Mitigation for the Construction and Operation of Libby Dam

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1.6 1.4 Mean Length (mm) 1.2 1.0 0.8 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 0.6 Figure 44. Mean length of Daphnia species in Libby Reservoir, 1984 through 2003, with 95% confidence intervals. 109
Discussion Long-term monitoring of bull trout redd numbers can be an important tool to assess bull trout population trends (Rieman & McIntyre 1993). Bull trout redd counts in the tributaries that we monitor below Libby Dam have not increased in proportion to the increases we have observed in redd counts in bull trout spawning tributaries located upstream of Libby Dam over the past 9 years. We are however, confident that we have identified the important core spawning tributaries below Libby Dam within the Montana portion of the basin. Although drought conditions in 2001 through 2003 likely exacerbated the effects of debris jams in some of these streams by forming impassible and substantial barriers in some of the tributaries may have reduced redd counts, the bull trout redd count information does not correlate well with our adult bull trout population estimate conducted in the spring of 2004 below Libby Dam. We observed a total of 126 bull trout redds in Quartz, Pipe, O’Brien, and Bear Creeks in the fall of 2003. Baxter and Westover (2000) estimated an average of 1.55 fish per redd (range = 1.2-2.1 fish per redd) for spawning bull trout in the Wigwam River in 1996-1999. If we apply these ratios to bull trout redd counts in the 4 spawning tributaries below Libby Dam 2003 (Table 1; 126 total redds), there may have been 195 (range 150 – 265) spawning bull trout in the Kootenai River below Libby Dam in 2003. We estimated a total of 920 bull trout (95% confidence interval 698 – 1142). We believe most of these fish were likely adult fish. Baxter and Baxter (2002) operated a fish trap on Skookumchuck Creek in 2001 and estimated the mean size of spawning adults to be 640 mm (range 400-920 mm), which was similar to the size of fish we found below Libby Dam during our spring 2004 population estimate (mean total length 649 mm; range 343 – 861 mm). Although we acknowledge that the 2003 bull trout redd counts within the tributaries below Libby Dam may have underestimated of the total Kootenai River bull trout population because they did not take into account alternate year spawning individuals, the disparity between our adult population estimate and the redd count data is nevertheless large. One possible explanation for these large differences may bull trout entrainment through Libby Dam from within Libby Reservoir. The bull trout redd counts, juvenile estimates and adult bull trout estimates collected by Montana FWP provide critical information required to assess the status and trends of bull trout within the Kootenai River Basin. This information will be essential to determine whether recovery criteria (USFWS 2002) are met within this basin. Therefore, collection of these data will remain a high priority for long-term monitoring conducted by Montana FWP. This project will also investigate the use of other methodologies, such as scale and otolith micro-chemistry (Wells et al. 2000; Wells et al. 2003; Kennedy et al. 2000) to determine the origin of adult bull trout below Libby Dam. Catch rates of burbot in our baited hoopnets in the Kootenai River directly below Libby Dam have precipitously and significantly decreased in recent years. Our burbot catch rates using baited hoop traps in the stilling basin below Libby Dam were the lowest since we began monitoring this site in 1994/1995, and averaged only 0.0139 burbot per trap day, or one burbot every 72 trap-days during the 2003/2004 trapping season. In comparison, our catch rates for burbot using similar gear and techniques in Libby Reservoir during the same period were approximately 5 times higher. However, since this was the first year of trapping burbot in Libby Reservoir, using techniques similar to those we use in 110
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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
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Biological monitoring data was prov
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Figure 1. An aerial photograph of L
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antenna located approximately 5 cm
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We compared samples collected in Se
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extends downstream 131 m. This sect
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and reduced again to 28 ganged floa
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Results Bull Trout Redd Counts Grav
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Table 1. Bull trout redd survey sum
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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 and 86: Pipe Creek Juvenile rainbow trout w
Page 87 and 88: Table 6. Average length and weight
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: Table 12. Individual probability va
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
Page 137 and 138: Table 7. Mean cross sectional area,
Page 139 and 140: Discussion The Grave Creek Phase I
Page 141 and 142: References Chisholm, I.M., M.E. Hen
Page 143 and 144: Appendix 148
Page 145 and 146: Table A2. Lower Grave Creek Demonst
Page 147 and 148: Table A4. Libby Creek depletion pop
Page 149 and 150: Table A7. Mean zooplankton densitie
Page 151 and 152: Table A9. Mean zooplankton densitie
Page 153: Table A13. Yearly mean total zoopla
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Mitigation for the Construction and Operation of Libby Dam

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