On November 20, 2025, the Environmental Protection Agency (EPA) and the Army Corps of Engineers proposed a rule to revise the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). The revisions follow the Supreme Court’s 2023 decision in Sackett v. EPA, which significantly narrowed the CWA’s coverage over wetlands and impermanent (i.e., seasonal) bodies of water by requiring that WOTUS be “relatively permanent” and maintain a “continuous surface connection” with a jurisdictional water.
Virtual public comment sessions on December 16 highlighted where the proposed rule may create clarity and where ambiguities remain.
The official public comment period runs through January 5, 2026. Regulated entities should continue to assess how the proposal impacts or raises questions about their obligations under the CWA and consider submitting comments before the deadline.
Defining Waters of the United States
The CWA establishes federal jurisdiction over the discharge of pollutants to “navigable waters,” which is defined as “the waters of the United States, including the territorial seas.” However, the CWA does not define WOTUS. The lack of statutory clarity has meant decades of litigation over what waters and wetlands are subject to federal regulation; ambiguity among regulated entities over the application of the definition to permitting and permissible development; and conflicting guidance, clarification, and rulemaking from various administrations.
In 2006, Rapanos v. United States produced two competing definitions of WOTUS. A four-Justice plurality opinion by Justice Antonin Scalia set forth a narrow definition that included relatively permanent, standing, or continuously flowing bodies of water and wetlands with a continuous surface connection to traditional interstate navigable waters. Justice Anthony Kennedy, in a concurring opinion, set forth a broader interpretation, which included waters and wetlands that “possess a ‘significant nexus’ to waters that are or were navigable in fact or that could reasonably be so made.”
In 2015, under the Obama Administration, the agencies sought to broadly redefine WOTUS through the Clean Water Rule, relying on the significant nexus test. In 2017, President Trump reversed course through Executive Order 13778, directing the agencies to consider repealing the Clean Water Rule and replacing it with a regulation adopting the continuous surface water connection test.
In 2020, the agencies promulgated the 2020 Navigable Water Protection Rule to redefine WOTUS, relying in part on the continuous surface water connection test. The Navigable Water Protection Rule was subject to numerous lawsuits and ultimately vacated by a federal court. President Biden repealed Executive Order 13778 through Executive Order 13990. In January 2023, the agencies published a rule expanding federal jurisdiction to waters and wetlands that met either the relatively permanent or significant nexus standard.
In May 2023, the Supreme Court in Sackett v. EPA adopted Justice Scalia’s narrow interpretation of WOTUS from Rapanos. The agencies subsequently published a new rule that:
- Removed the significant nexus standard that informed the January 2023 rule.
- Required that wetlands protected under the CWA have a continuous surface connection to navigable waterways.
- Removed interstate wetlands as WOTUS.
New Proposed Changes
The agencies now propose to further redefine WOTUS to conform with Sackett. The agencies’ stated aim is to provide clarity and to reduce red tape by defining previously undefined terms, clarifying several exclusions to what is considered WOTUS, and delegating additional authority to the states to manage their local land and water resources.
Among other changes, the proposed rule removes interstate waters from the definition of WOTUS; previously classified interstate waters must meet other jurisdictional criteria to remain “waters of the United States.” “Continuous surface connection” is newly defined to mean “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” “Relatively permanent waters” is newly defined to mean “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.”
The concept of “wet season” as used in these newly defined terms is left without an explicit definition in the proposed rule. The drafters explain that the term 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.” The agencies appreciate that the wet season will vary by region and depend on hydrologic conditions that support continuous surface water flow. The EPA seeks comments on (1) the consistency of its interpretation of “wet season” with Rapanos; (2) what thresholds to consider in defining a wet season; and (3) potential challenges with implementing the agencies’ proposed approach.
The proposed rule further includes an explicit exclusion for groundwater and defines and excludes certain ditches from WOTUS, clarifies what constitutes excluded prior converted cropland, maintains the waste treatment exclusion with an additional definition, and reaffirms that wetlands must be indistinguishable from jurisdictional waters through a continuous surface water connection.
“Tributary” is defined 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.” This clarification for “tributary” would explicitly exclude certain features such as wetlands if they did not have relatively permanent flow.
Virtual Public Comment
The agencies held two virtual public comment sessions on December 16, 2025, where stakeholders and members of the public spoke for and against the changes.
Those for the changes supported the clarity provided to the agricultural and development sectors and the preservation of state authority over water use. Others supporting the changes spoke of reduced costs associated with reduced bureaucratic red tape for landowners.
Those against the changes spoke of potential negative downstream effects from the proposed rule, including decreased protection of wetlands, increased movement of pollutants and pathogens into the water supply, damage to ecosystems, and increased flooding. Others also stated that it would significantly increase the burden on state and local governments that would need to implement new systems to ensure clean drinking water, as well as on businesses that would need to reassess compliance under the new definitions.
Stakeholders and members of the public also expressed concern that the term “wet season” would raise new compliance questions because the proposed rulemaking does not provide clear guidance on how to determine the wet season for jurisdictional purposes in a given region.
The 45-day comment period is open for written comment through January 5, 2026.
Implications for Industry
The proposed changes could provide some much-needed clarity and ease burdens on industry brought on by heavy CWA restrictions. Clearly defined exclusions could help alleviate regulatory concerns in certain sectors, and restricting the definition of WOTUS could reduce costs for businesses holding land with water features that would no longer be federally regulated under the proposed rule.
At the same time, the revisions may create additional ambiguities. The lack of clarity around wet seasons could create an additional administrative burden for those assessing compliance. It could also further encourage an inconsistent patchwork of regulation around the country because state governments have authority under the CWA to enact more stringent regulatory requirements.
Businesses should consider submitting public comments to help shape the final rule. Stakeholders may find it beneficial to address potential ambiguities in the proposal, such as the definition of “wet season.”
Our team is ready to assist you with understanding the current application of WOTUS, as well as how to address proposed changes.
If you have any questions, or would like additional information, please contact one of the attorneys on our Environment, Land Use & Natural Resources team.
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