LOWER ST. JOHNS RIVER TOTAL MAXIMUM DAILY LOAD COMPLIANCE USING OPTIMIZATION ANALYSIS OF POINT AND NON-POINT SOURCE LOADS

St. Johns River Water Management District (SJRWMD) has been participating and assisting affected parties in addressing water quality issues in the Lower St. Johns River (LSJR) basin. The ultimate goal is to improve the water quality throughout the District. One of many water quality improvement approaches has been the establishment of Total Maximum Daily Load (TMDL) limits for municipalities, special districts, and industries regulated under the National Pollutant Discharge Elimination System (NPDES).The first phase of SJRWMD's compliance strategy involved identifying a broad range of projects that could be cost-effectively implemented by major domestic point sources in the LSJR basin, while maximizing reuse or artificial recharge of reclaimed water to achieve multiple resource conservation and utilization goals. An optimization model was developed as a planninglevel tool to identify such projects. These projects comprise three categories: (1) projects that would meet the TMDL reduction limits, (2) projects that would significantly exceed the TMDL reduction limits, and (3) projects that would maximize reuse to achieve near zero discharge to the LSJR from these sources. This paper presents the process for selecting the projects and the application of the optimization model to develop projects that would achieve TMDL compliance while minimizing costs for wastewater infrastructure development.