This invention relates to a system and method for optimum watershed outflow retention, control and management through the utilization of structural best management practices (SBMP) such as constructed ponds to achieve the objects of controlling flood and or maintaining base flow. it is a method for investigating, identifying, implementing and operating SBMP for mitigating, controlling and managing the impacts of land development on watershed outflow quantity. It is a novel and cost effective decision support system (DSS) for current and future mitigation of the effects of land use changes on river discharge. It compiles tools and techniques that include remote sensing (RS) and hydrological modeling to provide a meaningful, integrated and multi-criteria solution. Maps identifying the locations and sizes of SBMP will help planners and decision makers to take the impacts of climate change into account. The future SBMP detailed plans will be generated in advance to help planners and decision makers avoid the negative impacts of land use changes on stream flow magnitude in the watershed.