dumps; gravel removal was completed prior to breakup. Most disturbed gravel 

 bars contained sparse vegetative cover consisting of herbaceous plants and 

 scattered young willows; however, one 2-ha island vegetated with a mature 

 willow thicket was removed. The overburden and slash from this island were 

 piled within the gravel removal area. 



Diversion dikes were constructed to direct flow from the gravel removal 

 area, and a 2-ha gravel stockpile was located on the edge of the floodplain. 

 The 2-m incised floodplain bank was cut in five locations to gain access to 

 the floodplain or to reach underlying gravel deposits. Approximately 375 m 

 of bank were disturbed. Rehabilitative measures were not employed following 

 the activity, hence all dikes, stockpiles, overburden piles, and cut banks 

 remained during the site visit. Various aspects of this site are shown in 

 Figures 5 and 77. 



NORTHERN INTERIOR 



General Description of Region 



All six study sites in this region are located in the Koyukuk River 

 watershed. Four sites, Dietrich R i ver-Upstream, Dietrich River-Downstream, 

 Middle Fork Koyukuk R i ver-Upstream, and Middle Fork Koyukuk River-Down- 

 stream, are in the Central and Eastern Brooks Range Section of the Arctic 

 Mountains Physiographic Province, while Jim River and Prospect Creek, are in 

 the Kokr i ne-Hodzana Highlands Section of the Northern Plateau Physiographic 

 Province (Wahrhaftig 1965). The Central and Eastern Brooks Range Section is 

 characterized by flat-floored glacial valleys and east-trending ridges that 

 rise to elevations of approximately 1,800 m (Figure 6). Minor tributaries 

 typically flow east and west, parallel to the structure imposed by the belts 

 of sedimentary and volcanic rocks. Valley walls are dominantly coarse rubble 

 deposits associated with steep sloped mountains which have a high percentage 

 of bedrock exposures. The valley bottom in the vicinity of the Middle Fork 

 Koyukuk River study sites consists of unmodified moraines and associated 

 drift. The area is underlain by continuous permafrost. The Jim River and 

 Prospect Creek sites, in the Kokr i ne-Hodzana Highlands, are in an area of 



51 



