Meeting the Regulatory Challenge: The Effect of TMDLs on Municipal Stormwater Permits and Watershed Management

Abstract

The National Pollutant Discharge Elimination System (NPDES) stormwater program is taking on fresh significance now that Total Maximum Daily Loads (TMDLs) have begun to be implemented nationwide. This is particularly where states have adopted a “watershed approach” for implementing TMDLs. TMDLs prescribe pollutant load reductions specifically for Municipal Separate Storm Sewer System (MS4) outfalls. Further, watershed-based reductions of pollutants will apply to municipal stormwater permits on a “jurisdiction -wide” basis, providing the necessary mechanism to assure that reductions are implemented. In order to meet this incredible challenge, municipal permittees, in coopera tion with the permitting authority, will be required rethink the way that watersheds are managed. Methods will likely appropriate comprehensive, holistic solutions involving non-structural as well as structural BMPs. It will also involve the re examination of many of the practices that cities and counties currently perform to meet their NPDES stormwater requirements. Programs will shift their emphasis from simply implementing BMPs to a system that better quantifies pollutant reductions that are associated with management practices. New technologies will have to be tried, innovations explored, and a new paradigm will need to be embraced regarding the reduction of pollutants in the watershed. This paper provides a former regulator’s perspective on what may be expected over the coming years, as TMDLs become a reality. It will also explore several creative new ideas for dealing with pollutant reduction requirements on a watershed basis, and how those ideas may be incorporated into MS4 permits in the futur e.