necessary to examint- certain features of the current discharge regime from 

 Libby Dam. 



-igure 1? shows the typical seasonal pattern of discharge of the Kootenai 

 River at Kootenai Falls, as controlled by Libby Dam. It is evident from this 

 figure that, during a "typical" yesr, lowest flows occur April through June, 

 with relatively little daily variation, while highest flow^ occu*" in November 

 through January with considerable daily variation. NLIs proposal would not 

 affect this discharge regime, but would moderate its effects in the pool area. 

 Figure 13 shows the 'mpact of the project on the pattern of seasonal variation 

 in surface elevations of the Kootenai River, and Figure 14 shows the -i-npact 

 on the pattern of seasonal variation in width of the wetted perimeter (and 

 hence of the littoral zone) at three river cross sections. Pool elevations 

 would remair, fairly constant at 609. 6m (2000 feet), regardless of discharge , 

 for a distance of roughly 2.4 km (1.5 mi) upstream from the dam (NLI 1978; HA-25), 

 in contrast to the present regime of drastic year-long fluctuations in elevation 

 shown in Figure 13. Correspondingly, width of the littoral zone would be 

 drastically reduced should the project be constructed (Figure 14). At the 

 upper end of the pool (cross section 9, Figure 10), pool elevations 

 ^anqe from 509.7m (2000.2 ft) at a discnarge of 56 cms (2000 cfs) to 614. Im 

 (2014.5 ft) at 1400 cms (50,000 cfs) (NLI 1978:HA-17). Natural river eleva- 

 tions at these same discharges would be 608.1 m (1995.2 ft) and 614 m (2014.3 ft), 

 respectively. While all terrestrial vegetation would be lost dje to permanent 

 inundation below the 509.6 m (2000 ft) contour, some flood-tolerant riparian 

 vegetation may be able to persist below the 1400 cms (50,000 cfs) pool level 

 along the upper end of the pool, where it v.'ould only be inundated part of the 

 time (during very high flows). Actually, flows can be expected to be below 

 672 cms (24,000 cfs) 93 percent or more of the time (NLI 1978:H-2). Plant 

 species which can tolerate this much inundation, for example cottonwood and 

 willow (Teskey and Hinckley 1978), can thus be expected to survive along a 

 portion of the pool. If clearing is not carried out in this portion of the 

 littoral zone, as proposed by NLI, both living and dead vegetation which 

 persists will provide useful wildlife cover; construction costs will be re- 

 duced as well (Nelson et al. 1978). 



These changes in the characteristics of the littoral zone would have 

 important consequences for wildlife. It is likely that all gravel bar, 

 logjam, exposed rock, and bare rock habitats would be eliminated from along 

 the proposed pool; woody vegetation or grasses would probably colonize any 

 bare surfaces that remained along the new, stable shoreline. Scouring by 

 wery high discharges would occur very infrequently, as the 100-year flood 

 from Libby Dam is only 1456 cms (52,000 cfs) (NLI 1978-H-2). This would 

 eliminate much feeding habitat for dippers and spotted sandpipers, and would 

 also eliminate gravel bars which are important loafing habitat for waterfowl 

 (Taber and Raedeke 1976), and which would otherwise lead to serai willow commumties 

 important to beaver (Martin 1977). Willows presently established in the upper- 

 most littoral zone would probably be replaced by cottonwoods as sediments 

 are deposited (Martin 1977), and no new gravel bars or willow stands would 

 be produced since high discharges would occur so rarely. 



Stabilization of pool elevation, and consequent reduction in the littoral 

 zone, could have beneficial effects on a number of wildlife species. Violent ^^ 

 fluctuations in shoreline elevation and the resultant wide littoral zone create ^P 



84 



