Abstract Macroscale hydrological and land surface models increasingly rely on novel streamflow routing algorithms that explicitly account for the presence of engineered water storages, which largely affect river basin dynamics. In this short communication, we contribute to this growing field by presenting VIC-ResOpt, a software package for the representation and optimization of water reservoirs in the routing model commonly used as a post-processor with the Variable Infiltration Capacity (VIC) hydrologic model. VIC-ResOpt comprises tools for simulating different reservoir operating approaches, optimizing operations, and exploring the sensitivity of the model output with respect to the parameterization of the operating rules. The package relies on automated scripts and optimization engines, thereby requiring minimal user effort. We demonstrate some of its functionalities in the upper portion of the Chao Phraya river basin (Thailand), which is regulated by two large dams.