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"ALASKAPOWERAUTHORITYSUSITNAHYDROELECTRICPROJECTTASK3 -HYDROLOGYSUBTASK3.10-INTERIMREPORTLOWERSUSITNASTUD!ES;PRELIMINARYOPENWATERCALCULATIONSAPRIL1981Preparedfor:ACRESAMERICANINCORPORATED,.5 TABLEOFCONTENTSLISTOFTABLES.iiLISTOF-FIGURESiii1INTRODUCTION..........12 -SUMMARY.. . . • • . . . . . . .43 -ANALYSISATSUNSHINESTATION74 -SYNTHESIZEDCROSSSECTIONATDELTAISLANDS125 -ANALYSISATSUSITNASTATION.. . . .216-LOWERSUSITNABASINCHARACTERISTICS26REFERENCES28APPENDIXALOWERRIVERSTUDIES,FLOWREGIMEPREANDPOSTPROJECTMEANMONTHLYSTAGEANDDISCHARGE-i -29 LISTOFTABLESNumber2.14.16.1TitlePreliminaryEstimatesofPreandPostProjectDischargeandStageFrequencyAnalysis.HydraulicParametersISynthesizedCrossSectionIDeltaIslands. . . . . . . . . .LowerSusitnaRiverBasinCharacteristics-ii-61727 LISTOFFIGURESNumber1.13.13.23.33.44.14.24.34.45.15.25.35.4TitleLocationMap,LowerSusitnaRiver. . .,SusitnaRiveratSunshine,PreandPostProjectDischarge-StageFrequencyCurves.SusitnaRiveratSunshine,PreandPostProjectRiverStage. . . .SusitnaRiveratSunshinePreandPostProjectFloodHydrographs. .StageDischargeRelationship,SusitnaRiveratSunshine. . . .BraidedRiverGeomorphicUnitsSusitnaRiverSynthesizedCrossSection,DeltaIslands. .SusitnaRiveratDeltaIslandsPreandPostProjectDischarge-StageFrequencyCurve. . . . . . . . . ....StageDischargeRelationship,SusitnaRiveratDeltaIslandCrossSection.SusitnaRiveratSusitnaStationPreandPostProjectDischarge-StageFrequencyCurve.SusitnaRiveratSusitnaStationPreandPostProjectRiverStage. . . .SusitnaRiveratSusitnaStationPreandPostProjectFloodFrequency. . . . .StageDischargeRelationship,SusitnaRiveratSusitnaStation. . . . . . .-iii-38910111318192022232425 LOWERSUSITNASTUDIESOPENWATERCALCULATIONS1 -'INTRODUCTIONTheLowerSusitnaRiverisconsideredtobethereachdownstreamofTalkeetnatoCookInlet.AttheconfluencewiththeChulitnaandTalkeetnaRivers,theSusitnaRiverchangesabruptlyfromameanderingsinglechannelconfigurationtoapredominantlybraidedpattern.UpstreamofTalkeetnatotheproposeddamsites,theSusitnaRiverisbeingstudiedquiteextensivelyunderSubtask3.06-"HydraulicandIceStudiesllandSubtask3.07-lISedimentYieldandRiverMorphologyStudiesll•DownstreamofTalkeetna,areconnaissancelevelstudyisbeingcarriedoutunderSubtask3.10.Aprimeobjectiveofthisinterimreportistoquantify,asbestasispractical,thepotentialchangesintheflowregimeduringfloods.Vegetationandhabitatstudypersonnelindicatedthatestimatesofchangeinwaterlevelsduringvariousfloodswouldbenefittheirprograms.Therearecurrentlyonlytwostationsthathaveexistinghydrologicdata;SusitnaRiveratSunshineandSusitnaStation.Atthesetworeaches,theriverisconstrictedintoasinglechannelwhichisnotrepresentativeofthepredominantlybraidedriverpattern.Withrespecttopotentialchangesinwaterlevelsduringvariousfloodsunderpreandpost-projectconditions,thesetwostationswouldprobablyreflecttheextremecase.Therefore,athirdstationwasaddedtothisstudywhichwouldrepresenttheflowregimeinabraidedreach.Asamplesectionwasselected8,000feetdown-streamoftheWillowCreekconfluenceattheDeltaIslands.Thisr12/h- 1 - cross-sectionwassynthesizedfromareconnaissancefieldtripandhydraulicregimerelationshipswhichenabledestimatinghydrauliccharacteristicsunderpreandpost-projectconditions.WiththreesectionsintheLowerRiver,itispossibletointerpolatethefollowingresultstointermediatelocationsofinterest.r12/h- 2 - ".RIVERSTATIONLOCATIONMAPLOWERSUSITNARIVERF=======:::£;=f'-~'N~~=~!..:::£~b:GC?=o=!.',;=Gs=,s=!;J=L:="!=L-f'=N==~=...T=s==~:=~=..~==t;J=Yo=c;:=;============1A~~{~'IFigure1.1 2 -SUMMARYVariancesinflowandstageintheLowerSusitnaasaresultofflowregulationarereasonablyboundedbythisanalysisforopenwaterfloods.Themagnitudeofchangeforpreandpost-projectfloodsof-2,5,10and25yearrecurrenceintervalcanbeestimatedfromthisanalysis.Sincethedatabaseisscant,theproceduresutilizedinthisstudywerebasicandperhapsoversimplified.However,generallytheassumptionsmadewereconservativeandreflecthigherchangesinflowandstagethanmayoccur.AsummarycomparingeachstationispresentedonTable2.1.AtSunshine,thestageintheriverisexpectedtobe2.0to2.5feetlowerduringfloodswitharecurrenceintervalof2to25years.AtSusitnaStation,achangeinstageforthesamefloodintervalscouldvaryfrom1.9feetto3.2feet.ComparingthesetwostationstotheDeltaIslandStationshowsthatthepotentialdecreaseinstageforabraidedsectionwouldbelessatjustbelow2feet.Sincetheriverswidthincreasesmorewithanincreaseinstage,thisisexpectedforabraidedreach.Basedonthesethreepoints,estimatesofpostprojectstagechangescouldbemadeforintermediateriverreaches.Sunshineisrepresentativeofan~pstreamconstriction,Susitnastationrepresentsanarrowdownstreamsection,andtheDeltaIslandisrepresentativeofabroadbraidedreach.Therefore,otherriverreacheswouldhavestagechangesequaltoorlessthanSunshineorSusitnastationandequaltoorgreaterthantheDeltaIslandsection,dependingonthecharacteristicsoftheriverreachbeingconsidered.Localvariancesinriverreachesandeffectsofdebrisjamming,transitionalchannelchangesandothernaturalinfluencescoulddistorttheseresults.However,forthepurposesofestablishingr12/h- 4 - guidelines!itcangenerallybestatedthatstagesafterflowregulationwillbe1.5to3.5feetlowerduringfloods!dependingonthereachofriverunderconsideration.Additionalfielddata!thatisscheduledtobecollectedduringthe1981openwaterseason!shouldprovidesufficientinformationtocarrythisstudythroughanotherdegreeofrefinement.Proposedactivitiesfor1981consistof:oooooor12/hBreakupobservationsbyAcres!R&M!TES.Verticalaerialphotographyon3"x5"printsatvariouswaterlevels.ContinuousstreamgagingbyUSGSontheSusitnaRiveratSunshineandSusitnaStationandontheYentnaRiver.StaffgageinstallationandmonitoringbyADF&G.Fieldobservationsbyhydrologists,aquaticbiologists!terrestialbiologists,etc.RiverRegimestudiesbyR&MandAcres.- 5 - TABLE2.1PRELIMINARYESTIMATESOFPREANDPOSTPROJECTDISCHARGEANDSTAGEFREQUENCYANALYSISDevilsCanyonDamsitePFeprojectPostprojectRecurrenceInterval251025Q(ds)47,00061,00071,00084,000Q(cfs)15,00015,00015,00015,000SusitnaRiveratSunshineStationPreprojectPostprojectRecurrenceQStageQStageInterval(cfs)(ft)(cfs)(ft)296,00057.964,00055.95125,00059.279,00057.110146,00060.090,00057.625176,00061.0107,00058.5SusitnaRiveratDeltaIslandsPreprojectPostprojectRecurrenceQStageQStageInterval(cfs)(ft)(cfs)(ft)2105,00094.672,00092.75136,00095.690,00093.710159,00096.3103,00094.525193,00097.3124,00095.3SusitnaRiveratSusitnaStationPreprojectPostprojectRecurrenceQStageQStageInterval(cfs)(ft)(cfs)(ft)2157,00016.8125,00014.95204,00019.1158,00016.810239,00020.5183,00018.125289,00023.0220,00019.8Note:Basedonpreliminarydata,subjecttorevisionChangeInStage(feet)2.02.12.42.5ChangeInStage(feet)1.91.91.81.8ChangeInStage(feet)1.92.32.43.2r12/h- 6 - 3 -ANALYSESATSUNSHINESTATIONDuetoabsenceofanifloodrecordatthisstation,estimatesof2,5,10and25-yearfloodpeaksundernaturalregimeweremadefromregionalfloodfrequencystudiesconductedbyR&MunderSubtask'3.05.Completeregulationoffloods(uptoa25-yearR.I.)bytheprojectwasassumedforthebasinaboveDevilsCanyon.Thepost-projectfloodpeaksatSunshineStationwerethusestimatedasthesumoffloodpeaksfromunregulatedcatchment(ChulitnaandTalkeetnaRivers,plusSusitnabelowDevilsCanyon)andregulatedflow(assumedtobe15,000cfs)fromtheWatana-DevilsCanyondevelopments.Thisassumptionresultsinaconservativelyhighestimateofchangesinfloodpeaklevelsduetotheproject.Figure3.1presentsthefloodfrequencyanalysiswithrespecttodischargeandstage.Theseresultsaresuperimposedonacross-sectionalplotoftheriveronFigure3.2.Extensionsofeitherfiguresforrarerfloodsshouldbemadewithcaution.FloodhydrographshapesatSunshineweresynthesizedfromobservedsimultaneousflowsatGoldCreek,ChulitnaandTalkeetnagagestationsfornaturalconditionsandChulitnaandTalkeetnarecordsforpost-projectsituation.TheresultsshownonFigure3.3provideanestimationofflooddurationsunderpreandpost-projectconditions.AstagedischargerelationshipisshownonFigure3.4.ThiscurvewasgeneratedfromfourmiscellaneousmeasurementswhichhavebeenmadebytheUSGS.Continuousgagingthroughthe1981summerwillgenerateamorereliablecurve.r12/h- 7 - t;I:I:Ii1-·,._--Iiii,--Ii----1--·iiIi----1-----Ii!iii,-_.1----;!IIi!i!iI--,IiI51025pO100,----::::--.'::-:-.:.---1--,NOTE:BASEDONPRELIMINARYDATA,SUBJECTTOREVISIONRETURNPERIOD-YEARS~~I(~It-·-~-ul_sA_,T-:-~_A_H-~-~-R-V:-E-:-~-C-~-RU-Ic_T_~_~-o-~_I:-cY-T~SUSITNARIVERAT SUNSHINEPREANDPOSTPROJECTDISCHARGE-STAGEFREQUENCYCURVESDc:.;R&MCONSULTANTS,INC.MARCH19813.\.NOINCEA.QI!OLOO,.T.PLANNE•••UAvavo•• '....,..~-..,.--..,.---..,.----.--..,.-..,.--..,.---...,---..,.--...,...,.--------...!!,.iII1I,i,.iI";i,II!,,!,,1II,III,iIi,I"'1"(1:.II-~IAbl:.-------------------I-WI--'-..;-----t-~-i---~---+----'---_+-___+--_+_----------;....-------W1---+-__-,,__-++-~----~----------Il1..Z--------r-__------l--__:-+---+-:-----+-__--,--J-----T+----l----------+---------Ir.:'1--------+----+----'-+-----+-+-,-+--,-'--+------1--·---..:----__---'------------IJ:-1--------!-----'-----f--------t-------+---+-----------1C>I-WWl1..ZJ:l-ll.W0W~~X0a::a..a..«0I---·-~r__---__-----L--_+--_+_------+------_'l----__1511000800.V'\I-I,II"7\./\~\I!I\i-\1/~----:-:i,i'-//v!/400600STATIONING,INFEETNOTE:BASEDONPRELIMINARYDATA,SUBJECTTOREVISIONI200/1\'i/"I,\1+-'-'---l-----+---------+--------+---1------l~---f--+--_l_----i---·--;------1--'---------II20,iiiiIIi300SUSITNARIVERATSUNSHINEPREPROJECTPOSTPROJECTA~lmALASKAPOWERAUTHORITYR.t.QStageQStageSUSITNAHYDROELECTRICPROJECTyrs.cfs(ft)cfs(ft)--SUSITNARIVERATSUNSHINE296,00057.964,00055.9PREANDPOSTPROJECT5125,00059.279,00057.1RIVERSTAGE10146,00060.090,00057.625176,00061.0107,00058.5~L---IR&MCONSULTANTS,INC.MARCH19813.2.NOIH••"•.•lfOL.a.laT._LANN•••au"v."'OIlll. 1-----·-~t_j_-r-__,--t__-l-_j_·+_--l----0-+---...;---_t_·-~--+-·---'·--_+-+:-----t--.---.----~--.--.--+-----.-------...---.6'1---,.....;---\---'---\----"---;--:;,"""""........--+----.L---+----'--·--+-------I1----..-.:~--~-'-'l__--'~-':-+-.------.-'-----.,.I-i..-.~"",---j---~+-----,:--+--.--,--..-.-:..._.j_l_.,---.----'.-.-I"...,.......5..i/I......!"'......../Li/ 'r:..-~',---.",.,,"'c-;-----i"'''''.......--..--c.--.....--..--.r-..--.---.'-''''---,5f!-'--:.-,.....;--:=;;>""""./'-c--r--c----i---'----+,.....;---r-__-,-l-__----;----t----+---+---'-----\"..,,"50,,---:,,i:49,48-5-4-3-2-IPEAK2345TIME-DAYSLEGEND:--PREPROJECT--POSTPROJECTNOTE:BASEDONPRELIMINARYDATA,SUBJECTTOREVISIONIPD(@It--_A_t:--A---:-S_KA-=P~O-W_E-R_A_U_T_H,_O_R_'_TY---fliundsusI T N A H Y DROELEeTRICPROJE CTIf.SUSITNARIVERATSUNSHINEPREANDPOSTPROJECTFLOODHYDROGRAPHS1D~R&MCONSULTANTS.INC.MARCH19813.3ENOIN•••S.aOLOOlaT..LANN....aUIlltV.YD••_ ,f1_ Notes: 1.Rating curve interpreted by R&M Consultants based on the following four discharge measurements made by U.S.Geological Survey. 2.Add 208.35 feet to correct gage h~ight to mean sea level datum. ~ Discharge (ft.3/sec.) 37,400 64,600 171,000 27,400 Gage Datum 52.9 56.6 60.8 51.0 Date May 27,1971 July 2,1971 August lIt.1971 October 4,1977 -- I IlD~2~<;- ~$(7U 00 '0 <:Q r-"' ~o 82 UiUl ~c ~~iJ\ ~VI D'G) ~2 tr:I OO-J ~ tr:I ooUl H c~ G) D ~ <->-3 ~2 iJ\ ~n H 0 00. Z h:J tr:I tr:I >-3 VI VI STAGE-DISCHARGE RELATIDNSHIP SUSITNA RIVER AT SUNSHINE FIGURE 3 ..4I-I::::::;:p;::;J II I I ~. 'I I\. VIo 50,000 100,000 150,000 Discharge (cfs) 200,000 4 -SYNTHESIZEDCROSS-SECTIONATDELTAJSLANDSInordertocomparepreandpost-projectflowconditionsinthebraidedreachesoftheLowerSusitnaRiver,anexampleofthechannelgeometryisrequired.Arepresentativesectionthroughabraidedreachwasselected8,000feetdownstreamofWillowCreekconfluence.Areconnaissancefieldsurveywascarriedouttodefinebasicrivergeomorphicfeaturessuchaschannelwidths,relativeelevationsbetweengravelbarsandvegetatedislandsandicesurfaceelevations.Withthisbasicdata,itispossibletoestimatechannelhydraulicparametersutilizingregimetheoryorhydraulicgeometryrelationshipsfordominantdischarges.Dominantdischargereferstoadischargethatoccursatregularintervalsandshapestheriverchanneltoaccommodateit.Thewaterlevelassociatedwithdominantdischargeisusuallyequivalenttoabankfullstage(closetoincipientoverflowontothefloodplain),andiscommonlyreferredtoasthemeanannualflood(afloodthathasarecurrenceintervalof2years).Whentheconceptofdominantdischargeinbraidedriversisconsidered,thetermsbankfulldischargeandfloodplainshaveauniquemeaning.ThegeomorphicunitsofatypicalbraidedrivervalleyareshownonFigure4.1.Theterracelevelisaremnantofapastgeologicaldepositionanditisnotexpectedtobeinundatedbyfloodwaters.Fromtheterrace,thebankslopesdownontotheinflctivefloodplainwhichisinundatedonlybyrarefloods.Oldabandonedchannelswhichnormallysupportsavegetativegrowthoftenscartheinactivefloodplain.Braidedactivechannelsintertwineontheactivefloodplainwithlittleornovegetationexistingontheactivefloodplaingravelbars.Activechannelgravelbarshavearoughlycommonhorizontalmaximumelevationwhenviewedincross-section,whichdefinesthebankfullstage.r12/h-12- BANK..-/'INACTIVEPLAINGEOMORPHICUNITSOFBRAIDEDRIVERSINACTIVEFLOODPLAINrJd-----;--,BANKFULLISTAGEwACTIVEFLOODPLAINTO?OFGRAVELBARSDEFINITIONOFBANKFULLSTAGEBRAIDEDRIVERGEOMORPHICUNITSoc.;MARCH19814.1R&MCONSULTANTS,INC.•NGINEIIf...allfOLOO'.TaJOL.ANN....au.vayo"._1?_ BankfullstageisillustratedinFigure4.1.Thetopoftheinternalactivechannelgravelbardefinesthebankfullstagewhichhasalowerelevationthantheinactivefloodplain.Thesurfacewaterwidth(W)ismeasuredatincipientfloodingofthebarandthehydraulicdepth(d)isequaltothecross-sectionalarea(A)dividedbyW.Bankfulldischarge,asdefinedhere,isbelievedtobethedominantdischargeforbraidedrivers.Asthedischargeincreases,flowandstageinthevarioussub-channelsincreasesimilartosinglechannelrivers,untilthebankfullstageisreached.Anadditionalincreaseindischargedoesnotsignificantlyincreasetheriver1sstagebecauseofasuddenincreaseinwidthofflow.Afurtherincreaseinflowwillresultingravelmovingfrombarsintoflowchannelsandsubsequentlychangethechannelnetworkmorphology.Hydraulicgeometryrelationshipswereutilizedtodefinethechannelgeometryforeachsub-channelintheDeltaIslandcross-section.Thefollowingrelationshipsweredevelopedfromfielddatacollectedintruebraidedriverswhichhavefewornointermediatevegetatedislands(Drage&Carlson,1977).Presenceofvegetatedbankstendstoretardbankerosionandlateralmigration,therebydeepeningthechannelinordertoconveytheflow,thereforeupperlimitmeanhydraulicdepthsassociatedwithchannelwidthswasutilizedinthisstudy.Thisanalysisisonlyanapproximationwhichissuitableformakingrelativecomparisonsforproblemidentification.d0.33\W9 d2=Wor=d=0.63dord=1.6dmaxmaxW=4.66Qbi7orQ=w2.13AWd26.5=r12/h-14- where:disthemeanhydraulicdepth(feet)dis.themaximumdepth(feet)inasubchannelmaxQbfisthebankfulldischarge(cfs)Aistheflowareaatbankfull.(sq.ft.)Utilizingthefieldmeasuredrivermorphologicfeaturesofchannelwidths,miscellaneouschanneldepths,floodplainelevationsandvegetativecharacteristics,inconjunctionwiththeseequations,hydraulicparametersforbankfullconditionswerecomputedandarelistedonTable4.1.Inviewingthecross-sectionshownonFigure4.2,thereisacommonhorizontalelevationatabout95feet(assumeddatum)thatrepresentsthetopofgravelbarsandwasselectedasbankfullelevationforthebraidedchannels.Measuringthechannelwidthsfromthefieldsurvey,andutilizingairphotos,10channelswereanlayzed.Thefarwestchannel(No.10)isthemainsubchannelandthefareastchannel(No.1)isthesecondhighestrankedsubchannel.Intermediatechannelsarecomprisedofsmallerbraidedsubchannelsandmeanderingsinglechannelsthroughthevegetatedislands.Summingtheestimateddischargeofeachsubchannelproducedatotalbankfulldischargeof115,600cfs.Utilizingthebasicassumptionthatthedominantdischarge(bankfullconditions)isequivalenttothemean-annualflood(RI=2yrs.)wehavedevelopedonepointonthefrequencycurvewhichcanberelatedtostageforpre-projectconditions.Asacheckonthisprocedure,themeanannualfloodwasdeterminedfromtheRegionalFloodAnalysisshownonFigure4.3.Thetwovaluescorrespondreasonablywell,therefore,somesupportforthepreviousassumptionsisprovided.r12/h-15- Asflowsexceedbankfulldischargethewatersurfacewidthincreasesveryrapidly,andtherefore,thestagerisesataslowerratewithincreasingdischarges.Usingthemeanvelocityasdeterminedunderbankfullconditionsinconjuctionwithwaterwidthsandincrementingonefootatatime,aroughstage-dischargerelationshipwasdeterminedandisshownonFigure4.4.AdeterminationofrelativechangesinflowsandstagesatvariousfloodsfromFigure4.3canbedetermined.Referencingthecross-sectiononFigure4.2,theterracelevelwhichsupportsmaturetreesisatanapproximateelevationof98feet.Thiscorrespondstoafloodgreaterthana50yearreturninterval,whichseemsreasonable.r12/h-16- TABLE4.1HYDRAULICPARAMETERSSYNTHESIZEDCROSS-SECTIONDELTAISLANDS(8,000FeetDownstreamofWillowCreekConfluence)ChannelWidthMeanDepthMax.DepthAreaQbf(feet)(feet)(feet)(sq.feet)(cfs)1.5007.411.73,70021,0002.left2104.87.61,0003,3002.right1504.06.56001,6003.left2255.08.01,1253,9003.right1203.65.74301,0004.903.04.82706005.slough6.1406.09.58401,4007.705.08.03503008.left4006.610.42,64013,1008.right2204.97.81,0803,6009.702.84.420030010.8509.615.38,16065,500TOTAL115,600cfsr12/h-17- ~~~~o~9I~\4-.\.II-~'1:.~~m-e.~~~1~..III:::t~~1u~~C~It~ij~~~~a~111~"-~~..."'"~t~~i~Qt~snb..~~~-J~Q<~lU....~fJIl~~....t~..J~~~Q~g...,j~~III~....!Iq!It'i~.......~cr-~.Nr-~II}....-"l~~\\)fJj~e()t\l~lr)~~~1~8~~~:t~It~~~-()~~~\q1')..~~~~~~~~~~re~~11l!~~~t~,~~~..J~~~.J~~~Q-I..:Q~~~~1lJ~...~10f;1~ti~b.1dlu~l.ll~III~1lI~~~~III1~~~~~~~:z~~~iit~~~Q~~:s~~\Ji!~<<~~~~~~~<~~~~1\<~III~~~~!~~~~~~~~~~~~~~"{~~"\~~~lI)~~...J~....,j...J~~~.\J~'U~\I~\l>\l11)~\)~~~~\I:t:\l\lr-----"lr---'lr---"1r---tr--:-"lr-----'\r---"'\A.\~r-------Jr----:--rIOf-OOZOrOO40+0050t"006o-roo701-00.80+0090+001J0i-OOI'2.Di-OO/401"00.150""00/60+1.-4.ALASKAPOWERAUTHORITY'"""~..,,-~~-,,;"Jt~l!$i,~~~---':",,%;f"$~"1i¥k'$!%~'""~0""""~"SUSITNA:.RIVERi_.lJ$%',_t;,~J',~'",'IZ~9z:!=!!9~~SECTIDNCELTA~isi.ANCSIIRNOTE:.."ELEVAtIoNsBAS€OONASSUH€O.t:::/14TUM•BAFlKFULLELEVArIONIS95.0F'T...CRoSS,sECTIONaA5E(;:)ONp?eCONNAISSANCJ!!!,.I="IELO.su~VEYANt::?R~/ME:R'ELATlON.$HIPS,ALLELeVATIONSANDSTATiONSAPPRcn<I/'MTE:..1INc:>IG4T£S7?:;>PI~ELEVEl-ONMAR.I9,I9BI..~R'o.sssecTIoNLOGAr-EOBooo't;;>owNS"I"Re:AMOF~LLokl"CREEKLZONFlUE:N<:.E. 106tlm'"EITI-I;;lt:~~~f.t~:'r:~;:i;:~'r~ic:~~",l~~j;m::l.j."-::~~ti:·tT!'Ji-I,+;-~,~~r:J""ri+::'~'-:'~~:"'-'i~:l--'f-::":l-,='~~,,-:.;-·;!:!.·:.:-,:..._-::~-,j~~==-!-:~~:l::~r::~:~~"l'f·~J::;.:c:~:'=i~i·i=l~f"~:.:r.~~'.f~~~·····~~·w',ifi=j~~L!:.t>:::E,.;:-i~i~r.=,==I':-:"i_t·...l.;_:.f:r_=J:_==::'-j-=:=:~"I-fl:~~=_:f1''-',-',,1-:'::',,'"'1'==,~~==..•-=.::;==-=::.'---,--It-t-!l-++t·t·+:t't-:',T;J::IT+H-----,--,-H~~,~#Eftng.~i,ffif4'tII,I_!,_Ef1+tl+9=ffr-=t=+-l,,110+;'-H-rr~+H-+;!,I_Ii'-+-H+H:~+l+1I,+-d-t,--1=t+"LL';-lLJLL::!I~"'+1I_L.LL',,_LLH-,-I',I"",..-t-I',~'nf--,'1I'!T'TT'"1+4Urr,,-r-I ,'r,-1"-t1.,..T--1++hiTi-r-t-.1,-98.I,' ,!1-'I",'I,r':'1'.JH-j.••'II'trn-r-t-+-!!i;tIt!i!ttl~1+4-++1+++:t-H~·-t..L-tl±ffi#.ttl+I'~~.;I;,, ,:I·..·i---+hH-+-+H+t--t-+-+--j--j-+:t+':I-97<.>iIIiW--ltJTJ++H+JI::,LI-J.,.I4-:f-J-.+-+--.J+I-l-J..-I+J...J+I-++-++-I-l-iH+I,H-il-+--ITinIIIlIIIIIITIIIIIII"96I-~':;WiI !Ii1tH+++I1+II;rIiH:~~I I Ir"t',T'HT1TT~illT.'I IiI!l.L.~1-+++H+'I+t,,!TI~,Irrl!thr.J,-irl.H-rl:II....JEdT"1'1~95I~105.111;,llllnHFn"IIII"1Tt~~~.:-~[!i--=lrH'94~~sff1:~.~-+-=---Ff:t=E~-~1-:-~(J)::>'-fl'-.-,.,.-,t:q:.L1-.'93~h~ft-o..-,c"-l-,--;:t:J=T-,---x1::!:::1:11-_cr;H<t-i+f-~f:it•::EJ'!'-II--W-t-','liit~-tI-Wit++jt--+-i-·,+-r--r:m~T'1+Tl-I-4!--'--,,+If--f-I-r-'--+--.,..i-f-+-,-.-,~.r=t=F=P=i==.rr;!•1-+--.l-H--~'-~ltl--!-.---HH++t;JII_-~f--I!RETURNPERIOD-YEARSNOTE:BASEDONPRELIMINARYDA1A,SUBJECTTOREVISIONA~I~II~--~-U-:-~-TS-NK-A-A_H-~-~-R-:-V-EE_lR_Ec-~-R-~-:_H_?-~-O-~_IE-Tc-~--ISUSITNARIVERATDELTAISLANDSPREANDPOSTPROJECTDISCHARGE-STAGEFREQUENCYCURVED'R&~CONSULTANTS,INC.MARCH19814.3•...,OIN....alfOI..OQlaTa~I.-"'''''N•••aua",aYO_.-19- S TAG E ~DI SC H AR G E"R ELATID NS HIP SUSITNA.RIVER DELTA ISLANDS CROSS SECTIDN ,FIGURE 4 ..4 iD~!~~ ~n ~ ~o b2~Ulole ~!:j D:i ~2 ffi-f l/lUl~I c~ Di~1I I .j..I 100QJ QJ Ii. s:: ·rl .j..I..r:: tTl ·rl QJ :I:95 QJ tTl ((j 0 90 ~;.. c .... _IU'C:JI i • I ~. II I 50,000 100,000 150,000 200,000 Discharge (cfs) 5 -ANALYSESATSUSITNASTATIONUsingavailableUSGSstreamflowrecordsatthisstation,peaksandhydrographshapesweresynthesizedforfloodsofdifferentreturnperiods.Post-projectpeakswereestimatedinamannersimilarto'thoseatSunshineStation.Figure5.1presentsestimatedfloodpeaksforpreandpost-projectconditions.Usingthese,itispossibletoestimatetheeffectoftheprojectonrecurrenceoffloodpeaksandcorrespondinginundation.Theresultsarealsosuperimposedontherivercross-sectiononFigure5.2,withthepre-projectstagesplottedonthefeftandpost-projectontheright.FloodhydrographshapesarepresentedonFigure5.3,whichcanbeusedtodeterminedurationofinundationundervariousfloodingconditions.Figure5.4presentsastagedischargerelationshipthatwasdevelopedfromUSGSmeasurementsattherecontinuousgagingstation.GageheightscanbereferencedtothecrosssectiononFigure5.2andfrequencycurveonFigure5.1.r12/h-21- !--I,ii·---.!r!iiIiiIi!iI!i5/02550100RETURNPERIOD-YEARS2Iii'-IJj:i,Ie!.:i~·:.L.f'i:l:,.\J:;:I~::.::=i.-..'1i~iI:iT'--~~J;-:.H'Y~-;-'l-"+~t-:++.,·t·~~,,·-!.i,::ii.:,.:'-:=.,;ei.ci.'t..,.:'.i.:'T,f:'I.I:'.",.,NOTE:BASEDONPRELIMINARYDATA,SUBJECTTOREVISIONSUSITNARIVERATSUSITNASTATIONPREANDPOSTPROJECTDISCHARGE-STAGEFREQUENCYCURVEoR&~CONSULTANTS.INC.MARCH19815.1ENOIN••RaOEOl..Oa'STaPLANN.....u.v.....o••-??- wC><tC>-....IC>WI-..-,--;-_..-,.-....•iII.j-/2pO..•..Ie00__,.~eooI-~..-.'WIDTHINFEET. j .,11·1,tjIOO__.---_.··---l-----1lc--'--,'.'-J:li:wo....wWIJ..ZSUSITNARIVER·ATSUSITNASTATIONNOTE:BASEDONPRELIMINARYDATA,SUBJECTTOREVISION251025PREPROJECTQStage(cfs)(ft)157,00016.82~00019.1239,00020.5289,00023.0POSTPROJECTQStage(cfs)(ft)125,00014.9158,00016.8183,00018.I220,00019.8.PIOALASKAPOWERAUTHORITYIIIU1"'--S-USIT-NAH-YOR-OELE-CTRI-CPR-OJEC~T-SUSITNARIVE:RATSUSITNASTATIONPREANDPOSTPROJECTRIVERSTAGEDo.;R&MCONSULTANTS,INC.MARCH19815.2.fIIte,..........OLO.laTa..L.au.v.ve-a jIi:,---;-il'-,-"------I-----''-J--1--.--;-+----++--'-'-+-1!,\"-,:1!I'"lII'1/'~i.......:i..........,/:":"-.....1.....,,10YIiSP(ST...."...'VO;>1,'.................:-'----..........I.....lI),i--'.lK,-,.,........-lI!'-!-..I--.......I~IIh"......:-.....-..................""'......--'.,/'./l,/./I,.,/vI-l1Jl1Ju..Z:IiIII::!I2 34 5,[IiJiIiI,I!II 3t-~-+---+----t---:-.-:-'-i:"'+---+--+-:--+-ri-+-:--t-+-t-+-:-rl-;--i--"-i-+-+-+-+---+'--:"'-I:iiTIMEDAYSLEGEND-PREPROJECT--POSTPROJECTNOTE:BASEDONPRELIMINARYDATAJSUBJECTTOREVISION~~IrnIt--~-u-~-~-TS-NK-A-A_H-~-~-R-V:-E-:-~-C-~-R-~-:_H_p_~-o-~_I:-cY-T---fSUSITNARIVERATSUSITNASTATIONPREANDPOSTPROJECTFLOODHYDROGRAPHS0"",R&MCONSULTANTS.INC.MARCH19815.3.NOtNCIEJllllIl••OLOGllaT._LANNt::••$U'll".VO".-')"- /,....'\1\\\~'~0020~0D-O0(V)--II-me(02I-000m~0-L!")l-e(Ne(2.JI-W-"0IIm'¢00:1•~In0W0mNl!Jw,-..III-mII~e(<I:ou:1o~0Il!J!,...(})II0-0-U-L!")HWIL.-lm..c:m>uUl-0'-;D-ClII0I0W0<I:~Cl002.-lc(l-I--mm0:10m0~0L!")oNL!").-lo.-lof======:R=-~-=~~~~~==!-~~~~O::=:N::==:='=S=:=U:=:==LT=A~N:==T:==S=J==1N=C==.=========1A"PDrPIENG"'F."'5.GEOLOGISTSPLANNE<1SSURVEYORSHUn[0-25- 6 -LOWERSUSITNARIVERBASINCHARACTERISTICSAspartofSubtask3.05-FloodStudies,aregionalequationwasdevelopedtodeterminemeanannualfloodflowsbasedonbasincharacteristics.Theresultingequationwasselectedasbeingthemostrepresentativefordeterminingthemeanannualinstantaneouspeakflow:Table6.1listsasummaryofbasincharacteristicsatvariouslocationsalongthelowerSusitnaRiverthatwereusedinthisstudytodeterminefloodflows.ItisinterestingtonotethevariancethatexistswithintheSusitnabasin.Forexample,thetwomajorwesterntributaries,ChulitnaandYentnaRivers,havethehighestpercentageofglacialarea.SusitnaRiveratGoldCreekhasthelowestpercentageofforestedarea.Table6.1isagoodreferenceforgeneralcomparisonofbasincharacteristics.Aforwardsteepingmultiplelinearregressioncomputerprogramwasutilized.Twelvewatershedparameterswereconsidered,including:drainagearea,mainchannelslope,streamlength,meanbasinelevation,areaoflakesandponds,areaofforests,areaofglaciers,meanannualprecipitation,precipitationintensity,meanannualsnowfall,andmeanminimumJanuarytemperature.Themostinfluentialparametersinpredictingthemeanannualinstantaneouspeakflowaredrainagearea,streamlength,areaofglaciers,meanannualprecipitation,andmeanannualsnowfall.DrainageArea(mi2)StreamLength(mi)MeanBasinElevation(ft)MeanAnnualPrecipitation(in)MeanAnnualSnowfall(in)D.A.=L=E=MAP=MAS=7.06(D.A.)+46.36(L)+697.14(E)+200.15(MAP)-49.55(MAS)-2594.44Q=Where:r12/h-26- misc6/p1 TABLE 6.1 LOWER SUSITNA RIVER BASIN CHARACTERISTICS FOR MEAN ANNUAL FLOOD CALCULATIONS Drainage Area Glacial Area Forested Area Lake Area Mean Annual Mean Annual Mean Minimum Stream Precipitation Snowfall January Temp.Length D.~.G F LP M.A.P.M.A.S.J L (mi.)(%_)--(%)(%)(in.)(in.)(OF.)~ Susitna River at 19,400 12 23 2 43 167 -4 301 Susi tna Station Local Area:Susitna Station 640 1 60 5 30 70 0 to Delta Islands x-section Skwentna River nr.2,250 16 34 5 43 140 -5 98 Skwentna Yentna River nr.3,930 20 12 4 50 150 -5 Susitna Station Delta Islands x-section 12,580 9 23 1 41 182 -3 281 N -..J Local Ar'ea:Delta Islands 1,080 1 60 5 30 70 0 x-section to Sunshine Susitna River at 11,500 10 19 1 42 193 -4 224 Sunshine Local Area:Sunshine 764 0 90 2 30 50 0 to Tal keetna Chulitna River 2,570 27 22 1 55 250 -5 87 Talkeetna Tal keetna River nr.2,006 7 25 0 70 150 -2 90 Talkeetna Susitna River at Gold 6,160 5 7 1 29 200 -4 189 Creek Local Area:Gold Creek 350 0 -0 20 -0 to Devils Canyon Devils Canyon 5,810 5 7 1 29 200 -4 REFERENCESDrage,B.T.andCarlsonR.F.May1977."HydraulicGeometryRelationshipsforNorthernBraidedRiver",ProceedingsofThirdNationalHydrotechnicalConference,CanadianSocietyforCivilEngineering.r12/h-28- r12/hAPPENDIXA-29- J=t&MCONSULTANTS.INC.5024CORDO'fA•80x.6087•ANCHORAGE.ALASKA99502.PH907-279-0483.TLX090-25280ENGINEERSGEOL.OGISTS·Pl.ANNERSSURVEYORSJanuary30,1981ProjectManagerSusitnaHydroelectricProjectAcresAmericanIncorporatedLibertyBankBuildingMain@CourtBuffalo,NewYork14202Attention:Dr.IanHutchisonRe:Subtask3.10,LowerRiverStudies,FlowRegimeDearIan:R&MNo.052310BasedontheregulatedflowsreceivedfromyourofficeJanuary16,1981wehavetabulatedandplottedtheprobablemeanmonthlychangeinstageexpectedontheSusitnaRiverbelowtheproject.IntableIaretheflowsandchangeofstageexpectedwithWatanaDam,andtableIIisbothWatanaDamandDevilsCanyonDams.Inaddition,tohelpillustratethedatainthetwotables,themeanmonthlydischargeandstagehydrographsareenclosed.ThesehydrographsindicatethepreliminaryestimatesofchangethatcanbeexpectedatthethreegagingsitesontheSusitnaRiver,locatedatGoldCreek,SunshineandSusitnaStation.HopefullythisinformationwillassistinquantifyingthepossibleeffectscausedbyregulationinthoseareasofconcernontheLowerSusitnaRiver.Ifyouhaveanyquestionsorcommentsconcerningtheenclosedinformation,pleasecontactmeorBobButera.Verytrulyyours,R&MCONSULTANTS,INC.TimRenschlerSeniorHydrologistTR/jjxjANCHORAGEFAIRBANKSJUNEAU -,-,0e4rEnt::"IXIr_-.....'''-;',•.''-c-.CD~'b~~2!l'19&1;_s~tyetiit~~R&MtoMUi·~'S;l.ttm'"---damtaf')".!f1ll'!.m.-2d~e1tous.-mathe'flwregf~'h'l.tbt!l~,_~~;Susf-tM~Mtur'alaBOregutatt!dflow~ttnftS"'::~,7;-C,_:':~:~<:~"">-.~..~.~.-..-:-";--".,....~Theestf~ted_~~'-te¥~ls~~-f~tr~t4bT~.ttao~~:the.q14!~1'"a\"eaJ,!Pl'fcabTf!onlyfofath&oPen-water'season(~th~Nf~r)..Forperl~wftn't~er'in1fJeMY"".~are*'estJIbUshedratf»gcurves.Furth~~.forwinterccndftfOffS.ft1sex~thatthedisenargeandtfmfngellf~verfcmatfouafter,.'"~latton,"11hedifferent~~tM1m"1JlamditfOftS'J>S1Udfes':havenot~se6!ufffefentlytocalculateprecfs!!level~:':u~1~amdftfons.bt.tttfteo~rI1l~lswfn,.;';,'st~nlrlfill~"'I!nl.tothosf!ealeulatedwf,~teTratiftlCUfYeI.*,-._,-"~..-.'-".~~-~•.-..-....'....~""",-~".--....-...<-•.,-........,'".."•.....•.•-."l?urfng~winter,J'1ver,tagesllloothundernaturalendregulate(!flows.wiltb@td'at~thannotedinthe$~tablesduetothe~!~~of'tc~..Pleaseen$Ur'ethatf:tle~r'$fnthetablesInterpreted~tlyd~aibedffttnt'stett.e:r...Yours.;tt1Ity." susi4/p2 TABLE I WATANA DAM ONLY PRELIMINARY ESTIMATES OF DOWNSTREAM STAGE CHANGES Susitna River at Gold Creek Susitna River at Sunshine Susitna River at Susitna Station Preproject Post Project Change Preproject Post Project Change Preproject Post Project Change Q Stage Q Stage In Stage Q Stage Q Stage In Stage Q Stage Q Stage In Stag (cfs)(ft)(cfs)(ft)(feet)(cfs)(ft)(cfs)(ft)(feet)(cfs)(ft)(ds)(ft)(feet Oct.5,639 6.5 8,224 7.3 +0.8 13,690 47.5 16,275 48.3 +0.8 30,050 7.3 32,639 7.6 +0.3 Nov.2,467 4.6 8,276 7.4 +2.8 5,829 44.5~';11 ,638 46.7 +2.2 12,660 5.P';18,467 5.8*+0.7 Dec.1,773 3.6 8,617 7.5 +3.9 4,199 43.8~';11 ,043 46.5 +2.7 8,210 4.3';'('15,058 5.4';'(+1.1 Jan.1,453 3 .O~·(8,302 7.4 +4.4 3,498 43.4*9,180 45.7 +2.3 7,905 4.3*14,754 5.4';'(+1.1 Feb.1,235 2.5';'(7,588 7.1 +4.6 2,952 43.I"/(9,305 45.8 +2.7 7,040 4.2~'(13,390 5.2';'(+1.0 Mar.1,114 2.2';'(6,613 6.8 +4.6 2,631 43.O~'(8,130 45.3 +2.3 6,320 4.1';'(11,819 5.1';'(+1.0 Apr.1,367 2.7*5,522 6.4 +3.7 3,177 43.2';'(7,359 44.9 +1.7 6,980 4.2';'(11,133 5.0';'(+0.8 May 13,316 8.7 7,374 7.1 -1.6 27,717 51.1 21,775 49.6 -1.5 60,460 10.3 54,520 9.8 -0.5 June 27,927 11.1 9,186 7.6 -3.5 64,198 55.9 45,457 54.1 -1.8 123,700 14.9 104,956 13.7 -1.2 July 23,853 10.5 13,183 8.6 -1.9 63,178 55.8 52,508 54.8 -1.0 131,930 15.3 121,261 14.7 -0.5 Aug.21,478 10.2 18,874 9.7 -0.5 55,900 55.1 53,296 54.9 -0.2 110,840 14.0 108,236 13.9 -0.1 Sept.13,171 8.6 13 ,036 8.6 0.0 32,304 52.1 32,168 52.0 -0.1 65,963 10.8 85,827 10.8 0.0 *No stage discharge relationship available for winter months.Estimates based on extrapolation of rating curve to low flows susi4/p1 TABLE II WATANA &DEVILS CANYON DAM PRELIMINARY ESTIMATES OF DOWNSTREAM STAGE CHANGES Susitna River at Gold Creek Susitna River at Sunshine Susitna River at Susitna Station Preproject Post Project Change Preproject Post Project Change Prepr;oject Post Project Change Q Stage Q Stage In Stage Q Stage Q Stage In Stage Q Stage Q Stage In Stag (cfs)(ft)(cfs)(ft)(feet)(cfs)(ft)(cfs)(ft)(feet)(cfs)(ft)(cfs)(ft)(feet Oct.5,639 6.5 8,186 7.3 +0.8 13 ,690 47.5 16,237 48.2 +0.7 30,050 7.3 32,602 7.6 +0.3 Nov.2,467 4.6 8,818 7.5 +2.9 5,829 44.5;'~12,180 46.9 +2.3 12,660 5.P\-19,009 5.9*+0.8 Dec.1,773 3.6 9,251 7.6 +4.0 4,199 43.8;'~11,677 46.7 +2.9 8,210 4.3;'~15,692 5.5;'~+1.2 Jan.1,453 3.O;'~8,522 7.4 +4.4 3,498 43.4;'~10,567 46.3 +2.9 7,905 4.3;'~14,975 5 .4;'~+1.1 Feb.1,235 2 .5;'~9,008 7.6 +5.0 2,952 43 .1;'~10,724 46.4 +3.3 7,040 4.2;'~14,809 5.4*+1.2 Mar.1,114 2.2;'~7,478 7.1 +4.9 2,631 43.0;"11 ,063 46.6 +3.6 6,320 4.1*14,752 5 .4;'·+1.3 Apr.1,367 2.7-:'6,629 6.8 +4.1 3,177 43.2*8,438 45.5 +3.3 6,980 4.2-:'12,240 5.1-:'+0.9 May 13,316 8.7 8,690 7.5 -1.2 27,717 51.1 23,090 50.0 -1.1 60,460 10.3 55,836 9.9 -0.4 June 27,927 11.1 10,411 8.0 -3.1 64,198 55.9 46,681 54.2 -1.7 123,700 14.9 106,181 13.8 -1.1 July 23,853 10.5 10,052 7.9 -2.6 63,178 55.8 49,377 54.5 -1.3 131,930 15.3 118,131 14.5 -0.8 Aug.21,478 10.2 15,088 9.0 -1.2 55,900 55.1 49,509 54.5 -0.6 110,840 14.0 104,450 13.6 -0.4 Sept.13,171 8.6 12,666 8.5 -0.1 32,304 52.1 31,799 51.9 -0.2 65,963 10.8 65,458 10.8 0.0 *No stage discharge relationship available for winter months.Estimates based on extrapolation of rating curve to low flows SUSITNARIVERATGOLDCREEK1510-+JQ)Q)4-:Q)C'(\l5-+Jtr.l---....:.----.-......--JII--II'""-"'.-....::_------0DJFHA MJ JAS0 NDMonth3025~20u0/-,/,0,~15/,/'\://Q)/tJ1/~10./.G..../U-------/....".,~.,-----Ul---•.-iCl50DJFMAMJJAS0 NDMonthnlln[~ALASt\APO~~lERAUTHORlTYRegulatedUnregulatedhJilPSUSITNAHYDROELECTRICPROJECTMEANi>10NTHLYLowerSusitnaRiverDischarges&stagesHatanaDamOnlv_glJ£'~~Jan.28,1981::u~~.c.:2'~Q~!-!l:T~~_-':~'w!!';!}?~ SUSITNARIVERATSUNSHINE""...------........"..-'\/'\/'\I~I~I/I/i/'IV"-......._-------------."..",/5055illt::l"'Cii.j..IUl454Jillill4-140DJFAMMonthJ JASoND/---/------------/'DNo1\\\"-."""-........------SAJJ".,,----",'\/''\/'\/1~III/I//VH~1onthAFJ605040UJ4-1U00300...-iill20t::l"':y!ll......uUJ10•.-1a0DALASKAPOV/ERAUTHORITYupnrQ1~~tJ!Lll--s-U-S-IT-N-A--H-Y-DR-O-E-L-E-C-T-R-I-C-P-R-O-J-E-C-T---1~1EAN~10NTHLYLowerSusitnaRiverDischaraesandstagesJ;\'atanaDamOn1vJan.27,1981~0j~rr01~1R&MCONSULTANTS,INC.......U.....lI;."".u-.u~oa••l•..............."..............v....;-"', -SUSITNARIVERATSUSITNASTATION15'\"'\'\'\'\10+JQ)Q)"l!-'5Q)1:7,C1l+J(J)O-+-.---r------r--.-----;r----,.---.,.----,.----.--,---r---r----,DJFMAr1MonthJJASoN D15/-/"/'//I///I////'I'I-----------"--'"0-l-----r------r--.-----;r---,.---,-----,.---,---,---r---r----,~~4-'u010ooDJF MAJAs oND['1onth-----Regulated_____UnregulatediJP'nIQALASKAPOWERAUTHORITYflUUWSUSITNAHYDROELECTRICPROJECTMEAl"!~!ONTllLYLowerSusitnaRiverDis~~~rnAS~StaqesVolatanaDamOnlyJan,27,1981-~~'---------IR&MCONSULTANTS,INC...................a~u...OO••ll11...\,.A...."-~...1IiI"'......w••,·..., SUSITNARIVERATGOLDCREEK15:zJ10CJQ)4-i------------5-------"'"----------0DJFMAMJ JAS0NDMonth302520......15•en/.....4-l/"-()/"-,010//~0.,,---.-----,0...-.......,'-------....;----------..................-....-Q)5tJ.$.-IrU..c()en0'r-iClDJFMA1:1JJAS0N D~1onth-----Regulated---~Unregulatedftq~rn,IALASKAPO\VERAUTHORITYHuH[u!--S-U-S-I-T-~J-A-H-Y-O-R-O-E-L~EC·-T-R-IC--=P-=R~O-:J-=E-=C-=-T:-----j~1EANc·l0NTHLYLowerSusitnaRiverDischarqedandStagesDevilsCanyonandWatanaDarnsJan.27,1981J2~1~&MCONSULTANTS,INC.......u(,,;.u,,(,,).;.I;-.'••.~&_..~-..·t_.·'"'... --SUSITNARIVERATSUNSHINE5550+J<lJ~45--..:..._-----------.....-------~"/''\/\./.:;/J//40DJFMA~·1JMonthJASoN DDNo~:\\'\"-.........'.........------sAJJM----....,"...--"-/\I\/\/\/\/////'/A----------------"'"'-30405060~20uoo~10.<lJ0':..;0m..c::uUl'''-;DJF0t-1onth-----Regu1ated__---'unrequ1tedn,',~~,[n"_A_L_A_S_~_...A_P_O_W_E_R_A_U_T_H-=-tO=-:-R-=!.....-:-'Y-:-----1iiU!_U_U_'''-SUSITNAHYDROELECTRICPROJECT!'lEAN~'10NTHLYLowerSusitnaRiverDischaraes&StaaesDevilsCanyonandWatanaDamsJan.27,1981~l01L1R&MCONSULTANTS,iNC..................."""'1.00,.1""_~£" SUSITNARIVERATSUSITNASTATION/--/////I'I1015I.~/I----------------/(J.Jty,ro.j.JCfloDJFAMJMonthJASoND15--.,/......./.......I"/\/\/\/\/'~/~'IIf---------------oUl~Uoo010or-l-----Regu1ated___Unre<]u1atedDNosAJrALASi(APO\VER.AUTHORITYl~n~rt1fHlr~c~~~11-------'----------------mn~USUSITNAHYDHOELECTRICPROJECTHEAN~10NTHLYLowerSusitnaRiverDischar~psannStaaesDevilsCanvonandWatanaDamsf.1JMonthAMFJDJan.27,1981J2\~f\jl,-_R&MCONSULTANTS,INC.......'"'Wl.O·.tllt_;...