Columbia River Plateau

Understand

Geology

Between 6-17 million years ago, flood after flood of volcanic basalt engulfed about of the Pacific Northwest, ultimately accumulating to a thickness of more than 6,000 ft, leading to a large lava plateau. Evidence links the concentrated heat source underneath the plateau to the hot spot that is underneath Yellowstone.

Much more recently, at the end of the last ice age, the channeled scabland coulees across the region were carved out by the cataclysmic Missoula floods, where massive glacial lakes to the east periodically released more water down the Columbia Gorge than flows out of all of today's rivers combined.

History

The skeletal remains of Kennewick Man, one of the oldest and most complete human remains found in North America, were discovered here and are dated to between 8,400 and 8,700 years ago. The peoples of the basin had a subsistence-based culture based on hunting, food-gathering and some forms of agriculture, as well as a dependency on salmon from the Columbia and its tributaries.

In 1836, a group of missionaries, including Marcus Whitman, established several missions near present-day Walla Walla, in the territory of both the Cayuse and the Nez Perce Indian tribes. Whitman's settlement would help establish the Oregon Trail. When Indian patients died in striking numbers to "European" diseases, while at the same time many white patients recovered, they held "medicine man" Marcus Whitman personally responsible, and executed Whitman and twelve other white settlers in 1847, triggering the Cayuse War. Around this time, the Washington-Canadian border was also worked out, and the region was fully opened to American settlers.

During the Great Depression, a series of hydroelectric dams were constructed along the Columbia River to increase the production of electricity, culminating with the completion of the Grand Coulee Dam in 1941, the largest concrete structure in the United States and the largest dam in the world at its construction. Making use of the region's water and energy resources, the Hanford Site played a major role in the construction of atomic bombs during World War II.

Climate

The plateau has a dry climate, in distinct contrast to western Washington. Despite the limited rainfall, agriculture is an extremely important business, as the soil is highly productive and irrigation, aided by dams along the Columbia River, is fairly widespread.

Cities

This article covers the Washington counties of Adams, Benton, Douglas, Franklin, Grant, Klickitat, Lincoln, Walla Walla, and Yakima. Broader definitions of the Columbia Plateau sometimes include the Palouse and the Oregon side of the Columbia Gorge.

Coulee Country

These channeled scablands are shaped from prehistoric flooding, interspersed with irrigated farming communities. This area includes Adams, Douglas, Grant and Lincoln Counties.

• Bridgeport — site of the Chief Joseph Dam
• Davenport — county seat of Lincoln County
• East Wenatchee — across the Columbia from Wenatchee
• Ephrata — county seat of Grant County
• Coulee City — on the south end of Banks Lake, near Dry Falls
• Grand Coulee (including Electric City and Coulee Dam) — home of the Grand Coulee Dam, the largest hydroelectric power producer in the country
• Moses Lake — largest city in this subregion
• Othello — a potato hub
• Quincy
• Ritzville — county seat of Adams County
• Soap Lake — a small town known for its healing mineral waters
• Waterville — county seat of Douglas County

Tri-Cities

The Tri-Cities are at the confluence of the Yakima, Snake, and Columbia rivers, in Franklin County and Benton County:

• Kennewick — the largest of the Tri-Cities
• Pasco — county seat of Franklin County
• Richland (including West Richland) — near the Hanford Site and Pacific Northwest National Laboratory

Other communities nearby:

• Benton City
• Connell

Klickitat County

• Goldendale — county seat of Klickitat County

Walla Walla County

• Walla Walla (including College Place) — the heart of Washington wine country, county seat of Walla Walla County
• Burbank
• Waitsburg

Yakima Valley

The farmland of the Yakima Valley consists of grapes, wheat, apples, and many other crops. It includes Yakima County and westernmost Benton County.

• Yakima (including Union Gap and Selah) — county seat of Yakima County
• Grandview
• Granger — a town decorated with dinosaurs
• Prosser — county seat of Benton County
• Sunnyside
• Toppenish — the city of murals
• Wapato
• Zillah — its gas station is a giant teapot

Other destinations

• Frenchman Coulee — a gorge lined with climbable basalt columns
• Sun Lakes-Dry Falls State Park — during the last ice age, Dry Falls occasionally carried more water by volume than all the rivers of the world combined

Get in

By plane

There are two small airports in this region with limited commercial air service: Yakima Airport (YKM) and Pasco Airport (PSC).

Seattle-Tacoma International Airport (SEA) and Portland International Airport (PDX) have international flights and domestic flights with most major airlines. Both are about 2-3 hours away by car.

By car

• Interstate 90 (I-90) leads into the heart of this region.
• From Seattle: Take I-90 east to I-82, east of Ellensburg.
• From Spokane: Go west on I-90 to US-395 in Ritzville and go south into Tri-Cities.
• Interstate 82 (I-82) is the main east-west highway through the south part of this region, following the Yakima River. I-82 connects Ellensburg at I-90 to I-84 south of Hermiston in Oregon.
• From Portland or Boise: Take I-84 to I-82 in Hermiston. If coming from Portland one can also go north on US 97 into this region, from The Dalles to I-82 south of Yakima.
• US Highway 12 (US-12) goes across from Chehalis (from Exit 71 of I-5) to I-82 in Yakima. US-12 goes concurrent on I-82 from Yakima to Tri-Cities and then continues east of Tri-Cities to Walla Walla.
• US Highway 97 (US-97) is the main north-south highway along the western edge of the Columbia River Plateau. It goes north south from The Dalles to Yakima, Ellensburg and Wentatchee.
• US Highway 395 (US-395) is the north-south highway through the eastern side of this region. It goes from I-84 south of Hermiston along I-82 to Tri-Cities. From Tri-Cities it goes northeasterly towards I-90 in Ritzville through Othello. Continuing north it goes east along I-90 to Spokane and going south from Hermiston it goes along I-84 towards Pendleton.

By train

Amtrak's Empire Builder stops in Pasco (on the Portland branch) and Ephrata (on the Seattle branch).

Get around

• Interstate 182 (I-182) crosses the Columbia River in the Tri-Cities.
• Residents of the Tri-Cities commonly use State Route 240 (WA-240), which is adjacent to the Columbia River, to travel between Kennewick, Richland, and Pasco quickly.

Stay safe

Rattlesnakes are commonly found outside of developed areas. Don't touch them! It is best to freeze and back away as slowly as possible. Their venom is rarely fatal if treated promptly.

During the summer months, the temperature often exceeds 100°F. If you are to be outside for long periods of time, drink plenty of water and limit the intake of alcohol and caffeine to prevent dehydration and heat stroke.

Go next

• Eastern Oregon, to the south
• Southwest Washington, to the west
• North Central Cascades, to the north
• Palouse, to the east