Regulatory Tracker

Publicly Owned Treatment Works Hazardous Air Pollutant Standards

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Why It Matters

Sewage treatment plants can release numerous hazardous air pollutants, which pose significant health risks to nearby communities (EPA has identified acetaldehyde, acetonitrile, chloroform, ethylene glycol, formaldehyde, methanol, methylene chloride, tetratchloroethylene, toluene, and xylenes as the primary hazardous pollutants emitted from publicly owned treatment plants). To limit the release of these pollutants during the wastewater treatment process, EPA established emission standards for large publicly owned sewage treatment plants.


Dec. 27, 2016 EPA proposes changes to the emission standards for large publicly owned sewage treatment plants (also known as POTWs) to make the standards more effective. These standards were last substantively updated in 2002. The agency proposes, among other modifications: to require that all affected plants develop and implement pretreatment programs; to require that certain plants meet a calculated emission limit; and to apply the standards to additional aspects of the sewage treatment process (such as sewage collection systems). The proposal is responsive to findings of a risk and technology review for large publicly owned treatment plants. The review concludes that that the public health risks from these facilities are “low and well within acceptable limits.”

Trump Era

Oct. 26, 2017 EPA finalizes emission standards and the residual risk and technology review for large publicly owned treatment plants. The final rule does not include substantive changes to the emission standards for treatment plants. It does include certain administrative changes and an annual electronic reporting requirement for affected plants. It extends the initial notification requirements to existing sources. It also clarifies that standards apply during startup, shutdown, and malfunctions, consistent with Sierra Club v. EPA, 552 F.3d 1019 (D.C. Cir. 2008).

The rule does not take action on more substantive changes in the 2016 proposal. For example, EPA does not finalize the proposal for pretreatment programs and limiting emissions from collection systems. It also declines to change the requirements for existing treatment facilities who accept industrial facilities’ wastewater or extend the hazardous air pollutant fraction emission limits to existing treatment facilities. The final rule does not anticipate any emissions reductions, instead focusing on clarity for compliance purposes.