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Clean Water Act “Waters of the United States” Update
As highlighted in our recent Client Alert, Trump Administration Proposes Rule to Revise and Narrow Definition of Waters of the United States, on November 17, 2025, the Environmental Protection Agency and the U.S. Army Corps of Engineers (the “Agencies”) announced a proposed rule (the “Proposed Rule”) to revise and narrow the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA). During the 45-day comment public comment period for the Proposed Rule, the Agencies received upwards of 29,000 comments reflecting a broad range of views regarding the Proposed Rule. Despite many comments requesting an extension of the comment period, no extension was granted and the comment period closed on January 5, 2026, marking the beginning of the Agencies’ process to review the record and finalize the rule. In the coming year, we expect continued debate over the Proposed Rule, issuance of a final rule, potential litigation grounded in the issues raised during the comment period, and potential changes to state environmental regimes looking to fill regulatory gaps created by the federal rule.
Comments to the Proposed Rule provide insight into the coming debate and future potential litigation. Many organizations, such as the National Association of Home Builders, strongly support the Proposed Rule and highlighted the importance of adding a regulatory definition of “continuous surface connection,” establishing clear jurisdiction exclusions around ditches and wastewater treatment devices and aligning the definition of WOTUS more consistently with the Supreme Court’s decision in Sackett v. Environmental Protection Agency. Likewise, the American Public Works Association was generally supportive of the Proposed Rule, but questioned the Agencies’ definition of “wet season,” a new concept in the Proposed Rule for use in evaluating a “continuous surface connection.” Some organizations, such as the Pacific Legal Foundation (PLF), a public interest law firm focusing on individual and property rights, asked the Agencies to go even a step further. The PLF advocates that the Agencies should adopt an alternative approach to the Proposed Rule whereby WOTUS would be defined only to encompass traditional navigable waters, tributaries that directly flow into those waters, and wetlands with a continuous surface connection to such waters, as informed by Justice Thomas’s concurrence in the Sackett decision.
On the other end, there are many organizations and individuals that strongly oppose the rule, often focusing their comments on potential adverse environmental impacts and lack of scientific support for the framework adopted in the Proposed Rule. Some large environmental organizations have submitted comments critical of the Proposed Rule, claiming that it will significantly scale back protections for America’s waters. For example, the Environmental Protection Network (EPN), an organization comprised of former EPA career staff and political appointees, urged the Agencies to abandon the Proposed Rule and leave intact the 2023 Conforming Rule, which was promulgated by the Agencies in response to the Sackett decision. The EPN argues that the Proposed Rule, among other things, violates the purpose of the CWA to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters; proposes scientifically indefensible definitions of “relatively permanent flow,” “continuous surface connection,” “tributary,” and “wet season”; and misconstrues the term navigable waters. Based on comments submitted and public statements from these environmental organizations, it appears they are likely setting the stage for potential litigation over the rule if it is finalized in current form.
Beyond litigation, we may also see some states taking action to expand state regulation of surface waters to fill in the gaps created by the Proposed Rule’s narrowing of the WOTUS definition. For example, in response to the Sackett decision removing certain wetlands from federal jurisdiction, Colorado created a new state-level permitting program for dredge and fill activities designed to protect state water resources. Some have estimated that roughly 50 percent of state waters in Colorado lost federal protections as a result of the Sackett decision given the significant number of intermittent or non-contiguous waters in the state. This filling-the-gap approach may expand to other states, with different jurisdictions taking different approaches to protecting streams and wetlands and potentially making the regulatory landscape more complex.
Now that the 45-day comment period has ended, the Agencies will turn to reviewing the comments, responding to significant comments, and considering any changes to the Proposed Rule that may be warranted in a final rule based on comments received. As has occurred with prior WOTUS rulemakings, we expect litigation over the scope of the rule to ensue once it is finalized. The combination of the final WOTUS rule, rulings in litigation over the final rule, along with State’s efforts to step in and fill the gaps left by the final rule (or in anticipation of the final rule) could (once again) result in a shifting landscape for aquatic resource permitting in 2026.
If you have questions concerning EPA’s Proposed Rule or state regulation of waters and wetlands, please contact MGKF’s Sean Fahy, Todd Kantorczyk or Brenda Gotanda.
