On September 8, 2023, the U.S. Environmental Protection Agency and U.S. Army Corps of Engineers (ACE) published a final rule that revises the definition of “waters of the United States” (WOTUS). ACA has been involved in this process since 2015 because of the uncertainty in the definition of WOTUS, since the pre-2015 definition has been challenged in court and reconsidered several times.

This final rule, which took effect upon publication, conforms the definition of WOTUS to the U.S. Supreme Court’s decision from May 25, 2023, in Sackett v. Environmental Protection Agency. Although the agencies’ recent amendments to the definition of WOTUS were not directly before the Supreme Court in that case, the decision invalidated certain aspects of those amendments. The final EPA-ACE rule revises key aspects of the regulatory text to conform with the Supreme Court decision to provide more clarity in protecting federal waters while advancing infrastructure projects and encouraging economic and agricultural activities.

The changes to the definition of WOTUS include removing the significant nexus standard from consideration when identifying tributaries and other waters as federally protected; redefining the definition of “adjacent”; clarifying which wetlands are protected under the Clean Water Act; and clarifying the types of features that can be considered “additional waters.” These amendments do not change the eight exclusions from the definition of WOTUS. Furthermore, the changes to the definition of WOTUS do not affect the longstanding activity-based permitting exemptions allowed under the Clean Water Act.

Additional information can be found on EPA’s website at https://www.epa.gov/wotus/revising-definition-waters-united-states.

Contact ACA’s Rhett Cash or Suzanne Chang for more information.