The reservoir operation is a challenging task for achieving the design performance of any reservoir. Though many reservoir operation modeling techniques are available, still the reservoir managers are adopting the conventional procedures. Hyderabad water supply system is a complex system and having multiple sources of reservoirs to supply drinking water to cater Hyderabad city and among one of them is Himayathsagar reservoir. In this paper, an attempt was made to evolve the reservoir operation strategy by developing models based on crisp concepts and fuzzy logic concepts. The initial simulation was made to understand historical storages and release curves using the inflows and evaporation from observed data. A model has been developed based on crisp concepts and later to evolve a release policy using fuzzy logic concepts. The model results were obtained. Comparisons of historic, crisp and fuzzy results were presented to demonstrate the improvement, relevance, and applicability of the developed methodology.