With the growth of population, shortage of water, and severe lack of water resources, optimization of reservoirs operation is a principal step in water resource planning and management. Therefore, in the present study, water was optimally allocated for a period from 2010 to 2020 using two simulationoptimization models based on Grey Wolf Optimization algorithm (GWO) and Genetic Algorithm (GA) and WEAP model. System operational indices including volumetric reliability, temporal reliability, vulnerability, and sustainability were used to evaluated the perforemance of optimization algorithms as well as WEAP model. The objective function of resources allocation problem was minimizing sum of the squared relative deficiencies for each month and maximizing reliability over the entire 11-year period. The results showed that optimal allocation solution found by the GWO algorithm with volumetric reliability, vulnerability, and sustainability indices which were 86.93, 0.29, and 21.48%, respectively was better and more suitable than the optimal allocation solution found by GA algorithm (which were 87.12, 0.41, and 21.34%, respectively). Finally, given an increase in the water demands , it is possible to obviate the needs of beneficiaries to an acceptable level and prevent severe draught in dry months through optimizing the use of available resources. According to the calculated indices for the WEAP model, in which volumetric reliability, vulnerability, and sustainability were equal to 87.46, 0.92, and 1.03%, respectively. It can be concluded that the use of optimization algorithm in optimal operation of the dam is more reliable than WEAP model.