number of units. See also Bixby State Preserve Sources FWS overview and planning document , Retrieved July 24, 2007 FWS discussion of ecology Retrieved on July 20, 2007 FWS site giving further information Retrieved July 7, 2007 FWS visitor information Retrieved July 7, 2007 Recreation.gov site FWS Conservation plan Retrieved on June 8, 2007 Friends of the Upper Mississippi Retrieved on June 8, 2007 External links Driftless Area National Wildlife Refuge - official site Driftless Area Initiative Protected areas of Allamakee County, Iowa Protected areas of Clayton County, Iowa Protected areas of Dubuque County, Iowa Protected areas of Jackson County, Iowa National Wildlife Refuges in Illinois National Wildlife Refuges in Iowa National Wildlife Refuges in Wisconsin Driftless Area Protected areas established in 1989 Protected areas of Richland County, Wisconsin Protected areas of Grant County, Wisconsin 1989 establishments in Wisconsin 1989 establishments in Illinois 1989 establishments in Iowa Protected areas of Jo Daviess County, Illinois