Value of the Data •Data on the volumes of reservoir inflow, reservoir storage, evaporation from the reservoir, precipitation in the reservoir and release from the reservoir in the Karun-4 reservoir provide an overview of the operation of the reservoir between the years of 2010 and 2019. •These data can be used to analyze the water resources status and energy generation in the Karun-4 hydropower reservoirs operation. •The data will be useful for modeling purposes, especially relating to the Karun-4 reservoir operation. •They can also be used to examine the impact of Karun-4 reservoir operation on generating energy. •The analysis obtained herein with Evolutionary Algorithms (EAs) solver can serve as a standard benchmark for other researchers to compare their analysis of the other methods using this dataset. •Other researchers can use the MSA algorithm in solving large-scale problems such as the hydropower reservoir operation with confidently.