Refuge lands total over in eleven geographic units from Kittery to Cape Elizabeth, Maine. In 1989, the refuge boundary expanded to include salt marsh, freshwater wetlands, and "critical edge" uplands around each of the nine divisions. In addition, the Biddeford Pool Division, the tenth division of the refuge, was created. This division serves as a key staging area in southern Maine for a large number and diversity of shorebirds. In 2007 the final Comprehensive Conservation Plan was signed, adding the eleventh division, York River Division. When land acquisitions are complete, the refuge will be about in size.