Umatilla

Related Category: U.S. Physical Geography

(ŭm´´ətĭl´ə), river, c.85 mi (140 km) long, rising in NE Oreg. in the Blue Mts. It flows W past Pendleton, then NW to the Columbia River at the city of Umatilla (1990 pop. 3,046). The Umatilla project taps two of the river's tributaries for irrigation.