About the Refuge Surrounded by development and industry, the
Antioch Dunes National Wildlife Refuge supports the last known
populations of the endangered Antioch Dunes evening primrose,
the Contra Costa wallflower, and the Lange's metalmark
butterfly. Last Dunes Standing Antioch Dunes National Wildlife
Refuge is the only national wildlife refuge in the country
established to protect endangered plants and insects – the
Antioch Dunes evening primrose, the Contra Costa wallfl ower,
and the Lange’s metalmark butterfly. Created in 1980, the
55-acre refuge was once part of a larger sand dune system that
stretched two miles along the southern bank of the San Joaquin
River east of the City of Antioch. The sand dunes were formed by
ancient deposits of glacial sands carried downriver from the
Sierra Nevada. Over thousands of years, ocean winds and bay
tides slowly shaped these aeolian (wind-blown) sands into dunes
that approached 120 feet in height. Isolation of these dunes
resulted in the development of species of pla