The main course of the river is short, formed in the Willamette Valley by the confluence of the North and South Santiam rivers on the border between Linn and Marion counties approximately 8 miles (13 km) northeast of Albany.

It flows generally west-northwest in a slow meandering course to join the Willamette from the east approximately 8 miles (13 km) north of Albany.

Both the North and South Santiam rise in high Cascades in eastern Linn County.

After days of arguing, Alaquema told Gain, "We understand fully what you mean and that it may be better for us, but our minds are made up."

Additionally the Willamette National Forest has fire crews on the Mckenzie and Middle Fork Ranger Districts.