Pilcomayo

Pilcomayo river is the longest western tributary of the Paraguay river, with a length of 1,100 kilometers. It has a drainage basin with a surface size of 270,000 square kilometers and a mean discharge of 200 cubic meters per second. The Pilcomayo silts up along its path and separates into two main branches, North and South. These branches come together after a while to form the Lower Pilcomayo.

The Pilcomayo is located in Bolivia's Oruro Department, east of Lake Poopó, in the foothills of the Andes mountain range. The Pilcomayo is thought to have originated in the Jach'a Juqhu River. The Jach'a Juqhu River is given the titles Aguas Calientes and Kachi Mayu as it flows upstream. The river is known as Pilcomayo after its confluence with the Chillawa. From there, it runs southeast through the departments of Chuquisaca and Tarija, through the Argentine province of Formosa and the Paraguayan Gran Chaco plains, forming the majority of the border between the two nations before joining the Paraguay River near Asunción. On the Argentine side of the border is the Ro Pilcomayo National Park. It also forms a short section of the Argentina–Bolivia–Paraguay border, just before the Argentina–Bolivia–Paraguay tripoint.

Length: 684 miles (shared with Bolivia and Paraguay)