Nutuvukti Lake and Fen

Nutuvukti Lake, one of the largest lakes in Northern Alaska, lies between two mountain ridges in the Kobuk Preserve portion of Gates of the Arctic National Park and Preserve.

Nutuvukti Lake is one of the most scenic and interesting places in Gates of the Arctic National Park and Preserve. Nutuvukti Lake lies in a trough between two mountain ridges covered with dwarf subarctic spruce forest and alpine tundra. Six miles long, it is smaller than its more famous neighbor, Walker Lake, but still one of the largest lakes in northern Alaska and home to lake trout, arctic grayling, arctic char, northern pike, and whitefish.

Nutuvukti Lake is in the southern part of Gates of the Arctic National Park and Preserve, Alaska. North of the lake are the fen, glacial moraine, and proposed road.

What is a Fen?

A fen is a type of wetland where the ground is composed of peat, partly decomposed plants. The spongy mass of peat is saturated with water and the vegetation is mostly grass-like sedges, usually with some moss and low shrubs. The water in a fen is not strongly acidic, because it originates from groundwater that contains dissolved mineral nutrients. In a fen the water seeps slowly downhill in a wide sheet, like a "River of Grass," as our most famous fen--the Florida Everglades--is sometimes called.

Looking west from the middle of Nutuvukti Fen. Sedges dominate the fen’s vegetation, with mosses and low shrubs also growing in the saturated peat.

An aerial photograph of the western side of Nutuvukti Fen, showing the patterning. To give an idea of scale, the green wavy lines (vegetated ridges) are about 10-15 feet wide. The water in Nutuvukti Lake comes as runoff from the nearby mountain slopes and from the fen that lies on its northern shore. This fen is one of the few, and perhaps the largest, patterned fens in all of interior Alaska. It is called "patterned" because it is covered with an intricate pattern of low ridges and pools.

A pond formed by the melting of ice in the ground at the edge of Nutuvukti Fen.

Permafrost and Water Flow

Most of the landscape around Nutuvukti Lake is underlain by permafrost--ground that stays frozen year-round. Only the top foot or two thaws each summer, so water from snowmelt and summer rains flows downslope quickly over the permafrost and never soaks deeply into the ground. As it flow downslope it concentrates into "water tracks," which are visible as green lines of vegetation. The permafrost contains ice bodies, and if it thaws the ground subsides to form pits and ponds.

The Nutuvukti moraine north of the lake and fen is one of the few places in the area without permafrost.

Just north of the Nutuvukti Fen is an area of low hills and rocky soil, called a glacial moraine, that marks the end of a glacier during the last ice age. This moraine is one of the few places on this landscape that lacks permafrost, which allows water to soak deeply into the ground and move underground into the fen and then on to the lake.

Water runs conduct downslope over permafrost to Nutuvukti Lake (visible at the bottom of this aerial photograph). The water tracks appear as green stripes of dense vegetation that are about 50 feet wide.

The law that established Gates of the Arctic National Park and Preserve provides for a transportation corridor to access the Ambler Mining District. The State of Alaska is considering a road route that passes near Nutuvukti Lake. There is an supplemental environmental impact statement nearing completion that provides recommendations for the road.