Storm Water and TMDLs: Backdoor Numeric Requirements in Storm Water Permits?

Be prepared for specific numeric requirements in storm water permits.

For more than two decades, storm water dischargers have complied with permits that impose vague general requirements for implementing best management practices (BMPs). Recently, there has been pressure to include numeric requirements in storm water permits. Numeric requirements would make it easier for agencies and environmental groups to identify which dischargers are violating permit requirements. Those dischargers can then be sued and forced to pay penalties and attorney fees. There has also been pressure to give teeth to TMDL-based requirements, which are intended to bring water quality in ambient streams up to the "fishable-swimmable" criteria established through water-quality standards. Vague general requirements in storm water permits are likely to be replaced with specific numeric requirements. As a result, dischargers may find that they must comply with numeric requirements that arrived with little or no warning. This topic will explain what TMDL-based storm water requirements are, how they are imposed by regulatory agencies, and what can be done about them.