The North Santiam River is a 92-mile (148 km) tributary of the Santiam River in western Oregon in the United States. It drains 766 square miles (1,980 km2) of the Cascade Range on the eastern side of the Willamette Valley east of Salem. It is impounded by Detroit Dam in the mountains west of Detroit to form Detroit Lake for flood control. Detroit Lake State Park is along the northern shore of the lake.