Developing watershed protection strategies that implement numerous stormwater best management practices (BMPs) in large watersheds is a daunting task. Methods currently available for assessing the combined performance of multiple BMPs at the watershed scale are limited and cumbersome. Fortunately, the technology available within geographic information systems (GIS) can be used to efficiently assess the cumulative effects of multiple BMPs for an entire watershed. In this paper, I present an application of a GIS-based, watershed-scale approach to modeling numerous BMPs in a rapidly urbanizing watershed in north Georgia, where the methodology is being used as a tool for developing a stormwater management capital improvements program.