HomeMy WebLinkAboutRivers and Harbors in Alaska Draft Interim Feasibility Report and Environmental Impact Statement Hydroelectric Power for Sitka, Petersburg Wrangell, and Ketchikan Alaska 1983RIVERS and HARBORS
in ALASKA
DRAFT INTERIM FEASIBILITY REPORT AND
ENVIRONMENTAL IMPACT STATEMENT
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Hydroelectric Power For Sitka,
Petersburg / Wrangell,
And Ketchikan, Alaska
JULY 1983
DEPARTMENT OF THE ARMY
ALASKA DISTRICr. CORPS OF ENGINEERS
POUCH 898
ANCHORAGE. ALASKA 99506
[PRAFT 1
RIVERS AND HARBORS IN ALASKA
DRAFT INTERIM FEASIBILITY REPORT AND ENVIRONMENTAL IMPACT,,.5TATEMENT
HYDROELECTRIC POWER FOR SITKA, PETERSBURG/WRANGELL, AND KETC~IKAN, ALASKA
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UNIVERSITY OF ALA
ARCTIC F''>.lVlRONME'NTAL INF
AND nrrl. Cf:NTE '1K' •
707 A STREET ANCHORAGE. ~LA . >
ANCHoRAGE. AlASKA 99S01 Est. 199,
U.S. Army Engineer District, Alaska
July 1983
ARLIS
Alaska Resources
Library & Information Services
lUlchorage,AJaska
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I DRAFT 1
SUMMARY
This report examines hydropower potential for Sitka, Petersburg/Wrangell,
and Ketchikan in Southeast Alaska. It appears that the Alaska Power
Authority will continue with hydropower evaluations at Sitka in the near
future and that the capacity of the Tyee project will meet the demand for
power in the Petersburg/Wrangell service area. Therefore, the focus of
this report is on the Ketchikan service area.
Ketchikan is a small cOlTJllunity located on Revillagigedo Island. Diesel
generators currently supply much of the power used by area residents. A
hydropower development on the Mahoney Lakes system has been proposed.
This tentatively recommended lS-MW project would include a lake tap and
dam at the upper lake, an underground and a surface penstock, a 4.9-mile
transmission line, and related services. The first cost of the
tentatively recommended plan is estimated at $43,927,000, which will be
cost shared in accordance with arrangements satisfactory to the President
and Congress.
DRAFT
Reservoir
MAHONEY LAKES HYDROPOWER PROJECT
PERTINENT DATA
Water Surface Elevation (feet MSL)
Maximum
Minimum
Usable Storage (acre-feet)
Hydrology
Drainage Area (square miles)
Average Annual Runoff (acre-feet)
Dam, Rock-Filled Steel Bin
He i g ht (f eet )
Spillway Crest Elevation (feet MSL)
Spillway Design Flood (cfs)
Dam Volume (cubic yards)
Tunnel
Tunnel Size, (feet)
Tunnel Length (feet)
Tunnel Grade
Penstock
Length (feet)
Diameter (inches)
Power Plant
Number of Units
Turbine Type
Installed Capacity (kW)
Net Head (feet)
Maximum
Critical
Generator Rating (kW)
Plant Factor (%)
Voltage (kV)
Powerhouse
Transmission Line
Voltage (kV)
Type
Length (miles)'
Conductor
Transmission Losses (%)
Project Output
Dependable Capacity (kW)
Fi rm Energy (MW)
Average Annual Energy (MWh)
Economic Data 1/
Investment-Cost
Annual Benefits
Annual Cost
Net Annual Benefits
Benefit-to-Cost Ratio
1,979
1,750
9,100
2. 1
34,750
25
1,979
2,030
5,000·
10' (horseshoe)
4,000
1 on 3.2
5,370
36
3
Impulse
15,000
1,880
1,580
5,000
30
13.8
Steel Structure on
Concrete Foundation
34.5
Wood Pole
4.9
#3/0 ACSR
14,400
38,090
51,390
2
$50,084,300
8,263,400
4,341,500
$ 3,921,900
1.9
1/ All costs calculated using the October 1982 interest rate of 7-7/8
percent.
, DRAFT ,
I DRAFT I
SOUTHEAST ALASKA HYDROPOWE~ DRAFT INTERIM FEASIBILITY REPORT
I NTRODUCT ION
Study Authority
Scope of Study
Study Participants
Prior Studies and Reports
The Report
Problem Indentification
NATIONAL OBJECTIVE
SITKA AREA
Study Area
Table of Contents
Population and Economic Characteristics
Power Generating Resources
Demand for Electricity
Comparison of Demand and Resources
Conclusions
PETERSBURG/WRANGELL AREA
Study Area
Population and Economic Characteristics
Power Generating Resources
Demand for Electricity
Conclusions
KETCHIKAN/METLAKATLA AREA
METLAKATLA
Study Area
Population and Economic Characteristics
Existing Power Generating Resources
Potential Power Generating Resources
Demand for Electricity
Comparison of Demand and Resources
Conclusions
KETCHIKAN
Study Area
Population and Economic Characteristics
Natural Resources
Demand for E1ectrictiy
Existing Power Generating Resources
Planned Power Generating Resources
Comparison of Demand and Resources
Planning Objectives
Screening of Potential Measures
Assessment and Evaluation of Alternatives
i
DRAFT
Page
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6
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8
10
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25
25
25
25
28
28
30
31
31
33
33
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39
41
45
46
46
46
48
52
Table of Contents (Cont)
COMPARISON OF DETAILED PLANS
Rationale for Designation of the NED Plan
Rationale for the Tentatively Selected Plan
The Tentatively Selected Plan
PUBLIC INVOLVEMENT AND COORDINATION
CONCLUSIONS
TENTATIVE RECOMMENDATIONS
Table
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Tabl e 11
Table 12
Table 13
Table 14
Table 15
Table 16
Table 17
Table 18
Table 19
Table 20
Table 21
Tables
Potential Hydroelectric Development in the
Petersburg/Wrangell Study Area
Estimated Energy Requirements for
Petersburg/Wrangell Compared
with Potential Hydropower Generation Capacity
Annette Island Population Projections
Metlakatla Area Historical Peak and Energy Demand
Metlakatla Area Electrical Energy Forecast
Ketchikan Study Area Population
Ketchikan Area Fisheries Harvest
Ketchikan Area Wood Products
Port of Ketchikan Waterborne Commerce
1981 Ketchikan Waterborne Commerce
Ketchikan Area Employment, 1980
Ketchikan Area Historical Generations
and Peak Loads
Ketchikan Area Electric Load Estimates·
Ketchikan Area Average Annual Generation by Plant,
1970-1980
Potential Hydroelectric Sites in the Ketchikan Area
Lake Grace Project, Pertinent Data
Mahoney Lakes Project, Pertinent Data
Tyee Lake/Swan Lake Transmission Intertie,
Pert i nent Uata
Mahoney Lakes versus Lake Grace, Comparison of
Pert i nent Data
Summary Cost Estimates, Mahoney Lakes
Hydropower Project
Real Fuel Escalation Rate and Value of Energy
ii
Page
66
68
68
69
76
77
78
21
23
27
30
31
35
36
36
38
38
39
41
44
45
51
54
58
63
68
73
74
-
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Appendix A
Aopendix B
Appendix C
Appendix D
Appendix E
Appendix F
Appendix G
Appendix H
Appendix I
I DRAFT I
Table of Contents (Cont)
Figures
Page
Study Area 2
Sitka Study Area 9
Sitka Area, Historic and Estimated Power Demand 11
Sitka Area Power Demand Estimates 12
Sitka Area Energy Requirement Forecast 14
Sitka Area Capacity Requirement Forecasts 15
Petersburg/Wrangell Study Area 18
KetChikan/Metlakatla Study Area 26
Metlakatla Power Market Forecast 32
Ketchikan Study Area 34
Historical and Estim~ted Power Demand, Ketchikan 43
Comparison of Power Demand with Existing Generating
Facilities 47
Compari son of Power Demand with Add it ion of the
Lake Grace Project to Existing Facilities 55
Comparison of Power Demand with Addition of the
Mahoney Lakes Project to Existing Facilities 60
Southeast Alaska Main Transmission Route· . 62
Comparison of Power Demand with Addition of .
the Tyee Lake/Swan Lake Intertie 64
Appendices
Hydrology
Foundation and Materials
Economic Evaluation
Mahoney Lakes Project Plan Description
and Cost Estimates
Lake Grace Project Plan Description and
Cost Estimates
Operati on, Ma i ntenance, and Rep 1 acement
Plans and Costs
Load Forecast
PUb.l ic Views and Responses
Statement Recipients
iii
[DRAFT 1
1 DRAFT I
SOUTHEAST ALASKA HYDROPOWER DRAFT INTERIM FEASIBILITY REPORT
INTRODUCTION
Study Authority
This study is in partial response to a resolution adopted by the Committee
on Public Works, United States House of Representatives, on 2 December 1970
under the title of Rivers and Harbors in Alaska. The resolution states:
Resolved by the Committee on Public Works of the House of
Representatives, United States, that the Board of Engineers for
Rivers and Harbors is hereby requested to review the reports of
the Chief of Engineers on Rivers and Harbors in Alaska published
as House Document Numbered 414, 83d Congress, 2d Session;
Southeastern Alaska, published as House Document Numbered 501, 83d
Congress, 2d Session; Cook Inlet and Tributaries, Alaska, published
as House Document Numbered 34, 85th Congress, 1st Session; Copper
River and Gulf Coast, Alaska, published as House Document Number
182, 83d Congress, 1st Session; Tanana River Basin, Alaska
published as House Document Numbered 137, 84th Congress, 1st
Session; Southwestern Alaska, published as House Document Numbered
390; 84th Congress, 2d Session, Northwestern Alaska, published as
House Document Numbered 99, 86th Congress, 1st Session; Yukon and
Kuskokwim River Basin, Alaska, published as House Document Numbered
218, 88th Congress, 2d Session; and other pertinent reports, with
a view to determining whether any modifications of the
recommendation contained therein are advisable at the present time.
Furthermore, this statewide water resource development authority was
limited by the following in Senate Report 93-1032 (26 July 1974) in
reference to hydropower and rivers and harbors studies in Alaska:
Additiona11y,the Committee urges the Corps to give high priority
attention to current ongoing studies and new studies that relate
to hydroelectric generation. Specific recommendations in
connection with current studies are stated herein.
The funds provided are to be used for initiation of an interim
report on the feasibility of meeting the hydroelectric power needs
of the Sitka, Ketchikan, and Petersburg-Wrangell area.
Scope of Study
This report investi~ates the energy needs of three study areas: Sitka,
Petersburg/Wrangell, and Ketchikan (Figure l)~ The report assesses all
energy alternatives applicable to these areas and determines the
alternatives that would be most responsive to the study objectives.
Study Participants
The following agencies and groups assisted the Corps of Engineers in the
preparation of this report.
ALASKA
STUDY AREA
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RlftRI Alii) HARIIOItI IN ALAIKA ':t:; c;c:-SOUTHEAST HYDROELECTRIC POWER INTERIM
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Alaska Power Administration
Federal Energy Regulatory Commission
U.S. Forest Service
U.S. Fish and Wildlife Service
Environmental Protection Agency
National Marine Fisheries Service
Alaska State Clearinghouse
Alaska Power Authority
Alaska Department of Environmental Conservation
Alaska Department of Fish and Game
Alaska Division of Parks
City of Ketchikan
Gateway Borough
Ketchikan Public Utilities
Cape Fox Corporation
Metlakatla Indian Community
Council Annette Island Reserve
City of Petersburg
City of Wrangell
Thomas Bay Power Commission
City of Sitka
Borough of Sitka
Prior Studies and Reports
1. Federal Power Commission and U.S. Forest Service, Water Powers,
Southeastern Alaska, 1947. This report listed 200 potential hydroelectric
power projects ranging in size from less than 10 to over 50,000 kW.
2. Federal Power Commission, Alaska Power Market Survey, various years
from 1948 through 1976. These reports summarize the then current electrical
energy use, project future ~emands, and assess power marketability for the
Territory/State of Alaska. The 1960 edition lists 225 undeveloped sites
over 2.5 MW in capacity, including 141 in southeastern Alaska. Sixteen are
in the Ketchikan vicinity and would aggregate an installed capacity of 138
MW. The 1974 edition contains a reduced listing of the 76 sites having the
most favorable economic potential, including 22 southeastern Alaska sites,
of which eight are in the Ketchikan vicinity and would aggregate 158 MW of
installed capacity (at 50 percent load factor). The later reports are
based on data and analysis from the Alaska Power Administration.
3. U.S. Bureau of Reclamation, Alaska, a Reconnaissance Report on the
Potential of Water Resources in the Territory of Alaska for Irrigation,
Power Production and Other Beneficial Uses, January 1952, H.D. 197, 82d
Congress, 1st Session. This report was based on the previously cited
Federal Power Commission report of 1947 and included Ketchikan area sites.
4. U.S. Bureau of Reclamation, Lake Grace Project, Alaska,
Reconnaissance Report, December 1965. This report recommend initiation of
more detailed studies ("feasibility grade investigations") based on the
favorable findings of the reconnaissance.
3
5. Alaska Power Administration, Lake Grace Project, Alaska,
Feasibility Report, January 1968. This report recommended authorization
for construction of the Lake Grace project with provision for certain
additional studies of fish and wildlife, coordination with the U.S. Forest
Service, and contractual arrangements with the cities of Ketchikan and
Metlakatla. The project was found economically superior to the Swan Lake
project, but it was recognized that both might eventually be constructed as
demand expanded.
6. R.W. Beck and Associates for the City of Ketchikan, Letter Report
on Electric Power Program, July 1974. This preliminary report concludes
that power from either Lake Grace or Swan Lake would be cheaper than from
the comparable oil (ired plant if construction capital could be found.
7. Robert W. Retherford Associates for the City of Ketchikan,
Ketchikan Public Utilities Comprehensive Study, August 1976. This report
contains present use data, projections of future needs, and possible
alternative developments, including existing and potential hydroelectric
projects.
8. R.W. Beck and Associates, Swan Lake, Lake Grace, and Mahoney Lake
Hydroelectric Projects, June 1977. This appraisal report evaluates
community power needs, existing modes of generation, and the potential
hydroelectric developments of Lake Grace, Swan Lake, and Mahoney Lake. The
Beck report found power costs of 67, 67.2 and 78.9 mills per kilowatt hour
for Swan Lake, Lake Mahoney, and Lake Grace, respectively, as opposed to
added diesel alternative costs of 90.8 mills per kilowatt hours. Swan Lake
was recommended for initial development since this larger project more fully
eliminates Ketchikan's reliance on diesel fuel generation. Generation 'costs
are about equal per kilowatt hour to Mahoney and regul at i on advantages are
obtained due to larger reservoir capacity and increased operational
flexibility. In July 1977 the Ketchikan City Council voted approval of the
Swan Lake project.
9. Alaska Power Administration, Takatz Creek Project, Alaska, January
1968. The report presented detailed feasibility investigations and a
recommendation for construction authorization of this project to serve the
Sitka area.
10. R.W. Beck and Associates, Analysis of Electric System
Requirements, City and Borough of Sitka, Alaska, April 1974." This study
determined that the Green Lake project was the most favorable installation
and that it should be brought into service as soon as possible.
Installation of a third unit at the Blue Lake project should be the next
increment, followed eventually by the Takatz Creek project.
11. Bureau of Reclamation, Thomas Bay Project, Alaska, November 1965.
This interim report concluded that the Thomas Bay project was financially
infeasible without the participation of Ketchikan, but recommended that it
be included in the long range planning of power supplies for Southeast
Alaska.
4
12. R.W. Beck and Associates, Analysis of Electric System
Requirements, City of Petersburg, Alaska, March 1974. The investigations
showed that installation of a second unit at the Blind Slaugh hydroelectric
project had technical and economic feasibility. The report also recommended
moving toward an all hydroelectric system, with Goat Creek as the likely
most favorable next increment.
13. R.W. Beck ~nd Associates, Thomas Bay Project, Appraisal Report,
November 1975. This report concluded that Thomas Bay power costs were
comparable to additional diesel generation and suggested a review of
smaller potential projects.
14. Robert W. Retherford Associates, System Review and Planning
Guidelines, Petersburg Municipal Power and Light, November 1976. In this
report, recommendations included repair work at Blind Slough, additional
diesel, and development of Sunrise Lake hydroelectric project.
15. R.W. Beck and Associates, Virginia Lake Project, Appraisal Report,
August 1977. This report for the Thomas Bay Power Commission concluded
that the Virginia Lake project was clearly the most economical of four
small projects studied. It was found to be economically comparable to the
Thomas Bay project and to diesel generation.
16. Federal Energy Regulatory Commission, Green Lake, Alaska, Project
No. 2818, February 1979. This final environmental impact statement was
prepared in response to the Sitka application for the proposed Green Lake
project.
17. U.S. Department of Energy, Alaska Power Administration, Ketchikan
Area Power Market Analysis, September 1979 (Rev. February 1980). This
report covers power market aspects for the Ketchikan and Metlakatla areas.
18. U.S. Department of Energy, Alaska Power Administration,
Snettisham-Ketchikan Trans~ission Design, March 1980. This study compares
the economics of DC and AC transmi ss i on systems for connect i ng hydropower
plants to service centers.
19. Federal Energy Regulatory Commission,Swan Lake Project No. 2911,
April 1980. This final environmental impact statement was prepared in
response to the Ketchikan Public Utilities proposal to'construct a 22-MW
hydroelectric project on Falls Creek and Swan Lake near Ketchikan.
20. Harding-Lawson Associates, Geologic Reconnaissance for Mahoney
Lake Hydroelectdc Project, Ketchikan, Alaska, March 1981. This report was
prepared for the Alaska Uistrict Corps of Engineers as a geological
reconnaissance for a proposed development at Mahoney Lake.
21. Federal Energy Regulatory Commission, Tyee Lake Hydroelectric
Project, FERC No. 3015, June 1981. This final environmental impact
statement was prepared in response to the Alaska Power Authority proposal
to construct a hydroelectric project with an installed generating capacity
of 20 MW on Tyee Creek in the Tongass National Forest near Wrangell.
5
22. Ott Water Engineers, Inc. and Black and Veatch Consulting
Engineers, Final Report, City of Sitka, Alternate Energy Study, February
1982. This reconnaissance study, prepared for the Alaska Power Authority,
assessed eXisting energy resources and uses in Sitka,forcasted energy
requirements to 2001, and identified means of supplying energy required in
the Sitka area.
23. Alaska Industrial Power Corporation, Application for Preliminary
Permit (FERC No. P-62ll-00), Thomas Bay Hydroelectric Project, March 1982.
24. Alaska Power Authority, Reconnaissance Study of City of Sitka
Alternate Energy Study, April 1982. This study addressed the thermal and
electric energy requirements for the people in Sitka.
25. Harza Engineering Company, Chester Lake Project Feasibility
Report, May 1982. This study, which was prepared for the Alaska Power
Authority and Metlakatla Power and Light, includes a review and update of
the existing Chester Lake project, considers alternaitve developments, and
reviews economic and financial analyses of the various heating and
electricity technologies .
. 26. Teshmont Consultants Inc., Southeast Alaska Intertie DC
Transmission System, November 1982. This reconnaissance design and cost
estimate was authorized by the Alaska Power Administration to provide
feasibility and economic estimates for several transmission schemes.
27. EBASCO Services Incorporated, Kake-Petersburg Int~rtie, Draft
Routing and Environmental Report, November 1982. This report is one of
four reports prepared for the Alaska Power Authority to assess the
feasibility' of the various options for meeting Kake's electricity needs.
28. Application for Preliminary Permit (FERC No. P-6856-000), Thomas
Bay Hydroelectric Project.
29. EBASCO Services Incorporated, Kake~Petersburg Intertie, Draft
Feasibility Report, November 1982. This report, contracted with the Alaska
Power Authority, evaluated alternative means for meeting the electricity
requirement for Kake.
The Report
This interim report is divided into a main report, an environmental
impact statement, and supporting appendices. The main report addresses
each of the three study areas: . Sitka, Petersburg/Wrangell, and Ketchi kan.
The appendices include technical discussions on hydrology and foundations
and materials, as well as regional economic information, project
description and cost~stimates, power studies and economics, the U.S. Fish
and Wildlife Coordination Act Report, marketability analysis, operation and
maintenance plans and costs, and pertinent correspondence.
Problem Identification
The primary concern of Southeast Alaska residents is to reduce or stabilize
the.ir electricity costs. Demands for power have increased and will
continue to grow because of the expanding economy in this area.
6
NATIONAL OBJECTIVE
Congressional acts of the last decade have directed Federal land and water
resources planning to incorporate a multi-objective planning process.
Promotion "of the quality of life for the local public is the focus of the
planning objectives. These objectives are used to evaluate the
alternatives on the basis of equally weighted economic, social, and
environmental assessments. The Federal objective of water and related land
resources planning is to contribute to national economic development that
is consistent with protecting the Nation1s environment pursuant to national
environmental statutes, applicable executive orders, and other Federal
planning requirements.
7
SITKA AREA
Study Area
Sitka is located in Southeast Alaska on the west coast of Baranof Island
and is approximately 95 miles southwest of Juneau (Figure 2). The city
spans an area between the relatively flat delta at the mouth of the Indian
River to the mountains that rise sharply inland from the coast.
The City and Borough of Sitka have a maritime climate, with heavy and
frequent precipitation throughout the year and gradual temperature
variations. The mild temperatures and heavy rainfall in the area have
fostered dense rain forests that extend from timberline (2,400 feet) to the
shoreline. Predominant tree species are hemlock, spruce, and cedar.
A wide range of land and marine life inhabits the area surrounding Sitka.
Marine life includes: clams, abalone, salmon, halibut, crab, whales,
porpoise, seal, and sea lion. Sitka black-tailed deer, which abound on
Baranof Island, are common. Grizzly thrive on the island's berries and
fish from the streams and beaches. Other mammals include mountain goats,
beaver, deer, and mink.
Population and Economic Characteristics
In general, Sitka is a growing area, a fact that is reflected in its
population figures. The 1970 census reported a population of 6,424 for the
region and the 1980 estimate was 8,500 persons. With some employment
increases expected in the fishing and tourist industries, it is expected
that the population in Sitka will see continued growth.
Sitka lies within the Tongass National Forest, which provides the area with
its most important ~conomic resource --wood products. Alaska Lumber and
Pulp Company is the largest private employer in Sitka, with approximately
550 persons employed at the company in 1980.
The State, Federal, and local governments in Sitka provide jobs for over
800 people in the area. The Bureau of Indian Affairs school and U.S.
Public Health Service hospital are on nearby Japonski Island. Other
government employers are the U.S. Forest Service, U.S. Coast Guard, and
Alaska State Troopers.
The fishing industry represents a significant facet of the local economy.
Sitka Sound Seafood handles salmon, halibut, bait herring, black cod, ling
cod, and tanner, king, and dungeness crab.
Tourism has become another major industry in Sitka in recent years as the
Sitka area is one of the most scenic in Alaska. Two new hotels were
completed in 1978, which expanded the city's tourist and convention
8
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capacities. The tourist season usually begins in May, ends in September,
and centers around Sitka's rich historical resources and hunting and sport
fishing opportunities.
Power Generating Resources
Sitka's electrical power requirements are served by a combination of
hydroelectric and diesel generation. The City of Sitka owns and operates
the Blue Lake and Green Lake hydroelectric projects. The Blue Lake
project, a development on Blue Lake about 5 miles east of Sitka, became
operational in 1961 and provides 6,500 kW of dependable capacity and
30,800,000 kWh of firm annual energy. The Green Lake hydropower project
began operation in March 1982 and is located on Silver Bay, 12 miles
southeast of Sitka. This project has two 8,250-kW units providing 13,500
kW of dependable capacity and 46,500,000 kWh of firm annual energy.
The balance of Sitka's generation facilities is from diesel fired internal
combustion units located near the center of Sitka. Currently, there are
three units, rated at a total of 800 kW, that were installed before 1960, a
2,000-kW unit installed in 1968, and two 2,750-kW units installed in 1979.
The smaller units installed before 1960 are old and essentially used for
standby capacity reserves. Total installed capacity is 8,600 kW for diesel
and 26,550 for hydropower. Total dependable capacity is 27,500 kW, with
77,300,000 kWh of firm energy.
Demand for Electricity
Sitka's annual growth rate in energy and peak demand averaged 6 percent and
4 percent, respectively, during the 1960 's and 1970 's. The City of Sitka
projected a 6 percent long term growth rate. This 1979 projected load
forecast is shown in Figure 3. The most recent peak power demand was
approximately 11,000 kW with the total energy demand for 1981 of 51,000,000
kWh.
The most recent energy study for Sitka (Ott Water Engineers, Inc., February
1982) used an annual population growth rate of 2.3 percent to compute the
energy forecast. The population forecast was based on records of recent
growth over a period of varied economic activity and development. The
extreme population growth rate projections were 1.9 to 2.8 percent.
The quantity of energy used by commercial facilities was assumed, in the
Ott Water study, to be directly proportional to population growth. The
residential demand was dependent also upon a general increase in electrical
use per customer and the rate of changeover from oil heat to electrical
heat. Figure 4 compares maximum and minimum electrical energy use
projections from the 1982 study. The significant difference between the
maximum and minimum use forecasts resulted mainly from the cost difference
between electrical heating and oil heating. If electrical rates do not
increase as fast as oil costs, houses will continue to switch from oil to
electrical heating. Demand will reach the maximum level indicated unless a
lower cost alternative fossil fuel can be utilized. No practical lower
10
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20
ESTIMATED ENERGY DEMAND GREEN LAKE
AVERAGE ANNUAL
ENERGY
BLUE LAKE AVERAGE ANNUAL ENERGY
10
30~-------------------------------------------------------------,
NOTES:
25
: 20
" '" W
ESTIMATED CAPACITY DEMAND plus RESERVES
V'
II. 1°lF..~.~.~.~.~.rr.~.~.~.~.~.~.~.~TW~.~~rr~~~~rr~rw~~.~.~.~.~.!!.::::::::::: ::::::::::::::: EXl~~T·ING '" "'I~SEi ~S:::::· ..• ::::::::::::: •..........•...... ~ ...... v.~ ... ~ .. , .••••.••••....••••.• .. ...... ...... ... . .............•
BLUE LAKE
YEARS
I. Hydroelectric plant energy is overage annual delivered 01 the load
2. Power years extend from July I through June 30.
center.
:::::::::::::::::::::::~r: .........••••......... ~ ...
::::::: DIESELS :: ••• ::::: ...•.•.......... . ...... . •............. ............ ........•• . ............ . ........ ~.:::::::::::::::: .... . .................. .
•• ~ •••••••••••••••••••••• r
. . .....
ESTIMATED
CAPACITY DEMAND
3. • indicates actual valut.
4. Growth rate is 6% for projected peak load5 and
energy requirements.
SITKA AREA, HISTORIC AND
ESTIMATED POWER DEMAND
SOURCE: FERC, GREEN LAKE FINAL E I S., FEB. 1979 1979 STUDY
ftIP.I IIiIiII
Figure.
RIVERS AND HAltBOAS IN AlISP(A
UlArmy~ SOUTHEAST HYOROElECTRIC POWER INTERIM
GfE ........
Alaska Dlstnct
3
r-A. 1968 TAKATZ CREEK PROJECT STUDY r---1979-R. W. BECK STUDY B.
4 r--C. CURRENT STUDY MINIMUM
3 r---D. CURRENT STUDY MAXIMUM
252
2
I
D /J
/
100,000 / /
~ 3 A A .~ C . ' ~-~ . ..",.. 7 .' /j'-" U) 6 a:: i ~ .....
::::> 5 50 0 // U) ~ 4 40 ~/ 01"
~
~ 3 / 30 ~ ti /' ,
/1' ~ ~ /
" (!) m 2 ( A/ ~~'.. 20 UJ
.>' :E
:E
USAGE7 I ,~7 .'" ".
I j ~ ...... ~ ~ 10,000 , I I 10
9 , ." I 9 8 " -' 8
7 ~ 7
/ 6
I DEMAND
!5 ,
J 4
/'
/ 3
2
----PROJECTED
HISTORICAL
I I ~
1950 1960 1970 1980 1990 2000
1
) 2010
2001
YEAR
NOTE: Historical includes electricity sold to Alaska Lumber and Pulp,
Giso projections include 12% line loss and company usage.
SOURCE: OTTWATER ENGINEERING, JANUARY Itle2
SITKA AREA
POWER DEMAND ESTIMATES
1982 STUDY
Figure. m 1·11
RIVE"S AND HA".O"S IN At ASKA 4 us Army c:-SOUTHEAST HYDROELECTRIC POWER INTERIM
GfE....-.
Alaska Dlstnct
cost alternative fossil fuels have been identified. If the changeover from
oil heat to electri~ heat continues at the historic rate, energy demand
will continue to grow at about 7 percent per year until all oil heating
systems would be converted by the end of the year 2001.
Comparison of Demand and Resources
The Alaska Power Authority·s reconnaissance study of alternative energy for
the City of Sitka (April 1982) states,II ... the continuation of conversion to
electric resistance heat and the addition of new homes with electrical
resistance heat will use all the energy available from Blue Lake and Green
Lake hydroelectric projects by 1988.11
Figures 5 and 6 show the comparison of the total firm energy and capacity
from the Blue Lake and Green Lake projects with the three projections for
electrical growth of the Ott Water Engineers, Inc. study (February 1982).
Projection A assumes the 7 percent per year growth in electrical
comsumption will continue and that all heating will be provided by
electrical resistance by the end of 2001. Projection B uses the same rate
of conversion from oil as Projection A and assumes that heat pumps will
replace oil heat.by the end of 2001.
A comparison of Projections A and B, the most reasonable range of growth to
expect, with firm energy available from existing hydropower w0uld have
demand exceeding supply as early as 1988 but certainly before 1991.
Capacity demand would exceed the dependable capacity of existing hydropower
as early as 1992, but certainly before 1996.
Pri or to the Green Lake hydropower project comi ng on li ne, di ese 1 units
were used to supply energy required above that supplied by Blue Lake.
These qiesel engines were not designed for continuous operation, but were
intended to be ~sed for peaking and backup only. With Green Lake on line,
the diesels are used for peaking and backup and are not included for
planning purposes for meeting projected power demands.
Electrical power demands beyond the capacity of the Blue and Green Lake
projects could be accommodated by additional hydropower projects. The most
favorable follow-on project appears to be the Takatz Creek project on the
eastern shore of Baranof Island, about 20 miles east of Sitka. The Bureau
of Reclamation completed a favorable reconnaissance report on the project
in 1965 and the Alaska Power Administration recommended project
authorization in 1968 after 2 years of feasibility investigations. R.W.
Beck and Associates conducted additional evaluations of the project in 1974
and found that it was an economical hydropower project. The plan of
development called for construction of a concrete arch dam near the outlet
of Takatz Lake and a power plant near tidewater on Takatz Bay. The
proposed power plant contained two 10,000-kW generating units with a 55
percent plant factor and average annual generation of 106,900,000 kWh.
Other identified hydropower projects are Carbon Lake, with an estimated
capacity of 13,500 kW, which is 7 miles south of Takatz Creek, and Makoutof
River, about 40 miles southeast of Sitka, with an estimated capacity of
24,400 kW.
13
4
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0:: Y ~
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2
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Ixl04
1960 1970 1980 1990 2000 2010
2001
YEAR
A. TOTAL ELECTRICITY REQUIRED USING A FULL D. FIRM HYDROELECTRIC ENERGY FROM BLUE LAKE
CONVERSION FROM OIL HEATlNG TO ELECTRICAL AND GREEN LAKE.
RESISTANCE HEATING BY 2002. E. HISTORICAL USAGE.
B. TOTAL ELECTRICITY REQUIRED USING A FULL NOTE: Does not include electricity sold to Alaska
CONVERSION FROM OIL HEATING TO ELECTRIC Lumber and Pulp, olso includes 12% line
HEAT PUMP HEATING BY 2002. loss and compony use.
C. TOTAL ELECTRICITY REQUIRED USING THE SAME SOURCE: OTTWATER ENGINEERING, JANUARY 1982
PROPORTION OF OIL AND ELECTRIC HEATING
AS NOW EXISTS.
SITKA AREA
ENERGY REQUIREMENT FORECAST
Figure, III " .,
RIVERS AND HARBORS IN AlAS",A 5 us A,..", eorp. SOUTHE~ST HYDROElECTRIC POWER INTERIM
oIE.....-.
AIa9ka. Dlstrlcl
OIUf
•
40 / 30
25 Y ~
0 ~~4~ 20 ---
15 ~ V~'
~ ~
/~
~~
10 ~' en 9 /' l-S I-,/ <[ 7 ~ E.....-<[ 6 <.!)
// IJ.J
~ 5 . .r
4
//
~
3
2
0
1960 1970 1980 1990 2000 2010
2001
YEAR
A. TOTAL GENERATION CAPACITY REQUIRED USING A FULL D. FIRM HYDROELECTRIC GENERATION FROM
CONVERSION FROM OIL HEATING TO ELECTRICAL BLUE LAKE AND GREEN LAKE.
RESISTANCE HEATING BY 2002. E. HISTORIC USAGE.
B. TOTAL GENERATION CAPACITY REQUIRED USING. A FULL NOTE: Does not include electricity sold to Alaska
CONVERSION FROM OIL HEATING TO ELECTRICAL HEAT Lumber and Pulp, also includes 12% line
PUMP HEATING BY 2002. loss and company use.
C. TOTAL GENERATION CAPACITY REQUIRED USING THE SOURCE: OTTWATER EN61NEERING, JANUARY 1982
SAME PROPORTION OF OIL AND ELECTRIC HEATING
AS NOW EXISTS.
SITKA AREA
CAPACITY REQUIREMENT FORECASTS
Figure. m .,."
RIVERS AND HARBORS IN Al ASKA 6 us Army c:...,.. SOUTHEAST HYDROElECTRIC POWER INTERIM
"'E~
Alaska o.stnct
Conclusions
The projected electrical power demand for Sitka would exceed the firm
energy capabilities of the existing generating facilities as early as
1988. Studies by the Corps of Engineers and others have identified
potential hydropower projects that may meet those future needs; the Takatz
Creek site would be the most feasible project.
The Alaska Power Authority, in. their April 1982 reconnaissance study,
recommended that a detailed feasibility analysis be conducted to determine
the alternative energy needs of the Sitka area and identified some of the
major areas that need addition~l analysis, including:
·a core drilling program to supplement previous work on the Takatz Creek
project completed by the Alaska Power Administration (1968) to better
define the geological conditions at the dam, tunnel, penstock, and
powerhouse sites, along with a soils and foundation assessment for the
transmission line,
·a transmission line corridor climatological evaluation to determine
wind, ice and snow loads, and
·environmental studies to determine the impacts to the fisheries and
wi ldl ife.
The proposed feasibility analysis would require approximately $1.6
million to complete. It appears that the Alaska Power Authority will
continue with these evaluations in the near future. If they do not proceed
with further studies, additional study by the Corps of Engineers may be
warranted.
16
PETERSBURG/WRANGELL AREA
Study Area
Petersburg is located on Mitkof Island midway between Juneau and Ketchikan.
Wrangell lies about 32 miles southeast of Petersburg near the mouth of the
Stikine River. These two load centers (Figure 7) will be interconnected by
submarine crossings between Wrangell and Mitkof Island; thus, they are
considered as a single study area for the purposes of this report.
The communities of Petersburg and Wrangell are within the mountainous region
of the Coast Range of Southeast Alaska. These mountains are crossed by
numerous deep valleys and fjords. The mountain slopes throughout the region
are vegetated primarily by coniferous forests. Large muskeg areas are
common and are found on poorly drained slopes. Of the coniferous trees in
this area, four species are sought for commercial harvest: western
hemlock, Sitka spruce, western red cedar, and Alaska cedar.
Petersburg and Wrangell are within the maritime climate zone, so that both
have moderate temperatures but high levels of precipitation. January
temperatures in this part of Southeast Alaska average 28°F and in July the
average is 56°F. Average annual precipitation is 106 inches in Petersburg
and 82 inches in Wrangell.
Wildlife in the area include small groups of mountain goat, black and brown
bear, occasional coyote and red fox, wolverine, marten, weasel, mink,
otter, and others. No endangered or threatened species of plant, fish, or
wildlife reside in the general vicinity (U.S. Fish and Wildlife
Service, 1983).
Population and Economic Characteristics
Petersburg
The Petersburg area, which. includes the City of Petersburg and the related
area of economic activity, encompasses approximately 2,000 square miles.
Approximately 2,200 people (1980 census) reside in or adjacent to
Petersburg, with another 200 residents in the outlying areas.
Generally, the economic characteristics of this area h~ve'changed little
over the last two decades. Fishing· and fish processing have been and remain
the primary industries. Forest products and tourism are also important.
Although the fisheries resources in Southeast Alaska have declined in the
past few years, they are still the number one resource in the Petersburg
area. The local fisheries interests are attempting to establish a
bottomfish industry in Southeast Alaska to utilize such bottomfish species
as pollock, cod, and flounder.
Crystal Lake Hatchery is located 17 miles south of Petersburg and also plays
a part in the fisheries economy of the area. The hatchery's weight produc-
tion capacity is 100,000 pounds of fingerling and/or smolt, and the four
species raised are coho and king salmon and steel head and rainbow trout.
17
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SCENERY CREEK
PROPOSED
THOMAS BAY
PROJECT
RUTH LAKE
1\
56'15'
North
STATUTE MILES .. In
131'30'
West
131"30'
West
,"
56'15'
North
!
The logging industry also plays a vital role in Petersburg's economy. The
U.S. Forest Service continues to maintain their proposal for 200 million
board feet sales annually in the Petersburg area.
State and Federal agencies contribute year-round economic stability to
Petersburg. Because fishing and logging are seasonal industries, the
governme~t employers playa large role in Petersburg's employment. Some of
the government agencies represented are the U.S. Forest Service, Alaska
Highway Department, Alaska Department of Fish and Game, U.S. Fish and
Wildlife Service, and U.S. Coast Guard.
Tourism is an economic resource that is in the beginning stages of develop-
ment in Petersburg. Some public facilities to attract tourists are in the
development stage while others are in the planning stage.
W range 11
The City of Wrangell has grown steadily from a population of 1,315 in 1960
to 2,184 in 1980. Wrangell's economy is based primarily on logging and the
wood products industry. Additional sources of economic strength are derived
from employment in fish processing, institutional services, tourism, and
transportation.
Because Wrangell's economy is so heavily based in wood processing, it does
not exhibit the extreme employment seasonality characteristics of most
small Alaskan communities. However, Wrangell is included in the Wrangell-
Petersburg Labor Oistrict, which exhibits the most extreme degree of
seasonality of any other labor district in Southeast Alaska, because
Petersburg is heavily dependent on the seasonal fish processing industry.
Average employment for the Petersburg/Wrangell area is over 2,500, with the
largest employers being the Federal, State, and local governments.
Construction, then manufacturing, are the next largest employers.
The two lumber mills in Wrangell, the Alaska Pacific Lumber Company and the
Wrangell Lumber Company, produce a little over half of Alaska's lumber
exports. In addition to mill employees, loggers operating in the Wrangell
area contribute to Wrangell's economic base.
Wrangell's fishing and fish processing industries have been a major source
of economic strength since the first processing plants were established in
this area during the 1880's. However, the nature of the local fishing
industry has changed since the early days, when production was almost
exclusively centered around salmon. Salmon is still a major product, but
the successful introduction of shrimp processing has added another
dimension to the community's fishing industry. Other important fisheries
resources are dungeness crab and halibut.
Wrangell is currently benefiting from mineral exploration and development
activities in its traditional role as a transshipment point. It is possible
that significant increases in employment in Wrangell could result from the
development of the area's copper deposits.
19
Tourism has increased as another economic asset for Wrangell, as Wrangell
has many scenic, cultural, and recreational opportunities to offer the
tourist. Wrangell's greatest source of tourists travel to the area via the
Alaska Marine Highway ferries and Canadian cruise ships.
Power Generating Resources
Petersburg uses both hydroelectric and diesel generated electricity. The
Blind Slough hydroelectric plant has a dependable capacity of 1,600 kW and
produces about 64 percent of the community's energy. The diesel generated
capacity totals 6,030 kW (nameplate rating) from six units ranging in size
from 350 to 2,100 kW. All generation at Wrangell is from eight diesel
generators with a total nameplate capacity of 7,750 kW. Several generators
are due for retirement beginning in 1985 and would have to be replaced at
that time. The combined existing generating facilities of Petersburg and
Wrangell could have sufficient capacity to meet demand until 1987 if a
transmission line between the two cities were constructed.
During the late 1970's, the communities of Petersburg and Wrangell, through
the Thomas Bay Power Commission, started development of the Tyee Lake hydro-
electric project, which the Alaska Power Authority had under construction
in 1982. The Tyee Lake project (FERC No. 3015-Alaska) would meet the
forecasted peak electric energy demand of the Petersburg and Wrangell areas
in 1986 and would supply all of the electric power requirements for these
two communities through the year 2000.
The ryee Lake project's main features would be located on the Alaskan
mainland approximately 40 miles southeast of the City of Wrangell. The
powerhouse would be on Tyee Creek near the head of Bradfield Canal with the
lake tap intake structure in Tyee Lake. Stage one installed generating
capacity would be two 10,000-kW units with a dependable capacity of 14,800
kW. The first stage is expected to go on line in 1984 and would co~nect
the two load centers by submarine cable. Provisions would be made in the
Tyee Lake powerhouse for the future installation of a third 10,000-kW
generating unit, which would then meet the combined needs of Wrangell and
Petersburg through the year 2000. Existing diesel generators would be
maintained to provide standby emergency capacity only. The 130,000 t"1Wh per
year firm energy capability of the project would supply all requirements
for both base and peak power.
The proposed Tyee Lake project was selected from a feasibility analysis of
10 hydroelectric and six nonhydroelectric alternatives. Swan Lake at
Thomas Bay was the only other viable hydroelectric alternative and a
woodwaste generation proposal was the only viable nonhydroelectric
alternative to the Tyee Lake project that was identified in that analysis.
The Swan Lake site is now known as the Thomas Bay project (not to be
confused with the FERC Project No. 2911 that is being developed for
Swan Lake in the Ketchikan study area). The Alaska Industrial Power
Corporation has an application for a preliminary permit (P-621l-000,MarCh
1982) for the Thomas Bay project. The proposed project would be located on
the mainland at Thomas Bay about 16.5 air miles northeast of Petersburg.
The project would consist of a lake tap into Swan Lake with the powerhouse
20
-
on Cascade Creek. The powerhouse would contain four 8,500-kW units (34,000
kW total) that would produce 170,000 MWh annually. This potential project
would connect into the electrical system at the City of Petersburg but
would transmit energy through proposed and existing transmission lines from
Petersburg to a U.S. Borax Company mining development southeast of
Ketchikan. Because the planned 34-MW installation is less than the base
load con:inuous demand required by the U.S. Borax installation, it is
anticipated that the full annual energy capable of being produced by this
project would be used by the U.S. Borax Company.
The City of Petersburg also has an application for preliminary permit for
the Thomas Bay project before FERC (P-6856-000, November 1982). This
project would have a rated capacity of 44,000 kW with an average annual
energy of 200,000 MWh. (The capacity and energy figures are based on a net
average hydraulic head of 1,370 feet and represent only preliminary
estimates.) The city proposes to also transmit all energy generated at
Thomas Bay to the proposed U.S. Borax ~ine.
Other potential hydroelectric developments in the study area are listed in
Table 1.
Table 1
Potential Hydroelectric Development in the Petersburg/Wrangell Study Area
Gross
Project Stream Head (ft.)
Cascade Creek Cascade Creek 1,514
Goat Lake Goat Lake 1,240
Scenery Lake Scenery Lake 957
Ruth Lake Delta Creek 1,350
Virginia/
Sunrise Lakes Mill Creek 105/2,000
Anita/
Kunk Lakes Kunk Creek 2,160/275
Thomas Lake Thomas Creek 250
Wilkes Lakes 2,060
1/ Firm energy = 179,600 MW.
Potential
Installed
Capacity (kW)
48,000
25,000
18,000
15,000
9,000
8,000
4,000
1,500
Source: International Engineering Company, Inc., 1980.
21
Estimated
Average Annual
Energy (I~Wh)
199,800 1/
97,900
91,900
62,800
39,400
33,550
15,900
6,500
The woodwaste generation alternative would probably be located near Wrangell
and a woodwaste supply. This alternative would have an installed capacity
of 20,000 kW with a dependable capacity of 17,700 kW. It would require
approximately 37,600 tons of woodwaste for the first year of operation.
Although this woodwaste steam electric project is considered economically
and technically feasible, it is not as economical as either the Tyee Lake
or th~ Thomas Bay projects.
Demand for Electricity
The "Definite Project Report," prepared in 1979 by the International
Engineering Company~ Inc., gives historic peak demand data for 1960 to 1978.
Using the last 6 years of the demand data (1973 to 1978), the average annual
growth rate in peak demand is 5.92 percent per year. In preparing their
"expected case" forecasts of future peak demands, the International
Engineering Company assumed that this growth rate, rounded to 6 percent,
would continue until 1990. From 1990 on, they assumed that the annual
growth rate in peak demand would drop to 4 percent.
Region X of the U.S. Environmental Protection Agency, in a letter dated 19
August 1980, suggested that consultants' forecasts may be too high as a
result of recent decline and anticipated future decline of activity in the
commercial salmon fishing industry and as a result of predicted stabiliza-
tion of timber production through the year 2020. These concerns are valid;
however, the load projections for the fishing and lumbering industries are
expected to double by 1990 due to changes in processing equipment that are
electric energy intensive. In addition, woodwaste products, including
sawdust, could conceivably be used in the production of ethanol, methanol,
and pressed board that would require electric energy.
A low growth scenario was studied, based upon the economic constraint of
continued production of electric energy by high cost diesel machines. In
this case, it was assumed that the high cost of electric energy would
discourage the modernization and expansion of industrial and commercial
loads. With this scenario, in the year 2000 Petersburg and Wrangell would
have to purchase 17,930 kW of new diesel units to replace 11,680 kW in
units scheduled for retirement, plus 6,750 kW to meet new load. Even with
the low growth case, Tyee Lake power will be economically feasible.
Table 2 compares the estimated annual energy requirements of the
Petersburg/Wrange 11 load center with the combi ned, potent i a 1 generating
capacity of the existing Petersburg hydropower project and the proposed
Tyee Lake project. The addition of the Tyee Lake project will provide
sufficient energy to these two load centers, even with discontinued use of
existing diesel generation, to beyond the year 2000.
22
Table 2
Estimated Energy Requirements for Petersburg/Wrangell
Compared with Potential Hydropower Generation Capacity
Year
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Petersburg/Wrangell
Energy Requirements
(MWh)
47,490
50,650
53,920
57,470
61,350
65,540
70,030
73,060
76,220
79,530
82,960
86,560
90,050
93,960
97,450
101,380
105,470
Petersburg Hydro
Get1eration
(M\~h )
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
9,755
1/ Stage 1 on line with 20,000 kW. 1/ 10,OOO-kW unit added.
Tyee Lake
Estimated Average
Generation Potential
(MWh)
86,667 1/
86,667
86,667
86,667
86,667
86,667
86,667
86,667
86,667
86,667
86,667
86,667
130,000 1./
130,000
130,000
Generating Capacity,
Potential Surplus
(Without Diesel)
(MWh)
42,502
38,952
35,072
30,882
26,392
23,362
20,202
16,892
13,462
9,862
6,372
2,462
42,305
38,375
34,285
Source: Federal Energy Regulatory Commission and International Engineering Company,
Inc., 1980.
23
Conclusions
The capacity of the Tyee project will meet the forecast peak demand of the
Petersburg/Wrangell service area for the foreseeable future. The ultimate
30,000 kW of installed capacity and 130,000 MWh of average annual energy of
the Tyee Lake project will be sufficient to satisfy the area's needs beyond
the year 2000. Cor.struction of this project eliminates the need for
Federal action at this time.
24
~,
KETCHIKAN/METLAKATLA AREA
The Ketchikan/Metlakatla study area includes the Ketchikan Gateway Borough,
Prince of Wales and Annette Islands, and, potentially, the U.S. Borax
Company mining development on the mainland (Figure 8).
The Ketchikan Gateway Borough encompasses Revillagigedo, Gravina, and a
host of smaller islands in the Southeast Alaska archipelago. The City of
Ketchikan and immediate area are considered as one load center within the
Gateway Borough. The service area of Ketchikan is confined to the vicinity
of Tongass Narrows in the southwest corner of Revillagigedo Island. Access
to this relatively small fraction of the borough is entirely by air or sea.
The village of Metlakatla is approximately 17 miles south of Ketchikan on
Annette Island and is outside of the Gateway Borough. The Metlakatla load
renter is not intertied with Ketchikan.
The U.S. Borax Company mining development, a potential world class
molybdenum mine, on the Alaskan mainland is approximately 43 miles east of
Ketchikan and Metlakatla. The energy requirements of this load center are
addressed only as they may impact the City of Ketchikan.
The entire region is part of the Tongass National Forest, with the
exceptions of townsites and the Annette Island Indian Keserve, and is
subject to certain withdrawals for native communities under the terms of
the Alaska Native Claims Settlement Act.
Geologically, the islands of southeastern Alaska are, in effect, a drowned
mountain range. The land rises precipitously from deep fjords to mountain
uplands with peaks to over 4,000 feet. The adjacent mainland is similar,
with peaks to over 14,000 feet, permanent ice fields and valley glaciers,
and few areas of level or near level land. Lakes are typically perched in
narrow glaciated valleys with steep walls. Bedrock, except in the valley
bottoms, is seldom more than a few feet below the ground surface and is
often exposed. The terrain, to an elevation of about 2,700 feet, has a
dense cover of rain forest and lush undergrowth. The steep slopes continue
below the waterline to form inlets often over 100 fathoms.
METLAKATA
Study Area
Annette Island is located near the southern end of the Alexander
Archipelago. The island covers 136 square miles, but because of
mountainous terrain, settlements are limited to the approximately
24-square-mile Metlakatla Peninsula. The town of Metlakatla is located at
the north end of the peninsula and is accessible only by air or water. The
closest residential and commercial center is Ketchikan.
Population and Economic Characteristics
Metlakatla is the second largest community in the Ketchikan/Metlakatla area
and is the predominant population center of the Outer Ketchikan census
division. The remalnlng population of the area is found in smaller
communities on Prince of Wales Island, Annette Island, and the mainland.
25
REVILLAG/GEDO ISLAND
I\)
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The town of Metlakatla was founded by the Tsimshian Indians on 25 March
1887. Since then, they have been joined by other Alaskan Natives and by
Caucasians. In 1891, the U.S. Congress created the Annette Islands
Reserve, which set aside for the exclusive use by "Metlakatla Indians and
othe Natives of Alaska" the entire Annette Island. In 1980, the population
was about 1,100 and was still predominantly Alaska Natives.
Three sc£narios of population projections are presented in Table 3. These
growth scenarios (low, most likely, and high) reflect different assumptions
about future economic activities and the community's decisions on
immigration. Under the most likely scenario, the population will increase
from 1,100 in 1980 to 1,240 in 1990 and 1,400 in 2000. This scenario
corresponds to a continuation of the present annual population growth rate
of 1.2 percent. The low scenario reflects a continuation of depressed
lumber markets and no new industries. The high forecast assumes a rapid
development of forest products and fisheries industries, new small business
ventures, and development of the buildings at the Annette airport for
commercial use.
Table 3
Annette Island Population Projections 1/
Year Low Most Likel,l ~
1985 1, 140 1,160 1,200
1990 1,200 1,240 1,300
2000 1,300 1,400 1,500
1/ Year-round residents.
Source: "Chester Lake Project Feasibility Report," Harza Engineering
Company, May 1982.
Fishing and logging are the major income producting activities on the
island. The Metlakatla Indian Community owns, operates, and leases these
income producing enterprises. Because of the seasonal nature of some
activities, the employment rate falls in winter and peaks in summer. The
work force varied between 349 and 753 with and average of 511 during 1977.
Other employment includes 15 people in construction, 50 in transportation,
which is mostly associated with the timber industry, 20 in the Federal
government, 80 in local government, and 30 in the school district.
Economic growth is expected to continue and to bring greater job stability
in the near future. The community is proceeding with several enhancement
efforts to counter the large natural fluctuations in salmon runs from year
to year and to avoid the swings in seasonal employment. New equipment at
the sawmill is expected to increase employment as much as 40 percent and
new processing activities could lower local housing construction costs and
spur increased construction employment. A new harbor has been constructed
to aid the fishing industry and new housing and public facilities are
planned or under construction. Surveys of mineral resources reveal a
potentially valuable deposit of barite and deposits of silver, lead, and
zinc.
27
Existing Power Generating Resources
The electric utility, Metlakatla Power and Light, operates two generating
plants. The Purple Lake hydroelectric plant has three 1,000-kW units and
the Quarry Plant has two 1,500-kW diesel driven generators, one insta1ied
in 1967 and the second in 1970. The diesel units meet the large power
fluctuations of th2 sawmill operations and supplement the hydropower plant.
The sawmill has four stand-by diesel units (900, 750, 450, and 350 kW) that
are used during repairs or maintenance at the quarry plant. These diesel
units have provided only 5 percent of the sawmi11 1 s electricity demand and
are not interconnected to the is1and 's distribution system.
Potential Power Generating Resources
The 1982 "Chester Lake Project F eas i bil ity Report," comp 1 etecl for the
Alaska Power Authority and Metlakatla Power and Light, identifies several
alternative means for meeting future electrical power demands: the Chester
Lake project, Purple Lake alternative, Triangle Lake alternative, woodwaste
generation alternative, and diesel generation alternative. Metlakatla
public meeting results and further investigation of potential
configurations of the Chester Lake project are contained in an Alaska Power
Authority draft report not yet published at the time of this Southeast
Hydropower Interim report. The following information on the Chester Lake
project reflects both reports.
Chester Lake Hydropower Project: The 1982 "Chester Lake Project
Feasibility Report" identified three alternative project plans for Chester
Lake that are all generally similar. These plans consist of a concrete dam
downstream of the existing water supply dam, a steel surface penstock, and
a sea level powerhouse with a single generating unit. The three
alternatives vary in reservoir storage capacity and installed capacity as
follows:
Reservoir
Surface Usable Storage Capacity
Alternative Elevation (ae re-f eet) (kW)
1 885 4,180 2,500
2 845 0 2,500
3 845 0 1,500
Alternative 3 was considered to be part of a combined development involving
a 1,000-kW expansion of the Purple Lake project.
On page 6 of the Chester Lake report, the first alternative was
recommended, IIbased on the results of economic analysis, which show this
configuration of the Chester Lake project to have the least present worth
cost under the most likely scenario of load growth." This project would
have an 80-foot high concrete arch-gravity dam built across Waterfall Creek
at the outlet of Chester Lake. The dam would raise the existing lake level
40 feet and create a reservoir with 4,180 acre-feet of storage. A
28-inch-diameter, 2,800-foot-long penstock would conduct water from the dam
to the powerhouse. The powerhouse would be a reinforced concrete structure
28
containing one Frances type turbine generator unit with a
2,500 kW, an average flow of 22 cfs, and a rated net head
project would generate an average of 10,300 MWh per year.
generation would be 7,900 MWh.
rating of
of 800 feet.
Firm energy
The
Alternatives 2 and 3 would be a run-of-the-river project with a lower dam,
instead ~f a storage project, which would involve a higher dam. A
run-of-the-river project would have an average annual generation of
9,800 MWh and a firm annual generation of 6,600 MWh.
Metlakatla Indian Community has indicated a preference for construction of
the higher dam storage alternative, although the Alaska Power Authority
recommended the lower dam run-of-the-river alternative based on potential
financial risk and joint operating characteristics with the Purple Lake
hydroplant. One of Metlakatla's concerns is that the run-of-the-river
project leave sufficient water storage for the community water supply. The
Alaska Power Authority believes this stipulation can be met.
Another key issue is that there is a large amount of electric space heating
in the market area that can be expected to be more sensitive to rate
increases than other electrical energy end uses. This is a concern in
trying to balance the project cost, kilowatt per hour cost, and expected
market reactions to higher costs. These are considerations of the Alaska
Power Authority for selection of a run-of-the-river project over a more
expensive storage project with more firm energy.
Purple Lake Alternative: This alternative would make modifications to the
existing Purple Lake project to increase the project's capacity and energy
production. Installation of a fourth unit at Purple Lake (1,000 kW) in
combination with a 1,500-kW Chester Lake development was the most viable
alternative of those studied for Purple Lake. However, studies reveal that
the existing Purple Lake project already has the capability to utilize
nearly all of the available runoff.
Triangle Lake Alternative: This project would be located in northeastern
Annette Island and would develop the head between Triangle Lake and Hassler
Harbor. The project would consist of a dam, a l-mile-long penstock, a sea
level powerhouse, and a 12-mile transmission line. The installed capacity
of the project would be 3,000 kW, with an estimated average annual energy
output of 11,000 MWh.
Woodwaste Generation Alternative: Woodwaste generation was considered for
electrical power by use of waste material from the Annette Island sawmill.
However, the woodwaste is already being used for fuel in a Ketchikan
facility. Also, the sawmill operations are intermittent and may not
provide a reliable source of fuel for power generation.
Diesel Generation Alternative: This alternative consists of continued use
of the two existing 1,500-kW diesel generators at the quarry diesel plant.
The diesel units would be replaced with new units after 20 years of
service, with additional diesel capacity added as required to meet
increasing demands.
29
Demand for Electricity
Historical data on annual energy generation for 1975 to 1980 are presented
in Table 4. During that period, the Purple lake hydropower project
generated an average annual energy of 13,773 MWh. Annual variations in
hydropower generation were related to precipitation variations on the
island. The diesel plant provided the additional energy requirements that
varied between 1,433 to 3,472 MWh. In general, generation requirements are
about 30 percent greater in winter than in summer with peak demands also
occuring in winter.
Three projections of future electrical energy demand were developed based
on current use and the Harza Engineering Company alternatives. The most
likely scenario assumes a continuation of present activities and includes
the realization of projects under design and being planned by the
community. The low scenario reflects a more conservative growth, with some
planned development delayed. The high scenario assumes fuel operation and
expansion of the existing industries, installation of new business, and
development of the buildings at the Annette airport for commercial use.
Table 4
r~et 1 akat 1 a Area Historical Peak and Energy Demand
Total Energy Generation 1/
(MvJh) 1975 "1976 1977 1978 1979 1980
Hydropower Plant 14,912 14,273 13,095 12,714 12,653 14,994
Diesel Plant 2,514 1,433 3,472 2,798 3,227 2,694
Tota 1 17,426 15,706 16,567 15,512 15,880 17,688
Peak Demand (kW) 5,280 4,440 4,470 4,000 4,600 4,770
load Factor (% ) 37.7 40.0 42.3 44.3 39.4 42.3
1/ Includes station service.
Source: Metlakatla Power and light; REA Form 7, REA Form l2e.
The energy demand forecasts are given in Table 5. The annual energy demand
is expected to increase from 15,200 MWh in 1980 to 23,400 MWh in 2000 under
the most likely scenario. The energy demand would be 26,800 MWh under the
high scenario and 19, 100 MWh under the low scenario.
30
Table 5
Metlakatla Area E 1 ectri ca 1 Energy Forecast
Low l"1ost Like ly ~
Generation Peak Generation Peak Generation Peak
Demand Demand Demand
Year ( GWh) (MW) (GWh) (MW) (GWh) (MW)
1980 18,000 4,700 18,000 4,770 18,000 4,770
(Historic)
1985 19,850 5,040 22,010 5,580 24,060 6, 100
1990 20,210 5,130 23,410 5,940 26,140 6,630
2000 21,920 5,560 26,880 6,820 30,840 7,820
Source: "Chester Lake Project Feasibility Report," Harza Engineering
Company, May 1982.
Comparison of Demand and Resources
Uf the alternatives considered to increase the generating capacity of the
Meltakatla area, the Chester Lake project alternatives are considered the
most feasible. The Triangle Lake project is the second most preferred
alternati ve.
The power market forecasts in comparison to existing and proposed
generating capability are shown in Figure 9. The addition of the Chester
Lake hydroelectric project in 1986 would displace the existing use of
diesel, except for meeting peak loads, until 1990 under the most likely
growth scenario. At that time other potential hydropower alternatives such
as Triangle Lake may need to be developed to meet increasing demands.
Conclusions
A hydroelectric project at Chester Lake has been identified as the most
feasible addition to the existing electrical generating facilities for the
Metlakatla service area. Of the alternative options for Chester Lake, the
community has indicated a preference for a storage project. The Alaska
Power Authority recommendes a run-of-the-river project and is preparing the
detailed findings and recommendations and is expected to publish their
recommendation in mid-1983.
The community has received a licensing exemption from the Federal Energy
Regulatory Commission (FERC) and has received a Corps of Engineers 404
permit to construct a project at Chester Lake. The Rural Electrification
Administration (REA) has authorized a $5,480,000 loan for the project. The
1983 Alaska Legislature is considering HB232 to authorize the Chester Lake
project at $13.2 million.
31
.-" .--'" '-.---
/":-. .. -/"
/"
./". ;,..;... ---
--.. .--. ..-..;.~ .-.. --r'" ' " , :-HIGH CASE _.-.-:-. . . . . .'
-.-~~: "'.' ..
. MiDlUji CAl; .:.-. ..;...; ...:.--..;.... .'';'---DIESEL IIIM* ~:,.~ "."
CASE
35
30
25
......
.&: ./. ....... LOW
/" ---. ~.
..L.."-' ..
20~ -. CHESTER LAKE
......
Q
Z
"" DIESEL 16~
r
1980 1985
PURPLE LAKE
.
1990
YEARS
J .
1995
•
10
5
o
2000
~--------------------------------------------------------~IO
9
8
DIESEL· . CHESTER LAKE
~----------~~------------------------------------------~3
2
PURPLE LAKE
~~ __ L--L __ L--r __ ~-L __ L-_L-'4-~ __ ~' __ ~~~ __ +-_~'_~'-L __ ~-+0
1980 1985 1990 1996 2000
YEARS
Figure 9. Metlakatla power market forecast.
SOURCE: Harza En ineering Co.-February 1982
Q
A Chester Lake project could be completed in 1986. In the early 1990's,
increasing electrical demand is expected to exceed the existing hydropower
capacity and the Chester Lake addition. There are other viable
alternatives to diesel generation, such as the Triangle Lake hydroelectic,
project that could be considered at that time.
It appea~s that the Alaska power Authority will continue with these
evaluations in the n~ar future. If they do not proceed with further
studies, additional study by the Corps of Engineers may be warranted.
KETCHIKAN
Study Area
Ketchikan and the potential hydropower sites lie on Revillagigedo Island, a
roughly oval, deeply fjord incised island about 55 miles long by 33 miles
wide near the southern end of the region. The highest point of the island
is 4,560 feet, while the basins of the hydropower sites are divided by
3,000-foot-high peaks.
This area (Figure 10) lies within the maritime climatic zone and has
generally moderate temperatures, abundant precipitation, little sunshine,
and frequent storms. The mountainous topography of the region has a strong
local influence on weather and results in great changes in precipitation
and temperatures within short distances as well as channelized wind
patterns. Climatic records at the City of Ketchikan, which is near sea
level, show a mean annual temperture of 46°F with extremes of +96°F and
-8°F. Average annual precipitation for the City of Ketchikan is 154
inches, including an average of almost 33 inches of snowfall. This is
contrasted with a typical annual precipitation of 250 inches at elevations
above the city where hydropower sites are being considered.
Population and Economic Characteristics
Population
The 1981 estimated population of the study area, which encompasses the
Ketchikan, Outer Ketchikan, and Prince of Wales census divisions, was
15,220. Approximately 11,373 persons live in the Ketchikan Gateway
Borough, with about 7,200 of these residing in the Ketchikan metropolitan
area.
The City of Ketchikan was founded in 1882 and, except for population surges
due to gold rush activity and pulp mill construction, has experienced a
slow but steady growth. Population data are presented in Table 6.
33
'" 0 c ....
:I: m ." "'e: .... m
:I:~ -< c· :a Z
0 0
m :I r-.
m" Om
.... 0
:a"
-II> 0
"i o· :IE ....
m· II>
:a" • Z .... m :a
I:
~
G
~ c:: ...
0 •
" m
-4
0
:I:
" ,.
Z
CJ)
-4
C
~ ,.
:XJ m ,.
5 0 we Me ..
10 15 20
STATIITE MILES
5 10 20
KILOMETER SCALE I: 250,000
Table 6
Ketchikan Study Area Population
Outer Prince Total
Year Ketchikan Ketchikan of Wales Stud~ Area
1900 770 620 780 2,170
1909 1,687 708 945 3,520
1920 3,025 1,457 1, 188 5,670
1929 4,429 1,134 1,218 6,781
1939 5,742 912 1,572 8,226
1950 6,829 1,256 1,400 9,485
1960 8,774 1,296 1,772 11,842
1970 10,041 1,676 2,106 13,823
1980 11 ,316 1,333 2,489 15, 138
Before 1960, changes in population levels were related primarily to fishing
and fish processing, while the dominant economic forces since 1960 have
been the cross currents of a declining fishing and processing industry
offset by an expanding forest products industry.
Economy
The principle commodity producing industries in the Ketchikan area have been
and continue to be associated with products from the sea and forests, while
the government and the tourist industry are the major noncommodity producing
employers.
Fisheries: Ketchikan dates from 1882 when a salmon saltery was established
at the mouth of Ketchikan Creek. Growth, at times influenced by nonlocal
events such as the gold rush at the turn of the century, World War I, and
World War II, was mainly associated with an ever expanding fishing industry,
mainly salmon, until the early 1960's when a major forest products industry
developed. Fishing, though greatly diversified now, has decreased in the
last decade, primarily because of a dramatic decline in salmon stocks due
to overfishing. However, with sound management this trend may be at least
partially reversible. Table 7 shows the fishery production for the
Ketchikan area for the latest years of record. Growth potential in the
harvest exists mainly in herring and bottomfish species, which have been
underutilized by the American fishing industry.
35
Table 7
Ketchikan Area Fisheries Harvest
(1,000 lbs)
Year Salmon Other Fin Shellfish Tota 1
1972 37,222 3,263 39 40,524
1973 23,876 8,945 12 32,833
1974 27,791 8,975 33 36,799
1975 15,217 5.,822 68 21,107
1976 28,006 8,632 45 36,683
1977 50,366 5,407 45 55,818
1978 65, 118 2,745 192 68,055
1979 26,338 2,618 0 28,956
1980 28,303 1,684 201 30,189
Source: Alaska Department of Fish and Game, Division of Commercial
Fisheries.
Forestry: Wood products manufacturers, mainly wood pulp, are the largest
commodity producing employers in the study area. Table 8 shows wood
product production for selected years for the study area. Potential exists
for expanded harvest and processing, but because of economic factors and
competing land uses, the long term outlook is for a sustained level of
activity not too different from the present level, except for market
induced fluctuations.
Table 8
Ketchikan Area Wood Products
(millions of board feet)
Year Lumber Pulp Total
1972 150 169 319
1973 161 181 342
1974 150 168 318
1975 102 114 216
1976 125 140 265
1977 132 148 280
·1978 133 89 222
1979 123 83 206
1980 152 102 254
1981(pre1iminary) 108 73 181
Source: Alaska Department of Natural Resources.
36
..-
....."',
;~jIi;~
Mining: Although mining to date has involved many different minerals in
the study area, no large or long term industry has developed. However, in
the past 10 years, significant exploration has been conducted in the area
and a major mine, mill, and concentration operation for molybdenum is
projected for the immediate future. The Quartz Hill Mine, owned by U.S.
Borax, is about 43 miles from Ketchikan. With an estimated employment of
about 1,000, this operation could be a large utilizer of both labor and
services within the study area.
Government: The single largest employment sector in the study area is the
government, mainly the State but with some Federal and local positions.
Most of the State jobs are connected with the Alaska Marine Highway
System. Projections are for continued expansion in the ferry system over
the next several years; thus, there is a potential for increased employment
in this sector. Federal employment experienced an abrupt recession in 1976
with the moving of the Annette Island U.S. Coast Guard operations to
Sitka. A steady growth in local government parallel to projected
population growth is expected.
Tourism: The Ketchikan tourist industry is relatively undeveloped compared
to other areas within southeastern Alaska, primarily because of the
region's climatic conditions and lack of visitor facilities. The community
is involved in expanding tourism, which is regarded as a major economic
contributor for the future.
Commerce: Ketchikan is one of the major seaports of Alaska in terms of
annual cargo tonnages. In addition to the coastwise movement of logs and
the import and export of supplies and products related to the wood pulp
industry, the port is a supply and distribution center for the southern half
of southeastern Alaska and the home port for the Alaska Marine Highway
ferries. Tables 9 and 10 show cargo movement at the port during recent
years.
37
Table 9
Port of Ketchikan Waterborne Commerce
(1,000 tons)
Year Rafted Logs Other Freight Total
1970 902 966 1,868
1971 769 838 1,607
1972 1,218 968 2,186
1973 1,091 1,076 2,167
1974 1,208 954 2, 163
1975 710 853 1,563
1976 636 923 1,559
1977 827 1, 139 1,966
1978 679 1,293 1,972
1979 501 1 ,701 2,202
1980 872 1,895 2,767
1981 424 1,455 1,879
Source: "Waterborne Commerce of United States, Part 4, Waterways and
Harbors, Pacific Coast, Alaska and Hawaii," Corps of Engineers, Fort
Belvoir, Virginia.
Table 10
1981 Ketchikan Waterborne Commerce
Category
Rafted Logs
Fue 1 Oil
Lumber
Pulp
Chips
Gasoline
Logs
Groceries and Commodities
Other (mach., fish, autos,
sand and gravel, misc.)
Tons (1000)
424
253
201
132
161
98
181
18
411
Source: "Waterborne Commerce of United States, Part 4, Waterways and
Harbors, Pacific Coast, Alaska and Hawaii," Corps of Engineers, Fort
. Belvoir, Virginia.
38
Employment
The seasonality of employment in the study area results for the most part
from the high levels of employment in fishing and fish processing, and in
associated distributive industry and government employment during the peak
salmon fishing months of the summer. Tourism is also a factor in increased
summer employment, while the virtual cessation of logging activity in
midwinter further compounds the fluctuation.
In 1982, the Ketchikan area experienced a peak unemployment rate of 15.7
percent in March, while 6.1 percent of the work force was recorded as being
unemployed during September, the lowest rate month. The average annual
unemployment rate was 12 percent.
Table 11 summarizes 1980 Ketchikan area employment by industrial
classification. Uniformed military and some self-employed and part-time
workers (primarily fishermen) are not included.
Tab le 11
Ketchikan Area Employment, 1980
Tot a 1 Emp 1 oyment
Mining
Contract Construction
Manuf acturi ng
Transportation, Communications, Utilities
Wholesale and Retail Trade
Finance, Insurance, Real Estate
Services
Government
Source: Alaska Department of Labor
Natural Resources
Fish
6,732
4
430
2,061
655
1,000
239
890
1,453
All five species of Pacific salmon are harvested in the Ketchikan area, as
are halibut, various shellfish, and herring eggs. Among the more familiar
species, especially salmon, halibut, shrimp, and crab, the resources are
being harvested to or near their full maximum sustainable yields. Only in
the low unit value species such as herring and bottomfish is there any
significant potential for increased harvest.
39
Wildlife
Southeastern Alaska has a variety of wildlife ranging from huge whales to
tiny shrews. Some, as in the case of brown bear and moose, have severely
limited distribution, while others, such as Sitka deer and waterfowl, are
found almost everywhere. Revillagigedo Island has populations of black
bear, Sitka deer, w0lf, mink, marten, wolverine, many varieties of small
rodents, numerous varieties of gulls and seabirds, and bald and golden
eagles. The area 1S visited by migratory waterfowl ranging from the common
ducks to the trumpeter swan. Sea mammals include several varieties of
whale, porpoise, and the more common varieties of seal.
The watersheds of the various ~erched lakes considered in this study have
wildlife populations of the common terrestrial species but are outside the
range of the sea mammals. The endangered American ~eregrine falcon is not
known to reside in any of the watersheds, but may migrate through the area
under study. The bald eagle, endangered in other states, may be expected
to nest within any of the project watersheds and/or possible transmission
corridors. Many varieties of songbirds are scattered throughout the island
and may be found almost anywhere. Ptarmigan are plentiful and can be found
on the upper peaks and meadows of the island, while grouse, though not
common, may occasionally occur below the treeline. Migratory waterfowl may
make incidental use of some of the lakes, but are not known to utilize any
of them in significant numbers.
Minerals
Over 40 mines have operated at various times in the vicinity of Ketchikan.
Copper, gold, silver, palladium, lead, zinc, and uranium metals have all
been produced commercially. Ueposits of iron, antimony, molybdenum,
beryllium, chromite, and rare earths have been investigated for possible
production. Nickel, cobalt, bismuth, and tungsten are also known to be
present, but the quantities and concentrations are unknown. Energy related
mineral deposits such as coal and petroleum are almost nonexistent in the
Ketchikan and southeastern Alaska areas.
Forests
The coastal western hemlock-Sitka spruce forests extend from tidwater to the
treeline over the islands and mainland around Ketchikan. The entire region
is part of the Tongass National Forest. The Ketchikan portion of the
Tongass has an estimated allowable annual cut total of 509 million board
feet (mbf) of which 294 mbf is classified accessible with the remaining 215
mbf considered inaccessible. With full management, it is estimated that
the sustained yield capacity could be raised from 509 to 966 mbf, an
increase of almost 90 percent. While this i~ unlikely to be totally
accomplished because of conflicting alternative land use needs, a lesser
increase in the sustained yield capability is possible. Full allowable
harvest, on present reserves, would involve about 30,000 acres annually.
40
Recreation
Southeastern Alaska is a recreational paradox. While the mountains,
forests, fjords, glaciers, and waterways offer scenic beauty of great
variety and splendor, the low clouds, rain, general lack of sunshine, and
frequent storms conspire to make the scenery indistinct or invisible much
of the time. The potential for sport fishing, hunting, hiking, and camping
is high in terms of available resources, but these activities can often be
limited by the weather.
Demand for Electricity
Hi storica 1 Use
Electrical power demand at Ketchikan has increased steadily through the
last 50 years. Since 1933, energy demand has, on the average, increased
5.7 percent annually, and peak power demand has increased 5.3 percent
annually. Rates of growth in recent years have been lower. Energy growth
since 1965 has been 3.8 percent, and from 1975 to 1981, 3.4 percent. The
lower rates since 1975 reflect conservation measures and slower economic
growth due to increased fuel costs and less heating demands during several
mild winters. Since 1981 t there has been a rapid increase in demand due
generally to a shift to electric heat because of increased fuel oil costs
and the projected competitive cost of power as Swan Lake comes on line. An
historic power summary is given in Table 12.
Table 12
Ketchikan Area Historical Generation and Peak Loads
Net Energy 1/ Peak Load Load Energy
Year (GWh) -(MW) Factor (%) Growth (%)
1933 6.2 1.5 48
1935 6.8 1.7 45 4.7
1940 14. 1 3.0 53 4.9
1945 16.9 3.2 60 15.7
1950 22.4 4.7 55 3.7
1955 32.4 7.1 52 5.8
1960 37.9 7.8 54 7.7
1965 47.9 10. 1 54 3.2
1970 61.8 11.8 59 4.8
1975 69.2 13.0 63 5.2
1980 86.0 17.7 58 2.3
1981 87.5 16.9 63 4.4
Average Energy Increase: 1933-1981 5.7%
1965-1981 3.8%
1975-1981 3.4%
1/ Does not include Louisiana Pacific Pulp Company, Ketchikan Division
lnterchange.
41
Projected Demand
Ketchikan area power requirements were estimated through year 2000 by the
Alaska Power Administration. Estimated power requirements for the three
levels of load conditions are shown in Figure 11. The "low case" is the
continued normal pcwer use growth with a population increase at the long
term average of 2 percent annu~lly. Energy use was estimated at 10,280 kWh
per customer for residential customers after 1982. No major change to
electrical heating systems was considered. Economic conditions were
considered to continue to increase at a slow rate with stable timber and
fishing industries. The relative distribution of power by sector would
remain constant at these hfstoric percentages:
Residential 52%
Commerc i a 1 39%
Industrial 2%
Other 2%
The "medium case" is the continued normal power use growth of the low case
plus the addition of electric heat. About 35 percent of existing
(pre-1980) residences are expected to convert to electric heat by 2000 as
electrical heating becomes competitive with oil heat. New residences using
electric heat would increase to 90 percent by 1985 (in 1981 and 1982
between 70 and 90 percent of new residential customers used electric heat
in anticipation of competitively priced electrical energy from Swan Lake).
Electrical heat residential customers are estimated to use 22,880 kWh per
year total. The addition of commercial electric heat is estimated at 15
percent of the total residential heat. The medium case is considered the
most likely set of conditions governing growth and is used as the base for
analysis in this study.
The "high case" is the medium case plus the addition of U.S. Borax
Corporation employees and support services to Ketchikan. This includes .200
of the 1,000 construction employees from 1984 through 1986, plus 200 support
employees for community services as food and retail businesses, education,
transportation, etc.~ and 860 permanent operating employees, plus an equal
number of community support service people.
Future power requirement estimates are summarized in Table 13. In summary,
the low case energy estimate increases at an annual rate of 2.4 percent
from 1982 to 2000 .. The medium and high estimates increase 4.2 and 5.6
percent respectively. Peak demand increases correspondingly by 3.7, 6.4,
and 7.9 percent annually. Details of each load case and a comparison with
previous estimates are given in Appendix F.
42
,-------------------------------------------------------------------T300
HISTORIC AND ESTIMATED ENERGY DEMAND
LEGEND
-----------HIGH CASE
-.-._.-.-.-.-.-MEDIUM CASE (SELECTEDI
---------LOW CASE
APA-REVISED
12/15/82
HISTORICAL
I ,
I ,
I , ,
I
I
ESTIMATED
280
260
240
220
200
180
~
160C
140 i c a
120 I!l
100
80
60
40
20
.-------------------------------------------------------------------~·71
194~
HISTORIC AND ESTll'ATED PEAK CAPACITY
1950
LEGEND
------------HIGH CASE
._.-._._._._.-MEDIUM CASE (SELECTEDI
------LOW CASE
19151S
APA-REVISED
12/15/82
HISTORICAL
INO IMIS 1.70 1971S
YEARS
INO
ESTIMATED
!SI81S 1 .. 0
Figure 11. Historical and estimated power demand, Ketchikan.
61S
60
lSI
20
10
, .. IS
Table 13
Ketchikan Area El ectric Load Est imates
Low Medium ~
Net Peak Net Peak Net Peak
Generation Demand Generation Demand Generation Demand
Year (GWh) . (MW) . (GWh) (MW) (GWh) (MW) .
1982 105.7 24. 1 105.7 24. 1 105.7 24."1-
1983 107.7 24.6 112.3 26.3 112.3 26.3
1984 109.8 25. 1 117.0 27.8 130.4 31. 6
1985 111. 9 25.5 122. 1 29.4 134.9 33.0
1986 114. 1 26.0 126.9 30.9 140.0 34.6
1987 116.2 26.5 131.8 32.5 161 .0 40.8
1988 118.4 27.0 137.0 34. 1 181 . 7 47.0
1989 120.5 27.5 142.0 35.7 202.7 53.2
1990 122.5 28.0 146.9 37.3 207.3 54.7
1995 134.0 30.6 173.8 45.7 234.0 63. 1
2000 146.5 33.4 202.5 54.8 262.7 72. 1
Source: Alaska Power Administration, December 1982.
44
Existing Power Generating Resources
EXisting utility systems within the load center are the responsibility of
the Ketchikan Public Utilities (KPU). The electric division of KPU serves
virtually all the service area's demand with the exception of the Ketchikan
Pulp Company. The KPU facilities consist of hydroelectric and diesel
generation. Table 14 shows the average annual generation of each plant
from 1970 through 1980.
Table 14
Ketchi kan Area Average Annual Generation by Plant, 1970-1980
Installed Dependable Average
Capacity Capac ity Net Energy Percent
(kW) (kW) (kWh/~ear ) of Energ~
Diesel
Totem Bight 2,000 2,000 1, 100,000 1.4%
Southwest Baily 15,450 14,450 11,917,000 15.5
Ketchikan Lakes .lI 900 870 115,000 o. 1
Subtota 1 18,350 17,320 13,133,000 17. 1
Hydroelectric
Beaver Fall s 21 6,000 4,750 36,586,000 47.5
Ketchi kan Lakes 11 4,200 1,800 16,903,000 21. 9
Sil vi sLake 1/ 2, 100 2,000 10,400,000 13.5
Subtota 1 12,300 8,550 63,889,000 82.9
Total (period of record) 30,650 25,870 77,022,000 100.0%
Total (at end of
period of record) 28,750 25,000
11 Discontinued in 1979. The 0.1 percent of the total average annual
generation that was produced by the Ketchikan Lakes units is now
carried by the remaining system.
II A 1,000 kW-unit was removed from service in 1971 due to lack of water.
31 Capability reduced during winter low flow period. !I 1976 through 1980 only.
The l,OOO-kW unit that is recorded as removed from service at the Beaver
Falls hydroelectric plant did not account for any recorded energy
generation. This unit is one of two that are supplied by a secondary
penstock with a run-of-the-river inlet. The supplying stream does not have
sufficient flow to operate both units.
The total installed capacity of the KPU system is now 28,750 kW. The total
dependable capacity of this system is 25,000 kW, of which 16,450 kW (65.8
percent) are diesel and 8,550 kW (34.2 percent) are hydroelectric.
45
Two timber industries, Louisiana Pacific Pulp Company, Ketchikan Division,
and Ketchikan Spruce Mill, each have their own generation as part of their
manufacturing process. Louisiana Pacific has a steam electric generation
installed capacity of 38,600 kW and produces 150 million kWh annually.
Louisiana Pacific is interconnected to the KPU transmission system but is
limited to 2,000 kW. Both KPU and Louisiana Pacific Pulp Company provide
each other with limited amounts of energy on demand but, in general,
Louisiana Pacific provides energy to KPU in exchange for energy that KPU
then supplies to Ketchikan Spruce Mills, which is also owned by Louisiana
Pacific but is located in the center of Ketchikan. Because Louisiana
Pacific uses almost all of its energy and capacity and the interchange
agreement is for rather small amounts of energy, the Louisiana Pacific
generation is not included in this project analysis.
Planned Power Generating Resources
In anticipation of growing energy demand that will exceed its generating
resources, the City of Ketchikan determined that the Swan Lake project,
identified in the early stages of this study, was the most favorable
project for development. Ketchikan submitted a FERC license application
for the Swan Lake project in February 1979, which was identified as Swan
Lake project No. 2911. The Alaska State Legislature appropriated funds to
be administered by the Alaska Power Authority towards construction of the
Swan Lake project. Design and construction are currently under way and
initial power production is scheduled for mid-1984.
The Swan Lake project is on Falls Creek and Swan Lake, about 22 miles
northeast of Ketchikan. The project would have an installed capacity of
22,000 kW and dependable capacity of 18,000 kW. Estimated average annual
energy is 85,400,000 kWh.
Comparison of Uemand and Recources
Figure 12 compares the existing generating capabilities of Ketchikan with
its expected electrical demands. Firm energy capabilities of all
hydropower would momentarily meet demand when Swan Lake comes on line in
1984, with the system immediately using secondary energy, when available.
By 1991, existing diesel units would be required to meet energy demand.
The addition of Swan Lake capacity would still not meet the estimated
capacity demand without continued use of diesel. By 1994, new diesel
capacity would be required to meet increasing demand. Also, by the
mid-1990's, several existing diesel units would need replacement.
Planning Objectvies
The study objectives are derived from the problems and needs that are
specific to the study area and that can be reasonably addressed within the
framework of the study authority and purpose. The planning objectives for
this study are:
. to reduce the cost of electricity and to meet the intermediate and
long term electrical energy needs of the Ketchikan area,
46
22
200
180
:c
~ 120
>-= 100 I ...
80
40
20
.. .......... ........ ......... " ..•....•. ..........
-........... . ...••...•..•. .............
;:t>fESEL.::: ..•.••.•...•
1880 19811
... -t:::::: """ ........ . .,,-.:::::::::: ::
ESTIMATED ENERGY DEMAND ...............• •....•••.•••..•.•. •................... .......................
'-__ .. .r ••• ::::::::::::::::::::::::: .................•.•........• ....••••.•....••••.•...•.•.•.... •••.••.••.•..•.•....••.••.•.....•. .....................................
••• EXISTING DIESEL ENERGY::::::::::: ...........•..............••••....•..•••••... . . ............. .•...•••........
..... :.::::::::::::::::S.iN···'LAk~····stCON·biRY···E .. ·~+::::::j:::j:j:j:j:j:::j:j:j:::j:j::
SWAN LAKE FIRM ENERGY
EXISTING HYDROPOWER FIRM ENERGY
1990 19911 2000 20011
YEAR8
ESTIMATED CAPACITY DEMAND
SWAN LAKE
EXISTING HYDROPOWER
YEARI
Figure 12. Comparison of power demand with existing generating facilities~
· to preserve or enhance fish and wildlife populations in the study
area, and
· to reduce, to the greatest extent possible, the study area's and
the Nation's dependence upon nonrenewable resources as a source of enerqy,
particularly for producing electricity.
Screening of Potential Measures
Identification of Potential Measures
A number of possible solutions exist that could aid in the availability of
energy in the future for the study area. Potential sources of energy
considered were:
Screening Criteria
Coal
Conservation
Geothermal
Hydropower
Natura 1 Gas
Nuclear
Oil
Regional Intertie
Solar
Solid Waste
Tida 1
Wind
Wood
The screening consisted of a preliminary evaluation of the potential energy
sources to determine which measures warranted further consideration. Each
of the measures was screened initially to determine if the technology for
its development would be available before the year 1990. If it was
determined that the technology would not be available, the measure was
dropped from further consideration. The remaining available measures were
then evaluated against the criteria established for a second, more detailed
screening. Criteria used for more detailed screening of the remaining
measures included:
• cost of the measure to assure power marketability,
· scale of the measure commensurate with need,
· environmental impact of the measure to be acceptable within
established guidelines,
· social impact of the measure to be acceptable to the community, and
· compliance with existing laws.
Alternative Energy Sources
Conservation: Conservation has been defined as a reduction in the amount of
resources consumed in serving a society's current needs in order to provide
resources for the future. Conservation efforts must not preclude advances
in social well-being, standards of living, and other amenities of life.
48
p<>'
Conservation of energy under this concept involves a reduction in energy
waste at any point in the production or distribution process, as well as in
the end use of energy.
Conservation of electricity is one means of reducing the demand for electric
power, thereby reducing the need to install new generating facilities. The
doubling and eventual quadrupling of diesel fuel prices since 1968, coupled
with concern about long range fuel availability, have resulted in the
establishment of conservation practices in the Ketchikan area. Even with
conservation measures, continued community growth will require the addition
of new generating facilities.
Coal: Southcentral Alaska has two extensive deposits of coal. The Beluga
Kiver area, northwest of Cook Inlet, is not yet in production. The Healy
coal field is the only active producer of coal in the State of Alaska.
Thus, barring development of the Beluga coal fields, coal would have to be
transported by railroad to one of the coastal port facilities from which it
would then be shipped by barge to Ketchikan. Perhaps slightly less
expensive coal could be obtained from lower 48 suppliers.
Development of Beluga coal would enhance possib"ilities for coal fired power
generation, but the major obstacle in utilizing coal for electrical energy
generation in the Ketchikan area would be the high cost of transportation
and plant construction.
Natural Gas: Natural,gas is not considered a viable alternative for the
Ketchikan load center in the absence of natural gas transportation
facilities. Furthermore, national priorities may preclude its use on a
nationwide level for all electrical generation. To assume that there will
be sUbstantial cost increases for future oil and gas supplies appears
reasonable as United States domestic reserves decline, worldwide demand
increases, and foreign oil prices remain high.
Oil: Ketchikan presently relies on diesel fuel for about 17 percent of its
electrical energy needs. Because of the long lead time required for hydro-
electric projects, oil will continue to supply an increasing share of near-
term energy requirements. Based on the existing Ketchikan power system and
relative generation costs, the use of oil is a viable alternative in the
Ketchikan area. FERC selected diesel engine driven generating plants as
the alternative for the determination of power values.
Nuclear: Nuclear energy development is not seen as a likely alternative for
the study area. The relatively large size of a nuclear power plant, the
growing national sentiment against such power plants, and the existence of
other viable alternatives have precluded this alternative from further
investigation.
Geothermal: Geothermal resources may eventually provide some power
generation in Alaska; Southeast Alaska has substantial geothermal potential.
However, this source of energy is not considered to be a reasonable short
term alternative to other more proven types of power generation because of
49
the level of present technological development and high costs of
construction in Southeast Alaska. It is anticipated that the high cost of
geothermal development could not be offset by revenue from the small
Ketchikan load center. Further, no specific sites suitable for geothermal
development have yet been found in the Ketchikan vicinity.
Solar: The radiant heat of the sun is another renewable source 6f energy
that has potential for generating power. Use of solar energy to produce
electrical power on a large scale is not currently feasible in the study
area. The most ~uccessful methods for capturing the sun's rays have been
through active and passive solar heating. However, feasibility for such
heating is limited in the Ketchikan area due to a high incidence of cloud
cover. Therefore, solar power generation is not considered a feasible
a lternat i vee
Wind: Kesearch and development proposals for wind generators should
improve future capabilities of wind powered electrical generating systems.
With increased diesel fuel costs, wind generated electrical power is a
possible alternative power source for remote areas of the State with small
loads. However, wind is not thought to be a viable alternative energy
source for the study area, as it is very difficult to adapt wind energy to
present energy demands because it is unpredictable and erratic. To
effectively utilize wind energy, winds must be of sufficient speed and long
duration. As further developments are made in wind power, it may prove
feasible to feed electricity into a grid system to displace other expensive
forms of energy; however, standby capacity would still be required for calm
periods.
Tidal: Alaska coasts experience some of the largest tidal ranges in the
world, so that certain locations have potential for the generation of
electrical energy from low head reversible hydropower plants. Tidal power,
however, in the absence of multiple storage reservoirs, is only available
during lunar-solar tide peaks, which do not coincide with the normal daily
peaking requirements. Further, due to low power heads and attendant high
flows for electrical generation. capital costs are almost always excessive
and environmental impacts are usually severe. With Ketchikan's relatively
limited 15-foot tidal range and the absence of potential reservoirs, tidal
generation is not a viable alternative for this area.
Wood: Woodwaste currently is being used to fire a steam electric generating
plant at Ketchikan as part of a manufacturing process. The Ketchikan area
does have vast forest reserves that could be used for power generation but
these resources have a much higher value as wood products. With a limited
initial supply of woodwaste and an existing generating plant using much of
that supply, future facilities dependent upon wood as a primary source of
energy do not appear viable.
Solid Waste: Adequate supplies of solid waste products in the Ketchikan
area are not available to produce enough energy to meet·anticipated load
growth. This alternative is not considered feasible to meet any
significant portion of the energy needs of the Ketchikan area.
Intertie: Instead of producing the required power in the Ketchikan area,
excess power from other generating facilities could be imported by a
transmission system interconnecting with other sources. The possible
50
benefits of interconnecting Ketchikan to other Southeast Alaska load
centers would increase as the energy demand of the areas increases.
Interconnection of existing load systems elsewhere has revealed many
advantages, including flexibility, economic gains, and higher system
reliability. Interconnection of the Southeast load centerS'could lead to
cooperative long range planning to allow efficient scheduling of additional
generating plants. This in turn could lead to revenue savings through
shared reserves and take advantage of the cost differential of producing
energy in the various load centers through interarea energy sales. Because
of these advantages, this alternative was considered further.
Hydropower: Numerous hydropower resources in Southeast Alaska could be
developed to meet the needs of the local communities. The best sites
consist of glacially carved, perched lakes that are usually quite deep and
able to provide reservoir storage. Characteristics of 12 potential sites
in the Ketchikan vicinity are listed in Table 15.
=
Table 15
Potential Hydroelectric Sites in the Ketchikan Area
Dam Height Head
( feet) ( feet)
Storage Capacity Energy Installed 1/
(acre-feet) (kWh x 1,000) Capacity (KW) Site
Lake Grace 156
Mahoney Lake 25
Manzanita & Ella Cr. 80
Orchard Lake 60
Fish Creek 60
Naha River 40
Gokachin River 31
Claude Lake 40
Lake Whitman 90
Lake Perseverance 35
Cascade Creek 10
450
1,827
140
175
395
205
330
535
350
540
190
150,600
9,000
110,000
100,000
30,000
35,000
25.000
13,000
14,000
8,000
5,000
110,200
51,400
77,000
59,000
30,000
31,000
25,000
22,000
17 ,000
12,000
1,300
20,000
15,000
12,300
9,400
4,800
5,000
4.000
3,500
2,700
1,900
200
1/ Installed capacities of Mahoney Lake and Lake Grace are from this report. All
-other installed capacities were derived by assuming that 70 percent of the
average annual energy is firm and that the plant factor is 50 percent.
51
Measures Selected for Plan Formulation Studies
Hydroelectric power, an intertie between existing load centers, and diesel
fired g~neration appear to be viable alternatives to meet demands for
future electrical energy in the study area. Of the 12 hydroelectric sites
considered during preliminary investigations, only two were investigated in
detai 1: Lake Grace and Mahoney Lakes. These two sites appeared most cost
effective be~ause of their proximity to the load center, their scale, wh1ch
is commensurate with the area's needs, and the low environmental impacts
that could be associated with these sites.
Assessment and Evaluation of Alternatives
Diesel
Description: The addition of the Swan Lake project in 1984 would replace
existing diesel use for about 2 years (Figure 12), but by 1986, diesel
facilities would again be needed, primarily for meeting peaks in power
demand. By 1990, diesel would also be needed to meet energy demand.
Projected power demand would exceed the dependable capacity of existing
generating systems, both hydroelectric and diesel by 1994. Diesel units
could be added at numberous locations within the load center, as needed, to
meet increasing demands.
Diesel fired electrical generation is also the economic standard against
which alternative plans are tested. For example, the power benefits of a
given hydropower system are compared against the cost of producing the same
amount of power by constructing and operating a conventional~
state-of-the-art, diesel generation system. FERC determined the at-market
values of dependable hydroelectric power delivered in the Ketchikan area
based on: the estimated costs of power from a 6,896-kW diesel generating
unit, with a heat rate of 9,380 Btu/kWh, operating at a 58 percent plant
factor, a capital cost of $455/kW, a 35-year service life, and fuel and
lubricating costs at $1.14 and $3.69 per gallon, respectively. With
Federal financing of 7-7/8 percent, the at-market value 6f dependable power
is $58.93/kW and 88.25 mills/kWh without fuel cost escalation (January 1982
FERC price levels adjusted to October 1982 prices by the Corps of
Engineers).
Evaluation: Power costs associated with this alternative would be directly
tied to the escalating costs of diesel fuel, as detailed in Appendix C.
Projected fuel cost escallation (above the inflation rate) varied from
-0.51 to 3.7 percent, so that an increasing cost of energy would be
expected.
Because petroleum is a nonrenewable resource, it should be utilized for
high priority uses. To continue to use diesel fuel for energy production
52
when other cost effective alternatives are available is unwise from an
economic standpoint and is also contrary to State and national policies.
Impact Assessment: The environmental impacts of continued use of diesel
for electrical generation in the Ketchikan area are primarily associated
with noise and air pollution. These impacts are viewed as acceptable for
minor increased levels, but there are growing concerns about long range
effects of major additions.
Social impacts associated with continuing energy cost escalations are
already affecting business, industry, and the average household. Continued
reliance on diesel generation would force the local economy to divert a
growing proportion of its resources to electricity generation.
Lake Grace Hydropower
Description: Lake Grace is on the east side of Revillagigedo Island,
approximately 28 miles northeast of Ketchikan. The outlet of Lake Grace is
Grace Creek, which flows east into Behm Canal.
The Lake Grace project would be a controlled reservoir water source with
major project features being a thin arch concrete dam, an intake structure
at the normal lake surface elevation, which would feed into an underground
power tunnel with an incorporated surge tank, a steel penstock, and
powerhouse.
The power plant would be located on Grace Creek approximately 1 mile
upstream from its mouth. The powerhouse would contain two 6.9-kV,
10,000-kW, three-phase synchronous generators. Each generator would be
driven by a 13,810-horsepower (hp) vertical Francis turbine, with a
rotational speed of 514 rpm at a design head of 450 feet. Remote control
of the power plant would be from Ward Cove and would be accomplished
through the use of a carrier communications system. The transmission line
would run approximately 20 miles to the Carroll Inlet intertie. A detailed
description and cost estimate of the Lake Grace project is included in
Appendix E.
Evaluation: Pertinent data for the Lake Grace project are given in
Table 16.
53
Table 16
Lake Grace Project, Pertinent Data
Installed Capacity
Dependable Capacity
Firm Annual Energy
Average Annual Energy
Plant Factor
Investment Cost (including IDC)
Average Annual Cost
Interest and Amortization
Operation, Maintenance, and Replacement
Environmental Mitigation
Total Annual Benefits
Annual Energy Benefits
Annual Capacity Benefits
Annual Employment Benefits
Annual Net Benefits
Benefit-to-Cost Ratio
20,000 kW
19,500 kW
102,500 MWh
108,600 MWh
60%
$ 94,023,600
8,160,400
7,408,100
607,000
145,300
14,352,800
13,191,000
806,000
355,800
6,192,400
1.8
The estimated first costs are based on October 1982 dollars and include a
20 percent allowance for contingencies. Cost for environmental mitigation
is assumed to be 2 percent of investment costs, based on experience from
similar projects. Average annual costs are computed by amortizing the
investment cost, including interest during construction, over the 100-year
life of the project at a 7-7/8 percent interest rate, and adding operation
maintenance and replacement costs. Interest during construction (IDC) is
computed as compound interest on a uniform expenditure over the 4-year
construction period.
Computation of energy benefits takes into account the rising cost of fuel
over the general inflation rate. Because fuel cost escalation rates are
perceived to change over time, stated energy benefits are a function of a
power-an-line date of 1989, the earliest the Lake Grace project could be
completed. Also, energy benefits were determined from firm energy only,
after deleting 2 percent for line loss.
The firm energy capabilities of all hydropower units, including Swan Lake
and Lake Grace, would meet the estimated demand of the Ketchikan load center
to the year 2004 (Figure 13). Secondary energy capabilities of existing
hydropower plants may be used to meet further demand. Because there
appears to be no identifiable demand for Lake Grace's secondary energy
within the foreseable future, no secondary energy benefits were claimed.
At the power-on-line date of 1989, hydropower capacity would replace the
use of existing diesels. In 1994, if Lake Grace was not employed, new
diesel capaCity would be required to meet demand. Therefore, capacity
benefits were claimed starting in 1994 and were considered to replace the
installation of new diesels. Existing diesel plants would be retained for
peaking and emergency uses.
54
220 . <::::
200
180
180
140
:2
~ !!120
)-
CI)
:i IOO
z
1&1
2
ESTIMATED
ENERGY
DEMAND
LAKE GRACE FIRM ENERGY
SWAN LAKE FIRM ENERGY
EXISTING HYDROPOWER FIRM ENERGY
YEARS
.",.
7~----------------------------------------------------------~
80 ESTIMATED CAPACITY DEMAND
!SO
LAKE GRACE
20
SWAN LAKE
EXISTING HYDROPOWER
IHO Ie .. 1"0 I'M 2000 YEARS
Figure 13. Comparison of power demand with addition of the Lake Grace
project to existing facilities.
Impact Assessment: There are two major environmental concerns with the Lake
Grace project. The first is an institutional concern, because the project
site is now within the new Misty Fjords National Monument. The second
concern is for the natural environment in which the project would be placed.
Alaska National Interest Lands Conservation Act (ANILCA), Public Law 96-487,
established the Misty Fjords National Monument within the Tongass National
Forest. Land status as a national monument is normally considered to
preclude structural development within a monument. However, Sections 1101
and 1102 state, in part, " ..• to minimize the adverse impacts of siting
transportation and utility systems within (national monument) units
established or expanded by this act ••. (which includes) systems for the
transmission and distribution of electric energy." This statement could
indicate a potential for some forms of development within Misty Fjords
National Monument.
Also, Section 1319 states, "Nothing in this Act shall be construed as
limiting or restricting the power and authority of the United States or--
(1) as affecting in any way any law governing appropriation or use of,
or Federal right to, water on lands within the State of Alaska;
(2) as expanding or diminishing Federal or State jurisdiction, responsi-
bility, interests, or rights in water resources development or control; or
(3) as superseding, modifying, or repealing, except as specifically set
forth in this Act, existing laws applicable to the various Federal agencies
which are authorized to develop or participate in the development of water
resources or to exercise licensing or regulatory functions in relation
thereto. "
This statement is considered to reference the Wilderness Act, Public Law
88-577, which states: "Within wilderness areas in the national forests
designated by this Act, (1) the President may, within a specific area and
in accordance with such regulations as he may deem desirable, authorize
prospecting for water resources, the establishment and maintenance of
reservoirs, water conservation works, power projects, transmission lines,
and other facilities needed in the public interest, including the road
construction and maintenance essential to development and use thereof, upon
his determination that such use or uses in the specific area will better
serve the interests of the United States and the people thereof than will
its denial."
It appears that there might be potential for development of the Lake Grace
project, but only with Presidential approval and with Congressional
concurrence. However, Section 1105.2 of ANILCA states that authorizations
with respect to a transportation or utility system may be authorized if
" •.• there is no economically feasible and prudent alternative route for the
system." Although the specific wording addresses utility systems not in
terms of the generating source (the power plant itself), it is assumed that
the same intent of the law may be applied to the generating source. That
is, if there is an economically feasible and prudent alternative to the
Lake Grace project, the alternative must be considered a priority.
56
.-
Salmon populations in Grace Creek could be adversely affected by changes in
the thermal regime below the powerhouse. Pink and chum salmon are the
primary users of this system. Terrestrial habitat losses due to filling of
the reservoir would involve about 100 acres of bottomland open meadow and
470 acres of mixed conifer old growth forest. Another 370 acres of old
growth forest would be altered by construction of the transmission line.
Lesser amounts of habitat would also be affected by construction of other
project related facilities. In general, most species of wildlife could be
adversely affected by project related habitat losses.
Mahoney Lakes Hydropower
Description: The Mahoney Lakes are located about 6 air miles northeast of
Ketchikan and about 5 miles from the Beaver Falls hydropower plant. Water
from the upper lake, at elevation 1,954 feet, flows down a cascade to the
lower lake, at elevation 80 feet, and into George Inlet from Mahoney Creek.
Upper Mahoney Lake would be tapped at a water surface depth of 225 feet
with lake entry from a tunnel excavated from a portal on the lower Mahoney
Lake side of the mountain between the two lakes. The penstock would be
5,370 feet long and 36 inches in diameter. A 25-foot binwall dam would be
built at the outlet of the upper lake to optimize water storage.
The powerhouse would be located approximately 500 feet from the edge of the
lower lake and would contain three synchronous generators with a total
installed capacity of 15,000 kW and a dependable capacity of 14,400 kW.
Each generator would be driven by a Pelton wheel turbine with a design head
of 1,820 feet. Average annual energy of the system would be 51,390 MWh.
Remote control of the power plant would be from Ketchikan by a carrier
cOlTImunication system. The Mahoney Lakes project power would be delivered
to an enlarged Beaver Falls substation by a 4.9-mile, 34.5-kV transmission
line.
Evaluation: Pertinent data for the Mahoney Lakes project are given in
Table 17.
57
Table 17
Mahoney Lakes Project, Pertinent Data
Installed Capacity
Dependable Capacity
Firm Annual Energy
Average Annual Energy
Plant Factor
Investment Cost (Including IOC)
Average Annual cost
Interest and Amortization
Operation, Maintenance, and Replacement
Environmental Mitigation
Total Annual Benefits
Annual Energy Benefits
Annual Capacity Benefits
Annual Employment Benefits
Annual Net Benefits
Senefit-to-Cost Ratio
15,000 kW
14,400 kW
38,090 MWh
51 ,390 t~Wh
30%
$50,084,300
4,341,500
3,863,800
394,900
82,800
8,263,400
7,493,200
600,400
169,800
$ 3,921,900
1.9
The estimated first costs were based on October 1982 dollars and include a
20 percent allowance for contingencies. Cost for environmental mitigation
was included. Average annual costs were computed by amoritizing the
investment cost, including interest during construction, over the 100-year
life of the project at a 7-7/8 percent interest rate. Operation,
maintenance, and replacement costs were then added. Computation of energy
benefits takes into account an escalating fuel cost and is a function of a
1989 power-on-line date.
Two years after installation of Mahoney Lakes, estimated energy demand
would exceed the firm energy capability of all combined hydropower (Figure
14). Because the demand for energy far exceeds the amount from Mahoney
Lakes, all its secondary energy could be used and was given full credit for
the fuel it would displace. ~y 1999, estimated demand would exceed all
hydropower capability.
Capacity benefits were claimed from 1994, the time at which estimated
demand would exceed all existing capacity, including diesel capacity. At
that point, if the Mahoney Lakes project was not employed, new diesel
capacity would be required. With the Mahoney Lakes project, existing
diesel plants would be retained for peaking and emergency uses.
Impact Assessment: There are two major environmental concerns with the
Mahoney Lakes project. The first is a land ownership concern, as the
project is within national forest and native corporation lands. The second
concern is for the natural environment in which the project would be placed.
The majority of project facilities, staging and camp areas, penstock, and
powerhouse, would be on patented Cape Fox Corporation land. The majority
of the transmission line would lie within lands selected by Cape Fox and
Sealaska Corporations under the Alaska Native Claims Settlement Act, but
not yet conveyed by the U.S. Forest Service.
58
An estimated 18 acres of old growth forest adjacent to the lower lake,
which is interspersed with small patches of bog, would be altered or
eliminated by the project features. Another 45 acres of forest would be
cleared for the transmission line and maintained in a sub-climax
condition. While some displacement of resident wildlife would occur during
construction, there would not be a significant loss of habitat.
Approximately 19 acres of bedrock and alpine vegetation would be inundated
at the upper lake. Because plant density and productivity are relatively
low, and the acreage to be flooded would be small, this loss would not be
significant.
Diminished flows from the upper water basin would result in the loss of the
waterfalls on Upper Mahoney Creek. The relative esthetic value of the
falls is difficult to measure, because the number of visits by people to
within viewing range is unknown, and probably incidental to other
activities. The significance of this loss is not readily apparent, but
would diminish the esthetic values for those who perceive an undisturbed
natural environment as desirable.
The altered flow characteristics of Upper Mahoney Creek could, however,
have a significant impact on sockeye salmon spawning in Mahoney Lake.
Water flowing through the highly permeable gravels of the stream bed and
entering the rim of the lake creates suitable spawning conditions. Either
insufficient underground flows or the colder water of the upper lake could
decrease spawning.
Mitigation: Under normal rainfall conditions, 20 percent of existing water
flow in Upper Mahoney Creek would remain from direct runoff into the creek
after dam installation at the upper lake. This water would supply a
portion of the interflow at favorable temperatures and help maintain the
upwelling effect for spawning at the rim of the lower lake. Tailrace water
from the powerhouse would be redirected back to the upper creek about 500
feet upstream from the lower lake to assure adequate water flows to
spawning areas. During critical spawning and incubation periods, pumped
water from the lower lake could be added to warm tailrace waters.
Implementation Kesponsibilities: The proposed project would be designed
and constructed by the Corps of Engineers. Overall project administration,
including power sales contracts, billing, accounting, and annual
inspection, would be provided by the Alaska Power Administration.
Technical services such as electronic systems maintenance and repair, and
staff for major maintenance activities, would be provided on an as-needed
basis by utility personnel supplemented by staff from Alaska Power
Administration headquarters in Juneau. Transmission line maintenance and
major power plant maintenance, sIKh as turbine overhaul, would be done by
the Alaska Power Administration. All project costs would be repaid with
interest through revenues derived from the sale of project power.
59
220
20
180
160
14 ..
~ 120
~
CII
l:i IOO
z ..,
80
40
20
ESTIMATED ENERGY DEMAND
.:-r:. .....: ....
~:".I-~,,1 •••
...,c •• :: "J~JtI;.L; .....
MAHONEY LAKES FIRM. ENERGY
SWAN LAKE FIRM ENERGY
EXISTING HYDROPOWER FIRM ENERGY
70T-----------------------------------------------------------------------,
60 ESTIMATED CAPACITY DEMAND
•••••••••••••••••••••••••• !!l •••••••••••• •••••••••••••••••••••••••• r:; •••••••••••••
::::::: e:XISTING·::::··· :.::::::::::::::: •.•••.............. . .•................ ..............•.. . .................... . •.......•...... . ..........•............
MAHONEY LAKES
SWAN LAKE
EXISTING HYDROPOWER
YEARS
Figure 14. Comparison of power demand with addition of the Mahoney Lakes
project to existing facilities.
Intertie
Description: The Alaska Power Administration has undertaken a study of the
feasibility of interconnecting a number of communities in Southeast Alaska
to make it possible to utilize the hydroelectric power that is available in
some areas, to minimize fossil fuel generation in other areas, and to
supply hydroelectric power to the U.S. Borax Quartz Hill Mine. The Alaska
Power Administration study is an extension of previous Alaska Power
Administration studies and other studies and provides designs and cost
estimates for a number of transmission schemes. Fourteen transmission
system configurations are being considered which involve the Ketchikan
area. Figure 15 shows the location of the main communities and hydropower
plants in Southeast Alaska, as well as the main transmiSsion routes that
are being considered in the Alaska Power Administration study.
The cost of the various transmission interconnection plans developed by this
study will be utilized by the Alaska Power Administration in an overall
system expansion cost study that will consider the cost of generation,
transmission, operation, and maintenance, including fuel costs for the
interconnected system. Only a draft reconnaissance report of designs and
costs was available at the time of publication of this report. The Alaska
Power Administration draft report concluded that the intertie
configurations appeared engineeringly feasible. No conclusions were drawn
on economic feasibility, although many of the plans would be dependent on
development of several new large hydropower projects, including the Thomas
Bay project at Petersburg and the Mahoney Lakes project at Ketchikan. The
interconnection configurations under consideration, which intertie
Ketchikan and Petersburg/Wrangell, would require that at least the Thomas
Bay project be constructed to meet the combined demand of three communities
through the year 2000. The Alaska Power Administration's overall system
expansion cost study, due to be completed in mid-1983, will determine the
economic feasibility of the proposed intertie configurations.
Interties to other existing nearby power systems were considered by the
Corps of Engineers. An intertie between the Tyee Lake project at Wrangell
and the Swan Lake project at Ketchikan warranted immediate evaluation.
These investigations did not include transmission systems that had as their
primary function the delivery of power to Quartz Hill. In the early years
of the Tyee Lake project, the Petersburg/Wrangell area would have excess
energy that could be transferred to the Ketchikan area (Figure 16). In
1989, at completion of the line, approximately 24,000 kWh/year could be
transferred. Peak energy transfer would be about 50,000 kWh in 1994 when
the increasing Ketchikan demand would equal the decreasing
Petersburg/Wrangell reserves. By the year 2009, all of Tyee's capacity
would be needed to meet the demand of the Petersburg/Wrangell load center.
Power would be delivered to the Ketchikan load center through approximately
52 miles of overhead transmission line and 2.1 miles of submarine cable.
The overhead transmission line would be a combination of steel towers and
wood poles. Only small portions of the transmission route would be
accessible by road.
61
"
...... ........
.-' \~H I-FEHORSE
I .
20f11W
SOUTHEAST ALASKA
MAIN TRANSMISSION ROUTE r'-'
i
.I
./
i I
SKAGWAY
<~
'\.._.\
Rift .. A.., ........ ALAMA ':l:;'ow:" aouT"UST tfYDIIOeLICTMC ~. linn.
_DIIIIIIoI
"-', "
o 10 20 30 40 50mil,s~~:;:;~~§g~i:~~~
scale .. ~~
DC LINE
------AC LINE (odditions)
-•• _ •• -•• -AC LINE
(existing or \6Ider construction)
~~~~
.~~~~~--
............... -..... ~ ................
"-~-"'~""~~~~~~ .~~.-''' .. ~~~~
. ~-:::-::::::::::::::-'::~:::::-;:::.::::::::;::-~~,':::..":::...~ ~~ -~~,-
~"""""""'-'-'~~~~-"'-"'-"
'-~~~""~""--~~~'-~~~
.-"-"-" .... ~~ •.• ~~ ...... ~'--"'-• .A •
..... -"-""-................... A.-. • ...",~_~ ..... '
,-"-,-~~"-",-"",-",,,-.. ,,-... -...... ,, .. ,
AA~ PRINCE RUPERT 2011W
Flgur ••
15
'-. \
'-'-'\
BORAX
Evaluation: Pertinent data for the Tyee/Swan Lake transmission intertie
are given in Table 18.
Table 18
Tyee Lake/Swan Lake Transmission Intertie, Pertinent Data
Transmission Line
Capacity
Uverhead Length
Submarine Cable Length
Project Life
Investment Cost (Including IDC)
Average Annual Cost
Interest and Amortization
Operation, Maintenance, and Replacement
Total Annual ~enefits
Annual Energy Benefits
Annual Employment Benefits
Annual Net Benefits
Benefit-to-Cost Ratio
138 kV
52 mil es
2.1 miles
20 years
$44,032,700
4,672,600
4,443,300
229,300
4,560,900
4-,373,300
187,600
-111,700
0.98
The economic analysis was conditioned by several parameters. (1) The cost
of the Tyee Lake project was considered a sunk cost with no part of its
costs paid by Ketchikan. In practice, there may be cost sharing, but
reassignment of costs would not change the net economic benefit to the
region. (2) Simply as an alternative source of power, the transmission
line was considered to be justifiable only by the energy it would
transfer. (3) The Tyee Swan Lake intertie would be an alternative source
of energy for Ketchikan for 20 years. Therefore, the service life and the
economic analysis period were considered as 20 years. Under these
parameters, the intertie is not a true alternative to hydropower or
diesel.
Energy transferred from Tyee Lake was considered for priority use as firm
energy when energy benefits were counted (Figure 16, top). Counting
benefits in this manner would show the maximum benefit that could ever be
reasonably obtained. In practice, existing secondary energy from local
hydropower plants could be used, when available, before energy from Tyee
Lake was used (Figure 16, bottom). Also much of the energy available from
Tyee is itself secondary energy and may not be available at all times
during the transfer period.
Transmission line cost estimates were determined from May 1982 Tyee Lake
project bids, with a 20 percent allowance for contingencies. Average
annual costs were computed by amoritizing the investment cost, including
interest during a 4-year construction period, over the 20-year life of the
project, at a 7-7/8 percent interest rate. Operation, maintenance, and
replacement costs were then added. Computation of energy benefits takes
into account an escalating fuel cost and is a function of a 1989 completion
date.
63
220 PETERSBURG/WRANGELL AREA
ESTIMATED ENERGY RESERVES
200
~ •
180
140
!!. 120 ,.
! 100 z
III
80
60
40
KET.CI1IKAN AREA ESTIMATED
ENERGY DEMAND
ENERGY TRANSFER"E;D·.
SWAN LAKE FIRM ENERGY
20 EXISTING HYDROPOWER FIRM ENERGY
140
60
40
20
1985 IUO
PETERSBURG/WRANGELL AREA
ESTIMATED ENERGY RESERVES
1ge1l
YEARS
2000
KETCHIKAN AREA ESTIMATEg,
ENERGY DEMAND "
"
SWAN LAKE FIRM ENERGY
EXISTING HYDROPOWER F1RM ENERGY
le81 1990 1995
YEARS
2000
20011
2006
Figure 16. Comparison of power demand with addition of the Tyee Lake/
Swan Lake intertie.
--
2010
2010
An intertie between the Petersburg/Wrangell and the Ketchikan areas is not
in itself a long term alternative for meeting the Ketchikan demand. It
appears that additional development of hydropower would be needed, both to
make a transmission line more economical and to meet the power demand.
Power demands of Ketchikan could be met by development of local hydropower
potential, thus eliminating the need for an intertie.
Potential for an economical intertie may exist, but it would appear to be
primarily a function of Quartz Hill energy demand. Projects such as Thomas
Bay would require an intertie and could help meet the demand of the
municipalities and the Quartz Hill project. However, development of such
an intertie is not within the purview of the Corps of Engineers.
Impact Assessment: An intertie to the Tyee Lake project would alter
approximately 400 acres of terrestial habitat within the Tongass National
Forest. Some displacement of resident wildlife would occur but, because
there would not be a significant loss of habitat, the impacts may not be
major when viewed regionally.
Avian mortality resulting from collisions with overhead wires and
disruption of nesting and feeding areas are a concern. These impacts
should be minimized by design and placement of the transmission line.
Submarine portions of the line could produce electric or magnetic fields
that could affect fish migrations or other marine ecosystem disturbances.
These.effects would need to be identified.
65
CUMPA~SION OF DETAILED PLANS
Diesel generation has the lowest installation costs for new capacity of any
alternative considered, and also has the advantage of being sequentially
installed as needed with costs incurred only after the need has been
clearly identified. However, the cost of diesel generated energy would be
largely dependent upon high fuel costs and the relative higher maintenance
costs of diesel. The 35-year life expectancy of the diesel units would
also necessitate several replacements during the life of an alternative
hydropower project. The increasing burden of energy costs would have a
negative impact on the economy and on the social well-being of the
community. Environmentally, diesel generation would adversely effect the
ai r quality of the Ketchi kan community area by combust i on by-products and
heat emissions. The esthetic quality of Ketchikan would be minimally
effected since new units would most likely be added to existing
facilities. However, diesel generation would also preclude the degradation
of pristine areas that would accompany development of hydropower.
The Lake Grace project is the larger of the two hydropower alternatives
considered. Figure 13 shows how Lake Grace capabilities would fit into the
existing KPU system. The firm energy of Lake Grace, when added to the firm
energy of existing hydropower, would meet the expected demand to the year
2003. When all hydropower secondary energy is included, energy demand
would be met to the year 2011, assuming demand would continue to grow at
current rates. The added capacity of Lake Grace would satisfy increasing
demand until 1996, 7 years after the power-on-line date. At that time,
existing diesel units could be employed to meet demand peaks. No new
diesel capacity would be needed until 2005.
When compared to diesel installations, initial investment cost of the Lake
Grace project would be greater; but once installed, operation and
maintenance costs of hydropower would be lower. Over the life span of the
Lake Grace project, the cost of electricity produced by Lake Grace would be
55 percent as costly as power produced by diesel.
Power generation by Lake Grace hydropower rather than by additional diesel
installations would reduce Ketchikan1s future dependance on non-renewable
resources. This would be in line with Federal policies of resource
Inanagement. Use of hydropower would also eliminate the expected emission
problem within Ketchikan that would be associated with additional diesel
generation.
Hydropower development would have other impacts that the diesel alternative
would not have. The Lake Grace project would have an impact on the
pristine character of the Misty Fjords National Monument. Generally,
hydropower development is not allowed in national monuments, unless
specifically approved by the President and the Congress. The law that
created Misty Fjords National Monument did not address hydropower
development, although it did allow for development of transmission lines on
monument lands.
66
Figure 14 shows how Mahoney Lakes capabilities would fit into the existing
KPU system. The firm energy of Mahoney Lakes, when added to the firm
energy of existing hydropower, would meet expected demand to mid-1992,
which is about 3 years after the power-on-line date. When all hydro-
power secondary energy is included, energy demands would be met until the
year 2000, if secondary energy would be available when needed. The added
capacity of Mahoney Lakes would satisfy increasing demand until mid-1992,
about 4 years after the power-on-line date. At that time, existing diesel
capacity could be employed to meet demand.
The Mahoney Lakes project would have greater initial costs than the diesel
alternative but would have lower operating and maintenance costs. Over the
life span of the Mahoney Lakes project, the cost of electricity produced by
hydropower would be 52 percent as costly as power produced by diesel.
Environmentally, Mahoney Lakes hydropower would eliminate the emission
problems of expanded diesel generation and reduce Ketchikan's dependance on
non-renewable resources. However, in doing so, the hydropower project
would have impacts elsewhere. The esthetic quality of the Mahoney Lakes
region would be affected, as would a sockeye salmon resource. Recommended
mitigation measures would reduce the impact to salmon.
A comparison of pertinent data of the Lake Grace and Mahoney Lakes projects
is given in Table 19. Because the Lake Grace project is the larger project
in terms of energy output, it would satsify the growing electrical demands
of Ketchikan for a longer time. The Lake Grace project also has the larger
net benefit. However, the cost of the project is greater than the Mahoney
Lakes project and is more sensitive to fuel cost escalation.
Environmentally, the Mahoney Lakes project has less total impact. Lands
taken for the smaller reservoir and shorter transmission of the Mahoney
Lakes project are less than the lands needed for the Lake Grace project.
The Mahoney Lakes project would also affect fewer numbers of spawning
salmon.
The major concern with the Lake Grace project is that the project site is
now within the Misty Fjords National Monument. Mahoney Lakes project lands
are in national forest lands, which could be obtained by long term permit,
and native corporation lands. These lands appear to be more accessible
than national monument lands.
Because an economically feasible and implementable alternative exists at
I~ahoney Lakes, the Lake Grace project is not selected for development at
this time. The Mahoney Lakes project is selected because it would meet
most of the needs of Ketchikan through the year 2000 and would provide
power at a reasonable cost.
67
Table 19
Mahoney Lakes versus Lake Grace, Comparison of Pertinent Data
Item
Dependable Capacity (kW)
Firm Energy (MWh)
Average Annual Energy (MWh)
Investment Cost
Average Annual Cost
Average Annual Benefit 1/
Annual Net Benefit -
Benefit-to-Cost Ratio
Lake Grace
19,500
102,500
108,600
$ 94,023,600
8,160,400
14,352,800
$ 6,192,400
1.8
Mahoney Lakes
14,500
38,090
51,390
$50,084,300
4,341,500
8,263,400
$ 3,921,900
1.9
1/ Based on the cost of producing the same amount of power by diesel
driven generators.
Potential intertie systems that were considered as alternative sources of
power for Ketchikan were of moderate transmission length, where reserve
capacities from adjacent load centers could be used. An intertie
constructed solely to transfer declining reserves elsewhere to Ketchikan
does not appear economically feasible, nor would it, in itself, supply the
energy needs of Ketchikan for the foreseeable future.
A regional intertie system of the scope being studied by the Alaska Power
Administration could provide an alternative. However, it is not yet known
if a large intertie system is viable. It is doubtful that power could be
supplied for a lesser cost than development of hydropower in the Ketchikan
area.
Rationale for Designation of the NED Plan
The National Economic Development (NED) objectives are achieved by
increasing the value of the Nation's output of goods and services and
improving national economic efficiency. Based on this criteria, the NED
plan is the Lake Grace hydropower project. This plan would provide net
annual benefits exceeding any other alternative plan. The average net
annual NED benefit over the life of the proposed project is estimated at
$6,315,800.
Rationale for the Tentatively Selected Plan
The r'lahoney Lakes project is the most reasonable plan to develop at this
time. Although the Lake Grace hydropower project would provide greater net
benefits, the project lies in a national monument where hydropower
development is not practical as long as economically feasible alternatives
exist. Because there are other viable alternatives available, the Lake
Grace project is not selected.
68
A transmission intertie alternative based on transfer of reserve hydropower
capacity from outside the Ketchikan area would satisfy the growing power
demand only temporarily. Also, the amount of energy that could be
transferred from existing sources would not economically justify the
intertie. One or more of the regional intertie systems under study by the
Alaska Power Administration may be viable. This, however, does not
preclude the continuing development of hydropower. Sufficient information
was not available at the time of publication of this report to select this
alternative or dismiss it completely. When on-going studies are completed,
the findings of those studies will be included in this report.
Of the remaining alternatives, Mahoney Lakes hydropower and diesel, the
IVlahoney Lakes hydropower proj ect is the superi or a lternat i ve. The cost of
energy from Mahoney Lakes would be only 52 percent of diesel energy.
Environmentally, the impacts of the two alternatives are not readily
comparable. However, hydropower development would lessen the dependence on
non-renewable fossil fuels and environmental impacts of the project would
be mitigated. The Mahoney Lakes project, with the retention of existing
diesel units, could meet the power demands of the Ketchikan area for the
foreseeable future. Therefore, the Mahoney Lakes hydropower project is the
tentatively selected plan.
The Tentatjyely Selected Plan
This section includes a brief overview of the tentatively selected plan,
its major components, mitigation measures, constuction considerations,
operating characteristics, and economic summary. A detailed description of
the selected plan and alternatives considered in the optimization of the
selected plan are described in Appendix D.
Plan Overview
The Mahoney Lakes are located about 6 air miles northeast of Ketchikan and
about 5 miles from the Beaver Falls hydropower plant. Water from the upper
lake, at elevation 1,954 feet, flows down a cascade to the lower lake, at
elevation 80 feet, and into George Inlet from Mahoney Creek.
Upper Mahoney Lake would be tapped at a water surface depth of 225 feet with
a multipipe intake system. Lake entry would be accomplished from a 10-foot
horseshoe shaped tunnel excavated between the two lakes from a portal on
the lower Mahoney Lake side of the mountain. The multipipe system would
be manifolded into a 36-inch remote controlled spherical valve at the head
of a 36-inch penstock. A 25-foot binwall dam would be built at the outlet
of the upper lake, raising the maximum water surface elevation of the
reservoir to 1,979 feet. The binwall cells would be keyed into the rock
sidewalls of the channel and be filled with rock. The upstream face of the
dam would have a welded steel membrane. A 40-foot-wide section would be
set 1 foot lower than adjacent sections to confine normal streamflow to the
center of the dam. Uuring high runoff periods, flow would be over the
dam's entire length.
The penstock would be a 5,370-foot-long, all welded steel structure
supported on concrete piers 40 feet on centers. The penstock would extend
69
through the tunnel from the valve control chamber 4,000 feet to the portal
and continue above ground along the natural land contour for the remaining
1,370 feet.
The powerhouse would be located approximately 500 feet from the edge of the
lower lake at elevation 90 feet and would discharge tailrace waters via the
upper creek into the lake. The powerhouse would contain three synchronous
generators with an installed capacity of 5,000 kW each (15,000 kW total)
with a dependable capacity of 14,400 kW. Each generator would be driven by
a Pelton wheel turbine with a design head of 1,820 feet. Average annual
energy of the system would be 51,390 MWh. Remote control of the power
plant would be from Ketchikan by use of a carrier communication system.
The Mahoney Lakes project power would be delivered to an enlarged Beaver
Falls substation by a 4.9-mile, 34.5-KV transmission line.
Access to the project site would be by water from George Inlet or by
helicopter. Access to the portal and the damsite, as well as construction
of the transmission line, would be by helicopter.
Fish and Wildlife Mitigation
Sockeye salmon, both anadromous and resident forms, are present in Mahoney
Lake. Because of limited sockeye runs in the Southeast Alaska, the
estimated 300 to 500sockeyes observed (1982) within the Mahoney Lakes
system are considered to be a significant resource. Also, historical
records indicate larger runs in the Mahoney Lakes system and, therefore,
the goal of the recommended mitigation is to protect both existing and
potential sockeye resources. Because of the unpredictable and turbulent
flows of the tributaries flowing into the lower lake, spawning occurs in
the lake itself rather than in the streams. Within the lake, sockeyes have
been observed spawning only near the western shore along the delta formed
by Upper Mahoney Creek.
The creek bed of the last 1,500 feet of Upper Mahoney Creek is composed of
highly permeable gravels. There is considerable interflow through these
gravels into the lake. The spawning impulse in sockeyes found in the lake
is apparently triggered by the temperature of water upwelling from these
gravels. Most of this flow, which comes from the upper lake, would be
diverted through the power plant and returned into the upper creek, about
500 feet upstream of the lake. Returning the flow to the stream is
expected to maintain the upwelling effect. However, water drawn from the
upper lake would be colder than the normal surface flows and could affect
spawning and proper egg development.
To nlaintain tolerable water temperatures at points of upwelling during the
critical spawning and incubation periods, warmer water would be pumped from
the lower lake and mixed with tailrace waters. An 18,000-gallon-per-minute
(40-cfs) pump would be placed at the lower lake approximately 1,500 feet
from the powerhouse, with the intake being sufficiently distant from the
spawning areas. A 24-inch steel pipeline would discharge the warmer water
at the tailrace stilling basin where it would mix with the 4°C water from
the upper lake. Instrumentation would be installed to record temperatures
in the spawning area and a monitoring program would be established for
qual ity control.
70
-
Lands
Project lands are held by the U.S. Forest Service or native corporations.
Lands held by the U.S. Forest Servie could be obtained by a long term
permit or by transfer, since the majority of project facilities on U.S.
Forest Service land are underground. Surface use would be unaffected by
the project and the U.S. Forest Service could continue its traditional
resource management.
The majority of project facilities, docks, roads, staging and camp areas,
penstocks and powerhouse, are on patented Cape Fox Corporation land.
Sealaska, also a native corporation, owns the subsurface estate on these
lands. An interest in the subsurface estate would also be required for the
majority of these facilities.
Most of the transmission lines would be within lands selected by Cape Fox
and Sealaska Corporations, but these lands have not yet been conveyed by
the U.S. Forest Service. Permanent rights-of-way over these lands would be
difficult to acquire prior to title conveyance to the native corporations.
Operation and Maintenance
The Mahoney Lakes project would be owned and managed by the Alaska Power
Administration, but would be operated by KPU with supervisory control from
a centralized operations control center in Ketchikan. Project maintenance
would be performed by Federal maintenance operators assigned to the project
and supplemented by KPU maintenance personnel. These individuals would
operate the project under emergency situations. Technical services such as
electronics systems, maintenance and repair, meter relay mechanics, and
staff for major maintenance activities would be provided on an as-needed
basis by KPU personnel and be supplemented by the Alaska Power
Administration headquarters and other hydroelectric projects.
Transmission line maintenance and major power plant maintenance such as
turbine overhaul would require additional manpower that could be provided
either by the KPU staff or personnel from other Alaska Power Administration
projects. The Federal maintenance operators would do routine transmission
line inspections and assist in repairs. Overall project administration,
including power sales contracts, billing, accounting, and annual
inspections, would be provided by the Alaska Power Administration
headquarters office in Juneau, Alaska.
Cultural Resources
The project will have little impact on cultural resources. There are no
known historical or archaelogical sites within the project area. Those
impacts that have been identified, such as the slight social and economic
growth of Ketchikan, are considered positive.
Economic Summary
All costs and benefits are given in October 1982 dollars for a project life
of 100 years. The period of economic analysis was from a power-on-line date
71
of 1989, extending the 100-year project life to 2089. Average annual costs
and benefits were determined from project totals by applying the appropriate
capital recovery factor associated with a Federal interest rate of 7-7/8
percent.
Project Costs
Summary cost estimates are given in Table 20 and detailed estimates are in
Appendix D. Estimated investment costs, including interest during
construction and environmental mitigation are $50,084,300. Interest during
the 4-year construction period was determined as a uniform expenditure
throughout construction. Project costs include a 20 percent contingency
and 16 percent for engineering, design, supervision, and administration.
Operation, maintenance, and replacement costs were estimated at $394,400
annually. Detailed operation and maintenance estimates are given in
Appendix G. The total annual cost of the Mahoney Lakes project is
$4,341,500.
72
Table 20
Summary Cost Estimates, Mahoney Lakes Hydropower Project
Item and Description
Mobilization and Demobilization
Lands and Damages
Reservoir Clearing
Dam, 25-foot binwall
Intake Chamber, multipipe lake entry
Penstock, 36-inch-diameter steel
Powerhouse
Turbines and Generators, 3 units, 15 MW total
Accessory Electrical Equipment
Auxiliary Systems and Equipment
Switchyard
Transmission Line, 34.5 kV
Beaver Falls SUbstation Modifications
Roads and Bridges, beach to powerhouse
Buildings, Grounds, and Utilities
Heliport, Portal, and Dam Access
Mitigation
Subtota 1
Contingencies (20%)
Engineering and Design (8%)
Supervision and Administration (8%)
Total First Cost
Interest During Construction
Total Investment Cost
Average Annual Cost of Construction
Operation, Maintenance, and Replacement
Average Annual Project Cost
. Benefits
Total Cost
$ 2,200,000
66,000
85,000
1,513,000
1,079,000
11,437,000
1,862,000
4,608,000
1,267,000
761,000
712,000
1, 132,000
113,000
786,000
1,139,000
2,026,000
597,000
31,383,000
6,277,000
3,013,000
3,254,000
43,927,000
6,157,000
50,084,000
3,946,600
394,900
$4,341,500
Energy, capacity, and employment benefits were claimed for the project.
The benefit value of hydroelectric power is measured by the cost of
providing the equivalent power from the most likely alternative source, in
this case, diesel.
FERC determined the at market values of dependable power based on the cost
of a 6,896-kW diesel unit, with a heat rate of 9,380 Btu/kWh, a 58 percent
plant factor, a capital cost of $455/kW, and a service life of 35 years.
Power values were $58.93/kW and 88.25 mills/kWh without fuel cost
escalation. (Figures were updated to October 1982 price levels by the
Corps of Engineers.)
73
Fuel cost escalation above the inflation rate was used in the energy benefit
analysis. Costs were escalated for 30 years beyond the power-on-line date
and then held constant to the end of the project life. Real fuel cost
escalation rates were based on the 1982 Data Resources Incorporated Energy
Review Report. Escalation rates and the resulting value of energy are
given in Table 21.
Table 21
Real Fuel Escalation Rate and Value of Energy
Period Escalation Rate {%~
1982-1985 -0.53
1986-1990 4.23
1991-1995 3.71
1996-1999 2.65
2000-2019 3.53
2019-2089 0
Year Energy Cost (mills/kWh~
T982 88.25
1985 86.94
1989 (power on 1 i ne) 103.24
1995 125.63
2000 142.44
2019 (end of applied 270.32
escalation)
2089 (end of project) 270.32
Both firm and secondary energy were claimed as benefits, deducting 2
percent of plant output for transmission losses. Secondary energy was
considered at the same value as firm energy since there is an identified
need for this energy and, on an average annual basis, it would be available
to displace diesel energy. Average annual energy of the Mahoney Lakes
project would be 51,390 MWh with an annual benefit of $7,493,200.
A capacity benefit of 14,400 kW, minus 5 percent for transmission losses,
was claimed starting in 1994. During 1994, estimated demand would exceed
all capacity, including the Swan Lake addition and existing diesel, which
would require either additional new diesel installation or Mahoney Lakes
hydropower. The Mahoney Lakes project was considered to replace the use of
eXisting diesel units, and the existing diesel units were considered to
replace the need for new diesel installations. The average annual capacity
benefit was $600,400.
Project benefits for employment are claimed to show the impact of project
construction in the Ketchikan area. NEU employment benefits were based on
the construction cost of the project and the unemployment characteristics
of the Ketchikan area. Amounts earned by otherwise unemployed local
workers were amoritized over the project life. Annual NED employment
benefits claimed are $169,800.
74
Total annual benefits of the Mahoney Lakes hydropower project are
$8,259,100. Total annual estimated costs, including operation and
maintenance, are $4,341,500. Annual net benefits are $3,921,900, with a
benefit-to-cost ratio of 1.9.
75
PUBLIC INVOLVEMENT AND COORDINATION
A public meeting was held in Ketchikan on 15 March 1975. The purpose of
this meeting was to obtain input from the puhlic to help direct the study.
A related public meeting on the Rivers and Harbors of Alaska study held on
15 March 1982 revealed local support for the Lake Grace project, as it
would meet the energy needs of Ketchikan beyond 2000. The Mahoney Lakes
project would be supported if the electricity cost would be competitive
with other sources of power.
Input from Federal, State, and local officials was obtained by direct
contact and correspondence. The recommendations of the U.S. Fish and
Wildlife Service have been considered and the selected plan includes
measures to mitigate environmental effects of the project~
During the public review of this draft report, a public meeting will be
held in Ketchikan to obtain input prior to finalizing the report
recommendations.
76
CONCLUSIONS
The Alaska Power Administration has undertaken a study of the feasibility
and economics of interconnecting a number of communities in Southeast
Alaska, including Ketchikan. Reconnaissance level design and cost
estimates for a number of transmission schemes have been completed and it
has been concluded that a transmission intertie is technically feasible.
Studies on economic feasibility and identification of the most cost
effective interconnection plan are expected to be completed by mid-1983.
Findings of the Alaska Power Administration study will be incorporated
into this report prinr to finalizing a recommendation.
Surplus power from Tyee Lake would be available in the early years of
that project. Preliminary cost estimates of an intertie to transfer Tyee
energy to Ketchikan indicate it would be more cost effective to construct
a new hydropower project near Ketchikan. The Lake Grace and Mahoney
Lakes hydropower projects appear to be the two most favorable
alternatives. The Lake Grace project, the larger of the two projects,
would meet the increasing power demands of the Ketchikan load center for
a longer period, but, because of its size, is also more sensitive to fuel
cost escalation assumptions.
The Mahoney Lakes project with three smaller generating units could be
operated with a mix of base load and peaking characteristics. The Lake
Grace project would function primarily as a base load plant.
The major concern with the Lake Grace project is that the project is
within Misty Fjords National Monument. Establishment of a national
monument is an implicit intent to preserve an area in its natural state.
However, the law establishing the Misty Fjords National Monument
explicitly allows the construction of transmission facilities, under
certain conditions t which may imply an allowance of power generating
facilities also. But, a condition of allowance for a transmission
facility based on there being "no economically feasible and prudent
alternative route for the system" could implicitly be applied also to
generating facilities, which would disallow the Lake Grace project at
this time since an economical alternative exists.
Mahoney Lakes project components that are on U.S. Forest Service lands
are compatible with existing land uses, thus these lands can be obtained
by long term permit. Other project lands are patented lands or Forest
Service lands selected by native corporations but not yet conveyed.
These lands would require negotiation for the purchase of easements.
The Mahoney Lakes project would meet most of the Ketchikan electrical
needs through year 2000 at a lower cost than diesel electric generation,
even if fuel costs do not increase. Selection of this scale project
would minimize capital investment and allow opportunity to monitor actual
increases in electrical demand before decisions on long range electrical
development are made.
77
TENTATIVE RECOMMENDATIONS
I recommend that the Mahoney Lakes hydroelectric project be authorized
for Federal construction, generally in accordance with the plan described
herein, with such modifications that the Chief of Engineers may find
advisable, and in accordance with cost recovery, cost sharing, and
financing arrangments satisfactory to the President and the Congress.
Authorization of this project for Federal construction should not
preclude the development of hydroelectric facilities at this site by a
qualified nonfedera1 interest. Based on October 1982 price levels, the
total first cost of the project, including necessary transmission
facilities, is estimated at $43,927,000 for construction and $394,900
annua lly for operation, ma; ntenance, and replacements.
78
-.
DRAFT
ENVIRONMENTAL IMPACT STATEMENT
Df<AFT
ENVIRONMENTAL IMPACT STATEMENT
Proposed Hydroelectric Development on the
Mahoney Lakes System near Ketchikan, Southeast Alaska
The responsible lead agency is the U.S. Army Engineer District, Alaska.
The responsible cooperating agency is the U.S. Forest Service.
Abstract: Ketchikan is a small community -located on Revillagigedo Island
1n Southeast Alaska. Diesel generators currently supply much of the
electrical power used by area residents. High fuel costs and projected
energy demands led to an investigation of hydropower potential near
Ketchikan by the J\laska District. A hydropower development on the Mahoney
Lakes system has been proposed. The tentatively recommended l5.0-MW
project would include a multiple lake entry and dam at the upper lake,
underground and surface penstock leading to a powerhouse near the lower
lake, a 4.9-mile transmission line, dock, camp, and service road. Access
to the site would be accomplished by boat, barge, or aircraft. Alternative
designs and placement of project features were evaluated. Impacts to old
growth forest, wetlands, and water quality would not be significant. An
estimated 63 acres of wildlife habitat would be destroyed or significantly
altered by the project. About 75 additional acres of habitat may be
influenced. Anticipated negative project impacts to sockeye salmon
(Oncorhynchus nerka) in the lower lake could be mitigated by controlling
the direction and temperature of tailrace waters. Coordination with the
U.S. Fish and Wildlife Service has helped to identify environmental
concerns and minimize adverse project impacts.
SEND YOUK COMMENTS
TO THE DISTRICT ENGINEER
BY: September 19, 1983
If you would like further information
regarding this statement, please
contact:
Mr. William D. Lloyd
U.S. Army Engineer District, Alaska
Pouch 898
Anchorage, Alaska 99506
Telephone: (907) 552-2572
NOTE: Information contained in the main report is incorporated by
ref erence in the Envi ronmenta 1 Impact Statement.
SUMMARY
The Ketchikan Borough, which includes the City of Ketchikan, is located on
Revillagigedo Island in Southeast Alaska (Figure EIS-l). An estimated
population of between 11,000 and 12,000 people is reported for the
Ketchikan Borough. Commercial fishing and the wood products industry are
important to local residents. Marine or air transportation are the only
. forms of access to Ketchikan.
The City of Ketchikan currently depends on a mix of hydropower and diesel
generators to meet its electrical energy needs. Projected energy demands
and the high cost of diesel fuel prompted the city council to pass a
resolution asking the Corps of Engineers to focus attention on the study of
.potential hydropower development in the Ketchikan area. This was
consistent with a Congressional resolution that urged the Corps to
investigate hydropower feasibility throughout Alaska.
Various energy alternatives designed to meet the needs of Ketchikan were
explored; most were rejected bec~use of low feasibility. A hydroelectric
project on the Mahoney Lakes system about 6 miles from Ketchikan appeared
viable (Figure E1S-2). The tentatively recommended 15.0-MW hydroelectric
project would involve tapping into Upper Mahoney Lake to supply water, via
a 5,370-foot penstock, to a powerhouse near Mahoney Lake (also referred to
as the lower lake). A 25-foot dam at the outlet of Upper Mahoney Lake
would provide greater storage capabilities. Electricity would be conveyed
to an existing substation at Beaver Falls via a 4.9-mile transmission
line. Docking and seaplane facilities associated with site access would be
located in George Inlet and a construction camp would be located between
George Inlet and Mahoney Lake. A 1.4-mile service road would connect the
dock, camp area, and powerhouse. Additional roads were considered as
alternative forms of access to the general project site and to the penstock
tunnel portal. Various alternatives to the design or location of specific
project features were also examined.
The Mahoney Lakes system is located in a region of rugged, mountainous
topography. Cool summers, mild winters, and high precipitation are
typical. The maritime climate gives a rain forest character to the old
growth coniferous stands in the area. Muskegs occur sporadically where
conditions for their development are favorable. Between 2,000 and 3,000
feet above mean sea level, a transition from forest to alpine and
sub-alpine plant communities is encountered.
Terrestrial ecosystems adjacent to the Mahoney Lakes provide habitat for
black-tailed deer (Odocoileus hemionus), black bears (Ursus americanus),
wolves (Canis lupus), and a number of smaller mammals. Important
black-tailed deer winter habitat has been identified along George Inlet.
Bald eagles (Haliaeetus leucocephalus) are common to the area and several
nests have been found north of the project site. Grouse, ptarmigan, and
various species of songbirds are present near the Mahoney Lakes. Pink
salmon (~gorbuscha) and chum salmon (Q. ketal spawn in Mahoney Creek near
George Inlet. Mahoney Lake is used by adult anadromous sockeye salmon for
EIS-ii
.. . -, ..
. ., ~ ,.~
ALASKA
LOCATION OF
STUDY
't------r
STUDY AREA
KETCHIKAN
AREA
ftIP.II
IiiIiiI IUYEIIS AND HAR_S 1111 ALASKA
USAnllr~ SOUTHEAST HYDROELECTRIC POWER INTEA!M d~
~DiIIIncI
Figure:
EIS-1
5 o 2 10
I
SCALE IN MILES
LOCATION OF
MAHONEY LAKES
~ IiiIiII RI.YERS AND HAR_I ... ALAIKA
WAnIIrc:.,. SOUTHEAST HYDROI!lECTItfC POWER INTERI. GlInII!IMn
_DIIII'd
Figure:
EIS-2
spawning and by sockeye fry for rearing. Sockeye spawning occurs only
along the west shore of the lake and is linked to intragravel flows from
Upper Mahoney Creek. Resident fish, such as kokanee (land locked sockeye
salmon) and Dolly Varden (Salvelinus malma), are also present in the lower
lake. Upper Mahoney Lake does not contain fish.
Measurempnts of pH, alkalinity, dissolved oxygen, temperature, and
turbidit:1 did not reveal any water quality pr'oblerns in the Mahoney Lakes
system. A spectacular laO-foot waterf a 110n Upper Mahoney Creek is
perceived by many as an ~sthetically important natural feature of the
area. No significant historic or archaeological sites have been identified
within the influence of the proposed project.
An estimated 18 acres of old growth forest, interspersed with small patches
of bog, would be altered or destroyed by the recommended project features
adjacent to the lower lake. Approximately 45 acres of forest would be
cleared for the transmission line. Trees that threaten the transmission
line ~ould be selectively removed on an estimated additional 75 acres.
Adverse impacts to forest and wetland communities would be minor due to the
relatively small acreage affected by the project.
Project related habitat alterations would favor black-tailed deer, black
bear, and blue grouse (Dendragapus obscurus) during nonwinter months. High
snow accumulations may preclude use of clearings during winter. While
clearing of old growth forest would result in a small loss of black-tailed
deer winter habitat, increased mortality is not anticipated. Losses of old
growth forest would be potentially more detrimental to those wildlife
species that show greater specialization to this unique habitat for
survival. Displacement of some members of these species would be expe·cted,
although it is unknown whether adjacent habitats could absorb these
individuals without causing stresses due to competition. Additional roads
considered as alternative forms of access would result in much .greater
losses of wi ldJ ife habitat compared to the recommended plan.
The overall water temperature regime of the lower lake is not expected to
change significantly from project related discharges of 4°C water derived
from the upper lake. However, local water temperature changes at points of
upwelling along the west shore of the lower lake would occur, resulting in
negative impacts to sockeye salmon. These impacts could be mitigated
through careful placement of the powerhouse and tailrace and by
manipulating the temperature of tailrace waters. Other species of resident
or anadromous fish would not be significantly affected by the proposal.
Overall water quality in the Mahoney Lakes system should not be
significantly affected by the proposal. The It/aterfall on Upper Mahoney
Creek would be eliminated by the project and, to many, this would represent
a significant esthetic loss. Negative social or economic impacts related
to the proposed hydropower project are not anticipated. Residents of
Ketchikan would benefit because the proposed project would supply power at
a lower cost per kilowatt-hour than diesel generators of comparable
capacity. The project would have no impact on cultural resources.
EIS-v
Public involvement for the feasibility study was initiated in 1975 and has
continued sporadically to the present. To facilitate the identification of
environmental concerns, scoping was conducted during the late 1970's and
again in early 1982. The U.S. Forest Service has been designated as a
cooperating agency for the Mahoney Lakes study, primarily because of their
management responsibilities for lands affected by the proposal.
The proposed project would involve a dis~harge of fill material into waters
of the United States and adjacent wetlands and would, therefore, be subject
to the requirements of Sectton404 of the Clean Water Act. The information
required to adequately address the effects of such discharge, within the
meaning of Section 404(r) of the Clean Water Act,inc1uding consideration
of the guidelines developed under subsection 404(b)(1), has not yet been
developed. This document is considered adequate for the current stage of
project planning; additional information will be developed to comply with
Section 404 during further engineering a~d design studies and prior to the
. actual discharge of fi1·1 m~teria1. Full compliance with Executive Orde~
11990--Protection of Wet1ands--wi11 be achieved upon completion of the
404(b)(1) Evaluation. A preliminary determination indicates that the
requirements of Executive Order 11988--Floodplain Management--are not
applicable to the current project proposal. The proposal is consistent
with the Alaska Coastal Zone Management Plan.
EIS-vi
T'J .....
/l
I c:: .... ......
Table EIS-l
Relationship of Plans to Environmental Protection Statutes and Other Environmental Requirements--
Mahoney Lakes Hydropower Project
Federal Statutes
Archaeological and Historic Preservation Act
Clean Air Act
Clean Water Act
Coastal Zone Management Act
Endangered Species Act
Estuary Protection Act
Federal Water Project Recreation Act
Fish and Wildlife Coordination Act
Land and Water Conservation Fund Act
Marine Protection Research and Sanctuaries Act
National Environmental Policy Act
National Historic Preservation Act
River and Harbor Act
Watershed Protection and Flood Prevention Act
Wild and Scenic Rivers Act
Compliance Status
Full compliance
Full compliance after EPA review of EIS
Section 404(b)(1) Evaluation will be completed as detailed
design information becomes available during
post-authorization studies; NPDES permit reauired from EPA
prior to construction
(See State requiremerits)
Full compliance
Full compliance after Dept. of Interior review of EIS
Not applicable
Full compliance
Not appl icable
Not applicable
Full compliance after Record of Decision is signed
Full compliance
Not applicahle
Not applicable
Not applicable
..... ..... ....
Executive Orders and Memorandums
Floodplain Management (11988)
Protection of Wetlands (11990)
Environmental Effects Abroad of Major
Federal Actions (12114)
Analysis of Impacts on Prime or Unique
Agricultural Lands in Implementing NEPA
State Requirements
Clean Water Act-Section 401
Coastal Zone Management Act
Required Entitlements
U.S. Forest Service
Cape Fox Native Corporation
Table 1 (cont)
Compliance Status
Not applicable
Full compliance after Section 404(b)(1) Evaluation
Not applicable
Not applicable
Full compliance after State issuance of Water Quality
Cert ifi cati on
Full compliance after State concurs with determ1natio~ that
project is consistent with t~eir coastal management plan
Full compliance after Forest Service reviews final plans
and approves construction
Acquisition of lands now owned or controlled by Cape Fox
Native Corporation must be negotiated prior to project
construction
Table EIS-2
Effects of the Tentatively Recommended Plan on Resources of Principal National Recognition
Types of Resources
Air Qual ity
Areas of Particular Concern
Within the Coastal Zone
Endanqered and Threatened
Species/Critical Habitat
Fish and Wildlife Habitat
Flood Plains
Historic and Cultural
Properties
Prime and Unique Farmland
. Water Quality
Wetlands
Wild and Scenic Rivers
Principal Sources of National Recognition
Clean Air Act, as amended (42 U.S.C. 1857h-7
et seq.).
Coastal Zone Management Act of 1972. as amended (16 .
U.S.C. 1451 et seq.).
Endangered Species Act of 1973, as amended (16
U.S.C. 1531 et seq.).
fish and Wildlife Coordination Act (16 U.S.C.
Sec. 661 et seq.).
Executive Order 11988, Flood Plain Management
National Historic Preservation Act of 1966, as
amended {16 U.S.C.Sec 470 et seq.).
CEQ Memorandum of August 1, 1980: Analysis of
Impacts on Prime or Unique Agricultural Lands in
Implementing the National Environmental Policy Act.
Clean Water Act of 1977 (33 U.S.C. 1251 et seq.)
Executive Order 119g0, ProtectiQnof Wetlands Clean.
Water Act of 1977 (42 U.S.C. ~857h-7, et seq.)
Wild and Scenic Rive~s Act, as amended (16 U;S.C.
1271 et seq.).
. Measurpment of Effects
No effect.
Not present in planning
area.
Not present in planning
area.
Forest and wetland habitat.
Approximately 18 acres lost
. and 45 acres alter~d.
Alpine habitat •. ·
Approximately 19 acres lost.
Aquatic habitat.
Less than 1 acre lost.
No effect.
Not present in planning area.
Not present in planning area.
No effect.
Less than 10 acres wetland
lost.
Not present in planning area.
1.0
2.0
3.0
4.0
5;0
6.0
7.0
DRAFT ENVIRONMENTAL IMPACT STATEMENT
Table of Contents
SUMMARY
NEED FOR AND OBJECTI VES OF ACTION .
1.1 Study Authority
1.2 Public Concerns
··1.3 Plannfng Objectives
ALTERNATI VES
2. 1 Plans El iminated ·from Further Study
2.2 No Action Alternative
2.3 Plans Considered in Detail
COMPARATIVE IMPACTS OF ALTERNATIVES
3.1 Tentative1y Recommended Plan
3.2 Alternative Features
3.3 No Action
AFFECTED ENVIRONMENT
4.1 Environmental Setting
4.2 Significant Resources
4.2.1 Coastal Forest
4.2.2 Wetlands
4.2.3 Wildl ife
4.2.4 Fisheries
4.2.5 Water·Quality
4.2.6 Socioeconomic and Esthetic Resources
4.2.7 Cultural Resources
ENVIRONMENTAL EFFECTS
5.1 Coastal Forest
5.2 Wetlands
5.3 Wildlife
5.4 Fisheries
5.5 Water Quality .
5.6 Socioeconomic and Esthetic Resources
5.7 Cultural Resources
5.8 No Action
PUBLIC INVOLVEMENT
6.1 Requ1red Coordination
STATEMENT RECIPIENTS
EIS-x
Page
EIS-ii
EIS-l
E IS-l
E IS-l
. E IS-l
EIS··l
EIS-l
EIS-3
EIS-3
EIS-5
EIS-5
EIS-6
EIS-6
EIS-7
EIS-7
EIS-8
EIS-8
EIS-9
EIS-10
EIS-ll
EIS-12
E1S-13
EIS-13
EIS-13
EIS-14
EIS-15
EIS-1S
EIS-18
EIS-22
EIS-23
EIS-23
EIS-24
EIS-24
EIS-24
EIS-25
8.0
9.0
LIST OF PREPARERS
INDEX
[IS-26
[IS-27
EIS-27 10.0 LITERATURE CITED
... Table EIS-l
Table ElS-2
Tables
Relationship of Plans to Environmental EIS-vii·
Protection Statutes and Other Environmental·
Requirements-.:.Mahoney Lakes Hydropower Project
Effects of .the Tentatively Recommended E IS-i x
·Pl~n on Re~ourceiof Princip~l National
Table EIS-3
TableEIS-4
Figure EIS-l
. Figure EIS-2
Figure EIS-3
APPENDIX EIS-A
APPENDIX EIS-B
Recognition
Selected Water Discharge Data for the EIS-20
.. M~honey Lakes System
. .
.' . '. .
U.S. Fish and Wildlife Service· EIS-25
. Recommendat ions and Alaska Di strict Responses
Figures
Location of Ketchikan and Vicinity
Location of Mahoney Lakes
Proposed Project Features
Appendices
EIS-iii
EIS-; v
E 15-4.
CORRESPONDENCE FROM INITIAL
SCOPING ACTIVITIES (1975-80)
CORRESPONDENCE FROM FINAL
. SCOPING ACTIVITIES (1982)
APPENDIX EIS-C· U.S. FISH AND wilDLIFE
SERVICE COORDINATION ACT
REPORT (1982)
EIS-xi
DRAFT ENVIRONMENTAL IMPACT STATEMENT
Proposed Hydroelectric Development on the Mahoney Lakes System near
Ketchikan, Southeast Alaska
. .
1.0 NEED FOR AND OBJECTIVES DF ACTION·
1.1 Sturly Authority
The proposed Mahoney Lakes hydropower development is being studied in
partial response to a resolution adopted by the committee on public works
of the United States House of Representatives on 2 December 1970, under the
title of Rivers and Harbors in Alaska~ Furthermore, Senate Report 93-1032,
dated 26 July 1974, urged the Corps to focus attention on the study of
hydropower development in Alaska.
1.2 Public Goncerns
If energy demand in the Ketchikan area continues to grow at its present
rate, additional generating capacity will be needed in the early 1990's~
Residents of Ketchikan have expressed a desire to reduce their dependence
on diesel generated energy due to rapidly escalating fuel costs. A clean,
renewable source of energy, such as hydropower, is an attractive
alternative.
1.3 Planning Objectives
The proposed hydropower development at the Mahoney Lakes site is designed
to supplement long term electrical energy needs of the Ketchikan area.
This is consistent with national goals that encourage the conservation of
nonrenewable resources and promote t~e development of renewable sources of
energy. Equally important objectives are to avoid, minimize, or mitigate
adverse environmental impacts associated with the project.
2.0 ALTERNATIVES·
2.1 Plans Eliminat~d from Further Study
Several alternatives for prbducing energy in the Ketchikan area have been
explored, such as:
Restricting community growth
Coal fired thermal generation
Natural gas fired turbines
Diesel generation
Nuclear generation
Geothermal generation
So 1 ar generat i on
Wind generation
Tidal g~neration .
Wood fired thermal generation
Regionalintertie system
Solid waste fired generation
Lake Grace hydropower
Rejection of these alternatives was based on economic, environ~ental,
technological, transportation, climatic, supply, and political.
considerations. Diesel generation, a regional intertie, and Lake Grace
hydropower have received greater attention and a brief discussion of their
associated environmental impacts is warranted.
as
Diesel Generation--The additibn of di~sel generating capacity in the
Ketchikan area would perpetuate the problem of escalating energy costs
associated with the use of fossil fuels. A direct impact of coritinued
operation of diesel plants is degradation of air quality. The
identificatibn, ext~action, refinement, and transportation of fossil fuels
can also lead to serious environmental problems. The feasibility of
continued use of d~esel gen~rators is further addressed in subsequent
di~cussions.
I Regional Intertie~-The engineering, economic; and environmental feasibility
of connecting the electrical systems of several Southeast Alaska
communities is currently under study by the Alaska Power Administratipn.
The goal of the intertie would be to utilize available hydropower at
certain locations while reducing dependence on fossil fuel generation in
:btherareas (Teshmont Consultants Inc., 1982). Also, a large developing
mining operation (Quartz Hill) near .Ketchikan will have a substantial
energy demand. Meeting this demand could be facilitated by construction of
a regional transmission i~tertie.
Environmental impacts associated with overland portions of the transmission
line may include wildlife habitat alteration, avian mortality resulting
from collisions, disruptibn of raptor nesting behavior (particularly bald
eagles), electrocution of raptors, erosion and resulting sedimentation of
lakes and streams, and esthetic considerations. Submarine portions of the
line may produce electrical and magnetic fields that could affect fish
migration. Additional potential impacts of a submarine cable include
ecosystem disturbances during construction and interference with fishing
operations and navigation instruments~
Lake Grace--The Lake Grace system, located about 32 air miles northeast of
Ketchikan on the east side of Revillagigedo Island, was evaluated by the
Corps as a potential producer of hydroelectric energy. Figure 8 of the
main report shows the location of Lake Grace. Project features would
include a dam on Grace Creek about 1/2 mile below the outlet of Lake Grace,
a lake tap, underground power tunnel, surface penstock, and a powerhouse·
located on Grace Creek abo~t 1 mile upstream from the mouth. The plan also
includes dock facilities, housing for operating crews, a 4-mile service
road connecting project features to the dock area, and a 20-mile
transmission line between the powerhouse and the Carroll Inlet intertie.
A significant project impact would be the loss or reduction of pink and
chum salmon production in Grace Creek due to changes in the thermal regime
belo~ the powerhouse. Releases of cold water from the powerhouse during
late summer could adversely affect spawning and egg development. In
addition to the aquatic impacts, significant destruction or alteration of
terrestrial wildlife habitat would ~esult from the Lak~ Grace project.
Filling of the reservoir would inundate about 100 acres of bottomland open
meadow habitat and about 470 acres of mixed conifer old growth forest.
Another 370 acres of old growth forest would be altered by construction of
the transmission line. Additional habitat would be lost through
construction of the service road, dock, housing, .andother facilities.
Affected wildlife would include, but would not be a limited to,
black-tailed deer, black bears, small furbearers, and various species of
waterfowl and songbirds. .
E1S-2
Because of favorable economics, the Lake Grace project is the designated
National Economic Development (NED) plan. However, in.additioIT to the·
significant environmental problems, the Grace Lake project would be located
within the Misty Fjorrls National Monument, a designat~d wilderness area
under the AI aska Nat i ona 1 Interest Lands Consel~vat i on Act (ANILCA) (P.L
96.,.487, lJecember 2,1980). A development of this scope, without .
Presidential and Congressional approval, would be incon~istent with ANILCA
and the ~roject is, therefore,. not recommended.
2.2 No Action Alternative
Present trends suggest cont i nued moderate popul at i on growth for Ketchi kan.
A corresponding rise in energy demand is expected. In the past, the cost
of energy generated by hydropower plants h~s been significantly less (per
kilowatt hour) than that generated by diesel plants. However, high iriitial
cap ita 1 investment precludes the community of Ketchikan from developing
nearby hydropower sources. Without government action it can be assumed
that Ketchikan will continue to supplement its energy needs through the
addition of diesel gen~ratingcapacity. Future costs of diesel generated
energy are expected to rise sharpli as the supply of oil diminishes.
Therefore,t~e economic feasibility of continued reliance on diesel by
Ketchikan is questionable.
2.3 Plans Considered in Detail
If only short term costs are considered, diesel generation is economically
superior to Mahoney Lakes hydropower development. However, if projected
diesel fuel cost escalations are taken into account, Mahoney Lakes
hydropower would be more cost effective over the long term. The proposal
is also responsive to the maintenance of environmental quality. Therefore,
the Mahoney Lakes project has become the tentatively recommended plan.
The initial concept for hydropower development of the Mahoney Lakes system
has not changed signifitantly throughout the planning process and only one:
plan has evolved. This is due primarily to the physical characteristics of
the site and associated inherent limitations of hydropower development.
Various alternatives to specific features of the tentatively recommended
plan have been examined and are discussed in this secti6n.
The tentatively recommended plan for hydropower development on the Mahoney
Lakes system wou.ld provide lS.O-MW installed capatity. Project features
are shown in Figure EIS-3.
The proposal would involve tapping intb the east side of the upper lake at
a :)oint 225 feet below its existing surface. Penstock length would be
5,370 feet. Other tap depths were. considered but the 22S-foot-deep lake
tap is recommended because it would optimize project operation. The
recommended penstock would be 36 inches in diameter and run for 4,000 feet
underground. A 10~foot-wide tunnel would be constructed to provide access
to the penstock and intake. After emerging from the tunnel, the penstock
would continue downhill for 1,370 feet before entering a powerhouse near
Mahoney Lake.
. E IS-3
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MAHONEY LAKE
EL. 84'
PLAN
4~ 0 SCALE IN FEET
~-=,-_..!2400~~ao~O~ 1122'00
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ACCESS ROAD
GEORGE INLET
SEAPLANE FL
D
OAT
OCK ,
~~~NSMISSION
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"()P()6RAPHY BY . ~RVK:E 197" AE~7AL MAPPING FROM ND ASSOCIAT. PHOTOGRA u.s. FOHEST
BASED ON US:: HORIZONTAL 7;BY RW BECK QUADRANGLE MAP. VERTICAL CONT. :s. "ROL
PR PROPOSED
OJECT FEATURES
r.IIIP.I IiiIiiI ':~ S RIVERS A _DiIIrict OUTHEAST HYD~~;~:~~RS IN ALASKA RIC POWER INTERIM
The recommended form of access to the penstock tunnel portal is by
helicopter. A heliport would be constructed near the portal. Other
alternatives considered include construction of a road, construction of a
tramway, or skidding materials to the portal. These options are not
recommended for engineering, economic, and environmental reasons. Tailings
from excavation of the penstock tunnel would be discharged adjacent to and
north of the tunnel portal.
The preferred powerhouse site would be near the southwest edge of the lower
lake. An alternative site is located approximately 1,500 feet upstream
from the lower lake and would be nearer to the stream channel. This site
is not recolmnended because it would require the penstock to cross an area
of high avalanche potential, and the powerhouse would be in the floodway.
The recommended tailrace design would direct water back to the vicinity of
Upper Mahoney Creek upstream from the lower lake. This would serve to
initi~ate the disruption of flows in Upper Mahoney Creek due to the project.
lIn optional tailrace design ~'iould channel I/ater over artificial spawning
beds before it ItJould reach the lower lake. This could increase fish
production in the lower lake/stream system. Further informdtion regarding
mitigation and enhancement measures is contained in the section dealing
with impacts to fish.
A camp area, containing storage and maintenance facilities, staging area~,
and living accommodations for project personnel, would bE located hetween
the lower lake and George Inlet. The tentatively recommended plan also
cal is for a dock and seaplane float in George Inlet to provide sit~
acc~ss. The dock would be connected to the camp and powerhouse by a gravel
service read about 1.4 miles in length within a 50-foot right-af-way.
Suitable gravel for road construction could be taken from Upper ~ahoney
Creek above the powerhouse site. Electricity would be conveyed tu a
SUbstation at Beaver Falls via a 4.9-mile, 34.S-kV transmission line. The
reco~nended transmission line corridor would roughly parallel George Inlet
within a 75-foot right-of-way.
Construction of a road between Beaver Falls and the proposed camp area
would provide alternative access to the site. The route would probably
parallel George Inlet. However, this option is not recommended because of
the high costs and environmental concerns.
A 2S-foot binwall type dam constructed at the outlet of the upper lake is
tentatively recommended. Access to the damsite would be accomplished by
helicopter. Two alternative dam heights of 50 and 75 feet have been
reviewed but are not recommended because they would require concrete
gravity or rockfill dams that are not cost effective. Additional
information regarding the tentatively recommended plan can be found in the
main report.
j.O CUMPARATIVE IMPACTS OF ALTERNATIVES
3.1 rentatively Recommended Plan
Coastal Forest and Wetlands--The tentatively recommended plan would destroy
or alter an estimated 63 acres of land that is a mixture of forest and
EIS-S
wetland. Selective removal of trees may be necessary on approximately 75
additional acres.
Wildlife--While some displacement of resident wildlife would occur during
constn'ction , the project would not r'esu-It 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 Qualiry--MaJor impacts to water quality of the Mahoney Lak~s systpm
are not antiEipated.
Socioeconomic and Esthetic Resou r ces--Slight social and economic growth in
the KeECh'ik-ana~~ealnay occur dur'ing 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
watel~f all.
Cultural Resources--fhere are no significant historic or archaeological
s i t"es 'lear the proposed proj ect site.
3.2 Alternative Features
Coastal Forest, Wetlands, and Wildlife--Substantially greater acreages of
forest (also including alpine areas), and to a lesser extent wetland, would
be destroyed or a:tered 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 g~eater storage capabilities. Negative impacts to forest and
wetland ecosystems and losses of wildlife habitat would be much more
significant if the~2 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 alternativ~ tailrace
design that would include artificial spawning beds could potentially
\ improve fish production in the 10wer lake.
" ~ar~r Quality, Socineconomic, Esthetic) and Cultural Resources--Alternative
feature--impacts to these four resources wou 1 d be simi 1 ar to potent i a 1
effects of recommended features. However, a road connecting Beaver Falls
to the project slte would adversely affect water quality and esthetic
va! lJes to a ')n~ater' extent than the recommended p loil1.
3.3 No Action
If the proposed project is not constructed, the condition of existing
resources near the Mahoney Lakes system would not change.
E1S-6
4.0 AFFECTED ENVIRONMENT
4.1 Environmental Setting
The Mahoney Lakes, site of the proposed project, are located near the
southern boundary of Southeast Alaska on Revillagigedo Island about 6 miles
from the City of Ketchikan. Revillagigedo Island is part of the Alexander
Archipelago, also known physiographically as the Coastal Foothills
province. This chain of islands is characterized by high mountains that
are deeply incised by fjords, bays, and inlets.
Upper Mahoney Lake is 1,954 feet above sea level and is fEd by two smaller
lakes located at about the 2,300-foot level. These lakes are frozen most
of the year and precipitation at higher elevations is usually in the form
of sno~l. Upper Mahoney Creek (also known as Falls Creek) drains fr'ol1l the
northeast corner of Upper Mahoney Lake and drops dramatically down a
spectacular falls before y'eaching Mahorley Lake at an elevation of 80 feet
above sea level. Several smaller streams fed primarily by runoff from the
surrounding watershed also drain into the lower lake. Mahoney Lake is ice-
free except during severe winter weather. George Inlet ultimately receives
all water draining from Mahoney Lake via Mahoney Creek (Figure EIS-3).
A maritime climate prevails in the region and is characterized by mild
winters, cool summers, and high precipitation. In Ketchikan an average of
154 inches of precipitation falls annually, including 33 inches of snow.
Temperatures range from an average of 34°F in January to 59°F in August.
Prevailing winds are from the south/southeast. The growing season is long,
beginning in early May and lasting until early October. Local ciimatic
patterns are strongly influenced by the mountainous topography of the
region.
Floral communities in Southeast Alaska are relatively productive and are
characterized by high species diversity. Coastal forests, dominated by a
western hemlock (Tsuga heterophylla)-Sitka spruce (Picea sitchensis)
association, are primarily "old growth" with the average age of a stand
about 200 years. Interspersed within the forest are bogs, which are
wetland ecosystems commonly referred to as muskeg. A third distinct
vegetative community is found above timberline (2,500-3,000 feet) and
contains plants adapted for life in an alpine environment. Altitudinal and
topographical variations are primarily responsible for influencing the
development of plant communities.
Black-tailed deer and black bear are two of the more common large mammals
found on Revillagigedo Island. Numerous smaller mammals, including aquatic
furbearers, are common. The island contains rich avifaunal communities
with all major groups, including raptors, waterfowl, shorebirds, and
songbirds, well represented. Bald eagles, one of the more conspicuous
species, are common along coastlines where they nest. In general, many of
the birds and mammals indigenous to Southeast Alaska are specially adapted
to the old growth forests of the region.
Of the five species of Pacific salmon that spawn in Alaska, only chinook
(~ tshawytscha) are absent from the waters of Revillagigedo Island. Pink
EIS-7
salmon are most important commercially, but are also popular with
recreational fishermen, along with coho salmon {O. kisutch). Trout and
Dolly Varden char ay'e locally abundant near Ketchlkan.
After w~ite settl~ment, growth in the Ketchikan area was primarily
associated ;·dth cO"1mercial salmon fishing. In the early 1960's, a major
forest products industry began to develop in the region. Subsequently,
commercial fishing diminished in importance due to a dec-line in salmon
stocks resulting from overfishing. This trend may be reversing, however,
with the advent of careful fisheries management. The wood products
industry, primarily wood pulp manufacture, is the largest commodity
producing employer in the vicinity of Ketchikan. GOvernment emp10ys the
largest segment of the population in the area. Tourism is light, due
mainly to the cool, wet climate. Access to Revillagigedo Island is only by
boat or plane, wnlch underscores the importance of seaports to local
COrnmUnltles. Additional growth in the area is expected with the projected
development of a major molybdenum mine 43 miles from Ketchikan.
4.2 Significdnt Resources
4.2.1 Coastal Forest
The forested areas near the lower lake are part of a larger forest
ecosystem that extends along the Pacific coast from northern California to
Cook Inlet, Alaska. Roughly 95 percent of Southeast Alaska's forests are
. old growth (Meehan, 1974). This term is usually applied to mature
coniferous stands of the Pacific Northwest that have not been disturbed to
a great extent by natural (E.g., fire) or human (e.g., logging)
,influences. The average age of a stand in Southeast Alaska may exceed 200
years, with individual trees reaching ages of l~OOO years. It is this
unique old growth character, a rarity in most of the United States, that
attaches special significance to this resource.
The forests generally appear to have a ragged te~ture due to differences in
age, species, and vigor. A high number of dead top~ and snags is
characteristic. The forest community between timberline and sea level is
dominated by a western hemlock-Sitka spruce associaton. This is true for
the forest near the project site. Harris and Farr (1974) list the species
composition of these stands as averaging 73 percent western hemlock and 12
percent Sitka spruce, with lesser percentages of western red cedar (Thuja
plicata) and Alaska cedar (Chamaecyparis nootkatensis). Mature trees
usually range from 100 to 150 feet in height and may be 2 to 4 feet in
diameter. Intermediate plant communities that combine elements of forest
and bog grow near the forest edge. Western red cedar and Alaska cedar
become more prevalent, and mountain hemlock (T. merten~iana) and shore pine
(Pi nus ~:9~tor:_t_~) may start to appear. -
Understory vegetation such as salal (Gaultheria shallon), blueberry
(Vaccinium spp.), huckleberry (V. parvifolium), rusty menziesia (Menziesia
ferrugine.~)~-talle\' shrubs, o:1d-young conifers can be quite dense. Western
hemlock is more shade tolerant than either the spruce or cedars and is,
therefore, probably represented to a greater degree in most understories.
Numerous vascular plant species are found in the herbaceous layer, although
tI5-8
mosses, such as Sphagnum spp., are often dominant. Large quantities of
fallen timber in various stages of decomposition also contribute to the
crowded understory conditions.
The timberline on Revillagigedo Island is at about 2,500 feet. Although
the surf:ce of Upper Mahoney Lake lies belo~ ~his elevation, the
surrounding terrain r'is~s sharply. Scatte('ed and stunted conifers,
particuLil~ly mountain he,l11ock, oCcur at. higher' elevations. SUbstantial
forest development is precluded around Upper Mahoney lake, however, and
plant communities reflect an alpine environment. Interspe~'sed with rock
outcroppings and rubble are dwarf vat'ieties of w'j i10w (~!DL~ .?2.2..) and
blueberry, various heaths, grasses, and otner low plants.
Among the more important factors responsible for forest development near
the f'1ahoney Lakes system are cl imate,alt itude, ~,lDW:, ana soi 1 drainage.
Species composit-ion, distribution, and density I'Jithin a community are
illtricately l'jqked to these influences. SIKces::;;oi1a'l development and the
concept of J climax community are also affected.oy the above parameters and
should be exarn~ned because of their imolications to wiidl ife. A discussion
of successional changes resulting from' disturbances to the forest community
will be presented in a 1a~:er section dealing v~'ith effect:> of the pr'oposal.
4.2.2 Wetlands
Rog, or mUSkeg, is the Gnly type of wetland found near the project site.
The open bogs may range from red to yellow-green in appearance and are
usually dominated by a moss-sedge-ericdceous shrub ass0cation. Scattered,
small shore pine and Alaska cedar may also be present. As the forest is
appY'oached, the size of shot'e pine increases, and Western red cedar and
mountain hemlock usually appear. Blueb~rry, huckleberry, and rusty
rnenziesia are common in the understory of forested bogs. Greater sunligllt
penetration and warmer soil temperatures often result in higher plant.
diversity in the bogs compared to the spruce-hemlock forests. In gencr~1,
however, bogs are characterized by low productivity, low plant biomass, a
slow and incomplete turnover of organic matter, (lnd a storage of nut"'ients.
Wildlife use of these areas is low, although during late summer and ~arly
fall, berry prodllction may drav>' large numbel's of birds and mammals.
A peculiar aspect of many of the bogs in Southeast Alas%a is their raised,
rather than depressed. surfaces. The combined influences of high precipita-
tion and cool temperatures result in large accumulations of organic matter
that serve to retard drainage. Compact glacial tin under'lying thf.' surface
organic layers also prevents soil drainage. Apparently, tne water r~tention
capabilities of the accumulated organic matter is so great, that bogs can
form raised surfaces or develop on moderate slopes. The above conditions
have i)een used to explain the theory that bog communities are the cl i:ndX
Sl!cu~ssiona1 stage in Southeast Alaska. Zacn (1~:S()) spl~c;lat~;s that the
forests may slowly be J~teriorating and are bei~y replaced by bog
ecosystems.
Because of the elevated wetlands and adjecent mountainous topography, flood
plains are small. During periods of intense rUnoff, flooding occurs along
Upper :~arlOney and Mahoney Creeks in nanow bands alar'g stream mdrgins and
EIS-9
I
I
in braided areas. Because these areas are small, they play only a minor
role in maintining the integrity of aquatic ecosystems :and provide only
minimal floodwater retention or dissipation benefits.
4 . 2. 3 l,j 11 Q 1 if e
Wildlife populations near. the Mahoney Lakes are well adapted to their
respective habitat3 and, for most species, recent significant increases or
declines have not been reported. In general, population density is. limited
by habitat maturity. This is of particular importance in the old growth
coastal forests. Extreme topographical changes also influence habitat
. ava~lability. Except during severe winter's, weather is usually llOt
limiting in Southeast Ala.ska due to the mild maritime climate. Diseases
and parasites have not been major factors in the regulation of
populations. There are few carnivorous predators on Revil1agigedo Island.
Predator-prey systems have apparently reached a balance since populations
of each are relatively stable. Human influences have been minimal because
regional population levels are low and access to remote areas is limited.
The moderate weather in the area favors black-tailed deer, which are common
near the study area. During the spring and summer, black-tailed deer
prefer muskeg edges and alpine habitats due to higher quality forage in
those areas (Meehan, 1974). As winter approaches, deer are forced down to
lower elevations by heavy snows and seek shelter in the mature forests
along coastlines. During severe winters, deer survival is linked to the
availability of mature forest and beach habitat. A key winter range for
black-tai led deer has been identified a"long George Inlet immediately north
of the lower lake (Martinson and Kuklok, undated).
Black bears are present, although not particularly abundant, in the study
area. Usually bears prefer forest openings with fruit producing shrubs and
herbs, lush grasses, and succulent forbs. Forest openings are limited in
the study area except for muskegs, which may provide suitable habitat. In
late summer and early fall, bears may concentrate along streams to feed on
spawning salmon. Partially eaten salmon carcasses have been observed along
Mahoney Creek. However, salmon are considered incidental in the black
bears' main diet of berries during late summer and fall. Major
concentrations of black bears have not been identified within the influence
of the proposed project.
Wolves are found on Revillagigedo Island and population levels are linked
to the density of their chief prey species--black-tailed deer. Specific
information on wolves near the Mahoney Lakes system is not available.
Beaver (Castor canadensis) cuttings have been found along the shorelines of
the lO,tJer--la-ke,-----afthough ·population levels in the area are not known.
Marten (Martes americana) are probably present in the mature stands of
hemlock a:-r~(rspY'·ljce.-rfl,ink {Mustela Vlson) and river otter (Lut.ra
canadens is) usua lly OCCLlI" a-1ongbeaches and streambanks and it is 1 ike 1y
that these species are found within the study area. Several other small
mammal species are ~e~orted to occur in the vicinity.
Bald eagles frequent coastlines in search of fish, an important item in
their diet. Eagles prefer to nest in a mature spruce within several
hundred feet of a shoreline. Three nests have been identified to the north
US-10
of the project are,l (rvla:~tinson and Kuklok, undated). Valious other species
of raptors can also be found in the coastal forests near the project site.
Glue grouse dild. spruce grouse (CanachHes canadensis) have been i"epor"ted
within the study area. In the ~~mmer and fall. grouse, particularly olue
grouse, are found near timberl ine feeding on berries and insects. During
t~e wintpr they usually descend to lower ~le~at~0ns where thAY subsist on
th(~ buds nnd needles of conifers. Rock ptdF':ni~an (.!::.~opus muj;usJ an::] wi 110w
ptarmigall (L. leucur"us) are reported tJ occur ir: the area. Ptarlnig3n are
usually found at or·-abovetirnbey·line. vJatey'fol'/-1 use Geo\"ge Inlet pdmarily
for resting and feeding during spring and fall migrations, although a few
individuals may remain in these waters th~oughout the winter. The Mahoney
Lakes system does not attl"dct \,'aterfowl due to th;:; 1 acf'. (iF sTii:able habitat.
A variety of songbird species can be found i~ the forests and muskegs
adjacent to the lower lake. Although matute for:::'t', are usually not noted
for high avian diversity. the old growth nature of the coastal forests in
'Southeast Alaska pf'ovid2S a t:niqu,::, habitat. Tk:' Ul1W;uoi ly hi~~h num8er of
snags, or dead trees, att~acts a variety of cavity nesting birds. 1n
addition, snags are used for perching. ~2eding, and roosting. Many ~pecies
have adapted to the specialized conditlons present in an old qrowth stand
and are seldom seen in other habitat types; examples are the ~orther~ .
three-toed woodpecker (Picoioes tridactylus) and Townsend's warbler
(.Q end 1"0 i __ 0~ t m~ send U (BiJTI,-19nn-. -----
The U.S. Fish dnd Wildlife ~ervice and National Marlne Fisheries Se~vice
. were requested to investigate the presence of threatened or endan~or~d
species near the Mahoney Lakes system. Their responses indicat~d that they
were no[ aware of any threatened or endangered species within the influence
of the proposed p~oject.
4.2.4 Fisheries
Coho, P,'l" C:h:;r,', ond sockeye salmon have been n~port::;d in the r~Jhcney
Lakes system. Coilos dre apparent: ly rare and thei'r numbers have not been
documenteci. Escapement counts for pinks and chums in f/iailofH:'Y Cree:: are
available back to 1943. The most recent count was conducted 011 11 Octoher
1974 dndrepOl't-::o 1,000 pin~ and 1,000 churn salmon. The Mahoney '_,ekes
system is riOt used fo~' reat'ing habitat by these L'10 species; pink 2nd churn
fry migrate to madne \~aters ~i1imediately after f:fI\en;lng from str'(~am gravels.
Sockeye salmon, both anadrorJ1oJs dnd resiaent ferns, a"e pr'esent in the lovy'er
lak·=. Young anadromous sockeyes normally rear -in a fr,,,,,';fMater lakE: for 1 to
2 years before outmigrating to a marine environment for the next ~taqe in
their life cycle. In most cases, adults spawn in streams flowing into or
out of a lake and. after hatching, fry swim to the lake to r~ach rear~ng
areas. In the Mahoney Lakes system, sockeyes do ~ot sparin ~n Mahoney Creek
[Jf;CdUS2 Uif~ v-io1ent nows would prevent fr'y f"(Hi moving L,)st\'(-~am tc t.h",
laK~. Trijutaries flowing into the lake ~lso are not used by s0ckeY0s
because of tneir imp~'edictab-ie flo~'/s. The stn::('tlni)eos of thfse t,'il)utanes,
particul,3rlj IJpl!'~l" r,jah;"n2Y Creek, a're often or,:; in thc;~ li)\'Jer reach(~s, and
~'iatet' apparf;ntly flows under-ground throuqh f;~~!hly penT:cable 9(';,}ve1s. Water
from these stre~ms ofteG cischdrges into the lower lake witnoct resJrfacing.
In the lower 1 ake, sockejes have been "bserv!2,j ::;pa~~r,i rig onlY near the
'ri'2stenl shor'? Itinere t'lere i'S u;Jwel-::ng detivpd !:,r~ni,11' 1./ 'fro;;! UDDer ;"1ahonC!,Y
Cr-eek.
f.IS-l:
fhe spawningimpu Ise in laKe sockey~s is apparently triggered by the
temperature of water upwelltng from gravels near shorelines. Proper egg
cleve] opmenti s Ii nkeej to the tempet'ature of up\'Je 11 i ng \'Jater and currents
created by upwelling processes. Initially, water temperatures should be at
or above 6 u C for optimum development of eggs. Colder temp2ratures can be
toleratrd only during later stages of embryonic development (Combs, 1965;
J. l)ailey, ,:;ii:;or:al f'~arine r-:isileries Service, pe(So:lJI clYilrnunication). As
stated, upl'i211 i rig Jrocesses a -long the western shore of the lower 1 ake are
caused ~)!"i!nar-i:v Llj surfaCe I'jaters from Upper ;'~ahonc:l .Creek that have
percolated through delta gravelS. Temperatures at points of upwelling are
a close ref1~ctiun of streain tGrnperatures. ~\d,ter temoe,'atures measured at
the mouth of Upper Mahoney Creek in September when sockeyes were observed
srawning were lO~C.
Aerial counts on 14 September 1982 totaled 200-300 sockeyes in the lower
u!ke. tn addition, l()0..,2UO sockeyes wert'; observed r:lGvil1g UD 1\llahoney Creek
on t.he same d,jce" This indicates that for 1982 the minirl'im number of adult
anadrO~0US sockeyes using the M~honey ~akes system is eS[lmated between
300-500. ?opu-Iation size and the exact lOCation of spawning activity
. (alon9 the ~",ester'n shu\~(~ of the lake) had not heen confinTied before
14 September 1982. The 1982 counts indicated a larger run than what was
previously thought to occur and prO'iidl~d evidence that the system could
potentially support larger numbers of sockeyes. This is consistent with
historical records that show sockeye runs up into the lower lake have
fluctuated from a few hundred to se~eral thousand fish (Martin, 1959).
The system also sJpports limited populations of Uolly Varden and possibly
rainbow (Salmo qairdneri), steelhead (sea-run rainbows), and cutthroat
t\~out \~a-'Fnu-c!-drTn-.--Uther refJorted species include three-spine
stickle-back-s-rGasterosteus aculeatLAs} and sculpins. Attemrts to establish
popuiatioris of qrayTIriglThymallus arcticus) and tJastern bY'ook trout
(Salvelinus fG;:t-inaiis) in the upperarldlOwer lakes, respectively, were
not success-(iji~--fhe upper lake is not Known to contain any fish. Thet'e is
little sport fishi19 OG the Mahoney Lakes system probably due to the
relative remoteness ,)1' the site and the srnall populations of fish .
. Marjne fish and invertebrates are common in Georqe Inlet near the mouth of
Hahoney Creek. Pacific h2t~ring (Cl-'=!J~_.ea harengus) and various rockfish,
flatfish, and cod are present. Several clam, mussel, shrimp, and crab
species have also been refjorteci.
4.2.5 Water Quality
Water in the study area is of the calcium bicarbonate type. The pH in the
Mahoney Lakes system varies between 5 and 7. Alkalinitv in the upper lake
ha~ been found to be less than 5 mg/l. Low alkalinity is usually an
inoicat(Jr' ()T 11initecJ :)ioloqiul productivity (Cole, 1979). The dissolved
o;(ygen (O"c;-,:ntrai:i(Jil rneaslir'eci at the surface of -::ne upper laKe during the
surnillt~r was ~ lii9/1. r~1;2 velotica-: distribution of oxyqen iii the upp(~r lake
is probably quite !)nHortn because loltl levels of primary and secondary
~lr'oducr.in(i and ti~t: IOI'qp. VI}IUrle of water I,",ould inhiljit siqnificant
depletions of oxygen (due to decomposition) in the deeoer parts of the
US--12
lake. Uuring the sprihg, Upp~r Mahoney Creek was found to contain 12 mg/l
of dissolved oxygen. Mahoney Lake is known to have similarly hiqh levels
of dissolved oxygen.
. ..
Water temperatures in the· system fluctuate from just above O°C in the
winter to 16 to 12°C near the surfaces of the lakes in the summer. The
temperatures in Upper Mahoney arid Mahoney Creeks reflect the surface
temperatures of the 1 akes they drain. NoY'ma 1 patterns of temperature
stratification occ~r in the lakes. Further information on temperature
stratification can be found in a subsequent section dealing with project
impacts to fish.
Sedimentation and turbidity are not significant problems iq tile Mahoney
Lai<es system. lJespite hea.vy rainfall, steep slopes, dnd dynamic flow
regimes in the streams, erosion is minimal due to c6arse textured soils
with thick surface organic layer~, high infiltralion rates, and conditions
that favor rapid reve~etation~
In general, water q~ality 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 site, Ketchikan, is about 6 miles fr0m the
site. Approximately 10,000 to 15,000 people, including most of the
population of ~evillagigedo Island, live in the Ketchikan Borough,
depending on the season. Main industries are commercial fi~hing and for~st
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 infonnation can be obtained
by referring to the environmental conditions section and the main report.
The Mahoney Lakes system contains a spectaclllar lOO-foot waterfall between
the upper and lower lakes. Waterfalls are generally regarded as having
hiqh esthetic value and the Uppet' IYJahoney 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 th~ area.
4. c. 7 Cultural Kesources
Cultural resources on Revillagigedo Island haVe not been investigated in
detail. Tlingit Indians used the area near present day ~etchikan for fish
camps and a vi 11 age was located in the vi c i ni ty. George In 1 et was used fOI'
huntinq and fishing, but no permanent villages were located there.
Widespread settlement by native groups probably was precluded in many areas
by the steep, mountainous tenain of the island.
S.O 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
lower lake is a patchwork of forest and muskeg, and approximate acreages of
each habitat type affected by the project have not been determined. The
penstock route and powerhouse/tailrace site are primarily forested. The
road and transmission line from the camp to the powerhouse would impact
roughly equal proportions of forest and muskeg. Isolated pockets of raised
bog. elements of coastal forest, and exposed bedrock characterize the
proposed camp site, Hel iports near the penstock tunnel portal and damsite
would result in small losses of forest aDd alpine habitat (less than 1
acre); excavated material could be used in construction of project features
such as the dam. Approximately 45 acres of forest would be cleared for the
transmission line to Beaver Falls. An additional 75 acres adjacent to the
transmission line would be slightly affected through the selective removal
of trees that could potentially damage the line. The dam at the upper lakE
would result in inundation of about 19 acres of primarily alpine habitat.
5.1 Coastal Forest
Major impacts to old growth forest would result from clearing for roads,
structures, and the transmission line. The recommended plan would
permanently destroy or alter a relatively small area of forest adjacent to
I~ilhoney Lake. Greatest losses would occur along the tY"ansmission 1 ine
where vegetation would be maintained at an early successional stage.
Vegetation adjacent to the penstock tunnel portal would be Jestroyed by the
disposal of tailings.
The road alternative between Beaver Falls and the camp would permanently
destroy a substantial area of forest and subject adjacent land to erosion
because of steep slopes. In contrast, construction of the recommended dock
and seaplane float (to facilitate water and air access) would require
minimal clearing and should not cause significant erosion. Alternative
forms of access to the tunnel portal {e.g., construction of a road) would.
be considerably more damaging to the forest ecosystem than the recommended
use of helicopters.
Common plant species that would voluntarily revegetate in disturbed areas
include willows, fireweed (Epilobium angustifolium), horsetail (Equisetum
s~p.), and mosses. Later stages of succession would contain alders (Alnus
sPP-.), Sitka spruce, and shore pine, along with salmonberry (Rubus ---
Sj5ectabilis), blueberry, huckleberry, and numerous other shrubs and
perennial herbs. Similar changes in species composition occur in naturally
created openings. Vegetation along the transmission line corridor and
adjacent to the camp would be maintained in early successional stages,
precluding substantial growth of tree species. The most important effect
of these actions would be the permanent loss of a segment of the old growth
forest found throughout Southeast Alaska. Old growth forest is generally
considered to be unique because of the long replacement time of a stand.
IndividJal trees may reach 1,000 years of age. The aforementioned loss,
however, would be small when viewed from a regional standpoint.
While not considered part of the coastal forest, project impacts to the
alpine plant communities adjacent to the upper lake will be discussed in
this section. If the recommended 25-foot dam on the upper lake were
constructed, and the lake surface were raised to its maximum allowed by the
EIS-14
dam, about 19 acres of bedrock and alpine/subalpine vegetation would be
inundated. Since plant density, productivity, and diversity are relatively
low within these communities and the acreage to be flooded would be s~all,
this loss would not be highly signifi~ant .. Losses of alpine vegetation
would be more substantial if either the 50-or 75-footalterhative dams
were constructed. The impacts of other recommended or a lternat i ve features
on the forest ec6system would ~e minor.
5.2· Wetlands
Most of the land between the low~r lake and George Inlet, site ~f the
proposed camp, consists of isolated pockets of raised bog. A patchwork of
open bog, forested bog, and upland forest exists adjacent to the south side
of the lower lake wh~re the recommended access road and segment of the
transmission line are planned. The tamp and road would permanently destroy
several aCres of bog. Adjacent wetlands could be affected through the
disruption of surface and subs~rface flow patterns. Proper culverting of
rOdds in wetland areas would prevent significant adverse impacts to
hydrological functions. The affected bogs probably serve to filter runoff
water before it enters the lower lake. This function may be impaired by
the proposed road and camp construction, but not enough to significantly
affect lo~iJ water quality.
Because of the relatively small acreage involved, the above losses wo~ld
have a minimal effect on the biota of the larger wetland ecosystem.
Resid~nt wildlife could be affected through loss of habitat. The
ecological functions of adjacent bogs would not be significantly influenced
provided that changes in the hydrologic regime would be properly
mitigated. Normal drainage patterns should not be impaired. Other
recommended or alternative features would have little impact on wetlands.
The proposed project would have minimal impact on flood plain areas.
5.3 Wildlife
The construction of recommend~d features near the lower lake and the
transmission line to Beaver Falls would significantly alter or destroy an
estimated 63 acres of wildlife habitat. Selective removal of trees
adjacent to the transmission line right-of-way would have minimal impacts
to wildlife. Clearing of trees and understoryv;:>getation, particularly
along the transmission line route, would allow greater sunlight
penetration, stimulating the growth of herbaceous ground cover. These
changes would be initially favorable to black-tailed deer and a local
increase in the deer population could occur. However, unless clearings are
Inaintained at very early successional stages, this habitat would become
unusable to deer after 5-10 years (Wallmo, 1978).
Another consideration is that matu~e forests are important to deer during
the winter because during most years the canopy prevents significant
accumulations of snow, which allows deer to reach important ground forbs,
many of which remain green well into the winter. Lower quality browse
speCies are also more accessible under the forest canopy during the
winter. Excessive clearing could tesult in overcrowding within adjacent
forests during severe winters, which could lead to increased mortality.
EIS-1S
However, clearings created auring construction would be relatively small,
and much of the proposed road and camp would be constructed on muskeg that
is of little value to deer as winter habitat. Furthermore, research has
sho~m that deer n1.Jmbers in Southeastll,laska are below range carrying
capacity (Ulson, 1979). Overcrowding in adjacent forested areas is
therefore not expected to be a serious problem. S~asonal movements of deer
v!ould not be il~pai;'ed.
Inundation of alpine hdbitat after construction of the recommended dam on
the upper lak2 would have little o~ no impact on black-tailed deer. While
high numbers of deer are found foraging above timberline during summer
montns, th0se are8S adjacent to the upper lake that would be flooded are
ge~erally too steep for deer use, or are not easily accessible.
J~ca~se i) I :lC!( b:3ar's are not abundant near the t~ahoney '_akes, pr'oject
impacts to this spec~es would be slight. Blac~ bears, 1 i~c black-tailed
·:ker., \\fu;!d !Jen(:~Cit from an increased "edge effect" ofte,' ir,itial
clC;6.ri;!g. i=,.;Y' several years after project construction, cleared areas
would support the growth of succulent fnrbs such as skunk cabbage
tSt:~~chito.!:! drl]er_icanum), whicfl is preferred by bears in the spring. l"lost
t)2ars that nov; use nJf)itats adjacent to lower r~ahoney Lake, especially
muskegs, would probably move to more secluGed areas during project
const Y";j( t i ()n. Howeve y', i)ears ar'e often at traer.ed to garbage around project
sites, which increases the possibility of bear-human conflicts. In some
Cd',CS it ,:-, nece~:;sary to desty'oy nuisance bears. Careful storage and
uisposal af garbage should greatly reduce the number of huisance beats.
Wolf numbers would not be affected by the proposal. Since their main prey,
black-tailed deer, are not expected to decline, wolf populations should
I'emain scatic. f{ernoval of mature foY'est could adversely affect mar'ten
.through loss of den sites. Hm>lever, the number of marten that actually
OCClJr 1n thE': impAct area is.probably small, and adjacent habitat may be
able to absorb d~solaced individuals. Aquatic furbearers. such as mink and
riV2r otb~r, p(obably use riparian habitat along Mahoney Creei< to a gl'eater
extent due to tne moderate topography. Most aquatic furbearers along the
lower stream should not be greatly disturbed by the project. Project
impacts to beavers now using the lower lake. are difficult to predict.
During construction aquatic furbearers could be forced away from the lDwer
Take, particularly the south shore. However, many species may return 1fter
COrlstrl;ction has ended. In general, impacts to mammals would not be
significant, provided densities in adjacent habitats are below carrying
capacity and that these areas can absorb displaced animals. If adjacent
habitats contain theIr maximum supportable densities of a given species,
irnmigration ;jf additional memher's may cause stresses through competition
for limited \'2S0urees. This eouid result in a higher than normal t'ate of
fllol'tality unc~l the population again Y'f~i1thed an equilibrium with its
envi ronrnt':'r;t:.
The proposed project would have little or no direct effect on bald eagles.
However, })ot'~ntia! bi1ld eiqle nesting tlabitat may be diminished by the
removal of matuyp spr~ce along tne transmission line corridor. Use of
pCJwer po12s a.s unting perches can Y'esult in electrocution of eagles.
f)roper spacing minimum of 60 inches) and/or' insulation of 2rlp.rgized
US-16
hardware ca~ mlnlmlzethis problem (Olendorff et al., 1981). The U.S. Fish
and Wildlife Service has ·recommended that the transmission line be located
more than 1/8 mile from shdre to protect potential nesting areas and that
construction of the line follow design criteria outlined by Olendorff et
a1. (1981).
Blue grouse, especially hens with chicks, would benefit from rapid growth
of new ground cover along the edges of clearings. Grouse deniities near
the project site would be expected to increase and remain high if clearings
could be maintained at early suc~essional stages. Highest numbers of
ptarmigan are found in alpine habitats. Rock ptarmigan, and to a lesser
ext~nt willow ptarmigan, that use alpin~ areas adjacent to the upper lake
would be displaced after dam construction and subsequent water 1evel
i nCI'eases. The proposal is not expected to have any impact on wate,~fowl' ~
since suitable habitat is scarce and use is sporadic usually only for short
periods ..
Impacts to songbird species would be minimal. The loss of snags during
clearing could displace cavity neste~s. Clearing of old growth forest
would be. detrimental to highly specialized birds. Habitat losses, however,
would riot besignifica·ilt and serious reductions of bird populations are not
anticipated.
Inundation of an estimated 19 acres around the uppe>li'lke after
construction of the 25-foot dam would not have an appreciable effect on
wildl"ife. Wildlife use of alpine habitat adjacent to the upper lake is
very lo~. Steep cliffs (approaching vertical in some areas) and inadequate
food and cover appear to be the limiting factors.
Construction of additional roads, suggested a~ alternatives for access to
the general site (from Beaver Falls) and for reaching the penstock tunnel
portal, would result in greater losses of wildlife habitat. The
alternative dams (50 or 75 feet) would inundate larger areas of alpine
habitat than the recommended 25-foot dam. Although these losses would be
small on a regional scale, local impacts to wildlife could be significant.
If the tentatively recommended planr is ·modlfied to include any of these
alternatives, furth~r study could be required to fully evaluate potential
impacts.
Negat i ve impacts to wi 1 dl if e from other recommended or a lternat i ve featuY'es
should be minor. Hunting pressure around the Mahoney Lakes would not be
expected to increase since public access to the site would not be improved
above current levels.
The U.S. Fish and Wildlife Service assessed short and long term project
impacts to wildlife habitat (Habitat Evaluation Procedur~s). Standardized
models developed from literature about wildlife species in the project area
were used to derive an index of habitat suitability for selected wildlife
species. The Habitat Evaluation Procedures analyses and findings are
presented in the U.S. Fish and Wildlife Service Coordination Act report
(Appendix fIS-C). Project related habitat changes predicted by the Habitat
Evaluation Procedures analyses are consistent with conclusions drawn in
this report.
EIS-17
5.4 Fisheries
Project impacts to resident and andromous fish in the lower lake would be
related to the alteration of upwelling prbcesses and water temperature
change~. A dam at the outlet of Upper Mahoney Lake would essentially cut
off the flows to UlJper Mahoney Creek. The )'ecornmended Py'oposa 1 calls for a
lake tap 225 feet below the surf~ce of the upper lake. Water from the
upper lake would ;law through a penstock to a powerhouse and would
ultimately discharge into the lower lake. Alterdti~n of normal flows to
the lake could upset upwelling proce~ses along the western shore of the
lake. Normal ternperatureregimes of Mahoney Lake may also he influenced by
the discharge of 4°C water drawn from the upper lake.
The quantity and placement of water discharged from the powerhouse are
important when considerin~ project effects on sockeyes. Upwelling
proceSSF~:; allwg the western shore of the 1 ake COrl'E:spond prirnari ly tb flows
fy'()1TI Uppel' r"i(\hon~y Ci'eek. Currents created by upwel '1 ng are necessary to
insure proner development of sockeye eggs. Flows in Upper Mahoney Creek
would be rf.:>duced after constrl)ct1on of the dam at the outlet of Upper
Mahoney Lake; a small flow could be maintained by runoff from the adjacent
'I.'atersh,~d. Impacts to sockeyes cou:d iar~:~ f)'om mi nor t'J significant
depending on the design and location of Ule tailrace.
To mitigate potentidl disruption of upwelling processes in the lower lake,
taiir<Jce \"'3te)'S C;ilOUld be discharged as far above the lake as possible.
Water should also be spread D1er a large area to simulate preproject
braided conditions. This would insure maximum intra-gravel flows to points
of upwelling along t~e western shore of the lower lake.
In the upper lake, water at the depth of the proposed lake tap is at or
near 4°C year-round. Water reaches its maximum density at 4°C; therefore,
the deeper parts of lakes are normally at this temperature. During the
surnmer, as ~::urf ace:.'~tt~t'S warm correspond i ng to i ncreas i ng air temperatures,
denslty barriers become more pronounced and temperature stratification
reaches its maximum. Warmer, less dense waters remain at the surface while
colder, denser water's are found near the lake bottom. An intermediate zone
(thermocline) lies betwee~ these strata where the temperature changes
sharply_ During the winter~ an inverse stratification pattern develops,
which results in colder waters (O_3°C) near the surface overlying warmer
4DC water of maximum density.
Temperature stratification patterns in the lower lake are similar to those
in the upper lake. As colder water would be discharged into the lower lake
during summer project operation, it would flow to the deeper areas and mix
with water of similar temperature and density. Depending on the volumes
released, the influence of this cOlder water could affect the temperature
of ovey'lyina str'ata. The thermocline could b"2 pushed toward the surface,
low~ring the overall temperature of the lake.
The volumes of water normally entering and leaving the lower lake are shown
in Table EI5-3. In the current project proposal, the volume of water
.. released tI1 1'OU'jh the penstock 'liiould approxirnatethe average yeaY'ly
discharge of 40 cfs now flowing from Upper Mahoney Lake. This amount is
expected to remain constant throughout the year. DUYing r.:ritical summer
months when te~peratures in the lower lake are at their maximum, the volume
of water discharged from thepower~ouse would be significantly less than
contributions to the lower lake from .other sources. Therefore, temperature
declines in the ldwer lake as a whole duting summer months would be minimal
and populations of resident fish would not b~ affected.
S i gnif icallt temperature changes in the 1 ower 1 ake duri ng winter months are
also not anticipated. COritributions to the lower'lake from other sources
during certai n wi nter Inonths may be s 1 i ght ly 1 ess than vo 1 umes di scharged
by the project; However, except for a thin layer near the surface where
temperatu~es range from 0 'to 3°C, winter temperatures in the lower lake are
almost uniformly 4°C; Therefore, winter patterns of temperature
stratification should serve to minimize the influence of 4°C water
(discharged from the powerhouse) on the lower lake as a whole.
Whi Ie t:le temperature regime of the lower lake would not change
significantly, local temperature changes in the lake near the mouth of
Upper i'~ahoney Creek would occur. Anadromous sockeye salmon that currently
spawn in this are~ would be adversely affected by an influx of 4°C water.
The possible impicts of colder water on sockeyes during September through
Novemher (peak spawning and initial egg development) are summarized below:
1. Spawning behavior could be discouraged (Sheridan, 1962; James, 1956).
2. The proportion of eggs deposited may be reduced (Andrew and Geen, 1950).
3. Increased egg mortality could occur (Combs, 1965; Bailey and Evans,
1971) •
4. Improper embryonic development, if initial temperatures are less than
67C, could result (J. Bailey, National Marine Fisheries Services, personal
communication) .
Inferences about temperature related impacts on sock eyes were, in some
cases, derived from pink salmon .research.
A number of options are available to mitigate the potential adverse effects
of 4°C water temperatures on sockeye salmon during critical spawning and
initial egg inCUbation periods (September-November):
I. Warmer water could be pumped from the surface of the lower lake into
the tailrace to raise 4°C water above the threshold temperature of 6°C.
2. !~ portion of the tailrace could be diverted a~vay frorn the Upper Mahoney
Creek delta while allowing remaining tailrace waters to reach spawing
areas. This assumes that natural ruhoff f~om the Upper Mdhoney Creek baSin
would rnoderate the temperature of the reduced tailrace volume before it
wuuld reach points of upwelling. However, water temperatures at points of
upwelling in the lower lake would be less predictable due to high
variability in the rate and temperature of watershed runoff. Inconsistent
runoff patterns could also affect rates of upwelling (since tailrace
volum(~s would be reduced). While this option may reduce the negative
impacts of allowing the full tailrace volume to reach spawning beds
(without temperature control), lonq term sockeye productivity would
probably diminish.
E1S-19
==~=--==--==-..=:-=~----:::-:-:::-::--=~:::-~-==--=:--:-.::-==:=:--~-=-=~:--==_~=:c_:..~~=··::':==_--::'~-=.-:::::-:..~~~-~~-~~-::-::: ~.=::-~-=-~....,..,.;::-..::::";:.==~==~-:=.-~~-::.===-~=
Table EIS-3
Selected Water Discharge Data for' the ~1ahoney Lakes System
Annual
,Jan. Feb. ~1ar • Apr. ~lay Jun.
Volume leav'ins the
Jul . ~lJg. Ser~_, Oct. Nov. Dec. i\verage_
10\\ler hke in
r'Ll. ho ney Cree!< (c fs ) 56 58 {f li 67 D4 152 124 104 104 160 l?l 89 102
Volume entering
10\\le( 1 ake hom
Upper' Mahoney Lake
watershed (cfs) 24 20 n 20 48 58 £15 37 64 79 41 23 40
Contribution to
lower lake from
rrt . sources other than
en Upper t~ahoney Lake
I
N watershed (cfs) 32 38 28 {[7 86 94 79 67 40 81 81l 61l 62
0
Source: U.S. Geological Survey Water-Data Reports.
3. Construction of a multi-level intake structure in the upper lake
pl~rrnit the extraction of water .from strata of selected temperatures.
option would be considerably more expensive than 1 or 2 and benefits
not significantly different.
would
This
are
4. A nonstructural measure would be to remove eggs from adult sockeyes
each year and transport them to a hatchery. After hatching and initial
developm~nt, fry could be transported back to the lower lake to rear for
1-2 years. In addition to high annual costs, this option would not resolve
the fundamental problem.
Uption lapp~a~s to be the most practicable and· effective method of
Illaintaining a productive and self-sustaining population of ?rliidrr)l11ou5
sockeyes in the Mahoney Lakes system. By late November, it would be
unnecessal'y to pump "'later from the lower lake into the tailrace. Lake
temperatures would be approaching 4°C (and would, therefore, not influence
tailrace temperatures) and eggs would be tolerant of colder temperatures by
thi s time.
While the tentatively recommended mitigation would insure normal spawning
behavior anu prevent initial egy mortality and embryonic def0rmities,
incubation periods could still be altered. If warmer water from the 10wer
lake is mixed with tai.lrace waters, the resulting water temperatures at
points of upwelling would be in the range of 6 to goC during September and
Uctober. Slightly lower temperatures would probably result in November
because of declines in the temperature of lake water. Normal temperatures
(without project) at points of upwelling during September are about 100e.
Temperatures fall gradually to about SoC by late November. Project
discharges would, therefore, result in a slower rate of egg development
between September and early November, which cOuld lead to delayed hatching
and fry emergence.
Conversely, during later stages of egg development and subsequent growth of
fry within gravel (approximately December through Ma~), '~ater discharqed by
the project to lake gravels would be slightly warmer than the temperature
of upwelling water without the project. Under normai conditions (without
project), the temperature of upwelling water along the western lake shore
drops below 4°C by mid-December. A minimum temperature of about 2°e occurs
in February. Temperatures gradually increase throughout spring months and
wat'~r usually reaches 4°C by early May.' Because \'later discharged by the
project would be 4°C, development of eggs and fry could be accelerated
sl ilJ~ltly during winter and ear.ly spring, which could result in the
emergence of fry into the lake before adequate food supplies (plankton) are
present.
In light of the probable project related water temperature changes that
wuuld occur from S~ptember through May, accelerated development of eggs
during the spring could be offset by a slower rate of development during
the fall. Tne net result may be fry emergence during a normal time frame
when food supplies are adequate.
tIS-21
To accurately predict fry emergence after project construction, additional
data are needed. Normal water temperatures at sockeye spawning sites must
be measured continuously from time of egg deposition to fry emergence. An
index of the temperature/time relationship required for normal incubation
and fry :1':vPi'Jpment can then be derived. A second index value can be
derived by :.'foj.::cting the new water temperature regime at the spawning
sites t)etween egg (leposition and fry emergence after' pr'ojectconstruction.
Comparlson of thest: values would show whether fry emergence during project
operation i'Jouldoccur earlier or later than under normal circumstances. A
signifi£ant deviation from the time of normal emergence could be mitigated
by manipulating tailrace water temperatures using a previously recommended
mitiqative strategy. As data become available, the above indices will be
developed to ref~ne this assessment of project related impacts on sockeyes.
Asa measure to increase sockeye production in the 10wer la~e (after losses
are flllly (ompensated), a proposal to construct an artificial spawning
channel in the tailrace was described briefly under the alternatives
section. Effectiveness of this proposal would depend on the degree of
control over temperature and flow regimes in the tailrace. Substrate
conditions wOL'ld need to reflect the requirements of sockeyes. To properly
address thlS type of enhancement, the carrying capacity of the lower lake
and population dy~amics of sockeyes using the system would require
additional research, which is beyond thE scope of the present feasibility
study. Cur'rent efforts should focus on cost effective mitigation of
project related losses. If the current proposal is implemented, a
monitoring program should be initiated to: 1) confirm predicted project
impacts on sockeye:;, 2) assess effectiveness of rnHigation, and 3)
evaluate unforeseen project impacts on fish in Mahoney Lake, if necessary.
A small number of Dolly Varden have been reported using pools near the base
of the Upper Mahoney Creek falls. This habitat would be reduced upon
implementation of the project. The use of alluvial gravels from Upper
f~ahoney Ueek may rA~ necessary for consttuction of the service road.
Excavation would be restricted to those areas above the powerhouse site.
Also, because downstream sedimentation could be severe, work in the
streambed would not be permitt~d during periods of sockeye spawning and egg
incubation in the lower lake. Flows and water temperatures at the outlet
of the lower lake would not be significantly altered by the proposal.
Therefore, impacts to fish and invertebrates in Mahoney Creek and Geotge
Inlet would be negligible. Effects on fish from other recommended or
alternative features would be minimal.
5.5 Wc:1:er QU-3,lity
Water qua1-ity in the r~ahoney Lakes system would not be significantly
degradeo by the proposed project. The pH, alkalinity, and oxygen levels
are not exnected to change. Gas supersaturation in tailrace waters, a
problem a~sociated with some hydropower projects, would not occur because:
1) the penstock intake .. lOuld not be exposed to the atmosphere at any time,
2) gas concentrations near the level of the proposed intake are
substantially below 100 percent saturation, 3) turbulence in tailrace
waters would not exceed levels now occurring naturally i~ Upper Mahoney
Creek, and 4) temperature increases of tailrace waters as they flow into
E15-22
the lower lake would not be great enough for supersaturation to occur.
Project impacts to water .tempe~ature regi~es would also not be significant
except in a highly localizedareaalonq the west shore of the lower lake.
An analysis of project related water tem~erature changes 0as presented in'
the pre~ious section dealing with impacts to fish.
The disposal of an estimated 37,000 cyof excavated material (derived from
the penstock tunnel and discharqe road) on slopes adjacent to the tunnel
portal may increaSe sedimentation and turbidity levels in the lower lake.
l'luch 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 :110110 exposed banks
and increase turbidity levels. This is not expected to be a significant
prODlem in Upper Mahoney Lake. Much of the area that would be expos€:d is
bedrock or large material that would .not be sus~ertible 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. '8arge dotking 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
fal Is to the site would be subject to severe erosion due to the steep
slopes. Wat~r quality problems associated with this alternative would be
1II{)}'e significant thanirnpacts associated with tile recommended form of site
acces s.
5.6 Socioeconomic 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 econom-ic growth in the community is not an objective. The
purpose of the proposed project isto supplement the projected energy
demand for KetChikan. However, slight social and ecomonlC growth in
Ketchikan may be associated with the construction phases of the proposal
dll~ to an inflUX of workers and their families.
Implementation of the proposal would result in the loss of the waterfall on
Upper f'~ahoney Creek. [-he relative esthet.ic value of the fal is is difficult
to IneaSU1~e since the number of visits by people to within viewing range 'is
unknown. Most viewing of the falls is probab.ly incid~ntal to other
activities such as sport fishing. Therefore, the significance of this loss
is not readily apparent. In general, the proposed project WOJld diminish
the esthetic value for those who perceive an undisturbed natural
environment as appealing or desirable.
G.? 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 nistorical or archaeological sites (Steele, 1981).
EIS-23
5.8 No fIction
If the proposed project is not constructed~ the City of Ketchikan may be
forced to rely on jiesel generators for electricity. This would subject
consurners to extremely high energy costs associated with escalating diesel
fuel prices, and would perpetuate environmental problems associated with
diesel generation (see 5ection 2.1). The forests, wetlands. wildlife,
fish. water qualit" and esthetics assotiated with the Mahoney Lakes would
not change if the hydropower proposal is abandoned. This assumes that
other unforseen land uses do not alter the natural environment in the
Mahoney Lakes area.
6.0 ~UBLIC INVOLV~MENT
Un 17r~arch 1975, a formal public meeting was held in Ketchikan to explain
th p Corps' mission regarding the study of hydropower pot~ntial in Southeast
Alaska. The Ketchikan City Council, in a resolution passed on 17 April
i 91~. r'~qll;~sted that Ketchikan be the. Corps' number one priority for the
study of hydropower in Southeast Alaska.
~etween iYJ5 and 1980, the Corps, in accordance with scoping requirernents,
contacted various State and Federal agencies for their assistance in
identifying environmental concerns associated with the proposed Mahoney
lakes project. Coordination with the U.S. Fish and Wildlife Service and
the Alaska J~partmenl of ~atural ~esources was initiated pursuant to the
Fish and Wildlife Coordination Act and the Preservation of Historical
Archaeological Data Act of 1974, respectively. Correspondence received
during initial scoping activities is provided in Appendix EIS-A. A
Coordination Act l"epurt was prepared by the U.S. Fish and Wildlife Service
and submit ted in J\pril 1979.
In 1981 and 1982, field investigations revealed new information about the
fish resources in tile Mahoney l.akes system. It subsequently became clear
that the recommendations and Habitat Eval~ation Procedures analyses
pr~sen[ed irl the 1979 COQrdination Act report were inadequate. Beginning
in early 1982, the seoping process was reinitiated to solicit updated
cornrn~-!nts on tile cur,'ent. proposa 1. Correspondence recei ved -j n response to
1982 seoping dctivities is provided in Appendix EIS-B. A revised
CoorJinatlon Act report was submitted to the Corps in November 1982 and is
contained in Appendix EIS-C. I{ecommendations presented in the Coordination
/~r:t report and ,:qaska Uistrict responses are summar-jzed in Table [lS-4.
6.1 ~eQuired Coordination
The U.S. Forest Service, in a letter dated 31 March 1982, requested that
tney be designated as a cooperating agency for the Mahoney Lakes study.
kecognir;nq the Forest Service's management responsibilities for lands
a~-f<?cted hy the propos:'il, the Foreq: Service was riesiqnated as a
cooperating agency by letter dated 4 May 1982. This action will insure
proper coordini'ltion b':'twel~,; the Corps and Forest Service throughout the
planning process. Coordination with various Federal and State agencies
having jurisdiction by law or having special expertise, as well as other
interested or affected publics, will continue throughout later stages of
pi all n i r~ 9 .
E1S-24
Table EIS-4
U.S. Fish and Wildlife Service Recommendations and Alaska District Responses
Recommendations
1. All human garbage should be
carefully stored and disposedof~
2. The transmission line should
be located more than 1/8 mile from shore.
3. The transmission line should be
designed and constructed to avoid
potential raptor mortality c~used
by electrocution and/or entanglement.
4. Water from the powerhouse tailrace
should be returned to the streambed
as far above the lower lake as
pract i cab 1 e. _ The use of pumps to
accomplish this measure should be
investifjated.
5. Pump(s) should be installed in the
lower lake to supply a sufficient quantity
of water to maintain preproject
thermal conditions.
6. A monitoring program should be established
concurrent with project ~evelopment 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 necessary. Alternatives that
could be considered would include an
artificial spawning channel. The COE, FWS,
ADF&G, and NWFS would be the primary
participants in the design and implementa-
tion of this study.
===-~===========~===
7.0 STATEMENT RECIPIENTS
Responses
1. Concur, as this action
would be necessary to
minimize bear-human
conflicts. See"EIS text.
2. Concu\~,)S this action
would be necessary to protect
potential bald eagle nesting
habitat. See EIS text.
3. Concur. Standard
mitigative designs
are available. See EIS text.
4. Concur. Additional study of
existing stream dynamics is
necessary. Limited number of
alternative powerhouse sites
affects final location of tail-
race discharges. See EIS text.
5. Concur, as this action
would be necessary to maintain
sockeye productivity in the
Mahoney Lakes system. See
EIS text.
6. Concur. This is essentia-I
with most large scale
developments and would provide
an invaluable data base for
similar future projects.
A complete listing of draft EIS recipients is included in Appendix I of the
ma in report.
EIS-25
8.0 LIST OF PREPARERS
The following people wer~ primarily responsible for preparing this
draft EIS:
Name Discipline
Mr. Richard A .. Weide Wi1~life Biologist
Ms. Ju1 ia Steele Archaeology
Mr. Harlan Legare Hydraulic Engineering
Exp-eri ence Role in Preparing EIS
6 months, bio. tech., EIS coordinator and
principal preparer. U.S. Fish and Wildlife
Service. 1 year, bio~
tech., Corps of Engineers.
1-1/2 years wildlife
biologist, Corps of
Engineers.
Prepared cultural 1 year, grad~ate field
work in Alaska ~nd
New York. 1 year,
archaeologist, Dept. of
Interior. 3 years,
archaeologist, Corps of
Engineers.
. resources sections
of EIS.
3 years, engineering
consultant, E.A. Hickok
and Assoc. 2 years
hydraulic engineer,
Bureau of Indian Affairs.
2 years, project manager,
Corps of Engineers.
EIS-26
Plan formulation
and development of
alternatives.
g.u II~lJEX
Subj ect
Affected Environment
Environmental 5etting
~ignif~cant Resou~ce~
Coastal Forest
Cultural Kesources
Fisheries
Socioeconomic and Esthetic Resources
water Quality
w(~tl ands
Wildlife
Alt",rnatives
No Action Alternative
Plans Considered in Uetail
Plans Eliminated from Further 5tudy
Comparative ImDacts of Alternatives
Alternative Features
No I~ction
Tentatively Recommended Plan
tnvironmental tffects
Coastal Forest
Cultural Resources
f i s~leries
I~u I~ction
Socioeconomic and Esthetic Resources
Water Quality
Wetlands
\~i Idl ife
List of Preparers
Need for and Ubjectives of Action
Planning Objectives
Publ ic Concerns
Study Authority
Public Involvement
Required Coordination
Statement Recipients
Summary
EIS-27
Paragraph
4.0
4. 1
4.2
4.2. 1
4.2.7
4.2.4
4.2.6
4.2.5
4.2,2
4.2.3
2.0
2.2
2.3
. 2. 1
3.0
3.2
3.3
3. 1
5.0
5. -I
5.7
5.4
5.8
5.6
5.5
5.2
5.3
8.0
1.0
1.3
1.2
1.1
6.0
6. 1
7.0
E15-7
EI5-7
E15-8
E15-8
. E15-14
EI 5-11
E15-13
EI5-13
EIS-9
EI5-10
E15-1
EI5-3
EI5-3
EI5-1
E1S-5
EI5-6
E15-6
EI5-5
E IS-14
E15-14
EI5-24
EI5-18
EI5-24
E I5-2J
EI5-22
EI5-15
E15-15
E15-26
EIS-1
EI5-1
E15-1
E15-1
EI5-24
E 15-24
E15-26
EI5-i i
10.0 LiTERATURE CITEU
Andrew, F.J. and G.H.Green~ 1960. Sockeye and pink salmon production in
~elation to proposed dams in the Fraserkiver system. Int. Pac. Salmon
Fish. Comm. l3ulL XI.
Bailey, J. 1982. Personal communication with Mr. Jack E. Bailey of the
National Marine Fisheries Service. Auke Bay, Alaska.
Bailey, J.E. and O.k. Evans. 1971. The low-temperature threshold for pink
s~lmon eggs in relation to apropos~d hydroelectric installation.
Fish. Bull. 69 (3): 587-93. . .
~ull,E.L. 1978. Specialized habitat requirements of birds: Snag .
management, old growth, a~d.rip~rian habitat~ p. 74-82 in Proceedings
of the workshop on nong~mebirdhabitat management in the coniferous
forests of the westen United States .. USDA Gen. Tech. Rep. PNW-64.
Pacific Northwest Forest and kange Experiment Station Portland, Oregon.
Cole, G •. A.1979. Textbook of limnology. The C.V. IYJosby Company. St.
Louis, Missouri.
Combs, B.D. 1965. Effect of temperature on the development of salmon eggs.
Prog. Fish-CDlt. 27: 134-37.
Harris, A.S. and W.A. Farr. 1974. The forest ecosystem of Southeast
Alaska. No.7. Forest ecology and timber management. USDA, Forest
Service General Tech. Rep. PNW-25. Pacific Northwest Forest and Range
Experiment Station, Portland, Oregon.
James, G.A. 1956. The physical effect of logging on salmon streams of
southeast Alaska. Alaska Forest Reserach Center, Station Paper No.5,
USDA, Juneau, Alaska.
Martin, J.W. (ed.). 1959. Stream
i<.etchikan management district
reports -fisheries, No. 305.
Washington, D.C.
catalog of t~e eastern section of .
of southeast Alaska. Special scientific
U.S. Fish and Wildlife Service,
Martinson, C. and D. Kuklok. ·Uridated.. Atlas of the Ketchikan region.
KetChikan Gateway ~orough Planning Department, Ketchikan, Alaska.
Meehan, W.R. 1974. The forest ecosystem of Southeast Alaska. No.4.
~i ldlife habitats~ USDA, Forest Service General Technical Report
PNW-J6. Pacific Northwest Forest and Range Experiment Station,
Portland, Oregon.
EIS-28
Olendorff, R.R., A.D. Miller, and R.N. Lehman. 1981. Suggested practices for
raptor protection on power lin~s -The state of the art in 1981. Raptor
Research Rep. No.4. RaptorResearch Found., Int. Dept. of Veterinary
Biology, Univ. of Minn., St. Paul, Minnesota.
Olson, S.T. 1979. lhelife and times of the black-tailed deer in southeast
Alds~a. p.160~168 in O.C. Wallmo and J.W. Schoen (eds.). Sitka
blaCK-tailed 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.
submarine DC electric power
D Report, Vol. 1. Prepared
Administration.
Reconnaissance design and ccst estimate of
transmission system in southeast Alaska. Task
for U.S. Dept. of Energy, Alaska Po~er
Wanmo, O.C. 1978. f"1ule and black-tailed deer. p.3l-41 in J.L. Schmidt and
D.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
APPENDIX EIS-A
CORRESPONDENCE FROM INITIAL SCOPING ACTIVITIES (1975-80)
__ o--,.J
UNITED STATES
DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE
1011 E. TUDOR nD.
INHLPLYHUHiTO: S~ ANCHORAGE, ALASK/\ 99503
(9071 276·3800
H"/l
Colonel Lee R. Nunn
District Engineer
AlnskaDistrict, Corps of Engineers
P.O. Box 7002
Anchorage, Alaska 99510
Dear Colonel Nunn:
30 MAY 1980
This responds to your Hay 19, 1980, request for a list of threatened or
endangered species which may occur in the following project areas:
Location
Village of Mekoryuk on Nunivak Island
Village of Sca~~on Bay
Cordov.1 Interim
Chichagof Island
Mahoney Lakes near Ketchikan
Activity.
Two breakwaters and revetment
Small hydroelectric project
Southcentral Railbelt hydro-
electric project
Small hydropower project at
l'enakee Springs
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 (HiS) 113S 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 wi th the F\.JS 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 Harine Fisheries Service (NMFS). ~'hereas some of your
proposed projects are in or adjacent to marine waters, you may wish to
contact NHFS 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 answ.er your. questions.
a;;; !l~~G
Area Director
EI S-A-2
HI·) 11 Lli
DIVISION OF PA RKS
May 20, 1980
Re: 1130-2-1
Harlan E. Moors
Chief, Engineering Division
Alaska District, Corps of· Engineers
P. O. Box 7002
Anchorage, Alaska 99510
Subject: Mahoney Lake Hydroelec.tric Project
Dear Mr. Moors:
(
Chip Dennet~ein, Direct6r
619 Warehouse Or., Suite 210
Anchorage, Alaska 99501
274-/4676
l,~e have reviewed the subj ect proposal and would like to offer the follmdng
conIDlents:
STATE HISTORIC PRESERVATION OFFICER
The proposed.hydroelectricproject 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 ar28. Therefore, under provisions of 36 CFR800, a
preconstruct ion cultural resources survey is recommended.
Sincerely,
~.
~fff'P"Dcnnerlein I ~ Director
~
William S.
-DEI»l\J:''l'~IENT OF NATUltAL ImSOUltCES
February 2, 1973
Re: 1130-2-1
J. K. Soper, Chief
Cngineering Division
DIVISION OF PARKS
Alaska District, Corps of Engineers
. P.O. Box 7002
. AI,chorage, Alaska 99510
Dear Mr. Soper:
JAY S. HAMMOND, GOVERNOR
619 Warehouse Dr., Suite 210
Anchorage, Alaska 99501
This letter is in response to your request of January 29th for our views on
Lhe MClhoncy Lakes and Lake Grace projects and their involvement with
archaeological or historic properties (your reference NPAEN-PL-EN). Our
comments oenerally parallel those of Dr. Gerald Clark in his letter to your
oftJcl:; which you had enclosed. We feel that the Mahoney Lakes area of the
camp imd Clccess road and the sal twater access area should be archaeologically
sU!'vcy(~d prior to Clny finalizution of plans. The power line as Dr. Clark
notc'd uppears to be a low potential area; however, we would like to see the
documentation of the possible or probuble impacts on the lnines indicated in
your' routing sheet. In the Lake Grace area the power line as Dr. Clark
arpin mentioned is a low probability area; however, the access area and camp
dfca 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,
!d~~
Wiiliam S. llanable
Stute Historic Preservation Officer
Ol{: py
cc: Dr. Gerald Clark, Regional Archaeologist
U. S.D. A. forest Service
P.O. Hox 1628
junciiu, Alaska 99802
ElS-A-4
I
FEDERAL ENERGY REGULATORY COMMISSION
REGIONAL OFFICE
555 Battery Street, Room 415
San Francisco, California 94111
Colonel George R. Robertson
District Engineer .
Alaska District~ Corps of Engineers
P. O. Box 7002
Anchorage, Alaska 99510
Dear Colonel Robertson:
March 1, 1978
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
'''etlakatla. The Ketchikan Public Utility (KPU) 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 oil 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
1,500 kW unit \'Iith a heat rate of 10,500 Btu/kWh, capital cost of $370
per kilowatt, service life of 35 years, and fuel oil cost of 44¢/gal10n.
REA financing at 5.0% interest rate was used for MPLw
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,
,-~ ~ ~. ~.... .. -'"-...... ,.-t.~t.A.~
EU9arJ.b 1 ett
Acting Regional Engineer
Attachment
cc: North Pacific Div.
Corps of Engineers
Table 1
Value of Hydroelectric Power
at
Ketchikan Market
Municipal Financing .(@ 8.0% interest)
Capacity
Energy
49.50 $/kW-yr.
32.60 mills/kWh
Federal Firiancing (@ 6-5/8% interest)
Capacity
Energy
. 41.38 $/kW-yr.
32.60 mills/kWh
Table 2
Value of Hydroelectric Power
at
Combined Ketchikan and Metlakatla Markets
Composite Financing (Mtinicipal @ 8.0% and REA @ 5% interest)
Capacity 1/
Energy 2/-
47.61 $/kW-yr.
33.82 mills/kWh
Federal Financing (@6-5/8% interest)
Capacity 1/
Energy 2/-
42.93 $/kW-yr.
33.82 mills/kWh
y 75% KPU plant capacity value + 25% MPL plant capacity
value .. y 80% KPU pLant energy vaLue + 20% MPL plant energy value.
EIS-A-6
I
l)g -R(C~-111··~·0
T'K. -E~
United States Department of the Interior
FISH AND WILDLIfE SERVICE
ALASKA AREA OFFICE
8130 STREET
ANCHORAGE, ALASKA 9950-1
Colonel George R. Robertson
District Engineer
Alaska Dfstrict, Corps of Engineers
P. O. Box 7002
Anchorage, Alaska 99510
Attention: Environmental Section
Dear Colonel Robertson:
Re: NPAEN-PR-R
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
UlelTI are:
(1) As was originally proposed, the tailrace waters to be channeled
directly into the lower lake.
(i) 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
Save Energy and You Serve America!
CTC: 11_7
2.
depend on the speclTlc 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 draina~e would be curtailed. This alternative appears
to be the least acceptable.
Alternative #2 should be an acceptable choite provided the magnitude of
mlnlmum flow 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 spawningchann~l 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 utiliz~ the natural stream spawning
areas in addition to the 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, thet'efore, appears to be the most desirable--it.s greatest
drawback being one of esthetics.
Physical Profile -fisheries oriented
Upper Mahoney Lake Lower Mahoney Lake
2 mi 2 5.7 mi 2 (includes
upper lake)
Drainage Slze
Lake surface area 57.5 ac. 160 ac ..
(115.2 ac. by Retherford)
Lake depth
Lake volume
Surface flow
Spawning gravel
Water temperature
Gic10gical Profile ------------
Pldnkton
A~uatic vegetation
Invertebrates
Fish
Native
Introduced
!J2f)('r Mahoney Lake
265 ft. (80.8 m.)
5000 acre-feet (E~t.)
'1\' Inlet -15 cfs 8/4/77
'G' Inlet -40 cfs 8/4/77
Ins i gn ifi cant
WI77 Air ~~
Sur'face -9. oOe
Thormocline °
~/5 m -7.2/6.6 e
Some diatoms & others
1977
Secchi disc -30 m
1977
No data available
1977 -abundant
(including chironomids,
stoneflys, diptera,
caddis, mayflies and
leeches)
None observed
Gr"yl i ng -1966
(without apparent success)
EIS-A-9
3.
Lower Mahoney Lake
220 ft, (67.1 m.)
20,400 acre-feet
Outlet records show a
range from 2 cfs ~o 171 cfs
and an average of approx.
40 cfs .
. 540 m2 from base of fa~ls
to lower lake. 1060 m-
total.
Surface -4.7 oe
6 m .. 4.0oC
4.00 C to bottom
No data available -
however, appears more
productive than upper
lake.
Sparse -ADF&G 1952/70
Present -ADF&G 1952/70
"Insects & lar'vae, snails
and pea clams"
A11 salmon except kings;
kokanee, rainbow, stee1-
head, dolly varden. cut-
throat, cottids and
stickleback.
Eastern brook 1931-32
(without apparent success)
An introduction of kokanee
was also apparently made.
1977 Observations
Upper Mahoney Lake
.Nofish observed
*Nate:Historically, many pearle
subsistence fished for sockeye salmon ..
The system has since been closed to
all subsistence fishing.
Other vertebrates Waterbirds, bear,
deer and furbearers.
4.
Lower Mahoney Lake
Abundant kokanee, and dolly
v'arden i nl ake. Sockeye* ,
pink, and chum salmon observed
in spawning condition in streams.
Dolly varden fry observed in all
areas.
Eagles, ducks and other water-
birds, grouse, bear, deer and
furbearers.
We a~preciate the opportunity to provide planning aid comments and data.
Please keep us advised as to project status and let us know if we can be
of further assistance.
. Since.rel Y yours, ,(. _ rM_.~ /JJ·;.~0JVb AS~i,t'ilJ~~~/J {)L .
EIS-A-10
j.
L.
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
P.O. Box 1628, Juneau, Alaska 99802
Mr. George R. Robertson
District Engineer
Corrs of Enoineers
P. O. Box 7002
Anchorage, Alaska 99510
Dedr Mr. Robertson:
2360
e··~~·' ~
"
~_='-"""' .. :C--
The following is in reference t6 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 presen~ly
known In this vicinity; however, the vicinity of the dock and work
Cili:I/J 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 10\'/ potential.
-.
b. Swan l.ake: No historic/archeological sites are presently known
HI the near-'vlcirlity of the lake, powerhouse, and transillission line to
tlw point of crossing Carroll Inlet. Potential for historic/archeolog'ical
liiCtterials in these a\"eas is judged to be low. The transmission lir',e
from Niqelius Pt. -Shelter Cove -Ward Cove will be in the vicinity of
a ~etroglyph reported in Shelter Cove and a large historic site identified
by S~alaska Corporation in Leask Cove. The potential for archeological
sites along the inland portions of the transmission line is low.
c, ~_~h<?ney 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 considet'ed high. The first
half of the transmissiol, route to Beaver has a medium to low petential;
the second half has a low potential ..
Dr, Pcbert Ackerman, Department of Anthropology, vrdshington State
University, Pullman, Washington, has conducted a partial archeoiogical
sdrvey of the Swan Lake Hydroelectric Project for R. W. Beck and
AssociatAs. When this survey is completed, we will be in a position
t(l ijrovide firmer dat.a concerning histor1c/archeological !:~aterials for
that portion of the study area.
62.00· 11 (: /69)
EIS..,A-ll
•
2
I hope the above information is of help. Please do not hesitate. to
call if your require further assistance.
Si ncere ly ~
(I ~J" ,~.Q(9 ~J -(lJ,~. f ~
GERALD H. CLARk
Regional Archeologist
EIS-A-12
United Slales Department of the Interior
FISH AND WILDLIFE SERVICE
ALASKA AREA OFFICE
8130 STREET
ANCHORAGE, ALASKA 99501
Colonel George R. Robertson
District Engineer
Alaska District, Corps of Engineers
p. O. Box 7002
Anchora~e, Alaska 99510
Dear Colonel Robertson:
Re: NPAEN-PR-R
.IU~J 1977
This responds to Mr. D. G. Hendrickson's letter of April 27, lSn,
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
vrill modify our comments should the results of that investigation
so dictate. Due to the lack of sufficient quantitative data on the
saln~n 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,
rarticularly pink, chum, coho, and sockeye salmon; and Dully Varden,
cutttn'oat, rainbow, and steelhead trout which use the inlet streams
to the lower lake as a spawning ground. Grayling wer~ stocked in
the upper lake 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
illcluriiny both resident species and those which depend on the estuaries
at some stage in their 1 ife history. Among the estuat'ine fish resources
are all species of Pacific salmon, the searun varieties of trout,
Save Energy and You Serve America!
EIS-A-13
Pacific herring, several species of rockfish, several species of
flatFish, and cod. Shellfish resburces includ~ several species
of clams and mussels, several species of shrimp, and Dungeness
. and other crab species. .. .
\.J{ldlHe resources that are closely associated with this estuarine
;oystem include waterfowl, seabirds, shorebirds, and seals. Bald
eagles, deer, black bear, grouse, beaver and other furbearers use
substantial portions of the ecosystem~
. .
2 ..
Based on the data available at this time,the maintenance of spawning
and rearing habitat for salmon andtroutjn the stream flowing between
Upper l·lahoney Lake and Lo~!er 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. /\ny overflow from the
upper lake should be allowed to follow the existing natural route.
A minimum \vater flow in the natural stream channel during the spawning
and i ncubati on peri ods of July throughr~arch must be mai ntai ned.
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
"wy require further restrictive comments on the proposed project.
We appfeciate the opportunity to provide conments at this early stage
of project planning and to alert you to our primary concerns relative
to this project.
s'ncerelY:;SdJ I'~~
ector ~
EIS-A-14
APPENDIX EIS-B
CORRESPONDENCE FROM FINAL SCOPING ACTIVITIES (1982)
DEPARTMENr OF NlUIJRAL RESOURCES
April 27, 1982
File #: 1130-2-1
Harl an E. Moore
Chief, Eng-ineering Division
DIVISION OF PARKS
Corps of Engineers, Alaska District
P.O. Box 7002·
Anchorage) AK 99510
Dea r ~'r. Moore:
JAY S. HAMMOND, GOVERNOR
·6'9 WAREHOUSE DR_, SUITE 210
ANCHORAGE, ALASKA 9950'
PHONE: 214-4616
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.
SLK/ jdg
MEMORANDUM State of
1 L----'-, A I ask a fL .~ (3 (\J
TO.
FROM:
Dave Haas
State-Federal Assistance Coordinator·
Division of Policy Development
DATE:
FILE NO:
and Planning
Juneau TELEPHONE NO:
..DC
Don Cornelius
Area Habitat Biologist
Department of Fish and Game
Ketchi kan '{..v-
SUBJECT:
April 14, 1982
AK 820325-02
225-5195
I~ahoney Lake
HydropO'.'ler
Feasibility Study
The Department of Fish and Game has reviewed information supplied by the
U.S. Arn~ Corps6f Engjneer~ tegardtng Mahoney Lakes Hydropower Feasibi-
lity Studies. W-e havethefollowing comments regarding this proposed
project:
1. The potential effects of this project on red salmon which spawn
above lower Mahoney Lake must be investigated. As proposed, the
pens tock ta i1 race route woul d vi rtua lly dry up the probable spav/n-
ing beds of this salmon population by removing water fro:il 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 and 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 vJith "gas bubble" disease. Project design should
include methods to remove gases including nitrogen and oxygen \'Jhich
may supersaturate the water discharged from the tailrace.
EIS-B-2
~k. Davt:! Haas - 2 -
April 14,1982
4. The need for this facility in the. Ketchikan area shouldbeevaluated.
The S~'/an Lake Hydroelectric Project will soon be on line and Grace
Lake located in the Swan Lake vicinity has been mentioned as a
possible hydroelectr'ic power source which may be constructed after
S\'Jan Lake. Do other alternatives exist?
Thank you for the opportunity to revi~w this proposed project. We look
forward to v.JOrking ·with the Corps dur·ing completion 'of this £IS ..
cc: R. Reed -ADF&G -Ju~eau
H. Moore -COE -Anchorage
C. Osborne ~ USFWS -Ketchikan
u. s. E NV I RO N MEN TAL PRO TEe T ION AGE N C Y
REPl Y TO
AnN OF; MIS 443
I APR iS~
Colonel Lee R. Nunn
District Engineer
REGION X
1200 SIXTH AVENUE
SEATTlE, WASHINGTON 98101
Alaska District, Corps of Engineers
P. O. 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 vater quality conditions at all depths of Upper 11ahoney 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 unveget~ted 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 temperatm'es, 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 qual ity 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. r1itigation measuY'es
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 inlpacts from the construction camp, temporary
generating facility, and obtaining and process construction material
such as sand, gravel and rock.
2
We appreciate the opportunity to participate in this scoping process.
Dick Thiel, my Environmental Evaluation Branch Chief, may be contacted
. for mor€. infonnation .. He can ·be reached at (206) 442-1728 or (FTS)
399-1728. .
LGary . O'Neal, Director /pd'L Envi ronmenta 1 Services Di vi s i on
cc: Ron Kreizenbeck, AOO, ·Juneau
EIS-B-5·
UNITED STA.TES DEPARTMENT OF AGRICULTURE
~fr. Harlan E. Moore
Tongass°1faYiornii ICrorest
Federal Building
Ketchikan, Alaska 99901
907 -225-3101
U. S. Army Engineer District, Alaska
ATTN: Chief, Environmental Section
P.O.-Box 7002
Anchorage, Alaska 99510
L
Dear Mr. Moore:
1950
March 31, 1982
Thank you for your f1arch 22 1 etter concerni ng 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 parti ci pati ngi n 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 appropri ately coordi nated duri ng the preparati on 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.
Si ncerely,
~?7Z-?~ C? df~;'
~MES A. CALVIN
Acting Forest Supervisor
620D-ll (1/59)
E1S-B-6
/
March 31, 1982
Colonel Lee R. Nunn
District Engineer
UNITED STATES DEPARTMENT OF COMMERCE
National Oceanic and AtmospherlO:: Administration·
National Marine Fisheries SerJice
P.O. Box 1668
Juneau, Alaska 998D2
Alaska District, Corps of Engineers
P.O. Box 7002
Anchorage, Alaska 99510
Dear Co·10nel Nunn:
This letter is in response to your Section 7 request for information regarding
threatened or endangered species unde~ the National Marine Fisheries Service's
responsibility that may be present in the vicinity of the t·\ahoney Lake system
near Ketchikan, Alaska
Endangered Species
National Marine Fisheries Service bears responsibility for eight species of
endangered vlhales which occur in Alaskan waters; they are:
Blue
Sei
Fin
Black Right
Bo\"ihead
Sperm
Gray
. Humpback
Balaenoptera musculus
. Balaenoptera borealis
Balaenoptera ~lus
Balaena glacialis
Balaena mysticetus
Physeter ~acrocephalus
Eschrichtius robustus
Megaptera novaeangliae
Humpback whales are probably the only endangered whale that !i',ay occur near the
project area. About 1,000 humpback whales (of a total \'JOrld population of 6,000)
inhabit the North Pacific. During the sumner 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 SUP.1rner and autumn. It;s
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 (Ilupea harengus), and cape1;n (~iallotus vinOst~).
(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
apparent1y 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.
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 northwar~
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 Novemher and December.
Gray whales do not feed while migrating along the California coast, but possible
surface-feeding be~avior has been reported during sprin~ migration at Cape
St. Elias (Cunningham and Stanford 1979). On the summer grounds gray whales
feed primarily on benthic gammarideanamphipods.
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.
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 nnd its associated stream system
provides habitat for several fish species, i.e., pink salmon, sockeye salmon,
chum salmon, coho salmon, steel head trout, sea-run cutthroat trout and Dolly
Varden char. Juvenile sockeye salmon rear in the lake while juvenile coho
salmon) steel head 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. rIe wi 11 offer our comments and recornri1endati ons on the
proposed project when we review the draft environmental impact statement.
We hope this information will be useful in the planning process.
Sincerely,
EIS-B-8
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 R~s. Inst. 31:69-84
EIS-B-9
I·
United States Department of the Interior
INREPLY REFER TO:
FISH AND WILDLIFE SERVICE
1011 E. TUDOR RD ..
SE ANCHORAGE, ALASKA 99503
(907) 276-3800
Colonel Lee R. Nunn
District Engineer
Attention: Mr. William D. Lloyd
Alaska District, Corps of Engineers
P. O. Box 7002
Anchorage, Alaska 99510
Dear Colonel Nunn:
Re: NPAEN-PL-EN
1 6 MAR 1982
This responds to your ~arch 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 jn 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.
Qcere y,
~-v7_ m
. -~ Regional Director
cc: ES
EIS-B-l0
United States Department of the Interior
IN REPl Y REFE:R TO:
Colon~l Lee R. Nunn
District Engineer
FISH AND WILDLIFE SER VICE
P. O. Box 1287
Juneaui Alaska 99802
December 21, 1981
Alaska District, Corps of Engineers
P. O. Box 7002
Anchorage, Alaska 99510 Re: NPAEN-PR-R
Attention: Environmental Section
Dear Colonel Nunn:
This planning aid letter is to re-evaluate some of our recO!::mendations
and to transmit new information relative to the Mahoney Lakes hydropm"er
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 "Thich 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 Hahoney Lake (storage reservoir) and Lower "!-fahoney Lake.
The suitable spawning gravel contained in this stream co~prised 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
ef fect expected from the proj ect. Ultimately in the CA report \<"'e
recommended serious consideration of measures, including an art.ificial
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 Lm"er
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 draf ting 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.
2.
At the outset, REP 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 REP evolved it
became clear that REP can be used to accomplish anyone or more of the
follO\ving:
1. Quantify lands necessary for mitigation (as before)
2. Evaluate alternatives
3. Predict recovery
Also, it has become evident that the procedure can range from an expensive
large scale elaborate procedure (when the project merits it) toa rather
informal minimum expense project for a specialized purpose; and, there are
many proj ects \o,'hich are not sui table for the application of REP.
The suitability of the Mahoney Lakes project for the application of REP
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 REP 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 knmm to Spa\offi 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 bet\veen 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 flm"
patterns. These observations and the lack of observed sT"l.?'min:?, unstrea:rl
from the lake serve to stron3l~ sug~est that tbe adult sockeye are not
sf'avmin,. unstream from the lake. Since it is extreTI'el~T il'lprobable that
the youn~ fis~ can ni~rate upstream to' the lake, we strongly suspect that
the adult fish are spmming 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 \vill be submitting a modified CA report with re-eva1uated
recommendations.
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 8.5 9 5.8 17 4.8 40 4.1
2 7.7 10 5.6 18 IL6 50 4.0
3 7.4 11 5.4 19 4.5
4 7.2 12 5.2 20 4.5
5 6.6 13 5.0 21 4.5
6 6.4 IIJ IJ.9 30 4.2
7 6.2 15 4.9 31 4.2
Depth measured in meters; temperature in degrees centigrade.
'vater 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 o
May 17, 1981 o
August 29, 1981 11.5
Water teIll.I'...-~rature in lower lake on the L1ce of the delta (the area suspected
to be used for spawning).
December 9, 1981
4.
On December 9, 1981, a recording thermograph was installed on th~ faceo!
the delta in approximLltely 15 feet of water and will be recovered five
months later. The resultant information should help define the temperature
regime in this area.
·Incubation time varies with water temperature from around 140 days at
about 4°C to aroun~ 50 day~ at ~bout lSoC f6r 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 ~ary from positive to negative depending on a multitude
of factors including the degree of change. We feel it is beyond the scope
I. of nur resources to study this sufficiently to predict it and that the
relative ~otential imoact on the fishery resource in this project does not
\\larr2nt it.
~e hope the information in this letter proves useful.
Sincerely yours,
;;?I/~ t. ~
Field Supervisor
EIS-B-14
FEDERAL ENERGY REGULA TORY COMMISSION
333 MARKET STREET, 6th FLOOR
SAN FRANCISCO, CA. 94105
June 2, 1982
Mr. Harlan E. Moore
Chief, Engineering Division
Alaska District, Corps of Engineers·
P. O.Box 7002 .
Anchorag:, Alaska 99510
Dear Mr. Moore:
As requested in your letter of February 10, 1982 (NPAEN-PL-R) ,and in reference
to my letter of February 23, 1982, we have completed estimates of hydroelectric
power values for your studies of the Upper Mahoney Lake project in the Ketchikan
area.
The at-market values of dependable hydroelectric power delivered in the Ketchikan
area are based on the estimated costs of power from an alternative source de-
scribed as follows:
A diesel engine-driven generating unit of 6,896 kW capacity, with a
heat rate of 9,380 Btu/kWh, operating at a 58% plant factor; capital
cost of $435 per kilowatt, service life of 35 years, and fuel and
lubricating cost at $1.087 and $3.53 per gallon, respectively.
The following va1ues are based on January 1982 price levels for federalfinanc-
ing at 7-7/8% interest rate. Energy value considering real fuel price escalation
assuming a project on line date of 1992 is also provided.
Federal
Financing
7-7/8%
At Market Value of
Dependable Hydroelectric Power
Price Level -January 1982
$/kW
56.34
. Wi thout Fuel
Cost Escalation
mills/kWh
84.69
With Fuel
Cost Escalation·
mi lls/kWh
252.93
These values include both hydro-thermal energy and capacity adjustments. The
capacity value adjustments reflect only the equivalent availability of the diesel
unit. The hydrologic availability factor sholJld be applied to arrive at the
total adjusted capacity value. Real fuel cost escalation is based on DOE pro-
jected energy prices as published in the;r n l98l Annual Report to Congress,
EI S-B-15
'. ---
.Volume 3~ Supplement 2," of February 1982 •. The breakdown of costs you have re-
. quested are shown in the attached table.
Attachment
Copy to North Pacific Division
Corps of Engineers
Sincer~ly , J;'jQ .. "..,--,y'-N~. e:;[ ~~< ~
( or) W. F . Kopfl er, II
Regional Engineer
EIS-B-16
UPPER MAHONEY LAKE PR(kIECT
Ketchikan. Alaska
At-Market Hydroelectric Power Values
J.anuary1982 Price Level
Investment Cost $435/kW
Annual Fixed Costs
Interest and amortization
Fuel inventory·
Lubricating oil
Fixed Operating
Total Annual Fixed Costs
Adjusted At Market Capacity Value
Energy Cost
Fuel
O&M
. Tota 1 Energy Cost
Adjusted At Market Energy Value
EI5-:-B-17
$/kW
36.84
6.40
0.06
9.42
52.72
. 56.34
mi 1 1 s/kWh
77 .89
5.29
83.18
84.69
APPENDIX EIS-C
U.S. FISH AND WILDLIFE SERVICE
COORDINATION ACT REPORT (1982)
United States Department of the Interior
FISH\ND WILDLIFE SERVICE
IN REPL Y REFER TO: 1011 E. TUDOR RD.
ANCHORAGE, ALASKA 99503
(907) 276-3800
Colonel Neil E. Saling
District Engineer, Alaska District
Corps of Engineers
P.O. 80x 7002
Anchorage, Alaska 99510
Dear Colone1 Saliny:
Re: Coordination Act Report
Mahoney Lakes Small Hydropower
Ttlis 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 wildlif~ resources, as
outlined in the attached CA Report, be incorporated into the development
plall. The re~ort has been coordinated with Alaska Department of Fish and
Game and National flarine Fisheries Service, however, their comments were not
received in time for incorporation. We will forward these comments upon
r2ce i pte
vIe appreciate the opportunity to comment and advise on matters regarding
fish and wildlife resources associated with the proposed hydropower develop-
lilent plan.
Sincerely,
~/~dSc<~/-L ~~ ~k/< /'
"I..t;'l'r-• ,,~~ <l'~! Regiona 1 Director
Enc10sure as stated
cc: ADF&G, Juneau, Ketchikan
USFS, Sitka
FWS, ROES, Juneau, Ketchikan
FWS. Federal Projects, WDC
W1FS, Juneau
t~AHONEY LAKES PROPOSED St1ALLHYDROPOWER DEVELOP~lENT
COORDINATION ACT REPORT.
Prepared By
C~arles 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
TABLE OF CONTENTS
1.
II.
I I 1.
IV.
Introduction ..•
Ar~a Description. ...
Project Description.
tlethods -General. '.' . . .•.
A. Terrestrial Study -tlethods ..
. . . . . .
.'. . . .
Cover Types . . . •
Species Selection.
Field Sampling.
Resu lts . . .
'. . . .
B. Aquatic Study ..
Cover Typ ie s. .
Species Selection
Field Sa~pling ..•••
Results ....
Discussion and RecoITIhlendations .
Literature Cited ....•••.
Glossary
. . .
Page
1
2
3
3
5
5
6
G
.lD
17
• 17
17
.18
19
• 21
26
TABLES
Table I. Species list
Table I1~' Acreag'es and conditions of ter:restrial cover types on
'the target years '
Table III. HSI and HU for each, species in each targ~t year
Table IV. AAHUand HU change during the, 50-year 1 ife of the
project and during the 275-year baseline-to~recovery
life of the project
Table V. Fish census in Mahoney Creek, Falls Creek, and South
Creek 7/16-10/31/81 '
FIGURES
Figure 1. Location of the Mahoney Lake System on Revilla
Island
Figure 2.1 Symbolistic layout of project
Figure 3.1 Map of study area, durect impact area, and cover
types at Mahoney Lake
Figure 4. Map of Falls Creek -4/81
Fig~re 5. Map of Falls Creek ~ 8/81
APPENDICES
Appendix A. Determination of photo scale
Appendix B. Models used
1 , There is some distortion of these maps due to elevation differences
at the study site. See Appendix A for explanation.
11ahoney Lake Coordination Report -1-
I. Introduction
Maroney Lakes is one of three Ketchikan area potential hydroelectric
power projects. A preliminary feasibility study was done (Retherford et
a1., 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).li .In that report it was suggested that the
COE acquire lands for rehabitation to compensate for losses in wildlife
habitat. In May of 1930, 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.
1/ 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 terrestriil methodology used in an aquatic
habitat.
Mahoney Lake Coordination Report ~2-
An interagency team intluding 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 to outline the Mahoney Lakes study.
At this time the specie£ 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.
II. Area Description
The r1ahoney Lakes system consi sts of connected lakes located in the
southern portion of Revillagigedo Isl~nd (Fig. l)~ 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
slightly over 1 mile before entering the lower lake. Discharge from the
lower lake travels almost three-tenths mile before entering George Inlet
at a point 16 miles byw8ter from Ketchik~n.
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.
T
Manoney LaKe Looralnatlon KepOrt -j-
III. 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 lake. 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 lake. 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 Man~als
(Anon., 1980-1981). However, for the casua 1 reader, a brief sumillary of
the HEP process foilows.
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 a 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 le¥eJs 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 f1ahoney Lakes
system plus the transmission line area (Fig. 2). The transmission line
area extends from the ~ahoney 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 followin9
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 N55l5-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.
Mahoney Lake Coordination Report -6-
A. Terrestrial Study
Covertyp€s
Three covertypes were chosen for evaluation 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 Ens 102 (Anon. 1980-1981). A list of
species in the area was made from the tlahoney 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 b~sed 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 entaiJed 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 1~ 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 (USFt:S, 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 \Jas 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 ranaomly 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 i~ another randomly selected
direction. There were six transects established in the mJskeg.
Mahoney Lake Coordination Report -8-
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)(lOO), 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 ale (1980). Plant
species were identified according to Viereck and Little (1972).
The number of samples necessary was determined for each suitability
index (5.1.) 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 5.1. 's because
. more than one plant species was included in a single 5.1.; 2) two
different sampling methodS (transect and quadrat) were often used because
both shrub and ground cover species coula be included in some S.l.'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 ale
(1980), more samples were needed for statistical significance. The
number of samples determined necessary ranged from 5 to 97 for the
different S.l.'s. Because of the questionable validity of applying the
sample size test to S.l. '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 5.1. for each covertype was
T
11ahoney Lake Coordination Report -9-
used to select sa~ple 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.l.: percent cover of
macrophytes. Since the percent cover which indicated a certain index was
within broad limits (see tlink model, App. B), an occula. estimate of this
variable was made at the proposed dock site.
All S.l.ls, Life Requisite values (LR~s). H~b;tat Suitability Indices
(HSI1s), Habitat Units (HU's), and Average Annual Habitat Units (AAHU's)
were calculated according to ESI1 102 (USFWS, 1980-81) and the individual
models.
Five taryet years were chosen for predicting habitat suitability:
TYO TV 1, TY 50, TYllO, and TY275. Target years 0, l~ 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 conditions 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 frJm Harris and Farris (1974)
account of secondary succession. Acreages of each covertype after
project implementation were estimated using information from the r1ahoney
Lakes liydropower 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 ~one because, tor some species, major
Mahoney Lake Coordination Report -10-
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. Resu lts
The total study area includes 5,221 acres and the direct impact area
. includes 2,090 acres (table II; 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 proj€ct: 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 vlith 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 disturbed 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.
Mahoney Lake Coordination Report -11-
Tne 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 sholJld
take longer to revegetate than the transmission line area because the
extent of disturbance, such as establishment of the road hed, 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 strllctures will be long lasting and, therefore, the recovery
rate of the conif~rous forest in this area is iJnknown.
The dock will cover approximately 0.2 acre of saltwater aquatic: or
intertidal, area. This area should rapidly revegetatc and return to
baseline conditions within a few years of termination of US1Jage.
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
The following information includes species accounts of model
implementation and hydropower project impacts as predicted by HEP.
Black Bear
-12-
The black bear model used was designed by Lana Shea (1981) (App. 8).
Two coverty~es, 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 Hithout 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 TYllO, canopy closure in the developed areas, including the
transmission line and roads, decreases the spring to fall range values
(LR l and LR 2 ) 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 Hil's as compared with over 4,000
HU's lust during the project's lifetime.
Sitka Black-Tailed Deer
The ~ode1 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
V1, the percent cover of shrubs within x yards, was eliminated.
Consequently, the aggregation function for the life requisite
spring/summer/fall range, LR 1, 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 transm~ssion
line, and muskeg were evaluated for the project life, target years TY1
and TY50. After project's termination, regrowth coniferous fore~t 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 51 as specified in V7 of the
model (App. B). In the coniferous forest, these SI 's were then increased
by 0.1 or C.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, LR1
was greater than LR2 (winter range). Winter fdoge was considered
~lahoney Lake Coord; nat i on Report ... 14-
limiting, so the HSI was equal to LR 2• In the muskeg LRl was less
than LR 2 . However, since LRl is probably not limiting in the
ecosyste~, LR2 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 fo~est (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 (LR 1) would improve in quality, but winter
range (LR 2 ) 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
LRl and LR2 range would be sub-baseline due to 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 E~
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, V2 , was modified to include Alaska yellow cedar and western red
cedar, two prominent species in southeastern coastal forests. The
Mahoney Lake Coordination Report -15-
suitability of the distance of an area from shore, V6 , was also
modified, based on personal co~nunication with Jack Hodges, FW5, and
Robard~ 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 H51 value was the lowest LR
value; and the H5I 's for the covertypes were aggregated using an area
weighted mean.
The H5I '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 H51 0.8 and 296 acres at H51 0.08 to give 588 acres which
have an average H51 of 0.44. The difference between the 2 H5I 's is
solely the result of distance from shoreline, V6: area 0-1/8 mile from
shore having a 51 of 1.0, and area from 1/8 to 1/4 mile from shore having
a 51 of 0.1. Therefore, in reality, there are 292 acres of fairly g00d
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
TYllO 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 -16-
Blue Grouse
The model used to evaluate habitat suitability for blue 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 LR 3 , winter food; and muskeg was evaluated for LR 2, late
spring/summer/fall food (rearing). After project implementation,
coniferous forest that had been converted to roadside and slash was
evaluated for LRl and LR 2 , not LR 3 • 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 TYIOO, 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) over the 275-year recovery life of the project (Table IV).
The model for mink in Konkel et ale (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 t1ahoney Lakes
area. The lowest LR value was chosen as the HSI value for saltwater
aquatic~ and because only one rovertype was evaluated, no further
Mahoney Lake Coordination Report -17-
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 w6uld 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 ti~e period if the project were implemented (Table
I II & IV).
B. Aquatic Study
Cover types
The f1ahoney Lakes study area inc ludes two aquat ic covertypes,
lacustrine and riverine. There are three streams: Falls Creek, South
Creek, and f1ahoney Creek; and four 1 akes: Upper and Lm'{er flahoney Lakes,
and two lakes which drain into Upper Mahoney Lake (Figs. 2 & 3).
Species Selection
A number of salmonid species are reported from the naho~ey 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 lake 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 selected to represent a species which would use
Falls Creek for rearing, as fry were trapped there in 1977 by the ADF&G.
Removing Falls Creek would result in the lo~s 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 ~f Falls Creek from lower
Mahoney Lake to the first permanent blockage to upstream migratibnof
salmon. The study was accomplished in two field trips: 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, aepth, and bank conditions
were then evaluated for each section. In 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 me~t the requirements
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.
Resu lts --
It is approximately 1,500 feet from Lower Mahoney lake to the first
permanent blockage of salmon migrati9n 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 uppet 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 f1m/ing and covered 0.26 acre. This dry bed
situation was observed on some of the subsequent stream census dates,
8/12, 0/18 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 O. 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 ill small schools just offshore and in the mouth of
Mahoney Lake Coordination Report -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 9/10/8 1 • 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 a long the west shore of Lm'ler t·1ahoney Lake. Th is \'>Jas the first
confirmaticn 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 /,lahoney Creek on the same
date. Streams flowing into and out of Lower tlahoney 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
Falls 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.
V. Discussion and Recommendations
The direct impacts of a Mahoney Lakes power project would be
primarily the loss and alteration of some wildlife habitat.
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/b.ear 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 TYl and TY50
(as compared with the baseline HSI); and during TYllO 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 Coordinatio~ Report -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
rap tors is potential mortality due to electrocution and/or entanglement.
We recommend that the power lines be designed and constructed in such a
manner as to avoid this potential problem area. Design criteria should
be patterned after those illustrated and discussed in Olendorff et al.
(1981).
A dam at the outlet of Upper r-lahoney Lake would eHminate flo\,/s in
Falls Creek. This, in turn, would disrupt upwelling processes along the
west shore of the lower lake. 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 6~~ early winter. However, by mid-
winter the 4°C discharges would be s7ightly warmer than normal, whereby
development of eggs may be acceleratea. If fry emerge lnt1 the lower
lake earlier 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 floa:ing intake structure in the upper lake;
2) pumping water from the lower lake into the tailrace; and 3) creatio'l
of an artificial spawning channel.
We understand there are some severe technical constraints associated
with item 1 above. We would, ther0fore, recommend that pump(s) be
installed in the lower lake to noderate 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 r1arch). 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 whe~eby adverse and or beneficial
impacts to sockeye salmon would be eVdluated and a pump operation
schedule would be devised. Study participants would include
representatives of the CaE, FWS, National Marine Fisheries Service (NMFS)
and ADF&G.
At an agreed upon time the study participants would evaluate the
success of the ~itigation measure and relommend necessary changes.
Mahoney Lake Coordination Report -24-
Recommendations
To provide miti0ation for project associated adverse impacts, the FWS
recommends the following:
1. All human garbage should be carefully stored and disposed of.
2. The transmissibn line location sho~ldbe located more than 1/8
mile from shore.
3. The transmission line be designed and constructed to avoid
potential raptor mortality caused by electrocution and/or entan-
glement. See Olendorff et al., 1981.
4. 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.
5. Pump(s) be installed in the lower lake, capable of supplying a
sufficient quantity of water to maintain preproject thermal
conditions.
6. 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 N~lFS
would be the primary participants in the design and
implementation of thiS study.
Mahoney Lake Coordination Report
Literature Cited
U.S. Fish and Wildlife Service, 1981. Habitat Evaluation Procedures
Workbook. HEP Group,
-26-
Western Energy & Land Use Team, U.S. Fish & Wildlife Service. Drake
Creekslde Building, 2625 Redwing Road, Fort Collins, CO 80526
U.S. Fish and Wildlife Service, 1980-81. Ecological Services Manual
Habitat Evaluation
Procedures. ES~1 100-104. Division of Ecological Services, Fish and
Wildlife Service, Dept. of the Interior.
Anon., 1979. tlahoney Lakes Hydropower Project. United States Dept. of
the Interior, U.S. Fish & Wildlife Service, Anchorage, Alaska. 21 PPM
Anon., 1978. Mahoney Lakes Hydropower Project.
Anon., 1974-80. Climatological Data. Vol. 60-66. U.S. Dept. of
Com~erce, 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
Alaska 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, Port1and, OR.
Konkel, G. W., et al. Terrestrial Habitat Evaluation Criteria Handbook -
Alaska. Div. of Ecological Services, U.S. Fish & Wildlife Service,
Anchorage, Alaska.
OJendorf, 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 V~terinary 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.
Agriculture Handbook No. 410.
Agriculture, Washington, D.C.
1972. Alaska trees and shrubs.
Forest Service, U.S. Department of
Glossary of HEP terms
Aggregation function -the methematical function which ~mbines 51's
to an LR value, LR values to a cover type H51, or ~oyer type H5I
to a single HSI
Average Annual Habitat Units (AAHU) -the number of ~ lost or gai~ed 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 dete~mining
impacts of development to habitat; may be used to compare alternatives,
predict impact, and quantify m~tigation necessary
Habitat ~itability Index (H5I) -an index between 0 and 1 which represents
the quality of a habitat for a given speciesf the HSI may be far 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
HU = HSI x acres
Life Requisite (LR) -a need of a species such as food, cover, or reproduction
Life Requisite value (LR i ) -an index between 0 and 1. which represents the
capacity of a given habitat to support a life requisite of a species;
one or more 51 determines a LRi
Suitability Index (51) -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
T able I
Species List (from Mahoney Lakes Report, March, 1979)
Mammals
black bear
Si tka black-tailed deer
\lIolf
beaver
river otter
mink
martin
shre\lls
voles
red squirrel
\lIeasel
Birds
northern bald eagles
blue grouse
ptarmigan
ru ff ed grou se
spruce grouse
plus a variety of marine
winter residents, migrating
ducks, shorebirds, and
seabirds
Fish
pink salmon
chum salmon
coho salmon
sockeye salmon
steelhead trout
sea-run cutthroat trout
Dolly Varden char
Table II. Acreages and condition of terrestrial cover types on the target years
Cover type Acres In Acres in Direct Impact Area
. Study· Area TYO TYl TY50 TYllO TY275
Alpine, snowfields .1644 668 1
Coniferous forest
steep,subalpine 867 401
Coniferous forest
old growth 2078 1651 ·1507 1507· 1507 1643
t ransmi ssion line 119 119
road 7 7
plant 8 8
camp 11 11
regrowth 137
condition unknown i 8 8
Muskeg
unal tered 272 100 96 96 96 96
camp 4 4
condition unl4nown 4 4
Saltwater aquatic
unal tered 21 21 20.8 20.8 I
dock 0.2 0.2\ 21 I 21
I
Slide 58 24 1 I
I I
Riparian 25 3 1 I
I Lacustrine 256 222
Total 5221 3090
1 not evaluated
--33
Table Ill. HSI and HU 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
HU 1453 1309 1425 1381 1444
Sitka black-
tailed deer HSI 0.62 0.61 0.61· 0.57 0.62
HU 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
HU 840 1729 1729 818 835
l"1ink 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 Tya ~ TY50 Total II HU IS Tya -TY275 Total If HU' s
Black bear -84 4188 -53 14343
Sitka black-tailed deer -36 1782 -51 14097
Northern bald eagle -62 3118 -25 7003
Blue grouse +915 45736 +253 69631
Mink -1 50 ...... ..:., 275
Table V. Fish Census in Mahoney Creek, 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
7/22/81 0
7/28/81 0
8/8/81 100-B~Ok soc~eye
8/12/81 0 0 0
8/18/81 ? -llJater too milky 0 0 but fish seen
jumping
8/24/81 2f p~g~eye
8/29/81 f9 ~~~eye 0 0
9/10/81 ~§ ~gBkeye 0 0
1 p~n~s
9/24/81 0 0
10/14/81 0 0
10/31/81 ·0 0
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Project Map
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Steep ,s~lbalpine
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Coni ferous faresl
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[);.rpct impact 81:'1
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Key: water boundary
- ---gravel boun'dary
...
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12~61 size of rock In section bf stream (inches)
p-22 pool -depth (inches)
d-5 depth bf stream -inches
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r-lO % of section suitable for rearing
Scale: I" = 60'
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Key -App.A -Fig. 1
1 Coniferous forest
2 Muskeg
3 Slide
4 Steep, subalpine forest
5 Alpine, snail/fields
6 Streamside
7 Intertidal (saltwater aquatic)
8 Lacustrine
photo boundaries
.-.-. boundary of direct impact area
APPENDIX A
HYDROLOGY
APPENDIX A
HYDROLOGY
Table of contents
GENERAL
Basin Description
Streamflows
CLIMATE
Temperature
Precipitation
Snow
W"ind
Storms
Ice and Frost
Snowslides
STREAMFLOW RECORDS
Extension of Streamflow Record
Sedimentation and Water Quality
Evapotranspiration
FLOOD CHARACTERISTICS
Snowme It Floods
Rain Floods
Past Floods
Probable Maximum Flood
Area Capac ity
Low Flow Frequency
Tables
A-l
A-2
A-3
A-4
Monthly Streamflow Distribution as Percent of Annual
Stream Gaging Stations
A-5
A-h
A-7
A-8
A-9
A-ll
Mahoney Creek Correlation with Fish Creek
Average Monthly Precipitation and Runoff,
Mahoney Lakes Basin
Percentage of Total Monthly Runoff Attributable
to Upper and Lower Basins
Evaporatio~ Losses
Maximum Instantaneous Recorded Discharges
Annual Maximum Instantaneous Recorded Discharges
at Mahoney Creek
Mahoney Creek Flood Frequency
Rainfall Distribution of the Probable Maximum Storm
Page
A-l
A-l
A-4
A-4
A-4
A-5
A-8
A-10
A-10
A-10
A-ll
A-ll
A-ll
A-17
A-17
A-19
A-19
A-19
A-19
A-;! 1
A-25
A-25
A-4
A-12
A-15
A-16
A-17
A-19
A-20
A-2l
A-22
A-24
A-l
A-2
A-J
A-4
A-5
A-6
A-7
A-8
A-9
1\-10 .
A-11
A-12
A-13
A-14
1\-15
A-16
A-17
Figures
Ketctli kan 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 l~vel) 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
Correlatiori analysis ~-Mahoney Creek vs. Fish Creek
Monthly Distribution of annual flow from Upper
Mahoney and Mahoney Lakes
Peak discharge frequency at Mahoney Creek
Sumnary hydrograph of the Mahoney Lake~ basin
Probable maximum flood hydrograph for the Upper
f"1ahoney basin
Inflow and outflow hydrographs for the standard
. project flood
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
Low flow frequency curve for the Mahoney Lakes basin
A-i i
A-2
A-3
A-6
A-7
A-9
A-13
A-14
A-18
A-22
A-23
A-26
A-27
A-28
A-29
A-30
A-31
A-3?
Basin Description
P,PF)E@~X f~
~iY DROI_OCW
Ule proj\~ct area lies within the reg·jon of maY'll':lle influence of
soutileas~ern Alaska and is in the path of most cyclonic storms that cross
tile Gulf of j\laska. Consequently, the iJ.\~ea rec(~ives little sunshine,
genF:~rall'y moderate temperatures, anG i,bundant j.H'ecipitation.The rugged
terrain exerts a fundillnental influence JPon luca1 temperatures and the
distribution of precipitation, creating consirlerable variations in both
weather elements.vithin i~eli1tively shoy·t distances. The area is subject to
frpquent winter storms of varied precipit~tion intensi!irs, ~ith rare
occurrences of hai 1 and thunaerstorms. Th~ ~'1(ihlir,,~y Lakes proj!Cct ,::rt:d is
shown on the locati()n lfIap of Figure /\-1.
The Mahoney Lakes drainage b3sin is locatea ~pp~oximately 6 air miles
northeast of Ketchikan and 5 mil(~,s nOdJI of tlr~ r3eaver Falls powerhouse on
George Inlet. The Upper Mahoney bJsin va-i~s in elevation from 1.950 to
3,350 feet abo,e mf.~an sea :evel (['I15L) \"ith un aJI,~ra.ge pleva.tion of (.3':iD
feet above MSL. (Figure A-2). The UpPer' fvla.hcney basin is the waterstl(:d area
a.bove the outl",t of the upper lake. ["his wa:eY'shc~d is 2.'1 square miles.
The Upper r1ahoney Creek basir: ~s tile' '"atershed be-io,,; the outlet of the
upper lake, but above the inlt:t:~o tile 1m'>ier-13k(:. lbnoff from this
O.5-square-olile watershed enters the creek chann~l il~d delta directly and
th·~n flo\vs into r'13hon.::y Lake. Aver'age Lipper ;~ahoney l>er~k bash <c:l(,Jation
is 1,350 feet above iI1SL. (In some pub 1 ic:aV OriS Upper iiahoney Cr'eeKmJ'y be
referred to as Falls Creek.) The Mahoney Lake drainage basin, above the
lower creek inlet, is 3.1 square miles. The entire ~ahoney Lakes drainage
ba~;in is 5. j' square miles with an average eL:"lation of 1,"130 fe·,:t above MSI_.
fhe nearest climatological station with the most similar meteorological
conditions to those of the pruject area is locat~d at the Beaver Falls
(Figure A-l) power plant east of Ketchi~an. Much is known about th~ Beaver
Fal is basin, so that this basin is often used in comparison with thr:' 1esset'
known Mahoney Lakes bc:.sin. The Beaver Fans basin shares a cornmon divide
with Mahoney basin and appears to contain similar topography, geologic
features, and exposul"e. However, the higher e'levdtion of the Upper' ~lc,honey
basin would indicate that the climate in tilat arC:a WOUld have higher total
precipitation, less temperature extremes, 0nd hiqhe r tot21 snowfall th~n
tne beaver Fctlls basin. No pel'lilanent snowpack exists -in the dt"ainaw'
areas, although considerable snow is received during the wlnter montns.
/\ltilouqh th(~ climatic data from t3eaver Falls are fairly r{~p('esentat:';iC' of
sea level conditions near the project area, 10wer temperatures and qre~ter
pn~cipitati()n ·;'!mounts 'tJi-!i occur OV(~t· ::h(~ higher UiJpe r Mahon'~y basin.
KETCHIKAN AREA
FIGURE
A-1
4000
10 20 30 40 50 60 70 BO 90 100
Percentage of basin area below elevation
Figure A-2. Percentage of basin area belaw an elevation
A-3
Streamfl ows
Runoff characteristics of streams in southeastern Alaska are representativ~
of the maritime influence. This influence greatly increases the runoff per
square mile and also changes the timing of high nood flows from those
experienced in central or interior Alaska. While fiood peaks occur in ~1ay
and June due to snowmelt runoff, the yearly ~aximum peaks generally center
around October. No0mally~ about 75 percent of the annual runoff occurs
dUY'ing the 7-monU period from May through Novembe1~. 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 fim" cou;Jled w~th some subsurface
or interflow. Therefore, short dry spells have the effect of generating
E'xtremely low streamflow. Streamflow distY'ibutions for the period of
record at five stream gaging stations in the area are qlven below.
Table A-I
Monthly Streamflow DistributiGn as Percent of Annual
Grace Fish [3~aver Mahoney
Cre"'.k Creek Fa 11 s Creek
t~onth ( %) t%) ~--(%)
Oct 14. 1 14.2 13.6 13.9
Nov 10.4 n .4 11.6 10.5
Dec 7. 7 7.9 7.9 6.7
·Jan 6.2 6.7 5.5 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 5.2
May 12.2 10.4 12.0 11.0
Jun 10.9 10.0 11.4 12.3
Jul 7.9 7. 1 8. 1 1004
Aug 7.2 6.8 6.0 8.5
Sep 7.5 8.4 8.5 9.0 ----
Total 100.0 100.0 100.0 100.0
--=-:..=-~--='
CL IMATE
Temperature
T~nperature records are not available for the Upper Mahoney basin or the
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 u~ually confined to relatively narrow limits as a result of the
dominant maritime influences .. Although variations between maximum ana
mini'nun! temperatures may vary as much as 40°F during clear periods, the
differences between normal daily maximum and normal dai-:y minimum
A-4
t~lTIperatures ranqe frc:1l as Ii tt l? ,}C. S\"~' ,:: :J~ce!Tlber r.c, around 16°F in
.June. Seasonal variation'; ra'lg~ from a ;T!,:dlth':y Ilurlnal tempei"at:.;re of 35°F
in January to 58°F in July for the M&non~j Lake basin. Extremes of record
Cover a range from the maXlmum 8Sor i~ June to tne mi~imum of lOF in
January. Extreme max imu,n t~e0ding:-; al:ovp. 8!)cF hc!v':' occunea in ~iay tnrough
I\UgIISt. Low tempel"ature exh'err,es of a,',)",il,j OaF hav~; JCCUl~red in both
J,lnfJary ilnd j)r~cern!)er. DW'inq peY'1ods "f caLi: IV 1ight winds, local
temperature variat~ons a 1',°2 frequently 'le,!, 'OnOi.lli.:ed, Variations'n local
radiatilJn and ail" di'ainage produce 'Hid;:; d;f(en::ncl~<:;jn temperatu"'es.,
particu~arly !Jetweerl upland or S'iOp:riJ a r e'1',. :.i!d the flat, low ten:tin,
I'lhichis greatly affected by air c~'Jin;}(:e fe'(}', :liSJh elevat'ions.
Records t)f actual preciiJitation rnea';!J\':,:nencs ,,,t ':,:'1:: prDPos{~d Siti-= are non-
eX1stent. The.5.1-square-rnile dra~na:)i~ 0CJ.sii~ -:<"/(: Ule disc/large C;a(;':,
locat",o on Mahoney Cree~ p('od~c>c:s ·1(1 (j'iya~jO '" ,'l',~ i flow cd; 104 cUlj'!e feet
per second (cfs). Not consid,::rinq ';'iT;i;:-,)'.:'Ll(,;l, r.\li1IJut,"'~\nspirationo or
lnter'ception, this averuse annlj,:il (():10": t';:,!at.,C'c t.o an average annui:':
precipitation over the enti"e basin ~f 2~ 1 ~st ?4H inch~s. Rai~fa)l
records for [)eaver Falls indic3te Jr. ~\t':rag~ annlial precip;tatio" 01"149
inches for the period of Y';}c)I'cL ;'iv'~ ;L1\:ey' FC'.' I', qil.9,=IS locstel:in ~lIe
saille area, Dut r.ear sea i evr·j , fi,e r,'j jfl f~" eva i.: i ()n ,)f thc: rv,lho;'l(~y L,:~~::,'s
basin and ol'ogr'apr,ic eff,::cL ; \3, \,2 0. m;,r:":E::lj in1' II,ef'C.~ on ,ne pre>ciplt.),tion
i:l that lOCal area. f~lsl)) ne::,:::u:;e thG 248 inci-,e~) pe;' year rep"i~'J.:'n;:s ct::
dlJerag'~ conu i t i on, it is apparent nlat trV? i.JPD~r Mahunc;v b.::,s ~ n reu,'i VCS
c()T;iderably greater amounts J( pr,,~cipitai: iT']. f~)r iij(:tanc~,;f the low"r
MJhon'~y basin is assun,,:::d to ,'·,~c2iv>2C.i]i.2 1~9 ';nches :::hd;acteY'is~~\c or Beavey'
idl1S, the 2,1-squ0('e-rni1~ area of the Upper' ~Ji3;l,)ney ~Jasin v.'Ould rlave to
receive precipitation a:nounts iii :~'\c.::::::~':; "f li'lOnchE:c r~Y' :v~ar. '~'[.viously
this is rl gross appr,')xirleJtior.; howr~v'::", tnF.' ';:i~Dijc[~tions O,r'e valid, June
through August marks th~ period of 1;~~test precipit6tion, ~ith monthly
av·~rages at tne Hca'fer Falls st-3ti~l' ~'j'''Jlr:l;';-'liTI about 2 to 11 ;nc(-l=;s.
Aiter Augu')t:, monthly amounts inC~"e1:::: ,j()t, ': (', D(.:tiik of 32 iri':he:, is ;"eaChed
'in Uctober. ivlonL,ly averag,=s t.i)en tSild to (icc'I'ine [,'Ofi1 ilJoVe!nbel' to ,July.
The heaviest stOY',T! prt:·( ;pitati::-n ,::'IlGur.ts ir: th0 .::,outh'.~rn coastal creas arlO:
the result of foil and \N~nteY' storms. J~ S\;!1lID)t"y \;1 climatological cata
fro(n Beaver ~alls is giver, in FigLP'f::. 1.1,<. "~i(;llil1nin V2Y'SUS Sea L.e'v':'l
Kainfa'll MeilSUrelf!ents [)U;'~'lg Stor!!l') c..t Jur"t:,~I, ; ... h':~kd.," by Murphy Y"(i
Scharnach, (1%5 W~ster'll Snov-I C;,'nfe'rt:nr;e) ,'> ")reci~);t"ltion variatio;'1 .v',til
~levdtion study, specifici'Ally 5,:10\\!" tne eieViiCio(, }",'cci:)lcction
relatior:ship between JuneiJLi ':,0a !'~v;:.:l: an(j ;¥ILJIHle~~l (3,400 feet) (:=-iqure
A-£1). i\lthouqh this study ',d"in t<,e JUnb,U ~it (,j, ;,hc r':::lAtionsh;p is
h~ii:.>v(~d to upproxirnat<:: t!'l'~ telationsflip ~i'::L""'c::'2r: t;JI:~ [paver F2.11<::
pr('!>i;'Jitat.'jDn gaje and [lY'0:::ipitc)ti'j, ':;'1 th? U~'~Je;'i:a:',('npy b'lsin.
Figur"e /\-4 indicate'; thi1~ a l)a<;i;; "iiiJ: (:,': c\V'i::('d.'Je el1;:~'JaUun of 2~350 f~:r:t
(::r;p'·r' r'!'1honr~'y) wou'ld have ;'.3~i1:"'S :~(l',\ r"oll:)i1::J.~i Ii oxp~ri,~!~-.::ed at ::':,a
1:v,:>1 (:>':::dvey' ::(j'lis) an!J c1 l)ilsin ~ti~t;i,i a\';:.'('a~,\:. f2 1i2vation of 1,3:)0 f,=2t
(Upper Mahon~y C~~eK) woulrl h~ve :.75 tim£~ thJt of 5navD~ F~11s. Gased on
t his r a \: t or' a. i1 d U1"~ a v e (' ,;, f~l'~ a. i i, 1\, a 1 I)' ' >:' C : fJ 'il',-} t 1 (I:: ~1 f i ~f 9. j: n c :1 (-' s rt t B PW e r
FillL~, it wOdl(; fJC appa('(~11;:' l."'~' 3~'j j'i';~l,l' c/ i:Vl':"~se annUl): l:;l'ecipitiicion
.' --:...~
)::>
I m
STATION
[3eaver Falls
Ketchikan
Beaver Fa 1 1 s
Ketchikan
STIHION
Beaver Fall s
Ketchikan
CLIMATOLOGICAL nATA
MEAN MONTHLY PRECIPITATION -INCHES
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV OEC ANNUAL
13.63 12.56 10.71 8.29 7.52 6.17 5.98 9.93 15.88 23~77 16.77 16.15 147.4
15.06 12.74 12.15 12.88 8.62 7.20 8.48 11.27 15~29 24.77 17.63 l6.18 162.3
MEAN MONTHLY TU1PERATURE -F ' '
32.5 35. 1 37.8 41.9 50.6 ' 57.0 59.4 59.2 54.2 ' 41.0 37.8 33. 7 45.4
35.1 36.2 38.7 43.6 50.1 55.2 58.2 53.9 54.6 47.3 40.9 36.7 46.3
SUMMARY OF CLIMATOLOGICAL RECORDS
Average
GfOUild Temnerature (r)egrees f~_t Annual Average
Eleva-Years Precip;-· Annual
tion of Max;-Min;-Mean Mean Mean tation Snowfa 1'1
(Feet) Record mum mum ' <L~~J!~' Y, ~l.Y Annual .U..!l5::,~E~ iJJlches L --------'------
35 24 88 1 35.0 58.4 45 "~ 14i'.4 97.3
90 64 96 -8 35. 1 58.2 46.3 162.3 32.9
Figure A-3. Climatological data for the City of Ketchikan and the Beaver Falls power plant
4.0
3.0
+->
Q)
Q)
'+-
0
0
0
.---i
c:
0
+->
cO 2.0 >
Q)
LW
1.0
o
1 1.5
Ratio of ;~t;-·lJ.::;u
Figure
"" <, L. '_
t" .
;,:1
II.;
i .
4,,0 _' i,:
.... 1 .. i
:. r~ 2. L i 01'1, ') h 1 ~j
~: jf:~c i! (:~~" LOu
t,::· t'''!:~t~n
i:-t~t ~)
fallon the Upper Mahoney basin and ?6i ir(h~s en ~ne U per Mahoney Creek
basin. In compiling the elevation r~~off relaticns~iD Figure A-5), gaged
streams in two different lccat-ions (souUlern ana east s de of Rev-illagigedo
Island) were analyzed to determine uni~ runoff as a function of basin mean·
elevation. As shown, the basin Gn the east siae of Revi~lagigedo Island
(Lake Grace) had less unit runoff per square ~ile than the basins near
LJpPFT Mahoney on the southern ti p of the is 1 and. If c'i 1 i iff? througll the
average 212vations of the gaged basins on the southern tip of Revillagigedo
Island is extended ~eyond 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 ~10 inches/year) is
apparent. The difference of 33 inches hetween the average runoff and
average precipiation could De at~ributed to eva~otranspiration.
Conservatively, th~n. it can be ass\I,ned tnat whiie the L'pper' Hahoney basin
refJresents an area only 36 percent of the entir'2 i'!iailoney Lakes basin, 43,8
perc~nt of the avev'age annual runoff comes f)'Oi,1 the JPpA" basin. This
results in an avet'age annlJal rur,off)f 48 cfs ~~c~ the upper basin.
/~pp lyi ng the same procedures to tile Upper Mahoney l>'eek ba<,: 'I, an average
~;nit runoff of 11.45U acre-feet per square i)11ie pl'~l" y~-Ji' ,8 cL/yeal' or 215
inches/year) is derived.
An analysis of 3 jea)"s of corllpaV'abh~ str'eai-:Jflo\'J dat?; ;Oc:t(:b":'r 1977 -
September 1980) for the Mahoney Lakes basins lndicates that origi~al
as~umptions conc~rning the precipit~ticn/fl~w r'elationship b~tween the two
are essentially conect. The obse,~v;~d ili'Con annual di'.chargc for the short
period of record at the Upper Mahoney Lake outlet is 40 cfs (estimated at
48 cfs when no data were availAble) 2nd, at the lower lake for the same
period, 83 cfs. Although the observed discharges are lower than estimated,
the upper basirl contt'ibutes 43 percelt (If the discha'rge for the entire
basin as predictet. The lower flows can be attributed to the fact that for
2 of the 3 years o~ record. t~e annual precipitatlon recorded at Beaver
Falls was 23 inches lowe,~ than the ~·3-.lea( average of 149 -111ches/year. For
the other year it exceeded the averdse by only 14 inches.
Snow
Snowfa~l records are not available in the imm~diate vicinity of the study
area; however, snowfall characteristics for the are~ can be descrihed
through a study of the 8eaver Falls records. A trace of s~ow 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 thf? ground atlcM lev l ::1 :: until t"'" -last of Novembel~,
although at higher levels and particula~1j on mJJ0tain tops, a cover is
usually estab-iished ir. early OctoLJet'. Sr10w accuf1F,lation L~SU3.ny reaches
its greatest depth during the first Of ~arch. November, Uecember. January,
and Fel)l'ua1',l have ttv::; heaviest snmifdll, althoiJgh indivldllal storms may
produce heavy falls as late as the first half of Mav. Snow cover is
usual1y gorlf: !,efrH'e the ITiiddle of I'lay, exu:pt at hi~her (21e::vations. During
some winte~s, when temperatur~s are &bove nonnal, there is a great deal of
tilawinq, vJr!'cli caUSeS ':;Iush that -!a.te Y freezes, Th,:,l"? are occasional
i n t e r val s 01 r a i Ii U' (, t f~' e 'c> Z 2; n tog 1 i.J. rei ceo II con t act \<1 -j tnt he q round or
structures.
)::>
I
\.0
3,50Cr---------·----------~----------------------------------------------------------~
Legend
() Beaver Falls Creek
• Ketchikan Creek
3,000 * Mahoney Creek
• Falls Creek o Grace Creek
* Ella Creek
c () Manzanata Creek
o 2,500 (j) Fish Creek ~ ------------~
ro >
Q)
r-
Q)
<1j 2,000 w
S0-
(\)
Q)
rn
ro c:
'r-
ro
S0-
U
C".
(0
~
1,500
~ 1, 000 v
<1J
.;J
..c
C"
'r-
(j)
3: 500
East Side Revi1lagigedo
•
o~---------.;--··-,~j-· __ ~I'~
. Weighted mean elevation for
Upper Mahoney Creek basin
Unit runoff ~11,450 acre feet/mi 2/yr
//
... /~ ,
4~ ... -Southern Ti p
L. ~ ..
Revillagigedo Island
I lieighted fileiJr1 elevation
abbvp Upper ~lahl)ney Lake
~nit runoff = 16.300 acre feet/mi 2/yr
7,000 8,000 9,000 10,000 11,000 12,OUe 13,OO() 14,000
Unit runoff, acre feet/mi 2/yr
15,000 16,UOO
Figure A-5. iJrainage area e1evat-;on vs. imit runofF
17,000
Wind
Wind records are available from the Nationa1 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 5C ~nots) ordinarily hlow from the southeast up Tongass Narrows.
ihese winds ere caw;ed by the shoreward movement of maritime air. Speeds
of 50 to 60 knots ore possible, but extreme gusts are y'are. Surface winds
in the southeaster.l 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 lJelocitywinds probably occur in the area being stiidied.
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
made in the Juneau area during construction of the Snettisham project,
wh~re ~ind 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 Ilydropower 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;
6ccumulations of over a few tenths of an inch are considered rare. From
1,000 feet above MSL and upward, both the 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 penetration in the Ketchikan area will vary significantly from one
site to allother. dependent on such things as the nature of the soil, its
water content. recent geology. and proximity to continental and maritime
1\-10
influence~. In qeneral, there is little evidence of frost penet~ation 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.
Snowslides
In the higher elevations of the study at'ea, portions of the ten-ain at~e
devoid uf snow cover for only short periods throughout the year. It has
been estimated th~t snow depths, as a result of drifting, in excess of 20
feet may be reached at higher elevations. Snows of the~e magnitudes accumu-
late on the precipitous slopes of the drainage basin and at high elevations
above the transmission lirie route until enough weight is accumulated to
ov~rcomethe 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 area 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 tremendbus force. Winds created by displaced air move with
blast velocity and are capable of destroying blilldings because of the rapid
change in differential preSSd)'eS 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 avalancne
threat.
STREAMFLOW RECORDS
Spveral potential hydropower sites in southeastern Alaska have attr3cted
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 StreamfloVi Record
Stream discha~ge records are available throughout 1915 to date 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 t'\-6.
Table A-2
stream Gaging Siations
Dra'i nage Area
Station (sq. miles)
Grace Creek near K2tchikah 30.2
Manzanita Creek near Ketchikan 33.9
Ella Creek near Ketchikan 19.7
Fish Creek near Ketchikan 32.1
Mahoney Lake Outlet near Ketchikan 5.7
Upper Mahoney Lake Outlet 2.1
near Ketchikan
=========
Period of Record
Oct 1927 -Sep 1937
Aug 1963.-1969
Oct 1927 -Oct 1937
Aug 1947 -1967
Oct 1927 -Sep 1938 .
Oct 1947 -Sep 1958
Jun 1915 -Oct 1935
Oct 1938 -Present
Oct 1920 -Sep 1933
Oct 1947 -Sep 1958
Oct 1977 -Present
Oct 1977 -Present
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 strea~flow 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
+-'
())
C'J =+-.
t
... ,_ 40.
c
Figure A-6.
1S71 197fi
Year
Gaged and synthesized streamflow at Mahoney Creek
Octuber
y 1.lh
(J.W)
11
.1S
J1
l(j
''<l~""
?n
10
1 S VI n <;
r ,sh (rl:'~k cfs/i\i\2
In ?" J0
11 1', i'l 1'1
r"srl Cn'~'~ rf;-,/I,Ji'
Figure A-7. Correlation analysis --Mahoney Creek vs. Fish Creek
1\ III
,:::---~-==-=-..:=:'=--=-==..:.=.:= :.====--~=--=
Table A-3
Mahoney Creek COITel at i on with Fish Creek
Cor~'elation
Mahoney Creek, r·· f-, ~ 1 S, Crpe l , I'+S) -.~----~'--~~-Coefficient
October ~~ahoney Creek flows = 1."17 Fish Creek flows +4.01 0.83
November ~lahoney Creek flows ::: 1.30 Fish CreeK flows -0.73 0.90
December Mahoney Creek flows ;::: i .46 FIsh Creek nows -3.43 0.98
January Mahoney Creek nows -' "'J I • J.J Fish Creek flows -: • 25 0.96
Feby'uary Mahoney Creek f 1 O\~s == : .?9 Fish Creek f'iows -1-'I (J 0.96
March l"1ahoney Creek f'lows = 1. 30 Fish Cn~ek flows -1.46 0.91
Apri 1 Mahoney Creek flows = I,d ;:] sh Ct'eek flows -0.85 0,90
May Mahoney Creek f 1 OVIS .-1. 20 Fish C:,;,t='k flows +2.94 0.90
June Mahoney Creek flo\1i5 = 1 • 1 J Fish Ct'eek f 1 O\vS +10.06 ().81
Ju 1 y Mahoney Creek flows == 1.47 F '; sh Cr;::ek flows -6.52 0.88
August Mahoney r:reek flol'ls I o5! Fish C ret: k f'iows +4.85 0.91
September Mahoney Creek f!(lWS = ~ .2d Fish Creek flows +2.25 0.93
Because of 2 years of missing recurds at Fish Cr2~k, additional correlations
with Ella Creek Were necessary to complete the ext2nded record. Since
these correlations .are of onlY minor significance, they dre not. included
here.
The 2levation of the Upper Mahoney basin (average 2,350 feet) contrihutes
to the abnormally high amount of precipitation that falls over the basin as
well as the seasonal or monthly variance in rJnoff distribution. As shown
in Table A-4, the winter precipitat.iun genera'llyexceeds the summer
. precipitation. However. the I'!inter precipitation in th~ Upper ~Jiahoney
basin is mostly snow, which accumulates durirq the ~inter and melts from
late spring through summer. contributing greatlY to the hign summer
discharge reflected in the Mahoney Creek gaqing station records.
'I, -1 ~;
Table A-4
Average Monthly Precipitation and Runoff. Mahoney Lakes Basin
January
February
March
Apri 1
May
June
July
August
September
October
November
December
Annual
Mahoney Creek
Period of Record
Avg. Precip.
(i nches /month)
14.4
12.5
11.2
12.8
26.5
30.2
26.0
19. S
22.S
34.4
28.7
20.5
259.S
Mahoney Lakes Basin
Monthly Runoff (%)
6.7%
4.2
3.8
5.3
9. 7
il.7
10.0
9.0
8.2
13.6
9.9
7.9
lOO.cr~
Seasonal runoff from the Upper r~ahoney 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 oasin 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 Dasin, 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
l"ecnrd is estimated to be 22 percent of the flow at the lower gage.)
When the Long Lake 'nonthly percentage flow distribution is compared with
Speel River, monthly flow distributions for the Mahoney basins, as shown in
fable A-5 and Figure A-S, resulteu.
,L\-1 6
Table A-5
Percentage of Total Monthly Runoff Attributable to Upper and Lower Basins
uctoter
November
December
,January
February
March
P,p r i 1
:~ay
June
clu ly
IAuqust
Septl'rnber
/\verage l\nnua 1
From Upper Mahon~y
____ J % ) _____ _
46~~
30
28
25
22
{'f
30
40
60
jj
43.8%
1/ Inc 1 !JlJes Upper rlJahoney Crc:e:< bas in.
From Lower Mahoney 2/
54%
70
72
75
78
?6
70
60
45
3:;
40
The (:::tfect of this adjustment would be to general iy reduce the winter flo'ds
and increase summer flows in relation to the distribution indicative of the
measured flow of the total basin.
Sedimentation and Water Qual~y
AltlloulJIl sediment and water quality data For the Mijhl)ney Lakes b2sin are :lot
cJva'i"ld[lle, the drainage MP.j c:-'a:"acteristlcs of ail the potentiai sites
lndicate a very low rat~ of seaiment proriuction. The upper area i~
predominately covered by muskeg and no glaciers or permanent ice fields are
in the area.
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 ijcre-
feet pel" square mil,:; per y~ar, or'jess. This c:orrespond~ to an annual
sediment inflow to tile lJ.:>per Marloney '"<"sen/oir of only O.2i acre-feet per
year, Wilich is a negligible amOL.nt. nl2tt: are no changes to sediment yield
as an efipct of fJossible tutUt'!:' 'land usc. Tne area proposed for the i\';ahorey
Li1kes pruject is void of an) i,l::1rketable t-irn~)f;r. In view of the low sedirn2ii-
tac lon rate and projected locati:Jn of the power intaKe worKS ar,d dam, there
a,t' no anticipated Se(jjGlent lJrobleIT1S assCiciat,:~d vlith r~ar](1n(~y Ldke<; project
fi'Jtn'I--,'"
T!l'~ nOtH,a] iligrl l'2lative hu;nicJHy, hlCj!1 per;.,;en";(Jge of ovc~'cc·~,t Jays,
SCJ('city of tt'ees in the upper lJosin, and r',"lotiveiy cool clilnate prec ude
an; appreciable jJercentag(> of 'va'.:.er ioss fre:!i evapotranspiration.. Est mat~s
Mo. 17
:::
0
r-4-.
r-(0
:::J c
C
10
~
c
OJ u
~
OJ
0...
IS
14
13
12
11
10
9
8
7
f
!:; ..,
4
2
2
1
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Figure A-B. Monthly distribution cf annual flow from
Upper Mahoney and Mijhoney Lakes
~ c ,) r\-10
of flow were based on records frolll existing ~Jr historical gaging stations
near the project area~~. These records ;'eflect any past evapocation. and
for these reasons, no corrections were made in the runoff analyses for
evaporation. The difference of 29 inches hetween the estimated average
precipitation at Upper Mahoney and average rUilOff hom Upper Mahoney could
be attributable to evapotranspiration. As 3no~n in Table A-6,average
evaporatioY] losses totaling 15.6 inches were oDserved at the Lluneau airport
from May tnrough September; This may be sornewhat. indicative of evaporation
losses that may occur in the project ar2d.
i~ay June
3.31 3.65
-------------------
Ju 1.1:'.
3.85
Table A-iS
Evaooratian L1SS~S 1/
( inChes)
Septc:cmber
1. 40
1/ Juneau airport, 1968 -1978.
FLOUD Cfl.L\\{ACTER ISTICS
Snow,lIe It Floods
Iota 1
15.6
The proposed project site has flood peakS in the early summer that are
predomi na te ly from snowme It runoff. Tric magn itL:de of the sPyj rig fl ood
peaks is dependent upon three conditions: (1) the amount of accumulated
snow, (2) thE: temperature sequence duripg spring melt, and (3) the amount
of precipitation. A large snowpack aver the basin will give a large volume
of runofF diJri ng the sjJri I1g and SWnlller; but, if ttle temperatures increase
gradually, causing slower snowmelt, the flood peak will be just slightly
above normal. However. if trle earlY sPY'ing i::, colder' than normal arHj the
temperatures rise rapidly for a prolonged period, the flood peak will
probably l)2 extremely fligh Witll the duration of flooding ilependent upon the
tota 1 snowpaCK.
I~ain ~loods
Rain floods produce the highest flows, which usuaily occur in the fall
hetween late Auqust and October. The flood peaks are quite sharp due to
the fast runoff-caused by the steepness ~f the terrain and the low
-infi itratlon losses ineo the LJnderlyinq rock.
Past Floods
The maximum instantaneous recorded disch~rgcs from six 929in9 stations in
the area 5re provided in Table A-7.
A -19
TableA-7
Maximum Instantaneous Recorded Discharges
Watershed Size
Station. Discharge (efs) (mi 2 ) cfs/mi2 Date
Grace Creek near 3,990 30.2 132.1 4 Sep
Ketchikan
Manz an ita Creek 5,820 33.9 171 .7 14 Oct
near Ketchikan
Ella Creek near· 1,.720 19.7 87.3 7 Dec
Ketchikan
Fish Creek near 5,400· 32. 1 168.2 15 Oct
Ketchikan
Mahoney Creek 2,530 5.7 443.9 2 Feb
near Ketchikan
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
Annua 1 Peak
Water Year . DiSCharge (cfs) Date
1923 1,850 31 Aug 1923
1 g28 762 12 Oct 1927
1929 1,460 21 Aug 1929
1 g30 1,920 8 Nov 1929
1931 2,400 2 Oct 1930
1932 1,250 13 Oct 1931
1933 1,090 20 Sep 1933
1948 1 ,210 31 Aug 1948
1949 1,260 21 Sep 1949
1950 1,640 5 Sep 1950
1951 970 11 Ju n 1951
1952 866 7 Oct 1951
1953 842 20 Oct 1952
1954 2,530 2 Feb 1954
1955 1,640 6 Aug 1955
1956 1,530 20 Oct 1955
1957 838 25 Dec 1956
1958 1,350 1 1 Apr 191)8
A-20
1966
1961
1930
1961
1954
Peak discharge frequency at the Mahoney Creek gag~ is shown in Figure A-g.
Because of thesmal L potentia"' for heavy monetary loss if flooding \'iould
occur, 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. 1\ summary hydrogtapll of t,le Mahoney Lakes basin,
which provides minimum, maximum, and mean daily flows as well as maximum
instantaneous flow, is provided on Figure A-10.
Probable Maximum Flood
Table A-9
Mahoney Creek Flood ~requency
Return
Interv&1
(y;~ars )
r, r..
~)
10
20 so
100
r"lood
Magnitude
(efs) __ ::...._~_"M
i ,304
1,/85
;;, 1 ?!j
2.450
2,922
3,311
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 da:a 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 hasin, 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 prov~Jed in Table A-10.
J~"-21
III
~
> U
I ." ~
N .~
:::
0
~
LJ...
6000
5000
4000
3000
2000
1000
900
800
700
600
500
400
300
200
Exceedence frequency per hundred years
98 95 90 80 70 60 50 20 10 5 2 1 0.1 0.01
Figure A-9 .. Peak discharge frequency at Mahoney Creek
NAfilCH
Period of Record: 10/1/22 -11/31/27,
111/28 -11/31/47. 1/1/4B -2/28/58
Ordinate \'ah~s between 1200 and 2400
have lJE~,n delpted. HO'iever. respective
flows have t'"f.~ shown in parenthesis.
Figut~e A-lO.
o
Month
Sun!l1!a ry hydrograph of the Mahoney La kes basi n
Tab 1 e A-'W
Rainfall Distribution of the Probable Maximum Storm
Accumulative . Incrementa 1 Accumulative Incremental
Time Ra i nf a 11 Rainfall ·Runoff Runoff
(hrs) (inches) (inches) (inches) (inches)
, 1 0.6. 0.6 C.O 0.0
2 1.3 , 0.7 0.2 0.2
< 2. 1 0.8, 1.0 0.8 '-'
4 3.0 0.9 1.9 0.9
5 3.9 0.9 2.8 0.9
6 5.0 1.1 3.9 1. 1
7 6. J '. 1.1 5.0 1.1
8 7.9 1.4 6.8 1.8
9 9.3 4.0 8.2 1.4
10 13.3 2.5 12.2 4.0
11 15.8 1.2 14. 7 2.5
12 1 7.0 0.9 15.9 1.2
13 17.9 0.6 . 16.8 0.9
'14 18.5 0.5 17.4 0.6
15 19.0 0.5 17.9 0.5
16 19.5 0.5 18.4 0.5
17 20.0 0.4 18.9 0.5
18 20.4 0.7 19.3 0.4
19 21.1 0.7 20.0 0.7
20 21. 8 0.7 20.7 0.7
21 22.5 0.6 21.3 0.6
22 23. 1 0.6 21. 9 0.6
23 23.7 0.4 22.5 0.6
24 24. 1 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 maiimumstorm.
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 discharge for the
Upper Mahoney basin are provided below.
L =
H '"
S =
Tc =
2.2 mi = 11,616 feet (channel length)
1,400 ft (diff. el. headwater to site)
H = 1400 ft = 0.1205
L 11616 ft
LO.77 = 0.0013 (11.616)0.77 = 0.397 hr.
SO.385 (0.1205)0.385
A-24
A = 2. 1 mi 2
Q = 1. 00 in.
D = 0.5 hr.
Base Time:
Time to Peak:.
Peak Discharge:
Tb = 2.67 Tp = 2.67 x 0.49 = 1.30 hr.
Tp
Qp
D = 2. +
= 484AQ
TP
0.6 Tc = 0.5 . 2-T
484 x 2.1 = = ·-0:49---
0.6 x 0.397
2074cfs.
0.49 hr.·
The 24-hour PMP was applied to the unit hydrograph, which results in a
probable maximum flood of approximately 5,000 cfs (Figure A-ll). [ecause
the dam is designed to be overtopped, a standard project flood (SPF) of
2,500 cfs was us€din 1 ieu 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 an the discharge-surCharge cu~ve (Figure
A-13), the surcharge resulting from the SPF at the spillway with weir
lengths of 100, 150, and 200 feet WJuld 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 he·ld
temporarily because it is all above the wi'?;' crest. The outflow
hydrographs for the SPF, with a wier controlled lake outlet, show how
storage is temporarily held (Figure A-12).
Area Capac ity
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.
A-25
~) c,
5000
4000
VI I
t; 3000 l
'-;
o
2000
1000
o
n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 l~ 17 18 19 20 21 22 23 24
Time (hr)
Figure A-II. Probable maximum flood hydrograph for the Upper Mahoney basin
; 1
• -• I .
_. I
f •.
l-"
I ' .
I I .
2500
2000
Ul
4-l
U
4-l 1500
4-l
)::> 0
I ~
N ~
-...J rx;
1000
500
----------.---------~------~.------------------------~----------------·~·----------l
1 2
Inflow and Outflow Hydrographs for the Standard Project Flood
Inflow
:Outflow 200 Ft. Weir
. i:t~til~w iso Fi: Weir:"-
O~_~f1~~ )00 Ft. Weir
3 4 5 6 7 8
Hote: Outflow hydrographs for we1r widths
of 100'. 150'. and 200'.
,"
~-~------
9 10 11 12
Time (hr)
13 14 15
Figure A-12. Inflow and outflow hydrogLaphs for the standard project flood
I
16 17 18
o
200
150
100
50
o
1800
1.5
2000
Surcharge (feet)
3.0 4.5
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
..........
Ul
4--
U
2500
. j
,
2000
1500
+
1000 -~-------~-~-
\ • I
600
-I
-j
f ,--
i '
-I
i
i
1 1
-+ .~--+--..... -.-------.-+ .. -.-.---.~----. t-
.---;-I ~ -,
__ . ____ , __ . ___ .. ___ .J ...• .,..
, I
-r .
o------------------~------~----------------~--------~------~~---o 2000 4000 6000 8000 10000 12000 14000
25
STORAGE t + 0 (5FD)
Figure A-14. Storage vs. discharge for weirs on Upper Mahoney Lake
• 8 1" 11 12 11 15
StorOV" r.. .. c1ty-l00Ci Acrt F_L
Figure A--15. Area c? par:ity clJ¥'ve fD~' U~per ~1a honey La ke reservoi r
I
~
~ 1": 400' I
4iJ'?S" 0"; ==':00' i
I
. er Mahoney Lake Figure A -16. Upp
,
I
!
~ ~----~,,--.-.-----~-----
<.f\
4--
U
-~
Exceedence frequency per hundred years
Figure A-17. Low flow frequency curve for the Mahoney Lakes basin
APPENDIX B
FOUNDATIONS AND MATERIALS
GENEr:AL GEOLOGY
REGIONAL GEOLOGY
SITE GEOLOGY
SEISMIC ITY
PREVIOUS INVESTIGATIONS
FOUNDATION CONDITIDNS
lJarnsite
Lak~ Tap
Penstock Tunnel
Portal
Surface Penstock
Powerhouse
MATERIAL SOURCES
Powerhouse Stream
Darnsite Qua.rry
Disposal Sites
CONCLUSION
APPENDIX B
FOUNDATIONS AND MATERIALS
Table of Contents
Figures
Page
B-1
B-1
B-5
B-8
B-13
8-"i3
B-B
B-14
8-15
8-16
8-16
8-16
8-17
8-17
6-17
8-18
B-18
B-1 Earthquake Epicenter l"lap B-2
~-2 Regional Geology 8-4
B-3 Site Geology 8-6
8-4 Stereographic Plot of Primary Joint Attitudes 8-7
8-5 Geologic Section Through Tunnel and Penstock 8-10
A "I i g nrnent
B-6 Modified Mercalli Intensity Scale 8-12
Table
B-1 Maximurn Peak Bedrock Accelerations
at the Mahoney Lakes
Appendices
APPENDIX B-1 Tests on Gravel frorn the Powerhouse Strearn
APPENDIX B-2 Tests on Darnsite Quarry Stone
8-11
GENERAL GEOLOGY
APPENDIX B
FOUNDATIONS AND MAfERIALS
Southeastern Alaska is part of the circum-Pacific "ring of fire," a belt of
seismic ~nd 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 intrusi0n, and local
disposition of volcanic and sedimentry rocks.
FauHing has played a major role in the structural development of sO:.lth-
eastern Alaska. Large scale faulting, particularly right lateral st~ike
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
southeaster'n Alaska's inlets, waterways, straight valleys, and coastli:les
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
metall10rphi sm 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.
o
o ~O
o
55 0 o
o o o
o
o 20 40 60 MILES
~I ====~~I~~==~~
50 100 KILOMETERS
o o
No-,,~r I
""-
,5<l1\
""tufWl1do
klan'
Lulul '
.\ 0 Or?l\ '\j Cap,~x
o
Langara I
•
~OS""J"PI
,~
I
Tal .. ,.ph I
cr •• I<.ry-/
[B)~~1r~~~
o
ENTRANC
RostPI;
::r.
\TI
n
\ ",.;/
~~;; ':P
;
I
\
I
....l,
\TI :\'~ GRAHA ¥O
I
I C~Ball
\ o
0
I
<"'"
ISLAND ;'
1330
Vl
....l,
'" ':P
o
Stephau! ",
,
pr~Jco/t 1 . K.tnfled)
porCk£r
., JjJand
-\'
lsltmd ,
, ,
GOJch,,,1 Pill
Is/ant
McCauley 1
y~JaJ Banks 13 s/and
• • •
LEGEND
HIGH ANGLE FAULT
THRUST FAULT
uotted where concealed;
queried where uncertain
_____ LINEAMENT
.,...
IiIiiI
• MAGNITUDE > 8 ... MAGNITUDE > 7 and <8
• MAGNITUDE > 6 and <7
• MAGNITUDE > 5 and <6
--O-MAGN IT UDE <5
or not determined
Note: Includes known or inferred events
from 1899 to present.
References
Adapted from Berg and others, Geologic Map of the Ketchikan
and Prince Rupert Quadrangles, Alaska, USGS Open File
Report 78 73A, 1978; Berg and others, Structl!!:~lements
of Insular Belt and Coast Ranqe Plutonic Complex near
Ketchikan, Alaska, USGS'Circular 751-B, 1976; Lemke, R. W.,
Reconnaissance Engineerin..9.<:;~!<>gy_o_f the !<etchikan Area --
USGS Open File Report 75-250, 1975; NOAA Earthquake Data
File for Epicenters to a Radius of 200 Km from Ketchikan,
1980; Pacific Geoscience Centre Earthq uake Epicenter File,
1899 -1977, Sidney, B. C .. Canada.
EARTHQUAKE EPICENTER MAP
FIGURE
UI,."., c.a
fII~
AIMI<a DIoIrIct
_IVR. Alii) "A __ S 1111 ALASKA
SOUTHIAST HYDIIOILICTRIC ~OWIR .NTIR •• B-1
AG-FPP 2265-83
The region within about 12 miles of tne project site contains three
tectono-stratigraphic terranes that generally trend northwesterly. The
terranes from southwest to northeast. ate the !\.nnette 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, tne Arlnette subterrane occupies
the extrerne southwest corner of the map. -d-li~. subterrane cons i sts of a
heterogeneous assemblage of Devonian age and older intrusive, extrusive,
clastic, and carbonate rocks. The assemDlaye records episodes of volcanism,
magmatic intrusion, and sedinlentatlcn that b~gar early in the Paleozoic
era. The subterrane has been complexly deformec and metamorphosed.
The Gravina-Nutzotin Belt consists Jf upper Jurassic to ~ower Cretaceous
volcanics, sediments, and dioritiC:l::; iJ:t((~fTiafic plutons. This assemblage
has been identified as the remnants of 1 collapspd uppe( Mesozoic volcanic
arc. Regionally, it is metamorpf,oseo to gi~ec1,sch-ist facies and is folded
into soutnwest converging, lo(ally refolded isoclines with axial surfaces
dipping moderately northeastward.
The Taku terrane, within WhlCh the project area is located, consists of
upper Paleozoic and lower Mp50ZJ:C volca~ic and sedimefitdry rock~. The
terrane is intruded by upper Cr~tacEOUs aikes, sills and stocks of
granodiorite, a bathol ith of CretaceolJs qUdrtz diorlte, and othey' p"utons
ranging in age from Late Jur~~sic to Miocene. The terrane is ch2racterized
by metamorphism increasing northeastward from greenschist to amphibolite
facies of upper Cretaceous age and older. Locally, there is contact
metamorphism near the edges of p1utons up to the hornblended-
hornfels facies. Structures include northeast di~~inq thrust faults cut by
younger high angle faults. The stratified rocks are complexly fo~ded lnto
southwest overturned to recumbant folds and locally refolded isoclines.
The northeast boundary of this ten(',;w is neal~ Bellm Canal, where it is in
contact with elongate stocks of qJartz diorite 2m~laced along a Mesozoic
shear zone that is the (~ontdct between the l:"KU terran2 and the ajj acent
Tracy Arm terrane.
Surficial deposits include drift, elevated mar'ine deposits, alluvium, f~n
delta deposits, beach deposits, talus. ~nd landslide ~ebris. Faults and
lineaments are common throughout the area and many topographic features
reflect these structucdl e-Ie;lents. SOllie of the nneamf~nts are associated
with jointing and foliation planes tnat have been emphasized by glacial
scour.
Four major structures in the region ai'e the Fairweathet'-Queen Cha\~jotti~
Islands fault system, the ChathJm Str~jt fault system, the Clarence Strait
lineament, which may reflect faulting ~long all or part of its len~th, and
the Coast Range linement, at least part of which is the result of
faulting. Clarence Strait and ChJ.thar. Str'ait faults !T;av be cQl'tinuations
of the Denali fault syste~ of Southcentral Alaska and are, ~s such,
associtlted '1ith the North Pacific SUbduction zone. kecentinvestigations
indicate as much as 120 miles of total right ~ateral movement. This is
based on offsds of rnajor featur'2s on O[.::.1,)::;itc s-jde::; of the L:lul;~s.
II~~~'\ .. I .. . , .
I ,.~
~ \' ..
t ,
·1
Qu
QTv
Trng Im9d
Kg Kpq
Kum
KJ5 Kjv
LEGEND
CORRELATION Of MAP UNITS
QUATERNARY
QUATERNARY
AND TERTIARY
TERTIARY
CRETACEOUS
CRfT ..... CFoU ... r >\
CRET ACEOUS
OR JURASSIC
TRv Upper Tnlule
TR~v
TR lASSie
M7.Pzc. t¥1 zPrd Hl.Pz~ MzPzv MESOZOIC OR
UPPER PALEOZOIC
Pzm
PZV
Qu
OTy
Tmg
Tmgd
Kg
Kpq
Kum
KJ~
KJy
TRy
TR~y
Mz.Pzc
MzPz-d
MzPz~
MzPz.v
rzm
Pz.v
*
" Older
UPPER PALEOZOIC
PALEOZOIC OR
OLDER
DESCRIPTION Of MAP UNITS
Gi_ACIAL ALLUVIAL, AND T"LUS DEPOSITS UN
o VIDEO {QI.Ulllernlryl
A~DESITIC AND BASALTIC ROCI(S
(Guarte,.-nllry and TertIary)
GABBRO(Mlocenej
GitANDIQRlTE (Miocene)
MfTAMO.PHOSED BIOTITE HORNBLENDE
G~ANODIORITE (Cretaceous) AI~ IncludH
qUlrll diorIte and lu,oclated rocks
PORPHYRITIC BIOTITE GRANODIORITE (Cretilceous)
UL TRAMAFIC ROCI(S (CreUICeous)
MET ASED IMENT AR Y ROCII; S (Lowt!r C rt!taceous
IC Uppt!r JuraUlc)
METAVOLCANIC ROCI(S (Crt!taceous or JuraUIC)
CHAPIN PEAl( FORMATION (Upper TriaSSIC)
BOISOI!II' lind minor andt!lililc pillo .... nOwli and
brt!ccia With liubordlNlte luff and tuffaceous
li",elilone. Lt!nst!s of se,jllt!t!ntary rocks Intt!rbedded
.:Ih Iht! volcanic rocks
METAMORPHOSED SEDIMENTARy ANO VOLCANIC
ROCI(S (Upper Trlau,,:)
METAMORPHOSED ROUNDSTONE CONGLOMERATE
fMt!sOlOic or Upper Paleozoll:)
METAMORPHOSED DIORITE, QUARTZ DIORITE,
AND CABBRO (Met.Ozoic or Upper PaleolOocl
METASEDIMENTARY ROCI(S (Mt!SOIOIC or Uppt!r
P.)eoloic). Stipplt!d Ireas rt!prt!sent hornft!ls
~ETAVOLCANIC ROCI(S (Mat.Ozolc or Upp.r
p.laJloic)
MARBLE (Uppar Paleololc)
FELSIC METAVOLCANIC ROCII;S (D.vonlan or old.r)
SYMBOLS
Contact. APpro.,,,,al.ly local.d. doll.d wher.
cone_led.
Hlgh-angl. fault shoWing dlrecllon of dip. wl'o.rt!
D.shed wl'ot!re Inferred, Ootlad wher.
conc.aled.
Met.lftOrphos.d -"VUli! f.ull 'nft!rred from strlllgr.pl'olC
.nd structur.1 r.l.hons D.shed where conct!ltt!d.
que".d wt.rt! .. s~ed S.wt •• th on upp.r pl.lt!
Regional Slr""cl""r.s (showing trt!nd of •• ,.1 s""rfact!
----~ .nd dlractlCln of plung.)
Antiform
Synform
Strike and dip 01 folillion or SCh,slolity
Inclined
I( Ar Dlt. S.""pllng Loc.llty
Reference Ad.pled frolt! Ceologlc Map 01 8.rg
and oll'ot!rs (1.71) USGS Op.n F,I.
Report 78-7lA
......
IiiIiiI :a.:;r=-
-DIoIrIot
REGIONAL GEOLOGY
"In ... AND HA"_I I" ALAI"A
aOUTHIAaT HY~LICTItIC ~OWIIt .NTIIt ••
FIGURE
B-2
Major faulting is common throughout the area ana 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 GEOLOG Y
As shown on the site geology map. Fi~0re B-3, the project site is underlain
by two major rock units. Tile b!llk of t::~ ~;ite, to the west and north of
Mahoney Lake, consists of steeply dipp~n9 s~~im2nts (Mzp zs ), which have
undergone greenschist to hornblende-hor~f~ls gt'ade metamorphism. The
proposed sites for the lake tap, th2 tU0nei, and the dam a~e all within the
metasediments (metamorphosed sedimentary 'JC~s), which have been c12ssified
as sericite schist on tne basis of thin-s~(:ion analysis. The second majcr
unit is a large intrusive body (stock) c~ quartz-diorite. The body is
located on the south and west sides uf~dhon2j Lake. The lowey' portions of
the surface penstock and the powerhouse Sit2 dre underlain by
quartz-diorite bedrock.
The metasediments are part of tile Wrdilgell"-Rev,nrlgigedo metamorphic belt
that trends northwestward across kevil)agigedo Island. The bedding p1a~es
strike mainly north-northwestward and dip steeply westward.rhicknesses of
the individual beds, wherE-' measuY'ad, range from 1 to i8 irlches and perhaps
more elsewhere. Figure 8-4 presents stereographic ~lots of joint attitudes
that were measured during field reconnaissance. Jointing occurs at various
attitudes but the dominant set is parallel with the b~dding planes.
Secondary joints often strike northeastward and dip southeastward.
The rock is generally hard, unweather~d, and strong but tends to part along
preferred cleavages. Iron staini~g due to weathering of large pyrit2
crystals within the rock can be obsen'cd at outcrops. The metasedirrldlts
are intruded by granitic dikes and veins th~t 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 dior'ites. \4Jhere exposed at
outcrops, the rocks are F!n.Y'd and fresh. Petrnf]{'ophic ,}nalyses of bedrock
samples confirm the classification of the intrusive body as quartz
diorite. Because of its limited expos~re at the site, preferred jointing
or foliation in the rock has noL been identiFied at t~is time.
In qeneral, bedrock is eX00sed or cover~Q by thin, discontinuous surficial
deposits throughout the higher elevaticns near Upper Mahoney Lake. Ine
lowe)' dl'eas surrounding Mahoney Lake have both alluvium and talus that
reach substantial thicknesses.
Surficial deposits cbserved during the re(onnaiss~nce fa11 intu three
categories: 1) talus, ?) alluviur", and ?) oV0.lanche rjeposits. The
distribution of these deposits is shaw~ on the site geology map. Flgure 8-3.
b-5
, .
\
N '11 OM N
\
N 12 000
N 10 000
.!£fER. MAHONEY LAKE
" .~
I
:!
'"
" /
400 0 400 800 1200
~1----~~I--~~~A~l~E~\N~FE~ET~-=' ----~I
COOI0(11C units adapll.'d In pa."' ftom
131"-(1 <'Ind others uses Open File
:c.cpo,' 76 ~JA Top(\{ll'aplly taken
"0m map by R. W. Beck and As!>ociates I
~
Kg
~
•
LEGEND
CORRELATION OF MAP UNITS
Qal·Qts·Qavl Q1JATERNAR'r'
CRETACEOUS
MESOZOIC OR
Kg
MzPzs
Qal
Qts
Qavl
Kg
MzPzs
? •• __ .?.-
_ ....... -"---""""--
SL T ------
UPPER
PALEOZOIC
DESCRIPTION OF MAP UNITS
ALLUVIUM Strum deposits of und, silt and gravel.
TALUS. Rock .aste at the base of a cliff or coerle
debris m~lntling slope Herein inclu.i .... e of that
called '5(,'('e
AVALANCHE OEBRIS. Oep:l.it. of materi.JII1 .ffected
in lotal or in part by rapid slide. of l.rO! mane.
of snow or ice. -
METAMORPHOSEO BIOTITE -HORNBLENOE
GRANODIORITE Include. quartz diorite.
Frequently containing epidote. Texture and
composition ... ary depending on original rock type
and aftW)unt of metarno,.phic defo,.,utton.
METASEDIMENTARY ROCKS (Me.olOic 0" Uppe,.
PaleoJ:oic). D.,.k ~,.ay to sil""e,.y g,.ay phyllite
.nd flne-g,..ined Mffti-achist and schist. Pr-ob.lbly
~r-i""ed from inte,.b.:id.:i pelitic s.:iiment.ry ,.ocks
.nd from subo,.dln.te andesitic and basaltic .... olc.nic
and .... olc.nicl.stic rocks. Most commonly is a da,.k
g,.ay, fina--g,.ain.:i schist containing qua"!I, feldspa",
biotite, musco .... ite .nd pyr-ite. Unit is int,.ud.:i by
nUlfte,.ous g,..nitic dikes and sills.
SYMBOLS
Contact bet .... een units AFJpro)(imateiy iocated
Bed,.ock contaLl. inf{'"I'I'ed location.
Dolled .... he'·{'" concealed.Qu{'"ned where urKel·ta,n.
St,.ike and dlFJ of beddinq
or contact.
St,.ike and dip
of ,ointing
Strike "nd diFJ of fault or shea.-.
Se.smic I-efraction SUryey line
SITE GEOLOGY
---
N 12 DOD
N 10 000
H .~
""" IIiIiII
Figure:
RIVERS AND HARIIORS IN ALASKA
USArmyeorp. SOUTHEAST HYDROELECTRIC POWER INTERIM alEngI ......
,0,1.-District
B-3
5
Contoured lower hemisp here 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:
2-5% 5-10%
CJ 0:········ .. .. .. -. . .
~ ." '*-' ~ \:: : -• :~: ..
• • , ...... < ... STEREOGRAPHIC PLOT OF
15-20% PRIMARY JOINT ATTITUDES
III 11'1
iIIl\I'I!lIS AIIID HAIII __ III! "L .... a
UIa"""~ ~ .......... SOUTHCA$THYPROElECTMC POWWR INTI ..
_DiIlIrIct
'"",
FIGURE
8-4
Talus generally consists of angular, hard, and virtually unweathered
boulders of metasedimentary rock ranging fl"om 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.
Alluviu~ consists primarily of subrounde~ to angular fragments of
metased~mentary 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 mixtur'e of silt, sand, and gravel.
Several avalanche chutes are apparent in the t~ahoney 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, clastlc rock fragments.
Several faults and lineaments pass through th0 nroject site. Initial
observation indicates that the stream flowin~ from the upper lake is fault
controlled. Numerous north-south striking faults and fractures of various
magnitudes pass through the 2ast ridge. Two majOt' features stand Odt
because of their surface expressions. One fa~lt, Skyline fault, has a much
longer surface expression than other faults and crosses the projected
tunne 1 ali nement some 1, 000 fee"" h'om Upper Mahoney L.ake. One sei sni c
survey line crossed the lineament but rock of varying seismic veloc~ty was
not detected. The fault surface is exposed approximately 800 feet north of
the alinement and has a strike of N2SE and a dip of 85° NW. The other
fauH, Portal fault, crosses the tunnel west of the portal and !las 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° SEa The
tunnel ~'JOL!ld pass under the trench to prevent avalanche damage to tile
penstock. There is no indication of recent movement along these faJlts and
no seismic events are recorded anywhpre for the area. The amount and
direction of offset on the faults are indeterminate. The geologic section
through the tunnel and penstock alinement, Figure 8-5, snows 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 s~te since 1899. There have been two earthquakes of
maynitude 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 s1te. Earthquake epicenter's in the \~egion are shown G'I the earthquake
epicenter map of ~igure B-1. Most of the earthquakes appear to ~e
3-8
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 earthqudke 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
magnitude 5.0 have been generated by movement on it, but judging
length, it is capable of producing earthquakes of magnitude 8.0.
Chatham Strait fault is 125 miles northwest of the Mahoney Lakes.
of
by its
The
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 epicentet, and the
geoiogy 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 genel'ated 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.
8-9
AIR VENT
-~1500
::::E
Q)
> 0 ..c c -Q)
Q)
lL. -z 1000
1
0
~ > UJ
...J
UJ PORTAL Elev.6831
500 PENSTOCK
ERHOUSE
0~----'----~--------~--------~---------+---------+---------4---------4--------~~--------r---~----+---~~~~~--~~~~~~~~~~~~~--
o 500 1000 1500
Colluvium. Talus and
slope debris (scree).
2000 2500 3000 3500 4000
DISTANCE (FEET)
./ Fault. Apparent dip
/" ? projected from nearby
/' exposures.
Schist. Apparent dip
projected from surface
/'
?
/' . /'
/'
/' Geologic contact,
approximate; queried
~1IIIiiIIl'lilillll.'IiIIIIJI."", exposures. /' where uncertain.
REFERENCE: Topography faken from map by R. W. Beck and. Associates, certain
facility location information from Corps of Engineers (Inv. No. DACW85)
o
GEOLOGIC SECTION THROUGH TUNNEL &
PENSTOCK ALIGNMENT
..,...
IiiIiiI Rive .. AMI HARIIOIIS III ALASKA ::::c:-r SOUTHEAST HYDROELECTRIC POWER INTERI.
_1lIoIricI
FIGURE
8-5
OJ
I
Tab 1 e B-1
Maximum Peak Bedrock Accelerations at the Mahoney Lakes
Maximum Historical Maximum Credible Di stance Maximum Credible
Length Earthquake EarthquakeI/ to Site Bedrock Accelerationl/
Fault (miles) Magn it udell Magn i tude.].l (miles) (% of gravitl:)
Fairweather
(offshore segment) 300 8.6 8.6 160 5
Queen Charlotte Island 350 8. 1 8.6 110 5
Ch ath am Strait 200 5.0 8.25 125 5
.lI 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.
=========--="===,'='-=' ====================
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
MODiFiED -MEFICALLI lNTENSlTV SCALE OF 1':)31
Not felt by people, except under especially favorable circumstilnce~. However, dizziness or nausea may be experienced.
SometImes birds and animals are uneasy or disturbed. ~irees, ~tructures, I,quids, bodies of water may sway gently, and
doors may swing very slowly.
Felt indoors by a few people. especially on upper noors of muhi-stmy builoings, and by sensitive or nervous persons.
As in Grade I. birds and animah are disturbed, and trees, stru<::urcs, liljulds and hodies of water may sway Hanging
obJccts SWing, cspecially If they arc delicaiely susP"ihled.
;'elt indoors by several people, usually as a rapid vibration that may noi be re~ognizl'<l a.s an earthquake Jt·i'irst. VibratiQr, is SImilar
til th.at of a light, (lr lightly loaded trucks, or heavy HUCks sonIc JIS!2ilC~ aw~y. Durat,onmay be estim.ated in some cases.
Movcllle,lts may be appreciablc on upper levels of tali Stfl:cturc;. Sta;l(~!ng li!O(OI cars may rock shghily.
Felt indoors by many, outdoors by few_ Awakens a f·~w individl.~'s. \l2;t\(,[J,~fiy light sleepers, but frightens no onc e',(ept those
~pprehensive from previous experience. Vibration like that due to ;>~>"ing 01 Leavy. or heavily loaded trucks. Sensation like a heavy
body striking building,or the falling of heavy obje<:ts inside.
Oishes, windows and doors rattle; glassware and L10ckery diflk ,"r,d ch'h Wdh and house frames creak, es"cclaliy' If
intensity IS in the upper rangc of this grade. ibngrng object; '.,flU'! ,Win],. Liquids in open ve,sels arc l11\turbc.J sl'ghtly.
Stationary ,.utomobiles rock noticeable
Felt indoors by practically everyone, outdoors oy most people. Di,'ection ('~n ufter be estimal<:d by those ol>!doors. A.wake,ls
many, or most sleepers_ Frightens a few people, with slight excitemen:: some PU50IlS r:J~' outdoors.
Ihllldlngs tremble throughout, Oishes ~nd glassware break to SOIl1-: e.\t'T,t. \,;.nuvws crack in some lascs, Gt.t ;,ot genl'r-
ally. Vases and small or unstable objcL'ts overturn I;' man:, !mi.:.nll". dnd a few fdll. Hangmg objeds and doors ,wing
generally or considerable. Pictu'res knock agaimt wab, or 'WiD;: out 01 ;)I.,<:e. Coors and shutters open or close abruptly
Pendulum docks stop, or run fast 8r sl()w. Small ob,l'l'ts Il1C>V,." anJ f",,:shings may shift to a siJght c';tcnt. SmaL
aIllGunh of liquids spill froIll well-fiilcd open conta;rv! ,. Trecs a:,d hUS;,LS sh"kc sllght!y,
Felt by everyone, indoors and outdoors. Awakens all sleepers_ Fri~lell' r.~any people; genela! ex~itement, and wm\! persons
ru n ou tdoors.
Persvns movc unsteadIly. Trees and bu:;hes sbke slightlY IG moderatcly L:qu'ds ;:fC set In strong mr)'ivn. S:na!l bells
In churches and schools ring. Poody bl.!ilt bLiildlngs rrny be damagr.d. Piaster fall,' in ~mall amou'lls. Otner plaster
L'r<lcks somewhat. Many dishes ar.d glassc~. and a t~", "'ndo'.l's, hr ... ~;~. Knilk-KnacKs, books and picttJ"~' fall. Furniture
overturns in many instanccs, Heavy furmsillngs rnnvc
Frightens everyone. General alarm, and everyone rum Guldo'):s.
Peopi ... find it difficult to stand. Persons d;i,'c.g:ars rotlce sil"king. Trees ~.nd blhh, , ,h~kc rTJodcr"tely to strongi)
Waves form on ponds, iakes and stream,,, Water is n;uadier!. (;f'~'iC: or sana ',tream b:mk, C!vC in. Lugc c'hurcil bel! ..
rrng. Suspended objects quiver. Damage IS neglJgib!e rn buildlng'-cd good des!gr. Jnd ,,,nstrul(ion; silght tu modl·r"~ ...
rn well-bUilt ordinary buildings. conside:abic. in pooc;y built or badlv deSigned o'jlidlng' J;~obc h<;uscs. old wall<, ;cspeCl-
ally where laid up without mort,,, J. spirl's, e~c. Plaster and SOlll,.) S)llCl'O Ldl \iany WIlj(;')W~ and SOilll' furniture bleak
Loosened brickwork and tiles ,h:lkc down. WCJk chImneys break at the [oo!lim. ('"rnilT". fa!! fror;; towCf, ~nd high
buildings. Bricks and stones are disloGgcd. Heavy furniture overturns. Con':rete IrrigatlOl1 ditches HC cocl\idelably
dalllaged.
General fright, and alarm approaches panic.
Persons driving cars arc di~turbed. Tree~ shake 'trDngly. and branches and trunks break off (especially palm trees). Sand
and mud erupts in slllall amounts. (-'iow or springs and wells is tempc[drily and sometimes perl11af'~ntly changcd. Dry
wells renew !low. Tenlperatures of spring and well waters vanes. Dall1~gt' slight in brl<'k ~truc'tures bUI!t cspcLlaliy 10
withstand earthquakes; l'onslderable in orJinary suhtar.t1a: buildings. WIth some partJalcGUapse; hcavy.in SO"l~ wooden
houses. with sOllle tumbling d0wn. Panel walls break av'ay in fral1ll' structures. OeL'ayed piling, break otf. Wails fa:1
Svlid stone walls crack and break seriously. Wet glound" and ,teep slopes ~rack to some extc-nt. Chll11ne:.".~olllll1n·'.
IllonUlllents and fadory stacks and towers twis, :md fali. V~rv hc,,":; rurrlHurc moves consp;l'llOl~sly or uw' turrl,.
Panic is general_
Ground nOlck, complluous!y. Damage .' "(Jnsill~rabk If) masonry stroJdurc, built '!spcl'Ially to withstand earthquakes.
great in other masonry buildings -SO"IC c:)l!apc in large part. SOllle wood rralll'~ houses built espeCIally to w!t!1stand
earthquakes arc thrown out of plumb, other'. arc shifted \S :1OlIy off foundati')ns. Reservoirs :ue ss!riousf~.' d;"llaged ano
undcrground pipcs sometimes break.
Panic is general_
Cround. especially when loo';c and Wet. cracks up to widlhs ell' scvnallflchcs; fISSUL'S ,ip to" yard in Width Ill" paralicl
to canal and stream banks. Landsljding IS cOJlsldclable fWIll river banb ~nd steq) c"Jash. S:md and mud shifts horizon-
tally on beaches and tlat land, Water level changcs in we!!s. Wate. is thro",n un bar,ks of canah. Iakc,. rllcrs. etc. Darns.
dikes, embankments arc seriously damag<'d. Wdl-buii: w~)o(kll .,(rultures a:1d bridges arc scwrcly dartlaged, and;omc
collapse. Oangcr(;u; cracks develop Ir, C',\'dkn: bride walls .. "lost i1;~SOi1rY a"j frame structure'. and· thea i'o:lndatlc'ns,
arc destroyed. Railroad rails bend slig:rlt1y. Pi".: tincs buried i~ :~rth tcar :,,)Jrt or arc lfllShcd endwise. Operl nad;, and
broad wavy folds open in cerncn' p"vemenls and asphalt rOad S[l,Lli··.'.S.
Panic is general,
l!isturbanu!s In ground arc m.my and widespread, varYing with (he grour.d matccial. Hroad fissllrcs. earth sl,,:n,'s, "nd
land slips develop in soft, wet ground. ·W.ter charged with 'ar,d and lTlud is cjcl·ted in largc amounts. Sea waVl'\ "r s;;:,',
ficant magnltudc may devclop. lJan~agc IS scwrc to wood frame s(r"Llmes, cspe .. nliy n'~ar ,hock centcr" grear. to ct,,,';s,
dikes and embarkments, even at 10'1[: distam'es. I.·('w it "ny ,naso'lry SlructUfCS rel11aln standing. Supporting >,Icrs or
piilars of large, well-huilt bridges :He wrecked. Wooden ~r,jges thaI. "gIVe" ,;:c less affccted, RailroJd rails h,'l.d gr\'~dy
and sOllle thrust endwise. Pipc Imes l:'llri,'d in eart:l arc put c\'lll,ltCtdy out of scrVllT.
Panic is general.
Damage is total, and pradically all works ot CUnslIUdlOfl ,'rc dJr;l;,g",j glcatly \'r destroyed. DiS'L.lb"."c'l'S In t:ll' ground
arc great and varied, and numerous shcaflng c;acb develop. LandsLdn. l'OL'k (;!Is, and slumps in rivcr banks arc nUl1H'r-
\Jus and extenSive, Large rock m<l>ses arc wrnched IU0se and torn off. l:ault '~IPS develop in flm; wck. and horizontal
and vcrtKal offset displacements are notable. Wdter ;'hannels, buth su,fa,e :;nu underground. arc disturbed and modifIed
greatly. Lakes 'ICC dammed. l:ew waterhi!s Jrc prlldul'"d. rivers a,e df'fkcr',d, etl' Surfa,'c W:j\CS are ,~en on grol2~c! sur-
faces. Lines of sight and level are distmte'.'. Objects are throy.,n ,;,:; ..... :,rd mt') ·.he air
MODIFIED MERCALLI INTENSITY
PREVIOUS INVESTIGATIONS
Numerous reports on potential hydro~ower sitesf6r 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 Hydroelectr'ic
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
[Jams i te .
Thedarnsite would be located near the outlet of Upper Mahoney Lake. This
valley is V-shaped with relatively steep sides and virtually no flat drea
in the streambed. Bare rock is exposerl on the cast 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 stabl.e 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 binwal1
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. Seconddry 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 wer~ 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
8-13
of the river. One joint set has been rotated approximately 30° compared to
the other set. The river down~tream 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 in a stretch of the river that has a uniform gradient.
The joint set rotatlon, the. river offset, and waterfall suggest pivitol
rotation of the geclogicunitsat the damsite on one side of the river
compared to the other. The i~dividual 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 ne
open at depth. Aerial photography and slickensided primary joint surfaces
suggest a fault/shear zone trending N30E and dipping I/est .. This is the
attitude of the primary bedding plane jointing. The rctatiJn of the
geologic units on one side of the river compared to tl:e other also indicates
faulting. This possible fault and the Skyline fault intersect near the
waterfall and river offset.
The metasedimentary bedrock is hard and exc~vatlons wa~ld 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 lead to block-glide
failure of rock parallel to the existing slope. Once the dam were
constructed, the rock spalling 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 alluvium 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 pyritizatonhas
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 be~eath the ground
surface. N8 adverse joints or fractures could te 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 slope
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.
3-14
The multipipe scheme has been studied to the extent that it appears
feasible. The Alaska District queried contractots and Waterways Experiment
Station personnel about the feasibility and desirability of such a 5cheme.
Danger from slab rocks sliding down and closing off the intake area is
virtually nonexistent with this scheme and the fractures near the lake
become less important. By using several pipes to penetrate into the lake,
loose slJbsof rock would be stabilized by the pipes p~sstng through the
slab. Studies and explorations of the tap area will be ~adeto 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 iDtake angle. Fractures and joints passing through
the valve chamber of the mult i pi pe scheme ar'e of more concern than those
near the lake, but possibly, the g~outing 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
8-5. 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 tunne-i 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
Porta 1
The steep slope of the tunnel would place. the outlet portal location at
elevation 396 at the bas~ 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 secJndary joints attitudes at the po~tal site. The
east-west strikin~ joint with a vertical dip is the only joint that is
probably open at depth that would result in we~ge failure.
West of the portal site'is the Portal fau~t, 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 SOU-foot depth.
Future exploration should determine the Drox~mity of the Portal fault to
the portal opening. As projected on Figure 8-5, ;t passes within 300 feet
of the portal at tunnel depth.
Surface Penstock
The penstock would be constructed on the surface between the tunnel outlet
portal and the powerhouse. The area is underlain by talus and avalanche
debris, which contains rocks up to 20 feet in dia~eter. 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 convent~onal equipment unless large
blocks of rock were first broken by blas~in9. The bedrock beneath the
talus would provide suitable foundation support for the penstock.
PO\'Jerhouse
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 i1termittert tributary
stream channel and is 5 to 10 feet above flood stage for the stream
channel. The alternate powerhouse site can be r0ached by walking
approximate1y 1,500 feet upriver from lower Mahoney Lake. This site is
adjacent to the river and in the flood WJy.
Local geology at the powerhouse and a1trrnate powerhouse sites consists of
blocky unsorted alluvial and colluvial deoosits primarlly composed of
avalanche talus debris. The debris overlies granitiC and metasedimentary
basement bedrock. A seismic refraction surJey 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 unsorteo talus-avalancne debris
ranges from gravel to 20-foot bould~rs. Boulders and blocky talus form 50
to 75 percent of tne unconso1idated deposits.
3-](1
By building the powerhouse into the toe of the hill, 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 metasedimenta~y rock
consists of carbonaceous quartz sericite schist. The schist was derived
through low to medium grade contact metamorphism of geosyniclinal
sediments. The granodiorite intru~es, overlies) and postdat~s the schist
beneath the powerhouse site. Contact r2lationships bet.../een the schist and
granodiorite are concealed andinf~rredfrom surficial dep&sit distribution.
Primary bedding within the schist strikes northeast-southwest and dips
steeply to the west. The jointing foll·ows relict bedding. No aerial
1 ineamentsdue to fauH i ng were observed near the sites.
The alluvial deposits at the alternilt"e site ma,), be unstable in the event of
an earthquake. The dynamic response of the foundation materials should be
studied in more detail, s6 that the alternative site can be considered
further.
MATERIAL SOURCES
Exploration for construction materials, particularly for concrete
aggregates, has been a part bf all investigations for the Mahoney Lake
hydroelectric project to date. Although only mOderate quantities dr'e
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 test:;
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.
~ams He Quarry
An extensive talus deposit ·is located imrnediatE'ly adj(Y:ent to the ll.~ft
abutment of the proposed structure. laboratory tests and microscopic
(petrographic) examination of this material sf!:J;"/ it to be accep1:<1ble for
concrete aggregate, rockfill, or r'iprap of limited sizes. See Appendix 13-2
for these data. Extensive processing of this material would be required
for concrete aggregates. Access to this source would be via helicopter.
In general, it appears that the bulk of any or all 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.
D-U
There are no local sources of cement or pozzolan, so 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, temp~rature studies, freeze/thaw tests, and exact
quantity surveys of any source selected.
o i sposa 1 Sites
Sufficient sites would be available for disposal of tunnel wastes. Areas
close to the tunnel portal would be suitable if environme~tal constraints
were met.
CONCLUSION
In conclusion, the project appears feasible based on the information
available~ The engin~ering characteristics of the bedrock should be
assessed and additional explorations will be required. Future
investigations should include dril-ling 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
A~PENDIX 8-1
FOUNDATIONS AND MATERIALS
Tests on Gravel from the Powerhouse Stream
NPDE[~-uS-L (82-C-118 ) 19 Jan 82
MAHONEY LAKE HYDRO
heport of tests on Gravel from The Poyer House S~r~~m, Alaska
1. qQope: un 9 ~ov 81, 1290 Ibs 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. Analysls of
the bulk gradation indicated the f~llowing:
(1) 1 1/2" MSA could be produced,(2) the natural aggrel1.:at,e t~ontained a
signlficent quanity (201) of flat particleF, (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 pif;0'~D, and
(4) rodmill sand would be required. Aggregate quality tests were made
on the ndtural material.
followlng completion of the bulk gradation and aggregate quality tests a
processing scheme was devised to producei 1/2" MSA blended crushed and
natur::d aggregate. Due to the celatively small size of the sample, the
laboratory processing study may not be representative of full ~cale
processing efforts. Detailed results are as follows:
NPDEN-GS-L (82-C-ll8)
SUBJECT: Mahoney Lake Hydro
2. Bulk Gradation:
6"-3" 3"-1~" ---a. Weight, lbs 216 385
b. Percent, % 16.8 29.8
c. GrJdation-Percent Passing
s-inch 100
4-inch
3-inch a 100
2 1/2-inch 82
2-inch 48
1 1/2-inch 12
I-inch 1
3/4-inch a
l/2-inch
3/8-inch
No. 4
No. 13
No. 16
No. 30
No. 50
No. 100
F.M.
3. Aggregate~ality Tests (Natural Gravel)
Specific Gravity, BSSD
Absorption, %
Los Angeles Abrasion
% loss'@ 100 rev
% loss @ 500 rev
Soundnt.'ss of Coarse Aggregate
by Accelerated Freezing and
T!l3~iI~R _____ . ________ . ____________ .
% loss by weight @ 300
Lye les
F.l-~'!:_ .3!1~_.r:.l.O:lg~_c~1 _P.0T~_~c1-_~~
% Flat by weight
'{ Elongated by weight
i "t .1 I, '(
0.7
16.2
100
98
50
10
1
]
1.1
2.2
20.0
1.0
2Yon
5.2
22.5
19 Jan 132
19.5
100
97
59
35
2
2.1
14.0
0.0
14.0
Fines
228
17.7
100
98
77
55
32
14
7
3.17
2.1
Tota]
1290
100.0
100
83
78
68
<:, -;
JJ
46
38
29
25
18
14
10
6
2
NPDEN-CS-l. (H2-C-11R)
SUB.I EC'I: Mahoney Lake Hydro
*
a. Bulk ~radation
Lhs
Percent
Stockpile
216
17.7
]16**
25.9
J 9 Jan H2
252*
.20.6
'*'* 69 Ibs of 3"-1\/' material sampled for petrographic examination.
b. t'E ima!LSrutih !:,!1£:
1 ) Crusher: 18x24 inch jaw at 2 15/16 inch setting
2) Feed: lhs 216 316
3) Produc:l :
Lbs 83 351 68 23
Percent· 15.6 66.D 12.8 4.3
c. Secondary Crushing :.
1 ) Crusher: 18x24 inch jaw at 1 15/16 inch set Ling
2) Feed: 1bs 83 151
J) I'rnduct::
Lbs 250 119* 47
Percent 57.7 27.5 10.9
'* Stockpile 1 19 Ibs.
d. Le.sna r L_S:_~ush i!.I£:
1 ) Crusher: 18 inch Gyratory at 3/4" MSA setting
2) Feed: lbs
Primary 68
Secondary 250
3) ProJuct:
Lbs 64 185*
Percent 21.4 61.9
* SLuckpile 165 Ibs.
t:. l\nJrn i 11 Sand: --,---~-----------_.
I ) RodrnilL: 18 inch 0 x 42 inch Drum
2) Feed: Ibs
I'r imary 23
Secondarv 47
rernary 64 20
l ) I'rllollct:
J.hs
.j ) t.n~)s : 1he;
Perl <-'ilL
" ~>l.,h,ll" I lqJ I t1 "
2Ld*
IK.7
7
1.3
17
3.9
50
16.7
7
1 7
SO
16CP',
hb
L9.3
1221
100.n
532
5)2
100,Cl
4'34
433
100.0
318
299
100.0
228
]6()
NPDEN-GS-L (82-C-118) 19 Jan 82
SUBJECT: Mahoney Lake Hydro
f. Product:
1) Lbs
Natural 209 252 228 689
. Crushed 119 185 160 464
Total 328 437 388 1153
2) Percent
Crushed, each nominal size 36.3 42.3 41.2 40.2
Each.nominal size 28.4 37.9 33.7 100.0
3) Total Processing Loss, Percent 5.6
g. Gradation: Combined Crushed and Natural Gravel
Nominal Size
IY'-3l4" -----3/4"-No. 4 Sand
% % % Alt. No. J
Size Pass Specs Pass ~ecs Pass Specs
-------~------------
2-irich 100 100
1!.-2-inch 94 90-100
I-inch 44 20-45 100 100
3/4-1nch 10 0-10 98 90-100
1/2-inch 1 62
3/8-inch 1 0-5 34 20-45 100 100
No. 4 3 0-5 98 95-100
No. 8 82 80-95
No. 16 62 55-75
No. 30 39 30-60'
No. 50 19 12-30
No. 100 8 2-10
F . ~1. 2.92 2.40-3.10
NPDL 1794
.' ,
i i .'
;,i,. i'" II j I' :: I';
i' ~ I' I' I
• I 'IIi I'll) •
I,:
,J
Ii I i r, 1 I
I :,
, !:
, i
Paul D. Hecht
I,H)I':I, ; 1i<\11 I·: ii'
I ",j I " I :,
! !:
I:
, ,
"
, I '.
Ii:
• I ..
;.'.1I1~U:' The aggrel:Jte was Cl)IIlPUSl.'J of generally haru sound materL,d. The principle roc;~
yp,-" was a fine grained quartz-muscovite schi.st \.,rhich was foliated. This prodilced an
it;grcgate which was gcnerally fLit to elongate in shape with 9% of the coarse aggn'gate
leeting the CRD 3 to 1 ratio of a flat particle. Much of the material showed secondary
',illeralization with numerOliS vvins of pyrite present in both the schist and t112 quartzite.
IVl.'rage percent composition of the eoan.,e aggreg,lte was 91 ~;chisl ,mel <) qU<.lrtzitc. Percent
,.ind compositi(ln \ ... .l~; 61 scldFt, 11 quartzite, 16 quartz, 4 muscovite. 2 llOrnblende, 2 pyritc.'.
magnetite and 1. g3nll.'t.
Pc rcen~.~~ve Size
:ock 6. Hi ncrals 1 In'' 3/4" 1/2" No.4 No.8 No.16 No.30 No.50 No.lOO Pan .. ------------------
Schbt 96 93 89 85 84 82 80 65 39 18
~uartzite 4 7 11 15 16 16 15 13 10 7
\.,~UJ rtz ? 5 17 29 42
~;u~LoviLe 3 (, 14
t!ombldlde 1 5
l'yrill.' 1 4
1
5
~------~r---------r---~----r---r-----r-----~~r-~~--~r-------~~-
." . .j..
t.P. Ot~-
z
I.l.i
U
((
w
0..
!f).0~~·~---~~~----~~-+--------~r-------~+---------~--------~---------+~
<..')
Z
~
~ ... u
~1.0t~ ~. _
~ I" -~ -.... -----:=
_.1 /~_ .-
o~ -
....• -
'j
-D.O~---~~~0---------~~--------~---------~----------~--------~--------~--3~65
SPECIMEN
SE ~ N(,
1794
17Sl.
AGE. DAYS
S."MBOL COMBINATION
• Higb Alkali Cement MAHONEY LAKE HYDRO
DISTRICT aska
• Low Alkali Cement AGGREGATE l -Pit run natural sand from
_____ .---'--------------------1 I-__ p_o_'t'_r~_f"_. _H_O_u_8_e __ S_t_r __ e_a-:-m_,_A_l_a_s_k_a_. ______ ~
H'-GH ALKALI crMf N r 1 01 ;'< Na ,':} ",[MARK::.
Whitehall Cem(>nt Co.,
Whitehall, PA
L')W· ",Lf'ALI (f_MU,1 O.48·~rj.J:U fl-'
Blend o~ Oregon, Idaho, and Lehigh •.
T e T & II Cements f
Plutted J . H • w/c.1 ~J'J.
82-C-118
JAMES K. HINDS
(Da I f' ", Pt'p,., I I Chi.,!'. Cc'''''C'-~'~ b"~'>(r
REACTiVITY OF AGGREGATES WITH A!.KALIES IN PORTLAt'JD CEMENT r-.Jr·'Q FORM':<6;:;
JUL'f49 -'...) (MORTAR BAR METHOD) tl.1ETHOD CRD"L-12J
CORPS OF' ENGINE.ERS NORTH PACIFIC DIVISIGN 'rESTI~-JG I.AI1:.r<ATCC;'Y ---_._----'---------'
r-ir, ----~---~r-------,------r--------.-~~.--~--=----------~~-------.------,
1
I t --~~~~+-~~~~-+---rl
r-~---r~~~~+-~--~~----~------+------+-----~I-J ·1 I
I ;
I :
I t.o·O ( ..
'7
L "
W .'
U
cr:
"J
[,
-.--~---+--.----.---+-~----! -i
I ===-f' II ~ ____ -+.,--___ -+-___ -+I_ •. · . ._ 1 I
/ / I I 1 ;0. ()·~--.-'''';''''4./-+-:''''-----'-· .7 ...... 1""+---:------+---_---+-----'I' I I '
C,I .--1..----.----+------! I i/.~· -.. .-i ----1------1 j -1
o r-'----+--I--+----I-I-----+------I· --l---'--'-H
I I I " .1. ~·----·i·-~---+----------.---r----------.----. -. I '--'-I---j
lP· () !f-'
;. ..... Vl LLI.. y' ~
I _O.ll~---n---_:;_n--~ .. -J .nL IJ
~l \-1 L: r J:( r' '-l,' .(' t PI r,' .,',,!., ·;1\(., ,I-I".' r ====.-J F-i , ' ... ~.~f__----~::~~~~~~-
• Higli I\lkilli CCnlenl
1794 • Low Alkali Cement
I'" :, J I " I
MI\IIONI,:Y I,I\KI': IIYI)IW
---------.. -.----1
r'.-·'-' ,_'_1_, i_' _I _._ ... -' ~\l{!J_i.· k_-~-~ ________________ . __ .. ____ 1
Pit rW1.natural sand from
,
I Powerbouse Stream, Alaska. I
I . ---------------1
APPENDIX 0-2
FOUNDATIONS AND MATERIALS
Tests on Damsite Quarry Stone
NPDC;~":'GS-L (82-C..;.118 ) 25 February 1982
MAHONEY LAKE HYDRO
,Report of Tests on Damsite Quarry Stone
1.~i&..: On 09 Nov 81, 1018 Ibs of pit run quarry stone composed of twenty
sack samples were submitted toNPD Lab for bulk grada.tion, rock mechanic
tests, proce~si~g studies, and aggrega~e quality tests. The sample was
generally flat an~slab ~haped with a h~avily 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 thatrodruill sand would
be required. Following completion of the bulk gradation, approximately 113
Ibs of the larger pieces of stone were removed for rock mechanic tests. A
processing scheme was devised to produce 3" MSA. Due to the flat angular
structure of the rock, recycling of the crusher product was required to
produce the 1 1/2u-3/4" size. Due to the relatively small size of the sample,
the laboratory processing study may not be representative of full scale
processirig efforts. Detailed results are as shown in Table I.
3.Tne larger siz~ stones for the rock mechanics tests were cast in concrete
prior to coring. Cores were drilled both normal and perp~ndicular to the
plane of foliation. NX cores were drilled where possible; however, due to the
:small size of the stone most tests were ~ade on 1 1/4" diameter specimens.
Re~overy of cores drilledparellel and perpendicular to the foliation plane
averaged 86 percent and 38 percent, respectively. Tests included splitting,
tensile and compressive strength, ~odulus of elasticity and Poissons ratio.
Where possible, four to five specimens were scheduled for each test. Detailed
results ,are showp in Table II.
NPDEK-GS-L (8~-C-118) 02 l'1ar 82
MAHONEY LAKE HYDRO DAMS ITE
TABLE !
Report of Processing Studies and Aggregate Quality Tests on Quarry Stone
J. Bulk Gradation:
a.
b.
c.
2.
a.
*
weight, lbs
Percent, %
Gradation-Percent Passin,&
9-inch
6-inch
5-inch
4-inch
3-inch
2',-inch
2-inch
I',-inch
I-inch
.!70cessing:
.!7 imar_v Crushi~
9"-3"
Nominal Size ---~ --j">::·-I l! 2'-o";-'----T-o-t-a-l--
847
78.6
100
91
47
30
0
--231---1078
21.4 100.0
lOa
29
II
5
3
100
93
58
45
21
6
2
~1) Crusher: 18x24-inch jaw at 2 15!16-inch setting
(2) Feed: 898 lbs Pit Run 9" MSA
(3) Product
(a) Ibs
(b) Percent
Stockpile: 250 lbs
Plus 3"
265
29.7
3~~.I~i~-
452*
50.7
Nominal Size
1';'-3/4 1, 3!4"-N0. 4
-'108------(;5---
12.1 5~1
'b. Secondarv Crushi!l.£
(I)
(2)
(3)
Crusher:
Feed: Ibs
Product*
lSx24-inch jaw at I 15/16-inch setting
265 202
(a) Ibs 2 155 209** 74
(b) Percent 0.4 33.2 44.8 15.8
* DOe to flat particle shape the plusl':z-inch material from the initial
recycled through the jaw crosher. Results are for the two passes.
** Stockpi Ie: 180 lbs
(1) C,usher: 18-illch Gy,'otory at 3/4" MSA setting
(2) Feed: lbs
(3) Primary
(b) Secondary
(3) Prnduct:
(a) lbs
(b) Percent
* Stockpile: 166 Ibs
d. R,·dmi 11 Sind
(1) Rodmill: IS-inch
(2) Feed: lbs
(:3) Primary
(h; Se;:::mda,y
(c) Ternary
(3) Product:
(a) lbs
(b) Percent
(4) L,)ss:
(a) Ibs
(b) Percent
108
2 1.';5 29
78
26.5
0x42-inch Drum
7S
160*
56.5
45
7~
? ' ~.4
Total
B91
100.0
467
27 467
5.8 101).C
cru.shln~ was
29:.
5.0 29~
17.0 100.0
?l
~~
~ ,
50 295
203 203
100.0 100.0
92
31.2
NPDEN-GS-L (82-C-118)
SUBJECT: Mahoney Lake Hydro
02 Mar 82
Nominal Size
Plus 3" 3"-1~" 1~"-3/4" 3/4"-r\o. 4 Fines Total
e. Product ---
(l) Ibs
(2) Percent
(3) Total Processing Loss. Percent
250
31. 3
180
22.5
3. Aggregate Tests-Processed Quarry Stone:
G. Gradation
Size
b.
4-inch
3-incl.
2l2-inch
2-inch
ll:,-inch
I-inch
3/4-inch
l/2-inch
3/8-inch
No. 4
No. B
No. 16
No. 30
No. 50
No. 100
F.M.
Specific Gravity.
c. Absorption. %
BSSn
d. Los Angeles Abrasion
% loss @ 100 rev.
% loss @ 500 rev.
3"-1~"
%
Pass Specs
100 100
98 90-100
68
37 20-55
8 0-10
2 0-5
2.74
0.5
e. Flat £. Elongated Particles
% Flat by weight 33.0
i. Elongated by weight 2.0
Total 35.0
f. Soundness of Coarse
Aggregate by Accelerated
Freeze-Thaw
% loss by weight @ 300
cycles
(2)
Nominal
1~"-3/4"
%
Pass Specs
100 100
90 90-100
28 20-45
6 0-10
2
1 0-5
2.74
0.7
3.6
16.1
9.0
1.0
10.0
0.4
166
20.8
Size
3/4"-No. 4
%
Pass Spe('~
100
97
62
33
4
100
90-100
20-45
0-5
2.73
1.0
7.0
0.0
7.()
203
25.4
799
100.0
10.3
Sand
% Alt. Nvl
!'ass ~
100
96
81
62
41
20
7
2.93
100
95-100
80-95
55-75
30-60
12-30
2-10
2.40-3.10
2.73
1.1
NPDEN-GS-L (82-C-1 HI) 25 Feb 82
MAHONEY LAKE HYDRO DAMSITE
TABLE II
Summary of tests on Cores Drilled from DamsiteQuarry Slone
1/ .
Tests -.-.--.----c----2~
Cores Drill~d Normal to Cleaverage Plane -
Splitting
Strength; Tensile Compressi"e Modulus of Poisson's
Core (Brazilian) Strength, Strength, Elas£~city, Ratio
No. £!!..i P~.-·--. Ei ____ Exl0 psi _ !!------------
A-I 1895* 47,810* 9.19 0.161
A-2 37.75* 25,900 7.83 0.162
A-3 580
11-4 3A60
B-1 2345 26,700 7.43 0.163
B-2 1625 19,640
B-3 i050 1155
F-l. 480
G-l 2610
G-2 2745
.1-1 285 61,500 8.79 0.l44
J-Z 65
K-J 2255
K-2 3225 ".
Q-1 360
Average 2625 490 36,310 8.31 0.158
High 4895 1155 61,500 9.19 0.163
Lo,", 480 65 19,640 7.43 0.144
Std. Dev, 1290 415 17,640 0.82 0.009
C-1 1905 '}j
C-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 O .. 326
D-3 1210 980
E-l 3955* 1475
E-2 3305* 1620
£-3 35,170 10.38 O. J39
H-1 610
0--1 241)5
S-1 1:::95
S-2 1430
--.--
Average 2125 !L8S 24,590 11.22 0.254
High 3955 .1745 35,33') 12.62 0.326
LC'w 1120 610 11,050 10.22 0.189
Std. Dev. 1135 475 12,010 1.20 0.068
NPDEN-GS-L (82-C-118) 2S Feb 82
TABLE II
MAHONEY LAKE HYDRO-Summary of Tests on Cores Drilled from Damsite Quarry Stone
NOTES: 1/ Laboratory Test Methods:
a. RTH 113-.BO,"StandardMethod of Test for Determining the Splitting
Strength Of Rock" (Brazilian Method)
b. RTH.1l2-BO, "Direct Tensile Strength of Intact Rock Core Specimans"
(ASrM D2936:"7B)
c. RTHlli-BO, "Unconfined Compressive Strength of Intact Rock Core
Specimans" (ASTMD2936-7B) .
d. RT1l201-BO, "Elastic Moduli of Rock Core Specimans in Uniaxial
Compression" (ASTM D3148-79)
2/ All tests on nominal l!z;-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)
NPDEt\-GS-L· (82-C-118) 02 'br 82
MNIONEY LAKE H)1)RO DA.'1S I TE
TABLE·l
Report oC Processing Studies and Aggregate Quality Tests on Quarry Stone
I. Bulk Gradat ion:
Nom inal Size
a. Weight, lbs
b .. Percent, %
9"-3" -3'ClT/-2-"--Lotal'
847 -i31--1078
78.6 .21.4 100.0
. c. Gradation-Percent Pass~
9;"inch
6-:-inch
5-inch
4-inch
'3-inch
2'0-inch.
2-inch
·l'.-inch·
I-inch.
2. Processing:
a. .!:.:ri~_;]ry . Crushin£
100
91
47
30
o 100
29
II
5
3
(I) Crusher: 18x24-inch jaw at 2 I5/16-inch settin~
(2) Feed: 898 Ibs Pit Run 9" MSA
100
93
58
45
21
6
2
I
t\ominal Size
*
(3) Product
(a) 1 bs
(b) Percent
Stockpile: 250 Ibs
plus 3" ------265
29.7
3 II_II "-
452*
50.7
~~-'~}!!~~
108
12. I
(I) Crusher: I8x24-inch jaw at I 15/16-inch setting.
(2) Feed: Ibs 265 202
(3) Product*
3/4"'·1"0. 4 ---_ .•. -----
45
5. I
(a) Ibs 2 155 209** 74
(b) Percent 0.4]~ ~ 44~8 15.8
* Due to flat particle shape the plus I',-inch malerL11 fro", the initial
recycledthrnugh the jaw crusher. Results are for the two passes.
** Stockpi Ie: 180 lbs.
(l) Crusher: 18-inch Gyratory at 3/4" MSA ·setting
(2) Feed:· Ibs
(a) Primary
(b) Secondary
(3) Product:
(<1) Ibs.
(b) Percent
* St,'ckpile: 166 lbs
d. Rodmill· S.and
(I) Rodmill : 18-inch
(2 ) Feed: Ibs
(a) Primary
(b) Secondary
(c) Ternary
(3) Product:
(a) Ibs
(b) Percent
(4) Loss:
(a) Ibs
(b) Percent
108
2 155 29
78
26.5
0x42-inch Drum
78
:66*
56.5
45
74
rines
21
2.4
Tordl
89]
100.0
467
27 467
5.8 100.0
crush,in:: Wlas
29~
50 29':'
17.0 100.0
21
27
50 :295 .
203 203
100.0 100.0
92
31.2
NP[)E:-'<-GS-L (R2-C-118)
SUB.! ECT: Mahoney Lake Hydro
f'. Product
(I) 1 bs
(2) Percent
(3) Total Processing Loss ,Percent
3. A:.:gregate Tests-Processed Quarry Stone:
a. Cradat ion
Size
4-inch
J-incl.
21._ inch
2-inch
11"-inch
I-inch
3/c.-inch
1/2-inch
3/8-inch
No. 4
No. 8
No. 16
r\o. 30
l\u. 50
No. 100
F.M.
h. Speciiic Gravity, BSSD
c. Absorption, %
d. ~~ ,\ne:eles AbIasion
~ loss @ 100 rev.
~ loss ~ 500 rev.
3"-1':1"
%
Pass
100
98
68
37
8
2
Specs _
100
90-100
20-55
0-10
0-5
2.74
0.5
e. Flat & Elongated Particles
-;,-FJatb~ht
~ Elongated by weight
Total
f. Soundness oi Coarse
A~gr~gate by Accelerated
Freeze-Thalol
-1,-T()~q--':q--bywcight(a-3-0-0~
,·v,les
33.0
2.0
35.0
(2)
0.4
250
31.3
180
~2.5
Nominal Size
166
20.8
02 :-1ar R~
203
25.4
7~9
I Ul. 0
10.3
11,"-3/4" 3/~ "-K-~--':4-----Sand
% % --=-I,=:':'A~~1 t-. -:-; ')-1 :
lOCi
90
28
6
2
1
100
90-100
20-45
0-10
0-')
2.74
0.7
9.0
1.0
10.0
3.6
16.1
100
97
62
33
4
100
90-100
20-45
0-5
2.73
1.0
7.0
0.0
-7~6
Pass
100
96
81
62
.'d
20
7
2.93
100
95-100
80-95
55-75
30-60
12-30
2-10
2.73
1.1
NPDEN-GS-L (82-C-118) . 02 Mar 8-2
MAHONEY. LAKE HYDRO DAMSlTE
TABLE II
Summary of Tests on Cores Drilled from Damsite Quarry Stone
Strength, Tensile Compressive Modulus of Poisson's
Core (Brazilian) Strength, Strength, . Elas~~city, Ratio
No. .psi . psi' PEi Exl0 psi \J
A-I 48~5** 47,810"-9.19 0.161
A-2 377~* 25,900 7.83 0.162
A~3' :580
A-I. 3860
8"-1 2345 26,700 7.43 0.163
B-2 1625 19,640
8":3 1050 1155
F-I 480
G-I 2610
G-2 2745
J-l 285 61,500 8.79 0.144
J-2 65
K-I 2255.
K-2 3225
Q-l 360
Average 2625 490 36.310 8.31 0.158
High 4895 1155 61,500 9.19 0.163
L01o1 480 65 19,640 7.43 0.144
Std. Dev. 1290 415 17,640 0.82 0.009
Cores Drilled Parallel to Clea..!'E.BS Plane**
C-l 1905 1/
C-2 28,960 J 1. 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-l 395S* 1475
E-2 3305* 1620
E-3 35,170 10.38 0.189
H-l 610
0-1 2465
S-1 lJ95
S-2 1430
~--.-~--
Average 2125 1285 24,590 11.22 0.254
High 3955 1745 35,330 12.82 0.326
L0101 1120 610 11.050. 10.22 0.189 -Std. Dev. 1135 475 12,010 1.20 0.068
1
DEPARTMENT OF THE ARMY 101 R 0 ld b. No. ~8,",2"'/'-l3~O:.:JI~i ____ _
MISSOURI RIVER DIVISION, CORPS OF ENGINEERS
DIVISION LABORATORY 16 FEB 1982 ,
OMAHA, NEBRASKA 68102
Subject: Petrographic Examination of Quarry stone
Report Series No.8·
Pro j e c t : Mahoney Lake Hydro
Intended Use: Concrete Aggregate
Source of Hat~rial: Mahoney Lake Hydro DamsitE' Quarry, Alaska
Submitted by: Director, North Paoific Division LaboratolY
Date Sampled: ________ ~ ____________ , Date Received: __ ~14~~J~an~~8~2~ ___________ ___
Me t hod 0 f Te s tor S pe c i f i cat i en : __ C_R_D_-_C __ l_2_7_-_6_7 ______________________ _
Refe(ences: __ ~N~(~)r~th~'~P~a~c~i~f~i~c~D~l~'V~l~'S~'~i~on~~L~a~b~o~r~a~t~(~)r~\~'~I~\e~g~u~·~~s~t~N~o~.~E~8~5~8~2~9~5~O~4~~d~a~t~e~d~ ___ _
12 Noyember 1981 and NPDL w/O 82-C-118.
SAIVIPLE IDENTIFlCATION
MRD Lab No. 82/30H. Sample of quarry stune for use as concrete aggregate taken
from Mahoney Lake Hydro Quarry, Alaska.
TEST RESULTS
1. Pelorgraphic 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 orthuclase,
is abundant in the rock and is generally finely crystalline. It is closely
associated wi th tremoli te having a lineatE'd trend. f\. small arllount of
chlorite is also present. Finely crystalline magnetite occurs in the lines
of schislosity. A considerable amount of pyrite is distributed throughoul
t.he 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
stnined 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 ~ulfate expansion. Particle
shape may be a problem with this rock due to the closely spaced joint system.
MRD FOR"
MAY 70 I 15 EDITION OF FEB 67 IS OBSOLETE.
D i 1'(;(; Lor, Mill) ] ,abura lory
ll:b
NPDEN-GS-L (82-C-l18) 02 Har 82
TABLE II
MAHONEY LAKE HYDRO-Summary of Tests on Cores Drilled [rom Damsi t e Quarry Stc)J}e
NOTES: I! Laboratory Test Methods:
a.· RTH 113-80, "Standard Hethod of Test for Determining the Splitting
. Strength of Rock" (Brazilian MethJd)
b.RTH lli..;.80,· HDirectTensile Strength of Intact Rock Core Specirr.ans"
(ASTM D2936-78) .
. . '. .
c .. RTH 111-80, "Unconfined Compressive Strength of Intact Rock Core
Spe~ imans " (ASTM D2 936-78)
d; RTll 201-80, "Elastic Moduli of Rock Core Specimans in Uniaxial
Compression" (ASTM DJ148-79)
2/ All tests on nominal 1!-4-inch diameter cores except as noted.
3/ Failure occurred through epoxy at end of core speciman, test resIil t not
included in computation of average and standard deviation.
* Test made on nominal 1 3/4-inch diameter core.
** Revised 02 March 1982.
r
--------------------------------r-----n-l
t 11 I
--r------l
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L-\I I:
t-0 .O
z
W
i..J
:r:
w
Q.
tjJ.o
-,
<
I
u
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I :
i
r=
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I [
\
!
I
I
I
I
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r
W
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I I-
, I
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+----I---~
I I-
i +-------+------4-~
I
--I
I I
t I
1
--
I
1---_ I
I r----t I
+--+-! I j I------T--------r--------41--+-1 I
(!i
F
----+-----+--+-1 --~ i -I [ I
-oJ---i_L-_~-_~t----!Jj
'(1,.1
I
~=======r====:::;:::========r"=-C='T=i:.=-=.:f'=_"=c=,,=,=,.,=,A=,, G=re=-~ __ =:\'::;r_,=r~l\=t=Y=~=_l==' .Ji' r ,J: )
~~;;~~'+~B" High A:~':;~';~::nC--lr:"I~:'EY l.AKE HYDRO I I ! ,~~-:JI:-'--'--,\ l-,lska - -----------~
i 1828,\ j. Low Alkali Cement "'U~'~-::-:-------~------1
I -1 i Llboratu,y n«111l,\,!('lllred sand from Do.r;;sitt
~ __________ L __ ~j ______________________ j l-~~~-~~y-~,~(jne, jl"m~it: __ ~ua~~_~,_ A~~_~_k;~_: --J
I'" -M_,,, II ~~~ ~~;,~{ 1 "emen: -~~ -, "hi reha 11, p,\ i
I f------0 .4tC------------------<
I ,I Blend ()[ (lrehOn, [daho, <lnd LE::hi"h Tvf"::
i
l
I ~:-,,-,--_ \ ~1I~' 1 r, ~; e :lll' n t s __ _________ _ _ __ ___ _ _ _
i 82-C-I Pi
1 I! -' ...:-' -
, I! L _________________________________ I l ____ _
r-
: . : J i' I I
i I ,j \ J, I • ~ • J
'______J ____________ ~ i _. ___ . __ . _____ . ..L __ . _______ •• _______________ ''"~, ____ " _____ ._ .•
. I. JI_.
APPENDIX C
ECONOMIC EVALUATION
I NTRODUCT ION
APPENDIX C
ECONOMIC EVALUATION
This appendix describes the methodology used in the economic analysis for
hydropower development in the Ketchikan area. The evaluation was based on
economi~ benefits that could be derived from hydropower development alone
and was accomplished by comparing the benefits to accompanying costs. The
benefits of hydroelectric power were measured against the costs of
providing equivalent power from the most likely alternative sources, such
as diesel. The economic analysis was based upon a power-an-line date of
1989. The projecti nsta llment date was determined from the community's
future power needs, as posted by the Alaska Power Administration's load
growth forecast and a time allowance for project construction.
PROJECT COSTS
Detailed cost estimates of the tentatively selected plan, Mahoney Lakes,
and the NED plan, Lake Grace, are contained in Appendix D. The total
investment cost of Mahoney Lakes is estimated at $50,084,300 and for Lake
Grace, $94,023,600.
Interest During Construction (IDC)
IDC was determined by applying simple interest of 7-7/8 percent to a
uniform expenditure over a 4-year construction period. For Mahoney Lakes
and Lake Grace IDC was $6,157,000 and $13,517,000, respectively.
Operation, Maintenance, and Replacement Costs (OM&R)
Annual OM&R costs were provided by the Alaska Power Administration and are
included in Appendix F. Annual OM&R costs are $394,900 for the Mahoney
Lakes project and $607,000 for the Lake Grace project.
Total Annual Cost
The compound interest charge on costs incurred during the construction
period of a project was considered a cost of the construction phase and was
added to the first cost to establish the total investment cost. The
investment cost was transformed into an average annual fixed cost by
applying the capital recovery factor associated with the 7-7/8 percent
interest rate and a 100-year economic project life. By adding OM&R costs,
a total annual cost was established to determine comparability with project
benefits. The estimated average annual cost for the Mahoney Lakes project
is $4,341,500 and for the Lake Grace project is $8,160,400.
PROJECT BENEF ITS
The benefit value of hydroelectric power was measured by the cost of
providing the equivalent power from the most likely alternative sources.
The Federal Energy Regulatory Commission (FERC) determined that source to
be diesel for the Ketchikan area and supplied the costs of diesel generated
electrical power. A benefit for local employment was also identified to
show the impact of the project construction on the local economy.
FERC Power Values
The at-market valu~s of dependable hydroelectric power delivered in the
Ketchikan area were based on the estimated costs of power from a 6,896-kW
diesel unit, with a heat rate of 9,380 BTU/kWh, operating at a 58 percent
plant factor, and a 35-year service life. The capital cost was $455/kW,
and fuel and lubricating costs were $1.14 and $3.69 per gallon,
respectively.
With Federal financing of 7-7/8 percent, the at-market value of dependable
power is $58.93/kW and $88.25 mills/kWh without fuel cost escalation.
Price levels are from October 1982 prices, adjusted by the Corps of
Engineers from January 1982 price levels reported by FERC.
Fuel cost escalation above the inflation rate was used in the energy benefit
analyses. That portion of the adjusted at-market energy value that is a
direct result of fuel cost was escalated for 30 years beyond the power-on-
line date and then held constant to the end of the project life. Real fuel
cost escalation rates were based on the 1982 Data Resources Incorporated
Energy Review Report. Escalation rates and the resulting value of energy
are given in Table C-l.
Table C-l
Real Fuel Escalation Rates and Value of Energy
Period
1982-1985
1986-1990
1991-1995
1996-2000
2000-2019
2020-2089
Escalation Rate(%)
-0.53
4.23
3.71
2.65
3.53
o
Year Energy Value (mills/kWh) 1982 --~~~8=8~.2~5~1~7~~~
1985 86.94
1989 (power on line) 103.24
1995 125.63
2000 142.44
2019 (end of applied
escalation)
2089 (end of project)
270.32
270.32
1/ 5.29 mills/kWh of each energy value are from O&M.
C-2
Transmission Losses
Transmission line losses for a hydropower project were estimated using data
available from Ketchikan P~blic Utilities (KPU).Historic rates indicate
an average annual energy loss through the entire KPU distribution system of
3.3 percent. An energy loss of 2.0 percent was accounted to the hydropower
project wlth remaining losses accounted to the transmission network. to be
absorbed by the local utility and reflected in their rates to users.
Capacity losses were estimated to be 5 percent.
Credit for Energy
The demand for energy was based on the jlllas~:1 Power i\dministr'dtion' s
"medium case load forecast ·as shown ln Figure C-l. A use pr'iority was
established to determine when energy from a proposed hydropower project
could be used to meet any of the demand. Use priority is shown in Figures
C-2 and C-3 where firm energy from exlstirg hydropower is used first, firm
energy from Swan Lake is used second, etc. .
Fi rIO energy from r~ahoney Lakes or Lake Grace was counted as a benefit to
the level of energy that would fulfill dema~d. Power on line was
considered as the first of the ye~r, 1989, and any firm energy from a
proposed hydropower project that was used to meet demand would replace
energy produced by diesel. The value of the energy used for a l-yea r
interval was determined by the escalated mill rate of diesel energy a-;, the
end of that year. The dollar value of each year of energy benefits was
then discounted to 1982 dollars to deterrni ne the average annual firm energy
benefit. expressed in 1982 dollars, for the life of the project.
There is an identified demand for Mahoney Lakes secondary energy. This
energy would be available to meet demand on a statistical average greater
than 96 percent over the lifetime of the project. Therefore, secondary
energy from the Mahoney Lakes project was counted as a benefit, to the
leve"1 of energy that could fulfill cE:mand, beginning in 1998. The value of
this secondary energy was considered to be the value of diesel energy it
would replace.
No secondary energy benefit is claimed for the Lake Grace project because
there isno clearly identified demand for its use within the foreseea~le
future.
Average annual energy benefits are $7,493,200 for ~1ahoney Lakes and
$13,191,000 for Lake Grace.
~apacity Be~efits
The d8nand for capacity was based on the Alaska Power Administrationts
"r.ledium case" load forecast, Figure C-1. A use priority was estab"lished to
uetermine when capacity from a proposed hydropower project could be used tc
meet demand (Figures C-2 and C-3). Capacity from either hydropwer project
cou:d replace the use of existing diesel as soon as the project came on
line in 1989. However, the hydropower project \'muld not Gisplace the
installment cost of the displaced diesel at that time. In 1994 demand
(-3
r-----------------------------------------------------------------------r~
1945
HISTORIC AND ESTIMATED ENERGY DEMAND
19~
LEGEND
-------'----HIGH CASE
_.-._.-.-.-.-.-MEDIUM CASE iSEl-ECTEDI
-----LOW CASE
19151S
APA-R!VISED
12/15/82
HISTORICAL
1960 1965 1910 1975
YEARS
1980
I
!
I , , , , , , ,
;,' ;~. '" .-/ ....
~"."
" , , , . , , , ,
ESTIMATED
1985
, , , ,
1995.
" ,
, ,
280
260
240
220
ICO
80
60
40
20
r-----------------------------------------------------------------------T715
1945
HISTORIC AND ESTIMATED PEAK CAPACITY
LEGEND
19S0
------------HIGH CASE
.-._._._._._.-MEDIUM CASE ISELECTED)
-------LOW CASE
APA-REVISED
12/15/82
HISTORICAL
191515 1960 19615 1970 111715
YEARS
" " , ,
, " ,
,
, , , ,
," 70 ,
615
60
SIS , ,
I ...-
; " , ,." I ,.
I ,,-, ."
I " I ,,-
I ./
I '"
50
i 415~
40,..
I I-
) ",'
," ." I ,-"
315~
c
30 U
I i ,,-
J,'
ESTIMATED
1990 I,"
25
20
liS
10
15
I)
2000
Figure C-1. Historical and estimated power demand, Ketchikan
.>
I
I
I
I I
2:!°r'~-'-------" ,-----_ .... .,.
20( ESTIMATED ~
l&Ot ENERGY ~~
----------~
". I
I
IsOt DEMAND )~"'
!40
~
'" ~1:20
>-
U>
::i 100
Z
101
4
L 2i
LAKE GRACE f'"!RM ENERGY
~~~~~~~~-------------------.------------------.. --i
I
I
I
SWAN LAKt: FiRM :-~N!:RGY
1
EXISTING HYPRO?OWrR FIRM ENERGV
I
041--'--1--l---'---+--~--+--4-.--.~+--.. L-.~-L-....f--""'-·-'--_'---+-_-+1_-41_-'---1.
~980 !~5 i9'110 1"5 2000
>-1-.
()
"" ~50
YEARS
._---------------_.---_._----------_ .. ------------
ESTIMATED CAPACITY ~ •• ~.o ••••• ~ ••••••• ~ •••• o •• ~ ••
•• 6 ••• 0 •••••••••••••••• ~ •• ~~,
~o.a •••••••• ~c ••••• ~.8~~ ••••• ~ • .. ~ .....•.•..•.•.•• ~~ •.••..... ~.
:::::::::::::::~::~~::::::::
•• ~ •• e ••••• ~ ••••••• ~Q ••• ~ •• O
.~ .. Q..... • •••• $ ••• ~ ••••••••
'.a~ •• ~.. • ••••••••• ~ •••••••• a ....... . .. ~~ ... ~ ... -~-.... "'-~-.....
••• .~YI~TIt.lr.: r"l1"C:1=' I ••••• .. • ••• Wl."'L ~ 1t'~7 •• ~ Q', .... ;-., •••• ill
L/i,KE GRACE
U L..-.n~~~.L.I.£. . ___ J
I
20
-'-~---"'-------ll
EXISTING HYO,",OPOWER
1 I -L._-L __ ~>_-'-_·..1.L_-'-........ _~I_.J....._ -,---,---,--.J
1"0 11l>~ 200(' ZO\')~
Yl:·f/S
Figure C-2.Comparison or power demand with addition 0'( the Lake Grace
project to exisilng facilities.
I
I ~ I
I ~ .
.lit.
220
200t
leot
180
14
ES jlMATED ENERGY DEMAND
a OIESEL
.MAHONEY LAKES FIRM ENERGY
~ '20
>-
(!)
::i'OO z
~
30 SWAN LAKE FIRM ENERGY
eOSECONDA~~
40
20 EXISTING HYDROPOWER FIRM ENERGY
YEA .. S
70~-------------------------------------------------------------------.
60
........................ •.••..............•..•...•
::::::: E)~ISTING·:::::·· :.::::::::::::::. ' ..••••.•• oe........ . ..••..•..•....... .•............... . ....... ~ ........... . ............... . ............•......... •....••..•• . .............•....••..... ..... . .....•......••••..•••..... .. . .•....••...•.........••...•• ••• ::::::::::::::::Ql~Jl~~!::::::: • ..........•.............•............
MAHONEY LAKES
SWAN LAKE I
I
I· EXISTING HYDROPOWER I
O+--~~--~~--+I--~-4--~~--~I--~~~~~~-Ir-~--L-~--L-~i· ~~--~~I
1980 I !tall '"0 1"11 20·00 200~
YEARS
Figure C-3.Comparison of power demand with addition of the Mahoney Lakes
project to existing facilities.
I
I
I
would exceed. all presently existing capacity,including diesel and Swan
lake, and would require the installment of new capacity. The Mahoney Lakes
or Lake Grace projects were considered as replacement for this new (diesel)
installment. Capacity benefits for hydropower were, therefore, claimed for
the full capacity of the hydropower project, minus transmission losses,
beginning in 1994. Annual capacity benefits for the MahDney Lakes project
are $600,400 and for the Lake Grace project, $806,000.
Use of Exist~ Diesel
The economic analysis for determining capacity benefits was simplified by
the following ass:Jmptions on the use of I'x-isting dif~sels.
·When a hydropower project comes on line iil 1989 it would replace the
use of existing diesels to the extent of its capacity. The existing
diesels would be retained.
·Existing diesels would again be used when capacity demand exceeded
the hydropower project's capacity. Beginning in 1994, use of existing
diesels would be counted as replacing the cost of new installed capacity
that would have been required if t~e hyorop~wer project would not have been
constructed.
·The use of capacity from the ne~ .. hYCll'opower project would eliiilinate
the need for continued use of existing diesel for that capacity, therefure,
replacement cost at the end of the life of that diesel would be eliminated.
·Use life of existing diesels would be extended, in calander years,
since the level of use b~yond the 1994 date would be less than if the
proposed hydropower project had ~ot been constructed.
Therefore, the claim of full caracity benefits to the extent of the project
capacity, beginning in 19S4. and retention of the existing diesel to meet
future peak loads, would be equivalent to displacing new diesel
installments and replacing expended diesel units as they would occur.
NED Employment Benefit~
Project benefits for employment are claimed to snow the impact of project
construction on the local economy. f\ cClrr:rnunity is declared eligible for
the employment benefit claims ~ased on a condition of persistent and
continuous unemployment, for VJhich the l\(;l:chikan area qualifies.
The benefits are attrlbuted to the amo0nt of unemployed skilled and
unski17ed workers an area can contribute to the construction of the
project. Only unemployed 'Iabor can be claimed, as there is no econom-ic
benefit entailed in the use of otherwise employed reso~rces. The amo~nt
earned by this group is amortized over tne project life and is expressed as
an annua1 amount. Coefficients used to determino employmenc benefits were
derived from studies of and exp~rience with sisi12r projects in the area.
NED emp-ioy;nent Llenefits ay'o:: de-cailed ir.T3.bl~~ :>2.
C-7
Table C-2
NED Employment Benefits, Mahoney Lakes and Lake Grace Projects
Benefit Computatio~ Mahoney Lakes
Project Construction Cost
(lessIDC, E&D, S&A) $ 37,660,000
11,298,000
7,908,600
1,581,700
Labor Cost (30%)
Sk ill ed Labor Cost (.70%)
Local Skilled Contribution (20%)
NED Skilled Employment (43%)
Unskilled Labor Cost (30%)
Local Unskilled Contribution (75%)
NED Unskilled Employment (58%)
Total Employment Benefits
Annual Employment Benefits
ECONOMIC ANALYSIS
680, 100
3,389,400
2,542,100
1,474,400
2,154,500
'169,800
Lake Grace
$ 78,928,000
23,678,400
16,574,900
3,315,000
1,425,400
7,103,500
5.327,640
3,090,000
4,515,400
355,800
Economics of the tentatively selected plan and the NED plan are summarized
below.
Average Annual Benefits
Average Annual Costs
Net Annual Benefits
Benefit-to-Cost Ratio
l"1ahoney Lakes
(Selected Plan)
$ 8,263,400
4,341,500
3,921,900
1.9
Lake Grace
(NED Plan)
$ 14,353,800
8,160,400
6,192,400
1.8
This analysis was based upon real fuel cost escalation. If no fuel
escalation above the October 1982 price level was to be considered, the
economics would be:
Average Annual Benefits
Average Annual Costs
Net Annual Benefits .
Benefit-to-Cost Ratio
l"1ahoney Lakes
(Selected Plan)
$ 4,835,900
4,341,500
494,400
1. 11
Lake Grace
(NED Plan)
$ 7,759,000
8,160,400
-401,400
0.95
Therefore, if no real fuel cost escalation was considered in the study
analysis, the Mahoney Lakes project would be economically justified, but
the Lake Grace project would not.
C-8
APPENDIX D
MAHONEY LAKES PROJECT PLAN DESCRIPTION AND COST ESTIMATES
i\iJPEND I X D
MAHONEY LAKES PROJECT PLAN DESCRIPTION AND COST ESTIMATES
PRUJECT DESCRIPTION
The tentatively selected plan would consist of a multipipe lake entry into
Upper Mahoney Lake with most of the penstock running through the unlined
penstock tunnel to the power plant, which wo~ld be located near the lower
Mahoney Lake (Figure 0-1). The upper lake's storage capacity would be
increased by construction of a dam across the lake's outlet into Upper
Mahoney Creek. The power plant would contain three power units and would
be remotely controlled from Ketchikan. The tl'ansmission line would tie
into the Ketchikan Public Utility (KPU) system at Beaver Falls, 5 mlles
from Mahoney Lake. Tailrace waters wou1d be discharged into Upoer Mahoney
Creek upstream of the lower lake to maintain the flows needed for salmon
spawning. Access to the project site would be by helicopter, seaplane, and
boat. An access road would connect the dock and seaplane float areas on
George Inlet with the living complex and the power plant. Access to the
portal and dam areas would be by helicopter.
Waten'iays
The lake would be entered 225 feet below its existing surfdce. The entry
would be accomplished from a la-foot horseshoe shaped tunnel excavated from
a portal on the lower Mahoney Lake side of the mountain (Figure 0-2). The
excavated material would be disposed of to the north of the portal, so that
it would not interfere with the penstock. The tunnel alinement was
selected to avoid an avalanche area located to the north of the portal.
The scheme would include an underground multipipe intake chamber, an
unlined penstock tunnel, penstock, and other features. These structures
would constitute the waterways to transmit water from Upper Mahoney Lake to
the aboveground powerhouse located near t"1ahoney Lake.
Multipipe Chamber and Lake Entry
The multipipe chamber, Figure D-3, would house a 36-inch remote control
spherical valve that could be operated from the powerhouse. The chamber
size would be dictated by the length of pipe required to reach the lake.
If the rock near the lake is found to be sound, the chamber could then be
moved closer to the lake and the multipipes could be shorter and the
chamber could be smaller. The chamber would be vented by an a-inch hole
drilled from above the reserVOlr near the top of the mountain.
The sequence for lake entry would be as follows. After the chamber would be
excavated, nine holes would be drilled approximately 10 feet into rock
toward the lake and a 14-inch pipe would be inserted and grouted into plac~.
A concrete head wall would then be placed around the pipes. A 14-inch gate
valve would then be bolted on each pipe. A hole large enough to accept a
12-inch pipe would be drilled in the rock through the open gate valve and
14-inch pipe to within several feet of the lake. A construction mani-
fold containing a stuffing box would be bolted to the gate valve. The
remainder of the hole would then be drilled. The drill would be extracted
and the valve closed. A 12-inch pipe containing a coarse screen would be
inserted into the manifold. The valve would be opened and the pipe pushed
partially into the lake and secured with set bolts located near the valve.
r-----------------------------------------------------~----------------------~c-~"-~ ... ~-~~~,----------------------------
+ + +
+ -+
+
"t'P£R MAHOfEY LAKE .-
Ila"."~ /" ~
!J.A!l
ICAU II I'UT
..,. 2 400 ? r
+ + +
M4h0*EY LAKE
CL" .,,'
---1 +
+ +
GEORGE INLET
SEAPLANE FLOAT
DOCK
~"+ ~-
TrJP06lIfAPH'f BY AERIAL MAPPING FROM u.s. FOREST
SEIMCE INS AERIAL PHOTOGRAPHY BY HoW. BECK
AND ASSIOCIATES. HORIZONTAL AIrf) VERTICAL CONTROL
BASED ON US6S QUADRANGLE MAPS
MAHONEY LAKES
SITE PLAN
Ir.IIr.I)
~ RIVERS AND HARBORS IN ALASKA
I/,.sl;,';l...~ SOUTHEAST HYDROELECTRIC POWER INTERIM
Alaska Dlstnct
Figure,
0-1
UPPER MAIIONEV
LAKE-EL. 1"f5~ W'''''ooft
'Infair~ Chamb,r
SM Plate D-A-3
P~n5loclr T unn~1
tOO -
PROFILE
IoCALl" '((T
o 100 400
/--FtJr/~/ and rl.T1I7t!/ F~cavollon
oochar~ Road
/,cvwerfJouse
_ (ltF!? MA 4('IiFf
LAKE EL 84
MAHONEY
WATERWAYS
LAKES
PROFILE
"'" IIIIiII RIVERS AND HARBORS IN A l ASK"
USArmyeorp. SOUTHEAST HYDROELECTRIC POWER INTERIM
ofE ..........
Alaska Dlstnct
Flgur.:
0-2
I",
,
I'
(ft>ER
MAHONEY
i.AK£
PARTIAL PLAN AT INTAKE CHAMBER
SCALl I" f((T
<00 400 IQO .zoo
Normal VVot/!r 5Jrfacl!
W,th 25' HIgh Dom-£L 1'180
//
1. _"'-_. ___ _
Mud
E LE VATION AT INTAKE CHAMBER
ICAU ... "
tOO
o __
-
~'6' J"O' J"O' "'61
~~
-tl
'\::) "-\.
'", , , ,
:? ::1 ..,
t1L-
INTAKE PIPES AT '.3 Of' '1',,"9
"CTI" 0 _:,,;' ......
}-
I
4' CONCRETf WALL AT FACE OF INTAKE CHAMBER
SECTION 0
ICAL( IN '((T
·f
~~-1(
t
i~
KeTW't 0
-to_I
CaorM ,5c..r~e"
TO'-O'
ENLARGEMENT AT INT,AKE CHAMBER
~8
ICAU. 'UT • 9 10 10 ,.
$0'-0'
I~"; x 10'-0' P,PI
gUIf:k gTouft!d
Gatt! I/al>,t!
/SfUfF"q
_, ~I __ ~BOX ~u
GrrJU tt!d rock_"
bolt
, 4'-0' r-------. Concr~t6
INTAKE PIPE WITH MANIFOLD FOR PLACING PIPE
---j
!
NPmot. Control
Sph(!Tical Yolve
SECTION 0
SCALE Itll 'EET
o I
~n.5tock
MAHONEY
LAKE TAP
'-Wan( rold for
J)lactn9 tJllJ~
i7 tJt> 'frnovt'd
arf~r Ins fa 'atlon,'
LAKES
SCHEME
r.IIr.II IIiIiII RIVERS AND HARBORS IN ALASKA
USArmyeorp. SOUTHEAST HYDROELECTRIC POWER INTERIM 01 Engineers
Alaska Olstnct
Figure.
0-3
Tne gate would be closed and the manifold removed. Aft~r all nine Dices are
in place, a perman~nt pipe manifold and reducing cone would be attached and
the 36-inch penstock containing a remote control valve would be installed.
The 14~inch gate valves would be used as backup for the remote control
valve.
An alternate method of lake entry would have been by a lake tap. The tap
also would have been accomplished from the e~cavated tunnel and would have
included the lake tap, rock trap, power tunnel and control gate chamber. A
single lake tap was considered for' a depth of 175 feet below the existing
lake surface. The single lake tap was more costly than the multipipe lake
entry design and the ~75-foot depth did not optimize th~ storage capacity
of the upper lake.
A double lake tap to a final depth of 225 feet was considered to optimize
lake storage. Because a single lake tap could not be accomplished at the
extreme depth of 225 feet, a two-stage process w~s considered. The first
stage would tap the lake at a 1 75-foot depth,lcl€ -jake would be drawn down,
and then the second tap would be executed at a 225-foot depth. Optimizing
1ake storage by a second lake tap was not C0~t effective, however.
Penstock
The penstock would be a 36-inch-diameter, S,370-foot-long, all weldea
structure supported on concrete pi ers at approx irnate ly 40 {:;:~et on u~nters.
The penstock would extend 4,000 feet frCill the valve control charnbe;~ tllro~;gh
the tunnel on a slope of approximately 1 on 3.2 to the portal, and then
continue on the remaining 1,370 feet to the aboveqround powerhouse following
the ground contours. The penstock would trifurcate into three penstocks
immediately upstream of the powerhouse valve room. Each penstock wou1d
connect with a valve in the valve reom. DOlfl:!stredlTI of each valve, a
penstock extension would connect to a tur-oine.
Surge Tank
Preliminary stuaies indicate a surge tank is not y'equired for tins pt'oject.
Deflector gates would be installed so flow could be diverted from the
Pelton wheel if load rejection occurs. Valve closing would be contro11ed
to prevent any possible water hammer.
Dam
The selected plan would include a 2S-foot-high dam constructed of heavy
gage binwall cells (used conventionally for retfiining walls)~ as shown in
Figure D-4. The cells would be tied together and filled with rock with the
top layer containing heavy riprap to prevent rock movement during peak
runoff periods. The cells would be keyed into the rock sid~walls of the
channel and a concrete cutoff wall Wall Id he placed at the heel. The
upstream face would have a welded steel me~brane. A 40-foot-~ide section
would be set I foot lower than the adjacent sections to confine the normal
streamflow to the centel' of the dam. Du,~i nq high runoff per-lods, flow
would be over the dam's entire length. Tne binwall type of dam would
utilize the surrounding materials and reuuirE a minimum of heavy equipment
for construction, as access wo~1J be by hel icopte r only. Wire mesh and
rock bolts would be required on thE left bank to retain dny loo~2 rock.
The dam '~ould be construeter:; after Q0wey' on 1 i ne has bp.en accomp 1: shed, so
that the 1 ake sut'f ace cou 1 d be draf':1 (jr)'tin ~}e 1 uw the 1 ake out -: et i nvey''c
elevation.
D--5
2000 -
1980 -
1960 -
1940 -
EL. ,.80 --IF==:!::::J!
WELDED STEEL FACE TO 81N
CONe. CUTOFF WALL.
1'-6' WIDE X 3' DEEP
3+60 3+80 4+00 4+ 20
STEEL BIN WALLS (RETAINING WALLS)
FILLED WITH ROCKFILL
STRIP EXISTING MATERIAL
4+40 4+60 4+BO
DAM CROSS SECTION a OUTLET PROFILE
10 0 '8 f
SCALE IN FEET
2100 ~-------II
2110 ___ ---------t-----....
ZlZO -
r
,
leO
,
140
I
lID
I
100
,
10
I
to
DAM SITE
TOP OF III SET OF BIN WALLS
WITH I' OF FREE BOARD ABOVE
THE RESERVOIR POOL ELEV.
I I , ,
40 10 0 10
I
to
I
10
,
100
I
110
I
140
I
Ito
I I
leO 200
-2100
-2080
-2060
-2040
-2020
-2000
~ 1980
-INO
-1.40
{)1M a SEY ION
~.?~~~~ ____ O".10~---------------------------------------4
SCALE IN FEET MAHONEY LAKES
BINWALL DAM SCHEME
Ir.IIP.II IIiIiII RIVERS AND HARBORS IN ALASKA
~SE~~ SOUTHEAST HYDROELECTRIC POWER INTERIM
Alaska Dlstnct
Figure.
0-4
Rockfill and concrete gravity designs were investigated for dam heights of
25, 50, and 75 feet. The binwall design, shown in Figure D-4, was limited
to a height of 25 feet by its own mechanica1 chat'acteristics. f\ "no dam"
scenario was also investigated.
The rockfill dam had side slopes of lV:2H and a top width of 20 feet. The
upstream face of the dam was designed with a l-foot thick reinforced
concrete liner that would extend to bedrock to act as a foundation cutoff
wall. The spillway would be an ungated side channel excavated into the
solid rock of the right bank. Spillway excavation would supply the major
portion of the construction material for the rockfill dam.
The concrete gravity dam was of a conventional design, const~~cted on
bedrock, with an ungated spillway over the centerline of the creek bed.
Aggregate would have to be barged in; the most probable source would be
from Price Rupert, Canada, a haul distance of approximately 120 miles.
The concrete gravity dam was more costly than the rockfill dam and had no
special advantage to warrant the additional cost. The 75-foot rockfill dam
was found not to be increment.ally just ified over' the 50-foot height. The
25-foot binwall dam was less costly than the 25-foot rockfil1 dam. T~~
final comparison for do.m selectioil ' .... as betwet:~n the no dam scenario, the
25-foot binwall, and the 50-foot rock~ill dam. The final dam cnoice was
the one that created the hydraulic and economic conditions that opti'nized
net annual benefits. A plot of the dam types, associated plant size and
plant factor, and the resulting net annual benefit are shown in Figure 0-5.
PO'v',er Plant
The aboveground power plant would be located approximately 500 feet
upstream from the eastern edge of the lower lake. The discharge would be
spilled into a stilling basin, then into Upper Mahoney Creek via an unli~ed
channel, with negligible power release. The centerline of the trifu~cation
distributer would be approximately at elevation 90 feet. The powerhouse
would contain three synchronous generators with nameplate ratings for each
unit of 4.8 MW (14.4 MW total) at 600 rpm. Each generator would be driven
by a Pelton wheel turbine with a design head of 1,820 feet. The powerhouse
structure would house the generators, turbines, a 15-ton bridge crane. and
all other equipment required for operation afld ola-lnten;mce. Remote contrc1
of the power plant would be from Ketchikan through a carrier communication
system.
The hydraulic capability of this system is 14.4 M~ with 38,090 MWh of firm
energy and 51,390 MWh of total average annual energy. Capacity and energy
values were based on a 30 percent plant factor, 90 percent power factor,
and a 2-year critical water period, based on 48 jears of hydrologic
f'ecords.
Alternative plant sizes with varied plant factors were investigated.
Figure 0-5 plots the net annual benefits of the var-iolls combinations of
plant characteristics considered. The se1erted plan is that combination of
facilities that optimizes net annual bent~fits.
D-7
40
~39 o o
'* )( -~38
IL.
UJ
Z
UJ
IX)
-'37 <t ::> z z <t
I-
UJ
Z
15.2
19.1 MW
18.7
145 MW _..!.3.6 MW
. /---- -'2 4 MW /' ... !......
/ ............
/ ......... / ...... , ._-.---"'-,
/ "
I ' I '.9.7 MW
I 10.9 MW
• 17.4 MW
10.4 MW
8.5 MW
35~----~------~------~----~------~------~----~
15 20 25 30 35 40 45 50
PLANT FACTOR
NO DAM
- - - - - - -25 FOOT DAM
- - - - -50 FOOT DAM
MAHONEY LAKES
NET ANNUAL BENEFITS vs.
ALTERNATIVE PROJECT VARIATIONS
~ ~ ........... MIl ..... "'-1,5«"
':::;,:::-IiOVTMEAST HT~UCTAIC ,... Itf11!MII
oIIIoaINDIMIIt
0-5
~ __________ --______________ -L ______ ~ _____________________________ ~
Alternative powerhouse sites also werA cons~~ered, which could be located
as far as 1500 feet upstream from the lower lake to reduce the effect of
tailrace waters on salmon spawning. The major problems encountered were
powerhouse locations within a flood~ay dnd/or penstock crossings of
avalanche areas, which would requir~ costly engineering solutions that
could not be justified.
The Mahoney Lakes project power would be de11vered to an enlarged Beaver
Falls SUbstation and then be tra'lsmitt~d OV2i' t(]i~ iZPU system for
distribution. The transmission line route would follow the shoreline
contour more than 1/8 mils fn)n1 the srnr:;line so 2S not to j(d:etfere with
eag 1 e habitat. The route WOU! d trave\hse \'ugged topography bet~,een -; ower
Mahoney Lake and the Beaver Fa i I r.; ::::ubs:>'tt i on and wou 1 d requi re use of a
helicopter. No road access wou1d be provided.
The transmission line to Beaver Fdl~s would be 4.9 miles of single wood
pole construction with a potenti21 of 34.5 kV and a capacity of 18 MVA.
The overhead conductors would be #1;0 Ars~ wi~h~ut overhead ground wires.
The 34.5-kV system was chose~ for power transmission to match existing
faci-lities. Voltage regulaticil fr:)1J1 the i~dhoney Lake power' plant to
Ketchikan is 2.5 percent and is acce~table. An additlon to the Beaver
Falls substation is proposed to provid2 switching and ~ower energy to the
existing system. An oil filled circuit breaker would be remotely
controlled fr'om Ketctlikan Vla .3 can'ier communications system.
The proposed right-of-way would be 75 feet wide and would run over lands
controlled by the U.S. Forest Service (Tongass National Forest), but
selected by native cO"porations under the ~erms of the Alaska Native Claims
Settlement Act (Fi9ure D-6). Sasec an topographical maps with vegetation
overprint, the entire line would require essenriJlly continueus clearing.
Small shrubs and bushes would remaifi. Other clearing would be en a
selective cutting basis to~emO\i,~ "dang:''-'' t;'ess. MeY'c!l~ntable logs would
be removed ',vhet'e feasible and iii: other mater'ia.ls would be burned, chipped,
or' left in place as deterlTP,12d ty the U.~:. J:orest Service after establish-
ment of the line location. Construction and illainti:.:nance of thA trans-
mission line woula be by helicopter and a clear~d lO-foot-wide hiking trail
would be provided for inspection acces~.
Project /\ccess
Access to tne project site wou1d be by water from George Inlet. by seaplane
or by helicopter. A dock and seaplare float would be constructed as part
of the project and connected to the construction camp by 1/2 mi ie of road.
A 5-mile road to the project from the Beaver Falls site was considered.
Road access was more costly th~n the selected as ess, incl~ding a
construction camp, living acr::omlilodat.ions rGr UV,l operatin~J cr2WS, and water
and sewer systems.
Access to 1.~e powerhouse from the camp area wo ld be by an dPp~oxinlately
3/4-mile road. Roads would be 15 feet ~1de) w th 4-foot shoulders. The
maximum grade would be 8 percent, havino 1 mln mum curve raOlUS of 50 feet
and a 20-mile-per-hour~ a.veras;e desi lJr1 s;.~t~J~~(j.. avir:g of t.he ~"oads is not
consid~red necess~ry.
\
L
",
2JO()·
1100
'--' ... /
U~i; ,~
j
..... _.....lillilQllwrr'
~-'-y~--~----~~--~
-~
. .ac
I , I ,00 ~
,/ \ 'i i (
FOX ' NATIVE i ORPORJl.TION USFS ~,.. r-...~--+=~~U~S~F~S~:':"':':;':;"'~·~:;;'::;:::'~~'!-.--"""'· CAPE FOX ~. "'.. < I , ~ ~ ~a ~APPLICATION '\\
"
!.I..AfI
!!IUU IN "n
~-~~-MAHONEY LAKES
LAND OWNERSHIP
Figure:
0-6
34 35'<--______ . .I74.§,R91~ . ___ _ t
l l!I J f./lllf'tS ANO HARBORS ,,.. ALASKA
I ':t:;;;:.;:::-S,)UTH~A!i1 ~YDROflEGTI'UC POWER INTER'''''
. ___ ..:::~:;5 ~ ___ . ___ "" .. _ Al"'a[),s",,, I
• ..6: _ cw K;;r~",'ioIlM"''"W'' ...La.;lI __
Portal and Dam Access
Access to the tunnel portal and the damsite would be by helicopter. 'Other
means such as roads and tramways were considered but found .infeasible or
too costly.
Bui ldinas, Grounds, and Util ities
---'-----' .
The camp would provide quarters and offites during const~uction ~nd
permanent maintenance facilities during operation of the project. Included
in the camp would be permanent. facilities consisting of dock and seaplane
float, dormitory for four men, a residence for one family. warehouse,
garage, and sewer and water systems. .
FISH AND WILDLIFE MITIBATION
[he spawnihgimpulsein sockeyes found in Mahoney Lake is apparently
triggered by the temperature of water upwelling from grd~els of the Upper
Mahoney Creek delta. Most of this flow, which comes from the upper lake,
would be diverted through the power plant and returned into the upper creek
regime by an unlined tailrace channel, which would intersect the upper
creek about 500 feet upstream of the lake~ Returning the flow to the
stream is expected to maintain the upwelling effect. However, water drawn
from the upper lake would be colder than the normal surface flows and could
affect spawning and proper egg development.
To maintain tolerable water temperatures at points of ~pwelling during the
critical spawning and incubation periods, warmer water would be pumped from
the lower lake and mixed with tailrace waters. An l8,000-gallon-per-minute
(40-cfs) pump would be placed at the lower lake approximately 1,500 feet
from the powerhouse, with the intake being sJfficiently distant from the
spawning area. A 24-inch steel pipeline would discharge the warmer water
at the tailrace stilling basin where it would mix with the 4°C water from
the upper lake. Instrumentation would be installed to record temperatures
in the spawning area and a monitoring program would be established for
quality control.
Alternative measures to maintain suitable temperatures of the tailrace
water were considered. The most feasible method identified was to control
the intake temperature at the upper lake by means of a multi-level or a
floating intake that would draw the warmer surface water. High costs and
ice problems made these alternatives infeasible.
COST ESTI~1ATES
All estimates are based on October 1982 price levels. The contingency used
for all alternatives was 20 percent. Engineering, design, and supervision
and administration costs are each 8 percent of construction costs. The
construction time was estimated to take 4 years with a power-an-line date
of 1989. Mahoney Lakes project costs are shown in the following tables.
f),.. 1 1
Table 0-1
Mahoney Lakes Project Summary Cost Estimates 1/
Item.
Mobil i zat i on and Preparatory Work
Lands ~nd Damages
Reservoir
Uam
Intake Works
Penstock
Power Plant
Powerhouse
Turbines and Generators
Accessory Electrical Equipment
Accessory Systems and Equipment
Switchyard
Transmission Line
Beaver Falls Substation Modifications
Roads and Bridges
Buildings, Grounds, and Utilities·
Heliport
Mitigation
Subtota 1
Contingenci~s (20%)
Subtotal
Engineering and Design (8%)
Supervision and Administration (8%)
First Cost
l/All price levels based on October 1982 prices.
D-12
Total Cost
($1,000)
$ 2,200
66
85
1 ,513
1,079
11,437
1,362
4,608 .
1,267
761
712
1, 1 32
113
786
1,139
2,026
597
31,383
6,277
37,660
3,013
3,254
$ 43,927
Table D-2
Mahoney Lakes Project, Detailed Cost Estimates .Y
Item
Total -Mob and Prep Work
Lands and Damages
Reservoir
Public Domain
Powerhouse and Camp Site
Private lJomain·
Access Road
Private Domain
Transmission Facilities
Public Domain
Private
Total -Lands and Damages
Reservoir
Clearing
Dam
Total -Reservoir
Bin Construction
Galvanized Metal Bins
Rockfill for Bins
Rock Excavation
Concrete
Rockf i 11
Steel Plate Darn Face
Chain Link Fence Fabric
Rock Bolts (3/4" x 6')
Total Dam
Intake Chamber
Excavation
Concrete
I~ei nforcement
Rock Bolts (1"x7')
Drilling (14"¢ holes 9 ea)
Drilling (12"¢ holes 9 ea)
Pipe (12")
Pipe (14 II )
Gate Valves (1411)
Reduc ing Cone
St iffeners
. LS
AC
AC
AC
AC
AC
AC
95
4
8
45
5
10
L8 297,000
CY 5,000
CY 1,900
CY 100
CY 150
TON 23
SY 3,000
LF 1,260
Cy
CY
LB
LF
l_F
LF
LF
LF
EA
LB
LB
D-13
1,070
65
3,700
490
54
360
540
90
9
16,450
8,000
Unit
Cost
ill
8,500
2
78
70
1,130
70
4,950
35
42
Tota 1
Cost
($1,000)
$ 2,200
Permit
o
8
48
4 --66
85 ---as
594
390
133
113
11
114
105
53
1,513
318 $ 340
1,415 92
1 4
42 2~
340 18
312 \12
5630
70 6
14,150 127
4 66
4.25 34
Table O~2 (cont)
Item
Pipe (14 U w/18ea45°)
811 Drilled Vert Hole
811 Steel Vent Pipe
. 36" Remote Control
Spherical Valve
Total -Intake Chamber
Penstock
Tunnel Excavation
Rock Bolts (1Ilx8 i )
PenstockStee 1 .
Ring Stiffeners(Expansion~
·J\rchors, Anchor' Supports)
Concrete Anchor Blocks
Concrete Support ~iers
Tunnel Portal and Discharge
Road Excavation
Concrete
Rei nforcement
Rock Bolts (1Ilx7')
Chain Link Fence
Total -Penstock
Powerhouse
Excavation and Concrete
Building Superstructure
Misc. Building Items
Trifurcat i on
Branch Pipe
Valves
Total -Powerhouse
Turbines and Generators (3 ~nits)
Turbines
Generators and Excitation
. Equ i pment
Unit
Cost
Unit ~/ Quant 111
LF 108 . 140
LF 410 170
LF 30 50
EA 1 141,500
cv 13,240 311
LF 1,600 42
. LB 1,875,350 3
.. LB 131,300 3.20
CV 50 1,275
CV 190 1,275
CV 24,000 35
CV 20 1,415
LB 2,000 2
LF 350 42
SV 400 33
Governor and Cooling System
Total -Turbines and Generators
Accessory Electrical Equipment
Switchgear, Breaker,
and Busses
Station Service Unit
Supervisory Control System
Misc. Electrical Systems
Total -Accessory Electrical Equipment
D-14
Tota 1
Cost
($1,000 )
15
70
2
142
1,079
4,118
67
5,626
420
64
242
840
28
4
15
13
11,431
793
262
344
76
137
250
1,862
1,535
2,453
620
4,608
688
132
1 S 1
296
1,267
Table 0-2 (cont)
Item Un it 2/ . Quant
Auxiliary Systems and Equipment
H~ating and Ventilating
Station,i3rake, and
Governor Air
. Unwatering and Drainage
Systems
Overhead Crane
Misc. MechanicalSy~t~ms
Total -Auxiliary Systems and Equipment
Switchyard
Excavation and Grading
Power Transformer .
. Disconnect~ and Electrical
Equipment
Total -Switchyard
Transmission Line
(Without Access R.oad)
Clearing
I)eadend Structures
Tangent Structures
llround Conductor
Line Conductors
Total -Transmission Li~e
AC
EA
EA
MILE.
MILE
~eaver Falls SUbstation Modifications
Site Work LS
Support Structure, Switches,
Conduit and Controls LS
Total -Substation Modifications
Total -Power Plant (3-Unit Plant)
Roads and Bridges (Beach to
Powerhouse,. 16' wide, 7,153
Excavation (Rock)
F ill ( From E x c a vat ion)
Culverts (24" CMP)
Bridge (16'x50')
Clearing
Total -Roads and Bridges
Buildings; Grounds, and Utilities
(Without Access Road From
i3 e a v e Y' Fa 1 1 s )
LF)
CY
CY
LF
EA
AC
Timber Dock (30'x250') LS
Seaplane Float (30'x60') LS
Dormi tory (1,000 SF, 4 Man) LS
O 1 r -1::1
44
30
56
5
5
13.545
13,335
600
2
6
. Unit
Cost
ilL
8,490
8,490
5,940
6,790
27 , 170
35
1.4
50
106,000
~3, 500
Total
Cost
($1 , 000)
173
64
122
184
218
761
61
5/5
374
25)
333
34
135
') " 0:
85 -T13
10,455
47[1
19
30
212
51 -78"6
3~;4
9~
i06
Table 0-2 (cont)
Item Unit 1:../ Quant
Residence (l,OOQSF)' . LS· 1
Warehouse & Garage (3000 SF) ·LS· 1
Water System . LS 1 .
Sewer System LS . . 1
Total -Building~, ,Gfounds, ~nd Utilities, .
Heliport, Portal andOam Helipads
.. Foundation Prep~ration
Excavat i on, Rock' .
Concrete (Helipad)
Reinforcing St~~l
Total -Heliport
Mitigation
Pump (18,000 GPM)
Pumphouse (12'x25')
Electrical Supply
Piping (30" Uia., 1510 LF)
Pipe Support (20' centers)
Intake Structure '
Total -Mitigation
Subtotal
Contingencies (20"k)·
Subtota -I
Sy
,Cy
Cy
TON
LS
LS
LS
LS
LS
LS
Engineering and Design (8%)
Supervision and Administration (8%)
Total -First Cost
4,500
41,980
375
14
1
1
1
1
1
1
1/ All prices based on October 1982 price levels.
Unit
Cost
ill
5
35
1,275
4,000
Tota 1
Cost
ill, 000)
106
425
14
42
_LJ39
23
1,469
478
56
2,017
100
70
49
277
60
41
597
31,383
6,277
37,660
3,013
3,254
. $43,927
2/ LS = lump sum, AC = acre, LB = pound, SY = square yard, LF = linear
feet, EA = each, and. 'CY = cubic yard. .
U-16
APPENDIX E
LAKE GRACE PROJECT PLAN DESCRIPTION AND COST ESTIMATES
APPEI~D I X E
LAKE GRACE PROJECT PLAN DESCRIPTION AND COST ESTIMATES
PROJECT DESCRIPTION
Lake Grace is on the east side of Revillagigedo Island, approximately 28
miles no~theast of KetChikan (Figure E-l). The outlet of Lake Grace is
Grace Creek, which flows east into Behm Canal.
The Lake Grace project would be a controlled reservoir water source Nith
major project features being a thin arch concrete dam, an intake structure
at the normal lake surface elevation, which would feed into an underground
power tunnel with an incorporated surge tank, a surface steel p€nstock, and
powerhouse with two 10,000-kW generators (Figure E-2).
The major portion of the nonoverflow dam would be a double curvature thin
arch with a maximum height of 156 feet (Figure E-3). The top of the dam
would be at elevation 516 feet. The remainder of the nonoverflow sections
and the spillway would he concrete gravity structures. The ungated spillway
would be 100 feet long with a crest elevation at 500 feet. This spillway
would have a peak design capacity of 11,600 cfs that would discharge onto a
rock chute excavated at the toe of the dam, then into the creek.
The emergency outlet works would consist of two 4-by 4-foot vertical lift
slide gates set in tandem with the invert at elevation 419 feet. These
gates would give the capahility of 90 percent reservoir drawdown in 4
months.
The intake structure would be located approximately 40 feet upstream of the
dam with the invert at elevation 411 feet. Intake regulation would be by a
7-by ll-foot fixed wheel vertical lift gate. An emergency fixed wheel
bulkhead would be located upstream from the regulating gate. The
regulating gate and emergency bulkhead would be hydraulically controlled.
The topoyraphy around Lake Grace is such that the most economical access to
the lake from the powerhouse would he by the excavation of a power tunnel
through a rock ridge east of the lake. The power tunnel would be a
modified horseshoe 10 feet wide and 10 feet high and approximately 3,400
feet long. From preliminary investigations, the rock that would encase the
power tunnel appears sound, so that about 20 percent of th~ tunnel's length
would require concrete lining. The underground surge tank would be 18 feet
in diameter, rising approximately 185 feet above the power tunnel and
opening vertically to the ground surface. A horizontal tunnel or drift
would connect the surge tank to the power tunnel. The penstock would
emerge from a concrete plug in the surge tank chamber through a steel
reducer. The all welded penstock would be 7.5 feet in diameter, 1,000 feet
long, and supported on concrete piers. The penstock would extend
approximately 200 feet from the surge tank chamher through an open tunnel
on a 1 percent slope to the portal and continue the remaining 800 feet to
the aboveground power plant. The portion that would lie between the tunnel
portal and powerhouse would plunge down a steep hillside and bifurcate ar
the powerhouse. Each penstock would have a shutoff valve in the valve room.
-.. 11111011
,
f
,
... o
• ... ......
LOCATION MAP
/
/
LAKE GRACE
LOCATION MAP
Figure:
E-1 --_ .......... eMfY ..... ", ••• L~ ___ .n_
PLAN
RQOO' 4000' ::E::: I
.,.,.
........... 7.-
f _ .....
... -
LAKE GRACE
PROF]I f , . .. ...
--------~ ... -
_"-L~ '"
-_11)1 0 -----
,.
--0.
_1_""'-
,
SECTION 0
" ---{E) \+ \
I , ,
I
.erg 0
• ! ... ,..n. ,
LAKE GRACE
COIK_TI ._TV AND ARCH DAM 1Ct_
Figure:
E-3 . --_ ...... .,._ ... rUd II ..........
The Lake Grace power plant would be located on Grace Creek approximately 1
mile upstream from its mouth. The centerline of the bifu~cation would be
at an elevation of 30 feet. The powerhouse would contain two 6.9-kV,
10,000-kW, three-phase synchronous generators. Each generator would be
driven by a 13,810-hp vertical Francis turbine~ with a rotational speed of
514 rpm at a design head of 450 feet. Dependable capacity would be 19,500
kW, with firm annual energy of 102,500 MWh, and average annual energy of
108,600 MWh at60 percent ·plant factor. Remote control of the power plant
would be from Ward Cove and would be accom~lished through the use of a
carrier communications system. The transmission line would run
approximately 2G miles to the Carroll Inlet intertie.
COST ESTIMATES·
. Detailed ~ost estimates of the Lake Grace project are given in Table E-l.
All estimates are based on October 1982 price levels. The total construc-
tiori cost includes a cbntingency Of 20 percent and engineering, design,
supervision, and administration costs.of 8 percent each. The construction
time of the Lake Gra~e project was estimated to take 4 years with
power-on-lihe in date 1989.
Table E-l
Lake Grace Hydropower Project Detailed Cost Estimates 1/
Unit lata 1
Cost Cost
Item Unit '£/ Quant ill ill, 000)
~~ob and Prep Work LS $ 5,519
Lands and Damages
Government Admin. Cost LS 57
Reservoir
Public Domain AC 4,960 3,178
Powerhouse and Camp Site
Public Domain AC 4 6
Access Road
Public Domain AC 36 35
Transmission Facilities
Public Domain AC 365 545
Tota 1 -Lands and Damages ·-3,821
Reservoir
Clearing AC 910 5,000 6,439
Total -Reservoir -6,439
Dam
Rock Excavation CY 8,500 57 485
Common Excavation CY 1,200 14 17
Drilling and Grouting LF 5,200 85 442 .
Drain Holes LF 2,600 64 166
Concrete Mass CY 22,400 142 3,182
Concrete Structural CY 100 849 85
E-5
Item
Cement
Reinforcing Steel
Gates (Outlet Works)
(2 ea 41 x4 I) 17,000#
Trashrack 4,000#
Total -Dam
Spi llway
Rock Excavation
Common Excavation
Drilling and Grouting
. Drain Holes
Concrete Mass
Concrete Structural
Cement
Reinforcement
Total -Spillway
Power Intake Works
Rock Excavation
Common Excavation
Concrete Mass
Concrete Structural
Cement
Reinforcement
Gates Wheel Mounted
7 l xll ' (52,500 LB)
71x14 1 (45,500 LB)
Trashrack 48,000#
Access l3ridge
Rock Excavat i on
Common Excavation
Embankment (Select)
Concrete
Reinforcement
Miscellaneous Metal
Table E-l (cont)
Un it ~/ Quant
CWT 72,700
LB 544,200
LS 1
LS
CY 4,000
CY 700
LF 1,000
LF 500
CY 3,350
CY 420
on 12,570
LB 27,700
CY 3,370
CY -I , 120
CY 3,470
CY 1 ,920
CY 21,170
CY 209,700
EA
E,L\
EA
CY 34
CY 34
CY 22
CY 100
LB 5,550
LB 2,000
Total -Power Intake Works
Power Tunnel (3,400 1 10'xlO'Horseshoe)
Rock Excavation CY
Concrete
Tunnel Lining 11 (700 LF) CY
Cement CWT
Reinforcement LB
Rock Bolts (l"xlO ') LF
Total -Power Tunnel
E-6
14,300
880
4,960
69,600
3,600
Unit
Cost
ill
11
1
57
14
85
64
142
708
n
1
57
14
142
600
11
1
100
21
28
960
1
5
278
708
1 1
1
42
Tota 1
Cost
($1,000)
802
544
85
11
5,819
228
10
85
32
476
298
138
28
1,295
192
16
493
1,158
233
210
425
425
142
3
1
96
6
10
-3,411
3,542
624
57
70
151
-4,444
Tahle E-l (cant)
.. 'Item
Penstock (7-1J2'xl,OOO LF)
Steel (A537) U3 595,000
Steel (A-36) Ring
Stiffeners
Exp Anchors, Ancho~
Supports, Etc.
Contrete Anchor Blocks EA 3
(20 CY) .
Concrete S~pports (9 CV EA)
Cernent
EA 18
CWT 8.30
Reinforcement LB 4,400
Clearing (30') AC .6
Total -Penstock
Surge Tank and Connecting Tunnel
Excavation
S lJ 1"g eTa n k 1 8 ' ( 1 70' ) C Y
Tunnel 10' (10') CY
Concrete Liner CY
Cement CWT
700#
LB
LF
EA
Rei nforcelilent
Rock Bolts
Steel Orifice
Total -Surge Tank and Connecting Tunnel
Construction Facilities
Cofferdams
Excavation Common CY
Embankment CY
Diversion Works Tunnel
(15'x310'horseshoe)
Excavation Rock CY
Rock Bolts LF
Concrete Tunnel Liner CY
keinforcement LB
Cement CWT
Tempol'dr'Y Closure (Porta 1 )
Excavation Rock CY
Concrete CY
Reinforcement LB
Steel Bulkhead (10,900#) EA
Ceillent CWT
Tunnel P-Iug Concrete CY
~iscellaneous Metal LB
Cement CWT
Total -Construction Facilities
E-7
1,600
30
85
480
8,500
1,500
1
970
4,770
2,330
1,500
61
5,300
400
50
48
3,800
1
230
{50
2,000
750
unit
Cost
ill
3.20
2.80
11,000
6,390
11
1
1,400
28:3
240
920
11
1
42
14
21
279
42
920
I
11
85
990
1
11
566
6
11
Tota 1
Cost
($1,000)
1,898
117
33
115
9
4
8
~184
452
7
78
6
9
64
4
n20
14
102
649
64
5
4
4
48
4
35
3
142
1)
8
~1'-.-"1-;=-5 6
. Table E-l (cont)
Item
~)owerhouse
Excavation RocY:
Concrete Structural
Concrete Mass
(Wye Encasement)
Cement
Reinforcement
Structural Steel-
Mise Metal'
DrCift Tube Li ner,·.
Crane Rail & Acte$ciries
Draft Tube Bulkhead
ann Guides
Wye branch:
Spherical Valves
Heating and Ventilate
Generator and Turbine
Cooling
Potable Water
I~aw \~ater
Sewer
Mise Electrical & Lighting
Miscellaneous
Architectural Features
Total -Powerhouse
Turbines and Generators
Un it ,{I Quant
CY 6,500
CY 2,690
. CY 800
CY 18,300
LB 295,900
LB . 94,800
. LB 20,000
LB 14,400
LB iQ,OOO
LS 1
LS 1
EA 2
LS 1
LS 1
LS 1
LS 1
LS 1
LS 1
LS 1
LS 1
Turbine Vertical EA 2
Francis (13,810 hp)
Generator (10 MW) EA
Governor EA
Total -Turbines and Generators
Acces sory E 1 ec t ri c al Equ i pment
Generator
Switchgear (7.2 KV
4 e a, 1, 200 AMP)
Conduit and Wiring
Neutral Grounding
Equipment
480 V Station Servic~
Grounding System
Supervisory Controls
DC Control Batteries
Charger, Inverter, Etc.
LS
LS
LS
lS
LS
LS
LS
AC and DC Panelboards LS
Generator LS
Total -Accessory Elettrical Equipment
E-8
2
2
1
1
1
1
Unit
Cost
ill
57
708
425
1 1
1
3.50
4.95
3.90
3.90
389,000
1,033,000
I, 111 ,000
241,000
Total
Cost
($1,000)
368
1,905
340
207
296
332
99
56
39
99
142
778
191
64
14
35
35
99
191
283
5,573
2,066
2,222
482
4,770
389
85
42
127
35
127
57
16
35
913
Table E-l (cont)
Item Unit '{I Quant
Miscel~aneous power Plant Equipment
35-Ton Bridge Crane EA
Watering and Unwatertng
System LS, 1
Drainage SY,stem LS 1
Lube Oil LS 1
Fire Protection ~nd Oetk
W~sh LS
C02 Fire Protection System LS 1
Statinh Air LS 1
Bra~e Air LS 1
Governor Air LS 1
Piezornete~ & Float Well LS 1
Oil Purifier LS 1
Shop Equipment LS 1
Total -Misceflanecius Power Plant Equipment
Tailrace
Excavat i on Rock
Riprap
lotal -Tailrace
Swi tchyard
Power Transformer
GrolJndmat, Disconnect
Switch and Ground
Switch Bus
Surge Arrestors
Excavation Rock
Takeoff Tower
Total -Switchyard
Transmission System
Carrol Inlet Intertie (115 kV)
Site Preparation
Equipment
Switchgear & Switchyard
Carrier Communications
Equipment
Transmission Line, Lake Grace
P.H. to Ward Cove (20 miles)
H-Frame Pole Line
Structures
Connuctor (397.5 MCN)
ACSk (3 conductors)
Clearing (150' wide)
Total ~ Transmission System
Cy
Cy
Cy
Li)
LS
LS
LS
EA
MI
AC
E-9
1, -180
300
1
4
4,600
29,000
1
164
20
365
Unit
Cost'
ill
57
,28
5,660
57
3.20
14,000
49,500
5,660
Tota 1
Cost'
ill,OOOl
196
50
64
35
14
50
50
6
'14
14
50
64
--607
67
8
75
282
21
23
260
93
679
71
309
212
2,296
990
2,066
5,944
Table E-l (cont)
Item Un i t 1:./ Quant
. Total -Power Pla~t
Roads and Bridges
Clearing
Rock Excavat ion
Common Excavation
Embankment
Gravel Road Surface
Culverts
Single Lane Bridge
( 100 LF long)
Total -Roads and Bridges
Buildings, Grounds, and Utilities
Timber Dock (30'x250')
Seaplane Floating Dock
(30'x60')
Dormitory (1,500 SF) .
Residence (1,000 SF)
Warehouse. and Garage
At
CY
LF
.LS
LS
LS
LS
LS
LS
LS
34
14,630
41,540
60,230
9,340
740
1
1 .
1
(3,000 SF)
Water System
Sewer System
Total -Buildings, Grounds, and
LS
Utilities
SlJbtota 1
Contingencies (20%)
Suhtota 1
Engineering and Design (8%)
Supervision and Administration (8%)
Total -First Cost
1/ Based on October 1982 price levels.
Unit
Cost
ill
8,490
42
7
3
28
70 .
. Tot a 1
Cost
($1,000)
18,560
289
621
294
170
265
52
354
2,045
495
142
163
106
. 425
14
42
1,387
56,701
11,340
68,042
5,443
5,443
$78,928
II LS = lump sum, AC = acre,lF= linear feet, CY = cubic yard,CWT =
~undred weight, LB = pound, EA = each, and MI = mile.
E-10
APPENDIX F
OPERATION, MAINTENANCE, AND REPLACEMENT PLANS ANlJ COSTS
APPENDIX F
OPE~ATION, MAINTENANCE, AND kEPLACEMENT PLANS AND COSTS
I NTRODUCT ION
~urpose and Scope
This a~pendix presents estimates of operation, maintenance, and
replacement costs for Mahoney Lake and Lake Grace, which are two
potential hydroelectric projects near Ketchikan, Alaska. The appendix
was originally 3 report that was initially prepared by the U.S.
Department of Energy, Alaska Power Administration (APA), as input to the
Corps of Engineers feasibility investigations of alterrative
hydroelectric projects in the Ketchikan al"ea and as part of the Corps'
Southeast Alaska hydroelectric studies conducted under a 1970 U.S. House
of Representatives study resolution. Requirements that will affect
project designs and cost estimates are also presented in this appendix.
Previous Studies
Two previ !Jus Y'eports were preparefJ on t,le vari ous projects:
Lake Grace Project, Alaska, January 1968, Alaska Power
Adnli l1i strat i on.
Swan Lake, Lake Grace, and Mdhoney Lake Hydroelectric Projects,
Appraisal Report, June 1977, R.It.i. Be-ck and Associates.
~TUDY A~SUMPTIUNS AND METHODS
The analyses assume an operation plan that is substantially similar to
the [\PA"s Snettisham project near Juneau. fl,laska. The key assumptions
involve:
1. Project operations hy Ketchikan Public Utilities (KPU) are made by
supervisory control from a centralized operations control center in
Ketchikan. Incremental costs to KPU are included as lump-sum
estimates.
2. Project maintenance is to be performed by Federal maintenance
operators assigned to the projects an~ supplemented by KPU
Illaintenance personnel. These inriividuals would o;Jerate the project
under emergency situations.
3. It rnay l)e des i rab I e to use pre-progY'Binrned rni ni -computors for rout i ne
operation. This would minimize the work load for operating
personnel. Manual override capability would be provided at the KPU
operations center Jnd the power plant.
4. Uvp.r.::ll project adillirllstration, including power sales contracts,
Dilling, accounting, and annual inspecti0ns would be provided by the
APA headquarters office in Juneau, A1aska.
5. Technical services such as electronics systems maintenance and
repair, meter relay mechanics, and staff for major maintenance
activities would be provided on an as-needed basis byKPU personnel
supplemented by APA headquarters and the Eklutna and Snettisham
hydroelectric projects. This amounts to sharing the skills of the
staffs of several small projects to minimize total operation and
maintenance costs.
6. Transmission line maintenance and major power plant maintenance such
~s turbine overhaul would require additional manpower. This could
be provided either by. KPU st~ff or detail of personnel from other
APA projects. The Federal maintenance operators could do routine
transmission line inspection and assist in repairs.
It is believed that SUCh a plan would minimize costs to area power
consumers and provi de appropri ate 1 eve 1 s of maintenance.
The study approach involved a fairly detailed estimate of operation,
maintenance, and repair requirements for the Mahoney Lakes project. The
Lake Grace estimates 0ere developed as modifications of the Mahoney Lake
estimates. The main differences involve the extent of the facilities to
be maintained and the relative remoteness of the project, which, in turn,
shows up in different staffing requirements and transportation and
material costs.
The estimates are based on December 1977 price levels with wage costs
based on APA wage schedules for Snettisham project personnel for June
1977 to June 1978 (updated to October 1982 price levels hythe Corps of
Engineers).
The operation and maintenance plans assume that the following features
will be included in the Corps' design and cost estimates:
1. Adequate warehouse space for vehicles, snow removal equipment,
supplies and materials.
2. Supervisory control equipment for installation at the KPU operations
center and a carrier communication system between the plant and the
operations center. Installation of multiple mini-computers with
manual override ~apability for scheduling and controlling power
operations. .
3. An adequate voice communication system of either telephone line,
microwave and/or radio between the plant and the operations~enter
in addition to the carrier system. .
4. Vehicles and equipment that are listed in the operation and
maintenance estimates.
5. Living quarters for personnel assigned to the project: provisions
for housing up to eight people on temporary assignment for major
maintenance and emergency situations, located c"lose to trle power
plant to minimize snow removal and generally to facilitate
maintenance work.
F-2
6. Water, sewer, and electrical systems at the project site.
ANALYSIS
The analysis includes itemized costs for personnel, miterial, and
equipment for the Mahoney Lake and Lake Grace projects.
The ave,'age annual cost of pickups, trucks, and other equjprnent was based
on trle total cost ov.er the life of the equipmenLll By trading equipment
before the end of its service life, some salvage value would be recovered,
so the equipment requirements and annual cost shoul~ be about the same.
Annual replacement factors (based on 8ureau of Reclamation experience)
are given and the~nnual r~placement costs are calculated in Table F-l.
The annual replacement costs provide for a fund to finance major items
that have a life period Df less than 50 years for project repayment. It
is normal Federal practice to set power rates sufficiently high to
provide a fund for replaceable items, such as generator windings and
accessory eleCtric equipment, when they become due. Many project
features don't require repl~c~nent within the laO-year project life, such
as the dams and concrete power plant structure. Therefore, these costs
are not included among the reulaceable items. The analysis on Table F"-l
uses sinking fund factors for the portions of the power plani,
transmission line, and substation, which have lives less than 100 years.
Table F-l
Anllual Replacement Costs for ~·1ahoney Lab: and Lake Grace Projects
Mahoney Lake
Cost of Annu~l
keplaceable Replaceable
Fea tuy'e Items Cost ---
Power Pl ant $ 9,171 > 600 $ 10,850
Switctlyard 571,900 2,050
Transmission Line 2,711,700 _____ ~,700
Total $ 15,600
Cost of
Replaceable
Items
$17,295,000
958,200
30,395,000
Grace
Annual
Replaceable
Cost
$ 20,950
3,6')()
30,600
$ 55,200
Constructi6n costs are on January 1977 price level (updated to October 1982
by Corps of Engineers, using the Engineer News Record Construction Cost
Index). Manoney Lake costs were furnished by the Corps of Engin~ers in
July 1977. The Lake Grace costs are ft'orn the 1976 Corps of Engi neers
estimate revised August 1977 and indexed from January 1976 to Llanuar'Y 1977,
usiny the Engineer News Record Construction Cost Index.
-----------
11 During review, KPU personnel indicated they use shorter service life
estimates than assumed in the APA studies.
F-3
The development of costs for operation and maintenance of the project
assumes no road access from Ketchi kan. Access for project construction,
operation, and maintenance would be by water and air to a dock in th~ b~y
below Mahoney Lake.· A l-mile road would conn~ct th~ airplane float and
boat dock to the power plant. Facilities would include:
1. A pennanent boat and barge dock for use during construction and
later use during project operation.l!
2. Phone communications and adequate security for fuel storage
faciities at the dock.
3. A wafehouse for vehicles, supplies, and materials.
4. Living quarters for three operations and maintenance personnel and
visiting maintenance men. A total of three maintenance men would be
required for equipment maintenance and safety. Their duties would
include operation of heavy equipment, plowing snow, and road
maintenance between. the powef plant and dock, caring for the
warehouse and its stores, and maintaining the living quarters for
the remote site.
Expenses for two airplane fli~hts per week between Ketchikan and the dock
near the power plant are included. Transmission llne inspection and
maintenance would be by local chartered helicopters. The i-Jork would bp
done by contract arrangement with KPU or APA personnel.
A detailed list of personnel, equipment, supplies, and administrative
costs for Mahoney Lake is presented on Table F-2.
l! During review of the draft operations and maintenance plan, KPU
suggested a grid of permanent pilings to support and stabilize a
barge during loading and unloading operations.
F-4
Tab 1 e F -2 .
Mahoney Lake Project Operation and 1\1aintenance Costs
Personnel
Operatlon:
KPU 0peration time for monitoring te:~~eter control
syst~rn, alarms, etc., and provision f()r emergency
oper'ation of the POWel" plane (lump-sunl)
IVJa i ntenanc:e: .
I foreman at power plant, $24.00/hr x 2,080 hr!yr
;.: rnen at power plant, $22.00/hr x 2.080 hr/y\"
Specialists, elect~onic technicians, meter relay
Inechanics, etc., 1 week/rno at $22.0iJ/hr
Per diem for out-of~town maintenanc2 ~ersonc
Holidays--ll/yr x 1 ~an x $22.00/hr x 8 hr/d~y
x 1-1/2 extra pay
Overtime--200 hr/yr x $22.0Djhr
Vacation--(inc1uded in salaries above)
Suhtotal Meintenance
Contribution, 9% of wages
Subtotal for operation and ~~intena~ce personnel
Mi scel] aneous
---snlPPlng
Telephone
Travel (including flights to power plant)
Vacation Travel
Supplies, Service, and Materials -(power plant)
Employee Training
Sup~lies and Services -(movab1e equipment)
Subtotal
Transmission Line Maintenance
$2,800jml x 4 mi plus 1"2,800/hel icoqter
.Equipment
Pickup
Truck
f{Oad Grader
~ackhoe with Bucket
Front-end Loader with
Snowblower
Small Truck-r~()unte(j
Crane
Subtotal
No.
I
1
1
Cust
" -ii "j 1,200
35,400
70,800
49,500
106, 100
F-S
Service
Life
--,----
7
10
15
15
10
AnnllJ 1
Cost
$ !,,600
3,500
4,700
3,300
10,800
4,.I'JO
23,600
Costs
$ 15,OG02/
:0,050
90,960
10,500
2,830
2,890
4,370
1,40n
!,4GO
32,300
1 ,/l00
7,200
noD
2,300
$ 4/,300
14,OUO
pre "/(1 . Ll:S, llUj
APA Headquarters
8i111n9s, Reports, Contract Administration
and Project Su~ervision
Summary
Personnel
Miscellaneous
Transmission 1.ine Maintenance
Equipment
APA Contract Admi nistration
Subtotal
Unlisted Items & Contingencies (2~1o)
Total
~j Includes $15,000 cont~act services from the local utility.
$ -35,300
190,9001/
47,300-
14,000
28,600
35,300
3i6, 100
63,200
~-
-?"'J 379,3:)0
Personnel costs are based on preva11ing wages effective between June
1977 and June 1978. Equipment costs are based on January 1978 prices.
(Personnel and equipment costs updateo to October 1982 levels by the
Corps of Engineers.)
Gecause of the increased distanc~ from Ketchikan and the additional power
plant and dam features to be tended, one extra APA maintenance man probably
would be needed at the Lake Grace project, fora total of four. There
would also be an increase in the necessary supplies, services, and
equipment for maintaining their life support systems. More equipment would
he needed for snow ~emoval and maintenance of local project roads. The
longer transmission line would require additional costs for helicopter time
inspection, maintenance, and emergency repairs.
The analysis presented in Table F-3 inclu(]es the Lake Grace itemized costs
for personnel, materials, and equipment.
F-6
Table F-3
Lake Grace Project Operation and Maintenance Costs
Personnel
upel' at ion:
KPU oper2.tion time for monitoring telemeter control
system, alanns, etc., and pr6vision for e~etgency
6peration of the power plant {lump-sum}
f~a i ntenance:
Powerp 1 ant foreman , $24.00/ht x 2,080 hr /yr
3 men at power plant, $22.00/hr x 2,080 hr!yr
Specialists, elect~onic techniclans, meter relay
mechanics, etc., 1 week/rna at $22.00/hr
Per diem for out-of-town mai.ntenance persons
j101idays--ll/yr xl man x $22.00/hr x 8 hr/day
x 1-1/2 extra pay
Overt irne-·-200 hr /yr x $22.00/hr
Vacation--included in 2,080 hr/yr above
Subtotal Maintenance
Contribution
Subtotal for operation Jnd maiGtenance personnel
IYJi see 11 aneous
~l-ipplng
Telephone
Travel (including flights to power plant)
Vacation Travel
Supplies, Service, and Materials (power plant)
Enlp 1 oyee Tra in i ng
Supplies and Services (movable equipment)
Subtotal
Transmission Line Maintenance
--support Hellcopter (repairs and monthly)
Linernen--10 days x 8 hr/day x $22.00/tlr x 2 men
Miscellaneous Spray Material, Repair Parts,
Clearing, Small Tools, Per Diem, etc.
Subtotal
Service
Pickup
Tr'lAck
Road Grader
i)ackhoe wi th Bucket
Small Truck Mounted
Crane
Front-enn Loader with
Snowb 1 O'.ver
lW 11 dozer (D-3)
Suototal
No. Cost Life
$ 11 , 300 7
35,400 10
70,800 15
49,500 15
46,700 10
106,100 10
140,UOO 10
-----459 ~·800
F--7
Annual
Cost
$ 1,600
3,500
4,700
3,300
4,700
10,800
14,000
42,600
Costs
$ 21, OOO_U
50,050
136,460
10,500
2,830
2,890
4,370
228, 100
20,500
_. 248~6GO
2,500
1,400
32,800
2,500
14,000
1,200
14,000
68,400
26,200
3,500
35,400
$b5,100
$ 42,600
API'" Headqua rters
Billings, Reports, Contract Administration
and Project Supervision
Summary
Personnel
Iv] i see 11 aneous
Transmission Line Maintenance
Equipment
APA Contract Administration
Subtotal
Unlisted Items & Contingencies (2rn~)
Tota 1
$ 35,300
248,600
68,400
65, 100
42,600
35,300
460,000
92,000
$ 552,000
!f Includes $35,300 ~ontract services from the local utility,
Personnel costs ~re based on prevailing wages effective between June
1977 and June 1978. Equipment costs are based on January 1978 prices.
(personnel and equipment costs updated to October 1982 levels by the
Corps of Engineers.)
RESULTS
A plan was developed and the follo~ing summary presents the incremental
cost to KPU and APA to accomplish this plan for each of the projects--
Mahoney Lake and Lake Grace.
===~==~=======,==== ===,
Table F-4
Annual Operation, Maintenance, and Replacement Costs Summary
O&M Replacement Total orV]&R
Cost Cost Cost
Project ($ ) ($ ) ($ )
IVJahoney Lake 379,300 15,600 394,900
Lake Groce 552,000 55,200 607,200
~-=-=:--'=---=-...:::::
The analyses are designed to show the incremental operation and maintenance
costs for adding a new hydropower project in the Ketchikan area. The two
plans assume power plant operations would be handled by KPU by supervisory
control from a central KPU dispatch center. Under this assumption, the
basic cost for the dispatch center would be in KUP's operating budget with
only the incremental operating cost assigned to the new project. We
believe this is an appropriate cost measure for use in feasibility
netennlnations and that this type of plan will result in the lowest total
power costs to area consumers.
F-8
APPENDIX G
LOAD FORECAST
hlc£/:-~
PART I!. POWER MARKET AREA
The power market area includ~s the KPU service area around ·Ketchikan.
Metlakatla was not included because it is assumed to have adequate near
term power supply with construction of the proposed Chester Lake project.
A potential long-term Ketchikan/Metlakatla connection may be desirable,
but is not significant to the Mahoney Lak~ analysis. The area is shown
on Fi gure 1.
Service Area arid Population
The KPU service area includes all of the developed area .in the Gateway
Borough around Ketchikan,. which includes Saxman and some outlying rural
area. The 1980 Borough population was 11,347. The City of Ketchikan
had a population of 7,248 accordi~g t6 the 1980 census. The Borough
population growth rate of 1.2 percent for 1970 to 1980 was somewhat less
than the statewide trend, but was a steady increase.
Economic Base and Employment
The economy of Ketchikan is based on manufacturing, retail trade,
services, and local government. One fifth of Ketchikan's work force is
directly involved in manufacturing industries--principally timber and
sea food processing. Retail trade employs 15 percent; services such as
L/
hotels, legal firms, and support businesses also employ 15 percent;
local government employs 14 percent. The remaining 36 per cent employment
is in State and Federal government, construction and transportation,
''1--'>~-~'.
~" " '.
G-2
GRACE
ITED STATES' : :, : ,,':: :-' UN " ,. ',:: '
ALASKA pg!=~RTMENT OF ENERGY"
ADMINISTRATION
PROJECT LOCATION
Figure 1
AP1\ 8/79
communication, and utilities. These statistics and distribution of
usage payments are presented on Tabl e 1.
Major futureempl oyers wi 11 conti nue to be timber and seafood, with a
strong possibility of·mining developing in the next few years. Timber
and seafood will grow steadily with cyclical fluctuations depending on
market conditions, and mining will be steady once online.
Timber
The Forest Service plans an annual long-term harvest of 227 million
board feet of timber which would be processed in the Ketchikan area.
This would be half the tOtal harvest of the Tongass National Forest.
The near-term outlook is poor until the timber· market economy improves.
The long-term outlook is good.
Timber harvest plans by Sealaska Corporation are for 1.50 to 200 million
board feet beginning in 1983 and continuing at that level for the long-
term. Eighty percent of the land involved will be on Prince of Wales
Island with most supporting services coming from Ketchikan.
G-3
TABLE 1. KETCHIKAN INDUSTRIES: EMPLOYMENT AND WAGES, 1979
Industry Percentage of Percentage of
Total Employment Tota 1 ~~age Payments
r1anufacturi ng 19.6% 28.0%
Reta i 1 15.3% 8.6%
Services 14.5% 9.9%
Local Government 13.8% 13.9%
Transportation, Communi-
cations and Utilities 11.1% 10.5%
State Government 8.3% 11.1%
Construction 5.3% 7.6%
Federal Government 5.0% 4.8%
Finance, Insurance,
and Real Estate 4.0% 3.2%
Wholesale 2.4% 2.7%
Total Employment and Wage
Payments 5,317 $105,149,000
Source: Statistical Quarterly, Alaska Department of Labor.
Excerpt from: Ketchikan Gateway Borough, Ketchikan, Alaska,
Waterfront Development/Management Study, Phase One,
Charles Pool & Associates, Inc., December 1980.
G-4
Fishing
The outlook of commercial fishing in Southeast Alaska is for a continued
stable industry without significant changes. The salmon and halibut
fishery are expected to remain stable; development of a few "fill-in"
markets is expected for specialized bottom fish species such as quality
rockfish and black cod; and development of a small trawl fishery is
likely. The geology of Southeast Alaska limits the shallower shelf
where bottom fish are found. A small trawl fishery consisting of one or
two boats exists at Petersburg; future trawl fishery in Ketchikan is
expected to be slightly larger. The outlook for energy needs by the
fishing industry is for stable use with only minor increases.
Mining
The proposed U.S. Borax molybdenum mine at Quartz Hill, 40 miles southeast
of Ketchikan, would be the single largest single-point electric power
load in Southeast Alaska. The company estimates power needed to be 62
MW at 80 percent plant factor--435 million kWh per year--with a 1987
start-up. Orebody reserves amount to more than a 100 year supply and
are discussed in terms of the largest molybdenum deposit in the world.
Designs f6r mining and service facilities at the site are not finalized,
but consideration is being given to housing employee families in Ketchikan
and providing only work camp facilities at the mine. One early estimate
is that 700 homes would be constructed in Ketchikan before 1984.
Additional schools and commercial and municipal services would be needed
at the same time.
G-5
Mine construction is expected to involve 1,000 workers from 1984 to
1986; 860 people will be needed for production operations beginning in
1987.
Construction is expected to have some effect on electric demands in
Ketchikan beginning in 1983 to 1984 due to support services. Housing in
Ketchikan for construction employees would begin in 1984, and increase
for the 860 permanent employees plus related commercial and community
support facilities beginning in 1987. Some estimators use the figure
that each basic job creates one additional job in the community for
service and support. The total effect then could be up to 1 7 720 new
jobs (new electric customers) by the time full employment exists.
G-6
PART III. EXISTING POWER SYSTEMS
The electric utility system for Ketchikan is a combined electric and
telephone utility system and is operated by the municipality. KPU has
been in operation s"ince 1935 and operates a combination of hydro and
diesel generation plans, a distribution system, and will operate the
State Swanlake Project which is under construction. Table 2 presents
the data on the existing diesel generation and hydropower facilities in
the Ketchikan area, totaling 28.8 MW and 78.7 GWh. The net average
annual generation from the hydro units shown is the expected annual
capability based on average water conditions. The diesel generation
annual energy show the maximum generated by each unit between 1970 and
1978.
Two timber industries, louisiana Pacific-Ketchikan (lPK) pulp company
and Ketchikan Spruce Mill each have their own installed generation
capacity--these total 38.6 MW and 150 million kl~h annual energy. Fuel
is primari ly wood by-products from the mi 11 s with oi 1 suppl ement. An
electricintertie between KPU and lPK is limited to 2 MW .. Since the
mill uses almost all of its sel f-generated energy and capacity, and the
interchange agreement is for rather small amounts of energy, the lPK
generation is not included in this project analysis.
Figure 2 shows the location of generating facilities and the local
transmission facilities.
G-7
TABLE 2. I<ETCHIr~AN PUBLIC UTILITIES POWER SOURCES
J-~e t ': hi k an
Lakes
Subtotal
Bea .... er·
Falls
Subtotal
Hydr·<.
Date Nameplate
InstallQd Capacity
[2J
192:3
19:;:8
1'357
.1947
1954
.1954
(KW)
al
1400
1400
.1400
4200
1200
2000
2000
5200
Silvis Lake .1968 2100
Swan Lake .1984 22,000
Totem Bi9ht
------------
Total 3:3,500
Total System Installed Capacity
H"rdro =
[liesl?l =
Intertie Capacity with LPK =
Total Capaci~y =
Total Net Generation (.198.1)
Hydro =
Di~sel =
Nl?t Interchangl? ~rom LPK =
Total Erlergy
N\~t Avq.
Ann. Gen. ---------
(t}WH)
17.1
37.4
.1..1.3
,~,5.4
======
.15.1.2
( MW )
33.5
16.5
2.0
52.0
( GWH )
71.7
14.4
7.4
~"J:3.5
Da t<? .
Installed ---------
.l:352
.1952
1952
1966
1970
1971
1977
[.1.] Ketchikan Lakes hy,oro 'capabi1ity r·educed in winter.
[2] Silvis Lake hydro oestroyed by mudslide in 1969;
rehabilitated in 1975; back on-line end o~ 1976.
[:~:] Baile,· plant rer·ated·~rom 4500 to 4000 kw irl 1978.
[4] Maximum ql?nerateo between 1970 & 1981.
[51 Ketchikan Lakes diesels retired in 1980.
Diesel
Nameplate
Capacity --------
(KW)
[5]
(279)
(315)
(279)
(873)
2000
(3]
4000
4000
6450
.14,450
------------
·16,450
Net An 11
Gen. l4] ---------
(GWH)
2.2
20.4
22.6
Alaska Power Administration 1.1-82
G-8
G)
.b '-':;.WhllfJ R,ver
"-
~
I
"
2
115 KV From ."-
Swan Lake .. ····· "
(Planned) --.......:
GRAVINA ISLAND
:.
ISLAND
ALASKA POWER ADMINISTRATION
;KETCHIKAN a METLAKATLA
EXISTING POWER
SYSTEMS
Scole
0,. ~ 2 :3 4 5 mi ---.... o 1 2 3 4 5 6 7 8 9 10km
APA -MAY 1979
PART IV. POWER REQUIREMENTS
ROUGH. DRAFT
Revised 12/15/82
Ketchikan area power requirements were estimated through year 2000.
Thi s was primari ly an update of a sim"j 1 ar est"imate "j n SeptelTIber 1979 and
republished in February 1980. The previolJs studies also included
estimates of power needs for Metlakatla, which has since sought development
of the Chester Lake project to meet its own needs. This present analysis
omits Metlakatla because electric interconnection with Ketchikan is not
expected within the time frame of Mahoney Lake development and buildup
to full utilization.
Power requirement estimates were based on examination of historic power
use plus present ~nd projected economic conditions and power generation
sources expected to affect the power market.
Historic Power Use
Ketchikan electric power use demonstrated overall steady growth with
generally consistent patterns during the 1970's. R~pid increases
occurred in 1981 and the first.half of 1982. T.he increases are due
generally to a shift to electric heat due to price increases in fuel
oil; and are similar to trends in Juneau. and Sitka which also have a
hydro power generation base as will Ketchikan on completion of the Swan
Lake project.
G-10
Power use data are summarized in Table 3 and Table 4.
Residential use peaked in 1973, dipped, stabilized in 1978-79, increased
in 1980, and dramatically increased in 1981 and (not shown) in early
1982. This sector is significant in projecting future power needs. The
rapid increase is due to a very high percentage of new construction
utiliz.ing electric heat because of low initial cost, recent fuel oil
price increase, and projected competitive cost power as Swan Lake comes
online. Similar trends were seen in Juneau for the same reasons, plus
1980-1981 heating requirements being at or above long-term average
following several mild winters. Ketchikan heating requirements were not
as dramatically different as Juneau, contributing less to the reasons.
for energy increase. Ketchikan 1979-1982 (estimated) per capita residentia1-
energy increases were about one-third Juneau increase rates (2.7 percent
1979-80,7.2 ~ercent 1980-81, and estimated 9.4 percent 1981-1982).
Factors Affecting Power Use
Economic, social, and institutional factors which are expected to affect
future power demands are:
o Housing construction was growing strongly in 1981 and 1982, and is
expected to continue at a moderate rate. ~1ost structures are more
thermally efficien.t than existing buildings.
o Construction of the Borax mine would cause some increase in electric
demand duringconstructton and significant increase after mine
operation begins.
G-ll
TABLE 3. KETCHIKAN ELECTRIC POWER USE SU~1MARY
Net Energy ]j Peak Load Energy
Year GWH Load Factor Growth
MW % %
1965 47.9 10.1 54.1
6.9
1966 51.2 10.5 55.7
-0.2
1967 51.1 10.3 56.7
5.5
1968 53.9 11.1 55.4
2.8
1969 55.4 10.7 59.1
10.3
1970 61.1 11.8 . 59.1
3.6.
1971 63.3 12.4 58.2
6.2
1972 67.2 12.5 61.4
7.1
1973 72.0 . 14.1 58.3
0.7
1974 72.5 13.4 61.8
5.0
1975 76.1 13.7 63.4
4.2
1976 79.3 14.0 64.7
1.5
1977 80.5 16.3 56.4
5.2
1978 84.7 15.1 64.3
0.5
1979 85.1 16.1 60.3
5.9
1980 90.1 17.7 58.0
3.8
1981 93.5 16.9 63.2
14.0
1982 2/ 106.6 19.1 . 61.8
Average 1965-1981 59.4 4.3
1970-1981 60.8 3.9.
1975-1981 61.5 3.5
1/ Includes LPK interchange.
2/ Projected based on Jan-June data.
APA-Revised 12/15/82
G-12
_ ... _--'----",------------~----------~------------_._-_._ .. _----
TABLE 4. KETCHIKAN ELECTRIC POWER USE
..l2.Z.Q... 1971 1972 1973 1974 .llli.... 1976 1977 1978 1979 1980 ~ 1982
Jan-Jun
Energl Sales {MWHl
Residential 27,128 29,246 30,797 30,958 31,128 32,838 35,059 35,082 36,754 37,462 39,135 42,834
Commercial 16,024 16,604 17,680 19,979 20,313 25,077 25,786 25,236 27,682 28,698 29,371 31,055
Industrial 9,357 9,463 9,295 9,271 7,147 4,770 4,868, 5,265 5,554 5,004 3,914 5,708
Other 1;384 1,521 1,572 1,549 1,385 1,431 1,259 1,109 1,136 1,050 1,328 1,866
iotal 53,893 56,835 59,344 61,757 59,973 64,116 66,972 66,692 71,126 72,214 73,748 81,464 52,645
Energl Sold Growth Rate Percentage {from ~revious lear}
Resid.ential 7.8 5.3 .5 .5 5.5 6.8 6.6 4.8 1.9 4.5 9.5
Corr.'11ercial· 3.6 6.5 13.0 1.7 23.5 2.8 -2.1 9.7 3.7 2.3 5.7
Industrial 1.1 -1.8 -.3 -22.9 -33.3 2.1 8.2 5.5 -10.0 -21.8 4.6
Other 9.9 3.4 -1. 5 -10.6 3.3 12.0 -11. 9 2.4 -7.6 -26.3 40.5
Total T.5' 4:4 4":T :--z:g ~ 4.5' ~ """b.b l:""5"" ---z:r ro:-5"" I2.9
Percent of Total Energl Sold
Resi denti a 1 50.3 51. 5 51. 9 50.1 51. 9 51.2 52.3 52.6 51. 7 51. 9 53.1 52.6
Commercial 29.7 29.2 29.8 32.4 33.9 39.1 38.5 . 37.8 38.9 39.7 39.8 38.1
Industrial 17.4 16.6 15.7 15.0 11. 9 7.4 7.3 7.9 7.8 6.9 5.3 7.0 ;;.., Other 2.6 2.7 2.6 2.5 2.3 2.2 1.9 1.7 1.6 1.5 1.8 2.3 I
W Number of Retail Customers
Residential 3,067 3,193 3,281 3,569 3,754 3,837 4,019 4,173 4,312 4,393 4,469 4,561 4,639
Commercial 563 586 580 616 661 641 644 662 653 631 668 744 769
Industrial 24 21 57 21 10 10 10 10 10 10 6 6 6
Other 355 381 383 411 405 408 398 421 419 411 404 405 404
Total 4,009 4,18f 4,3Of 4,6iI 4,830 "4,89'6 '5,071 P66 ~ ~ '5";"54T m6 5,808
Percent of Retail Customers
Residential 76.5 76.4 76.3 77.3 77.7 78.4 79.3 79.2 79.9 80.7 80.6 79.8 79.8
Comme rc·i a 1 14.0 14.0 13.5 13.3 13.7 13.1 12.7 12.6 12.1 11. 6 12.0 13.0 13.2
. Industrial .6 .5 1.3 .5 .2 .2 .2 .2 .2 .2 .1 .1 .1
Other 8.9 9.1 8.9 8.9 8.4 8.3 7.9 8.0 7.8 7.5 7.3 7.1 6.9
Energl Use ~er Retail Customer -KHH Eer Year
Resid(!ntial 8,845 9,159 9,386 8,674 8,292 8,558 8,723 . 8,407 8,524 8,528 8,757 9,391
Commercial 28,462 28,334 30,483 32,433 30,731 39,122 40,040 38,121 42,392 45,480 43,969 41,741
Industrial 389,875 450,619 163,070 441,476 714,700 477,000 486,800 526,500 555!400 500,400 652,333 953,000
Total 13,443 13,594 13,798 13,376 12,417 13,096 13,207 12,665 13,186 -rr;262" 13,295 14,253 --g,orr
APA -12/82
o Electric space heat was installed in most new homes during 1981.
o Resistance heat was planned for a large grou~ of condominiums and a
hotel scheduled for construction in 1982 and 1983.
o KPU has proposed thermal performance standards for electrically
heated buildings.
o KPU is encouraging use of high-efficiency heating systems such as
heat pumps, and instituted a verification program in an effort to
reduce the energy use for space heating.
Future Power Regui rements .
i
Estimates were made for three loads or "cases" of power requirements for
Ketchikan--low, medium or "basel!, and high. These. cases are premised
on:
low -
base -
high -
continued no.rmal power use. growth without electric heat
continued normal power use growth plus electric heat
base plus Borax construction and operation employees residing
in Ketchikan (including electric heat)
G-14
Method
Power needs were estimated by calculating residential use in detail and
prorating commercial, i.ndustrial and other power use on a historic
basis. Electric heat was added with a set of assumptions on when electric
heating would start, how fast it would grow and the percent of homes
that would use it. Borax employees, as residents, were added to the
number of customers along with an estimated number of support and service
people.
Assumptions
Low Case (Table 6)
o Economic:conditions will continue increasing at a slow rate with a
cyclical but stable timber industry. The salmon and halibut fishery
will remain stable with a sniall bottom fishery addition. Some
increase in Native corporation actlvity is expected.
o Population will increase at the long-term average of 2 percent
annua lly.
a People per residential customer will be constant at 2.5.
a Energy use ~illbe 10,280 kWh/customer for residential customers
after 1982 and decrease following full utilization of Swan Lake.
G-15
o The relative distribution by sector will remain stable at the
following historic percentages:
Residential
Commercial
Industrial
Other
52%
39%
2%
2%
o The heavy industrial uses, such as the pulp mill, will supply their
own needs. Minor exchanges will continue.
o System transmission and distribution losses will continue at 15
percent through 1985 then decrease to 12 percent through year 2000.
o System capacity factor will remain near the historic average of
60 percent.
Base (Medium) Case (Table 7)
o Non-heat power requirements will be the same as for the low case.
o About 35 percent of existing (pre-1980) residences will convert to
electric heat by year 2000. (1981 and 1982 conversions are included
in historic data).
(;-16
o New residences will increase from 70 percent electric heat in 1983
to 90 percent 1985 then remain constant (1981 and 1982 experience
is between 70 and 90 percent). (New 1981 and 1982 electric heat
customers are included in historic data).
o Electric heat residential customers will use 22,880 kWh/yr total
(10,280 kWh non-heat and 12,600 kWh heat).
o Electric heat commercial will total 15 percent of total residential
heat.
o Electric heat demand will have 30 percent plant factor.
High Case (Table 8)
o Base case plus addition of Borax employees and support services.
These include:
one-fifth (200) of 1,000 construction employees from 1984
through 1986, plus 200 support cormnunity service ·employees
(municipal, food and retail, education, medical, transportation,
etc.) .
860 permanent operating employees would reside in Ketchikan,
plus an equal number of community support service people
(1,720 total). One-third of these people (440) would be added
in each 1987, 1988, and 1989.
G-l7
The 10ng-term energy growth rate prior to 1981 was 4.3 percent annually.
Discreet annual rates since 1965 range from -0.2 percent to 10.3 percent,
reflecting specific economic and weather conditions. Long-term average
system load factor has increased slight1y, being highest in the mid-
1970's and averaging just over 60 percent. These data ar~ from a period
of time when generating capacity was about 60 percent diesel and 40
percent hydro.
Particular components of power use are presented in Table 4.
The rapid increase in energy sales in 1981 and the first 6 months of
1982 is shown--l0.5 percent and 12.9 percent respectively-~compared with
a 1971-1980 average of· 3.2 percent. Total salesals~ indicate about 15
percent losses and util ity use from total net generation. Sector energy
sales fractio.ns were fairly consistent at ·52 percent residential. 39
percent commercial •. 7 percent industrial and 2 percent other. Retail
residential customers :increased about 2 percent annually from 1978
through June 1982, and sect6r portions of total number of customers w~s
steady at about 80 percent residential, 13 percent corrunercial, 0.1
percent industrial, and 7 percent other. Per capita energy use varied
slightly between 1970 and 1980 from a high of 13,798 in 197~ to a low of
12,417 in 1974. The industrial sector per capita use varied widely
depending on economic conditions (fish processing).
G-1S
Estimates
the percentage and per capita electric heat use would be the
same as for the base case, with a~ other factors also being
constant.
Future power requirement estimates are summarized in Table 5 and presented
in Tabl~s 6, 7, and 8.
In summary, the low case energy estimate increases at an annual rate of
2.4 percent from 1982 to 2000, and the base and high estimates increase
4.2 percent and 5.6 percent respectively. Peak demand increases correspondingly
by 3.7 percent, 6.4 percent, and 7.9 percent annually.
Comparison With Pr~vious Estimates
Several estimates of power needs for Ketchikan have been made during the
past two decades. The estimated growth has varied through a rather
narrow margin of only 4 to 7 percent annually. The 1968 Alaska Power
Administration Feasibility requirements would increase at the rate of
7 percent. In 1974 Advisory Committee Report for the Federal Power
Commission, Alaska Power Survey used an estimate of 5 percent "in projecting
Ketchikan loads to 1990. The February 1979 application for the Swan
Lake Project FERC license, prepared by R.W. Beck and Associates for the
city of Ketch"ikan, assumed 5 percent annual energy increase for
G-19
Table 5. KETCHIKAN AREA ELECTRIC LOAD ESTIMATE
SUMMARY OF CASES
LOl·J BASE HIG·H
---------------------------------------------------
\\let P'2a k ~·Jet PI? c". f·: Net P·~ak
G<? 1"I<?1-' a t i <)n D~2man d G<? nlO.';-· a t i<)n D<?mand 13'2 nel-' at ion D:?'Tland
'-('-201.1-' GWH Ml.-J GWH 1'1W GWH i'1W
_1 '3·3_t I=J:~:. 5 .iE;. '3 9~~: • <:: 1';:;. "::' 9:;:.5 .16. '3 .J
1::'.92 105. ~ 24 • .1 .105.7 24 • .1 105.7 24.1 (
1'3,<.33 107. ..." Z4.6 1.12.3 2E:. :~: 1.12. :;: 2E;"~: I
1 ''=, ,?A 109.,'=!. 25 •. 1 117.0 '-;"7 0 ':"'1 • I_I L::O.4 ~:.1. 6
.1';;,'=!,5 Lt.1. '=' 25.5 122.1 2'3.4 134.9 ==~::::. 0
1'38.6 .114 • .1 2E;.O 126.9 30.9 140.0 34.6
19e.7 .1.16.2 26.5 .1:3.1 • .'3 ::::2.5 .16.1.0 4C.,s
1'38,'3 .11,~,. 4 '?7 .0 _t37.0 ::::4 .1 j)31.7 47.0 ~I
"
.19,'39 120.5 .-.. ",=" t::" 142.0 :;:5" 7 202.7 5:::.2 Li • '-1
1990 122.5 Z.g.o .14E:. '.:! '-I~ --:' 207.:3 54.7 .:.,{ • ,_I
19'35 1::::4.0 :30.E; .. t7~: .. 9 45. '.,.. 2::::4.0 8:::: • .1 (
2000 14·6.5 ~:3.4 202.5 54.,~· 262.7 72 . .1
AF'A -Rev i s,.?d
1.'-"'/1"'" /O~~ '6-.J, \...~
G-20
G")
I
N
->
TABLE 6.
(Ac t 'J a 1 )
Fis,:al Year' .1.91H l.'3,~,2 1'3133
===========:= ~===== :==::== ======
P<:'pu 1 at i<.n .11, ~:7:3 11.830 11, ,~,50
P~opl<? per Custo:·mer 2.4':; 2.5 2~5
Residential C,'J s t<.m(or· s 4,56l. 4. E:52 4.740
fo:WH/Cu s t.:·m'21' '3, :;:'31 10,280 10,280
Residential Sales (52~~ )
Million KWH 42.8 47 •. 9 48.7
/ ,
(52.6) [ lJ
C.,mmer cia 1 Sales ( 3'3;';~
Million K~JH 31.1 35,.'3 38.5
f:3,s.1 )
Ir,d'Jstrial (7:-; )
Milli<;>n ~a;JH 5.7 6.4 6.5
(7.0)
Other (2;,; )
Milli(·n fo:WH 1.9 1.8 1.9
(2.3)
T<:.t a 1 SalE-s, Millior, KWH ,~.1.5 91'.'3 93.6
Net Generatic)fI,
Million ~:WH [ 2J 93.5 105.7 107.7
Peak Demand. MW (:;: ] 16.9 24.1 24.8
(1] 1981 X o~ total sales.
[21 Includes distribution s7stem losses o~ 15%.
C31 Bas~d on 50% system load ~actor.
~:ETCHIf<AN
1'3,~.4
======
1" "-, 100
2.5
4,840
10,2.'30
49.8
37.1
8.7
1.9
95.5
109.8
25.1
AREA ELECTRIC LOAD ESTIMATE
LOW CASE
19,~,5 198,8 19!37 l'38e·
=::==== ====== ====== ===:===
12.350 12.600 12.S50 13.100
2.5 2.5 2.5 2.5
4,940 '5,040 5,140 5.240
10,280 10,2e,0 10,2.'30 10,280
50.8 51. .'3 52 •. 9 53.9
37.8 3e .• 5 39.2 3.'3.9
6.e: 8.9 7.0 7.2
1.9 2.0 2.0 2.0
97.3 99.2 101.0 103.0
111.9 114.1 118.2 118.4
25.5 28.0 26.5 27.0
1989 1990 .
======= ==:::===
13,375 13,825
2.5 2.5
'5,350 5,450
10,2E:O 10,2:::0
'54.9 55.S
40.5 41.2
7.3 7.4
2.1 .., ,..."
~ . ..:...
104.,~. 106.6
12tr~5 122.5
27.5 ze·.o
1'395 2000
=====::: ======
15,050 18,825
2.5 2.5
6,020 E:,650
10,1::::0 10.030
61.0 8E:.7
45.1 49.3
8.1 e .. 9
2.3 2.5
118.5 127.4
134.0 146.5
30.E: 3:3.4
APA -RE-vised
12/15/.S2
============
Pc'pulati(.n
P~ople pe~ Customer
Residential Custome~s
KWH/C'J s tomer
======
11.373
2.49
'4.581
'9. :::91
TABLE 7.
1'382
======
11.830
2.50
4.852
10.2.C!.0
1983
======
11,850
2.50
4,740
10.2.'30
Residential Sales (52%)
Mi 11 ion ~:WH 42.8 47.8 4,g.7
(52.8) [1]
Commerci~l Sal~s (39%)
Mi l1.i on ~:WH
Ind'Js t~i. a 1 (7%)
Million KWH
Othel~ (2%)
Million KWH
Total Sales, Hi 11 ion KWH
N.?t Genel~at{on,
Millic.r, KWH [2]
Pea~ Demand. MW [3]
Electr'ic Heat
Customers
Net Gener'ati<:>n.
Mi 11 ion I':WH
Peal< Demand
31.1
(:;:8.1 )
5.7
(7.0)
1.9
(2.3)
81.5
93.5
16.9
[41
Total Normal Use a Elect~ic Heat
Net Gene~ation. Million KWH
Pea~ Demand. MW.
[1] 1981 % of total sales.
:;:.5.9 38.5
8.4 6.5
1.8 1.9
91.9 93.6
105.7107.7
24.1 24.6
[41
277
4.6
1..g
112.3
28~:;:
[2] Includes distribution system losses of 15%.
13J Based on 50% load factor.,
KETCHIKAN AREA ELECTRIC LOAD ESTIMATE
BASE CASE: LOL-J CASE PLUS ELECTRIC HEAT
=======
12,100
2.S0
4, .'340
10.2.C!.a
49.8
37.1
6.7
1.9
95.5
109.8
25.1
714
7.2
2.7
::=====
12.350
2.50
4.940
10.2.';.0
50.e.
37.8
6.e.
1.9
~7.3
111.9
25.5
891
10.2
3.9
117.0' 122.1
27.'e. 29.4
====:::=
12.600
2.50
5.040
10.2.C!.0
51.8
3oS.5
6.9
2.0
99.2
114.1
28.0
1,088
12.8
4.9
126.9
30.9
1'387
======
12,."!.50
2.50
5.140
10. ze.o
52.8
39.2
7.0
2.0
101.0
116.2
26.5
1.640
15.6
5.9
131.8
=======
13,100
2,.50
5,240
10.2·'30
53.9
7.2
2.0
103.0
11."!..4
27·.0
2,213
18.6
7.1
137.0
34.1
[4] 1981 a 1982 existing customers included above.
198'3
13, :375
2.S0
5,350
10,260
54.9
40.5
7.3
2.1
104.8
120.5
27.5
2,795
21.5
8.2
142.0
:::5.7
1990
13.625
2:50
5.450
10.230.
55.e.
41.2
7.4
2.2
106.6
122.5
2,972
24.4
9.3
146. 9
1995
======:
15.0S0
2.50
6.020
10,1::::0
45.1
."!·.1
2.3
llE:.5
134.0
:;:0.6
3,'320
:39.,S
15.1
173 .. &·
45.7
2000
18. E:;:5
2.S0
6. t:50
10,0::0
66.7
49.3
8.9
2.5
127.4
146.5
33-.4
4.921
56.0
21.3
202.5
54 .. C!.
APA -Revised
12/15/.'!.2
~
I
1",;)
w
TABLE ~'. KETCHn;AN AREA ELECTRIC LOAD ESTIMATE
HIGH CASE -INCLUDES B.ORAX EI'1PLOYEES LIVING IN KETCHn;AN
Fis':al Y~~r 1·:'·~·1 1·,j·~.2 1'38:;:
=====:===:.=::=-=~ ------====== ======
p('F' III i\ t i (,r. 11, -3?:;: 11, ';:;:30 11, 850
F'e(·p Ie F' <?l' CllS t.:,m>?l' 2.4'3 2 .. 50 2.50
F:<-=id<?nti.i\l Cllst(,m,.:r·s 4, '561 4, 652 4,740
~:\'JH/CIl s t.:,m· .. r· '3,391 10. 2·~,0 10, 2130
Resid<?r.tial Sal<?s ( 52~':)
Milli<:.rl ~a·JH 42.8 47.8 4,3.7
(52.6) [1]
C.:,mm<?I··': i a 1 Sales (3'3;·; )
I'1i 11 iNI f':WH 31.1 35.'3 3E:.5
(3,~ .• 1)
Indllstl··ial .( 7~';)
Million ~;WH 5.7 6.4 8.5
(7.0)
Oth<?r' (2;·;)
I'1illiN' ~:WH 1.9 1..9 1.9
(Z.3)
T<:.t al Sa les, Milli<:,n ~:WH ·91.5 '31. 9 '33.8
N<?t G(-rrter'atii,n ,
Milli<:,n ~:WH [2] -='3.5 105.7 107.7
P'?a k Demi'.nd. M~J [:;:] H:.'3 24.1 24.6
El",o:tric Heat
Clls·t<,mE'r·s 277
N<?t Genel··ati<:.n.
Milli<:.n K~JH [4] [4] 4.6
. PI!:' a k Dl!:'mand 1..8
Total N<:,r'mal Use .!-: Electric HE'at
,Net GE'rreration, Million ~;WH 1.12.3
Peak [lema ro d, MW 26.~
[1] 1981 % o~ total sales.
[2] Includes distributi6n system los5e5 of 15%.
[3] Based <'n 50;~ l<:>ad .fact<:,r·.
[4] 1981 & 1.982 existing customers i~o:luded above.
19!?-4 1'385 19,% 1·3·~.7 19.~.8
====== ====== ======= ====== ======
13, .100 13, :350 1·'" "-'J 800 14, '350 16,:300
2.50 2.50· 2.50 2.50 2.50
5, 240 5, 340 5.440 5, '380 8, 520
10, 2,~,0 10. 2.?0 10. ze.o 10, 2.'30 1.0. 2·~,0
5::::.9 54.9 55.'3 61.5 67.0
39.9 40.5 41.2 44.9 4.~,.5
7.2 7.3 7.4 ,~,.1 .9.7
2.0 2.1 2.1 2.3 2.5
10:;:.0 104.8 108.6 11E:.,9 lZ6.7
1.HI.4 120.5 i22.E; 134.3 145.7
27.0 27.5 28.0 :30.7 33.;;:"
714 891. 1. 068 1, 640 .., .... 21?"'
12.0 1.·l.4 1.7.4 2E:.7 36.0
4.6 ?5 E:.€: 10.2 1:;:.7
1.::::0.4 134.9 .1.40.0 161..0 1,91.7
31.6 33.0 34.6 40.8 47.0
8, ELECTRIC HEAT
19.~,·3
======
17. E:·SO
2.50
7,. 0""-' ( "-
10. ZE:O
72.6
52.1
9.4
2.7
136.8
1.57.3
35.'3
2. 7'35
45.4
17.:;:
202.7
5::::.2
1990 1'39'5 2000
======= ====== ==-====
17, 'no
2.50
fl, 168
10, 230
73.3
52.eo
9.5
2.7
138.:3
1.59.1.
36.3
-., "-. G"'-' -( "-
48.2
1,':?.3
207.3
54.7
1'3,350 20, '320
2.50 Z.50
7 . 740 ,g, :36,'=,
10, 130 10, 030
78.4 ·g3.'3
56.7 81.0
10.2 10.'3
2.9 3.1
148.2 lS,'?. '3
170.4 1·92.,~,
~~'~'. '3 41.7
3. '320 4. 921
E:3.6 79.9
24.2 ::;0.4
2:34.0 2E:2.7
63.1 72.1
APA -Revised
1.21 15 1,~,2
the foreseeable future, based on a long-term trend since 1935. The Beck
estimate of peak demand is slightly less than the base case, while the
energy estimate matches the base casein 1987 and approaches the high
case in 2000 due to compounding.
G-24
APPENDIX H
PUBLIC VIEWS AND RESPONSES
APPENDIX H
PUBLIC VIEWS AND RESPONSES
This appendix will contain the public comments on this draft document.
ARLIS
Alaska Resources
Library & Information Services
AnchoraRe .. ~aska
APPENDIX I
STATEMENT RECIPIENTS
FEDERAL
APPENDIX I
STATEMENT RECIPIENTS
Board of Engineers for Rivers and Harbors
U.S. Department of Energy, Alaska Power Administration
Heritage Conservation and Recreation Service
Advisory Council on Historic Preservation
U.S. Geological Survey, Water Resources Division
Area Director, Bureau of Indian Affairs
State Oirector, Bureau of Land Management
Director, Office of Environmental Project Review, U.S. Department of
Interior
National Oceanographic Data Center, National Oceanic and Atmospheric
Administration
Regional Director, National Marine Fisheries Service
Regional Forestor, U.S. Forest Service
Director, Alaska Operations Office, Environmental Protection Agency
Field Supervisor, Southeast Alaska Ecological Services, U.S. Fish and
Wildlife Service
Regional Director, U.S. Fish and Wildlife Service
Special Assistant to the Secretary, U.S. Department of Interior
Commander, 17th Coast Guard District
Division Engineer, North Pacific Division
U.S. Department of Housing and Urban Development
U.S. Department of Commerce, Economic Development Administration, Anchorage
U.S. Department of Commerce, Economic Development Administration, Seattle
Regional Director, Federal Aviation Administration, Department of
Transportation, Alaska Region
Honorable Ted Stevens, U.S. Senate
Honorable Frank Murkowski, U.S. Senate
Honorable Don Young, U.S. House of Representatives
Area Director, Heritage Conservation and Recreation Service
Director, Bureau of Mines, U.S. Department of Interior
Alaska Field Operations Center, Bureau of Mines
Manager, Alaska Outer Continental Shelf Office, Bureau of Land Management
National Park Service, Juneau
National Park Service, Anchorage
Environmental Protection Agency, Region X
Environmental Protection Agency, Washington, D.C.
Office of the Secretary, U.S. Department of Agriculture
DAEN-CWP-E Department of the Army, Civil Works Project, East
DAEN-CWP-W Department of the Army, Civil Works Project, West
DAEN-CWP-C Department of the Army, Civil Works Project, Central
American Institute of Merchant Shipping
Evaluation Branch, Coastal Engineering Research, Corps of Engineers
Commander/Director, U.S. Army Cold Regions Research Lab
Director, Environmental Impact Division, Office of Environmental Programs,
Federal Energy Administration
Director, Alaska Region, National Weather Service
Deputy Assistant Secretary for Environment, U.S. Department of Commerce
District Director, Small Business Administration
Director, Office of Environmental Review (A-104), Environmental Protection
Agency
STATE
Office of the Govenor, Juneau
Alaska Department of Transportation and Public Facilities, Southeast Region
Division of Policy Development and Planning, Alaska Coastal Management Plan
Alaska Department of Natural Resources, Division of Parks
Alaska Department of Commerce and Economic Development·
Alaska Department of Environmental Conservation, Juneau
Alaska Department of Environmental Conservation, Anchorage
Alaska Department of Environmental Conservation, Southeast Regional.Office,
Juneau
Alaska Department of Revenue
State Federal Coordi~ator, A-95 Clearinghouse, Division of
Planning
Director, Division of Harbor Design and Construction
Division of Policy Development and Planning, Alaska Coastal Management
Program .
Department of Transportation and Public Facilities,
Southeast Region
Alaska Department of Fish and Game
Commissioner, Department of COl1ll1unity and Regional Affairs
Director, Division of Land and Water Management
Alaska Department of Natural Resources, Southeast District
Commissioner, Department of Natural Resources
Director, Division of Land and Water Management
Department of Community and Regional Affairs, Local Government Assistant
Division
Southeast Alaska Conservation Council
State of Alaska Water Resources Board
ORGANIZATIONS
Alaska Native Brotherhood
Trustees for Alaska
American Institute of Architects
American Society of Civil Engineers
Leader, Cooperative Wildlife Research, University of Alaska
Director, Institute of Marine Sciences, University of Alaska
Library, University of Alaska, College .
Library, University of Alaska, Anchorage
Z.J. Loussac Library
President, Alaska State Chamber of Commerce
American Institute of Merchant Shipping
Director, Institute of Water Resources, University of Alaska
Arctic Information and Data Center
President, Anchorage Chapter, Izaak Walton League of America
State Representative, Friends of the Earth
Executive Director, Alaska Wildlife Federation and Sportsmen Council
Sierra Club, ReC
Juneau Group/Sierra Club
Southeast Alaska Conservation Council
Cape Fox Corporation
1-2
LOCAL
Mayor of Ketchikan
United Fishermen of Alaska
KetchiKan City Manager
Chamber of Commerce, Ketchikan
Postmaster, Ketchikan
SealasKa Corporation
KetchiKan Library
City of Saxman
Gateway Borough
ARLIS
Alaska R
L 'b eSOurces 1 rary & I f" nlormation Ser' .
AnchofCtQ"f.. /\lRSka VIces
1-3