Feasibility of Reintroduction of Anadromous Fish Above or Within the Hells Canyon Complex

James A. Chandler Editor

Technical Report Appendix E.3.1-2 December 2001 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company

Evaluation of Reintroduction Alternatives

James A. Chandler Fisheries Biologist

Don Chapman BioAnalysts, Inc.

Technical Report Appendix E. 3.1-2 Feasibility of Reintroduction of Anadromous Fish above or within the Hells Canyon Complex

Chapter 11 December 2000 Revised July 2003 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company

Idaho Power Company Chapter 11: Reintroduction Alternatives

TABLE OF CONTENTS

Table of Contents ...... i

List of Tables...... iv

List of Figures ...... vi

1. Introduction ...... 1

2. Methods...... 1

2.1. Downstream Migration Survival...... 1

2.1.1. Free-Flowing River Segments...... 2

2.1.2. Reservoir Segments...... 4

2.1.3. Brownlee Reservoir...... 4

2.2. Estimates of Smolt-to-Adult Returns ...... 6

2.3. Estimates of Required Escapement...... 7

2.3.1. Low Required Escapement (LRE) ...... 7

2.3.2. High Required Escapement (HRE) ...... 8

2.4. Reintroduction Scenario Evaluations...... 8

2.4.1. Scenario 1: Free-Flowing River Passage ...... 8

2.4.2. Scenario 2: Passage at Hells Canyon Dam and Oxbow Dam ...... 9

2.4.3. Scenarios 3A and 3B: Passage of Adults at Brownlee Dam—1957 Subbasin Availability ...... 9

2.4.4. Scenario 4: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Upper Reservoir Collection ...... 10

2.4.5. Scenarios 5A and 5B: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Collection and Transport at Brownlee Dam ...... 10

2.4.6. Scenarios 6A and 6B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam...... 10

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2.4.7. Scenarios 7A and 7B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam, Collection and Transport at Brownlee Dam 11

2.4.8. Scenario 8A and 8B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, 100% Bypass at Brownlee Dam ...... 11

2.4.9. Scenarios 9A and 9B: Collection at C.J. Strike Dam, 100% Bypass at Brownlee Dam...... 11

3. Results ...... 11

3.1. Free-Flowing River Scenario ...... 12

3.2. Oxbow and Hells Canyon Scenarios...... 12

3.2.1. Scenario 2: Passage at Hells Canyon Dam and Oxbow Dam ...... 12

3.3. Upstream of Brownlee Dam Scenarios ...... 13

3.3.1. Scenarios 3A and 3B: Passage of Adults at Brownlee Dam—1957 Subbasin Availability ...... 13

3.3.2. Scenario 4: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Upper Reservoir Collection ...... 14

3.3.3. Scenarios 5A and 5B: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Collection and Transport at Brownlee Dam ...... 14

3.4. Upstream of Swan Falls Dam Scenarios...... 15

3.4.1. Scenarios 6A and 6B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam...... 15

3.4.2. Scenarios 7A and 7B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam, Collection/Transport at Brownlee Dam ...... 16

3.4.3. Scenarios 8A and 8B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, 100% Bypass at Brownlee Dam ...... 16

3.4.4. Scenarios 9A and 9B: Collection at C.J. Strike Dam, 100% Bypass at Brownlee Dam...... 16

4. Discussion ...... 17

4.1. Ability to Maintain Production Potential ...... 17

4.2. Assumptions...... 18

4.2.1. Survival Estimates...... 18

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4.2.2. Smolt-to-Adult Returns and Required Escapement Assumptions ...... 18

4.2.3. The “No-Fishing” Assumption...... 21

4.3. Subbasin Smolt Production...... 21

4.4. Hatchery Supplementation ...... 23

4.5. Costs of Reintroduction...... 24

4.5.1. Facilities ...... 24

4.5.2. Operations ...... 25

4.6. Feasibility of Reintroduction...... 25

4.6.1. Goals of Reintroduction ...... 25

4.6.2. Recovery and the Evolutionarily Significant Unit ...... 26

4.6.3. Ecosystem Recovery ...... 27

4.6.4. Harvest Potential ...... 28

4.6.5. Marine-Derived Nutrients ...... 29

5. Summary and Conclusions...... 30

6. Literature Cited ...... 31

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LIST OF TABLES

Table 1. Number of spring/summer chinook and steelhead PIT-tagged and released at the Salmon River trap near Riggins and at the Snake River trap near Lewiston, recovered at four downstream dams (Lower Granite, Little Goose, Lower Monumental, and McNary), and rate of recovery. Data are from Buettner and Brimmer (1994, 1995, 1996, 1998)...... 39

Table 2. Description of reintroduction scenarios evaluated...... 40

Table 3. Mortality coefficients and survival estimates of spring chinook salmon, steelhead, and fall chinook salmon for different reaches of the Snake River...... 41

Table 4. Required adult escapement of spring chinook necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions...... 43

Table 5. Required adult escapement of steelhead necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions...... 43

Table 6. Required adult escapement of fall chinook necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions...... 43

Table 7. Survival of spring chinook smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 44

Table 8. Number of spring chinook smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 45

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Table 9. Number of spring chinook adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 46

Table 10. Survival of steelhead smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 47

Table 11. Number of steelhead smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 48

Table 12. Number of steelhead adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 49

Table 13. Survival of fall chinook smolts from potential mainstem production areas upstream of Hells Canyon Dam arriving at the Lower Granite Dam tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 50

Table 14. Number of fall chinook smolts from potential mainstem production areas upstream of Hells Canyon Dam arriving at the Lower Granite Dam tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 51

Table 15. Number of fall chinook adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 52

Table 16. Estimated facility construction and annual operation and maintenance (O&M) costs (in millions of dollars) for each of the reintroduction scenarios. Costs do not include the operational costs associated with the 89-ft or 21-ft Brownlee Reservoir drawdown options discussed in the text. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam...... 53

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LIST OF FIGURES

Figure 1. Survival of spring chinook, steelhead, and fall chinook smolts from river kilometers of the Snake River where mainstem smolt outmigration would begin to the tailrace of Lower Granite Dam under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir...... 54

Figure 2. The relationship between location (river kilometer) of production areas and the proportion of adult returns to Hells Canyon Dam to required adult escapement under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir, under low and high smolt-to-adult returns (LSAR and HSAR), and under low and high assumptions of required escapement (LRE and HRE). Letters above refer to the following subbasins and locations along the mainstem Snake River: A = Pine Creek, B = Wildhorse River, C = Powder River, D = Weiser River, E = Bruneau River, F = Salmon Falls Creek, G = Rock Creek, H = Walters Ferry, I = Below C.J. Strike Dam, J = Above C.J. Strike Dam...... 55

Figure 3. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from Pine Creek under low and high assumptions for required escapement (LRE and HRE, horizontal lines) for each reintroduction scenario...... 56

Figure 4. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Wildhorse River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario...... 57

Figure 5. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of number of adults required to maintain smolt production from the Powder River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario...... 58

Figure 6. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of number of adults required to maintain smolt production from the Weiser River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with

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transportation (T) and without adult transportation for each reintroduction scenario...... 59

Figure 7. Estimated adult returns of fall chinook to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Walters Ferry Reach (A), above Swan Falls Reach (B), and above C.J. Strike Reach (C) of the Snake River under low and high assumptions for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario...... 60

Figure 8 Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Bruneau River under low and high assumptions for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario...... 61

Figure 9. The relationship between location (river kilometer) of production areas and the proportion of adult returns at Lower Granite Dam to required adult escapement for spring chinook under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir, under assumptions using combinations of low and high smolt-to-adult returns (LSAR and HSAR) and low and high estimates of required escapement (LRE and HRE), and smolts per spawned estimates under LSAR and HSAR conditions using Petrosky et al. (2001)...... 62

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1. INTRODUCTION

In this chapter, we evaluate a number of scenarios for reintroducing anadromous fish to the Snake River basin. We base our evaluations for each scenario on estimated potential adult returns to Hells Canyon Dam from subbasin smolt production estimates we developed in Chapter 7 (Chapman and Chandler 2001a) and presented in Chapter 8 (Chapman and Chandler 2001b). In doing so, we assume that smolts (from production numbers that we provided from estimates of fully seeded basins in Chapter 8 [Chapman and Chandler 2001b]) will enter the mainstem Snake River and arrive at the tailrace of the Lower Granite Project either by transportation or by some combination of downstream passage. Therefore, the specific criteria for each evaluation are 1) the estimated number of smolts from the subbasin or mainstem river section to reach the Lower Granite tailrace and 2) the corresponding adult returns.

We compare the estimates of adult returns with estimates of escapement that would be required to maintain the subbasin smolt production estimates. Although we do not evaluate all subbasins or every potential scenario, we present and discuss a range of alternatives that cover the requisite factors and considerations for any reintroduction alternative. For each scenario, we also relate adult returns to the estimates of construction costs for passage facilities presented in Chapter 9 (Aurdahl et al. 2001). However, we do not consider the specific actions necessary in each subbasin for reintroduction to succeed. These actions include irrigation screening and construction of bypass or collection facilities in the subbasins. We also do not consider predation and other mortality factors that could occur within the subbasin.

2. METHODS

2.1. Downstream Migration Survival

We wanted to estimate the survival of juvenile salmon and steelhead that pass downstream through free-flowing segments of rivers and reservoirs. This estimate would permit us, in part, to adjust estimated potential smolt outputs from various subbasins upstream of Hells Canyon Dam to account for mortality between subbasins and points downstream. By adjusting for survival through the Lower Granite Project, it is also possible to use smolt-to-adult returns (SARs) calculated from Lower Granite Dam to the mouth of the Columbia River and to Hells Canyon Dam. The mortality adjustment, if calculated as a loss rate per kilometer, also estimates arrivals of smolts from subbasins that lie varied distances upstream of Hells Canyon Dam. As a preliminary step, we tabulated river miles and river kilometers of various sites upstream of the mouth of the Snake River, as well as stream kilometers upstream of the Lower Granite reservoir and tailrace.

To calculate the relationship between time and distance, it is useful at this point to consider Ricker’s (1958) discussion of the relationship between survival and time. He stated:

Hells Canyon Complex Page 1 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

If the number of deaths in a small interval of time is at all times proportional to the number of fish present at that time, the fraction, which remains at time t, of the fish in a population at the start of a year (t = 0) is:

-it Nt / N0 = e .

The parameter i is called the instantaneous mortality rate. If the unit of time is 1 year, then at the end of the year (when t = 1):

-i N1 / N0 = e .

But N1 / N0 = s = (1 – a), where s = survival rate and a = mortality rate, hence

-i (1 – a) = e , or i = –loge(1 – a);

hence the instantaneous mortality rate is equal to the natural logarithm (with sign changed) of the complement of the annual (actual) mortality rate.

Thus, i equals the negative natural log of the survival rate. The instantaneous mortality rate for one year can be divided into any number of parts. For example, the year can be divided by 365 to calculate i for one day. In this report and its accompanying tables, we refer to i as the “mortality coefficient.” Instead of using time, we use distance. For example, i for 100 kilometers (km) can be divided into 100 parts, resulting in a mortality coefficient for 1 km.

To estimate the numbers of smolts from each subbasin or river reach upstream of Hells Canyon Dam that would arrive at the Lower Granite tailrace, we calculated mortality coefficients and survival rates for each species in each river or reservoir segment.

2.1.1. Free-Flowing River Segments

Buettner and Brimmer (1994, 1995, 1996, 1998) provided four years of data that allowed us to estimate the mortality rates of spring/summer chinook and steelhead smolts per unit of distance. They PIT-tagged smolts at the Salmon River trap, near Slate Creek, and at the Snake River trap near the upstream end, or head, of Lower Granite Reservoir. The distance between the two trap locations equals about 180 km. Tags were interrogated at four sites (Lower Granite, Little Goose, Lower Monumental, and McNary dams). The ratio of the total percentage of fish tagged at each trap and recovered at the four downstream dams provides an estimate of survival over the 180-km reach between the two traps.

To use the survival estimate prepared from detection rates, we assumed that fish PIT-tagged at the two traps behaved similarly from the location of the Snake River trap to points of subsequent tag detection.1 We prepared separate estimates for wild steelhead, hatchery steelhead, wild

1 The fish captured and tagged at the Salmon River trap consisted of fish from hatcheries and wild production areas upstream of that trap. The fish captured and tagged at the Snake River trap consisted of juveniles from points upstream of the Salmon River trap and from tributaries and hatcheries downstream of the Salmon River trap.

Page 2 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives spring/summer chinook, and hatchery spring/summer chinook. We then calculated survival estimates for each species. The estimated mean survival for spring/summer chinook over the four years—1993, 1994, 1995, and 1996—equaled 0.88 (Table 1). A similar calculation for steelhead yielded a survival estimate of 0.92. We consider these estimates to be reasonably representative of survival through the free-flowing Salmon and Snake rivers over 180 km. The estimates comport with Raymond (1979), who used somewhat less-robust techniques to estimate a 0.89 survival of wild chinook smolts between Riggins and Ice Harbor Dam in 1966–1968.

The estimated survival rate for spring/summer chinook between the Salmon River and Snake River traps (180 km) equals 0.88. Taking the natural log of this survival rate, we calculate the mortality coefficient as –0.128.2 A similar calculation for steelhead yields a mortality coefficient of –0.0834. These estimates yield respective mortality coefficients per kilometer of 0.000722 and 0.000444.

No data exist on the survival rates of sockeye through the free-flowing Salmon or Snake rivers. We assumed that sockeye would survive at the same rate as spring/summer chinook.

Williams and Bjornn (1997) estimated the survival of juvenile fall chinook from Pittsburg Landing to the Lower Granite tailrace in 1995. They also estimated survival through the Little Goose and Lower Monumental projects. They reported a 0.67 mean survival rate for naturally produced juveniles. For hatchery fish, they reported a 0.63 survival rate from Pittsburg Landing through the Lower Granite Project. We averaged these survival rates as 0.65. Williams and Bjornn (1998) obtained estimates of survival through the same reach in 1996 and calculated the survival rates of natural and hatchery fall chinook as 0.66 and 0.32, respectively. Finally, Muir et al. (1999) reported survival rates of natural fall chinook from Pittsburg Landing to the Lower Granite tailrace as 0.57 (for early releases), and for hatchery fish as 0.62 (early) to 0.14 (late). We adopt a conservative survival rate of 0.65 as fairly representing the survival of subyearling fall chinook juveniles from Pittsburg Landing to the Lower Granite tailrace.

To separate Lower Granite Project effects from the overall reach effects, thus obtaining survival through the free-flowing Snake River, we used the Williams and Bjornn (1997) estimate of survival through the Little Goose Project for fish released at Pittsburg Landing. The mean combined survival rate for natural (0.84) and hatchery (0.84, 0.84, and 0.71) fish equals 0.81. The Little Goose Project is only slightly shorter (48 km) than the Lower Granite Project (52 km), so we assumed that survival through Little Goose would represent survival through the Lower Granite Project.

We divided overall reach survival (0.65) by estimated survival through the Lower Granite Project (0.81), obtaining an estimated survival rate of 0.80 for the free-flowing Snake River over a distance of 121 km (Pittsburg Landing to the head of Lower Granite Reservoir). This 0.80 survival rate converts to an arithmetic mortality rate of 0.20 over the reach and a mortality coefficient per kilometer of 0.00185.

2 The mortality coefficient can exceed 1.0. For example, a survival rate of 0.30 equates to a mortality coefficient of –1.2.

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These survival estimates for each species were used to model survival through free-flowing sections of the Snake River upstream of Hells Canyon Dam.

2.1.2. Reservoir Segments

Williams et al. (2001) reported survival rates for steelhead and chinook salmon smolts that migrated through the Lower Granite reservoir and dam (52 km). Data were available from 1994, 1995, and 1996 for steelhead, and from 1993, 1994, and 1995 for spring/summer chinook salmon. The mean survival rates for steelhead and spring/summer chinook equaled 0.91 and 0.92, respectively. In 1996, spring/summer chinook smolts survived from the Lower Granite tailrace to the Little Goose tailrace at a rate of 0.92; hatchery steelhead, at a rate of 0.93 (Smith et al. 1998). No data exist for sockeye survival through this or any other reach in the Snake River. We assumed that sockeye would survive at the same rate as that of spring chinook. As we noted in Section 2.1.1., we estimated the survival rate of juvenile fall chinook through the Lower Granite Project as 0.81.

We converted the foregoing arithmetic survivals to the following mortality coefficients:

Species Mortality Coefficient (per km) Spring chinook –0.001603 Steelhead –0.00181 Fall chinook –0.00405 Sockeye –0.001603 (assumed to be the same as that for spring chinook)

We used these mortality coefficients to model survival through reservoirs upstream of Hells Canyon Dam, with the exception of Brownlee Reservoir. We must emphasize that, by applying these survival estimates, we are assuming that survival (turbine passage, bypass, and spill collectively) through the projects upstream of Hells Canyon would be comparable to survival at Lower Granite Dam under the conditions we cited earlier. This assumption further implies that those bypass facilities would have efficiencies comparable to the facilities at Lower Granite Dam.

2.1.3. Brownlee Reservoir

Raleigh and Ebel (1968) described the limnology of Brownlee Reservoir. They also described the results of trapping and marking juvenile spring and fall chinook in the Snake River just downstream of the Weiser River. They reported the numbers of juveniles that passed scoop traps set up to capture fish downstream of Brownlee Dam, based on the estimated efficiency of the traps. With estimates of recruitment to the reservoir and the numbers of fish that reached Brownlee tailrace, they were able to estimate the survival rates of fish that passed through Brownlee Reservoir and reached the dam in the years 1963 to 1965. The most useful data were derived during the 1963 and 1964 migration years. In 1963, the maximum reservoir drawdown was only 21 feet (ft). In 1964, the maximum drawdown increased to 89 ft.

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Unfortunately, the subyearlings on which Raleigh and Ebel (1968) based their 1964 survival rate consisted of both wild and hatchery juveniles. The 0.85 survival estimate for 1964 subyearling passage through the Brownlee Project was 67% higher than the estimated 0.51 survival rate of yearling spring chinook. More recent studies of relative survival rates consistently indicated higher survival rates for yearling chinook than for subyearlings, which move downstream in late spring and early summer when water temperatures are higher and predators are presumably more active. We elected to apply the ratio of subyearling survival to yearling survival (0.82), as obtained for wild fish in 1963, to the survival rate of wild yearlings (0.51) in 1964. Thus, the estimated survival rate of wild subyearlings in 1964 is calculated as 0.82 × 0.51 = 0.42. For comparison, we note that in Muir et al. (1996) the ratio of survival of naturally produced subyearlings to survival of wild yearlings through the Little Goose Project in 1995 was calculated as 0.84 ÷ 0.88 = 0.95. One might expect a higher survival rate for subyearlings, relative to yearlings, through the Little Goose Project, the second project that subyearlings encounter on the lower Snake River, than would have occurred through the Brownlee Project.

Spring and fall chinook survived at rates of 0.17 and 0.14, respectively, in 1963. In 1964, with over a fourfold increase in drawdown (21 ft to 89 ft), the respective estimated survival rates rose to 0.51 (Raleigh and Ebel 1968) and 0.42 (our estimate from the preceding paragraph).

We converted the foregoing arithmetic survivals to project the following mortality coefficients:

Mortality Coefficients Species 1963 1964 Spring chinook –1.772 –0.673 Steelhead Assumed to be the same as that for spring chinook Fall chinook –1.966 –0.868

The mortality coefficients apply to the reach between the locations of the scoop traps (used to capture fish for estimates of recruitment to the reservoir) and the tailrace of Brownlee Dam. The traps were located 5 miles (mi) downstream of the Weiser River. Thus, we can calculate the following mortality coefficients per kilometer:

Mortality Coefficients Species 1963 1964 Spring chinook –0.0208 –0.00792 Steelhead Assumed to be the same as that for spring chinook Fall chinook –0.0231 –0.0102

These survival estimates account only for survival to Brownlee Dam. They do not account for the mortality of fish traveling to the tailrace of Brownlee Dam through either the spillway or the turbines. To estimate survival from Brownlee Dam to the Brownlee Dam tailrace, we calculated blade strike probabilities for different lengths of fish using equations developed by Von Raben

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(1957) and described by Cada (1990), specifications of the Francis turbines, and the configuration of the five generating units in the Brownlee Powerhouse. Blade strike does not necessarily imply mortality (Von Raben 1957). However, we assumed that the probability of blade strike was equal to the probability of mortality. In addition to turbine mortality, we calculated pressure-induced mortality for each turbine, based on the configuration of the powerhouse for Brownlee Dam (Bell 1990). We treated turbine and pressure mortality as concurrent sources of mortality and combined (sum minus the product) as a total estimate of mortality (Ricker 1958).

We used the average mortality of fish that were 125 millimeters (mm) and 200 mm long passing through Brownlee Dam’s fifth generating unit, which includes the largest Francis turbine at the project. This mortality rate equates to a turbine passage survival estimate of 0.69. The survival estimates for the smaller Francis turbines of Units 1 through 4, using the same approach, was 0.59. In addition, we assumed that survival through spill would be 100% and estimated the number of fish that would pass through spill and turbines as a proportion of the total volume of water that is either spilled or passed through the turbines during the months April through June in a median water year. Using the water year 1995 to represent median conditions, approximately 5.2% of the total volume of water is spilled at Brownlee Dam. Combining spill with turbine passage equates to a Brownlee Project survival rate of 0.71.

2.2. Estimates of Smolt-to-Adult Returns

With survival calculations for each segment, and the number of smolts potentially produced in each subbasin or river reach, we could estimate the number of smolt arrivals at the tailrace of the Lower Granite Project under various reintroduction scenarios. With those arrivals calculated, we applied SARs from smolts at the Lower Granite tailrace to adult returns at the mouth of the Columbia River extant in the early 1990s and early 1960s (Raymond 1979, Petrosky et al. 2001). We adjusted those returns by a multiplier of 0.96 per dam for 9 interdam losses (0.969) between the Columbia River mouth and Hells Canyon Dam. The adjustment thus included interdam loss between passage at Lower Granite Dam and at Hells Canyon Dam. We did not account for potential fishing losses in the Snake and Columbia rivers.

As a low SAR (LSAR), we used the average SAR of 0.012 for the early 1990s (1990–1994) from Petrosky et al. (2001). As a high SAR (HSAR), we used their average SAR of 0.039 for the years before the Lower Granite Dam was constructed (1962–1974). We assumed that SARs for summer steelhead and sockeye would have equivalent ranges. That assumption seems justified, at least for steelhead, by the similar SARs of spring/summer chinook and steelhead in the early 1960s (see Raymond 1979).

The SARs for fall chinook were estimated from coded-wire tag recoveries of summer/fall chinook released in the mid-Columbia River region. For yearling fish released at Rocky Reach Hatchery, just upstream of Rock Island Dam, total survival averaged 0.0149 over brood years 1982–1989. Survival of subyearlings would be lower. When SARs were plotted for subyearling fall chinook transported from McNary Dam to the tailrace of Bonneville Dam (Figure 51 in Chapman et al. 1994), survival rates ranged from near zero in 1988 to 0.014. Most values ranged from 0.003 to 0.006. Inspection of the data suggested to us that an SAR of 0.004 would be a

Page 6 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives reasonable estimate of an LSAR. Survival rates of subyearling fall chinook from Priest Rapids Hatchery averaged 0.004 in brood years 1986–1989 and 0.025 in the longer period 1979–1989 (Appendix E-6 in Chapman et al. 1994). We chose 0.018 to represent an HSAR.

Chapman et al. (1990) estimated the SAR of Redfish Lake sockeye as 0.0009 to 0.032 (mean 0.0138 for smolt years 1955–1964), based on data in Bjornn et al. (1968). The SAR from Lower Granite Dam to the Columbia River mouth would be higher. The SAR of hatchery-reared sockeye released to Lake Wenatchee was estimated as 0.004 to about 0.02 (Table 3 in Chapman et al. 1995).

2.3. Estimates of Required Escapement

We calculated the escapement of adults at Lower Granite Dam necessary to replace the estimated smolt production from each of the subbasins above Hells Canyon Dam (Table 21 in Chapman and Chandler 2001b). We estimated a range of required escapement based on two sets of assumptions involving prespawn mortality, fecundities, and egg-to-smolt survival and adult interdam loss. We assumed two levels of interdam loss of adults that passed upstream using the river corridor, as opposed to a scenario involving the transport of adults from Hells Canyon Dam. The two sets of assumptions that we used to estimate required escapement are referred to as low required escapement (LRE) and high required escapement (HRE). The LRE would require less escapement at Lower Granite Dam to replace smolt production than would the HRE. For both sets of assumptions, we assumed no fishing-related mortality in the Snake River.

We applied both sets of assumptions to each of the two SARs described earlier, producing four estimates of required escapement for each reintroduction scenario: 1) LSAR and HRE; 2) LSAR and LRE; 3) HSAR and HRE; and 4) HSAR and LRE. The extremes of the range of escapement estimates will be numbers 1 (greatest adults required, worst case) to 4 (least adults required, best case).

2.3.1. Low Required Escapement (LRE)

We assumed an average fecundity of 4,500 for spring chinook (mean of Grande Ronde and Imnaha fecundities as reported by the Oregon Department of Fish and Wildlife (ODFW 1987), 5,000 for steelhead (ODFW 1987), and 4,300 for fall chinook (Haas 1965).3 We used an assumed survival rate from potential eggs to smolts of 0.05 for spring chinook (within range of survivals in ODFW 1987), 0.02 for steelhead (also within range of survivals in ODFW 1987 and comporting with Thurow’s [1987] estimate of egg-to-smolt survival in good habitat), and 0.15 for fall chinook. Mullan et al. (1992) estimated egg-to-smolt survival rates of 0.048 to 0.152 for summer/fall chinook in the Wenatchee and Methow rivers, and McIsaac (1990) found survival rates of 0.04, 0.13, and 0.09 for the brood years 1977, 1978, and 1979, respectively, for fall chinook in the Lewis River. Assumed prespawning losses that occur after adults pass Lower Granite Dam differed by species: 0.20 for spring chinook, 0.10 for steelhead, and 0.30 for fall chinook. We assumed adult interdam losses (between the head of Brownlee Reservoir and

3 Mean fecundity equaled 4,259 eggs per female in hatchery operations at Oxbow Dam, 1961–1963.

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Lower Salmon Falls Dam) of 0.04 per project for all species. This loss rate is frequently used in discussions of mainstem passage efficiencies (Pratt and Chapman 1989, Chapman et al. 1991, Chapman et al. 1994). For simplicity, we used a 1:1 sex ratio for all species. We provide no assumptions for sockeye because we did not estimate escapement requirements for this species.

2.3.2. High Required Escapement (HRE)

For a less-optimistic escapement requirement, we assumed fecundities of 4,000 for spring chinook, 4,500 for steelhead, and 4,300 for fall chinook. The fecundity for spring chinook is based on the ODFW (1987) assumption for most Columbia basin streams except the Grande Ronde and Imnaha rivers. The fecundity for steelhead is based on that assumed for the Imnaha River (ODFW 1987). Finally, the fecundity for fall chinook is based on data from Haas (1965). We used prespawning loss rates of 0.30 for spring chinook, 0.15 for steelhead, and 0.40 for fall chinook. Egg-to-smolt survival rates were 0.03 for spring chinook, 0.01 for steelhead, and 0.06 for fall chinook (Petrosky 1990). As with the LRE, the rates for spring chinook and steelhead fall within the survival ranges offered by the ODFW (1987). We assumed an adult interdam loss rate of 0.05 per project for dams upstream of Hells Canyon Dam. As with the LRE, we used a 1:1 sex ratio for all species.

2.4. Reintroduction Scenario Evaluations

Each of the reintroduction scenarios evaluated (Table 2) estimates a range of adult returns to the subbasin based on assumptions of low and high SARs and low and high required escapement. Smolt yield estimates from Table 21 in Chapter 8 (Chapman and Chandler 2001b) were the basis of the number of smolts leaving a potential subbasin (assumed production under full seeding). We did not account directly for factors influencing smolt yield in each of the subbasins other than mechanisms that are indirectly represented in the egg-to-smolt survival estimates and prespawn mortality estimates presented for the escapement requirement. Therefore, factors that could reduce subbasin smolt output—such as reservoir passage or collection within the basin, losses in irrigation diversions, or predation during the outmigration—are not accounted for in these scenarios.

2.4.1. Scenario 1: Free-Flowing River Passage

The free-flowing river scenario assumes that smolts can pass downstream of an individual subbasin to the upstream end of Lower Granite Reservoir under the survival conditions they would find in a free-flowing river. Although this is not a realistic scenario, we use it as a comparison with other scenarios that involve some level of reservoir passage or transportation. The free-flowing scenario also allows us to evaluate the effects of distance from the Lower Granite tailrace relative to smolt survival. The production potential considered in this scenario is only for the portions of the subbasins that would be accessible under a free-flowing Snake River scenario. This production potential is equivalent to the smolt production estimates of Option A (described in Chapter 8, Chapman and Chandler 2001b) that consider smolt production under the assumption of mainstem passage at all Idaho Power Company (IPC) dams. The free-flowing assumption is for downstream passage only. Therefore, mainstem production

Page 8 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives areas exclude mainstem reservoirs. From Table 21 in Chapter 8 (Chapman and Chandler 2001b), this production potential equates to 699,673 spring chinook smolts, 317,637 steelhead smolts, and 4,274,161 fall chinook smolts.

2.4.2. Scenario 2: Passage at Hells Canyon Dam and Oxbow Dam

This scenario allows for upstream passage of adults at Hells Canyon and Oxbow dams. Basins available for production include Pine Creek and the Wildhorse River for spring chinook salmon and steelhead. In addition, Indian Creek would be available for steelhead production. The scenario includes bypass facilities at both Oxbow and Hells Canyon dams, with the assumption that survival rates for downstream migrants would be similar to those observed for Lower Granite Dam as described earlier in this chapter. This scenario does not include any potential production for fall chinook salmon. Some production could possibly be achieved using the Oxbow Bypass (the bypassed reach between Oxbow Dam and the powerhouse). However, for reasons discussed in Myers and Chandler (2001), we did not include the bypass in this scenario.

2.4.3. Scenarios 3A and 3B: Passage of Adults at Brownlee Dam— 1957 Subbasin Availability

Scenarios 3A and 3B assume that the availability and use of basins upstream of Brownlee Dam are the same as in 1957, immediately before construction of this dam (see Chapter 4, Chandler and Chapman 2001). Subbasins open for spring chinook and steelhead production include Eagle Creek in the Powder River basin and the Weiser River (Raleigh and Ebel 1968). In addition, several smaller tributaries along Brownlee Reservoir and in the Powder River basin would presumably produce a small number of steelhead. Fall chinook salmon production areas also would be opened downstream of Swan Falls Dam. As discussed in Chapters 7 (Chapman and Chandler 2001a) and 8 (Chapman and Chandler 2001b), we assumed that these areas would produce levels comparable to the time of closure by the dam, despite the questions of habitat quality raised in Chapter 5 (Chandler and Groves 2001). For modeling purposes, we assumed that all fall chinook would be required to travel from Walters Ferry. The majority of production immediately before the time of closure was from Swan Falls Dam to Marsing. Walters Ferry lies approximately in the middle of this reach.

Scenarios 3A and 3B assume that either would be implemented in combination with Scenario 2 and that adults would be trapped or laddered at Brownlee Dam for spring chinook and steelhead to return volitionally to the subbasins downstream of Brownlee Dam. If either scenario were not implemented in combination with Scenario 2, adults could be transported from Hells Canyon Dam to a point upstream of Brownlee Dam. Scenarios 3A and 3B do not include any downstream passage bypass or collection associated with Brownlee reservoir or dam, and they assume bypass facilities at both Oxbow and Hells Canyon dams, as in Scenario 2. This passage situation through Brownlee Reservoir is comparable to the conditions prevalent in 1963 and 1964 when most downstream fish passed through turbines or spill. As such, Scenario 3A includes passage through Brownlee Reservoir with a maximum reservoir drawdown of 89 ft as in 1964. Scenario 3B includes passage through Brownlee Reservoir with a maximum reservoir drawdown of 21 ft as in 1963.

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2.4.4. Scenario 4: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Upper Reservoir Collection

This scenario is the same as Scenarios 3A and 3B, with the addition of a collection facility in upper Brownlee Reservoir as described in Chapter 9 (Aurdahl et al. 2001). This facility would involve two portable floating traps. As discussed in Chapter 9 (Aurdahl et al. 2001), the collection efficiency of this type of system is questionable. For the purposes of this scenario, we assumed a collection efficiency of 50%. Fish produced upstream of Brownlee Reservoir would be collected and transported to the tailrace of Hells Canyon Dam. Transport survival is assumed to be high at 0.98. Juveniles that are not collected, along with production from the Powder River (Eagle Creek) and small tributaries of Brownlee Reservoir, would pass through a full Brownlee Reservoir at survival rates as observed in the 1963 survival study (Raleigh and Ebel 1968). The maximum reservoir drawdown would be 21 ft, and there would be no bypass facility at Brownlee Dam. However, bypass facilities would be present at Oxbow and Hells Canyon dams as described earlier.

2.4.5. Scenarios 5A and 5B: Passage of Adults at Brownlee Dam— 1957 Subbasin Availability, Collection and Transport at Brownlee Dam

This pair of scenarios is comparable to Scenarios 3A and 3B, with the addition of a collection facility at Brownlee Dam that would transport fish to the tailrace of Hells Canyon Dam. Transport survival is assumed to be high at 0.98. Scenarios 5A and 5B assume that the facility at Brownlee Dam would have an 80% collection efficiency and that the facility would be functional at any reservoir level. Scenario 5A assumes an 89-ft maximum drawdown of Brownlee Reservoir (1964 conditions), and Scenario 5B assumes a 21-ft maximum drawdown (1963).

2.4.6. Scenarios 6A and 6B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam

Scenarios 6A and 6B (as well as 7A, 7B, 8A, 8B, 9A, and 9B) involve upstream passage facilities for adults from Hells Canyon Dam to C.J. Strike Dam. If Scenario 6A or 6B were not implemented in combination with Scenarios 2 through 5, then adults could be transported to the area upstream of Swan Falls Dam. Areas that would be opened for potential production include the mainstem Snake River between Swan Falls Reservoir and C.J. Strike Dam and the mainstem between C.J. Strike Reservoir and Bliss Dam. In addition, the Bruneau River basin would be accessible for spring chinook and steelhead. For juvenile passage, a bypass facility would be in place at C.J. Strike Dam, with survival rates comparable to Lower Granite Dam. Scenarios 6A and 6B further assume that a collection facility at Swan Falls Dam would be in place to collect and transport juveniles to a point downstream of Hells Canyon Dam. We assumed an 80% collection efficiency for this facility, and a high survival of 0.98. Scenario 6A assumes that fish not collected and transported at Swan Falls Dam would pass through an 89-ft drawdown in Brownlee Reservoir without a bypass facility Brownlee Dam. Scenario 6B assumes that nontransported fish would pass through a 21-ft drawdown in Brownlee Reservoir without a bypass facility at Brownlee Dam. Scenarios 6A and 6B further assume collection and bypass facilities at Oxbow and Hells Canyon dams as in Scenario 2.

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2.4.7. Scenarios 7A and 7B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam, Collection and Transport at Brownlee Dam

Scenarios 7A and 7B are a combination of Scenarios 5 and 6. Scenarios 7A and 7B involve a bypass facility at C.J. Strike Dam and collection and transport facilities at Swan Falls and Brownlee dams. Both facilities would have an 80% collection efficiency and a 98% transport survival rate. Fish collected at Swan Falls and Brownlee dams would be transported to the tailrace of Hells Canyon Dam. Scenario 7A assumes an 89-ft maximum drawdown in Brownlee Reservoir; Scenario 7B assumes a 21-ft maximum drawdown. Both Scenarios 7A and 7B include bypass facilities at Oxbow and Hells Canyon dams.

2.4.8. Scenario 8A and 8B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, 100% Bypass at Brownlee Dam

Scenarios 8A and 8B assume bypass at all projects, with similar reservoir survival rates as those observed at Lower Granite Dam. We assumed that the bypass facility at Brownlee Dam would be 100% effective (i.e., no turbine or spill mortality). As in the other scenarios, Scenario 8A involves an 89-ft maximum drawdown of Brownlee Reservoir, and Scenario 8B involves a 21-ft maximum drawdown.

2.4.9. Scenarios 9A and 9B: Collection at C.J. Strike Dam, 100% Bypass at Brownlee Dam

Scenarios 9A and 9B assume that collection at C.J. Strike Dam would occur at an 80% efficiency and that bypass at all other facilities would occur as in Scenarios 8A and 8B. This scenario involves only the Bruneau River basin and potential production of fall chinook in the mainstem Snake River upstream of C.J. Strike Dam.

3. RESULTS

Table 3 presents mortality coefficients and survival estimates by species for individual reaches of the Snake River. The two estimates of survival through Brownlee Reservoir are based on maximum drawdowns of 21 ft and 89 ft, the conditions used to estimate survival in 1963 and 1964, respectively.

Tables 4 through 6 present estimates of required escapement for each of the subbasins and species to replace the smolt production that we estimated in Table 21 in Chapter 8 (Chapman and Chandler 2001b). We present both sets of required escapement assumptions (low and high) for both transported adults and nontransported adults (i.e., in-river passage to subbasins). As expected, based on the assumptions of interdam losses, transport options required fewer adults at Hells Canyon Dam than did the in-river passage option. The benefit increased as distance from Hells Canyon Dam increased. For example, if adults were transported, approximately 4 to 5%

Hells Canyon Complex Page 11 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company fewer adults would be required at Hells Canyon Dam for the Wildhorse River to meet subbasin potential, whereas 15 to 18% fewer adults would be required for the Bruneau River. However, under transportation options from Hells Canyon Dam, individual adults would have to be sorted into the correct basins. This implies some basin-specific mark by which returning adults could be identified. This requirement introduces another set of challenges and feasibility questions. Further discussion of required escapement under the different scenarios is based on the assumption of in-river passage.

3.1. Free-Flowing River Scenario

As expected, in the free-flowing river scenario, smolt survival from subbasins decreased as the distance from Lower Granite Reservoir increased. The Pine Creek basin had survival rates of 0.79 for spring summer chinook and 0.83 for steelhead (Figure 1). Survival rates from Rock Creek, the farthest upstream basin, ranged from 0.54 for spring chinook to 0.64 for steelhead. Fall chinook survival rates ranged from 0.33 at Walters Ferry to 0.25 upstream of C.J. Strike Dam.

The proportions of estimated adult returns at Hells Canyon Dam to estimates of required escapement to meet the subbasin production potential decreased as the distance from Hells Canyon Dam increased (Figure 2). For spring chinook salmon under the best case of assumptions (HSAR and LRE), escapement was nearly double what would be required at Pine Creek. For Rock Creek, the subbasin furthest upstream, escapement at Hells Canyon Dam was about equal to what would be required. Under the less optimistic sets of assumptions (LSAR), the escapement at Hells Canyon Dam would be much less than the required escapement. For steelhead and fall chinook salmon, under all sets of assumptions, escapement at Hells Canyon was less than what would be required to meet the production area potential (Figure 2). At some of the lower basins (Pine Creek to the Powder River), steelhead were within 10% of the level required under the best set of assumptions. Fall chinook, under a free-flowing river scenario, were within 15% of meeting required escapement levels under the best set of assumptions. However, under the other sets of assumptions, the proportion of escapement to required escapement was less than 0.5 (Figure 2).

3.2. Oxbow and Hells Canyon Scenarios

3.2.1. Scenario 2: Passage at Hells Canyon Dam and Oxbow Dam

This scenario allows upstream passage of adults at Hells Canyon and Oxbow dams, opening the Wildhorse River and Pine and Indian creeks. The scenario includes bypass facilities at both Oxbow and Hells Canyon dams and assumes a downstream migrant survival rate similar to that observed at Lower Granite Dam.

For spring chinook, smolt survival from Pine Creek to the Lower Granite tailrace was estimated at 0.77; from the Wildhorse River to the Lower Granite tailrace, 0.74 (Table 7). Because this scenario involves only Hells Canyon Reservoir, survival estimates are relatively close to the

Page 12 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives estimates for the free-flowing river scenario. Table 8 presents the number of smolts arriving at Lower Granite Reservoir. Adult returns of spring chinook to Hells Canyon Dam ranged from 373 to 1,212 under the LSAR and HSAR assumptions, respectively (Table 9). Adult returns to the Wildhorse River were estimated to be 233 to 756 under the two SAR assumptions. Under the HSAR and LRE assumptions, adult returns of spring chinook to Pine Creek well exceeded the level required to maintain subbasin smolt production (Figure 3). However, the LSAR estimates were well below what would be required under both the LRE and HRE assumptions, suggesting that smolt production levels could not be maintained. The Wildhorse River had a similar pattern (Figure 4).

Steelhead smolt survival was also comparable to that of the free-flowing river scenario, and it was slightly higher than for spring chinook (Table 10). Table 11 presents an estimate of the number of smolts arriving at Lower Granite tailrace. Adult returns to Hells Canyon Dam under this scenario and under the two SAR assumptions were estimated at 159 to 518 for Pine Creek. Indian Creek was estimated at 21 to 70, and the Wildhorse River at 93 to 302 (Table 12). Only under the HSAR and LRE assumptions was escapement at Hells Canyon Dam adequate to meet subbasin potential at Pine Creek and the Wildhorse River (Figures 3 and 4). Under the LSAR assumptions, escapement was well below the level needed.

3.3. Upstream of Brownlee Dam Scenarios

3.3.1. Scenarios 3A and 3B: Passage of Adults at Brownlee Dam— 1957 Subbasin Availability

Scenarios 3A and 3B allow adults to return to basins and mainstem production areas available upstream of Brownlee Dam. These scenarios assume that only those areas producing anadromous fish before Brownlee Dam construction would be capable of some production. Scenario 3A assumes an 89-ft maximum drawdown in Brownlee Reservoir, and Scenario 3B assumes a 21-ft maximum drawdown. Brownlee Reservoir passage would be equivalent to 1963 and 1964 (i.e., no functioning bypass system). These scenarios assume bypass systems in place at Oxbow and Hells Canyon dams.

Under Scenario 3A (89-ft drawdown), spring chinook produced in the Eagle Creek basin (Powder River) survived at just over half the survival level of the free-flowing river scenario. Under Scenario 3B (21-ft drawdown), survival was less than half that of the free-flowing river scenario (Table 7). In the Weiser River, the only other basin producing spring chinook, survival levels were much less, ranging from 0.26 for the 89-ft drawdown to only 0.09 for the 21-ft drawdown (Table 7). Table 8 presents the numbers of smolts arriving at Lower Granite tailrace under these scenarios. Weiser River fish have to travel the entire distance of Brownlee Reservoir. Steelhead smolts from the two basins had similar survival estimates (Table 10). Table 11 presents the numbers of steelhead arriving at the Lower Granite tailrace.

Fall chinook smolts produced below Swan Falls Dam had very low survival estimates under these scenarios. The rates ranged from 0.10 for the 89-ft drawdown to 0.03 for the 21-ft

Hells Canyon Complex Page 13 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company drawdown (Table 13). Table 14 presents the numbers of smolts arriving at Lower Granite tailrace.

Adults returns of spring chinook for the Powder River were not very different for the two drawdown conditions (Table 9). However, as expected based on smolt survivals, the Weiser River returns were much lower under the 21-ft drawdown condition (Table 9). Powder River adult returns were better. Under the 89-ft drawdown and the HSAR with LRE assumptions, required adult escapement met the level needed to maintain basin production (Figure 5). The LSAR assumptions were well below the level required. Regardless of which drawdown and which set of assumptions were used, adult returns to Hells Canyon Dam and destined for the Weiser River were well below the level required under any of the sets of assumptions (Figure 6). Steelhead adult returns to Hells Canyon Dam (Table 12) were also well below the required level of escapement for both the Powder and Weiser rivers (Figures 5 and 6).

Fall chinook adult returns ranged from 494 to 2,219 under the two SAR conditions and the 89-ft drawdown of Brownlee Reservoir. Under the 21-ft drawdown, adult returns ranged from 162 to 732, depending on the SAR (Table 15). These adult returns were well under the level required for escapement, regardless of the sets of assumptions (Figure 7A).

3.3.2. Scenario 4: Passage of Adults at Brownlee Dam—1957 Subbasin Availability, Upper Reservoir Collection

Scenario 4 includes an upper reservoir collection facility in Brownlee Reservoir near the Burnt River confluence. The assumed collection efficiency of this facility is 50%. The reservoir condition was a maximum drawdown of 21 ft. For fish from the Powder River basin, this scenario is equivalent to Scenario 3B. Collection at the upstream end of Brownlee Reservoir made some differences to survival and adult returns relative to Scenario 3B for smolts from production areas upstream of Brownlee Dam. In general, smolt survival and adult returns were slightly better under scenario 4, but were comparable to Scenario 3A, which includes an 89-ft drawdown of Brownlee Reservoir (Figures 6 and 7A, Tables 7–14).

3.3.3. Scenarios 5A and 5B: Passage of Adults at Brownlee Dam— 1957 Subbasin Availability, Collection and Transport at Brownlee Dam

Scenarios 5A and 5B are comparable to Scenarios 3A and 3B, with the addition of a collection facility at Brownlee Dam that would transport fish to the tailrace of Hells Canyon Dam. Scenarios 5A and 5B assume that the collection facility would have a collection efficiency of 80%.

Of all the scenarios, scenario 5A had the best overall results for smolt survival and adult returns. Smolts from the Powder River showed the greatest benefit from collection at Brownlee Dam; their survival rate increased approximately 20% over that of Powder River smolts under Scenario 3A. However, smolt survival for the Weiser River improved by approximately 10% for spring chinook (Table 7) and 12% for steelhead (Table 10) when compared with the respective smolts under Scenario 3A. The survival rate for fall chinook smolts increased only 4% over that of Scenario 3A (Table 13). Passage through the reservoir, even at a low drawdown, renders

Page 14 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives collection at Brownlee Dam to be of little benefit. Scenario 5B, with a 21-ft maximum drawdown in Brownlee Reservoir, did not differ greatly from Scenario 3B.

Spring chinook adult returns to the Powder River under both Scenarios 5A and 5B exceeded the level required to maintain basin smolt production under the HSAR and LRE assumptions (Figure 5). The LSARs were well below either required escapement level, as were adult returns to the Weiser River under any set of assumptions. Both steelhead and fall chinook adult returns were well below the required escapement levels (Figures 5–7A).

3.4. Upstream of Swan Falls Dam Scenarios

3.4.1. Scenarios 6A and 6B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam

Scenarios 6A and 6B expand adult passage to production areas between Swan Falls and Bliss dams. These scenarios assume bypass facilities at C.J. Strike Dam and that collection facilities at Swan Falls Dam have 80% efficiency. Scenario 6A passes uncollected fish through an 89-ft maximum drawdown at Brownlee Reservoir without bypass facilities. Scenario 6B passes fish through a 21-ft maximum drawdown.

Spring chinook smolt survival rates from the Bruneau River basin ranged from 62 (Scenario 6B) to 65% (Scenario 6A), demonstrating a 3% survival benefit in drafting Brownlee Reservoir (Table 7). Table 8 presents the numbers of smolts arriving at the Lower Granite tailrace. Adult returns ranged from 2,022 to 6,570 under the 89-ft drawdown of Brownlee Reservoir. Adult returns under both scenarios 6A and 6B were slightly better than adult returns under the free- flowing river scenario (Table 9). Adult returns for spring chinook under the best set of assumptions (HSAR and LRE) exceeded the level required to maintain smolt production. However, steelhead returns were still below the level required (Figure 8).

Fall chinook are produced upstream of both Swan Falls and C.J. Strike reservoirs. As would be expected, the survival rate of smolts above the C.J. Strike Project is less than it is for those originating from below that project. However, under Scenarios 6A and 6B, the survival rate of fall chinook in both reaches was higher than any level achieved for the Walters Ferry Reach, except under the free-flowing river scenario (Table 13). Survival exceeds the free-flowing river scenario under both reaches. Adult returns for smolts from areas downstream of the C.J. Strike Dam slightly exceeded the level required to maintain smolt production for the reach under the HSAR and LRE assumptions (Figure 7B). However, fall chinook returns above C.J. Strike Dam fell just short of levels required to maintain production (Figure 7C).

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3.4.2. Scenarios 7A and 7B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, Collection at Swan Falls Dam, Collection/Transport at Brownlee Dam

Scenarios 7A and 7B differ from Scenarios 6A and 6B regarding passage at Brownlee Reservoir. Scenarios 7A and 7B assume a collection facility at Brownlee Dam that would collect and transport 80% of the fish that were not collected at the facility at Swan Falls Dam.

As in Scenarios 6A and 6B, only slight improvements were observed with collection at Brownlee Dam of fish that were not collected at Swan Falls Dam. As such, adult returns were basically the same under scenarios 7A and 7B as they were under Scenarios 6A and 6B. Adult escapement at Hells Canyon Dam exceeded levels required to maintain smolt production for spring chinook and fall chinook under the best set of assumptions (Figures 7 and 8). Also, as with Scenarios 6A and 6B, overall survival to Lower Granite Dam was slightly better than under the free-flowing river scenario.

3.4.3. Scenarios 8A and 8B: Passage of Adults from Hells Canyon Dam to C.J. Strike Dam, 100% Bypass at Brownlee Dam

Scenarios 8A and 8B do not include collection and transport, but rather bypass facilities with efficiency comparable to Lower Granite Dam. For Brownlee Reservoir, a 100% bypass efficiency is assumed for passage around Brownlee Dam. Under our set of earlier assumptions, this efficiency rate means that 100% of the fish were passed through spill. This scenario includes both an 89-ft drawdown (Scenario 8A) and a 21-ft drawdown (Scenario 8B).

Substantial decreases in smolt survival occurred with these scenarios compared with the free- flowing river scenario and the collection/transport options of Scenarios 6A, 6B, 7A, and 7B. For spring chinook and steelhead, the survival rate decreased by over 50% for the 89-ft drawdown option (Scenario 8A), and by 85% for the 21-ft drawdown option (scenario 8B) (Tables 7 and 10). Adult returns fell well below the levels needed to maintain production, even under the 89-ft drawdown scenario of Brownlee Reservoir (Figures 7 and 8).

3.4.4. Scenarios 9A and 9B: Collection at C.J. Strike Dam, 100% Bypass at Brownlee Dam

This scenario includes collection of fish above C.J. Strike Dam with an 80% collection efficiency and a 98% transport survival rate. Overall, results for these scenarios did not differ appreciably from those of Scenarios 7A, 7B, 8A, and 8B. The level of Brownlee Reservoir drawdown resulted in about a 4% difference in smolt survival for spring chinook and steelhead, and about a 1% difference for fall chinook (Tables 7, 10, and 13). Adult returns were slightly better than those in Scenarios 6 and 7, suggesting a slight benefit from collection at C.J. Strike Dam as opposed to Swan Falls Dam (Figures 7 and 8). Only Bruneau River spring chinook exceeded the level required to maintain smolt production under the HSAR and LRE assumptions (Figure 8). Fall chinook and steelhead both fell short of replacement under any set of assumptions (Figures 7 and 8).

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4. DISCUSSION

4.1. Ability to Maintain Production Potential

None of the potential reintroduction scenarios we analyzed allowed any of the species in any of the production areas to return at sufficient levels to maintain production potential using the LSAR estimates under either set of required escapement assumptions. Even under assumptions of a free-flowing river for smolt passage to the head of Lower Granite Dam, returns were not high enough using the LSAR estimates. LSAR assumptions are representative of conditions prevalent in the early 1990s (Petrosky et al. 2001).

Under the HSAR assumptions, representing average conditions prevalent in the 1960s before Lower Granite Dam construction (Petrosky et al. 2001), spring chinook salmon returned at levels that would meet or exceed the LRE set of assumptions in Pine and Eagle creeks and the Wildhorse and Bruneau rivers (under transport assumptions) under one or more of our scenarios. However, none of the basins exceeded the HRE assumptions. Steelhead returns just met required escapement levels in Pine Creek only under the LRE assumptions and only under the survival estimates for the free-flowing river scenario. Return levels were within 10% of the LRE under Scenario 2 for the Wildhorse River and Pine and Indian creeks. Fall chinook did not return at high enough levels to the Walters Ferry Reach under any of the sets of assumptions, and they only approached the level required under the LRE assumptions under the free-flowing river scenario. However, under the collection and transport options at Swan Falls and C.J. Strike dams, fall chinook survival exceeded that under free-flowing conditions. Under the HSAR estimates, they met or exceeded levels required under the LRE set of assumptions.

It is important to note that a failure to meet required escapement levels for maintaining production potential does not necessarily imply that a population could or could not persist. Ultimately, the shape of the stock-recruitment function for each of the production areas would determine the ability of a population to persist. For example, if the function lies entirely below the replacement line in the model that describes parent and progeny abundance in wild or natural spawning areas, the population would become extinct. If the function lies above the replacement line at spawner abundance that is a fraction of seeding required for maximum surplus production, biological compensation may permit the population to sustain itself at some reduced level. However, we do know that under conditions prevalent at the time Brownlee Reservoir was constructed, the number of anadromous fish declined quickly under the passage conditions available in Brownlee Reservoir. We also know that many wild/natural Snake River stocks of salmon and steelhead in the areas below Hells Canyon Dam have declined to levels that led to protection under the Endangered Species Act.

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4.2. Assumptions

4.2.1. Survival Estimates

Our mortality coefficient for passage through C.J. Strike, Swan Falls, Oxbow, and Hells Canyon reservoirs was based on project mortality in Lower Granite Reservoir. We consider this coefficient to be an underestimate of loss per kilometer in the Oxbow and Hells Canyon projects. Hells Canyon Dam has over twice as much head (210 ft) as Lower Granite Dam (98 ft). Oxbow Dam has 120 ft of head. If a higher mortality coefficient were used, as we think would be appropriate, smolt arrivals at the Lower Granite tailrace would be reduced for all scenarios except Scenario 1. This reduction holds true even for smolt transportation options because under our assumptions of an 80% collection efficiency, 20% of smolts that arrive at collector dams would have to migrate through Oxbow and Hells Canyon reservoirs.

Our estimates of survival through various free-flowing and reservoir reaches show that smolts originating farther up the Snake River have lower survival rates to the Lower Granite tailrace than do fish from subbasins lower in the river. When the National Marine Fisheries Service PIT- tagged presmolts in Idaho and Oregon tributaries in several years, Achord et al. (1995a, 1995b, 1996) found a rather consistent pattern of lower survival rates for presmolts PIT-tagged in the Salmon River basin at higher elevation and longer distances from interrogation points at dams.

For survival estimates for free-flowing river, we assumed that survival rates per kilometer estimated for the Salmon River for spring chinook and steelhead would be comparable to rates for free-flowing sections of the Snake River upstream of the Hells Canyon Complex (HCC). Similarly, we assumed that fall chinook survival rates in the free-flowing Snake River downstream of Hells Canyon Dam would be comparable to those for free-flowing sections upstream of the HCC. We found no information that would permit us to estimate relative survival rates of smolts that migrate in the Salmon and Snake rivers. However, we believe that, for several reasons, these assumptions offer conservative estimates of survival for free-flowing sections upstream of Hells Canyon Dam. During the spring months, water temperature warms at a faster rate in the Snake River upstream of the HCC than it does in the Snake River downstream of the HCC or in the Salmon River. These water temperature differences may result in higher predation losses from warmwater fish species becoming active earlier upstream of the HCC during the smolt outmigration. In addition, the free-flowing river upstream of Hells Canyon supports a much more diverse community of warmwater predators than the Salmon River or even the Snake River downstream of the HCC. Warmwater fish species in the Snake River upstream of Brownlee Reservoir include a large population of channel catfish, flathead catfish, largemouth bass, and smallmouth bass, as well as native predators such as the northern pikeminnow.

4.2.2. Smolt-to-Adult Returns and Required Escapement Assumptions

Our approach to estimating escapement levels required to maintain basin production potential can be compared with information presented by Petrosky et al. (2001) for spring chinook. Petrosky et al. (2001) estimated smolts per spawner (smolts/spawner) for wild spring/summer

Page 18 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives chinook using adult escapement and subsequent smolt arrivals at the same point. Their estimates ranged from 41 to 182 smolts per spawner (Table 2 in Petrosky et al. 2001). This statistic integrates information for spring/summer chinook from many subbasins that are subject to heavy commodity production (e.g., logging, grazing, irrigating, mining) and many subbasins that have relatively good habitat conditions. Therefore, we can use Petrosky et al. (2001) results for comparison only with the return of adults to Hells Canyon Dam. We used their average smolts- per-spawner statistic for the years before Lower Granite Project construction (71 smolts/spawner for 1962–1974) to assess required escapement appropriate for our HSAR estimate of 0.039, also from Petrosky et al. (2001). We used their mean for the early 1990s (93 smolts per spawner for 1990–1994) as appropriate for our LSAR of 0.012. The increasing trend in smolts per spawner in the Petrosky et al. (2001) time series coincides with a decreasing trend in spawner numbers and is indicative of density dependence in the early life stages.

We estimated adult returns to Hells Canyon Dam from Pine Creek at 386 under the LSAR estimate and 1,252 under the HSAR. If we adjust those returns to Lower Granite Dam (multiply the Hells Canyon Dam estimate by 1.04), adult returns become 401 (LSAR) and 1,302 (HSAR). Using the early 71 smolts-per-spawner statistic (corresponding to the HSAR), the number of smolts produced by those adults would be 92,442, or 158% of the basin potential. Using the later 93 smolts-per-spawner statistic for the LSAR estimate produces 37,296 smolts, or 64% of the basin potential. With the LSAR estimate, 629 adults would be required to meet production potential. Under the HSAR, 824 adults would be required to meet basin potential. Our estimates of required escapement were 650 adults under the LRE assumptions and 1,392 under the HRE assumptions. Using the smolts-per-spawner approach, adult returns under the LSAR estimate at Lower Granite Dam for Rock Creek, the uppermost basin, would produce approximately 43% of the basin production potential. Adult returns under the HSAR estimate would produce 108% of the basin production potential, comparable to our method. Figure 9 shows the proportion of adult returns to the required escapement to Lower Granite Dam using the two approaches and our free- flowing river scenario. With this comparison, it seems reasonable to use our LRE estimates to compare with our adult returns for LSAR estimates and our HRE estimates to compare with adult returns for our HSAR estimates. Regardless of the method used, the SAR of the early 1990s is clearly insufficient to return enough adults to replace subbasin production potential even in the free-flowing river scenario. The HSAR, at least for spring chinook, is enough to replace subbasin output even as far upstream as Rock Creek under a free-flowing river scenario and a no-fishing assumption. Similar comparisons for steelhead or fall chinook were not available.

We see considerable room for variation in our required escapement estimates resulting from different assumptions of egg-to-smolt survival, prespawning survival, and fecundity, particularly to assumptions for fall chinook. We used fecundities of 4,300 eggs per female. Lyons Ferry Hatchery uses 3,300 eggs per female to estimate their green egg take. We used the 0.06 egg-to- smolt estimate of Petrosky (1990) for our estimates for HRE. Even our LRE estimate of 0.15 egg-to-smolt survival, coupled with what we believe would be a relatively high prespawning survival rate, did not produce model results that indicated a self-sustaining, fully seeded population in the Walters Ferry Reach of the Snake River in the free-flow scenario with HSAR (Figure 7). We would have to assume sharp increases either in smolt survival to Lower Granite Dam or in SAR, or we would have to reduce considerably the estimated escapement requirement, before the modeling results would show that we could achieve fall chinook returns sufficient to support full seeding even without fishing in the Columbia River.

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Petrosky (1990) estimated that an SAR of 0.01 would suffice to permit fall chinook in the Walters Ferry area to sustain. However, his SAR embodies spawning adults in the Walters Ferry Reach, not SAR from Lower Granite Dam. Thus, his SAR should be considered as applicable only after accounting for fishing harvests, interdam losses, and prespawning mortality. Prespawning mortality assumptions strongly influence escapement requirements. For example, our estimates for prespawning survival for fall chinook were 0.60 and 0.70 for the high and low escapement requirements, respectively. If we were to increase prespawning survival to 0.85 for the low escapement alternative, the required escapement would decrease by almost 18%.

Chapman et al. (1994) used data from Meekin et al. (1966) and Meekin (1967) to calculate a prespawning loss of about 0.37 for summer/fall chinook entering the Methow River, an upper Columbia River subbasin. They based their estimate on a known escapement of 1,716 adults and a redd count of 543 in 1965. These data convert to 3.16 fish per redd.4 We assumed that two adults would be required for each redd. Survival can thus be calculated as (543 × 2) ÷ 1,716. In 1966, 3,703 adults passed the electric fence and produced 1,192 redds, a ratio of 3.1 fish per redd. This rate would lead to a prespawning loss estimate of 0.37. Chapman et al. (1994) stated:

We believe, on the foundation of Meekin et al. (1966) and Meekin (1967) that it is reasonable to estimate summer/fall chinook pre-spawning mortality as between 30% and 40%. That figure would apply to escapement counted at the last dam downstream of spawning areas or estimated by subtraction of counts at sequential dams. It may be too low for the Okanogan and Similkameen escapement in light of the required length of migration of adults through the Okanogan River.

Similar estimates of fall chinook prespawning mortality were made for the Snake River using redd counts and estimated adult escapement at Lower Granite Dam during the years 1993–2000 (IPC, unpubl. data). During those years, weekly redd count flights were conducted on the Snake River and tributaries (Clearwater, Grande Ronde, Imnaha, and Salmon rivers), and deep water redds were intensively searched using underwater video. Using actual adult counts for those years, fish-per-redd ratios ranged from 3.0 to 5.5, with an average prespawn mortality of 0.5. However, counts at Lower Granite Dam may not represent true escapement because of some losses due to fallback through the dam. Using a fallback estimate of 35% (Mendel 1992) to adjust escapement, fish-per-redd estimates ranged from 2.0 to 3.6, with an average prespawn mortality of 0.29. The range of prespawning mortality is comparable to those reported in Chapman et al. (1994). We believe that the long migration required of Snake River fall chinook that might spawn upstream of the HCC would indicate similar prespawning losses.

Although we recognize that the egg-to-smolt survival rates of spring chinook and steelhead can be considerably higher than our LRE and HRE estimates of 0.05 and 0.02, respectively, we consider higher rates to be a product of underescapement. ODFW (1987) offered egg-to-smolt survival rates for spring chinook that ranged from 0.03 for full escapement to almost 0.12 for an escapement that was 10% of maximum. The same source showed egg-to-smolt survival rates for steelhead that ranged from 0.0075 to 0.03 for full and 10% escapements, respectively. However,

4 Based on fall conditions in the Methow River, 543 redds probably constitutes a full redd count. The escapement information was based on observations at an electric weir and trap in the lower river.

Page 20 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives the high-end survival rates come at a cost to maximum smolt output. Such survival rates indicate biological compensation “on the left side of the stock-recruit curve,” where stocks may persist, but at levels far below their maximum potential. Alternatively, stocks may go to extinction where SARs are very low.

Other factors that would affect egg-to-smolt survival include interspecific interactions within the subbasin spawning and rearing areas. Production potential estimates in Chapter 8 (Chapman and Chandler 2001b) took into account habitat quality, but could not account for the potential effects of established resident fish populations. The subbasins upstream of Hells Canyon have been removed from anadromy for approximately 40 to over 100 years. Resident populations of salmonids and other species have become well established in these basins. Introduced exotic salmonids and other fish species have also become well established in many of these basins. For example, eastern brook trout are well established throughout much of the Weiser River basin, and smallmouth bass and walleye are present in Salmon Falls Creek. The establishment of exotic populations would likely decrease egg-to-smolt survival relative to stocks that have adapted to environmental conditions and have potentially less predation and competition pressures.

Our estimates for prespawning losses for spring chinook ranged from 0.2 for the LRE assumption to 0.3 for the HRE assumption. Bjornn (1990) estimated prespawning loss in spring/summer chinook in the Snake River as 0.45 when only Ice Harbor Dam was in the lower Snake River. Later, when four dams were present in the lower Snake River, the rate increased to about 0.55. When Chapman et al. (1991) reviewed information on prespawning mortality, they provisionally estimated a rate of 0.3 to 0.4.

4.2.3. The “No-Fishing” Assumption

Our assumption of no fishing in the Columbia and Snake rivers is simplistic. Even though listing under the Endangered Species Act has aimed to protect wild Snake River spring chinook, fall chinook, and steelhead, fisheries have taken these species. Early spring fisheries aimed at Willamette River spring chinook and subsistence and ceremonial fisheries in Zone 6 have annually harvested listed Snake River spring chinook, albeit at relatively low rates. Listed fall chinook have been taken in significant numbers in the fall fishery in Zone 6. Fisheries in Zone 6, and sometimes in Zones 1 through 5, take Snake River steelhead. Even incidental catch-and- release of wild spring/summer chinook and wild steelhead in Idaho result in some post-catch mortality.

Incorporation of fishing mortality at any exploitation rate would reduce the return of adults to Lower Granite Dam, Hells Canyon Dam, and to subbasins and river reaches upstream of Hells Canyon Dam. Our scenarios, even without considering downriver fishing, indicate that salmon and steelhead from most subbasins cannot fully seed habitat there.

4.3. Subbasin Smolt Production

As noted earlier, some conservative assumptions govern our model output for survival rates. For example, we could have used “good” habitat characterization and resulting paradigms to estimate smolt outputs instead of “fair” or “poor” designations (Chapter 8, Chapman and Chandler

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2001b). However, that change would not affect whether subbasin populations sustain themselves or fully seed habitat. Self-sustenance depends mostly on what happens to smolts that leave the subbasin or river reach. In our modeling, interdam and prespawning loss of adults, loss of smolts during their migration to the Lower Granite tailrace, and SARs for smolts from Lower Granite Reservoir determine whether subbasins and river reaches can maintain self-sustaining stocks in fully seeded habitat. We believe that we offer a reasonable range of assumptions for these parameters.

We did assume that the entire production potential of a subbasin would survive to the mainstem migration corridor. However, losses of smolts outmigrating would be expected, and could be substantial, within the subbasin before the smolts could reach the mainstem corridor. If subbasin losses were accounted for, our estimates of smolts arriving at Lower Granite Dam could be much less. All of the basins we examined with our model support extensive irrigation, with the exception of Indian Creek and the Wildhorse River (see Chapter 4, Chandler and Chapman 2001). An irrigation diversion screening program would be necessary in any reintroduction program intended for self-sustaining populations.

Smolts migrating out to the mainstem corridor would also be reduced by possible predation within the subbasins. Most of the subbasins support predators at some level. For example, Chandler et al. (2001b) documented the presence of northern pikeminnow, smallmouth bass, channel catfish, fluvial rainbow trout, and bull trout in Lower Pine Creek. Northern pikeminnow and smallmouth bass are ubiquitous throughout the Snake River and throughout at least the lower end of the tributaries below Shoshone Falls. Estimating the extent of predation is difficult because predation varies depending on outmigration conditions such as flow quantity and water temperature.

We did not model survival for production areas upstream of dams that exist within the subbasin. These areas include the Powder, Burnt, Malheur, Owyhee, Payette, and Boise rivers (see Chapter 4, Chandler and Chapman 2001). However, with the basins that we modeled and with our assumption that all subbasin production would survive to the mainstem migration corridor, the results for the basins we modeled give a good indication of survival and expected adult returns. It is clear that any basin above Brownlee Reservoir and below Swan Falls Dam would not be able to sustain full production for any of our SAR or required escapement assumptions. Reintroducing anadromous fish above existing barriers in these basins requires implementation of a collection and transport program. For example, a collection facility at Black Canyon Dam on the Payette River or at Arrowrock Dam on the Boise River would be necessary for these basins. The potential success of this type of program, at least for the South Fork and Middle Fork Payette River system with collection at Black Canyon Dam, is represented by our model run of a collection facility at C.J. Strike Dam to collect outmigrating smolts from the Bruneau River (Section 3.4.4 and Figure 8). At an assumed 80% collection efficiency, adult returns for spring chinook under the LSAR assumptions were not enough to meet required escapement to maintain basin production. However, under the higher SAR assumptions, returns exceeded the level required if the LRE assumptions were used. However, as discussed above, under the HSAR assumptions, the HRE assumptions may be the most appropriate. A collection facility at Arrowrock Dam would not be as comparable to the Bruneau River example as the Payette River example. In the Boise River example, the 20% of smolts that would not be collected would need to migrate through another large reservoir and migrate through the lower Boise River before

Page 22 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives reaching the mainstem Snake River. Anticipated smolt survival would be less than that modeled for the Bruneau River.

The modeling also suggests that if adults were transported from Hells Canyon Dam to the production area, fewer adult returns would be required. Transporting adults would likely be necessary in basins such as the Payette and Boise. Otherwise, extensive upstream passage facilities would need to be constructed within the subbasin to pass fish over many irrigation diversion dams and through large mainstem dams before they could reach the production area. However, even with transportation, it is still questionable whether the basin production potential could be self-sustained.

4.4. Hatchery Supplementation

Managers might be able to circumvent some life-stage mortality by taking adults at Hells Canyon Dam to support hatchery operations that would include smolt releases. Regardless of the species or production area, any reintroduction program would likely require hatchery supplementation well into the foreseeable future.

A hatchery program would partially avoid natural losses associated with interdam mortality (upstream of Hells Canyon Dam), some prespawning loss, and most egg-to-smolt mortality. For example, spring chinook at Rapid River Hatchery have approximately a 16% prespawn mortality rate and 75% egg-to-smolt survival rate (P. Abbott, IPC, unpubl. data). Hatchery supplementation would make any development of subbasin-adapted stocks upstream of Hells Canyon Dam unlikely. Alternatively, managers could trap adults in subbasins and return hatchery-reared progeny to the same subbasins as smolts, providing some opportunity for adaptation of subbasin stocks. However, depending on the basin, significant numbers of smolts would need to be released in the subbasin to offset mortality associated with downstream passage. In such basins, transfer of hatchery smolts to an acclimation facility with pumped river water for some time before transporting to Hells Canyon Dam may increase the chances of natural returns to the basin if in-river passage of adults were provided. This option would still maintain high enough smolt survival rates to benefit from the hatchery program.

Under the LSAR assumptions, the number of smolts that could be produced by the estimated escapement was well below the production area potential. To achieve required adult levels, a high proportion of smolts arriving at Lower Granite Dam would be, by necessity, of hatchery origin. For example, Scenario 5A had the highest survival rate of spring chinook smolts arriving at Lower Granite Dam. However, under the LSAR and LRE assumptions, approximately 47% of the smolts would need to be of hatchery origin. An additional number of smolts would be required to supply enough extra adult returns to maintain the hatchery program and maintain natural spawning in the basin at full production. Using the HSAR and LRE assumptions, 17% of the smolts arriving at Lower Granite Dam would need to be of hatchery origin, plus additional smolts would be necessary to provide enough adults to maintain the hatchery program.

Reintroducing fall chinook in the Walters Ferry Reach would require a more extensive hatchery program than would reintroducing spring chinook in the Weiser River. Under Scenario 5A, approximately 80% of the smolts arriving at the Lower Granite tailrace would need to be of

Hells Canyon Complex Page 23 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company hatchery origin under the LSAR and LRE assumptions. Under the HSAR and LRE assumptions, approximately 58% of the smolts would need to be of hatchery origin to maintain high enough adult returns to maintain basin production. Additional smolts would be required to retain enough adults to maintain the hatchery program. The number of adults required for the hatchery program would depend on whether smolts were released for in-river passage or held on site for acclimation and then transported to the tailrace of Hells Canyon Dam.

4.5. Costs of Reintroduction

4.5.1. Facilities

Each reintroduction scenario assumes bypass and/or collection facilities at some or all of the dams involved in the scenario. With the exception of Brownlee reservoir and dam, survival estimates in each of the scenarios assume that reservoir passage to the tailrace is equal (on a per kilometer basis) to that observed for Lower Granite reservoir and dam. Lower Granite Dam facilities are state-of-the-art approaches for fish collection and bypass for large mainstem dams. Whether or not the assumption of comparable survival could be achieved is unknown. Chapter 9 (Aurdahl et al. 2001) provides conceptual cost estimates of passage facilities that may be appropriate for the HCC dams. Aurdahl et al. (2001) acknowledged that adequate detail was not included in the design specifics of those facilities to perform a detailed cost estimate based on precise material quantities and labor expenses for fabrication and installation. Their estimates were developed from estimated unit costs derived from the actual construction costs of similar facilities, vendor input for large components, standard industry cost guides, and engineering judgment. They did not estimate the cost of facilities upstream of Brownlee Dam, such as Swan Falls and C.J. Strike dams. For the basis of estimating costs associated with the reintroduction scenarios, we assumed that costs of facilities for Swan Falls and C.J. Strike projects would be comparable to those presented for Oxbow Dam. Oxbow Dam is comparable in height to C.J. Strike Dam. However, Swan Falls Dam is a lower head facility than Oxbow Dam, and therefore costs may be overestimated for Swan Falls Dam. Table 16 presents estimated costs for each of the scenarios.

In addition to the passage facilities, additional hatchery and acclimation facilities would be required. Hatchery supplementation would be required into the foreseeable future for most, if not all, of the scenarios we analyzed. The extent of the hatchery program would depend, of course, on the extent of reintroduction pursued. Given the limited potential for increased production at the existing IPC hatchery facilities, development of a supplementation program may require a commensurate reduction in fish produced for mitigation purposes under the terms of the Hells Canyon Settlement Agreement (Settlement Agreement 1980) or the acquisition of additional hatchery facilities. Other costs that would need to be considered would be associated with the various transportation options discussed in each of the scenarios. Currently, the costs of transporting smolts from existing IPC facilities is approximately $1.50 per mile, not including the amortized costs of the tanker trucks (P. Abbott, IPC, pers. comm.).

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4.5.2. Operations

In addition to the construction and operation and maintenance costs associated with the scenarios, we must consider the loss of revenue from energy generation associated with either the alternatives involving deep drawdown of Brownlee Reservoir or required spill at any of the facilities. These revenue losses would occur not only during the drawdown period but could extend through the summer months if the water supply is insufficient to refill Brownlee Reservoir. This latter condition would be especially pronounced during low-water years.

4.6. Feasibility of Reintroduction

Our estimates involved a relatively simplistic and deterministic model. We were not able to incorporate the effects of natural variation in environmental conditions that would further affect both our survival estimates and the ability of a population to establish and persist. Overall, we believe that we have made reasonable assumptions in our estimates of smolt survival to the Lower Granite tailrace from production areas upstream of Hells Canyon Dam. For many of the reasons discussed, we believe that the estimates present an optimistic look at what could be expected. Similarly, we have made reasonable assumptions regarding the level of escapement necessary to maintain the production levels presented in Chapter 8 (Chapman and Chandler 2001b). The primary goal of this study was to examine the feasibility of reintroducing anadromous fish above the HCC.

4.6.1. Goals of Reintroduction

Questions as to whether reintroduction is feasible can only be addressed given clearly stated goals of what is meant by reintroduction. The members of the Aquatic Resources Work Group (ARWG) defined the desired future conditions for anadromous fish as

Recovery and long-term persistence of self-sustaining, harvestable populations of anadromous fish, including Pacific lamprey, distributed across the species’ native range.

In addition to the desired future conditions, the ARWG defined several goals regarding anadromous fish. The goals include the following:

1. Allow sufficient escapement of adult anadromous fish past in-river and ocean fisheries

2. Restore and maintain suitable habitat conditions for all anadromous fish life history stages and strategies

a. Juvenile and adult migration corridors

b. Spawning and rearing habitat

3. Delist anadromous fish populations

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a. Supplementation of listed species

b. Conservation of genetic diversity

4. Maintain harvest opportunity, including continued production of nonlisted species

5. Maintain current distribution and restore distribution in previously occupied areas within species’ native range

Although these goals apply to populations of anadromous fish downstream of the HCC, they also apply to the areas upstream of the HCC with respect to restoring the distribution in previously occupied areas within the species’ native range. Presumably, these goals would be among the desired benefits of a reintroduction program. Clearly, significant changes would need to occur within both the historical area and in areas downstream of the HCC before these desired conditions and goals could be met.

4.6.2. Recovery and the Evolutionarily Significant Unit

Considerations of recovery as stated in the desired future conditions leads to the question—can reintroduction contribute to recovery of listed Snake River fish? Clearly, any stock characteristics that were unique to the historical production area upstream of Hells Canyon Dam have been lost forever. In that sense, true recovery is not achievable. Presumably, the role that reintroduction would play in the recovery of species listed under the Endangered Species Act would be to increase the number of populations within an Evolutionarily Significant Unit (ESU). This assumption implies that brood sources used for reintroduction would be part of the ESU. For Snake River ESUs, this restriction would limit the source to those hatchery stocks whose natural progeny are currently considered part of the ESU or wild fish from the ESU. For example, Lyons Ferry Hatchery for fall chinook salmon and the Oxbow Hatchery stock for steelhead could be used (Chapter 10, Chandler and Abbott 2001). However, for Snake River spring/summer chinook salmon, determining brood stock becomes more problematic. Rapid River stock, which originated from areas above Hells Canyon Dam, is not considered part of the ESU (Chapter 10, Chandler and Abbott 2001). The only hatchery stocks considered part of the ESU for spring/summer chinook are within the Salmon River basin.

Conservation theory suggests that increased numbers of populations within an ESU increases the viability of an ESU by reducing exposure to catastrophic events, and by contributing to environmental, demographic and genetic variation and diversity (McElhany et al. 2000). If self- sustaining populations were established upstream of the HCC, they likely would contribute to the recovery and viability of an ESU. However, a population in this context is one that is independent and cannot be substantially altered by exchanges of individuals with other populations (McElhany et al. 2000). It is evident that even under higher SARs, populations of anadromous fish upstream of the HCC could not persist without significant supplementation by hatchery fish. A population that depends on naturally spawning hatchery fish for its survival is not viable and cannot be considered to be independent from the hatchery component (McElhany et al. 2000). In the case of Snake River fall chinook, the same hatchery source that is currently heavily used to supplement the population of natural/wild fall chinook salmon would also be required for use for reintroduction. In that context, establishing fall chinook upstream of the

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HCC would not contribute to recovery, at least by means of increasing the number of populations within an ESU. Furthermore, additional hatchery fish in the system may further put at risk other listed ESUs by potentially increasing pathogen exposure, predation, competition, and straying such that the risks may outweigh the benefit (Hard et al. 1992). In addition, the potential of introducing pathogens to resident populations of salmonids cannot be overlooked, a risk that can never be clearly known (see Chapter 10, Chandler and Abbott 2001).

4.6.3. Ecosystem Recovery

Recovery under the Endangered Species Act is not limited to recovery of natural populations. It also includes recovery of the ecosystems on which the populations depend. This latter factor coincides with the second ARWG goal of restoring and maintaining anadromous fish habitat. Production areas upstream of the HCC are in generally poor condition, especially those areas that mainstem passage above the HCC would make immediately accessible to anadromous fish. Most of the production areas that are in “fair” to “good” condition are upstream of tributary dams and relatively high up in the tributary basins. As we noted in Chapters 4 (Chandler and Chapman 2001) and 5 (Chandler et al. 2001a), additional facilities for upstream and/or downstream passage to access these areas would be needed. Chapters 4 (Chandler and Chapman 2001) and 5 (Chandler et al. 2001a) also identify how land uses and water management have either altered or reduced the instream flows of most tributary basins. Numerous unscreened water diversions that are distributed throughout the basin would contribute to losses of anadromous fish and reduce the likelihood of success for a reintroduction program.

Ecosystems downstream of the HCC strongly influence viability of potential reintroductions of anadromous fish upstream of the HCC. The migration corridor, estuary, nearshore ocean, and distant ocean environments, as well as fishing intensity, regulate SARs. The importance of these influences is evident in our analysis of survival and adult returns in the free-flowing river scenario. Under the LSAR assumptions, adult returns were inadequate to maintain basin production, even in the absence of fishing mortality in Zones 1 through 6 of the Columbia River. Such results with the LSAR estimates should not be surprising given the status of wild/natural populations downstream of the HCC. These results imply that SARs must improve if recovery upstream is to be expected. Furthermore, if conditions downstream (factors regulating SARs) of the HCC improve such that higher SARs can result, benefits to existing populations would be expected. Such a benefit could in itself lead to recovery.

Many ecosystem components that regulate SARs lie outside human control. Interdecadal and interannual variability in physical oceanographic conditions offer but one example (Hare and Francis 1995). A report by the Intergovernmental Panel on Climate Change (IPCC 2001) showed substantial warming over the past 100 years, with accelerated warming in the 1990s. The level of the sea surface has risen by between 0.1 and 0.2 m, and ocean heat content has increased. Anthropogenic activity appears responsible for most of the global temperature increase over the past 50 years. A National Academy of Science report (Commission on Geosciences, Environment and Resources 2000) concluded that warming of surface temperature over the past 20 years is undoubtedly real and occurred at a rate substantially greater than the average warming during the twentieth century. Research has demonstrated that the average thickness of Arctic ice declined from more than 10 ft in the 1950s to about 6 ft in the late 1990s. Melting at

Hells Canyon Complex Page 27 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company this rate would lead to an open Arctic by about 2060, with profound implications. “Populations of humans, small and large mammals, fish and other ocean dwellers, and birds would face a rate of environmental change unlike any seen since the end of the last ice age” (MacDonald 2001). MacDonald (2001) warns that warming may accelerate change in ways not readily predicted.

Quite apart from oceanographic changes caused by global warming, we would expect continued warming to have severe consequences for salmon and steelhead populations in the Snake River basin. The most conservative model prediction is for a temperature rise of 1 °C by 2060, and most models predict a rise of closer to 2 °C (IPCC 2001). High-temperature isopleths that determine utility of streams for salmonids (e.g., for spawning and rearing) would move upstream, reducing usable habitat. Temperatures in the migration corridor would increase, with influences on salmonid behavior, pathogens, and predator populations. For two periods with relatively warm spring-summer water temperatures in the Columbia River (1933–1946, 1978−1996), Petersen and Kitchell (2001) predicted northern pikeminnow predation 26 to 31% higher on salmonids than in a cold period (1947–1958). For the warmest year that they examined, they also predicted 68 to 96% higher predation compared with the coldest year.

While human activities such as reduced reliance on fossil fuels may slow global warming, time lags and societal inertia make such influence only theoretical to date. Recovering the ecosystems formerly used by anadromous fish upstream of the HCC will be a task that cannot be ignored in the evaluations of feasibility. Passage alone will do nothing to recover or restore anadromous fish upstream of the HCC and would have an extremely high price tag. This conclusion is similar to that reached by participants in a workshop conducted by Battelle Northwest National Laboratories and the U.S. Geological Survey (Battelle and USGS 2000). They concluded that restoring normative processes, such as reestablishing natural flow regimes and maintaining geomorphic features common to alluvial floodplains, is required for recovery of anadromous salmonids dependent on mainstem habitats.

Recovery of ecosystems that is within human control would require enormous societal commitment. Lackey (2001) suggested that there is little tangible evidence that people are willing to make the substantial personal or societal changes necessary to restore large runs of salmon. An example of positive movement toward ecosystem recovery in the Snake River basin is the ongoing process of implementing reductions of total maximum daily loads (TMDL), a process intended to reduce pollutant sources to waters in the basin. Although the intentions of the TMDL process are good, the successful implementation and benefit of such a process have yet to be seen. Even if they are seen, it will likely be many years from now. However, the TMDL process alone, even if successful, will not result in full ecosystem recovery. For example, the TMDL will not significantly reduce high water temperatures upstream of the HCC. Riparian habitat recovery on a large geographic scale is essential for ecosystem recovery. Connectivity of habitats fragmented by low instream flows, water diversions, and tributary and mainstem dams is also critical to ecosystem recovery. Without ecosystem recovery, reintroduction with the goal of recovering anadromous populations is not feasible.

4.6.4. Harvest Potential

The fourth goal listed by the ARWG does not imply reintroduction for purposes of recovery. Rather, it specifically targets nonlisted fish production for purposes of harvest. Presently, IPC

Page 28 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives mitigation hatchery programs allow excess hatchery fish to be transferred to the areas above the HCC for sport harvest. These areas have included the Boise and Payette rivers and Hells Canyon Reservoir. Such programs could be expanded with additional hatchery production. While not reintroduction in the sense of expanding the present distribution or playing a role in recovery, additional hatchery inputs upstream of the HCC would provide increased harvest opportunities in the historic distribution area. As a prerequisite to such programs, pathogen risk should be considered and baseline pathogen monitoring might be conducted. Risks of pathogen introduction cannot be defined, but must be accepted (Chapter 10, Chandler and Abbott 2001).

Translocation of excess hatchery fish offers a terminal fishery at relatively modest cost without the high uncertainty of success of complete passage. Nor would it require the extensive transportation that would be involved with some reintroduction scenarios, ones in which increased smolt survival would need to be considered.

One argument against such translocation programs could be the increased number of hatchery fish in the system. However, that same argument would apply to attempts to establish self- sustaining populations. It is clear that either type of program could not be sustained without additional hatchery fish in the system. However, this type of translocation program, because it is a terminal fishery, would not have the very high cost and high uncertainty of success associated with complete passage, nor would it require as extensive a transportation component as would some reintroduction scenarios where efforts to increase smolt survival need to be considered.

Some societal groups continue to promote increased reliance on hatchery outputs of salmon and steelhead. However, all increases in hatchery production for enhancing harvest inevitably conflict with conservation objectives aimed at wild/natural stocks (e.g., those in the Middle Fork Salmon River and other wilderness streams) as long as the gill net remains the primary gear used in Zones 1 through 6 fisheries. While fishery managers in the Columbia River basin have minimized kill of sport-caught wild/natural steelhead by allowing retention of only marked fish of hatchery origin, kill fisheries persist for wild spring/summer chinook, fall chinook, and steelhead in the mainstem Columbia River. If wild/natural stocks in the Snake River basin are to sustain themselves, agencies and tribes must devise ways to release alive most or all upriver wild/natural salmon and steelhead captured in Zones 1 through 6. That caveat certainly holds for tributary wild stocks downstream of the HCC and would also apply to any expectation for development of self-sustaining tributary populations upstream of the HCC (as noted earlier, an expectation dependent on HSARs and LREs).

4.6.5. Marine-Derived Nutrients

Other discussions about the potential benefits of reintroduction that are not directly represented in the ARWG’s goals for anadromous fish recovery relate to some intrinsic benefits, regardless of whether returns are naturally produced or come from hatchery releases. Such intrinsic benefits could include restoring some level of a historical trophic structure to some of these basins or injecting long-absent marine-derived nutrients into the basin. Spawning salmon and their carcasses were once an integral component of aquatic and terrestrial habitats. Loss of anadromous escapement has reduced nutrient supply and productivity in some tributary basins (Cederholm et al. 1999).

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However, reintroduction of marine nutrients does not require upstream and downstream passage at mainstem dams. Simply expanding the existing hatchery program and translocation of excess adults, either as live fish or as carcasses, could achieve the goals of the program. Translocation of live fish would require production of more hatchery fish. Outplanting carcasses alone would not necessarily require an increase in the present hatchery production. For simply supplying carcasses for inputs to priority tributaries upstream of the HCC, existing hatchery programs would probably suffice.

5. SUMMARY AND CONCLUSIONS

Cleary, the issue of reintroduction raises many uncertainties. Reintroduction for the purposes of recovery of salmon and steelhead listed under the Endangered Species Act does not appear feasible unless very significant societal commitment develops for ecosystem recovery. Furthermore, unless average SARs downstream of the HCC improve very substantially over those of the early 1990s, reintroduction is quite infeasible. The same factors that limit anadromous fish downstream would also limit success of reintroduction upstream of the HCC. Even with substantial increases in SARs, most of the reintroduction scenarios that we examined would not permit self-sustaining populations of anadromous fish to develop in many subbasins.

Very significant steps toward ecosystem recovery need to occur upstream of the HCC. Such ecosystem recovery should be an immediate priority even before reintroduction. Along with that priority must come the realization that we (society) cannot turn back the clock—that human population growth will continue and we will not be able to recover all that was. Lackey (2001) asked the following question of fishery scientists:

Should we perpetuate the delusion that the Pacific Northwest will (or could, absent pervasive life-style changes) support wild salmon in significant numbers given the current trajectory of the region’s human population growth coupled with most individuals’ unwillingness to reduce substantially their consumption of resources and standard of living?

Managers must have realistic expectations for what can be accomplished in reintroducing anadromous fish. Limited resources could be better directed, at least in the short term.

We suggest that primary action should be directed at protecting and maintaining the remaining strongholds. Secondarily, we would aim at recovering and enhancing the areas that have the greatest potential for at least partial recovery. Many of these necessary actions go beyond the scope of Idaho Power and relicensing of the HCC; they would involve a large group of societal interests and commitment. These actions should include efforts to increase escapements in habitats for all anadromous fish downstream of the HCC. For example, fall chinook habitat in the Snake River downstream of the HCC is currently significantly underseeded (Groves 2001, Connor et al. 2001), as are populations of other anadromous fish.

The viability of native resident fish populations upstream of the HCC depends on ecosystem recovery. Examples most immediately associated with the HCC are white sturgeon in the reach

Page 30 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives below Swan Falls Dam (Lepla et al. 2001) and bull trout in Indian and Pine creeks (Chandler et al. 2001b, Pratt 2001). Many other redband habitats upstream of the HCC can be markedly improved, especially by eliminating livestock access to riparian zones. Anadromous fish may be a part of the ecosystem recovery necessary for resident fish. However, in the short term, these white sturgeon and bull trout populations face limiting factors more dire than the loss of nutrients caused by lack of anadromous fish. In the short term, the lost nutrients could be replaced with programs such as carcass outplanting. In the mainstem Snake River, the nutrient load is too high, a condition that has contributed to the degradation of habitats (Chapter 5, Chandler et al. 2001a).

Many of the more immediate actions that would be required to recover native fish would also be needed before reintroduction of anadromous fish could succeed. In the short term, we have much to learn regarding factors that will affect successful reintroduction. Our assumptions with respect to tributary and mainstem habitats (Chapters 4 [Chandler and Chapman 2001] and 5 [Chandler et al. 2001a]), production potential (Chapters 7 [Chapman and Chandler 2001a] and 8 [Chapman and Chandler 2001b]), survival through reservoirs and free-flowing sections (this chapter), and incubation survival in the mainstem Snake River (Chapter 5 [Chandler et al. 2001a]) all impinge on feasibility of reintroduction of anadromous salmonids. Future study should address these uncertainties in conjunction with implementation of measures to recover native salmonids and their habitat in basins such as Pine and Indian creeks. Studies of mainstem production areas could continue regarding intragravel conditions in conjunction with measures implemented in the ongoing TMDL process to improve water quality in the mainstem Snake River.

6. LITERATURE CITED

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Achord, S., D. Kamikawa, B. Sandford, and G. Matthews. 1996. Monitoring the migrations of wild Snake River spring/summer chinook salmon smolts, 1995. Annual report 1995. Coastal Zone and Estuarine Studies Division, National Marine Fisheries Service and Bonneville Power Administration. Project No. 91-28, Contract No. 91BP18800.

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Chandler, J. A., and D. Chapman. 2001. Existing habitat conditions of tributaries formerly used by anadromous fish. In: J. A. Chandler, editor. Chapter 4. Feasibility of reintroduction of anadromous fish above or within the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise, ID. Technical Report E.3.1-2.

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Chapman, D., and J. A. Chandler. 2001a. Estimators of potential anadromous fish smolt yield. In: J. A. Chandler, editor. Chapter 7. Feasibility of reintroduction of anadromous fish above or within the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise, ID. Technical Report E.3.1-2.

Chapman, D., and J. A. Chandler. 2001b. Potential smolt yield of anadromous fish from subbasins above the Hells Canyon Complex. In: J. A. Chandler, editor. Chapter 8. Feasibility of reintroduction of anadromous fish above or within the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise, ID. Technical Report E.3.1-2.

Chapman, D., A. Giorgi, M. Hill, A. Maule, S. McCutcheon, D. Park, W. Platts, K. Pratt, J. Seeb, L. Seeb, and F. Utter. 1991. Status of Snake River chinook salmon. Don Chapman Consultants, Inc. Report to: Pacific Northwest Utilities Conference Committee.

Chapman, D., A. Giorgi, T. Hillman, D. Deppert, M. Erho, S. Hays, C. Peven, B. Suzumoto, and R. Klinge. 1994. Status of summer/fall chinook salmon in the mid-Columbia region. Don Chapman Consultants, Inc., Boise, ID. 411 p. plus appendices.

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Williams, J., and T. Bjornn. 1998. Fall chinook salmon survival and supplementation studies in the Snake River and lower Snake River reservoirs, 1996. Annual report 1996. Project Nos. 93-029 and 91-029, Contract Nos. DE-AI79-93BP10891 and DE-AI79-93BP21708. Prepared for: U.S. Army Corps of Engineers and Bonneville Power Administration.

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Table 1. Number of spring/summer chinook and steelhead PIT-tagged and released at the Salmon River trap near Riggins and at the Snake River trap near Lewiston, recovered at four downstream dams (Lower Granite, Little Goose, Lower Monumental, and McNary), and rate of recovery. Data are from Buettner and Brimmer (1994, 1995, 1996, 1998).

1 2 3 (2/1) Year Group Snake River Trap Salmon River Trap Estimated Survival Rate

1993 Wild steelhead 2,414/2,867 = 0.84 689/ 902 = 0.76 0.90

1993 Hatchery steelhead 2,236/2,521 = 0.89 1,372/1,641 = 0.84 0.94

1993 Wild chinook 828/1,125 = 0.74 1,614/2,169 = 0.74 1.00

1993 Hatchery chinook 2,210/3.203 = 0.69 1,919/3,138 = 0.61 0.88

1994 Wild steelhead 2,100/2,820 = 0.75 347/515 = 0.67 0.89

1994 Hatchery steelhead 1,683/3,234 = 0.52 1,280/2,575 = 0.50 0.96

1994 Wild chinook 618/908 = 0.68 1,803/2,913 = 0.62 0.91

1994 Hatchery chinook 1,769/2,833 = 0.62 1,815 /3,616 = 0.50 0.81

1995 Wild steelhead 1,297/1,537 = 0.84 343/435 = 0.79 0.94

1995 Hatchery steelhead 1,897/2,244 = 0.85 1,259/1,556 = 0.81 0.95

1995 Wild chinook 1,673/2,067 = 0.81 2,967/3,937 = 0.75 0.93

1995 Hatchery chinook 2,872/3,927 = 0.73 3,251/5,074 = 0.64 0.88

1996 Wild steelhead 509/ 655 = 0.78 183/251 = 0.73 0.94

1996 Hatchery steelhead 1,085/1,363 = 0.80 967/1,410 = 0.69 0.86

1996 Wild chinook 618/842 = 0.73 882/1,425 = 0.62 0.85

1996 Hatchery chinook 985/1,450 = 0.68 1,363/2,701 = 0.50 0.74

Mean survival all years chinook 0.88

Mean survival all years steelhead 0.92

Hells Canyon Complex Page 39 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 2. Description of reintroduction scenarios evaluated.

Scenario Scenario Description 1 Free-flowing river for downstream passage, in-river passage for adults 2 Bypass smolts at Oxbow and Hells Canyon dams, in-river passage for adults 3A Brownlee Reservoir 89-ft maximum drawdown, no smolt bypass facilities at Brownlee Dam, in-river passage for adults 3B Brownlee Reservoir 21-ft maximum drawdown, no smolt bypass facilities at Brownlee Dam, in-river passage for adults 4 Brownlee Reservoir 21-ft maximum drawdown, collection facility with 50% efficiency at the upstream end of Brownlee Reservoir, no smolt bypass facility at Brownlee Dam, in-river passage for adults 5A Brownlee Reservoir 89-ft maximum drawdown, collection facility at Brownlee Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, in-river passage for adults 5B Brownlee Reservoir 21-ft maximum drawdown, collection facility at Brownlee Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, in-river passage for adults 6A Smolt bypass facilities at C.J. Strike Dam, collection facility at Swan Falls Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, Brownlee Reservoir 89-ft maximum drawdown, no smolt bypass facility at Brownlee Dam, in-river passage for adults 6B Smolt bypass facilities at C.J. Strike Dam, collection facility at Swan Falls Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, Brownlee Reservoir 21-ft maximum drawdown, no smolt bypass facility at Brownlee Dam, in-river passage for adults 7A Smolt bypass facilities at C.J. Strike Dam, collection facilty at Swan Falls Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, Brownlee Reservoir 89-ft maximum drawdown, collection facility at Brownlee Dam with 80% efficiency and transport, in-river passage for adults 7B Smolt bypass facilities at C.J. Strike Dam, collection facility at Swan Falls Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, Brownlee Reservoir 21-ft maximum drawdown, collection facility at Brownlee Dam with 80% efficiency and transport, in-river passage for adults 8A Smolt bypass at all projects, Brownlee Reservoir 89-ft maximum drawdown, 100% bypass at Brownlee Dam 8B Smolt bypass at all projects, Brownlee Reservoir 21-ft maximum drawdown, 100% bypass at Brownlee Dam 9A Collection facility at C.J. Strike Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, bypass facilities at all projects, Brownlee Reservoir 89-ft maximum drawdown, 100% bypass at Brownlee Dam 9B Collection facility at C.J. Strike Dam with 80% efficiency and transport to the Hells Canyon Dam tailrace, bypass facilities at all projects, Brownlee Reservoir 21-ft maximum drawdown, 100% bypass at Brownlee Dam

Page 40 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

Table 3. Mortality coefficients and survival estimates of spring chinook salmon, steelhead, and fall chinook salmon for different reaches of the Snake River.

Mortality Coefficients In-Reach Survival Estimates Spring Fall Spring Fall River Reach Chinook Steelhead Chinook Chinook Steelhead Chinook

Rock Creek to Upper Salmon Falls Dam –0.0284 –0.0185 –0.0738 0.9720 0.9816 0.9289 Cedar Draw Creek to Upper Salmon Falls Dam –0.0206 –0.0134 –0.0535 0.9796 0.9867 0.9479 Salmon Falls Creek to Upper Salmon Falls Dam –0.0064 –0.0042 –0.0166 0.9936 0.9958 0.9835 Upper Salmon Falls Dam to Lower Salmon Falls Dam –0.0208 –0.0236 –0.0527 0.9794 0.9767 0.9487 Billingsley Creek to Lower Salmon Falls Dam –0.0016 –0.0018 –0.0041 0.9984 0.9982 0.9960 Lower Salmon Falls Dam to Bliss Reservoir –0.0085 –0.0056 –0.0221 0.9915 0.9945 0.9781 Malad River to Bliss Reservoir –0.0057 –0.0037 –0.0148 0.9943 0.9963 0.9854 Bliss Reservoir to Bliss Dam –0.0144 –0.0163 –0.0365 0.9857 0.9838 0.9642 Bliss Dam to C.J. Strike Reservoir –0.0391 –0.0255 –0.1014 0.9617 0.9748 0.9035 RKM 874 to C.J. Strike Reservoir –0.0192 –0.0125 –0.0498 0.9810 0.9876 0.9514 C.J. Strike Reservoir to C.J. Strike Dam –0.0834 –0.0943 –0.2107 0.9200 0.9100 0.8100 Bruneau River to C.J. Strike Dam –0.0208 –0.0236 –0.0527 0.9794 0.9767 0.9487 C.J. Strike Dam to Swan Falls Reservoir –0.0320 –0.0208 –0.0830 0.9685 0.9794 0.9204 RKM 772 to Swan Falls Reservoir –0.0156 –0.0102 –0.0406 0.9845 0.9899 0.9602 Swan Falls Reservoir to Swan Falls Dam –0.0192 –0.0218 –0.0486 0.9809 0.9785 0.9525 Swan Falls Dam to Snake River scoop trap –0.1271 –0.0829 –0.3301 0.8806 0.9204 0.7188 Walters Ferry to Snake River scoop trap –0.1094 –0.0713 –0.2840 0.8964 0.9311 0.7528 Owyhee River to Snake River scoop trap –0.0511 –0.0334 –0.1328 0.9502 0.9672 0.8757 Boise River to Snake River scoop trap –0.0511 –0.0334 –0.1328 0.9502 0.9672 0.8757 Malheur River to Snake River scoop trap –0.0241 –0.0157 –0.0627 0.9761 0.9844 0.9392 Payette River to Snake River scoop trap –0.0206 –0.0134 –0.0535 0.9796 0.9867 0.9479 Weiser River to Snake River scoop trap –0.0057 –0.0037 –0.0148 0.9943 0.9963 0.9854 Snake River scoop trap to Brownlee Dam (89-ft drawdown of Brownlee Reservoir) –0.6811 –0.6811 –0.8772 0.5060 0.5060 0.4159 Burnt River to Brownlee Dam (89-ft drawdown of Brownlee Reservoir) –0.4752 –0.4752 –0.6120 0.6218 0.6218 0.5423 Lower Snake River tributaries to Brownlee Dam (89-ft drawdown of Brownlee Reservoir) –0.3643 –0.3643 –0.4692 0.6947 0.6947 0.6255 Powder River to Brownlee Dam (89-ft drawdown of Brownlee Reservoir) –0.1346 –0.1346 –0.1734 0.8740 0.8740 0.8408 Snake River scoop trap to Brownlee Dam (21-ft drawdown of Brownlee Reservoir) –1.7888 –1.7888 –1.9866 0.1672 0.1672 0.1372 Burnt River to Brownlee Dam (21-ft drawdown of Brownlee Reservoir) –1.2480 –1.2480 –1.3860 0.2871 0.2871 0.2501 Lower Snake River tributaries to Brownlee Dam (21-ft drawdown of Brownlee Reservoir) –0.9568 –0.9568 –1.0626 0.3841 0.3841 0.3456 Powder River to Brownlee Dam (21-ft drawdown of Brownlee Reservoir) –0.3536 –0.3536 –0.3927 0.7022 0.7022 0.6752

Hells Canyon Complex Page 41 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 3. (Cont.)

Mortality Coefficients In-Reach Survival Estimates Spring Fall Spring Fall River Reach Chinook Steelhead Chinook Chinook Steelhead Chinook

Oxbow Reservoir –0.0529 –0.0599 –0.1337 0.9485 0.9419 0.8748 Wildhorse River to Oxbow Dam –0.0257 –0.0290 –0.0648 0.9747 0.9714 0.9372 Hells Canyon Reservoir –0.0673 –0.0762 –0.1702 0.9349 0.9267 0.8435 Indian Creek to Hells Canyon Dam –0.0641 –0.0725 –0.1621 0.9379 0.9300 0.8504 Pine Creek to Hells Canyon Dam –0.0593 –0.0671 –0.1499 0.9424 0.9351 0.8608 Hells Canyon Dam to Lower Granite Reservoir –0.1222 –0.0797 –0.3172 0.8850 0.9234 0.7282 Lower Granite Reservoir to Lower Granite Dam tailrace –0.0834 –0.0943 –0.2107 0.9200 0.9100 0.8100 RKM 772 to head of Swan Falls Reservoir –0.0407 0.9600 C.J. StrikeDam to head of Swan Falls Reservoir –0.0325 –0.01998 –0.08325 0.9680 0.9800 0.9200 C.J. Strike Reservoir Bruneau River arm to C.J. Strike Dam –0.0208 –0.0235 0.9790 0.9770 C.J. Strike Reservoir Snake River arm to C.J. Strike Dam –0.0834 0.0941 0.2106 0.9200 0.910 0.8100 RKM 874 to head of C.J. Strike Reservoir –0.04995 0.9510 Bliss Dam to head of C.J. Strike Reservoir –0.0397 –0.0244 0.9610 0.9760 Head of Bliss Reservoir to Bliss Dam –0.01443 –0.01629 0.9860 0.9840 Malad River to head of Bliss Reservoir –0.00355 0.9960 Lower Salmon Falls Dam to head of Bliss Reservoir –0.00866 –0.00533 0.9910 0.9950 Billingsley Creek to Lower Salmon Falls Dam –0.00044 0.9990 Upper Salmon Falls Dam to Lower Salmon Falls Dam –0.00939 –0.00577 0.9910 0.9940 Salmon Falls Creek to Upper Salmon Falls Dam –0.0065 –0.0040 0.9940 0.9960 Cedar Draw Creek to Upper Salmon Falls Dam –0.01288 0.9870 Rock Creek to Upper Salmon Falls Dam –0.0289 –0.0178 0.9720 0.9820

Page 42 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

Table 4. Required adult escapement of spring chinook necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions.

Transport Nontransport Subbasin LRE HRE LRE HRE

Pine Creek 650 1,392 Wildhorse River 419 898 437 946 Powder River (Eagle Creek) 445 953 482 1,055 Weiser River 722 1,547 784 1,715 Bruneau River 4,172 8,941 4,913 10,978

Table 5. Required adult escapement of steelhead necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions.

Transport Nontransport Subbasin LRE HRE LRE HRE

Pine Creek 516 1,215 Indian Creek 73 172 Wildhorse River 328 773 342 813 Powder River (Eagle Creek) 615 1,447 667 1,604 Weiser River 693 1,632 752 1,808 Bruneau River 3,312 7,793 3,900 9,568

Table 6. Required adult escapement of fall chinook necessary to replace smolt production from subbasin production areas with transport of adults from Hells Canyon Dam and nontransport (in-river passage of adults) under low required escapement (LRE) and high required escapement (HRE) assumptions.

Transport Nontransport Subbasin LRE HRE LRE HRE

Swan Falls Dam to Brownlee 8,149 23,768 8,842 26,336 Reservoir C.J. Strike Dam to Swan Falls 3,254 9,490 3,678 11,069 Reservoir Bliss Dam to C.J. Strike Reservoir 7,530 21,964 8,866 26,966

Hells Canyon Complex Page 43 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 7. Survival of spring chinook smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Scenario Pine Indian Wildhorse Powder Weiser Bruneau 1. Free-flowing river 0.79 0.78 0.76 0.72 0.61 2. Bypass at OXB and HCD 0.77 0.74 3A. 89-ft drawdown of Brownlee Reservoir, no bypass at 0.45 0.26 BRD 3B. 21-ft drawdown of Brownlee Reservoir, no bypass at 0.36 0.09 BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in 0.36 0.14 upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee Reservoir, 80% collection at 0.65 0.37 BRD 5B. 21-ft drawdown of Brownlee Reservoir, 80% collection at 0.52 0.12 BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 0.65 Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 0.62 Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 0.69 Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 0.65 Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown of Brownlee 0.30 Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown of Brownlee 0.10 Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown of Brownlee 0.70 Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at all projects, 21-ft drawdown of Brownlee 0.66 Reservoir, 100% bypass at BRD

Page 44 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

Table 8. Number of spring chinook smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Scenario Pine Indian Wildhorse Powder Weiser Bruneau

Subbasin production 58,473 37,736 40,007 65,008 375,517 1. Free-flowing river 46,375 29,485 30,514 46,944 230,305 2. Bypass at OXB and HCD 44,867 27,997 3A. 89-ft drawdown of Brownlee 17,924 16,767 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 14,399 5,539 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee 14,399 8,807 Reservoir, 50% collection in upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee 25,906 24,234 Reservoir, 80% collection at BRD 5B. 21-ft drawdown of Brownlee 20,812 8,005 Reservoir, 80% collection at BRD 6A. Bypass at CJS, 80% collection at 243,263 SFD, 89-ft drawdown of Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at 232,382 SFD, 21-ft drawdown of Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection, 258,633 at SFD, 89-ft drawdown of Brownlee Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at 242,396 SFD, 21-ft drawdown of Brownlee Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft 114,417 drawdown of Brownlee Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft 37,795 drawdown of Brownlee Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at 261,825 all projects, 89-ft drawdown of Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at 246,500 all projects, 21-ft drawdown of Brownlee Reservoir, 100% bypass at BRD

Hells Canyon Complex Page 45 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 9. Number of spring chinook adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Pine Wildhorse Powder Weiser Bruneau Scenario LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR 1. Free-flowing river 385 1,253 245 796 253 824 390 1,268 1,913 6,220 2. Bypass at OXB and HCD 373 1,212 233 756 3A. 89-ft drawdown of Brownlee Reservoir, no 150 484 139 452 bypass at BRD 3B. 21-ft drawdown of Brownlee Reservoir, no 120 389 46 150 bypass at BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in upper 120 389 148 480 Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee Reservoir, 80% 215 700 201 655 collection at BRD 5B. 21-ft drawdown of Brownlee Reservoir, 80% 173 562 66 216 collection at BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 2,022 6,570 Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 1,931 6,276 Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 2,150 6,986 Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 2,014 6,547 Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown 951 3,090 of Brownlee Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown 314 1,021 of Brownlee Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown of 2,176 7,072 Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at all projects, 21-ft drawdown of 2,049 6,658 Brownlee Reservoir, 100% bypass at BRD

Page 46 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

Table 10. Survival of steelhead smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Lower Snake Scenario Pine Indian Wildhorse Powder Tributaries Weiser Bruneau 1. Free-flowing river 0.83 0.82 0.82 0.81 0.79 0.78 0.70 2. Bypass at OXB and HCD 0.79 0.78 0.76 3A. 89-ft drawdown of Brownlee 0.46 0.36 0.26 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 0.37 0.20 0.09 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in 0.37 0.20 0.28 upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee Reservoir, 80% collection at 0.67 0.53 0.38 BRD 5B. 21-ft drawdown of Brownlee Reservoir, 80% collection at 0.54 0.29 0.13 BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft 0.68 drawdown of Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft 0.64 drawdown of Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 0.71 Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 0.67 Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown of Brownlee 0.33 Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown of Brownlee 0.11 Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown of Brownlee 0.72 Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at all projects, 21-ft drawdown of Brownlee 0.68 Reservoir, 100% bypass at BRD

Hells Canyon Complex Page 47 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 11. Number of steelhead smolts from subbasins upstream of Hells Canyon Dam arriving at Lower Granite tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Lower Snake Scenario Pine Indian Wildhorse Powder Tributaries Weiser Bruneau Subbasin production 23,234 3,295 14,774 27,678 15,683 31,204 149,048 1. Free-flowing river 19,192 2,718 12,086 22,288 12,460 24,247 104,111 2. Bypass at OXB and HCD 18,257 2,575 11,175 3A. 89-ft drawdown of Brownlee 12,598 5,673 8,193 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 10,120 3,173 2,706 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee 10,120 3,173 8,807 Reservoir, 50% collection in upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee 18,457 8,312 12,003 Reservoir, 80% collection at BRD 5B. 21-ft drawdown of Brownlee 14,827 4,596 3,965 Reservoir, 80% collection at BRD 6A. Bypass at CJS, 80% 100,660 collection at SFD, 89-ft drawdown of Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% 96,037 collection at SFD, 21-ft drawdown of Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% 106,059 collection at SFD, 89-ft drawdown of Brownlee Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% 99,143 collection at SFD, 21-ft drawdown of Brownlee Reservoir, 80% collection at BRD 8A. Bypass through all projects, 48,618 89-ft drawdown of Brownlee Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 16,059 21-ft drawdown of Brownlee Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, 107,561 bypass at all projects, 89-ft drawdown of Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, 101,050 bypass at all projects, 21-ft drawdown of Brownlee Reservoir, 100% bypass at BRD

Page 48 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives Table 12. Number of steelhead adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Lower Snake Pine Indian Wildhorse Powder Tributaries Weiser Bruneau Scenario LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR LSAR HSAR 1. Free-flowing river 159 518 23 73 100 327 185 602 104 337 201 655 865 2,812 2. Bypass at OXB and HCD 152 493 21 70 93 302 3A. 89-ft drawdown of Brownlee 104 340 47 153 68 221 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 84 273 26 86 23 73 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in upper 84 273 26 86 73 238 Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee 153 499 69 225 100 324 Reservoir, 80% collection at BRD 5B. 21-ft drawdown of Brownlee 123 400 38 124 33 107 Reservoir, 80% collection at BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 836 2,719 Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 798 2,594 Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of Brownlee 882 2,865 Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of Brownlee 824 2,678 Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown of Brownlee Reservoir, 404 1,313 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown of Brownlee Reservoir, 133 434 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown of 894 2,905 Brownlee Reservoir, 100% bypass at BRD 9B. CJS, 80% collection. Bypass at all projects, 21-ft drawdown, 100% 840 2,729 bypass at BRD

Hells Canyon Complex Page 49 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 13. Survival of fall chinook smolts from potential mainstem production areas upstream of Hells Canyon Dam arriving at the Lower Granite Dam tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Below Above Scenario Walters Ferry C.J. Strike C.J. Strike

1. Free-flowing river 0.33 0.30 0.25 2. Bypass at OXB and HCD 3A. 89-ft drawdown of Brownlee 0.10 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 0.03 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in 0.14 upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee 0.16 Reservoir, 80% collection at BRD 5B. 21-ft drawdown of Brownlee 0.05 Reservoir, 80% collection at BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of 0.44 0.32 Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of 0.43 0.32 Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of 0.45 0.33 Brownlee Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of 0.43 0.32 Brownlee Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown of Brownlee 0.12 0.11 Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown of Brownlee 0.04 0.04 Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown of 0.37 Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at all projects, 21-ft drawdown of 0.36 Brownlee Reservoir, 100% bypass at BRD

Page 50 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

Table 14. Number of fall chinook smolts from potential mainstem production areas upstream of Hells Canyon Dam arriving at the Lower Granite Dam tailrace under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Below Above Scenario Walters Ferry C.J. Strike C.J. Strike

Subbasin production 1,839,626 734,535 1,700,000 1. Free-flowing river 606,976 217,370 416,816 2. Bypass at OXB and HCD 3A. 89-ft drawdown of Brownlee 178,000 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 58,697 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee 248,869 Reservoir, 50% collection in upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee 301,961 Reservoir, 80% collection at BRD 5B. 21-ft drawdown of Brownlee 99,573 Reservoir, 80% collection at BRD 6A. Bypass at CJS, 80% collection at 323,099 552,347 SFD, 89-ft drawdown of Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at 314,778 538,121 SFD, 21-ft drawdown of Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at 331,746 567,128 SFD, 89-ft drawdown of Brownlee Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at 317,629 542,996 SFD, 21-ft drawdown of Brownlee Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft 87,435 192,389 drawdown of Brownlee Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft 28,832 63,441 drawdown of Brownlee Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at 635,729 all projects, 89-ft drawdown of Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at 615,693 all projects, 21-ft drawdown of Brownlee Reservoir, 100% bypass at BRD

Hells Canyon Complex Page 51 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

Table 15. Number of fall chinook adults returning to Hells Canyon Dam under nine reintroduction scenarios. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Walters Ferry Below C.J. Strike Above C.J. Strike Scenario LSAR HSAR LSAR HSAR LSAR HSAR 1. Free-flowing river 1,681 7,566 602 2,710 1,155 5,196 2. Bypass at OXB and HCD 3A. 89-ft drawdown of Brownlee 494 2,219 Reservoir, no bypass at BRD 3B. 21-ft drawdown of Brownlee 162 732 Reservoir, no bypass at BRD 4. 21-ft drawdown of Brownlee Reservoir, 50% collection in 689 3,102 upper Brownlee Reservoir, no bypass at BRD 5A. 89-ft drawdown of Brownlee Reservoir, 80% collection at 836 3,764 BRD 5B. 21-ft drawdown of Brownlee Reservoir, 80% collection at 276 1,241 BRD 6A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of 895 4,028 1,530 6,885 Brownlee Reservoir, no bypass at BRD 6B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of 872 3,924 1,491 6,708 Brownlee Reservoir, no bypass at BRD 7A. Bypass at CJS, 80% collection at SFD, 89-ft drawdown of 919 4,135 1,515 7,070 Brownlee Resevoir, 80% collection at BRD 7B. Bypass at CJS, 80% collection at SFD, 21-ft drawdown of 879 3,959 1,504 6,768 Brownlee Reservoir, 80% collection at BRD 8A. Bypass through all projects, 89-ft drawdown of Brownlee 242 1,090 534 2,398 Reservoir, 100% bypass at BRD 8B. Bypass through all projects, 21-ft drawdown of Brownlee 80 359 176 791 Reservoir, 100% bypass at BRD 9A. 80% collection at CJS, bypass at all projects, 89-ft drawdown 1,761 7,925 of Brownlee Reservoir, 100% bypass at BRD 9B. 80% collection at CJS, bypass at all projects, 21-ft drawdown 1,705 7,675 of Brownlee Reservoir, 100% bypass at BRD

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Table 16. Estimated facility construction and annual operation and maintenance (O&M) costs (in millions of dollars) for each of the reintroduction scenarios. Costs do not include the operational costs associated with the 89-ft or 21-ft Brownlee Reservoir drawdown options discussed in the text. BRD = Brownlee Dam, CJS = C.J. Strike Dam, HCD = Hells Canyon Dam, OXB = Oxbow Dam, and SFD = Swan Falls Dam.

Upstream1 Downstream Scenario Construction Annual O&M Construction Annual O&M Total6

1. Free-flowing river2

2. Bypass at OXB and HCD3 36 1.8 45.5 4.5 239 3. Above BRD, no bypass at 36 1.8 45.5 4.5 239 BRD 4. Above BRD, 50% collection at 77.7 6 79.1 8.1 509.3 upper Brownlee Reservoir, no bypass at BRD 5. Above BRD, 80% collection at 77.7 6 109.1 9 561.8 BRD4 6. CJS bypass, 80% collection 58.2 3 82.5 8.1 418.2 at SFD, no bypass at BRD4 7. CJS bypass, 80% collection 99.9 7.2 116.1 11.7 688.5 at SFD, 80% collection at BRD4,5 8. Bypass through all projects 99.9 7.2 116.1 11.7 688.5 (C.J. Strike to HCC), 100% bypass at BRD4,5 9. 80% collection at CJS, 99.9 7.2 116.1 11.7 688.5 bypass at all projects (Swan Falls to HCC), 100% bypass at BRD4,5

1 Upstream costs based on fish ladders. Trap-and-transport options would cost less than fish ladders (see Chapter 9, Aurdahl et al. 2001). 2 Scenario 1 was conducted to establish a baseline for downstream survival estimates under assumed free-flowing conditions for comparisons to in-reservoir and transport options. No passage costs estimated. 3 Cost of facilities in Scenario 2 included in all scenarios. 4 Cost of facilities at Swan Falls and C.J. Strike projects assumed to be comparable to Oxbow Project estimates from Chapter 9 (Aurdahl et al. 2001). 5 Downstream cost of Brownlee Project assumes both forebay collection and behavioral guidance structure as discussed in Chapter 9 (Aurdahl et al. 2001). 6 Total cost assumes one-time construction cost and 25 years of annual O&M at the presented annual rate. (See Chapter 9 (Aurdahl et al. 2001) for assumptions relating to cost estimates.)

Hells Canyon Complex Page 53 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

1

0.9 A B C 0.8 D A B E 0.7 C D F G S. Chinook 0.6 Steelhead E F. Chinook Survival 0.5 F G

0.4 H I 0.3 J 0.2 400 500 600 700 800 900 1000 River Kilometers

A - Pine Creek B - Wildhorse River C - Powder River D - Weiser River E - Bruneau River F - Salmon Falls Creek G - Rock Creek H - Walters Ferry - Snake River I - Below C.J. Strike Dam - Snake River J - Above C.J. Strike Reservoir - Snake River

Figure 1. Survival of spring chinook, steelhead, and fall chinook smolts from river kilometers of the Snake River where mainstem smolt outmigration would begin to the tailrace of Lower Granite Dam under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir.

Page 54 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

2.5 Spring Chinook 2 A B C D 1.5 LSAR / HRE E LSAR / LRE F G HSAR / HRE 1 HSAR / LRE

0.5

0 400 500 600 700 800 900 1000 2.5 Steelhead

2

1.5 LSAR / HRE LSAR / LRE A B HSAR / HRE 1 C D HSAR / LRE E F G 0.5

0 Proportion of Required Escapement 400 500 600 700 800 900 1000

2.5 Fall Chinook 2

1.5 LSAR / HRE LSAR / LRE HSAR / HRE 1 H HSAR / LRE I J 0.5

0 400 500 600 700 800 900 1000 River Kilometers

Figure 2. The relationship between location (river kilometer) of production areas and the proportion of adult returns to Hells Canyon Dam to required adult escapement under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir, under low and high smolt-to-adult returns (LSAR and HSAR), and under low and high assumptions of required escapement (LRE and HRE). Letters above refer to the following subbasins and locations along the mainstem Snake River: A = Pine Creek, B = Wildhorse River, C = Powder River, D = Weiser River, E = Bruneau River, F = Salmon Falls Creek, G = Rock Creek, H = Walters Ferry, I = Below C.J. Strike Dam, J = Above C.J. Strike Dam.

Hells Canyon Complex Page 55 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

2000 Spring Chinook

1500 LSAR

HSAR 1000 LRE

HRE 500

0 1 3a 4 5b 6b 7b 8b 9b 2 3b 5a 6a 7a 8a 9a 2000 Steelhead Number of Adults

1500 LSAR

HSAR 1000 LRE

HRE 500

0 1 3a 4 5b 6b 7b 8b 9b 2 3b 5a 6a 7a 8a 9a Reintroduction Scenario

Figure 3. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from Pine Creek under low and high assumptions for required escapement (LRE and HRE, horizontal lines) for each reintroduction scenario.

Page 56 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

2000 Spring Chinook

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 2000 Steelhead Number of Adults Number of

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b Reintroduction Scenario

Figure 4. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Wildhorse River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario.

Hells Canyon Complex Page 57 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

2000 Spring Chinook

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 2000 Steelhead Number ofNumber Adults

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b Reintroduction Scenario

Figure 5. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of number of adults required to maintain smolt production from the Powder River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario.

Page 58 Hells Canyon Complex Idaho Power Company Chapter 11: Reintroduction Alternatives

2000 Spring Chinook

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 2000 Steelhead Number of Adults

1500 LSAR HSAR

LRE 1000 HRE

LRE_T

500 HRE_T

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b

Reintroduction Scenario

Figure 6. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of number of adults required to maintain smolt production from the Weiser River under low and high estimates for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario.

Hells Canyon Complex Page 59 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

30 Fall Chinook A 25 LSAR

20 HSAR LRE 15 HRE Thousands 10 LRE_T HRE_T 5

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 12

B s

t 10

l LSAR u

d 8 HSAR A

LRE f 6

o HRE

r Thousands

e 4 LRE_T b HRE_T

m 2

u N 0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 30 C 25 LSAR

20 HSAR LRE 15 HRE Thousands 10 LRE_T HRE_T 5

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b Reintroduction Scenario

Figure 7. Estimated adult returns of fall chinook to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Walters Ferry Reach (A), above Swan Falls Reach (B), and above C.J. Strike Reach (C) of the Snake River under low and high assumptions for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario.

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12 Spring Chinook

10 LSAR

8 HSAR

LRE 6 HRE

Thousands LRE_T 4 HRE_T

2

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b 12 Steelhead

Number of Adults 10 LSAR

8 HSAR

LRE 6 HRE

Thousands LRE_T 4 HRE_T

2

0 1 2 3a3b4 5a5b6a6b7a7b8a8b9a9b

Reintroduction Scenario

Figure 8. Estimated adult returns of spring chinook (top) and steelhead (bottom) to Hells Canyon Dam (symbols) under low and high smolt-to-adult returns (LSAR and HSAR) compared with estimates of the number of adults required to maintain smolt production from the Bruneau River under low and high assumptions for required escapement (LRE and HRE, horizontal lines) with transportation (T) and without adult transportation for each reintroduction scenario.

Hells Canyon Complex Page 61 Feasibility of Reintroduction of Anadromous Fish Idaho Power Company

2.5 Spring Chinook A B C 2 D

E 1.5 F G

1

Proportion of Required Escapement 0.5

0 400 500 600 700 800 900 1000 River Kilometer

LSAR / HRE HSAR / HRE LSAR smolts/spawner LSAR / LRE HSAR / LRE HSAR smolts/spawner A - Pine Creek B - Wildhorse River C - Powder River D - Weiser River E - Bruneau River F - Salmon Falls Creek G - Rock Creek

Figure 9. The relationship between location (river kilometer) of production areas and the proportion of adult returns at Lower Granite Dam to required adult escapement for spring chinook under assumed free-flowing conditions in the Snake River above Lower Granite Reservoir, under assumptions using combinations of low and high smolt-to-adult returns (LSAR and HSAR) and low and high estimates of required escapement (LRE and HRE), and smolts per spawner estimates under LSAR and HSAR conditions using Petrosky et al. (2001).

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