Juncal River in the context of Blanco River (Aconcagua)

The Aconcagua River is a river in Chile that rises from the conflux of two minor tributary rivers at 1,430 metres (4,690 ft) above sea level in the Andes, Juncal River from the east (which rise in the Nevado Juncal) and Blanco River from the south east. The Aconcagua river flows westward through the broad Aconcagua valley and enters the Pacific Ocean near the city of Concon, 20 kilometres (12 mi) north of Valparaíso.

The river has a course of about 142 kilometres (88 mi), and its waters irrigate the most populous sections of the Chilean provinces of San Felipe de Aconcagua and Los Andes, being the most important economic resource of those regions. During the course of the Aconcagua river, it receives contributions from many others rivers and swamps, reaching a mean flow of 39 cubic metres per second (1,400 cu ft/s).

The Río Blanco (Spanish for "white river") is a river of Chile. It originates close to Cerro Altar and flows generally northward for 15 km (9.3 mi) until it joins the Juncal River, at an elevation of approximately 1,430 m (4,690 ft), forming the Aconcagua River. The mouth of the river is located close to Chile Route 60.

Los Leones River is the main tributary of the river. The inferior course of the Río Blanco is adjacent to Río Blanco National Reserve.