Mitigation for the Construction and Operation of Libby Dam

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Libby Reservoir Gillnet Monitoring We documented changes in the assemblage of fish species sampled in Libby Reservoir since impoundment. Kokanee salmon, Kamloops rainbow trout and yellow perch did not occur in the Kootenai River prior to impoundment but are now present. Kokanee were released into the reservoir from the Kootenay Trout Hatchery in British Columbia (Huston et al. 1984). Yellow perch may have dispersed into the reservoir from Murphy Lake (Huston et al. 1984). The British Columbia Ministry of Environment (BCMOE) first introduced Kamloops rainbow trout in 1985. Eastern brook trout are not native to the Kootenai Drainage, but were present in the river before impoundment and continue to be rarely captured in gillnets within the reservoir. Peamouth and northern pikeminnow were rare in the Kootenai River before impoundment, but have increased in abundance in the reservoir. Mountain whitefish, rainbow trout, westslope cutthroat trout and redside shiner were common in the Kootenai River before impoundment, but have decreased in abundance since impoundment. Kokanee Since the accidental introduction of 250,000 fry from the Kootenay Trout Hatchery in British Columbia into Libby Reservoir in 1980, kokanee have become the second most abundant fish captured during fall gillnetting. Fluctuations in catch have corresponded to the strength of various year classes (Hoffman et al. 2002), and have varied by year, with no apparent continuous trend in abundance (Figure 32). However, kokanee catch in the fall net series follows a general trend of decreasing abundance from 1988-1995 and an increasing trend in abundance from 1996-2003 (Figure 32). Average length of kokanee has varied among years. Average length and weight between 1988 and 2003 was 290.3 mm and 235.2 g respectively (Table 6), while maximum average size occurred in 1992 (350 mm, 411 g). However, the minimum mean length was observed in 2002 (Table 6). Catch per Net 30 25 20 15 10 5 Spring r 2 = 0.008 p = 0.739 Fall (1988-1995) r 2 = 0.44;p = 0.073 Y = 3773 - 1.89*X Fall (1996-2003) r 2 = 0.44;p = 0.072 Y = -3964 + 1.99*X 0 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year Fall Floating Nets Spring Sinking Nets Figure 32. Average catch per net of kokanee for fall floating (1988-2003) and spring sinking (1984-2003) gill nets in Libby Reservoir. 91
Table 6. Average length and weight of kokanee salmon captured in fall floating gillnets (Tenmile and Rexford) in Libby Reservoir, 1988 through 2003. YEAR Sample size (n) Length (mm) Weight (gm) 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 AVG. 2150 1259 517 624 250 111 291 380 132 88 76 200 342 120 357 263 447.5 315.5 275 257.3 315.8 350 262.7 270.2 300.2 293.7 329.6 333.9 291.6 271.3 261.6 251.3 264.9 290.3 289.1 137.2 158.4 327.3 411.3 162.3 191.7 261.6 234.5 363.2 322.0 229.6 185.6 161.6 152.2 175.5 235.2 92
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Mitigation for the Construction and
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MITIGATION FOR THE CONSTRUCTION AND
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depth of burbot that were relocated
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ACKNOWLEDGEMENTS We are thankful to
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Juvenile Salmonid Population Estima
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deviation from reference conditions
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Figure 46. Minimal detectible diffe
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Chapter 2 Tables Table 1. Design sp
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INTRODUCTION Libby Reservoir was cr
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PROJECT HISTORY Montana Fish, Wildl
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2002 - Montana FWP collaborated wit
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DESCRIPTION OF STUDY AREA Subbasin
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Table 1. Current relative abundance
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Similar impacts have been observed
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2460 2440 2420 2400 2380 2360 2340
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construction and operation of Libby
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Chapter 1 Physical and Biological M
Page 35 and 36: Biological monitoring data was prov
Page 37 and 38: Figure 1. An aerial photograph of L
Page 39 and 40: antenna located approximately 5 cm
Page 41 and 42: We compared samples collected in Se
Page 43 and 44: extends downstream 131 m. This sect
Page 45 and 46: and reduced again to 28 ganged floa
Page 47 and 48: Results Bull Trout Redd Counts Grav
Page 49 and 50: Table 1. Bull trout redd survey sum
Page 51 and 52: Quartz Creek Bull trout redd counts
Page 53 and 54: Bull Trout Redds 40 35 30 25 20 15
Page 55 and 56: Keeler Creek Bull trout that spawn
Page 57 and 58: Burbot Monitoring Below Libby Dam T
Page 59 and 60: Table 2. Summary information for th
Page 61 and 62: 7000 6000 5000 Y = 45.246e 0.0055x
Page 63 and 64: The Libby FWP Mitigation Staff surg
Page 65 and 66: Table 2. (Continued) Capture locati
Page 67 and 68: Figure 18. Capture locations for a
Page 69 and 70: Table 4. T-test results. This table
Page 71 and 72: Figure 19. Montana Mountain Metrics
Page 73 and 74: Table 5. T-test results. This table
Page 75 and 76: Juvenile Salmonid Population Estima
Page 77 and 78: Grave Creek Juvenile salmonid monit
Page 79 and 80: Number Fish per 1000 Feet 100 80 60
Page 81 and 82: Libby Creek Section 1 of Libby Cree
Page 83 and 84: Figure 28. Rainbow trout, brook tro
Page 85: Pipe Creek Juvenile rainbow trout w
Page 89 and 90: Catch per Net A. Mountain Whitefish
Page 91 and 92: Table 8. Kamloops rainbow trout cap
Page 93 and 94: 25000.0 20000.0 15000.0 10000.0 500
Page 95 and 96: Burbot per Trap Day 3 2.5 2 1.5 1 0
Page 97 and 98: Table 9. Average catch per net for
Page 99 and 100: Table 11. Percent composition of ma
Page 101 and 102: deviation = 0.052; Figure 43), with
Page 103 and 104: Table 12. Individual probability va
Page 105 and 106: Discussion Long-term monitoring of
Page 107 and 108: We believe that Libby Reservoir dur
Page 109 and 110: Figure 47. Minimal detectible diffe
Page 111 and 112: References Bahls, L., R. Bukantis,
Page 113 and 114: trout status report (below Kootenai
Page 115 and 116: Chapter 2 Stream Restoration and Mi
Page 117 and 118: food sources, as evidenced by the l
Page 119 and 120: Methods and Results Eureka Pond The
Page 121 and 122: spacing was 172.8 feet, which repre
Page 123 and 124: Figure 2. Vicinity Map for Upper Li
Page 125 and 126: Table 1. Design specifications for
Page 127 and 128: 70 60 50 40 30 20 10 0 500 1000 150
Page 129 and 130: Grave Creek Phase I Restoration Pro
Page 131 and 132: Table 4. Design specifications for
Page 133 and 134: 190.0 185.0 180.0 175.0 170.0 165.0
Page 135 and 136: educed the mean width and width to
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Table 7. Mean cross sectional area,
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Discussion The Grave Creek Phase I
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References Chisholm, I.M., M.E. Hen
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Appendix 148
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Table A2. Lower Grave Creek Demonst
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Table A4. Libby Creek depletion pop
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Table A7. Mean zooplankton densitie
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Table A9. Mean zooplankton densitie
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Table A13. Yearly mean total zoopla
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Mitigation for the Construction and Operation of Libby Dam

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