At Riolunato a dam across the Scoltenna river (which flows down from the mountains of the Regional Park, and later combines with the Leo to form the Panaro) creates the reservoir which, kilometres downstream, supplies the Strettara hydroelectric plant. It is fascinating to trace the path of the long enclosed channel which conveys the water along the side of a valley so narrow that it seems to have been cut into the rock, and over aqueducts, to the point where it starts its fall to the Strettara turbines. A bridge near to the hydroelectric plant is one of the oldest in the Frignano area, and used to be guarded by four stone lions until they were removed when work started on construction of the nearby tunnel for the new Estense road.