The Willamette Basin covers approximately 2,600,000 hectares (6,400,000 acres) and is comprised of a combination of forested and grassland ecosystems (EPA Federal Resister Document, Jan. 25, 2000). Upland and wetland prairies in the Willamette Valley are amongst the rarest ecosystems in North America. These ecosystems are complex and also poorly understood. To find out more about research on the Fender's blue butterfly range and extent of upland prairie ecosystems, go to: