It was established by the Bureau of Alcohol, Tobacco and Firearms (ATF), Treasury on December 13, 1984 after evaluating the petition filed by Drs, Walter Clore and Wade Wolfe of Prosser, Washington on behalf of Washington’s oldest and largest winery, Chateau Ste.

Michelle, understood the importance of obtaining appellation status to grow the reputation of the Northwest viticulture industry.

ATF included the entire valley within the viticultural area except the portion between Banks Lake and the Snake River.

The area is distinguished by its broadly undulating or rolling surface, cut by rivers and broken by long sloping basaltic uplifts extending generally in an east-west direction.

The northern latitude gives the areas two more hours of additional daylight during the summer growing season than California wine regions receive.

[1][5] Columbia Valley’s soils were formed by the Missoula Floods, a series of cataclysmic events over 15,000 years ago.

Most vineyards lie below the floodwaters, with soils of windblown deposits of sand and silt loess, overlying gravel and slackwater sediment with a basaltic bedrock.

The volcanic and sandy loam soil of the valley offers good drainage and is poor in nutrients, ideal in forcing the vine to concentrate its resources into the grape clusters.

North of the Rattlesnake Hills is a region commonly known as Columbia Cascade, but it is not a recognized American viticultural area.

The vast size of the appellation allows for an array of diverse microclimates among the various sub-appellations, but the entire region shares the common climate traits of cold winters and long dry growing seasons with low humidity.

This allows the grape more time to develop maturity in tannins as well as other aroma and profile characteristics that will be brought out in the resulting wines.

The longer growing season also allows the grapes to be harvested at a cooler temperature than in other more southerly wine regions.

[5] Deep winter freezes are the main climate threat to the grape growing industry of the Columbia Valley.

Many vineyards incorporate wind turbines to maintain air circulation around the grapes and stay warm enough to prevent frost.

[1] The rain shadow of the Cascade Range leaves the Columbia Valley with some areas receiving less than 6 inches (15 cm) of annual rainfall.