Malheur Lake. During the 1930s, the P Ranch near Frenchglen, Oregon and Sod House Ranch south of Malheur Lake were incorporated into the refuge, adding to the protected wildlife area. In 1940, the name of the refuge was officially changed to the Malheur National Wildlife Refuge. In 1941, the United States Government purchased of Double-O Ranch land from the Hanley family for $118,000, adding it to the adjacent Malheur wildlife refuge to preserve shorebird habitat and protect critical waterfowl nesting areas. The Double-O Ranch included the lower Silver Creek drainage and several lakes that provided water to irrigate the property. The ranch's riparian areas, lake shore wetlands, and grassy meadows provided habitat for migratory birds traveling along the Pacific Flyway. A number of natural warm springs made the lakes a winter haven for non-migratory birds as well. Numerous birds including wild swans, Canada geese, great white egrets, herons, pelicans, and many duck species nested on the Double-O Ranch. Because the ranch played an important role in the development of the cattle industry in the western United States, the Double-O Ranch was listed on the National Register of Historic Places as a historic district on 25 October 1982. The district covers ; however, there are only two of the original ranch buildings remaining at the site. Both of these historic structures are located on the compound of Double O Station, a year around field station operated by the United States Fish and Wildlife Service. Structures After the original Double-O Ranch buildings were burned by Indians in 1878, the ranch was rebuilt by Riley and Hardin. Between 1879 and 1903, a number of buildings were constructed at the site; however, only two of those buildings remain. There are no buildings remaining from the Hanley era. The United States Fish and Wildlife Service added three non-historic building in the 1950s to support refuge operation. The two remaining historic structures include a log cabin and a blacksmith's shop, both dating from the 1880s. In 1982, when the historic district was created, the cabin was in good condition, but the blacksmith's shop was partially collapsed. The log cabin was used as the blacksmith's residence. It is a -story, hand-hewn log structure. All of the logs have been squared and have dovetailed ends that lock the log joints together. The cabin's footprint is by . The cabin has a wooden floor and a cedar shingle roof.