Harmful Algal Blooms (HABs) in the Great Lakes are becoming increasingly problematic as these events are happening more often, in more areas, and lasting longer. Satellite remote sensing can be effectively used to map and monitor HAB events in the Great Lakes to help resource managers and decision makers address the problem. A satellite based HAB mapping algorithm has been developed and tested in the Western basin of Lake Erie where severe HAB events have regularly occurred. The algorithm has been developed from in situ spectral reflectance measurements and coincident concentration samples and has been applied to both MODIS and MERIS satellite imagery. The algorithm also utilizes ancillary data to help differentiate harmful from non- harmful algal blooms that can occur simultaneously. Also examined is the utility of hyperspectral (HICO) satellite imagery from the Space Station for mapping HABs and a comparison to ship based hyperspectral radiometric measurements was made. Extent and duration were derived for a time series of satellite images during the 2011 summer HAB event in Lake Erie. Also presented is a comparison of Cyanobacteria shipborne in situ spectral profiles and measured concentrations collected during the Lake Erie summer field season