Encompassing approximately 18,000 square miles, the Columbia Valley Region is 185 miles wide and 200 miles long. Separated from Seattle's rainy, marine climate by the Cascade Mountains, the Valley is shielded by the rain shadow of this north/south-stretching barrier, and it experiences annual rainfall of only 6 - 8 inches. Nearby river systems bring vineyards the additional water needed to produce premium wine grapes.
