This research analyzed the efficiency of the BMP Siting Tool developed by the US Environmental Protection Agency and the Grey-to-Green Decision Support Tool. Both tools were used in conjunction with ArcGIS 10.1 to obtain cartographic data illustrating suitable sites for bioswales and infiltration basins in Hillsborough County, Florida. The data were integrated with the Karst Aquifer Vulnerability Index (KAVI) groundwater vulnerability model. The BMP Siting Tool sited 2.80% of all bioswales and 27.89% of all infiltration basins above vulnerable areas identified by the KAVI. Alternatively, 21.66% of all bioswales and 9.62% of all infiltration basins sited by the Grey-to-Green Decision Support Tool were above vulnerable areas. The results of this analysis prompted the proposal of a supplemental framework unique to each tool’s weakness. The idea behind the supplemental framework is to determine the most suitable sites for stormwater BMPs by refining the current siting framework to better respect groundwater integrity.