JOHNSON RIDGE STATE NATURE PRESERVE - 208 ACRES Main Feature: Summer prairie wildflowers. Location: Located in Adams County approximately 3 1/2 miles north of West Union on Unity Road (County Road 10), east of SR 247. No facilities. Johnson Ridge State Nature Preserve Unity Road West Union, Ohio 45693 Phone: (937) 544-9750 208 acres-Known for the many summer prairie wildflowers. Located 3 1/2 miles north of West Union on Unity Road (County Road 10)east of SR 247.