Originally known as the Pole River, the lower Birkenhead's valley is part of the Long Portage of the Douglas Road, also known as the Pemberton Portage. The height of land on this route has been variously called Pemberton Pass (officially), Birken Pass, Gates Pass, and (in gold rush times) Mosquito Pass. The river is a major salmon resource for the Lil'wat subgroup of the St'at'imc people, whose reserve community Mount Currie which spans the lowland between the very lowest reaches of the Lillooet and Birkenhead Rivers.