<p>A method and device of controlling at least one water level at a predetermined point influenced by at least one hydroelectric power plant (P) is disclosed, wherein the discharge through the power plant is regulated. The method employs a model predictive control (MPC) algorithm. In a preferred embodiment, a cascade of power plants is controlled simultaneously. The method is specifically adapted for handling large amounts of discharge and the specific constraints in connection with the hydraulics of hydroelectric power plants and avoids large discharge variations.</p>
