On March 28, 2024, the United States Environmental Protection Agency (USEPA) published a final rule (the 2024 Rule) that expands the number of facilities required to develop a facility response plan for a worst-case discharge of certain hazardous substances or the threat of such a discharge.[1] Prior to this 2024 Rule, the Clean Water Act (CWA) regulations required an owner or operator of a facility to prepare and submit to USEPA a facility response plan for responding to a worst-case discharge of oil. This 2024 Rule, however, expands the scope of the regulation to also require facilities to prepare and submit a facility response plan for the discharge (or threat of discharge) of CWA-listed hazardous substances.