The Meta River is formed in the Meta Department, Colombia by the confluence of the Humea, Guatiquía and Guayuriba rivers. It flows east-northeastward across the Llanos Orientales plains of Colombia through an ancient fault. The Meta river is 804 km long and its drainage basin is 93,800 km². The Meta divides the Colombian llanos in two different realms: the western portion on the left is more humid, receives the relatively nutrient-rich sediments from the Andean mountain range and therefore soils and tributaries are also nutrient-rich, while the eastern portion, high plain or altillanura, drains not to the Meta river but to the Orinoco, has a longer dry season and soils and surface waters are oligotrophic (nutrient poor).The major tributaries of the Meta are the Cravo Sur, the Casanare, the Cusiana, the Upía and the Manacacías.