EPA and Army float year-round-flow test for federal waters and wetlands; comments on supplemental WOTUS options due Oct. 9

“Having standing or continuously flowing water every day of the year during ordinary conditions.” That is how the Environmental Protection Agency (EPA) and the Department of the Army propose to define “perennial” in a supplemental notice published Sept. 9, and under the main option it offers, a stream or wetland would have to meet that test, with narrow exceptions, to fall under federal Clean Water Act permitting^[1]. Comments are due Oct. 9^[1].

The notice does not replace the agencies’ November 2025 proposal to redefine “waters of the United States,” or WOTUS. It adds options for the final rule to choose from, and the agencies say they will weigh both sets together^{[1, 3]}. For farmers and ranchers with seasonal creeks, draws and wet ground near streams, the gap between the two is the difference between a water that flows “at least during the wet season” and one that flows nearly all year.

The details: what changes from the 2025 proposal

The November 2025 proposal defined “relatively permanent” waters as those standing or continuously flowing “year-round or at least during the wet season,” and defined a wetland’s “continuous surface connection” as having surface water at least during the wet season and abutting, or touching, a jurisdictional water^[2]. That proposal drew about 220,000 comments between Nov. 20, 2025, and Jan. 5, 2026^{[1, 3]}. Many asked for clarification; some said it went beyond what the Supreme Court required, and others said it did not go far enough^[1].

The supplemental option drops the wet season. “Relatively permanent” would mean “perennial bodies of water”^[1]. Two exceptions keep a water in:

• Anomalous events. A water does not lose its status if it dries up because of drought or an unusual dry spell^[1]. The agencies are considering counting only extreme (D3) and exceptional (D4) drought on the U.S. Drought Monitor, and only for up to five continuous years, after which drier conditions would be treated as the new normal^[1]. The five years match the expiration period of an approved Army Corps of Engineers jurisdictional determination under Regulatory Guidance Letter 05-02^[1].
• Ordinary, predictable interruptions. Low tide or a regularly occurring dry spell does not break jurisdiction if the water is dry for no more than “a single period of up to 30 consecutive days in any given year”^[1]. Two separate 10-day dry stretches in an ordinary year would disqualify a water, because the allowance covers one period only^[1]. The year does not have to follow the calendar; it could run September to August^[1].

The agencies give their own examples. A stream that goes dry for 30 straight days every June would stay jurisdictional^[1]. A stream that is ordinarily dry from June through August, about 90 days, would not^[1]. They call the 30-day line a bright line chosen to be “predictable, transparent, and easy to administer,” while conceding there are no precise, scientifically grounded, nationally consistent time limits for such interruptions^[1]. They also ask whether perennial should instead carry the 2020 Navigable Waters Protection Rule wording, “surface water flowing continuously year-round”^[1].

Wetlands get the same treatment. A “continuous surface connection” would mean perennial surface water in the wetland, connected to the surface water of a jurisdictional water so that it is difficult to tell where one ends and the other begins, with the same drought and 30-day allowances^[1]. Only the part of a wetland that meets that test would be jurisdictional^[1]. A second alternative would delete the term “adjacent” from the regulations and cover only wetlands that are “indistinguishably part of” a jurisdictional water^[1].

Both options lean on the Supreme Court’s May 25, 2023, decision in Sackett v. EPA, which said the agency “must provide clear evidence that it is authorized to regulate in the manner it proposes” and acknowledged that “temporary interruptions in surface connection may sometimes occur because of phenomena like low tides or dry spells”^[5]. The agencies argue a landowner could tell whether the test is met “simply by observation,” without hiring a consultant^[1].

In the field: who would see the biggest change?

The farm-specific pieces of the 2025 proposal are untouched. The supplemental notice makes no change to the proposed exclusions for prior converted cropland, ditches excavated entirely in dry land, or groundwater, including groundwater drained through subsurface systems^[1]. Under the 2025 text, cropland drained or manipulated for farming before Dec. 23, 1985, keeps the prior converted cropland exclusion unless it goes five years without agricultural use and reverts to wetland, and EPA and the Corps would recognize designations made by the Secretary of Agriculture^[2]. USDA’s own wetland determinations, which carry weight under farm program rules, were the subject of this site’s coverage in July.

The change falls on streams and wetlands that are not excluded. The agencies expect that “most intermittent streams” would not meet the supplemental definition, though many count as relatively permanent today^[1]. They write that “the majority of wetlands” now jurisdictional as adjacent wetlands would not meet the new connection test, “as most wetlands do not contain perennial surface water”^[1].

Region matters. The agencies expect “the arid West in particular” to see a significant reduction in federal waters^[1]. For scale, the National Hydrography Dataset maps about 1.3 million miles of perennial streams and 3.5 million miles of intermittent streams in the contiguous states, roughly 21% and 55% of mapped stream miles^[1]. The agencies caution that the dataset does not show which waters are federally regulated now and could not be used to estimate how many miles would change^[1].

The section 404 dredge-and-fill permit program would see the largest change, with fewer permits and less required mitigation^[1]. The agencies say both the cost savings and the forgone benefits are larger under the supplemental package than under the 2025 proposal^[1]. They name mitigation banks and restoration firms as the sectors likely most affected, and say businesses that cater to hunters and anglers could also be hurt^[1].

Waters that fall out of federal jurisdiction are not unregulated. EPA’s release notes that they remain subject to state, Tribal and local law^[3]. The agencies acknowledge, though, that some states may need to spend considerable resources to build their own programs, and that some state laws bar regulation stricter than the federal rules^[1].

Who supports the options, and who objects

EPA Administrator Lee Zeldin said in the Sept. 4 announcement that “the EPA’s goal is a durable WOTUS definition that follows the law and ends burdensome regulatory uncertainty”^[3]. Adam Telle, the Assistant Secretary of the Army for Civil Works, said “the Supreme Court’s Sackett decision delivered the certainty our nation has been seeking for decades” and that the Corps “stands ready to implement this rule once final”^[3].

American Farm Bureau Federation President Zippy Duvall said in a statement reported by DTN that the rule “provides a clear understanding of federal jurisdiction, which is critical for farmers who may face severe penalties or even jail time for unknowingly violating the law”^[4]. He added that the group was still reviewing the details^[4].

Opposition so far appears in the record the agencies summarized. Commenters on the 2025 proposal who opposed it said it “would increase regulatory uncertainty and adversely impact water quality”^[1]. Some asked that intermittent streams stay under federal jurisdiction, and some argued ephemeral streams should be covered “due to the many functions such streams serve”^[1]. Others said fixed flow-duration thresholds “are not scientifically grounded,” and one argued that a surface-water connection requirement would cover only a small fraction of non-tidal wetlands^[1]. Some commenters said the connection test would effectively override the long-standing regulatory definition of “wetlands” without proper notice^[1]. The agencies, for their part, say reliance on past practice cannot justify keeping a definition that conflicts with Sackett^[1].

The agencies describe the background plainly: the past 11 years brought five rule revisions, a major Supreme Court decision, a field memorandum and a stream of lower-court rulings^[1].

What to watch: Oct. 9 and the final rule

Comments are due Oct. 9 under Docket EPA-HQ-OW-2025-0322^[1]. The agencies ask for views on the 30-day limit, the five-year drought cap, the D3 and D4 drought cutoff, tools for identifying dry spells, and whether “adjacent” belongs in the rule at all^[1]. People who commented on the 2025 proposal should not resubmit those comments^[1].

Until a final rule is issued, the current definitions stay in place^[1]. The agencies say they will take final action after considering comments on both notices^{[1, 3]}. Neither document gives a date.