National Association of Metal Finishers v. United States Environmental Protection Agency

Clean Water Act (CWA) § 307(b) authorized the Environmental Protection Agency (EPA) (defendant) to set pretreatment standards for an industrial user’s discharge of pollutants that would flow through a publicly owned treatment works (POTW). The provision barred discharge of pollutants that would interfere with or pass through the POTW. Section 307(c) stated that the purpose of the pretreatment standards was to ensure that discharge sent to a POTW did not violate the POTW’s permit. The CWA’s legislative history stated that pretreatment requirements were not intended to substitute for effective treatment by the POTW. The EPA had regulations implementing § 307(b), including 40 C.F.R. § 403.5(a), the prohibited-discharge standard. The prohibited-discharge standard barred dischargers from introducing pollutants that passed through a POTW or interfered with a POTW’s operation or performance. In a 1978 rulemaking, the EPA proposed adding a safe harbor for disruptions to the POTW caused by dischargers otherwise in compliance with discharge regulations. However, amendments finalized in 1982 did not include the safe harbor. As proposed, interference was redefined as a disruption of POTW operations that caused or significantly contributed to either a violation of the POTW’s permit or a POTW’s use or disposal of sludge. A user significantly contributed to a violation or a sludge disposal problem by discharging daily pollutant loads greater than those allowed by the POTW contract or by law, by discharging wastewater differing from the user’s average discharge, or by knowing or having reason to know that its discharge would result in a POTW permit violation or sludge problem. The National Association of Metal Finishers (NAMF) (plaintiff) sued, arguing that the 1982 definition of interference was inconsistent with the CWA because a discharger could be held liable simply for discharging more wastewater than usual even if the POTW’s permit violation or sludge problem was caused by another discharger or by a fault at the POTW. The EPA argued that the new definition did require the EPA to show that a discharger’s waste led or gave rise to, i.e., caused, a problem for the POTW.