The Birkenhead River, formerly known as the Portage River, the Pole River and the Mosquito River, is a major tributary of the Lillooet River, which via Harrison Lake and the Harrison River is one of the major tributaries of the lower Fraser River. It is just over 50 km long from its upper reaches in the unnamed ranges south of Bralorne, British Columbia (these ranges are sometimes called the Noel Ranges or the Birkenhead Ranges); their western area towards the named Bendor Range east of Bralorne is sometimes called the Cadwallader Ranges.