In Elassona Hydrological Basin, an area of 85 Km2 in Central Greece, two lignite deposits, Domeniko and Amourio, of 160x106 tn of lignite have been found. The exploitation process of the future open pit lignite mines is highly connected with the existence of surface and ground water in the area. The exploitation of these two lignite deposits will cause changes of the natural and human environment of the area. In this paper the hydrogeological conditions and the hydrodynamic status of surface and ground water of the basin are described. A water management system of the water coming from dewatering process is suggested.