The Columbia Plateau, also called the Columbia Basin, is an arid sagebrush steppe and grassland, surrounded on all sides by moister, predominantly forested, mountainous ecological regions, such as the
North Cascades (1J) and
Eastern Cascades Foothills (1I) both to the east, the
Blue Mountains (2F) to the south and the
Northern Rockies (3F) to the west.
This region is underlain by basalt as much as two miles thick in some area and this basalt will oftentimes be seen on the surface at coulees or as huge basalt boulders. The basalt is covered in many places by loess deposits, which is a rich, dust-like soil, most of which have been extensively cultivated for wheat, especially in the eastern portions of the region where precipitation amounts are greater. However, irrigation is used throughout the ecoregion to carry water from lakes and rivers directly to the crop lands.
Some parts of this ecoregion has the appearance that a huge flood scoured the surface down to the bedrock. Large coulees are recurring throughout the area and often the coulees have signs of lava flow.
The Yakima Indian Reservation, which was spelled Yakima until changed by the native people in 1994, is a Native American reservation in Washington state composed of a federally recognized tribe known as the Confederated Tribes and Bands of the Yakima Nation, indigenous peoples who are descendants of a couple of the twelve
Sons of Hadoram, and which modern tribes are made up of Klikitat, Palus, Wallawalla, Wanapam, Wenatchi and Yakima from those who were previously of the Pacific Interior Region Tribes together with the Wishram (Wasco) who were previously of the Pacific Coastal Region Tribes.
Yakima River Canyon Recreation Sites (BLM) Campground
