Regulatory Alert: Proposed Revisions Could Affect NPDES Permit Conditions

Pennsylvania DEP Proposes Revisions to Water Quality Management Strategy Potentially Affecting NPDES Permit Conditions

The Pennsylvania Department of Environmental Protection (DEP) is proposing to revise portions of Pennsylvania Code, Title 25, Chapter 16, Water Quality Toxics Management Strategy; DEP’s water quality policy for regulating toxic substances in NPDES permits. (Published in the Pennsylvania Bulletin October 21, 2017.)  The water quality toxics management strategy provides DEP with guidance in establishment of water quality criteria for development of NPDES effluent limits, and provides analytical and detection limits for toxic substances.  The proposed changes to the strategy could impact NPDES permit holders who are discharging toxic substances, in the determination of future effluent limits and other permit conditions.  Toxic substances include Clean Water Act “Priority Pollutants” and other toxic substances DEP determines are of concern in wastewater discharges.  Heavy metals and some solvents are among the common toxic substances covered in this policy. Chapter 16 is updated regularly, and incorporates EPA guidance as well as DEP regulatory revisions and other data.

Currently proposed revisions to Chapter 16 include:

  • Clarification of endpoints, magnitude and duration relating to acute and chronic aquatic life protection.
  • Addition of the ECOTOX computerized database as a source for aquatic life information.
  • Addition of the availability of the Biotic Ligand Model to determine site-specific metals criteria.
  • Addition of Benchmark Dose Modeling as an alternative way of calculating adverse effect levels for human health criteria development, and deletion of references to certain sources for development of water quality criteria. EPA’s Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health is used as the source for method development.
  • Revision to exposure factors to reflect the latest scientific information, and to implement existing guidelines in EPA’s methodology for deriving human health criteria.
  • Relating to non-threshold effects (cancer); human health and aquatic life criteria; and special provisions for the Great Lakes System, language not applying to the Great Lakes System is proposed to be deleted.
  • Additional clarification to Whole Effluent Toxicity Testing (WETT) regarding requirements and implementation of WETT under Chapter 92a and Chapter 252.
  • Relating to analytical methods and detection limits, language is proposed to be deleted and site-specific criteria in Appendix A, Table 1A populated and maintained on DEP’s website. References to the EPA-approved analytical methods and guidelines are proposed to be added to this section.

DEP is accepting public comment on proposed revisions through December 29, 2017, and holding three public hearings on December 6, 8, and 14. For more information, see DEP’s website at

This regulatory alert was prepared by Julie Galbraith, Environmental Compliance Specialist at Liberty Environmental.