WOTUS Could Narrow Again: What It Could Mean for Foundry Permitting.
EPA and Army Revisit WOTUS Definition
Federal agencies are seeking additional input on narrower alternatives that could further limit which streams and wetlands fall under Clean Water Act jurisdiction.
The Environmental Protection Agency (EPA) and Department of the Army have reopened a key portion of their proposed definition of “waters of the United States” (WOTUS), seeking public comment on alternatives that could further limit which streams and wetlands are subject to federal Clean Water Act jurisdiction. The supplemental proposal was published September 9, 2026.
What You Need to Know
EPA and the Army are considering additional, narrower alternatives for defining “relatively permanent” waters and determining when wetlands have a continuous surface connection to jurisdictional waters.
The final WOTUS definition helps determine when federal Clean Water Act requirements may apply to construction, facility expansion, earthmoving, discharges and other activities near covered waters.
The public comment period on the supplemental proposal closes October 9, 2026.
The Rulemaking Follows the Sackett Decision
The agencies’ November 2025 proposal sought to align the WOTUS definition with the Supreme Court’s 2023 decision in Sackett v. EPA.
That decision held that adjacent wetlands fall within the Clean Water Act only when they have a continuous surface connection to covered waters, making it difficult to determine where the water ends and the wetland begins.
The 2025 proposal would define “relatively permanent” waters as bodies with standing or continuously flowing water year-round or at least during the wet season. It also would require an adjacent wetland to abut a jurisdictional water and contain surface water at least during the wet season.
Agencies Consider Narrower Alternatives
The supplemental proposal presents additional alternatives that would replace the earlier “wet season” approach with more restrictive standards for both relatively permanent waters and wetlands with a continuous surface connection.
One alternative would generally limit “relatively permanent” waters to those containing standing or continuously flowing water every day of the year under ordinary conditions, while allowing a single regularly occurring interruption of up to 30 consecutive days.
Another alternative would require a wetland to contain perennial surface water continuously connected to a jurisdictional water, again generally allowing only a single interruption of up to 30 consecutive days.
Only the portion of a wetland that is effectively indistinguishable from the jurisdictional water would be covered. These alternatives would exclude many intermittent streams and seasonally connected wetlands that could satisfy broader standards.
What This Could Mean for Foundries
The scope of WOTUS can have practical implications for facility projects involving land disturbance, drainage, wetlands or nearby waterways. Foundries planning expansions or site improvements may want to pay particular attention to:
Projects involving earthmoving, grading or development near streams and wetlands may be affected by where federal jurisdiction ultimately begins and ends.
A narrower final definition could reduce the number of waters and wetlands subject to federal Clean Water Act permitting requirements.
The rule could affect how manufacturers evaluate environmental conditions and permitting needs before acquiring, modifying or expanding property.
A change in federal jurisdiction does not eliminate state wetland, water-quality or permitting requirements that may apply independently.
What Comes Next
EPA and the Army are specifically requesting comments on whether the proposed 30-day thresholds are workable and consistent with Sackett.
The agencies will consider feedback on the supplemental alternatives alongside comments received on the original 2025 proposal as they develop the final WOTUS definition.
Key Dates
Supreme Court issues its decision in Sackett v. EPA.
EPA and the Army publish their proposed updated WOTUS definition.
Supplemental proposed rule is published with additional regulatory alternatives.
Public comment period on the supplemental proposal closes.
Review EPA’s official WOTUS rulemaking materials and supplemental proposal.
Review the EPA ProposalStay Ahead of What Comes Next
The Foundry Brief tracks legislative, regulatory and trade developments affecting the metalcasting industry and helps NFFS members understand what they could mean for business.
Register for the Next Foundry Brief Live Forum