This study provides a comprehensive examination of the use of trajectory modeling to estimate financial impacts of oil spills, including natural resource damages, response costs, and socioeconomic costs, as well as an opportunity to examine how spill size, oil type, response strategy, and probabilistic trajectory factors impact costs. The inclusion of NRDA, response, and socioeconomic costs in the modeling allows for an assessment of the relative proportion of NRDA costs to response and socioeconomic costs to further support the findings of past studies that refute the myth that NRDA costs are the overriding factors in most spill cases. The study demonstrates the overall financial and NRDA benefits of dispersant use. Estimated total bio-economic costs for oil spill scenarios involving four oil types and three spill sizes for two locations in San Francisco Bay, were modeled. Assuming present-day mechanical-only response, total costs range from $30 to $520 million. Estimated total bioeconomic costs would be reduced to $11 to $113 million if dispersants were used with high effectiveness. Dispersant use would reduce response costs, and if used effectively, could reduce NRDA and socioeconomic damages substantially, as both of these costs are driven by the amount of surface and shoreline oiling.

Oil spill response may include use of chemical dispersants and in situ burning equipment, in addition to traditional mechanical response equipment. To evaluate the potential impacts of various response strategies, oil spill and atmospheric plume modeling were performed to evaluate areas of the atmosphere at sea level, water areas, shoreline lengths, sediment areas, and water volumes impacted above thresholds of concern to biological species and habitats, human health and socioeconomic resources. For the oil spill modeling, a stochastic approach was used to allow the range and frequency of possible environmental conditions to be examined for each spill site, spill volume and response option evaluated. Long term (decade or more) wind and current records were sampled at random and model runs were performed for each of the spill dates-times selected. This provides a statistical description of the environmental fate and impacts that would result if a spill occurred. Stochastic modeling was performed in five representative locations in the US: (1) offshore of Delaware Bay, (2) offshore of Galveston Bay, (3) offshore of San Francisco Bay, (4) Prince William Sound, and (5) offshore of the Florida Keys. These data were used to evaluate potential impacts of changes in response strategies, i.e., combining use of dispersants and in situ burning with traditional mechanical recovery. The results of the oil spill modeling for the Florida Straits location are summarized herein.