Harmful algal blooms (HABs) have become endemic to the western basin of Lake Erie. When HABs occur they impact multiple ecosystem services, especially in the western Lake Erie coastal communities. The goals of this work are to characterize the spatio-temporal variability in harmful algal blooms, to investigate the biophysical factors leading to bloom and surface scum formation, and to probabilistically predict the location, intensity, and duration of blooms under different future scenarios. Bloom forecasts will be driven by various future climate, watershed nutrient loading, and invasive mussel scenarios. Results will be provided in a format suitable for assessing ecosystem services impacts, and will include the probability of the bloom reaching critical levels within various nearshore and offshore areas of western Lake Erie, under various scenarios.