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HomeMy WebLinkAboutAPA2922dSUSITNA HYDROELECTRIC PROJECT AQUATIC MITIGATION REPORT SERIES IMPOUNDMENT AREA FISH MITIGATION PLAN Draft Mitigation Report No. 2 May 1985 Prepared By: Woodward-Clyde Consultants 701 Sesame Street Anchorage, Alaska 99503 In Association With: Entrix, I!"C. 4794 Business Park Boulevard Anchorage. Alaska 99503 Submitted To: Harza-Ebasco Susitna Joint Venture 711 H Street Anchorage, Alaska 99501 For : The Alaska Power Auhtority 327 W. 5th Avenue, 2nd Floor Anchorage, Alaska 99501 Preface This report represents one volume of a three volume report series on aquat ic mitigation planning for the proposed Susitna Hydroelectric Project. These volumes are: 1. Access, Construction and Transmission Aquati c Mitigation P l an 2. Impoundment Area Fish Mitigation Plan 3. Middle River Fish Mitigation Plan A primary goal of the Alaska Power Authority's mitigation policy is to maintain the productivity of natural reproducing popul ations, where possible. The planning process follows procedures set forth in the Alaska Power Authority Mitigation Policy for the Susitna Hydroelectric Project (APA 1982), which is based on the U .S. Fish and Wildlife Service and Alaska Department of Fish and Game mitigation policies. Mitigation planning is a continuing process, which evolves with advances in the design of the project, increased understanding of fish populations and habi tats in the basin and analysis of potential impacts. An important element of this evolution is frequen t consultation with the public and regulatory agencies to evaluate the adequacy of the planning process. Aquatic mitigation planning began during preparation of the Susitna Hydroelectric Project Feasibility Report (1981) and was further developed in the FERC License Application ( 1983). A detailed presentation of potential miti gation measures to mitigate impacts to chum salmon that spawn in side sloughs was prepared in November 1984. It is expected that the three reports in the present report series will also continue to evolve as the understanding of project effects is refined. iii PREFACE • LIST OF FIGURES • LIST OF TAmES . 1.0 2.0 3.0 INIRXlJC'I'ICI{ • 1.1 ~ to Mitigatiat. 1.2 Soope • PRlJECl' IESaUPI'ICJ{ AND OPERATIC!{. 2 .1 stage 1 watana Reservoir. 2. 2 stage 2 Devil Cmya1 Resetvoir. 2.3 stage 3 watana Reservoir. FISH RESaJRCES IN 'IHE IMFU.JN!MENl' ZCNES. 3.1 Arctic Gray1irg • 3.2 a.u:Dot. 3.3 Dolly Varden. 3.4 I.c.n:;oose SUcker • 3.5 Ralni Whitefish • 3.6 Sm¢ack Whitefish. 3.7 lake Trout. 3.8 Slimy Sculpin • 3.9 Chinook SalJoon. 4. 0 ANI'ICIPATED IMPACTS. 4 .1 stage 1 -watana Reservoir. 4.1.1 Inundation • 4.1.2 Drawdown • 4.1.3 water Quality. 4.1.4 Effects on Fish. iv ~ iii vi vii 1 1 4 6 6 7 7 9 9 13 13 15 15 16 16 16 17 18 18 18 18 20 24 TABIE OF am'ENlS (a::.ntinued) Page 4.2 stage 2 -Devil Qmyal Reservoir. 31 4.2.1 Immdatiat • 31 4.2.2 Drc1'WCown • 31 4.2.3 water Quality. 33 4.2.4 Effects cn Fish. 36 4.3 stage 3 -watana Resezvoir. 39 4.3.1 Immdaticn • 39 4.3.2 D:rawl::1awn • 42 4.3.3 water Quality. 42 4.3.4 Effects cn Fish. 42 5.0 SEUX:T!Cif OF EVAIIlATICif SPEX!LES. 47 6.0 IEVELOFMENI' OF MITIGATICif PIAN • 49 6.1 History ot ~ Mitigaticn P1annin;J. 49 6.2 Acquisiticn ot P.lblic Aooess. 50 6.2.1 Bac:kgro.ni • 50 6.2.2 Site Selecticn • 54 6.2.3 Costs. 54 6.2.4 Malit:orirq Sb.¥iies • 55 6.3 Habitat Ilrprovements. 55 6.3.1 Bac:kgro.ni • 55 6.3.2 Site Selection • 55 6.3.3 COsts. 57 6.3.4 Mcnitorirg Sb.¥iies • 57 6.4 Hatchery Prcpaqatiat ot Arctic Graylin; • 60 6.4.1 Bacl<gro.lrd • 60 6.4.2 Hatchery Ptop:gaticn Technology. 60 6.4.3 stoc::kin;J Ptogx:am Site Selection. 61 6.4.4 Costs. 62 6.4.5 Mcnitorin; Sb.¥iies • 62 7.0 LI'I'ERMURE CITED • 63 v LIST OF FIGURES Figure 1. Mitigation plan develcpnent and in'plementation. Figure 2. <.¢,ial Allalysis . • • • • • • • • • • • 3 Figure 3. stage 1 -Watana reservoir water levels 21 Figure 4. stage 2 -Devil cartyal water levels. 2020 si:nDJl.ation ca,se E-VI. • • • • • • • • • • • • • • • • • 34 Figure 5. stage 3 -Watana reservoir water levels. Watana and Devil cartyal q:eratirq. 2020 si:nDJl.ation case E-VI. • • 43 vi Table l. LIST OF TABlES Ccmta'l ani scientific names of fish species observed in the Watana ani Devil canyon ~t zones • • Table 2. Arctic qrayli.n; population estimates in selected • 10 tril::utaries of the watana ~ zones. • • • • • • • • • • 11 Table 3. Arctic qrayli.n; populatioo estimates in selected tril:utarles ot the Devil cartyal ~ zone • • • • • • • • 12 Table 4. Bl..lrbot total catch ani catch rates in the watana ~ zone • • • • • • • • • • • • • . • • Table 5. 'l'opograplical features ot selected tril::utaries within Table 6. S\mmal:y ot selected species~, sport value ani sensitivity to habitat alteratioo in trib.Ital:y habitats • • • • • 14 • • • • 19 of the ptq;osed stage 1 watana ~ zone. • • • • • . • • 27 Table 7. SUrmnal:y ot selected species al::lurmnce, sport value an:l sensitivity to habitat alteratiCX'l in mainstem habitats of the pl:'q)OSE!d stage 1 watana .iJrp::lumment zone. • • • . . • • • 30 Table 8. 'l'op:)grattllcal features of selected trirutaries within the pl:'q)OSE!d Devil canyon .iJrp::lumment. • • • • • • • • • • • • • 3 2 Table 9. SUrmnal:y of selected species al::lurmnce, sport value ani sensitivity to habitat alteratioo in trib.Ital:y habitats of the proposed Devil canyon~ zone. • • • • • . • . . 38 Table 10. 5ummary of of selected species al::lurmnce, sport value ani sensitivity to habitat alteration in mainstem habitats of the proposed Devil ca.rtya1 .iJrp::lumment zone. . . . . • • • • . 40 vii LISr OF TABUS (continued) Table 11. 'l'cpogl:a,l;ilical features of selected tr:ibrt:aries within the proposed stage 3 watana impa.1njment. • • • • • • • Table 12. SUimnary of selected species ab.Irx!ance, sport value and sensitivity to habitat alteratiat in lake habitats of the . 41 proposed stage 3 watana impa.1njment zone • • • • • • 46 Table 13. 'lqercy mwents Cl'l Illpoundment Mitiqatiat Plannin;J • . • • • • . 51 Table 14. rani acquisitiCI'lS and facilities dsvelqment projects currently p:tcposed by the state ot Alaska for the SUsitna River Bc!sin. • • • • • • • • • • • • • • • • • • • • • • • • 53 Table 15. Costs associated with rip-rap pluoement alorq both banks of a 1, 000' laq excavated slough or side channel in the middle SUsitna River. • • • • • • • • • • • • • • • • • • • • • • • . • 58 Table 16. Annual m::arl.torin;J costs for evaluatin;J habitat inprovements in the middle SUsi tna River. • • • • • • • • • • • . • • • • • • 59 viii 1.0 INTRODUCTION 1.1 APPROACH TO MITIGATION The Alaska Power Authority's (APA) goal for the Susitna Hydroelectric Project fisheries mitigation is to maintain the productivity of natural reproducing populations (APA 1982). This is consistent with the mitigation goals of the U.S. Fis h and Wildlife Service (USFWS) and the Alaska Department of Fish and Game (ADF&G) (APA 1982, ADF&G 1982a, USFWS 1981). When possible, maintaining existing habitat quantity and quality is preferred. Where this is infeasible, replacement habitat will be provided in sufficient quantity and quality to support this productivity. If it is not possible to achieve this goal, APA will provide compensation for the impact with means agreed upon by the agencies. The development and implementation of the fish mitigation plan follows a logical step-by-step process. This process and its major components are illustrated in Figure l. The options proposed to mitigate for impacts of the Susitna Hydroelectric Project are analyzed according to the hierarchical scheme shown in Figure 2. Mitigation options can be grouped into two broad categories based on different approaches: (l) Modifications to design, construction, or operation of the project; or (2) Resource management strategies. The first approach is project specific and emphasizes measures that avoid or minimize adverse impacts according to the USFWS Mitigation Policy adopted by the APA (1982) and coordinating agencies (ADF&G 1982a, USFWS 1981 ). These measures involve adjusting or adding project features during design and planning so that mitigation becomes a built-in component of project actions. Figure 1 IDENTIFICATION OF IMPACTS AND GOALS OF PLAN OPTION ANALYSIS l NEGOTIATION OF ACCEPTABLE PLAN IMPLEMENTATION OF PLAN ... MONITORING OF PLAN PLAN MODIFICATION COMPLETION OF MITIGATION TERMINATION OF MONITORING Mitigation plan development and implementi11tion 2 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT Woodw•rd·Ciyde Consulhlnta AND ENTRIX, INC. HARZA ·EBASCO SUSITNA JOINT VENTURE PARTIAL AVOIDA.•CE ~'----A_v_o_Ir-D-AN_c_E __ __,jt----+) TOTAL AVO IDA.NC E I PARTIAL RECTIFICATION I PARTIAL COMPENSATION ~ NO AVOIDANCE 1 MINIMIZATION I NO MlNIMIZATION 1 RECTIFICATION NO RECT~FICATION l REDUCTION I NO REDUCTION l COMPENSATION I NO COMPENSATION UNMITIGATED/LOSS RESIDUAL IMPACT 1---~ SOME MINIMIZATION ~--.. TOTAL RECTIFICATION 1-----.. SOME REDUCTION t----.TOTAl COMPENSATION Figure 2 Option Analysis 3 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT Woodward-Clyde Consultants AND ENTRIX, INC. HAAZA·EBASCO SUSITNA JOINT VENTURE When impacts cannot be avoided or minimized by the first approach , measures that rectify, reduce or compensate will be implemented. These types of mitigation measures will require concurrence of resource management hoards or agencies with jurisdiction over resources within the project area. Mitigation planning for the Susitna Hydroelectric Project has emphasized both approaches. The sequence of option analysis from avoidance through compensation has been applied to each anticipated impact. If full mitigation can be achieved at a high priority option, lower options may not be considered. Monitoring of mitigation features is recognized as an integral part of the mitigation process. And, in some cases, maintenance may be a necessary part of the mitigation plan. A general approach to monitoring has been developed by the APA and will be applied to the fishery resources and their habitats. As fish mitigation plans are agreed upon by the APA and the resource agencies, monitoring plans will be specified in greater detail. 1.2 SCOPE This report presents analyses of mitigation measures that can be used in developing an acceptable fish mitigation plan for impacts resulting in the impoundment zones of the proposed Susitna Hydroelectric Project. Compensation is the _ _1!1&-~st_mitigatio.CL op_tion achievable for impacts in the impoundment _!-QJlCS. Higher priority options, such as avoidance, minimization, rectification and reduction, are considered infeasible. Three measures for providing compensation for the expected losses of fish habitats and fishery resources in the impoundment zones are evaluated in this report. Based on input from resource agencies, acquiring public access to the Susitna River and its tributaries below Devil Canyon is the preferred compensation measure (ADF&G 1984). Secondary priority is given to habitat modifications or improvements in the middle Susitna River (between Devil Canyon and Talkeetna) that would enhance important resident species (rainbow trout or Arctic grayling) or important sport species of salmon (chinook or coho salmon). The third compensation measure evaluated is the hatchery propagation and stocking of Arctic grayling. Final decisions on the strategy to be 4 implemented will be made through negotiations between the APA and resource managers. 5 2.0 PROJECT DESCRIPTION AND OPERATION In April 1985, the APA proposed that the Susitna Hydroelectric Project be changed from a two-dam, two-stage development to a two-dam, three stage de velopment (APA 1985). Under the proposal, a 705 ft high material-fill dam will be built during Stage development at Watana (RM 184). Stage 2 includes the construction of a 646 ft concrete-arch dam, with a fill saddle dam at Devil Canyon (RM 152). Stage 3 development will raise the Stage 1 Watana dam r,-: i · ~ ___ __., -l y ·'-- 180 ft to a crest height of 885 ft. Stage 2/'and 3 developments will result in t '-~ .~ <i.+-~ ~ the two-dam system described in the' FERC license application (APA 1983a, b). "' -r~ ·t-2.. d .. _ _, I ............. ~ t \ (M ~ \yia_~c... .. t : .(. ' Under the present schedule, construction of the Stage 1 Watana dam will begin in 1990, with all turbines on-line for power production by 1997. The Stage 2 development will begin at Devil Canyon in 1995 and be completed by 2002. The Stage 3 Watana Dam construction will commence in 2002 and be finished by 2008. 2.1 STAGE -WATANA RESERVOIR The Stage 1 development of the Watana dam (RM 184) will impound a reservoir of approx i mately 4.2 million acre-feet, with a surface area of 21,000 acres (APA 1985). The normal maximum water surface elevation (WSE) will be 2000 ft above mean sea level (MSL), while the norma l minimum water level will be elevation (el.) 1850. At el. 2000, the maximum r eservoir depth will be 550 ft, while the mean depth is expected to be about 200 ft. The Stage 1 Watana reservoir will be operated in the store-and-release mode. Under average climatic conditions, the reservoir will be filled to el. 2000 by late August or early September. To meet power production needs, the reservoir wiil be drawn down from October through April. The maximum drawdvwn will be 150 ft and will proceed at an average rate of 0.7 ft per day. The minimum drawdown level of 1850 ft will usu:>1lly occur in late April or early May. The reservoir will be refilled during the summer (May through August) when tributary runoff and glacial meltwater are high. During years of normal climatic conditions, refilling will inc.·ease the WSE 1.25 ft per day. 6 2.2 STAGE 2 -DEVIL CANYON RESER VOIR When the Devil Canyon dam (RM 152) is completed, the Stage I Watana dam will be used primarily for power-peaking and reserve energy production, while the Devil Canyon dam will be operated to meet baseload energy demands. The Devil Canyon reservoir will optimize power production at a normal maximum WSE of 1455 above MSL from November through July (APA 1983a). Drawdown will occur during July, August and early September during average or dry years to meet power production needs and downstream flow releases while the Watana reservoir is refilling. The normal maximum drawdown will be 50 ft, to el. 1405, with refilling occurring during late September and October. In wet years, there will be no need to drawdown the Devil Canyon reservoir. At the normal operating water level of 1455 ft, the Devil Canyon reservoir will have a volume of 1.09 million acre-feet and a surface area of 7,800 acres. The reservoir's maximum depth will be 565 ft, while the mean depth will be 140 ft (APA 1983a). 2.3 STAGE 3 -WATANA RESERVOIR The Stage 3 development of the Susitna Hydroelectric Project will raise the pool of the Watana reservoir 185 ft. The total volume of the Stage 3 Watana resc-rvoir will be approximately 9.47 million acre-feet, with a total surface area of 38,000 acres (APA 1983a). The normal maximum WSE of the reservoir will be el. 2185, while the normal minimum water level is expected to be el. 2065. At el. 2185, the maximum reservoir depth will be 735 ft. The Stage 3 Watana reservoir will operate in the store-and-release mode (APA 1983a). The drawdown and refill cycle will follow a pattern similar to that of the Stage reservoir drawdown. Under average climatic conditions the reservoir will be filled to el. 2185 by late August or early September. Drawdown will occur from October through April, with refilling taking place from May through August. The maximum drawdown will be approx imately 120 ft and will occur at an average rate of 0.5 ft per day. Refilling will increase the water level in the reservoir an average of 1.0 ft per day. 7 The drawdown and refill cycle of the Stage 2 Devil Canyon reservoir with Stage 3 Watana in place is expected to be the same as projected for the Stage I /Stage 2 development. The magnitude, timing and duration of the drawdown and refill cycle of the Stage 2 Devil Canyon reservoir was described in Section 2.2. 8 3.0 FISH RESOURCES IN THE IMPOUNDMENT ZONES Nine species of fish have been observed in the impoundment zones (Table 1). Excluding burbot and lake trout, fish were caught or observed primarily in tributaries, near tributary mouths and in clearwater sloughs. Burbot were captured throughout the mainstem, while lake trout were found in one lake: Sally Lake (ADF&G 1983a). A brief summary of life history information and distribution and abundance data of the fish species observed in the impoundment areas is presented in the following sections (3 .1 through 3.9). 3.1. ARCTIC GRAYLING Arctic grayling are abundant throughout the upper Susitna River basin and are widely distributed in tributary habitats during the summer (ADF&G 198la, 1983a). During the fall, it is suspected that most fish move into the Susitna River mainstem to overwinter, except in tributaries that have fish passage barriers (e.g. Deadman Creek). Fish residing upstream of the waterfall:; in Deadman Creek likely overwinter in deeper pools of Deadman Creek or move into Deadman Lake (Sautner and Stratton 1984). Arctic gr«yling move from the mainstem back into tributaries to spawn in the spring (late April and May). Spent fish were captured in tributaries immediately after spring breakup (ADF&G 1983a). Depending upon the actual timing of spawning, incubation extends from May into June (Morrow 1980). Adult grayling rear in tributaries throughout the summer. However, juvenile grayling rear in natal tributaries and in the mainstem near tributary mouths. Smaller fish are likely excluded from higher quality tributary habitats by the territorial behavior of older, aggressive adults (ADF&G l983b, Morrow 1980). The size of Arctic grayling populations has been estimated in the reaches of the larger tributaries in the impoundment zones (Tables 2 and 3). Based on m a rk and recapture estimates in 1981 and 1982, over 16,300 Arctic grayling (greater than 150 mm in len gth) reside in tributary reaches that will be inundated (ADF&G l983a). Arctic grayling also occur in Sally Lake, which will be inundated by the Stage 3 Watana reservoir. In 1982 attempts were made to estimate the population size of grayling in Sally Lake. However, due to few 9 Table 1. Common and scientific names of fish species observed in the Watana and Devil Canyon impoundment zones. Scientific Name Salmonidae Coreqonus pidschian Oncorhynchus tshawytscha Prosopium cylindraceum Salvelinus malma Salvelinus namaycush Thymallus arcticus Catostomidae Catostomus catostomus Gadidae Lota lota Cottidae Cottus coqnatus Common Name humpback whitefish chinook salmon round whitefish Dolly Varden lake trout Arctic grayling longnose sucker bur bot slimy sculpin Source: ADF&G 1981a, 1983a; Sautner and Stratton 1984 10 1-' 1-' Table 2. Arctic grayling population esti~ates in selected tributaries of the Watana impoundment zone . Estimated Estimated Tributa2Y Estimated Number of River Grayling 1 Miles Inundateg ~rayling in Inundated Beach Tributary Mile per Mil~ Stage 1 Stage 3 Total stage 1 Stage 3 Total Deadman Creek 186.7 1,835 3 2.0 0.7 2.7 3,670 1,285 4,955 Watana Creek 194.1 333 7.8 4.0 11.8 2,597 1,332 3,929 Kosina Creek 206.8 1,232 3.0 1.5 4.5 3,696 1,848 5,544 Jay Creek 208.5 455 2.3 1.2 3.5 1,047 546 1,593 Goose Creek 231.3 791 o.o 1.2 1.2 0 949 949 Oshetna River 233.4 1,103 ~ _l_d 2.2 0 2.427 2.427 Total 15.1 10.8 25.9 11,010 8,387 19,397 1 Modified from ALF&G 1983a. 2 Assumes reservoir levels at probable maximum flood stage: Stage 1 Watana = el. 2020, Stage 3 Wat~na = el. 2200.5. 3 Estimated grayling per mile in Deadman Creek was calculated by ADF&G (1983) for the reach of s~ream below the falls (0.3 mi). Extrapolation of grayling per mile to total length of stream inundated is likely an overestimation of gi-Jling population size. Table 3. Arctic grayling population es t imates in selected tributaries of the Devil Canyon impoundment zone. Tributary River Mile ~ Fog Creek 176.7 Tsusena Creek 181.3 Total Estimated TributafY Miles Inundated 1.3 1.7 Estimated No. of Grayling in Inundated Reach 176 1.000 1,176 1 Assumes reservoir level at probable maximum flood stage • el. 1466. 2 Source: ADF&G 1983a. recaptures of tagged fish, an estimate based on ma rk and recapture was not made. Alaska Department of Fish and Game personnel believe that the population size of Arctic grayling in Sally Lake is in the vicinity of 5,000 fish (ADF&G 1983a). 3.2 BURBOT Burbot are found in mainstem-influenced habitats of the upper Susitna River. To date, they have not been captured in tributaries or lakes that will be inundated. Burbot are relatively sedentary throughout the year, except during the winter when they move to spawning areas (ADF&G 1983b, Morrow 1980). Studies by ADF&G in the middle and lower reaches of the Susitna River indicate . that burbot spawn between January and March under the ice in the mainstem, lf i!t:J in tributary mouths and in slough mouths (ADF&G 1983b).,..-It is assumed that 1;1--I~ /"7 burbot in the upper Susitna River exhibit similar reproductive timing and choice f hp of habitat types. J)o; t.._k During 1982, trotlines were set for burbot at six mainstem and one tributary mouth sites in the Watana Impoundment Zone (ADF&G 1983a). Of the 135 burbot captured, 55 fish were caught in the Watana Creek mouth (RM 194.1), while the remaining fish were captured in the six mainstem sites (Table 4). An attempt was made to estimate the population size of burbot within the impoundment zones by the mark and recapture method in 1982. However, few tagged fish were recaptured during the study and an estimate was not made (ADF&G 1983a). 3.3 DOLLY VARDEN Dolly Varden are found in tributaries throughout the upper Susi ~na River basin during the summer (ADF&G 1983a). However, they are the dwarf stream-resident variety described by Morrow (I 980) that are rarely sought by sport fishermen. 13 -.-----?0 a6 ) ·~ J·i ---1 r · c I (),.,. ) I I )t''-\ (). < I f Table 4. Burbot total catch and catch rates in the Watana impoundment zone, 1982. Mainstem River ~Sltgh Site Mile May June July 1 189.0 --(--) --(--) 3(0.8) 2 191.5 --(--) --(--) 3(0.8) 3 197.8 --(--) 8(2.0) 3(0.8) 3A 201.6 --(--) --(--) --(--) 4 201.2 --(--) 5(1.3) 10(2.5) 5 208.1 --(--) 4(1.0) 2(0.5) Watana 194.1 7(3.5) 17(0.6) 9(0.3) cr. Mouth Total 7(3.5) 34(0.8) 30(0.6) Catch • number of burbot. catch Rate • Catch per trotline day. Dashes indicate no survey. Source: ADF&G 1983a. 1 4 (CS&tgb BAte} Auqust Sept. Total 6(1.5) 7(1.8) 16(1.3) 1(0 .3) 0(0.0) 4(0.~) --(--) --(--) 11(1.4) 6(1.5) 7(1.8) 13(1.6) 7(1.8) 2(0.5) :2 4(1.5) 4 ( 1. 0) 2(0.5) 12(0 .8) 13(0.4) 9(0.4) 55(0.5) 37(0.7) 27(0.6) 135(0.7) In 1981 one Dolly Varden was captured at the mouth of Watana Creek, while in 1~8~ 16 fish were caught in Cheechako, Devil, Watana, Jay and upper Deadman creeks. The total lengths of the captured fish ranged from 120 to 235 mm (ADF&G 198la, 1983a). No population estimate of Dolly Varden in tributaries of the impoundment zones has been done. Few fish (17 total) were caught during two years of extensive field reconnaissance and sampling effort (ADF&G 198la, 1983a). This suggests that Dolly Varden populations are few in number and are scattered throughout the tributaries in the impoundment zones. Although field data are not available to confirm the life history and habitat reqP:rements of Dolly Varden in the upper Susitna River, it is suspected that they are similar to those described by ADF&G in the middle:: Susitna River (ADF&G 1983b) and by Morrow (1980). It is likely that Dolly Varden spawn 10 tributaries in October and November, with incubation occurring until March or April. Rearing likely occurs in tributaries, while overwintering may take place in the deeper pools of tributaries or in the mainstem of the Susitna River. 3.4 LONGNOSE SUCKER Longnose sucker w..:re captured in the upper Susitna tributary mouths in 1981 and 1982 (ADF&G 198la, 1983a). River primarily near Of the 210 adult fish caught, 197 were captured near tributary mouths. The remaining fish were caught at mainstem sites. Watana Creek mouth produced the highest ~atches of longnose sucker in 1981 and 1982, with over half of the total catch occurring at this site. It is suspected by ADF&G that longnose sucker spawn in tributaries in May and June (ADF&G 1983b). Juvenile fish likely rear in tributaries, sloughs of the mainstem and in the mainstem, while adults rear near tributary mouth habitats. Overwintering likely occurs in the mainstem of the Susitna River. 3.5 ROUND WHITEFISH In 1981 and 1982, 38 adult round whitefish were captured near tributary mouths I 5 in the upper Susitna River (ADF&G 198la, 1983a). Due to low catches, life ~. _hi~~o~~ in~~r~~]ion and habitat requirements for this species in the upper Susitna River )~P f equirements of round whitefish this reach of the Susitna River are similar to //(those described by ADF&G in the middle Susitna River (ADF&G 1983b) and by (• Morrow ( 1980). Fish likely spawn in tributaries and mainstem areas in October, while rearing occurs near tributary and slough mouths and in the mainstem. Overwintering likely takes place in the mainstem. 3.6 HUMPBACK WHITEFISH Two humpback whitefish were caught in the upper Susitna River during 1981 and 1982 (ADF&G 198la, 1983a). In 1981 one fish was captured near the mouth of Kosina Creek, while in 1982 a single fish was caught at RM 208 .1 in the mainstem of the Susitna River. Other than its occurrence in the upper Susitna River, little is known of the humpback whitefish distribution and habitat requirements in this reach of river. 3.7 LAKE TROUT Lake trout were captured in Sally Lake in 1981 and 1982 (ADF&G 1981 a, 1983a). They have not been captured in mainstem or tributary habitats. Sally Lake, which is at elevation 2025, will be inundated by the Stage 3 Watana reservoir. A total of 62 lake trout were caught in Sally Lake during gillnet and hook-and-line sampling conducted in 1981 and 1982 (ADF&G 198la, 1983a). The population size of lake trout has not been estimated by the mark and recapture method , due to insufficient recaptures of marked fish. ADF&G persunncl believe that the population size is small, with approximately 1,000 or fewer lake trout inhabiting Sally Lake (ADF&G 1983a). 3.8 SLIMY SCULPIN Sl imy sculpin are apparently distributed in all habitats of the impoundment zones. In 1981, 38 sculpin were caught in the impoundment zon.:s, while in 1982 no record of sculpin catches was reported (ADF&G 198la, 1983a). 16 is li"' ~ --- 3.9 CHINOOK SALMON Salmon are usually prevented from migrating within or upstream of the Devil Canyon dam site (RM 152) by high water velocities in Devil Canyon. However, in 1982, 1983 and 1984 a few chinook salmon were observed upstream of Devil Canyon in four tributaries and tributary mouths. In 1982, 21 chinook salmon were observed in Cheechako and Chinook creeks (ADF&G 1982b). Thirty-four chinook salmon were counted in Cheechako, Chinook and Devil creeks in 1983, while in 1984, 46 fish were observed in Cheechako, Chinook and Fog creeks (Barrett et al. 1984, 1985). Life history information, abundance and distribution data, and habitat requirements for chinook salmon in the Susitna River have been reported by ADF&G (ADF&G 1981b, c, 1982b, 1983b; Barrett et al. 1984, 1985; Schmidt et al. 1984). I 7 4.0 ANTICIPATED IMPACTS 4.1 STAGE -WA I ANA RESER VOIR 4 .1.1 Inundation The Stage 1 Watana reservoir will inundate about 44 miles of the Susitna River from RM 184 to 228. The stream gradient averages about 12 feet per mile in this reach of river (APA 1983a). Steep-walled canyons confine the river primarily to a single channel with intermittent islands. The bed materials consist mainly of large gravels and cobbles. The Stage Watana impoundment will change the physical and chemical characteristics of the Susitna River between RM 184 and 228 to characteristics associated with the lake-like . environment of a large tud,id impoundment. Approximately 15 miles of four named tributaries of the Susitna River will be inundated by the Stage I Watana reservoir. The affected lengths and stream gradients of these tributaries are listed in Table 5. Additionally, numerous smaller unnamed tributaries will have portions of their lower reaches inundated (APA 1983a). A waterfall located about one mile upstream from the mouth of Deadman Creek will be inundated. This waterfall prevents upstream movements of fish into upper Deadman Creek . Removal of this fish barrier will not expand fish populations into new habitat because upper Deadman Creek currently supports a population of Arctic grayling. The potential project impacts on Arctic grayling in upper Deadman Creek are discussed by Bradley et al. ( 1985). Eight lakes will be inundated by the Stage 1 Watana reservoir. These lakes range in size from less than one acre to about 10 surface acres in size. Fish have not been reported to occur in any of these lakes. 4.1.2 Dr a wdown As previously mentioned m Section 2 .1, the Stage Watana reservoir will operate in the store-and-release mode. The reservoir will be drawndown from October through April and refilled from May through August. The normal I 8 ..... \0 Table 5. Topographical features of selected tributaries within the proposed Stage 1 Watana impoundment. Tributary Deadman Creek \~at ana Creek Kosina Creek Jay Creek susitna River Mile 186.7 194.1 206.8 208 .5 Total Approximate Elevation at confluence W/ Susitna 1515 1550 1670 1695 Stream gradient Total length of stream1 inundated (mi) of inundated reach ( ft/mi) 253 2.0 60 7.8 118 3.0 143 _b_1 15.1 1 Assumes reservoir level at probable maximum flood stage = el. 2020. 2 Assumes minimum reservoir level = el . 1850. Source: Adapted from ADF&G 1983 and APA 1985. Approximate length in d2awdown zone (mi) 0.7 2.8 1.5 .L..Z 6.2 Approximate length permanently inundated (mi) 1.3 5.0 1.5 .L...l. 8.9 maximum drawdown zone will be 150 ft . Due to the drawdown and refilling cycle, about 12 miles of the upper Susitna River between RM 216 and 228 will alternate between reservoir and riverine habitat. Reaches of the tributaries will also alternate between reservoir and riverine habitat. The approximate lengths of the four named tributaries in the drawdown zone are listed in Table 5. Three lakes in the Stage Watana impoundment zone will remain permanently inundated. Figure 3 shows a schematic of the Stage Watana Reservoir drawdown refilling cycle. 4.1.3 Water Quality (a) General Description The Stage 1 Watana reservoir will exhibit characteristics similar to deep, glacial lakes in Southcentral Alaska (e.g. Bradley and Eklutna lakes). The dra wdown and refilling cycle, along with the characteristics associated with a deep, turbid reservoir are expected to affect the fish populations that presently are found in the upper Susitna Basin. Water temperatures and suspended sediment and turbidity levels are expected to be altered significantly by the Watana reservoir. These factors are discussed in Sections 4.1.3, b & c. Dissolved oxygen, nutrients, total dissolved solids, conductivity, pH, total hardness, total alkalinity, metals and other water quality characteristics are also expected to change after impoundment; however, similar to the Stage 3 reservoir (APA 1983a), it is anticipated that their levels will not be significantly altered and will not be detrimental to aquatic organisms inhabiting the reservoir. Therefore, they are not discussed in further detail. (b) Temperature Under ex1st1ng conditions, water temperatures in the upper Susitna River range from near 0°C throughout the winter (October through May) to a summer high 0 neav 14 C . Instantaneous water temperatures taken by ADF&G from May thro,•gh mid-September 1982 recorded a low of 0.1°C on May 14 and a high of 0 13.6 C on June 24 (ADF&G 1983a). 20 TO BE INCLliDED IN FINAL REPORT (DATA NOT AVAILABLE) Figure 3 Stage 1 -Watana reservoir water levels ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT Woodwarct-CIJd• Conaultanta HARZA ·EBASCO SUSITNA JOINT VENTURE AND ENTAIX, INC. 2 1 Tributaries of the upper Susitna River exhibit temperature regimes similar to the mainstem. Water temperatures are near 0°C throughout the winter and reach highs above I5°C during mid-summer . From mid-June to mid-October 1982, temperatures were recorded continuously in four tributaries of the upper Susitna River (ADF&G 1983a). The tributary surface water temperatures ranged from 0 to 16 .5°C during this period. The thermal characteristics of the Stage I Watana reservoir will be similar to other deep glacial lakes in Southcentral Alaska (e.g. Bradley and Eklutna lakes). The reservoir is expected to stratify during the summer and winter, while water temperatures will approach isothermal conditions (4°C throughout the water column) in the spring and fall . During mid-summer, when thermal stratification will be the strongest, the maximum surface water temperature is expected to be between 10 and I2°C (Harza-Ebasco 1985a). Temperatures will decrease with increasing depths to 4°C near the reservoir bottom. The depth and strength of this stratification will depend on climatic conditions and will vary from year to year. Stage Watana reservoir temperature simulations can be found in a report by Harza-Ebasco (1985a). As the reservoir's water temperatures cool, the thermal stratification will weaken until isothermal conditions prevail (October or early November). Surface water temperatures will continue to cool until an ice cover forms (late November or early December) (Harza-Ebasco 1985a). The ice cover is expected to last into early May. Due to the winter drawdown cycle of the Stage Watana reservoir, ice along the edge of the impoundment will fracture and remain draped on the bank similar to that expected in the Stage 3 reservoir (AEIDC 1985). During the winter, temperatures near the bottom will remain near 4°C while the surface waters just below the ice cover will be near 0°C. Temperatures at a depth of 100 ft range between 1.5 and 3.0°C during winter (Harza-Ebasco 1985a). Thus, the impoundment will become inversely stratifie d. After spring breakup, the reservoir will warm rapidly due to solar radiation and tributary inflow . 22 The major changes in the thermal regime of the Stage I Watana impoundment are that water temperatures are expected to be warmer in the winter and cooler during the summer compared to natural pre-project conditions and the spring warming and fall cooling rates will be retarded. (c) Suspe nded Sediments and Turbidity Suspended sediment and turbidity levels in the Susitna River are generally high during spring breakup and summer, with reduced levels in the fall. During winter, the Susitna River is typically clear. Suspended sediment values in the mainstem range from winter lows near 10 mg/1 to highs of over 5,000 mg /1 during the summer at Denali Station (RM 289.5), the gaging station nearest the glacially-fed headwaters. Maximum summer concentrations at Gold Creek (RM 138.7) of over 2,000 mg/1 have been observed (APA 1983a). Turbidity values in the mainstem are near zero in the winter. In January and February 1982, values of 1.1 Nephelometric Turbidity Units (NTU) or less were measured by the USGS at Gold Creek (RM i 38.7). Turbidity levels over 700 NTU have been measured at Vee Canyon (RM 223) during July (APA 1983a). Turbidity levels in tributaries of the upper Susitna River are generally low (20 NTU or less) throughout the year. In these clearwater streams, peak turbidity and suspended sediment levels occur during spring breakup and during high flows associated with heavy rainfall events. The Oshetna River is an exception to this, as its headwaters or i ginate from glaciers. In 1982 turbidity valu es in selected tributaries of ';he upper Susitna River ranged from near zero in all tributaries sampied to 42 NTU in the Oshetna River (ADF&G 1983a). The Stage Watana reservoir will change the naturally-occurring suspended sediment and turbidity levels and patterns. Levels in the mainstem will decrease during the summer compared to natural conditions due to the settling out of most (80 percent or more) of the suspended sediments as the sediment-laden Susitna River enters the reservoir. However, the smaller-sized sediments (particle diameters of 4 microns or less) are expected to remain in suspension, causing the reservoir to be turbid. The turbid reservoi r will increase the summer turbidity and suspended sediment levels in the habitats 23 that were previously clearwater tributaries. The reservoir will remain turbid throughout the year. Thus, the natural clearwater conditions that prevail in the mainstem and tributary habitats during the winter will be altered. Slumping of reservoir walls and resuspension of shoreline sediments will create localized increases in suspended sediment and turbidity. The dra wdown and refilling cycle will tend to aggravate the slumping of reservoir walls (APA 1983a). Most of the suspended sediment load of the Susitna River will settle O;Jt as the river enters the reservoir. This process will cause the formation of a delta at the upstream end of the reservoir. The location and extent of the delta will vary with the dra wdown and refilling cycle of Watana and stream flows of the Susitna River. During drawdown, the Susitna River will cut through the delta and transport sediments farther into the impoundment. Although the tributaries to the Watana reservoir are generally clearwater streams, they can transport stream bed materials during spring breakup and periods of heavy rainfall. Therefore, it is expected that small deltas may form at the mouths of tributaries as they enter the reservoir. However, the deltas are not expected to impede fish movements into and out of tributaries. The location of tributary deltas will vary with the drawdown and refilling cycle. The most important change in turbidity levels in the reservoir is that clearwater tributary habitats will be inundated with turbid water, increasing turbidity levels throughout much of the year. 4 .1.4 Effects on Fish The Stage 1 Wa tan a reservoir is expected to significantly affect fish populations in th..: impoundment area. Inundation, the drawdown and refilling cycle, the reservoir's thermal regime and suspended sediment/turbidity levels are expected to be the dominant forces in altering habitats and subsequently affecting the populations of fish in those habitats. The anticipated impacts on species/life stages are described by the habitat types in which the anticipated impacts will occur. 24 (a) Tributary Habitat (i) Arctic grayling The spawning, incubation and rearing life stages of Arctic grayling will likely be adversely affected by the Stage 1 Watana reservoir. Spawning habitat will be lost in the reaches of tributaries inundated by the impoundment, because it is expected that grayling will not utilize the turbid reservoir for spawning. Grayling usually select spawning sites in lotic habitats (Morrow 1980). Spawning normally takes place during May which is when the reservoir will be drawn down. If the timing of spawning coincides with maximum reservoir drawdown, about 9 miles of spawning habitat in the larger, named tributaries would be lost (Table 5). Spawning will likely occur in the reaches of tributaries within the drawdown zone. However, incubation success is expected to be low due to the refilling of the reservoir. Rising water levels will progressively inundate reaches of tributaries in the drawdown zone. Streambed materials carried downstream by the high flows of breakup will be deposited at the mouths of tributaries. The deposition of sediments will move upstream with rising water levels and cover spawning areas, which will likely cause mortalities on developing embryos. During May and June (the approximate period of grayling spawning and incubation) the reservoir's water level will rise 50 to 55 f t. Thus, in years when the reservoir is at maximum drawdown (1850 ft) in late April, embr yo s spawned below el. 1905 would be inundated prior to hatching. Rearing habitat for Arctic grayling in the impoundment will likely be limited to the clearwater plumes near tributary mouths. Arctic grayling are not expected to utilize other areas in the reservoir as grayling are not found in lakes with turbidity levels similar to those anticipated in Watana (Russell 1980). Some dis placed grayling will likely use rearing habitats in tributary reache~ above the reservoir water levels. However, rearing habitats in tributaries are likely already occupied, as indicated by the high densities of grayling per mile (323-1835) reported by ADF&G (1983a). Thus, important tributary habitat will be lost, reducing Arctic grayling populations in the upper Susitna River. It is estimated that the mid -summer population size of Arctic grayling inhabiting 25 tributary reaches inundated by the Stage 1 Watana reservoir is at least 11,000 fish greater than 150 mm in length (Table 2). Most Arctic grayling in the upper Susitna River apparently overwinter in the mainstem, although it is likely that some may remain in tributaries throughout the winter. the warmer temperatures In either case, overwintering conditions will likely improve due to water temperatures in the reservoir. Present winter water in the mainstem and tributaries are near 0°C. Winter temperatures at a depth of !00 ft in the Watana reservoir will be in the range 0 of 1.5 to 3.0 C (Harza-Ebasco 1985a). The warmer water temperatures may increase the overwintering survival of fish in the impoundment, as it has been noted that fish are attracted to warmer water temperatures during winter (U meda et al. 1981). Table 6 summarizes the anticipated impacts of the Stage 1 Watana reservoir on the life stages of Arctic grayling inhabiting tributaries in the impoundment area. The spawning, incubation and rearing life stages will likely experience adverse impacts. Although overwintering habitat will likely improve, it is not expected to offset losses expected during the other life stages. (ii) Dolly Varden The Stage 1 Watana reservoir will likely have insignificant effects or. Dolly Varden populations in tributaries of the upper Susitna River. Dolly Varden occupy a wide range of habitat types in Southcentral Alaska, including glacial lakes ;•ith a wide range of water quality (Russell 1980). Thus, it is expected that Dolly Varden will occupy the Stage I Watana reservoir throughout muc-'1 of the year. Dolly Varden spawn in tributaries during the fall (October to November) (Morrow 1980). After impoundment, it is likely that they will continue to use tributaries for spawning. Dolly Varden densities in the upper Susitna 8asin appear to be quite low, thus, spawning habitat above the impoundment water level is expected to be available as it is unlikely that all spawning habitat is presently utilized. Since Dolly Varden spawn in the fall when the reservoir's water levels will be stable or decreasing, incubating embryos will not be inundated by rising water levels. 26 Table 6. Summary of selected species abundance, sport value and sensitivity to habit~t alteration in tributary habitats of the proposed Stage 1 watana impoundment zone. Species Arctic grayling Dolly Varden Life stage spawning incubation rearing overwintering spawning incubation rearlng overwintering 1 1 • low, 2 = moderate, 3 = high. Abundance in tributary habitat1 3 3 3 1 1 1 1 1 Sport valu! of species 3 3 3 3 1 1 1 1 Sensitl.-ity of species/ life stage to habitat alteration2 3 3 3 0 0 0 1 0 2 0 = no predicted change or, may be positive influence; 1 ~ low; 2 ~ moderate; 3 = high. Refer to t~xt for discussion of species sensitivity to potential impacts. Dolly Varden will likely utilize the Stage 1 Watana reservoir during the summer for rearing. However, turbid conditions and the drawdown j refilling cycle are expected to limit the development of littoral areas and limit productivity of the impoundment. These conditions will likely restrict the distribution of most fish in the reservoir to the clearwater plumes of tributary inflow. As discussed previously, it is expected that overwintering conditions in the Stage Watana Reservoir will improve over those that presently occur in tributaries and the mainstem. Dolly Varden will likely utilize the reservoir during the winter. The anticipated effects of the Stage Watana Reservoir on Dolly Varden populations in tributaries are summarized in Table 6. (b) Mainstem Habitat (i) Burbot Burbot occupy the mainstem of the upper Susitna River throughout the year. After impoundment, mainstem habitats will be eliminated and replaced by a turbid lake-like impoundment. Since burbot are found in glacial lakes in Southcentral and Southwestern Alaska (Bechtel Civil and Minerals, Inc. !981; Russell 1980), they will likely utilize the Stage 1 Watana reservoir year-round. The winter drawdown of the Stage l Watana reservoir is expected to affect the incubation success of burbot in the impoundment. In lakes, burbot usually spawn in mid-winter (January to early March) in relatively shallow water (20 ft or less) (Morrow 1980). The Stage l Watana reservoir will be dra wndown from November to May at an average rate of 0 .7 ft per day. Thus, embryos in shallow water will become dewatered and freeze. This will substantially reduce the recruitment to burbot populations occupying the impoundment. Some burbot in the impoundment may move into the upper Susitna River to spawn. The rearing and ov e rwintering life stages of burbot are not expected to experience any adverse impacts from the project. Burbot will likely be distributed primarily near the clearwater plumes of tributary inflow, due to the 28 expected abundance of prey species in those areas. Overwintering condit ions may improve after impoundment, due to the warmer win t er temperatures. Table 7 summarizes the anticipated impacts of the Watana reser v uir on the life stages of burbot. (ii) Arctic grayling Some juvenile Arctic grayling use mainstem areas near tributary mouths for summer rearing. These fish are apparently excluded from tribut:uy habitats by t he territorial behavior of larger, older f ish (ADF&G 1983b, Morrow 1980). It is expected that the Stage I Watana reservoir will not have signifi cant effects on these fish as replacement habitat will likely exist near the tributary mouths in the reservoirs. Most Arctic grayling in upper Susitna R i ver tributaries apparently move into the mainstem for overwintering. Overwintering conditions for grayling under existing and with-project conditions have been discussed rre v iousl y (Section 4.1.4). It is likely that overwintering conditions will improve under project operation. A summary of the expected impacts of the Stage 1 Watana reservoir on Arct ic grayling in mainstem habitats is presented in Table 7. (iii) Dolly Varden Dolly Varden may utilize mainstem habitats for overwinter i ng. As disc ussed previously, over wintering c onditions will likely improve under pro ject o perat io n due to warmer water temperatures of the reservoir. Thus. i f Do ll y Varden d o overwinter in the ma i n s tem, conditions are expected t o improve under with-project operation (Table 7). (c) Lake Habitat None of the lakes inun da t e d by the Stage 1 Wat a na reservoir ha ve been reported to contain fish . Most of the lakes are small, perched tundra lakes. 29 Table 7. Summary of selected species abundance, sport value and sensitivity to habitat alteration in mainstem habitats of the proposed Stage 1 Watana impoundment zone. Species Bur bot Life stage spawning incubation rearing overwintering Abundance in 1 mainstem habitat 1 1 1 1 Sport va1uy of species 1 1 1 1 Sensitivity of species; life stage to habitat alteration2 0 3 0 0 w o Arctic grayling rearing overwintering 1 3 3 3 0 0 Dolly Varden overwintering 1 1 0 1 1 = low, 2 = moderate, 3 = high. 2 O = no predicted change or, may be positive influence; 1 • low; 2 = moderate; 3 = high. Refer to text f or discussion of species sensitivity to potential impacts. Therefore, the inundation of lakes by the Stage 1 Watana reservoir will likely have insignificant effects on fish. 4.2 STAGE 2 -DEVIL CANYON RESERVOIR 4 .2.1 Inundat i on The Devil Canyon reservoir will inundate about 31 miles of the Susitna River from RM 152 to 183. From Watana (RM 184) downstream to Devil Creek (RM 161) the stream gradient averages 11 ft per mile, while between Devil Creek and Devil Canyon (RM 152) the gradient increases to 31 ft per mile (APA 1983a). Steep canyon walls confine the river to a single channel throughout most of the river between Devil Canyon and Watana. A b out six miles of the lower reaches of five named tributaries will be inundated (Table 8), plus the lower reaches of numerous smaller, unnamed tributaries. Inundation will change the physical and chemical characteristics of the riverine hab i tats to those associated with a large, turbid impoundment. Many of the tributaries in the Devil Canyon impoundment area are characterized by high stream gradients with occasional waterfalls. Cheechako, Devil and Tsusena creeks all contain waterfalls. However, none of these waterfalls will be inundated and would still function as barriers to upstream fish passage after impoundment. One five-acre lake will be filled by the saddle dam during constru c tion (APA 1983a). No lakes will be affected by impo undment of the Devil Can yo n Reservoir. 4.2.2 Ora wd ow n Due to the nature of the two-dam system, Devil Canyo'l impoundment w i ll operate at full pool (1455 ft) for most of the year (APA 1983a). During wet years there w ill be no need to drawdown the reservoir. However , during average and dry years, drawdown w i ll occur during Jul y, Augu st and early S~ptember . The drawdown will help meet power production ne e ds and downstream flow releases while the Stage 1 Watana reservoir is refilling. The 3 1 w 1\) Table 8. Topographical features of selected tributaries within the proposed Devil Canyon impoundment. Tributary Susitna River Mile Cheechako Cr. 152 .4 Chinook Cr. 157.0 Devil Cr. 161.4 Fog cr. 176.7 Tsusena cr. 181.3 Total Approximate elevation at confluence wH:h Susi tna 920 1065 1200 1375 1435 Stream gradient Total length of stream1 inundated (mi) of inundated reach ( ft/mi) 321 1.7 308 1.3 176 1.5 72 1.3 82 0 .4 6 .2 1 Assumes reservoir level at probable maximum flood 2 Assumes minimum reservoir level = 1405 ft MSL. stage = 1466 Source: ADF&G 1983a. Approximate length in d2awdown zone (mi) 0.2 0.2 0.3 0.9 0.4 2.0 ft MSL. Approximate length permanently inundated (mi) 1.5 1.1 1.2 0.4 Q.& 4.2 normal maximum drawdown zone for Devil Canyon is expected to be 50 ft. Thus, the magnitude, timing and duration of drawdown for Devil Canyon reservoir is quite different from the Stage 1 Watana drawdown (~..;ction 4.1.2). About five miles of the Susitna River between RM 178 and 183 will alternate between reservoir and riverine habitat due to the drawdown of Devil Canyon reservoir. Reaches of tributaries within the impoundment area will also alternate between reservoir and riverine habitat. The approximate lengths of the five named tributaries in the drawdown zone are listed in Table 8. A schematic of the drawdownjrefilling cycle in the Devil Canyon reservoir is shown in Figure 4. 4.2.3 Water Oualjty (a) General Description The water quality in the Devil Canyon reservoir will be similar to that in the Stage Watana reservoir (Section 4.1.3). The impoundment is expected to significantly alter water temperatures and suspended sediment and turbidity levels of mainstem and tributary habitats. Other water quality parameters are not expected to change significantly (Section 4.1.3). (b) Temperature Baseline water temperature conditions in the upper Susitna River and its tributaries were described i n Section 4.1.3(b). The temperature regime of the Devil Canyon reservoir is expected to be similar to Stage 1 Watana reservoir. The Devil Canyon reservoir will experience weak summer and winter thermal statifications, interrupted by isothermal conditions in the fall and spring. Water temperatures during the c;ummer 10 the Devil Canyon reservoir are expected to be cooler in comparison to pre-project conditions, while winter temperatures will be warmer than natural conditions. The fall cooling and spring warming periods are expected to shift, lagging behind natural conditions. The Devil Canyon reservoir temperature simulat ions are illustrated in reports by Harza-Ebasco ( 1985a, 1985b). 33 146'0 I I ~MAX~UM I I I / I I v--// I "t\ ,~MEAN] ~ I 1450 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 I \ i 1440 /t.+-MIN~MUM 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 I I \ . I i I I I 1430 I I I l I I I ·I : I !MINI~M_u I I I I ! ll I I I \ I I i 1420 I I I \I I I I I /I I I . I \ i I I I I I 1 4 1 0 VI I I I i ""' NOTE: RESERVOIR LEVELS SHOWN ARE BASED ON MONTHLY ! AVERAGE V ALUES ANO ARE PLOTTED ~ T MID· MONTH 1400 I I I I I l OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT I Figure 4 Stage 2 -Devil Canyon water levels. 2020 simulation case E-VI ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT Woodward-Clyde Conaultanta HARZA ·EBASCO AND S U S I T N A ,• 0 I N T V E N T U R E ENTRIX, INC. 34 Due to its smaller size (7,800 surface acres, 1.09 million acre-feet) compared to the Stage 1 Watana reservoir (21 ,000 surface acres, 4.2 million acre-feet), the Devil Canyon reservoir will likely respond to meteorological conditions more rapidly, and in particular will be more suscepti ble to wind mixing. The maximum surface water temperatures in the Devil Canyon reservoir are expected to be in the range of 10 to 12°C in August. During winter, an ice cover is expected to form on the Devil Canyon reservoir by l ate November, lasti ng until early May (Harza-Ebasco 198Sa). Predictions indicate that winter water temperatures will be in the range of 2 to 4°C at a depth of SO ft (Harza-Ebasco 198Sa). (c) Susoended Sediments and Turbidity Suspended sediments of less than 4 microns in diameter will enter the Devil Canyon reservoir from the Stage Watana reservoir. Only a small percentage of the suspended sediment is expected to settle out. Thus, suspended sediment levels will generally reflect those occurring in the Stage I Wa t ana reservoir. Due to the settling out of most sediments in the Stage 1 Watana reservoir, an extensive delta will not form at the upstream end of the Devil Canyon reservoir. Small deltas will likely form at the mouths of tributaries, simila r to those expected in the Stage I Watana reservoir. Some slumping of reservoir walls and resuspens ion of shorel i ne sed i ment will occur, particularly during reservoir drawdown. However, since the overburden layer is shallow, slumping and sediment entrainment should not create significant problems. Thus, increases in suspended sediment and turbidicy levels will be localized and short-term. Turbidity levels in the Devil Canyon reservoir are expected to follow the pattern and range of levels in the Stage 1 Watana reservoir. Turbidity values are expected to be lowest during the spring and increase during la te s u mmer and early fall. 35 The most important change in turbidity levels from natural conditions is that clearwater tributary habitats will be inundated by turbid water, in c reasing turbidity levels throughout much of the year. 4.2.4 Effects on Fish The Stage 2 Devil Canyon reservoir will affect fish populations inhabiting the upper Susitna Basin. Inundation, drawdown and refilling, and the reservoir's thermal regime and suspended sediment/turbidity levels are expected to be dominant forces in altering habitats. The anticipated impacts on species/life stages are described by the habitat types in which impacts will occur. (a) Tributary Habitat The major alteration of tributaries is the inundation of these clearwater !otic habitats with a turbid lake-like environment. Anticipated impacts to fish species in tributary habitats are expected to be similar to those presented in Section 4.1.4(a) for the Stage I Watana reservoir. (i) Arctic grayling Arctic grayling are not expected to spawn in the turbid reserv oir, as the y prefer !otic habitats. The Devil Canyon reservoir will be at full pool (el. 1455 ) during the grayling spawning and in cubation periods (May-June ). Thus, abo ut six miles of habitat in the larger, named tributaries would be lost due to inundation (Table 8). Because the reservoir will be at full pool, any spawning that occurs in tributaries upstream of the reservoir's water level will not be affected by the drawdown and refill i ng cycle. Rearing conditions for Arctic grayling in the reservoir will be similar to th ose in the Stage I Watana reservoir (Section 4.1.4). It is expected that most of the 1,~00 grayling residing in tributaries within the impoundment area (Table 3) wil l be displaced and lost. The De v il Canyon reservoir will likel y improve o verwinteri n g c o ndit ions f o r Arctic grayling in the impoundment area . The winter water temperatures are 36 expected to be in the range of 2 to 4°C at a depth of 50 ft (Harza-Ebasco 1985a). Thus, warmer than natural temperatures (near 0°C) will likely improve the overwintering survival of fish. Table 9 summarizes the impacts of the Devil Canyon reservoir on the life stages of Arctic grayling inhabiting tributaries within the impoundment area. (ii) Dolly Varden The Devil Canyon reservoir is expected to have insignificant effects on Dolly Varden populations in the upper Susitna Basin. Dolly Varden are expected to utilize the Devil Canyon reservoir throughout much of the year. Dolly Varden will likely spawn in tributary reaches above the reservoir's water level after impoundment. Some incubating embryos ma y be affected by the refilling cycle. Spawning occurs in October and November, which is when the reservoir will be filling du-ing normal or dry years. Embryos spawned in the drawdown zone will likely experience higher mortalit y due to inundation and siltation (Section 4.1.4). The Devil Canyon reservoir is not expected to provide favorable conditions for rearing fish. The steep walls ar.d turbidity will inhibit the development of a littoral area and productivity of the reservoir. Similar to the Stage I Watana reservoir, it is expected that most fish will be distributed near the inflow of tributaries. Table 9 summarizes the anticipated effects of the De v il Canyon reserv o ir o n Dolly Varden populations in tributary habitat. (b) Mainstem Habitat (i) Burbot Burbot are found (Russell 1980) and throughout the year. in glacial lakes in Southcentral and Southwestern Alas ka are expected to utilize the Devil Canyon reservoir Unlike the Stage 1 Watana r eservoir, the Devil Canyon 37 w (X) Table 9. summary of selected species abundance, sport value and sensitivity to habitat alteration in tributary habitats of the proposed Devil canyon impoundment zone. Species Arctic grayling Dolly Varden Life stage spawning incubation rearing overwintering spawning incubation rearing overwintering 1 1 = low, 2 = moderate, 3 = high. Abundance of species in tributary habitat1 3 3 3 1 1 1 1 1 Sport valuy of species 3 3 3 3 1 1 1 1 Sensitivity of species/ life stage to habitat alteration2 3 3 3 0 1 0 1 0 2 0 = no predicted change or, may be positive influence; 1 • low; 2 = moderate; 3 = high. Re f er to text for discussion of species sensitivity to potential impacts. reservoir's water level will be stable during winter. Thus, the drawdown and refilling cycle of the reservoir will not affect burbot embryo incubation. No significant impacts are anticipated for burbot inhabiting the Devil Canyon reservoir (Table !0). (ii) Arctic grayling No significant impacts are anticipated for Arctic grayling in mainstem habitats of the Devil Canyon reservoir (Table 10). Conditions are expected to be similar to those dicussed in Section 4.1.4. (iii) Dolly Var.Q.m The anticipated effects of the Stage I Watana reservoir on Dolly Vardc=n in mainstem habitats (Section 4 .1.4[b)) are expected to be the same for the Devil Canyon Reservoir. No significant impacts are foreseen. (iv) Chinook Salmon A few chinook salmon migrate upstream of Devil Canyon (RM 152) to spawn . Construction of the Devil Canyon dam will prevent chinook salmon from utilizing habitats upstream of the dam site. 4.3 SJ:M:!E 3 -WATANA RESERVOIR 4.3.1 Inundation The Stage 3 Watana reservoir will inundate an additional II miles of Susitna River from RM 228 to 239. Approximately 10.8 miles of six named tributaries will be inundated by the Stage 3 reservoir (Table 11). The total lengths of the named tributaries inundated by both Stage 1 and Stage 3 is about 26 miles. Additionally, numerous, unnamed tributaries will also be affected by the Stage 3 impoundment. 39 Table 10 . Summary of selected species abundance, sport value and sensitivity to habitat alteration in mainstem habitats of the proposed Devil Canyon impoundment zone. Species Burbot Arctic grayling Dolly Varden Life stage spawning incubation rearing overwintering rearing overwintering overwintering 1 1 • low, 2 = moderate, 3 = high. Abundance of species in mainstem habitat1 1 1 1 1 1 3 1 Sport valuy of species 1 1 1 1 3 3 1 sensitivity of species/ life stage to 2 habitat alteration 0 0 0 0 0 0 0 2 0 = no predicted change or, may be positive influence: 1 = low: 2 • moderate: 3 = high. Ref e r to text for discussion of species sensitivity to potential impacts. Ta b le 11 . To pographi c al f e atu res o f s elec t ed tr i but a ries within the proposed Stage 3 Watana i 11 pound11ent . App r o xi ma t e e levation Stream gradi e nt Appro x i11 a te length Approxi 11ate l e ng t h Sus i tna of con fl ue n c e with of inunda ted l e nsth o f st r·e a lll i ?undated ~•1 1 in d r~w do wn pe r ma nently Tr i butary Ri ve r Mile Su s i tna reach ( ft/m i ) Stage Stag e 3 Total zone ( 111 1 ) i nundat e d (II i) Deadman Creek 186.7 1515 253 2 .0 0 .7 2 .7 0 .5 2 .2 60a a Wa ta na C;e e k , 94., 155 0 7 .8 0.7 8.5 0 .0 8 .5 c ~~~: 0.0 1.2 1 2b 1.2 0 .0 East Fo r k N/A 2 06 0 c • b We st Fork N/A 2 060 0 .0 2 .1 2. 1 2 .0 0 .1 ~ Ko si na Cr eek 206 .8 1670 118 3 .0 1.5 4 .5 1.1 3 .4 ..... Jay Creek 208.5 16 95 143 2 .3 1.2 3 .5 0.9 2 .6 Goo s e Cree k 231 .3 2060 114 0 .0 1.2 1.2 1.1 0 .1 Osh e tna Ri v er 233 .4 2110 41 .JL..Q ..1..:1. ..1..:1. u .JL..Q To ta l 15 . ~ 10 .8 25 .9 9.0 16 .9 As sume s r eservoir l e vel a t p robable maxi mum f l ood s tage e l . 22 00.5. 2 As s umes mi n imu m rese r vo i r l e v e l e l. 206 5 . a Wa t a na Cr eek below for ks . b Wa tana Creek above fo r ks. c Elevat ion a t con f luence of Watana Cr eek f orks . Moditied f r om ADF&G 1983 a . Twenty-three lakes will be inundated by the addition of the Stage 3 Watana development. Most of the lakes are relatively small, as 22 lakes are less than 10 surface acres. Sally Lake, with a surface area of 63 acres and a maximum depth of 27 ft, is the largest lake affected by the Stage 3 Watana Reservoir. Sally Lake is located on the north side of the Susitna River near the mouth of Watana Creek at an elevation of 2025 ft. 4.3.2 Drawdown The Stage 3 Watana reservoir will be operated similar to Stage 1 Watana: the store-and-release mode. The Stage 3 reservoir will be drawndown from October through April and refilled from May through August. The normal maximum drawdown zone will be 120 ft. The drawdownjrefilling cycle is shown in Figure 5. Due to the drawdown and refilling cycle, about 9 miles of the upper Susitna River between RM 230 and 239 will alternate between reservoir and riverine habitat. Reaches of tributaries will also alternate between reservoir and riverine habitat. Table 11 shows the approximate lengths of the six, named tributaries in the drawdown zone. Most lakes, including Sally Lake, will remain inundated during drawdown. 4.3 .3 Water Quality The water quality associated with Stage 3 Watana reservoir is expected to be similar to that of Stage Watana reservoir. The only significant change expected at this time is for winter water temperatures in the Stage 3 impoundment to be l to l.5°C warmer than the Stage I reservoir (APA 1985). This is attributed the larger reservoir volume and longer retention time associated with the Stage 3 reservoir. Ice formation on the Stage 3 reservoir will occur about mid-November and last until euly May (Harza-Ebasco 198~a). 4.3.4 Effects on Fish The Stage 3 Watana reservoir will alter habitats and affec! fish populations similar to the Stage I Watana reservoir. Inundation, drawdown, water 42 2200 2190 2180 2170 2160 2150 2140 2130 2120 2 1 10 2100 2090 2080 2070 2060 I T I I I I ~,r-NORMAI.. MAXIMUM POOL El... 2185 I J I ~ I I I i_Ll I I I "' I l--- ""'') I I I I 1 I l i I I 1\ I I I I I I I " ~\ I I I I I I I v I I I I : I I I I ' I I 1'\ i I I i ' I /I I I I I I 1\\ I I I ?I I I I I I i L_ 1\ ' i i i ~ I I \ 1\\ I I I I !/ ;0 I I ' "-.j \I I ~ I I \ I I :I l I I I '\ I I 1\ i I i I ; ! ~ I I I I IJ : I i ~", I 1\\ I I I I :1 I I J I ' I I ' \ ;\I I v /I I ~, I I '\ \\'~!/ I I I i ~, I I 1/ I '\ ~ /; J l I '\ I ' "' ! ., I I I I i l ", ' I ! :/ ! I I .._ I I I I I I l ~f ! I NOTE : FIESERVOIR LEVELS SHOWN I I ARE BASED ON MONTHLY I I I I I ~ ' I I ' AVERAGE VALUES ANO ARE I l I I PLOTiEO AT MlcrMONTH I I I I 1 I I I MAXIMUM MEAN MINIMUM OCT NOV DEC JAN FEB MAR A PR MAY JUN JUL AUG SEPT Figure 1\ Stage 3 -Watana reservoir water levels. Watana and Devil Canyon operating. 2020 simulation case E-VI AlASKA POWER AUTHOR ITY SUSITNA HYOROE'.ECTRIC PROJECT Woodward-Clyde Conault.nta HARZA ·EBASCO SUSITNA JOINT VENTURE AND ENTAIX , INC. 43 temperatures and turbidity/suspended sediment levels will continue to be the dominant forces affecting habitats and fish populations. Ant i cipated impacts associated with completion of the Stage 3 Watana reservoir are discusst:d by the habitats in which they will occur. (a) Tributary Habitat Arctic grayling and Dolly Varden inhabiting tributary reaches inundated by the Stage 3 Watana reservoir will be affected in ways described in Section 4.1.4 for the Stage 1 Watana reservoir. No significant impacts are expected for Dolly Varden. However, inundation of almost 11 additional miles of the larger named tributaries will affect summer habitat utilized by an estimated 8,400 Arctic grayling (Table 2). It is likely that most of the graying inhabiting clearwater tributaries inundated by the reservoir will be displaced and lost. (b) Mainstem Habitat Anticipated impacts of the Stage 1 Watana reservoir on fish inhabiting the mainstem were discussed in Section 4.1.4. It is expected that the Stage 3 Watana reservoir will affect mainstem habitats and fish populations in similar ways. The dewatering of burbot embryos spawned in shallow areas of the reservoir will continue to reduce recruitment to burbot populations of the upper Susitna River. (c) Lake Habitat (i) Arctic grayling Arctic grayling occur in Sally Lake, which will be inundated by the Stage 3 Watana reservoir. The effects of the impoundment on grayling are expected to be similar to those discussed previously (Section 4 .1.4}. The spawning, incubation and rearing life stages will likely experience adverse impacts (Table 7). 44 (ii) Lake Trout A small population of lake trout occurs in Sally Lake. Lake trout from Sally take are expected to survive in the Watana reservoir as lake trout are fonnd in glacial lakes in Southcentral Alaska (Becht.:: I Civil and Minerals, Inc. I S81, Russell 1980). Lake trout will likely spawn in the Stage 3 Watana reservoir. However, incubating embryos will be affected by the drawdown cycle. Lake trout usually spawn from late September to November at depths ranging from 3 to II 0 ft (Morrow 1980). Drawdown (November to May) in the Stage 3 Watana reservoir will average 0.5 ft/day. As a result, embryos incubating in the upper 50 to 60 ft of the reservoir will be dewatered by March I (the approximate end of the incubation period), causing incubation success to be low in the drawdown zone. The drawdown/refilling cycle and turbidity levels of the Watana reservoir are expected to limit the development of a littoral zone and restrict the productivity of the Stage 3 impoundment. Therefore, it is likely that rearing conditions will not be favorable in much of the reservoir. However, the clearwater plumes of tributaries are expected to provide favorable rearing habitats for fish. Lake trout may frequent these areas because of the availability of prey. It is expected that the growth rate of lake trout will be low because of the expected low productivity of the impoundment. Overwintering conditions in the Watana reservoir will likely have insignificant effects on lake trout. The expected effects of tho Stage 3 Watana impoundment on lake trout populations are summarized in Table 12 . 45 ,eo. 0'1 Table 12. Summary of selected species abundance, sport value and sensitivity to habitat alteration in lake habitats of the proposed Stage 3 Watana impoundment zone. Species Life stage Arctic grayling spawning incubation rearing overwintering Lake trout spawning incubation rearing overwintering 1 1 -low, 2 = moderate, 3 = high. Abundance of species in lake habitat 2 2 2 2 1 1 1 1 Sport valuy of species 3 3 3 3 3 3 3 3 Sensitivity of species/ life stage to 2 habitat alteration 3 3 3 0 0 2 1 0 2 o • no predicted change or, may be positive influence; 1 • low; 2 • moderate; 3 = high. Refer to text for discussion of species sensitivity to potential impacts. 5.0 SELECTION OF EVALUATION SPECIES All three mitigation policies (APA 1982, ADF&G l982a and USFWS 1981 ) imply that project impacts on certain sensitive fish species will be of greater concern than changes in distribution and abundance of less sensitive species. Sensitivity can be rela ted to high human use value as well as susceptibility to change because of project impacts. Statewide policies and management approaches of resource agencies suggest that concern for fish and wildlife species with commercial, subsistence and other consumptive uses is greater than for species without such value. These species are often numerous, and utilize a wide range of habitats, as well as having high human use value. Such characteristics often result in these species being selected for detailed evaluation when their habitats are subjected to alterations. In the impoundment zones, Arctic grayling are abundant and widespread in tributary habitats during summer, and reside in the mainstem during winter. This species has a high human value, as it is highly prized by sport fishermen. Grayling populations in the impoundment zones contain fish that are of trophy size (Schmidt and Stratton 1984). Based on impact assessments presented in the license application (APA l983b) and in Section 4.0 of this report, it is likely that the impoundments will not provide suitable spawning, incubating or rearing habitats for Arctic grayling. Anticipated impacts to grayling habitats are considered unavoidable, as the inundation of tributary habitats by the turbid impoundments is a necessary part of the project design and operation. As a result of the expected loss of grayling habitats and ant i cipated reduction in populations, the Arctic grayling is selected as the primary e v aluation species in the impoundment zones. It is the APA's goal to provide compensation for these losses by means that are mutually agreeable with resource managers. The construction of the Devil Canyon dam (RM 152) will prevent chinook salmon from migrating upstream of Devil Canyon. Chinook salmon have a high commercial, subsistence and sport value and are numerous in the Susitna River below Devil Canyon. However, upstream of Devil Canyon they are not abundant, as high velocities of the Devil Canyon rapids usually limit upstream migrations of fish . Because of their low densities upstream of Devil Canyon , losses of chinook salmon are not considered to be significant. Compensation for 47 lost chinook spawning habitat will be provided in one of two ways: (I) by mitigative flow releases for juvenile chinook salmon below Devil Canyon, or (2) by habitat improvements in the middle Susitna R i ver as part of the impoundment mitigation (See Section 6.3). The Stage I and 3 Watana impo·,mdments may reduce the recruitment to burbot populations inhabiting the reservoir area (Section 4.1.4 and 4 .3.4). However, burbot densities in the upper Susitna River are presently low and burbot are not highly sought by fishermen in this reach of the river. Therefore, no mitigative measures are planned for burbot, as any reduction in burbot populations in the impoundments is considered insignificant. 48 6.0 DEVELOPMENT OF MITIGATION PLAN 6 .1 HISTORY OF IMPOUNDMENT MITIGATION PLANNING The FERC license application (February 1983) for the two-stage, two-dam Susitna Project recognized that the loss of clearwater tributary habitat in the impoundment zones would be a significant project impact on Arctic grayling populations in the upper Susitna River (APA 1983b). The proposed mitigation included the following compensation to provide for lost grayling habitat in the impoundment zones: (I) fund research on the hatchery propagation of Arctic grayling, (2) expand or build a hatchery to propagate Arctic grayling, (3) stock Arctic grayling fingerling in suitable barren lakes within the project area, and (4) if Arctic grayling propagation proved to be technically infeasible, expand a rainbow trout hatchery and stock rainbow trout in the Devil Canyon reservoir. Stocking Arctic grayling in barren lakes within the project area was proposed as the primary means of compensation because of the desirability of in-kind, in-basin compensation. Resource agency comments on this proposed mitigation plan were generally unfavorable and concluded that hatchery propagation of Arctic grayling must be judged as speculative (ADF&G 1983c, USFWS 1983). The agencies suggested that mitigation measures should have documented successes in Alaska if possible and, if mitigation measures are unproven, a demonstration of their effectiveness in the project area should be undertaken. In the Fish Mitigation Plan (WCC 1984) options were evaluated that would mitigate impacts resulting from the project. The proposed mitigation for habitat losses in the impoundment zones was the expansion of a rainbow trout hatchery and the stocking of rainbow trout fingerling in out-of-basin lakes as the primary compensation. This was proposed because of the high probability for success. Hatchery propagation of rainbow trout in Alaska is a documented success and rainbow trout are highly sought by sport fishermen . The proposal of stocking Devil Canyon reservoir with rainbow trout was dropped, due t o concern expressed about the expected low productivity and relat ively high turbidity levels in the Devil Canyon reservoir. The propagation and stocking of Arctic grayling were also proposed as an option for achieving compensation, 49 because of the desirability of in-kind replacement and progress in the technology of rearing grayling in hatcheries. The ADF&G responded that rainbow trout hatcheries and stocking programs were already in place and that the department did not favor an expansion of this program as mitigation for lost habitat in the impoundments (ADF&G 1984). Instead, the ADF&G endorsed the acquisition of public access and the development of site facilities for recreational fishing in the Susitna River and its tributaries below Devil Canyon. The enhancement of middle Susitna River salmon stocks by habitat improvements was also favored. A summary of agency comments on impoundment mitigation is shown in Table 13 . As a result of agency comments on impoundment mitigation planning, this report evaluates three options for providing compensation for the expected losses of fish habitat in the impoundment zones: (I) acquiring public access to the Susitna River and its tributaries below Devil Canyon, (2) habitat modifications or improvements in the middle Susitna River that would enhance important resident species or important sport species of salmon, and (3) the expansion of an Arctic grayling hatchery, the hatchery propagation of grayling and the stocking of grayling within and out-of-basin areas. 6.2 ACQUISITION OF PUBLIC ACCESS 6.2.1 Background Increases in population and tourism in Alaska have resulted in a high demand for r e creational fishing. Recreational fishing is now considered an important factor in the total management of many of the state's fisheries (Mills 1984). In Southcentral Alaska, the high recreational use of fish resources in the region is largely attributable to the accessibility of many lakes and rivers by the road system, the close proximity of these areas to major population centers and healthy fish resources. The highest demand for recreational fishing is largely concentrated in areas that are accessible by road, which in some situations creates uneven use patterns of the resource and intensifies pressures on resource managers to provide additional recreational opportunities. so Table 13. Agency comments on Impoundment Mitigation Planning. Agency Date ADF&G 13 Jan 83 USFWS 14 Jar . 83 USFWS 18 Dec 84 ADF&G 31 Dec 84 Reason for Correspondence Review of Draft Exhibit E, FERC License Application Review of Draft Exhibit E, FERC License Application Comments on Fish Mitigation Workshop of 4 Dec 84 Comments on Fish Mitigation Workshop of 4 Dec 84 Source: ADF&G 1983c, 1984; USFWS 1983, 1984 . Comments Grayling propagation in experimental stages. Compensation by stocking grayling is speculative . Mitigation measures should have proven success in Alaska. Demonstration of hatchery-rearing of Arctic grayling needed. The APA appears to be planning impoundment mitigation with realistic objectives in accord with project mitigation policy. ADF&G does not support the expansion of the rainbow trout stocking program and does not favor stocking of the impoundment. ADF&G endorses the acquisition of public access and developing site facilities for recreational fishing in the Susitna River and its tributaries below Devil Canyon. Also favors habitat improve- ments for salmon in the middle Susitna River (Talkeetna-to-Devil Canyon). The State of Alaska, recognizing the need to rectify immediate recreational use problems and plan for future development and management of recreational areas, has developed a recreation action plan for Southcentral Alaska (ADNR a nd ADF&G 1984). This plan emphasizes the need for the designation of recreational areas, the acquisition of public access to currently utilized and future recreational areas, and the development of site facilities at recreational areas. The Susitna River basin is a large recreational area, which is close to populations in Anchorage and the Mat-Su Valley and contains abundant fish resources. However, access to the lower 75 miles of the Susitna River is limited to one privately owned boat launch at Kashwitna Landing and to some of the eastside tributaries along the Parks Highway. Thus, resource managers have identified the need to acquire public access and develop site facilities in the Susitna Basin to even out resource utilization and create new fishing opportunities (ADNR and ADF&G 1984). Five parcels of land in the Susitna Basin have been identified for acquisition in the recreation action plan (ADNR and ADF&G 1984). The five parcels are listed in the order of priority in Table 14. The first two priorities, Kashwitna Landing and Little Willow Creek, would increase the accessibility of the Susitna River. The others would improve access to lakes and tributaries in the basin, or provide hiking trails. The recreation action plan also recommends the development of three recreational facilities in the Susitna Basin. The three facilities development projects are listed in Table 14. All three developments would improve access to the Susitna River by building roads, trails, or boat launches. Resource managers have recommended that the Southcentral recreation action plan deserves timely implementation (ADNR and ADF&G 1984). However, it is recognized that the plan is an ambitious one that may take years to fully implement, particularly in view of the declining capital budget of the State of Alaska. Thus, the ADF&G (I 984) has endorsed land acquisition and facilities development for recreational fishing in the Susitna River as the preferred 52 U1 w Table 14. Land acquisitions and facilities development projects currently proposed by the state of Alaska in the susitna River Basin. Project Land Acquisitions Kashwitna Landing Little Willow Creek Neil Lake Moose Creek Description Boat launch on Lower Susitna R. Provide access from Parks Hwy. to Susitna R. Floatplane access to the Deshka R. Road access for river use Nancy Lakes Inholdings acquisition for trails Facilities Development Willow Creek State Recreational Area Major fishing area Talkeetna Boat Launch Campground/access/boat launch Sheep Creek Trail to fishing area near Parks Hwy. Source: ADNR and ADF&G 1984. Estimated Costs Capital Operating Costs Costs $ 500,000 $ 180,000 $ 600,000 $ 200,000 $ 250,000 $7,735,000 $ 173,000 $ 200,000 $212,500 measure of compensation for lost fish habitat and reductions in fish populations resulting from the impoundments of the proposed Susitna Hydroelectric Project. 6.2.2 Sjte Selection The selection of specific parcels of land and the development of recreational facilities will require close coordination between the APA and resource agencies. After the license to build the project has been granted, potential land acquisitions and facil i ties development projects within the Susitna Basin will be prioritized with input from resource managers. The Southcentral Alaska recreation action plan (ADNR and ADF&G 1984) and any forthcoming planning documents on this subject will serve as the basis for site selections. Factors that will likely be considered during the selection process include: 1. identification of potential. sites, 2. historic use levels of the sites, 3. benefits associated with land acquisitions or facilities developments, 4. cost appraisals of lands or developments, S. location of sites in the Susitna Basin, 6. timetable for acquisitions or developments, and 7. the probability of acquiring or developing sites by conventional funding sources. After land parcels or facilities developments have been selected, the APA will take the necessary steps to complete the acquisition of selected lands or the development of site facilities with the highest ranking. This will occur within a time frame mutually agreed to by the APA and the agencies. In the event that selected acquisitions or developments are found to be infeasible the APA, with concurrence of the agencies, will negotiate the acquisition or development of the next highest priority. 6.2.3 Q2ill In Exhibit E of the FERC license application, costs for expanding an existing hatchery to propagate Arctic grayling were developed (APA 1983b). Capital 54 costs were estimated to be $750,000 in 1982 dollars, while annual operating and maintenance costs were an estimated $110,000. It was proposed that $190,000 be spent to develop Arctic grayling propagation technology. Thus, a. total capital budget of $940,000 plus an operating budget of $110,000 per year, was proposed to provide compensation for lost grayling habitat in the impoundment zones. Since compensation for lost grayling habitat is of primary concern in impoundment mitigation planning, the costs developed in the license application can be used as a basis to budget for land acquisitions or recreational facilities development projects. 6.2.4 Monitoring Studies After the acquisition of lands or the development of recreational facilities is completed, it is assumed that resource agencies will manage and maintain the lands and facilities. Therefore, monitoring studies are not planned for these measures at this time. 6.3 HABITAT IMPROVEMENTS 6.3.1 Background The Alaska Department of Fish and Game (1984), in review comments on the Fish Mitigation Plan (WCC 1984), indicated that habitat improvements enhancing salmon stocks in the middle Susitna River (Talkeetna to Devil Canyon) should be considered as compensation for lost fish habitat in the impoun d ment zones. Since the lost habitat primarily affects important sport species in the upper Susitna Basin, mitigation planning has focused on the enhancement possibilities for important sport species of salmon in the middle Susitna River: chinook and coho. Additionally, habitat improvements enhancing important resident sport fish (rainbow trout and Arctic grayling) in the middle Susitna River are also considered. 6.3.2 Site Selection Most mitigation plann i ng and associated field data collection in the middle river have concentrated on mitigating for potential losses of chum salmon spawning ss habitat in sloughs and side channels. Because the downstream impacts of the three stage project have not yet been addressed, it is unknown if slough excavations and other mitigation measures proposed to rectify i mpacts resulting from the two stage project will still be appropriate. However, if slough excavations are needed to maintain chum salmon spawning habitat, additional modificat ions can be done to enhance coho rearing and possibly juvenile rainbow trout and Arctic grayling habitat. For example, in spawning channels constructed in the Chilkat River near Haines, Alaska, rip-rap added to the sloping sides of the channel to stabilize the banks also provided habitat for juvenile coho salmon (B. Bachen, NSERA, pers comm., 1985). When specific mitigation measures are proposed for downstream impacts, this type of habitat improvement can be incorporated. Other improvements are also under consideration in the middle Susitna River. In the 1985 field season, studies will examine the potential for removing fish passage barriers and the expected amount of habitat to be gained from such removals. Several sites to be examined and the potential benefits are listed below. I. Fourth of July Creek -expand rainbow trout and possibly coho salmon habitat. 2. Gash Creek -expand coho habitat. 3. Portage Creek lake systems -expand rainbow trout and Arctic grayling habitat. After field data are available, the feasibility of these habitat modifications and potential benefits can be assessed. Upland sloughs will also be examined for potential habitat improvements in the 1985 field season. Mitigation measures that will improve rearing and overwintering conditions for juvenile salmon and for resident species will be evaluated. Additionally, habitat improvements in the lower Susitna River basin may be 56 evaluated in the future, if improvements in the middle river are found to be unattractive. 6 .3.3 ~ The costs associated with placing rip-rap along both banks of a 1,000' long excavated slough or side channel in the middle river is shown in Table 15 . The costing assumes that the channel will be excavated under the downstream impacts mitigation budget and that equipment used during excavation will be used to haul and place the rip-rap. Railroad transportation to the slough or side channel is also assumed. The costs of rip-rapping a hypothetical slough or side channel are intended to give a relative magnitude estimate. They do not reprr ~ent a proposed budget for impoundment mitigation compensation. It is assumed that budgeting for habitat improvements in the middle river will be developed within the total budget set forth in the license application (APA 1983b) (Section 6.2 .3 of this report). After the 1985 field season, specific mitigation measures to improve habitat in the middle Susitna River will be proposed. Detailed budgets will be proposed with the associated habitat improvement. 6.3 .4 Monitoring Studies If habitat improvements are chosen in the middle Susitna River to provide compensation for lost fish habitat in the impoundment area, monitoring studies will be conducted to evaluate the success of the improvements. It is assumed that monitoring efforts required for habitat improvements will be coordinated with the monitoring for other mitigation measures in the middle Susitna River. The estimated costs of a 2 person crew making 4 one-week field trips to the site(s) to assess fish utilization and abundance and the preparation of a year-end summary report are shown in Table 16. The scope of work for monitoring studies and budget details will be refined when specific habitat improvements are proposed. 51 Table 15. costs associated with rip-rap placement alODl both banks of a 1,000' lODl excavated slc:u;h or side channel in the middle SUsitna Ri ver1 • Description Material2 $ 15' 500 Equipnent 3,000 labor 13' 500 ~ 3.000 Total $ 35,000 1 M::lbilization ani dem:lbilization costs have not been evaluated as equipment ani personnel are assumed to be oosite con:iucti.n:] sla.lgh m:xlifications for downstream inpacts. 2 Includes transportation of riprap to the site. 58 Table 16. Annual mcnitori.rq <XlSts far evaluat.in; habitat i.Jrprovements in the middle SUsitna River. Description Labor Transportation Equipnent J:Bta Analysis 59 $ 36,500 600 2,500 4.000 $ 43,600 6.4 HATCHERY PROPAGATION OF ARCTIC GRAYLING 6.4.1 Background Habitat alterations resulting from the impoundments will primarily affect Arctic grayling populations in the upper Susitna River. When possible, it is desirable to compensate anticipated reductions of fish populations with in-kind replacement (USFWS 1981 ). The hatchery propagation and stocking of Arctic grayling is an in-kind compensation measure. However, since Arctic grayling propagation technology is still in the developmental stages and cannot be fully relied on to provide compensation, the ADF&G (1984) has recommended other options to provide compensation for lost fish habitat in the impoundments. At present, the hatchery propagation and stocking of Arctic grayling is the least preferred of the three options evaluated in this report. 6.4.2 Hatchery Propagation Technology Arctic grayling artificial propagation is being conducted by the Fisheries Rehabilitation Enhancement and Development (FRED) Division of ADF&G at Clear, Alaska. Arctic grayling broodstock have not yet been developed at Clear Hatchery, so eggs are taken from wild fish and transported to the hatchery for incubation. In 1984, over 2.0 million eggs were taken from grayling in three lakes: Moose, Jack and Tahneeta (Parks et al. 1985). Using wild fish as an egg source is not a fail-safe method, but in the absence of an established hatchery-production brood stock program it is the best method available. Eggs are incubated at Clear H1tchery using Heath Techna ·stacks. Water temperatures are varied between 3.5 and 10.5°C to manipulate the emergence timing of fry. In 1984, egg-to-fry survival was over 70 percent (Parks et al. 1985). Grayling are usually stocked as sac-fry. However, because the stocking success of planting sac-fry is generally low, efforts are underway to develop 60 fingerling production at Clear Hatchery (Parks et al. 1985). In 1984, about 125,000 grayling were reared to fingerling size (2.0 gram weight). The average survival rate of 560,000 sac-fry to the fingerling stage using nine different diets was approximately 22 percent. Fish raised on diets of krill, liver, and OMP mash exceeded the average survival rate. Survival rates were 72 percent with the krill diet, 66 percent with the liver diet and 52 percent with Omp mash diet. Fish raised on the other six diets had survival rates of 30 percent or less (Parks et al. 1985). Although fingerling production is still in the developmental stages, the results of experimental efforts in 1984 indicate large-scale fingerling production of Arctic grayling is feasible. 6.4.3 Stocking Program Sjte Selection If a grayling stocking program is found to be feasible and is selected as a mitigation measure, stocking sites will be selected in close consultation with resource managers. Sites will be evaluated within the Susitna Basin and outside the Susitna Basin. The potential sites for stocking grayling within the project area appear to be limited. Most lakes and streams in the upper Susitna Basin contain unexploited fish populations that are currently utilizing most of the available fish habitat, as indicated by the high densities of fish (ADF&G 198la, 1983a, Sautner and Stratton 1984). Barren lakes or streams with barriers to fish movements could be stocked. However, these sites will need to be evaluated for their capacity to successfully overwinter fish and their accessibility to anglers. It may be possible to plant grayling in borrow pits resulting from th e construction of the project access roads and dams. However, unless the proposed side-borrow technique for building access roads is inadequate, no gravel pits will be excavated during access road construction. The major gravel pit used during construction of the Watana dam at Borrow Site E will be rehabilitated and connected to the Susitna River, allowing fish utilization of this area without the need for stocking (Bradley et al. 1985). Most of the other 61 borrow sites used during construction will be inundated by the impoundments (APA 1983a,b). Therefore, the possibility of stocking borrow sites with grayling will depend on the siting of pits and requirements of gravel fill for the three stage project. Stocking grayling in out-of -basin areas could supplement existing stocking programs or create new fishing opportunities. Site selection will need to be done in close consultation with the Sport Fish Division of ADF&G. In 1984, 65 sites throughout Alaska were stocked with grayling (Parks et al. 1985). Thus, an active stocking program of Arctic grayling exists, when fry and fingerling are available from the hatchery. 6. 4.4 C2.ill The costs associated with implementing a grayling stocking program were developed in the FERC license application. The cost of expanding an existing hatchery facility is approximately $750,000 in 1982 dollars, while the operating and maintenance costs are an estimated $110,000 per year (APA 1983b). 6.4.5 Monitoring Studies Monitoring the success of a stocking program is an integral part of this mitigation option. The costs for monitoring are assumed to be similar to the monitoring budget proposed for habitat improvements (Table 16). The actual scope and budget of a monitoring program will be developed if this option is selected and when specific stocking sites are chosen. 62 7. 0 LI'I'ERA1URE CITED Alaska Department of Fish an:i Game. 198la. SUsitna Hydro Aquatic Studies - Rlase I Report: Resident Fish Investigatic:-.s on the upper SUsitna River. Prepared for Acres American, Inc. B.lffalo, NY. 137 pp. Alaska Department of Fish an:i Game. 198lb. SUsitna Hydro Aquatic studies - Rlase I Final Draft Report: Adult anadralnls fisheries project. Prepared for Acres American, Inc. lllffalo, NY. Alaska Department of Fish and Game. 198lc. SUsitna Hydro Aquatic studies - Blase I Final Draft Report: JUvenile anadratoJs fish study on the lower SUsi tna River. Prepared for Acres American, Inc. B.lffalo, NY. 121 :pp. Alaska Department of Fish an:i Game. 1982a. statement of Policy on Mitigation of Fish an:i Game Habitat DisruptialS. J\Ineau. Alaska Department of Fish an:i Game . l982b. 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Presented to Governor Bill Sheffield. Alaska Power Authority. 1982. SUSitna Hydroelectric Project: Fish an:i Wildlife Mitigation Policy. Alaska Power Authority. Anchorage, AK. Alaska Power Authority. 1983a. Application for license for major project, susitna Hydroelectric Project, before the Federal Energy Regulatory C)'mni ssion. Vol. SA. Exh:i]:)it E, Claps. 1 an:i 2. Alaska Power Authority. 1983b. Applicatioo for license for major project, SUSitna Hydroelectric Project, before the Federal Energy Regulatory Qmnission. Vol. 6A. Exh:i]:)it E, Chap. 3. Alaska Power Authority. 1985. Board of Directors Meeti.n;. ~lemental Information on Li.censin;J Review an:i Consideration of Prc::p::>sed stagin:;J of Construction of the SUSitna Hydroelectric Project. l'ay 3. Arctic Envi.ranmental. Informatioo arxl r::.ata Center. 1985. susitna River Ice Processes: Natural a:n:lltioos an:i Projected Effects of Hydroelectric Develc:pnent. Volume 1. Draft. Bachen, B.A. 1985. Personal cammmication. NSERA. 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In Report No. 4: Iv:::t::ess ani Transmission corridor Investigations (JUly -oct:ober 1983), by D. Schmidt, C. Estes, D. crawford ani D. Vinoent-Lan], Eds. Alaska Deparbnent of Fish ani Game. Arx::horage, AK. 65 Sclnnidt, D., and M. Stratton. 1984. C'lapter 2: Pop.llation dynamics of Arctic graylin:J in the lJWer SUSitna Basin. In Report No. 4: Acx::ess and Transmission corridor Investigations (July-october 1983), by D. Sclnnidt, c. Estes, D. crawford and D. Virrent.-I..all;, eds. Alaska Deparbnent of Fish and Game. Anchorage, AK. Sclnnidt, D., S. Hale, D. crawford, and P. SUchanek, eds. 1984. Report No. 2: Resident and Juvenile Arladra1ols Fish Investigations (May -Oc::tabel: 1983). Alaska Deparbnent of Fish and Game. Anchorage, AK. Umeda, K., K. Matsumura, G. Okukawa, R. Sazawa, H. Hornna, M. Arauchi, K. Kasahara, and K. Nara. 1981. Cdlo Sal.nal (Oncorhynd'rus kisutch) Transplanted fran North America into the Idlani River, Eastern Hokkaido. Japan. Scientific Report, Hokkaido Sal.nal Hatchery. 35. u.s. Fish and Wildlife Service. 1981. Endan:]ere::i and 'Ibreatened Wildlife ani Plants. Federal Register 50 CFR 17.11 and 17.12. January 1, 1982. u.s. Fish and Wildlife Service. 1983. Review c:amnents -Draft Exh..ibit E ·· susitna Hydroelectric Project. Prepared for Alaska Power Authority. U.S. Fish and Wildlife Service. 1984. Letter fran Rebert Bowker to J.S. Ferguson of APA. o:mnents a1 SUSitna Hydroelectric Project -Fish Mitigation Plan and Worksl'lq). l)ecpmhp.r 18. Woodward-clyde Consultants. 1984. Fish Mitigation Plan. SUSitna Hydroelectric Project. Prepared for Alaska Power Authority. 66