Agencies Narrow Scope of WOTUS Definition Following Sackett

Following the U.S. Supreme Court’s landmark decision in Sackett v. EPA (2023), the EPA and Army Corps of Engineers (Corps) narrowed the definition of “Waters of the United States” (WOTUS) under the Clean Water Act. EPA and the Corps issued a conforming WOTUS rule in September 2023, which became effective in Arizona and excluded many previously regulated features, including ephemeral drainages commonly found in arid regions. Reinforcing this shift, EPA and the Corps also issued joint guidance in March 2025, clarifying that wetlands must be immediately connected without intervening barriers like uplands, berms, or dikes to meet the WOTUS definition.

EPA and the Corps recently launched a stakeholder process to refine WOTUS definitions further, seeking public comment on how best to identify jurisdictional waters, tributaries, and ditches. This process includes a listening session scheduled for May 1, 2025, at 6:30 AM Arizona time, which you can register for here.

These developments mark a notable change in how federal water protections are interpreted and implemented, creating implications for landowners, developers, and environmental regulators, particularly in regions like the Southwest.