Somach Simmons & Dunn | Attorneys at Law
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On November 20, 2025, the U.S. Army Corps of Engineers (USACE) and Environmental Protection Agency (EPA) published a proposed rule to redefine “waters of the United States,” commonly referred to as WOTUS, to better align with the U.S. Supreme Court’s ruling in Sackett v. EPA, 598 U.S. 651 (2023) (Sackett). This rule, if adopted, would overall narrow the definition of WOTUS, reducing the reach of the Clean Water Act (CWA) and reducing protections for wetlands and waterways across the country. The rule has potentially significant consequences for project cost and schedules by removing a common federal nexus to more efficient federal Endangered Species Act (ESA) permitting. The rule also has implications for water management as it would expand jurisdiction to tributaries used for water transfers, seemingly eliminating an existing exclusion from National Pollutant Discharge Elimination System (NPDES) permit requirements.
The CWA was passed in 1972 to establish federal jurisdiction over what was perceived as the nation’s waters, to restore and protect these waters for future generations. The CWA authorized USACE and EPA to promulgate regulations defining WOTUS, which they eventually did as traditional navigable waters, interstate waters, all other waters affecting interstate or foreign commerce, impoundments of waters within the U.S., tributaries, the territorial sea, and adjacent wetlands. Thereafter, in Rapanos v. United States, 547 U.S. 715 (2006) (Rapanos), the Supreme Court adjudicated a challenge to the classification of wetlands but failed to reach a majority opinion. A plurality was reached instead and the “significant nexus” standard articulated in Justice Anthony Kennedy’s concurrence became the reigning definition for wetlands for almost a decade. This definition, however, proved difficult to implement, so in 2015 the Obama Administration redefined WOTUS in its Clean Water Rule that, amongst other things, defined tributaries as those that directly or indirectly flow to traditional navigable water, interstate water, or territorial seas, and wetlands as those bordering, contiguous, or neighboring, including waters physically separated from, other jurisdictional waters.
The Clean Water Rule was repealed by the Trump Administration in 2019 and replaced with the Navigable Waters Protection Rule in 2020, which redefined tributaries to exempt ephemeral streams and redefined wetlands as only those waters that directly abut other jurisdictional waters or are separated by natural barriers, like berms, or permeable artificial barriers, like certain levees. The 2020 rule was stayed pending litigation until it was vacated (discussed here by SSD) and replaced with the Biden Administration’s first 2023 rule (discussed here by SSD) that returned to the standards defined in the Rapanos opinion, with some alterations. Biden’s rule, however, was amended later that year when the Supreme Court issued its ruling for Sackett (discussed by SSD here and here) that held USACE and EPA may only regulate wetlands “with a continuous surface connection” to another jurisdictional water such that they are “indistinguishable” from those waters. The revised so-called Conforming Rule was challenged in several federal courts for not complying with Sackett but is still active in nearly half the country whereas the other half adheres to pre-Obama rules and Sackett.
Wetlands: To better comply with Sackett, per the Trump Administration, the proposed rule would require the application of a two-part test to determine a wetland’s jurisdictional status: (i) the wetland must touch a jurisdictional water; and (ii) it must contain surface water at some time during the year. Same as previous definitions, wetlands, as well as relatively permanent lakes and ponds, must have a continuous surface connection to a WOTUS. The proposed rule also would redefine “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” and eliminate ephemeral waters as WOTUS because they do not comply with this new definition. The proposed rule does not, however, define the term “wet season.”
Tributaries: The proposed rule would define “tributary” 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.” The rule would exclude from the definition of “body of water” those waters that “contribute[] surface water flow to a downstream jurisdictional water through a feature such as a channelized non-jurisdictional surface water feature, subterranean river, culvert, dam, tunnel, or similar artificial feature, or through a debris pile, boulder field, wetland, or similar natural feature, if such feature does not convey relatively permanent flow.”
Tributaries Used for Water Transfers: Under the proposed rule, however, a tributary used for a “water transfer . . . (as the term is applied under 40 CFR 122.3) currently in operation” would be a WOTUS. Pursuant to the NPDES Water Transfers Rule adopted in 2008, title 40, section 122.3 of the Code of Federal Regulations currently exempts discharges from water transfers (i.e., the transfer of water from one WOTUS to another, via tunnels, channels, and/or natural stream features, without intervening industrial, municipal or commercial use) from NPDES permit requirements, although the exclusion does not apply to any pollutants introduced by the water transfer activity or the water being transferred. In proposing the NPDES Water Transfers Rule, EPA was concerned that subjecting water transfers to a federal permitting scheme could unnecessarily interfere with state decisions on allocations of water rights. The preamble to the proposed rule acknowledges “the importance of water management practices in the States and the explicit policy directives of Congress to recognize the authority of States to allocate and manage water resources within their respective jurisdictions,” but nevertheless proposes this jurisdictional expansion “to ensure vital water management practices continue as currently implemented regarding water transfers.” Citing Justice Antonin Scalia’s plurality opinion in Rapanos, 547 U.S. at 743‑44, the preamble to the proposed rule further explains that “[e]ven if a waterbody does not satisfy the definition of ‘tributary,’ it may function as a point source (i.e., ‘discernible, confined, and discrete conveyance,’ 33 U.S.C. 1362(14)), such that discharges of pollutants from these features could require a [CWA] permit.”
Ditches: The proposed rule would exclude all ditches “that are constructed or excavated entirely in dry land,” eliminating an entire category of ditches that had historically been treated differently in different contexts. Ditches constructed in wetlands or tributaries will still be jurisdictional, and in some rare cases, a ditch constructed in dry land may meet criteria for federal jurisdiction, such as a navigable canal.
Interstate/Intrastate Waters: The proposed rule also would remove the term “interstate waters” from any WOTUS definition along with the qualifier “intrastate” from the previously termed “intrastate lakes and ponds” with the reasoning that these waters may encompass bodies of water that are not relatively permanent, standing, or continuously flowing or that are not connected to a downstream traditional navigable water or the territorial seas.
Groundwater: Under the proposed rule, groundwater would be expressly excluded from WOTUS, although not groundwater that contributes to baseflow in relatively permanent streams.
Prior Converted Cropland: The proposed rule would specify that the existing prior converted cropland exclusion does not apply to abandoned cropland or cropland not used for agricultural purposes at least once in the five years preceding its determination under the CWA. Where abandoned cropland is converted to wetlands, it still must satisfy the two-part test to be considered jurisdictional.
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This rule, if implemented, would result in an overall considerable reduction in WOTUS, putting at risk numerous wetlands and waterways that have been protected under the CWA for decades. Paradoxically, the rule would expand jurisdictional waters to currently non-WOTUS tributaries that are part of operational water transfers in an apparent contravention of Sackett, where the Supreme Court held that CWA’s use of “waters” should only encompass “ ‘those 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” ’ .” 598 U.S. at 671, quoting Rapanos, 547 U.S. at 739. While the proposed rule is presumptively prospective—meaning projects already approved would not be impacted—it should be on the radar of anyone planning a project or in the environmental review process for actions subject to the CWA.
Narrowing the definition for WOTUS would have the effect of facilitating development and other land operations like agricultural uses that have been beholden for many decades to wetlands avoidance and other costly mitigation measures. However, the narrower definition could result in the significant consequence of eliminating the most common federal nexus for permitting under the federal ESA. For the many projects currently requiring a CWA Section 404 permit, the federal permitting agency can request consultation with the U.S. Fish and Wildlife Service and National Marine Fisheries Service under Section 7 of the ESA to more efficiently obtain species incidental take authorization for the proposed action. If no CWA permit is required, as would increasingly occur under the proposed rule, project proponents would have to apply for individual take permits under Section 10 of the ESA, including preparing a habitat conservation plan—a much longer and more onerous process that will increase the time and cost to implement development projects that formerly could rely on the Section 404 permit process to satisfy the ESA. Likewise, the removal of the NPDES permit exemption for operational water transfers may burden water management.
If adopted, the proposed rule may be stayed by federal courts in the myriads of lawsuits sure to be filed by environmental watch dog groups around the country, same as the 2020 rule. States like California that have their own suite of water protection laws and definitions (e.g., Porter-Cologne Water Quality Control Act, State Water Resources Control Board adopted Wetland Definition, California Environmental Quality Act) would be impacted far less by this new rule than states that have relied exclusively on federal protections.
The deadline for public comment on the proposed rule is January 5. Specifically, “[t]he agencies seek comment on [] implementation of the proposed definition of ‘tributary,’ including on sources of information that can be relied on to determine if a tributary is part of a water transfer.”
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