This paper deals with Optimization via Simulation (OvS) of the management of a catchment basin involving dams, electrical power station, pumping station, valves, etc. We explain how an iterative process allows us to integrate optimization algorithms into a discrete-event simulation using a DOvS (Discrete Optimization via Simulation) methodology. This process has been implemented using the DEVSimPy (DEVS simulator in Python language) environment and the obtained results point out the feasibility of the proposed approach. Furthermore this software is actually used by the Corsican Water Agency in order to efficiently manage the South East water network.