Ten Things to Know About the Proposed 2025 WOTUS Rule

On November 20, 2025, the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (USACE) released a pre-publication of a Proposed Rule further refining the definition of waters of the United States (WOTUS) to conform with the U.S. Supreme Court’s decision in Sackett v. EPA issued on May 25, 2023. As stated in the EPA’s factsheet, the Proposed WOTUS Rule:

“…would fully implement the Court’s direction by ensuring federal jurisdiction is focused on relatively permanent, standing or continuously flowing bodies of water—such as streams, oceans, rivers, and lakes—and wetlands that are connected and indistinguishable from such waterbodies.”

The definition of WOTUS has been debated since the adoption of the Clean Water Act (CWA) in 1972. Over several decades, regulatory agencies and courts, including the U.S. Supreme Court, have made numerous efforts to interpret the jurisdictional reach of WOTUS under the CWA.

More information about the rule is available on the EPA’s webpage: Updated Definition of Waters of the United States.

Below are 10 things you should know about the Proposed WOTUS Rule:

1. Definitions

The Proposed WOTUS Rule refines definitions for important terms used in WOTUS determinations. We’ve provided them below for easy reference with a few notes from our initial analysis.

Relatively Permanent: “standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season.”

• Analysis: Ephemeral waters (i.e., those with surface water flowing or standing only in direct response to precipitation) are not jurisdictional because they are not relatively permanent. Intermittent streams that do not flow the entirety of the wet season would no longer be jurisdictional. The agencies acknowledge that surface hydrology may not always exactly overlap with the wet season (e.g., snowpack melt; delayed water table rise due to seasonal precipitation patterns).

Wet Season: “extended periods of predictable, continuous surface hydrology occurring in the same geographic feature year after year in response to the wet season, such as when average monthly precipitation exceeds average monthly evapotranspiration.”

• Analysis: Surface hydrology would be required to be continuous throughout the entirety of the wet season. Agencies propose using the Antecedent Precipitation Tool as the primary source for identifying the wet season on a place-by-place basis. Delineations will need to be targeted during the wet season to reduce uncertainty or the need for multi-visit delineations.

Continuous Surface Connection: “having surface water at least during the wet season and abutting (i.e., touching) a jurisdictional water.”

• Analysis: Wetlands, ponds, lakes require both 1) abutment of a relatively permanent water], and 2) having surface water at least during the wet season (saturation or high water table are not enough to meet this requirement). Only portions of a wetland with continuous surface hydrology uninterrupted throughout the wet season are jurisdictional, regardless of wetland scope or size. Mosaic wetlands are no longer “one wetland” but individual wetlands that must meet both new criteria. Culverts do not sever jurisdiction if it extends the relatively permanent water. Culvert must have an ordinary high water mark.

Tributaries: “Relatively permanent tributaries include rivers, streams, lakes, ponds, and other standing or continuously flowing bodies of surface water that are standing or continuously flowing year-round or at least during the wet season, that have a bed and banks, and connect to a downstream traditional navigable water or the territorial seas, either directly or through one or more waters or natural or artificial features that convey relatively permanent flow.”

• Analysis: For tributaries with relatively permanent and non-relatively permanent reaches, the non-relatively permanent reaches would sever jurisdiction of upstream reaches under the Proposed WOTUS Rule, except where the tributary is part of a water transfer currently in operation.

2. Interstate Waters

The Proposed WOTUS Rule removes interstate waters as a standalone condition for jurisdiction under the CWA. However, the agencies note that only 15 Approved Jurisdictional Determination (AJDs) in the last 10 years have been identified that were based solely on the interstate category.

3. Exclusions

The Proposed WOTUS Rule clarifies several exclusions from CWA jurisdiction as summarized in the table below.

Waste Treatment System: “all components of a waste treatment system designed to meet the requirements of the Clean Water Act, including lagoons and treatment ponds (such as settling or cooling ponds), designed to either convey or retain, concentrate, settle, reduce, or remove pollutants, either actively or passively, from wastewater prior to discharge (or eliminating any such discharge).”

• Analysis: This exclusion represents minor clarifying changes to current practice that are unlikely to result in major changes to regulatory practices.

Prior Converted Cropland: “any area that, prior to December 23, 1985, was drained or otherwise manipulated for the purpose, or having the effect, of making production of an agricultural product possible.”

• Analysis: An area is no longer considered prior converted cropland for purposes of the CWA when the area is abandoned and has reverted to wetlands. Abandonment occurs when prior converted cropland is not used for, or in support of, agricultural purposes at least once in the immediately preceding 5 years. Formal designation of prior converted cropland by the U.S. Department of Agriculture is not required, although documenting historic use of a tract is imperative for designating “agricultural purposes” and exemption. Rice and crayfish production areas are not jurisdictional.

Ditch: “A constructed or excavated channel used to convey water.”

• Analysis: Channelization or relocation of a tributary [RPW] does not modify the jurisdictional status of that water. Ditches that carry relatively permanent flow, but were dug wholly within uplands, are not jurisdictional. Interface with jurisdictional water does not make a ditch WOTUS. Channelized (a)1 waters, and intermittent and perennial (RPW) waters are not considered “ditches” and do not qualify as exempt.

Groundwater: Water “drained through subsurface drainage systems.”

• Analysis: Consistent with long-standing policy. States retain authority to regulate groundwater.

4. Importance of State Programs

Many states have programs to regulate “waters of the State.” The agencies estimate that at least 24 states regulate surface waters or dredge and fill activities more broadly than the Proposed WOTUS Rule. In addition, many states and localities across the United States are developing new state regulations to address aquatic resources. SWCA will be following these developments closely to ensure our regulatory experts and aquatic resource specialists comply with the changing regulations. Our teams can help evaluate state regulations to determine whether additional permitting would be needed beyond the federal requirements.

Figure 1. States with Regulatory Protections Broader than the Proposed Rule* Source: Regulatory Impact Analysis for the Proposed Updated Definition of Waters of the United States Rule

5. Regulatory Impacts

The agencies have completed a Regulatory Impact Analysis for the Proposed WOTUS Rule to evaluate the potential impacts of the proposed changes in reducing the scope of jurisdictional waters. The reduction in permit activity is projected to be greatest for the Section 404 Dredge and Fill permitting program, administered by the USACE and EPA. Agencies estimate that approximately 17.36 million acres of wetlands may retain jurisdictional status representing 19% of the 90.91 million acres of wetlands mapped in the National Wetlands Inventory. The Proposed WOTUS Rule will also reduce the scope of federal jurisdiction for other CWA programs, including Section 402 (National Pollutant Discharge Elimination System permitting), Section 303 (water quality standards, assessment, and total maximum daily loads), Section 311 (oil spills), and Section 401 (water quality certifications).

6. Delineation Procedures

The Proposed WOTUS Rule does not fundamentally change field delineation methods for wetlands, but it will change how those delineations are used to determine jurisdiction. Some adjustments to wetland field delineations include the need to map surface water lines fully within a wetland complex and the importance of conducting delineations during the wet season to reduce uncertainty.

7. Implications for Projects

The agencies have outlined methods to evaluate the impact of the new rule across the country. SWCA is prepared to apply these methods to individual projects. SWCA experts and project managers can help you to understand how these proposed changes may present challenges and opportunities for your current and future projects and business. We can assist you in reviewing the implications of the new ruling on your project through the following analyses:

• Using the National Hydrography Dataset Plus and the National Wetlands Inventory, screen the probability of changes in jurisdiction using the new definition and the draft methods outlined by the agencies in the Regulatory Impact Analysis that accompanied the pre-publication notice.
• Evaluate whether the original delineation was completed during the wet season and/or analyze historic imagery to determine the probability of water being present during the wet season.

8. Previous Regulatory Decisions

Project proponents may request revised delineations to limit the scope of jurisdiction for ongoing projects, even for situations with AJDs (depending on USACE review time frames). SWCA can assist with review of previous AJDs and help you to determine whether revisiting the decision would be strategically beneficial for your project.

9. Comment Period

The agencies are accepting comments on the Proposed WOTUS Rule for 45 days. Tips for preparing effective public comments are available at Regulations.gov. SWCA can also help you craft impactful and actionable comments for agency consideration in shaping any final rule changes.

10. What’s Next?

We are expecting litigation shortly after the rule goes into effect and regional guidance from the agencies in 2026. In addition, many states and localities across the United States are developing new state regulations to protect aquatic resources. SWCA will be following these developments closely to ensure our regulatory experts and aquatic resource specialists comply with the changing regulations.

For more information on the Proposed WOTUS Rule, please reach out to your project manager or any of SWCA’s regulatory and aquatic resource experts to the left to discuss.