Omo, river, c.500 mi (805 km) long, central and SW Ethiopia. Rising in the highlands south of Mt. Gorochan, some 40 mi (64 km) ENE of Nekemte, it flows generally south, receiving the Gojeb and Gibe rivers before emptying into Lake Turkana. The lower Omo valley, containing grasslands, volcanic outcrops, and riverine forests, is a Unesco World Heritage site. Ethiopia is constructing five dams on the Omo for hydroelectric power and commercial agricultural irrigation; the 797-ft (243-m) Gibe III hydroelectric dam, the third, is one of the largest dams in Africa. Its construction has led to relocation of local communities that have depended on the Omo's annual floods for livestock grazing and crop production, and to a drop in Lake Turkana's water level.

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