The watershed of Salar del Hombre Muerto has an area of , half of which is drained by the long Rio de Los Patos; this river enters into the salar from the northeast but originates on Galán and the Eastern Cordillera south of Hombre Muerto. Another tributary is the Rio Trapiche which comes into Hombre Muerto from the south and the Valle Hombre Muerto which lies between the two. The western side of Hombre Muerto on the other hand has only small springs. The Los Patos river has a discharge of and supplies a perennial lake, named Catal Lagoon, and during the rainy season large parts of the salt pan can flood. The discharge of Rio Trapiche is only about 1/9 of that of Rio de Los Patos. The Vega Trapiche and Vega Hombre Muerto wetlands are located on the southern margin of Hombre Muerto.