In this work we present the model of a hydroelectric power plant in the framework of Mixed Logic Dynamical (MLD) systems. Each outflow unit exhibits a hybrid behaviour since flaps, gates and turbines are controlled with logical inputs and the outflow dynamics depend on the logical state of the unit. We show how to derive detailed models of each unit considering not only standard operating conditions, but also emergencies and startup and shut-down procedures. The control task can be formulated with a model predictive control scheme.