The U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers have proposed supplemental definitions that would change which wetlands count as "waters of the United States" (WOTUS) under the Clean Water Act. The proposal builds on the revised WOTUS rule the agencies put forward in November 2025, and the comment period closed October 9.
The new language responds to the Supreme Court's decision in Sackett v. EPA, which limits federal jurisdiction over adjacent wetlands to those with a continuous surface connection to a jurisdictional water. Under the proposal, a continuous surface connection means perennial surface water in a wetland that is continuously connected to the jurisdictional water. Temporary interruptions from events such as drought are allowed, as is a single dry period of up to 30 consecutive days in a given year. "Perennial" and "relatively permanent" are also newly defined.
For the groundwater industry, the proposal does not define groundwater as a water of the United States. Groundwater is already part of the existing definition of a wetland, and in some locations a high water table that reaches the ground surface can feed wetlands that meet the "relatively permanent" test. State streamflow duration assessment methods, which the EPA lists as tools for these determinations, also address the relationship between groundwater and adjacent streams.
The broader concern for NGWA members is what comes next. As federal wetland protections are pulled back, responsibility for those waters is likely to move to the states, and each state may respond differently. The result could be a mismatch of regulations that is harder to navigate for groundwater professionals working in more than one state.
"Wetland protections can and should be examined for how effective they are," said Ben Frech, NGWA government affairs manager. "But we've seen federal regulations get pulled back and passed down to the states before, with varying degrees of success for our industry.
"PFAS is a good example, where the state response turned into a hodgepodge. We don't want to see the same thing happen with wetlands, and NGWA will keep tracking this closely."
NGWA will continue to monitor the rulemaking and share updates with members as the agencies move toward a final rule.