242;0 F P - FD - M-C..;

Washington Phase II Fish Diversion Screen

Evaluations in the Yakima River Basin, 1997

Prepared by:

L. Blanton

A. Neitzel

s. Abernethy

Pacific Northwest National Laboratory

Richland, Washington

Prepared for:

s. Department of Energy

Bonneville Power Administration

Environment Fish and Wildlife

o. Box 3621

Portland, Oregon 97208-3621

Project Number 86- 118

Task Order DE-AT79-9430373BPA

Contract Number DE-AI79-86BP62611

February 1998
Acknowledgments

The successful completion ofthis project depended on the involvement and

cooperation of many people. Jodi Stroklund, Bonneville Power Administration (BP A),

directed the project. John Easterbrooks, Washington Department ofFish and Wildlife

(WDFW), provided valuable background information on the sites and also comments

on the operation and maintenance of individual sites. Bill Mavros, Brett Tiller, and

Mike Blanton ofPNNL, Associated Western Universities students Jeff Marco and Jen

Morse, and Science and Engineering Research Semester student Ginger White assisted

during field evaluations. Scott Abernethy and Bob Mueller provided valuable guidance

on equipment operation and Scott helped with data interpretation. Elementary and

high school teachers ITom Richland, Kennewick, Pasco, and Toppenish, Washington

also assisted in data collection and summarization as part of a Department of Energysponsored program entitled Partnership for Arid Lands Stewardship (PALS). Bill

Mavros and Dennis Dauble (PNNL) reviewed a draft of the manuscript.

11l
Summary

The Pacific Northwest National Laboratory evaluated 19 Phase II screen sites in the

Yakima River Basin at least three times each between April 30 and August 22, 1997.

The sites were examined to determine if they were being effectively operated and

maintained to provide fish a safe, efficient return to the river. Data were collected to

determine if velocities in ITont of the screens and in the bypass met current NMFS

criteria and promoted timely fish bypass, if fish were protected ITom injury due to

impingement, entrainment, and predation, and whether bypass outfall conditions

allowed fish to safely return to the river. A bi-directional flow meter and underwater

video system were essential in completing the investigation.

In general, water velocity conditions at the screen sites were acceptable by NMFS

standards. High approach velocities and slow bypass flow were the most common

problems noted. Although velocities often fluctuated ITom one sampling location to the

next, average sweep and approach velocities were very good. In general, fish should

not be impinged or experience delays in returning to the river under normal operating

conditions.

Most screens were properly sealed to prevent fish entrainment and injury, although

potential problems were identified at several screen sites. Three sites had gap openings

ITom the forebay to the aftbay, allowing fish to be entrained. Other sites had spaces

larger than 3/32 inch where small fish could become trapped. Some drum screens had

flat spots but these were not been confirmed as underwater gaps, primarily because of

siltation. On rare occasions, seals were intact, but cracked or turned under.

Submergence levels at the drum screen sites exceeded 85% for one third of our

evaluations. Eight of 12 drum screen sites experienced high water levels during at least

one evaluation. Only one operating site s submergence was measured at less than 65%

submergence. Two flat plate screen sites were completely overtopped with water

during one evaluation each. Although 1997 was an extreme high-water year, these

overtopping events point out that some screens do not completely protect fish under

the full range of potential operating conditions.

Water depths at the outfall pipe were acceptable at all but four sites. Generally,

water depths were low near the end ofthe irrigation season due to low river flows.

Rock removal around the outfall pipe or pipe extension would improve the situation.

We gauged the potential for predation by qualitatively measuring the types and

amount of cover provided for predators in ITont of the screens and by recording

random observations of fish large enough to be considered predators in the fore bay.

Predation was more likely to occur at drum screen sites than at flat plate screen sites.

Drum sites provide more predator hiding places because greater amounts of woody
debris accumulate under the drums and against the concrete walls that divide one

screen bay ITom the next. Four sites had both woody debris and large fish present.

These four sites were considered most likely to experience juvenile salmonid loss to

predation. . Periodic removal of woody debris ITom underneath the curvature of drum

screens would decrease the likelihood of predation at these sites.

Screens were generally well maintained. Automated cleaning brushes functioned

properly, chains and other moving parts were well greased, and inoperative and algaecovered drum screens were eventually repaired and cleaned. However, removal of

sediment build-up and accumulated woody debris are areas where improvement should

be considered. Maintenance checks should include observation of bypass outfalls on a

regular basis, as conditions at the end of the bypass pipe are likely to change seasonally,

especially in streams with high gradients or unstable gravel.

Post-season evaluations were conducted at 11 sites in November to try and confirm

seal and drum screen defects, and locations of excessive sedimentation. This proved

effective in several cases, but the winterization process eliminated some ofthe

evidence. Several forebay areas had already been cleared of silt. It was difficult to

evaluate screens and seals when the screens were in the storage position because the

screens could not be rotated. Also, two sites remained in full operation while others

were submerged, precluding detailed examination of parts still under water.

Periodic, regular screen evaluations will increase the effectiveness of screen

operation and maintenance practices by confirming the effectiveness (or ineffectiveness)

of screen operating procedures at individual sites. Where procedures are being

followed and problems still occur, evaluation results will suggest means to improve the

procedures to better protect fish at screening facilities.
Methods

Nineteen operating screen sites in the Yakima, Naches, and Tieton River basins

were evaluated between April 30 and August 22, 1997 (Figure 1).

1. Snipes- Allen

2. Union Gap

3. Taylor 4. Bull 5. Ellensburg Mill

6. New Cascade 7. Fruitvale

8. Toppenish Pump

9. Naches - Cowiche

10. Congdon

11. Gleed

12. Kelley - Lowry

13. Clark

14. Naches- Selah

15. Lindsey

16. Yakima - Tieton

17. LowerWIP

18. Bachelor - Hatton

19. UpperWIP

. Screen Site

Figure 1. Yakima River Basin Phase II Screening Facilities
Each ofthe 19 sites was visited three times. The three rounds of evaluations were

conducted during early May, late June/early July, and mid August. Three types of data

were collected. These included water velocity measurements (Figure 2), underwater

video footage, and general data (i. , screen submergence, bypass conditions, fish

presence, operator aids). During the first evaluation, video footage was not acquired

due to high water turbidity. The third evaluation was the only round during which nets

were placed immediately downstream of the screens

to capture and identifY fish found in irrigation canals.

Eleven screen sites were visited on November 20

1997. The purpose was to examine screen sites while

forebays were relatively dry. It was our intention to

confirm information ITom underwater video data

collected during previous investigations. Some

factors considered were silt and debris accumulation

seal integrity, and screen condition.

Figure 2. Underwater Video Equipment

and Water Velocity Probe.

Velocity Measurements

Equipment

Water velocities in ITont ofthe screens and in the bypass were measured with a

Marsh McBirney Model 511 (B) electromagnetic water current meter. The meter used a

bi-directional probe (Figure 3) that allowed measurement of flows in two directions

(approach and sweep) simultaneously. Output was read visually ITom a panel gage.

The probe was securely mounted to a horizontal arm that extended approximately 12

inches ITom a vertical pole. The length of the horizontal arm and its position on the

vertical pole were adjustable. The probe support assembly was positioned at least 12

inches downstream or outside the probe s sensors to minimize interference ITom the

vertical pole when taking velocity readings.

Cross Section of Probe

Clamping Surface

Cable probe

Figure 3. Bi-directional Electromagnetic Probe Used for Measuring Water Velocity
At several sites with very small drum screens, a smaller, unidirectional

electromagnetic water current meter probe (Marsh McBirney Model 2000CBJ) was used

to measure velocity because it could be placed closer to the bottom of the screen than

the bi-directional probe.

Probe Positionin

Velocity measurements were taken in ITont of all screens. The vertical pole was

placed close to the ITont of the screen, but was never in contact with the screen face.

The bottom of the pole rested on the concrete forebay floor (usually on the raised sill),

but the pole was not allowed to come in contact with metal (e. , walking platform

gantry, or girder), to reduce the likelihood of electrical interference. The probe was

mounted on the horizontal arm so that it pointed upstream and was positioned within 3

inches of the screen face. Because the screens are constructed at an angle to the canal

flow, all measurements were taken with the probe orientation parallel (sweep) and

perpendicular (approach) to the screen face, not to canal flow. Measurements were

taken across the screen face at 0.2 and 0.8 ofthe water depth. Velocity measurements

were taken at either three or five evenly spaced positions across each screen or panel.

Velocities were also measured in the bypass. Two measurements were recorded.

The first was taken immediately inside the vertical slot bypass entrance at mid water

depth. The second was recorded halfway between the bypass entrance and the

overflow weir, again at mid water depth.

Data Collection and Anal sis

Flow measurements were taken in ITont of every screen during all three site visits.

Power to drum screens and cleaning brushes was disconnected to decrease the

likelihood of electrical interference. An average:t standard deviation of the sweep and

approach velocities at each site was calculated for each visit.

Underwater Video Surveillance

ment

An underwater video system was used to investigate screen seal condition, and to

monitor debris build-up and fish presence. The system consisted of a high-sensitivity

remote camera (Sony, model HVM-352~ with a wide-angle lens (700 Sony, model

VCL-06HSCBJ). The camera was housed in a water-resistant case (Sony, model WPC1401ID) and connected by 66 feet of quadraxial cable to an 8-mm camcorder (Sony,

model CCD-FX71O Handycam Hi- 8IID) in a weatherproof housing. The case was fitted

with external weatherproof controls, a 4-in black and white monitor, and internal

battery power supply for the system. The underwater camera operates at extremely
low light levels (..::: 1 lux), so that artificial light sources were not necessary to obtain

video images during daylight hours.

Camera Positioning

The camera was securely mounted under a horizontal arm that extended

approximately 15 inches ITom a vertical pole. The length of the horizontal arm and its

position on the vertical pole was adjustable. The camera was usually angled slightly

downward to observe the area between the screen and the bottom seal where there was

a potential for finding gaps. The camera was moved ITom upstream to downstream

following the side and bottom seal/screen interfaces. Flatplate screens had vertical

seals between panels that were also observed and recorded on videotape. Where there

were signs of excessive debris or of fish presence, images were also recorded showing

the forebay area and/or bypass.

Data Collection and Analysis

Video footage was recorded only during the second and third site visits because

high turbidity (:::-6 NTU) precluded video analysis during the first round. All screens

and seals were videotaped during each of the two evaluations. Written observations

were also made when something of interest was seen (i.e. faulty seals, gaps, fish). The

videotapes were reviewed in detail using a video cassette recorder (Sony, model EVC200 Hi-8~ and a 12-in black and white video monitor (panasonic, model TR- 124-

MA lID). Images of interest were digitized using Snappy Video SnapshotlID Version 2.

software.

General Data Collection

Other data collected included:

general site descriptions and photographs

screen and seal conditions

screen submergence levels

cleaning system operation and the incidence of headloss across the screen

face

bypass flow conditions

bypass outfall flow conditions

fish presence in ITont of and/or behind screens

observations of debris in the forebay or bypass

the presence or absence of operator control aids such as water gages and

drum submergence marks on screen ITames
These data were recorded during every site visit, with the exception of fish

presence behind the screens. In August, fYke nets were placed behind screens at 9 sites

including Clark, Congdon, Ellensburg Mill, Kelley Lowry, Lindsey, Naches Cowiche

Snipes Allen, Taylor, and Upper WIP. The nets, made of 1/8 in. knotless netting, were

attached to rectangular metal ITames that could be adjusted to fit the width of the canal

or gate opening. The ends of the net were cinched shut with cable ties. The nets were

usually placed immediately behind a gate allowing water into the irrigation canal. By

shutting off the flow to all gates but the one where the net was placed, we could direct

a strong current into our net and be reasonably certain that any fish entering the canal

was captured.

The nets were put in place at mid-afternoon and checked for fish after dusk and

then again in the morning, after dawn. Retrieval took less than 10 minutes. The nets

were emptied, cleaned, and repositioned if they were to be checked again. Fish found

in the nets were identified to species if possible, and measured. Fork lengths were

recorded for all fish; head widths were recorded for very small fish. Live fish were

returned to the river ITom which they had come, below the diversion dam.
Discussion and Recommendations

Fish screens in the Yakima Basin are designed to direct fish that have been diverted

ITom a river and into irrigation canals back to the river without killing or injuring them

or delaying their migration. This study was designed to determine if screen sites are

being operated and maintained in a manner that promotes safe fish passage. Data were

collected to determine if:

flows in ITont of screens promote fish bypass without chance of delay or

impingement

screens are adequately sealed to prevent fish injury or entrainment

screen submergence levels preclude fish roll-over or entrainment, yet promote

debris removal

bypass outfall conditions promote safe fish access to the river

conditions in ITont of screens deter predation of juvenile salmonids

Water Velocities and Flows

In most instances, water velocity conditions at the screen sites were acceptable by

NMFS standards. Although velocities often fluctuated ITom one sampling location to

the next, average flows were very good. For the most part, fish should not become

impinged or experience delays in returning to the river. However, some instances

where further attention should be directed are highlighted below.

Bachelor Hatton

Nearly 13% of all approach velocity measurements at Bachelor Hatton exceeded

the 0.4 fps criteria. Approach velocities in ITont of the screen closest to the bypass

were usually highest, sometimes reaching 0.8 fps. This flow balance problem can

probably be corrected (or reduced) by adjusting porosity boards.

Water flow over the adjustable bypass weir was never set in compliance with

proper operating criteria, which suggest flow depth over the weir should be 0.9 to 1.

ft to achieve a bypass channel entrance velocity about 1.5 times greater than the

velocity in the screen structure fore bay area. Maximum depth over the weir during our

evaluations was 0.38 ft. This caused sediment buildup at the entrance to the bypass. It

also explains why bypass flows at Bachelor Hatton were always less than the average

sweep velocity in ITont of the screen structures. This condition could potentially delay

fish passage through the bypass.

During part of the summer, almost all Ahtanum Creek was diverted upstream at the

Upper WIP site, leaving the streambed near Bachelor Hatton dry. At this time the
bypass at Bachelor Hatton was blocked. This is acceptable as long as the stream is

low. However, when stream flow is adequate there should also be adequate bypass

flow and the bypass should be opened to allow for fish passage.

Bull

More than 36% of all approach velocity measurements at Bull exceeded criteria.

The maximum approach velocities measured were 0.6 fps. High velocities were

recorded in ITont of both panels, both at 0.8 and 0.2 ofthe water depth. It may be

possible to adjust the baffles behind the screen to reduce approach velocities.

Cone:don

The mean approach velocity for the Congdon site was just 0.41 fps, but there were

values recorded as high as 0. 8 fps. Just over 31 % of all approach velocity

measurements exceeded criteria. High values were recorded in ITont of all three

screens. Generally, the highest values were recorded at the upstream end of each

screen. Although both high submergence and high approach velocities occurred at this

site, review of usage/withdrawal rates did not indicate that more screen area is needed

to meet NMFS criteria.

Fruitvale

Nearly 13% of all the approach velocity measurements recorded at Fruitvale

exceeded criteria. The highest velocities were recorded in ITont of the panel furthest

upstream. The maximum value recorded was 0.65 fps. Slight adjustment ofthe baffles

behind the upstream panel could be made to reduce flow through this section of the

screen.

Toppenish Pump

Toppenish Pump had the highest percentage of approach velocity values that

exceeded criteria (43%). The average approach velocity at this site was 0.46 fps.

Conditions were most favorable to safe fish passage during the August evaluation when

approach velocities averaged only 0.31 fps. Differences noted between this evaluation

and those previous were that porosity boards behind the four most upstream screens

had been removed and that the screen furthest upstream had been cleaned and was

operational.

Union Gap

Bypass flows at Union Gap were always slower than the average sweep velocity in

the screen structure fore bay area. According to the operating criteria, adequate water
was flowing over the bypass weir. Bypass flow was fast, compared to other sites

evaluated, however it was sluggish in relation to the site s average sweep velocity.

This does not promote rapid movement of fish into the bypass. It may be necessary to

increase bypass flow requirements at this site or make other adjustments to bring this

site into compliance.

Upper WIP

Nearly 18% of all approach velocity measurements at Upper WIP exceeded 0.4 fps.

These high flows were all recorded during June and July. The fastest velocities

occurred in ITont of the screen furthest upstream, although velocities exceeding criteria

were recorded in ITont of all four screens. During June and July, bypass flows were

extremely low compared to sweep velocities in ITont of the screens. This probably

contributed to the increased approach velocities. Bypass flows may have been slow

because of blockage at the outfall. Rocks that had accumulated near the end of the

pipe due to streambed shifting were removed after data was collected in July. Bypass

flows improved immediately.

Yakima Tieton

Almost 11 % of all approach velocity measurements at Yakima Tieton exceeded

criteria. Approach velocities were high (up to 0.8 fps) in ITont of the six upstream

panels. Baffles behind these panels should be adjusted to create slower, more uniform

flows through the screen.

Seals

Most screens were properly sealed to prevent fish entrainment and injury, although

gaps were identified at several screen sites. Some gaps are open ITom the forebay to

the aftbay, allowing for fish entrainment in the canal. Other gaps were spaces larger

than 3/32 inch where small fish can become stuck and face potential injury or death.

Some drum screens had flat spots that were visible above water but could not be

confirmed underwater, primarily because of siltation. In this case, a little sediment may

be a good thing if it blocks a potential entrainment pathway. On rare occasions seals

were cracked or turned underneath the drum screen ITame. Sites with gaps or other

seal problems are identified below. Again, screens are numbered starting with the

screen furthest upstream.

Bachelor Hatton

Gaps between the screen and the bottom seal large enough for fish to become

entrained were observed with the underwater video system at Screens 2 and 4. It was

unclear whether the rubber seal or the drum shape was the cause, but the gaps should
be sealed prior to the 1998 irrigation season to protect juvenile salmonids ITom

entrainment.

Cone:don

A gap between the screen and the bottom seal large enough for fish to become

entrained was observed with the underwater video system at Screen 3. Flat spots

observed in Screens 1 and 2 may create gaps along the bottom seal, although this was

not apparent with the underwater video camera.

Ellensbure: Mill

A small hole exists between Panels 1 and 2 where they meet at the bottom. Panel 2

was installed slightly higher than Panel 1. It is unclear whether the hole was open all

the way through to the opposite side, but any small gap big enough for a fish to enter is

a potential injury site.

Gleed

Impacts ITom large woody debris at Gleed have damaged some screen material.

Screen 4 wires have been bent enough to allow entrainment of small fish. The other

screens should be examined closely to make sure they do not have gaps as well, if

screen material replacement does not occur prior to the 1998 irrigation season. The

screen material currently used at Gleed did not meet NMFS guidelines for mesh

opening sizes and may not provide enough entrainment protection for bull trout

(Salvelinus malma) and resident rainbow trout/steelhead (Oncorhynchus mykiss)

stocks.

Naches Selah

Sealant appeared to be missing along the bottom seal in several places, including

areas under Panel 1 , between Panels 1 and 2, and between Panels 3 and 4.

New Cascade

A gap between the screen and the bottom seal, large enough for fish to become

entrained, was observed with the underwater video system at Screen 7. Flat spots

observed in Screens 6 and 8 may have created gaps along the bottom seal, although this

was not apparent with the underwater video camera.

Snipes Allen

Flat spots were observed in Screens 1 and 2 that may have created gaps along the

bottom seal, although this was not apparent with the underwater video camera.
lor

Small flat spots were observed in Screens 1 and 2 that may have created gaps along

the bottom seal. Also, a stick may have punctured one side seal (not identified by

screen number), as was shown in Figure 8a.

enish Pum

The upstream seal at Screen 2 was folded underneath the metal ITame. All side

seals at this site appeared to be too short to adequately span the distance between the

ITame and the drum. Replacing the side seals for every drum screen with wider ones

would ensure that other side seals do not turn under in the future. Underwater video

also showed what appeared to be a cracked side seal (not identified by screen number),

as was shown in Figure 9.

er WIP

Underwater video footage at this site showed a small fish caught in the crack

between the screen ITame and concrete divider at the downstream end of Screen 3. 

may be advisable to seal these gaps with a "soft" seal that is not permanent and that

would not hinder raising the drums for storage in the fall, if further evidence of fish

injury or death in these small cracks is uncovered.

Submergence

Submergence levels at the screen sites often exceeded 85%. High water levels

occurred across the three site visits, not only during the period of high Spring runoff, as

shown in Table 7. Eight of 12 drum screen sites experienced high water levels during

at least one evaluation. This creates an opportunity for small fish to be carried over the

screens and down the canal. Only one operating screen site s submergence was ever

measured at less than 65% submergence. This can keep a screen ITom properly selfcleaning although this screen site appeared to be ITee of small debris. Two flat plate

screen sites were completely overtopped with water during one evaluation each.

Although 1997 was an extreme high-water year, these overtopping events point out

that some screens do not completely protect fish under the full range of potential

operating conditions. Although it may not be practical using physical barriers to

completely prevent entrainment under extreme conditions, every reasonable effort

should be made to locate and construct facilities to protect fish during spring ITeshet

conditions. Fish swimming at the water surface could easily enter the irrigation canal

during these periods.

Drum screen sites that were observed exceeding 85% submergence are Clark

Congdon, Kelley Lowry, Lindsey, Lower WIP, Naches Cowiche, Snipes Allen, and

Taylor (Table 7). The site that was less than 65% submerged was Lower WIP on

4/30/97.
Flat plate screen sites that were overtopped were Bull and Fruitvale (Table 7).

It is highly recommended that marks indicating the range of preferred submergence

levels be painted directly on at least one drum screen ITame at each site. Operations

personnel can then easily determine when a screen is outside the range and make

adjustments to headgate settings, porosity boards, or submergence gates (if present) to

keep it operating properly and to keep fish out of the irrigation canal.

Table 7. Evaluation Periods When Screen Sites Exceeded 85%

Screen Site Period 1 Period 2 Period 3

(April and May 1997) (June and July 1997\ (Au!!:ust 1997)

Drum Screens

Clark

Congdon

Kelley Lowry

Lindsey

Lower WIP

Naches Cowiche

Snipes Allen

Taylor

Flat Plate Screens

Bull

Fruitvale

Bypass Outfall Conditions

Water depths at the outfall pipe were acceptable at all but four sites. Clark

Fruitvale, Lindsey, and Upper WIP all had shallow water depths at the pipe exit during

at least one evaluation period.

Water depths were low at Clark, Lindsey, and Upper WIP near the end of the

irrigation season due to low river flows. However, fish movement in August is usually

low and the impacts of shallow water at the bypass outfall are probably negligible.

Usually, just a small amount of rock removal around the area next to the outfall pipe

would greatly improve the situation. Water was low at Fruitvale at the beginning of the

season. A one-foot pipe extension would ensure that fish were safely returned to the

creek.

Bypass pipes were often a smaller diameter than recommended by NMFS. The

WDFW and BOR have largely disregarded this criterion because they feel it adds

unnecessary cost to the projects (Easterbrooks, pers. comm.). Because the sites have
trashracks that keep out the large floating debris, these agencies assume that even the

smaller pipe diameters will be able to pass the design bypass flow and any debris likely

to enter the pipe. We did not observe any bypass pipe blockages during our

evaluations. The Lower WIP site, however, did appear to back up water near the pipe

entrance. The pipe diameter was measured at just eight inches. Further evaluations

should monitor bypass flow at this site, as results ITom this year s studies are not

definitive. Should this pipe size prove to slow fish passage to the river, installation of a

wider pipe should be considered.

Predation

Predation of juvenile salmonids at a screen site would be difficult to measure

without employing additional expensive and labor-intensive methods of observation.

Instead, we gauged the potential for predation by qualitatively measuring the types and

amount of cover provided for predators in ITont of the screens and by recording

random observations offish large enough to be considered predators in the forebay.

Predation is more likely to occur at drum screen sites than at flat plate screen sites

because there are more hiding places for large fish to hide at these sites. For example

greater amounts of woody debris tend to accumulate underneath the curvature of the

drums and against the concrete walls that divide one screen bay ITom the next. Screen

sites with excessive woody debris were Bachelor Hatton, Congdon, Naches Cowiche

New Cascade, Taylor, Toppenish Pump, and Upper WIP.

Woody debris was also observed in the bypass at Naches Selah and in ITont of screens

at Gleed. The debris at Naches Selah could be considered good cover for predators

but the water velocities at Gleed are high and therefore not conducive to fish lying in

wait, making predation unlikely.

Relatively large fish, some of which were potential predator species, were observed

with the underwater video camera in the forebays of Bachelor Hatton, Ellensburg Mill

Naches Cowiche, New Cascade, Toppenish Pump, and Upper WIP.

Thus, sites that had both woody debris and large fish present were Bachelor Hatton

Naches Cowiche, New Cascade, Toppenish Pump, and Upper WIP. These four sites

should be considered most likely to experience juvenile salmonid loss to predation.

Periodic removal of woody debris ITom underneath the curvature of drum screens

could help decrease the likelihood of predation at these sites.
Operations and Maintenance

Screens were well maintained at most sites. Automated cleaning brushes

functioned properly, chains and other moving parts were well greased, and inoperative

and algae-covered drum screens were repaired and cleaned. However, removal of

sediment build-up and accumulated woody debris are areas where improvement should

be considered. Sediments blocking the flow of water through the screen can affect

sweep and approach velocities and contribute to the increased incidence of screen

submergence above 85%. Woody debris that has lodged underneath the curvature of

drum screens cannot be seen ITom above water, but should be removed regularly.

Sticks and logs affect flow past the screens and provide cover for piscivorous fish.

They can also potentially block bypass pipes.

Maintenance checks should include observation of bypass outfalls on a regular

basis, e.g. weekly. Often, the removal of small rocks ITom the outfall area dramatically

improves bypass flow and increases the water depth ITom the outfall pipe to the

channel, allowing fish safe passage ITom the bypass into the river. Conditions at the

end of the bypass pipe are likely to change seasonally, especially in streams with high

gradients or unstable gravel. It is also possible that blockages at the end of the bypass

pipe could be diagnosed behind the ramp in the fish bypass structure. A visual aid at

the bypass structure could identifY when a problem at the outfall exists.

Screens were not always operated according to established operating procedures.

Bypass flow was not always adequate, and screens were over and under-submerged.

We sometimes encountered operations personnel at the sites. Generally, they corrected

bypass flows but did not concern themselves with screen submergence. Changes to the

screen system were often made subjectively. Gates were opened and closed until water

flows "looked right", not until a particular operating criterion was met. Again

submergence marks on drum screens and marks on the overflow bypass weirs

indicating how much water is cresting over the top would be a simple means to

enhance compliance with operating procedures. Since screen tenders keep a log of

activities, information about submergence and bypass flow could be more easily

documented if operator aids were present. 

Table 8 summarizes the areas where attention should be directed to improve fish

bypass at individual screen sites.
Table 8. Summary of Problem Areas at Individual Screen Sites

Drum

Screens

Vertical

Plate

Screens

Screen Site

Bachelor Hatton

Clark

Congdon

Kelley Lowrey

Lindsey

Lower WIP

Naches Cowiche

New Cascade

Snipes Allen

Tavlor

Toooenish Pumn

Upper WIP

Bull

Ellensburg Mill

Fruitvale

Naches Selah

Union Gao

Yakima Tieton

Vertical Gleed

Traveling

Screen

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Conclusion

Planned future work includes monitoring most or all of these 19 sites again in 1998.

Two consecutive years of data collection should provide an indication of trends in

water flow patterns, excessive debris and siltation problems, bypass outfall conditions

and more. Also in 1998, nets will be set behind screens during early evaluations (early

May and late June) to capture juvenile salmonids soon after hatching, when they are

smallest and most likely to be entrained.

These screen evaluations are valuable because they provide information that can

substantiate the effectiveness of screen operations and maintenance practices for

protecting fish. Water velocity measurements and underwater video evaluations also

expose areas of concern or potential problems that routine maintenance does not

typically reveal.

Also, in the case of new or modified screen sites where operating procedures have

not been refined, detailed evaluations can pinpoint areas where the procedures may

need to be altered. For example, where operating procedures are in place and being

followed but approach velocity, bypass flow, or other parameters do not fall within

NMFS criteria, evaluations will identifY the problem areas and alert screen operators

that the reasons for noncompliance should be investigated. For example, actual canal

water usage might be examined to confirm that irrigators are not drawing more water

than they are allowed. If all possibilities have been explored and no reasons for the

problems are found then operating criteria should be modified to meet NMFS criteria

and to protect fish.

An ideal fish screening program combines routine operations and maintenance with

a monitoring program to evaluate the effectiveness of these practices at protecting fish

at individual screen sites. By including water velocity and underwater video

evaluations in the process, the greatest protection will be provided for fish.
Methods

Nineteen operating screen sites in the Yakima, Naches, and Tieton River basins

were evaluated between April 30 and August 22, 1997 (Figure 1).

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