The definition of “waters of the United States” (WOTUS) establishes the geographic reach of the Clean Water Act (CWA), including the Section 404 permitting program. The Supreme Court set the parameters within which the agencies may treat aquatic features as WOTUS when it decided Sackett v. EPA. The judgment was unanimous, and the opinion of the Court was joined by five justices, with six justices joining concurring opinions. Sackett begins by recognizing that the geographic reach of WOTUS must account for the statutory term “waters,” which encompasses only “relatively permanent, standing or continuously flowing bodies of water forming geographic[al] features that are described in ordinary parlance as streams, oceans, rivers and lakes.” So, as to wetlands, Sackett “hold[s] that the CWA extends to only those wetlands that are as a practical matter indistinguishable from waters of the United States.” 

In November 2025, the US Environmental Protection Agency (EPA) and US Army Corps of Engineers (USACE) (together, the agencies) issued a WOTUS proposed rule to implement Sackett. Last month, the agencies issued a supplemental proposed rule “to supplement and seek additional comment on certain aspects” of the 2025 proposal. In this post, we examine how the 2025 Proposed Rule and 2026 Supplemental Proposed Rule line up with the findings of Sackett.  

Sackett Elements

What emerges from Sackett is a requirement that, for the three categories of waters of the United States recognized by the Court, “the party asserting jurisdiction” must establish the following elements:    

Traditional Interstate Navigable Waters

• The body of water must be a traditional navigable water within the meaning of prior Supreme Court decisions cited in the opinion of the Court.

Relatively Permanent, Standing or Continuously Flowing Bodies of Water

1. A body of water, that is
2. Relatively permanent, standing or continuously flowing, which
3. Forms a geographic feature described in ordinary parlance as a stream, ocean, river, or lake, and is
4. Connected to a traditional interstate navigable water.

Adjacent Wetlands

1. A wetland, with a
2. Continuous surface connection to a body of water in category 1 or 2 above (subject to temporary interruptions in surface connection that may sometimes occur because of phenomena like low tides or dry spells), which
3. As a practical matter is indistinguishable from the connected category 1 or 2 water, with no clear demarcation between the category 1 or 2 water and the wetland, making it difficult to determine where the water ends and the wetland begins.

Sackett Key Terms

The opinion of the Court explains key terms in its holding as follows:

Traditional Interstate Navigable Waters: “The CWA’s predecessor statute covered “interstate or navigable waters” and defined “interstate waters” as “all rivers, lakes, and other waters that flow across or form a part of State boundaries.” This Court has understood the CWA’s use of “waters” in the same way. …  the waters of the United States” principally refers to traditional navigable waters. That our CWA decisions operated under this assumption is unsurprising. Ever since Gibbons v. Ogden, 9 Wheat. 1 (1824), this Court has used “waters of the United States” to refer to similar bodies of water, almost always in relation to ships. Sackett v. EPA, 598 U.S. 651, 673 (2023) (citation omitted).

Waters: “the CWA’s use of ‘waters’ encompasses only those relatively permanent, standing or continuously flowing bodies of water forming geographic features that are described in ordinary parlance as ‘streams, oceans, rivers, and lakes.’… connected to traditional interstate navigable waters).” Id. at 678-79 (citation omitted).

Adjacent Wetlands: “‘waters’ may be read to include only those wetlands that are as a practical matter indistinguishable from ‘waters of the United States,’ such that it is difficult to determine where the ‘water’ ends and the ‘wetland’ begins. That occurs when the wetlands have a continuous surface connection to bodies that are ‘waters of the United States’ in their own right, so that there is no clear demarcation between ‘waters’ and wetlands. … We also acknowledge that temporary interruptions in surface connection may sometimes occur because of phenomena like low tides or dry spells.” Id. at 678. Natural or legal barriers between  “waters” and a wetland “break the connection such that the wetland is not “adjacent.” “…[A] barrier separating a wetland from a water of the United States would ordinarily remove that wetland from federal jurisdiction….” Id. n.16 (but an illegal manmade barrier would not remove the wetland from jurisdiction if it would otherwise be jurisdictional.)

Proposed Rules

EPA and USACE proposed a new WOTUS definition in November 2025, and in September 2026 they issued a supplemental proposed rule refining the proposed WOTUS definition, including the definitional terms “relatively permanent” and “continuous surface connection.”

The chart below compares the jurisdictional elements of the Sackett decision, the 2025 proposed rule, and the 2026 supplemental proposed rule.

Comparison of Proposed Rules to Sackett Elements of WOTUS Jurisdiction

One of the most consequential difference between the two proposed rules is their treatment of duration for relatively permanent waters and continuous surface connections. The November 2025 proposed rule would allow a water to be “relatively permanent” if it has standing or continuously flowing surface water at least during the wet season, and a wetland to meet the continuous-surface-connection standard when it has surface water and abuts a jurisdictional water during the wet season. Holding surface water during a “wet season” is not a jurisdictional element that arises from Sackett, which allows only temporary interruptions from “phenomena such as low tides or dry spells” (not regular interruptions based on seasons). By contrast, the September 2026 supplemental proposal would require water to be present every day of the year during ordinary conditions, subject to limited allowances for drought, dry spells, low tide, and certain temporary interruptions recognized in Sackett. The difference may matter most for intermittent or seasonal features and wetlands that lack perennial surface water, leaving those types of features to state and local regulation. The progression from Sackett to the 2025 proposed rule and then to the 2026 supplemental proposal reflects an increasing agency focus on the specific requirements for jurisdiction within the controlling legal boundaries established by the Supreme Court.