U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2016–1197

Prepared in cooperation with the U.S. Army Corps of Engineers

Evaluation of the Biological and Hydraulic Performance of 

the Portable Floating Fish Collector at Cougar Reservoir and 

Dam, Oregon, September 2015–January 2016
Cover: Photographs showing changing water elevation on the first week of each of 

9 months at Cougar Dam and cul-de-sac area of Cougar Reservoir, Oregon.

Photographs by Colin D. Smith, U.S. Geological Survey, September 2015–May 2016.
Evaluation of the Biological and Hydraulic Performance of 

the Portable Floating Fish Collector at Cougar Reservoir 

and Dam, Oregon, September 2015–January 2016

By John W. Beeman, Scott D. Evans, Philip V. Haner, Hal C. Hansel, Amy C. Hansen, Gabriel S. Hansen, 

Tyson W. Hatton, Eric E. Kofoot, and Jamie M. Sprando

Prepared in cooperation with the U.S. Army Corps of Engineers

Open-File Report 2016–1197

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

For more information on the USGS—the Federal source for science about the Earth,

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Suggested citation:

Beeman, J.B., Evans, S.D., Haner, P.V., Hansel, H.C., Hansen, A.C., Hansen, G.S., Hatton, T.W., Kofoot, E.E., 

and Sprando, J.M., 2016, Evaluation of the biological and hydraulic performance of the portable floating fish 

collector at Cougar Reservoir and Dam, Oregon, September 2015–January 2016: U.S. Geological Survey OpenFile Report 2016–1197, 98 p., https://doi.org/10.3133/ofr20161197. 

ISSN 2331-1258 (online)
iii

Acknowledgments

This study was completed with assistance from many people and organizations. The staff at 

Oregon State University and cooperators on the Wild Fish Surrogate Study provided the hatchery-origin 

study fish, and the staff at McKenzie Hatchery provided space and facilities for us to hold them. U.S. 

Army Corps of Engineers staff at Cougar Dam and Todd Pierce and Jane Dalgliesh of the Willamette 

Valley Project were instrumental in coordinating our activities to install equipment and monitor the 

tagged fish near the dam, as were Scott Fielding and Mary Karen Scullion at the Portland District office. 

Our administrative and science colleagues at the Columbia River Research Laboratory (particularly 

Theresa Liedtke, Matthew Sholtis, and Nick Swyers) contributed greatly to this study. This report was 

improved by reviews of Collin Smith and Bernadette Graham Hudson through the U.S. Geological 

Survey and U.S. Army Corps of Engineers peer review programs. This study was funded by the U.S. 

Army Corps of Engineers under contract W66QKZ51608687. 
iv

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v 

Contents

Acknowledgments.......................................................................................................................................................iii

Abstract ...................................................................................................................................................................... 1

Introduction................................................................................................................................................................. 2

Methods...................................................................................................................................................................... 6

Dam Operations and Environmental Conditions ..................................................................................................... 6

Operation and Hydraulic Indicators of PFFC Performance ..................................................................................... 7

Operating Conditions and Treatment Schedule................................................................................................... 7

Water Velocities .................................................................................................................................................. 9

PIT Interrogator ................................................................................................................................................... 9

Fish Collection by the PFFC................................................................................................................................ 9

Acoustic- and PIT-Tag Telemetry............................................................................................................................ 9

Transmitters ........................................................................................................................................................ 9

Handling, Tagging, and Release ....................................................................................................................... 10

Acoustic Telemetry Detection System............................................................................................................... 12

Removing False-Positive Records..................................................................................................................... 15

Estimating Fish Positions .................................................................................................................................. 15

Travel Times...................................................................................................................................................... 16

Depths in the Cul-de-Sac .................................................................................................................................. 16

Temperature Selection ...................................................................................................................................... 16

Spatial Intensity of Use...................................................................................................................................... 16

Movement Behaviors......................................................................................................................................... 17

In the Cul-de-Sac........................................................................................................................................... 17

Near the PFFC Entrance ............................................................................................................................... 18

Collection in the PFFC and Dam Passage ........................................................................................................ 18

Results...................................................................................................................................................................... 19

PFFC Operation and Data Collection Periods....................................................................................................... 19

Dam Operations and Environmental Conditions ................................................................................................... 20

Operation and Hydraulic Indicators of PFFC Performance ................................................................................... 22

Operating Conditions and Treatment Schedule................................................................................................. 22

Water Velocities ................................................................................................................................................ 24

Fish Collection by the PFFC.............................................................................................................................. 27

Handling, Tagging, and Release........................................................................................................................... 30

Travel Times ......................................................................................................................................................... 31

Depths in the Cul-de-Sac ...................................................................................................................................... 32

Temperature Selection.......................................................................................................................................... 37

Spatial Intensity of Use ......................................................................................................................................... 38

In the Cul-de-Sac .............................................................................................................................................. 38

Near the PFFC Entrance................................................................................................................................... 40

Movements Behaviors........................................................................................................................................... 42

In the Cul-de-Sac .............................................................................................................................................. 42

Near the PFFC Entrance................................................................................................................................... 44

Collection in the PFFC and Dam Passage............................................................................................................ 47

Discussion ................................................................................................................................................................ 51

References Cited...................................................................................................................................................... 54
vi 

Appendix A. Summary of Dam Operating Conditions Calculated from Hourly Data at Cougar Dam, Oregon, 

2015–16.................................................................................................................................................................... 58

Appendix B. Performance of the Portable Floating Fish Collector Passive Integrated Transponder Interrogator .... 59

Appendix C. Transmitter Life and Transmitter Loss Tests ....................................................................................... 62

Appendix D. Positioning System Accuracy ............................................................................................................... 65

Appendix E. Summary of Portable Floating Fish Collector Operating Conditions Collected by U.S. Army Corps 

of Engineers Staff at Cougar Reservoir and Dam, Oregon, 2015–16 ....................................................................... 67

Appendix F. Comparison of Temperature Profiles Across the Cul-de-Sac at Cougar Reservoir and Dam, 

Oregon, 2015–16...................................................................................................................................................... 69

Appendix G. Graphs of Utilization Distributions Overlap Indices Comparing Utilization Distributions of 

Acoustic+Passive Integrated Transponder-Tagged Juvenile Chinook Salmon in the Cul-de-Sac of Cougar 

Reservoir and Dam, Oregon, 2015–16 ..................................................................................................................... 72

Appendix H. Utilization Distributions from Acoustic+Passive Integrated Transponder-Tagged Juvenile Chinook 

Salmon in the Cul-de-Sac of Cougar Reservoir and Dam, Oregon, 2015–16........................................................... 75

Appendix I. Rose Diagrams of Mean Fish Travel Directions at the Portable Floating Fish Collector at Cougar 

Dam, Oregon, 2015–16 ............................................................................................................................................ 95

Figures

Figure 1. Graphic of Willamette River Basin Project showing Cougar Reservoir and Dam, Oregon........................ 3

Figure 2. Photograph of water temperature control tower (background) and the portable floating fish collector in 

the forebay of Cougar Dam, Oregon, 2014................................................................................................................ 4

Figure 3. Photograph of portable floating fish collector (PFFC) during construction showing pertinent features, 

Cougar Reservoir, Oregon. Photograph by Collin D. Smith, U.S. Geological Survey, March 26, 2104 ..................... 5

Figure 4. Photograph showing position of the portable floating fish collector (PFFC) relative to the water 

temperature control tower in the cul-de-sac of Cougar Dam and Reservoir, Oregon, July 2015 ............................... 5

Figure 5. Orthoimage showing arrays of autonomous hydrophones (small circles) deployed in Cougar 

Reservoir, Oregon, 2015–2016................................................................................................................................ 12

Figure 6. Photographs showing locations of cabled hydrophones nearest the water temperature control tower 

at Cougar Dam, Oregon, 2015–16........................................................................................................................... 14

Figure 7. Photograph showing locations of hydrophones deployed 2.5 meters (m) below the water surface from 

floating platforms near the portable floating fish collector and water temperature control tower at Cougar Dam, 

Oregon, 2015–16..................................................................................................................................................... 15

Figure 8. Graphs of mean daily project discharge and head over the weir gates, and reservoir elevation and 

water temperature at Cougar Reservoir, Oregon, January 1, 2015–April 23, 2016 ................................................. 21

Figure 9. Contour plot of hourly temperature in degrees Celsius by water depth of sensors in the Cougar 

Reservoir, Oregon, March 1, 2015–March 1, 2016 .................................................................................................. 22

Figure 10. Graph of 2015 velocity measurements during HDR Engineering, Inc. (HDR) recommissioning and 

USGS sampling in the flume of the portable floating fish collector (PFFC) at Cougar Reservoir, Oregon, 

February 2015 ......................................................................................................................................................... 24

Figure 11. Hydraulic profile graphs of velocity magnitude, gradient, and acceleration for distance from the 

portable floating fish collector (PFFC) opening at Cougar Reservoir, Oregon, 2014–15 ......................................... 25

Figure 12. Three-dimensional view of sampled points ........................................................................................... 26

Figure 13. Graph of fork lengths of juvenile Chinook salmon collected at the portable floating fish collector 

(PFFC), Cougar Reservoir, Oregon, 2015–16 ......................................................................................................... 27

Figure 14. Graphs showing frequency of juvenile Chinook salmon and bycatch captured by block and 

treatment at the portable floating fish collector (PFFC), Cougar Reservoir, Oregon, 2015–16 ................................ 28
vii 

Figure 15. Graphs of juvenile Chinook salmon mean catch per unit effort (CPUE) per 24 hours of trap 

operation by block and treatment at the portable floating fish collector (PFFC), Cougar Reservoir, Oregon, 

2015–16................................................................................................................................................................... 29

Figure 16. Graphs of travel time (days) from release of Chinook salmon to first detection at the log boom and 

from the log boom to within 10 meters (m) of the entrance to the water temperature control tower (Tower) or the 

portable floating fish collector (PFFC) after September 14, 2015, Cougar Reservoir, Oregon, 2015–16................. 32

Figure 17. Boxplots of the hourly depths (in meters) of acoustic+PIT-tagged juvenile Chinook salmon with 

position estimates within 20 meters of the entrance to the portable floating fish collector (PFFC) at Cougar 

Reservoir, Oregon, September 14, 2015–January 26, 2016.................................................................................... 34

Figure 18. Boxplots of the hourly depths (in meters) of acoustic+PIT-tagged juvenile Chinook salmon with 

position estimates within 20 meters of the entrance to the water temperature control tower at Cougar Reservoir, 

Oregon, September 14, 2015–January 26, 2016..................................................................................................... 35

Figure 19. Graphs of acoustic+PIT-tagged fish depths by month (blue bars) and cumulative by 3-meter bins 

in the cul-de-sac at Cougar Reservoir, Oregon, 2015–16........................................................................................ 36

Figure 20. Graphs of mean daily fish depth within 20 meters of the portable floating fish collector entrance 

(PFFC) and within 20 meters of the water temperature control tower entrance (Tower) and hourly water 

temperatures (in degrees Celsius) in Cougar Reservoir, Oregon, 2015–16 ............................................................ 37

Figure 21. Graphs of the standardized resource selection index for fish positioned within 20 meters of the 

portable floating fish collector entrance (PFFC) and within 20 meters of the water temperature control tower 

entrance (Tower) at Cougar Reservoir, Oregon, 2015–16....................................................................................... 38

Figure 22. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon in the 

0–3 meter depth bin at Cougar Reservoir, Oregon, September 2015–January 2016 .............................................. 39

Figure 23. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon in the 

3–6 meter depth bin at Cougar Reservoir, Oregon, September 2015–January 2016 .............................................. 40

Figure 24. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon near 

the portable floating fish collector (PFFC) in the 0–3 meter (m) depth bin at Cougar Reservoir, Oregon, 

September 2015–January 2016............................................................................................................................... 41

Figure 25. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon near 

the portable floating fish collector (PFFC) in the 3–6 meter (m) depth bin at Cougar Reservoir, Oregon, 

September 2015–January 2016............................................................................................................................... 42

Figure 26. Graphs of the distribution of the median tortuosity of acoustic+PIT-tagged juvenile Chinook salmon 

swimming in the 0–3 meter (m) depth bin at Cougar Reservoir, Oregon, September 2015–January 2016 ............. 43

Figure 27. Graphs of the distribution of the median tortuosity of acoustic+PIT-tagged juvenile Chinook salmon 

swimming in the 3–6 meter (m) depth bin at Cougar Reservoir, Oregon, September 2015–January 2016 ............. 44

Figure 28. Graphs of movements of eight randomly selected acoustic+PIT-tagged juvenile Chinook salmon 

near the portable floating fish collector (PFFC) during the High treatment in the night at Cougar Reservoir, 

Oregon, 2015–16..................................................................................................................................................... 46

Figure 29. Graphs of movements of five acoustic+PIT-tagged juvenile Chinook salmon collected in the 

portable floating fish collector (PFFC; figure parts A–E) at Cougar Reservoir, Oregon, 2015–16............................ 49

Figure 30. Graph showing proportion of released acoustic+PIT-tagged fish detected during treatment 

operations of the portable floating fish collector (PFFC) at zones in Cougar Reservoir, Oregon, 2015–16 ............. 51
viii

Tables

Table 1. Planned portable floating fish collector (PFFC) operations, Cougar Reservoir and Dam, Oregon, 

2015–2016................................................................................................................................................................. 7

Table 2. Passage and fish collection efficiency definitions ..................................................................................... 19

Table 3. Study periods based on operating conditions and data collection methods at Cougar Dam and 

Reservoir, Oregon, 2015–16.................................................................................................................................... 19

Table 4. Actual portable floating fish collector (PFFC) operations at Cougar Reservoir, Oregon, during the 

randomized-block treatment schedule, 2015–16 ..................................................................................................... 23

Table 5. Summary of mortality of juvenile Chinook salmon collected in the portable floating fish collector 

(PFFC), Cougar Reservoir, Oregon, March 2, 2015–March 1, 2016........................................................................ 29

Table 6. Summary statistics of fork length and weight of acoustic and passive integrated transponder 

(PIT) tagged hatchery and wild juvenile Chinook salmon at Cougar Reservoir, Oregon, 2015. ............................... 30

Table 7. Summary of the mean of the median hourly depths (in meters) of each fish positioned within 

20 meters of the water temperature control tower (Tower) and portable floating fish collector (PFFC) from 

September 14, 2015, to the 90th percentile of each acoustic tag life in Cougar Reservoir, Oregon, 2015–16. ....... 33

Table 8. Reservoir passage efficiency, forebay passage efficiency, and dam passage efficiency from acoustictagged juvenile Chinook salmon at Cougar Reservoir, Oregon, 2015–16 ............................................................... 48

Table 9. Passage metric estimates and lower and upper 95-percent confidence intervals during portable 

floating fish collector treatments from acoustic-tagged juvenile Chinook salmon at Cougar Reservoir, Oregon, 

2015–16................................................................................................................................................................... 48
ix

Conversion Factors

Inch/Pound to International System of Units 

Multiply By To obtain

foot (ft) 0.3048 meter (m)

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

International System of Units to Inch/Pound

Multiply By To obtain

millimeter (mm) 0.03937 inch (in.)

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

kilometer (km) 0.5400 mile, nautical (nmi) 

meter per second (m/s) 3.281 foot per second (ft/s)

liter (L) 0.2642 gallon (gal)

milligram 0.00003527 ounce, avoirdupois (oz)

gram (g) 0.03527 ounce, avoirdupois (oz)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × °C) + 32.

Datum

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Elevation, as used in this report, refers to distance above the vertical datum.

Supplemental Information

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).
x 

Abbreviations

ADV Acoustic Doppler Velocimeter

AICc Akaike Information Criterion with an adjustment for effects of sample size

ANOVA analysis of variance 

BY broodstock year

CPUE catch per unit effort

dBBMM dynamic Brownian Bridge Movement Model

DE discovery efficiency

DPE dam passage efficiency 

DPETREAT dam passage efficiency during the PFFC treatments

EE entrance efficiency

FBE forebay passage efficiency

FCE fish collection efficiency

FCF fish collection effectiveness 

FPGL Fish Performance and Genetics Laboratory

GNSS Global Navigation Satellite System

GPS Global Positioning System

JSATS juvenile salmon acoustic telemetry system 

PFFC portable floating fish collector

PIT passive integrated transponder

PRI pulse rate interval

PVC polyvinyl chloride

rkm river kilometer

RO regulating outlet

RPE reservoir passage efficiency

UDs utilization distributions

UDOI utilization distribution overlap indices

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey
1 

Evaluation of the Biological and Hydraulic Performance of 

the Portable Floating Fish Collector at Cougar Reservoir 

and Dam, Oregon, September 2015–January 2016

By John W. Beeman, Scott D. Evans, Philip V. Haner, Hal C. Hansel, Amy C. Hansen, Gabriel S. Hansen, 

Tyson W. Hatton, Eric E. Kofoot, and Jamie M. Sprando

Abstract

The biological and hydraulic performance of a portable floating fish collector (PFFC) located in 

the cul-de-sac of Cougar Dam and Reservoir, Oregon, was evaluated during 2015–16. The PFFC, first 

commissioned in May 2014, was modified during winter 2014–15 to address several deficiencies 

identified during operation and testing in 2014. These modifications included raising the water inflow 

structures to reduce the depth and volume of inflow to improve the internal hydraulic profiles, and 

moving the anchors so the PFFC could be positioned closer to the existing reservoir outlet, a water 

temperature control tower. The PFFC was positioned about 18 meters (m) upstream of the intake of the 

water temperature control tower and faced into the prevailing water current. Like several floating 

surface collectors operating in the Pacific Northwest at the time, the PFFC used pumps to draw water 

and fish over an inclined plane, past dewatering screens, and into a collection area. The portable and 

experimental nature of the PFFC required a smaller size, shallower entrance (about 2.5-m deep), and 

smaller inflow rate (72 cubic feet per second [ft3

/s] inflow during the Low treatment, 122 ft3/s during the 

High treatment) than other collectors in the region. 

The collection of the target species, juvenile Chinook salmon (Oncorhynchus tshawytscha),

during 2015–16 was an order of magnitude larger than in 2014. Subyearling-age Chinook salmon 

comprised most of the catch (2,616 subyearling compared to 258 yearling) and was greatest during the 

spring during the High inflow treatment. Bycatch consisted predominantly of cyprinids and 

centrarchids. Trap mortality (fish found dead in the trap) of juvenile Chinook salmon, at 9.2 percent of 

the subyearlings and 5.0 percent of yearlings, was about 30 percent of the level in 2014. Fish mortality 

from handling the live catch was about 1 percent. 

Data from fish tagged with passive integrated transponder (PIT) tags and those with 

acoustic+PIT tags released near the head of the reservoir indicated the catch rates of the PFFC were 

low. Eight of the 1,497 PIT-tagged fish and 5 of the 534 acoustic+PIT-tagged fish were collected by the 

PFFC. Fish collection efficiencies—the number collected by the PFFC out of the number detected at the 

head of the forebay (FCEFB) or in the cul-de-sac (FCECDS) —were 0.002 and 0.003 during the Low 

treatment and 0.008 and 0.009 during the High treatment. The low FCEs were attributed to the 

following factors: 

• Few acoustic+PIT-tagged fish were detected within 10 m of the PFFC entrance, 

• Most fish were detected between the stern of the PFFC and the entrance to the tower, 

• Fish depths commonly were several times greater than the PFFC entrance depth, and

• Surface water temperatures were warm. 
2 

The data suggest that the shallow entrance and low inflow rate reduced fish guidance near the PFFC 

entrance and the hydraulic characteristics resulting from the outflow plumes (and perhaps water entering 

the temperature control tower) attracted fish to that area. Catch of juvenile Chinook salmon likely would 

increase if the collector entrance were deepened, the inflow rate were increased, and measures were 

taken to constrain fish presence to the area upstream of the trap entrance.

Introduction

A large number of high-head dams (those greater than 30 m tall) have been built in the Western 

United States for the purposes of water storage for flood control, irrigation, and hydropower production, 

resulting in blockages to the migrations of many aquatic species (U.S. Environmental Protection 

Agency, 2002). However, improvements in fish passage recently have been mandated at several sites as 

part of biological opinions related to operation of federally owned dams and relicensing agreements for 

privately owned dams (for example, Federal Energy Regulatory Commission, 2008; National Oceanic 

and Atmospheric Administration, 2008). Effective improvements to the migrations of anadromous fish 

such as salmon and steelhead (Oncorhynchus spp.) largely have been achieved with trap-and-haul 

programs to move adult fish upstream of one or more dams, but dam passage of downstream-migrating 

juvenile fish remains an issue. Challenges in passing juvenile salmonids at high-head dams include 

difficulty in achieving high passage probabilities and survival of fish volitionally passing existing 

structures, or difficulty in fish using alternative passage methods for transportation past the dams. These 

issues, common to many sites in the Western United States, are increasingly being addressed with 

various surface-collection methods that rely on pumps to create attraction flows over a series of 

dewatering screens and ultimately into a collection area or directly into a conveyance system leading to 

downstream passage. At the time of this report (2016), there had been seven installations of surface 

collectors to provide downstream passage at high-head dams in the Pacific Northwest, and most were 

still being studied to improve their passage success. These installations include the portable floating fish 

collector (PFFC) installed by the Portland District of the U.S. Army Corps of Engineers (USACE) at 

Cougar Dam and Reservoir, Oregon, in 2014. Cougar Dam has several properties that make collection 

and passage of juvenile salmonids challenging, including an existing passage route through a water 

temperature control structure, a low discharge volume, a large annual fluctuation in reservoir elevation, 

and an abundance of unmanaged floating woody debris. 

Cougar Dam, a 158-m-high rock-fill structure on the South Fork of the McKenzie River about 

63 km east of Springfield, Oregon, is one of 13 dams comprising the Willamette Project (Project) 

operated by the USACE in western Oregon (fig. 1). The primary purpose of the Project is flood-risk 

management, but it also is operated to provide water for hydroelectricity, irrigation, navigation, instream 

flows for wildlife, and recreation. Completed in 1964, the dam has a hydraulic capacity of 1,050 ft3

/s

and two Francis turbines capable of generating a total of 25 megawatts of power. During normal 

operations, all water passing through the dam goes through a water temperature control tower (tower) in 

a cul-de-sac at the western end of the dam (fig. 2). The tower allows waters from various depths to be 

selectively passed through the dam using a series of moveable gates to control downstream water 

temperatures. Discharge from the tower is routed through penstocks to the powerhouse, through a 

regulating outlet (RO), or both. A spillway with a pair of Tainter gates is located on the eastern side of 

the dam, but normally is not used. As part of the flood-risk management purpose of the dam, the forebay 

elevation is maintained at high levels during summer and low levels during winter. A maximum 

conservation pool elevation of 1,690 ft typically is reached in May, and a minimum flood-control pool 

elevation of 1,532 ft usually is reached in December and maintained until the end of January. 
3 

Figure 1. Graphic of Willamette River Basin Project showing Cougar Reservoir and Dam, Oregon. Graphic from 

U.S. Army Corps of Engineers.

The PFFC was designed as a portable means to test the efficacy of surface collection at Cougar 

Dam including the use of multiple inflow rates with a single series of dewatering screens. To meet these 

goals, a modular design was used to enable the PFFC to be moved among reservoirs as needed, and the 

scale of the device was smaller and less expensive than other collectors in the region (HDR

Engineering, Inc., 2012). The PFFC is about 20 × 20 m in size and uses pumps to draw water from the 

reservoir into a small flume, past dewatering screens, and into a collection box (fig. 3). The PFFC was 

designed for a maximum inflow of about 100 ft3

/s and a maximum inflow velocity of 6 ft/s (HDR

Engineering, Inc., 2012). The PFFC was to be placed near the existing entrance to the tower to take 

advantage of the prevailing water currents there (fig. 4). The PFFC was operated at two inflow 

conditions (hereinafter referred to as “treatments”) described further in section, “Operation and 

Hydraulic Indicators of PFFC Performance.” 
4 

Figure 2. Photograph of water temperature control tower (background) and the portable floating fish collector 

(PFFC; foreground) in the forebay of Cougar Dam, Oregon, 2014. Small floating platforms suspend hydrophones of 

an acoustic telemetry system. Photograph by Todd Pierce, U.S. Army Corps of Engineers, June 19, 2014.

The performance of the PFFC in 2014, the first year of operation, was less than expected. 

Evaluation by Beeman and others (2016) indicated that a total of 156 juvenile Chinook salmon 

(Oncorhynchus tshawytscha; mostly subyearling) were collected, including 1 of the 1,505 PIT-tagged 

fish released near the head of the reservoir. Data from acoustic+ PIT-tagged yearling Chinook salmon 

indicated that less than 1 percent of those detected within a 10 m of the PFFC entrance and within 6 m 

of the water surface were ultimately collected. The location plus the low and fluctuating water velocities 

near and within the PFFC were considered the primary factors limiting collection. Additionally, a 

temporary weir was required to reduce water inflow at the collection box in 2014. Modifications to raise 

the trap 46 cm, change the anchor locations to move the PFFC closer to the tower, modify the 

dewatering screens to reduce vibration, and address several other issues were made during winter 2014–

2015. This report describes the evaluation of the performance of the modified PFFC during fall and 

winter 2015–16. 
5 

Figure 3. Photograph of portable floating fish collector (PFFC) during construction showing pertinent features, 

Cougar Reservoir, Oregon. Photograph by Collin D. Smith, U.S. Geological Survey, March 26, 2104.

Figure 4. Photograph showing position of the portable floating fish collector (PFFC) relative to the water 

temperature control tower in the cul-de-sac of Cougar Dam and Reservoir, Oregon, July 2015. Rush Creek enters 

the reservoir in the upper left of the photograph. Photograph by Jamie M. Sprando, U.S. Geological Survey, July 

28, 2015.
6 

The study summarized in this report was similar to that conducted during the first year of PFFC 

operation (Beeman and others, 2016), and was designed to provide empirical information about the 

movement, behaviors, collection, and passage of juvenile Chinook salmon at the PFFC and tower to 

help inform decisions about future downstream passage solutions. The hydraulic performance of the 

PFFC was assessed by measuring water velocities near and within the PFFC flume. Measures of the 

biological performance were based on general fish collection by the PFFC, collection of tagged fish 

released near the head of the reservoir, and behaviors of fish near and within the PFFC identified using 

acoustic telemetry. The study was designed to provide information for the following objectives: 

• Estimate the seasonal and diel fish distributions within the cul-de-sac area relative to dam 

operations and the PFFC. 

• Estimate the seasonal and diel fish behavior and movements into and within the cul-de-sac area 

relative to dam operations and the PFFC. 

• Estimate the seasonal and diel metrics of fish passage at the temperature control tower.

• Estimate the seasonal and diel metrics of fish collection of the PFFC. 

In addition to these objectives, the U.S. Geological Survey (USGS) also was contracted to 

measure water velocities in the PFFC, and to summarize PFFC and Cougar Dam operations and PFFC 

fish collection data provided by the USACE. 

Methods

Dam Operations and Environmental Conditions

Powerhouse discharge, RO discharge, reservoir elevation, depth (head) over the water 

temperature control tower weir gates, and water temperature data were summarized to document the 

environmental conditions that juvenile Chinook salmon experienced from September 10, 2015, to April

28, 2016. Hourly powerhouse discharge, spill discharge, reservoir elevation, weir elevation, RO gate

openings, and PFFC operation data were provided by the USACE. Spill discharge consists of all 

discharge through the RO and the diversion tunnel. During the period when the diversion tunnel was in 

use, discharge was in excess of 2,600 ft3

/s for 37 hours from March 13 at 6 p.m. through March 15 at 7 

a.m.— the discharge data from the RO and diversion tunnel are recorded as “spill” so we cannot 

distinguish between the routes when they operated concurrently. In appendix A, we assumed that all 

spill discharge between March 3 at 1 p.m. and April 20 at 1 p.m. went through the diversion tunnel, and 

that all other spill discharge went through the RO. Hourly water temperature data were obtained from 

the USACE Web site http://www.nwd-wc.usace.army.mil/ftppub/water_quality/tempstrings/. Elevations 

of the temperature sensors on the Web site were corrected to NGVD 29 datum minus 2.831 ft between 

April 10, 2014 and December 9, 2015, in accordance with deployment. Elevations of the temperature 

sensors on the Web site were corrected to NGVD 29 datum minus 2.874 ft beginning on December 9, 

2015, when a new sensor was installed. Diel periods were assigned using U.S. Naval civil twilight time 

for Springfield, Oregon, and were obtained at http://aa.usno.navy.mil/data/docs/RS_OneYear.php. Data 

were summarized using the hourly observations, but mean daily values were plotted to increase clarity 

in the plots. Water elevation data are presented in feet and discharge is presented in cubic feet per 

second according to the local convention. 
7 

Operation and Hydraulic Indicators of PFFC Performance

Operating Conditions and Treatment Schedule

A randomized-block design based on two inflow treatments was used in 2015 and 2016. The 

treatments consisted of 95 percent of maximum speed of the attraction pumps, resulting in about 122 

ft3

/s inflow at the mouth of the PFFC (High) and 50-percent maximum speed of the attraction pumps, 

resulting in about 72 ft3/s inflow (Low; table 1). The treatment schedule prescribed 7-day treatments

within 14-day blocks, except when the pumps were turned off for trap catch evaluation or other 

intermittent outages. A 7-day treatment length was determined to provide sufficient data for analysis 

and a reasonable change interval for PFFC operators. The PFFC was off from June 17 to September 14, 

2015, to avoid handling fish during warm water temperatures and from March 1 to April 19, 2016, when 

the cul-de-sac was drained for debris removal at the water temperature control tower. 

Operating condition data for the PFFC were provided by the USACE from March 2, 2015, 

through March 1, 2016. The PFFC operation data include treatment blocks 1–24 (May 27, 2015–

February 1, 2016). The PFFC was operated at the High treatment during February and then shut off and 

moved out of the cul-de-sac. The PFFC operation data were independently entered by USGS and 

USACE employees, compared, and reconciled. 

Table 1. Planned portable floating fish collector (PFFC) operations, Cougar Reservoir and Dam, Oregon, 2015–

2016. 

[The Low treatment was an inflow of about 72 cubic feet per second (ft3

/s) and the High treatment was an inflow of about 

122 ft3

/s] 

Block Treatment Start End

1 High 03/02/2015 03/09/2015

Low 03/09/2015 03/16/2015

2 High 03/16/2015 03/23/2015

Low 03/23/2015 03/30/2015

3 Low 03/30/2015 04/06/2015

High 04/06/2015 04/13/2015

4 Low 04/13/2015 04/20/2015

High 04/20/2015 04/27/2015

5 Low 04/27/2015 05/04/2015

High 05/04/2015 05/11/2015

6 Low 05/11/2015 05/18/2015

High 05/18/2015 05/25/2015

7 Low 05/25/2015 06/01/2015

High 06/01/2015 06/08/2015

8 Low 06/08/2015 06/15/2015

High 06/15/2015 06/22/2015

9 High 06/22/2015 06/29/2015

Low 06/29/2015 07/06/2015

10 High 070/6/2015 07/13/2015

Low 07/13/2015 07/20/2015
8 

Block Treatment Start End

11 Low 07/20/2015 07/27/2015

High 07/27/2015 08/03/2015

12 High 08/03/2015 08/10/2015

Low 08/10/2015 08/17/2015

13 High 08/17/2015 08/24/2015

Low 08/24/2015 08/31/2015

14 Low 8/31/2015 09/07/2015

High 09/07/2015 09/14/2015

15 High 09/14/2015 09/21/2015

Low 09/21/2015 09/28/2015

16 High 09/28/2015 10/05/2015

Low 10/05/2015 10/12/2015

17 High 10/12/2015 10/19/2015

Low 10/19/2015 10/26/2015

18 Low 10/26/2015 11/02/2015

High 11/02/2015 11/09/2015

19 Low 11/09/2015 11/16/2015

High 11/16/2015 11/23/2015

20 High 11/23/2015 11/30/2015

Low 11/30/2015 12/07/2015

21 High 12/07/2015 12/14/2015

Low 12/14/2015 12/21/2015

22 High 12/21/2015 12/28/2015

Low 12/28/2015 01/04/2016

23 Low 01/04/2016 01/11/2016

High 01/11/2016 01/18/2016

24 Low 01/18/2016 01/25/2016

High 01/25/2016 02/01/2016

25 Low 02/01/2016 02/08/2016

High 02/08/2016 02/15/2016

26 High 02/15/2016 02/22/2016

Low 02/22/2016 02/29/2016

27 Low 02/29/2016 03/07/2016

High 03/07/2016 03/14/2016

28 High 03/14/2016 03/21/2016

Low 03/21/2016 03/28/2016

29 High 03/28/2016 04/04/2016

Low 04/04/2016 04/11/2016

30 High 04/11/2016 04/18/2016

Low 04/18/2016 04/25/2016
9 

Water Velocities

A SonTek® Acoustic Doppler Velocimeter (ADV; San Diego, California) was used to measure 

hydraulic conditions under two operating conditions within and at the opening of the flume at the PFFC. 

Interpolation between point samples was used to create three-dimensional-flooded representations of 

velocity magnitude and point vector direction of flow for the volume sampled using Tecplot 

360TMsoftware (Bellevue, Washington). Hydraulic profiles of velocity, gradient, and acceleration were 

calculated using methods consistent with Sweeney and others (2007). 

PIT Interrogator

A single passive integrated transponder (PIT) antenna was installed during PFFC construction. 

The antenna was near the knife gate approximately 6 m inside the opening of the PFFC and was

controlled with an IS1001 MTS controller (Biomark®, Boise, Idaho). The MTS controller was 

configured to produce hourly noise and status reports and transmit virtual test signals (an electronic tag 

signal sent from the controller to the antenna). Information from the PIT-tag interrogator was manually 

downloaded and detection data were uploaded into the PTAGIS database (www.ptagis.org) using the 

site code CGJ. Evaluation of the detection probability of the interrogator is summarized in appendix B. 

Fish Collection by the PFFC

The collection of fish by the PFFC was monitored on-site by USACE staff Monday through 

Saturday. The collection data included fish collection from March 2, 2015, to March 1, 2016. The data 

provided were independently entered by USGS and USACE employees, compared, and reconciled. 

Species in the PFFC trap catch were identified by USACE staff. Juvenile Chinook salmon were 

assigned to year classes based on the relative growth characteristics for Cougar Reservoir identified in 

Monzyk and others (2012). The collected fish were attributed to the PFFC treatment in operation at the

time of handling; however, some fish were found in holding cells during trap maintenance and may 

have been collected in a different PFFC treatment. Data from 1,833 juvenile Chinook salmon were 

collected without size measurements, but were identified by the USACE staff as 1,824 subyearlings and 

9 yearlings. These fish were not included in the fork-length analysis but were included in the mortality 

summary. 

We calculated the catch per unit effort (CPUE) as the number of juvenile Chinook salmon 

collected over the total hours of trap operation in each treatment within each block, and standardized the 

CPUE to fish per 24 hours of trap operation. We used two-way analysis of variance (ANOVA) to test 

for treatment and block effects on CPUE (version 9.4 of the SAS System for Microsoft Windows©

2002–2012, SAS Institute Inc., Cary, North Carolina). When an effect was significant, the TukeyKramer multiple-comparison test was applied to determine the source of differences between treatments 

and among blocks. An α = 0.05 was used for the tests. 

Acoustic- and PIT-Tag Telemetry

Transmitters

Fish implanted with acoustic tags also were implanted with a PIT tag. We used the juvenile 

salmon acoustic telemetry system (JSATS) for acoustic telemetry (McMichael and others, 2010). The 

model SS3300 JSATS tag was manufactured by Advanced Telemetry Systems (ATS; Isanti, Minnesota) 

and had a mean mass in air of 0.43 g (range 0.42–0.45 g). The dimensions were 11.74 mm long × 6.27 

mm wide × 3.64 mm deep. Expected transmitter life at the nominal pulse rate interval (PRI) of 10 
10 

seconds was 150 days. A 12.5-mm long full-duplex PIT tag (model SST, Biomark®, Boise, Idaho) 

weighing 0.10 g was placed inside the body cavity along with the acoustic transmitter. In February, 

June, and September, we injected PIT tags into 1,497 fish without an accompanying acoustic transmitter 

to evaluate PFFC collection rates. The lives of a subset of acoustic transmitters were empirically 

determined to define the follow-up time for analysis (appendix C). A follow-up time equal to the 90th 

percentile of tag life, 131.0 days, was subsequently used for analysis of data from acoustic-tagged fish. 

Handling, Tagging, and Release

Hatchery and wild-origin spring Chinook salmon (hereinafter referred to as hatchery Chinook 

salmon and wild Chinook salmon) comprised the tagged study population. Subyearling fish from each 

origin were released in the fall. The hatchery Chinook salmon were of broodstock year (BY) 2014 

(BY14) and implanted with acoustic and PIT tags (acoustic+PIT) in September and November. Yearling 

hatchery Chinook salmon (BY13) were released in March and sub-yearling hatchery fish (BY14) were 

released in June with PIT tags. The hatchery Chinook salmon were reared at the Fish Performance and 

Genetics Laboratory (FPGL) in Corvallis, Oregon, as part of a Wild Fish Surrogate Program funded by 

the USACE. The wild Chinook salmon were collected from the PFFC. 

Hatchery Chinook salmon were delivered and held at the McKenzie River Hatchery in Leaburg, 

Oregon, prior to acoustic+PIT-tagging. A total of 605 hatchery Chinook salmon were delivered on 

September 1, 2015, by FPGL employees to allow time for acclimation and an extended recovery time 

after transport. The fish were sorted by size prior to transportation to McKenzie River Hatchery to meet 

a fork-length requirement of 95–180 mm. Water temperature and dissolved oxygen in the transport tank 

were monitored during the transport period. Tempering was not required during transport from FPGL to 

the McKenzie River Hatchery, as the two water sources were within 2 °C of each other. All hatchery 

Chinook salmon were held in approximately one-half of an outdoor concrete raceway (total length 22.86 

m long × 5.1 wide × 0.8 m deep; 94,521 L in volume) supplied with continuously flowing McKenzie 

River water. The fish were held for 6–76 days prior to tagging. 

Hatchery and wild fish were treated in the same manner once they arrived at the tagging site and

differed only in the transport and length of their pre-tag holding time. The hatchery fish were moved 

from the McKenzie River Hatchery raceway, netted in a 264-L transport tank on six different occasions 

(September 8, September 21–23, and November 16–17, 2015) by USGS employees and transported to 

the tagging site at the Cougar Dam adult fish facility. Wild Chinook salmon were collected in the PFFC, 

sorted, and transported to the tagging site by USACE personnel; placed in 264-L holding tanks with 

flow-through water; and held until tagging occurred. Separate tanks were provided for each day of the 

week collection occurred at the PFFC. 

All fish were denied food once they were placed in the transport/holding tanks. Pre-tag holding 

times began once fish arrived and were placed in corresponding tanks at the tagging site. The hatchery 

Chinook salmon pre-tag holding times were within the 18–30 hour specification of the Surgical 

Protocols Steering Committee (2011). After receiving approval, the wild fish pre-tag holding times were 

extended past the maximum 30-hour holding period to increase the number of fish available to tag per 

effort. The wild fish were held 2–6 days, (mean 2.5 days) prior to tagging. 

Acoustic transmitters and PIT tags were surgically implanted using the protocol of the Surgical 

Protocols Steering Committee (2011). All tagging was performed by trained USGS employees. Both 

hatchery and wild Chinook salmon were considered suitable for tagging if they were free of major 

injuries; had no external signs of gas bubble trauma, major fin damage, or fungus; were less than 20-

percent descaled; had no visible signs of deformities or disease; and were not previously tagged other 

than with a coded-wire tag. Fish were not acoustic tagged if more than five copepods (Salmincola 

californiensis) were observed during macroscopic examination of the branchial cavities (Beeman and 
11 

others, 2015). Any wild fish not meeting the acoustic-tagging criteria was injected with a PIT tag and 

released downstream of Cougar Dam near the USGS streamgage (number 14159410). Fish were 

anesthetized using buffered tricane methanesulfonate (MS-222, Western Chemical Inc., Ferndale, 

Washington). The MS-222 concentration varied with fish origin and water temperature. The 

concentration range for hatchery fish was 100–110 mg/L whereas the concentration range for wild fish

was 80–90 mg/L. Weight and length of each anesthetized fish were recorded immediately prior to 

surgery. All weighing, measuring, and containment equipment were treated with a 0.25 mL/L 

concentration of Stress Coat Plus® (Aquarium Pharmaceuticals, Inc., Chalfont, Pennsylvania) to reduce 

handling related stress to the fish through electrolyte loss. Fish were placed in a 19-L perforated bucket 

filled with 7 L of river water immediately after surgery. Dissolved oxygen concentrations were 

maintained between 80 and 110 percent saturation during recovery. The mean density in a recovery 

bucket was 15.8 g/L (range 3.0–32.7 g/L) for hatchery Chinook salmon and 4.9 g/L (range 0.9–14.9 

g/L) for wild Chinook salmon. Water quality (water temperature, dissolved oxygen, and total dissolved 

gas) was monitored in holding buckets, transport tanks, the recovery raceway, and at release sites. Fish 

in recovery buckets were observed periodically during the first 10 minutes after surgery to ensure that 

they recovered from anesthesia. Recovery buckets, fitted with bicycle inner tubes near their tops for 

flotation, and a lid to secure the fish inside, were floated in an outdoor raceway with flowing river 

water. All tagged fish were held prior to release with access to air to adjust their buoyancy and fully 

recover post-surgery.

To encompass smaller fish sizes to better represent the entire run during the spring and fall, 

hatchery Chinook salmon with a minimum fork length of 65 mm were implanted with only a PIT tag to 

estimate PFFC collection efficiency. Hatchery Chinook salmon between 65 and 180 mm fork length 

were PIT tagged in February (n=505), June (n=508), and September (n=491). All PIT-tagging occurred 

in Corvallis, Oregon, at the FPGL. The PIT tags were the same model as those implanted with the 

acoustic transmitters. The first PIT-tag group (tagged in February) was held for 28 days and released on 

March 4, 2015, and the second group was held for 14 days in June and released on June 16, 2015. The 

third PIT-tag group was held 6 days and released on September 24, 2015. The PIT-tagged fish were 

treated in the same manner as the fish that were acoustic+PIT tagged in all aspects of handling, tagging, 

tempering, and releasing, following the Surgical Protocols Steering Committee (2011). All PIT-tagging 

was performed by trained USGS employees and followed procedures in PIT Tag Steering Committee 

(2014). Tempering was done using the same procedures by FPGL employees when they transported fish 

to the hatchery. When water temperatures differed by more than 2 °C at the release site, additional 

tempering was performed. 

Fish handling and release procedures were designed to minimize fish stress and maintain water 

quality. Fish implanted with an acoustic transmitter were released near the head of Cougar Reservoir 

after the 18–36 hour recovery period specified by the Surgical Protocols Steering Committee (2011). 

Recovery buckets were removed from the holding raceway, inspected for mortalities, and transferred to 

one of two insulated 1,556-L plastic tanks mounted on a flatbed trailer. The fish were then driven to the 

boat ramp, transferred to a boat, and transported upstream through Cougar Reservoir about 7 river 

kilometers (rkm) to the release site. The release site was about halfway between the two shorelines near 

the Slide Creek boat ramp (fig. 5). Hatchery and wild fish were released by partially submerging and 

gently inverting their holding bucket in the reservoir. 
12 

Hatchery and wild fish PIT-tagged were transported to their respective release sites. The three 

groups of hatchery fish (March, June, September) were netted at FPGL and placed in an aerated 

transport tank filled with fresh river water. Fish were transported upstream of Cougar Reservoir 

approximately 2 rkm from the Slide Creek boat ramp and released from the river bank. Water quality 

measurements were taken periodically, and were recorded throughout transport and again at the release 

site to verify if tempering was needed. Wild Chinook salmon collected by the PFFC that did not meet 

the acoustic+PIT criteria were injected with a PIT tag, allowed ample time to recover, and released 

downstream of the Cougar Dam tailrace near the USGS streamgage. 

Figure 5. Orthoimage showing arrays of autonomous hydrophones (small circles) deployed in Cougar Reservoir, 

Oregon, 2015–2016. The acoustic+PIT release location is indicated with an arrow and the PIT release location is 

approximately 2 river kilometers upstream of that site on the right side of the image.

Acoustic Telemetry Detection System

Signals from acoustic transmitters were detected using two types of JSATS hydrophone systems 

provided by the USACE. Acoustic signals from tagged fish in the reservoir near the log boom at the 

boat-restricted zone and upstream near the head of the reservoir were detected using autonomous 

hydrophones spaced across the reservoir width at two locations (fig. 5). In 2011, we empirically 

determined in the eastern arm of Cougar Reservoir that 82 percent of the expected number of 

transmissions were detected at a range of 105 m, and 10 percent were detected at a range of 180 m. 

Based on that data, the hydrophones were spaced about 100 m from shorelines and 200 m from each 

other at a depth of about 33 m from the water surface along lines across the reservoir (hereinafter 

referred to as “arrays”). Hydrophones were deployed using methods similar to those described by 

Titzler and others (2010), except that burlap bags filled with sand as anchors were used. The 

autonomous hydrophones were operational prior to acoustic+PIT fish releases and were serviced at 2–3-

week intervals. 
13 

Nine 4-hydrophone cabled systems linked to each other using a common clock were used to 

detect acoustic signals from tagged fish near the tower and PFFC. Each of these systems included four 

hydrophones connected with cables to a common computer. Each computer received its system time 

from a Global Positioning System (GPS) receiver (Meinberg GPS 170PCI, Meinberg Funkuhren GmbH 

& Co. KG, Bad Pyrmont, Germany). The use of a common time for all hydrophones allows the 

estimation of fish position based on time of signal arrival if hydrophone locations and the speed of 

sound in the study area are known. A GPS was used to determine locations of hydrophones deployed 

from floating platforms. Javad (San Jose, California) Global Navigation Satellite System (GNSS®) 

Sigma receivers were used to collect positional data on hydrophones floating on anchored platforms in 

the forebay. The receivers were programmed to provide real-time kinematic positions every second. 

Dorne-Margolin choke ring antennas with Southern California Integrated GPS Network radomes were 

used to minimize multipath signals from surrounding concrete and rock structures to increase the quality 

of position solutions. This combination of equipment used GPS, GLONASS (Russian satellites), and 

Galileo satellites to compute positions within ±1 cm. The cabled hydrophone system is described by 

Weiland and others (2009, 2011). 

The cabled hydrophone systems were installed along the upstream face and inside of the 

temperature control tower at several elevations and from floating platforms (figs. 6 and 7). All 

hydrophones deployed from floating platforms were located 2.5 m below the water surface. Additional 

hydrophones were placed 16.5 m below the water surface at four locations near the entrance to the 

PFFC (fig. 7). All floating platforms around the PFFC were tied together and to the PFFC, and anchored 

such that the floating array moved with the PFFC as forebay elevation changed. The range of the cabled 

hydrophone systems was assumed to be similar to that of the autonomous hydrophones, so hydrophones 

were spaced with overlapping coverage. This assumption seemed reasonable because each transmitter 

signal typically was detected by most of the cabled hydrophones. 

To detect acoustic-tagged fish as they migrated through the South Fork McKenzie River, we 

deployed autonomous hydrophones at four locations downstream of Cougar Dam: (1) four hydrophones 

in the tailrace (two each in the powerhouse and RO tailraces); (2) one hydrophone about 0.4 rkm 

downstream of the dam near the confluence of both tailraces; (3) one hydrophone about 1.1 rkm 

downstream of the dam near USGS streamgage number 1415410; and (4) one hydrophone about 2.3 

rkm downstream of the dam. 
14 

Figure 6. Photographs showing locations of cabled hydrophones nearest the water temperature control tower at 

Cougar Dam, Oregon, 2015–16. Round symbols represent hydrophones affixed to the water temperature control 

tower, and square symbols indicate hydrophones mounted from floating platforms. Dotted lines represent 

approximate locations of full and minimum conservation pool water elevations of 1,690 and 1,532 feet, respectively. 

Photograph taken during construction in 2005 provided by U.S. Army Corps of Engineers, and inset photographs 

taken by Amy C. Hansen (upper photograph, May 17, 2011) and Scott D. Evans (February 2, 2011), U.S. 

Geological Survey.
15 

Figure 7. Photograph showing locations of hydrophones deployed 2.5 meters (m) below the water surface from 

floating platforms (small squares) near the portable floating fish collector (PFFC; center) and water temperature 

control tower (right) at Cougar Dam, Oregon, 2015–16. Four locations identified by arrows had an additional 

hydrophone 16.5 m below the water surface. Photograph by Scott D. Evans, U.S. Geological Survey, August 6, 

2015. 

Removing False-Positive Records

Data from the hydrophones were processed to remove false-positive records prior to analysis. 

False-positive records are those that indicate detection of a transmitter when the transmitter was not 

present, and are common in most active telemetry systems (Beeman and Perry, 2012). We used the 

procedures developed by Pacific Northwest National Laboratory (Mark Weiland, written commun., June 

17, 2010) to remove false-positive records. The steps include removing records from tag codes not 

released, records suspected of being from reflections of valid tag signals (multipath), and records that 

are not close to a multiple of the tag pulse interval (McMichael and others, 2010). Records from the

cabled hydrophone system also were required to be present on more than one hydrophone to be retained. 

Estimating Fish Positions

Fish positions within the area monitored by the cabled-hydrophone system near the dam were 

estimated using software developed through a USGS subcontract with the University of Washington 

(Seattle, Washington). The software estimates fish positions using an iterative technique using the 

Gauss-Newton method to find the location that minimizes the root-mean squared misfit to all available 

arrival-time data by repeatedly solving a set of linearized equations relating adjustments in location to 

changes in the arrival time misfit (Klein, 1978; Lee and Stewart, 1981; Menke, 1989; Speisberger and 

Fristrup, 1990). The software uses all available hydrophones and can adjust the speed of sound in water 

for vertical changes in water temperature using the method of Moser (1991). Water temperatures from 

the temperature string located near the temperature control tower were used for this purpose. 
16 

Fish position estimates were passed through a filter to identify and remove spurious results. The 

filter limited swim speeds to a burst speed of as much as 3 m/s for 20 seconds, or a sustained speed of as 

much as 1.0 m/s for more than 20 seconds based on values from the literature (Bainbridge, 1960; Webb, 

1978; Taylor and McPhail, 1985; Mesa and others, 2008). The first observation of each trip into the 

monitored area was omitted because of the lack of data to estimate swim speed, and a new trip was 

assigned if the time elapsed between successive positions was greater than the 99th percentile (273 

seconds). The filter identified 3.6 percent of the estimated positions. 

Travel Times

Analyses of the timing of downstream movement in the reservoir and tower passage or PFFC

collection were conducted using time-to-event methods (Hosmer and Lemeshow, 1999). The time 

elapsed from fish release to two event types was described using Kaplan-Meier survivorship functions. 

The event types were (1) detection by any autonomous hydrophone receiver near the log boom, and (2) 

detection within 10 m and at a depth of 0–6 m from the entrance to either the PFFC or tower. Fish that 

passed the dam or had not experience an event by the 90th percentile of the empirically determined 

transmitter life were right censored at that time. 

Depths in the Cul-de-Sac

Depths of fish were determined for acoustic+PIT-tagged fish from first arrival in the cul-de-sac 

to the 90th percentile of each tag life, during all hours and PFFC operations. Data from the 4 days 

between the first release and when the PFFC began operating on September 14 were omitted. The mean 

hourly depths were calculated from the median hourly depths of each fish.

Temperature Selection

A standardized resource selection index was estimated to determine if water temperatures were 

preferentially selected by acoustic+PIT-tagged fish within 20 m of the PFFC entrance or within 20 m of 

the tower entrance. We used the method of Manley and others (1993) as described by Rettie and 

Messier (2000) with water temperature as the available habitat and the water temperature at the fish 

depths as the habitat selected. Water temperature data from the string at the tower and fish depths from 

the acoustic telemetry system were used to estimate the index. A monthly index was estimated for each 

integer value of water temperature at depths within the 99th percentile of the daily maximum fish depth 

(the habitat available) based on the water temperatures at the mean of the median daily depths of each 

fish (the habitat selected). The proportion of fish is the habitat selected divided by the habitat available 

by month. The sum of the monthly standardized resource selection index within an individual month is 

1. 

Spatial Intensity of Use

Fish distributions relative to the PFFC location and operating conditions were estimated spatially 

and temporally. Fish positions estimated using the acoustic telemetry array in the cul-de-sac were used 

to estimate utilization distributions (UDs) using the dynamic Brownian Bridge Movement Model 

(dBBMM) of Kranstauber and others (2012). The dBBMM uses spatial and temporal information from 

a series of positions as well as the position-specific location estimation errors to estimate the UD as a 

probability of use among cells of a raster, where UD values in the raster sum to 1. Location estimation 

errors in the monitored area were empirically determined for this purpose and are described in appendix 

D. Data were prepared for use in the model by grouping positions from each tagged fish into quasiindependent trips (bursts) separated by gaps of at least 30 minutes using the adehabitatLT package for R 
17 

software (R Core Team, 2014). The UDs were estimated using the Move package for R software with 

model parameters of a 5 × 5 m raster cell size, an extent of 0.7, a window size of 9, a margin of 3, and a 

time step of 1(Kranstauber and Smolla, 2016). The window and margin sizes control the boundaries of a 

moving window used in estimating the UD and the time step controls the size of the time intervals (in 

minutes) taken for each integration step. We used the smallest window and margin settings allowable 

due to the small spatial area of the cul-de-sac and high frequency of positions based on the 10-second

PRI of the tags; this resulted in a minimum burst of 9 positions for inclusion in the analysis (an alternate 

method is described in the next paragraph). Location errors were based on data from stationary and 

moving test tags interpolated to the fish positions using the Kriging process (see appendix D for 

estimates of positioning system accuracy). We estimated UDs for data divided into operational strata 

(Low and High treatments), environmental strata (months of September to January inclusive; day or 

night defined using civil twilight times), and biological strata (five 3-m fish depth bins from the water 

surface to 15 m deep). The UD for each stratum was calculated by averaging UDs among bursts within 

each fish and then averaging UDs among fish. The total number of cells within each raster varied based 

on the extent of the data in each stratum, but generally was about 9,000. 

Overlap of UDs between strata was estimated using the utilization distribution overlap index 

(UDOI) after projecting the spatial extent of the smaller UD of each pair to that of the larger. The UDOI 

assesses spatial overlap based on the product of two UDs and generally ranges from 0 to 1 to indicate 

increasing overlap (Fieberg and Kochanny, 2005). The spatial extent of the UDs was values of UDOI 

greater than 1 can arise during conditions of overlapping UDs with non-uniform distributions, but the 

UDOI generally performs better than other indices of overlap (Robert and others, 2012). 

Fish use within 20 m of the PFFC entrance was not estimated using the dBBMM because of the 

limited sample size and the short burst lengths near the PFFC entrance. For that area, we estimated the 

spatial fish use by calculating the percentage of the positions from each burst within each of 60 4 × 4 m 

cells of a raster and averaging in the same manner as with the UDs for the cul-de-sac. This method has 

the advantage over the dBBMM of not restricting the data available by the number of positions within a 

burst, but does not include advantages of the dBBMM such as incorporating position estimation errors; 

however, the estimation error varied little over this small area (appendix D). 

Movement Behaviors

In the Cul-de-Sac

We examined fish swimming behavior in different areas of the cul-de-sac by estimating the 

tortuosity of fish tracks using the straight line index (Batschelet, 1981). Tortuosity is the degree of 

turning or meandering in a fish track compared to the degree of straightness. The straight line index 

measures the departure of a fish’s actual movement path from that of a Euclidean straight line between 

the beginning and ending points of a particular movement track and is calculated by dividing the 

Euclidean distance between these two points by the total length of the track. The estimated values of the 

index range from 0 to 1 and are inversely related to the degree of tortuousness. Therefore, as values of 

the index approach 0, the movement paths become increasingly more tortuous, whereas values 

approaching 1 indicate increasingly more straight paths. 
18 

For our application, the sequential positions for each fish were divided into trips (bursts) as 

described in the spatial analysis (section, “Spatial Intensity of Use”), except that a new trip was initiated 

whenever the gap between two consecutive positions was greater than 5 minutes instead of 30 minutes. 

Each position within a burst was assigned to 1 of 255, 20 × 20 m, cells in the cul-de-sac. Tortuosities 

were estimated for each combination of the High and Low treatments, day and night, and two fish depth 

bins (0–3 and 3–6 m from the surface). The median cell tortuosity for each stratum was calculated as the 

median tortuosity among bursts within each fish and then the median tortuosity among all fish in a cell. 

These data were plotted in color-coded plots and visually examined for trends in movement behavior 

within the cul-de-sac area. 

Near the PFFC Entrance

The bearings (directions) of individual fish trajectories within 10 m of the PFFC entrance were 

used to further characterize the movement behavior of tagged fish near the collector during each 

treatment. The sequential positions from each fish were divided into trips (bursts) as described in the 

section Movement Behaviors: In the Cul-de-Sac. Each position in a burst was assigned to 1 of 10 4 × 5 

m cells in front of the PFFC and the bearing to the next location in the burst was calculated. Bearings 

were transformed so that a bearing of 0 degrees was oriented perpendicular to the collector. Mean 

bearings were estimated for each cell within a burst and then averaged among bursts using second-order 

circular analysis methods (Zar, 1999). The mean bearings for all fish positioned in a cell were displayed 

as a scatter of points on the circumference of a circle and then overlaid with a rose diagram with 24 

sectors so they could be examined visually for trends. The nonparametric second-order Moore test was 

used to test whether the mean bearings in each plot came from a population of uniformly (randomly) 

distributed bearings, or alternatively, that the means were from a population in which the bearings were 

not randomly distributed (Zar, 1999). The Moore test was considered significant when P<0.05. 

Collection in the PFFC and Dam Passage

Passage of acoustic+PIT-tagged fish through the water temperature control tower and collection 

in the PFFC was determined using presence data from the cabled hydrophones nearest the outlets at 

Cougar Dam and downstream data downloaded from PTAGIS. The date and time of assumed dam 

passage were assigned if the first detection of the last transmitted message was at any of the 

hydrophones located closest to the water outlets. This method was selected to limit passage assignments 

to fish last detected in the area generally in the cul-de-sac, and was consistent with histories of tagged 

fish known to have passed the dam based on detections of PIT tags downstream. We estimated several 

general fish passage metrics (table 2). Ninety-five-percent confidence intervals were calculated for these 

metrics using the Wald method. 
19 

Table 2. Passage and fish collection efficiency definitions. 

[Routes include PFFC and tower. "Number" refers to number of tagged fish. PFFC, portable floating fish collector; ft3

/s, 

cubic foot per second; m, meter]

Metric Acronym Definition

Reservoir passage efficiency RPE Number detected at log boom ÷ number released

Forebay passage efficiency FBE Number detected in cul-de-sac ÷ number detected at log boom

Dam passage efficiency DPE Number passing (Tower + PFFC) ÷ number detected at log boom

Discovery efficiency DE Number positioned within 10 m from route at 0–6 m deep ÷ 

number positioned in cul-de-sac

Entrance efficiency EE Number collected by route ÷ number positioned within 10 m 

from route at 0–6 m deep

Fish collection efficiency FCEFB Number collected by route ÷ number detected at log boom

Fish collection efficiency FCECDS Number collected by route ÷ number detected in cul-de-sac

Fish collection effectiveness FCF Fish collection efficiency ÷ PFFC inflow normalized to 100 ft3/s

Results

PFFC Operation and Data Collection Periods

Schedules for PFFC operation and installation of biological monitoring systems determined the 

periods available for analysis. The randomized-block treatment schedule of PFFC operations began on 

March 2, 2015, and ended on March 1, 2016 (table 3). Data from the three primary sources of biological 

data—the PFFC collection, the acoustic+PIT-tagged fish, and the PIT-tagged fish—were available for 

different periods based on the installation dates; however, data from at least one of the systems was 

available from March 2, 2015, to April 23, 2016. 

Table 3. Study periods based on operating conditions and data collection methods at Cougar Dam and Reservoir, 

Oregon, 2015–16. 

[PFFC, portable floating fish collector; JSATS, juvenile salmon acoustic telemetry system; PIT, passive integrated 

transponder]

Category Dates

PFFC operations March 2, 2015–March 1, 2016

JSATS releases September 10–November 19, 2015

JSATS presence monitoring September 10, 2015–April 23, 2016

JSATS positions in cul-de-sac September 10, 2015–January 26, 2016

JSATS tag life for analysis September 10, 2015–March 23, 2016

PIT releases and monitoring March 4, 2015–April 23, 2016
20 

Dam Operations and Environmental Conditions

The dry and warm weather during 2015 resulted in reservoir conditions unlike those of the 

recent past. Water temperatures were higher, reaching a maximum of 23.8 °C in the upper 13–19 ft on 

July 4, 2015 (figs. 8, 9). Additionally, the reservoir was not filled, reaching a peak elevation of 1604.2 ft 

on June 7, 2015 prior to receding on June 12, 2015. Reservoir drawdown was initiated on March 3, 

2016, by opening the diversion tunnel near Rush Island. The reservoir elevation steadily decreased to an 

elevation of 1,456.0 ft on March 28, 2016, and began filling on March 31, 2016, through our study 

period ending on April 23, 2016, when the elevation was 1,532.75 ft. Discharge through the dam was 

less than 500 ft3/s from mid-February through late-November and then increased multiple times during 

December–April and peaked at 3,160 ft3

/s on December 23, 2015, at 9 a.m. (appendix A). The 

powerhouse operated through December 16 at 2 p.m. at a mean of 353.3 ft3/s (range 0.0–840.0 ft3/s) and 

was similar between day and night. After December 16, the powerhouse was off for trash rack repair 

and debris removal until April 20, 2016. Throughout the entire JSATS study period, mean powerhouse 

discharge was 157.1 ft3

/s (range 0.0–1,280.0 ft3/s; appendix A). The RO operated intermittently until 

November 19, 2015, when it operated continuously until the diversion tunnel was opened between 

March 3 at 1 p.m. and April 20 at 1 p.m., 2016. Once the diversion tunnel was opened, the RO was off 

except when discharge exceeded the maximum capacity of the diversion tunnel, which was 2,600 ft3

/s at 

an elevation of 1,511 ft. Capacity of the diversion tunnel changed gradually as the water elevation 

decreased (Tina Teed, USACE, written commun., March 30, 2016). Mean spill discharge during the 

period when the diversion tunnel was operated was 1,402.3 ft3/s (range 0.0–2,970.0 ft3/s), and was 

higher during the night than during the day (appendix A). The diversion tunnel was closed for 4 hours 

on April 18, 2016, during powerhouse testing. During periods when the diversion tunnel was not 

operating, mean spill discharge through the RO was 873.4 ft3/s (range 0.0–3,160.0 ft3/s), and was 

slightly higher at night. Temperature control regulated by the nine weir gates occurred until September

28, 2015, when the gates were returned to the top of the tower. Hourly head over the weir gates ranged 

from 8.2 to 42.2 ft during the study period when in use. 
21 

Figure 8. Graphs of mean daily project discharge and head over the weir gates (top), and reservoir elevation and 

water temperature (bottom) at Cougar Reservoir, Oregon, January 1, 2015–April 23, 2016. Water temperature is 

the average of the upper 13–19 feet of the water column near the temperature control tower. Additionally, the 

bottom graph shows daily passage of juvenile Chinook salmon through the water temperature control tower and 

portable floating fish collector (PFFC) as a percentage of tagged fish in the reservoir available to pass (vertical 

bars). 
22 

Figure 9. Contour plot of hourly temperature in degrees Celsius by water depth of sensors in the Cougar 

Reservoir, Oregon, March 1, 2015–March 1, 2016. 

Operation and Hydraulic Indicators of PFFC Performance

Operating Conditions and Treatment Schedule

The two-treatment block schedule was adhered to with the following exceptions (table 4). High 

treatment used a setting of 95 percent (of maximum speed of the attraction pumps) and Low treatment 

used a setting of 50 percent. The trap was off when crews performed maintenance, worked up the 

collected animals, changed the treatment, or during power outages. The High treatment in blocks 6 and 

23 were extended by 1 day and the Low treatments in blocks 7 and 24 were reduced by 1 day. Similarly, 

the Low treatment in block 16 was extended by 2 days and the High treatment in block 17 was reduced 

by 2 days. The PFFC temporarily was off because of power outages during blocks 5 (50.4 hours), 6 

(51.7 hours), and 21 (27.0 hours), and between blocks 21 and 22 (28.1 hours). The last treatment block 

ended on February 1, 2016 (block 24) and the PFFC was operated at the High setting until March 1, 

2016, when it was turned off for trash rack maintenance. The PFFC was off from June 17, 2015 at 9:25 

a.m. to September 14, 2015 at 1:33 p.m. to avoid handling fish during warm water temperatures, and 

from March 1 to April 19, 2016, when the cul-de-sac was drained for debris removal at the water 

temperature control tower. 

Pump configuration, distance from the tower, mean observed reservoir elevation, and water 

quality (water temperature and dissolved oxygen) when the USACE crew worked at the PFFC are 

shown in appendix E. Flow into the water temperature control tower was included in the appendix table. 
23 

Table 4. Actual portable floating fish collector (PFFC) operations at Cougar Reservoir, Oregon, during the 

randomized-block treatment schedule, 2015–16. 

[Periods when the portable floating fish collector was off for sampling or maintenance during a treatment period were 

omitted in the duration estimates. NA, not applicable] 

Block Treatment Start End

Treatment

duration

(days)

1 High 03/02/2015 16:00 03/09/2015 12:06 6.28

Low 03/09/2015 13:45 03/16/2015 11:06 6.79

2 High 03/16/2015 14:27 03/23/2015 11:30 6.58

Low 03/23/2015 12:31 03/30/2015 12:19 6.67

3 Low 03/30/2015 13:23 04/06/2015 12:50 6.80

High 04/06/2015 14:10 04/13/2015 10:05 6.43

4 Low 04/13/2015 11:50 04/20/2015 11:35 6.72

High 04/20/2015 12:40 04/27/2015 11:18 6.67

5 Low 04/27/2015 13:27 05/04/2015 13:00 6.78

High 05/04/2015 14:38 05/11/2015 09:45 4.58

6 Low 05/13/2015 12:24 05/18/2015 11:05 4.72

High 05/18/2015 12:54 05/26/2015 12:28 7.51

7 Low 05/26/2015 14:02 06/01/2015 11:23 5.75

8 Low 06/11/2015 15:17 06/17/2015 09:25 5.66

15 High 09/14/2015 13:33 09/21/2015 12:25 6.82

Low 09/21/2015 13:22 09/28/2015 12:14 6.73

16 High 09/28/2015 13:22 10/05/2015 13:00 6.66

Low 10/05/2015 14:16 10/14/2015 12:43 7.78

17 High 10/14/2015 13:25 10/19/2015 12:42 4.86

Low 10/19/2015 13:10 10/26/2015 10:27 6.73

18 Low 10/26/2015 11:03 11/02/2015 12:44 6.88

High 11/02/2015 13:58 11/09/2015 13:44 6.79

19 Low 11/09/2015 14:18 11/16/2015 12:13 6.63

High 11/16/2015 12:58 11/23/2015 10:30 6.38

20 High 11/23/2015 12:36 11/30/2015 11:20 6.63

Low 11/30/2015 11:31 12/07/2015 11:30 6.90

21 High 12/07/2015 14:15 12/14/2015 10:54 5.53

Low 12/14/2015 14:19 12/21/2015 11:36 5.74

22 High 12/22/2015 15:40 12/28/2015 12:38 5.75

Low 12/28/2015 14:00 01/04/2016 12:45 6.77

23 Low 01/04/2016 13:51 01/11/2016 12:33 5.76

High 01/11/2016 13:33 01/19/2016 12:14 7.54

24 Low 01/19/2016 13:14 01/25/2016 13:12 5.87

High 01/25/2016 13:52 02/01/2016 12:16 6.59

NA High 02/01/2016 14:06 03/01/2016 11:37 28.90
24 

Water Velocities

Low suspended backscattering material resulted in a degraded signal-to-noise ratio and lower

correlation values than desirable, reducing sample sizes and confidence in the data more than expected. 

Many samples did not meet the filter requirement and some points were completely removed by 

filtering. Despite lower sample sizes (less than 650 in 2015 compared to more than 1,700 in 2014), the 

results were consistent with data collected by HDR Engineering, Inc. during recommissioning of the 

PFFC in February 2015 (HDR Engineering, Inc., 2015; fig. 10). 

Figure 10. Graph of 2015 velocity measurements during HDR Engineering, Inc. (HDR) recommissioning and 

USGS sampling in the flume of the portable floating fish collector (PFFC) at Cougar Reservoir, Oregon, February 

2015 (AT=attraction pump flow, BP=bypass flow, CP=constrictor panel opening). HDR measured sweeping 

velocity, USGS measured velocity of cross-sectional areas. HDR data from HDR Engineering, Inc. (2015).

Within the flume, the velocity magnitude increased by 0.5–1.0 ft/s from 2014 to 2015 postmodification depending on location in the flume. The hydraulic profiles during the Low treatment 

remained relatively consistent for velocity, gradient, and acceleration although with slightly larger 

magnitudes. The High treatment profiles changes reflected the Low treatment profiles, but at generally 

greater magnitude. Furthermore, the modification appears to have nearly eliminated the negative values 

of gradient and acceleration measured in the 2014 High treatment (fig. 11). 
25 

Figure 11. Hydraulic profile graphs of velocity magnitude, gradient, and acceleration for distance from the portable 

floating fish collector (PFFC) opening (positive distance is inside the flume) at Cougar Reservoir, Oregon, 2014–15. 

Red triangles represent the High treatment and black circles represent the Low treatment. 

The velocity magnitude inside the PFFC flume increased consistently over distance from the 

inlet. The velocity outside the PFFC flume decreased rapidly with distance from the PFFC entrance, 

particularly in the Low treatment. During the High treatment, the velocity is higher at the opening 

suggesting a potentially larger effect on the surrounding flow field (fig. 12).
26 

Figure 12. Three-dimensional view of sampled points (A = Low treatment, C = High treatment) and interpolated 

velocity magnitude in feet per second (B = Low treatment, D = High treatment) in the portable floating fish collector

(PFFC) at Cougar Reservoir, Oregon, 2014–15.
27 

Fish Collection by the PFFC

Collection by the PFFC varied by species and time from March 2, 2015, through March 1, 

2016.The trap was not operated from June 17 through September 13 because of restrictions in fish 

handling authority owing to high water temperatures. Juvenile Chinook salmon collected by the PFFC 

were predominately subyearling age class fish (fig. 13). Most fish collection occurred from March 

through June and was dominated by juvenile Chinook salmon. Bycatch consisted primarily of cyprinid 

(speckled dace [Rhinichthys osculus] and longnose dace [R. cataractae]), secondarily of centrarchids 

(bluegill [Lepomis macrochirus] and largemouth bass [Micropterus salmoides]), and additionally trout 

(adult bull trout [Salvelinus confluentus], rainbow trout [O. mykiss], and cutthroat trout [O. clarkii]) and 

a small number of other species (rough-skinned newt [Taricha granulosa], crayfish) (fig. 14). The total 

catch of Chinook salmon was 2,616 subyearlings, 258 yearlings, and one adult. Total catch of juvenile 

Chinook salmon by treatment was 1,035 during the Low treatment (ranging from 1 to 401 by block) and 

1,839 during the High treatment (ranging from 2 to 577 by block). 

Salmonid catch in the PFFC was higher in 2015 than in 2014 when comparing similar 

operational periods. In both years, the PFFC was operated from May 28 to June 16 and from September 

14 to December 16. Nearly three times as many subyearling Chinook salmon were collected in 2015 

compared to 2014 (365 and 125, respectively). A total of four yearling Chinook salmon in 2014 and 43 

in 2015 were collected during the common study dates. 

The CPUE of juvenile Chinook salmon ranged from 0.25 to 88.17 per 24 hours among the 

treatment and block combinations while the PFFC was operational. However, high mean CPUE was

accompanied by high standard error for those blocks and treatments (fig. 15). Differences in CPUE by 

blocks and treatments had varying levels of significance dependent on season. During blocks 1 through 

6, treatment was not significant (P=0.0828) at the 0.05 level. Differences between block was significant 

(P<0.0001) for blocks 1–6. Blocks 2, 3, and 4 were significantly higher than blocks 1, 5, and 6 (P< 

s0.006). For blocks 15–24, the High treatment was significantly different (P<0.0001) from the Low 

treatment and there also was some significance (P=0.0002) for block differences. Block 22 was

significantly lower than blocks 18, 19, and 20 (P=0.0014, 0.0046 and 0.0031, respectively). 

Figure 13. Graph of fork lengths of juvenile Chinook salmon collected at the portable floating fish collector (PFFC), 

Cougar Reservoir, Oregon, 2015–16. 
28 

Figure 14. Graphs showing frequency of juvenile Chinook salmon (top) and bycatch (bottom) captured by block 

and treatment at the portable floating fish collector (PFFC), Cougar Reservoir, Oregon, 2015–16. Note the 

difference in the y-axis scales. The PFFC was not operational for blocks 9–14 because of high water temperatures.
29 

Figure 15. Graphs of juvenile Chinook salmon mean catch per unit effort (CPUE) per 24 hours of trap operation by 

block and treatment at the portable floating fish collector (PFFC), Cougar Reservoir, Oregon, 2015–16. Whiskers 

represent the standard error. The PFFC was not operated during blocks 9–14 because of high water temperatures.

The mortality of juvenile Chinook salmon collected by the PFFC varied by age class and 

treatment. Mortality of subyearling Chinook salmon was relatively similar between treatments and 

combined (9.1–11.0 percent, table 5). Trap mortality accounted for most of the mortality (8.3–9.8 

percent) relative to handling mortality for the 2,616 subyearling Chinook salmon collected (table 5). For 

the 258 yearling Chinook salmon collected, trap mortality during the Low treatment was 4.5 times 

higher than during the High treatment. Handling mortality was a relatively small component of the 

overall mortality (table 5).

Table 5. Summary of mortality of juvenile Chinook salmon collected in the portable floating fish collector (PFFC), 

Cougar Reservoir, Oregon, March 2, 2015–March 1, 2016. 

[Morality is divided into Trap (dead upon examination of collection) and Handling (died between time of examination and 

release). N, number of fish]

Treatment Total

collected

Mortality

Trap Handling Total

N dead Percent N dead Percent N dead Percent

Subyearling Chinook salmon

Low 968 80 8.3 8 0.8 88 9.1

High 1,648 161 9.8 21 1.3 182 11.0

Combined 2,616 241 9.2 29 1.1 270 10.3

Yearling Chinook salmon

Low 67 8 11.9 0 0.0 8 11.9

High 191 5 2.6 2 1.0 7 3.7

Combined 258 13 5.0 2 0.8 15 5.8
30 

Handling, Tagging, and Release

During September–November, 2 wild Chinook salmon collected by the PFFC and 532 hatchery 

Chinook salmon were implanted with acoustic+PIT tags and released. Data from all tagged fish were 

grouped together for analysis. Hatchery fish were tagged and released during September 10–25 and 

November 18–19, 2015. A total of 23 wild Chinook salmon were collected and transported to the USGS 

tagging site. On October 1 and 7, 2015, one wild fish on each day that met the JSATS tagging criteria 

was collected in the PFFC. These two fish were implanted with an acoustic+PIT tag on October 5 and 

13, 2015, respectively, and released the following day. Eight of the 23 wild fish did not meet the 

surgical criteria and were injected with a PIT tag and released at the USGS streamgage downstream of 

Cougar Dam. Of the remaining 13 wild fish, 2 were acoustic+PIT-tagged and died, 3 were PIT-tagged 

and died, and 8 died in the pre-tag holding period. The mean fork lengths were 135.3 mm (range 99–180 

mm) for the hatchery fish and 129.5 mm (range 124–135 mm) for the wild fish (table 6). The mean tagweight-to-body weight ratio (based on the 0.53 g weight of the acoustic transmitter plus the PIT tag)

was 2.3 percent for the hatchery fish (range 0.8 to 5.5 percent) and 2.4 percent (range 2.2 to 2.6 percent) 

for the wild fish. Pre-tag holding times were within the 18–30-hour specification of the Surgical 

Protocols Steering Committee (2011) for the hatchery Chinook salmon, but not for the wild Chinook 

salmon. The pre-tag holding times ranged from 18.0 to 19.5 hours for the hatchery fish and 18.7 to 79.9 

hours for the wild fish. Wild fish were held longer in order to increase the sample size as tagging only 

occurred 3 days per week. Post-tag holding times were within the 18–36-hour specification of the 

Surgical Protocols Steering Committee (2011) for both hatchery (range 20.2–24.0 hours) and wild 

Chinook salmon (range 18.6–22.4 hours). 

Table 6. Summary statistics of fork length and weight of acoustic and passive integrated transponder (PIT) tagged 

hatchery and wild juvenile Chinook salmon at Cougar Reservoir, Oregon, 2015. . 

[The wild fish were PIT-tagged and released at the USGS streamgage (number 14159410) downstream of Cougar Dam. N, 

number of fish; SD, standard deviation] 

Fish origin Tag type N Fork length (millimeters) Weight (grams)

Mean SD Range Mean SD Range

March

Hatchery PIT 503 133.5 16.6 80–175 29.9 10.2 5.8–59.5

June

Hatchery PIT 505 81.1 9.8 65–110 6.4 2.5 2.8–14.0

September–November

Hatchery Acoustic+PIT 532 135.3 19.0 99–180 28.9 13.5 9.6–67.3

Hatchery PIT 489 114.8 13.7 70–145 19.1 6.1 4.2–45.6

Wild Acoustic+PIT 2 129.5 7.8 124–135 22.6 2.8 20.6–24.5

Wild PIT 8 128.5 36.4 91–201 23.5 17.9 7.8–62.0
31 

In addition to the acoustic+PIT-tagging, hatchery fish also were held and PIT-tagged at FPGL.

In March and June, 503 and 505 sub-yearling Chinook salmon, respectively, were PIT-tagged and 

released (table 6). The mean fork length of the March group was 133.5 mm (range 80–175 mm) and the 

mean fork length of the June group was 81.1 mm (range 65–110 mm). A total of 489 fish were PITtagged and released with a mean fork length of 114.8 mm (range 70–145 mm; table 6) in September. 

We experienced pre- and post-tagging mortality and minimal PIT tag loss. There were no pre- or 

post-tag mortalities with the hatchery Chinook salmon. Percent mortality between PIT-tagging and 

release of the fish was 0.2 percent in March (1 of 505), 0.6 percent in June (3 of 508), and 0.2 percent in 

September (1 of 491). During all three PIT-tagging sessions, fish were held between 7 and 29 days after 

tagging. Some hatchery fish shed their PIT tags post-tagging. In March, 0.2 percent (1 of 505) of the 

hatchery fish shed their PIT tags and, in September, 0.2 percent (1 of 491) shed their PIT tags. There 

were no shed tags in June. For the wild Chinook salmon, there was a 34.8 percent pre-tag mortality rate 

(8 of 23) and an acoustic+PIT post-tag mortality rate of 50.0 percent (2 of 4). Additionally, the post-tag 

mortality rate of PIT-tagged wild fish was 27.3 percent (3 of 11). 

We omitted 11 acoustic+PIT-tagged fish from analyses because the positions in the cul-de-sac 

indicated predation, shed acoustic tag, or egregious positions. The total number of fish with acoustic 

tags used in analyses was 523. Seven acoustic tags were not detected in the study area during the study, 

including both of the PFFC-collected wild Chinook salmon. 

Travel Times

Travel time varied by area of reservoir. The median travel time from release to the first detection 

at the log boom was 4.1 days for the 94.1 percent of fish that were detected at the log boom (492 of 523; 

fig. 16). Of the Chinook salmon detected at the log boom after PFFC operations began, 80.4 percent 

(377 of 491) were detected within 10 m of the tower face within the remaining life of the acoustic 

transmitter. In contrast, 63.2 percent (299 of 491) of fish were detected near the PFFC entrance after 

detection at the log boom after PFFC operations began. Median travel time from the log boom was 6.1 

days to the tower face and 24.6 days to the PFFC entrance. The mean number of trips each fish made 

from the log boom to within 10 m of the PFFC was 1.9 (range 1–12). The mean number of trips that 

each fish made from the log boom to within 10 m of the tower was higher than the mean number of the 

trips to the PFFC (mean 3.0, range 1–24).

Five acoustic+PIT-tagged fish were collected in the PFFC. Each fish made between one and four 

trips to the PFFC (each trip defined by a detection at the log boom), with a mean of 2.4 trips per fish. 

The 12 total trips from the log boom to within 10 m of the PFFC entrance ranged from 6.6 hours to 27.8 

days, with a mean of 10.6 days, and consisted of two PFFC Low operation treatments, nine PFFC High 

operation treatments, and one PFFC off period. For the three fish that made multiple trips to the PFFC 

entrance, their last trip from the log boom was less than 1 day. The total time from first detection near 

the PFFC entrance to the last JSTATS detection ranged from 14.5 to 30.9 days for the three fish that 

made multiple trips to the PFFC entrance. At time of collection, four fish were collected during a High 

treatment at night and one fish was collected during a Low treatment during the day. 
32 

Figure 16. Graphs of travel time (days) from release of Chinook salmon to first detection at the log boom and from 

the log boom to within 10 meters (m) of the entrance to the water temperature control tower (Tower) or the portable 

floating fish collector (PFFC) after September 14, 2015, Cougar Reservoir, Oregon, 2015–16. Open circles indicate 

censored observations.

Depths in the Cul-de-Sac

Depths of fish positioned within 20 m of the PFFC and tower varied by month. The mean of the 

median hourly depths of each fish near the PFFC and tower ranged from 7.5 to 10.7 m between 

September and December, but was around 6.3 m in January as sample sizes decreased. Fish were 

shallower during the night than during the day in the warmer months but deeper at night in November 

and December (table 7, figs. 17 and 18). Eighty percent of all fish positioned in the cul-de-sac during 

the 2015–16 study period were less than 13 m deep (fig. 19). At the depth of the PFFC entrance (0–3 

m), between 8.6 and 25.8 percent of fish were present by month (fig. 19). 
33 

Table 7. Summary of the mean of the median hourly depths (in meters) of each fish positioned within 20 meters of 

the water temperature control tower (Tower) and portable floating fish collector (PFFC) from September 14, 2015,

to the 90th percentile of each acoustic tag life in Cougar Reservoir, Oregon, 2015–16. 

[N, sample size; SE, standard error]

Month Diel period PFFC Tower

N Depth SE N Depth SE

September Overall 135 8.5 3.4 133 7.5 2.8

Day 111 9.9 2.7 112 8.3 2.3

Night 109 8.7 2.1 114 7.1 2.4

October Overall 255 10.7 4.7 254 8.5 4.7

Day 232 11.9 4.0 235 8.2 4.1

Night 221 9.7 3.7 216 8.1 3.6

November Overall 163 9.4 5.5 157 8.6 5.6

Day 116 7.8 4.0 116 7.0 3.7

Night 131 10.9 6.1 117 11.2 6.1

December Overall 106 8.1 4.3 102 8.4 4.5

Day 59 7.4 2.5 53 7.7 2.7

Night 85 10.6 4.7 80 11.5 5.7

January Overall 39 6.1 3.8 35 6.5 3.8

Day 28 6.8 3.3 17 7.5 3.5

Night 33 6.0 3.9 30 5.4 3.4
34 

Figure 17. Boxplots of the hourly depths (in meters) of acoustic+PIT-tagged juvenile Chinook salmon with position 

estimates within 20 meters of the entrance to the portable floating fish collector (PFFC) at Cougar Reservoir, 

Oregon, September 14, 2015–January 26, 2016. Data summarized are the median hourly depths of each fish 

present at the month indicated during the PFFC operation period. Boxes range from the 25th to 75th percentiles

with a line indicating the median, whiskers represent the 10th and 90th percentiles, and dots represent 5th and 95th 

percentiles. Boxes without whiskers contained insufficient data for them to be estimated. Samples sizes represent 

the number of fish (N) in the hourly box. 
35 

Figure 18. Boxplots of the hourly depths (in meters) of acoustic+PIT-tagged juvenile Chinook salmon with position 

estimates within 20 meters of the entrance to the water temperature control tower at Cougar Reservoir, Oregon, 

September 14, 2015–January 26, 2016. Data summarized are the median hourly depths of each fish present at the 

month indicated during the portable floating fish collector operation period. Boxes range from the 25th to 75th 

percentiles with a line indicating the median, whiskers represent the 10th and 90th percentiles, and dots represent 

5th and 95th percentiles. Boxes without whiskers contained insufficient data for them to be estimated. Samples 

sizes represent the number of fish (N) in the hourly box.
36 

Figure 19. Graphs of acoustic+PIT-tagged fish depths by month (blue bars) and cumulative (black lines) by 3-

meter bins in the cul-de-sac at Cougar Reservoir, Oregon, 2015–16.
37 

Temperature Selection

The acoustic+PIT-tagged fish near the tower and PFFC primarily were in water temperatures 

corresponding with a mean depth of 8.6 m throughout the study period. The acoustic+PIT-tagged fish 

near the tower and PFFC were in water temperatures with a mean of 9.6 °C and at a mean depth of 8.2 

m in September. The tagged fish were in water temperatures with a mean of 12.2 °C and a mean depth 

of 8.5 m in October (fig. 20). After October, water temperatures down to 1,501 ft (the deepest 

temperature recorded) generally were homothermous in the cul-de-sac from top to bottom. As the

months progressed, fish generally used progressively cooler water as it was available (fig. 21). The 

results from data of fish within 20 m of the PFFC entrance (figs. 20 and 21, top graphs) are similar to 

those within 20 m of the tower entrance (figs. 20 and 21, bottom graphs). Water temperatures recorded 

at the USACE string attached to the tower and USGS temperature strings deployed at various locations 

in the cul-de-sac are compared in appendix F. 

Figure 20. Graphs of mean daily fish depth (solid circles) within 20 meters of the portable floating fish collector 

entrance (PFFC, top) and within 20 meters of the water temperature control tower entrance (Tower, bottom) and 

hourly water temperatures (in degrees Celsius) in Cougar Reservoir, Oregon, 2015–16. Vertical lines represent the 

daily minimum and maximum fish depths.
38 

Figure 21. Graphs of the standardized resource selection index for fish positioned within 20 meters of the portable 

floating fish collector entrance (PFFC; top) and within 20 meters of the water temperature control tower entrance 

(Tower; bottom) at Cougar Reservoir, Oregon, 2015–16.

Spatial Intensity of Use

In the Cul-de-Sac

The number of tagged fish used in utilization distributions (UDs) ranged from 10 to 198, with a 

median of 48 among the 100 levels of month, diel period, treatment, and depth strata. Within these 

strata, the number of bursts per fish ranged from 1 to 28 and the number of positions per fish ranged 

from 15 to 19,081. 

The data supported few differences in the spatial intensity of use at the various levels of month, 

diel period, treatment, and depth strata. The UDOIs indicated there was a higher level of similarity at the 

95th percentile of the UDs than at the 50th percentile of the UDs in all cases, indicating a similarity in 

general spatial use, but differences in the areas with the highest probabilities of presence (often referred 

to as the “core area” of habitat use in terrestrial ecology). The similarity in UDs among months within 

treatment, diel period, and depth strata diminished as the time between months increased (for example, 

September was similar to October, but much different than January), some of which likely reflects the 

changing spatial area of the cul-de-sac as the water surface elevation changed over time (appendix G, 

fig. G1). Similarly, the UDs generally were similar between treatments at the 95th percentile, but 
39 

showed little similarity at the 50th percentile, and the UDs were much more similar during the night 

than during the day (appendix G, figs. G2 and G3). The presence of some UDOIs greater than 1.0, the 

value normally associated with a total overlap of spatial use, likely reflects the non-uniform distribution 

of UDs often present in the data (Fieberg and Kochanny, 2005). 

The most consistent differences in spatial distributions were between day and night. During the 

day, the highest probability of presence generally was between the stern of the PFFC and the entrance to 

the tower, as indicated by the preponderance of the 50th percentile of the UD in this area. In some strata, 

the greatest UDs were in locations similar to the PFFC outflow plumes, suggesting the velocity or 

turbulence in those areas may have resulted in fish aggregations; however, we could not determine 

causation because of the lack of a PFFC “off” treatment in the design. During the night, the 50th 

percentile of the UD was much more dispersed than during the day and included the PFFC and much of 

the area upstream of it; however, it rarely included the entrance to the PFFC. These trends are indicated

in data from many of the strata. Data from the 0–3 and 3–6 m depth bins by treatment and diel period 

are shown in figures 22 and 23, and data from all strata are shown in appendix H. Apart from the trends 

in diel period, we also noted a high probability of presence near the mouth of Rush Creek (at the 

southwestern corner of the cul-de-sac) during the day in January, suggesting that the creek outflow was 

attractive to fish during that period. 

Figure 22. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon in the 0–3 

meter depth bin at Cougar Reservoir, Oregon, September 2015–January 2016. Graphs in the top row show UDs 

during the Low treatment in the day (A) and night (C). Graphs in the bottom row show UDs during the High 

treatment in the day (B) and night (D). In each graph, the portable floating fish collector (PFFC) is shown in gray 

near the center and the water temperature control tower is shown in black near the upper right. Black circles 

indicate positions of hydrophones.
40 

Figure 23. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon in the 3–6 

meter depth bin at Cougar Reservoir, Oregon, September 2015–January 2016. Graphs in the top row show UDs

during the Low treatment in the day (A) and night (C). Graphs in the bottom row show UDs during the High 

treatment in the day (B) and night (D). In each graph, the portable floating fish collector (PFFC) is shown in gray 

near the center and the water temperature control tower is shown in black near the upper right. Black circles 

indicate positions of hydrophones.

Near the PFFC Entrance

In addition to examining the spatial intensity of use within the entire cul-de-sac by the tagged 

fish (see section, “Spatial Intensity of Use: In the Cul-de-Sac”), we also calculated and examined UDs 

only for the smaller area in front of the PFFC within a 20-m radius of the entrance and 6 m deep. Thus, 

these UDs represent the intensity of use only within the limited confines of this much smaller volume of 

water for the tagged fish positioned near the PFFC entrance and are unrelated to the intensity of use in 

the cul-de-sac as a whole. The number of fish used in the individual UD calculations for all 

combinations of treatment, photoperiod, and depth strata ranged from 69 to 217. 
41 

The 0–3 and the 3–6 m UDs indicate that, whereas areas encompassing 95 percent of the highest 

fish use included much of the area within a 20-m radius of the entrance, the intensity of use over much 

of this area was low and diffuse, including the area within about 5 m of the PFFC entrance (figs. 24 and 

25). This is particularly apparent in the UDs for the 0–3 m depth bin during both treatments and 

photoperiods where the area nearest the entrance is not included in the 95th percentile of three of the 

UDs (shown as white-colored areas on the graphs, fig. 24). In the UDs for the 3–6 m bin, the entrance is 

encompassed by the 95th percentile of the UDs, but the intensity of use is still low (fig. 25). The areas 

of most intense use, bounded in the UDs within the 50th percentile contour, covered small, compact 

areas that generally were 10–20 m from the entrance for all the strata. 

Figure 24. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon near the 

portable floating fish collector (PFFC) in the 0–3 meter (m) depth bin at Cougar Reservoir, Oregon, September 

2015–January 2016. Graphs in the left column show UDs in the day during the Low (A) and High (B) treatments.

Graphs in the right column show UDs of the same strata at night. The PFFC entrance is shown at the bottom of 

each graph. The 95th percentile of the data is shown and the black lines indicate the 50th percentile contour.
42 

Figure 25. Graphs of the utilization distributions (UDs) of acoustic+PIT-tagged juvenile Chinook salmon near the 

portable floating fish collector (PFFC) in the 3–6 meter (m) depth bin at Cougar Reservoir, Oregon, September 

2015–January 2016. Graphs in the left column show UDs in the day during the Low (A) and High (B) treatments.

Graphs in the right column show UDs of the same strata at night. The PFFC entrance is shown at the bottom of 

each graph. The 95th percentile of the data is shown and the black lines indicate the 50th percentile contour.

Movements Behaviors

In the Cul-de-Sac 

Examinations of the plots of the median tortuosity of fish tracks in the cul-de-sac indicate diel 

differences in the tortuousness of fish movements (figs. 26 and 27). Tortuosity values approaching 0 

indicate increasingly more tortuous or meandering fish tracks, whereas values approaching 1 indicate 

fish tracks that are increasingly more like a straight line. During the day, fish movements had a high 

degree of tortuousness between the PFFC and water temperature control tower, an intermediate degree 

of tortuousness generally west of the PFFC along the shoreline areas, and increasingly more directed or 

straight fish tracks to the south and east of the PFFC (fig. 26A). Median tortuosity values for the 20 × 

20-m cells ranged from 0.28 to 0.41 between the tower and the PFFC, and generally increased with 

distance south of the PFFC to a maximum of 0.95. At night, fish movements were only moderately 

tortuous between the PFFC and tower (0.51–0.67), and increasingly less tortuous with increased 

distance from the PFFC to the south (0.76–0.97; fig. 26B). These diel patterns in fish movement 

behavior were similar between the High and Low treatments for both the 0–3 and the 3–6 m fish depth 

bins (figs. 26 and 27). The number of fish used to calculate the tortuosity of fish movements in the culde-sac ranged from 275 to 368 among the treatment, photoperiod, and depth strata. The number of fish 

used to calculate the median tortuosity for an individual 20 × 20-m cell ranged from 3 to 210, with a 

median of 50 fish per cell among strata. 
43 

Figure 26. Graphs of the distribution of the median tortuosity of acoustic+PIT-tagged juvenile Chinook salmon 

swimming in the 0–3 meter (m) depth bin at Cougar Reservoir, Oregon, September 2015–January 2016. Graphs in 

the top row show distribution of median tortuosity during the Low treatment in the day (A) and night (C). Graphs in 

the bottom row show distribution of median tortuosity during the High treatment in the day (B) and night (D).

Tortuosity values approaching 0 indicate increasingly more tortuous fish tracks, and values approaching 1 indicate 

fish tracks that are increasingly more like a straight line. Black circles indicate positions of hydrophones. White lines 

indicate the 50th percentile contours from the utilization distribution plots above. In each graph, the portable floating 

fish collector (PFFC) is shown in gray near the center and the water temperature control tower is shown in black 

near the upper right.
44 

Figure 27. Graphs of the distribution of the median tortuosity of acoustic+PIT-tagged juvenile Chinook salmon 

swimming in the 3–6 meter (m) depth bin at Cougar Reservoir, Oregon, September 2015–January 2016. Graphs in 

the top row show distribution of median tortuosity during the Low treatment in the day (A) and night (C). Graphs in 

the bottom row show distribution of median tortuosity during the High treatment in the day (B) and night (D).

Tortuosity values approaching 0 indicate increasingly more tortuous fish tracks, and values approaching 1 indicate 

fish tracks that are increasingly more like a straight line. Black circles indicate positions of hydrophones. White lines 

indicate the 50th percentile contours from the utilization distribution plots above. In each graph, the portable floating 

fish collector (PFFC) is shown in gray near the center and the water temperature control tower is shown in black 

near the upper right.

Near the PFFC Entrance 

A total of 262 tagged fish were positioned in front of the PFFC within 10 m of the entrance and 

at depths of 0–6 m. About 61 percent (160) of these fish had at least one burst (trip) with three or more 

locations, and the number of fish in the individual treatment, photoperiod, and depth strata ranged from 

17 to 63. The mean bearings (directions) of the trajectories of fish positioned within the ten 4 × 5-m 

cells in front of the PFFC are shown in appendix I. 
45 

Low numbers of tagged fish near the PFFC in the 0–3 m depth bin made comparisons between 

the treatments difficult during the day (appendix I, fig. I1). Individual cell sample sizes less than 10 

were considered too small to statistically test whether the distribution of trajectory directions were 

uniform (random) or non-uniform. During the day in both treatments, fish positioned about 5–10 m 

from the entrance appeared to be most often moving randomly towards or away from the face of the 

collector with no preference for moving directly towards the entrance (appendix I, fig. I1). Fish that 

were positioned within 5 m of the entrance generally had trajectories directed away from the PFFC 

(appendix I, fig. I1). 

At night for the 0–3 depth bin, small sample sizes for fish positioned within 5 m of the entrance 

again precluded comparisons between treatments as in the day, but larger sample sizes for fish 5–10 m 

away from the entrance permitted testing the distributions of trajectory directions for uniformity. During 

both treatments, fish 5–10 m from the entrance most often had trajectory directions oriented on an axis 

(appendix I, fig. I2; Ps<0.05). That is, fish located directly in front of the entrance generally moved east 

and west parallel to the PFFC; fish located to the west of the entrance generally moved northwest 

towards the west end of the PFFC or to the southeast away from the PFFC, and fish located east of the 

entrance generally moved either northeast towards the east end of the PFFC or southwest away from the 

PFFC. The movement patterns of fish positioned within 5 m of the entrance were ambiguous because of

the small sample sizes, but there was no apparent preference for trajectories oriented towards the PFFC 

entrance (appendix I, fig. I2). 

The trajectories of fish in the 3–6 m depth bin were similar to those for the 0–3 m bin. During 

both treatments during the day, fish most often moved in random directions (Ps>0.10) or away from the 

PFFC (Ps<0.04) whether 5–10 or 0–5 m from the PFFC entrance with no preference for moving 

towards the entrance (appendix I, fig. I3). At night, fish 5–10 m from the entrance generally moved on 

an axis parallel to the collector or toward the east and west ends of the collector (appendix I, fig. I4; 

Ps<0.03). Fish within 5 m of the entrance most often moved in random directions with no preference for 

the direction to the PFFC entrance (Ps>0.05). 

Samples of eight random fish trajectories during the High treatment at night indicate the data 

used to estimate UDs and fish movements near the PFFC (fig. 28). Although these fish approached 

between 5 and 10 m of the PFFC entrance, few fish approached closer than about 5 m. The trajectories 

often were relatively short (fig. 28B, 28D–G) and parallel to the PFFC (fig. 28B, 28F, 28H), but some 

fish milled briefly before moving out of the area (fig. 28A, 28C, 28H).
46 

Figure 28. Graphs of movements of eight randomly selected acoustic+PIT-tagged juvenile Chinook salmon near 

the portable floating fish collector (PFFC; figure parts A–H) during the High treatment in the night at Cougar 

Reservoir, Oregon, 2015–16. Fish were selected from a pool of fish with at least two positions within 10 meters (m) 

of the PFFC entrance. Large circle is the first position of each track, open circles are positions less than or equal to 

3 meters deep, and filled circles are positions greater than 3 meters deep. The PFFC entrance is shown at the 

bottom of each plate.
47 

Collection in the PFFC and Dam Passage

All the acoustic+PIT-tagged fish that passed Cougar Dam did so after the beginning of PFFC 

treatments on September 14, 2015. Of the 523 fish released, 22.9 percent (N=120) were assigned 

passage through the tower or PFFC within the 90th percentile of the acoustic tag life. No fish were 

assigned passage after the 90th percentile of the acoustic tag life. During the PFFC treatments, 37 

acoustic+PIT-tagged fish passed the tower during the Low treatment, 54 fish passed during the High 

treatment, and 24 fish were last detected on the acoustic telemetry system when the PFFC was off. Five 

acoustic+PIT-tagged fish were collected by the PFFC—four fish during the High treatment at night and 

one fish during the Low treatment during the day. Three of these fish were live when the collection was 

examined and were transported to the tailrace for release. All the 120 acoustic+PIT-tagged fish assigned 

passage were of hatchery origin. 

Most of the acoustic+PIT-tagged fish were detected in the cul-de-sac and near the PFFC or 

tower, but few entered a passage route. Of the 523 fish in the study, over 94 percent were detected at the 

log boom (reservoir passage efficiency, RPE) and most fish detected at the log boom subsequently were 

detected in the cul-de-sac, resulting in a forebay passage efficiency (FBE) of 0.967 (table 8). The dam 

passage efficiency season-wide (DPE) and during the PFFC treatments (DPETREAT) was 0.244 (table 8).

The DPETREAT period encompasses all on and off periods once the PFFC block treatments began on 

September 14, 2015, and includes 24 fish passing during the PFFC off condition. The DPE was 0.087 

(38 of 435) during the Low treatment was 0.123 during the High treatment (58 of 471). The discovery 

efficiency (DE) at the PFFC was 0.290 during the Low treatment and 0.261 during the High treatment 

(table 9). The DEs at the tower did not differ significantly between treatments (P=0.464), but were 

greater than those at the PFFC (table 9). The entrance efficiency (EE) and fish collection efficiency 

(FCE) through the PFFC were both less than 1 percent during each treatment (table 9). FCEs based on a 

denominator of fish numbers in the forebay (FCEFB) or in the cul-de-sac (FCECDS) were similar because 

of the high FBE. Six acoustic+PIT-tagged fish passed the PIT antenna, but only five fish were detected 

by the PFFC PIT interrogator—one fish was collected when the antenna was out of service. Five of the 

six fish that passed the antenna were collected in the PFFC (fig. 29). The last burst (contiguous positions 

without a 30-m gap) in the cul-de-sac prior to the collection of these five fish are shown in figure 29. 

Blue tracks of fish positions indicate no obvious guidance from the attraction pumps into the PFFC (fig. 

29). The EE at the tower was 0.143 during the Low treatment and 0.180 during the High treatment. Fish 

collection effectiveness (FCF) of the two routes was at or near zero during both treatments. An alternate 

method to estimate effectiveness is to divide route passage by passage through all routes (PFFC and 

tower), resulting in an estimate of the proportion of passage afforded by each route. The FCF calculated 

using the alternate method for the PFFC was 0.026 for Low treatment and 0.069 for the High treatment. 

Corresponding estimates for the tower were 0.974 for the Low treatment and 0.931 for the High 

treatment.
48 

Table 8. Reservoir passage efficiency, forebay passage efficiency, and dam passage efficiency from acoustictagged juvenile Chinook salmon at Cougar Reservoir, Oregon, 2015–16. 

[Metrics RPE, DPE, and FBE were calculated over the entire study period (September 10, 2015–April 23, 2016) and

DPETREAT was calculated from data beginning when portable floating fish collector (PFFC) treatments began on September

14, 2015. Metric: DPE, dam passage efficiency; FBE, forebay passage efficiency; RPE, reservoir passage efficiency; Treat, 

time period during PFFC treatments. Sample size: number of tagged fish in the denominator of the estimate. 95-percent CI: 

95-percent lower and upper confidence intervals]

Metric Sample size Estimate 95-percent CI

RPE 523 0.941 0.921, 0.961

FBE 491 0.967 0.952, 0.983

DPE 492 0.244 0.206, 0.282

DPETREAT 491 0.244 0.206, 0.282

Table 9. Passage metric estimates and lower and upper 95-percent confidence intervals during portable floating 

fish collector treatments from acoustic-tagged juvenile Chinook salmon at Cougar Reservoir, Oregon, 2015–16. 

[; Metric: CDS, cul-de-sac; DE, discovery efficiency; EE, entrance efficiency; FB, forebay; FCE, fish collection efficiency; 

FCF, fish collection effectiveness. Sample size: number of tagged fish in the denominator of the estimate. 95-percent CI:

95-percent lower and upper confidence intervals. P: probability. Abbreviations: PFFC, portable floating fish collector; 

Tower, water temperature control tower; NA, not applicable]

Metric

PFFC Low treatment PFFC High treatment Difference

Sample 

size Estimate 95-percent CI Sample size Estimate 95-percent CI Odds ratio 95-percent CI P 

PFFC

DE 376 0.290 0.244, 0.336 421 0.261 0.219, 0.303 1.154 0.846, 1.575 0.366

EE 109 0.009 0.000, 0.027 110 0.036 0.001, 0.071 0.245 0.027, 2.231 0.178

FCEFB 435 0.002 0.000, 0.007 471 0.008 0.000, 0.017 0.269 0.030, 2.416 0.209

FCECDS 397 0.003 0.000, 0.007 437 0.009 0.000, 0.027 0.273 0.030, 2.456 0.215

FCF NA 0.000 NA NA 0.000 NA NA NA NA

Tower

DE 376 0.689 0.642, 0.736 421 0.713 0.669, 0.756 0.893 0.659, 1.210 0.464

EE 259 0.143 0.100, 0.186 300 0.180 0.137, 0.224 0.759 0.481, 1.198 0.236

FCEFB 435 0.085 0.059, 0.111 471 0.115 0.086, 0.143 0.718 0.462, 1.115 0.139

FCECDS 397 0.093 0.065, 0.122 437 0.124 0.093, 0.154 0.729 0.468, 1.135 0.160

FCF NA 0.001 NA NA 0.002 NA NA NA NA
49 

Figure 29. Graphs of movements of five acoustic+PIT-tagged juvenile Chinook salmon collected in the portable 

floating fish collector (PFFC; figure parts A–E) at Cougar Reservoir, Oregon, 2015–16. The yellow triangle is the 

first position of each track, the red square is the last position prior to PFFC collection, and black circles indicate 

positions of hydrophones. The PFFC is shown near the center of each graph and the water temperature control 

tower is at the top center of each graph.
50 

Some of the acoustic+PIT-tagged fish passing Cougar Dam were detected as far downstream as 

Portland, Oregon (332 rkm). A total of 35.8 percent (N=43) of the 120 tagged juvenile Chinook salmon 

passing Cougar Dam within the life of the acoustic transmitter were detected at acoustic telemetry or 

PIT sites downstream of Cougar Dam. Of those fish, 23.3 percent (N=10) were detected at the acoustic 

telemetry sites in the tailraces (9 below the powerhouse, 1 below the RO), 41.9 percent (N=18) were 

detected at the acoustic telemetry site at the USGS streamgage on the South Fork McKenzie River, and 

23.3 percent (N=10) were detected at a site 2.3 rkm downstream of Cougar Dam. Detection at the 

powerhouse or RO tailrace does not necessarily indicate passage route because fish can move between 

tailraces after passage (Beeman and others, 2014a). We estimate the probability of passing all the 

downstream JSATS sites without being detected was about 0.20. Detecting tagged fish in this area was 

not a priority for the study, but was used as ancillary information about fish passage. Fish also were 

detected at PIT sites downstream of Cougar Dam. Of the 43 fish, 11.6 percent (N=5) were detected at 

Oregon Department of Fish and Wildlife screw traps in the tailrace, 16.3 percent (N=7) were detected at 

the Leaburg Dam juvenile fish bypass, and 4.7 percent (N=2) were detected at Willamette Falls. No fish 

were detected at Walterville, the Columbia River estuary trawl, or at the East Sand Island PIT sites.

Few of the juvenile Chinook salmon tagged solely with PIT tags were detected at the PFFC 

interrogator or downstream of Cougar Dam. A total of 0.4 percent (2 of 503) of the fish released in 

March, 0.2 percent (1 of 505) of fish released in June, and 1.0 percent (5 of 489) of the fish released in 

September were detected at downstream PIT sites. The March-released fish were detected downstream 

in March while the June- and September-released fish were detected downstream in late-June, October, 

and December 2015, or in February 2016. One PIT tag from a March-released fish was recovered at 

East Sand Island near the mouth of the Columbia River in 2015. Four of the fish released in March, two 

of the fish released in June, and one fish released in September were collected in the PFFC, indicating 

that the remaining fish passed through the tower. Of the nine fish that passed the PFFC PIT antenna, 

eight were detected and seven were collected. Some fish were detected multiple times on the PIT 

antenna, sometimes over multiple hours, indicating that the antenna was located in an area without 

complete fish entrainment. Four of the collected fish were live and three were dead when examined (one 

in March and two in October). After accounting for fish that left the reservoir through the tower, the 

PFFC fish collection efficiency of PIT-tagged fish was less than 0.008 for each of the release groups. 

Detections of acoustic+PIT-tagged fish suggest that the low numbers of fish collected by the 

PFFC owed in part to the low proportion of fish in the cul-de-sac that came near the collector entrance.

A large proportion of fish released were detected in the cul-de-sac (0.659 in the Low treatment, 0.785 in 

the High treatment; fig. 30), but relatively few of those were detected within 10 m of the PFFC entrance. 

The cumulative proportion detected as a function of the fish released is shown in figure 30. The steep 

slopes between the cul-de-sac and 10- and 1-m zones in figure 30 suggest these zones contribute largely 

to the low collection efficiencies. Roughly 29 percent of the fish detected in the cul-de-sac were 

detected within 10 m of the PFFC entrance during the Low treatment (26 percent during the High 

treatment), and few of those fish were detected within 1 m of the PFFC entrance (1 percent in Low and 

High treatments).
51 

Figure 30. Graph showing proportion of released acoustic+PIT-tagged fish detected during treatment operations of 

the portable floating fish collector (PFFC) at zones in Cougar Reservoir, Oregon, 2015–16. The 10-meter (m) and 

1-m zones are in reference to the distance from the PFFC entrance. Low, Low treatment; High, High treatment.

Discussion

Chinook salmon fry are a target life stage for collection and dam passage at Cougar Reservoir 

and Dam, but little is known about their movements and distribution. Monzyk and others (2014) 

reported that catches increased in the downstream direction over time and found fry along shorelines 

throughout the reservoir by June. The PFFC catch of subyearling Chinook salmon during 2015–16 

began when the trap was first operated in March, peaked later that month, decreased until the trap was 

shut down during the warm summer months, and resumed at a low level when the trap was operated 

again in fall and winter with little catch after mid-December. The data we collected were from a life 

stage larger than fry to enable marking with PIT tags and acoustic tags for a thorough study of migration 

and distribution. 

We used fish from an experimental hatchery program instead of naturally produced fish from 

within the reservoir because of the low catches of naturally produced fish in previous years. For 

example, average catch of juvenile Chinook salmon at least 95 mm in fork length was 0.14 during 

spring and 2.87 during fall for individual sets using a Lampara seine (Beeman and others, 2012). The 

hatchery fish we used were raised by Oregon State University at the Fish Performance and Genetics 

Laboratory in Corvallis, Oregon, as part of the Wild Fish Surrogate Project funded by USACE. In terms 

of length, the surrogate fish we used were representative of subyearling age naturally produced fish in 

fall/winter and yearling (overwintering) fish in spring and summer. Naturally produced Chinook salmon 

usually begin entering Cougar Reservoir in February at a length of less than 40 mm, grow rapidly in the 

reservoir reaching about 65 mm in late June or July when we released PIT-tagged fish of about that size, 

and are 95 mm or larger by early fall when we released acoustic+PIT-tagged fish of a similar size

(Monzyk and others, 2014). 
52 

The biological and hydraulic performance of the PFFC during fall and winter 2015–16 was 

improved over those performances prior to the modifications to the PFFC during winter 2014–15. The 

modifications included raising the PFFC internal structure (entrance, dewatering flume, and collection 

box) about 46 cm relative to the flotation to reduce the volume of inflow, modifying the dewatering 

screens to reduce vibration and other issues, repositioning the anchors to enable the trap to be moved 

closer to the tower as originally intended, and several others changes to improve safety and convenience 

when handling fish. 

Raising the internal structure of the PFFC and perhaps the modifications to the dewatering 

screens resulted in better control of the inflow. The reduction of the inflow volume enabled the water 

velocity profile to be improved from that in 2014, resulting in a smooth increase in water velocity from 

about 1 ft/s slightly upstream of the entrance to a maximum of nearly 3 ft/s 18.7 ft downstream of the 

entrance. HDR Engineering, Inc. (2015) measured a velocity of about 4 ft/s 20 ft downstream of the 

entrance. Overall, the maximum measured inflow velocity was about 2 ft/s less than designed. Better 

control of the inflow improved conditions in the collection box, which likely contributed to the lower 

trap mortality, (about 30 percent of the values from the previous evaluation) and may have contributed 

to the reduction in handling mortality as well (Beeman and others, 2016). 

Trap catch was nearly three times greater in 2015 than in 2014 when similar sampling periods 

were compared, and an order of magnitude greater in 2015 over both of the entire study seasons. Catch 

of juvenile Chinook salmon in 2014 and 2015 was greatest during spring and during the High treatment.

In 2014, the trap was operated almost continuously, including the warm water period from July through 

August, whereas in 2015 the trap was off during that period because of the potential for increased fish 

mortality, as stipulated by State and Federal fish collection permits. The catch during mid-summer in 

2014 consisted exclusively of warm-water species and likely was a result of the shallow trap entrance 

and deep depths of juvenile salmonids during that time. Catch of juvenile salmonids could be low 

during the warm summer months even with a much deeper trap entrance, given the warm water 

temperatures and deep depths of juvenile salmonids evident in 2014 and 2015. Data from the summer of 

2014 suggested that juvenile salmonids had a strong preference for water temperatures of about 13–15 

°C, but data from fall and winter 2015–16 did not support that finding. 

Moving the PFFC closer to the tower likely contributed to the increase in catch from the 

previous year, but as in 2014, the area with highest use by tagged fish was between the PFFC and the 

tower. Juvenile salmon are known to be attracted to turbulence and to follow flow and shear lines, 

common conditions between the PFFC and the tower (Coutant 2001; Tiffan and others, 2009; Goodwin 

and others, 2014). The areas with the highest probability of use were not only between the PFFC and 

tower, but often in the specific areas of the PFFC outflow, suggesting that the PFFC attracted fish to its 

stern. We could not assess causality of that phenomenon because of the lack of an “off” condition in the 

treatment schedule. Reanalysis of fish position data collected prior to deploying the PFFC (in 2011 and 

2012) may be useful for that purpose (see Beeman and others, 2013; 2014b). There also was little use of 

the area directly upstream of the PFFC entrance during 2014 and 2015–16, suggesting that the fish may 

have avoided that area.

The data support the conclusion that the low FCE of the PFFC was owing to limited presence of 

fish in the area at least 10 m upstream of the PFFC entrance. Using the zones described by Sweeney and 

others (2007), we found poor fish guidance through the Discovery Zone (10–100 m from a passage 

entrance where juvenile salmonids first encounter a surface outlet flow net) and Decision Zone (within 

10 m of an entrance where juvenile salmonids choose to enter or reject an entrance). The small flow net 

in front of the PFFC likely restricted the Discovery Zone to within a few meters of the entrance. The 

probability of acoustic+PIT-tagged fish released near the head of the reservoir being detected within the 

cul-de-sac was generally high (0.66–0.78, depending on PFFC treatment), but there was only about a 
53 

0.20 probability of being detected within 10 m of the PFFC entrance and less than 0.01 probability of 

being detected within 1 m of the entrance. The 10-second repetition interval of the acoustic tags may 

have reduced the latter number from the true value owing to fish swimming past the 1-m zone between 

tag pulses, but the trend from the collection supports a low presence of fish near the entrance. Only five 

of the acoustic+PIT-tagged fish detected within 10 m of the PFFC entrance were collected (1 of 109 

during the Low treatment and 4 of 110 during the High treatment), further supporting a need to focus on 

improving conditions in the Discovery or Decision zones. 

The ability of fish to freely swim throughout the cul-de-sac likely played an important role in the 

low FCE of the PFFC. The high probability of fish presence behind the PFFC and low probability of 

presence in front of it mark a significant factor in the low FCE. Fish collection efficiency would be 

improved if the fish residing behind the PFFC were restricted to the area in front of it. Guide or block 

nets together with a net-transition structure affixed to the trap entrance have been used for this purpose 

at other high-head dams with surface collectors in the Pacific Northwest. To our knowledge, these 

means have been part of most trap designs from the beginning and their contribution to the overall FCE 

has not been tested; however, the catch of the “gulper” at Upper Baker Lake doubled after a nettransition structure and redesigned nets were installed in 2004, and was about 150 percent greater than

pre-installation catch the following year (written. commun., Nick Veretto, Puget Sound Energy, July 17, 

2015). Few of the collectors in place at the time of this report had FCEs meeting expectations, but FCEs 

were likely greater than if fish were allowed to pass behind the entrance of the collectors. Use of guide 

or block nets at Cougar Reservoir would be complicated by the large fluctuations in reservoir elevation 

and perhaps the uncontrolled floating woody debris in the reservoir; however, these factors could be 

actively mitigated as they have been to some extent at other sites in the region. 

Performance of future downstream passage alternatives at Cougar Dam would be enhanced by 

having a deeper entrance and larger inflow than the PFFC. The average of the median hourly fish depths 

ranged from 3.7 to 13.7 m, and the 80th percentile of fish depths in the cul-de-sac during the 2015–16 

study period was at least 10 m, depending on the month. Surface collectors at most other sites in the 

region have entrances about 10 m deep, including those at Upper and Lower Baker dams, Cushman 

Dam Number 2, Swift Dam, Round Butte Dam, and North Fork Dam. The inflow volumes of the 

collectors at those sites ranged from 250 ft3

/s at Cushman Dam Number 2 to about 1,000 ft3/s at North 

Fork Dam. 
54 

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58 

Appendix A. Summary of Dam Operating Conditions Calculated from Hourly 

Data at Cougar Dam, Oregon, 2015–16

Table A1. Summary statistics of dam operations and environmental conditions at Cougar Reservoir, Oregon, 

September 10, 2015–April 23, 2016. 

[Spill is combined regulating outlet and diversion tunnel discharge. SD, standard deviation; ft3

/s, cubic foot per second]

Dam operating conditions Period Mean Median Range SD

Total project (ft

3

/s) Overall 1,142.9 1,020.0 290.0–3,160.0 850.0

Day 1,109.6 760.0 290.0–3,160.0 844.6

Night 1,175.0 1,050.0 290.0–3,130.0 854.1

Powerhouse (ft

3

/s) Overall 157.1 0.0 0.0–1,280.0 190.9

Day 157.8 0.0 0.0–840.0 190.9

Night 156.5 0.0 0.0–1,280.0 191.0

Spill (ft

3

/s) Overall 985.4 740.0 0.0–3,160.0 960.0

Day 951.0 680.0 0.0–3,160.0 954.4

Night 1,018.5 740.0 0.0–3,130.0 964.4

Forebay elevation (feet above National 

Geodetic Vertical Datum of 1929) Overall 1,535.4 1,538.9 1,456.0–1,579.2 32.6

Day 1,533.7 1,536.8 1,456.0–1,579.1 34.2

Night 1,536.9 1,540.5 1,456.0–1,579.2 30.9

Head over the weir gates Overall 14.0 14.2 10.5–17.2 1.9

Day 13.9 14.2 10.5–17.2 1.9

Night 14.0 14.2 10.5–17.1 1.8

Water temperature (degrees Celsius) Overall 9.1 7.5 4.6–17.2 3.8

Day 9.4 8.4 4.6–17.2 3.8

Night 8.9 7.4 4.6–17.0 3.7

Table A2. Summary statistics of spill operations at Cougar Reservoir, Oregon, September 10, 2015–April 23, 

2016. 

[The diversion tunnel was in use from March 3 at 1 p.m. through April 20, 2016 at 1 p.m. All other spill discharge is 

summarized as regulating outlet. SD, standard deviation; ft3

/s, cubic foot per second]

Dam operating conditions Period Mean Median Range SD

Regulating outlet (ft

3

/s) Overall 873.4 650.0 0.0–3,160 942.9

Day 824.4 550.0 0.0–3,160 933.5

Night 917.2 740.0 0.0–3,130 949.4

Diversion tunnel (ft

3

/s) Overall 1,402.3 1,840.0 0.0–2,970 907.0

Day 1,347.0 1,750.0 0.0–2,970 910.3

Night 1,473.4 1,890.0 0.0–2,920 898.7
59 

Appendix B. Performance of the Portable Floating Fish Collector Passive 

Integrated Transponder Interrogator 

Introduction

Detection probabilities of telemetry systems often are imperfect, so it is important to estimate 

and account for detection probability when estimating tag presence using this methodology. In the 

context of this study, it is important to use estimates of detection probability of the passive integrated 

transponder (PIT) interrogator within the portable floating fish collector (PFFC) when estimating the 

numbers of tagged fish present. We, therefore, estimated detection probability of the system using the 

full-duplex PIT tag model used to tag juvenile Chinook salmon in Cougar Reservoir. There also are bull 

trout (Salvelinus confluentus) implanted with half-duplex PIT tags within the reservoir, but detection 

probabilities of half-duplex interrogators generally are higher than full-duplex systems, so we did not 

use half-duplex tags in our evaluation. 

Methods

We released test PIT tags through the PFFC to estimate the detection probability of the PIT

detection system. We ran a simulation during our first year of PFFC evaluation in 2014 to determine the 

number of test tags required using Program MARK (White and Burnham, 1999) and determined that 

releases of greater than 150 tags would not substantially improve the 95-percent confidence intervals of 

detection probability (Beeman and others, 2016). Test tags were attached to a 1-m section of 40-mm 

polyvinyl chloride (PVC) (to keep tag orientation constant and parallel to the inflow) with adjustable 

floatation on each end (to set the depth). Detection probabilities of physical and virtual tags were 

estimated using a three-occasion Cormack-Jolly-Seber mark-recapture model (Cormack, 1964; Jolly, 

1965; Seber, 1965) in Program MARK. 

Estimating the continuous detection probabilities of the virtual tag was based on the evaluation 

of a suite of models representing varying assumptions thought to affect detection probability. Models 

evaluated ranged from an overall model assuming no effect of time or treatment, a model based on 

treatment independence with no effect of time, models based on varying time intervals with no 

treatment effect, and a model with the interaction of treatment and time based on the block design. The 

probabilities of detection were estimated from model-averaged coefficients (Burnham and Anderson, 

2002). 

Results

Initial physical tag testing was done post-reconstruction at the beginning of March. Although the 

final post-commissioning settings may have changed slightly (ballast water levels, screen porosity, etc.), 

the pump attraction settings and conditions were similar to the final operational settings. The initial 

testing suggested that the detection of physical and virtual tags were similar (1.00, 0.96) and similar to 

pre-reconstruction (0.90) found in 2014 (Beeman and others, 2016). Virtual tags, therefore, were used to 

monitor detection probabilities.
60 

In June, additional tests were conducted with physical tags to verify detection probabilities 

during actual operational conditions. The tests were incomplete, as one of the test sticks became lodged 

in the attraction pumps causing a system outage. Furthermore, testing was postponed because of

concerns over damaging the attraction pumps, and the PFFC was off during summer months during 

warm water temperatures. Detection probabilities were 0.947 (0.897, 0.973 lower and upper 95-percent

confidence interval) for the completed low treatment test and 1.000 for the partial high treatment test.

In early November, there was a marked decline in virtual tag detections resulting from a nearly 

completely flooded antenna node. Post-replacement the detections of virtual tags remained low as 

system troubleshooting occurred. Physical tag testing was not completed because of inconsistent trap 

and antenna functionality prior to and post trap removal for reservoir drawdown. 

The model results of detection probabilities based on virtual tags indicated likely no support for 

differences within season, node, and treatment indicated with delta AICc greater than 260 units. The 

most supported models contained block, with the interaction between block and treatment having the 

highest weight and moderate support for a model based on block alone (table B1). The model point 

estimates ranged from 0.100 to 1.000 among blocks and treatments including when the antenna node 

was flooded. The mean detection probability for the PIT-tag interrogator outside the known antenna 

malfunction was 0.957 (fig. B1).

Table B1. Suite of three-occasion models for the analysis of detection probabilities of virtual tags from the passive 

integrated transponder interrogator on the portable floating fish collector (PFFC) at Cougar Reservoir, Oregon, 

2015–16. 

[AICc, Akaike Information Criterion with an adjustment for effects of sample size; Num par, number of parameters] 

Model AICc Delta AICc AICc 

weights

Model 

likelihood Num par Deviance

1 P(Block*Treatment) 1,461.956 0.000 0.927 1.000 72 0.000

2 P(Block) 1,467.042 5.086 0.073 0.079 40 69.832

3 P(Treatment*Node) 1,722.706 260.750 0.000 0.000 10 385.811

4 P(Node) 1,743.923 281.967 0.000 0.000 6 415.042

5 P(Season) 2,093.264 631.308 0.000 0.000 6 764.383

6 P(Treatment*Season) 2,096.752 634.796 0.000 0.000 10 759.857

7 P(Treatment) 2,402.450 940.494 0.000 0.000 6 1073.568
61 

Figure B1. Estimated detection probabilities of virtual full-duplex passive integrated transponder (PIT) tags at the 

portable floating fish collector PIT interrogator, Cougar Reservoir, Oregon, 2015–16. The portable floating fish 

collector (PFFC) was not operational for blocks 9–14 because of high water temperature concerns. The shaded 

area indicates periods when the PIT interrogator node was nearly completely flooded between November 3 and 

December 15, 2015.
62 

Appendix C. Transmitter Life and Transmitter Loss Tests

Introduction

The operational life of a subset of the acoustic transmitters used in this study was empirically 

determined to define an appropriate follow-up time for analysis. The purpose of defining a follow-up 

time was to ensure a high probability of transmitter functionality during the period of analysis. 

In addition to determining the operational life of the acoustic transmitters, we also evaluated 

surgical incision and transmitter loss. Panther and others (2011) found greater than 12 percent 

transmitter loss at 98 days post-surgery when the incision was located on the mid-ventral line and water 

temperature was 12 °C. In contrast, the muscle-cutting incision, which was located 3 mm from and 

parallel to the mid-ventral line, had about 1-percent transmitter loss at 98 days post-surgery (Panther and 

others, 2011) at 12 °C. The Surgical Protocols Steering Committee (2011) document, which lists the 

protocols for acoustic tagging projects funded by the USACE, specifies the mid-ventral line as the 

location of the surgical incision; however, we found similar results to Panther and others (2011) in a 

laboratory study in 2014 at 162 days post-surgery (John W. Beeman, Amy C. Hansen, Jamie M. 

Sprando, U.S. Geological Survey, unpub. data, 2014). We tested transmitter loss using the musclecutting incision in juvenile fall Chinook salmon from Spring Creek Hatchery, Washington. 

Methods

We selected 50 acoustic transmitters from the fall tags and empirically determined tag life. We 

activated the tags on September 13, 2015, sorted them into two groups of 25 transmitters, and surgically

implanted acoustic and PIT tags in fish on September 14, 2015. We following Surgical Protocols 

Steering Committee (2011), except that we used the muscle-cutting incision, which was located 3 mm 

from and parallel to the mid-ventral line (Panther and others, 2011). A second group of 50 fish were 

surgically tagged in the same manner on September 29, 2015. All tagged fish were placed in replicate 

1.5-m diameter circular tanks (N=50 in each tank) with flowing well water and automatic feeders at the 

U.S. Geological Survey Columbia River Research Laboratory in Cook, Washington. Feed was provided 

daily, 7 days a week, at 1.5 percent of body weight. A subsample of fish (28 percent) was measured at 

60, 99, and 177 days post-tagging and the feeders were readjusted. Water temperatures were adjusted 

periodically to reflect temperatures at Cougar Reservoir. Tanks were cleaned three times a week and 

examined daily on weekdays for shed tags. Transmitter messages were recorded with an Advanced 

Telemetry Systems model Trident SR5000 receiver (ATS; Isanti, Minnesota) and processed as other 

autonomous receivers. Data were summarized using Kaplan-Meier survivorship analysis (Hosmer and 

Lemeshow, 1999). 

Results

The estimated lives of the acoustic transmitters tested were as expected. The median life of the 

transmitters was 142.9 days, and the maximum life was 157.6 days (fig. C1). The first tag stopped 

working after 89.9.0 days and the 90th percentile of tag life was 131.0 days. The estimated 90th 

percentile of tag life was used as the follow-up period. 
63 

Figure C1. Graph of the survival distribution function of days from activation to expiration for acoustic transmitters 

tested as part of the study at Cougar Reservoir, Oregon, 2015–16.

None of the fish expelled either the PIT or acoustic tag during the evaluation through 240 and 

225 days post-tagging for the September 14 and 29 tagging dates, respectively. There were no 

mortalities during the study. The mean fork length of fish tagged on September 14, 2014, was 123.99 

mm (range 104–139 mm), whereas the mean size of fish tagged on September 29, 2014, was 123.8 mm

(range 110–151 mm) (table C1). Tag burden was similar between both tagging groups at about 2.5 

percent (range 1.4–3.9 percent) (table C1). A subsample of fish from each tank was netted, anesthetized, 

and weighed, and fork length was measured intermittently during the study (table C2). At sample days 

84 and 99 since surgery, the fish weight had doubled in weight. By the final sample dates (>217 days 

from surgery), fish length had nearly doubled and fish weight had increased more than fivefold. Moving 

the surgical incision location adjacent to, rather than on, the mid-ventral line in water temperatures 

observed at Cougar Reservoir reduced acoustic and PIT tag loss to zero in juvenile Chinook salmon for 

at least 217 days, well past the expected tag life in this study. 

Table C1. Summary statistics at tagging of fork length (millimeters), weight (grams), and percent tag burden of 

acoustic +PIT-tagged hatchery Chinook salmon by tag date during the tag life and transmitter retention study, 

2015–16. 

[N, number of fish; SD, standard deviation]

Tag date N Fork length Weight Percent tag burden

Mean SD Range Mean SD Range Mean SD Range

September 14 50 123.9 8.4 104–139 22.5 4.8 13.6–32.4 2.5 0.6 1.6–3.9

September 29 50 123.8 9.7 110–151 21.8 5.2 14.3–37.3 2.6 0.6 1.4–3.7
64 

Table C2. Summary statistics at tagging of fork length (millimeters) and weight (grams) of acoustic +PIT-tagged 

hatchery Chinook salmon by tag date, tank, and subsample date during the tag life and transmitter retention study, 

2015–16. 

[Weight is the weight of the fish minus the weight of the implanted tags. Fish size data were omitted from two north fish on 

the final sample date 225 days since surgery. N, number of fish; min, minimum; max, maximum] 

Days since 

surgery

N Mean fork length

(min–max)

Mean weight

(min–max) N Mean fork length(min–max)

Mean weight

(min–max)

9/14/15 Tank 1 9/14/15 Tank 2

0 25 123.0 (104 – 135) 21.9 (14.0 – 30.8) 25 124.8 (107 – 139) 23.1 (13.6 – 32.4)

60 4 151.5 (146 – 155) 41.2 (35.5 – 47.7) 6 145.8 (127 – 157) 38.2 (27.8 – 48.2)

99 5 158.6 (150 – 162) 55.1 (47.5 – 60.3) 7 159.3 (144 – 173) 58.3 (37.2 – 79.6)

178 7 193.3 (175 – 224) 104.7 (71.4 – 163.1) 5 176.4 (165 – 200) 78.4 (58.3 – 129.1)

233 11 207.5 (180 – 260) 125.3 (76.6 – 247.2) 10 205.2 (177 – 239) 127.5 (75.0 – 203.2)

240 12 216.5 (186 – 237) 132.4 (73.8 – 163.8) 15 211.1 (184 – 243) 126.1 (77.0 – 194.6)

9/29/15 Tank 1 9/29/15 Tank 2

0 25 122.8 (110 – 151) 21.4 (14.3 – 37.3) 25 124.8 (112 – 145) 22.3 (15.1 – 34.3)

45 9 147.2 (130 – 165) 38.5 (23.8 – 50.8) 7 143.6 (131 – 159) 35.6 (25.7 – 49.5)

84 9 154.2 (129 – 174) 52.9 (30.8 – 71.7) 7 152.4 (130 – 165) 51.5 (28.0 – 71.0)

163 8 186.9 (150 – 210) 92.5 (45.0 – 119.4) 8 162.8 (140 – 174) 61.5 (36.1 – 80.4)

218 14 187.9 (164 – 211) 90.9 (56.4 – 144.6) 15 195.0 (173 – 229) 107.2 (72.2 – 169.4)

225 11 219.5 (184 – 253) 140.2 (83.0 – 217.6) 10 206.9 (166 – 240) 111.3 (53.7 – 181.2)
65 

Appendix D. Positioning System Accuracy

Introduction

It is important to estimate location estimation errors from positioning systems so the resulting 

data can be placed in proper context relative to the objectives of the study. For this study, our goal was 

to estimate positions of acoustic+PIT-tagged fish over a large area near the portable floating fish 

collector (PFFC) and temperature control tower at Cougar Dam (the cul-de-sac) and to have position 

accuracies within about 1 m of the true position near the entrance to the PFFC and within a few meters 

of the true position throughout the rest of the monitored area. This goal was determined by U.S. 

Geological Survey and U.S. Army Corps of Engineers staff to meet the study objectives. Location 

estimation errors also were used to estimate Utilization Distributions (see section, “Spatial Intensity of 

Use”). 

Methods

Accuracies of the fish positions determined from the juvenile salmon acoustic telemetry system 

(JSATS) cabled systems in the cul-de-sac were determined from empirical estimates of system accuracy 

based on test tags. Tag data came from tags with 5-second pulse rate intervals towed by a remotecontrolled boat and stationary tags affixed to the PFFC or to floating platforms. Fifteen tags towed by 

the boat were grouped in pairs or triplets and suspended below the surface of the water at approximately 

1.83-m intervals 1.83–9.84 m deep while the boat moved throughout the monitored area at a rate of 

about 0.3 m/s. The boat path was restricted by the series of JSATS communication cables and PFFC 

anchor lines. Locations of the four stationary tags included carbon-fiber poles at each side of the PFFC 

entrance and at two floating platforms about 20 m upstream of the PFFC; each tag was mounted 11 m 

below the water surface. The x-y positions of test tags were determined with Javad GNSS® antennas 

collecting data directly over the tags every second and were compared to data from the JSATS system at 

the nearest time. Spatially explicit system errors in the x-y (horizontal) plane were estimated as the 

absolute difference between the positions estimated using the acoustic telemetry system and the Global 

Positioning System. Errors in the z (vertical) plane were estimated as the absolute difference between 

the known depths and those estimated using the acoustic telemetry system. The spatially explicit 

position errors were assigned to the fish positions using the Kriging process and were used in estimates 

of the intensity of fish use within the area monitored in the cul-de-sac (see Methods section, “Spatial 

Intensity of Use”). Temperature variance by depth was averaged hourly to determine a single speed of 

sound in water per hour that is used to calculate the positions of the acoustic transmitters. 

Results

The accuracy of the estimated fish positions varied spatially and ranged from less than 1 m to 

more than 10 m. Accuracy within the hydrophone array was consistently greater than outside the array, 

as expected based on hydrophone geometry (Pincock and Johnston, 2012; fig. D1). Estimated position 

accuracies within the hydrophone array in the x-y and z planes generally were about 1–2 m. The 

estimated system accuracies within the bounds of the hydrophone array met the stated goal. 
66 

Figure D1. Graphs of the estimated position accuracies (in meters [m]) of the acoustic telemetry system in the 

horizontal (graphs A, C) and vertical (graphs B, D) planes in the cul-de-sac of Cougar Reservoir, Oregon, 2015–16. 

Graphs A and B represent data collected August 26–27, 2015, and are plotted at 1,572 feet, and graphs C and D 

represent data collected November 16–17, 2015, and are plotted at 1,555 feet (the mean water elevation for the 

data collection periods). The portable floating fish collector (PFFC) is shown near the center of each graph and the 

water temperature control tower is at the top center of each graph. Gray circles indicate the positions of the 

hydrophones.
67 

Appendix E. Summary of Portable Floating Fish Collector Operating Conditions Collected by U.S. Army 

Corps of Engineers Staff at Cougar Reservoir and Dam, Oregon, 2015–16

Table E1. Means of observed portable floating fish collector (PFFC) operation and environmental data collected by U.S. Army Corps of Engineers

staff by treatment and block at Cougar Reservoir and Dam, Oregon, 2015–16. 

[Tower, water temperature control tower. Number of observations is the number of times U.S. Army Corps of Engineers staff recorded data during each 

treatment and block. °C, degrees Celsius; ft3

/s, cubic foot per second; mg/L, milligram per liter; NA, not applicable; ND, no data]

Block Treatment

Percent 

attraction 

pump

Leveling 

pump

(inches)

Distance 

from 

tower 

(feet)

Mean 

observed 

reservoir 

elevation

(feet)

Water 

temperature

(°C)

Dissolved 

oxygen 

(percent)

Dissolved 

oxygen 

(mg/L)

Number of 

observations

Mean dam 

discharge

(ft3/s)

1 High 95 96.0 72.0 1552.4 ND ND ND 4 327.3

1 Low 50 95.7 67.0 1553.9 ND ND ND 3 343.4

2 High 95 98.5 70.2 1557.3 ND ND ND 5 339.2

2 Low 50 100.0 60.8 1564.1 9.6 ND ND 4 337.9

3 High 95 96.4 65.1 1578.4 9.3 ND ND 8 324.4

3 Low 50 100.0 60.0 1571.4 9.8 ND ND 4 322.5

4 High 95 95.0 60.6 1590.7 11.2 ND 10.7 5 331.6

4 Low 50 95.0 55.3 1585.4 10.7 ND 10.8 7 330.8

5 High 95 95.0 50.3 1596.9 13.7 ND 11.0 4 300.9

5 Low 50 95.0 61.8 1594.7 13.1 ND 10.9 5 317.7

6 High 95 95.0 59.0 1600.5 13.9 ND 10.6 6 304.0

6 Low 50 95.0 51.0 1598.7 14.1 ND 9.8 4 301.0

7 Low 50 95.0 59.3 1602.8 16.3 ND ND 4 308.3

8 Low 50 108.0 54.0 1603.1 19.3 ND 9.1 4 399.4

15 High 95 95.0 58.8 1576.3 16.5 ND 9.5 6 328.9

15 Low 50 96.8 55.2 1573.8 16.5 ND 9.3 6 329.8

16 High 95 98.0 54.0 1570.8 15.1 ND 9.5 6 329.4

16 Low 50 101.0 53.0 1567.1 14.9 ND 9.7 6 378.6

17 High 95 100.0 53.0 1562.6 14.5 ND 9.8 3 412.5

17 Low 50 100.0 52.2 1559.3 14.3 ND 9.8 5 352.0
68 

Block Treatment

Percent 

attraction 

pump

Leveling 

pump

(inches)

Distance 

from 

tower 

(feet)

Mean 

observed 

reservoir 

elevation

(feet)

Water 

temperature

(°C)

Dissolved 

oxygen 

(percent)

Dissolved 

oxygen 

(mg/L)

Number of 

observations

Mean dam 

discharge

(ft3/s)

18 High 95 100.0 51.0 1556.5 12.2 95.3 10.3 6 330.4

18 Low 50 101.0 51.0 1556.8 13.4 ND 10.1 7 324.5

19 High 95 100.0 54.8 1561.0 10.0 93.4 ND 6 727.3

19 Low 50 100.0 51.0 1555.0 11.1 94.4 ND 5 339.6

20 High 95 100.0 54.0 1556.0 8.3 91.8 ND 5 1270.6

20 Low 50 100.0 47.3 1538.0 7.6 92.0 ND 4 1223.5

21 High 95 100.0 67.2 1550.6 7.3 90.4 ND 6 1857.6

21 Low 50 100.7 70.5 1555.4 6.4 92.0 ND 5 2334.5

22 High 95 100.0 57.8 1557.1 5.8 90.8 ND 4 2742.3

22 Low 50 101.8 54.6 1536.5 5.6 86.5 ND 5 987.7

23 High 95 103.0 60.0 1536.4 5.0 90.5 ND 6 1009.6

23 Low 50 103.0 56.3 1534.3 5.1 87.8 ND 5 544.7

24 High 95 100.0 56.4 1534.0 5.7 95.0 ND 5 2455.1

24 Low 50 105.0 60.8 1542.3 5.6 93.5 ND 4 1948.6

NA High 95 100.0 65.9 1528.0 6.2 94.6 ND 17 1625.1
69 

Appendix F. Comparison of Temperature Profiles Across the Cul-de-Sac at 

Cougar Reservoir and Dam, Oregon, 2015–16

Introduction

As we assessed fish utilization and distribution with the cul-de-sac, we began to question if there 

was a temperature difference within the cul-de-sac and across the array owing to the influence of Rush 

Creek, anomalous hydrodynamics, or modified operations due to incomplete reservoir filling and if the 

temperature string at the water temperature control tower (tower) represented the temperatures at various 

locations within the acoustic telemetry array. 

Methods

To determine if there was variation in water temperature across the array, we constructed four 

temperature strings. Each string consisted of a rope to which we attached an Onset HOBO Tidbit® v2 

(Onset; Cape Cod, Massachusetts) water temperature data logger at 1, 3, 5, 10, 15, and 20 m from the 

water surface. We then deployed the strings at four locations within the cul-de-sac (fig. F1). Each 

location was monitored with a Global Positioning System antenna used for determining the surface 

elevation of the forebay and, thus, the data logger elevation. Each data logger was configured to sample 

hourly and was downloaded periodically to verify functionality. 

Figure F1. Photograph showing locations of temperature strings and approximate distances to the water 

temperature control tower temperature string in the cul-de-sac at Cougar Reservoir, Oregon, 2015. Photograph by 

Scott D. Evans, U.S. Geological Survey, August 6, 2015. Rush Creek is in the upper center of the photograph and 

the portable floating fish collector (PFFC) is in the center of the photograph. 
70 

We selected 4:00 p.m. on the 21st day of each month as a representative period for comparison 

of data among the locations. The data were plotted to compare temperature at depth for each temperature 

string data logger. Two adjustments were made to reduce interference of temperature strings and 

hydrophone guide cables. The Tidbit® string nearest the tower (2 m) was removed after about two weeks 

of monitoring because of interference with the barge guide cables, the tower temperature string, and 

potential entrainment into a trash rack on the tower. The farthest string (85 m) also did not have a logger 

at 20 m depth to prevent entanglement on the shoreline as the reservoir elevation was reduced. 

Results

Temperatures across the cul-de-sac varied very little, although there was some variation between 

the tower temperature string and the Tidbit® string when there were greater temperature variations for 

the representative day. In August, September, and October the tower temperature varied slightly (1–2 

°C) at some of the depths when the temperature profile varied (4–14 °C). In November, December, and 

January, there was almost no difference in the string temperatures, and differences for the whole 

temperature profile was less than 1 °C (fig. F2). In conclusion, there was little difference in the 

horizontal cul-de-sac water temperatures at the measured locations during the 2015–16 study. 
71 

Figure F2. Temperature at depth comparisons for all locations at 4:00 p.m. on a representative day in each month 

of deployment in the cul-de-sac of Cougar Reservoir, Oregon, 2015–16. PFFC is the portable floating fish collector.
72 

Appendix G. Graphs of Utilization Distributions Overlap Indices Comparing 

Utilization Distributions of Acoustic+Passive Integrated Transponder-Tagged 

Juvenile Chinook Salmon in the Cul-de-Sac of Cougar Reservoir and Dam, 

Oregon, 2015–16

Figure G1. Graphs of utilization distribution overlap indices (UDOIs) for monthly comparisons among utilization 

distributions (95th percentile, red lines; 50th percentile, black lines) of acoustic+PIT-tagged juvenile Chinook 

salmon by treatment, diel period, and depth at Cougar Reservoir, Oregon, September 2015–January 2016. Strata 

include Low and High treatments, Day and Night diel periods, and 0–3, 3–6, 6–9, 9–12, and 12–15 meter depth 

bins. 
73 

Figure G2. Graphs of utilization distribution overlap indices (UDOIs) for comparisons of utilization distributions 

(95th percentile, red lines; 50th percentile, black lines) of acoustic+PIT-tagged juvenile Chinook salmon between 

treatments by diel period and depth strata at Cougar Reservoir, Oregon, September 2015–January 2016. Strata 

include Day and Night diel periods, and 0–3, 3–6, 6–9, 9–12, and 12–15 meter depth bins.
74 

Figure G3. Graphs of utilization distribution overlap indices (UDOIs) for comparisons of utilization distributions 

(95th percentile, red lines; 50th percentile, black lines) of acoustic+PIT-tagged juvenile Chinook salmon between 

diel periods by treatment and depth strata at Cougar Reservoir, Oregon, September 2015–January 2016. Strata 

include Low and High treatments and 0–3, 3–6, 6–9, 9–12, and 12–15 meter depth bins.
75 

Appendix H. Utilization Distributions from Acoustic+Passive Integrated 

Transponder-Tagged Juvenile Chinook Salmon in the Cul-de-Sac of Cougar 

Reservoir and Dam, Oregon, 2015–16

Figure H1. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) Low treatment, day, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, September 2015.
76 

Figure H2. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) Low treatment, night, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, September 2015.
77 

Figure H3. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) High treatment, day, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, September 2015.
78 

Figure H4. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) High treatment, night, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, September 2015.
79 

Figure H5. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon, at five depth bins during the 

condition of portable floating fish collector (PFFC) Low treatment, day, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, October 2015.
80 

Figure H6. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) Low treatment, night, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, October 2015.
81 

Figure H7. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) High treatment, day, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, October 2015.
82 

Figure H8. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) High treatment, night, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, October 2015.
83 

Figure H9. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during the 

condition of portable floating fish collector (PFFC) Low treatment, day, in the cul-de-sac of Cougar Reservoir and 

Dam, Oregon, November 2015.
84 

Figure H10. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) Low treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, November 2015.
85 

Figure H11. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, day, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, November 2015.
86 

Figure H12. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, November 2015.
87 

Figure H13. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) Low treatment, day, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, December 2015. 
88 

Figure H14. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) Low treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, December 2015.
89 

Figure H15. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, day, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, December 2015.
90 

Figure H16. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, December 2015.
91 

Figure H17. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) Low treatment, day, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, January 2016.
92 

Figure H18. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) Low treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, January 2016.
93 

Figure H19. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, day, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, January 2016.
94 

Figure H20. Utilization distributions from acoustic+PIT-tagged juvenile Chinook salmon at five depth bins during 

the condition of portable floating fish collector (PFFC) High treatment, night, in the cul-de-sac of Cougar Reservoir 

and Dam, Oregon, January 2016.
95 

Appendix I. Rose Diagrams of Mean Fish Travel Directions at the Portable 

Floating Fish Collector at Cougar Dam, Oregon, 2015–16

Figure I1. Rose diagrams showing mean bearings of acoustic+PIT-tagged juvenile Chinook salmon in front of the 

portable floating fish collector (PFFC) entrance at 0–3 meter depths during the day, Cougar Reservoir, 2015–16.

Figure parts A–J and K–T (indicated in the upper right corner of each part) show the Low and High treatment, 

respectively. Points on the plot circumferences are mean bearings for each fish and are stacked when multiple fish 

have the same bearing. Sample sizes are indicated in the lower left corner of each figure part, and the results of 

Moore’s second–order test of uniformity are given in the lower right corner for sample sizes greater than 9 (U, 

hypothesis of uniform distribution accepted; NU, hypothesis of uniform distribution rejected; A, hypothesis of 

uniformity rejected, axial distribution).
96 

Figure I2. Rose diagrams showing mean bearings of acoustic+PIT-tagged juvenile Chinook salmon in front of the 

portable floating fish collector (PFFC) entrance at 0–3 meter depths during the night, Cougar Reservoir, 2015–16.

Figure parts A–J and K–T (indicated in the upper right corner of each part) show the Low and High treatment, 

respectively. Points on the plot circumferences are mean bearings for each fish and are stacked when multiple fish 

have the same bearing. Sample sizes are indicated in the lower left corner of each figure part, and the results of 

Moore’s second–order test of uniformity are given in the lower right corner for sample sizes greater than 9 (U, 

hypothesis of uniform distribution accepted; NU, hypothesis of uniform distribution rejected; A, hypothesis of 

uniformity rejected, axial distribution).
97 

Figure I3. Rose diagrams showing mean bearings of acoustic+PIT-tagged juvenile Chinook salmon in front of the 

portable floating fish collector (PFFC) entrance at 3–6 meter depths during the day, Cougar Reservoir, 2015–16.

Figure parts A–J and K–T (indicated in the upper right corner of each part) show the Low and High treatment, 

respectively. Points on the plot circumferences are mean bearings for each fish and are stacked when multiple fish 

have the same bearing. Sample sizes are indicated in the lower left corner of each figure part, and the results of 

Moore’s second–order test of uniformity are given in the lower right corner for sample sizes greater than 9 (U, 

hypothesis of uniform distribution accepted; NU, hypothesis of uniform distribution rejected; A, hypothesis of 

uniformity rejected, axial distribution).
98 

Figure I4. Rose diagrams showing mean bearings of acoustic+PIT-tagged juvenile Chinook salmon in front of the 

portable floating fish collector (PFFC) entrance at 3–6meter depths during the night, Cougar Reservoir, 2015–16.

Figure parts A–J and K–T (indicated in the upper right corner of each part) show the Low and High treatment, 

respectively. Points on the plot circumferences are mean bearings for each fish and are stacked when multiple fish 

have the same bearing. Sample sizes are indicated in the lower left corner of each figure part, and the results of 

Moore’s second–order test of uniformity are given in the lower right corner for sample sizes greater than 9 (U, 

hypothesis of uniform distribution accepted; NU, hypothesis of uniform distribution rejected; A, hypothesis of 

uniformity rejected, axial distribution).
Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

 Director, Western Fisheries Research Center

U.S. Geological Survey

6505 NE 65th Street

Seattle, Washington 98115 

http://wfrc.usgs.gov/
ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20161197

Beeman and others—Evaluation of the Performance of the Portable Floating Fish Collector at Cougar Dam, Oregon—Open-File Report 2016–1197