’s Aquatic Environments: Hiram M. Chittenden Locks

Hiram M. Chittenden Locks The following write-up relies heavily on the Hiram M. Chittenden Locks/ Bay Subarea Chapter by Fred Goetz in the Draft Reconnaissance Assessment – Habitat Factors that Contribute to the Decline of Salmonids by the Greater Lake Technical Committee (2001).

Overview The Hiram M. Chittenden Locks (Locks) were Operation of the navigational locks involves constructed by the U.S. Army Corps of Engineers raising or lowering the water level within either (the Corps) in 1916 and commissioned in 1917. the large or small chamber so that vessels may The Locks were built as a navigation project to pass between the two waterbodies. The filling and allow boats to travel from the marine waters of emptying of the large lock chamber is achieved by to the protected freshwaters of Lake use of a system of two large conduits that can Union and . The Locks are either fill the entire lock or half of the lock. This comprised of two navigational lock chambers: a is achieved by using a miter gate that divides the large lock that accommodates both large and small large lock chamber into two sections. Water is vessels and a small lock used by smaller vessels. In taken into the conduits via two intakes addition to the lock chambers, the Locks include a located immediately upstream of the structure. , 6 bays, and a fish ladder. Water is conveyed through each conduit and is The Locks form a dam at the outlet of the Lake discharged into the lock chamber through outlet Washington and /Ship system on each side of the chamber. The Locks that maintains a higher water level in the Ship include a series of six spillway bays to pass excess freshwater inflow over the dam until the level of Canal than in tidally-influenced . the Ship Canal drops to 20 feet MLLW. This most The level of the water upstream of the Locks is commonly occurs in June. maintained between 20 and 22 feet above mean low low water (MLLW) during most years. Since the original construction in 1916, the Locks have been upgraded several times to improve both upstream passage for adults and downstream passage for outmigrating smolts. The improve- ments include the reconstruction of the fish ladder in 1976 to facilitate upstream migration of adults. A program to install up to four smolts began in 1995 and was completed in 2000. The smolt flumes provide improved passage for outmigrating juveniles and have significantly improved smolt passage through the structure when water is available for their use.

Historical Modifications

Physical Changes The Locks serve as a dam between the freshwater environment of Lake Washington and the marine environment of Shilshole Bay (Puget Sound). Construction of the Locks and the Lake Washing- ton Ship Canal resulted in substantial physical modifications to . Historically, Salmon Bay was a long, shallow, tidally-influenced, saltwa- The Hiram Chittenden Locks — looking westward. ter embayment of Puget Sound (Weitkamp et al. 2000). As part of the construction of the Lake

45 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks the inlet,saltwater isconveyedbacktoward Puget near theupstreamendof Locks.Afterentering drain withaninletatthebottom oftheShipCanal The saltwaterreturnsystem consistsofasaltwater dense saltwaterfromflowing towardLakeUnion. forebay oftheLocksandpartially blocksthemore Ship Canal.Thebarrierisconstructedacrossthe reduce theamountofsaltwaterintrusioninto A saltwaterbarrierandareturnsystem denser saltwatertointrudeupstreamoftheLocks. the operationoflargelockchamber,allows The operationofthelockchambers,particularly water intrusiontotheShipCanalandLakeUnion. operating theLocksishowtolimitupstreamsalt One oftheprimarychallengesindesigningand brackish-water . the Lockshasremainedatidally-influenced, freshwater .SalmonBaydownstreamof Locks, SalmonBaywasconvertedintoadeep ment. Throughdredgingandconstructionofthe estuarine environmenttoafreshwaterenviron- creation ofanabrupttransitionfromatidal, The constructionoftheLocksresultedin Limnological Changes MLLW (Weitkamp Lake Washingtonis21.0feet(+/-onefoot) Union/Lake WashingtonShipCanalsystemand Waterway. ThemeanelevationfortheLake Union andraisedthelevelofSalmonBay between 8to10feettheexistinglevelofLake effectively loweredthelevelofLakeWashington The constructionoftheLocksandShipCanal et al. Salmon Bayasaresultofthisdredging(Weitkamp nearshore andwetlandhabitatswerelostin oftheLocks.Approximately1,300acres upstream oftheLocksandSalmonBaydown- and channelizedintotheSalmonBayWaterway Washington ShipCanal,SalmonBaywasdredged structure. Waterway bothupstreamanddownstreamofthe the LocksandarmoringofSalmonBay extensive shorelinehardeningalongbothsidesof Other habitatmodificationsattheLocksinclude approximately 70percentofthetime. maintain anelevationofatleast20feetMLLW ington issuchthatsufficientwatercanbestoredto feet MLLW.TheavailablestorageinLakeWash- ton haveoccasionallydroppedtoaslow18.5 water levelsintheShipCanalandLakeWashing- managed between20and22feetMLLW,although 2000). et al. 2000)withelevations 46 In 1976,thefish ladderwasrehabilitated toattract migration ofsalmonthrough theLockscomplex. The goalofthefishladder is tofacilitateefficient large lock,thesmalland thesaltwaterdrain. salmon canpasstheLocks via thefishladder, via oneoffourpossibleroutes.AdultChinook ton basinmustnegotiatepassagethroughtheLocks upstream spawninggroundsintheLakeWashing- Adult Chinooksalmonmigratingfromoceanto Adult Migration juveniles passingthroughthefacility. and haveincreasedthesuccessofbothadults have servedtoreducetheeffectofthisblockage ments thathavebeenimplementedattheLocks niles; however,thevariousfishpassageimprove- barrier bothtoadultfishandoutmigratingjuve- . Historically,theLockshasbeenapartial outmigrating smoltsandasadultsreturningto drainage mustpassthroughtheLockstwice,as All ChinooksalmonintheLakeWashington Chittenden Locks Chinook UtilizationoftheHiramM. the watercolumn(Simenstad warmer freshwatersislimitedtotheupperareasof salt watersoccurringalongthebottomwhile become stronglystratified,withthedenser,cooler Canal immediatelyupstreamoftheLocksto (Corps,1999).ThiscausestheShip wedge intrudesintoLakeUnionanduptothe limit saltwaterintrusion.Whenthisoccurs,a low, thesaltwaterdrainmaynotbesufficientto traffic isheavyandwaterlevelsareattheirseasonal however, duringthesummerperiodwhenboat drain reducetheimpactofsaltwaterintrusion; flow season.Thesaltwaterbarrierand about 67percentofallwaterusedduringthelow flowing throughthesaltwaterdrainrepresents amount offreshwater.Duringthesummer,water Operation ofthesaltwaterdrainrequiresalarge present configuration. for thereconstructionoffishladdertoits of sufficientattractionflowswasaprimaryreason reconstruction ofthefishladderin1976.Thelack feature wasaddedtothesaltwaterdrainduring ladder toprovideadditionalattractionflows.This below theLocksandpartofitflowingtofish the flowwithpartofitproceedingoutdirectly east ofthedamstructure.Herea“Y”jointsplits Sound throughaconcreteconduittopointjust et al. 1999). Seattle’s Aquatic Environments: Hiram M. Chittenden Locks more fish and to ease upstream migration. Prior to June. Migration continues through early July. rehabilitation, migration delay and passage prob- The combination of lake-rearing juveniles and lems at the Locks may have reduced the annual delayed migration are hypothesized to be the cause runs of by up to 20 percent of the unusually large Chinook smolts produced (WDF, 1971). Since rehabilitation in 1976 approxi- from the Lake Washington basin. Larger size may mately 80 percent of all adult Chinook salmon use be beneficial as a result of increased ocean survival the ladder (Muckleshoot and WDFW, unpublished rates; however, more study is necessary on this data) and about 20 percent of all adult Chinook issue. salmon use the large lock. Smolts may remain in the Locks for days to weeks. Average residence times of fish at the Locks vary Larger smolts, such as steelhead or , depending on their success ascending the fish may move through the Locks in hours or days. ladder. In 1999, fish that successfully negotiated Smaller smolts, in particular Chinook salmon, may the fish ladder on the first attempt had an average remain in the Locks for weeks at a time, feeding residence time of 15 days at the Locks. Fish that and attaining size prior to entering Puget Sound. were unsuccessful in negotiating the fish ladder the Large numbers (thousands) of juvenile Chinook first time averaged 23.5 days residence time at the may remain in the large lock chamber, feeding, for Locks. Time of day and tidal stage are known to several days. Tagged juvenile Chinook have been affect upstream movement of Chinook through the known to pass through the smolt passage flumes, fish ladder. These same factors influence fish then return to the Ship Canal through either the movement in natural . small or large locks, and be passed a second time through the flumes (R2 Resource Consultants, Juvenile Migration 2000). Juvenile Chinook enter Lake Washington over an extended period from January through at least mid- Habitat Requirements July (WDFW, unpublished data) with two peaks of migration from . A large down- Fish Access and Passage Barriers stream movement of Chinook fry occurs immedi- (a) Adult Fish Passage ately after emergence in February and early March when small fry leave upper areas and enter An important issue related to the Locks is the the lake. A second smaller peak occurs during extent to which upstream migration of adult May and June when larger juveniles migrate Chinook is delayed as a result of the facility. downstream to the lake as part of their migration Migration delay may lead to increased energy to saltwater. expenditure, stress, susceptibility to disease, and Seasonal outmigration timing for juvenile Chinook altered spawning timing. The new fish ladder salmon at the Locks appears unique in comparison constructed in 1976 was designed to reduce migra- to juvenile Chinook outmitgration timing for tion delay and facilitate upstream migration based other Puget Sound Chinook stocks. Saltwater on the best available information at that time migration through the Locks appears to occur later (Corps, 2000). In addition to the new fish ladder, in the Lake Washington system. While the Corps has implemented some additional outmigration in other Puget Sound can improvements including reconstructing the begin as early as March or April (Myers et al. entrance to the fish ladder and enhancing the flow 1998), no juvenile Chinook have been captured in of water to facilitate the ability of adult fish to find March or April at the Locks and rarely have the ladder. juvenile Chinook been found in early May. Based A small number of adult fish may also pass up- on a variety of data, about 5 percent of the Chi- stream through the saltwater drain, but recent nook juveniles pass the Locks in May, over 50 improvements in drain operation procedures are percent pass the Locks in June and about 40 believed to minimize the use of this route. Fish percent pass in July. Most of the earlier migrating attraction to the drain has been reduced by closing juvenile Chinook are of hatchery origin. the drain during the summer when tides can exceed Wild fish first begin appearing in catches in early 7 feet and by operating the drain primarily at night June with the peak outmigration period for wild when fewer adults migrate. In addition, adult Chinook juveniles occurring during mid to late Chinook may enter the intake of the saltwater 47 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks upstream ofthe project.Fishenteringthe ladder oxygen levelsofanyareafor asignificantdistance has thecoolesttemperatures andhighestdissolved intrusion ofsaltwaterfrom PugetSound,thisarea periods (average19-20days). Becauseofthe the Locksheldnearsaltwater drainforlong ers notedthattheChinookpassedupstreamof channel upstreamofthesaltwaterdrain.Research- immediately movetothedeepestpartof after migratingthroughthefishladder,adult Studies oftaggedadultChinookhaveshownthat conditions. for Chinooktofindmorepreferablehabitat Locks, thereislessvariabilityandopportunity tures, salinity,andcurrentvelocities.Atthe down thechannelselectingpreferabletempera- natural estuarywouldbefreetomoveupand into theShipCanal.Incontrast,Chinookina Locks, butcurrentsarenegligibleoncetheypass Chinook encounterwatercurrentsbelowthe warmer, lesssalinewaterabovetheLocks.Also, more salinemarinewaterbelowtheLocksto Chinook encounteranabruptchangefromcooler, and moreenvironmental.AttheLocks,adult issue relatedtopassageappearsbelessstructural Sincethereconstructionofladder,primary with saltwaterinthedrain. seasonal lowandlessfreshwaterisavailabletomix ter outflowsfromLakeWashingtonareata summer (JulythroughSeptember)whenfreshwa- salinity ismosttypicallyaconcernduringthe discourage fishfromusingtheladder.High salmonid speciesindicatethathighsalinitymay not beenconducted,investigationsonother salinity onChinookmigrationintheladderhave high tide).Althoughstudiesoftheeffects of thefishladder,andbytidestage(highsalinityat fresh waterfromabovetheLockstolowerhalf saltwater drain,whichtransportsamixofsaltand in theladderisinfluencedbyoperationof an importantfunctionofthefishladder.Salinity freshwater flowsasacueforhomingChinookis attraction offishtotheladder.Maintaining been identifiedasapotentialfactoraffecting Salinity intheentrypooltofishladderhas (BioSonics, 2000;HTI,2000). tracking themovementsofadultsinforebay hydroacoustics andvideocamerasaswellby adult Chinookiscurrentlybeinginvestigatedwith the six-footdiameterpipe.Useofdrainby entering thedrainshouldbeabletoswimoutof drain ontheupstreamsideofLocks.Salmon 48 of juvenilesalmon migratingthroughthe Locks. provements havebeenused toimprovethesurvival and evaluationcoupledwith smoltpassageim- 1999; Maule ability (Schreck,1996;Maule andVanderkooi, 1964; Schreck,1982,1992), anddiseaseresistance for saltwaterentry(i.e.,smoltification;McInerney, ance (Mesa,1994;Schreck quality ofoutmigrantsintermspredatoravoid- and Smith,1976).Injurystresscanreducethe of smoltscanincreasedelayedmortality(Bouck survival. Forexample,injury(descaling,bruising) (smoltification) havebeenshowntoinfluence relating tofishhealthanddevelopment migrate throughtheLocks.Anumberoffactors In mostyearsmorethan2.5millionsmoltswill Seiler, WDFW,unpublisheddata). outmigrating juvenileChinook(Corps,1999; lack offacilitiestoimprovesurvivalfor smolt-to-adult survivalprimarilyasaresultofthis cantly affectyear-to-yeardifferencesinsalmon operation oftheLockshaspotentialtosignifi- wire-tag datahasindicatedthatthedesignand Locks andtheavailabilityofmorerecentcoded- juveniles (smolts).Ongoingmonitoringatthe pass downstreammigratingsalmonandsteelhead rehabilitation laterincludedspecificfeaturesto Neither theoriginalconstructionofLocksnor (b) JuvenileFishPassage may benormalbehaviorforfallChinook. 1964). Sosomeoftheapparentmigrationdelay Verhoeven andDavidoff,1962;Vernon estuaries foraboutonemonth(Wendler,1959; indicatethatfallChinooknormallyholdin (Fresh near-surface temperaturesdropbelow22degreesC temperature withfishholdingattheLocksuntil in 1998,isthatresidencetimeafunctionofwater section. Theinitialtheory,basedonobservations This isdiscussedfurtherinthewaterquality Canal inthesummer,appeartoplayamajorrole. particularly lowdissolvedoxygenlevelsintheShip upstream ofthefacility.Waterqualitylimitations, on migrationdelaysonceChinookhavemoved It isdifficulttodeterminewhatroletheLockshave Canal inlessthanoneday. leave theLocks,mostfishmovethroughShip tagged fishattheLockswas52days.Oncethey 1998 and2000,thelongestresidencetimeforany summer hadtheshortestresidencetimes.Between residence timeswhilefishmigratinglaterinthe in lateJulyandearlyAugusthadthelongest et al. 1999).However,studiesinother et al. 1989).Since1994,monitoring et al. 1997);preparedness et al. Seattle’s Aquatic Environments: Hiram M. Chittenden Locks

Fish passage improvements were completed in passage within a wider range of available flows. 2000 with full implementation expected by 2001 or The primary concern with the smolt passage 2002 through structural and operation changes. flumes is the potential lack of available water to There are a combination of 12 different routes allow operation of the flumes during the later part outmigrating Chinook smolts may use to pass of June and July when most juvenile Chinook through at the Locks. These include fish moving salmon are migrating through, or rearing below, through the fish ladder, over the spillway, through the Locks. When water isn’t available, Chinook the saltwater drain, or through the lock chambers and other smolts are forced to select other routes and/or the culvert systems for both the small lock to exit the Locks. By this time in the migration and the large lock chambers. Although 12 routes season, juveniles are likely highly motivated to are possible, data collected over the past four years migrate from physiological cues or due to the indicates that Chinook smolts are most likely to increasingly high temperatures in the Ship Canal. pass through one of three major routes: 1) over the spillway (via the smolt passage flumes or under the Spillway gates are typically mentioned as the spillway gates), 2) through the large lock gates, or preferred means to pass juvenile salmonids through 3) through the filling culverts for the large lock. water control structures (Williams et al. 1996). Both the fish ladder and saltwater drain appear to There are still periods in late when addi- pass small numbers of migrating juvenile salmon. tional water must be spilled under the spillway However, use of the saltwater drain may be higher gates at the Locks to maintain the maximum pool during drought years when there is limited water elevation. Water may also be spilled through the available after early June to operate the smolt spillway gates to provide additional adult fish passage flumes or spillways. It is likely that few attraction during the late winter and spring adult fish use the small locks. steelhead migration. The minimum opening for the Locks spillway gates is 0.5-foot and they are Smolt Passage Flumes and Spillway Gates currently operated at this level. At other water control projects () in the Pacific Northwest, By late spring, the flow volume into the Ship Canal the minimum gate opening recommended for is usually reduced such that the spillway gates passing juvenile salmon is 1.0 foot (Williams et al. cannot be opened wide enough most days to safely 1996). The difference between how the gates are pass smolts. Further, late spring and early summer operated at the Locks and at other projects does inflow (May-July) to the Ship Canal appears to not appear to be a concern for fish survival. have been reduced since the late 1970s as a result of natural climate variability (Houck, 2000) and increased water demand within the basin (Horner and May, 1998). Prior to 1995, little or no water was spilled over the dam during most days in June and July. In 1995, a prototype low- flow smolt bypass was installed that used only 20-25 percent the water volume necessary to open a spillway gate 1.0 foot. In 2000, the prototype flume was replaced with the four smolt passage flumes capable of passing nearly the equivalent amount of water as would pass through a 1.0 foot spillway gate opening. Installation of these four flumes has allowed the Corps to increase their opera- tional flexibility and to use water more efficiently for safe smolt Recently installed smolt flumes assist juvenile passage past the locks.

49 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks in 2000there was a75percentreduction insignifi- encrusted barnaclesandother debris.Asaresult, bare concreteusingahigh-pressure washtoremove and outofthelargelockchamber werecleanedto November of1999,allthe conduitsleadinginto deposited intheupperhalf ofthelockchamber.In smolts stillentrainedintotheculvertintakesand large lockswastoreducetheinjuryrateofany A secondobjectiveoftheimprovementsto from 1996to2000. average 83%reductionintheentrainmentrate average entrainmentwas93fishperfilloran 2000 wasreducedto45-120fishperfill.The of themigrationseason)entrainmentratein addition of4newflumes(3operatingmost were withoneflume(80cfs)inplace.Withthe smolts perlockageevent.Theseentrainmentrates lockage event.In1998,itwasbetween211to360 1996, anaverageof540smoltswereentrainedper attracted andentrainedintotheculvertinlets.In lessened thelikelihoodofjuvenilefishbeing and culvertinlets.Reducedflowrateshave decreased watervelocitiesinthefillingconduits during eachlockcycle.Lowerfillrateshave tions inthefillrateoflargelockchamber operation ofthesmoltpassageflumesandreduc- is mainlyduetotwofactors:installationand dramatically reducedbetween1996and2000.This smolts intothelargelockfillingculvertshasbeen that areentrained.Asaresult,entrainmentof juvenile fishandtolowertherateofinjury and 2001includedactionstoreduceentrainmentof Smolt passageimprovementscompletedin2000 the pipingthatcouldinjurefish. obstructions suchasbarnaclesorsharpbendsin this processifwatervelocitiesarehighorthere because juvenilefishcanbeinjuredorkilledduring pipes attheLocks.Entrainmentisimportant through thefillingconduits,culverts,ordrain juvenile salmonswiminto,andthenareswept lence” andisusedtorefertheprocessinwhich “phenomenon ofbeingcarriedalongbyturbu- conduit system.Entrainmentisatermforthe injured ordisorientedsmoltspassedthroughthe through theconduitsystem;and2)predationof subsequent injuryandmortalityduringpassage ment intothefillingconduitsandculverts juvenile salmonuseofthelargelockare:1)entrain- through theLocks.Themainconcernsregarding source ofinjuryandmortalityforsmoltspassed The largelockshasbeenimplicatedastheprimary Large Locks 50 Water Quality during thislife historystagehasunknown effects this highgradientareamay becomestressed.Stress anadromous fishmigrate.Fish passingthrough systems andarenotfound in mostareaswere occur attheLocksareuncommon innatural Ship Canal.Severetemperature gradientsthat temperature conditionsattheLocksandin salmon migrationoccursduringthemostsevere may delayadultmigration.TheChinook indicate thathightemperaturesintheShipCanal mortality ofadultChinooksalmon.Severalstudies creation ofathermalwaterbarrier,anddirect temperatures mayleadtoincreasedpredationrates, ation attheLocksrelatedtoChinook.Higher Temperature isaprimarywaterqualityconsider- saltwater intrusionisstillknowntooccur. saltwater draindiscussedabove.However,some including installationofthesaltwaterbarrierand to reducesaltwaterintrusionabovetheLocks, Several modificationshavebeenmadetotheLocks have deleteriouseffectsonbenthicorganisms. through LakeUnion.Theanoxicconditionsmay oxygen upstreamoftheLocksand,attimes,up stratification canleadtolowlevelsofdissolved to theMontlakeCut.Saltwaterintrusionand water wedgeintrudesintoLakeUnionandevenup water enteringthefreshwatersystem,andasalt drain cannotkeepupwiththeamountofsalt period ofheavyboatingactivity,thesaltwater present acrosstheLocks.Duringsummer is constrainedandasignificantsalinitygradient The saltwater–freshwatermixingareaattheLocks lower chamberisuncertain. lead toagreaterreductionininjuryratesforthe upper chamber.Whetherbarnacleremovalcould is slightlyhigherinthelowerchamberthan upper lockchamber(10-15%).Barnacleregrowth to 3timesgreater(35%)thanthosereportedinthe Pre-baseline injuryvaluesinthelowerlockareup depositing juvenilesalmoninthelowerchamber). ment duringadownlocking(bothresultin full lockingbutwehavenomeasureofentrain- lock. Weknowmorefishareentrainedduringa during a“downlock”orfillingofthefull are depositedinthelowerlockchambereither gap regardingfishinjuredafterentrainmentthat in theupperchamberissubstantial,thereadata While thereductionininjuryrateforfishcaptured lock chamber. cant injuryratestofishentrainedintothelarge Seattle’s Aquatic Environments: Hiram M. Chittenden Locks on Chinook behavior and survival. Increased known avian and mammalian predators on Chi- water temperatures in the Ship Canal in June and nook salmon are gulls, harbor seals, and California July may adversely affect the migration route sea lions. Gull predation on juvenile Chinook in selected by smolts at the Locks with smolts select- the lock chamber has virtually been eliminated ing deeper depths as temperatures since implementation of the slow fill procedures in increase beyond their temperature threshold. This 1999. may result in increased levels of entrainment The numbers of harbor seals and California sea through the saltwater drain or large locks conduit lions in Puget Sound have increased significantly in system. recent decades. Between 1985 and 1995, significant Juvenile salmon (smolts) normally require a period numbers of adult steelhead were consumed by sea of time to acclimate to marine waters. At the lions. In 1996, NMFS authorized removal of Locks, smolts are directly passed into the marine several nuisance sea lions and subsequent predation waters of Puget Sound. High temperatures are also rates on steelhead declined. Concurrent with removal of the nuisance animals, NMFS has been known to affect the ability of smolts to transition running an acoustic deterrent device (ADD) or to and grow in a saline environment. Potentially, a acoustic harassment device (AHD) immediately significant problem at the Locks is that as a result downstream of the Locks. The ADD acts as a of high temperatures smolts are forced into the behavioral barrier to sea lions, emitting sounds in a marine system before they are physiologically frequency range that appears to exclude most ready, and that may cause mortality in the estuary. animals from the Locks area (Fox et al. 1996). Sea The artificial estuary below the Locks is lacking lions have not been observed preying on salmonids most of the functions of a natural estuary. The near the Locks since 1999. Harbor seals are numerous water outlets at the Locks diffuse the present in Puget Sound year-round and are more flows through the small estuary below the Locks, abundant than sea lions. They commonly attack and little or no freshwater lens is formed during salmon, but predation by harbor seals at the Locks the late spring and summer low flow season. This has been infrequently observed. The numbers of freshwater lens is common in natural estuaries and juvenile Chinook taken by harbor seals is believed provides a variety of salinity levels within the to be a small percentage of the run. for Chinook to use during outmigration. Studies from other estuarine areas Below the Locks, in west Salmon Bay and Shilshole Bay, a pilot study was conducted in support the concept that some juvenile Chinook spring and summer of 2000 to investigate the level salmon life history types are dependent on low of juvenile Chinook salmon predation by marine salinity conditions for a period of time prior to and anadromous fish (Footen 2000). The most movement to marine waters. abundant predators in this area were sea-run cutthroat trout, staghorn sculpin, resident Chi- Predation nook or blackmouth, and native char (presumably Predation on salmon is often greatest at constric- bull trout). Although present, these predators do tions where fish aggregate. The major source of not appear to consume large numbers of smolts mortality from predation on juvenile Chinook (relative to predation rates in the Ship Canal by salmon may come during migration through the smallmouth and largemouth bass). Initial estimates Ship Canal and Lake Union system. Few if any do not suggest that fish predation below the Locks freshwater fish predators such as bass or northern is a significant source of mortality. pike minnows have been captured within the immediate vicinity of the Locks. The primary

51 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks factors forChinooksurvivalandfitnessthroughtheLocks. Based ontheanalysisabove,followingtablesummarizesourunderstandingofmostsignificant ouainCharacteristic/ Population and freshwaterenvironmentsemergeaskeyfocusareas. Chinook pasttheLocksandtoreduceeffectsofabrupttransitionbetweenmarine Among thesefactors,continuedeffortstoincreasethesafepassageofbothjuvenileandadult Constraints Outmigration Juvenile Processes Condition Migration Upstream Requirements Adult Function Passage Successful Passage Successful upstream. warmer freshwater downstream and cool saltwater Physical barrierwith upstream. warmer freshwater downstream and cool saltwater Physical barrierwith Preliminary Focus Areas 52 passage. successful smolt locks toincrease Improvements at downstream oflocks. Salmon Bay smolt flumes)into (particularly through Freshwater input flow. fish ladderwater Saltwater mixedinto Salmon Bay. Freshwater inputinto freshwater environments. barrier betweensaltand Presence oflocksasa filling culverts. entrainment intoLocks Continued smolt outmigration period. Chinook smolt smolt flumesduringpeak freshwater tooperate Limited quantityof freshwater environments. a barrierbetweensaltand ladder. Presenceoflocksas attraction waterinfish oxygen levels.Adequate Canal andlowdissolved temperatures inShip Warm surfacewater Seattle’s Aquatic Environments: Hiram M. Chittenden Locks

Fish Passage Improvement Projects at the Locks Habitat improvement projects should focus on improving those habitat qualities that the science indicates will likely provide the greatest benefit for fish. Habitat restoration projects will be monitored whenever possible. Monitoring will track those critical variables that will help the City to assess effectiveness in meeting project objectives. The City will seek to design and monitor habitat restoration projects that create benefits for multiple species, where this practical and where doing so does not undermine the main objectives of the project. The following table notes projects which have already been completed and projects which might be considered and notes the benefits for fish which each project may create.

Project Name Project Cost or estimate Habitat Requirement Status of Project Project Description Successful Passage Transition

Barnacle removal Annual scraping of sharp-edged Minimize barnacles from the filling culverts’ injury and mortality to $63,000 annually interior walls juveniles entrained into the culverts Underway

Motors to control Installation of new variable speed Allow slower filling filling rate motors on the large filling culverts rates

Underway

Smolt Slides Installation of smolt slides Pass juvenile salmonids over the dam $725,000

Completed

Strobe Lights Installation of underwater strobe Frighten juvenile lights salmonids away from $399,000 the entrances of the filling culverts Installation completed

53 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks .Furtherinvestigatewaystoimprovethe 4. Investigatewaystoincreasetheamountof 3. Determinationofthebestusageavailable 2. Continueevaluationofimplementedimprove- 1. Key researchandassessmentissuesinclude: be quicklyaffectedbyshort-termactions. exists formeasuringhowsurvivalChinookcan been implemented,animmediateopportunity significant numberofimprovementshavealready tions duringthepastsevenyears.Becausea Locks systembyvariousagenciesandorganiza- because therehavebeensomanystudiesonthe survival andfitness.Thissystemisalsounique passage improvementstoincreasesalmonid tant tomonitortheeffectsofnewandongoing natural systemhasbeenaltered.Itwillbeimpor- This systemisuniqueinthedegreetowhich Biological Indicators Addressing Uncertainties .Evaluateadultuseofthesaltwaterdraininto d. Evaluatesalinitylevelsinthefishladderfor c. EvaluatefreshwaterinputintoSalmonBay b. Evaluatesalinitylevelsupstreamofthe a. and juvenilepassage. saltwater/freshwater interfaceforbothadult and July. freshwater availableforfishpassageinlateJune June. little availablewaterforspillaftermidtolate maximum smoltpassage.Inmostyearsthereis freshwater throughtheLockstoprovide 2001. 1996, 1997,1998,2000,andwilloccuragainin Locks. Monitoringandevaluationoccurredin ments relatedtosmoltpassagethroughthe the Locks upstream migration downstream oftheLocks Locks 54 Hicks, M.2000.Evaluatingstandardsforprotect- Greater LakeWashingtonTechnicalCommittee. Fresh, K..L,E.Warner,R.Tabor,andD.Houck. Fox, W.W.,B.Delong,P.Dygert,S.Foley, Footen, B.2000.Preliminaryresultsofaninvesti- Bouck, G.R.andS.D.Smith.1979.Mortalityof BioSonics, Inc.2000.Acousticandvideomeasure- Literature Cited 176 pp. mary. WashingtonDepartment ofEcology. Draft discussionpaperand literature sum- water qualitystandardstemperaturecriteria. ing aquaticlifeinWashington’ssurface Watershed ResourceInventoryArea8. of salmonids.GreaterLakeWashington habitat factorsthatcontributetothedecline 2001. Draft-reconnaissanceassessment– October 1999. ultrasonic telemetry.DraftProgressReport, watershed in1998asdeterminedwith salmon spawningintheLakeWashington 1999. MigratorybehaviorofadultChinook Washington. (Supplement). NOAA,NMFS,Seattle, Ballard Lockstoprotectwintersteelhead lethal removalofCaliforniasealionsatthe Environmental assessmentonconditionsfor Gearin, S.Jeffries,andJ.Scordino.1996. ington. Muckleshoot IndianTribe,Auburn,Wash- in theGreaterLakeWashingtonWatershed. presented attheworkshopChinookSalmon King County,Washington.Preliminarydata salmonids inSalmonandShilsholeBays, (Oncorhynchus tshawytscha)andother predation onjuvenileChinook gation intotheimpactsofpiscivorous Society108:67-69. saltwater. TransactionsoftheAmerican salmon (Oncorhynchuskisutch)infreshand experimentally descaledsmoltsofcoho Study. Ecosystem RestorationGeneralInvestigation Engineers, SeattleDistrict,LakeWashington Report PreparedforU.S.ArmyCorpsof salt waterdrainandspillbay#2.DraftFinal Chittenden Locks:Ayear2000focusonthe ments offishpassageattheHiramM. Seattle’s Aquatic Environments: Hiram M. Chittenden Locks

Hydroacoustic Technology Inc (HTI). 2000. Using Schindler, D. 2000. Predation and temperature. acoustic tags for monitoring adult Chinook Preliminary data presented at the workshop salmon behavior at the Hiram. M. Chinook salmon in the Greater Lake Chittenden Locks. Draft report prepared for Washington Watershed. University of the Seattle District, US Army Corps of Washington, Seattle, Washington. Engineers, for the Lake Washington Investi- Schreck, C.B. 1982. Stress and rearing of salmo- gation Studies. Seattle, Washington. nids. Aquaculture 28: 241-249. Maule, A.G., and S.P. VanderKooi. 1999. Stress- Schreck, C.B., L.E. Davis, and C. Seals. 1996. induced immune-endocrine interaction. Evaluation of procedures for collection, Pages 205-245 in P.H.M. Balm, editor. Stress bypass, and transportation of outmigrating physiology in animals. CRC Press LLC, salmonids, Objective 1: Migratory behavior Boca Raton, Florida. and survival of yearling spring Chinook Maule, A.G., R.A. Tripp, S.L. Kaattari, and C.B. salmon in the lower estu- Schreck. 1989. Stress alters immune function ary. Draft Annual Report 1996, Project and disease resistance in Chinook salmon MPE-96-10. U.S. Army Corps of Engineers, (Oncorhynchus tshawytscha). Journal of Walla Walla District, Walla Walla, Washing- Endocrinology 12)135-142. ton. Mesa, M.G. 1994. Effects of multiple acute stres- Schreck, C.B., L.E. Davis, and C. Seals. 1997. sors on the predator avoidance ability and Evaluation of migration and survival of physiology of juvenile Chinook salmon. juvenile salmonids following transportation. Transactions of the American Fisheries Draft Annual Report 1997, Project MPE-95- Society 123:786-703. 3. U.S. Army Corps of Engineers, Walla Myers, J.M., R.G. Kope, G.J. Bryant, D. Teel, L.J. Walla District, Walla Walla, Washington. Lierheimer, T.C. Wainwright, W.S. Grand, Simenstad, C.S., J. Cordell, and R. Thom. 1999. F.W. Waknitz, K. Neely, S.T. Lindley, and Preliminary Lake Washington Ship Canal- R.S. Waples. 1998. Status review of Chinook Shilshole Bay juvenile salmon habitat salmon from Washington, Idaho, , assessment. Draft Letter Report Prepared for and California. U.S. Dept. Commerce., King County Metro. NOAA Tech. Memo. NMFS-NWFSC-35, Tabor, R, F. Mejia, D. Low, B. Footen, and L. 443 p. Park. 2000. Predation of juvenile salmon by NMFS/WDW. 1989. Environmental assessment on littoral fishes in the Lake Washington-Lake controlling California sea lion predation on Union Ship Canal. Paper presented at the wild steelhead in the Lake Washington Ship Lake Washington Chinook Salmon Work- Canal. National Marine Fisheries Service and shop, November, 2000. Washington State Department of Wildlife, U.S. Army Corps of Engineers Seattle District. Seattle, Washington. 2000. White paper on fish passage at the R2 Resource Consultants. 1998. Annotated bibliog- Lake Washington Ship Canal. Draft report. raphy of literature regarding mechanical U.S. Army Corps of Engineers, Seattle injury with emphasis on effects from spill- District. ways and stilling basins. Final Report U.S. Army Corps of Engineers. 1999. Lake Wash- prepared for U.S. Army Corps of Engineers, ington Ship Canal Smolt Passage Section Portland District. 1135 Restoration Project. Draft Report. R2 Resource Consultants. 2000. PIT tagging of Seattle, Washington. juvenile salmon smolts in the Lake Washing- Verhoeven, L.A., and E.B. Davidoff. 1962. Marine ton basin: year 2000 pilot study results. Draft tagging of Fraser River sockeye salmon. Int. Final Report Prepared for U.S. Army Corps Pac. Salmon Fish. Comm. Bull. 13. 132 p. of Engineers, Seattle District, Lake Washing- ton Ecosystem Restoration General Investi- gation Study.

55 Seattle’s Aquatic Environments: Hiram M. Chittenden Locks Williams, R.N.,L.D.Calvin,C.C.Coutant,M.W. Wendler, H.O.1958.Migrationandfishing Weitkamp, D.,G.Ruggerone,L.Sacha,J.Howell, Vernon, E.H.,A.S.Hourston,andG.A.Holland. Planning Council.Portland,OR.584pp. Scientific GrouptotheNorthwestPower .ReportbytheIndependent tion ofsalmonidfishesintheColumbia Frissell. 1996.Returntotheriver:restora- R.R. Whitney,D.L.Bottom,andC.A. McConnaha, P.R.Mundy,J.A.Stanford, Erho, J.A.Lichatowich,W.J.Liss,W.E. of Fisheries,FishRes.Pap.2:71-81. Chinook salmonin1955.WashingtonDept. mortality ratesofColumbiaRiverspring 224 p. Associates fortheCityofSeattle,June2000. Resources Consultants,andCedarRiver Prepared byParametrixInc.,Natural Chinook populations,backgroundreport. and B.Bachen.2000.Factorsaffecting Salmon Fish.Comm.Bull.15.296p. River conventionareain1959.Int.Pac. salmon runsinandadjacenttotheFraser 1964. Themigrationandexploitationofpink 56