The Baro River (Amharic: ባሮ ወንዝ Baro/Openo Wenz, known to the Anuak as Openo River) is a river in southwestern Ethiopia, which defines part of Ethiopia's border with South Sudan. From its source in the Ethiopian Highlands it flows west for 306 kilometres (190 mi) to join the Pibor River. The Baro-Pibor confluence marks the beginning of the Sobat River, a tributary of the White Nile. The Baro and its tributaries drain a watershed 41,400 km2 (16,000 sq mi) in size. The river's mean annual discharge at its mouth is 241 m³/s (8,510 ft³/s).