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HomeMy WebLinkAboutAPA473..J _v~--, ::=v ,.....~------------------------t-LD-=.... 0) ,SUSITNA HYDROELECTRIC PROJECT TASK 7 -ENVIRONMENTAL SUBTASK 7.04 WATER RESOURCES ANALYSIS A PRELIMINARY ANALYSIS OF POTENTIAL NAVIGATIONAL PROBLEMS DOWNSTREAM OF TH E PROPOSED HYDROELECTRIC DAMS ON THE SUSITNA RIVER MARCH 1982 TK Prepared for: 1425 [iJ.58 A23 no.473 1 ALASKA POWER AUTHORITY_~ ..- SUSITNA HYDROELECTRIC PROJECT TASK 7 -ENVIRONMENTAL SUBTASK 7.04 WATER RESOURCES ANALYSIS A PRELIMINARY ANALYSIS OF POTENTIAL NAVIGATIONAL PROBLEMS DOWNSTREAM OF THE PROPOSED HYDROELECTRIC DAMS ON THE SUS IlNA RIVER Prepared by Paul Janke Water Management Section Div.of Land and Water Management Alaska Dept.of Natural-Resources ,Ece'VE fEB 2219ii utnfY Branch of A'as\(an Geo\og\ ~nc Prepared for Acres American Incorporated Buffalo t New York Janua ry 6,1982 Revi sed:March 5t 1982 ARLlS Alaska Resou rees Librnr)'&Information Services LIbrary Buildjng,Suite 111 3211 Providec.ce Drive Anchorage.AK 99508·4614 TABLE OF CONTENTS S~y • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 INTRODUCTION.• . • . • • • • • • • . • • • • . • . • . • • . • . . . . . . • . • • . • . . . . . • • . . . . • 3 DISCUSS ION.• • • . • . . . . • . • • . . • • • • . • • • • • • . • • . • • • . . . • • • • • . . • • • • • • . . 5 Site Selection,Data Collection and Data Analysis -Upstream of Talkeetna......................5 Summary and Conclusions -Upstream of Talkeetna..........8 Site Selection -Downstream of Talkeetna •.~• •• ••.•. •• •• • • 9 Data Collection -Downstream of Talkeetna................10 Data Analysis -Downstream of Talkeetna..................11 Summary and Conclusions -Downstream of Talkeetna........16 r- I I I I 1 ,!List of Figuresil Figure 1 Cross Section Number 32 2 Cross Section 32,Stage-Discharge Curve 3.5 Monthly and Annual Flow Duration Curves,Susitna River at Gold Creek 4 Cross Section LRX-TKA1 5 Cross Section LRX-KTA2 6 Cross Section LRX-KTA3 7 Cross Section LRX-WL01 8 Cross Section LRX-WL03 9 Cross Section LRX-ALEX 10 Cross Section LRX-TKA1,Stage-Discharge Curve 11 Cross Section LRX-KTA2,Stage-Discharge Curve 12 Cross Section LRX-KTA3,Stage-Discharge Curve 13 Cross Section LRX-'WL01,Stage-Discharge Curve 14 Cross Section LRX-WL03,Stage-Discharge Curve 3.7 Monthly and Annual Flow Duration Curves,Susitna River at ~~Sunshine I I I List of Tables Table 1 Cross Section 32,Stage-Discharge Data 2 Cross Section 32,Percent of Time Discharge,Required to Maintain a 2.5-foot Depth of Flow,is Equalled or Exceeded 3 State-Discharge Data,Downstream of Talkeetna r- I I r I I r- I 4 5 Downstream af Talkeetna Percent of Time Sus~tna River Discharge at Sunshine,Required to Maintain a l.5-foot Depth of Flow, is Equalled or Exceeded Downstream of Talkeetna,Percent of Time Susitna River Discharge at Sunshine,Required to Maintain a 2.5-foot Depth of Flow, is Equalled or Exceeded ---~---------- - SUMMARY A review of aerial photographs,river cross-sectional data,and simulated water surface profiles indicates that the proposed Susitna hydroelectric project is not likely to cause navigational problems in most areas above Talkeetna under Case D postproject flows (minimal impact on fisheries).Case A streamflows (maximum power production)are likely to cause periodic navigational problems during the months of August and September. The major area of concern is a broad shallow reach one to three miles below Sherman,where the main channel of the Susitna River crosses the floodplain.The simulated flow is 6,500 cubic feet per second (cfs)and the depth is estimated at about 2.5 feet for this cross section indicating that the channel is navigable.Navigational problems may be encountered in about one year out of three in August and in about one year out of two in September in this reach under Case A postproj ect flows and in about one year out of 10 in June under Case D.Visual examination of aerial photographs from nearby areas without cross- sectional data indicates that these unsurveyed areas also may be non- navigable.Additional study in the Sherman reach is warranted during Phase II engineering and environmental studies,as these conditions are based on limited data. Cross-sectional data were gathered on the main channel of the Susitna River below Talkeetna,on sloughs and side channels used for river access near Kashwitna Landing and Willow Creek,and at the upper access channel to Alexander Slough.While stage-discharge data at these sites -1- are very limited,initial analysis indicates that operation of the dams would have no significant negative impacts on navigation in the main channel below Talkeetna or on access at Kashwitna Landing.At access channels near Willow Creek,it appears that there would be minor nega~ tive impacts in May for Case D.Case A streamflows are higher than Case D during May,thus navigation during this month is less likely to be adversely affected near Willow.Between the months of June through September,access channels to Willow Creek should be navigable. Data are insufficient to completely define the flow required at Susitna Station in order to keep upstream access to Alexander Slough open,but the decrease in stage is less than one foot for both Case A and Case D postproject flows. -2- - .~ INTRODUCTION Will the operation of the proposed Watana and Devil Canyon hydroelectric dams on the Susitna River restrict the movement of vessels during the ice-free months downstream of these dams?It is the intent herein to provide a preliminary determination of whether navigation would or would not be adversely affected downstream of the Devil Canyon dam site,and, if so,to define in which river segments and during which period of the year navigational problems are most likely to occur.Specific reference will also be made regarding the possibility of postproject streamflows improving navigation during those years or portions of the year in which ....low streamflows occur naturally •It if is concluded that navigation i~ ! .... would be adversely impacted,a more detailed study could be conducted in 1982 with the intention of defining,in detail,the extent to which this would occur. For the purpose of this study,navigation is defined as past and present use of the river system for transportation by boats and float planes between May 1 and October 31.Future navigational craft are considered to require a depth similar to that required by the present craft.It has also been assumed that postproject channel morphology would remain much as it is now.The scientific basis for this assumption is found in concluding statements of the river morphology report (R&M Consultants, Inc.1982).The effect of these dams on navigation over ice and snow is not discussed in this document,nor are potential impacts on navigation in Cook Inlet. -3- Some consider 1.5 feet tq be an adequate depth for navigation (R. Krogseng,pers.comm.).However,much of the cross-sectional data used in preparing this report was obtained for purposes other than evaluating project effects on navigation.Hence they may not have been located in the most critical stream reach for determining navigation.In addition, the accuracy of the predicted water surface profiles currently available for the river segment between Devil Canyon and Talkeetna is,at best, approximately one foot (S.Bredthauer,pers.comm.).Because of these considerations,it has been recommended that it would be more appropriate to use a 2.5-foot depth criteria than a lo5-foot depth criteria in this preliminary assessment of potential navigational problems (W.Trihey,pers.comm.) •Both the 1.5-foot and the more conservative 2.5-foot depth criteria are used in this report.Potential navigational problems upstream and downstream of Talkeetna are discussed separately. -4- - - ~, DISCUSSION Site Selection,Data Collection and Data Analysis - Upstream of Talkeetna During the fall of 1980,R&M Consultants,Inc.(R&M)surveyed 66 cross sections for the 50-mile river segment between the confluence of the Susitna and Chulitna Rivers and Devil Canyon.The U.S.Army Corps of Engineers Hydrologic Engineering Center's HEC-2 computer program ("Water Surface Profiles")was used by R&M to forecast water surface profiles for the Susitna River above Talkeetna.Water surface elevations were predicted for six different flow rates at each of the 66 cross sections. This information,along with a description of its development,is presented in the Susitna River Hydroelectric Feasibility Report, Appendix B.7,Hydraulic and Ice Studies.Figure 1 presents a cross- sectional profile and simulated water surface elevations for cross section 32.This is located at River Mile 129.7,about 1.1 river miles ,"- below Sherman.Water surface profiles for calibrating the hydraulic .- model were collected from six crest gage stations in the 50-mile reach of the river.~ue to their limited number,and the distance between the crest gages,possible inaccuracies in the HEC-2 analysis are worth noting.A comparison of stage-discharge data used by R&M in this analysis and that collected by the Alaska Department of Fish and Game (ADF&G)indicates that some errors may exist in the HEC-2 analysis.Mr. Steve ~redthauer of R&M believes the HEC-2 analysis predicts the water -5- surface elevations to within ±1 foot.This should be considered when deciding whether the 1.5-foot or the 2.5-foot depth criteria is most appropriate. Table 1 gives the information used to plot the stage-discharge rating curve for cross section 32.This curve is shown in Figure 2.From this curve,the discharge r~quired to maintain a certain water depth can be determined.For cross section 32,the discharge required to maintain a 2.5-foot depth is 6,500 cfs (Figure 2). Table 1 Cross Section 32 Stage-Discharge Data Thalweg Elevation =602.0 feet Water Depth Surface of Elevation Flow Discharge (feet)(feet)(cfs) 605.2 3.2 9,700 606.0 4.0 13 ,400 606.7 4.7 17,000 607.8 5.8 23,400 608.9 6.9 34,500 610.8 8.8 52,000 Figure 3.5 was developed by R&M.This shows monthly preproject and postproj ect flow duration curves for the Susitna River at Gold Creek. -6- ..... - - .... This information,along with a description of its development and reliability,is given in the Susitna River Hydroelectric Feasibility Report,Appendix B.9,River Morphology. Several operational schedules for water releases past the Devil Canyon dam have been proposed;two are considered in this analysis.Post- project Case A is a water release recommended for maximum power pro- duction.Postproject Case D is a water release recommended for minimal impact on fisheries.Comparing the discharge required to maintain a lo5-foot or 2.5-foot depth to the flow duration curves in Figure 3.5 allows an estimate to be made,for each month of interest,as to the percentage of time existing navigational patterns might be adversely impacted by the two proposed postproj ect development scenarios.This information is shown in Table 2 using the 2.5-foot depth criteria for cross section 32. This same analysis was done for each of the 66 cross sections available for the Devil Canyon to Talkeetna reach.With the exception of cross section 32,this analysis indicates that all locations are navigable both before and after the project,using the 2.5-foot depth criteria. This analysis also indicates that cross section 32 is navigable both before and after the project using the 1.5-foot depth criteria.How- ever,when using the 2.5-foot depth criteria,negativ.e postproject impacts on navigation occur at cross section 32 during June,July, August and September (Table 2).A minimum flow of 6,500 cfs is required -7- to eliminate these negative impacts.Cross section 32 is located at .... River Mile 129.7,about 1.1 river miles below Sherman. Table 2 Cross Section 32 Percent of time the discharge,required to maintain a 2.5-foot depth of flow,is equaled or exceeded. Discharge to maintain Discharge to maintain 2.5-foot 2.5-foot depth of flow (6,500 cfs)depth of flow (6,500 cfs) May August Preproject 90 Preproject 100 Postproject Postproject Case A 100 Case A 70 Postproject Postproject Case D 90 Case D 100 June September Preproject 100 Preproject 97 Postproject Postproject Case A 100 Case A 44 Postproject Postproj ect Case D 90 Case D 97 July October Preproject 100 Preproject 26 Postproject Postproject Case A 97 Case A 100 Pos tproj ect Postproject Case D 100 Case D 65 Summary and Conclusions -Upstream of Talkeetna With the exception of a section of the river below Sherman,this analysis indicates the operation of the dams would not change mainstem navigability of the Susitna River between the confluence of the Susitna - ..... ..... - - and Chulitna Rivers and Devil Canyon. -8- Assuming the 1.5-foot depth - criteria is adequate,navigability of the river near Sherman would not be altered.Using the 2.5-foot depth criteria,navigation near Sherman would be hindered about ten percent of the time,or about one year out of 10 during June under Case Dpostproject flows (minimal fisheries impact).Table 2 also indicates that navigation would be hindered about 30 percent of the time,or about one year out of three in August,and about 53 percent of the time,or about one year out of two in September, under Case A postproject flows (maximum power generation). On February 25,1982,Mr.Steve Mahay,who operates the Talkeetna River Boat Service,was contacted by telephone.He has operated boats on the Susitna River for a number of years.Although Mr.Mahay has never found the reach about one mile downstream of Sherman to be non-navigable under natural flows,he confirmed that,between Talkeetna and Devil Canyon,it is probably the most subject to navigational difficulties due to decreased flow. A review of aerial photographs indicates that these navigational problems may occur not only at this one location,but in a reach of the river about one to three miles below Sherman.Because of the limited data available at this time,this cannot be confirmed or denied.Hence, additional study in this reach is warranted during Phase II. Site Selection -Downstream of Talkeetna To determine if navigational use would be adversely affected by the operation of the proposed dams,aerial photographs and topographic maps -9- of the river were reviewed.Also,discussions were held with persons familiar with navigation in the areas of interest.This resulted in the following areas being designated as those receiving a significant amount of navigational use that could be adversely affected by reduced dis- charges in the Susitna River downstream of the proposed dams. 1.A braided area on the east side of the Susitna River,about six river miles downstream from Talkeetna.This is at about River Mile 91. 2.A braided area on the east side of the Susitna River,adjacent to and extending about one mile downstream of Kashwitna.This is at about River Mile 60 to 61. 3.The Susitna River near its confluence with Willow Creek.This is at about River Mile 48 to 49. - ..... - - ..... 4.On Alexander Slough (also known as the west channel),just as it divides off the mainstem of the Susitna River (also known as the east channel downstream of this point).This is near River Mile 19. Data Collection -Downstream of Talkeetna - Seven staff gages were placed at the sites of interest,two on the Susitna River near Talkeetna,two near Kashwitna Landing,two near Willow Creek,and one on Alexander Slough.Since one gage was placed on -10- .." - .... .... - .... .... a side channel near Talkeetna that receives little traffic,it is not considered further in this report.The staff gages were installed September 22-25,1981.When each staff gage was installed,a survey was made to define the cross section of the stream channel at the gage site and to establish the relative distance between the stream bed and the staff gage readings.The water surface elevation relative to the staff gage was noted when the gage was installed.Several other readings were made during September and October.These cross sections and water surface elevations are shown in Figures 4 through 9. Data Analysis -Downstream of Talkeetna This study will compare t"he depth of flow at the staff gage sites near Talkeetna,Kashwitna Landing,and Willow Creek to the mean daily flow rate in the Susitna River at Sunshine.Unfortunately,the U.S. Geological Survey (USGS)gage recording the Susitna River flow rate at Sunshine became inoperable on September 15,1981.Therefore,the flow rates at this location had to be estimated.This was done by Mr.Jack McKechnie of USGS on February 1,1982.USGS has gaging stations on the Susitna River at Susitna Station,Yentna River near its confluence with the Susitna River,Willow Creek near Willow,and Deshka River near Willow.The Susitna River discharge at Sunshine was taken to equal the Susitna River discharge at Susitna Station minus the discharge from the three gaged tributaries mentioned above,minus a minor amount from ungaged tributaries.Mr.McKechnie believes the Susitna River discharge at Sunshine estimated in this fashion has an accuracy of about eight percent.It is these flow rates,estimated by Mr.McKechnie,that were -11- compared to the depths of flow at the staff gage sites.This infor- mation is shown in Table 3. This study will also compare the depth of flow at the staff gage site located on Alexander Slough to the mean daily flow rate in the Susitna River at Susitna Station,as recorded by the USGS gage 15294350.This information is shown in Table 3. Preliminary rating curves at each of these staff gage sites are shown in Figures 10 through 14.Since there was only one observation of the staff gage on Alexander Slough,no discharge rating curve at this location could be made.From Figures 10 through 14.the discharge required in the Susitna River at Sunshine to maintain a water depth of 1.5-feet or 2.5-feet at the cross sections under study can be deter- mined.These discharges are given in Tables 4 and 5. ..., - - - Figure 3.7 was prepared by R&M.This shows monthly preproj ect and - postproject flow duration curves for the Susitna River at Sunshine. Comparing the discharges given in Tables 4 and 5 to the curves in Figure 3.7 allows an estimate to be made,for each month of interest,as to the percentage of time preproject navigation would be adversely impacted by two proposed postproject conditions at the locations of interest.As mentioned earlier,postproject Case A is a water release recommended for maximum power production and postproj ect Case D is a water release recommended for minimal impact on fisheries.The results are shown in Tables 4 and 5.Table 4 deals with the case when a 1.5-foot depth is considered adequate for navig~tion.Table 5 deals with the case when a 2.5-foot depth is considered adequate. -12- - - .- -13- .... ~, Table 4 Downstream of Talkeetna Percent of time Susitna River discharge at Sunshine,required to maintain a 1.5-foot depth of flow,is equaled or exceeded.""'" Near -, Willow Kashwitna Kashwitna Near Creek Near Landing Landing Willow Middle Talkeetna Upstream Downstream Creek Channel LRX-TKAI LRX-KTA2 LRX-KTA3 LRX-WLDI LRX-WLD3 Discharge for 1.5-foot depths (ds)100 2,750 3,550 10,400 6,500 ~ May Preproject 100 100 100 93 100 Postproject -Case A 100 100 100 100 100 Postproject Case D 100 100 100 99 100 June Preproject 100 100 100 100 100 Postproject Case A 100 100 100 100 100 Postproject Case D 100 100 100 '100 100 July- Preproject 100 100 100 100 100 Postproject Case A 100 1.00 100 100 100 !""IIPostproject Case D 100 100 100 100 100 August Preproject 100 100 100 100 100 Postproject Case A 100 100 100 100 100 Postproject ~ Case D 100 100 100 100 100 September Preproject 100 100 100 100 100 ~ Postproject Case A 100 100 100 100 100 Postproject Case D 100 100 100 100 100 October Preproject 100 100 100 91 100 Postproject ~ Case A 100 100 100 100 100 Postproject Case D 100 100 100 100 100 ~ -14- Table S Downstream of Talkeetna Percent of time Susitna River discharge at Sunshine,required to maintain a 2.S-foot depth of flow,is equaled or exceeded. Near-Willow Kashwitna Kashwitna Near Creek Near Landing Landing Willow Middle Talkeetna Upstream Downstream Creek Channel LRX-TKA1 LRX-KTA2 LRX-KTA3 LRX-WLD1 LRX-WLD3 Discharge for 2.5-foot depths (cfs)100 7,200 8,100 16,200 11 ,000 May Preproject 100 100 99 88 92 Postproject Case A 100 100 100 90 100 Postproject Case D 100 100 100 82 98 June Preproject 100 100 100 100 100 Postproject Case A 100 100 100 100 100 Postproj ect Case D 100 100 100 100 100-:July Preproject 100 100 100 100 100 Postproject Case A 100 100 100 100 100 (P:~Postproject Case D 100 100 100 100 100 August .-Preproject 100 100 100 100 100 Postproject Case A 100 100 100 100 100 Postproject Case D 100 100 100 100 100 September Preproject 100 100 100 98 100 Postproject Case A 100 100 100 96 100 Postproject ,....Case D 100 100 100 98 100 October Preproject 100 100 99 18 87 ,...,Postproject Case A 100 100 100 38 100 Postproj ect Case D 100 100 100 28 100 -15- Summary and Conclusions -Downstream of Talkeetna Although the stage-discharge data at the sites studied are limited,this analysis indicates that operation of the dams will have no negative impacts on navigation in the main channel below Talkeetna or on two access sites near Kashwitna Landing.Using the 1.5-foot depth criteria for navigation,no negative impacts would occur near Willow Creek. Figure 18 indicates that,using the 2.5-foot depth criteria,there would be minor negative impacts here in May with postproject flow Case D. These are predicted to occur roughly six percent of the time,or about two years out of the 30 years of simulated record.Eliminating these negative impacts would require a flow in the Susitna River at Sunshine of 16,200 cfs.During the months of June through September,this access channel to Willow Creek should be navigable,with no significant nega- tive impacts from the dams.Data are insufficient to completely define the flow required at Susitna Station in order to keep the upstream access to Alexander Slough open.It is anticipated,however,that the decrease in stage at this location would be less than one foot for both postproject flows. According to R&M,the Susitna River,upstream of its confluence with the Chulitna River,contributes an average of 43 percent to the Susitna River flow at Talkeetna,and only 19 percent to the flow at Susitna Station.This may help explain why the operation of the dam has such a minor effect on navigation downstream of Talkeetna. -16- - - ~I;:1~-.cQ,w=Q,...II·I'-~~---,---i-----.--L.-__..._II _.'.... 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Note:Elevations Are Based On Arbitrary Datums ~'l" 'I , /•.... ?JtJ ./"'"...,,;'\i\~I I /''tI ~~ z'\/8..1t Cage. 0 , H , E-l /'/f( ~ M 'b~W.8.#',I,I, \, ,J \,/..---/' ?>O '/''.; ~ ~ '\0 0 00 00 00 00 00 00 flJO ~()~...~II,;•~~~.•~....~...~. . .. PREPARED BY I STATION PREPARED FOR' £Fl~&;J1Ml FIGURE 7. RIM CONSULTANTS,INC. !i ]J-1 I 1 J J ]J 1 i 1 J )D .-------------1 SUSJTNA HYDROELECTRIC PROJECT CROSS-SECTION WLO-3 Note:Elevations t Are Based On Arbitrar~ Datums ''btJ r 6 H itj~"llc 'b0 ~8t.1t ' 6881\,---1......'I ,II:,~I I ,....""/I I~w.e.,""'''1-w.s~J 'b/' \ .,,W.8.I,"',, ,l '1 \ /'/" \I,I \ V,',I \,/ .../' '\~0 CbO •• I •II • 00~o &&•II I 00 ~... •.II II Ii II 00~'l,:00~ I -I ~I l~~~O,II I I I !~~~O,,.,.I PREPARED BY I STATION PREPARED FOR' FIGURE 8. J 1 1 ]1 J )I )1 )I J J j 1 ; Note:Elevations Are Based On Arbitrary Datums PREPARED BY' SUSITNA HYDROELEC·TRIC PROJECT CROSS-SECTION ALEX l- I- I- o !~ Staff (jaG-"17 r ....,f-V'"{' .."\/J I j I 1 '.---......\I I 'o .............r",,',,'\I I Il<",....,_j i A 1/\1:~I \! \.i............/........../V \I.s.~,I ,J ;~$,I I-,"H T-i •• \,I .:\I'\r .... v'V"\I,,~\ \ I l'~ ~'\0 I- o 000 00 00 00 00 00 00 ".'\\~...~o .,?~.l~~.....~~..~~.II • STATION PREPARED FOR' FIGURE 9. ])1 ]J ::!=t=t:.....-..::r:--1:+ &_- 4 __flit:fm --~::E:f=t:±::l=,":~. __m.'.flU 30_ 1111I11I1 I1111I1I11IJ+Ht 20_J TIll 1 1111111111111111111111111111111111111111111I11111111 ~ ~3:m1'~.::.•~;~•• tm~t-1ttt11tllnmltn... I-I I ,'-I'~- ..iJillIlmUinID ~-I-H-+I 1 I I I H-HH-I,"- 10_ 9_ 8_ 7_ mit ~'...............In_om, I HH+HHH-lHlHIHHHII .J' ti- Imlffifl=mm+ [I;i 5_ o -ILa..4_ La.. o 3_ :I:,.... a. LLIo 2_1 1 1 1 1 1 11 II 11II III II II 1111 III II 1I11J.U1111 I I"II""II"itti- .\~~7 A '9 PREPARED FOR' FIGUREIO. ~6 1 8 ~100,0002~A 5 01 SCHARGE.cfs I •I Ii' 5 6 7 8 9 10,000I 4 STAGE -DISCHARGE RATING CURVE SUSITNA RIVER AT LRX-TKAI (NEAR TALKEETNA) (AFTER ORIGI'NAL CURVE BYADNR) •3 L-l ' , , ,""'1 """"'111I1""'111I111/1'1""1""1""111I11"111 , , , ,""'1"11""'1""""'1' 1 000 2 PREPARED'BV' f~I&rMI; RaM CONSULT~NTS.INC. j .~J .1 ])-)) ----:--•I- 5_-•rr ,1-1:• -,.=: -~-..: 4 ..---_. --o 1·-... ~=:'"":::I- 3O...-.:_...-f-':"I=~:.:::·. 1-'.......• 0 •. .-.....-... ~o 0 ,UUll»- I -~-.!-.--I-0_.,, l-I·..' 20_ .'0 ... f---l-i--1-.....'..'...-~-~~-'.... -.........'.,,,..,....' ---I--.-·. ..0 ,. -. 10_§!II 4H;t..__'lllf .0gEE .,.'...-. I--'" 8_ 0' o 1--. 7_ ..: ~6_ ~5_r==~ .,.I0==1==..J ===E=f+HttItI-~~4_MUI LL 0 ~-::t: ~ t----c- .0- W 02_~um I , 0 L --?•I I • • I • I I .\•I I I I ~!I 5 A +8 '~9 ~ 1000 3 4 5 6 7 8 9 10 ,000 2 3 5 6 7 8 9 100,000 4 PREPARED'BY'i DISCHARGE.cfs PREPARED FORI VC~M STAGE -DISCHARGE RATING CURVE H[i]lir-lt .,,~.";0...,"o~;;.::SUSITNA RIVER AT LRX-KTA2~:::~~..:::,':::.•,..'~...?:-:.~:.::':.:.~:.''.::::;~':: RaM CONSULTANTS,INC.(KASHWITNA LANDING UPSTREAM) (AFTER ORt G't NAL CURVE BY ADNR)FIGURE .'. )1 -))» -rtiE-ffil'mIltTtTH'I'(II (I . 5 __ ..=:- ~'---10--I- 4._ -_.: -::;;::.-..•....~: ~=:::::~=•.I-.-1- 30_~=...:.:f:::~_.':.:'-f-.-l-.....-." ........ rH+Htt-;::::.. -~-.~... ~-- 20_ ........ .... •I··......-,-1--....i--... ..... .-1--....i--....... -l-................. ......-I-.'..,. .'.... to.:mtm:-iffilUf ..mumf ..::'...": 9_ 8_ ..._.: 7. : ,..: .. u..6 ....1--r ... 3:5_III ,-I • 0 •-oJ lL 4_mmt:~H' lL o 3_ X....a..w >UHH- o 2_ I .mmu '-2 I I I .I I I I I I .\'I I ~'~!~I ~~8 ':9 I 1000 3 4 5 6 7 8 9 10,000 2 3 5 .67 8 ..100,000 5 PREPARED'BY',.DISCHARGE.cfs PREPARED FORI ~Mi STAGE-DISCHARGE RATING CURVE 12 fii]~f~.}IMl SUSITNA RIVER AT LRX-KTA3 Rail CONSULTANTS, INC.(KASHWITNA LANDING DOWNSTREAM) (AFTER ORIG'INAL CURVE BY ADNR).FIGURE I J I 11s J J J --I ~-I--I5__n I .."...'*I+f: mtt __:L-!.. t:tmtl .:::t::±::l-: 4 __.-::.-... -:1- -r.~I;;:~:... ~=I=.~=.::'~I:' 30_ ~~=..•+.-..:~:~~t::~....".. ..~.....,._4 ......."..- ~-.... t=1-1-- ,"",uu·~-'r--~'I-'-...r-. -!--t-.~-I- 20_ ..... --. . ...... -....~....".........-.........,....."".-." -... .-.. .. 10_..:mut .~.,. 9_WJ II·IH:H:l!.. 8_ o. .>=-~.. 7_ : ~6_. ~5_~It I0 ...J 4_.....flmH- LLo 3_ :J:.- Q..~ LUo 2_ I I l fUmm I- ~I I I I , , I I I 4 I 6 t 1:1 ~00,000 ~!I ,~+8 ':9 i 1000 3 4 5 6.7 ~9 10,000 2 3 5 4 5 PREPARED'BY",DISCH ARGE'"cfs PREPARED FOR' ~13iiJ~~Ci;-,M STAGE -DISCHARGE RATING CURVE SUSITNA RIVER AT LRX -WLO I RIM CON $UlTANTS.INC.(NEAR WILLOW CREEK) (AFTER ORIGINAL CURVE BY ADNR)FIGURE .. j J )»] --I 1-.•I5__. .:u.~-.1="-.:_..-.... 4 __:-...-t-: ...:.. ~=p=:~=::.:::.. ~O..-1--•:.f:.:'.:::.-:>-~---.........:IUtU ... :~~+......... f.-_... t=~.f......1-.-......... 20_..... ~--i-J-o.-...,........., l-I-f-'~f-I--.,..-...~.........-..... ....,. 10.i::Uttm II ~., 9_ ...~...... 8_._-.. 7_ it 6. ~5_•1 m0 ~4_ lI- o 3_ J: l-n.. IJJo 2.I I-HHH- I L ~I I I I I I I I I .\I 6 ~~~OOJOOO ~!I I ~1 8'9 I1000.3 4 5 6 1 8 9 IOJ OOO 2 3 5 4 5 PREPARED BY'-,.DISCHARGE.cfs PREPARED FORI --~STAGE-DISCHARGE RATING CURVE 14 [Ii~lf~1M SUSITNA RIVER ATLRX -W LO:3 RIM CONSULTANTS,INC.(NEAR WILLOW CREEK.MI DOLE CHANNEL) (AFTER ORIGINAL CURVE BY ADNR)FIGURE . 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