The Sénégal River is a 1,790 km long river in West Africa, that forms the border between Senegal and Mauritania. It was called Bambotus by Pliny the Elder and Nias by Claudius Ptolemy. It was visited by Hanno the Carthaginian around 450 BC at his navigation from Carthage through the pillars of Herakles to Theon Ochema in the Gulf of Guinea. There was trade from here to the Mediterranean World, until the destruction of Carthage and its west African trade net in 146 BC.
The Sénégal is formed by the confluence of the Semefé and Bafing rivers at Bafoulabé. These rivers have their mutual source in Guinea; the Bafing River flows through Mali and the Semefé is on the Malian-Senegalese border. The Senegal is considered a sweet water river. From Bafoulabé the river flows west and then north through the spectacular Talari Gorges near Galougo and over the Gouina Falls, then flows more gently past Kayes and through semi-arid land along the northern border of Senegal to the Atlantic. Approaching its mouth, the Senegal passes through and the island on which the city of Saint-Louis, Senegal is located, then turns south. It is separated from the Atlantic Ocean by a thin strip of sand called the Langue de Barbarie before it pours into the ocean itself.
The river has two large dams along its course, the Manantali Dam in Mali, and the Maka-Diama dam on the Mauritania-Senegal border, near the outlet to the sea. The Manantali dam was built as a reservoir. The Maka-Diama dam prevents access of salt water into the inner country.
The Senegal River has a drainage basin of 483,181 km2 , a mean flow of 640 m3/s at its mouth, and an estimated annual discharge of 20,000 cubic hectometers. Important tributaries are the Faleme River, Karakoro River, and the Gorgol River.
In 1972 Mali, Mauritania and Senegal founded the Organisation pour la mise en valeur du fleuve Sénégal to manage the river basin. Guinea joined in 2005.