Preliminary Plan 15 is the first effort by EPA to address PFAS releases at manufacturing facilities by setting discharge limits and treatment standards. EPA’s past actions to address PFAS have included proposals concerning PFAS in drinking water as well as the release of a Toxicity Assessment for Perfluorobutane Sulfonic Acid (“PFBS”), a member of the larger PFAS group.BackgroundSection 304(b) of the Clean Water Act (33 U.S.C. § 1314(b)) requires EPA to annually review, and if necessary, revise ELGs.1 ELGs are technology-based wastewater discharge standards that are developed by EPA on an industry-by-industry basis. The standards for direct dischargers are then incorporated into National Pollutant Discharge Elimination System (“NPDES”) permits issued by the states and EPA.

The guidance provides an explanation of how to use what is referenced in the Opinion as:. . . a new statistical method called the Test of Significant Toxicity (TST).A trade association, whose members include California municipal agencies operating wastewater treatment plants (collectively “Plaintiffs”), filed suit in the United States District Court (Eastern District of California) (“Court”) challenging EPA’s use of the TST. They argued that EPA’s use of TST violated the APA when the State of California’s application to use the TST as an “alternative test procedure” for permits under 33 U.S.C. § 1314(h) was approved by EPA.EPA subsequently withdrew its approval of California’s alternative test procedure and the Court dismissed the case as moot.Plaintiffs brought another action alleging EPA had violated APA by issuing the TST guidance without following notice-and-comment rulemaking procedures.