New WOTUS Rule: Déjà Vu All Over Again?

On November 20, 2025, EPA and the U.S. Army Corps of Engineers (“the agencies”) published a proposed rule revising the regulatory definition of “waters of the United States” subject to the agencies’ jurisdiction under the Clean Water Act (“CWA”).[1] The proposed rule is the latest attempt by the Executive Branch to resolve by rulemaking the perennial legal uncertainty regarding the limits of federal jurisdiction under the CWA. In this latest effort, the agencies’ stated goal is to align their jurisdiction over navigable waters with the Supreme Court’s 2023 decision in Sackett v. EPA. That decision limited federal jurisdiction to those “relatively permanent, standing or continuously flowing bodies of water ‘forming geographic[al] features’ that are described in ordinary parlance as ‘streams, oceans, rivers, and lakes.’”[2]

In general, the proposed rule:

• eliminates the agencies’ automatic jurisdiction over interstate waters and requires that such waters must independently meet the definition of “waters of the United States”;
• clarifies exclusions for wastewater treatment systems, prior converted agriculture, and ditches, and codifies a groundwater exclusion for the first time; and
• defines terms necessary to incorporate the Sackett decision such as “relatively permanent,” “tributary,” and “continuous surface connection.” 

But the attempt to once again set out in rulemaking a clearer definition of “waters of the United States” may create more uncertainty than answers for regulated entities and almost certainly will lead to years more of litigation. All of that will kick off after comments on the rule are filed. The deadline is January 5, 2026. 

Background to Sackett

The CWA prohibits discharges of pollutants into “navigable waters,” which are defined as “waters of the United States, including territorial seas.”[3]  The Act does not further define “waters of the United States.” Since the CWA’s inception, uncertainty about the meaning of “waters of the United States” has confounded regulators and regulated parties alike. The agencies historically asserted broad authority over waters and wetlands based on this ambiguity. But the Supreme Court has interpreted the term more restrictively. It has recognized that “waters of the United States” includes adjacent wetlands, but not isolated wetlands.[4] In Rapanos v. United States, a fractured (4-1-4) Court rejected the agencies’ assertion of jurisdiction over wetlands located near man-made ditches that were ultimately connected to traditional navigable waters. Justice Kennedy’s decisive concurring opinion argued for defining the term to include waters or wetlands that have “a ‘significant nexus’ to waters that are or were navigable in fact or that could reasonably be made so.”[5] The plurality opinion by Justice Scalia argued for a definition of “relatively permanent, standing or continuously flowing bodies of water ‘forming geographic features’ that are described in ordinary parlance as ‘streams[,] . . . oceans, rivers, [and] lakes.’”[6]  Following Rapanos, most courts took the position that if a water body or a wetland met either the “significant nexus” test or the “relatively permanent” test, then the agencies had jurisdiction.

Seventeen years after Rapanos, in Sackett, a unanimous Supreme Court rejected the “significant nexus” view as unworkable, and the entire Court agreed that the wetlands on the Sacketts’ property were not subject to the agencies’ jurisdiction. The Court concluded that the Rapanos plurality’s interpretation requiring “relatively permanent, standing or continuously flowing bodies of water ‘forming geographic features’ that are described in ordinary parlance as ‘streams[,] . . . oceans, rivers, [and] lakes” was the proper test, and a majority of the Court further held that a continuous surface connection to a “relatively permanent” water body was required for a wetland to be subject to the agencies’ jurisdiction.[7] Justice Thomas’ concurrence would have limited jurisdiction to more traditional navigable waters.[8] Justice Kavanaugh’s concurrence in the judgment argued that adjacent wetlands did not require a “continuous surface connection” to be subject to the agencies’ regulatory authority.[9] No member of the Court quarreled with the “relatively permanent” test for “waters of the United States.”

Ultimately with respect to wetlands, the Court held, “the CWA extends to only those wetlands that are “as a practical matter indistinguishable from waters of the United States.” The Court then proposed a two-part test to determine whether a wetland is jurisdictional: “first, that the adjacent [body of water constitutes] . . . ‘water[s] of the United States,’ (i.e., a relatively permanent body of water connected to traditional interstate navigable waters); and second, that the wetland has a continuous surface connection with that water, making it difficult to determine  where the ‘water’ ends and the ‘wetland’ begins.”[10] 

In light of the Court’s holdings that “waters of the United States” requires a “relatively permanent” water body and that wetlands must have a “continuous surface connection” to a “water of the United States,” the agencies have waded into attempting to define those terms and how they will be applied in the real world. 

The “Wet Season”: The Next Controversy 

Wrestling with Sackett’s holding that “waters of the United States” must be “relatively permanent,” the agencies introduce the concept that water must be continuously flowing “at least during the wet season.” The Court in Sackett, however, did not use the phrase “wet season.” Nor was this concept addressed in Rapanos. 

The Rapanos plurality opinion debated with the dissent over whether “relatively permanent” included “seasonal” rivers. The plurality discussion is found in a footnote:

By describing “waters” as “relatively permanent,” we do not necessarily exclude streams, rivers, or lakes that might dry up in extraordinary circumstances, such as drought. We also do not necessarily exclude seasonal rivers, which contain continuous flow during some months of the year but no flow during dry months—such as the 290–day, continuously flowing stream postulated by Justice STEVENS’ dissent. Common sense and common usage distinguish between a wash and seasonal river. . . . [W]e have no occasion in this litigation to decide exactly when the drying-up of a streambed is continuous and frequent enough to disqualify the channel as a “wate[r] of the United States.” It suffices for present purposes that channels containing permanent flow are plainly within the definition, and that the dissent’s “intermittent” and “ephemeral” streams—that is, streams whose flow is “[c]oming and going at intervals . . . [b]roken, fitful,” or “existing only, or no longer than, a day; diurnal . . . short-lived”—are not.[11]

In Sackett, the Court stated that the Rapanos plurality was “correct” that “waters of the United States” had to be “relatively permanent and continuously flowing or standing,” but the Court did not delve into the Rapanos discussion about seasonal, intermittent and ephemeral streams.

The agencies’ decision to qualify relative permanence by introducing the concept of the wet season is likely to drive a significant number of comments. The agencies recognize this is a new concept in the rules and have specifically requested comments on this topic. Generally, the agencies solicit comments on the workability of the proposed revisions and on alternative approaches that may be clearer and more workable.

The Definition of “Relatively Permanent”: What Is the “Wet Season”?

The proposed rule does not specifically define “wet season.” The agencies suggest that the wet season incorporates times when “average monthly precipitation exceeds average monthly evapotranspiration.”[12] The agencies propose the “at least during the wet season” qualifier as a “bright line” rule that will exclude so-called “ephemeral waters” that flow only in response to single precipitation events (snowfall or rainfall).[13] The addition of the phrase “at least during the wet season” “is intended to include extended periods of predictable, continuous surface hydrology occurring in the same geographic feature year after year,” and the proposed rule requires surface hydrology to be “continuous throughout the entirety of the wet season.”[14] 

The agencies stated that the “wet season” is “easily understood in ordinary parlance and should be implementable by both ordinary citizens and trained professionals,” and that the agencies have “used the concept of the ‘wet season’ for decades to assess water features.”[15] Despite proclaiming that the wet season is easily understood, the agencies acknowledge that wet season will vary across the country and within regions and that determining the scope of the wet season will likely require the use of sophisticated modeling and analysis. 

The agencies acknowledge, for instance, that “surface hydrology may not always exactly overlap with the wet season.”[16] This is especially true where snowpack might accumulate during the wet season but fill channels during the subsequent drier seasons. Additionally, the agencies are not clear on how the “wet season” might vary, not only region to region but within the same region across microclimates. Thus, the agencies seek comments on how the term “wet season” might best be implemented and on the best tools and methods for determining the wet season. The agencies recognize that limiting “relatively permanent” to perennial features would simplify the rule, as landowners that see waters dry up, other than during droughts, would have certainty that such waters are not jurisdictional, simply by observation. The agencies, therefore, ask whether a clearer definition would limit the term “relatively permanent” to perennial waters, or whether “relatively permanent” should include “only waters that have standing or flowing water year-round or that have standing or continuously flowing water at least seasonally (e.g., typically three months).”[17] The agencies also considered, but rejected, approaches such as requiring “minimum flow volume thresholds” or “minimum flow duration metrics (e.g., 30, 90, or 270 days).”[18] While the agencies rejected these approaches on workability grounds, they nonetheless solicit comments on whether requiring a minimum fixed number of days would be more workable. 

Proposed Definition of “Tributary”: Is My Ditch a Tributary? 

The proposed rule defines “tributary” to mean “a body of water with relatively permanent flow, and a bed and bank, that connects to a downstream traditional navigable water or the territorial seas, either directly or through one or more waters or features that convey relatively permanent flow.”[19] The revision proposes to retain the existing practice of considering artificial waterbodies such as ditches, pipes, and culverts as jurisdictional, but limits the consideration to only such features with a relatively permanent flow. Moreover, the proposed rule’s application of the “relatively permanent” standard allows non-jurisdictional water features to connect tributaries as long as such features convey a “relatively permanent” flow. 

The agencies’ requests for comments on the definition of tributary focus on the “relatively permanent” standard and the extent to which man-made features sever jurisdiction.[20] Particularly, the agencies are interested in understanding the conditions described in the proposed definition where the definition excludes a body of water that contributes surface flow to a downstream jurisdictional water but does not convey a “relatively permanent” flow. Alternatively, the agencies request comments on whether additional physical characteristics should be added to the definition and whether the addition of “relatively permanent” is redundant. Finally, the agencies ask whether man-made features should not sever jurisdiction where they convey a “relatively permanent” flow, or whether such features should sever jurisdiction in all cases other than a water transfer. Alternatively, the agencies request comments on an approach where a tributary does not lose its jurisdictional status if it contributes surface water to a downstream jurisdictional water through a non-jurisdictional, man-made feature.

The preamble recognizes that the regulatory status of ditches has traditionally created confusion for agricultural operations, irrigation districts, and municipalities, among others. To provide clarity, the proposed rule excludes from the “waters of the United States” ditches entirely excavated on dry land. The exclusion extends to ditches excavated entirely in uplands, even where such ditches convey a flow that is not relatively permanent but transitions to flow that is. The proposed revision does not specifically define “dry land” or “uplands,” although those terms have historically meant land that does not qualify as wetlands. Ditches constructed to relocate a tributary or excavated in wetlands will not be considered as entirely excavated on dry land and would be assessed under the definition of tributary. The agencies acknowledge that determining whether a ditch was excavated entirely in dry land poses challenges, and they solicit comments on possible methods for making that determination. They also request comments on alternative approaches. One such approach would be to exclude ditches that convey less than a relatively permanent flow of water, irrespective of where or how the ditch was constructed or the purpose it serves. Broader still, the agencies seek comment on an approach that would exclude all non-navigable irrigation and drainage ditches, regardless of whether the ditch conveys a relatively permanent flow or not or whether it was entirely excavated on dry land. 

Proposed Definition of “Continuous Surface Connection”: Are We in a Drought or the Dry Season? 

For a wetland to be considered a jurisdictional water of the United States, it must have a continuous surface connection to a jurisdictional water. The proposed rule defines “continuous surface connection” to mean “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.”[21] Whether a water feature satisfies the definition requires a two-prong test: (1) it must abut a jurisdictional water; and (2) it must have surface water at least during the wet season. Thus, a water feature such as a wetland cannot be jurisdictional if it does not touch a jurisdictional water. While the agencies do not propose to revise the longstanding definition of “wetlands,” wet areas meeting the definition of a wetland would not be jurisdictional unless they satisfied both prongs. Additionally, under the proposed rule, only those portions of a wetland that satisfy both prongs would be jurisdictional waters, “no matter the full delineated scope of the wetland.”[22]

As with the proposed definition of “relatively permanent,” the key standout in the proposed definition is the requirement for a continuous surface connection only during the “wet season.” Sackett proposed no such limitation. Rather, Sackett required the continuous presence of water but for brief periods of interruption such as drought.[23] The proposed rule, instead, by adding in the “wet season” qualifier allows for jurisdiction over wetlands that lack surface water for much or the year. Accordingly, the agencies request comments on whether the addition of the “wet season” aligns with Sackett’s holding and whether wetlands that simply abut a jurisdictional water should be considered “indistinguishable” from surface waters. Alternatively, the agencies ask whether the definition should require a “continuous surface water flow,” to exclude all but perennial wetlands, or putting a day qualification on the length of time in which surface water must be present such 90 or 270 days. While the agencies requests for comments signal their willingness to exclude more wetlands from jurisdiction, they acknowledge that under the proposed definition few wetlands in the arid West would be found to have a continuous surface connection and request comments on the impacts of the proposed rule on such wetlands. 

Looking Forward

The agencies’ attempt to provide clarity by adding the “wet season” into the definition of the “waters of the United States” will be controversial, and commentors will likely debate whether the “wet season” concept conflicts with or faithfully implements the Sackett decision. The proposed rule raises similar questions as to all the agencies’ new definitions of the elements of what constitutes “waters of the United States.”

 If you are interested in commenting on the proposed rule, or otherwise wish to discuss the proposed rule, please contact Brian Daluiso.

[1] 90 Fed. Reg. 52498 (November 20, 2025).

[2] Sackett v. Environmental Protection Agency, 598 U.S. 651, 671 (2023).

[3] Clean Water Act § 301, 33 U.S.C. § 1311(a); id. § 502(7), 33 U.S.C. § 1362(7) (2018).

[4]  United States v. Riverside Bayview Homes, Inc., 474 U. S. 121, 132-133  (1985); Solid Waste Agency of Northern Cook Cty. v. Army Corps of Engineers, 531 U. S. 159, 168 (2001) (SWANCC). 

[5] 547 U.S. 715, 759 (2006) (Kennedy J., concurring in the judgment).

[6] Id. at 739 (Scalia, J. plurality opinion) (citation omitted). 

[7] Sackett, 598 U.S. at 678.

[8] Id. at 697 (Thomas, J. concurring).

[9] Id. at 728 (Kavanaugh, J. concurring in the judgment).

[10] Id. at 678 (majority opnion) (emphasis added). 

[11] Rapanos, 547 U.S. at 732 n.5 (internal citations omitted).

[12] 90 Fed. Reg. at 52518.

[13] Id.

[14] Id.

[15] Id.

[16] Id.

[17] 90 Fed. Reg. at 52520.

[18] 90 Fed. Reg. at 52519.

[19] 90 Fed. Reg. at 52521.

[20] 90 Fed. Reg. at 52522-23.

[21] 90 Fed. Reg. at 52527.

[22] Id.

[23] Sackett, 598 U.S. at 678.