This book presents a report on a study conducted in a wastewater treatment plant at Hawassa University Referral Hospital. It aims at reviewing the design, configuration, effectiveness & quality of effluent discharged into lake Hawassa. The concern was to ensure full protection of lake hawassa. Hawassa City is one of the largest tourist attraction cities in Ethiopia where the lake is used as the heart of the the city's tourism industry in the form of recreation, fishing and many other public uses by villages located downstream. The study pointed out an overall acceptable treatment potential of the system for organic fraction of wastes, however its performance for heavy metals and nutrients was inadequate. The book also tries to link the potential problems to medicinal products, by-products and hormones which might have very serious effects to the lake ecosystem, though this part remains uninvestigated. In addition to this the treatment pond has been suffering from poor maintenance and follow up. The book therefore establishes the importance of proper followup and maintanance of stabilization ponds for them to function as potential treatment systems for developing countries