Occoquan Bay National Wildlife Refuge is a 644-acre protected area in Woodbridge, Virginia, at the meeting of the Occoquan and Potomac rivers between Belmont Bay and Occoquan Bay. About half the refuge is wetlands, with forest and native grasslands adding an unusual variety of habitats in a small area. The land evolved from Dawson Beach, a tourist destination, to a U.S. Army radio station and later classified research site under Harry Diamond Laboratories. Conditions created by military use helped preserve open grasslands after the base closed. Formally established in 1998, the refuge now supports remarkable biodiversity, including more than 220 bird species, over 600 plant species, and 65 butterfly species.