The Lillooet River is a major river of the southern Coast Mountains of British Columbia. It begins at Silt Lake, on the southern edge of the Lillooet Crown Icecap about 80 kilometres northwest of Pemberton and about 85 kilometres northwest of Whistler. Its upper length is about 95 kilometres in length, entering Lillooet Lake about 15 km downstream from Pemberton on the eastern outskirts of the Mount Currie reserve of the Lil'wat branch of the St'at'imc people.
Below the 30 km length of Lillooet Lake, it resumes again just north of the native community at Skatin, or Skookumchuck Hot Springs. The lower stretch of the Lillooet River, from Lillooet Lake to Harrison Lake, is approximately 55 km (c. 34 mi) in length. Its main tributaries are the Meager Creek, the Ryan River, the Green River, and the Birkenhead River. Below Harrison Lake, the stream is renamed as the Harrison River, which enters the Fraser near the native community of Chehalis. The lower Lillooet River and Lillooet Lake were part of a briefly-lived main route between the Coast and the Interior in the days of the Fraser Canyon Gold Rush. See the Douglas Road.
Eruption of Mount Meager, 2350 BP
The Lillooet River was dammed with breccia from a Plinian style eruption that was erupted from Mount Meager 2350 BP. The breccia damming the Lillooet River was not very strong, then the water soon eroded the breccia that was damming the river, forming Keyhole Falls. There was a massive flood when the water first broke through the breccia. The flood was big enough that small house sized blocks of breccia were carried away during the flood.
