Bío Bío River

The Biobío River (also known as Bío Bío or Bio-Bio) is the second largest river in Chile. It originates from Icalma and Galletué lakes in the Andes and flows 380 km to the Gulf of Arauco on the Pacific Ocean.

The major tributaries of the river are the Malleco and the Laja. The river is Chile's second-longest river (the longest being Loa River) and Biobío basin is Chile's third largest watershed, after Loa and Baker basins. The river is also the widest river in Chile, with an average width of 1 km. In the Metropolitan area of Concepción, the river is crossed by four bridges: Biobío Railroad Bridge (1889), Biobío Bridge (1942), Juan Pablo II Bridge (1973) and Llacolén Bridge (2000).

Course

The Biobío river originates at the east shore of Galletué Lake. The river flows east for a few kilometers to the point where it receives the waters of the near Icalma Lake, through a short stream. Then, it turns its course northwestward, meandering through a broad Andean valley and receiving the discharges from some minor tributaries, as are the Lonquimay and the Rahue. The Lonquimay is fed by some glaciers of Sierra Nevada and passes close to the town of the same name. Just downstream from the confluence with the Rahue, the upper course of the river, locally known as Alto Bío Bío, begins to run rapidly through a narrow valley surrounded by mountains with slopes more and more abrupt as the river run to lower elevations. Then the river, along the lower course of its tributaries in this area, is impounded by Ralco Dam. Below the dam, the river skirts a southwestern spur of Callaqui volcano before falling into Pangue Reservoir.