North Fork Koyukuk River


This river flows from the south flank of the Arctic Divide through broad, glacially carved valleys in the rugged Endicott Mountains of Alaska's Central Brooks Range. It passes between the "Gates of the Arctic" at Boreal Mountain and Frigid Crags. The North Fork joins the Middle Fork and can be run all the way to Bettles Field.

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Designated Reach

December 2, 1980. The segment within Gates of the Arctic National Park.

Outstandingly Remarkable Values


Despite being only cursorily surveyed, the valley contains a high density of archeological sites. At least 86 historic and prehistoric archeological sites are known from the North Fork within Gates of the Arctic National Park and Preserve, and the vast majority are immediately adjacent to the river’s course. One unique aspect of the North Fork is that portions of this valley were unglaciated at the end of the last ice age, and the area was thus available to human occupation by the very earliest inhabitants of Beringia. The valley was also a major east-west intraregional travel corridor in prehistory, as demonstrated by the frequent occurrence along the North Fork of obsidian that derives from a major source on the Koyukuk’s main stem some 200 miles to the southwest.


The early inspiration for the creation of a vast northern national park can be traced back to a U.S. Forest Service forester named Bob Marshall who arrived in Alaska in 1929 looking for what he called “blank spaces on maps.” The North Fork Koyukuk River is the country Robert Marshall celebrated in his classic writings on Alaska and on the concept of wilderness.


Excellent hiking opportunities and remarkable scenery have made this location a highly desirable wilderness backpacking area within the Brooks Range. Additionally, the limited number of users throughout the North Fork contributes to a wilderness-type experience. The North Fork also provides backpacking access to the Tinayguk River, which allows the visitor to travel between the John River and North Fork Koyukuk River drainages. The combination of demanding whitewater in the upper river region and a gradient of vegetation changes—in addition to the river’s clear water—provides an interesting and desirable rafting experience


Frigid Crags and Boreal Mountain form the Gates of the Arctic, the iconic passage to the Gates of the Arctic National Park, as described by Robert Marshall. Within the central Brooks Range, the Endicott Mountains’ rugged peaks transition into large glacial valleys. Mount Doonerak, the highest mountain on the North Fork (at 7,610 feet), provides a significant contrast in size to adjacent peaks. Gray Mountain, Blackface Mountain, and Redstar Mountain exemplify the differences in coloration among the mountains in the area. The alpine regions of the North Fork present characteristically impressive views throughout this stretch of river.

Managing Partners And Contacts


Wild — 102 miles; Total — 102 miles.
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