MEETING THE URBAN WET WEATHER CHALLENGE: AN APPROACH FOR NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) PERMITTING

Discharges that result from rainfall and snowmelt (wet weather events) include storm ater runoff, combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), and peak wet weather flows at publicly-owned treatment works (POTWs). Wet weather discharges are intermittent, somewhat unpredictable, and not easily characterized. They are extremely variable from one wet weather event to the next with respect to frequency, duration, and volume. This unpredictability and variability makes it difficult for local environmental agencies to manage wet weather discharges. It is also makes it difficult for National Pollutant Discharge Elimination System (NPDES) permitting authorities to draft permits to address wet weather discharges. In order to assist local environmental agencies and NPDES authorities accomplish their missions in a economical yet responsible manner, the Environmental Protection Agency (EPA) has begun work on a strategy to address management of wet weather flows in a holistic manner. The strategy will consider innovative approaches that provide flexibility for management of wet weather programs.Addressing wet weather discharges in a holistic manner can provide for greater efficiency, more comprehensive planning, and less redundancy among permitting requirements. Nontraditional approaches may be required to address the challenges posed by wet weather discharges. Such challenges must be addressed on several fronts:Ensuring that the existing framework of regulation and policy is fully implemented for those discharges covered by existing programs.Adjusting the existing regulation and policy framework to reflect the difficult decisions municipalities face in controlling episodic, variable, and largely unpredictable wet weather discharges.Supporting flexible local decision-making to achieve watershed objectives in the most cost-effective manner.This paper will first provide a brief regulatory and policy background on the principal wet weather discharges regulated under the NPDES program. This paper will discuss EPA's work toward developing a strategy for integrating wet weather programs and addressing the control of wet weather discharges through NPDES permits. That is, storm water, CSOs, SSOs, and management of peak wet weather flows at POTWS.