[1] Archeological work at Lake Ilo NWR in the 1990s resulted in creating one of the largest assemblages of Paleo Indian artifacts found on land managed by the U.S.

[3][4] The region in which Lake Ilo NWR is located was one of the last to be settled by white settlers on the Great Plains of the United States.

The dam was completed in 1938 and the following year, U.S. President Franklin D. Roosevelt signed a congressional bill designating the new lake and the surrounding area as a National Wildlife Refuge.

Additionally, numerous bones of now extinct mammal species assist in determining the biodiversity of the region at the end of the ice age.

The prairie ecosystem of the region receives only 16.8 inches (42 cm) of precipitation annually so the lake provides nesting habitat and a sustainable water supply for hundreds of migratory waterfowl and other birds.

[7] A total of 226 species of birds have been observed at Lake Ilo NWR, including the endangered whooping crane, and the threatened bald eagle and piping plover.

[8] During fall migrations, as many as 100,000 waterfowl such as Canada geese, mallards, northern pintail, blue-winged teal, double-crested cormorant and great blue heron can be seen each year.

Wildlife viewing is available from a 1-mile (1.6 km) nature trail which is located on the north shore of Lake Ilo, as well as from gravel roads.

[13] The refuge is located 1 mile (1.6 km) west of Dunn Center, North Dakota on Highway 200, and is only open during the daytime.