After flowing for 115 km (71 mi) in this portion of its course and having run through the city of Calama, the Loa receives the waters of San Salvador River at the locality of Chacance.

From Quillagua, its dry channel turns westward again and marks the border between the regions of Tarapacá and Antofagasta.

Along its lower course, the Loa flows through a 500-metre-deep (1,600 ft) canyon, which crosses the Chilean Coastal Range.

The increase of its water volume occurs mainly in January and February, as a consequence of the phenomenon known locally as Bolivian Winter.

It is no longer used by the Ferrocarril de Antofagasta a Bolivia, however it still holds the notability of being, at 104 m (341 ft), one of the highest bridges in Chile.