Mitigation for the Construction and Operation of Libby Dam

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Libby Reservoir Zooplankton Monitoring Montana FWP has collected zooplankton from Libby Reservoir since 1983 in an attempt to relate changes in density and structure of the community to parameters of other aquatic communities, as well as to collect data indicative of reservoir processes, including aging and the effects of reservoir operation. We performed monthly vertical zooplankton tows using a 0.3 m, 153µ Wisconsin net in each of three reservoir areas (Tenmile, Rexford and Canada) from 1983 to 1996. However, beginning in 1997, we reduced sampling effort to the period April through November, after a rigorous analysis indicated we would not compromise our ability to identify trends (Hoffman et al. 2002). In an effort to further standardize sampling methodologies, we experimented with the effects of sample depth on the resulting analyses. When we excluded samples of greater than 20 m, the results were statistically similar (Kruska- Wallis p = 0.05; Hoffman et al. 2002) relative to analyses including depths of 30 m with regards to total zooplankton abundance. These results corroborate previous from Schindler trap sampling that found that approximately 90% of all zooplankton captured were from depths of 20 m or less (Skaar et al. 1996). Therefore, beginning in 1997, we conducted 20 m sampling tows when depth permitted, and when depth was between 10 and 20 m we sampled the entire water column. We did not collect samples when depth was less than 10 m. This differed from sampling protocols used from 1983 through 1989, where one sample was taken from a permanent station and two samples were taken randomly in each area, regardless of water depth. However, we made two sampling protocol changes that were implemented in 1990 that included the following. We only collected zooplankton samples when depth was at least 10 m, and all sampling locations (reservoir mile) and bank (east, west or middle) were randomly selected. All samples were pulled at a rate of 1 m/second to minimize backwash (Leathe and Graham 1982). Zooplankton samples were preserved in a water / methyl alcohol / formalin / acetic acid solution from September 1986 to November 1986. After December 1986, all samples were preserved in 95% ethyl alcohol to enhance egg retention in Cladocerans. Low density samples (
Results Bull Trout Redd Counts Grave Creek MFWP counted redds in the Grave Creek Basin (including Blue Sky, Clarence, Williams and Lewis Creeks) for the first time in 1983, as well as in 1984, 1985, and 1993 through 2003. Grave Creek was surveyed from its confluence with the Tobacco River upstream to near the mouth of Lewis Creek (approximately13 miles), where it becomes intermittent. Most redds in Grave Creek were located upstream from the mouth of Clarence Creek to the confluence with Lewis Creek. Surveyors found 10 redds between the confluence with the Tobacco River and one mile below Clarence Creek in 1983 However, we did not find redds in this reach during surveys conducted in 1993 and 2000. The distribution of bull trout redds in Blue Sky, Clarence, Williams and Lewis creeks was similar to observations in previous years (Hoffman et al. 2002). We observed 245 bull trout redds in Grave Creek in 2003, which was a record number for the period of record (Table 1). Bull trout have exhibited a significant positive trend in spawning abundance in Grave Creek since 1993 (Figure 2; r 2 = 0.794; p = 0.0002). 300 Bull Trout Redds 250 200 150 100 50 1993-2003 r 2 = 0.794 p = 0.0002 Y = -40584.7 + 20.36*X 0 1980 1985 1990 1995 2000 2005 Year Figure 2. Bull trout redd counts, and trend analysis in Grave Creek, 1993 through 2003. 52
Page 1 and 2: Mitigation for the Construction and
Page 3 and 4: MITIGATION FOR THE CONSTRUCTION AND
Page 5 and 6: depth of burbot that were relocated
Page 7 and 8: ACKNOWLEDGEMENTS We are thankful to
Page 9 and 10: Juvenile Salmonid Population Estima
Page 11 and 12: deviation from reference conditions
Page 13 and 14: Figure 46. Minimal detectible diffe
Page 15 and 16: Chapter 2 Tables Table 1. Design sp
Page 17 and 18: INTRODUCTION Libby Reservoir was cr
Page 19 and 20: PROJECT HISTORY Montana Fish, Wildl
Page 21 and 22: 2002 - Montana FWP collaborated wit
Page 23 and 24: DESCRIPTION OF STUDY AREA Subbasin
Page 25 and 26: Table 1. Current relative abundance
Page 27 and 28: Similar impacts have been observed
Page 29 and 30: 2460 2440 2420 2400 2380 2360 2340
Page 31 and 32: construction and operation of Libby
Page 33 and 34: 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 reduced again to 28 ganged floa
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 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
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Table 12. Individual probability va
Page 105 and 106:
Discussion Long-term monitoring of
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We believe that Libby Reservoir dur
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Figure 47. Minimal detectible diffe
Page 111 and 112:
References Bahls, L., R. Bukantis,
Page 113 and 114:
trout status report (below Kootenai
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Chapter 2 Stream Restoration and Mi
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food sources, as evidenced by the l
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Methods and Results Eureka Pond The
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spacing was 172.8 feet, which repre
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Figure 2. Vicinity Map for Upper Li
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Table 1. Design specifications for
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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
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190.0 185.0 180.0 175.0 170.0 165.0
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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
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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