The Segundo River (Spanish for second), also known as Xanaes, is a river in the center-north of the province of Córdoba, Argentina. It is born in the Paravachasca Valley at the confluence of the Los Molinos and Anizacate rivers, on the eastern slopes of the Cumbres de Achala (Sierras Grandes), about 2,000 m above mean sea level. It flows west–east and its course forms a reservoir at the Los Molinos Dam (at (31°49′S64°32′W), which is employed to generate hydroelectricity. It then flows to the northeast and divides into two main arms, which empty in the Mar Chiquita salt lake, 340 kilometres form its origin.