Most don't realize the "Great North American Desert" isn't relegated to the Southwest US.

It actually stretches through central and eastern Oregon straddling the OR/ID border and comes to a point traveling through central WA state. It's northern tip is sandwiched between the Kittitas valley and the flats west of Airway Heights, WA. It very roughly follows the route of the Columbia river. In fact, if you look at the area near Grand Coulee Dam and Banks Lake you will see the extreme northern reaches of the GNAD.

Following the river as it flows south will take you through high-desert areas around Yakima and Tri-Cities. Note how most of the area farms in this region rely on irrigation. Without the dams and irrigation canals/projects, this land would not be as productive at best, and would revert to unfarmable deserted lands at worst.

If I might, I want to throw out how WA state has many very diverse bio-regions, including a rainforest on the Olympic peninsula, and all the lush rolling hills of farmland of the Palouse region south of Spokane.

Aside from the occasional mountain blowing up every 500 years or so, WA state is awesome!