WOTUS Whiplash Revisited (Again): Federal Government Redefines “Waters of the United States” for the Fifth Time in Ten Years.

On November 20, 2025, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (USACE) unveiled yet another “new” definition of “waters of the United States” (WOTUS)[1] — the term that determines which streams, wetlands, ponds, and other waters fall under federal jurisdiction of the Clean Water Act. This definition (the “2025 Proposed Rule”) would replace the 2023 version issued during the Biden administration (the “2023 Conforming Rule”)[2].

In introducing the rule, the EPA and USACE explain that this revised definition meets two primary goals: 1) it more closely follows the 2023 Supreme Court decision in Sackett v. EPA[3], and 2) it provides greater regulatory certainty and program predictability to the regulated community.

Whether either of these objectives are met by the proposed rule, however, is not certain. First, depending on how some key terms are interpreted, it’s possible that the proposed rule is less faithful to the Sackett decision than the 2023 Conforming Rule. It is also unlikely that this latest definition will provide regulatory certainty, and the rule will almost certainly be challenged in court if it is finalized as proposed.

Key Changes in the 2025 Proposed Rule

Here are the major changes under the 2025 draft WOTUS rule:

1. The definition of WOTUS would still cover: traditional navigable waters and territorial seas; most impoundments of those waters; relatively permanent tributaries; lakes and ponds that are relatively permanent and have a continuous surface connection; and wetlands that are adjacent (defined as having a continuous surface connection) to such waters.
2. The proposal would remove “interstate waters” as a standalone category from the WOTUS definition. That means even if an “interstate” water has relatively permanent flow, it is not automatically subject to CWA regulation. Instead, it must qualify under a different category.
3. “Intrastate lakes and ponds” that are disconnected or not hydrologically connected to traditional navigable waters would no longer qualify automatically.
4. For the first time, the agencies explicitly exclude groundwater, including groundwater drained through subsurface drainage systems, from WOTUS.
5. The proposed rule clarifies that man-made features, such as ditches that are constructed on dry land and lack natural connection to other jurisdictional waters, generally fall outside WOTUS. The exception here is for navigable-in-fact (tidal or canal) ditches.
6. The proposed rule also includes new definitions for some key terms.
   1. “Relatively Permanent:” The proposed rule defines “relatively permanent” as “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.” The agencies explain that the use of “wet season” is faithful to the plurality’s opinion in Rapanos v. United States, 547 U.S. 715, 743 (2006) and the majority’s opinion in Sackett by excluding ephemeral streams (surface waters that flow only in direct response to precipitation) but not excluding seasonal waters. Ephemeral waters were already excluded from WOTUS under the 2023 Conforming Rule.
   2. “Continuous Surface Connection:” The proposed rule defines “continuous surface connection” as “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” This proposed definition requires both (1) abutment to a jurisdictional water; and (2) having surface water at least during the wet season.
   3. “Tributary:” Under the proposed rule, tributary is defined as “a body of water with relatively permanent flow, and a bed and banks, 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.” The rule excludes from the definition of a tributary any “body of water that contributes surface water flow to a downstream jurisdictional water through a feature such as a channelized non-jurisdictional surface water feature, subterranean river, culvert, dam, tunnel, or similar artificial feature, or through a debris pile, boulder field, wetland, or similar natural feature, if such feature does not convey relatively permanent flow.”

Notably, the 2025 Proposed Rule does not change the textual requirements for adjacent wetlands to qualify as WOTUS. Under both the 2023 Conforming Rule and the 2025 Proposed Rule, to meet the definition of WOTUS, a wetland must have a “continuous surface connection” to a jurisdictional water.

Does the 2025 Proposed Rule Faithfully Adhere to the Sackett Decision?

The 2023 Sackett Decision narrowed the scope of the Clean Water Act over certain wetlands by clarifying that adjacent wetlands must have a continuous surface connection to a WOTUS “so that there is no clear demarcation between ‘waters’ and wetlands.” 598 U.S. 651, 678 (quoting Rapanos, 547 U.S. at 742, 755 (plurality opinion)).

The 2023 Conforming Rule, issued in late summer 2023 in response to the May 2023 Sackett decision, eliminated the “significant nexus” test for demarcating an adjacent wetland and an isolated wetland and required an adjacent wetland to have a “continuous surface connection” to a WOTUS. The 2025 Proposed Rule would also require an adjacent wetland to have continuous surface connection to a WOTUS; however, the 2025 Proposed Rule now includes a definition of a “continuous surface connection,” which previously was undefined.

One could argue that the 2025 Proposed Rule with the continuous surface connection definition is actually broader than the 2023 Conforming Rule. Undefined, continuous surface connection seems relatively straightforward: there must be constant standing water connecting the wetland and the WOTUS. However, the proposed definition of continuous surface connection explicitly considers that the “continuous surface connection” can be dry for an extended period, just not during the wet season.

From a practical standpoint, there is little doubt that the Trump administration will interpret either regulation more restrictively than the Biden administration did or would. Further, one could argue that such an interpretation is consistent with the majority’s analysis in the Sackett decision.[4] From a textual interpretation, however, it’s questionable if the new definition of continuous surface connection in the 2025 Proposed Rule achieves the administration’s stated goal of faithfully abiding by the Sackett decision. Therefore, if challenged in court, especially given the overturning of Chevron deference in the Loper Bright decision, it seems uncertain whether the 2025 Proposed Rule would more faithfully adhere to the Sackett decision than the 2023 Conforming Rule would.

Is the 2025 Proposed Rule “Clear and Durable”?

Despite the agencies’ framing of the proposal as delivering clarity and eliminating uncertainty, the 2025 Proposed Rule introduces new ambiguities. The concept of a “wet season” is central to defining both “relatively permanent” waters and “continuous surface connection,” but the rule does not provide a clear definition or standard for determining the wet season.

The term “wet season” is not defined in the rule and the agencies do not provide a clear standard for establishing the wet season. The agencies acknowledge that wet season will depend on a number of different factors, including geography, climate, precipitation topography, soils, and other conditions.[5] For that reason, a clear method will be needed to allow the regulated community to interpret and apply wet season at a site-specific level.

In an attempt to provide a clear method, the agencies propose to use a precipitation tool, “the metrics from the Web-based Water-Budget Interactive Modeling Program (WebWIMP) which are reported in APT,” to determine the wet season. However, the agencies acknowledge that even this tool is not universal: “the agencies recognize that the WebWIMP outputs reported in APT may not have complete functionality in certain territories[.]” Adding further uncertainty to the application of the outputs, the link to the WebWIMP model gives a “failed to connect” error, so one cannot even look at how the different outputs might yield a wet season for different areas to evaluate the potential effectiveness of the proposed approach.

One area where the rule does create regulatory certainty is by excluding all ditches constructed in entirely dry land from the WOTUS definition. Previously, certain upland ditches could still be considered jurisdictional if the ditch had a relatively permanent flow. Under the 2025 Proposed Rule, even with a relatively permanent flow, those ditches would no longer be considered a WOTUS. Moreover, a wetland adjacent to an upland ditch would not be considered a WOTUS, even if there was a continuous surface connection to the ditch

As a result, the 2025 Proposed Rule does not appear to solve all the issues related to regulatory certainty of relatively permanent waters or adjacent wetlands, but the rule does provide some certainty in relation to upland ditches.

Why This Matters — for Landowners, Developers, States, and Wetlands

The practical implications of these changes could be far-reaching:

1. For owners of land that contains seasonal waterbodies, or wetlands that only flood part of the year, the proposed rule might remove their lands from federal jurisdiction, which could result in fewer federal permitting requirements under the CWA. However, these landowners are unlikely to have the regulatory certainty that is promised.
2. For developers, farmers, and builders, the implementation of this rule could translate into fewer regulatory burdens and permit delays. From a practical standpoint, however, it’s unclear that this rule is necessary for such relief—the implementation of the 2023 Conforming Rule could arguably achieve the same results. Moreover, the 2025 Proposed Rule is likely to be challenged and could result in a continued patchwork of implementation that depends on court jurisdictions. This is similar to the existing conditions, where half the country is currently operating under the pre-2015 regulatory framework and half under the 2023 Conforming Rule.
3. For states and tribes, the new rule reinforces their role: the EPA and USACE emphasize that states and tribes remain primary stewards of local land and water regulation where federal protections no longer apply. For example, in Ohio any reduction in federal wetland protection is backstopped by the state’s wetland protections.
4. On the other hand, environmental and conservation concerns are significant. Regulatory-impact analysis indicates that only about 19% of wetlands on the National Wetlands Inventory may retain WOTUS status under the new rule. Environmental groups have raised concerns about water quality, flood control, habitat loss, and ecological resilience, particularly in regions where wetlands, seasonal streams, and prairie potholes play a large role in groundwater recharge, carbon sequestration, and biodiversity.

What’s Next — Public Input, Politics, and What to Watch

1. The proposed rule was published in the Federal Register on November 20, 2025.
2. The public comment period is open now through January 5, 2026
3. After the comment period, the EPA and USACE will review submissions, revise the rule, as needed, and may finalize it.
4. Landowners, developers, environmental groups, and states are likely to weigh in heavily. Given continuing legal and political divisions over federal water jurisdiction, additional litigation or regulatory pushback seems probable. It is reasonable to expect that any final rule will be immediately challenged in court.

If you have questions about state or federal permitting under the Clean Water Act or Ohio laws, please contact Nat Morse, Kristin Watt, Ryan Elliott, or your Vorys attorney.

[1] 90 FR 52498 (Nov. 20, 2025)

[2] ….which replaced the 2023 Biden-era revised definition of WOTUS, which replaced the Trump-era 2020 Navigable Waters Protection Rule, which replaced the prior Trump-era Step One Rule from 2019 (which functionally reinstated pre-2015 regulations), which replaced the Obama-era 2015 Clean Water Rule, which incorporated Justice’s Kennedy’s concurring opinion from the Rapanos decision, which modified the current understanding of WOTUS following the SWANCC decision that eliminated isolated wetlands from WOTUS.

[3] The 2023 Supreme Court decision in Sackett v. EPA narrowed the scope of federal water protections, holding that CWA jurisdiction applies only to “relatively permanent, standing or continuously flowing bodies of water” (streams, lakes, rivers, oceans) and wetlands that have a “continuous surface connection” to those waters. Sackett v. Environmental Protection Agency, 598 U.S. 651 (2023).

[4] See, e.g., Sackett, 598 U.S. at 678 (“We also acknowledge that temporary interruptions in surface connection may sometimes occur because of phenomena like low tides or dry spells.”)

[5] 90 FR at 52524 (the agencies explain that “[t]he time period, including duration, constituting a ‘wet season’ varies across the country due to many relevant factors including climate, hydrology, topography, soils, and other conditions;” the proposed rule also notes that 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 in response to the wet season, such as when average monthly precipitation exceeds average monthly evapotranspiration. As proposed, surface hydrology would be required to be continuous throughout the entirety of the wet season.”)