EPA and Army Corps Propose Narrower Definition of “Waters of the United States”

On November 20, 2025, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers released a proposed rule to update the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). 

This definition determines the scope of federal jurisdiction for key CWA programs, including permitting for discharges and construction projects.

Why does this matter? 

The definition of WOTUS affects permitting timelines, project costs, and compliance obligations for industries such as construction, energy, and agriculture. If finalized, the new rule will likely reduce federal jurisdiction, meaning fewer waterbodies will fall under CWA regulation.

The Agencies are accepting public comments until January 5, 2026—a short window given the holidays.

Background: Importance of the WOTUS Definition

The CWA regulates “navigable waters,” defined as WOTUS. Programs that depend on this definition include:

• Section 402 (NPDES) – permits for pollutant discharges
• Section 404 – permits for dredged or fill material

However, the Act itself does not define WOTUS. Over decades, rulemakings, court decisions, and injunctions have created confusion and regional differences.
Currently, WOTUS includes five categories of waters (e.g., navigable waters, tributaries, wetlands with continuous surface connection) and excludes eight other types (e.g., waste treatment systems, prior converted cropland, certain ditches).

The new proposal aims to align with the Supreme Court’s 2023 decision in Sackett v. EPA, which narrowed federal jurisdiction over wetlands.

Key Proposed Changes

If adopted, the rule would:

1. Remove “interstate waters” from the definition of WOTUS;
2. Add definitions for the following terms:
   1. “Relatively Permanent;”
   2. “Tributary;” and
   3. “Continuous Surface Connection;” and
3. Modify exclusions of water treatment systems, prior converted cropland, and certain ditches and add an exclusion of groundwater from the definition of WOTUS.

These changes are expected to limit federal oversight, especially in arid regions and areas with seasonal water flow. Overall, the Agencies estimate that only 19% of wetlands in the National Wetlands Inventory would be jurisdictional under this approach.

New Defined Terms

The Agencies propose to add the following defined terms to further clarify the meaning of WOTUS and to align with the Sackett decision.

“Relatively Permanent”

The Agencies propose defining “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.” This term is relevant because tributaries, lakes, ponds, and wetlands must meet that definition to qualify as WOTUS and fall within the CWA’s jurisdiction. Under this proposed definition, “ephemeral waters (i.e., those with surface water flowing or standing only in direct response to precipitation (e.g., rain or snowfall)) are not jurisdictional because they are not relatively permanent.” Further, the Agencies intend the qualification of “at least during the wet season” “to include extended periods of predictable, continuous surface hydrology occurring in the same geographic feature year after year in response to the wet season . . . .” If finalized, many features would likely fall outside the Act’s jurisdiction depending on the hydrology in a certain location—particularly in more arid regions, which may only have water flow during infrequent, but significant, precipitation events. 

“Tributary”

The Agencies propose to incorporate the term ‘relatively permanent’ into the definition of a “tributary” 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.” Much of the geographic scope of WOTUS is based on tributaries of navigable waters rather than the navigable waters themselves. As a result, this definition and the definition of “relatively permanent” are critical components of the jurisdictional reach of the CWA. 

Importantly, the Agencies propose that “[f]eatures with non-relatively permanent flow . . . would sever jurisdiction upstream . . . , including flow through non-relatively permanent reaches or streams or wetlands . . . .” This change means that even if an upstream portion of a stream met the relatively permanent definition, it would not be considered a tributary if a downstream portion of the stream fails to meet the relatively permanent definition. The Agencies note that this approach may be more likely to affect features “in the arid West and mountainous regions” where “[h]ydrologic regime shifts of relatively permanent flow to non-relatively permanent flow back to relatively permanent flow may be commonly found.” 

“Continuous Surface Connection”

The Agencies propose to define “continuous surface connection” to mean “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.” Effectively, this definition creates a two-prong test to determine whether wetlands, ponds, and lakes qualify as WOTUS—i.e., (a) having surface water during the wet season and (b) abutting another WOTUS. For wetlands, the Agencies also explain that “only the portion of an abutting wetland which demonstrates surface water at least during the wet season would be jurisdictional.” The Agencies recognize that this Rule would likely result in the elimination of many wetlands from coverage under the CWA and estimate that only 19% of total National Wetland Inventory wetlands would fall within the Act’s jurisdiction.

Next Steps

The Proposed Rule likely will result in fewer waterbodies qualifying as WOTUS and therefore subject to regulation under the CWA; however, this Rule likely will also result in a clearer operating directive to regulators and regulated entities implementing the CWA. The Agencies will accept comments in support of or against the Proposed Rule through January 5, 2026.

We expect that the agencies will publish a final rule within the next six months, given the agencies’ stated intent to promptly clarify the regulations for regulated parties and given that the Supreme Court already did the heavy analytical lifting for the agencies. Additionally, we expect the final rule to be largely identical to the proposed rule for the same reason that the purpose of the rulemaking is to incorporate the Sackett decision, so there is little policy choice involved that may change in response to comments. Once the final rule is promulgated, we would be happy to assist in reviewing for implications on clients’ regulatory needs and implementing appropriate compliance protocols.