Lake Uluabat is valuable as a wetland with various ecological functions. Uluabat Lake, which has been considered as a fresh water source for the City of Bursa approximately 30 years ago and lost its water quality characteristics in time, is now under several serious environmental risks. The present situation of the lake can not provide the essential protection to sustain the biodiversity at the lake. It has been previously found that the land that the lake covers has been reduced by approximately 12% in 14 years, with the effect of the drainage waters from agricultural lands and industry, and the sediment load from the rivers around. Uluabat residents who used to maintain life by hunting fish is having economical problems because of the decrease in fish potential and this problem is associated with the lake's water pollution. Because of its ecological importance, Uluabat Lake has been designated as one of the 9 Ramsar sites in Turkey by Turkish Ministry of Environment, in 1998. This global protection status necessitated the development of an environmental management plan for Lake Uluabat. As apart of this effort, the Ecological Risk Assessment-Problem Formulation study that is presented in this paper was conducted. Ecological Risk Assessment (ERA) is applied in various fields, especially in the developed countries. ERA is defined as a process needed to collect, organize, and present scientific information to develop environmental management decisions. United States Environmental Protection Agency (EPA) organizes the ERA in 3 main stages: 1. Problem formulation, 2.Analysis, 3.Risk identification: The methodology proposed by the EPA was applied and the first main stage, Problem Formulation was conducted in this study. In the concept of the problem formulation, the adverse conditions that the site had been exposed to, and the risks that had arisen were determined. The problem formulation studies were first initiated with the management objectives that had been determined during the workshops with the interested groups (the experts working on the lake, representatives from the related public enterprises, the residents, representatives from related nongovernmental organizations, etc.). The two management objectives determined were; 1. To promote the biodiversity at Uluabat Lake Ramsar site, 2. To improve the physical and chemical quality of the water of the lake. At the second step of the problem formulation, the stressors of the ecosystem were identified by using the information from site visits, existent information, and views of the experts working on the lake. Stressors are defined as the physical, chemical, or biological components that may cause the ecosystem to react adversely. The stressors defined for Lake Uluabat can be considered at. an expression of the anthropogenic factors that could affect the Uluabat Lake ecosystem. The stressors were identified as: 1. Suspended matters, 2.Chemical substances, 3.Nutrients, and 4.Hunting. As the third step, 8 assessment endpoints were determined to represent the water quality, aqueous life, and other ecological functions of the Lake Uluabat. The assessment endpoints are: I.Lily beds, 2. Water quality, 3.Dynamic water level, 4. Fish diversity, 5.Habitats at delta, 6.Flora diversity, 7.Bird diversity, 8.Trophic level of the lake. Assessment end-points are the ecological entities that worth protection. At the fourth stage, a conceptual model displaying the relationship between the stressors ana assessment endpoints was developed. As the final step, all the information including the management objectives, stressors, assessment endpoints, ana conceptual model were used to make a prioritization among the stressors to focus on. A fuzzy-based approach was used as the method for prioritization. The ERA-problem formulation study conducted for Lake Uluabat presented the problem thoroughly, and suggested a background for the subsequent action planning. According to the results of this study, Lake Uluabat is under various risks that could be prioritized. The conceptual model, one of the products of conceptual model, facilitated the communication among the interested groups. The fuzzy based prioritization method provided the essential methodology to scientifically integrate expert views into the risk assessment process. Adoption of a similar approach in the environmental management of sites with special protection status, would provide the risk managers and interested groups consider the problem with equal and sufficient information. Ecological risk assessment provides a scientific backgrouna while selecting the most appropriate management choice. However, the tool would show its concrete benefits when the environmental management decisions are applied.