case study 8 north fork nooksack river in-channel project plan/lores/ch3_cas… · case study 8...

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Case Study 8

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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developing Monitoring Plans— Chapter 3

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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Case Study

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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