Buena is an unincorporated community in Yakima County, with a 2010 census population of 990. The community was not recognized in the 2000 census figures. Washington, United States. Buena is 3.5 miles north of Toppenish. Buena has a post office with ZIP code 98921. The settlement was originally named Springdale for a nearby spring, but its name was changed to Jonathan in 1918 to avoid conflicting with an existing Springdale when a post office was created.