The current study aims at assessing the risks of Roodbar Dam using Multi Attribute Decision Making and RAM-D Model. First, a list of environmental risks was provided and placed at disposal of experts who are aware in the fields of dam and environment. Consequently, 33 risk factors were identified. The results of the questionnaire were analyzed and prioritized using TOPSIS Method. Based on the noted method, three risks including impact on landscape and tourism, waste disposal and impact on habitats which obtained the scores equal to 0.739, 0.667 and 0.66 respectively were considered the most important risks. Afterwards, by means of AHP Method and Expert choice Software, the risks were assessed and analyzed in the form of 6 risk groups based on the intensity and probability of occurrence. At the next step, considering the varied results between the methods; TOPSIS and AHP, the results were unified using the integrated methods. Finally, 10 risks were determined for Roodbar Dam in construction phase. Then, by means of RAM-D the risks were assessed. Based on the results of the method, land use change, impact on habitats and influence on aquatics with the scores of 9, 6.75 and 4.5 were determined the most signification risks of Roodbar Dam in construction phase. The risks are consequences of the destruction of the forest cover of oak species, the change of the main land use in the area and the activities of the construction phase of dam on Roodbar River. At the end, to mitigate the obtained risks, managerial and corrective measures were recommended.