The U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (Corps) announced, on Sept. 3, that they would no longer implement the then-current definition of “waters of the United States” (WOTUS) effective immediately. Instead, they have reverted back to the pre-2015 permitting regime, relying upon the 1986 definition of WOTUS, as interpreted by the Corps and the EPA in guidance documents issued following two seminal U.S. Supreme Court opinions. The EPA and the Corps are applying this change in the WOTUS definition nationwide. The switch follows an Aug. 30 order from the U.S. District Court for the District of Arizona, which remanded and vacated the definition of WOTUS promulgated by the Trump administration in 2020 (commonly referred to as the Navigable Waters Protection Rule (NWPR)) in the case of Pascua Yaqui Tribe v. U.S. Environmental Protection Agency.

Importance of the Definition of WOTUS

The definition of WOTUS identifies which waters are federally regulated under the Clean Water Act (CWA), and, therefore, determines when a federal permit is required for projects involving dredging or filling of a waterbody (i.e., a Section 404 permit) or discharges into a waterbody (i.e., a NPDES permit). The WOTUS definition also affects federal spill reporting and spill prevention planning.