Umatilla is a city in Umatilla County, Oregon, United States. It is named for the Umatilla River, which enters the Columbia River on the side of the city. The river is named after the Umatilla Tribe. The city is located on the south side of the Columbia River, and is located on U.S. Route 730 and I-82. The Umatilla Chemical Depot, and the Umatilla Chemical Agent Disposal Facility, is located four miles (6 km) southwest of the city, northwest of the intersection of I-84 and I-82. The population was 4,978 at the 2000 census. The 2006 estimate is 6,385 residents. Umatilla is part of the Pendleton–Hermiston Micropolitan Statistical Area.