The town of Umatilla sits nestled between the Columbia and Umatilla Rivers. The Columbia forms the northern boundary of the Umatilla River Basin, draining 4,545 square miles with elevations of 270 feet near the Columbia to 3,000 feet at the base of the Blue Mountains. Sedimentary deposits of loess, glacial stream deposits, windblown silt, and fine clay deposited during catastrophic Ice Age floods make the composition of the land between the river and the mountains ideal for agriculture. As little as 8 to 10 inches of rainfall per year along the river makes irrigation necessary for farming the rich soils of the region.
