IV. RESULTS 



A. HABITAT 



At full pool, Lake Koocanusa inundates 28,850 acres of habitat 

 within the United States. During periods of reservoir drawdown, a 

 portion of this acreage is exposed; however, the fluctuating water 

 levels are not conducive to the establishment of vegetation within 

 this zone. Therefore a total loss of the 28,850 acres was assumed. 

 The inundated habitats are summarized in Table 1. Maps illustrating 

 the extent of the habitats are on file in the Regional Office, 

 Montana Department of Fish, Wildlife and Parks, Kalispell, Montana. 

 In addition, copies of the maps will be sent to all cooperating 

 entities. 



The 28,850 acres of inundated habitats included 3,314 acres of 

 aquatic habitat and 25,536 acres of terrestrial habitat (island, 

 valley floor, and upland). The 3,314 acres of aquatic habitat was 

 11.5 percent of the inundated area and consisted of 52.5 miles of 

 riverine habitat (48.4 miles of the Kootenai River and 4.1 miles of 

 the Tobacco River), 48.8 miles of tributary streams and several 

 bodies of standing water. These areas of open water were usually 

 bordered by one or more types of riparian habitat, forming aquatic/ 

 terrestrial ecotones. This combination of habitats has been shown 

 to be very important in the maintenance of an abundant and diverse 

 wildlife community (Carothers 1977, Thomas et al. 1980). In addi- 

 tion, islands were found along the entire portion of the river 

 inundated by the reservoir; however, they were more common in the 

 reach from the original townsite of Rexford north to border. A 

 total of 47 islands (23 vegetated and 24 gravel bars) were found 

 within the inundated portion of the river. Of these, 16 of the 

 vegetated islands (69.5 percent) were located upstream from the 

 original townsite of Rexford, while 14 of the gravel bars (58.3 

 percent) were found within this reach. The remaining islands were 

 distributed throughout the segment of the river from the townsite 

 to the dam site. Replacement of these habitats with a large body 

 of open water lacking well established riparian vegetation resulted 

 in an adverse impact to the diverse wildlife community occupying 

 the riparian habitats. 



A variety of terrestrial habitats were inundated by Lake 

 Koocanusa. Riparian habitat types totaled 5,006 acres, 17.3 per- 

 cent of the inundated area (19.6 percent of the terrestrial habi- 

 tats). These habitats supported diverse and abundant wildlife 

 communities and provided important components of various big game 

 seasonal ranges. The variety of vegetational structural components 

 within these habitat t^/pes provided a diversity of reproductive and 

 foraging habitat for many nongame wildlife species not specifically 

 addressed v/ichin this assessment. Non-timbered upland habitats - 

 sub-irrigated grasslands, grasslands, arid upland shrub - comprised 

 5,146 acres, 17.8 percent of the inundated area (20.2 percent of 



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