New Agency WOTUS Proposal Would Eliminate 'Wet Season' Concept

The Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (Corps) have announced a supplemental proposed rule offering a new approach to defining “waters of the United States” (WOTUS) under the Clean Water Act.

The supplemental proposal responds to comments the agencies received on their November 2025 proposed WOTUS rule, particularly concerns surrounding the proposed “wet season” concept. That concept would have allowed waters that flow continuously during the period when precipitation exceeds evapotranspiration, and wetlands with surface water during that period, to qualify for federal jurisdiction.

The new alternative would eliminate the wet-season concept and instead limit jurisdiction to perennial waters. Under the supplemental proposal:

• “Relatively permanent” waters would be limited to perennial bodies of water, meaning those with standing or continuously flowing water every day of the year during ordinary conditions.
• A waterbody could remain relatively permanent if it temporarily dries up because of an extraordinary event, such as a drought.
• A perennial water could also experience one interruption of up to 30 consecutive days during a year because of an ordinary event, such as low tide or a regularly occurring dry spell.
• A wetland would need perennial surface water that is continuously connected to a jurisdictional water, making it difficult to determine where the water ends and the wetland begins.
• Only the portion of the wetland that is indistinguishably part of the jurisdictional water would be federally regulated.

These alternatives would substantially narrow and clarify the circumstances under which seasonal waters and wetlands are federally regulated. The changes could also make jurisdictional determinations more predictable for builders and developers evaluating land and seeking Clean Water Act Section 404 permits.

The agencies emphasized that the supplemental proposal does not withdraw or replace the November 2025 proposal. EPA and the Corps will consider the new alternatives alongside the original proposal and the approximately 220,000 comments already submitted before issuing a final rule.

NAHB has been closely engaged throughout the rulemaking. Members and staff participated in the agencies’ WOTUS listening sessions, submitted written recommendations and met with EPA and Corps leadership to explain how unclear jurisdictional standards delay residential and mixed-use construction and add to housing costs.

After the initial rule was proposed, NAHB members and HBA staff spoke at all three public meetings, emphasizing the importance of clear definitions for:

• “Relatively permanent” and “continuous surface connection,”
• Predictable exclusions and
• A rule firmly grounded in the Supreme Court’s Sackett v. EPA decision.

NAHB encourages the agencies to consider alternatives that eliminate the uncertain wet-season test and more clearly distinguish federally regulated waters from land and features regulated under state or local law. NAHB is reviewing the proposed definitions, including how the perennial-water standard and 30-day exception would work in practice, and will submit comments on behalf of the residential construction industry.

The 30-day public comment period begins today, Sept. 9, following publication in the Federal Register.