A STUDY OF FlSH JMPlNGEMENT 

AND SCREEN PASSAGE 

AT HANFORD GENERATING PROJECTA PROGRESS REPORT 

R. H. Gray 

T. L. Page 

E. G. Wolf 

M. j. Schneider 

January 1975 

BATTELL E 

PACIFIC NORTHWEST LABORATORY 

RICH LAND, WASHI NGTON 99352 
EXECUTIVE SUMMARY 

A study of screen impingement and passage of fish with 1/4 and 1/8-in. 

traveling screen openings is being conducted by Battelle-Northwest Laboratories at the Hanford Generating Project (HGP). The data from March 197.3 

through June 1974 are reported here. The objectives of this phase of the 

study were: 

To determine the species and estimate the total number of fish (particularly salmonid outmigrants) impinged and 'passed by the HGP intake 

screening system. . 

lo compare the effects of screen mesh size (l/&versus 1/4-in. openings) 

on the impingement and passage of fish. 

lo estimate the percentage of the salmonid outm'grant population 

impinged and passed by the HGP intake screens. 

Preliminary conclusions of this phase of the study are: 

0 

8 

8 

The intake of cooling water does not pose a threat to resident nonsalmonid species. 

The greatest impact is to 0-age chinook salmon recently emerged from 

redds during April and May between HGP and Priest Rapids Dam. 

Estimated impingement losses are 12 times greater with 1/8 than with 

1/4-in. screen openings but represent less than 1% of fry emerging 

from redds between HGP and Priest Rapids Dam. 

Estimated passage losses are similar with both size screen openings 

and may represent a maximum of 9% of the fry emerging from redds 

between HGP and Priest Rapids Dam. 

The impact of screen impingement is less than screen passage. 

The combined impacts of screen impingement and passage are virtually 

the same with both size screen openings, and may represent a maximum of 

9% of the fry emerging from redds between HGP and Priest Rapids Dam 

and about 3% of total estimated number of chinook outmigrants passing 

HGP. 

Fish too big to pass through the screen openings are able to enter 

the intake. 

Three alternative routes around the screens have been identified but 

gaps between the screen frames seen to be the most likely alternative 

route. Ongoing studies are addressing these problems. 

iii 

0 
ACKNOWLEDGEMENTS 

The authors wish to express their appreciation to the technical staff 

involved in the data collection: Mr. D. D. Dauble, Mr. D. A. Neitzel, 

Mr. E. W. Lusty, Mr. K. 0. Schwarzmiller, Mr. R. W. Hanf, Jr., and 

Ms. N. M. Rosentretet- and to those who graciously agreed to review the 

manuscript: Dr. R. F. Foster, Dr. B. E. Vaughan, Mr. J. B. Vetrano, 

Mr. W. 1. Templeton, Dr. C. D. Becker, Mr. D. G. Watson, Dr. 1. 1. Eberhardt 

and Dr. J. M. Thomas. 

We also wish to thank the HGP operations and maintenance personnel, 

particularly Mr. R. B. Pettus and Mr. A. MacDonald, whose assistance was 

i nval uabl e in conducting thi s research. 
C 

CONTENTS 

LIST OF FIGURES .................. 

LIST OF TABLES .................. 

INTRODUCTION ................... THE INTAKE STRUCTURE ................ 

MATERIALS AND METHODS ................ 

Beach Seining Observations and Dip Netting ........ 

Traveling Screen Wash Samples ............ 

Intake Samples .................. 

Experimental Re1 eases ............... 

RESULTS AND DISCUSSION .PRELIMINARY FINDINGS ........ 

Timing and Abundance of Fish Near HGP ........... 

Impact .................... 

Total Impact .................. 

SUMMARY OF PRELIMINARY CONCLUSIONS ........... 

REFERENCES.................... 

APPENDIX A .Common and Scientific Names of Salmonids 

ana Non-Sal monids ............. 

. vi 

.vi i 

.1 

.4 

.10 

.10 

.11 

*13 

.14 

.16 

.16 

.19 

.43 

.45 

.47 

.A. 1 

V 
LIST OF FIGURES 

1 Schematic of HGP Intake Showing Berms Before and After 

Removal . . . . . . . . . . . . . . . . . . . 2 

Aerial View of HGP Intake (right) and Outfall (left) . . . . 5 

Schematic of HGP Water Intake,Structure . . . . . . . . 6 

Plan View of HGP Water Intake Structure . . . . '. . . . 7 

Top of Vertical Traveling Screen Showing Hinged 

ScreenPan els. . . . . . . . . . . . - . . . . 8 

Beach Seine and Rainbow Trout Release Locations. . . . . . 11 

Screen Wash Collecting Trap . . . . . . . . . . . . 12 

The Number of Salmonids Impinged/Screen/hr and 

Collected by Beach Seine Haul in 1973 . . . . . . . . . 22 

9 The Number of Salmonids Impinged/Screen/hr and Collected 

by Beach Seine Haul in 1974 . . . . . . . . . . . . 26 

10 Sizes of 0-Age Chinook Impinged and Collected by 

Beach Seine in 1973 . . . . . . . . . . . . . . . 28 

11 Sizes of 0-Age Chinook Impinged and Collected by 

Beach Seine in 1974 . . . . . . . . . . . . . . ~ 28 

12 Percent of Released Fish in the Intake After Different 

Pumping Periods . . . . . '. . . . . . . . . . 36 

13 Estimates of 0-Age Chinook Screen Passage for 1974. . . . . 39 

14 Schematic Through One Intake Wall Traveling Screen 

and "Z-Frame" . . . . . . . . . . . . . . . . . 41 

15 Gaps Between Screen Frames. . .. . . . . . . . . . .42 
1 L 

LIST OF TABLES 

1 Salmonids and Non-Salmonids Collected by Weekly Beach Seining 

at Four Locations from 11 April 1973 Through 19 June 1974. . 17 

2 Numbers and Sizes of Salmonids and Non-Salmonids Collected 

by Weekly Beach Seining at Four Stations During the 1973 

and 1974 Downstream Migration ........... 18 

3 Number and Percent Composition of Fish Species Collected 

on 1/4-in. Traveling Screens from 28 March 1973 Through 

13 February 1974 ................ 20 

4 Number and Percent Composition of Fish Species Collected 

on l/4-and 1/8-in. Traveling Screens from 14 February 

Through 5 June 1974 .............. 21 

5 Numbers and Sizes of Salmonids and Non-Salmonids Impinged 

,on 7/4-in. Traveling Screens from 28 March 1973 Through 

13 February 1974 ............... 23 

6 Numbers and Sizes of Salmonids Impinged on 1/4- and 1/8-in. 

Traveling Screens from 14 February Through 5 June 1974. .. 24 

7 Number and Sizes of Non-Salmonids Impinged on 1/4- and 

1/8-in. Traveling Screens from 14 February Through

5 June 1974. ................ 25 

8 Numbers of Salmonids Impinged on 1/4- and 1/8-in. Traveling 

Screens Versus Time of Col lection (0945-1945 and 1945-0945)

from 14 February Through 5 J.une 1974 ........ 29 

9 Impingement and Passage of Previously Released Rainbow 

Trout on 1/4- and 1/8-in. Traveling Screens from 27 Through 

30 March 1974 ................ 31 

10 Salmonids and Non-Salmonids Sampled Inside the Intake 

Behind 1/4-!n. Traveling Screens from 29 March Through 

23 July 1973 ................ 33 

11 Salmonids and Non-Salmonids Sampled Behind 1/4- and 

1/8-in.Traveling Screens from 6 March Through 31 

May 1974. ................. 34 

12 Numbers of Rainbow Trout Released and Recaptured Inside 

Intake After Different Pumping Durations ....... 35 

vi i 
LIST OF TABLES (contd) 

13 Daily Numbers of Chinook Salmon Sampled on and Behind 1/4­

and 1/8-in. Traveling Screens by Fintrol and Dip Net During

Spring 1974 ................. 38 

14 Summary of Estimates Impacts Due to Impingement and Passage 

of 0-Age Chinook Salmon with 1/4- and 1/8-in. Screens During 1973 and 1974 ................ 39 

viii 
INTRODUCTION 
A STUDY OF FISH IMPINGEMENT AND SCREEN PASSAGE 

AT HANFORD GENERATING PROJECT -A PROGRESS REPORT 

R. H. Gray 

T. L. Page 

E. C. Wolf 

M. 1. Schneider 

INTRODUCTION 

In March 1973, Battelle-Pacific Northwest Laboratories (BNW) began an 

ecological baseline survey of the Columbia River in the vicinity of the 

Washington Pub1 ic Power Supply System's (WPPSS) Hanford Generating Project 

(HGP), and an assessment of interactions between plant operations and the 

biotic components of the river. This report presents progress to date of 

that part of the study which evaluates the impact of cooling water intake 

on the Columbia River fish community. 

A number of juvenile chinook salmon were observed behind the HGP 

traveling screens in the Spring of 1973. Sampling was initiated to determine the magnitude of fish impingement and screen passage. Sampling 

problems precluded enumeration of the actual number of fish passing the 

screens during the 1973 spring outmigration of juvenile salmon. Nontheless, 

the species of fish passed and the time of year that passage occurred were 

determined. A more comprehensive evaluation of passage and impingement 

was accomplished in 1974. 

One factor that appeared to increase the congestion of juvenile 

s'almonids in front of the intake was a forebay caused by berms hat exte ded 

some distance into the river both up and downstream (Figure 1). A gyre 

within this forebay apparently increased the potential for mult ple exposure of fry to impingement and screen passage. To mitigate the impact of 

the intake on outmigrating salmon, the Washington State .Department of 

1 
------ 

COLUMBIA RIVEi3 FLOW 

\ / 

I \ 

I \ 

BEFORE BERM REMOVAL 

AFTER BERM REMOVAL 

FIGURE 1. Schematic of HGP Intake Showing Berms Before and After Removal 

Fisheries requested that the intake forebay be modified by removing the 

berms before the 1973 spawning season. Berm removal was accomplished in 

September 1973 and apparently diminished the gyre in front on the pumphouse. 

Another factor that appeared to exacerbate fish passage through the 

traveling screens was the 1/4-in. size of the screen openings. The travefing screens were not specifically designed as fish barriers, but to protect 

the circulating water system from particulate material in the water. As 

originally designed, the screens were only partially. effective in excluding 

fish. Therefore, to reduce passage, the Washington State Department of 

Fisheries requested that the size of the screen openings be reduced to 

1/8-in. before the next salmonid outmigration. In February 1974, WPPSS 

began changing the traveling screen mesh from 1/4 to 1/8-in. openings. 

However, in response to a request by BNW and WPPSS, the State Department of 

Fisheries agreed to leave one-half of the traveling screens unchanged. 

This action afforded the opportunity for direct comparison of impingement 

and passage of fish with the two different traveling screen openings. A 

research program was designed with the following objectives: 
I . 

0 To determine the species and estimate the total number of fish (particularly salmonid outmigrants) impinged and passed by the HGP intake 

screening system. 

To compare the effects of screen mesh size (l/&versus 1/4-in. openings) on the impingement and passage of fish. 

To estimate the percentage of the salmonid outmigrant population 

impinged and passed by the HGP intake screens. 

3 
’. 4 

THE INTAKE STRUCTURE 
THE INTAKE STRUCTURE 

Washington Public Powzr Supply System's HGP is located at Columbia 

River Mile 380 next to the Atomic Energy Commission's N Reactor. The pumphouse is a typical bankside, shoreline installation (Figure 2). The site 

for the intake structure was excavated to about 70 ft below the normal 

river bottom and extends into the river for 75 to 125 ft. At design low 

flow (36,000 cfs), the water in front of the intake is about 20 ft deep. 

Itater entering the coolinq system from the river first passes through 

coarse trash racks, which consist of 5- by 1/2-in. vertical steel grates 

which are 3 7/4 in. apart (Figure 3). A curtain wall behind the trash 

racks extend to within 22 ft of the bottom and is 3 to 5 ft below the 

water surface for most of the year. Vertical traveling screens are located 

abwt 8 ft behind the curtain wall. There are 6 screen bays (Figure 4),

each with a row of vertical screens. Each vertical row consists of a 

series r,f panels, 10 ft by 2 ft, hinged into a continuous chain (Figure 5). 

The panels are made of staipless steel mesh, originally with 1/4-in. openings. Trash collected on the screens is lifted vertically to the top of 

L~Gstructure by screen rotation where a high pressure spray (80 psi) 

cashes impinged material into a trough (Figure 3) and returns it via a 

sl:;ice-i.iay and pipe to the river downstream of the plant (Figure 2}. 

Internally, the intake pirmphouse is divided into two replicate halves, 

eti::? with two 141,000 gpm ?amps drawing water through three vertical rows 

vf trzveling screens (Figgre 4). The total pumping, capacity of both halves 

1s CjF,4,00@ gpni. The desi23 approach velocity (measured values are not 

?:z;lable) in front of the screefis is less than 1 fps. However, the actual 

~ ~ ~ ~ :velocity i 1 ~ ~is inot ~ \ the ~ approach velocity, but rather the velocity . . 

. tii:-(:!dgh the screefi mesh itself. The calculated velocity through the 

L'reens is 1.95 fp; at minimus water level for the 1/4-in. opening screens (1 1 

:.it(.: x.35 fils through the sr.aller 1-8 in. screens. Since throughol;t 

c;. ,:>I. all of the study period the river exceeded minimum low flow, the 

i!.,:iir:ging velo-,itics IO wtiich the fish were exposed were less than these 

. > 

: ! :cL,i2ted vtil~c3. 

4 
U 

t 

tw 

>o 

n 7

a3 

I -F 0

L 

Q: L 

Q 

w 

W 

CY 

3 

a 

W 

LL 
/I

I 

FIGURE 3. Schematic of HGP Water Intake Structure 

6 
C 

I +-cow* , fCpuyps 

TRASH RA 

I TO COUDENSLRS 

I 

1?UNCI 

FIGURE 4. Plan View of HGP Water Intake Structure 

7 
8 
During the spring of 1974, one-half of the 6 vertical rows of traveling screens were changed to 1/8-in. openings. By rotating the screens 

either 1/4- or 1/8-in. openings could be placed in the water. On the 

upstream (No. 2) side of the intake, 1/8-in. openings were in the water at 

all times. For comparison, on the downstream (No. 1) side, screens with 

1/4-in. openings remained in the water throughout most of' the 1974 salmon 

outin i g ra t i on . 

9 
a 1 

MATERIALS AND METHODS 
-- 

MATERIALS AND METHODS 

The segment of the impingement and passage sampling program discussed 

below was initiated in late March 1973 and continued through mid-June 1974. 

Beach1 seine samples and visual observations and dip netting of the intake 

forebay were included in the investigative program to determine the timing 

and abundance of salmon outmigrants emerging from spawning redds upriver 

from the intake and the movement of resident fish species. Samples of the 

traveling screen washings and from inside the intake were obtained to estimate the magnitude of impingement on the screens and passage through the 

screens. All of the above samples were collected on a routine basis except 

when' the screen wash sampling schedule was interrupted by the annual summer 

maintenance outage during June and July 1973. Controlled experimental 

releases of rainbow trout (Salmo gairdneri)(a) were made in the river 

during March 1974 to simulate downstream migration. Samples to detect 

these fish were taken from the screen wash and inside the intake behind 

screens of both sizes. Releases were also made inside the intake as a 

check on sampling effic ency and to estimate residence time once f sh were 

insidi. the intake. 

All fish collected were identified to species where possible, 

measured and preserved in 10% formalin. A few impinged fish were too 

badly mutilated or decomposed to be identified. A number of sucker fry 

(Catostomus spp. ) collected by beach seine (July-September 1973) could only 

be identified to genus. 

Beach Seining Observations and Dip Netting 

Weekly beach seining was carried out from 11 April 1973 through 

19 June 1974 at four locations in the river with a 30-ft net of 1/8-in. 

mesh. Two stations were located on each side of the river, so that two 

(a) Scientific and common names of all fish mentioned in this report are 

listed in Appendix A. 

. 

10 
-- 

were above and two were below the intake (Figure 6). Dai y observat ons 

and dip netting of the intake and forebay water were made during the 

salmon outmigrat ion. 

UT RELEASE POINT 

3.. i IcCC . <­ --. 1_---- t 

FIGURE 6. Beach Seine and Rainbow Trout Release Locations 

Traveling Screen Wash Samples 

Traveling screen wash samples were obtained on odd number calendar 

working days throughout most of the study period from 28 March 1973 

through 19 April 1974. Samples were collected daily during the work week 

from 21 April to 5 June 1974. 

The traveling screens at HGP are usually washed for approximately 

20 min daily during most of the year. However, during the spring freshet 

when large amounts of particulate matter are suspended in the water, the 

screens are washed twice daily. This latter schedule usually begins in 

mid-April and continues until late May when the plant ceases operation for 

summer maintenance. The 20 min morning wash routinely occurs between 0830 

and 1100 hr. During the spring freshet, the additional 20 min evening 

wash occurs between 1800 and 2130 hr. During this study, the morning wash 

was conducted at 0945 hr. The time of the evening wash was more variable, 

but usually took place about 1945 hr. 

In order to collect screen washings, a trap (Figure 7) was inserted 

into the trash return sluice-way. From 28 March 1973 to-14 February 1974, 

11 
e 1 
L 

t 

when the traveling screens all had 1/4-in. openings, the trap was lined 

with 1/4-in. mesh screen. From 14 February 1974 until the termination of 

the study, when the intake had both 1/4- and 1/8-in. traveling screens, 

the trap was lined with 1/8-in. mesh screen. When two screen sizes were 

in use, each was washed separately on each sample date. From 1 April 

through 15 April 1974, at the request of the Washington State Department 

of F-isheries, all intake screens had the smaller 1/8-in. openings in the 

water. During this period an evaluation by the Department of Fisheries 

of the program resulted in their allowing the comparison of 1/4- and 1/8-in. 

screen impingement and passage to continue. Therefore, at all other times 

during the 1974 outmigration both 1/4- (No. 1 side) and 1/8.-in. (No. 2 side) 

openings were in the water and comparative samples were collected. Once a 

sample was collected, the trash was hand-sorted, fish were identified, and 

their condition noted. Fish from morning screen wash samples that exhibited 

either body or opercular movements were placed in an aquarium supplied with 

running river water. At the end of. 24 hr the number of dead and living 

fish, determined by opercular movement, was recorded. 

intake Samples 

Several sampling schemes were considered or tried for collecting fish 

passing the traveling screens during normal plant operation. Most of these 

schemes were unsuccessful due to the internal configuration of the intake, 

the large volumes of water pumped, and the need to provide complete safety 

for research personnel and not endanger steam plant operations. The successful sampling schemes are discussed below. 

To assess the number, species and size of fish that passed through the 

traveling screens during the initial phase of the passage program (29 March 

1973 .through 13 February 1974), dip netting was conducted inside the No. 1 

side of the intake (only 1/4-in. screens were installed in the plant at 

this time). On 23 July 1973, during the beginning of the annual summer 

maintenance outage, Fintrol 5, a commercial fish toxicant was used to 

assist in collecting and quantifying the number of fish passing the 

13 
traveling screens. The water inside the intake was treated with 1 gal 

(8 lb 4 02) of Fintrol 5 before dip netting. The active ingredient of 

Fintrol 5, antimycin A, is absorbed into the gills of fish, interferes 

with respiration and eventually results in death. Fish exposed to 

Fintrol 5 swim slowly to the surface and are easily collected, Dip netting 

after poisoning continued for an average of 2.5 hr. 

For the remainder of the period when there were two screen sizes 

(14 February 1974 throuqh 5 June 1974), dip netting was continued and 

quantification of effort attempted inside both sides of the intake. To 

provide a comparison of the daily variation in numbers of fish entering the 

intake structure through both size screens, records of the length of time 

spent dipping (1 through 8 May) and the number of dips (9 through 24 May) 

were kept. Samples from both sides.of the intake were also collected using 

Fintrol 5 on several occasions from late March through late Play during the 

1974 salmon outmigration. The pumps must be off in order to sample effectively with Fintrol 5 since pumping will result in rapid dilution of the 

chemical, thus making it ineffective. Therefore, samples were collected 

during either scheduled or unscheduled plant outages. 

Experimental Releases 

Experimental releases of rainbow trout (Salmo gairdneri) were made in 

late March 1974. Rainbow trout were used because of their immediate av~itr;la.­

bility. Prior notice of the outage timing was insufficient to procure 

other salmonid species. Since the released fish were the only rainbow fry 

in the vicinity of HGP at this time, they constituted an easily identifiable 

experimental population. Two sub-groups of rainbow fry were established by 

cold branding on the right or left side above the lateral line. After 

branding, fish were held in the laboratory for a minimum of three days to 

insure recovery before they were transported to the site. Thus, three 

experimental populations were established for these studies: unmarked 

fish, branded leftside, branded rightside. 

14 
To estimate the portion of a given population of fish passing a 

specific point in the river that might be impinged or passed by the HGP 

intake with either 1/8- or 1/4-in. screen openings, 20,000 unmarked rainbow fry were released near shore 500 to 600 yd upstream of the intake 

(Figure 6). This distance was considered to be sufficient for the released 

fish to orient to river currents before reaching the intake. Visual observation of released fish showed that they immediately oriented to the 

current and confirmed this assumption. Following the experimental release, 

the screen wash and intake bays were sampled daily. 

To estimate the number of fish that might be impinged or passed once 

behind the curtain wall, cold branded (left side) fish were planted in the 

six bays immediately in front of the traveling screens. Releases behind 

the curtain wall totaled 2400 juvenile rainbow in front of the 1/4-in. 

screens (No. 1 side) and 2098 in front of the 1/8-in. screens (No. 2 side) 

The screen wash was then sampled twice daily to estimate impingement of 

branded fish. The water inside the intake was poisoned one day later to 

define passage of branded fish through the screens. Differences between 

passage and impingement by the two d fferent size screens were then 

compared. 

Releases of cold branded (right side) rainbow trout were made behind 

the traveling screens (in both the No. 1 and No. 2 sides) to estimate the 

residence time of fish, inside the intake after a known pumping duration. 

Any subsequent appearance of these fish in the screen wash would indicate 

that they passed from behind the screens to the river side and then became 

impinged. At the time of these releases, the No. 1 side had 1/4-in. screens 

in the water while the No. 2 side was fitted with 1/8-in. screens. Three 

seDarate releases were made behind the screens. They consisted of 1500, 

1158 and 1150 juvenile rainbow trout. The fish were sampled by Fintrol and 

dipnet after pumping periods of different lengths. Additionally, another 

1000 juvenile rainbow were released inside the intake and sampled imnediately (i.e., no pumping) to test the efficiency of the Fintrol sample 

method. 

15 
* 

7 

RESULTS AND DISCUSSION - PRELIMINARY FINDINGS 
, 

RESULTS AND DISCUSSION - PRELIMENARY FINDINGS 

Timing and Abundance of Fish Near HGP 

Chinook salmon (Oncorhynchus tshawytscha) made up 99.5% of the salmonid . 

catch and 32.2% of the total catc'h from all stations in weekly beach seine 

hauls between 11 April 1973 and 19 June 1974 (Table 1). In 1973, juvenile 

salmon (mean fork lengths, range 4.0-5.4 cm) appeared in greatest numbers 

in April and May (Table 2). In 1974, juvenile salmon (mean fork lengths, 

range 4.2-5.4 cm) were most abundant from May through the first part of June 

(Table 2). That is, the major portion of the salmon outmigration occurred 

later in 1974 than it did in 1973. The most common non-salmonid species 

collected were the redside shiner (Richardsonius balteatus), northern 

squawfish (Ptychocheilus oregonensis) and sucker fry (Catostomus spp. ) -

Other species of fish were collected less frequently (Table 1). Nonsalmonids were collected in greatest numbers from mid to late May in both 

years (Table 2). 

Peak migration of 0-age chinook salmon past Priest Rapids Dam occurs 

in August. (3) Chinook from hatcheries and spawning channels (fork length 

8-10 cm) are released from mid-May to July. Naturally spawned Hanford 

chinook, however, still maintain the .historical migration pattern. Outmigration generally begins in mid-March and peaks from April through June with 

fish averaging 4.1-4.9 cm (fork length). Sythe end of July most Hanford 

spawned chinook have apparently departed the area. (4) The timing of the 

1973 and 1974 chinook outmigration,and the sizes of the fish reported here 

also agree with the historical migration pattern, indicating that fish collected by beach seine are offspring of adults spawning in the fall in the 

Hanford area. Fish produced from redds, hatcheries and spawning channels 

upriver from Priest Rapids Dam appear later in the year when the plant is 

usual'ly shut down for maintenance. These fish are also larger when they 

pass through the Hanford area and, therefore, less likely to be affected by 

HGP pumping operations. 

16 
-- 

-- -- 

TABLE 1. Salmonids and Non-Salmonids Collected by Weekly 

Beach Seining at Four locations from 11 April

1973 Through 19 June 1974 

Total No. % Total 

SALMON IDS 

Oncorhynchus ts hawyt scha ( Wa l'baum) 'I 359 32.2 

Prosopium will iamsoni (Girard) 3 0.1 

-0. nerka (Walbaum) 2 

-0. kisutch (Walbaum) 1 

Salmo gairdneri Richardson 1 

Total Salmonids 1366 32.3 

i\lON- SALMOti ID S 

Richardsonius bal teatus I(Richardson) 1257 29.8 

Ptychochei 1 us oregonens i s (Richardson) 71 0 16.8 

I_Ca tos tomus fry 632 15. c 

Mylocheilus caurinus (Richardson) 173 4.1 

Catostornus 

- macrocheilus Girard 55 1.4 -___­

-_ Gasterosteus - aculeatus Linnaeus 4 0.1 

Cottus 3sper Richardson 4 0.1 

Cottus rhotneus ___- (Srni th) 4 0.1 

Acrocheilus 

____-_.

alutaceus - Aqaqc;iz & Pickering 4 3.1

Cottus perpl exus Gi 1bert & tverrnann 1 

Lepomis - -__­ gibbosus (Linnaeus) 1

Rhinict& _____ dataractae -. (Valenciennes) * l

-R. falcatus - Eigenmann 8 Eigenmann 1 

Cyprinus carpio Linnaeus 1 

To tal Non- Sal nionids 2851 67.5 

Total Fish 421 7 

17 
L 

TABLE -2. Numbers and Sizes of Salmonids and Non-Salmonids Collected by

Weekly Beach Seining at Four Stations During the 1973 and 1974 

Downstream Migration 

Sa 1monids Non-Sa 1moni ds 

Fork Lengk Fork Length1973 

No. 

Hauls 

Total 

No. 

No/ 

__Haul 

ALg. Range 

-(cm) (cm)

Total 

No. 

NO/ 

-

Haul 

Avg. Range 

__ (cm) (4

April 6 129 21.5 4.7 3.5-16.0 2 0.3 3.6 2.2-5.0 

1-21 

22-30 8 69 8.6 , 5.4 3.4-14.5 1 0.1. 2.5 

May

1-7 

0 

8-1!5 8 44 5.5 4.0 3.5-4.8 1 0.1 1.8 

16-25 4 80 20.0 5.0 3.6-21.4 188 . 47.0 5.5 2.7-49.3 

26-31 4 115 28.8 5.2 3.6-7.6 117 29.3 6.8 4.0-9.6 

June 4 23 5.8 6.2 4.0-12.5 3 0.8 18.7 8.1-37.5 

1-8 

9-13 4 13 3.3 7.9 4.1-15.7 0 - - - 1974 

March 8 8 1.0 5.5 3.5-16.1 2 0.3 4.0 3.0-4.9 

1-15 

16-21 4 9 2.3 11.5 3.8-31.5 5 1.3 3.9 2.7-5.4 

22-31 4 9 2.3 8.3 3.7-29.5 10 2.5 5.4 3.1-12.7 

Rpri 1 4 4 1.0 4.2 3.7-5.1 4 1.0 5.1 3.3-7.2 

1-7 

8-1 5 8 45 5.6 4.4 3.7-10.3 3 0.4 4.4 3.7-5.2 

22-30 4 9 2.3 4.0 3.9-4.3 7 1.8 5.0 4.6-7.2 

hY 4 46 11.5 4.2 3.8-4.6 2 0.5 5.2 4.0-6.3 

1-7 

8-1 5 8 244 30.5 4.2 3.6-5.2 15 1.9 5.7 3.0-14.0 

16-22 4 io5 26.3 4.4 3.7-5.4 352 88.0 4.6 2.5-10.3 

23-31 4 62 15.5 4.6 3.8-5.5 1 ' 0.3 4.7 -

June 4 142 35.5 4.8 3.5-6.6 6 1.5 5.3 4.7-6.8 

1-8 

9-1 5 4 139 34.8 5.4 3.8-7.3 2 0.5 25.0 4.1-45.8 

16-22 4 51 12.8 5.4 3.8-7.8 19 4.8 8.2 5.8-13.2 

- - - - - - - ­

18 
These observations indicate that the salmonids most susceptible to 

screen impingement and passage at HGP are juvenile fall chinook spawned 

between the intake and Priest Rapids Dam. This conclusion is supported by 

the appearance of juvenile chinook salmon on and behind the traveling screens 

from mid-March through May (see IMPACT). The time of appearance and size of 

these fish indicate that they belong almost exclusively to the O-age class 

and that they originate between Hanford and Priest Rapids Dam. 

Daily observations and dip netting of the intake forebay water throughout the study period indicated that salmonid fry and smolts were more abundant during 1973 than in 1974. The fewer salmonids observed in the forebay 

during 1974 may have resulted from berm removal, but our ability to see the 

fish was influenced in 1974 by factors such as increased river runoff and 

water turbidity. 

Impact 

Impingement on the Traveling Screens 

Four salmonids and 11 non-salmonid species totaling 243 fish were collected on the 1/4 in. traveling screens from 28 March 1973 through 13 February 1974 (Table 3). Chinook salmon (Oncorhynchus tshawytscha) accounted for 

57.6d of the fish impinged and 96.6% of the salmonids impinged. The threespined stickleback (Gasterosteus aculeatus), redside shiner (Richardsoni!Js 

bal teatus) and peamouth chub (Mylocheilus caurinus) were the most common 

non-salmonids impinged. Other species were impinged less frequently. 

From 13 February through 5 June 1974 chinook salmon were the only 

salmonids impinged on either size traveling screens (Table 4). This species 

iiiade up 78.3% of 276 identifiable fish impinged on 1/4-in. screens and 

90.9’:of 2637 identifiable fish impinged on 1/8-in. screens. Ten species of 

non-salmonid fish were impinged on both 1/4- and 1/8 in. screens. Three 

additional non-salmonid species (total 13) were impinged on 1/8-in. screens. 

In 1974, the three-spined stickleback again was the predominant non-salmonid 

impinged on either 1/4 or 1/8-in. traveling screens. The reside shiner 
--- - 

- --- 

- - --- 

TABLE 3. Number and Percent Composition of Fish Species Collected 

on 1/4 in. Traveling Screens from 28 March 1973 Through 

13 February 1974 

SALMON IDS 

Oncorhynchus -__­ tshawytscha (Wal baum) 

Prosopium williamsoni -(Girard) 

0. kisutch (Walbaum) -. A­

-0.. nerka (Wal baum) 

Total Salmonids 

NON- SALMON IDS 

Gasterosteus ___ aculeatus Linnaeus __--

Total % of Total 

No. Fish Coll ected 

140 57.6 

3 1.2 

1 .4 

1 .4 

145 59.8 

Richardsonius balteatus -__ -. -- _______ (Richardson) 

Mylocheilus caurinus -__ -(Richardson) 

Cottus asper Richardson ~ 

Catostomus macrocheilus Girard - ..- ---

Entosphenus tridentatus (Gairdner) -- _- ___- -_ -_-

Alosa sapidi ssima (Wi 1 son) - -__- -. 

31 12.8 

19 7.8 

19 7.8 

8 3.3 

7 2.9 

4 1 .G 

4 1.6 

~ ---___ -. __-

Cottus beldingi Eigenmann 8 Eiqenman 1 .4 

. --~

Ptychocheilus oreEensis (gichardson) 3 1.2 

Cyprinus c.arpio Linnaeus ' .4 

Perca fl avescens (Pli tchi 11 ) -4 - -

Total Non-Sa lmonids 98 40.3 

Total Fish 243 

20 
TABLE 4. Number and Percent Composition of Fish Species Collected 

on llband 7/8-in. Traveling Screens from 14 February 

Through 5 June 1974 

-1/4-in. Screens 1/8-in. Screens 

X of Total % of Total 

Total Identifiable .Total Identifiable 

No. Fish Collected No. Fish Collected _-

SALMON1DS 

Oncorhynchus tshawytscha (Walbaum) 216 78.3 2398 90.9 

NON-SALMONID S 

Gasterosteus aculeatus Linnaeus 21 7.6 85 3.2 

Richardsonius bal teatus (Richardson) 13 4.7 32 1.2 

Cottus asper Richardson 7 2.5 24 .9 

Ptychocheilus oregonensis (Richardson) 5 1.8 46 1.7 

-~ Cottus bairdi Girard 3 1.1 6 .2 

Catastomus macrocheilus Girard 3 1.1 14 .5 

Mylocheilus -caurinus Richardson 3 1.1 12 .5 

Entosphenus tridentatus (Gairdner) 2 .7 12 .5 

Cottus beldingi Eigenmann & Eigenmann 2 .7 ' 1 .4 

Percopsis transmontana (Eigenmann & 1 .4 4 .2 

Eigenmann) 

Cottus rhotheus (Smith) 1 

Cyrpinus Carpio Linnaeus 1 

Acipenser transmontanus Richardson - - -

1 - __ 

Total Non-Salmonids 60 21.8 239 9.0 

UNIDENTIFIABLE 22 7.4' 47 1 .a1 

Total Fish 298 2684 

% of total number of fish collected 
(Ri chardsonius bal teatus) , prickly sculpin (Cottus asper) and northern 

squawfish (Ptychochei 1us oregonensis) were the next three most common nonsalmonids impinged. Other non-salmonid species were again represented less 

frequently on both 1/4- and 1/8-in. screens. 

In 1973, the greatest impingement of both salmonids and non-salmonids 

on 1/4-in. traveling screens occurred between late April and mid-May 

(Figure 8, Table 5). The size of impinged fish ranged from 2.3-71.5 cm 

fork length. Approximately half of the fish larger than 10 cm and a few 

smaller fish were decomposing indicating that death had occurred prior to 

impingement. Fish as large as 38.2 cm (gravid female whitefish) and apparently in good condition were also impinged. Comparison of the average sustained swim speeds (i.e., > 3 fps) of these larger fish(5) to the calculated 

water velocity of 1.95 fps through 1/4-in. screens at minimum low water indicates that they were severely stressed (i-e., disease), or were dead before 

impingement. 

a500 

1973 

-BEACH SEINE 

-__--SCREE& WASH 114 INCH 

0 03c --LF-Li~--

JAlvUARY FEBRUARY WARCCI’ APRIL WY JUNE 

FIGURE 8. The Number of Salmonids Irnpinged/Screen/hr and 

Collected by Beach Seine Haul in 1973 

22 
TABLE 5. Numbers and Sizes of Salmonids and Non-Salmonids Impinged 

on 7/4-in. rave 7 ng Screens from 28 March 7973 Through 

. 13 February 1974 

Salmonids Non-Salmonids 

Sampl ing

Effort 

(hr) 

Fork Length

No -1 ‘la)

Total Screen/ Avg. Range

No. hr 

Total

No. 

fork Length

No./

screen/ (a) Avg . :,ax.: 

hr (cm) (irn) 

March 48 0 .0000 - - 1 .0035 5.5 -

Apri 1 220 6 ’ -0045 3.8 3.3-4.0 16 .0121 5.6 2.3-14 1 

1-21 

Apri 1 

22-30 

28 18 .lo71 4.6 3.2-9.5 9 .0536 4.7 3.2-6. 

May

1-7 

42 61 .2421 5.3 3.5-9.2 17 .0675 4.7 3.5-71 5 

May

8-15 

42 44 .1746 5.1 3.5-19.4 2 .0079 16.8 4.3-29. 3 

May

16-25 

56 2 .0060 4.9 4.6-5.1 2 .0060. 4.2 3.9-4.4 

June(b) 

July (b) 

August 168 1 .OOl 0 38.2 - 3 .0030 17.7 15.8-19.5 

September 

Oc t ober 

264 

72 

1 

0 

.0060 

.0000 

43.3 

- -

- 15 

15 

.0095 

.0035 

6.3 

5.3 

3.3-19.8 

4.5-8.9 

November 120 8 .OD1 1 51.9 38.9-71 -5 2 .0028 3.6 3.0-4.1 

December I20 1 .0014 29.3 - 2 -0028 5.4 5.1-5.5 

January 168 0 .oooo - - 6 .0060 8.6 3.6-14.7 

February

1-13 

96 2 .0035 6.3 3.9-8.7 9 .0156 6.3 4.2-10.0 

(8) Six vertical rows of traveling screens were washed on each sample date. 

(b) Plant shutdown for annual summer maintenance. 

Number and size of all fish impinged per screen per hour on 1/4- and 

7/8-in. screens from 14 February through 5 June 1974 are shown in Tables 6 

and 7. Dlrring this period, non-decomposed larger (up to 52.0 cm) fish were 

impinged on both size meshes. Again, based on capable sustained swim speeds 

and the calculated velocity through the screens (2.36 fps with 1/8-in. openings at minimum low water), it is unlikely that these fish were impinged 

without experiencing some debilitating preimpingement event. 

23 
I 

I 

0 

0 

0

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I 

- i 

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SI­ 0 cu 05 Lo 

*- aJ I i 

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13 

v 

h 

I Ln h I 

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v 

f j0 ! I . . . . . , S d.j-fmlnCn 

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25 
Y 

The sampling technique was not conducive to collecting impinged fish 

alive. Fish could be impinged for several hours before being washed into 

the collection basket. Live-dead counts for morning samples indicate that 

about 6% of all fish impinged on 1/4-in. screens in 1974 were alive at the 

time of collection. Approximately 1% of all fish impinged on 1/8-in. screens 

were collected alive during this period. Though these estimates of live 

impingement may be low, nonetheless comparison.of survival between the two 

screen sizes is reasonable. The data do indicate the percent of fish that 

might be expected to survive impingement on both size screens under the 

present screen wash regime. 

In 1974, peak chinook impingement on the 1/4-in. screens occurred from 

late April through early May (Tsable 6, Figure 9). However, peak chinook 

impingement on 1/8-in. screens shifted to mid-May was up to 200 times greater 

than impingement on 1/4-in. screens.’ Additionally, there was an early impingement peak in March and April on 1/8-in. traveling screens that did not occur 

on 1/4-in. screens. This clearly indicated that 1/8-in. screens resulted in 

greater impingement of chinook outmigrants over a longer period. 

1914 

-BEACH SCINE 

-----SCREEN WASH lld INCH 

--SCREEN WASH 1R INCH 

18 

16 

14 

12 

10 r 

rn 

a 

w 

g m5

z 

6 

4 4 

2 

0 

JANUARY FEBRUARY MARCH APRIL MAY JUNE 

FIGURE 9. The Number of Salmonids Impinged/Screen/hr and Collected 

by Beach Seine Haul in 1974 

26 
The timing and maximum abundance of 0-age chinook impinged on 1/4-in. 

screens in 1973 and on 7/4- and 1/8-in. screens in 1974 occurred before 

maximum catches collected by beach seine (Figures 8 and 9). This is probably 

a function of fish size. The fish collected by beach seine after impingement 

had declined to zero were older, larger, and more capable of avoiding intake 

approach velocities but not beach seine hauls. The average size (i.e.¶ fork 

length) of impinged 0-age chinook are compared with those of 0-age chinook 

collected by beach seine in Figures 10 and 11. As average size increased 

during early June in beach seine samples (Figures 10 and ll), salmon impingement fell to near zero on both 1/4- and 1/8-in. screens (Tables 5 and 6). 

The early impingement that occurred on 1/8-in. traveling screens in 

1974 and the greater numbers impinged was probably due to the smaller 

openings and the higher approach velocities. Average sizes of impinged 

salmon did not differ between 1/4- and 1/8-in. screens (Table 6), nor did 

average size of salmon impinged in 1973 differ from those impinged on the 

1/4-in. screens in 1974 (Tables 5 and 6). 

According to Mains and Smith,(6) 0-age chinook move through the Hanfot-d 

reach of the Columbia River mainly at night. More than 70% of their catch 

was made between 1800 and 0600 hr with peak numbers between 0300 and 0600 hr. 

Our results indicate that impingement may be greater during the day (0945­

1945 hr) than at night (1945-0945 hr) on traveling screens of both sizes 

(Table 8). This may be the result of congregation of 0-age chinook juveniles 

in shoreline feeding area (i.e., around the intake and intake forebay) ?c:?­

ing the day. 

Estimates of Total Impingement 

Estimates of total impingement during the 1973 and 1974 outmigration 

can be obtained from the number of fish impinged per screen per hour 

(Tables 5 and 6). Multiplication of these values by the number of screens 

(6) and the number of hours in a day (24) gives the number of fish impiEg?d 

daily. Each of the values is then multiplied by the number of days in each 

of the period reported. Finally, the number of fish in each period (Tables 5 

and 6) is summed over the entire impingement season to obtain an estimate of 

the total number of fish impinged. 

27 
------ 

--- 

-- 

------ 

It)> 

60 

f 55 -

E 

35 

30 

65 

60 

E 

� 55 

c 

1 

0 510 

z 

I.. 

-1 

2 45 

Cc 

0 

40 

- 1973 

BEACH SEINE -

SCREEN WASH 114 INCH 

-

I I I I I 

JANUARY FEBRUARY MARCH APRIL MAY ' JUNE 

FIGURE 10. Sizes of 0-Age Chinook Impinged and Collected 

by Beach Seine in 1973 . 

1974 -

BEACH SEINE 

- SCREEN WASH 114 INCH 

SCREEN WASH 1/8 INCH 

-

35 I" 

30 L L l I I 

JANUARY FEBRUARY MARCH APRIL MAY JUNE 

FIGURE 11. Sizes of 0-Age Chinook Impinged and Collected 

by Beach Seine in 1974 

28 
h 

0 

00-

oom 

In 

al d 

m h m -0 0 h

000 Ln h VI 

m In 

0 I -0 0 m coo 0 Ln ?Y'l 0 In 9 m Nh 0 .. '4 .- mm 

In 

- b m h I Wrn 0 e 0 hm 7 m " 

h cn m m om 0 W 43 m a h om 0 u co m - 0 em 0 

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0 0 mcu z 0

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00- I I In d

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7 

>. Ln L fi I a I c 3 7 0 7

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L cu m a I I E aJ W N a 3 LL - cu IT 3 

29 
1973 Season: By this method about 600 0-age chinook salmon are estimated to have been impinged on 1/4-in. traveling screens during the 1973 

outmigration. The total number of chinook outmigrants from upriver passing 

the HGP intake in 1973 is estimated by the Washington State Department of 

Fisheries to have been 2.1 million.(7) Most (1.86 million) of these came 

from natural spawning or spawnin? channels above or at Priest Rapids Dam. 

The remainder (0.24 million) represent emergent fry from fall chinook 

spawned between Priest Rapids Dam and the intake. This estimate, however, 

based on 1972 aerial redd counts may be low because of adverse weather 

conditions contributing to poor visibility during the aerial surveys. (8) 

The estimated 600 fish impinged on 1/4 in. traveling screens, in 1973, 

represent 0.3% of the estimated outmigration emerging between HGP and 

Priest Rapids Dam. 

1974 Season: The values in Table 6 (i.e., number of salmonids impinged/ 

screedhour) can be used to estimate the number of chinook salmon impinged 

during the 1974 outmigration if the entire intake had screens of only one 

size. Impingement losses were estimated to be at least 1200 fish with 

1/4 and 14,278 fish with 1/8-in. screens. Total impingement over the 

entire 1974 outmigration was about 12 times greater on 1/8- than on 1/4-in. 

screens. 

lhe Washington State Department of Fisheries estimates that the number 

of chinook outmigrants passing HGP in 1974 was 5.56 milli~n.'~)Of this 

total, 1.61 million were 0-age chinook emerging from redds between the 

intake and Priest Rapids Dam. The total impingement loss to this salmonid 

resource,as a result of the entire intake being at 1/4- or 1/8-in. screens 

in 1974, would have been <O.l and 0.9%, respectively. 

Experimental releases of rainbow trout in 1974 support the estimated 

impingement of naturully occurring chinook. Number and size of marked and 

unmarked rainbow trout impinged by 1/4- and 1/8-in. traveling screens are 

presented in Table 9. The half of the intake with 1/4-in. screens impinged 

49 fish, representing 0.25% of the 20,000 unmarked fish released 500-601) yd 

30 
ln 

P 

S N -7 

m 

c9 m 

TJ m m c

la 

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22.

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\ -

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0 P cu 

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31 
. 1 

upriver from the intake. Assuming equal numbers would be impinged at each 

half of the intake ifscreens on both sides were of 1/4-in. openings, it is 

estimated that 0.5% would be impinged. Since 60% of the natural outmigrants 

move down the sides of the river(6) and conservatively assuming equal numbers 

on each side (30%) these data indicate that 0.15% of the outmigrants emerging 

from redds between HGP and Priest Rapids Dam would be impinged on the 1/4-in. 

screens. The half of the intake with 1/8-in. screens impinged 280 fish or 

1.4% of the 20,000 fish released. Using the same assumption (equal numbers 

impinged on each half), 2.8% of the released population would be impinged 

with the entire intake using screens of 1/8 in. Assuming equal numbers of 

outmigrants on each side of the river, 0.84% of the outmigrants emerging 

from redds between HGP and Priest Rapids Dam would be impinged on the 1/8-in. 

screens. 

Impingement was 5.7 times greater on 1/8-than on 1/4-in. screens for 

fish released upriver and 5.3 times greater for those released in front of 

the screens. The difference between these values and the 12-fold impingement 

increase on 1/8-in. screens for natural chinook populations may reflect a 

species difference. Young 0-age rainbow trout are deeper-bodied than naturally occurring 0-age chinook and impingement on 1/4- and 1/8-in. screens 

may not be the same for each species. 

The 1/4-in. screens impinged 2% of the fish released behind the curtain 

wall and in front of the traveling screens, while 13% were impinged on the 

1/8-i1-1. screens. These values, however, do not simulate outmigration and 

therefore, they reflect only the relative difference in impingement potential between 1-/4- and 1/8-in. screen openings for fish behind the curtain 

wall. Additionally, comparison of impingement for fish released behind the 

curtain wall with those released upriver indicate that impingement potential 

increases for fish once they are behind the curtain wall and in front of the 

traveling screens.. Impingement potential is even greater for a fish immediately in front of 1/8-in. than it is in front of 1/4-in. openings. 

32 
Passage Through the Traveling Screens 

A large number of fish were observed inside the intake during the 1973 

outmigration. An estimate of the total number of fish passing to the inside 

was not possible for this period, alt-hough 4,869 fish were collected inside 

the intake from 29.March through 23 July 1973 (Table 10). Many of the fish 

sampled behind the screens were obviously too big (body depth >0.9 cm) to 

have passed through the 1/4-in. screen openings which are 0.64 cm on a side. 

However, a small fish with a body depth (maximum distance between dorsal and 

ventral surfaces) greater than 0.64 cm could potentially enter the intake by 

passing diagonally through the screen mesh. The diagonal opening for the 

1/4-in. screens is 0.9 cm. The largest fish sampled behind the screens was 

a sculpin (Cottus asper) which measured 2.9 (body depth) and 11.6 cm (fork 

length). These larger fish could have either entered through the screens 

at a smaller size and resided in the intake for a period of time or entered 

recently around the screens. Data on residence time obtained in 1974 and 

identification of other possible avenues of entry (discussed below) indicate that recent entry is more likely. 

TABLE 10. Salmonids and Non-Salmonids Sampled Inside the Intake Behind 

1/4-in. Screens from 29 March Through 23 July

Total

No. 

March 8 

April 1436 

hY 1851 

June 84 

July 15 

1-20 

July 23 1464 

Total 4858 

(a! F = Fintrol; DN - DiO kt 

Traveling 1393 

Salmonids Mn-Salmonids 

Fork Length Fork Length 

Avg . Total 

No. 

Avg . Range SarPD’2;

0 B - 0 MeTrvJ ’! 

3.8 3.5-4.1 0 DN 

3.9 3.2-4.9 8 3.5 3.1-4.1 ON 

4 .O 3.4-5.9 0 DN 

4.7 3.3-7.1 0 DN 

6.2 5.4-7.5 0 Dli 

6.7 5.4-8.3 -* 7.4 3.6-11.6 F.Dh 

11 

33 
-- 

-- 

-_ 

In 1973, chinook salmon (fork length range, 3.2-8.3 cm) made up the 

entire salmonid catch (4858 fish) behind the 1/4-in. traveling screens and 

99.8% of the total fish catch (Table 10). In 1974, chinook salmon again 

made up the entire salmonid catch behind 1/4-in. screens (2451 fish, fork 

length range, 3.2-13.5 cm) and 1/8-in. screens (1967 fish, fork length 

range, 3.4-12.7 cm). This species represented 98.9% (1/4-in. screens) and 

99.2% (1/8-in. screens) of the total fish catch (Table 11). Eleven nonsalmonid individuals (fork length range, 3.1-11.6 cm) were sampled behind 

the 1/4-in. traveling screens in 1973 (Table 10); in 1974, 28 non-salmonid 

individuals (fork length range, 3.2-13.5 cm) were sampled behind the 1/4-in. 

screens and 15 individuals (fork length range, 3.4-12.7 cm) were sampled 

behind the 1/8-in. screens (Table 11). The total number of .salmon collected 

TABLE 11. Salmonids and Non-Salmonids Sampled Behind 1/4- and 1/8-in.

Traveling Screens from 6 March Through 31 May 1974 

1/4-in. Screens 1/8-in. ScreE 

-.-___ Salmonids Non-Sal mon~ ids Salmonids Non-Salmonids 

Fort Lenqth ___. 

(CT~ NO. (m) (cn\ Method NO. (cmi icm) NO. (cm) (cm) Method(d) 

Yar:b :' 4.; :.a-z.o 6 3.- 3.5-4.1 F ,DN 35 4.1 3.7-4.1 5 8.3 4.0-12.7 F,DN 

A,-,..,: s?::b) 4.1 3.5-2.5 3 4.6 4.1-c.5 C.3N 456") 4.0 3.5-i.4 2 3.? 3.4-4.5 F,DN 

?!5 , 

I -> ;65 c.0 2.6-d ' D - 30 min 

Dip Net 

79 3.9 3.5% 1 32 F,il. 

3i; %! 

Fork Le3tL- Fort Length Fork Length 

Total Avg. Range Total Avq. Range Sample Total Avo. Range Total Avg. Range Sample NO. ICIP.) 

u3 L 352 4.3 3.3-5.? 1 5.6 135 di?s 292 4 9 ?.3-5.G 1 3.9 - :?5 di:; q-:4 

Ya v !_3_L1 4.1 3.5-5.: -

;6 L.: 3.2-12.5 F,DN __1255 4.2 3.4-5.5 L 4.5 4.i-4.9 ;.?'.

15-31 

. i = Firstro', :b = Dip x.7. 

. , I. .-2P*> WE'+ e- ??-;- Lc-. . a: ..' I*.)-. Sa->],"; (I$ An--:'; . .i,?. .r .,' :> 5­

in 1974 was not much greater behind 1/4-in. screens than behind 1/8-in. 

screens and estimates of total passage during the 1974 outmigration (discussed below) indicate that passage does not differ markedly with either size 

screens. 

34 
Rainbow 'trout released inside the intake and immediately recaptured by 

means of Fintrol and dipnet (i.e., no pumping) indicate the sampling method 

may be 60% efficient (Table 12). Other rainbow trout released inside the 

intake were recaptured similarly after 16.5, 19.5, and 19.75 hr of pumping 

(Table 12). Extrapolation to the abscissa of the line (Figure 12) which 

shows the percent of fish remaining in the intake at different pumping 

periods, suggests that maximum residence time of juvenile rainbow trout 

inside the intake is 22 hr. Few fish (~1%)released inside the intake passed 

to the outside and subsequently became impinged (Table 9). Although this 

number was 6 times (12 versus 2 fish) higher with 1/4- than 1/8-in. openings, 

the number of individuals involved was too small to affect estimates of 

passage losses. The data on residence time and direction of movement suggest that fish inside the intake exit only through the plant condensers. 

Survival of condenser passage is not possible due to a combination of thermal 

and mechanical stresses. Therefore, all fish passing behind the traveling 

screens are assumed to be destroyed. 

TABLE 12. Numbers of Rainbow Trout Released and Recaptured Inside 

Intake After Different Pumping Durations 

llG . No. Percent of 

Corrected 

Percent o\f 

Pumping 

Time Intake 

Re1 eased Recaptured Re1 ease Re1easda, (Hr) ___- Side __I~ 

1000 599 60 100 0 2 

1500 259 17 28 16.5 1 

1158 77 7 12 19.5 1 

1150 58 5 8 19.75 2 

(a) Correction based on sample efficiency 

35 
*I 

I 

0 5 

FIGURE 12. Percent 

After D 

Passage Estimates 

RESIDENCE TIME ONCE 

INSIDE INTAKE 

o .ACTUAL VALUES 

VALUES CORRECTED FOR 

SAMPLING EFFICIENCY 

0 

I I I 

10 15 20 

HOURS OF PUMPING 

of Released Fish in the Intake 

fferent Pumping Per ods 

Estimates of passage behind 1/4- and 1/8-in. traveling screens can be 

made from experimental releases of rainbow trout. Since 188 (or 0.9%) of 

20,000 fish released upriver on the intake side were collected in half the 

intake behind the 1/4-in. traveling screens (Table 9) and with sampling 

efficiency estimated at 60%, approximately 313 (or 1.6%) of the released 

fish may pass behind the 1/4-in. screens. If the entire intake had been 

36 
fitted with 1/4-in. screens the estimate would increase to 626 or 3.1% of 

the fish released on the intake side. However, 60% of the natural outmigrants move down both sides of $he river.(6) Assuming equal numbers on 

each side (30%),an estimated 0.9% of the natural outmigrants emerging from 

redds between HGP and Priest Rapids Dam would pass behind the 1/4-in. screens.. 

One hundred three or 0.5% of the released fish passed behind the 1/8-in. 

screens. Usi.ng the same assumptions and correcting for sample efficiency, 

172 fish may have actually passed. Ifthe entire intake had been fitted with 

1/8-in. screens, about 344 (or 1.7%) of the released fish and 0.5% of the 

natural outmigrants emerging from redds between HGP and Priest Rapids Dam 

would pass behind the 1/8-in. screens. 

These data indicate that changing the screens from 1/4- to 1/8-in. 

openings reduced total estimated passage from 3.1 to 1.7% of the 'released 

fish popu-lation and 0.9 to 0.5% of the natural populations emerging from 

redds between HGP and Priest Rapids Dam. For fish released behind the 

curtain wall and in front of the traveling screens, passage was 4.6 t.imes 

greater with 1/4- than 1/8-in. openings. However, these fish do not simulate natural outmigration but merely what happens once fish are behind the 

curtain wall. As with impingement, the potential for passage increases once 

rainbow trout get behind the curtain wall and the relative differences 

between the two screen sizes becomes greater. To place these data in 

perspective, consider that the released fish (rainbow trout) are deeper 

bodied than naturally occurring 0-age chinook and may not pass the screens 

to the same extent. Chinook of the same body length are more likely than 

rainbow trout to pass through an opening of a given size. 

Since rainbow trout inside the intake apparently exit through the plant 

condensers in less than 24 hr (Table 12 and Figure 12), each of the samples 

listed in Table 13 for March, April, and May 1974 may represent 24-hr chinook 

samples. When the values for these months are considered by day and corrected 

for sample efficiency, and assuming the entire intake is at either 1/4- or 

1/8-in. openings, the estimated values can be plotted against time to show 

37 
TABLE 13. Daily Numbers of Chinook Salmon Sampled on and Behind 1/4- and 

1/8-in. Traveling Screens by Fintrol and Dip Net During Spring 

1974 

1/4-i n. 1/8-in. 

-. 

Screen Impinged Screen Impinged 

March 27 21 1 11 4 

28 15 2 (AM) ' 5 34 (AM) 

29 5 0 7 85 

30 39 0 . 12 3 

No. Behind No. No. Behind No -

total passage (Figure 13). The area under. the resulting curves for 1/4­

and 1/8-in. screens are estimates of total chinook passage with the entire 

intake with 1/4- or 1/8-in. screens from March-June 1974. An estimated 

142,000 0-age chinook would have been passed with the entire intake at 

1/4-in. and 120,000 fish if all the screens had been 1/8-in. (Table 14). 

This represents 8.8 and 7.5% of the 1974 estimated 1.61 million(9) chinook 

fry emerging from redds between the intake and Priest Rapids Dam. These 

estimates based on numbers of chinook fry collected behind the screens are 

higher than the estimates based on releases of rainbow trout. The disparity 

38 
-- -- 

---lBlN.MESH 

n 5112026 s11Zo; 

MARCH APRIL MAY 

FIGURE 13. Estimates of O-Age Chinook Screen Passage for 1974 

TABLE 14. Summary of Estimated Impacts Due to Impingement and Passage of 

O-Age Chinook Salmon with 1/4-and 1/8-in. Screens During 1973 

and 1974 

Impingement Passage To ta 1 

Impact Impact Impact ­

% O-Age % O-Age % O-Age

No. Ch iPO:: !I( (a) Chinook(b) No. (' Chi nook (b, No ___I_. __ 

1973 1/4-in. Screens 600 - <1 (e) - ­

1974 1/4-in. Screens 1,100 <1 (dl <1 (e) 141,800 1 (dl 142,800 1 (d) 9(e 

1/8-in. Screens 14,100 1 (dl 120,400 1 (dl 134,500 1 (d) 8(e 

-

(a) Based on estimates derived from screen wash samples, corrected for impinged

fish collected alive and rounded to the nearest hundred. 

(b) Fry emerging from redds between HGP and Priest Rapids Dam. 

(c) Based on estimates derived from 24 hr intake samples and rounded to the 

nearest hundred. 

(d) Based on releases of rainbow trout. 

(e) Based on estimates of number impacted and Washington Department of Fisheries 

estimates of 0.24 (1973) and 1.61 (1974) million chinook fry emerging .from 

redds between HGP and Priest Rapids Dam. 

39 
may reflect species differences in body shape and behavior. Since much of 

the estimated impact depends on residence time, and estimates from data collected for rainbow trout may not be directly applicable to chinook, it is 

possible that chinook residence time in the intake may be shorter than 

24 hr. Chinook losses in this case would be higher than the above estimates.. 

But, the data suggests that these may be worst case estimates, and that 

chinook residence in the intake may be longer than 24 hr. Comparison of the 

daily numbers of chinook sampled on and behind the traveling screens 

Table 13) indicates that the number of chinook seen behind the screens on 

April 18 and 23, and on May 28 bears little, if any, relationship to the 

number of chinook impinged on the same dates (on other dates, however, the 

magnitude of passage is similar to impingement values). The magnitude of 

passage sample sizes on April 18 and 23 and May 28 suggest that these 

fish represent an accumulation of fish over a longer period of time than 

24 hr; i.e. , residence time of chinook in the intake may be longer than 

that for rainbow trout. Hence, passage rates for chinook extrapolated from 

trout data may overestimate chinook losses. For example, if chinook resided 

in the intake twice as long (i .e., 48 hr) as trout, passage losses would be 

halved and total passage would represent about 4.5% of the chinook population loriginating between HGP and Priest Rapids Dam. To refine these values, 

it is essential to estimate chinook salmon residence time. Ongoing investigations are addressing this problem. 

During their first 3 weeks as fry, juvenile chinook salmon may pass 

the 118-in. openings. As the fry develop, however, 1/8-in. screen openings 

should prevent 0-age chinook passage. 

The appearance of fish behind the 1/8-in. traveling screens throughout 

the 1974 outmigration and the sizes of fish sampled behind both size screen 

openings indicates that fish may be entering by some other means. There are 

several possible alternative routes for fry to bypass the traveling screens 

and thereby enter the intake area other than through the screen mesh. These 

are : 

40 
t 

0 Around the screens: engineer drawings of the intake show design 

openings of up to 5/16-in. along the sides and 1 1/8-in. at the ends 

where the "Z-frame" fits into the concrete side of the screen bay 

(Figure 14). (11) 

0 Between the screen frames: the screen frames are not true, and 

openings between the frames vary greatly and in places are up to 

3/8 in. wide (Figure 15). 

Under the screen: a design opening of at least 3/8 in. exists between 

the bottom of the screen and the bottom of the intake floor. 

-= 5/16 IN.-= 

-_____ FIGURE 14.

INS1 DE INTAKE 

I NTA KE WALL 

FRONT OF TRAVELING SCREEN 

1518 IN. CLEARANCE 

BETWEEN POST AND WALL 

SECTION THRU SCREEN AND Z - FRAME 

Schematic Through One Intake Wall Traveling

Screen and "Z-Frame" 

41 

The least likely path of entry is beneath the screen. Chinook fry 

are mainly surface oriented and the majority occur in the upper few meters 

of water .(6) About 30% of the fish collected at Beyers Landing, which is 

shallower than in front of the HGP intake, were near the bottom. SCUBA diver 

observations indicate that there are deposits of silt and debris located 

along the entire outside length of the base of the traveling screens, which 

could serve to preclude passage under the screen. Additionally, attempts 

by SCUBA divers to insert a thin (1/8 in.) metal bar under the screens were 

unsuccessful, indicating that the possibility of passage of chinook fry 

under. the screens is unlikely. 

Wh-ile passage around the sides of the screen is possible, a constant 

5/16-,i.n. gap probably does not exist along the sides of the screens for 

the entire distance (60 ft) from top to bottom. According to the screen 

manufacturer it is almost impossible to pour concrete walls parallel for 

60 ft that provides a perfectly plum gap. (2) 

The most likely path of entry of small fish is through the gaps between 

the screen frames. These potential routes present considerable area to the 

fry and are capable of passing fish. Closing the gaps between the screen 

frames can,be expected to lessen fish passage. However, it may increase 

screen impingement. 

Total Impact 

In assessing the potential impact of the HGP intake with either 1/4- or 

1/8-in. screen openings on O-age chinook from the Columbia River, the total 

loss of fish from screen impingement and passage must be determined. The 

total impact has not changed if a reduction in screen passage is accompanied 

by an increase in screen impingement of equal magnitude. 

Impingement of chinook outmigrants has been estimated to be 12 times 

greater on 1/8-in. than on 1/4-in. screens. Total estimated passage of 

chinook outmigrants, however, is only 1.2 times greater on 1/4- than on 

1/8-in. screens. The total number impinged is relatively low in comparison 

43 
to the estimated total number of fish passed and, therefore, impingement 

makes a minor contribution to the total impact (Table 14). The estimated 

impingement and passage losses (total impact) with 1/4-in. screens in use 

across the entire intake during the 1974 chinook salmon outmigration are 

1100 impinged(a) and 141,800 fish passed for a total impact of about 

143,000 fish, or 9% of the 0-age chinook emerging from redds in the Columbia 

River between HGP and Priest Rapids Dam (Table 14). The total impact with 

1/8-in. screens equaled 14,100 (impingement loss) plus 120,400 (passage 

loss) or a loss of 134,500 fish or 8%of the chinook emerging from redds 

between HGP and Priest Rapids Dam (Table 14). While impingement was 

clearly greater on 1/8-in. screens, passage was not changed from that which 

occurred with 1/4-in. screens. Since impingement impacts are small in 

relation to passage, the total estimated impact was virtually the same with 

both size screen openings. 

Chinook produced between HGP and Priest Rapids Dam represent about 29% 

of a1 1 chinook outmigrants (natural and spawning channel releases) passing 

the intake. Therefore, impingement and passages losses during any one year 

may represent a maximum of 3% of the outmigrants originating from upriver 

and passing HGP. 

(a) Corrected for estimates of the numbers of impinged fish which were collected alive. 

44 
SUMMARY OF PRELIMINARY CONCLUSIONS 
SUMMARY OF PRELIMINARY CONCLUSIONS 

A study of screen impingement and passage of fish is being conducted 

by BNW at HGP. The data from March 1973 through June 1974 are reported 

here. Based on these data preliminary conclusions of this study are: 

Impact is limited almost exclusively to juvenile chinook salmon 

emerging from redds between HGP and Priest Rapids Dam. 

Peak screen impingement and passage will occur in April and May during 

the first part of the annual outmigration if the plant is operated at 

this time. Although the outmigration may continue through June, the 

fish are larger and are apparently not vulnerable to cooling water 

intake. 

0 Use of 1/8-in. traveling screens resulted in about 6 (experimentally 

released rainbow trout) and 12 times (naturally outmigrating juvenile 

chinook) greater impingement than 1/4-in. screens. 

Impingement losses of 0-age chinook salmon vary as a function of 

intake screen size, intake velocity and source of fry. The estimated 

losses in 1974 for fish emerging .from redds between HGP and Priest 

Rapids Dam are <l%for 1/4-in. and 1% for 1/8-in. screens. 

0 The impact of screen impingement was less than screen passage. While 

a few impinged fish may be washed off and survive, 100%of those passing the screens must be assumed to be killed in passage through the 

plant condensers. 

Use of 1/4-in. traveling screens resulted in 1.8 (experimentally 

released rainbow trout) and 1.2 times (naturally outmigrating juvenile 

chinook) greater passage than 1/8-in. screens. 

0 The 1974 passage losses of 0-age chinook salmon emerging from redds 

between HGP and Priest Rapids Dam were estimated to range from 

1 (experimentally released rainbow trout) to 9% (naturally outmigrat 

juvenile chinook based on a residence time of 24 hr) for 1/4-in. and 

1 (experimentally released rainbow trout) to 7% (naturally outmigrat 

juvenile chinook) for 1/8-in. screens. 

45 
0 The estimated combined impact of impingement and passage in 1974 were 

about the same for 1/4- and 1/8-in. screens, and represented 1 (experimentally released rainbow trout) to 9% (naturally outmigrating juvenile 

chinook) of the chinook salmon emerging from redds between Priest 

Rapids Dam and the intake. These losses represent about 3% of the 

total estimated chinook outmigrants passing HGP. 

0 Reducing the screen size from 1/4- to 1/8-in. has not greatly reduced 

passage. Most of the fish apparently pass the screens in places other 

than through the mesh. Three possible pathways have been identified. 

These are openings or gaps that occur 1) in the Z-frames, 2) at the 

bottom of the traveling screens, and 3) between the screen frames. 

The latter seems the most likely possibility. Closing these gaps 

should reduce passage through both size screens. This should make 

the 1/8-in. screens more effective in precluding fish passage than 

the 1/4-in. screens. Ongoing studies are addressing these questions. 

46 
REFERENCES 
REFERENCES 

1. Washington Public Power Supply System Corps of Engineers Application 

No. 071-04B-2-000570, 13 Apri 1 1972. 

2. R. H. Arrowood, Mgr. Screening Equipment, Envirex, Inc., Personal 

Communi cati on. 

3. D. L. Park, Seasonal Changes in Downstream Migration of Age-Group 0 

Chinook Salmon in the Upper Columbia River, Trans. her. Fish. SOC., 

98(2):315-317, 1969. 

4. C. D. Becker, Temperature Timing and Seaward Migration of Juvenile 

Chinook Salmon from the Central Columbia River, USAEC R&D Report, 

BNWL-1472, Battell e-Pacif i c Northwest Laboratories, Richland, WA, 

21 p., 1970. 

5. M. C. Bell, “Fisheries Handbook of Enqineerinq Requirements and 

Biol ogi cal Criteria, Fish. -Eng . Res. lProg., torps of Engineers , North Pacific Div. , Portland, OR, February 1973. 

6. E. 11. Mains and J. M. Smith, The Distribution, Size, Time, and Current 

Preferences of Seaward Migrant Chinook Salmon in the Columbia and 

Snake Rivers, Fish. Res. Papers, Wash. State Dept. Fish., 2:5-43, 

1964. 

7. Letter, Thor C. Tollefson, Director, Wash. Dept. Fish. to M. J. 

Schneider, Battell e-Pacific Northwest Laboratories, 12 November 1973. 

8. D. G. Watson, “Fa11 Chinook Salmon Population Census,” In: Ann. Rept.

for 1972, Vol. I, Part 2, Ecol. Sci., BNWL-1750. Battelle Pacific 

Northwest Laboratories, Richland, WA, pp. 6.16, 1973. 

9. R. Allen, Washington Dept. Fish., Wenatchee, WA, Personal Communication. 

IO. f.1. C. Bell, College of Fish., University of Washington, Seattle, WA, 

Persona 1 Commu n i cat i on. 

11. Rex Chainbelt Inc., Milwaukee, Wisconsin, Field Service Manual, 

Operation and Maintenance Instructions and Parts Catalog for Traveling 

Rater Screens 4 Post, The Hanford Electric Generating Project,

Richland, W.4, Washington Pub1 ic Power Supply System. 

47 
APPENDIX A 

Common and Scientific Names of Salmonids and Non-Salmonids 
-- 

-- 

APPENDIX A 

Common and Scientific Names of Salmonids and Non-Salmonids 

SALMON1DS 

Oncorhynchus kisutch (Mal baum) 

0. nerka (Walbaum) 

-0. tschawytscha (Mal baum) 

Prosopium will iamsoni (Girard) 

Salmo gairdneri Richardson 

NON-SALMONI DS 

AciDenser transmontanus Richardson 

Acrocheilus alutaceus Agassiz & P 

Alosa sapidi-1 son) 

Catostomus macrochei 1us Girard 

Cottus asper Richardson 

-C. bairdi Girard 

-C. bel di ngi Eigenrnann & Ei genmann 

-C. perplexus Gilbert & Everrnann -C. rhotheus (Smith) 

Cyprinus carpio Linnaeus 

Entosphenus tridentatus (Gairdner 

-___ Gasterosteus aculeatus Linnaeus 

-____ iepomis gi bbomaeus) 

Mylocheilus caurinus (Richardson) 

Perca f 1avescmtchi 11 ) 

PercoDsi s transrnontana Eiaenmann & 

-

__I--- Richardsonius bal teatus (Richardson 

Coho salmon 

Sockeye salmon 

Chinook salmon 

Mountain whitefish 

Rainbow (steelhead) trout 

Whi te sturgeon 

.ering Chise1mouth 

American shad 

Largescal e sucker 

Prickly sculpin 

Mottled sculpin 

Piute sculpin 

Reticu1ate scu1pi n 

Torrent scul pi n 

Carp 

Pacif ic Lamprey 

Threespine stickleback 

Pumpkinseed sunfish 

Peamouth chub 

Ye1 low perch 

Eigenrnann Sand roller 

1) Northern squawfish 

Longnose dace 

Leopard dace 

Redside shiner 

A- 1