach.
Analysts note the supplemental options would appear to limit the scope of WOTUS more than the November 2025 proposal, placing jurisdictional thresholds much closer to year-round surface flow.
The agencies acknowledge the stricter standard would eliminate jurisdiction over most of the country’s wetlands, given that many wetlands exist without year-round surface water connections.
At least some states are likely to respond to any federal narrowing of WOTUS by expanding their own jurisdiction over intrastate waters under their independent regulatory authority.