<p>Due to the global water shortage and effects of climate change, more advanced techniques have been developed to ensure efficient reservoir operation. Using the Many-objective Particle Swarm Optimization algorithm, this research investigates the complex management of high-dimensional conflicting objectives within the Azad Dam. By utilizing the current simulation-optimization model, an effort is made to optimize the downstream water supply and its reliability while minimizing violations of safe downstream discharge thresholds. The performance of the proposed policy is significantly better when compared to the current operational baseline over a seven-year period. A 42.8% increase in water supply volume and a 7.9% improvement in reliability were achieved through the most effective strategy. In addition, flood damage risks decreased by 57.2%. Hydropower generation saw a slight decrease of 4.39% as necessary trade-offs were made to maintain flood control volumes. These results support the notion that the algorithm can provide robust policies for managing water resources sustainably.</p> Graphical Abstract <p></p>