It rises in the Central Oregon Coast Range in western Lane County, approximately 10 mi (16 km) west of Veneta. It flows east through the mountains to Veneta, through the Fern Ridge Reservoir, and then north into the Willamette Valley, roughly parallel to and west of the Willamette River. It joins the Willamette from the southwest approximately 4 mi (6.5 km) west of Halsey. The Fern Ridge Reservoir was created in 1942 when the United States Army Corps of Engineers dammed the river to control flooding.