From the City of Mattawa website
Of course, this doesn't contradict Alessandro's notions. Growing good grapes in optimum conditions is just the beginning. How it's turned into wine and the history, the individuals involved and the stories that wine tells are what give it depth and resonance. The simple caveat is that terroir itself doesn't necessarily mean good wine. The word is used largely for marketing purposes.
I've been enchanted by one of Washingon's most famous terroirs since long before anyone imagined grapes being grown there. The Wahluke Slope is a long stretch of desert reaching out from Mattawa, a small town, largely Hispanic, near the banks of the Columbia River. The slope was impressive for its stark nothingness. Now there are acres of vines that stretch across that formerly barren expanse. Where the vines end, the desert begins.
There are now a couple of wineries near Mattawa. I haven't tasted their wines. But I can imagine a evening along the river on the south end of the Big Bend; a hot summer day becoming cool and quiet. A soft wind blowing across the river's gently flowing expanse. The air smelling like grasshoppers. The evening sky filling up with the Milky Way. With a big glass of Ginko Forest grenache and maybe some taquitos de lengua to assist me... I think I might reconsider terroir yet again.