The Imo River (Igbo: Imo Mmiri) is in southeastern Nigeria and flows into the Atlantic Ocean. Its estuary is around wide, and the river has an annual discharge of with 26,000 hectares of wetland. The Imo's tributary Rivers are the Otamiri and Oramirukwa. The Imo was cleared under the British colonial administration of Nigeria in 1907–1908 and 1911; first to Aba and then to Udo near Umuahia.