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Home My WebLink AboutMahoney Lake Hydroelectric Project Final Consulation Document 1994August 8, 1994 Mr. Riley Snell Alaska Industrial Development Agency 480 W. Tudor - Anchorage, AK 99503 | D Vie m Subject: Mahoney Lake Hydroelectric Project [i : FERC Project No. 11393 BUG - Final Consultation Document Alaska Dear Mr. Snell: enc ¢ Enclosed is a copy of the Final Consultation Document (FCD) for the Mahoney Lake Hydroelectric Project. The FCD is based on the Initial Consultation Document that was distributed via letter on March 16, 1994, incorporates the comments received during Stage I consultations, and contains copies of all consultation correspondence and responses developed in reply to concerns addressed in agency comment letters and at public meetings. Issuance of the FCD concludes Stage I of the FERC licensing process and finalizes our agreements on what studies will be performed during Stage II. Thank you for your participation to date. In addition to conducting the studies and developing the overall license application during Stage II, please be advised that the Applicant intends to initiate NEPA compliance for this application during this pre- filing stage as well. Consistent with the authority granted under Section 2403(b) of the Energy Policy Act of 1992, the Applicant will prepare an Environmental Assessment for the Project and will file that as part of its license application in lieu of preparation of Exhibit E, the environmental exhibit traditionally prepared as part of a license application. A scoping process will be conducted and a draft Environmental Assessment will be made available for comment and review prior to its submission to FERC. This process will be conducted by the Applicant in close coordination with FERC staff. In the near future, we will advise you of further details on this process and the opportunities for your participation. We believe this process will provide an efficient way for all interested parties to participate in the environmental review of the proposed Project and look forward to your active involvement. Please contact me if you have any questions regarding the licensing process for the Mahoney Lake Hydroelectric Project. Sincerely, HDR ENGINEERING, INC. Michael V. Stimac Manager, Licensing & Environmental Services HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 500. 108th AvenueNE, Suite 1200 "Bellevue eo 980045538, ve ee a ee ee Final Consultation Document City of Saxman, Alaska Mahoney Lake Hydroelectric Project FERC Project No. 11393-000 Final Consultation Document TABLE OF CONTENTS ection Page 120 Mee introductionerr-fr ier it inne ken in holt ine nn een enon snes 1 2.0 General’Engineering Design” jo. 10 12 oo le) tele Se) 1) ies 3 3:0 men Operational ;Mode x-p-w-w-w-m-1-m WS -E-WOW-N--E-W- WEN WNW MeN 7 Wowo wo“ 14 4.0 Environmental and Regulatory Issues ... 2... 2... ee eee eee eee eee 17 Environmental |[ssues) (iyo eit oi oie etre cio site) ooo cutee oes oe ool 17 VOC asa 7g CCT aera ur FG EG GIEERICIIC ORGING IGN ICTIORGNG IG GUD NCIGNOEG ilo GUN EONICIOND 23 5.0 Stream Flow and Water Regime ...... 2.0... cece eee eee eee 25 (Cnr G DOO CO COO OOD DOOD CO DOC UO CUO DOCU CUO UO OOD OOO GOS 25 Derivation of Long Term Daily Flow Database ............-2-22-2--65 25 Flood: rrequency7Atalysissse eee ee ene ee eee 28 CHP IYO AYN oop OOOO DOO OC OOOO OCCOCCCOOCCOODDCOOOCOC 29 1.0) Licensing | Stady Plans Worcs oe eo eee cle) eclein cl crease tieracls 30 Water Quality and Quantity... 2... ee ees 30 Fisheries and Aquatic’ Resources (7 «6.1 +) 1% oh oe) ios ©) Vee 0) 51 lle 33 Wildlife'and Botanical"Resources ey. .nor nn note enon nein eee enemies 34 Historic and Archeological Resources... 6.0.2... 0c ee eee eee eee eee 36 Recreational, REGOUTCES fers -5-1 -a-a-h sak aon k be 8 8 RRMA CANORA ROR RARER 37 AORTIC REGOUTCOR I rer delice ciel irra ann nomena Ender ea ones 38 Erosion and Sediment Control Plan ...............22 e+e ee ee eeee 39 8:0 me Bibliography Merewsreete ree ee eee cee tee ee ce ee enn em ates senenetenceme tans 42 9.0 Consultation Document Mailing List ... 2.0... 2... cee eee eee eee 43 Mahoney Lake Hydroelectric Project August 1994 i FERC No. 11393 Final Consultation Document TABLE OF CONTENTS (Continued) LIST OF FIGURES 1-1 Project Location Map .............200022 2200 2-1 ~~ Project Site, Plan and Profile ..................4- 2-2 Upper Tunnel and Lake Tap .............-2--20-- 2-3 Shaft and Tunnel Sections ...................-.6.4. 2-4 Powerhouse, Plan and Section ................-... 2-5 Powerhouse Site Plan .................220000. 2-6 Access Road and Transmission Line ............... 5-1 Flow Duration Curve...........-.....-.220008- Table 2-1 ‘Principle Project Features ................-02000- 3-1 Average Annual Energy Generation - Year 2000 ........ 3-2 Average Annual Energy Generation - Year 2005 and Beyond 5-1 Upper Mahoney Lake, Average Monthly Flow ......... APPENDICES Alternative Project Configuration Discussion 1982 U.S. Fish and Wildlife Service Coordination Act Report Agency Correspondence Temperature Information Geotechnical Information Hydrology Information Response to Comments QMO Aw > Mahoney Lake Hydroelectric Project August 1994 ii FERC No. 11393 ADFG ADGC ADNR Beck CFR CFS COE DEIS ESCP FERC KPU NMFS NPS PDEIS PURPA SHPO USFS USFWS USGS August 1994 LIST OF ACRONYMS Alaska Department of Fish and Game Alaska Division of Governmental Coordination Alaska Department of Natural Resources R.W. Beck and Associates Code of Federal Regulations Cubic Feet Per Second U.S. Army Corps of Engineers Draft Environmental Impact Statement Erosion and Sediment Control Plan Federal Energy Regulatory Commission Ketchikan Public Utilities National Marine Fisheries Service National Park Service Preliminary Draft Environmental Impact Statement Public Utility Regulatory Policies Act State Historic Preservation Officer U.S. Forest Service U.S. Fish and Wildlife Service U.S. Geological Survey Final Consultation Document Mahoney Lake Hydroelectric Project FERC No. 11393 Final Consultation Document 1.0 INTRODUCTION The City of Saxman, Alaska, is investigating the development of a 9.6 megawatt (MW) hydroelectric generating plant located at Mahoney Lake near Ketchikan, Alaska. Cape Fox Corporation, an Alaskan corporation established under the Alaska Native Claims Settlement Act as the village corporation for the Native village of Saxman, has been retained by the City of Saxman as the development agent for the Project. The proposed Mahoney Lake Hydroelectric Project is located five miles northeast of Ketchikan, Alaska and about four miles north of an existing project, Lake Silvis/Beaver Falls Hydroelectric Project, which is owned and operated by the City of Ketchikan d/b/a Ketchikan Public Utilities (KPU). The Mahoney Lake Hydroelectric Project location is shown on Figure 1-1 and is located on lands owned by the Cape Fox Corporation and the U.S. Forest Service (USFS). Hydroelectric development at Mahoney Lake has been studied since the 1970’s. A considerable amount of data has been gathered in the Project area on water quantity and quality, fisheries and geology, and an environmental impact statement was prepared for a project at this site in 1983. The Project presently proposed has been revised from previous alternatives studied to reduce environmental impacts and to make it more cost effective. The Federal Energy Regulatory Commission (FERC) issued a Preliminary Permit (No. 11393-000) to the City of Saxman in June 1993 to allow them to study the Project. This permit expires in June 1996. The FERC regulations require the Applicant to follow a three-stage agency consultation process in the preparation of a hydropower license application for the Project. The Applicant must contact all appropriate federal/state/local agencies, Native Americans, and public citizens who are interested in the Project. The reason for this is to obtain input on concerns about the proposed Project, to identify environmental or other issues surrounding the Project development, and to provide clear communication about the proposal and its possible impacts to all interested parties. The Initial Consultation Document (ICD) was distributed on March 16, 1994, to interested agencies to provide a general overview of the proposed Project design, operation, and potential impacts. Following distribution of the ICD, two agency/Native American/public meetings were held in Ketchikan on April 26, 1994, to discuss the proposed Project and potential environmental impacts, and identify data to be obtained and studies to be conducted as part of the FERC consultation process. Written comments were due within 60 days following the joint meetings or by June 25, 1994. Comments received on the ICD have been incorporated into this document. Issuance of this Final Consultation Document (FCD) concludes Stage I of the FERC consultation process. The FCD outlines the studies that will be performed during Stage II and contains copies of all consultation correspondence and responses that were developed in reply to concerns addressed in agency comment letters. This three-stage consultation process will lead to the submittal to the FERC of a license application for a Major Unconstructed Project (18 CFR 4.41) that will be developed utilizing the results of the agreed-to studies. Mahoney Lake Hydroelectric Project August 1994 1 FERC No. 11393 XREF/S: ML-1B DATE PLOTTED: 7/22/94 SCALE: 1 = 1 FILENAME: M: \MAHONEY\100659HA.DWG ARCTIC OCEAN PACIFIC OCEAN LOCATION MAP CITY OF SAXMAN, ALASKA APPLICATION FOR LICENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 PROJECT LOCATION AND VICINITY MAPS FIGURE 1-1 HDR _ Engineering, Inc. Final Consultation Document 2.0 GENERAL ENGINEERING DESIGN Several detailed environmental studies have been conducted at Mahoney Lake previously by the U.S. Army Corps of Engineers (COE) and R.W. Beck and Associates (Beck) on behalf of KPU. Because of southeast Alaska’s dependency on diesel fuel for electrical generation and impacts caused by the oil crisis during the mid-1970’s, Congress directed the COE to conduct feasibility studies of hydropower sites to serve Ketchikan, as well as other areas of southeast Alaska. An Appraisal Report for KPU was prepared by Beck in June 1977 for the Swan Lake, Lake Grace, and Mahoney Lake Hydroelectric Projects. A Preliminary Interim Feasibility Report on Hydroelectric Power and Related Purposes for Ketchikan Area, Alaska and a Preliminary Draft Environmental Impact Statement (PDEIS) for the Proposed Mahoney Lakes Hydropower Project was prepared by the COE in 1978. More studies were conducted and another version of these documents were compiled and distributed in July 1983 as a Draft Interim Feasibility Report and Environmental Impact Statement; Hydroelectric Power for Sitka, Petersburg/Wrangell, and Ketchikan, Alaska (DEIS). These previous studies were reviewed in detail. A site visit in June 1993 was conducted to review present conditions and identify potential development sites as well as potential problems. The Project area was surveyed to develop accurate and detailed maps. A feasibility study was then performed to review alternative Project arrangements, select the best development alternative, and to estimate energy production and development cost for the proposed Project. The proposed Project will use a “lake tap", which will tunnel into Upper Mahoney Lake about 75 feet below its surface and then use a series of tunnels to convey water from Upper Mahoney Lake to the powerhouse located near Lower Mahoney Lake at the base of a large waterfall (Figure 2-1). No dam will be constructed. The normal water surface elevation of Upper Mahoney Lake is El. 1959. The centerline of the turbine runner in the powerhouse will be set at El. 150, thereby, providing a gross head differential of 1,809 feet. As shown on Figure 2-1, a 3,350-foot long, 8-foot high by 8-foot wide horseshoe-shaped tunnel will be constructed from the powerhouse into the hillside. Portions of the tunnel will be lined with shotcrete, and supported by rock bolts and steel sets as required. The tunnel will provide permanent access to a 32-inch diameter welded steel pipe supported on concrete saddles within the tunnel. The tunnel invert will slope at a 10% grade to the powerhouse. Mahoney Lake Hydroelectric Project August 1994 3 FERC No. 11393 AREE / 3: ML— 1D/ML=PNUF /ML-DADEL oun 5 2 z o z 5 a 1000 B UPPER MAHONEY LAKE W.S.EL. 1959.0 LAKE TAP UPPER MAHONEY LAKE NORMAL W.S.EL 1959.0 ELEVATION, FEET CITY OF SAXMAN, ALASKA APPLICATION FOR UCENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 PROJECT SITE PLAN AND PROFILE FIGURE 2-1 HDR Engineering, Inc. Final Consultation Document At the upstream end of the 8-foot tunnel, a 1,370-foot long rock-lined vertical shaft will be constructed, as shown on Figures 2-1 and 2-3, that will reach the ground surface in a flat area about 1,500 feet downstream of the upper lake. Following excavation of the vertical shaft, construction will proceed on the "upper" tunnel and lake tap. Plan and section views of the tunnel and lake tap are shown on Figure 2-2. The upper tunnel will be an 8-foot horseshoe- shaped tunnel, about 1,480 feet in length. Tunnel walls will be left unlined except in areas requiring additional support. Maximum velocity at full turbine flow will be 1.4 feet per second (fps) through the tunnel, which is well below accepted standards for safe velocities in unlined tunnels. The upstream end of the tunnel will pierce the submerged rock walls of Upper Mahoney Lake at a depth of about 75 feet. A lake tap deeper than this level would provide more drawdown capability, but hydrologic analysis shows that further drawdown may not allow the lake to be re-filled completely each year. Preliminary surface investigations indicate the general rock quality in the vicinity to be competent for lake tap construction and tunneling. A concrete plug will be constructed at the downstream end of the lake tap pressure tunnel. A 4-foot diameter pipe will be installed in the plug to convey water from the upper tunnel to the vertical shaft. A valve house will be constructed immediately downstream of the plug, containing two butterfly valves and a vent pipe. One valve will act as the primary intake shut- off valve and the other as an emergency shut-off. Both valves will be motor-operated and connected by power and communication lines to the powerhouse. The powerhouse will be a semi-underground structure constructed at the portal entrance to the lower tunnel. A conventional above-ground structure was considered, but such a structure would be more subject to damage from avalanche. A semi-underground structure will be protected from an avalanche, and will not require extra equipment or make construction more complex since a tunnel portal needs to be constructed regardless of the type of powerhouse. The powerhouse will be essentially an over-excavated tunnel portal. Additional benefits of a semi- underground powerhouse are that it will reduce the amount of concrete required, and heating requirements will be less than in an above-ground structure. The powerhouse will contain a single twin-jet horizontal Pelton turbine. Maximum rated discharge will be 78 cfs and rated net head will be 1,730 feet. The synchronous generator will generate at 13,200 volts and be rated 9,600 kW continuous. Centerline of the turbine shaft will be at El. 150. The general layout of the turbine, generator, and auxiliary equipment is shown on Figure 2-4. An overall site plan of the powerhouse is shown on Figure 2-5. The powerhouse site has been carefully selected to avoid potential impacts to fish using Lower Mahoney Creek. The cascades and waterfalls between the upper and lower lakes end at a deep pool surrounded by bedrock walls at approximate elevation 140 about 800 feet upstream of Lower Mahoney Lake. Fish cannot pass this point on Mahoney Creek due to the waterfalls. The water discharged from the proposed turbine will re-enter Mahoney Creek at this pool. Mahoney Lake Hydroelectric Project August 1994 5 FERC No. 11393 XREF /S: ML- TB SCALE: 1 = 1 vn eouricy. NORMAL MINIMUM W.S.EL_ 1890.0 Z " MAHONEY — LAKE UPPER TUNNEL we 8 HORSESHOE TEMPORARY STEEL PLATE- SECONDARY ROCK TRAP: Va PRIMARY ROCK TRAP TUNNEL SECTION SCALE: 1” = 20-0" WATER SURFACE EL 1959 APPROXIMATE LAKE TAP LOCATION 100 PLAN SCALE: 1” = 100-0 ° 100 SCALE IN FEE NENT TO EL. 1970.0 INSTREAM FLOW RELEASE PIPE (ROUTE TO STREAM IF REQUIRED) 200 300 48°” EMERGENCY VALVE 48° INTAKE VALVE S’ x 7° PARTIALLY LINED SHAFT CITY OF SAXMAN, ALASKA APPLICATION FOR UCENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 UPPER TUNNEL AND LAKE TAP FIGURE 2-2 HOR Engineering. inc. EL. 510.0 ROCK TRAP — SHAFT/TUNNEL SECTION TYPICAL _UNLINED SHAFT SECTION SCALE: #~ = T-0 TYPICAL LINED SHAFT SECTION (AS REQUIRED, SCALE: #" = 1-0 SCALE: 4%" = 1-0 =) 8-0 TYPICAL SUPPORTED TUNNEL SECTION SCALE: 4" = 1-0 TYPICAL UNSUPPORTED TUNNEL SECTION SCALE: B= 1-0 CITY OF SAXMAN, ALASKA APPLICATION FOR LICENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 SHAFT AND TUNNEL SECTIONS FIGURE 2-3 HDR _ Engineering, Inc. XKeF /9: ML IB DeALED = I RIG FLUNIEU. 117 ¥0/ 99 a 36'-0" al. 6-0"! | T 7 N x ‘ 7 \ / \ / = \ / 14 x 15H \ | /ROLL-UP DOOR \ z | | > | . PERSONNEL DOOR | | 2 | | > | | | N | | \ | | ! | ee | i Lt 4 be 427-0" a ELEVATION SCALE: %~ = 1-0" \ \ BURIED S’ WIDE _TAILRACE CHANNEL (ROUTE TO STREAM) — 14'W x 15H ROLL-UP DOOR 5S TON HOIST 9.6 MW PELTON TURBINE EQUIPMENT LEGEND SURGE EQUIPMENT, CABLE TO SMTCHYARD (14) RELAY PANEL }QPQO@OOOOCDO QGOOOE CONCRETE PORTAL EXCAVATION LINE crs VOLTAGE REGULATOR /EXCITER NEUTRAL GROUND STATION SERVICE PANEL AC PANEL DC PANEL ORY TYPE TRANSFORMER BATTERY BATTERY CHARGER MOTOR STARTER HYDRAULIC PRESSURE UNIT ACCUMULATOR TANK @) CONTROL PANEL ELECTRIC UNIT HEATER ‘SUMP PUMPS @® esx @ rue @) Bookcase @) VENTLATIN LouvER @B) OL /WATER SEPARATOR CITY OF SAXMAN, ALASKA APPLICATION FOR LICENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 POWERHOUSE PLAN AND SECTION FIGURE 2-4 HDR Engineering, Inc. EL. 147 XREF/S: ML-TB. SCALE: 1 = 1 DATE PLOTTED: FILENAME: M;'\MAHONE Y\113659H.OWG ACCESS ROAD 13.2 KV UNDERGROUND TRANSMISSION LINE CITY OF SAXMAN, ALASKA APPLICATION FOR LICENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 POWERHOUSE SITE PLAN FIGURE 2-5 HDR _ Engineering, Inc. Final Consultation Document The transmission line route will begin at the powerhouse and follow along the south and east sides of Mahoney Lake, then run northerly to its interconnection point with the 115 kV Swan Lake transmission line near the confluence of the White River with George Inlet. A switchyard will be located approximately 0.8 miles from the powerhouse in a low avalanche hazard area. A power transformer will be located in the switchyard to step up generation voltage from 13.2 kV to the transmission voltage of 115 kV. The transmission line will include approximately 0.8 miles of 13.2 kV underground cable and 5.2 miles of 115 kV overhead construction. The Cape Fox Corporation has recently constructed a logging access road approximately 4 miles long from the intertie point near the White River south towards the project area. Approximately 2 miles of new road will be required to access the powerhouse site. This is the same route the transmission line will follow. The overhead transmission lines will be designed to protect raptors from possible electrocution by providing hunting perches and/or by use of approved raptor-proof designs. The access road and transmission line route are shown on Figure 2-6. Details of the proposed Project are summarized in Table 2-1. A discussion of alternative Project configurations that were considered is included in Appendix A. An alternative transmission line route that connects power output to the KPU system near their existing Beaver Falls Project is feasible from an engineering standpoint, but is more costly. This route could be considered if benefits to KPU exceed the additional cost of this alternative. Mahoney Lake Hydroelectric Project August 1994 . 10 FERC No. 11393 XREF/S: ML-TB DATE PLOTTED: 7/22/94 SCALE: 1 = 1 FILENAME; H; \MAHONEY\107659H.DWG EXISTING ACCESS ROAD REVILLAGIGEDO ISLAND CITY OF SAXMAN, ALASKA APPLICATION FOR LICENSE MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 "ACCESS ROAD/ TRANSMISSION LINE ROUTE FIGURE 2-6 HDR Engineering, inc. Final Consultation Document TABLE 2-1 MAHONEY LAKE HYDROELECTRIC PROJECT PRINCIPAL PROJECT FEATURES Number of Generating (Units 54) 5/5 cin of) io eo ies ole tle) ei ereliol ot ollienieyiol ote oilourel 1 Turbine ype cys teller eye odode) ails elle s)pottey eltonistcstsirclheyi atic letrallen stair lion solienalioe felons Pelton Rated Generator Output Mw crelsicleneie ene ieierolien eleielciicnonclonsielcrsonete ieieis 9.6 Maximum Rated Turbine Discharge, cfs... 2... 0... cee eee ee ee eee 78 Minimum)Rated| Turbine Discharpescfs) oocytes) ole tolled nee) ile syreileitel ole oot alte ie) = 8 Turbine Runner Centerline Elevation, fmsl .............- +e cece cece eens 150 Average Annual) Energy) ‘kW ini |l/oi14)-1/< 41/0) 10) elo) stro eyelet clones) et ef chen et elle el 41,740,000 Normal Maximum Reservoir Elevation, fmsl ..............-.--0-2e ees 1959 Normal Minimum Reservoir Elevation, fmsl ............. 20 ee eee eee eee 1890 (Gross|Head feet elicits te cy cite) celts, 4h ote, colley oy eit lta) oteas level ey ra) eal) le a Pollen oll oye Collet alco 1809 Net Head at Maximum Rated Discharge, feet .......... 0. eee eee erence 1730 Upper Mahoney Lake Drainage? Areas Sc 3) 105 |x) ayo fs) sil) eee oite of silat oll ici ot clio) al ellie toyed ls) ello) 2.0 Surface Area at Fl 959Sacresiea rer iewsncinsichenelionnicionelenenolenclen nel cielo Te Active Storage Volume at El. 1959, acre-ft ........... 00 eee eeeee 3,760 Average Annual Natural Outflow, acre-ft .............0202000ee 32,600 Average Annual Natural Outflow, cfs... 2... 0... cee ee ee eee 44.4 Diversion ype re iecel eens erence eee etd caciedl dicttese elel el ec sitonele Lake Tap at El. 1880 Upper Pressure Tunnel IESG fac) ole rellstolts ley ale tel sites Glo: 1 ifs) sila) isso) ell. 91 fs call to Partially Unlined Horseshoe Siz0) evel et evreyer oiled oiieacratlstclich el crroctleienedcrelion steered onsroleicleoiols 8-foot by 8-foot ength: | feet) tere yeclency al relencotecteltocrauciee steed ese slel sy ereircll sree ols 1480 Invest) Slope, | ft/ F855 ie 8 ash its 4 wile: otis ee] ilar lls, 4m ferns cl silt lls) wos eller «co's 0.002 Velocity at Maximum Turbine Discharge, fps ..............-.+2-000- 1.4 Pressure Shaft PLYDO} ey cite telfoiraisiis) cleats sale) eilsisuaiieieliliclitrmelien sh elie elton Partially Lined Rectangular SIZE) Hehe os sales et ces oltesetcertestelic ot eP¥e) elles cleedloy coffer sh este edlor ey cites clerrd colt 5-foot by 7-foot Top of Shaft) Hlevation;, fmsl||5 4) 5). l= 4 =) ele +) «/s aot aie ois) 5 oils of/s) + s/s) otis 1850 Bottom: of Shaft) Hlevation; final 5/5 <5 4-1/4) lero) oe oie ele clio) 4 elec) oe fel elie 480 Velocity at Maximum Turbine Discharge, fps...............000000 Dee) Lower Access Tunnel PRY De yeaienoncd cncieanelime isa sell omen Neon ellie otomelleMolienet Partially Lined Horseshoe SIZE: |e aids sol oraey coil efeed toh cede ceffcreey iol f ey cto) of sip oaolfey ch olen Hosts tsiral stesuce stolen (aired ots 8-foot eng feet Weis reils collec etp= rlteiret ooyor ote t cols colkey oy rote Mee) te) cate ralletse reyion al oss fa) 3,350 Invert Slope; | f/f cl als alls, 4 fer lle sures: 4 whe: ee am eler oles Ae erally clic 0.10 Mahoney Lake Hydroelectric Project August 1994 12 FERC No. 11393 Final Consultation Document TABLE 2-1 MAHONEY LAKE HYDROELECTRIC PROJECT PRINCIPAL PROJECT FEATURES (continued) Lower Access Tunnel (cont’d) Pipeline Type .. 0.0... ccc eee ce cee ewe eee Welded Steel on Saddles Pipeline Diameter, inches ... 2... 1... 2. eee ee ee eee 32 Pipeline Length: feet |ac.qs (sce aes aaa so ose alle ml ele sole woe 3350 Velocity in Pipe at Maximum Turbine Discharge, fps ............--00- 14 Powerhouse CE YPC econo lecelce cece el eel eae allo a no gw are fate ore elo eee Semi-underground Approximate Dimensions ............... 40-foot by 40-foot by 28-feet high Generator Floor Elevation, fmsl ..... 2.2.2.2... 2.2... ee eee eee eens 147 Tailrace Se eet a teed de cea tleriaio beetles acetals Buried Concrete Rectangular Length, feet ot eke cle eae ols elt tele e los ole alle le “ale los mle ol alle he 200 . Transmission Line Length of Underground Construction, miles .............. 0002 ee eee 0.8 Underground. Line Voltage, KV... . 0c es TTT Te 13.2 Length of Overhead Construction, miles ....... 2.0.2... eee eee eee 5.2 Overhead Line Voltage, kV... 2... ee ee ees 115 New Powerhouse Access Road DEY 2-2 wets se dlatcslas_1s.-ollecae- orbs o-tel orton Single-lane gravel surfacing with turnouts Dan t Mi 5 INNS sea ope te eee eee ene ooo se aa ste 2.0 Mahoney Lake Hydroelectric Project August 1994 13 FERC No. 11393 Final Consultation Document 3.0 OPERATIONAL MODE The proposed Project consists of a "lake tap" on Upper Mahoney Lake at a depth of about 75 feet below the existing natural lake level. The lake tap provides the capability to drawdown any available water in the upper portion of the lake regardless of inflow but without the necessity of constructing a dam. Diverted water would be conveyed through a 1,480-foot long upper tunnel where it would then drop 1,370 feet through the vertical shaft, then flow an additional 3,350 feet in a 32-inch diameter steel pipe to the powerhouse. Total drop in elevation is 1,809 feet. The powerhouse would contain a single Pelton turbine/generator unit capable of generating 9,600 kW of power and 41,740,000 kWh of energy in an average water year. The Project would intertie with the existing Swan Lake transmission line to provide additional energy and capacity to the KPU transmission and distribution system. The proposed Project will provide 9,600 kW of firm capacity to the KPU system assuming the Upper Lake has some storage available. The Project could operate continuously at full capacity for about 55 days assuming the full pool is drafted and the average inflow of 44 cfs came into the reservoir. Assuming 5 cfs of inflow, and starting with a full pool, the Project could operate continuously at full capacity for about 26 continuous days. Current total generation capacity of all resources available to KPU, including diesel units, is approximately 49,450 kW. The Mahoney Lake Project will operate at a 0.48 plant factor, _ typical for a storage Project. For comparison, the Swan Lake Project operates at a 0.42 plant factor and the combined KPU-owned hydroelectric projects operate at 0.63 plant factor. A computer-based model was set up to simulate operation of the Project, using average monthly inflows, an area-capacity relationship developed by the U.S. Army Corps of Engineers, and projected seasonal energy demands in the KPU system. Table 3-1 shows projected energy demand in the Ketchikan area based on several different forecasts. If the Project comes on-line in 1999 as planned, it should be possible to utilize all Project energy production in the first year of operation. By the year 2005, if even the conservative forecasts prove accurate, all Project output will be needed in the area. Table 3-2 shows the output from the Mahoney Lake operation model for a typical year after 2005. Mahoney Lake Hydroelectric Project August 1994 14 FERC No. 11393 Table 3-1 _p:\hyd\mahoney\tab3—1.wk3 CITY OF SAXMAN, ALASKA MAHONEY LAKE HYDROELECTRIC PROJECT Average Annual Energy Generation — Year 2000 Lake Tap Alternative Annual Demand 191196 MWhrs Minimum Pool Elev.: 1890 Storage KPU Summer 44339 MWhrs Pool Starting Elev.: 1959 3760 KPU Winter 103311 MWhrs Turbine Elev.: 150 ft Un—metSummer 13020 MWhrs Assumed Head Loss: 80 ft Un-—met Winter 30526 MWhrs Assumed Eff. 0.82 ___ Min. Instream Flo 698|. 4169| 4002 Nov 44.8 2547 4152 Dec 18.6 1021 4222 Jan 30.6 1759 3910 Feb 24.4 1255 3645 Mar 173 941 3773 Apr 25.0 1369 3410 1890 23.0 1890 May 61.1 3634 3391 1890 39.3, 1219 1903 3391 June 82.4 4784 3125 1916 36.7 3749 1937 3125 July 61.2 3640 3129 1958 35.1 3760 1959 3129 Aug 44.6 2619 3151 1959 353 3760 1959 3151 Sept 52.7 3017 3629 1959 42.0 3760 . 1959 3629 Ending Pool Elevation 1959 Total Generation 38387 SUMMARY OF GENERATION Un—Met Summer Load 13020 MWhrs Mahoney Summer Generation 13033 % Un—Met Summer Load 100% Un—Met Winter Load 30526 MWhrs Mahoney Winter Generation 25354 % Un—Met Winter Load - 83% Table 3-2 p:\hyd\mahoney\tab3—4.wk3 CAPE FOX CORPORATION MAHONEY LAKE HYDROELECTRIC PROJECT Average Annual Energy Generation — Year 2005 and Beyond Lake Tap Alternative Yearly Demand 198450 MWhrs Minimum Pool Elev.: KPU Summer 44339 MWhrs Pool Starting Elev.: KPU Winter 103311 MWhrs Turbine Elev.: Un-—metSummer 15196 MWhrs Assumed Head Loss: Un-—met Winter 35604 MWhrs Assumed Eff. 1890 Storage 1959 3760 150 ft 80 ft 0.82 2 cfs Min. Instream Flow: w | Ave : Turbme | = =—s«|_-«S Pool_~=|_:s- Monthly _ |Demand | | | Flow | Ending | Average | Enetey 10 | (cfs) | Storage | Elev | Generation 52.3 3760 1959 4668 Nov 44.8 2547 4842 1959 56.3 2957 1952 4842 Dec 18.6 1021 4924 1945 56.4 512 1923 4924 Jan 30.6 1759 4561 1901 36.9 0 1896 3175 Feb 24.4 1255 4251 1890 22.4 0 1890 1749 Mar 173 941 4401 1890 15.3 0 1890 1311 Apr 25.0 1369 3977 1890 23.0 0 1890 1907 | May. 61.1 3634 3956 1890. 45.9 810 1899 3956 June 82.4 4784 3647 1908 43.0 2948 1927 3647 July 61.2 3640 3652 1945 41.1 3760 1952 3652 Aug 44.6 2619 3677 1959 41.2 3760 1959 3677 Sept 52.7 3017 4235 1959 49.0 3760| 1959. 4235 Ending Pool Elevation 1959 Total Generation 41742 - SUMMARY OF GENERATION Un—Met Summer Load 15196 MWhrs Mahoney Summer Generation 15211 % Un—Met Summer Load 100% Un—Met Winter Load 35604 MWhrs Mahoney Winter Generation 26531 %o Un—Met Winter Load 15% Final Consultation Document 4.0 ENVIRONMENTAL AND REGULATORY ISSUES This section includes a description of the environmental setting, preliminary identification of environmental impacts from the proposed Project, possible agency concerns, and permitting requirements. The information contained herein should not be considered a complete environmental assessment. ENVIRONMENTAL ISSUES Topography The Project site is located in southeast Alaska approximately 5 air miles northeast of Ketchikan on Revillagigedo Island. The island is located at the south end of the Alexander Archipelago, which is a belt of mountainous islands off the coastal mainland. The island is roughly oval in shape, about 56 miles long and 42 miles wide. It has an area of 2,352 square miles. The highest peak on the island is 4,560 feet above sea level. In most places, the mountains rise sharply from the water’s edge, although there are a few areas of coastal lowlands along the southern shore of the island. Numerous lakes are distributed over the island, and countless short, swift streams flow down to the ocean. For this Project, water from Upper Mahoney Lake, at approximate El. 1,950 feet MSL, flows down a cascade (Upper Mahoney Creek) to the lower lake (El. 85) and then into George Inlet by way of Lower Mahoney Creek. Climate The Ketchikan area experiences a maritime climate with relatively mild, wet winters, cool summers, and heavy precipitation. According to the 1983 COE DEIS, the average annual precipitation for Ketchikan is approximately 154 inches, including 33 inches of snow. Average monthly temperature ranges from 34°F in January to 58.7°F in August. Prevailing winds in the Ketchikan area are from the southeast. The growing season extends from early May to early October. Local climatic patterns are strongly influenced by the mountainous topography of the region (COE, 1983). Water Quality Because of the pristine nature of the Project area, the quality of the water resources are high. Water quality has not been degraded due to limited human activity in the area. There also has been little natural degradation in the streams below the lakes because the lakes act as catchments, reducing the maximum sediment concentrations. Water quality may experience short-term impacts during construction. However, no significant degradation of a long-term nature is expected because the Project will utilize a lake tap on Upper Mahoney Lake Hydroelectric Project August 1994 17 FERC No. 11393 Final Consultation Document Mahoney Lake and water will flow underground through tunnels and pipe to the powerhouse at the base of the falls above Lower Mahoney Lake. Because the water is not exposed to the atmosphere at any time, problems related to gas supersaturation are not expected to occur. Temporary increases in levels of turbidity, suspended solids, and stream siltation may occur as a result of land clearing and other construction-related activities. An Erosion and Sediment Control Plan will be developed as part of the FERC License Application and it will be implemented during construction to control sources of potential sediment. Construction "Best Management Practices", including construction scheduling, care of water, erosion and sediment control measures, and re-vegetation plans will avoid or minimize problems associated with land disturbance. Fishery Resources Fish constitute an important recreational and economic resource of the Project area. A variety of fish species are found in the Mahoney Lakes area. Fishery studies were conducted in 1977 and again in 1982 by the U.S. Fish & Wildlife Service (USFWS) (Appendix B). The aquatic system including the lower lake and its outlet stream (Lower Mahoney Creek) is valuable for fish resources, particularly pink, chum, and sockeye salmon and resident Dolly Varden. Other species that may be present include coho salmon, kokanee (land-locked sockeye salmon), cutthroat trout, rainbow trout/steelhead, sculpins, and sticklebacks. As stated in the 1978 COE PDEIS, the USFWS reported Upper Mahoney Lake is devoid of fish. Grayling were stocked in the upper lake in 1966. However, stocking was apparently not successful as biological investigations conducted by the USFWS in 1977 did not indicate their presence (COE, 1978) (see Appendix C, Agency Correspondence). Lower Mahoney Lake provides habitat for anadromous sockeye salmon (COE, 1983; USFS, 1993) (Appendix C). Young anadromous sockeye rear in the lake for a year or more before migrating to the sea. Adult sockeye return to spawn along the western shoreline of the lake where there is an apparent upwelling derived at least in part from Upper Mahoney Creek. Sockeye spawning does not occur in Upper Mahoney Creek because of the turbulent flows and unpredictable flow patterns. Aerial counts taken in September 1982 totalled approximately 300 to 500 fish either spawning or returning to spawn. Pink and chum salmon spawn in Mahoney Creek and their fry migrate to the sea in the spring, soon after emergence from the stream gravel (COE, 1983). The powerhouse will be sited at the base of a large waterfall located at about El. 140. At this location, the steep cascades of Upper Mahoney Creek tumble over one last waterfall into a solid tock-lined bow] that marks the end of the cascades and the start of a meandering channel that leads about 800 feet downstream to Lower Mahoney Lake. This large waterfall precludes fish migration any further up Upper Mahoney Creek. Flows from the powerhouse will be returned to Upper Mahoney Creek at this point, above Lower Mahoney Lake. This was the arrangement preferred by the USFWS as stated in the 1983 COE DEIS. One alternative looked at in the 1970’s and 1980’s had placed a lake tap 225 feet below the surface of the upper lake, almost at the very bottom. Concerns had been raised previously as to whether or not the water temperature in Lower Mahoney Lake would drop as a result of drawing very cold water (4°C) down from Upper Mahoney Lake and adversely impacting salmon redds along the western edge of the lower Mahoney Lake Hydroelectric Project August 1994 18 FERC No. 11393 Final Consultation Document lake (see Appendix D-Temperature Information). The current proposal has located the lake tap approximately 75 feet below the surface of the upper lake to draw water down to the powerhouse via tunnels and pipe. The depth of water at the intake will vary between 5 and 75 feet throughout a normal operating year, depending on time of year, inflow to the lake, and energy demand. Temperature studies will be conducted to evaluate any impacts on sockeye salmon spawning habitat downstream in the lower lake. Botanical and Wildlife Resources Botanical Southeast Alaska has three general vegetative systems; coastal western hemlock-Sitka spruce forest, bogs or muskeg, and alpine tundra. The western hemlock-Sitka spruce forest system extends from sea level to treeline, which occurs at about 2,500 feet in the Ketchikan area. Most of the forest is mature growth, with some trees more than 200-feet tall, 14 feet in diameter, and more than 800-years old. The forest around the Project area is predominantly a mixed stand of western hemlock and Sitka spruce (COE, 1983). Western red cedar and Alaska cedar are also present in lesser percentages. In addition to these tree species, the forested areas support smaller growths of red alder, cottonwood, mountain hemlock, alpine fir, Pacific fir, and lodgepole pine. Forests have very dense canopy and understory layers blocking out most direct sunlight. Small bush saplings of shade-resistant hemlock and cedar, with blueberry, devilsclub, and other shrubs form a dense understory. Huckleberry, copper bush, Sitka alder, juniper, skunk cabbage, ferns, mosses, and grasses also contribute to this understory. Intermediate plant communities that combine elements of forest and bog grow near the forest edge. Characteristic plants of this vegetative type are shore pine, Alaska cedar, mountain hemlock, rusty menziesia, sedges, mosses, and rooted aquatics. As stated in the 1983 COE DEIS, bogs are the only type of wetland found near the Project area, along the south shore of the lower lake. This area is part of the access road/transmission line route. A wetlands delineation and assessment will be conducted as part of the environmental studies to confirm this finding. The alpine tundra occurs in open terrain above the treeline where barren rocks and rubble are interspersed with low plants including cassiopes, mountain-heath, dwarf blueberry, dwarf willow, avens, alpine azalea, lichens, and mosses. Although Upper Mahoney Lake is below El. 2,500, this type of vegetation is found in the area above the lake due to the rocky, steep terrain. Some vegetation will be lost due to constructing the powerhouse and access road/transmission line route, however, revegetation of disturbed areas will occur as soon as construction activities are completed. Because most of the Project features will be underground, the amount of disturbed area is reduced. Approximately 8 acres will be disturbed as a result of this Project, mostly from clearing forest for the access road/transmission route. Wildlife Mammals. The Project area is relatively productive for wildlife. Deer, black bear, and wolves are common species. Sitka black-tailed deer are found in varying abundance throughout the Project area and are probably the most important big game animal of the area (COE, 1978). Deer are common on some localized, good quality ranges but are scarce in the remainder of the Project area. Mahoney Lake Hydroelectric Project August 1994 19 FERC No. 11393 Final Consultation Document Populations have historically fluctuated, with extreme lows being greatest when winter conditions are severe and where wolves are present. During different seasons of the year, deer utilize most habitat types where food is available. Their home range is usually small, but they do make vertical migrations from the beach to alpine areas as a result of snow depths and availability of food. During much of the year, low-growing forbs are the most important plant species used. Summer food is usually not a limiting factor. During severe winters when snow depth is excessive, mortality often occurs because travel becomes difficult and forage is covered. Moose and brown bear are not found on Revillagigedo Island, however, black bears are abundant throughout the timbered and adjacent portions of the Project area and, with the exception of deer, are the most commonly encountered big game animal. The areas in which black bears occur coincide closely with the distribution of forests but seasonal concentrations occur along beaches and tideflat areas in the spring and along salmon creeks in late summer and fall. Black bears prefer semi-open forests rather than dense stands of timber. Semi-open forested areas with understory composed of fruit-bearing shrubs and herbs, lush grasses and succulent forbs are particularly attractive. In the spring, black bears are frequently found in moist lowlands where early growing green vegetation is available. The sedge and grass found in low-lying intertidal areas are particularly important. Black bears spend the summer months in berry-producing areas ranging from sea level to alpine regions. Salmon become an important food item in late August and September at which time spawning is completed, with the exception of some streams with late chum and coho runs, which last into November. Hunting of black bears in the Project area is considered light in intensity (COE, 1983). Wolves occur throughout the Project area with abundance varying greatly between areas and from year to year. Wolf populations on Revillagigedo Island reach greater densities than on the mainland because deer are important wolf prey on islands and are more abundant and vulnerable than mountain goats, the primary mainland wolf prey. Natural controls of wolf populations seem to be related to abundance and availability of prey. The USFS reported that fifteen mountain goats had been transplanted to the alpine area surrounding Upper Mahoney Lake in 1991 (Appendix C). All of the proposed Project features are located below El. 1950 with only two structures and one new access road at elevation 180. Some limited disturbance of goats may occur during Project construction. Once operational, the Project will convey water through underground structures so no migration barriers will exist. Therefore, impacts to goats are anticipated to be minor. Other mammals which may be present in the Project area include lynx, wolverine, red fox, land otter, mink, marten, short-tailed weasel, fisher, beaver, muskrat, and snowshoe hare. Birds. Southeast Alaska supports breeding populations of waterfowl, but the region is used mostly for stopover during spring and fall migrations with some overwintering species. Bays and fjords are important for this purpose. However, waterfowl are not attracted to the Project area because it lacks suitable habitat (COE, 1983). The bald eagle is the most common raptor of southeast Alaska and a few nests have been found north of the Project site (COE, 1983). There are also a few ospreys and a few golden eagles present in the area (COE, 1978). Mahoney Lake Hydroelectric Project August 1994 20 FERC No. 11393 Final Consultation Document While the region has several large colonies of sea birds, none are located proximate to the Project area. Shorebirds such as killdeers, semi-palmated plovers, sandpipers, and oyster catchers probably occur within the Project area. Other shorebirds are migrant. Rock ptarmigan, willow ptarmigan, and blue grouse are resident game birds. Temporary disturbance of mammal and bird populations will result from construction-related activities and increased hunting pressure on game populations in the lowland areas could occur. Because access roads are not proposed for the upper Project area, no significant upland hunting pressure changes are anticipated. While some alteration of existing wildlife habitat will occur as a result of the proposed Project, the impacts of this alteration are not considered to be entirely negative because certain improved habitat conditions may result. These improved conditions may provide greater interspersion of vegetation types and creation of uneven-aged forest stands which improve browse quality for deer and other wildlife species. The 1983 COE DEIS reported the proposed Project at that time would have little or no effect on bald eagles but it is likely an eagle nest survey will need to be conducted. Transmission lines will be designed to protect raptors from possible electrocution by providing hunting perches and/or by use of approved raptor-proof designs. Threatened and Endangered Species. According to the 1983 COE DEIS, there were no species listed by either the USFWS or the National Marine Fisheries Service as threatened or endangered in the Project area at that time (Appendix C). This information will be updated prior to final design of the Project. Cultural Resources Knowledge of the prehistoric period for southeast Alaska is quite sketchy, although it is known that Tlingit Indians long had fish camps near the present City of Ketchikan and that they had a village at Ketchikan Creek. A petroglyph has been reported near Mahoney Lake in the vicinity of the cove east of the lower lake and an abandoned mine is located near the mouth of Mahoney Creek. As stated in the 1983 COE DEIS, the Project would have no impacts on cultural resources as proposed at that time. An intensive cultural resources survey of the Project area in 1981 did not locate any significant historical or archaeological sites (COE, 1983). There are no known sites eligible for the National Register of Historic Places in the vicinity of the Project. A cultural resource survey will be conducted to assess the proposed areas of disturbance. Socioeconomic Ketchikan is the fourth largest city in Alaska. Major industries that effect Ketchikan’s local economy include fishing, forestry, mining, government, tourism, and commerce. Most of these industries experience seasonal swings in employment. Unemployment rates for Ketchikan (city and borough) in 1993 ranged from a low of 5.9% in August to a high in January of 15.4%. As of September 1993, the population of Ketchikan was 14,000 (Alaska Department of Labor, 1993). Mahoney Lake Hydroelectric Project August 1994 21 FERC No. 11393 Final Consultation Document Improved access to previously undisturbed forest lands would increase the potential to utilize the timber and mineral resources of the area, along with providing low cost, renewable energy to the Ketchikan area. Geology Most of southeast Alaska’s present land forms developed from the action of glaciation and volcanism during the Quaternary period, which is the most recent period of geologic time. At the height of this activity, glaciers not only covered nearly all of the land, but also extended miles out over the ocean as a gigantic sheet of ice. Remaining today as evidence of glacial action are the numerous cirques and fjords. Numbers of the fjords formed along faults or joints, mainly as a result of glacial scouring along existing river valleys. The site is crossed by faults and lineaments that are probably indicative of minor shear zones in the bedrock. Slope instability in this area is primarily rock falls and small to moderate size rock slides (Shannon & Wilson, Inc., 1993) (Appendix E). Three belts of metamorphic rock and sedimentary rock trend northwest throughout the region. On Revillagigedo Island, metamorphic and sedimentary rocks dip steeply westward, and strike to the northeast. The common rock of the area consists of a metamorphic belt of schist and phyllite intermingled with smaller intrusions of quartz diorite (Shannon & Wilson, 1993). The area is classified as Seismic Zone 3, moderate risk (COE, 1978). Further information about site specific geology is contained in Appendix E. Recreation Fishing, boating, hunting, camping, and picnicking are all very popular among residents and tourists of Ketchikan, which is surrounded by the Tongass National Forest. Sport fishing, largely for salmon and halibut, is very popular. The many miles of shoreline in the area afford opportunities for beachcombing for shells, fish floats, etc. Hunting is a major recreational activity. The Sitka black-tail deer is the most sought after game animal, with bears also attracting hunters. The USES has constructed and maintains numerous hiking trails with cabins for public use in southeast Alaska. These cabins are usually located on lakes which provide fishing opportunities, however, none exist within the Project area. Sightseeing is also popular since the area has spectacular scenery produced by the mountains, waters, and forests. As stated earlier, Upper Mahoney Lake lacks fish; there are some fish species in the lower lake. The Mahoney Lakes system receives little angling pressure due to the relative remoteness of the site and small populations of fish (COE, 1983). Increased access to forest lands increases the opportunity for dispersed recreation. However, significant changes in recreation patterns of the Ketchikan area are not anticipated due to construction of the Project. Mahoney Lake Hydroelectric Project August 1994 22 FERC No. 11393 Final Consultation Document Aesthetics Scenic values abound in this largely undeveloped region. Myriad islands, a deeply indented coastline, forests, mountains, glaciers, and the ocean combine to form superb vistas. The study area ranks high in all elements of aesthetic quality including vividness, visual intactness, unity, and visual uniqueness (COE, 1978). The aesthetic quality of the proposed Project area would be affected by reduced streamflow. Most of the flows that form the waterfall at the outlet of the upper lake would be diverted for power generation. Visual impacts caused by the Project features will be minimal since almost all of the Project features will be placed underground. The transmission line will be buried along the proposed access road for approximately 0.8 mile from the powerhouse to a point southeast of Lower Mahoney Lake. The line will continue north along an existing logging access road another 5.2 miles on overhead pole structures to an intertie with the existing Swan Lake transmission line. Land Use The proposed Project would be sited on land owned by the USFS and the Cape Fox Corporation. Project features that would be located on USFS land include the lake tap, the vertical shaft, a majority of the upper and lower tunnels, and a short section of the access road/transmission line route. A Special Use Permit would be required for this portion of the Project and any proposed development would have to be consistent with the Tongass National Forest Plan. The powerhouse, and most of the access road/transmission line route would be sited on land owned by the Cape Fox Corporation. This land was selected by the Cape Fox Corporation under terms of the Alaska Native Claims Settlement Act. REGULATORY ISSUES In addition to the FERC License, other environmental and regulatory permits that may be required for the Project are listed below. Upon FERC approval of the Final License Application and after the public notice has been issued, a package of the following permit applications will be submitted to the Alaska Division of Governmental Coordination (ADGC) and the COE. The ADGC will then distribute the permit applications to the appropriate agency for review. s A Water Rights permit issued by the Alaska Department of Natural Resources. An application for this permit has been submitted. be Under Section 401 of the Federal Water Pollution Control Act, a Certificate of Reasonable Assurance is required from the Alaska Department of Environmental Conservation. A request letter will be sent prior to submittal of the Final License Application and a letter of receipt will be issued by the ADGC. a A Section 404 Permit is required from the COE by the Federal Water Pollution Control Act if activities include discharge of dredge or fill materials into waters of the U.S and/or significant wetland disturbance. - Mahoney Lake Hydroelectric Project August 1994 23 FERC No. 11393 August 1994 Final Consultation Document A Special Use Permit will be required from the USFS for development of the upper portion of the Project. An application has been submitted for an Investigative Special Use Permit to study the Project area and a section of road north of the Mahoney Lake outlet creek. An application has also been submitted to conduct a cultural resource survey on USFS lands. Consistency with the Alaska Coastal Management Program is required and the necessary review is conducted by the ADGC. Ketchikan has a local coastal plan and Ketchikan Gateway Borough will issue a certification of consistency with their plan for the Project. A local zoning permit will also be obtained from the Ketchikan Gateway Borough. A fish habitat permit will be obtained from the Alaska Department of Fish and Game for instream work. A NPDES stormwater permit will be obtained from the EPA. Mahoney Lake Hydroelectric Project 24 FERC No. 11393 Final Consultation Document 5.0 STREAMFLOW AND WATER REGIME GENERAL The proposed Project will utilize runoff from a 2.0 square mile drainage area supplying Upper Mahoney Lake. The lake lies within the region of maritime influence of southeastern Alaska as shown on Figure 1-1. The area receives limited sunshine, abundant precipitation, and generally moderate temperatures. The area’s rugged terrain causes considerable variations over short distances for both precipitation and local temperatures. A hydrologic analysis was conducted in order to develop streamflow data that could be used for estimating average annual energy generation. Several previous studies of streamflow hydrology have been conducted in the past, and these were reviewed before this analysis was conducted. The methodology and results of the hydrologic analysis performed are described below. A flood frequency analysis for the Project site was also conducted. DERIVATION OF LONG TERM DAILY FLOW DATABASE Daily streamflow data has been recorded at the outlet to Upper Mahoney Lake for water years 1978 to 1989 (USGS Gage #15067900). The gage is considered to be an accurate representation of flow available for diversion. Table 5-1 presents average monthly flows at the gage for the years 1978 to 1989. Based on this 12-year period of record, the average annual outflow from Upper Mahoney Lake is 43 cfs. As explained below, an additional 23 years of streamflow records were developed to provide a long-term hydrologic data base. Based on the 35-year period of actual and synthesized data, the average annual outflow from Upper Mahoney Lake is estimated to be 44.4 cfs as shown on Table 5-1. This compares to previous estimates of 46 cfs (Beck, 1977) and 48 cfs (COE, 1978). In order to obtain an extended period of record of daily flows for the diversion site, flows for years other than the period of record (1978 - 1989) were synthesized by correlating the gage at the diversion site (#15067900) to gage #15068000, Mahoney Creek near Ketchikan, Alaska. The drainage area of gage #15068000 is 5.7 square miles and includes the 2 square miles contributing to gage #15067900. The period of record for gage #15068000 is 1920-1933, 1947- 1958, and 1977-1981. This gage and the gage at the diversion site have an overlapping period of record for the years 1978 to 1981. First, an attempt was made to correlate the two gages on a monthly basis, producing a separate equation relating flows for each month. However, this resulted in correlation coefficients (1°) that varied from 0.98 to 0.01. Six of the 12 monthly coefficients were considered poor. Attempts were also made to correlate the gages on a seasonal basis. This also produced correlation coefficients that were too low to be statistically acceptable. Mahoney Lake Hydroelectric Project August 1994 25 FERC No. 11393 Final Consultation Document The reason for the poor monthly and seasonal correlations is attributed to the fact that the mean basin elevation for the diversion site is approximately 2,350 feet, while the mean basin elevation for the Mahoney Creek gage is approximately 1,130 feet. The upper basin receives considerably more precipitation than the lower basin and most of the additional precipitation at the upper basin occurs in the form of snow. Finally, the gages were correlated on a yearly basis, resulting in a correlation coefficient of 0.70, which is considered acceptable. Basically, this is a correlation of annual flow volumes between the two gages. A search for a hydrologically similar gaged basin in the vicinity of the diversion site was performed in an attempt to achieve a better correlation. However, a search for a gage with an extended period of record which overlaps the gage near the diversion site revealed no usable gages within a 100 mile radius of the proposed diversion site. Therefore, the gage at Mahoney Creek was used. The relationship between the two gages as established by the linear correlation is Y = 0.41X + 1.8, where X = flow at Mahoney Creek and Y = flow at the diversion site. The above equation was applied to the gage at Mahoney Creek for the years 1921-1925, 1927- 1933, and 1948-1958. These are the years of complete records of daily flow at the Mahoney Creek gage. As stated above, since the correlation between the two gages relates only annual volume, monthly adjustment factors were applied to the synthesized daily flow at the upper gage, causing the monthly percentages of the annual average of the synthesized data to match the monthly percentages of the actual gaged data at the diversion site, while maintaining the correlated volume. These 23 years of synthesized daily flows, added to the 12 years of historical flows, provide 35 years of data at the diversion site. Table 5-1 also shows the average monthly flows at the diversion site for the 35-year period of record. Figure 5-1 shows a flow- duration curve for the diversion site for the 35-year period. Actual daily flows for 1978-1989 and simulated flows for the years 1921-1925, 1927-1933, and 1948-1958 are shown in Appendix F. Based on the 15% exceedence value from the flow duration curve, a discharge of 78 cfs was selected for the turbine design hydraulic capacity. This flow was used to size water conveyance facilities and in the energy generation analysis. TABLE 5-1 UPPER MAHONEY LAKE AVERAGE MONTHLY FLOW Mahoney Lake Hydroelectric Project August 1994 26 FERC No. 11393 p:lhyd\mahoneylupmahnoy.xls 9/22/93 FIGURE 5-1 UPPER MAHONEY LAKE Flow Duration Curve 120 100 T FLOW (cfs) 8 ~—— 40 20 + of 0 20 40 60 80 100 % EXCEEDANCE NOTE: 1. Based on 12 years of actual records and 23 years of synthesized data. Final Consultation Document FLOOD FREQUENCY ANALYSIS Peak annual flows recorded at the Upper Mahoney Lake Outlet (gage # 15067900) for the period of record from 1979 to 1989 were used in computing expected flood frequencies at the diversion site. The computer program, HECWRC, developed by the COE was used to facilitate the analysis. The program computes flood frequencies by fitting the peak annual flows for a period of record to the Log-Pearson Type III distribution in accordance with guidelines established by the USGS Bulletin 17B. Using HECWRC, the magnitude of the expected 100-year discharge was computed to be 1,740 cfs. This flood magnitude can be used later for siting structures to be sure they are above flood-influence zones. Upper Mahone ke Ca In 1983, the COE developed detailed area capacity curves for Upper Mahoney Lake based on soundings of lake depth (see Appendix F, Hydrology Information, Figure A-15). Mahoney Lake Hydroelectric Project August 1994 28 FERC No. 11393 Final Consultation Document 6.0 PURPA BENEFITS The Applicant will seek benefits under Section 10 of PURPA. The Project will be located at a new diversion as defined in 18 CFR 292.202. Mahoney Lake Hydroelectric Project August 1994 29 FERC No. 11393 Final Consultation Document 7.0 LICENSING STUDY PLANS The following paragraphs describe the study plans and associated methodologies that will be used to evaluate the impacts of, and to develop mitigation and/or compensatory measures for developing the Mahoney Lake Hydroelectric Project. Considerable information and existing data already exists regarding the Project and the Project area. As stated earlier, detailed studies were conducted in the late 1970’s and early 1980’s in consideration of developing a hydroelectric project at that time. The outlined study plans reflect the fact that considerable study work has already been completed. The study plans have been modified as a result of comments that were received during the Stage I consultation process. To the extent possible, preliminary results of the studies will be distributed to interested parties for their review and comment prior to distribution of the Draft License Application. WATER QUALITY AND QUANTITY Purpose The purpose of these studies is to determine pre-project baseline water quality conditions in Mahoney Creek at the powerhouse tailrace site. In addition, these studies will investigate relationships between water temperature and air temperature at the powerhouse site and water temperature in the spawning gravels at the western end of Lower Mahoney Lake to aid in predicting post-project water temperatures in these gravels. Methods Agencies will be consulted and existing information collected. Additional study tasks will be conducted including literature review, and water quality and quantity measurements. Agencies to Be Consulted U.S. Forest Service (USFS) U.S. Geological Service (USGS) U.S. Fish and Wildlife Service (USFWS) U.S. Corps of Engineers (COE) Alaska Department of Natural Resources (ADNR) Alaska Department of Fish and Game (ADFG) Alaska Department of Environmental Conservation (ADEC) Ketchikan Gateway Borough Alaska Resources Library Mahoney Lake Hydroelectric Project August 1994 30 FERC No. 11393 Final Consultation Document Existing Information Water Quality Existing temperature data will be updated (See Appendix D). Sources of existing information may include USFWS, USGS, COE, and ADNR, or other agencies listed above. Study Tasks Literature Review The applicant will collect existing water quality information for the project area, contacting the following agencies in writing: USFS USGS USFWS COE ADNR ADFG ADEC Ketchikan Gateway Borough Alaska Resources Library The information collected will be incorporated into Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. Data Collection Data will be collected for one year beginning in June of 1994. Data collection will consist of: Continuous air and water temperature monitoring and continuous stream flow monitoring. The following continuous monitoring data will be collected: = Continuous lake water temperature data at Upper Mahoney Lake at 20, 40, 60, 80, and 100 foot depths and just below the maximum estimated depth of ice formation (to protect the probe from damage by ice movement). . Continuous stream flow and stream water temperature data in the creek at the tailrace site. This sampling station will be established for stream flow monitoring throughout the life of the project. a Continuous air temperature data at eight feet above the ground surface at the powerhouse tailrace site. a Continuous water temperature data at two sockeye spawning sites near the outlet of Upper Mahoney Creek at the western end of Lower Mahoney Lake. At each site, measurements will be taken at a depth of 10 inches in the spawning gravels and at four inches above those gravels. Mahoney Lake Hydroelectric Project August 1994 31 FERC No. 11393 Final Consultation Document Air and water temperature and stream flow data will be collected with battery operated electronic data collection devices. It is anticipated that all data logging devices will be Dryden Instrumentation model R2 dataloggers. Sensors will be scanned at two hour intervals, continuously for one year, except for the stream gauge which will be maintained for the life of the project. Monthly water quality sampling. Dissolved oxygen, pH, turbidity, and total suspended solids will be measured at the powerhouse tailrace site monthly during summer and bi-monthly as snow-free winter conditions permit. Dissolved oxygen will also be measured in Lower Mahoney Lake at the surface of the spawning gravels at these times. Periodic temperature and dissolved oxygen profile measurements. In addition to the continuous monitoring data and monthly sampling, sampling crews will take measurements to develop temperature and dissolved oxygen profiles at Upper Mahoney Lake at five times: a When temperature sensors are installed at the beginning of the study. . At maximum summer stratification development—approximately late July—and after at least three consecutive mostly clear, rain-free days. s Coinciding with the normal date the sockeye salmon spawn— about September 1—and after at least two rain-free days. a At maximum winter ice development—approximately late January—and after at least five below-freezing, precipitation-free days. a When temperature sensors are removed at the end of the study. The profiles will be developed for the deepest point of Upper Mahoney Lake by recording the temperature at 2-foot intervals for the first 60 feet and 10-foot intervals thereafter to a depth of 120 feet. Data Analysis Temperature data will be analyzed to see if relationships exist between stream flow, stream temperature, and air temperature at the powerhouse site and the spawning gravel water temperature at the Lower Mahoney Lake sites. If possible these data will be used to predict post-project water temperatures at the spawning sites using water temperature data collected at Upper Mahoney Lake. This relationship could then be used to assess whether methods to mitigate temperature impacts on salmon egg incubation sites should be considered. Stream flow data will be analyzed to compare the flow regime during the sampling year to the average flow condition estimated from stream gauging records. Mahoney Lake Hydroelectric Project August 1994 32 FERC No. 11393 Final Consultation Document FISHERIES AND AQUATIC RESOURCES Purpose Objectives of the fisheries and aquatic studies are to: a) determine existing fisheries resources above, within, and below the diversion reach; b) determine the potential Project impact on fisheries resources; and, c) develop measures to avoid, minimize, and mitigate impacts on fisheries resources. Methods Agencies will be consulted and existing information collected. Additional studies to be conducted include: - Fish population surveys Agencies to be Consulted USFWS National Marine Fisheries Service (NMFS) USFS COE ADFG Existing Information Information for the Mahoney Lake drainage may be available from the USFWS, NMFS, COE, USFS, and the ADFG from previous studies. Some of the existing information is included in Appendix B. Tasks Fish Population Surveys Fish abundance and utilization will be surveyed in Mahoney Creek from its mouth in Lower Mahoney Lake upstream to the major waterfall two times per year - June and early September in 1994, Visual observations as well as electroshocking and minnow trapping will be used to determine the presence, abundance, and habitat utilization of major fish species. Emphasis will be on a determination of value to rearing juvenile salmonids as well as value to spawning adults. Confirmation of reports that the streambed is sometimes dry will be made. The abundance and location of lake spawning sockeye salmon will be carefully investigated with emphasis on the western end of Lower Mahoney Lake near the outlet of Upper Mahoney Creek. Observations of likely spawning areas will be made by local residents weekly beginning in late July and continuing until late September. The biological team will conduct detailed surveys at least twice during the peak of spawning as determined from the weekly observations. Methods to be utilized will include aerial visual surveys and boat-based visual surveys. Mahoney Lake Hydroelectric Project August 1994 33 FERC No. 11393 Final Consultation Document In addition, general surveys of Lower Mahoney Lake will be conducted in June and September to gain insight into the use of the lake by rearing and resident fish. Methods will include visual observations, minnow traps, fine mesh seine, and angling. Fish abundance and utilization will be surveyed in Lower Mahoney Creek from its mouth upstream to Lower Mahoney Lake at least two times in 1994, June and early September. Visual observations and minnow trapping will be used to determine the presence, abundance, and habitat utilization of major fish species. Emphasis will be on a determination of value to adult salmon spawners. Results Information obtained from the temperature modelling and analysis study component will be combined with the results of the fish studies to provide an indication of the kinds of effects that the Project might have on fish productivity. Emphasis will be on the potential effects of any altered temperature regimes on sockeye salmon eggs incubating in lake gravels and on the kinds of mitigation measures that could be employed to alleviate such effects. The Fisheries Resource section will be prepared incorporating the study results and in accordance with the appropriate regulations. Information collected will be presented in draft reports and provided to the agencies of record for their comments. After review, any appropriate adjustments to the drafts will be incorporated into the final reports. WILDLIFE AND BOTANICAL RESOURCES Purpose The purposes of the wildlife and botanical studies are to: map and describe general habitat types, including wetlands; describe probable wildlife use of the project area; and determine the probability of threatened, endangered, and sensitive species occurrence in the project area. The potential impact of the project on these resources will also be evaluated and measures to avoid, minimize, or mitigate impacts will be developed. Methods Because vegetation types and wildlife occurrence are closely related, these resources will be studied simultaneously. These studies will include review of previously compiled information; interpretation of aerial photography; consultation with resource agencies; a brief field investigation; analysis of potential impacts; and development of mitigation measures. Mahoney Lake Hydroelectric Project August 1994 34 FERC No. 11393 Final Consultation Document Agencies to be Consulted: USFWS USFS NMES ADFG Alaska Natural Heritage Program Ketchikan Gateway Borough Cape Fox Corporation Tasks Existing Information Previously compiled information on plants, habitat types, wildlife, and wetlands will be reviewed. Aerial photography will be interpreted to produce preliminary habitat and wetland maps. Pertinent personnel of the above agencies will be contacted to ascertain whether additional written information is available, to interview them regarding resources they know or suspect to be present in the project area, and to clarify their concerns about the potential impacts of the project. Consultation required by Section 7 of the Endangered Species Act will be initiated with the USFWS and NMEFS, and a list of "sensitive" species will be requested from the USFS. Bald eagle nest information will be sought and reviewed. Field Surveys A single site visit will be made during summer of 1994 to conduct the following activities in the area of the lake tap tunnel/vertical shaft connection, powerhouse, and the new access road. Preliminary wetland and habitat type maps will be field checked, and wetlands and other habitat types will be qualitatively described. Any unusual habitat types will be noted. Field observations of mammal and bird sign will be made while walking the project alignment. In addition to actual sightings, these may include identification of calls, tracks, and scat. Habitats that may support threatened, endangered, and sensitive species will be identified and, if such habitats are found, a reconnaissance-level search for those species will be conducted. A survey will be conducted from a helicopter to locate bald eagle nests and ascertain their current activity status. This will be conducted in cooperation with USFWS personnel. Analysis Results of the review of existing information, discussions with agency personnel, and field surveys will be used to assess the potential effects of the project on wildlife, their habitats, wetlands, and species of special concern. Species of concern to be addressed will include, at a minimum, bald eagle, American and arctic peregrine falcons, Alexander Archipelago wolf, and northern goshawk. In consultation with resource agencies, measures to mitigate potential impacts on project area resources will be identified and incorporated into the project plans. Mitigation planning will include development of measures to minimize potential collisions of large birds with the overhead electrical transmission line and to minimize the potential for electrocution of raptors. Mahoney Lake Hydroelectric Project August 1994 35 FERC No. 11393 Final Consultation Document Results The results of the above tasks will be presented in a draft report and provided to pertinent agencies for their comments. After review, appropriate adjustments to the draft will be incorporated into the final report. The format for the report will conform with the requirements for Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. HISTORIC AND ARCHAEOLOGICAL RESOURCES Purpose The purpose of these studies is to develop information on the nature and distribution of cultural Tesources within the Project area. This information, together with professional opinions and consultations with affected Native American groups and agencies, will be presented in a written cultural resources report for inclusion in the Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. Methods Agencies and Native American groups will be consulted and background research will be conducted. An archaeological/cultural resources field survey will also be performed. Study Tasks Background Research Background research will be conducted on the prehistoric, ethnohistoric, and historic use of lands within and around the Project area. Survey records and cultural resource inventories and registers maintained by the Alaska State Historic Preservation Office (SHPO) will be reviewed. Native American and Agency Consultation The Cape Fox Corporation and other interested Native American groups will be consulted to identify potential cultural heritage or traditional religious resources or concems in the Project area. If the archeological field survey locates prehistoric and/or ethnohistoric cultural resources, these grouped will be provided information on the resources, which will remain confidential. The SHPO and the USFS will also be consulted during the cultural resources assessment to ensure compliance with FERC regulations and the requirements of Section 106 of the National Historic Preservation Act, as amended. Archeological Field Survey An archeological field survey of the areas to be disturbed by the proposed site development will be conducted. Maps and aerial photographs will be used in conjunction with information on past land use and previously recorded cultural resources to identify geomorphic features within the Project area. Mahoney Lake Hydroelectric Project August 1994 36 FERC No. 11393 Final Consultation Document Environmental and geomorphic information will be recorded for areas surveyed. The location, condition, and potential significance of cultural resources identified during the field survey will be recorded on site forms acceptable to the SHPO. Field work will be documented with notes, drawings, and photographs as needed to record field methods and results. Mitigation measures will be recommended if the Project would produce adverse effects on any cultural resources found. Results The results of the cultural resources investigations will be presented in two reports: 1) a cultural resources background report; and 2) a summary document for Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. Draft copies of each report will be circulated for review, after which comments will be incorporated into the final reports. RECREATIONAL RESOURCES Purpose The purpose of the recreational resources study is to identify information regarding existing recreation use, future demand and opportunities, and the potential impacts on recreation resulting from development of the Mahoney Lake Project. This information, together with results of consultations with affected agencies and other interested parties, will be presented in a written Recreation Resources Report for inclusion in the Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. Methods Agencies will be consulted and existing information will be collected. Development of the Recreation Plan will include three phases. Phase I will identify the current recreation types and existing facilities. Phase II will include the evaluation of existing and future recreation demands in the Project area. Phase I will identify the potential impacts created by the Project on recreation and will evaluate alternatives, recommend mitigation and provide costs, if necessary. Study Tasks Phase I - Evaluation of Existing Recreation Resources Data Collection. The area in which the Project will have an impact will be identified and existing information will be collected. Data to be collected include maps; recreation guides; the USFS Recreation Resource Information System, Recreation Opportunity Spectrum, and the Tongass National Forest Plan; and other sources of recreation information, such as state agencies. Information regarding demographic use will also be gathered. Consultation. Consultations will be held with the agencies who are responsible for recreation planning and management within the Project impact area. Current direction and policies for Mahoney Lake Hydroelectric Project August 1994 37 FERC No. 11393 Final Consultation Document these agencies will be determined. Other agencies and native organizations which might track or project recreation use in the area such as local, county, and state administering agencies, will be contacted. Special-interest groups, local residents, and businesses that focus on recreation and tourism will also be consulted. Identify and Map Existing Facilities. From data collected, existing recreation facilities will be mapped for the Project area. Any National Wild and Scenic Rivers systems, National Trail systems, and Wilderness areas within the Project area will be identified. Phase II - Evaluate Recreation Demand Evaluate Recreation Potential. Existing recreation facilities in terms of activity type, physical setting, experience required, economic costs, and current demand will be evaluated. Future recreation use within the Project area will be identified and evaluated. Estimate Demand. Anticipated recreation demand with and without the proposed Project modifications will be estimated using demographic data. The demand projections will be correlated to regional opportunities for similar recreation. Constraints on development of recreation facilities will be identified. Phase III - Evaluate Project Impacts on Existing and Future Recreation Project Impacts. Potential environmental, social, and economic impacts created by the Project regarding existing and future recreation in the Project area will be identified. Alternatives will be identified based on data collected, associated impacts, constraints, and demand projections. If appropriate, mitigation measures will be recommended if it is determined the Project will produce adverse effects. Costs will be estimated for any new facilities and transportation access, plus operation and maintenance costs. Consultation. Agencies, native organizations, and special-interest groups who focus on recreation and tourism will be consulted regarding potential Project impacts. Results The data, maps, and study objectives information will be presented in a draft report and shared with the agencies of record for their comments. After review, any appropriate adjustments to the draft will be incorporated into the final report. AESTHETIC RESOURCES Purpose The primary purpose of the aesthetics study is to describe measures proposed by the Applicant to make Project facilities blend, to the extent possible with the surrounding environment, and to evaluate aesthetic impacts of proposed changes in stream flow. Inventory and effects Mahoney Lake Hydroelectric Project August 1994 38 FERC No. 11393 Final Consultation Document assessment activities will be conducted in order to identify and support any proposals for aesthetic treatments of Project facilities. Methods The aesthetics study will evaluate existing visual conditions, assess Project effects, and identify potential mitigation measures. Existing Visual Conditions A summary of existing visual conditions that addresses both Project facilities and the adjacent landscape will be addressed. Existing visual resource data related to the Project area, including the USFS Visual Management System, will be reviewed. Landscape character of the Project area will also be described. Approximate seen areas from selected viewpoints at and near the Project will be identified. Project Effects Assessment The effects of the proposed Project facilities on visual quality will be determined and presented in the report. This discussion will address the visibility of Project features from the selected viewpoints and will evaluate these views within the local visual context. The primary focus of this assessment will be impacts of reduced water flows over the waterfalls between Upper and Lower Mahoney Lakes and the impact of Project roads and powerhouse construction. Proposed Aesthetic Measures Potential measures that will reduce the visual contrast of Project features with the surrounding environment will be identified and their feasibility will be reviewed. Results The results of the aesthetics study will be presented in the Aesthetic Resources Report of Exhibit E of the FERC License Application and/or the Applicant-prepared Environmental Assessment. A draft report will be prepared and distributed to agencies of record for their comments. After their review and comment, a final report incorporating comments will be prepared. EROSION AND SEDIMENT CONTROL PLAN Purpose The purpose of the erosion and sediment control studies is to evaluate the potential for erosion and sedimentation during proposed Project construction and operation. Based on this evaluation, an Erosion and Sediment Control Plan (ESCP) will be developed to provide guidelines for controlling erosion and sedimentation during Project construction and operation activities. Since most of the Project features are underground, the ESCP will concentrate on access roads and tunnel spoils disposal sites. Mahoney Lake Hydroelectric Project August 1994 39 FERC No. 11393 Final Consultation Document Methods The ESCP will establish baseline conditions in order to assess potential impacts and allow comparison with conditions during Project construction and operational phases; identify existing environmental hazards which must be taken into account during Project design, construction, and operation; and identify measures which will minimize potential adverse impacts. Agencies to be Consulted USFWS NMFS USFS COE ADNR ADFG Tasks The following tasks will be performed in order to prepare the ESCP: 1. Existing site conditions will be evaluated including climate, topography, geology, soils, vegetation, surface and groundwater drainage, adjacent waterways, and hazard areas. 2s Erosion/sedimentation potential during construction of Project features and during Project _ operation will be determined. 3: Estimates will be made on the amount of tunnel spoils and locations for disposal sites will be identified. 4. Timing of construction activities will be identified and evaluated in terms of alleviating erosion potential. 3: Specific locations and techniques for controlling potential erosion and sedimentation during Project construction and operation will be identified, mapped, and detailed drawings and descriptions of such measures will be prepared. 6. Implementation guidelines for general and site specific erosion control measures will be developed. ie A revegetation plan for disturbed areas will be developed. 8. Procedures for maintenance and monitoring of erosion control measures for plan modifications will be developed. 9. Using existing information from geologic reports, mapping, aerial photos or other sources, a qualitative review of the Mahoney Lake drainage basin will be made which Mahoney Lake Hydroelectric Project August 1994 40 FERC No. 11393 Final Consultation Document will provide a general characterization of sources and types of sediment inputs into the river. The Universal Soil Loss Equation or another acceptable method may be used to estimate sediment delivery to Lower Mahoney Lake. To the extent feasible, (given the dynamics of the system), the relationship between geomorphic processes, Project operation, and sediment delivery will be characterized and discussed. Results A Draft ESCP will be prepared that details the Project area geology and soils, and characteristics of the Project segments. This report will include maps that illustrate the geologic and geomorphic conditions of the Project area. Upon completion, the report will be circulated to the appropriate agencies for comment and review. Following any necessary revisions, the report will be finalized and included as an appendix of the License Application. Mahoney Lake Hydroelectric Project August 1994 41 FERC No. 11393 Final Consultation Document 8.0 BIBLIOGRAPHY CH2M Hill. May 1986. Power Supply Planning. Institute of Social and Economic Research, University of Alaska, Anchorage. June 1990. Electric Load Forecast for Ketchikan, Metkalata, Petersburg, and Wrangell, Alaska: 1990-2010. Final Report. Nuveen, John & Co. Incorporated. June 1992. Bond Prospectus, Municipal Utilities Revenue, Series R, City of Ketchikan, Alaska. R. W. Beck and Associates, Inc. June 1977. Appraisal Report. Swan Lake, Lake Grace and Mahoney Lake Hydroelectric Projects. R. W. Beck and Associates, Inc. March 1986. Appraisal Study 1985 Update. Future Hydropower Resources. Ketchikan, Petersburg, Wrangell and Quartz Hill. U.S. Army Corps of Engineers, Alaska District, Anchorage, Alaska. 1978. Draft Environmental Impact Statement. Proposed Mahoney Lakes Hydropower Project, Ketchikan, Alaska. U.S. Army Corps of Engineers, Alaska District, Anchorage, Alaska. July 1983. Rivers and Harbors in Alaska, Draft Interim Feasibility Report and Environmental Impact Statement. Hydroelectric Power for Sitka, Petersburg/Wrangell, and Ketchikan, Alaska. U.S. Forest Service. June 8, 1993. Comment Letter in regard to Preliminary Permit. Mahoney Lake Hydroelectric Project August 1994 42 FERC No. 11393 Final Consultation Document 9.0 CONSULTATION DOCUMENT MAILING LIST U.S. Army Corps of Engineers Mr. David Rittenhouse Alaska District Office U. S. Forest Service P.O. Box 898 Federal Building Anchorage, AK 99506-0898 Ketchikan, AK 99901 Ms. Tamra Faris Mr. Gary Laver Supervisor-Protected Resources U.S. Forest Service Management Division Federal Building National Marine Fisheries Service Ketchikan, AK 99901 Alaska Region P.O. Box 21668 Mr. Don Ranne Juneau, AK 99602-1668 U.S. Forest Service Federal Building Nevin Holmberg Ketchikan, AK 99901 U.S. Fish & Wildlife Service 3000 Vintage Blvd. Ms. Marlene Finley Suite 201 U.S. Forest Service Juneau, AK 99801 3031 Tongass Ave. Ketchikan, AK 99901 National Park Service Alaska Region Mr. Jack Gustafson 2825 Gamble Street Alaska Department of Fish and Game Anchorage, AK 99503 Habitat Division 2030 Sealevel Drive U.S. Environmental Protection Agency Room 205 Region X Ketchikan, AK 99901 1200 Sixth Avenue Seattle, WA 98101 Mr. Steve Hoffman Alaska Department of Fish and Game U.S. Forest Service Habitat Division Region 10: Alaska Region 2030 Sealevel Drive Box 21628 Room 207 Juneau, AK 99802-1628 Ketchikan, AK 99901 Linn Shipley Mr. Frank Rue, Director Ketchikan District Ranger Alaska Department of Fish and Game U.S. Forest Service Habitat Division 3031 Tongass Avenue P.O. Box 25526 Ketchikan, AK 99901 Juneau, AK 99802-5526 Mahoney Lake Hydroelectric Project August 1994 43 FERC No. 11393 Ms. Christine Valentine Alaska Office of Management and Budget Division of Governmental Coordination P.O. Box 110030 431 N. Franklin Juneau, AK 99811-0030 Ms. Joan Hughes Alaska Department of Environmental Conservation 410 Willoughby Avenue, Suite 105 Juneau, AK 99801 Mr. Tom Stevenson Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Mr. Rich Trimble Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Ms. Bridget Stearns Ketchikan Public Library 629 Dock St. Ketchikan, AK 99901 The Honorable Alaire Stanton Mayor, City of Ketchikan 334 Front Street Ketchikan, AK 99901 Mr. Jack Pearson City Manager City of Ketchikan 334 Front Street Ketchikan, AK 99901 Governor Walter Hickel State of Alaska P.O. Box 110001 Juneau, AK 99811-0001 August 1994 Final Consultation Document Mr. Dick Emerman Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue Suite 220 Anchorage, AK 99501-2341 Mr. Edgar Blatchford Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue Suite 220 Anchorage, AK 99501-2341 Mr. Riley Snell Alaska Industrial Development Agency 480 W. Tudor Anchorage, AK 99503 Ms. Judith Bittner Alaska Department of Natural Resources State Historic Preservation Office P.O. Box 107001 Anchorage, AK 99510-7001 Mr. John Dunker Alaska Department of Natural Resources/Water 400 Willoughby Avenue Juneau, AK 99801-1796 Department of the Interior Office of Environmental Affairs Anchorage Regional Office 1689 C Street, Room 119 Anchorage, AK 99501-5126 Federal Emergency Management Agency Region 10: Bothell Federal Regional Center 130 228th Street, SW Bothell, WA 98021-9796 Mahoney Lake Hydroelectric Project FERC No. 11393 Mr. Bill Geary Alaska Department of Natural Resources Parks & Outdoor Recreation 400 Willoughby Avenue Juneau, AK 99801-1796 Mr. Arthur Martin Regional Office Federal Energy Regulatory Commission 1120 SW Sth Avenue, Suite 1340 Portland, OR 97204 Ms. Lois Cashell Federal Energy Regulatory Commission 825 N. Capitol St. NE Washington, DC 20426 Area Director Bureau of Indian Affairs P.O. Box 3-8000 Juneau, AK 99802 Tongass Conservation Society P.O. Box 3377 Ketchikan, AK 99901 Southeast Alaska Conservation Council 419 Sixth Street, Suite 328 Juneau, AK 99801 Ms. Kate Tessar Alaska Services Group P.O. Box 22754 Juneau, AK 99802 Alaska Environmental Lobby P.O. Box 22151 Juneau, AK 99802 Alaska Public Utilities Commission 1016 W. Sixth Avenue, Suite 400 Anchorage, AK 99501 August 1994 45 Final Consultation Document Mr. Jim Carlton Mayor, Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Mike Rody Borough Manager Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Gary Munsterman Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Jim Boetberg Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Ms. Phyllis Yelte Assembly Member Ketchikan Gateway Borough Box 958 Ward Cove, AK 99901 Mr. Bob Martin, Director Tlingit-Haida Regional Electrification Authority P.O. Box 210149 Auke Bay, AK 99821 Ms. Mary Klugherz McDowell Group 320 Dock St., #201 Ketchikan, AK 99901 City Administrator City of Saxman Route 2, Box 1 Ketchikan, AK 99901 Mahoney Lake Hydroelectric Project FERC No. 11393 Mr. Doug Campbell Cape Fox Corporation P.O. Box 8558 Ketchikan, AK 99901 Mr. Jack Snyder Senior Project Manager HDR Engineering, Inc. P.O. Box 91201 Bellevue, WA 98009 Mr. John Braislin ; Betts, Patterson & Mines 800 Financial Center 1215 Fourth Avenue Seattle, WA 98161-1000 Mr. Don Clarke Wilkinson, Barker, Knauer & Quinn 1735 New York Ave NW Washington, DC 20006 August 1994 Final Consultation Document Mahoney Lake Hydroelectric Project FERC No. 11393 APPENDIX A ALTERNATIVE PROJECT CONFIGURATION DISCUSSION Final Consultation Document APPENDIX A ALTERNATIVE PROJECT CONFIGURATION DISCUSSION WATER CONVEYANCE Two alternative water conveyance configurations, in addition to that proposed for the Project, were evaluated. Those alternatives were: Alternative 1: Construct a low-height dam at the outlet to Upper Mahoney Lake to divert flow into a pipeline all the way to the powerhouse. Alternative 2: Construct the same low-height dam as in Alternative 1, except convey flow to the powerhouse through a 500-foot long buried pipeline, 1,370-foot vertical shaft and 3,300 foot long pipeline placed in an 8-foot wide by 8-foot high horseshoe-shaped tunnel. Average annual energy and construction costs were also developed for these alternative arrangements. Alternative 1 Alternative 1 avoids the use of a tunnel concept completely and instead uses a combination of buried and surface pipeline to move water from Upper Mahoney Lake to Lower Mahoney Lake. A small concrete faced rockfill dam, about 10 feet high would be constructed at the upper lake outlet. A 32-inch pipeline would extend through the dam foundation out into the lake and would serve as the submerged intake. The pipeline would extend downstream from the dam about 500 feet along the creek where it would turn to the right and then drop down the steep rock slope to the proposed powerhouse location. The powerhouse and turbine arrangement are the same as in the proposed alignment, a single 9.6 MW multi-jet pelton turbine, but it would be located in an insulated metal building about 40 ft. by 50 ft. in size. Access roads and transmission facilities would be the same as the selected alternative. This alternative would operate strictly as a run-of-river facility, that is the diverted flow to the turbine would equal inflow to the lake, and the lake level would be generally held constant. A few feet of drawdown might be usable for daily peaking. The positive aspect of run-of-river operation is that there is minimal environmental impact since the lake is at constant levels at all times. After study, this alternative was rejected for two main reasons; 1) the pipeline route is very steep and would have to pass through a rockslide and snow avalanche-susceptible area making construction and maintenance of an above-ground pipeline Mahoney Lake Hydroelectric Project August 1994 A-1 FERC No. 11393 Final Consultation Document almost impossible; and 2) the operating mode of this Project, run-of-river, was much less beneficial to the local utility in meeting the power and energy needs of the region. Alternative 2 In place of the upper tunnel and lake tap in the proposed Project, consideration was given to constructing a low height dam about 500 feet downstream from Upper Mahoney Lake. In this arrangement Project operation would also be strictly run-of-river. Any dam constructed on the stream will be susceptible to damage by rockslide or avalanche, particularly from the steep right abutment. For this reason, the minimum size structure necessary to divert streamflow into the intake was selected. The dam would consist of a grouted gabion structure with an upstream steel plate impervious barrier. The dam would be about 20 feet high and be designed to withstand overtopping flows. The spillway crest would be located 3 feet above the normal maximum water surface elevation to provide a small amount of flood control storage, about 220 acre-feet. Streamflow would be diverted into a concrete and rock- walled intake structure located in the right abutment. A motor-operated 36-inch butterfly valve would be located in an underground vault on the right bank immediately downstream of the dam. A 32-inch buried steel pipeline would convey diverted streamflow a distance of 450 feet to the vertical shaft. The shaft location would not change with the lake tap or dam alternative. The primary disadvantages of the dam alternative include investment in a structure that has a high risk of partial or total damage at some time during its economic life, and the inability of this arrangement to supply firm energy due to the lack of storage and run-of-river operation. A higher dam could be constructed to provide storage, but this increases the potential economic loss in the event of a rockslide or avalanche event. By constructing the minimum height dam necessary, the potential economic loss due to replacement costs and lost generation is minimized. Considerable rock excavation would be required to construct the 450-foot pipeline from the dam to the shaft. Construction cost estimates and energy generation estimates for this alternative were prepared and showed that the run-of-river operating mode of this alternative reduced its cost effectiveness considerably. An alternative to the partially concrete lined tunnels and vertical shaft would be to install a 32-inch steel pipeline in the upper tunnel and vertical shaft, placing the pipeline on saddles in the upper tunnel and backfilling the annular space in the vertical shaft with concrete.. This is considered an overly conservative approach at this time, adding significantly to the construction cost. Based on preliminary geologic studies, it does not appear warranted to assume the water conveyance system will require containment within a steel pipe for its entire length. Until further studies and field investigations are performed, it was assumed that half the length of the upper tunnel and the shaft would require concrete lining, and the lower tunnel would require a small amount of shotcrete protection. Mahoney Lake Hydroelectric Project August 1994 A-2 FERC No. 11393 Final Consultation Document TRANSMISSION LINE ROUTING An alternative to the proposed transmission line route would be to interconnect with KPU’s Beaver Falls Project. This route would be about 1.5 miles shorter in total length than the proposed route. However, to construct along this alternative route would be more costly due to more steep and difficult terrain and it would require a new road along the entire route. In addition, reconductoring of the entire line between Beaver Falls and Ketchikan could be necessary to handle the Mahoney Lake output, according to previous studies. The proposed transmission line will be constructed along an existing road on lands owned by the Cape Fox Corporation, and would only require construction of about one mile of new road. Mahoney Lake Hydroelectric Project August 1994 A-3 FERC No. 11393 APPENDIX B 1982 U.S. FISH AND WILDLIFE SERVICE COORDINATION ACT REPORT United States Department of the Interior FISH AND WILDLIFE SERVICE IN REPLY REFER TO: : 1011 E. TUDOR RD. ANCHORAGE, ALASKA 99503 (907) 276-3800 9.3 wow 1982 Colonel Neil E.. Saling District Engineer, Alaska District Corps of Engineers P.O. Box 7002 : Re: © Coordination Act Report Anchorage, Alaska 99510 Mahoney Lakes Small Hydropower Dear Colonel Saling: This letter transmits the attached Coordination Act (CA) Report prepared under the authority of the Fish and Wildlife Coordination Act (48 Stat. 401 as amended: 16 U.S.C., 661 et seq.) for the proposed hydroelectric develop- ment on Mahoney Lakes at Ketchikan, Alaska. We support the Corps' basic preferred alternative hydropower development plan. However, we recommend that measures to mitigate adverse effects to fish and wildlife resources, as outlined in the attached CA Report, be incorporated into the development plan. The report has been coordinated with Alaska Department of Fish and Game and National Marine Fisheries Service, however, their comments were not received in time for incorporation. We will forward these comments upon receipt. We appreciate the opportunity to comment and advise on matters regarding fish and wildlife resources associated with the proposed hydropower deve lop- ment plan. Sincerely, EK Bg Spe “ene Regional Director Enclosure as stated cc: ADF&G, Juneau, Ketchikan USFS, Sitka FWS, ROES, Juneau, Ketchikan FWS, Federal Projects, WDC NMFS, Juneau MAHONEY LAKES PROPOSED SMALL HYDROPOWER DEVELOPMENT COORDINATION ACT REPORT - Prepared By / Charles E. Osborn, Fish. and Wildlife Biologist Ketchikan Substation Southeast Alaska Ecological Services - U.S. Fish and Wildlife Service Juneau, Alaska November 1982 , EIS-C-2 ~ Is) Introduction < (..:) . . « II. Area Description. .. .- III. Project Description. . IV. Methods - General . ... A. Terrestrial Study - TABLE OF CONTENTS Methods. «2... Cover Types... 2... Species. Selection Field Sampling. .-. Results .. oe B. Aquatic Study. ... Cover Typies. . Species Selection. Field Sampling. . Results -—s:~-<- 6% Discussion and Reconmendations Literature Cited. ..... Glossary FTS-C-3 an a Tn Ww WwW LD 10 17 17 7 18 19 21. 26 Table I. Table I Table I Table: I Ts Il. V. Table V. Figure F igure Figure Figure Figure Appendix A. Appendix B. TABLES . Species list - Acreages and conditions of terrestrial cover types on * “the target years. HSI and HU for each species in each target. year AAHU and HU change: during the 50-year life of the project and during the 275-year baseline-to-recovery life of the project Fish census in Mahoney Creek, Falls Creek, and South Creek 7/16-10/31/81 FIGURES Location of the Mahoney Lake System on Revilla Island : Symbolistic layout of project — Map of study area, durect impact area, and cover types at Mahoney Lake Map of Falls Creek - 4/81 Map of Falls Creek - 8/81 APPENDICES Determination of photo scale. Models used 1. There is some distortion of these maps due to elevation differences at the study site. See Appendix A for explanation. , EIS-C-4 Mahoney Lake Coordination Report : -1- I. Introduction Mahoney Lakes ‘is one of three Ketchikan area potential hydroelectric power projects. A preliminary feasibility study was done (Retherford et al., 1976) in April 1977. The Army Corps of Engineers (COE) requested U.S. Fish and Wildlife Service (FWS). assess the impact of such a project on fish and wildlife in the system. A preliminary Coordination Act Report was completed in September 1977 and concluded that the major losses due to the power project would be of salmon spawning and rearing areas at the base of Falls Creek. Mitigation at that time suggested returning water to the creek near the base of the falls or building a spawning channel with a controlled flow. In March 1979 a final Coordination Act Report was completed which used Habitat Evaluation Procedures (HEP) to document the impacts of the proposed project on fish and wildlife (USFWS, 1979) 1/ In that report it was suggested that the COE acquire lands for rehabitation to compensate for losses in wildlife habitat. In May of 1980, the COE requested that. the HEP. study at. Mahoney Lakes be reconsidered with particular attention paid to the compensation which . would be required if the project were implemented. In addition, the COE requested a detailed map and quantification of use of lower Falls Creek as spawning and rearing areas. This HEP study was designed to answer those questions. J/ The FWS is currently working to bring an aquatic HEP into full Operation. The aquatic HEP used in this study does not reflect this effort, but rather is the terrestrial methodology used in an aquatic habitat. Mahoney Lake Coordination Report i Ia -2- An interagency team including Charles Osborn, FWS, Richard Guteleber | and Harlin LeGare, COE, and Don Cornelius, Alaska Department of Fish and Game (ADF&G), was assembled to review and direct the study. The team met during an April 1981 field session ¥0 out line the Mahoney Lakes study. At this time the species chosen for. evaluation were approved and the levels of HEP for terrestrial and aquatic species were decided. Since then, the members have been kept informed of the progress of the study and consulted as necessary in their particular fields of expertise. Il. Area Description The Mahoney Lakes system consists of connected lakes located in the southern portion of Revillagigedo IsTand (Fig. 1). The upper lake lies approximately 6 miles northeast of Ketchikan at an elevation of near 1,950 feet. The upper lake discharge drops approximately 1,900 feet: in slight ly over 1 mile before entering the Jower lake. Discharge from the lower lake travels almost three-tenths mile before entering George Inlet at a point 16 miles by water from Ketchikan. The watershed extends from Mahoney Mountain, an alpine area at 3,335 feet maximum elevation, down ‘through ‘dense rain forest to sea level. Topographical relief between the upper and lower lakes is extreme and rock cliffs, avalanche chutes, and earth slides are common. A spectacular falls between the upper lake and lower lake is.a landmark to the area. EIS-C-6 Manoney Lake Loordination Keport ; -3- Ill. Project Description The power project (16.5 MW) is designed to take advantage of the nearly 1,900-foot head between the upper and lower lake for generation of . hydroelectric power (Fig. 2). The upper watershed would be dammed with a 25-foot dam for increased water storage. The lake would be tapped at a depth of 225 feet and the discharge would be rerouted through a 36-inch tunnel/penstock to a powerhouse near the lower lake and returned to the natural system in the lower Take. This conduit would be approximately 5,370 feet in length, of which 4,000 feet would be in a tunnel. The electrical power would be transmitted along the coastline of George Inlet 4 miles to Beaver Falls where it would merge with the existing power network. An optional plan considers the selected plan without the dam and third generating unit in the powerhouse. Access for construction and maintenance of the facilities would begin at a seaplane float terminal located on the saltwater adjacent to the lower Take. An access road 1.4 miles in length would service the lower tunnel portal, powerhouse area and the camp area. Helicopter access is now being considered for construction of the dam, upper tunnel portal and the 34.5 KV transmission line. IV. Methods - General Prior to a detailed analysis of this report, the reader should become familiar with the HEP process through the Ecological Services Manuals (Anon., 1980-1981). However, for the casual reader, a brief summary of the HEP process follows. EIS-C-7 Mahoney Lake Coordination Report . -4- HEP is a method which can be used to document the quality and quantity of available habitat for selected wildlife species. The procedure provides information for two general types of comparisons: 1) the relative value of different areas at the same. point in time; and 2) the relative value of the same area at different points in time. Species which are representative of the area wildlife are selected for HEP evaluation, and models are used to estimate the quality of the habitat for those species. The quality value, an index between 0 and 1, is multiplied by the acres of available habitat to determine habitat units. Habitat units are the basic units of comparison among alternatives and through time. A glossary of HEP terms has been provided to aid the reader in understanding the text. (HEP) was used to evaluate the suitability of the Mahoney Lakes area as habitat for several species and to predict the effect the hydropower project would have on those species. A baseline habitat suitability study was accomplished and future suitability was predicted for 4 target years, both with and without hydroproject development. Two levels of HEP were used: moderate level for terrestrial species and low level for aquatic species. Low level HEP was used for aquatic species because the stream which would be most affected by the power plant is evidently too unstable to support a spawning area. This will -be discussed in more detail in the aquatic section of the report. The study area was defined as the watershed of the Mahoney Lakes system plus the transmission line area (Fig. 2). The transmission Tine area extends from the Mahoney Lakes watershed to Beaver Falls and from shoreline to 1.6 miles inland (west). An area was also delineated within the study area which would be more directly impacted by the project. EIS-C-8 Mahoney Lake Coordination Report -5- This direct impact area was defined as one-half mile from roads, transmission lines, camp, power plant, and lakes. However, if the distance to the edge of the watershed is less than one-half mile, then it was considered the limit of direct impact. Habitat unit acreages were derived from the direct impact area. Covertypes were delineated from 1974 U.S. Forest Service color aerial photographs with the aid of a stereoscope. These were later verified in the field on foot and using helicopter reconnaissance. The following covertypes were delineated: alpine/snowfields; steep, subalpine coniferous forest; coniferous forest; muskeg; slide; streamside; lacustrine; riverine; and saltwater aquatic (intertidal). Areas of the covertypes were determined using a Keuffel and Esser Co. Compensating Polar Planimeter, Model 620000. These areas were converted to acres by determining the sea level scale for the flight line and correcting this scale for the mean elevation above sea level of each photo. Sea level scale and mean elevation of the photos were estimated by comparison of the photos with U.S. Geological Survey topographic map, Ketchikan (B-5), Alaska N5515-W13120/15X20, scale 1:63,360. A detailed account of the photo scale determination is in Appendix A. 2/ The use of trade names is for descriptive purposes only and does not imply endoresement by the U.S. Fish and Wildlife Service. ere rn 4 Mahoney Lake Coordination Report 7 ; ; -6- A. Terrestrial Study Covertypes Three covertypes were chosen for evaluat fon of terrestrial species: coniferous forest, muskeg, and intertidal. Slide areas, being devoid of vegetation, were not considered important wildlife habitat. Alpine/snowfields and.steep subalpine forests were not evaluated for two reasons: 1) impact to these areas by the project would be minimal, and 2) the ‘cost of evaluation would be excessive because the areas are inaccessible by foot and investigation would require helicopter support. Species Selection The species used for HEP evaluation were selected by the guilding technique which is recommended in EMS 102 (Anon. 1980-1981). A list of species in the area was made from the Mahoney Lakes Report (Anon. 1979) and is presented in Table I. These species were guilded based on covertype usage for feeding and reproduction, feeding mode, and general niche within a covertype. One species was then selected to represent each cell. Selection was based on hunting or trapping desirability, sensitivity to human influence, niche specificity, and availability of information on species-habitat relationships. The species chosen were black bear, northern bald eagle, blue grouse, Sitka black-tailed deer, and mink. Mahoney Lake Coordination Report -7- Field Sampling Habitat. evaluation using the models entailed measuring variables (such as percent shrub cover), evaluating plotness variables (such as local topographic variation), and determining spacial relationships between covertypes. Measurable variables were measured in the field using transects and quadrats. Plotless variables were estimated from the aerial photographs and ground truthed at the field sample sites. Spacial relationships between covertypes were done with remote sensing as suggested in the HEP Workbook (USFWS, 1981). A random dot grid was superimposed on the covertype map, and distances from-random points within one covertype to another covertype were measured. ~ The terrestrial sampling was conducted in spring and late summer of 1981, April 21-24 and August 18, 19, 24, and 26. Clustered, modified random sampling was used in the coniferous forest to reduce travel time between transects and to better represent the variety of habitat conditions which exist in the coniferous forest. The three cluster locations were chosen where the impact of the power project would be most severe: at the power plant, the camp area, and the transmission corridor. Sample sites were chosen within each area by walking 3 minutes in a randomly selected direction and then establishing a 20 m transect in another randomly selected direction. A total of 10 transects were established in the coniferous forest, four at both the power plant and. camp sites, and two at the transmission corridor site. Modified random sampling was used in the muskeg. As in the coniferous forest, sample sites were chosen by walking 3 minutes in a randomly selected direction and then establishing the transect in another randomly selected direction. There were six transects established in the muskeg. Mahoney Lake Coordination Report 78- A number of measurements were made at each transect. The percent cover of shrub species was measured by dividing the linear distance along the transect covered by a shrub by the length of the transect, and multiplying by 100: % cover = (x meters/20 meters) (100) , where x equals the linear distance covered by the shrub. The-percent cover of ground species was estimated occularly within a 1 x 1/2 m quadrat frame located at 0, 10, and 20 m along the.transect... Tree dominance was measured using the point quarter method at the endpoints of the transects. In addition, the plotless variables were evaluated at each transect site. A detailed description of these methods is contained in Konkel et al. (1980). Plant species were identified according to Viereck and Little (1972). The number of samples necessary was determined for each suitability index (S.I.) at 90% confidence level with 25% relative precision using standard statistical methods (Konkel et al., 1980). Three problems were encountered: 1) there was often a high variance in the S.I.'s because more than one plant species was included in a single S.1.5 2) two different sampling methods (transect and quadrat) were often used because both shrub and ground cover species could be included in some S.I.'s; and 3) a high variance was also encountered because many species have a patchy distribution. In the third instance, increasing the number of test samples increased the variance, thus by the formula in Konkel et al. (1980), more samples were needed for statistical significance. The number of samples determined necessary ranged from 5 to 97 for the different S.I1.'s. Because of the questionable validity of applying the sample size test to S.I.'s and the wide range in number of samples determined necessary, a subjective analysis of the mean, median, and mode of the number of samples necessary for each S.I. for each covertype was EIS-C-12 Mahoney Lake Coordination Report -9- used to select sample size. This resulted in selecting 10 transects and 30 quadrats in the coniferous forest and six transects and eighteen quadrats in the muskeg. The intertidal area was evaluated for one S.I.: percent cover of macrophytes. Since the percent cover which indicated a certain index was within broad limits (see Mink model, App. B), an occular estimate of this variable was made at the proposed dock site. All S.I.'s, Life Requisite: values (LR's), Habitat Suitability Indices (HSI's), Habitat Units (HU's), ana Average Annual Habitat Units (AAHU's) were calculated according to ESM.102 (USFWS, 1980-81) and the individual models. Five target years were chosen for predicting habitat suitability: TYO TY 1, TY 50, TY110, and TY275. Target years 0, 1, and 50 represent the baseline condition, 1 year after the project starts, and the end of the life of the project. HEP mandates that these years be chosen. The 2 additional years were chosen to plot the recovery of the land when the project ends. Target year 110, or the end of the project plus 60 years, is representative of canopy closure condition. Target Year 275, or end of the project plus 225 years, should represent conditicns after tne forest has returned to the old growth condition. Habitat suitability was predicted for both the with and without project conditions for each target year from the baseline data and from Harris and Farr's (1974) account of secondary succession. Acreages of each covertype after project implementation were estimated using information from the Mahoney Lakes Hydropower Project (Anon., 1978) report. AAHU's were determined for the end of the project life, TY50, as well as for the “recovery life of the project", TY275. This was done because, for some species, major FIS=e-79 Mahoney Lake Coordination Report eed) impact of the project will not. occur until canopy closure; and HU's will continue to be lost until the old growth coniferous forest has recovered. B. Results The total study area includes 5,221 acres and the direct impact area includes 2,090 acres (Table Il; Fig. 3). The largest percentage of this area is coniferous forest. The study area also includes broad expanses of alpine/snowfields and:steep subalpine coniferous forest, much of which is not part of the direct impact area. The other covertypes are a small proportion of the study and direct impact areas. Two types of changes would occur to the habitat as a result of the hydropower project: 1) some area would be temporarily lost as animal habitat, and 2) some would be altered. Altered sections were treated as separate covertypes for HSI determination. The transmission line will cut through approximately 4.9 miles of coniferous forest. According to the Mahoney Lakes Hydropower Project Report (Anon., 1978), the corridor will be 75 feet wide with selective cutting beyond that distance to protect the line from danger-trees. The boundary of disturbance was estimated at 100 feet on each side of the alignment (a 200-foot corridor) resulting in a total distirbed area of 119 acres due to the transmission line. Revegetation of the corridor at the project's end should be similar to the recovery of a small logged area, returning to the old growth condition within an estimated 225 years after canopy closure (See blue grouse model, App.-B). As shrubs will remain in the corridor throughout the project life, young conifers should already have become established by the time of project shutdown, and canopy closure may not be long after. cre note Mahoney Lake Coordination Report -11- The road system will also cut through coniferous forest. As proposed, it will be 2 1/3 miles long, 16 feet wide with a 4-foot shoulder, encompassing approximately 7 acres. After usuage is stopped this area should return to the old growth forest. However, it should take longer to revegetate than the transmission line area because the extent of disturbance, such as establishment of the road bed, will have beem much greater. Approximately 14 acres will be covered by the camp, 4 in the muskeg, and 11 in the coniferous forest (difference in area due to rounding). This area will be essentially lost as animal habitat during the life of the project. It is expected that the coniferous forest will return to its original state within the 275-year time period. However, the extent of damage to the muskeg and its recovery route are unknown. The power plant, tailrace, and penstock will cover approximately 8 acres of coniferous forest and eliminate them as wildlife habitat for the duration of the project. It is expected that the construction material of these structures will be long lasting and, therefore, the recovery rate of the coniferous forest in this area is unknown. The dock will cover approximately 0.2 acre of saltwater aquatic, or intertidal, area. This area should rapidly revegetate and return to baseline conditions within a few years of termination of usuage. In addition to direct effects on the habitat, development may result in indirect habitat suitability changes to the other parts of the study area. For example, presence of humans will affect habitat suitability within a half-mile radius of the camp for black bears. Interspersion of covertypes will also change with the development. Mahoney Lake Coordination Report -12- The following information includes species accounts.of model implementation and hydropower project impacts as predicted by HEP. Black Bear The black bear model used: was designed: by Lana Shea (1981) (App. 8). Two covertypes, muskeg and old growth coniferous forest, were evaluated for the baseline condition. Construction of project features would result in loss of some acreage and create an additional covertype, coniferous forest cut, along the transmission line (Table II). After project closure, regrowth coniferous forest would occupy the areas which had been disturbed. Interspersion and aggregation of life requisites are included in the model, but the model does not aggregate covertypes or bears with and without cubs. To facilitate determining AAHU's, a single HSI was determined for the impact area by averaging the HSI's for the with and without cub conditions within each covertype. . These covertype HSI's were then aggregated to a single. number using area weighted averages (ESM 102, Anon, 1980-81). During the life of the project, HU's are lost primarily due to the presence of human garbage and consequent increased bear-human conflict. This problem is eliminated at project's end when the humans move out. The HSI would return to baseline conditions, but a few HU's would be lost to the acres still covered with project artifacts (Table III). However, at TY1i0, canopy closure in the developed areas, including the transmission line and roads, decreases the spring to fall range values (LR, and LRo) and again lowers the HSI. By TY225 , baseline conditions should be essentially restored. Over the 50-year life of the Mahoney Lake Coordination Report : -13- | project, the AAHU's lost are 84 (Table IV). However, if the forest recovery period is included, the AAHU loss is 53. The longer period results in a net loss of over 14,000 HU's as compared with over 4,000 HU's lust during the project's lifetime. Sitka Black-Tailed Deer The model used to determine habitat suitability for Sitka black-tailed deer is a slight modification of the one developed by Lana Shea 3/6/81 (App. B). On the advice of John Schoen, ADF&G, variable Vy> the percent cover of shrubs within x yards, was eliminated. Consequently, the aggregation function for the life requisite spring/summer/fall range, LRys was changed. The covertypes old growth coniferous forest and muskeg were evaluated for baseline condition; and old growth coniferous forest, coniferous forest cut for the transmission line, and muskeg were evaluated for the project life, target years TY] and TY50. After project's termination, regrowth coniferous forest would occupy the coniferous forest sites disturbed by construction (Table II). Snow pack data used was from Beavers Falls (Anon., 1974-1980) for years 1974 to 1980. Winters were classified as high, medium, low or unsuitable or intermediate between two and assigned a SI as specified in Vy of the model (App. B). In the coniferous forest, these SI's were then increased by 0.1 or 0.2 to correct for protection afforded by the canopy. Snow pack SI's in all covertypes were decreased by 0.1 to account for increase in snow pack due to elevation. As directed in the model, aggregation of life requisities were made subjectively. In the coniferous forest, LR, was greater than LRy (winter range). Winter range was considered Mahoney Lake. Coordination Report =~ eae -14- limiting, so the HSI was equal to.LR,. In the muskeg LR, was less than LRo- However, since LRy is probably not limiting in the ecosystem, LR, was chosen as the HSI in the muskeg. The HSI's-for the two covertypes were then aggregated using area weighted means. The effects of project development would be felt by the Sitka black-tailed deer population throughout the life of the project and the recovery time of the coniferous forest (Table III). The loss in HU's during the life of the project is attributable to a decrease in acreage from the powerhouse, camp, and roads. and changes in HSI at the transmission line corridor. In the transmission line corridor, spring/summer/fall range (LR4) would improve in quality, but winter range (LR, ) would decline in quality due to increased snow pack and a decrease in evergreen forbes. During the recovery period, loss in HU's is due primarily to a decrease in HSI of the regrowth areas and secondarily to the small. loss in acreage (12 acres, Table II). From canopy closure (TY110) until recovery of. old growth forest (TY275), both LR, and LR, range would be sub=baseline due ta lack: of appropriate ground cover species. During the life of the project (50 years), 1,782 HU's or 36 AAHU's would be lost; and in the recovery life of the project (275 years) 14,097 HU's or 51 AAHU's would be lost (Table IV). Northern Bald Eagle The northern bald eagle model used (App. 8) is a modification of the one in the Alaska Handbook (Konkel et al., 1980). The coniferous forest type, Vo» was modified to include Alaska yellow cedar and western red cedar, two prominent species in southeastern coastal forests. The ere © LO Mahoney Lake Coordination Report -15- suitability of the distance of an area from shore, Ves was also modified, based on personal communication with Jack Hodges, FWS, and Robards and Hodges (undated). This resulted in three different coniferous forest covertypes: 0-1/8 mile, 1/8-1/4 mile, and greater than 1/4 mile from shore. After project construction, developed coniferous forest would be added as a covertype. The aggregation function for reproduction was also modified to reflect the importance of distance. from shore (App B). “For each covertype, the HSI value was the lowest LR value; and the HSI's for the covertypes were aggregated using an area weighted mean. The HSI's which result from the model, 0.34 to 0.44 (Table III), make the Mahoney Lakes eagle habitat appear less suitable than it actually is. For example, in TYO the area weighted aggregation function combines 292 acres at HSI 0.8 and 296 acres at HSI 0.08 to give 588 acres which have an average HSI of 0.44. The difference between the 2 HSI's is solely the result .of distance from shoreline, Ve: area 0-1/8 mile fron shore having a SI of 1.0, and area from 1/8 to 1/4 mile from shore having a SI of 0.1. Therefore, in reality, there are 292 acres of fairly good habitat and 296 acres of marginal habitat. Although the aggregation of covertypes has no net effect on HU's, the differences in quality should be kept in mind when planning mitigation. Effects of the project on northern bald eagles would be primarily due to not having a 1/8 mile leave strip along the shore (Table III). By TY110 regrowth would improve conditions and by TY275, the area should have recovered as eagle habitat. The loss would be 62 AAHU, or 3118 HU, during the 50-year project life, and 25 AAHU or 7003 HU during the recovery life of the project (Table IV). Mahoney Lake Coordination Report a = -16- Blue Grouse The model used to evaluate habitat suitability for Bi grouse is by Maureen Daly (1981) and was followed without modification (App. 8). In the baseline study, coniferous forest was.evaluated for LR, reproduction, and LR35 winter food; and muskeg was evaluated for LRos late spring/summer/fall food (rearing). After project implementation, coniferous forest that had been converted to roadside and slash was evaluated for LRy and LRo> not LR3. Aggregation of the life requisites is based on interspersion and is included in the model. Blue grouse habitat would be vastly improved during the life of the project because of the increase in area available for rearing (Table III). From the project's end to TY100, the habitat would deteriorate to a level slightly below baseline conditions. By TY275, the blue grouse habitat should return to baseline suitability. The AAHU gained would be 915. (or 45,736 HU) over the 50-year life of the project or 253 (69,631 HU) fie the 275-year recovery life of the project (Table IV). Mink The model for mink in Konkel et al. (1980) was followed without modification. Saltwater aquatic was the only covertype evaluated because: 1) it was assumed that winter habitat (saltwater aquatic) is limiting because of its small area, and 2) the only criterion for. summer habitatis area in shoreline which has an SI of 1.0 in the Mahoney Lakes area. The lowest LR value was chosen as the HSI value for saltwater aquatic, and because only one covertype was evaluated, no further Mahoney Lake Coordination Report Wi a7 aggregation was necessary. Area in shoreline was estimated at 3.7 miles long by an estimated average 15. yards wide, or 21 acres. The only change in habitat from the project would result from a small loss in area due to the docking facility. At project's end, the area lost should quickly revegetate and become suitable for mink. Only 1 AAHU would be lost over the 50- or 275-year time period if the project were implemented (Table III & IV). ° B. Aquatic Study Cover types The Mahoney Lakes study area includes two aquatic covertypes, lacustrine and riverine. There are three streams: Falls Creek, South Creek, and Mahoney Creek; and four lakes: Upper and Lower Mahoney Lakes, and two lakes which drain into Upper Mahoney Lake (Figs. 2 & 3). Species Selection A number of salmonid species are reported from the Mahoney Lakes system. These include: pink, chum, coho, and sockeye salmon, steelhead and searun cutthroat trout, and Dolly Varden char (Anon., 1979). Sockeye salmon was chosen as an evaluation species because of its life history. Sockeye generally spawn in streams which are lake tributaries, or, occasionally, along jake shores. After hatching, the young migrate to the lake were they rear for 1-3 years. The Falls Creek (and South Mahoney Lake Coordination Report ‘ . -18- Creek)/Lower Mahoney Lake configuration meets these requirements. Consequently, the removal of Falls Creek could have an adverse impact on the sockeye salmon run. Dolly Varden was ieee to. represent a species which would use Falls Creek for rearing, as: fry were strapped there in 1977 by the ADF&G. Removing Falls Creek would. result in the loss of this rearing habitat. Field Sampling Fieldwork concentrated on documenting use of the system by salmonids and a HEP study of Falls Creek. Twelve spawning ground counts were conducted between July 16 and October 31, 1981. Only Mahoney Creek was surveyed until the salmon began their upstream migration. After the migration began, Falls Creek and South Creek.were surveyed, and Mahoney Creek was surveyed as time permitted. The HEP study was conducted on the portion of Falls Creek from lower tahoney Lake to the first permanent blockage to upstream migration of salmon. The study was accomplished in two field ries April 22 and 23, 1981 and on August 19, 1981. The creek was evaluated in 60-foot sections. Lengths and widths of the creek were measured with a tape measure to the nearest foot. Gravel size, depth, and bank conditions were then evaluated for each section. Tn addition, the percentages of the area suitable for spawning and rearing were estimated. An area considered suitable for spawning had a cobble bottom with flowing water and was assigned an HSI of 1.0. Areas considered suitable: for rearing were often pools, had undercut banks and tended to be deeper and slower moving than spawning areas. An area which did not meet the requirements ere nan Mahoney Lake Coordination Report -19- for spawning or rearing was assigned an HSI of 0.0. If.any of. the variables changed within the 60-foot section, then the section was subdivided for that variable. During the August evaluation, the first map was used as a baseline, and changes in. the variables were documented and measured. Results It is approximately 1,500 feet from Lower Mahoney lake to the first permanent blockage of salmon migration at Falls Creek (Fig. 4). During the April mapping and HEP evaluation, there were 1.19 acres of stream, of which 30% (0.36 acre) was suitable for spawning and 12% (0.14 acre) was suitable for rearing. Spawning habitat was concentrated between the lake and the second log jam, approximately 775 feet. However, rearing habitat was fairly evenly distributed between lower and upper sections of the stream. During the August HEP study, there was no surface water from the mouth of Falls Creek to 1,000 feet from the mouth (Fig. 5). However, above that point water was flowing and covered.0.26 acre. This dry bed situation was observed on some of the subsequent stream census dates, 8/12, 8/18 and 8/29/81. Even though there were sections of stream where water was flowing that would be suitable for spawning (19%, 0.05 acre) there was no access to them for the fish and HSI equals 0. A small portion, 2% (.007 acre), of this part.of the stream was suitable for rearing. The 1981 salmon run was late, presumably due to dry weather. The fish were observed in small schools just offshore and in the mouth of Mahoney Lake Coordination Report - : - oa -20- Mahoney Creek from 8/8 to 8/18/81 (Table V).: Pink, sockeye, and chum salmon were running up Mahoney Creek between 8/24 and 9/10/81, with most activity on 9/10/81. No adult fish or carcasses were seen in Falls Creek or South Creek on any of the census dates. However, a few fry (probably Dolly Varden) were observed in the creek 8/12/81, indicating that Falls Creek has some value to stream rearing species. On 14 September. 1982, 200-300 adult anadromous sockeyes were observed spawning along the west shore of Lower Mahoney Lake. This was the first confirmation of anadromous sockeyes spawning in the. lower lake. The highest number occurred near the mouth of Falls Creek. Several hundred additional sockeyes were observed moving up Mahoney Creek on the same date. Streams flowing into and out of Lower Mahoney Lake are not used by sockeyes for spawning. Velocity chutes and falls in Mahoney Creek would prevent fry from reaching the lower. lake to rear. Falls Creek is not used, and sections of the streambed are often dry. Much of the flow in Falis Creek travels underground through highly permeable alluvial gravels and enters Lower Mahoney Lake below its surface in the form of upwelling. Where suitable gravels are present, areas of upwelling provide critical spawning habitat for sockeyes. The spawning impulse and proper development of eggs is dependent on water temperatures and currents at points of upwelling. A minimum temperature of 6°C is necessary for proper initial development of sockeye eggs. Vv. Discussion and Recommendations The direct impacts of a Mahoney Lakes power project would be primarily the loss and alteration of some wildlife habitat. cre nm on Mahoney Lake Coordination Report . . -21- Approximately 30 acres of coniferous forest, muskeg and saltwater aquatic covertypes would be temporarily lost as habitat beginning with the project. construction. An additional 119 acres of coniferous forest would be altered by the project. From the project closure to recovery, °137 acres would be in an altered state and 12 in unknown condition. In the aquatic habitat, the diversion of Falls Creek would result in a loss of as much as 0.14 acre of rearing habitat and, without mitigation, the loss of the spawning habitat. The loss of the falls would also be an aesthetic loss to the area. There would also be indirect impacts to a much broader area due to human presence. Increased human/bear contact, for instance, often results in killing nuisance bears. To minimize this impact we recommend that garbage be carefully stored and disposed of in order to avoid attracting nuisance bears. Even though wolves were not evaluated, it should be noted that they may. abandon cubs or den sites when humans move into their territory (Konkel et al., 1980). During the time from project commencement to coniferous forest recovery, a total of 35,718 AAHU would be lost by black: bear, Sitka black-tailed deer, eagle, and mink. In contrast, 69,631 AAHU would be gained by blue grouse. The major reason northern bald eagle lost HU's is that the proposed transmission line falls within 1/8 mile of shore. Moving the line back to 1/8 to 1/4 mile from shore slightly reduces the HSI in TY] and TY50 (as compared with the baseline HSI); and during TY110 and TY275, the HSI would be equal to baseline conditions. This results in the reduction of AAHU loss from -62 to -12 over 50 years or from -25 to -4 over 275 years. Therefore, it is suggested that a power line further than 1/8 Mahoney Lake Coordination Report ml >i -22- mile from shore be considered. Although no eagle nests were found in the 4-mile shoreline from Mahoney Lakes to Beaver Falls, the potential for nesting would be greatly reduced if the power line were located as presently planned. Another concern regarding bald eagles -and other raptors is potential mortality due to electrocution and/or entanglement. We recommend that the powerlines be designed and constructed in such a manner as to avoid this potential problem area. Design criteria should be patternea after those illustrated and discussed in Olendorff et al. (1981). A dam at the outlet of Upper Mahoney Lake would eliminate flows in Falls Creek. This, in turn, would disrupt upwelling processes along the west shore of the lower Take. Sockeyes that spawn in this area would be adversely affected. In the current project proposal, the powerhouse would be located near the west shore of Lower Mahoney Lake. To mitigate the disruption of upwelling processes, tailrace waters should be directed into the braided channels of Falls Creek as far above the lower lake as possible. This would simulate preproject intra-gravel flows to points of upwelling along the west shore of Lower Mahoney Lake. Water taken from the bottom of Upper Mahoney Lake and discharged from the powerhouse into the lower lake would be about 4°C year-round. While temperatures in the lower lake as a whole are ‘not expected to change sig- nificantly, local temperature changes along the west shore of the lake would occur. Negative impacts associated with discharge of colder water to points of upwelling between September and early November include alteration of sockeye spawning behavior and improper initial development of eggs. Mahoney Lake Coordination Report -23- Another consideration is the effect of 4°C water on the total incuba- tion and fry development time frame. If eggs survive the initial shock of colder water, development would proceed at a slower rate than under . normal conditions during the fall and early winter: However, by mid- winter the 4°C discharges would be slightly warmer than normal, whereby development of eggs may be accelerated. If fry emerge into the lower lake earjier or later than normal, food supplies may be inadequate. To mitigate the impacts of colder water on spawning behavior and early development of eggs, three options could be considered: 1) con- struction of a multilevel or floating intake structure in the upper lake; 2) pumping water from the lower lake into the tailrace; and 3) creation of an artificial spawning channel. We understand there are some severe technical constraints associated with item 1 above. We would, therefore, recommend that pump(s) be installed in the lower lake to moderate water temperatures: in the tailrace. Indications are that the pump(s) would only operate during a period in the fall (September and October), and again in late winter (February and March). The exact schedule of pump operation would have to be formulated as a result of a monitoring program. We would, therefore, concurrently recommend that a monitoring study be designed and incorporated into the project plans whereby adverse and or beneficial impacts to sockeye salmon would be evaluated and a pump operation schedule would be devised. Study participants would include representatives of the COE, FWS, National Marine Fisheries Service (NMFS) and ADF&G. At an agreed upon time the study participants would evaluate the success of the mitigation measure and recommend necessary changes. Mahoney Lake Coordination Report . EE -24- Recommendations To provide mitiaation for project associated adverse impacts, the FWS recommends the following: T. All human garbage should be carefully stored and disposed of. The transmission line location should -be located more than 1/8 mile from shore. The transmission line be designed and constructed to avoid potential raptor mortality caused by electrocution and/or entan- glement. See Olendorff et al., 1981. Water from the powerhouse tailrace should be returned to the streambed as far above the lower lake as practicable. The use ” of pumps to accomplish this measure should be investigated. Pump(s) be installed in the lower lake, capable of supplying a sufficient quantity of water to maintain preproject thermal conditions. A monitoring program be established concurrent with project development to assess project impacts on sockeye salmon and devise a pump operation schedule. This program would provide the data base in determining whether or not additional mitigation and/or alternative mitigation measures are Mahoney Lake Coordination Report . -25- necessary. Alternatives which could be considered would include an artificial Spawning Channel.. The COE, FWS, ADF&G, and NMFS would be the primary participants in the design and implementation of this study. Mahoney Lake Coordination Report : -26- Literature Cited U.S. Fish and Wildlife Service, 1981. Habitat Evaluation Procedures Workbook. HEP Group, ; atl Western Energy & Land Use Team, U.S.: Fish & Wildlife Service. Drake Creekside Building, 2625 Redwing Road, Fort Collins, CO 80526 U.S. Fish and Wildlife Service, 1980-81. Ecological Services Manual Habitat Evaluation Procedures. ESM 100-104. Division of Ecological Services, Fish and Wildlife Service, Dept. of the Interior. Anon., 1979. Mahoney Lakes Hydropower Project. United States Dept. of the Interior, U.S. Fish & Wildlife Service, Anchorage, Alaska. 21 pp. Anon., 1978. Mahoney Lakes Hydropower Project. Anon., 1974-80. Climatological Data. Vol. 60-66. U.S. Dept. of Commerce, National Oceanic & Atmospheric Administration. Environmental Data Section. Asheville, D.C. Combs, B. D. 1965. Effect of temperature on the development of salmon eggs. Progressive Fish Cult. 27(3): 134-137. Harris, A. S. & W. A. Farr. 1974. The forest ecosystem of southeast Aliaska 7. Forest Ecology and Timber Management. USDA FS General Technical Report PNW-25. Pacific Northwest Forest and Range Experiment Station, U.S. Dept. of Agriculture, Forest Service, P.O. Box 3141, Portland, OR. Konkel, G. W., et al. Terrestrial Habitat Evaluation Criteria Handbook - Alaska. Div. of Ecological Services, U.S. Fish & Wildlife Service, Anchorage, Alaska. Olendorf, R. R., A. D. Miller, R. N. Lehman. 1981. Suggested Practices for Raptor Protection on Power Lines - The State of the Art in 1981. Raptor Research Foundation. Department. of Veterinary Biology, University of Minnesota, St. Paul, Minnesota. Retherford, R. W. Assoc., K. Miller, Bentheimer Engineering Co., Inc. 1976. Ketchikan Public Utilities Comprehensive Study. Electric, water and telephone divisions. Robards, R. C. and J. I. Hodges. Undated. Observations from 2,760 bald eagle nests in southeast Alaska. Progress Report 1969-1976. Department of the Interior. U.S. Fish & Wildlife Service, Eagle Management Studies, Juneau, Alaska. Viereck, L. A. and E. L. Little. 1972. Alaska trees and shrubs. Agriculture Handbook No. 410. Forest Service, U.S. Department of Agriculture, Washington, D.C. EIS-C€-30 Glossary of HEP terms Aggregation function - the methematical function. which combines SI's to an LR value, LR values to a cover type | HSI, or cover type HSI to a single HSI Average Annual Habitat Units (AAHU) - the number of HU: lost ‘or gained over the life of a project on an annual basis as a result of a given action Cover type - a habitat type which can be defined by. a set of vegetational or physical parameters; i.e. coniferous forest, cold small lake Habitat Evaluation Procedures (HEP) - a species based method of determining impacts of development to habitat; may be used to compare alternatives, predict impact, and quantify mitigation necessary Habitat Suitability Index (HSI) - an index between 0 and 1 which Tepresents the quality of a habitat for a given species; the HSI may be for a single cover type or a number of cover types which meet the needs of a species Habitat Units ‘(HU) - an abstract value related to the number of wildlife individuals a habitat can support; it is determined by the formula HJ = HSI x acres Life Requisite (LR) - a need of a species such as food, cover, or reproduction Life Requisite value (LR; ) - an index between O and 1 which represents the capacity of a given habitat to support a life requisite of a species; one or more SI determines a LRy Suitability Index (SI) - an index between 0 and 1:which represents the quality of a cover type variable in relation to a species' needs Target year (TY) - a year in the life of the project for which the habitat is evaluated : EIS-C-31 Table I Species List (from Mahoney Lakes Report, March, 1979) Mammals Fish - black bear Sitka black-tailed deer wolf beaver river otter mink martin shrews pink. salmon chum salmon coha salmon sockeye salmon steelhead trout sea-run cutthroat trout Dolly Varden char voles red squirrel weasel Birds northern bald eagles blue grouse ptarmigan ruffed grouse spruce grouse plus a variety of marine winter residents, migrating . ducks, shorebirds, and seabirds EIS-€-32 Table II. Acreages and condition of Cover type Alpine, snowfields Coniferous forest steep, subalpine Coniferous forest old growth transmission line road plant camp regrowth condition unknown Muskeg unaltered camp condition unknown Saltwater aquatic unaltered dock Slide Riparian Lacustrine Total not evaluated Acres In Study Area 21 58 25 256 5221 Tye - 24 222 3090 Acres in Direct Impact Area. Tyl ! aiile Lo Lite) ht EIS-C-33 TYSO TY110 terrestrial cover types on the target years Table III. HSI°and WJ for each species in each target year Target. year Species 0. 1. 50 110 275 Black bear HSI 0.83: 0.76 0.83 0.79. 0.83 ° HJ 1453 1309.. 1425 ..1381 1444 Sitka black- . _ . tailed deer HSI 0.62 0.61 £O.61° 0.57 0.62 HJ 1086 1055 1055. . 995 1079 N. bald eagle HSI 0.44 0.34 0.34 0.41 0.44 HU 259 196 196 241 259 Blue grouse HSI 0.48 1.0 1.0 0.47 0.44 HJ 840 1729 1729 818 835 Mink HSI 0.93 0.93 0.93 0.93 0.93 HU 20 19 19 20 20 Table IV. AAHU and HU change during the (50 year) life of the project and during the baseline-to-recovery (275 year) life of the project AAHU AAHU Species TYO - TYSO Total # HU's TYO- -TY275 Total # HU's Black bear : -84 4188 -53 14343 Sitka black-tailed deer -36 1782 : -5l : 14097 Northern bald eagle -62 : 3118 -25 7003 Blue grouse +915 _ 45736 - . +253 69631 Mink -1 50 : ~1 275 EIS-C-35 Table V. Fish Census in Maton a ‘Falls Creek, and South Creek ; 7/16-10/31/81 Number of each species Date ‘Mahoney’ Creek Falls Creek © South Creek 7/16/81 : 0 cy = 7/22/81 0 - - 7/28/81 oo = — 8/8/81 100 = BRO aye = 7 8/12/81 Og OM 0 0 -water too milky 8/18/81 ? = but fish seen 9 9 jumping rs 8/24/81 2¢ serkeve = = 8/29/81 §9 BitKeye 0 0 9/10/81 pokeye 0 0 183 889 pL Aks 9/24/81 0 0 10/14/81 0. 0 10/31/81 ~ ee 0 ETC=eC=36 Project Map | a oo cf | MAHONEY LAKES PROJECT EIS-C-38 => ‘y 7 . N.. 7 N ¢ \ 7 No 7 NS 7 » ! \ “NS Falls \ Cre \ N \ NK ji ; SAL unne ~S . se \ ‘ \ > \ \ cP efistock \ auf Powerhouse \ ae x Tailrace t Road i \ \ \- South Teek 1 | ! { a i Creek Direct impact 7 . 4 ie | area boundary, 1 7 J . \, . f Dock co Powerline,” 7 \V- 7 aS --" . - Y , 7 7 7 7 - 4 at cs a = Figure a ETS-C-39 ae Lake Alpine/snowfield Steep,subalpine coniferous fores Coniferous fores Muskeg Slide Streamside Direct impact ar Ob-I-SI13 pees ura sacs yon pene a as-s Gp 3 7 ‘ : S4D0TwaYy 5 | Bunok-yueq | i ; ui-2 2 vis bHtod ue was ‘@]Qut sua f 5 { . Lappy ete ayia th uw ! 1 . uss of eee SPoTwey ‘ : x ' MOT ~ eG ° 1 ‘. xtw pene ya tauptneg | fy ulna us 1 ste ot t ' i 1 ura ds Staqgup ~ = eae faqup -q7uRg : i sayem : 1 ity fs2ap i (Hog soaK] ‘ ' ' 1 ! N ‘, \ g74 i ues zee bes N= 180q Pree pune Noon oT = yuRg rg 1 a i Tie us «(NU u-s Y ate} i : j S pall 8p (NOG 27 ! ‘i awptncg sbsey “-P ) J 7 \ a i * 4 . ~ ° “2 gigses6 ’ Sé-s t o-P 1 “3 S ie oes | ~thnes 0z-p ! 1 Te0d 2-1 ' etssTs 9-2 ; -janei6 1 noe Gs-8 \ s-P i y Qn-3 : Ors + | a, 8-p | oc-s = op i Qnzys AoT | yuk staigap j =nHeq 6-s . ' | ! | ' ' -—_———____ ~ , eS ~Nc ss gc r 1 Stier road ano Se a a ee a a ane . SO k& UGK ‘Vaya > mk . SOW Pa 7 a XN or 4 \ EIS-C-41 Fig. 4 and Fig. 5 Key: water boundary —--- gravel boundary bei : Ju 44 undereut bank © log jam .12-61 size of rock in section.of stream (inches) p-22 pool - depth (inches) d-5 depth of stream - inches s-15 % of anaes suitable for spawning r-10 % of section suitable for rearing Scale: 1" = 60' EIS-C-42 a et a me IO STN mS eet Se \ €v-9-S14 Key - App.A - Fig. 1 1 Coniferous forest 2 Muskeg 3 Slide 4 Steep, subalpine forest 5 Alpine, snowfields 6 Streamside 7 Intertidal (saltwater aquatic) 8 Lacustrine ----- photo boundaries +-.-. boundary of direct impact area APPENDIX C AGENCY CORRESPONDENCE Final Consultation Document APPENDIX C AGENCY CORRESPONDENCE Listed below in chronological order is the agency consultation that has been conducted to date for the Mahoney Lake Hydroelectric Project. All of the referenced letters, documents, and meeting notes are attached. = Fish & wildlife data 6-77 12-18-77 USFS USFWS FERC 1-23-78 Planning aid comments and data Updated power values 3-1-78 2-2-79 5-20-80 | Recommendation for cultural resources | survey | Recommendation for cultural resources | survey ( 5-30-80 USFWS Threatened or Endangered Species List 4-27-82 4-14-82 ADPDP Feasibility Study comments Request for cooperating agency status in EIS development FG 4-82 EPA 3-31-82 USFS 3-31-82 Threatened or Endangered Species List 3-16-82 COE COE COE COE COE COE COE COE COE COE COE USFWS COE FERC 6-8-93 USFS Agencies Initial Consultation Document (ICD) Distributed Submitting request for review and comment of ICD from state agencies Agencies Invitation to 4-26-94 Initial Consultation Meetings Threatened or Endangered Species List | Project Correspondence 3-23-94 Cc Preliminary Permit Comments 3-31-94 ~! 4-1-94 4-8-94 Gov. Hickel Unable to attend 4-26-94 Meetings ICD Comments Response to 4-1-94 letter Mahoney Lake Hydroelectric Project August 1994 C-1 FERC No. 11393 4-13-94 4-15-94 Final Consultation Document 4-15-94 Ketchikan Daily News Affidavit from public notice for 4-26- 94 meetings 5-4-94 Scientific collecting permit application Audio tape recordings of 4-26-94 | 4-26-94 Meeting Minutes ICD Comments ICD Comments Northern goshawk nest site info ICD Comments NMEFS/USFWS/ Threatened, Endangered & Rare Species Request ICD Comments i ICD Comments 1983 COE Draft EIS Threatened & Endangered Species List 1983 COE Cultural Resources Info ICD Comments ICD Comments Threatened & Endangered Species List Response to 6-21-94 comment letter Acronym Definitions: ADFG Alaska Dept. of Fish & Game ADGC Alaska Div. of Governmental Coordination ADNR Alaska Dept. of Natural Resources ADPDP Alaska Div. of Policy Development and Planning ANHP Alaska Natural Heritage Program COE U.S. Army Corps of Engineers ENRI Environmental and Natural Resources Institute FERC Federal Energy Regulatory Commission HDR HDR Engineering, Inc. Ketchikan Gateway Borough KPU Ketchikan Public Utilities NES Northern Ecological Services NMFS National Marine Fisheries Service THREA Tlingit-Haida Regional Electrical Authority USFS U.S. Forest Service USFWS U.S. Fish & Wildlife Service Mahoney Lake Hydroelectric Project August 1994 C2 FERC No. 11393 United States Department of the Interior FISH AND WILDLIFE SERVICE ALASKA AREA OFFICE . 813 D STREET. : ANCHORAGE, ALASKA 99501 ¢ QUN 1977. Colonel George R: Robertson District Engineer Alaska District, Corps of Engineers P, 0. Box 7002 Anchorage, Alaska. 99510 ‘Re: .NPAEN-PR-R Dear Colonel Robertson: : This responds to Mr. D. G. Hendrickson's letter of April 27, 1977, which requested field data and our initial assessment of fish and wildlife impacts which may result. from the proposed Upper Mahoney Lake hydroelectric project near Ketchikan, Alaska. The time constraint of:your draft EIS schedule precluded investigations of the fish and wildlife resources in the Upper Mahoney Lake portion of the system because of ice and-snow cover. We have rescheduled field investigations in the upper lake for early June, 1977, and will modify our comments should the results of that investigation so dictate. Due to the-lack of sufficient quantitative data on the salnion runs in the system, we will conduct follow-up spawning ground - surveys during August through October, 1977. Again, should the results so justify, this initial assessment shall be modified. The project area is used by a variety of fish and wildlife species. The aquatic system is of significant value to fish resources, particularly pink, chum, coho, and sockeye salmon; and Dolly Varden, cutthroat, rainbow, and steelhead trout which use the inlet streams to the lower lake as a spawning ground. Grayling were stocked in the upper Take in the 1950's and would depend on its inlet streams for spawning. Other freshwater fish species include sculpins and sticklebacks. The estuarine system provides life requirements for numerous organisms including both resident species and those which depend on the estuaries at some stage in their life history. Among the estuarine fish resources are.all species of Pacific salmon, the searun varieties of trout, CONSERVE Save Energy and You Serve America! EIS-A-13 Pacific herring, several species of rockfish, several species of flatfish, and cod. Shellfish resources include several species of clams and mussels, several. species of shrimp, and Dungeness -and other crab species. ; Wildlife resources that are closely associated with this estuarine system include waterfowl, seabirds, shorebirds,-and seals. Bald eagles, deer, black bear, grouse, beaver and other furbearers: use substantial portions of the ecosystem, Based on the data ‘available-at this time, the maintenance of spawning and rearing habitat for salmon and trout.in the stream fiowing between Upper Mahoney Lake and Lower.Mahoney Lake iS our primary concern relative to the proposed project. The water discharged from the powerhouse should be returned to the natural stream above the spawning habitat, preferably near the base of the falls. Any overflow from the upper jake should be allowed to follow the existing natural route. A minimum water flow in the natural stream channel during the spawning and incubation periods of. July through March must be maintained. The magnitude of the minimum flow required will be determined after further study. The concept applied, however, is that on a given stream with all else remaining constant, the production of that stream will decrease directly as spawning gravel becomes exposed. The proposed access road will cross inlets to the lower lake. Where this occurs the crossings should be constructed so as to effectively prevent siltation and disturbance of spawning grounds. The four miles of proposed transmission line along George Inlet to Beaver Falls will be traversing an area likely to contain eagle nesting trees. The specific route should be so designed to effectively avoid nest tree disturbance. The results of the Upper Mahoney Lake investigation will determine the status of the grayling stocked there. The presence of grayling- may require further restrictive comments on the proposed project. We appreciate the opportunity to provide comments at this early stage of project planning and to alert you to our primary concerns relative to this project. Sj fae yours, 1 K EIS-A-14 - UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE P.O. Box 1628, Juneau, Alaska - 99802 2360 Lv ie IC Mr. George R. Robertson District Engineer Corps of Engineers. P. 0. Box 7002 Anchorage, Alaska -99510 Dear Mr. Robertson: The following is in reference to NPAEN-PR-R, letter of November 18, requesting preliminary historical/archeological report for three potential hydroelectric sites near Ketchikan, Alaska. a. Lake Grace: No historic/archeological sites are presently known in this vicinity; however, the vicinity of the dock and work cap have a high potential in view of the salmon runs in Grace Creek and the estuarine nature of the mouth of the creek. The inland areas of the transmission line to Carrol] Inlet have low potential. b. Swan Lake: No historic/archeological sites are presently known in the near vicinity of the lake, powerhouse, and transmission line to the point of crossing Carroll Inlet. Potential for historic/archeological materials in these areas is judged to be low. The transmission line from Nigelius Pt. - Shelter Cove - Ward Cove will be in the vicinity of a petroalyph reported in Shelter Cove and a large historic site identified by Sealaska Corporation in Leask .Cove.. The potential for archeological sites along the inland portions of the transmission line is low. c. Mahoney Lake: There is a petroglyph reported in the vicinity of the cove east of Mahoney Lake, and anabandoned mine near the creek mouth. Potential in this area may be considered high. The first half of the transmission route to Beaver has a. medium to low: ‘potential; the second half has a low potential. Or. Robert Ackerman, Department of Anthropology, Washington State University, Pullman, Washington, has conducted a partial archeological survey of the Swan Lake Hydroelectric Project for R. W. Beck and Associates. When this survey is completed, we will be in a position to provide firmer data concerning historic/archeological materials for that portion of the study.area. 6200-11 (1/69) EIS-A-11 2 ‘I hope the above information is°of help. Please do not hesitate to call if your require further assistance. ~ ; ; : ‘Sincerely, ty /) ae : Kront Bh Obata GERALD..H. CLARK — Regional Archeologist EIS-A-12 PR-RCgrarwer<) TR-EN United States Department of. the Interior FISH AND WILDLIFE SERVICE ALASKA AREA OFFICE 813 D STREET ANCHORAGE, ALASKA 99501 . 28 JAN 1978 Colonel George R. Robertson : District Engineer . Alaska District, Corps of Engineers P. 0. Box 7002 _ Anchorage, Alaska.99510 Attention: Environmental Section Re: NPAEN-PR-R Dear Colonel Robertson: This planning aid report. follows our initial assessment of fish and wildlife impacts which may result from the proposed Upper Mahoney Lake hydroelectric project near Ketchikan. Subsequent to our initial response of June 6, 1977, the ice finally cleared on the upper lake allowing biological investigations there. The result of that field trip resolved our concern for the fate of 1966 introductions of grayling into the upper lake. We found no evidence of survival. (Our letter of June 6, 1977, indicated the grayling introduction occurred in the 1950's but was in error). The adequate flow of water through suitable spawning gravel in the transfer of water from the upper lake to the lower lake remains our : primary concern. Since the initial assessment, other conceptual alternatives concerning the disposal of the tailrace waters have developed. This.report summarizes and initially assesses these alternatives. Also, this report includes a summary of the physical and biological data concerning the Mahoney Lakes systems which are now available in our files. The conceptual alternatives for use of the. tailrace waters as we see them are: (1) As was originally proposed, the tailrace waters to be channeled directly into the lower lake. (2) As we originally recommended, the tailrace waters to be returned to the stream near the base of the falls with a minimum flow pattern guaranteed. (The minimum flow required at any given time would CONSERVE AMERICA'S Save Energy and You Serve America! ELS~A-7 e depend on the specific activity, such as spawning, incubation, rearing, etc., taking place at that time and would.vary through the year. This will be referred to as the minimum flow pattern). (3) Same as #2 without minimum flow pattern guarantees. (4) A mitigating alternative which would direct a controlled flow through a spawning channel, then into the original stream channel. (5) Same as #4 except:the discharge would be directed into the lower lake. The use of alternative #1 would effectively eliminate all spawning and rearing within the stream. Thus, greater than 50 percent of salmonid production in the drainage would be curtailed. This alternative appears to be the least acceptable. Alternative #2 should be an acceptable choice provided the magnitude of minimum fiow could be determined and maintained. Further study of the minimum flow pattern required would be necessary. Alternative #3 would likely curtail production.in some years while -not affecting it in other years. The overall impact would ultimately result in a degraded system. This alternative is also among the least desirable. Alternatives #4 and #5, with a controlled flow spawning channel would offer an apparently desirable mitigating feature, provided there was a guaranteed minimum flow pattern incorporated in the artificial channel. Alternative #4 would be highly desirable during times of high flow when sufficient water would be available to utilize the natural stream spawning areas in addition to tne spawning channel. On the other hand, during low flow times there may be insufficient water in the natural streambed to allow fish passage to the controlled spawning channel. Alternative #5 would make spawning gravel available regardless of the flow conditions. Also, as a result of a greater hydraulic head this alternative potentially offers the largest stable production area. Alternative #5, therefore, appears to be the most desirable--its greatest drawback being one of esthetics. : Physical Profile - fisheries oriented Upper Mahoney Lake Lower Mahoney Lake Drainage size 2 mie 50. mic (includes upper lake) Lake surface area 57.5 ac. 160 ac. - (115.2 ac. by Retherford) EIS-A-8 Lake depth Lake volume Surface flow Spawning gravel Water temperature BSiclogical Profile Plankton Aquatic vegetation Invertebrates Fish Native Introduced Upper Mahoney: Lake . 265 ft. (80.8 m:) 5009 acre-feet (Est.) 'A' Intet - 15 cfs 8/4/77 'B' Inlet - 40 cfs 8/4/77 Insignificant 8/3/77 Bir 24°C Surface - 9.0°C Thermocl ine 0 4/5 m - 7.2/6.6°C Some diatoms & others 1977 ; Secchi disc - 30m 1977 No data available 1977 - abundant (including chironomids, stoneflys, diptera, caddis, mayflies. and leeches ) None observed Grayling - 1966 (without apparent success) EIS-A-9 Se Lower Mahoney Lake 220 ft. (67.1 m.) 20,400 acre-feet Qutlet records show a range from 2 cfs to 171 cfs and an average of approx. 40 cfs. “540 m* from base of fais to lower lake. 1060 m total. 4/21/77 Surface - 4.7°C 6m - 4,00C 4.0° C to bottom No data available - however, appears more productive than upper Take. Sparse - ADF&G 1952/70 Present - ADF&G 1952/70 "Insects & larvae, snails and pea clams" All salmon except kings; kokanee, rainbow, steel- head, dolly varden, cut- throat, cottids and stickleback. Eastern brook 1931-32 (without apparent success) An introduction of kokanee was also apparently made. Upper Mahoney Lake © 1977 Observations No ‘fish observed — ; Lower Mahoney Lake Abundant kokanee and dolly varden in Take. Sockeye*, pink, and chum salmon observed jin spawning condition in streams. Dolly varden fry observed in all areas. *Note: Historically, many people : subsistence fished for sockeye salmon. - The system has since been closed to all subsistence fishing. . Other vertebrates Waterbirds, bear, deer and furbearers. Eagles, ducks and other water- birds, grouse, bear, deer and furbearers. We appreciate the opportunity to provide planning aid comments and data. Piease keep us advised as to project status and let us know if we can be of further assistance. Sincere] y yours, EIS-A-10 FEDERAL ENERGY REGULATORY COMMISSION - REGIONAL OFFICE . 555 Battery Street, Room 415 San Francisco, California 94111 March. 1, 1978 Colonel George R. Robertson .; District Engineer Alaska District, Corps of Engineers P. 0. Box 7002 Anchorage, Alaska 99510 Dear Colonel Robertson: In response to your letter of January 30, 1978 (NPAEN-PR-R), we are supplying updated power values for the proposed Lake Grace and Upper Mahoney hydroelectric projects near Ketchikan, Alaska. The at-market values are based on the estimated costs of power from alternative diesel-engine driven generating plants at Ketchikan and Metlakatla. The Ketchikan Public Utility Zkeu) alternative plant con- sists of a 6,450 kW unit with a heat rate of 9,300 Btu/kWh, capital cost of $330 per kilowatt, service life of 35 years, and fuel oi] cost of 42¢/gallon. An interest rate of 8.0% was used for KPU financing. The Metlakatla Power & Light (MPL) alternative plant consists of a 7,500 kW unit with a heat rate of 10,500 Btu/kWh, capital cost of $370 per kilowatt, service life of 35 years, and fuel oi] cost of 44¢/gallon. REA financing at 5.0% interest rate was used for MPL. The values given on the following tables are applicable to both the Lake Grace and Upper Mahoney projects at the appropriate power markets. They are based on January 1, 1978 price levels. As requested, the power values are given for power utilization at Ketchikan only, and for a combined Ketchikan and Metlakatla market. Very truly yours, : —— gen DROS Eugene eblett Acting Regional Engineer Attachment cc: North Pacific Div. Corps of Engineers EIS-A-5 Table 1. Value of Hydroelectric Power at Ketchikan Market Municipal Financing (@ 8.0% interest) _. Capacity — - 49.50 $/kW-yr. Energy 32.60 mills/kWh Federal Financing (@ 6-5/8% interest) Capacity 41.38 $/kW-yr. Energy 32.60 mil1s/kWh Table 2 Value of Hydroelectric Power at Combined Ketchikan and Metlakatla Markets Composite Financing (Municipal @ 8.0% and REA @ 5% interest) Capacity 1/ 47.61 $/kW-yr. Energy 2/ 33.82 mil1s/kWh Federal Financing (@ 6-5/8% interest) Capacity 1/ 42.93 $/kW-yr. Energy 2/ 33.82 mills/kWh 1/ 75% KPU plant capacity value + 25% MPL plant capacity value. 2/ 80% KPU plant energy value + 20% MPL plant energy value. EIS-A-6 , . a “yL 72) ; CM AUS > - ore. f 2 are " JAY S. HAMMOND, GOVERNOR Chip Dennerlein, Director DEPARTMENT OF NATURAL RESOURCES 619 Warehouse Dr., Suite 210 . Anchorage, Alaska 99501 DIVISION OF PARKS _— 274-4676 May 20, 1980 Re: 1130-2-1 Harlan E. Moors |” an Chief, Engineering Division Alaska District, Corps of Engineers - P. 0. Box 7002 Anchorage, Alaska 99510 Subject: Mahoney Lake Hydroelectric Project Dear Mr. Moors: We have reviewed the subject proposal and. would like to offer the following conments: : STATE HISTORIC PRESERVATION OFFICER The proposed hydroelectric project may impact significant cultural “resources. AHRS site KET—017 is located within or very near the proposed Project. No systematic cultural resources survey is known to have been conducted in the ar2a. Therefore, under provisions of 36 CFR800, a preconstruction cultural resources survey is recommended. William S7 fle Sincerely, Gh. GE Nip Dennerlein Director CD/cw O-nVTUt EIS-A-3 O94. 5:97 DEPARTMENT OF NATURAL RESOURCES disfaeeoanneeaceen February 2, 1979 - ; DIVISION OF-PARKS Anchorage, Alaska 99501 Re: 1130-2-1 J. K. Soper, Chief Engineering Division . . Alaska District, Corps of Engineers P.O. Box 7002 : . Anchorage, Alaska .99510 Dear Mr. Soper: This letter is in response to your request of January 29th for our views on the Mahoney Lakes and Lake Grace projects and their involvement with archaeological or historic properties (your. reference NPAEN-PL-EN). Our comments generally parallel those of Dr. Gerald Clark in his letter to your office which you had enclosed. We feel that the Mahoney Lakes area of the camp and access road and the saltwater access area should be archaeologically surveyed prior to any finalization of plans. The power line as Dr. Clark noted appears to be a low potential area; however, we would like to see the documentation of the possible or probable impacts on the fines indicated in your routing sheet.- In the Lake Grace area the power line as Dr. Clark again mentioned is a low probability area; however, the access area and camp area near salt water is very high in potential and we again concur by feeling that an archaeological survey should be done in that area. If you have any further questions, please contact us. Sincerely, LE Wiiliam S. Hanable State Historic Preservation Officer DRipg cc: Dr. Gerald Clark, Regional Archaeologist U.S.D.A. Forest. Service P.O. Box 1628 Juneau, Alaska 99802 EIS-A-4 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE 1011 E. TUDOR RD. Rr IN REPLY REFER TO: SE ANCHORAGE, ALASKA 99503 R71 (907) 276-3800 Colonel Lee R. Nunn District Engineer 3 0 MAY 1980 Alaska District, Corps of Engineers P.O. Box 7002 Anchorage, Alaska 99510 Dear Colonel Nunn: This responds to your May 19, 1980, request for a list of threatened or endangered species which may occur in the following project areas: Location Activity Village of Mekoryuk on Nunivak Island Two breakwaters and revetment Village of Scammon Bay Small hydroelectric project Cordova Interim Southcentral Railbelt hydro- electric project Chichagof Island Small hydropower project at Tenakee Springs Mahoney Lakes near Ketchikan Southeast hydroelectric project Based on the best information currently available to us, no listed or proposed threatened or endangered species for which the Fish and Wildlife Service (FWS) has responsibility are known to occur in any of the five project locations listed above. You may, therefore, conclude that these projects will have no affect on those species and that preparation of a biological assessment or further consultation with the FWS pursuant to Section 7 of the Endangered Species Act is not required. Protection of threatened or endangered marine mammals is the responsibility of the National Marine Fisheries Service (NMFS). Whereas some of your proposed projects are in or adjacent to marine waters, you may wish to contact NMFS to determine potential effects of the projects on those species. New information indicating the presence of currently listed threatened or endangered species administered by the FWS or the listing of new species which might be affected by the proposed project will require re- initiation of the consultation process. Thank you for your concern for endangered wildlife. As always, personnel of our Endangered Species office are available to. answer your questions. Sistacabe, / ~ b,/77) eeu . Area Director EIS-A-2 APPENDIX EIS-B. CORRESPONDENCE FROM FINAL SCOPING ACTIVITIES (1982) DEPARTMENT OF NATURAL RESOURCES 10-JT1LH 7 OC. STATE OF ALASKA / w+smor som - 619 WAREHOUSE | DR., SUIT ANCHORAGE, ALASKA 99501" " PHONE: 274-4576 : DIVISION OF PARKS — April 27, 1982 File #: 1130-2-1. Harlan E. Moore. . Chief, Engineering Division. Corps of Engineers, Alaska District P.O. Box 7002 Anchorage, AK 99510 Dear Mr. Moore: We have reviewed the "Cultural Resources Assessment for Mahoney Lakes Hydropower Project" (Re: NPAEN-PL-EN) prepared by Julie Steele of your office. In light of Ms. Steele's survey results we concur with the finding of no probable impact to significant cultural. resources by presently proposed construction. However, should cultural resources be located during the course of construction, we request that the project engineer halt al? work which may disturb such, resources and contact our office immediately. As always, thank you for your concern for Alaska's cultural resources. Sincere] Dil) ‘pl ane Historic Preservation Offi Mr. Dave Haas | -2- April 14, 1982 4. The need for this facility in the Ketchikan area shouldbe evaluated. The Swan Lake Hydroelectric Project will soon .be on line and Grace Lake located in the Swan Lake vicinity has been mentioned as a possible hydroelectric power source which may be. ‘constructed after Swan Lake. Do. other alternatives exist?. Thank you for the dior tant to review this proposed project. We look forward to working with the Corps during. completion ‘of this EIS. _ - cc: R. Reed - ADF&G - Juneau H. Moore - COE - Anchorage C. Osborne - USFWS - Ketchikan EIS-B-3 MEMORANDUM _. State of AlasKayi-é" to Dave Haas pare: April 14, 1982 State-Federal Assistance Coordinator in : : Division of Policy Development Fite'no: -AK 820325-02 and Planning . ler Al el Juneau © : "| TELEPHONE NO: © 225-5195 FROM: Don Cornelius : ; SUBJECT: Hahoney Lake Area Habitat Biologist . . : Hydropower Department of Fish and Game : : - . . Feasibility Study Ketchikan ch : ; ale The Department of -Fish.and Game has reviewed information supplied by the U.S. Army Corps-of Engineers regarding Mahoney Lakes Hydropower Feasibi- lity Studies. We have. the’ following comments regarding this proposed project: ee . . 1. The potential effects of this project on red salmon which spawn above lower Mahoney Lake must be investigated. As proposed, the penstock tailrace route would virtually dry up the probable spawn- ing beds of this salmon population by removing water from the stream between Upper and Lower Mahoney. Lakes. 2. Several opportunities for mitigation to protect or enhance fisheries may exist: A. A realignment of the penstock to intersect the lower portion of the channel of the stream between Upper and Lower Mahoney : Lakes may prevent dewatering of this channel. Additional spawning channels could also be created below the tailrace. B. During construction of this project a fish passage structure could be constructed at the Falls between Lower Mahoney Lake and George Inlet. This would facilitate fish movement past this marginally passable obstacle ond potentially improve escapements. C. The potential for fertilizing Mahoney Lake in conjunction with the aforementioned mitigation measures could be evaluated. 3. The proposed facilities should be designed to alleviate problems associated with air entrainment in the penstock which could potenti- ally kill fish with "gas bubble" disease. Project design should include methods to remove gases including nitrogen and oxygen which may Supersaturate the water discharged from the tailrace. EIS-B-2 02-001 A(Rev.10/79) U.S. ENVIRONMENTAL PROTECTION AGENCY 08% - REGION xX aah Ras "es ; 2 % 1200 SIXTH AVENUE j 5 hwy $ SEATTLE, WASHINGTON 98101. g = wwe; NY J 4C -prote fimor, M/S 443 W APR ioe Colonel Lee R. Nunn District Engineer Alaska District, Corps of Engineers P. 0. Box 7002 Anchorage, Alaska .99510 SUBJECT: Mahoney Lakes Hydropower Project, Ketchikan EIS Scoping Suggestions Dear Colonel Nunn: Thank you for inviting the Environmental Protection Agency to participate in the scoping process for the Draft Environmental Impact Statement on the Mahoney Lakes Hydropower Project. One impact to be examined is the project's potential effects on water quality. Parameters of particular concern during project operation include water tempera- ture and dissolved oxygen, nitrogen, suspended sediment, and metal concentra- tions. Existing water quality conditions at all depths of Upper Mahoney Lake should be measured, and the impacts of discharging the-deeper waters of the upper lake into Lower Mahoney Lake should be analyzed. Drawdown of the upper lake and the resulting exposure of unvegetated slopes could affect the upper lake's turbidity and suspended sediment concentrations and should be reflected in the analysis. It may be worthwhile to consider the results of various intake levels on both lakes' water quality. Consideration should also be given to the project's impacts on water quality in the river between the two lakes, highlighting stream temperatures, flows, suspended sediment loads, and the potential for nitrogen supersaturation problems. The evaluations should indicate seasonal impacts, possible miti- gation measures, and whether the operation of the project will cause or contribute to any violations of applicable water quality standards. The water quality impact of construction and maintenance of the access road, transmission line, and penstock and the disposal of tailings from construction of the tunnel should also be discussed. Mitigation measures and alternatives should reflect soil conditions and slopes, and preventive erosion control measures. Attention should also be given to minimizing the water, air, and noise impacts from the construction camp, temporary _generating facility, and obtaining and process construction material such as sand, gravel and rock. EIS-B-4 We appreciate the opportunity.to participate in this scoping process. Dick Thiel, my Environmental Evaluation Branch Chief, may be contacted . for more information. He can ‘be reached at (206) 442- 1728 or (FTS) 399-1728. ‘Gary O'Neal, Director- . Environmental Services. Division Les Sincere] cc: Ron Kreizenbeck, A0O, ‘Juneau EIS-B-5°~ UNITED STATES DEPARTMENT OF AGRICULTURE Tongass’ Wavional Forest Federal Building Ketchikan, Alaska 99901 - . ; 907-225-3101 "3950 - March Nr. Harlan E. Moore —- U. S. Army Engineer District, Alaska ATTN: Chief, Environmental Section P. 0.- Box 7002 Anchorage, Alaska 99510 L . Dear Mr. Moore: Thank you for your March 22 letter concerning the proposed Mahoney Lake hydropower project feasibility study and environmental impact statement. : The Forest Service was a cooperating agency in preparation of the Swan Lake hydropower project and is currently participating in this capacity in preparation of the Black Bear Lake project. This is in line with the Council? on Environmental : Quality Regulations 40 CFR Part 1501.6. To be responsive to these regulations and assure that ‘National Forest Management is appropriately coordinated during the preparation of the environmental statement, I request that the Forest Service be designated as a cooperating agency for the Mahoney Lake hydropower project environmental impact statement. Sincerely, Ee 2222 &. fi feo JAMES A. CALVIN Acting Forest Supervisor 6200-15 (1/69) EIS-B-6 REFERENCES Cunningham, W., and S. Sandford. 1979. Observations of migrating gray _ whales (Eschrichtius robustus) at Cape St. Elias, Alaska- Unpublished manuscript (to be submitted to Fishery’ Bulletin). Jurasz,.C.M., and V.P. Jurasz. 1979. ‘Feeding modes of the humpback whale. Sci. Rep. Whales Res. Inst. 31:69-84 ; EIS-B-9 2 Twice each year virtually the entire eastern. Pacific population of ‘gray whales passes along the outer coast...mostly within-5 km of the beach. The northward migration of animals, by southeast Alaska, without calves takes place from March to early May, with a peak in early April; cows. with calves migrate later. The southward migration takes place during November and December. Gray whales do not feed while migrating along the California coast, but possible surface-feeding behavior has been reported. during spring migration at Cape St. Elias (Cunningham and Stanford 1979). On the summer grounds gray whales feed primarily on benthic gammaridean amphipods. The fin, sei, blue, and sperm whales generally move in and out of the offshore areas seasonally. : The right whale may be resident in the Gulf of Alaska year round and may enter coastal waters frequently. dh The bowhead whale has not been reported.in the Gulf of Alaska. It is our conclusion that the proposed project is not an action that “may affect" endangered or threatened species or their habitat for purposes of regulations implementing Section 7 of the Endangered Species Act of 1973, and thus does not require formal consultation under Section 7. Our agency has not conducted studies on the fish resources inhabiting the Mahoney Lakes system. However, it is our understanding that the upper lakes are barren of fish life. Lower Mahoney Lake and its associated stream system provides habitat for several fish species, i.e., pink ‘salmon, sockeye salmon, chum salmon, coho salmon, steelhead trout, sea-run cutthroat trout and Dolly Varden char. Juvenile sockeye salmon rear in-the lake while juvenile coho salmon, steelhead trout, cutthroat trout; and Dolly Varden char inhabit the lake and stream system. Pink and chum salmon spawn in the stream and their fry migrate, in the spring, to the sea soon after emergence from the stream gravel. Our concern is that construction and operation of a hydropower project on the Mahoney Lake system be compatible with the present fish resources and their habitat requirements. We will offer our comments and recommendations on the proposed project when we review the draft.environmental impact statement. We hope this information will be useful in the planning process. 2 g 7 LES ONT) Robert W. McVey rector, Alaska Region . Sincerely, EIS-B-8 UNITED STATES DEPARTMENT OF COMMERCE Nationa} Oceanic and Atmospheric Administration ‘| National Marine Fisheries Service ' P.O. Box 1668 Juneau, Alaska 99802 March 31, 1982 Colonel Lee R. Nunn District Ergineer Alaska District, Corps of Engineers P.O. Box 7002 : : Anchorage, Alaska 99510 Dear Colonel Nunn: This letter is in response to your Section 7 request for information regarding threatened or endangered species under the National Marine Fisheries Service's . responsibility that may be present in the vicinity of the Mahoney Lake system near Ketchikan, Alaska ; : Endangered Species National Marine Fisheries Service bears responsibility for eight species of endangered whales which occur in Alaskan waters; they are: : Blue - Balaenoptera musculus Sei - Balaenoptera borealis Fin - Balaenoptera physalus Black. Right - Balaena glacial is Bowhead | - - Balaena mysticetus Sperm - Physeter macrocephalus Gray - Eschrichtius robustus Humpback - Megaptera novaeangl jae Humpback whales are probably the only endangered whale that may occur near the project area. About 1,000 humpback whales (of a total world population.of 6,000) inhabit the North Pacific. During the summer feeding season, they range widely from the subarctic boundary (ca. 40° N lat.) north into the Bering Sea. The greatest population densities are reached in certain inshore waters, where the animals appear to be largely resident during the summer and autumn. It is estimated that between 100-260 humpback whales inhabit southeast Alaska. Alaskan humpbacks spend the winter around the Hawaiian Islands and along the west coast of central Mexico. . The main foods of humpback whales in southeastern Alaska are euphausiaceans (Euphausia pacifica), herring (Clupea harengus), and capelin (Mallotus villosus), (Jurasz and Jurasz 1979). Gray whales are endemic to the north Pacific. The eastern Pacific population now numbers about 16,000 animals, whereas the western Pacific population is apparently on the verge of extinction. The eastern population spends the summer in the northern Bering and Chukchi seas, and migrates along the coast to winter grounds on the west coast of Baja California, where the calves are born. : Ss. Setorat ty, United States Department of the Interior FISH AND WILDLIFE SERVICE IN REPLY REFER TO: * 1011 E. TUDOR RD.. . SE ANCHORAGE, ALASKA 99503 (907) 276-3800. 16 MAR 1982 Colonel Lee R. Nunn District Engineer Attention: Mr. William D. Lloyd Alaska District, Corps of Engineers P. O. Box 7002 ‘ Anchorage, Alaska 99510 Re: NPAEN-PL-EN Dear Colonel Nunn: This responds to your March 9, 1982 request for a determination of the presence of proposed or listed threatened or endangered species in the vicinity of a proposed hydropower project at Mahoney Lakes near Ketchikan, Alaska. Based on the best information currently available to us, no such species occur in or near the proposed project area. Hence, a biological assessment is not required. The discovery of threatened or endangered species in the proposed project area or the - designation of new species as threatened or endangered may require a reassessment of this finding. : Thank you for your interest in endangered species. If we can be of further assistance, please contact us. neere}y, 4, L7?. Ob faon— mt Regional Director ce: ES EIS-B-10 fa , a Hee }}) United States Forest Alaska Region P.O. Box 21628 Department of Service Juneau, AK 99802-1628 Agriculture fe Ayrelh beh Reply to: 2770 pate: JUN 08 1993 Ms. Lois D. Cashell ‘Secretary Federal Energy Regulatory Commission 825 North Capitol Street, NE Washington, DC 20426 Dear Ms. Cashell: We have reviewed the March 12 Notice of Application, filed by the City of Saxman, for a preliminary permit for the Upper Mahoney Lake Hydro Power Project No. 11393-000 located northeast of Ketchikan, Alaska. The Federal lands within the project boundary have been selected by Cape Fox Village Corporation, but have not yet been conveyed. Therefore, the lands are still National Forest System lands. rs This proposed project will impact lands and resources within the Tongass National Forest. It is probable that impacts will occur to the following resources: 1. Cultural resources. An inventory will need to be completed before any ground disturbing activities are conducted. There are two reported cultural sites within the project area. 2. Fish habitat. Lower Mahoney Lake provides habitat for resident and anadromous fish. There are reports that sockeye salmon spawn along the shoreline of Lower Mahoney Lake. The impacts of the hydro project on fish populations should be addressed. 3. Scenic values. The project area has high scenic values. The Alpine region is free of human modifications at this time. The proposed dam, penstock, powerhouse, road, and transmission lines will alter the visual integrity of the area. 4. Mountain goats. Fifteen goats were transplanted into the alpine area surrounding Upper Mahoney Lakes in 1991. The direct, indirect, and cumulative effects of the proposed project on the animals needs to be addressed. 5. Birds. As in other projects of this type, the possibility of birds colliding with transmission lines will need to be addressed. Caring for the Land and Serving Peopie FS-6200-28b(3/92) Ms. Lois D. Cashell 6. Access. Road construction to the project across Cape Fox Corporation lands would provide opportunities to access timber on National Forest System lands, and would also provide opportunities for hiking, camping, skiing, and snowmobiling in the alpine area near Ketchikan. The related effects of new roads and changes in access will need to be addressed. It is evident, however, that additional data must be gathered before we can quantify these impacts and their effects upon National Forest Management objectives. Accordingly, the Forest Service “has no objection to the issuance of a preliminary permit subject to the following special condition: Prior to undertaking, any entry or work on National Forest System lands pursuant to a preliminary permit, the Permittee shall prepare and file with the Forest Service a plan of studies to be conducted under the permit; and, the Permittee shall secure a Forest Service special-use authorization and, if appropriate, enter into a Memorandum of Understanding (MOU) with the Forest Service. The Permittee shall file with the Commission, within 90 days of the issuance of this preliminary permit, copies of the special-use permit and, if appropriate, the MOU. The special-use authorization would include Forest Service requirements for fire prevention and control, prevention of damage to Federal property, natural resources, and any requirements for repair or rehabilitation of damage resulting from study activities. The MOU between the Forest Service and the Permittee, if prepared, would document the needs for studies and arrangements for consultation and cooperation not included in the special-use permit. Sincerely, Lidl pee soil Forester ce: Ketchikan WO Lands Mr. Doug Campbell Money LAK Aly 0BS3 00 2-002_ B.10 Chm File March 16, 1994 (See Distribution List) Subject: Mahoney Lake Hydroelectric Project FERC Project No. 11393 Initial Consultation Document (ICD) Dear : The City of Saxman, Alaska, is proposing to construct a small hydroelectric generating plant near Mahoney Lake, about 5 miles northeast of Ketchikan. Title 18 of the Code of Federal Regulations, Section 4.38, requires an Applicant proposing to develop a hydroelectric project to consult with appropriate resource agencies, affected Native American groups, and the public prior to submitting a license application to the Federal Energy Regulatory Commission (FERC). On behalf of the City of Saxman, HDR Engineering, Inc. is hereby initiating the first stage of consultation associated with the above-referenced project. The enclosed consultation document, provides a description of the proposed project configuration, including conceptual design, potential impacts, existing data, and an outline of the studies that are planned. It will be the basis for this first stage of consultation. A joint meeting will be held in Ketchikan within the next 30 to 60 days with the agencies, affected Native American groups, and the general public to further discuss this project and to receive preliminary comments regarding the information contained in the document. We are specifically seeking your input on the adequacy of the existing information for assessing resource values, predicting impacts, and developing mitigation plans. In accordance with FERC regulations, we request that your written comments regarding the proposed studies and study plans that the Applicant expects to perform be submitted within 60 days after the joint meeting. You will receive a letter in the near future confirming the location and date of the meeting as well as an agenda. If you have any questions or need additional copies of the ICD, please contact me or Jack Snyder, the project manager, at (206) 453-1523. We look forward to your participation in this consultation process. Sincerely, HDR ENGINEERING, INC. Mi thal UV Stimde Lag Michael V. Stimac Manager, Licensing & Environmental Services ccs Susan Dickinson, City of Saxman Doug Campbell, Cape Fox Corporation Jack Snyder, HDR Engineering John Braislin, Betts, Patterson, & Mines Don Clarke, Wilkinson, Barker, Knauer & Quinn HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 DISTRIBUTION LIST U.S. Army Corps of Engineers Alaska District Office P.O. Box 898 Anchorage, AK 99506-0898 Ms. Tamra Faris Supervisor-Protected Resources Management Division National Marine Fisheries Service Alaska Region P.O. Box 21668 Juneau, AK 99602-1668 Mr. Nevin Holmbert U.S. Fish & Wildlife Service 3000 Vintage Blvd. Suite 201 Juneau, AK 99801 National Park Service Alaska Region 2825 Gamble Street Anchorage, AK 99503 U.S. Environmental Protection Agency Region X 1200 Sixth Avenue Seattle, WA 98101 U.S. Forest Service Region 10: Alaska Region Box 21628 Juneau, AK 99802-1628 Mr. David Rittenhouse U. S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Gary Laver U.S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Jack Gustafson Alaska Department of Fish and Game Habitat Division 2030 Sealevel Drive, Room 205 Ketchikan, AK 99901 Mr. Frank Rue, Director Alaska Department of Fish and Game Habitat Division P.O. Box 25526 Juneau, AK 99802-5526 Ms. Lorraine Marshall Alaska Office of Management and Budget Division of Governmental Coordination P.O. Box 110030 431 N. Franklin Juneau, AK 99811-0030 Ms. Joan Hughes Alaska Department of Environmental Conservation 410 Willoughby Avenue, Suite 105 Juneau, AK 99801 Mr. Tom Stevenson : Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Ms. Bridget Stearns Ketchikan Public Library 629 Dock St. Ketchikan, AK 99901 The Honorable Alaire Stanton Mayor, City of Ketchikan 334 Front Street Ketchikan, AK 99901 Mr. Jack Pearson City Manager City of Ketchikan 334 Front Street Ketchikan, AK 99901 The Honorable Walter Hickel Governor, State of Alaska P.O. Box 110001 Juneau, AK 99811-0001 Mr. Dick Emerman Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341 Mr. Edgar Blatchford Division of Energy Department of Community and _ Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341 Mr. Riley Snell Alaska Industrial Development Agency 480 W. Tudor Anchorage, AK 99503 Ms. Judith Bittner Alaska Department of Natural Resources State Historic Preservation Office P.O. Box 107001 Anchorage, AK 99510-7001 Mr. John Dunker Alaska Department of Natural Resources/Water 400 Willoughby Avenue Juneau, AK 99801-1796 Department of the Interior Office of Environmental Affairs Anchorage Regional Office 1689 C Street, Room 119 Anchorage, AK 99501-5126 Federal Emergency Management Agency Region 10: Bothell Federal Regional Center 130 228th Street, SW Bothell, WA 98021-9796 Mr. Bill Geary Alaska Department of Natural Resources Parks & Outdoor Recreation 400 Willoughby Avenue Juneau, AK 99801-1796 Mr. Arthur Martin Regional Office Federal Energy Regulatory Commission 1120 SW Fifth Avenue, Suite 1340 Portland, OR 97204 Ms. Lois Cashell Federal Energy Regulatory Commission 825 N. Capitol St. NE Washington, DC 20426 Area Director Bureau of Indian Affairs P.O. Box 3-8000 Juneau, AK 99802 Tongass Conservation Society P.O. Box 3377 Ketchikan, AK 99901 Southeast Alaska Conservation Council 419 Sixth Street, Suite 328 Juneau, AK 99801 Ms. Kate Tessar Alaska Services Group P.O. Box 22754 Juneau, AK 99802 Alaska Environmental Lobby P.O. Box 22151 Juneau, AK 99802 Alaska Public Utilities Commission 1016 W. Sixth Avenue, Suite 400 Anchorage, AK 99501 The Honorable Jim Carlton Mayor, Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Mike Rody Borough Manager Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Gary Munsterman Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Jim Boetberg Ketchikan Gateway Borough 344 Front Street ' Ketchikan, AK 99901 Mr. Steve Segovia Ketchikan District Ranger U.S. Forest Service 3031 Tongass Avenue Ketchikan, AK 99901 Mr. Bob Martin, Director Tlingit-Haida Regional Electrification Authority P.O. Box 210149 Auke Bay, AK 99821 a e : ( WALTER J. HICKEL, GOVERNOR i t ‘ I ‘| 1 i OFFICE OF THE GOVERNOR > 9 9 1004 OFFICE OF MANAGEMENT AND BUDGET DIVISION OF GOVERNMENTAL COORDINATION O sermcemmrnecousores Saar en O recs cneowe ee SOO IRCASTREET.S UN ANCHORAGE, ALASKA 99501-2343 99503-5930 JUNEAU, ALASKA 99811-0300 ; ptapicnecnyitrerareh (907) 561-6134 PH: (907) 465-3562/FAX: (907) 465-3075 PH: (907) 278-8594/FAX: (907) 272-0690 March 23, 1994 Mr Micheal V. Stimac ec: Sryde HDR Engineering, Inc. Foti Suite 1200 Ue 500 108th Avenue, NE Bellevue, WA 98004-5538 Delton : PO ee Dear Mr. Sti "sama File 8.4 SUBJECT: MAHONEY LAKE HYDROELECTRIC PROJECT 01-A35LH FERC Project # 11393 Initial Consultation - STATE ID #AK9403-33JJ The Division of Governmental Coordination received the information that you submitted for the initial consultation review of the Mahoney Lake hydroelectric project. The site for the proposed project is approximately 5 miles northeast of Ketchikan near Mahoney Lake. As the process for obtaining a FERC license requires extensive preapplication assistance, this review is informational in nature. The purpose of this review is for the reviewers to provide you with information about the resource values of the project site, the potential for the project to cause environmental impacts, and to help identify if further studies are necessary. The information provided during this review should assist you in developing the FERC application. A consistency review per the Alaska Coastal Management Program will occur when all permit applications and public notices required for the project are received. When FERC officially accepts the hydroelectric application, a public notice will be issued by that agency. As you know, the second consultation stage and informational review will occur before the State’s consistency review commences. The purpose of the second consultation review will be for reviewers to comment on how their concerns were addressed and to identify permits. The enclosed project information sheet includes a State ID #AK9403-33JJ. Please refer to this number in any future correspondence regarding this review. Appropriate materials have been distributed to participants for their review and comments. Review milestones are also indicated on the enclosed project information sheet. These deadlines were set in accordance with FERC requirements. Packet Distribution List Susan Cantor, EPA, Anchorage Nevin Holmberg, FWS, Juneau Steven Pennoyer, NMFS, Juneau Glen Justis, COE, Anchorage Sincerely ee Christine Valentine Project Review Coordinator March 16, 1994 OFFICE OF Ms. Lorraine Marshall MANAGEMENT & BUDGET Alaska Office of Management and Budget Division of Governmental Coordination MAR 18 1994 P.O. Box 110030 431 N. Franklin GOVERNMENTAL Juneau, AK 99811-0030 COORDINATION Subject: Mahoney Lake Hydroelectric Project FERC Project No. 11393 Initial Consultation Document (ICD) Dear Ms. Marshall: The City of Saxman, Alaska, is proposing to construct a small hydroelectric generating plant near Mahoney Lake, about 5 miles northeast of Ketchikan. Title 18 of the Code of Federal Regulations, Section 4.38, requires an Applicant proposing to develop a hydroelectric project to consult with appropriate resource agencies, affected Native American groups, and the public prior to submitting a license application to the Federal _Energy Regulatory Commission (FERC). On behalf of the City of Saxman, HDR Engineering, Inc. is hereby initiating the first stage of consultation associated with the above-referenced project. The enclosed consultation document, provides a description of the proposed project configuration, including conceptual design, potential impacts, existing data, and an outline of the studies that are planned. It will be the basis for this first stage of consultation. A joint meeting will be held in Ketchikan within the next 30 to 60 days with the agencies, affected Native American groups, and the general public to further discuss this project and to receive preliminary comments regarding the information contained in the document. We are specifically seeking your input on the adequacy of the existing information for assessing resource values, predicting impacts, and developing mitigation plans. In accordance with FERC regulations, we request that your written comments regarding the proposed studies and study plans that the Applicant expects to perform be submitted within 60 days after the joint meeting. You will receive a letter in the near future confirming the location and date of the meeting as well as an agenda. HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 March 16, 1994 Page 2 If you have any questions or need additional copies of the ICD, please contact me or Jack Snyder, the project manager, at (206) 453-1523. We look forward to your participation in this consultation process. Sincerely, HDR ENGINEERING, INC. Mchal Vv Simae Lag Michael V. Stimac Manager, Licensing & Environmental Services ce. Susan Dickinson, City of Saxman Doug Campbell, Cape Fox Corporation Jack Snyder, HDR Engineering John Braislin, Betts, Patterson, & Mines Don Clarke, Wilkinson, Barker, Knauer & Quinn PACKET DISTRIBUTION LIST Joan Hughes, DEC, Juneau Lana Shea, DFG, Juneau Jack Gustafson, DFG, Ketchikan Nate Johnson, DOT/PF, Juneau Elizaveta Shadura, DNR, Juneau John Dunker, DNR/DOW, Juneau Bill Garry, DNR/DPOR, Juneau Judith Bittner, DNR/SHPO, Anchorage Gary Munsterman, Ketchikan Gateway Borough The Honorable Alaire Stanton, Mayor, Ketchikan The Honorable Jim Carlton, Mayor, KGB Susan Dickinson , Cy of Saxman The Initial Consultation Document for the Mahoney Lake Hydroelectric Project was distributed directly to reviewers. If you have not received a copy of the document, you may obtain one from the applicant or DGC. March 31, 1994 (See Attached List) Re: Mahoney Lake Hydroelectric Project FERC Project No. 11393 Joint Agency/Native American/Public Meetings Dear Sir/Madam: This letter is to confirm the joint agency/Native American/public meetings which will be held on Tuesday, April 26, 1994, to discuss development of the Mahoney Lake Hydroelectric Project. The Initial Consultation Document (ICD), which was sent to you via letter dated March 16, 1994, describes the proposed project and studies that are currently planned. At the April 26th meetings, we would like to discuss the proposed project, potential environmental impacts, review the ICD, and discuss the data to be obtained and studies to be conducted as part of the FERC consultation process. As required under 18 CFR 4.38, a public notice will be published regarding the meetings. Day and evening sessions will be conducted. The day session will be held from 10 am to 12 noon in the conference room of the Westmark-Cape Fox Lodge located at 800 Venetia Way in Ketchikan, Alaska. The evening session will be held from 7 p.m. to 9 p.m. at the same location. Attached is the agenda for the meetings. If any agency staff want to visit the site, we will conduct a site visit the afternoon of April 26 or the morning of April 27, weather permitting. Please let us know if you want to attend the site visit. Please call me or Jack Snyder at (206) 453-1523 if you have any questions or comments concerning the Mahoney Lake Hydroelectric Project, the April 26th meetings, or the attached meeting agenda. - We look forward to seeing you at the meetings. Sincerely, HDR ENGINEERING, INC. MM Meme. Michael V. Stimac Manager, Licensing & Environmental Services cc: Susan Dickinson-City of Saxman bec: Debby Howe-HDR Doug Campbell-Cape Fox Corp. Lisa Fortney-HDR John Braislin-Betts, Patterson & Mines Mark Dalton-HDR Don Clarke-Wilkinson, Barker, Knauer & Quinn Neil Macdonald-HDR Jack Snyder-HDR HDR File B.4.1/B.19¢ax.,, John Morsel-NES Chris Campbell-CRS Enclosure HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 NOTE: MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 JOINT AGENCY/NATIVE AMERICAN/PUBLIC MEETINGS APRIL 26, 1994 10:00 a.m. - 12:00 p.m. AND 7:00 p.m. - 9:00 p.m. AGENDA INTRODUCTION LICENSING PROCESS PROJECT DESCRIPTION REVIEW OF STUDY PLANS Water Quality and Quantity Fisheries and Aquatic Resources Wildlife and Botanical Resources Historic and Archaeological Resources Recreational Resources Aesthetic Resources Erosion and Sediment Control Plan COMMENTS AND SUGGESTIONS Both meetings are open to agency personnel and the public. The morning session, however, will be primarily directed toward agency matters and concerns whereas the evening session will be oriented toward the general public. DISTRIBUTION LIST U.S. Army Corps of Engineers Alaska District Office P.O. Box 898 Anchorage, AK 99506-0898 Ms. Tamra Faris Supervisor-Protected Resources Management Division : National Marine Fisheries Service Alaska Region P.O. Box.21668 Juneau, AK 99602-1668 Mr. Nevin Holmbert U.S. Fish & Wildlife Service 3000 Vintage Blvd. Suite 201 Juneau, AK 99801 National Park Service Alaska Region 2825 Gamble Street Anchorage, AK 99503 U.S. Environmental Protection Agency Region X 1200 Sixth Avenue Seattle, WA 98101 U.S. Forest Service Region 10: Alaska Region Box 21628 Juneau, AK 99802-1628 Mr. David Rittenhouse U. S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Gary Laver U.S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Jack Gustafson Alaska Department of Fish and Game Habitat Division 2030 Sealevel Drive, Room 205 Ketchikan, AK 99901 Mr. Frank Rue, Director Alaska Department of Fish and Game Habitat Division P.O. Box 25526 Juneau, AK 99802-5526 Ms. Lorraine Marshall Alaska Office of Management and Budget Division of Governmental Coordination P.O. Box 110030 431 N. Franklin Juneau, AK 99811-0030 Ms. Joan Hughes Alaska Department of Environmental Conservation 410 Willoughby Avenue, Suite 105 Juneau, AK 99801 Mr. Tom Stevenson Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Ms. Bridget Stearns Ketchikan Public Library 629 Dock St. Ketchikan, AK 99901 The Honorable Alaire Stanton Mayor, City of Ketchikan 334 Front Street Ketchikan, AK 99901 Mr. Jack Pearson City Manager City of Ketchikan 334 Front Street Ketchikan, AK 99901 The Honorable Walter Hickel Governor, State of Alaska P.O. Box 110001 Juneau, AK 99811-0001 Mr. Dick Emerman Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341 Mr. Edgar Blatchford Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341. Mr. Riley Snell Alaska Industrial Development Agency 480 W. Tudor Anchorage, AK 99503 Ms. Judith Bittner Alaska Department of Natural Resources State Historic Preservation Office P.O. Box 107001 Anchorage, AK 99510-7001 Mr. John Dunker Alaska Department of Natural Resources/Water 400 Willoughby Avenue Juneau, AK 99801-1796 Department of the Interior Office of Environmental Affairs Anchorage Regional Office 1689 C Street, Room 119 Anchorage, AK 99501-5126 Federal Emergency Management Agency Region 10: Bothell Federal Regional Center 130 228th Street, SW Bothell, WA 98021-9796 Mr. Bill Geary Alaska Department of Natural Resources Parks & Outdoor Recreation 400 Willoughby Avenue Juneau, AK 99801-1796 Mr. Arthur Martin Regional Office Federal Energy Regulatory Commission 1120 SW Fifth Avenue, Suite 1340 Portland, OR 97204 Ms. Lois Cashell Federal Energy Regulatory Commission 825 N. Capitol St. NE Washington, DC 20426 Area Director Bureau of Indian Affairs P.O. Box 3-8000 Juneau, AK 99802 Tongass Conservation Society P.O. Box 3377 Ketchikan, AK 99901 Southeast Alaska Conservation Council 419 Sixth Street, Suite 328 Juneau, AK 99801 Ms. Kate Tessar Alaska Services Group P.O. Box 22754 Juneau, AK 99802 Alaska Environmental Lobby P.O. Box 22151 Juneau, AK 99802 Alaska Public Utilities Commission 1016 W. Sixth Avenue, Suite 400 Anchorage, AK 99501 The Honorable Jim Carlton Mayor, Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Mike Rody Borough Manager Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Gary Munsterman Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Jim Boetberg Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Steve Segovia Ketchikan District Ranger U.S. Forest Service 3031 Tongass Avenue Ketchikan, AK 99901 Mr. Bob Martin, Director Tlingit-Haida Regional Electrification Authority P.O. Box 210149 ‘Auke Bay, AK 99821 $i Ho) for’ ; Fe-64.2 KETCHIKAN PUBLIC UTILITIES alo. 2930 TONGASS AVENUE KETCHIKAN, ALASKA 99901 TELEPHONE 907-225-1000 3; . FAX mae April 1, 1994 Oreseicteg MUNICIPALLY OWNED APR -_ 8 993 ELECTRIC TELEPHONE WATER Mr. Michael V. Stimac Manager, Licensing & Environmental Services HDR Engineering, Inc. Suite 1200 Bellevue, Washington 98004-5538 Dear Mr. Stimac: | have received a copy of the letter and correspondence between you and the Alaska Office of Management and Budget. Please be advised that Ketchikan Public Utilities is the only listed Intervener in the Mahoney Lake FERC filing and as such is entitled to all (i) correspondence regarding this application and all other processes. Your omission of KPU in this correspondence, I’m sure, is simply an oversight and we would appreciate being copied on all further correspondence and on any other past correspondence that you inadvertently may have failed to provide us with a copy. We simply wish to remain fully informed of the project as we will certainly have a vested interest in this project and its effect on the community of Ketchikan. Thank you for your cooperation. Sincerely, KETCHIKAN PUBLIC UTILITIES \ . a WA \\ Ses Thomas W. Stevenson General Manager TWS:nll ce: Mayor Alaire Stanton Mr. Doug Campbell, Cape Fox Corporation Ms. Susan Dickinson, City of Saxman 007-P3.1 WALTER J. HICKEL APR 4 5 joo GOVERNOR P.0.Box 10001 Juneau, Alaske $9811-0001 (807) 465-3500 : Susan Dickirser Savin Pee eee D4 Qn inpotbl -S20 Fx RRP J. Sdn M. Srv, April 8, 1994 D Powe L. For Au, B.4d+4B Io Mon nt a Mr. Michael V. Stimac, Manager of Licensing and Environmental Services HDR Engineering, Inc. Suite 1200 500 108th Avenue NE Bellevue, WA 98004-5538 Dear Mr. Stimac: Governor Hickel is in receipt of your invitation to attend the public meetings on the Mahoney Lake Hydroelectric Project to be held in Ketchikan on April 26, 1994. Although the Governor is unable to participate, I have been advised that a (1) representative from the Department of Community and Regional Affairs will be attending to represent the State of Alaska. Thank you for the invitation, and best wishes for a successful event. Sincerely, Machi, a Kathy Special Assistant for Scheduling cc/enc: Commissioner Edgar Blatchford DEPARTMENT OF NATURAL RESOURCES DIVISION OF PARKS AND OUTDOOR RECREATION Office of History and Archaeology April 13, 1994 File No.: 3130-1R FERC Subject: Project No. 11393, Mahoney Lake Hydro Initial Consultation Document Michael V. Stimac, Manager Licensing & Environmental Services HDR Engineering, Inc. Suite 1200 500 108th Ave., N.E. Bellevue, WA 98004-5538 Dear Mr. Stimac; WALTER J. HICKEL, GOVERNOR 3601 C STREET, Suite 1278 ANCHORAGE, ALASKA 99503 PHONE: (907) 762-2622 MAILING ADDRESS: P.O. Box 107001 ANCHORAGE, ALASKA 99510-7001 ‘ay Clagett (rt Se 14 din Stimlg HOWL APR : 9 1008 Ak ze ‘B.1): mene Thank you for the opportunity to comment on the referenced document. It is our opinion that the study tasks described on pgs. 35-36 will be adequate to identify any significant historic and archaeological resources in the area of potential effect of the project. Please contact Tim Smith at (907) 762-2625 if there are any questions or if we can be of further assistance. Sincerely, Judith E. Bittner State Historic Preservation Officer JEB:tas April 15, 1994 Mr. Thomas W. Stevenson General Manager Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Re: Mahoney Lake Hydroelectric Project FERC No. 11393 Consultation and Correspondence Dear Mr. Stevenson: We are in receipt of your letter of April 1, 1994, regarding KPU’s request for copies of agency correspondence related to the Mahoney Lake Project. We want to assure you that the City of Saxman wishes to keep KPU fully informed of project activities during all phases of the development effort, and it is our policy to provide project information to KPU throughout the licensing process. : To confirm our understanding of FERC’s regulations pertaining to a permittee’s obligations to an intervenor, we contacted Michael Strzelecki, Federal Energy Regulatory Commission (FERC) Project Manager for this project. Mr. Strzelecki confirmed that the intervention process applies to a FERC proceeding, such as the preliminary permit application proceeding. Because the preliminary permit has been issued, the proceeding is now closed and, therefore, there is no further obligation to intervenors by the permittee. As noted in Article 11 of the preliminary permit, however, "the permittee shall, during the term of the permit, consult with the Ketchikan Public Utilities" and as stated earlier, we fully intend to fulfill this requirement. It is our normal procedure to provide parties of record, which includes KPU, with copies of all agency correspondence in the Final Consultation Document and again in the Draft and Final License Applications. This is the procedure we have followed on other projects and intend to use for Mahoney Lake. Thus, KPU will receive copies of all agency correspondence at the specific times noted. Mr. Strzelecki also verified that the permittee is not required to furnish copies of the FERC 6-month progress reports to KPU. However, again in the interest of maintaining good communications, we will mail the progress reports to KPU when they are submitted to the FERC. HDR Engineering, Inc. Suite 1200 : Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 Mr. Thomas W. Stevenson April 15, 1994 Page 2 Thank you for bringing your concerns to our attention. Please do not hesitate to contact us or Michael Strzelecki of FERC (202-219-2827) if you have any questions about this process. Sincerely, HDR ENGINEERING, INC. DM Moklirma Michael V. Stimac Manager, Licensing and Environmental Services cc. Susan Dickinson, City of Saxman Doug Campbell, Cape Fox Corporation Michael Strzelecki, FERC Jack Snyder, HDR Debby Howe, HDR Lisa Fortney, HDR File Mahoney B.4.1 Mv Ea] ¢ OF 2-O0l- 00D \. €.D TI hen b: Notice is hereby given AF AVIT PUBLI that two public meetings | will be held on April 26, | ) 1994, to present xiooee. - tion and receive com- ) ss: ments regarding the devel- ) opment of the Mahoney Lake Hydroelectric Pro- ject, Feder ti ” Comer . . atory ~ Mrnalea m. Bucatte veing Cy Oe anys! (FERC) Project No. 11393. The- pro- ; i i located ap- That she is a representative of the Ketchikan Daily News, a daily i ea be oca ed ; east of Ketchikan, bet- . newspaper published at Ketchikan, in said Borough and State, ween Upper and Lower _ The proposed roject will lication of which the annexed is a printed and consist of a lake tap ap- packers proximately 75 feet below . . r the surface on U; Ma- j true copy, was published in said newspaper at least once a honey Takes Dees F, f fi to cae wats | oy K re rom er one _ au an every _ Aa to Lake tore semi-under. ground powerhouse struc- | successive commencing on the (9° _ h ture. located above Lower | Mahone on oA Pro. os i ect e rated at i day of gL 199_4, and erxiing on the eis (capacity to } supply approximately ! Oto day of Aor) , 199 om 2 3 8,860 homes The pro- | STATE OF ALASKA, Gateway Borough utilize at | / SL ‘oral faces and will not require the constructian ? __Vilimatia Yn Diatiee ite | The meetings will provide ‘ the opportunity\to di Subscribed and sworn to before me this _LS aay of ‘cuss Ee pt ars “pro-{ ject; potential environ- SY mental impacts, and re- , 199. . view data to be obtained | + and studies to be conduct- ! ' ed as part of the FERC. Za consultation “ process. | - Two sessions will be Notary Public for Alaska held. The day session will : be from 10 a.m. to 12 My Commission esones ere OS LIF F Cape Fox Hotel: 800 Ve. ‘ netia Way, Ketchikan, Alaska. The evening ses- sion will from 7 ae to-9 — at the same location. 'urther information may be obtained by contact- ing: Susan Dickenson, City of Saxman, Route 2, Box 1, Ketchikan, AK 99901 or Doug Campbell, aa Fox Corporation, Box 8558, Ketchi-. ae AK 99901, ‘(907)225- : Publish: April 6, 9, 1994, No. 6092 J] NORTHERN ECOLOGICAL ~2) SERVICES ~ 91994 May 4, 1994. Division of Sport Fish Alaska Dept. of Fish and Game P.O. Box 3-2000 Juneau, AK 99802-2000 Attn: Coordinator of Scientific Collecting Permits Dear Sirs: Attached is an application for a scientific collecting permit relating to studies of aquatic habitats in the Mahoney Lake drainage near Ketchikan. The aquatic habitat investigation is part of an overall environmental study program required by Federal Energy Regulatory Commission licensing procedures for the proposed Mahoney Lake Hydroelectric Project. A brief study plan is attached for your information. Northern Ecological Services is a subcontractor to HDR Engineering, Inc. We would appreciate it if you could expedite the permit process so we can have permits in hand by early June. Thank you. ohn W. Morsell Senior Biologist cc. Debby Howe HDR Engineering Inc. 17120 Tideview Drive « Anchorage, Alaska 99516 » (907) 345-4944 “Submit in duplicate to_ Alaska Dept. of Fish and Game, Juneau, Alaska ALASKA DEPARTMENT OF FISH AND GAME APPLICATION for PERMIT to take, possess, hold alive, import into or export from Alaska BIRDS OR THEIR EGGS, MAMMALS (except historically domestic birds, their eggs, and mammals) and FISH AND THEIR EGGS (except goldfish and i tropical fish) FOR SCIENTIFIC OR EDUCATIONAL PURPOSES. I, John Morse) , of (720 (fdwiew De. An . VS name mailing address representing orth i A vites namé&¥ of organization or institution hereby make application for a permit to Z ake specify take, possess, hold alive, export, import, band, etc. \ the following species of fish specify birds, mammals, fish SPECIES NUMBER SPECIES NUMBER erkeye Salmon ( [ayeut Cohn Solan (joa es) zu Dolly Urrdoy Cuttrrent trowe Roinbow trout é Kil | during the period ae ne 6 vo _(ntobae __. Ae ag 9 7. I wish to obtain the above by means wn dh minut day, leaflet, traps, snares, guns, etc Or Ongling from or in the vicinity of ; i \ G & © 11-59 (10/70) TIulat \ hear ketrriknn (over) I wish to delegate authority to conduct activities outlined in this application to NA The purpose of the activities for which a permit is being requested is privide bowen owl lutdrmntion tor pronase Mrbtury Lohse Hy doo ebeatnte \Is t \ final disposition of mammals, birds or their eggs, or fish or their eggs will be the point pt tant I certify that all statements entered on this application are true, that I will abide by all conditions and restrictions of a permit if issued, and promise to submit a report of activities carried out under terms of such permit within 10 days of its expiration date; I further recognize that such permit, if issued, does not authorize collection, possession, or transportation of migratory birds or their nests or eggs except as permitted by, and in conjunction with, a valid permit which may be issued by the Bureau of Sport Fisheries and Wildlife of the U.S. Fish and Wildlife Service. Signature Unless applicant is himself an Owner official of the institution or organization involved, appli- cation must also be signed by such official. Signature of official MAHONEY LAKE HYDROELECTRIC PROJECT FISHERIES AND AQUATIC RESOURCES STUDY PLAN INTRODUCTION A hydroelectric facility is currently proposed for the Mahoney Lakes drainage, near Ketchikan, Alaska. The Federal Energy Regulatory Commission licensing procedures require that an environmental analysis be completed as part of the project development process. Initial plianning and consultation have identified issues relating to fish resources and have resulted in a recommendation that studies of fish resources and fish habitats are needed to provide input to project design and mitigation. FISH POPULATION AND HABITAT UTILIZATION SURVEYS GENERAL METHODOLOGY Because of the varying physical characteristics within the drainage and the variety of fish species utilizing the area, several different techniques will be used to sample and/or observe fish. Techniques may include backpack electroshocker, minnow traps baited with preserved salmon eggs, beach seine, angling, and visual observations (aerial, ground and boat based). The shocker to be employed will be a Smith Root Model 12 with programmable wave form. It is recognized that shocking may be only marginally successful in the low conductivity water of the Mahoney drainage. No shocking will occur in areas where fish of any species are known to be spawning. All fish captured during the study will be identified to species, measured, and returned alive to the place of capture. The study program will emphasize qualitative description of fish presence and habitat usage. However, whenever possible within the context of the overall program, quantitative results will be obtained. For example, if a high density of rearing salmonids is found in a stream reach, it may be possible to estimate number per habitat unit using appropriate capture and population estimation techniques. Visual counts of adult spawners will be carefully conducted to maximize accuracy. UPPER MAHONEY CREEK (FALLS CREEK) Fish abundance and utilization will be surveyed in Upper Mahoney Creek from its mouth upstream to the major waterfall two times per year - June and September. Emphasis @uring early summer investigations will be on a determination of value to rearing juvenile salmonids. The fall surveys will emphasize determination of use by adult salmon spawners. LOWER MAHONEY LAKE The general utilization of fish species in Lower Mahoney Lake will be surveyed in June and September. Emphasis will be on determining the use of the lake for rearing by salmonids including sockeye salmon, Dolly Varden, and cutthroat trout. Use of the lake by _ resident adult Dolly Varden and trout will also be investigated. LOWER MAHONEY CREEK Fish abundance and utilization will be surveyed in Lower Mahoney Creek from its mouth upstream to Lower Mahoney Lake two times per year - June and early September. Emphasis during the June survey will be determination of value to rearing salmonids. Emphasis during the fall survey will be on a determination of value to adult salmon spawners. SOCKEYE SALMON BEACH SPAWNING IN LOWER MAHONEY LAKE The abundance, location, and depth of lake spawning sockeye salmon will be carefully investigated with emphasis on the western end of the lake near the outlet of Upper Mahoney Creek. The timing of the survey(s) will be critical. Observations of Lower Mahoney Creek in early September will provide insight into the movements of adult salmon, and survey timing for detection of lake spawners will be based on the results of these observations as well as input from local observers. It is likely that the peak of spawning will occur in mid to late September. Methods to be utilized will emphasize boat-based visual observations but will also include aerial observations. Since spawning is reported to occur in water as deep as 20 feet, the option of SCUBA diving will also be considered if needed. ANALYSIS OF POTENTIAL IMPACTS TO SOCKEYE SALMON EGG INCUBATION Information obtained from the temperature modelling and analysis study component will be combined with the results of the fish studies to provide an indication of the kinds of effects that the project might have on fish productivity. Emphasis will be on the potential effects of altered temperature regimes on sockeye salmon eggs incubating in lake gravels and on the kinds of mitigation measures that could be employed to alleviate such effects. May 10, 1994 Ms. Lois Cashell, Secretary Federal Energy Regulatory Commission 825 N. Capitol Street, NE Washington, DC 20426 Re: Mahoney Lake Hydroelectric Project FERC Project No. 11393 Audio Tapes of Joint Agency/Native American/Public Meetings Dear Ms. Cashell: Enclosed are two cassette tapes which are the audio recordings of the Stage I Consultation joint agency/Native American/public meetings that were held on April 26, 1994, for the above- referenced project. They are being submitted in accordance with 18 CFR 4.38(b)(3). Both morning and evening sessions are included. Additional copies of these recordings are available in our office, upon request, to any resource agency or Indian tribe. Sincerely, HDR ENGINEERING, INC. Michael V. Stimac Manager, Licensing & Environmental Services MVS/laf cc: Veronica Slajer, City of Saxman Doug Campbell, Cape Fox Corporation Emesta Ballard, Cape Fox Corporation John Braislin, Betts, Patterson & Mines Don Clarke, Wilkinson, Barker, Knauer, & Quinn HDR File, B.4.1 /B. Ip— HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 May 13, 1994 (See Attached List) Re: Mahoney Lake Hydroelectric Project FERC No. 11393 Dear : Enclosed are the minutes from the April 26, 1994, initial consultation meetings for the above-referenced project. As a reminder, resource agencies are requested to submit their written comments regarding the Initial Consultation Document to HDR as soon as possible but no later than June 25, 1994. We look forward to your continued participation in this project. Sincerely, HDR ENGINEERING, INC. Michael V. Stimac Manager, Licensing & Environmental Services Enclosure ce: Veronica Slajer, City of Saxman Doug Campbell, Cape Fox Corporation Emesta Ballard, Cape Fox Corporation Don Clarke, Wilkinson, Barker, Knauer, & Quinn HDR File, B.4.1 HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 DISTRIBUTION LIST U.S. Army Corps of Engineers Alaska District Office P.O. Box 898 Anchorage, AK 99506-0898 Ms. Tamra Faris Supervisor-Protected Resources Management Division National Marine Fisheries Service Alaska Region P.O. Box 21668 Juneau, AK 99§02-1668 Mr. Nevin Holmbert U.S. Fish & Wildlife Service 3000 Vintage Blvd. Suite 201 Juneau, AK 99801 National Park Service Alaska Region 2825 Gamble Street Anchorage, AK 99503 U.S. Environmental Protection Agency Region X 1200 Sixth Avenue Seattle, WA 98101 U.S. Forest Service Region 10: Alaska Region Box 21628 Juneau, AK 99802-1628 Mr. David Rittenhouse U. S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Gary Laver U.S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Jack Gustafson Alaska Department of Fish and Game Habitat Division 2030 Sealevel Drive, Room 205 Ketchikan, AK 99901 Mr. Frank Rue, Director Alaska Department of Fish and Game Habitat Division P.O. Box 25526 Juneau, AK 99802-5526 Ms. Lorraine Marshall Alaska Office of Management and Budget Division of Governmental Coordination P.O. Box 110030 431 N. Franklin Juneau, AK 99811-0030 Ms. Joan Hughes Alaska Department of Environmental Conservation 410 Willoughby Avenue, Suite 105 Juneau, AK 99801 Mr. Tom Stevenson Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Ms. Bridget Stearns Ketchikan Public Library 629 Dock St. Ketchikan, AK 99901 The Honorable Alaire Stanton Mayor, City of Ketchikan 334 Front Street Ketchikan, AK 99901 Mr. Jack Pearson City Manager City of Ketchikan 334 Front Street Ketchikan, AK 99901 The Honorable Walter Hickel Governor, State of Alaska P.O. Box 110001 Juneau, AK 99811-0001 Mr. Dick Emerman Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341 Mr. Edgar Blatchford Division of Energy Department of Community and Regional Affairs 333 W. Fourth Avenue, Suite 220 Anchorage, AK 99501-2341 Mr. Riley Snell Alaska Industrial Development Agency 480 W. Tudor Anchorage, AK 99503 Ms. Judith Bitter Alaska Department of Natural Resources State Historic Preservation Office P.O. Box 107001 Anchorage, AK 99510-7001 Mr. John Dunker Alaska Department of Natural Resources/Water 400 Willoughby Avenue Juneau, AK 99801-1796 Department of the Interior Office of Environmental Affairs Anchorage Regional Office 1689 C Street, Room 119 Anchorage, AK 99501-5126 Federal Emergency Management Agency Region 10: Bothell Federal Regional Center 130 228th Street, SW Bothell, WA 98021-9796 Mr. Bill Geary Alaska Department of Natural Resources Parks & Outdoor Recreation 400 Willoughby Avenue Juneau, AK 99801-1796 Mr. Arthur Martin Regional Office Federal Energy Regulatory Commission 1120 SW Fifth Avenue, Suite 1340 Portland, OR 97204 Ms. Lois Cashell Federal Energy Regulatory Commission 825 N. Capitol St. NE Washington, DC 20426 Area Director Bureau of Indian Affairs P.O. Box 3-8000 Juneau, AK 99802 Tongass Conservation Society P.O. Box 3377 Ketchikan, AK 99901 Southeast Alaska Conservation Council 419 Sixth Street, Suite 328 Juneau, AK 99801 Ms. Kate Tessar Alaska Services Group P.O. Box 22754 Juneau, AK 99802 Alaska Environmental Lobby P.O. Box 22151 Juneau, AK 99802 Alaska Public Utilities Commission 1016 W. Sixth Avenue, Suite 400 Anchorage, AK 99501 The Honorable Jim Carlton Mayor, Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Mike Rody Borough Manager Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Gary Munsterman Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Jim Boetberg Ketchikan Gateway Borough 344 Front Street Ketchikan, AK 99901 Mr. Steve Segovia Ketchikan District Ranger U.S. Forest Service 3031 Tongass Avenue Ketchikan, AK 99901 Mr. Bob Martin, Director Tlingit-Haida Regional Electrification Authority P.O. Box 210149 Auke Bay, AK 99821 Ms. Marlene Finley Ketchikan Ranger District U. S. Forest Service 3031 Tongass Ave. Ketchikan, AK 99901 Mr. Don Ranne Ketchikan Ranger District U.S. Forest Service Federal Building Ketchikan, AK 99901 Mr. Steve Hoffman Alaska Department of Fish and Game Habitat Division 2030 Sea Level Drive, Room 205 Ketchikan, AK 99901 Mr. Rich Trimble Ketchikan Public Utilities 2930 Tongass Avenue Ketchikan, AK 99901 Ms. Mary Klugherz McDowell Group 320 Dock St., #201 Ketchikan, AK 99901 Ms. Phyllis Yelte Assembly Member Ketchikan Gateway Borough Box 958 Ward Cove, AK 99901 Ms. Barnes Alaska Forest Association 111 Stedman, Suite 200 Ketchikan, AK 99901 Ms. Christine Valentine Alaska Office of Management and Budget Division of Governmental Coordination P.O. Box 110030 431 N. Franklin Juneau, AK 99811-0030 MEETING MINUTES h:\hyd\mahoney\stage1\0426mtg min PROJECT: Mahoney Lake Hydroelectric Project, FERC No. 11393 SUBJECT: Joint Agency/Native American/Public Meetings, Moming Session DATE: April 26, 1994 PLACE: Ketchikan, Alaska ATTENDEES: Susan Dickinson, Veronica Slajer-City of Saxman; Jim Carlton-Ketchikan Gateway Borough; Rich Trimble-Ketchikan Public Utilities; Steve Hoffman, Jack Gustafson-ADF&G; Don Ranne, Marlene Finley-USFS; Mary Klugherz-McDowell Group; Don Clarke-Wilkenson, Knauer, Barker & Quinn; Doug Campbell, Emesta Ballard-Cape Fox Corporation; John Morsell-Northern Ecological Services; Debby Howe, Mark Dalton, Vickie Bakker, Mike Stimac, Jack Snyder, Lisa Fortney-HDR Engineering. The meeting began at 10:10 am. A handout package (copy attached) and the Initial Consultation Document (ICD) were available for attendees. Doug Campbell welcomed everyone and introduced Jack Snyder, the project manager for the Mahoney Lake Project from HDR Engineering. Jack Snyder explained the protocol for the meeting to comply with FERC regulations (€.g., audio recording, identifying yourself before speaking, etc.) Jack Snyder summarized how the proposed project would operate. He described the project design and its location between Upper and Lower Mahoney Lakes. He explained that the natural topography of the land drops 1,800 ft. in less than a mile, making it an ideal place for a hydroelectric site. He presented a topographic map of the area and pointed out where the existing logging road is and how it will be extended south around the lower lake. The transmission line will be buried from the powerhouse to the existing logging road and then continue as an overhead line to the Swan Lake Intertie. Jack Snyder explained that most of the project would be underground. An upper tunnel would be located about 80 ft. below the lake surface (lake tap) and would convey water to a vertical shaft. This would drop 1,200 ft. and continue to a lower tunnel which would run to the powerhouse. A small house will be situated at the top of the vertical shaft. The only other visible features of the project would be the powerhouse, access road, and overhead portion of the transmission line. The powerhouse location was chosen because of the impassable barrier to upstream migration of fish. Jack explained the operation of the impulse turbines, that they are not submerged but rotate in the air. Jack Snyder discussed the hydrology of the project area and stated that 12 years of actual recorded data was obtained for Mahoney Creek. Two gages were located near the project; one near the upper creek and one on the lower creek. They were used to simulate a long-term flow record. Fifteen percent of the time the flow is greater than 85 cfs. Jack explained how the upper lake can be raised and lowered to meet power demands. He discussed Ketchikan’s energy requirements and savings in diesel fuel if the Mahoney Lake Project is developed. He discussed the anticipated project schedule. A videotape of aerial footage for the project area was shown. A question was asked regarding ice on the upper lake. Jack Snyder responded that it was about 2 to 3 feet thick and that ice formation will be verified when the studies are conducted. Mike Stimac described the FERC Licensing process. He stated that the preliminary permit was received in June 1993 and expires in May 31, 1996. A license application must be submitted to the FERC by May 31, 1996. He also talked about the three-stage consultation requirements. From the date of this meeting, the agencies have 60 days to respond with their comments and concems on the project and the proposed studies discussed in the ICD. HDR should receive written agency comments by June 25, 1994. Mike described the required exhibits in a license application. Veronica Slajer (City of Saxman) asked when the 60-day clock begins. Mike Stimac replied that it started today and would end on June 25th. Vickie Bakker discussed the proposed water quality studies. She explained she would like to Teceive agency input on the proposed studies. The water quality studies would include continuous temperature monitoring and monthly water quality sampling. Data analysis would be conducted to relate temperatures at the intake and tailrace to predict temperatures in spawning gravels in the lower lake downstream of the project area. Questions: None. John Morsell discussed the proposed fishery studies. He stated that he had older information pertaining to the fisheries of Mahoney Lake and that if anyone knew of any recent studies, the newer information would be appreciated. He explained which fish species inhabit the lake and creek and that sockeye salmon spawn along the western shore of Lower Mahoney Lake. The proposed studies would update and expand on the existing data. Two field visits are anticipated in June and in September to coincide with sockeye spawning. Impacts to these spawning gravels will be determined and suitable mitigation measures developed. Jack Snyder asked John to discuss Upper Mahoney Lake. John explained that previous documentation showed that no fish exist in Upper Mahoney Lake and that fish cannot migrate to the upper lake from the lower lake because of the waterfalls. Questions: None. Mark Dalton discussed the proposed wildlife and botanical studies. Mark stated that he is looking to the agencies to help update existing data. Aerial photos will be reviewed and 2 preliminary office-based wetland mapping will be conducted. A field survey will be conducted in mid-June and will include ground truthing, habitat mapping, and wetland mapping. If necessary, bald eagle nesting survey and other bird surveys will be conducted. In regard to permitting, a stream crossing Title 16 permit and Corps of Engineers permit are anticipated. Questions: None. Lisa Fortney discussed the proposed archaeological and historical studies. She stated that a cultural study of the Mahoney Lake area was conducted in 1981 by the Army Corps of Engineers and conclusions from that study indicated that there would be no impacts to cultural tresources from the project as it was proposed at that time. Correspondence from the Alaska State Historic Preservation Office (SHPO) also indicated concurrence with this finding. There were no known sites eligible for status on the National Register of Historic Places. Two cultural sites are located near the project—one is a petroglyph located in a cove east of the lower lake and the other is an abandoned mine located near the mouth of Mahoney Creek. Cultural Resources Consulting will conduct a new cultural study to update and verify the findings of the previous report. This will entail performing a literature search of the previous use of lands around the project area. The SHPO will be contacted for any additional information of known cultural sites within the area as well as the Cape Fox Corporation. The National Park Service and the U.S. Forest Service will also be consulted for any concerns they may have in relation to cultural properties and to ensure compliance with Section 106 of the National Historic Preservation Act. An archaeological field survey will be conducted to identify any evidence of historical or archaeological significance. A Draft Cultural Assessment Report will be developed from the results of the cultural survey. Questions: None. Debby Howe discussed the proposed recreation studies. She stated that existing recreation Tesources would be evaluated, agencies would be consulted and data collected. The USFS Plan, USFS ROS, and recreation inventories would be reviewed. The project is not located within any National Wild and Scenic River Systems, National Trails Systems or any wilderness areas designated under the Wilderness Act. Any proposed recreation plans or future policies for the area will be reviewed to evaluate future recreation potential. Recreation demand will be estimated based on past trends, population and demographic forecasts. Recreation opportunities will be evaluated to see if the demand can be met. The project impacts will be assessed. Debby stated that there are no recreation facilities at the project site. A recreation mitigation plan will be developed if it is determined that the project would impact potential recreation opportunities and that there is a demand for recreation in the project area. Questions: None at this time. (Some recreation-related questions were asked later.) Debby Howe discussed the proposed aesthetic studies. She explained how the existing visual conditions will be evaluated by using the USFS Visual Management System to describe the natural visual character of the project area. Impacts from construction activities and project features will be determined and assessed. Most of the project is underground and the most visible features would be the access road and the transmission line. Impacts from reducing the 3 flows over the waterfall between Upper and Lower Mahoney Lakes will be assessed. Mitigation measures to reduce impacts to aesthetic resources will be developed and could include architectural designs and landscaping. Veronica Slajer (City of Saxman) asked if there would any sounds from the powerhouse. Debby teplied that there would not be any noticeable noise and that noise studies are not proposed. Mary Klugherz (McDowell Group) asked if recreation as it relates to tourism would be reviewed. Debby replied that yes, tourism would be considered during the recreation studies. Marlene Finley (USFS) stated that there is some existing recreation use in the project area. Debby Howe agreed that there is some passive recreation usage in the area, but no developed Lisa Fortney discussed the proposed land use studies. She stated that the two land owners are the USFS and the Cape Fox Corporation. The upper portion of the project would be located on USFS land and that portion includes the lake tap, the vertical shaft, and most of the tunnels. Cape Fox owns the area around the powerhouse, access road, and the transmission line route. The project would be reviewed for consistency with the Tongass National Forest Plan, the Alaska Coastal Zone Management Plan, the Ketchikan Gateway Borough Coastal Zone Management Program, and any other plans. A Special Use Permit Application will be submitted to the USFS concurrent with the Final License Application to the FERC for use of federal lands for power generation. Jack Snyder discussed the proposed erosion and sediment control studies. He reiterated that most of the project will be buried and that erosion and sediment control measures will include spoils from tunnel excavation and that spoils areas will be designated. Jack asked if there were any other questions. There were none. Jack explained that the results of these studies will make up the Exhibit E of the license application. The agency comment period ends on June 25th and HDR would appreciate receiving a comment letter from all of the agencies. Even if the agency has no concerns at this time, a letter stating "No comment" would be appreciated. The study plans will be finalized by incorporating any agency comments and distributed again after June 25. Jack stated that a site visit was required by the FERC regulations. Representatives from Alaska Fish & Game had already indicated they would attend and if anyone else was interested in attending to please see him after the meeting. Rich Trimble from KPU stated for the record that KPU has grave concerns about the Mahoney Lake Project and the timing of it all because it competes with the Swan-Tyee Intertie Project that KPU is pursuing. KPU is on the eve of receiving state funding for this project. At this point, KPU does not support the Mahoney Lake Project. Jack Snyder responded that FERC regulations require the City of Saxman and the Cape Fox Corporation to proceed with consultation and project studies under the terms of the preliminary 4 permit. Jack explained how both the intertie project and the Mahoney Lake Project could meet the power needs of Ketchikan. Mary Klugherz (McDowell Group) asked about the cost and financing for the project. Jack replied that costs would be around $30 million. The results of the studies could impact final design and these costs will be refined during development of the license application. Financing for the project can be handled in a number of ways--being a municipality, the City of Saxman is allowed to sell bonds; the U.S. Department of Interior has a grant program that it administers through the Bureau of Indian Affairs; or a Farmers Home Administration loan is another option. Rich Trimble said that KPU was trying to get state financing for the Swan-Tyee Intertie Project and the Mahoney Lake Project puts doubts in the legislators minds about the need for the intertie project. Jack Snyder explained how the two projects compare to each other. This project hasn’t been compared to the intertie on a head to head basis yet. We would like to have the opportunity to have Mahoney Lake be compared to the intertie to find out which project is most beneficial for the public. Mary Klugherz (McDowell Group) asked how the Mahoney Lake Project would work with KPU and power supply. Jack Snyder replied that it could be operated in several different ways. Base load could be generated to feed into the Swan Lake Intertie. It could be used during a power outage for up to 10 MW if power is needed. The project provides flexibility and could be operated in conjunction with other KPU projects. The Mahoney Lake Project will not provide for all the energy needs of Ketchikan but will provide an additional long term source of energy to the area. The meeting adjourned about 11:45 am. Although they had originally planned to go on the site visit, Jack Gustafson and Steve Hoffman with Alaska Department of Fish and Game decided not to attend at this time and stated they would go out to the site with John Morsell (Northern Ecological Services) when he starts his fishery studies. Mr. Gustafson recommended that the site visit planned for September (to coincide with sockeye spawning) be carefully planned so as to not miss the spawning season in case it actually occurs sooner. MEETING MINUTES PROJECT: Mahoney Lake Hydroelectric Project, FERC No. 11393 SUBJECT: Joint Agency/Native American/Public Meetings, Evening Session DATE: April 26, 1994 PLACE: Ketchikan, Alaska ATTENDEES: Phyllis Yelte, Ketchikan Gateway Borough; Ms. Barnes-Alaska Forest Association; D. Campbell-Cape Fox Corporation; V. Slajer, S. Dickinson- City of Saxman; J. Snyder, M. Stimac, D. Howe, M. Dalton, V. Bakker, L. Fortney-HDR Engineering; J. Morsell-Northern Ecological Services The evening session was scheduled to begin at 7:00 pm. Two people registered for this session. Jack Snyder reviewed the Initial Consultation Document and explained the Mahoney Lake Project. The meeting adjourned at 9:00 pm. MAHONEY LAKE HYDROELECTRIC PROJECT FERC PROJECT NO. 11393 JOINT AGENCY/NATIVE AMERICAN/PUBLIC MEETINGS APRIL 26, 1994 ° 10:00 a.m. - 12:00 p.m. and 7:00 p.m. - 9:00 p.m. AGENDA I. INTRODUCTION ere cpeteiereieletielial sie) ciaieiclelisicisietelenelelenels Doug Campbell Cape Fox Corporation I. PROJECT DESGRIPTION “530 oc cis si ae eles cre ce) ee) se Jack Snyder HDR Engineering, Inc. I. FERC LICENSING PROCESS) ooo oc fone o) 01) 0 oo eclieyel eral a Mike Stimac HDR Engineering, Inc. IV. REVIEW OF STUDY PLANS Water Quality and Quantity .................. Vicki Bakker HDR Engineering, Inc. Fisheries and Aquatic Resources ............... John Morsel Northern Ecological Services Wildlife and Botanical Resources ..............- Mark Dalton HDR Engineering, Inc. Historic and Archaeological Resources ......... Chris Campbell Cultural Resources Consulting Recreational Resources .............0eeeeeee Debby Howe HDR Engineering, Inc. Aesthetic Resources .... 0. ccccccccccsscsecs Debby Howe : HDR Engineering, Inc. Bard) Use irereyer-) aie olelereiclel tener cheloicleacierelencrororenciene Lisa Fortney HDR Engineering, Inc. Erosion and Sediment Control Plan ............. Jack Snyder HDR Engineering, Inc. V. COMMENTS AND SUGGESTIONS ARCTIC. OCEAN paciric Ocean LOCATION MAP VICINITY MAP QTY OF SAXWAN, ALASKA PROJECT LOCATION MAPS FIGURE 1-1 HOR Engineer! Inc. a me mm. Ase2_| aa PPR MACON Lae MORN, EOL 18580 UPPER wart sueract GL 1990 _ MAHONEY arenomuart A ete Veen ro LAKE ” -“ wotrwartE contoun . - - SeSTAC A MLOW MELASE PPE (ROUTE 10 Stacaus # MCOURCO) es + ene on eur \ \ \\ y V\I// N \/7~SWITCHYARD *. LI MAN'S i avs ay oe i é , a 8 wW > ih a 2 oF Three-Stage FERC Hydroelectric Licensing, HR Relicensing, and Amendment Process Dn. RELICENSE Notice of intent to Acceptance of File for New License i i LICENSE z i z Initial Consultation, Documents DA jes and the Public AMENDMENT Joint Agency & Public Meeting(s), Cor Cali(s,) Site Visit FIRST STAGE CONSULTATION Written Responses "Final Determnaton® Draft Licensit Agency AMENDMENT PLAN Pasiiemee tama Plan Submit Request for Dispute Resolution to FERC for Unreasonable Agency Study Requirements SECOND STAGE CONSULTATION Submit Final Application to FERC & Necessary Studies Prepare Report on Additional Studies Letter from FERC: Acceptance/Deficiencies/ Request for Additional information THIRD STAGE LICENSING STUDY PLANS WATER QUALITY AND QUANTITY Purpose The purpose of these studies is to determine water quality in both Upper and Lower Mahoney Lakes and to establish baseline information. Data results of consultations with appropriate agencies and other interested parties will be presented in a Water Use and Quality Report for inclusion in the Exhibit E, Environmental Report, of the Project’s License Application. Methods Agencies will be consulted and existing information collected. Additional study tasks will be conducted including literature review, and water quality and quantity measurements. Agencies to Be Consulted a USFWS ® COE a Alaska Department of Natural Resources (ADNR) Existing Information Water Quality Existing temperature data will be updated (See Appendix D). Sources of existing information may include USFWS, COE, and ADNR. Water Quantity Sources of existing stream flow information are described in Section 5.0 of this document. Study Tasks Literature Review The Applicant will investigate the following sources of information: a USFS a United States Geological Survey a USFWS a COE a ADNR a ADFG Water Quality Water quality at the base of the waterfalls (powerhouse site) and at Lower Mahoney Lake will be measured monthly for one year. Measurements included will be temperature, pH, turbidity, dissolved oxygen, and total suspended solids. Temperature Model Analysis Temperature will be continuously monitored in Upper Mahoney Lake near the proposed intake location with emphasis on placing one temperature probe at the same depth as the proposed intake and one at the lake surface. Such monitoring will be initiated in the summer of 1994 and temperature readings will be logged at two-hour intervals. In addition, temperature profile according to depth from surface to bottom will be measured within deeper portions of Upper Mahoney Lake four times per year (late summer, fall, late winter, late spring) to determine stratification patterns. Stream water temperature will be continuously monitored (two-hour intervals) in Lower Mahoney Creek near the proposed tailrace discharge location. Air temperature will also be measured at this same location and at the same intervals as stream temperature. Temperature within the lake bottom substrate and just above the lake bottom in Lower Mahoney Lake will be continuously monitored at two locations at the west end of the lake at known sockeye salmon spawning areas (probable upwelling areas). The intragravel probes will be buried about 25 cm below the lake bottom and the lake water probes will be placed about 10 cm above the bottom at the same location as the buried probes. One dual-channel data logging device will be placed onshore and used to record data at each upwelling monitoring site. Temperatures will be logged at two-hour intervals. In addition, temperature profiles according to depth from surface to bottom will be measured within deeper portions of Lower Mahoney Lake four times per year to determine stratification patterns. Water Quantity Stream flow will be measured near the Project using a Stevens Type AA or Unidata digital continuous stream gage recorder. On Mahoney Creek, one unit will be installed near the proposed powerhouse location. The exact location of the gage will depend on stream character, terrain, and access. The stream gage will be installed during spring/summer of 1994 and will continue operating for the life of the Project. Results The relationship between Upper Mahoney Lake and creek water temperatures, air temperatures, and Lower Mahoney Lake upwelling water temperatures will be analyzed. This information will be used to help predict post-Project water temperatures within the upwelling areas used by salmon as spawning grounds. The information may also be used to develop mitigation measures to reduce the impacts of water temperature on salmon egg incubation. Information collected will be presented in a draft report and provided to the agencies of record for their comments. After review, any appropriate adjustments to the draft will be incorporated 2 into the final report. The format for the report will be in conformance with the requirements for the FERC License Application, Exhibit E (18 CFR 4.41). FISHERIES AND AQUATIC RESOURCES Purpose Objectives of the fisheries and aquatic studies are to: a) determine existing fisheries resources above, within, and below the diversion reach; b) determine the potential Project impact on fisheries resources; and, c) develop measures to avoid, minimize, and mitigate impacts on fisheries resources. Methods Agencies will be consulted and existing information collected. Additional studies to be conducted include: a Fish population surveys Agencies to be Consulted USFWS NMFS USFS COE ADFG Existing Informati Information for the Mahoney Lake drainage may be available from the USFWS, NMFS, COE, USFS, and the ADFG from previous studies. Some of the existing information is included in Appendix B. Tasks Fish Population Surveys Fish abundance and utilization will be surveyed in Mahoney Creek from its mouth in Lower Mahoney Lake upstream to the major waterfall two times per year - June and early September in 1994. Visual observations as well as electroshocking and minnow trapping will be used to determine the presence, abundance, and habitat utilization of major fish species. Emphasis will be on a determination of value to rearing juvenile salmonids as well as value to spawning adults. Confirmation of reports that the streambed is sometimes dry will be made. The abundance and location of lake spawning sockeye salmon will be carefully investigated with emphasis on the western end of Lower Mahoney Lake near the outlet of Upper Mahoney Creek. Surveys will be conducted in early to mid-September of 1994 to coincide with the peak of spawning activity. Methods to be utilized will be determined after further review of existing fish 3 study information and observation of the lake physical characteristics. Methods may include aerial visual surveys, boat-based visual surveys, SCUBA diving, and/or snorkeling. In addition, a minnow trap survey will be conducted in June and September to gain insight into the general use of the lake by rearing fish. Fish abundance and utilization will be surveyed in Lower Mahoney Creek from its mouth upstream to Lower Mahoney Lake two times in 1994, June and early September. Visual observations and minnow trapping will be used to determine the presence, abundance, and habitat utilization of major fish species. Emphasis will be on a determination of value to adult salmon spawners. Results Information obtained from the temperature modelling and analysis study component will be combined with the results of the fish studies to provide an indication of the kinds of effects that the Project might have on fish productivity. Emphasis will be on the potential effects of any altered temperature regimes on sockeye salmon eggs incubating in lake gravels and on the kinds of mitigation measures that could be employed to alleviate such effects. Information collected will be presented in draft reports and provided to the agencies of record for their comments. After review, any appropriate adjustments to the drafts will be incorporated into final reports to be included in the appendix of the FERC License Application. The Fisheries Resource section of the FERC License Application will be prepared incorporating the study results and in accordance with the FERC regulations (18 CFR 4.41). WILDLIFE AND BOTANICAL RESOURCES Purpose The purpose of the wildlife and botanical studies is to describe, map, and quantify the habitats or cover types in the Project area. The potential impact of the Project on these resources will be evaluated and measures to avoid, minimize, or mitigate impacts will be developed. Methods Because many aspects of botanical resources and wildlife habitat are closely related, for the most part, both resources will be studied simultaneously. The studies will include agency consultations, literature reviews, field studies, interpretation of field data, analysis of aerial photographs, and documentation. Agencies to be Consulted: 2 USFWS 2 USFS 2 ADNR 2 ADFG Tasks Preliminary Review In this phase, all existing data on plant and animal species and wildlife habitats in or near the Project area will be reviewed (Appendix B). For the Mahoney Lake Hydroelectric Project this will include lists, survey data, and reports from the ADNR and USFS. Under Section 7 of the Endangered Species Act, a species list request will be submitted to the USFWS. Habitat and cover types maps will be updated using the most current set of aerial photographs and field verified through random sampling and consultation. Field Surveys ‘Two field visits will be conducted 10 confirm existing Project data. Areas to be surveyed will include the upper lake tap tunnel entrance area, powerhouse site, and the access road/transmission line route. Field studies will confirm presence/absence of common plants and animals, as well as species of concern (i.e., threatened and endangered species). The field survey will consist of: a) qualitative surveys of wildlife habitats and plant communities; b) a general inventory of individual plant and animal species; and c) obtaining general information on topography and historical land use. Special habitats (e.g., wetlands, cliffs, old growth forests, etc.) will be located and examined in a broader area. General wildlife surveys will be conducted for mammals and birds. Ancillary observations will include identification of calls, tracks, scat, and raptor pellet analysis. The Project team will survey the Project area while walking to and from fixed points. Threatened and endangered species which may require additional habitat evaluation could include the bald eagle and marbled murrelet. The appropriate extent of the analysis area for other _ potential animal species will be determined in consultation with the agencies. If individuals of an animal or plant species of concern are located, the pertinent officials will be informed. Results Results of preliminary review and field surveys will be used to assess the potential effects of the Project on botanical and wildlife resources. Mitigation measures will be developed for species of concern in consultation with appropriate agencies. Information collected will be presented in a draft report and provided to the agencies of record for their comments. After review, any appropriate adjustments to the draft will be incorporated into the final report. The format for the report will be in conformance with the requirements for FERC License Applications, Exhibit E (18 CFR 4.41). HISTORIC AND ARCHAEOLOGICAL RESOURCES Purpose The purpose of these studies is to develop information on the nature and distribution of cultural Tesources within the Project area that have not been previously surveyed (a portion of the access toad). This information, together with professional opinions and consultations with affected Native American groups and agencies, will be presented in a written cultural resources report for inclusion in the Exhibit E, Environmental Report, of the Project’s License Application. Methods Agencies and Native American groups will be consulted and background research will be conducted. An archaeological/cultural resources field survey will also be performed. Study Tasks Background Research Background research will be conducted on the prehistoric, ethnohistoric, and historic use of lands within and around the Project area. Survey records and cultural resource inventories and registers maintained by the Alaska State Historic Preservation Office (SHPO) will be reviewed. Native American and Agency Consultation The Cape Fox Corporation and other interested Native American groups will be consulted to identify potential cultural heritage or traditional religious resources or concerns in the Project area. If the archeological field survey locates prehistoric and/or ethnohistoric cultural resources, these grouped will be provided information on the resources, which will remain confidential. " ‘The SHPO, the National Park Service (NPS), and the USFS will also be consulted during each phase of the cultural resources assessment to ensure compliance with FERC regulations and the requirements of Section 106 of the National Historic Preservation Act, as amended. Archeological Field Survey An archeological field survey of the areas to be disturbed by the proposed site development will be conducted. Maps and aerial photographs will be used in conjunction with information on past land use and previously recorded cultural resources to identify geomorphic features within the Project area. Environmental and geomorphic information will be recorded for areas surveyed. The location, condition, and potential significance of cultural resources identified during the field survey will be recorded on site forms acceptable to the SHPO and the NPS. Field work will be documented with notes, drawings, and photographs as needed to record field methods and results. Mitigation measures will be recommended if the Project would produce adverse effects on any cultural resources found. Results The results of the cultural resources investigations will be presented in two reports: 1) a cultural resources background report; and 2) a summary Exhibit E document. These reports will be designed to meet FERC regulations set forth in 18 CFR 4.41. Draft copies of each report will be circulated for review, after which comments will be incorporated into the final reports. RECREATIONAL RESOURCES Purpose The purpose of the recreational resources study is to identify information regarding existing recreation use, future demand and opportunities, and the potential impacts on recreation resulting from development of the Mahoney Lake Project. This information, together with results of consultations with affected agencies and other interested parties, will be presented in a written Recreation Resources Report for inclusion in the Exhibit E of the Project’s License Application. Methods Agencies will be consulted and existing information will be collected. Development of the Recreation Plan will include three phases. Phase I will identify the current recreation types and existing facilities. Phase II will include the evaluation of existing and future recreation demands in the Project area. Phase III will identify the potential impacts created by the Project on recreation and will evaluate alternatives, recommend mitigation and provide costs, if necessary. Study Tasks Phase I - Evaluation of Existing Recreation Resources Data Collection. The area in which the Project will have an impact will be identified and existing information will be collected. Data to be collected include maps; recreation guides; the USFS Recreation Resource Information System, Recreation Opportunity Spectrum, and the Tongass National Forest Plan; and other sources of recreation information, such as state agencies. Information regarding demographic use will also be gathered. Consultation. Consultations will be held with the agencies who are responsible for recreation planning and management within the Project impact area. Current direction and policies for these agencies will be determined. Other agencies and native organizations which might track or project recreation use in the area such as local, county, and state administering agencies, will be contacted. Special-interest groups, local residents, and businesses that focus on recreation and tourism will also be consulted. Identify and Map Existing Facilities. From data collected, existing recreation facilities will be mapped for the Project area. Any National Wild and Scenic Rivers systems, National Trail systems, and Wildemess areas within the Project area will be identified. Phase II - Evaluate Recreation Demand Evaluate Recreation Potential. Existing recreation facilities in terms of activity type, physical setting, experience required, economic costs, and current demand will be evaluated. Future recreation use within the Project area will be identified and evaluated. Estimate Demand. Anticipated recreation demand with and without the proposed Project modifications will be estimated using demographic data. The demand projections will be correlated to regional opportunities for similar recreation. Constraints on development of recreation facilities will be identified. Phase III - Evaluate Project Impacts on Existing and Future Recreation Project Impacts. Potential environmental, social, and economic impacts created by the Project Tegarding existing and future recreation in the Project area will be identified. Alternatives will be identified based on data collected, associated impacts, constraints, and demand projections. If appropriate, mitigation measures will be recommended if it is determined the Project will produce adverse effects. Costs will be estimated for any new facilities and transportation access, plus operation and maintenance costs. Consultation. Agencies, native organizations, and special-interest groups who focus on recreation and tourism will be consulted regarding potential Project impacts. Results The data, maps, and study objectives information will be presented in a draft report and shared with the agencies of record for their comments. After review, any appropriate adjustments to the draft will be incorporated into the final report. The format for the reports will be in conformance with the requirements of FERC License Applications, Exhibit E (18 CFR 4.41). AESTHETIC RESOURCES Purpose The primary purpose of the aesthetics study is to describe measures proposed by the Applicant to make Project facilities blend, to the extent possible with the surrounding environment, and to evaluate aesthetic impacts of proposed changes in stream flow. Inventory and effects assessment activities will be conducted in order to identify and support any proposals for aesthetic treatments of Project facilities. Methods The aesthetics study will evaluate existing visual conditions, assess Project effects, and identify potential mitigation measures. Existing Visual Conditions A summary of existing visual conditions that addresses both Project facilities and the adjacent landscape will be addressed. Existing visual resource data related to the Project area, including the USFS Visual Management System, will be reviewed. Landscape character of the Project area will also be described. eT Project will be identified. Project Effects Assessment The effects of the proposed Project facilities on visual quality will be determined and presented in the report. This discussion will address the visibility of Project features from the selected viewpoints and will evaluate these views within the local visual context. The primary focus of this assessment will be impacts of reduced water flows over the waterfalls between Upper and Lower Mahoney Lakes and the impact of Project roads and powerhouse construction. Proposed Aesthetic Measures Potential measures that will reduce the visual contrast of Project features with the surrounding environment will be identified and their feasibility will be reviewed. Results The results of the aesthetics study will be presented in the Aesthetic Resources Report of Exhibit E. A draft report will be prepared and distributed to agencies of record for their comments. After their review and comment, a final report incorporating comments will be prepared. The aesthetics report will be formatted as required under FERC regulations (18 CFR 4.41). LAND USE . Purpose The purpose of this study is to determine existing uses of the proposed project lands and adjacent property, and those land uses which could occur if the project is constructed. This study will also determine the Project's compatibility with existing land uses and comprehensive plans. Methods Agencies will be consulted and existing land use maps, plans and policies will be collected. Existing Land Use and Ownership Existing land use and ownership will be identified. Identification of wetlands, floodlands, prime or unique farmland as designated by the U.S. Department of Agriculture Soil Conservation Service, and lands owned or subject to control by government agencies will be identified. Proposed New Land Uses Areas affected by the proposed project will be determined. Compatibility of Existing and Proposed Uses Land use plans and policies for the project area will be reviewed to determine existing and future land management within the project area and to determine the project’s compatibility with these plans and policies. EROSION AND SEDIMENT CONTROL PLAN Purpose The purpose of the erosion and sediment control studies is to evaluate the potential for erosion and sedimentation during proposed Project construction and operation. Based on this evaluation, an Erosion and Sediment Control Plan (ESCP) will be developed to provide guidelines for controlling erosion and sedimentation during Project construction and operation activities. Since most of the Project features are underground, the ESCP will concentrate on access roads and Methods The ESCP will establish baseline conditions in order to assess potential impacts and allow comparison with conditions during Project construction and operational phases; identify existing environmental hazards which must be taken into account during Project design, construction, and operation; and identify measures which will minimize potential adverse impacts. Agencies to be Consulted USFWS NMFS USFS COE ADNR ADFG Tasks The following tasks will be performed in order to prepare the ESCP: ite Existing site conditions will be evaluated including climate, topography, geology, soils, vegetation, surface and groundwater drainage, adjacent waterways, and hazard areas. 2. Erosion/sedimentation potential during construction of Project features and during Project operation will be determined. 3. Estimates will be made on the amount of tunnel spoils and locations for disposal sites will be identified. 10 4. Timing of construction activities will be identified and evaluated in terms of alleviating during Project construction and operation will be identified, mapped, and detailed drawings and descriptions of such measures will be prepared. 6. Implementation guidelines for general and site specific erosion control measures will be developed. ds A revegetation plan for disturbed areas will be developed. 8. Procedures for maintenance and monitoring of erosion control measures for plan modifications will be developed. 9. Using existing information from geologic reports, mapping, aerial photos or other sources, a qualitative review of the Mahoney Lake drainage basin will be made which will provide a general characterization of sources and types of sediment inputs into the river. The Universal Soil Loss Equation or another acceptable method may be used to estimate sediment delivery to Lower Mahoney Lake. To the extent feasible, (given the dynamics of the system), the relationship between geomorphic processes, Project operation, and sediment delivery will be characterized and discussed. Results A Draft ESCP will be prepared that details the Project area geology and soils, and characteristics of the Project segments. This report will include maps that illustrate the geologic and geomorphic conditions of the Project area. Upon completion, the report will be circulated to the appropriate agencies for comment and review. Following any necessary revisions, the report will be finalized and included as an appendix of the License Application. 11 MAHONEY LAKE HYDROELECTRIC PROJECT FERC NO. 11393 APRIL 26, 1994 JOINT AGENCY/NATIVE AMERICAN/PUBLIC MEETINGS SIGN-IN SHEET fae tans [ere uaa ear Stes Helos Tae esta Jove Treen [= — | inten [ewe [enw | | — | idsdelaaes — [oo¥-o07 [yn [RRO fie oe fea — 1 Balding 320 Occk Sh ADE] | ee et pons ee cinina Pie basen | [ oer ira a ram HLEM, — He H36I3 ] MAHONEY LAKE HYDROELECTRIC PROJECT FERC NO. 11393 APRIL 26, 1994 JOINT AGENCY/NATIVE AMERICAN/PUBLIC MEETINGS SIGN-IN SHEET LH | cbAvan (Ct 2p br 57 eatin : h Y =~ : | : ¥ | Q NAB I iS 7 y 4 y a Es - candidate animal species may occur in the proposed project area: marbled murrelet Brachyramphus maxmoratus Category 2 northern goshawk Accipiter gentilis Category 2 harlequin duck Histrionicus histrionicus Category 2 Two Category 2 plant species may occur in southeast Alaska. They are Calamagrostis crassiglumis, and Carex lenticularis var. dolia. If you have an questions about these comments or other endangered species issues, please contact John Lindell at this office. These comments are offered for endangered and threatened species for which the U.S. Fish and Wildlife Service has responsibility under Section 7 of the Endangered Species Act of 1973 (16 U.S.C. 1521 et seg.) and its amendments. The above comments are specific to the Endangered Species Act and do not . reflect agency concerns regarding other organisms-or-habitats for which the Service has legislated responsibilities. : Sincerely, ohn Lindell Endangered Species Biologist Mahoney.ed do Giy June 30, 1994 Ms. Teresa Trulock U.S. Forest Service Federal Building Ketchikan, AK 99901 Re: Mahoney Lake Hydroelectric Project FERC No. 11393-Field Studies Dear Ms. Trulock: This letter is to clarify the proposed studies for the above-referenced project and to answer questions raised in Steve Segovia’s letter dated June 21, 1994. Geotechnical Data As stated in the Initial Consultation Document that was distributed to the USFS on March 16, 1994, an erosion and sediment control study is proposed to take place this summer to evaluate the potential for erosion and sedimentation during the construction and operational phases of the project. Because most of the project features are underground, emphasis of the study will concentrate on the access road and potential tunnel spoils disposal sites. The access road is located on lands owned by the Cape Fox Corporation. Most of the tunnel spoils disposal sites will be on Cape Fox lands, but one is likely to be on National Forest System lands. The - proposed access road route will be flagged and surveyed up to the powerhouse location to visually identify any existing environmental hazards which could affect the design, construction, and operation of the project. No test drillings, earth-disturbing activities, or geophysical testing (seismic or drilling) will be done. However, after the license is issued by the FERC, it may be desirable to conduct some geotechnical drilling. A new application to perform that work will be submitted to the USFS at that time. Cultural Resources Chris Campbell of Cultural Resources Contracting, Inc. will conduct the cultural resources survey for the project. The permit application to conduct archaeological investigations on National Forest System lands has been forwarded to Ms. Campbell to complete and submit to the USFS. Like the anticipated approach for the erosion and sediment control study, the access road will be walked to the powerhouse location to visually identify any geomorphic features that could result in the discovery of potential cultural materials. No ground-disturbing activities or archaeological explorations will be done. The work is primarily to identify cultural resources and the project’s potential impacts on them. HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 Ms. Teresa Trulock U.S. Forest Service June 30, 1994 Page 2 Spach Tine Fermi The only study equipment to be placed on National Forest System lands is a water temperature monitor near the proposed intake in Upper Mahoney Lake. The monitor consists of a cable suspended in the lake down to a depth of 80 feet and connected to a waterproof box along the shoreline. The box is about one cubic foot in size. Other study work for the project that will occur on National Forest System lands will consist of hiking, photographing, and observations. There will be no ground-disturbing activities or tree cutting. Fish Wildlife The direct, indirect and cumulative effects of the project on downstream fish populations and the mountain goat population will be addressed in the FERC license application. A bald eagle nest survey will also be conducted. We hope this resolves any concerns the USFS has about the planned studies for the Mahoney Lake Hydroelectric Project. Because of the limited disturbance expected from these studies, we request that the requirement for an Investigative Special Use Permit be waived. If this requirement cannot be waived, we request this permit be issued as soon as possible to allow our planned studies to proceed. Please notify us of your decision on this matter as soon as possible. Thank you for your cooperation. Please contact me or Jack Snyder if you have any further questions. Sincerely, HDR ENGINEERING, INC. ~ WU Hove Michael V. Stimac Manager, Licensing & Environmental Services ce. Doug Campbell, Cape Fox Emesta Ballard, Cape Fox Veronica Slajer, City of Saxman Jack Snyder, HDR Debby Howe, HDR Lisa Fortney, HDR Mark Dalton, HDR HDR File, B.4.1 WAY 2 4 199 May 20, 1994 Mr. Michael V. Stimac Manager, Licensing & Environmental Services HDR Engineering, Inc. Suite 1200 500 108th Avenue, N.E. Bellevue, WA 98004-5538 Dear Mr. Stimac: Thank you for sending me a copy of the minutes from the April 26 meetings for the Mahoney Lake Project. I had hoped to attend, but was unable to fit it into my schedule. As I have expressed in the past, Iam a strong supporter of this and similar projects. Moreover, I do not see a conflict between these projects and transmission lines. Rather, they go hand-in-hand. Transmission lines enable possibilities we would otherwise be unable to consider. For instance, by connecting load centers, we not only can consider larger projects with better economics, we are able to consider projects which are located within the entire region. Without the transmission lines, we are forced to consider only those projects which are located near each load center--projects which are smaller, which have greater limitations, and which have higher unit costs. Please continue to keep me on your mailing list. Iam enclosing a paper which was prepared by Kake Mayor Lonnie Anderson and myself. General Manager SOUTHEAST ELECTRICAL TRANSMISSION INTERTIE SYSTEM The vision and long range goal of the community leaders responsible for energy is to connect the major communities in Southeast Alaska to a backbone transmission intertie system running from Whitehorse/Carcross in the Yukon to Skagway, Haines, Juneau, Sitka, Petersburg, Wrangell and Ketchikan. Those communities would further be connected to the continental grid system either at Prince Rupert or Stewart, B.C. Branches from the backbone would serve Greens Creek, Hoonah, Tenakee and Angoon. A connection from Sitka to Petersburg would also serve Kake. A line from Ketchikan would connect to communities on Prince of Wales Island, and a shorter line would add Metlakatla. Mineral developments in Berners Bay, Greens Creek and Juneau would benefit. Large minerals deposits at Quartz Hill near Ketchikan and Windy Craggy in the Yukon near Haines would have their long- range development efforts enhanced by the availability of large quantities of low-cost energy. Other Canadian mineral developments on the east side of the coast range, from Tulsequah on the Taku River to Johnny Mountain on the Iskut River, would also be connected. Promising mineral finds on Native-owned lands on Prince of Wales Island would be much more feasible for development. As large loads are connected and transmission lines constructed, many hydroelectric projects which lack the necessary size to justify construction will become feasible. Some of these projects are Lake Dorothy and Speel River near Juneau, West Creek near Skagway, Chilkat Gorge above Haines, Lake Takatz near Sitka, Swan and Scenery Lakes in Thomas Bay near Petersburg, and Lake Grace and Mahoney Lake near Ketchikan. _A fundamental benefit of an interconnected system is that individual power and economic development projects would be evaluated on the basis of their worth to the entire system--not just to the local area. In other words, the entire region would be helping to pay for the new projects. Thus, only the best of the projects would be developed. Today, there is a limited amount of state funding. Thus, it is crucial to get maximum benefit from those limited funds to obtain maximum leverage for future projects. Each increment of the overall transmission system would help to justify future projects, and each project would increase the number of consumers who benefit. The more consumers there are, the easier it is to achieve feasibility on any given project. Moreover, as the region grows, construction of transmission interties will be determined not only by the need to connect a community, but also by the need to reach a new hydroelectric source. In the immediate future, there are two possible interties: Tyee-Swan Lake, for which feasibility work has already been completed, and Petersburg-Snettisham, where feasibility work has not yet started. The former project will make needed capacity available to Ketchikan, but the feasibility analysis indicates that only in the "high growth" scenario would significant amounts of energy flow from the Tyee project to Ketchikan. Both the low and medium growth scenarios indicate little or no energy flow from Tyee to Ketchikan, and it is energy flow which would add the revenue necessary to pay for the project.. In short, the analysis indicates a marginal project at best. Juneau currently has a very large load, but also has a surplus of generating capacity and energy available at Snettisham. If an intertie is built, several advantages are immediately available. First, the capacity and energy would be available to backfeed to Petersburg so that needed repairs could be made to the Tyee line without interruption of service. Second, the line would be built close to or through Kake, so that an extension to Takatz--and Sitka--could subsequently be made in the future. Finally, development of the A-J Mine in Juneau will create a substantial demand for both capacity and energy--up to 275 million kWh of energy per year. There are 90 million kWh of excess energy available at Tyee, 86 million kWh (firm and non-firm) energy available from Snettisham. The A-J Mine will construct its own generation capacity, of up to 24 megawatts (MW) in combined-cycle turbines and hydroelectric power, but will want to use purchased power before using its own generation. Thus, all of the energy from Tyee can be used. This would end the subsidization of Tyee power by the other Four Dam Pool members and increase the revenue stream from Tyee by up to $5.8 million (at current rates). Besides Snettisham, other potential loads in the Juneau area are possible. If a line is constructed to Greens Creek, 5 to 10 MW will be needed, and 7 MW would be needed at the Kensington Mine in Berners Bay north of Juneau. As mineral deposits are developed in British Columbia, spur lines could be developed. If the Tyee-Swan line is built to Ketchikan, potential for connection to Prince of Wales Island communities is enhanced. These links make possible a connection both to BC Hydro at Stewart, BC (picking up the Quartz Hill Mine) or at Prince Rupert (using an underwater line), and to Yukon Energy through Haines and Skagway. nn KETCHIKAN GATEWAY BOROUGH Sed Department of Planning and Community Development * 344 Front Street » Ketchikan, Alaska 99901 ; Gary Mi ig Director filg Bum (907) 228-6610 15> 00! & May 20, 1994 Fax: (907) 247-8439 Michael V. Stimac HDR Engineering, Inc 500 108th Avenue, NE, Suite 1200 Bellevue, WA 98004-5538 SUBJECT: Mahoney Lake Hydroelectric Project I am in receipt of your recent transmittal regarding the consultation meetings in Ketchikan on April 26. I was unable to attend the entire briefing and apparently arrived at the Cape Fox Lodge session as the meeting was completed. The Department has no specific comments at this time. The Department is engaged in the process of updating the Coastal Zone (\) Management Plan which includes a required energy facilities element. The current draft recognizes the subject proposal and suggests ‘that the community support it as a part of an objective which seeks to meet the demand for affordable electric power. While proposed policies have not been subject to public review, I would anticipate that policies will be adopted during the course of the project study timeline. I would be pleased to share the a draft recommended plan with you or your associates when it becomes available later this summer. Please do not hesitate to contact me if you have any questions. Singere 7 wa, ary nsterman, AICP Plan se Director 3 ona Campbell, Cape fox Corporation Veronica Slajer, City of Saxman gm\planad\mM462-482 ee bo Z0.f a 7 ENR] Ae, ENVIRONMENT AND NATURAL RESOURCES INSTITUTE + UNIVERSITY OF ALASKA ANCHORAGE 707 A STREET ALASKA STATE CLIMATE CENTER 257-2737 ANCHORAGE ARCTIC ENVIRONMENTAL INFORMATION AND DATA CENTER 257-2733 ALASKA 99501 ALASKA NATURAL HERITAGE PROGRAM 279-4549 (907) 279-4523 FAX 276-6847 . -f May 21, 1994 Anne Leggett HDR Engineering, Inc. 2525 C Street, Suite 305 Anchorage, Alaska 99503 Dear Anne: I am writing in response to your request for information regarding Northern goshawk nest sites in the vicinity of Mahoney Lakes. Recent radiotelemetry studies of goshawks in southeastern Alaska have shown that the adult home range size during the brood-rearing period varies from 1,800 - 47,956 acres for males and 674 - 275,290 acres for females. The greatest distance from a nest travelled was 34 miles for a female and 19 miles for a male (ADFG 1993). Within this range (34 miles) 5 locations have been identified where goshawk nest could occur. These include Niblack Anchorage (POWI), Ketchikan Lakes (Revilla I.), Naha/Leask (Revilla), Hassler Pass (Revilla), and Vixen Inlet (Cleveland Peninsula). Of these sites, Ketchikan Lakes is the closest, being only 2 miles from Upper Mahoney Lake. Goshawks have also been observed at Herring Bay, north George Inlet, and Jordan Lake (all Revilla I.). These data indicate that goshawks do occur in the Mahoney Lakes area. No nest sites have been confirmed, however, within one mile of the area you outlined on your map. If there are substantial old growth forest stands in this area, it is possible a pair of birds could nest there. If this habitat is not present, they probably do use the area somewhat for foraging. I hope this information is useful to you. If you need additional information, or have any questions, just call. Sincerely, Af Lia” Edward W. West, Ph.D. Assist. Prof. Biology Alaska Natural Heritage Program ri mons FROM HDR ENGINEERING, INC. 06.18.1994 89:35 P. 2 JUN~ 9-94 THU 18149 KTH ¢ISh & GAME, HABITAT 98722-2676 P.81 MEMORANDUM _ STATE OF ALASKA alia : YiQr | Tor Faw na ~. Viens vorjeg DEPARTMENT OF FISH AND G ‘Stim Christine Valentine: : ' Dara June 3; , Project Coordinator ' os aaee Ye | Division of Governmental - Fria Now AK9603-3300: rOrmLey Coordination = A bhY¥ae ij Juneau Zh, Paons: «225-2037 -. MONQnrbe LenaChnes Susssct: Mahoney Lake H electric | ar Supervisor ‘Project, FERC Project i itat & Restoration No. 11393 Douglas ‘ | We have the following comments regarding the initial consultation phase for the Mahoney Lake Hydroelectric project. The Initial Consultation Document (ICD) and associated meetings did a good job in describing the scope and intent of the project. This will form the basis for completing thie project in an expeditious manner. Of particular concern will be acquiring additional information concerning changes in stream flows and water temperatures as a result of the project, This includes learning more about the stability of the flow regime which supplies the upwelling uciliced by sockeye salmon spawning along the western shoreline of the lake. It will be dmportant that the temperature and flow modeling and analysis be combined with the results of the fish studies in a manner that acourately predicts the effects that the project might have on fish productivity. ; We would also suggest more frequent monitoring of the Mahoney Lakes sockeye spawning cycle to more acourately determine the timing and abundance of this run. Otherwise, the site visit planned for September could potentially mise the peak spawnin period and result in inadequate data regarding the location o spawning and overall site productivity. Also, there may be uncataloged anadromous and/or resident fish tributaries in the vicinity which, if present, should be identified, The wildlife and botanical objectives during the review phase for this project, howaver, are more vague. One concern not mentioned, for example, might be the transmission line which goes from. Mahoney Lake to the Swan Lake corridor. The next phase of the project should describe the mitigative measures proposed to minimize potential collisions with large birds (such ag swans and geese utilising Mahoney Lake) or the electrocution of raptors. Additionally, we do not have a copy of the 1983 Co of Engineers DEIG referred to in the ICD. We would like to receive a copy of this for our files regarding this project. Thank you for the oppertunity te Post-tt™ brand fax tranemitial memo 7671 Tae ee —ehn Meareed feck Gusk Gon _| +*e END eee Jack Gustafson, ADFEG, Ktn Rruaa Jahnaan. ADNR, Inu Seo) June 3, 1994 : Mah | Julia Moore > Alaska Natural Heritage Program 707 A Street, Suite 208 Anchorage, AK 99501 Subject: | Mahoney Lake Hydroelectric Project - Information Search Dear Ms. Moore: HDR Engineering is assisting the City of Saxman and the Cape Fox Corporation in evaluation of a potential hydroelectric project near Ketchikan, Alaska. We are presently gathering existing information on the project area, and developing study plans to fill information gaps. Attached is a topographic map depicting the project area. The habitats which are likely to be affected by the hydroelectric project include: a lake (elevation 2000 feet); a west-facing steep mountain slope (elevation 2000’); a gravelly, alder-dominated riparian area (elevation 2000 feet); a cascading stream and waterfalls that flow eastward between elevation 2000 feet and sea level; and flat to east-facing old growth Sitka spruce-western hemlock forest and muskeg near sea level. I am interested in obtaining whatever information the Natural Heritage Program can provide on rare plant and animal species known to occur in the project area, as well as those with a fair probability of being in the area. It would be helpful if you could describe the habitat in which each species is likely to occur. (Julie Michaelson said this information would come from the EGR.) I would also like information on vegetation communities likely to be found in this area, as well as rare and unique plant communities. I have already consulted with Ed West regarding the presence of Queen Charlotte subspecies of goshawks in the Ketchikan area, so I do not need any more information on them. Thank you for your attention to this. Please call me if you have any questions. If, by chance, any of this information is ready by June 10, I would like to come pick it up, as it would be helpful to have it before I travel to the project site the following week. Sincerely, ‘Bure FR = Anne Leggett Enclosure ce: Mike Stimac, HDR Engineering, Bellevue HDR Engineering, Inc. 2525 C Street Telephone Suite 305 907 274-2000 Anchorage, Alaska Fax 99503-2689 907 274-2022 “4 aren to be cLireet ly atlreted N BS Rae map: USGS Ketzh ben ES quact . i : Mo Jer) Date Submittea: _“/3/4/ Date Information Needed: 7/! 144 Contact Person: Amnr< Leccet+ Title: Shit Bislecicx Organization: tip@ Ersines ee Te Program: Address: 2525 _ C Stre-7 Cy te 305 Am ch mae Ale 4950> Phone: _274- 2065 Fax: 734-762. E-mail: — Please fill out the above information; this will be used for future mailings concerning information requests. INFORMATION IXPE What type of information are you requesting (please be as specific as possible). see reverse side. Sec Fh a cg of vir Athy ee LOCATION (Please submit map with outline of area of concern) Legal Township & Range: 7.745 K.7/£. 6 KM. Section(s): MN LY 23-27% 29-36 USGS Map Name: _Acte4-ko~ C-3 Nearest Town or Locatable Landmark: << /<4- +: > INFORMATION APPLICATION For what project will the information be applied? (i.e. Rosie Creek research project, mine expansion, etc.) Zetomcy (ale Hu/vekme Lorie t How will the acquired information be applied? (i.e. EIS, management plan, etc.) Ave lyyig Starla lac’ fom phe Pr f-derat Lners 4 Kraula- hes 0; > 1SSt0n lipenc, 7h Crellon AS FLOP Mine n7 ard possbly (BES Dre pho n- Sn Hove ao Bu. June 3, 1994 ee Steve Zimmerman a Division Chief, Protected Resources Management National Marine Fisheries Service P.O. Box 21668 Juneau, AK 99802 Subject: Mahoney Lake Hydroelectric Project Dear Mr. Zimmerman: The City of Saxman, Alaska, is investigating the development of a 9.6 megawatt hydroelectric project at Mahoney Lake near Ketchikan, Alaska. The Federal Energy Regulatory Commission (FERC) issued a preliminary permit to the City of Saxman in June 1993 to allow them to study the project. Cape Fox Corporation, the village corporation for Saxman, is acting as the project’s development agent, and HDR Engineering, Inc. is providing engineering and environmental services. A brief project description is attached. We at HDR Engineering are presently updating our information on the project area’s natural resources and are preparing to conduct field studies. The purpose of this letter is to seek information you may have on species of federal concern that may be affected by this project and to initiate the consultation required under Section 7 of the Endangered Species Act. The information you provide will be used to prepare the FERC license application and National Environmental Policy Act documentation for the project. The project area is described in the attached description. Habitats in which the project will occur include old growth Sitka spruce- western hemlock forest, lowland muskeg, lakes, and a stream and its riparian zone. Please send me a list of threatened and endangered species that may be found in the project area, as well as other species under study for listing as threatened or endangered. Any information or references you could provide on habitats in which the species might be found and on activities that typically disturb these species would also be appreciated. Thank you for your attention to this. Please call me if you have any questions. Sincerely, HDR ENGINEERING, INC. Likes FAO Staff Biologist Enclosure cc: Mike Stimac, HDR Engineering, Bellevue HDR Engineering, Inc. 2525 C Street Telephone Suite 305 907 274-2000 Anchorage, Alaska Fax 99503-2689 907 274-2022 June 3, 1994 John Lindell, Endangered Species Coordinator he U. S. Fish and Wildlife Service 3000 Vintage Boulevard, Suite 201 Juneau, AK 99801 Subject: Mahoney Lake Hydroelectric Project Dear Mr. Lindell: Thank you for talking with me earlier this week about consultation required under Section 7 of the Endangered Species Act. The City of Saxman, Alaska, is investigating the development of a 9.6 megawatt hydroelectric project at Mahoney Lake near Ketchikan, Alaska. The Federal Energy Regulatory Commission (FERC) issued a preliminary permit to the City of Saxman in June 1993 to allow them to study the project. Cape Fox Corporation, the village corporation for Saxman, is acting as the project’s development agent, and HDR Engineering, Inc. is providing engineering and environmental services. A brief project description is attached. We at HDR Engineering are presently updating our information on the project area’s natural resources and are preparing to conduct field studies. The purpose of this letter is to seek information you may have on species of federal concern that may be affected by this project and to initiate the consultation required under Section 7 of the Endangered Species Act. The information you provide will be used to prepare the FERC license application and National Environmental Policy Act documentation for the project. The project area is described in the attached description. Habitats in which the project will occur include old growth Sitka spruce- western hemlock forest, lowland muskeg, lakes, and a stream and its riparian zone. Please send me a list of threatened and endangered species that may be found in the project area, as well as other species under study for listing as threatened or endangered. Any information or references you could provide on habitats in which the species might be found and on activities that typically disturb these species would also be appreciated. Thank you for your attention to this. Please call me if you have any questions. Sincerely, HDR ENGINEERING, INC. rina £eage Anne Leggett Staff Biologist Enclosure cc: Mike Stimac, HDR Engineering, Bellevue HDR Engineering, Inc. 2525 C Street Telephone Suite 305 907 274-2000 Anchorage, Alaska Fax 99503-2689 907 274-2022 Mahoney Lake Hydroelectric Project Description June 2, 1994 The City of Saxman, Alaska, is investigating the development of a 9.6 megawatt hydroelectric generating plant located at Mahoney Lake near Ketchikan, Alaska. The proposed Mahoney Lake Hydroelectric Project is located five miles northeast of Ketchikan on lands owned by the Cape Fox Corporation (Saxman’s native village corporation) and the U.S. Forest Service. The proposed project will use a lake tap - a tunnel into Upper Mahoney Lake about 75 feet below its surface - and a series of tunnels to convey water from Upper Mahoney Lake to the powerhouse located near Lower Mahoney Lake. No dam will be constructed. The normal water surface elevation of Upper Mahoney Lake is 1,959 feet. The turbine in the powerhouse will be set at elevation 150 feet, thereby providing a gross head differential of 1,809 feet. The project area is shown on the attached sketch map. The uppermost tunnel, which will tap into the lake, will be about 1,480 feet in length from the lake to where it surfaces in a flat riparian area about 1,500 feet downstream of the upper lake. A valve house will be constructed at this site containing a vent pipe, the primary intake shut-off valve, and the emergency shut-off valve. Downstream of the valve house, a 1,370-foot-long vertical shaft will be constructed to house the steel pipe that will convey water to the powerhouse. The powerhouse will be a semi-underground structure constructed at the portal entrance to the lower tunnel. It will contain a single twin-jet horizontal Pelton turbine. Maximum rated discharge will be 78 cfs and rated net head will be 1,730 feet. The synchronous generator will generate at 13,200 volts and be rated 9,600 kW continuous. The powerhouse site has been selected to avoid potential impacts to fish using Mahoney Creek. The cascades and waterfalls between the upper and lower lakes end at a deep pool surrounded by bedrock walls at approximate elevation 140 feet about 8,000 feet upstream of Lower Mahoney Lake. The water discharged from the proposed turbine will re-enter Mahoney Creek at this pool. Fish cannot ascend the cascades upstream of this point on Mahoney Creek. The transmission line route will begin at the powerhouse and follow along the south and east sides of Mahoney Lake, then run northward to its connection with the 115 kV Swan Lake transmission line near the confluence of the White River with George Inlet. A switchyard will be located 0.8 miles from the powerhouse along this route. A power transformer will be located in the switchyard to step up generation voltage from 13.2 kV to the transmission voltage of 115 kV. The transmission line will include 0.8 miles of 13.2 kV underground cable at the powerhouse end and 4.7 miles of 115 kV overhead cable. The 115 kV transmission line will follow along an existing logging access road recently constructed by the Cape Fox Corporation. A new access road will be constructed to connect the existing road and the powerhouse site. vady 124 LS0%d any RW ALINIDIA (-xovaew) Ww T dVW ALINIOI . 4939 ASNOMYW O | \ 99992 Ager \ op avoy Sosa merase WY @ x \ WALTER J. HICKEL, G OR Es - - H ox Bl x Shade. 3601 C STREET, Suite 1278 a JOVwW DEPARTMENT OF NATURAL RESOURCES ST RaT Rae "Oy abe. amputtt, DIVISION OF PARKS AND OUTDOOR RECREATION MAILING ADDRESS: P.O. Box 107001 Office of History and Archaeology ANCHORAGE, ALASKA eer Male} June 8, 1994 yoct File No.: 3130-1R FERC Subject: Project No. 11393, Mahoney Lake Hydro Initial Consultation meeting minutes Michael V. Stimac, Manager Licensing & Environmental Services HDR Engineering, Inc. Suite 1200 500 108th Ave., N.E. Bellevue, WA 98004-5538 Dear Mr. Stimac; Thank you for the meeting minutes and Licensing Study Plans for the referenced project. It is our opinion that the study tasks () described on pgs. 6-7 will be adequate to identify any significant historic and archaeological resources in the area of potential effect of the project. We look forward to reading Cultural Resources Consulting’s Assessment Report on historic properties when available. Please contact Tim Smith at (907) 762-2625 if there are any questions or if we can be of further assistance. Sincerel Bittne ] State Historje Preservation Officer JEB:tas ne 7 Campi United States Department of the Interior 4% FISH AND WILDLIFE SERVICE SHmic Southeast Alaska Ecological Services i 3000 Vintage Blvd., Suite 201 Bahl, Juneau, Alaska 99801-7100 IN REPLY REFER TO: ‘Drtnee Al 64 2/8. saps lbnanes June 9, 1994 Mr. Michael V. Stimac HDR Engineering, Inc. 500 108th Avenue, N.E. Suite 1200 Bellevue, Washington 98004-5538 RE: Mahoney Lake Hydroelectric Project, FERC No. 11393 Dear Mr. Stimac: The U.S. Fish and Wildlife Service has reviewed the documents furnished by your office on the subject project. We find the current project more environmentally benign than the earlier proposals. The proposed studies should provide the data needed to address the issues not yet answered. The water quality and quantity study is of particular interest. Water temperature differences (\) between the penstock intake in upper Mahoney Lake and the upwelling areas used by spawning sockeye salmon in lower Mahoney Lake are necessary to determine project effects on spawning salmon. We look forward to reviewing those studies. The Eagle Protection Act (16 USC 668-668d) prohibits molesting or disturbing bald eagles, their nests, eggs, or young. Our 1982 ® Coordination Act Report recommended the above ground transmission line be located more than 1/8 mile from the shoreline. We encourage the actual routing of the transmission line follow that recommendation if at all possible. We appreciate the opportunity to comment. Sincerely, Nevin D. Holmberg Field Supervisor June 15, 1994 Mr. Jack Gustafson Alaska Department of Fish & Game Habitat Division 2030 Sea Level Drive Room 205 Ketchikan, AK 99901 Re: Mahoney Lake Hydroelectric Project FERC No. 11393 Dear Mr. Gustafson: We have received a copy of the June 3, 1994 memorandum from Lana Shea of Alaska Department of Fish and Game to Christine Valentine of Alaska Division of Governmental Coordination with comments relating to the Mahoney Lake Hydroelectric Project. These comments are very much appreciated and will be incorporated into the Final Consultation Document that will be distributed in July. Enclosed is the 1983 Corps of Engineers DEIS which was requested in that memorandum. Thank you for your participation in this project. Please contact me if you have any questions regarding the Mahoney Lake Project. Sincerely, HDR ENGINEERING, INC. Micha’ V. Shae (Lot Michael V. Stimac Manager, Licensing & Environmental Services cc. D. Campbell, Cape Fox E. Ballard, Cape Fox V. Slajer, Saxman J. Snyder, HDR HDR File, B.4.1 /e20—- HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 RECEIVED IN ANCHORAGE e National Marine Fisheries Service Gnudle JUN 20 994 P.O. Box 21668 a Juneau, Alaska 99802-1668 Hwy a: HDR ENGINEERING, INC. SCT Ba at & Ms. Anne Leggett HDR Engineering, Inc. 2525 C Street Suite 305 Anchorage, Alaska 99503-26€89 Dear Ms. Legget: - We have received your letter of June 3, 1994, requesting a list of species in the Mahoney Lakes project area which are subject to consultation with the National Marine Fisheries Service (NMFS) under Section 7 of the Endangered Species Act (16 U.S.C. 1531 et seq). We have indicated the listed species which can occur in the general geographic area, but caution that these species may not occur in the immediate project area. Endangered Species: humpback whale (Megaptera novaeangliae) Snake River sockeye salmon (Qnchorhynchus nerka) gray whale (Eschrichtius robustus) . Threatened Species: Steller sea lion (Eumetopias jubatus) Snake River spring/summer chinook salmon (Onchorhynchus tshawytscha) Snake River fall chinook salmon (Onchorynchus tshawytscha) Work not involving marine waters is unlikely to-affect these species, but if you suspect interactions, you must provide a description of the project and your determination as to the mature and extent of the action’s impacts on listed species. NMFS jurisdiction is generally limited to marine species, and we have not included terrestrial and other aquatic species under the jurisdiction of the U. S. Fish and Wildlife Service. You should contact that agency directly for this information. Sincerely, Orb ee, Tamra L. Faris . Southeast Alaska Office Supervisor am GS x — UNITED STATES DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Agpipetetion A/ai2 June 21, 1994 Ms. Teresa Trulock U.S. Forest Service Federal Building Ketchikan, AK 99901 Re: Mahoney Lake Hydroelectric Project FERC No. 11393 Dear Ms. Trulock: As requested in your conversation with Jack Snyder last week, enclosed are copies from the 1983 Draft Interim Feasibility Report and Environmental Impact Statement (DEIS) relating to the Mahoney Lake Hydropower Project as proposed by the U.S. Army Corps of Engineers. We do not have a copy of the actual cultural resources assessment referred to in the DEIS and are in the process of tracking it down. If we are able to obtain a copy, we will have an extra made and will forward it to you at that time. Please contact me if you have any further questions. Sincerely, HDR ENGINEERING, INC. Michael V. Stimac Manager, Licensing & Environmental Services Enclosures cc. Doug Campbell, Cape Fox Emesta Ballard, Cape Fox Veronica Slajer, City of Saxman Jack Snyder, HDR Debby Howe, HDR Lisa Fortney, HDR Mark Dalton, HDR HDR File, B.4.1/2Q HDR Engineering, Inc. Suite 1200 Telephone 500 108th Avenue, N.E. 206 453-1523 Bellevue, Washington 98004-5538 — wetland. Selective removal of trees may be necessary on approximately 75 additional acres. Wildlife--While some displacement of resident wildlife would occur during construction, the project would not result in significant losses of habitat. Fisheries--The status of most fish species in the Mahoney Lakes system would not be affected by the project. However, sockeye salmon that now spawn along the western shore of the lower lake would be adversely affected by project related discharges of 4°C water. Water Quality--Major impacts to water quality of the Mahoney Lakes system are not anticipated. Socioeconomic and Esthetic Resources--Slight social and economic growth in the Ketchikan area may occur during project construction. Ketchikan would benefit from the project by the availability of lower cost energy. Drawdown of Upper Mahoney Lake would result in the loss of a spectacular waterfall. Sites near the proposed project site. 3.2 Alternative Features [ x Cultural Resources--There are no significant historic or archaeological Coastal Forest, Wetlands, and Wildlife--Substantially greater acreages of forest (also including alpine areas), and to a lesser extent wetland, would be destroyed or altered by: 1) construction of a road from Beaver Falls to the project site, 2) construction of a road to the penstock tunnel portal, and 3) construction of a taller dam at the outlet of the upper lake to Provide greater storage capabilities. Negative impacts to forest and wetland ecosystems and losses of wildlife habitat would be much more significant if these alternatives are selected over the recommended plan. Impacts to forests, wetlands, and wildlife resources from other alternative features would not be significantly different than impacts associated with the recommended plan. Fisheries--Effects of alternative features on fish would be negligible, or similar to the effects of recommended features. An alternative tailrace design that would include artificial spawning beds could potentially improve fish production in the lower lake. — Water Quality, Socioeconomic, Esthetic, and Cultural Resources--Alternative feature impacts to these four resources would be similar to potential effects of recommended features. However, a road connecting Beaver Falls to the project site would adversely affect water quality and esthetic values to a greater extent than the recommended plan. 3.3 No Action If the proposed project is not constructed, the condition of existing resources near the Mahoney Lakes system would not change. EIS-6 lake. During ti. “spring, Upper Mahoney Creek ¥ wa. found: to eoatatn 12 mg/1 of -dissolved oxygen. Mahoney: Lake is known to have similarly high levels of dissolved oxygen. . , "Water ‘temperatures in ‘the’ system fluctuate from just above orc in the _winter to .10 to 12°C near the surfaces of the lakes in the summer. The temperatures in Upper Mahoney and Mahoney Creeks reflect the surface temperatures of the lakes they drain.. Normal patterns of temperature stratification occur in the lakes. Further information on temperature ‘stratification can be found ina subsequent section dealing with Project impacts to fish. Sedimentation and turbidity are. not significant problems: in the Mahoney -Lakes system. Despite heavy rainfall, steep ‘slopes, and ‘dynamic flow regimes in the streams, erosion is minimal due. to coarse textured soils with thick surface. organic: layers, - ‘high infiltration rates, and conditions that favor rapid revegetation. - at in general, water quality in the Mahoney Lakes system is high. There is no evidence of any chemical contamination or other manmade pollution. 4.2.6 Socioeconomic and. Esthetic Resources The nearest city to the project sité, Ketchikan, is about.6 miles from the site. Approximately 10,000 to 15,000 people,. including. most of the population of Revillagigedo Island, live in the Ketchikan Borough, depending on the season. Main industries are commercial fishing and forest Products. Social and economic growth in the area is slow. Very little social or economic significance is associated with the Mahoney Lakes system _in its present state. Additional socioeconomic information can be obtained _ by referring to the environmental conditions section and the main report. The Mahoney Lakes system contains a spectacular. 100- foot waterfall between the upper and lower lakes. Waterfalls are generally regarded as having high esthetic value and the Upper Mahoney Falls is no exception. A good .view of it can be obtained by boat from George Inlet. In addition, the | natural environment around Mahoney Lakes shows no sign of human - disturbance, further enhancing the. esthetic values associated with the area. 4.2.7 Cultural Resources Cultural resources on Revillagigedo Island have not been investigated in. detail. . Tlingit Indians used the: area near present day Ketchikan for fish camps and a village was located in the vicinity. George Inlet was used for hunting and fishing, but no permanent villages were located there. Widespread settlement by native groups probably. was precluded jin many areas by the steep, sic babel terrain of the island. . 5.0 ENVIRONMENTAL EFFECTS In the tentatively recommended plan, an estimated 18 acres adjacent to the lower lake would be altered due to construction of the penstock, powerhouse, tailrace, road, transmission line, and camp area. Land adjacent to the EIS-13 the lower lake would not be great enough for supersaturation to occur. Project impacts to water temperature regimes would also not.be significant except-in a highly localized area along the west shore of the lower lake. An analysis. of project related water temperature changes: Was presented in- the previous section dealing with impacts to fish. ' The disposal of an estimated 37, 000 cy ‘of excavated material (derived from the penstock tunnel. and discharge. road) ‘on slopes’ adjacent to the tunnel Portal. may increase sedimentation and turbidity levels in the lower lake. Much of the excavated material is: expected to be large rock, however, which should help to minimize the sediment load derived from ‘tailings. In. many cases, reservoir drawdown can result in severe erosion along exposed banks and increase turbidity levels. This is not expected to be a significant Problem in Upper Mahoney. Lake. Much of the area that would be exposed is bedrock or large material that would. not be susceptible to erosion. Construction of various recommended or alternative features may cause erosion and the resulting sedimentation of lakes and streams. The use of appropriate control measures should prevent serious damage to aquatic systems. Barge docking and seaplane activity may adversely affect water quality in George Inlet. Conditions should improve, however, as traffic . diminishes after construction has ended. . The road alternative from Beaver Falls:to the site would be subject to severe erosion due to the stee : slopes. Water quality problems associated with this alternative would be more San ese than impacts associated with the recommended form of site access. 5.6 Soc ioeconomic and Esthetic Resources A benefit of: the Mahoney Lakes hydropower project would be the availability of lower cost electrical energy to Ketchikan area consumers. Stimulation of social or economic growth ‘in the community ‘is not an objective. The ‘purpose of the proposed project is to supplement the projected energy demand for Ketchikan. However, slight social and ecomonic growth in © Ketchikan may be associated with the construction Phases of the proposal due to an influx of workers and their families. i Implementation of the Soneeal would result in the..loss of the waterfall on Upper Mahoney Creek. The relative esthetic value of the falls is difficult to measure since the number of visits by people to within viewing range is unknown. Most viewing of the falls is probably incidental to other : activities such as sport fishing. Therefore, the significance of this loss is not readily apparent. In general, the proposed project would diminish the esthetic value for those who etry an undisturbed ‘natural environment as appealing or desirable . 5.7 Cultural Resources The proposed project would have no impacts on cultural:resources. No known National Register sites are located in the vicinity. An intensive professional cultural resources survey of the project area located no significant historical or archaeological sites (Steele, 1981). EIS-23 8.0 LIST OF PREPARERS The following: people were primarily responsible for preparing this : CG draft. EIS: : ok : o1) 2 a 17 ile 5 Name .: _. Discipline > /*__ Experience "Role in Preparing EIS Mr. Richard A. Weide Wildlife Biologist ‘6 months, bio. tech., EIS coordinator: and yl : a. ..° U.S. Fish and Wildlife principal preparer. - Service. 1 year, bio. — tech., Corps of Engineers. 1-1/2 years wildlife , biologist, Corps of | Engineers. Ms. Julia Steele - . Archaeology 1. year, graduate field Prepared cultural *K Le les , . work in. Alaska and _resources sections , New York. 1 year, of EIS. archaeologist, Dept. of Interior. 3 years, archaeologist, Corps of Engineers. Mr. Harlan Legare ; Hydraulic Engineering 3 years, engineering Plan formulation , consultant, E.A. Hickok and development of and Assoc. 2 years alternatives. hydraulic engineer, Bureau of Indian Affairs. 2 years, project manager, Corps of Engineers. oo EIS-26 Olendorff, R.R., A.D. Milier,: and R.N. Lehman. 1981. Suggested practices for raptor protection on power lines - The state of the art in 1981. Raptor Research Rep. -No. 4. Raptor Research Found., .Inc. Dept. = Veterinary Biology, Univ.: of. Minn., St. Paul, Minnesota. Olson, S.T. 1979. The ‘life and: times of the black-tailed deer in southeast Alaska. p.160-168 in 0.C. Wallmo and J.W. Schoen (eds.). Sitka black-taited deer: Proceedings of a conference in Juneau, Alaska. Series No. R10-48. USDA, Forest Service and Alaska Department of Fish and Game. Sheridan, W.L. 1962. Relation. of stream temperatures to timing of pink salmon escapements in southeast Alaska. p. 87-102 in N.J. Wilimovsky, (ed.). Symposium on pink salmon. -H.R. MacMillan Lectures in Fisheries, 1960. University of British Columbia., Vancouver, B.C. * Steele, J. 1981. Cultural resoures assessment for Mahoney Lakes hydropower project. U.S. Army Corps of Engineers, Anchorage, Alaska. Teshmont Consultants Inc. 1982. Reconnaissance design and cost estimate of submarine DC electric power transmission system in southeast Alaska. Task D Report, Vol. 1. Prepared for U.S. Dept. of Energy, Alaska Power Administration. Wallmo, 0.C. 1978. Mule and black-tailed deer. p.31-41 in J.L. Schmidt and O.L. Gilbert (eds.). Big game of North America: Ecology and management. Wildlife Management Institute Stackpole Books, Harrisburg, Pennsylvania. Zach, L.W. 1950. A northern climax, forest or muskeg? Ecology 31 (2): 304-306. : : EIS-29 -€& “ED STATES DEPARTMENT or AGRICULTL.. FOREST SERVICE P.O. Box 1628, Juneau, Alaska 99802 2360 unu ye Wt - oe Mr. George R. Robertson District Engineer Corps of Engineers P. 0. Box 7002 : - Anchorage, Alaska --99510 Dear Mr. Robertson: The following is in reference to NPAEN-PR-R, letter of November 18, requesting preliminary historical/archeological report for three potential hydroelectric sites near Ketchikan, Alaska. a. Lake Grace: No historic/archeological sites are presently known in this vicinity; however, the vicinity of the dock and work camp have a high potential in view of the salmon runs in Grace Creek and the estuarine nature of the mouth of the creek. The inland areas of the transmission line to Carroll Inlet have low potential. b. Swan Lake: No historic/archeological sites are presently known in the near vicinity of the lake, powerhouse, and transmission line to the point of crossing Carroll Inlet. Potential for historic/archeological materials in these areas is judged to be low. The transmission line from Nigelius Pt. - Shelter Cove - Ward Cove will be in the vicinity of a petroglyph reported in Shelter Cove and a large historic site identified by Sealaska Corporation in Leask Cove.. The potential for archeological sites along the inland portions of the transmission line is low. c. Mahoney Lake: There is a petroglyph reported in the vicinity of the cove east of Mahoney Lake, and anabandoned mine near the creek mouth. Potential in this area may be considered high. The first half of the transmission route to Beaver has a. medium to low potential; the second half has a low potential. Dr. Robert Ackerman, Department of Anthropology, Washington State University, Pullman, Washington, has conducted a partial archeological survey of the Swan Lake Hydroelectric Project for R. W. Beck and Associates. When this survey is completed, we will be in a position to provide firmer data concerning historic/archeological materials for that portion of the study area. 6200-11 (1/69) EIS-A-11 O94. 5 237. STATE OF ALAS | mm DEPARTMENT OF NATURAL RESOURCES nluwieretesten er. eas bso February 2, 1979 - i” DIVISION OF PARKS Anchorage, Alaska 99501 Re: 1130-2-1 J. K. Soper, Chief Engineering Division : Alaska District, Corps of Engineers P.O. Box 7002 . . Anchorage, Alaska ~99510 Dear Mr. Soper: This letter is in response to your request of January 29th for our views on the Mahoney Lakes and Lake Grace projects and their involvement with archaeological or historic properties (your reference NPAEN-PL-EN). Our comments generally parallel those of Dr. Gerald Clark. in his letter to your office which you had enclosed. We feel that the Mahoney Lakes area of the camp and access road and the saltwater access area should be archaeologically surveyed prior to any finalization of plans. The power line as Dr. Clark noted appears to be a low potential area; however, we would like to see the documentation of the possible or probable impacts on the mines indicated in your routing sheet.- In the Lake Grace area the power line as Dr. Clark again mentioned is a low probability area; however, the access area and camp area near salt water is very high in potential and we again concur by feeling that an archaeological survey should be done in that area. If you have any further questions, please contact us. Sincerely, lary Merah William S. Hanable State Historic Preservation Officer DR:pg cc: Dr. Gerald Clark, Regional Archaeologist U.S.D.A. Forest. Service P.O. Box 1628 Juneau, Alaska 99802 EIS-A-4 DEPARTMENT OF NATURAL RESOURCES 10-JT1LH / / ee JAYS. HAMMOND, GOVERNOR STATE OF ALASKA - . 619 WAREHOUSE DR., SUITE 216 ANCHORAGE, ALASKA 99501 __ DIVISION OF PARKS — PHONE: 274-4576 April 27, 1982 File #: 1130-2-1_ Harlan E. Moore. : Chief, Engineering Division © Corps of Engineers, Alaska District P.O. Box 7002 — Anchorage, AK 99510 Dear Mr. Moore: We have reviewed the "Cultural Resources Assessment for Mahoney Lakes Hydropower Project" (Re: NPAEN-PL-EN) prepared by Julie Steele of your office. In light of Ms. Steele's survey results we concur with the finding of no probable impact to significant cultural. resources by presently proposed construction. However, should cultural resources be located during the course of construction, we request that the project engineer halt all work which may disturb such, resources and contact our office immediately. As always, thank you for your concern for Alaska's cultural resources. Sincere] iW pl ane Historic Preservation Offi \= ra Seat 5 : WALTER J. HICKEL, GOVERNOR OFFICE OF THE GOVERNOR OFFICE OF MANAGEMENT AND BUDGET DIVISION OF ee. COORDINATION (9 a SOUTHCENTRAL REGIONAL OFFICE CENTRAL OFFICE oO PIPELINE COORDINATOR'S OFFICE “3601 °C" STREET, SUITE 370 P.O. BOX 110030 411 WEST 4TH AVENUE, SUITE 2C ANCHORAGE, ALASKA 99503-5930 JUNEAU, ALASKA 99811-0300 ANCHORAGE, ALASKA 99501-2343 PH: (907) 561-6131/FAX: (907) 561-6134 PH: (907) 465-3562/FAX: (907) 465-3075 PH: (907) 278-8594/FAX: (907) 272-0690 01-A35LH June 21, 1994 sla Wices ae FOX Mr. Micheal V. Stimac e ne Lae HDR Engineering, Inc. Suite 1200 DaAl{ty 500 108th Ave., NE Hywe- Bellevue, WA 98004-5538 % and filo, BY. & Mahondgc, Mr. Douglas Campbell g- Cape Fox Corp. P.O. Box 8558 Ketchikan, AK 99901 Dear Mr. Stimac and Mr. Campbell: SUBJECT: MAHONEY LAKE HYDROELECTRIC PROJECT STATE ID #AK9403-33JJ/FERC PROJECT #11393 . FIRST CONSULTATION PHASE The Division of Governmental Coordination (DGC) has completed coordinating the State’s informational review of the City of Saxman’s proposal to construct a small (9.6 megawatt) hydropower plant near Mahoney Lake, about 5 miles northeast of Ketchikan. The Mahoney Lake project is described in detail in the following documents and will not be re-described here: (1) Mahoney Lake Hydroelectric Project Initial Consultation Document, March 1994 by HDR, (2) Joint Agency/Native American/Public Meetings packet, not dated (received on 5/19/94 by the DGC), by HDR. The purpose of the project is to provide the Ketchikan area with an additional energy supply. We are at the Preliminary Permit/First Consultation Phase of the FERC review. As the process for obtaining a FERC license requires extensive preapplication consultation, this review is informational, for the purpose of the agencies providing resource information about the project area to assist in completion of the FERC application. Identification of permits will occur in the Second Consultation Phase. The State’s coastal consistency review will be commenced when all permit applications are submitted and FERC officially accepts the application and issues a public notice (Third Phase of the FERC review). 8 © © @ O At this point in the FERC review, the City of Saxman/Cape Fox Corp. will prepare the following study plans: (1) water quality and quantity, (2) fisheries/aquatic resources, (3) wildlife/botanical resources, (4) historic/archaeological resources, (5) recreational resources, (6) aesthetic resources, (7) land use, and (8) erosion and sediment control. Comments received by this office are briefly summarized in this letter. The state agency comments are enclosed for your use in preparing the FERC application and contain more detailed information about the State’s concerns and interests. The Department of Environmental Conservation (DEC) was unable to examine this project in detail due to staff shortages. However, the DEC advises that an NPDES (i.e. Storm Water Discharge) permit from the Environmental Protection Agency may be needed. In addition, a Certificate of Reasonable Assurance under Section 401 of the Clean Water Act may be required as the state authorization of various federal permits needed for the project. The Department of Fish and Game (DFG) advises that additional information regarding potential impacts on stream flows and temperatures is critical. In particular, the DFG is interested in the relationship between upwelling and sockeye salmon spawning along the western shore of Mahoney Lake. More frequent monitoring of salmon spawning is also suggested by the DFG to avoid missing the peak spawning period, resulting in incomplete data. The DFG has also requested identification of streams used by fish and that more information on wildlife/botanical resources be provided. The Department of Natural Resources (DNR) - Division of Water & Mining (DWM) advises that a water use permit has been received and serialized as LAS #14359. DWM concurs with the DFG’s request for additional information about the potential effects of the project on stream flows and temperatures and the relationship of the flow regime to fisheries. DWM also requests that the proportionate contribution of upper Mahoney Creek to the Lower Mahoney Lake inflow be calculated and that the effects of any reduced inflows to Lower Mahoney Lake be graphed as a post-project hydrograph. The Division of Land has not commented on the project. The Division of Parks and Recreation, including the State Historic Preservation Office, commented directly to HDR and did not submit copies to this office. The Ketchikan coastal district submitted comments directly to HDR and to this office. The district advises that the local coastal management plan is currently being revised and new policies may be adopted during the life of the Mahoney Lake project. The current draft revision offers support for the project. The district also states that the project is consistent with the local zoning ordinance and comprehensive plans. Construction activities will require a local zoning permit. 16:15 No.00S P.02 CLERK/PLANNTNG OFFICES TEL:907-247-84349 Jun 01,94 KETCHIKAN GATEW..Y BOROUGH ( art of Planaing and Community Development . ee Froal Sirect + Ketchikan, Alaska youl Gury Munsterman, Director . Z ole | ' 907) 228-6610 -May-26, 1994-° . Blas telah | Ne al i hee ee em eS eed 907) 247-2499, Michael V. Stimac. HDR: Engineering, tne: ; Trad 500 108th Avenue, NE, Sulke 1200 Bellevue, WA 98004- 5538 SUBJECT: Mahoney Lake Hydroélectric Project I am in receipt of your recent transmittal regarding the consultation meetings in Ketchikan on April 26. I was unable to . attend the entire briefing and apparently arrived at. the. nae ok 2 Lodge: session ‘as. ‘the | cIReeting. was. cotiplet ‘ “Phe Department Has. “no. specific ‘comments, “at this time. The” wag Bs Department is engaged in the process ¢f updating. the Coastal Zone’ Management Plan which inclu ides a required energy faci lities element. The current draft eee the subject proposal and suggasts that the AOneRALEY support it as a part of an objective i which seeks to meet the demand for “affordable electric power. While proposed policies have not been subject to public review, I would anticipate that policies will be adopted during the course of the project study timeline. I would be pleased to share the a draft recommended plan with you or your associates when it becomes available later this summer. Please do not hesitate to contact me if you have any questions. Sincerely ea ey {Eu ary Munsterman, AICP Planuina Director c: Doug Campbell, Cape fox Corporation Veronica Slajer, City of Saxman PR plat satizal-iez CLERK/PLANNING OFFICES TEL:907-247-8439 ( KETCHIKAN. GATEWAY BOROUGH Department of. oe and Community Lt aeuik = 344 Front Street .¢ Ketchikan, Alaska 99901 4 “Gary Muosterman Director Jun 01,94 16:14 No.005 P.01 MPA re | LSA, (907) 228-6610 ot ‘Fax: (907) 247-8439 Christine. Walentiné eae Project: Review Coordinator ee Ws Division of: Governmental Coordination | “P.O... Box 110030 © Juneau, AK 99811 Re: — Mahoney Lake Hydroelectric Project ~ Initial ‘Consultation .- CZMP Consistency Review State ID: AkK9403-3300 - Project: Deseription ~ ee eee Wes ee ae See - gris pr: ject” consists: “of the initial eonsiltation ‘gtage » ‘fo : eo upcoming” hydrcelectric - project at Mahoney Lake. This propdésed. - : project site is located approximately five (5} miles northeast of the City of Ketchikan. This project is located within the Future Development (FD) Zone and is a permitted uee within that zone. The applicant ia the City of Saxman. Findings The Ketchikan District has reviewed the above referenced application. At this time the District has no specific comments to make about this preject. Enclosed with this letter is a copy of the letter that was transmitted to HDR Engineering from Gary “Munsterman, Planning Director for the Ketchikan Gateway Borough. THis letter is in response to the scoping meeting that was held in Ketchikan on April 26, 1994. This project is also consistent with and supported by the Ketchikan Gateway Borough Zoning Ordinance and Comprehensive Plan. Zoning Permit Lf construction is anticipated for this project a zoning permit will be required from the Borough. Sincere Ve Lip be Till Stephen G. Ranis Zoning Administrator I\S\CZM\1994\9403337.7.MAH 1 If you have any questions regarding this letter or the Alaska Coastal Management Program,. please contact me at 465-3177. Sincerely coe LK, Christine Valentine Project Review Coordinator Joan Hughes, DEC, Juneau Lana Shea, DFG, Juneau Jack Gustafson, DFG, Ketchikan Elizaveta Shadura, DNR/DOL, Juneau Jim Anderson, DNR/DOL, Juneau John Dunker, DNR/DOW, Juneau Gary Munsterman, Coastal Contact, Ketchikan Encle serge KK KK KK KK KK KKK KK KKK KEK KK KKK KKK EK KKK KKK KK KKK KKK KKK KEK KEK KEKEKKKEKKKKKKKKKKKKKKKKKEKEK *** REQUESTOR: GCHCCEV - Valentine, Christine 01DGC (kee HH KKK KKK EK KEE KER EER EKER KEE KEKE KEKE EE EK EEE EKER EE RHEE KEEEEREK KKK eee th) | eel ela] | SYSM:.INBASKET PRINT We | EL | | dap MESSAGE . a 650817 A TIL DATE:. 96/20/94 | TIME: 16:32 PRIORITY: 000. “ecaccey. ~ Valentine, : ‘Christine TO: - Project. ‘Review Coordinator’ aot -01DGC - > : “e. ‘Oe oy 110030- Tate FROM: -: |. NWRCJDU - Dunker, John Water Resource Officer 1LODWR 400 Willoughby Ave., 4th Fl. Junéau, AK 99801 2. 130 ee ‘SUBJECT: * “Mahoney Lake hydro Christine: I have the following comment on th Mahoney Lake initial consultation phase: - We support the suggestions made by ADF&G in the memo from LanaShea to you of 3 June, paragraph 3. - We suggest that the proportionate contribution of upper Mahoney Cr. to total Lower Mahoney Lake inflow be calculated. - We suggest that the effect of reduced intake flows into Lower Mahoney Lake from accumulating storage in Upper Mahoney Lake be graphed as a post-project or operations phase hydrograph. John Dunker, DNR/Water & Mining/SE Sent to: GCHCCEV - Christine Valentine (to) > MEMORANDUM OFFICE OF STATE OF ALASKA To: | did .a good job in describing the ‘scope: and intent..of., the: project . dats el «elise “This will. form*the basis for: ‘completing this* ‘project « in-an- i eee Gal vexpeditious manner. * : ‘ . ’ MANAGEMENT & BHOGEITMENT OF FISH AND GAME JUN 8 1994 | Christine Valentine ATE > June 3, 1994 Project Coordinator Division: of GovernneG@OVERNMENTAle: “AK9403- 3390, ; Coordination - _,COGRDINATION : _. Juneau. r sig . ° . PHONE? 225 - 2027. ‘Daria’ Shea ic " gusgecr: ~ Mahoney ‘Lake Hydroelectric.: °:- Regional Supervisor : Project, FERC Project ~ Habitat & Restoration : No. 11393 Douglas . We have the following comments regarding the initial consultation phase for the Mahoney Lake Hydroelectric project. The Initial Consultation Document (ICD) and associated meetings Of particular concern will be acquiring additional information concerning changes in stream flows and water temperatures as a result of the project. This includes learning more about the stability of the flow regime which supplies the upwelling utilized by sockeye salmon spawning along the western shoreline of the lake. It will be important that the temperature and flow modeling and analysis be combined with the results of the fish studies ina Manner that accurately predicts the effects that the project might have on fish productivity. We would also suggest more frequent monitoring of the Mahoney Lakes sockeye spawning cycle to more accurately determine the “timing and abundance of this run. Otherwise, the site visit planned for September could potentially miss the peak spawning period and result in inadequate data regarding the location of spawning and overall site productivity. Also, there may be uncataloged anadromous and/or resident fish tributaries in the vicinity which, if present, should be identified. The wildlife and botanical objectives during the review phase for this project, however, are more vague. One concern not mentioned, for example, might be the transmission line which goes from Mahoney Lake to the Swan Lake corridor. The next phase of the project should describe the mitigative measures proposed to minimize potential collisions with large birds (such as swans and geese utilizing Mahoney Lake) or the electrocution of raptors. Additionally, we do not have a copy of the 1983 Corps of Engineers DEIS referred to in the ICD. We would like to receive a copy of this for our files regarding this project. Thank you for the opportunity to comment. cos Jack Gustafson, ADF&G, Ktn Elena Witkin, ADEC, Jnu Bruce Johnson, ADNR, Jnu Houston Hannafious, COE, Anc @ Michael Stimac 2 I would like to encourage you to continue consulting with the Federal Energy Regulatory Commission. Thank you for the opportunity to review and comment on the initial consultation document. If you have any questions, please contact Teresa Trulock at this office. Sincerely, Lene. STEVEN T. SEGOVIA District Ranger Enclosure ce: RO Lands SO Lands Hector Perez, FERC {as FS-6200-28(7-82) . COMUDAL, (Cape Cee Slayer, Sax wr Ry CIR ° a Src, Ka United States Department of the Interior AO AG are ‘S ey FISH AND WILDLIFE SERVICE Al, 64. 2-A chow Southeast Alaska Ecological Services 3000 Vintage Blvd., Suite 201 Juneau, Alaska 99801-7100 RECEIVED IN ANCHORAGE IN REPLY REFER TO: JUN 2.4 1994 | HDR ENGINEERING, INC. June 21, 1994 Anne Leggett HDR Engineering, Inc. 2525 C Street Suite 305 Anchorage, AK 99503-2689 . elk oe Dear Ms. Leggett: This responds to your June 3, 1994 letter requesting information about threatened, endangered or candidate species that may occur in the vicinity of the proposed Mahoney Lake Hydroelectric Project on Revillagigedo Island near Ketchikan, Alaska. For the purposes of the Endangered Species Act (ESA) Section 7 consultation, we offer the following comments: Based on available information, the following threatened or endangered species may occur in the proposed project area. Common Name Scientific Name ESA Status American peregrine falcon Falco peregrinus anatum endangered arctic peregrine falcon Falco peregrinus tundris threatened @ Both of these peregrine falcon subspecies may occur in the project area as transients, primarily during seasonal migration. No critical habitat has been designated for these species. On December 13, 1993 the Fish and Wildlife Service (Service) received a petition to list the Alexander Archipelago wolf (Canis lupus ligoni) as threatened pursuant to the Endangered Species Act. On May 20, 1994, the Service published a notice (Federal Register Vol. 59, No. 97, pp. 26476-26477) @ of a positive petition. finding which initiated a status review of the animal. This notice of positive finding in effect confers Category 2 candidate status to the Alexander Archipelago wolf. The final decision on whether or not to list this species is anticipated during December of this year. Wolves are present on Revillagigedo Island and likely exist in the project area. We suggest that it may be prudent to include the wolf in your environmental review given the uncertainties about its status at this time. The following comments regarding Category 2 candidate species are offered as technical assistance for your consideration. Category 2 species are those for which there is information indicating the species may qualify for endangered or threatened status, but further evaluation is needed. Three Category 2 APPENDIX D TEMPERATURE INFORMATION United States Department of the Interior FISH AND WILDLIFE SERVICE P. O. Box 1287 Juneau; Alaska 99802 IN REPLY REFER TO: December 21, 1981 Colonel Lee R. Nunn District Engineer Alaska District, Corps of Engineers P. 0. Box 7002 j Anchorage, Alaska. 99510 Re: . NPAEN-PR-R Attention: Environmental Section Dear Colonel. Nunn: This planning aid letter is to re-evaluate some of our recommendations and to transmit new information relative to the Mahoney Lakes hydropower project near Ketchikan. We have been involved with this project to some . degree since 1977 and produced planning aid reports and finally a Coordination Act report containing some recommendations which were ultimately challenged. In the early stages of the project we judged the most significant adverse effect to be expected from the project would be the loss of the stream between Upper Mahoney Lake (storage reservoir) and Lower Mahoney Lake. The suitable. spawning gravel contained in this stream comprised about one-half of the total spawning gravel in both tributaries to Lower Mahoney Lake. Since the Mahoney Lakes system supports a run of sockeye salmon, we keyed in on this potential loss as the most significant adverse effect expected from the project. Ultimately in the CA report we recommended serious consideration of measures, including an artificial spawning channel, to mitigate this expected loss. These early evaluations assumed use of the.stream in question by adult sockeye salmon since adults were observed in the stream leading to Lower Mahoney Lake from saltwater. The assumptions were based on accepted life cycle knowledge for the species. Observations made this past fall significantly modify these early assumptions and will be reported later in this letter. Also challenged in the CA report were problems relating to use of the Habitat Evaluation Procedures (HEP) format. During the drafting of the CA report, the decision was made to use the HEP format which was just being developed. Unfortunately, misconceptions of the use of HEP prevailed: among the authors. Also, the data base, which had not been collected with. HEP in mind, was used without the benefit of the appropriate sample design. The overall result was a rightfully criticized presentation of the procedure. EIS-B-11 2. At the outset, HEP was considered to be. a highly involved standardized procedure in which the major product would be the identification of a : quantity of other lands necessary for mitigation. As HEP evolved it became clear that HEP can be used to accomplish any one or more of the following: : 1. Quantify lands necessary for mitigation (as before) 2. Evaluate alternatives . -"3. Predict recovery Also, it has become evident that the procedure can ones from an expensive large scale elaborate procedure (when the project merits it) to a rather informal minimum expense project for a specialized purpose; and, there are many projects which are not suitable for the application of HEP. ote” ys The suitability of the Mahoney Lakes project for the application of HEP is questionable and it may not have been initiated under our present state of knowledge. However, we do see some value in the salvage of these efforts. Testing models and streamlining the HEP process for southeast Alaska could be an important part of this project. The southeast Alaska ecosystem is relatively homogenous and information acquired here could be applied on . more suitable projects. In the normal life cycle for sockeye salmon the adults swim upstream into a watershed system containing a lake. The adults then usually spawn in the gravels of tributary streams to the lake. Occasionally, when forced to, the adults are known to spawn in the gravels downstream from the lake and/or along the lakeshore in the gravels of the alluvial deltas formed by the tributaries. The young fry, after hatching, migrate to the lake and rear a year or more before migrating to sea. When the young fish hatch downstream from the lake they must be able to navigate upstream to reach the lake. This is likely not possible in the Mahoney Lakes system. Between July 16 and November 1, 1981, ten stream censuses were conducted. Adult sockeye salmon were again observed to be present in the stream from tidewater to the lower lake but not in either tributary stream to the lake. Also, the stream between Upper Mahoney Lake and Lower Mahoney Lake was observed to exhibit extreme variance in surface flow both from date to date and from the base of the falls to the lake. Also, the rocks, gravel and other characteristics of the stream exhibited evidence of violent flow patterns. These observations and the lack of observed sna:ming upstream from the lake serve to strongly suggest that the adult sockeye are not spawnins upstream from the lake. Since it is extremely improbable that the younz fish can nisrate upstream to‘ the lake, we strongly suspect that the adult fish are spawning in the lake along the face of the tributary deltas at unobservable depths. If the above is correct then the primary concern would be to insure that . the tailrace waters re-enter the stream sufficiently to percolate through the gravels of the delta. As we view it, that stipulation should be easy EIS-B-12 3. to meet. We will be submitting a modified CA report with re-evaluated recommendations. : ae : . Additional information requested by. your engineering section follow: Water temperature profile in Upper Mahoney Lake on August 3, 1977 Depth Temp. Depth ‘Temp. Depth Temp. Depth ._Temp. Surface 9.0 8 6.0 >» . 16 4.8 32 4.2 1°. BS 9 5.8 WV 4.8 . 40 4.1 2 77 10 5.6 46 50 4.0 3 7.4 11 5.4 19 4.5 4 71.2 12 532 20 4.5 5 6.6 13 5.0 21 4.5 6 6.4 14 4.9 30 4.2 7 6.2 15 4.9 31" 4.2 Depth measured in meters; temperature in degrees centigrade. Water temperature on surface of upper lake near outlet Date Temperature °C April 24, 1978 0.2 May 8, 1978 0.5 March 21, 1979 0.1 July 25, 1979 10.0 February 16, 1981 0 May 17, 1981 0 August 29, 1981 ar5 Water temperature in lower lake on the face of the delta (the area suspected to be used for spawning). December 9, 1981 3E5oC EIS-B-13 4. On December 9, 1981, a recording thermograph was installed on the face .of _ the delta in approximately 15 feet of water and.will be recovered five months later. The resultant information should help define the. temperature regime in this area. , 2 ; ‘Incubation time varies with water temperature from around 140 days at about 4°C to around 50 days at ‘about 15°C for sockeye eggs. The ecological implication of a modified incubation time (an expected result of a change in water temperature) is fry being released into the lake at a different stage of seasonal lake plankton development. The overall impact to the fishery resource could vary from positive to negative depending on a multitude of factors including the degree of change. We feel it is beyond. the scope of our resources to study this sufficiently to predict it and that the relative rotential' impact on the fishery resource in this rroject doés not warrant it. We hope the information in this letter proves useful. Sincerely yours, Mer & Ber . Field Supervisor EIS-B-14 APPENDIX E GEOTECHNICAL INFORMATION Shannon & Wilson Geotechnical Information EF REIT ORE FER TN IT ee oprapepearenty: W-6527-01 Mahoney Lake Hydropower Project Trip Report and Geotechnical Pre-Feasibility of the Proposed Tunnel Alignment July 1993 HDR Engineering, Inc. 500 - 108th Avenue N.E., Suite 1200 Bellevue, Washington 98004-5538 SHANNON & WILSON, INC. GEOTECHNICAL AND ENVIRONMENTAL CONSULTANTS 400 N. 34th St. = Suite 100 P.O. Box 300303 Seattle, Washington 98103 206 * 632 = 8020 SHANNON &WILSON. INC. TABLE OF CONTENTS Page 1.0 MAHONEY LAKE TRIP REPORT ........... 2. cece eee eee neces 1 MELD General Wevereiciele sore ele ore itcio cic oirouronicretro) obciieliclicl-e evfel elievielrel oiienteliaterte 1 152 GOOIORYAenerener bel ether oiekode Renee l-icieicieroreicl cient elohn och or erste nsioie 1 1.3 Intake/Diversion Site... 1... 1. etc ce cc ccc ce tec e eee eees 2 174 Penstocks 55 2 55 3 te orl at © forsie © el oS teicrie) ole) ote elie) oie oe (el of ote) 21 3 TS) POWernOUSe 5) oorie oe) o) eo) oro) fol e) @ cle ©) ie 6) o) isle) os lel) els) ice 4 16 Access Roads 2) <)iey aster a coyote) ile fo) atrolistiay ce (oat eletie se) ohiclleli effete! a) ot e)iotle)/=) e)ret = 4 2.0 GEOTECHNICAL PRE-FEASIBILITY OF PROPOSED TUNNEL ALIGNMENT 5 Del BSCOPE Of WOTK 5) eel itelredoieior elielen a) ito lelre) one nciio ol eiteyie ieee elie elieitelieviel oie re 5 2.2 Description of the Proposed Layout ........... 02.2 e eee eee eee 5 220 lypintake!ShattyAreatsars creel ele )o) elkelee tele) seth erelier el onelisirelsedener 5 22.2) Outlet, Portal Area yar neneNon ane honor lence reitel oaenene! orlen loli enon Nelle 6 223 Mm LUNMEL opel oi ieelioneicd sl cien on elronsicie loys) oleic siicliel elon rel neonate 6 2.3 Excavation, Initial Support, and Final Lining ...................4. 6 2.3.1 Excavation and Support at the Outlet Portal ................ 7 2.3.2 Tunnel Excavation and Initial Support .................... 7 PR i) Sil SeenaceemathorurPclons GIOIO OD Ol O lO ODO oloo Ginko a ole 8 2.3.4 Intake Shaft Excavation and Support.................000- 8 2-4 Design Level Explorations yo...) oye) siecle clo) clone eerie one eileen el ees 9 a 2.4.1 Geotechnical Mapping and Trenching .................--4. 9 2.4:2. ‘Bosings and Seismic Surveys) ~ < -). 15 seis 1505 0 56 « 9 TABLE Table No. 1 Estimated Construction Quantities and Costs i W-6527-01 SHANNON &WILSON. INC. TABLE OF CONTENTS (cont.) IST OF Figure No. 1 Site Plan 2 Tunnel Profile APPENDIX IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING REPORT ii W-6527-01 SHANNON &WILSON. INC. MAHONEY LAKE HYDROPOWER PROJECT TRIP REPORT AND GEOTECHNICAL PRE-FEASIBILITY OF THE PROPOSED TUNNEL ALIGNMENT 1.0 MAHONEY LAKE TRIP REPORT 1.1 General The purpose of this trip report is to describe observations, conclusions and preliminary recom- mendations regarding the geotechnical aspects of a proposed hydroelectric facility at Mahoney Lake, located approximately 7 miles northeast of Ketchikan, Alaska. The project involves the diversion of water at or near the outlet of Upper Mahoney Lake in the vicinity of elevation 1850 feet, and conveyance to a powerhouse along Mahoney Creek, upstream from its entry into Mahoney Lake, as shown on Figure 1. The elevation of Mahoney Lake is 130 feet and the elevation of the proposed powerhouse site is 160 feet. Prior to this site visit, Mr. Jack Snyder of HDR used U.S. Geological Survey (1:63,369) and U.S. Army Corps of Engineers (COE) (1:4,800) topographic maps to prepare a preliminary project layout. He was aided by previous studies that had been performed by R.W. Beck of Seattle and the COE. The purpose of this site visit was evaluate the feasibility of a hydroelectric project at the site, based on field observations. Shannon & Wilson’s scope of work included the review of reports and letters by R.W. Beck and the COE that were obtained by HDR; review of published geologic literature; and a site visit on June 21 and 22, 1993. Accompanying Bill Laprade of Shannon & Wilson on June 21 were Jack Snyder and Don Thompson of HDR; Doug Campbell, Eric Mench and Bud Johnson of Cape Fox Corporation; and Jan Risla of Ketchikan Public Utilities. On June 22, Shannon & Wilson and HDR personnel visited the site alone. There is no road access to the site. Access was gained by helicopter, provided by Temsco of Ketchikan. 1.2 Geology Geologic conditions in the project area are dominated by bedrock formations. The most widespread rock in the area is a schist or phyllite. Where this Paleozoic to Mesozoic formation has not been affected by igneous intrusions, it is relatively weak and much slope instability is common. However, heat from a large Tertiary intrusion of gabbro baked these rocks in an aureole around the perimeter of the intrusion. The heat transformed the schist/phyllite to a much harder, more competent rock. The unconfined strength of the rock increased by perhaps as much as 2 to 10 times. The very large gabbro intrusion is closest to the project area just west of the west end of Upper Mahoney Lake, and it extends westward to the city of Ketchikan. Within the project area are smaller intrusions of quartz diorite, based on reports by others and the 1 W-6527-01 SHANNON & WILSON. INC. observation of quartz diorite cobbles in the creek. The number, size and location of these small intrusions are unknown. The area is known to have been glaciated; however, no glacial deposits were observed during this site visit. Holocene deposits are colluvium, alluvium and muskeg. Colluvium included talus, avalanche deposits and landslide deposits. Alluvium included active stream deposits and alluvial fans. Muskeg is fragmented remains of decayed vegetable matter accumulating in bogs; it can range from nearly all vegetation (peat) to organic silt with peat (muck). The site is crossed by faults and lineaments that are probably indicative of minor shear zones in the bedrock. Two of the faults recognized by the COE may cross the alignment of the penstock/tunnel. Other parallel lineaments are also shown on the Site Plan, Figure 1. Many of the avalanche chutes in the area are in the lineaments, some of which are not recognizable on the topographic maps. It should be noted that the topographic maps by the U.S. Geological Survey and the COE are not detailed enough to represent the actual topography of the site. In my opinion, the ground is much more rugged and broken than indicated on these published maps. Slope instability in this area is primarily rock fall and small to moderate size rock slides. These incidents appear to occur even where bedding is apparently favorable, the instability being the Tesult of bedrock joints. Because of the hard and blocky nature of the schist/phyllite, the rock blocks are generally rectangular. Where recent debris avalanche deposits were observed, large woody debris comprised a large portion of the deposit. 1.3 Intake/Diversion Site Diversion sites were evaluated over a distance of about 2,300 feet starting at the outlet (north end) of Upper Mahoney Lake. The sites were (1) at the mouth of the outlet, (2) about 450 feet downstream of the outlet, and (3) about 2,300 feet downstream of the outlet. In general, the bedrock at the sites dipped steeply (36 to 58 degrees) to the west and bedrock was exposed on the right bank at each of the three sites. The left side of the valley was heavily laden with talus that was shed from high cliffs to the west. The site at the mouth and the site farthest down- stream appear to have significant volumes of talus on their left abutments; however, the site about 450 feet downstream from the mouth contained bedrock on the left abutment. Access to the site about 450 feet downstream from the mouth would require minimal amount of rock excavation for road and penstock access compared to the site at the mouth of the outlet. While access to the site 2,300 feet downstream would be favorable, a higher dam would be needed for an entrance to a drop shaft or penstock and a subsidiary dike would be required across a low saddle to the east. In my opinion, the site that is 450 feet downstream of the mouth of the lake (see Figure 1) is preferred from a geotechnical standpoint. 2) W-6527-01 SHANNON &WILSON, INC. One hazard that cannot be mitigated at any of the diversion sites is rockfall. The bedrock cliff to the west of the creek did not appear to be affected by large scale or deep-seated rock slides; however, there appeared to be continual rock falls and small rock slides. Such rockfall or slides could damage the diversion dam and the intake structure. Rock deflection berms have been constructed in alpine areas; however, such a structure would not be effective against a large volume of rock debris. We understand that a rock fill dam with a concrete facing, similar to that at the nearby Beaver Falls Hydroelectric Project, is anticipated. We concur that the ubiquitous schist/phyllite rock blocks would be suitable for such a structure. The hard schist/phyllite bedrock on both abut- ments would be suitable for embedment of the concrete cutoff and wing walls. Because of a bedrock swale that is present to the west of the west bedrock abutment, it may be necessary to fill in that area to create a buttressing effect for that abutment. 1.4 Penstock There are two distinct topographic sections on which the penstock would be located. The upper portion is relatively flat gradient from the preferred intake site to about 1,500 feet downstream. Because the wide bowl just downstream of the intake site is subject to flooding, channel migration, loose alluvial soils and avalanche deposits, it will be necessary to keep the penstock on the higher ground to the south and east of the bowl. This route would be in bedrock (schist/phyllite). Where the penstock crosses two avalanche chutes, the pipe would have to be encased in concrete and buried in rock. - The second portion of the penstock is the very steep slope that has an average inclination of 45 degrees between about elevations 1,900 and 400 feet. There is a gently sloping bowl between elevations 400 and 300 feet, where a major tributary (avalanche chute) crosses the proposed alignment. The ground surface then steepens to about 30 degrees on the hillside just above the proposed powerhouse site. Based on the contours on the two published maps, the construction of a penstock would have been feasible; however, as discussed above, the actual ground topography bears little resemblance to the contour maps. In reality, the ground is a series of cliffs and swales. The cliffs are vertical to overhanging and 50 to 200 feet high; the swales are incisions that appear to be avalanche chutes. In the large bowl area between elevations 400 and 300 feet, much of the bowl appeared to be filled with slide or avalanche debris. The only route around this bowl would require a southward tur of the penstock that would require sidehill construction. In my opinion, this is inhospitable terrain for the laying of a surface penstock. It was agreed among all interested participants that a tunnel was the only viable means for water conveyance. In order to match the preferred intake site, a gradient would be required that is too steep for tunnel mucking equipment. Therefore, a combination of tunnel and raise-bore was considered. Gerry Millar of Shannon & Wilson is preparing a pre-feasibility report for the 3 W-6527-01 SHANNON &WILSON. INC. geotechnical aspects of the tunnel. A relatively level saddle in the topography about 1,500 feet downstream of the intake site would require minimal site grading to create a level working area for the raise bore and the installation of the vertical penstock section. 1.5 Powerhouse From the inlet of Mahoney Creek to Mahoney Lake, our field party walked approximately 1,200 feet upstream across an alluvial fan, at which point the creek became incised in a bedrock channel, as indicated on Figure 1. Hard schist/phyllite, similar to that at the right abutment of the intake/diversion site, outcropped on both side of the creek and in the channel bed. The dip of the bedding was at approximately right angles to that at the intake/diversion site; that is 60 to 80 degrees to the north. As discussed in the COE report, this divergence of bedding dip requires a fault in between the two sites. In my opinion, this site is suitable for construction of a powerhouse. It should be built into the bedrock hillside. The excavation would have to be blasted and the south side, in particular, would require temporary support by rock bolts to prevent bedding plane rock slides during construction. The ridge of rock in which the power- house would be situated would be out of the path of the avalanches that appeared to have endangered the powerhouse site as shown on the COE project. 1.6 Access Roads We understand that road access will not be attempted to the intake/diversion site. By inspection of topography and the geologic conditions, such a road would be cost-prohibitive for the proposed hydropower project. We understand that a new road would be required from the White River delta to the proposed powerhouse site, a distance of about 5 miles. Reconnaissance of this alignment was limited to observations from the helicopter, except for the 1,200 feet from the west end of Mahoney Lake to the powerhouse site. Between the White River delta and the outlet of Mahoney Lake the road would traverse gently to moderately sloping terrain; nog signs of slope instability were observed from the helicopter. The ridge containing Mahoney Lake on the east side appeared to be composed of bedrock . Along the south side of Mahoney Lake, a delta has been built into the lake and two distributaries run across the fan. In between the creeks, muskeg was widespread. In the area between the inlet to Mahoney Lake and the powerhouse site, there was abundant evidence of an actively migrating channel and periodic inundation. A road located in this area would have to be constructed on an embankment to reduce the chances of destruction during an avulsion or from an avalanche. Nevertheless, periodic maintenance and reconstruction may be required during the life of the project. 4 W-6527-01 SHANNON &WILSON. INC. 2.1 Scope of Work The present scope of work consists of the evaluation of preliminary engineering geology and geotechnical information at the intake shaft, outlet portal, and along the tunnel and shaft align- ment. Included in this information are the preliminary selection of shaft location, support and lining types and excavation procedures for the tunnel and shaft, and the preparation of prelimi- nary engineering estimates of quantities and costs for the tunnel and shaft construction. Preliminary engineering geology information is presented in section 1.2 of this report and in Appendix B of the Corps of Engineers report dated 1978. The principal objectives of the investigation are to establish the foundation conditions and the nature of the ground along the tunnel route and shaft, and identify any major geotechnical problems that could adversely affect project costs or schedules. Furthermore, the report makes detailed recommendations on the type and location of subsurface explorations (borings, seismic surveys, etc.) required for further project design. No borings were contemplated during the present study because of the cost of access to the principal sites. Once the overall feasibility of the project is established, the considerable cost of access and subsurface exploration can be justified. 2.2 Description of the Proposed Layout The objectives of the proposed layout are to deliver water under a head of approximately 1,700 feet and to produce electricity at a new powerhouse near Mahoney Lake. The intake area will Tequire an approximately 10- to 15-foot-high dam just north of Upper Mahoney Lake and an intake structure 1,800 feet downstream of the dam on the right bank of the river, as shown on Figure 1. The water will drop down a 32-inch-diameter pipe placed in a 48-inch-diameter shaft from elevation 1,850 to elevation 200 feet, and then along a pipe placed in an 8-foot-wide by 8-foot-high horseshoe-shaped tunnel to elevation 160 feet. The tunnel is aligned approximately east-west, and will be 2,700 feet long. Cover over the tunnel varies from 10 feet at the outlet portal to 1,650 feet at the junction with the drop shaft. 2.2.1 Intake Shaft Area The intake portal (elevation 1,850 feet) will be located on the right side of Upper Mahoney Creek approximately 1,800 feet downstream of the damsite. Bedrock is slightly weathered, schistose to slabby greenstone (phyllite to schist) that will require minimal preparation as part of the intake shaft construction. Only limited construction will be performed at this site, likely only the concrete pad for drilling of the pilot hole for the raise bore since the rest of the tunnel and shaft will be excavated from the outlet portal. Access to the area is difficult and construction 5 W-6527-01 SHANNON & WILSON. INC. activity will have to be supported by helicopter. The intake shaft will be 4 feet in diameter and constructed in one pass with a Robbins or Atlas COPCO type raise borer. 2.2.2 Qutlet Portal Area The outlet portal will be located at elevation 160 feet on a shallow slope (1.5/1 to 1/1). The'portal face will require remedial support, likely in the form of shotcrete and rock bolts, and possibly a concrete portal extension if the slope above the portal produces runoff and rockfall. An access road will have to be constructed to the outlet portal area from the vicinity of the White River delta. The 32-inch-diameter steel surface penstock will transmit the water through the tunnel to _ the powerhouse. Support for the penstock will be required along the entire length of the tunnel. 2.2.3 Tunnel The 2,700-foot-long access tunnel will have an excavated dimension 8 feet width and 4-foot Tadius above springline. The alignment is tangent on an approximate azimuth of E-W and the slope of the tunnel is constant at 1.48 percent between the base of the shaft (elevation 200 feet) and the outlet portal (elevation 160 feet). Tunnel ground conditions are expected to be very good for drill-and-blast excavation. Bedrock consists of regionally metamorphosed phyllite and schist further altered by contact metamorphism around a large quartz diorite intrusion, with some veins and dikes of quartz diorite. Short sections of blocky ground related to faults, possibly with localized high water inflows (>500 gpm), are also anticipated. Cover is greater than 200 feet along almost the entire length of the tunnel, and reaches a maximum of 1,650 feet at the shaft. . The overall good quality of rock mass will allow for long sections of the tunnel to be left unlined, with only light support required for safety reasons. 2.3 Excavation, Initial Support, and Final Lining This section presents the expected tunneling conditions along the proposed route, including initial ground support and final lining for the drill-and-blast (0+B) method of excavation. Estimated construction quantities and costs are presented in Table 1. Anticipated geologic conditions are presented in Section 1.2, and on the cross-section in Figure 2. The latter also depicts the expected ground conditions and required support methods as bar graphs. This information is preliminary, and requires further investigation by borings and seismic surveys to be performed during a future design effort. The tunnel excavation setup will likely consist of the following: > A six person crew using jacklegs for the drilling of blast holes and rock bolt holes. 6 W-6527-01 SHANNON &WILSON. INC. > A small rubber-tired front-end loader to muck the tunnel. > A dry-mix pot to place shotcrete. > Compressors at the portal for ventilation fan and air for the jacklegs at the face. > Electric plant at the portal for lighting in the tunnel. > Shared field office and support facilities with the powerhouse construction crew. > Raise bore equipment. Mucking of the shaft excavation will be with the same equip- ment as used in the tunnel construction. 2.3.1 Excavation and Support at the Outlet Portal Talus and colluvium will be removed and the portal established where there is a minimum of 10 feet of rock cover over the crown of the tunnel. The face will be squared-off and the brow above the crown stabilized with rock bolts and shotcrete for stability and safety measures. An extended portal structure consisting of multiplate and concrete may be required to protect the work activities from rockfall and runoff above the portal. Excavation in from the portal will be full-face in rounds of 5 feet length, becoming gradually longer as the effects of weathering decrease and ground cover and rock mass quality increase. Areas of low rock cover and weathered blocky ground will require heavy initial support consisting of rock bolts and 10 cm of shotcrete, and locally steel sets and shotcrete. Again, initial support requirements will decrease as weathering effects decrease and ground cover becomes higher. The outlet portal area is logged as Ground Type 3 on Drawing 2. > 2.3.2 Tunnel Excavation and Initial Support In from the outlet portal where the rock is to some degree weathered and de-stressed leading to a loosened, blocky condition (support category 3), the greenstone is classified as slabby to slightly blocky tunneling ground along most of the tunnel. Weathering ceases to be a consider- ation where ground cover is greater than about 200 feet, and joints become fairly tight at about the same depth. Very localized blocky fault zones will occur, however these do not present significant problems for excavation except where they coincide with high water inflows. The latter condition (blocky ground and high seepage rates) probably only occur beneath large permanent streams or in large fault zones fed by streams. Some stress slabbing in the sidewalls may occur in areas of high cover (>1,000 feet) where steep joints parallel to the bore also occur, requiring additional rock bolt support. Rock mass characteristics for the tunnel have been divided into three categories: 1) massive, unweathered rock mass with minor seepage at the face (< 100 gpm) 4 W-6527-01 SHANNON &WILSON. INC. 2) heavily jointed rock mass or highly weathered ground, and/or significant seepage at the face (100 to 500 gpm) 3) wide shear or fracture zones or highly weathered ground, and/or high seepage inflows at the face (>500 gpm) Whenever required, the initial support requirements follow a similar categorization: 1) no initial support to local rock bolts placed in the crown and sidewalls to stabilize localized blocks or slabs of loose rock 2) rock bolts placed on a pattern supplemented with several centimeters of reinforced shotcrete in small blocky fault zones or weathered zones at the portals 3) __ steel sets encased in shotcrete at the portal or in large blocky fault zones, shear zones, or at the portal, especially those with high seepage inflows Rock bolts will be 5 feet in length, untensioned and anchored full-length with epoxy resin. At the portal face, longer bolts may be required as spiling. Shotcrete will be fiber-reinforced and placed in layers of 2 inches to the desired final thickness. Steel sets will be equivalent to W4-13 horseshoe ribs and will likely be required only in blocky fault zones with high seepage where shotcrete will not stick, or for a short section of the portal. 2.3.3 Final Lining Since the tunnel is required only as temporary access for the shaft excavation and for placement and inspection of the steel penstock, it need only be lined for ground support that is meant to stop progressive loosening and collapse of the rock mass. The final lining will therefore consist of the same elements as the initial supports, with greater thicknesses of shotcrete and closer spacing of rock bolts. No additional steel sets will be required for final lining. 2.3.4 Intake Shaft Excavation and Support The shaft excavation (4-foot-diameter) will consist of the boring of a pilot hole from a concrete reaction pad at elevation 1850 down to the end of the tunnel at elevation 200, and lifting a raise borer to the reaction pad. Muck produced by the raise bore excavation will drop to the tunnel level, and be removed by small loader. No initial support will likely be required for the shaft. Final lining will consist of the embedment concrete or grout placed around the annulus of the pressure pipe centered in the shaft. 8 W-6527-01 SHANNON & WILSON. INC. 2.4 Design Level Explorations 2.4.1 Geotechnical Mapping and Trenching Once the layout is set, site-specific mapping (microgeology) of the portal and shaft areas should be performed at a scale of 1-inch = 200 feet. Some trenching to expose bedrock may be required as part of this effort. Detailed mapping of features considered to be important rock mass defects such as fault zones, should also be performed. 2.4.2 Borings and Seismic Surveys A program of borings and surface reformation surveying should be performed once the results of the geotechnical mapping locates the important project sites (outlet portal, powerhouse, etc.) and larger scale rock mass defects (fault zones, etc.) that impact the project. SHANNON & WILSON, INC. GanyAlior P.G. Vice President William T. Laprade, C.E.G. Associate WTL:GM/Ikd 7-22-93/W6527-01 .RPT/W6527-lkd/lkd 9 W-6527-01 TABLE 1 } Tunnel Support Shotcrete Rock bolts, #7, 5 ft long Steel Sets, '4W13 Excavation/Initial Support Shaft 4 ft diameter 1,700 LF 7-16-93/TABLE. 1/W6527-Ikd/lkd SHANNON &WILSON. INC. sx. LS $300,000 50083 190,000 W-6527-01 TAL, \ ntake Da / \ \ 710 to 15 Feet High . OTT W. Elev. 1950 Ft. Mahoney Lake Hydropower Project Ketchikan, Alaska LEGEND SITE PLAN NOTE . —>— Avalanche Shute July 1993 W-6527-01 COE map provided by Cape Fox Corp. Contour Interval = 40 Feet SHANNON &) WILSON, INC. | FIG.1 | Geotechnical ronmental Consultants Skyline Fault Ground Surface Elevation in Feet & Phylite and Schist Foliation Tributary Shagft . Chamber: o oa > ° £ 3 = So a LY Gr. El. 160' < Quanz Phyllite/Schist and Diorite Quartz Diorite (?) Intrusive ® (3) _ Support Categories @ ® ® @ (2) Rock Mass Catagories ® @® 0 400 800 aS Scale in Feet HDR, Inc. Mahoney Lake Hydropower Project ESTIMATED SUPPORT CATEGORIES Ketchikan, Alaska @ None to spot rock bolts @ Pattern rock bolts and shotcrete TUNNEL PROFILE ® Steel sets and shotcrete July 1993 W-6527-01 SHANNON & WILSON, INC. | FIG.2 | Geotechnical and Environmental Consuttants SHANNON & WILSON. INC. APPENDIX TA: IN GEOTECHNICAL ENGINEERING REPORT W-6527-01 aoe SHANNON & WILSON, INC. Attachment to Report Page 1 of 2 oem Geotechnical and Environmental Consultants Dated: _Julvy 22, 1993 00 Important Information About Your Geotechnical Engineering/ Subsurface Waste Management (Remediation) Report GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND PERSONS. Consulting geotechnical engineers prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the geotechnical engineer/geoscientist. AN ENGINEERING REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. A geotechnical engineering/subsurface waste management (remediation) report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope- of-service limitations imposed by the client. To help avoid costly problems, have the consulting engineer(s)/scientist(s) evaluate how any factors which change subsequent to the date of the report, may affect the recommendations. Unless your consulting geotechnical/ civil engineer and/or scientist indicates otherwise, your report should not be used: 1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); 2) when the size, elevation, or configuration of the proposed project is altered; 3) when the location or orientation of the proposed project is modified; 4) when there is a change of ownership; or 5) for application to an adjacent site. Geotechnical/civil engineers and/or scientists cannot accept responsibility for problems which may occur if they are not consulted after factors which were considered in the development of the report have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural changes or human influence. Because a geotechnical/waste management engineering report is based on conditions which existed at the time of subsurface exploration, construction decisions should not be based on an engineering report whose adequacy may have been affected by time. Ask the geotechnical/waste management consultant to advise if additional tests are desirable before construction starts. For example, groundwater conditions commonly vary seasonally. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/waste management report. The geotechnical/civil engineer and/or scientist should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST GEOTECHNICAL RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help minimize their impact. Retaining your consultant to observe subsurface construction operations can be particu- larly beneficial in this respect. A REPORT’S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your geotechnical engineer’s report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Because actual Page 2 of 2 subsurface conditions can be discerned only during earthwork, you should retain your geotechnical engineer to observe actual conditions and to finalize conclusions. Only the geotechnical engineer who prepared the report is fully familiar with the background information needed to determine whether or not the report’s recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The geotechnical engineer who developed your report cannot assume responsibility or liability for the adequacy of the report’s recommendations if another party is retained to observe construction. THE GEOTECHNICAL ENGINEERING/SUBSURFACE WASTE MANAGEMENT (REMEDIATION) REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnical engineering/subsurface management (remediation) report. To help avoid these problems, the geotechnical/civil engineer and/or scientist should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological and waste management findings and to review the adequacy of their plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE ENGINEERING/WASTE MANAGEMENT REPORT. Final boring logs developed by the geotechnical/civil engineer and/or scientist are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnical engineering/waste management reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To minimize the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/waste management report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report’s limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes which aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnical engineering/subsurface waste management (remediation) is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against geotechnical/ waste management consultants. To help prevent this problem, geotechnical/civil engineers and/or scientists have developed a number of clauses for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the engineer’s or scientist's liabilities to other parties; rather, they are definitive clauses which identify where the engineer’s or scientist’s responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your engineer/scientist will be pleased to give full and frank answers to your questions. The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland 1/93 U.S. Army Corps of Engineers Geotechnical Information APPENDIX B FOUNDATIONS AND MATERIALS Table of Contents GENERAL GEOLOGY REGIONAL GEOLOGY . SITE GEOLOGY SEISMICITY PREVIOUS INVESTIGATIONS FOUNDATION CONDITIONS Damsite Lake Tap Penstock Tunnel Portal Surface Penstock Powerhouse MATERIAL ‘SOURCES Powerhouse Stream Damsite Quarry Disposal Sites CONCLUSION Figures B-1 Earthquake Epicenter Map B-2 Regional Geology B-3 Site Geology B-4 Stereographic Plot of Primary Joint Attitudes B-5 Geologic Section Through Tunnel and Penstock . Alignment Modified Mercalli Intensity Scale wo oa Table B-1 Maximum Peak Bedrock Accelerations at the Mahoney Lakes Appendices APPENDIX B-1 Tests on Gravel from the Powerhouse Stream APPENDIX B-2 Tests on Damsite Quarry Stone PODDDBDMDDIDH ~~ oa o 1 Ses Sos Qa DADNHWwWW Ww B-11 APPENDIX B FOUNDATIONS AND MATERIALS GENERAL. GEOLOGY Southeastern Alaska is part of the circum-Pacific "ring of fire," a belt of seismic and volcanic activity. The region, which includes Mahoney Lake, has been tectonically active since early in the Paleozoic era and has a complex geologic and structural history. It is divided into nine distinct geotectonic terranes, or groups of formations. Each: terrane is bounded ‘by faults and each has a-unique stratigraphic sequence. The terranes reflect an extensive history of large scale tectonic transport, continental accretion, crustal subduction, metamorphism, magmatic intrusion, and local disposition of volcanic and sedimentry rocks. Faulting has played a major role in the structural development of south- eastern Alaska. Large scale faulting, particularly right lateral strike- slip movement, has been common. Active faults.and major lineaments are shown on the earthquake epicenter map, Figure B-1. The trends of many of southeastern Alaska's inlets, waterways, straight valleys, and coastlines reflect episodes of major faulting. The two most prominent fault systems of southeastern Alaska are the Denali and the Fairweather-Queen Charlotte Islands faults. The Denali fault system is a great arcuate series of faults extending more than 1,000 miles subparallel to the Gulf of Alaska far to the north of the site. The Fairweather-Queen Charlotte Islands fault system extends southeastward from Yakutat Bay to the Queen Charlotte Islands, a total distance of about 650 miles. A few large and many moderate and small earthquakes have been generated by the Fairweather-Queen Charlotte Islands fault system. Most of the small scale landforms of southeastern Alaska are the result of glaciation during the Pleistocene epoch. Continental glaciers attained great thicknesses, as much as 3,000 feet, and rounded the peaks of many mountains in the region. Possibly, ice depths were as much as 5,000 feet in eastern Revillagigedo Island. Many glaciated areas later experienced uplift resulting from the gradual disappearance of the overlying ice. At present, Glacier Bay, to the north, is experiencing one of the fastest rates of uplift in the world, 1.5 inches per year. No glaciers are on Revillagigedo Island, although snowfields may persist at higher elevations and in shaded valleys. The present relief, classic U-shaped valleys, cirques, aretes, and hanging valleys, is a result of later alpine glaciation following the Pleistocene continental glaciation. REGIONAL GEOLOGY The region is in the Cretaceous Wrangell-Revillagigedo metamorphic belt that trends northwest across Revillagigedo Island. The degree of inetamorphism increases from west to east. The eastern contact with the coast range batholith is indistinct and consists of a broad belt of gneisses and Jurassic or lower Cretaceous intrusive diorites. 60 MILES 100 KILOMETERS Oo Mi ‘ ey iit an Klaas Ph _o a GRAHA LEGEND ————— HIGH ANGLE FAULT —4-4_4. THRUST FAULT Dotted where concealed ; queried where uncertain ————— LINEAMENT MAGNITUDE MAGNITUDE MAGNITUDE MAGNITUDE > ~~O—MAGNITUDE or not determined Note: Includes known or inferred events from 1899 to present. References Adapted from Berg and othe Heals. We. of the Ketchiken and Prince Rupert Quadr: Me en Report T0734. 1978; Berg and others. ot Elements of Insular Bell Coast Range Plutonic Complex near Ketchikan, Alaska, USCS Circular 151-0, 1976; Lemke, R. W., Reconnaissance Engineeri of the Ketchikan A: -- USCS Open File Report 75-456, 1994; NOAA 1 File for Epicenters to adit 1980; Pacific Geoscience Cent 1899 - 1977, Sidney, B. EARTHQUAKE EPICENTER MAP AIVERG AMD HARBORS ALASKA SOUTHEAST HYDROELECTRIC POWER INTERIM AGHFPP 2263-85 The region within about 12 miles of the project site contains three tectono-stratigraphic terranes that generally trend northwesterly. The terranes from southwest to northeast are the Annette subterrane and the Gravina-Nutzotin Belt, which are described briefly, and the Taku terrane, which is pertinent to the project area. On the regional geology map, Figure B-2, the Annette subterrane occupies the extreme southwest corner of the map. This subterrane consists of a heterogeneous assemblage of Devonian age and older intrusive, extrusive, clastic, and carbonate rocks. The assemblage records episodes of volcanism, magmatic intrusion, and sedimentation that began early in the Paleozoic era. The subterrane has been complexly deformed and metamorphosed. The Gravina-Nutzotin Belt consists of upper Jurassic to lower Cretaceous volcanics, sediments, and dioritic to ultramafic plutons. This assemblage has been identified as the remnants of a collapsed upper Mesozoic volcanic arc. Regionally, it is metamorphosed to greenschist facies and is folded into southwest converging, locally refolded isoclines with axial surfaces dipping moderately northeastward. The Taku terrane, within which the project area is located, consists of upper Paleozoic and lower Mesozoic volcanic and sedimentary rocks. The terrane is intruded by upper Cretaceous dikes, sills and stocks of granodiorite, a batholith of Cretaceous quartz diorite, and other plutons ranging in age from Late Jurassic to Miocene. The terrane is characterized by metamorphism increasing northeastward from greenschist to amphibolite facies of upper Cretaceous age and older. Locally, there is contact metamorphism near the edges of plutons up to the hornblended- hornfels facies. Structures include northeast dipping thrust faults cut by younger high angle faults. The stratified rocks are complexly folded into southwest overturned to recumbant folds and locaily refolded isoclines. The northeast boundary of this terrane is near Behm Canal, where it is in contact with elongate stocks of quartz diorite emplaced along a Mesczoic shear zone that is the contact between the Taku terrane and the adjacent Tracy Arm terrane. Surficial deposits include drift, elevated marine deposits, alluvium, fan- delta deposits, beach deposits, talus, and landslide debris. Faults and lineaments are common throughout the area and many topographic features reflect these structural elements. Some of the lineaments are associated with jointing and foliation planes that have been emphasized by glacial scour. Four major structures in the region are the Fairweather-Queen Charlotte Islands fault system, the Chatham Strait fault system, the Clarence Strait lineament, which may reflect faulting along all or part of its length, and the Coast Range linement, at least part of which is the result of faulting. Clarence Strait and Chatham Strait faults may be continuations of the Denali fault system of Southcentral Alaska and are, as such, associated with the North Pacific subduction zone. Recent investigations indicate as much as 120 miles of total right lateral movement. This is based on offsets of major features on opposite sides of the faults. B-3 LEGEND Qu Qh Ting Tngd Kg. Kpq Kum Kis Kv TRy TRiv val s Mere MaPed MePes MePav ay Salt . 6 Z . 7 Pam Laguon 4, RU § Coasy- Guard Kk RON De oI y SS ats Nin BP Aye sat Santon taxes Man o a. a ck abi ti REGIONAL GEOLOGY aunt RIVERS AND HARBORS mm ALASKA PERLE | sourwaasr nvononectmc rowan inven a Ct Major faulting is common throughout the area and many topographic features have been controlled by the presence of great fractures and intersecting fracture systems. -The locations of many erosion features, such as stream valleys and fjords with their abrupt changes of direction, are due Primarily to such planes of weakness. SITE GEO!.0GY As shown on the site geology map, Figure B-3, the project site is underlain by two major rock units. The bulk of the site, to the west and north of Mahoney Lake, consists of steeply dipping sediments (MP2s), which have undergone greenschist to hornblende-hornfels grade metamorphism. The Proposed sites for the lake tap, the tunnel, and the dam are all within the metasediments (metamorphosed sedimentary rocks), which have ‘been classified as sericite schist on the basis of thin-section analysis. The second major unit is a large intrusive body (stock) of quartz-diorite. The body is located on the south and west sides of Mahoney Lake. The lower portions of the surface penstock and the powerhouse site are underlain by quartz-diorite bedrock. The metasediments are part of the Wrangell-Revillagigedo metamorphic belt that trends northwestward across Revillagigedo Island. The bedding planes strike mainly north-northwestward and dip steeply westward. Thicknesses of the individual beds, where measured, range from 1 to 18 inches and perhaps more elsewhere. Figure B-4 presents stereographic plots of joint attitudes that were measured during field reconnaissance. Jointing occurs at various attitudes but the dominant set is parallel with the bedding planes. Secondary joints often strike northeastward and dip southeastward. The rock is generally hard, unweathered, and strong but tends to part along preferred cleavages... Iron staining due to weathering of large pyrite crystals within the rock can be observed at outcrops. The metasediments are intruded by granitic dikes and veins that are somewhat more frequent toward the east. The granitic rocks at the site are related to the northwest trending Admiralty-Revillagigedo intrusive belt. The belt contains bodies of granodiorite porphyries, quartz diorites, and diorites. Where exposed at outcrops, the rocks are hard and fresh. Petrographic analyses of bedrock samples confirm the classification of the intrusive body as quartz diorite. Because of its limited exposure at the site, preferred jointing or foliation in the rock has not been identified at this time. In general, bedrock is exposed or covered by thin, discontinuous surficial deposits throughout the higher elevations near Upper Mahoney Lake. The lower areas surrounding Mahoney Lake have both alluvium and talus that reach substantial thicknesses. : Surficial deposits observed during the reconnaissance fall into three categories: 1) talus, 2) alluvium, and 3) avalanche deposits. The distribution of these deposits is shown on the site geology map, Figure B-3. B-5 - CORRELATION OF MAP UNITS QahQts-Qed—quarannany cnaractous s DESCRIPTION OF MAP UNITS Qal ALU Siream aepenite oF send, 9m ont grovel ts awn, Rach ooste othe tens of 6 cA or mars, REI ting same Were tana of that 5 is Hf ih rit aa Contact betnnen ents. Arprosinttty ted, ie an pot Haat we shane tevsmne veteacton verve ow wu SITE GEOLOGY i i gr é 5 . i S Contoured lower hemisphere stereographic plot of the poles of 35 primary joint attitudes measured within the metasediments. A Kalsbeek counting net was used to develop the data. Contoured at: 2-53 TINT ; , STEREOGRAPHIC PLOT OF PRIMARY JOINT ATTITUDES 10-153 ei FIGURE RIVERS AMD HARBORS m ALASKA ee Comm SOUTHEAST HYDROELECTRIC POWER. INTERME B-4 Talus generally consists of angular, hard, and virtually unweathered boulders of metasedimentary rock ranging from several inches to masses up to 20 feet. Typically, talus is found at the base of steep slopes or cliffs. Talus-also includes scree, or loose material, lying on slopes without adjacent cliffs. Alluvium consists primarily of subrounded to angular fragments of metasedimentary: and intrusive rock. It is found in the stream draining Upper Mahoney Lake, other small streams, and in small fans where streams ‘enter Mahoney Lake. The alluvium is a mixture of silt, sand, and gravel. Several avalanche chutes are apparent in the Mahoney Lakes basin, as shown on Figure B-3.. These elongated areas are marked by a distinct lack of trees and by slopes covered with coarse, clastic rock fragments. Several faults and lineaments pass through the project site. Initial observation indicates that the stream flowing from the upper lake is fault controlled. Numerous north-south striking faults and fractures of various magnitudes pass through the east ridge. Two major features stand out because of their surface expressions. One fault, Skyline fault, has a much longer surface expression than other faults and crosses the projected tunnel alinement some 1,000 feet from Upper Mahoney Lake. One seismic survey line crossed the lineament but rock of varying seismic velocity was not detected. The fault surface is exposed approximately 800 feet north of the alinement and has a strike of N25E and a dip of 85° NW. The other fault, Portal fault, crosses the tunnel west of the portal and has the widest and deepest surface expression. It is through the trench of this fault that snow avalances. Its strike is N30E and its dip is 60° SE. The tunnel would pass under the trench to prevent avalanche damage to the penstock. There is no indication of recent movement along these faults and no seismic events are recorded anywhere for the area. The amount. and direction of offset on the faults are indeterminate. The geologic section through the tunnel and penstock alinement, Figure B-5, shows the projection of the faults onto the plane of the section. SEISMICITY Southeastern Alaska is tectonically and seismically active. - The boundary between the Pacific and North American crustal plates occurs along the southeastern Alaska coastline and movement of one plate relative to the other is responsible for coastal mountain building and seismicity. Major faults cross the region in generally northwest-southeast directions. Most are strike-slip faults with high dip angles, but thrust faults have also been recognized. Literature and data sources (Pacific Geoscience Center, 1980, and National Oceanic Atmospheric Administration, 1980) indicate no earthquake epicenters within 40 miles of the site since 1899. There have been two earthquakes of magnitude 5.0 or less within 50 miles, eight more of magnitude less than 5.0 within 100 miles, and one of at least magnitude 8.0 within 150 miles of the site. Earthquake epicenters in the region are shown on the earthquake epicenter map of Figure B-1. Most of the earthquakes appear to be associated with the Fairweather-Queen Charlotte Islands fault system, which lies approximately 140 miles southwest of the project area. The Fairweather fault extends from a point near Prince of Wales Island northwestward to Yakutat Bay. The largest recorded earthquake generated along the Fairweather fault had a magnitude of 8.6. The Fairweather fault is 160 miles from the Mahoney Lakes. The: Queen Charlotte Islands fault extends. southeastward from near the southeastern end of the Fairweather fault to the Queen Charlotte Islands, The largest earthquake generated along this fault had a magnitude of 8.1. This fault is 110 miles southwest of the Mahoney Lakes. The Chatham Strait fault is apparently either truncated by the Fairweather fault or is an offshoot of it. Historic earthquakes of magnitude 5.0 have been generated by movement on it, but judging by its _length, it is capable of producing earthquakes of magnitude 8.0. The Chatham Strait fault is 125 miles northwest of the Mahoney Lakes. Revillagigedo Island currently is considered to be in Seismic Zone 3. In Zone 3, earthquakes of magnitude 6.0 and greater can be expected. Its Proximity to large fault systems increases the earthquake probability, but the low level of recent activity shows the area to be relatively inactive. There are many lineaments in the region, although based on microearthquake data, none is the locus of recorded earthquakes. The intensity of shaking at the site would be a function of the amount of energy released by an earthquake, the distance to the epicenter, and. the geology of the site, particularly the extent and thickness of unconsolidated deposits. The largest earthquakes that could be expected on the active faults in the region and corresponding bedrock accelerations at the Mahoney Lakes area are presented in Table B-1. The most intense shaking would be generated by the maximum probable earthquake on the Queen Charlotte Islands.fault. Peak acceleration at the site due to that-event is estimated to be less than 5 :percent of. gravity; this roughly corresponds to a maximum intensity of about V or VI on the Modified Mercalli Scale given in Figure B-6. Upper Mahoney Loke W.L. Elev. 1954" a ° 5 = INTAKE CHAMBER g ELEVATION (Feet above MSL) Alluvium. Stream deposits of sand, silt, and gravel. Colluvium. Talus and slope debris (scree). 3000 3500 4000 DISTANCE (FEET) Quartz Diorite. Schist. Apparent dip projected from surface exposures. Fault. Apparent PORTAL Elev.683 SURFACE. PENSTOCK 5000 dip a. projected from nearby a exposures, where uncertain. REFERENCE: Topography taken from mop by R. W. Beck ond snseclaton, certain facility location information trom Corps of Engineers (inv. No, DACWS5) jt TREE RR RRT ERROR _~ Geologic contact, “approximate; queried RR can cl GEOLOGIC SECTION THROUGH TUNNEL & RHE a TE PENSTOCK ALIGNMENT LL-d Table B-1 Maximum Peak Bedrock Accelerations at the Mahoney Lakes Maximum Historical Maximum Credible Distance Maximum Credible Length Earthquake Earthquake2/ to Site Bedrock Acceleration3/ Fault (miles) Magn itudel/ Magnitudel/ (miles) (% of gravity) Fairweather : (offshore segment) 300 8.6 8.6 160 5 Queen Charlotte Island 350 8.1 8.6 110 5 Chatham Strait 200 5.0 8.25 125 5 1/ Magnitude refers to the Richter Scale. 2/ Magnitude credible earthquakes are based on correlation of earthquake magnitude and length of fault rupture in Greensfelder, Roger W., 1974, Maximum Credible Rock Acceleration from Earthquakes in California, Map Sheet 23, California Division of Mines and Geology. 3/ From Schnabel and Seed, July 1972, Acceleration in Rock for Earthquakes in the Western United States, Report No. EERC 72-2, Earthquake Engineering Research Center, College of Engineering, University of California, Berkeley, California. SS a nea MODIFIED — MERCALLI INTENSITY SCALE OF 1931 Not felt by people, except under especially favorable circumstances. However, dizziness or nausea may be experienced. Sometimes birds and animals are uneasy or disturbed. Trees, structures, liquids, bodies of water may sway gently, and doors may swing very slowly. E " Felt indoors by a few people, especially on upper floors of multi-story buildings, and by sensitive or nervous persons. © As in Grade 1, birds and animals aré disturbed, and trees, structures, liquids and bodies of water may sway. Hanging objects swing, especially if they are delicately suspended. ml Felt indoors by severat people, usually as a rapid vibration that may not be recognized as an earthquake at.first. Vibration is similar te that of a light, or lightly loaded trucks, or heavy trucks some distance away. Duration may be estimated in some cases. Movements may be appreciable on upper levels of tall structures: Standing motor cars may rock slightly. Iv Felt indoors by many, outdoors by few. Awakens a few individuals, particularly light sleepers, but frightens no one except those apprehensive from previous experience. Vibration like that due to passing of heavy, or heavily loaded trucks. Sensation like a heavy body striking building, or the falling of heavy objects: inside. i Dishes, windows and doors rattle; glassware and crockery clink and clash. Walls and house framtes creak, especially if intensity is in the upper range of this grade. Hanging objects often swing. Liquids in open vessels are disturbed slightly. Stationary automobiles rock noticeable. ; v Felt indoors by practically everyone, outdoors by most people. Direction can often be estimated by those outdoors. Awakens many, or most sleepers. Frightens a few people, with slight excitement: some persons run outdoors. Buildings tremble throughout, Dishes and glassware break to some extent. Windows crack in some cases, but not gener- ally. Vases and small or unstable objects overturn in many instances, and a few fall. Hanging objects and doors swing gencrally or considerable. Pictures knock against walls,-or swing out of place. Doors and shutters open or close abruptly. Pendulum clocks stop, or run fast or slow. Small objects move, and furnisiiings may shift to a slight extent. Small amounts of liquids spill from well-filled open containers. Trees and bushes shake slightly. vi Felt Oy area oes indoors and outdoors. Awakens all sleepers. Frightens many people: general excitement, and some persons * run outdoors. Persons move unsteadily. Trees and bushes shake slightly to moderately. Liquids are set in strong motion. Small bells in churches and schools ring. Poorly built buildings may be damaged. Plaster falls in small amounts. Other plaster cracks somewhat. Many dishes and glasses, and a few windows, break. Knick-knacks, books and pictures fall. Furniture overturns in many instances. Heavy furnishings move. Vil Frightens everyone. General alarm, and everyone runs outdoors. People find it difficult to stand. Persons driving cars notice shaking. Trees and bushes shake moderately to strongly. Waves form on ponds, lakes and streams. Water is muddied. Gravel or sand stream banks cave in. Large church bells ring. Suspended objects quiver. Damage is negligible in buildings of good design and constraction; slight to moderate in well-built ordinary buildings: considerable in poorly built or badly designed buildings adobe houses, old walls (especi- ally where laid up without mortar), spires, etc. Plaster and some stucco fall. Many windows and some furniture break. Loosened brickwork and tiles shake down. Weak chimneys break at the roofline. Cornices fall from towers and high pee Bricks and stones are dislodged. Heavy furniture overturns. Concrete irrigation ditches are considerably lamaged. Vill General fright, and alarm approaches panic. Persons driving cars are disturbed. Trees shake strongly. and branches and trunks break off (especially palm trees). Sand and mud erupts in small amounts. Flow or springs and wells is temporarily and sometimes permanently changed. Dry wells renew flow. Temperatures of spring and well waters varies. Damage slight in brick structures built especially to withstand earthquakes; considerable in ordinary substantial buildings, with some partia! collapse; heavy.in some wooden houses, with some tumbling down. Panel walls break away in frame structures. Decayed pilings break off. Walls fall. Solid stone wails crack and break scriously. Wet grounds and steep slopes crack to some extent. Chimncys.columns, monuments and factory stacks and towers twist and fall. Very heavy furniture moves conspicuously or overturns. IX ~ Panic is general. Ground cracks conspicuously. Damage is considerable in masonry structures built especially to withstand earthquakes; great in other masonry buildings - - some collapse in large part. Some wood frame houses built especially to withstand earthquakes are thrown out of plumb, others are shifted wholly off foundations. Reservoirs are seriously damaged and underground pipes sometimes break. x Panic is general. Ground, especially when loose and wet. cracks up to widths of several inches; fissures up to a yard in width run parallel to canal and stream banks. Landsliding is considerable from river banks and steep coasts. Sand and ‘mud shifts horizon- tally on beaches and flat land. Water level changes in wells. Water is thrown on banks of canals, lakes. rivers, etc. Dams. dikes, embankments are seriously damaged. Well-built wooden structures and bridges are severely damaged, and some collapse. Dangerous cracks develop in excelient brick walls. Most masonry and frame structures, and: their foundations, are destroyed. Railroad rails bend slightly. Pipe lines buried in earth tear apart or arc crushed endwise. Open cracks and broad wavy folds open in cement pavements and asphalt road surfaces. . i XI Panic is general. Disturbances in ground are many and widespread, varying with the ground material. Broad fissures, earth slumps. and land slips develop in soft, wet ground. Water charged with sand and mud is ejected in large amounts. Sea waves of signi- ficant magnitude may develop. Damage is severe to wood frame structures, especially near shock centers, great to dains, dikes and embarkments, even at long distances. Few if any masonry structures remain standing. Supporting picrs or pillars of large, well-built bridges are wrecked. Wooden bridges that “give” are less affected. Railroad rails bend greatly and some thrust endwise. Pipe lines buried in earth are put completely out of service. XII Panic is general. Damage is total, and practically all works of construction are damaged greatly or destroyed. Disturbances in the ground are-great and varied, and numerous shearing cracks develop. Landslides, rock falls, and slumps in river banks are numer- ous and extensive. Large rock masses are wrenched loose: and torn off. Fault slips develop in firm rock, and horizontal and vertical offset displacements are notable. Water channels, both surface and underground, are disturbed and modified pestly: Lakes are dammed, new waterfalls are produced, rivers are deflected, etc. Surface waves are seen on ground sur- faces. Lines of sight and level are distorted. Objects are thrown upward into the air. MODIFIED MERCALLI INTENSITY SCALE Saae Ses, Ue: PREVIOUS INVESTIGATIONS Numerous reports on potential hydropower sites-for Ketchikan and the surrounding southeastern Alaska area were initiated as far back as 1947. The first report specifically concerned.with the Mahoney ‘Lakes was by R.W. Beck and Associates entitled Swan Lake, Lake Grace, and Mahoney Lake Hydroelectric Projects, June 1977. A contract with Harding-Lawson . _. Associates for a Geologic Reconnaissance for Mahoney Lake Hydroelectric Project, Ketchikan, Alaska was completed in March 1981 and-provided an assessment of geologic conditions at. the project area. Additional field investigations by Alaska District Corps of Engineers geologists provided more specific data concerning various project features. FOUNDATION CONDITIONS Damsite The damsite would be located near the outlet of Upper Mahoney Lake. This valley is V-shaped with relatively steep sides and virtually no flat area in the streambed. .Bare rock is exposed on the east side of the valley. The west side of the valley is blanketed with talus deposits that consist of angular rock fragments ranging from coarse sand to cobbles. In the streambed, there are occasional large boulders up to several feet’in diameter. Based on a seismic refraction survey, the talus is generally about 20 feet thick at the left abutment and probably varies slightly from place to place. The talus is probably extremely permeable and would not Provide a stable and firm foundation for the dam. Bedrock at the site is a jointed metasedimentary rock of quartz sericite schist composition. Due to the scouring action of the glacial ice, most weathered rock has been removed. It is possible that very little bedrock would need to be removed for the binwall structure foundation. However, it has been assumed that 2 feet of rock would be removed for the foundation structure. The two existing talus slopes on the left abutment would be removed to construct the dam foundation and for fill of the binwall structure. The two talus slopes contain an estimated 10,000 cubic yards of rock, more than enough to fill the binwall. On the left abutment, the bedding planes dip into the ridge, producing an over-steepening effect of the slope. Freeze-thaw action in the rock is probably the most dominant weathering element that causes the rocks to slab off. Bedding and principal joints strike N30E and dip steeply to the west, or roughly parallel to the east side of the valley. Secondary jointing is prominent and due to multiple direction stress relief. Joints that are slightly open at the surface could be paths for seepage to several feet below the surface. Most potential seepage would be eliminated by keying the dam into the foundation from abutment to abutment, a maximum of 5 feet into bedrock. At the damsite, three prominent secondary joint set attitudes were noted on each side of the river. The dips of the individual joints in the joint sets and the relationship of one joint to another are similar on each side B-13 ‘of the river. One joint set has-been rotated approximately 30° compared to the other set. The river downstream of the damsite has a 200- to-300-foot, 90° offset. The offset occurs where the Skyline fault intersects the river ’ that drains Upper Mahoney Lake. A-waterfall is.near the.offset in. the river ina peeeven of the river. that has a uniform gradient, | The joint set rotation, the river offset, varid waterfall suggest pivitol rotation of the geclogic: units: at the damsite. on one side of the river compared to the other. The individual joints in the joint sets dip steeply -and appear open at the surface. The steep dips and probable rotation suggest that the joints may be open at depth. -Another prominent joint : attitude that is present only. at the damsite strikes east-west and dips 70° south.: This jointing was.open at the surface and would probably also.be open at depth. Aerial photography and slickensided primary joint surfaces suggest a fault/shear zone trending N30E and dipping west. This is the attitude of the primary bedding plane jointing. The rotation of the geologic units on one side of the river compared to the other also indicates faulting. This possible fault and the Skyline fault intersect near the waterfall and river offset. The metasedimentary bedrock is hard and excavations would require blasting. -Unretained temporary cut slopes as steep as vertical would be stable except where they would undermine slabs of rock on the right abutment. . Cuts steeper than the existing slope could Jead to block-glide failure of rock parallel to the existing slope. Once the dam were constructed, the rock spailing would cause minimal damage; however, some treatment of the abutment for safety during construction would be required. Other Corps projects with similar conditions were protected by using wire mesh and sufficient rock bolts, to hold the mesh in place. Talus and alluvium at the site and further downstream are sources of rock fill for the dam. Fine grained material for an impervious core is not available at the site. Riprap.for shore protection could be developed by selecting larger sizes from the talus and alluvium. Talus and aliuvium at the dam site and nearby areas is not suitable for.use as concrete aggregate. Lake Tap The lake entry could be located about midway along the east shore of the upper lake in good rock between two northeast trending faults that are _ several hundred feet apart. The rock through which the entry would be. : drilled is thinly bedded, fine grained, hard and brittle phyllite. Bedding > strikes north-south and dips 54° to the west. Secondary pyritizaton has permeated much of the country rock. Bedrock is exposed nearly continuously on the slope above the lake and, based on previous investigations, is also exposed on the slope below the lake surface. The rock is jointed and the joints may be somewhat open to a depth of several feet beneath the ground surface. No adverse joints or fractures could be found in the rock above the lake and in the vicinity of the tap site, but slabs of loose rock, within several feet of the surface above the tap, could break off the stope without some sort of permanent support to stabilize potentially loose blocks. The site of the lake tap is not critical; any location within several hundred feet of that shown on the site geology map would be satisfactory. B-14 The multipipe scheme has been studied to the extent that it appears feasible. The Alaska District queried contractors and Waterways Experiment Station personnel about the feasibility and desirability of such a scheme. Danger from slab rocks sliding down and closing off the intake area is virtually nonexistent with this scheme. and the fractures: near the. bake . . ‘become less important. By using several pipes.to penetrate into the lake, loose slabs of rock would be stabilized by the pipes passing through the slab. ‘Studies and explorations of the tap area will be made-to assess the rock for the tap. During construction, as the tunnel approaches the lake: tap site, careful drilling ahead to the lake would-be done from the tunnel to locate fractures and to determine the lake bottom slope for final design of the rock trap and: intake angle. Fractures and joints.passing through the valve chamber of the multipipe scheme are of more concern than those near the lake, but possibly, the grouting used to’ seal the pipes would be» sufficient for ‘the. fractures near the lake. Penstock Tunnel : Based on surface exposures, the tunnel would be entirely-within metasedi- mentry rocks. The rock is hard, strong,.and jointed with spacing varying from a few inches to a few feet; however, the joints are likely to be fairly tight at depth. Some overbreak should be anticipated in the tunnel and may partially depend on the excavation method. Occasional. granitic dikes and sills have been mapped in the area, but do not appear to intersect the tunnel. Numerous small veins of silica can be found throughout the rock. The tunnel alinement intersects two faults at high angles as shown on Figure B-5. The faults are'less than one foot wide at surface exposures and could be paths for concentrated seepage, but the rock in general probably contains little ground water. The headwall of the lower basin has been oversteepened by glacial plucking. Special mountain climbing equipment and skills would be required to investigate the rock over that portion of the tunnel. The tunnel is the most convenient means of access to the tap area beneath the lake. A 17° slope is proposed for the penstock tunnel to-ensure adequate cover over the tunnel at the avalanche chute of. the Portal fault. Reduction of the tunnel slope would also require bridging the avalanche chute with sufficient height to allow snow to cascade through the trench -beneath the penstock bridge. The tunnel. was discussed with a contractor to get a better understanding of the difficulties of driving a tunnel at such a steep angle. The contractor felt that the steepness of a tunnel was a matter of selecting proper equipment and planning and therefore posed no particular problem. A 10-foot-diameter tunnel .would afford room for all phases of work. For a multipipe scheme, the tunnel length would be roughly 4,000 feet long. The manifold chamber would be located some 70 feet from the lake. In this scheme there would be no pressure tunnel. The kinds of support anticipated for the tunnel are rock bolts, mine ties, and limited amounts of shotcrete. Concrete is not expected to be used as a primary tunnel support material, but would be used in the manifold chamber for support of the manifold pipes and other equipment. Concrete could also be used at the portal for a tunnel closure structure. B-15 Portal The steep slope of the tunnel would place the outlet portal location at elevation 396 at the base of a prominent cliff, where the metasedimentary rock is less jointed than elsewhere. On the face of the cliff: there is no overburden or weak rock that would require special support. Figure B-3 shows the four secondary joints attitudes at the portal-site. The east-west striking joint with a vertical dip is the only joint that is Probably open at depth that would result.in-wedge faiture. West of the portal site’‘is the Portal. fault, which is a pronounced lineament on aerial photography. The fault strikes: N30E and dips 60° to the southeast, with a sharp and narrow fault zone less that 200 feet. wide. Fractured and broken rock should be expected between. the- surface and a 300- to 500- foot depth. Future exploration should determine the proximity of the Portal fault to the portal opening. As projected on Figure B-5, it passes within 300 feet of the portal at tunnel depth. Surface Penstock The penstock would be constructed on the surface between the tunnel outiet portal and the powerhouse. The.area is underlain by talus and avalanche debris, which contains rocks up to 20 feet in diameter. The talus has a thickness of about 25 feet near the portal and 10 feet at the base of the slope near the powerhouse site with some bedrock exposure along the penstock route. The talus is composed of loose fragments of rock that may have large voids between individual fragments, and thus would not provide suitable foundation support. Considering the size range of the talus, it would be extremely difficult to excavate with conventional equipment unless large blocks*of rock were first broken by blasting. The bedrock beneath the talus would provide suitable foundation support for the penstock. Powerhouse The powerhouse site is accessible by a brushed survey trail that begins where the upper creek enters lower Mahoney Lake and trends southwest for 500 feet. The powerhouse site is adjacent to an intermittent tributary stream channel and is 5 to 10 feet above flood stage for the stream channel. The alternate powerhouse site can be reached by walking approximately 1,500 feet upriver from lower Mahoney Lake. This site is adjacent to the river and in the flood way. Local geology at the powerhouse and alternate powerhouse sites consists of blocky unsorted alluvial and colluvial deposits primarily composed of avalanche talus debris. The debris overlies granitic and metasedimentary basement bedrock. A seismic refraction survey indicates the talus deposits range in thickness from zero at the contact with bedrock to 75 feet at the lake shore. The seismic refraction survey at the alternate powerhouse site indicated 22 feet of overburden. The unsorted talus-avalanche debris ranges from gravel to 20-foot boulders. Boulders and blocky talus form 50 to 75 percent of the unconsolidated deposits. B-16 By building the powerhouse into the toe of the hilt, stability problems could be: avoided. - Some talus may need to’ be removed, but ‘the underlying bedrock should be suitable for the foundation. The granite rock consists . of slightly metamorphosed schistose grandiorite. The metasedimentary rock consists. of carbonaceous quartz sericite schist. The.schist was derived ‘through low to medium grade contact metamorphism of geosyniclinal : sediments. The granodiorite intrudes, overlies, and postdates the schist beneath the powerhouse site. Contact relationships between. the schist and granodiorite are concealed and inferred from surficial deposit distribution. ‘Primary bedding within the schist strikes northeast-southwest and dips steeply to the west.- The jointing follows relict bedding. No aerial lineaments ‘due to faulting ‘were observed near the sites. ‘The alluvial deposits at the alternate site may be unstable in the event of an earthquake. The dynamic response of the foundation materials should be studied in more detail, so that the alternative site can be considered further. lie : . MATERIAL SOURCES Exploration for construction materials, particularly for concrete aggregates, has been a part of all investigations for the Mahoney Lake hydroelectric project to date. Although only moderate quantities are required, the accessible sources are difficult. to find and those that are available will require careful processing to. produce suitable material. Two sources were sampled and are considered to be the most feasible. Powerhouse Stream A fairly extensive deposit of sand and gravel exists in the alluvial deposits of the creek draining into lower Mahoney Lake. Laboratory tests and microscopic (petrographic) examination of the material show it to be acceptable for concrete aggregate, road surfaces, etc, if properly processed. See Appendix B-1 for these data. Access to the site would be via road. Damsite Quarry An extensive talus deposit is located immediately adjacent to the left abutment of the’proposed structure. . Laboratory tests and microscopic . (petrographic) examination of this material show it to be acceptable for concrete aggregate, rockfill, or riprap of limited sizes. See Appendix B-2 for these data. Extensive processing of this material would be required for concrete aggregates. Access to this source would be via helicopter. In géneral, it appears that the bulk of. any or atl rockfill and riprap could be produced from the damsite quarry source. Material for any roadways or pad areas could be obtained from the powerhouse stream site. B-17 There are-no local sources of cement or pozzolan,-se that all such materials would have to be imported from the continental United States. Further studies will.include, but. not be limited to, mix-designs, processiblility studies, temperature studies, freeze/thaw reaeee and exact quantity. ee of any source selected. . E | Disposal Sites Sufficient sites would-be available for disposal of tunnel wastes. Areas close. to the tunnel portal would be suitable it environmental constratnts were met. CONCLUSION In conc Tusion, the project’ appears: feasible based on the ‘information available. The engineering characteristics of the bedrock. should be assessed and additional explorations will be required. Future investigations should include drilling of two holes at the damsite and drilling of one hole each at the portal, powerhouse, Skyline fault, and lake tap. Foundation investigations, which are often hampered by difficult access and by erratic weather conditions, should be initiated early in the design memorandum phase. B-18 "APPENDIX B-1 ~ “FOUNDATIONS: AND MATERIALS : Tests on Gravel from the Powerhouse Stream NPDEN-GS-L = (82-C-118) 19 Jan 82 MAHONEY LAKE HYDRO hKeport of Tests on Gravel From The Power House Stream, Alaska 1. Scope: On 9 Nov 81, 1290 lbs of pit run natural gravel composed of twenty sack samples were submitted to NPD Lab for bulk gradation, concrete aggregate quality tests, and processing studies.: Analysis of the bulk gradation indicated the following: (1) 1.1/2" MSA could be produced, (2) the natural aggregate bebeaiae le significent quanity (20%) of flat particles, (3) rescreening of the 3-1. 1/2 and 1 1/2-3/4 inch sizes to meet gradation specifications was only minimally successful primarily due to the flat particle pieces, and (4) rodmill sand would be required. Aggregate Sastiey teats were made on the natural material. Follcwing completion of the bulk gradation and aggregate quality tests a processing scheme was devised to produce 11/2" MSA blended crushed and natural aggregate. Due to the relatively small size of the sample, the laboratory processing study may not be representative of full scale processing efforts. Detailed results are as follows: NPDEN-GS-L (82-C-118). 19 Jan 82 SUBJECT: Mahoney Lake Hydro 2. Bulk Gradation: Nominal Size a a NOMI NA] SAZ Cy eee eel Fao Ieee 6n=3" 3-15" 5-3/4" —«3/4"-No. 4 “Fines ‘Total a, Weight, lbs 216 385 209 252 228 1290 b. Percent, % -. 16.8 2928 ent 6e 2 1925 pee a7) 100.0 ‘c. Gradation-Percent’ Passing 5-inch . i 100 es : . 100 4-inch - i - 3-inch 0 100° 83 2 1/2-inch 82 / 78 2-inch 48 100 68 1 1/2-inch ; ‘ 12 98 i 57 l-inch 1 50 100 46 3/4-inch . 0 10 97 38 1/2-inch . 1 59 29 3/8-inch 1 35 100 25 No. 4 : 2 98 18 No. 8 ; 77 14 No. 16 , 55) 10 No. 30 ! 32 6 No. 50 : 14 D No. 100 i 7 1 F.M. - - - - 3.17 - 3. Aggregate Quality Tests (Natural Gravel) _Nominal Size la 3"-15" 135"-3/4" 3/4"-No. 4 . Sand Specific Gravity, BSSD 2.69 2.64 2.60 2.62 Absorption, % 0.7 Lies i 2a , 247 Los Anyeles Abrasion % loss:@ 100 rev - 5.2 - % loss @ 500 rev = 2209) - Soundness of Coarse Aggregate by Accelerated Freezing and haw ing SeR Ree eee % loss by weight @ 300 cycles. Flat and Elongated Particles % Flat by weight = % Elongated by weight - otal. % - NI nN ao oloo eee Silos oloo 1 NPDEN-GS-1 (82-C-118) 19 Jan 82 SUBJECT: Mahoney Lake Hydro _ 4. Processing: . ; Nominal Size a. Bulk Gradation Plus 3" 3"-15" 13"-3/4" . 3/4"=-No. 4 Lbs “| 216° 316** 209% 252% Percent |) le] |) oe 25.9 7° Wd . 20.6 td Stockpile ake a : ance ** 69 lbs of 3"-1s"' material .sampled for .petrographic examination. b. Primary Crushing: 1) Crusher: 18x24 inch jaw at 2 15/16 inch setting 2) Feed: lbs. 216 . 316 3) Product: . . ; ; Lbs || 83 351 68 23 Percent- |. 15.6, 66.0 12.8 4.3 c. Secondary Crushing: 1) Crusher: 18x24 inch jaw at 1 15/16 inch setting 2): Feed: lbs 83 351 3) © Product: Lbs 250 119* 47 Percent ST 2755 10.9 * Stockpile 119 lbs. d. Ternary Crushing: 1) Crusher: 18 inch Gyrotory at 3/4" MSA sett ing 2) Feed: lbs Primary . : 68 Secondary 250 3) Product: 7 Lbs 64 185* Percent . : 21.4 61.9 * Stockpile 165 lbs. e. Rodmill Sand: 1) Rodmill: 18 inch @ x 42 inch Drum 2) Feed: lbs Primary 23 Secondary 47 Ternary 64 20 3) Product: Lbs 4) Loss: | lbs Percent ® Stochyile. lov lbs Fines 228% 18.7 1.3 17 329) 50 SACIG7/ 17 50 160% 68 29.8 Total 1221 100.0 532 532 100.0 434 433 100.0 318 299 100.0 228 160 NPDEN-GS-L (82-C~118) SUBJECT: Mahoney Lake Hydro f. Product: ~ 1) Lbs iF Natural. ’ Crushed | Total - 2) Percent © Crushed, each nominal size Each.nominal size .. | 3) Total Processing Loss, Percent 209° “19 Jan 82 g- Gradation: Combined Crushed and Natural Gravel Size 2-inch 14-inch l-inch 3/4-inch 1/2-inch 3/8-inch No. 4 No. 8 No. 16 No. 30 * No. 50 No. 100 F.M. NPDL 1794 252 228 689 “119 185 160 464 328 437 388 1153 36.3 42.3 41.2 40.2 28.4 37.9 33.7 100.0 5.6 Nominal Size 14"-3/4" 3/4"-No. 4 Sand z % % Alt. No.l Pass Specs Pass Specs Pass _ Specs 100 100 94 90-100- 44 20-45 100 100 10 0-10. 98° 90-100 a = 62 = I 0-5 34 20-45 160 100 3 0-5 98 95-100 82 80-95 62 55-75 39 30-60" 19 = 12-30 8 2-10 2.92 2.40-3.10 hklind PP oSd ba tebe ae aay : - Cuhees Ch. Rain, Treilrh tt NPL SAUSAL LEO COL TFUR: Ta cea ees niet Vustoiseat 1 Noe WORKIN UICUEDS Hae & itt Ve Lae tet , $9 VERDE Pk! i9d2 fo} ee GD Neer 8 i Use x 1 tgepnece 694 Labi: 1 (fe Y ‘ be. . Wei. 1794 may Paul D. Hecht iunaary. The aggretate was composed of generally hard sound material. The principle rock _ype was a fine grained quartz-muscovite schist which was foliated. This produced an iggregate which was generally flut to elongate in shape with 9% of the coarse aggregate weting the CKD 3 to 1 ratio of a flat particle. Much of the material showed secondary sineralization with numerous veins of pyrite present in both the schist and the quartzite. iverage percent composition of the coarse aggregate was 91 schist and 9 quartzite. Percent sind composition was 61 schist, 13 quartzite, 16 quartz, 4 muscovite, 2 hormblende, 2 pyrite, magnetite and 1 gamet. Percent by Sieve Size wck & Minerals 1 1/2" 3/4" 1/2" No.4 No.8 No.i6 No.30 No.50 No.100 Pan Schist 96 93 89 85 84 82 80 65 39 18 Quartzite 4 7 1l 15 16 16 15 13 10 7 Quartz : 2 5 17 29 42 Muscovite : , 3 9 14 Homblende 1 5 6 Pyrite aL 4 5 Magnetite i 3 Garnet 3 5 LENGE H CHANGRE PER CENTE AGE. DAYS NCTE: Each curve represents average of See IMEN) ISymBpoul |) Ie COMBINATION SET NO High Alkali Cement bars PROJECT MAHONEY LAKE HYDRO DISTRICT Alaska AGGREGATE Low Alkali Cement | Pit run natural sand from Power House Stream, Alaska. HIGH -ALKALI CEMENT 1.0} .Na.O “Whitehall Cement Co., Whitehall, PA LOW-ALKALI CEMENT (), 48-Na;0 Blend of Oregon, Idaho, and Lehigh Type I & IT Cements Plotted: J.H. |W/0 No, Checked 82-C-118 REACTIVITY OF AGGREGATES WITH ALKALIES IN PORTLAND CEMENT Chief. Conce ere Brancr (MORTAR BAR METHOD) METHOD CRD-C-123 CORPS OF ENGINEERS -NORTH PACIFIC DIVISIGN TESTING LABORATORY REMARKS NED FORM JULY 49 365 a ¥ pF t i ‘ S CHANG EE PER CE Ht 3 0.03- SS - | . el -- = enieee se E Soe a a! wo ha vee AGE, DAYS NOTE: Baen curee represents: Wee a Ges PROGEST CONIBINATION é MAHONEY LAKE HYDRO DIST RT Aiiatcale AGGREGATE _ * Pit run ‘natural sand from Powerhouse Stream, Alaska. { High Alkali Gement Low Alkali Cement ant Trncat ERATE CEE int LOT fay Whitehall Cement Co., Whitehall, PA. a 2! 0.48 °. Blend of Oregon, Idaho, and Lehigh Type ! & IT Cements fund Ho ae cesta 82-C-118 - —— aed Ee JAMES K. HINDS . RELA TINITY OF AGGREGAILS WITEE ALKALIE GS iP) oR Tbr Chien (MORTAR 13.4 Mf Trt) AMCTHhOts CWE os 12733 CORPS OF ENGINEERS BORD Mihi DIN Db. TiS Tihs bbe cleat ce APPENDIX B-2 — FOUNDATIONS AND MATERIALS ‘Tests on Damsite Quarry Stone NPDEN-GS-L -. (82-C=118) — : ma . 25 -February 1982 MAHONEY LAKE HYDRO Report of Tests on Damsite Quarry Stone 1. Scope: On 09 Nov: 81, “1078 lbs of pit run quarry. stone composed of twenty sack samples. were submitted to NPD Lab for ‘bulk gradation, rock mechanic tests, processing studies, and aggregate quality tests. The sample was - generally flat and slab shaped with a heavily foliated structure. Numerous pieces also contained visable fracture planes. 2. A bulk gradation was made of the entire sample. Analysis of the bulk gradation indicated that 3" MSA could be produced and that ‘rodmill sand would be required. Following completion of the bulk gradation, approximately 173 lbs of the larger pieces of stone were removed for rock mechanic tests. A processing scheme was devised to produce 3" MSA. Due ta the flat angular structure of the rock, recycling of the crusher product was required to produce the 1 1/2"-3/4" size. Due to the relatively small size of the sample, the laboratory processing study may not be representative. of full scale processing efforts. Detailed results are as shown in Table I. 3- Tne larger size stones for the rock mechanics tests were cast in concrete prior to coring. Cores were drilled both normal and perpendicular to the Plane of foliation. NX cores were drilled where possible; however, due to the ‘small size of the stone most tests were made on 1 1/4" diameter specimens. Recovery of cores drilled -parellel and perpendicular to the foliation plane averaged 86 percent and 38 percent, respectively. Tests included splitting, tensile and compressive strength, modulus of elasticity and Poissons ratio. Where possible, four to five specimens were scheduled for each test. Detailed results are shown in Table II. NPDEN-GS-L | -(82-C-118) : a 02 Mar 82 . MAHONEY LAKE HYDRO DAMSITE TABLE I -Report. of Processing Studies and Aggregate Quality Tests on Quarry Stone lL. Bulk Gradat ion: Nominal Size : : — 3"—1 1/2" Total a. Weight, lbs 847 23k 1078 b. Percent, Z.- ~ . 78.6 21.4 . 100.0 c. Gradation-Percent Passing rs 9Q-inch _. . 100 . ; 100 6-inch . 91 5 93 ‘S-inch 47 . 58 4-inch 30 45 § 3-inch © =: 0 100 21 24-inch . a . 29 6 2-inch . . ll 2 l3-inch Sm 1 l-inch : 3 1 2. Processing: a. Primary ‘Crushing (1) Crusher: 18x24-inch jaw at 2 15/l6-inch setting (2) Feed: 898 lbs Pit Run 9" MSA . Nominal Size (3) Product Plus 3" 3°-1's"- 14"-3/4" 3/4"-No. 4 Fines Total (a) lbs 265 452* 108 45 21 891 (b) Percent : 29.7 50.7 Ze) Sal _ 2.4 100.0 * Stockpile: 250 lbs b. Secondary Crushing (1) Crusher: 18x24-inch jaw at 1 15/l6-inch setting (2) Feed: lbs” 265: 202° 467 (3) Product* . ; (a) lbs 2 155 209*%* + 14" 27 467 (b)- Percent . 0.4 3352 44.8 15.8 5.8 100.0 * Due to flat particle shape the plus 14-inch material from the initial crushing was recycled through the jaw crusher. Results are for the two passes. ** Stockpile: 180 lbs c. Ternary Crushing (1) Crusher: 18-inch Gyrotory at 3/4" MSA setting (2) Feed: lbs (a) Primary 108 (b) Secondary 2 1s5- 29 ; 294 (3) Product: oO (a) - lbs 78 166* 50 29- (b) . Percent 26.5 56.5 17.0 100.0 * Stockpile: 166 lbs . : 4. Rodmill Sand (1) Rodmill: 18-inch @x42-inch Drum (2) Feed: lbs . (a) Primary 45 21 4b) Secondary 74 27 . (c) ‘Ternary 78 - 50 295 (3) | Product: © (a) Ibs : 203 203 (b) Percent 3 100.0 100.0 (4) Loss: (a) lbs : : : oie 92 (b) Percent . : 31.2 NPDEN-GS-L (82-C-118) 02 Mar 82 SUBJECT: Mahoney Lake Hydro Nominal Size 15"-3/4" 3/4"-No. & Plus 3" 3"-15" Fines Total e. Product (1) lbs 250 180 _ 166 203 799 (2) Percent 31.3 22.5 20.8 25.4 100.0 (3) Total Processing Loss, Percent 10.3 3. Aggregate Tests-Processed Quarry Stone: Nominal Size a. Gradation Hgh=3/4" SE =Wos Ah) /lingend 2 z z % % Alt. Nol Size Pass Specs Pass Specs Pass Specs Pass Specs 4-inch 100 100 3-inch 98 90-100 24-inch 68 - 2-inch 37-20-55 106 100 14-inch 8 0-10 90 90-100 l-inch 2 O-5 28 20-45 100 =100 3/4-inch 6 0-10 97 90-100 1/2-inch 2 - 62 ad 3/8-inch 1 0-5 33 20-45 100 =100 No. 4 4 0-5 96 95-100 No. 8 81 80-95 No. 16 62 55-75 No. 30 41 30-60 No. 50 20 12-30 No. 100 7 2-10 F.M. 2.93 2.40-3.10 b. Specific Gravity, BSSD 2.74 2.74 2043 2.73 c. Absorption, 2 0.5 0.7 1.0 | d. Los Angeles Abrasion % loss @ 100 rev. = 3 6 % loss @ 500 rev. ' = eo ' e. Flat & Elongated Particles % Flat by weight % Elongated by weight Total w be oo im OO of w ¥ ° fi S| ° xjo~ oloo ' f. Soufidness of Coarse Aggregate by Accelerated Freeze-Thaw % loss by weight @ 300 cycles 0.4 - (2) NPDEN-GS-L__ (82-C-118) 25 Feb 82 MAHONEY. LAKE HYDRO DAMSITE TABLE II Summary of Tests on.Cores Drilled from Damsite Quarry Stone : : Tests a i 2¢ : : Cores Drilled Normal to Cleaverage Fisne = : pinetia Strength, . Tensile Compressive Modulne of Poisson's Core : (Brazilian) _ Strength, Strength, ar ai Ratio No. psi. . psi | pes. ExlO psi u ra Arlo 18958 - = _ 47,8108 | 9.19 0.161 A275 =e » 25,900 7.83 0.162 A390) = 580 - - - A=4 3860 - - - - B-1 2345 - 26,700 7.43 0.163 B-2 1625 - 19,640 - = B-3 1050 1155 - 1 — Fol ” 480 a = - = G-1 "2610 - - - - - G-2 2745 - a a = 3-1 - 285 61,500 8.79 0.144 J-2 - 65 - - - K-1 2255 - - - - K-2 3225 - - = - 1 - 360 - - - Average 2625 490 "36,310 8.31 0.158 High 4895 1155 61,500 9.19 0.163 Low 480 65 19,640 7.43 0.144 Std. Dev. 1290 415 17,640 0.82 0.009 c-1 - 1905 3/ S = = Cc-2 - - 28,960 11.44 0.204 c-3 - - 35,330 12.82 0.297 c-4 - - 11,050 - - D-1 - 1745 - - - D-2 “1120 - 12,460 10.22 0.326 D-3 1210 980 - - - E-1 3955* 1475 - - - E-2 3305* 1620 - = E-3 - - 35,170 10.38 0.189 H-1 - 610 - - - o-1 2465 - = = — s-1 1395 - — = = s-2 1430 - - - - Average 2125 1285 24,590 11.22 0.254 High 3955 1745 35,330 _ 12.82 0.326 Low 1120 610 11,050 10.22 0.189 Std. Dev. 1135 “475 12,010 1.20 0.068 NPDEN-GS-L (82-C-118) _ ok ear Ve _ 25 Feb 82 TABLE II - PPT VE) ele 7p | ok ee “|| =) 14 ; : MAHONEY LAKE HYDRO-Summary of Tests on Cores Drilled from Damsite Quarry Stone NOTES: _ ‘1/ Laboratory Test. Methods: a.. RTH 113-80, "Standard Method of Test for Determining the Splitting Strength. of Rock" (Brazilian Method) b.: RTH..112-80, "Direct Tensile Strength of Intact Rock Core Specimans" -(ASTM D2936-78) : oe : Cc. RTH.111-80,. "Unconf ined Compressive Strength of Intact Rock Core Specimans" (ASTM D2936-78) d. RTH.201-80, “Elastic Moduli of Rock Core Specimans in Uniaxial Compression" (ASTM D3148-79) In igs All tests on nominal 14-inch diameter cores. except as noted. 3/ Failure occurred through epoxy at end of core speciman, test result not included in computation of. average and standard deviation. * Test made on nominal 1- 3/4-inch diameter core. (2) NPDEN-GS-L. (82-C-118). ~, (02 Mar 82 MAHONEY LAKE HYDRO DAMSITE , TABLE’ I Report. of Processing Studies and Aggregate: Quality Tests on Quarry Stone 1.. Bulk Gradation: Nominal Size noe : . 1/2"° Total ‘a. Weight, lbs) : - BAT 231 1078 “b.. Percent, % ve : 78.6 (21.4 100.0 .¢. Gradation-Percent Passing . - . , * ‘9rinch ..° . 100 190 ‘6<inch . - 91 : - 93 S-inch 2: AT : 58 “ 4-inch . © ". ; - 30 45 » 3-inch, ne : = Oo. 100 2 24-inch. - 7 a : 29 6 ‘Qeinch «=. | 2 , oF “Oo 2 “Ya-inch © tae : . : 5 1 1 . l-inch : . = 3 ' 2. Processing: a. Primary Crushing (1) Crusher: 18x24-inch jaw at 2 15/l6-inch setting (2) Feed: 898 lbs Pit Run 9" MSA a : Nominal Size _ (3) Product Plus 3" 3"=-1"- V."-3/4" 3/4"-No. 4 Fines Total (a) ‘lbs | 265 452* 108 45 21 891 . (b) Percent 29.7 50.7 12.1 . 5.1 2.4 100.0 * Stockpile: 250 lbs : . b. Secondary Crushing (1) Crusher: ~ 18x24-inch jaw at 1 15/16-inch. setting (2) Feed:° lbs. 265 ° 202 467 (3) Product* . : . : (a) lbs 2 155 209%* 74 2? 467 (b) Percent - 0.4 S32 44.8 15.8 5.8 100.0 * Due to flat particle shape the plus 1,-inch material from the initial crushinz was recycled through the jaw crusher. Results are for the two passes. ** Stockpile: 180 lbs. a Ternary Crushing (1) “Crusher: 18-inch Gyrotory at 3/4" MSA setting (2) Feed: lbs (a). Primary . 108 . (b) . Secondary. 2 155 - 29 : 294 (3) Product: . (a) lbs.” 78 166* 50 294 . (b) Percent . 26.5 56.5 17.0 100.0 * Stockpile: 166 lbs : d. Rodmill-Sand (1) Rodmill: 18-inch $x42-inch Drum (2) Feed: lbs : (a) Primary . 45 21 (b) Secondary . 74 27 . (c) Ternary 78 - _, 50 295°: (3) Product: . . (a) lbs 203 203 (b) Percent 100.0 100.0 (4) Loss: : : (a) lbs 92 (b) Percent 31.2 NPDEN-GS-L_ (B2-C-118) 02 Mar 82 SUBJECT: Mahoney Lake Hydro . : Nominal Size Plus 3" 3%=15" 35"-3/4" 3/4"-No. 4 Fines Total e. Product . (1) lbs : 250 180 166. 203 799 (2)' Percent . * 31.3 22.5 _ 20.8 25.4 100.0 (3) Total Processing Loss, Percent . . . 10.3 3. Aggregate Tests-Processed rry Stone: : a‘ . - Nominal Size a. Gradation 3"—-155" 13"-3/4" 3/4"-No. 4 Sand — ! 7. . Z : z z % Alt. sol: Size : Pass ‘Specs Pass Specs Pass Specs Pass Specs i 4-inch 100 100 i 3-inch 98 90-100 i 24-inch 68 - t 2-inch 37. (20-55 100 100 ! V'y-inch “8 0-10 90 90-100 : l-inch 2 0-5 28 «20-45. = 100-100 | 3/4-inch 6 0-10 97 90-100 1/2-inch 2 - . 62° - 3/8-inch 1 0-5 33 20-45 100 =100 No. 4 “4 0-5 96 95-100 | No. 8 . . 81 80-95 No. 16 : 62 55-75 No. 30 41 30-60 No. 50 20 12-30 No. 100 7 2-10 FM. 2.93 2.40-3.10 b. Specific Gravity, BSSD 2.74 2.74 2.73 2613: ce. Absorption, % 0.5 0.7 - 1.0 ict ’ | d. Los Angeles Abrasion : % loss @ 100 rev. - 3.6 - % loss’@ 500 rev. - 16.1 - e. Flat & Elongated Particles , % Flat by weight 33.0 9.0 7.0 - % Elongated by weight 2.0 1.0 0.0 as Total 35.0 10.0 7.0 - f. Soundness of Coarse Aggregate by Accelerated Freeze-Thaw _ % loss by weight @ 300 . . cycles 0.4 : - (2) NPDEN-GS-L Core No. Al on A-2° eS A-4 B+1 _ B-2 B-3 ‘F-1 G-1 G-2- J-1 J-2 K-1 K-2 qe Average “High Low Std. Dev. C-1 c-2.. c-3- c-4 D-1 D-2 D-3 E-1 E-2 E-3 H-1 O-1 S-1 S-2 Average High © Low “Std. Dev. | (82-C-118) MAHONEY. LAKE HYDRO DAMSITE TABLE II 02: Mar 82 Summary of Tests on Cores Drilled from Damsite Quarry Stone: a a 7 Tests"—' 2+ : . Cores: Drilled Normal to Cleavage Plane = - Splitting — _' Strength, . Tensile Compressive Modulus of . (Brazilian). Strength, Strength, . Elasticity, pet le Pal Ps Exl0 "psi. 4gosee a 47 ,810* 9.19. 3775* - 25,900 7.83 - * 3580 - - - 3860 - = = 2345 - 26,700 7.43 1625 - 19,640 = 1050 1155 - = 480 - - - 2610 - oS > 2745 — od =) - 285 61,500 8.79 = 65 = S 2255. - - - 3225 - 2 = - 360 - = 2625 490 36.310 8.31 4895 ETSS) 61,500 9-19) 480 65 19,640 7.43 1290 415 17,640 0.82 Cores Drilled Parallel to Cleavage Plane** * 2465 1395 1430 - 2125 3955 1120 1135 1905 3/ = 5 28,960 = 35,330. - 11,050 1745 = = 12,460 980 ais 1475 - - 1620 z - 35,170 610 = 1285 24,590 1745 ° 35.330 “610 11,050... 475 12,010 11.22 12.82 10.22 1.20 Poisson's Ratio u 0.161- 0.162 0.158 0.163 0.144 0.009 0.254 0.326 0.189 0.068 DEPARTMENT OF THE ARMY wro Lab. No. 82/30H MISSOUR| RIVER DIVISION, CORPS OF ENGINEERS DIVISION LABORATORY 16 FEB 1982 OMAHA, NEBRASKA 68102 Subject: Petrographic Examination of Quarry Stone . Report Series No. 8° Project: Mahoney Lake Hydro Intended Use: Concrete Aggregate ee eemncinnrtiereeernntietitinnebierthtielinamerediienen Source of Materia}:_Mahoney Lake Hydro Damsite Quarry, Alaska Submitted by: Director, North Pacific Division Laborato - Date Sampled: _ — ~__, Date Received:_14 Jan 82 Method of Test-or Specification:__CRD-C_ 127-67 References: North Pacific Division Laboratory Request No. E85829504 dated d L O 82-C-118. SAMPLE IDENTIFICATION .- MRD Lab No. 82/30H. Sample of quarry stone for use as concrete aggregate taken from Mahoney Lake Hydro Quarry, Alaska. TEST RESULTS 1. Petorgraphic examination of the quarry stone reveals it to be a dark gray, fine-grained quartzo-feldspathic gneiss probably derived from a sandstone. The rock has a fairly well developed foliated structure in which quartz grains and lenses tend to have augen shapes. The feldspar, mostly orthoclase, is abundant in the rock and is generally finely crystalline.. It is closely associated with tremolite having a lineated trend. A small amount of chlorite is also present. Finely crystalline ‘magnetite occurs in the lines of schistosity. A considerable amount of pyrite is distributed throughout the rock as small crystal masses. The rock is fresh and hard, and appears to be durable. However because of oxidation of pyrite, the outer surfaces. are stained with brown iron oxide, especially along joint surfaces. The pyrite upon alteration to iron oxide may have a detrimental effect on concrete by producing stained Surfaces and possibly cause sulfate expansion. Particle shape may be a problem with this rock due to the closely spaced joint system. 2 itted by: ANA Ue fo R. K. SCHLENKER Director, MRD Laboratory MRD. FORM BRD/FORM 15 EDITION OF FEB 67 1S OBSOLETE. . teb NPDEN-GS-L (82-C118) iii a1} 02 Mar 82 TABLE I1 MAHONEY LAKE HYDRO-Summary of Tests. on Cores ‘Drilled from Damsite Quarry ‘Stone NOTES: 1/ Laboratory. Test Methods: “*a.: RTH-113- 80, "Standard Method of Test for Determining the Splitting Strength of Rock": Atvestitan Method) | i be RTH 112+ 80; ea Tensile. Strength of Intact Rock Core Specimans' (AST. '02936- ~78) Ce “RTH: 111-80, ‘“Unconfined Compressive Strength of Intact Rock Core Specimans" (ASTM D2936-78) : d. RTW 201-80, "Elastic Moduli of Rock.Core ne in Uniaxial Compression" (ASTM. D3148-79) 2/. All. tests on nominal’ Ly-inch diameter cores except as noted. 3/ Failure occurred through epoxy at end of core speciman, test result not included in computation of average and standard deviation. * Test made on nominal 1 3/4-inch diameter core. ** Revised 02 March 1982. (2) LENGTH CHANGER PER CENTS as !00 150 ?00 250 300 3€5 AGE, DAYS NOTE: Eacn curve represents avcrage ct tars PROJECT COMBINATION ne SFT N 1828 | @ High Alkali Cement ee ae eee j ! [ors Rit Alaska a 1828A s Low Alkali Cement AGURTUAIT : Laboratory manufactured sand from Damsite | | Quarry stone, Damsite Quarry, Alaska. ; Ri MARRS : [rad carent on tinil OL ioe > — i i| Whitehall Cement Co., Whitehall, PA | Pio diese eat O48 G Paty Blend of Oregon, Tdaho, and Lehigh Type | I & II Cements i i ae 1.H . ww OO am 7 7 ; 7 [Siero cic 82-C-118 | JAMES K. HINDS eh EE at ne Li aed REACTIVITY OF AGGREGATES Welit GALKALIES ih Pe oktliatvis CEMENT (MORTAR BAR MET#HOL) RHE TPO Sbgda es 8 1 LORPS OF ENGINEERS MORTH Pre tivtic tow EES bibsy Ai RAO | APPENDIX F HYDROLOGY INFORMATION HDR Engineering Hydrology Information Average Daily Flows 8 se8 acods zis gaae® Ss a, Re 8 Kee 8 B28 aerate g geal Fe. Rnaee at FRowo late ae kReleanta a a ANSK ro gBoes, CAR eRe RAGAR @RF2grzsshowgny thy gaaeg 2e®eqtaeRsaao gee ise sassy e8ASgtzaseyoa aR®BSgReanzagea 28RE5PQNRsyEe aeS2eRegaregs a®StoSangags aSESgRcoResar SRateRehgrax RS SS Qaarels2 ARSalaeasgegs “agaRoaogeanges Ra. ea ey’ Reta No eReS ‘a am RBig Fao ele ° -” RRng 8k Ae” Been IR RIA” BRL FE Rw” © gi BRM a ALK Ao BR2n= "so a8o* f88aym 8 ees Bau aye a NPZen ASSL AFR Bor Z5,, RAB Ven Rol2&m BIS. onRrarda EMR CwoeHoglge ARogesegretyr “agaenorineor 7 9 $8 8 10 12 16 IS 14 1 1 10098 777 8 12 8 3 WIS 7ul 13:12 12 13:17 B 2 17 14 14 13 12 1 10 9 eke iasinanata egaesizasts egkesteaats saves tsanks SHEBRSAAAAK 6 8 0 & 39 @ SS 49 95 8 GM 4 4 41 41 41 49 149 7 4 «0 3 iL 1 REESVSRE SRETTVARSE SRBRSRBCAR SR ERREALRG eSrRSHABASe 4 15 18 21 27 21 17 1S 18 2 6B 83 1317 10 16 12 9 1S 14 14 13 19 19 2 19 17 16 17 16 15 15 13 13 S97 6 OS (SS) 1S S36 26-45 5S 7: $388 8 9 8 8 777 9 10 14 M1 4444444444444 179 2B 91 7 48 49 $3 100 100 100 100 112 189 170 162 12 16 16 16 14 13 12 WM OU 1925 1 39 $8 S3 32 33 Sl 49 33 33 182 79 @& 72 @ 61 TI 9 134 21 7 106 16 88 94 107 761233 SB SS SS SB 6 16 21 2% 2% 2 17 15 1S 14 12 1 WO 9 4 18 17 17 17:15 14 14 13 ® 18 17 1S 14 oo 9 9M UM 219 16 15 13 3 ® 3% 47 44 2% 16 12 17 SB 47 ® 2 su 2? & 2-3 12 12 1423 7 37 2 714412212299 9121717 1412999 9 oi nm 37 7 131 71 38 2 1 s 12 12 u $5444 2 iz 3S 29 174 132 72 142 89 90 112 95 61 30 WD 12 9 763 ):4-S 3-333-446-4553 6 7 S18 8G (88888-9077 9 7 9 1 6 116 6 64 35 35 187 410 7 8 10 13 PNA eds Mecha eal gel ge Rea ete 66661 Ul i 1922 2 8 90 138 95 125 111 53 32 tq 8 e_,8aes eqaarse Sange antese ligase ageakagiaeace gqertslfaana g grshakiaran aghis*e®Asenr gnheSakesesr ay lietc4%eeara agtiek&eFenaner ahatekaaeer atRZeg8eRasea a@RgReSsRgng aBgBVSRsenes SVT SVRARLS PReRasSsaas 7666S S5 5 010099 9 8 8 g8laxaas ae aceaen SRARSRRBA ea ®eraaaee an ®eesaas an®eeenar- azv®eoxansd se®ecaaaad se cenaaad’ se ®eenaeae anfesneaes eRLSRRIRAK ae ® enase 39 91 49 34 9 74 12 12 12 12 12 12 12 12 12 12 12 12 12 33 33 33 33 33 33 33 33 33 33 33 33 12 33 «4 46 42, SS @ a7 35 a a 2 SAERAGHERABS TReEBSoRSeraga 9:9 9 9-9: 9. 9. 9..9. 9-9. 9:..9: 9.8 9 2 6 8 2232 8 aS 2 2 81 76 S39 2 W 17 S 12 12 11 18 2@ 18 14 12 13 16 18 16 13 12 10 1927 RRtaaRaRNRANDM is 12 wv 4193 10 32 39 399 399 27 17 12 «WN 8 14 14 14 14 14 14 14 14 14 14 14 14 S) 27 @ 7 7 7 wi 9 4 3 4 33 SB 6 HA 9 19 3% BD 93 80 129 118 175 171 @& S@433 3 3:33 8 223 7Ba DAB 18129765 5 84 WS 18S 96 135 162 6 36 93 85 m8 6 141 47E6-STIWVMWMUBBAwWM DA Dw 5 9817 7 7'6 7 € 6 6 6 $767 9 10 15 19 18 14 12 9 8 8 16 19 21 18 16 14 16 19 30 SS 45 37 142 248 12 ate sxa8? anageaggn? azngeaugg are 2ghegesagg ss Aghpssaasee Sabgerragte eehgseaae%s Rabgasage%s exngeeReate 2eRgeseRgaka 2Saserenaads HASBRRSIRR= 2SasgRressass LaRBRssRase AAsyRsRs Vans FeR_OVASARLA 9 9 13:17 35 B 2 2 2 19 17 1S 18 2% 21 7 16 14 14 12:11:10 «9 8 8 8 9 10 14 S4 52 6 33 33 33 33 33 33 33 27 2 17 16 18 17 1S 13 u wah SFE gatg eRRABAR gone rae iakOagne od. =&298 s i 7 Cy 3 13 17 16 1S 14 16 18 21 25 38 71 1 12 140 121 169 121 244 88 64 SS 41 S6 19 15 11 2 10 10 15 1S 15 17 26 113 89 75 69 143 189 148 102 a ReABHVGRSTNH 3 enn Segoreegs ing line. The above data are the average daily flows for the given water year. The months are numbered in the far left column (January is 1, February is 2, etc.) and the flows for each day within that month wrap around to the. x t e ab s a s e e r so t n e e R a e 3 & & a e 8 a & 2 R a a 2 s h a n e a . He . R e 8 8 o a 2 ? af a. no a e cs 2 ° s a: aes c e a e e e G e e g coe a a g B a n s & R ae & ot 2 a inti La i e iene a o e an e g a a n e 8 a 3% w a e 2 erat a e 2 2 5 g a z e & 8 a n i e 3 e a e Rg s 8 c e n % a ¥ * e e : 5 g a z e 2 R 2 b e t s s a 8 n a e < 8 o e = : a e s = mh g ae a R E S 2 c e 3 2 x R e g g g a - 3 0 ¢ a g © . g = 8 g a n 7 o d a a t 8 g & g R e T a . s a 2 a i n a e & = < . r i . 2 B 5 8 8 8 + ai s e . = 5 3 z 2 8 8 2 a es mi 7; & s a g s 8 s a a 2 8 oe & a s < = R e s g a g 3 o a . a 3 ue a n e has 2 j a e s a e a ae a aa e o s e e n g a 8 s a 3% x 2 @ x = “ a s F a Z a , 8 mu a oS cass moh s a a n = ee ; a z a s 8 Ls 2 ° i e 4 ° = d a o n o e ee 28 “8 z a 2 = a 5 ° = a 8 a aS — c h a n 8 s i na e a o e 2 a pee S e a s t e s a a t e a b r : = a a . T e l e a 8 8 a a a P a = 2. an a 5 i o s e s a n o s : a. =. 2 as aes a t 2 a z a n e te ae oa g e t e a k a c e o e M o d a l a ) s e aot ne 8 & 8 a s ° R a e s & p e & 8 e n a g 3 2 ° ae - a o a o t k g eg 8 8 a " a n ~ pee oe é 5 ae 8 8 e r a 2 a a c a ae n a e ee % ef a a Wsa2 7% S 8 © a t a seas 7 g e te a 2 g e e g s 5 o i . a a e —) ees c o t e # 8 a e 2 © a Eefe x a n a a 8 3 g g a ? we a e @ s a s " g a s Rg i z o a e e . t e e 7 oe a e a 8 a a a j t t s p e e 5 5 z o n e a a . ee ee o s 8 — P a n s “ g a a 8 R e mean 8 & 3 8 2 : o t } 3 a x ae e 2 g & = ~ a = & 8 e a . a t e a 0 a . g e e g — c n a a t i o t § g 8 g e ee a g i. & B oon ¥ g 8 . ‘ 8 5 a s R a a c o e a e , & 8 cast g si = 8 g m o e B a n e ” 2 a A & a F a c e a g & 2 3 = nee + 2 & L 8 . a t a a n = aa a S a s h z e t e wets oe nee: a i 3 5 8 e e n s =. c a n e s e e e 3 z r ace er yeti a e 2 = ry 58 2 . ; oo 8 x ten as o n z e ol e rein cra . ce e o s r e a c o t c e = sitie s g & 8 c a n s a 8 e. = 7 & a =” 2 z 5 a2 < 7 r a e 8 8 a c e 8 e c a e s 2 7 8 ° ae 8 5 ~ 2 n e e S e o n a 2 9 e sends ai reat g e see $ e a v e g g e k t e s = v i n n : pbs p e ° a a e 8 3 & ~ a n a 2 ¢ a z 8 x ¥ g R e e 8 - g 8 2. x ° s a t e i ° a e 8 % & B 8 g Bans s rc e + ie a n e . 8 c e a r e R E . a a n ‘ " " ne: g % s Th ¢ R ae a 5 . t a e 2 s 6 g a o r 2 e s & B e s ee gpee- e c o 2 a R - < a , be t B r a e . & 2 a z * “ a a g 9 & a a , o © a B a s o i e a 8 2 P e t s = grt a e = 3 o n a a 3 oBaas B e z < < 6 oo wi 1 a 3 = 528 Baar o . ~ aes ae a n e <8 of * ee Ne a l a & nt a 7 g u e e e : Ee a e 2 a y e s a v a t e rs a a s s e 8 s ° pase ® e a $ $ a k i ts a. a ENE a a e = 2 8 sore & 3 8 c a s k : 2 aR g e at e n o t e ae va n e s om == 2 e a r n s sont i . n a e . g 8 a o gas’ - nn oe v ee o e a n e s e . a . 2 ° 2 8 : a8 b a n s = 9 7 a 8 aes a o n e s c c h t h a a SS = ae = = oe x = 4 © g 8 S it eae gz 8 e e o e a g 3 a — ree 3 @ “ e a e a s t a n c e = “ 2 g es mi 2 The above data are the ave 7a, Be daily flows fo r the given wate! r year. + The ena are numbe red in the far seft col u m n Je my is 1 » Fe eb Mary is 2 a .) and the flows average day aes fort month me aro und to the ee a gee ape 25 Re une Danse 22 En gnencce & a2fn RAS nae e ka Seaseke z°° 2 23% eat & z ZN e "fen each Sseaace g2zsarsgs SeRo “8 288 8 Be ace arkaerey 58 Bs g Sc. ae hg SRR" eS Res ae 8 gfe ngsesey Re AeeRense Bataatagtaccy ate gh 58 ninag?e te 226 Rs Feand gare lapsess nae eae zaaRane SarancarescSetea Cages 58 8 ate 22% Benak ne Tete wae Aca 2 82 Bak sfmog ets Ra agsaage gato ageca% g s : Bescenate anes a anekeagee 279,75 eSgent feet ee8h Bere agatan ees SR xaeRAoA oneneaceeeertencenertas sgecaistecnasafeseanaat ats % meee eee t a n tees aa Riclenca = gas gas” ee aace B®SSRaae Onn nee s a s eine ao —ahene®c4 ass . wyaato a gazak i558 Baye "* ed weeeRcehes aeanet ea Fests Sethu al ose an cen cass alestiaescssteagegengts ages pareteaany asda ak Seat eetc peatcexercas gence lasnssistesledaetes sfeassitgagnzatesusnaed! = art fees 2 3 = Saha ens a aeekee get etpcolacasslsseeatrezen e287 Jstnagnastanedence! Sorters eae tert bevansscacncetadteisedea meager eek eales, ceatheus® 22 nes 2a8ea fa25 et" RS F R T IETS wR Aas2age Sie Rewfa Basan mentee nenh ne ABA en egtas = _ttheosasnRnnsaghustyayis Ree erent vBar Rae TC nrneaened co ales Le hersrRs #2 as efhswont ge Baiagsta rer assed sonedtacuconusnenaeedes (sce tnercegnasegsnzne et Sear pe catamaran ao MQoseRagee gesesennsenreabars Ragraas Ra koe anosagseeastnars Sean leat SSRRISAB guseze heslQo8engsa Zs aRe RepeResaks & Sertelyuworesr = zesVngask aeee eee eee ge hegreegogeeaRee ZTaARNQE % Be. 5 ae8 RGogt o % 2 Be gateak, oe _—_ aSake BR 23netenk. ° eseataatag?* on’ a2 oe . g = R%e 2 8 goneGecetsfics ceetr = aa eg Ren see ann os BR, g 38x be pop Fa a ale aR gg 2722s aap eaeey age BR afin? wee gees = Breen. s_a F858 arte Re wok 852" aR? asag® a g eaeec? 8 = 8 2 aetszasnr, epekengca’® eto gee aud = Sey ee aRakage tar ohare ar eanes EER 8 Skane oagihe sess go eee. emia rate tke ake = aR" aRhatarng aagea®= 28—s 282° Ssgaks penta RBsgracas wg stake ara ere eet ig at oeett atti kee seurren?)oe28! re eee eee RAtaraccaarsgatatsecaeso 2 . s Sana ee ars - poe teat, ahea’ ans. ote Reet sene yaa, Sxae evesaelas8a8jazagee cece anho" Greaan’? alae ans, ias waRQR vesetan® Case ro rwonalaaget eagle 1st -eees = geavnens?® aBnd 83.785 anne se atan® eetelocntnssesnaty rine?! eivaacasenmones Reqecanso8 BERS oF Baas Skuwie asians R52 tavern gataomagcedne’? B8qgraae Lo _zoolKSSFE S%e9_ 928 a5 g*sa8 S27 ep gat =p Fsks =2bNs nase . Watt ag HoRERRAR 8 speel°7e"”? ao sans os 88 Negro ZoowoMNBRAhads #tel.sa% aeSesnaad nae.” ae, ao eae8a geese Sdeaceszae a AG aKea ok cog oenegetain RaBRQ SZRRRE BRAAES ZERRTERERAOne eRRNeLhR a at RrnSaRkRS e8 @Ekia.- A, AeA SRRARZ Bataan sin neasQReNngns NQRAKanelkS gRae8acq Monmeth® 8 ana aaeeerala Gael EEL gzaqadens ennontaagreeeza gnaaz a ef hGaggssak sane ae ere ann kane gegeshs vale gemesconiencesnagtonnars A V R guecs eee eee ee _gedtecsocencs SaanENE EEE a gs 3gnre xagseces fk el fea emailed baba ba ere Naso )8|% eae 3 The above data are the avera; ge daily flows for the gi given water year. The months are a numbered in the far left column (January is 1 , February is 2, etc.) and the flows for each day within that month wrap around to the following line. 73 125 Sb 3 46 39 4B 49 SS 73 SI 5S 35 OW DB WwW 31 B 18 18 14 14 13 4% 2 17 15 30 139 101 64 84 47 32 46 4 33 25 2 2 18 1S 14 3 S$ S$ S$ 6 12 15 15 8887776666 6 6 SssssS 31098776666 6 5 413 13 11 11 10 100 8 8 8 8 8 8 33 19 14 17 46 121 94 67 8 4 35 41 36 170 101 100 azanuweis 413 12uU Ut 6sSsSSsSssssswmuwss 9 p93 58) 3999's 9 _9.- 9-9-3 _ 399 10 49 39 33 66 61 S7 173 93 198 436 175 184 154 7 72 140 63 89 130 103 167 56 42 8&5 9 AMmMenoawwenes 3 7 9 7 SI 7 “° 954 a 8 45 S 149 462 210 147 231 186 292 174 64 32 21 17 15S 13 I 11 10 10 9 9 9 9 12 15 15 13 17 15 6 12 13 11 12 109 9 9 9 9 9 10 12 9s8 89877777766 6 6 1 3 10 10 12 12 11 100 9 12:12 D7 13 13 00% 2221S 71IBIBSNNRMIWNMB”A RM 4%*37 2B 2D 19 21 WD 19 18 17 16 IS 14 BRHwWW9BSBETFTTFIT7FTECTU D MBIDMDBRAES HSL HB BTU 19 1 i 2 a gfe akegn aha 2 F2 2 5 ake estes 8%_ | gk BRR BARD a2g ee aknate st yhgaBS" copakGgnezeeRe BE ED a SRL RRAGARERS argh aSentg ghgh@ar ka" so cnSRQMnt FRR BESeo cm, aN NORRAHATR aaghgratanke nfig tar PRT grog snbeaan san SEB er eng hg RRFARAAMS a2geiatgane efaka SB ano taaBg RRS CARR gk a pon Te Ry PRERAKARES aagegtasazae eta en 82 srokeaszane gaan Seren ag kgTNVORARAD, eageakahanss anak a Sa gn aBREAREQARK Fe pa h ga RRRERANT Ze a2gsqtaens8e =eeky Fagn* sERRKS_ RRR ae ee Rg tA MAMAARAE So atgeeRRaang? sxehe BRoga se GgsRA RA FRA ok” HV ye anteaRasae 2a2gareeesses state. f%ega sekaaan aan OSA se een Ba TILGRARERS 22gReSFRIsRs ofaRar Pega Bes QsNehone Shara, goon sVFRaAges a2gRRaSRZlRa atekn@oSPaoa a SRBRRAMATRK SFB A TL oyrBaVerVasaass A2ZRSSRRALRA AETAL BPs Rea GARERLABKK AALLSLemngeVa*RSGAIRAHS 2ASRSRHAALRS SRAASLSE Fr wo RaaKRFRRALAAKK HIRAO Au meaesaleNRRRRAGA 2AZSsVFRaAreNA Bake tatekzmogarkaSeeRsagan RHR Ak ahrnewsiskeagraanane RMORORSRALHN “ARAMA LvrwcarRoPoRSersAeR “ASsaqrRravnworr se geHeRaas & 8 & eS gente ged cenka = a®SigeSRF ght es ok RyhgthhHs Soatgraensa® seB Sarna T8taakPoawdaes 32 9 ot womans pares Rea ta? azaaea ane ®nsaka Pakage tie kata Bette ka ofSNeg Gg kAt¥e tag ta Samaash Set Para east Rhag Mi ggMaln FBR vac ensenap a AaaAs SagteFaanaah® oF _hagee MWe gTBiggkerR ERRH eel emorkags SRRARD seg @e%eenaak Bete gt agen AReg tsi cg kere Behr Toa Maka A VARS eag8eg%auxaad Bea aka ges hag tar g geste BE gr erg Oem ag ele RARE “sy8eFannane FoRkitgxan sag halggaahs BE gr rer sree gz pees eBs Cngtgizansee ~at%ehgagc "Seq heen R82 BRST een te Backes Tae engine anes wghtasagen, eee k ater g nea Bee ace eee kadeages wretshaReae a Sdaason, gas eeaxee & BE Sme Beene t thle rae es eeeSeSeranss oF VSakssys, sae F MF eeghsh Sener mgwnat MN rR RRS SEnReRTBARer ok oreRetataansstaezgesZS eR nasnadwenalt sar etganaa RBSSSCREARSE RA EnReMVgswoR AMV HRAKSVFAR genrsnanmenar RAs ARGAeR eRERGRRRRALS BoSasasergreanstsRglensAse YotrsnewwarwnaaghgssaRace PSOLORSBGHRAN “AHR Svar searMesaGSRaBIe -ReQrerrngeerleHfoRSRaes 18 199 238 239 113 D 3 2 14 B 1 an 4 4 12 12 11 33 ST 41 76 S2 The above data are the average daily flows for the given water year. The months are numbered in the far left column (January is 1, February is 2, etc.) and the flows for each day within that month wrap around to the following line. ah s oRe wena wegen ear cece aah es 2 ont bnraes wasentgtees Soe es is 2 72 “ a wo e t =e = ee a e ? x ean a n aa — gee e e Si ccce <eeeee ak? ae” ns a t e s _ wnnatEsa a n e onrees . 5 ao an wwe ebeean oes caeead ate gk Phar ean aan g e t s e e a r ” ? catne 7 al. x peltiaccoas “geeney B e s ” a t arente ae a a a ” eee Renna, 8 Se = ac. Sa ae ae ogi ae ae 3s a" = = - 8 EE ects aiiaes ren7" oF 5 B S x 8 sao a “28 eS R a annnatss ake. 08% _ s Re 22 RE gz a a 33 3 & 8 oe 2 2% go ae zee B+ wee gree e a ants as 2? ° o %8 oe ee as = ae an eine gs g Bo a aos = x22 Be” a 2 e 5 a s 8 B o "eee g a g a 3 a k 2& 8 5 % a ant & “ ang o e « var a e 3 8 g g z 5 “ 8 a&s eee g # 2 g s a e o s = z 8 n F a s 2 8 a ® o 7 aoa a z v a s asb® 2 7 on w m L o a n 2 ge a ena © “ Z z © & 3® 8 R 5 a = 8 a a a ? a s a e t nnn sees 2 & pete a5. o n arenes: # 8 2 8 Re e od 2 8 Seu BE evens ene Rx cinaanate aaaa 8 aoe 3 vane as” $ a e n e 2 + 8 odes & & a s & 28ae rere arty 3 8 xa. Roe. a n ag “ e g a e a b a a R s ao” gone 2 8 g t e e a sean le e*” e s oe e f g 8 g ght ae = = a 2 8 a — 7 b s a* ac R es Se on78Te 2g fs 2e8 S ge a an = a*°? a e ? x8 Xo B& 3 g gks 8 28 bo 28 P y “ mena e e a t . 9 ? ® z e eae gee a0 7 8 o n e x % prEEaS) zace “ a © Ra Be & ge ag 3 eBs = at Seuss gz 7 ecu Sas 29 g | a a. nich cache beralee 5 a =aae Eanes reeonens ag ve v i z e aaa as * g=%8 7- ous”? a2 se £8 5” “ a] lace 28 ge ean = & g tx 2a 85 8 x a “ “ 2 8 a 2 8 8 8 x . “ 8 a 8 3 3 8 2 B=" w- e e g a eg = as -8 R =8 8¢ e a8 a 3s” “ a RR eh ag 8 gs ened Sa ae 2 4 8 we te aa bas wa wrBee 2s ge 2° gauce i : av ear = Ry a gs 2 “ “ 2 Ra Re et 8 s “ w s a i “ e w 23 88 ges Ba 28 ” wa e r tee8y @ x° = arsine e a o £28 &g e aga ex.°* w a a 0 2 h e h e k a k a 78 3 2 6.8 g s e e s i e z a a qs “ a o Wie © g 2F a ceo” ae a & & 6 a tv Rg g Stuns e h o e 288 + e v R a 8 me ars v o m ice R e a e % & % s a e 8 gaa we ae ar wom g 2 e R g eet 38 8 oe Re gene ie a g 2 k cae 2 L e Roa skets g e a g e e e ~ge “ a e a e a z S 3 8 * a 8 Roses % s 8 7 28s z a o “ a co & gs a 2” g Se = 3 a x0 ae ae aoe Re betes a. a © aes ae #8 QR & “ae &s “ . « 28 aR .32 Re. a 28 aes be 8 8 = g eauad a s 3 2 a # 2 a a el an? 8 a e a g g eae 7 8 “ 7 Be g 8 g 2 & 8 a r % g g 2 a 8 n e +e 2 & 0 8% ge = 6 woe as eB 8 e ae Bak. a = e 8 gs 8 e, er a 2 A 3F g r y a g 2? = = g ag o e # 8 g 2 a ® & i o n g e e a & . eet.- cease rat ee eee iets 6s _ See nests one aEenes? aa8 92k n o a g s ie ao802 geben i s gRke 2 4 “ 8 2 8 a sae g age pacts hee oe Re Ru wf naa 88 a 8 ek eg “2 s aa® Rane = g e 222 2 & 3 a s n e 8 3 8 g s enk. sc 8 g o g e “ 8 oh 2 8 g s 8 B s wel o @ “ga oaR8 8 8 3% g ga 2 * ¥ ~ a afen=S e e a r g x eee a e r e ? ressaeas x s o e a eae e s 8 8 SEES & g 5 e s z e zak B R 8 age” ¥ ° ° z3F N e whe seated RRR x8 & gs afl. 2 ° oer Qa = a° B ea . x “ as? a os g o agers g a 8 to n®en e % s ania: ge 3 8 ER * = a d 7% ues “8 g R B a k rs e.2 8 2 % g 3a se 88 a § . 278 ea 8 ao es ® aR "8 a® ee a a&s eae, a gee ee g oe a aon ayo Rs a3 a® n¥ aa at gt ga 2808.0 a a E g ° go az oa. zetaagat e e o 8 . 8 sea R ga® s e 3 seeds g . s e as & = & av& ae ee Se g e a r a e 0 8 & 5 R e w e a s % eg ebro The ran data are the avel TO: ige dail flows for the given water year. The months are numbe r e d in the for left colum n Ganuary is i , Febi ruary is 2 » ete. .) and the. flows fo 1 eac h day within ae month wrap ‘aed to the MO 2 33 4 7 6 1 77 i 2 4 1985 1 105 $4 S52 125 75 132 2S 99 84 198 231 39 25 15 302 2 8 erate Berne BRage Fen B28 e ¢ a8 ace. Fe agen8 cPaG BR ge 888K = BStee wae vefese8Rsns. la gkeate Se Rakse gee iren BPR sanogy TST HFRRRLA ALG BeGegen "2a Ragkagt F8K e"Regerey “S°RRARR ESS acg gbatgra rte Agaiaes Tare MDa TE CaS eSER AAS cs B2 pe RS. KRegkaygsNrarsag SS teg eo. om MURS gh ararewse a2 g°e RS. 8e gt Sc - SRarg ny Me PnVtegaataRes ahtegr ret oo apegtansees a Pe =.9%en g aay te «a BAate HR LWoaeseFagsRaR2s aFSnqrh™o oN aagagskearaas Aegean g Seeesakg seas Bea MAB Ra RASA Baste eg Saagende Shae le REM ae cola TRE RRSRRANER Roeat ele FINA eARS SRRRNZ ZRF nal eo _ gVVeVGRRAHRRas RRagc nn BeahneFy Aseghs PRET Ccar maa tM RASMAFELKG BR aS emen BARA AAs LsRASAR TSEHLPnunemoatlSRAIARArgy BRR gpemrloQgRoSFRARTIRES ERG RRauamBamahtsRSSRReerng BARTYrreeSn ego gGSRRTVRES BRAK covranvaaHsgagsseeaier AFeQavenvKovreosaVezgrgAy “AR gmaven romrsoegageRgaaare —< 2 = & x = e ~ BF alg 28% Se 5 az oan hers 28 “P2820 Ra =82e% aw ®Sectaagig wen RER S28 aR SBS Mee Eee ans” Ae RBar en, Re. okey oAa yg Fay BHATT: we okSR a7 pe RPeSSyigre Baer mek RT eT RRB pera Sa Rese eta eke sl eens Re ere eneteee"s 2@h38g igs eter bee Re ag Reg onay Teeter eT ret ee coe = as ee 3 at emg MB Ge" SoS gBka aed parton tT 8S oag Soh egea, SgeP RRR eet agsoe exaRRe 2 z g 2 Rhea CHESS | ake REAR HOR wee ek sats eaaasy Rye he kG2 get a kas eaxass a2 gr etl Re eR esee lars Bee eg AAS RAR SS oRRR, Byrnes ee Rose l seRes, a oo aeons a a 13 “2 azeate e = gre Gh Reow oak arsg nee PR mnt on tg genes. eas, meat, OES Zh aeES, akg Ri FooonseRess RTH SRT BY Ue gaRagihggesy, Beret ar aa Cages Keane, muBgo tt atsrenaagesa ear BR eo RF anak heen, gaa® ashe aeaa8 bear” a8 - 8 x Bc Rae RErorRaRssRasey gh no Bat Kea g Ke RESRRLS BRAT oResaa) names Segre” me RaoFFoBRIOLERRRHSISKBY LR eB oA Ae gaBsRlaaea, KB oes ea lorgncSegaaa® waRanSSoReValQeSRHRRsZR RFoOMi Re HH BSogVN ERP aRan, SAS HRA M ie waeeaeseeasad masa eg BORRRALRAEBRRGAMZ BARAK eM BOEVaaVSEBLGRRUn TERK RLaMun ade RNR gases Ramaeak a BSegRe lr RAgGRESRlR Basok-ee leo Kine LEHRSRISTGH garrison Re Foxoveneageaynags Qannee Sr Voy VoRasVzaHI™s “agagqnerQuneserseRoBIHaR se “aKanmergugern Rega Zesaass oe g & g 6 The above data are the average daily flows for the given water year. The months are numbered in the far left column (January is 1, February is 2, etc.) and the flows for each day within that month wrap around to the following line. U.S. Army Corps of Engineers Hydrology Information APPENDIX A HYDROLOGY Table of Contents GENERAL Basin Description Streamf lows CLIMATE Temperature Precipitation Snow Wind Storms Ice and Frost Snows lides STREAMFLOW RECORDS Extension of Streamflow Record Sedimentation and Water Quality Evapotranspiration FLOOD CHARACTERISTICS Snowmelt Floods Rain Floods Past Floods Probable Maximum Flood Area Capacity Low Flow Frequency Tables A-1 Monthly Streamflow Distribution as Percent of Annual A-2 Stream Gaging Stations A-3 Mahoney Creek Correlation with Fish Creek A-4 Average Monthly Precipitation and Runoff, Mahoney Lakes Basin : A-5 Percentage of Total Monthly Runoff Attributable ; to Upper and Lower Basins A-6 Evaporation Losses A-7 Maximum Instantaneous Recorded Discharges A-8 Annuai Maximum Instantaneous Recorded Discharges at Mahoney Creek A-9 Mahoney Creek: Flood Frequency A-] ] Rainfall Distribution of the Probable Maximum Storm Res ree eee rrr uv oa oO i o-6 fe ot ee colon es =S5605 4 eal eed ed oak, pedo SPErrrSrr SPry TO Noo fears artes nNuOoowow ' ' LF —t at ot ™N nmr —O”o >> eae > rrr, ' NPM Nn — Fm > >YrY ' > wn P>rYp Seater —-—-o OnNDMN A-12 A-13 NOOLD rPrrr 1 Figures Ketchikan Area Percentage of basin area below an elevation Climatological data for the City of Ketchikan and the Beaver Falls power plant -- Precipitation vs. elevation relationship between Juneau (sea level) and Mt. Juneau (3,400 feet) with Mahoney basin's elevations superimposed Drainage area elevation vs. unit runoff Gaged and synthesized streamflow at Mahoney Creek Correlation analysis -- Mahoney Creek vs. Fish Creek Monthly Distribution of annual flow from Upper Mahoney and Mahoney Lakes Peak. discharge -frequency at Mahoney Creek Summary hydrograph of. the Mahoney Lakes basin Probable maximum flood hydrograph for the Upper . Mahoney basin Inf low and outflow. hydrographs for the standard ‘project flood ; j Relationship of peak discharge and pool surcharge to spillway width for a normal maximum pool elevation of 1,980 feet Storage vs. discharge for weirs on Upper Mahoney Lake Area capacity curve for Upper Mahoney Lake reservoir Upper Mahoney Lake j Low flow frequency curve for the Mahoney Lakes basin A-ii > Seine Dwr ' N APPENDIX A HYDROLOGY GENERAL Basin Description The project area lies within the region of maritime’ influence of southeastern Alaska and is in the path of. most cyclonic storms that cross the Gulf of Alaska. Consequently, the area receives’ little sunshine, generally moderate temperatures, and abundant precipitation. -The rugged terrain exerts a fundamental influence upon local temperatures and the distribution of precipitation, creating considerable variations in both weather elements within relatively short distances. ‘The area is subject to frequent winter storms of varied precipitation intensities, with rare occurrences. of -hail and thunderstorms. .The Mahoney Lakes project area is shown on the location-map of Figure.A-1. i V4 | \) : The Mahoney Lakes drainage basin is located approximately 6 air miles northeast of Ketchikan and 5 miles north of the Beaver Falls powerhouse on George Inlet. The Upper Mahoney basin varies in elevation from 1,950 to 3,350 feet above mean sea level (MSL) with an average elevation of 2,350 feet above MSL (Figure A-2). The Upper Mahoney basin is the watershed area above the: outlet of the upper lake. This watershed is 2.1 square miles. The Upper Mahoney Creek basin is the watershed below the outlet of the upper lake, but above the inlet to the lower lake. Runoff. from this 0.5-square-mile watershed enters the creek channel and delta directiy and then flows into Mahoney Lake. Average Upper Mahoney Creek-basin elevation is 1,350 féet above MSL. (In some publications Upper Mahoney Creek ‘may be referred to as Falis.Creek.) The Mahoney Lake drainage basin, above the lower creek inlet, is 3.1 square miles. The entire Mahoney Lakes drainage basin is 5.7 square miles with an average elevation of 1,130 feet above MSL. The nearest climatological station with the. most similar meteorological conditions to those of the project area is located at the Beaver Falls (Figure A-1) power plant east of Ketchikan. Much is known about the Beaver Falls basin, so that this basin is often used in comparison with the lesser known Mahoney Lakes basin. The Beaver Falls basin shares a common divide with Mahoney basin and appears: to contain similar topography, geologic features, and exposure. However, the higher elevation of the Upper Mahoney basin would indicate that.the climate in.that area would havé higher total Precipitation, less temperature extremes, and higher total snowfall than the Beaver Falls basin. No permanent snowpack exists in the drainage areas, although considerable snow is received during the winter months. Although the climatic data from Beaver Falls are fairly representative of sea level conditions near the project area, lower temperatures and greater precipitation amounts will occur over the higher Upper Mahoney basin. “KETCHIKAN LAKE € Z x SILVIS Lake: (BEAVER FALLS ETCHIKAN A CLIMATOLOGICAL STATION @ GAGING STATION é RIVERS AND HARBORS IN ALASKA 2 SOUTHEAST HYDROELECTRIC POWER INTERIM SCALE iN MILES Elevation in feet MSL w So S 2. Tit it Upper Mahoney Ler — Shimane — Heufias = Upper Silvis sears Msi pet eches Pde pense T Rea ereer abt 1000 ‘Upper Mahoney Creek 54 0 10 20 ~~ «30 40 50. 60 70 80 90 100 Percentage of basin area below elevation Figure A-2. Percentage of basin area below an elevation A-3 Streamf lows Runoff characteristics of streams in southeastern Alaska.are representative of the maritime influence. This influence greatly increases the runoff per square mile and also changes the timing of high flood flows from those experienced in central or interior Alaska. While flood peaks occur in May - and June due to snowmelt runoff, the yearly maximum peaks generally center around October.» Normally,. about 75 percent of the annual. runoff occurs during the 7-montk period from May through November. -Within. the study basins there is very little soil over the underlying.rock; hence, the facilities for ground water storage are. exceedingly limited and the. major components. of runoff are mainly surface flow coupled with some subsurface. or interflow.. Therefore, short dry spells. have the effect of generating extremely low streamflow. Streamflow. distributions for the period of : record at-five stream gaging stations in the area are given below. Table A-1 Monthly Streamf low Distribution as Percent of Annual Grace Fish Beaver . Mahoney : » Creek Creek Falls Creek Month | (%) (%) (%) (%) Oct 14.1. 14.2 13.6. 13.9 Nov 10.4 11.4 11.6 10.5 Dec Vee 7.9 729) 6.7 Jan 6.2 6.7 555 4.9 Feb 4.7 5.4 4.9. 4.0 Mar - 4.7 4.9 4.6 3.6 Apr 6.5 6.8 5.9 See May azae 10.4 12.0 11.0 Jun 10.9 10.0 11.4 1233 Jul 7.9 won 8.1 10.4 Aug Hae 6.8 6.0 8.5 Sep 735 8.4 8.5 9.0 Total 100.0. 100.0 100.0 100.0 CLIMATE Temperature Temperature records are not available for the Upper Mahoney basin or tne Mahoney Lake basin; however, records maintained at Beaver Falls may be considered representative of those encountered at the lower elevations of the Mahoney Lake basin. Temperature variations, both daily and seasonal, are usually confined to relatively narrow limits as a result of the dominant maritime influences. Although variations between maximum and minimum temperatures may vary as much as 40°F during clear periods, the differences between normal daily maximum and normal daily minimum A-4 temperatures range from as little as 9°F in December to around 16°F in June. Seasonal variations range from a monthly normal temperature of 35°F in January to 58°F in July for the Mahoney Lake basin. Extremes of record cover a range from the maximum 88°F in June to the minimum of 1°F in January. Extreme maximum readings above 80°F have occurred in May through August. .Low temperature extremes of around O°F have occurred in both January and December. During periods of calm or light winds, local temperature variations are frequently very pronounced. Variations in local radiation and air drainage produce wide differences in temperatures, ‘Particularly between upland or sloping areas and the fiat, low terrain, which is greatly affected by air drainage from high elevations. Precipitation -Records of actual precipitation measurements at the proposed site are non- existent. The 5.7-square-mile drainage basin above the discharge gage located ‘on Mahoney Creek produces an average annual flow of 104 cubic feet per second (cfs).. Not considering infiltration, evapotranspiration, or interception, this average annual runoff equates to an average annual precipitation over the entire basin of at least 248 inches. Rainfail records for Beaver Falls indicate an average annual precipitation of 149 inches for the period of record. The Beaver Falls gage is located in the same area, but near sea level. The high elevation of the Mahoney Lakes basin and orographic effects have a marked influence on the precipitation in that local area. Also, because the 248 inches per year represents an average condition, it is apparent that the Upper Mahoney basin receives considerably greater amounts of precipitation. For instance, if the. lower Mahoney basin is assumed to receive the 149 inches characteristic of Beaver Falis, the 2.1-square-mile area of the Upper Mahoney basin would have to- receive precipitation amounts in excess of 450 inches per year. Obviously this is a gross approximation; however, the implications are valid. June through August marks the period of lightest precipitation, with monthly averages at the Beaver Falls station ranging from about 2 to 11 inches. After August, monthly amounts increase until a peak of 32 inches is reached in October. Monthly averages then tend to decline from November to July. The heaviest storm precipitation amounts in the southern coastal areas are the result of fall and winter storms. A summary of climatological data from Beaver Falls is given in Figure A-3. “Mountain versus Sea Level Rainfall Measurements During Storms at Juneau, Alaska," by Murphy and Schamach, (1965 Western Snow Conference) a precipitation variation with elevation study, specifically shows the elevation precipitation relationship between Junéau (sea level) and Mt. Juneau (3,400 feet) (Figure A-4). Although this study was in the Juneau area, the relationship is believed to approximate the relationship between the Beaver Falls precipitation gage and precipitation in the Upper Mahoney basin. Figure A-4 indicates that a basin with an average elevation of 2,350 feet (Upper Mahoney) would have 2.3 times the precipitation experienced at sea level (Beaver Falls) and a basin with an average elevation of 1,350 feet (Upper Mahoney Creek) would have 1.75 times that of Beaver Falls. Based on™ this factor and the average annual precipitation of 149.3 inches at Beaver Falls, it would be. apparent that 343 inches of average annual precipitation A-5 9-¥ STATION Beaver Falls Ketchikan Beaver Falls Ketchikan STATION Beaver Falls Ketchikan Figure A-3. CLIMATOLOGICAL DATA MEAN MONTHLY PRECIPITATION - INCHES JAN FEB MAR APR MAY JUN JUL AUG SEP. OCT NOV DEC ANNUAL £3)56'3) 25 6) O71 829) 7152) 7 Ol 7) Pn5).9S 9.93 15.88 23.17 MMSoV/TAN aN aT AGt! 15.06 12.74 12.15 12.88 \38.62 7/20 8.48 miley 15.29. 24.77 17.63 16.18. 162.3 | MEAN MONTHLY TEMPERATURE -~ F * | 32.5 35.1, 37.8 41.9 fp.6 57.0-59.4 $9.2 |54.2~.-41,0 -37.8. 33.7 ° 45.4 35.1 36.2 38.7 43.6 50.1 55.2 58.2 58.9 54.6 -47,3 40.9: 36.7 46.3 SUMMARY OF CLIMATOLOGICAL RECORDS ; ; Average - : Ground Temperature (Degrees F.) Annual. *. Average Eleva- Years Precipi- Annual tion of ‘Maxi- Mini-. Mean Mean . Mean’ tation’ Snowfall (Feet) Record _mum_ -mum~ January July Annual (Inches) (Inches) 35 24 88 1 35.0 Bera 4514 pA ai Sv a3 90 64 96 / 8 35.1 58.2 46.3 162.3 32.9 Climatological data for the City of Ketchikan and the Beaver Falls power plant 4.0 rm Oo Elevation ( 1000 feet ) 1.0: 0 w Oo Average Elevation Upper Mahoney Basin T T Pbaletetupates r Tj Average Elevation Lower Mahoney Basin — phat : T . 1.5 2.0 2.5 3.0 3.5 4.0 Ratio of 24-hour precipitation at sea level to precipitation at higher elevations Figure A-4. Precipitation vs. elevation relationship between Juneau (sea level) and Mt. Juneau (3,400 feet) with Mahoney basin‘s elevations: superimposed h-7 fall-on the Upper Mahoney. basin and 261 inches on the Upper Mahoney Creek basin. In compiling the elevation runoff relationship (Figure A-5), gaged streams in two different locations (southern and east side of Revillagigedo Island) were analyzed to determine unit runoff as a function of basin mean elevation. As shown, the basin on the east side of Revillagigedo Island (Lake Grace) had less unit runoff per square mile than the basins near Upper Mahoney on the southern. tip of the island. If a line through the average elevations of the.gaged basins. on. the southern tip of Revillagigedo Island is extended beyond the three known points out to-the average elevation of Upper Mahoney. (2,350 feet), an average unit runoff: of 16,300 acre-feet per square-mile per year (48 cfs/year or 310 inches/year) | is apparent. The difference of 33 inches between the average runoff and average precipiation could’be attributed to evapotranspiration. Conservatively, then, -it can be assumed that while the Upper Mahoney basin represents an area only 36 percent of the entire Mahoney Lakes basin, 43.8 percent of the average annual runoff comes.from the upper basin. This results in an average annual-runoff of 48-cfs for the upper basin. . Applying the same procedures to the Upper Mahoney Creek basin, an average unit runoff of 11,450 acre-feet per square mile per year (8 cfs/year or 215 inches/year) is derived. An analysis of 3 years of comparable streamflow data (October 1977 - September 1980) for the Mahoney Lakes basins indicates that original assumptions concerning the.precipitation/flow relationship between the two are essentially correct. The observed mean annual discharge for the snort period of record at the Upper Mahoney Lake outiet is 40 cfs (estimated at 48 cfs when no data were available) and, at the lower lake for the same period, 83 cfs. Although the observed discharges are lower than estimated, the upper basin contributes 43 percent of the discharge for the entire basin as predicted. - The lower flows can be attributed to the fact that for 2 of the 3 years of record, the annual precipitation recorded at Beaver Falls was 23 inches lower than the 23-year average of 149 inches/year. For the other year it exceeded the average by only 14 inches. Snow Snowfall records are not available in the immediate vicinity of the study area; however, snowfall characteristics for the area can be described through a study. of the Beaver Falls records.- A trace of snow falls as early as October at Beaver Falls, although the first snowfall usually occurs in the latter part of October. On the average, there is very little accumulation on the ground at low levels until the last of November, although at higher levels and particularly on mountain tops, a cover is usually established in early October. Snow accumulation usually reaches its greatest depth during the first of March. November, December, January, and February have the heaviest snowfall, although individual storms may produce heavy falls as late as the first half of May. Snow cover is usually gone before the middle of May, except at higher elevations. During some winters, when temperatures are above normal, there is a great deal of thawing, which causes slush tnat later freezes. There are occasional intervals of rain tnat freeze into glare ice on contact with the ground or structures. A-8 6-V 3,500 Legend © Beaver Falls Creek A Ketchikan Creek %& Mahoney Creek a 3,000] | Falls Creek . OO Grace Creek i NN Psairl l ; I * Ella Creek _i. 2. Weighted mean elevation for a 8 Manzanata Creek TTL Upper Mahoney Creek basin | .- “2 S 2,500 Fish Creek cnet seed Unit runoff = 11, mi acre feet/mi’ ye > vo ‘v 3 2,000 S o vo Dn 2 “5 1,500 “4 won ane cry Rape fam = : 5 Southern Tip Revillagigedo Island [ jane eee Hepes ee nae LL co al = 1,000 : 2 aa iL omer bra Beis Peralta rae - Weighted mean elevation i g laiaaaia Ser aad aay “| above Upper Mahoney Lake “ TSH Unit runoff = 16,300 acre feet/mi2/yr_ Bell 500 0 7,000 8,000 9,000 10,000 11,000 12,000 13,00 14,000 15,000 16,000 17,000 Unit runoff, acre feet/mi‘/yr ! Figure A-5. Drainage area elevation vs. unit runoff Wind Wind records are available from the National Weather Service Station .at Ketchikan. Observations indicate that the highest winds occur from September through March. In the Ketchikan area, the high winds (greater than 50 knots) ordinarily blow from the southeast up Tongass Narrows. These winds are caused by the shoreward movement of maritime air. Speeds of 50 to 60 knots are possible, but extreme gusts are rare. Surface winds in the southeastern regions of Alaska vary greatly in direction and force. because of the varying exposures and the highly irregular configuration of the coasts and mountains. The winds tend to follow the contours of the terrain and, thus, adjacent areas.can have average winds of opposite direction. High velocity winds probably occur in the area being studied. Above 2,000 feet MSL, high speed wind flows may occur from almost any direction, but the greatest prevalence seems to be from a southeasterly quadrant. Direct observations of peak winds near 2,000 feet above MSL were mace in the Juneau area during construction of the Snettisham project, where wind speeds in excess of 200 mph were observed. Additional calculations would be required to determine maximum wind velocity and direction relative to the location of a transmission system serving a selected: hydropower site. However, for preliminary design, winds in excess of 100 mph should be considered. Storms Because of the dominating maritime influence, thunder and hail storms rarely occur in the study area; however, the area is subject to heavy autumn and winter storms. These storms are cyclonic in nature and are generated by the semipermanent, Aleutian low pressure system. This cyclogenesis takes place as a result of the cold flow of southeasterly air from Asia, which generates a wave or series of waves on the polar front. These storms move eastward from their point of origin into the Gulf of Alaska, where they cause high winds and low ceilings for 2 to 3 days. Storms of this nature usually cause copious amounts of precipitation on the coastal mountain ranges. ice and Frost Icing Icing is rarely significant in the first few hundred feet of elevation; accumulations of over a few tenths of an inch are considered rare. From 1,000 feet above MSL and upward, both tne incidence and accumulation of ice increase rapidly. A 6- to 8-inch accumulation of ice on the windward side of objects probably occurs above 3,000 feet MSL. Moreover, the frequency of accumulations of an inch or more of ice probably increases to as much as twice a week during some intervals from late fall to early spring. Frost Frost penetration in the Ketchikan area will vary significantly from one site to another, dependent on such things as the nature of the soil, its water content, recent geology, and proximity to continental and maritime A-10 influences. In qeneral, there is little evidence of frost penetration of over 1 foot in the first 200 feet above-MSL.° The Environmental Atlas of Alaska indicates no permafrost near sea level in Southeast Alaska. . Snows lides In the higher elevations of. the study area, portions of the terrain are devoid uf snow cover for only short periods throughout the year. It has been estimated that snow depths, as a result of drifting, in excess of 20 feet may be reached at higher elevations. Snows of these magnitudes accumu- late on the precipitous.slopes of the drainage basin and at high elevations above the transmission line route until enough weight is accumulated to overcome the ‘shear: friction in the snow. At this time, the. snow begins to move, causing an. avalanche. These avalanches occur with great regularity at specific. places. in the local aréa and are apt to occur at any susceptible location. -.The snowslides denude the land of trees and loose ‘Surface material and are capable of destroying any structure not able to resist their tremendous force.. Winds created by displaced air move with blast velocity and:are capable of destroying buildings because of the rapid change. in differential. pressures. with respect to the inside and outside of a structure. Special care was taken in prospective routing of the transmission line and placement of project features to avoid the avalanche threat. ; STREAMFLOW RECORDS. . Several potential hydropower sites in southeastern Alaska have attracted the interest of private and government development agencies since the early years of this century. This interest is specifically reflected in the rather high density of stream gaging stations in the vicinity of Ketchikan and a substantial period of record for several of these stations. The U.S. Geological Survey (USGS) has published data for many of these stations and now actively monitors many other stations in the area. One or more of these stations has been in operation each year since 1916. The period of record and the drainage area for Upper-Mahoney and: Mahoney Creeks are : presented in Table A-2. ‘ Extension of Streamflow Record Stream discharge records are available throughout 1915 to cate on one or more. of the six gaged streams shown in Table A-2. An annual histogram over the period of extended record for the entire Mahoney basin is provided in Figure A-6. A-11 —===—= ee / Table A-2 . * “Stream Gaging Stations Drainage Aréa- Station not > (sq. miles): ~— Period of Record Grace Creek. near Ketchikan | 30.2. te Oct. 1927 - Sep 1937 ., ; Ba ; ; Se Aug 1963.- . 1969 Manzanita Creek‘near Ketchikan . (33.9 Oct’ 1927 - Oct 1937 . = ~ Aug 1947 - 1967 Ella Creek near Ketchikan » 19.7- Oct 1927 - Sep 1938 Oct 1947. - Sep 1958 Fish Creek near Ketchikan. — 32.1 “dun 1915 - Oct 1935 : - Oct 1938 - Present Mahoney Lake Outlet. near Ketchikan 5.7 Oct 1920 - Sep 1933 : / : Oct 1947 - Sep 1958 Oct 1977 - Present Upper Mahoney: Lake Outlet 2.1 Oct 1977 - Present near Ketchikan . Existing USGS streamflow records from ‘the Fish’Creek gaging station using linear regression correlation techniques were compared to determine the optimum equations for calculation of missing records for the Mahoney Creek gage near Ketchikan. Linear regression equations were prepared for Mahoney Creek on a monthly basis. Individual monthly streamflows were extended using streamflow data for the corresponding stream with recorded data that had the highest correlation coefficient. Records from the Fish Creek gaging station, because of the long period of record and accurate monthly correlation, were utilized to extend the record at the Mahoney Creek gaging station. The specific monthly equations are presented in Table A+3 and are also shown in Figure A-7. : A-12 ci-¥ 100,000 8 Annual runoff (acre-feet) tal Mahoney, Basin npual Runoff ~ ety d te Figure A-6. Gaged and synthesized streamflow at Mahoney Creek October i ; 101.1") November yer s @or fe ; TEA y = 1.30x - 0.73 December . Pe 0.03 y = 1.46x = 3.43 fT y*1.33e = 1.25 ‘rte 0.96 | Vahorey Creek cfs/mi? . 4 0 5 w 18-20 25 cu 9 $s 10 15 2 25 n 4 3). 10 7 7 fl Fish Creek cfs/mt2 7 Fish Creek cfs/mt . February March May ye Vite. 110 y = 1,30x= 1146 *| Fs 0.96 y © 1,20x + 2.94 s 8 “enoney Creek cfs/ni? R 1 Mohs) AG) =| 1S ceteatie | 2661 30 et iil, | does t6\ detente) ioe. ant se Fish Crees efs/mt? 59 duly Be hoof oe he cial LLOE ST september 7 nt ad Yo |e y = VAT + 6.52 2, 2 1T y erste + 6.85 ff S] oy © 1.28x- + 2.25 vs 0.88 : 3 rs 0.91 aay fee re 0.93 # 3 8 8 3 Maroney Creek cfs /ai? a a Mancrey creck cfs iri? 10 0 s 1 %& mM 2% mM O 5, 1 15 2 2% IW 4S 0 Fish Creek cfs/m{2 6 y «tw 2 mo wo el) | 0] | |88 | lea | 25) 4.90) | | Fish Creek cfs/mi* Figure A-7. Correlation analysis -- Mahoney Creek vs. Fish Creek A-14 = = ——$—— Ess Po Table A-3 : Mahoney Creek Correlation-with Fish Creek | . : , ; Correlation Mahoney Creek, Fish Creek (cfs) Coefficient October Mahoney’ Creek flows = 1.17 Fish Creek flows. +4.01 0.83 November Mahoney Creek flows = 1.30 Fish Creek flows. -0.73 0.90 December Mahoney Creek flows = 1.46 Fish Creek flows --3.43 0.98 January - Mahoney Creek flows ‘= 1.33 Fish Creek flows -1.25 0.96 February - Mahoney Creek flows = 1.29 Fish Creek flows . -1.10 0.96 March Mahoney Creek flows = 1.30 Fish Creek fiows -1.46 0.91 April Mahoney Creek flows = 1.23 Fish Creek flows -0.85 0.90 May ’- Mahoney Creek flows = 1.20 Fish Creek flows +2.94 0.90 June Mahoney Creek flows = 1.14 Fish Creek flows +10.06 0.81 July '° Mahoney Creek flows = 1.47 Fish Creek flows -6.52 0.88 August Mahoney Creek flows = 1.51 Fish Creek flows +4.85 0.91 September Mahoney Creek Jows =.1.28 Fish Creek flows +2.25 0.93 = = Because of 2 years of missing records at Fish Creek, additional correlations with Ella Creek were necessary to complete the extended record. Since these correlations..are of only minor significance, they are not included here. : : The elevation of the Upper Mahoney basin (average 2,350 feet) contributes to the abnormally high amount of precipitation that falls over the basin as well as the seasonal or monthly variance in runoff distribution. As shown in Table A-4, the winter precipitation generally exceeds the summer precipitation. However, the winter precipitation in the Upper Mahoney basin is mostly snow, which accumulates during the winter and melts from late spring through summer, contributing greatly to the high summer discharge reflected in the Mahoney Creek gaging station records. A-15 Table A-4 / Average Monthly Precipitation and Runoff, Mahoney Lakes Basin Mahoney Creek: - Period of. Record Avg. Precip. ' Mahoney Lakes Basin (inches /month) “Monthly Runoff (%) January . 7 44.4 6.7% February 12555 4.2 March , Ae2 3.8 April : 12.8 | 5.3 ~May . sao 9.7 June Tele 30.2 1.7 July 26.0 10.0 August . 19.8 9.0 September eee 3s 8.2 October 34.4 130 November ; Zoe, 9.9 December 20.5 7.9 Annual 259.8 100. 0% a — Seasonal runoff from the Upper Mahoney basin behaves considerably different than that which represents the composite basin. This is primarily due to the orographic effects on precipitation and the seasonal difference in snowpack accumulation between the upper and lower basins. Therefore, while the lower basin tends to shed precipitation in relation to influx, the upper basin will accumulate winter precipitation; which is then released into the lower basins as ablation occurs. Thus, tne percentage of flow recorded at the lower Mahoney gage, which also represents the Upper Mahoney basin contribution is variable throughout the year. In an effort to obtain realistic monthly distribution and average annual runoff from the Upper Mahoney basin, records from the highest gaging station in Southeast Alaska, Long Lake (1,000 feet MSL), were compared to records from nearby Speel River, which is a sea level gage. Upper Mahoney and Long Lake are both located in areas of maritime influence and have high, similar average basin elevations (2,350 feet for Upper Mahoney and. 2,700 feet for Long Lake). Although Long Lake has glacial input, from November through April the monthly distribution of inflow may be similar to what could be expected from the snow covered, southerly Upper Mahoney basin. The monthly distribution in Table A-4 was applied to:the appropriate month over the period of extended record from the Mahoney Creek gaging station. (For example, Upper Mahoney's February contribution over the period of extended record is estimated to be 22 percent of the flow at the lower gage.) When the Long Lake monthly percentage flow distribution is compared with Speel River, monthly flow distributions for the Mahoney basins, as shown in Table A-5 and Figure A-8, resulted. A-16 a = a — = = ee * Table A-5 Percentage of Total Monthly Runoff Attributable to Upper and Lower Basins From Upper Mahoney From Lower Mahoney V/ __.(%) _ etal) eiaiee October el el el 6X : : 54% November . . 30. 1 ee 70 December HY - 28 Ui : j Sere January eeeer2s : 75) February Le - 22 78 March — . Bales 24 76 April eo esd ane / 70 May : ; 40 60 June 55) 45 July 65 a 35 August i : 60 40 September. . — 55 ; 45 Average Annual. ; 43. 8% 56.2% 1/ Includes Upper Mahoney Creek basin. <= caren ee es The effect of this adjustment would be to generally reduce the winter flows and increase summer flows in relation.to the distribution indicative of the measured flow of the total basin. Sedimentation and Water Quality Although sediment and water quality data for the Mahoney Lakes basin are not available, the drainage.area characteristics of all the potential sites indicate a very low rate of sediment production. The upper area is predominately covered by muskeg and no glaciers or permanent.ice fields are in the area. i as Based upon the limited sediment data available for the area, the rate of sediment production for the drainage area is estimated to be about 0.1 acre- feet per square mile per year, or less. This corresponds to an annual sediment inflow to the Upper Mahoney reservoir of only 0.21 acre-feet per year, which is a negligible amount. -Tnere are no changes to sediment yield as an effect of possible future land use. The area proposed: for tne Mahoney Lakes project is void of any marketable timber. In view of the low sedimen- tation rate and projected location of the power intake works and dam, there are no anticipated sediment problems associated with Mahoney Lakes project features. Evapotranspiration The normal high relative humidity, high percentage of overcast. days, scarcity of trees in the upper basin, and relatively cool climate preciude any appreciable percentage of water loss from evapotranspiration. Estimates A-17 oN co et Moly Lenuue quacuag 3 5 e a 6 Zk © Upper Mahoney 43 R MAY JUN JUL’AUG SEP OCT NOV DEC JAN FEB MAR AP Monthly distribution of annual flow from A-8. Figure Upper Mahoney and Mahoney Lakes A-18 of flow were based on records from existing or historical gaging stations near the project areas. These records reflect any past evaporation, and for these reasons, no corrections were made in the runoff analyses for evaporation. The difference of 29 inches between the estimated average precipitation at Upper Mahoney and average runoff from Upper Mahoney: could be attributable to evapotranspiration. As shown in Table A-6, ‘average evaporation losses totaling 15.6 inches were observed. at the Juneau airport from May tarough September. ‘This may be somewhat indicative of evaporation losses that may occur in the project area. —— SS SS Table A-6 Evaporation.-Losses 1/ (inches) May June - © “uly August September ==— Total 3.31 3.65. -. 3.85 3/37 1.40 15.6 J/ Juneau airport, 1968 - 1978. = ee <== <== FLOOD CHARACTERISTICS Snowmelt Floods Tne proposed project site has flood peaks in the early summer that are predominately from snowmelt runoff. Tne magnitude of the spring flood peaks is dependent upon three conditions: (1) the amount of accumulated snow, (2) the temperature sequence during spring melt, and (3) the amount of precipitation. A large snowpack over the basin will give a large volume of runoff during the spring and summer; but, if the temperatures increase gradually, causing slower snowmelt, the flood peak will be just slightly above normal. However, if the early spring is colder than normal and the temperatures rise rapidly for a prolonged period, the flood peak will Probably be extremely high with the duration of flooding dependent upon the total snowpack. Rain Floods Rain floods produce the highest flows, which usually occur in the fall between late August and October. The flood peaks are quite sharp due to the fast runoff caused by the steepness of the terrain and the low infiltration losses into the underlying rock. Past Floods The maximum instantaneous recorded discharges from six gaging stations in the area are provided in Table A-7. ‘A-19 Station Grace Creek near Ketchikan Manzanita Creek near Ketchikan Ella Creek near” Ketchikan Fish Creek near Ketchikan Mahoney Creek near Ketchikan _ Table’ A-7 Maximum Instantaneous Recorded Discharges Discharge (cfs) - 3,990 "5,820 - oT Fag | 5,400" 2,530 Watershed Size “(mi2y: cfs/mi2 _ 132.1 171.7 87.3 - 168.2 443.9 Date 4 Sep 1966 14 Oct 1961 7 Dec 1930 15 Oct 1961 2 Feb 1954 The annual maximum instantaneous recorded dishcarges over the period of record at the Mahoney Creek gaging station are provided in Table A-8. - Table A-8 Annual Maximum Instantaneous Recorded Discharges at Mahoney Creek Water Year 1923 1928 1929 1930 1931 1932 1933 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 Annual. Peak Discharge (cfs) 1,850 762 1,460 1,920 2,400 1,250 1,090 1,210 1,260 1,640 970 866 842 2,530 1,640 1,530 838 - 1,350 31 12 21 13 20 31 21 11 20 20 “29 im Date Aug Oct Aug Nov Oct Oct Sep ‘Aug Sep Sep Jun Oct Oct Feb Aug Oct Dec Apr 1923 1927 1929 1929 1930 1931 1933 1948 1949 1950 1951 1951 1952 1954 1955 1955 1956 1958 A-20 Peak discharge frequency at the Mahoney Creek gage is shown. in Figure A-9. Because of the-small. potential. for heavy monetary loss if flooding would - accur, it is anticipated that a flood frequency of 10 years can be used for- design protection during the construction period.. The upper basin, using the September .contribution of 55. percent, would produce a peak flow of approximately -1,200 cfs. A summary hydrograph of the Mahoney Lakes basin, which provides minimum, maximum, and mean daily flows as well as max imum - instantaneous flow, is provided ¢ on Figure A- 10. = = — =a Table A- 9° ‘Mahoney Creek Flood Frequency _ Return: Fiood _ Interval ‘Magnitude _ _(years) (cfs) 2 1,304 5 1,785 10 ~ 2,125 20° 2,450 50 2,938 100 3,311 Probable Maximum Flood The U.S. Weather Bureau Technical Paper No. 47 gives general values of the 24-hour probable maximum precipitation (PMP) for the Upper Mahoney basin as approximately 24 inches. Applying these data to the upper basin necessitates special ‘consideration in view of the method used in calculating the PMP and the problems created by the limited high elevation observational data for Alaska. -The location of the Upper Mahoney basin, lying in line with the prevailing southeasterly storm patterns and coupled with the high elevation of the basin, contributes to the high PMP used in this study. The PMP used in deriving the maximum probable flood was obtained from the Hydrometeorological Branch, National Weather Service. The hourly distribution of accumulative and incremental rainfall and accumulative and incremental runoff is provided in Table A-10. A-21 Exceedence frequency per hundred years 0.01 0.1 10 20 70 60 50 95 90 80 98 ’ 1958). Frequency Curve was computed using the Log _ Pearson Type III Method. Frequency Analysis is based on 18 years al of record (1923,1928-1933 and 1948- ] pared 6000 5000 Exceedence Interval - Years 3000 2000 1000 sjo UL MOL4 A-22 800 200 _ Peak discharge frequency at Mahoney Creek Figure A-9. ee-v JANUARY Peanuany MARCH 2600.72 1218 1920 20 8 10 10 20 98 Aran 2.10 18 2028 8 10 Ly Avauer Period of Record: 10/1/22 - 11/31/27, 1/1/28 - 11/31/47, 1/1748 ~ 2/28/58 Ordinate values between 1200 and 2400 have been deleted, However, respective flows have been shown in parenthesis, iMihfili 2600 2500 Hl 2400 1200 100 1000 900 800 700 600 500 dad T AI tt La RR i) ER Mean Daily Flow 2 10 18 20 a5 JANUARY © 10 18 20 #8 reenvany (na Ninimum Daily Flow 8 10 19 20 a6 way 8 10 18 20 a8 mancn 810 18 80 28 ara 2 10 1 20 a8 June guy 2 10 19 20 28 8 10 18 20 20 Avouer 80 aoe og ourrewern ecto @ 10 18 20 a8 0. Orcemacn | Month [ Figure A-10, Summary hydrograph of the Mahoney Lakes basin . ‘Table A-10°°. : Rainfall Distribution of. the Probable Maximum Storm Accumulative. - Incremental . . WDNONGVODWWHOYOWO HWA nN .- Rainfall oie: 06 bs ee) -4 7 . . PODONWNVNVNHONUIHONWMTOH HOW OND ‘Time Rainfa (hrs) (inche ml 0. +2 I. 5 Ze cpa 3. 5 Ri 6 Ds 7 - 6. 8 Te 9 9 10 133 3 Ss 12 lias 13 Lite 14 18. 15 19. 16 19, 17 20. 18 20.4 19 Zul 20 21.8 21 ee) 22 230 23 23.7; 24 24.1 s)_- ~ -/_(inches) * " Recumulat ive Incremental - Runoff.” . Runoff ; (inches) (inches) . . . . . ole oe . ° NOWOP OP DWHONNMNDWOWWDWONSO. ny s COWDONNAMANAODMWNH——OO . 0.0 0.2 0.8 0.9 0.9 Tl 1.1 1.8 1.4 iE 4.0 1 2.5 15. 1.2 16. - 0.9 17. 0.6 17. 0.5 18. 0.5 18. 0.5 19. 0.4 20. 0.7: : 0.7 21.3 0.6: 21.9. 0.6 22.5: 0.6 22.9 0.4 — It was determined from Figure A-4 that 1.2 inches of precipitation would be lost through infiltration during the 24-hour probable maximum storm. | Following this infiltration loss, it was assumed that the soil would be saturated and, therefore, precipitation and direct runoff would be equal. The computing of hydrographs for ungaged basins is dependent on an estimate of the time of concentration (Tc -- time of travel from the most distant point in the basin to the point of interest of the basin). Time of concentration, base time, time to peak, and unit peak he paaila for the Upper Mahoney basin a re provided below. . 0.397 hr. L = 2.2 mi = 11,616 feet (channel length) H = 1,400 0 ft (diff. el. headwater to site) S = w = 1400 ft = 0.1205 L T1616 ft Gi LO-77 = 0.0013 (11.616)0.77 = $0. 385 (0.1205)0.385 A-24 A = 2.1 mi2 Q = 1.00 in. D = O.5 hr. Base Time: Tb = 2.67 Tp = 2.67x 0.49 = 1.30 hr. Time to Peak:. Tp = -9 + 0.6 Tc = 952+ 0.6 x 0.397 = 0.49 hr. Peak Discharge: Qp = “S5AQ . 48) 5 21 - 2074 cfs. The 24-hour PMP was applied to the unit hydrograph, which results ina probable maximum flood of approximately.5,000 cfs (Figure A-11). Because the dam is designed to be overtopped, a standard project flood (SPF) of 2,500 cfs: was-used in lieu. of the-probable maximum flood. As shown in Figure A-12, the SPF was routed through the reservior using assumed weir lengths of 100, 150, and 200 feet with peak outflows of 1,915, 2,075, and 2,100 cfs, respectively. As shown on the discharge-surcharge curve (Figure A-13), the surcharge resulting from the SPF at the spillway with weir lengths of 100, 150, and 200 feet would be 3.25, 2.70, and 2.50 feet, respectively. The storage versus discharge curves for weir lengths of 50, 100, 150, and 200 feet are shown in Figure A-14. This storage is held _temporarily because it is all above the wier crest. The outflow hydrographs for the SPF, with a wier controlled lake outlet, show how storage is temporarily held (Figure A-12). Area Capacity The capacity curve of the Upper Mahoney Lake reservoir is shown in Figure A-15. The curve shows that the total storage capacity of the lake is roughly 8,300 acre-feet at the normal outlet invert of 1,954 feet. If the existing lake surface were raised by 25 feet to. 1,979 feet MSL and a lake tap were installed at elevation 1,730, a net storage capacity of 9,100 acre-feet would be provided. A contour map of Upper Mahoney Lake is shown in Figure A-16. Low Flow Frequency As shown on the low flow frequency curve for the Mahoney Lakes basin (Figure A-17), an average annual flow of 76 cfs would have an occurrence interval of 500 years. The lowest average annual flow recorded over the 23-year period of record is 88.2 cfs, which, when applied to the low flow frequency curve, would have an occurrence interval of approximately 10 years. = = = — = tu 4 a < ao oO ae a Cheer ey Sere 4000 3000 (S49) gsouny A-26 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hr) 7 8 9 6 Probable maximum flood hydrograph for the Upper Mahoney basin -11. Figure A ée-V Runoff (cfs) 2500 2000 1500 1000 500 ee ee ee the Standard Project Flood i Inflow and Outflow Hydrographs for “inflow \\ : OutFiow 100 Ft. weir le . “Outflow 150 Ft. Keir... i \ SA fatto 200 FE Meth Te os c . Lie [ i if My ‘ oe 1 ‘ tS. : ALAS : a Te ea ee ee! SSNs Uae | Note: Outflow hydrographs for weir widths 1, of 100", 150", and 2007. ; 3 aie 6 7 8 9 ee a oe PaaS 16 PHOS Time (hr) : Figure A-12. Inflow and outflow hydrographs for the standard project flood Surcharge (feet) 0 1.5 3.0 i 4.5 200 150 100 50 1800 i 2000 2200 2400 Peak discharge (cfs) Figure A-13. Relationship of peak discharge and pool surcharge to spill- way width for a normal maximum pool elevation of 1,980 feet A-28 2500 (S$9) JOYVHISIG A-29 4000 6000 8000 10000 12000 14000" 2000 STORAGE Storage vs. discharge for weirs on Upper Mahoney Lake Figure A-14. oe-W Surface Area - Acres 0 130 120 0 100 90 80 70 60 s 2150 7] + tif 2100 Het eee of H rt t PEELE EE TEETER Sa AREA CAPACITY CURVE 2080 ft ; - t Ht Leper pg rege pers pea re 2000 Lake Surface Elevation 1954 Feet (MSL) -+ eee ja Elevation - Feet MSL 1e50 Ft A - oa or Elevation in feet {M.S.t.) z 1685 ; : aH 1700 1800 T 1725 op : 1750 775, 1800 1825 4 1 1850 1750 1875 : : 1900 1925 1950 SO euwnn— SESSRSESlewo Run comumenne 1700 1975 2000 107 2025 126 2050 a4 1650 Storage Capacity- 1000 Acre Feet Figure A-15. Area capacity curve for Upper Mahoney Lake reservoir 0 1 2 3 4 5 6 ? 8 ’ 10. uN Figure A-16. Upper Mahoney Lake Ze-4 Annual runoff (cfs) Exceedence frequency per hundred years 99 98 95 90 80 70 60 50 10 1 0.1 0.01 700 f- _ ptm 600 | SS EEE YEE fote: 1. Curve based on Annual Flows 500 W.Y. 1923-25, 1928-32 and 1948-57 400 ae 300 200 HH 100 90 80 70 60 50 40 30 20 Figure A-17. Low flow frequency curve for the Mahoney Lakes basin APPENDIX G RESPONSE TO COMMENTS Final Consultation Document RESPONSE TO COMMENTS ON INITIAL CONSULTATION DOCUMENT March 23, 1994 Office of Management and Budget Division of Governmental Coordination 1. No response needed. April 1, 1994 Ketchikan Public Utilities 1. Request for copies of agency correspondence. HDR responded to this request in a letter dated April 15, 1994. Copies of correspondence will be transmitted at key milestones in the FERC licensing process. It was also stated that, while not required, KPU would be copied on the 6-month status Teports submitted to the FERC. April 8, 1994 State of Alaska _ Office of the Governor 1. No response needed. April 13, 1994 Department of Natural Resources Division of Parks and Outdoor Recreation Office of History and Archaeology n No response needed. May 20, 1994 Tlingit & Haida Regional Electrical Authority 1. No response needed. May 20, 1994 Ketchikan Gateway Borough tL. No response needed. Mahoney Lake Hydroelectric Project August 1994 G-1 FERC No. 11393 Final Consultation Document May 21, 1994 Environmental and Natural Resources Institute 1. Data indicate that goshawks occur in the Mahoney Lake area. The effects of the project on Northern goshawks will be addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. June 3, 1994 State of Alaska Department of Fish and Game 1. It is important that the temperature and flow modeling and analysis be combined with the results of the fish studies in a manner that accurately predicts the effects that the project might have on fish productivity. Temperature flow and fish studies have been specifically designed to establish a baseline and allow prediction of project effects on fish productivity. We would also suggest more frequent monitoring of the Mahoney Lakes sockeye spawning cycle to more accurately determine the timing and abundance of this run. Monitoring Lower Mahoney Lake for returning adult sockeye during the summer will be increased to weekly visits by local observers beginning in late July and continuing through September. The biological team will conduct at least two detailed surveys of spawners based on feedback from the observers. Wildlife and botanical objectives are vague and should address the proposed mitigative measures to minimize potential collisions of large birds or electrocution of raptors with the overhead transmission line. Measures to mitigate potential adverse impacts of the overhead electrical transmission line on birds will be developed in consultation with resource agencies and will be incorporated into the project design. The transmission line is planned to be buried from the powerhouse to the switchyard, which is the area near the Lower Mahoney Creek outlet to George Inlet. From this point to the Swan Lake Intertie, the overhead transmission line will be designed using approved raptor electrocution-proof designs that prevent raptor impacts or electrocution. Request for 1983 Corps of Engineers DEIS referred to in the ICD. A copy of the 1983 Corps of Engineers DEIS was sent to Mr. Jack Gustafson on June 15, 1994. Mahoney Lake Hydroelectric Project August 1994 G-2 FERC No. 11393 Final Consultation Document June 8, 1994 Department of Natural Resources Division of Parks and Outdoor Recreation Office of History and Archaeology AC No response needed. June 9, 1994 U.S. Department of the Interior Fish and Wildlife Service 1 No response needed. as Recommendation that the above ground transmission line be located more than 1/8 mile from the shoreline, if at all possible. The above-ground transmission line will follow the alignment of the existing road for most of the route in order to avoid clearing a new, separate corridor. The transmission line will be buried around Lower Mahoney Lake from the powerhouse to the switchyard area within the new road. A survey will be conducted in cooperation with the USFWS to locate and determine activity status of bald eagle nests in the project area. June 17, 1994 National Marine Fisheries Service i NMFS jurisdiction is generally limited to marine species. U.S. Fish and Wildlife Service should be contacted for terrestrial and other aquatic species under their jurisdiction. Consultations with the U.S. Fish and Wildlife Service have been initiated. June 21, 1994 Office and Management and Budget Division of Governmental Coordination 116 NPDES Permit and Certificate of Reasonable Assurance The Applicant will apply for a NPDES Stormwater Permit, if required, and Certificate of Reasonable Assurance at the appropriate times in the FERC licensing process. Ze Request for more frequent monitoring of sockeye spawning in Mahoney Lake. See ADFG Response No. 2 Mahoney Lake Hydroelectric Project August 1994 G-3 FERC No. 11393 Final Consultation Document Office and Management and Budget Division of Governmental Coordination Comments Continued 35 Request for identification of streams used by fish. Tributaries to Lower Mahoney Lake will be surveyed for fish use as part of the lake study program. Request for more information on wildlife/botanical resources be provided. See ADFG Response No. 3 ADNR’s concurrence with request from ADFG for additional information about potential effects of the project on stream flows, temperatures, and relationship of flow regime to Sisheries. See ADFG Response No. 1 Request that the proportionate contribution of upper Mahoney Creek to the Lower Mahoney Lake inflow be calculated and that the effects of any reduced inflows to Lower Mahoney Lake be graphed as a post-project hydrograph. The requested calculations will be completed using simple calculations based on drainage basin areas. Information collected will be presented in a draft report and provided to the agencies of record for their comments. After review, any appropriate adjustments to the draft will be incorporated into the final report. Construction activities will require a local zoning permit. A local zoning permit will be obtained from the Ketchikan Gateway Borough before construction activities begin. June 21, 1994 U.S. Department of Agriculture Forest Service ie Geotechnical Data An erosion and sediment control study is proposed to take place during the summer of 1994 to evaluate the potential for erosion and sedimentation during the construction and operational phases of the project. Because most of the project features are underground, emphasis of the study will concentrate on the access road and identifying tunnel spoils disposal sites. The access road is located on lands owned by the Cape Fox Corporation. Most of the tunnel spoils disposal sites will be on Cape Fox lands, but one is likely to be on National Forest System lands. The proposed access road route will be flagged and surveyed up to the powerhouse location to visually identify any existing environmental Mahoney Lake Hydroelectric Project August 1994 G-4 FERC No. 11393 Final Consultation Document hazards which could affect the design, construction, and operation of the project. No test drillings, earth-disturbing activities, or geophysical testing (seismic or drilling) will be done. However, after the license is issued by the FERC, it may be desirable to conduct some geotechnical drilling. A new application to perform that work will be submitted to the USFS at that time. as Cultural Resources Chris Campbell of Cultural Resources Contracting, Inc. will conduct the cultural resources survey for the project. The permit application to conduct archaeological investigations on National Forest System lands has been forwarded to Ms. Campbell to complete and submit to the USFS. Like the anticipated approach for the erosion and sediment control study, the access road will be walked to the powerhouse location to visually identify any geomorphic features that could result in the discovery of potential cultural materials. The work is primarily to identify cultural resources and the project’s potential impacts on them. The survey design will be approved by the SHPO. A Special Use Permit will be obtained from the USFS, if required. 3. Wildlife The direct, indirect and cumulative effects of the project on the mountain goat population will be developed in consultation with the resource agencies and addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. No specific study of the mountain goats is proposed. A bald eagle nest survey will be conducted and the implications of its results will also be addressed in the license application. 4, Special Use Permits The only study equipment to be placed on National Forest System lands is a water temperature monitor near the proposed intake in Upper Mahoney Lake. The monitor consists of a cable suspended in the lake down to a depth of 110 feet and connected to a waterproof box along the shoreline. The box is about one cubic foot in size. Other study work for the project that will occur on National Forest System lands will consist of hiking, photographing, and observations. a. Fish The direct, indirect, and cumulative effects on downstream fish populations will be addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. Mahoney Lake Hydroelectric Project August 1994 G-5 FERC No. 11393 Final Consultation Document June 21, 1994 U.S. Dept. of the Interior Fish and Wildlife Service 1 American and arctic peregrine falcon subspecies may occur in the project area as transients. The effects of the Mahoney Lake Project on American and arctic peregrine falcons will be addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. Alexander Archipelago wolves are present on Revillagigedo Island and likely exist in the project area. The effects of the Mahoney Lake Project on Alexander Archipelago wolves will be addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. Marbled murrelet, northern goshawks, and harlequin ducks may occur in the proposed project area. The effects of the Mahoney Lake Project on marbled murrelets, northern goshawks, and harlequin ducks will be addressed in Exhibit E of the FERC license application and/or the Applicant-prepared Environmental Assessment. Mahoney Lake Hydroelectric Project August 1994 G-6 FERC No. 11393