Stormwater TMDL Compliance - A Case Study of Implementation Strategies Used in Two Coasts

Across the country, many public agencies, including state DOT highway divisions, which own and operate municipal separate storm sewer system (MS4), are facing increasing pressure in meeting the EPA's TMDL or Waste Load Allocation (WLA) requirements. TMDL/WLA implementation is creating additional work load and financial burden for many highway agencies as they try to meet conditions of their existing NPDES/MS4 permits with limited resources. EPA enforcement of TMDL compliance varies from region to region; some were expressed in TMDL implementation plans, while others impose numeric WLAs to the MS4 permit holders. The regional variation of the TMDL requirements influences the strategies and approaches the MS4 permittees choose in TMDL implementation. This paper highlights the TMDL compliance strategies of four different agencies; located miles apart, each have their own unique features yet all utilize a multi-set tool box to achieve compliance.