APPROACHING TMDLS USING ARISTOTLE AS A TEACHER: AN ADAPTIVE WATERSHED MANAGEMENT APPROACH

This paper describes a non-prescriptive approach for certain situations requiring a total maximum daily load (TMDL). This approach, adaptive watershed management, combines concepts from adaptive management and watershed management to address the various uncertain elements in a TMDL. It provides a process to be progressively implemented over a specific timeframe, until water quality standards are attained. The paper discusses how adaptive watershed management allows initial progress to be made and additional information to be collected to definitively define a TMDL number and to specify final control actions.A description of how the adaptive watershed management approach differs from the traditional TMDL approach is provided. This approach improves upon the phased TMDL approach by requiring more rigorous follow-up and commitment. The paper demonstrates how the recommended approach ensures that water quality standards will be met and that sufficient time and resources are allotted to assess improvements, re-evaluate conditions, and update actions until designated uses are restored. The feedback loops within the approach allow managers to proceed with implementation of controls in a progressive manner, avoiding unproductive and irresolvable debate over uncertainty in the numeric value of the TMDL or the efficacy of the controls.Situations where adaptive watershed management approach should, and should not be applied, are identified. Applications include situations that have significant uncertainty, have unclear linkages between stressors and loads, require a long timeframe for water quality improvements to occur, or involve significant costs, such as situations that are dominated by nonpoint source loads or involve narrative standards. Discussions of the history of adaptive management (“learning by doing”) and the current use of adaptive management in the TMDL program are provided.The calls for a more comprehensive approach are also discussed, as well as the considerations and obstacles that need to be addressed. Considerations include the development of an implementation plan and schedule; a monitoring and modeling plan; a watershed management plan; a funding strategy; a stakeholder involvement plan; and a decision plan. Potential obstacles associated with effectiveness; equity; regulatory programs; and resources are addressed.