The Antioch Dunes National Wildlife Refuge is located in the San Francisco Bay-Delta area, along the southern shore of the San Joaquin River. It was the first national wildlife refuge in the country established to protect endangered plants and insects. Established in 1980, the refuge provides protection for three endangered species: Lange's Metalmark butterfly, Antioch Dunes evening primrose and Contra Costa wallflower. The refuge and a few acres of surrounding lands contain most of the remaining habitat for these three species and are all that remain of a nine kilometer stretch of sand dunes formed during glaciation periods. Isolation of this sand dune habitat resulted in the development of a unique assemblage of plants, insects, and reptiles. Due to the sensitivity of the habitats and the endangered species, the refuge is not open to unsupervised use by the public. However, refuge staff and local educators conduct on-site environmental education efforts through guided tours and special events. In addition, volunteers regularly assist refuge staff with habitat restoration projects and endangered species surveys.