a river in southwestern Poland, a left tributary of the Oder (Odra) River. The Nysa Ktodzka is 195 km long and drains an area of 4,500 sq km. Rising in the Sudetes, the river flows through a hilly plain and, in its lower reaches, through the Silesian Lowlands. The average discharge at the river’s mouth is 25 cu m per sec, and the water level rises 3 or 4 m during flooding. In its upper reaches are the Otmuchowskie Reservoir and a hydroelectric power plant. The principal cities along the river are Nysa and Klodzko.