A numerical model has been developed to rigorously simulate the physical oceanographic effects of one or several 100 megawatt Ocean Thermal Energy Conversion (OTEC) plant(s). The model suggests that OTEC plants can be configured such that the plant can conduct continuous operations, with resulting temperature and nutrient perturbations that are within naturally occurring levels. This presentation will describe the development and results of the numerical model, focusing on the physical and biological effects of operating single and multiple 100 megawatt OTEC plants in Hawaiian waters, and will discuss the implications of these results towards future design and regulatory work. Detailed statistics and visualization of the thermal variation, plume dilution, and estimates of the biological growth around an OTEC plant will be presented. Studies to date suggest that by discharging the OTEC flows downwards at a depth below 70 meters, the dilution is adequate and nutrient enrichment is small enough so that 100 megawatt OTEC plants could be operated in a sustainable manner on a continuous basis.