The Wallowa River is a tributary of the Grande Ronde River, approximately long, in northeastern Oregon in the United States. It drains a valley on the Columbia Plateau in the northeast corner of the state north of Wallowa Mountains. It rises in southern Wallowa County, in the Wallowa Mountains in the Eagle Cap Wilderness of the Wallowa–Whitman National Forest. It flows generally northwest through the Wallowa Valley, past the communities of Joseph, Enterprise, and Wallowa. It receives the Minam River from the south at the hamlet of Minam, then flows north another to join the Grande Ronde along the Wallowa–Union county line approximately north-northeast of Elgin and about from the larger river's confluence with the Snake River.