Kugruk River

Kugruk River
Country	United States
State	Alaska
Borough	Northwest Arctic
Source	near Imuruk Lake
- location	Seward Peninsula
- elevation	1,311 ft (400 m)
- coordinates	65°41′24″N 163°15′05″W / 65.69000°N 163.25139°W / 65.69000; -163.25139
Mouth	Kugruk Lagoon of Kotzebue Sound on the Chukchi Sea
- location	5.5 miles (8.9 km) southeast of Cape Deceit
- elevation	0 ft (0 m)
- coordinates	66°00′22″N 162°40′13″W / 66.00611°N 162.67028°W / 66.00611; -162.67028Coordinates: 66°00′22″N 162°40′13″W / 66.00611°N 162.67028°W / 66.00611; -162.67028
Length	60 mi (97 km)
Location of the mouth of the Kugruk River in Alaska

The Kugruk River is a stream, 60 miles (97 km) long, in the northwestern part of the U.S. state of Alaska. It is the largest tributary of the Kuzitrin River. It begins near Imuruk Lake on the Seward Peninsula and flows generally north to Kugruk Lagoon, at Kotzebue Sound on the Chukchi Sea. The river enters the lagoon 5.5 miles (8.9 km) southeast of Cape Deceit in the Northwest Arctic Borough.

In the late 19th century, the river's Inuit name was reported as "Koogroog" (not to be confused with the Kougarok River), but variants in other documents referred to it as "Mammoth" for mammoth bones found nearby, or "Swan". In 1904, the United States Board on Geographic Names approved the name "Kugruk", which is how the river was identified in court records. Some mining was reported on Windy, Neva, North Fork, Coarse Gold, Henry, Taylor, and Macklin creeks, tributaries of the Kugruk River.

The Kugruk River is a large northern tributary of the Kuzitrin. It has a length, neglecting meanders and minor bends, of about 60 miles. Throughout the greater part of its course, it occupies a canyon cut in a high plateau-like upland, which varies in elevation from 1,200 to 1,800 feet. About 10 miles above its mouth, the Kugruk River emerges upon the Kuzitrin lowland from its canyon. The course of this canyon is approximately north and south for 30 miles, and follows in a general way the strike of the bed rock. Below the mouth of Coarse Gold Creek the canyon is sharply cut, and no gravel benches or extensive gravel bars were observed in the creek bed. Above Coarse Cold Creek the valley broadens. At this place there are broad benches, about 20 feet above the river bed. cut on the upturned edges of the schists, and covered with several feet of gravel. Similar gravel benches occur occasionally as far as the mouth of Taylor Creek, above which point the creek bed was not examined in detail. At the mouth of Macklin Creek, the Kugruk River turns sharply, and above this place it flows in an east-west direction from its source at the east base of Kugruk Mountain. The bed rock along the Kugruk River is generally highly metamorphosed, consisting of mica-schists and calcareous schists, with large intrusions of greenstone. The greenstone is schistose, but has a porphyritic texture, the phenocrysts being hornblende, while the groundmass is made up essentially of epidote, hornblende, quartz, and chlorite, mostly secondary minerals.