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north Fork nooksack river In-channel Project
Project overview TheNorthForkNooksackIn-channelprojectwasdevelopedcooperativelybetweentheUSDAForestServiceandtheNooksackSalmonEnhancementAssociation(NSEA),withtheobjectivesof(1)decreasingegg-to-frylossofnativechinook,coho,cutthroat,pink,sockeye,steelhead,andcharduetoreddscourand(2)decreasingfrequencyofdewateringofside-channels,whichareareascontainingvaluablespawningandrearinghabitat.The3-mileprojectreachmarkstheuppermost extent of anadromous use and consistently sees a high amount ofusebyspawningNorthForkNooksackRiversalmon.ThereachisalsousedextensivelyforstockenhancementintheNooksackChinooksalmonrecoveryprogram.TheNorthForkIn-channelProjectwascompletedintwophasesinthesummersof2003and2004.Itconsistsof36logjams(9smallunballastedand27largeballastedstructures)throughthe3-milereach(figure1).TheLummiIndianNation’sNaturalResourcesDepartment(LNR)hasbeenworkingwiththeUSDAForestServicetomonitorthehabitateffectsoftheproject,whileNSEAhascompletedtopographicsurveysthroughthereachtohelpcharacterizethegeomorphicresponse of the channel to the structures.
Weexpectthatdifferentiatingtheriverresponsetotheprojectfromthenaturalrangeofconditionswilltakelong-termmonitoring.Thisreportrepresentsonlythefirstyearofpost-constructionmonitoring.Theprojectreliesonthedynamicthatexistsbetweenriparianforest,woodrecruitment,andwoodjamsintheNorthForkNooksack.Thisprojectisthefirststageinrestoringaself-sustainingdynamicrivermorphologyandhabitattoaforestedfloodplainriver.Thefollowingmonitoringresultsonlyaddressthefirststageof“riverdevelopmentsuccession,”hasteningwoodcollectionandbardevelopment.Oncethebarsbecomemorestable,vegetationcolonizationofbarscanbegin.Establishedvegetationisexpectedwithin3years,includingeffectivevegetationfilteringoffloatingwoodduringfloodevents.Finally,continuedvegetationandwoodcollectionwillleadtoperiodicalchannelblockageandresultantshiftingintooverflowchannelswithaprojected25-percentincreaseinreconnectedfloodplainchannels.
Eachofthesedevelopmentstakestime.Thissystemaveragesa4-yearadjustmentperiodfrommajorstormsduetolimitedstabilizingelementslikelargewoodypieces.Sixmajorevents(greaterthan10-yearreturninterval)haveoccurredsince1989,andstormsofthissizearethetriggerforthelargersedimentpulsesandwoodrecruitment(USDAForestService1995).SincethestormofrecordfortheNorthForkNooksackoccurredin2003,weprojectthatitwillbe2007whenthetellingresultsandconclusionscanbemade.Weexpectthatthesechangesinhabitat-
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formingprocesseswillleadtoreducedscourofreddsandmorestableside-channelhabitat.Abasin-widereportonreddscourintheNooksackBasinfoundreddscourtobegreatestinmain-stemandbraidedreaches,anditsuggestedusingwoodtostabilizebarsandincreasesidechannelhabitatasameansofreducingreddscourandlimitingthedewateringofsidechannels(HyattandRabang2003).
Project Methods, design, and Monitoring Thebasicdesignformonitoringtheresultsofthismultiyearstructure-
placementprojectwastocomparefishhabitatchangesbetweenthepre-andpost-projectconditions.First,weusedafive-levelhierarchicalhabitatclassificationsystem(basedonmodificationsofthehabitatclassificationsystemdescribedbyHawkinsetal.1993)todescribehabitatinthereach.Thefirst-levelclassificationidentifiedthechanneltypesasmainchannel,braidedchannel,orsidechannel,whilelevels2through4classifythemaingeomorphicunits(pools,riffles)ofthechannel.Forlevel2,thewaterisclassifiedasfastorslowmoving.Level3furtherseparatesthesetwoclassesasturbulentornonturbulentfastwater,andscourpoolordammedpool.Level4dividesthesegroupsfurther.Forexample,turbulentrifflescanbeclassifiedasfalls,cascades,rapids,riffle,orchute;andscourpoolscanbeclassifiedaseddy,lateral,midchannel,trench,convergence,orplunge.Weclassifiedbankconditionsbyresistancetochannelmigration,eitherbedrock,boulder,orarmored.Ifthebanksfellinnoneofthosecategories,weclassifiedthembytheriparianstandcharacteristics(DuckCreekAssociates2000).
Second,foreachhabitatwemeasuredunit,length,width,maximumandaveragedepth,bankangle,vegetationoverhang,undercutbanks,lengthandwidthofavailablecover,anddominant/subdominantsubstrateweremeasured.Wemeasureddepthwithastadiarodandrecordedittothenearest0.1meter.Tocharacterizethebankangle,wemeasuredthedistancefromthetoeofthebedtothewateredge(measuredhorizontallyalongthewatersurface)andthedepthofthewateratthetoe.Forexample,aperfectlyflat(horizontal)bankwouldbe0degreesandaverticalbankwouldbe90degrees.Undercutbankswouldhavebankanglevaluesofgreaterthan90degrees.Wemeasuredvegetationoverhangwithastadiarodandincludedonlyvegetationwithin300millimeters(1foot)ofthewatersurface.Weestimatedeachcovercomponentbasedonlengthandaveragewidth,or(inthecaseofsubstrate)asapercentageoftheentirehabitatunit.
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Figure 1. General location of the North Fork Nooksack in-stream project.
Third,wemappedlargewoodydebrisaslogjamsandkey-sizedpieces.Sincethebankfullwidthofthechannelwasgreaterthan20meters(65feet),wedefinedakey-sizedpieceasgreaterthan9cubicmeters(11.7cubicyards)involume(WashingtonForestPracticesBoard[WFPB]1997).Inthisassessment,the“key-sized”designationdoesnotindicatethesizeforasinglepieceofwoodtobestableinthechannel.Instead,itrepresentsthesizeofwoodbeingcontributedbytheapproximately500-year-oldriparianstandsthatexistintwolocationsinthereach.Forwoodaccumulations,welocatedeachlogjamanddescribedanygeomorphicorhabitateffects.Thegeomorphicandhabitateffectsincludedthefollowing:
lsplitlowflow:Thelogjamwasactivelysplittingflowaroundorthroughitduringlow-flowconditions.
lsplitbankfullflow:Thelogjamwouldbesplittingflowwhenthestagewasapproachingbankfull.
lchanneldeflection:Thelogjamwasactivelyturningordeflectingthechannelatlowflow.
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lsedimentstorage:Theevidenceshowedthatthechannelslowedvelocityanddepositedsedimentadjacenttothelogjam.
lpoolformation:Theevidenceshowedscouradjacenttothestructure.
lcover:Thelogjamwasprovidinghidingcoverforjuvenilesduringlow-flowconditions.
Weestimatedthestabilityofthelogjamfromindicatorssuchaspersistentvegetation,effectsonthechannel,andpersistenceofthestructureonaerialphotos.Weindependentlyidentifiedanddescribedanykey-sizedpiecesassociatedwiththelogjams.Themainlimitationofthemappingwasthatsmallerpiecesofdriftwerenotcharacterized.Therefore,wecouldnotcharacterizethetotalvolumeofwoodinthereach.
Monitoring results and Interpretation Project Reach Changes Althoughthereachhasanaverageslopeof0.008,thisslopevaries
considerablywithinthereachfrom0.005to0.02(Indrebo1998;GeoEngineers,Inc.2001).Theactivechannelwidthvariesfromapproximately50feet,whereitisconfinedbetweenbedrockwalls,tomorethan650feet,whereitisoftenbraidedorhasvegetatedislandssplittingthechannel.Thechannelisdominatedbyriffle-poolmorphology,withsubstrate,vegetation,andwoodydebrisformingthedominantroughnesselements,dependingonthedegreeofchannelconfinement.Weestimatedthebankfulland2-yearreturnintervalsforthedischargeinthereachat4,400cubicfeetpersecondforthebankfullintervaland6,000cubicfeetpersecondforthe2-yearreturn(Indrebo1998,GeoEngineers,Inc.2001).Sinceconstruction,theprojecthasbeensubjectedtoseveralflowsgreaterthanbankfullstage,whichoccurredinmid-October2003.AlthoughaU.S.DepartmentoftheInteriorU.S.GeologicSurveygaugeatroadmarker63andwithintheprojectreachwasnotreporting,theflowwasestimatedtohavebeenapproximately14,000cubicfeetpersecond,withasecondarypeak5dayslaterofover12,000cubicfeetpersecond(GaryKetcheson,U.S.ForestService,personalcommunication,May2004).Thesewerethelargestfloodssincethegaugebeganoperationin1937,andbothofthesepeakswereestimatedtohavebeengreaterthanthe100-yearfloodlevel.Thefloodappearstohavehadonlyamodestimpactonthechannelplanform,largelyintheunconfinedsectionsoftheprojectreach.Intheseareas,meanderbendshavemigratedslightlydownvalley,orsedimentdepositionhasledtobraidingofthechannel.Inothersectionsofthereach,thechannelappearstohaveincisedandnarrowedduringtheflood.
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Fish Habitat-forming Processes—Sediment Production and Transport Intheprojectreach,sedimentissuppliedfromtributarieswithinthe
reachandasbedloadtransportedfromupstream.Acomparisonofaerialphotos,conductedbyGeoEngineers,Inc.(2001),indicatestheoccurrenceoffrequentfluctuationsinchannelwidth—episodesofacceleratedlateralmigration,bankerosionandchannelavulsion(theremovalofapieceofland from one property onto another as a result of a shift in the course of aboundarystream).TheNorthForkWatershedAnalysis(USDAForestService1995)foundarelationshipbetweenchannelwideningandfloodoccurrenceintheresponse(lowergradientandunconfined)reachesoftheNorthForkNooksack.
Evidenceofpastperiodsofaggradationandincisionarepresentinthenumerousterraceswithinthemoreconfinedportionsofthereach,alongwithin-situstumps(exposedinthechannel)thatrepresentaforestthatwasburiedinsedimentandisnowbeingexhumedbythechannel.Somecharredstumpsareattributedtothevastforestfiresthatburnedintheregion(R.Nichols,USDAForestService,personalcommunication,May2002).Severallargeprehistoricfireshavebeendocumentednearthereachincludinglargefiresin1300,1500,and1700(USDAForestService1995).Inonecase,nearly15feetdifferentiatethecharredstumpsintheactivechannelandtheyoungerstumpsonanadjacentterrace.Whenviewedincontextwithoneanother,theseobservationssuggestthattheobservedchannelinstabilityisaresultofepisodicsedimentdepositionandchannelaggradation,followedbyerosion,incision,andchannelmigration(GeoEngineers,Inc.2001).
Theestimatedstreampower(theslope-dischargeproduct)forthisreachisroughly1/4thatoftheupstreamreach,indicatinganabruptreductionintransportcapacity(GeoEngineers,Inc.2001).Therefore,largesedimentpulsesgeneratedfromtributariesupstreamaretransportedintosectionsoftheprojectreachanddeposited,wheretheyaretemporarilystoredastheymoveslowlythroughthereach.Thesesectionsaregenerallytheunconfinedareaswherethechannelisfreetorespondtothesedimentbyaggradation,channelmigration,andbraiding.Intheseareas,thechannelisgenerallybetterconnectedtothefloodplainthanarethemoreconfinedreaches,andwooderodedfromthebanksremainsmorestableinsidechannelsandongravelbars.Intheseresponseareas,thehabitatismostdiverseandthegravelmostsuitableforspawning.Habitatmappingshowedsecondarychanneldevelopmentoccurringprimarilyintheseareas.Whilethesecondarychannelsappearedtobemoreephemeral,thegravel-dominatedsubstrateintheseareaswasmuchmoresuitableforspawningthanmainchannelhabitatunits(figure2).
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Figure 2: Substrate difference between secondary and main-stem channel types in 2004.
Sincetheprimaryobjectiveoftheprojectwastodecreaseegg-to-frylossofnativesalmonidspeciesduetomainchannelscouranddewateringofsidechannels,theprojectwilllikelyneedtochangelocalscouranddeposition through the reach in places that maintain multiple channels. Increasingtheflowresistanceinthereachbyaddingstableaccumulationsofwoodcanslowthewatervelocity,leadtosedimentdeposition,andcauselocalscourwherethestructureconstrictstheflow.Theincreaseinwood(associatedwiththeproject)inthemoreconfinedreacheshaslikelyincreasedflowresistancefortheseareas,andinmanycases,localeffectsoftheengineeredlogjamsonthechannelwereevident.Weidentifiedlocalsedimentstorageassociatedwiththeman-madestructuresfor16ofthe26logjams,and,localscourfor13ofthe26logjams.Butweidentifiedonly26oftheoriginal36structuresafterthefloodevent.Incaseswheremultiple-engineeredstructureswerecoveredinaccumulateddebrisordepositedtogether,weidentifiedandmappedthemasonestructure.
Fish Habitat-forming Processes—Channel Migration and Wood Recruitment
Bankconditionsnaturallyinhibitwoodrecruitmentinsectionsofthereach.Insectionswherethebankscompriselargeboulderdepositsorbedrock,channelmigrationisslowedorhaltedandthemodeof
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recruitmentisdominatedbyslopefailureandwind-throw,ratherthanbychannelprocesses.Thisleavesapproximately64percentofthechannellengthasareasinwhichrecruitmentfromchannelmigrationprocessescanoccur(table1).Intheseareas,weclassifiedtherecruitmentpotentialaccordingtostandtype,size,anddensity(DuckCreekAssociates2000).Wedefinedhighwoodrecruitmentpotentialasstandsthatweredense(lessthan1/3exposedground)andeitherconifer-dominatedormixed,withtreesgreaterthan12inchesindiameter(WashingtonStateForestPracticesBoard1997).Sincethe“high”designationrequiresonlya12-inch-diametertree,thesestandsdonotnecessarilyreflectthesizeneededforstablelargewoodydebris.Onlyabout1/3ofthe“highrecruitment”length(about3,280feet)comprisesstandsthatgeneratethesizeofwoodmappedinthechannel.Fromthisclassification,wedesignated34percentoftheriparianlengthas“low”or“moderate.”Thisdesignationislargelytheresultoffloodsandpasttimberpracticeswheretheriparianareaswereharvested.Withprotectionoftheriparianareas,weexpectthatthestandsshouldreach“high”statusfairlyrapidly—dependingonsiteconditions.Thistimelagmaybeimportant,becausetheriverwillrelyonthelimitedamountofcurrent“high”recruitmentareauntiltheregeneratingareasfullyrecover.Oncetheseareasrecover,themorestablein-channelwoodshouldrapidlyincreaseinthewidersectionsofthevalley.Themoreconfinedsectionswilllikelycontinuetobedominatedbywoodtransportand temporary storage.
Table 1: Bank condition and wood recruitment potential of the project reach.
Banks Length (feet) Percent
Armored 2,950 9
Bedrock 4,310 13
NaturalBoulder 4,720 14
HighRecruitment 10,100 30
ModerateRecruitment 3,720 11
LowRecruitment 7,500 23
Beforeconstruction,key-sizedpiecedistributionandhabitatcreationinthereachappearedtostronglyreflectbankconditions.Thehighestdensityoflargepieceswasinanunconfinedsectionofthereachimmediatelyadjacenttoasourceoflargediametertrees.Thecombinationoflarge-diameterriparianforest,unconfinedchannel,andunarmoredbanksmakethissectionanaturalplaceforlargewoodtohavealongerresidencetimeintheactivechannelandprovideimportanthabitatfunctions,suchas
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complexcoverandpool-formation.Inaddition,becausethisreachisalessconfinedandlowerenergyreach,secondarychannelscandevelopandsubstrateisbettersuitedtospawningthaninthehigher-energysections.Inthemoreconfinedsectionsofthereach,poolformationisdominatedbyboulderbanksandbedrock,whileintheunconfinedreach,poolformationwasdominatedbywood.Evenundertheseconditions,muchofthelargewoodwastransporteddownstreamduringtheOctoberflood,somepiecesasfaras4,000feet(R.Nichols,USDAForestService,personalcommunication).Followingconstruction,thisunconfinedsectionofthereachstillhadthehighestdensityofkey-sizedpieces.However,sectionsmoreconfinedandsectionsthatlackedrecruitmentpotentialsawanincreaseinkey-sizedpieces,becauseofstructuressitedinthosesections.
Channelmigrationandwoodrecruitmentthroughthereachislargelyunimpededbyhumaninfluences.TheMountBakerHighwayliesontheboundaryofthemigrationzoneonthenorthside,andaUSDAForestServiceroadliesonthesouthernboundaryofthemigrationzone(GeoEngineers,Inc.2001).Bothoftheseroadshavearmoredsectionswheretheriverhasmigratedtotheroad.Theselocationshaveonlyaminoreffectonhabitatformationandprovidelittlebenefitforin-streamhabitat.Oneofthesevenmainchannelpoolsmappedin2004wasattributedtobankprotection.However,inthiscase,itwasaseriesoflogscabledtogetherbetweenrockdeflectorstoprotecttheUSDAForestServiceroad.Becausemuchoftheprojectreachhasnaturalbankscomprisedoflargeboulders,therockbankprotectionprojectsareconsistentwithnaturalbankconditionsbutlackthestreamsidevegetationthatcharacterizethenaturalboulderbanks.
Fish Habitat-forming Processes—Large Woody Debris Largewoodydebrisprovidesimportantfunctionstothechannelthrough
sectionsoftheprojectreach.Thepreprojectdistributionofinstreamwoodstronglyreflectedthechannelbankfullwidthandentrenchment,aswellastheproximitytorecruitmentareas.Formuchofitslength,theprojectreachhasnorecruitmentfrombankerosion,becauseofbedrockoutcrop,boulderlagdeposits,orbankprotection.About37percentoftheleftbankand46percentoftherightbankdonotactivelycontributewoodtothechannel,exceptthroughwind-throworlandslides.Beforetheproject,thewoodintheactivechannelareawaslargelylocatedimmediatelyadjacenttorecruitmentareasintheunconfinedreaches.Oncethewoodistransportedfromtheunconfinedareastothemoreconfinedareas,itislikelytoberapidlymoveddownstreamtothenextunconfinedarea,whereit has a longer residence time.
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InFebruary2002andMarch2004,wemappedkey-sizedpiecesofwoodthroughouttheprojectreach.Weidentifiedkey-sizedpiecesasthosegreaterthan9cubicmeters(11.7cubicyards)involume(WFPB1997).Beforeconstruction,woodsizeappearedtohavelesstodowithstabilityandfunctionthanthechannelcharacteristicsandthepositionofthewoodinthechannel.Stablepiecesrangedinsizefrom2feetto6.1feetindiameter,asizesimilartounstablepieces(2feetto5.2feetindiameter).Ofthepiecesidentifiedasstable,nearlyallwerelocatedinthebraidedreachesoftheriver.Inaddition,ofthose38piecesweidentifiedashavingapool-formingfunction,only6occurredinasinglethreadmain-stemchannel.Allotherswerefunctioninginbraidedchannelsorsidechannels.Thisobservationfurthersuggeststhatthewoodisbeingmovedmorequicklythroughtheconfinedareasanddepositedintheunconfinedreaches,whereitfunctionstoprovidehabitat.Oncethewoodisdepositedintheunconfinedareas,itmayfurthercontributetocreatingbarsandsplittingtheactivechannelintoabraidedoranastomosingsystem.
Afterconstruction,thedistributionofkey-sizedpiecesinsectionsoftheprojectareachanged.Theprojectwhichfocusedonincreasingtheresidencetimeofthewooddriftintherivertreatedthemoreconfinedportionsoftheprojectreach.Thefurthestdownstreamsectionsawadramaticincreaseintheamountofkey-sizedpiecesafterconstruction.Abouthalfthekey-sizedpiecesidentifiedinthereachin2004wererelatedtotheproject.Theriverdepositedtheotherhalf.Asidefromthisincreaseintheamountofkey-sizedpiecesinthefurthestdownstreamsection,theunconfinedareasstillcontainedthehighestwooddensity.
Beforeconstruction,twogeneraltypesofaccumulationsoccurredinthereach:Logjamsformedviastabilizeddriftmovingthroughthesystem,andlogjamsformedin-situwheretheriverhasmigratedintoaforestedterraceorfloodplain.Thissecondgroupoflogjamstendedtoformintheunconfinedreaches,whereterracesandawiderfloodplainexist.Inareaswithnolocalsourceforrecruitment,onlylogjamsformedbydepositionandstabilizationofdriftoccur.
Logjamsprovideavarietyoffunctionstothechannelinthereach,includingchanneldeflection,channelaggradation,poolformation,coverforfish,andbankprotection.Ingeneral,thein-situlogjamsprovidedbankstabilityanddeflectedflowawayfromthebanks—inseveralcasesmeteringflowintosidechannelsbehindthelogjams.Insomereaches,wherestumpsarebeingexhumedinthechannel,thedrift-formedlogjamsareoftenformedbymobilewoodrackinguponthestumps.Theselogjams
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arestableatlowflows,butasthestageincreases,woodbuoyancytendstoliftthedriftoffthestumpsandallowittocontinuedownstream.Oneaccumulationwasassociatedwithabankprotectionproject,wherelargelogsarecabledintothechannel.ThisprojecthasbeensuccessfulincausingsomeaggradationalongthebankandisprovidingprotectionfortheUSDAForestServiceroadwhileprovidingcoverforfish.
Afterconstruction,thenumberoflogjamsintheprojectreachincreasedsubstantially.Ofthe42logjamsinthereachaftertheflood,26wereengineeredstructures.Fiveofthe27largeengineeredstructuresmovedorcameapartintheflood,andwemappedtheseas“engineered”iftheywerestillcabledtogetherandfunctioningasaunit.Theyseremappedas“natural”iftheyhadcomeapartandwerefunctioningmoreasanaturallogjam.MostofthemanmadeandnaturallogjamsthatsurvivedtheOctoberfloodappearedtobestable,with88percentofthenaturallogjamsand96percentoftheengineeredlogjamsshowingstability.
Thebigdifferencebetweentheman-madeandnaturallogjamswasinthelocalgeomorphicandhabitatvaluesassociatedwiththestructure.Thesevaluesdependonthestageoftheriver(table2).Evidently,thenaturallogjamshadamuchgreaterimpactonhabitatfunctionthantheconstructedlogjams,aneffectthatcouldberelatedtothedifferentchannel position of the man-made and natural logjams. Most of the natural logjamswereatthesameelevationastheactivechannel,whilemanyoftheengineeredstructuresweresitedhighonterracesadjacenttotheactivechannel,withtheintentofcapturingdriftduringfloodstage.Manyofthosestructuresthatwereintheactivechannelareainconfinedreachesoftheriverweremoveddownstreamtomoreunconfinedreaches.Ifthesestructurescameapartduringtransport,thenweclassifiedthemasnaturallogjamsandattributedtheirhabitatvaluestonaturalaccumulations.
Table 2: Comparison of habitat functions provided by natural and man-made logjams in the project reach.
Type(count) Percentage of Logjams Providing Function
Split Low Split Channel Sediment Pool Cover Flow Bankfull Deflection Storage Formation
Natural(16) 25 56 38 63 63 75
Manmade(26) 4 46 0 62 50 62
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Fish Habitat—Habitat Distribution and Character Geologyprovidesastrongcontrolonhabitatformationintheproject
reach.Inareaswherethevalleybottomiswide,thechannelisabletomigrateandavulseacrossthefloodplain,recruitingwoodasitmovesandcreatingmultiplechannelsthatincreasethediversityoffishhabitatinthereach.Inthesereaches,localaccumulationsofwoodappearveryimportantforgravelsortingandscour.Inmoreconfinedreaches,thechannelrespondsthroughchannelaggradationandincision,formingandmaintaininghabitatthroughinteractionoftheriverwiththebedrockorlargebouldersthatcomprisethevalleywalls.
Wechosethelow-flowperiodforhabitatmapping,becausetheseconditionsshouldrepresenttheminimumaccessiblehabitatareaforthereach.Thedischargein2002was233,288,289,and540cubicfeetpersecondduring4daysofmapping,whilein2004thedischargewas362,438,409,and431cubicfeetpersecond,whichwasrepresentativeoftheaveragemonthlydischargeforthatperiod(474cubicfeetpersecondinFebruaryand408cubicfeetpersecondinMarch).FollowingtheOctoberflood,thereachsawanetincreaseinhabitatareaduringthelow-flowperiod(table3).Thisincreaseinmainchannelareareflectsanincreaseinlengthfrom30,960feetto36,670feetandanaverageincreaseinwidthfrom78feetto94feet.Themainchannelareaincreasedbymorethan300,000squarefeet,whileeachofthesecondarychanneltypesshowedadecreaseinarea,inspiteofhigherdischargeduringthe2004mappingperiod than in the 2002 mapping period. The secondary channel location alsochangedasexistingchannelswereabandonedandreoccupiedfollowingtheflood.Inonecase,down-valleymigrationofameandercouplethasevidentlyopened1,400feetofsidechannelonthenorthsideofthevalley,whileabandoning2,600feetofsidechannelonthesouthsideofthevalley.
Table 3: Area of channel types from 2002 and 2004.
Year Channel Type ( in square feet)
Main channel Side channel Braided channel Total Area
2002 732,670 222,135 621,680 1,576,490
2004 1,046,530 159,060 584,950 1,790,530
Habitatmappingintheunconfinedreachalsoshowedachangeinthedistributionofhabitatclassesbetweenthetwoyears.Theamountofareaclassifiedas“rapid”increasedmarkedly,whiletheamountofareaclassifiedas“riffle”decreased.Poolandrunareastayednearlyconstantbetweenthetwoyears.Poolscharacteristicsweremeasuredduringthe
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winterlow-flowperiodoftheNorthForkNooksackinFebruary2002andMarch2004.In2002,wemappedonlysixchannel-spanningpoolsintheprojectreach,comprising7.5percentofthemain-stemhabitatarea(table4)andyieldingapool-to-riffleratioof1:12.3forthereach.Fiveofthepoolswereformedbyscouralongbedrockoutcrops,andonewasformedbywoodydebris—aseriesofin-situstumps.Complexwoodycoverforholdingadultsorjuvenilerearingdominatednoneofthelargepools.Channelspanningpoolswerespacedevery33channelwidths(basedona95-footaveragechannelwidth).Inallcases,thelargepoolswerelocatedfarfromthebraidedareaswherethemostsuitableandstablespawningsubstrateislocated.
Habitatmappingin2004showedareductioninpoolhabitatfollowingtheOctoberflood.Whilesevenofthemainchannelunitswerepools,theycomprisedonly4.3percentofthemain-stemhabitatarea(table5).Thisyieldsapool-to-riffleratioof1:17.4forthereach.Abigchangeoccurredinthepool-formingfeaturesinthereach:Whilein2002bedrockdominatedpoolformation(table4),in2004poolformationwasdominatedbywood(table5).Themeanresidualpooldepthdecreasedslightly,from5.2feetto5.0feet,from2002to2004.Whilethechangeindominantpool-formingfeaturefrombedrocktowoodmayimplythatthepoolhabitatislessstablethanitwas,thechangealsoshowsanimprovementincoverquality(table6).Cover,particularlyfromhighwatervelocity,canbecriticalforrearingjuvenileandholdingadultsalmon.
Table 4: 2002 main channel pool statistics (LNR2002).
Unit Forming Area Residual Number Feature (square feet) Depth (feet)
13 Bedrock 14,625 6.9
14 Bedrock 13,452 5.1
21 Bedrock 20,124 7.8
26 Bedrock 23,760 5.4
32 Wood 9,720 2.2
35 Bedrock 29,280 3.8
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Table 5: 2004 main channel pool statistics (LNR 2004)
Unit Forming Area Residual Number Feature (square feet) Depth (feet)
20 Wood 6,327 5.2
53 Wood 18,225 3.3
72 Wood 13,671 2.7
73 Wood 10,080 3.6
75 Wood 5,832 6.7
80 Bedrock 9,072 6.6
82 Bedrock 14,337 6.6
Thepresenceoffewlargepoolslikelydemonstratestheimportanceofsmallholdingareasandpocketpoolsinthereachforsalmonbeforespawning.Althoughgenerallysmall,pocketpoolswereprevalentthroughthereachandwerecreatedbyeitherwoodydebrisorlargeboulders.Thepocketpoolscreatedbywoodaccumulationofferedcomplexcoverand,astheywereoftenlocatedinbraidedreaches,offerednearbygravelforspawning.Pocketpoolscreatedbybouldersweregenerallylocatedinthehigherenergysectionsofthereach,wherelocalscourresultedinlittlegravelsorting.
Another change is the increase in pools in secondary channel areas. In 2002,noneofthebraidedsectionsshowedsignificantpooldevelopment,whilein2004fivepoolswereformedinbraidedsectionsoftheriver.Inthelowestdownstreamsectionoftheprojectreach,wherewehaddoneextensivewoodplacement,thebraidedportionofthechannelnowhasthreepools—twoformedbyengineeredlogjams(figure3).Ofthefivepoolsformedinsecondarychannels,largenaturallogjamsontheoutsideofmeanderbendsformedtwo,localscouradjacenttoanengineeredstructureformedtwo,andbedrockformedthelast.
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Figure 3: New pool development in braided section of the project reach following construction.
Fish Habitat—Cover Wecharacterizedcoverforallhabitatunitsintheprojectreachin2002
andin2004.Formainchannelpools,thedominantcovercharacteristicschangedbetween2002and2004,reflectingthechangeinpool-formingfeature(table6).Dominantcovertypeisdefinedasthemostabundantcoverpresent.Inmostcases,theunitshavemultiplecovertypesofvaryingcomplexity.Thechangetowoodasadominantcovertypeshouldimprovetheuseofthepoolsbyrearingjuvenilesandholdingadults,bothofwhichshowastrongpreferenceforwoodcover.Coverforjuvenilerearingthroughoutthereachismostlyprovidedbythesubstrate,eithernonembeddedcobblesorboulders.Woodydebrisformedalargerportionofthecoverintheside-channelandbraidedareaswherethewoodtendedtoaccumulateandremainmorestable.
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Table 6: Dominant cover type in main channel pool units 2002 and 2004.
Year Dominant Cover Type
Bedrock Substrate Wood Riprap
2002 1 4 0 0
2004 1 3 3 0
Fish Habitat—Substrate Composition Ingeneral,cobblerifflesdominatethemainchannelthroughthe
reach,eveninthelowergradient,lessconfinedsections.Thecobble-dominatedreachesofthereachchangedincharacterfollowingthelargefloodinOctober2004,whenthesubdominantclasssizewentfrombeingpredominantlybouldertopredominantlygravel(table7).Beforeconstruction,28percentofthemainandbraidedchannelarea(orabout409,680squarefeet)wasdominatedbygravel-sizedmaterialatlowflow(about250cubicfeetpersecond).Afterconstruction,littlechangeoccurredinthegravel-dominatedarea,with25percent(orabout402,040squarefeet)ofthetotalmainandbraidedchannelarea.Althoughwedidnotcharacterizesubstrateforthesidechannelareas,itwasgenerallyfinerthanthatinthemainchannel,andgravelrepresentedalargerproportionofit.Localsortingeffectsresultingfromwood,boulders,andinteractionwithstreambanksandbarsyieldedpatchesofspawninggravelthroughoutthereach,although,forthemoreconfinedareas,theseweregenerallysmall and appeared ephemeral.
Table 7: Substrate in habitat units (2002 and 2004).
Substrate Percentage of Total Main and Braided Channel (Dominant/ Subdominant) 2002 2004
Cobble/Boulder 39 11
Cobble/Gravel 33 64
Cobble/Sand 0 <1
Gravel/Boulder 2 <1
Gravel/Cobble 20 18
Gravel/Sand 6 6
Sand/Cobble 0 <1
TotalArea 1,450,505ft2 1,659,061ft2
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Project Monitoring Partnerships and Costs PartnersinthismultiyearmonitoringeffortincludestheLummiIndian
Nation,NooksackTribeofIndians,NooksackSalmonEnhancementAssociation,WhatcomCounty’sUSDANaturalResourceDistrict,WhatcomCountyConservationDistrict,U.S.DepartmentoftheInteriorNationalParkService,andWashingtonDepartmentofTransportation.Table8showsthecostsforthismonitoring.
Table 8. Costs for monitoring.
Task(s) Organization Costs by Year ($)
Habitatandwood LummiIndianNation 15,000in2002mapping 10,000in2004
OrthoPhotoandCross NooksackTribe 7,800in2002 section/scour of Indians monitoring
Crosssections; NooksackSalmon 10,000in2002 GPSstationing EnhancementAssociation 5,000in2004
Aerialmappingand WhatcomCounty’s 1,500in2003 GISproducts; NaturalResource 4,000in2004 surveyingtraverse. ConservationDistrict
Aerialmappingand WhatcomCounty 1,500in2002 GISproducts ConservationDistrict 1,500in2003
PhotoPoint NationalParkService, 1,000in2002 NorthCascades 1,000in2003 NationalPark 3,000in2004
GPSStationing WashingtonDepartment 1,500in2004 of Transportation
Reports USDAForestService 4,000in2004 MtBaker-Snoqualmie NationalForest
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Lessons Learned Sincetheprojectwasconstructed,theprojectreachhasundergoneseveralchangesthathaveimplicationsforhabitatquality.Muchofthechangethatoccurredinthereachwasrelatedtotwofloodsinmid-October,bothofwhichweregreaterthanthepreviousfloodofrecord.Changesthatweobservedanddocumentedare:
lChangesindominantpool-formingfeaturefrombedrocktowoodinmain channel reaches.
lIncreaseinpoolsinbraidedchannelareas.
lIncreaseinwoodasadominantcovertypeinpools.
lIncreaseinrapids,decreaseinriffles.
lChangeindominantsubstrateclassinmainandbraidedchanneltypesfromcobble/bouldertocobble/gravel.
l Local effects of engineered logjams on channel including sediment deposition and scour.
lIncreaseinkey-sizedpiecesinconfinedportionsofthereach.
lIncreaseinnumberoflogjamsthroughthereach.
lReductioninsecondarychanneltypes(braidedandsidechannels),increase in main channel area.
Many of these changes directly relate to the engineered logjams constructedasapartoftheNorthForkNooksackIn-channelproject,whileothersaremoredifficulttoattributetorestorationactivities.
For more information contact: RogerNichols,MtBakerRangerDistrict,MtBakerSnoqualmieNational
Forest,2105Highway20,SedroWoolley,WA98284;phone:360-856-5235.
references Cited DuckCreekAssociates.2000.NooksackRiverWatershedRiparianFunction Assessment.
Geoengineers.2001.NorthForkNooksackRiverCorridorAnalysis.(UnpublishedreportpreparedfortheWashingtonStateDepartmentofTransportation).56p.
Hawkins,C.P.;Kershner,J.L.;Bisson,P.et.al.1993.Ahierarchicalapproachtoclassifyingstreamhabitatfeatures.Fisheries18:3-12.
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Indrebo,M.1998.StreamchannelclassificationandhistoricalchannelchangesalongtheNorthForkNooksackRiver,Washington.PreparedforLummiNaturalResources,Bellingham,WA.47p.
LummiNaturalResources.2002.Habitatmappingandwoodcharacterizationdataforthefour-mileflatsreach.GISdata.
LummiNaturalResources.2004.HabitatmappingandwoodcharacterizationoftheNorthForkNooksackIn-channelprojectreach.GISdata.
Ketcheson,G.2004.CommentsregardingthepeakdischargesexperiencedinthenationalforestattheU.S.GeologicalSurveygaugelocatedattheNooksackPowerhouseduringthetwoOctober2003floodsevents;personal communication.
Nichols,R.2002.Commentsregardingthefirehistorythatburnedintheregionoverthepast500years;personalcommunication.
U.S.DepartmentofAgriculture,ForestService.1995.Pilotwatershedanalysisforcanyoncreek.SedroWoolley,WA:U.S.DepartmentofAgriculture,ForestService,MtBaker-SnoqualmieForest,MountBakerRangerDistrict.276p.
U.S.DepartmentofAgriculture,ForestService.1995.Northforknooksackriverwatershedanalysis.SedroWoolley,WA:U.S.DepartmentofAgriculture,ForestService,MtBaker-SnoqualmieForest,MountBakerRanger District.
WashingtonForestPracticesBoard.1997.Standardmethodologyforconductingwatershedanalyses.Version4.0.
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