The FCC’s Wireless Telecommunications Bureau (WTB) has released a public notice notifying tower builders of a recent change in the Clean Water Act’s (CWA) definition of “waters of the United States” (WOTUS) as defined in the Navigable Waters Protection Rule (NWPR). The change in the definition could affect tower builders with facilities requiring CWA permits from the US Army Corps of Engineers (Corps), including facilities where construction will involve significant change in surface features triggering the environmental assessment provisions of the FCC’s environmental rules. A federal court ruling vacated the NWPR, which has long been the subject of litigation, and remanded the rule to the Corps and the U.S. Environmental Protection Agency (EPA). The Corps has announced that it is interpreting the NWPR definition under the pre-2015 definition, which is much broader. While the Corps has stated that it will not reconsider permit decisions that relied on the NWPR before the Court’s vacatur, the Bureau encourages tower builders with permits to contact the Corps to ascertain the potential implications of the revised WOTUS definition. The Corps and EPA are currently involved in a rulemaking to adopt a new definition of WOTUS.