RESPEC recently was awarded a contract with the City of Sioux Falls to develop a watershed master plan for the Central Big Sioux River.  A major challenge faced by decision makers within the Central Big Sioux River Watershed (CBSRW) is how to select the best combination of practices to implement among the many options available that will result in the most cost-effective, achievable, and practical management strategy possible.   A watershed-scale, decision-support framework that is based on cost optimization is being developed to support government and local watershed planning agencies as they coordinate watershed-scale investments to achieve needed improvements in water quality.  This decision-support framework will assist in developing the Total Maximum Daily Load (TMDL) implementation plan, identifying management practices to achieve pollutant reductions under a municipal separate storm sewer system (MS4) stormwater permit, and developing a phased Best Management Plan ( BMP) installation plan that is optimized for both cost- and water-quality effectiveness.