Countries of occurrence include: Angola, Benin, Cameroon, Chad, Congo, The Democratic Republic of the Congo, Côte d'Ivoire, Equatorial Guinea, Gabon, The Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone and Togo. T. senegalensis occurs in most of the coastal marine waters, brackish estuaries, and adjacent rivers along the coast of West Africa from southern Mauritania (16°N) to the Loge, Dande, Bengo and Cuanza Rivers, Angola (18°S) (Beal 1939, Allen 1942, Blancou 1960, Robinson 1971, Husar 1978, Nishiwaki 1984, Grigione 1996, Powell 1996, Perrin 2001). They ascend most major rivers within their range until cataracts or shallow water prevents their progress. In some rivers, such as along the Benue River, manatees seek refuge during the dry season in permanent lakes that communicate with the rivers during high water but are cutoff when river waters subside (Sykes 1974). Manatees can be found 75 km offshore among the shallow coastal flats and mangrove creeks (with abundant seagrasses and calm water) of the Bijagos Archipelago of Guinea-Bissau (Powell 1990) as well as Casamance (Senegal). Isolated populations cutoff from the sea are found in Lake Volta, Ghana above the Volta hydroelectric dam. An additional population, essentially landlocked above the major rapids, is found in the upper reaches of Niger River in the inland delta of Mali as far as Segou, which are the furthest inland records, over 2,000 km from the ocean (Hatt 1934, Kienta 1982). Manatees are landlocked in the Logone and Chari Rivers of Chad (Hatt 1934, Salkind 1996). They occur along the entire length of the Gambia River, penetrating into Senegal where there are records as far upstream as Niokola Koba National Park (Grubb et al. 1998). In Chad, manatees are present in Lake Léré and Lake de Tréné along the Mayo-Kebbi, Bahr Keeta and Baningi rivers; manatees are also reported from the Baningi, Logone and Chari Rivers tributaries of Lake Chad. Sightings of manatees have been reported from Lake Chad but there are no documented records (Ita 1994). Centers of population appear to be Guinea-Bissau; the lagoons of Ivory Coast; the lower reaches of the Niger River, Nigeria; Sanaga River, Cameroon; coastal lagoons of Gabon and the lower reaches of the Congo River (Powell 1996). The manatee population in West Africa is reported to be reduced, but their present range appears to be comparable to historic reports (Husar 1978).

MAJOR LAKES: Volta, Inland delta Mali, Lake Léré, Lake de Tréné.

MAJOR RIVERS: (N to S) includes lakes within these river systems, the Senegal, Saloum, Gambia, Casamance, Cahacheu, Rio Mansoa, Rio Geba, Rio Grande de Bulba, Rio Tombali, Rio Cacine, Kogon, Kondoure, Sierra Leone, Great Scarcies, Little Scarcies, Sherbro, Malem, Waanje, Sewa, Missunado, Cavally, St. Paul, Morro, St. John, Bandama, Niouniourou, Sassandra, Comoe, Bia, Tano, Volta, Mono, Oueme, Niger, Mekrou, Benue, Cross, Pie, Katsena Ala, Deb, Okigb, Issa, Bani, Akwayafe, Rio del Rey, Ngosso, Andokat, Mene, Munaya, Wouri, Sanaga, Faro, Chari, Bamaingui, Bahr-Kieta, Logoné, Mitémélé, Gabon, Ogoué, Lovanzi, Kouliou, Congo, Loge, Dande, Bengo, and Cuanza.