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HomeMy WebLinkAboutAPA2600/.~ VOLUME I -MAIN REPORT Final Report February 1985 Document No.2600 CASE E-YI ALTERNATIVE F·LOW REGIME LJa.IARI N..A!Jl(A DEPJ··OF FISH ..8AME 3S~Rt:t£Pbet.".r<'d. ~Alei",ml"l!ai'9 ALASKA POWER AUTHORITY ____ [R1~~=[g~~®©@ TNA JOINT VENTURE FEDERAL ENERGY REGULATORY COMMISSION PROJECT No.7114 SUSITNA HYDROELECTRIC PROJECT ·A">""'\ '....L.,....i.'..,....."l.,f1J\'U·V - ""'", i .... - .... ,. Document No.2600 Susitna File No.6.18.7.5 II" ILfa5 .SS Flr1~ V\D I ;l t.o 00 SUSITNA HYDROELECTRIC PROJECT CASE E-VI ALTERNATIVE FLOW REGIME VOLUME 1 MAIN REPORT Report By Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Final Report February 1985 ARLIS Alaska Resources Library &Information Services Anc 1"rOl:v Yc Alaska•••W'O ' - ..... - - - - TABLE OF CONTENTS Se!ction/Tit1e 1.0 INTRODUCTION 2.0 DEVELOPMENT OF ALTERNATIVE ENVIRONMENTAL FLOW CASES 2.1 BACKGROUND 2.2 SELECTION CRITERIA 2.2.1 Management Objectives 2.2.2 Critical Species and Habitat Combinations 2.2.3 Compatibility with Mitigation Policy 2.3 CHARACTERISTICS OF THE ALTERNATIVE ENVIRONMENTAL FLOW CASES 3.I)SELECTION OF FLOW CASE E-VI 3.1 FLOW CONSTRAINTS 3.1.1 Flow Stability Constraints 3.1.2 Dam Safety Criteria 3.1.3 Emergency Situations 3.2 POWER AND ENERGY CONSIDERATIONS 3.2.1 Reservoir Operations Program 3.2.2 Watana Operation -1996 and 2001 3.2.3 Watana and Devil Canyon Operation -2002 and 2020 3.3 PROJECT FLOWS AND RESERVOIR OPERATIONS 3.3.1 Watana Operation -1996 and 2001 3.3.2 Watana and Devil Canyon Operation -2002 and 2020 1-1 2-1 2-3 2-4 2-5 2-16 2-17 3-1 3-3 3-6 3-10 3-11 3-11 3-14 3-15 3-16 3-16 3-21 69274/TOC 850219 i ..... TABLE OF CONTENTS (cont'd) Section/Title 3.4 WATER QUALITY--3.4.1 Watana Operating Alone 3.4.2 Watana and Devil Canyon Operating .....3.4.3 Refinement to Reservoir and River Temperature and Ice Studies 3.5 IMPACT ASSESSMENT 3.5.1 Life Stage Impacts -Pacific Salmon..... 3.5.2 Life Stage Impacts -Resident Evaluation Species .....3.6 MITIGATION 4.0 FLOW REQUIREMENTS DURING DAM CONSTRUCTION AND RESERVOIR IMPOUNDMENT 4.1 WATANA 4.2 DEVIL CANYON 5.()REFERENCES .... 3-27 3-28 3-31 3-37 3-41 3-41 3-44 3-47 4-1 4-7 5-1 69274/TOC 850219 ii - .... Appendix A Appendix B AppendixC Appendix D Appendix E Appendix F Appendix G Appendix H Appendix I 69274/TOC 850219 APPENDICES Resource Agency Meeting Minutes -November 1984 and December 1984. Resource Agency Comments on 'Evaluation of Alternative Flow Requirements',(Harza-Ehasco November 1984). Status of License Application Figures and Tables Related to Case E-VI. Stream Flow Time Series,Sus itna River at Watana and Devil Canyon,(Harza-Ebasco 1985). Stream Flows and Flow Duration Curves at Watana,Gold Creek, Sunshine and Susitna Station -for Watana Only Operation in 1996 and 2001. Stream Flows and Flow Duration Curves at Watana,Devil Canyon,Gold Creek,Sunshine and Susitna Station -for Devil Canyon Operation in 2002 and 2020. Reservoir/River Temperature and Ice Simulations -Watana Only Operating,2001. Reservoir/River Temperature and Ice Simulations -Watana and Devil Canyon Operating,2002. Refinement to Reservoir and River Temperature and Ice Studies for Simulation Period October 1976 to May 1977 • iii Number 2.2-1 LIST OF TABLES.. Title susitna Hydroelectric Project Influence of Mainstem Flow on Primary Parameters of Associated Habitat Types 2-7 Watana Cone Valve Operation,1996 Energy Demands 3-17 Devil Canyon Cone Valve Operation,2002 Energy Demands 3-22 2.2-2 2.2-3 3.1-1 3.3-1 P"'Ul 3.3-2 3 .l~-l .... 3 .~f-2 r- 3.4;-3- ,... 3.4·-4 '"""I I I """[ 69274/TOC I"""850219[ i Susitna Hydroelectric Project,Uses of Susitna River Habitat Types by Evaluation Species Susitna Hydroelectric Project,Primary Utilization of Sensitive Habitat Types by Evaluation Species Susitna Hydroelectric Project,Flow Contraints for Environmental Flow Requirement Case E-VI Susitna Hydroelectric Project,Watana Fixed Cone Valve Operation,1996 Simulation Susitna Hydroelectric Project,Watana Fixed Cone Valve Operation,2001 Simulation Susitna Hydroelectric Project,Devil Canyon Fixed Cone Valve Operation,2002 Simulation Susitna Hydroelectric Project,Devil Canyon Fixed Cone Valve Operation,2020 Simulation 1V 2-10 2-15 3-2 3-32 3-33 3-38 3-39 ..... ..... - - r I 'l - Number 4.1-1 4.1-2 4.1-3 4.1-4 69274/TOC 850219 Title Susitna Hydrolectric Project,E-VI Flow Requirements During Filling of Watana Reservoir Susitna Hydroelectric Project,Pre-Project Streamflow Sequences Used in Filling Simulation Susitna Hydroelectric Project,Susitna River Discharges (cfs)Measured at Watana During Watana Filling,Case E-VI Flow Requirements Susitna Hydroelectric Project,Susitna River Discharges (cfs)Measured at Gold Creek During Watana Filling,Case E-VI Flow Requirements v 4-3 4-4 4-5 4-6 - - - - - .- Number 2.3-1 2.3-2 2.3-3 3.3-1 3.3-2 3.3-3 3.3-4 3.3-5 3.3-6 3.3-7 692:74!TOC 850219 LIST OF FIGURES Title Mitigate with Flow for Chum Salmon Side Slough Spawning Habitat Mitigate with Flow for Chinook Salmon Side Channel Rearing Habitat Mitigate with Flow for Both Chinook Salmon Side Channel Rearing Habi tat and Chum Salmon Side Slough Spawning Habitat Environmental Flow Requirements,Case E-VI,Discharges at Gold Creek,Watana Operation in 1996 Watana Reservoir Surface Elevation,Probability of Occur- rence on October I,Watana Operation,1996 Energy Demands Watana Reservoir Surface Elevation,Probability of Occur- rence on January I,Watana Operation,1996 Energy Demands Watana Reservoir Surface Elevation,Probability of Occur- rence on April I,Watana Operation,1996 Energy Demands Watana Reservoir Surface Elevation,Probability of Occur- rence on July I,Watana Operation,1996 Energy Demands Watana Reservoir Water Levels,Watana Only Operating, 2001 Simulation,Case E-VI Watana Reservoir Inflow VI. 2-19 2-20 2-21 3-49 3-50 3-51 3-52 3-53 3-54 3-55 Number 3.3-8 3.3-9 3.3-10 Title Watana Reservoir Outflow,Single Reservoir Operation, E-VI Load Year 2001 Watana Reservoir Water Surface Elevation,Single Reservoir Operation,E-VI,Load Year 2001 Environmental Flow Requi rements,Cas e E-VI,Discharges at Gold Creek for Watana Operation in 2001 3-56 3-57 3-58 .... 3.:3-11 3.:3-12 3.3-13 3.3-14 3.3-15 3.3-16 3.3-17 69274/TOC 850219 Watana Reservoir Surface Elevat ions;Probabi lity of Occur- rence on October 1,Watana Operation 2001 Energy Demands 3-59 Watana Reservoir Surface Elevations,Probability of Occur- rence on January 1,Watana Operation 2001 Energy Demands 3-60 Watana Reservoir Surface Elevations,Probability of Occur- rence on April 1,Watana Operation,2001 Energy Demands 3-61 Watana Reservoir Surface Elevations,Probability of Occur- rence on July 1,Watana Operation,2001 Energy Demands 3-62 Environmental Flow Requirements,Case E-VI,Discharges at Gold Creek for Watana and Devil Canyon Operation in 2002 3-63 Watana Reservoir Surface Elevations,Probability of Occur- rence on October 1,Watana and Devil Canyon Operation, 2001 Energy Demands 3-64 Watana Reservoir Surface Elevations,Probability of Occur- rence on January 1,Wat?na and Devil Canyon Operation, 2001 Energy,Demands 3-65 vii ..... - ..... Number 3.3-18 3.3-19 3.3-20 3.3-21 3.3-22 3.3-23 3.3-24 3.3-25 3.3-26 3.3-27 69274/TOC 850219 Title Watana Reservoir Surface Eleyations,Probability of Occurrence on April 1,Watana and Devil Canyon Operation,2001 Energy Demands Watana Reservoir Surface Elevations,Probability of Occurrence on July 1,Watana and Devil Canyon Operation, 2001 Energy Demands Watana Reservoir Water Levels,Watana and Devil Canyon Operating,2002 Simulation,Case E-VI Devil Canyon Reservoir Water Levels,Watana and Devil Canyon Operating,2002 Simulation,Case E-VI Environmental Flow Requirements,Case E-VI,Discharges at Gold Creek for Watana and Devil Canyon Operating in 2020 Watana Reservoir Water Levels,Watana and Devil Canyon Operating,2020 Simulation Case E-VI Devil Canyon Reservoir Water Levels Watana and Devil Canyon Operating,2020 Simulation,Case E-VI Watana Reservoir Outflow,Watana and Devil Canyon Operating,E-VI,Load Year 2020 Devil Canyon Reservoir Inflow,Watana and Devil Canyon Operating E-VI,Load Year 2020 Devil Canyon Reservoir Outflow,Watana and Devil Canyon Operating,E-VI,Load Year 2020 viii 3-66 3-67 3-68 3-69 3-70 3-71 3-72 3-73 3-74 3-75 .- - Number 3.3-28 3.3-29 3.3-30 3.:3-31 3.3-32 3.3-33 69274/TOC 850219 Title Watana Reservoir Water Surface Elevation,Watana and Devil Canyon Operating,E-VI,Load Year 2020 Devil Canyon Reservoir Water Level,Watana and Devil Canyon Operating E-VI,Load Year 2020 Watana Reservoir Surface Elevations,Probability of Occurrence on October 1,Watana and Devil Canyon Operation,2020 Energy Demands Watana Reservoir Surface Elevations,Probability of Occurrence on January 1,Watana and Devil Canyon Operation,2020 Energy Demands Watana Reservoir Surface Elevations,Probability of Occurrence on April 1,Watana and Devil Canyon Operation,2020 Energy Demands Watana Reservoir Surface Elevations,Probability of Occurrence on July 1,Watana and Devil Canyon Operation,2020 Energy Demands Susitna River Flows at Gold Creek,Filling of Watana Reservoir,Case E-VI Flow Requirements 3-76 3-77 3-78 3-79 3-80 3-81 4-8 -CASE E-VI ALTERNATIVE FLOW REGIME 1.0 INTRODUCTION On November 2,1984,the Alaska Power Authority submitted a report to the FE!deral Energy Regulatory Commission (FERC)evaluating alternative flow rE!quirements (Harza-Ebasco 1984d).The alternative flow requirements were rE!finements to the Case C flow requirements contained 1.n the Sus itna Hydroelectric Project License Application -Project No.7114 (Alaska Power Authority 1983).The report incorporated results of additional studies and analyses that have been conducted since submittal of the License Application.These study results allowed development of more detailed and rE!fined environmental flow requirements to meet specific environmental m.!:magement objectives.As a result of the evaluation,the Power Authority sE!lected one alternative,Case E-VI,as the preferred flow regime case bE!cause it produced superior energy benefits and no net loss in habitat v~Llue through control of flow releases and other mitigation measures. On December 3,1984,FERC requested that the Power Authority formally file the Case E-VI refinement with the Commission.This report responds to that rE!quest.It provides information on the development of alternative environmental flow cases,but focuses on in format ion specific to Case E-VI. E'or further information on al ternative regimes,the reader is referred to the Evaluation of Alternative Flow Requirements report submitted on November 2,1984 (Harza-Ebasco 1984d). Discussions were held with resource agency personnel on November 20 and 27, 1984 concerning the alternative flow requirements report and the process to be used to arrive 'at an acceptable flow regime.Those meetings are summarized in Appendix A hereto.Further discuss ions were held on December 20,1984 with the regional directors and commissioners of the rE!SOUrce agencies or their representatives.These discussions also focused 42187711 8~j0227 1-1 .... .... .- r on the refined flow regime case and the settlement process.The December 20,1984 minutes are also summarized in Appendix A. Comments on the IlEvaluation of Alternative Flow Requirements"report by v~Lrious resource agenc~es are included as Appendix B.These formal comments convey a positive opinion that an acceptable flow regime is achievable. Where appropriate,specific concerns of the resource agencies are addressed in this document • -42187711 8510227 1-2 ...... '""" ..- -I 2.0 DEVELOPMENT OF ALTERNATIVE ENVIRONMENTAL FLOW CASES 2.1 BACKGROUND The License Application (Exhib.B,Vol.2,pp.B-2-121 through B-2-130) presented ten alternative flow regimes ranging from the regime which would optimize project economics (Case A)to a regime that would approximate pre- pJL"oject average,run-of-river conditions (Case G).Seven of the cases (C, Cl'C2,D,E,F,G)emphasized the use of flow control and planned releases tlJ mitigate potential impacts on downstream aquatic habitats.The major difference among these environmental cases was a gradual,incremental d4~crease of summer minimum flows from Case G through Case A (Lie.App., EJchib.B,Vol.2,Table B54).Emphasis was placed on maintaining higher flows (i.e.smaller incremental decreases)during mid-July to mid-September to mitigate impacts on access conditions into side sloughs for spawning adult salmon (Lie.App.,Exhib.B,Vol.2,pp.B-2-127 and B-2-128). All the flow cases were analyzed to evaluate and compare their economic and environmental consequences.Case C was selected,based on this analysis,as the best compromise between economic and instream flow considerations. Attributes of the flow cases,emphasis on access to sloughs for spawning salmon,evaluation of the consequences of project operation,and mitigation piLanning were based on information available when the License Application was submitted.However,the Power Authority recognized the potential need to refine the selected case and stated in the Application that, "As a more refined assessment of fishery impact,mitigat ion costs and projected project net benefits becomes available,the project operational flow will be adjusted." (Lie.App.,Exhib.B,Vol.2,B-2-130). R,~sults of several studies and other information have become available s~nce the License Application.This accumulated information has provided a more 42187711 850227 2-1 .... dl~tailed and complete understanding of habitat use by the evaluation species and the importance of certain physical processes in the Susitna system as they relate to the quantity and quality of aquatic habitats.The new information is sufficient to refine Case C to more adequately provide for habitat requirements of the eval uat ion spec ies.The primary reasons to r,~fine Case C relate to (1)mainstem and side channel rearing habitats,(2) s.~asonal flow constraints,and (3)maximum flow constraints. .... ,.... I I""" I ..... ..... I""" ! (1)Mainstem and side channel rearing habitats The use of mainstem associated habitats for rearing is more common than previously perceived.Chinook salmon juveniles use side channel habitats for rearing during the summer (ADF&G 1984b).They are found in the side channels in greatest densities when flow is dominated by turbid water overflow from the mainstem..Conditions in the side channels are directly influenced by mainstem discharge at these times. Chum salmon also use turbid water,low velocity,mainstem sites for short-term rearing during their downstream migration to Cook Inlet. The rationale used to establish Case C flow requirements did not include consideration of the use of mainstem and side channel habitats for rearing.The primary environmental considerations in the Case C flows were for upstream migration by adult salmon,access conditions into side sloughs for spawning chum and sockeye salmon,and downstream passage of juvenile salmon during migration to Cook Inlet (Lie.App., Exhib.B,Vol.2,p.B-2-l28). Seasonal flow constraints Environmental flow constraints for the entire year are necessary to maintain overall aquatic habitat values.The minimum flow constraints included in Case C are a composite of environmental and reservoir operating guidelines.Environmental considerations focused on summer 42187711 8~;0227 2-2 .... - (3) flow,and winter mLnLmum flows were based on reserVOLr operations for an extreme dry year (1969).There are important uses of the aquatic habitats throughout the year so there is a parallel need to establish appropriate environmental flow requirements for the entire year,rather than focusing only on the summer flow period. Maximum flow constraints It is now believed that maXLmum flow constraints are needed.The flow cases presented in the License"Application did not include maximum flow constraints.Maximum constraints are not critical during the summer sLnce the project will be storing flows.However,winter maxima can serve to maintain a desired level of flow stability,protect peripheral habitats,and enhance the feasibility of certain mitigation alternatives,such as artificial berms and other structural modifications in side sloughs. "'""I The first step toward refining Case C was to develop a set of alternative flow cases that preserved the basic qualities of Case C while rectifying its deficiencies and incorporating the new.- information.The alternative flow cases also had to meet the selection criteria that are discussed in the next section. 2.2 SELECTION CRITERIA .... Seyeral criteria were established for selection of alternative flow cases. The criteria were: 1.The flow case had to be goal oriented.That is,the case had to be designed to achieve a specified level of habitat quantity and quality <Section 2.2.1}. 2.The flow case had to emphasize critical or sensitive species and habitat combinations <Section 2.2.2). 42187711 2-3 850227 .- 3.The flow case had to be compatible with mitigation policy.That is,it had to focus on evaluation species,emphasize preservation of habitats in a state of natural production,and integrate with other mitigation efforts (Section 2.2.3). 2.2.1 Management Objectives The programming of flow regulation to mitigate for potential downstream pl:'oject impacts requ1res a clear statement of objectives.A particular objective will dictate the quantity and timing of flow releases and set a standard by which the success of flow regulation can be measured. The management objectives chosen by the Power Authority emphasized chum sallmon spawning in side sloughs and chinook salmon rearing in side channels (the reasons for this emphasis are detailed in sections 2.2.2 and 2.2.3 bE!low).The specific objectives were: 1.To maintain quantity and quality of existing habitats (ie.,no net loss in habitat value). .....2•To maximize chinook salmon production (rearing)in existing habitats. 3.To maintain 75%of existing side slough spawning habitat for chum salmon. 4.To maintain 75%of existing side channel rearing habitat for chinook salmon. -5. 42187711 850227 To maintain 75%of existing side slough and side channel habitats for chum salmon spawning and chinook salmon rearing, respectively. 2-4 -6.To maintain 75%of existing side channel rearing habitat for chinook salmon and provide flows (spikes)for access by spawning chum salmon into side sloughs (minimum structural modification of critical reaches for access). ,..., - -I 7.To maintain 75%of existing side channel rearing habitat for chinook rearing and provide flows (spikes)for access by spawning chum salmon into side sloughs by spawning chum salmon (moderate structural modification of critical reaches for access). The Power Authority applied these objectives and developed eight alternative flow cases for evaluation and comparison (Harza-Ebasco 1984d).This process included an analysis of characteristics of habitat types and identification of project-sensitive habitat use by the evaluation species.These factors are detailed below. 2.2.2 Critical Species And Habitat Combinations The primary change from natural riverine condit ions due to project oper- ations will be altered streamflows in the mainstem Susitna River.The project will change the annual hydrology by storing high summer flows for rIE!lease during the normally low flow period in winter.This primary change will also alter annual cycles for factors associated with mainstem flow such as water temperature t turbidity and suspended sediment.These changes will not affect all habitats equally.The magnitude of effect will depend on the l<i:!vel of influence that mainstem conditions have on physical characteristics of the various habitat types.In addition t the habitats are not used uniformly by all species at all times.Therefore,some prioritization is n,ecessary for effective allocation of flows.The timing and volume of flow discharge should be planned to produce the greatest possible mitigative" effect for the aquatic habitats and evaluation speCLes. The Power Authority evaluated habitat characteristics and seasonal habitat uses by the evaluation species in order to develop a rationale for 42187711 850227 2-5 .- ..... - - ..... - ..... ..... establishing environmental flow requirements and to plan project operations. The general approach was to find the most important,based on density, frequency and duration,uses of the aquatic habitats which are most sensitive to mainstem flows.This process and its results were also reviewed to avoid overlooking a critical use of a less sensitive habitat th.at would be adversely impacted by project operation.No such circumstance was found. 2.:2.2.1 Habitat Sensitivity to Mainstem Conditions Ch;anges due to project operation will be greatest in the Middle River reach (D,evil Canyon-Talkeetna;Lie.App.,p.E-3-72).The magnitude of discharge ch.anges in the Middle River will be dampened in the Lower River by the dominating influence of inflow from the Chulitna,Talkeetna and Yentna Rivers (Appendix E and F),especially during spring and summer.Therefore, flow regulation intended to mitigate project impacts will have limited effectiveness for Lower River (Talkeetna-Cook Inlet)habi tats.Other factors associated with mainstem di scharge,such as temperature,turbidity, and suspended sediment,will follow the same trend.The magnitude of change will decrease with distance downstream from the project site (AEIDC 1984b) and the effect of any design or operational measures to mitigate these changes will be "masked"by the influence of inflow from the major tributaries.Therefore,the current analysis focuses on evaluation species and habitats found in the Middle River • Seven habitat types have been defined 1n the Middle River Basin (AEIDC 1984a).Each was characterized and compared based on the level of influence mainstem conditions have on particular physical attributes of the habitats (Table 2.2-1). 42187711 850227 2-6 Table 2.2-1 :- SUSITNA HYDROELECTRIC PROJECT INFLUENCE OF MAINSTEM FLOW AND WATER QUALITY ON ,.- CHARACTERISTICS OF AQUATIC HABITAT TYPES i""" Physical Characteristics-Habitat Type Hydraulicll Hydrologic Temp.Turbidity Ice Total -Mainstem (MS)4 4 4 4 4 20 Side Channel (SC)3 4 4 3 4 18- Tributary Mouth (TM)3 3 2 2 3 13 ~ Side Slough (SS)2 2 2 2 2 10-I Upland Slough (US)1 1 0 0 0 2 I""" Tributary (T)0 0 0 0 0 0 Lake (L)0 0 0 0 0 0 o no influence 1 .-small.limited influence 2 .-moderate,occasional influence 3 .-moderate.frequent influence 4 .-direct.extensive influence ...... 11 Depth,velocity.wetted area,etc. 42187711 850227 2-7 .... .... -I ..... Tributary and lake habitat types are isolated from mainstem influence and their physical attributes will not be effected by project operation.Upland sloughs are usually in old overflow channels and oxbows that are presently iso1at.ed from the mainstem.They receive ma instem water only during infrequent and high flood events.Mainstem influence is limited to small backwater areas at the slough mouths so project operation will have little effect on upland slough habitats. Side channels and side sloughs are active overflow channels that differ primarily in the frequency of receiving mainstem flow.Side sloughs are the most lateral channels and receive mainstem flow less often than side channels.Habitat characteristics of the side sloughs are controlled by local climate,runoff and groundwater upwelling during periods of relative isolation from the mainstem.Side channels are more closely associated with the mainstem and some receive mainstem flows through most of the year.Side channels may completely dewater during periods of low mainstem flow or,if groundwater or intragrave1 flow is sufficient,their habitat characteristics may resemble side sloughs.Both side channel and side slough habitat types are influenced by mainstem flows and several of their physical habitat components are sensitive to changes in mainstem discharge. Tributary mouth habitat is the area bounded by the uppermost point of mainstem induced backwater effect 1n a tributary and the area of clearwater plume from tributary flow into the mainstem.The areal extent and physical attributes of this habitat type are controlled by both mainstem and tributary conditions. The relative influence of mainstem flow on pr1mary characteristics of the major habitat types is summarized in Table 2.2-1.This summary shows that mainstem,side channel,side slough and tributary mouth habitat types are influenced by the mainstem and several of their physical attributes are se:nsitive to change in mainstem discharge • .....42187711 85i0227 2-8 -, '""" - - - .... """' - 2.2.2.2 Habitat Use By The Evaluation Species The next step in this analysis was to evaluate use of the habitat types by each of the evaluation species (Table 2.2-2).The information used for this step is contained in ADF&G,1984a and 1984b.Lake habitat was not included due to its isolat ion from mainstem influence.Tributary habi tat,although isolated from mainstem influence,was included because of its dominating role in overall production in the Middle River for most evaluation species. Habitat use by each evaluation species was separated into major life history and behavioral components:migration,spawning/incubation and rearing. Migration includes both directed movement to particular sites,such as the upstream migration of adult salmon to spawning sites,and more non-directed activity,such as movement by rearing fish from one habitat site to another. Sp,awning and incubation were combined because they are limited to the same haM tat sites and although their specific habitat criteria (needs)may differ,each limits the habitat flexibility of the other.Rearing 1S used broadly in this analysis to include the relatively active"period of feeding and rapid growth during the summer and the less active overwintering period. Th,e habitat uses noted 1n Table 2.2-2 are the most important or predominant for each species.For example,chinook salmon juveniles are found in upland sl()ugh and tributary mouth habitats.However,their use of these habitats for rearing is much less important than use of side channel,side slough and tributary sites. Chinook Salmon Most of the upstream migrant adult chinook enter the Middle River from mid-, June to mid-July.They pass th.rough mainstem and tributary mouth habitats to their natal tributary streams to spawn from late July to mid-August.All chinook spawning and incubation occurs in the tributaries. 42187711 850227 2-9 ....., Table 2.2-2 -SUSITNA HYDROELECTRIC PROJECT, USES OF SUSITNA RIVER HABITAT TYPES BY EVALUATION SPECIES E:valuation Species Habitat Type MS SC TM SS US T Chinook Salmon Migrate X X X Spa:wn-incubate X Rea.r X X X Coho Salmon Migrate X X X Spa.wn-incubate X Rear X X Chum Salmon Migrate X X X X X Spa.wn-incubate X X X Rear X X X Sockeye·Salmon Migrate X X Spa.wn-incubate X Rear X X piIlLk Salmon Migrate X X XrSpalwn-incubate X Rear Arctic Grayling Migrate X X X Spalwn-incubate X Rea.r X X X Rainbow Trout Migrate X X X Spalwn-incubate X I"""Rea,.r X X X Burbot Migrate X Spalwu-incubate X Realr X Dolly Varden Migrate X X X S palwn-incubate X Real.r X X """ 422:501/TBL 850204 2-10 - - .... I - ,... Juvenile chinook salmon (age 0+)begin rearing 1.n their natal tributaries immediately after emergence.This early rearing during May and June is limited almost entirely to tributary sites.Beginning in late June,there is a gradual redistribution of large numbers of juveniles from tributary to side channel and side slough habitats.The major rearing sites during July and August are in tributaries and side channels.The juvenile chinook rearing in side channels begin moving into side sloughs in September and by November,the greatest densitites are found in tributaries and side sloughs, which are the major overwintering habitats.The juvenile chinook (age 1+) move out of their overwintering habitats and migrate to Cook Inlet during the spring and early summer.Downstream migrant chinook are out of the Middle River by mid-July. Coho Salmon Adult coho salmon migrate into the Middle River from early AUgQst to early September to spawn.Essentially all coho spawning and incubation occurs in tributary habitat sites from late August to early October.Coho juveniles begin rearing in natal tributary habitats immediately after emergence.Many of the juveniles leave the tributaries and redistribute into upland sloughs and side sloughs during late June and early July.The major rearing habitats during July to October are tributari.es and upland sloughs.Data regarding overwintering sites suggest that upland sloughs are most important. Chum Salmon Adult chum salmon enter the Middle River from mid-July to early September. Most spawn in either tributary or side slough habitats and a few spawn in side channe,ls with suitable upwelling condi t ions.Major spawning occurs from mid-August through September.Chum salmon juveniles begin rearing 1.n their natal habitats after emergence in the spring.They tend to remain in these sites until they begin a gradual downstream migration to Cook Inlet in June.Juvenile chum will use low velocity,backwater areas in the mainstem 42187711 850227 2-11 .- ,.,.. - - -! fOlr holding and.perhaps.some short term rear1ng during downstream migration.The chum salmon juveniles move out of the Middle River by mid- July. So(~keye Salmon Adult sockeye salmon (second run)move into the Middle River from mid-July through August.They spawn.almost exclusively.in side sloughs from mid- August to early October.Sockeye juveniles begin rearing in their natal side sloughs after emergence in late spring.They are most abundant in side sloughs during May and June and begin moving into upland sloughs in late June.They are most abundant in upland sloughs from July through mid- September.Their densities in the Middle River decline abruptly in all habitats by mid-August.Most of the juveniles apparently move out of the Middle River at this time and the few that remain overwinter in side slc)Ughs. Pink Salmon Adult pink salmon migrate into the Middle River from mid-July to mid-August and spawn almost exclusively in tributaries.Pink salmon juveniles begin migrating downstream after emergence and are out of the Middle River by late June. Arctic Grayling Arctic grayling are most commonly associated with clearwater habitats. S~twning and major summer reari~g occur in tributaries.They also rear in tributary mouth habitat.Some grayling move out of the tributaries into mainst em areas in lat e summer.Overwintering occurs in both t ribut ary and mainstem habitats. 42187711 850227 2-12 - ..... ..... R~Linbow Trout Ratinbow trout are associated with clearwater habitats.Spawning and major rE!aring occur in tributary habitat.Some rainbow congregate at tributary mouths during late summer.This behavior appears to be in response to food supply (salmon eggs)provided by spawning salmon.Rainbow trout move out of the tributaries to tributary mouths during late summer and early fall and overwinter in the mainstem. Btlrbot Btlrbot are,found in the mainstem throughout the year.They occur mostly in turbid,low velocity,backwater areas directly influenced by mainstem flow. Spawning occurs during January.Although specific spawning sites in the Middle River have not been found,evidence suggests they spawn at slough mouths and in deep,backwater areas influenced by groundwater. Dolly Varden The majority of spawn1ng and rearing by Dolly Varden occurs 1n tributary habitat.They move from the mainstem into tributaries by late June.The Dolly Varden move back out of the tributaries in late fall and overwinter in the mainstem. Conclusions Regarding Habitat Use Several general observations can be drawn from the habitat uses summarized in Table 2.2-2.First,tributary habitat is the habitat type used most commonly by the evaluation species.Sockeye salmon and burbot are the only spec1es that do not use tributaries extensively for important life history phases.Secondly,the resident species make little use of side channel, side slough or upland slough habitats,whereas the anadromous species (Balmon)frequently use these habitats.The most common use of the mainstem hnbitat type is for migration and movement although resident species also overwinter in the mainstem. 42187711 850227 2-13 - ..... Habitat requirements associated with migration and movement are less critical and restrictive than for the other life history categories. Suitable depth and velocity conditions exist over a broad range of mainstem flows,and flow requirements to support migration and movement would not be restrictive to project operation.Flow requirements to satisfy the more critical needs of rearing and spawning/incubation will also satisfy the habitat needs for migrat ion.Therefore,habitat requirements for rearing and spawning/incubation were emphasized for the remainder of the analysis. The four sensitive habitat types from Table 2.2-1 (MS,SC,TM and SS)were selected for comparison based on their use for rearing and spawning/ incubation (see Table 2.2-3). (~~)Mainstem habitat is used mostly for rearing,especially overwintering. Use of the mainstem by chum salmon is transient and short-term during their downstream movement to Cook Inlet.The major use of mainstem"habitat by arctic grayling,rainbow trout and Dolly Varden is for overwintering.The total area of mainstem habitat will be greater during the winter under the expected range of project flows than under natural flows.In addition,the populations of all the resident species 1.n the Middle River,including burbot,are characterized as low density • (:!!!)Arct ic grayl ing and rainbow trout use tributary mouth habitat for rearing during the ice-free seasons.Use by rainbow 1.S transient,occurring mostly in the late summer and fall.The total area of this habitat will be greater and more stable under the lower and more stable mainstem flows during project operation (Trihey 1984). (.§f)Side channel habitat 1.S used by chino~k salmon for rearing and chum salmon for spawn1.ng.The chum salmon spawning is limited to sites with sufficient upwell ing condit ions and accounts for onl~approximately five percent of the total chum spawning in the Middle River Basin. 42:187711 8~j0227 2-14 - Table 2.2-3 SUSITNA HYDROELECTRIC PROJECT PRIMARY UTILIZATION OF SENSITIVE HABITAT TYPES BY EVALUATION SPECIES Habitat Types .- ! EV~lluation SpE~cies Chinook Salmon Chum Salmon Coho Salmon Sockeye Salmon Pink Salmon Arctic Grayling Rainbow Trout Dollly Varden Burbot Mainstem R R R R S,R Side Channel R S Side Slough R S ,R S,R Tributary Mouth R R ..... S _.spawning/incubation R -.rearing 422501/TBL 850204 2-15 "'"" ..- Large numbers of chinook juveniles rear in side channels through most of the summer and early fall.The use of this habitat appears to be important to chinook production in the Middle River.Therefore,chinook rearing in side channels was selected as one of the critical uses of a sensitive habitat for primary consideration 1n developing environmental flow requirements. (5S)Side sloughs are used by salmon species for both rearing and spawning/incubation.The chinook salmon rearing in side sloughs during the ice-free season is a lesser component of the total population than those re,aring 1n side channels.Flow requirements to maintain side channel habitat would also serve chinook rearing in side sloughs.Environmental ..- flow cases designed to protect chinook rearing in side channels also provide for overwintering in side sloughs since,for the most part,the same fish use both habitats. Chum and sockeye salmon use side sloughs for both spawo1ng and rearing. Sockeye use of this habitat is so similar to chum,in time and location, that their habitat needs can be provided by concentrating on the more abundant chum salmon.Both species use side sloughs for short term,initial rearing prior to outmigration to Cook Inlet or movement to another habitat type.Chum salmon utilize side sloughs extensively for spawning.This is the most intensive use of a sensitive habitat in the Middle River for spawning.Therefore,chum salmon spawning in side sloughs was selected as another critical use of a sensitive habitat for development of environmental flow cases. 2.2.3 Compatibility with Mitigation Policy The alternative flow cases had to be compatible with the mitigation policies and procedures presented in the License Application (Exhib.E,Vol.6A,pp. E-3-3 to E-3-6 and E-3-147 to E-3-150).The flow cases had to function well with other mitigation measures to result in no-net-Ioss of fish production from the Susitna System.The flow cases also had to provide for habitat of sufficient quality and quantity to maintain natural reproducing populations to the greatest extent possible,consistent with other project objectives. ....42187711 850227 2-16 - ..... The environmental flow cases designed and selected for analysis emphasized the habitat needs of the evaluation species which were considered most important and most sensitive to anticipated changes from natural conditions. The flow c,ases were designed to mitigate potential impacts by using flow releases to maintain natural production in existing habitats. 2.3 CHARACTERISTICS OF THE ALTERNATIVE ENVIRONMENTAL FLOW CASES Eight 1984d)• alternative flow cases were selected for analysis (Harza-Ebasco The eight cases can be combined into three general groups,as ..... ..... follows: 1.cases designed to mitigate impacts on chum salmon spawning in side sloughs, 2.cases designed to mitigate impacts on chinook salmon rearing 1.n side channels, 3.cases designed to mitigate both I and 2,above. Ea:ch environmental flow case is made up of a set of weekly m1.n1.mum and ma,ximum flow constraints within which the project must operate.The project will generally operate by storing the high summer natural flows for release in,the winter when energy demand is greatest.Therefore,summer minimum and winter maximum flow constraints are the most important.Summer maximum and winter minimum flow constraints are still necessary to provide guidelines for operation under unusual circumstances. Figures 2.3-1,2.3-2,and 2.3-3 are generic illustrations of the three groups of flow cases listed above.The first figure focuses on chum salmon spawning in side sloughs (Figure 2.3.-1).The gradual increase of minimum constraints in May is to assure adequate downstream passage conditions for outmigrant chum juveniles and to establish a higher base flow in preparation for the June spiking flow.The large spiking flow in June is designed to 42:187711 850227 2-17 overtop the upstream berms of the major side sloughs and clear them of deposited sediments and debris.This flow spike would be necessary only every three or four years.The relatively low minimum constraint during' July is to provide sufficient mains tern passage conditions for upstream migrant adults.The increased minimum constraints from late July to mid- September are to establish a base flow sufficient to provide the chum adults with enhanced access conditions into the side sloughs.The spiking flows in August and September are provided to further improve access conditions. Maximum flow constraints during the winter are established to prevent overtopping of the upstream berms when and where an 1.ce cover is not present,and to establish criteria for construction of artificial berms if they are necessary and feasible. Flow cases to mitigate potential impacts on chinook salmon rearing in side channels differ markedly from the first group (Figure 2.3-2).The absence.... of spiking flows 1.S the most obvious di fference •Spiking flows are not needed 1.n these cases because local flow in the sloughs would provide adequate access conditions for the small,juvenile chinook.Minimum sunnner constraints are established to maintain a desired quantity of side channel rearing habitat and increase flow stability to the greatest extent possible. Malximum winter flow constraints are intended to protect overwintering sites iIll side sloughs used by the chinook juveniles. Flow cases to mitigate impacts on both chum spawn1.ng and chinook rearing are combinations ofsimply (E'igure 2.3-3).Flow the characteristics of the other two groups cases in this group were generally formed by combination of two flow cases,one each from groups one and two,using the malximum and minimum constraints in each week that were most restrictive on flows,were also added for some cases. project operation.Some refinements,such as the magnitude of spiking The combination of attributes from the cases illustrated in Figures 2.3-1 and 2.3-2 would have no significant adverse effects on mitigation for chum spawning.However,there may be some adverse results for chinook rearing due to the temporcary loss of habitat stability caused by spiking flows. 42187711 8~)0227 2-18 111 1 J 1"1 ~1 c~1 1 c--l eel 1 ~e~l J 11' MITIGATE WITH FLOW FOR CHUM SALMON SIDE SLOUGH SPAWNING HABITAT DECNOVOCTSEP NOTES: 1.DISCHARGE FOR SUSITNA RIVER AT GOLD CREEK 2.SHADED AREA REPRESENTS THE RANGE OF DISCHARGE FOR PROJECT OPERATION , AUGJULJUNMAYAPRMARFEBJAN ~"''''''''''''''''1 "f I ~I 1-·I I I ~""'"',,"r''''''')5:itiiiijnm,llli~lrili!!~l!l~~ -4 o 10,000 •50:000.I I .'.''.''.'.'.''':.,':':.:':.:.:.,.:,:.,.:.:.:.:.:.:.:.:-:.:.:.:.:.:.:.:.'.:.:.:.:'::".~.:-",:.,.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:':-:':.:':':'•.:.,,*i • 40,000 I I I """""'"UJ ILo-....- W 30,000 I I I I:!:!:!:\if::::t/(::::;:~:~:;:I:;:;:);!;!;f;j;!;i;!;!;!;!;!;!;!~!;!;!\ CJa:« %o UJ 20,000 I I I-C N I I-' \0 HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY I •••1 I 1 ]1 ]11 ·1 I 1 1 1 ] MITIGATE WITH FLOW FOR CHINOOK SALMON SIDE CHANNEL REARING HABITAT 50,000 Iii iii i ,•• -40,000 I I.I I I I I I I SEP NOTES: 1•.DISCHARGE FOR SUSITNA RIVER AT GOLD CREEK 2.SHADED AREA REPRESENTS THE RANGE OF DISCHARGE FOR PROJECT OPERATION AUGJULJUNMAYAPRMARFEBJAN 10,000 W 30 000 I I I I I ICJ' a: c( :::E:o t/)is 20,000 I I I I I ---. t/) u.o-....... N I No HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTtlORITY 1 J --1,._J).1]c__J I -II c-l ~--11 MITIGATE WITH FLOW FOR BOTH CHINOOK SALMON SIDE CHANNEL REARING HABITAT AND CHUM SALMON SIDE SLOUGH SPAWNING HABITAT "C5c:nm MAX 40,000 •I I I I I I !I I 50,000 I I i I I I I I I I r I I I I I I I I I I NOTES: 1.DISCHARGE FOA SUSITNA RIVER A T GOLD CREEK 2.SHADED AREA REPRESENTS THE RANGE OF DISCHARGE FOR PROJECT OPERATION oj I ( I r I I I I I J f :::::::::::t z 10,000 ,..." (/)u. ~.30,000 I I I I I W C'a: c( :r:o 20,000 I I I I I UJ-Q 'f N..... JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY 3.0 SELECTION OF FLOW CASE E-VI 3.1 FLOW CONSTRAINTS Maximum and minimum flow constraints for Gase E-VI were developed on a weekly basis for each week of the year.This information is presented in Table 3.1-1 and Figure 3.3-1.The flow constraints can be separated into three major divisions:winter flows,sunnner flows,and transitional flows. The most important winter flow constraints are maximum flows s~nce normal project operation would produce discharges greater than the naturally occurring flows during the November to April period.The selected winter maximum (October-Apri 1)is intended to establish a boundary near the upper range of operational flows that would result in flow stability and provide a reasonable level of protection to over-wintering habitat.Side sloughs are especially important in this context because chinook juveniles utilize this habitat for over-wintering.The 16,000 cfs maximum flow would prevent overtopping of all the major sloughs prior to freeze-up,and stabilize habitat availability during ice-cover periods. The winter minimum flow 1S established to prevent habitats.The 2,000 cfs minimm is chosen based represents a high mean natural winter flow. dew~tering of rearing on natural flows and ..- Flow constraints during the winter to summer transition period (mid to late May)are intended to maintain flow stability and prevent rapid drops in discharge due to decreasing power demand in May and to gradually increase flow to summer levels.The minimum flow constraints are most important during this period • Summer flow constraints (water weeks 36-48)are designed to maintain rearing habitats and provide greater flow stability.Chinook juveniles are acquiring the major portion of their freshwater growth during this period 421863 850227 3-1 C---l 1 I 1 1 1 j )·1 J I --) Table 3.1-1 co,j::- SUSITNA HYDROELECTRIC PROJECT UlN FLOW CONSTRAINTS FOR ENVIRONMENTAL0...... NCO FLOW REQUIREMENT CASE E-VI NO'\ -.l W Water Gold Creek Flow (cfs)Water Gold Creek Flow (cfs) Week Period Minimum Maximum Week Period Minimum Maximum-- 14 31 Dec.-06 Jan.2,000 16,000 40 01 July -07 July 9,000*35,000 15 07 J?n.-13 Jan.2,000 16,000 41 08 July -14 July 9,000*35,000 16 14 Jan.-20 Jan.2,000 16,000 42 15 July -21 July 9,000*35,000 17 21 Jan.-27 Jan.2,000 16,000 43 22 July -28 July 9,000*35,000 18 28 Jan.-03 Feb.2,000 16,000 44 29 July -04 Aug.9,000*35,000 19 04 Feb.-10 Feb.2,000 16,000 45 05 Aug.-11 Aug.9,000*35,000 20 11 Feb.-17 Feb.2,000 16,000 46 12 Aug.-18 Aug.9,000*35,000 21 18 Feb.-24 Feb.2,000 16,000 47 19 Aug.-25 Aug.9,000*35,000 22 25 Feb.-03 Mar.2,000 16,000 48 26 Aug.-01 Sep.9,000*35,000 23 04 Mar.-10 Mar.2,000 16,000 49 02 Sep.-08 Sep.8,000 35,000 24 11 Mar.-17 Mar.2,000 16,000 50 09 Sep.-15 Sep.7,000 35,000 W I 25 18 Mar.-24 Mar.2,000 16,000 51 16 Sep.-22 Sep.6,000 35,000 N 26 25 Mar.-31 Mar.2,000 16,000 52 23 Sep.-30.Sep.6,000 35,000 27 01 Apr.-07 Apr.2,000 16,000 1 01 Oct.-07 Oct.6,000 18,000 28 08 Apr.-14 Apr.2,000 16,000 2 08 Oct.-14 Oct.6,000 17,000 29 15 Apr.-21 Apr.2,000 16,000 3 15 Oct.-21 Oct.5,000 16,000 30 22 Apr.-28 Apr.2,000 16,000 4 22 Oct.-28 Oct.4,000 16,000 31 29 Apr.-05 May 2,000 16,000 5 29 Oct.-04 Nov.3,000 16,000 32 06 May -12 May 4,000 16,000 6 05 Nov.-11 Nov.3,000 16,000 33 13 May -19 May 6,000 16,000 7 12 Nov.-18 Nov.3,000 16,000 34 20 May -26 May 6,000 16,000 8 19 Nov.-25 Nov.3,000 16,000 35 27 May -02 June 6,000 16,000 9 26 Nov.-02 Dec.3,000 16,000 36 03 June -09 June 9,000*35,000 10 03 Dec.-09 Dec.2,000 16,000 37 10 June -16 June 9,000*35,000 11 10 Dec.-16 Dec.2,000 16,000 38 17 June -23 June 9,000*35,000 12 17 Dec.-23 Dec.2,000 16,000 39 24 June -30 June 9,000*35,000 13 24 Dec.-30 Dec.2,000 16,000 *Minimum summer flows are 9,000 cfs except in dry years when the minimum will be 8,000 cfs. A dry year is defined by the one-in-ten year low flow. .- and they utilize side-channel sites that are directly affected by mainstem discharge (ADF&G 1984b).A 9,000 cfs mimimum flow would maintain 75%of the existing habitat quantity at sites presently utilized by chinook and increased flow stability would improve babitat quality over natural conditions. Flow constraints during the summer to winter transition period (September and October)are intended to mai~tain flow stability and prevent rapid drops in flow prior to high winter power demands.Minimum flow constraints are not important in this period. 3.1.1 Flow Stability Constraints Flow stability criteria are required to protect the instream flow uses of the river in addition to weekly average minimum and maximum flow constraints.These constraints would be indexed to Watana discharge when Watana is operating alone,and to Devil Canyon discharge when Devil Canyon is operating with Watana,rather than to discharges measured at the Gold Creek gaging station. Indexing to powerhouse flows rather than Gold Creek flows 1.S desirable because of: - 1. 2. The variability in flow from the intervening area between the powerhouses and Gold Creek,and The time required for changes 1.n powerhouse discharge to be reflected in Gold Creek discharges. 3.1.1.1 Watana Only Operation Watana operation will follow two guides,one is a long-term operation guide on a weekly basis and the other is a short-term operation guide on an hourly basis. 421863 850227 3-3 r - .... Long-term operation will use a family of rule curves as a guide for seasonal adjustment of flow for power generation and downstream flow requirements. The expected discharges in 52 weeks of the year from the Watana powerhouse are determined from trial computations.These are the discharges which can most likely produce the required energies by keeping thermal energy generation constant at one value throughout the winter (October to mid-May) and May)and constant at a different value throughout the summer (mid May to September).The expected discharge versus time is a smooth curve with high discharges in winter,low discharges 1n summer,and gradual changes at transitions.The weekly discharge during operation could be 63,80,100, 120,or 140 percent of the expected discharge.The variation of discharge between two consecutive weeks is limitd to 20 percent.However,the limitation can be violated if the discharge has to be increased to maintain the minimum flow requirement at Gold Creek.Thus,the weekly average flow at Gold Creek does not drop below the minimum weekly flow requirement even when the intervening flow between Watana and Gold Creek is very low. With a given weekly average flow obtained from the long-term operation guide the short-term operation wi 11 be fit to the system load demand within a week under the environmental constraints.The largest allowable discharge at Watana during any given week will be 110 percent of the weekly average discharge.The smallest allowable discharge will be 90 percent of the average for the week.If intervening flows between Watana and Gold Creek decrease during the week and the Gold Creek discharge is below the minimum weekly flow constraint Watana discharge will be increased above 110 percent of the weekly Watana average in order to maintain the minimum weekly average flow requirements at Gold Creek.If the average flow for a given week approximates or equals the m1n1mum weekly flow requirements,there may be times during the week when the Gold Creek discharge is less than the minimum weekly flow requirements.This deviation will not exceed 800 cfs. On an hourly basis,the maximum allowable rate of change of discharge at Watana will be 10 percent per hour of the weekly average Watana discharge under increasing discharge conditions and 500 cfs per hour when discharge is 421863 850227 3-4 being reduced.When energy production and weekly average flows are being adjusted from one week to the next,the same rates of change of discharge will apply and will be based on the weekly average discharge for the upcoming week.The discharge change will occur during the early morning hours of a Sunday or a Monday.The change will be separate from,and additional to,the 10 percent deviation from the average permitted during the remainder of the week. 3.1.1.2 Watana and Devil Canyon Operation r-, - - - In long-term operation,Watana will be used for seasonal regulation of flow whereas Devil Canyon will be kept as full as possible.Devil Canyon will not release water unless the release from Watana for power is not enough to satisfy the minimum flow requirement at Gold Creek.Once the Watana release for power is greater than needed to satisfy downstream requirements,Devil Canyon will be refilled immediately. On an hourly basis,in -short-term operation"discharges from Watana can be varied without restriction because Watana wi.ll discharge directly into the Devil Canyon reservoir.Devil Canyon will be operated to regulate and stabilize downstream flows. The largest allowable discharge at Devil Canyon during any given week will be 110 percent of the weekly average Devil Canyon discharge and the smallest allowable discharge will be 90.percent of the average for the week.Since the Devil Canyon powerhouse will be base loaded,flow changes will generally be in response to changes in daily average or weekly average energy demand, not hourly demand.During the early years of Devi 1 Canyon operation the entire Railbelt system energy demand in the sunnner can be met by Devil Canyon without operating Watana.It is preferable to use the Devil Canyon powerhouse during these periods to avoid cone valve discharges at Devil Canyon and resulting cooler water temperatures (See Section 3.4.2.1). Therefore,flow changes under these conditions will be in response to hourly demand changes. -421863 850227 3-5 .... .... If intervening flows between Devil Canyon and Gold Creek decrease during the week and the Gold Creek discharge is below the minimum weekly flow constraint,Devil Canyon discharge will be increased above the 110 percent weekly average flow limit in order to maintain the minimum weekly average flow requirements at Gold Creek.During a week when the Gold Creek weekly average flow is being maintained at the minimum flow requirement,there may be times during the week when the Gold Creek discharge is less than the minimum weekly flow requirement.This deviation will not exceed 900 cfs. The maximum rate of change of the powerhouse discharge at Devil Canyon wi 11 be 350 cfs per hour whether discharge is being increased or decreased.At a discharge of 9000 cfs at Gold Creek,a 350 cfs change corresponds to a 0.1 foot difference in stage at Gold Creek. 3.1.2 Dam Safety Criteria If the Watana reserV01r level exceeds elevation 2185.0 feet,dam safety criteria will supersede both weekly flow constraints and flow stability constraints.Environmental considerations are built into the dam safety criteria as discussed herein.Project operation at Watana will be similar for both Watana operating alone and Watana operating with Devil Canyon once the Watana reservoir reaches elevation 2185.0 or higher. 3.1.2.1 Watana Only Operation If the water level 1n Watana reservoir reaches elevation 2185.0 and continues to r1se,Watana discharge will be increased by releasing water through the outlet works.Because the intake to the outlet works 1S approximately 150 feet below the water surface,operation of the cone valves results in reduced downstream water temperatures.In order to provide for as gradual a change in water temperature as possible,the following guidelines will apply: ....421863 850227 3-6 1.Supply as much energy as possible from the Watana powerhouse within the constraints of the system energy demand,other generation and Watana powerhouse capacity. ..... 2.Increase the outlet works discharge at the estimated minimum rate required to prevent the water level from exceeding elevation 2185.5.If the inflow to the reservoir is more than 24,000 cfs greater than the powerhouse can discharge,then the release from the cone valves will be 24,000 cfs when the water level reaches elevation 2185.5. .... - - If the outlet works are not releasing water at full capacity and the water level r1ses above elevation 2185.5,the outlet works will be opened immediately to full capacity.If the full capacity of the outlet works and powerhouse flow are not sufficient to discharge all the inflow the water level will continue to rise • If the water level exceeds elevation 2185.5 but does not reach elevat ion 2193.0 then the Watana discharge will remain relatively constant until the water level decreases to elevation 2185.5.If the water level starts to decrease below elevation 2185.5 then the outlet works will be closed in a gradual manner as they were opened.The rate of closure wi 11 be that estimated to cause the water level to reach elevation 2185.0 when the outlet works discharge reaches zero.The outlet works wi 11 be completely closed before the water level is allowed to decrease below elevation 2185.0. It is estimated that there is less than a 1 1n 50 chance that in anyone year the water level will continue to rise to elevation 2193.0.If the water level reaches elevation 2193.0 and continues to increase,the spillway will be opened.Since it is expected that spillway operation will result in a greater potential for deleterious gas concentrations in the river downstream,the spillway wi 11 also be opened up as gradually as possible, consistent with providing sufficient freeboard on the dam to meet safety 421863 850227 3-7 -- .... - - requirements.The powerhouse and outlet works releases will continue as before,and the spillway will be opened at the estimated minimum rate required to prevent the water level from exceeding elevation 2193.3.If the water level reaches elevation 2193.3 and continues to rise,the spillway gates will be opened as much as needed to prevent the water level from increasing any further.It is estimated that there is less than a 1 in 10,000 chance in any year that the water level would exceed elevation 2193.3 or the spillway would be discharging more than 120,000 cfs. If the reservoir water level reaches elevation 2193.3 and the spi llway, outlet works and powerhouse are insufficient to pass the inflow,the water level will increase.Watana discharge will not be controlled aga1n until the water level decreases to elevation 2193.3.When this occurs,the spillway will be closed gradually in a manner estimated for the water level to reach elevation 2193.0 when the spillway is discharge 1S zero.The spillway gates will be completely closed before the water level is allowed to decrease below elevation 2193.0. 3.1.2.2 Watana and Devil Canyon Operation Project operation at Watana with both Watana and Devil Canyon operating will be similar to Watana only operations when the water level 1n Watana reservoir exceeds elevation 2185.0,in the early years of Devil Canyon operation.However,while Watana reservoir is filling in the spring,and before the water level reaches elevation 2185.0,the Devil Canyon.powerhouse will be used to generate system energy demands.Releases would be made from the Watana outlet works to keep Devil Canyon reservoir levels high.This policy was adopted for the purpose of minimizing downstream temperature effects (See Sec.3.4.2.1).When the Watana water level reaches elevation 2185.0 it 15 necessary to switch energy generation from Deyil Canyon to Watana in order to meet the criteria of pas-sing the 50 year flood without using the spillway.The change from the Devil Canyon to the Watana powerhouse can be made in a gradual manner,but in no case would the Watana water level be allowed to rise above elevation 2185.5 without the Watana 421863 850227 3-8 .... - powerhouse supplying all avai lable system energy demands and the Watana outlet works releasing at full capacity.After the system load 1S transferred from Devil Canyon to Watana the operation at Watana would be identical to that for Watana only operation. When the Watana water level reaches elevation 2185,operation at Devi 1 Canyon will be relatively simple.Devil Canyon reservoir will be allowed to fill while minimum flow requirements are being met.While the Devil Canyon reservoir is filling,the outlet works will be opened up in a gradual manner estimated to prevent the water level from exceeding elevation 1455.0.When the water level reaches elevation 1455.0 the outlet works will be opened as much as necessary to keep the water level stable.In this period,Devil Canyon wi 11 operate as essentially a run-of-river project,passing Watana outflows and intervening flows.The rates of change of Devil Canyon discharge will be similar to those for Watana with small modifications resulting from variations in intervening flow. It is estimated that Devil Canyon can pass all of the Watana outflows and all intervening flows through its outlet works while the Watana water level is at or below elevation 2193.0.If the Devil Canyon water level begins to increase above elevation 1455.0 and the outlet works are functioning at their full capacity of 38,500 ds,the Devil Canyon spi llway must be opened to maintain freeboard on the dam.The spi llway wi 11 be opened at whatever rate is necessary to keep the pool level at elevation 1455.0.It is estimated that the chance tqe spillway would be operated in anyone year is less than 1 in 50.There 1S less than a 1 in 10,000 chance that the spillway would be operated at a flow exceeding 123,000 cfs or that the Devil Canyon water level would exceed elevation 1455.o.If the spi llway were opened completely and the reservoir level continued to rise,discharge from Devil Canyon would be uncontrolled.Control would not be regained until the water level receded to elevation 1455.0.When the water level decreases to elevation 1455.0 the spillway and outlet works will be closed in a manner to keep the water level at elevation 1455.0. 421863 850227 3-9 .... ! When system energy demands increase.the releases made-from Watana to keep Devil Canyon reservoir levels high can be made from the Watana powerhouse rather than the out let works.Because of the increased energy demands. filling of Watana reservoir will occur less frequently and later in the year.There will be a much decreased chance that the outlet works at either Watana or Devil Canyon will have to be operated or that the spillways would be opened.The operation to pass floods when the Watana reservoir reaches elevation 2185.0 would differ slightly from the early years of Devil Canyon operation.If the water level at Watana were to rise above elevation 2185.0 it would not be necessary to switch all the energy generation to Watana. Only that load would be switched which would be necessary to keep the Watana water level from exceeding elevation 2193.0 for the 50 year flood.It is estimated that this requires a Watana powerhouse discharge of 7,000 cfs. Additionally,the increased energy demand means that Devil Canyon would have the capacity to discharge some flow from its powerhouse before it becomes necessary to open up the outlet works there. Overall,operation of the two dams with greater system energy demands will result in more gradual changes in discharge and less chance of outlet works or spillway operation than in the first years of Devil Canyon operation. 3.1.3 Emergency Situations Under normal circumstances,the minimum flow requirements at Gold Creek will be maintained at all times unless otherwise agreed to by the appropriate State and Federal agencies.In emergency situations.if powerhouse operation is not possible,outlet facilities wi 11 be operated to meet the flow requirements.Correspondingly,if another part of the energy generation system 1.S temporarily lost.Watana and Devil Canyon will be operated to make up the deficit.The resulting discharge variation may exceed the maximum variation rate of 10 percent.and discharge may reach the maximum flow constraint.However.the discharge at Gold Creek will not be allowed to exceed the maximum weekly flow requirement and the rate of change of discharge will be constrained by the rates established in Section 3.1.1. 421863 850227 3-10 ~ I - 3.2 POWER AND ENERGY CONSIDERATIONS 3.2.1 Reservoir Operations Program In refining the flow requirements from the Case C to the Case E-VI flow reg1.me t the energy enalysis was conducted using the reservoir operations program described in the License Application (Exhibit E t Chapter 2,Section 3.2 pp.E-2-55 to E-2-57).A number of modifications were made to the input data and the reservoir operations program itself to incorporate additional and revised data,to elim1nate possible inconsistencies in the analysis and to improve the estimate of project benefits.The revisions,modifications, and additional data are described below. First,since submitting the License Application,two additional years of discharge data have become available.These have been incorporated in the data base,increasing the number of years of energy simulation for each electrical demand level from 32 to 34 years. Second,the flow data have also been revised.Because of the rare occurrence of the low flows during water year 1969,water year 1969 was modified 1.n the License Application (p.E-2-57).Water year 1969 flows were adjusted to provide an annual flow which had a probability of occurrence in anyone year of one in thirty.Reservoir operations planning was then based on this low flow event.The current Case E-VI refinement studies do not include these modifications but utilize the unmodified natural hydrology to determine the annual energy benefits and environmental impacts (See Appendix D). Third,reservoir generation studies were based on a weekly time step. Reservoir generation studies used to determine the project economics presented in the License Application were based on a monthly time step. Since this was considered to be too large a.time step to adequately a'ssess the aquatic impacts,a weekly reserV01.r operations analysis was conducted to provide a weekly time series of flows.The derivation of monthly and weekly 421863 850227 3-11 - .... average in flows to Watana and Devil Canyon reservo~rs is described in Appendix D. For Case E-VI,the weekly reservoir operations program was used for both economic and environmental studies to ensure consistency.Monthly energy data were generated by summing weekly energy data for appropriate weeks and fractions of weeks corresponding to the various months.This monthly energy information was then utilized in the General Electric Optimized Generation Planning (OGP)program to determine project economics. Fourth,the reservoir operations program was modified by developing a family of rule curves.These improved the estimated project economic 1:>enefits by minimizing weekly changes in energy production and at the same time stabilizing flow from week to week.Large changes in weekly inflow to the Watana reservoir did not result in a high energy output during a week when flows were high,and then decrease the following week when flows were lower. Fifth,another change from the License Application ~s the operational strategy for dispatching project energy on a monthly or weekly basis.In the License Application,it was assumed that the Susitna project would be operated to generate monthly energies tha.t maintained an approximately constant proportionality to the monthly system electrical demand.If the annual energy from the project represented one half of the annual system demand,approximately one half of the monthly system electrical demand would be provided each month by the Susitna project.Because the monthly electrical demand is greater ~n winter than summer,maintaining project energy generation at a rate proportional to demand would result ~n correspondingly greater energy generation from the project in winter than summer.If the resulting flows were less than the flow requirements,energy generation was increased until the flow requirements were met.This had the effect of reducing the energy available for generation in other months • 421863 850227 3-12 ,..., - - ...... Current operational strategy has been adjusted to capture additional economic benefits through what is termed "constant thermal generation."The reservoirs are almost full at the end.of September whi Ie they are at the lowest levels in mid-May.Energy distribution within summer,mid-May to September,and that within winter,October to mid-May,can be varied as a function of water surface variation without reducing total energy production.Therefore,the turbine discharges are so adjusted that the energy distribution will keep thermal energy generation constant as much as possible.By providing the same amount of thermal energy each week within the winter and summer periods,advantage can be taken of the most fuel efficient thermal units in the system.Cost savings occur because it is more economical to provide the annual thermal energy by running the least- cost thermal units throughout the season rather than running them for part of a season along with other less efficient units. In constant thermal generation,the seasonal energy available from the project is subtracted from the system seasonal electrical energy demand to yield the amount of energy to be produced by thermal generation.The weekly thermal energy is distributed evenly throughout each week of the season.The thermal energy is subtracted from the weekly system electrical energy demand to yield the energy to be provided by the project.Since winter system electrical energy demand is higher than summer demand,this operational strategy results in more energy being produced by the project in winter.If flows of the Susitna River at Gold Creek are ever less than the flow requirements,energy production is increased until the flow requirements are satisfied.Energy generation from the Susitna proj ect is correspondingly reduced in the remainder of the year.Energy generation between October and May may also be constrained by the available reservoir storage volume and local winter reservoir inflow • A key parameter in the reserV01r operation studies is the electrical energy demand forecast.In the original License Application,economic and environmental studies were based on a preliminary medium-load forecast prepared by Battelle Northwest.In the revised License Application, -421863 850227 3-13 - ...... I, submitted in July 1983,the energy forecast and economic studies were updated on the basis of oil price forecasts by Sherman H.Clark Associates. The resulting electrical forecast has been termed the S.H.Clark NSD forecast and is the APA Reference Case forecast.At the time of the revised license submittal,Exhibit E of the original application was not revised. However,subsequent information provided to the FERC was based on the S.H. Clark NSD forecast.This report uses the S.H.Clark NSD forecast. 3.2.2 Watana Operation -1996 and 2001 Watana operation studies were conducted using the APAReference Case electrical energy demand forecasts for 1996 and 2001,and the flow constraints discussed in Section 3.1.Reservoir operation in the year 1996 is representative of the early years of Watana only operation and 2001 1.S the last year of Watana only operation.The energy produced in each year 1.8 similar.Mean annual energy production is 3400 GWH in 1996 and 3440 GWH 1.n 2001. In the 34 years of energy simulations,annual energy production var1.es from a low of 2320 GWH for both the 1996 and 200.1 demands,to highs of 3930 GWH for the 1996 demand and 3980 GWH for the 2001 demand.Firm annual energy was assumed to be based on the third lowest energy generation (94% probability of exceedance)because of the high return period of the minimum flow year (water year 1969).This resulted in a firm annual energy of 2860 GWH. With the 1996 demand of 4670 GWH,energy generation from the Watana project and other existing hydro-projects is sufficient to meet the entire system load·during the week containing the annual peak demand,without the assistance of thermal generation,26 percent of the time.However,by 2001, the Railbelt electrical load will have increased sufficiently that the system hydro-generation must be supplemented with thermal energy during the week containing the annual peak demand,based on the 34 years of simulation. 421863 850227 3-14 .... 3.2.3 Watana and Devil Canyon Operation -2002 and 2020 Watana and Devil Canyon operation studies were conducted using the APA Reference Case electrical energy demand forecasts for 2002 and 2020,and the flow constraints discussed in Section 3.1 In 2002,after allowing for existing hydro-generation,the Watana and Devil Canyon projects can meet the entire Railbelt electrical load based on the 34 years of simulation.Even in an extreme dry year such as water year 1969,the annual electrical energy needs of the Railbelt can be met by hydroelectric generation. By the year 2020,system energy requirements wi 11 have increased to 8312 GWH.Even in the wettest years of the study period,the available hydroelectric energy will be insufficient to meet the annual energy needs of the Railbelt area.Average annual energy production from the Susitna projects will be 6850 GWH.Watana and Devil Canyon will each contribute approximately half the project energy.During the extreme dry sequence, such as occurred in water years 1969 and 1970,Watana and Devi 1 Canyon together could produce 5090 GWH of annual energy.Firm annual energy was determined to be 5770 GWH based on the year with the third lowest annual energy production in the 34 years of simulation. There is a 35 percent probability that system hydro-generation in 2020 will be capable of meeting the entire system energy demand during the week containing the annual peak demand.During other times of the year some thermal energy would be required.The maximum annual energy production from both Watana and Devil Canyon would be 7720 GWH • 421863 850227 3-15 - - - 3.3 PROJECT FLOWS AND RESERVOIR ELEVATIONS 3.3.1 Watana Operation -1996 and 2001 3.3.1.1 1996 Electrical Energy Damand Forecast Weekly discharge and reservoir elevations based on the reservo~r operations studies for a 1996 electrical energy demand forecast of 4670 GWH,are presented in Appendix E hereto (Table E-5). The maximum weekly average Watana turbine discharge during the 34 year simulation ~s 12,600 cfs.After accounting for other existing system hydroelectric energy,the energy associated with this discharge is sufficient to meet the maximum system energy demand during the week containing the peak annual demand.The minimum weekly average Watana turbine discharge is 3700 cfs. The mean average turbine discharge during the period of peak winter demand is approximately 10,000 to 11,000 cfs.The mean weekly average turbine discharge in summer is in the range of 6,000 to 7,000 cfs. Turbine discharges at Watana will normally vary gradually from one week to the next.In the 34 years of simulation,the maximum change in weekly turbine discharge was 2,700 cfs.Cone valve releases at Watana are required in 25 of the 34 years of simulated project.operation as presented in Table 3.3-1 and 3.4-1.In 18 of these years the release is required because the reservoir ~s full.There is approximately a 53 percent chance,annually, that Watana reservoir will fill to elevation 2185 feet,thereby necessitating a cone valve release.Only in the simulation of water year 1967 did the cone valves operate at their full capacity of 24,000 cfs.The volume of water released through the cone valves is approximately 3 percent of the total inflow to Watana reservoir. Cone valve releases occurred between mid June and early October with the highest releases occurring between mid July and late September. 421863 850227 3-16 "!II )1 1 -J -.1 I 1 I )-1 1 1 1 Table 3.3-1 WATANA CONE VALVE OPERATION 1996 ENERGY DEMANDS WEEK BEGINNING W I t-'.... JUNE JULY AUGUST SEPTEMBER OCTOBER YEAR 17 ;u..1 8 15 22 29 5 12 19 26 2 9 16 23 1 1951 248 4252 1955 375 593 477 53 12187 10611 6219 3490 1006 1956 12923 9312 6712 4151 8568 7988 2253 1957 1546 7361 6643 1958 204 1959 1611 13636 3359 502 222 1960 689 1558 1961 38 1962 15 415 507 15409 12846 12733 12619 12750 11649 4504 2064 2002 1963 51 283 10955 10600 5825 4269 1751 570 1964 466 52 5832 4528 1613 1965 1785 8195 10546 2724 1967 24000 18805 9469 16188 6402 2452 1968 1731 1655 1969 67 192 1971 5665 11857 4764 1618 273 1972 83 345 227 321 182 1065 4303 8380 4047 1973 172 734 644 141 186 1975 3196 2070 8372 7200 4745 1976 531 683 980 1135 1087 1977 28 1012 1356 4766 4097 2116 1979 3 1980 3638 2481 316 1981 3537 23911 13551 7855 4751 2561 544 1983 225 93 4218711 850219 ..... - - - The with-project flows at Gold Creek,based on the 34 years of simulation, are provided in Table E-5.Table E-l6 and Exhibit E-2 show the percent of time that discharges at Gold Creek would be equalled or exceeded for each week of the year.Figure 3.3-1 illustrates the discharges for each of the 52 weeks that would be exceeded 6,50 and 97 percent of the time.Mi~limum weekly flow requirements are met or exceeded 100 percent of the time. Normally,discharge during low flow periods (97 percent exceedance)is well above the .minimum flow requirements in winter,but at the minimum flow requirements in summer. During periods of high intervening flow between Watana and Gold Creek or during periods When Watana reservoir is at or above elevation 2,185,flows at Gold Creek may approach or exceed the maximum weekly flow requirements between May and September.There is no way to avoid this except by shutting off the turbines at Watana during periods of very high local inflow or releasing water prior to Watana reservoir reaching elevat ion 2,185.The latter could lead to a less than full reservoir at the end of the high flow period and thus a reduction in available energy • During normal operation in the winter,Gold Creek discharge remains well below the 16,000 cfs maximum flow requirement,even during the highest flow years. Because of the potential variations in local inflow between Watana and Gold Creek and because of a potential 20 percent variation in Watana turbine discharge,some flow variability in discharge at Gold Creek during a given week should be expected.The maximum variability would likely occur in the summer because of the higher and more variable intervening flows during that period. Weekly average discharges at Sunshine and Susitna Station are presented in Appendix E Tables E-6 and E-7,respectively.Flow duration data at these stations is presented in Tables E-17 and E-l8 and Figures E-4 and E-5.The change in discharge at these gaging stations from the Case C flow regime is not significant. 421863 850227 3-18 .... .... r Watana reservoir elevations at the end of each week are presented in Table E-5.Probabi lity di stribut ions of Watana reservoir surface el evat ions for the first week of October,January,April and July are presented in Figures 3.3-2 through 3.3-5 respectively.Figure 3.3-2 indicates the generally filled condition of the reservoir at the beginning of October (Le.62 percent of the time the reservoir is filled above elevation 2,180 feet).In lower flow years,the reservoir does not c.ompletely fill.Thirty-five percent of the time the reservoir elevation is between 2,155 and 2,180.In the extreme low flow year the reservoir is at elevation 2,134 feet by October 1,thus demonstrating the'severity of 1969 when compared to other years.By January 1,(Figure 3.3-3)the reservoirs draw down to between 2,130 to 2,155 except for the extreme low flow year.By early April (Figure 3.3-4).Watana water levels are between 2,095 and 2,110 feet 91 percent of the time.By July (Figure 3.3-5),there is wide range of possible reservoir water surface elevations because of the large variation in runoff in May and June. 3.3.1.2 2001 Electrical Energy Demand Forecast Weekly discharge and reservoir elevations based on the reservoir operation studies for a 2002 electrical energy demand forecast of 5117 GWH are presented in Appendix E hereto (Table E-8). As system electrical energy demand grows from 1996 to 2001,minor changes in weekly turbine dischrges at Watana will take place in years with high annual discharge.The maximum weekly average powerhouse discharge,based upon the 34 years of simulation,will increase from 12,600 cfs in 1996 to 13,200 cfs in 2001.The minimum weekly average turbine discharge would be 3,700 cfs if the annual flow were similar to the low flow year which occurred in water year 1969.During average and low flow conditions,project operation a?d hence turbine discharge would not he affected by demand during the period 1996 to 2001. 421863 850227 3-19 .- i""'" I - ..... ..... ..... Watana reservoir water levels for maximum,mean,and minimum conditions are shown in Figure 3.3-6.Reservoir inflow,outflow and water levels for the 34 years of simulation are depicted in Figures 3.3-7 to 3.3-9.Cone valve releases are required in 15 of the 34 years simulated.In 13 of these years the release is because the reservoir is full.There is a 38 percent chance that the reservoir will fill to elevation 2,185 feet.No situation arose where the cone valves were operated at maximum capacity.Table 3.4-2 summarizes the cone valve releases which were simulated to occur in 2001. Increased power demands in 2001 result in changes in turbine discharges and cone valve releases which are manifest in discharges at Gold Creek and \ locations further downstream.The with-project flows at Gold Creek for the 2001 demand are provided in Table E-8.Table E-20 and Figure E-7 show the percent of time that discharges at Gold Creek would be equalled or exceeded for each week of the year and Figure 3.3-10 illustrates the discharges for each of the 52 weeks that would be exceeded 6,50 and 97 percent of the time. Weekly average discharges at Sunshine and Susitna Station are also presented in Tables E-9 and E-10,respectively.Flow duration data for these stations are presented in Tables E-21 and E-22 and Figures E-8 and E-9. End of week Watana reservoir elevations are presented in Table E-8. Probability distributions of Watana reservoir surface elevations for the first weeks of October,January,April and July are presented ~n Figures 3.3-11 through Figure 3.3-14,respectively.The figures are similar to Ithosepresented for the 1996 level of demand • 421863 850227 3-20 .... .- 3.3.2 Watana and Devil Canyon Operation 3.3.2.1 2002 Electrical Energy Demand Forecast Weekly discharge and reserV01r levels based on reserV01r operations studies for a 2002 electrical energy demand forecast of 5238 Gwh are presented in Appendix F hereto (Tables F-6 and F-7). When Devil Canyon comes on line in 2002,there 1S more energy available from Watana and Devi 1 Canyon than can be used in the system,as discussed in Section 3.2.3.In each of the 34 years simulated,streamflows were adequate to provide system energy demands.For each powerhouse and for any week between early November and early May,turbine di scharge is simi lar for all 34 years simulated.For the period between early May and late October,year to year differences in turbine discharge result from variations in intervening flows,a policy designed to minimize temperature impact s (See Sec.3.4.2.1)and operation of the outlet works and powerhouse during floods. Appendix F,Table 6 provides Watana turbine discharge information for the 34 years of simulation.Table F-17 presents the Watana turbine discharge data in the form of a flow duration table.From early November to late Aprii there is a difference of only a few hundred cubic feet per second (cfs) b~tween the maximum and minimum flows for each week.From early May to late October,differences are greater.There is greater than a 94 percent chance that operation of the cone valves at Watana will be required because Watana reserV01r has filled to elevation 2,185.Based on the historic record there is a 59 percent chance that the cone valves will be operated at full capacity sometime during the year.Tables 3.3-2 and 3.4-3 illustrate the high frequency of cone valve discharges at the Watana reservoir.Cone valve releases occurred as early as mid June in the simulation and last until early October. Turbine discharge at Devil Canyon follows a pattern similar to that at Watana as indicated in Table F-7 and Table F-18.From early November to 421863 850227 3-21 I -].---1 --1 1 1 )-1 )1 I )1 ----1 1 --1 I Table 3.3-2 DEVIL CANYON CONE VALVE OPERATION 2002 ENERGY DEMANDS WEEK BEGINNING Vol ,I N N JUNE JULY AUGUST SEPTEMBER ",OCTOBER YEAR 17 24 1 8 15 22 29 5 12 19 26 2 9 16 23 1 1950 2807 10898 7209 2818 1951 5941 7926 7406 13905 18816 7281 7626 4671 1952 4876 17202 33443 13404 8418 4015 6040 8053 1992 102 1993 1953 5693 8430 9980 10709 14846 11414 7187 7518 10431 7013 5270 2473 1954 7971 20574 14451 14298 14146 12583 4264 2038 986 1955 10759 12342 16454 12951 11272 11650 16051 34184 10567 3965 1085 1956 18222 24067 24721 23207 20657 17328 14630 9637 6560 4315 9823 9081 1895 1957 11367 13850 15756 10625 10612 10352 8573 10194 7200 8540 7190 6890 1958 2356 11448 11041 35626 20393 10736 6799 1518 1959 1478 11434 12791 8038 12745 38000 38000 22045 3099 1960 10565 14233 11367 10519 9470 6788 16283 8339 3451 321 1961 11141 12412 13508 14341 15161 15431 15884 12082 10844 5313 1254 2531 1695 1605 1962 17077 31794 18053 16716 13452 18126 15453 12633 12481 12328 12442 11954 3647 788 686 1963 17425 35660 35399 28504 18633 15554 12138 13217 9366 4294 2557 1964 24763 15373 16152 14790 7396 9588 8584 5009 5799 3150 485 1965 4530 17909 14360 11724 9431 20871 9785 974 5802 9176 7301 9902 2352 1966 315 10806 16923 12181 8248 11797 7268 1791 1222 862 1967 3642 19490 28939 16013 14234 38000 35808 15524 16962 5692 1126 1968 8376 19787 16467 \5634 14801 11676 9661 6356 4702 2811 449 237 1969 1970 1971 5568 35688 35364 33824 8903 11407 3442 1972 27681 15296 15377 15406 12819 8829 10424 11790 9910 10401 3558 2574 6945 2209 1973 9816 6856 11550 12493 2061 1974 933 5556 971 1975 8802 21320 18293 15834 13634 9088 8123 5931 3521 852 8114 6725 3852 1976 19324 11172 6286 1358 1977 6547 11546 13866 15193 11163 12222 11533 9627 9681 2375 3499 2711 455 1978 5605 9793 8765 7358 4460 295 511 1979 414 25583 26961 15705 14155 9530 6592 4496 2187 1980 15211 24268 27733 21070 27256 12238 10917 8887 3681 231 7092 845 1981 10948 36106 33034 35511 32820 37137 36610 23332 6858 3369 897 1982 7234 14711 17555 13150 6242 4101 2253 3305 2533 5451 14185 2962 1983 4202 8632 9995 10799 16210 14196 11310 15506 7653 709 441 4218711 850219 IIiIi. .... .... .... late April,the difference between the max~mum and minimum flows for a given week is less than a few hundred cfs.From early May to late October, differences in flow are greater. There is an almost certain probability that cone valve releases will occur during the initial years of Devil Canyon operation.Depending on the inflow cone valve releases may range from only a few thousand cfs to 38,000 cfs. The duration may be as short as a few weeks to as long as 15 weeks.This is presented in Table 3.4-3. Figure 3.3-15 illustrates the discharges at Gold Creek for each of the 52 weeks that wou ld be exceeded 6,50 and 97 percent of the time.There is little variability in weekly average flow for any given week between October and April.The week to week variation during this period is small and results from the gradually varying energy demand.In summer there is a substantial flow variation caused by the variation in flow.In dry years, Watana reservoir does not fill until late summer.Therefore,flow remains close to the minimum flow requirements during the summer months.Under high flow and average flow conditions,Watana reservoir fills much earlier.Once filled to elevation 2,185,Watana and Devil Canyon are operated essentially so that inflow equals outflow.Therefore,flow at Gold Creek will be similar to that occurring under natural conditions once Watana reservoir is filled to its normal maximum operating level of 2,185 feet.However, inflows ~n excess of approximately 31,000 cfs will be limited to discharges less than or equal to that amount by the capacity of the cone valves and powerhouse. Weekly average discharges at Sunshine and Susitna Station for the 2002 demand are provided in Table F-8.Weekly reservoir elevations for both Watana and Devil Canyon are provided in Table F-6 and F-7.Figures 3.3-16 through 3.3-19,present probability distributions of Watana water surface elevations for the first week of October,January,April and July.The figures show that in the early years of Watapa and Devil Canyon operation, Watana reservoir will rarely be drawn below elevation 2,120 feet and will almost always be filled annually.Devil Canyon reservoir will normally be 421863 850227 3-23 - between elevation 1445 and 1,455 feet Figures 3.3-20 and 3.3-21 show maximum, Watana and Devil Canyon reservoirs • to minimize temperature impacts. minimum and mean water levels at ..... 3.3.2.2 2020 Electrical Energy Demand Forecast - ..... - Weekly discharge and reservo~r levels based on reservoir operations studies for a 2020 electrical energy demand forecast of 8312 Gwh are presented in Appendix F hereto (Tables F-9 and F-IO). As the energy demand grows the usable energy from the project will likewise increase and result in greater discharges through the turbines at both Watana and Devi I Canyon.By the year 2020,the available energy from the project can be absorbed in the system.With-project flows in 2020 would therefore be indicative of project flows a few years before 2020 and after 2020. Watana turbine discharges and flow duration data for the 34 years of simulation are presented in Tables F-9 and F-22,respectively.Maximum weekly average Watana turbine discharge is 12,600 cfs and the minimum weekly average discharge is 4,000 cfs. The cone valve releases at Watana are much reduced in frequency,magnitude and duration when compared to the releases which could occur in the early years of both Watana and Devi I Canyon operation.There is a 40 percent chance that there will be a cone valve release from Watana in any given year.Releases will occur in August and September.Not only will the cone valves at Watana not be used to capacity,there is a 40 percent probability that if there is a cone valve release,the peak discharge during the release will be less than 6,000 cfs.A summary of cone valve releases at Watana is provided in Table 3.4-4. Maximum weekly average turbine discharge at Devi I Ganyon,as presented in Table F-10,will be 12,900 ds.Minimum weekly turbine discharge will be 1,900 cfs.This minimum discharge would occur only during a low flow event 421863 850227 3-24 - ..... - ..... - such as took place .in 1969.The average turbine discharge during tne November to February period will be about 10,000 to 11,300 cfs.Cone valve releases would occur in about 44 percent of the years as indicated 1n Table 3.4-4.Since Devil Canyon will normally be operated at a constant reservoir elevation of 1455,outflow is approximately equal to inflow.Therefore, when cone valve releases are required at Watana they are usually required at Devil Canyon.Cone valve releases will occur in August and September. With-project flows at Gold Creek are listed in Table F-lO.Table F-24 shows the percent of time that discharges at Gold Creek would be equalled or exceeded for each week of the year.Figure 3.3-22 illustrates the discharges for each of the 52 weeks that would be exceeded 6,50,and 97 percent of the time.In the winter period,flow is generally a few thousand cfs above the minimum flow requirements and a few thousand cfs below the maximum flow requirements for the entire historic record.In summer,during low flow years,discharge at Gold Creek is maintained at the minimum flow requirements.During average years,with-project flow at Gold Creek is about 1,000 cfs higher than the minimum requirements.During high flow conditions,with-project flow can approach 40,000 cfs. Because the drainage area between Devil Canyon and Gold Creek is about 36 percent of the drainage area between Watana and Gold Creek,the flow variations at Gold Creek caused by variations in intervening flow between Devil Canyon and Gold Creek wi 11 be much reduc-ed from that which could occur when Watana operates alone. Discharge data at Sunshine and Susitna Station for the 2020 demand are given in Table F-ll. Weekly reservoir elevations for both Watana and Devil Canyon are provided in Tables F-9 and F-IO,respectively.Figures 3.3-23 and 3.3-24 show maximum, mean and minimum reservoir levels for Watana and Devil Canyon,respectively. Figures 3.3-25 through 3.3-29 show Watana and Devil Canyon flows and water levels for the 34 years of simulation.Figures 3.3-30 through 3.3-33, present probability distributions of Watana water surface elevations for the 421863 850227 3-25 ..- !""", .... first weeks of October,January,April and July.With a mature system, Watana reservoir will normally be drawn down to between elevation 2070 and 2085 feet 88 percent of the time.Annually,there is a 62 percent chance that the reservoir will be filled to between elevation 2,180 feet and 2,185 feet. Devil Canyon reservoir will normally be maintained at 1,455 feet,but in low flow years may be drawn down to provide the minimum weekly flow requirement at Gold Creek• 421863 850227 3-26 f""", .... .- .... - I""" I .... 3.4 WATER QUALITY The License Application discusses the effects of construction and operation of the project on the water quality of the Susitna River.The following parameters were evaluated:water temperature,ice,bedload and suspended sediment,turbidity,vertical illumination,dissolved gases,nutrients, total dissolved solids,specific conductance,significant ions,total hardness,pH,total alkalinity,free carbon dioxide,total organic carbon, chemical oxygen demand,true color,metals,chlorophyll-a,bacteria and miscellaneous parameters such as pesticides,herbicides,uranium and gross alpha radioactivity.Only the water temperature,1ce,and dissolved gas parameters would be affected by the Case E-VI refinement to Case C. The Alaska Power Authority,at FERC's request,has made simulations of the reservoir and river,temperature and ice conditions for Watana operating alone and for Watana and Devil Canyon operating together.These simulations considered several levels of projected energy demands and various hydrological and meteorological conditions using Case C flow requirements • The simulations were transmitted to FERC with the Power Authority's comments on the DEIS (Alaska Power Authority 1984a,1984b,1984c)and in a separate transmittal in October 1984 (Harza-Ebasco,1984). The Case C simulations refined and expanded the information presented in the License Application (Figures E.2.l71 E.2.185 and E.2.213 -E.2.222)' Also,the Power Authority had previously presented.a calibration of the DYRESM model (Harza-Ebasco,1984a)which refined and expanded the analysis in the License Application (Figures E.2.165 -E.2.171).[See Appendix C (this report)for current status of License Application Tables and Figures relative to Case E-VI.] The Power Authority has now made further simulations of reservoir and river temperatures and ice conditions to determine the effect(s)of the Case E-VI refinement to Case C.The new simulations provide nearly identical results as the simulations developed for Case C (see comparisons in Appendix G and Appendix H). 421863 850227 3-27 ..... .... .... I ,.... .... Because of the similarities in the results of the new simulations for Case E-VI,the Power Authority believes that its comments on the DEIS regarding the impact of construction and operation remain valid for Case E-VI flow conditions and that the simulations for Case C may be used to evaluate effects of Case E-VI. Additionally,the Power Authority has checked the reservoir operations for Case E-VI and has determined that the potential for developing detrimental levels of gas concentration in excess of naturally occurring levels due to project operation is less than or equal to the potential with Case C. The remainder of this section presents discussions of the results of the analyses,first for Watana operating alone,and then for Watana and Devil Canyon operating together. 3.4.1 Watana Operating Alone 3.4.1.1 Reservoir Temperature and Ice Reservoir temperatures and ice cover were simulated for Case E-VI using DYRESM.The projected energy demands are for the year 2001 and the hydrological and meteorological data are from the period November 1980 to September 1982.This period represents a high flow year (1981)followed by an average flow year (1982).These simulations provided the upstream boundary conditions for all river temperature and ice simulations described below. Simulations for both Case C and E-VI (see Appendix G,Exhibits 1 and 2)used the policy of releasing water having temperatures as close to natural as possible,as set out in the License Application (p.E-2-119).The simulations for both cases result in similar outflow temperatures,similar ice thicknesses and simi lar freezeup and melt-out dates.Outflow temperatures are generally within a few tenths of a degree except for a few short periods where the difference is as much as one degree. .....421863 850227 3-28 - - The most significant difference occurs in early July of the 1982 simulation. The Case E-VI simulation results in about 5°C cooler outflows for about one week.This difference results from somewhat lower reservoir water levels due to higher releases early in the summer with Case E-VI compared to Case C.The reduced reservoir levels cause the third level of the multi-level intake to be used for Case E-VI rather than the second level for Case C. Water at the third level is somewhat colder than at the higher level. For the summer period after the first week in July,the release temperatures with E-VI are approximately O.soC warmer than for Case C.The effects of these differences are reduced downstream. 3.4.1.2 River Temperatures,Open Water River temperatures were simulated for Case E-VI using SNTEMP.Again,the projected energy demands are for the year 2001;and the hydrological and meteorological data are for the period May 1981 to September 1982.The simulation for the period Novem~er 1981 to April 1982 was used to define the upstream boundary of the river ice run.The results of the simulations are shown in Appendix G,Exhibit 3.The results of a similar simulation using Case C flow requirements are shown in Appendix G,Exhibit 4.Comparisons of simulated temperatures for these two runs at river miles 100,130 and 150 are shown in Appendix G,Exhibit 5. As can be seen from the comparisons of the two runs the temperature differences are larger at river mile 150 and diminish with distance downstream.The temperature differences between Case C and Case E-VI are generally within a few tenths of a degree (OC)except for a one week period in 1982 in which there is a difference of 5°C at the dam.Note,that even for this large a difference in reservoir outflow temperatures,the difference at river mile 130 is only about 1°C.This indicates the importance of climate conditions to river temperatures.Although the Case E-VI temperature is slightly colder for this one week,it is slightly warmer for the next few weeks. -421863 850227 3-29 ...... .- 3.4.1.3 River Ice River ice conditions were simulated for Case E-VI using ICECAL.The projected energy demands are for the year 2001 and hydrological and meteorological data are for the period November 1981 to Apri I 1982.The results are shown in Appendix G,Exhibit 6.The Power Authority's transmittals to the FERC (Alaska Power Authority 1984c and Harza-Ebasco 1984b)did not·contain a similar simulation for Case C flow requirements. Therefore,for this transmittal,a river ice simulation for Case C flow requirements has also been made and is presented in Appendix G.Exhibit 7. A comparison of the two runs is shown in Appendix G,Exhibit 8. As can be seen from the comparison of the runs.the Case E-VI flow requirements do not significant ly affect the results.The progression of the ice front.its location versus time.and the maximum water levels are all similar.The simulation for Case E-VI shows generally lower water levels (one to four feet)downstream of river mile 123.Upstream of river mile 123,however,water levels are generally one to two feet higher.This is not considered significant since it does not result in a significant difference in the number of side sloughs which might be affected by overtopping due to staging.The differences appear to be the result of slightly different reservoir outflow temperatures and discharges for Case E-VI than for Case C,which causes some differences in ice accumulation and I staging.With Case E-VI the river ice cover is simulated to melt out approximately 10 days earlier than with Case C. 3.4.1.4 Dissolved Gases As discussed in the License Application (p.E-2-132 and Table E.2.50).the design for the Watana Dam includes cone valves /which will be used to release all floods with return periods of 50 years or less.The use of cone valves to pass flows ~n excess of energy and minimum flow requirements will minimize the potential for gas concentrations to exceed naturally occurring levels downstream of the project.As can be noted from Appendix E,Tables 5 ....421863 850227 3-30 and 8,and-Tables 3.4-1 and 3.4-2,the cone valve capacity of 24,000 cfs is never exceeded.Therefore,the spillway would not be operated and detrimen- tal levels of gas concentrat ion would not be expected to exceed naturally occurring levels as a result of project operation. Flood routing studi es have also confirmed that the SO year flood for the period July-September can be stored and released without operating the spillway. .... 3.4.2 Watana And Devil Canyon Operating ..... 3.4.2.1 Reservoir Temperature And Ice Reservoir temperatures and 1ce cover were simulated for Case E-VI using DYRESM.The projected energy demands are for the year 2002 with hydrological and meteorological data from the period November 1980 to September 1982.This period represents a high flow year (1981)followed by an average flow year (1982).These simulations provided the upstream boundary conditions for all river temperature and ice simulations described below • Simulations for both Case C and E-VI (see Appendix H,Exhibits a-I and H-2) used the policy of releasing water having temperatures as close to natural as possible,as set out in the License Application (p.E-2-119).The simulations for both cases again result in simil~r outflow temperatures, simi lar ice thicknesses and simi lar freezeup and melt-out dates.Out flow temperatures are generally within a few tenths of a degree except for a few short periods. June 1981 E-VI outflow temperatures are approximately 1°C cooler than Case C.Early to mid-July 1982 outflow temperatures are similar to 1981 temperatures but average 2°C cooler than Case C.The E-VI temperature in the second week of July 1982 1S 4.5°C cooler than for Case C.The drop in outflow temperatures in mid-July which is common to both Case C and Case E- 421863 850227 3-31 Table 3.4-1 ....SUSITNA HYDROELECTRIC PROJECT WATANA FIXED CONE VALVE OPERATION 1996 SIMULATION ~ Week of Week of Duration First Maximum of Maximum Powerhouse Total ~Year Release Release Release Release Flow Release Weeks ds ds ac-ft 1950 1951 June 17 Sept 23 2 4,252 7,769 70,900 1952 ....1953 1954 1955 July 29 Aug 26 9 12,187 7,118 488,000 1956 Aug 12 Aug 12 7 12,923 6,756 725,000-1957 Sept 9 Sept 16 3 7,361 7,647 229,000 1958 Aug 26 Aug 26 1 204 7,203 2,830 1959 Aug 26 Sept 2 5 13,636 7,317 268,000....1960 Sept 23 Oct 1 2 1,558 8,220 32,600 r 1961 Aug 26 Aug 26 1 38 7,147 528 1962 July 8 July 29 12 15,409 6,642 1,220,000 1963 Aug 5 Aug 19 8 10,955 6,870 477 ,000-1964 July 22 Aug 19 5 5,832 6,855 173,000 1965 Sept 9 Sept 23 4 10,546 7,782 344,000 1966 1967 Aug 12 Aug 12 6 24,000 6,797 1,070,000 1968 Sept 2 Sept 2 2 1,731 7,288 47,000 1969 July 1 July 22 2 192 6,853 3,600 1970 1971 Aug 26 Sept 2 5 11,857 7,313 336,000 1972 July 22 Sept 9 9 8,380 7,477 263,000 1973 July 8 July 15 5 734 6,765 26,100 1974 1975 Aug 26 Sept 9 5 8,372 7,477 365,000 1976 July 29 Aug 19 5 1,135 7,069 61,300 1977 Aug 12 Sept 9 6 4,766 7,469 190,000 1978 1979 June 17 June 17 1 3 7,470 40 1980 Sept 16 Sept 16 3 3,638 7,646 94,300 1981 Aug 12 Aug 19 7 23,911 6,892 788,000 1982 1983 July 15 July 15 2 225 6,684 4,420 .... 421561/TBL 850219 3-32 -, Table 3.4-2 SUSITNA HYDROELECTRIC PROJECT WATANA FIXED CONE VALVE OPERATION 2001 SIMULATION Week of Week of Duration First Maximum of Maximum Powerhouse Totalr--Year Release Release Release Release Flow Release Weeks cfs cfs ac-ft -1950 1951 1952 - 1953 1954 1955 Aug 26 Sept 2 5 9,795 8,126 '299,000 1956 Aug 12 Aug 19 7 8,526 7,647 563,000 ~1957 Sep 16 Sept 23 2 5,780 8,635 108,000 1958 1959-1960 Oct 1 Oct 1 1 628 9,128 8,720 1961 1962 July 22 July 29 10 14,648 7,403 1,110,000 1963 Aug 19 Aug 26 5 9,798 7,891 350,000 1964 Aug 26 Aug 26 2 2,013 7,874 39,000 1965 Sept 16 Sept 23 3 9,682 8,646 207,000 1966 ~1967 Aug 19 Sept 2 5 15,370 8,141 641,000 1968 1969 1970 1971 Aug 26 Sept 2 4 11 ,040 8,130 291,000 1972 Sept 9 Sept 16 2 3,201 8,485 47,600 ~1973 1974 1975 Sept 9 Sept 16 3 6,353 8,494 205,000 1976 Aug 12 Aug 19 3 326 7,878 10,600 ,....1977 Sept 16 Sept 23 2 1,254 8,623 34,400 1978 1979-1980 1981 Aug 12 Aug 19 6 23,121 7,682 720,000 1982 1983 -421561/TBL 850219 3-33 VI is a result of the fi 11ing of the reservoirs and the need to release ~, ro- I excess flows through the outlet works.Water temperatures at the outlet - - works intake are cooler than at the power intakes. The differences between the Case E-VI and Case C temperatures are a result of the higher minimum flow requirements for Case E-VI ~n June and July. These requirements are met by a combination of powerhouse discharges and outlet works releases from Devil Canyon Dam.During this period Watana Reservoi r is genera 11y bei ng fi 11ed.The two reservoirs can meet the flow requirements by being operated in different manners: 1.While Watana reservoir is being filled;meet the m~n~mum flow requirements as much as possible from Devil Canyon reservoir storage.This will result in lowered Devil Canyon water levels. Release only as much water from Watana as needed to keep Devil Canyon water level at the minimum operating level (elevation 1405)• a.Meet energy requirements by generat ing power from required Watana flows.Remaining energy requirements to be supplied by Devil Canyon flows,or b.Meet energy requirements by generat ing power from required.... Devi 1 Canyon flows.Remaining energy requirements to be supplied by Watana flows. 2.Meet the minimum flow requirements from Watana storage and operate Devil Canyon in a "run of river"mode,keeping Devil Canyon reservoir water level above the upper intake. a.Meet energy requirements by generating power from required Watana flows.Remaining energy requiremeQts to be supplied .....421863 850227 by Devil Canyon flows,or 3-34 ,... - b.Meet energy requirements by generating power from required Devi 1 Canyon flows.Remaining energy requirements to be supplied by Watana flows. Policy 1 is more e~ergy conservative than Policy 2 since Policy 2 results in releases from Watana prior to Watana reservoir being filled.Policies la and 2a are also more energy conservative than lb and 2b since lb and 2b result in releases from Watana which do not generate power.Policy 2 results in higher outflow temperatures than Policy 1.With Policy 1 there is a two to three week period,as Devi 1 Canyon water levels are being reduced,when the lower level of the Devil Canyon power intake must be used. Water temperatures at this level are approximately 1°C cooler than would be available if the water level were kept higher.Policy la would result in a Devil Canyon water level below E1.1445 and operation of the lower level intake approximately every other year.Policy 2b would force Devi 1 Canyon water level to be above El.1445 at all times. Policy 2b results in the warmest possible outflow temperatures and was used in reservoir operation simulations and reservoir temperature simulations for 2002 energy demands. As system energy requirements increase,Watana reservoir will be drawn down further in winter and will fill later in the summer.Less water will be released through the outlet works,and more water through the powerhouses. Thus,out flow temperatures would increase for all the policies discussed above.Additionally,with the increase in energy demands.Case E-VI flow requirements will be met by powerhouse releases at Devil Canyon.Additional energy will be generated at Watana,and this water will tend to keep the Devil Canyon water level above the upper level intake.Temperature differences between the policies will be reduced.In the 2020 Simulation Policy la results in June-July Devil Canyon water levels below El.1,445 in only 4 of the 34 years simulated.Therefore,for 2020 energy demands, Policy la was adopted for reservoir operation simulations. -I 421863 850227 3-35 r - - ..... 3.4.2.2 River Temperatures,Open Water River temperatures were simulated for Case E-VI using SNTEMP.The projected energy demands are for the year 2002,and hydrological and meteorological data are for the period May 1982 to September 1982.The simulation for the period November 1981 to April 1982 was used to define the upstream boundary of the river ice run.The results of the simulation are shown in Appendix H,Exhibit H-3.The results of a similar simulation using Case C flow requirements are shown in Appendix H,Exhibit H-4.Comparisons of simulated temperatures for these two runs at river miles laO,130 and 150 are shown in Appendix H,Exhibit H-5. As can be .seen from the comparisons of the two runs the temperature differences are larger at river mile 150 and diminish with distance downstream.The temperature differences between Case C and Case E-VI are generally within a few tenths of a degree COC)except for the periods noted in Section 3.4.2.1. 3.4.2.3 River Ice ICECAL was used to simulate r~ver ice conditions for Case E-VI flow require- ments.The projected energy demands are for the year 2002,and data are for the period November 1981 to April 1982.The results are shown in Appendix H,Exhibit H-6.A river ice simulation for the same conditions but using Case C flow requiremen.ts ~s presented in Appendix H,Exhibit H-7.A comparison of the two runs is shown in Appendix H,Exhibit H-8. As can be seen from the comparison of the runs,the Case E-VI flow require- ments do not significantly change the results.The progression of the ice front,its locat;ion versus time,and the maximum water levels are all similar.The number of side sloughs which might be affected by overtopping due to staging is similar.Slough 8 would be overtopped for Case C but not for Case E-VI.The differences appear to be the result of slightly different reservoir outflow temperatures and discharges for Case E-VI than fbr Case C.which causes some differences in ice accumulation and staging. 421863 850227 3-36 - .- 3.4.2.4 Dissolved Gases As discussed in the License Application (p.E-2-132 and Table E.2.58)the design for Watana and Devil Canyon Dams includes cone valves which will be used to release all floods with return periods of 50 years or less.The use of cone valves to pass flows in excess of energy and minimum flow require- ments will minimi~e the potential for gas concentrations to exceed naturally occurring levels downstream of the project.As can be noted from Appendix F,Tables 5 and 8,and Tables 3.4-3 and 3.4-4,the Watana and Devil Canyon cone valve capacities of 24,000 cfs and 38,500 cfs are never exceeded.Therefore,the project spillways would not be operated and detrimental levels of gas concentrations would not be expected to exceed naturally occurring levels as a result of project operation. Flood routing studies have also confirmed that the 50-year floo·d for the period July-September can be stored and released from the project reservoirs without operating the spillways. - 3.4.3 Refinement to Reservoir and River Temperature and Ice Studies -: - The reservoir and river temperature and ice simulations transmitted to the Federal Energy Regulatory Commission (FERC)with the Alaska Power Authority's comments on the Draft Environmental Impact Statement (DEIS) contained simulations for the winter period October 1976 to May 1977. Reservoir simulations for this period utili~ed climatological data from the Federal Aviation Administration Weather Station at Talkeetna because the National Weather Service station at Summit,used for simulations in the period November 1970 to October 1976,was closed in October 1976.After the initial simulations were made,an examination showed that the wind speeds recorded for Talkeetna for this period were not similar to typical -wind speeds at Summit and Watana.A sensitivity run of the model showed that the use of the Talkeetna wind speeds resulted in somewhat colder reservoir outflow temperatures and thus a more extensive downstream river ice cover than if more accurate wind speeds had been used. -421863 850227 3-37 Table 3.4-3 SUSITNA HYDROELECTRIC PROJECT DEVIL CANYON CONE VALVE OPERATION 2002 SIMULATION Week of Week of Duration Maximun Watana First Maximum of Maximum Powerhouse Total Release Year Release Release Release Release Flow Release During Period Weeks cfs cfs ac-ft cfs -1950 Aug 05 Aug 12 4 10,898 9,313 330,000 18,160 1951 Aug 05 Sep 02 8 18,816 9,438 1,024,000 24,000 1952 Ju1 15 Ju1 29 11 33,443 1,087 1,385,000 24,000 ,.,...1953 Ju1 01 Ju1 29 12 14,846 9,159 1,406,000 20,931 1954 Ju1 22 Ju1 29 9 20,574 8,436 1,271,000 24,000 1955 Ju1 08 Aug 26 11 34,184 0 1,967,000 24,000 1956 Ju1 01 Ju1 15 13 24,721 5,460 2,564,000 24,000.....1957 Ju1 08 Ju1 22 12 15,756 8,825 1,695,000 22,198 1958 Ju1 08 Ju1 29 8 35,626 0 1,391,000 24,000 1959 Ju1 15 Aug 19 9 38,000 0 2,055,000 24,000 1960 Ju1 29 Sep 09 10 16,283 10,303 1,271,000 22,570 1961 Jun 24 Aug 05 14 15,884 9,177 1,855,000 23,083 1962 Jun 17 Jun 24 15 31,794 2,108 2,753,000 24,000-1963 Ju1 01 Ju1 08 11 35,660 0 2,684,000 24,000 1964 Jun 24 Jun 24 11 24,763 4,843 1,546,000 24,000 1965 Jul 08 Aug 12 13 20,871 7,840 1,728,000 24,000 1966 Ju1 15 Jul 29 10 16,923 9,166 994,000 22,511 r-'1967 Jul 08 Aug 12 11 38,000 0 2,721,000 24,000 1968 Jun 24 Jul 01 12 19,787 8,036 1,545,000 24,000 1969 6,123 1970 -3,390 1971 Jul 29 Aug 05 7 35,689 0 1,869,000 24,000 1972 Jun 17 Jun 17 14 27,681 3,698 2,134,000 24,000 1973 Aug 05 Aug 26 5 12,493 9,767 596,000 20,593 1974 Aug 26 Sep 02 3 5,556 10,030 104,000 13,996 1975 Ju1 01 Ju1 08 13 21,320 7,116 1,727,000 24,000 1976 Aug 05 Aug 05 4 19,324 6,406 531,000 24,000.....1977 Jun 24 Ju1 15 13 15,193 8,812 1,537,000 21,740 1978 Jul 22 Jul 29 7 9,793 9,142 512,000 17,979 1979 Ju1 08 Jul 22 9 26,961 3,907 1,470,000 24,000-1980 Ju1 01 Ju1 15 12 27,733 3,852 2,220,000 24,000 1981 Jul 08 Aug 12 11 37,737 0 3,581,000 24,000 1982 Ju1 08 Ju1 22 12 17,555 8,831 1,305,000 23,533 1983 Ju1 08 Aug 05 11 16,210 9,178 1,387,000 22,829..... ..... i .-, 421561/TBL 850219 3-38 -421561/TBL 850219 3-39 .... .... .... I"""' I ! ... For this reaSbn the reservoir and river temperature and ice simulations for the period October 1976 to May 1977 have been refined.Typical wind speeds from the Summit station were used to replace the Talkeetna data • The refined reservoir and river temperature and river ice runs are included in Appendix 1. 421863 850227 3-40 - 3.5 IMPACT ASSESSMENT Case E-VI is designed to reduce environmental impacts of project operation as compared to flow cases designed specifically for power generation.Case E-VI can not,however,mitigate all impacts by flow release alone,so 3.5.1 addresses the principal potential impacts of Case E-Vl flow requirements on each life Sl:age of the five Pacific salmon species.The resident evaluation species are treated separately in Section 3.5.2. ,.... further impact evaluations and mitigation planning are necessary.Section 3.5.1 Life Stage Impacts -Pacific Salmon Upstream migration Adult salmon migrate up the Susitna River toward spawning areas throughout the summer.The 9,000 cfs summer minimum flows will ,.... provide sufficient conditions for upstream migration of adults. Spawning Less than 15 percent of the salmon using the Susitna River System the salmon that spawn in the Middle River Basin use tributary habitats outside the influence of mainstem discharge.The major spawning habitat most sensitive to changes in mainstem discharge are the side sloughs used by chum and sockeye salmon.Mainstem flows affect spawning success in side sloughs by influencing total usable area within the sloughs.groundwater discharge,and access past critical reaches of the stream. ,...., actually spawn in Middle River habitats (ADF&G 1984a).Most the Access into the major spawning sloughs (8A,9.9A,11 and 21) would be restricted under Case E-Vl flows.Analysis based on observed spawning use provides an estimated reduction of-approximately 50%of side-slough spawning due to access restriction at 9,000 cfs (see Power Authority Comment on DElS No. AQR072).However,considering the restricted access together with reduced area and flow within the sloughs,a worst case assumption 421863 850227 3-41 - - .... - .... i 421863 850227 of 100%lo'ss of side-slough spawning habitat without further mitigation is used for this evaluation. Juvenile Rearing Chinook salmon juveniles rear in both clear and turbid water habitats.Substantial rearing occurs in both tributaries and side channels (ADF&G 1984b).Through the summer.densities generally decrease in tributaries and increase in side channel habitats. Population densities in side sloughs are relatively low during the summer but increase markedly during September and October. Tributary habitat would not be impacted by the altered mainstem flows.Case E-VI flows would,however,reduce the quantity of available existing rearing habitat at side channel sites presently used by chinook by approximately 25%. Chum salmon rearing 1S essentially limited to tributaries and side sloughs during the early summer (May to early June).Highest population densities during late June and July occur in upland sloughs and tributaries.Essentially all the juvenile chum have moved downstream,out of the Middl e River,by the end of July. Case E-VI flows would not impact rearing habitat in tributaries and upland sloughs.Chum salmon use mainstem sites mostly for short-term holding and rearing during downstream migration.Case E-VI flows would not decrease the availability _of the low velocity,mainstem backwater sites as presently used by chum. There would,however,be a decrease of chum rearing habitat 1n side sloughs.Most of the decrease would be due to a reduction or elimination of overtopped conditions in side sloughs during May / and June.Decrease of habitat could be as great as 50%at the sites utilized under natural flow conditions • Sockeye juveni les rear predominantly in natal side sloughs during the early summer and then move mostly to upland sloughs by July. With-project flows are not expected to affect upland slough 3-42 -, .... habitats.The responses of weighted usable area for sockeye and chum are similar for side slough rearing habitat.Therefore, reduction of sockeye rearing habitat would also be approximately 50%• Coho salmon Impacts due habitats. rear mostly in tributaries and upland to project operation are not expected sloughs. 1n these ,..- -421863 850227 Pink salmon juveniles move rapidly from their natal tributaries to Cook Inlet.The mainstem and associated habitats are apparently used only for migration corridors so project flows would not impact pink salmon rearing. Downstream Migration Downstream movement of salmon juveniles occurs throughout the summer (ADF&G 1984b).Chum,pink and age 1+chinook salmon migrate toward Cook Inlet during the early summer and are out of the Middle River reach by July.Sockeye,coho and age 0+chinook move gradually downstream throughout the summer.Most of this movement is associated with rearing and gradual relocation into available rearing and overwintering habitat. Some of this downstream movement 1S influenced by mainstem discharge (ADF&G 1984b).Increasing discharge during flood flows can act as a stimulus to initiate seaward migration,especially during the early summer.Flood flows later in the summer,when juveniles are rearing or seeking alternative habitat sites,can cause dislocation from preferred rearing areas.Project operation will reduce the frequency and amplitude of flood events in the Middle River.This impact is not expected to significantly affect seaward migration.Factors other than flow,such as increasing day length,water temperature and physiological condition also trigger migrat ion.In addition,increased turbidity,and local run-off could also serve to stimulate migration. 3-43 - 1""'" I 3.5.2 Life Stage Impacts -Resident Evaluation Species Arctic Grayling The major uses of sensitive habitats by arctic grayling are overwintering 1n mainstem habitat and rearing at tributary mouths. With-project conditions wi 11 increase the availabi lity of clearwater habitats in general,including tributary mouth habitat (Trihey 1984).More stable with-project flows under Case E-VI will also improve the quality of tributary mouth habitat. Therefore,no adverse impact during the ice-free period 1S expected. Arctic grayling overwinter 1n mainstem areas.Major movement out of the tributaries occurs 1n September and the fish then move downstream to locations where they remain for the rest of the winter (ADF&G 1983).Habitat requirements for overwintering are not entirely understood but the grayling probably seek stable, deep,low velocity sites relatively free from radical changes due to ice processes.With-project flows will be greater during the winter than natural flows.Therefore,the total area of mainstem, side channel and side slough habitat types will be greater under with-project winter flows and the availability of deep,low velocity sites should also increase.The upstream progression and duration of an ice cover in the Middle River will be reduced under project operation (Harza-Ebasco 1984a).This should further improve overwintering conditions for grayling. Turbidity levels will be higher during the winter under project operation.This may limit the use of mainstem sites since grayling show a preference for clearwater habitats.With-project winter turbidity was estimated to be approximately 10-20 NTU 's which is at the lower end of the range experienced annually under natural conditions (0-1,000 NTU's;Lic.App.,Exhibit E,Vol.SA, pp.E-2-30 and E-2-13l).The expected turbidi ty is within the range that grayling experience in the mainstem and tributaries 421863 850227 3-44 fl;'IIII'l!ll -. - - - ~-I 421863 850227 during the early sU1lllller when snowmelt is a large contributor to surface runoff.Therefore,grayling may be able to successfully tolerate the expected with-project turbidity.In addition,the quantity of clearwater habitat in secondary channels (side sloughs and side channels)will be greater under with-project flows.This results from increased head due to higher flows and ice staging ~n the mainstem which increases groundwater and intragravel flow to peripheral habitats. Thus,it is expected that Case E-VI flow constraints will provide habitat of sufficient quantity and quality (stability)to maintain existing grayling production. Rainbow Trout The major uses of sensitive habitats by rainbow trout are similar to those of Arctic grayling (Table 2.2-3).Rainbow also appear to be less dependent on clearwater habitats and are found more frequently in side sloughs than grayling (ADF&G 1984b). Therefore,rainbow trout should be more tolerant of with-project winter turbidity levels and are more likely than grayling to utilize available clearwater sites to overwinter. The general increase of clearwater habitat (especially tributary mouth)during the sU1lllller and the maintenance of sufficient conditions for overwintering under Case E-VI flow constraints should result in maintenance of rainbow production at levels equal to or higher than natural levels. Dolly Varden The primary use of sensitive habitats by Dolly Varden is overwintering ~n the mainstem.Details regarding their habitat preferences are not well known but they probably seek sites similar to arctic grayling and rainbow trout.Dolly Vard.!'!n are found in turbid river systems (McPhail and Linsey 1970)so with- project winter turbidity should not limit their use of mainstem 3-45 .- - and peripheral habitats.Project operation under Case E-VI flow constraints will provide sufficient habitat to maintain production of Dolly Varden at present levels • Burbot Burbot use mainstem habitat throughout the year and for all life history stages.They seem to prefer turbid water during the ice- free season since they are rarely captured 1n the clearwater habitats (ADF&G 1984b).They also show a preference for backwater sites in the mainstem and at slough mouths.Spawning occurs in January although sampling results indicate that little spawning occurs in the Middle River (ADF&G 1984b). Project operation under Case E-VI constraints will result in lower,more stable summer flows than natural condit ions.Summer flows of approximately 9,000 cfs will produce an increase in habitat with side slough and associated slough mouth characteristics (Trihey 1984).The lower summer flows will also increase the number of sites characterized as low velocity, backwater areas.Therefore,with-project summer conditions should provide sufficient habitat to maintain production of burbot at present levels. Higher water surface elevations caused by increased flows and ice staging during the winter will increase the number of secondary channels that receive flow (Harza-Ebasco 1984a).The increased complexity of wetted channels wi 11 increase the number and areal extent of backwater sites in the mainstem and at slough mouths. Therefore,a sufficient quantity of habitat will be available for burbot during the winter. 421863 850227 Habitat quality turbidity.Burbot the relatively low will be most affected by increased winter are very tolerant of high turbidity levels so levels expected with project operation will not 3-46 affect their survival.Increased turbidity might be expected to affect spawning by limiting visual cues and orientation for spawning behavior;however,burbot are nocturnal spawners and typically spawn under an ice cover (Scott and Crossman,1973).-i Vision must be of little or no importance to burbot spawning. Thus project operation under Case E-VI constraints will not affect burbot production. 3.6 MITIGATION Project impacts would be minimized largely through timing and control of flow releases by adopting the environmental flow requirements in Case E-VI. Without environmental restrictions ("p-1 flows",Harza-Ebasco 1984d,p.4.) flows could fall below 9,000 cfs during June through August in approximately 75%of the years of operation.Mean monthly summer flows could be as low as 4,500 cfs in some years.This would result in total loss of most of the mainstem and side channel rearing habitat presently used by chinook and chum salmon juveniles.Case E-VI flows would minimize this impact by maintaining 75%of the existing side channel rearing habitat.The residual 25%loss of side channel habitat and the loss of chum and sockeye rearing habitat 1.n side sloughs would be rectified by habitat replacement at the more stable, lower flows (relative to natural flows)under Case E-VI. -The impact assessments discussed above (section 3.5)are b.ased on impacts to habitat sites that are now available and used under natural flow conditions. The assessments did not consider the addition of new habitat sites with appropriate characteristics and qualities that would become available at the lower,more stable flows resulting from Case E-VI operation.A case in point is the increase in side channel rearing areas for chinook salmon.The quantity of side channel ,rearing habitat depends largely on channel complexity,and there is relatively little of this habitat available at bank full flows.The habitat quantity increases as flows decrease,and the flow channels become more complex until a point is reached when flow is reduced to a single thalweg channel.Channel complexity favorable for side channel 421863 850227 3-47 - rearing ~s much greater at the lower,summer operational flows (Case E-VI) of 9,000 to 12,000 cfs,than at mean summer natural flows of approximately 23,000 cfs. Overall,the quantity of side channel as well as mainstem rearing habitat for both chinook and chum salmon is expected to increase over natural conditions during project operation using Case E-VI flow requirements. Increased flow stability and decreased turbidity are expected to improve habitat quality and augment rearing potential in the Middle River. Case E-VI minimum flow constraints during late August and early September will minimize impacts of the project on chum and sockeye spawning.However, the loss of side slough habitat for chum and sockeye salmon spawning will need to be rectified by structural modification of existing sloughs. Details of these activities are given in a report entitled "Interim Mitigation Plan for Chum Spawning Habitat in Side Sloughs of the Middle Susitna River"(Woodward Clyde 1984). The results of the Case E-VI mitigation measures are compatible with mitigation policies and objectives presented in the License Application (Ex. E,Chpt.3,p.E-3-l47).The measures provide habitat quantity and quality sufficient to maintain naturally reproducing populat ions.All signi ficant impacts are minimized or rectified. -421863 850227 3-48 1 11I ]-I ]1 J 1 1 1 1 1 I ) ENVIRONMENTAL.FLOW REQUIREMENTS CAS E E n WATANA OPERATION--1996 DEMAND 4670GWH 50.000 ii'i ,ii'"i . -------+----- o 10,000 -40,000 I I I I I I I I I I NOTE 1.DI8CHAftGE FOft SUSITNA RIVER AT GOLD CM!EK 2.PERCENT OF TIME PROJECT FLOW 18 EQUALLED OR EXCEEDED IN A GIVEN WEEK.CURVES ARE _ .ASED ON 34 YEARS OF AVERAGE WEEKLY FLOWS. 30,000 3.MAINTENANCE OF 75" CHINOOK SALMON, 81DE CHANNEL REARING HABIT A T EXCEPT LOW FLOW YEARS 20,000 t--i---t---t----l--~jf!!pt~!. ~~~~~~~~~~~~~~~~~~~ ~-. -n~i~",<,,:r}r I LI ; .-.... (/) LLo w"-' I~UJ CJa: c( :t:oen-c JAN fl.MAR APR MAY JUN JUl AUG SfP OCT NOV DEC HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY I ]I ') ~ WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON OCTOBER 1 WATANA OPERATION 100 I I , I I I I I I I I I I I I I I I I 1 90 I I I I I I I I I I I I I I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND .OF 4670 GWH<IN THE YEAR 1996 80 I I I I I I I I I I I I I I I I I I I 1 1 1 1 1 1 1 I 70,..... ~ W Z I I I I I I I I I I I I I I I I I I ,I I ,I I e;:;:!:;:;:: I W\Jl 00a:60 W Q...... >-50,~I T r r I I I I I I I I I I 1 ,I T r-I I I I I:;:;~;~ ~ iii<~40 f 30 201----1---I +------}-------!---l----.+-+----I I I I I I I -I-I !.J--+---+---~-- 10 I I +--+-+---f---t----t-+----r-+------+---I--------jf---------+-1---+--+----+----I--1-4~-1--1 OL.____l~--.l._...L_...L_..L.._l_____l~--l._...L_...L_..L.._l_____l_~:;;;;:;;;;~_...L-...L..-L.____l:::m;i!2iIl2i2ii_~i:ml:iZZ:m;:;~~>M.__J 2060 2070 2080 2090 2100 2110 2120 2130 2140 2150 2160 2170 2180 2190 WATANA RESERVOIR ELEVATION (fT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY 01 G) w W I\:> 1 )]I WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JANUARY 1 WATANA OPERATION 100 90 80 '1 C)2130 2140 2150 2160 2170 2180 2190 NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 4670 GWH"IN THE YEAR 1996 ~ ~::~:~I':::'(.'*:"~**~i~f~~*'"~••:-0:••:'',:Jlt~I'.~~';:..s~~:~f.:#:~~~~~~~:~::::. :~;::-=*::.,~~",~~.." tii1f"=........-." I -------------'------ 11"1::~*;~ ::-;*;:~::~:.:*:::::$'$...:~t=i:~:.-r---"--------.~ I ::i:f:~i~:'i~1 liil.~...,~>:iit~~ r.;1~;~*1~•'l~~::t~~:::~.'..~;~~~~~~~*-T.~.:~~::$..~~::;:<o;::-:::.........o 2060 2010 2080 2090 2100 2110 2120 10 20 40 30 50 70 60 >-t: ...J iii-<~ f ...... ~zwoa:w 0... '-' VJ I l.J\ f-l WATANA ,RESERVOIR ELEVATION (FT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY w w w I J )-1 1 .)1 J 1 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON APRIL 1 WATANA OPERATION 100.I I I I I I I I I I I I I I I I I I i 90 I I I I I I I I I I I I I I I I I 1----4 NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND .OF 4670 GWH',N THE YEAR 1996 80 I I I I I I I I I I I I I I I I I I I I I I I I I I I W I \Jl N ,... ~ Z Woa:w Q........ "'"I I I I I I I I I I I I I I I I I I I 70 J I I 60 I I I I I I I I I I I I I I I I I I I I I I I I I I I >-t: ..J iii-< 2l f !'lol I I I I +I I I I I I I I I I I I I I I I I I I I j 40 I I I I I I I I I I I I I I I I I I I I I I I I I I I 30 I I I , I I I I I 20 I I -----,II--.--LI I I ,;i:~::::~:~:~I I I I I I I I I I -'+---+---+--~I I I ,o_o_o_o_a..••~~......,...... 'll C)219021602170 218021502140212021302 I 10 t!~~~~~~~1~il I I -I-I I I I I I I I +-- 2090 210020802070 10 .-----.-.-I : : o 2060 WATANA RESERVOIR ELEVATION (fT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY w w .p. 1 1 I -~1 ----1 1 )1 1 1 J WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JULY.1 WATANA OPERATION 100 j I I I I I I I I I I I I I I I I I I , 90 I I I I I I I I I I I I I I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND .OF 4670 GWH'IN THE YEAR 1996 80 I I I I I I I I I I I I I I I I I I I I I I I I'I I I 10,.... ~ W Z I W \Jl 0 60wa:w Q. ~ >-50t: -I (Q 4( ~40 f 30 20 I I I I I I I I I J I I tffii~:; 101 I I I I I I +I I I I OL-_L-......I_--l_-L_--L._--L_--L_--':O:ii:i:i::::::L-_..£i:ili:i:i:ili:l 2060 2010 2080 2090 2100 2'10 2120 2130 2140 ~;!: ~~~I~~I~I;~~~~~~~~~~~j 2150 2160 21.70 2180 2190 OJ CJ WATANA RESERVOIR ELEVATION (FT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY w W 01 .... FIG.3.3-6 WATANA RESEREVOIR WATER LEVELS WATANA ONLY OPERATING 2001 SIMULATION CASE E-VI 2200 ""'"2190 2180 ....2170 2160 2150.... 2140 2130 2120 .... 2110 2100 2090 2080 2070 2060 "'... I·I I I Iv-NORMAL MAXIMUM POOL EL.2185 1- '"/ "'-II~i\/\V f\\I V ~J \"I I~'\I I \1\,/I" 1\\~,/// t"-__ t'--..."\,/I",r\\// I ""'\f\/II i/",\I I "1\\1///'"1'-.1'-.,/ "",-\/I ~/, ""'-1/ /1'"'", "'"/ "-II NOTE:RESERVOIR LEVELS SHOWN ARE BASED ON MONTHLY....AVERAGE VALUES AND ARE PLOTTED AT MID-MONTH I I I I I MAXIMUM MEAN MINIMUM OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT HARZA-EBASCO SUSITNA JOINT VENTURE 3-54 ALASKA POWER AUTHORITY ..... FIG.3.3-7 U) ~>-~-a: 0 ~ ~ :;) 0 41( (D a:0'1 w-~ 0c. 41( :::.::: t.n (/) t'< IJl -I-41( wa: :::;) ~ Z W> ~ Z-o.., 41( Z f--UJ :::;) (/) oo (/) 41( CD W I 41( Na: 41( :I: ~ 01- lJ) lJ) (Jl- HJ 01- o lOm- .~ 01 0- .- Ir .J " J J ..I J -~ J 1"1 , ~1t8 J(Ja:s: J ..r " ". ~ ", J" j ../ ..J 1.00' .1 F"'" .... ::l: 0 ..J 1FUllWi cru..z~ ([0:: "'...\--cr~3:ffi.....(J) wcr J .~ ]I 1 '-1 -~l 1 ----]1 ."II'-" .D •WRTRNR SINGLE RESERVOIR OPERATION E-VI.LORD YEAR 2001 W I UI 0' 30000 ~20000 u ~zo -'LL I- ':Jo -J ([ 510000 ~ tIAlC 30603 , ~I ~I ~~,~l ~•VW M l.~~J ~r'\,,~~~~",~,~,1 - o •1950 1955 1960 1965 1970 1975 1980 1985 HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY "TI P ~c.u I CD "C~~-.I a I 1 'I -1 1 ~',--I•1I '-'11 ~11 ~I 1 1 ,c-1 WRTRNR SINGLE RESERVOIR OPERATION E-VI.LORD YERR 2001 2200 I Iii I I I I I-- ~2150 z 0......w l-I Ln ([-...J > W J W2100 wu <I LL 0:: :Jen 0::: W2050l- et :I 2000 -t I I I I I I I 1950 1955 1960 1965 1970 1975 1980 1985 -n is HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY '"w, (() l J 1 I ]~l )I•'&J J 1 I ENVIRONMENTAL..FLOW REQUIREMENTS CASE E n WATANA OPERATION-2001 DEMAND 5117GWH 50.000 pa ,;,r iii iii TI Q .. DECNOVOCTSEPAUGJULJUNMAYAP"MAftfE.JAN o NOTE 1.DISCHA"ae FOR SUSITNA RIVE"AT OOLD CREEK 2.PERCENT OF TIME 40.000 -i I I I I I I I I r PROJECT FLOW 18 EQUALLED OR EXCEEDED IN A GIVEN ........WEEK.CURVES ARE<n .......<>::><....<........BASED ON 34 YEARS LL :::.:.:.:>.....OF AVERAGE WEEKLYo........41-FLOWS. -...-.Vol 30,000 ...<.......:<':...1 .'~>..3.MAINTENANCE OF 7&" W ~:......::../.....<:...•CHINOOK SALMON C»"".•.•::..SIDE CHANNEL CC '...........<.:.REARING HA.ITAT c(i«)I><.EXCEPT LOW FLOW ::I:1:<..•.•••••.•'.<'.YEAR1So20.000 ....:(",:",/<,~•if (J)........>.:'.:::......:<:....:.::.:..........,..:.....: -MAX :......»..>:....., 0)·······ii<..•.•.•....···i:"'h=-I..•..~..·.····"·Ii; :«'".r···:..".:"~..<50"·.··J:~.:--:.,,:<....-:-":.<".<>":<"'~~.#ill.......·A .••.•..•.........<rf'w.~·!"'»>~£>. 10,000 I.·'·>l~~"~"'."·····r.4-~'·;.~·'"."'·-~~~"">"iJ .•...:..•....:_•.•:':<«>gl''Sli:....::...>:'.'.....'11 j.f:..:~~.'.</..,.::::. ::.: -.•...•'.:>'.•<.....'..It"""'L '!....:(.'<':7.....1.j<I:>::....._....:::»JI .'..::·:Y»..~ MIN L-I~DICATE~MIN '0-,LOW FL?W YEA"~ ~I 0 HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY -eel!----11 I I ---~1 I 1 J t ---. II -11 I 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON OCTOBER 1 WATANA OPERATION 100 I r I I I I I I I I I I I I I I I I I I 90 I I I I I I I I I I I I I I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND ,OF 5117 GWH'IN THE YEAR 2001 80 I I I I I I I I I I I I I I I I I I I I I 1 I 1 1 I I 70,.... ~ W Z I W ~.~0 60a:IW Q.. ~ >-50 --e I..Jm-<~40 ~I I I I I I I I I II I I I I I I I I I I I I I 111I11[~IIII! 30 20 I I I I I I I I I I I I I I , I I I I I I +---+---+-~-- 10 1---I----l'----1---+--+--+-+-+---f-----f----I---I----lf-'--1---+--+-+-+-+-+-~ o I I I ; I , , I II,.~- 2060 2070 2080 2090 2100 2110 2120 2140 2150 2160 2170 2180 2190 WA lANA RESERVOIR ELEVA liON (fl) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY OJ Cl w w i '--1 J J J )J '''1I j 1 J WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JANUARY 1 WATANA OPERATION II I II I I II I I II I I loor~I I I 901-+-/I /-----+---1 ,I I 1 1---1---1 I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND 'OF 5117 GWH-IN THE YEAR 2001 W I 0'o r-.. t- Zwoa:w 0.. ~ >-t- -l m ~ ~g: 80 I II-t---+---+I I l-t-/-f I I I I f l-l-----,i I I I I i I 70 I I 60 I --t--t-+-+-+.....---1 I I I I I I I r fir I I I I I I I 501'--+--+--l--t--1--1 I I I I I I I I I I I !I I I I 401 -<-r~-I-1--1 1 ~I I I I I ~I I I I I 1-----1 I 1 I I WATANA RESERVOIR ELEVATION CFT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY '::-~-:--:-:--'---'---'-T-~-.1.:111 2060 2070 2080 2090 2100 2110 2120 2\30 2140 2150 2160 2170 2180 301-1--- 20 .---.-._- 2190 ." CJ w (..l-I\.J I -~ JI ---11 !J 1 j ----'ll I WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON APRIL 1 WATANA OPERATION 100 I I I I I I I I I I I I I I I I I I • . 90 I I I I I I I I I I I I I I 1 I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND ,OF 5111 GWH'IN THE YEAR 2001 80 I I I I I I I I I I I I I I I I I I I I I I I I I i I 70.-. t- 1,.0.)Z I W 0'-0 60~.-tr W Il. ~ >-f>0t: -oJ iii <I( 40 1 1 I I~I I I 1:::~~i:3:::a ---+--~ ~ 30 201--~-----+-----f-------+---~----+---+I I I I I I I !-----+---+---+---1--c I I 101 I 1--I I I I I I I I I I --1-----1----l ---t-----i--- WATANA RESERVOIR ELEVATION (fT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY Ol--_L-_»:';':':':';';L-_.l.--_-""""=:t:;:;,;,= 2060 2070 2080 2090 2100 21 '0 2120 2130 2140 2.50 2.60 2170 2.80 2.90 OJ C) w w.-w 1 1 1 C C-l 1 -I I 1 -., j -11 J 1 1 -11 J J WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JULY 1 WATANA OPERATION 100 I I I I I I I I I 1 I I I I I I I I I 1 90 I I I I I I I I I I I I I I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND .OF 5117.GWH'IN THE YEAR 2001 W I 0'1 N r-. ~ Zwo 0: W ~ \oJ >-t: ..J iii« ~ f 80 1------j1---1--f--+--+-+-+-+-+--+--t--:I-----I----I--+-+-+-+-,---,----,r----,,----r--,----r--l 10 t--I I I I I I I I I I I I I I I I I I I I I I I I I I 601 I I I I I I I 1--+--+-+I I I I I I I I I I I I I I I 50 I I I I I -I-I I I 401--+--I I I I I I I I I I I I I I I ~I , I , I , I I I 30 I I I I I I I I I I I I L 20 I I I I I I I I I I I I :i; I I , I I I I ---+---+---+-----1 I I -~:~1 WATANA RESERVOIR ELEVATION (fT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY 2090 2100 21'0 2120 10 I I I I I I I ,-I I I ~~,~:,:,~~i~~t.~::::$;:~~:" §l:~~-;:~~W.~~~~I~:~:~~~*:~~:-b..~3:«!2r.?!:!l!:I~!:~!:~ 2130 2140 21S0 2160 2110 ------+~ 2180 2190 Tl o w w. .j:4 i 1 1 '"11 I J '-I c-'~l '11 I I I j ENVIRONMENTAL,FLOW REQUIREMENTS CAS E E:U: WATANAJOEVIL CANYON OPERATION-2002 DEMAND 5238GWH 50.000 ,iii iii Iii i ... .:.:.:.:::.""'. ) NOTE 1.DI.CHARQE FOR aU8ITNA "'VEA AT GOlD CReEK 2.PERCENT OF TIME .0,000 ;: : : ;::;PROJECT FLOW 18 6%EQUALLED ORnEXCEEDEDIN A GIVENnJLJL..-WEEK.CURVES ARE ~ .............,."".,BASED ON 34 YEARS............'...."...>OF AVERAGE WEEKLY ..,................«FLOWS. lJ(30,OOO ',,,,.,,,,.":'.,.'.'I',./"",.'•.•.,,""':...)•.••••3.MAINTENANCE OF 75"'~ ::;<I '.•.•'.,.'77·.<..»<1 •.•,,1/>CHINOOK SALMON<',:I 81DE CHANNEL REARING HABITAT YEARS 20,000 •..._... UJ CJ a: ~ 1: (J (J)-a -enu. (J '..-' 1 0,000 "'PI!"""""!!'~ "ll G) W W, ~o ~ JAN 'I!.MAN A""MAY JUN JUL AUG 8EP OCT NOV IlEC HARZA-EBASCO SUSITNA JOINT VENTURE ,ALASKA POWER AUTHORITY ~1II J ~l e---l -----w i I 1 1 ]1-_.)1•J J -I W I 0'\ -I:- ...... t- Z Woa:w 0.. '-' WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON OCTOBER 1 WATANA AND DEVIL .CANYON OPERATION 100.I I I I I I I I I I I I • •iii i 1 NOTE: BASED ON PROJECTED LLl J IUJ I 'L 901-ANNUAL ENERGY DEMAND --~--+---+-+-----+-----{~+_-l------Jl OF 5238 GWH IN THE YEAR 2002 80 I-,I I , , , ,I I I I ~I I I I I ~,I I I -, 101---+----+---+---I I I --+--+-+--+----f--+------f---+_I I I +----+---t--I I I- 60 1----4--1--+---+-+---+----I-----f---{------+-+--~-I__-_+__--l_____+__- >- !::: ...J iii-<~ If ~O 1---.....-..---f--+----+------l----+---+--{---+-----f---+---+-+.I -J----l--I I I I I +--I 40 I I I I I I I I I I I I I I I I I I +--I l---l JO I I I I I I I I I I I I I I I I I I j I I I I I 20 I---I I I I -+~----!-I +I I I I I I I I I I I I I I ~:i:i .--- 101 I I I I -t---t--t---t----t I I I I I I I I I I I I I --- 01 I I I I I 2060 2010 2080 2090 2100 2110 2120 2130 2140 2150 2160 2110 2180 2'90 WATANA RESERVOIR ELEVATION (FT) "'AA7A-FA4~~n ~1J~ITN4 JOINT VENTURE ALASKA POWER AUTHORITY TI C) w w ~ OJ -1 ~1I I -~.~~l , I 1 1 1 1 I 'j I I j ) WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JANUARY 1 WATANA AND DEVIL CANYON OPERATION 100 I iii •I I I I Ii'I I I Iii I - ----- 90~--··-·- NOTE: BASED ON PROJECTED ~--I---I--+--+--t-I I ·-+---!---+--II I I ~ANNUAL ENERGY DEMAND OF 5238 GWH IN THE YEAR 2002 80 I I I I 'I I I I --t----t--- W I 0"\ In .......... Zwo II: W 11...... 101----+-+,·_--+----+I I I ~ 60 l---t--.+-_.+---~-_.--f---~.---+_~-+--+_--+---t--t-----t----+·-I I ---+---+I I ---+---t I t >-t: ...J iii<~ f ~O I I I I I I I I I I I I I I I I I I I I 401 , I ---t-I I I I I I I -l--+I +--+--I I I -l-~-- 30 I I I I I I I I I +----t I I I I I I I I I 20 I I I t---t---+-+----+--+I I I I I I I I I I I 10 I I I I I I I +~-I I I -I I I I +---+----~-----t----t-- WATANA RESERVOIR ELEVATION (FT) UAD7A_I:RA~~n ~II~ITNA .lniNT VI:NTIJAI=ALASKA POWER AUTHORITY U I I I I I ---.--l__..I __Il--_.LI__..1__L-_-l-_....L_-L_--I==I--_L.._....L_...l 2060 2010 2080 2090 2100 2110 2120 2130 2140 2150 2160 :IJIII ;>110 2180 2190 "T1 C) w w. -., 1 -. j 1 -I I --, J I 'll l! -1 ~-"~-l 1 I 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON APRIL 1 WATANA AND DEVIL CANYON OPERATION 100,...-----------I I • I I I I I I I 1 I I I I I I -,--"-------- 90 I----t----t---+--t~+_____+-~t---t_-_+_--__t__-_t-t__I I ••I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 5238 GWH IN THE YEAR 2002 801--+--+1+--+--1 I -t---+---+1 t-t----i-1 1 I 1 I I I T I I I 60 1---g--t-'----+---4 ---+--+---t-+---t-+---·t----t --t--t---+--1 I L,) I 0'\ 0'\ ,.... t- Z Woa:w Q....... 10 J----~--+~-,1 , I 1--I----t I 1 I 1 1 1 1 1 +I I I 40 f-I I I I I I I I I 1 I I 1 I +---+----+---+------+--+--+---1----+_..-+I I 50 I I +----+_____-t_-t-I 1 I 1 1 I I 1-+---4--+---+----1--I I I I +I l--t>-t: -l iii <I( ~g: JO I I I I I I,--t---+----+--t , I I I I (( ;:;0:-: 20 I I I I I I I I I I I I I I '0 I I I I I I I I I I I I I I :§*L..:.J I I -·!----4--+---t--+---~--- ml~~~~ WATANA RESERVOIR ELEVATION (FT) AI A~1t'A DnUII:a AIiTunalTV :;~ 01 I I I 1 I 2060 2010 2080 2090 2100 2110 2120 ...................raft",.~••~.........1ft.11I....••~.......~~ 2140 2'50 2160 :'110 2'60 2190 0] Gl L) L) I OJ ~-" j -1 -'/I J 1 '--1 )I ))J ---1 , I J ]I WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JULY 1 WATANA AND DEVIL CANYON OPERATION 100 I I I I I I I I I I I I I I i I I I I 901---t--'l--I I -1---+---+I I -+----+---+--1 I I 1----4--~ NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 5238 GWH IN THE YEAR 2002 80 J--;I I . I I I I t--+--+--+---+II f I I I I I I I I I I I 10 i----+--.+-H-+--,+-t---t---+---+--+-.-+-----+I I I I I -+-+--+---I I I I I 1 I W I (J\ ....... ,.... !Zwoa:wa....... 601----1--+"-4 --4--+----I--+--·f--+--·n.+--.-+,--+---f-----f-I -1------1-I I.--+--+-+--+--t-- >- ~ :J iii<~a: 4. ~O I I I I --+--I I I I I I I I I I I I I I I If+-- ..0 I I J'-+---l----t---+-I I I -+--+---I I I I I I 1 I I I 1----, .~~~! ;}O I I I I I I I -+I I I I I I I I I I I I I I -t-n-~:;~:i:i:H-·---~----·1 20 I I I I +--+--+----+I I -+-I f ;~:;:;~:i:j:~I I ;:;:!~:;:;:;::: :~;~~:~;::: WA T ANA RESERVOIR ELEVATION (FT) U.4A7.4-FA.4SCO SII~ITN.4 .lniNT VENTUA~ALASKA POWER AUTHORITY 101 I I I I -+----+--!-~+___+_I I I I I I I I I I I o I I I I I I I I I 2060 2010 2080 2090 2100 2'10 2120 2'40 I 2110 2'80 2,90 "'Tl C) w w CD r FIG.3.3-20 WATANA RESERVOIR WATER LEVELS WATANA AND DEVIL CANYON OPERATING 2002 SIMULATION CASE E-VI OCT NOV DEC JAN FEB MAR APR MAY JUN .JUL AUG SEPT 2200 2190 1"'''2180 2170 .....2160 2150.... 2140 2130 ~'iiii! 2120 .... 2110 -2100 2090 ~2080 2070 2060 .... I I I I I Ir--NORMAL MAXIMUM POOL EL.2185 --L~i ~// ~;17 /Vf', ~"',//"...-..........~ "~~/J J ,",,/,',,-"'"'"....--....-/7"~, ""V i\,---i ''\/.. '\,/'", ',,- II1"- ''\7 1'/",,- NOTE:RESERVOIR LEVELS SHOWN ARE BASED ON MONTHLYr-AVERAGE VALUES AND ARE PLOTTED AT MID-MONTH I I I I I 3-68 MAXIMUM MEAN MINIMUM HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY FIG.3.3-21 .... DEVIL CANYON WATER LEVELS 2002 SIMULATION CASE E-VI MINIMUM MEAN /-MAX MUM ,....-~--/1 ~/I Vi '\ ................. '~---- NOTE:RESERVOIR LEVELS SHOWN ARE BASED ON MONTHLY AVERAGE VALUES AND ARE I PLOTTED 1T MIDiMONT7 1400 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT 1410 1450 1460 1430 1440 1420 r,,, r I i 3-69,..... HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY I ]1 '-'II 1 1 1 1 1 'llI 1 J ENVIRONMENTAL,FLOW REQUIREMENTS CASE E n WATANA/DEVIL CANYON OPERATION-2020 DEMAND 8312GWH SO,OOO ii'iii iii I i 40,000 I I I I I I I I I I .. 0 1'"""";;''':'''I'i;;;;:,,'~~ii;;;;i;I]~t LIrDICATE~MIN F~L~~';,i,i;!n:;i"~~ JAN '11 MAlt APR MAY JUN JUl AUG SEP oct NOV DEC HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY ....~ FIG.3.3-23 WATANA RESERVOIR WATER LEVELS WATANA AND DEVIL CANYON OPERATING 2020 SIMULATION CASE E-VI 2200 2190 .....2180 ~Wil 2170 ms~2160 2150 ",a 2140 2130 2120 2110 ~~ 2100 .....2090 ~1Bll,l!2080 2070 2060 I I 1 I I V-NORMAL MAXIMUM POOL EL.2185 ) '"--'-L--- "-,I~~ '\/\. ""-~\I V"\\,I /1\\\\1\//-- ~"\' / I //1\'\/ ""\II I \/ '\I ''\\\/I / " '\,\~.I V / "\..I "\\\~1///1\,/ '\"[7/'\~I\. "/7 "'"'"ro-1/-NOTE:RESERVOIR LEVELS SHOWN ~ ARE BASED ON MONTHLY AVERAGE VALUES AND ARE PLOTTED AT MID-MONTH I I I I I MAXIMUM MEAN MINIMUM OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT ~-3-71 HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY FIG.3.3-24 DEVIL CANYON WATER LEVELS 2020 SIMULATION CASE E-VI /MAXIIMUM V 10-----//-..,~......M~AN] v 1\.......~ \ , !I I \ J.I-MIN MUM \ I 1\ !MINIM~M:-~ I \ /\ /'\ i /NOTE:RESERVOIR LEVELS SHOWN,"",ARE BASED ON MONTHLY AVERAGE VALUES AND ARE PLOTTED AT MID-MONTH II I 'I I1400 OCT NOV DEC JAN FEB MAR APR MAY JUN'JUL AUG SEPT 1430 1410 1420 1440 1460 1450 ..... !,.... 3-72 '.IARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY 1 ]"--J I 1 j 1 ))1 11 1 .1 W I ....... W .30000 -~20000 u-- :zo -'lL 5o ..J ([ 5100QO I- WATANR ~DEVIL CANYON DOUBLE RESERVOIR OPERRTION E-VI.LOAD YR.2020 WATANA ...lIOIIB h ~- - L I l l II ~'I , I II ~ U r if r ,.~'"V "• HARZA-EBASCO SUSITNA JOINT 'VENTURE ALASKA POWER AUTHORITY o •1950 .1955 1960 1965 1970 1975 1980 1985 "P ~w I N VI ~-.J '.I ---''l! I -11 II '11 J ~1 ------1 ..,-1 1 ),11 B 30000 ,... (f) l.Lu20000 ~ w 3:~0 .po .....J lL Z-n::..-o>ffi 10000 (J) ~ WRTANR ~DEVIL C~NYON DOUBLE RESERVOIR OPERATION [-VI.LOAD YR.2020 DEVIL CANYON tIAX 9654. -, , ...P\l\1 ~~Il L n~~,~~~l I'it L ~l ~~ ~~f ~~l " II ~,• ·r o I 1950 1955 1960 1965 1970 1975 1980 1985 :::!:! P HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY w (,.) t Nm 1 I -j! j 1 ---J 1 1 -11 J 1 1 •1 I M 11 ]I W I...... \Jl • 30000 -' ~20000u- :t .0'.J lL. ~o -J ([ 610000 t- WRTANR ~DEVIL CANYON ,DOUBLE RESERVOIR OPERRTION E-VI.LOAD YR.2020 DEVIL CANYON IIfI(9554. I b I ~t l I\... ~~~M I ~,IIIIiIIILAirlJIrrI~r \I" • o •1950 1955 1960 1965 1970 1975 1980 1985 OJ P HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY Col Col, N -..l 1 ).-··¥---ll J -1 '"I J ]1 1 1 ) I J 1•,J )1 2200 -t- u-2150- za..... VJ ~ I a:-...J >0'W -J w2100 wu <I lL fr: :J U) 15 2050~a: :I WATANR &DEVIL CANYON DOUBLE RESERVOIR OPERATION E-VI.LOAD YR.2020 WATANA \" 2000 . 1950 1955 1960 1965 1970 1975 1980 1985 'T\ Q HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY ~ CN I I\) (Xl 1 --"J I ") J J )J J )'I 1 .'1 W I ....... ....... 1550 t- ~1500 zo..... t-a:>w -I Wt450 wu ([ lLtr :J U> ~1400 ([ :l: WRTANR &DEVIL CRNYON DOUBLE RESERVOIR OPER~TION E-VI.LOAD YR.2020 DEVIL CANYON - ..,...........r----,•I .". I •.,'I I I ••\I I •,I , 1350 •1950 1955 1960 1965 1970 1975 1980 1985 -np HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY '"'". l\) CD 1 1 ---Ii I i 1 ·_·1 J \\l.II )Ij J ]J -1 )I 1 j WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON OCTOBER 1 WATANA AND DEVIL CANYON OPERATION 100 I I I I f I i I I I i I I 1 I • I • •-------------, 90 ~+-·l-----+--+-~---+--t--l---+---+- NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 8312 GWH IN THE YEAR 2020 80 I-I I I - I I I -t--I I -+--+--t I I I --I I 1 I I I I I • I 40 I I I I I I I I I I I I I I I 1 I I I I I I----+-~~--- -----I-------f--+---+_I I I 1 I +----t--+--~t____+__1 1 I '01 I I I I I ..I I ,.-I I I I I :~~-~::::::~::I I I I :;f~z,;,~;,;, I I I I I I I ~- 10 I--+~I----+---I I -+I +---~ 601---+---+---+--+_·+-~+--+---t-+----+---t--+--+--+---1--I -t 1 I 1 I I I I 1--1 >- '=-Jm-<~a: 4. ,...... ~ Z Woa:w Q....... W I -...J 00 30 1 I I I I I --+-I I I 1 1 I I 1 I I I 1 1 1--+-;i~;§;::; 20 I I I I I 1 I I I I 1 I 1 I I I 1 I I I I I I I -- 10 t--+I I I I I I I I I I I I I I 11"--1 L=::J I I I OL....--'_--.-L_-L_---'---_L-------.-JL.----'_--.-L_---L_...L_.L..--.-JI.---...i_--.-L_...ti:i:;;;;;;;:;L....-L---'----l:;;;:;:;:l~=:iI:i:il=@:i:~I:i:l:i:l~::z,:,:,"'"---.....J 2060 2010 2080 2090 2100 2110 2120 2130 21!)0 2160 2180 2190 WATANA RESERVOIR ELEVATION (FT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY "TI Q w W, w o .I i 1 1 1 ~1 I C-~~-J 1 -)I I I 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JANUARY 1 WATANA AND DEVIL CANYON OPERATION WATANA RESERVOIR ELEVATION (FT) HARZA-EBASCO SUSITNA JOINT VENTURE ALASKA POWER AUTHORITY -n Cl (,,) (,,) (,,) ._.~--- NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 8312 GWH IN THE YEAR 2020 I I :,,:;~'.."·1"I~:..... '~,§ <'~~:.:::*:*=~ ...~. .;,.::..:..:;:..~ ,.,;~'.:,~.:':oJ~',.:.::..''~..• '" , ~'..0...00-i:=:l '"~:::::i~~:,:'°0 "••~:.~ 40 20 o 2060 2010 2080 2090 2100 2110 2120 2130 2140 2150 2160 2170 2180 2190 10 30 80 5u 90 60 10 100 >-.... ~ iii 4( ~ II: 0.. ...-......zw ~w ~ '--' W I -..,J "" 1 1 -]I -1 ..~-)~--l ]J 1 J 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON APRIL 1 WATANA AND DEVIL CANYON OPERATION 100 I r r I I I I I I I I I I , I I I I I -~--- 90 I---+--_.-~...1 I +--1---1 I I 1 I ~--I I I I I I NOTE: BASED ON PROJECTED ANNUAL ENERGY DEMAND OF 8312 GWH IN THE YEAR 2020 80 I I ':.---+.I I 1 I I 1 +---1 I I I I I I I I • •• • •• 60 1 1 I I I 1 I 1 I I I I I I 1-1-1 -+I I I I I +-I 1·--1 W I 00o ,..... t- Z W ~wa.. '-J 701----+-+--+-_.-+I I -+--+---1-----+---+1 I I I I ----l--+__+I I I 1 I -I -~I I I I I~Ur I I I •I ~!!!!!! I I I I I I I +I I +--+--4-------+----+-----+-...I I I >-t: -J iii 4( ~ ~ t~:;~;:~:: 40 I I I I I I I ! !-+-! ! ! ! !+~--+-.- 30 I I 1 I I I ·+--1 I +-+-+-·--l----+---+------l·--+--+---~---- 20 I I I I I I 10 I I I I I I --+-----I----~--_.j--- I I I I I -.j.....--+------+--+--+---+--t----.~- .-.,~._- ._- WATANA RESERVOIR ELEVATION (FT) N4R74-I=R4!Ctr-n AII!CtITN4 .lniNT VENTURE ALASKA POWER AUTHORITY • I ~ u I 1 1 il~~~~~I~i~;§;~~J 2060 2070 2080 2090 ~~~~~tiEi~; 2100 2110 2120 2130 2140 2150 2160 2170 2180 2190 Ti D w w W N ]1 I J I J 1 "1--1 1 WATANA RESERVOIR SURFACE ELEVATION PROBABILITY OF OCCURRENCE ON JULY 1 WATANA AND DEVIL CANYON OPERATION 100 I r I I I I I I I I I I I I I I I 1 • _._--~~ 90 I---+.-u+.---f-----t.~-+-~_+.~t--+·--t--+--+----+--·I I I NOTE: BASED ON PROJECTED -----t-~t ANNUAL ENERGY DEMAND OF 8312 GWH IN THE YEAR 2020 80 t----+-I I .I I I --+---+-+--+----+---+-I I I I I I I I I T I • I .~ 10 I---'~---., , , I _+---I----+----+~, , , , ,I +--t-I +--+--I , I W I 00 t-' '""""~zw () a::w Q.. '-' 60 I I +--.+.--+---+-----+----+--+---t---4--+--/--f---I I I ~I I I I I I I 40 I I I I I I I I I I I I I I I +---1--1-1 I I --+-----+--+--t I I >-c ~ m-<~ ~ ~o i-----......----....-.--~.+-..~._.;-"-.-+-----+-----------_.~-~~I ,-+---+--+!I I +I l---j 30 I I I I I I I I I I I I , I I I ---......._..,---_a_-----_••--_+_--_..-.--+---~-J---~___l_--- 20 I-I I I I I I I I I I ;:~~:; I I I I .--+---+---f---.-.-...~ 10 I I I , I I I I I ,I j~~$;1~:~*:§I:.............i----+---+-----+--~...-~--~.-..~....~ WATANA RESERVOIR ELEVATION (fT) N4R74-I=R.4~r.n AlJAITN4 .lniNT VI=NTUR~ALASKA POWER AUTHORITY I::::-n C) w w. w w 21902180211021602150214021302120 ~~~;~~~l .. 2 I 10209020602010 01 I I I2060 I I I I ":',. ""'" ..... ..... - -, 4.°FLOW REQUIREMENTS DURING DAM CONSTRUCTION AND RESERVOIR IMPOUNDMENT 4.1 WATANA DAM During construction of the Watana Dam,pr10r to impoundment of the reservoir,the r1ver flows will be unaffe:cted and impacts will be as described in the License Appl ication (p.E-2·-65 to E-2-77). When impoundment of the Watana Reservoir begins,the flow requirements will be the same as Case E-VI for the period of May through October (water weeks 31 through 5).From November through April,the policy will be to release the inflow and hold the reservoir level const.ant.The rationale for this 1S explained in the License Application (p.E-2-78).In dry years,defined in the same manner as for project operat ion,the minimum flow requirements at Gold Creek would be reduced by 1,000 cfs from the flow requirements in other years.This reduction would apply from May through October only. An additional constraint during filling is the requirement to provide freeboard 1n the reserV01r to contain the 250-year flood (License Application p.E-2-79).This prevents the imposition of maximum flow requirements at Gold Creek during filling.Such requirements would limit the ability to discharge floods and cause water levels to infringe on freeboard requirements.The filling flow rE~quirements are given on Table 4.1-1. The filling of Watana Reservoir has been simulated in a manner similar to tha t given In the License Application (p.E;-2-79).We t,dry and average three-year streamflow sequences given in the License Application (p.E-2-80 and Table E.2.37)were routed through the re~lervoir.The same construction sequence,including dam elevations,was used.The sequences of pre-filling streamflows at the Watana Dam Site and at Gold Creek are shown on Table 4.2-2.The sequences of flows at Watantl and Gold Creek during filling are shown on Tables 4.1-3 and 4.1-4 respectively.Figure 4.1-1 shows the 421543 850226 4-1 ..... ..... I ..... progression of the dam crest elevation during construction t the impounded water surface elevation t and the sequences of flows at Gold Creek • The simulation of filling t using the 90%exc~!edance flow sequence t was used to develop target reservoir elevat ions wh ic:h could be used to determine whether flow requirements at Gold Creek should be reduced by ltOOO cfs for the next month.These target elevations represent the water levels attained at the ends of the months with the dry flow sequence.The Watana reservoir volume and surface area plot in the License Application (Fig.E.2.l28)was used in the routing.Target elevations are shown on Table 4.1-1. The computations indicate that the Watana Reservoir could be filled to its normal maximum water level (El.2185)for wet and average sequences in about the same time using either Case C or Case E-VI.By August of the third summer of filling t the reservoir would be full.In a dry sequence t however, the reservoir water level would reach El.2175 at the end of the third summer of filling.This is 10 feet abOVE!a dry sequence filling with Case C• 421543 850226 4-2 Table 4.1-1 SUSITNA HYDROELECTRIC l?ROJECT E-VI FLOW REQUIREMENTS DURING FILLING OF WATANA RES]~RVOIR - ..... - Watana Target Minimum Flow Requirements Res.Elev.l/at Gold Creek.£/ Water Second Third If WSELJlMeets or If WSEL Is Week Date Summer Summer E;ltceeds Target Below Target 1 Oct I-Oct 7 6,000 5,000 2 Oct 8-0ct 14 6,000 5,000 3 Oct l5-0ct 21 5,000 4,000 4 Oct 22-0ct 28 4,000 3,000 5 Oct 29-Nov 4 2,055 3,000 2,000 6 Nov 5 Natural Natural through 30 Apr 28 Natural Natural 31 Apr 29-May 5 2,055 2,000 2,000 32 May 6-May 12 4,000 3,000 33 May l3-May 19 6,000 5,000 34 May 20-May 26 6,000 5,000 35 May 27-June 2 1,908 2,074 6,000 5,000 36 June-3-June 9 9,000 8,000 37 June 10-June 16 9,000 8,000 38 June l7-June 23 9,000 8,000 39 June 24-June 30 1,965 2,110 9,000 8,000 40 July I-July 7 9,000 8,000 41 July 8-July 14 9,000 8,000 42 July IS-July 21 9,000 8,000 43 July 22-July 28 9,000 8,000 44 July 29-Aug 4 2,006 2,140 9,000 8,000 45 Aug 5-Aug 11 9,000 8,000 46 Aug 12-Aug 18 9,000 8,000 47 Aug 19-Aug 25 9,000 8,000 48 Aug 26-Sept 1 2,037 2,162 9,000 8,000 49 Sept 2-Sept 8 8,000 7,000 50 Sept 9-Sept 15 7,000 6,000 51 Sept l6-Sept 22 6,000 5,000 52 Sept 23-Sept 30 2,052 2,173 6,000 5,000 l/surface elevations measured on last day of month lending ln given water week 2JThere are no maximum flow constraints during filling r-l/wsEL =water surface elevationI 421543 850226 4-3 Table 4.1-2 SUSITNA HYDROELECTRIC PROJECT PRE-PROJECT STREAMFLOW SEQUENCES USED IN FILLING S IHULATIONl/ Dry Average Wet Month 90%Exceedence 50%Exceedence 10%Exceedence Watana Gold Creek Watana Gold Creek Watana Gold Creek October 4,213 5,073 4,713 5,732 5,272 6,453 November 1,879 2,263 2,102 2,557 2,352 2,879 December 1,312 1,580 1,468 1,785 1,642 2,010 January 1,071 1,290 1,198 1,457 1,340 1,640 February 910 1,096 1,018 1,238 1,138 1,393 March 822 990 919 1,118 1,028 1,258 April 1,008 1,214 1,127 1,371 1,261 1,544 May 9,715 11,699 10,870 13,221 12,158 14,882 June 20,238 24,371 22,644 27,541 25,326 31,001 July 17,842 21,486 19,963 24,280 22,327 27,330 August 16,095 19,382 18,008 21,903 20,142 24,655 September 9,641 11,610 10,787 13,120 12,064 14,767 l/See Table E.2.37 of License Application 421543 850226 4-4 Table 4.1-3 SUSITNA HYDROELECTRIC PROJECT SUSITNA RIVER DISCHARGES (efs) MEASURED AT WATANA DURING WATANA FILLING CASE E-VI FLOW REQUIREMENTS Wet Seq uence Avg Sequence Dry Sequence Water Year 10%Exceedence 50%Exceedence 90%Exceedence 1991 Apr 1,261 1,127 1,008 May 8,690 7,402 6,247 June 20,005 17,323 14,917 July 5,309 4,683 5,356 Aug 14,993 11,121 6,414 Sept 6,743 5,466 4,831 1992 Oct 5,272 4,713 4,172 Nov 2,352 2,102 1,879 Dec 1,642 1,468 1,312 Jan 1,340 1,198 1,071 Feb 1,138 1,018 910 Mar 1,028 919 812 Apr 1,261 1,127 1,008 May 2,179 2,552 2,919 June 3,125 3,903 3,667 July 7,797 4,683 14,356 Aug 8,649 5,105 4,713 Sept 4,097 4,467 3,831 1993 Oct 3,851 4,013 3,172 Nov 2,352 2,102 1,879 Dec 1,642 1,468 1,312 Jan 1,340 1,198 1,071 Feb 1,138 1,018 910 Mar 1,028 919 822 Apr 1,261 1,127 1,008 May 2,179 2,552 1,919 June 8,958 3,903 3,667 July 3,997 4,683 4,356 Aug 12,862 5,105 4,713 Sept 8,766 3,831 Oct 3,172 421543 850226 4-5 - - -- Table 4.1-4 SUSITNA HYDROELECTRIC PROJECT SUSITNA RIVER DISCHARGES (efa) MEASURED AT GOLD C.REEK DURING WATANA FILLTNG CASE E-VI FLOW REQUIREMENTS , Wet Sequence Avg.Sequence Dry Sequence Year Month 10%Exceedance 50%Exceedance 90%Exceedance 1991 April 1,544 1,371 1,214 May 11 ,414 9,753 8,231 June 25,680 22,220 19,050 July 10,312 9,000 9,000 August 19,506 15,016 9,701 Sept 9,446 7,7'99 6,800 1992 Oct 6,453 5,732 5,032 Nov 2,879 2,557 2,263 Dec 2,010 1,785 1,580 Jan 1,640 1,457 1,290 Feb 1,393 1,238 1,096 Mar 1,258 1,118 990 Apr 1,544 1,371 1,214 May 4,903 4,903 4,903 June 8,800 8,800 7,800 July 12,800 9,000 8,000 Aug 13,162 9,000 8,000 Sept 6,800 6,800 5,800 1993 Oct 5,032 5,032 4,032 Nov 2,879 2,557 2,263 Dec 2,010 1,785 1,580 Jan 1,640 1,457 1,290 Feb 1,393 1,238 1,096 Mar 1,258 1,118 990 Apr 1,544 1,371 1,214 May 4,903 4,903 3,903 June 14,633 8,800 7,800 July 9,000 9,000 8,000 Aug 17,375 9,000 8,000 Sept 11 ,099 5,800 421543 850226 4-6 - 4.2 DEVIL CANYON DAM During the construction of Devil Canyon Dam,before the impounding of any water in the reservoir,the Case E-VI flow requirements at Gold Creek will be maintained.No significant change in water quality parameters is expected as a result of using Case E-VI rather than Case C during Devil Canyon construction. Devil Canyon Reservoir would be filled 1n the same two-phase manner as described in the License Application (pp.E··Z-148 to E-Z-150).During the .....first phase of fill ing,the water level will be raised from near El.850 to El.1135.This will require impounding approximately 76,000 acre feet of water.The Case E-VI operational flow requirements will be maintained during this period.The second phase of filling will require impounding about 1,000,000 acre feet of water and will raise the water level to its normal operating level,El.1455.Case E-VI operational flow requirements will be maintained during this period. Case E-VI flow requirements are generally lo'wer than Case C for the period August through May and higher for June and July.Therefore,the time required to fill Devil Canyon for each phase would depend on the time of year,but would not be significantly differE!Ot than stated 1n the License Application.The discuss ion of water quality impacts,presented in the .... ,.... I License Application,remains valid • 421543 850226 4-7 J ..__.-1 1 ]--]_.-]]c-~1 ]]1 1 ]I 1 1 J J F M A M J J A SON D J F M A M J J A SON.D J F M A M J J A SON D J F M A M J J A SON 0 .-~:--.....-_,,:- 1--~l--~l.--- "'~ ?p ---1-,..--r--.;.-,.......",'V _.-I--I---I-- ~...... /'IA ..... >---f-I--WATANA DAM CREST EL.1--.-V ~~ '\V V\....f1"......- ~~"J"'..... V r----I-V iI....R,ESIERIV~IRI WfTfR J LrV'fL /10%EXCEEOANCE ----50%EXCEEDANCE ----90%EXCEEOANCEIII I I I I I I I I I 2200 1"'"\2100 U) E 2000.--'-'1900 Z 0 1800t= c( 1700>W -J W 1600 1500 1400 1990 1991 1992 1993 40000 35000 30000,....... UJ-0 25000'-' W C)20000 ex:-<::z::15000 0 ~100000 5000 0 I I I I I I I I I I I I I I SUSITNA RIVER FLOWS AT GOLD CREEK - ,,1\FILLING OF WAT ANA RESERVOIR - If''\~CASE E-VI FlOW REQUIREMENTS I 1', '\f\1\-I}1/ ,,~ A r"\:1'~ \\~I \.r f\/\\\,...- ~W ~,...,~~-R ,e ...£-~ '\.....~.~t 'I ~~r-... 1 ~j ~v .....,~~ "-t:::::-.I "'--j--J F.M A M J J A SON D J F M A M J J A SON 0 J F M A M J J A SON D J F M A M J J A SON 0 "C5 C :IJ rn ~.... I.... HARZA-EBASCO SUSJTNA JOINT VENTURE ALASKA POWER AUTHORITY - _r-" I REFERENCES """ - r 5.0 REFERENCES - - REFERENCES Acres American t Inc.1982.Susitna Hydroelectric Project t Feasibi lity Report,Volume 1 -Engineering and Economic Aspects,Section 12 of Final draft.Prepared for the Alaska PO'ler Authorit¥. Alaska Department of Fish and Game.1983.Winter Aquatic Studies (October 1982 -May 1983). Alaska De partmen t of Fi sh and Game.1984a.Adul t Anad romous Fi sh Investigations (May-October 1983).Susitna Hydro Aquatic Studies Report No.1. Alaska Department of Fish and Game.1984b.Resident and Juvenile Anadromous Fish Investigations (May-October 1983).Susitna Hydro Aquatic Studies Report No.2. Arctic Environmental Information and Data Center.1984a.Susitna Hydroelectric Project Aquatic Impact Assessment:Effects of Project- Related Changes in Temperature t TurbiditYt and Stream Discharge on Upper Susitna Salmon Resources During June through September.Prepared for the Alaska Power Authority. Arctic Environmental Information and Data Center.1984b.Assessment of the Effect of the Proposed Susitna Hydroelectric Project on Instream Temperature and Fishery Resources in the Watana to Talkeetna Reach. Final Report (2 Volumes)prepared for the Alaska Power Authority. Alaska Power Authority.1983a.FERC License Application Project No.7114- 000.Susitna Hydroelectric Project.Volun1e 1,Exhibit A. Alaska Power Authority.1983b.FERC License Application Project No.7114- 000.Susitna Hydroelectric Project.Volunle 2,Exhibit B. 422612 850204 5-1 ,-. r - Alaska Power Authority.1983c.FERC License Application Project No.7114- 000.Susitna Hydroelectric Project.Volume SA,Exhibit E,Chapters 1 and 2,195 pp. Alaska Power Authority.1983d.FERC License Application Project No.7114- 000.Susitna Hydroelectric Project.Volume 6A,Exhibit E,Chapter 3, 190 pp. Alaska Power Authority.1984a.Alaska POWi~r Authority Comments on the Federal Energy Regulatory Commission Draft Environmental Impact Statement of May 1984;Volume 6,Appendix IV -Temperature Simulations, Watana and Devil Canyon Reservoirs. Alaska Power Authority.1984b.Alaska Power Authority Comments on the Federal Energy Regulatory Commission Draft Envi ronmental Impact Statement of May 1984;Volume 7,Appendix V -Temperature Simulations, Susitna River Watana Dam to Sunshine Gaging Station,Open Water. Alaska Power Authority.1984c.Alaska Power Authority Comments on the Federal Energy Regulatory Commission Draft Environmental Impact Statement of May 1984;Volume 8,Appendix VI -River Ice Simulations, Susitna River,Watana Dam to Confluence of Susitna and Chulitna Rivers. Harza-Ebasco Susitna Joint Venture.1984a.Eklutna Lake Temperature and Ice Study (With Six Months Simulation for W~!itana Reservoir).Prepared for the Alaska Power Authority. Harza-Ebasco Susitna Joint Venture.1984b.Susitna Hydroelectric Project - Instream Ice Simulation Study.Prepared for the Alaska Power Authority. Harza-Ebasco Susitna Joint Venture.1984c.WE!ekly Flow Duration Curves and Observed and Filled Weekly Flows for the Susitna River Basin.Final Report prepared for the Alaska Power Authority. 422612 850204 S-2 - r - r- I I, r .- F"" I. I Harza-Ebasco Susitna Joint Venture.1984d.]~valuation of Alternative Flow Requirements.Final Report prepared for the Alaska Power Authority,55 pp. McPhail,J.D.,and C.C.Lindsey.1970.Freshwater Fishes of Northwestern Canada and Alaska.Fisheries Research Board of Canada,Bull.173. Scott,W.B.and E.J.Crossman.1973.Freshwater Fishes of Canada.Fisheries Research Board of Canada,Bull.184. Trihey,E.W.&A.1984.Response of Aquatic Habitat Surface Areas to Mainstem Discharge in the Talkeetna to Devil Canyon Reach of the Susitna River, Alaska.Final Report prepared for the Al~Lska Power Authority. Woodward-clyde Consultants.1984.Interim Mitigation Plan for Chum Spawning Habitat in Side Sloughs of the Middle Susitna River.Prepared for the Alaska Power Authority • 422612 850204 5-3