A Sea Change Ahead for Bacteria TMDL Implementation
MS4 agencies in many watersheds across the state face an enormous financial burden in meeting bacteria TMDL wasteload allocations and/or numeric limits. In many cases, dry weather compliance deadlines have passed and wet weather deadlines are fast approaching. The required structural BMPs that have been modeled to control/reduce bacteria can cost 100’s of millions of dollars to implement, and in some cases there remains uncertainty as to whether compliance will be achieved. For multiple bacteria TMDLs in Southern California, MS4 agencies and regulators are coordinating to develop an alternative compliance pathway that focuses on control of human waste sources. By strategically finding and eliminating the sources associated with the greatest health risk, recreational health outcomes can be achieved at a fraction of the cost compared to structural BMPs targeting fecal indicator bacteria. This pathway – and its health risk outcomes – thus represents a preferred alternative for the recreating public, environmental NGOs, MS4 agencies, and regulators alike.
Tools for the reliable identification and quantification of bacteria specific to human waste are now available through microbial source tracking (MST). The pathogens responsible for illness from recreational activities can now also be reliably detected and health risks can be estimated through quantitative microbial risk assessment (QMRA). MST and QMRA are recognized by the USEPA and SWRCB, verified and validated through numerous published studies throughout California, and guidance on their use to develop alternative Water Quality Criteria is forthcoming. However, to meet the approaching compliance deadlines of many bacteria TMDLs, action must be taken soon to begin finding and eliminating human sources and gathering data to support the development of site-specific objectives (SSOs) once human waste sources – particularly controllable infrastructure contributions, like illicit connections and sewer leaks – have been controlled.
This presentation will outline a TMDL compliance pathway that is being tested now by multiple Regional Boards and that focuses on the reduction of human fecal sources. Examples will be provided of how this approach is currently being pursued by MS4 agencies for bacteria TMDL compliance in Ventura County, Los Angeles County, and South Orange County. By eliminating the human waste contribution and associated pathogens rather than all fecal indicator bacteria, health risks may be reduced more effectively and at a much lower cost compared to the implementation of structural BMPs. The successful implementation of this higher return on investment pathway will have implications for bacteria Water Quality Standard compliance across California and throughout the United States.
Brandon Steets is a licensed chemical engineer, a Senior Principal with Geosyntec Consultants, an industrial stormwater Trainer of Record, and a member of the State’s Clean Beaches Task Force. He has worked for over 17 years on challenging stormwater projects that include modeling, monitoring, source investigation, BMP planning, treatment BMP design, NPDES permitting, and strategic regulatory services.
Dr. Jared Ervin is an engineer with Geosyntec Consultants in water and natural resources with more than 6 years experience managing pollutant source tracking projects. Dr. Ervin received his B.S. and M.S. in engineering from Cal Poly San Luis Obispo and his Ph.D. in environmental engineering from Utah State University. Prior to joining Geosyntec in 2015, Dr. Ervin was a postdoctoral researcher at the University of California, Santa Barbara in pollutant source tracking.