Proposal to Update Definition of “Waters of the United States”

The new supplemental proposed rule (updated from the initial November 2025 proposed rule) would strip the few remaining federal protections of U.S. wetlands and streams, many of which help feed drinking water systems. The Natural Resources Defense Council estimates this new rule could strip federal protections from 94 percent of U.S. wetlands and streams that do not flow continuously. This is a gutting of the Clean Water Act as we have known it.

What KWA is recommending you do by October 10: Submit comments to the EPA voicing your support of federal protections of wetlands, streams, and clean drinking water.
​Submit comments here.

Kentucky Waterways Alliance Comments on the Proposed Definition of “Waters of the United States”
Kentucky Waterways Alliance (“KWA”) opposes EPA and the Army Corps of Engineers’ September 2026 Supplemental proposal to further narrow the definition of “waters of the United States” (“WOTUS”) under the Clean Water Act.
 
The Clean Water Act was designed to protect the integrity of the Nation’s waters. This requires recognizing a basic hydrologic reality that rivers, tributaries, headwaters, wetlands, springs, and groundwater connections function together as watersheds. Pollution or destruction upstream does not stop there simply because a stream periodically stops flowing or a wetland lacks a permanent surface-water connection.
 
Federal jurisdiction has already been substantially narrowed by the Supreme Court’s Sackett decision, and EPA and the Corps implemented those limits through the amended 2023 WOTUS rule. That framework shows the agencies can comply with the Court while preserving meaningful protection for connected water systems.
 
What the New Proposal Would Do
The September 2026 Supplemental proposal does not replace the broader November 2025 WOTUS proposal. Instead, it adds narrower alternatives focused primarily on two key jurisdictional concepts: what qualifies as a “relatively permanent” water and what constitutes a “continuous surface connection” for wetlands, in an effect to establish a new “perennial” standard.
 
The remainder of the November 2025 proposal, including proposed changes involving interstate waters, ditches, prior-converted cropland, waste-treatment systems, groundwater, and other jurisdictional categories remains under consideration but is not substantively revised by the September supplement.
 
The most consequential new alternatives include:

• Tributaries: Limit “relatively permanent” waters essentially to perennial waters that contain standing or continuously flowing water throughout the year under ordinary conditions.
• Intermittent streams: EPA acknowledges most intermittent streams would not satisfy the proposed perennial standard, placing a large category of tributaries outside federal jurisdiction.
• Wetlands: Requires perennial surface water within the wetland that is continuously connected to another jurisdictional water so that it is difficult to determine where one ends and the other begins.
• Loss of wetland jurisdiction: EPA acknowledges the majority of currently jurisdictional adjacent wetlands would likely fail this standard because most wetlands do not contain perennial surface water.
• 30-day bright-line: Allow a water to remain “perennial” despite one temporary interruption of up to 30 consecutive days in a year under specified conditions. This concept would apply to both the tributary standard and the proposed continuous surface-water connection test for wetlands.

 
WOTUS determines the reach of major Clean Water Act protections governing pollution discharges, dredging, and filling. When a water falls outside WOTUS, those protections no longer apply.
 
Protect the Whole Watershed
KWA’s principal concern is the proposal narrows Clean Water Act protection in ways that do not reflect how water moves through a watershed and go beyond what is required by the Sackett decision.
 
Streams, wetlands, headwaters, springs, and groundwater are connected parts of the same system. The amended 2023 rule already demonstrates that Sackett can be implemented while recognizing those connections.
 
Further narrowing definitions would exclude waters that still affect downstream water quality, drinking-water supplies, flood resilience, and aquatic habitat. Protecting downstream water requires protecting the whole watershed that sustains them.
 
Why This Matters Especially in Kentucky
Kentucky has more at stake in this debate than most states.
 
The Commonwealth contains more than 92,000 miles of rivers and streams, and approximately 65% of Kentucky’s stream system is intermittent or ephemeral. Those waters are especially important in Kentucky’s karst landscape, where water moves between streams, sinkholes, caves, groundwater, and springs.
 
Kentucky has also lost roughly 80% of its historic wetlands, leaving about 360,000 acres. Those remaining wetlands filter pollution, store floodwater, replenish water supplies, and support fish and wildlife.
 
At the same time, Kentucky’s water quality is already strained. The Commonwealth’s 2024 Integrated Report found approximately 70% of assessed river miles and 87% of assessed lake acres impaired.
 
The proposal therefore places additional pressure on the very waters Kentucky relies on to sustain downstream rivers, drinking-water sources, flood resilience, wildlife, recreation, and economic activity.
 
Kentucky Cannot Simply Replace Lost Federal Protections
The impact is amplified by Kentucky law.

In 2025, Senate Bill 89 substantially tied Kentucky’s definition of protected state waters to federal WOTUS jurisdiction. As a result, Kentucky does not have the same independent state-law backstop available in states that retain broader state-based authority.
 
When federal jurisdiction contracts, Kentucky jurisdiction contracts with it.
 
The Kentucky Energy and Environment Cabinet previously estimated that alternatives in the November 2025 proposal could leave approximately 74% to 86% of Kentucky stream miles outside the protections at issue. Those figures do not measure the September supplemental proposal, but they demonstrate the scale of Kentucky’s exposure to further narrowing.
 
Kentucky is also downstream of numerous interstate watersheds. Pollution does not stop at state boundaries, making a meaningful federal baseline especially important to the Commonwealth.
 
The Costs Do Not Disappear When Regulation Does
Narrowing Clean Water Act jurisdiction does not eliminate the consequences of pollution, flooding, or waterway destruction. It shifts those costs.
 
Drinking-water utilities and customers will bear higher treatment costs. Communities will bear greater flood and recovery costs. Fisheries, wildlife, recreation, agriculture, tourism, and water-dependent industries will bear the consequences of declining water quality.
 
Clean water is not simply an environmental benefit. It is infrastructure and an economic asset.
 
Maintain a Strong and Workable Definition of WOTUS
KWA supports clear and predictable rules. But clarity should not be achieved by excluding functioning parts of watersheds from protection.
 
The amended 2023 rule already demonstrates the Supreme Court’s Sackett decision can be implemented while maintaining a workable federal definition. EPA and the Corps should retain that framework rather than adopting additional restrictions that would exclude most intermittent streams and the majority of currently protected adjacent wetlands.
 
More broadly, the United States needs a durable WOTUS definition that protects a meaningful federal baseline, reflects how watersheds actually function, and allows states to provide additional protections.

Kentucky’s major rivers are built from smaller waters. Because Kentucky has tied much of its own authority to WOTUS, further federal narrowing has an amplified effect here at home. KWA urges EPA and the Corps to retain the strongest workable definition of WOTUS permitted by the Clean Water Act and protect the watershed as a whole.