The Omo River is an important river of southern Ethiopia. Its course is entirely contained within the boundaries of Ethiopia, and empties into Lake Turkana on the border with Kenya. It is the principal stream of an endorheic drainage basin ; the part that the Omo drains includes part of the western Oromia Region and the middle of the Southern Nations, Nationalities and People’s Region.
This river rises in the highlands and is a perennial river. Its course is generally to the south, however with a major bend to the west at about 7° N 37° 30′ E to about 36° E where it turns south until 5° 30′ N where it makes a large S- bend then resumes its southerly course to Lake Turkana. According to materials published by the Ethiopian Central Statistical Agency , the Omo River is 760 kilometer long.
In its course the Omo has a total fall of about 6000 ft (2,000 m), from an elevation of 7600 ft at its source to 1600 ft at lake-level, and is consequently a very rapid stream, being broken by the Kokobi and other falls, and navigable only for a short distance above where it empties into Lake Turkana, one of the lakes of the East African Rift. The Spectrum Guide to Ethiopia describes it as a popular site for white water rafting in September and October, when the river is still high from the rainy season. Its most important tributary is the Gibe River; smaller tributaries include the Wabi, Denchya, Gojeb, Muiand Usno rivers.
The Omo River formed the eastern boundaries for the former kingdoms of Janjero, and Garo. The Omo also flows past the Mago and Omo National Parks, which are known for their wildlife. Many animals live near and on the river, including hippopotamuses, crocodiles, and Bitis.
The lower valley of the Omo is currently believed by some to have been a crossroads for thousands of years as various cultures and ethnic groups migrated around the region. To this day, the people of the Lower Valley of the Omo, including the Mursi, Suri, Nyangatom, Dizi and Me’en, are studied for their diversity.
The entire Omo river basin is also important geologically and archaeologically. Several hominid fossils and archaeological localities, dating to the Pliocene and Pleistocene, have been excavated by French and American teams. Fossils belonging to the genera Australopithecine and Homo have been found at several archaeological sites, as well as tools made from quartzite, the oldest of which date back to about 2.4 million years ago. Because of this, the site was designated a UNESCO World Heritage Site in 1980.
When they were discovered it was thought that the tools may have been part of a so-called pre-Oldowan industry, even more primitive than what was found in the Olduvai Gorge. Later research has shown that the crude looks of the tools were in fact caused by very poor raw materials, and that the techniques used and the shapes permit their inclusion in the Olodwan.