WATERSHED-BASED NPDES PERMITTING WITH A FOCUS ON WET WEATHER INTEGRATION

Interest in managing water resources through watershed approaches has been increasing over the last decade from the perspective of NPDES authorities, permit holders and others. In December 2002, the EPA Office of Water Assistant Administrator issued a policy memo entitled Committing EPA's Water Program to Advancing the Watershed Approach (USEPA 2002a). This policy reaffirmed EPA's commitment to the watershed approach and energized efforts to fully integrate the approach into program implementation. Subsequent supporting policy statements and guidance reinforced EPA's commitment to watershed-based permitting. In addition, comments and discussions with stakeholder groups have helped direct EPA's current and future efforts with regard to watershed-based permitting.EPA has been evaluating the best course of action for controlling urban wet weather discharges on a watershed basis. Wet weather discharges include storm water 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 can be extremely variable from one wet weather event to the next with respect to frequency, duration, volume and pollutant load. This unpredictability and variability makes it difficult for local environmental agencies to manage wet weather discharges. It also makes it difficult for NPDPES permitting authorities to draft permits to address wet weather discharges.The paper and presentation will describe past and current efforts by EPA to advance watershed-based permitting approaches. It will provide examples that highlight different approaches that have been implemented in watersheds around the country. The paper and presentation will also provide information on EPA's work to integrate other watershedbased efforts related to control of urban wet weather discharges. That is, storm water, CSOs, SSOs, and management of peak wet weather flows at POTWs.