1020

JUVENILE ANADRAMOUS FISH PROTECTION

juvenile fish for the following reasons:

ABSTRACT

1. The drum screens at Chandler and Roza were placed at right angles tothe canal flow; therefore, there was no movement of water to direct the fish towards the bypass system. The velocity of approach to the

screens was on the order of 1. 5 ft/ s (0. 45 ml s), which was too swift

for many of the smaller juveniles and they became exhausted and then

impinged on the drum screens. The bypass systems were inadequate as

the entrances to the bypasses were usually pipe openings instead of

bays open to the full water depth, which usually resulted in an

inadequate capacity to attract the fish towards the bypass.

PROTECTION OF JUVKNILE ANADROKOUS FISH

Thomas R. Haider

Philip H. Nelson

Protection of juvenile anadromous fish (salmon , steelhead, etc. ) during their seaward migration is a major concern in the Pacific Northwest. The existing screening structures at the head end of power and irrigation canals have been only moderately successful; therefore, the

Bureau of Reclamation in conjunction with various local and national fishery agencies has developed an improved screening structure to divert the juveniles back to the river. These facilities are currently

or will soon be under construction on the Yakima River in the state of

Washington, and the Umatilla River in the state of Oregon.

The existing screening structures were placed at right angles to the flow , had excessive velocity through the screens, and utilized

inadequate bypass flows; therefore they did not provide safe passage

of the juvenile fish back to the river. The improved design positions the screens at a skew angle to the canal centerline to assure an

adequate sweeping velocity to move the juvenile fish to bypass bays before they become exhausted and impinge on the screens, provides adequate screen area for proper approach velocity, and provides increased bypass capacity to attract the fish to the bypass bays.

Close attention was also given to other factors, such as alignment of the canal upstream of the screens and certain geometric relationships,

which are critical to the proper operation of the screens.

2. At Three Mile, louvers were used in lieu of drum screens and at

Kittitas, a bar rack on the headworks was in theory supposed to serve

similar to louvers. The efficiency of these systems was extremely low.

The current designs were developed cooperatively between the Bureau of

Reclamation, the National Marine Fisheries Service, the Washington State Department of Fisheries, the Oregon Department of Fish and

Wildlife. the Yakima Indian Nation, and the Confederated Tribes of the

Umatilla Indian Reservation. The fishery agencies provided the basic

fish related criteria while the Bureau of Reclamation developed the designs based on these criteria and conducted model studies for

verification of assumptions.

The basic screening system includes the drum screen structure; a bypass

system, including a river return pipe and outlet structure; and adownstream control structure to assure a proper water surface at the

drum screen structure. A trashrack structure is provided if there are

no trashracks on the canal headworks structure- Also, a pump back

system and/or a juvenile evaluation facility may be included in the

designs, if required. Although the structures at each screen location

are site specific, the following "generic" or basic set of criteria was

developed.

Other features addressed include a trashrack structure to protect the

screens: a pumpback-bypass structure, if flows in the river between the

point of diversion and the point of fish bypass return are critical: a

juvenile evaluation facility, if required; and a river return system to safely return the fish to the river.

TRASBRACK STRUCTURE

INTRODUCTION

If a trashrack structure is required it will be placed upstream of the

drum screen structure normal to the canal flow. The width of the

trashracks is based on an approach velocity of 2 ftls (0. m/s). The bar spacing is based on the size of the trash in the canal. The

trashracks are placed on a 1: 1 slope for ease of manual cleaning. If the trashracks are to be cleaned with an automated trash rake, the

trashracks are placed on a 1/4:1 slope. If the trashracks are to be

removed for winter operation, and there is a potential sediment

problem, then they are designed to end approximately one-third the

water depth above the bottom of the canal. The trashracks are

fabricated in sections to facilitate removal and storage during winter

operation.

The existing screening structures, built prior to 1955, placed near theheadworks of the Chandler and Roza Power/Irrigation Canals and the

Kittitas Main Canal on the Yakima River in the state of Washington and

at the Three Mile Falls Diversion Dam on the Umatilla River in the

state of Oregon have proveIT to be inadequate for the safe passage of

*Thomas R. Haider , Bureau of Reclamation,

D-274, PO Box 25007 DFC, Denver CO 80225.

*Philip H. Nelson, Bureau of Reclamation,

D-253 , PO Box 25007 DFC, Denver CO 80225.

Engineering & Research Center DRUM SCREEN STRUCTURE

Engineering & Research Center For the screening structure to operate

given to the following details:

as desired, attention must be

532
534 WATERPOWER ' JUVENILE ANADRAMOUS FISH PROTECTION

DIMENSIONS OF THE DRUM SCREENS The diameter of the drum screens

should be set so that approximately 70% to 80% of the drum screen is

submerged in the water during normal operation. The drum screens

The drum screens are covered with may impinge on and be carried over the drum screens.

should never be submerged more than 90% as the very small juvenile fish

4 by 4 mesh, cloth, O, 105-inch-diameter wire (3. 68 mm clear

diameter wire), with a 33, 6% opening. This

juvenile fish from passing through the screen.durable enough to withstand winter operation and wi thout damaging the cloth.

stainless steel wi 

opening with 2. 67 rom- fabric prevents small

Also this screen is

may be walked on

Intermediate Bypass Bays and Blanks

Drum Screen Structure

Because of the possibility of winter operation the drum screens are

designed for as-foot (1. 5 m) head differential in the event icingoccurs. The gantry crane is designed to automatically pull one drumscreen if the differential becomes too great, On these proj ects all the screens are 12 feet (3, 66 m) long regardless of their diameter to facilitate transportation and to keep possible ice loads at a reasonable value,

Ct. Chandler Cana I

Flow

SKEW ANGLE - The drum screen structure should be skewed 15 to 17,

degrees from the canal centerline, as shown on Figures 1, 2, and 3. This will provide a sweeping velocity along the face of the drum

screens of about 1, to 1, 9 ft/s (0, 5 to 0, 58 m/s) when the velocity

normal to the drum screens is 0. 5 ft/s (0. 15 m/s), The sweepingvelocity is essential in moving the juvenile fish towards the bypass

system,

Access Ramp J / :l Bypass Bay 

Bypass PiPes

 /

Gravity Bypass ,

/ /

from Pump sump 7 /

if"";!' 

""oot'" """"

I ..---7River Return Pipe

/..

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rrdLIiJ 

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pumpback

Bypass

VELOCITY OF APPROACH The velocity of approach normal to the drum

screens is to be no greater than 0. 5 ft/ s (0 . 15 m/ s), The area used tocompute this velocity shall be the vertical projected area of the drum

GEOMETRY INTO AND OUT 

screen, not including the area occupied by the side or bottom seals.

OF THE DRUM SCREEN STRUCTURE - The geometry into and out of the drum screen structure is very important to maintain

equal flow through all of the drum screens. Model studies show thatthe following items contribute to this equal flow.

30' 

Y' 162030

EDIATE INTERM TYPICAL BYPASS 

.

YA K IMA turn Pipe d) 

............../

River Re (Submerge 

Outlet SECTION THROUGH TYPICAL SUBMERGED OUTLET I. There should be no curves or abrubt variations in cross section in

where T is 

the canal for a distance of 20T+ upstream of the drum screen structure,

the width of the ~anal prism at the water surface. This will assure a relatively uniform flow across the canal prism at the

drum screen structure and, therefore, equal flow through the drum screens. If a curve is too close to the drum screens there may be reduced or even reversed flow through the first or second drum screen

which will result in an increased flow through other screens on the

system. An abrupt change in the cross section just upstream of the

drum screens can also cause nonuniform flow through the screens. If it

is impract ical to have a straight section of canal this long in front

should be investigated. of the drum screen structure then some means of producing uniform flows

A model study is one means of determining an

appropriate solution. Another possibility, if a trashrack structure is required , is to place stoplogs in a pattern that produces the desired

GENERAL PLAN - CHANDLER

(TWENTY- FOUR 13 " DIA. 12 " LONG DRUM SCREENS)

50 0 50 100 150

,..,, 

SCALE OF FEET

Figure I
xisting Fish Ladders ~

------ R Engine GeneratOr/storage

JII~ 

YAKlrvtA Juvenile Evaluation FaC ility

--Ex isting Easton Divers ion Do m 

.,,/ 

River Return Pipe

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~Rlver ypass Ipes 

p

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- c-

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ROH'OOd

~ Existing Siphon 40 0 40 BO 120 '60

SCALE OF FEET 

 

Drum Screen Structure

GENERAL PLAN-KITTITAS ~ExistingKittitasMainCanal

(EIGHTEEN 13 " oiA. x 12 " LONG DRUM SCREENS) Bypass Bay

anol Flow

TYPICAL TRANSITION INTO SCREEN STRUCTURE

SECTION THROUGH

OUTFALL OUTLET

a-,

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Drum Screen Structure Check Structure

Pumpback- bypass

...,

ti"g H"dwo," Goto H'"" 

Existing Fish Ladder 

!

River Return Pipe

. /

River Return Pip

Outlet (Outfall)

Plunge Pool 

Fish Ladder Entrance stoplag

Attraction Water Inlet Grooves

UMATILLA RIVER i-Fish Ladder Exit 

. . , . . . .. .

rest Existing Three Mile

Falls Diversion Dam SECTION

THROUGH DRUM SCREEN

GENERAL PLAN - THREE MILE FALLS

FOUR 9 " DIA. 12 " LONG DRUM SCREENS

LE OF r ET 

Juvenile Evaluation Facility

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538 JUVENILE ANADRAMOUS FISH PROTECTION 539 WATERPOWER '

flow. swim against the current in front of a drum screen for longer than 2

minutes before a bypass bay is reached. Model studies have shown that the angle of the training wall should be at a slightly different angle

than the skew angle, as shown on Figure 1. Also shown in Figure 1, there should be a wider pier at this location to assure full flow

an 

When two or more bypass bays are required, the bypass pipes shall enterthrough the drum screen just downstream of the training wall,

upwell prior to entering the pump back structure or the juvenile

evaluation facility. The volume of the upwell, in ft3 . (m3), is 8QH,

where Q is the bypass capacity in ft3/s (m3/s) and H is the velocity

head in feet (m) of V2/2g. To maintain equal flow through each bypass,

individual adjustable weirs are required. The lifting device on the adjustable weirs will have a yoke such that no stems will be in the flow.

Without a model study this becomes a trial and error solution.

2. By using a transition or a blank wall, the first drum screen couldbe placed approximately one screen width downstream of the theoreticalfirst drum 

intersection of the water surface on the canal bank and the face of the

screen, as shown in Figure 2. This will help to achieve

3. The full flow through the first drum screen.

channel sides upstream and downstream of the drum screen structure must be parallel to each other for the length of the drum screen structure, This will help keep the flow uniform as the water

INTERMEDIATE PIERS

moves through the screens.

The piers between the drum screens , or the

intermediate piers, will take the shape of the drum screen on the upstream side , as shown on Figure 3. The piers take this shape so there are no obstructions in the path of the juvenile fish as they are swept along the face of the screens and past the pier noses, and to eliminate areas for predator fish to occupy. Stoplog grooves are provided downstream of the drum screens to allow for flow control in

the event there is unequal flow through the drum screens. This is

another way of producing the uniform flow desired, but as with the

install a bulkhead gate in the absence of a model study. Also, the stoplog grooves are used to

stoplogs at the trashrack structure, becomes a trial and error solution

in case a drum screen is removed for an

emergency situation,

RIVER RETURN PIPE The interior of the river return pipe and all

joints between pipe sections must be smooth. The fishery agencies

prefer PVC pipe with a second choice being mortar lined steel pipe,

The fishery agencies also prefer large radius bends in the range of 10

pipe diameters if bends are required. The flow in the pipe may be as high as 15 ft/ s (4. 6 m/ s) but no hydraulic jump will be allowed in the pipe. If there is an excessive head differential between the canal and

the river then there must be intermediate downwells between the canaland the river or there must be an outfall at the river. If downwells

water depth should be 5 to 6 feet (1.are required, the drop should be no greater than 10 feet (3 m) and the

5 to 1. 8 m),

RIVER RETURN PIPE OUTLET - The two basic types of river return pipe

outlets are the submerged pipe outlet and the outfall type outlet, 

The

submerged pipe outlet must be set to be submerged for all riverflows,as shown on Figure 1. The outlet area should have a volume similar to an upwell and must be arranged such that flow is passing through this area at all times so the juveniles are swept out minimizing the

problems associated with predator fish. It is best to put this type outlet in a portion of the river where the water is moving relatively fast. If an outfall is used, as shown on Figure 2, there should be a

pool of adequate depth below the outfall. The most important

consideration is to spread the water at the outfall as much as

possible, while maintaining at least a D, foot (0. 15 m) flow depth at

the outfall. This will break up the water entering the plunge pool andminimize the problems associated with the shear zone of a jet entering quiet water, The distance from the maximum operating pool water surface to the bottom of the drop structure should be a minimum of feet (3 m) so adults jumping do not hit the bottom of the outlet. Also, the end of the outlet must be far enough from the riverbank so

the adults that jump do not beach themselves.

THE BYPASS BAY

BYl'ASS SYSTEM

- The bypass system begins with the bypass bay at the

downstream end of the last drum screen or at the appropriate intermediate drum screen. This bypass bay should be a vertical channel 2 feet (0. 6 m) wide that is open to the full water depth. The velocity

into the channel is 2 ft/s (0. 6 m/s), which is approximately the same

as the sweeping velocity along the drum screens. The capacity of the bypass will be that required to produce the 2 ft/s (0. 6 m/s) velocity.

installation of a A set of vertical slots may be placed at the entrance of the bypass for vertical orifice if a reduced bypass capacity is

required. In this way the 2 ft/s (0, 6 m/s) velocity into the bypass may be maintained with the reduced bypass capacity, When moving from

the bypass channel into the bypass pipe, the velocity should gradually increased from 2. 0 ft/ s (0. 6 m/ s) in the channel to a higher velocity as the water either passes into a downwell or directly into

the bypass pipe, The purpose of this is to move the fish into the faster velocity water before they realize the velocities are

increasing, since the juvenile fish tend to avoid sudden changes in velocity by moving back upstream. When going into the pipe a square- to-round or rectangular-to-round transition should be used with theleading edges rounded with an approximate 0. 5-foot CO. 15 m) radius, DOWNSTREAM CONTROL STRUCTURE

If the canal diversion is large and a sizeable number of drum screens

are required, then intermediate bypass bays will be required. As a general rule the bypasses should be spaced such that the travel time along the screens is no longer than 2 minutes, so no fish will have to

There should be a control downstream of the drum screen structure tomaintain the desired water surface at the drum screens as the flow

capacities in the canal change, It is important that the water surfaceat the drum screens remain fairly constant for proper operation of the

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540 WATERPOWER '

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Figure 4

JUVENILE ANADRAMOUS FISH PROTECTION

bypass system, Also, if the water surface gets below one-half a drum

PUHPBACK SYSTEM

this trash must then move through the bypass system.

diameter, the small trash will not be picked up on the drum screens and

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A pump back system is required if the existing canal section is too

flow between the point of the diversion and the point 

small to carry the required canal and bypass capacities or if the river the river return

The pumpback system basically 

outlet is reduced below that required for adult upstream migration.

consists of traveling water screens, on

the side of the bypass channel, that will bleed off the water not

required for returning the fish to the river, and pumps located

downstream of the traveling water screens. This 

water is then pumped

into the canal downstream of the drum screens. Pumpback facilities areshown on Figures I, 3, and 4. The approach velocity normal to the traveling water screen is 0. 5 ftls (0. 15 m/s), the same as for the drum

screen. Experience has shown that a continuous wire cloth water screen

works better than traveling water screens fabricated with steel frame

baskets. This is due to the requirement of tight seals and no openings

greater than 1/16 inch (1. 6 rom). A gated gravity pipe comes out of thepump sump downstream of the traveling water screen to return 

the water

Any juvenile evaluation facility required by 

JUVENILE EVALUATION FACILITY

the canal.

to the river if the pumps shut down or if this water is not required in

fishery agencies will

probably be a custom design as the requirements for these facilities

vary greatly from site to site. If a minimum evaluation facility is

adequate then an inclined screen, an adjustable weir for water level control, and a separator for separating trash and adult fish from the

juvenile fish, is placed in the bypass channel. Any time a juvenile

evaluation system is required it is important to maintain a constant

operating water surface at the drum screens, as this affects the water

A basic 

CONCLUSIONSlevel control in the juvenile evaluation facility.

generic model of a screen structure to protect juvenile

anadromous fish may be developed, but experience gained during the

designs of the aforementioned sites has 

shown that all facilities are

somewhat site specific. The work on the Chandler system 

(Figure 1) the

Kittitas system (Figure 2) and the Three Mile Falls System (Figure 3)

are all variations of the basic drum screen system with some site

specific considerations, but, the work on the Roza system (Figure 4),

with the " saw-tooth" configuration on the drum screens, is a complete site specific design that required an independent model study.

Therefore, each site must be addressed based on its own merits and a

system devised to satisfy the specific site conditions and all fish related criteria.