ZILLAH, WA Zillah is an agricultural community located in Yakima County, Central WA. The quaint community is experiencing the early stages of urbanization. Zillah has grown into a residential and business center in the heart of one of the richest agricultural regions in Washington State. In recent years, Zillah has become known for its 20+ excellent wineries, and whose tasting rooms in the wineries draw in tens of thousands of visitors throughout the year.