Tampa Bay Water initiated water supply planning to provide for the requirements of their governing Master Water Plan and to meet projected demands for a 20-year planning horizon. Diminishing water sources combined with evolving state and federal water policies render this effort exceptionally difficult. With this in mind, even preliminary project feasibility studies need to encompass a comprehensive evaluation of issues affecting the permitting, development, and operation of the water source in conjunction with impacts on regional environmental conditions. Black & Veatch developed planning-level feasibility studies for nearly 40 potential new water sources that included vulnerability assessments paralleling Florida's Source Water Assessment Program requirements to delineate the water source boundaries, inventory contaminants of concern, and present a determination of potential vulnerability to contamination. The vulnerability assessments were primarily developed using the data available in the Environmental Protection Agency's Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) program. These data provided a foundation for evaluating interrelated issues such as topography, land use, and regulated pollution sources. Consideration of these planning-level assessments provided a classification of the water source's potential vulnerability to contamination and added an important component to the feasibility studies. These studies will assist Tampa Bay Water with future water supply planning decisions.