The medium-resolution bands on NASA's Moderate-Resolution Imaging Spectroradiometer (MODIS) were successfully used to detect and map the distribution of a harmful phytoplankton bloom in the Paracas Bay, Peru, that caused economic losses worth millions of dollars. Routine application of MODIS data can be a valuable and cost-effective way to monitor harmful blooms and other turbid water plumes that cause disruption to the fishery and aquaculture operations of many coastal areas.