Clanwilliam is a town in the Olifants River valley in the Western Cape, South Africa, about 200 kilometres (120 mi) north of Cape Town. It is located in, and the seat of, the Cederberg Local Municipality. As of 2011 Clanwilliam had a population of 7,674.Clanwilliam is situated at an elevation of 100 metres (330 ft), between the western slopes of the Cederberg mountains and the east bank of the Olifants River, which is impounded there by the Clanwilliam Dam.