A total of approximately 4,000 acres were listed for sale in Oregon's Umatilla County recently, representing a combined approximately $48 million in Umatilla County farms and ranches for sale. Umatilla County ranks 23rd in the state for the combined amount of land currently advertised for sale. Of all land for sale in Umatilla County, Hermiston had the most land for sale. Umatilla County is one of the ten largest counties in Oregon (3,231 square miles). It's located in the Eastern Oregon region of Oregon.