The Wenaha River is a tributary of the Grande Ronde River, about 22 miles (35 km) long, in the U.S. state of Oregon. The river begins at the confluence of its north and south forks in the Blue Mountains and flows east through the Wenaha–Tucannon Wilderness to meet the larger river at the small settlement of Troy. A designated Wild and Scenic River for its entire length, the stream flows wholly within Wallowa County.