Coupled TMDL Determination and Implementation Planning: Alternative Approach to Water Quality Management with Optimization Techniques

Abstract Pollution reduction strategies based on approaches such as total maximum daily loads (TMDLS) are typically formulated as a load reduction quantification, followed by implementation planning, and an adaptive management approach. This formulation could restrict the exploration of many possible watershed management approaches using green infrastructure and best management practices. This is because pollutant load reductions are first fixed based on required water quality criteria, followed by finding solutions that may be able to achieve those reductions. This approach restricts the set of solutions to only those that will have to work at first pass, failing which the entire load-reduction calculation must be reworked. An enhanced approach is presented here that recasts the pollution reduction calculation as an optimization problem that factors in the implementation planning needed to achieve the proposed load reductions. This enhanced approach is shown to be more amenable to a holistic search through possible solutions, as well as with an increased potential for adaptive management or phased pollution reduction than the conventional approach.