The Orange-Senqu River is the third largest river basin in southern Africa. It is located within in the territories of Lesotho, South Africa, Botswana and Namibia. The Orange-Senqu drains in to the Atlantic Ocean at the border between South Africa and Namibia, where it forms a large estuarine delta. This estuarine delta (or estuary) represents a unique ecosystem on what is otherwise a wave exposed, hyper-arid coast with few freshwater inputs. The Orange-Senqu River estuary is recognised as an internationally important wetland for migratory birds and was accorded Ramsar Status in 1991 (Cowan 1995).