Koyukuk National Wildlife Refuge
The 3.5 million-acre Koyukuk Refuge is a classic river floodplain that is bisected by the Koyukuk River and surrounded by rolling, low mountains. The Koyukuk River drains the southern side of the Brooks Range before merging into the Yukon River 500 miles later, making it the third largest river in Alaska.
Within the refuge the river is surrounded by oxbow lakes, sloughs and shallow seasonally-flooded basins called grass lakes.
This tapestry of rich wetlands combines with lowland forests to support a wide variety of birds. Thousands of waterfowl, primarily wigeon, pintail, scaup, white-fronted geese and Canada geese are joined by both trumpeter and tundra swan on the Koyukuk's lush breeding grounds each spring. The refuge streams and lakes also sustain large fish populations including king, silver and chum salmon that migrate up the Yukon River. The Three Day Slough area supports about five moose per square mile while the Western Arctic Caribou Herd, numbering more than 425,000 animals, migrates through Koyukuk and the 300 strong Galena Mountain Caribou Herd lives within the refuge year round.
Also located within the Koyukuk Refuge are the Nogabahara Sand Dunes. These dunes were formed thousands of years ago when sand exposed by receding glaciers was blown up against the Nulato Hills. Today the active dune area extends across 16,000 acres and contains individual dunes up to 200 feet in height and 300 feet or more in length. Nogabahara Sand Dunes are relatively inaccessible and are a designated wilderness area within the National Wilderness Preservation System.