The Umatilla River is an 89-mile (143 km) tributary of the Columbia River in the U.S. state of Oregon. Draining a basin of 2,450 square miles (6,300 km2), it enters the Columbia near the city of Umatilla in the northeastern part of the state. In downstream order, beginning at the headwaters, major tributaries of the Umatilla River are the North Fork Umatilla River and the South Fork Umatilla River, then Meacham, McKay, Birch, and Butter creeks. The name Umatilla is derived from the Native American name for the river, which was first recorded as Youmalolam in the journals of the ... Source: Wikipedia