Diagnostic analysis of wetlands is an ordered/structured method of examining wetland systems to identify their values and constraints for the solution of the environmental problems. This study focuses on the diagnostic analysis of Lake Uluabat on the feasibility of "Objective Oriented Project Planning (OOPP)" approach, created by the United States Agency for International Development (USAID) and further improved by the Deutsche Geselischaft fur Technische Zusammenarbeit (GTZ). Negative changes both in water quality and quantity were determined as the core problems. The main results were summanzed as the water pollution and fluctuation in the water level caused by the urban and agricultural waste disposals, sedimentation, and overfishing. These negative effects cause loss of biodiversity and damage to crops. Disposal control, training, adequate regulations, and a centralized control and monitoring authority have been proposed to cope with the determined problems.