Trump Administration Proposes New Rule Defining “Waters of the United States”

The proposed rule would scale back federal jurisdiction under the Clean Water Act.

By Nikki Buffa, John C. Heintz, Michael G. Romey, Jennifer K. Roy, Lucas I. Quass, and Samantha Yeager

On November 17, 2025, the United States Environmental Protection Agency (EPA) and the Department of the Army, Corps of Engineers (USACE) (together with EPA, the Agencies) announced a proposed rule that would revise the definition of “waters of the United States” (WOTUS) under the federal Clean Water Act (CWA).¹ The definition of WOTUS determines the scope of waters and wetlands subject to federal regulation under the CWA.

In its 2023 Sackett decision, the Supreme Court narrowed the scope of federally jurisdictional waters to “relatively permanent, standing, or continuously flowing bodies of water” and wetlands with a “continuous surface connection” to such waters.² The Biden administration responded in 2023 by revising regulations defining WOTUS in an attempt to align with the Court’s decision. In 2025, under the Trump administration, the Agencies held nine listening sessions to solicit feedback on key aspects of the definition of WOTUS. In response, this newly issued proposed rule further clarifies the post-Sackett regulatory landscape and could reduce the number and size of federally jurisdictional waters.

We provide the history underlying this rulemaking and our insights on the proposed rule and its implications below.

Background

Since the 1970s, the Agencies have defined WOTUS by regulation. A string of US Supreme Court decisions has addressed the definition, the most recent of which was Sackett v. Environmental Protection Agency. In Sackett, the Court held that the CWA only regulates wetlands with a “continuous surface connection” to other “traditional” waters of the United States.³ The opinion largely relies on Justice Scalia’s four-Justice plurality opinion in Rapanos v. United States (2006), which established a narrow definition that came to be known as the “continuous surface connection” test.⁴ In a lone concurring opinion in Rapanos, Justice Kennedy provided a much broader interpretation that 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.”⁵ Justice Kennedy’s approach is commonly referred to as the “significant nexus” test.

Since no majority opinion emerged, Rapanos resulted in varied application across the country. Subsequent administrations attempted to clarify the definition of WOTUS through regulatory changes, including the Obama administration’s Clean Water Rule, the Trump administration’s 2020 Navigable Water Protection Rule, and the Biden administration’s Revised Definition of “Waters of the United States.” In Sackett, however, the Court expressly rejected the “significant nexus” test, which had formed the basis of the Obama and Biden administration rules.

In September 2023, the Biden administration amended its original January 2023 WOTUS rulemaking to conform with Sackett, including by eliminating the “significant nexus” standard; redefining “adjacent” to mean having a continuous surface connection, and revising provisions to pare back jurisdictional waters to those that are “relatively permanent, standing or continuously flowing” or those with a continuous surface connection to such waters.⁶ In issuing the amended 2023 rule, the Agencies did not engage in a formal notice and comment period and did not explicitly define some of the jurisdictional terms utilized by the Supreme Court.

According to the Agencies’ current proposed rule, some stakeholders have expressed concerns that the amended 2023 rule does not adequately comply with Sackett and is difficult to implement. Accordingly, the proposed rule states that it revises the amended 2023 rule to “provide greater regulatory certainty, and increase Clean Water Act program predictability and consistency by clarifying the definition of ‘waters of the United States.’”⁷ This proposed rule follows a March 2025 memorandum from the Agencies on how to interpret “continuous surface connection” and a subsequent Federal Register notice soliciting feedback from stakeholders and co-regulators on key aspects of the WOTUS definition.

The Proposed Rule and Its Implications

The proposed rule defines WOTUS to include: (1) traditional navigable waters and the territorial seas; (2) most impoundments of WOTUS; (3) relatively permanent tributaries of traditional navigable waters, the territorial seas, and impoundments; (4) wetlands adjacent to traditional navigable waters; and (5) lakes and ponds that are relatively permanent and have a continuous surface connection to a traditional navigable water.⁸ If finalized, the rule would remove interstate waters as a stand-alone category under WOTUS.⁹ Such interstate waters would only be deemed WOTUS if they fall under the remaining five categories.

Further, the proposed rule endeavors to provide greater clarity for those implementing the CWA, including by adding definitions for “relatively permanent” and “continuous surface connection,” two terms adopted by the Supreme Court in the Sackett decision but not defined in the amended 2023 rule. Under the proposed rule, “relatively permanent” means “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.”¹⁰ The proposed rule points to agency guidance and modeling programs on “wet seasons” and suggests that this term provides a bright-line test for those implementing the CWA. The Agencies are soliciting comments on additional implementation methods and tools.¹¹

The Agencies’ proposed definition of “continuous surface connection” creates a “two-prong test that requires both (1) abutment of a jurisdictional water and (2) having surface water at least during the wet season.”¹² According to the proposed rule, “abutting” specifically means “touching.”¹³ While the proposed rule would not change the regulatory definition of “wetland,” the “abutment” requirement could reduce the number and size of wetlands under federal jurisdiction.

Additionally, the proposed rule would update the exclusions for waste treatment systems, converted croplands, and ditches, and would expressly exclude groundwater from WOTUS.

The proposed rule carries several implications. These changes have the potential to provide greater regulatory certainty and clarity to project proponents and could streamline jurisdictional determinations, which are used to identify whether a wetland or waterbody is federally covered under the CWA. However, as the proposed rule repeatedly points out, states, Tribes, and local governments retain authority under the CWA to enact more stringent regulatory requirements. As such, project proponents should be aware of existing laws and regulations in such jurisdictions and should monitor for proposed changes that states, Tribes, and local governments may utilize to fill in the gaps from reduced federal oversight.

Next Steps

Interested stakeholders have until January 5, 2026, to submit public comments on the proposed rule, including online at www.regulations.gov to Docket ID No. EPA-HQ-OW-2025-0322. The Agencies will also be holding two public meetings, to be announced. Notably, this proposed rule is just the start of what could become a long rulemaking process. Any final rule may be subject to litigation, which could further extend the timeline before it might take effect.

Latham & Watkins will continue to monitor developments in this area.

1. 90 Fed. Reg. 52498 (Nov. 20, 2025) (Proposed Rule). ↩︎
2. Sackett v. Environmental Protection Agency, 598 U.S. 651, 678-79 (2023). ↩︎
3. Id. ↩︎
4. Rapanos v. United States, 547 U.S. 715, 742 (2006). ↩︎
5. Id. at 759. ↩︎
6. 88 Fed. Reg. 61964 (Sep. 8, 2023). ↩︎
7. Proposed Rule at 52499. ↩︎
8. Proposed Rule at 52514. ↩︎
9. Id. at 52516. ↩︎
10. Id. at 52517. ↩︎
11. Id. at 52519, 52523. ↩︎
12. Id. at 52527. ↩︎
13. Id. ↩︎