Lake Hawassa is a freshwater lake in Ethiopia's Sidama Region, lying west of Hawassa city within the Awasa Caldera of the Ethiopian Rift Valley . The lake has a surface area of approximately 8,500-9,000 hectares, a maximum depth of 18-22 meters, and shoreline length varying between 50-65 kilometers . It is the most studied of Ethiopia's Rift Valley lakes due to its accessibility . The lake supports abundant phytoplankton with over 100 identified species, extensive beds of Cyperaceae and Typha vegetation, and floating plants including the world's smallest flowering plant, Wolffia arrhiza . Recent studies indicate the lake is experiencing eutrophication and depth reduction from sediment inflow.