Snake River White Sturgeon Conservation Plan

Idaho Power Company

July 2003

Idaho Power Company Snake River White Sturgeon Conservation Plan

TABLE OF CONTENTS

List of Tables ...... vii

List of Figures...... viii

List of Appendices ...... xiv

Executive Summary...... 1

1. Introduction...... 3

2. Biology of White Sturgeon ...... 4

2.1. Description...... 4

2.2. Sexual Maturity...... 5

2.3. Spawning...... 6

2.4. Incubation ...... 6

2.5. Larvae ...... 7

2.6. Young-of-Year...... 8

2.7. Juveniles and Adults ...... 8

2.8. Movement ...... 9

3. Anthropogenic Impacts to White Sturgeon...... 12

3.1. Dams and Reservoirs ...... 12

3.2. Flow Regulation...... 13

3.3. Water Quality...... 15

3.3.1. Dissolved Oxygen...... 16

3.3.2. Temperature ...... 18

3.3.3. Contaminants ...... 19

3.3.4. Total Dissolved Gas...... 20

3.4. Genetics...... 22

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3.5. Exploitation...... 24

4. Status of Snake River White Sturgeon...... 25

4.1. Shoshone Falls–Upper Salmon Falls Reach ...... 25

4.1.1. Project and Reach Description...... 25

4.1.2. Population Status ...... 26

4.2. Upper Salmon Falls–Lower Salmon Falls Reach ...... 29

4.2.1. Project and Reach Description...... 29

4.2.2. Population Status ...... 29

4.3. Lower Salmon Falls–Bliss Reach ...... 30

4.3.1. Project and Reach Description...... 30

4.3.2. Population Status ...... 30

4.4. Bliss–C.J. Strike Reach...... 32

4.4.1. Project and Reach Description...... 32

4.4.2. Population Status ...... 33

4.5. C.J. Strike–Swan Falls Reach ...... 34

4.5.1. Project and Reach Description...... 34

4.5.2. Population Status ...... 35

4.6. Swan Falls–Brownlee Reach ...... 37

4.6.1. Project and Reach Description...... 37

4.6.2. Population Status ...... 38

4.7. Brownlee–Oxbow Reach ...... 41

4.7.1. Project and Reach Description...... 41

4.7.2. Population Status ...... 41

4.8. Oxbow–Hells Canyon Reach...... 42

4.8.1. Project and Reach Description...... 42

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4.8.2. Population Status ...... 42

4.9. Hells Canyon–Lower Granite Reach ...... 43

4.9.1. Project and Reach Description...... 43

4.9.2. Population Status ...... 44

5. Population Viability Analysis...... 45

6. Goal and Targets...... 47

6.1. Goal...... 47

6.2. Targets...... 48

7. Recommended Measures by WSTAC ...... 49

7.1. Shoshone Falls–Upper Salmon Falls Reach ...... 49

7.2. Upper Salmon Falls–Lower Salmon Falls Reach ...... 50

7.3. Lower Salmon Falls–Bliss Reach ...... 50

7.4. Bliss–C.J. Strike Reach...... 51

7.5. C.J. Strike–Swan Falls Reach ...... 51

7.6. Swan Falls–Brownlee Reach ...... 52

7.7. Brownlee–Hells Canyon Reach ...... 52

7.8. Hells Canyon–Lower Granite Reach ...... 53

7.9. Recommended Measures Not Specific to White Sturgeon...... 54

8. Measures Proposed by IPC ...... 54

8.1. Shoshone Falls–Upper Salmon Falls Reach ...... 55

8.1.1. Monitor Spawning and Early Life Stage Survival...... 55

8.1.2. Develop Experimental Conservation Aquaculture Program...... 57

8.1.3. Conduct Periodic Population Assessments...... 59

8.1.4. Monitor Genotypic Frequencies ...... 60

8.1.5. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects ...... 62

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8.1.6. Develop Schematic Diagram of Proposed Mitigation Measures...... 63

8.2. Upper Salmon Falls–Lower Salmon Falls Reach ...... 63

8.2.1. Conduct Periodic Population Assessments...... 63

8.2.2. Monitor Genotypic Frequencies ...... 64

8.2.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects ...... 64

8.2.4. Develop Schematic Diagram of Proposed Mitigation Measures...... 64

8.3. Lower Salmon Falls–Bliss Reach ...... 64

8.3.1. Conduct Periodic Population Assessments...... 64

8.3.2. Monitor Genotypic Frequencies ...... 65

8.3.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects ...... 66

8.3.4. Develop Schematic Flow Chart for PM&E Measures...... 66

8.4. Bliss–C.J. Strike Reach...... 66

8.4.1. Conduct Periodic Population Assessments...... 66

8.4.2. Monitor Genotypic Frequencies ...... 67

8.4.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects ...... 67

8.4.4. Improve Water Quality in C.J. Strike Reservoir by Developing Specific Measures through the C.J. Strike TMDL...... 68

8.4.5. Develop Schematic Diagram of Proposed Mitigation Measures...... 68

8.5. C.J. Strike–Swan Falls Reach ...... 68

8.5.1. Translocate Reproductive-Sized Adults below C.J. Strike Dam to Spawning Habitat in the Bliss–C.J. Strike Reach...... 68

8.5.2. Determine Feasibility of Developing Spawning and Incubation Habitats...... 71

8.5.3. Determine Feasibility of Reducing Trash Bar Spacing ...... 72

8.5.4. Conduct Periodic Population Assessments...... 75

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8.5.5. Monitor Genotypic Frequencies ...... 76

8.5.6. Evaluate Effects of Angling below C.J. Strike Dam ...... 76

8.5.7. Improve Water Quality in C.J. Strike Reservoir by Developing Specific Measures through the C.J. Strike TMDL...... 77

8.5.8. Develop Schematic Diagram of Proposed Mitigation Measures...... 77

8.6. Swan Falls–Brownlee Reach ...... 77

8.6.1. Assess Water Quality-Related Impacts on Early Life Stages...... 77

8.6.2. Improve Dissolved Oxygen Conditions in Brownlee Reservoir...... 80

8.6.3. Translocate Reproductive-Sized White Sturgeon to Increase Spawner Abundance and Population Productivity ...... 80

8.6.4. Develop Experimental Conservation Aquaculture Plan ...... 82

8.6.5. Conduct Periodic Population Assessments...... 84

8.6.6. Monitor Genotypic Frequencies ...... 85

8.6.7. Develop Schematic Diagram of Proposed Mitigation Measures...... 85

8.7. Brownlee–Hells Canyon Reach (Oxbow and Hells Canyon Reservoirs)...... 85

8.7.1. Improve Dissolved Oxygen and Total Dissolved Gas Conditions in Oxbow and Hells Canyon Reservoirs...... 85

8.7.2. Conduct Periodic Population Assessments...... 85

8.7.3. Monitor Genotypic Frequencies ...... 86

8.7.4. Develop Schematic Diagram of Proposed Mitigation Measures...... 86

8.8. Hells Canyon–Lower Granite Reach ...... 86

8.8.1. Improve Dissolved Oxygen and Total Dissolved Gas Conditions below Hells Canyon Dam...... 86

8.8.2. Conduct Periodic Population Assessments...... 87

8.8.3. Monitor Genotypic Frequencies ...... 88

8.8.4. Develop Schematic Diagram of Proposed Mitigation Measures...... 88

9. Explanation for Rejection of any WSTAC Recommendations by IPC ...... 88

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9.1. Shoshone Falls–Upper Salmon Falls Reach ...... 88

9.2. Upper Salmon Falls–Lower Salmon Falls Reach ...... 90

9.3. Lower Salmon Falls–Bliss Reach ...... 91

9.4. Bliss–C.J. Strike Reach...... 92

9.5. C.J. Strike–Swan Falls Reach ...... 93

9.6. Swan Falls–Brownlee Reach ...... 95

9.7. Brownlee–Hells Canyon Reach ...... 97

9.8 Hells Canyon–Lower Granite Reach ...... 100

9.9. Recommended Measures Not Specific to White Sturgeon...... 100

10. Literature Cited ...... 101

11. Tables...... 117

12. Figures...... 133

13. Appendices...... 201

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LIST OF TABLES

Table 1. Years that hydroelectric projects on the Snake River went into operation...... 119

Table 2. Summary of storage facilities upstream of Hells Canyon Dam. (Source: Miller et al. 2002)...... 120

Table 3. List of water quality impaired segments for the Snake River that exceed Idaho state water quality standards or do not support their designated beneficial uses. (Source: IDEQ 1998, USEPA 2001)...... 122

Table 4. List of water quality impaired segments in the Snake River that exceed Oregon state water quality standards or do not support their designated beneficial uses...... 123

Table 5. Within-location white sturgeon haplotype frequency and haplotype and sequence diversity in western North America. (Source: Anders and Powell 2002)...... 124

Table 6. Summary of effort and catch for white sturgeon sampled by Idaho Power Company in the Snake River between Shoshone Falls and the mouth of the Salmon River...... 125

Table 7. Abundance estimates for white sturgeon populations in Snake River reaches between Shoshone Falls and Lower Granite dams...... 126

Table 8. Mean relative weights based on fork length measurements for white sturgeon populations in the Snake River between Shoshone Falls and Lower Granite dams...... 127

Table 9. Total annual mortality (A) and survival (S) estimates for white sturgeon sampled in the Snake River between Shoshone Falls and Lower Granite dams...... 128

Table 10. Record of white sturgeon stocked by Idaho Department of Fish and Game and the Nez Perce Tribe in the Snake River...... 129

Table 11. Mean hourly weighted usable area (WUA) under Proposed Operations as a percent of WUA under Run-of-River Full Pool Operations hourly-WUA (HWUA) in the Hells Canyon Reach for white sturgeon life stages during the extreme low (1992), low (1994), medium (1995), high (1999), and extreme high (1997) flow years. The HWUA decreased metric is a mean of the 50–100% exceedence range of HWUA and the HWUA increased metric is a mean of the 0–50% exceedence range of HWUA. (Source: Chandler et al. 2002)...... 130

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Table 12. Cost estimates of IPC proposed mitigation measures for Snake River white sturgeon by hydroelectric project...... 131

LIST OF FIGURES

Figure 1. Map of Snake River segments surveyed by Idaho Power Company for white sturgeon from Shoshone Falls downstream to the mouth of the Salmon River. The years indicate the time period during which each segment was surveyed...... 135

Figure 2. Range of total lengths, by reproductive category, for female white sturgeon sampled in the Snake River by Idaho Power Company, 1991−2000...... 136

Figure 3. Estimated periods for spawning to age-0 life stages of Snake River white sturgeon. The occurrence of various life stage intervals was calculated based on the initiation of spawning using median Julian dates associated with lower (10 °C) and upper (18 °C) water temperature limits suitable for spawning in Snake River reaches, 1990–2000, and on embryonic development by Wang et al. (1985). The shaded portions of bars represent peak occurrence of the various life stages given peak spawning activity expected between 12 and 16 °C (based on egg collections in the Snake River) and subsequent embryonic development...... 137

Figure 4. Mean movement of and maximum recorded distance traveled by white sturgeon from their initial capture locations in Snake River reaches between Bliss Dam and the confluence with the Salmon River. Data from Idaho Power Company...... 138

Figure 5. Map of the Columbia River basin showing major dams on the mainstem Columbia and Snake rivers...... 139

Figure 6. Average monthly natural flow and observed flow of the Snake River at Milner and the Boise River near Parma gauges. (Source: Miller et al. 2002)...... 140

Figure 7. Mean daily flow and water temperature in four reaches of the Snake River during the white sturgeon spawning season in 1996...... 141

Figure 8. Map of the Snake River from Shoshone Falls Dam to Upper Salmon Falls Dam...... 142

Figure 9. Annual contribution of water to the Snake River from springs along the north bank of the Snake River between Milner Dam and King Hill (from Clark et al. 1998). Numbers above bars represent percentages of annual streamflow...... 143

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Figure 10. Catch rates of and hours of effort expended for white sturgeon sampled with setlines in the Snake River between Shoshone Falls and the confluence of the Salmon River...... 144

Figure 11. Catch rates of and hours of effort expended for white sturgeon sampled with gill nets in the Snake River between Shoshone Falls and Hells Canyon Dam...... 145

Figure 12. Size distributions of white sturgeon sampled with setlines (adjusted for gear selectivity) in the Snake River between Shoshone Falls and Lower Granite Dam. Data below Hells Canyon Dam combined with the data from Nez Perce Tribe sturgeon surveys...... 146

Figure 13. Size distributions of white sturgeon sampled with gill nets (adjusted for gear selectivity) in the Snake River between Shoshone Falls and Brownlee Dam...... 147

Figure 14. Length–weight relationships for white sturgeon in Snake River reaches between Shoshone Falls and Lower Granite Dam...... 148

Figure 15. Annual in-river growth (length and weight) of hatchery-propagated white sturgeon in the Snake River between Shoshone Falls and Upper Salmon Falls Dam. Data obtained from Lepla et al. (2002)...... 149

Figure 16. Von Bertalanffy growth (VBG) lines and mean total length (Shoshone Falls–Upper Salmon Falls reach) for white sturgeon in the Snake River between Shoshone Falls and Lower Granite Dam...... 150

Figure 17. Size composition of white sturgeon sampled in the Snake River between Shoshone Falls and Upper Salmon Falls Dam during the 1980–1981 period (Lukens 1981) and in 2001 (Lepla et al. 2002)...... 151

Figure 18. Percentage of exceedence of river flow for the periods of record during spawning, incubation, and larval life stages of development (March–June) for Snake River white sturgeon between Shoshone Falls and Upper Salmon Falls Dam. River flows measured at USGS flow gauges in the Snake River near Kimberly and Buhl, Idaho...... 152

Figure 19. Map of the Snake River from Upper Salmon Falls Plant B downstream to Bliss Dam...... 153

Figure 20. Size composition of white sturgeon sampled in the Lower Salmon Falls– Bliss reach...... 154

Figure 21. Minimum daily Weighted Usable Area (MDW) expressed as a percent of run-of-river WUA (left) and percent time exceeded for hourly WUA (HW) as a percent of run-of-river WUA (right) for white sturgeon spawning, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000)...... 155

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Figure 22. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for juvenile white sturgeon, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000)...... 156

Figure 23. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for adult white sturgeon, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000)...... 157

Figure 24. Map of the Bliss–C.J. Strike reach of the Snake River...... 158

Figure 25. Annual growth of recaptured white sturgeon in the Bliss–C.J. Strike reach of the Snake River...... 159

Figure 26. Size composition of white sturgeon sampled in the Bliss–C.J. Strike reach of the Snake River...... 160

Figure 27. Annual flow in the Snake River as measured below Bliss Dam at King Hill, Idaho...... 161

Figure 28. Estimated age distribution of white sturgeon collected in the Bliss– C.J. Strike reach of the Snake River during 2000...... 162

Figure 29. Hourly river flows below Bliss Dam during the white sturgeon spawning season for 1988 through 1994...... 163

Figure 30. Minimum daily Weighted Usable Area (MDW) expressed as a percent of run-of-river WUA (left) and percent time exceeded for hourly WUA (HW) as a percent of run-of-river WUA (right) for white sturgeon spawning, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 164

Figure 31. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for white sturgeon incubating eggs, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 165

Figure 32. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for white sturgeon larvae, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 166

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Figure 33. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for young-of-year white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 167

Figure 34. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for juvenile white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 168

Figure 35. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for adult white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000)...... 169

Figure 36. Map of the C.J. Strike–Swan Falls reach of the Snake River from C.J. Strike Dam to Swan Falls Dam...... 170

Figure 37. Size composition of white sturgeon sampled in the C.J. Strike–Swan Falls reach of the Snake River...... 171

Figure 38. Weighted Usable Area and WUA (ft2) as a percentage of total area for white sturgeon spawning in the tailrace of C.J. Strike Dam. (Source: Chandler and Lepla 1997)...... 172

Figure 39. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997)...... 173

Figure 40. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997)...... 174

Figure 41. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997)...... 175

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Figure 42. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997)...... 176

Figure 43. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997)...... 177

Figure 44. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997)...... 178

Figure 45. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997)...... 179

Figure 46. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997)...... 180

Figure 47. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997)...... 181

Figure 48. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997)...... 182

Figure 49. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997)...... 183

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Figure 50. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997)...... 184

Figure 51. Size distributions of white sturgeon sampled with setlines in the C.J. Strike–Swan Falls reach of the Snake River during 1994–1996 and in 2001...... 185

Figure 52. Daily weighted usable area (WUA) expressed as minimum daily percentage of run-of-river WUA and percentage-exceeded curve for minimum daily percentage of run-of-river WUA for the white sturgeon spawning periods during 1996 to 1999 below C.J. Strike Dam...... 186

Figure 53. Map of the Swan Falls–Brownlee reach of the Snake River...... 187

Figure 54. Size composition of white sturgeon sampled in the Swan Falls–Brownlee reach of the Snake River...... 188

Figure 55. Dissolved oxygen (DO) isopleths for Brownlee Reservoir representing low (1992), medium (1995) and high (1997) hydrologic years. (Source: Myers et al. 2001)...... 189

Figure 56. Map of the Brownlee–Hells Canyon reach of the Snake River...... 190

Figure 57. Size composition of white sturgeon sampled in the Oxbow–Hells Canyon reach of the Snake River...... 191

Figure 58. White sturgeon spawning habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow Bypass (transects 1−8). (Source: Myers and Chandler 2001)...... 192

Figure 59. White sturgeon incubation habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow Bypass (transects 1– 8). (Source: Myers and Chandler 2001)...... 193

Figure 60. White sturgeon spawning habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow tailwater (transects 9–11). (Source: Myers and Chandler 2001)...... 194

Figure 61. White sturgeon incubation habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow tailwater (transects 9–11). (Source: Myers and Chandler 2001)...... 195

Figure 62. Map of the Hells Canyon–Lower Granite reach of the Snake River...... 196

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Figure 63. Size composition of white sturgeon sampled in the Hells Canyon–Lower Granite reach of the Snake River...... 197

Figure 64. Schematic diagram of IPC proposed mitigation measures for Snake River white sturgeon between Shoshone Falls and C.J. Strike dams...... 199

Figure 65. Schematic diagram of IPC proposed mitigation measures for Snake River white sturgeon between C.J. Strike and Lower Granite dams...... 200

LIST OF APPENDICES

Appendix 1. Population Viability Model for Snake River White Sturgeon...... 203

Appendix 2. Conceptual Protection, Mitigation, and Enhancement Measures for Snake River white sturgeon...... 249

Appendix 3. White Sturgeon Technical Advisory Committee comments to the draft Snake River White Sturgeon Conservation Plan...... 273

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EXECUTIVE SUMMARY

White sturgeon, Acipenser transmontanus, in the Snake River have been classified by the state of Idaho as a species of special concern. Of the nine isolated subpopulations in the Snake River in Idaho, only the Hells Canyon–Lower Granite and the Bliss–C.J. Strike reaches currently support viable populations. The middle reaches of the Snake River between Hells Canyon and Swan Falls dams, as well as reaches upstream of Bliss Dam to Shoshone Falls (a natural barrier), contain only small populations and show little or no detectable recruitment. Factors that have played a role in sturgeon decline in other river systems—altered habitat, pollution, historical exploitation, and fragmentation—have also contributed to the current status of sturgeon in the Snake River.

Concern about the status, viability, and persistence of Snake River white sturgeon has been expressed by federal and state management agencies, Native American tribes, and nongovernmental organizations participating in the relicensing process for Idaho Power Company’s (IPC) hydroelectric projects. A White Sturgeon Technical Advisory Committee (WSTAC) was established in 1991 to provide technical guidance for research activities undertaken by IPC during its relicensing efforts. During this time, information presented at WSTAC meetings included 1) status surveys of Snake River sturgeon populations, 2) limiting factors for each reach, and 3) modeled results of the population viability analysis specific to reaches of the Snake River. This information formed the basis upon which the WSTAC developed recommendations for IPC to include in the Snake River White Sturgeon Conservation Plan (WSCP) and submit to the Federal Energy Regulatory Commission (FERC).

The WSCP is intended to serve as a master plan for guiding the implementation of feasible mitigation measures for Snake River white sturgeon populations impacted by IPC’s hydroelectric projects. These measures are designed to help ensure the species’ long-term persistence and restore opportunities for beneficial use. This plan outlines proposed measures and strategies for Snake River white sturgeon that IPC would implement once the WSCP were accepted and new project licenses issued by FERC.

The long life span of white sturgeon requires a long-term perspective in planning and commitment to sturgeon management. A guiding principle in the development of this WSCP is that mitigation actions to restore sturgeon populations in depressed reaches must not place existing viable sturgeon populations at risk. Sturgeon populations below Bliss and Hells Canyon dams currently exhibit self-sustaining natural recruitment and are considered genetically diverse. Because of these conditions, mitigation actions undertaken in the various reaches of the Snake River should not threaten the persistence and viability of these two remaining wild sturgeon populations.

The long-term goal, as defined in the WSCP, is to mitigate for IPC project-related impacts in order to provide for healthy populations of white sturgeon in each reach of the Snake River between the mouth of the Salmon River and Shoshone Falls, not including the reach between Upper Salmon Falls and Lower Salmon Falls dams. Achieving healthy sturgeon populations in each reach of the Snake River within the anticipated term (approximately 30 years) of new

1 Snake River White Sturgeon Conservation Plan Idaho Power Company hydroelectric project licenses is unlikely or impossible, given current population numbers and the extent of habitat degradation and alteration to the Snake River ecosystem. Therefore, this goal is considered “long term” and likely beyond the anticipated term of the new project licenses.

However, short-term objectives are necessary to guide mitigation actions within the time frame of new hydroelectric project licenses. The short-term objectives are to maintain and/or enhance population viability and persistence of white sturgeon below Bliss and Hells Canyon dams and, where feasible, begin to reestablish recruitment to populations where natural recruitment is severely limited. Population targets include population densities of 32 fish/km of usable habitat; naturally produced recruitment to support the desired population structure (60% of the individuals between 60 and 90 cm TL, 30% between 90 and 180 cm TL, and 10% greater than 180 cm TL) of juveniles and adults; stable or increasing trends in juvenile and adult numbers; and genetic diversity similar to current levels.

Effective implementation of the WSCP would require continuing adaptation based on research and monitoring of sturgeon status, limiting factors, and population responses to potential mitigation measures. This WSCP should not be viewed as a management plan, nor is it intended to replace existing management plans for Snake River white sturgeon. IPC recognizes the jurisdiction and management and protection responsibilities of state and federal fish and wildlife agencies and Native American tribes.

2 Idaho Power Company Snake River White Sturgeon Conservation Plan

1. INTRODUCTION

White sturgeon, Acipenser transmontanus, are the largest, longest-lived freshwater or anadromous fish in North America (Scott and Crossman 1973) and are highly adapted to the large river systems in which they evolved. Their large size and opportunistic behavior allowed them to range widely to take advantage of scattered and seasonally available resources in these dynamic river habitats and in the ocean. Longevity and high fecundity allowed them to persist through changes in their environment and to capitalize on favorable spawning conditions when they occurred (UCWSRI 2002). However, these population attributes that have proven adaptive for millions of years are now a liability. While large size and high fecundity make sturgeon a valuable fishery commodity, their longevity and delayed maturation make them extremely vulnerable to overfishing (Beamesderfer and Farr 1997). Long life span and benthic feeding also make sturgeon susceptible to bioaccumulation of pollutants with potentially detrimental effects on health, growth, maturation, and recruitment.

In addition, critical habitats have been altered. The construction of dams has blocked movements and restricted sturgeon to river fragments that may no longer provide the full spectrum of habitats necessary for white sturgeon to complete their life cycle. Flow regulation has altered seasonal and annual fluctuations that provide behavioral cues and suitable spawning or rearing conditions (UCWSRI 2002). As a result, sturgeon species are at risk (depleted, threatened, or extinct) almost everywhere they occur in temperate river systems of North America, Europe, and Asia (Smith 1990, Birstein 1993, UCWSRI 2002).

In the Snake River, white sturgeon have been classified by the state of Idaho as a species of special concern (Mosley and Groves 1990). Factors that have played a role in sturgeon decline in other river systems—altered habitat, pollution, historical exploitation, and population fragmentation by dams—have also contributed to the current status of sturgeon in the Snake River (Table 1). Of the nine isolated subpopulations in the Snake River in Idaho, only the Hells Canyon–Lower Granite and the Bliss–C.J. Strike reaches1 support viable populations (Cochnauer et al. 1985). In these reaches, abundance and population structure appear to be recovering from the impact of catch-and-keep fishing regulations prior to 1972. The sturgeon in these reaches appear to be well adapted to isolated conditions (Cochnauer 2002). However, Snake River reaches with small populations and little or no detectable natural recruitment occupy sections of river between Hells Canyon and Swans Falls dams and upstream of Bliss Dam.

Concern about the status, viability, and persistence of Snake River white sturgeon has been expressed by federal and state management agencies, Native American tribes, and nongovernmental organizations participating in the relicensing process for several of Idaho Power Company’s (IPC) hydroelectric projects. The White Sturgeon Technical Advisory Committee (WSTAC) was established in 1991 to provide technical guidance with white sturgeon research activities undertaken by IPC during its relicensing efforts. Since its formation,

1 Reaches used in this document are named for dams at their upstream and downstream ends. At times, we may use only the name of the upstream dam.

3 Snake River White Sturgeon Conservation Plan Idaho Power Company

representatives from state, federal, and tribal entities have participated in WSTAC meetings to review study results and resource issues affecting Snake River white sturgeon. During this time, information presented at WSTAC meetings included 1) status surveys of Snake River sturgeon populations, 2) limiting factors for each reach, and 3) modeled results of the population viability analysis (PVA) specific to reaches of the Snake River. In addition, WSTAC participants developed a list of conceptual protection, mitigation, and enhancement (PM&E) measures and discussed recommended PM&E measures. All of this information has formed the basis upon which the WSTAC developed recommended measures for IPC to include in the Snake River White Sturgeon Conservation Plan (WSCP) and submit to the Federal Energy Regulatory Commission (FERC).

IPC proposed the WSCP as a means of developing and implementing PM&E measures directed at white sturgeon populations for impacts of mainstem Snake River hydroelectric projects operated by the company. The WSCP evolved from the recognition that many aspects of Snake River white sturgeon life history and behavior were poorly understood and that factors influencing the health and viability of these populations likely operated differently among reaches. In addition, because little information was available for sturgeon populations in most of the river segments, how actions in one reach might influence the population in another reach was difficult to assess. IPC conducted sturgeon population assessments in the Snake River from Shoshone Falls downstream to the confluence of the Snake and Salmon rivers from 1991 to 2001 (Figure 1). Although obtaining information on population status and resource issues across many reaches has involved a tremendous time commitment, this holistic approach has allowed for the development of riverwide measures that are anticipated to provide the greatest benefits overall to Snake River white sturgeon.

The WSCP is primarily a guidance document: it will guide implementation of PM&E measures for Snake River white sturgeon populations impacted by IPC’s hydroelectric projects to help ensure their long-term persistence and to help restore opportunities for beneficial use, if feasible. The geographic scope of the WSCP includes the Snake River from Shoshone Falls (the natural upstream boundary at river mile [RM] 614) downstream to Lower Granite Dam (RM 107.5). The WSCP describes measures and strategies for Snake River white sturgeon that IPC would implement once the plan were accepted and new project licenses issued by FERC. The WSCP should not be viewed as a management plan, nor is it intended to replace existing management plans for Snake River white sturgeon. IPC recognizes the jurisdiction and management and protection responsibilities of the U.S. Fish and Wildlife Service, Idaho and Oregon fish and wildlife agencies, and Native American tribes.

2. BIOLOGY OF WHITE STURGEON

2.1. Description

White sturgeon belong to the primitive family Acipenseridae that appeared approximately 100 million years ago during the upper Cretaceous period (Smith 1990). They are found in river systems with access to the Pacific Ocean from central California to the Aleutian Islands of

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Alaska. Eight species of sturgeon occur in North America. The white sturgeon is one of five species in the genus Acipenser. White sturgeon have no scales; the body is covered with patches of minute dermal denticles and five rows of bony plates termed scutes. The specific arrangement and number of scutes along the body distinguish white sturgeon from other Acipenser. The body of larger fish is rounded rather than pentagonal. The head is large and broad and comprises almost 25% of the total body length, while the eyes are small. The snout is short and bluntly rounded in adults, but concave and more pointed in juveniles. The mouth is toothless and located on the ventral surface; four barbells are situated in front of the mouth. There are 34 to 36 gill rakers on the first arch. The single dorsal fin has 44 to 48 rays. The paired pectoral fins are large and rounded, with heavily ossified first rays. The skeleton is cartilaginous except for the membrane bones of the skull, jaw, and pectoral girdle. The upper parts of the fish are dark to medium gray with white markings, while the lower parts are pale gray to white (Scott and Crossman 1973).

White sturgeon are generally long lived, and some individuals may reach up to 100 years of age and achieve a maximum length of 6.1 m. While authentic weight records are few, the largest white sturgeon captured purportedly weighed 816 kg; it was caught in the Fraser River near Mission, British Columbia (Scott and Crossman 1973). In the Snake River in Idaho, historic captures of large sturgeon have ranged from 231 kg near Glenns Ferry, 306 kg (at 3.3 m) below Shoshone Falls in 1908, 311 kg near the mouth of the Salmon River, and 680 kg near Weiser in 1898 (Edson 1956). Present-day maximum size approaches 3.4 m, but individuals of this size are uncommon.

2.2. Sexual Maturity

Size or age at first maturity for white sturgeon is extremely variable. Male sturgeon in the wild begin to mature around 125 cm as 12 year olds, while females normally require longer periods, generally 15 to 32 years (PSMFC 1992). In the Snake River, the smallest female sturgeon ranged from 150 cm total length (TL) (previtellogenic), 157 cm TL (early vitellogenic), 159 cm TL (late vitellogenic), and 184 cm TL (vitellogenic or “ripe”) (Figure 2). Overall, the trend suggests that first spawning for females in the Snake River may occur near 165 cm TL and 16 years of age.

Reproductive periodicities (intervals between spawning events) also vary between sexes; males may reproduce every 2 to 4 years, while females may reproduce at no less than 5-year intervals (Conte et al. 1988, Chapman et al. 1996, Anders et al. 2002). Spawn periodicities for some sturgeon individuals may also range up to 11 years (Semakula and Larkin 1968, Simpson and Wallace 1982, Cochnauer 1983). In domestic broodstock used in sturgeon culture, initial egg development requires 2 to 5 years (Binkowski and Doroshov 1985, Conte et al. 1988). Females commonly carry 0.1 to 7.0 million mature eggs, depending on fish size and age (Bajkov 1949, Scott and Crossman 1973, Stockley 1981). Little is known regarding reproductive senescence in white sturgeon. In general, only a fraction (about 10%) of white sturgeon populations are reproductive in any given year (S. Doroshov; University of California, Davis; personal communication to Apperson and Anders 1990).

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2.3. Spawning

White sturgeon depend on free-flowing rivers and seasonal high-flow events for suitable spawning conditions (Parsley et al. 1993, Beamesderfer and Farr 1997). White sturgeon are believed to be broadcast spawners and disperse eggs into the water column where fertilization takes place. White sturgeon spawn in extremely fast-flowing water, with velocities exceeding 1.8 m/s considered the most suitable (Parsley et al. 1993, Parsley and Beckman 1994). Combined with this high-velocity condition, Perrin et al. (2003) noted that Fraser River white sturgeon spawning sites tend to be associated with zones of high hydraulic complexity such as those found at tributary confluences and large side channels of the Fraser River. Researchers have proposed a number of benefits from spawning in fast, turbulent waters. For example, high-velocity flows remove fine sediments from spawning areas, which might otherwise suffocate eggs (Parsley et al. 1993). Also, broadcasting eggs in fast, turbulent water may enhance egg viability by dispersing adhesive eggs, thereby preventing clumping and disease. Dispersal probably also reduces egg and larval predation and minimizes competition among post-larval fish (McCabe and Tracy 1994). In the Snake River, spawners fitted (or tagged) with radio transmitters (telemetered fish) were commonly associated with turbulent pools, high-velocity runs, and nearby rapids (Lepla and Chandler 2001). These telemetered fish used a wide range of depths (2−21 m). Similarly, eggs were also collected from a wide range of depths (4–19 m). The upper range of mean column velocities where telemetered fish were located approached 2.7 m/s in some locations (Lepla and Chandler 2001).

Water temperatures suitable for spawning range from 10 to 18 °C (Parsley et al. 1993). In the Snake River, these temperatures generally occur from March through June, depending on annual spring conditions and the reach location. Lepla and Chandler (2001) documented spawning in the Snake River from April to June while water temperatures ranged between 12 and 17.7 °C. The mean temperature during spawning was 14 °C, which is optimal for white sturgeon egg development (Wang et al. 1985). Most spawning activity occurred between 12 and 16 °C based on back-calculations of developing embryos and observed movement behavior of reproductive adults fitted with transmitters. Based on the temperature regimes in the Snake River, peak spawning activity (12–16 °C) occurs from mid-March through the end of May in reaches between Bliss and Brownlee dams and from late April to mid-June downstream of Hells Canyon Dam (Figure 3). 2.4. Incubation

The optimal water temperature for incubating white sturgeon eggs is 14 °C. Higher temperatures between 18 and 20 °C increase egg mortality, while temperatures above 20 °C are lethal to hatching and other earlier developmental stages of eggs (Wang et al. 1985, 1987). The lower limit for successful incubation is unknown but may be near 6 to 8 °C, similar to the lower limit for other sturgeon species (Wang et al. 1987). Egg incubation usually lasts 7 to 14 days, depending on water temperature (Bajkov 1949, Wang et al. 1985, Conte et al. 1988).

In the Snake River, Lepla and Chandler (2001) found incubating sturgeon eggs in turbulent pools and runs with mean column velocities and depths ranging from 0.1 to 2.0 m/s and from 4 to 19 m. Criteria developed for habitat suitability indices (HSI) indicate that temperatures from 6 to

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20 °C, velocities from 0.79 to 2.6 m/s, depths from 3 to 24 m, and substrates larger than sand are suitable for incubation. Based on HSI criteria, the incubation period should occur primarily from mid-March through early June in the reaches above the Hells Canyon Complex (HCC), which includes Brownlee, Oxbow, and Hells Canyon dams, and from late April to the end of June in the reaches downstream of the HCC (Lepla and Chandler 2001).

2.5. Larvae

Brannon et al. (1986) described three phases of larval development and behavior (dispersal, hiding, and feeding) that occur between hatching and metamorphosis, with each phase lasting up to 6 days depending on environmental conditions. Upon hatching, white sturgeon yolk-sac larvae (10 mm in length) are planktonic and drift downstream with river currents. These yolk-sac larvae can disperse long distances. McCabe and Tracy (1993) and Kohlhorst (1976) reported observing sturgeon larvae about 115 to 121 mi downstream of known incubation and probable spawning sites. Early developing sturgeon larvae hide from predators by burying into gravel substrates, entering the hiding phase earlier in fast water conditions than at slower velocities (Brannon et al. 1984). Suitable substrates may be critical for predator avoidance during this 6-day phase (Brannon et al. 1984). Exogenous feeding begins about 12 days after hatching (based on water temperature of 17 ºC), and larvae disperse into the water column as they begin to feed (Buddington and Christofferson 1985, Conte et al. 1988). Within 20 to 30 days after hatching, metamorphosis is complete (Buddington and Christofferson 1985) and the sturgeon have developed a full complement of scutes and fins.

Mortality of larval fishes is often greatest during the period of transition from endogenous to exogenous feeding (Hjort 1926). Counihan et al. (in press) showed that year-class strength is set within the first few months following spawning and is positively correlated with discharge and negatively correlated with water temperature during the period when spawning and egg incubation is occurring. Larval sturgeon are thought to feed on benthos and periphyton, but they may also exploit pelagic fry and zooplankton (Brannon et al. 1984, Buddington and Christofferson 1985). Predation on post-yolk-sac larvae by other fishes has been noted in laboratory experiments (Brannon et al. 1986); however, such predation is likely reduced as the fish continue to grow and develop scutes.

Although few larval white sturgeon (n = 4) were captured during our sturgeon surveys, larval sturgeon were sampled in both riverine and reservoir environments. Larvae in the riverine environment were sampled at the substrate in a deep, turbulent pool where eggs were also found. One sturgeon larvae was captured in Brownlee Reservoir (4 m below the surface), illustrating the dispersal phase of sturgeon in this life stage and the potential for drift far from spawning sites. Habitats in which larvae were collected had water temperatures of 17 to 18.6 °C, mean column water velocities of 0.0 to 0.9 m/s, and depths of 4 to 14 m. HSI criteria indicate that temperatures of 5 to 27.4 °C, velocities of 0.6 to 2.6 m/s, and depths of 3.9 to 30.4 m constitute suitable habitat for larval rearing.

Based on developmental criteria by Wang et al. (1985) and the stage of development of eggs collected by IPC in the Snake River, the majority of yolk-sac larvae are free swimming and exogenous feeding by late June in reaches between Bliss Dam and the confluence with the

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Salmon River and by mid-July in reaches downstream of the Salmon River (Figure 3) (Lepla and Chandler 2001).

2.6. Young-of-Year

Young-of-year (YOY) sturgeon grow rapidly in laboratory/culture environments. During the sturgeon’s first four months of life, their body weight doubles (at 16 °C) every two to three weeks (Brannon et al. 1984). YOY sturgeon less than 20 cm long may feed on small crustaceans (PSMFC 1992), diptera (Schreiber 1960), and polychaetes (Turner and Kelly 1966). Crustaceans have been identified as the most important food item for sturgeon less than 72 cm in the lower Columbia River (McCabe and Hinton 1990). In the lower Columbia River, McCabe and Hinton (1990) collected YOY sturgeon (July–October) in water 4.0 to 37.5 m deep.

Based on habitat information from McConnell (1989) and Parsley and Beckman (1994), HSI criteria for YOY white sturgeon in the Snake River indicate that temperatures of 0.1 to 28 °C mean column water velocities of 0.0 to 1.9 m/s, and depths greater than 6.1 m are suitable for YOY sturgeon. Lepla and Chandler (2001) estimated that YOY sturgeon begin appearing in various reaches of the Snake River from mid-April through early June (Figure 3).

2.7. Juveniles and Adults

Sturgeon are classified as juveniles until they reach sexual maturity. As mentioned earlier, for males in the wild, first maturity is thought to occur around 12 years of age and 125 cm in length (PSMFC 1992). For wild female sturgeon, the reproductive maturity occurs somewhat later, ranging between 15 and 32 years of age (PSMFC 1992).

Parsley et al. (1989) noted that Columbia River juvenile sturgeon (20–90 cm fork length [FL]) used a variety of depths: they captured juveniles in deep water with trawls and in shallower water with gill nets. Most of the juvenile sturgeon (30–79 cm FL) collected by trawls in The Dalles and Bonneville pools of the Columbia River were captured at water depths of 10 to 17 m (Parsley et al. 1989, Duke et al. 1990). In the Snake River in the upper reaches of Hells Canyon, Coon et al. (1977) found large numbers of juvenile sturgeon (46–91 cm FL) inhabiting deep pools with predominately sand substrates.

Two- and three-year-old sturgeon (20–60 cm) are known to feed on tube-dwelling amphipods, mysids, isopods, and other benthic invertebrates such as chironomids, as well as on the eggs and fry of other fish species (Cochnauer 1983, Partridge 1983, PSMFC 1992). As sturgeon reach approximately 60 cm in length, their diets diversify and they begin to eat fish (Muir et al. 1988, PSMFC 1992). Other items found in the sturgeon’s diet include small mollusks and crayfish (Bajkov 1949, McKechnie and Fenner 1971). They have also been known to exploit seasonal prey items such as salmonid and lamprey carcasses (Galbreath 1979).

As sturgeon reach adulthood, growth rates slow and increasingly more energy is used for developing gonad tissue. Large sturgeon may hold or rest in deeper water (Bajkov 1951, Haynes et al. 1978, Cochnauer 1983). Although large sturgeon commonly use deeper pools, movement

8 Idaho Power Company Snake River White Sturgeon Conservation Plan studies indicate that they also use shallower water (Haynes et al. 1978, Lepla et al. 2001). Habitat use may not only be influenced by depth, but may also include food availability, water temperature, or light penetration (Haynes et al. 1978, Stockley 1981). Downstream of Hells Canyon Dam, Coon et al. (1977) found that mid-sized (91–183 cm TL) and large (> 183 cm TL) sturgeon were more abundant in smaller, more turbulent pools.

Observations of habitat use of both riverine and reservoir environments by juvenile and adult white sturgeon suggest that sturgeon can use a wide range of habitat conditions (Lepla and Chandler 2001). In riverine environments, sturgeon were often captured along current breaks in or near the thalweg of runs and pools. Sturgeon captured in reservoirs tended to use the middle and upper transition areas of the reservoirs and rarely used the lower end of the reservoirs near the dams. During IPC sturgeon surveys, juvenile and adults were captured in water temperatures between 8 and 24.2 °C, with most occurring between 12 and 23 °C. Juvenile and adult sturgeon were captured most often at depths greater than 5 m and mean column water velocities less than 1.25 m/s. Some sturgeon were found at sites with relatively high velocities (1.62–2.8 m/s) or very shallow depths (less than 3 m). However, because these observations were few, white sturgeon apparently prefer these environments less.

Dissolved oxygen (DO) levels at locations where IPC sampled juvenile and adult white sturgeon ranged from 7.3 to 15.1 mg/l. To minimize stress and potential mortality to captured sturgeon, we did not sample when the near-substrate DO level was less than 70% saturation. Linear relationships applied to data developed by Klyashtorin (1974) for several species of Russian sturgeon showed that DO values of less than 4.4 mg/l reduced growth, while levels of less than 1.8 mg/l were generally considered lethal in water temperatures of 3 to 28 °C.

2.8. Movement

Members of the family Acipenseridae migrate for two basic reasons: feeding (rearing) and reproduction. Generally, sturgeon migrate upstream to spawn and downstream to feed (Bemis and Kynard 1997). Historically, white sturgeon could move freely between the ocean, estuaries, the Columbia River (Cochnauer et al. 1985), and the Snake River upstream as far as Shoshone Falls (Coon 1978). The mobility of this fish gave it access to diverse spawning, rearing, and feeding habitats. This access was effectively reduced or halted by construction of dams. Construction of dams on the Snake River has converted 37% of the free-flowing habitat to reservoir habitat (Cochnauer 1983), in addition to creating impassable barriers (Table 1).

Migration patterns of sturgeon vary considerably by species. In the lower Columbia River, seasonal distribution patterns of white sturgeon suggest a general upstream migration in the fall, a quiescent winter period, a downstream migration in the spring, and a large congregation of sturgeon in the estuary during summer. DeVore and Grimes (1993) suggested that these migration patterns are a result of ephemeral food availability. However, Bajkov (1949) found that some white sturgeon did not appear to migrate at all during a particular year. North et al. (1993) also reported variations in movement patterns of white sturgeon in three Columbia River reservoirs above Bonneville Dam. Of the sturgeon sampled, half the fish moved downstream after release, while the other half moved upstream. Most sturgeon moved at least 0.6 river miles, with some individuals traveling up to 94 river miles.

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Over the course of ten years of tracking sturgeon in reaches of the Snake River between Bliss Dam and the mouth of the Salmon River, IPC investigators observed similar variations in movement patterns of telemetered sturgeon. In general, sturgeon in reservoirs showed more movement between monitoring events than fish residing in free-flowing sections of the Snake River (Lepla and Chandler 1995a, Lepla et al. 2001). Sturgeon in reservoirs often traveled within the middle and upper sections of the reservoirs, whereas fish movement in the free- flowing sections of the Snake River remained more localized. Lepla and Chandler (1995a) speculated that these differences in movement patterns were related to differences in feeding behaviors for riverine and reservoir environments. In free-flowing sections, food items carried by the river currents could settle out in habitats used by sturgeon; in a reservoir, sturgeon had to search more actively.

For sturgeon that were at large for 193 to 648 days (n = 7), each moved more than 60 river miles. Overall, sturgeon movement was fairly localized during IPC’s monitoring efforts, with the majority (61–91%) of fish moving less than 10 river miles from their initial capture locations (Figure 4). Based on all telemetry observations, the average distance moved by Snake River sturgeon ranged from 0.4 to 4.0 river miles. Others (n = 32) that were at large for similar durations (185–679 days) moved less than 10 river miles. Coon (1978) observed similar localized movement patterns: sturgeon greater than 183 cm below Hells Canyon Dam often moved only among pools that were close to each other. He noted that smaller sturgeon tended to move downstream but averaged only around 7 km (4.4 mi) per year.

RL& L Environmental Services (2000) reported similar movement behavior for white sturgeon in the Fraser River, an undammed river system. Telemetry data for female and male white sturgeon in various stages of maturity and segments of the Fraser River showed mean movement (average of all observations) of individuals ranging from 0.0 to 6.7 miles. The authors also noted that several sturgeon exhibited extensive movement exceeding 25 river miles, some of which moved more than 43 river miles between monitoring efforts. Overall, sturgeon monitored during their telemetry studies displayed localized movements that most commonly ranged less than 6 river miles. This finding suggests that discrete sections of the Fraser River provided suitable white sturgeon habitats to complete life history functions. In the Nechako River, a tributary to the Fraser River, sturgeon commonly moved more than 9 river miles (maximum movements ranged in direction from 38 river miles upstream to 45 river miles downstream). These movements are thought to be an adaptation of a feeding strategy to exploit the sockeye salmon migration through this river system. Similar large-scale movements that appear necessary because of geographic separation between supporting different life history functions—such as feeding, spawning, and overwintering—have also been observed in other river systems, such as the Kootenai River (Apperson and Anders 1991) and Lake Roosevelt (Brannon and Setter 1992).

The most notable movements that IPC investigators observed in the Snake River were associated with spawning. In these instances, the distance sturgeon moved depended on their proximity to suitable spawning habitat (Lepla and Chandler 2001). This behavior was particularly evident among sexually mature sturgeon moving from reservoir to riverine environments. In C.J. Strike Reservoir, reproductive adults often left the pool as temperatures approached suitable levels for spawning and, depending on their capture location in the pool, moved as much as 16 river miles upstream of the pool to stage and spawn near RM 521.8. Similar upstream spawning movements, although typically less than a few miles, were observed among sturgeon below C.J. Strike and

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Oxbow dams as they sought suitable spawning conditions that generally occurred only near the tailraces (Lepla and Chandler 2001).

Spawning-related movements in the river canyon corridors below Bliss, Swan Falls, and Hells Canyon dams were often more random than those observed in the reaches below C.J. Strike and Oxbow dams. These lesser defined movements were likely due to the presence of numerous pools with nearby high-velocity runs for staging and the presence of high-velocity deep runs that provided suitable spawning habitat. These conditions were absent in the reaches below C.J. Strike and Oxbow dams. The distances that we observed spawners migrate varied by reach: sturgeon migrated 0.3 to 9.0 river miles between King Hill and Bliss Dam, 1.5 to 6.0 river miles below Swan Falls Dam, and 0.0 to 2.0 river miles below Hells Canyon Dam. None of the telemetered spawners in these river segments traveled upstream as far as the tailraces of the dams (Lepla and Chandler 2001).

Lepla and Chandler (2001) also observed several spawners exhibit post-spawning behavior by departing, generally downstream, from spawning areas within a few weeks, although this behavior also varied. For example, spawners from C.J. Strike Reservoir typically returned downstream to the reservoir by late May. Below Hells Canyon Dam, we observed similar behavior in two female sturgeon that departed downstream. The distance these fish moved downriver ranged from 13 to 61 river miles, followed by return movements back upstream (24−31 river miles) by the middle of summer. Still other sturgeon remained at spawning sites and displayed no discernable post-spawning movement at all. Overall, the predominantly localized movement by reproductive and nonreproductive sturgeon suggests that several sections of the Snake River provide suitable habitat for all life history functions, including feeding, adult holding, overwintering, and spawning (Lepla et al. 2001).

As discussed above, movements of most sturgeon were highly localized, although some juvenile and adult white sturgeon moved downstream past dams in reaches of the middle Snake River. Lepla and Chandler (1995a, 1997) recaptured 15 hatchery sturgeon below Bliss Dam and 6 sturgeon (4 wild and 2 hatchery) below C.J. Strike Dam that had been originally stocked or tagged upstream of these projects. In contrast, no sturgeon (wild or hatchery) that had originally been tagged above the HCC were sampled downstream of Hells Canyon Dam during IPC’s sturgeon surveys. Based on mark-recapture data, IPC estimated that 2% of the sturgeon population between Bliss and C.J. Strike dams, on average, move downstream past C.J. Strike Dam annually (IPC unpublished data).

The environmental cues that drive older life stages of sturgeon to move downstream from one reach to another are not understood. These sturgeon may be seeking additional rearing and feeding habitats. For instance, the Idaho Department of Fish and Game (IDFG) released 2,560 hatchery-reared sturgeon (mostly age-1) in the 13-mile segment between Lower Salmon Falls and Bliss dams during the 1989–1994 period. Some of these stocked fish may have moved into the next downstream reach to search for additional rearing habitat for which there was less competition. Still, other sturgeon from these stockings remained and were recaptured at the same release point (the Lower Salmon Falls tailrace) five years later (IPC unpublished data).

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3. ANTHROPOGENIC IMPACTS TO WHITE STURGEON

3.1. Dams and Reservoirs

Historical (pre-1900) habitat in the Columbia and Snake rivers and estuary constituted a mosaic of diverse habitats. These habitats were fragmented by different geomorphic features of the river channel, including variations in channel depths, widths, gradients, alluvial and colluvial deposits, and bedrock constrictions. This mosaic of diverse habitats supported all life stages of white sturgeon and the ecosystem in which they evolved. The ability for white sturgeon to move between habitats for various life history functions and seasonal availabilities of prey items may have been essential. Construction of dams in the Columbia and Snake rivers (beginning as early as 1900) reduced the diversity of habitats available to white sturgeon and fragmented the river into sections with generally fewer types available. In some segments, a full complement of habitat was available for all life stages; in other segments, critical habitat elements were altered or unavailable.

Each fragmented segment has unique characteristics that influence its ability to sustain a population. In many instances, the fragmented segment may be too small to support enough spawners within any given year, and the population may be especially vulnerable to stochastic events that cause year-class failures. Populations within short segments are also vulnerable to downstream losses that even further reduce the production potential within the reach. As discussed above, sturgeon larvae have evolved to disperse long distances with river flow and are therefore essentially lost from contributing to recruitment within the reach where they were spawned. While these conditions may contribute to sturgeon populations in downstream reaches, the shorter reaches gradually lose their populations.

In addition to downstream larval distribution, older age classes of white sturgeon also move downstream out of river segments, particularly in shorter reaches. Downstream movement between river segments is possible either through the turbines (called entrainment) or through spill gates during periods of spill. Entrainment has a high risk of mortality for larger fish because they have a higher probability of being struck by the turbine blades. There is also a risk to white sturgeon of injury or mortality when they pass through the spill gates, but this risk is much lower.

Downstream losses (especially to downstream larval drift) likely decrease with distance. In addition, longer reaches typically have greater habitat diversity, which enables them to support all critical life stages within the reach. They are also more capable of supporting the larger numbers of spawning adults needed to sustain a population. The challenge of sustaining populations of white sturgeon in a system of increasing fragmentation by dam construction was demonstrated in a simulation study by Jager et al. (2001a). They found that increased fragmentation produced an exponential decline in the likelihood of population persistence.

With one exception, this relationship between reach length and improved recruitment and stock structure appears to hold true in the Snake River system. Although the Swan Falls–Brownlee reach is the longest reach remaining in the Snake River system, it displays little evidence of

12 Idaho Power Company Snake River White Sturgeon Conservation Plan recruitment and the population abundance remains low. In this instance, the low population size is thought to be caused by poor water quality. The remaining long reaches support the four largest populations (in descending order, both by reach location and population size): Hells Canyon–Lower Granite, Bliss–C.J. Strike, C.J. Strike–Swan Falls, and Shoshone Falls– Upper Salmon Falls. The remaining five reaches, with lengths from 26 down to 1.2 miles, show little evidence of being able to support sturgeon populations through natural (and, in some cases, even hatchery-supplemented) means. As previously mentioned, habitat that is capable of supporting all life stages is limited. Additionally, these five shorter Snake River reaches are more likely to lose fish through export, particularly the larval life stages, due to their early life history behavior.

Dams have also altered the seasonal flow regime of the river, which renders some habitats temporally out of synchronization with key life history functions such as spawning. In some cases, reservoir construction has altered water quality, such as temperature and DO, and reduced the system’s ability to redistribute nutrients and substrate materials that commonly occurred during the spring freshets. These changes to the riverine environment have altered the composition and abundance of prey. Development of reservoirs enhance environments for some species, allowing them to increase beyond historical levels, and creates habitats suitable for many introduced species, which may increase competition and predation experienced by sturgeon.

3.2. Flow Regulation

The Snake River is one of the most extensively regulated and diverted rivers in North America (Palmer 1991). Between the headwaters originating in Wyoming downstream to its confluence with the Columbia River, 20 major facilities on the mainstem Snake River are used to either store water for irrigation, flood control, or hydropower (Figure 5). Because several of these dams in the upper Snake River basin were built to allow water to be captured, stored, and diverted for irrigation, they alter the hydrograph pattern and considerably reduce the overall flow of the Snake River. Almost half of the estimated volume of the Snake River is diverted for agricultural purposes (Miller et al. 2002). For example, river flows passing over Shoshone Falls largely depend on the amount of water released at Milner Dam. Although the average annual flow below Milner Dam is nearly 3,200 cubic feet per second (cfs), all of the water in the Snake River at Milner Dam can be diverted for irrigation purposes during the irrigation season (April through October). While a target flow of 200 cfs has been established as a release goal below Milner Dam, at times, flows below the dam have been reduced to zero (FERC 2002a, USEPA 2002). During the irrigation season when most of the river is diverted, groundwater springs are the primary source of river flow in this area of the Snake River. Figure 6 shows the estimated natural flow compared with the observed flow for the Snake River near Milner Dam (RM 639) and the Boise River near Parma, Idaho (RM 392) (Miller et al. 2002). Table 2 summarizes the historical timeline of storage-facilities construction within the Snake River basin upstream of Hells Canyon Dam.

White sturgeon depend on riverine habitats and seasonal floods to provide suitable spawning conditions. Seasonal flow patterns likely cue maturation, migration, and spawning. Adhesive eggs are broadcast over rocky substrates in turbulent high-velocity habitat that accompanies high

13 Snake River White Sturgeon Conservation Plan Idaho Power Company

flow. High flows help disperse eggs and juveniles and exclude predators. Periodic floods also flush fine sediment from riverbed cobble and prevent armoring. Sedimentation and armoring reduce suitability for egg incubation, larval and juvenile fish rearing, and invertebrate diversity (UCWSRI 2002).

As a result of water management activities in the upper Snake River basin involving irrigation and, to a lesser degree, flood control, the spring hydrograph downstream (but upstream of Brownlee Reservoir) can be altered substantially during some years. The reduction of spring flows results primarily from the refilling of upstream U.S. Bureau of Reclamation (USBR) storage projects drafted the previous year for agricultural purposes. In addition, upper basin water management activities potentially shift peak spring flows that do not coincide with optimal spawning temperatures for sturgeon during some years (Figure 7). This shift can result in reduced spawning and early-rearing habitats for sturgeon. Recruitment of juvenile sturgeon has been widely correlated with the volume of spring flow. Several researchers have reported a positive relationship between spring river flow and recruitment for many species of sturgeons including Siberian sturgeon (A. baeri) (Tsyplakov 1978, Votinov and Kas’yanov 1978), lake sturgeon (A. fulvescens) (Auer 1996), and white sturgeon (Kohlhorst et al. 1989, Miller and Beckman 1995, Counihan et al. in press). Positive relationships between the quantity of flow and white sturgeon spawning habitat have also been described by Parsley and Beckman (1994), Chandler and Lepla (1997), and Brink and Chandler (2000).

Hydrosystem operations also result in daily flow fluctuations for power production and potentially affect recruitment success. Instream flow studies conducted below Lower Salmon Falls, Bliss, C.J. Strike, and Hells Canyon dams have shown that load-following operations can substantially reduce the amount of spawning, incubation, and larval habitats for white sturgeon, particularly during low water years. During above-normal water years, estimated spawning habitat was not typically impacted because high spring flows often exceeded plant capacities and created run-of-river conditions. Studies downstream of a lower Columbia River dam have shown that peaking operations can result in the scouring of eggs and embryos from the riverbed (Counihan and Parsley 2001). However, successful spawning and recruitment of white sturgeon have also been observed downstream of lower Columbia River and Snake River (Hells Canyon) dams that are operated for peaking. Studies on Russian sturgeon have identified undesirable changes in behavior and maturation following highly fluctuating winter discharges; changing environments required sturgeon to maintain an increased level of activity. However, similar effects have not been documented for white sturgeon, and recent studies downstream of John Day Dam on the lower Columbia River documented that white sturgeon positioned within the tailrace of the dam during the spawning period were not influenced by operations at the dam (M. Parsley, U.S. Geological Survey, personal communication in UCWSRI 2002). Evaluations of IPC project operations on white sturgeon habitats in the Snake River are presented in IPC technical reports by Brink (2000) for the Lower Salmon Falls–Bliss reach, Brink and Chandler (2000) for the Bliss–C.J. Strike reach, Chandler and Lepla (1997) for the C.J. Strike–Swan Falls and Swan Falls–Boise River reaches, Myers and Chandler (2001) for the Oxbow Bypass reach, and Chandler et al. (2002) for the Snake River downstream of Hells Canyon Dam.

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3.3. Water Quality

Dammed and regulated rivers, although they have become an integral part of our landscape and economy, have fundamentally different ecological and physical processes from undammed and unregulated rivers (Collier et al. 1996). Many of the processes involving the routing and fate of pollutants within these altered systems are not well understood. Additionally, the unique nature of individual reservoirs complicates efforts to understand how a specific system functions (Myers et al. 2001). Impoundment alters hydrodynamic and transport characteristics, water retention time, plant and fish community composition (USEPA 2002), and habitat diversity by reducing the number of rapid and pool areas seen in natural systems (Collier et al. 1996). These processes may vary considerably from year to year.

Water quality within the Snake River has been compromised by the cumulative effects of decades of agricultural and industrial activities (Clark et al. 1998, Harrison et al. 2000). The demands placed on the water resources have transformed this once free-flowing river to one with multiple impoundments; flow diversions; and increased physical, chemical, and microbiological pollutant loadings (USEPA 2002). A review of the Idaho Department of Environmental Quality (IDEQ) and Oregon Department of Environmental Quality (ODEQ) 303 (d) listed waters, based on each segment’s designated beneficial uses, confirms the degree of impairments that exist in the Snake River system (Table 3 and Table 4). Major water quality impairments to the system include the decrease in DO, increase in temperature, influx of contaminants, and periods of elevated total dissolved gas (TDG).

For the reaches upstream of C.J. Strike Reservoir, the river’s water quality is high during most of the year; however, it may decline significantly during low-flow periods typically in mid- to late summer (USEPA 2002). During the summer irrigation season when water is in high demand, diversions and irrigation returns reduce stream flows and degrade water quality. Because the Snake River is lined by cultivated fields, groundwater discharges, fish farms, and municipal wastewater-treatment facilities, return flows display a combination of excessive nitrogen, phosphorus, pesticides, and sediment (Clark et al. 1998). Excessive aquatic vegetation, low DO levels, and high water temperatures—all manifestations of a nutrient-rich, eutrophic water body—prevent water in this reach from meeting state water quality criteria (USEPA 2002).

Conditions from mid- to late summer in these upper reaches also act to drive reductions in downstream water quality. For downstream reaches, use of storage reservoirs for irrigation, flood control, and hydroelectric power reduces stream flow velocities and stream habitat to the detriment of native biological communities. Issues common to lentic, eutrophic systems, such as increased temperature and depressed DO levels, tend to dominate the impounded regions. The remaining free-flowing habitat is degraded by pollutants from Snake River tributaries, some of which are characteristic of those found downstream of urban areas. The Snake River is listed as water quality impaired because of bacteria, nutrients, and sediment near these sources (IDEQ 1998). These tributaries may, in turn, “set the stage” for degraded conditions observed within the HCC (Myers and Pierce 1999).

Sturgeon are sensitive to a variety of water quality problems, including changes in temperature, decreases in DO, additions in nutrients, and the presence of contaminants (NMFS and USFWS 1998). When compromised water quality for sturgeon becomes an issue, it is usually, but not

15 Snake River White Sturgeon Conservation Plan Idaho Power Company always, expressed during the summer when multiple stressors combine. For example, adult and juvenile white sturgeon may tolerate a wide range of temperature and DO levels; however, a combination of high temperature and low DO levels can be lethal (Jager et al. 2002).

Because spawning typically commences in turbulent water near the timing of the spring freshet, temperature effects (rather than DO effects) are more likely to be driving spawning timing, incubation, and larval development. In the Snake River, spawning temperatures generally occur from March through June, depending on annual spring conditions and the reach location. Although suitable temperature ranges are certainly available for early life stages each year, the timing and duration of the suitable range varies depending on water years. It is during these early life stages that year-class strength is thought to be established (Gross et al. 2002). The hydrologic year type for both the current and previous year determine the amount of upstream storage, whereas weather patterns influence agricultural water demand and diversion. These factors ultimately affect the quantity, timing, and duration of suitable water available for sturgeon spawning each year in the Snake River.

3.3.1. Dissolved Oxygen

Low DO conditions commonly occur in several segments of the Snake River during summer and fall months, particularly in areas of C.J. Strike, Brownlee, Oxbow, and Hells Canyon reservoirs and the dam tailraces associated with these reservoirs. In C.J. Strike Reservoir, Myers and Pierce (1997) reported that, at times, the reservoir had very low levels of DO (< 2 mg/l) in the lower 8 miles of the pool. These low oxygen levels generally occur by June and are confined to depths greater than 10 m, potentially restricting sturgeon use in this area during these times. During low and normal water years, 23 to 35% of the bottom 2-m layer in the lower end of C.J. Strike Reservoir can be lethal to sturgeon (Lepla and Chandler 2001). By September, DO levels typically exceed the state criterion of 6 mg/l throughout the reservoir. While the lower levels limit the use of some downstream areas of the reservoir during summer months, Lepla and Chandler (1995a) reported that telemetered sturgeon in C.J. Strike Reservoir generally showed minimal use of the lower end of the reservoir regardless of DO levels. Of the few telemetered sturgeon (n = 4) that did encounter low DO areas (0.75–4.9 mg/l) in the main channel of the lower reservoir (RM 499–502), monitoring efforts showed that these individuals moved to nearby elevated benches (7.6–15.5 m) where conditions were not problematic (> 6.1 mg/l) (IPC unpublished data). Although poor water quality may sometimes limit use of some lower reservoir areas, no sturgeon mortalities have been linked to the periodic low DO levels in C.J. Strike Reservoir. In fact, sturgeon in the Bliss–C.J. Strike reach have some of the highest growth rates and condition factors observed in the Snake River.

Below C.J. Strike Dam, DO levels in the tailrace have been recorded as low as approximately 4.3 mg/l during below-normal water years, but they do not fall below the minimum state standard during higher flow years (1995 and 1996) (Myers and Pierce 1997). The intervals with low DO levels are typically brief, usually lasting less than a week, and do not appear problematic for sturgeon below C.J. Strike Dam (Lepla and Chandler 1997). Oxygen levels are not low enough to cause mortality there: observations of telemetered fish near the dam in 1994 showed little change in movement regardless of whether DO levels were less than or greater than 6 mg/l. In addition, the condition factor of white sturgeon below C.J. Strike Dam is similar to the

16 Idaho Power Company Snake River White Sturgeon Conservation Plan condition factor observed for sturgeon in the free-flowing section below Bliss Dam where DO levels meet the state criterion.

Low DO levels also occur within the HCC, resulting in suboptimal, or in some cases lethal, conditions for white sturgeon. During low-flow years, low DO conditions lethal to sturgeon can exist in up to 80% of the bottom 2-m layer of Brownlee Reservoir (Lepla and Chandler 2001). In worst-case scenarios, the transition zone at the upstream end of the reservoir can become anoxic throughout the water column. In mid-July 1990, low river inflows and excessive nutrient levels resulted in DO levels (< 0.86 mg/l) throughout the water column that were lethal for sturgeon near the upper end of Brownlee Reservoir (RM 324). These lethal DO conditions (less than 1 mg/l), possibly exacerbated by high water temperatures (25–26 °C), caused the deaths of at least 28 adult white sturgeon near the upper end (RM 324) of Brownlee Reservoir (IDFG 1990).

Oxbow and Hells Canyon reservoirs also experience severe water quality conditions during low water years as a result of receiving anoxic water from Brownlee Reservoir. Although no sturgeon mortalities have been attributed to poor water quality in these two reservoirs, low DO levels lethal to sturgeon can exist in up to 73% of the bottom 2-m layer in Oxbow Reservoir and 42 to 55% in Hells Canyon Reservoir during summer months of low-flow years (Lepla and Chandler 2001). Below Hells Canyon Dam, DO levels measured in the tailrace can also drop as low as 2.8 mg/l for several weeks during late summer. This condition may persist for several miles until reaeration from downstream rapids occurs. Habitat data collected over telemetered sturgeon 9 miles downstream of Hells Canyon Dam showed that DO recovered to levels near 7 mg/l. Given the relatively brief period of low DO conditions that occur near the most upstream end of this reach, the risk of mortality to this sturgeon population is low. However, periodic low DO conditions may be influencing sturgeon distribution near the dam. Sampling results from a survey conducted between Granite Rapids (RM 239.2) and Hells Canyon Dam in 2002 by IPC found few sturgeon (n = 5) between the dam and Wild Sheep Rapids (RM 241.2). The number of sturgeon captures between Wild Sheep and Granite Rapids was markedly higher (n = 35). During this survey, DO values ranged between 4.8 and 8.6 mg/l (IPC unpublished data).

No quantitative information is available on DO thresholds for white sturgeon across a wide range of temperatures. Studies on hypoxia and white sturgeon generally discuss only one to three temperature observations or simply describe behavioral responses to hypoxia (Burggren and Randall 1978, Cech et al. 1984, Ruer et al. 1987, Crocker and Cech 1997). Klyashtorin (1974) studied the DO thresholds of four Russian species of sturgeon (0.36 kg) over a range of oxygen and temperature levels and found that DO values less than 4.5 mg/l reduced growth, while levels less than 1.8 mg/l were lethal at upper temperature ranges. Klyashtorin found similarities among these four sturgeon species and speculated that other members of the sturgeon family may have DO sensitivities similar to those species investigated. This assumption appears to be strengthened by the work of Burggren and Randall (1978) who evaluated the effects of hypoxia on 1-kg white sturgeon at one water temperature. They reported a sharp decrease in respiration activity for white sturgeon at levels below 3.9 mg/l (60 mm Hg at 15 °C), a finding that is consistent with Klyashtorin’s results.

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3.3.2. Temperature

White sturgeon are considered a cool/coldwater species, a classification that suggests they are better suited to water temperatures below 25 °C. In culture facilities, water temperatures from 18 to 22 °C are considered optimal for sturgeon growth; California sturgeon farms often use this temperature range for production (S. Doroshov; University of California, Davis; personal communication). Water temperatures above 23 °C appear to increase stress and the likelihood of temperature-related mortality for some white sturgeon. During IPC field studies, we observed a decline in catch rates as temperatures exceeded 23 °C. Signs of stress, such as redness of ventral surfaces and fins, appeared more frequently during capture and handling in higher temperatures than they did during sampling at lower temperatures. Similar observations of temperature-related stress were documented at Pacific Northwest National Laboratories (PNNL), operated by Battelle, in Washington. Juvenile sturgeon undergoing acclimation from 17 to 24 °C quit feeding, and three fish died (D. Geist, PNNL, personal communication).

The extent of temperature-related mortality in Snake River sturgeon populations is unknown. Water temperatures in several reaches of the Snake River routinely peak near 24 to 25 °C during the summer. These increased temperatures might increase the risk of mortality; however, no sturgeon mortalities have been directly attributed to these elevated temperatures. Our telemetry studies tracked several Snake River sturgeon throughout summer maximums approaching 24 to 27 °C and found no mortality among these individuals. Although the upper lethal threshold temperature for white sturgeon is unknown, it likely occurs somewhere between 28 and 30 °C. We posed our assumption to S. Doroshov (University of California, Davis; personal communication) who believed that it was accurate.

Water temperature can exceed state standards for coldwater biota in several reaches of the Snake River (Myers et al. 1995; Myers and Pierce 1997, 1999). Idaho has established coldwater biota temperature criteria of 22 °C for the instantaneous maximum and 19 °C for the daily average (IDAPA 58.01.02 n.d.). Similarly, Oregon has set a criterion of 17.8 °C for the 7-day average maximum (OAR 340-041 n.d.).

In reaches of the Snake River between Shoshone Falls and Bliss dams, mean daily water temperatures during summer months generally peak near 19 to 20 °C. Maximum instantaneous temperatures of water passing through the Upper Salmon Falls, Lower Salmon Falls, and Bliss projects were at levels that could fully support coldwater biota and could typically support salmonid spawning from October to March. However, using the mean daily water temperature criterion, temperatures approached or slightly exceeded the upper limit for fully supporting coldwater biota during July, and exceeded the level identified to support salmonid spawning most (> 85%) of the year (Myers et al. 1995). The reservoirs associated with the Upper Salmon Falls, Lower Salmon Falls, and Bliss projects each increase the water temperature by an average of 0.1 °C (IPC 2000a).

Based on temperature records collected during the 1993–1995 period for the C.J. Strike Project, the maximum daily average temperature criterion for coldwater biota was exceeded during the summer months in the reservoir and in the tailwater. Water temperatures in the C.J. Strike tailwater can peak near 25 °C during the summer, exceeding the state coldwater biota criterion. C.J. Strike Reservoir temperatures were similar in the Snake River arm of the reservoir, but were

18 Idaho Power Company Snake River White Sturgeon Conservation Plan slightly higher (peaking near 26 °C) in the Bruneau arm of the impoundment. Water quality models have helped describe how C.J. Strike Dam influences water temperature. Water temperature was evaluated with and without the reservoir in place using the CE-QUAL-W2 model (COE 1994) and 1994 conditions (IPC 2000b). The year 1994 was characterized by lower than normal flow conditions combined with higher than normal air temperatures. Based on the simulation, it was estimated that the temperature of water leaving the reservoir was an average of 0.65 °C warmer than it would have been under free-flowing conditions. Under hot summer weather conditions, the simulation showed that water temperature could increase by up to 2 °C from delayed passage through the reservoir. The simulation also showed that the presence of the reservoir resulted in daily average temperature exceeding the 19 °C maximum daily average standard on ten occasions between June and September 1994: water temperatures under free- flowing conditions would have met the standard (FERC 2002b).

Water flowing into the HCC and within Brownlee Reservoir exhibits some of the warmest temperatures that Snake River sturgeon may experience. Downstream of Swan Falls Dam, high summer temperatures over the relatively shallow water coursing through over 100 miles (RM 444–340) of low-gradient river plain help create these conditions. Maximum water temperatures in the Snake River upstream of Brownlee Reservoir near Weiser, Idaho, can reach 27 °C during the late summer. These conditions, combined with high nutrient loading, cause Brownlee Reservoir to stratify seasonally: during this time, the reservoir may develop an extensive hypolimnetic layer for at least half of its length. Summer water temperatures near the surface of Brownlee Reservoir (< 1 m) during July and August can range from 24 to 31 °C (Lepla and Chandler 2001). Sturgeon captured in the upper end of Brownlee Reservoir showed considerably lower condition factors and higher stress indicators than those captured in similar habitats of C.J. Strike Reservoir. Although these physical effects are not thought to be attributed entirely to high temperatures, the temperatures speed the nutrient processing and create low DO conditions where the effects manifest. In the water leaving Brownlee Reservoir, as well as the downstream reservoirs, temperatures are generally cooler than inflowing water temperatures in spring and summer, with temperatures warmer than inflow in the fall (Myers et al. 2001). These differences are artifacts of the stratification that occurs in Brownlee Reservoir, the large water volume in the HCC, and the depth of Brownlee Dam’s intakes (approximately 40 m below the full pool elevation).

3.3.3. Contaminants

A reduction in water quality by the excessive loading of nutrients and contaminants can affect the viability of sturgeon in a system (Jager et al. 2001b, Kruse 2000 and citations within). Studies by Wilcove et al. (1998) found that pollution is currently ranked second only to habitat loss as a cause of endangerment for aquatic animals. While contaminants are known to control wild populations through their lethal effects on individuals, nonlethal concentrations of contaminants can also reduce population viability by reducing the reproductive success of individuals (Webb 2002).

The life history of white sturgeon may leave them more vulnerable to effects from bioaccumulative pollutants. As opportunistic bottom feeders, these fish frequently come into contact with sediments that could contain sediment-sorbed hydrophobic pollutants such as PCBs,

19 Snake River White Sturgeon Conservation Plan Idaho Power Company chlorinated pesticides, and chlorinated dioxins and furans (Webb 2002). These contaminants could be ingested incidentally during normal feeding or contained in food items and bioaccumulated. Because white sturgeon are a long-lived species, they have increased opportunities for exposure to and bioaccumulation of contaminants.

Effects can vary from reduced condition factor (Foster 2002), reduced reproductive success (Webb 2002), or elevated mortality of early life stages (Kruse 2000). While exposure to contaminants may not be lethal to adult sturgeon, the conditions may present barriers to the development of early life stages. In studies conducted on Kootenai River white sturgeon, Kruse (2000) found a significant positive correlation between PCB concentrations in embryos and mortality. Kruse found that PCBs, heavy metals, and DDT (or its metabolites) were found to bioaccumulate in ovarian tissue. Kruse also indicated that larger eggs, characteristic of older adults, were more susceptible to increased exposure and had higher total organochlorine concentrations, a finding the confirmed bioaccumulation of these compounds in sturgeon eggs. Even more compelling, Kruse (2000) exposed incubating Kootenai River white sturgeon embryos to three test habitats. These test habitats included filtered river water, unfiltered river water, and unfiltered river water with river sediments. Survival in the group exposed to filtered river water was significantly higher than survival in the other test groups, suggesting that the sediments may have included contaminants that lower incubation success.

It is possible that conditions such as these contribute to the low recruitment observed in the Swan Falls–Brownlee reach where mainstem and tributary water quality conditions remain some of the most degraded within the Snake River (Hoelscher and Myers 2001). State and federal governing agencies have identified the Swan Falls–Brownlee reach as one of concern regarding water quality (IDEQ 1998). Water quality in this reach is being addressed by the governing agencies with the development of a total maximum daily load allocations (TMDL) plan. Under the TMDL plan, water users within the watershed are given load allocations, after which they must comply or mitigate for excesses above their allocations. Studies to assess the baseline conditions and chemical interactions taking place at the substrate interface are currently underway in the Swan Falls–Brownlee reach (Harrison et al. 2000).

3.3.4. Total Dissolved Gas

The effects of hydroelectric operations on total dissolved gas levels are well documented (Weitkamp and Katz 1980). Although slightly elevated levels of TDG can occur naturally in rivers, levels exceeding 100% saturation2 commonly occur below large-scale hydroelectric facilities along the Columbia and Snake rivers. The state (Idaho, Oregon, and Washington) standards for protecting aquatic biota, which have been set at 110% supersaturation, are commonly exceeded during spill episodes (inflows exceed plant capacity) at hydroelectric plants. Gas supersaturation downstream of a dam typically occurs when air becomes entrained in water that is released over a spillway and plunges deep into a stilling basin. The hydrostatic pressure at depth causes entrained atmospheric gases to be absorbed into solution. This process creates supersaturation of gases relative to surface or atmospheric pressures.

2 Levels above 100% saturation are referred to as supersaturated.

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Gas supersaturation can harm aquatic biota. Fish experience gas bubble trauma when the sum of dissolved gas pressures in their body fluids exceeds the compensating pressures of hydrostatic head, blood, tissue, and water surface tension. Gas bubbles form in the blood and tissues of fish, creating physiological dysfunction (Bouck 1980). Common external signs of gas bubble trauma include bubbles or blisters under the skin of fin rays, the head, or the lining of the mouth, or along the lateral line. Bubbles and blisters often cause lesions and hemorrhaging. Exophthalmia, a condition commonly known as popeye, may occur. However, this problem usually requires long-term exposure to uncompensated gas pressure. If a fish is exposed long enough to uncompensated gas pressure, gas bubble trauma can lead to its death.

The effects of supersaturation on aquatic organisms depend on the depth distribution of the organisms. Each meter of depth increases the solubility of the dissolved gases to compensate for approximately 10% of the supersaturation. For example, a surface reading of 120% corresponds to a compensated TDG of 110% just 1 m below the surface. Therefore, in large rivers with elevated TDG levels, most of the water volume is unlikely to be supersaturated (Weitkamp 1974). Excessive TDG levels relative to the surface represent a greater threat to organisms in shallow water than in deeper water. Given that the white sturgeon is a benthic species, elevated TDG levels likely do not affect most life stages. However, the timing and dispersal of white sturgeon larvae from incubation areas make the larval life stage potentially vulnerable to the effects of elevated TDG levels (Counihan et al. 1998). Upon hatching, sturgeon larvae disperse by entering the water column where they may be exposed to water depths with insufficient hydrostatic pressure to compensate for high TDG levels.

A laboratory study on the effects of dissolved gas supersaturation on white sturgeon larvae showed 50% mortality after a 13-day exposure to 131% TDG. However, no mortality occurred following a 10-day exposure to 118% TDG (Counihan et al. 1998). The authors indicated that these study results may represent a worst-case scenario since the exact depth at which white sturgeon larvae disperse downstream is unknown (Counihan et al. 1998). Applying the general rule of 10% reduction in TDG for every meter, larvae in the Snake River that are dispersing at depths greater than 2 to 3 m would have sufficient hydrostatic pressure to compensate for TDG levels as high as 139%.

Excessive levels of TDG resulting from IPC project operations (spilling water) occur primarily at C.J. Strike, Brownlee, Oxbow, and Hells Canyon dams. Measured levels in the C.J. Strike, Brownlee, and Oxbow tailraces generally range from 120% to 125% saturation during spill episodes (IPC 2000c, Myers and Parkinson 2002). In the Hells Canyon tailwater, measured levels peak around 135% saturation. Although supersaturation levels decline in the Snake River as water flows downstream of Hells Canyon Dam, levels in excess of 110% saturation can persist downstream to the confluence with the Salmon River (Myers and Parkinson 2002). However, IDFG personnel have indicated that very little trauma from high TDG has been observed in white sturgeon below Hells Canyon Dam and is unlikely to be a significant source of risk to this population (T. Cochnauer; IDFG; personal communication to the WSTAC, May 8, 2001). Elevated TDG levels resulting from IPC project operations at Upper Salmon Falls, Lower Salmon Falls, Bliss, and Swan Falls dams are less frequent and do not exceed 112% (Myers et al. 1995, IPC unpublished data).

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3.4. Genetics

Sturgeon populations that have become isolated, either by natural or artificial barriers, experience reduced genetic exchange (gene flow) and diversity within a reach-specific population and/or within the metapopulation encompassing multiple river reaches (Jager et al. 2001a). Kootenai River white sturgeon provide an example of this reduced genetic exchange and diversity. This population was post-glacially isolated from downstream Columbia River basin populations by the creation of natural migration barriers approximately 10,000 years ago (Duke et al. 1999, USFWS 1999). Through a possible combination of genetic drift and founder effects, the population developed significant differences in genotype and haplotype frequencies relative to other Columbia River basin populations (Bartley et al. 1985, Setter and Brannon 1992, Anders and Powell 2002).

Theoretically, once populations are isolated, loss of genetic variation and inbreeding may contribute to population declines (Jager et al. 2001b). Additional factors leading to reduced population size (such as overharvest and recruitment limitation or failure) can also reduce within-population genetic variation. Models have been used to predict the effects of fragmentation on population viability and genetic diversity. A simulation experiment involving a hypothetical 200-km river reach examined the theoretical effects of fragmentation on the persistence of a white sturgeon population by employing an individual-based genetic metapopulation model. In this experiment, as the virtual dams were incrementally added, genetic diversity within populations decreased as diversity among populations increased (Jager et al. 2001a). In additional simulation trials involving fragmentation and habitat loss, the resulting loss in genetic diversity among populations occurred faster than with fragmentation alone. The simulation experiment evaluated the effects of varying levels of upstream and downstream migration rates between virtual river segments and emphasized the importance of balanced migration rates.

Genetics techniques offer fisheries managers important tools in understanding the historical and contemporary population structure of different species. They also provide a standardized, reproducible means of evaluation (Anders and Powell 2002). These evaluations may, in turn, enhance our understanding of biological and ecological processes. Such understanding can help identify the most appropriate management, monitoring, and evaluation approaches and techniques. Of these techniques, investigations into the genetic markers in mitochondrial DNA (mtDNA) can provide information about the genetic structure of historical populations and contemporary patterns of gene flow within and among areas or populations (Avise 1994). Geographic distribution and relationships among mtDNA haplotypes of white sturgeon can provide important insight into current and historical population structure (i.e., phylogeography) (Avise et al. 1987) and mechanisms responsible for such structure (Anders and Powell 2002). Such insight into white sturgeon is currently incomplete but remains crucial for successful conservation and management of white sturgeon (Anders and Powell 2002).

In animal populations with few reproductive individuals remaining, the probability of long-term persistence declines, often exponentially, with reductions in effective (Ne) and census (N) population sizes. The concept of effective population size plays an important role in the management of small populations. General guidelines for an ideal population typically identify effective population sizes of 50 and 500 as population benchmarks associated with deleterious

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and potentially irreversible consequences (Thompson 1991, McElhany et al. 2000). Ne values less than 50 may result in inbreeding depression, while numbers less than 500 may result in bottlenecks that reduce adaptive genetic variation (Rieman and Allendorf 2001). These values were derived by assuming a constant population size, random mating (i.e., all individuals have an equal probability of contributing offspring to the next generation), a 50:50 sex ratio, and discrete generations where all adults reproduce once and at the same age (Caballero 1994, Frankham 1995). Although most populations (including white sturgeon) deviate from these “ideal” conditions due to life history strategies (Rieman and Allendorf 2001; Anders 2002, 2003), the general 50/500 rule has been applied to other white sturgeon populations in the Northwest (UCWSRI 2002).

Resource managers and WSTAC members involved in IPC’s relicensing process have expressed concerns regarding potential effects of fragmentation on the current and future genetic integrity of Snake River white sturgeon. Until recently, little empirical genetic information existed for white sturgeon populations. However, recent work has increased our understanding of white sturgeon population genetics in the Columbia River basin, as well as in other river systems in the West (Anders et al. 2000, Anders and Powell 2002). This work included analysis of samples from the Snake River, including material collected from the lower Snake River populations, the Hells Canyon–Lower Granite population, and the Bliss–C.J. Strike population. Population genetic differences, or substructures, were observed between groupings of the various river systems tested with a high degree of spatial separation. For example, when the Snake River fish, pooled as one sample group, were compared with sample groups pooled within the Columbia, Kootenai, Fraser, Nechako, and Sacramento rivers, all paired haplotype frequencies were significantly different (P ≤ 0.05) (Anders and Powell 2002). Although all of the haplotypes observed from the Snake River reaches were also observed in varying degrees in the Columbia River estuary, some haplotypes observed in the estuary were absent from the Snake River samples.

When considering only the Snake River reaches, no apparent genetic substructure was apparent among reaches. Genetic variation among these isolated groups is not unlike the variation seen within them (Table 5) (Anders and Powell 2002). Presumably, we would not expect to see evidence of genetic substructure developing among these Snake River segments due to their artificiality (i.e., the segments are not truly isolated since some downstream migration is known to occur) and the relatively short period of time during which the Snake River has been fragmented relative to the long-lived nature of white sturgeon (P. Anders, S. P. Cramer and Associates, personal communication). Currently, reference to white sturgeon “populations” or “subpopulations” within each of these segments created by dams in the Snake River is simply a convenient way to describe groups of fish in particular geographic areas. The investigations by Anders and Powell (2002) suggested that fragmented reaches within the Snake River areas sampled by IPC could collectively contain one population.

When incorporating population genetics into management options and mitigation measures for Snake River sturgeon populations, the goal should be to at least maintain the variation at levels currently observed in the wild, reproducing populations below Bliss and Hells Canyon dams. Metapopulation-level genetic variability may be lost as a result of translocation or supplementation when populations are genetically distinct. Alternatively, depending on circumstances, such management activities may also increase within-population genetic

23 Snake River White Sturgeon Conservation Plan Idaho Power Company variability. This issue is especially important if sturgeon managers are considering stocking or translocating from more abundant reaches as an option for increasing the effective population size of other reaches. When considering only the genetic aspects of translocation of white sturgeon within the Snake River, the lack of significant differences in white sturgeon haplotype frequencies suggests that, genetically, Snake River white sturgeon constitute a single population or, at least, cannot be separated based on currently applied analytical techniques (Anders and Powell 1999). This understanding makes translocation a viable management option for enhancing populations within some Snake River segments. Translocation of fish among reaches with habitat suitable for reproduction could increase the probability of natural production, potentially enhance genetic diversity, and allow natural selection to operate. Since some downstream migration is known to occur, the greatest genetic benefit to recipient populations is likely to be from downstream sources. Regardless of the source or recipient locations (confined to Snake River reaches), other pertinent nongenetic issues will likely enter into the feasibility evaluation of translocation.

However, it should be noted that the previous conclusions regarding white sturgeon population structure are based solely on mitochondrial DNA analyses. Additional analyses incorporating high resolution bi-parentally inherited nuclear markers (such as microsatellites) are needed to provide a more complete and accurate understanding of white sturgeon population genetics in the Snake River and others systems inhabited by the species. Although primers for these marker systems have been recently developed and published (McQuown et al. 2000, Rodzen and May 2002), they have not yet been used to characterize white sturgeon population genetics in the Snake or Columbia river basins.

3.5. Exploitation

Although the construction of dams and isolation of populations have contributed to the present depressed state of white sturgeon in several reaches of the Snake River, sport fishing has also contributed to reducing numbers and creating unbalanced populations. White sturgeon are extremely vulnerable to overfishing because of their delayed age of maturation and longevity (UCWSRI 2002). As increasing numbers of subadult fish are harvested, too few fish survive to adulthood to spawn and replenish the population. Only very low exploitation rates of 20% or less can be supported by even the healthiest of sturgeon populations, and unproductive populations can sustain no harvest at all (Rieman and Beamesderfer 1990).

Overharvest was believed to have been the primary factor responsible for the decline of white sturgeon in Idaho as early as the late 1930s (Edson 1956). Commercial fishing for sturgeon in Idaho began in the mid-1890s and lasted for approximately 48 years. Sport and commercial sturgeon fishing was unregulated in Idaho prior to 1943 (Hanson et al. 1992). By the late 1930s, four dams had been built on the Snake River between 1901 and 1937 (Swan Falls, Shoshone Falls, Lower Salmon Falls, and Upper Salmon Falls), although they impounded only about 4% of the river. Beginning in 1943, fishing regulations were implemented. Increasingly restrictive sport regulations followed until 1970, when a catch-and-release fishery program was adopted for the entire Snake River in Idaho. While little historical information is available for Idaho white sturgeon populations, past harvest and abundance trends are believed to be similar to those in the Columbia River (USEPA 2002). Historic overfishing collapsed sturgeon populations

24 Idaho Power Company Snake River White Sturgeon Conservation Plan in the lower Columbia, Fraser, and Sacramento–San Joaquin rivers around the turn of the century (UCWSRI 2002). Populations in each of these areas were severely overfished within 10 to 20 years by unregulated, targeted, commercial exploitation (Semakula and Larkin 1968, Galbreath 1985). Cochnauer (1983) suggested that the spawning population in the Snake River would gradually decline with exploitation rates of 0.05 to 0.10 for fish 125–183 cm long, assuming estimates of total instantaneous mortality rates of 0.06 to 0.27 from observed data. The Hells Canyon–Lower Granite sturgeon population probably experienced exploitation rates of 0.30 (for fish 10 to 20 years old) in the mid-1970s (unpublished data collected by Coon et al. 1977 and presented by Lukens 1985).

There is still high demand for sturgeon among recreational anglers, even with the present sport fishing catch-and-release regulations in the Snake River. A 1999 recreation survey conducted in the Hells Canyon National Recreation Area found that 27% of anglers visiting the area were specifically targeting white sturgeon, and of those, 57% were catching at least one sturgeon (Brown 2002). While catch-and-release regulations have been enforced throughout the Snake River as a method for conserving white sturgeon stocks, little is known about the biological effects of repeated catch-and-release angling to white sturgeon. Angling can be one of the most severe forms of exhaustive exercise that a fish experiences (Booth et al. 1995). Several studies on different species of fish have shown that exhaustive exercise (including that due to angling), results in a variety of severe physiological disturbances such as altered reproductive performance and delayed mortality (Nelson 1998, Lambert and Dutil 2000, Schreer et al. 2001). For instance, during July 2001, two sturgeon carcasses were found in the C.J. Strike tailrace. These sturgeon had died as a result of hooking mortality. The number of hooks ingested by these two fish ranged from 3 to 20, with several hooks puncturing the esophagus and intestinal tracts. Because anglers increasingly recognize that “large” sturgeon can readily be hooked in the C.J. Strike tailrace, this area has become a very popular area to fish for sturgeon on the Snake River. Angler catch records below C.J. Strike Dam indicate that anglers spent 3,675 days during 1994 to catch 1,550 sturgeon, making this the most intensively fished section for sturgeon in Idaho (IDFG 1995).

4. STATUS OF SNAKE RIVER WHITE STURGEON

4.1. Shoshone Falls–Upper Salmon Falls Reach

4.1.1. Project and Reach Description

Shoshone Falls (RM 614.7), located near the town of Twin Falls, Idaho, is a historical natural migration barrier to migratory fish including white sturgeon. IPC owns and operates a hydroelectric facility at the falls. This facility was the first hydroelectric power plant built in southern Idaho’s Magic Valley. The Greater Shoshone and Twin Falls Water Power Company initially constructed the plant between 1901 and 1909. IPC acquired the plant in 1916 when the company was formed. The current structure at Shoshone Falls includes a diversion dam and a powerhouse with three generators, which have a total generating capacity of 12.5 megawatts

25 Snake River White Sturgeon Conservation Plan Idaho Power Company

(MW). The project is operated as run-of-river (ROR) under all flow conditions. River flows in excess of the plant’s 950-cfs hydraulic capacity are passed via the project’s overflow dam sections and spill gates.

The Snake River downstream of Shoshone Falls is free flowing for approximately 28.6 miles before entering Upper Salmon Falls Reservoir (Figure 8). Upper Salmon Falls Dam (RM 581.4) impounds water for 4.7 miles, has a reservoir surface area of 50 acres, and has a median retention time of 1.3 hours. This section of the Snake River from Milner Dam (located 24.8 miles upstream of Shoshone Falls) downstream to King Hill (RM 547) lies within a deeply incised (19.8–90 m) canyon cut through basalt rock with overlying sedimentary deposits. During the Pleistocene Epoch, scouring flows from the ancient Lake Bonneville created the canyon approximately 13,500 to 15,000 years ago. The flood waters deposited sandbars, gravel, and boulders more than 3 m in diameter (USEPA 2002). The average stream gradient from Milner Dam to King Hill is about 3.4 m/km. However, this statistic alone provides an incomplete picture of the river between Shoshone Falls and Upper Salmon Falls dams since the majority of elevational drops in this reach happen at a few impressive falls and steep rapids. Some of these falls and rapids are barriers to migrating fish during low flows. The most notable falls within this reach are Shoshone Falls (65 m) and Auger Falls, a cascade that drops 11.8 m. Sections of river between the falls have lower velocities characteristic of lower gradients.

The geology and water management practices in this area of the basin make the hydrology in this segment of the Snake River very complex. Flows over Shoshone Falls are largely dependent on water released past Milner Dam, constructed in 1905. The average annual flow below Milner Dam is 3,200 cfs. However, over the period from 1980 to 1989, flows from Milner Dam were less than 99 cfs 10% of the time (Clark 1994). According to state law, the Milner Dam project may divert as much as 100% of Snake River flows during the summer irrigation months into canal systems designed to deliver water throughout the region. The major water users through this region of the state depend on these discharges for agriculture and aquaculture activities. Milner Dam was developed primarily to divert stored water from upstream reservoirs for irrigators in the Magic Valley region, and it generates electricity when excess water is available. A percentage of this diverted water eventually returns to the Snake River by way of tributaries, groundwater discharge, and irrigation returns.

Downstream of Milner Dam, spring discharges from the Snake River Plain Aquifer recharge the river (Figure 9). Numerous springs, most notably the Thousand Springs, reliably contribute about 1,190 cfs to the Snake River. During the irrigation season when most of the river is diverted, the springs are the primary source of river flow. In addition to the major spring complexes, eight major tributaries (six of which are creeks) enter the Shoshone Falls–Upper Salmon Falls reach of the Snake River: East Perrine Coulee, Rock Creek, Cedar Draw Creek, Mud Creek, Deep Creek, Salmon Falls Creek, Billingsley Creek, and the Malad River. The total contribution of these tributaries averages 1,695 cfs, with the major contribution coming from the Malad River (USEPA 2002).

4.1.2. Population Status

During a cooperative survey conducted in 2001, IDFG and IPC captured a total of 251 white sturgeon (including 29 recaptures) in the Shoshone Falls–Upper Salmon Falls reach. A total of

26 Idaho Power Company Snake River White Sturgeon Conservation Plan

10,378 hours of setline and 29 hours of gill net effort were expended, resulting in catch per unit efforts (CPUE) of 0.02 and 0.65 fish/hour respectively. No sturgeon were captured during limited rod-and-reel (also referred to as angling) sampling (n = 36 hours) (Table 6). The majority of sturgeon were sampled between Auger Falls (RM 606.7) and RM 600.5 (Figure 10 and Figure 11). Of the fish sampled, 6% (n = 13) were of wild origin and 94% (n = 209) were hatchery- propagated sturgeon. The abundance of white sturgeon (hatchery and wild) greater than 70 cm in the Shoshone Falls–Upper Salmon Falls reach was estimated at 777 fish (95% confidence interval [CI] 574–1,201) or 18 fish/km (Table 7). Based on the population estimate and ratio of wild to hatchery sturgeon in the sample, the total number of wild sturgeon (greater than 70 cm) remaining in the population was estimated at 47 fish (Lepla et al. 2002).

Hatchery sturgeon ranged in length from 53 to 205 cm TL, and wild sturgeon ranged from 66 to 267 cm TL. The size composition of hatchery (wild) sturgeon sampled with setline gear ranged from 19% (0.0%) of the fish measuring less than 92 cm TL, 70.2% (0.4%) measuring between 92 and 183 cm TL, and 2.0% (8.4%) measuring greater than 183 cm TL. Size composition of hatchery (wild) sturgeon sampled with gill net gear ranged from 62% (11%) of the fish measuring less than 92 cm TL, 21% (0.0%) measuring between 92 and 183 cm TL, and 0.0% (6.0%) measuring greater than 183 cm TL (Figure 12a and Figure 13a).

Growth rates and condition factor of sturgeon within this reach appear quite good relative to other Snake River sturgeon populations. Length–weight relationships for sturgeon less than 120 cm overlapped considerably across all Snake River reaches but tended to indicate that larger sturgeon in the Shoshone Falls–Upper Salmon Falls and Bliss–C.J. Strike reaches were generally heavier than sturgeon in reaches below C.J. Strike Dam (Figure 14). The growth rates of sturgeon from the 1988, 1990, and 1993 year classes in the Shoshone Falls–Upper Salmon Falls reach have averaged about 9.6 to 8.7 cm per year (Figure 15) and appear similar to growth rates observed in wild sturgeon populations below Bliss and Hells Canyon dams (Figure 16). The condition factor (or mean relative weight) of white sturgeon within the Shoshone Falls–Upper Salmon Falls reach are also average (100%, Table 8), based on the standard developed for white sturgeon by Beamesderfer (1993). Survival and mortality rates are comparable to those observed in other Snake River populations. Based on the known ages of recaptured hatchery fish from three year classes, Lepla et al. (2002) estimated survival (S) for Shoshone Falls–Upper Salmon Falls sturgeon aged 8 to 13 years old to be 0.88, which yielded a total annual mortality (A) of 0.12 (Table 9). Twelve hatchery sturgeon and 9 wild sturgeon were also surgically examined to determine sex and stage of maturity. Of those examined, 7 were females, 10 were males, and 4 were of unknown sex with no gonad material visible. The stages of maturity for female sturgeon of hatchery (wild) origin comprised 2 (0) previtellogenic females, 2 (2) early vitellogenic females, and 0 (1) ripe females. As for stages of maturity for male sturgeon of hatchery (wild) origin, 3 (3) males were nonreproductive and 3 (1) were reproductive (Lepla et al. 2002).

The white sturgeon population in the Shoshone Falls–Upper Salmon Falls reach currently ranks as the fourth largest sturgeon population (based on the 95% CI) in the Snake River. However, it is important to emphasize that 94% of the population is composed of hatchery-propagated fish. A total of 1,208 white sturgeon were stocked in the Shoshone Falls–Upper Salmon Falls reach from 1989 to 1991 and in 1994 and 1997 (Table 10). These stocking efforts have apparently been successful based on the current abundance estimate, growth, and survival rates of the hatchery fish. However, the latest investigation by Lepla et al. (2002) also indicates that wild sturgeon

27 Snake River White Sturgeon Conservation Plan Idaho Power Company remain few in number and show no positive change in abundance or stock structure since the 1980–1981 IDFG survey by Lukens (1981). Lukens reported capturing 14 sturgeon (which included catches from project sampling efforts and local sportsman) ranging in length from 102 to 223 cm TL. The absence of small wild fish during the 1980–1981 survey (Lukens 1981) and the capture of only two wild sturgeon (measuring 66 and 77 cm) in the 2001 survey (Lepla et al. 2002) indicate that little natural recruitment has occurred over the last 20 years (Figure 17).

Lukens (1981) suggested that the lack of recruitment was probably a result of low spawner abundance coupled with low spawning frequency. Considering that it can take up to 12 years for a sturgeon to mature and spawn for the first time, after which it may spawn once every 3 to 11 years, it would be difficult for a small number of adult sturgeon to rebuild or sustain a population. With few adults remaining and variable reproductive readiness occurring between the sexes, the opportunities for reproduction would likely be infrequent. In addition, too few fish in the population would also reduce the likelihood of mating pairs forming when environmental conditions were favorable for recruitment. An ecological risk assessment of the middle Snake River by the U.S. Environmental Protection Agency (USEPA) found that impairment values were generally high for all life stages of white sturgeon in this reach. In particular, survival estimates were lowest for life stages from spawning through larval development because of low river flows, high temperatures, and the loss of dynamic spawning and rearing habitats (USEPA 2002).

As discussed above, river flows passing over Shoshone Falls are significantly affected by upstream irrigation diversions and depend largely on the amount of water released at Milner Dam. The median flows recorded over Shoshone Falls (as measured at Kimberly, Idaho) and near the middle of the reach (Buhl, Idaho) during the months when white sturgeon spawning, incubation, and larval life stages of development in the middle Snake River would typically occur (March–June) are 1,970 and 4,349 cfs, respectively (Figure 18). In comparison, the March–June median flow measured at the King Hill gauge in the Bliss–C.J. Strike reach (for the period of record from 1905 to 2000) is 10,300 cfs. However, years with high snow pack may still produce high-flow conditions favorable for recruitment. Two wild sturgeon captured in the 2001 survey were of a size and estimated age suggesting that some spawning probably occurred in 1996 and 1997 (Lepla et al. 2002). Both of these years were considered high water years with mean daily flows (during suitable spawning temperatures) ranging from 4.64 to 19.9 kcfs in 1996 and from 8.63 to 17.8 kcfs in 1997.

Although having too few spawners in the population when environmental conditions are favorable may have contributed to the past poor recruitment trends, spawner limitations may soon be alleviated as hatchery white sturgeon approach maturity. Results from the 2001 stock assessment found that some hatchery females were approaching first maturity and several males were already displaying reproductive readiness (Lepla et al. 2002). Based on the population’s demographics in 2001, an increasing number of hatchery fish will likely mature within the next five years or so.

28 Idaho Power Company Snake River White Sturgeon Conservation Plan

4.2. Upper Salmon Falls–Lower Salmon Falls Reach

4.2.1. Project and Reach Description

The Upper Salmon Falls–Lower Salmon Falls reach is part of the three Mid-Snake projects, made up of Upper Salmon Falls, Lower Salmon Falls, and Bliss dams. The Upper Salmon Falls Project consists of two diversion dams and two power plants, A and B. IPC built the Upper Salmon Falls Plant A in 1937. This plant is located on the Snake River near Hagerman, Idaho, at RM 579.6 (Figure 19). The plant includes a diversion structure and two generators with a total nameplate generating capacity of 18 MW. The Upper Salmon Falls Plant B, located at RM 580.8, lies 1.2 miles upstream of Plant A. It was built in 1947 and includes a diversion structure (RM 581.4) and two generators with a total nameplate generating capacity of 16.5 MW. The short section of the Snake River between Plants A and B has no storage capacity and is wholly controlled by discharge from Plant B. The Upper Salmon Falls Project is operated as a ROR facility under all flow conditions.

The original Lower Salmon Falls Power Plant (RM 573) was built in 1910 by the Greater Shoshone and Twin Falls Water Power Company. IPC acquired the plant in 1916, when the company was formed, and rebuilt it in 1949. Lower Salmon Falls Dam forms a 748-acre reservoir above the plant, which can hold up to 10,900 acre-feet of water, with a median retention time of 18.3 hours. The 7.8-mile reach of the Snake River between these two projects is almost entirely made up of reservoir habitat, except for a 0.6-mile bypass at Dolman Island. Flows in these braided channels are often less than 500 cfs. Over a 24-hour period, project releases equal inflow to the reservoir (FERC 2002a). Alluvial deposits of unconsolidated clay, silt, and sand are common (USEPA 2002). Billingsley Creek is the only major tributary to this reach; it adds about 27 to 48 cfs, primarily of spring water.

4.2.2. Population Status

The presence of sturgeon in the Upper Salmon Falls–Lower Salmon Falls reach is questionable. During the 1979–1981 period, IDFG expended 78 hours of angling and 64 hours of setline effort and found no sturgeon (Lukens 1981). Lukens (1981) concluded that no spawning habitat was available for white sturgeon in this reach.

In addition to the lack of spawning habitat, shorter reaches in the Snake River also appear more susceptible to downstream export of white sturgeon than longer reaches: over time, the population erodes as fish move to downstream areas. A common observation in short reaches of both the Mid-Snake and Hells Canyon complexes has been little or no detectable presence of sturgeon recruitment. PVA simulations also suggested that larval export was limiting recruitment in shorter segments of the Snake River (Jager et al. 2001b).

Part of white sturgeon ecology includes dispersal of the early life stages from spawning sites to areas suitable for feeding and rearing (see section 2 about the biology of white sturgeon). The tendency for early life stages to disperse over wide areas lends support to the assumption that shorter river segments would likely experience high levels of downstream export of white sturgeon and may no longer be capable of supporting large populations.

29 Snake River White Sturgeon Conservation Plan Idaho Power Company

4.3. Lower Salmon Falls–Bliss Reach

4.3.1. Project and Reach Description

The original Lower Salmon Falls Power Plant was built in 1910 by the Greater Shoshone and Twin Falls Water Power Company. IPC acquired the plant in 1916, when the company was formed, and rebuilt it in 1949. The Lower Salmon Falls Project has a total nameplate generating capacity of 60 MW and includes a 983-foot-long dam and a powerhouse with four generators. This project is operated as a load-following facility: reservoir storage is used to shape power output to follow hourly changes to system load demand. River flows in excess of the power plant’s 17,200-cfs hydraulic capacity are passed over the overflow and gated spillway sections of the dam.

The Snake River below Lower Salmon Falls Dam (RM 573) is relatively high gradient and free flowing for 8 miles before entering Bliss Reservoir (Figure 19). Bliss Dam (RM 560.3), which serves as the lower bound for this segment, impounds water for 5 miles and covers 255 acres. The storage capacity of the pool is 8,415 acre-feet of water, with a median retention time of 11 hours. The geomorphology within this segment varies from alluvial deposits of unconsolidated pebbles, cobbles, and boulders in basaltic sand in the upstream portion to some similar alluvial deposits in some lacustrine deposits of clay nearer the lower section toward Bliss Dam (USEPA 2002). The Malad River enters the Snake River at RM 571.4 within the free- flowing section. It is the largest tributary to the Lower Salmon Falls–Bliss reach. Discharge in the Malad River comes principally from Malad Springs, a collection of springs within and adjacent to the riverbed. The springs provide a dependable flow of 1,100 to 1,200 cfs to the Malad River.

4.3.2. Population Status

Two studies have concluded that few wild sturgeon remain in the Lower Salmon Falls–Bliss reach. Lukens (1981) reported capturing 11 wild sturgeon in the Lower Salmon Falls tailrace with 2,103 hours of angling and 3,267 hours of setline effort. Lepla and Chandler (1995b) captured a total of 41 white sturgeon (including 3 recaptures) with 6,198 hours of setline, 247 hours of gill net, and 2 hours of angling effort (Table 6). Similar to Lukens’ survey, Lepla and Chandler found that the majority (76%) of fish and highest catch rates (0.02 fish/hour) occurred in the tailrace of Lower Salmon Falls Dam (Figure 10 and Figure 11). Of the fish sampled, 5 were wild and 33 were hatchery-propagated sturgeon. Wild sturgeon sampled by setlines and gill nets ranged from 60 to 125 cm TL, and hatchery-reared sturgeon ranged from 40 to 133 cm TL (Figure 12b and Figure 13b). The condition factor of sturgeon appears to have declined somewhat between the 1981 and 1993 surveys, although relative weights were still similar to those observed in several other Snake River sturgeon populations (Table 8).

A total of 2,560 yearling hatchery sturgeon were stocked below Lower Salmon Falls Dam during 1989, 1991, and 1994 (Table 10). However, stocking efforts below Lower Salmon Falls Dam were not as successful as those in the Shoshone Falls–Upper Salmon Falls reach. About twice as many fish were stocked in this segment, yet few fish were collected during the 1992–1993 survey. Based on observed survival (S = 0.88) and average growth rates (7.3 cm/year) of

30 Idaho Power Company Snake River White Sturgeon Conservation Plan hatchery sturgeon in the Shoshone Falls–Upper Salmon Falls reach, more fish should have been available for capture.

In 1996, IPC sampled the tailrace of Lower Salmon Falls Dam to obtain blood samples from wild sturgeon for genetic evaluations. A total of 36 sturgeon (with 2 recaptures) were sampled, including 5 wild fish ranging in length from 32 to 205 cm TL and 29 hatchery fish ranging in length from 53 to 148 cm TL. Two sturgeon in the sample were not determined to be wild or hatchery because of malfunctions with the equipment that read the 125-kHz Passive Integrated Transponder (PIT) tags. Assuming that these fish were wild and not hatchery sturgeon with undetectable PIT tags, the size of the smallest wild sturgeon suggested that some successful spawning may have occurred in 1995. A comparison of length frequency histograms from the last three sampling efforts (1980–1981, 1992–1993, and 1996) indicates that natural recruitment within this reach is sporadic and not at levels needed to maintain the population (Figure 20).

While operations of the Lower Salmon Falls Project can affect sturgeon habitats, these operations do not appear to be the primary factor responsible for the poor trend in recruitment. A times-series analysis of modeled operations3 at Lower Salmon Falls Dam showed that project operations can reduce the weighted usable area (WUA) of spawning run habitat when compared with ROR conditions in low- and normal-flow years (Brink 2000). In the low- and normal-flow years, we estimate that project operations could produce a minimum of 65 and 55% of the white sturgeon spawning habitat that would be present under ROR operations. Our index of spawning habitat WUA was not impacted during the high-flow year (1997) because operations did not differ from ROR conditions (Figure 21). Changes in habitat (as measured by WUA) for other modeled life stages (juvenile and adult) as a result of project operations were minimal; generally project operations provided greater than 90% of the habitat that would be produced under ROR operations (Figure 22 and Figure 23).

The low abundance of both naturally produced (Lukens 1981) and hatchery-stocked sturgeon in the Lower Salmon Falls–Bliss reach (Lepla and Chandler 1995b) suggests that suitable habitat for population growth and maintenance is limited. Study results from IFIM (i.e., instream flow incremental methodology) and population modeling (PVA) have suggested that suitable habitats for rearing are limited (Brink 2000) and that “short” reach lengths may result in a higher propensity for downstream export of sturgeon than longer reaches of the Snake River, particularly during early life stage development (Jager et al. 2001a). A common observation in short reaches of both the Mid-Snake projects (Upper Salmon Falls, Lower Salmon Falls, and Bliss dams) and the HCC (Brownlee, Oxbow, and Hells Canyon dams) has been little or no detectable presence of sturgeon recruitment.

3 The CHEOPS model used assumed that load following would occur at all times when inflows were between proposed minimum flow and the plant’s hydraulic capacity. However, IPC does not operate the Lower Salmon Falls Project to load follow at all times, even though the current license does not restrict IPC from doing so.

31 Snake River White Sturgeon Conservation Plan Idaho Power Company

4.4. Bliss–C.J. Strike Reach

4.4.1. Project and Reach Description

Bliss Dam (RM 560.3), constructed in 1941, is a 364-foot-long by 84-foot-high concrete gravity dam. The powerhouse contains three generators with a total nameplate generating capacity of 75 MW. The Bliss Project is typically operated as a load-following facility in tandem with the upstream Lower Salmon Falls Project. Changes in releases at Lower Salmon Falls Dam translate into changes in inflow to Bliss Reservoir in less than one hour. Over a 24-hour period, project releases are equal to inflow to the reservoir. Bliss Dam, in conjunction with the Lower Salmon Falls and C.J. Strike projects, supplies short-term load-following generation during anticipated or emergency outages (FERC 2002a).

The Snake River below Bliss Dam extends 66 miles and encompasses three major types of habitat (Figure 24). The upper 13 river miles of this reach, between Bliss Dam and King Hill (RM 547), is located in a narrow river corridor that creates several large rapids and deep, turbulent run and pool habitats. This canyon section has a gradient of 1.15 m/km (6.2 ft/mile). The riverbanks in this area are typically steep and covered with boulders. After leaving the higher-gradient canyon section near King Hill, the character of the river transforms into that of a low-gradient, shallow, meandering river with multiple braided channel sections and run-type habitats. This lower-gradient section (0.33 m/km) continues until the river enters C.J. Strike Reservoir at RM 518. This low-gradient section supports abundant summertime macrophyte growth in the shallower areas and harbors a few pools 8 to 10 m deep and one pool greater than 20 m deep (Cochnauer 1983).

The remaining 24 miles of this reach lie within C.J. Strike Reservoir, which has a surface area of approximately 7,500 acres and a total capacity of 240,000 acre-feet. The mean depth of the reservoir is 10.1 m, and the maximum depth is 42.4 m. The retention time of the reservoir, based on median inflows, is 15.6 days. C.J. Strike Reservoir is not used to store water on a seasonal basis, but it is fluctuated to meet changing power demands over the course of the day. Myers and Pierce (1997) reported that the reservoir can, at times, experience very low levels of DO (< 2 mg/l) in the lower 8 miles of the pool. The reservoir terminates downstream at C.J. Strike Dam (RM 494), which is located east of Grand View, Idaho.

Few tributaries within this segment contribute appreciable amounts to overall river flows. Clover Creek (RM 547.6) displays highly variable flow but annually discharges an average of about 140 cfs to the Snake River upstream of King Hill. Sailor Creek enters the Snake River at RM 528.5 and likewise contributes highly variable flows. The Bruneau River is the largest tributary and enters C.J. Strike Reservoir after draining approximately 6,810 km2 of southern Idaho and northern Nevada. Its mean annual discharge is 388 cfs, with an average spring discharge of 825 cfs and an average fall discharge of 102 cfs (IDEQ 2000). The Bruneau River aids in forming the southern arm of C.J. Strike Reservoir, a shallower constituent of the impoundment connected via a deep canyon section of the original Bruneau River channel.

32 Idaho Power Company Snake River White Sturgeon Conservation Plan

4.4.2. Population Status

The white sturgeon population between Bliss and C.J. Strike dams is the largest population in the Snake River above Hells Canyon Dam. Two population assessments of sturgeon were conducted in the Bliss–C.J. Strike reach between 1979 and 1993. During the 1979–1981 surveys, IDFG collected a total of 905 white sturgeon with 9,059 setline and 10,329 angling hours of effort; they estimated the population’s abundance at 2,192 fish (Cochnauer 1983). A second stock assessment by IPC from 1991 to 1993 resulted in the capture of 775 white sturgeon, including 106 recaptures, with 23,177 setline, 703 gill net, and 13.2 angling hours of sampling effort (Table 6) (Lepla and Chandler 1995a). Of these fish, 307 were captured with setlines; 450, with gill nets; and 18, with rod and reel. The latest survey estimated the population size at 2,662 fish or 30 fish/km (Table 7), suggesting that the abundance of sturgeon in this segment may have increased slightly since the 1979–1981 survey.

During the 1991–1993 survey, the majority of sturgeon (84%) were captured in C.J. Strike Reservoir, with the highest catch rates occurring between RM 498 and 514. Catch rates in the river were generally higher near the upper end of the reach (Figure 10 and Figure 11). In addition to wild sturgeon captures, 28 hatchery sturgeon were also collected. Prior to the IPC survey, 1,200 hatchery-propagated sturgeon were stocked in the Bliss–C.J. Strike reach in 1989 (Table 10). Captured sturgeon ranged in length from 44 to 334 cm TL for wild fish and 47 to 94 cm TL for hatchery fish. A length frequency histogram of wild (hatchery) sturgeon collected by setlines showed 1.5% (3.5%) of the fish were less than 92 cm TL, 40% (0%) were between 92 and 183 cm TL, and 55% (0%) were greater than 183 cm TL (Figure 12c). Wild (hatchery) sturgeon sampled with gill nets ranged from 8% (7%) less than 92 cm TL, 71% (1%) between 92 and 183 cm TL, and 13% (0%) greater than 183 cm TL (Figure 13c).

Length–weight and von Bertalanffy growth (VBG) relationships indicated that sturgeon in the Bliss–C.J. Strike reach have some of the highest growth rates observed in the Snake River, particularly for the larger adults (Figure 14 and Figure 16). Based on the VBG regression line, growth rates averaged 10 cm/year for sturgeon less than 92 cm TL, 8 cm/year for mid-sized sturgeon between 92 and 183 cm TL, and 3.8 cm/year for larger sturgeon greater than 183 cm TL. This predicted growth rate is supported by the observed growth rates from recaptured sturgeon in the Bliss–C.J. Strike reach. Sturgeon at large between 313 to 3,268 days increased in length an average of 6.2 cm/year for mid-sized sturgeon (92–183 cm) and 3.9 cm/year for larger sturgeon greater than 183 cm (Figure 25). Cochnauer (1983) suggested that white sturgeon in the middle Snake River exhibited higher growth rates due to annually moderated water temperatures from the area’s numerous groundwater springs.

Mean relative weights of sturgeon captured during the 1979–1981 and 1991–1993 surveys indicated that sturgeon in this reach were at or near average condition (Table 8), based on the standard developed by Beamesderfer (1993). Statistical comparison of the mean relative weights showed that fish condition had not declined (P > 0.05) between surveys. Mortality rates of fish ranged from 0.06 to 0.13 and were similar to those observed in other Snake River populations (Table 9). The percentage of gravid females in a given year, or reproductive potential (13%) of white sturgeon in the Bliss–C.J. Strike sturgeon population, appears similar to the potential (10%, Apperson and Anders 1990) expected in a typical white sturgeon population. Female sturgeon were in various stages of maturation, ranging from 36% (28) previtellogenic, 28%

33 Snake River White Sturgeon Conservation Plan Idaho Power Company

(22) early vitellogenic, 14% (11) late vitellogenic, 13% (10) ripe, 4% (3) spent, and 6% (5) previtellogenic with attritic oocytes. The annual number of spawning females in the population was estimated at 19 (95% CI 1–41) fish (Lepla and Chandler 1995a).

Noticeable changes in recruitment levels between the 1979–1981 and 1991–1993 surveys have been of particular value in the Bliss–C.J. Strike stock assessments. Juvenile white sturgeon less than 92 cm TL made up about 64% of the catch during 1979–1981. During the 1991–1993 survey, numbers of wild juvenile sturgeon dropped to only 3.5 to 8%. These estimates are based on setline and gill net length frequencies. This decline in the proportion of young white sturgeon corresponded with an unusually prolonged period of drought, with eight consecutive years (1987–1994) of below-normal river flows in the Snake River basin. Concern over the downward trend in recruitment prompted a third survey by IPC in 2000. This latest survey showed that the number of wild juvenile white sturgeon (less than 92 cm TL) had increased from less than 8% to 45% of the catch (Figure 26). An increase in abundance of juvenile sturgeon appeared to be a result of more favorable hydrologic conditions during the spawning months with normal and above-normal spring flows (1996–1999) (Figure 27). However, the estimated age structure of the sturgeon population sampled in 2000 also indicated that recruitment was especially poor during below-normal water years when aggressive load following occurred (1988, 1989, and 1990) at Bliss Dam (Figure 28 and Figure 29). In contrast, higher recruitment levels occurred in years with similar hydrology but limited or no load following during the sturgeon spawning season (1992, 1993, and 1994). A time-series analysis showed that project operations at Bliss Dam primarily affected the early life stages during low- and normal-flow years. In low- and normal- flow years, project operations4 could produce a minimum of 79, 20, and 30%, respectively, of the white sturgeon spawning, incubation, and larvae habitat that would be present under ROR operations. WUA analysis suggests that, during high-flow years, habitat for spawning, incubation, and larval life stages was not impacted by modeled project operations since WUA was 100% of ROR conditions (Figure 30 to Figure 32) (Brink and Chandler 2000). Habitat WUA for all other life stages (YOY, juvenile, and adult) was not affected by modeled project operations and was generally near 100% of the habitat that would be produced under ROR conditions. Study results showed that modeled operations reduced WUA by less than 2% across low- and normal-flow years, whereas no reduction in WUA occurred during high-flow years (Figure 33 to Figure 35) (Brink and Chandler 2000).

4.5. C.J. Strike–Swan Falls Reach

4.5.1. Project and Reach Description

C.J. Strike Dam was constructed in 1952 at RM 494, just below the confluence of the Snake and Bruneau rivers (Figure 36). The project consists of a 3,220-foot-long earthfill dam and concrete powerhouse with three vertical fixed-blade turbine generators capable of generating 82.8 MW. The project operates in a “block load” (one, two, or three units) mode to meet daily system

4 The CHEOPS model used assumed that load following would occur at all times when inflows were between proposed minimum flow and the plant’s hydraulic capacity. However, IPC does not operate the Bliss Project to load follow at all times even though the current license does not restrict IPC from doing so.

34 Idaho Power Company Snake River White Sturgeon Conservation Plan power demands. Units are brought online and loaded to their peak efficiency or taken offline, as demand dictates. Generally, two or three units (depending on inflow) are operated during high- demand periods, and a single unit is operated during periods of lower demand. Daily tailwater fluctuations can vary up to 4 ft; however, 70% of the time, daily tailwater fluctuations are 3 ft or less (FERC 2002b).

The Snake River downstream of the C.J. Strike Project flows about 25.2 miles before entering Swan Falls Reservoir. This reach is relatively low gradient and consists primarily of shallow runs with simple island complexes and few deep runs or pools (Anglin et al. 1992). Nearly the entire length of this segment borders land used primarily for a variety of agricultural practices such as farming, grazing, and confined feeding operations. Swan Falls Dam (RM 458) operates as a run-of-river project, impounds 1,525 acres, holding up to 7,425 acre-feet of water, and has a median retention time of 9.8 hours. The Swan Falls Dam impounds water for nearly 10.8 miles, with an average pool depth of about 2 m. Water quality in the C.J. Strike–Swan Falls reach is affected by point and nonpoint sources, including irrigated agriculture, grazing, confined animal feed operations adjacent to the project area, and upstream sources from the middle Snake River above C.J. Strike Reservoir (Myers and Pierce 1997).

4.5.2. Population Status

From 1994 to 1996, IPC collected 654 white sturgeon (including 324 recaptures) from 33,747 setline, 448 gill net, and 129 angling hours of effort (Table 6) (Lepla and Chandler 1997). The majority (95%) of sturgeon were captured within the upper 8 miles of the reach between C.J. Strike Dam and RM 486. Catch rates from RM 486 downstream to Swan Falls Dam were poor: only one sturgeon was sampled in Swan Falls Reservoir (Figure 10 and Figure 11). The high concentration of sturgeon in the vicinity of the tailrace may be related to increased foraging opportunities at C.J. Strike Dam. The abundance of sturgeon in the C.J. Strike–Swan Falls reach was estimated at 726 fish (95% CI 473–1565), roughly one-third the size of the upstream Bliss– C.J. Strike sturgeon population (Table 7).

Of the captured sturgeon, 328 fish were wild and two fish were of hatchery origin. Wild sturgeon ranged in length from 71 to 253 cm TL, and hatchery sturgeon measured 76 and 92 cm TL. Length frequency histograms showed that the sturgeon population below C.J. Strike Dam comprised mostly mid-sized and large sturgeon. Wild (hatchery) sturgeon collected by setlines showed 6% (0.4%) of the fish were less than 92 cm TL, 58.6% (0%) were between 92 and 183 cm TL, and 35% (0%) were greater than 183 cm TL (Figure 12d). Mid-sized and large sturgeon also dominated the gill net histogram, with 16.4% (0.6%) less than 92 cm TL, 68% (0%) between 92 and 183 cm TL, and 15% (0%) greater than 183 cm TL (Figure 13d). Rod-and- reel sampling produced similar results: fish ranged between 108 and 211 cm TL.

The VBG relationships indicated that growth rates of sturgeon below C.J. Strike Dam compared favorably with those observed for sturgeon in the Bliss–C.J. Strike reach (Figure 16). However, length–weight relationships showed that large sturgeon below C.J. Strike Dam were lighter than fish of similar size upstream in the Bliss–C.J. Strike reach (Figure 14). Mean relative weight for sturgeon sampled in the C.J. Strike–Swan Falls reach was below average (88%) but similar to condition factors reported for sturgeon sampled in other riverine segments of the Snake River (Table 8). Annual mortality of sturgeon below C.J. Strike Dam was comparable with mortality

35 Snake River White Sturgeon Conservation Plan Idaho Power Company estimates from other Snake River sturgeon populations (Table 9). Powerhouse-related mortalities have occurred at C.J. Strike Dam. Since 1996, at least five sturgeon mortalities have been reported in the tailwaters of C.J. Strike Dam as a result of blade-strike injury. It became apparent that some sturgeon were entering the draft tube (where outflows from turbines enter the tailrace) when a turbine was offline. Sturgeon were injured as the unit returned online, either by blade strikes or by contact with concrete dividers as they exited the draft tube. In 2000, IPC began using compressed air blasts prior to unit start-ups in an effort to “clear” sturgeon away from the turbine blades. No further powerhouse-related mortalities have been reported since this practice was initiated.

Ninety-one sturgeon (greater than 150 cm TL) were surgically examined to determine sex and stage of maturity. Although the ratio of males to females was nearly one to one (50.5% females to 49.5% males), only a few females (4%) were in reproductive readiness. By comparison, 13% of the females below Bliss Dam and 11% of the females below Hells Canyon Dam were reproductive during IPC surveys. The annual number of spawning females in the population was estimated at seven (95% CI 4–17) fish (Lepla and Chandler 1997).

Survey results indicated that some downstream movement of mid-sized and large sturgeon had occurred from the Bliss–C.J. Strike reach. Six sturgeon (four wild and two hatchery) that had originally been sampled in the Bliss–C.J. Strike reach were recaptured below C.J. Strike Dam. Most of the sturgeon were relatively large (121–211 cm TL), suggesting that they probably passed the project during spill events. Based on the recovery of these fish and a number of telemetered sturgeon in the Bliss–C.J. Strike reach, IPC estimated that 2% of the Bliss population was migrating downstream annually (IPC unpublished data).

Of particular concern, the 1994–1996 survey highlighted that spawning was largely unsuccessful below C.J. Strike Dam based on the low abundance (8%) of sturgeon less than 92 cm TL. A follow-up survey was conducted in 2001 to evaluate recruitment levels in response to normal and above-normal flows (1996–99) in the middle Snake River. Despite the occurrence of high-flow years, no increase in the number of small sturgeon was observed (Figure 37c). These results contrasted with post-drought recruitment trends observed upstream in the Bliss–C.J. Strike population where numbers of small sturgeon increased from 8% in 1991–93 to 45% in 2000. The 2001 survey suggested that physical habitat below C.J. Strike Dam may not support sturgeon reproduction even during high-flow years. This latest information suggests that the sturgeon population below C.J. Strike Dam is likely supported by recruitment from the more abundant sturgeon population that occurs in the upstream reach.

The Snake River downstream of C.J. Strike Dam consists mostly of low-gradient and shallow run habitat intermixed with a few island complexes. There are essentially no significant rapids or narrow channels to create the turbulent and high-velocity conditions that are commonly associated with known sturgeon spawning and incubation areas in the Bliss–C.J. Strike, Swan Falls–Brownlee, and Hells Canyon–Lower Granite reaches of the Snake River (Lepla and Chandler 2001). These conditions, to some extent, are found in the spillway and tailrace of C.J. Strike Dam but in a very limited area.

The distribution and movement patterns of reproductive telemetered sturgeon indicated that the tailrace area was the only location used by these spawning sturgeon (Lepla and Chandler 1997).

36 Idaho Power Company Snake River White Sturgeon Conservation Plan

An instream flow study conducted by IPC found that spawning habitat below C.J. Strike Dam (tailrace and spillway) increased from almost no habitat at 5,000 cfs to 700,000 ft2 at 20,000 cfs. When considering only the tailrace, spawning habitat increased from almost no habitat at 5,000 cfs to 150,000 ft2 at 15,000 cfs (plant capacity). Spawning habitat then leveled off at flows between 15,000 and 20,000 cfs because of the backwater effect from spill (Figure 38) (Chandler and Lepla 1997).

A time-series analysis showed dramatic changes in spawning habitat availability from project operations during low- and normal-flow years, but showed little effect on spawning habitat during high-flow years because river flows exceeded plant capacity. In the low and normal water years, project operations resulted in a reduction of 80 and 90%, respectively, of the white sturgeon spawning habitat that would be present under ROR operations (Figure 39 to Figure 41). Habitat availability for all other modeled life stages (YOY, juvenile, and adult) showed minimal change from project operations. The time-series analysis indicated that habitat under project operations would generally be greater than 80% of the habitat produced under ROR operations (Figure 42 to Figure 50) (Lepla and Chandler 1997).

Results of the instream flow study indicated that project operations affect spawning habitat primarily during low- and normal-flow years; however, the physical habitat does not appear to support sturgeon reproduction even during high-flow years. Despite the occurrence of five consecutive high-flow years from 1982 to 1986, and four consecutive high-flow years from 1996 to 1999, stock structure has not changed appreciably over the past decade according to population assessments in 1989 (IDFG 1992), 1994−1996 (Lepla and Chandler 1997), and 2001 (IPC unpublished data) (Figure 37 and Figure 51). Time-series plots of sturgeon spawning habitat from 1996 to 1999 also showed that project operations at C.J. Strike Dam had little effect on the amount of sturgeon habitat during the spawning season in these years (Figure 52). These results suggest that adequate spawning conditions are generally unavailable to sturgeon below C.J. Strike Dam, and neither improved water years nor changes in project operations are expected to provide significant increases to recruitment. The overall low-gradient nature of this reach and lack of turbulent runs suggest that, historically, white sturgeon probably spawned in upstream areas of the Snake River.

4.6. Swan Falls–Brownlee Reach

4.6.1. Project and Reach Description

The Swan Falls Power Plant (RM 458) was the first power plant built on the Snake River. The original plant was built in 1901 by the Trade Dollar Mining Company to supply electricity to the mining town of Silver City, Idaho. IPC acquired the plant in 1916 when the company was formed. The old power plant had ten generators with a total generating capacity of 10.4 MW. Between 1985 and 1987, IPC rebuilt the spillway, which had deteriorated, and a new powerhouse with two horizontal Kaplan-type turbines was completed in 1994. The new turbines increased the project’s nameplate generating capacity to 25 MW. When the new license was issued and the new powerhouse constructed, a ramping rate of 1 ft per hour with a maximum of 3 ft per 24 hours was required. Minimum stream flows have been set at 5,000 cfs from April 1

37 Snake River White Sturgeon Conservation Plan Idaho Power Company through September 30 and 4,000 cfs from October 1 through March 31. State regulations also require 5,600 cfs of minimum daily average flow from November 1 through March 31. In general, Swan Falls Reservoir serves as a re-regulation pool for C.J. Strike Dam operations. Flow changes at C.J. Strike Dam generally take seven to eight hours before influencing Swan Falls Dam operations. Typically, Swan Falls Reservoir is full during early morning and late evening. Pool elevations are kept lowest between 2 to 3 PM and 2 to 3 AM to prepare to regulate the higher peak flows from C.J. Strike Dam. C.J. Strike Dam operations are occasionally modified to meet minimum flow and ramping-rate requirements at Swan Falls Dam.

The Snake River below Swan Falls Dam flows nearly 118 miles before entering the upstream end of Brownlee Reservoir near RM 340 (Figure 53). The river section between Swan Falls Dam and the top of Brownlee Reservoir displays two distinctly different characters. The top 13.7 miles of the reach are relatively high gradient and confined within a steep-walled canyon lined with large boulders and cobble banks. There are numerous turbulent runs and rapids mixed with intermittent deep pools within this section. The canyon corridor ends as the river approaches Walters Ferry (RM 444) and becomes relatively low gradient downstream to Brownlee Reservoir. This stretch extends for 104 river miles and displays a more homogenous character of shallow, low-velocity run habitat with abundant braided channels and island complexes. The river through this section flows over a more benign gravel and sand substrate and is commonly adjacent to agricultural land with lower flood-prone banks.

Brownlee Reservoir is the longest reservoir in the Snake River, extending about 55 miles at full pool. The reservoir has the total storage capacity of approximately 1.4 million acre-feet (MAF) of water and a surface area of 14,600 acres. The average depth is 32 m with a maximum depth of 92 m and median retention time of 45 days. Brownlee Reservoir is managed to serve many public purposes, including power generation and flood control, and provide recreational opportunities to the region. During winter, IPC often draws the reservoir down as much as 30 m to meet the flood-control requirements established by the U.S. Army Corps of Engineers (COE). Warming summer temperatures, combined with high nutrient loading, commonly aid in driving Brownlee Reservoir to stratify. During this stratification, the reservoir can develop an extensive hypolimnetic layer for more than half of its length. Maximum water temperatures in the Snake River upstream of Brownlee Reservoir near Weiser, Idaho, can reach 27 °C during late summer months. Summer water temperatures near the surface of Brownlee Reservoir (< 1 m) during July and August can range from 24 to 31 °C (Lepla and Chandler 2001).

Several large tributaries enter the Swan Falls–Brownlee reach, including the Owyhee, Boise, Malheur, Payette, Weiser, Burnt, and Powder rivers. Most of the tributaries have been altered to some degree and are regulated by reservoirs for flood control, irrigation, power generation, and recreation. These uses allow for highly variable annual flows (IDEQ and ODEQ 2001).

4.6.2. Population Status

White sturgeon numbers in the Swan Falls–Brownlee reach are likely a remnant of what once existed there. IPC expended 16,752 setline, 268 gill net, and 18 angling hours of effort to capture 45 white sturgeon (including 3 recaptures) in the Swan Falls–Brownlee reach during 1996 and 1997 (Table 6) (Lepla et al. 2001). Most sturgeon (n = 34) were sampled within 8 miles of Swan Falls Dam, whereas 11 sturgeon were captured near the upper end of Brownlee Reservoir

38 Idaho Power Company Snake River White Sturgeon Conservation Plan between RM 326.6 and 331.6. Overall, catch rates for sturgeon were poor regardless of the fishing gear used. The highest catch rates (0.065 fish/hr) for sturgeon sampled with setlines was near Swan Falls Dam (Figure 10), whereas gill nets captured sturgeon at only three locations in the reach (Figure 11). The abundance of sturgeon greater than 70 cm TL between Swan Falls Dam and Walters Ferry was estimated at 155 individuals (95% CI 70–621) or 7 fish/km (Table 7). Abundance of sturgeon in Brownlee Reservoir was not estimated because of the low number of fish captured during random sampling.

Sturgeon metrics in this segment are characteristic of those populations showing poor recruitment, with setline effort yielding 4% of the fish measuring less than 92 cm TL, 26% measuring between 92 and 183 cm TL, and 70% measuring greater than 183 cm TL (Figure 12e). Both gear showed similar distributions comprising primarily mid-sized and large fish with few small sturgeon (< 92 cm) represented (Figure 12e and Figure 13e). Comparisons of length– weight and growth (VBG) relationships also showed that sturgeon in this reach of the Snake River generally weighed less relative to their length and were slower growing as sturgeon approached larger sizes (Figure 14 and Figure 16). The condition factor for the majority of white sturgeon in the Swan Falls–Brownlee reach was also below average (86%) but still similar to condition factors observed for sturgeon in other riverine segments of the Snake River. Of particular interest was that the mean relative weight of sturgeon captured in Brownlee Reservoir (82%) was lower than mean relative weights of sturgeon estimated from riverine sections (Table 8). Typically, the trends in relative weight show that sturgeon residing in Snake River reservoirs have higher condition factors than those captured in riverine sections. The low mean relative weight of Brownlee Reservoir sturgeon is thought to be due in part to seasonally poor environmental conditions in Brownlee Reservoir, particularly low DO levels (Klyashtorin 1974).

Comparing the current status of sturgeon with results of earlier IDFG studies showed that sturgeon abundance in the Swan Falls–Brownlee reach has changed little over the past 30 years. Several surveys have reported low captures of sturgeon (1 [Cochnauer 1983, Kruse-Malle 1993]; 25 [Reid et al. 1973]; 42 [Reid and Mabbot 1987]). Reid and Mabbot (1987) estimated the population of sturgeon greater than 100 cm TL between Swan Falls Dam and Walters Ferry at 137 to 173, a range that is similar to the current estimate of 155 individuals. Cochnauer (1983) concluded that this population was small and had been since the early 1970s. Will Reid (IDFG, personal communication to Cochnauer 1983) hypothesized that increased fishing in response to stocking of channel catfish may have contributed to illegal harvest and mortality of sturgeon in this reach.

Size composition has also remained similar to results of previous studies (Reid et al. 1973, Reid and Mabbot 1987), with sturgeon greater than 92 cm TL dominating both current and past length frequency histograms. From 1986 to 1987, the size composition of sturgeon sampled in the Swan Falls–Brownlee reach broke out to about 3% less than 92 cm, 23% between 92 and 183 cm, and 74% greater than 183 cm, findings that closely resembled the 1996−1997 length frequency data (Figure 54). In addition, results from a 1995 IDFG mail survey for sturgeon anglers also showed a similar trend, with only 7% of the sturgeon measuring less than 92 cm (IDFG 1996). Some recruitment to the population stills occurs based on the continuing presence of a few small sturgeon and documented spawning in 1997 (Lepla and Chandler 2001). However, the number of available female spawners in the population is low (n = 7, 95% CI

39 Snake River White Sturgeon Conservation Plan Idaho Power Company

3−29) and near-future recruitment will probably also remain low, perhaps below the levels necessary to sustain this population.

Although the absence of small fish may partly result from the low number of adult fish in the reach, poor water quality also appears to contribute to low recruitment. Despite its length and habitat diversity, the Swan Falls–Brownlee reach remains one of the most degraded reaches of the Snake River. An examination of Idaho and Oregon’s 303 (d) lists shows the magnitude of substandard water quality. In particular, the water quality of the Snake River in this reach is degraded relative to temperature, organic matter, and nutrients (Table 3 and Table 4). Water temperatures can exceed 25 °C in summer, and algae and organic matter are sometimes ten times greater than levels that initiate concern. Phosphorus levels are typically double the target concentration identified by the draft Snake River–Hells Canyon Total Maximum Daily Load (TMDL) (IDEQ and ODEQ 2001, Myers et al. 2001). As a result, Brownlee Reservoir experiences severe water quality degradation, particularly in low and moderate water years, because of the extremely enriched, hypertrophic waters flowing into Brownlee Reservoir. In recent years, poor water quality in this reach has manifested itself in algae blooms and fish kills.

Degraded conditions are especially evident in the transition zone and hypolimnion of Brownlee Reservoir. During the moderate- to low-flow years, extensive and severe hypoxia has developed within these areas of the reservoir (Figure 55). During low-flow years, low DO levels lethal to white sturgeon can comprise up to 80% of the bottom 2-m layer in the transition zone of Brownlee Reservoir (Lepla et al. 2001). In worst-case scenarios, the transition area at the upstream end of the pool can become anoxic throughout the water column, an event that occurred during July 1990. At that time, Brownlee Reservoir experienced a fish kill: as many as 28 adult sturgeon were found dead, presumably because of anoxic conditions (DO < 1 mg/l) trapping sturgeon in the upper end of the reservoir (IDFG 1990).

Modeling investigations by Jager et al. (2001b) determined that, in Snake River segments with poor summer water quality, this factor dominated all others. The PVA model identified poor summer water quality to be the important issue between Swan Falls and Hells Canyon dams. Further, the model predicted that the removal of other limiting factors in the reach would not be sufficient to reestablish recruitment in these populations unless water quality also improved (Jager et al. 2001b). The effects of degraded water quality in riverine habitats on the development of early life stages of white sturgeon should be further investigated to determine whether contaminants and water temperature contribute to poor recruitment. For instance, studies conducted in the Kootenai River have shown very high mortality on incubating white sturgeon eggs when they are coated with suspended solids and then incubated in unfiltered water from the Kootenai River. Organic matter and contaminants from suspended solids and river water were likely the primary sources of bacteria and fungi that contributed to the low survival of these embryos (Kruse 2000). The Swan Falls–Brownlee reach receives very high organic loading from the surrounding watersheds (Harrison et al. 1999, Myers et al. 2001). This additional burden may affect the survival of incubating sturgeon eggs. Additionally, the bioaccumulation of contaminants in adult sturgeon may be passed through the eggs or sperm and affect embryo viability, although the overall effect of these pollutants on sturgeon reproduction and survival are largely unknown.

40 Idaho Power Company Snake River White Sturgeon Conservation Plan

4.7. Brownlee–Oxbow Reach

4.7.1. Project and Reach Description

Brownlee Dam (RM 284.6) was completed in 1959 for energy production, flood control, and recreational opportunities. This rock-filled dam is about 1,380 ft long and 395 ft high. The powerhouse has a total nameplate generating capacity of 585 MW. Flows in excess of 35,000 cfs are passed at the spillway facilities, which are located on the west bank of the river.

This reach of the Snake River is relatively short, extending only 12 river miles to Oxbow Dam at RM 272.5 (Figure 56). No free-flowing habitat exists in this segment because Oxbow Dam backs water to the tailwater of Brownlee Dam. Oxbow Reservoir has a maximum depth approaching 30 m, with a total surface area of 1,150 acres at full pool and a median retention time of 1.9 days. Daily operations regularly call for surface elevations to fluctuate 1.2 m. The reservoir has also been designated as water quality limited, due primarily to processes occurring in Brownlee Reservoir (Myers and Pierce 1999). The Wildhorse River is the only significant tributary entering the segment.

4.7.2. Population Status

IPC expended 2,913 setline and 32 gill net hours of effort in Oxbow Reservoir during 1998 (Table 6). Although no sturgeon were captured in this reach, anecdotal evidence suggests that some sturgeon remain although in low numbers. Between 1994 and 2001, six dead sturgeon were observed immediately below Brownlee Dam in the tailrace. Some of these sturgeon carcasses showed signs of external injury, presumably from a turbine blade strike or contact with a concrete wall as they left the draft tube following a unit startup (Lepla et al. 2001). A small number of hatchery sturgeon (n = 113) were also stocked in this reach in 1991 and 1994 (Table 10), although none were sampled during the 1998 survey. The status of white sturgeon in Oxbow and Hells Canyon reservoirs appears unchanged since the earlier IDFG surveys. Welsh and Reid (1971) concluded that, although anglers had captured sturgeon in the tailrace of Brownlee Dam, the species is probably not abundant in Oxbow Reservoir.

The Snake River between Brownlee and Oxbow dams is composed entirely of reservoir habitat. Velocities suitable for spawning may be available in the tailrace of Brownlee Dam; however, this reach does not contain the free-flowing habitats and conditions that are often associated with sturgeon spawning observed in other reaches of the Snake River. In addition to limited spawning habitat in the Brownlee Dam tailrace, the reservoir may also affect recruitment success by increasing predation on egg and larvae.

In addition to the lack of spawning habitat, shorter reaches in the Snake River also appear more susceptible to downstream export of white sturgeon than longer reaches: over time, the population erodes as fish move to downstream areas. A common observation in short reaches of both the Mid-Snake and Hells Canyon complexes has been little or no detectable presence of sturgeon recruitment. PVA simulations also suggested that larval export is limiting recruitment in shorter segments of the Snake River (Jager et al. 2001b). The tendency for early life stages to disperse over wide areas (see section 2 about the biology of white sturgeon) lends support to the

41 Snake River White Sturgeon Conservation Plan Idaho Power Company assumption that shorter river segments experience high levels of downstream export of white sturgeon.

4.8. Oxbow–Hells Canyon Reach

4.8.1. Project and Reach Description

Oxbow Dam (RM 272.5), completed in 1961, takes its name from a 3-mile bend in the Snake River where the river carved a course around a mass of erosion-resistant rock (Figure 56). Oxbow Dam was the second dam constructed in the HCC and has a nameplate capacity of 190 MW. The hydraulic capacity of the powerhouse is 28,000 cfs. Hells Canyon Dam (RM 247.6) forms the lower bound of this 22-mile segment and impounds water the entire length of the reach. Hells Canyon Reservoir has a maximum depth of 60 m and is characterized by steep rocky shorelines with basalt outcrops and talus hillslopes (Lepla and Chandler 2001). This reservoir has a surface area of 2,412 acres at full pool, a total storage capacity of 167,720 acre-feet, and a median retention time of 5.2 days. During July and August of low-flow years, up to 52% of the reservoir’s bottom 2 m is characterized by poor water quality conditions such as low DO levels (Lepla and Chandler 2001). Major tributaries within this segment include Pine Creek and Indian Creek, which together contribute an average annual flow of 400 cfs.

4.8.2. Population Status

In Hells Canyon Reservoir, IPC captured four sturgeon with 2,690 setline and 39 gill net hours of effort (Table 6) (Lepla et al. 2001). Three wild adult sturgeon and one juvenile hatchery sturgeon were caught with setline gear near the upper end of Hells Canyon Reservoir between RM 263.4 and 269.9 (Figure 10). The wild sturgeon ranged in length from 139 to 250 cm TL, while the hatchery fish measured 63 cm TL (Figure 12f). The sturgeon displayed relatively good growth rates and fish condition when considering mean length-at-age and relative weight (93%, Table 8). The status of white sturgeon in Hells Canyon Reservoir appears unchanged since the earlier surveys. Welsh and Reid (1971) concluded that the species is probably not abundant in either Oxbow Reservoir or Hells Canyon Reservoir. The Oregon Department of Fish and Wildlife (ODFW) also expended some sampling effort in this reach during 1992 and reported similar results. A total of six wild and one hatchery sturgeon were captured and ranged in length from 51 to 280 cm TL. The size composition of sturgeon remained similar between 1992 and 1998 surveys, with large sturgeon dominating the catch and no detectable presence of small wild sturgeon (Figure 57). The condition factor of sturgeon (93%) in 1992 was also similar to fish condition observed during the 1998 survey (Table 8).

Limited numbers of hatchery-reared juvenile sturgeon have also been released into Hells Canyon Reservoir from two stocking events (Table 10). In 1991, IDFG first stocked 100 hatchery juvenile sturgeon that were progeny from broodstock collected in the Bliss–C.J. Strike reach and raised at the College of Southern Idaho aquaculture facility. The single hatchery sturgeon captured in 1998 was from the 1991 stocking effort. The Nez Perce Tribe conducted the second stocking event in 2000. A total of 50 hatchery juvenile sturgeon were released as part of preliminary efforts to evaluate the feasibility of a put-and-take fishery in Hells Canyon

42 Idaho Power Company Snake River White Sturgeon Conservation Plan

Reservoir. These fish were also the progeny of broodstock collected in the Bliss–C.J. Strike reach and reared at a private commercial facility in Hagerman, Idaho.

The low number of sturgeon sampled during 1992 (ODFW unpublished data) and 1998 (Lepla et al. 2001) indicates that few sturgeon remain between Oxbow and Hells Canyon dams. Given the few adult sturgeon remaining and the variable reproductive readiness that occurs between the sexes, there are few opportunities for reproduction in this reach. In addition, the Snake River between Oxbow and Hells Canyon dams is composed almost entirely of reservoir habitat except for a limited amount of free-flowing habitat near the upper end of the Oxbow Bypass and in the immediate vicinity of the powerhouse tailrace. An instream flow assessment of the Oxbow Bypass and tailrace found that habitat for the incubation life stage is potentially limiting within Hells Canyon Reservoir (Myers and Chandler 2001). Study results showed that, at 20 kcfs, suitable incubation and spawning habitat in the Oxbow Bypass only ranged from 6% to 25%, respectively, of the total area (Figure 58 and Figure 59). The tailrace of Oxbow Dam provided greater amounts of habitat at comparable flows, although it was still low relative to total area (Figure 60 and Figure 61). Larval and YOY habitat conditions were better than those for incubation, although such conditions were still rare. No significant relationship existed between flow and habitat for the older life stages of white sturgeon (Myers and Chandler 2001).

The reservoir may also affect recruitment success by increasing predation on white sturgeon eggs and larvae. Shorter reaches in the Snake River also appear more susceptible to downstream export of white sturgeon than longer reaches: over time, the population erodes as fish move to downstream areas. Part of white sturgeon ecology includes dispersal of the early life stages from spawning sites to areas suitable for feeding and rearing. This tendency for early life stages to disperse over wide areas lends support to the assumption that shorter river segments experience high levels of downstream export of white sturgeon.

4.9. Hells Canyon–Lower Granite Reach

4.9.1. Project and Reach Description

The third dam in the HCC is Hells Canyon Dam (RM 247.6), which was completed in 1967. It is a concrete dam about 330 ft high and 1,000 ft long. This dam has three generating units fitted with Francis runners and a nameplate generating capacity of 391 MW. River flows in excess of 30,500 cfs are passed at the spillway, which is located near the Idaho bank.

The Hells Canyon section of the Snake River flows through the deepest canyon in North America, creating a series of turbulent rapids and runs intermixed with many deep pools. High mountain peaks, basalt canyon rimrock, and steep hillslopes characterize the Hells Canyon corridor. The Snake River in this reach flows freely for 107 miles before entering Lower Granite Reservoir (Figure 62). Lower Granite Dam, located at RM 107.5, was completed in 1975 and impounds water for about 32 miles. Several large tributaries—including the Imnaha, Salmon, and Grande Ronde rivers—join the Snake River above Lower Granite Reservoir.

43 Snake River White Sturgeon Conservation Plan Idaho Power Company

4.9.2. Population Status

The white sturgeon population in the Hells Canyon–Lower Granite reach is currently the largest viable population in the Snake River. Three studies to describe the white sturgeon population in the Hells Canyon–Lower Granite reach were conducted in 1972 (Coon et al. 1977) 1984 and 1985 (Lukens 1985), and 1997 to 2000 (Everett and Tuell 2001, Lepla et al. 2001). During the most recent survey (1997–2000), IPC captured 923 white sturgeon (which included 270 recaptures) between Granite Rapids (RM 238) and the mouth of the Salmon River (RM 188) with 27,658 setline and 681 angling hours of effort (Table 6) (Lepla et al. 2001). As part of cooperative sampling efforts during the 1997–2000 period, the Nez Perce Tribe captured a total of 876 sturgeon (with 106 recaptures) from the Salmon River confluence downstream to Lower Granite Dam (Everett and Tuell 20015). The abundance of white sturgeon in the Hells Canyon– Lower Granite reach was estimated at 3,625 individuals greater than 70 cm TL or 17 fish/km (Table 7), based on combined data from concurrent IPC (Hells Canyon Dam to the Salmon River) and Nez Perce Tribe (Salmon River to Lower Granite Dam) efforts. While previous surveys of sturgeon abundance provided higher estimates in the segment (8,200−12,250, Coon et al. 1977; 3,955, Lukens 1985), these previous surveys used dissimilar gear and sampling protocols and cannot be accurately compared (Cochnauer 2002).

During the 1997–2000 survey, IPC and the Nez Perce Tribe captured white sturgeon ranging in length from 52 to 291 cm TL. A length frequency histogram showed that 53% of the sturgeon captured with setlines were less than 92 cm TL, 29% were between 92 and 183 cm TL, and 18% were greater than 183 cm TL (Figure 12g). This current stock structure closely resembles IDFG’s desired management goal of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL. Mean relative weight for sturgeon in Lower Granite Reservoir (95%) was higher than for those fish sampled in riverine habitat (87%). The mean relative weight for all sturgeon sampled in the Hells Canyon–Lower Granite reach was 88% of the standard weight (Table 8). Comparison of relative weights were not significantly different (P = 0.08) from relative weights observed by Coon et al. (90%, 1977) or by Lukens (89%, 1985), suggesting that overall fish condition in this segment has remain relatively unchanged since the early 1970s. Length–weight and growth (VBG) relationships showed that growth rates for larger sturgeon below Hells Canyon Dam were lower than growth rates for sturgeon in the upper reaches of the Snake River (Figure 14 and Figure 16).

Survival and reproductive rates for sturgeon downstream of Hells Canyon Dam were comparable to other white sturgeon subpopulations in the Snake River. Annual mortality (A) and survival (S) rates for sturgeon caught between Hells Canyon and the Salmon River was 0.13 (A) and 0.87 (S) (Table 9). The reproductive potential (11%) of female white sturgeon below Hells Canyon Dam within a given year was comparable with the reproductive potential (13%) of females in the sturgeon population below Bliss Dam, the second largest sturgeon population in the Snake River above the HCC.

5 At the time of IPC’s analysis, Everett and Tuell (2001) included the most current information on white sturgeon from the Nez Perce Tribe study. These data were made available to IPC through a data-sharing agreement with the tribe. This information has since been updated and is found in Everett and Tuell (2003).

44 Idaho Power Company Snake River White Sturgeon Conservation Plan

Most interesting is the positive response in the size structure below Hells Canyon Dam following changes in sturgeon fishing regulations in 1972. Fishing regulations regarding sturgeon harvest became increasingly restrictive until 1972, when catch-and-release regulations were enacted in Idaho for the sturgeon populations in the Snake and Salmon rivers. Based on recent survey data, the sturgeon population below Hells Canyon Dam has responded well from impacts of prior catch-and-keep sport regulations (Cochnauer et al. 1985, Cochnauer 2002). While juvenile fish less than 92 cm TL continue to dominate the population, abundance of fish greater than 92 cm TL has steadily grown since the 1970s. The percentage of sturgeon 92 to 183 cm TL, the legal harvestable size prior to 1972, has increased from 4% in 1972–1975 (Coon et al. 1977) to 18% in 1982–1984 (Lukens 1985) to 29% in 1997–2000 (Lepla et al. 2001). Similarly, sturgeon greater than 183 cm TL have also responded positively to the restrictions by increasing in abundance from 2% in 1982–1984 to 18% in 1997–2000 (Figure 63).

The Hells Canyon–Lower Granite reach is the most natural river reach, except for the Salmon River, among all of the impounded Snake and Columbia river reaches inhabited by sturgeon (Cochnauer 2002). Suitable habitats such as water velocities, substrate, water temperatures, and diversity are all still present in the free-flowing reach that extends from the headwaters of Lower Granite Reservoir upstream to Hells Canyon Dam. Although Chandler et al. (2002) reported that project operations at Hells Canyon Dam could reduce the availability of modeled habitat for early life stages of white sturgeon during low-flow years (Table 11), the size structure of the Hells Canyon population suggests continuous recruitment. Stock assessments conducted between 1972 and 2000 have indicated positive and consistent recruitment trends with juveniles dominating the population. The population currently supports both catch-and-release sport (including incidental angling mortality) and tribal harvest fisheries. Although the current density estimate (17 fish/km) is lower than the target density (32 fish/km) identified in IDFG’s white sturgeon management plan, the Hells Canyon–Lower Granite sturgeon population is genetically diverse and exhibits a healthy population structure, based on the current stock structure dominated by juveniles, wide range of size classes, and stages of maturity from immature juveniles to reproductive adults.

5. POPULATION VIABILITY ANALYSIS

A population viability analysis was initiated for Snake River white sturgeon in 1998 as part of the relicensing process for the HCC. PVA is an iterative process that, in part, uses models and data to compare the chances that a population will persist for some arbitrarily chosen time under alternative management practices (Boyce 1992). The PVA provides a means of integrating and applying results of field and laboratory studies on white sturgeon with other studies that define physical processes and conditions to address the question of population viability.

A PVA was used to evaluate various risks to the long-term persistence of white sturgeon populations in the Snake River between Shoshone Falls and Lower Granite Dam. The model was used to predict the likelihood of sturgeon persistence and to estimate the distribution of final population sizes at the end of 200 years. The baseline simulations predicted that three subpopulations, those (two) between Bliss and Swan Falls dams and the one below Hells Canyon Dam, would persist for 200 years. Sturgeon populations not expected to persist included those in

45 Snake River White Sturgeon Conservation Plan Idaho Power Company reaches between Swan Falls and Hells Canyon dams. Simulation results also indicated that the numbers of sturgeon in reaches between Shoshone Falls and Lower Salmon Falls Dam would be very low (Jager et al. 2001a).

Although factors predicted by the model to influence sturgeon recruitment differed among river segments, results clearly showed a distinction between river segments limited by episodic poor water quality and those with adequate water quality. In river segments between Swan Falls and Hells Canyon dams, poor summer water quality dominated over all other sources of mortality. This factor even had indirect consequences downstream of Hells Canyon Dam because this reach received fewer simulated downstream migrants when water quality was poor upstream. The model predicted that removing other mechanistic mortality factors would be insufficient for reestablishing recruitment in these populations unless water quality also improved. Brownlee Reservoir experiences severe water quality degradation in low- and moderate-flow years because of nutrient influxes from agricultural activity and municipal wastes from surrounding watersheds. Only in high-flow years are summer flows high enough to prevent large populations of algae from developing and producing anoxic conditions in the reservoir.

Second, among river segments with better water quality, short river segments were regulated by different factors than longer segments were. Four short river segments (i.e., below Upper Salmon Falls, Lower Salmon Falls, Brownlee, and Oxbow dams, which are 11, 21, 19, and 42 km in length, respectively) consist primarily of impounded reservoir habitat. Field studies indicate that these reservoirs support very small white sturgeon populations and produce no detectable numbers of young fish. Because of the closeness of adjacent dams, these segments have little or no free-flowing habitat. The two segments between Upper Salmon Falls and Bliss dams do not have severe water quality problems. Rather, larval export was predicted to be a limiting factor in these reservoirs. In short impounded segments of the Rio Grande and Pecos rivers of New Mexico (Plantania and Altenbach 1998), export losses have been implicated as a cause for the extirpation of broadcast-spawning cyprinids with semibuoyant eggs. In the case of white sturgeon, eggs are adhesive, and dispersal occurs later, during the larval and early juvenile life stages. Jager et al. (2002) noted that spawner limitations might also be an important cause of lost recruitment in short river segments. Because fewer adults are available to reproduce in these short segments, simulated opportunities for reproduction and recruitment are less frequent. As a result, small populations are typically more vulnerable to extinction than larger populations. Our simulation experiments were not designed to quantify spawner limitation in these reservoirs, but such effects of fragmentation are discussed more generally in Jager et al. (2001b).

The four longer river segments with adequate water quality are those below Shoshone Falls, Bliss, C.J. Strike, and Hells Canyon dams. Identifying a single limiting factor was not as useful for these longer segments because recruitment showed a relatively weak response to several factors. Angling, larval export (or rather larval import from upstream), flow during incubation, turbine strike, and poor water quality had impacts in one or more of these longer river segments. Two mortality factors that increase in proportion to population size tended to be important in the longer segments with larger populations, between Bliss and C.J. Strike dams and below Hells Canyon Dam. For example, angling reduced simulated recruitment between Bliss and Brownlee dams and below Hells Canyon Dam because angling pressure increased in these segments having higher sturgeon densities. Likewise, the importance of entrainment and turbine

46 Idaho Power Company Snake River White Sturgeon Conservation Plan strike increases with the size of the upstream population. For a complete description of the model and PVA results, see Jager et al. (2001a) in Appendix 1 of this report.

6. GOAL AND TARGETS

6.1. Goal

The following is the long-term goal for Snake River white sturgeon, as developed by the WSTAC and defined in the WSCP:

To mitigate for IPC project-related impacts in order to provide for healthy populations of white sturgeon in each reach of the Snake River between the mouth of the Salmon River and Shoshone Falls, not including the reach between Upper Salmon Falls and Lower Salmon Falls dams. A healthy population, as defined by the WSCP, is a reproducing population capable of sustaining itself at or near carrying capacity of available habitat without artificial propagation, resilient in the face of natural variations in habitat conditions, and capable of supporting a tribal and non-tribal harvestable fishery.

The ability to fully achieve the goal of healthy white sturgeon populations in each reach of the Snake River within the anticipated term (approximately 30 years) of new licenses for several IPC projects appears unlikely and may even be impossible in some reaches given the extent of the system alterations and habitat degradation of the Snake River ecosystem. However, the long life span of white sturgeon requires a long-term perspective in planning and commitment to sturgeon management. Therefore, the goal, as stated in the WSCP, must be considered “long term” and beyond the anticipated term of the new project licenses.

Short-term objectives will be necessary to guide mitigation actions within the time frame of new hydroelectric project licenses. In addition, a guiding principle in the development of this WSCP is that actions to restore sturgeon populations in depressed reaches must not place existing viable sturgeon populations (Bliss–C.J. Strike and Hells Canyon–Lower Granite populations) at risk. Sturgeon populations below Bliss and Hells Canyon dams currently provide self-sustaining natural recruitment and are considered genetically diverse (M. Powell; University of Idaho; personal communication to the WSTAC, August 8, 2002). Because of these conditions, mitigation actions undertaken in the various reaches of the Snake River should not threaten the persistence and viability of these two remaining wild sturgeon populations. The following are the short-term objectives of the WSCP:

Objective 1 Maintain and/or enhance population viability and persistence of Snake River white sturgeon below Bliss and Hells Canyon dams, and where feasible

Objective 2 Begin to reestablish recruitment to sturgeon populations where natural recruitment is severely limited

47 Snake River White Sturgeon Conservation Plan Idaho Power Company

Reaches where natural recruitment is severely limited or no longer occurs include those below Shoshone Falls, Upper Salmon Falls, Lower Salmon Falls, C.J. Strike, Swan Falls, Brownlee, and Oxbow dams. Reestablishing recruitment within these reaches will depend on the degree to which limiting factors for sturgeon can be effectively addressed. For instance, PVA model simulations (see section 5) have indicated that sturgeon populations in short reaches (below Upper Salmon Falls, Lower Salmon Falls, Brownlee, and Oxbow dams) of the Snake River would not be self-sustaining due to larval export. Several of these short reaches (below Upper Salmon Falls, Brownlee, and Oxbow dams) also consist primarily of reservoir environments and lack quality riverine habitats to support natural recruitment. The ability to improve upon existing impairments in these reaches may be infeasible in the short term (i.e., the life of a project license). It is likely that population-restoration efforts relying on natural production within these reaches will be severely hampered. In such cases, actions to supplement natural recruitment may be used and/or tested in reaches that do not place wild sturgeon populations at risk. Given the uncertainty in outcomes at this time, continuing an adaptive approach to restoration efforts will be necessary as we learn the results of implementing proposed measures.

6.2. Targets

Targets listed below represent population-response variables by which the progress and effectiveness of proposed mitigation actions can be measured. These targets represent the desired benchmarks for achieving healthy populations of Snake River white sturgeon. Given the uncertainty in fully achieving the goal of naturally producing and self-sustaining populations in all defined reaches of the Snake River, we may need to refine reach-specific targets and/or develop additional targets to gauge the progress and effectiveness of alternative measures.

1. Population density of 32 fish/km of usable habitat in Snake River reaches from Shoshone Falls to Lower Granite dams.

Thirty-two fish/km of usable habitat represents the desired density for Snake River white sturgeon populations, as defined in the State of Idaho’s draft White Sturgeon Management Plan (IDFG 2002). This population density estimate was determined from the model simulation of the Bliss–C.J. Strike population demographics and the estimate of usable stream and reservoir habitat within this reach (T. Cochnauer; IDFG; personal communication to the WSTAC, May 8, 2001). The target density currently assumes that stream and reservoir habitats (based on maximum channel depth) in other reaches can support densities of sturgeon similar to those observed in the Bliss–C.J. Strike reach. As future population monitoring is conducted, target densities for specific reaches may be refined, pending data about growth rates and condition factor and results of additional modeling of reach properties that influence the success of white sturgeon.

2. Naturally produced recruitment to support a stock structure consisting of about 60% of the individuals between 60 and 90 cm TL, 30% between 90 and 180 cm TL, and 10% greater than 180 cm TL.

A stock structure dominated by juveniles indicates that successful reproduction and recruitment is occurring and provides for replacement of adults in the population.

48 Idaho Power Company Snake River White Sturgeon Conservation Plan

3. Stable or increasing trends in juvenile and adult numbers.

Stable or increasing trends require recruitment rates that equal or exceed natural and human- caused mortality rates. Stable population sizes and ages reflect the longevity and normal population structure of sturgeon; this stability also provides the population resilience needed to sustain these fish over the long term.

4. Maintenance of genetic diversity (including rare alleles) similar to current levels observed for Snake River white sturgeon.

Stable genetic diversity similar to existing levels ensures that sufficient variability is preserved to allow sturgeon to use the available array of environments, protect against short- term spatial and temporal changes in the environment, and provide the raw material for surviving long-term environmental changes (McElhany et al. 2000).

7. RECOMMENDED MEASURES BY WSTAC

The WSTAC developed a list of conceptual measures for the various Snake River reaches (Appendix 2). These measures were to be considered for inclusion in the WSCP. The WSTAC then recommended the following measures from that list of conceptual measures. These recommendations are organized by reach for Snake River white sturgeon populations.

DISCLAIMER

Recommended measures do not indicate consensus, nor do they necessarily represent the views or the official positions of any individuals or agencies participating in the WSTAC.

7.1. Shoshone Falls–Upper Salmon Falls Reach

• Monitor success of white sturgeon spawning and early life history survival.

• Determine and obtain minimum flows needed for white sturgeon spawning, incubation, and early rearing life stages.

• Translocate reproductive-sized adults to increase number of spawners in the population and improve white sturgeon productivity.

• Develop experimental conservation aquaculture plan.6

• Conduct periodic population assessments (time frame to be determined [TBD]).

6 The intent of the WSTAC is not to enter into a conservation aquaculture program without first fully exploring the restoration of quality habitat and/or genetic implications of hatchery supplementation.

49 Snake River White Sturgeon Conservation Plan Idaho Power Company

• Evaluate the historical white sturgeon hatchery plants (genetic implications, competition with wild fish, movement, etc.).

• Develop a genetics plan that addresses the current status and implications of translocations and potential hatchery introductions.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.2. Upper Salmon Falls–Lower Salmon Falls Reach

• Conduct periodic population assessments (time frame TBD).

• Determine feasibility of passage in the North Channel below Upper Salmon Falls Dam.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.3. Lower Salmon Falls–Bliss Reach

• Evaluate status of hatchery sturgeon stocked during 1989–1994.

• Evaluate the historical white sturgeon hatchery plants (genetic implications, competition with wild fish, movement, etc.).

• Conduct periodic population assessments (time frame TBD).

• Develop experimental conservation aquaculture plan.7

• Develop a genetics plan that addresses the current status and implications of potential hatchery introductions.

• Implement seasonal run-of-river project operations at Lower Salmon Falls Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TBD).

• Monitor water quality response from measures implemented in § 401 water quality certification for the Mid-Snake projects.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7 The intent of the WSTAC is not to enter into a conservation aquaculture program without first fully exploring the restoration of quality habitat and/or genetic implications of hatchery supplementation.

50 Idaho Power Company Snake River White Sturgeon Conservation Plan

7.4. Bliss–C.J. Strike Reach

• Conduct periodic population assessments (time frame TBD).

• Develop a genetics plan that addresses the current status and implications of translocations.

• Monitor for changes in genotype frequency.

• Implement seasonal run-of-river project operations at Bliss Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TBD).

• Improve water quality in C.J. Strike Reservoir: a) Develop specific measures to improve water quality conditions through consultation with IDEQ within the framework of the C.J. Strike–Succor Creek TMDL implementation and the § 401 water quality certification process for the C.J. Strike Project, and b) Study discharge options at C.J. Strike Dam to improve water quality conditions.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.5. C.J. Strike–Swan Falls Reach

• Provide habitat conditions suitable for white sturgeon spawning: a) Transplant reproductive- sized adults to suitable spawning habitat in the Bliss–C.J. Strike reach, b) Determine feasibility of a trapping facility to collect spawners (or all ages) below C.J. Strike Dam, and c) Determine feasibility of developing spawning and incubation habitats below C.J. Strike Dam.

• Determine feasibility of reduced trash bar spacing to minimize turbine entrainment and impingement of white sturgeon.

• Conduct periodic population assessments (time frame TBD).

• Develop a genetics plan that addresses the current status and implications of translocations.

• Monitor for changes in genotype frequency.

• Evaluate effect of catch-and-release angling below C.J. Strike Dam in cooperation with IDFG.

• Implement seasonal run-of-river project operations at C.J. Strike Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TBD).

• Improve water quality in C.J. Strike Reservoir: a) Develop specific measures to improve water quality conditions through consultation with IDEQ within the framework of the C.J. Strike–Succor Creek TMDL implementation and the § 401 water quality certification

51 Snake River White Sturgeon Conservation Plan Idaho Power Company

process for the C.J. Strike Project, and b) Study discharge options at C.J. Strike Dam to improve water quality conditions.

• Determine feasibility of passage at C.J. Strike Dam.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.6. Swan Falls–Brownlee Reach

• Conduct an assessment of water quality-related impacts on early life stages of white sturgeon development.

• Improve water quality conditions in Brownlee Reservoir to meet Idaho and Oregon state criteria for dissolved oxygen, temperature and total dissolved gas.

• Translocate reproductive-sized adult white sturgeon to increase number of spawners and improve white sturgeon productivity.

• Monitor success of white sturgeon spawning and early life history survival.

• Develop experimental conservation aquaculture plan.8

• Conduct periodic population assessments (time frame TBD).

• Develop a genetics plan that addresses the current status and implications of translocations and potential hatchery introductions.

• Monitor for changes in genotype frequency.

• Increase flow.

• Restore/protect riparian areas to hasten water quality improvements.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.7. Brownlee–Hells Canyon Reach

• Improve water quality conditions in Oxbow and Hells Canyon reservoirs to meet Idaho and Oregon state criteria for dissolved oxygen, temperature and total dissolved gas.

8 The intent of the WSTAC is not to enter into an aquaculture program without first fully exploring restoration of quality habitats and/or genetic implications of hatchery supplementation.

52 Idaho Power Company Snake River White Sturgeon Conservation Plan

• Transplant reproductive-sized adult white sturgeon to increase number of spawners and improve white sturgeon productivity.

• Monitor success of white sturgeon spawning and early life history survival.

• Develop experimental conservation aquaculture plan in cooperation with the IDFG, Nez Perce Tribe, and ODFW. 9

• Develop a genetics plan that addresses the current status and implications of translocations and potential hatchery introductions.

• Conduct periodic population assessments (time frame TBD).

• Take no action.

• Determine the feasibility of passage at the HCC.

• Evaluate the feasibility of dam removal.

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

7.8. Hells Canyon–Lower Granite Reach

• Conduct periodic population assessments (time frame TBD).

• Develop a genetics plan that addresses the current status and implications of translocations.

• Monitor for changes in genotype frequency.

• Determine the effect of translocation on donor population.

• Improve water quality conditions below Hells Canyon Dam to meet Idaho and Oregon state criteria for dissolved oxygen, temperature and total dissolved gas.

• Implement seasonal run-of-river project operations at Hells Canyon Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TBD).

• Develop a schematic flow chart outlining PM&E measures with associated tasks, time frames, and decision points.

9 The intent of the WSTAC is not to enter into an aquaculture program without first fully exploring restoration of quality habitats and/or genetic implications of hatchery supplementation.

53 Snake River White Sturgeon Conservation Plan Idaho Power Company

7.9. Recommended Measures Not Specific to White Sturgeon

• Determine off-site mitigation for ongoing losses and impacts to white sturgeon between Brownlee and Hells Canyon dams.

8. MEASURES PROPOSED BY IPC

Measures included in this section are those that IPC proposes to implement after new project licenses are issued. Outlines of the proposed mitigation measures—including justification, objective, description, implementation schedule, and cost estimates—are presented in sections 8.1. to 8.8. and summarized in Table 12. Detailed study plans for each measure would be developed once a project license were issued and reviewed with the WSTAC before the measures were implemented. IPC recognizes that the jurisdiction, management, and protection responsibilities for Snake River white sturgeon rightfully belong to managing resource agencies and that implementation of mitigation measures would require extensive and continual involvement from resource agencies and continuation of the WSTAC. Given the uncertainty about the specific outcomes of various measures, a framework of potential pathways with decision points has been developed that allows for an adaptive roadmap in implementing and revising measures based on their success (Figure 64 and Figure 65). At decision points along the various pathways, measures would be reviewed for their effectiveness and decisions would be made on whether to continue or modify these measures or whether alternative measures were warranted. At decision points where consensus could not be achieved on a measure, the decision to implement a measure would be made by the licensee subject to approval by FERC. A summary of the proposed measures is provided below:

Reach2 Proposed Measures [Tasks Associated with Measures]1 SHF USF LSF BL CJS SF BR OX HC Translocate reproductive-sized adults below C.J. Strike Dam to spawning habitat in the Bliss– 8.5.1. C.J. Strike reach [Evaluate genetic implications of translocation on donor and recipient populations] Determine feasibility of constructing

spawning and incubation habitats *8.5.2. Determine feasibility of acoustic camera technology to identify white

sturgeon and monitor turbine *8.5.3. entrainment Determine feasibility of reducing

trash bar spacing *8.5.3. Assess water quality-related 8.6.1. impacts on early life stages IImprove DO and TDG conditions in 8.6.2. 8.7.1. 8.7.1. 8.8.1. the Hells Canyon Complex.

54 Idaho Power Company Snake River White Sturgeon Conservation Plan

Reach2 Proposed Measures [Tasks Associated with Measures]1 SHF USF LSF BL CJS SF BR OX HC Translocate reproductive-sized adults to increase spawner abundance and population

productivity [Evaluate genetic *8.6.3. implications of translocation on donor and recipient populations] Monitor spawning and early life 8.1.1. *8.6.3./ stage survival 8.6.1. Develop experimental conservation aquaculture program [Evaluate 8.1.2. 8.6.4. genetic implications of hatchery * * introductions] Conduct periodic population assessment [Evaluate historical 8.1.3. 8.2.1. 8.3.1. 8.4.1. 8.5.4. 8.6.5. 8.7.2. 8.7.2. 8.8.2. stockings of hatchery sturgeon in SHF, LSF, OX] Monitor genotypic frequencies 8.1.4. 8.2.2. 8.3.2. 8.4.2. 8.5.5. 8.6.6 8.7.3. 8.7.3. 8.8.3. Evaluate effects of angling below 8.5.6. C.J. Strike Dam Monitor response to measures implemented for § 401 water quality 8.1.5. 8.2.3. 8.3.3. 8.4.3. certification for Mid-Snake projects Improve water quality by developing specific measures through the C.J. 8.4.4. 8.5.7. Strike TMDL. Develop schematic diagram for 8.1.6. 8.2.4. 8.3.4. 8.4.5. 8.5.8. 8.6.7. 8.7.4. 8.7.4. 8.8.4. proposed mitigation measures 1 Proposed Measures: Numbers in columns indicate the section of the text where the proposed measure is discussed; * indicates measure implementation contingent on feasibility and/or evaluation of study results of previous measures. 2 Reach Definition: SHF = Shoshone Falls to Upper Salmon Falls dams, USF = Upper Salmon Falls to Lower Salmon Falls dams, LSF = Lower Salmon Falls to Bliss dams, BL = Bliss to C.J. Strike dams, CJS = C.J. Strike to Swan Falls dams, SF = Swan Falls to Brownlee dams, BR = Brownlee to Oxbow dams, OX = Oxbow to Hells Canyon dams, and HC = Hells Canyon to Lower Granite dams.

8.1. Shoshone Falls–Upper Salmon Falls Reach

8.1.1. Monitor Spawning and Early Life Stage Survival

8.1.1.1. Justification The absence of small wild fish during the 1980–1981 survey (Lukens 1981) and the capture of only two juvenile wild sturgeon (less than 80 cm) in the 2001 survey (Lepla et al. 2002) suggest that little natural recruitment has occurred to the Shoshone Falls–Upper Salmon Falls sturgeon population over the last 20 years. Lukens (1981) concluded that the lack of recruitment was probably a result of low spawner numbers coupled with low spawning frequency. Although having too few spawners in the population may have contributed to past poor recruitment trends, spawner limitations may soon be alleviated as hatchery white sturgeon approach maturity. Based on the population’s demographics in 2001, an increasing number of hatchery fish will probably approach maturity within the next five or more years (section 4.1.2.). While river flows passing over Shoshone Falls are often affected by upstream irrigation diversions, normal and/or above-

55 Snake River White Sturgeon Conservation Plan Idaho Power Company normal hydrologic years may produce conditions favorable for spawning and recruitment. White sturgeon probably produced strong year classes infrequently, even under historical circumstances (Jager et al. 2002). These fish exemplify the “periodic” life history strategy with high fecundity, late maturation, and high mortality of early life stages (Winemiller and Rose 1992). Periodic species are sustained by infrequent episodes of very successful recruitment, which occurs when the annually varying environmental conditions are favorable. Documenting spawning events would provide the first step in determining whether spawner limitations have been overcome and whether successful spawning occurs under existing hydrologic regimes. The success of spawning events and survival of early life stages would be assessed by means of juvenile capture surveys. Such surveys would determine whether sturgeon recruit to the population at levels that support population growth and maintenance.

8.1.1.2. Objective Determine whether increased spawner abundance and existing flow regimes support natural production of white sturgeon in the Shoshone Falls–Upper Salmon Falls reach.

8.1.1.3. Description IPC would use radio telemetry to monitor spawning behavior and identify key spawning locations. Reproductive adults would be captured and fitted with radio transmitters before the spawning season and then monitored throughout the spawning season. Artificial substrate mats would be deployed at likely spawning sites and where telemetered fish are staging. Biologists would use eggs collected from artificial substrate mats to estimate timing (by determining developmental stage) and macroscale habitat conditions associated with spawning events. After spawning occurred, IPC would attempt to recapture the telemetered spawners to surgically confirm whether these selected individuals had spawned.

The success of spawning events would be followed up by juvenile capture surveys, the earliest life stage that would provide the best indication of early life stage survival and recruitment. Juvenile sturgeon (age-3+) would be sampled with setlines. Sampling smaller sturgeon (age-1+) with small-mesh gill nets would also be attempted; however, the overall use and efficiency of this gear may be hampered by river drift of aquatic macrophytes and limited to low-velocity habitats. Still, the use of multiple kinds of gear provides us the opportunity to effectively sample a wide range of riverine habitats. To monitor spawning success under varying hydrologic year types, IPC would conduct this study over several years.

8.1.1.4. Implementation Schedule Within two years after a new license was issued for the Shoshone Falls Project, IPC would initiate sampling efforts to fit reproductive adults with radio transmitters prior to spawning periods. Because of population demographics in 2001, we anticipate that increasing number of spawners would be available for tagging and monitoring by 2005–2006. We would accomplish egg sampling by deploying artificial substrate mats at spawning locations during spring months when water temperatures were suitable for spawning. This task may require several years of observations to determine the adequacy of spawning over a range of hydrologic year types. Evaluations would also depend on availability of reproductive adults within the population at the

56 Idaho Power Company Snake River White Sturgeon Conservation Plan time of sampling. Depending on hydrologic year types, spawning success, growth rates of progeny, and initial fish lengths susceptible to collection gear, we anticipate that at least three to five years may be required before results of juvenile sampling efforts can be used for evaluating recruitment trends.

8.1.1.5. Cost Estimate The cost of monitoring spawning and recruitment success of white sturgeon over the course of a five-year period is estimated at $488,000.

8.1.2. Develop Experimental Conservation Aquaculture Program

8.1.2.1. Justification Conservation aquaculture represents an adaptive approach that prioritizes preservation of wild populations, along with their locally adapted gene pools, phenotypes, and behaviors (Anders 1998). Sturgeon conservation aquaculture has been implemented in the Kootenai River (USFWS 1999) and is being explored as a potential means for rebuilding sturgeon populations in the upper reaches of the Columbia River basin (UCWSRI 2002). Evaluations of released hatchery-produced sturgeon species in several systems indicate that hatchery-produced sturgeon can survive to adulthood and contribute to fisheries and spawning populations, particularly in depressed populations (Secor et al. 2000, Smith et al. 2002). Demographic modeling suggests that using hatchery-produced fish might be an effective means to restore populations because survival rates at critical early life stages can be increased manyfold over wild survival rates (Gross et al. 2002). Also, abundances can be more rapidly recovered because degraded and lost spawning and nursery habitats can be “circumvented” by rearing early life stages in artificial environments (Ireland et al. 2002).

The IDFG’s fisheries management plan for 2001–2006 lists five policies governing white sturgeon management in Idaho. One is that “Sturgeon populations may be supplemented with native stocks where necessary to maintain future management options, to research survival rates, or to utilize suitable rearing habitat where natural recruitment does not exist” (IDFG 2001). On an experimental basis, limited numbers of hatchery-propagated white sturgeon (from broodstock collected in the Bliss–C.J. Strike reach) have been released in several reaches of the Snake River, including the Shoshone Falls–Upper Salmon Falls reach. A total of 1,208 hatchery sturgeon were stocked in the Shoshone Falls–Upper Salmon reach between 1989 and 1997 (Table 10). Overall, stocking efforts in this reach appear to have been quite successful regarding abundance, growth, and survival rates of the hatchery fish. Survey results from the 2001 population assessment showed that condition factor, growth, and survival rates of these hatchery fish were comparable to those observed in wild sturgeon populations below Bliss and Hells Canyon dams (Lepla et al. 2002).

Therefore, a potential application for conservation aquaculture in the Snake River could be periodic supplementation of the Shoshone Falls–Upper Salmon Falls reach to maintain population size and genetic variability if natural recruitment could not be obtained under existing habitat conditions and population demographics. Hatchery-spawned and reared offspring from wild adults could be used as a potential tool to bypass current recruitment bottlenecks and

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replace failed natural recruitment. Although applying conservation aquaculture holds promise for sturgeon, such programs are largely experimental and should remain adaptive as they have yet to demonstrate long-term effectiveness in preserving sturgeon populations. Using hatchery programs may prove to be effective for restoring juvenile and adult abundances; however, there is still no guarantee that such efforts would always catalyze natural recovery. Restoring habitats suitable for natural recruitment would also be required (Secor et al. 2002).

The decision to develop a conservation aquaculture program for the Shoshone Falls–Upper Salmon Falls reach would depend on results from section 8.1.1. and on management directives from the IDFG. If study results show that natural recruitment could not be attained under existing habitat conditions and/or that potential to improve upon existing habitat impairments would not be feasible, then opportunities to develop a conservation aquaculture program in cooperation with the IDFG may be investigated.

8.1.2.2. Objective Maintain population abundance and genetic variability of white sturgeon in the Shoshone Falls– Upper Salmon Falls reach using conservation aquaculture.

8.1.2.3. Description A conservation aquaculture program should ensure measures that minimize both the genetic risks to existing wild sturgeon populations and the demographic risks to the productivity of source populations by removing broodstock. Careful design of broodstock collection, mating protocols, and release numbers should be considered to balance family groups and avoid genetic swamping. Also, protocols should include measures that minimize the risk of inbreeding and the potential for selecting maladaptive traits in released sturgeon. Periodic population assessments (section 8.1.3.) would also be required to determine whether the hatchery program produces the intended benefits and to provide information for adaptive management of the program as it unfolds. Effective monitoring would require marking hatchery fish internally with unique PIT tags and possibly externally by removing scutes in various patterns. The marking regiment should allow researchers to differentiate between release groups and assist with evaluating survival rates, condition factor, growth rates, and other data. The plan should also incorporate rigorous fish health protocols to limit disease risks in hatchery and wild fish. It may also be useful to conduct a review of “lessons learned” by others who have implemented a conservation hatchery program for sturgeon species.

Specific components for developing a conservation aquaculture program may include tasks such as those identified in the recovery plan for the Kootenai River population of white sturgeon (USFWS 1999): • Develop genetic preservation guidelines (i.e., breeding plan) for broodstock collection and mating design options

• Determine suitable source population(s) for broodstock collection

• Develop appropriate broodstock collection protocols

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• Determine appropriate production goals

• Develop fish health plan for hatchery-reared white sturgeon

• Develop tagging protocols to differentiate hatchery-reared white sturgeon from wild stocks

• Develop release plans

• Develop policy for hatchery-reared white sturgeon produced in excess of program needs

• Develop monitoring plans to evaluate performance and contribution of hatchery-released white sturgeon

Existing facilities and sturgeon culture expertise at the College of Southern Idaho in Twin Falls could be suitable resources for spawning and rearing hatchery-produced white sturgeon.

8.1.2.4. Implementation Schedule Following the issuance of a new license for the Shoshone Falls Project, the decision to develop a conservation aquaculture program would depend on study results from section 8.1.1. and management directives from the IDFG. For planning purposes, a conservation aquaculture program would be conducted on an experimental basis for a period of five years with the goal of increasing population abundance. After that time, a population assessment (section 8.1.3.) would be conducted to determine whether conservation aquaculture had provided intended benefits and should be continued or alternative mitigation measures were warranted.

8.1.2.5. Cost Estimate The costs associated with this measure would depend on the level of production and the duration required to meet program goals as outlined in section 8.1.2.3. For cost estimation at this time, we considered two people sampling for up to three months (February to April) a reasonable effort to capture broodstock consisting of at least one female and two or more male sturgeon. We also assumed two family groups of 500 fish per family to calculate the facility costs (feed, labor, PIT tags, and others) associated with spawning and rearing of progeny for one year prior to stocking. Based on these assumptions, the annual cost associated with broodstock collection and rearing of progeny for one year is estimated at $84,000. For planning purposes, the cost to support an experimental conservation aquaculture program over a five-year period in the Shoshone Falls– Upper Salmon Falls reach is estimated at $420,000.

8.1.3. Conduct Periodic Population Assessments

8.1.3.1. Justification The white sturgeon population between Shoshone Falls and Upper Salmon Falls Dam currently ranks as the fourth largest sturgeon population (based on the 95% CI) in the Snake River, although 94% of the population is currently made up of hatchery-propagated fish (Lepla et al. 2002). Survey results show that condition factor, growth, and survival rates of these hatchery fish are comparable to those observed in wild sturgeon populations below Bliss and Hells Canyon

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dams. Periodic population assessments would be used to continue evaluations between hatchery and wild stocks and to monitor temporal changes in population demographics. Population assessments would be conducted at least every ten years. Incorporating monitoring results into the PVA model would also be used to evaluate anticipated population demographics and refine risk/benefit predictions. Population assessments would also provide valuable feedback to resource agencies and help them develop future management policies for Snake River white sturgeon populations.

8.1.3.2. Objective Monitor population status of white sturgeon in the Shoshone Falls–Upper Salmon Falls reach of the Snake River.

8.1.3.3. Description IPC would monitor population demographics—including abundance, population structure, and temporal trends—by periodically assessing populations. Population assessments would be conducted using standardized collection gear (setlines and gill nets) and sampling protocols consistent with previous IPC sturgeon surveys. Captured sturgeon would be examined for PIT tags to distinguish between wild and hatchery stocks. All unmarked fish would be fitted with 125-kHz PIT tags, and scute removal patterns would serve as permanent external marks. Surveys would rely on mark-recapture sampling to determine population abundance and would include collection of biological (abundance, maturation, growth, and survival rates) and genetic (section 8.1.4.) information so that population productivity could be evaluated.

8.1.3.4. Implementation Schedule The timing of population assessments may depend on results of implementing the measures described in sections 8.1.1. and/or 8.1.2. For planning purposes, periodic population assessments would be conducted at ten-year intervals for the duration of a new license for the Shoshone Falls Project.

8.1.3.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals over the course of a new 30-year license for the Shoshone Falls Project is estimated at $311,000.

8.1.4. Monitor Genotypic Frequencies

8.1.4.1 Justification Sturgeon require a mosaic of habits to complete all life stages. Many of the artificially created bounds that have been placed on these fish have acted to reduce the effective population size of sturgeon within such areas. This loss in effective population size leads to the potential loss of genetic variation by inbreeding and genetic drift, which may both contribute to a population decline (Jager et al. 2001b). Although current evidence suggests that no significant genetic differences exist among Snake River white sturgeon (P. Anders, personal communication),

60 Idaho Power Company Snake River White Sturgeon Conservation Plan effective long-term management requires that genetic diversity be monitored as one of the potential population responses to proposed mitigation measures. For example, a potential measure should favorably affect, or at least not reduce genetic variability and diversity of, the recipient population. Similarly, if a measure involves a source population (such as translocation or aquaculture), the source population should not be impaired.

Five dams (and approximately 250 river miles) separate the two Snake River reaches that support self-sustaining populations. These populations are likely to be drawn upon to help rebuild other Snake River reaches. One of the guiding principles in determining appropriate PM&E measures was to protect these stronghold populations from risk. A shift in the genotypic frequency within these sturgeon populations is possible as new individuals are incorporated into them or as individuals are removed from them to supplement other reaches. Because these two populations currently provide self-sustaining recruitment, they offer the greatest means of identifying trends in genetic integrity.

The measure of developing a program to monitor genetics would apply to all reaches of the Snake River from Shoshone Falls to Lower Granite Dam. The plan would primarily monitor and track any changes to the genotypic frequencies within each subpopulation with the intent of identifying potential genetic bottlenecks before they occur. This plan would use present data as a baseline. In the future, genetic data would be collected as part of the population assessments conducted for each reach.

8.1.4.2. Objective Monitor genotypic frequencies of Snake River white sturgeon between Shoshone Falls and Lower Granite dams.

8.1.4.3. Description IPC, with input from qualified geneticists, would continue to monitor genotypic frequencies of Snake River white sturgeon for comparison with current information. This program would use existing wild juvenile and adult white sturgeon genetics information, collected by IPC during the 1996–2001 field seasons, as a baseline data set. The levels of genetic diversity found within and among the various reaches of the Snake River would help establish desired future conditions for each reach.

The most recent genetic information for Snake River white sturgeon was collected by IPC and analyzed at the University of Idaho (Anders and Powell 1999, 2002; Anders et al. 2000). Only those reaches where significant reproduction was known to occur (Bliss–C.J. Strike and Hells Canyon–Lower Granite populations) were used in the analysis. Additional IPC samples collected from other Snake River reaches would be analyzed and interpreted to further establish the baseline for genetic diversity. Future collections would target the progeny or subsequent generations of the fish that were included in the baseline data set. Under natural conditions, we would not expect any changes in genotypic frequencies to occur within the period of a new project license or an even longer period. However, implementation of some measures (e.g., translocation) may potentially alter genetic frequencies and increase diversity at a faster rate than what might naturally occur. Other potential measures, such as amplifying successful

61 Snake River White Sturgeon Conservation Plan Idaho Power Company family group genes through artificial propagation, may decrease genetic diversity. Identifying such measures and their future potential for maintaining or enhancing genetic diversity is key to implementing a successful plan.

Data collection would include collecting a small (1-cm2) amount of fin tissue from sturgeon following an agreed-upon sampling regime. Geneticists from the Center for Salmonid and Freshwater Species at Risk at the University of Idaho or another qualified facility would process (extract DNA) and interpret the results.

8.1.4.4. Implementation Schedule As new licenses were issued for IPC projects, monitoring genotypic frequencies of Snake River sturgeon populations would be conducted concurrently with periodic population assessments between Shoshone Falls and Lower Granite dams.

8.1.4.5. Cost Estimate The cost of monitoring genotypic frequencies of Snake River white sturgeon in reaches between Shoshone Falls and Lower Granite dams over the duration of new project licenses is estimated at $154,000.

8.1.5. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects

IPC monitors temperature and DO at Shoshone Falls, Upper Salmon Falls, Lower Salmon Falls, and Bliss dams as required by the § 401 water quality certification and consent order filed with the FERC on June 17, 1998 (FERC 2002a). In addition, the following measures have been implemented by IPC as required by the certification and consent order:

• Annually assist ($15,000 per year) in further development and implementation of the Idaho Department of Environmental Quality’s (IDEQ) middle Snake River watershed management plan/total maximum daily load (TMDL).

• Provide funding ($3,000,000 one time) for acquisition of spring resources on the middle Snake River to protect and enhance water quality and aquatic species habitats.

• Provide funding ($750,000 one time) for design, development, and construction of artificial wetlands, settling ponds, and other systems and facilities to prevent or reduce nutrients and sediments from entering the middle Snake River.

• Annually provide funding ($50,000 per year for ten years) to IDEQ for monitoring of long- term water quality conditions and changes.

The following measures have not been implemented at this time but are required to be implemented after the FERC licenses are issued:

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• Design, install, and operate equipment at the Upper Salmon Falls, Lower Salmon Falls, and Bliss projects to remove aquatic vegetation collected on trash racks.

• Maintain a minimum flow of 50 cfs in the North Channel at Upper Salmon Falls.

While white sturgeon populations in the middle Snake River may benefit from measures implemented in § 401 water quality certification, the above actions are part of the TMDL and § 401 water quality certification processes and considered outside the immediate scope of the WSCP. Therefore, measures and costs associated with water quality improvements as identified within the TMDL and § 401 water quality certification processes are not included in the WSCP. Information on temperature and DO would be available through the reporting process to FERC and IDEQ.

8.1.6. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 64.

8.2. Upper Salmon Falls–Lower Salmon Falls Reach

8.2.1. Conduct Periodic Population Assessments

8.2.1.1. Justification The presence of white sturgeon in the Upper Salmon Falls–Lower Salmon Falls reach is questionable (see status review in section 4.2.2.). PVA model simulations have suggested that the sturgeon population in the Upper Salmon Falls–Lower Salmon Falls reach would not be self- supporting but would depend on upstream occurrences for benefits to the population. At present, we suspect that downstream movement of white sturgeon from the Shoshone Falls–Upper Salmon Falls sturgeon population may be low, based on the high retention and abundance of hatchery sturgeon sampled there (see section 4.1.2.) and the absence of these hatchery fish during population assessments below Lower Salmon Falls and Bliss dams. However, changes in sturgeon abundance and population structure of the Upper Salmon Falls–Lower Salmon Falls population may occur as recruitment to the Shoshone Falls–Upper Salmon Falls population improves and fish disperse downstream. Increased recruitment in the Shoshone Falls–Upper Salmon Falls sturgeon population may occur naturally as more hatchery sturgeon mature and spawn or through potential future supplementation efforts (section 8.1.2.). Therefore, periodic population assessments in the Upper Salmon Falls–Lower Salmon Falls reach would be conducted primarily to monitor future population responses that may occur as a result of changes in the Shoshone Falls–Upper Salmon Falls sturgeon population.

8.2.1.2. Objective Monitor population status of white sturgeon in the Upper Salmon Falls–Lower Salmon Falls reach of the Snake River.

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8.2.1.3. Description Population assessment would be conducted using methods described in section 8.1.3.3.

8.2.1.4. Implementation Schedule A population assessment would be conducted within one year after a new license were issued for the Upper Salmon Falls Project. The initial population assessment would be used to determine the existing population status and serve as a baseline for comparison. For planning purposes, future population assessments in the Upper Salmon Falls–Lower Salmon Falls reach would be conducted at ten-year intervals for the duration of a new project license for the Upper Salmon Falls Project. However, the frequency of future population monitoring may be dictated by results from the initial population assessment and/or coordinated with population assessments in the Shoshone Falls–Upper Salmon Falls reach to evaluate population responses for these two adjacent reaches.

8.2.1.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals over the course of a new 30-year license for the Upper Salmon Falls Project is estimated at $183,000.

8.2.2. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.2.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects

See section 8.1.5. for a description of this proposal.

8.2.4. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 64.

8.3. Lower Salmon Falls–Bliss Reach

8.3.1. Conduct Periodic Population Assessments

8.3.1.1. Justification IPC would conduct periodic population assessments to monitor temporal changes in population demographics and allow for evaluation of proposed mitigation measures. For the Lower Salmon Falls–Bliss reach, population assessments would also include evaluation of both wild and hatchery stocks.

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Between 1989 and 1994, a total of 2,560 hatchery-propagated sturgeon were stocked in the Lower Salmon Falls–Bliss reach. However, study results from the 1992–1993 population assessment (Lepla and Chandler 1995b) suggest that stocking hatchery sturgeon in the Lower Salmon Falls–Bliss reach may not have been as successful as stocking in the Shoshone Falls– Upper Salmon Falls reach. About twice as many hatchery sturgeon were released in the Lower Salmon Falls–Bliss reach than were released in the Shoshone Falls–Upper Salmon reach (n = 1,208); however, only 33 hatchery sturgeon were captured in the Lower Salmon Falls–Bliss reach during 1992–1993. While low captures may have been related in part to sampling gear efficiencies, observed growth and survival rates of hatchery sturgeon in the Shoshone Falls– Upper Salmon Falls reach suggest that more hatchery sturgeon have been available for capture below Lower Salmon Falls Dam.

Based on current assumptions, restoration efforts for the Lower Salmon Falls–Bliss reach may be constrained by habit limitations due to the short length of the reach and the downstream export of sturgeon. Translocation and/or conservation aquaculture may be potential tools for population restoration efforts below Lower Salmon Falls Dam. However, the contribution that historical stocking efforts have made toward increasing abundance and population productivity in the Lower Salmon Falls–Bliss reach remains largely unknown and should be evaluated as part of the next population assessment before future actions are determined. Based on the population assessment results, potential measures for the Lower Salmon Falls–Bliss reach would then be reviewed with the WSTAC.

8.3.1.2. Objective Monitor status of wild and hatchery stocks of white sturgeon in the Lower Salmon Falls–Bliss reach of the Snake River.

8.3.1.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.3.1.4. Implementation Schedule A population assessment of the Lower Salmon–Bliss reach would be implemented within one year after a new license was issued for the Lower Salmon Falls Project to determine the current status and contribution from historical stockings of hatchery white sturgeon. For planning purposes, future population assessments would be conducted at ten-year intervals for the duration of the new license for the Lower Salmon Falls Project.

8.3.1.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals over the course of a new 30-year license for the Lower Salmon Falls Project is estimated at $253,000.

8.3.2. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

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8.3.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects

See section 8.1.5. for a description of this proposal.

8.3.4. Develop Schematic Flow Chart for PM&E Measures

See Figure 64.

8.4. Bliss–C.J. Strike Reach

8.4.1. Conduct Periodic Population Assessments

8.4.1.1. Justification The Bliss–C.J. Strike sturgeon population is the second largest in Idaho and the only self- sustaining white sturgeon population in the Snake River upstream of Hells Canyon Dam. Although population assessments from 1979–1981 (Cochnauer 1981), 1991–1993 (Lepla and Chandler 1995a), and 2000 (IPC unpublished data) have documented variable recruitment trends within the population, overall, this population is considered genetically diverse (M. Powell; University of Idaho; personal communication to the WSTAC, August 8, 2002) and productive, based on the wide range of size classes from juveniles to reproducing adults. Growth rates and relative weights are some of the highest observed in the Snake River. Because of these conditions, we place high importance on maintaining this stronghold population and emphasize that actions conducted within this reach and/or adjacent reaches should not threaten the viability and persistence of this population. While mitigation measures proposed in the WSCP are intended to improve Snake River white sturgeon populations, unforeseen consequences could occur that would dictate the need for regular population monitoring.

Population monitoring in the Bliss–C.J. Strike reach would be accomplished by periodic stock assessments. Past population assessments have been conducted at roughly ten-year intervals; therefore, conducting a population assessment within the next few years would be consistent with the timing of the previous two surveys. Also, initiating a survey at this point would establish a current baseline from which to compare future population responses as mitigation measures develop for the Bliss–C.J. Strike and C.J. Strike–Swan Falls reaches. Specifically, translocation (section 8.5.1.) of reproductive-sized sturgeon from below C.J. Strike Dam to the Bliss– C.J. Strike reach has been proposed as a method to provide spawners access to suitable spawning habitats. We anticipate that this measure would provide benefits to both populations. Therefore, population assessments in the Bliss–C.J. Strike reach should initially coordinate with efforts described in section 8.5.1. so that the benefits of translocation could be evaluated from detected changes in sturgeon productivity.

Although the implementation and timing of population assessments would be contingent upon new project license being issued, for planning purposes, a population assessment would be conducted in the Bliss–C.J. Strike reach during 2004–2005 and serve as baseline for future

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population comparisons. A second population assessment would be conducted within 10 to 12 years to correspond with the timing of a population assessment of the C.J. Strike–Swan Falls sturgeon population (section 8.5.4.). Coordinating the timing of these two population assessments would provide complementary information to assist evaluations of translocation. Although the timing of future population assessments would largely depend on the outcome of measures determined through survey results, for planning purposes, future population assessments in the Bliss–C.J. Strike reach would be conducted at approximately ten-year intervals for the duration of the new licenses for the Bliss and C.J. Strike projects.

Population assessments would be important for evaluating the effectiveness of implemented measures and determining whether alternative mitigation measures were warranted. Incorporating monitoring results into the PVA could also be used to evaluate anticipated population demographics and refine risk/benefit predictions. Population assessments would also provide valuable feedback to resource agencies that are developing future management policies for Snake River white sturgeon populations.

8.4.1.2. Objective Monitor population status of white sturgeon in the Bliss–C.J. Strike reach of the Snake River.

8.4.1.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.4.1.4. Implementation Schedule A population assessment of the Bliss–C.J. Strike reach would be implemented within a year after a new license were issued for the Bliss Project. A second population assessment would be conducted within 10 to 12 years following completion of translocation efforts for Phase 2 (section 8.5.1.). Future monitoring intervals would depend on these survey results and whether alternative mitigation measures were implemented at that time. However, for planning purposes, population assessments would be conducted at ten-year intervals for the duration of a new license for the Bliss Project.

8.4.1.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals over the course of a new 30-year license for the Bliss Project is estimated at $552,000.

8.4.2. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.4.3. Monitor Response to Measures Implemented for § 401 Water Quality Certification for the Mid-Snake Projects

See section 8.1.5. for a description of this proposal.

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8.4.4. Improve Water Quality in C.J. Strike Reservoir by Developing Specific Measures through the C.J. Strike TMDL

The IDEQ has designated C.J. Strike Reservoir as water quality limited, or not supporting beneficial uses as defined by State of Idaho water quality standards. The listed pollutants of concern were nutrients and pesticides. In addition, DO and temperature in C.J. Strike Reservoir do not always meet numeric state standards. The IDEQ has initiated the TMDL development process for the C.J. Strike Project area, with expected completion by 2004. And the IDEQ has issued a § 401 water quality certificate for the C.J. Strike Project. As part of certification, IPC is providing $50,000 annually for TMDL development and, after completion of the TMDL, will cooperate and implement measures to achieve IPC allocations. Since the above actions are part of the TMDL and § 401 water quality certification processes, they are considered outside the immediate scope of the WSCP. Therefore, measures and costs associated with water quality improvements for C.J. Strike Reservoir are not included in the WSCP.

8.4.5. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 64.

8.5. C.J. Strike–Swan Falls Reach

8.5.1. Translocate Reproductive-Sized Adults below C.J. Strike Dam to Spawning Habitat in the Bliss–C.J. Strike Reach

8.5.1.1. Justification Field surveys conducted in 1989 (IDFG 1992), 1994–1996 (Lepla and Chandler 1997), and 2001 (IPC unpublished data) have shown that the C.J. Strike–Swan Falls population consists mostly of mid-sized and large sturgeon and that population structure has not changed appreciably over the past decade. The continued low abundance of smaller sturgeon (less than 92 cm TL) suggests that spawning is largely unsuccessful below C.J. Strike Dam and that the population is probably supported via recruitment from the more abundant sturgeon population immediately upstream in the Bliss–C.J. Strike reach.

An instream flow study conducted below C.J. Strike Dam showed that limited spawning habitat was available only during periods of high flow (Chandler and Lepla 1997). As flows decreased from 15 to 20 kcfs, habitat rapidly became less suitable, with little or no suitable spawning conditions available at flows between 5 and 10 kcfs. Study results showed that project operations affect spawning habitat mostly during low- and normal-flow years. In 2001, IPC conducted a follow-up survey to evaluate recruitment levels in response to more normal and above-normal flows (1996–1999) in the middle Snake River. Despite the occurrence of high-flow years, no increase in the number of small sturgeon was observed below C.J. Strike Dam. These results contrasted with the post-drought recruitment trends observed upstream in the Bliss–C.J. Strike reach, where numbers of small sturgeon increased from 2 to 6% in 1991–1993 to 45% in 2000. Therefore, this latest survey implies that physical habitat below C.J. Strike Dam may not be

68 Idaho Power Company Snake River White Sturgeon Conservation Plan

adequate to support sturgeon natural production even during high-flow years and that the C.J. Strike–Swan Falls sturgeon population may be supported primarily by downstream recruitment of sturgeon from the Bliss–C.J. Strike population.

The overall low gradient and lack of turbulent runs in the C.J. Strike–Swan Falls reach suggest that white sturgeon probably spawned historically in other sections of the Snake River. White sturgeon spawning and incubation areas below Bliss, Swan Falls, and Hells Canyon dams are located within the narrow canyon sections of the Snake River and are associated with turbulent pools, high-velocity runs, and nearby rapids (Lepla and Chandler 2001). Because the C.J. Strike– Swan Falls reach does not provide these habitats, transporting reproductive-sized adults upstream to the Bliss–C.J. Strike reach would provide these fish access to suitable spawning and rearing conditions and would “recapture” lost reproductive potential and reestablish upstream gene flow.

Model simulations of population viability show that the translocation of sturgeon from below C.J. Strike Dam provides substantial benefit to the Bliss–C.J. Strike population. Enhancing sturgeon productivity upstream could also benefit recruitment to the C.J. Strike–Swan Falls population as increasing numbers of fish move downstream. Field survey results, based on recovery of tagged individuals, have shown that sturgeon from the Bliss–C.J. Strike reach successfully emigrate downstream into the C.J. Strike–Swan Falls reach. However, model simulations also highlight the importance of maintaining a downstream subsidy of sturgeon so that translocation does not adversely affect the C.J. Strike–Swan Falls sturgeon population. Population monitoring (section 8.5.4.) and evaluation of sturgeon entrainment at C.J. Strike Dam (section 8.5.3.) would also be necessary to monitor the overall effectiveness of translocation.

Augmenting or restoring connections that allow white sturgeon to access habitats in other reaches could potentially be accomplished by other alternatives. However, translocation is currently the most feasible option for achieving the desired objective of providing reproductive- sized sturgeon below C.J. Strike Dam with access to suitable spawning habitats in the Bliss– C.J. Strike reach. The capture and transport of sturgeon can be accomplished with existing technology and presents the most reliable solution for passing sturgeon. To mitigate for lost recruitment and passage, the ODFW has successfully used capture-and-transport techniques for transporting white sturgeon among lower Columbia River reservoirs (Rien and North 2002).

8.5.1.2. Objective Increase white sturgeon recruitment to the C.J. Strike–Swan Falls reach by enhancing sturgeon productivity in the Bliss–C.J. Strike reach via translocation of reproductive-sized adult sturgeon.

8.5.1.3. Description Translocation of sturgeon from the C.J. Strike–Swan Falls reach to the Bliss–C.J. Strike reach would be conducted on an experimental basis and use a two-phased approach.

Phase 1—IPC expects that translocation would be effective in relocating reproductive adults between reaches without affecting their spawning performance. Therefore, this effort is designed to evaluate the behavior and spawning success of adults that have been transported to the Bliss– C.J. Strike reach. Sampling efforts would initially focus on adult sturgeon in the final stages of maturation between late winter and early spring. Targeting this life stage would enable

69 Snake River White Sturgeon Conservation Plan Idaho Power Company monitoring efforts to focus specifically on spawning behavior, reduce the probability of tag loss before spawning activities occur, and facilitate recovery of tagged fish for post-spawn inspection.

During Phase 1, biologists would attempt to capture and transport up to four reproductive female (late vitellogenic and/or vitellogenic) and four reproductive male sturgeon each year for two years (n = 16). Use of collection gear and sampling protocols would be consistent with previous IPC sturgeon surveys to safely capture and minimize stress to sturgeon. All captured fish would be measured, weighed, and fitted with a PIT tag. Both sex and stage of gonad maturation would be determined by surgical biopsy (Conte et al. 1988), with immature fish being released back into the river. Female and male sturgeon showing reproductive readiness would be transferred directly from the boat to a trailer- or truck-mounted transport tank stationed at an access ramp along the river. Sturgeon would be tagged with radio transmitters and transported upstream to selected release points in the Bliss–C.J. Strike reach where staging and spawning activities are known to occur. Radio telemetry would then be used to monitor the behavior of transported individuals during staging and spawning periods. Biologists would attempt to recapture these individuals during post-spawn periods to surgically confirm whether they had spawned. Depending on our success at capturing reproductively mature sturgeon, the environmental conditions present during spawning, success of tracking telemetered individuals, and the subsequent recapture of post-spawn sturgeon, we anticipate that two to four years may be required to complete this initial phase.

Phase 2—If transported sturgeon are confirmed to spawn in the Bliss–C.J. Strike reach, translocation efforts would switch from sampling reproductively mature adults to collecting reproductive-sized sturgeon (greater than 160 cm TL10), regardless of maturity. Switching translocation efforts to reproductive-sized sturgeon would reduce the sampling pressure and repeated handling of sturgeon that otherwise would be required to annually “mine” the population for maturing adults. Although habitat evaluations and population assessments have shown that spawning and recruitment are largely unsuccessful below C.J. Strike Dam, this practice would also allow for some spawners to remain within the C.J. Strike–Swan Falls population and perhaps provide for some natural production to occur on a limited basis.

Translocation efforts during Phase 2 would be conducted annually for a period of ten years. Lepla and Chandler (1997) estimated that 7 female sturgeon were expected to spawn annually below C.J. Strike Dam. Based on this estimate, up to 14 sturgeon (7 females and 7 males) would be transported annually to the Bliss–C.J. Strike reach. Given that sex ratios in the C.J. Strike– Swan Falls population were approximately 50:50, attempts would be made to maintain this sex ratio of transported fish. Noninvasive procedures, such as those used to recognize sex steroids, may be used to identify the sex of transported individuals.11 Another option, based on the underlying assumption that males and females have equal chance of being sampled, may be to transport the first 14 sturgeon captured (greater than 160 cm).

Upon completion of Phase 2, population assessments would be conducted in the C.J. Strike– Swan Falls (section 8.5.4.) and Bliss–C.J. Strike (section 8.4.1.) reaches to determine whether

10 The smallest reproductive female sturgeon that IPC has identified during sturgeon surveys in the Snake River. 11 Oregon State University is currently researching methods to identify the sex and stage of white sturgeon by using blood plasma indicators, sex steroids, and calcium.

70 Idaho Power Company Snake River White Sturgeon Conservation Plan translocation had provided intended benefits and should be continued or whether alternative mitigation measures were warranted. While the time required for population responses is uncertain, monitoring at this point would be prudent to ensure that unintended consequences were not occurring in either population. For instance, model simulations of population viability have shown that translocation can impact donor populations if transport targets are set too high (i.e., too many individuals are removed). As a measure of protection, translocation polices would be based on sampling effort and not on “quotas” to prevent removal of too many individuals from the C.J. Strike–Swan Falls population. For instance, this target effort could be estimated by determining the amount of sampling effort required to capture 14 reproductive-sized sturgeon (greater than 160 cm TL) in past surveys below C.J. Strike Dam and could be used as a strict limit on annual fishing effort.

8.5.1.4. Implementation Schedule Translocation efforts would be implemented within one year after a new license were issued for the C.J. Strike Project. Phase 1 efforts would operate on an experimental basis for two to four years to determine whether transported adults spawn in the Bliss–C.J. Strike reach. If spawning were confirmed, translocation efforts would continue on an annual basis (Phase 2) for a period of ten years. After that time, the feasibility of translocation to enhance upstream productivity and recruitment would be reviewed based on population assessments in the Bliss–C.J. Strike and C.J. Strike–Swan Falls reaches. If study results indicate feasibility, the translocation efforts would continue on an annual basis for the duration of the new license for the C.J. Strike Project, with periodic review based on future population assessments.

8.5.1.5. Cost Estimate The cost of conducting a translocation program for the duration of a new 30-year license for the C.J. Strike Project is estimated at $578,000.

8.5.2. Determine Feasibility of Developing Spawning and Incubation Habitats

8.5.2.1. Justification The low abundance of small sturgeon sampled during past population assessments suggests that spawning has largely been unsuccessful below C.J. Strike Dam. The overall low gradient and lack of turbulent runs in the C.J. Strike–Swan Falls reach lead us to believe that white sturgeon probably spawned historically in other sections of the Snake River. For instance, white sturgeon spawning and incubation areas in the canyon sections below Bliss, Swan Falls, and Hells Canyon dams are often associated with turbulent pools, high-velocity runs, and nearby rapids (Lepla and Chandler 2001). An instream flow study conducted below C.J. Strike Dam showed that very little spawning habitat was available and that it occurred only during periods of high flow (Chandler and Lepla 1997). As flows decreased from 15 to 20 kcfs, habitat rapidly became less suitable, with little or no suitable spawning conditions available between 5 and 10 kcfs. Creating additional areas suitable for spawning and incubating life stages may bolster future productivity levels in this population.

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Initiation of this measure would depend on results obtained from activities described in sections 8.5.1. and 8.5.4. If study results indicated that translocation would not be an effective way to increase recruitment to the C.J. Strike–Swan Falls reach, then feasibility of constructing spawning and incubation habitats below C.J. Strike Dam would be evaluated.

8.5.2.2. Objective Determine feasibility of developing spawning and incubation habitats to enhance sturgeon productivity in the C.J. Strike–Swan Falls reach.

8.5.2.3. Description The proposed measure would be designed to evaluate the engineering feasibility and biological effectiveness of creating habitat conditions suitable for spawning and incubation life stages. Evaluations may include alternatives such as concrete or rock-fill wing dams that constrict the river channel and flow. Such constriction increases velocity and turbulence, both commonly associated with spawning and incubation areas in other reaches of the Snake River. An engineering-based evaluation would be necessary to determine feasibility of various alternatives, the construction requirements, and project operations needed to create habitat conditions suitable for spawning and incubation.

8.5.2.4. Implementation Schedule The decision to conduct a feasibility study for developing spawning and incubation habitats below C.J. Strike Dam would depend on review of study results from translocation (section 8.5.1.) and population assessments (section 8.5.4.). For planning purposes, we anticipate that one to two years may be required to complete this feasibility study.

8.5.2.5. Cost Estimate The cost of conducting a feasibility study for developing spawning and incubation habitats below the C.J. Strike Project is estimated at $100,000.

8.5.3. Determine Feasibility of Reducing Trash Bar Spacing

8.5.3.1. Justification Downstream passage of white sturgeon at C.J. Strike Dam has been documented by recovery of individuals, marked with PIT tags, that had been previously captured or stocked (i.e., hatchery fish) upstream of this dam. During a 1994–1996 population assessment of the C.J. Strike– Swan Falls reach, a total of 6 sturgeon (4 wild and 2 hatchery fish) were captured below C.J. Strike Dam, individuals that were originally observed in the Bliss–C.J. Strike reach (Lepla and Chandler 1997). Based on recovery of these tags below C.J. Strike Dam and the fraction of marked fish in each of these reaches, approximately 2%, or 53 sturgeon, are estimated to pass C.J. Strike Dam annually. Habitat and population evaluations below C.J. Strike Dam also suggest that this population is currently supported by recruitment from the more abundant sturgeon population upstream in the Bliss–C.J. Strike reach.

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The current trash bar spacing at C.J. Strike Dam potentially allows for sturgeon up to approximately 200 cm TL to enter penstocks that route water to the turbines. Fish greater than 80 cm are potentially subject to 100% probability of blade strike when attempting to pass through the turbines, although the absence of dead or moribund sturgeon below C.J. Strike currently suggests that turbine passage and the potential for turbine-related mortality may be low. Of the sturgeon recaptured below C.J. Strike Dam, four were relatively large (121–211 cm TL) but capable of being entrained with high turbine blade strike probabilities (100%): these individuals probably passed the dam during spill events. IPC personnel observed at least one sturgeon passing over the spillway at C.J. Strike Dam during a spring spill event. However, turbine passage and the potential for increasing mortality may occur at C.J. Strike Dam if translocation efforts (section 8.5.1.) were successful and increasing numbers of recruits moved downstream.

Model simulations of population viability have shown that reducing trash bar spacing at C.J. Strike Dam substantially increases the benefits of translocation and final population size within the Bliss–C.J. Strike reach. This situation in turn benefits sturgeon in the C.J. Strike– Swan Falls reach. The modeled results highlighted the importance of maintaining downstream recruitment to the C.J. Strike–Swan Falls population. Model simulations varying trash bar spacing suggested that there might be an optimal intermediate spacing that reduces the mortality of adult sturgeon but does not eliminate the upstream subsidy from the Bliss–C.J. Strike reach. Model results also indicated that interactions between population response and trash bar spacing can be complex and underscored the uncertainty of evaluating risks and benefits of this proposed measure.

Very little information is available on methods of preventing turbine entrainment of sturgeon. Two recent studies have demonstrated limited success using angled bar racks and louvers to guide juvenile sturgeon toward downstream conveyance routes. Amaral et al. (2001) found that 92.9 to 100% of juvenile shortnose sturgeon averaging about 1 ft long successfully guided along angled bar racks and louvers, but smaller (0.5 to 0.66 ft) lake sturgeon did not guide well at any of the approach velocities that were tested, which ranged from 1 to 3 ft/s. Kynard and Horgan (2001) reported similar guidance efficiencies of 67 to 100% for shortnose sturgeon ranging in length from 0.8 to 1.0 ft and 58 to 100% for pallid sturgeon ranging in length from 0.6 to 0.9 ft with an approach velocity of approximately 1 ft/s. Both studies were conducted in relatively small-scale laboratory settings. Whether these initial results can be effective in a full-scale application remains to be demonstrated. It is also unclear whether this information is applicable to white sturgeon.

Given model predictions and our current understanding of white sturgeon entrainment at C.J. Strike Dam, additional information regarding numbers of sturgeon, fish size, seasonal occurrence, and use of spillway and turbine routes should be investigated. Engineering feasibility and biological evaluations would also be needed to determine exclusion sizes and impingement potential of white sturgeon at varying trash bar spacing.

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8.5.3.2. Objective Determine feasibility of 1) using acoustic camera technology to evaluate entrainment potential of white sturgeon at C.J. Strike Dam and 2) reducing existing trash bar spacing so that it would prevent or minimize turbine entrainment without creating an impingement risk.

8.5.3.3. Description Recent advancements in acoustic camera technology using Dual-Frequency Identification Sonar (DIDSON) may be promising for evaluating white sturgeon entrainment at C.J. Strike Dam. This technology is currently being applied to fish passage research at large hydropower projects on the lower Columbia River (Moursund et al. 2002). While traditional sonar has sufficient range for fish studies, it lacks the acuity to accurately determine species, size, or shape of fish. Optical systems such as video cameras provide clearer pictures of fish but are hampered by low light or turbid water. The acoustic camera, however, can provide near-video-quality grayscale images regardless of turbidity and “noise” (i.e., air bubbles), which has impaired traditional sonar methods (Moursund et al. 2002).

Initially, field tests would be conducted at C.J. Strike Dam to determine the feasibility of applying acoustic camera technology to detect and identify fish species, including white sturgeon. If feasibility is confirmed, biologists would conduct annual monitoring of spillway gates and turbine intakes at C.J. Strike Dam during low, normal, and high hydrologic year types. Information regarding number and size of sturgeon, seasonal occurrence, and use of spillway and turbine routes would be examined. For planning purposes, data collection would require three or more years of monitoring, depending on annual snow-pack conditions, to evaluate low, normal, and high hydrologic years. Data collected during these varying hydrologic year types would be used to evaluate environmental conditions associated with downstream migration and entrainment potential of sturgeon. Population responses from entrainment would be evaluated using the PVA. Depending on study results, monitoring may be required at periodic intervals to evaluate future entrainment potential and/or effectiveness of modifying trash bar spacing.

Feasibility and effectiveness of reduced trash bar spacing at C.J. Strike Dam would be assessed by engineering and biological studies. An engineering-based evaluation would be necessary to determine construction requirements, approach velocities, and lost generation costs incurred (from head loss) across a range of flows and trash bar spacings. Biological evaluations of white sturgeon under laboratory settings would also be needed to determine sturgeon approach behavior, swimming performance, exclusion size, and impingement potential at varying trash bar spacing and approach velocities. This feasibility study would probably require two to three years for completion.

8.5.3.4. Implementation Schedule The feasibility of using acoustic camera technology to identify white sturgeon would be conducted within one year after a new license were issued for the C.J. Strike Project. If this study had a successful outcome, annual monitoring at turbine intakes and spillway bays would begin over varying hydrologic year types to determine environmental conditions associated with downstream migration and entrainment potential of sturgeon at C.J. Strike Dam. For planning purposes, initial monitoring efforts may require three or more years to obtain sufficient baseline

74 Idaho Power Company Snake River White Sturgeon Conservation Plan data on downstream movements associated with low, normal, and high hydrologic years. Future monitoring efforts may also be conducted at specified intervals (i.e., every five years) to evaluate future entrainment potential and population responses to mitigation measures such as translocation.

The feasibility study on modifying the trash bar spacing at C.J. Strike Dam may depend on results from acoustic camera monitoring. If monitoring results indicate that turbine entrainment of white sturgeon is occurring, then biological and engineering evaluations of various trash bar spacing to reduce turbine entrainment and impingement would be initiated. For planning purposes, we anticipate two years may be required to complete these evaluations.

8.5.3.5. Cost Estimate The cost of conducting a pilot study to determine whether acoustic camera technology could reliably identify white sturgeon is estimated at $20,000. If feasible, installing acoustic camera(s) at C.J. Strike Dam and monitoring for at least three years to collect baseline data on sturgeon entrainment is estimated at $438,000. Conducting a two-year study on the biological and engineering feasibility of modifying the trash bar spacing at C.J. Strike Dam is estimated at $316,000.

8.5.4. Conduct Periodic Population Assessments

8.5.4.1. Justification Past population assessments (1989, 1994–1996, 2001) in the C.J. Strike–Swan Falls reach have provided valuable demographic information on this sturgeon population. Of particular importance is that survey results have shown continued low abundance of small sturgeon (less than 92 cm) in the population over the last decade (see section 4.5.2.). As a result, measures have been proposed to improve recruitment to the C.J. Strike–Swan Falls reach population by enhancing population productivity upstream in the Bliss–C.J. Strike reach. Population assessments would be important in decisions whether implemented measures were effective or alternative mitigation measures were warranted. Incorporating monitoring results into the population viability model would assist in tracking population demographics and refine risk/benefit predictions of potential alternative mitigation measures. Population assessments would also benefit resource management agencies and help them develop future policies for Snake River white sturgeon.

Population assessments should be conducted at intervals commensurate with detecting population responses from mitigation measures. In the case of the C.J. Strike–Swan Falls reach, a population assessment would be conducted following the completion of translocation efforts for Phase 2 (section 8.5.1.). Future monitoring intervals would probably depend on these survey results and whether alternative mitigation measures were warranted. For planning purposes, however, population assessments would be conducted at ten-year intervals for the duration of the license. Population assessments for the C.J. Strike–Swan Falls reach should also be closely coordinated with population monitoring in the Bliss–C.J. Strike reach to assist evaluation of mitigation measures that provide complementary benefits for these adjacent populations.

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8.5.4.2. Objective Monitor population status of white sturgeon in the C.J. Strike–Swan Falls reach of the Snake River.

8.5.4.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.5.4.4. Implementation Schedule A population assessment would be conducted within ten years following the initiation of Phase 2 translocation (section 8.5.1.). Future monitoring intervals would depend on these survey results and whether alternative mitigation measures were implemented at that time. However, for planning purposes, population assessments would be conducted at ten-year intervals for the duration of a new license for the C.J. Strike Project.

8.5.4.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals over the course of a new 30-year license for the C.J. Strike Project is estimated at $477,000.

8.5.5. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.5.6. Evaluate Effects of Angling below C.J. Strike Dam

8.5.6.1. Justification Angling is one of the most severe forms of exhaustive exercise that a fish can experience (Booth et al. 1995). Several studies on different species of fish have shown that exhaustive exercise, including angling, results in a variety of severe physiological disturbances including altered reproductive performance and delayed mortality (Nelson 1998, Lambert and Dutil 2000, Schreer et al. 2001). Since 1970, regulations for catch-and-release angling of white sturgeon have been enforced throughout the Snake River and promoted as a method to conserve white sturgeon stocks. However, little is known about the effects of repeated catch-and-release angling on white sturgeon.

The tailrace area below C.J. Strike Dam is very popular among sturgeon anglers. Angler catch records below C.J. Strike Dam have shown that 3,675 angler days were spent during 1994 to catch 1,550 sturgeon, making this area the most intensively fished reach for sturgeon in Idaho (IDFG 1995). During June 2001, two sturgeon carcasses that were probably a result of angling mortality were recovered in the tailrace of C.J. Strike Dam. Autopsies showed that these fish had ingested and retained a number of fishing hooks (ranging from 3 to 20), which had punctured the esophagus and intestinal tracts. Information on the stress placed on sturgeon during angling activities and the subsequent recovery time is needed. Knowing the physiological costs that are

76 Idaho Power Company Snake River White Sturgeon Conservation Plan incurred as a result of angling and how they may affect the survival of white sturgeon would be helpful to fishery managers. With such information, fishery managers would be able to make more informed decisions regarding the use of catch-and-release angling as a management tool for sustaining or recovering white sturgeon populations. IPC’s study to evaluate effects of angling below C.J. Strike Dam would be conducted in cooperation with the IDFG.

8.5.6.2. Objective Specific objectives for this measure would be developed by the IDFG.

8.5.6.3. Description A detailed description of this study would be developed by the IDFG. IPC would provide project support by supplying use of radio telemetry receivers, aerial antennas, and radio transmitters necessary to complete the field portion of the study below C.J. Strike Dam.

8.5.6.4. Implementation Schedule To be determined by the IDFG.

8.5.6.5. Cost Estimate A total of $20,000 would be allocated for project support.

8.5.7. Improve Water Quality in C.J. Strike Reservoir by Developing Specific Measures through the C.J. Strike TMDL

See section 8.4.4. for a description of water quality and proposed measures for the C.J. Strike project.

8.5.8. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 65.

8.6. Swan Falls–Brownlee Reach

8.6.1. Assess Water Quality-Related Impacts on Early Life Stages

8.6.1.1. Justification Comparison of population assessments (Reid et al. 1973, Reid and Mabbot 1987, Lepla et al. 2001) has shown that sturgeon abundance between Swan Falls and Brownlee dams has changed little since the 1970s and that the population still consists primarily of subadult and adult fish (see section 4.6.2.). Despite the presence of suitable hydrology and physical habitats expected to support population maintenance and growth (Chandler and Lepla 1997), sturgeon recruitment in

77 Snake River White Sturgeon Conservation Plan Idaho Power Company

this reach of the Snake River has been largely unsuccessful (Lepla et al. 2001). Results of a PVA model of factors controlling white sturgeon recruitment in the Snake River indicated that water quality was the primary factor limiting sturgeon between Swan Falls and Brownlee dams and that restoring recruitment would be unattainable unless water quality conditions were improved (Jager et al. 2001b).

Degraded water quality in the lower section of this reach (Brownlee Reservoir) has historically impacted white sturgeon. During July 1990, at least 28 adult white sturgeon were killed near the upper end of the reservoir (transition zone) as a result of lethal DO conditions of less than 1 mg/l (IDFG 1990). High summer temperatures combined with high nutrient loading have been identified as contributors to the lethal conditions. Brownlee Reservoir’s in-reservoir processing of these nutrient influxes—coming from agricultural activity and municipal wastes flowing in from the surrounding watersheds—typically culminates in severely degraded water quality during dry and normal hydrologic years. Only in wet years are summer inflows high enough to prevent large amounts of algae from accumulating and producing anoxic conditions in the reservoir (Myers et al. 2001). IPC has proposed to improve DO levels in Brownlee Reservoir as part of its relicensing efforts for the HCC.

Improvements to water quality in the riverine section between Swan Falls Dam and Brownlee Reservoir are also currently being developed through the middle Snake River–Succor Creek and Snake River–Hells Canyon TMDL processes. Pollutants identified in the 303 (d) listing of the river segment between Swan Falls Dam and Brownlee Reservoir include bacteria, pesticides, nutrients, nuisance algae, mercury, sediment, temperature, and DO. However, given the basin size and complexity of issues encompassed by these TMDLs (varying hydrology, pollutant processing, transport characteristics, anthropogenic influences, and others), the extent of and time frame for water quality improvement are uncertain. Additionally, the effects that degraded water quality have had on white sturgeon recruitment in the riverine section of this reach are still poorly understood. Further investigation regarding degraded water quality in riverine habitats associated with early life stage development should be conducted to determine whether contaminants and water temperature are contributing to poor recruitment. For instance, studies conducted in the Kootenai River have shown very high mortality of incubating white sturgeon eggs that have been coated with suspended solids and then incubated in unfiltered water from the Kootenai River. Organic matter and contaminants from suspended solids and river water were likely the primary sources of bacteria and fungi and contributed to low survival of the embryos (Kruse 2000). The Swan Falls–Brownlee reach receives very high organic loading from the surrounding watersheds (Harrison et al. 1999, Myers et al. 2001). This additional burden may be affecting the survival of incubating sturgeon eggs. Additionally, the bioaccumulation of contaminants in adult sturgeon may be passed through the eggs or sperm and affect the embryos, although the overall effect of these pollutants on sturgeon reproduction and survival is largely unknown.

Identifying the impact that degraded water quality has on early life stage survival may lead us to a clearer understanding of the mechanisms influencing recruitment within this sturgeon population. Such information would be useful for determining appropriate measures to restore white sturgeon in the Swan Falls–Brownlee reach. For instance, if study results show that water quality is not limiting early life stage survival, then translocation efforts (section 8.6.3.) to increase sturgeon productivity may be a desirable option. However, if early life survival cannot

78 Idaho Power Company Snake River White Sturgeon Conservation Plan be supported under existing water quality conditions, then hatchery supplementation (section 8.6.4.) using conservation aquaculture practices may be an interim measure to increase population abundance until habitats are restored.

8.6.1.2. Objective Assess potential effects of water quality on early life stage survival of white sturgeon in the Swan Falls–Brownlee reach.

8.6.1.3. Description The impacts of degraded water quality in the Swan Falls–Brownlee reach would be evaluated for the egg, larval, and YOY life stages of white sturgeon. Evaluations on egg survival would focus primarily on contaminant exposure associated with riverine habitats during spawning and incubation. This task could be accomplished by comparing contaminant uptake and survival rates for incubating eggs between natural in-river conditions and controlled laboratory environments. A combination of field and laboratory treatment groups would be used to determine contaminant uptake of embryos when they are exposed to riverbottom sediments, suspended solids (organics), and river water. Field treatment groups would be de-adhesed with riverbottom sediments associated with spawning areas below Swan Falls Dam and reared on-site with filtered and unfiltered river water. Laboratory treatment groups would be de-adhesed with clean, neutral media and reared on filtered water for control comparisons. Bioassays of treatment groups would also be conducted to determine the bioaccumulated contaminant concentrations (metals, organochlorine pesticides, and PCBs) resulting from parental contribution, riverbottom de- adhesion media, and suspended solids in river water.

The effect of water quality on larval and YOY survival would focus primarily on water temperature. Peak summer temperatures in the lower river above Brownlee Reservoir were as high as 28.8 °C during 2002, a level that may prove lethal for early life stages of white sturgeon. Laboratory trials would be conducted to determine mortality rates associated with increasing water temperatures. Temperature tolerances of larval and age-0 sturgeon would be compared with temperature regimes occurring in the Swan Falls–Brownlee reach to determine whether existing conditions were limiting survival and recruitment for early life stages of white sturgeon.

White sturgeon eggs, larvae, and age-0 sturgeon needed for laboratory and field experiments could be obtained by spawning a reproductive female and male sturgeon from the Swan Falls– Brownlee reach. The laboratory work could be performed at the College of Southern Idaho or at another suitable research facility with the necessary equipment to maintain desired water temperatures and the sturgeon culture expertise to spawn, incubate, and rear white sturgeon.

8.6.1.4. Implementation This measure would be implemented within one year after a new license were issued for the HCC. We anticipate that two years would be required to complete field and laboratory evaluations.

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8.6.1.5. Cost Estimate Conducting a two-year study on assessing the potential effects of water quality on early life stage survival of white sturgeon in the Swan Falls–Brownlee reach is estimated to cost $326,000.

8.6.2. Improve Dissolved Oxygen Conditions in Brownlee Reservoir

Currently, DO levels in Brownlee Reservoir do not always meet the Idaho or Oregon water quality standards (Myers et al. 2001), nor are they adequate to support all designated beneficial uses (IDEQ and ODEQ 2001). DO in Brownlee Reservoir can become severely degraded, especially during summer, a condition that occasionally causes fish mortality. To mitigate for project-related impacts to water quality, IPC has proposed aeration in Brownlee Reservoir as part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971). Both the ODEQ and IDEQ have determined through their analyses in the draft Snake River–Hells Canyon TMDL process that reductions in inflowing nutrient and organic matter, along with IPC’s proposed level of aeration, should result in compliance with DO standards for Brownlee Reservoir (IDEQ and ODEQ 2001). IPC has proposed to develop specific design features, operation details, an implementation schedule, and effectiveness monitoring within the context of the § 401 water quality certification process.

However, while white sturgeon in Brownlee Reservoir may benefit from proposed measures regarding water quality, actions that are part of the draft Snake River–Hells Canyon TMDL and § 401 water quality certification processes for the HCC are considered outside the immediate scope of the WSCP. Therefore, measures and costs associated with water quality improvements as identified within the TMDL and § 401 water quality certification processes are not included in the WSCP.

8.6.3. Translocate Reproductive-Sized White Sturgeon to Increase Spawner Abundance and Population Productivity

8.6.3.1. Justification Based on the 1996–1997 population assessment for the Swan Falls–Brownlee reach, the white sturgeon population within this segment of the Snake River is low in abundance and displays little evidence of recruitment (Lepla et al. 2001). Catch rates and overall numbers of sturgeon sampled (n = 42) in this reach were very low, with most fish captured near the upper end of the reach between Swan Falls and Walters Ferry. Recruitment levels appear to have remained poor since earlier IDFG surveys (Reid et al. 1973, Reid and Mabbot 1987): the population consisted primarily of subadult and adult sturgeon, and few fish were less than 92 cm TL (see section 4.6.2.). The continuing presence of some small sturgeon indicates that recruitment is occurring at very low levels. The estimated number of annual female spawners in the population was also low (n = 7, Lepla et al. 2001), suggesting that future recruitment levels will probably remain low. These levels may be below those necessary to sustain this population without intervention. Reproductive-sized sturgeon could be translocated as a potential tool for improving white sturgeon productivity between Swan Falls and Brownlee dams. Adult translocation would increase the number of mature fish within the population, thereby increasing opportunities for

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natural production. However, the feasibility of this measure would first depend on improving water quality within this reach.

As discussed in sections 3.3. and 8.6.1., severe water quality degradation, particularly in the lower river and Brownlee Reservoir, appears to be limiting white sturgeon in this reach. PVA model simulations have indicated that water quality is the primary factor limiting white sturgeon recruitment in the Swan Falls–Brownlee reach (Jager et al. 2001b). Specifically, DO levels in the transition zone of Brownlee Reservoir should be improved before translocation efforts are undertaken. IPC has proposed to improve DO levels in Brownlee Reservoir by using aeration (section 8.6.2.).

Implementation of translocation efforts would also depend on study results from section 8.6.1. This measure evaluates whether degraded water quality conditions associated with riverine habitats are limiting early life stage survival of white sturgeon. If study results show that water quality conditions are not limiting early life stage survival and that natural production can be supported under existing conditions, then translocation of reproductive-sized sturgeon to the Swan Falls–Brownlee reach could be used as a method to increase spawn numbers and restore sturgeon productivity. Similar actions, such as trawl-and-haul supplementation, have been used to improve white sturgeon productivity in the impounded reaches of the lower Columbia River (Kern et al. 2001).

As indicated, the feasibility of this measure would first depend on improved water quality conditions. Determining a suitable source, or donor, population(s) for translocation to the Swan Falls–Brownlee reach would be decided pending results from reservoir aeration (section 8.6.2.) and the assessment of water on the early life stage survival of white sturgeon (section 8.6.1.). A PVA risk analysis of genetic and demographic costs incurred by the source and recipient populations would be evaluated prior to implementation. In addition, as water quality studies were undertaken in the Swan Falls–Brownlee reach, translocation evaluations regarding spawning performance of transported adult sturgeon would also be conducted upstream in the Bliss–C.J. Strike reach (section 8.5.1.). This information, along with results from water quality assessments and PVA model evaluations of suitable source population(s), would be used to evaluate the feasibility of translocation efforts in the Swan Falls–Brownlee reach.

8.6.3.2. Objective Translocate reproductive-sized white sturgeon into the Swan Falls–Brownlee reach to increase spawner abundance and improve population productivity.

8.6.3.3. Description Reproductive-sized sturgeon would be translocated to the Swan Falls–Brownlee reach on an experimental basis. Such efforts would involve a two-phased approach similar to the approach described for translocation in the C.J. Strike–Swan Falls reach (section 8.5.1.). During Phase 1, we would begin translocating reproductive sturgeon to evaluate spawning success of transplanted spawners. Radio telemetry would be used to monitor spawning behavior and identify key spawning locations. After spawning were complete, we would attempt to recapture telemetered spawners to surgically confirm whether these selected individuals had spawned. Pending

81 Snake River White Sturgeon Conservation Plan Idaho Power Company successful spawning, Phase 2 efforts would begin translocating reproductive-size sturgeon to increase spawner abundance and population productivity. A population assessment would be conducted following Phase 2 translocation to evaluate recruitment success.

8.6.3.4. Implementation Schedule Translocation of white sturgeon to the Swan Falls–Brownlee reach efforts could be implemented within one year after a new license were issued for the HCC. However, feasibility of translocation would also depend on improved DO conditions in the transition zone of Brownlee Reservoir (section 8.6.2.) and study results from the assessment of water quality on early life stage survival of white sturgeon (section 8.6.1.). For planning purposes, if study results indicated that water quality would not be limiting, Phase 1 efforts would operate on an experimental basis for two to four years to determine whether transported adults spawn in the Swan Falls–Brownlee reach. If spawning were confirmed, translocation efforts would continue on an annual basis (Phase 2) for a period of ten years. After that time, the feasibility of translocation to enhance population productivity and recruitment would be reviewed based on a population assessment. If study results indicated feasibility, the translocation efforts would continue on an annual basis for the duration of the new license for the HCC or until target goals were met. Periodic reviews of the translocation program would be based on future population assessments.

8.6.3.5. Cost Estimate The cost of conducting a translocation program for the duration of a new 30-year license for the HCC is estimated at $552,000.

8.6.4. Develop Experimental Conservation Aquaculture Plan

8.6.4.1. Justification Detailed justification and description of conservation aquaculture are discussed in section 8.1.2. The decision to develop a conservation aquaculture program for the Swan Falls–Brownlee reach would largely depend on results from the assessment on early life stage survival (section 8.6.1.) and the management directives by the IDFG and ODFW. For instance, if study results from section 8.6.1 show that natural production cannot be supported under existing water quality conditions and improving conditions appears unlikely, then opportunities to develop a conservation aquaculture program for the Swan Falls–Brownlee reach may be investigated with the IDFG and ODFW. Hatchery supplementation could be used as a potential tool to bypass current recruitment bottlenecks and replace failed natural recruitment as an interim measure to maintain adequate population size and genetic variability until water quality conditions become adequate to support natural recruitment.

8.6.4.2. Objective Maintain adequate population size and genetic variability of white sturgeon in the Swan Falls– Brownlee reach using conservation aquaculture.

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8.6.4.3. Description A conservation aquaculture program should contain measures that minimize both genetic risks to existing wild sturgeon populations in the Snake River and demographic risks of removing broodstock on the productivity of source populations. Careful design incorporating broodstock collection, mating protocols, and release numbers should be considered to balance family groups and avoid genetic swamping (see section 8.1.2.3.). Protocols should also include actions that minimize the risk of inbreeding and reduce the potential for selecting maladaptive traits in the released sturgeon. Protocols should also be established requiring selective marking of the hatchery fish with PIT tags and/or removal of various scute patterns to differentiate release groups and assist with future evaluations of survival rates, condition factor, growth rates, and movement behavior. These follow-up population assessments (section 8.6.5.) would be required to determine whether the hatchery program provided the intended benefits and information for adaptive management as the program developed. The plan should also incorporate rigorous protocols for fish health to limit disease risks in hatchery and wild fish. Existing facilities and sturgeon culture expertise at the College of Southern Idaho in Twin Falls could be suitable resources for spawning and rearing hatchery-produced white sturgeon.

8.6.4.4. Implementation Schedule Following the issuance of a new license for the HCC, the decision to develop a conservation aquaculture program would depend on study results from the assessment of water quality on early life stage survival (section 8.6.1.) and management directives by the IDFG and ODFW. For planning purposes, a conservation aquaculture program would be conducted on an experimental basis for a period of ten years to increase population abundance. Within six years of initiating the program, a population assessment (section 8.6.5.) would be conducted to evaluate survival/growth rates of stocked fish and determine whether conservation aquaculture had provided intended benefits and should be continued or whether alternative mitigation measures were warranted.

8.6.4.5. Cost Estimate The costs associated with this measure would depend on the level of production and duration of the program required to meet program goals. For cost estimation at this time, we considered two people sampling for up to three months (February to April) a reasonable effort to capture broodstock consisting of at least one female and two or more male sturgeon. We also assumed two family groups of 500 fish per family to calculate the facility costs (feed, labor, PIT tags, and others) associated with spawning and rearing of progeny for one year prior to stocking. Based on these assumptions, the annual cost associated with broodstock collection and rearing of progeny for one year is estimated at $84,000. For planning purposes, the cost to support an experimental conservation aquaculture program over a ten-year period in the Swan Falls–Brownlee reach is estimated at $840,000.

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8.6.5. Conduct Periodic Population Assessments

8.6.5.1. Justification Past population assessments (Reid et al. 1973, Reid and Mabbot 1987, Lepla et al. 2001) between Swan Falls and Brownlee dams have shown that white sturgeon abundance is low and recruitment levels have remained poor. As efforts to increase sturgeon abundance (either through natural or artificial means) are undertaken, periodic population assessments would be necessary to monitor population changes and determine the effectiveness of the implemented measures. For instance, if white sturgeon were translocated (section 8.6.3.), a comprehensive population assessment would be conducted following the completion of Phase 2 to determine whether translocation had provided the intended benefits. These assessments would allow the approach to remain adaptive and provide the means to determine whether alternative mitigation measures were warranted. However, a more intensive monitoring program may be associated with a conservation aquaculture program (section 8.6.4.) to evaluate whether use of hatchery fish is helping us meet program goals. For example, stocking numbers may need to be adjusted depending on survival and growth rates. Monitoring results can be incorporated into the PVA to evaluate expected population demographics, assist with decision points, and refine risk/benefit predictions of alternative measures. These population assessments would probably provide valuable feedback to resource agencies and help them determine future management policies for Snake River white sturgeon populations.

8.6.5.2. Objective Monitor population status of white sturgeon in the Swan Falls–Brownlee reach of the Snake River.

8.6.5.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.6.5.4. Implementation Schedule Population assessments would be conducted at time frames based on monitoring and evaluation needs of translocation (section 8.6.3.) and/or conservation aquaculture (section 8.6.4.). That is, a comprehensive population assessment would be conducted within ten years after Phase 2 translocation were initiated and/or within five to seven years after a conservation aquaculture program were initiated. Future population assessment intervals would probably depend on the survey results, although for planning purposes, we anticipate that population assessments would be conducted at ten-year intervals for the duration of a new license for the HCC.

8.6.5.5. Cost Estimate The cost of conducting three population assessments in the Swan Falls–Brownlee Reach over the course of a new 30-year license for the HCC is estimated at $797,000.

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8.6.6. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.6.7. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 65.

8.7. Brownlee–Hells Canyon Reach (Oxbow and Hells Canyon Reservoirs)

8.7.1. Improve Dissolved Oxygen and Total Dissolved Gas Conditions in Oxbow and Hells Canyon Reservoirs

Oxbow and Hells Canyon reservoirs seasonally experience conditions that lead to low DO levels in water released from the dams. These low DO conditions create habitat conditions that are less than optimal for fish species in Oxbow and Hells Canyon reservoirs, as well as in a short section of the Snake River downstream of Hells Canyon Dam (Chandler 2001). Although implementation of the Snake River–Hells Canyon TMDL should significantly improve DO levels in reservoirs associated with the HCC, it is difficult to quantify the improvements that may result from those measures. Because of this uncertainty, IPC has also proposed oxygen supplementation at Brownlee Dam, in addition to TMDL implementation measures, as a potential means for improving DO levels in Oxbow and Hells Canyon reservoirs as part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971). At this time, IPC has identified turbine venting as the most likely method for oxygen supplementation. IPC has proposed that specific details regarding design and operation, as well as an effectiveness- monitoring plan, for turbine venting (or other supplementation method) be developed through consultation with ODEQ and IDEQ within the context for the § 401 water quality certification process. The effects from TDG are not an annual event and efforts are taken by IPC to abate spill whenever possible. IPC will continue to take operational measures to minimize elevated TDG below Brownlee and Oxbow dams

Although white sturgeon populations may benefit from these proposed measures, actions that are part of the Snake River–Hells Canyon TMDL and § 401 water quality certification processes for the HCC are considered outside the immediate scope of the WSCP. Therefore, measures and costs associated with water quality improvements are not included in the WSCP.

8.7.2. Conduct Periodic Population Assessments

8.7.2.1. Justification White sturgeon continue to persist in Oxbow and Hells Canyon reservoirs, though numbers are likely very low compared to what once existed there. Assessments conducted by the IDFG, ODFW, and IPC found only a few wild sturgeon remaining within these segments (see sections

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4.7.2. and 4.8.2.). Low numbers (n = 263) of hatchery-propagated juvenile sturgeon have been released into Oxbow and Hells Canyon reservoirs by the IDFG and Nez Perce Tribe. Periodic population assessments would be conducted in Oxbow and Hells Canyon reservoirs to monitor the status of existing wild and hatchery sturgeon. Assessments would also allow hatchery fish to be evaluated for their maturation, growth, and survival rates.

8.7.2.2. Objective Monitor population status of white sturgeon within Oxbow and Hells Canyon reservoirs.

8.7.2.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.7.2.4. Implementation Schedule Within one year after a new license were issued for the HCC, population assessments would be conducted in Oxbow and Hells Canyon reservoirs at ten-year intervals for the duration of the new project license.

8.7.2.5. Cost Estimate The cost associated with conducting three population assessments at 10-year intervals for the duration a new 30-year license for the HCC is estimated at $163,000 for Oxbow Reservoir and $205,000 for Hells Canyon Reservoir.

8.7.3. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.7.4. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 65.

8.8. Hells Canyon–Lower Granite Reach

8.8.1. Improve Dissolved Oxygen and Total Dissolved Gas Conditions below Hells Canyon Dam

Water quality below Hells Canyon Dam does not meet Idaho or Oregon state standards for DO and TDG during brief periods of most years. For instance, DO levels measured in the tailrace of Hells Canyon Dam can drop to as low as 2.8 mg/l for several weeks during late summer. Spilling water in excess of approximately 2,500 cfs at Hells Canyon Dam can also increase TDG to supersaturation levels that exceed the 110% protective standard (Myers and Parkinson 2002). As part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971),

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IPC has proposed to implement its portion of the DO allocation identified in the draft Snake River–Hells Canyon TMDL and also to install and operate turbine-venting, or an equivalent oxygen supplementation system, at Brownlee Dam as a means to improve DO levels in Oxbow and Hells Canyon reservoirs and the tailwaters of Hells Canyon Dam. IPC has also proposed installing flow deflectors at Hells Canyon Dam to reduce TDG levels during periods of spill. IPC has proposed to develop specific design features, operation details, an implementation schedule, and effectiveness monitoring for these measures within the context of the § 401 water quality certification process.

While white sturgeon below Hells Canyon Dam may benefit from these proposed measures, actions that are part of the draft Snake River–Hells Canyon TMDL and § 401 water quality certification processes for the HCC are considered outside the immediate scope of the WSCP. Therefore, measures and costs associated with water quality improvements are not included in the WSCP.

8.8.2. Conduct Periodic Population Assessments

8.8.2.1. Justification The Hells Canyon–Lower Granite reach of the Snake River supports the largest viable population of white sturgeon in Idaho. Population assessments between 1970 and 2001 showed positive trends in recruitment, indicating successful reproduction and growth of this population. Juvenile sturgeon less than 92 cm TL continue to dominate the population, and size groups greater than 92 cm TL have steadily increased since the 1970s. Survival estimates are similar to those observed in several other Snake River populations, and mean relative weight of the population has not declined over the course of 30 years. The current sturgeon population below Hells Canyon Dam is genetically diverse and exhibits a healthy population structure based on a stock structure dominated by juveniles with a wide range of size classes and stages of maturity from immature juveniles to reproductive adults.

Through periodic population assessments in the Hells Canyon–Lower Granite reach, IPC would monitor temporal population trends and evaluate the effectiveness of proposed measures, such as those designed to improve water quality. These assessments would also allow us to identify unforeseen risks before viability and persistence were threatened. Given that this reach represents the second stronghold reach for Snake River white sturgeon, PM&E measures associated with this and adjacent reaches must not threaten the viability and persistence of this population. For example, if future translocation actions used the Hells Canyon–Lower Granite sturgeon population as a donor source for rebuilding upstream populations, the benefits and risks of translocation on donor/source population demographics and genetic implications would be evaluated using the PVA model. Population monitoring would also be conducted at ten-year intervals and provide valuable feedback to resource agencies to help them determine future management directives for Snake River white sturgeon populations.

8.8.2.2. Objective Monitor population status of white sturgeon in the Hells Canyon–Lower Granite reach of the Snake River.

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8.8.2.3. Description Population assessments would be conducted using methods described in section 8.1.3.3.

8.8.2.4. Implementation Schedule Within one year after a new license were issued for the HCC, population assessments would be conducted between Hells Canyon and Lower Granite dams at approximately ten-year intervals for the duration of the new license.

8.8.2.5. Cost Estimate The cost of conducting three population assessments at 10-year intervals for the duration of a new 30-year license for the HCC is estimated at $1,300,000.

8.8.3. Monitor Genotypic Frequencies

See section 8.1.4. for a description of this proposal.

8.8.4. Develop Schematic Diagram of Proposed Mitigation Measures

See Figure 65.

9. EXPLANATION FOR REJECTION OF ANY WSTAC RECOMMENDATIONS BY IPC

IPC has not proposed all of the measures recommended by the WSTAC (see section 7). This section includes measures that were recommended but that IPC chose not to propose. Explanations for IPC’s rejection of these recommended measures are provided below. WSTAC review/comment to the draft Snake River White Sturgeon Conservation Plan and IPC response to comments are also provided in Appendix 3.

9.1. Shoshone Falls–Upper Salmon Falls Reach

• Determine and obtain minimum flows needed for white sturgeon spawning, incubation, and early rearing life stages.

IPC cannot “obtain” water for minimum flows in the middle Snake River. Idaho law governs the acquisition and maintenance of instream flows for fish and wildlife habitat purposes. While Idaho law recognizes that minimum stream flows for the protection of fish and wildlife habitat and aquatic life are a beneficial use of water, it does not allow private appropriators, such as IPC, to acquire water rights for such instream uses. Only the Idaho Water Resource Board (IWRB) may file an application to appropriate water for the purposes of a minimum stream flow. Such applications are filed with the Idaho Department of Water Resources (IDWR) and may be

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approved by the director, after notice and hearing, only if the requested minimum stream flow meets the following criteria:

a) Will not interfere with any other water right with an earlier priority date

b) Is in the public, as opposed to private, interest

c) Is necessary for the preservation of fish and wildlife habitat, aquatic life, recreation, aesthetic beauty, navigation, transportation, or water quality of the stream

d) Is the minimum flow level and not the ideal or most desirable level

e) Is capable of being maintained as evidenced by records of stream flows

I.C. § 42-1503. Approved applications for minimum stream flow purposes must also be submitted to and approved by the Idaho legislature. Id. This statutory provision clearly assumes that there must be unappropriated water available to fulfill or maintain the minimum flow established. The Snake River above Milner Dam is overappropriated, and the IWRB has recognized that, at times, the exercise of water rights above Milner Dam may reduce flows past the dam to zero12. This situation makes the establishment of a minimum flow in the Snake River below Milner Dam in excess of the historical natural flows improbable, if not impossible.

Other than natural (or flood) flows that pass Milner Dam, the primary source of available water available upstream of Milner Dam is storage water. The bulk of this water, in excess of 4.1 MAF, is stored in seven federally authorized storage projects. The majority of this upstream storage is dedicated to irrigation use. Water District 01, under the authority of the IWRB, does operate a rental pool, or water bank, in the upper Snake River, which is under specific rules and procedures. Those rental pool rules provide a preference to agricultural leases, giving agricultural users a first opportunity to lease storage water before any other proposed uses. This preference severely limits the amount of water available to other uses, particularly during low-water years. Moreover, those rules provide that rental pool water may only be leased for a beneficial use recognized by state law and may not be used to maintain minimum flows greater than those established pursuant to state law (see R.1.2.C. and 1.3., Water District 01 Rental Pool Procedures). The rules also limit the ability of a downstream applicant to lease water for instream purposes, requiring that an applicant possess a valid water right for the proposed instream use of the water. If an applicant does hold a water right for an instream use (note that, under Idaho law, only the IWRB can hold such a water right), rental pool water cannot be used to establish flows greater than the minimum flows established pursuant to state law.

• Translocate reproductive-sized adults to increase number of spawners in the population and improve white sturgeon productivity.

12 Idaho Water Resource Board. Idaho State Water Plan (1996), Policy 5B. Comprehensive State Water Plan, Snake River: Milner Dam to King Hill (1993). U.S. Bureau of Reclamation, Description of Bureau of Reclamation System Operations Above Milner Dam, January 1996 (Revised December 1997).

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IPC does not propose translocation of reproductive-sized adults to increase spawner abundance in the Shoshone Falls–Upper Salmon Falls reach at this time. Although having too few adult spawners in the population may have contributed to poor past recruitment trends (Lukens 1981), results from the latest population assessment in 2001 (Lepla et al. 2002) suggest that spawner limitations may soon be alleviated as hatchery sturgeon approach maturity. Since 1989, at total of 1,208 hatchery sturgeon were stocked in the Shoshone Falls–Upper Salmon Falls reach. In 2001, Lepla et al. estimated the population at 777 fish and found some hatchery females approaching first maturity while several males were already displaying reproductive readiness. Based on the current population structure, increasing numbers of hatchery fish will likely mature within the next five years, given that the majority of individuals in the population range between 10 and 15 years of age. Therefore, translocating additional reproductive-size adults to this reach does not appear warranted at this time. Given the expected increase in spawner abundance, there should be sufficient spawners in the population to begin evaluating spawning and recruitment success, as proposed in section 8.1.1. In fact, it may be prudent to first determine whether habitat conditions in this reach can support natural production before removing adult sturgeon from other reaches of the Snake River. Translocation would be reconsidered if future evaluations indicated that additional spawners would benefit population restoration efforts in the Shoshone Falls–Upper Salmon Falls reach.

9.2. Upper Salmon Falls–Lower Salmon Falls Reach

• Determine feasibility of passage in the North Channel below Upper Salmon Falls Dam.

IPC has evaluated a full range of sturgeon passage alternatives as well as the constraints associated with passing white sturgeon upstream and downstream of the HCC (Wittmann-Todd et al. 2001). Passage options were based on studies from Russian and Columbia River sturgeon- passage facilities. Wittmann-Todd et al. (2001) concluded that the most feasible and practical alternative was capture and transport (i.e., translocation). The capture-and-transport alternative can be accomplished with existing technology and represents the most reliable solution for passing sturgeon at this time. All other options explored (including fish ladders, locks, lifts, pressured passage systems, trap and transport, surface collections, spillway releases, behavior guidance structures, and turbine exclusion) have biological uncertainties, particularly those options relying on volitional responses. Sturgeon behavior does not necessarily favor voluntary upstream passage via facilities that have been effective for other species (Cooke et al. 2002). The engineering challenges, modifications to existing project features, and cost estimates for many of the potential options evaluated were also very high. While the engineering challenges and costs for passing sturgeon at Upper Salmon Falls Dam may differ from passage options reported for the HCC, the biological uncertainties associated with these various alternatives would not differ.

If future population assessments of the Upper Salmon–Lower Salmon Falls reach indicated that upstream passage for sturgeon would be beneficial, IPC would propose using translocation as an effective means for passing sturgeon upstream of Upper Salmon Falls Dam. This approach has been used successfully by ODFW for transporting white sturgeon among lower Columbia River reservoirs to mitigate for lost recruitment and upstream passage (Rien and North 2002).

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9.3. Lower Salmon Falls–Bliss Reach

• Develop experimental conservation aquaculture plan.

Although conservation aquaculture may be a potential tool for helping population restoration efforts, IPC does not support developing a conservation aquaculture plan for the Lower Salmon Falls–Bliss reach at this time. The contribution that historical stocking efforts have had toward increasing abundance and population productivity in the Lower Salmon Falls–Bliss reach remains largely unknown and should be evaluated before hatchery supplementation is considered. A total of 2,560 hatchery fish were stocked below Lower Salmon Falls Dam from 1989 to 1994, yet few hatchery fish were recaptured during the 1992–1993 population assessment (section 4.3.2.). Although low captures may have been related in part to sampling gear efficiencies, growth and survival rates of hatchery sturgeon observed in the Shoshone Falls– Upper Salmon Falls reach suggest that hatchery sturgeon below Lower Salmon Falls Dam should have recruited to the collection gear at numbers greater than what was sampled during the survey.

To address this uncertainty, IPC proposes conducting a population assessment to determine the current status of hatchery-stocked sturgeon below Lower Salmon Falls Dam (section 8.3.1.) before determining future actions. If sampling efforts reaffirm low abundance of hatchery sturgeon, as suspected from the 1992–1993 study results, then the long-term benefit of developing a conservation aquaculture program for this reach seems questionable. Based on current assumptions, restoration efforts may be constrained not only by limited habitats (due to the short length of reach) but also by downstream export of sturgeon. While periodic stocking may help offset the effects of export, implementing a hatchery-based program within this reach warrants careful consideration. The cost of hatchery supplementation in terms of lost reproduction to the donor population that would result from removing broodstock must also be weighed against the anticipated benefits of supplementing the Lower Salmon Falls–Bliss reach. Other factors, such as disease outbreaks or genetic implications that could potentially accrue from selective hatchery practices, could expose the adjacent Bliss–C.J. Strike sturgeon population to unnecessary risk. Although conservation aquaculture employs methods to minimize risk to wild stocks, such programs are still largely experimental and have yet to demonstrate their long-term effectiveness in preserving white sturgeon populations.

IPC has proposed conservation aquaculture as a potential tool for population restoration in the Shoshone Falls–Upper Salmon Falls and Swan Falls–Brownlee reaches. These two reaches appear more suited for experiments with hatchery supplementation because of their spatial separation from the Bliss–C.J. Strike and Hells Canyon–Lower Granite sturgeon populations. If evaluation of the historical stocking efforts below Lower Salmon Falls Dam (section 8.3.1.) indicates that they were successful, potential future measures for implementing hatchery supplementation in this reach would be reviewed with the WSTAC.

• Implement seasonal run-of-river project operations at Lower Salmon Falls Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TDB).

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An evaluation of the effects that project operations of the Lower Salmon Falls Dam have on environmental resources was presented in the final environmental impact statement (EIS) for the Shoshone Falls, Upper Salmon Falls, Lower Salmon Falls, and Bliss projects (FERC 2002a). Although constraints on load-following operations at Lower Salmon Falls Dam have the potential to benefit habitat for sturgeon (as defined by WUA), our data suggest that other reach limitations would likely prevent a positive population response. A common observation in short reaches within both the Mid-Snake projects (Upper Salmon Falls, Lower Salmon Falls, and Bliss) and HCC (Brownlee, Oxbow, and Hells Canyon) has been little or no detectable presence of sturgeon recruitment. A PVA of Snake River white sturgeon indicated that larval export was a primary factor limiting recruitment within this short segment of the Snake River (Jager et al. 2001a). In addition, the relatively short length of the reach between Lower Salmon Falls and Bliss dams offers limited rearing habitats for sturgeon. Population assessments indicate a low abundance of both naturally produced (Lukens 1981) and hatchery-stocked sturgeon in the Lower Salmon Falls–Bliss reach (Lepla and Chandler 1995b), a finding suggesting that suitable habitats for population growth and maintenance may be limited. These factors appear to be the major contributors to the current status of wild and hatchery sturgeon stocks below Lower Salmon Falls Dam.

The social and economic costs of operating under the seasonal ROR alternative were evaluated by FERC (FERC 2002a). Constraints on project operations at Lower Salmon Falls Dam result in operational restrictions at Bliss Dam because operations at Lower Salmon Falls Dam shape inflows to the Bliss Project. A seasonal ROR operation would reduce the current dependable capacity of the Lower Salmon Falls and Bliss projects from 70.5 and 77.6 MW to 20.5 and 36 MW, respectively. These reductions constitute more than a 60% loss of the dependable capacity of these two projects. The approximately 92 MW of lost dependable capacity in Idaho would need to be replaced, either by IPC or another entity. In addition, under the seasonal ROR alternative, IPC would have to develop new generation facilities to replace the lost generation and dependable capacity. Additional transmission facilities would likely also be required. Existing transmission bottlenecks already exist on sections of IPC’s transmission system. In addition to monetary costs, any new construction would incur environmental costs as well.

9.4. Bliss–C.J. Strike Reach

• Implement seasonal run-of-river project operation at Bliss Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TDB).

Evaluation of project operations showed that white sturgeon spawning, incubation, and larval habitats (as defined by WUA) would benefit from seasonal ROR operations at Bliss Dam (FERC 2002a). In addition, as discussed in section 4.4.2., the estimated age structure of the sturgeon population in 2000 indicated that little recruitment occurred in below-normal water years (1988, 1989, and 1990) when aggressive load following occurred during the spawning season, but that higher levels of recruitment occurred in years with similar hydrology (1992, 1993, and 1994) and reduced load following. However, IPC again concluded that the cost in terms of lost operational flexibility for meeting fluctuating power demands and the associated loss of dependable capacity at Bliss and Lower Salmon Falls dams exceeded the environmental benefits of the seasonal ROR alternative.

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• Improve water quality in C.J. Strike Reservoir: Study discharge options at C.J. Strike Dam to improve water quality.

IPC does not support studying discharge options at C.J. Strike Dam to improve water quality in C.J. Strike Reservoir. Water quality monitoring over an 11-year period has shown that the C.J. Strike Project has been 99.8% compliant with state water quality standards and that no additional measures beyond participation and implementation of appropriate TMDLs would be necessary (IPC 2000b,d). IDEQ has initiated the TMDL development process that includes the C.J. Strike Project area, and it is expected to be completed by 2004. IDEQ has issued a § 401 water quality certificate for the C.J. Strike Project and, as part of that certification, IPC is providing $50,000 annually for TMDL development and, after completion of the TMDL, will cooperate and implement measures to achieve IPC allocations. No water quality-related mortality of sturgeon has been documented in C.J. Strike Reservoir. Although poor water quality may at times (depending on hydrologic year) restrict use of the lower reservoir during summer for some sturgeon, it does not appear to be affecting fish condition based on high relative weight values and favorable growth rates observed within this population.

9.5. C.J. Strike–Swan Falls Reach

• Provide habitat conditions suitable for white sturgeon spawning: Determine feasibility for a trapping facility to collect spawners (all ages) below C.J. Strike Dam.

• Determine feasibility of passage at C.J. Strike Dam.

IPC has evaluated a full range of sturgeon passage alternatives, as well as the constraints associated with passing white sturgeon upstream and downstream of the HCC (Wittmann-Todd et al. 2001). Passage options were based on studies from Russian and Columbia River sturgeon- passage facilities. Wittmann-Todd et al. (2001) concluded that the most feasible and practical alternative was capture and transport (i.e., translocation). The capture-and-transport alternative can be accomplished with existing technology and represents the most reliable solution for passing sturgeon at this time. All other options explored (including fish ladders, locks, lifts, pressured passage systems, trap and transport, surface collections, spillway releases, behavior guidance structures, and turbine exclusion) have biological uncertainties, particularly those options relying on volitional responses. Sturgeon behavior does not necessarily favor voluntary upstream passage via facilities that have been effective for other species (Cooke et al. 2002). The engineering challenges, modifications to existing project features, and cost estimates for many of the potential options evaluated were also very high. Although the engineering challenges and costs for passing sturgeon at C.J. Strike Dam may differ from passage options reported for the HCC, the biological uncertainties associated with these various alternatives would not differ.

Given the biological uncertainty and presumably high cost of building a trapping facility to collect spawners at C.J. Strike Dam (which may not be used by sturgeon), IPC has proposed translocation of reproductive-sized adults (section 8.5.1.) as an effective means of passing sturgeon upstream of the C.J. Strike Project. A similar approach has been used successfully by

93 Snake River White Sturgeon Conservation Plan Idaho Power Company

ODFW for transporting white sturgeon among lower Columbia River reservoirs to mitigate for lost recruitment and upstream passage (Rien and North 2002).

• Implement seasonal run-of-river project operation at C.J. Strike Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TDB).

An evaluation of project operations on environmental resources was presented in the final EIS for C.J. Strike Dam (FERC 2002b). An instream flow study and time-series analysis of project operations showed that operations reduce white sturgeon spawning habitat primarily during low- and normal-flow years. However, the physical habitat does not appear to support sturgeon reproduction even during high-flow years. Despite the occurrence of five consecutive high-flow years from 1982 to 1986 and four consecutive high-flow years from 1996 to 1999, population assessments in 1989 (IDFG 1992), 1994–1996 (Lepla and Chandler 1997), and 2001 (IPC unpublished data) show that stock structure has not changed appreciably over the past decade.

Time-series plots of sturgeon spawning habitat from 1996 to 1999 showed that load-following operations at C.J. Strike Dam had little effect on sturgeon habitat during the spawning season in these years. These results and population trend data suggest that adequate spawning conditions are generally unavailable to sturgeon below C.J. Strike Dam. Thus, neither improved water years nor changes in project operations are expected to provide significant increases to recruitment. The continued low abundance of smaller sturgeon suggests that spawning is largely unsuccessful and that the population is likely supported via recruitment from the more abundant sturgeon population immediately upstream in the Bliss–C.J. Strike reach. The overall low-gradient nature of this reach and lack of turbulent runs also suggest that, historically, white sturgeon probably spawned in other areas of the Snake River. Because the C.J. Strike–Swan Falls reach does not provide these habitats, IPC has proposed translocating reproductive-sized adults (as described in section 8.5.1.) from below C.J. Strike Dam upstream to the Bliss–C.J. Strike reach. These translocations would provide adults access to habitats that support natural production, “recapture” lost reproductive potential, and reestablish upstream gene flow. As demonstrated in recapture data, some sturgeon in the Bliss–C.J. Strike reach have emigrated downstream into the C.J. Strike–Swan Falls reach. Therefore, enhancing recruitment to the Bliss–C.J. Strike reach would likely increase the number of sturgeon that move downstream to be recruited to the C.J. Strike–Swan Falls sturgeon population.

FERC has concluded that there would be little gain from a seasonal restriction on load following during the sturgeon spawning season because the physical habitats may be incapable of supporting sturgeon reproduction. FERC added that there would be little or no benefit to other resources from a seasonal load-following restriction. In addition, a seasonal ROR project operation would decrease overall power plant efficiency and operating flexibility, substitute less valuable off-peak energy for more valuable on-peak energy, and reduce the project’s dependable capacity. The lost of dependable capacity under seasonal ROR operations would need to be replaced, either by IPC or another entity. In addition, IPC would have lost the ability to generate power during periods of heavy demand. Depending on where the generation facilities would be built to replace the lost generation and dependable capacity, additional transmission facilities would likely also be required. Existing transmission bottlenecks already exist on sections of IPC’s transmission system. In addition to monetary costs, any new construction would result in environmental costs as well.

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• Improve water quality in C.J. Strike Reservoir: Study discharge options at C.J. Strike Dam to improve water quality.

See section 9.4. for IPC’s response.

9.6. Swan Falls–Brownlee Reach

• Increase flow.

IPC cannot obtain water for increasing flows in the middle Snake River. Idaho law governs the acquisition and maintenance of instream flows for fish and wildlife habitat purposes. While Idaho law recognizes that minimum stream flows for the protection of fish and wildlife habitat and aquatic life are a beneficial use of water, it does not allow private appropriators, such as IPC, to acquire water rights for such instream uses. Only the IWRB may file an application to appropriate water for the purposes of a minimum stream flow. Such applications are filed with the IDWR and may be approved by the director, after notice and hearing, only if the requested minimum stream flow meets the following criteria:

a) Will not interfere with any other water right with an earlier priority date

b) Is in the public, as opposed to private, interest

c) Is necessary for the preservation of fish and wildlife habitat, aquatic life, recreation, aesthetic beauty, navigation, transportation, or water quality of the stream;

d) Is the minimum flow level and not the ideal or most desirable level

e) Is capable of being maintained as evidenced by records of stream flows

I.C. § 42-1503. Approved applications for minimum stream flow purposes must also be submitted to and approved by the Idaho legislature. Id. This statutory provision clearly assumes that there must be unappropriated water available to fulfill or maintain the minimum flow established. The Snake River above Milner Dam is overappropriated, and the IWRB has recognized that, at times, the exercise of water rights above Milner Dam may reduce flows past the dam to zero13. This situation makes the establishment of a minimum flow in the Snake River below Milner Dam in excess of the historical natural flows improbable, if not impossible.

Other than natural (or flood) flows that pass Milner Dam, the primary source of available water available upstream of Milner Dam is storage water. The bulk of this water, in excess of 4.1 MAF, is stored in seven federally authorized storage projects. The majority of this upstream storage is dedicated to irrigation use. Water District 01, under the authority of the IWRB, does operate a rental

13 Idaho Water Resource Board. Idaho State Water Plan (1996), Policy 5B. Comprehensive State Water Plan, Snake River: Milner Dam to King Hill (1993). U.S. Bureau of Reclamation, Description of Bureau of Reclamation System Operations Above Milner Dam, January 1996 (Revised December 1997).

95 Snake River White Sturgeon Conservation Plan Idaho Power Company pool, or water bank, in the upper Snake River, which is under specific rules and procedures. Those rental pool rules provide a preference to agricultural leases, giving agricultural users a first opportunity to lease storage water before any other proposed uses. This preference severely limits the amount of water available to other uses, particularly during low-water years. Moreover, those rules provide that rental pool water may only be leased for a beneficial use recognized by state law and may not be used to maintain minimum flows greater than those established pursuant to state law (see R.1.2.C. and 1.3., Water District 01 Rental Pool Procedures). The rules also limit the ability of a downstream applicant to lease water for instream purposes, requiring that an applicant possess a valid water right for the proposed instream use of the water. If an applicant does hold a water right for an instream use (note that, under Idaho law, only the IWRB can hold such a water right), rental pool water cannot be used to establish flows greater than the minimum flows established pursuant to state law.

• Restore/protect riparian areas to hasten water quality improvements.

IPC does not believe that land acquisition and riparian habitat enhancement in tributaries will benefit white sturgeon enough to address the primary limiting factors. While they may provide measurable benefits to fish populations within those tributaries, the geographic scope required for changes to affect conditions facing white sturgeon in the mainstem Snake River is much larger and encompasses the entire Snake River basin upstream of the HCC. While IPC has proposed tributary enhancement measures and some land acquisition associated with the HCC license for other resources, IPC believes these alone will do little to enhance mainstem Snake River water quality conditions and that was not the intent in proposing them. IPC continues to believe that participation in the ongoing TMDL's associated with the mainstem Snake River will be the best way to contribute to the necessary habitat and water quality enhancements that will specifically benefit white sturgeon.

To mitigate for project-related impacts to water quality in Brownlee Reservoir, IPC has proposed reservoir aeration in its New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971). This proposed action, along with the implementation of TMDL load allocations assigned to other responsible parties, would improve oxygen conditions within the HCC so that they meet the appropriate Oregon and Idaho standards. Both ODEQ and IDEQ have determined through their analyses in the draft Snake River–Hells Canyon TMDL process that, through reductions in inflowing nutrient and organic matter and with IPC’s proposed level of aeration, DO standards for Brownlee Reservoir should be met (IDEQ and ODEQ 2001). IPC has also proposed that the specific details of reservoir aeration regarding design, location, and operation, as well as an effectiveness-monitoring plan, be developed through consultation with both ODEQ and IDEQ and within the framework of TMDL implementation and the § 401 water quality certification process for the HCC.

• Improve water temperature and total dissolved gas conditions in Brownlee Reservoir.

TDG levels that exceed the accepted state standard of 110% have not been documented in Brownlee Reservoir (Myers and Parkinson 2002). Elevated water temperatures occur both in Brownlee Reservoir and upstream in the free-flowing section of the Snake River. While these upper temperature levels may increase the risk for mortality of white sturgeon, elevated summer water temperatures associated with inflow are outside the control of IPC. IPC believes a

96 Idaho Power Company Snake River White Sturgeon Conservation Plan comprehensive watershed approach would be a more appropriate way to address the issue rather than arbitrarily and inequitably requiring IPC to improve conditions that are not the responsibility of IPC projects.

9.7. Brownlee–Hells Canyon Reach

• Transplant reproductive-sized adult white sturgeon to increase number of spawners and improve white sturgeon productivity.

IPC does not support translocation of reproductive-sized adults into Oxbow and Hells Canyon reservoirs as a method for increasing population productivity. The Snake River between Brownlee and Hells Canyon dams is composed almost entirely of reservoir habitats, except for a limited amount of free-flowing habitat near the upper end of the Oxbow Bypass and in the immediate vicinity of the powerhouse tailraces below Oxbow and Brownlee dams. Although these reservoirs may provide large suitable areas for juvenile and adult rearing, restoring and sustaining white sturgeon populations in Oxbow and Hells Canyon reservoirs based on natural production would be limited or maybe even impossible. The general inability of reservoir habitats to support adequate levels of natural production for population growth and maintenance has been observed in several other reservoirs in the Columbia River basin. White sturgeon populations that have low and annually variable recruitment include those in the lower Columbia River reservoirs while recruitment is virtually nonexistent in the middle and upper Columbia River reservoirs (Parsley et al. 1993, Beamesderfer et al. 1995, UCWSRI 2002). A PVA of factors controlling white sturgeon recruitment in Oxbow and Hells Canyon reservoirs indicated that water quality, spawner limitations, and larval export were also factors limiting simulated recruitment within these two reaches (Jager et al. 2001b).

Attempts to restore natural production in Oxbow and Hells Canyon reservoirs would require transplanting sufficient numbers of adults to increase spawner abundance. The most plausible donor population for translocation would be the Hells Canyon–Lower Granite sturgeon population because that reach supports a strong and genetically diverse population in the Snake River and lies adjacent to Oxbow and Hells Canyon reservoirs. However, this action would involve relocating adult sturgeon from a riverine reach with habitats that consistently support natural recruitment to reservoirs with limited potential for natural production. Because poor or failed sturgeon recruitment is common in other basin reservoirs, we suggest that outcomes may be similar in Oxbow and Hells Canyon reservoirs. The uncertainty of whether these two reservoirs can support natural production, coupled with the cost (lost reproduction to the donor population) of removing reproductive adults from a reach that supports natural production, makes this alternative undesirable.

• Develop a conservation aquaculture plan in cooperation with Idaho Department of Fish and Game, Nez Perce Tribe, and Oregon Department of Fish and Wildlife.

IPC does not support developing a conservation aquaculture plan for use in Oxbow and Hells Canyon reservoirs. The guiding principle of the WSCP suggests that measures not be implemented if they could put the health of stronghold populations at risk. The long-term consequences of hatchery supplementation in short reservoirs such as Oxbow and Hells Canyon

97 Snake River White Sturgeon Conservation Plan Idaho Power Company reservoirs are too uncertain at this time. Hatchery supplementation could be a tool for restoring the population by rebuilding sturgeon abundance in reaches where numbers are low and eventually increasing future productivity as stocked fish mature. However, Oxbow and Hells Canyon reservoirs lack the potential for supporting self-sustaining populations based on natural recruitment. These reaches are composed almost entirely of reservoir habitats. Therefore, periodic hatchery supplementation would probably be required to maintain some desired level of population abundance, making the long-term benefit of this action questionable. The cost of hatchery supplementation in terms of lost reproduction to the donor population that would result from removing broodstock must also be weighed against the anticipated benefits of supplementing Oxbow and Hells Canyon reservoirs. Other factors, such as disease outbreaks or genetic implications that could accrue from selective hatchery practices, could expose the adjacent downstream Hells Canyon–Lower Granite sturgeon population to unnecessary risk. Although sturgeon conservation aquaculture employs methods to minimize risk to wild stocks, such programs are still largely experimental and have yet to demonstrate their long-term effectiveness in preserving white sturgeon populations.

Conservation aquaculture has been proposed as a potential tool for population restoration in the Shoshone Falls–Upper Salmon Falls and Swan Falls–Brownlee reaches. These two reaches appear better suited for experimental hatchery supplementation because of their spatial separation from the stronghold (Bliss–C.J. Strike and Hells Canyon–Lower Granite) sturgeon populations. It would be prudent to determine the effectiveness of conservative hatchery measures in these reaches where the risks are not as great before implementing hatchery supplementation efforts in Oxbow and Hells Canyon reservoirs. Although this approach may be conservative, the uncertainty about the long-term effectiveness of hatchery supplementation for preserving white sturgeon populations, coupled with the cost (removal of reproduction) to donor populations, makes this alternative undesirable at this time.

• Monitor success of white sturgeon spawning and early life stage survival.

This recommendation is not applicable because translocation is not proposed for Oxbow and Hells Canyon reservoirs.

• Develop a genetics plan that addresses the current status and implications of translocations and potential hatchery introductions.

This recommendation is not applicable because translocation and hatchery supplementation are not proposed for Oxbow and Hells Canyon reservoirs. However, monitoring genotypic frequencies of sturgeon would be conducted during periodic population assessments of Oxbow and Hells Canyon reservoirs.

• Determine the feasibility of passage at the Hells Canyon Complex.

IPC has evaluated a full range of sturgeon passage alternatives, as well as the constraints associated with passing white sturgeon upstream and downstream of the HCC (Wittmann-Todd et al. 2001). Passage options were based on information from Russian and Columbia River sturgeon-passage facilities. Wittmann-Todd et al. (2001) concluded that the most feasible and practical alternative was capture and transport (i.e., translocation). The capture-and-transport

98 Idaho Power Company Snake River White Sturgeon Conservation Plan alternative can be accomplished with existing technology and represents the most reliable solution for passing sturgeon at this time. Capture-and-transport techniques have been used successfully by ODFW for transporting white sturgeon among lower Columbia River reservoirs to mitigate for lost recruitment and passage (Rien and North 2002). All other options explored by Wittmann-Todd et al. (2001) (including fish ladders, locks, lifts, pressured passage systems, trap and transport, surface collections, spillway releases, behavior guidance structures, and turbine exclusion) have considerable biological uncertainties, particularly those options relying on volitional responses. Sturgeon behavior does not necessarily favor voluntary upstream passage via facilities that have been effective for other species (Cooke et al. 2002). That is, passage measures are generally not a “good bet” for white sturgeon recovery in the Columbia and Snake River systems: fish ladders and collection systems designed for salmonids do not work for juvenile and adult sturgeon (R. Beamesderfer, S. P. Cramer and Associates, personal communication).

In addition, attempting to engineer passage solutions for sturgeon might backfire if adults were passed into reservoirs without suitable spawning habitats and then trapped there. Passing white sturgeon from below Hells Canyon Dam where riverine habitats currently support reproduction into upstream reservoir environments (such as Oxbow and Hells Canyon reservoirs) that provide little or no opportunity for natural production warrants careful consideration of the anticipated benefits of constructing sturgeon-passage facilities at the HCC. The general inability of reservoir habitats to support adequate levels of natural production for population growth and maintenance has been observed in several other reservoirs in the Columbia River basin. White sturgeon populations that have low and annually variable recruitment include those in the lower Columbia River reservoirs while recruitment is virtually nonexistent in the middle and upper Columbia River reservoirs (Parsley et al. 1993, Beamesderfer et al. 1995, UCWSRI 2002). As a result, translocation of juveniles among lower Columbia River reservoirs and hatchery supplementation within middle and upper Columbia River reservoirs are currently being evaluated as potential measures for supplementing failed natural recruitment and rebuilding declining stocks (UCWSRI 2002, Ward 2002).

• Evaluate the feasibility of dam removal.

IPC does not support or consider decommissioning as an option for the relicensing of the HCC. IPC believes studying the removal of the HCC, as an alternative for white sturgeon, would expend resources that would be better spent on developing realistic, environmentally sound, and socially and economically prudent mitigation measures.

• Improve water temperature conditions in Oxbow and Hells Canyon reservoirs.

The HCC, under its current configuration and operations already provides water quality benefits to downstream anadromous fish, including white sturgeon. Temperature conditions below the HCC comply with temperature standards more frequently than water flowing into Brownlee Reservoir. If temperature is an issue for white sturgeon populations associated with the HCC, a comprehensive watershed approach would be a more appropriate way to address the issue rather than arbitrarily and inequitably requiring IPC to further improve conditions.

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9.8 Hells Canyon–Lower Granite Reach

• Implement seasonal run-of-river project operations at Hells Canyon Dam during the spawning, incubation, and larval life stages of white sturgeon development (time frame TDB).

IPC does not support seasonal ROR project operations at Hells Canyon Dam for white sturgeon. While Chandler et al. (2002) reported that project operations at Hells Canyon Dam could reduce the availability of modeled habitat for early life stages of white sturgeon during low-flow water years, the size structure of the Hells Canyon population suggests continuous recruitment. Stock assessments conducted between 1972 and 2000 indicated positive and consistent recruitment trends, with juveniles dominating the population. The current population structure closely resembles IDFG’s desired management goal of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL. Overall, the sturgeon population below Hells Canyon Dam is genetically diverse and exhibits a healthy population structure based on a stock structure dominated by juveniles with a wide range of size classes and stages of maturity from immature juveniles to reproductive adults.

• Improve water temperature conditions below Hells Canyon Dam.

The HCC, under its current configuration and operations already provides water quality benefits to downstream anadromous fish, including white sturgeon. Temperature conditions below the HCC comply with temperature standards more frequently than water flowing into Brownlee Reservoir. If temperature is an issue for white sturgeon populations associated with the HCC, a comprehensive watershed approach would be a more appropriate way to address the issue rather than arbitrarily and inequitably requiring IPC to further improve conditions.

9.9. Recommended Measures Not Specific to White Sturgeon

• Determine off-site mitigation for on-going losses and impacts to white sturgeon between Brownlee and Hells Canyon dams.

It is not clear what is meant by “off-site” mitigation. However, it appears that off-site mitigation is not a technical/biological issue designed to improve or enhance white sturgeon in the Snake River and is therefore outside of the scope of this document. The WSCP identifies PM&E measures for Snake River white sturgeon populations impacted by IPC’s hydroelectric projects.

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10. LITERATURE CITED

Amaral, S. V., B. J. McMahon, J. L. Black, F. C. Winchell, and D. A. Dixon. 2001. Fish guidance efficiency of angled bar racks and louvers. Waterpower XII, July 9−11, 2001. Salt Lake, UT.

Anders, P. J. 1998. Conservation aquaculture and endangered species: Can objective science prevail over risk anxiety? Fisheries 23(11):28−31.

Anders, P. J. 2002. Biological description of white sturgeon (Acipenser transmontanus). Chapter 1 in P. J. Anders. Conservation biology of white sturgeon (Acipenser transmontanus). Doctoral dissertation. University of Idaho, Moscow ID. 221 p.

Anders, P. J. 2003. Don’t save sturgeon with salmon hatcheries: Life history matters. Submitted May 2003 to Fisheries.

Anders, P. J., C. R. Gelok, and M. S. Powell. 2000. Assessing genetic variation among Columbia Basin white sturgeon populations. Annual report to the U.S. Department of Energy. Bonneville Power Administration, Portland, OR. Contract 99-BI-16061, Project No. 99-22.

Anders, P. J., and M. S. Powell. 1999. Assessing genetic variability among populations of Columbia Basin white sturgeon. Annual report to the U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract 99-BI-16061, Project No. 99-22.

Anders, P. J., and M. S. Powell. 2002. Population structure and mitochondrial DNA diversity of North American white sturgeon (Acipenser transmontanus): An empirical expansive gene flow model. Chapter 3 in P. J. Anders. Conservation biology of white sturgeon (Acipenser transmontanus). Doctoral dissertation. University of Idaho, Moscow, ID. 38 p. Also submitted to the Journal of Applied Ichthyology.

Anders, P. J., D. L. Richards, and M. S. Powell. 2002. The first endangered white sturgeon population (Acipenser transmontanus): Repercussions in an altered large river-floodplain ecosystem. Pages 67−82 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Anglin, D. R., T. R. Cummings, and A. E. Ecklund. 1992. Swan Falls instream flow study. U.S. Department of the Interior, Fish and Wildlife Service, Lower Columbia Fisheries Resource Office, Vancouver, WA. A cooperative study by the U.S. Fish and Wildlife Service and Idaho Power Company. Report No. AFF1-FRO-92-14.

101 Snake River White Sturgeon Conservation Plan Idaho Power Company

Apperson, K., and P. J. Anders. 1990. Kootenai River white sturgeon investigations and experimental culture. Annual progress report FY 1990. Idaho Department of Fish and Game, Boise, ID, and the U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-88BP93497, Project No. 88-65.

Apperson, K., and P. J. Anders. 1991. Kootenai River white sturgeon investigations and experimental culture. Annual progress report FY 1990. Idaho Department of Fish and Game, Boise, ID, and the U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-88BP93497, Project No. 88-65. 67 p.

Auer, N. A. 1996. Importance of habitat and migration to sturgeons with emphasis on lake sturgeon. Canadian Journal of Fisheries and Aquatic Science 53(Supplement 1):152−160.

Avise, J. C. 1994. Molecular markers, natural history and evolution. Sinauer Associates, Sunderland, MA.

Avise, J. C., J. Arnold, R. M. Ball, E. Bermingham, T. Lamb, J. E. Neogel, C. A. Reeb, and N. C. Saunders. 1987. Intraspecific phylogeography: The mitochondrial DNA bridge between population genetics and systematics. Annual Review of Ecology and Systematics 18:489−522.

Bajkov, A. D. 1949. A preliminary report on the Columbia River sturgeon. Fisheries Commission of Oregon, Portland, OR. Research Briefs 2(2):1−8.

Bajkov, A. D. 1951. Migration of white sturgeon (Acipenser transmontanus) in the Columbia River. Fisheries Commission of Oregon, Portland, OR. Research Briefs 3(2):8−21.

Bartley, D. M., G. A. E. Gall, and B. Bentley. 1985. Preliminary description of the genetic structure of white sturgeon, Acipenser transmontanus in the Pacific Northwest. In F. P. Binkowski and S. I. Doroshov, editors. North American sturgeons: Biology and aquacultural potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

Beamesderfer, R. C. 1993. A standard weight (Ws) equation for white sturgeon. California Fish and Game 79(2):63−69.

Beamesderfer, R. C., and R. A. Farr. 1997. Alternatives for the protection and restoration of sturgeons and their habitat. Pages 407−417 in V. J. Birstein, J. R. Waldman, and W. E. Bemis, editors. Sturgeon biodiversity and conservation. Kluwer Academic Publishers, Dordrecht, Netherlands.

Beamesderfer, R. C., T. A. Rien, and A. A. Nigro. 1995. Differences in the dynamics and potential production of impounded and unimpounded white sturgeon population in the lower Columbia River. Transaction of the American Fisheries Society 124:857−872.

Bemis, W. E., and B. Kynard. 1997. An introduction to acipenseriform biogeography and life history. Environmental Biology of Fishes 48:167−183.

102 Idaho Power Company Snake River White Sturgeon Conservation Plan

Binkowski, F. P., and S. I. Doroshov. 1985. North American sturgeons: Biology and aquacultural potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

Birstein, V. J. 1993. Sturgeons and paddlefishes: Threatened fishes in need of conservation. Conservation Biology 7:773−787.

Booth, R. K., J. D. Kieffer, K. Davidson, A. Bielak, and B. L. Tufts. 1995. Effects of late-season catch and release angling on anaerobic metabolism, acid-base status, survival, and gamete viability in wild Atlantic salmon (Salmo salar). Canadian Journal of Fisheries and Aquatic Science 52:283−290.

Bouck, G. R. 1980. Etiology of gas bubble disease. Transactions of the American Fisheries Society 109(6):703−707.

Boyce, M. S. 1992. Population viability analysis. Annual Review of Ecology and Systematics 23:481−506.

Brannon, E., S. Brewer, A. Setter, M. Miller, F. Utter, and W. Hershberger. 1985. Columbia River white sturgeon (Acipenser transmontanus) early life history and genetics study. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. DOE/BP-18952-1.

Brannon, E. L., C. L. Melby, and S. D. Brewer. 1984. Columbia River white sturgeon (Acipenser transmontanus) enhancement. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-84BP18952, Project No. 83-316.

Brannon, E., and A. Setter. 1992. Movements of white sturgeon in Lake Roosevelt. Final report 1988–1991. U.S. Department of Energy, Bonneville Power Administration, Division of Fish and Wildlife, Portland, OR. Project No. 89-44. 35 p.

Brannon, E., A. Setter, M. Miller, S. Brewer, G. Winans, F. Utter, L. Carpenter, and W. Hershberger. 1986. Columbia River white sturgeon genetics and early life history population segregation and juvenile feeding behavior. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-84BP18952, Project No. 83-316.

Brink, S. R. 2000. Response to FERC additional information request #16: Wetted streambed area below Lower Salmon Falls (updated Lower Salmon Falls instream flow study). Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Brink, S. R., and J. A. Chandler. 2000. Response to FERC additional information request #1a: Project flows (Bliss instream flow study). Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Brown, M. 2002. Recreational use associated with the Snake River in the Hells Canyon National Recreation Area. Technical Report E.5-3 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

103 Snake River White Sturgeon Conservation Plan Idaho Power Company

Buddington, R. K., and J. P. Christofferson. 1985. Digestive and feeding characteristics of the chondrosteans. Pages 31−42 in F. P. Binkowski and S. I. Doroshov, editors. North American sturgeons: Biology and aquaculture potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

Burggren, W. W., and D. J. Randall. 1978. Oxygen uptake and transport during hypoxic exposure in the sturgeon Acipenser transmontanus. Respiratory Physiology 34:171−183.

Caballero, A. 1994. Developments in the prediction of effective population size. Heredity 73:657−679.

Cech, J. J., Jr., S. J. Mitchell, and T. E. Wragg. 1984. Comparative growth of juvenile white sturgeon and striped bass: Effects of temperature and hypoxia. Estuaries 7:12−18.

Chandler, J. A. 2001. Integration of aquatic studies in the Hells Canyon relicensing. Technical Report E.3.1-1 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Chandler, J. A., S. Brink, and S. K. Parkinson. 2002. Hells Canyon instream flow assessment. Technical Report E.2.3-2 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Chandler, J. A., and K. B. Lepla. 1997. Instream flow evaluations of the Snake River from C.J. Strike Dam to the confluence of the Boise River. Technical Report E.3.1-C in Volume 1, Technical appendices for C.J. Strike new license application. Idaho Power Company, Boise, ID.

Chapman, F. A., J. P. Van Eenennaam, and S. I. Doroshov. 1996. The reproductive condition of white sturgeon, Acipenser transmontanus, in San Francisco Bay, California. Fishery Bulletin 94:628−634.

Clark, G. M. 1994. Assessment of selected constituents in surface water of the upper Snake River, Idaho, and western Wyoming, water years 1975−1989. U.S. Geological Survey Water Resources Investigations Report 93–4229.

Clark, G. M., T. R. Maret, M. G. Rupert, M. A. Maupin, W. H. Low, and D. S. Ott. 1998. Water quality in the upper Snake River basin, Idaho and Wyoming, 1992–95. U.S. Geological Survey Circular 1160. 35 p.

Cochnauer, T. G. 1981. Survey status of white sturgeon populations in the Snake River, Bliss Dam to C.J. Strike Dam. Job performance report. Idaho Department of Fish and Game, River and Stream Investigations, Boise, ID. Project F-73-R-3, Job I-b.

Cochnauer, T. G. 1983. Abundance, distribution, growth and management of white sturgeon (Acipenser transmontanus) in the middle Snake River, Idaho. Doctoral dissertation. University of Idaho, Moscow, ID.

104 Idaho Power Company Snake River White Sturgeon Conservation Plan

Cochnauer, T. G. 2002. Response to catch and release regulations on white sturgeon—now what? Pages 83−87 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Cochnauer, T. G., J. R. Lukens, and F. E. Partridge. 1985. Status of white sturgeon, Acipenser transmontanus, in Idaho. In P. P. Binkowski and S. I. Doroshov, editors. North American sturgeons: Biology and aquacultural potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

Collier, M., R. Webb, and J. Schmidt. 1996. Dams and rivers: A primer on the downstream effects of dams. U.S. Geological Survey Circular 1126. 93 p.

Conte, F. S., S. I. Doroshov, P. B. Lutes, and E. M. Strange. 1988. Hatchery manual for the white sturgeon Acipenser transmontanus with application to other North American Acipenseridae. Cooperative Extension, University of California, Division of Agriculture and Natural Resources, Davis, CA. Publication 3322.

Cooke, D. W., S. D. Leach, and I. J. Isely. 2002. Behavior and lack of upstream passage of shortnose sturgeon at a hydroelectric facility and navigation lock complex. Pages 101−110 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Coon, J. C. 1978. Movement, distribution, abundance and growth of white sturgeon in the mid-Snake River. Doctoral dissertation. Forest, Wildlife, and Range Experiment Station, University of Idaho, Moscow, ID.

Coon, J. C., R. R. Ringe, and T. C. Bjornn. 1977. Abundance, growth, distribution and movements of white sturgeon in the mid-Snake River. Forest, Wildlife, and Range Experiment Station, Idaho Water Resources Research Institute, University of Idaho, Moscow, ID. Contribution 97.

Counihan, T. D., J. D. DeVore, and M. J. Parsley. In press. The effect of river discharge and water temperature on the year-class strength of Columbia River white sturgeon. Transactions of the American Fisheries Society.

Counihan, T. D., A. I. Miller, M. G. Mesa, and M. J. Parsley. 1998. The effects of dissolved gas supersaturation on white sturgeon larvae. Transactions of the American Fisheries Society 127(20):316−322.

Counihan, T. D., and M. Parsley. 2001. Effects of hydropower peaking dam operations on white sturgeon eggs and larvae in the Columbia River. U.S. Geological Survey, Cook, WA.

Crocker, C. E., and J. J. Cech, Jr. 1997. Effects of environmental hypoxia on oxygen consumption rate and swimming activity in juvenile white sturgeon, Acipenser transmontanus, in relation to temperature and life intervals. Environmental Biology of Fishes 50:383−389.

105 Snake River White Sturgeon Conservation Plan Idaho Power Company

DeVore, J. D., and J. G. Grimes. 1993. Migration and distribution of white sturgeon in the Columbia River downstream from Bonneville Dam and adjacent marine areas. In R. C. Beamesderfer and A. A. Nigro, editors. Volume I, Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Duke, S., P. Anders, G. Ennis, R. Hallock, J. Hammond, S. Ireland, J. Laufle, L. Lockard, B. Marotz, V. Paragamian, and R. Westerhof. 1999. Recovery plan for Kootenai River white sturgeon (Acipenser transmontanus). Journal of Applied Ichthyology (15):157−163.

Duke, S. D., T. J. Underwood, G. M. Asbridge, R. G. Griswold, M. J. Parsley, and L. G. Beckman. 1990. In A. A. Nigro, editor. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Annual progress report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Edson, M. 1956. The sturgeon story. Idaho Wildlife Review 9(2):4−9.

Everett, S. R., and M. A. Tuell. 2003. Evaluate potential means of rebuilding sturgeon populations in the Snake River between Lower Granite and Hells Canyon dams. Preliminary draft of the 2000 annual report to the U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract 00000333-00023, Project No. 199700900.

Federal Energy Regulatory Commission (FERC). 2002a. Final environmental impact statement for hydropower relicensing. Four Mid-Snake River Projects Idaho: Shoshone Falls— FERC Project No. 2778, Upper Salmon Falls—FERC Project No. 2777, Lower Salmon Falls—FERC Project No. 2061, and Bliss—FERC Project No. 1975. FERC, Office of Energy Projects, Division of Engineering and Environmental Review, Washington, DC. FERC/FEIS-0141F.

Federal Energy Regulatory Commission (FERC). 2002b. Final environmental impact statement for hydropower relicensing. C.J. Strike—FERC Project No. 2055. FERC, Office of Energy Projects, Division of Engineering and Environmental Review, Washington, DC. FERC/FEIS-0146F.

Foster, E. P. 2002. Evaluate white sturgeon nutritional needs and contaminant effects influenced by the hydroelectric system. BPA project proposal FY 2003. U.S. Department of Energy, Bonneville Power Administration. Mainstem/Systemwide Province Proposal, Project No. 35028.

Frankham, R. 1995. Effective population size/adult population size ratios in wildlife: A review. Genetical Research 66:95−107.

106 Idaho Power Company Snake River White Sturgeon Conservation Plan

Galbreath, J. L. 1985. Status, life history, and management of Columbia River white sturgeon, Acipenser transmontanus. Pages 119−125 in F. P. Binkowski and S. I. Doroshov, editors. North American sturgeons: Biology and aquaculture potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

Galbreath, J. 1979. Columbia River colossus—the white sturgeon. Oregon Wildlife 34(3):3−8.

Gross, M., J. Repka, C. Robertson, D. Secor, and W. Van Winkle. 2002. Sturgeon conservation: Insights from elasticity analysis. Pages 13−29 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Hanson, D. L., T. G. Cochnauer, J. D. DeVore, H. E. Forner, T. T. Kisanuki, D. W. Kohlhorst, P. Lumley, G. McCage, A. A. Nigro, S. Parker, D. Swartz, and A. VanVooren. 1992. White sturgeon management framework plan. Pacific States Marine Fisheries Commission, Portland, OR.

Harrison, J., S. Wells, R. Myers, S. Parkinson, and M. Kasch. 1999. 1999 status report on Brownlee Reservoir water quality and model development. Draft technical report. Idaho Power Company, Boise, ID. 70 p.

Harrison, J., S. Wells, R. Myers, S. Parkinson, M. Kasch, and C. Berger. October 2000. 2000 status report on southwest Snake River water quality and model Development. Draft report. Idaho Power Company, Boise, ID.

Haynes, J. M., R. H. Gray, and J. C. Montgomery. 1978. Seasonal movements of white sturgeon (Acipenser transmontanus) in the mid-Columbia River. Transaction of the American Fisheries Society 107(2):275−280.

Hjort, J. 1926. Fluctuations in the year classes of important food fishes. Journal du Conseil International pour l’Exploration de la mer 1; pp. 5−38.

Hoelscher, B., and R. Myers. 2001. Tributary pollutant sources in the Hells Canyon Complex. Technical Report E.2.2-1 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Idaho Department of Environmental Quality (IDEQ [formerly Idaho Division of Environmental Quality]). 1998. Idaho’s 1998 303 (d) list. IDEQ, Idaho State Office, Boise, ID. 13 p.

Idaho Department of Environmental Quality (IDEQ). 2000. Bruneau subbasin assessment and total maximum daily loads of the 303 (d) water bodies. IDEQ, Twin Falls Regional Office, Twin Falls, ID.

Idaho Department of Environmental Quality (IDEQ) and Oregon Department of Environmental Quality (ODEQ). December 2001. Snake River–Hells Canyon total maximum daily load (TMDL). Draft plan. IDEQ, Boise Regional Office, Boise, ID, and ODEQ, LaGrande Office, LaGrande, OR. 575 p.

107 Snake River White Sturgeon Conservation Plan Idaho Power Company

Idaho Department of Fish and Game (IDFG). 1990. Letter to the Office of the Governor from Will Reid, IDFG Fisheries Program Coordinator. Dated August 3, 1990.

Idaho Department of Fish and Game (IDFG). August 1992. Idaho white sturgeon management plan. Draft plan. IDFG, Boise, ID.

Idaho Department of Fish and Game (IDFG). August 5, 1995. Sturgeon newsletter 2:1−4.

Idaho Department of Fish and Game (IDFG). June 1996. Sturgeon newsletter 4:1−4.

Idaho Department of Fish and Game (IDFG). 2001. Fisheries management plan, 2001−2006. IDFG, Boise, ID.

Idaho Department of Fish and Game (IDFG). December 2002. White sturgeon management plan: Status and objectives of Idaho’s white sturgeon resources in the Snake River. Draft plan. IDFG, Boise, ID.

Idaho Power Company (IPC). April 2000a. Response to FERC additional information request #37: Eutrophication conditions, middle Snake River. Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Idaho Power Company (IPC). October 2000b. Response to FERC additional information request #4: Water quality data analysis. Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Idaho Power Company (IPC). October 2000c. Response to FERC additional information request #8: Total dissolved gas at C.J. Strike reservoir. Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Idaho Power Company (IPC). October 2000d. Response to FERC additional information request #7: Improvements in dissolved oxygen for C.J. Strike. Report to the Federal Energy Regulatory Commission. Idaho Power Company, Boise, ID.

Ireland, S. C., P. J. Anders, and J. T. Siple. 2002. Conservation aquaculture: An adaptive approach to prevent extinction of an endangered white sturgeon population. Pages 211−222 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Jager, H. I., J. Chandler, K. Lepla, and W. Van Winkle. 2001a. A theoretical study of river fragmentation by dams and its effects on white sturgeon populations. Environmental Biology of Fishes 60:347−361.

Jager, H., K. Lepla, J. A. Chandler, W. Van Winkle, A. Sullivan, R. Myers, and M. Bevelhimer. 2001b. Population viability model for Snake River white sturgeon. In K. Lepla, editor. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical Report E.3.1-6, Chapter 3, in Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power Company, Boise, ID.

108 Idaho Power Company Snake River White Sturgeon Conservation Plan

Jager, H., W. Van Winkle, J. A. Chandler, K. B. Lepla, P. Bates, and T. D. Counihan. 2002. A simulation study of factors controlling white sturgeon recruitment in the Snake River. Pages 127–150 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28, American Fisheries Society, Bethesda, MD.

Kern, J. C., T. A. Rien, and R. A. Farr. 2001. Report A. Pages 6−40 in D. L. Ward, editor. White sturgeon mitigation and restoration in the Columbia and Snake rivers upstream from Bonneville Dam. Annual progress report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Project No. 86-50.

Klyashtorin, L. B. 1974. The sensitivity of young sturgeons to oxygen deficiency. Journal of Ichthyology 16:677−682.

Kohlhorst, D. W. 1976. Sturgeon spawning in the Sacramento River in 1973, as determined by distribution of larvae. California Fish and Game 62(1):32−40.

Kohlhorst, D. W., L. W. Botsford, J. S. Brennan, and G. M. Cailliet. 1989. Aspects of the structure and dynamics of an exploited central California population of white sturgeon (Acipenser transmontanus). In Acipenser. Actes du Premier Coloque International sur l’Esturgeon, Bordeaux, France. p. 277−293.

Kruse, G. O. 2000. The effects of contaminants on reproduction, embryo development and related physiological processes in Kootenai River white sturgeon, Acipenser transmontanus Richardson. M.Sc. thesis. University of Idaho, Moscow, ID.

Kruse-Malle, G. O. 1993. White sturgeon evaluations in the Snake River. Job performance report. Idaho Department of Fish and Game, Boise, ID. Project F-73-R-15.

Kynard, B., and M. Horgan. 2001. Guidance of yearling shortnose and pallid sturgeon using vertical bar rack and louver arrays. North American Journal of Fisheries Management 21:561−570.

Lambert, Y., and J. Dutil. 2000. Energetic consequences of reproduction in Atlantic cod (Gadus morhua) in relation to spawning level of somatic energy reserves. Canadian Journal of Fisheries and Aquatic Science 57(4):815−825.

Lepla, K. B., and J. A. Chandler. 1995a. A survey of white sturgeon in the Bliss reach of the Snake River, Idaho. Technical Report E.3.1-E in Volume 1, Technical appendices for new license application: Upper Salmon Falls, Lower Salmon Falls, and Bliss. Idaho Power Company, Boise, ID. 96 p.

Lepla, K. B., and J. A. Chandler. 1995b. A survey of white sturgeon in the Lower Salmon Falls reach of the Snake River, Idaho. Technical Report E.3.1-B in Volume 1, Technical appendices for new license application: Upper Salmon Falls, Lower Salmon Falls, and Bliss. Idaho Power Company, Boise, ID. 31 p.

109 Snake River White Sturgeon Conservation Plan Idaho Power Company

Lepla, K. B., and J. A. Chandler. 1997. Status of white sturgeon in the C.J. Strike reach of the middle Snake River, Idaho. Technical Report E.3.1-B in Volume 1, Technical appendices for C.J. Strike new license application. Idaho Power Company, Boise, ID. 71 p.

Lepla, K. B., and J. A. Chandler. 2001. Physical habitat use and water quality criteria for Snake River white sturgeon. In K. Lepla, editor. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical Report E.3.1-6, Chapter 2, in Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power Company, Boise, ID.

Lepla, K. B., J. Anderson, and P. Bates. 2002. An assessment of white sturgeon in the Shoshone Falls–Upper Salmon Falls reach of the Snake River. Idaho Power Company, Boise ID. 48 p.

Lepla, K. B., J. A. Chandler, and P. Bates. 2001. Status of Snake River white sturgeon associated with the Hells Canyon Complex. In K. Lepla, editor. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical Report E.3.1-6, Chapter 1, in Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power Company, Boise, ID.

Lukens, J. R. 1981. Snake River sturgeon investigations (Bliss Dam upstream to Shoshone Falls). Idaho Department of Fish and Game, Boise, ID. 24 p.

Lukens, J. R. 1985. Hells Canyon white sturgeon investigations. Job performance report. Idaho Department of Fish and Game, River and Stream Investigations, Boise, ID. Project F-73-R-7.

McCabe, G. T., and S. A. Hinton. 1990. Report D. In A. A. Nigro, editor. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Annual progress report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

McCabe, G. T., Jr., and C. A. Tracy. 1993. Spawning characteristics and early life history of white sturgeon Acipenser transmontanus in the lower Columbia River. In R. C. Beamesderfer and A. A. Nigro, editors. Volume I, Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

McCabe, G. T., Jr., and C. A. Tracy. 1994. Spawning and early life history of white sturgeon, Acipenser transmontanus, in the lower Columbia River. Fishery Bulletin 92:760−772.

McConnell, W. J. 1989. Habitat suitability curves for white sturgeon. U.S. Fish and Wildlife Service, National Ecology Center, Fort Collins, CO.

110 Idaho Power Company Snake River White Sturgeon Conservation Plan

McElhany, P., M. H. Ruckleshaus, M. J. Ford, T. C. Wainwright, and E. P. Bjorkstedt. 2000. Viable salmonid populations and the recovery of evolutionarily significant units. National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center, Seattle, WA. NOAA Technical Memorandum NMFS-NWFSC-42.

McKechnie, R. J., and R. B. Fenner. 1971. Food habits of white sturgeon, (Acipenser transmontanus), in San Pablo and Suisun Bays, California Fish and Game 57(3):209−212.

McQuown, E. C., B. L. Sloss, R. J. Sheehan, J. A. Rodzen, G. J. Tranah, and B. May. 2000. Microsatellite analysis of genetic variation in sturgeon: New primer sequences for Scaphirhynchus and Acipenser. Transactions of the American Fisheries Society 129:1380−1388.

Miller, A. I., and L. G. Beckman. 1995. Predation on white sturgeon eggs by sympatric fish species in three Columbia River impoundments. In R. C. Beamesderfer and A. A. Nigro, editors. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. U.S. Department of Energy, Bonneville Power Administration, Portland, OR.

Miller, S., D. Glanzman, S. Doran, S. K. Parkinson, J. Buffington, and J. Milligan. 2002. Geomorphology of the Hells Canyon reach of the Snake River. Technical Report E.1-2 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Mosley, R., and C. Groves. 1990. Rare, threatened, and endangered plants and animals of Idaho. Idaho Department of Fish and Game, Natural Heritage Section, Boise, ID.

Moursund, R. A., K. D. Ham, P. S. Titzler, R. P. Mueller, G. E. Johnson, J. Hedgepeth, and J. R. Skalski. 2002. Hydroacoustic evaluation of fish passage at The Dalles Dam in 2001. Prepared for the U.S Army Corps of Engineers, Portland OR.

Muir, W. D., R. L. Emmett, and R. J. McConnell. 1988. Diet of juvenile and subadult white sturgeon in the lower Columbia River and its estuary. California Fish and Game 74:49−54.

Myers, R., and J. A. Chandler. 2001. Oxbow Bypass minimum flow evaluation. Technical Report E.2.3-1 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Myers, R., J. Harrison, S. K. Parkinson, B. Hoelscher, J. Naymik, and S. E. Parkinson. 2001. Pollutant transport and processing in the Hells Canyon Complex. Technical Report E.2.2-2 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

Myers, R., and S. E. Parkinson. 2002. Hells Canyon Complex total dissolved gas study. Technical Report E.2.2-4 in Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power Company, Boise, ID.

111 Snake River White Sturgeon Conservation Plan Idaho Power Company

Myers, R., and S. Pierce. 1997. Limnological survey of the C.J. Strike Hydroelectric Project. Technical Report E.2.2-A in Volume 1, Technical appendices for C.J. Strike new license application. Idaho Power Company, Boise, ID. 71 p.

Myers, R., and S. Pierce. November 1999. Descriptive limnology of the Hells Canyon Complex. Draft progress report. Idaho Power Company, Boise, ID.

Myers, R., S. Pierce, and C. Randolph. May 1995. Descriptive limnological study of the Snake River, Idaho: Buhl to King Hill. Technical Report E.2.2-A in Volume 1, Technical appendices for new license application: Upper Salmon Falls, Lower Salmon Falls, and Bliss. Idaho Power Company, Boise, ID.

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). September 1998. Status review of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). U.S. Department of Commerce, National Oceanic and Atmospheric Administration, NMFS, and U.S. Department of the Interior, USFWS. 126 p. Available at .

Nei, M. 1987. Molecular evolutionary genetics. Columbia University Press. 512 p. Available at .

Nei, M., and F. Tajima. 1981. DNA polymorphisms detectable by restriction endonucleases. Genetics 97:145−163.

Nelson, K. L. 1998. Catch-and-release mortality of striped bass in the Roanoke River, North Carolina. North American Journal of Fisheries Management 18:25−30.

North, J. A., R. C. Beamesderfer, and T. A. Rien. 1993. Distribution and movements of white sturgeon in three lower Columbia River reservoirs. In R. C. Beamesderfer and A. A. Nigro, editors. Volume I, Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Pacific States Marine Fisheries Commission (PSMFC). 1992. White sturgeon management framework plan. Prepared by the White Sturgeon Planning Committee, PSMFC, Portland, OR. 201 p.

Palmer, T. 1991. The Snake River: Window to the West. Island Press, Washington, D.C.

Parsley, M. J., and L. G. Beckman. 1994. White sturgeon spawning and rearing habitat in the lower Columbia River. North American Journal of Fisheries Management 14:812−827.

Parsley, M. J., L. G. Beckman, and G. T. McCabe, Jr. 1993. Spawning and rearing habitat use by white sturgeons in the Columbia River downstream from McNary Dam. Transactions of the American Fisheries Society 122:217−227.

112 Idaho Power Company Snake River White Sturgeon Conservation Plan

Parsley, M. J., S. D. Duke, T. J. Underwood, and L. G. Beckman. 1989. Report C. In A. A. Nigro, editor. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Annual progress report. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Partridge, F. 1983. Kootenai River fisheries investigations. Job completion report. Idaho Department of Fish and Game, River and Stream Investigations, Boise, ID. Project F-73-R-5.

Perrin, C. J., L. L. Rempel, and M. L. Rosenau. 2003. White sturgeon spawning habitat in an unregulated river: Fraser River, Canada. Transactions of the American Fisheries Society 132:154−165.

Plantania, S. P., and C. S. Altenbach. 1998. Reproductive strategies and egg types of seven Rio Grande basin cyprinids. Copeia 3:559−569.

Reid, W. W., W. H. Goodnight, and B. B. Bowler. 1973. Survey of fish populations in the Snake River above Brownlee Reservoir. Idaho Department of Fish and Game, Boise, ID. Federal Aid to Fish Restoration Project F-63-R-2.

Reid, W. W., and B. Mabbot. 1987. Regional fisheries management investigations: Region 3 (Boise) river and stream investigations. Idaho Department of Fish and Game, River and Stream Investigations, Boise, ID. Federal Aid to Fish Restoration Project F-71-R-11.

Rieman, B. E., and F. W. Allendorf. 2001. Effective population size and genetic conservation criteria for bull trout. North American Journal of Fisheries Management 21:756−764.

Rieman, B. E., and R. C. Beamesderfer. 1990. White sturgeon in the lower Columbia River: Is the stock overexploited? North American Journal of Fisheries Management 10:388−396.

Rien, T. A., and J. A. North. 2002. White sturgeon transplants within the Columbia River. Pages 223–236 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

RL&L Environmental Services Ltd. 2000. Fraser River white sturgeon monitoring program: Comprehensive report 1995–1999. Final report prepared for British Columbia Fisheries. RL&L Report 815F. 92 p. plus appendices.

Rodzen, J. A., and B. May. 2002. Inheritance of microsatellite loci in the white sturgeon (Acipenser transmontanus). Genome 45:1064−1076.

Ruer, P. M., J. J. Cech, Jr., and S. I. Doroshov. 1987. Routine metabolism of the white sturgeon, Acipenser transmontanus: Effect of population density and hypoxia. Aquaculture 62:45−52.

113 Snake River White Sturgeon Conservation Plan Idaho Power Company

Schreer, J. F., S. J. Cooke, and R. S. Mckinley. 2001. Cardiac response to variable forced exercise at different temperatures: An angling simulation for smallmouth bass. Transactions of the American Fisheries Society 130:783−795.

Schreiber, M. R. 1960. Observations on the systematics of juvenile white sturgeon and green sturgeon. California Department of Fish and Game, Inland Fisheries Administration. Report 60-15. 5 p.

Scott, W. B., and E. J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada, Ottawa, Canada. Bulletin 184.

Secor, D. H., P. J. Anders, W. Van Winkle, and D. A. Dixon. 2002. Pages 3−9 in W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Secor, D. H., V. Arevyev, A. Nikolaev, and A. Sharov. 2000. Restoration of sturgeons: Lessons from the Caspian Sea sturgeon ranching program. Fish and Fisheries 1:215−230.

Semakula, S. N., and P. A. Larkin. 1968. Age, growth, food and yield of the white sturgeon (Acipenser transmontanus) of the Fraser River, British Columbia. Fisheries Research Board of Canada 25(12):2589−2602.

Setter, A., and E. Brannon. 1992. A summary of stock identification research on white sturgeon of the Columbia River (1985−1990). Final report. U.S. Department of Energy, Bonneville Power Administration, Portland OR. Project No. 89-44.

Simpson, J., and R. Wallace. 1982. Fishes of Idaho. Northwest Naturalist Book, Moscow, ID. 238 p.

Smith, T. I. J. 1990. Culture of North American sturgeons for fishery enhancement. National Marine Fisheries Service Technical Report 85:19−27.

Smith, T. I. J., M. R. Collins, W. C. Post, and J. W. McCord. 2002. Stock enhancement of shortnose sturgeon: A case study. In W. Van Winkle, P. J. Anders, D. H. Secor, and D. A. Dixon, editors. Biology, management, and protection of North American sturgeon. Symposium 28. American Fisheries Society, Bethesda, MD.

Stockley, C. 1981. Columbia River sturgeon. Washington Department of Fisheries. Progress Report No. 150. 28 p.

Thompson, G. G. 1991. Determining minimum viable populations under the Endangered Species Act. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Seattle, WA. NOAA Technical Memorandum NMFS F/NMC-198.

Tsyplakov, E. P. 1978. Migrations and distribution of the sterlet Acipenser ruthenus in Kuybyshev reservoir. Journal of Ichthyology 18:905−912.

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Turner, J. L., and D. W. Kelly. 1966. Ecological studies of the Sacramento–San Joaquin delta, Part 2: Fishes in the delta. Fish Bulletin 136:120−129.

Upper Columbia White Sturgeon Recovery Initiative (UCWSRI). 2002. Upper Columbia white sturgeon recovery plan. Draft plan. British Columbia Ministry of Water, Land, and Air Protection, Nelson, BC.

U.S. Army Corps of Engineers (COE). 1994. CE-QUAL-W2, version 2.0. Prepared by Thomas M. Cole. U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS.

U.S. Bureau of Reclamation (USBR). 1998a. Biological assessment: Bureau of Reclamation operations and maintenance in the Snake River basin above Lower Granite Reservoir, Boise, Idaho. Combined report. USBR, Pacific Northwest Region, Boise, ID.

U.S. Bureau of Reclamation (USBR). 1998b. Biological assessment for operations and maintenance in Snake River basin above Lower Granite Reservoir. Operations manual. USBR, Pacific Northwest Region, Boise, ID.

U.S. Environmental Protection Agency (USEPA). 2001. EPA’s additions to the 1998 Idaho § 303 (d) list. USEPA, Region X, Seattle, WA. 3 p.

U.S. Environmental Protection Agency (USEPA). February 1, 2002. Ecological risk assessment for the middle Snake River, Idaho. USEPA, Office of Research and Development, National Center for Environmental Assessment, Washington Office, Washington, D.C. USEPA EPA/600/R-01/017. Available from National Technical Information Service, Springfield, VA, and .

U.S. Fish and Wildlife Service (USFWS). 1999. Recovery plan for the Kootenai River population of white sturgeon (Acipenser transmontanus). USFWS, Region 1, Portland, OR.

U.S. Geological Survey (USGS). 2000. Water resources data, Idaho, water year 2000. Water Data Reports ID-00-1 and ID-00-2, volumes 1 and 2.

Votinov, N. P., and V. P. Kas’yanov. 1978. The ecology and reproductive efficiency of the Siberian sturgeon, Acipenser baeri, in the Ob as affected by hydraulic engineering works. Journal of Ichthyology 18:20−29.

Ward, D. L., editor. 2002. White sturgeon mitigation and restoration in the Columbia and Snake rivers upstream of Bonneville Dam. Annual report, April 2000 to March 2001. U.S. Department of Energy, Bonneville Power Administration, Portland, OR. Report DOE/BP-000040005-1.

Wang, Y. L., F. P. Binkowski, and S. I. Doroshov. 1985. Effect of temperature on early development of white and lake sturgeon, Acipenser transmontanus and A. fulvescens. Pages 43−50 in F. P. Binkowski and S. I. Doroshov, editors. North American sturgeons: biology and aquaculture potential. Dr. W. Junk Publishers, Dordrecht, The Netherlands.

115 Snake River White Sturgeon Conservation Plan Idaho Power Company

Wang, Y. L., R. K. Buddington, and S. I. Doroshov. 1987. Influence of temperature on yolk utilization by the white sturgeon, Acipenser transmontanus. Journal of Fish Biology 30:263−271.

Webb, M. A. H. 2002. Determine effects of contaminants on white sturgeon reproduction and parental transfer of contaminants to embryos in the Columbia River basin. BPA project proposal FY 2003. U.S. Department of Energy, Bonneville Power Administration. Mainstem/Systemwide Province Proposal, Project No. 35044.

Weitkamp, D. E. 1974. Dissolved gas supersaturation in the Columbia River system: Salmonid bioassay and depth distribution studies. Parametrix, Inc., Environmental Services Section, Seattle, WA. 71 p.

Weitkamp, D. E., and M. Katz. 1980. A review of dissolved gas supersaturation literature. Transactions of the American Fisheries Society 109:659−702.

Welsh, T. L., and W. W. Reid. 1971. Hells Canyon fisheries investigations. 1970 annual report. Idaho Department of Fish and Game, Boise, ID.

Wilcove D. S., D. Rothstein, J. Dubow, A. Phillips, and E. Losos. 1998. Quantifying threats to imperiled species in the United States: Assessing the relative importance of habitat destruction, alien species, pollution, overexploitation and disease. Bioscience 48:607−615.

Winemiller, K. O., and K. A. Rose. 1992. Patterns of life-history diversification in North American fishes: Implications for population regulation. Canadian Journal of Fisheries and Aquatic Sciences 49:2196−2218.

Wittmann-Todd, S. W., M. R. Voskuilen, J. M. Etulain, S. Parkinson, and K. Lepla. 2001. Conceptual design for white sturgeon passage facilities at the Hells Canyon Complex. In K. Lepla, editor. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical Report E.3.1-6, Chapter 4, in Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power Company, Boise, ID.

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11. TABLES

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Table 1. Years that hydroelectric projects on the Snake River went into operation.

Online Project Current River Mile Reach Length (river Reservoir Length (river Date Ownership miles: dam→upstream) miles) 1901 Swan Falls IPC 458.0 36 10.8 1907 Shoshone Falls IPC 614.7 2.7 1.8 1910 Lower Salmon Falls IPC 573.0 7.8 7.2 1937 Upper Salmon Falls A IPC 579.6 1.2 - 1947 Upper Salmon Falls B IPC 580.8 33.9 4.7 1950 Bliss IPC 560.0 13 5 1952 C.J. Strike IPC 494.0 66 24 1959 Brownlee IPC 284.6 173 55 1961 Oxbow IPC 273.0 12 12 1962 Ice Harbor COE 9.7 31.9 31.9 1967 Hells Canyon IPC 247.6 26 22.3 1969 Lower Monumental COE 41.6 28.7 28.7 1970 Little Goose COE 70.3 37.2 37.2 1975 Lower Granite COE 107.5 140 37

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Table 2. Summary of storage facilities upstream of Hells Canyon Dam. (Source: Miller et al. 2002).

Total Mainstem/Tributary Facilities Current Owner Data Year Storage (Tributary Name) Or Operator Source Completed (acre-feet)

Jackson Lake Dam and Lake USBR A 1916 847,000 Palisades Dam and Reservoir USBR A 1957 1,401,000 Henrys Lake (Henry's Fork) North Fork Reservoir Company A 1923 90,300 Island Park Dam and Reservoir (Henry's Fork) USBR B 1938 135,586 Grassy Lake Dam and Reservoir (Henry's Fork) USBR B 1939 15,470 Grays Lake (Willow Creek) Bureau of Indian Affairs A 1924 400,000 Ririe Dam and Reservoir (Willow Creek) Corps of Engineers B 1977 100,541 Blackfoot Reservoir (Blackfoot River) Bureau of Indian Affairs A 1913 413,000 American Falls Dam and Reservoir USBR B 1927 1,672,590 Minidoka Dam and Lake Walcott USBR A 1906 210,200 Oakley Reservoir (Goose Creek) Oakley Canal Company D 1911 77,000 Milner Dam and Lake Twin Falls Canal Company A 1905 50,000 Twin Falls Idaho Power Company D 1935 955 Shoshone Falls Idaho Power Company C 1907 0 Salmon River Canal Reservoir (Salmon Falls Salmon River Canal Company D 1910 260,650 Creek) Upper Salmon Falls A Idaho Power Company C 1937 0 Upper Salmon Falls B Idaho Power Company C 1947 600 Lower Salmon Falls Idaho Power Company C 1949 10,900 Mormon (Twin Lakes) (Malad River) McKinney and Dairy Creeks A 1908 31,400 Magic Reservoir (Malad River) Big Wood Canal Company A 1917 191,500 Fish Creek Reservoir (Malad River) Carey Valley Reservoir A 1923 12,740 Company Little Wood A (Malad River) USBR A 1939 12,100 Little Wood B (Malad River) USBR A 1960 30,000 Bliss Idaho Power Company C 1950 8,415 C.J. Strike Idaho Power Company D 1952 250,000 Swan Falls Idaho Power Company C 1901 7,425 Owyhee Dam and Reservoir (Owyhee River) USBR A 1932 1,120,000 Antelope Dam and Reservoir (Owyhee River) Jordan Valley Irrigation District A 1935 26,300 Wild Horse Dam and Reservoir (Owyhee River) Bureau of Indian Affairs A 1937 173,500 Deer Flat (Lake Lowell) (Boise River) USBR A 1908 173,000 Arrowrock Dam and Reservoir (Boise River) USBR A 1915 286,600 Anderson Ranch Dam and Reservoir (Boise River) USBR A 1950 493,200 Lucky Peak Dam and Reservoir (Boise River) Corps of Engineers A 1957 293,100 Warm Springs Dam and Reservoir (Malheur River) Warmsprings ID A 1926 192,400 Agency Valley Dam and Beulah Reservoir USBR A 1935 59,000 (Malheur River)

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Total Mainstem/Tributary Facilities Current Owner Data Year Storage (Tributary Name) Or Operator Source Completed (acre-feet)

Willow Creek Dam and (Malheur) Reservoir Orchard ID A 1939 20,000 (Malheur River) Bully Creek Dam and Reservoir (Malheur River) USBR A 1963 31,600 Black Canyon Dam and Reservoir (Payette River) USBR B 1924 44,700 Lake Fork Dam and Reservoir (Payette River) Lake Fork ID A 1926 13,165 Deadwood Dam and Reservoir (Payette River) USBR A 1931 162,000 Payette Lakes System (Payette River) The Lake Reservoir Company A 1944 42,400 Cascade Dam and Reservoir (Payette River) USBR A 1948 703,200 Paddock Valley Reservoir (Payette River) Little Willow ID A 1949 25,100 Horsethief Reservoir (Payette River) Idaho Fish and Game A 1967 4,900 Crane Creek Dam and Reservoir (Weiser River) Crane Creek Admin Board A 1920 60,000 Lost Valley Dam and Reservoir (Weiser River) Lost Valley Reservoir Company A 1929 10,300 C. Ben Ross Dam and Reservoir (Weiser River) Little Weiser River ID A 1936 7,800 Mann Creek Dam and Reservoir (Weiser River) USBR A 1967 12,500 Unity Dam and Reservoir (Burnt River) USBR A 1938 25,500 Thief Valley Dam and Reservoir (Powder River) USBR A 1932 13,300 Mason Dam and Phillips Lake (Powder River) USBR A 1968 95,500 Total Upstream Storage from Brownlee Reservoir 10,318,437 Brownlee Idaho Power Company C 1958 1,420,000 Oxbow Idaho Power Company C 1961 57,500 Hells Canyon Idaho Power Company C 1969 170,000 Total Upstream Storage Including HCC 11,965,937 Notes: Mainstem facilities are list in the far left column in upstream to downstream order. Tributary facilites are indented and italicized. Tributary facilities are sorted by construction date within each major tributary and each major tributary is presented in downstream order. A. USBR 1998a B. USBR 1998b C. IPC unpublished data D. USGS 2000

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Table 3. List of water quality impaired segments for the Snake River that exceed Idaho state water quality standards or do not support their designated beneficial uses. (Source: IDEQ 1998, USEPA 2001).

River Segment Idaho §303 (d) Listed Pollutants Designated Beneficial Usesa

Snake River: RM 614.7 to 606.4 sediment, temperature cold water biota, salmonid spawning, primary (Shoshone Falls to Rock Creek) contact recreation Snake River: RM 606.4 to 599.1 sediment, temperature cold water biota, salmonid spawning, primary (Rock Creek to Cedar Draw Creek) contact recreation Snake River: RM 599.1 to 594.2 sediment, temperature cold water biota, salmonid spawning, primary (Cedar Draw Creek to Clear Lakes contact recreation Snake River: RM 594.2 to 591.5 sediment, temperature cold water biota, salmonid spawning, primary (Clear Lakes Bridge to Mud Creek) contact recreation Snake River: RM 591.5 to 591.4 sediment, temperature cold water biota, salmonid spawning, primary (Mud Creek to Deep Creek) contact recreation Snake River: RM 586.1 to 581.4 dissolved oxygen, flow alteration, cold water biota, salmonid spawning, primary (Upper Salmon Falls Reservoir) sediment contact recreation Snake River: RM 579.6 to 573.0 dissolved oxygen, flow alteration, cold water biota, salmonid spawning, primary (Lower Salmon Falls Reservoir) sediment contact recreation Snake River: RM 565.0 to 560.0 bacteria, dissolved oxygen, flow cold water biota, salmonid spawning, primary (Bliss Reservoir) alteration, NH3, sediment contact recreation Snake River: RM 559.9 to 556.6 nutrients, sediment, temperature cold water biota, salmonid spawning, primary (Cassia Gulch to Big Pilgrim Gulch) contact recreation Snake River: RM 556.6 to 544.9 sediment, temperature cold water biota, salmonid spawning, primary (Big Pilgrim Gulch to King Hill) contact recreation Snake River: RM 544.9 to 512.8 Sediment cold water biota, domestic water supply, (King Hill to C.J. Strike Reservoir at primary contact recreation, special resource Hwy 51 Bridge) water Snake River: RM 512.8 to 494.0 nutrients, pesticides cold water biota, primary contact recreation, (C.J. Strike Reservoir) special resource water Snake River: RM 494.0 to 471.0 Sediment cold water biota, domestic water supply, (C.J. Strike Reservoir to Castle primary contact recreation, special resource Creek) water Snake River: RM 471.0 to 457.7 Sediment cold water biota, domestic water supply, (Castle Creek to Swan Falls) primary contact recreation, special resource Snake River: RM 457.7 to 396.4 bacteria, dissolved oxygen, flow cold water biota, domestic water supply, (Swan Falls to Boise River inflow) alteration, nutrients, pH, sediment primary contact recreation, special resource Snake River: RM 396.4 to 351.6 bacteria, nutrients, pH, sediment cold water biota, primary contact recreation, (Boise River inflow to Weiser River domestic water supply inflow) Snake River: RM 351.6 to 347 bacteria, nutrients, pH, sediment cold water biota, primary contact recreation, (Weiser River inflow to Scott Creek domestic water supply inflow) Snake River: RM 347 to 285 dissolved oxygen, mercury, nutrients, cold water biota, primary contact recreation, (Brownlee Reservoir, Scott Creek to pH, sediment domestic water supply, special resource water Brownlee Dam) Snake River: RM 285 to 272.5 nutrients, sediment, pesticides cold water biota, primary contact recreation, (Oxbow Reservoir) domestic water supply, special resource water Snake River: RM 272.5 to 247 not listed cold water biota,primary contact recreation, (Hells Canyon Reservoir) domestic water supply,special resource water Snake River: RM 247 to 188 temperatureb cold water biota, primary contact recreation, (Hells Canyon Dam to Salmon domestic water supply, special resource water, River inflow) salmonid spawning

a All Snake River waters have the additional designated beneficial uses of: agricultural water supply, industrial water supply, wildlife habitats and aesthetics. b EPA addition to the 1998 Idaho 303 (d) list, January 2001

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Table 4. List of water quality impaired segments in the Snake River that exceed Oregon state water quality standards or do not support their designated beneficial uses.

River Segment Oregon §303 (d) Listed Pollutants Designated Beneficial Uses

Snake River: RM 409 to 395 mercury, temperature Public/private domestic water supply, (Upstream Snake River— industrial water supply, irrigation water, Owyhee Basin) livestock watering, salmonid rearing and spawning (trout), resident fish (warm water) and aquatic life, water contact recreation, wildlife and hunting, fishing, boating, aesthetics Snake River: RM 395 to 335 mercury, temperature Public/private domestic water supply, (Upstream Snake River to industrial water supply, irrigation water, Farewell Bend—Malheur livestock watering, salmonid rearing and Basin) spawning (trout), resident fish (warm water) and aquatic life, water contact recreation, wildlife and hunting, fishing, boating, aesthetics Snake River: RM 335 to 260 mercury, temperature public/private domestic water supply, (Brownlee Reservoir, Oxbow industrial water supply, irrigation water, Reservoir, Upper Half of livestock watering, salmonid rearing and Hells Canyon Reservoir— spawning, resident fish and aquatic life, Powder Basin) water contact recreation, wildlife and hunting, fishing, boating, aesthetics, hydropower Snake River: RM 260 to 188 mercury, temperature public/private domestic water supply, (Lower Half of Hells Canyon industrial water supply, irrigation water, Reservoir, Downstream livestock watering, salmonid rearing and Snake River—Grande spawning, resident fish and aquatic life, Ronde Basin) water contact recreation, wildlife and hunting, fishing, boating, aesthetics, anadromous fish passage, commercial navigation and transport

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Table 5. Within-location white sturgeon haplotype frequency and haplotype and sequence diversity in western North America. (Source: Anders and Powell 2002).

Region Location n Number of Haplotype Nucleotide code haplotypes diversity1 diversity2 Columbia CRE 20 11 0.86 0.72 LCR 20 8 0.81 0.67 TD 20 6 0.66 0.65 MCN 20 7 0.80 0.60 LKR 20 4 0.63 0.66 Snake LGO 20 7 0.75 0.55 HC 20 6 0.72 0.26 CJS 20 6 0.83 0.21 Kootenai KL 20 2 0.19 < 0.01 KR 20 2 0.01 0.04 Fraser LFR 20 9 0.85 1.14 NKO 20 4 0.76 0.16 Sacramento SAC 20 7 0.78 0.51

1 Haplotype diversity estimates according to Nei (1987, eqs. 8.5 and 8.12) 2 Nucleotide diversity estimates according to Nei and Tajima (1981).

124 Idaho Power Company Snake River White Sturgeon Conservation Plan

Table 6. Summary of effort and catch for white sturgeon sampled by Idaho Power Company in the Snake River between Shoshone Falls and the mouth of the Salmon River.

Hours Survey of CPUE Reach Year Gear Effort Catcha (fish/hr) Reference Shoshone–Upper Salmon 2001 Setline 10,378 232 0.02 Lepla et al. (2002) Gill net 29 19 0.65 Angling 36 0 0.00

Lower Salmon–Bliss 1992–93 Setline 6,198 3 0.0005 Lepla and Chandler (1995b) Gill Net 247 37 0.150 Angling 2 1 0.5

Bliss–C.J. Strike 1991–93 Setline 23,177 307 0.013 Lepla and Chandler (1995a) Gill net 703 450 0.64 Angling 13.2 18 1.36

C.J. Strike–Swan Falls 1994–96 Setline 33,747 340 0.010 Lepla and Chandler (1997) Gill net 448 267 0.595 Angling 129 47 0.363

Swan Falls–Brownlee 1996–97 Setline 16,752 32 0.002 Lepla et al. (2001) Gill net 268 12 0.048 Angling 18 1 0.055

Brownlee-Oxbow 1998 Setline 2,913 0 0.00 Lepla et al. (2001) Gill net 32 0 0.00

Oxbow–Hells Canyon 1998 Setline 2,690 4 0.001 Lepla et al. (2001) Gill net 39 0 0.00

Hells Canyon–Salmon R. 1997–00 Setline 27,658 843 0.03 Lepla et al. (2001) Angling 681 80 0.117

a Including recaptures

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Table 7. Abundance estimates for white sturgeon populations in Snake River reaches between Shoshone Falls and Lower Granite dams.

Number of Fish Densitye a Reach Year Sampled Population Estimate (95% CI) (fish/km) Reference

Shoshone Falls–Upper Salmon Falls 2001 224 777 >70 cm (574–1,201)b 18 Lepla et al. (2002) 1980–1981 14 — <6 Lukens (1981)

Upper Salmon Falls–Lower Salmon Falls 1980–1981 0 — — Lukens (1981)

Lower Salmon Falls–Bliss 1993 38 — — Lepla and Chandler (1995b) 1980–1981 11 — — Lukens (1981)

Bliss–C.J. Strike 2000 128 — — IPC (unpublished data) 1991–1993 669 2,662 > 80 cm (1,938−4,445) 30 Lepla and Chandler (1995a) 1979–1981 905 2,192 (1,479–4,276) 25 Cochnauer (1983)

C.J. Strike–Swan Falls 2001 138 — — IPC (unpublished data) 1994–1996 330 726 > 90 cm (473–1,565) 17 Lepla and Chandler (1997)

Swan Falls–Brownlee 1996–1997 42 155 > 70 cm (70–621)c 7c Lepla et al. (2001)

Brownlee–Oxbow 1998 0 — — Lepla et al. (2001)

Oxbow–Hells Canyon 1998 4 — — Lepla et al. (2001) 1992 7 — — ODFW (unpublished data)

Hells Canyon–Lower Granite 1997–2000d 1,423 3,625 > 70 cm (3,050–4,536) 17 Lepla et al. (2001) 1982–1984 331 3,955 23 Lukens (1985) 1972–1975 881 8,200–12,250 — Coon et al. (1977)

a Not including recaptures. b 95% artificially propagated fish. c Represents the segment of river from Swan Falls Dam (RM 458) to Walters Ferry (RM 444). d Population data combined from the 1997-2000 IPC and Nez Perce Tribe sturgeon surveys. e Density based on preliminary estimates of kilometers of usable habitat.

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Table 8. Mean relative weights based on fork length measurements for white sturgeon populations in the Snake River between Shoshone Falls and Lower Granite dams.

Mean Relative Mean Relative Mean Relative Weight All Fish Weight Weight River River Segment Year (N) Reservoir (N) (N) Reference Shoshone Falls–Upper 2001 100% (215) 88% (4) 100% (211) Lepla et al. (2002) Salmon Falls

1980–1981 104%(10) — 104%(10) Lukens (1981)

Lower Salmon Falls–Bliss 1992–1993 90% (31) 97%(8) 87% (22) Lepla and Chandler (1995b) 1980–1981 105%(11) — 105% (11) Lukens (1981)

Bliss–C.J. Strike 2000 96% (186) 98% (146) 88% (38) IPC (unpublished data) 1991–1993 100% (534) 101% (455) 91% (79) Lepla and Chandler (1995a)

1979–1981 91% (560)a — — Beamesderfer (1993) C.J. Strike–Swan Falls 2001 85% (148) — 85% (148) IPC (unpublished data) 1994–1996 88% (314) 83% (1) 88% (313) Lepla and Chandler (1997) Swan Falls–Brownlee 1996–1997 86% (37) 82% (10) 87% (27) Lepla et al. (2001)

1973 86% (1) — 86% (1) Reid et al. (1973)

Oxbow–Hells Canyon 1998 93% (2) 93% (2) — Lepla et al. (2001)

1992 93% (7) 93% (7) — ODFW (unpublished data) Hells Canyon– 1997–2000 88% (568) — 88% (568) Lepla et al. (2001) Salmon River Hells Canyon–Lower 1997–2000 88% (1247) 95% (269) 87% (978) Lepla et al. (2001) b Granite

1982–1984 89% (394) — 89% (394) Lukens (1985)

1972–1975 90% (600) — 90% (600) Coon et al. (1977)

a Relative weight based on total length as reported in Beamesderfer (1993). b Population data combined from IPC and Nez Perce Tribe sturgeon surveys.

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Table 9. Total annual mortality (A) and survival (S) estimates for white sturgeon sampled in the Snake River between Shoshone Falls and Lower Granite dams.

Survey Annual Annual Reach Year Ages Survival (S) Mortality (A) Reference Shoshone Falls–Upper 2001 8−13 0.88 0.12 Lepla et al. (2002) Salmon Falls

Bliss–C.J. Strike 2000 7−21 0.87 0.13 IPC (unpublished data) 1991−1993 12−22 0.87 0.13 Lepla and Chandler (1995a) 1979−1981 16−30 0.96 0.04 Cochnauer (1983)

C.J. Strike–Swan Falls 1994−1996 12−21 0.90 0.10 Lepla and Chandler (1997)

Hells Canyon–Salmon 1997−2000 6−12 0.87 0.13 Lepla et al. (2001) River

Hells Canyon–Lower 1982−1984 7−25 0.87 0.13 Lukens (1985) Granite 1972−1975 7−20 0.74 0.26 Coon et al. (1977)

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Table 10. Record of white sturgeon stocked by Idaho Department of Fish and Game and the Nez Perce Tribe in the Snake River.

Reach Year Stocked Year Class Number American Falls–Minidoka 1989 1988 1,152 1990 1988 100 1991 1990 206 1992 — 200 1995 1993 116 Total 1,774

Shoshone Falls–Upper Salmon Falls 1989 1988 3 1990 1988 172 1991 1990 531 1994 1993 352 1997 1995 150 Total 1,208

Lower Salmon Falls–Bliss 1989 1988 2,209 1991 1990 201 1994 1993 150 Total 2,560

Bliss–C.J. Strike 1989 1988 1,200 Total 1,200

Brownlee–Oxbow 1991 1990 43 1994 1993 70 Total 113

Oxbow–Hells Canyon 1991 1990 100 2000a N/A 50 Total 150

Boise River (tributary to the Swan Falls–Brownlee reach) 1991b N/A 30

1992b N/A 30 Total 60

a Fish stocked by the Nez Perce Tribe as part of preliminary evaluations on the feasibility of a “put-and-take” white sturgeon fishery in Hells Canyon Reservoir. b Fish not PIT-tagged.

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Table 11. Mean hourly weighted usable area (WUA) under Proposed Operations as a percent of WUA under Run-of-River Full Pool Operations hourly-WUA (HWUA) in the Hells Canyon Reach for white sturgeon life stages during the extreme low (1992), low (1994), medium (1995), high (1999), and extreme high (1997) flow years. The HWUA decreased metric is a mean of the 50–100% exceedence range of HWUA and the HWUA increased metric is a mean of the 0–50% exceedence range of HWUA. (Source: Chandler et al. 2002).

Hells Canyon Reach Mean % of Hourly RRFP WUA HWUA Decreased Metric HWUA Increased Metric 1992 1994 1995 1999 1997 1992 1994 1995 1999 1997 White Sturgeon Spawning 91.2 84.1 87.1 86.0 86.9 113.0 114.2 103.2 100.4 100.7

Incubation 82.8 72.1 95.2 96.7 97.5 134.3 129.7 104.2 106.8 113.2

Larvae 83.6 75.2 96.6 95.1 99.1 129.9 123.9 106.8 112.1 114.6

YOY 96.4 94.5 96.7 96.9 96.9 103.3 102.8 101.7 102.9 101.7

Juvenile 99.4 100.0 99.7 99.7 99.4 100.9 101.1 100.8 100.6 100.6

Adult 99.5 98.9 98.2 97.6 96.9 100.4 100.7 101.9 102.4 103.0

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Table 12. Cost estimates of IPC proposed mitigation measures for Snake River white sturgeon by hydroelectric project.

Mitigation Costs Assigned to Hydroelectric Projects Reach1 Measures Listed by Subsection2 SHF USF LSF BL CJS BR OX HC

SHF–USF 8.1.1 $488K *8.1.2 $420K 8.1.3 $311K 8.1.4 $17K USF–LSF 8.2.1 $183K 8.2.2 $17K LSF–BL 8.3.1 $253K 8.3.2 $17K BL–CJS 8.4.1 $552K 8.4.2 $17K CJS–SF 8.5.1 $578K *8.5.2 $100K *8.5.3 $774K 8.5.4 $477K 8.5.5 $17K 8.5.6 $20K SF–BR 8.6.1 $326K *8.6.3 $552K *8.6.4 $840K 8.6.5 $797K 8.6.6 $17K BR–OX 8.7.2 $163K 8.7.3 $17K OX–HC 8.7.2 $205K 8.7.3 $17K HC–LGR 8.8.2 $1.3M 8.8.3 $17K

3 Total Cost Estimate (millions) $1.23M $0.20M $0.27M $0.57M $1.96M $2.71M $0.22M $1.31M

1 Project Definition: SHF = Shoshone Falls, USF = Upper Salmon Falls, LSF = Lower Salmon Falls, BL = Bliss, CJS = C.J. Strike, SF = Swan Falls, BR = Brownlee, OX = Oxbow, and HC = Hells Canyon. 2 Proposed Measures: * indicates measure implementation contingent on feasibility and/or evaluation of study results of previous measures. 3 Total Cost Estimate: Sum cost of measures identified for white sturgeon by project over the duration of a new 30-year license. Because of the adaptive nature of the WSCP, actual costs may change depending on the effectiveness of proposed measures, results of feasibility analyses, or future information about sturgeon biology and management that may warrant additional measures. Costs associated with water quality measures are not included in the cost estimates.

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12. FIGURES

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Figure 1. Map of Snake River segments surveyed by Idaho Power Company for white sturgeon from Shoshone Falls downstream to the mouth of the Salmon River. The years indicate the time period during which each segment was surveyed.

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300

n=138 280 n=48 n=16 260

n=29 240

220

200 Total Length (cm)

180

160

140 Previtellogenic Early Vitellogenic Late Vitellogenic Ripe Figure 2. Range of total lengths, by reproductive category, for female white sturgeon sampled in the Snake River by Idaho Power Company, 1991−2000.

136 Idaho Power Company Snake River White Sturgeon Conservation Plan

spawning Bliss incubation yolk-sac larvae post-sac larvae (exogenous) age -0

spawning CJ Strike incubation yolk-sac larvae post-yolk sac larvae (exogenous) age -0

spawning

incubation Swan Falls yolk-sac larvae post- yolk sac larvae (exogenous) age -0 Reach

spawning Hells incubation Canyon yolk-sac larvae post- yolk sac larvae (exogenous) age -0

spawning Below Salmon R. incubation yolk-sac larvae post-yolk sac larvae (exogenous) age -0

01 07 13 19 25 31 06 12 18 24 30 06 12 18 24 30 05 11 17 23 29 05 11 17 23 29 26 04 10 16 22 28 03 09 15 21 27 03 09 15 21 27 02 08 14 20 26 02 08 14 20 26 Mar Apr May Jun Jul Figure 3. Estimated periods for spawning to age-0 life stages of Snake River white sturgeon. The occurrence of various life stage intervals was calculated based on the initiation of spawning using median Julian dates associated with lower (10 °C) and upper (18 °C) water temperature limits suitable for spawning in Snake River reaches, 1990–2000, and on embryonic development by Wang et al. (1985). The shaded portions of bars represent peak occurrence of the various life stages given peak spawning activity expected between 12 and 16 °C (based on egg collections in the Snake River) and subsequent embryonic development.

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30 Bliss-CJ Strike 20 n= 26 sturgeon

10

0

-10 Max Distance from Capture (%) Mean Movement (rm) -20 0-5 rm: 23 Reservoir 2.8 5-10 rm: 38 River 1.5 -30 >10 rm: 35

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920 30 CJ Strike-Swan Falls 20 n= 22 sturgeon

10

0

-10 Max Distance from Capture (%) Mean Movement (river miles) -20 0-5 rm: 77 Reservoir 0.7 5-10 rm: 14 River 0.5 -30 >10 rm: 09

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920

30 Swan Falls - Brownlee 20 n= 11 sturgeon

10

0

-10 Max Distance from Capture (%) Mean Movement (river miles) -20 0-5 rm: 45 Reservoir 1.3 5-10 rm: 27 River 0.4 -30 >10 rm: 27

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920

30 Oxbow - Hells Canyon 20 n = 3 sturgeon

10

0

MaximumInitial from Traveled Distance Capture (river miles) -10 Max Distance from Capture (%) Mean Movement (river miles) -20 0-5 rm: - Reservoir 4.0 5-10 rm: - River - -30 >10 rm: 100

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920 30 20 10 0 -10 -20 Hells Canyon - Salmon River -60 n = 22 sturgeon

Max Distance from Capture (%) Mean Movement (river miles) 0-5 rm: 68 Reservoir - 5-10 rm: 5 River 1.2 >10 rm: 27

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920 Days at Large Figure 4. Mean movement of and maximum recorded distance traveled by white sturgeon from their initial capture locations in Snake River reaches between Bliss Dam and the confluence with the Salmon River. Data from Idaho Power Company.

138 Idaho Power Company Snake River White Sturgeon Conservation Plan

Figure 5. Map of the Columbia River basin showing major dams on the mainstem Columbia and Snake rivers.

139 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 6. Average monthly natural flow and observed flow of the Snake River at Milner and the Boise River near Parma gauges. (Source: Miller et al. 2002).

140 Idaho Power Company Snake River White Sturgeon Conservation Plan

160 25 Shoshone Falls - Upper Salmon Falls Reach Flow (as measured at Buhl, Idaho) 30 1996 Temperature 20 Spawning Temperature (10-18 OC) 15 20

10 10 5

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 160 25 Bliss - C.J. Strike Reach Flow (as measured at King Hill, Idaho) 30 Temperature 1996 20 Spawning Temperature (10 - 18 OC) 15 20 C)

10 O 10 5

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 160 25 Swan Falls - Brownlee Reach Flow (measured at Murphy, ID) 30 1996 Temperature 20 Spawning Temperature (10 - 18 OC) 15 20 Mean Daily Temperature Temperature ( Mean Daily Mean Daily FlowMean Daily (kcfs) 10 10 5

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

160 25 Hells Canyon - Lower Granite Reach Flow (as measured at Anatone, WA) 140 Temperature 1996 20 120 Spawning Temperature (10 - 18 OC) 100 15 80 60 10 40 5 20 0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Date Figure 7. Mean daily flow and water temperature in four reaches of the Snake River during the white sturgeon spawning season in 1996.

141 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 8. Map of the Snake River from Shoshone Falls Dam to Upper Salmon Falls Dam.

142 Idaho Power Company Snake River White Sturgeon Conservation Plan

Figure 9. Annual contribution of water to the Snake River from springs along the north bank of the Snake River between Milner Dam and King Hill (from Clark et al. 1998). Numbers above bars represent percentages of annual streamflow.

143 Snake River White Sturgeon Conservation Plan Idaho Power Company

0.20 Upper Lower Shoshone Salmon Salmon Dam Falls Falls Falls Bliss C.J. Strike Swan Falls Brownlee Oxbow Hells Canyon Salmon River Reservoir

0.15 2001 1993 1991-93 1994-96 1996-97 1998 1998 1997-00 0.02 fish/hr 0.0005 0.013 fish/hr 0.01 fish/hr a) 0.002 fish/hr 0.00 0.001 fish/hr 0.03 fish/hr fish/hr fish/hr

0.10 free-flowing

Catch (fish/hour) Catch 0.05

0.00 600 580 560 540 520 500 480 460 440 420 400 380 360 340 320 300 280 260 240 220 200 River Mile 5000 Upper Lower Shoshone Salmon Salmon Dam Falls Falls Falls Bliss C.J. Strike Swan Falls Brownlee Oxbow Hells Canyon Salmon River Reservoir 4000

2001 1993 1991-93 1994-96 b) 1996-97 1998 1998 1997-00 10,378 hrs 6,198 23,177 hrs 33,747 hrs 16,752 hrs 2,913 2,690 hrs 27,658 hrs 3000 hrs hrs

free-flowing 2000 Hours of Effort Hours

1000

0 600 580 560 540 520 500 480 460 440 420 400 380 360 340 320 300 280 260 240 220 200 River Mile Figure 10. Catch rates of and hours of effort expended for white sturgeon sampled with setlines in the Snake River between Shoshone Falls and the confluence of the Salmon River.

144 Idaho Power Company Snake River White Sturgeon Conservation Plan

8 Upper Lower Shoshone Salmon Salmon Dam Falls Falls Falls Bliss C.J. Strike Swan Falls Brownlee Oxbow Hells Canyon Salmon River Reservoir

6 2001 1993 1991-93 1994-96 a) 1996-97 1998 1998 0.65 fish/hr 0.15 0.64 fish/hr 0.59 fish/hr 0.048 fish/hr 0.00 0.00 fish/hr fish/hr fish/hr

4 free-flowing

Catch(fish/hour) 2

0 600 580 560 540 520 500 480 460 440 420 400 380 360 340 320 300 280 260 240 220 200 River Mile 200 Upper Lower Shoshone Salmon Salmon Dam 180 Falls Falls Falls Bliss C.J. Strike Swan Falls Brownlee Oxbow Hells Canyon Salmon River Reservoir 160

140 2001 1993 1991-93 1994-96 b) 1996-97 1998 1998 29 hrs 247 hrs 703 hrs 448 hrs 268 hrs 32 hrs 39 hrs 120

100 free-flowing 80

Hours of of Effort Hours 60

40

20

0 600 580 560 540 520 500 480 460 440 420 400 380 360 340 320 300 280 260 240 220 200 River Mile Figure 11. Catch rates of and hours of effort expended for white sturgeon sampled with gill nets in the Snake River between Shoshone Falls and Hells Canyon Dam.

145 Snake River White Sturgeon Conservation Plan Idaho Power Company

50 92 cm 183 cm Shoshone Falls - Upper Salmon Falls 40 Wild a) 2001 Hatchery n = 203 20 19% 0.4% (wild) 8.4% (wild) 70.2% (hatchery) 2.0% (hatchery) 10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 Hatchery 92 cm 183 cm 40 b) Lower Salmon Falls - Bliss 1992 - 1993 30 71% (hatchery) 29% (hatchery) n = 3 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 92 cm 183 cm 40 Wild c) Bliss - C.J. Strike Hatchery 1991 - 1993 20 3.5% (wild) 40% 55% n = 260 1.5% (hatchery) 10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 Wild 92 cm 183 cm 40 C.J. Strike - Swan Falls Hatchery d) 1994 - 1996 20 6% (wild) 58.6% 35% n = 219 0.4% (hatchery) 10

Percent Catch Percent 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 Wild 92 cm 183 cm 40 Swan Falls - Brownlee e) 1996 - 1997 4% 26% 70% 20 n = 30

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 Wild 92 cm 183 cm Oxbow - Hells Canyon 40 Hatchery f) 1998 30 18% 15% 67% n = 4 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 50 Wild 92 cm 183 cm Hells Canyon - Lower Granite 40 g) 1997 - 2000 53% 29% 18% 20 n = 1,005 IPC & NPT (data combined) 10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Total Length (cm) Figure 12. Size distributions of white sturgeon sampled with setlines (adjusted for gear selectivity) in the Snake River between Shoshone Falls and Lower Granite Dam. Data below Hells Canyon Dam combined with the data from Nez Perce Tribe sturgeon surveys.

146 Idaho Power Company Snake River White Sturgeon Conservation Plan

50 Shoshone Falls - Upper Salmon Falls Wild a) 2001 40 Hatchery n = 19 30 92 cm 183 cm

20 11% (wild) 21% (hatchery) 6% (wild) 62% (hatchery) 10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 50 Lower Salmon Falls - Bliss Wild b) 40 Hatchery 1992 - 1993 n = 34 30 92 cm 183 cm 5% (wild) 5% (wild) 20 85% (hatchery) 5% (hatchery)

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 50 Bliss - C.J. Strike Wild c) 40 Hatchery 1991 - 1993 n = 396 30 92 cm 183 cm 8% (wild) 71% (wild) 13% 20 7% (hatchery) 1% (hatchery)

10 Percent Catch

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 50 C.J. Strike - Swan Falls Wild d) 40 Hatchery 1994 - 1996 n = 166 30 92 cm 183 cm 16.4% (wild) 68% 15% 20 0.6% (hatchery)

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 50 Swan Falls - Brownlee Wild 40 e) 1996 - 1997 n = 12 30 92 cm 183 cm 79% 21% 20

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Total Length (cm) Figure 13. Size distributions of white sturgeon sampled with gill nets (adjusted for gear selectivity) in the Snake River between Shoshone Falls and Brownlee Dam.

147 Snake River White Sturgeon Conservation Plan Idaho Power Company

100

Shoshone - Upper Salmon Falls: 2001 90 Wt = 1.30E-06 x TL 3.28 n = 218 Bliss - C.J. Strike: 1991-1993 Wt = 1.27E-06 x TL 3.29 80 n = 540 C.J. Strike - Swan Falls: 1994-1996 Wt = 1.57E-06 x TL 3.23 70 n = 315 Swan Falls - Brownlee: 1996-1997 Wt = 2.26E-06 x TL 3.16 60 n = 35 Hells Canyon - Lower Granite: 1997-2000 Wt = 3.42E-06 x TL 3.09 n = 1,257 50

Weight (kg) 40

30

20

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260

Total Length (cm) Figure 14. Length–weight relationships for white sturgeon in Snake River reaches between Shoshone Falls and Lower Granite Dam.

148 Idaho Power Company Snake River White Sturgeon Conservation Plan

20 a) 18 1993 Year Class 1990 Year Class Mean = 9.6 cm TL 16 1988 Year Class n= 38 Mean = 8.9 cm TL 14 n= 34 Mean = 8.7 cm TL 12 n= 19

10

8

6

4

2

Annual In-River Increasein TL) Length (cm In-River Annual 0 0 2 4 6 8 10 12 14 6

1993 Year Class b) 1990 Year Class 5 Mean = 2.21 kg 1988 Year Class n= 19

4

3 Mean = 1.17 kg Mean = 0.88 kg n= 34 n= 38

2

1 Annual In-RiverAnnual IncreaseWeight in (kg)

0 02468101214

Age (years) Figure 15. Annual in-river growth (length and weight) of hatchery-propagated white sturgeon in the Snake River between Shoshone Falls and Upper Salmon Falls Dam. Data obtained from Lepla et al. (2002).

149 Snake River White Sturgeon Conservation Plan Idaho Power Company

300 280 260 240 220 200

180 Shoshone Falls - Upper Salmon Falls n =91 160 Bliss - C.J. Strike 140 Linfinity: 334, K: 0.038, To: -1.593 n = 180 120 C.J. Strike - Swan Falls

Linfinity: 309, K: 0.047, To: -0.448

Total Length(cm) 100 n = 62 80 Swan Falls - Brownlee Linfinity: 290, K: 0.046, T : -1.117 60 o n = 21 40 Hells Canyon - Lower Granite (Tuell and Everett 2001)

20 Linfinity: 296, K: 0.047, To: -0.659 n = 247 0 0 5 10 15 20 25 30 35 40 45 50

Age (years) Figure 16. Von Bertalanffy growth (VBG) lines and mean total length (Shoshone Falls–Upper Salmon Falls reach) for white sturgeon in the Snake River between Shoshone Falls and Lower Granite Dam.

150 Idaho Power Company Snake River White Sturgeon Conservation Plan

100 90 Lukens (1981) a) 1979 - 1981 80 n = 14 70 Wild 60 50 40 30 20 10 2D Graph 2 0 < 92 cm 92 - 183 cm > 183 cm 100 Lepla et al. (2002) 90 b) 2001 80 a) Setline Wild n = 203 70 Hatchery 60 50 40 30 Percent Catch 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 Lepla et al. (2002) 90 c) 2001 Wild 80 Gill Net Hatchery n = 19 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm

Figure 17. Size composition of white sturgeon sampled in the Snake River between Shoshone Falls and Upper Salmon Falls Dam during the 1980–1981 period (Lukens 1981) and in 2001 (Lepla et al. 2002).

151 Snake River White Sturgeon Conservation Plan Idaho Power Company

40 Kimberly 35 March - June 1923 - 00 30

25

20

15

10 1,970 cfs (median)

5

0 0 102030405060708090100

40 Flow (kcfs) Buhl 35 March - June 1946 - 00 30

25

20

15

10 4,349 cfs (median)

5

0 0 102030405060708090100 Percent Exceedence

Figure 18. Percentage of exceedence of river flow for the periods of record during spawning, incubation, and larval life stages of development (March–June) for Snake River white sturgeon between Shoshone Falls and Upper Salmon Falls Dam. River flows measured at USGS flow gauges in the Snake River near Kimberly and Buhl, Idaho.

152 Idaho Power Company Snake River White Sturgeon Conservation Plan

Figure 19. Map of the Snake River from Upper Salmon Falls Plant B downstream to Bliss Dam.

153 Snake River White Sturgeon Conservation Plan Idaho Power Company

100 a) Lukens (1981) 80 1979-1981 Wild n = 11 60

40

20

0 < 92 cm 92 - 183 cm > 183 cm 100 Lepla and Chandler (1995b) 80 b) 1992-1993 Setline 60 Hatchery n = 3 40

20

0 < 92 cm 92 - 183 cm > 183 cm 100 Lepla and Chandler (1995b) 80 c) 1992-1993 Gill Net 60 Wild n = 34 Hatchery 40

20 Percent Catch

0 < 92 cm 92 - 183 cm > 183 cm 100 IPC (unpublished data) 80 d) 1996 Setline 60 Wild n = 9 Hatchery 40

20

0 < 92 cm 92 - 183 cm > 183 cm 100 IPC (unpublished data) 80 e)LSF 96 SL Wild 1996 LSF 96 SL HATCH Wild Gill Net 60 Hatchery n = 25 Unknown 40

20

0 < 92 cm 92 - 183 cm > 183 cm Size Groups (TL) Figure 20. Size composition of white sturgeon sampled in the Lower Salmon Falls– Bliss reach.

154 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Spawning

1992 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

50 50 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

50 50 0 20406080100 Percent time exceeded 1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 10/1/95 11/1/95 12/1/95

1997 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

50 50 0 20406080100 Percent time exceeded 1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 10/1/97 11/1/97 12/1/97 Figure 21. Minimum daily Weighted Usable Area (MDW) expressed as a percent of run-of-river WUA (left) and percent time exceeded for hourly WUA (HW) as a percent of run-of-river WUA (right) for white sturgeon spawning, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000).

155 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Juvenile

1992 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of % WUA river' Hourly Minimum daily % of 'run of % WUA river' daily Minimum

50 50 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of % WUA river' Hourly Minimum daily % of 'run of % WUA river' daily Minimum

50 50 0 20406080100 Percent time exceeded 1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 10/1/95 11/1/95 12/1/95

1997 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of % WUA river' Hourly Minimum daily % of 'run of % WUA river' daily Minimum

50 50 0 20406080100 Percent time exceeded 1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 10/1/97 11/1/97 12/1/97 Figure 22. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for juvenile white sturgeon, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000).

156 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Adult

1992 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of river' WUA Minimum % daily of 'run of river' WUA

50 50 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

90 90

80 80

70 70

60 WUA river' 'run of %Hourly of 60 Minimum % daily of 'run of river' WUA

50 50 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

90 90

80 80

70 70

60 60 Hourly % of 'run of river' WUA Minimum % daily of 'run of river' WUA

50 50 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 23. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for adult white sturgeon, Lower Salmon Falls Reach, 1992, 1995, and 1997. (Source: Brink 2000).

157 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 24. Map of the Bliss–C.J. Strike reach of the Snake River.

158 Idaho Power Company Snake River White Sturgeon Conservation Plan

14 Sturgeon 92-183 cm TL Mean annual growth = 6.2 cm TL n= 36 12 Sturgeon >183 cm TL Mean annual growth = 3.9 cm TL n = 21 10

8

6

Annual GrowthAnnual (cm TL) 4

2

0 0 500 1000 1500 2000 2500 3000 3500

Days at Large Figure 25. Annual growth of recaptured white sturgeon in the Bliss–C.J. Strike reach of the Snake River.

159 Snake River White Sturgeon Conservation Plan Idaho Power Company

100 Cochnauer (1983) 90 a) 80 1979 - 1981 n = 667 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 b) Lepla and Chandler (1995a) 1991 - 1993 80 Wild Setline 70 Hatchery n = 260 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 c) Lepla and Chandler (1995a) Percent Catch Percent 80 1991 - 1993 Wild Gill Net 70 Hatchery n = 396 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 d) IPC (unpublished data) 80 Wild 2000 70 Hatch Gill Net n = 128 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm Size Group (TL) Figure 26. Size composition of white sturgeon sampled in the Bliss–C.J. Strike reach of the Snake River.

160 Idaho Power Company Snake River White Sturgeon Conservation Plan

20000

18000

Bliss Dam On-line (1950) 16000

14000 Median annual flow as measured at King Hill, ID from1909-2000

12000

10000

8000

Annual FlowAnnual (cfs) 6000

4000

2000

0 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year Figure 27. Annual flow in the Snake River as measured below Bliss Dam at King Hill, Idaho.

161 Snake River White Sturgeon Conservation Plan Idaho Power Company

30 Bliss - C.J. Strike 2000 n = 183 25

20

15

Number of Fish Number 10

5

0 2000 1995 1990 1985 1980 1975 1970 1965

Year Figure 28. Estimated age distribution of white sturgeon collected in the Bliss– C.J. Strike reach of the Snake River during 2000.

162 Idaho Power Company Snake River White Sturgeon Conservation Plan

25000 25000 1988 1989

20000 20000

15000 15000

10000 10000

5000 5000

0 0 Mar Apr May Jun Mar Apr May Jun 25000 25000 1990 1992 20000 20000

15000 15000

10000 10000 Hourly Flow (cfs)Hourly 5000 5000

0 0 Mar Apr May Jun Mar Apr May Jun

25000 25000 1993 1994

20000 20000

15000 15000

10000 10000

5000 5000

0 0 Mar Apr May Jun Mar Apr May Jun

Date Figure 29. Hourly river flows below Bliss Dam during the white sturgeon spawning season for 1988 through 1994.

163 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Spawning

1992 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100

1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 Percent time exceeded 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 30. Minimum daily Weighted Usable Area (MDW) expressed as a percent of run-of-river WUA (left) and percent time exceeded for hourly WUA (HW) as a percent of run-of-river WUA (right) for white sturgeon spawning, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

164 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Incubation

1992 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % of daily river' WUAMinimum

0 0 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % of daily river' WUAMinimum

0 0 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % of daily river' WUAMinimum

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 31. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for white sturgeon incubating eggs, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

165 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Larvae

1992 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % ofHourly 'run % of river' WUA Minimum daily % of 'run % daily of river' WUAMinimum

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 32. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for white sturgeon larvae, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

166 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Young-of-Year

1992 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA of river' Hourly % of 'run Minimum daily % of 'run of river' WUA of river' Minimum daily % of 'run

0 0 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA of river' Hourly % of 'run Minimum daily % of 'run of river' WUA of river' Minimum daily % of 'run

0 0 0 20406080100 Percent time exceeded 1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA of river' Hourly % of 'run Minimum daily % of 'run of river' WUA of river' Minimum daily % of 'run

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 33. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for young-of-year white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

167 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Juvenile

1992 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

0 0 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

0 0 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 34. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for juvenile white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

168 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Adult

1992 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

0 0 0 20406080100 Percent time exceeded 1/1/92 2/1/92 3/1/92 4/1/92 5/1/92 6/1/92 7/1/92 8/1/92 9/1/92 10/1/92 11/1/92 12/1/92

1995 100 100

80 80

60 60

40 40

20 Hourly % of 'run of river' WUA 20 Minimum daily % of 'run of river' WUA

0 0 0 20406080100

1/1/95 2/1/95 3/1/95 4/1/95 5/1/95 6/1/95 7/1/95 8/1/95 9/1/95 Percent time exceeded 10/1/95 11/1/95 12/1/95

1997 100 100

80 80

60 60

40 40

20 20 Hourly % of 'run of river' WUA Minimum daily % of 'run of river' WUA

0 0 0 20406080100

1/1/97 2/1/97 3/1/97 4/1/97 5/1/97 6/1/97 7/1/97 8/1/97 9/1/97 Percent time exceeded 10/1/97 11/1/97 12/1/97 Figure 35. Minimum daily Weighted Usable Area expressed as a percentage of run-of-river WUA (left) and a percentage of time exceeded curve for hourly WUA (HW) as a percentage of run-of-river WUA (right) for adult white sturgeon, in Bliss Reach 1992, 1995, and 1997, representing dry, medium, and wet years respectively. (Source: Brink and Chandler 2000).

169 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 36. Map of the C.J. Strike–Swan Falls reach of the Snake River from C.J. Strike Dam to Swan Falls Dam.

170 Idaho Power Company Snake River White Sturgeon Conservation Plan

80

70 a) IDFG 1989 60 Angling n = 181 50

40

30

20

10

0 < 92 cm 92 - 183 cm > 183 cm 80 Lepla and Chandler (1997) 70 b) 1994 - 1996 Setline 60 n = 218

50

40

30

Percent Catch Percent 20

10

0 < 92 cm 92 - 183 cm > 183 cm 80 IPC (unpublished data) 70 c) 2001 Setline 60 n = 135

50

40

30

20

10

0 < 92 cm 92 - 183 cm > 183 cm

Size Group (TL) Figure 37. Size composition of white sturgeon sampled in the C.J. Strike–Swan Falls reach of the Snake River.

171 Snake River White Sturgeon Conservation Plan Idaho Power Company

200,000 Spawning Area– CJ Strike Tailrace 50 WUA

% Area

) 40

2 150,000

t

f

( 30

A

U 100,000

W 20

50,000 10

0 `0 AREA TOTAL OF PERCENT 0 5,000 10,000 15,000 20,000 25,000

DISCHARGE (cfs) Figure 38. Weighted Usable Area and WUA (ft2) as a percentage of total area for white sturgeon spawning in the tailrace of C.J. Strike Dam. (Source: Chandler and Lepla 1997).

172 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Spawning C.J. Strike Reach 1992

1

0.8

0.6

0.4

Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum 0.2

0 r r r r r r r r y y y y y y y y n n n n n n n p p p p p p p p a a a a a a a a u u u u u u u A A A A A A A A J J J J J J J ------M -M -M -M -M -M -M -M ------1 5 9 3 7 1 5 9 3 7 1 5 9 3 7 1 4 8 2 6 0 4 8 0 0 0 1 1 2 2 2 0 0 1 1 1 2 2 3 0 0 1 1 2 2 2 Date

1

0.8

0.6

0.4

0.2 Minimum Daily Percentof Mean Flow WUA

0 0 20406080100 Percent of Time Exceeded Figure 39. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997).

173 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Spawning C.J. Strike Reach 1995

1

0.8

0.6

0.4

Minimum Daily Mean PercentMinimum of WUA Flow 0.2

0 r r r r r r r r y y y y y y y y n n n n n n n p p p p p p p p a a a a a a a a u u u u u u u A A A A A A A A J J J J J J J ------M -M -M -M -M -M -M -M ------1 5 9 3 7 1 5 9 3 7 1 5 9 3 7 1 4 8 2 6 0 4 8 0 0 0 1 1 2 2 2 0 0 1 1 1 2 2 3 0 0 1 1 2 2 2 Date

1

0.8

0.6

0.4

0.2 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0 0 20406080100 Percent of Time Exceeded Figure 40. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997).

174 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Spawning C.J. Strike Reach 1986

1

0.8

0.6

0.4

Minimum Daily Percent Mean of Flow WUA 0.2

0 r r r r r r r r y y y y y y y y n n n n n n n p p p p p p p p a a a a a a a a u u u u u u u A A A A A A A A J J J J J J J ------M -M -M -M -M -M -M -M ------1 5 9 3 7 1 5 9 3 7 1 5 9 3 7 1 4 8 2 6 0 4 8 0 0 0 1 1 2 2 2 0 0 1 1 1 2 2 3 0 0 1 1 2 2 2 Date

1

0.8

0.6

0.4

0.2 MinimumDaily Percent Mean of Flow WUA

0 0 20406080100 Percent of Time Exceeded Figure 41. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon spawning period, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997).

175 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Young-of-the-Year C.J. Strike Reach 1992

1

0.9

0.8

0.7

Minumum Daily Percent ofMean 0.6 Flow WUA

0.5 r r r y y y l l l t t t v v v c c p p p n n n u u u g g p p p c c c a a a u u u J J J u u e e e o o o e e A A A M M M J J J - - - A A S S S O O O N N N D D ------9 0 1 ------1 2 3 4 5 6 6 7 8 0 2 3 1 2 2 3 4 5 6 7 7 8 9 0 1 0 1 2 0 1 2 0 1 2 1 2 0 1 2 0 1 2 0 1 2 1 2 Date

1

0.9

0.8

0.7

0.6 Minumum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minumum

0.5 0 20406080100 Percent of Time Exceeded Figure 42. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997).

176 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Young-of-the-Year C.J. Strike Reach 1995

1

0.9

0.8

0.7

0.6 Minumum Daily Percent Mean of Flow WUA

0.5 r r r y y y l l l g g p p t t v v v c c p p p n n n p ct c c a a a u Ju Ju Ju u u e e e o o e e A A A M M Ju J Ju - - - A A S S S O O O N No N D D - - - -M - - - - - 9 0 1 ------1 2 3 4 5 6 6 7 8 2 3 1 2 2 3 4 5 6 7 7 8 9 0 1 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7

0.6 Minumum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minumum

0.5 0 20406080100 Percent of Time Exceeded Figure 43. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997).

177 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Young-of-the-Year C.J. Strike Reach 1986

1

0.9

0.8

0.7

Minumum Daily Percent of Mean WUA of Percent Flow Daily Minumum 0.6

0.5 r r r y y y l l l t t t v v v c c p p p n n n u u u g g p p p c c c a a a u u u J J J u u e e e o o o e e A A A M M M J J J - - - A A S S S O O O N N N D D ------9 0 1 ------1 2 3 4 5 6 6 7 8 0 2 3 1 2 2 3 4 5 6 7 7 8 9 0 1 0 1 2 0 1 2 0 1 2 1 2 0 1 2 0 1 2 0 1 2 1 2 Date

1

0.9

0.8

0.7

0.6 Minumum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minumum

0.5 0 20406080100 Percent of Time Exceeded Figure 44. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon young-of-year, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997).

178 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Juvenile C.J. Strike Reach 1992

1

0.9

0.8

0.7

0.6 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0.5

r r r r r y y l l t t v v c c n n n b a a a p p n n u u g g p p c c a a a e a a u u J J u u e e o o e e J J J F M M M A A J J - - A A S S O O N N D D ------M -M - - 4 9 ------1 6 1 5 1 6 1 5 0 5 0 4 9 1 2 3 8 2 7 2 7 1 6 1 6 0 1 3 1 0 1 3 1 3 1 3 1 2 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7

0.6

Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum 0.5

0.4 0 20406080100 Percent of Time Exceeded Figure 45. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997).

179 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Juvenile C.J. Strike Reach 1995

1

0.9

0.8

0.7

0.6 Minimum Daily Percent of Mean Flow WUA

0.5

r r r r l l t t n n n b y y y n n u u g g p p c c v v c c a a a e a a p p a a a u u J J u u e e o o e e J J J F M M A A J J - - A A S S O O N N D D ------M -M -M - - 5 0 ------1 6 1 5 2 7 1 6 1 6 1 5 0 1 3 4 9 3 8 3 8 2 7 2 7 1 3 1 1 1 1 3 1 3 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7

0.6

Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum 0.5

0.4 0 20406080100 Percent of Time Exceeded Figure 46. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997).

180 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Juvenile C.J. Strike Reach 1986

1

0.9

0.8

0.7

0.6 Minimum Daily Percent of Mean Flow WUA

0.5

r r r r y y y l l t t v v c c n n n b a a p p n n u u g g p p c c a a a e a a a u u J J u u e e o o e e J J J F M M A A J J - - A A S S O O N N D D ------M -M -M - - 5 0 ------1 6 1 5 2 7 1 6 1 6 1 5 0 1 3 4 9 3 8 3 8 2 7 2 7 0 1 3 1 0 1 0 1 0 1 3 1 3 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7

0.6

Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum 0.5

0.4 0 20406080100 Percent of Time Exceeded Figure 47. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon juveniles, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997).

181 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Adult C.J. Strike Reach 1992

1

0.9

0.8 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0.7

n n n b r r r r r r r r r r r r r r r r r r r r r a a a e a a a a a a a a a a a a a a a a a a a a a J J J - - - -F -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M -M 1 6 1 5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 3 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Date

1

0.9

0.8

0.7 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0.6 0 20406080100 Percent of Time Exceeded Figure 48. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1992. (Source: Chandler and Lepla 1997).

182 Idaho Power Company Snake River White Sturgeon Conservation Plan

White Sturgeon Adult C.J. Strike Reach 1995

1

0.9

0.8 Minimum Daily Percent Mean of Flow WUA 0.7

b r r r r y y y l l g g p p t t v v c c n n n a a p p n n u u c c a a a e a a a u u J J u u e e o o e e J J J F M M A A J J - - A A S S O O N N D D ------M -M -M - - 5 0 ------1 6 1 5 2 7 1 6 1 6 1 5 0 1 3 4 9 3 8 3 8 2 7 2 7 1 3 1 1 1 1 3 1 3 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0.6 0 20406080100 Percent of Time Exceeded Figure 49. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1995. (Source: Chandler and Lepla 1997).

183 Snake River White Sturgeon Conservation Plan Idaho Power Company

White Sturgeon Adult C.J. Strike Reach 1986

1

0.9

0.8 MinimumDaily Percentof Mean Flow WUA

0.7

r r r r y y y l l t t v v c c n n n b a a p p n n u u g g p p c c a a a e a a a u u J J u u e e o o e e J J J F M M A A J J - - A A S S O O N N D D ------M -M -M - - 5 0 ------1 6 1 5 2 7 1 6 1 6 1 5 0 1 3 4 9 3 8 3 8 2 7 2 7 0 1 3 1 0 1 0 1 0 1 3 1 3 1 2 1 2 1 2 1 2 1 2 Date

1

0.9

0.8

0.7 Minimum Daily Percent of Mean Flow WUA Flow Mean of Percent Daily Minimum

0.6 0 20406080100 Percent of Time Exceeded Figure 50. (Top) Daily Weighted Usable Area (WUA) expressed as minimum daily percentage of mean flow WUA and (Bottom) percentage exceeded curve for minimum daily percentage of mean flow [i.e., run-of-river] WUA for the white sturgeon adults, C.J. Strike Reach, 1986. (Source: Chandler and Lepla 1997).

184 Idaho Power Company Snake River White Sturgeon Conservation Plan

20 C.J. Strike - Swan Falls 1994 - 1996 a) n = 219

15 Wild Hatchery 92 cm 183 cm

6% (wild) 58.6% 35% 10 0.4% (hatchery)

5

0 0 20 40 60 80 100 120 140 160 180 200 220 240

20 C.J. Strike - Swan Falls C.J.2001 Strike - Swan Falls Percent Catch 2001n = 135 b) n = 135 15 92 cm 183 cm 92 cm 183 cm

8%8% 69% 69% 23%23% 10

5

0 0 20 40 60 80 100 120 140 160 180 200 220 240

Total Length (cm TL) Figure 51. Size distributions of white sturgeon sampled with setlines in the C.J. Strike– Swan Falls reach of the Snake River during 1994–1996 and in 2001.

185 Snake River White Sturgeon Conservation Plan Idaho Power Company

100 100 1996 1996 80 80

60 60

40 40

20 20

0 0 Mar Apr May Jun 0 20406080100 100 100 1997 1997 80 80

60 60

40 40

20 20

0 0 Mar Apr May Jun 0 20406080100 100 100 1998 1998 80 80

60 of 'run river'DailyWUA % 60

40 40 Minimum Daily % of 'run of river' WUA ofMinimum 'run of river' Daily % 20 20

0 0 Mar Apr May Jun 020406080100

100 100 19991999 1999 80 80

60 60

40 40

20 20

0 0 Mar Apr May Jun 0 20406080100 Date Percent time exceeded Figure 52. Daily weighted usable area (WUA) expressed as minimum daily percentage of run-of-river WUA and percentage-exceeded curve for minimum daily percentage of run-of-river WUA for the white sturgeon spawning periods during 1996 to 1999 below C.J. Strike Dam.

186 Idaho Power Company Snake River White Sturgeon Conservation Plan

Figure 53. Map of the Swan Falls–Brownlee reach of the Snake River.

187 Snake River White Sturgeon Conservation Plan Idaho Power Company

100 IDFG 90 a) 80 1986 - 1987 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 IDFG b) 80 1989 70 Angling n = 66 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 Lepla et al. (2001)

Percent Catch Percent c) 80 1996 - 1997 70 Gill Net 60 n = 12 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 Lepla et al. (2001) 80 d) 1996 - 1997 70 Setline 60 n = 30 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm Size Group (TL) Figure 54. Size composition of white sturgeon sampled in the Swan Falls–Brownlee reach of the Snake River.

188 Idaho Power Company Snake River White Sturgeon Conservation Plan

Brownlee Reservoir dissolved oxygen profile, August 3, 1992

2050

2000

1950 levation (ft) levation E 1900

1850

1800 285 290 295 300 305 310 315 320 325 330 335 River Mile

Brownlee Reservoir dissolved oxygen profile, August 9 - 10, 1995

2050

2000

1950 levation (ft) levation E 1900

1850

1800 285 290 295 300 305 310 315 320 325 330 335 River Mile

Brownlee Reservoir dissolved oxygen profile, August 6, 1997

2050

2000

1950 levation (ft) levation E 1900

1850

1800 285 290 295 300 305 310 315 320 325 330 335 River Mile Figure 55. Dissolved oxygen (DO) isopleths for Brownlee Reservoir representing low (1992), medium (1995) and high (1997) hydrologic years. (Source: Myers et al. 2001).

189 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 56. Map of the Brownlee–Hells Canyon reach of the Snake River.

190 Idaho Power Company Snake River White Sturgeon Conservation Plan

100 ODFW (unpublished data) 90 Wild a) 1992 Hatchery Setline n = 7 80

70

60

50

40

30

20

10

0 < 92 cm 92 - 183 cm > 183 cm

100 Lepla et al. (2001) Percent Catch Percent 90 Wild 1998 Hatchery b) Setline 80 n = 4

70

60

50

40

30

20

10

0 < 92 cm 92 - 183 cm > 183 cm

Size Group (TL) Figure 57. Size composition of white sturgeon sampled in the Oxbow–Hells Canyon reach of the Snake River.

191 Snake River White Sturgeon Conservation Plan Idaho Power Company

140

120

) 100

80 x 1000

2

60

WUA (m WUA 40

20

0 0 5000 10000 15000 20000 25000

100

90

80

70

60

50

40 Total (%) Area 30

20

10

0 0 5000 10000 15000 20000 25000

Q (cfs) Figure 58. White sturgeon spawning habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow Bypass (transects 1−8). (Source: Myers and Chandler 2001).

192 Idaho Power Company Snake River White Sturgeon Conservation Plan

32 30 28 26 24

) 22 20 18 x 1000

2 16 14 12 10 WUA (m WUA 8 6 4 2 0 0 5000 10000 15000 20000 25000

100

90

80

70

60

50

40 Total Area (%) Total Area 30

20

10

0 0 5000 10000 15000 20000 25000

Q (cfs) Figure 59. White sturgeon incubation habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow Bypass (transects 1– 8). (Source: Myers and Chandler 2001).

193 Snake River White Sturgeon Conservation Plan Idaho Power Company

100

80 )

60 x 1000 2

40 WUA (m WUA

20

0 10000 15000 20000 25000 30000 35000 40000

100

90

80

70

60

50

40 Total Area (%) Total Area 30

20

10

0 10000 15000 20000 25000 30000 35000 40000

Q (cfs) Figure 60. White sturgeon spawning habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow tailwater (transects 9–11). (Source: Myers and Chandler 2001).

194 Idaho Power Company Snake River White Sturgeon Conservation Plan

40

30 ) x 1000 x

2 20 WUA (m WUA 10

0 10000 15000 20000 25000 30000 35000 40000

100

90

80

70

60

50

40 Total Area (%) Area Total 30

20

10

0 10000 15000 20000 25000 30000 35000 40000

Q (cfs) Figure 61. White sturgeon incubation habitat weighted usable area (top graph) and percentage of total area (bottom graph) in the Oxbow tailwater (transects 9–11). (Source: Myers and Chandler 2001).

195 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 62. Map of the Hells Canyon–Lower Granite reach of the Snake River.

196 Idaho Power Company Snake River White Sturgeon Conservation Plan

100 Coon et al. (1977) 90 a) 1972-75 80 n = 617 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 Lukens (1985) b) 80 1982 - 1984 n = 407 70 60 50 40

Percent Catch 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 Lepla et al. 2001 c) 1997 - 2000 80 S etlin e 70 n = 1,005 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm Size Group (TL) Figure 63. Size composition of white sturgeon sampled in the Hells Canyon–Lower Granite reach of the Snake River.

197 Snake River White Sturgeon Conservation Plan Idaho Power Company

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198 Idaho Power Company Snake River White Sturgeon Conservation Plan

Figure 64. Schematic diagram of IPC proposed mitigation measures for Snake River white sturgeon between Shoshone Falls and C.J. Strike dams.

199 Snake River White Sturgeon Conservation Plan Idaho Power Company

Figure 65. Schematic diagram of IPC proposed mitigation measures for Snake River white sturgeon between C.J. Strike and Lower Granite dams.

200 Idaho Power Company Snake River White Sturgeon Conservation Plan

13. APPENDICES

201 Snake River White Sturgeon Conservation Plan Idaho Power Company

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202 Idaho Power Company Snake River White Sturgeon Conservation Plan

Appendix 1. Population Viability Model for Snake River White Sturgeon.

203 Snake River White Sturgeon Conservation Plan Idaho Power Company

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204

Population Viability Model for Snake River White Sturgeon

Henriette Jager Oak Ridge National Laboratory

Ken Lepla, James Chandler, Ralph Myers Aquatic Section, Environmental Affairs, Idaho Power Company

Webb Van Winkle Environmental Consultant, Boise

Annett Sullivan, Mark Bevelhimer Oak Ridge National Laboratory

Technical Report Appendix E.3.1-6 Chapter 3 December 2001 Hells Canyon Complex FERC No. 1971

Snake River White Sturgeon Conservation Plan Idaho Power Company

ABSTRACT

This report describes Idaho Power Company’s population viability analysis (PVA) for white sturgeon in the middle Snake River. The PVA process has been valuable in a number of ways. First, it provided white sturgeon investigators with a framework around which to organize existing information from the scientific literature and from researchers working in the Snake and Columbia rivers. Second, developing the PVA model to describe the relationships between river habitat and white sturgeon dynamics improved our intuition about these relationships. Third, we used the model to highlight key factors limiting white sturgeon recruitment in each river segment. Two of the limiting factors identified by this analysis were poor water quality in Brownlee Reservoir and poor larval export from shorter river segments. Finally, the model predicted that persistence beyond the next 200 years is less likely in some river segments than in others under current operations. While the model can stimulate discussion and identify unanticipated relationships, other factors that are not included or are not sufficiently quantified to give precise quantitative predictions may be operating. Therefore, we recommend continued studies that quantify the parameters needed in PVA model relationships or directly test the importance of these factors affecting white sturgeon recruitment.

Page 1 Idaho Power Company Snake River White Sturgeon Conservation Plan

1. INTRODUCTION

The white sturgeon (Acipenser transmontanus) is a large, long-lived and late-maturing fish species that historically migrated between the estuaries and large rivers along the Pacific coast, including the Fraser, Columbia, San Joaquin, and Sacramento rivers. The longest of these, the Columbia River, drains about 260,000 km2. Since the turn of the previous century, many dams have been built throughout the Columbia River system, creating a series of isolated reservoirs. The largest remaining population of white sturgeon inhabits the lower Columbia River below Bonneville Dam. In general, the Columbia River supports larger populations of white sturgeon than the middle Snake River does. In the middle Snake River, only two river segments, those below Hells Canyon and Bliss dams, support sizable populations and show signs of recent reproduction (Cochnauer et al. 1985).The remaining segments of the middle Snake River support small populations and little or no detectable reproduction.

Idaho Power Company (IPC) is using population viability analysis (PVA) to assess the viability of white sturgeon populations and anticipate issues that may be raised when hydroelectric projects are relicensed on the middle Snake River. PVA uses models and data to compare the chances that a population will persist for some arbitrarily chosen time under alternative management practices (Boyce 1992). In our case, PVA is also part of the public process for dam relicensing, which involves the White Sturgeon Technical Advisory Committee (WSTAC), a group formed to provide technical guidance for sturgeon research activities undertaken by IPC during its relicensing efforts and develop mitigation actions to be proposed by IPC. Generally, after the WSTAC has been presented with PVA model results at committee meetings, the committee decides on new simulations to run, the results of which will be presented at future meetings. The PVA model was first used to rank how much various factors influenced simulated recruitment in each river segment. The results of these experiments are presented here and will also appear in Jager et al. (2001). More recently, the WSTAC has requested and been presented the results of simulation experiments to evaluate several options for restoring connectivity among river segments with and without additional mitigation measures. Although this PVA model has had drawbacks (e.g., model results are complicated and difficult to assimilate during a meeting, and the model’s development has had to occur simultaneously with the WSTAC process), its use has helped the committee to focus on the most important factors within each river reach and anticipate how consequences of actions in one reach may extend beyond that segment’s boundaries.

The overall goal of our population viability analysis is to evaluate various risks to the long-term persistence of white sturgeon populations in the middle Snake River. We typically predict the distribution of final population sizes and the likelihood of persistence, defined here as the proportion of replicate simulated populations that do not reach extinction (at least one individual of each sex alive) by the end of 200 years (y). The model is stochastic (i.e., one simulated replicate population may persist while another replicate population with the same parameter values becomes extinct) because of year-to-year variation in projected hydrologic conditions and individual variation in demographic events (birth, death, and migration).

We followed Beissinger’s (1995) guidelines for PVA development, where possible. First, we examined potential routes to species recovery and compared PVA projections for different

Page 2 Snake River White Sturgeon Conservation Plan Idaho Power Company scenarios rather than presenting absolute predictions. Second, we simulated demographic and genetic endpoints separately. Third, we presented sensitivities of model parameters. However, we did not follow two of Beissinger’s suggestions. First, because long-term data did not exist for these populations, we could not use such data to support the usual demographic analysis. However, we used an individual-based approach that often permitted us to substitute known attributes measured at the individual level. Second, though Beissinger recommends simulating over a short time horizon, we simulated over a relatively long time horizon (200 y) because white sturgeon have a long generation time.

The simulations described in this report evaluated multiple factors that may threaten the persistence of white sturgeon populations in the Snake River system. These results are intended to help the WSTAC team focus on the most effective recovery options.

2. STUDY AREA

The upstream boundary of our study area is Shoshone Falls, and the downstream boundary is Lower Granite Dam (Figure 1). The nine river segments are 1) below Hells Canyon Dam, 2) Oxbow Dam to Hells Canyon Dam, 3) Brownlee Dam to Oxbow Dam, 4) Swan Falls Dam to Brownlee Dam, 5) C.J. Strike Dam to Swan Falls Dam, 6) Bliss Dam to C.J. Strike Dam, 7) Lower Salmon Falls Dam to Bliss Dam, 8) Upper Salmon Falls Dam to Lower Salmon Falls Dam, and 9) Shoshone Falls to Upper Salmon Falls Dam.

We developed data to support our PVA model for the nine river segments of the middle Snake River. Each segment was characterized by its physical dimensions (average river width, segment length, and free-flowing length), downstream project characteristics (trash-rack spacing, percentage of flow entrained, and risk of turbine strike for sturgeon of different lengths), historical daily average flow and temperature records, and white sturgeon habitat suitability for different flows and life stages.

The PVA model is a metapopulation model that connects populations in adjacent river segments. This approach is more realistic than treating segments as separate, isolated populations where downstream (or upstream) passage is possible, and it allowed us to consider the potential costs and benefits of restoring connectivity among river segments.

3. METHODS

This part of the report has two sections: one describing the PVA model and its development and the other explaining model testing and application. 3.1. PVA Model Description

3.1.1. Model Scales: Spatial, Temporal, and Degree of Aggregation

Our PVA model represents serially linked reservoirs and free-flowing river segments that contain populations of white sturgeon connected by downstream migration. The PVA model uses an annual time step. We summarize important within-year influences as effects on demographic

Page 3 Idaho Power Company Snake River White Sturgeon Conservation Plan parameters and provide event-based representation of key environmental influences within a year (Figure 2). For example, we simulate recruitment by using parameter values estimated from a separate incubation submodel that uses a daily time step during spring, when spawning and incubation take place (see section 3.1.5.).

Our model simulates individuals to adequately represent variation among individuals and gain flexibility in representing risks and linkages with the river environment in a mechanistic fashion. Individual differences are particularly important for white sturgeon because of the high variability among individuals in reproductive tactics (age at first maturity and time intervals between spawning). An individual-based approach also simplifies the representation of some risks such as genetic risks associated with small, isolated subpopulations and the effects of management practices on individual attributes.

3.1.2. Linking Extinction Risk to River Hydrology

Because river flow has important effects on resident fish populations, representing the linkage between annual hydrologic conditions and population demographic parameters should be an important focus of riverine PVAs. Our PVA asked how long the population is likely to persist if historical hydrologic patterns continue. We characterized typical sequences of hydrologic years by dividing the historical record of annual river flow into dry, normal, and wet years. We classified inflows to Brownlee Reservoir between 1912 and 1995 as normal if flows were between the 80% exceedence level (163 thousand cubic feet per second [kcfs]) and the 20% exceedence level (273 kcfs). Wet and dry years fall on either end of this range. We simulated future environmental conditions in the middle Snake River by simulating stochastic sequences of hydrologic year types according to a Markov model (Table 1). The probabilities were estimated from the historical record described above. Beissinger (1995) describes this approach as an “Environmental states PVA.” We linked demographic parameter values to the different hydrologic year types as summarized in Table 2.

For white sturgeon, we explicitly represented three mechanistic sources of mortality that depend on temperature and river flow. First, the survival of eggs and larvae through spring depends on water temperatures remaining below critical levels until larvae develop into young-of-year fish. We estimated survival to age-1 in wet, normal, and dry years based on a relationship between survival and temperature for daily temperature series typical of each hydrologic year class during incubation. Second, survival to age-1 is known to be greater in years with higher spring flows. Therefore, we estimated first-year survival as a function of average spring flow. Third, survival of all ages through summer conditions in the reservoir environment depends on maintaining sublethal temperature and adequate dissolved oxygen.

3.1.3. Model Initialization

In the PVA simulations, we initialized the model by specifying the density of individuals per kilometer. Population estimates for one or two points in time are available for most river segments (Lepla and Chandler 1995a,b). In some segments, the numbers of sturgeon captured were too low to provide reliable population estimates. Long-term records of population size are not available in the Snake River.

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3.1.3.1. Age Distribution

The model generates a historical “founder” population with ages drawn from an exponential distribution with the mean age (A0) as its parameter. This distribution is consistent with a fixed mortality rate and can be fit to reported historical age structures for older age classes, while earlier age classes that are typically underrepresented by field samples are imputed.

3.1.3.2. Genotypes

At the start of the simulation, we assigned genotypes to founders. Each genotype has 10 neutral loci with 8 alleles that we assume are initially present in the population with frequency 0.125. We specified a fixed number (32) of possible alleles at each locus. The genotype of each individual in the initial population was drawn at random based on these initial allele frequencies for each locus because we assumed that loci are independent.

3.1.4. Reproduction

The PVA model evaluates reproduction annually for each subpopulation. We simulated reproduction in three phases (Figure 3b): we formed mating aggregations, determined the number of eggs produced by each female, and tracked genetic inheritance by offspring.

3.1.4.1. Mating Aggregations

White sturgeon form mating aggregations in spring when water temperatures rise above 13 °C and river flow is sufficiently turbulent. An ideal habitat for spawning is believed to consist of high water velocity and turbulent flow with nearby pools for staging and resting (Lepla and Chandler 1995b). Anders and Beckman (1995) found a correlation between discharge and the within-year timing of spawning in the lower Columbia River.

We begin simulating the white sturgeon life cycle by identifying the eligible pool of spawners in a given year. Whether a particular individual belongs to this eligible pool depends on its having reached maturity, its last spawning date, and its assigned rematuration interval. The onset of reproductive maturity is quite variable among individuals and differs between sexes. This variability is especially high in the Fraser River, where Semakula and Larkin (1968) found first- spawning females ranging in age from 11 to 34 y (11 to 20 y for males). The PVA model assigns initial ages at maturity from a normal distribution based on parameters estimated from Snake River adults (Table 3). The number of years between successive spawnings is also variable. Gonadal cycles are annual in males and biennial in females (Doroshov et al. 1997a). In the hatchery environment, female rematuration begins in the fall after spawning and is completed in the spring 18 to 20 months later. In the river environment, both sexes may wait up to 11 y between spawning (Semakula and Larkin 1968, Cochnauer 1983).

It is possible that delayed maturation and a long resting period between successive reproduction events is a response to density-dependent limitations in the river environment. We hypothesized that the number of years between spawning events increases when the density of adults is high enough to deplete food resources. Because sturgeon do not show territorial social behavior and are often seen foraging with others, we expected that density-dependent effects are egalitarian,

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applying equally to all individuals. This sort of density dependence can exert a strong negative feedback on population growth.

In years when the density of adults in a river segment exceeds the optimal density OptFshDen, we adjusted each adult’s spawning interval, I, by delay standard deviations for every percentage over the optimal density:

I, density≤ OptFshDen   I ' =  −density OptFshDen  (1) I+× SI_, SD delay  density > OptFshDen   OptFshDen 

We calculated density as the number of white sturgeon longer than 170 cm divided by the selected metric for habitat capacity (total river length, free-flowing river length, or weighted usable length for adults). This mechanism can delay first maturation as well as subsequent reproduction.

The second step in the model was to form spawning aggregations from the pool of eligible spawners. When Paragamian et al. (1996) studied the spawning movements of white sturgeon in the Kootenai River, Idaho, they tracked the same spawners moving from one site to the next in various configurations during the same season. Because their observations do not support the hypothesis that multiple spawning aggregations are reproductively isolated from one another, the PVA model assumes that reproduction is panmictic within river sections.

3.1.4.2. Fecundity

The fecundity of white sturgeon in the Snake River showed a linear increase with female size (Cochnauer 1983). Although the fecundity of very old females has been observed to decline or reach an upper limit with age in sturgeon (Doroshov et al. 1997b), such a decline was not evident in Snake River data for white sturgeon.

The model currently estimates fecundity of each female in two steps. First, a von Bertallanfy relationship with parameter values for the Bliss reach of the Snake River (Lepla and Chandler 1995a) estimates total length in cm from age in years:

Female total length = L∞ ()1− exp( Kvb ( Age + T 0 ) (2)

Next, we predict fecundity from fork length (DeVore et al. 1995). Fecundity and other parameters used in our simulations are defined in Table 3.

Number of eggs= feca {} Female fork length fecb (3)

3.1.4.3. Simulated Inheritance

After simulating egg production by females in the spawning aggregation, we simulated the inheritance of alleles by offspring. We assumed that all males in the spawning aggregation are equally likely to fertilize a given egg. At each locus, we drew one allele from each parent at

Page 6 Snake River White Sturgeon Conservation Plan Idaho Power Company random. We assumed that the white sturgeon genome is functionally diploid—i.e., all but two alleles per locus have been silenced (Van Eenennaam 1997).

After offspring inherit alleles from each parent, mutation from the inherited allele to a different one of the 32 possible alleles occurs randomly and infrequently. Mutation rates for white sturgeon have been reported to be low (Birstein et al. 1997). We adopted mutation frequency µ = 10–5 per locus and generation. According to the stepwise mutation model (Kimura and Ohta 1978), alleles are ordered along one dimension and assigned an index. Each mutation results in a shift from the inherited allele to the allele pointed to by a 1-unit increase, or decrease, in the index.

3.1.5. Incubation Submodel

We developed a daily incubation submodel for the spawning and incubation period in spring and early summer to simulate the three mechanistic mortality factors that operate during this time. This incubation submodel estimates the effects of temperature, flow, and habitat during incubation for each type of hydrologic year and each segment of the Snake River. The results are then provided to the PVA model as input parameters (Figure 4).

The incubation submodel simulates a sample of 100 female spawners (or batches of eggs) with different spawning dates. Though these individuals are not simulated in the main PVA model, their simulation in the submodel characterizes the range of environmental conditions encountered by white sturgeon during the spawning period. We constructed an empirical distribution of spawning temperatures for spawning dates estimated for eggs collected in the Snake River (mean = 14 °C). For each female, a spawning temperature threshold is drawn from the empirical distribution to define the start of incubation for her eggs (Figure 4). The end of the incubation period is determined, for each batch of eggs, by simulating successive days and accumulating degree-days, as a function of average daily temperature, Tt, until a developmental threshold is reached (Equation 4). On average, white sturgeon eggs develop into free-feeding larvae after 1,536 degree-days (Wang et al. 1985).

0.071 T {}24.Degree days = e t ∑t (4)

The incubation submodel was provided with historical daily average flow and temperature records for each river segment for the period from 1990 through 2000. These eleven years were made up of four dry years, three normal years, and four wet years. In addition, we provided a lookup table relating weighted usable area (WUA) for spawning and flow for each river segment. The submodel uses flow and temperature records for each segment and year to calculate three quantities over the incubation period for a sample of 100 females: 1) temperature-related survival, 2) average flow, and 3) minimum spawning WUA. We summarized these three quantities by calculating averages for years of the same hydrologic type and averages for the 100 females sampled each year. We then provided these averages to the main PVA model as site-specific input parameters (Table 4).

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3.1.6. Population Genetics

Our white sturgeon PVA model can simulate population genetic endpoints as well as demographic endpoints. Because the model is individual-based, we are able to assign a hypothetical genome to initial individuals and simulate inheritance in future generations. The model tracks changes in gene frequencies. As our genetic response variables, we report two indices describing change in the genetic diversity of neutral markers within and among populations. One index that we report is average heterozygosity, a commonly measured index of genetic diversity within populations. An individual’s heterozygosity measures the fraction of gene loci that have two distinguishable alleles. For each population, H is heterozygosity averaged over the loci of all individuals. HI, the average H over populations, is the probability of heterozygosity of any one gene drawn from the metapopulation. Because our simulated populations mate randomly, HI is approximately equal to HS, or the probability of heterozygosity of a gene drawn from an equivalent random-mating population.

Our second index, GST, quantifies the effects of population subdivision on inbreeding and reflects genetic differentiation among populations (Nei 1973). GST is an extension of the hierarchical F-statistics to the case of multiple alleles:

H − H = TS GST , (5) HT

where HT is the probability of heterozygosity of a gene drawn from an equivalent random-mating total population. Because mating is random in these simulations, population subdivision is the only factor contributing to inbreeding. In our simulations, both genetic drift (chance loss of alleles) and mutation (chance gain of alleles) can increase diversity among populations.

Although genetic endpoints were not reported for the simulations described in this chapter, the PVA model can be, and has been, used to predict the genetic consequences of river fragmentation (see Jager et al. 2001) or the genetic effects of alternative management scenarios, such as stocking or translocation.

3.1.7. Mortality

3.1.7.1. Baseline Mortality

Baseline mortality sets an upper bound on survival, Sy, of age-0 sturgeon (Table 3). First-year baseline mortality includes nonviable or unfertilized eggs (50% in a hatchery setting [Doroshov 1985]; 74% in the Kootenai River [Paragamian et al. 1996]), predation, and all other risks not explicitly included elsewhere in the model. Mortality during the first year can be as high as 99% (White Sturgeon Planning Committee 1992). The high fecundity of this species suggests that even higher levels of early mortality are typical (Winemiller and Rose 1992).

Natural survival rates of juvenile and adult white sturgeon are thought to be high because fast early growth makes them relatively invulnerable to predators (other than humans). Disease and

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starvation are likely the dominant components of natural mortality. Our simulations exposed juvenile and adult sturgeon to a baseline survival of Sj and Sa, respectively (Table 3).

3.1.7.2. Temperature-Related Mortality

Water temperature conditions during incubation may influence year-class strength in white sturgeon. In sturgeon species, early stages of development are the most sensitive to extreme temperatures (Nikol'skaya and Sytina 1979). Lethal temperatures and contaminants were suspected causes of high egg mortality (45%) in The Dalles pool, in contrast with lower mortality (approximately 19%) in adjacent impoundments (Anders and Beckman 1995).

The incubation submodel (Figure 4) estimated temperature-related survival from incubation through development of larvae to the free-feeding stage for years between 1990 and 2000 in each segment of the Snake River. We calculated temperature-related survival through this life stage, S1, from daily survival as shown in Equation 6. For a given day, t, we calculated daily survival, S(Tt), as a function of the average daily temperature, Tt (Figure 5). We used temperature-related survival data (Wang et al. 1985) from laboratory experiments with California stocks, requiring us to assume that Snake River stocks have similar tolerances. We assumed that temperatures below 6 ºC and above 21.5 ºC are lethal and that temperatures between 6 ºC and 17.5 ºC do not cause any significant mortality.

For a particular year and simulated batch of eggs, estimated temperature-related survival, S1 is

tfeed

SST1 = ∏ ()t , (6) t =1

where tfeed is the number of days for the eggs spawned by a given female to develop to the free- feeding stage. The PVA model uses the average temperature-related survival through incubation for each river segment and hydrologic year type (parameter S1 in Table 4). We estimated parameter S1 by averaging survival estimates over the simulated egg batches and years with similar (dry, normal, or wet) hydrology.

3.1.7.3. Flow-Related Mortality

Sturgeon are believed to benefit from spawning in high-velocity, turbulent waters. Various explanations have been proposed. High river flows may be needed to remove fine sediments from spawning areas (Votinov and Kas'yanov 1978). Broadcasting eggs in fast, turbulent water may enhance egg viability by dispersing adhesive eggs and preventing clumping. The tendency for egg predators to use slower water suggests that spawning in fast, turbulent water reduces predation on eggs. Dispersal by flow may also distribute eggs and thereby reduce competition (McCabe and Tracy 1994).

We hypothesized that flow-related survival, S2, follows a truncated linear model, increasing with average flow during incubation, Q , until the average flow reaches a threshold, Q*, above which flow-related survival is assumed to be 1.0. Empirical relationships involving flow are difficult to generalize to other sites because flow is usually a surrogate for less-easily measured variables such as velocity or turbulence. We therefore defined Q* as a segment-specific reference value set

Page 9 Idaho Power Company Snake River White Sturgeon Conservation Plan to a proportion, Qfact (Table 3), of the flow exceeded on 20% of the days during the spring (April, May, and June), Q20%. The value of Q20% was calculated for each segment based on historical flow data (Table 4).

Between 1989 and 1999, Counihan et al. (in press) evaluated the relationship between annual year-class strength of age-0 and age-1 white sturgeon in Bonneville Reservoir, below Dulles Dam. After removing the effect of temperature, they found a positive partial correlation of 0.42 between recruitment and average flow. We fitted Equation 7 with βQ = –5.1 to Bonneville Reservoir data to describe the relationship between the fraction of the maximum catch per unit effort (CPUE) of age-0 white sturgeon (used as a surrogate for survival, S2) and average spring flow, Q , (Table 3).

()QQ* −  β Q = e,*Q* QQ≤ S2  (7)  1,otherwise .

3.1.7.4. Habitat-Related Mortality

Because sturgeon use a variety of large-river habitat types, as well as coastal estuaries and ocean habitat, a much broader definition of habitat should ideally be used for this group than is typically applied to fishes (Beamesderfer and Farr 1997). Unfortunately, because no such measure of habitat quality has been developed for sturgeon, we must use weighted useable area (WUA) for juvenile and adult life stages. Our approach quantified WUA in free-flowing habitat, but we also supplemented this estimated WUA with a simple estimate of suitable habitat contributed by each reservoir (ResWul in Table 3). For reservoir habitat, we applied the depth suitability criteria to bathymetric data at a fixed time to estimate suitability for juveniles and adults. For free-flowing river habitat, we used habitat suitability criteria involving both depth and velocity to obtain a relationship between WUA and flow. Developing a relationship between WUA and flow requires habitat suitability criteria and historical data relating changes in depth and velocity to changes in river flow. We used historical daily flow data to estimate the average WUA for each hydrologic year type and river segment. Finally, we summed the free-flowing and reservoir values.

Age-0 White Sturgeon

Lack of suitable habitat for the number of white sturgeon eggs spawned can lead to density- dependent early mortality. Khoroshko and Vlasenko (1970) reported poor survival of sturgeon eggs on artificial spawning grounds with egg densities in excess of 3,500 eggs m–2. In our model, density-dependent survival does not decrease from 1.0 until the fraction of eggs at egg density, D, exceeds an upper density threshold, OptEggDen. At such high densities, density-dependent survival (factor S3) equals the proportion of the eggs in excess of the threshold.

 1,D≤ OptEggDen  S3 = OptEggDen (8)  , D> OptEggDen  D

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This source of mortality was not imposed in these simulation experiments, but we describe it here for use when the data needed as input become available.

Egg density was calculated as the number of eggs divided by the length of habitat suitable for spawning and incubation, the length of suitable habitat changing with flow. Ideal spawning conditions for white sturgeon occur in free-flowing rivers during seasonal floods, which normally occur during high spring runoff (Parsley et al. 1993, Anders and Beckman 1995, Marcuson et al. 1995, Beamesderfer and Farr 1997). Although white sturgeon spawning behavior has not been formally studied, informal observations indicate that the behavior of white sturgeon is similar to that of other sturgeon species. These observations typically describe aggregation of adult spawners in deep pools that serve as staging areas for rolling and leaping displays. Spawning takes place in fast, turbulent waters located nearby (Parsley et al. 1993).

We estimated the availability of habitat suitable for the incubation period by WUA per km of river. Studies relating WUA to flow have not yet been completed in all nine segments in the middle Snake River. Values of WUA_0 are listed in Table 4. We used the relationship among WUA, the area of suitable habitat, and flow that was developed by Chandler and Lepla (1997) for free-flowing sections of the Snake River. These site-specific WUA–flow relationships relied on habitat suitability data for newly spawned eggs reported by Parsley and Beckman (1994) and a hydraulic characterization of the Snake River by Anglin et al. (1992).

For each batch of eggs, the incubation submodel computed a minimum WUA over the incubation period for free-flowing sections of river (Figure 4). An average minimum WUA, computed for each hydrologic year type, was then provided to the main PVA model. The minimum WUA was lower in dry years than in normal years and lower in normal than in wet years for all segments of the Snake River having free-flowing habitat.

The value of reservoir habitat for spawning and incubation is uncertain. Successful spawning takes place during wet years in tailraces of dams on the Columbia River, where dam spacing is close enough to eliminate free-flowing habitat (Parsley and Beckman 1994). We assume that river segments with no free-flowing habitat contain a relatively short distance of suitable habitat in the tailrace, ResWul (Table 3), that is used only when no free-flowing habitat is available for spawning.

In river segments that also have free-flowing habitat, reservoir habitat may contribute or detract from WUA. By acting as a sink, reservoir habitat may detract from recruitment (Pulliam 1988), attracting spawners to areas that deteriorate in quality when changes in discharge or reservoir operations shift the locations of suitable habitat. Alternatively, reservoir habitat may be sufficiently riverine to contribute a small amount of habitat suitable for spawning and incubation. Our simulations assumed that reservoirs had no effect on WUA in segments with free-flowing habitat.

Juvenile and Adult White Sturgeon

Lepla and Chandler (1995a) quantified habitat suitability criteria for juvenile (≤ 120 cm) and adult (> 120 cm) white sturgeon for free-flowing habitat in the segment below Bliss Dam. They developed suitability criteria for each life stage by fitting a piecewise linear relationship between

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CPUE and depth and another between CPUE and velocity. Since the Bliss study, suitability criteria for use in the model have been updated with habitat-use data from other riverine sections of the middle Snake River. In general, juveniles and adults were more frequently found in deep habitat than in shallow habitat and in low-velocity habitat than in high-velocity habitat.

Hydraulic data were available for free-flowing sections of river below Lower Salmon Falls, Bliss, C.J. Strike, and Swan Falls dams. Field measurements of depth and velocity were taken at several flows at representative cross sections in a variety of free-flowing habitat types (e.g., pools, riffles, and runs). A hydraulic model was used to predict the depth and velocity distribution available in each segment at different flows. The suitability criteria were combined with these depth and velocity distributions to produce a relationship between WUA and flow.

In two river segments with free-flowing sections (below Shoshone Falls and below Hells Canyon Dam), hydraulic data have not yet been quantified. We inferred WUA below Shoshone Falls as follows: 1) we estimated the proportion of habitat in each habitat type (run, pool, riffle, and rapid) from aerial photographs; and 2) we then applied the estimates of WUA per unit length for low, median, and high flows for these four habitat types below Lower Salmon Falls Dam to the corresponding habitat types below Shoshone Falls. Hydraulic data are now being collected below Hells Canyon Dam. For the present, we assumed that the amount of suitable habitat below Hells Canyon Dam per unit of river length slightly exceeds that in the segment having the highest quantity because the Hells Canyon Dam segment is thought to have the best spawning habitat.

The influence of habitat quantity on survival of age-1 and older white sturgeon has not been quantified in the field. Therefore, we assumed that the effect of suitable habitat availability on survival follows a simple linear function of WUA for juveniles and adults, WUA_1. Two parameters of this relationship are the intercept, Shab_A and Shab_B (Table 3).

3.1.7.5. Larval Export

One theory to explain low recruitment in short reservoir segments of river is that early life stages are lost to downstream populations (Seyler 1997). Like many riverine fishes, the white sturgeon has an early life stage that is buoyant and disperses downstream. In reservoirs with high turnover rates, larvae may be unable to settle to the bottom before being swept downstream to the next river segment.

White sturgeon are particularly likely to move downstream during the first year of life. In the lower Columbia River, larvae were found downstream of sites where eggs had previously been observed (Parsley et al. 1993). Brannon et al. (1985) observed that larvae entered the water column immediately after egg-hatch and remained there for 1 to 5 days. Afterwards, larvae sought cover during the vulnerable stage of yolk-absorption. Larvae exposed to higher velocities initiated hiding behavior earlier. Larvae came out of hiding again at the larval-fry transition, a time marked by the initiation of feeding (Brannon et al. 1985). At this point, white sturgeon fry rose up into the water column, possibly to disperse from areas with insufficient food. During this stage (Brannon et al. 1985), the proportion of individuals in the water column increased to around 50%. Young-of-year fish have also been observed moving downstream later in the year, possibly following a natural pattern of outmigration (Coon et al. 1977). Lepla and Chandler

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(1995b) estimated that 6% of hatchery fry released above Bliss Dam in 1991 moved downstream and survived entrainment at some time before summer sampling two years later.

The PVA model simulates only the first mechanism, larval migration of age-0 fish. The proportion of larvae that migrate is estimated by the product of the probability that a larva will reach the reservoir, P{reservoir}, and the probability that a larva that has reached the reservoir will be swept downstream, P{swept/reservoir}. We assumed that spawning adults prefer free- flowing areas when they are available. The simulated probability that a larva enters the reservoir decreases exponentially as the length of free-flowing river, Lff, increases. The probability of a larva’s being swept downstream once it is in the reservoir decreases as its retention time, Retain, increases and as the duration of the demersal stage, LarvDur, increases. The retention time of each reservoir differs for the three hydrologic year types (Table 4). We estimated the proportion of larvae moving downstream according to Equation 9. Survival of larval export, S4, is simply the fraction not swept downstream.

SP4 = 1− {swept|reservoir} P {reservoir} 0, LL≥  ff 0  ()LLff − 0 PLLL{reservoir} =  , 10≤≤ff (9)  ()LL10−  PLL, ≤  sweep ff 1 LarvDur  , LarvDur≤ Retain P{swept|reservoir} =  Retain  1, otherwise. 

If free-flowing habitat is present, we assumed that spawning occurs there. Without knowing hydraulic details of a river segment, we supposed that larvae are less likely to be swept into the downstream reservoir in segments with longer free-flowing stretches of river. If we assume spawning aggregations are equally likely to occur anywhere in the free-flowing stretch, the average upstream distance of spawning sites increases with the length of the free-flowing habitat. As the upstream distance increases, both the distance that must be traveled to reach the reservoir and the opportunities for settling out of the water column also increase. We defined two parameters, L0 and L1, the free-flowing river lengths associated with a minimum (= 0) and maximum (= Psweep) probability of reaching the reservoir, respectively (Table 3).

3.1.7.6. Water Quality Mortality

During summer months, a combination of high water temperatures and low levels of dissolved oxygen (DO) in reservoirs can be lethal to white sturgeon. In July 1990, 28 sturgeon were found dead in Brownlee Reservoir, presumably because of anoxic conditions (DO < 1 mg L–1). Episodes of anoxic conditions in these reservoirs typically coincide with high summer temperatures. Thus, high water temperatures limit access to shallower but better oxygenated habitat, and anoxic conditions limit access to deeper habitat. Coutant (1987) referred to this situation as a “DO-temperature squeeze.”

In the PVA model, we used temperature and DO data for the day with the worst water quality to estimate the probability of surviving each factor. These formulations are described in the two

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following paragraphs for a given location, i. Once the two survival factors were calculated, we adopted the parsimonious assumption that the two risks are independent and multiplied the two survival values to obtain a joint survival.

Temperature tolerances are better known for juvenile sturgeon than for adult sturgeon. Wehrly (1995) observed excessive mortality in juvenile lake sturgeon at 23 ºC and concluded that this temperature may be the upper tolerance limit for this species. We also observed that juvenile white sturgeon appeared stressed upon exposure to temperatures exceeding 23 ºC. In the PVA model, survival, as described by Equation 10, decreases when temperature is between a lower threshold, LT, and an upper threshold, UT:

 0, TUTi >  TLT−  i  SLTTUTTii=  , ≤≤ (10) UT− LT    1, TLT<  i

Low levels of DO can also contribute to white sturgeon mortality in reservoirs. Klyashtorin (1974) presented DO thresholds shared by four species of Russian sturgeon over a range of temperatures. We fitted linear relationships, Equation 11, between DO thresholds (mg L–1) and temperature (T in ºC) to Klyashtorin’s data. The upper threshold, UDO, is the concentration below which respiration is depressed, and the lower threshold, LDO, is the concentration below which sturgeon are killed during short-term laboratory experiments. As shown in Equation 12, we assume that survival increases from zero to one, as DO increases from LDO to UDO.

UDO= 2.557 + 0.071 T , stressful (11) LDO= 1.052 + 0.027 T , lethal

0, DOi < LDO  DO− LDO  i  SDOii=  , LDO≤≤ DO UDO (12) UDO− LDO   1, DO> UDO  i

Equations 10 through 12 apply to any single location, i. We estimated population-level exposure to poor water quality spatially over the reservoir by assuming that the proportion of the sturgeon population exposed to poor water quality depends on the amount of refuge and the average risk in non-refuge areas for the current hydrologic year type. We also assumed that individuals are distributed evenly throughout the river segment prior to the worst summer episode. Each individual’s annual chance of surviving this episode, shown in Equation 13, depends on the fraction of river length that is risk free, DOfree, and the average survival in the remainder of the river length, SWQ. For a representative year of each type—dry (1992), normal (1995), and wet (1997)—we estimated DOfree and SWQ for the summer date with the poorest water quality conditions.

The water quality model developed for reservoirs (CE-QUAL-W2) predicted the spatial distribution of water quality conditions for two reservoirs, Brownlee and C.J. Strike. The

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remaining reservoirs have uniform spatial patterns in water quality that could be deduced from sparse field measurements. For each reservoir, we summarized water quality by producing a matrix of all combinations of temperature and DO in intervals of 1 ºC and 1 mg L–1, respectively. For each cell i in this matrix, we determined the volume of water within 2 m of the reservoir bottom, Vi, falling within this cell’s range of water quality conditions (Figure 6A), and we calculated the probability of survival, Si (Figure 6B), for a white sturgeon exposed to those conditions.

Survival(0)1(1)==×+ S4 for age individuals[] DOfree[ − DOfree× SWQ ] (13)

Because we assume individuals are evenly distributed throughout the river segment, the proportion of river length that is risk free is also the proportion of individuals with zero risk (survival = 1). For the remaining individuals, the chance of surviving temperature and DO conditions in the reservoir during the episode is SWQ.

    ∑VSiiiDO S T    i − DOfree  V S =  ∑ i (14) WQ  i ,

The assumption that individuals are uniformly distributed probably overestimates mortality because sturgeon can avoid poor water quality to some extent. We therefore added a threshold risk-free proportion, R*, to account for the ability of individuals to avoid poor water quality (Table 4). This proportion is needed because mortality estimates can be sensitive to assumptions about movement. Such sensitivity was demonstrated in another modeling effort in which a spatially explicit movement model was developed to simulate the movement of individual white sturgeon in Brownlee Reservoir (Sullivan et al. in press). The movement model uses a daily time-step and includes an advective component that represents movement in response to spatial gradients in water quality and a diffusive component that represents random exploratory movement. Individuals that fail to escape risky habitat by moving are subject to location-specific survival (SWQ). A comparison of survival predicted with and without movement showed that simulating movement doubled the predicted survival of white sturgeon through summer (Sullivan et al. submitted).

3.1.7.7. Turbine Mortality

The risk of turbine mortality depended on the size of an individual fish, the hydrologic year type, and the turbine type. Turbine mortality acted on age-1 and older sturgeon that migrate downstream. We assumed that 2% of the population migrated downstream annually, based on two estimates in the Snake River by K. Lepla. In other words, migration is considered a voluntary behavior of juveniles and adults. To move from above to below a dam, a sturgeon must be either spilled over the dam or entrained through the turbines. If an individual is migrating, its risk of entrainment through the turbines is estimated by the ratio of the volume of flow entrained by turbines to the total volume of flow (Figure 7A, Entrain in Table 4). As a result, survival is

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enhanced during wet years when a higher proportion of flow is spilled rather than routed through turbines.

The size-dependence of turbine mortality is specific to the hydroelectric project. We calculated turbine mortality from project-specific parameters using formulas developed for the appropriate turbine style: one for Kaplan turbines (Von Raben 1957, cited in Cada 1990) and another for Francis turbines (Nece 1991). For both styles, the probability that an entrained sturgeon would be struck by a turbine increased linearly with sturgeon length (Figure 7B, Strike in Table 4). This model assumes that any blade strike is lethal.

3.1.7.8. Angling Mortality

After 1970, the Idaho fishery regulations permitted only catch-and-release fishing, except for Native American tribes (Cochnauer 1983, Cochnauer et al. 1985). Although this policy has led to partial recovery of the populations affected (Lukens 1983, Cochnauer et al. 1985), populations are still exposed to hooking mortality, poaching, and legal harvest by native tribes.

We represented the likelihood of catching a given sturgeon as a function of its size, the size- selectivity of gear, and the fishing effort expended. We simulated the annual risk of angling mortality for a particular individual as a chance of its being captured and killed. The probability of capture for a given river segment j, Pcap, is the product of two risk factors that each increase from 0 to 1, scaled by fishing effort, Ej (Table 4). Factor F1 depends on the density of the population in segment j, Dj, and risk factor F2 depends on the size of the individual fish, L.

PEFDFLcap = jj12()() (15)

Fishing pressure typically increases with fish population density. We defined a density factor that follows a Holling Type-3 functional response to population density, where the density at which the inflection point occurs is Dh and the limit on daily catch/person is limit.

2 limit Dj FD1()j = 22 (16) DDh + j

Larger individuals are more vulnerable to capture and harvesting. To reflect this reality, we adjusted harvest risk for individual size, L, which we calculated from age. Sturgeon that are smaller than LCmin are not vulnerable to capture (i.e., F2(L) = 0), and those larger than LCmax are completely vulnerable (i.e., F2(L) = 1.0).

LLC− min FL2()= (17) LCmax − LCmin

We assumed that the risk of harvest is zero for sturgeon smaller than a minimum legal length, LHmin, and for sturgeon larger than a maximum legal length, LHmax, as set by fishing regulations. To simulate hooking mortality of fish that are captured but then released, we specified (Table 3) the probability of release, Prel and the probability of surviving hooking, Shook. The overall probability of surviving harvest and hooking mortality, SH&H, for a fish of size L is the following:

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−(1PPPSLHLLH )+ , ≤≤  cap cap rel hook min max S =  (18) HH& (1− PPSotherwise )+ ,  cap cap hook 3.2. Model Testing and Application

3.2.1. Simulation Experiments

To estimate the importance of the mechanistic mortality factors, we used the PVA model to simulate the final number of age-1 recruits for each river segment. We simulated 100 replicates of the middle Snake River populations for 200 y. Parameter values were obtained by the calibration described in section 3.1. (Tables 3 and 4). Mortality factors that were not of specific interest, such as baseline mortality, were included but did not vary among treatments in the simulation experiment presented here. The main prediction from the model was the recruitment to age-1 in the last year of the simulation. We compared a baseline scenario that included all mechanistic mortality factors operating on model fish with scenarios in which we removed various factors, one at a time. The following seven factors were considered:

• temperature-related mortality during incubation

• flow-related mortality during incubation

• downstream export of larvae

• episodes of poor water quality in reservoirs during summer (all ages)

• habitat-related mortality of juveniles and adults

• turbine strike following entrainment

• angling mortality (harvesting or hooking)

Although these simulations were intended to identify limiting factors rather than to make predictions about persistence, the baseline results can be used to infer the PVA model’s prediction of persistence in each river segment over a 200-y period.

3.2.2. Model Calibration

We calibrated the model by comparing current population sizes with those predicted by the model after simulating a 200-y period. The model was initialized with densities of 25 sturgeon/km in each river segment. We assumed an initial age distribution of age-1 and older fish that would result in the current size distribution below Hells Canyon Reservoir: 73% less than 95 cm, 22% between 95 and 170.5 cm, and 5% greater than 170.5 cm. For each segment, we compared model-predicted population densities in the final year with current field estimates of population densities. The three baseline mortalities (Sy, Sj, and Sa in Table 3) were calibrated in an automated fashion. We then adjusted mortality-related model parameters within the range of reported values until the predicted population densities were similar to those from field

Page 17 Idaho Power Company Snake River White Sturgeon Conservation Plan estimates. We also used comparisons of age distributions and catch data to guide decisions about which parameters to change.

3.2.3. Sensitivity Analysis

We conducted a sensitivity analysis using the PRISM software developed at Oak Ridge National Laboratory (ORNL) (Gardner et al. 1981). We included input parameters that were segment specific (i.e., those in Table 4) and not segment specific (i.e., those in Table 3), particularly those parameters associated with modeling the effects of mechanistic factors. For the segment-specific variables, we defined new parameters that served as multipliers of the values in Table 4, so that only one value was needed for all segments. The PRISM program drew a Latin-hypercube sample of parameters of size 5,000 from a multivariate normal distribution, with a 10% coefficient of variation surrounding the nominal value and no correlations among parameters (Table 3).

We conducted Monte Carlo simulation of the 5,000 parameter sets to predict recruitment. In Table 5, we report the relative partial sum of squares between model-predicted recruitment for each river segment and each parameter. 4. Results

The following three sections (4.1., 4.2., and 4.3.) describe three types of results: model calibration, simulation experiments to evaluate limiting factors, and sensitivity analysis. 4.1. Model Calibration

The results of model calibration are shown in Figure 8. The inset figure shows the relationship between population size predicted from the model and from field estimates. For river segments with populations too small to estimate, we used the actual number of white sturgeon captured. 4.2. Simulation Experiments

We compared recruitment predicted by two simulations: one including all mortality factors and the other removing each of the mechanistic factors of interest (Figure 9). Removal of each factor usually led to either no significant change or an increase in recruitment compared with the simulations including all factors (Figure 9A). In some cases, decreases can result from stochastic variation among simulations or from density-dependent effects.

Between Shoshone Falls and Upper Salmon Falls Dam1, habitat-related mortality acting on age-1 and older fish was the factor that, when removed, led to the greatest increase in simulated recruitment (Figure 9B). Although this segment is otherwise well suited for habitation by age-1 and older white sturgeon, much of the flow above Shoshone Falls is diverted for irrigation purposes.

1 A 2001 survey found a larger population than we used in our calibration. This population consists mainly of stocked white sturgeon.

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In the two short reservoirs below Upper Salmon Falls Dam and below Lower Salmon Falls Dam, eliminating larval export had the greatest potential to increase simulated recruitment (Figure 9B). The river segment between Bliss and C.J. Strike dams is relatively long and has one of the two largest populations in the middle Snake River. Our simulations suggested that small benefits resulted from removing each factor, but the greatest increase resulted from removing angling mortality (Figure 9B).

Between C.J. Strike and Swan Falls dams, angling mortality and larval export were the two factors that, when removed, resulted in the largest increases in recruitment. Turbine strike played a secondary role in limiting population. The segment below C.J. Strike Dam is known to be a popular site for catch-and-release angling of sturgeon.

In the three river segments between Swan Falls and Hells Canyon dams, the model predicted no recruitment after 200 y when all factors were present. Only by removing the factor of poor water quality did the model predict recruitment. In the river segment below Hells Canyon Dam, small increases in recruitment resulted from removing both angling and poor water quality. The effect of water quality occurs here because this factor must be mitigated upstream for those segments to provide a supply of downstream migrants below Hells Canyon Dam, where water quality is good.

The baseline simulations predicted that the three populations between Swan Falls and Hells Canyon dams would not be expected to persist for 200 y. It predicted that numbers in the three segments between Shoshone Falls and Lower Salmon Falls Dam would be very low. Three populations, two between Bliss and Swan Falls dams and the one below Hells Canyon Dam, were predicted to have more than 100 individuals. 4.3. Sensitivity Analysis

The most sensitive parameter was often found in the model for the dominant mechanistic factor in a segment (Table 5). Parameters Shab_A and WUA_1 were important in the segment between Shoshone Falls and Upper Salmon Falls Dam, where juvenile and adult habitat was predicted by the model to be the most limiting habitat. Parameter Psweep was important between Upper Salmon Falls and Bliss dams, where larval export was predicted to be the dominant factor. Parameter R*, which controls the ability of sturgeon to avoid poor water quality, was important between C.J. Strike and Oxbow dams. Poor water quality was identified by the model as a dominant factor in two of the three segments in this range (between Swan Falls and Oxbow dams). The segment between Oxbow and Hells Canyon dams was excluded because small variations in parameters did not alter recruitment predictions, which were always zero. Below Hells Canyon Dam, Shook, which is associated with angling mortality, was identified as important.

The sensitivity analysis identified demographic parameters for females, Agemat_avg and SI_avg, as important in river segments with relatively large simulated recruitment. The direction of effect of the parameter variations was as expected (i.e., increased age at maturity leads to decreased recruitment), which is encouraging.

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5. Discussion

The ranking of factors that were predicted by the model to influence recruitment differed among river segments, but the following hierarchical pattern emerged. First, we observed a clear distinction between river segments limited by episodic poor water quality and those with adequate water quality. Second, among river segments with better water quality, short river segments were regulated by different factors than longer segments were. These patterns are discussed below in three separate sections (5.1., 5.2., and 5.3.). 5.1. River Segments with Poor Water Quality

In segments with poor water quality in summer, this factor dominated all others. Poor summer water quality was important between Swan Falls and Hells Canyon dams. This factor even had indirect consequences downstream of Hells Canyon Dam because this reach receives fewer downstream migrants when water quality is poor upstream. The model predicted that removal of other factors would not be sufficient to reestablish recruitment in these populations unless water quality also improved.

Brownlee Reservoir experiences severe water quality degradation in dry and normal hydrologic years because of nutrient influxes from agricultural activity and municipal wastes from the surrounding watersheds. Only in wet years are summer flows high enough to prevent development of large populations of algae that produce anoxic conditions in the reservoir. 5.2. Short Reservoir Segments with Adequate Water Quality

Four short river segments (i.e., above Lower Salmon Falls, Bliss, Oxbow, and Hells Canyon dams; 11, 21, 19, and 42 km in length, respectively) consist primarily of impounded reservoir habitat. Field studies indicate that these reservoirs support very small white sturgeon populations (Figure 8) and produce no detectable numbers of young fish. Because of the close spacing of adjacent dams, these segments have little or no free-flowing habitat. The two segments between Upper Salmon Falls and Bliss dams do not have severe water quality problems. Larval export was predicted to be a limiting factor in these reservoirs. In short impounded segments of the Rio Grande and Pecos rivers of New Mexico (Plantania and Altenbach 1998), export losses have been implicated as a cause for the extirpations of broadcast-spawning cyprinids with semibuoyant eggs. In the case of white sturgeon, eggs are adhesive, and dispersal occurs later, during the larval and early juvenile life stages. Additional studies of the dispersal strategies and spatial ecology of this species are needed to evaluate minimum river length requirements.

We note that spawner limitation might also be an important cause of lost recruitment in short river segments. Because fewer adults are available to reproduce in these short segments, simulated opportunities for reproduction and recruitment are less frequent. As a result, small populations are typically more vulnerable to extinction than larger populations. Our simulation experiments were not designed to quantify spawner limitation in these reservoirs, but such effects of fragmentation are discussed more generally in Jager et al. (2001).

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5.3. Longer River Segments with Adequate Water Quality

Four longer river segments with adequate water quality are those below Shoshone Falls, Bliss, C.J. Strike, and Hells Canyon dams. We do not include the segment below Shoshone Falls in this discussion (see footnote on page 18). Identifying a single limiting factor was not as useful for these longer segments because recruitment showed a relatively weak response to several factors. Angling, larval export (or rather larval import from upstream), flow during incubation, turbine strike, and poor water quality had an impact in one or more of these longer river segments.

Two mortality factors that increase in proportion to population size tended to be important in the longer segments with larger populations, between Bliss and C.J. Strike dams and below Hells Canyon Dam. For example, angling reduced simulated recruitment between Bliss and Brownlee dams and below Hells Canyon Dam because angling pressure increased in these segments having higher sturgeon densities. Likewise, the importance of entrainment and turbine strike increases with the size of the upstream population. 5.4. Downstream Effects

In two instances, we observed a factor that was important to recruitment in a river segment, not because it was present within the segment but because of its influence on the upstream population. This circumstance explains the influence of poor water quality on the population below Hells Canyon Dam, which experiences good water quality but receives fewer immigrants from upstream populations when the effects of poor water quality upstream are simulated. A second example is the influence of larval export on the river segment between Bliss and C.J. Strike dams and the river segment between C.J. Strike and Swan Falls dams. These two longer segments experience lower immigration when populations in the two short segments upstream of Bliss dam dwindle in size. 5.5. Caveats and Future Directions

The relative importance of the seven factors for the nine river segments depends on assumptions and parameter values used by the PVA model. As new information becomes available (e.g., the new population estimates for the segment below Shoshone Falls), results will require revision.

Several factors that are often believed to negatively affect sturgeon recruitment were less important than expected in our model results. An example of these factors includes flow conditions during spawning and incubation. This decreased importance may indicate that the current model formulation will improve as we learn more about these processes. Data quantifying the amount of suitable habitat is not yet available for all river segments. Updating these values from our best estimates may change the results, and we plan to revise our estimates when these data become available.

Because relative ranking of the factors depends on parameter values that are, in some cases, best guesses, we will need to supplement this analysis with an uncertainty analysis. In contrast to sensitivity analysis, which identifies parameters with the greatest local influence, uncertainty analysis quantifies changes in model predictions (i.e., factor rankings) over a much broader range of possible parameter values (Drechsler 2000).

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Because mortality attributed to the mechanistic factors simulated here has not been quantified, field studies are needed to improve confidence in the choices of equations and parameter values. For example, our model predicted poor water quality and larval export as dominant factors limiting recruitment. Although the effect of low DO on early life stages has been studied in the lab (Klyashtorin 1974), the tolerances of juvenile and adult white sturgeon and the ability of all ages to avoid poor habitat are less well known and could benefit from further study. The interactions among factors, such as temperature and DO, are poorly understood and are not now represented in the model. Brief exposure to one factor may cause enough stress to increase the susceptibility to another factor, resulting in a greater cumulative impact. Larval export was also highlighted by our results as an important process that reduces recruitment in shorter river segments. Studies to quantify travel distances for larvae at different flows, as well as studies to quantify the effect of density on survival of early life stages, would provide valuable insights into this process. Clearly, there is no lack of opportunity for learning more about factors that influence white sturgeon recruitment in this highly modified large-river ecosystem. 6. Summary and Conclusions

The PVA process has been valuable in a number of ways. First, it provided us with a framework around which to organize existing information from the scientific literature and from researchers working in the Snake and Columbia rivers. Second, developing the PVA model to describe the relationships between river habitat and white sturgeon dynamics improved our intuition about these relationships. Third, we used the model to highlight key factors limiting white sturgeon recruitment in each river segment. Two important limiting factors identified by this analysis were poor water quality in Brownlee Reservoir and larval export from shorter river segments. Finally, the model predicted that persistence beyond the next 200 y is less likely in some river segments than in others under current operations. While the model can stimulate discussion and identify unanticipated relationships, other factors that are not included or are not sufficiently quantified to give precise quantitative predictions may be operating. Therefore, we recommend continued studies to quantify the parameters needed in PVA model relationships or directly test the importance of these factors affecting white sturgeon recruitment. 7. Acknowledgments

This research was sponsored by Idaho Power Company under U.S. Department of Energy (DOE) contract ERD-99-1813. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the DOE under contract DE-AC05-00OR22725. Phil Bates contributed his knowledge of white sturgeon biology during model development. Thanks are due to Jim Petersen and Mike Parsley (U.S. Geological Survey’s Cook Lab, Cook, WA) for reviews of a manuscript included in this report. 8. Literature Cited

Anders, P. J., and L. G. Beckman. 1995. White sturgeon spawning cues in an impounded reach of the Columbia River. In: R. C. Beamesderfer and A. A. Nigro, editors. Status and habitat requirements of the white sturgeon populations in the Columbia River downstream from McNary Dam. U.S. Department of Energy, Portland, OR.

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Anglin, D. R., T. R. Cummings, and A. E. Ecklund. 1992. Swan Falls instream flow study. U.S. Fish and Wildlife Service and Idaho Power Co. AFF1-FRO-92-14.

Beamesderfer, R. C. P., and R. A. Farr. 1997. Alternatives for the protection and restoration of sturgeons and their habitat. Environmental Biology of Fishes 48:407−417.

Beissinger, S. R. 1995. Modeling extinction in periodic environments: everglades water levels and snail kite population viability. Ecological Applications 5:618−631.

Birstein, V. J., R. Hanner, and R. DeSalle. 1997. Phylogeny of the Acipenseriformes: cytogenetic and molecular approaches. Environmental Biology of Fishes 48:127−155.

Boyce, M. S. 1992. Population viability analysis. Annual review of ecology and systematics 23:481−506.

Brannon, E., S. Brewer, A. Setter, M. Miller, F. Utter, and W. Hershberger. 1985. Columbia River white sturgeon (Acipenser transmontanus) early life history and genetics study. Bonneville Power Administration, Portland, OR. DOE/BP-18952-1.

Cada, G. F. 1990. A Review of Studies Relating to the Effects of Propeller-Type Turbine Passage on Fish Early Life Stages. North American Journal of Fisheries Management 10:418−426.

Chandler, J. A., and K. B. Lepla. 1997. Instream flow evaluations of the Snake River from C.J. Strike Dam to the confluence of the Boise River. In: Volume 1, Technical appendices for C.J. Strike Reservoir Hydroelectric Project. Idaho Power Co., Boise, ID. Technical Report E.3.1-C.

Cochnauer, T. G. 1983. Abundance, distribution, growth and management of white sturgeon (Acipenser transmontanus) in the middle Snake River, Idaho. Idaho Power Company, Boise, ID.

Cochnauer, T. G., J. R. Lukens, and F. E. Partridge, editors. 1985. Status of white sturgeon, Acipenser transmontanus, in Idaho. Dr. W. Junk, Dordrecht, The Netherlands.

Coon, J. C., R. R. Ringe, and T. C. Bjornn. 1977. Abundance, growth, distribution and movements of white sturgeon in the mid-Snake River. Research Technical Completion U.S. Department of the Interior, Washington, DC. Report Project B-026-IDA.

Counihan, T. D., J. D. DeVore, and M. J. Parsley. In press. The effect of river discharge and water temperature on the year-class strength of Columbia River white sturgeon. Transactions of the American Fisheries Society.

Coutant, C. C. 1987. Poor reproductive success of striped bass from a reservoir with reduced summer habitat. Transactions of the American Fisheries Society 116:154−160.

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DeVore, J. D., B. W. James, C. A. Tracy, and D. A. Hale. 1995. Dynamics and potential production of white sturgeon in the unimpounded lower Columbia River. Transactions of the American Fisheries Society 124:845−856.

Doroshov, S. I. 1985. Biology and culture of sturgeon acipenseriformes. Pages 251−274 in: J. F. Muir and R. J. Roberts, editors. Recent advances in aquaculture. Westview Press, Boulder, CO.

Doroshov, S. I., G. P. Moberg, and J. P. Van Eenennaam. 1997a. Observations on the reproductive cycle of cultured white sturgeon, Acipenser transmontanus. Environmental Biology of Fishes 48:265−278.

Doroshov, S. I., J. Van Eenennaam, and G. Moberg. 1997b. Reproductive conditions of the Atlantic sturgeon (Acipenser oxyrinchus) in the Hudson Estuary. Final report. Hudson River Foundation. Grant No. 007/91A.

Drechsler, M. 2000. A model-based decision aid for species protection under uncertainty. Biological Conservation 94:23−30.

Gardner, R. H., R. V. O'Neill, J. B. Mankin, and J. H. Carney. 1981. Comparison of sensitivity analysis and error analysis based on a stream ecosystem model. Ecological Modeling 12:173−190.

Jager, H. I., K. Lepla, J. Chandler, and W. VanWinkle. 2001. A theoretical study of river fragmentation by dams and its effects on white sturgeon populations. Environmental Biology of Fishes 60:347−361.

Khoroshko, P. N., and A. D. Vlasenko. 1970. Artificial spawning grounds of sturgeon. Journal of Ichthyology 10:286−292.

Kimura, M., and T. Ohta. 1978. Stepwise mutation model and distribution of allelic frequencies in a finite population. Proceedings of the National Academy of Sciences 75:2868−2872.

Klyashtorin, L. B. 1974. The sensitivity of young sturgeons to oxygen deficiency. Journal of Ichthyology 16:677−682.

Lepla, K. B., and J. A. Chandler. 1995a. A Survey of white sturgeon in the Bliss reach of the middle Snake River, Idaho. In: Volume 1, Technical appendices for new license application: Upper Salmon Falls, Lower Salmon Falls, and Bliss. Idaho Power Company, Boise, ID. Technical Report E.3.1-E.

Lepla, K. B., and J. A. Chandler. 1995b. A survey of white sturgeon in the Lower Salmon Falls reach of the middle Snake River, Idaho. In: Volume 1, Technical appendices for new license application: Upper Salmon Falls, Lower Salmon Falls, and Bliss. Idaho Power Company, Boise, ID. Technical Report E.3.1-B.

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Lukens, J. R. 1983. Hells Canyon Fishery Investigation (Little Goose Dam to Hells Canyon). Idaho Department of Fish and Game, Boise, ID. Job Performance Report Project F-73-R-5

Marcuson, P., V. Wakkinen, and G. Kruse-Malle. 1995. Kootenai River white sturgeon investigation. Annual Report 1994. Bonneville Power Administration, Portland, OR. DOE/BP-93497-6.

McCabe, G. T., Jr., and C. A. Tracy. 1994. Spawning and early life history of white sturgeon, Acipenser transmontanus, in the lower Columbia River. Fishery Bulletin 92:760−772.

Nece, R. E. 1991. Calculations for determining strike and pressure gradient. Pages 47-83 in: M. C. Bell, editor. Revised compendium on the success of passage of small fish through turbines. U.S. Army Corps of Engineers, Walla Walla, WA.

Nei, M. 1973. Analysis of gene diversity in subdivided populations. Proceedings of the National Academy of Science. 70(12): 3321−3323.

Nikol'skaya, N. G., and L. A. Sytina. 1979. A comparative analysis of the action of constant temperatures on the embryonic development of four species of sturgeons. Journal of Ichthyology 18:86−98.

Paragamian, V. L., G. Kruse, and V. Wakkinen. 1996. Kootenai River white Sturgeon spawning and recruitment evaluation. Chapter 1. Bonneville Power Administration, Portland, OR. DOE/BP-93497-11.

Parsley, M. J., and L. G. Beckman. 1994. White sturgeon spawning and rearing habitat in the lower Columbia River. North American Journal of Fisheries Management 14:812−827.

Parsley, M. J., L. G. Beckman, and G. T. McCabe, Jr. 1993. Spawning and rearing habitat use by white sturgeons in the Columbia River downstream from McNary Dam. Transactions of the American Fisheries Society 122:217−227.

Plantania, S. P., and C. S. Altenbach. 1998. Reproductive strategies and egg types of seven Rio Grande Basin cyprinids. Copeia 3:559−569.

Pulliam, H. R. 1988. Sources, sinks, and population regulation. American Naturalist 132:652−661.

Semakula, S. N., and P. A. Larkin. 1968. Age, growth, food, and yield of the white sturgeon (Acipenser transmontanus) of the Fraser River, British Columbia. Fisheries Research Board of Canada 25:2589−2602.

Seyler, J. 1997. Adult lake sturgeon (Acipenser fulvescens) habitat use, Groundhog River 1996. TR-035, OMNR, Northeast Science and Technology, Timmins, Ontario.

Sullivan, A. S., H. I. Jager, and R. Myers. In press. Modeling white sturgeon movement in a reservoir: the effect of water quality. Ecological Modelling.

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Van Eenennaam, A. L. 1997. Genetic analysis of the sex determination mechanism of white sturgeon (Acipenser transmontanus Richardson). Ph.D. dissertation. University of California, Davis, Davis, CA.

Von Raben, K. 1957. Zur frage der beschadigung von fischen durch turbinen. Die Wasserwirtschaft 4:97−100. English translation by: Fisheries Research Board of Canada Translation Series 448. Cited in Cada 1990.

Votinov, N. P., and V. P. Kas'yanov. 1978. The ecology and reproductive efficiency of the Siberian sturgeon, Acipenser baeri, in the Ob as affected by hydraulic engineering works. Journal of Ichthyology 18:20−29.

Wang, Y. L., F. P. Binkowski, and S. I. Doroshov. 1985. Effect of temperature on early development of white and lake sturgeon, Acipenser transmontanus and A. fulvescens. Environmental Biology of Fishes 14:43−50.

Wehrly, K. E. 1995. The effect of temperature on the growth of juvenile lake sturgeon, Acipenser fulvecens. State of Michigan Department of Natural Resources, Ann Arbor, MI. Fisheries Division Research Report 2004.

White Sturgeon Planning Committee. 1992. White sturgeon management framework plan. Pacific States Marine Fisheries Commission, Portland, OR.

Winemiller, K. O., and K. A. Rose. 1992. Patterns of life-history diversification in North American fishes: implications for population regulation. Canadian Journal of Fisheries and Aquatic Sciences 49:2196−2218.

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Table 1. Markov transition probabilities used to simulate future hydrology in the Snake River, Idaho.

To Hydrologic Year Type From type Dry Normal Wet Dry 0.31 0.56 0.13 Normal 0.18 0.64 0.18 Wet 0.11 0.50 0.39

Table 2. Links between annual hydrology and white sturgeon survival and reproduction simulated in the PVA model.

Life Stage and Process Link to Annual Hydrology Recruitment Wetter years provide better hydrologic conditions for survival of eggs and larvae. Survival of post-hatch Chances of settling to the bottom before washing downstream out of the larvae reach decrease as the retention time of a reservoir decreases. Retention times are shorter in wetter years. Survival of juvenile and Risk of mortality caused by episodes of summer anoxic conditions and adult sturgeon high temperatures depends on the perimeter volume-weighted risk of mortality in the reservoir (a function of hydrologic year type) and the amount of refuge (suitable free-flowing riverine habitat). Migration Chances of survival during migration depend on fish size and the risk of entrainment, a risk that increases in dry years when a higher proportion of flow is entrained.

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Table 3. Parameters of the white sturgeon PVA model and values used in this analysis.

Name Parameter Description Source and/or Equation Nominal Value –1 Sy Baseline first year survival rate (y ) Calibrated 0.00053 –1 Sj Survival rate of juveniles (y ) Calibrated 0.89 –1 Sa Survival rate of adults (y ) Calibrated; (Cochnauer 1983) 0.74 βQ Rate of decline in S2 vs. average flow Equation 7; (Counihan et al., in press) −5.1 Q* Relates threshold average flow for good Equation 7; Snake River data 0.60 recruitment to 20th percentile of spring flows OptEggDen Maximum egg density with no DD (# m–2) Equation 8; (Khoroshko and Vlasenko 1970) 3,500 ResWul Length of reservoir suitable for spawning (km) Fixed 1.0 LarvDur Duration of demersal larval stage (d) Equation 9; (Brannon et al. 1985) 1.0 LHmin, LHmax Lower, upper legal size limit (cm) Equation 18; Fixed 46.0, 300.0 LCmin, LCmax Non-catchable and fully catchable size (cm) Equation 15; (White Sturgeon Planning 43.0, 90.0 Committee 1992) L0, L1 Free-flowing distance with 0%, 100% chance of Equation 9; Calibrated 45.0, 12.0 reaching reservoir (km) Psweep Max. chance of being swept downstream Equation 9; Calibrated 0.7 Ssweep Survival of larvae swept downstream Calibrated 0.0001 LT, UT Lower, upper threshold temperature (ºC) Equation 10; (Wehrly 1995) 23.0, 28.0 Shook Survival of hooking Equation 18; Snake River estimate 0.96 limit Maximum per-capita harvest (# angler–1 d–1) Equation 16, Calibrated 3.0 Dh Density at inflection point of functional response in Equation 16, Calibrated 40.0 harvest (# km–1) Mig_down Annual downstream migration rate Snake River data 0.02 Mig_up Annual upstream migration rate Fixed 0.0 Agemat_avg Avg. age at first maturity for females, males (y) (Cochnauer 1983) 18.0, 14.0 Shab_A, Shab_B Intercept, slope of age-1+ survival vs. juvenile and Calibrated 0.71, 0.90 adult WUA (Table 4) Agemat_SD Std. dev. of age at maturity for females, males (y) (Cochnauer 1983) 1.5, 1.5 SI_avg Average spawning interval for females, males (y) Snake River data on proportion of adults 8, 2 spawning SI_SD Std. dev. of spawning interval for females, males Snake River data 0.8, 0.3 (y)

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Name Parameter Description Source and/or Equation Nominal Value feca, fecb Intercept, exponent of relationship between Equation 3; (DeVore et al. 1995) 0.072 fecundity (# of eggs) and fork length (cm) Kvb Change in fork length (cm) with age (y) Equation 2; (Lepla and Chandler 1995a) –0.045 T0 Initial age (y) –0.795 L∞ "Maximum" size of adults (cm) 275

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Table 4. Segment-specific parameters of the white sturgeon PVA model.

River segment above dam or landmark listed Hydro. Upper Lower Swan Brown- Hells Salmon Parameter description Name Year Salmon Salmon Bliss C.J. Strike Falls lee Oxbow Canyon River Dam location Dam_km All 989 933 922 902 795 737 459 439 398 Segment length (km) Seg_km All 56.51 10.62 20.44 106.7 58.41 277.93 19.31 40.88 95.91 Free-flowing (km) Lff All 46.02 0.17 11.58 60.83 38.62 185.68 0.00 0.00 95.91 Average width (km) Width All 0.14 0.21 0.13 0.22 0.28 0.30 0.22 0.25 0.12 Initial density (# km-1) N0 All 25 25 25 25 25 25 25 25 25 Initial % < 95 cm Plen[0] All 73 73 73 73 73 73 73 73 73 % 95 to 170.5 cm Plen[1] All 21.56 21.56 21.56 21.56 21.56 21.56 21.56 21.56 21.56 % > 170.5 cm Plen[2] All 5.44 5.44 5.44 5.44 5.44 5.44 5.44 5.44 5.44 -1 Harvest effort (d km ) Ej All 8 8 8 8 8 8 8 8 8 Prob. of release Prel All 1.0 1.0 1.0 1.0 0.99 1.0 1.0 1.0 0.98 Flow threshold (kcms) Q20% All 0.357 0.357 0.459 0.532 0.581 0.581 1.144 1.144 1.249 Slope of strike vs. size Strike All 0.011 0.005 0.010 0.011 0.005 0.011 0.012 0.011 0.006 Trash-rack spacing (cm) Trash All 23.0 23.0 23.0 22.2 13.3 15.2 12.7 14.0 0.0 Avoidance threshold R* All 0.78 0.78 0.78 0.78 0.67 0.78 0.78 0.78 0.78 Prob. entrainment Entrain Dry 0.96 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.0 Prob. entrainment Entrain Normal 0.78 0.99 0.97 0.98 0.99 1.00 0.96 0.97 0.0 Prob. entrainment Entrain Wet 0.52 0.95 0.86 0.87 0.94 1.00 0.76 0.79 0.0 Retention time (d) Retain Dry 0.07 1.04 0.57 18.78 0.52 62.5 2.91 8.21 0.0 Retention time (d) Retain Normal 0.05 0.76 0.47 15.57 0.41 44.95 1.95 5.16 0.0 Retention time (d) Retain Wet 0.05 0.41 0.28 10.46 0.23 24.71 1.46 3.03 0.0 Temp. survival S1 Dry 0.948 0.951 0.957 0.943 0.801 0.807 0.827 0.826 0.894 Temp. survival S1 Normal 0.834 0.929 0.890 0.871 0.787 0.782 0.872 0.873 0.879 Temp. survival S1 Wet 0.845 0.919 0.892 0.884 0.742 0.795 0.787 0.627 0.781 DO-T fraction risk-free DOfree Dry 1.000 1.000 1.000 0.516 0.000 0.041 0.060 0.045 1.000 DO-T fraction risk-free DOfree Normal 1.000 1.000 1.000 0.745 1.000 0.301 0.001 0.084 1.000 DO-T fraction risk-free DOfree Wet 1.000 1.000 1.000 1.000 1.000 0.067 0.709 0.752 1.000 DO-T avg. risk DOrisk Dry 0.000 0.000 0.000 0.950 0.300 0.878 0.883 0.764 0.000 DO-T avg. risk DOrisk Normal 0.000 0.000 0.000 0.941 0.000 0.799 0.711 0.611 0.000

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River segment above dam or landmark listed Hydro. Upper Lower Swan Brown- Hells Salmon Parameter description Name Year Salmon Salmon Bliss C.J. Strike Falls lee Oxbow Canyon River DO-T avg. risk DOrisk Wet 0.000 0.000 0.000 0.000 0.000 0.718 0.206 0.725 0.000 YOY WUA1 WUA 0 Dry 0.008 0.008 0.019 0.015 0.009 0.014 U2 U2 U2 YOY WUA1 WUA 0 Normal 0.008 0.008 0.019 0.016 0.032 0.023 U2 U2 U2 YOY WUA1 WUA 0 Wet 0.008 0.008 0.029 0.021 0.066 0.025 U2 U2 U2 Adult WUA1 WUA_1 Dry 0.005 0.057 0.026 0.120 0.006 0.179 0.163 0.172 0.2 Adult WUA1 WUA_1 Normal 0.005 0.057 0.026 0.120 0.006 0.179 0.163 0.172 0.2 Adult WUA1 WUA_1 Wet 0.005 0.057 0.026 0.120 0.006 0.179 0.163 0.172 0.2 Average flow (kcms) Qspawn Dry 0.019 0.154 0.155 0.208 0.194 0.199 0.358 0.327 0.312 Average flow (kcms) Qspawn Normal 0.151 0.187 0.186 0.241 0.344 0.344 0.998 1.000 1.011 Average flow (kcms) Qspawn Wet 0.237 0.385 0.372 0.426 0.494 0.459 0.916 1.013 1.011 1 Fraction of segment length 2 “U” indicates that the value is unknown and that we did not feel comfortable extrapolating from a similar segment.

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Table 5. Sensitivity of predicted final recruitment in the river segment above the dam (columns) to selected parameters (rows). The relative partial sum of squares is listed with a sign to indicate the direction of influence. Values range in magnitude from 0 to 1, where those smaller than 0.01 are shown as zeroes. We omitted the segment between Oxbow and Hells Canyon dams because variations in parameters did not lead to sufficient variation in recruitment (= 0).

Parameter Upper Lower Swan Salmon Name Salmon Salmon Bliss C.J. Strike Falls Brownlee Oxbow River Agemat_avg 0.0 0.0 0.0 0.0 0.0 0.0 0.0 –0.0337 Dh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 R*11 0.0 0.0 0.0 –0.1074 –0.0657–0.0903 0.0 0.0 DOfree1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 DOrisk1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Dtrash 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Effort1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Entrain1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 limit 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 L0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 L1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MaxFshDen 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Mig_down 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Psweep 0.0 –0.0146 –0.01680.0 0.0 0.0 0.0 0.0 QB 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Qfact 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Retain1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Shab_A 0.1015 0.0465 0.0 0.0 0.0410 0.0 0.0 0.0 Shab_B 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Shook 0.0333 0.0217 0.0 0.0501 0.0410 0.0 0.0 0.1422 SI_avg –0.0868 –0.0598 –0.0283 –0.1651 –0.1332 –0.0288 0.0 –0.3296 Ssweep 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Stempy1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Strike1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 WUA_11 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 R2 (%)2 0.2617 0.1668 0.0715 0.3603 0.3237 0.1367 0.0125 0.5242

1 Sensitivity to segment-specific parameters was determined by varying a multiplier around a value of 1. 2 Low R2 values suggest that random influences are important and call into question the sensitivity results for this response variable.

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Salmon River

Hells Canyon Dam Oxbow Dam Brownlee Dam Weiser River

Payette River Snake River

Boise River

Swan Falls Dam Lower & Upper Salmon C.J. Strike Dam Bliss Dam Falls dams

Shoshone Falls Figure 1. Nine river segments of the middle Snake River between Shoshone Falls and the confluence with the Salmon River.

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Figure 2. Overview of the PVA model. The incubation submodel calculates input parameters used by the PVA model to simulate three mechanistic influences on white sturgeon recruitment. Year-to-year variations in hydrologic year type are simulated as a first-order Markov process. Hydrologicyear type, in turn, influences white sturgeon survival.

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(A) Overview

Figure 3. Overview of simulated (A) overview and (B) reproduction.

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Select spawning temperature (T*) for this female.

Next spawner Next day

no no T > T* ?

stop

Multiply cumulative yes temperature survival, S1 , yes Last spawner ? by survival for this day.

Increment degree- days (DD)

Free-feeding? no yes DD > DD* ?

Figure 4. Flow chart of the incubation submodel depicting the estimation of temperature-related survival (S1) during incubation for one female’s eggs. The temperature threshold for spawning for a given female is T*, and the degree-day threshold for development into a free-feeding larva is DD*.

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1.0

0.8

0.6

0.4 Daily survival Daily

0.2

0.0 0 5 10 15 20 25 o River temperature ( C) Figure 5. The relationship between temperature-related survival and daily average river temperature simulated by our incubation submodel is based on laboratory studies by Wang et al. (1985).

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Temperature (oC) 5 10152025

7-8 0 0 0 20 ) (A) bottom volume 60 0 6-7 (1000-m 3) 40 0 0 5-6 0 20 20 40 40 0 4-5 8080 2020 60 60 3-4 0 16018020 120140 100 0 Dissolved oxygen (mg/l 2-3 20 0 0 0 0 40 204040 60 0 0 0 0 0 20 0-2 7-8 0.6 0.00.20.40.60.8 (B) survival (S i) 0.4 6-7 1.00.8 0.2

5-6 0.6 0.00.20.40.60.8 0.4 1.00.8 0.2 4-5 1.0

1.0 0.6 0.00.20.40.60.8 3-4 1.0 0.8 0.4 0.8 0.2 0.6

Dissolved oxygen (mg/l) oxygen Dissolved 0.8 2-3 0.6 0.4 0.6 0.4 0.2 0.4 0.2 0.2 0.00.20.40.60.8 0-2 5 10152025 o Temperature ( C) Figure 6. Simulated summer mortality caused by poor water quality in reservoirs based on total risk-free bottom volume and average mortality risk for the remaining bottom volume from distributions of (A) reservoir bottom volume (1000 m3) and (B) survival over the ranges of dissolved oxygen and temperature shown.

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(A) 1.0

0.8 Dry Normal 0.6 Wet

0.4

0.2 Proportion of flow entrained 0.0

n n s e ls e w n o o is ik l le o lm lm l tr Fa n b yo a a B S w x an S S J an ro O C r r C w B s pe e S ll p ow e U L Project H 1.0 (B)

0.8 Upper Salmon Lower Salmon Bliss 0.6 CJ Strike Swan Falls Brownlee 0.4 Oxbow Hells Canyon 0.2 Probability of blade strike

0.0 0 20406080100

Fish length (cm) Figure 7. Entrainment mortality of juvenile and adult white sturgeon that are migrating downstream results from two events: (A) entrainment of the fish through turbines (more likely in dry years), and (B) the turbine blade striking the fish (more likely for larger fish).

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70

60 Field Model 50 PVA model PVA 40

30 Field data

20 Population (#/km) density 10

0 s e s e r on on lis ik ll le ow on ve lm lm B tr Fa n xb ny Ri Sa Sa . S an row O Ca n er er .J w B ls o p w C S el alm Up Lo H S

Figure 8. Comparison of calibrated final population density simulated by the PVA model, including all mortality factors, with population density observed in the field.

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(A) 10

All factors Incub. temperature Incub. flow 1 Larval export Poor water quality Age 1+ habitat Recruitment (#/km) Turbine strike Angling

0.1

8 (B)

6

4

2

0 Change in recruitment after removing factor removing after in recruitment Change

n n m m ls m m n er o o a a al a a v lm lm D D F D D nyo i a a s e e a R S S s k an e w C n r li ri w nl bo s o e er B t S w x ll lm pp w . S o O e a U Lo J r H S C. B River segment above dam Figure 9. The effect of removing each mechanistic factor (Incub. = during incubation) on recruitment in each river segment is indicated by (A) the simulated final average recruitment and (B) the difference between simulated final average recruitment with all factors included and with one factor removed.

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Appendix 2. Conceptual Protection, Mitigation, and Enhancement Measures for Snake River white sturgeon.

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Appendix 2–1. Summary of conceptual protection mitigation and enhancement (PM&E) measures for Snake River white sturgeon. (Sources: White Sturgeon Technical Advisory Committee (WSTAC) meeting–November 29, 2000; Memorandum from Idaho Department of Fish and Game to Idaho Power Company, re: Conceptual PM&E measures for Snake River white sturgeon, January 19, 2001 [Appendix 2–2]; Electronic memorandum from Oregon Department of Fish and Wildlife to Idaho Power Company, re: Draft conceptual PM&Es for white sturgeon, May 4, 2001 [Appendix 2–3]; and Memorandum from U.S. Fish & Wildlife Service to Idaho Power Company, re: Draft conceptual PM&Es for white sturgeon, December 2000 [Appendix 2–4].

Reach Source Designation Conceptual Measures Idaho Department of All reaches of • The IDFG recommends a suitable, biologically based flow Fish and Game the Snake River regime for the Snake River from Shoshone Falls to Lower Granite Reservoir. The flow regime would protect and provide for the long-term health and persistence of white sturgeon, rainbow trout, bull trout, mountain whitefish, steelhead, salmon, lamprey, native nongame fishes, and instream, riparian and floodplain habitats, as well as invertebrate communities including listed molluscs. Some lower priority mitigation measures for IPC to consider might include funding for angler education and conducting surveys on angler effort directed at sturgeon. These could be useful for fishery management purposes. Shoshone Falls • The IDFG recommends the elimination of all daily load– to Bliss Dam following at Lower Salmon Falls Project during white sturgeon spawning and early life history period. The spawning and early life-history period is from March 1 through July 31. (Elimination of load-following during the spawning and early life history stages would also benefit rainbow trout, whitefish, federally listed molluscs, invertebrates, riparian and all aquatic species). • The IDFG recommends that daily load-following also be eliminated at Lower Salmon Falls Project during the remainder of the year. This measure is necessary in order to protect rearing sturgeon, rainbow trout, mountain whitefish, riparian habitat, and aquatic invertebrates including listed molluscs. • The IDFG recommends that IPC develop a Snake River White Sturgeon Conservation Plan (WSCP) that includes the following: 1) IPC shall develop the WSCP for FERC approval within one year of the issuance of new licenses for Bliss, Lower Salmon Falls, and Upper Salmon Falls projects or at the time new license applications for HCC are due, whichever occurs later, 2) The goal of the WSCP shall be to mitigate for project related impacts in order to provide for healthy populations of white sturgeon in each reach of the Snake River to Lower Granite Reservoir, except for the reaches between Hells Canyon and Oxbow dams and Upper Salmon Falls and Lower Salmon Falls dams, and 3) The WSCP shall have a basin wide focus and contain the following information: a) status of white sturgeon populations in the Snake River, b) reach-specific genetic profiles of

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Reach Source Designation Conceptual Measures Snake River whtie sturgeon populations, c) factors influencing population status, d) PME measures specific to each population of white sturgeon, e) an implementation schedule for PME measures, and f) a monitoring and evaluation plan to determine the status and trend of sturgeon populations and the effectiveness of PME measures. • IPC shall propose measures to restore connections between currently isolated white sturgeon populations. IPC shall address the need to provide gene flow among isolated sturgeon populations, restore white sturgeon migratory behavior, permit full utilization of available habitat, mitigate for entrainment losses, and replenish populations that are currently depressed. • IPC shall propose measures to mitigate for entrainment losses and turbine mortality. The following elements shall be included: 1) an analysis of the rates of entrainment which healthy white sturgeon populations would experience at the projects, 2) an analysis of effects of entrainment on recruitment and trend of these populations, 3) a determination whether estimated rates of entrainment would interfere with efforts to restore healthy sturgeon populations in each reach of the Snake River downstream to Lower Granite Reservoir, 4) necessary measures to minimize entrainment and turbine mortality of white sturgeon and other resident species, 5) protocols for trashrack and screen maintenance designed to minimize entrainment and injury of fish. • IPC should continue to be a key participant in state- sponsored efforts to improve water quality in the mid- Snake River

Bliss to • The IDFG recommends the elimination of all daily load- Swan Falls dams following at Bliss and C.J. Strike projects during the white sturgeon spawning and early life history period. The spawning and early life-history period is from March 1 through July 31. (Elimination of load-following during the spawning and early life history stages would also benefit rainbow trout, whitefish, federally listed mollusks, invertebrates, riparian and all aquatic species). • The IDFG recommends that daily load-following operations also be eliminated at the Bliss and C.J. Strike projects during the remainder of the year. This measure is necessary in order to protect rearing sturgeon, rainbow trout, mountain whitefish, riparian habitat, and aquatic invertebrates, including listed molluscs. •IPC shall propose measures to restore connections between isolated populations to restore gene flow, migratory behavior, permit full utilization of available habitat, mitigate for entrainment losses, and replenish populations that are currently depressed. • IPC shall propose measures to mitigate for entrainment losses and turbine mortality. The following elements shall be included: 1) an analysis of the rate of entrainment which healthy white sturgeon populations would experience at the projects, 2) an analysis of effects of entrainment on

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Reach Source Designation Conceptual Measures recruitment and trend of these populations, 3) a determination whether the estimated rates of entrainment would interfere with efforts to restore healthy sturgeon populations in each reach downstream to Lower Granite Reservoir, 4) necessary measures necessary to minimize entrainment and turbine mortality of white sturgeon and other resident species, (Note: At the C.J. Strike Project, the IDFG and IPC have documented dead sturgeon in the past two years resulting from turbine mortality. Apparently, sturgeon were able to swim into the downstream side of turbines during routine maintenance and were killed as the unit came on-line. Accordingly, IPC has installed a bubbler (compressed air blasts) that turns on as the gates begin to lift (Dale Allen, IDFG, personnal communication). This issue should be examined at all IPC hydropower facilities and remedied as nessary, and 5) protocols for trashrack and screen maintenance designed to minimize entrainment and injury of fish • IPC should continue to be a key participant in state- sponsored efforts to improve water quality in the mid- Snake River.

Swan Falls to • The IDFG recommends a biologically suitable flow regime Brownlee dams through the Swan Falls Project during the white sturgeon spawning and early life-history period. The spawning and early life-history period is from March 1 through July 31 (this scenario would also benefit rainbow trout, whitefish, federally listed mollusks, invertebrates, riparian and all aquatic species). • The IDFG recommends a suitable, biologically-based suitable flow regime through the Swan Falls Project for the remainder of the year. This measure is necessary to protect rearing sturgeon rainbow trout, mountain white fish, riparian habitat, and aquatic invertebrates, including listed mollusks. • IPC shall propose measures to restore connections between currently isolated white sturgeon populations. IPC shall address the need to provide gene flow among isolated sturgeon populations, restore migratory behavior, permit full utilization of available habitat, mitigate for entrainment losses, and replenish populations that are currently depressed. •IPC shall propose measures to mitigate for entrainment losses and turbine mortality. The following elements shall be included: 1) an analysis of the rate of entrainment which healthy white sturgeon populations would experience at the projects, 2) an analysis of effects of entrainment on recruitment and trend of these populations, 3) a determination whether the estimated rates of entrainment would interfere with efforts to restore healthy sturgeon populations in each reach downstream to Lower Granite Reservoir, 4) necessry measures to minimize entrainment and turbine mortality of white sturgeon and other resident species, and 5) protocols for trashrack and screen maintenance designed to minimize entrainment and injury of fish. • IPC should be a key participant in state-sponsored efforts to improve water quality in this reach of the Snake River. In

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Reach Source Designation Conceptual Measures recent history, mortalities of adult white sturgeon have occurred in upper Brownlee Reservoir due to low dissolved oxygen levels (<4 mg/l) caused by excessive nutrients, elevated water temperatures (>25 OC) and low river flows. Brownlee to • IPC shall coordinate with IDFG and Nez Perce Tribe (NPT) Oxbow dams to assess feasibility of limited hatchery production of white sturgeon for a targeted consumptive fishery for the NPT in Oxbow Reservoir. The IDFG would only consider this possibility if and when technology exists to produce infertile offspring from native stock to avoid potential introgression between hatchery progeny and wild Snake River sturgeon. Additionally, any released fish must be clearly marked as agreed upon for identification purposes. The IDFG does not endorse use of hatchery supplementation to rebuild populations of white sturgeon in the Snake River. The IDFG believes there are too many unknown factors including disease, gene swamping, competition etc. The IDFG will strongly oppose any effort to place hatchery fish in this reach if entrainment is possible into the wild and scenic corridor of the Snake River where there exists the healthiest white sturgeon population. • IDFG and NPT cooperate to evaluate methods and desirability of providing a limited harvest fishery on hatchery- origin sturgeon for NPT. Sturgeon populations may be supplemented only with native stocks. Again, this should not be construed that we endorse or support such a proposal. • If limited hatchery program for white sturgeon is deemed feasible for Oxbow Reservoir, IPC should explore potential for creating artificial habitat in order to increase survival and the carrying capacity. Hells Canyon • The IDFG recommends the elimination of all daily load- Dam to Lower following at the Hells Canyon Project during white sturgeon Granite spawning and early life history period. The spawning and Reservoir early life-history period is from March 1 through July 31. (Elimination of load-following during the spawning and early life history stages would also benefit rainbow trout, bull trout, Chinook salmon, steelhead, whitefish, federally listed mollusks, invertebrates, riparian and all aquatic species). • The IDFG recommends that daily load-following operations also be eliminated at the Hells Canyon Project during the remainder of the year. This measure is necessary in order to protect rearing sturgeon, rainbow trout, bull trout, chinook salmon, steelhead, pacific lamprey, mountain whitefish, riparian habitat, and aquatic invertebrates including the listed Bliss Rapids snail. Oregon Department Hells Canyon • Reconnect populations by removal of one, two, or all three of Fish and Wildlife Complex dams. (Brownlee, • Oxbow and Reconnect populations by providing upstream and Hells Canyon downstream passage within and through the Hells Canyon dams) Complex. • Increase minimum flows in the Oxbow bypass. • Minimize entrainment at Hells Canyon and Oxbow dams. • Improve water quality conditions in Brownlee Reservoir—

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Reach Source Designation Conceptual Measures i.e., aeration, operational changes. • Land acquisition and/or watershed riparian habitat improvement. • Flow management (increase minimum flows, ramping rates, eliminate load-following). • Increase and improve available spawning and rearing habitat. • Provide necessary flow and temperature regime to cue spawning. • Purchase water. • Replace lost marine derived nutrients. • Selective withdrawal from Brownlee Reservoir. • O & M funding • Transplant fish into Hells Canyon and Oxbow reservoirs. U.S. Fish and Lower Salmon • Monitoring between Lower Salmon–Bliss to determine Wildlife Service Falls to Bliss whether supplemental fish will remain, exported or entrained. dams • Evaluate whether this could be a terminal fishery area. • Fish ladders to lengthen reaches between Bliss and Upper Salmon Falls Bliss to C.J. • Develop index of successful reproduction Strike dams • Develop long-term monitoring program • No supplementation • Add in-river structure for additional spawning habitat C.J. Strike to •Supplementation to increase adult population Swan Falls •Habitat improvement to enhance spawning habitats (create spawning habitat) •Monitor/recapture program to evaluate growth, identify potential carrying capacity • Address poor water quality–offsite TMDL’s Swan Falls to •Contribute to TMDLs. Brownlee dams •No action until poor water quality is addressed. •Evaluate contaminant loading in white sturgeon. •Supplementation to improve adult population 10–20 yrs. Brownlee to • Supplementation for fishery only Oxbow dams • Research and monitoring to determine whether white sturgeon will rear and stay in reservoirs. Oxbow to • Supplementation for fishery only Hells Canyon • dams Research and monitoring to determine whether white sturgeon will rear and stay in reservoirs. Hells Canyon • Continued monitoring. Dam to Lower

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Reach Source Designation Conceptual Measures

Granite • Modeling to determine what factors are benefiting sturgeon Reservoir downstream. White Sturgeon Lower Salmon • Buy reserve water Technical Advisory Falls to Bliss • Improve habitat for spawning and incubation life stages Committee • Consider translocation/ fish ladders • Increase minimum flow • Cease/alter load-following • Improve communication with USBR • Artificial propagation Bliss to C.J. • Buy reserve water Strike • Improve habitat for spawning and incubation life stages • Change level of intake at C.J. Strike Dam • Continued involvement with TMDLs • Cease/alter load-following • Evaluate translocation/fish ladders • Improve communication with USBR

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Appendix 2–2. Idaho Department of Fish and Game conceptual protection, mitigation, and enhancement measures for Snake River white sturgeon.

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–2. (Cont.)

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Appendix 2–3. Oregon Department of Fish and Wildlife conceptual protection, mitigation, and enhancement measures for Snake River white sturgeon. (Source: electronic memorandum)

Oregon Department of Fish and Wildlife

Draft Conceptual PM&Es for White Sturgeon May 4, 2001

• Reconnect populations by removal of one, two, or all three dams.

• Reconnect populations by providing upstream and downstream passage within and through the Complex.

• Increase minimum flows in oxbow bypass.

• Minimize entrainment at HC and Oxbow dams.

• Improve water quality conditions in Brownlee Reservoir – e.g. aeration, operational changes.

• Land acquisition and/or watershed riparian habitat improvement.

• Flow management: Increase minimum flows. Ramping rates Eliminate load following • Increase and improve available spawning and rearing habitat.

• Provide necessary flow and temperature regime to cue spawning.

• Purchase water.

• Replace lost marine derived nutrients.

• Selective withdrawal from Brownlee Reservoir.

• O&M Funding.

• Transplant fish into HC and OX reservoirs.

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Appendix 2–4. United States Fish and Wildlife Service conceptual protection, mitigation, and enhancement measures for Snake River white sturgeon. United States Fish and Wildlife Service

Draft Conceptual PM&Es for White Sturgeon December, 2000

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Appendix 2–4. (Cont.)

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Appendix 2–4. (Cont.)

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Appendix 2–4. (Cont.)

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Appendix 3. White Sturgeon Technical Advisory Committee comments to the draft Snake River White Sturgeon Conservation Plan.

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Appendix 3–1. Idaho Department of Fish and Game comments to the draft Snake River White Sturgeon Conservation Plan.

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Appendix 3–1. (Cont.)

Idaho Department of Fish Game

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Idaho Department of Fish Game

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Idaho Department of Fish Game

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Idaho Department of Fish Game

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Idaho Department of Fish Game

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Appendix 3–1. (Cont.) Response to Comment WIFG2-1

The WSTAC recommended that population assessments in the Hells Canyon reach evaluate the sturgeon population between Hells Canyon and the Salmon River, which is commensurate with the long-term goal established by the WSTAC (stated in section 6.1. of the WSCP). A prior population assessment in this reach conducted by IPC shared data-collection responsibilities with the Nez Perce Tribe. In that assessment, the NPT was responsible for sampling the Snake River between the Salmon River confluence and Lower Granite Dam as well as the lower Salmon River. Nevertheless, as described in the WSCP, IPC intends and has proposed (see section 8.8.2.4.) to sample the entire reach between Hells Canyon and Lower Granite dams. Response to Comment WIFG2-2

IPC assumes that IDFG is referring to proposed measures rather than recommended measures. Three of these IPC-proposed measures are in fact feasibility studies, all of which occur in the C.J. Strike to Swan Falls reach. The first feasibility study focuses on the ability to construct suitable spawning and incubation habitat. The second feasibility study investigates entrainment, impingement, and trash bar spacing at the project. Nested within the entrainment study is the third feasibility study, designed to determine the amount of entrainment that is occurring at C.J. Strike Dam by the use of an acoustic camera. IPC believes that it is premature to begin identifying all possible alternatives without first completing and discussing results from the feasibility studies. Response to Comment WIFG2-3

IPC does not believe that the WSCP places too much initial emphasis on conservation aquaculture. It is included only as a potential option for future consideration, which the IDFG has stated may be an eventual and/or necessary measure under a long-term adaptive management plan. It is IPC’s understanding that the IDFG’s management plan for Snake River white sturgeon also includes the potential for aquaculture in the same reaches that were identified in the WSCP. IPC also understands that the decision of whether to pursue conservation aquaculture will be made by the IDFG. Response to Comment WIFG2-4

Although the specific objectives and details of this study have yet to be developed by IDFG, IPC does not anticipate that study results would be site specific but would rather focus on a sturgeon’s physiological response to catch-and-release angling. IPC anticipates that applying this individual physiological response to Snake River sturgeon populations would require quantifying reach specific angler effort, which falls beyond the scope of investigations proposed by IPC. IPC believes that quantifying angling pressure and its potential impacts to white sturgeon is the responsibility of state management agencies. Nevertheless, as stated in section 8.5.6.3, IPC is willing to provide study support by supplying radio telemetry receivers, aerial antennas, and

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Appendix 3–1. (Cont.) radio transmitters to complete the field portion of the study, as well as applying the study results to the white sturgeon PVA model where applicable.

Response to Comment WIFG2-5

IPC believes that the proposed measures would significantly restore and enhance habitat conditions for Snake River sturgeon. IDFG’s comment ignores the measures proposed by IPC, especially those that would improve water quality. Also, it is important to note that, while IDFG is not required to balance power and nonpower values, IPC and FERC are required to balance these values. Response to Comment WIFG2-6

Given that the Hells Canyon–Lower Granite sturgeon population shows good recruitment, it appears that load following in the upper reaches of the free-flowing section does not have a significant impact on natural production. Stock assessments conducted between 1972 and 2000 show juvenile fish less than 92 cm TL continue to dominate the population, and size groups greater than 92 cm TL have steadily grown since the 1970s. The percentage of middle-sized sturgeon (92−183 cm TL) has increased from 4%, as sampled from 1972 to 1975 (Coon et al. 1977), to 18%, as sampled from 1982 to 1984 (Lukens 1985), to 29%, as sampled from 1997 to 2000. Similarly, larger sturgeon (> 183 cm TL) have also increased from 2%, as sampled from 1982 to 1984, to 18%, as sampled from 1997 to 2000. This current stock structure closely resembles IDFG’s desired management goal of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL. IPC believes that the Hells Canyon–Lower Granite sturgeon population exhibits a healthy population structure based on the current stock structure, which is dominated by juveniles and the wide range of size classes and stages of maturity from immature juveniles to reproducing adults.

Figure 1 shows the timing of spawn intervals (10−18 °C) and spring runoff available to the Hells Canyon–Lower Granite sturgeon population. Based on temperature and flow data between 1990 and 2000, which includes drought to record high flows, peak spring flows and spawn intervals below the Salmon River confluence coincide each year. In the upper portion of the Hells Canyon–Lower Granite reach (Hells Canyon Dam to the Salmon River), peak spring flows (when available) coincide with spawn intervals. During low-flow years, peak spring flows are typically not available to the Snake River as a result of water management practices (refilling of storage reservoirs for agriculture) in the upper basin. However, even at low flows of 5,000 cfs in the upper section of the reach, suitable spawning conditions are still met. Spawning habitat is the most available habitat of any sturgeon life stage in this reach (Technical Report E.2.3-2 in the New License Application: Hells Canyon Hydroelectric Project). In any one of these years, suitable conditions for reproduction are available to the sturgeon population within the Hells Canyon–Lower Granite reach.

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Appendix 3–1. (Cont.)

Spawn period below Salmon River confluence Flow at Anatone Gauge (below Salmon River) Spawn period between Hells Canyon Dam and Salmon River Flow at Hells Canyon Dam

160 1991 1992 1993 1994 1995 140 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct

160 1996 1997 1998 1999 2000 140

Mean Daily FlowMean Daily (kcfs) 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Month Figure 1. Mean daily flow and spawn periods for white sturgeon in the Hells Canyon–Lower Granite reach of the Snake River.

Response to Comment WIFG2-7

While IDFG is not required to balance power and nonpower values, IPC and FERC are required to balance these values. In making its decision on what measures to propose, IPC considered many factors related to both power and nonpower values, including the long-term viability of white sturgeon, state management policy, customer rates, system reliability and stability, and environmental impacts that would result from constructing any new facilities. Response to Comment WIFG2-8

IDFG’s comment regarding the impacts of hydroelectric projects on Snake River white sturgeon ignores other factors that have and continue to negatively impact sturgeon which are largely beyond the control of IPC including, most notably, water quality impacts from other basin users and irrigation withdrawals from the upper Snake River basin.

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Appendix 3–1. (Cont.) Response to Comment WIFG2-9

Monitoring will be an integral part in evaluating long-term population trends as well as determining the effectiveness of various measures. Accordingly, a significant portion of funds has been allocated to such tasks. Because of the adaptive nature of the WSCP, actual costs that have been initially identified may change, depending on the effectiveness of proposed measures, results of feasibility analyses, or future information about sturgeon biology and management.

IPC believes that many “on the ground” improvements, such as improvements in water quality, in sturgeon habitat are being implemented and will significantly restore and enhance habitat conditions for Snake River white sturgeon. IDFG’s comment does not take into account these measures proposed by IPC for improvement of water quality. Although costs associated with water quality measures are not included in the cost estimates in the WSCP, IPC has committed funds and indicated its willingness to implement water quality measures throughout the Snake River. For instance, the following measures have been implemented by IPC as required by the water quality certification and consent order for the Shoshone Falls, Upper Salmon Falls, Lower Salmon Falls, and Bliss projects:

• Annually assist ($15,000 per year) in further development and implementation of the Idaho Department of Environmental Quality’s (IDEQ) middle Snake River watershed management plan/total maximum daily load (TMDL).

• Provide funding ($3,000,000 one time) for acquisition of spring resources on the middle Snake River to protect and enhance water quality and aquatic species habitats.

• Provide funding ($750,000 one time) for design, development, and construction of artificial wetlands, settling ponds, and other systems and facilities to prevent or reduce nutrients and sediments from entering the middle Snake River.

• Annually provide funding ($50,000 per year for ten years) to IDEQ for monitoring of long-term water quality conditions and changes.

Additionally, the following measures have not been implemented at this time but are proposed to be implemented after the FERC licenses are issued:

• Design, install, and operate equipment at the Upper Salmon Falls, Lower Salmon Falls, and Bliss projects to remove aquatic vegetation collected on trash racks.

• Maintain a minimum flow of 50 cfs in the North Channel at Upper Salmon Falls.

In addition, the IDEQ has issued a § 401 water quality certificate for the C.J. Strike Project, and as part of that certification, IPC is 1) providing $50,000 annually for TMDL development and, 2) after completion of the TMDL, will cooperate and implement measures to achieve IPC allocations.

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Appendix 3–1. (Cont.)

IPC has also proposed several water quality measures to improve water quality in reaches associated with the HCC. As part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971), IPC has proposed to implement its DO load allocation identified in the draft Snake River–Hells Canyon TMDL by using reservoir aeration techniques in Brownlee Reservoir. Additionally, IPC has proposed to install and operate turbine-venting, or an equivalent oxygen supplementation system, at Brownlee Dam as a means to improve DO levels in Oxbow and Hells Canyon reservoirs and the tailwaters of Hells Canyon Dam. IPC has also proposed installing flow deflectors at Hells Canyon Dam to reduce TDG levels during periods of spill. Also, it is important to note that, while IDFG is not required to balance power and nonpower values, IPC and FERC are required to balance these values. Response to Comment WIFG2-1

IDFG’s comment mischaracterizes IPC’s proposed operations. See IPC’s new license application for the C.J. Strike Project and responses to FERC’s additional information requests. Response to Comment WIFG2-11

IPC acknowledges that the movement behavior of white sturgeon following translocation to the Bliss–C.J. Strike reach is unknown. The potential for individuals to return downstream exists, given that downstream movement of white sturgeon at C.J. Strike Dam has been documented by the recovery of marked fish below that dam. In fact, it is important that downstream movement of fish from the Bliss–C.J. Strike reach continues in order to provide recruitment to the C.J. Strike–Swan Falls reach. The WSCP clearly states that translocation of sturgeon to the Bliss–C.J. Strike reach would be conducted on an experimental basis and employ radio telemetry to monitor movement behavior of translocated fish. For instance, such monitoring would identify whether sturgeon immediately attempt to return downstream to the C.J. Strike–Swan Falls reach. If such behavior occurs, translocation of reproductive adults would be discontinued until further evaluation.

IPC has proposed using acoustic cameras at C.J. Strike Dam to evaluate entrainment potential, including the number and size of sturgeon, seasonal occurrence, and use of spillway and/or turbine routes across varying hydrologic years. If study results indicate turbine entrainment of sturgeon, IPC has further proposed evaluating the feasibility of reducing trash bar spacing. IPC believes experimental translocation could be implemented concurrently with evaluations of entrainment potential without creating significant risk to either the Bliss–C.J. Strike or C.J. Strike–Swan Falls sturgeon populations. Response to Comment WIFG2-12

IDFG misinterprets and confuses IPC’s response. IPC made two points in its response. First, under Idaho law, IPC cannot obtain or acquire water for the purpose of improving water quality or for any other resource or aesthetic instream use. Second, the water resources of the upper Snake River basin are overappropriated and that fact, together with the U.S. Bureau of Reclamation’s efforts to acquire and/or lease Idaho storage water for downstream augmentation

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Appendix 3–1. (Cont.) purposes, results in little, if any, storage water being available for other purposes, such as hydropower. IDFG responds that IPC can obtain water for hydropower use and argues that water from upper Snake River reservoirs remains available, either through storage space acquisition or rental, for such purposes. IPC agrees that Idaho law allows IPC to acquire water, through purchase or rental, for hydropower purposes. But that is neither responsive to IDFG’s initial comment nor does it change the shortage of water in the upper Snake River basin. IPC stands by its response: IPC cannot obtain water for the purpose of increasing flows in the middle Snake River. Response to Comment WIFG2-13

IPC believes that the WSCP is evidence of IPC’s willingness to work with state and federal resource agencies and tribes. Also, it is important to note that, while IDFG is not required to balance power and nonpower values, IPC and FERC are required to balance these values. Response to Comment WIFG2-14

Comment noted.

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Appendix 3–2. United States Fish and Wildlife Service comments to the draft Snake River White Sturgeon Conservation Plan.

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Appendix 3–2. (Cont.)

U.S. Fish and Wildlife Service

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Appendix 3–2. (Cont.)

U.S. Fish and Wildlife Service

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Appendix 3–2. (Cont.) Response to Comment WFWS2-1

Comment noted. Response to Comment WFWS2-2

The Service states that, if the draft WSCP had been included in the DLA, it would have provided more comments. However, at the last WSTAC meeting on August 8, 2002, which the Service attended, IPC indicated that the draft WSCP would be available to the WSTAC for review and comment in March 2003, prior to IPC’s finalizing and filing the WSCP with the FERC in July 2003. The Service made no indication to IPC or the WSTAC that this schedule was unacceptable. Response to Comment WFWS2-3

IPC believes that the WSCP is evidence of IPC’s willingness to cooperate with state and federal resources agencies and tribes. Also, it is important to note that, while the Service is not required to balance power and nonpower values, IPC and FERC are required to balance these values. Response to Comment WFWS2-4

The Service has misinterpreted the information presented in paragraph 3 of page 24. Based on movements of telemetered spawners, collection of eggs and larvae, and instream flow assessments, suitable spawning conditions are provided in the canyon corridors below Bliss, Swan Falls, and Hells Canyon dams. This availability of suitable spawning conditions is likely why spawning sturgeon did not travel far or to dam tailraces in these particular reaches. This behavior contrasts with that of spawners below C.J. Strike and Oxbow dams that were documented to travel to the dam tailraces. As indicated in the WSCP, these reaches provide limited spawning habitat conditions and lack canyon corridors that provide suitable conditions (staging pools in proximity to turbulent runs and rapids) used by sturgeon below the Bliss, Swan Falls and Hells Canyon projects. In the case of the C.J. Strike–Swan Falls reach, spawners were located in the tailrace of the C.J. Strike Dam; however, IPC did not state that this activity constituted spawning suitability for this particular reach. In fact, IPC stated that spawning conditions are generally not available to sturgeon below C.J. Strike Dam (regardless of flow or project operations). Therefore, IPC has proposed translocation of reproductive-sized sturgeon to the Bliss–C.J. Strike reach where spawning conditions are available. As the Service is aware, the effects of projects operations on sturgeon habitats (summarized in the WSCP) have been evaluated at Lower Salmon Falls (Brink 2000), Bliss (Brink and Chandler 2000), Swan Falls (Chandler and Lepla 1997), Oxbow (Myers and Chandler 2001), and Hells Canyon dams (Chandler et al. 2002).

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Appendix 3–2. (Cont.) Response to Comment WFWS2-5

The percentages of spawning females estimated from IPC’s stock assessments below Bliss (13%) and Hells Canyon dams (11%) were higher than that observed for the C.J. Strike sturgeon population (4%). The Service states that one possible explanation for the low percentage of spawning females below C.J. Strike Dam is that project operations having a negative effect on vitellogenesis and that the WSCP should consider this rationale since no text was presented to explain the low number of spawning females. However, the Service also indicated that they did not review the WSCP in its entirety. A possible explanation, rationale, and proposed measure were presented in section 8.5.6.

Typically, only 10% of the sturgeon population is reproductive in any given year. Given that Bliss and Hells Canyon project operations can vary river flow, yet reproductive potential remains at levels expected in a typical sturgeon population, IPC believes that a possible explanation for the low percentage of female sturgeon spawners downstream of C.J. Strike Dam may be related to the intensive angling pressure that occurs in the C.J. Strike tailrace. Angler catch records below C.J. Strike Dam have indicated that this tailrace area is the section of the Snake River that is most intensively fished for sturgeon in Idaho. Several studies of different species of fish have shown that exhaustive exercise, including that caused by angling, results in a variety of severe physiological disturbances, including altered reproductive performance and delayed mortality (citation within the WSCP). In section 8.5.6., IPC has proposed to provide study support for evaluating the impacts of catch-and-release angling on white sturgeon below C.J. Strike Dam, in cooperation with the IDFG. Response to Comment WFWS2-6

The measures proposed by IPC in relicensing its projects, including the WSCP, would significantly restore and enhance habitat conditions for Snake River white sturgeon. The Service’s reference to “maintaining status quo” fails to take into account these measures. The Service’s comment also ignores water quality, irrigation withdrawals, sport fishing, and other factors over which IPC has no control that have negatively impacted and continue to impact Snake River white sturgeon. In addition, it needs to be noted that, while the Service is not required to balance power and nonpower values, IPC and FERC are required to balance these values. Response to Comment WFWS2-7

The measures proposed by IPC constitute the “action” part of the WSCP.

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Appendix 3–3. Oregon Department of Fish and Wildlife comments to the draft Snake River White Sturgeon Conservation Plan.

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.)

Oregon Department of Fish and Wildlife

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Appendix 3–3. (Cont.) Response to Comment ODFW4-1

ODFW's comment stating that IPC hydroelectric projects are the primary reason for the current poor condition of several Snake River white sturgeon populations ignores other factors that have and continue to negatively impact sturgeon which are largely beyond the control of IPC including, most notably, water quality impacts from other basin users and irrigation withdrawals from the upper Snake River basin.

Response to Comment ODFW4-2

Reservoir construction and development in the Snake River basin in general (not just IPC mainstem dams) has altered many of the natural features of the river.

Response to Comment ODFW4-3

ODFW's concern that the Hells Canyon - Lower Granite sturgeon population remains at only half (17 fish/km) of the management goal (32 fish/km) ignores the positive changes that have occurred in the Hells Canyon - Lower Granite sturgeon population and perhaps more importantly, that the applicability of the management goal across all Snake River reaches is unknown. The overall status of the Hells Canyon - Lower Granite sturgeon population should not be based solely on the target density of 32 fish/km. A significant change in the population's stock structure has occurred over the past 30 years. Since the initiation of more restrictive fishing regulations in 1972, the abundance of sturgeon greater than 92 cm TL has steadily grown and the percentage of sturgeon 92 to 183 cm TL, the legal harvestable size prior to 1972, has increased from 4% in 1972-1975 (Coon et al. 1977) to 18% in 1982-1984 (Lukens 1985) to 29% in 1997- 2000 (Lepla et al. 2001). Sturgeon greater than 183 cm TL have also increased in abundance from 2% in 1982-1984 to 18% in 1997-2000. It may take another 25 years for the larger length group (>183 cm TL) in the Hells Canyon reach to approach full recruitment (Cochnauer 2002). As this larger size class becomes more abundant with reproductive adults, there is the potential for further increases in population productivity to occur in the future. Although the population may still be recovering from the effects of historical harvest, the current stock structure is dominated by juveniles which indicates strong recruitment to the population and resembles the desired management target of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL.

As stated in the WSCP, applying a target density of 32 fish/km for all Snake River reaches should be used as an interim standard until future evaluations determine whether a single reach wide target is appropriate or reach specific density targets are needed. The target goal of 32 fish /km was determined from a model simulation of the Bliss - C.J. Strike population (T. Cochnauer, IDFG, personal communication to WSTAC May 8, 2001). The target density currently assumes that stream and reservoir habitats (based on maximum channel depth) in other reaches can

17 Snake River White Sturgeon Conservation Plan Idaho Power Company support similar densities of sturgeon observed in the Bliss-C.J. Strike reach. The applicability of this index to other Snake River reaches in not known. As future population monitoring is conducted, target densities for specific reaches may need to be refined, pending data about growth rates and condition factor and results of additional modeling of reach properties that influence the success of white sturgeon populations.

Response to Comment ODFW4-4

TDG levels above the state standards occur relatively infrequently and do not occur most years as indicated by ODFW’s comment.

Response to Comment ODFW4-5

ODFW’s comment fails to recognize that the magnitude and seasonal shift in water temperature is also related to inflow water temperature into Brownlee Reservoir and not solely attributed to project operations.

Response to Comment ODFW4-6

Comment noted.

Response to Comment ODFW4-7

The onset of white sturgeon spawning, incubation and larval development begins approximately 4 to 5 days later when comparing available temperature regimes from 1955-1958 (pre-Hells Canyon Complex) and 1990-2000 (post Hells Canyon Complex) (Figure 1). Most notable is the substantial increase in duration of suitable water temperatures (about 16 to 20 days) for each of the life stage intervals when comparing pre- and post-HCC temperature regimes. These data suggest the current temperature regime below Hells Canyon Dam has benefited white sturgeon by increasing the number of days with suitable water temperature for successful early life stage development.

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Appendix 3–3. (Cont.)

Spawn Pre-HCC Post-HCC dateCol 5 vs vs HCD hcd kcfskcfs b Incubation Pre-HCC Post-HCC

Larvae Pre-HCC (yolk-sac) Post-HCC Pre-HCC Larvae (exogenous) Post-HCC Pre-HCC Age-0 Post-HCC

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

Figure 1. Comparison of life stage intervals for Snake River white sturgeon based on temperatures regimes from 1955-1958 (pre Hells Canyon Complex) and 1990-2000 (post Hells Canyon Complex). The occurrence of various life stage intervals was calculated based on the initiation of spawning using median Julian dates associated with lower (10 °C) and upper (18 °C) water temperature limits suitable for spawning and subsequent embryonic development by Wang et al. (1985). Below, Figure 2 shows the timing of spawn intervals (10-18 OC) and spring run-off available to the Hells Canyon - Lower Granite sturgeon population. Based on temperature and flow data between 1990-2000 (which includes drought to record high flows), peak-spring flows and spawn intervals below the Salmon River confluence coincide each year. In the upper portion of the Hells Canyon - Lower Granite reach (Hells Canyon Dam to the Salmon River), peak spring flows (when available) also coincide with spawn intervals. During low flow years, peak spring flows are typically not available to the Snake River as a result of water management practices (refilling of storage reservoirs for agriculture) in the upper basin. However, even at low flows of 5,000 cfs in the upper section of the reach, suitable spawning conditions are still met. Spawning habitat is the most available habitat of any sturgeon life stage in this reach (Technical Report E.2.3-2). In any one of these years, suitable conditions for reproduction are available to the sturgeon population within the Hells Canyon - Lower Granite reach.

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Appendix 3–3. (Cont.)

Spawn period below Salmon River confluence Flow at Anatone Gauge (below Salmon River) Spawn period between Hells Canyon Dam and Salmon River Flow at Hells Canyon Dam

160 1991 1992 1993 1994 1995 140 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct

160 1996 1997 1998 1999 2000 140

Mean Daily FlowMean Daily (kcfs) 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Month Figure 2. Mean daily flow and spawn periods for white sturgeon in the Hells Canyon - Lower Granite reach of the Snake River.

Furthermore, there is no indication that recruitment has been negatively affected by temperature regimes below Hells Canyon Complex. Stock assessments conducted between 1972 and 2000 have juvenile fish less than 92 cm TL continuing to dominate the population and size groups greater than 92 cm TL have steadily grown since the 1970s. The percentage of middle-sized sturgeon (92-183 cm TL) has increased from 4%, as sampled from 1972 to 1975 (Coon et al. 1977), to 18%, as sampled from 1982 to 1984 (Lukens 1985), to 29%, as sampled from 1997 to 2000. Similarly, larger sturgeon (> 183 cm TL) has also increased from 2%, as sampled from 1982 to 1984, to 18%, as sampled from 1997 to 2000. This current stock structure resembles the desired management goal of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL. IPC believes the Hells Canyon - Lower Granite sturgeon population exhibits a healthy population structure based on the current stock structure, which is dominated by juveniles and the wide range of size classes and stages of maturity from immature juveniles to reproducing adults.

20 Snake River White Sturgeon Conservation Plan Idaho Power Company

Appendix 3–3. (Cont.) Response to Comment ODFW4-8

The extent of temperature-related mortality in Snake River sturgeon populations is unknown. White sturgeon are considered a cool/coldwater species, a classification that suggests they are better suited to water temperatures below 25 °C. In culture facilities, water temperatures from 18 to 22 °C are considered to be optimal for sturgeon growth; California sturgeon farms often use this temperature range for production (S. Doroshov, UC Davis, pers. comm. electronic mail). Water temperatures in several reaches of the Snake River routinely peak near 24 to 25 °C during the summer and might increase the risk of mortality; however, IPC has not observed nor is aware of any sturgeon mortalities directly related to elevated water temperatures in the Snake River. IPC telemetry studies have tracked several Snake River sturgeon throughout summer maximums approaching 24 to 27 °C and found no mortality among these individuals. Although the specific upper lethal threshold temperature for white sturgeon is unknown, it likely occurs somewhere between 28 and 30 °C. IPC posed this hypothesis to S. Doroshov (UC Davis, pers. comm. electronic mail) who believed that this assumption was accurate.

Response to Comment ODFW4-9

IPC has proposed measures to improve water quality in the Hells Canyon Complex. IPC has indicated its willingness to work with IDEQ and ODEQ to develop measures that address IPC's assigned load allocations for improving water quality in the HCC.

Response to Comment ODFW4-10

IPC is also uncertain as to the effects of elevated TDG levels to white sturgeon. Based on capture and radio-tagging information, there is nothing to suggest a large-scale change in distribution, although there may be localized changes in distribution. IPC does know that at least older life stages of white sturgeon prefer depths that would reduce or remove any effect of elevated TDG. However, early life stage affects are uncertain, especially the larval drift phase. The depth distribution of larval drift remains unknown. Below Hells Canyon Dam, white sturgeon show strong evidence of successful reproduction in all years, and the biological validity and applicability of the management goal (as discussed above) remains uncertain. Further, effects from TDG would not be an annual event, and efforts are taken to abate spill whenever possible. Certainly the proposed flow deflectors for Hells Canyon Dam will also reduce the frequency of elevated TDG events. Assessment of the Brownlee and Oxbow effects are much more problematic because of the very low numbers of sturgeon. IPC believes that the short isolated reaches and subsequent loss of larval and older age classes of sturgeon are primary limiting factors for these two reaches. However, IPC will continue to take operational measures to minimize elevated TDG below Brownlee and Oxbow dams.

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Appendix 3–3. (Cont.) Response to Comment ODFW4-11

IPC has proposed measures to improve water quality in the Hells Canyon Complex that include project effects on TDG. IPC has indicated willingness to work with IDEQ and ODEQ to develop measures that address IPC's assigned load allocations for improving water quality in the HCC.

Response to Comment ODFW4-12

Reference to Idaho and Oregon's water quality standards have been added in Section 7- Recommended Measures by WSTAC.

Response to Comment ODFW4-13

ODFW has stated that IPC must identify all impacts to Snake River white sturgeon populations. PVA model simulations have identified factors limiting to Snake River sturgeon of which larval export was one factor affecting recruitment in short reaches. However, ODFW then says the lack of specific field observations on larval export brings into question the validity of this factor. Jager et al. (2001) clearly stated the model assumptions and that results are predictions on simulated recruitment. IPC is aware of the lack of field specific information on larval export and also the difficulty in sampling this particular life stage. However, IPC does not believe this provides a basis for ignoring the model's prediction of export as a potential limiting factor and the several lines of evidence suggesting sturgeon export as a plausible factor occurring within short reaches of the Snake River.

A common observation in reaches associated with both the mid-Snake three-dam complex and the Hells Canyon three-dam complex was little or no detectable presence of sturgeon. Of these reaches where sturgeon were sampled, the majority of fish were typically adults suggesting no recent recruitment. While some of these reaches may not furnish all the necessary habitats for early life stage development, the Lower Salmon Falls - Bliss reach offers a good example where early life stage habitats are available and reach length appears primarily responsible for the lack of recruitment. Hydrologic and water quality regimes in the Lower Salmon Falls - Bliss reach are similar to those observed below Bliss Dam (where a stronghold population exists), yet few wild sturgeon remain within the 13 mile reach between Lower Salmon Falls and Bliss dams. The short reach length appears conducive to high downstream losses (particularly early life stages) versus longer Snake River reaches. During the larval dispersal phase, white sturgeon larvae are planktonic and capable of drifting long distances by using the river currents. McCabe and Tracy (1993) and Kohlhorst (1976) reported sturgeon larvae about 115-121 miles downstream from known egg incubation and probable spawning sites. These distances far exceed the reach lengths for the mid-Snake and Hells Canyon three-dam complexes. The dispersal phase may last up to six days (Brannon et al. 1986). The retention time of Oxbow and Hells Canyon reservoirs can range from 1.5 to 3 days at flows between 20 kcfs and 28 kcfs.

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Appendix 3–3. (Cont.)

The low number of hatchery sturgeon sampled in the Lower Salmon Falls - Bliss reach further suggests that short river segments are conducive to downstream export. A total of 2,560 hatchery fish were stocked below Lower Salmon Falls Dam from 1989 to 1994, although few hatchery sturgeon were recaptured during the 1992-1993 population assessment. Several hatchery sturgeon from the Lower Salmon Falls - Bliss reach have been collected downstream of the Bliss Dam. Juvenile and adult sturgeon have also been recaptured below C.J. Strike (n = 6) and Swan Falls dams (n = 1) that originally were tagged in the adjacent upstream reaches. Downstream movement of sturgeon among Columbia River reaches has also been documented. There is no reason to assume that Oxbow and Hells Canyon reservoirs are unique to the extent that sturgeon export would not occur from these pools.

Response to Comment ODFW4-14

The Population Viability Analysis indicated water quality, low spawner abundance and sturgeon export were limiting factors in Oxbow and Hells Canyon reservoirs. The Brownlee-Oxbow and Oxbow-Hells Canyon reaches are two relatively short river segments in the Snake River. A common observation in short reaches of both the Mid-Snake and Hells Canyon complexes has been little or no detectable presence of sturgeon. Not only does the relatively close spacing of adjacent dams limit the amount of available habitat, but the short distance between dams probably contributes more to downstream losses of sturgeon than do longer reaches, particularly for sturgeon in early life stages. White sturgeon larvae are planktonic and can drift long distances in river currents. In addition, the reservoirs may also be affecting recruitment success of sturgeon by increasing egg and larval predation by species associated with reservoir environments. IPC does not believe changes in project operations below Oxbow or Brownlee dams for spawning will improve recruitment of sturgeon to these reaches for reasons discussed above and in Section 9.7 of the WSCP. In addition, Technical report E.2.3-1 within the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971) determined suitable habitat conditions below Oxbow Dam exist for white sturgeon spawning across a wide range of flows. Water temperature regimes suitable for spawning also exist.

ODFW recommended in the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971) that IPC conduct a study to test whether sturgeon are reproducing in these reservoirs and that larval export is limiting. Yet, ODFW has repeatedly stated their opposition to using sturgeon from the Hells Canyon - Lower Granite reach as a potential donor population for translocation and finding other suitable donor population is unlikely. Given the low numbers of sturgeon in the pools, testing this hypothesis would first require transplanting sufficient numbers of reproductive adults to increase spawner abundance in order to begin evaluations of spawning/recruitment success. IPC does not believe such a test is warranted. However, if such a test were undertaken, IPC questions where the reproductive adults would come from in order to begin such evaluations?

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Appendix 3–3. (Cont.) Response to Comment ODFW4-15

IPC has clearly indicated that the WSCP is not a management plan, nor is it intended to replace existing management plans for Snake River white sturgeon. IPC also acknowledged in the WSCP that the jurisdiction, management, and protection responsibilities are rightfully those of relevant state and federal fish and wildlife agencies and Native American tribes. IPC also recognizes the water quality authority of ODEQ and has clearly indicated its willingness to work with IDEQ and ODEQ. Regarding water quality measures for the HCC, IPC stated that the specific details regarding design and operation of such measures be developed through consultation with ODEQ and IDEQ within the context of the § 401 water quality certification process.

Response to Comment ODFW4-16

The WSTAC recommended that population assessments in the Hells Canyon reach evaluate the sturgeon population between Hells Canyon and the Salmon River, which is commensurate with the long-term goal established by the WSTAC (stated in Section 6.1. of the WSCP). A prior population assessment in this reach conducted by IPC shared data-collection responsibilities with the Nez Perce Tribe. In that assessment, the NPT was responsible for sampling the Snake River between the Salmon River confluence and Lower Granite Dam as well as the lower Salmon River. Nevertheless, as described in the WSCP, IPC intends and has proposed (see Section 8.8.2.4.) to sample the entire reach between Hells Canyon and Lower Granite dams.

Response to Comment ODFW4-17

The WSCP is intended to serve as a master plan for guiding the implementation of feasible protection, mitigation, and enhancement measures for Snake River white sturgeon populations impacted by IPC's hydroelectric projects. These measures are designed to help ensure the species' long-term persistence and restore opportunities for beneficial use. This plan outlines proposed measures and strategies for Snake River white sturgeon that IPC would implement once the WSCP were accepted and new project licenses issued by FERC.

The short-term objectives of the WSCP are to maintain and/or enhance population viability and persistence of white sturgeon below Bliss and Hells Canyon dams and, where feasible, begin to reestablish recruitment to populations where natural recruitment is severely limited. It is important to note that IPC is not required to speculate about what were pre-project conditions. It is also important to note that, while ODFW is not required to balance power and nonpower values, IPC and FERC are required to balance these values.

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Appendix 3–3. (Cont.) Response to Comment ODFW4-18

Because of the adaptive nature of the WSCP, actual costs that have been initially identified may change, depending on the effectiveness of proposed measures, results of feasibility analyses, or future information about sturgeon biology and management.

IPC believes considerable emphasis has been placed on habitat improvements. ODFW's comment does not take into account measures proposed by IPC for improvement of water quality. Although costs associated with water quality measures are not included in the cost estimates in the WSCP, IPC has committed funds and indicated its willingness to implement water quality measures throughout the Snake River. For instance, the following measures have been implemented by IPC as required by the water quality certification and consent order for the Shoshone Falls, Upper Salmon Falls, Lower Salmon Falls, and Bliss projects:

• Annually assist ($15,000 per year) in further development and implementation of the Idaho Department of Environmental Quality's (IDEQ) middle Snake River watershed management plan/total maximum daily load (TMDL).

• Provide funding ($3,000,000 one time) for acquisition of spring resources on the middle Snake River to protect and enhance water quality and aquatic species habitats.

• Provide funding ($750,000 one time) for design, development, and construction of artificial wetlands, settling ponds, and other systems and facilities to prevent or reduce nutrients and sediments from entering the middle Snake River.

• Annually provide funding ($50,000 per year for ten years) to IDEQ for monitoring of long-term water quality conditions and changes.

Additionally, the following measures have not been implemented at this time but are proposed to be implemented after the FERC licenses are issued:

• Design, install, and operate equipment at the Upper Salmon Falls, Lower Salmon Falls, and Bliss projects to remove aquatic vegetation collected on trash racks.

• Maintain a minimum flow of 50 cfs in the North Channel at Upper Salmon Falls.

In addition, the IDEQ has issued a § 401 water quality certificate for the C.J. Strike Project, and as part of that certification, IPC is 1) providing $50,000 annually for TMDL development and, 2) after completion of the TMDL, will cooperate and implement measures to achieve IPC allocations.

IPC has also proposed several water quality measures to improve water quality in reaches associated with the HCC. As part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971), IPC has proposed to implement its DO load allocation identified in the draft Snake River-Hells Canyon TMDL by using reservoir aeration techniques in Brownlee

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Appendix 3–3. (Cont.)

Reservoir. Additionally, IPC has proposed to install and operate turbine-venting, or an equivalent oxygen supplementation system, at Brownlee Dam as a means to improve DO levels in Oxbow and Hells Canyon reservoirs and the tailwaters of Hells Canyon Dam. IPC has also proposed installing flow deflectors at Hells Canyon Dam to reduce TDG levels during periods of spill. Also, it is important to note that, while ODFW is not required to balance power and nonpower values, IPC and FERC are required to balance these values.

Response to Comment ODFW4-19

IPC does not believe that spawning and recruitment limitations for white sturgeon populations in the HCC are directly linked to the project operations. IPC believes that the construction and physical presence of the HCC has limited recruitment to specific reaches (for example, Oxbow and Hells Canyon reservoirs) and that changes in operations will not solve this problem. Further, IPC believes that there are few options to improve or restore habitats in those areas. The fact remains that construction of the projects converted riverine habitats to reservoir habitats, and the physical presence of the dams will continue to limit white sturgeon populations in those reaches. Downstream movements will continue to occur, especially in the larval stage, and any reproduction that may occur will continue to be removed - regardless of the daily operations and habitat available for spawning.

IPC believes that there are options to improve habitat that is potentially limiting sturgeon recruitment in the Swan Falls reach, however these options are not related to project operations. As emphasized in the TMDL process, this is a basin wide responsibility. IPC has continued to work with the IDEQ and ODEQ to develop measures that address IPC's assigned load allocations for improving water quality in the HCC and in reaches of the Snake River upstream of the HCC. However, IPC believes that further study is warranted in this reach to determine the effects of poor water quality on the early life stages of sturgeon. That is why IPC has proposed this evaluation as a measure in the WSCP. Below Hells Canyon, IPC does not believe there are serious habitat limitations for spawning and recruitment and believes the size and age structure and improvements occurring in the population, suggesting a recovery from early harvest regulations, support this conclusion.

Response to Comment ODFW4-20

IPC disagrees with ODFW’s claim that project operations below Hells Canyon Dam adversely affect white sturgeon recruitment. While the Instream Flow Assessment by Chandler et al. (2002) has shown operational impacts to early life stage modeled habitats during low flow water years, there is no evidence of this impact in actual recruitment. In fact, past studies have shown a positive trend in recruitment over the last 30 years (see IPC response to ODFW4-7 and ODFW4- 21).

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Appendix 3–3. (Cont.) Response to Comment ODFW4-21

IPC disagrees that habitat suitability is reduced for YoY, juvenile, and adult sturgeon life stages under Proposed Operations. According to Chandler et al. (2002) (Technical Report E.2.3-2 in the New License Application: Hells Canyon Hydroelectric Project), modeled habitat availability in the upper HC Reach for the YoY, juvenile, and adult life stages was not influenced greatly by discharge and therefore not impacted by Proposed Operations across any of the hydrologic years. In any one of the different flow years that were modeled, suitable conditions for reproduction are available to the sturgeon. Studies conducted by IPC and presented in Technical Report E.2.3-2 do not support ODFW's claim that there are significant energetic impacts to fish under fluctuating flows associated with peaking operations. IPC assessed the effects of project operations on the energetic expenditure and behavior of juvenile white sturgeon with two distinct evaluations. The first evaluation involved empirical field and laboratory studies to quantify energy expenditure of white sturgeon in their natural environment. The second evaluation involved integrating the empirical study results with the 2D hydraulic models and estimating areas of potential energy use as a means of habitat availability for sturgeon. For field studies, IPC monitored the movements and energy use of juvenile white sturgeon at two locations in the upper Hells Canyon Reach under three flow trials between September and November 2000. Results from this analysis found no relationship between river flow or light intensity and activity level (i.e., energy use measured as oxygen consumption (kcal/kg/hr)) of juvenile white sturgeon. Results from this evaluation suggested that difference in energy use among the three trials was related to temperature. This finding is especially pertinent to the September trial when there was extreme daily load following fluctuations. Modeling habitat availability from low potential energy use areas suggested more area available to juvenile sturgeon then estimated using HSC criteria and traditional WUA calculations.

Given that the Hells Canyon-Lower Granite sturgeon population shows good recruitment trends, it appears that load following in the upper reaches of the free-flowing section does not have a significant impact on natural production. Figure 1 shows the timing of spawn intervals (10−18 °C) and spring runoff available to the Hells Canyon-Lower Granite sturgeon population. Based on temperature and flow data between 1990 and 2000, which includes drought to record high flows, peak spring flows and spawn intervals below the Salmon River confluence coincide each year. In the upper portion of the Hells Canyon-Lower Granite reach (Hells Canyon Dam to the Salmon River), peak spring flows (when available) coincide with spawn intervals. During low- flow years, peak spring flows are typically not available to the Snake River as a result of water management practices (refilling of storage reservoirs for agriculture) in the upper basin. However, even at low flows of 5,000 cfs in the upper section of the reach, suitable spawning conditions are still met. Spawning habitat is the most available habitat of any sturgeon life stage in this reach (Technical Report E.2.3-2 in the New License Application: Hells Canyon Hydroelectric Project). In any one of these years, suitable conditions for reproduction are available to the sturgeon population within the Hells Canyon-Lower Granite reach.

27 Snake River White Sturgeon Conservation Plan Idaho Power Company

Appendix 3–3. (Cont.)

Spawn period below Salmon River confluence Flow at Anatone Gauge (below Salmon River) Spawn period between Hells Canyon Dam and Salmon River Flow at Hells Canyon Dam

160 1991 1992 1993 1994 1995 140 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct

160 1996 1997 1998 1999 2000 140

Mean Daily FlowMean Daily (kcfs) 120 100 80 60 40 20 0 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Month Figure 1. Mean daily flow and spawn periods for white sturgeon in the Hells Canyon-Lower Granite reach of the Snake River.

Response to Comment ODFW4-22

As discussed in comment 4-19, IPC does not believe that flow related issues such as operations of the HCC are limiting white sturgeon in these reaches and minimum flows should not be an issue for sturgeon. As discussed in the WSCP, other factors dominate the present abundance of sturgeon in these reaches. Below Swan Falls dam, IPC believes that improvements to water quality are essential before recovery can be made, and ODFW seems to concur with this conclusion as stated in comment 4-24. Below Hells Canyon Dam, there appears to be strong annual recruitment and the population represents a stronghold in the Snake River. For Oxbow and Hells Canyon, IPC continues to assert that any reproduction that may occur is lost from the system because of the short segments. Problems in these two reservoirs relate more to the physical location and presence of the dams, and operations or minimum flows will not resolve this problem. ODFW is correct regarding the results of IPC studies in the Oxbow bypass and the 100 cfs minimum flow and the spawning habitat in the tailwater of Oxbow powerhouse increasing linearly with flow. However, IPC believes that the habitat in the Oxbow tailwater presently provides sufficient flow for spawning - especially for the low number of individuals

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Appendix 3–3. (Cont.) present in the reach - and that increased flows in the Oxbow bypass will not resolve the primary limiting factors for white sturgeon in this reach.

Response to Comment ODFW4-23

The proposed measure of monitoring success of white sturgeon spawning and early life stage survival is not explicitly dependent upon a translocation measure. However, in the case of the Oxbow and Hells Canyon reservoirs, IPC believes this to be true. During the 1999 spawning period, IPC deployed substrate mats in the tailraces of Brownlee and Oxbow dams and no eggs were collected from this effort. IPC believes any further attempts to evaluate spawning success would first require transplanting (translocation) sufficient numbers of reproductive adults in order to increase the spawning population given few sturgeon remain in these reservoirs.

Spawning conditions for white sturgeon have also been evaluated below Oxbow Dam by Myers and Chandler (2001). However, for reasons described in Section 9.7 of the WSCP, IPC has not proposed translocation to Oxbow and Hells Canyon reservoirs. In addition, ODFW has also repeatedly stated their opposition to translocation to the Oxbow and Hells Canyon pools in comments to the WSCP and draft License Application for the HCC. Rather, periodic stock assessments proposed for Oxbow and Hells Canyon reservoirs would be better suited to evaluate future recruitment.

Response to Comment ODFW4-24

ODFW states that the Swan Falls - Brownlee reach is one of the most degraded reaches of the Snake River and that IPC should be implementing measures to improve water quality conditions associated with the HCC and include measures that improve water quality beyond those required in the draft Snake River - Hells Canyon TMDL. IPC has proposed several water quality measures to improve water quality in reaches associated with the HCC. As part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971), IPC has proposed to implement its DO load allocation identified in the draft Snake River-Hells Canyon TMDL by using reservoir aeration techniques in Brownlee Reservoir. Additionally, IPC has proposed to install and operate turbine-venting, or an equivalent oxygen supplementation system, at Brownlee Dam as a means to improve DO levels in Oxbow and Hells Canyon reservoirs and the tailwaters of Hells Canyon Dam. IPC has also proposed installing flow deflectors at Hells Canyon Dam to reduce TDG levels during periods of spill.

IPC has indicated a willingness to work with IDEQ and ODEQ to develop measures that address IPC's assigned load allocations for improving water quality in the HCC. Both the ODEQ and IDEQ have determined through their analyses in the draft Snake River-Hells Canyon TMDL process that reductions in inflowing nutrient and organic matter, along with IPC's proposed level of aeration, should result in compliance with DO standards for Brownlee Reservoir (IDEQ and

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Appendix 3–3. (Cont.)

ODEQ 2001). ODFW’s comment fails to recognize the responsibility of other parties for improving water quality in the Snake River. The ODFW should be recommending that ALL parties responsible for degrading water quality within these reaches develop measures to meet their load allocations for improving water quality and beneficial use.

Response to Comment ODFW4-25

IPC is proposing to investigate contaminant levels and their effects on sturgeon embryos in the Swan Falls to Brownlee reach as described in Section 8.6.1. This includes evaluation of bioaccumulated contaminant concentrations (metals, organochlorine pesticides, and PCBs) resulting from parental contribution, river bottom de-adhesion media, and suspended solids in river water.

Response to Comment ODFW4-26

The effects of project operations on white sturgeon habitats have been evaluated (instream flow assessment) below Swan Falls Dam (Chandler and Lepla 1997). Based on movements of telemetered spawners, collection of eggs and larvae, and instream flow assessment, suitable spawning conditions are provided in the canyon corridor below Swan Falls Dam. Due to the high gradient nature of the river corridor below Swan Falls Dam, spawning habitat in the Swan Falls reach is not limited by flow. IPC has proposed measures to improve water quality in Brownlee Reservoir in the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971), as well as further investigation of the effects of degraded water quality on early life stages in the riverine section of this reach. As indicated in the WSCP, any measure to improve white sturgeon productivity within this reach likely will first depend on improving water quality.

Response to Comment ODFW4-27

IPC does not support initiating the water quality assessment on early life survival for white sturgeon in the Swan Falls reach until this measure has been reviewed and accepted by FERC for inclusion in a new project license for the HCC.

Response to Comment ODFW4-28

The WSTAC recommended translocation of reproductive-sized sturgeon as one potential option for increasing spawner abundance and future population productivity in the Swan Falls - Brownlee reach. The WSTAC also acknowledged that significant improvements in water quality

30 Snake River White Sturgeon Conservation Plan Idaho Power Company

Appendix 3–3. (Cont.) would need to occur before this measure could be implemented. IPC has proposed several water quality measures to improve water quality in reaches associated with the HCC. As part of the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971), IPC has proposed to implement its DO load allocation identified in the draft Snake River-Hells Canyon TMDL by using reservoir aeration techniques in Brownlee Reservoir. Additionally, IPC has proposed to install and operate turbine-venting, or an equivalent oxygen supplementation system, at Brownlee Dam as a means to improve DO levels in Oxbow and Hells Canyon reservoirs and the tailwaters of Hells Canyon Dam. IPC has also proposed installing flow deflectors at Hells Canyon Dam to reduce TDG levels during periods of spill. IPC has also proposed implementing or implemented other water quality measures upstream. (See IPC response to ODFW4-18.)

IPC has indicated a willingness to work with IDEQ and ODEQ to develop measures that address IPC's assigned load allocations for improving water quality in the HCC. Both the ODEQ and IDEQ have determined through their analyses in the draft Snake River-Hells Canyon TMDL process that reductions in inflowing nutrient and organic matter, along with IPC's proposed level of aeration, should result in compliance with DO standards for Brownlee Reservoir (IDEQ and ODEQ 2001). Although water quality improvements may take time, translocation should not be dismissed as a potential option for future consideration.

Response to Comment ODFW4-29

IPC agrees that any future actions, including translocation, should not threaten the viability and persistence of strong hold populations such as the Hells Canyon - Lower Granite and Bliss - C.J. Strike sturgeon populations (guiding principle of the WSCP). In addition, reestablishing natural recruitment within depressed reaches will depend on the degree to which limiting factors for sturgeon can be effectively addressed.

Response to Comment ODFW4-30

The WSTAC recommended (which does not infer consensus) IPC consider experimental conservation aquaculture as one potential option and therefore it is included within the WSCP only as a potential option for future consideration in two reaches. IPC did not propose hatchery supplementation for other reaches recommended by the WSTAC for reasons described in Sections 9.3 and 9.7. IPC also understands that the decision of whether to develop a conservation aquaculture program in the Swan Falls - Brownlee reach would be made by the IDFG and ODFW. IPC has proposed measures, committed funds and indicated its willingness to implement water quality measures throughout the Snake River (see IPC response to ODFW4-18).

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Appendix 3–3. (Cont.) Response to Comment ODFW4-31

Wittmand-Todd et al. (2001) evaluated a full range of possible passage alternatives and concluded Capture and Transport would be the most feasible and practical option for passing sturgeon at the HCC. Any additional evaluations would still likely conclude Capture and Transport as the most practical solution. ODFW says that fish locks at Bonneville Dam on the Columbia River were used extensively by white sturgeon and thus recommends that Idaho Power should further investigate their biological effectiveness. Operation of the Bonneville locks was discontinued because of the inefficiency for passing salmon and steelhead and lack of interest to pass sturgeon at that time. IPC questions why the fish locks at Bonneville Dam have not been re- activated for sturgeon. It is also important to note that operation of the Bonneville locks was time consuming and labor intensive. It would appear that fish locks at Bonneville Dam are not cost effective for passing sturgeon even from the most abundant sturgeon population in North America when compared to other alternatives. ODFW has used capture and transport techniques to mitigate for loss of passage and was able to document high survival and effectiveness. IPC questions why ODFW considers capture and transport techniques as acceptable means for passing white sturgeon around hydroelectric projects on the Columbia River while not acceptable for passing white sturgeon at Snake River hydroelectric projects operated by IPC? As to Oregon's fish passage statute, in the Federal Power Act Congress has preempted it to the extent that it purports to apply to federally licensed and regulated hydropower projects.

Response to Comment ODFW4-32

IPC disagrees with ODFW's claim that dam removal will be necessary to prevent the extirpation of white sturgeon populations throughout the middle Snake River. Degraded water quality is one of the major factors affecting white sturgeon. ODFW's comment ignores several measures proposed by IPC for improvement of water quality, which will benefit white sturgeon. IPC has committed funds and indicated its willingness to implement water quality measures throughout the Snake River (see IPC response to ODFW4-18). Translocation can also be used as an effective tool to rebuild population productivity (Section 8.6.1) and/or provide access to suitable spawning habitats (Section 8.5.1). IPC has evaluated passage options and concluded “Capture and Transport” is the most feasible option at this time. Any further evaluations will likely still conclude Capture and Transport as the most feasible option.

Response to Comment ODFW4-33

IPC does not believe that land acquisition and riparian habitat enhancement in tributaries will benefit white sturgeon enough to address the primary limiting factors. While they may provide measurable benefits to fish populations within those tributaries, the geographic scope required for changes to affect conditions facing white sturgeon in the mainstem Snake River is much larger and encompasses the entire Snake River basin upstream of the HCC. While IPC has

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Appendix 3–3. (Cont.) proposed tributary enhancement measures and some land acquisition associated with the HCC license for other resources. IPC continues to believe that participation in the ongoing TMDL's associated with the mainstem Snake River will be the best way to contribute to the necessary habitat and water quality enhancements that will specifically benefit white sturgeon. See IPC’s response to ODFW4-18 for a list of some water quality measures implemented, or proposed to be implemented, by IPC.

Response to Comment ODFW4-34

As discussed in IPC’s response to ODFW4-19, IPC does not believe that spawning and recruitment limitations for white sturgeon populations in the HCC are linked to the operations of the HCC. The Population Viability Analysis indicated water quality, low spawner abundance and sturgeon export were limiting factors in Oxbow and Hells Canyon reservoirs. The Brownlee- Oxbow and Oxbow-Hells Canyon reaches are two relatively short river segments in the Snake River. A common observation in short reaches of both the Mid-Snake and Hells Canyon complexes has been little or no detectable presence of sturgeon. Not only does the relatively close spacing of adjacent dams limit the amount of available habitat, but the short distance between dams probably contributes more to downstream losses of sturgeon than do longer reaches, particularly for sturgeon in early life stages. White sturgeon larvae are planktonic and can drift long distances in river currents. In addition, the reservoirs may also be affecting recruitment success of sturgeon by increasing egg and larval predation by species associated with reservoir environments. IPC does not believe changes in project operations below Oxbow or Brownlee dams for spawning will improve recruitment of sturgeon to these reaches for reasons discussed above and in Section 9.7 of the WSCP. The flow regime below Hells Canyon Dam presently appears optimal (see IPC’s response to ODFW4-21) for white sturgeon, and the present population structure of strong annual recruitment supports that conclusion. As for the Swan Falls reach, flows do not appear to be a limiting factor for white sturgeon. Until water quality conditions improve, (as stated in ODFW4-24), the current trend in abundance within this reach will likely not improve. IPC intends to comply with all valid and enforceable state and federal laws to the extent of their applicability.

Response to Comment ODFW4-35

ODFW misinterprets and confuses IPC's response. IPC made two points in its response. First, under Idaho law, IPC cannot obtain or acquire water for the purpose of improving water quality or for any other resource or aesthetic instream use. Second, the water resources of the upper Snake River basin are overappropriated and that fact, together with the U.S. Bureau of Reclamation's efforts to acquire and/or lease Idaho storage water for downstream augmentation purposes, results in little, if any, storage water being available for other purposes, such as hydropower. ODFW responds that IPC can obtain water for hydropower use and argues that water from upper Snake River reservoirs remains available, either through storage space

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Appendix 3–3. (Cont.) acquisition or rental, for such purposes. IPC agrees that Idaho law allows IPC to acquire water, through purchase or rental, for hydropower purposes. But that is neither responsive to ODFW's initial comment nor does it change the shortage of water in the upper Snake River basin. IPC stands by its response: IPC cannot obtain water for the purpose of increasing flows in the middle Snake River.

Response to Comment ODFW4-36

IPC assumes ODFW meant to say that the “recommended” mitigation measures should not read increase flow or restore/protect riparian but rather are two separate measures. Clarification to Section 7 - Recommended Measures by the WSTAC has been made.

IPC disagrees with ODFW's statement that no measures have been proposed for white sturgeon. IPC has proposed translocation as a potential means for increasing population abundance and productivity in the Swan Falls - Brownlee reach. IPC has proposed conducting a water quality assessment on early life stage survival of white sturgeon. Measures to improve water quality conditions for DO and TDG have been proposed in the New License Application: Hells Canyon Hydroelectric Project (FERC No. 1971) for below Hells Canyon Dam and reservoirs of the HCC, which will also benefit sturgeon. In addition, IPC has implemented, or proposed to implement, other water quality measures further upstream. (See IPC’s response to ODFW4-18.)

ODFW’s comment in general seem to attribute to IPC poor water quality, irrigation withdrawal, sport fishing, and other factors that have and continue to negatively impact Snake River white sturgeon, but over which IPC has no control. IPC should not be required to mitigate for impacts over which it has no control. Also, it is important to note that, while ODFW is not required to balance power and nonpower values, IPC and FERC are required to balance these values.

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