Antioch Dunes National Wildlife Refuge protects a rare and fragile sand dune ecosystem near Antioch, California, along the south shore of the San Joaquin River-Stockton Deepwater Shipping Channel. Established in 1980 and managed by the U.S. Fish and Wildlife Service, it was set aside to help preserve three endangered species: the Lange's metalmark butterfly, the Antioch Dunes evening primrose, and the Contra Costa wallflower. After severe habitat decline, especially for the butterfly, restoration became central to the refuge. In 2013, dredged sand from the river began being returned to the dunes and replanted with native species to rebuild habitat and support recovery.