Major streams originate from the Brooks Range and are structurally controlled by the bedrock. Most streams are swift, but portions may be braided across gravel flats. Perennial streams have algae-covered rocky bottoms. During spring snowmelt and breakup of river ice, flooding and channel shifting are common. Oxbow lakes along major stream valleys are the predominant type of lake in this ecoregion.
Most lake beds are organic muck, but some are sandy.
Soils Principal soils are Histic Pergelic Cryaquepts, Pergelic Cryaquepts, and Pergelic Ruptic-Histic Cryaquepts. Dominant soils in valleys and on long slopes formed in silty or loamy colluvial sediments. On hills and ridges, most of the soils are composed of very gravelly materials eroded from sedimentary rock. The dominant soils in the Noatak Valley are poorly drained and are derived from very gravelly glaciofluvial material from limestone rock in the surrounding mountains. Well drained soils occur on hilly moraines of the valley, formed from very gravelly, nonacid and calcareous drift.