The Rattlesnake Hills is a sub-region of the Yakima Valley AVA, centered on the city of Zillah. These hills form the northern boundary of the Yakima Valley and there are roughly 1,500 acres under vine. Elevations range as high as 3,000 feet, making this the highest point in the Yakima Valley. The heightened elevation creates a significant diurnal range and also helps to mitigate the dangers of frost damage. The Morrison Vineyard was the first planted in the region in 1968, by Chateau Ste. Michelle, as a source for Riesling and Cabernet Sauvignon. (Wine/Appellations)