Bloom Event Prediction by Satellite Image Analysis Eutrophication and climate change menace our fresh waters. The result are harmful algae blooms which are menacing our drinking water reservoirs. We propose a bloom event prediction service by satellite images analysis supported by an innovative water quality data management system. Early warning systems are necessary in order to provide decision makers with the necessary tools to adapt, to communicate and to prevent events which can threaten safe drinking water supply to thousands of citizens. Our tool, developed with our partner Scalian and the support of the European Space Agency, the Center national d' tudes spatiales provides this service.