A tool in the form of a habitat suitability index model (HSI) for the eastern oyster, Crassostrea virginica, was adapted to evaluate and compare the effects of alternative restoration plans in southwest Florida. A component of a large forecasting model, this tool simulates system response by examining the impact of freshwater inputs into the system. The eastern oyster is a good indicator species for modeling because of its sedentary nature and its susceptibility to natural and artificial changes. In addition, oysters form a complex three-dimensional reef structure, which provides habitat and food for numerous species of fish and invertebrates. The model focuses on salinity, temperature, depth, substrate, and high flow frequency as the particular requirements to determine habitat suitability for the eastern oyster. A geographic information system (GIS) incorporates the oyster HSI model, which includes larval and adult components, to determine responses spatially and temporally to facilitate the decision making process. This paper evaluates four hydrologic and land use scenarios for the C-43 West Basin Reservoir Project. Model results indicate that the Preferred Flow scenario and the future conditions with the Comprehensive Everglades Restoration Plan have higher HSI values then either the existing conditions or the future without the Comprehensive Everglades Plan.