In January 2015, the Sixth Circuit held that a defendant’s compliance with the terms of its National Pollutant Discharge Elimination System (“NPDES”) general permit would effectively “shield” that defendant from claims filed under the citizen suit enforcement provisions of the Clean Water Act.  Sierra Club v. ICG Hazard. 

In 2001, the Fourth Circuit established a two-part test to determine applicability of a permit shield in cases involving an individual permit.  Piney Run Preservation Association v. County Commissioners of Carroll County, MD.  The Piney Run decision held that an individual permit holder could be shielded from liability for discharges of pollutants not specifically listed in the permit provided that: (1) the discharges at issue were “within the reasonable contemplation” of the regulator during the permit application process; and (2) the permittee complied with the express terms of the permit.

The ICG decision by the Sixth Circuit extends this permit shield defense to general permits as well as individual permits.  The Piney court reasoned that with the shield, “compliance would be impossible and the potential for litigation limitless” because of “the practical impossibility of identifying and limiting every potential compound or chemical in a given discharge.”  The ICG court held that the same reasoning applied to general permits because “the permitting authority would not only need to identify the many pollutants that a single polluter could discharge, but all of the pollutants and combinations of pollutants that could be discharged by all polluters that may later fall under the general permit.”  It further reasoned that although “the agency cannot know which specific facilities will seek coverage under the general permit . . . the authority can contemplate the pollutants that may be discharged generally from pollutants that may later be covered by the general permit.”