(E.3.1-3) (Chapter 1) the Timing and Distribution of Fall Chinook Salmon Spawning Downstream of the Hells Canyon Complex

Evaluation of Anadromous Fish Potential Within the Mainstem Snake River, Downstream of the Hells Canyon Complex of Reservoirs

Phil Groves Editor

The Timing and Distribution of Fall Chinook Salmon Spawning Downstream of the Hells Canyon Complex

Phillip A. Groves Anadromous Fisheries Biologist

Technical Report Appendix E.3.1-3 Evaluation of Anadromous Fish Potential Within the Mainstem Snake River, Downstream of the Hells Canyon Complex of Reservoirs

Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

TABLE OF CONTENTS

Table of Contents...... i

List of Tables ...... iii

List of Figures...... iii

Abstract...... 1

1. Introduction...... 2

2. Study Area ...... 3

3. Methods...... 4

4. Results...... 5

1991...... 5

1992...... 6

1993...... 6

1994...... 7

1995...... 7

1996...... 7

1997...... 8

1998...... 8

1999...... 9

2000...... 9

5. Discussion...... 9

5.1. Temperature and Spawn Timing...... 10

5.2. Thermal Alterations at the HCC ...... 11

5.3. Flow Levels and Spawn Distribution...... 13

6. Summary and Conclusions ...... 15

Hells Canyon Complex Page i Evaluation of Anadromous Fish Potential Idaho Power Company

7. Acknowledgments...... 17

8. Literature Cited ...... 17

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Figure 2. Cumulative percent completion of spawning within the Snake River, by Julian week, 1991–2000. Data used for this graph is based on surveys conducted at the beginning of each Julian week...... 35

Figure 3. A comparison of cumulative percent completion of spawning for 1991, 1992, 1998, 1999, and 2000...... 36

Figure 4. A comparison of water temperatures recorded within the main Snake River near Swan Falls Dam (RKM 737), the head of Brownlee Reservoir (RKM 556), and downstream of the Hells Canyon Dam near Pittsburg Landing (RKM 348), May 1996–January 1999...... 37

Figure 5. The relationship of number of adult fall chinook salmon allowed to escape past Lower Granite Dam, comprising the Snake River spawning population, and the corresponding observed number of spawning sites being used, 1991–2000...... 38

Page iv Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

ABSTRACT

Prior to 1991, very little was known about the timing and distribution of fall chinook salmon spawning within the Snake River. Such knowledge was crucial for Idaho Power Company (IPC) to implement a provisional flow program designed to benefit threatened fall chinook salmon. Therefore, in 1991, IPC joined with the Washington Department of Fisheries and Wildlife, U.S. Fish and Wildlife Service, U.S. Forest Service, and the Nez Perce Tribe in a cooperative effort to enhance spawning surveys within the Snake River Basin. Our main objectives were to identify the timing and distribution of spawning throughout the Snake River between Asotin, Washington, and the Hells Canyon Dam. Spawning surveys were conducted along the 165-km-long, free-flowing reach of the Snake River between Asotin and the Hells Canyon Dam generally from mid-October through mid-December, 1991 through 2000. Turbidity in our study area was generally low, permitting visual aerial and underwater video surveys to identify and enumerate fall chinook redds. Surveys conducted through the 1990s showed that spawning typically begins by mid-October, peaks by early November, and is essentially completed by late November. The number of fall chinook redds observed within the mainstem Snake River (shallow and deep-water inclusive) has increased over recent years from a low of 46 in 1991 to a high of 373 in 1999. Redd construction at water depths greater than 3.0 m (unsurveyed previous to 1991) can account for as much as 50% of the spawning activity within the mainstem Snake River but more commonly comprises about 30%. Spawning (both shallow and deep) has been observed throughout the free-flowing reach of the Snake River from about river kilometer (RKM) 239 to RKM 397, at 85 and 29 documented shallow and deep-water spawning locations, respectively. While the absolute number of specific locations used for spawning has tended to increase as escapement numbers have increased, during the highest level of use (1999–373 redds) only 35% of shallow and 38% of deep-water sites were used to the maximum ever documented. This evidence suggests that full seeding, or carrying capacity in terms of spawning, has not been attained at even the highest escapement levels. Fall chinook within the Snake River spawn during the descending limb of the thermal regime of the river, generally beginning as water temperatures reach 16.0 °C and ending as temperatures drop to 7.0 °C. However, we have observed that the initiation of spawning can begin when temperatures are as high as 17.0 °C or can be delayed until temperatures are as low as 12.0 °C, making it impossible to predict or manipulate when the initiation of spawning will occur relative to water temperature. Though water temperature influences spawn timing, we also suspect that because fall chinook salmon are gregarious, spawn timing may be more dependent on the total number of fish within the population and how clumped their distribution is upon arrival upstream of Lower Granite Dam. The results from this study suggest that fall chinook salmon within the mainstem Snake River follow a life history pattern of spawn timing that is no different from that of other local populations, within thermal bounds that are described as normal for this stock. Therefore, these fish should not be experiencing increased risks to stress or mortality.

Hells Canyon Complex Page 1 Evaluation of Anadromous Fish Potential Idaho Power Company

1. INTRODUCTION

Historically, fall chinook salmon (Oncorhynchus tshawytscha) spawned throughout the Snake River from its confluence with the Columbia River upstream to about Shoshone Falls (Gilbert and Evermann 1892; Fulton 1968; Armour 1990). During the twentieth century, construction of hydroelectric projects blocked access to and inundated habitat in both the upper and lower river (Irving and Bjornn 1981, Dauble et al. 1999). By 1975, fall chinook spawning habitat was primarily limited to the free-flowing portion of the Snake River located between Asotin, Washington, near river kilometer (RKM) 233.4, and the Hells Canyon Dam (HCD), upstream at RKM 398.6. Additional, less predominant spawning continued to occur within the Clearwater, Grande Ronde, Imnaha, Tucannon, and Salmon rivers (major tributaries to the Snake River), as well as in tailraces of the lower Snake River dams (Irving and Bjornn 1981; Mendel et al. 1992; Connor et al. 1993; Garcia et al. 1994a,b; Mendel et al. 1994; Garcia et al. 1996; Groves and Chandler 1996; Garcia et al. 1997; Dauble et al. 1999; Garcia et al. 1999; Garcia et al. 2000; Garcia et al. 2001a). Throughout the twentieth century, fall chinook salmon declined in abundance. In 1992, this stock was finally listed as threatened by the National Marine Fisheries Service (NMFS) under the Endangered Species Act (ESA) (NMFS 1992).

In 1991, to help preserve the fall chinook salmon, Idaho Power Company (IPC) voluntarily adopted a flow program designed to provide stable habitat for spawning fall chinook salmon in the Snake River downstream of the HCD (IPC 1990). This flow program primarily consists of maintaining a steady, stable flow from the HCD during the spawning season and then adopting that flow as a minimum discharge throughout the incubation period until fry emergence is essentially complete. In 1991, however, very little was known about the timing and distribution of spawning within the Snake River, yet such knowledge was crucial for IPC to adequately implement the provisional flow program. A review of historical data revealed that past spawning surveys were not conducted yearly, and seldom was more than one survey conducted during any one year (Welsh et al. 1965, IPC memo 1978, WDFW memo 1987, WDFW memo 1988, WDFW memo 1990, WDFW memo 1991). These data also did not indicate whether the entire river was searched during historical surveys or observations were limited to specific river segments or known spawning locations. Although the prevailing thought was that spawn timing downstream of the HCD was limited to November and early December, with the bulk of spawning occurring in late November, the historical survey data clearly could not support that conclusion.

In 1991, IPC joined with the Washington Department of Fisheries and Wildlife (WDFW), U.S. Fish and Wildlife Service (USFWS), U.S. Forest Service (USFS), and the Nez Perce Tribe (NPT) in a cooperative effort to enhance spawning surveys within the Snake River Basin. Our main objectives were to identify the timing and distribution of spawning throughout the Snake River between Asotin, Washington, and the HCD. Secondary objectives included analyzing trends for spawner:redd ratios, identifying the relative use of major tributaries, locating individual redds to collect habitat-use information, and identifying specific spawning areas where biologists could model the relationship between discharge and spawning habitat quantity. Results from the secondary objectives will be presented in separate reports.

Page 2 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

2. STUDY AREA

For this report, surveys were conducted along the 165-km-long, free-flowing reach of the Snake River between Asotin and the HCD. This river reach flows north from the HCD and is bounded on the east by Idaho, and on the west by Oregon and Washington. Within this study area, three distinct segments were identified based on the river’s physical characteristics, such as gradient, discharge, temperature, channel width, and turbidity.

The upper segment, approximately 95 km long, runs from the HCD downstream to the confluence of the Salmon River (RKM 303.0). This segment has a narrow channel with an average river gradient of 0.2%, short and deep pools, and numerous rapids of high and low gradient. Since 1991, flows during the spawning season (from about mid-October through mid- December) have been held steady. In accordance with the IPC interim protective flow plan, the spawning flow is established as the minimum discharge until fry emergence is estimated to be complete (usually by early May to early June of the following year). As a result of these flows, the turbidity within the upper segment remains relatively low and constant, generally less than 2.0 nephelometric turbidity units (ntu) from late October through early December.

The middle segment, approximately 32 km long, runs north from RKM 303.0 to the confluence of the Grande Ronde River (RKM 271.5). This segment could be termed a transitional zone, as the average river gradient is 0.2% within the upper third, but then abruptly drops to about 0.07% as the narrow and steep-banked channel widens near RKM 289.7. During the fall spawning period, the daily mean flow is slightly higher, but relatively stable, due to influences from the Salmon River. Turbidity within the middle segment, also influenced by the Salmon River, is usually more variable, with observed extremes during our surveys of between 1.0 and 11.0 ntu.

The lower segment stretches approximately 38 km downstream from the Grande Ronde River confluence. Throughout this segment, the river gradient remains low, around 0.07%, and the river channel remains wide, with gently sloping shorelines. This lower segment can also be characterized as having long, deep pools and runs and low-gradient rapids. Because of compounded influence from the Salmon and Grande Ronde rivers, the discharge and turbidity within this segment during the fall spawning period is higher and more variable than in the upper segments. During the spawning period, observed turbidity has ranged between 0.7 and 13.2 ntu.

In the fall (October through December), the water temperature within the upper segment tends to be slightly warmer than in the middle and lower segments. By about mid-January through early March, the temperature throughout the entire reach (from the HCD downstream to Asotin) is virtually the same. Finally, in early spring (March through mid-June), the water temperature in the upper segment is slightly cooler than in the middle and lower segments. This thermal disjunction results from a combination of reservoir buffering at Brownlee and the quantity of water provided from the Salmon River.

Hells Canyon Complex Page 3 Evaluation of Anadromous Fish Potential Idaho Power Company

3. METHODS

The primary data for this report were collected during the fall spawning periods of 1991 through 2000. Supplemental data from surveys conducted prior to 1991 will be used for comparisons. Also, in order to provide a comprehensive base of data, survey results from the Clearwater, Grande Ronde, Salmon, and Imnaha rivers will be provided. With turbidity in our study area generally low, conditions permitted visual aerial and underwater video surveys to identify and enumerate fall chinook redds. We classified redds detected during aerial surveys as shallow (generally at depths ≤ 3.0 m) and those located by underwater video searches as deep (depths > 3.0 m). Video surveys upstream of Lower Granite Dam tailwaters have only been conducted within the mainstem Snake River.

Aerial surveys occurred approximately once per week (7-day interval) during the spawning period, generally from mid-October through mid-December. During the 10 years of surveys, this periodicity was compromised only a few times due to poor weather conditions or mechanical difficulties. Flights began near the town of Asotin and covered the entire length of the free-flowing reach of the Snake River upstream to the HCD. From 1991 through 1998, observations were made using a three-seat helicopter (center pilot and two outboard observers) operated at an altitude of approximately 200 m above the water surface and at a cruising speed of approximately 70 km/h (Mendel et al. 1992, Connor et al. 1993, Groves and Chandler 1996). In 1999 and 2000, a Bell Jet Ranger was used for aerial surveys. This type of helicopter provides for both a forward seated pilot and main observer, with a “back-seat” secondary observer (Garcia et al. 2001a). Spawning locations and weekly numbers of new redds were noted on a U.S. Army Corps of Engineers navigation chart of the Snake River.

Because redds of fall chinook salmon had been reported at depths of about 10.0 m in the Columbia River (Chapman 1943, Chapman et al. 1986, Swan 1989) and aerial observations within our study area normally detect redds to depths of about 3.0 m, we expanded our aerial surveys with remote underwater video searches of potential deep-water spawning areas. Turbidity within the free-flowing reach of the Snake River can be relatively low (< 4.0 ntu), providing good to excellent conditions for underwater videography (Groves 1993, Groves and Garcia 1998, Groves and Chandler 1999). During summer 1992, we identified substrate patches of gravel/cobble (2.5–15.0 cm, long axis length) by using remote underwater videography in areas that would be deeper than 3.0 m when discharge was near the sustained fall spawning flows. We inspected all pool tail-out areas, deeper zones contiguous with known spawning locations, and deep runs exhibiting laminar flow patterns. Throughout the three segments of the Snake River, we identified 89 sites that contained potential spawning substrate at depths greater than 3.0 m (Groves and Chandler 1999).

Our video system consisted of a miniature, remote, submersible camera attached to a hydraulic weight, connected to a video camcorder and monitor (Groves and Garcia 1998). A manually operated, depth-calibrated winch controlled the positioning of the camera. To reduce disturbance to spawning adults, video searches were initiated in mid-November as spawning activity began to decline. Each year, after determining how many sites could be searched given manpower availability and time constraints during the spawning season, we randomly selected

Page 4 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution sites from the 89 identified deep-water areas. Biologists from IPC and the USFWS then cooperatively searched the chosen sites.

Typical deep-water searches consisted of a succession of either cross-channel transects viewed upstream (in a zigzag pattern) through the extent of a site (1993–1998) (Groves and Chandler 1999) or parallel transects oriented and viewed in a downstream-to-upstream manner (1999 and 2000). We maintained distance between transects at approximately 10.0 m by visually orienting to natural shoreline landmarks during surveys in 1993 through 1998 and by global positioning system (GPS) and geographic information system (GIS) software during 1999 and 2000. When redds were detected, the distance between transects was immediately reduced to 5.0 m in order to increase the chance of encountering redds. Each transect was considered complete if depth decreased to less than 3.0 m or increased to greater than 11.0 m (the limit of our visibility due to low light) or if the substrate no longer met the defined criteria (size range 2.5–15.0 cm, long axis length). The search patterns were monitored, and from 1994 through 1998 we recorded individual redd locations using a shore-based surveying instrument. These data were then entered into a GIS. Beginning in 1999, we delineated transects and recorded redd locations using real-time corrected GPS data viewed through an onboard GIS.

We obtained discharge data for the three relevant Snake River segments from U.S. Geological Survey (USGS) gauging stations. For the upper segment of the Snake River, discharge records were obtained from USGS gauge 13290450 (Table 1). For the middle segment, discharge information was calculated by adding the mean daily discharge for the upper segment of the Snake River with the mean daily discharge data reported from USGS gauge 13317000 for the Salmon River at White Bird (Table 1). For the lower segment of the Snake River, discharge data was obtained from records of the Anatone gauge, USGS station 13334300 (Table 1).

4. RESULTS

1991

In 1991, we conducted 9 survey flights, beginning 14 October and ending 9 December (Table 2). During these aerial surveys, 41 redds were observed at 9 distinct spawning locations within the Snake River (Figures 1a, 1b, and 1c; Table 3). The first redds were observed during the survey flight of 28 October. Spawning was estimated to be 50% complete by 14 November, 95% complete by 29 November, and 100% complete by the survey of 9 December (Figure 2). The only attempt during 1991 to assess potential deep-water spawning occurred at RKM 261.5. Scuba divers from the USFWS and IPC, using methods developed by Swan (1989), discovered a minimum of 5 additional redds while surveying potential deep-water spawning gravels adjacent to known shallow-water spawning at that site (Connor et al. 1993). For 1991 the final redd count within the Snake River was 46. Surveys within the major tributaries identified 4 redds in the Clearwater River, 0 redds in the Grande Ronde River, and 4 redds in the Imnaha River (Table 4).

Approximately 63% of the total redds observed within the Snake River in 1991 were located at 4 sites within the lower segment of the river, and 37% were observed at 5 locations

Hells Canyon Complex Page 5 Evaluation of Anadromous Fish Potential Idaho Power Company within the upper segment. No redds were observed within the middle segment. The largest concentration of redds (20) occurred at RKM 261.5. 1992

During 1992, we conducted 8 survey flights, beginning on 16 October and ending on 12 December (Table 2). During these aerial surveys, we observed 45 redds at 12 distinct locations in the Snake River (Figures 1a, 1b, and 1c; Table 3). At one of those sites, IPC crews discovered 1 additional redd during ground-truthing operations after the aerial redd surveys were completed. The first redds were observed during the survey flight of 5 November. Spawning was estimated to be 50% complete by 14 November, 95% complete by 30 November, and 100% complete by 12 December (Figure 2). During 1992 IPC and USFWS evaluated replacing scuba divers with remote underwater video equipment to assess spawning in deeper water. Combination video and scuba surveys were completed at 3 specific locations, and it was determined that video surveys provided essentially the same information as scuba divers but were less time consuming, required less manpower and equipment, and presented virtually no safety hazards to the crew (Garcia et al. 1994a). During this evaluation only 1 additional redd was discovered in habitat too deep for aerial observers to detect. For 1992, the final redd count within the Snake River was 47. Concurrent surveys of the major tributaries identified 26 redds in the Clearwater River, 5 redds in the Grande Ronde River, 1 redd in the Salmon River, and 3 redds in the Imnaha River (Table 4).

Approximately 66% of the total redds observed in the Snake River during 1992 were located at 5 sites within the lower segment, and 34% were observed at 7 locations within the upper segment. No redds were observed within the middle segment of the Snake River. The largest concentration of redds (11) occurred at RKM 261.5. 1993

Eight survey flights were conducted in 1993, beginning on 25 October and ending on 13 December (Table 2). A total of 60 redds were observed during the aerial surveys of the Snake River at 17 distinct spawning locations (Figures 1a, 1b, and 1c; Table 3). The first redds were observed during the survey flight of 25 October. Spawning was estimated to be 50% complete by 6 November, 95% complete by 28 November, and 100% complete by 13 December (Figure 2). In 1993 we increased video surveys of deep-water habitat and discontinued the use of scuba divers. IPC was able to complete video searches at 50 sites, and 67 additional redds were detected at 7 distinct locations, bringing the final Snake River redd count to 127. Tributary surveys identified an additional 36 redds in the Clearwater River, 49 redds in the Grande Ronde River, 3 redds in the Salmon River, and 4 redds in the Imnaha River (Table 4).

Within the Snake River, approximately 76% of the total redds observed in 1993 were located at 10 sites within the lower segment of the river, 9% at 2 sites within the middle segment, and 15% at 10 sites within the upper segment. The largest concentration of redds (37) was located at RKM 266.8.

Page 6 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

1994

We conducted 8 survey flights during 1994, beginning on 24 October and ending on 12 December (Table 2). During these aerial spawning surveys, we observed 51 redds at 20 distinct locations within the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial redd construction was observed during the flight of 24 October. Spawning was estimated to be 50% complete by 8 November, 95% complete by 28 November, and 100% complete by 5 December (Figure 2). In 1994, IPC and USFWS cooperatively searched 73 deep-water sites and detected an additional 16 redds at 4 distinct locations. The final 1994 redd count for the Snake River was 67. During tributary surveys, biologists identified 37 redds in the Clearwater River, 15 redds in the Grande Ronde River, 1 redd in the Salmon River, and 0 redds in the Imnaha River (Table 4).

Approximately 14% of the total redds observed in the Snake River during 1994 were located at 3 sites within the lower segment, 31% at 4 sites within the middle segment, and 55% at 14 sites within the upper segment of the river. The largest concentration of redds (13) was located at RKM 289.0. 1995

In 1995, we conducted 7 survey flights, beginning on 23 October and ending on 5 December (Table 2). During these aerial surveys, we observed 41 redds at 23 distinct spawning locations in the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial redd construction was observed during the survey flight of 23 October. Spawning was estimated to be 50% complete by 2 November, 95% complete by 17 November, and 100% complete by 27 November (Figure 2). IPC and USFWS cooperatively searched 42 deep-water sites and detected 30 additional redds at 3 distinct locations. The final 1995 redd count for the Snake River was 71. During tributary surveys, biologists identified 20 redds in the Clearwater River, 18 redds in the Grande Ronde River, 2 redds in the Salmon River, and 4 redds in the Imnaha River (Table 4).

Of the redds identified within the Snake River during 1995, approximately 9% were located at 2 sites within the lower segment of the river, 45% at 4 sites within the middle segment, and 46% at 18 sites within the upper segment. The largest concentration of redds (27) was located at RKM 289.0. 1996

We attempted seven survey flights during 1996, beginning on 21 October and ending on 2 December (Table 2). High turbidity within the lower segment of the Snake River during the 25 November survey flight limited observations to the middle and upper segments. These high turbidities originated from the Salmon and Grande Ronde rivers, and they effectively limited observations within those tributaries. We observed 71 redds at 22 distinct spawning locations during the aerial surveys of the Snake River (Figures 1a, 1b, and 1c; Table 3). Spawning was initially observed during the survey flight of 21 October. Spawning was estimated to be 50% complete by 30 October, 95% complete by 9 November, and 100% complete by 2 December (Figure 2). IPC and USFWS cooperatively searched 32 deep-water sites and detected 42 additional redds at 4 locations. In 1996, the final redd count for the Snake River was 113.

Hells Canyon Complex Page 7 Evaluation of Anadromous Fish Potential Idaho Power Company

Concurrent surveys of the major tributaries identified 69 redds in the Clearwater River, 20 redds in the Grande Ronde River, 1 redd in the Salmon River, and 3 redds in the Imnaha River (Table 4).

Approximately 10% of the total redds observed in the Snake River during 1996 were located at 4 sites within the lower segment, 40% at 3 sites within the middle segment, and 50% at 18 sites within the upper segment. The largest concentration of redds (41) was observed at RKM 289.0. 1997

We conducted 8 survey flights during 1997, beginning on 20 October and ending on 8 December (Table 2). During these aerial surveys, we observed 49 redds at 15 distinct spawning locations within the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial spawning was observed during the 20 October survey flight. Spawning was estimated to be 50% complete by 3 November, 95% complete by 16 November, and 100% complete by 1 December (Figure 2). IPC and USFWS cooperatively searched 63 deep-water sites, detecting an additional 9 redds at 2 sites. The final 1997 redd count for the Snake River was 58. The number of redds observed within the tributaries amounted to 72 within the Clearwater River, 55 in the Grande Ronde River, 1 in the Salmon River, and 3 in the Imnaha River (Table 4).

Within the Snake River, approximately 49% of the redds observed in 1997 were located at 5 sites within the lower segment, 9% at one site within the middle segment, and 42% at 10 sites within the upper segment. The largest concentration of redds (12) was located at RKM 245.1. 1998

In 1998, we conducted 8 survey flights, beginning on 19 October and ending on 7 December (Table 2). During these aerial surveys, we observed 135 redds at 33 separate spawning locations within the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial spawning was observed during the survey flight of 26 October. Spawning was estimated to be 50% complete by 1 November, 95% complete by 21 November, and 100% complete by 30 November (Figure 2). IPC and USFWS cooperatively searched 59 deep-water sites and detected an additional 50 redds at 5 sites. In 1998, the final redd count for the Snake River was 185. The number of redds observed within the tributaries was 78 in the Clearwater River, 24 in the Grande Ronde River, 3 in the Salmon River, and 13 in the Imnaha River (Table 4).

Within the Snake River, approximately 14% of the total redds observed in 1998 were located at 7 sites within the lower segment, 12% at 3 sites within the middle segment, and 74% at 28 sites within the upper segment. The largest concentration of redds (17) was located at RKM 341.5.

Page 8 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

1999

Nine aerial spawning surveys were flown in 1999, beginning on 11 October and ending on 7 December (Table 2). We observed a total of 273 redds at 54 distinct spawning locations within the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial spawning was observed during the survey flight of 18 October. Spawning was estimated to be 50% complete by 2 November, 95% complete by 14 November, and 100% complete by 7 December (Figure 2). IPC and USFWS cooperatively searched 73 deep-water sites and detected an additional 100 redds at 18 separate spawning locations. In 1999, the final redd count for the Snake River was 373. Tributary survey results totaled 184 redds in the Clearwater River, 13 redds in the Grande Ronde River, 0 redds in the Salmon River, and 9 redds in the Imnaha River (Table 4).

Approximately 8% of the total redds observed in the Snake River during 1999 were located at 6 sites within the lower segment, 14% at 6 sites within the middle segment, and 78% at 52 sites within the upper segment. The largest concentration of redds (40) was located at RKM 289.0. 2000

We conducted 9 survey flights during 2000, beginning on 9 October and ending on 4 December (Table 2). During these aerial surveys, we observed 255 redds at 50 separate spawning locations in the Snake River (Figures 1a, 1b, and 1c; Table 3). Initial redd construction was noted during the survey flight of 9 October. Spawning was estimated to be 50% complete by 2 November, 95% complete by 15 November, and 100% complete by 28 November (Figure 2). IPC and USFWS cooperatively searched 60 deep-water areas and detected an additional 91 redds at 8 sites. In 2000, the final redd count for the Snake River was 346. Tributary survey results totaled 172 redds in the Clearwater River, 8 redds in the Grande Ronde River, 0 redds in the Salmon River, and 9 redds in the Imnaha River (Table 4).

Within the Snake River, approximately 12% of the total redds observed in 2000 were located at 7 sites within the lower segment, 22% at 8 sites within the middle segment, and 66% at 39 sites within the upper segment. The largest concentration of redds (56) was located at RKM 289.0.

5. DISCUSSION

Prior to the initiation of this study, little was known about the timing and distribution of spawning by fall chinook salmon within the Snake River downstream of the HCD. The earliest aerial surveys took place only once per season, and few records indicate when during the season these surveys were conducted (Table 5). In the late 1980s, even when the number of aerial surveys increased to two per season, the resulting data still did little to help biologists fully understand the timing and distribution of spawning by these fish within the Snake River. Results from those early surveys merely indicated that spawning did occur downstream of the HCD. Both the increased periodicity of aerial surveys beginning in 1991 and the advent of aggressive

Hells Canyon Complex Page 9 Evaluation of Anadromous Fish Potential Idaho Power Company deep-water video searches since 1993 have increased our knowledge of where and when fall chinook salmon spawn within the Snake River downstream of the HCD. 5.1. Temperature and Spawn Timing

Historically, knowledge of spawning times for fall chinook salmon within the Snake River has been based on conjecture, especially for the reach between HCD and Asotin. This conjecture, founded on an almost nonexistent base of data, has persisted even to the present. By 1990 it was assumed that within our study reach fall chinook salmon began spawning by early November, peaked near the end of November, and ended around mid-December. Data collected during the 1991 through 1994 surveys seemed to corroborate this assumption (see Figure 3) and perpetuated the paradigm that within the Snake River downstream of the HCD fall chinook spawning occurred late in the season, especially when compared to spawn timing of fall chinook within the Hanford Reach of the Columbia River. Additionally, the 1991 and 1992 data seemed to indicate that spawning initiation was controlled in large part by water temperature. However, as surveys continued through the late 1990s, it became apparent that spawning more often begins by mid-October, peaks by late October or early November, and is completed from mid- to late November, especially as evidenced by survey results from 1995 through 2000 (see Figure 3). This pattern of spawn timing is similar to what has been observed and reported for fall chinook spawning within the Hanford Reach of the Columbia River (Dauble and Watson 1997; Dell and Kindley 1985; Dell and Carlson 1987, 1988a, 1988b; Carlson and Dell 1990, 1992).

Data from the last 10 years of surveys also indicate that initiation of spawn timing is dynamic and complex—and impossible to predict on the basis of water temperature. Data presented for the Hanford Reach of the Columbia River show a similar lack of predictability (Dauble and Watson 1997). Certainly temperature is important, but we suspect that because fall chinook salmon are gregarious, spawn timing is also determined by the total number of fish within the population and how clumped their distribution is upon arrival upstream of Lower Granite Dam. Data from the 1991 and 2000 surveys, along with corresponding water temperatures from our study area and passage information from Lower Granite Dam, can be used to illustrate these theories. In 1991, spawning started just prior to the survey flight of 28 October (between weeks 43 and 44). The daily mean water temperature, as measured at the thermograph nearest to where spawning began in 1991, had dropped from 14.5 to 12.2 °C during the week preceding the 28 October survey flight. By the date of this survey flight, the percentage of the total run that had passed Lower Granite Dam was 96%, but the total number of adults counted at Lower Granite Dam was only 604. In contrast, spawning in 2000 began just prior to the survey flight of 9 October (between weeks 41 and 42), two weeks earlier than in 1991. The daily mean water temperature, as measured at the thermograph closest to where spawning began in 2000, had dropped from 17.8 to 17.0 °C during the week preceding the 9 October survey flight. By that survey flight, 87% of the total run had passed Lower Granite Dam (a lower percentage than seen in 1991); however, the total number of fish counted by that date was 3,188. This is five times the number observed in 1991, thus providing a higher density of fish within the reach. It should also be noted that spawning during 1995 through 2000 was virtually complete 1 to 2 weeks earlier than in 1991 through 1994. Recent radiotelemetry data collected by the USFWS also indicated

Page 10 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution that adult fall chinook salmon passing upstream from Lower Granite Dam do not appear to be congregating and holding in thermal refugia prior to spawning (Garcia et al. 2001b).

There has been serious debate recently about whether spawn timing of fall chinook salmon within the Snake River downstream of the HCD has been temporally altered in the post- dam construction period (since 1967) to the detriment of the stock, compared with what may have historically occurred. What little data exists from the Marsing Reach of the Snake River upstream of the Hells Canyon Complex (HCC) (pre-1960) has been used to support this theory. Unfortunately, no clear data describes historical spawn timing within the Marsing Reach, and no historical data exists for the river reach downstream of the HCD. It is likely that the two reaches historically had very different habitats. Chandler et al. (2001) present a thorough discussion on this topic. Sparse accounts from commercial fishing operations within the Marsing, Idaho, and Ontario, Oregon, areas and anecdotal information from Idaho Department of Fish and Game biologists suggest that spawning may have begun by early October and have been completed by mid-November (Evermann 1896, Van Dusen 1903, IDFG 1953, NMFS 2000). Based on this information, biologists have assumed that spawn timing of fall chinook salmon within the Snake River downstream of the HCD occurs approximately 2 weeks later now than historically and that this timing affects incubation and out-migration timing. Furthermore, it has been speculated that the existence and operations of the HCC have caused the assumed temporal shift in spawn timing. However, the survey data collected over the past 10 years indicate that present- day fall spawn timing downstream of the HCC is similar to the timing hypothesized for the historical population that spawned in the Marsing Reach of the Snake River. No evidence indicates that operations of the HCC have shifted, or continue to modify, spawn timing. More importantly, though, historic conditions in both the Marsing and Hells Canyon reaches were likely very different 50 to 60 years ago, prior to accelerated agricultural and urban development and the existence of the HCC. Because these two reaches had such contrasting thermal environments, we should be very careful about comparing them and assuming that what might have occurred in one is representative of what occurred in the other. 5.2. Thermal Alterations at the HCC

Limited historic and present-day information indicate that the HCC reservoirs (especially Brownlee) have actually created a more beneficial thermal habitat downstream of the complex than what may have been present before the complex existed (Chandler et al. 2001). Within the Marsing Reach of the Snake River, where fall chinook salmon spawned prior to the existence of the HCC, the thermal regime of the mainstem habitat was probably buffered by significant spring-flow recharge. The numerous springs that provided water to the Snake River upstream of that reach would have acted to moderate high summer and low winter water temperatures. This thermal buffering would have provided a unique environment beneficial to spawning, incubation, and early rearing of fall chinook salmon. In contrast, just upstream of the present headwaters and within the upper body of Brownlee Reservoir, a number of significant tributaries (including Pine Creek and the Boise, Payette, Weiser, Malheur, Burnt, Powder, and Wildhorse rivers) probably altered the historical thermal regime of the river downstream of the present HCC, at least as far downstream as the Salmon River confluence. These tributaries probably cooled the mainstem Snake River rapidly during the fall, faster than what occurred upstream, and depending on local climatic conditions, the tributaries could have caused the winter temperatures to be significantly

Hells Canyon Complex Page 11 Evaluation of Anadromous Fish Potential Idaho Power Company colder than what occurred in the historical Marsing Reach. Colder fall and winter water temperatures would slow the development of incubating embryos, thereby delaying emergence. In a similar fashion, the influence of those tributaries, and low mainstem flows, could have caused the summer temperature within the mainstem Snake River downstream of the present HCC to have warmed more rapidly and to reach a considerably higher maximum temperature earlier in the year. This effect, combined with delayed emergence, would result in a very short rearing period before out-migration of juveniles would occur. The thermal alteration that likely occurred between the Marsing Reach and the Hells Canyon Reach, as well as the thermal buffering of the lower river by the HCC, is illustrated with water temperature data from the Swan Falls Dam (at the upper end of the Marsing Reach), from RKM 556.2 just upstream of the Brownlee Reservoir Pool and from RKM 347.5 downstream of Hells Canyon Dam (Figure 4).

If we assume, for illustration purposes, that most spawning occurs as the river cools to 16.0 °C (Healey 1991), then spawning in the historical Marsing Reach would have occurred earlier than within either the pre-HCC or the present-day Hells Canyon Reach. Also, if we assume that as temperatures decrease below 7.0 °C, spawning is inhibited, then the length of the spawning period available to the fish in the present-day Hells Canyon Reach would be closer to what was available in the Marsing Reach (Chandler et al. 2001). Depending on the local climatic conditions during the fall and winter, water temperatures downstream of the pre-HCC reach may have dropped very close to freezing. This cooling would significantly affect incubating embryos, slowing their development and delaying emergence. Finally, if we assume that out-migration of juveniles reaches a maximum as water temperatures begin to approach 17.0 °C, then the amount of time available for post-emergent juveniles to rear and grow prior to smolting is greatest within the Marsing and present-day Hells Canyon reaches, while that time may have been considerably curtailed downstream of the pre-HCC reach.

The data in Figure 4 and the conclusions presented above probably do not illustrate the full potential of thermal alteration because some tributaries that would have affected conditions in the Hells Canyon Reach are downstream of RKM 556, and therefore their effects are presently diluted by Brownlee Reservoir. Also, many of the tributary systems themselves have been altered with impoundments that tend to moderate their influence on the mainstem Snake River. The thermal character of the pre-HCC Hells Canyon Reach was likely more extreme than the present data indicates (Figure 4) because of the potentially higher volumes of colder and warmer water provided during winter and summer by a larger number of unaltered tributaries. In the pre- HCC Hells Canyon Reach, the spawning window would have been shorter, the time required for incubation may have been longer, and the time available for rearing prior to out-migration would have been shorter. The Brownlee Reservoir appears to provide a thermal buffer that helps moderate low winter and high summer temperatures within the Hells Canyon Reach in a manner similar to (but not to the extent of) spring influences in the historical Marsing Reach. Without this reservoir buffering, the habitat and production capability downstream of the present HCC would be even more thermally constrained than is believed currently to be the case.

Concern has been expressed that water temperature downstream of the HCC could potentially affect early development and survival of embryos. Snake River water temperature data collected concurrently with spawning survey observations indicate that spawning within the upper section of the Snake River can begin when temperatures are declining from 17.0 °C but

Page 12 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution more commonly begins as temperatures drop from 16.0 to 15.0 °C (Tables 6a and 6b). These temperature observations are similar to those made for spring chinook salmon spawning within the Willamette River (Mattson 1948), for fall chinook salmon spawning within the Hanford Reach of the Columbia River (Dell and Kindley 1985; Dell and Carlson 1987, 1988a, 1988b; Carlson and Dell 1990, 1992), and generally for all chinook (Healey 1991). Laboratory studies have shown that embryos subjected to temperatures above 17.0 °C can suffer significant losses to immediate and delayed mortality (Donaldson 1955, Olson and Foster 1955, Coutant 1977, Murray and McPhail 1988). However, those studies usually maintained developing embryos at constant temperatures. Olson and Foster (1955) allowed experimental lots to mimic a seasonal temperature trend, comparing high and low experimental seasonal temperatures with a control lot maintained at a normative seasonal temperature regime. Results from their study indicated that embryos incubated at the highest temperatures (beginning near 18.0 °C, dropping to 5.5 °C, and then climbing to 11.0 °C) had the highest mortality, and that the mortality occurred mainly post- hatching. Lots maintained at all other experimental seasonal temperatures (both higher and lower than the control group) resulted in similar mortality when compared with the control lot. This experiment demonstrates that embryos incubated through a seasonal temperature regime between 16.0 and 1.0 °C will result in normal survival through emergence. Healey (1991) makes this same observation and states that while chinook salmon in natural systems may begin spawning at temperatures around 16.0 °C, very little mortality would be expected, as the seasonal thermal regime is usually dropping quickly. Within the mainstem Snake River, there have been only three years when redd construction began prior to when temperatures dropped below 16.0 °C (Tables 6a and 6b). However, the percentage of redds observed when temperatures have been above 16.0 °C has never been greater than 1.5%. As has been noted earlier, water temperatures are decreasing as the spawning period begins, and the potential threat to incubating embryos due to lethal temperatures is probably negligible. Also, though redd construction within the Hells Canyon Reach has been observed prior to when temperatures have dropped below 17.0 °C (1 redd of 346 during the 2000 spawning season), it is speculative, at best, to assume that eggs were indeed in the gravel. The actual deposition of eggs within that single redd may have occurred within the next 14 days, as temperatures dropped to 15.0 °C. 5.3. Flow Levels and Spawn Distribution

During the late 1980s and early 1990s, very little spawning habitat was assumed to exist within the Snake River downstream of the HCC. Redds were expected to be distributed among a few sites thought to be downstream of the Grande Ronde River confluence (where the largest amount of potential habitat presumably occurred). Indeed, spawning surveys during those years showed few specific sites being used, and most of the spawning observed during any year occurred at a single site. However, continued survey efforts have shown that spawning occurs throughout the entire free-flowing reach of the Snake River from just upstream of Asotin (at RKM 239.0) to just downstream of the HCC (RKM 395.6) (Figures 1a, 1b, and 1c).

Based on aerial surveys, 85 shallow-water spawning sites have been identified and documented within the Snake River between 1991 and 2000. The number of sites used per year appears to be positively correlated with the number of fish allowed to escape past Lower Granite Dam, making up the spawning population (Figure 5). While the number of sites being used continues to increase as the escapement increases, the relative use of individual sites has not

Hells Canyon Complex Page 13 Evaluation of Anadromous Fish Potential Idaho Power Company increased correspondingly. The average number of redds per site has remained near 5 but is highly variable and has ranged between 1 and 25 during any single year. Even at the highest level of use (1999—373 redds), only 35% of shallow and 38% of deep-water sites were used to the maximum ever documented. This evidence suggests that full seeding, or carrying capacity in terms of spawning, has not been attained at even the highest escapement levels. Also, the percentage of spawning within each of the 3 river sections has not remained constant. From 1991 through 1993, the majority of redds identified were located downstream of the Grande Ronde River, but since 1994, most observed redds have been upstream of the Salmon River. No single site has been used every year. Three sites (4%) have had the highest use, each being used 8 times in 10 years, and only 15 (18%) of the documented sites have been used at least 6 times during the last 10 years. At the most consistently used sites, the number of redds observed has been variable, and these most consistently used sites are not necessarily where the largest number of redds are constructed each year. There is also no correlation between the number of sites used during any given year and the respective base spawning discharge flow from Hells Canyon Dam. As a final note, 4 documented sites are within eddies where the fish orient into current but actually face “downriver” when spawning. Interestingly enough, these are not just “one-time use” sites.

Between 1993 and 2000, based on video surveys, an additional 29 deep-water spawning sites have been documented within the Snake River. As noted for shallow-water sites observed during aerial surveys, the number of sites used in any given year has generally increased as the escapement levels at Lower Granite Dam increase. The consistency of deep-water site use from year to year has also been variable. Only 3 (11%) of the deep-water sites have been used 4 times during the last 8 years when video searches were conducted. However, one site (RKM 289.0) has been used all 8 years. As with shallow-water sites, the number of redds observed at individual deep-water sites is highly variable, ranging between 1 and 48. Even at the most consistently used site, the quantity of redds has been variable from year to year; however, use at that site generally constitutes about 50% (range 3–83%) of the total deep-water spawning. While the increase in site use appears to be related to the number of adults in the spawning population, there is no corresponding relationship between site use and discharge from the HCD.

Three sites within the upper segment and one site within the middle segment have been designated as deep-water areas only when spawning discharges between 12,000 and 13,000 cfs have occurred from HCD. Flows of that level correspond to a depth of about 0.25 m greater than depths observed when the discharge is held near 9500 cfs. It should be understood that spawning occurs at these four sites within the exact same areas, even when discharges are held near 9500 cfs. Likewise, the number of redds present during the highest discharge (1999) has been similar to other years when flows were held near 9500 cfs. There appears to be no increase in either the amount or quality of the habitat provided at these sites under the varying discharges. These four sites, at flows of about 9500 cfs, are actually on the edge of visibility during aerial surveys because of their overall depth. As the discharge is increased to about 12,500 cfs, the ability to detect redds from the air decreases significantly; therefore, redds are only observed by using the remote video systems.

Page 14 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

6. SUMMARY AND CONCLUSIONS

Prior to 1991, virtually no available information described the spawn timing and distribution of use of the Hells Canyon Reach of the Snake River by fall chinook salmon. When NMFS was petitioned to place this fish stock on the endangered species list, IPC recognized that spawn timing and distribution data were essential to balance the management of the water resources flowing through the HCC and the fall chinook salmon that are reliant on habitat downstream of the project. Since 1991, the periodicity of aerial surveys during spawning within the mainstem Snake River, and within the lower portions of its major tributaries, has increased. Also, remote underwater video survey techniques have been used to document the use of potential spawning areas in water too deep to be visually surveyed from the air. These two methods have significantly increased our understanding of how spawning fall chinook salmon use the available habitat downstream of the HCC.

The following points provide a brief summary of the timing and distribution of fall chinook spawning within the mainstem Snake River:

Timing • Fall chinook salmon spawn within the mainstem Snake River between mid- October and early December. • Spawning can begin as early as the first week of October (2000) and as late as the first week of November (1991) but is generally initiated during mid-October. • The peak of spawning activity generally occurs between the last week of October and the first week of November. • The bulk of spawning (95%) is generally completed by mid-November, but absolute completion occurs by the last week of November and can be protracted into the first week of December. • The overall timing of redd construction appears to be related to the total number of adults allowed to escape to the spawning grounds upstream of Lower Granite Dam. As the escapement increases, spawning tends to begin earlier, peak within a short time, and end earlier than when escapement is depressed. • Spawning occurs during the descending limb of the thermal regime of the river, beginning generally as water temperatures reach 16.0 °C; however, we have observed that spawning can be initiated when temperatures are as high as 17.0 °C, and as low as 12.0 °C. • The spawn timing, and water temperatures associated with redd construction activity of fall chinook salmon within the Snake River, are consistent with timing and thermal conditions reported for similar stocks of fall chinook.

Distribution • Spawning (both shallow and deep) has been observed throughout the free-flowing reach of the Snake River from about RKM 239 to RKM 397.

Hells Canyon Complex Page 15 Evaluation of Anadromous Fish Potential Idaho Power Company

• Because water temperatures in the early fall tend to be slightly cooler downstream and warmer upstream of the mouth of the Salmon River, it was originally thought that initial spawning, and a larger overall proportion of spawning, would take place in the lower sections of the Snake River. However, data collected between 1991 and 2000 show that spawning begins more often in the upper section of the Snake River and that as much as 70% of spawning occurs in that section. • As of 2000, 85 shallow and 29 deep-water spawning locations have been documented within the mainstem Snake River. However, this compilation of spawning sites should not be viewed as definitive: as the spawning population continues to increase, new spawning sites may be observed. • The number of redds observed within the mainstem Snake River (shallow and deep-water inclusive) has increased over recent years from 46 in 1991 to 346 in 2000. • In the mainstem Snake River, redds constructed within deep water (unsurveyed previous to 1991) have been documented to account for as much as 50% of the total spawning activity, but more commonly comprise about 30%. • The absolute number of specific locations used for spawning has tended to increase as escapement numbers have increased. However, even at the highest level of use (1999—373 redds), only 35% of shallow and 38% of deep-water sites were used to the maximum ever documented. This evidence also suggests that full seeding, or carrying capacity in terms of spawning, has not been attained at even the highest escapement levels.

Based on the results of redd surveys conducted from 1991 to 2000, we conclude that spawning behavior within the mainstem Snake River is not detrimentally affected by HCC operations. Redd counts have increased since IPC began providing stable flows during the spawning season. Although adults are present in the mainstem Snake River and can begin spawning when water temperatures are relatively high, there have been no reported or documented instances of pre-spawn mortality. Also, virtually all redds within the mainstem Snake River are constructed at temperatures between 16.0 and 7.0 °C, similar to thermal values reported in the literature for fall chinook in the wild, and during a seasonal time frame similar to that of the Hanford Reach population of the Columbia River and fish returning to the Clearwater and Grande Ronde rivers. A specific note of interest is that fall chinook salmon are supposedly throughout the entire mainstem Snake River inclusively, and that while river temperatures are cooler within the lower sections of the free-flowing reach, spawning generally begins earlier within the upper section at relatively warmer temperatures. It would seem that if the fish chose to avoid the warmer temperatures, spawning would be initiated earlier within the lower sections at cooler temperatures. This evidence suggests that fall chinook salmon within the mainstem Snake River are following a life history pattern that is no different from that of other local populations, and that therefore they should not be experiencing increased risks to stress or mortality.

Page 16 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

7. ACKNOWLEDGMENTS

I first wish to thank our helicopter pilot (Jim Pope, Sr.; Valley Helicopter) and his ground crew; for 10 years they have kept us safe in the air. I would also like to acknowledge the USFWS, USFS, WDFW, and NPT for sharing costs and data associated with our aerial surveys and deep-water redd searches. Technicians Bob Poertner, Mike McLeod, Carl Pedersen, Rob Warburton, Stan Pierce, and Phil Bates provided assistance in data collection during deep- water searches. Beamers Hells Canyon Tours, River Quest, and Snake River Adventures provided transportation and lodging at key locations along the river enabling us to make efficient use of our time. Finally, I’d like to thank Tim Stuart and a host of other boat pilots for keeping us safe on the water and for driving “endless” transects during deep-water redd searches.

8. LITERATURE CITED

Armour, C. L. 1990. Options for reintroducing salmon and steelhead above mid-Snake River dams. U.S. Department of the Interior, Fish and Wildlife Service Research and Development, Washington, D.C.

Carlson, C., and M. Dell. 1990. Vernita Bar monitoring for 1989–1990. Annual report to Grant County Public Utility District, Ephrata, WA.

Carlson, C., and M. Dell. 1992. Vernita Bar monitoring for 1991–1992. Annual report to Grant County Public Utility District, Ephrata, WA.

Chandler, J. A., P. A. Groves, and P. A. Bates. 2001. Existing habitat conditions of the mainstem Snake River habitat formerly used by anadromous fish. In: J. A. Chandler, editor. Chapter 5. 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. W., D. E. Weitkamp, T. L. Welsh, M. B. Dell, and T. H. Shadt. 1986. Effects of river flow on the distribution of chinook salmon redds. Transactions of the American Fisheries Society 115:537-547.

Chapman, W. M. 1943. The spawning of chinook salmon in the main Columbia River. Copeia 1943:168-170.

Connor, W. P., A. P. Garcia, H. L. Burge, and R. H. Taylor. 1993. Fall chinook salmon spawning in free-flowing reaches of the Snake River. Pages 1-29 in D. W. Rondorf and K. F. Tiffan, editors. Identification of the spawning, rearing, and migratory requirements of fall chinook salmon in the Columbia River basin. 1991 Annual Report to Bonneville Power Administration, Contract DE-AI79-91BP21708, Portland, OR.

Coutant, C. C. 1977. Compilation of temperature preference data. Journal of the Fisheries Research Board Canada 34:739-745.

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3DJH +HOOV &DQ\RQ &RPSOH[ Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

Garcia, A. P., W. P. Connor, R. D. Nelle, R. D. Waitt, E. A. Rockhold, and R. S. Bowen. 1997. Fall chinook spawning ground surveys in the Snake River, 1995. Pages 1-17 in D. W. Rondorf and K. F. Tiffan, editors. Identification of the spawning, rearing, and migratory requirements of fall chinook salmon in the Columbia River basin. 1995 Annual Report to Bonneville Power Administration, Contract DE-AI79-91BP21708, Portland, OR.

Garcia, A. P., and six coauthors. 1999. Chapter 2: Fall chinook spawning ground surveys in the Snake River basin upriver of Lower Granite Dam, 1998. Pages 10-28 in A. P. Garcia, editor. Spawning distribution of fall chinook salmon in the Snake River. 1998 Annual Report to Bonneville Power Administration, Contract 98-AI-37776, Project 9801003, Portland, OR.

Garcia, A. P., and six coauthors. 2000. Chapter 2: Fall chinook salmon spawning ground surveys in the Snake River, 1999. Pages 10-28 in A. P. Garcia, editor. Spawning distribution of fall chinook salmon in the Snake River. 1999 Annual Report to Bonneville Power Administration, Contract 98-AI-37776, Project 9801003, Portland, OR.

Garcia, A. P., and six coauthors. 2001a. Chapter 2: Fall chinook salmon spawning ground surveys in the Snake River, 2000. Pages 14-32 in A. P. Garcia, editor. Spawning distribution of fall chinook salmon in the Snake River. 2000 Annual Report to Bonneville Power Administration, Contract 98-AI-37776, Project 9801003, Portland, OR.

Garcia, A. P., and seven coauthors. 2001b. Chapter 1: Spawning distribution of supplemented fall chinook salmon in the Snake River basin upriver of Lower Granite Dam. Pages 1-13 in A. P. Garcia, editor. Spawning distribution of fall chinook salmon in the Snake River. 2000 Annual Report to Bonneville Power Administration, Contract 98-AI-37776, Project 9801003, Portland, OR.

Gilbert, C. H., and B. W. Evermann. 1892. A report upon investigations in the Columbia River basins, with descriptions of four new species of fish. U.S. Fish Commission Bulletin 14:169-207.

Groves, P. A. 1993. Habitat available for, and used by, fall chinook salmon within the Hells Canyon Reach of the Snake River. Idaho Power Company, Boise, ID.

Groves, P. A., and J. A. Chandler. 1996. A summary of fall chinook salmon (Oncorhynchus tshawytscha) redd surveys within the Hells Canyon reach of the Snake River, Idaho: 1991–1995. Final Report of Idaho Power Co. (Permit 851) to U.S. National Marine Fisheries Service, Boise, ID.

Groves, P. A., and J. A. Chandler. 1999. Spawning habitat used by fall chinook salmon in the Snake River. North American Journal of Fisheries Management 19:912-922.

Groves, P. A., and A. P. Garcia. 1998. Designs for two carriers used to deploy an underwater video camera from a boat. North American Journal of Fisheries Management 18:1004-1007.

Hells Canyon Complex Page 19 Evaluation of Anadromous Fish Potential Idaho Power Company

Healey, M. C. 1991. Life history of chinook salmon (Oncorhynchus tshawytscha). Pages 313-393 in C. Groot and L. Margolis, editors. Pacific salmon life histories. University of British Columbia, Vancouver.

IDFG (Idaho Department of Fish and Game). 1953. The size and timing of runs of anadromous species of fish in the Idaho tributaries of the Columbia River. Report of Idaho Fish and Game to U.S. Army Corps of Engineers, Boise, ID.

IPC (Idaho Power Company). 1978. Redd counts—fall chinook salmon—Hells Canyon to Lewiston—November 15, 1978. Memorandum from Wendell Smith to Logan Lanham and Paul Jauregui. Stored at IPC, Environmental Department, Boise, ID.

IPC. 1990. Fall chinook interim recovery plan and study. Idaho Power Company, Boise, ID.

Irving, J. S., and T. C. Bjornn. 1981. Status of Snake River fall chinook salmon in relation to the Endangered Species Act. U.S. Fish and Wildlife Service, Moscow, ID.

Mendel, G., D. Milks, R. Bugert, and K. Petersen. 1992. Upstream passage and spawning of fall chinook salmon in the Snake River, 1991. Lyons Ferry Evaluation Program, Cooperative Agreement 14-16-0001-91502. To Lower Snake River Compensation Plan, U.S. Fish and Wildlife Service, Boise, ID.

Mendel, G., D. Milks, M. Clizer, and R. Bugert. 1994. Upstream passage and spawning of fall chinook salmon in the Snake River. In H. L. Blankenship and G. W. Mendel, editors. Upstream passage, spawning, and stock identification of fall chinook salmon in the Snake River, 1992. Bonneville Power Administration Annual Report 1992–1993 to U.S. Department of Energy, Portland, OR.

Murray, C. B., and J. D. McPhail. 1988. Effect of incubation temperature on the development of five species of Pacific salmon (Oncorhynchus) embryos and alevins. Canadian Journal of Zoology 66:266-273.

NMFS (National Marine Fisheries Service). 1992. Threatened status for Snake River spring/summer chinook salmon, threatened status for Snake River fall chinook salmon. Final Rule, U.S. Office of the Federal Register 57:78 (22 April 1992).

NMFS. 2000. Draft biological opinion—ongoing operation of Idaho Power Company’s Hells Canyon Complex (FERC No. 1971) and hatchery facilities. U.S. Department of Commerce, Washington, D.C.

Olson, P. A., and R. F. Foster. 1955. Temperature tolerance of eggs and young of Columbia River chinook salmon. Transactions of the American Fisheries Society 85:203-207.

Swan, G. A. 1989. Chinook salmon spawning surveys in deep waters of a large, regulated river. Regulated Rivers: Research and Management 4:355-370.

Page 20 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

Van Dusen, H. G. 1903. Annual reports of the Department of Fisheries of the State of Oregon to the Legislative Assembly, Twenty-Second Regular Session. Salem, OR.

WDFW (Washington Department of Fish and Wildlife). 1987. Fall chinook redd counts on the Snake River and tributaries. Memorandum from Bob Bugert to Larry Wimer and Ken Witty. Stored at IPC, Environmental Department, Boise, ID.

WDFW. 1988. 1988 fall chinook redd counts on the Snake River and tributaries. Memorandum from Bob Bugert. Stored at IPC, Environmental Department, Boise, ID.

WDFW. 1990. Fall chinook salmon redd counts on the Snake River and tributaries. Memorandum from Bob Bugert. Stored at IPC, Environmental Department, Boise, ID.

WDFW. 1991. Fall chinook natural production on the Snake River and tributaries. Memorandum from Bob Bugert. Stored at IPC, Environmental Department, Boise, ID.

Welsh, T. L., S. H. Gebhards, H. E. Metsker, and R. V. Corning. 1965. Inventory of Idaho streams containing anadromous fish including recommendations for improving production of salmon and steelhead. Idaho Fish and Game Status Report. Boise, ID.

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Table 3. The total number of shallow and deep-water redds observed in the Snake River between Asotin, Washington, and the Hells Canyon Dam (RKM 227–399), 1991–2000.

Shallow Redds Deep Redds Year (Aerial Observations) (Video Observations) Total Redds 1991 41 5 46 1992 46 1 47 1993 60 67 127 1994 51 16 67 1995 41 30 71 1996 71 42 113 1997 49 9 58 1998 135 50 185 1999 273 100 373 2000 255 91 346

Table 4. Total number of redds observed during aerial surveys of the major tributaries to the Snake River, 1991–2000.

Number of redds observed each year Tributary 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Clearwater River 1 4 26 36 37 20 69 72 78 184 172

Grande Ronde River 2 0 5 49 15 18 20 55 24 13 8

Salmon River 1 nf 1 3 1 2 1 1 3 0 0

Imnaha River 2 4 3 4 0 4 3 3 13 9 9 Tributary Total 8 35 92 53 44 93 131 118 206 189

1 From Bill Arnsberg, Nez Perce Tribe, unpublished data 2 From USFWS and IPC, unpublished data

Page 24 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

Table 5. Historic fall chinook salmon redd surveys and corresponding number of redds identified.

Number of River kilometers Total number of Year surveys Range of survey dates Covered redds observed

1959 1 Unknown Unknown 227–399 28

1960 1 1 13 Dec 227–399 4

1964 5 1 17 Nov 203–434 168

1967 1 Unknown Unknown 227–399 188

1969 1 Unknown Unknown 227–399 568

1974 2 Unknown Unknown 303–399 16

1975 2 Unknown Unknown 303–399 10

1976 2 Unknown Unknown 303–399 13

1978 3 1 15 Nov 227–399 132

1986 4 1 09 Nov 227–399 7

1987 4 2 09 Nov, 23 Nov 227–399 66

1988 4 2 14 Nov, 01 Dec 227–399 64

1989 4 2 13 Nov, 27 Nov 227–399 58

1990 4 3 12 and 26 Nov, 11 Dec 227–399 37

1 Data from Irving and Bjornn 1981. 2 Data from Joel Hurtado, Oregon Department of Fish and Wildlife, personal communication (1974–1976). 3 Data from Idaho Power Company memorandum, Wendell Smith, dated 16 November 1978. 4 Data from Robert Bugert, Washington Department of Fisheries, departmental memorandums (1987–1990). 5 Data from memorandum of J.M. Shelton of the U.S. Fish and Wildlife Service to Idaho Department of Fish and Game.

Hells Canyon Complex Page 25 Evaluation of Anadromous Fish Potential Idaho Power Company

Table 6a. The number of redds constructed during early periods of spawning, downstream of the Salmon River confluence, when temperatures are dropping from just above 17.0 to 14.0 °C, 1991–2000.

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Date water temperature at 10/09 10/06 10/07 10/04 10/04 10/01 10/06 10/08 10/01 9/28 17.0 °C Redds constructed 0 0 0 0 0 0 0 0 0 0 prior to 17.0 °C Date water temperature at 10/17 10/14 10/13 10/18 10/06 10/14 10/09 10/11 10/04 10/07 16.0 °C Redds constructed between 17.0 and 0 0 0 0 0 0 0 0 0 0 16.0 °C Date water temperature at 10/18 10/15 10/19 10/22 10/12 10/16 10/12 10/15 10/16 10/09 15.0 °C Redds constructed between 16.0 and 0 0 0 0 0 0 0 0 0 0 15.0 °C Date water temperature at 10/24 10/25 10/22 10/24 10/18 10/19 10/18 10/17 10/18 10/15 14.0 °C Redds constructed between 15.0 and 1 0 2 0 0 0 1 0 2 0 14.0 °C Total redds downstream 25 31 108 30 38 57 34 48 80 116

Page 26 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

Table 6b. The number of redds constructed during early periods of spawning, upstream of the Salmon River confluence, when temperatures are dropping from just above 17.0 to 14.0 °C, 1991–2000.

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Date water temperature at 10/18 10/14 10/09 10/16 10/11 10/13 10/10 10/15 10/10 10/07 17.0 °C Redds constructed 0 0 0 0 0 0 0 0 0 1 prior to 17.0 °C Date water temperature at 10/24 10/23 10/19 10/22 10/17 10/17 10/15 10/17 10/16 10/13 16.0 °C Redds constructed between 17.0 and 0 0 0 1 0 0 0 0 3 5 16.0 °C Date water temperature at 10/28 10/30 10/25 10/28 10/20 10/21 10/17 10/19 10/19 10/22 15.0 °C Redds constructed between 16.0 and 0 0 0 4 4 2 0 0 3 23 15.0 °C Date water temperature at 10/30 11/04 10/30 11/01 10/26 10/27 10/21 10/26 10/27 10/30 14.0 °C Redds constructed between 15.0 and 0 2 5 4 12 23 0 17 35 99 14.0 °C Total redds upstream 22 16 19 37 33 56 24 137 293 230

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Page 28 Hells Canyon Complex 148.4

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156.8 r 157.3

159.7 160.8 160.9

162.3

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Hells Canyon Project - FERC No. 1971 Legend Tech Report E.3.1-3 Figure 1a Distribution of spawning and total number of redds Redd Locations observed annually at spawning locations identified during aerial surveys of the Snake River between river miles 148 and 188: 1991-2000 River

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Page 30 Hells Canyon Complex r

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213.2 213.5 213.7 214.6 Pittsburg Landing 215.6

Hells Canyon Project - FERC No. 1971 Legend Tech Report E.3.1-3 Figure 1b Distribution of spawning and total number of redds observed annually at spawning locations identified Redd Locations during aerial surveys of the Snake River between river miles 188 and 216: 1991-2000 River

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Page 32 Hells Canyon Complex Pittsburg Landing

216.2

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218.7 218.5 219.0 219.2

222.7 222.9 223.1

224.7 225.1 225.0

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240.4 240.6 241.0

242.7

243.5 243.9 244.5

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Hells Canyon Project - FERC No. 1971 Legend Tech Report E.3.1-3 Figure 1c Distribution of spawning and total number of redds observed annually at spawning locations identified Redd Locations during aerial surveys of the Snake River between river miles 216 and 247: 1991-2000 River Scale 1:245,000 Miles 1 0.5 0 1 2 3 4 Evaluation of Anadromous Fish Potential Idaho Power Company

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Page 34 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

1.00

0.90

0.80

0.70

0.60 1991 1992 1993 1994 1995 0.50 1996 1997 1998 1999

Cumulative redd count 2000 0.40

0.30

0.20

0.10

0.00 40 41 42 43 44 45 46 47 48 49 50 51 52 Julian week of survey flights

Figure 2. Cumulative percent completion of spawning within the Snake River, by Julian week, 1991–2000. Data used for this graph is based on surveys conducted at the beginning of each Julian week.

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1.00

0.90

0.80

0.70

0.60

0.50 Cumulative redd count 0.40

0.30

0.20

0.10

0.00 40 41 42 43 44 45 46 47 48 49 50 51 52 Julian week of survey flights

1991 1992 1998 1999 2000

Figure 3. A comparison of cumulative percent completion of spawning for 1991, 1992, 1998, 1999, and 2000.

Page 36 Hells Canyon Complex Idaho Power Company Chapter 1: Fall Chinook Spawn Timing and Distribution

30.0

28.0

26.0

24.0

22.0

20.0

18.0

16.0

14.0 Temperature (C) Temperature

12.0

10.0

8.0

6.0

4.0

2.0

0.0 25-May- 24-Jul-96 22-Sep- 21-Nov- 20-Jan- 21-Mar- 20-May- 19-Jul-97 17-Sep- 16-Nov- 15-Jan- 16-Mar- 15-May- 14-Jul-98 12-Sep- 11-Nov- 10-Jan- 96 96 96 97 97 97 97 97 98 98 98 98 98 99 Date

Rkm 348 Rkm 556 Swan Falls Dam

Hells Canyon Complex Page 37 Evaluation of Anadromous Fish Potential Idaho Power Company

30 Number of spawning sites

y = 0.0266x - 2.3381 10 R 2 = 0.7984

0 0 500 1000 1500 2000 2500 Escapement at Low er Granite Dam

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