Forecasting marine spill risk along the U.S. Pacific coasts

This study analyzes historical trends and forecasts of spill risks in coastal counties along the U.S. Pacific, including Alaska and Hawaii. The method calculates spill impact, which rises with size but diminishes with age and distance from the coast. Over the past two decades, spill risks in California and Washington have increased significantly. Coastal counties in Puget Sound and San Francisco Bay have seen the highest increases, surpassing 2000 levels by 79 % and 39 %, respectively. Alaska experienced a moderate rise, while Oregon and Hawaii had smaller but noteworthy increases. Ocean currents may reduce risk by 38 % on average. Most counties are expected to experience increasing spill risks, particularly in Southern California and Southwest Washington, which could see nearly a 50 % increase by 2033 compared to present levels. These findings can help coastal zone monitoring and inform policies for protecting coastal regions, regulating marine transportation and reducing spill vulnerability.