The comment window on the federal government’s narrower definition of “waters of the United States” closed Oct. 9, and construction’s trade groups have now put their positions on the record. The WOTUS supplemental proposal from EPA and the Army Corps of Engineers would limit Clean Water Act jurisdiction to perennial waters and to the slice of a wetland that can’t be told apart from them. For site developers, that’s the line that decides whether a Section 404 permit sits on the critical path.
The National Association of Home Builders said Oct. 14 that it backs the supplemental approach, and the Associated General Contractors of America filed its second round of WOTUS comments this year, asking for a clear, durable rule. Both want more detail than the agencies have written down.
What the supplemental WOTUS proposal changes
The agencies published the supplement Sept. 9 at 91 FR 57286. It sits on top of the November 2025 proposal, which drew more than 220,000 comments and leaned on a “wet season” test. Wet seasons vary by region and are hard to pin down in the field, so the agencies offered a different yardstick.
Under the new option, a “relatively permanent” water is a perennial one: standing or flowing every day of the year under ordinary conditions. It keeps federal status through one ordinary dry spell of up to 30 consecutive days a year, such as low tide or a regular dry season. Extreme or exceptional drought on the U.S. Drought Monitor counts as anomalous, but only for five years. After that, dry becomes the new baseline.
Wetlands get the same treatment. A “continuous surface connection” would require perennial surface water linking the wetland to a jurisdictional water so closely that the boundary is hard to find, and only that indistinguishable portion would be regulated. The agencies also asked whether to delete “adjacent” from the rule altogether.
How a narrower WOTUS rule hits site work and 404 permits
The agencies’ own briefing on the proposal doesn’t put a number on it. It says data limits make the change in scope hard to quantify, then concedes that most intermittent streams and most wetlands now regulated as adjacent would likely fall out. The arid West feels it most, and Section 404 is the program that moves.
Fewer federal waters means fewer individual permits, fewer jurisdictional determinations and less mitigation to buy. It doesn’t mean no permits. States such as California and Washington regulate waters on their own terms, and a federal pullback tends to push them to do more. A grading contractor in the Central Valley may not notice much.
NAHB’s requests are practical. It wants the agencies to spell out how droughts, short dry spells and tidal swings will be judged, to decide cases from readily available information, and to evaluate physically separate wetlands one at a time. That’s a request for field rules a consultant can apply on a site walk, not just a definition.
Open questions before a final WOTUS rule
The proposal is silent on transition. Law firm Davis Wright Tremaine noted in a September client alert that it doesn’t address existing jurisdictional determinations, pending permit applications or mitigation already committed. An owner halfway through a 404 permit doesn’t know yet whether a narrower definition helps or just restarts the paperwork.
The 30-day figure is thin ground, too. Harvard’s Environmental and Energy Law Program points out that the agencies call it an administrative convenience rather than a scientific line. That kind of admission tends to get quoted back in litigation.
Every WOTUS rule since 2015 has been challenged in court, and this one won’t be the exception. Until a final rule survives that, current law and permitting obligations stay where they are. Projects that have sat through a state water-quality certification fight already know how long a water permit dispute can hold a schedule.