“Revised Definition of ‘Waters of the United States’” Published in Federal Register

September 14, 2023

On September 8, 2023, the “Revised Definition of ‘Waters of the United States’” was published in the Federal Register. This rule, created by the Environmental Protection Agency and United States Army Corps of Engineers, amends the agencies’ January 2023 Waters of the United States (WOTUS) definition, portions of which were rendered invalid based on a May 2023 Supreme Court decision in the Sackett v. Environmental Protection Agency case. 

The ruling made several changes to the definition, the most notable being:

  • Redefining “adjacent” to mean “having a continuous surface connection”
    • The term adjacent was revised to reflect that only adjacent wetlands or waterbodies with a continuous surface connection to a traditional navigable water (TNW) or a relatively permanent, standing, or continuously flowing tributary of a TNW are WOTUS. It is anticipated that this revision will result in significantly more non-WOTUS isolated wetlands.
  • Removing all references to the term “significantly affects”
    • The term “significantly affects” was removed in its entirety; therefore, significant nexus evaluation is no longer applicable to determine if a wetland or waterbody is a WOTUS.
  • Revising the term “tributary”
    • The term tributary was revised to only include relatively permanent, standing, or continuously flowing waterbodies. The preamble of the amendment referenced the 2006 Rapanos v. United States decision where the Supreme Court addressed the scope of WOTUS. Based on this language, pointing to the discussion of “relatively permanent” in the Rapanos case, it is anticipated that most ephemeral streams may no longer be regulated as WOTUS. 
  • Removing “interstate wetlands” from the defined list of WOTUS categories
    • “Interstate waters” has been revised to clarify that interstate wetlands are no longer interstate waters, and “wetlands” and “streams” are no longer “additional waters.” According to the EPA, under Sackett, the provision authorizing wetlands to be jurisdictional simply because they are interstate is invalid.

The January 2023 Rule, which aimed to broaden the definition of WOTUS, remains enjoined in 27 states due to ongoing litigation. Therefore, according to the agencies, the January 2023 Rule and this conforming rule will be implemented in 23 states, the District of Columbia, and the U.S. Territories. Until further notice, the agencies are interpreting “waters of the United States” consistent with pre-2015 regulations and the Supreme Court’s decision in Sackett in the 27 states where the January 2023 Rule remains enjoined.

Regulatory developments and litigation relative to the definition of WOTUS have been frequent and contentious, and further changes are still anticipated. Thankfully, CEC has subject matter experts who understand these regulations down to the state and local levels. If you would like to further understand how the changing WOTUS definition, Clean Water Act, or other regulations apply to you or your project, please don’t hesitate to reach out.


Ray Ewing | Corporate Ecological Sciences Practice Lead
rewing@cecinc.com, 412.249.2363




Rob Geho | Principal
rgeho@cecinc.com, 614.310.1044

About the Author

CEC Staff

Headquartered in Pittsburgh, Civil & Environmental Consultants, Inc. (CEC) provides comprehensive market-oriented consulting services to advance client strategic business objectives. CEC is recognized for delivering innovative design solutions and integrated expertise in air quality, civil engineering, ecological sciences, environmental engineering and sciences, manufacturing infrastructure services, survey/geospatial, waste management, and water resources.

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