Evaluation of Juvenile Salmonid Behavior Near a Prototype 

Weir Box at Cowlitz Falls Dam, Washington, 2013

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2014–1042
Cover: Photographs showing Cowlitz Falls Dam and the prototype weir box (inset).

Photographs taken by John Serl, Washington Department of Fish and Wildlife.
Evaluation of Juvenile Salmonid Behavior Near a 

Prototype Weir Box at Cowlitz Falls Dam, Washington,

2013

By Tobias J. Kock, Theresa L. Liedtke, Brian K. Ekstrom, Ryan G. Tomka, and Dennis W. Rondorf

Open-File Report 2014–1042

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, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014 

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Suggested citation:

Kock, T.J., Liedtke, T.L., Ekstrom, B.K., Tomka, R.G., and Rondorf, D.W., 2014, Evaluation of juvenile salmonid 

behavior near a prototype weir box at Cowlitz Falls Dam, Washington, 2013: U.S. Geological Survey Open-File

Report 2014-1042, 24 p., http://dx.doi.org/10.3133/ofr20141042. 

ISSN 2331-1258 (online)

Any use of trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this information product, for the most part, is in the public domain, it also may contain

copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be 

secured from the copyright owner.
iii

Contents

Executive Summary.................................................................................................................................................... 1

Introduction................................................................................................................................................................. 3

Methods...................................................................................................................................................................... 4

Fish Collection, Tagging, and Release.................................................................................................................... 4

Monitoring Array...................................................................................................................................................... 5

Data Analysis .......................................................................................................................................................... 5

Reservoir Travel Times and Forebay Residence Times......................................................................................5

Behavior Near Collection Entrances....................................................................................................................6

Passage Routes and Fish Collection through the Flumes and Weir Box.............................................................6

Results........................................................................................................................................................................ 6

Reservoir Travel Times and Forebay Residence Times ......................................................................................... 6

Behavior Near Collection Entrances ....................................................................................................................... 7

Passage Routes and Fish Collection through the Flumes and Weir Box ................................................................ 7

Discussion .................................................................................................................................................................. 8

Acknowledgments..................................................................................................................................................... 10

References Cited...................................................................................................................................................... 10

Appendix A. Summary of Individual Detection Histories of Juvenile Steelhead during a Radiotelemetry 

Evaluation at Cowlitz Falls Dam, 2013 ..................................................................................................................... 17

Appendix B. Summary of Individual Detection Histories of Juvenile Coho Salmon during a Radiotelemetry 

Evaluation at Cowlitz Falls Dam, 2013 ..................................................................................................................... 21

Figures

Figure 1. Schematic of Cowlitz Falls Dam showing the locations of baffle panels, spillbays, and 

collection flumes ...................................................................................................................................................... 12

Figure 2. River flows passed through turbines (black line) and spillbays (gray line) at Cowlitz Falls Dam 

during April–July 2013 ............................................................................................................................................. 13

Figure 3. Schematic of underwater antenna locations in and around the fish collection system at Cowlitz Falls 

Dam, 2013 ............................................................................................................................................................... 14

Figure 4. Schematic of the multistate model that was used to estimate the probability of tagged fish

being collected through the collection flumes and weir box at Cowlitz Falls Dam, 2013......................................... 15

Tables

Table 1. Summary of release dates, number of fish released, and average sizes of fish released during a 

radiotelemetry evaluation at Cowlitz Falls Dam, 2013 ............................................................................................. 15

Table 2. Summary of the number of fish released and detected at specific locations within the study area 

along with travel times, forebay residence times, and passage routes used during the study ................................. 16

Table 3. Estimates from a multistate model for detection probabilities and proportion of tagged fish collected 

through the weir box and collection flumes, 2013.................................................................................................... 16
iv

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

Flow rate

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

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

Inch-pound to SI

Multiply By To obtain

Flow rate

cubic foot per second (ft3/s) 3.281 foot per second (ft/s) 
1

Evaluation of Juvenile Salmonid Behavior Near a 

Prototype Weir Box at Cowlitz Falls Dam, Washington,

2013

By Tobias J. Kock, Theresa L. Liedtke, Brian K. Ekstrom, Ryan G. Tomka, and Dennis W. Rondorf

Executive Summary

Collection of juvenile salmonids at Cowlitz Falls Dam is a critical part of the effort to restore 

salmon in the upper Cowlitz River because the majority of fish that are not collected at the dam pass 

downstream and enter a large reservoir where they become landlocked and lost to the anadromous fish 

population. However, the juvenile fish collection system at Cowlitz Falls Dam has failed to achieve 

annual collection goals since it first began operating in 1996. Since that time, numerous modifications to 

the fish collection system have been made and several prototype collection structures have been 

developed and tested, but these efforts have not substantially increased juvenile fish collection. Studies 

have shown that juvenile steelhead (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and 

Chinook salmon (Oncorhynchus tshawytscha) tend to locate the collection entrances effectively, but 

many of these fish are not collected and eventually pass the dam through turbines or spillways. Tacoma 

Power developed a prototype weir box in 2009 to increase capture rates of juvenile salmonids at the 

collection entrances, and this device proved to be successful at retaining those fish that entered the weir. 

However, because of safety concerns at the dam, the weir box could not be deployed near a spillway 

gate where the prototype was tested, so the device was altered and re-deployed at a different location, 

where it was evaluated during 2013. The U.S. Geological Survey conducted an evaluation using 

radiotelemetry to monitor fish behavior near the weir box and collection flumes. 

The evaluation was conducted during April–June 2013. Juvenile steelhead and coho salmon (45 

per species) were tagged with a radio transmitter and passive integrated transponder (PIT) tag, and 

released upstream of the dam. All tagged fish moved downstream and entered the forebay of Cowlitz 

Falls Dam. Median travel times from the release site to the forebay were 0.8 d for steelhead and 1.2 d 

for coho salmon. Most fish spent several days in the dam forebay; median forebay residence times were 

4.4 d for juvenile steelhead and 5.7 d for juvenile coho salmon. A new radio transmitter model was used 

during the study period. The transmitter had low detection probabilities on underwater antennas located 

within the collection system, which prevented us from reporting performance metrics (discovery 

efficiency, entrance efficiency, retention efficiency) that are traditionally used to evaluate fish collection 

systems. 
2

Most tagged steelhead (98 percent) and coho salmon (84 percent) were detected near the weir 

box or collection flume entrances during the study period; 39 percent of tagged steelhead and 55 percent 

of tagged coho salmon were detected at both entrances. Sixty-three percent of the tagged steelhead that 

were detected at both entrances were first detected at the weir box, compared to 52 percent of the coho 

salmon. Twelve steelhead and 15 coho salmon detected inside the weir box eventually left the device 

and were collected in collection flumes or passed the dam. Overall, collection rates were relatively high 

during the study period. Sixty-five percent of the steelhead and 80 percent of the coho salmon were 

collected during the study, and most of the remaining fish passed the dam and entered the tailrace (24 

percent of steelhead; 13 percent of coho salmon). The remaining 11 percent of steelhead and 7 percent 

of coho salmon did not pass the dam while their transmitters were operating. 

We were able to confirm collection of tagged fish at the fish facility using three approaches: (1) 

detection of radio transmitters in study fish; (2) detection of PIT-tags in study fish; (3) observation of 

study fish by staff at the fish facility. Data from all three methods were used to develop a multistate 

mark-recapture model that estimated detection probabilities for the various monitoring methods. These 

estimates then were used to describe the percent of tagged fish that were collected through the weir box 

and collection flumes. Detection probabilities of PIT-tag antennas in the collection flumes were 0.895 

for juvenile steelhead and 0.881 for juvenile coho salmon, although radiotelemetry detection 

probabilities were 0.654 and 0.646 for the two species, respectively. The multistate model estimates 

showed that all steelhead and most coho salmon (94.5 percent) that were collected at the dam entered 

the collection system through the flumes rather than through the weir box. None of the tagged steelhead 

and only 5.5 percent of the tagged coho salmon were collected through the weir box. These data show 

that juvenile steelhead and coho salmon collection rates were much higher through the collection flumes 

than through the weir box. 

Low detection probabilities of tagged fish in the fish collection system resulted in uncertainty for 

some aspects of our evaluation. Missing detection records within the collection system for fish that were 

known to have been collected resulted in four tagged steelhead and seven tagged coho salmon being 

removed from the dataset, which was used to assess discovery rates of the weir box and collection 

flumes. However, the multistate model allowed us to provide unbiased estimates of the percentage of 

tagged fish that were collected through each route, and these data showed that few fish were collected 

through the weir box. 

Overall, the fish collection system performed reasonably well in collecting juvenile steelhead 

and coho salmon during the 2013 collection season. Fish collection efficiency estimates from the 

Washington Department of Fish and Wildlife showed that steelhead collection efficiency was slightly 

higher than the 10-year average (46 percent compared to 42 percent), whereas coho salmon collection 

efficiency was more than twice as high as the 10-year average (63 percent compared to 30 percent). 

However, the performance of the weir box was poor because most fish were collected through the 

collection flumes. 
3

Introduction

Surface collection systems can increase survival for juvenile salmonids at dams, but to be 

effective they must collect a large proportion of the population because fish that are not collected will 

pass through other routes where injury or death can occur. Most dams provide multiple passage routes

(for example, collection systems, turbines, spillways) for juvenile fish migrating downstream. Juvenile 

salmonids rely on factors, such as water velocity and turbulence, to guide downstream movements, so 

routes that pass large volumes of water are highly effective at passing fish (Coutant, 2001; Tiffan and 

others, 2009). Surface collection systems are effective because juvenile salmonids typically migrate near 

the surface, but these systems must create conditions in a dam forebay that are conducive to discovery, 

entry, and retention (Coutant and Whitney, 2000; Adams and others, 2001; Johnson and Dauble, 2006; 

Evans and others, 2008). Otherwise, the risk of passing through alternate routes is greatly increased. 

The surface collection system at Cowlitz Falls Dam is known to attract juvenile salmonids 

effectively under a variety of configurations, but rejection of the collection system entrances is common, 

and this factor is largely responsible for the failure of the system to meet annual collection goals. 

Juvenile salmonids that arrive at Cowlitz Falls Dam are either collected or they pass the dam and enter 

Riffe Lake. Fish that are collected are transported via tanker truck downstream around the Cowlitz River 

hydrosystem and released into a series of stress-relief ponds from which they can volitionally enter the 

free-flowing river and migrate to the ocean. With the exception of fish that are collected through 

supplemental methods, fish that enter Riffe Lake become landlocked and are lost to the anadromous 

population. Studies have shown that discovery rates of the surface collection system routinely exceed 90 

percent at Cowlitz Falls Dam (Hausmann and others, 2001; Farley and others, 2003; Liedtke and others, 

2009). However, mark-recapture findings indicate that only about 50 percent of juvenile steelhead

(Oncorhynchus mykiss), 21 percent of juvenile coho salmon (Oncorhynchus kisutch), and 20 percent of 

juvenile Chinook salmon (Oncorhynchus tshawytscha) were collected annually during 1996–2012 (Serl 

and Heimbigner, 2013). In 2003, Perry and others (2004) used radiotelemetry and an acoustic camera to 

monitor fish behavior within 1 m of the flume entrances at Cowlitz Falls Dam. They reported that “at 

most only 25 percent of the fish that come within 1 m of the flume entrances subsequently pass into the 

entrance” (Perry and others, 2004). These studies have shown that most fish locate collection entrances 

but many reject entering the collection system and eventually pass the dam and enter Riffe Lake. The 

high rejection rates are the factor that is limiting the collection system from achieving annual collection 

goals, so recent attempts to improve collection at the dam have focused on improving entry and 

retention rates of the collection entrances.

Tacoma Power developed and tested two prototype fish collection devices at Cowlitz Falls Dam 

during 2006–2010 in an attempt to improve annual fish collection efficiencies. The first device was a 

fish screen that was designed as a single collection entrance that attached to collection flume 3 and 

extended upstream 12.2 m to baffle panel 3 (fig. 1; Liedtke and others, 2010). The fish screen was 

designed with a 6.1-m wide, 6.1-m deep entrance that gradually narrowed in the downstream direction 

to provide uniform water acceleration (0–2.1 m/s), which has been an important factor in optimizing 

surface collection of juvenile fish (Haro and others, 1998). The second device was a weir box that was

designed as a wide (8.5 m), shallow (0.6 m) structure that attached at the upstream entrance to collection 

flumes 1 and 2, inside spillbay 2 (fig. 1; Liedtke and others, 2010). The weir box created a wide, 

shallow flow field that spilled over the weir crest and captured smolts in a high flow, turbulent holding 

box where they were susceptible to entrainment in collection flumes. In 2009, the fish screen and weir 

box were evaluated simultaneously during a radiotelemetry evaluation in which 318 juvenile coho 

salmon and 317 juvenile Chinook salmon were monitored. Discovery efficiencies of the fish screen and 

weir box by juvenile salmonids were similar for each species (about 80 percent for coho salmon; about 
4

60 percent for Chinook salmon) but capture efficiencies were substantially higher for the weir box 

(Liedtke and others, 2010). For coho salmon, the capture efficiency of the weir box was 93 percent, 

whereas the capture efficiency of the fish screen was 16 percent (Liedtke and others, 2010). This 

relationship was similar for Chinook salmon, as capture efficiencies of the weir box were 91 percent 

compared to 38 percent for the fish screen (Liedtke and others, 2010). Given these findings, the weir 

box appeared to be a promising option for improving capture efficiencies, and thereby increasing fish 

collection at Cowlitz Falls Dam.

In 2013, Tacoma Power developed a plan to install and evaluate a weir box during the peak 

outmigration period for juvenile steelhead and coho salmon at Cowlitz Falls Dam. The deployment 

location and size of the weir box differed from when the device was tested during 2009 because of dam 

safety concerns that disallowed deployment in the original location. During 2013, the weir box was 

deployed at baffle panel 3, and the overall width of the device was reduced from 8.5 to 6.1 m (fig. 1). A 

weir crest was located on the upstream side of the device, and water depths over the crest were 0.15–

0.30 m. The evaluation plan, which was developed by Tacoma Power, consisted of using three 

approaches to determine the performance of the device: (1) quantitative fish capture data would be 

collected by monitoring relatively large numbers of fish tagged with passive integrated transponders 

(PIT-tags; 500–1,000 fish per species) in the weir box, in collection flumes, and in the fish facility; (2) 

hydraulic data would be collected throughout the evaluation to determine if flow-related performance 

trends were apparent; and (3) qualitative fish behavior data would be collected by monitoring radiotagged fish (45 fish per species). Fieldwork was scheduled to be conducted during mid-April to lateJune, and Tacoma Power was responsible for conducting the PIT-tag and hydraulic measurement 

components, and the U.S. Geological Survey was responsible for conducting the radiotelemetry 

component of the evaluation. This report summarizes findings from the radiotelemetry evaluation. 

Methods

Fish Collection, Tagging, and Release

Juvenile steelhead and coho salmon were collected and tagged with a radio transmitter and a 

PIT-tag at the Cowlitz Falls Dam fish facility during 2013. Fish were collected and held for 24 h prior to 

tagging. A total of 90 fish (45 steelhead; 45 coho salmon) were tagged and released during the study 

(table 1; fig. 2). Three releases were made for each species, and release groups ranged from 8 to 23 fish 

per group (table 1). Radio transmitters (Model NTQ-2; Lotek© Wireless Inc.; Newmarket, Ontario, 

Canada) weighed 0.30 g (in air) and had an expected operating life of 23 d. Fish weights ranged from 

8.9 to 115.2 g (table 1), so the weight of the transmitter comprised 0.3–3.4 percent of the individual 

body weights of fish in our study. Transmitters were surgically implanted using methods described by 

Liedtke and others (2012). During each surgical procedure, a PIT-tag (Model HPT12 12.5 mm 134.2 

kHz ISO FDXB; Biomark©, Inc.; Boise, Idaho) and a radio transmitter were implanted into the body 

cavity of individual fish . After tagging, fish were held for approximately 24 h prior to release to 

monitor short-term mortality related to the handling and tagging process. Tagged fish were then 

transported and released at the Cowlitz Falls Day Use Park, located 3.9 rkm upstream of the dam. 
5

Monitoring Array

During 2013, juvenile salmonids could be collected at Cowlitz Falls Dam through collection 

flumes in spillbay 2 (above turbine 1) or through the weir box in spillbay 3 (above turbine 2; fig. 1). The 

primary objectives of our monitoring effort were to describe fish behavior near the collection flumes 

and weir box and to quantify tagged fish that entered through these routes. To accomplish these 

objectives, we operated a single telemetry receiver that monitored 22 underwater antennas located in 

and around the collection system. These antennas were grouped at several areas to create a series of 

detection zones (fig. 3). A pair of antennas were grouped immediately upstream of the weir box to 

create the weir box discovery zone that detected tagged fish within 4.6 m of the weir box entrance (fig. 

3). Inside the weir box, a pair of antennas were grouped to detect tagged fish that entered the device.

These antennas were attenuated to ensure that fish were not detected upstream of the weir box entrance.

The areas near baffle panels 1 and 2 were monitored with one antenna each and comprised the discovery 

zones of those two areas, respectively (fig. 3). The entrances to flumes 1 and 2, and the area 

immediately downstream of the entrances, were monitored with two antennas each, creating the 

discovery zones of those areas. The weir box and flume discovery zones were important areas for 

monitoring fish behavior because detection within these zones confirmed that individual tagged fish had 

discovered a collection entrance. The four additional zones, downstream of the collection entrances, 

were used to confirm fish collection passage routes (fig. 3). We also used PIT-tag detectors located 

immediately downstream of collection flumes 1 and 2, and in the fish collection system to confirm that 

individual fish had been collected. Finally, staff from the fish facility visually assessed collected fish for 

the presence of a radio transmitter and when observed, the fish was scanned with a PIT-tag reader to 

obtain the individual fish identification data. 

We also operated three fixed monitoring sites upstream of the dam and two fixed sites 

downstream of the dam to collect additional information on the movement of tagged fish. The most 

upstream site was located at the Lewis County Public Utility District (LCPUD) boat launch, 1.3 rkm 

upstream of the dam, and the remaining sites were located on Cowlitz Falls Dam and monitored the 

forebay for tagged fish. Fixed monitoring sites were located 0.2 and 4.8 rkm downstream of the dam to 

detect fish that passed Cowlitz Falls Dam and entered Riffe Lake.

Data Analysis

Reservoir Travel Times and Forebay Residence Times

We calculated reservoir travel times and forebay residence times for tagged fish as basic 

descriptors of fish movement patterns following release. Although these metrics provide little 

information that could be useful for assessing how the weir box and fish collection flumes performed 

during 2013, they do provide a measure of comparing fish behavior among years to determine if 

behavior patterns were consistent with those observed during previous studies. Reservoir travel times 

were calculated by subtracting the date and time of release from the first date and time of detection in 

the forebay of Cowlitz Falls Dam. Forebay residence times were calculated by subtracting the first date 

and time of detection from the last date and time of detection in the forebay of Cowlitz Falls Dam.
6

Behavior Near Collection Entrances

We analyzed telemetry detection records near collection entrances to describe four measures that 

were used for assessing the performance of the collection entrances. Evaluations of fish collection 

devices generally report performance metrics such as discovery efficiency, entrance efficiency, and 

retention efficiency. However, tag performance issues during our study precluded us from presenting 

these metrics. Therefore, we used the following measures: (1) number of tagged fish that were detected 

within 4.6 m of the weir box and collection flume entrances; (2) which collection entrance was first 

discovered by individual fish that encountered both entrances; (3) number of trips individual fish made 

to each collection entrance; and (4) number of fish that entered an entrance but later exited and were 

detected elsewhere in the forebay. Data from the two collection flumes in spillbay 2 were pooled for 

these analyses. 

Passage Routes and Fish Collection through the Flumes and Weir Box

We used a multistate mark-recapture model to obtain unbiased estimates of collection numbers 

through each passage route. Tagged fish that entered the collection system could be observed through 

detection of a radio transmitter, detection of a PIT-tag, or visually observed by fish facility staff when 

fish were being processed for transportation downstream. Observations from each method were pooled, 

and these data were used to develop a multistate model that provided unbiased estimates of the

proportions of tagged fish that were collected through each route. The multistate model (Perry and 

others, 2012; fig. 4) included six parameters; four parameters represented detection probabilities within 

the collection system, and two parameters represented the estimated proportion of tagged fish collected 

through the collection flumes and weir box (fig. 4; table 3). The detection probability parameters were: 

• pf1, probability of a fish being detected on PIT-tag antennas in the collection flumes; 

• pf2, probability of a fish being detected on radiotelemetry antennas in the collection flumes; 

• pw, probability of a fish being detected on radiotelemetry antennas in the weir box; and 

• pc, probability of a fish being detected on PIT-tag antennas or observed by fish facility staff in 

the collection facility. 

The passage route parameters were: 

• Cf, proportion of tagged fish that were collected through the collection flumes; and 

• Cwb, proportion of tagged fish that were collected through the weir box. 

Results

Reservoir Travel Times and Forebay Residence Times

All tagged steelhead and coho salmon moved downstream of the release site and entered the 

forebay of Cowlitz Falls Dam during the study period. Median travel times from the release site to the 

forebay were 0.8 d for steelhead and 1.2 d for coho salmon (table 2; appendixes A and B). Travel times 

ranged from 0.2 d (4.3 h) to 18.7 d for steelhead and from 0.3 d to 19.9 d for coho salmon. Median 

forebay residence times for steelhead were 4.4 d compared to 5.7 d for coho salmon. Three coho salmon 

and two steelhead spent less than 1 h in the forebay; the remaining forebay residence times ranged from 

approximately 1 h to 36.9 d for steelhead and 42.5 d for coho salmon (table 2).
7

Behavior Near Collection Entrances

Detection probabilities were low for some of the radio transmitters used on underwater antennas 

located in the collection system, so a subset of the detection records were used to determine discovery 

rates and behavior patterns near the collection entrances. Although we detected every tagged fish on 

aerial antennas during the study period, some of the transmitters were not detected on underwater 

antennas when it was known that specific fish were present in monitored locations. Four tagged 

steelhead and seven tagged coho salmon were collected at the fish facility, but were not detected on 

underwater antennas located in and around the collection system. These fish were removed from 

analyses related to behavior patterns near the collection entrances to reduce bias associated with poor 

transmitter performance. By removing these fish, we were left with detection histories for 41 steelhead 

and 38 coho salmon (table 2). 

Nearly all steelhead and coho salmon used in behavioral analyses were detected near at least one 

of the collection entrances during the study period. Forty steelhead (98 percent) and 32 coho salmon (84 

percent) were detected within 3 m of the flumes or weir box while in the forebay (table 2; appendixes 

A–B). Thirty-nine percent of the steelhead and 55 percent of the coho salmon were detected within 3 m 

of both collection devices. Of the steelhead that were detected near both entrances, 63 percent were first 

detected at the weir box entrance compared to 37 percent at the flume entrances. For coho salmon, the 

pattern of first detections was nearly equal between the two collection locations (52 percent at the weir 

box; 48 percent at the flumes; table 2). Fish that were detected near collection entrances usually made 

multiple trips to these locations. Tagged steelhead averaged 4.2 trips (range = 1–15) to the weir box and 

3.7 trips (range = 1–16) to the flumes during their forebay residence time, and coho salmon averaged 

3.9 trips (range = 1–9) to the weir box and 3.7 trips (range = 1–10) to the flumes. Thirty-four steelhead 

(83 percent) and 24 coho salmon (63 percent) were detected at the weir box entrance during the study 

period. 

We did not observe tagged steelhead or coho salmon rejecting the collection flumes once they 

entered through those routes, but a substantial number of steelhead (12 fish; 27 percent) and coho 

salmon (15 fish; 33 percent) were known to have been inside the weir box and not collected. These fish 

entered the weir box and then moved out of the device and were later collected through the flumes or 

passed the dam and entered the tailrace.

Passage Routes and Fish Collection through the Flumes and Weir Box

A high proportion of tagged steelhead and coho salmon were collected during our study period. 

Sixty-five percent of the steelhead and 80 percent of the coho salmon were collected at the fish facility

(table 2). Tagged fish that were not collected either passed the dam (24 percent of steelhead; 13 percent 

of coho salmon) or remained upstream of the dam (11 percent of steelhead; 7 percent of coho salmon) 

(table 2; appendixes A–B) during the period when their radio transmitters were operating.

Estimates from the multistate model indicated that detection probabilities of radio-tagged fish 

were low and that tagged coho salmon and steelhead primarily were collected through the flumes rather 

than through the weir box. Detection probabilities for PIT-tags in collection flumes were 0.895 for 

steelhead and 0.881 for coho salmon, which were higher than for radio transmitters (0.654 for steelhead; 

0.646 for coho salmon; table 3). Detection probabilities for tagged fish in the collection facility were 

high (0.964 for steelhead; 0.971 for coho salmon; table 3). Estimates from the multistate model showed 

that all steelhead and 94.5 percent of the coho salmon were collected through the collection flumes 

(table 3).
8

Discussion

The fish collection system at Cowlitz Falls Dam performed reasonably well during the 2013 fish

collection season, although collection of juvenile salmonids through the weir box was low. We observed 

that 65 percent of the tagged steelhead and 80 percent of the tagged coho salmon from our study were 

collected. Tacoma Power’s PIT-tag study was conducted across a broader time scale than our study, and 

preliminary results from their research support the assertion that overall fish collection was reasonable 

in 2013. Their estimates suggest that 49 percent of the steelhead and 71 percent of the coho salmon were 

collected (Matt Bleich, Tacoma Power, written commun., 2013). By comparison, average collection 

rates from 2003 to 2012 were 46 percent for steelhead and 30 percent for coho salmon (Serl and 

Heimbigner, 2013). Although collection rates were at or above average in 2013, the weir box made a 

minimal contribution to collection success. Discovery rates of the weir box were fairly high, as 83 

percent of the steelhead and 63 percent of the coho salmon were detected near the weir box entrance.

Tagged fish also made repeated trips between the weir box and collection flumes. However, none of the 

tagged steelhead, and a few coho salmon (5.5 percent), were collected through the device. Rejection 

rates at the weir box were apparently high, based on detections of tagged fish inside the weir box that 

were subsequently followed by detections at other locations in the forebay. These findings show that the 

configuration of the collection system in 2013 resulted in similar issues to those which have previously 

been observed at Cowlitz Falls Dam. Reasonable numbers of fish discovered the collection entrances. 

but low capture efficiencies resulted in many fish passing the dam rather than being collected.

Our study was limited by low detection probabilities of tagged fish on underwater antennas in 

the collection system. In previous studies at Cowlitz Falls Dam, detection probabilities on underwater 

antennas typically exceeded 95 percent. However, the transmitters used for this study were a relatively 

new model that had not been previously tested on the monitoring system used to monitor underwater 

antennas at the dam. Detections on aerial antennas located upstream of the dam, in the forebay, and 

downstream of the dam were consistent with previous studies (Kock and others, 2007; Liedtke and 

others, 2007; Kock and others, 2012), but detections on underwater antennas within the system were 

lower than observed in the past. Study transmitters were originally purchased for the 2012 fish 

collection season, but were not used that year because high debris loads at the dam precluded operating 

the device during most of the 2012 fish collection season. Therefore, the transmitters were more than 1-

year old when they were used for the 2013 evaluation. The signal output of individual transmitters was 

highly variable when monitored prior to tagging, which may explain why some transmitters provided 

the anticipated high detections whereas other transmitters did not. Another possible contributor to the 

low detections is the PIT-tag information system, which was new during 2013. It is possible that this

new system introduced some level of electronic interference with our monitoring array that may have 

negatively affected detection probabilities. However, we conducted pre-season and in-season testing 

with two randomly selected transmitters, and found that detection probabilities of those transmitters

within the system were consistent with previous evaluations. 

The multistate model allowed us to provide unbiased estimates of collection proportions through 

the flumes and weir box. Detection probabilities (0.654 for steelhead and 0.646 for coho salmon) for 

radiotelemetry antennas located downstream of the flume entrances showed that one in every three 

tagged fish were not detected when they entered the collection system. Study fish also were PIT-tagged, 

and detection probabilities for PIT-tag antennas located near the telemetry antennas were 0.895 for 

steelhead and 0.881for coho salmon. These estimates showed that telemetry antennas did not detect 

about one-third of the tagged fish, whereas PIT-tag antennas did not detect about 10 percent of the study 

fish at this location. The combination of monitoring techniques located in the collection facility itself 

was less than perfect. Tagged fish in the fish facility were identified by PIT-tag antennas or by facility 
9

staff at a rate of 0.964 for steelhead and 0.971 for coho salmon. Because a small percentage (3–4 

percent) of study fish were not identified in the collection facility, collection estimates from the 

collection facility alone would have underestimated the true collection rate. These observations 

demonstrate how redundancy in monitoring systems can be beneficial in areas where less than perfect 

detection probabilities can occur. Finally, collection estimates from the multistate model showed that 

nearly all study fish collected during 2013 entered the collection system through the collection flumes 

rather than the weir box.

The performance of the weir box during 2013 was substantially different than the performance 

of the weir box in 2009. During 2009, 81 percent of the coho salmon were detected near the weir box 

entrance, but the discovery rate during 2013 (63 percent) was substantially lower (Liedtke and others, 

2010). The most promising aspect of the weir box’s performance in 2009 was the retention efficiency; 

93 percent of the coho salmon and 91 percent of the Chinook salmon that entered the device were 

collected (Liedtke and others, 2010). However, of the 12 steelhead and 17 coho salmon that entered the 

device during 2013, all steelhead and most of the coho salmon (88 percent) eventually left and passed 

the dam through another route. Although the weir box was conceptually similar between years, the 

device was structurally different and was operated at different locations. In 2009, the weir box was 8.5 

m wide and attached directly to both flumes in spillbay 2; during 2013, the device was narrowed to 6.1 

m wide and was deployed 12.2 m upstream of collection flume 3, at the entrance to spillbay 3. These 

alterations apparently had a major effect on fish response. Although the 2009 evaluation suggested that 

the device was a promising concept for increasing capture efficiencies at Cowlitz Falls Dam, the 

performance of the weir box during 2013 indicated that the device collected few fish during steelhead 

and coho salmon evaluations. 

Results from this study can help inform decisions regarding future collection efforts at Cowlitz 

Falls Dam. The overall fish collection system performance in 2013 was slightly above average for 

steelhead and more than double the average for coho salmon, but this was mostly due to capture through 

the collection flumes rather than capture through the weir box. Another variable to consider when 

observing increased collection in 2013 is trash rack cleaning by LCPUD prior to the fish collection 

season. The prototype weir box was not tested as expected in 2012 because debris occluded much of the 

trash rack on the intake of turbine 2. This changed intake flow, which in turn negatively affected the 

weir box, and created an unsafe dam operating environment in certain conditions. As a result, the tests 

were terminated. Provisions were made to remove most of the debris, and weir box prototype tests 

resumed in 2013 during the steelhead and coho salmon season. Collection success at Cowlitz Falls Dam 

is inversely related to river flows (John Serl, Washington Department of Fish and Wildlife, oral 

commun., 2013) but our study did not allow for these comparisons because of our small sample sizes.

The radiotelemetry data provided information on fish behavior, but the larger PIT-tag study may be 

insightful for determining if the performance of the collection system was influenced by river flows. 

Collectively, the two studies should provide information that can be used to direct future efforts aimed

at improving fish collection at Cowlitz Falls Dam.
10

Acknowledgments

This study was made possible by the efforts and collaboration of multiple people who 

represented numerous agencies. We thank Tacoma Power for providing the funding for this research, 

along with PIT-tag detection data that were used in our analyses. John Serl and his staff at the Cowlitz 

Falls facility collected fish for tagging and monitored collected fish daily to identify study fish that were 

collected; their efforts are greatly appreciated. Joe First and his staff at Cowlitz Falls Dam provided 

access and support required for the installation and maintenance of our equipment during the study 

period. 

References Cited

Adams, N.S., Johnson, G.E., Rondorf, D.W., Anglea, S.M., and Wik, T., 2001, Biological evaluation of 

the behavioral guidance structure at Lower Granite Dam on the Snake River, Washington in 1998: 

American Fisheries Society Symposium, v. 26, p. 145–160. 

Coutant, C.C., and Whitney, R.R., 2000, Fish behavior in relation to passage through hydropower 

turbines—A review: Transactions of the American Fisheries Society, v. 129, p. 351–380. 

Coutant, C.C., 2001, Turbulent attraction flows for guiding juvenile salmonids at dams: American 

Fisheries Society Symposium, v. 26, p. 55–57. 

Evans, S.D., Adams, N.S., Rondorf, D.W., Plumb, J.M., and Ebberts, B.D., 2008, Performance of a 

prototype surface collector for juvenile salmonids at Bonneville Dam’s first powerhouse on the 

Columbia River, Oregon: River Research and Applications, v. 24, p. 960–974. 

Farley, J.M., Perry, R.W., Shurtleff, D.J., Feil, D.H., and Rondorf, D.W., 2003, Migration behavior of 

juvenile salmonids and evaluation of a modified flume entrance at Cowlitz Falls Dam, Washington, 

2001: Report by the U.S. Geological Survey to the Public Utility District No. 1 of Lewis County, 

51 p. 

Haro, A., Odeh, M., Noreika, J., and Castro-Santos, T., 1998, Effect of water acceleration on 

downstream migratory behavior and passage of Atlantic salmon juvenile salmonids and juvenile 

American shad at surface bypasses: Transactions of the American Fisheries Society, v. 127, 

p. 118–127. 

Hausmann, B.J., Feil, D.H., and Rondorf, D.W., 2001, Evaluation of an experimental baffle panel 

configuration to improve fish collection efficiency at Cowlitz Falls Dam, Washington, spring 2000: 

Report by the U.S. Geological Survey to the Public Utility District No. 1 of Lewis County, 16 p. 

Johnson, G.E., and Dauble, D.D., 2006, Surface flow outlets to protect juvenile salmonids passing 

through hydropower dams: Reviews in Fisheries Science, v. 14, p. 213–244. 

Kock, T.J., Liedtke, T.L., Ekstrom, B.K., Tomka, R.G., and Rondorf, D.W., 2012, Behavior and passage 

of juvenile salmonids during evaluation of a behavioral guidance structure at Cowlitz Falls Dam, 

Washington, 2011: U.S. Geological Survey Open-File Report 2012–1030, 96 p., 

http://pubs.usgs.gov/of/2012/1030/. 

Kock, T.J., Liedtke, T.L., Kritter, M.A., and Rondorf, D.W., 2007, Behavior and passage of juvenile 

salmonids during evaluation of a new fish screen at Cowlitz Falls Dam, 2006: Report by the U.S. 

Geological Survey to Tacoma Power, 46 p. 

Liedtke, T.L., Beeman, J.W., and Gee, L.P., 2012, A standard operating procedure for the surgical 

implantation of transmitters in juvenile salmonids: U.S. Geological Survey Open-File Report 2012-

1267, 50 p., http://pubs.usgs.gov/of/2012/1267/. 
11

Liedtke, T.L., Kock, T.J., Ekstrom, B.K., and Rondorf, D.W., 2009, Behavior and passage of juvenile 

salmonids during the evaluation of a fish screen at Cowlitz Falls Dam, Washington, 2008: Report by 

the U.S. Geological Survey to Tacoma Power, 33 p. 

Liedtke, T.L., Kock, T.J., Ekstrom, B.K., Royer, I.M., and Rondorf, D.W., 2010, Juvenile salmonid 

collection efforts in the upper Cowlitz River basin—2009 evaluations: Report by the U.S. Geological 

Survey to Tacoma Power, 135 p. 

Liedtke, T.L., Kock, T.J., Kritter, M.A., Ekstrom, B.K., and Rondorf, D.W., 2007, Behavior and 

passage of juvenile salmonids during evaluation of a fish screen at Cowlitz Falls Dam, 2007: Report 

by the U.S. Geological Survey to Tacoma Power, 49 p. 

Perry, R.W., Braatz, A.C., Farley, M.J., and Rondorf, D.W., 2004, Migration behavior of juvenile 

salmonids and evaluation of a modified box entrance at Cowlitz Falls Dam, Washington, 2003: 

Annual report by the U.S. Geological Survey and Washington Department of Fish and Wildlife to 

Lewis County PUD, 57 p. 

Perry, R.W., Castro-Santos, T., Holbrook, C.M., and Sandford, B.P., 2012, Using mark-recapture 

models to estimate survival from telemetry data, in Adams, N.S., Beeman, J.W., and Eiler, J.H., eds., 

Telemetry Techniques—A User Guide for Fisheries Research: Bethesda, Maryland, American 

Fisheries Society, p. 453–475. 

Serl, J.D., and Heimbigner, D., 2013, Data summary for the 2012 operation of the Cowlitz Falls fish 

facility and related activities: Report by the Washington Department of Fish and Wildlife and the 

Pacific States Marine Fisheries Commission to the Bonneville Power Administration, 51 p. 

Tiffan, K.G., Kock, T.J., Haskell, C.A., Connor, W.P., and Steinhorst, R.K., 2009, Water velocity, 

turbulence, and migration rate of subyearling fall Chinook salmon in the free-flowing and impounded 

Snake River: Transactions of the American Fisheries Society, v. 138, p. 373–384. 
12

Figure 1. Schematic of Cowlitz Falls Dam showing the locations of baffle panels, spillbays, and collection flumes.

Debris

barrier

Flow

1 2 3 4

1 2 3 4

1 2 3 4

Baffle panels

Collection flumes

Spillbays
13

Figure 2. River flows passed through turbines (black line) and spillbays (gray line) at Cowlitz Falls Dam during 

April–July 2013. Bars show the number of radio-tagged juvenile steelhead (black bars) and juvenile coho salmon 

(gray bars) that were released on specific days during the study period.

Date

4/21/13 

5/5/13 

5/19/13 

6/2/13 

6/16/13 

6/30/13 

7/14/13 

Flow (ft

3/sec)

0

2000

4000

6000

8000

10000

12000

14000

Number of fish

0

5

10

15

20

25

30
14

Figure 3. Schematic of underwater antenna locations in and around the fish collection system at Cowlitz Falls 

Dam, 2013.

Weir box

Baffle Weir box discovery zone

panel

1 and 2 

discovery 

zones

Flume

1 and 2 

discovery 

zones
15

 

Figure 4. Schematic of the multistate model that was used to estimate the probability of tagged fish being collected 

through the collection flumes and weir box at Cowlitz Falls Dam, 2013.

Table 1. Summary of release dates, number of fish released, and average sizes of fish released during a 

radiotelemetry evaluation at Cowlitz Falls Dam, 2013.

[Numbers in parentheses are one standard deviation from the mean]

Species Release date

Number of fish 

released Weight (g) Fork length (mm)

Steelhead 4/30/2013 14 65.3 (17.9) 191.0 (14.7)

Steelhead 5/17/2013 8 48.9 (10.3) 173.8 (12.9)

Steelhead 5/24/2013 23 55.6 (10.6) 182.7 (12.4)

Totals 45 57.4 (14.3) 183.7 (14.3)

Coho salmon 5/17/2013 16 16.9 (3.7) 115.1 (9.9)

Coho salmon 6/7/2013 15 24.7 (4.3) 133.6 (6.6)

Coho salmon 6/12/2013 14 24.9 (4.5) 134.0 (6.8)

Totals 45 21.9 (5.6) 127.1 (11.9)

State 2

weir

box

State 1

collection

flumes

Fish

facility

PIT-tag detection

Observation by fish facility staff

(Cwb) (Cf)

Radio transmitter

detection

(pw)

PIT-tag detection

(pf1 Radio transmitter )

detection

(pf2)

(pc)

Forebay
16

Table 2. Summary of the number of fish released and detected at specific locations within the study area along with 

travel times, forebay residence times, and passage routes used during the study.

Descriptor Steelhead Coho salmon

Travel Time and Forebay Residence

Number of fish released 45 45

Median travel time from release to forebay 0.8 d (range = 0.2–18.7 d) 1.2 d (range = 0.3–19.9 d)

Number of fish that arrived in the forebay 45 (100 percent) 45 (100 percent)

Median residence time in forebay 4.4 d (range = <1 h–36.9 d) 5.7 d (range = <1 h–42.5 d)

Near-Dam Behavior

Number of fish with unreliable near-dam detections 4 7

Number of fish with reliable near-dam detections 41 38

Number of fish detected at weir box or flumes 40 (98 percent) 32 (84 percent)

Number of fish detected at weir box and flumes 16 (39 percent) 21 (55 percent)

Number of fish detected first at weir box (if detected 

at both locations)

10 (63 percent) 11 (52 percent)

Number of fish detected first at flumes (if detected at 

both locations)

6 (37 percent) 10 (48 percent)

Dam Passage

Number of fish collected 29 (65 percent) 36 (80 percent)

Number of fish passed into tailrace 11 (24 percent) 6 (13 percent)

Number of fish that didn’t pass dam 5 (11 percent) 3 (7 percent)

Table 3. Estimates from a multistate model for detection probabilities and proportion of tagged fish collected 

through the weir box and collection flumes, 2013.

[Numbers in parentheses are standard errors]

Parameter Descriptor Steelhead Coho salmon

pf1 Detection probability of radio-tagged fish in collection flumes 0.654 (0.088) 0.646 (0.082)

pf2 Detection probability of PIT-tagged fish in collection flumes 0.895 (0.057) 0.881 (0.056)

pw Detection probability of radio-tagged fish in weir box 1.000 1.000

pc Detection probability of PIT-tagged fish in collection facility 0.964 (0.035) 0.971 (0.028)

Cf Proportion of fish collected through collection flumes 1.000 0.945 (0.038)

Cwb Proportion of fish collected through weir box 0.000 0.055 (0.038)
17

Appendix A. Summary of Individual Detection Histories of Juvenile Steelhead during a Radiotelemetry 

Evaluation at Cowlitz Falls Dam, 2013

[To conserve space only the last 7 digits of each PIT-tag code are reported. The first 7 digits (3D9.1C2) were identical for all fish. Fates were assigned as flumes 

or weir box if fish were collected through a known route, otherwise collected fish were assigned a fate of the fish facility (CFFF). Fish that passed the dam were 

assigned a tailrace fate. Bold date/time values identify which collection device was first encountered for fish detected at the flumes and weir box] 

 

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of first 

detection at 

weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

1027 E0B32A1 4/30/13 

12:39

4/30/13 

17:35 0.2 CFFF 5/3/2013 0/0 5/19/2013 

03:58 18.4

1028 E0A3DD4 4/30/13 

12:39

5/02/13 

05:24 1.7 FLUMES 5/5/2013 5/03/13 09:22

5/03/13 

08:32 2/4 5/05/2013 

02:41 2.9

1030 E0B4F9C 4/30/13 

12:39

4/30/13 

16:55 0.2 FLUMES 5/5/2013 5/01/13 

05:21

5/01/13 

14:53 6/6 5/05/2013 20:27 5.1

1039 E0A70C7 4/30/13 

12:39

4/30/13 

20:29 0.3 FLUMES 5/3/2013 5/02/13 15:10 0/1 5/03/2013 14:19 2.7

1015 E0AF440 4/30/13 

12:39

5/01/13 

00:00 0.5 DID NOT PASS

5/04/13 

21:26

5/04/13 

20:13 1/1 5/06/2013 

14:59 5.6

1036 E0AE1A5 4/30/13 

12:39

5/08/13 

19:36 8.3 DID NOT PASS 0/0 5/09/2013 02:24 0.3

1037 E0B472C 4/30/13 

12:39

5/19/13 

05:14 18.7 DID NOT PASS 0/0 5/24/2013 03:39 4.9

1011 E0A27CA 4/30/13 

12:39

4/30/13 

17:21 0.7 TAILRACE 5/7/2013 5/01/13 

05:25

5/01/13 

20:26 8/7 5/07/2013 23:23 7.3

1012 DF7D602 4/30/13 

12:39

5/19/13 

01:26 18.5 TAILRACE 6/3/2013 0/0 5/19/2013 01:29 0.0

1013 E0A343A 4/30/13 

12:39

5/01/13 

03:33 0.6 TAILRACE 5/5/2013 5/03/13 14:22

5/02/13 

19:55 1/1 5/04/2013 

23:28 3.8

1016 E0A4AA9 4/30/13 

12:39

5/02/13 

00:43 1.5 TAILRACE 5/5/2013 5/02/13 11:32 2/0 5/05/2013 11:03 3.4
18

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of first 

detection at 

weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

1026 E0ADFA8 4/30/13 

12:39

4/30/13 

18:54 0.3 TAILRACE 5/8/2013 5/01/13 

01:47

5/01/13 

20:38 6/7 5/07/2013 23:39 7.2

1038 E0A4687 4/30/13 

12:39

4/30/13 

19:07 0.3 TAILRACE 5/1/2013 0/0 5/01/2013 01:29 0.3

1040 E0B06AB 4/30/13 

12:39

4/30/13 

17:15 0.2 TAILRACE 5/7/2013 5/02/13 

14:40

5/02/13 

19:49 6/6 5/07/2013 

21:09 7.2

1018 E0B5860 5/17/13 

09:59

5/18/13 

04:28 0.8 CFFF 5/22/2013 0/0 5/20/2013 12:38 2.3

1019 E0A98F3 5/17/13 

09:59

5/18/13 

01:50 0.7 CFFF 5/22/2013 0/0 5/22/2013 02:08 4.0

1020 E0B527B 5/17/13 

09:59

5/18/13 

02:39 0.7 CFFF 5/21/2013 5/20/13 

18:00

5/20/13 

22:27 1/1 5/21/2013 08:26 3.2

1032 E0ACEC7 5/17/13 

09:59

5/17/13 

18:47 0.4 CFFF 5/21/2013 5/17/13 23:07 0/1 5/20/2013 01:34 2.3

1025 E0B4D6C 5/17/13 

09:59

5/18/13 

07:37 0.9 FLUMES 5/28/2013 5/19/13 

04:25

5/19/13 

04:28 9/8 5/27/2013 15:20 9.3

1033 E0A9916 5/17/13 

09:59

5/17/13 

16:37 0.3 FLUMES 5/18/2013 5/17/13 

17:05

5/17/13 

17:52 2/2 5/18/2013 00:39 0.3

1031 E0A3239 5/17/13 

09:59

5/18/13 

05:35 0.8 DID NOT PASS

5/18/13 

05:35

5/18/13 

06:12 12/9 5/25/2013 15:54 7.4

1042 E0A81F9 5/17/13 

09:59

5/18/13 

04:39 0.8 DID NOT PASS 0/0 5/18/2013 04:44 0.0

2055 E0A83E6 5/24/13 

09:11

5/25/13 

11:44 1.1 CFFF 5/30/2013 0/0 5/30/2013 01:59 4.6

2056 E0A5AB7 5/24/13 

09:11

5/25/13 

04:22 0.8 CFFF 6/4/2013 0/0 6/03/2013 03:43 9.0

2057 E0B5BBA 5/24/13 

09:11

5/24/13 

23:32 0.6 CFFF 6/2/2013 0/0 6/01/2013 11:45 7.5

2069 E0B5DEE 5/24/13 

09:11

5/25/13 

09:43 1.0 CFFF 5/26/2013 0/0 5/26/2013 21:25 1.5
19

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of first 

detection at 

weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

2072 E0A5ADB 5/24/13 

09:11

5/25/13 

00:44 0.6 CFFF 5/28/2013 0/0 5/27/2013 

21:07 2.8

2048 E0B3E84 5/24/13 

09:11

5/25/13 

03:49 0.8 FLUMES 6/14/2013 6/06/13 02:33 0/5 6/14/2013 02:02 19.9

2051 E0B1521 5/24/13 

09:11

5/24/13 

22:24 0.6 FLUMES 6/2/2013 5/25/13 

06:49

5/25/13 

16:45 3/5 6/01/2013 09:46 7.5

2053 DF7AFFB 5/24/13 

09:11

5/27/13 

16:20 3.3 FLUMES 5/30/2013 5/29/13 03:13 0/2 5/30/2013 02:16 2.4

2059 E0A9B22 5/24/13 

09:11

5/25/13 

03:09 0.7 FLUMES 6/4/2013 5/25/13 

16:14

5/30/13 

11:41 9/7 6/02/2013 11:01 8.3

2061 DF7D690 5/24/13 

09:11

5/25/13 

03:40 0.8 FLUMES 5/27/2013 5/25/13 17:26

5/25/13 

15:55 1/2 5/26/2013 

14:09 1.4

2062 E0A690A 5/24/13 

09:11

5/26/13 

08:57 2.0 FLUMES 5/30/2013 5/29/13 07:50

5/26/13 

16:40 1/2 5/29/2013 

16:53 3.3

2063 E0B19C3 5/24/13 

09:11

5/26/13 

02:03 1.7 FLUMES 5/31/2013 5/27/13 

03:39

5/27/13 

03:51 5/2 5/31/2013 02:30 5.0

2064 E0AD3F1 5/24/13 

09:11

5/25/13 

09:22 1.0 FLUMES 5/30/2013 5/25/13 

09:22

5/29/13 

18:19 1/1 5/29/2013 18:27 4.4

2065 E0B0B30 5/24/13 

09:11

5/26/13 

00:43 1.6 FLUMES 5/31/2013 5/26/13 

04:33

5/27/13 

14:42 3/3 5/30/2013 10:14 4.4

2067 E0AF60C 5/24/13 

09:11

5/25/13 

18:31 1.4 FLUMES 5/26/2013 5/26/13 

14:26

5/26/13 

14:32 1/1 5/26/2013 14:32 0.8

2070 DF7CBA6 5/24/13 

09:11

5/24/13 

14:49 0.2 FLUMES 5/31/2013 5/24/13 14:59

5/24/13 

14:55 15/16 5/30/2013 

22:06 6.3

2071 E0A9E30 5/24/13 

09:11

5/25/13 

10:49 1.1 FLUMES 5/31/2013 5/25/13 

12:09

5/25/13 

19:29 1/2 5/28/2013 10:55 3.0

2073 E0B14DE 5/24/13 

09:11

5/26/13 

11:55 2.1 FLUMES 5/26/2013 5/26/13 

12:55

5/26/13 

16:40 2/2 5/26/2013 

20:59 0.4

2074 DF7A2CB 5/24/13 

09:11

5/26/13 

12:31 2.1 FLUMES 6/17/2013 6/08/13 11:28 0/2 6/15/2013 10:17 19.9
20

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of first 

detection at 

weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

2046 E0AEF84 5/24/13 

09:11

5/26/13 

01:39 1.7 TAILRACE 5/30/2013 5/26/13 11:28 0/2 6/15/2013 00:57 20.0

2049 E0AE745 5/24/13 

09:11

5/25/13 

10:46 1.1 TAILRACE 7/1/2013 0/0 7/01/2013 08:20 36.9

2066 E0A763A 5/24/13 

09:11

5/26/13 

07:50 1.9 TAILRACE 5/28/2013 5/26/13 

11:28

5/27/13 

18:37 3/1 6/13/2013 02:30 17.8

2068 E0A4B6A 5/24/13 

09:11

5/26/13 

08:35 2.0 TAILRACE 5/28/2013 5/26/13 

13:42

5/26/13 

14:48 4/3 5/28/2013 19:14 2.4
21

Appendix B. Summary of Individual Detection Histories of Juvenile Coho Salmon during a 

Radiotelemetry Evaluation at Cowlitz Falls Dam, 2013 

[To conserve space only the last 7 digits of each PIT-tag code are reported. The first 7 digits (3D9.1C2) were identical for all fish. Fates were assigned as flumes 

or weir box if fish were collected through a known route; otherwise collected fish were assigned a fate of the fish facility CFFF. Fish that passed the dam were 

assigned a tailrace fate. Bold date/time values identify which collection device was first encountered for fish detected at the flumes and weir box] 

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of 

first 

detection 

at weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

1017 E0BD6AB 5/17/13 

09:59

5/23/13 

14:38 6.2 CFFF 5/28/2013 0/0 5/28/2013 

07:43 4.7

1022 E0AFDF6 5/17/13 

09:59

6/05/13 

01:28 18.6 CFFF 6/7/2013 6/05/13 06:07

6/05/13 

05:48 3/3 6/08/2013 

03:18 3.1

1029 E0AE8C3 5/17/13 

09:59

5/20/13 

16:19 3.3 CFFF 5/31/2013 0/0 5/30/2013 14:03 9.9

1035 E0A5B12 5/17/13 

09:59

5/19/13 

04:48 1.8 CFFF 5/26/2013 5/21/13 09:43

5/21/13 

09:24 1/1 5/26/2013 

04:14 7.0

2044 E0AFD62 5/17/13 

09:59

5/18/13 

02:49 0.7 CFFF 7/2/2013 5/18/13 

07:53

5/18/13 

20:02 8/7 6/29/2013 13:56 42.5

2054 E0B59E7 5/17/13 

09:59

5/21/13 

20:51 4.5 CFFF 6/2/2013 0/0 5/31/2013 19:05 9.9

1021 E0A3C27 5/17/13 

09:59

5/17/13 

18:06 0.3 FLUMES 5/23/2013 5/19/13 

15:43

5/19/13 

18:56 5/4 5/23/2013 20:33 6.1

1023 E0B46E5 5/17/13 

09:59

5/18/13 

14:18 1.2 FLUMES 5/20/2013 5/20/13 01:25

5/18/13 

20:05 1⁄2 5/20/2013 

03:03 1.5

1041 E0B3756 5/17/13 

09:59

5/18/13 

01:39 0.7 FLUMES 5/25/2013 5/19/13 

09:58

5/19/13 

20:05 7/7 5/25/2013 16:50 7.6

2045 E0AF91D 5/17/13 

09:59

5/19/13 

04:14 1.8 FLUMES 5/29/2013 5/21/13 10:55 0/1 5/28/2013 09:50 9.2

2047 E0A83CA 5/17/13 

09:59

5/18/13 

02:32 0.7 FLUMES 6/6/2013 5/19/13 12:18 0/3 6/01/2013 07:00 14.2

2050 E0A9EA8 5/17/13 

09:59

5/17/13 

21:13 0.5 FLUMES 5/18/2013 5/17/13 

21:59

5/18/13 

08:36 1/1 5/18/2013 13:10 0.7
22

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of 

first 

detection 

at weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

2052 E0A64BE 5/17/13 

09:59

5/18/13 

04:08 0.8 FLUMES 5/27/2013 5/18/13 17:50

5/18/13 

17:29 8/8 5/26/2013 

16:54 8.5

2058 E0ABCD6 5/17/13 

09:59

5/18/13 

00:41 0.6 FLUMES 5/22/2013 5/21/13 

14:02 0/1 5/22/2013 

03:26 4.1

2060 E0B575C 5/17/13 

09:59

5/18/13 

15:42 1.2 FLUMES 5/30/2013 5/18/13 

15:42

5/20/13 

14:32 3/3 5/29/2013 13:45 10.9

1034 DF7C85E 5/17/13 

09:59

6/06/13 

07:27 19.9 TAILRACE 6/7/2013 6/06/13 07:31 1/0 6/07/2013 01:57 0.8

3075 E0A9E53 6/07/13 

10:18

6/09/13 

17:23 2.3 CFFF 6/17/2013 6/10/13 05:40 0/3 6/15/2013 10:56 5.7

3078 E0B359E 6/07/13 

10:18

6/08/13 

00:53 0.6 CFFF 6/13/2013 6/09/13 03:39 0/3 6/13/2013 07:08 5.3

3086 E0A3FA4 6/07/13 

10:18

6/09/13 

15:22 2.2 CFFF 6/16/2013 0/0 6/15/2013 11:28 5.8

3076 E0A901C 6/07/13 

10:18

6/08/13 

08:16 0.9 FLUMES 6/10/2013 6/09/13 23:19 0/1 6/10/2013 00:24 1.7

3088 E0B195B 6/07/13 

10:18

6/07/13 

19:41 0.4 FLUMES 6/22/2013 6/07/13 

23:58

6/08/13 

03:29 7/6 6/21/2013 18:05 13.9

3090 E0AC943 6/07/13 

10:18

6/08/13 

01:23 0.6 FLUMES 6/12/2013 6/09/13 

06:22

6/09/13 

06:50 4/5 6/11/2013 10:23 3.4

3095 E0AB331 6/07/13 

10:18

6/09/13 

07:03 1.9 FLUMES 6/14/2013 6/09/13 08:57 0/2 6/13/2013 14:05 4.3

3098 E0B175A 6/07/13 

10:18

6/09/13 

01:28 1.6 FLUMES 6/11/2013 6/11/13 16:58 0/1 6/11/2013 16:58 2.6

3103 E0B54A7 6/07/13 

10:18

6/07/13 

23:16 0.5 FLUMES 6/19/2013 6/08/13 08:25

6/08/13 

06:38 5/6 6/18/2013 

20:29 10.9

3105 E0B44FF 6/07/13 

10:18

6/08/13 

01:07 0.6 FLUMES 6/15/2013 6/12/13 05:08

6/08/13 

19:27 1/3 6/14/2013 

18:16 6.7

3080 E0B5A7A 6/07/13 

10:18

6/08/13 

01:21 0.6 TAILRACE 6/8/2013 0/0 6/08/2013 01:22 0.0

3083 E0B102B 6/07/13 

10:18

6/09/13 

18:00 2.3 TAILRACE 7/4/2013 0/0 7/04/2013 

01:16 24.3
23

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of 

first 

detection 

at weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

3085 E0B4F98 6/07/13 

10:18 TAILRACE 6/8/2013 0/0

3093 E0B1036 6/07/13 

10:18

6/08/13 

01:56 0.7 TAILRACE 6/8/2013 6/08/13 10:34 1/0 6/08/2013 13:44 0.5

3100 E0AD0CC 6/07/13 

10:18

6/08/13 

00:52 0.6 TAILRACE 6/8/2013 0/0 6/08/2013 01:59 0.0

3079 E0B31A7 6/12/13 

08:24

6/12/13 

22:59 0.6 CFFF 6/17/2013 0/0 6/15/2013 12:09 2.5

3081 E0AEE74 6/12/13 

08:24

6/15/13 

00:07 2.7 CFFF 6/16/2013 0/0 6/15/2013 10:56 0.5

3087 E0A64D8 6/12/13 

08:24

6/12/13 

15:02 0.3 CFFF 6/14/2013 0/0 6/13/2013 13:18 0.9

3094 DF7D5CA 6/12/13 

08:24

6/13/13 

09:41 1.1 CFFF 6/15/2013 0/0 6/14/2013 08:50 1.0

3084 E0ADAF1 6/12/13 

08:24

6/13/13 

18:40 1.4 FLUMES 6/20/2013 6/17/13 

06:48

6/17/13 

07:12 4/3 6/19/2013 09:40 5.6

3092 E0B924B 6/12/13 

08:24

6/14/13 

06:58 1.9 FLUMES 6/18/2013 0/0 6/17/2013 14:34 3.3

3097 E0AB510 6/12/13 

08:24

6/12/13 

19:05 0.4 FLUMES 6/17/2013 6/16/13 08:29

6/12/13 

19:13 1/2 6/16/2013 

08:38 3.6

3101 E0B3970 6/12/13 

08:24

6/19/13 

04:19 6.8 FLUMES 7/3/2013 6/19/13 

12:26

6/26/13 

04:00 9/5 7/02/2013 07:34 13.1

3102 DF7BDC3 6/12/13 

08:24

6/12/13 

23:38 0.6 FLUMES 6/23/2013 6/13/13 

10:41

6/13/13 

10:37 7/6 6/22/2013 

12:47 9.5

3089 E0A6A1B 6/12/13 

08:24

6/14/13 

13:36 2.2 DID NOT PASS n/a 6/16/13 16:48 1/0 6/17/2013 04:46 2.6

3091 DF7D7ED 6/12/13 

08:24

6/13/13 

14:37 1.3 DID NOT PASS n/a 6/18/13 01:37

6/14/13 

03:46 2/6 6/26/2013 

17:21 13.1

3096 E0B0786 6/12/13 

08:24

6/13/13 

18:22 1.4 DID NOT PASS n/a 6/14/13 10:52 1/1 6/20/2013 04:48 6.4
24

Radio 

tag ID PIT tag ID

Date and 

time of 

release

Date and 

time of 

first 

detection 

in forebay

Elapsed 

time from 

release 

(d) Fate

Date fate 

occurred

Date and

time of 

first 

detection 

at weir box

Date and

time of first 

detection at 

flume 

entrances

Number of 

times detected 

at weir 

box/flume 

entrances

Date and 

time of 

last 

detection 

in forebay

Elapsed 

time in 

forebay 

(d)

3077 E0ADE9D 6/12/13 

08:24

6/14/13 

02:38 1.8 WEIR BOX 7/1/2013 6/22/13 

12:54

5/27/13 

18:37 5/3 7/01/2013 04:12 17.1

3082 E0AF229 6/12/13 

08:24

6/15/13 

06:27 2.9 WEIR BOX 7/1/2013 6/16/13 

16:07

5/26/13 

14:48 8/10 6/30/2013 10:48 15.2
For additional information contact:

Director, Western Fisheries Research Center

U.S. Geological Survey

6505 NE 65th Street

Seattle, Washington 98115

http://wfrc.usgs.gov/

Publishing support provided by the U.S. Geological Survey

Publishing Network, Tacoma Publishing Service Center
Tobias and others— Evaluation of Juvenile Salmonid Behavior at Cowlitz Falls Dam, Washington, 2013—Open-File Report 2014–1042

ISSN 2331-1258 (online)

http://dx.doi.org/10.3133/ofr20141042