In May 2018, the Environmental Protection Agency (EPA) held a two-day National Leadership Summit ("Summit") on per- and polyfluoroalkyl substances (PFAS). The EPA announced that the Agency would begin the necessary steps to propose designating perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as "hazardous substances" through one of the available statutory mechanisms, including potentially under section 102 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). CERCLA, commonly known as Superfund, provides the Federal Government with the authority to respond to releases or threatened releases of hazardous substances, and to releases or threatened releases of pollutants or contaminants that may present an imminent and substantial danger to public health or welfare. CERCLA also provides EPA with enforcement authority and establishes liability for releases or threatened releases of hazardous substances. Listing PFAS as CERCLA "hazardous substances" will expand EPA's response and enforcement authorities for PFAS releases, along with CERCLA liability for such releases. On February 14, 2019, EPA's Acting Administrator Andrew Wheeler announced EPA's PFAS Action Plan, which responds to extensive public interest and input the agency has received over the past year and represents the first time EPA has built a multi-media, multi-program, national communication and research plan to address an emerging environmental challenge like PFAS. EPA's Action Plan identifies both short-term solutions for addressing these chemicals and long-term strategies that will help provide the tools and technologies States, Tribes, and local communities need to provide clean and safe drinking water to their residents and to address PFAS at the source--even before it gets into the water. This rulemaking effort is one of the actions mentioned in the PFAS Action Plan.