Multi-objective decision-making methodologies are one among widely researched areas in recent years. As a result, many technologies have been developed. Among these, is Surrogate Worth Trade - Off (SWT). SWT has emerged in the areas of water resource planning and management, and is one of the multi-objective analysis methods described as an interactive method. This study includes reviewing and applying (SWT) method to optimally operate the Mosul Dam Reservoir. This operation policy sought to achieve two contradictory objectives: diverting water from the reservoir for irrigation purposes and releasing water from it for the purpose of hydropower generation. A comparison was also made of the results that were nominated from the application of this method, namely (allocating million cubic meters/ year for irrigation and generating 1572 GW-hour/year for power generation) with the results of the research  which four methods for solutions have been implemented. These are: weights, constraints, goal attainment, and step method. The results reveal that the used methods gave the optimal solution by (allocating 5906 million cubic meters/ year for irrigation and generating 1,600 GW-hour/year for power generation), (6236 ,1555) , (6188 ,1558) and (6121 , 1568) respectively. from the comparison It can be concluded that (SWT) is an efficient and promising method in identifying an operating policy for a single reservoir system with competing objectives.