Mitigation for the Construction and Operation of Libby Dam

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iological production during warm months. Annual drawdowns impede revegetation of the reservoir varial zone and result in a littoral zone of nondescript cobble/mud/sand bottom with limited habitat structure. Table 2. Morphometric data for Libby Reservoir. Surface elevation maximum pool minimum operational pool minimum pool (dead storage) 749.5 m (2,459 ft) 697.1 m (2,287 ft) 671.2 m (2,222 ft) Area maximum pool minimum operational pool 188 sq. km (46,500 acres) 58.6 sq. km (14,487 acres) Volume maximum pool minimum operational pool Maximum length Maximum depth Mean depth Shoreline length Shoreline development Storage ratio Drainage area 7.24 km 3 (5,869,400 acre-ft) 1.10 km 3 (890,000 acre-ft) 145 km (90 mi) 107 m (350 ft) 38 m (126 ft) 360 km (224 mi) 7.4 km (4.6 mi) 0.68 yr 23,271 sq. km (8,985 sq. mi) Drainage area:surface area 124:1 Average daily discharge pre-dam (1911-1972) post-dam (1974-2000) 11,774 cfs 10,991 cfs 24
Similar impacts have been observed in the tailwater below Libby Dam. The zone of water fluctuation or varial zone has been enlarged by daily changes in water-flow and stage caused by power operations. The resulting rapid fluctuations in dam discharges (as great as 400 percent) are inconsistent with the normative river concept (ISAB 1997). The varial zone is neither a terrestrial nor aquatic environment, so is biologically unproductive. Daily and weekly differences in discharge from Libby Dam have an enormous impact on the stability of the riverbanks. Water logged banks are heavy and unstable; when the flow drops in magnitude, banks calve off, causing serious erosion in the riparian zone. These impacts are common during winter but go unnoticed until spring. In addition, widely fluctuating flows can give false migration cues to burbot and white sturgeon spawners (Paragamian 2000 and Paragamian and Kruse 2001). Also, barriers have been deposited in critical spawning tributaries to the Kootenai River through the annual deposition of bedload materials (sand, gravel, and boulders) at their confluence with the river (Marotz et al. 1988). During periods of low stream flow, the enlarged deltas and excessive deposition of bedload substrate in the low gradient reaches of tributaries impedes or blocks fall-spawning migrations. During late spring and summer, when redband and cutthroat trout are out-migrating from nursery streams, the streams may flow subsurface through the porous deltas (Paragamian V., IDFG, personal communication 2000). As a result, many potential recruits are stranded. Prior to impoundment, the Kootenai River contained sufficient hydraulic energy to annually remove these deltas, but since the dam was installed, peak flows have been limited to maximum turbine capacity (roughly 27 kcfs). Hydraulic energy is now insufficient to remove deltaic deposits. Changing and regulating the Kootenai River annual hydrograph for power and flood control and altering the annual temperature regime have caused impacts typical of dam tailwaters. 25
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: Table 1. Current relative abundance
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 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 and 86:
Pipe Creek Juvenile rainbow trout w
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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
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25000.0 20000.0 15000.0 10000.0 500
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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
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food sources, as evidenced by the l
Page 119 and 120:
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
Page 125 and 126:
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
Page 141 and 142:
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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