THE UMATILLA COUNTY LAND BRIEF
Land in the
Umatilla Plateau setting.
Umatilla County has 3,215.5 square miles of land in Oregon. 9 mapped landscape regions meet across Umatilla County: Umatilla Plateau, Maritime-Influenced Zone, Pleistocene Lake Basins, among others.
Basalt underlies this dry plateau of grassland and sagebrush. Windblown soils cover some uplands, while ancient flood paths exposed rock across the region's scabland terrain.
Regional context: Columbia Plateau ↗ · Regional mapping across the county footprint
Where the landscape changes
Umatilla County intersects 9 mapped regional units. The largest mapped shares are:
- Umatilla Plateau25.7%
- Maritime-Influenced Zone21.9%
- Pleistocene Lake Basins16.1%
- Umatilla Dissected Uplands12.1%
- Mesic Forest Zone11.6%
Blue Mountains in Umatilla County
The Blue Mountains combine open mountain ranges and dissected volcanic uplands. The Wallowa and Elkhorn high country includes older granitic and metamorphic rocks above the surrounding lava landscape.
Read the regional source ↗Finding your parcel within Umatilla County
The atlas lists 22 cities, towns, townships, and Census communities associated with Umatilla County, including McKay, Tutuilla, Pendleton. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Umatilla County by land and water
The Census records 16.1 square miles of water within Umatilla County, or 0.5% of its total area. That share is close to Umatilla County’s 0.5%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Umatilla County has 160.8 times the land area of nearby Tutuilla CDP (20 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Grant County, Morrow County, Union County, Wallowa County within Oregon. A tract near one of these lines should be matched to the county identifier on its own records.

