 It lies within the floodplain of the Koyukuk River, in a basin that extends from the Yukon River to the Purcell Mountains and the foothills of the Brooks Range.This region of wetlands is home to fish, waterfowl, beaver and Alaskan moose, and wooded lowlands where two species of fox, bears, wolf packs, Canadian lynx and marten prowl.The Northern Unit of the Innoko National Wildlife Refuge, commonly known as Kaiyuh Flats, is managed as part of the Koyukuk/Nowitna Refuge Complex.