The Ontonagon River is a river flowing into Lake Superior at the village of Ontonagon, on the western Upper Peninsula of Michigan in the United States. The main stem of the river is 25 mi long and is formed by a confluence of several longer branches, portions of which have been collectively designated as a National Wild and Scenic River. Several waterfalls occur on the river including Agate Falls and Bond Falls.

Course

The Ontonagon River's principal tributaries are its West, South, Middle and East branches, all of which flow in part through the Ottawa National Forest: Below the confluence of its various branches, the Ontonagon River flows generally north-northwestwardly for 39.7 km in Ontonagon County to the village of Ontonagon, where it flows into Lake Superior.

National Wild and Scenic River designation

On March 3, 1992, the following reaches of the Ontonagon's upper tributaries were collectively designated the Ontonagon National Wild and Scenic River: The upper courses of the East and Middle branches in the Ottawa National Forest; the Cisco Branch in its entirety; and approximately the middle section of the West Branch, from Cascade Falls to the Victoria Reservoir.

Other historical significance

A very large mass of solid, nearly pure copper, the Ontonagon Boulder, was removed from the west branch of the Ontonagon River and transported in 1842 to Detroit, where it was weighed at 3708 pounds. It is displayed in Washington, D.C., at the Smithsonian National Museum of Natural History.