of this report. A final set of mitigating measures, construction guidelines, 

 and stipulations can be arrived at only after DNRC has completed its multi- | 

 disciplinary review of the project, and after public conment has been received " 

 as I'equired by the Major Facility Siting Act. 



HABITAT ALTERATION 



The habitat of an animal species iiiay be defined as a type of area where 

 the species can generally be found, and which provides for all life require- 

 ments of the species. Although carrying capacity "'s determined by a great 

 many environmental features, such as colonization rates, competitive milieu, 

 etc., habitat quality is often considered the principal detenninant of carry- 

 ing capacity: if habitat is altered in such a way that it no longer meets 

 the life requirements of a population, carrying a capacity is ''e'duced. Species 

 differ considerably in their ability to adapt to different habitats. Some 

 species are very stenotopic, that is, restricted to a narrowly-defined range 

 of environmental conditions. "K-selected" species (MacArthur and Wilson 1967), 

 such as the harlequin duck, pilea"i,ed woodpecker, and wolverine, are usually 

 very stenotopic and are especially vulnerable to habitat alteration. Such 

 species are often restricted to late-successional habitats. Eurytopic species 

 are those which can tolerate wide extremes in environmental conditions. These 

 are often "R-selected" species, such as most rodents and m^^.ny songbirds, which 

 have high reproductive rates and the ability to quickly colonize vacant habitats. 

 Eurytopic species are generally characteristic of early successional stages and 

 occupy a wide range of habitats. 



The proposed Kootenai Falls project would affect a variety of species ^ 

 through changes in aquatic and riparian habitats. These habitat changes 

 would result primarily from impoundment of the Kootenai River and relocation 

 of the railroad, and are discussed in detail below. 



Changes in Riparian Habitats Due to Impoundment and Railroad Relocation 



The construction of Libby Dam has had a profound effect on the downstream 

 riparian environment of the Kootenai River. Prior to impoundment in 1972, the 

 pattern of discharge of the Kootenai River was typical of that of large montane 

 rivers: high flows occurred with spring runoff, and low flows occurred in win- 

 ter. Libby dam reversed that pattern, and now peak flows generally occur in 

 winter (Figure 11). Furthermore, the frequency of extremely high (flood) run- 

 off has been reduced and the daily variation in flows is extreme. Flows often vary 

 by 424 cm,s (15,000 cfs) or more from morning until evening each day in winter. 

 This alteration in flow regimes has undoutedly influenced the pattern of succes- 

 sion in riparian plant comnuni ties, both by eliminating the "flood disclimax" 

 successional pattern and by allowing relatively high flows to scour a portion 

 of the riverbanks almost any day of the year. The proposed Kootenai Falls 

 project would superimpose further changes on those brought about by Libby 

 Dani, as discussed below. 



Littoral Habitats . The term "littoral" is used here as in marine ecology 

 i.e., to refer to the zone between high and low water marks. In order to ade- ^^ 

 quately assess potential effects of the proposed dam on littoral habitats (which^ 

 are largely limited in the project area to gravel bars and bare rock), it is 



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