Developing management strategies to minimize algal blooms requires detailed knowledge about the landscape factors that drive them. We will use over 35 years of Landsat imagery to map nearshore algal bloom intensity and extent at unprecedented spatial and temporal resolution. These will be related to watershed nutrient and sediment exports predicted using advanced watershed models at both sub-basin and Great Lakes Basin scales. We will then establish nutrient thresholds for specific HAB risks, identify sources of nutrients on the landscape, and prioritize restoration strategies.