On November 17, 2025, the Environmental Protection Agency (“EPA”) together with the United States Army Corps of Engineers (“the Corps”) announced a proposed rule to redefine the term “waters of the United States” under the Clean Water Act (“CWA”). The intent of the proposal is to bring the definition of waters of the United States, commonly referred to as WOTUS, in line with the United States Supreme Court 2023 decision Sackett v. EPA, 566 US 120 (2023). This proposal marks the sixth time since 2015 that the regulatory definition of WOTUS has changed and is likely to prompt litigation after it is formally finalized. The proposal has been published the Federal Register and is currently open for public comment through January 5, 2026.

Background CWA, Current WOTUS Rule, and Sackett

The CWA of 1972 is the leading federal water pollution statute in the United States. The purpose of the Act is to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a). To achieve this goal, the CWA has established permitting programs to limit the amount of pollution discharged into waters and wetlands. Under the National Pollution Elimination System (“NPDES”) program, it is illegal for anyone to discharge a pollutant from a discernable, concrete source into “navigable waters” without first receiving a permit from EPA. 33 U.S.C. § 1342. Similarly, the 404 permitting program prohibits the discharge of “dredged or fill material” into “navigable waters” without a permit from the Corps. 33 U.S.C. § 1344. Crucially, both the NPDES and 404 permitting programs cover activities that occur within “navigable waters.” Although the term “navigable waters” is a legal term of art which is generally understood to refer to waters which can be used to facilitate interstate or foreign commerce, the CWA defines the term as “waters of the United States, including the territorial seas.” 33 U.S.C. § 1362(7). However, the CWA does not define the term “waters of the United States.” Instead, it has been left up to EPA and the Corps to define the term.

In the decades since the CWA was passed, crafting a lasting definition of WOTUS has been a struggle for the agencies and courts, and the formal regulatory definition has changed several times. A full timeline of the different definitions of WOTUS is available here. Most recently, the definition of WOTUS was revised in 2023, first through a finalized rulemaking conducted by EPA during the Biden administration, and then again following the Supreme Court’s ruling in Sackett v. EPA. Under the initial 2023 final rule, the definition of WOTUS included five categories of waters: (1) traditional navigable waters that could be used in interstate for foreign commerce, the territorial seas, and interstate waters including interstate wetlands; (2) impoundments of waters otherwise identified as WOTUS; (3) tributaries of traditionally navigable waters or impoundments that met either the relatively permanent standard or significant nexus test articulated by the Supreme Court in Rapanos v. US, 547 US 715 (2006); (4) wetlands adjacent to any WOTUS with “adjacent” understood to mean neighboring, bordering, or contiguous; and (5) all other lakes, ponds, streams, and wetlands that satisfied either the relatively permanent standard or significant nexus test. Further information on the initial 2023 WOTUS definition can be found here.

The initial 2023 WOTUS rule fully incorporated both the relatively permanent standard and the significant nexus test which stem from the Supreme Court’s decision in Rapanos v. US. In that case, the Supreme Court was asked to consider the degree to which wetlands could be included in the definition of WOTUS. The Court was unable to reach a majority opinion, instead issuing a plurality opinion and a concurring opinion. The plurality opinion articulated the relatively permanent standard which would extend the definition of WOTUS to those waters which are “relatively permanent, standing or continuously flowing” and then to those wetlands which share a “continuous surface connection” with such waters. The concurring opinion, on the other hand, crafted the significant nexus test which extended the WOTUS jurisdiction to those wetlands that share a “significant nexus,” with a water that is already recognized as a WOTUS. A significant nexus would exist if a wetland “significantly affect[s] the chemical, physical, and biological integrity” with a recognized WOTUS.

Weeks after the first 2023 definition of WOTUS was finalized, the Supreme Court released its decision in Sackett v. EPA. Like in Rapanos v. US, the Court in Sackett v. EPA was asked to consider to what extent wetlands should be included in the WOTUS definition. Specifically, the plaintiffs specifically asked the Supreme Court to formally overturn the significant nexus test and adopt the relatively permanent standard. Ultimately, the Court did just that, concluding that the term “waters” in “waters of the United States” refers to “only those relatively permanent, standing or continuously flowing bodies of water […] described in ordinary parlance as streams, oceans, river, and lakes” and to wetlands that are “indistinguishable” from such waters due to a continuous surface connection.

Following the Supreme Court’s decision in Sackett v. EPA, EPA issued what is known as the Conforming Rule to revise the WOTUS definition in light of the Court’s ruling. Issued in August 2025, the Conforming Rule cut references to the significant nexus test from the WOTUS definition and clarified that the word “adjacent” with respect to adjacent wetlands meant “having a continuous surface connection.” The rule also noted that only those tributaries of navigable waters which satisfy the relatively permanent standard would be considered WOTUS. To learn more about the Conforming Rule, click here.

When the Trump administration took office in 2025, it announced an intention to revisit numerous environmental regulations, including the definition of WOTUS. After holding a series of listening sessions with stakeholders across the county, EPA and the Corps have released their latest proposal to redefine the term.

Proposed WOTUS Definition

According to EPA, its latest WOTUS proposal has two primary goals: to bring the definition in line with Sackett v. EPA and to provide more clarity to landowners and the public as to which waters fall under the CWA’s permitting jurisdiction. To that end, it is proposing to include five categories of waters in the definition of WOTUS and is introducing new definitions intended to clarify when a water is relatively permanent and what constitutes a continuous surface connection.

Under the proposal, the following categories of waters would be considered WOTUS:

• Traditionally navigable waters which may be used to facilitate interstate or foreign commerce, including all waters which are subject to the ebb and flow of the tide and the territorial seas.
• Impoundments of waters otherwise identified as WOTUS.
• Tributaries of traditionally navigable waters which are relatively permanent, standing or continuously flowing.
• Wetlands adjacent to a traditionally navigable water or tributary.
• Lakes and ponds that do not fall into the above categories but which are relatively permanent, standing or continuously flowing and share a continuous surface connection with a traditionally navigable water or tributary.

Importantly, the proposal would not include interstate waters as a category of WOTUS. This is a departure from previous WOTUS definitions, almost all of which have included interstate waters as WOTUS. These categories also differ from previous WOTUS definitions by specifying that waters which fall under category five must not only be relatively permanent but must also share a continuous surface connection with a traditionally navigable water or tributary to be considered WOTUS. Under past definitions, the continuous surface connection standard was applied only to wetlands.

Along with making changes to the categories of waters considered WOTUS, the proposed rule also includes new definitions for the terms “relatively permanent,” “continuous surface connection,” and “tributary.” Under the proposed rule, “relatively permanent” would be defined as “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.” EPA notes that “the wet season” would refer to a predictable and extended period of time when surface water is present in a geographical feature in response to an annual wet season when precipitation is greater than average. However, that would not include what are known as “ephemeral waters” which are geographic features that contain surface water only in direct response to precipitation. Under this definition of relatively permanent, a river which periodically dries out in the late summer months, but which flows during the winter and spring after increased rain and snowmelt could be considered a WOTUS, while a creek that is dry most of the time and flows only after a heavy rain would likely not be considered a WOTUS.

The proposed rule would define “continuous surface connection” as “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” EPA clarifies that this definition presents a two-pronged test which requires a wetland or waterbody to both: (1) abut, as in directly touch, a traditionally navigable water or tributary; and (2) have surface water at least during the wet season. Wetlands or waters with a sub-surface connection to a recognized WOTUS – meaning connected to a WOTUS by water that is not on the surface but is not deep enough underground to be considered groundwater – would not be considered a WOTUS under this definition. Additionally, EPA notes that CWA permitting jurisdiction would only be extended to the portion of a wetland which retains surface water at least during the wet season.

Finally, the proposal would define “tributary” as “a body of water with relatively permanent flow, 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.” Under this definition, a tributary to a traditionally navigable water that has a discernable bank and bed, and which has surface water at least during the wet season could be considered a WOTUS. However, a water without a bank and bed, such as a grassed waterway, would likely not be considered a WOTUS even if it held surface water year-round.

Besides defining what a WOTUS is, the proposal also strengthens language describing what a WOTUS is not. Particularly relevant to agriculture, the proposal would strengthen existing exclusions for prior converted cropland. The term “prior converted cropland” comes from the Wetland Conservation provisions of the 1985 Farm Bill, better known as Swampbuster. Prior converted cropland refers to wetland areas which were converted to agricultural land capable of producing a crop prior to December 23, 1985. Although prior converted cropland is currently excluded from the definition of WOTUS, the proposed rule would clarify that such land would only lose that exclusion and become subject to CWA jurisdiction if it were abandoned and reverted to a wetland that met the definition of “adjacent wetland” under WOTUS.

Next Steps

The proposed rule was published in the Federal Register on November 20, 2025, formally initiating a period of public comment that is currently set to end on January 5, 2026. While public comments may address any part of the proposal, EPA is specifically requesting comment on the following: whether WOTUS should be limited to only traditionally navigable waters and those wetlands that share a continuous surface connection with such waters; whether “relatively permanent” should include only those waters that contain surface water year-round instead of waters that contain surface water at least during an annual wet season; and whether a wetland must have a continuous surface connection with a navigable water or tributary year-round to be considered a WOTUS.

After the period of public comment concludes, EPA and the Corps will review the comments it receives before drafting and issuing a final rule. Once the rule becomes finalized, it is very likely that it will be challenged in court. Since 2015, all final regulations defining WOTUS have led to lengthy legal battles that often result in separate WOTUS definitions being applied across the country as the court cases proceed. Importantly, the last time a court was asked to consider whether the regulatory definition of WOTUS complied with the text of the CWA, the doctrine of Chevron deference was still the law of the land. Under Chevron deference, courts were instructed to defer to agency interpretations of ambiguous statutory language so long as the interpretation was reasonable. However, in 2024, the Supreme Court overturned Chevron deference in its landmark decision Loper Bright Enters. v. Raimondo, 603 US 369 (2024). According to the Supreme Court, judges should not defer to agency statutory interpretations but should themselves state what the law is. This means that judges asked to consider whether a future WOTUS definition complies with the CWA may rely on judicial interpretations of the statute rather than agency interpretations.

The new proposed WOTUS definition has kicked off another cycle of attempting to define a crucial, but ambiguous term that determines when someone needs a CWA permit and when they do not. Whether the final definition will satisfy EPA’s goals of crafting a durable definition remains to be seen.

To view the proposed WOTUS rule and learn how to submit a comment, click here.

To view the current definition of WOTUS, click here.

To view the text of Sackett v. EPA, click here.

To view the text of the CWA, click here.

For more CWA resources from the National Agricultural Law Center, click here.