Lake Andes National Wildlife Refuge in South Dakota protects a natural spring-fed lake and the surrounding wetland and prairie-edge habitat across 5,638 acres. Managed by the U.S. Fish and Wildlife Service, it includes only 938 acres of direct federal ownership, with most of the rest preserved through easements. The lake changes dramatically, drying up about every 20 years, a cycle that has influenced water management and wildlife use. Two dikes divide it into three sections to help retain water during dry summers. The refuge supports more than one hundred nesting bird species, along with mammals such as white-tailed deer, coyote, badger, and muskrat.