The pre-settlement vegetation of the area was a mixture of prairie, wetland, and aspen parkland. In 1893, Eldor Omdahl's grandfather, John Hanson, emigrated from Norway. He homesteaded the 160 acres surrounding the Sanctuary headquarters. After passing through several owners, including the Federal Land Bank during unfavorable economic times, Eldor purchased the farm in 1949. That same year Eldor began planting trees on the farm in recognition of the conservation value of trees. In 1959, Eldor began developing ponds and waterways for the purpose of retaining water, in sharp contrast to the prevailing practice of draining wetlands. In 1981, Eldor and Stella Omdahl gave 640 acres of land to the Agassiz Audubon Society as a gift to establish a wildlife sanctuary. The couple, who reside in one of the two homes at the Sanctuary, were recognized as the West Polk county 2001 Conservation Cooperators for their lifetime contributions and acheivements in conservation.