1020JUVENILE ANADRAMOUS FISH PROTECTIONjuvenile fish for the following reasons:ABSTRACT1. The drum screens at Chandler and Roza were placed at right angles tothe canal flow; therefore, there was no movement of water to direct thefishtowards thebypasssystem.The velocity ofapproach to thescreens was on the order of 1.5 ft/ s (0.45 mls), which was too swiftfor many of thesmaller juveniles and they becameexhausted and thenimpinged on the drum screens.The bypass systemswereinadequate asthe entrances to thebypasses were usually pipeopenings instead ofbays open to the fullwaterdepth, whichusuallyresulted in aninadequate capacity to attract the fish towards the bypass.PROTECTION OF JUVKNILE ANADROKOUS FISHThomas R. HaiderPhilip H. NelsonProtection of juvenile anadromous fish (salmon, steelhead, etc.) duringtheir seaward migration isa major concernin thePacific Northwest.The existingscreening structures at the headend ofpower andirrigation canals have been only moderately successful; therefore,theBureau of Reclamation inconjunction with various local andnationalfishery agencies hasdeveloped animproved screening structure todivert the juveniles back to the river.These facilities are currentlyor will soon be under construction on the Yakima River in thestate ofWashington, and the Umatilla River in the state of Oregon.The existing screeningstructures were placed at rightangles to theflow, hadexcessive velocitythrough thescreens, and utilizedinadequate bypass flows; thereforethey did not provide safe passageof the juvenile fish back to the river.Theimproved design positionsthescreens at askew angle tothe canal centerline to assure anadequate sweeping velocity to move thejuvenile fish to bypassbaysbefore theybecome exhausted andimpinge on the screens,providesadequate screen area forproperapproach velocity, andprovidesincreased bypass capacity toattract thefish to the bypass bays.Close attention was also given to other factors,such as alignment ofthe canal upstream ofthe screens and certain geometric relationships,which are critical to the proper operation of the screens.2. At ThreeMile,louvers were used inlieu of drumscreens and atKittitas, a bar rack on the headworks wasin theory supposed toservesimilar to louvers. The efficiency of thesesystems was extremely low.The current designs weredeveloped cooperatively between the Bureau ofReclamation, the NationalMarine FisheriesService, theWashingtonStateDepartment ofFisheries, theOregonDepartment of FishandWildlife. the Yakima Indian Nation, and the Confederated Tribes of theUmatilla IndianReservation. Thefishery agencies provided the basicfish related criteria while theBureau ofReclamation developed thedesigns based onthese criteria andconducted model studies forverification of assumptions.The basic screening system includes the drum screen structure; a bypasssystem, including ariver return pipe andoutlet structure; and adownstream control structure toassure a properwatersurface at thedrum screenstructure. A trashrackstructure is provided if there areno trashracks on the canalheadworks structure-Also, a pumpbacksystem and/or a juvenileevaluation facility may beincluded in thedesigns, if required. Although the structuresateach screen locationare site specific, the following "generic" or basic set of criteria wasdeveloped.Other features addressed include a trashrackstructure to protect thescreens: a pumpback-bypass structure, if flows in the river between thepoint of diversion and the point of fish bypass returnare critical: ajuvenile evaluation facility, if required; and a river return system tosafely return the fish to the river.TRASBRACK STRUCTUREINTRODUCTIONIf a trashrack structure is required it will be placedupstream of thedrum screen structurenormal to thecanal flow. The width of thetrashracks is based on an approach velocity of 2 ftls (0.m/s).Thebarspacing isbased on thesize of thetrash in the canal. Thetrashracks are placed on a 1:1 slope for ease of manualcleaning. Ifthetrashracks are to becleaned with an automated trash rake, thetrashracks are placed on a1/4:1slope. Ifthetrashracks are to beremoved forwinteroperation, andthere is apotential sedimentproblem, then they are designedto endapproximately one-third thewater depthabove thebottom of thecanal.The trashracks arefabricated in sections to facilitate removal and storage during winteroperation.The existing screening structures, built prior to 1955, placed near theheadworks of theChandler and RozaPower/Irrigation Canals and theKittitas Main Canal on the Yakima River in the stateof Washington andat the ThreeMile FallsDiversion Dam on theUmatilla River in thestate of Oregon haveproveIT to be inadequatefor 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 CenterDRUM SCREEN STRUCTUREEngineering & Research CenterFor thescreening structure to operategiven to the following details:as desired, attention must be532534WATERPOWER 'JUVENILE ANADRAMOUS FISH PROTECTIONDIMENSIONSOFTHE DRUM SCREENSThediameter of thedrum screensshould be set so thatapproximately 70% to 80% ofthe drum screen issubmerged in the water duringnormal operation.Thedrum screensshould never be submerged more than 90% as the very small juvenile fishmay impinge on and be carried over the drum screens.The drum screens are covered with4 by 4mesh,cloth, O,105-inch-diameter wire (3.68 mmcleardiameter wire), witha 33,6% opening.Thisjuvenile fish frompassing throughthescreen.durable enough to withstand winteroperation andwi thoutdamaging the cloth.stainless steel wiopening with 2.67 rom-fabricprevents smallAlso this screen ismay bewalked onIntermediate Bypass Bays and BlanksDrum Screen StructureBecause of thepossibility of winteroperation the drum screensaredesigned foras-foot (1.5 m) head differentialin the event icingoccurs. The gantrycrane is designed toautomatically pull one drumscreen if thedifferential becomestoogreat, Onthese proj ects allthe screens are 12 feet (3,66 m) long regardless of theirdiameter tofacilitate transportation and tokeep possible iceloads at areasonable value,Ct. Chandler Cana IFlowSKEW ANGLE- The drum screen structure shouldbe skewed15 to 17,degrees from the canalcenterline, as shown onFigures 1, 2, and 3.This will provide a sweepingvelocity along theface ofthe drumscreens of about 1,to 1,9 ft/s (0,5 to 0,58 m/s) when the velocitynormal to the drum screens is 0.5 ft/s (0.15 m/s),The sweepingvelocity is essential in movingthejuvenile fish towards the bypasssystem,Access RampJ /:lBypass BayBypass PiPes~ /Gravity Bypass ,/ /from Pump sump7 /if"";!'""oot'" """"I ..---7River Return Pipe/..-/'rrdLIiJ-.=-- ~pumpbackBypassVELOCITYOFAPPROACHThe velocity ofapproach normal to the drumscreens is to be no greater than 0.5 ft/ s (0 .15 m/ s),The area used tocompute this velocityshall be the vertical projected area of the drumscreen, not including the area occupied by the side or bottom seals.GEOMETRY INTO AND OUTOFTHE DRUM SCREEN STRUCTURE- Thegeometry intoand out ofthe drumscreen structure is very important to maintainequal flow through all of thedrum screens. Modelstudies show thatthe following items contribute to this equal flow.30'Y'162030EDIATEINTERMTYPICAL BYPASS"".YA KIMAturn Pipe d)-............../'River Re (Submerge----------OutletSECTION THROUGH TYPICALSUBMERGED OUTLETI. There shouldbe nocurves or abrubt variations in cross section inthe canal for a distance of 20T+ upstream of the drum screen structure,where T isthe widthofthe ~anal prism at thewater surface. Thiswill assure a relatively uniform flow across thecanal prism at thedrum screen structureand,therefore, equal flowthrough the drumscreens. If acurve is tooclose to the drumscreens theremay bereduced or evenreversed flow through the first or second drum screenwhich will result in an increasedflow through other screens on thesystem. Anabrupt changein thecrosssection just upstream of thedrum screens can also cause nonuniform flow through the screens.If itis impract icalto have a straightsection of canal this long in frontof the drum screen structure then some means of producing uniform flowsshould be investigated.A model study is one means of determining anappropriate solution. Anotherpossibility, if a trashrack structure isrequired, is to placestoplogs in a pattern that produces the desiredGENERAL PLAN -CHANDLER(TWENTY- FOUR 13" DIA. 12" LONG DRUM SCREENS)50 050100 150,..,,--'SCALE OF FEETFigure I

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# -.)538JUVENILE ANADRAMOUS FISH PROTECTION539WATERPOWER 'flow.swim against the current infront of adrum screen for longer than 2minutes before a bypass bay is reached.Model studies have shown thatthe angle of the training wallshould be at a slightly different anglethan the skew angle, as shown on Figure 1.Also shown in Figure 1,thereshould be awider pier at thislocation to assure full flowthrough the drum screen just downstream of the training wall,When two or more bypass bays are required, the bypass pipes shall enteranupwell prior toentering the pumpback structure or the juvenileevaluation facility. The volume of theupwell, in ft3. (m3), is 8QH,where Q isthebypass capacity in ft3/s (m3/s) and H is the velocityhead in feet (m) of V2/2g. Tomaintain equal flow through each bypass,individual adjustable weirs arerequired. Thelifting device on theadjustable weirs will have a yokesuch that no stems will be intheflow.Without a model study this becomes a trial and error solution.2. By using a transition or a blank wall, thefirst drum screen couldbe placed approximatelyone screen width downstream of the theoreticalintersection of the water surface on the canal bank and the face of thefirst drumscreen, as shown in Figure2.This will help to achievefull flow through the first drum screen.3. Thechannel sidesupstream anddownstream of thedrum screenstructure mustbe parallel to each otherfor thelength of the drumscreen structure, This will help keep theflow uniform as the watermoves through the screens.INTERMEDIATE PIERSThe piersbetween the drum screens, or theintermediate piers, will take theshape ofthedrum screen on theupstream side, asshown on Figure 3.The piers takethis shape sothere are no obstructions in the path of the juvenile fish asthey areswept along the face of thescreens and past the piernoses, and toeliminate areas for predator fishtooccupy.Stoploggrooves areprovided downstream of the drumscreens to allow for flow control inthe event there isunequal flow through the drumscreens.This isanother way ofproducing theuniform flow desired, but as with thestoplogs at the trashrack structure, becomes a trial and error solutionin the absence of a model study. Also, the stoplog grooves are used toinstall a bulkhead gateincase adrum screen isremoved for anemergency situation,RIVER RETURNPIPEThe interior ofthe river return pipe and alljoints between pipe sections mustbesmooth.The fisheryagenciesprefer PVC pipe with asecond choice being mortar lined steel pipe,The fishery agencies also prefer large radius bends in therange of 10pipe diameters ifbends are required. Theflow in the pipe may be ashigh as 15 ft/ s (4.6 m/ s) but nohydraulic jump will be allowed in thepipe. Ifthere is an excessive head differential between the canal andthe river then there must be intermediatedownwells between the canaland the riverorthere must be an outfall at the river.If downwellsare required, the drop should be no greater than 10 feet (3 m) and thewater depth should be 5 to 6 feet (1.5 to 1.8 m),RIVER RETURN PIPE OUTLET- The twobasic typesof river return pipeoutlets are the submerged pipe outlet and the outfall type outlet,Thesubmerged pipe outlet mustbe set to be submerged for all riverflows,as shown on Figure 1. The outlet area shouldhave a volumesimilar toan upwell and must bearranged such that flow is passing through thisarea at all timesso thejuveniles areswept outminimizing theproblems associated with predatorfish. Itis best to put this typeoutlet in a portion of the river wherethe water ismoving relativelyfast. Ifan outfall isused, as shown on Figure 2, there should be apool ofadequate depthbelow the outfall.The mostimportantconsideration is tospread thewater atthe outfall asmuch aspossible, while maintaining at least a D,foot (0.15 m) flow depth atthe outfall. This will breakup the water entering the plunge pool andminimize the problems associated with the shear zone of ajet enteringquietwater,The distancefrom themaximum operating pool watersurface to the bottom of the drop structure should be aminimum offeet (3 m)soadultsjumping do not hit thebottom of the outlet.Also, the end of the outlet must be far enoughfrom theriverbank sothe adults that jump do not beach themselves.BYl'ASS SYSTEMTHE BYPASS BAY- Thebypass systembegins with the bypass bay at thedownstream end of thelast drumscreen orat theappropriateintermediate drum screen. This bypass bay should be a verticalchannel2 feet (0.6 m) wide that is open to the full water depth.The velocityinto the channelis 2ft/s (0.6 m/s), which is approximately the sameas the sweeping velocity along the drum screens.The capacity of thebypass will be thatrequired to produce the 2 ft/s (0.6 m/s) velocity.A set of vertical slots may be placed at the entrance of the bypass forinstallation of avertical orifice if areduced bypass capacity isrequired. In this waythe 2 ft/s (0,6 m/s) velocity into thebypassmay be maintained with thereduced bypass capacity, When moving fromthe bypass channel into thebypass pipe, thevelocity shouldgradually increased from 2.0 ft/ s (0.6 m/ s) in thechannel to a highervelocity as the water either passes into adownwell or directlyintothe bypass pipe,The purpose of this istomove the fish into thefaster velocitywaterbeforethey realizethe velocities areincreasing, since the juvenilefish tend to avoidsudden changes invelocity by moving back upstream. When goinginto the pipe asquare-to-round or rectangular-to-round transitionshould be used with theleading edges rounded with an approximate 0.5-foot CO.15 m) radius,DOWNSTREAM CONTROLSTRUCTUREIf the canal diversion is large and asizeable number of drum screensare required, thenintermediate bypass bays will berequired. As ageneral rule the bypasses should bespaced such that thetravel timealong the screens isno longer than 2 minutes, so no fish will have toThere should be acontrol downstream of the drum screen structure tomaintain the desired water surface atthe drumscreens asthe flowcapacities in the canal change, It is important thatthe water surfaceat the drum screens remain fairly constant for proper operation of the...:540WATERPOWER '-q:\ '., L-0. 0)..,- ~\ j ,D- 'C'" "L-".,-0::"\ ~L- 00~o ,.....0",0::0::0:: 0...:::I:::Ig w~ 0...J:;: If)If)L- 'CU '"en "E 'C=' "'- ""'.,c: .Q+- 0'" +-(J)f! r/' ,a; ::CY'~ : ~ ~(J)Figure 4JUVENILE ANADRAMOUS FISH PROTECTIONbypass system, Also, if the watersurface getsbelow one-half adrumdiameter, the small trash will not be picked up on the drum screens andthis trash must then move through the bypass system.PUHPBACK SYSTEMCI1lJ.JIl::::;;::JIl:c:::( C)N Z0::: =..JZ -C\Jc:::(-' xa.. '.::(-' 0c:::( =a:: aUJ -I"-l.LI -C) z:;.A pump back system isrequired if theexisting canalsection istoosmall to carry the required canal and bypass capacities or if the riverflow between the point of the diversion and the pointthe river returnoutlet is reduced below that required for adult upstream migration.The pumpback system basicallyconsists of traveling water screens, onthe side of the bypass channel, thatwillbleed off thewater notrequired forreturning the fish tothe river, andpumps locateddownstream of the traveling water screens. Thiswater is thenpumpedinto the canal downstream of the drum screens.Pumpback facilities areshown on Figures I, 3, and4.The approach velocitynormal to thetraveling water screen is 0.5 ftls (0.15 m/s), the same as for the drumscreen. Experiencehas shown that a continuous wire cloth water screenworks better thantraveling waterscreens fabricated with steel framebaskets. This is dueto the requirement of tight seals and no openingsgreater than 1/16 inch (1.6 rom). A gated gravity pipe comes out of thepump sump downstream of the traveling water screen to returnthe waterto the river if the pumps shut down or if this water is not required inthe canal.JUVENILE EVALUATION FACILITYAny juvenile evaluation facility required byfishery agencieswillprobably be a custom designasthe requirements for these facilitiesvary greatly from site to site.If aminimum evaluationfacility isadequate thenaninclined screen, an adjustable weir for water levelcontrol, and a separator for separating trash and adultfish fromthejuvenile fish, is placedin the bypasschannel. Any time a juvenileevaluation system is required it isimportant to maintain a constantoperating water surface at thedrum screens, as this affects the waterlevel control in the juvenile evaluation facility.CONCLUSIONSA basicgeneric model of ascreen structure toprotect juvenileanadromous fish may bedeveloped, but experiencegained during thedesigns of the aforementioned sites hasshown that allfacilities aresomewhat site specific. The work on the Chandler system(Figure 1) theKittitas system (Figure 2) and the Three MileFalls System(Figure 3)are allvariations of thebasic drumscreen system with some sitespecific considerations, but, the work on theRozasystem (Figure 4),with the "saw-tooth" configuration on the drumscreens, is a completesitespecific design thatrequired anindependent model study.Therefore, each site mustbe addressed based on itsown merits and asystem devised to satisfy thespecific siteconditions and all fishrelated criteria.