The U.S. Fish and Wildlife Service is proposing to 'list the island marble butterfly (Euchloe ausonides insulanus) as an endangered species and designate critical habitat under the Endangered Species Act.' The potential critical habitat designation consists of '812 acres (329 hectares) on the south end of San Juan Island, San Juan County, Washington.' The U.S. Fish and Wildlife Service has also completed 'a draft economic analysis of the proposed designation of critical habitat for the island marble butterfly', which is now available for public review.