EPA's New Technical Guidance for National Pollutant Discharge Elimination System (NPDES) Watershed-Based Permitting

For the past several years, EPA has been developing "technical guidance" to add to the December 2003, EPA Watershed-Based National Pollutant Discharge Elimination System Permitting Implementation Guidance [EPA 833-B-03-004]. This "technical guidance" expands on the information in the Implementation Guidance and also addresses many comments received during the public review phase of the Implementation Guidance. During the public review process, many commenters requested more detailed information on how to produce watershed-based permits and how to address specific situations that were considered beyond the scope of basic implementation processes. The decision was made to address these issues in future guidance and that is what is done through this new guidance.The new guidance is made up of three distinct pieces that recognize there is no one single approach. The watershed approach is characterized by the use of a dynamic process to identify and assess problems holistically and implement site-specific solutions to achieve watershed goals. Therefore, the process for integrating the NPDES permitting program into a larger watershed management system means developing and utilizing a watershed-based analytical approach to coordinate NPDES activities with other water quality activities. A watershed-based analytical approach is the groundwork data collection and analysis conducted to support the development and issuance of NPDES permits that consider the diverse pollutant sources and stressors located within a defined geographic area (i.e., watershed boundaries). The primary difference between a watershed permitting analytical approach and the more common historical approach to permitting is that the watershed permitting analytical approach considers the impact of multiple pollutant sources and stressors, including nonpoint source contributions. In contrast, the historical approach simply uses an aggregate background load. A watershed permitting analytical approach also considers watershed goals throughout the permitting process.The conclusions reached through the watershed-based analytical approach are then implemented through a broad range of possible NPDES implementation options to achieve watershed goals. These options extend beyond the traditional approach of developing and issuing a single NPDES permit to an individual point source discharger. This broader view of NPDES implementation options is referred to as the NPDES watershed framework, and the NPDES watershed framework serves as a structure to manage implementation of the NPDES program on a watershed basis. The framework provides a variety of permitting options and tools that can be used to implement a watershed approach. The specific permitting options and tools used in the framework will depend on the characteristics of the watershed and the permitting context.This paper and presentation will further discuss the concepts of a watershed permitting analytical approach and an NPDES watershed framework, including several permitting tools and options that a framework may include. Specifically, the presentation will describe the set of tools EPA has developed that are the new "technical guidance." The set of tools include three:First is the FrameworkThis piece includes three appendices that contain forms to help NPDES authorities• Appendix A: Stakeholder Involvement in a Watershed Permitting Analytical Approach and an NPDES Watershed Framework• Appendix B: Watershed Data Gap Assessment Worksheet• Appendix C: Keep Water Out Of Sewer Systems Tool Instructions and FormSecond is the GuideThis piece includes 2 appendices that contain forms to help NPDESAuthorities in implementing a watershed-based permitting approach• Appendix D: Example Supplemental Effluent Limit Table• Appendix E: Sample Watershed-based Permit DMRsThird are the Case StudiesThe paper and presentation will also highlight EPA's current activities in to assist NPDES permit writers and permittees throughout implementation of a watershed approach. This guidance builds on the existing Policy and Implementation Guidance that are already available to the public.