HomeMy WebLinkAboutAPA533ALASKA POWER AUTHORITV
ANCHORAGE, ALASKA
CHAKACHAMNA HVDROELECTRIC PROJECT
INTERIM REPORT
NOVEMBER 30, 1981
Bechtel Civil & Minerais, lnc.-San Francisco Job 14879
ALASKA POWER AUT'HORITY
ANCHORAGE, ALASKA
CHAKACHAMNA HVDROELEC:TRIC PROJECT
INTERIM REP 10RT'
NOVEMBER 30, 11981
Bechtel Civil & Minerals, Inc.-San Francisco ·Job 14879
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ALASKA POWER AUTHORITY
ANCHORAGE ALASKA
CHAKACHAMNA HYDROELECTRIC PROJECT
INTERIM REPORT NOVEMBER 30, 1981
TABLE OF CONTENTS
INTRODUCTION
SUMMARY
2.1
2.2
2.3
2.4
2.5
Project Layout Studies
Geological Studies
Environmental Studies
Economie Evaluation
Technical Evaluation and Discussion
PROJECT DEVELOPMENT STUDIES
3.1
3.2
3.3
3.4
3.5
3.6
Regulatory Storage
Chakachatna Dam
McArthur Tunnel Development
3.3.1
3.3.2
Alternative A
Alternative B
Chakachatna Tunnel Development
3.4.1
3.4.2
Alternative c
Alternative D
Transmission Line and Submarine Cable
References
HYDROLOGICAL AND POWER STUDIES
4.1
4.2
4.3
4.4
4.5
4.6
Introduction
Historical Data
Derived Lake Inflows
Power Studies
Results
Variations in Lake Water Level
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Page
1-1
2-1
2-1
2-3
2-4
2-9
2-9
3-1
3-1
3-2
3-5
3-5
3-8
3-9
3-9
3-11
3-12
3-13
4-1
4-1
4-2
4-3
4-4
4-10
4-11
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6.6
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Human Resources
6.5.1
6.5.2
6.5.3
6.5.4
6.5.5
6.5.6
6.5.7
6.5.8
Background
Archaeological and Historie
Re sources
Land OWnership and Use
Recreation
Socioeconomics
Community Infrastructure
Transportation
Visual Resources
References
EVALUATION OF ALTERNATIVES
7.1
7.2
7.3
Engineering Evaluation
7.1.1
7.1.2
7.1.3
7.1.4
7.1.5
General
Chakachatna Dam
Alternative A
Alternative B
Alternatives C and D
Geological Evaluation
7.2.1
7.2.2
7.2.3
7.2.4
Chakachatna Dam
Alternative A
Alternative B
Alternatives C and D
Environmental Evaluation
7.3.1
7.3.2
7.3.3
Chakachatna Dam
McArthur Tunnel Alternatives A
and B
Chakachatna Tunnel Alternatives
C and D
CONSTRUCTION COSTS AND SCHEDULES
8.1 Estimates of Cost
8.1.1
8.1.2
8.1.3
8.1.4
Power Tunnel
Underground Powerhouse and
Associated Structures
Tailrace Channel
Switchyard
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Page
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6-85
6-87
6-95
6-122
6-125
6-137
6-141
6-147
6-150
7-1
7-1
7-1
7-2
7-2
7-3
7-4
7-7
7-7
7-8
7-9
7-10
7-11
7-11
7-12
7-16
8-1
8-1
8-3
8-5
8-6
8-7
8.0 CONSTRUCTION COSTS AND SCHEDULES (Cont'd.)
9.0
10.0
8.2
8.3
8.1.5
8.1.6
Transmission Line and Cable
Crossing
Site Access and Development
Exclusions from Estimates
Construction Schedules
ECONOMIC EVALUATION
9.1
9.2
9.3
9.4
9.5
9.6
General
Parameters for Economie Evaluation
Cost of Power from Alternative Sources
9.3.1
9.3.2
9.3.3
9.3.4
General
'Construction Cost
Operation and Maintenance Cost
Fuel Cost
Value of Hydro Generation
Economie Tunnel Sizing
Economie Tunnel Length
1982 STUDY PROGRAM
10.1 Engineering Studies
10.1.1
10.1.2
10.1.3
10.1.4
10.1.5
10.1.6
10.1.7
10.1.8
10.1.9
Hydro1ogical Studies
Chakachatna Dam
Reservoir and Fish Passage
Faci1ities
Power Intake and Tunnel
Underground Powerhouse Comp1ex
Transmission Line and Submarine
Cable Crossing
Access Roads and Construction
Facilities
Cost Estimate and Construction
Schedule
Feasibility Report and License
Application
10.2 Geologie Studies
10.3 Environmenta1 Studies
10.3.1
10.3.2
10.3.3
10.3.4
Environmental Hydrology
Aquatic Bio1ogy
Wild1ife Biology
Human Resources
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9-1
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9-3
9-4
9-4
9-6
9-11
9-13
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10-1
10-2
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10-3
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10-4
10-4
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ALASKA POWER AUTHORITY
ANCHORAGE ALASKA
CHAKACHAMNA HYDROELECTRIC PROJECT
INTERIM REPORT NOVEMBER 30, 1981
INTRODUCTION
This report has been prepared in accordance with the
terms of the August 1981 contract between Alaska Power
Authority and Bechtel Civil & Minerals, Inc. in
connection with services for performing a feasibility
study and for preparing an application for an FERC
license to construct the Chakachamna Hydroelectric
Project. As its title indicates, the report is of an
interim nature. It is based upon previously published
information regarding the project, and on data acquired
and derived during a brief study period in the fall of
1981. Its objectives are to summarize the information
derived from the studies, to provide a preliminary
evaluation of alternative ways of developing the power
potential of the project, to define that power potential
and to report on the estimated cost of construction.
Although the data collected and study period are limited
by the short time base, sorne rather clear indications
have emerged as to the manner in which it is considered
that development of the project should proceed. Even
though sorne of the present data may be subject to
modification as the data base and depth of study are
expanded next year, the data presented in this report are
considered adequate to give realistic evaluations of the
power potential of the project and its cost of
construction.
1-1
~
For the assessment of
geological conditions in ~ project are
retained the services offwoodward-Clyde
As may be seen by reference to Figure 1-1, Chakachamna
Lake lies in the southern part of the Alaska Range of
mountains about 85 miles due west of Anchorage. Its
water surface lies at about elevation 1140 feet above
~
mean sea level.
The project has been studied and reported upon several
~t. The power potential had been
estimated variously from about 100,000 kw to 200,000 kw
firm capacity, depending on the degree of regulation of
the outflow from Chakachamna Lake and the hydraulic head
that could be developed.
Two basic alternatives can be readily identified to
harness the hydraulic head for the generation of
electrical energy. One is via the valley of the
Chakachatna River. This river runs out of the easterly
end of the lake and descends to about elevation 400 feet
above sea level where the river leaves the confines of
the valley and spills out onto a bread alluvial flood
plain. A maximum hydrostatic head of about 740 feet
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could be developed via this alternative. -
The ether alternative is for development by diversion of ~
the lake outflow to the valley of the McArthur River
which lies to the southeast of the lake outlet. A
maximum hydrostatic head of about 960 feet could be
harnessed by this diversion. Various means of
development by these two basic alternatives are discussed
in the report on the basis of the present knowledge of
the site conditions.
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2.0
2.1
SUNMARY
Project Layout Studies
The studies evaluated the merits of developing the
power potential of the project by diversion of water
southeasterly to the McArthur River via a tunnel
about lü-miles long, or easterly down the Chakachatna
valley either by a tunnel about 12-miles long or by a
dam and tunnel development. In the Chakachatna val-
ley, few sites, adverse foundation conditions, the
need for a large capacity spillway and the nearby pre-
sence of an active volcano made it rapidly evident
that the feasibility of constructing a dam there would
be questionable. The main thrust of the initial stu-
dies was therefore directed toward the tunnel alterna-
tives, with possibilities for a dam set aside until
1982 .
Two alignments were studied for the McArthur tunnel.
The first considered the shortest distance that gave
no opportunity for an additional point of access dur-
ing construction via an intermediate adit. The second
alignment was about a mile longer, but gave an addi-
tional point of access, thus reducing the lengths of
headings and also the time required for construction
of the tunnel. Cost comparisons and economie evalua-
tion nevertheless favored the shorter 10-mile 25-foot
diameter tunnel .
The second alignment running more or less parallel to
the Chakachatna River in the right (southerly) wall of
the valley afforded two opportunities for intermediate
2-1
access adits. These, plus the upstream and downstream
portals would allow construction to proceed simulta-
neously in 6 headings and reduce the construction time
by 18 months less than that required for the McArthur
tunnel. Economie evaluation again favored a 25-foot
diameter tunnel running all the way from the lake to
the downstream end of the Chakachatna Valley.
If all the controlled water were used for power genera-
tion, the-~u*---l2.9VI~hC:)U$e. could support 400 MW in-
stalled capacity, and produce average annual firm ener-
gy of 1753 GWh. The effects of making a provisional
reservation of approximately 19% of the average annual
inflow to the lake for instream flow requirements in
the Chakachatna River were found to ;cednce the economie
tunnel diameter to 23 feet. The installed capacity in
the powerhouse would then be_.reëluc~ to 330 MW and the
average annual firm energy to 1446 MW.
For the Chakachatna powerhouse, diversion of all the
controlled water for power generation would support an
installed capacity of 300 MW with an average annual
firm energy generation of 1314 GWh. Provisional reser-
vation of approximately 0.8% of the average Ênnual in~
flow to the lake for instream flow requirements in the
Chakachatna River was regarded as having negligible ef-
fect on the installed capacity and average annual firm
energy because that reduction is within the accuracy of
the present study.
The reasoning for the smaller instream flow releases
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~oReiàered in this alternative is discussed in Section
2.5
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Geological Studies
At the present level of study, the Quarternary Geology
in the Chakachatna and McArthur Valleys has been eva-·
luated and the seismic geology of the general area has
been examined though additional work remains to be
done next year. General observations as they may af-
fect the project are as follows:
The move of ice of the Barrier Glacier toward the ri-
ver may be gradually slowing. However, no material
éhange in the effect of the glacier on the control of
the Chakacharnna Lake outlet is anticipated.
The condition of the Blockade Glacier facing the mouth
of the McArthur Canyon also appears to be much the
same as reported in the previous USGS studies.
There does not appear to be any reason to expect a
dramatic change in the state of growth or recession of
either of the above two glaciers in the foreseeable
future.
Surface exposures on the left (northerly) side of the
Chakachatna Valley consist of a heterogeneous mix of
volcanic ejecta and glacial and fluvial sediments
which raise serious doubts as to the feasibility of
darnrning the Chakachatna River at this location.
The rock in the right wall of the Chakachatna Valley
is granitic, and surface exposures appear to indicate
that it would be suitable for tunnel construction if
2-3
2.3
2.3.1
that form of development of the project were found to
be desirable.
No rock conditions have yet been observed that would
appear to rule out the feasibility of constructing a
tunnel between the proposed locations of an intake
structure near the outlet of Chakachamna Lake and a
powerhouse site in the McArthur Valley. It must be
noted, however, that in the vicinity of the proposed
powerhouse location in the McArthur Canyon, the sur-
face exposures indicate that rock quality appears to
improve significantly with distance upstream from the
mouth of the canyon.
The Castle Mountain fault, which is a major fault
structure, falls just outside the mouth of the Mc-
Arthur Canyon and must be taken into account in the
seismic design criteria of any development of the pro-
ject whether it be via the McArthur or Chakachatna
Canyons. Other significant seismic sources are the
Megathrust section of the subduction zone and the
Benioff zone.
Environmental Studies
Hydrology
Field reconnaissances were conducted in Chakachamna
Lake, several of its tributary streams, the Chakachat-
na and Mc Arthur Rivers. Data collected and developed
are typical of glacial rivers with low flow in late
winter and large glacier melt flows in July and August.
2-4
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The water level in Chakachamna Lake when measured was
elevation 1142 and is typical of the September lake
stage records in the 12 years preceding the major flood
of August 1971. A lake bottom profile was surveyed on
the deltas at the mouth of the Chilligan River and -near
the Shamrock Glacier Rapids.
Reaches of the McArthur and Chakachatna Rivers vary
from mountainous through braided and meandering
streams. All except the most infrequent large floods
are mostly contained within the unvegetated flood
plain. Sedimentation characteristics appear to be
typically those of glacial systems with very fine sus-
pended sediments and substantial bed load transport.
Aquatic Biology
Field observations identified the following species in
the waters of the project area:
Resident: Rainbow trout
Lake trout
Dolly Varden
Round Whitefish
Pygmy Whitefish
Anadromous:Chinook salmon
Chum salmon
Coho salmon
Arctic grayling
Slimy sculpin
Ninespine stickleback
Threespine sticleback
Pink salmon
Sock~ye salmon
Dolly Varden
Sorne of the streams flowing into Chakachamna Lake con-
tain large areas used by spawning sockeye salmon and
2-5
2.3.3
substantual numbers of these fish were counted in the
Igitna and Chilligan Rivers. Evidence of potential
sockeye spawning was noted in Chakachamna Lake. Ju-
venile sockeye salmon use Chakachamna and Kenibuna
Lakes as nursery habitat. Lake trout, Dolly Varden,
round whitefish and slimy sculpin were also found in
these locations.
Side channels and tributaries of the Chakachatna and
McArthur Rivers contain salmonid spawning sites and
numerous fish were observed using them. These habi-
tats are also used as juvenile rearing areas. The
Noaukta Slough, a meandering reach of the Chakachatna
River is used extensively as a nursery area by juve-
nile fishes, particularly coho and sockeye salmon.
Juvenile pygmy whitefish and Dolly Varden are also
abundant in the slough. The intertidal ranges of both
river systems do not contain suitable habitat for
salmonid spawning or juvenile rearing.
Terrestrial Biology
On the basis of their structural and species composi-
tions, eight types of vegetation habitats were deli-
neated. These range from dense alder thickets in the
canyons to vast areas of coastal marsh. The riparian
communities are the most prevalent varying from rivers
with emergent vegetation to those with broad flood
plains scattered with lichen, willow and alder.
Evaluation of wildlife communities in the project area
identified seventeen species of mammals. Moose, coyote,
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grizzly bear and black bear ranges occur throughout the
area.
Birds also are abundant, fifty-six species having been
identified with the coastal marshes along Trading Bay
containing the largest diversity.
None of the species of plants, mammals and birds that
were found are listed as threatened or endangered al-
though in May 1981 it was proposed that the tule white-
fronted goose, which feeds and nests in the area, be
considered for threatened or endangered status.
Human Resources
These studies were organized into the following six
elements:
Archaeological and historical resources
Land ownership and use
Recreational resources
Socioeconomic characteristics
Transportation
Visual resources
Many contacts were made with both state and federal
agencies and Native organizations, as well as a limited
reconnaissance of the project area.
No known cultural sites have been identified and the
field reconnaissance indicates that the proposed sites
for the power intake and powerhouses have a low po-
2-7
tential for cultural sites.
Land owners in the area comprise federal, state, and
borough agencies, Native corporations and private par-
ties. Land use is related to resource extraction
(timber, oil and gas), subsistence and the rural resi-
dential Village of Tyonek.
Recreational activity takes place, but with the excep-
tion of Trading Bay State Game Refuge, little data is
available as to the extent or frequency with which the
area is used.
Regional data on population, employment and income
characteristics are relatively good. Employment level
and occupational skill data are limited and need to be
developed together with information on local employment
preferences.
Transportation facilities in the area are few and small
in size. There is an airstrip on the shoreline at
Trading Bay and a woodchip loading pier near Tyonek.
Several miles of logging roads exist between Tyonek and
the mouth of the Chakachatna Valley. The Chakachatna
River is bridged near its confluence with Straight Creek.
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here is no permanent road between the project area and •
any part of the Alaska road system.
The project area's scenic characteristics and proximity
with BLM lands, Lake Clark National Park and the Trad-
ing Bay State Game Refuge make visual resource manage-
ment a significant concern.
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Economie Evaluation
The studies demonstrate that the project offers an eco-
nomically viable source of energy in comparison with
the 55.6 mills/KWh which is the estimated cost of equi-
valent energy from a coal fired plant, apparently the
most competitive alternative source. Taking that figure
as the value of energy,the Chakachamna Hydroelectric
Project could begin producing 400 MW at 50% load factor
(1752 GWh) in 1990 at 37.5 mills/KWh if all stored
water is used for power generation. If approximately
19 percent of the water is reserved for instream flow
release to the Chakachatna River, the powerplant could
still produce 330 MW (1446 GWh} at 43.5 mills/KWh,
which is still significantly more economical than the
coal fired alternative. In both cases above, the power-
house would be located on the McArthur River. A power-
house on the Chakachatna River as described in the re-
port is barely competitive with the alternative coal
fired source of energy.
Technical Evaluation and Discussion
At this stage of the feasibility study several alterna-
tive methods of developing the project have been identi-
fied and reviewed. Based on the analyses performed, the
more viable alternatives have been identified for fur-
ther study in 1982.
Chakachatna Dam Alternative
The construction of a dam in the Chakachatna River ca-
nyon approximately 6 miles downstream from the lake out-
2-9
2.5.2
let, does not appear to be a reasonable alternative.
While the site is topographically suitable, the founda-
tion conditions in the river valley and left abutment
are poor as mentioned earlier in Section 2.2. Further-
more, its environmental impact specifically on the fi-
sheries resource will be significant although provision
of fish passage facilities could mitigate this impact
to a certain extent.
McArthur Tunnel Alternatives A and B
Diversion of flow from Chakachamna Lake to the McArthur
valley to develop a head of approximately 900 feet has
been identified as the most advantageous as far as
energy production at reasonable cost is concerned.
The geologie conditions for the various project facili-
ties including intake, power tunnel, and powerhouse ap-
pear to be favorable based on the limited 1981 field
reconnaissances. No insurmountable engineering prob-
lems appear to exist in development of the project.
Alternative A, in which essentially all stored water
would be diverted from Chakachamna Lake for power pro-
duction purposes could deliver 1664 GWh of firm energy
per year to Anchorage and provide 400 MW of peaking ca-
pacity. Cost of energy is estimated to be 37.5 mills
per kWh. However, since the flow of the Chakachatna
River below the lake outlet would be adversely affected,
the existing anadromous fishery resource which uses the
river to gain entry to the lake and its tributaries for
spawning, would be lost. In addition the fish which
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spawn in the lower Chakachatna River would also be im-
pacted due to the rouch reduced river flow. For this
reason Alternative B has been developed, with essen-
tially the sarne project arrangement except that appro-
xirnately 19 percent of the average annual flow into
Chakacharnna Lake would be released into the Chakachatna
River below the lake outlet to maintain the fishery re-
source. Because of the srnaller flow available for po-
wer production, the installed capacity of the project
would be reduced to 330 MW and the firrn energy deli-
vered to Anchorage would be 1374 GWh per year. The es-
tirnated cost of energy is 43.5 rnills per KWh. Obvious-
ly, the long term environmental impacts of the project
in this Alternative B are significantly reduced in corn-
parison to Alternative A, since the river flow is main-
tained, albeit at a reduced arnount.
Chakachatna Tunnel Alternatives C and D
An alternative to the developrnent of this hydroelectric
resource by diversion of flows from Chakacharnna Lake to
the McArthur River is by constructing a tunnel through
the right wall of the Chakachatna valley and locating
the powerhouse near the downstream end of the valley.
The general layout of the project would be sirnilar to
that of Alternatives A and B for a slightly longer po-
wer tunnel.
The geologie conditions for the various project fea-
tures including intake, power tunnel, and powerhouse ap-
pear to be favorable and very similar to those of Alter-
natives A and B. Similarly no insurrnountable engineer-
ing problems appear to exist in development of the pro-
ject
2-11
Alternative C, in which essentially all stored water
is diverted from Chakachamna Lake for power production,
could deliver 1248 GWh of firm energy per year to An-
chorage and provide 300 MW of peaking capability. Cost
of energy is estimated to be 52.5 mills per KWh. While
the riverflow in the Chakachatna River below the power-
house at the end of the canyon will not be substantial-
ly affected, the fact that no releases are provided in-
tc the river at the lake outlet will cause a substan-
tial impact on the anadromous fish which normally enter
the lake and pass through it to the upstream tributa-
ries. Alternative D was therefore proposed in which a
release of 30 cfs is maintained at the lake outlet to
facilitate fish passage through the canyon section into
the lake. In either of Alternatives C or D the environ-
mental impact would be limited to the Chakachatna River
as opposed to Alternatives A and B in which both the
Chakachatna and McArthur Rivers would be affected.
Since the instream flow release for Alternative D is
less than 1% of the total available flow, the power pro-
duction of Alternative D can be regarded as being the
same as those of Alternative C at this level of study
{300 MW peaking capability, 1248 GWh of firm energy de-
livered to Anchorage). Cost of power from Alternative D
is 54.5 mills per Kv7h.
The cost of energy from Alternative D is 25% greater
than that for Alternative B and is close to the cost of
alternative coal-fired resources. Therefore, it is
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planned that studies of the project to be performed in ~
1982 will concentrate on the McArthur River alternatives. -
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PROJECT
DEVELOPMENT
STUDIES
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3.1
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PROJECT DEVELOPMENT STUDIES
Regulatory Storage
The existing stream flow records show a wide seasonal
variation in discharge from Chakachamna Lake with 91
percent occurring from May 1 through October 31 and 9
percent from November 1 through April 30 when peak
electrical demands occur. The storage volume required to
regulate the flow has been reported to be in the order of
1.6 million acre-feet (USBR, 1962). The elevation of the
river bed at the lake outlet has been reported as
1127-1128 feet (Giles, 1967). This elevation is thought
to have varied according to the amounts and sizes of
solid materials deposited in the river bed each year by
the melting toe of the glacier, and the magnitude of the
annual peak outflow from the lake that is available to
erode the solid materials away and restore the river
channel.
The above-mentioned volume of regulatory storage can be
developed by drawing down the lake by 113 feet to
elevation 1014. It could also be obtained by raising the
lake 83 feet to a normal maximum operating water surface
of elevation 1210 and this would have the advantage of
increasing the hydraulic head available for development.
Previous studies of the project have discredited the
possibility of locating a control structure at the lake
outlet because its left abutment would have lain on the
toe of the Barrier Glacier. This is equally true today,
and it is concurred that there is no case for a control
structure at the lake outlet. According to USGS
measurements taken between 1961 and 1966, the glacier
advanced several feet per year at measuring stations
3-1
3.2
located about 100-150 feet from the river bank near the
lake outlet. Although no new measurements have been
taken in the present studies, the ice obviously undergoes ~
considerable movement as further discussed in Section 5.2
of this report.
Furthermore, the Barrier Glacier ice thickness was
measured in 1981 by the USGS using radar techniques. The
data has not yet been published but verbal communication
with the USGS staff has indicated that the ice depth is
probably 500-600 feet in the lower moraine covered part
of the glacier near the lake outlet. Thus it would
appear that the outlet channel from the lake may be a
small gravel and boulder lined notch in a deep bed of
moving ice that does not provide a suitable foundation
for a permanent structure.
Chakachatna Dam
The possibility of gaining both storage and head by means
of a dam on the Chakachatna River was first posed in 1950
by Arthur Johnson (Johnson, 1950) who identified, though
was unable to inspect, a potential dam site about 6 miles
downstream from the lake outlet. Three years later,
during the 1953 eruption of Mount Spurr, a mud flow
descended the volcano slopes and temporarily blocked the
river at this location, backing it up for about 4-miles
until it overtopped the debris dam. At this location,
the river today is still backed up almost 2 miles despite
the occurr~nce of the August 1971 lake breakout flood
estimated to have peaked at about 470,000 cubic feet per
second (Lamke, 1972). This flow is about twenty times
larger than the maximum daily discharge that occurred
during the 1959-1972 period of record.
3-2
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Examination of aerial photographs taken after the 1953
eruption between 1954 and 1981 indicate that subsequent
mud flows, though of smaller magnitude, may have occurred
but probably did not reach the river. The source of this
activity has been Crater Peak, an active volcanic crater
on the southerly flank of Mount Spurr. It lies directly
above and in close proximity to the postulated dam site
and thus poses serious questions on the safety of this
site for construction of any form of dam. At this
location, generally from about 6-miles to 7-miles
downstream from the lake outlet, the river is confined
within a canyon. Both upstream and downstream, the
valley substantially widens and does not appear to offer
any topographically feasible sites for locating a dam.
Within the canyon section itself, conditions are rather
unfavorable for siting a dam. Bedrock is exposed on the
right abutment, making this the most likely site for a
spillway, but the rock surface dips at about 40-degrees
toward the river channel~~ At this location, the peak
discharge of the probable maximum flood calculated
according to conventional procedures would be in the
order of 100,000 cubic feet per second. The flood of
record however, is estimated to have peaked at about
470,000 cubic feet per second (Larnke, 1972). It was
apparently caused by a sudden release of stored water
from Chakacharnna Lake when a part of the toe of the
Barrier Glacier, that was constricting the outlet
channel, was eroded away. Since the repetition of such
an event would still be possible in the future, even if a
dam were constructed so that its reservoir water level
exceeded that of the present lake level, the discharge
capacity of a spillway at this location would apparently
have to be at least equal to the 470,000 cubic feet per
second flood of record. The crest length of such a
3-3
spillway would have to be several hundred feet and sit-
ing it on the steeply dipping right abutment rock sur-
face would be difficult and very costly. It is clearly
evident that the problems associated with designing a
spillway of these proportions on such a steeply dipping
rock surface are very serious indeed.
Surface examination of the left abutment conditions, as
discussed in Section 5.2.3.2 of this report, indicates
that they consist of deep unconsolidated volcanic ma-
terials. These would require a deep diaphragm wall or
slurry trench cutoff to bedrock, or an extensive up-
stream foundation blanket to control seepage through
the pervious materials lying on this abutment. Very
high costs would also be attached to their construc-
tion.
The presence of the volcano and its potential for fu-
ture eruptions accompanied by mud flows as well as
pyroclastic ash flows is probably the overriding factor
in discrediting the feasibility of constructing a dam
in this canyon location. Consequently, pending further
examination next year, this concept has been temporari-
ly set aside from further consideration at the present
stage of the studies, and the main thrust has been di-
rected toward development by gaining regulatory star-
age by drawing down the lake water level and diverting
water from a submerged intake in Chakachamna Lake
through a tunnel to the McArthur River, or through a
tunnel to the mouth of the Chakachatna Valley, as dis-
cussed in the next two sections of this report.
3-4
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3.3
3.3.1
McArthur Tunnel Development
Alternative A
Initial studies have been directed toward development by
means of a tunnel to the McArthur River that would
maximize electrical generation without regard to release
of water into the Chakachatna River for support of its
fishery. Two arrangements have been studied, the first
being a tunnel following an alignment about 12-miles long
designated Alternative A-1 and shawn in Figure 3-1. This
alignment provides access for construction via an adit in
the Chakachatna Valley about 3 miles downstream from the
lake outlet. As discussed in Section 9.0 of this report,
the tunnel would be 25-feet internai diameter and
concrete lined throughout its full length.
The second tunnel studied is designated Alternative A-2
and follows a direct alignment to the McArthur Valley
without an intermediate access adit as shawn on Figure
3-2. As further discussed in Section 9.0 of this report,
this tunnel would also be 25-feet diameter and concrete
lined.
Although the tunnel for Alternative A-l is about 1-mile
longer than that for Alternative A-2, it would enable
tunnel construction to proceed simultaneously in four
headings thus reducing its time for construction below
that required for the shorter tunnel in Alternative A-2.
Nevertheless, the studies show that the economies favor
the shorter tunnel and no ether significant factors that
would detract from it have been identified at this stage
of the studies. Therefore the direct tunnel route was
adopted and all further references in the report to
Alternative A are for the project layout with the direct
tunnel shawn on Figure 3-2.
3-5
Typical sketches have been developed for the arrangement
of structures at the power intake in Chakachamna Lake and
these are shown on Figure 3-4 with typical sections and
details on Figure 3-5. Similarly, layouts have been
developed for structures located beyond the downstream
end of the tunnel. These include a surge shaft,
penstock, manifold, valve gallery, powerhouse,
transformer gallery, access tunnel, tailrace tunnel and
other associated structures as shawn on Figure 3-6.
For Alternative A, the installed capacity of the
powerhouse derived from the power studies discussed in
Section 4.0 of this report is 400 MW. For purposes of
estimating costs, the installation has been taken as four
lOO MW capacity vertical shaft Francis turbine driven
units.
It is to be noted that the layout sketches mentioned
above and those prepared for other alternatives
considered in this report must be regarded as strictly
typical. They form the basis for the cost estimates
discussed in Section 8.0 but will be subject to
refinement and optimization as the studies proceed. For
example, the lake tapping for the power intake is laid
out on the basis of a single opening about 26-feet in
diameter. This is a very large underwater penetration to
be made under sorne 150-170 feet of submergence, and the
combination of diameter and depth is believed to be
unprecedented. In the final analysis, it may prove
advisable to design for multiple smaller diameter
openings. The information needed to evaluate this is not
available at the present time.
3-6
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In similar vein, the penstock is shown as a single
inclined pressure shaft descending to a four-branched
manifold at the powerhouse level with provisions for
emergency closure at the upstream end. Again, this is a
very large pressure shaft, but the combination of
pressure and diameter is not unprecedented in sound
rock. Other considerations, such as unfavorable
hydraulic transients in the manifold,or operational
flexibility,may support the desirability of constructing
a bifurcation at the downstream end of the tunnel with
two penstocks, each equipped with an upper level shutoff
gate, provided to convey water to each pair of turbines
in the four-unit powerhouse. Such an arrangement would
cost more than the single penstock shaft.
Turbine shutoff valves are shown located in a valve
chamber separated from the powerhouse itself.
Optimization studies will be made during 1982 to evaluate
whether these valves can be located inside the powerhouse
at the turbine inlets, or whether a ring gate type
installation inside the turbine spiral cases might be
preferable.
The powerhouse is shown as an underground installation.
This appears to be the most logical solution for
development via the McArthur River because of the steep
avalanche and rock slide-prone slopes of the canyon
wall. For the same reason, the transformers are shown in
a chamber adjacent to the powerhouse cavern. A surge
chamber is shown near the upstream end of the tailrace
tunnel. It may prove more advantageous for this
relatively short tailrace tunnel to make it free-flowing
in which case the surge chamber would not be required.
3-7
3.3.2
The object of the above comments is to point out sorne of
the options that are available. The arrangement of
structures shown provides for a workable installation.
In the present short time frame since the study began,
it is not to be regarded as the optimum or most economi-
cal. Optimization will be performed at a later date.
The layout is a workable arrangement that gives a rea-
listic basis on which to estimate the cost of construct-
ing the project, and a separately identified contingency
allowance is provided in the estimate to allow for costs
higher than those foreseen at the present level of study.
Alternative B
This alternative considers what effect a tentative allo-
cation of water to meet instream flow requirements in
the Chakachatna River would have on the amount of energy
that could be generated by Alternative A which would use
all stored water for energy generation. The tentative
instream flow schedule is discussed in Section 7.3.2 of
this report. For diversion to the McArthur River, and
reservation of water for instream flow releases, the
tunnel diameter would be about 23 feet. Based on the
power studies discussed in Section 4.0, the installed
capacity of the powerhouse would be reduced to 330 ~~
The tunnel alignment and basic layout of structures
generally is the same as that shown for Alternative A in
Figure 3-2. The diameters of hydraulic conduits and the
dimensions of the 330 MW powerhouse would be smaller
than for the 400 MW powerhouse in Alternative A and ap-
propriate allowances for these are made in the cost es-
timates.
3-8
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----"·-~~---~~~~-"11~~~_,_=~-ff"~"'~""'""~-,,.~--..~ ... -=--
3.4
3.4.1
The actual manner in which water would be released to the
Chakachatna River is not presently identified. In any
plan of development that includes the provision of an
adit 3 miles downstream from the lake outlet, as
mentioned in Section 3.3.1 above, the adit would be a
convenient point of release for the water. This,
however, would not replenish any flow in the first 3
miles of the river, and nor would it keep the lake outlet
open for either upstream or downstream passage of fish.
In fact, keeping the lake outlet open bears every
indication of being a very difficult problem to solve,
and from a practical point of view may not be readily
soluble unless the operating range of lake level is kept
within narrow limits. That of course would adversely
affect the amount of energy that could be generated by
the project and possibly even destroy its viability. Due
to the presence of the glacier at the lake outlet, it
would appear that any fish passage facility would have to
be constructed inside a tunnel in the right bank which is
a massive rock mountainside. Since no plan for such a
facility has been developed at this stage of the studies,
a provisional allowance of $50 million is shown in the
estimate for fish passage facilities.
Chakachatna Tunnel Development
Alternative C
The initial studies of this Alternative focused on
development of the power potential by means of a tunnel
roughly paralleling the Chakachatna River without release
3-9
of water for instream flow requirements between the lake •
outlet and the powerhouse where the water diverted for
power generation would be returned to the river. The
tunnel alignment is shown on Figure 3-3.
This alignment offers two convenient locations for
intermediate access adits during construction. The first
is about 3 miles downstream from the lake outlet in the
same location as discussed in Section 3.3.1 above for
Alternative A. The second adit location is about 7 miles
downstream from the lake outlet. The total tunnel length
in this arrangement is about 12 miles and the adits would
make it possible for construction of the tunnel to
proceed simultaneously in six different headings.
The arrangement of the power intake is essentially the
same and in the same location as for Alternative A as
shown on Figures 3-4 and 3-5. The tunnel is also 25-feet
internal diameter, concrete lined, and penetrates the
mountains in the right wall of the Chakachatna Valley.
The arrangement for the surge shaft, penstock, valve
gallery, powerhouse and associated structures is similar
to that for development via diversion to the McArthur
River but is modified to fit the topography and lower
head. The layout is shown on Figure 3-7. The head that
can be developed in Alternative C is roughly 200 feet
less than in Alternatives A and B and the installed
capacity in the powerhouse is only 300 MW as determined
from the power studies discussed in Section 4.0 of this
report.
For purposes of estimating the present costs of
construction, the powerhouse is taken as being located
underground. If economy can be attained by locating it
3-10
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outside on the ground surface, this will be optimized in
subsequent studies. Comments made in Section 3.3.1
regarding the layout sketches for the McArthur powerhouse
in Alternative A apply equally to the powerhouse and
associated structures for the Chakachatna powerhouse
considered in Alternative C.
Alternative D
Studies of this Alternative take account of the effect on
electrical generation of reserving water to meet instream
flow requirements in the Chakachatna River. The
tentative water release schedule is less than that
considered for development by power diversions to the
McArthur River as discussed in Section 7.1.5 of this
report. The reason for this is that in the lower reaches
of the river, downstream from the proposed powerhouse
location, the river flow will include those waters that
were diverted for electrical generation. These lower
reaches of the river are probably more important to the
fishery than the reach of the river between the lake
outlet and the proposed powerhouse location. This
probability is suggested, though not fully confirmed, by
observations made of fish runs during the 1981 field
studies. These have indicated that the Chakachatna
River, between the lake outlet and the proposed location
of the powerhouse, serves primarily as a travel corridor
for fish passing through the lake to spawning areas
further upstream. The river itself, in this reach does
not appear to offer much in the way of suitable spawning
and juvenile rearing habitat. On the other hand,
significant numbers of fish and spawning areas were
observed in the lower reaches of the river downstream
from the proposed powerhouse location. Consequently, the
3-11
3.5
tentative instream flow releases are small when compared
with those considered for development via power
diversions to the McArthur River, as discussed in Section
7.1.5 of this report. The tunnel diameter for
development of the power potential via the Chakachatna
tunnel with provision for instream flow releases, is
25-feet, the same as that mentioned in Section 3.3.1
above without such releases. The installed capacity in
the powerhouse also remains the same at 300 MW. The
layout sketches shown in Figures 3-3 and 3-7 for
Alternative C are equally applicable to Alternative D as
are the comments set forth in Section 3.3.0 regarding the
layout sketches for development via the McArthur River.
Transmission Line and Submarine Cable
At the present stage of the project development studies,
no specifie evaluation has been made of transmission line
routing. Whether development should proceed via the
proposed McArthur or Chakachatna powerhouse locations, it
is assumed for the purposes of the cost estimates that
the transmission lines would run from a switchyard in the
vicinity of either powerhouse site to a location in the
vicinity of the existing Chugach Electric Association's
Beluga powerplant. The general routing of the proposed
lines is shown on Figure 3-8. At Beluga, an inter-
connection could be made through an appropriate switching
facility with the existing Beluga transmission lines if a
mutually acceptable arrangement could be negotiated with
the owners of those lines. This would enhance reliability
of the total system, but for purposes of this report no
such interconnection has been assumed.
3-12
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3.6
Beyond Beluga, it is assurned for purposes of the
estirnate, that the new transmission lines for the
Chakachatna or McArthur powerhouses would parallel the
existing transmission corridor to a terminal on the
westerly side of Knik Arrn and cross that waterway by
subrnarine cables to a terminal on the Anchorage side.
Beyond that point, no costs are included in the estimates
for any further required power transmission installations.
In the four alternatives thus far considered, the cost
estimates are based on power transmission via a pair of
230 KV single circuit lines with capacity matching the
peaking capability of the respective power plants.
Optimization studies to determine whether transmission
should be effected in that manner or by a single line of
double circuit towers are planned to be performed during
1982.
References
Giles, Gordon c., April 1967.
Barrier Glacier Investigations and Observations in
Connection with Water Power Studies. USGS rough draft
report.
Jackson, Bruce L., March 1961. Potential Water Power
of Lake Chakachamna, Alaska. USGS open file report.
Johnson, Arthur, January 1950. Report on Reconnaissance
of Lake Chakachamna, Alaska, USGS •
3-13
Lamke, Robert, March 1972, Floods of the Summer of 1971 in
South-Central, Alaska. USGS open file report.
United States Bureau of Reclamation, 1952.
Reconnaissance Report on the Potential Development of
Water Resources in the Territory of Alaska.
United States Bureau of Reclamation, 1962.
Chakachamna Project, Alaska. Status Report.
United States Department of the Army, Corps of Engineers,
1950. Survey Report on Harbors and Rivers in Alaska.
Interim Report No. 2, Cook Inlet and Tributaries.
3-14
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....,.)
-
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.,.
•
HYDROLOGICAL
AND
POWER STUDIES
------------------------------------':' ,.,.,,.., ........,.,....,...., -t:1t li:>IO~ ~""'~~--------------
4.0
;
4.1
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-
HYDROLOGICAL AND POWER STUDIES
Introduction
River flow records from a gaging station are usually
accepted as an indicator of future runoff from a drainage
basin and the longer the period of record is, the more
reliable it will be in forecasting future runoff. In the
case of Chakachamna Lake, the records of a gage located
near the lake outlet caver only a relatively short period
of time from June 1959 to September 1972. Furthermore,
sorne gaps that occurred during the above period further
reduce its continuity to a period dating from June 1959
to August 1971.
There are no records of the inflow to Chakachamna Lake,
and since that information is needed to perform reservoir
operation and power studies, the inflows were calculated
for the continuous period of record by reverse routing
the outflows and making appropriate adjustments for
changes in lake water levels.
Continuing efforts are being made to extend the
hydrological data base by statistical correlation with
records from other stations. An encouraging relationBhip
has emerged but was not ready in time to be used for this
interim report. Consequently, the inflows derived from
the existing records have been used in the studies to
determine the power generating potential of the water
resource in the Chakachamna basin.
4-1
4.2 Historical Data
Hydrometeorological data from several stations in the
Cook Inlet Basin are being used for the derivation and
extension of estimated lake inflow records. Streamflow
records include the following furnished by u.s.
Geological Survey:
Station No.
15294500
15284000
15284300
15292000
Description
Chakachatna Rivet near Tyonek
(the lake outlet gage)
Matanuska River near Palmer
Skwentna River near Skwentna
Susitna River at Gold Creek
-
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~
Gaging Station No. 15294500 above is located on the right ~
bank of the Chakachatna River close to the outlet of
Chakachamna Lake. The gage records extend for 13 years
and 5 months from May 21, 1959 to September 30, 1972.
The gage however, was rendered inoperative by a lake
outbreak flood on August 12, 1971 and the records between
that date and June 20, 1972 are estimated rather than
recorded flows. Thus, the true period of record only
extends from May 21, 1959 to August 12, 1971 and from
June 20, 1972 to September 30, 1972. Furthermore, during
that period, several of the winter month flows are
estimated figures because of icing conditions and
instrument failure. This however, is not considered to
be a serious concern, because only 11% of the average
annual flow has occurred in the seven months from
November through May.
4-2
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....
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In addition to the streamflow data, records of the water
surface elevation at Station No. 15294500 were also
obtained from USGS files.
Meteorological data consist of daily temperature and
precipitation data furnished by National Oceanic and
Atimospheric Administration, National Climatic Center,
Ashville, N.C. for the following stations:
Kenai
Anchorage
Sparrevohn
The locations of all stations mentioned above are
indicated on Figure 4-1. A bar chart showing the periods
of record at these stations is plotted on Figure 4-2.
Deiived Lake Inflows
Chakachamna Lake with its surface area of about 26-square
miles regulates the runoff from its drainage basin to a
moderate extent. In order to derive a record of inflows
to the lake, the regulatory efforts of the lake were
\
removed from the outflow records by a reverse routing
procedure which is basically a water balance computation
using the classic continuity equation set forth below:
It -Ot = ~s
Where
It is the inflow volume during month t
ot is the outflow volume during month t
~s is the change in lake storage during month t
4-3
4.4
For all practical considerations, the Chakachatna River
near Tyonek gage is, in effect, located at the lake
outlet and field observations confirmed that its height
closely represents the lake water surface elevation.
Hence, it was assumed for the reverse routing
computations that the two were the same. Evaporation,
seepage and ether lasses of water from the lake were
assumed to be small and effectively compensated for by
direct precipitation onto the lake surface, the latter
being otherwise ignored.
The lake stage-storage curve used in the computations is
shawn on Figure 4-3. This is based on data measured by
the USGS and recorded on maps Chakachatna River and
Chakachmna Lake Sheets 1 and 2 dated 1960.
The average monthly inflows were calculated for the
period June 1, 1959 through July 31, 1971. The eleven
calendar years from January 1, 1960 to December 31, 1970
were used as the basis for power studies and the inflows
for this period are listed in Table 4-1 from which it may
be noted that the mean annual i~flow was 3,547 cubic feet
per second.
Power Studies
Using the derived lake inflows mentioned above,
powerplant operation studies were performed to determine
the firm and secondary energy, the power flows and the
fluctuations in the water surface elevation of
Chakachamna Lake for a range of installed capacities in
each of the four alternative forms of project development
described in Section 3.0 of this report. The studies
were made by means of a computer program that performs
sequential routing of the derived monthly inflows while
4-4
i -
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-
-
'-
-
-
-1
-
--------------------------------=-----------
satisfying power demands, the tentative in-stream flow
requirements, and physical system constraints. Power
demands are in accordance with a plant load factor of 0.5
and the monthly variations in peak demand listed in
Table 4-2. As advised by APA, these have the same values
as those being used in the evaluation of sources of power
alternative to that of the Chakachamna Hydroelectric
Project.
The in-stream flow requirements, listed in Table 4-3,
represent provisional minimum monthly flows to be
released into the Chakachatna River near the lake outlet
as further discussed in Sections 7.3.2 and 7.3.3 of this
report.
The physical system constraints, set forth in Table 4-4,
are the overall plant efficiency, tailwater elevation and
head loss coefficient for the hydraulic conduits.
The power studies were performed in such manner that
water was drafted from lake storage whenever the monthly
inflows were insufficient to meet the power demqnd. On
the assumption that spill, or discharge of water from the
lake into the Chakachatna River in excess of the
tentative instream flow requirements would occur from the
natural lake outlet whenever the lake water level
exceeded elevation 1,128 feet, the amount of secondary
energy that could be generated was also calculated. The
secondary energy, is that which can be generated by plant
capacity in excess of that needed to meet the load
carrying capability, using water which otherwise would
have spilled.
4-5
,j::o.
1
0'\
Year
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
Mean
Jan. Feb.
400. 307.
877. 589.
633. 541.
498. 357.
364. 435.
419. 219.
388. 336.
531. 449.
534. 510.
465. 486.
497. 504.
511. 430.
-----
TABLE 4-1
DERIVED INFLOWS TO CHAKACHAMNA LAKE
Mar. Apr. May June July Aug. Sept.
Flow in cubic feet per second
267. 393. 3637. 6837. 11209. 9337. 3145.
470. 346. 1981. 7983. 12808. 10899. 6225.
471. 470. 1265. 7925. 13149. 10411. 5542.
315. 337. 1801. 4735. 13249. 12208. 5847.
332. 477. 1830. 8093. 10700. 11798. 4246.
337. 398. 1286. 3490. 13046. 10516. 10802.
350. 410. 1893. 8072. 10303. 9974. 6608.
384. 880. 2030. 8761. 14931. 15695. 6191.
467. 630. 2996. 7808 •• 13117. 11257. 2793.
500. 652. 1948. 9271. 12510. 7297. 2793.
550. 899. 2265. 6789. 10360. 7986. 2734.
404. 536. 2076. 7251. 12307. 10671. 5175.
---------------··--·---------~-~ -----
t L l, 1 ~~
Oct. Nov. Dec. Mean
1439. 799. 870. 3220.
1586. 843. 696. 3767.
1197. 863. 613. 3590.
2056. 930. 710. 3587.
1245. 909. 662. 3424.
2114. 597. 466. 3641.
1953. 910. 313. 3459.
2040. 1215. 571. 4473.
976. 689. 612. 3532.
3057. 1215. 541. 3396.
1359. 742. 460. 2929.
1729. 883. 592. 3547.
1 ( l 1. ~· ~~
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-
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TABLE 4-2
MONTHLY PEAK POWER DEMANDS USED IN POWER STUDIES
MON TH MONTHLY PEAK DEMAND
(Percent of Annual Peak Demand)
January 92
February 87
March 78
April 70
May 64
June 62
July 61
August 64
September 70
October 80
November 92
December 100
Susitna Hydroelectric Project Development Selection
Report Appendix D, Table D.l {Second Draft, July 1981)
4-7
TABLE 4-3
PROVISIONAL MINIMUM RELEASES FOR INSTREAM FLOW IN
CHAKACHATNA RIVER DOWNSTREAM FROM CHAKACHAMNA
LAKE OUTLET FOR USE IN POWER STUDIES
MONTH MC ARTHUR TUNNEL CHAKACHATNA TUNNEL
DEVELOPMENT DEVELOPMENT
ALTERNATIVE B ALTERNATIVE D
(CFS}* (CFS}
January 365 30
February 343 30
March 345 30
April 536 30
May 1;094 30
June 1,094 30
July 1,094 " 30
August 1,094 30
September 1,094 30
October 365 30
November 365 30
December 360 30
*Use the average monthly inflow to the lake (CFS) or the figure
listed whichever has the lower value.
..
4-8
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-
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ALTERNATIVE
A
B
c
D
TABLE 4-4
POWERPLANT SYSTEM CONSTRAINTS FOR
ALTERNATIVE PROJECT DEVELOPMENTS
PLANT AVERAGE HEAD LOSS IN
EFFICIENCY TAILWATER HYDRAULIC CONDUITS
(%) ELEVATION (FT.)
(FT.)
85 210 o.ooooo24 x o2
85 210 o.ooooo24 x o2
85 400 o.ooooo2a x o2
85 400 o.ooooo28 x o2
Note: Q = Flow in cubic feet per second.
4-9
4.5
For each of the alternatives considered for development
of the project, a range of installed powerplant capacities
was tested in order to determine what installed capacity
would make the most use of all water available for power
generation without drawing the lake level below a given
minimum elevation. This was tentatively taken as 1,014
feet which is about 114 feet drawdown below the reported 1 i
outlet channel invert elevation. The lake was assumed to ·~
be full at the beginning of each run.
Results
The results of the power studies listed in Table 4-5 show
that, on the basis of the 11 years of record, and with
the parameters used in the studies, the optimum
development via the McArthur Tunnel could support a
powerplant of 400 MW installed capacity when all
controlled water is used for power generation as in
Alternative A. At 50% plant factor, this provides an
average annual 1,752 GWh of firm energy. The provisional
instream flow reservations for Alternative B discussed in
Section 7.3.2 of this report represent about 19% of the
average annual flow in the Chakachatna River during the
period of record. If that amount of water is reserved
for instream flow, then the installed capacity of
powerplant that could be justified in development of the
project via the McArthur River would be reduced almost
proportionately to 330 MW and the firm average annual
energy would be 1446 GWh.
For development via the Chakachatna tunnel, the optimum
development using all controlled water for power
generation, Alternative C, would have an installed
capacity of 300 MW and the firm annual average energy is
1314 GWh at 50% plant factor. The provisional minimum
4-10
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4.6
instream flow reservations in Alternative D discussed in
Section 7.3.3 of this report represent less than 1% of
the average annual flow during the period of record.
Thus the installed capacity and firm energy in
Alternative D for practical purposes would remain the
same. There would however be about 15% reduction in the
amount of secondary energy that could be generated.
Variations in Lake Water Level
The variations in lake water surface elevation calculated
at the end of the month during the course of the power
studies for each of the four alternatives and cases
listed in Table 4-5 are plotted for ease of reference on
Figure 4-4 for Alternatives A and B, and on Figure 4-5
for Alternatives C and D.
4-11
.s::.
1
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(
TABLE 4-5
POWER STUDIES SUMMARY
Development Installed Average Annual Energy Average Annual Flow
Alternative Capacity Firm Surplus Power Diversion Provisional
A
B
c
D
Note:
(MW) (GWh) (GWh) (CFS) Instream (CFS)
400 1752 153 3322 0
330 1446 124 2701 679
300 1314 139 3230 0
300 1314 130 3239 30
Period of record January 1, 1960 Ço December 31, 1970
Average annual inflow to Chakachamna Lake 3547 cfs (2.6 million AF)
Alternatives A & B -Development via McArthur tunnel
Alternatives C & D -Development via Chakachatna tunnel
Spill
(CFS)
225
167
317
278
--"----~-------
Power diversion flows are the flows needed to meet 'firm energy requirements.
Spill is the difference between average annual inflow to Chakachamna Lake
(3547 CFS) and the sum of power diversion plus provisional instream flows.
Part of the spill can be used for the generation of surplus energy.
1 ······ t.. " [. v t J 2A42A_L0 2258.) 1 1 1 1 l ..
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GEOLOGIC INVESTIGATIONS
Scope of Geologie Investigations
Technical Tasks
The scope of the geologie investigations planned for the
Chakachamna Hydroelectric Project Feasibility Study
includes five technical tasks:
(1) Quaternary geology,
(2) Seismic geology,
(3) Tunnel alignment and powerplant site geology,
(4) Construction materials geology, and
(5) Road and transmission line geology.
These tasks were identified and scopes defined so that,
upon completion of the investigations, the information
needed to assess the potential impact of a range of
geologie factors on the feasibility of the proposed
project will be available. If the Chakachamna Project is
judged to be feasible, additional geologie investigations
will be required in ~rder to provide the detailed
information appropriate for actual design.
At the feasibility level, it is appropriate to gather
information regarding the general character of the
geologie environment in and around the project area, with
particular attention to geologie hazards and the geology
of specifie facilities siting locations. The Chakachamna
5-1
5.1.1.1
Project, as presently conceived, is unlikely to include
facilities such as dams that would incrèase the risks
associated with geologie hazards that are naturally
present in the project area. The geologie tasks were
planned in recognition of the above and were designed to
focus on geologie factors that may influence the
technical feasibility, the operating reliability, and/or
the cast of the proposed project.
The work on the geology tasks began in August 1981 but
the majority of the work will take place in 1982. This
interim report includes a summary of the work planned for
the geologie investigations (Section 5.1.1) and the
schedule for each geology task (Section 5.1.2), summaries
of the work completed for the Quaternary geology (Section
5.2) and seismic geology (Section 5.3) tasks, and sorne
preliminary commentary on geologie conditions in the
project area included in Section 7.0. The commentary and
any tentative conclusions presented here are subject to
revision as the project work continues.
Quaternary Geology
...,.ji
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The Quaternary geology task was designed to include an w
assessment of the glaciers and glacial history of the
Chakachamna Lake area, an investigation of the Mt. Spurr
and associated volcanic centers, and a study of the slope
conditions near sites proposed for project facilities.
A study of the glaciers was judged to be appropriate
because:
(1) movement of the terminus of Barrier Glacier
influences the water level in Chakachamna Lake~
5-2
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(2) the possibility that changes in the terminal
position of Blockade Glacier could alter the
drainage at the mouth of the McArthur River Canyon;
and
(3) questions regarding the influence of other glaciers
in the study area on the size and hydrologie balance
of Chakachamna Lake.
In addition, knowledge of the ages of geomorphic surfaces
is important to the assessment of possible seismic
hazards and such knowledge depends on an understanding of
the glacial geology.
The simple presence of Mt. Spurr, an active volcano, at
the eastern end of Chakachamna Lake provides a clear
rationale for investigating the volcanic history and
potential volcanic hazards of the project area. Of
particular interest is the possibility that lava flows or
volcanic mudflows (a possibility increased by the glacier
ice on Mt. Spurr) could enter the lake and produce large
waves, an increase in lake level, and/or a change in
conditions at the lake outlet or on the upper reaches of
the river. In addition, the possible impact of a dark,
heat-absorbing layer of volcanic ejecta on the glaciers~
mass balance, and thus the lake's hydrologie balance is
of interest.
Chakachamna Lake, Chakachatna River Canyon, and McArthur
River Canyon are all bordered by steep slopes that may be
subject to a variety of types of slope failure. A large
landslide into the lake could change the usable volume of
water stored in the lake and could alter conditions at
the proposed lake tap and at the natural outlet from the
5-3
5.1.1.2
lake. Potential outlet portal and surface powerhouse
sites in the river canyons are all on or immediately
adjacent to steep slopes. Both the integrity of and
access to these facilities could be impaired in the event
of landslide and rockfall activity.
Because of the concerns indicated above, the Quaternary
~
geology task was designed to investigate the timing and ~
size of past glacial fluctuations, the frequency and type
of volcanic activity, and the slope conditions in order
to provide an estimate of possible future events that
could influence the costs and operating performance of
the proposed hydroelectric project. In addition, this
task should provide information regarding the possibility
of the project destabilizing the lake outlet by producing
or allowing changes in Barrier Glacier, thereby
increasing the flood hazard.
Seismic Geology
The seismic geology of the Chakachamna Lake area is of
interest because southern Alaska is one of the most
seismically active areas in the world. Potencial seismic
~
hazards of direct concern to the proposed hydroelectric
project include surface faulting, ground shaking,
seismically-induced slope failure, lake seiche, and
liquefaction. Specifically, the seismic geology task was
designed to investigate the possibility of active faults
in the immediate vicinity of the proposed facilities, to
access the location and activity of regional faults
(e.g., Castle Mountain, Bruin Bay), and to estimate the
type and intensity of seismic hazards that may be
associated with these faults and with the subduction zone.
5-4
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5.1.1.3
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The seismic geology investigations were planned to maxi-
mize the use of existing information by following a
sequence of subtasks that become increasingly site
specifie as the work proceeds. The primary·elements in
the sequence are:
o literature review
o remote sensing imagery analysis
o field reconnaissance
o low-sun-angle air photo acquisition and analysis
o detailed field studies
The data produced by the above sequence is required to
assess directly the surface faulting hazard and for input
to the probabilistic assessment of ground motion para-
meters.
In order to develop approximate ground motion spectra for
the various elements of the project, existing ground
motion information developed for other projects in
southern Alaska will be reviewed and modified, as
appropriate. A simplified evaluation of the liquefaction
potential of the transmission line alignment is also
planned.
Tunnel Alignment and Powerplant Site Geology
The scope of work for this task was based on the need to
assess the feasibility of constructing a lake tap in
Chakachamna Lake, a long tunnel, and a powerhouse as the
5-5
5.1.1.4
primary components of the proposed hydroelectric
development. Because of the steep mountainous terrain
above the tunnel alignment, the tunnel feasibility study
was planned around the mapping of bedrock exposures in
the mountains and production of a strip map; drilling
will be limited to the powerhouse site during the feasi-
bility investigations. The strip map will focus on those
bedrock characteristics that determine the technical and
economie feasibility of tunnelling. Geophysical techni-
ques will be used to assess the lake bottom bedrock and
sediment characteristics at and near the proposed lake
tap and subsurface conditions at the proposed powerhouse
site.
All reasonably possible surface powerplant and outlet
portal sites are on or adjacent to high, steep slopes.
Hazards such as landslides, rockfalls, and avalanches,
which are a particular concern in seismically active
areas, will also be assessed during the feasibility study.
Construction Materials Geology
The proposed Chakachamna Hydroelectric Project will, if
constructed, require aggregate for concrete, road con-
struction, and construction of the transmission line. In
addition, boulder rip-rap may be required at the outlet
portal and outfall from the powerhouse. This task was
planned to yield information about potential aggregate
sources at the powerhouse-outlet portal site, along the
road, and along the-transmission line alignment.
5-6
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5.1.2
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5.1.2.1
.....
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Road and Transmission Line Geology
Geologie considerations will be important in the
assessment of the road and transmission line routes~
This task was designed to use aerial photograph analysis
and reconnaisdance-level field studies in order to
provide information on the general character of the
alignments. The task plans recognized the need to give
particular attention to river crossings, which may be
subject to large floods, and to wetland areas where
special construction techniques may be required.
Schedule
Because 1981 field work could not begin until late August
and because the details of sorne of the geologie field
work are appropriately a function of the decisions
reached during ether, non-geologie tasks, the 1981
geologie field program was limited.
Quaternary Geology
All of the Quaternary geology field studies were either
of a regional nature or directed at targets that would
not vary as a function of final configuration of the
project facilities. Therefore, it was possible to
complete the field work planned for this task. Sorne
additional review of unpublished data, such as that held
by the u.s. Geological Survey in Fairbanks, and
discussions with geologists who have worked in the
Chakachamna area remain to be completed. Although
several important implications with respect to the
proposed hydroelectric project have been identified and
5-7
5.1.2.2
5.1.2.3
5.1.2.4
sorne tentative conclusions may be drawn, additional
analyses and discussions are needed before the
conclusions can be finalized.
Seismic Geology
As discussed in Section 5.1.1.2, the seismic geology task
is designed around a sequence of investigations, each of
which builds on the preceding ones. Because of this
characteristic, the seismic geology task demands a
certain amount of elapsed time and cannot be speeded up
by adding additional staff.
During 1981 it was possible to complete the lite.rature
review, analysis of existing remote sensing imagery,
field reconnaissance, and the acquisition and initial
analysis of the low-sun-angle aerial photography. The
detailed field studies and ground motion assessment will
be conducted in 1982.
Tunnel Alignment and Powerplant Site Geology
No field investigattons were conducted for this task in
1981 because the various tunnel alignment locations and
configurations to be studied were not identified prior to
completion of the 1981 field season. All of the geologie
and geophysical investigations planned for this task will
be completed in 1982.
Construction Materials Geology
The work for this task will be conducted in 1982.
5-8
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Road and Transmission Line Geology
The work for this task will be conducted in 1982.
Quaternary Geology
The Quaternary, approximately the last 2 million years of
geologie time, is commonly subdivided into the
Pleistocene and the Holocene (most recent 10,000 years).
Although the Pleistocene is generally equated to the
glacial age and the Holocene with post-glacial time, such
a distinction is less clear in southern Alaska where the
mountains still contain extensive glaciers.
The Quaternary was a time of extreme and varied geologie
activity in southern Alaska. In addition to the
extensive glacial activity and associated phenomena, the
Quaternary was also a time of mountain building and
volcanic activity. The products of these and other
geologie processes that were active during the
Quaternary, and àre still active today, are broadly
present in the Chakachamna Lake area. Although the
geologie investigations for this feasibility study
consider a bread range of topics that fall under the
general heading of Quaternary geology, this task was
planned to address three specifie topics:
(1) glaciers and glacial geology;
{2) Mt. Spurr volcano; and
(3} slope conditions.
5-9
5.2.1
5.2.1.1
In addition, the seismic geology task (Section 5.3) is
designed to focus on Quaternary and historie fault
activity and seismicity and is highly dependent on an
understanding of the glacial history of the area for
temporal data.
For the Quaternary geology task of the Chakachamna
....&/
feasibility study, field work consisted of a twelve-day ~
reconnaissance during which all three primary tapies of
interest (above) were studied. When combined with
information available in the open literature and that
gained through interpretation of aerial photography, the
field reconnaissance provides a basis for assessing the
potential impact of the glaciers, volcano, and slope
conditions on the proposed hydroelectric project.
Glaciers and Glacial Geology
Regional Glacial Geologie History
At one time or another during the Quaternary, glaciers
covered approximately half of Alaska (Pewe, 1975).
Pr~vious investigations have demonstrated that the Cook
Inlet region has had a complex history of multiple
glaciation (Miller and Dobrovolny, 1959; Williams and
Ferrians, 1961; Karlstrcm, 1964; Karlstrom and others,
1964; Trainer and Waller, 1965; Pewe and others, 1965;
Schmoll and others, 1972) • The current understanding of
the region's glacial history is based on interpretation
of the morphostratigraphic record in association with
relative and absolute age dating and other Quaternary
studies. The complex history is recorded in glacial,
fluvial, lacustrine, marine, and eolian sediments that
have been studied primarily in their surface exposures
5-10
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where they can be associated with specifie landforms.
Although more recent work has lead to modification and
refinement of Karlstrom's (1964) history of glaciation in
the Cook Inlet region, that work still provides a good
general overview and, except where noted, serves as the
basis for the following summary.
On at least five separate occasions during the
Quaternary, the glaciers in the mountains that surround
Cook Inlet have expanded onto the Cook Inlet lowlands
where they coalesced to cover rouch or all of the lowland
with ice. Evidence for the two oldest recognized
glaciations (Mt. Susitna, Caribou Hills) consists
dominantly of erratic boulders and scattered remanants of
till at high elevation sites around the margins of the
lowland. Evidence for the next glaciation, the Eklutna,
includes moraines and till sheets that demonstrate the
coalescence of ice from various source areas to form a
Cook Inlet piedmont glacier. The available evidence~
suggests several thousand feet of ice covered virtually
all of the Cook Inlet lowland during these early
glaciations.
The next two glaciations, the Knik and the Naptowne,
'correspond to the Early Wisconsin and Late Wisconsin
glaciations of the midwestern United States,
respectively. Thus, the Naptowne glaciation of the Cook
Inlet region correlates, in general, with the Donnely
(Pewe, 1975) and McKinley Park (TenBrink and Ritter,
1980; TenBrink and Waythomas, in preparation) glaciations
reported from two areas on the north side of the Alaska
Range. During the Knik and Naptowne glaciations ice
again advanced onto the Cook Inlet lowland, but the ice
did not completely cover the lowland as it apparently did
5-11
during the earlier glaciations. Even at the glacial
maxima, portions of the lowland were ice free; such areas
were commonly the sites of large ice-dammed lakes that
have been studied in sorne detail (Miller and Dobrovolny,
1959; Karlstrom, 1964}.
The maximum ice advance during the Naptowne glaciation is
recorded by distinct end moraine complexes located near
the mouths of the major valleys that drain the Alaska
Range and by moraines on the Kenai lowland. The moraines
on the Kenai lowland are of particular interest because
they were, at least in part, formed by the Trading Bay
ice lobe, which originated in the Chakachatna-McArthur
rivers area and advanced across Cook Inlet at the time of
the Naptowne maximum. Karlstrom (1964) reported on these
features on the Kenai lowland in sorne detail.
Karlstrom (1964) used a combination of radiocarbon dates
and relative-age dating techniques to develop a
chronoloqy for the Cook Inlet glaciations. According to
Karlstrom, the Naptowne glaciation continued, although
with decreasing intensity, past the Pleistocene-Holocene
boundary (generally taken as being near 10,000 years
before present [ybp]), through the Climatic Optimum, to
the beginning of Neoglaciation (see Porter and Denton,
1967) • Recent work on the north side of the Alaska Range
has produced a well-dated chronology for the McKinley
Park glaciation (TenBrink and Ritter, 1980; TenBrink and
Waythomas, in preparation). That chronology shows major
stadial events at:
(1) 25,000-17,000 ybp (maximum advance at about 20,000
ybp};
5-12
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(2) 15,000-13,500 ybp:
(3) 12,800-11,800 ybp: and
(4) 10,500-9,500 ybp.
Recognizing the differences in ice extent and other
factors between the Cook Inlet region and the north side
of the Alaska Range, the TenBrink chronology is probably
reflective of the timing of the primary Naptowne stadial
events. Dates from the Cook Inlet region proper have yet
to yield such a clear picture, probably because of the
greater complexity of the conditions and thus the record
there.
Following the Naptowne glaciation (about 9,500 ybp by
TenBrink's chronology, as late as 3,500 ybp according to
Karlstrom, 9164) , glacial advances in the Cook Inlet
region have been limited to rather small-scale
fluctuations that have extended only up to a few miles
beyond present glacier termini. Karlstrom (1964)
referred to these Neoglacial advances as the Alaskan
glaciation, which he divided into two distinct periods of
advance (Tustumena and Tunnel) and further subdivided
into three and two short-term episodes, respectively.
According to Karlstrom (1964) these Neoglacial events
range in age from approximately 3,500 ybp to historie
fluctuations of the last several decades.
Two points of particular interest regarding Neoglaciation
in Alaska emerged from the literature review:
5-13
5.2.1.2
(1) the idea that " ••• the youngest major advance
typica11y was the most extensive of the
Neog1aciation" (Porter and Denton, 1967, p. 187), and
(2) Kar1strom's (1964) suggestion that, at least in the
mountains around the margins of the Cook In1et
region, there was no distinct hiatus between the
last sma11 Naptowne readvance and the first
Neoglacial advance.
These points will be addressed in the following section.
Project Area Glacial Geologie History
The reconnaissance-leve! investigations conducted for the
Chakachamna feasibility study confirm the general picture
for the project area presented by Karlstrom (1964). The
area examined during the field reconnaissance is
indicated on Figure 5-l. Although a rather broad area
was included in the study area, most of the field work
took place in the Chakachamna Lake basin, along the
Chakachatna River, and on the southern slopes of Mt.
Spurr.
Most of he study area was covered by glacier ice during
the maximum stand of the Naptowne-age glaciers. Based on
Karlstrom's (1964) work, it would appear that only high,
steep slopes and local elevated areas were not covered by
Naptowne ice. Within the area examined in the field, the
upper limit of Naptowne ice is generally clearly defined,
particularly in the area between Capps Glacier and
Blockade Glacier, at and east of the range front (Figure
5-l). In this area lateral moraines produced during the
maximum stand of Naptowne ice (25,000-17,000 ybp) are
5-14
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--~· -----------·
distinct and traceable for long distances: younger
Naptowne lateral and terminal moraines are also present.
The largest area that was not buried by Naptowne ice and
which was observed during field reconnaissance is located
high on the gentle slopes east of Mt. Spurr, between
Capps Glacier and Straight Creek. The two older surfaces
(Knik and [?] Eklutna) observed in this area (Figure 5-l)
correspond well to the ideas presented by Karlstrom
(1964).
Not only are moraines marking the Naptowne maximum
present, but a l.arge number of moraines produced dur ing
subsequent stadial advances or recessional stillstands
are also present. These features demonstrate that even
at the Naptowne maximum, ice from Capps Glacier and other
glaciers to the north did not coalesce with ice coming
from the Chakachatna canyon, except possibly near the
coast. The Chakachatna ice and that issuing from the
McArthur River Canyon and Blockade Glacier did join,
however, to produce Karlstrom's (1964) Trading Bay ice
lobe. That ice lobe covered the alluvial flat that, at
the coast, extends from Granite Point to West Foreland.
From the present coast, the Trading Bay lobe (according
to Karlstrom, 1964) extended across Cook Inlet to the
Kenai lowland.
The complex of moraines located between Blockade Glacier
and the Chakachatna River area allow one to trace the
slow retreat of Naptowne ice. As the Trading Bay lobe
retreated westward across the inlet and then across the
Trading Bay alluvial flats to the mountain front,
separate ice streams became distinct. As the Naptowne
ice continued to retreat up the Chakachatna Canyon more
and more individual glaciers became distinct from one
5-15
another. For example, Brogan Glacier (informa! name,
Figure 5-l) , separated from the Chakachatna River by a
low volcanic ridge, produced a recessional sequence that
is independent of that formed by ice in the Chakachatna
canyon. Such a sequence of features is less distinct or
absent for the other glaciers between Brogan Glacier and
Barrier Glacier.
Within the Chakachamna Lake basin, the evidence of
Naptowne and older glaciations is largely in the form of
erosional features and scattered boulders. Naptowne-age
till apparently occurs only in isolated pockets within
the lake basin and its major tributary valleys. The
Naptowne-age surfaces in the basin are mantled with a
sequence of volcanic ashes that averages two to three
feet in thickness. The solids are typically developed on
these volcanics rather than on the underlying
glacially-sooured granitic bedrock or till.
In contrast to the erosional topography that
characterizes the Naptowne and older surfaces within the
Chakachamna Lake basin, Neoglacial activity produced
prominent moraines and outwash fans. Neoglacial features
' were examined at or near the termini of the following
glaciers:
(1) all glaciers along the south shore of the lake from
Shamrock Glacier to the lake outlet;
(2) Barrier Glacier;
(3) Pothole and Harpoon Glaciers, where they enter the
Nagishlamina River Valley;
5-16
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(4} all of the glaciers that flow to the south,
southeast, and east from the Mt. Spurr highland
(Alice Glacier to Triumvirate Glacier, Figure 5-l};
and
(5} Blockade Glacier.
The Neoglacial history of several of these glaciers is
discussed in more detail in Sections 5.2.1.3 through
5.2.1.5. The Neoglacial record is of particular
importance to an assessment of possible glacier
fluctuations over the next several decades.
Returning to the two points raised at the end of Section
5.2.1.1:
(1) In most cases observed in the study area, it appears
that the latest Neoglacial advance was as extensive
or more extensive than earlier Neoglacial advances.
This is in agreement with the Porter and Denton
(1967) general conclusion for soùthern Alaska.
(2) Karlstrom's {1964) chronology suggested a continuous
sequence of decreasing glacial advances leading from
Naptowne to Neoglacial time. In most parts of the
study area it was not possible to assess this
suggestion. However, the morainal sequence produced
by Brogan Glacier (Figure 5-l) and the difference in
the topographie characteristics of those moraines
suggest that there was little, if any, hiatus
between the youngest Naptowne moraine and the oldest
Neoglacial moraine.
5-17
5.2.1.3 Barrier Glacier
Barrier Glacier originates in the snow and ice field high
on the slopes of Mt. Spurr. From there it flows down a
steep, ice-carved canyon to the shore of Chakachamna Lake
where its piedmont lobe forms the eastern end of the lake
(Figure 5-2). Barrier Glacier is of particular interest
to this feasibility study because the glacier forms the
eastern end of the lake and influences the size and
character of the outlet from the lake.
Barrier Glacier was described by Capps (1935) in his
report on the southern Alaska Range and was considered in
several reports on the hydroelectric potential of
Chakachamna Lake (Johnson, 1950~ Jackson, 1961; Bureau
Reclamation, 1962). Giles (1967) conducted a detailed
of
investigation of the terminal zone of Barrier Glacier.
Most recently, the u.s.G.S. investigated Barrier Glacier
as a part of a volcanic hazards assessment program at Mt.
Spurr (Miller, personal communication, 1981).
Giles' (1967) investigation of Barrier Glacier was the
most comprehensive to date and was specifically designed
-
to assess the possible impact of the glacier on hydro-W
electric development of Chakachamna Lake, and vice
versa. That work, which took place between 1961 and
1966, included mapping of the lake outlet area and
measurements of horizontal and vertical movement and of
ablation on various portions of the glacier. Those
measurements indicated that:
5-18
-
-
-
. .,..
'-'
(1) horizontal movement is in the range of 316 to 125
ft/yr on the debris-free ice and 28 to 1 ft/yr on
the debris-covered lobe of ice that forms the
southernmost component of the glacier's piedmont
lobe complex; and
(2) surface elevation changes were generally small (+0.8
to -2.9 ft/yr), but ablation on the relatively
debris-free ice averaged about 35 ft/yr in the
terminal zone.
Giles {1967) identified five ice lobes, two on the
debris-covered ice and three on the exposed ice, in the
terminal zone of Barrier Glacier. Examination of color
infrared aerial photographs for the current study
suggests th.at he defined topographie, but not necessarily
glaciologically-functional lobes or ice streams. For
example, on the debris-covered portion of the piedmont
zone, Giles identified two lobes on the basis of a deep
drainage that cuts across that zone. On the air photos
it is clear that the drainage in question parallels and
then trends oblique to the curvilinear flow features
preserved in the debris mantle. The drainage does not
appear to mark the boundary between two ice streams.
Giles (1967) concluded that the level of Chakachamna Lake
is controlled by Barrier Glacier, specifically by one
900-ft wide portion of debris-covered ice along the
river; that zone reportedly advances southward, into the
river channel, at a rate of about 25 ft/yr. Although the
rate of ice movement was apparently relatively constant
throughout the year, the low stream discharge in the
winter allows the glacier to encroach on the channel but
the ice is eroded back during the summer. Thus, Giles
5-19
suggested that there is metastable equilibrium in the
annual cycle. The annual cycle appears to be super-
imposed on a longer-term change such as that suggested by
Giles• measurements.
Observations made during analysis of the color infrared
(CIR) aerial photographs and during the 1981 field recon-
naissance lead to general agreement with the conclusions
produced by previous investigations. Nonetheless, the
CIR air photos and extensive aerial and ground-based
observations have allowed for the development of severa!
apparently new concepts regarding Barrier Glacier; those
new ideas may be summarized as follows:
(1) All of the moraines associated with Barrier Glacier
are the products of late Neoglacial advances of the
glacier and subsequent retreat. The large, sharp-
crested moraines that bound the glacier complex on
the eastern and a portion of the western margin
(Figure 5-2A) mark the location of the ice limit as
recently as a few hundred years ago (maximum
estimate) and perhaps as recently as the early to
middle part of this century. Cottonwood trees,
which are the largest and among the oldest of the
trees on the distal side of the moraine are
approximately 300 to 350 years old based on tree
ring counts on cores collected during the 1981 field
work (location of trees on Figure 5-2A). Those
dates provide an upper limit age estimate. The
vegetation-free character of the proximal side of
the moraine and the extremely sharp crest suggest on
even more youthful ice stand.
5-20
!RI
-
-
-
r'l!(,.g,
-
-
(2) When Barrier Glacier stood at the outermost moraine
(no. 1 above), the terminal piedmont lobe was larger
than that now present and probably included a
portion that floated on the lake; the present river
channel south of the glacier could not have existed
in anything near its present form at that time. The
extent of the piedmont lobe, as sugqested here, is
based on interpretation of the flow features
preserved on the debris-mantled portion of the
terminal lobe and the projected continuation of the
outermost moraine (no. 1 above}.
(3) The most recent advance of Barrier Glacier did not
reach the outermost moraine. It appears that the
flow of ice was deflected westward by pre-existing
ice and ice-covered moraine at the point where the
glacier begins to form a piedmont lobe. This pulse
was responsible for the vegetation-free zone of till
that mantles the ice adjacent to the debris-free ice
and for the large moraines that stand above the
delta at the northeast corner of the lake.
(4) The presently active portion of Barrier Glacier has
the same basic flow pattern as that described in no.
3, above, but the terminus appears to be retreat-
ing. The flow of ice is deflected westward as it
exits the canyon through which the glacier descends
the slopes of Mt. Spurr. The flow pattern is
clearly visible on and in the debris-free ice and is
further demonstrated by the distribution of the
distinct belt of volcanic debris present along the
eastern margin of the glacier.
5-21
(5) All of the above may be combined to suggest that the
large debris-mantled (ice-cored) lobe that forms the
most distal portion of the glacier complex, and
which borders the river, is now, at least in large
part, decoupled from the active portion of the
glacier. This interpretation in turn suggests that
the movements measured by Giles (1967) are due to
adjustments within the largely independent debris-
mantled lobe and to secondary effects transmitted to
and through this lobe by the active ice upslope.
(6) In spite of the fact that disintegration of the
debris-mantled lobe is extremely active locally, the
lobe appears to be generally stable because remanant
flow features are still preserved on its surface.
The debris cover shifts through time, thickening and
thinning at any given location as topographie
inversion takes place due to melting of the ice and
slumping and water reworking of the sediment. It
appears that the rate of mel~ing varies as a
function of the thickness of the debris cover, with
a thick cover insulating the ice and a thin cover
producing accelerated melting. Removal of the
covering sediment along the edge of the river leads
to slumping and exposure of ice to melt-producing
conditions. Thus the distal portion of the debris-
mantled lobe that borders the river is one site of
accelerated melting. Other areas of accelerated
melting are concentrated along drainages that have
developed within the chaotic ice-disintegration
topography.
5-22
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-
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'-
-
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i...,
-
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------~~"-----~------'
(7) There is no ice now exposed along the lake shore or
around the lake outlet, at the head of the
Chakachatna River, as was the case as recently as a
few decades ago (Giles, 1969) ~ These areas are
rather uniformly vegetated and the debris mantle
over the ice appears to be relatively thick compared
to areas where accelerated melting is taking place.
These areas appear to be reasonable models of what
to expect when melting of the ice and the associated
sorting and readjustment of the overlying debris
have produced a debris cover thick enough to
insulate the ice.
(8) If the debris-mantled ice lobe is functionally
decoupled from the active ice, as suggested above,
the move of ice toward the river is likely to
gradually slow in the near future. The Giles'
(1967) data suggest that this slowing may be
underway: the 1971 flood on the Chakachatna suggests
that the ice movement is still occasionally rapid
enough to constrict the river channel, however.
Nonetheless, it appears likely that, barring a
dramatic or catastrophic event, the degrading
portion of the ice lobe along the river will slowly
stabilize to a condition similar to that along the
lake shore. This will probably lead to a channel
configuration somewhat wider than at present but the
channel floor elevation is unlikely to change
significantly. This scenario assumes that the
discharge will remain relatively similar to that
today. If discharge increases, than a channel
deepening, as suggested by Giles (1967), may occur.
If discharge decreases, the available data suggest
that the outlet channel is likely to become more
5-23
5.2.1.4
narrow and perhaps more shallow as the debris-covered ice
continues to stabilize.
(9) Over the long term the possible changes along the
uppermost reaches of the Chakachatna River, where
the lake level is controlled, are potentially more
varied and more difficult to predict. One reason
for this is that the longer time frame (i.e.,
centuries vs. decades) provides an increased
probability for both dramatic (e.g., marked warming
or cooling of the climate) and catastrophic (e.g.,
large volcanic eruption) events. In this regard, it
should be noted that Barrier Glacier and the lake
outlet appear to be within the zone of greatest
potential impact from eruptions of Mt. Spurr volcano
(see Section 5.2.2).
Post and Mayo (1971) listed Chakachamna Lake as one of
Alaska's glacier-dammed lakes that can produce outburst
floods. They rated the flood hazard from the lake as
"very low" unless the glacier advances strongly. The
1971 flood on the Chakachatna (Lamke, 1972) was
attributed to lateral erosion of the glacier terminus at
the lake outlet. This flood may have, in fact, been
triggered by waters from an outburst flood at Pothole
Glacier, a surging glacier (Post, 1969) in the
Nagishlamina River Valley (Section 5.2.1.5).
Blockade Glacier
Blockade Glacier (Figure 5-l) originates in a very large
snow and ice field (essentially a mountain ice cap) , high
in the Chigmit Mountains south of Chakachamna Lake. This
same ice cap area is also the source of severa! of the
5-24
~
-
,,
:.î
-
-
-
-
-
-
-
-
-
--------------~---------~~-·
glaciers that flow to the south shore of Chakachamna Lake
(e.g., Shamrock, Dana, and Sugiura Glaciers; Figure
5-l) • Blockade Glacier flows southward out of the high
mountains into a long linear valley, which trends NE&SW
and which is apparently faul t con trolled (Section 5 .. 3) •
Once in the linear valley, Blockade Glacier flows both to
the northeast and to the southwest. The southwestern
brach terminates in Blockade Lake, which is one of
Alaska's glacier-dammed lakes that is a source of
outburst floods (Post and Mayo, 1971). The northeastern
branch of the glacier terminates near the mouth of the
McArthur River ~anyon and melt water from the glaciE~r
drains to the McArthur River.
Blockade Glacier is of specifie interest to the
Chakachamna feasibility study because one of its branches
does terminate so near the mouth of the McArthur River
Canyon, and a likely site for the powerhouse for the
hydroelectric project is in the lower portions of the
canyon (Section 3.0). Changing conditions at the
northeastern terminus of Blockade Glacier could
conceivably change the drainage of the McArthur River to
a degree that may influence conditions in the canyon,
i.e., at the proposed powerhouse sites in the canyon.
Blockade Glacier has not been the subject of previous
detailed studies such as those for Barrier Glacier
(Section 5.2.1.3). Observations made during the 1981
field reconnaissance covered the lower-elevation portions
of the source area and both terminal zones, but were
concentrated around the northeastern terminus, near the
McArthur River.
5-25
At its northeastern terminus Blockade Glacier is over two
miles wide. Over about half of that width (the northern
half) the glacier terminates in a complex of melt water
lakes and ponds that are dammed between the ice and Nec-
glacial moraines. The melt water from the lake system
drains to the McArthur River via one large and one small
rive/ that join and then flow into the McArthur about 2.5
miles downstream from the mouth of the McArthur River
Canyon. A complex of recently abandoned melt water
channels formerly carried flow to the McArthur at the
canyon mouth. A small advance of the ice front would
reinstitute drainage in these now dry channels.
Melt water issuing from the southern half of the ice
front flows to the McArthur River in braided streams that
cross a broad outwash plain. Whereas the northern
portion of the terminus is very linear, the southern
portion includes a distinct lobe of ice that is more than
a half mile wide and protrudes beyond the general ice
front by more than three-quarters of a mile. Another
notable characteristic of this zone is that the Nec-
glacial moraines, which are so prominent to the north,
have been completely eroded away by melt water along the
southern margin of the glacier.
On the basis of the above observations and the report
that Blockade Lake produces outburst floods (Post and
Mayo, 1971), it appears that the distinct features in the
southern portion of the northeast terminal zone are
present because this is the area where the outburst
floods exit the glacier front. The broad outwash plain
and the removal of the Neoglacial moraines are probably
both due to the floods; the vegetation-free (i.e.,
active) outwash plain is much larger than the size of the
5-26
•
-
~.
....
-
-
-
-
.....
-
"-
....
-
-
-
----~---------·-----~--~~·----~--l21m-,
melt water streams would suggest. The distinct lobe of
ice that protrudes beyond the general front of the
glacier probably marks the location of the sub-ice
channel through which the outburst floods escape.
The outermost Neoglacial moraines present near the
northeastern terminus lie about three-guarters of a mile
beyond the ice front. With the exception of the distinct
ice lobe, the general form of the ice front is mirrored
in the shape of the Neoglacial terminal moraines. The
outermost end moraine, which stands in the range of 20 to
40 ft above the surrounding outwash plain (distal) and
ground moraine {proximal) , is in the form of a continuous
low ridge with a gently rounded crest. Three or four
less distinct and less continuous recessional moraines
are present between the ice and the Neoglacial maximum
moraines. Distinct glacial fluting is present in the
till in this area.
The Neoglacial end moraine can be traced to a distinct,
sharp-crested Neoglacial lateral moraine that is
essentially continuously present along the glacier
mar~ins well up into the source area for Blockade
Glacier. The proximal side of the lateral moraine is
steep and vegetation-free, suggesting ice recession in
the very recent past. The crest of the lateral moraine
stands about 40 or 50 ft (estimate based on observations
from the helicopter) above the ice along the lower
portions of the glacier.
A readvance of Blockade Glacier's northeastern terminus
on the order of one-quarter to one-half a mile would
reestablish drainage through the abandoned channels near
the mouth of the McArthur River Canyon. Such a change is
5-27
unlikely to significantly impact conditions within the
canyon but would disrupt facilities (e.g., roads) on the
south side of the McArthur River, immediately outside the
mouth of the canyon. The glacier will have to advance
about three-quarters of a mile before conditions in the
canyon are likely to be seriously affected. An advance
of a mile and a half would essentially dam the mouth of
the canyon and would flood a major portion of the lower
reaches of the canyon, including the sites under con-
sideration for the powerhouse. Such a glacier-dammed
lake would likely produce outburst floods.
There is no evidence that any of the Neoglacial advances
of Blockade Glacier were extensive enough to dam the
McArthur River Canyon. The outmost of the Noeglacial !Mt
moraines lies at least one-quarter of a mile short of the
point where ice-damming of the canyon would begin, how-
ever. Outwash fans on the distal side of the mornine may
have produced minor ponding in the lowermost reaches
observed in the field and on the color infrared air
photos suggest that the last time that Blockade Glacier
may have dammed the McArthur Canyon was in late Naptowne
time, approximately 10,000 years or more ago.
The only reasonable mechanism th~t could produce an
advance of Blockade Glacier that would be rapid enough to
impact on the proposed hydroele::tric project is a glacier
surge; a surging glacier could easily advance a mile or
more within a period of a few decades. Evidence for
surges in the recent past might include an advancing
glacier front in an area where glaciers are generally in
recession and/or distorted medial moraines or long-
itudinal dirt bands on the glacier surface (Post, 1969;
Post and Mayo, 1971). It is clear that Blockade
5-28
-
ui
~
-
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,_
-
-
-
"'-
-
.,.._
>....
-
-
-
Glacier's recent history has been one of recession as is
the case for all other glaciers examined during the 1981
field reconnaissance. There are many distinct longitudi-
nal dirt bands and small medial ~oraines visible on the
surface of Blockade Glacier. If one or more of the indi-
vidual ice streams that comprise Blockade Glacier had
recently surged, such activity should be reflected in
contortions in the dirt bands and medial moraines.
Visible deformation of the surface features on the
glacier is very subtle and not suggestive of recent
surging of even individual ice streams in the glacier.
Thus, there is no evidence of a general surge of Blockade
Glacier in the recent past.
In summary, it appears that Blockade Glacier began to
withdraw from its Neoglacial maximum within the last few
hundred years. At that maximum stand, melt water drain-
age joined the McArthur River at the canyon mouth and
outwash may have produced sorne ponding and sediment
aggradation in the lower reaches of he canyon, but the
glacier was not extensive enough to have dammed the
canyon. Surging is the most reasonable mechanism that
could produce a future advance large enough and rapid
enough to impact on the proposed powerhouse sites in the
McArthur Canyon. No evidence suggestive of surging of
Blockade Glacier was identified during this study.
Currently, melt water is carried away from the canyon
mouth. Even markedly accelerated melt water production
from Blockade Glacier is unlikely to change this
condition or to have a negative impact on the proposed
hydroelectric project.
5-29
5.2.1.5 Other Glaciers
In order to get a reasonably broad-based sense of the
glacial record and history of recent glacier behavior in
the Cakachamna Lake region, the field reconnaissance
included aerial and ground-based observations of a nurnber
of the glaciers in the region in addition to Barrier and
Blockade Glaciers. Those glaciers included:
(1) Sharnrock Glacier, Dana Glacier, Sugiura Glacier, and
Firat Point Glacier along the south shore of
Chakachamna Lake (see figure 5-l for locations):
(2) Harpoon Glacier and Pothole Glacier in the
Nagishlamina River Valley:
(3) Alice Glacier, Crater Peak Glacier, and Brogan
Glacier on the slopes of Mt. Spurr, above the
Chakachatna River:
(4) Capps Glacier and Triumvirate Glacier on the eastern
slopes of Mt. Spurr; and
(5) McArthur Glacier in the McArthur River valley.
Post (1969) surveyed glaciers throughout western North
America in an effort to identify surging glaciers. Four
of his total of 204 surging glaciers for all of western
North America are in The Chakachamna study area (Figure
5-l). Three, including Pothole Glacier and Harpoon
Glacier, are located in the Nagishlamina River Valley,
tributary to Chakacharnna Lake, and one, Capps Glacier, is
on the eastern slope of Mt. Spurr. Surface features
5-30
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-
-
-
iolil
-
""""
,.,.;
-
-
-
'-
-
-
-
.....
-
indicative of surging are clearly visible on the co,lor
infrared aerial photographs used in this feasibility
study and were observed during field reconnaissance.
Specifie observations pertinent to an understanding of
the glacial history of the area and the feasibility study
include:
( 1) All of the glaciers listed above appear to have only
recently withdrawn from prominent Neoglacial
moraines, which in most (if not all) cases mark the
Neoglacial maximum advance positions of the
glaciers. These moraines and younger recessional
deposits are generally ice-cored for those glaciers
in groups 1 through 3 (above), but have little or no
ice core in groups 4 and 5, which terminate at
slightly lower elevations.
(2) Ponding and sudden draining of the impoundment
upstream of the Pothole Glacier (a surging glacier)
end moraine complex in the Nagishlamina River valley
may be an episodic phenomena that can produce
flooding in the lower portions of that valley and
thus a pronounced influx of water into Chakachamna
Lake. Published topographie maps (compiled in 1962)
show a small lake upstream of the end moraine, which
with the exception of a narrow channel along the
western valley wall, completely blocks the
Nagishlamina River Valley. That lake is no longer
present but there is clear evidence for its presence
and the presence of an even larger lake in the
recent past. Features on the floor of the lower
Nagishlamina River Valley suggest recent passage of
a large flood. Such a sudden influx of water into
5-31
Chakachamna Lake could produce significant changes at the
outlet from the lake. It may be that the 1971 flood on
the Chakachatna River (U.S.G.S., 1972) was triggered by
such an event, the stage having been set by the slow
increase in the level of Chakachamna Lake in the years
prior to the flood (Giles, 1967).
(3) Only glaciers south and east, and in the immediate
vicinity at Crater Peak on Mt. Spurr retain any
evidence of a significant cover of volcanic ejecta
from the 1953 eruption of Crater Peak. On both
Crater Peak Glacier and Brogan Glacier (see Figure
5-l) the ice in the terminal zone is buried by a
thick cover of coarse ejecta. The volcanic mantle,
--
where present, appears to be generally thick enough -
to insulate the underlying ice. The ejecta cover on
Alice Glacier is surprisingly limited. Areas where
the volcanic cover formerly existed, but was thin
enough so that its presence accelerated melting,
have probably largely been swept clean by the melt-
water. In any case, the only areas where there is
now evidence that the dark volcanic mantle has or is ~
producing more rapid melting is on the margins of
the thickly covered zones on the two cited glaciers.
(4) Highly contorted medial moraines on Capps Glacier,
Pothole Glacier, and Harpoon Glacier suggest that
several of the individual ice streams that comprise
those glaciers have surged in the recent past. No
comparable features were observed on any of the
other glaciers in the Chakachamna study area.
5-32
-
'il!lil)
5.2.1.6 -
-
-
-
-
"'""""
~1;>'
_.,.
-
-
Implications with Respect to the Proposed Hydroelectric
Project
Implications derived from the assessment of the glaciers
in the Chakachamna Lake area, with respect to specifie
project development alternatives, are included in Section
7.2. General implications, not directly tied to any
specifie design alternative, may be summarized as follows:
(1) In the absence of the proposed hydroelectric
project, the terminus of Barrier Glacier is likely
to continue to exist in a state of dynamic equilib-
rium with the Chakachatna River and to produce
small-scale changes in lake level through time; the
terminal fluctuations are likely to slow and
decrease in size in the future, leading to a more
stable condition at the lake outlet.
(2) If development of the hydroelectric project or
natural phenomena dam the Chakachatna River Valley
and flood the terminus of Barrier Glacier, the rate
of disintegration is likely to increase. If the
leve"l of the lake is raised, the rate of calving on
Shamrock Glacier is likely to increase.
(3) If hydroelectric development lowers the lake leve!,
the debris-covered ice of Barrier Glacier is likely
to encroach on and decrease the size of the river
channel; a subsequent rise in lake level could yield
conditions conducive to an outburst flood from the
lake. A lowering of the level of Chakahamna Lake
will also cause the short rivers that carry water
from Kenibuna Lake and Shamrock Lake into
5-33
5.f.2
5.2.2.1
Chakachamna Lake to incise their channels, thereby
lowering the levels of those upstream lakes over
time.
(4) There is no evidence to suggest that Blockade
Gl.acier will have an adverse impact on the proposed
hydroelectric project or that the project will have
any effect on Blockade Glacier.
(5) Glacier damming of the Nagishlamina River Valley may
result in outburst floods that influence conditions
at the outlet from Chakachamna Lake.
(6) With the exception of Shamrock Glacier, the terminus
of which may be affected by the lake level, there is
no evidence to suggest that the proposed project
will influence the glaciers (other than Barrier
Glacier) in the Chakachatna-Chakachamna Velley.
Changes in the mass balance of the glaciers will
influence the hydrolog~c balance of the lake-river
system, however.
Mt. Spurr Volcano
Alaska Peninsula-Aleutian Isl~nd Volcanic Arc
Mt. Spurr is an active volcano that rises to an elevation
above 11,000 ft at the eastern end of Chakachamna Lake.
Mt. Spurr is generally reported to be the northernmost of
a chain of at least 80 volcanoes that extends for a
distance of about 1,500 miles through the Aleutian
Islands and along the Alaska Peninsula; Iecent work has
identified another volcano about 20 miles north of Mt.
Spurr (Miller, persona! com~unication, 1981). Like Mt.
5-34
~
-
--
,_
-
~y
._
-
-
..,.,
-
-
-
'-
Spurr, about half of the known volcanoes in the
Aleutian Islands-Alaska Peninsula group have been
historically active.
The volcanoes of this group are aligned in a long arc
that follows a zone of structural uplift (Hunt, 1967) ,
and that lies immediately north of the subduction zone
the northern edge of the Pacifie Plate. The volcanoes on
the Alaska Peninsula developed on a basement complex of
Tertiary and pre-Tertiary igneous, sedimentary, and
metasedimentary rocks the pre-volcanic rocks are poorly
exposed in the Aleutian Islands. At the northern end of
the chain, such as at Mt. Spurr, the volcanoes developed
on top of a pre-existing topographie high. Mt. Spurr is
the highest of the volcanoes in the group and the summit
elevations generally decrease to the south and west.
The Alaska Peninsula-Aleutian Islands volcanic chain is,
in many ways, similar to the group of volcanoes in the
Cascade mountains of northern California, Oregon,
Washington, and southern British Columbia. In general,
both groups of volcanoes developed in already mountainous
areas, both consist of volcanoes that developed during
the Quaternary and include historically active volcanoes.
In both areas the volcanic rocks encompass a range of
compositions but are dominantly andesitic, and both
groups contain a variety of volcanic forms. The Alaskan
volcanoes include low, bread shield volcanoes, steep
volcanic cones, calderas, and volcanic dornes. Much of
the present volcanic morphology developed in late-and
post-glacial time.
5-35
5.2.2.2 Mt. Spurr
Capps (1935, p. 69-70} reported, "The mass of which the
highest peak is called Mt. Spurr consists of a great
outer crater, now breached by the alleys of several
glaciers that flow radially from it, and a central core
within the older crater, the highest peak of the
mountain, from vents near the top of which steam sorne-
times still issues. One small subsidiary crater, now
occupied by a small glacier, was recognized on the south
rim of the old, outer crater."
Subsequent work has shawn that Capps' obsArvations were,
in pa.rt, in err or. The err or is speci f ically related to
the suggestion that the peaks and ridges that surround
the summit of Mt. Spurr mark the rim of a large, old
volcanic crater. Why Capps had this impression is clear
because as one approaches the mountain from the east or
southeast, the view strongly suggests a very large
crater~ such a view has suggested to many geologists that
Capps was correct in his observations. It is only when
one gets up on the mountain, an opportunity made
practical by the helicopter, that it becomes clear that
most of the "crater rim" consists of granitic and not
volcanic rocks. The most recent and comprehensive report
on the distribution of lithologies present on Mt. Spurr
is found in Magoon and others (1976). The u.s.
Geological Survey plans to issue an open file report on
Mte Spurr in 1982 (Miller, persona! communication, 1981). ~·
Field work aimed at assessing the potential impact of ~
volcanic activity from Mt. Spurr on the proposed hydro-
electric development at Chakachamna Lake was concentrated
in the area bounded by the Nagishlamina River on the
5-36
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~
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~-
-
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-
""""
-
""""
-
'-'
------------
west, the Chakachatna River on the south, a north-south
line east of the mountain front on the east, and the
Harpoon Glacier-Capps Glacier alignment on the north
(Figure 5-l) • Most of the observations at the higher
elevations were from the helicopter~ landing locations
high on Mt. Spurr are few and far between and many of the
steep slopes are inaccessible to other than airborne
observations. It was possible to make numerous surface
observations in the Nagishlamina River and Chakachatna
River valleys and on the slopes below 3,000 ft elevation
to the south and southeast of the summit of Mt. Spurr.
Observations made during the 1981 reconnaissance indicate
that the Quaternary volcanics of Mt. Spurr, with the
exception of airfall deposits, are largely confined to a
bread wedge-shaped area bounded generally by Barrier
Glacier, Brogan Glacier, and the Chakachatna River
(Figures 5-l and 5-2); the distribution of Quaternary
volcanics north of the summit, in areas that do not drain
to the Chakachamna-Chakachatna basin, was not
investigated.
The bedrock along the western margin of Barrier Glacier
is dominantly granite. The only exception observed
during the field reconnaissance, which focused at
elevations below about 5,000 ft, was an area where the
granite is capped by lava flows (Figure 5-2). East of
Barrier Glacier the slopes above about 2,000 ft consist
of interstratified lava flows and proclastics, which are
exposed in cross section. The slopes of Mt. Spurr in
this area are not the product of triginal volcanic
deposition but are erosional features. Thus, it is clear
that the volcanics once extended farther to the south and
southwest into what is now the Chakachamna Lake basin and
5-37
Chakachatna River Valley. The lower slopes immediately
east of Barrier Glacier and south of Mt. Spurr consist of
a broad alluvial fan complex.
Between Alice Glacier and the mountain front, the upper
slopes of Mt. Spurr, where not buried by glacier ice or
Neoglacial deposits, expose interbedded lava flows (often
with columnar jointing), pyroclastic units, and volcanic-
lastic sediments. As is the case near Barrier Glacier,
most of the slopes in this area are steep, often near
vertical erosional features that expose the volcanic
sequence in cross-section. The primary exception to this
is found on and adjacent to Crater Peak where sorne of the
slopes are original depositional features.
Crater Peak was the site of the most recent eruption of
Mt. Spurr. That eruption, which took place in July,
1953, was described by Juhle and Coulter (1955). The
1953 eruption produced an ash cloud that was observed as
far east as Valdez, lOO miles from the volcano, the
distribution of ejecta on Mt. Spurr demonstrates that
virtually all of the airborne material traveled eastward
with the prevailing winds. The thick debris cover on
Crater Peak and Brogan Glaciers (Figure 5-2) is largely
the product of this eruption.
Any lava that issued from Crater Peak in 1953 was limited
to the slopes of the steep-sided cone. The eruption did
produce a debris flow, which began at.the south side of
the crater where volcanic debris mixed with water from
the glacier that reportedly occupied the crater (Capps,
1935) and the outer slopes of the cone began to move
downslope toward the Chakachatna River. The debris flow,
which was probably more a flood than a debris flow
5-38
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initially, eroded a deep canyon along the eastern margin
of Alice Glacier, through the Neoglacial moraine complex
at the terminus of Alice Glacier, and through older
volcanics and alluvium adjacent to the Chakachatna
River. When it reached the Chakachatna River, the debris
flow dammed the river and produced a small lake that
extended upstream to the vicinity of Barrier Glacier.
The dam was subsequently partially breached, lowering the
impoundment in the Chakachatna Valley to its present.
level. Evidence for the high water level includes
tributary fan-deltas graded to a level above the current
water level and a "bath tub ring" of sediment and little
or no vegetation along the southern valley wall.
East of the 1953 debris flow, the Chakachatna River flows
through a narrow canyon within the broader valley bounded
by the upper slopes of Mt. Spurr on the north and the
granitic Chigmit Mountains on the south. The southern
wall of the canyon (and valley, as whole) consists of
glacially-scoured granitic bedrock. With the exception
of remnant deposits of the 1953 debris flow that are
present against the granitic bedrock (Figure 5-2), the
1981 reconnaissance yielded no evidence of volcanic or
volcaniclastic rocks on the southern wall of the
Chakachatna Valley. The northern wall of the
Chakachatna Canyon exposes a complex of highly weathered
(altered ?) andesitic lava flows, pyroclastics,
volcaniclastic sediments, outwash, and in one location,
what appears to be an old (pre-Naptowne) till.
5-39
Although the general late-Quaternary history of the
Chakachatna River Valley is reasonably clear, the details
of that history are very complex and would reguire an
extensive field program to unravel. The observations
made during the 1981 reconnaissance suggest the following:
(1) Late-Tertiary and/or early-Quaternary volcanic
activity at Mt. Spurr built a thick pile of lava
flows, proclastics, and volcaniclastic sediments on
top of a granitic mountain mass of sorne considerable
relief.
(2) Interspersed volcanic and glacial activity occurred
during the Pleistocene, with alternating periods of
erosion and deposition. The width of the valley at
Chakachamna Lake is maintained downstream to the
area of Alice Glacier (Figure 5-2) • From that point
to the mountain front, where the same broad valley
form seems to reappear, the overall valley is
plugged by a complex. of volcanic (and glacial)
deposits. This, along with the volcanic cliffs high
on the slopes of Mt. Spurr, suggests that volcanics
once largely filled what is now the Chakachatna
Valley, that glaciers then eroded a broad, U-shaped
valley (such as is stjll present in the lake basin),
and that subsequent volcanic activity produced the
bulk of the deposits that form the valley "plug".
(3) The age of the volcanics in the "plug" is not
clear. Sorne of the characteristics of the basal
volcanic rocks exposed along the river suggest sorne
antiquity. For example, many lava flows are so
deeply weathered (or altered ?) that the rocks
disintegrate in one's hand. These ~olcanics appear
5-40
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ta be overlain by outwash and may be interbedded
with till, which is also deeply weathered
(altered?) • These and other features suggest that
at least sorne of the volcanics in this area were
deposited in pre-Naptowne time. Glacial deposits,
including moraines, a large area of kame and kettle
deposits,and glacier-marginal lake deposits
interpreted ta be a late-Naptowne age overlie
portions of the volcanic valley plug. [See Section
7.2 for discussion of implications with respect ta a
dam in the Chakachatna Canyon.]
In contrast, it is difficult ta understand how the
apparently easily eroded volcanics in this area
survived the Naptowne-age glaciers that filled the
Chakachatna Valley and were large enough ta extend
across Cook Inlet (Karlstrom, 1964). In addition,
there are many landforms, such as volcanic
pinnacles, that clearly are post glacial as they
could not have survived being overriden by glacier
ice. Such landforms demand the removal of several
tens of feet of volcanics over large areas.
Although the evidence is conflicting and an unambig-
uous interpretation difficult, it does appear that
much of the volcanic valley plug is of pre-Naptowne
age. The basis for this conclusion is most clearly
documented by the presence of outwash on top of
volcanics, a sequence exposed at several sites in
the canyon. The outwash is capped by a three-to-four
foot thick cap of volcanic ash (many discrete
depositional units) as is typical of Naptowne-age
surfaces in the area. Just how these volcanics
survived the Naptowne glaciation is not clear •
5-41
(4) Following the withdrawal of the Naptowne ice from
the Chakachatna River Valley, Holocene volcanic
activity, glacial activity, and fluvial and slope
processes have produced the present landscape.
Most, if not all of the present inner canyon,
through which the Chakachatna River flows, appears
to be the product of Holocene downcutting by the
river.
Given that many of the details of the Quaternary history
of Mt. Spurr are not well understood, it is nonetheless
clear that Mt. Spurr is an active volcano that may
produce lava flows, pyroclastics, and volcaniclastic
sediments in the immediate vicinity within the life of
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-
the project. Airfall deposits ~an be expected to ~
influence a larger area. Considering the size and type
of volcanic events for which there is evidence at Mt.
Spurr and the present topography, the area of interest to
the proposed hydroelectric project most likely to be
affected is the area between Barrier Glacier and the 1953
debris flow. The topography of the valley plug volcanics
appears to afford sorne, but certainly not total
protection to the canyon portion of the river valley; an
example of this "protection" is provided by a second
debris flow produced in 1953 that was prevented from
reaching the river by intervening topography on the
valley "plug".
The types of volcanic event judged to be most likely to
impact the Chakachatna River Valley in the near future
are:
(1) 1953-type debris flows which could inundate a
portion of the valley and re-dam the river,
5-42
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5.2.2.3
(2) lava flows, which could enter and dam the valley, and
( 3) large floods that would be produced by the melting
of glacier ice during an eruption.
Post and Mayo (1971) suggested that melting of glacier
ice on Mt. Spurr during volcanic activity may present a
serious hazard. Significant direct impact on Barrier
Glacier would demand a summit eruption that included the
flow of hot volcanics at least into the upper reaches of
the glacier on the development of a new eruptive center
(such as Crater Peak) west of the present summit. Of
course the character of the volcanoes in the Aleutian
Island-Alaska Peninsula chain make it clear that a very
large event (i.e., a Mt. St. Helens--or even a Crater
Lake-type event) is possible at Mt. Spurr; such an event
has a very low annual probabilty of occurrence at any
given site, however.
Implications with Respect to the Proposed Hydroelec~ric
Project
The potential impact of Mt. Spurr on the proposed
hydroelectric project will, in part, vary as a function
of the project design (see Section 7.2), but sorne
potential will always exist because of the location of
Mt. Spurr relative to Chakachamna Lake and the
Chakachatna River. The amount of negative impact on the
project is clearly a function of the size of volcanic
event considered; larger events, which would have the
greatest potential for adverse impact, are, in general,
less likely to occur than smaller volcanic events. Sorne
general possibilities that might be associated with low-
to medium-intensity events (such as a Crater Peak event
or slightly larger) include:
5-43
( 1) Damming of the Chakachatna Ri ver by lava or debris
flows, with the most likely site being in the
vicinity of the 1953 debris dam. Flooding of the
terminus of Barrier Glacier may increase the rate of
ice melt and possibly alter the configuration of the
current lake outlet. Any project facilities on the
valley floor of the upper valley would be buried by
the flow and/or flooded.
(2) Flooding of the Chakachatna River Valley as a result
of the melting of glacier ice on Mt. Spurr during an
eruption. Project facilities near or on the valley
floor would be flooded.
(3) Accelerating the retreat of Barrier Glacier due to
the flow of hot volcanic debris onto the glacier.
In the extreme, Barrier Glacier could be eliminated
if enough hot material flowed onto the ice. A less
dramatic scenario could include destabilization of
the lake outlet due to accelerated melting in the
terminal zone of Barrier Glacier. In contrast, a
large lava flow at the present site of Barrier
Glacier could replace the glacier as the eastern
~'
margin of the lake, providing a more stable dam than ~
that provided by Barrier Glacier.
Each of the design alternatives (Section 3.0) includes a
lake tap in the zone between the lake outlet and First
Point Glacier. Although it is generally true that a site
farther from Mt. Spurr is less likely to be subject to
volcanic hazards than a site closer to the volcano, there
is no apparent reason to favor one particular site in the
proposed zone over any other site in that zone. A large
eruptive event, apparently substantially larger than any
5-44
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5.2.3
5.2.3.1
of the Holocene events on Mt. Spurr, would be required
before the proposed lake tap site would be directly
threatened by an eruption of Mt. Spurr.
Slope Conditions
The Chigmit Mountains, south of Chakachamna Lake and the
Chakachatna River, and the Tordrillo Mountains, to the
north, contain many steep slopes and near-vertical
cliffs. This landscape is largely the product of
multiple glaciation during the Quaternary, including
Neoglaciation which continues in the area today. The
proposed hydroelectric project is likely to include
facilities in the Chakachamna Lake basin and either or
both of the McArthur and Chakachatna River valleys. Any
above-ground facilities in these areas will be on or
immediately adjacent to steep slopes, and thus subject to
any slope processes that may be active in the area.
Because of this fact, the 1981 field reconnaissance
included observations of slope conditions in the areas of
interest. Field work scheduled for 1982 will include
detailed assessment of bedrock characteristics, such as
joint orientations, that influence slope conditions.
Chakachamna Lake Area
Chakachamna Lake sits in a glacially overdeepened basin
that is generally bordered by steep slopes of granitic
bedrock that was scoured during Naptowne and earlier
glaciations. Locally, such as along the southern valley
wall west of Dana Glacier (Figure 5-2) , distinct bedrock
benches are present. In other areas, the slopes rise,
with only minor variation in slope, from the lake level
to the surrounding peaks. All principal valleys along
5-45
5.2.3.2
the southern side of the lake presently contain
glaciers. The principal valleys tributary to the north
side of the lake, the Chilligan and Nagishlamina, are
larger than those on the south side of the lake and are
currently essentially ice-free, although their present
form is clearly the product of glacial erosion.
No evidence of large-scale slope failures of the slopes
in the Chakachamna Lake basin was observed during the
1981 field reconnaissance. Most of the slopes are
glacially-scoured bedrock and are essentially free of
loose rock debris, although talus is locally present.
The orientation of joint sets in the granitic bedrock
varies somewhat from area to area. In many ar~as a near
horizontal out-of-slope joint set is present, but it
tends to be poorly expressed relative to more
steeply-dipping joints. Field work indicates that this
and cross-cutting joints have formed boulner-size pieces
and small slabs that produce rockfall as the only common
type of slope failure ~or which any evidence was found.
This condition is apparently most pronounced along the
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southern valley wall, between Sugiura Glacier and the ~
lake outlet.
Chakachatna River Valley
The Chakachatna River, from its origin at Chakachamna
Lake to the mountain front, flows through a valley that
is rather variable in its form and characteristics along
its length and from side to side. Throughout the valley,
the south side consists of steep glaciated granitic
bedrock slopes that rise essentially continuously from
the river to the adjacent mountain peaks. All major
tributary valleys on the southern valley wall, many of
5-46
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which are hanging alleys, now contain glac~ers. The
comments regarding slope conditions on the slopes above
the lake (Section 5.2.3.1) apply to the southern wall of
the Chakachatna River Valley •
The north side of the valley differs from the south side
in virtually every conceivable way. On this side bedrock
is volcanic, and glacial and fluvial sediments are also
present. In the westernmost portion of the valley, the
river is bordered by the Barrier Glacier moraine and
alluvial fans: steep volcanic slopes above the alluvial
fans are subject to rockfall activity. Between Alice
Glacier (the area of the 1953 debris flow) and the valley
mouth, the river flows through a narrow canyon, the north
side of which consists of a variety of interbedded
volcanics, glacial deposits, and fluvial sediments
(Figure 5-2) • The north canyon wall has been the site of
several landslides that range in size from small slumps
to large rotational slides. Such activity is likely to
continue in the future. Its impact will most frequently
be limited to the diverbion of the main river course away
from the north canyon wall~ there are several examples of
this now present in the canyon. A large landslide, which
appears to be unlikely given the height of the slopes,
could completely dam the canyon; partial damming with
temporary ponding appears to be a more likely possibility.
Volcanic activity on Mt. Spurr could directly influence
conditions along the Chakachatna River (Section 5.2.2},
or could, by slowly altering conditions along the north
wall of the canyon, have a secondary impact on the valley.
5-47
5.2.3.3 McArthur River Canyon
The McArthur River Canyon is a narrow·, steep-walled
glaciated valley. A possible powerhouse site has been
identified along the north wall of the canyon (Section
3.0) and the following cornrnents specifically refer to
the north wall of the McArthur River Canyon. The val-
ley walls, which consist of granitic bedrock, expose a
complex of cross-cutting joint sets and shear zones.
The character and dominant orientations of the joints
and shears vary along the length of the canyon and the
character of the slopes also varies, apparently in di-
rect response.
Except near the canyon mouth, there is no evidence of
large-scale slope failure and rockfall is the dominant
slope process. Between the terminus of McArthur Glacier
and Misty Valley (Figure 5-l) the joint sets are of a
character and orientation such that rockfall has been
active and the bedrock on the lower slopes on the north
valley wall are uniformly buried beneath a thick talus.
The vegetation on the talus suggests that the bulk of
talus development took place sorne time soon after de-
glaciation and rockfall has been less active recently.
The slopes between Misty and Gash Valleys (Figure 5-l)
consist of glacially-scoured bedrock that is essentially
talus free, suggesting little or no rockfall in this
area.
From Gash Valley to the canyon mouth, the granitic
bedrock appears to become progressively more intensely
jointed and sheared and thus more subject to rockfall and
small-scale slumping. Talus mantles the lower slopes in
much of this area. A large fault zone (Section 5.3) is
-48-
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5.2.3.4
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present at the canyon mouth. The fault has produced
intense shearing over a broad zone that is now subject to
intense erosion and is the site of several landslides .
Implications with Respect to the Proposed Hydroelectric
Project
As is the case for volcanic hazards, there is no apparent
reason with respect to slope conditions to favor one site
over any other in the zone between the lake outlet and
First Point Glacier for the lake tap. Rockfall appears
to be the only potential slope hazard in that zone; there
was no evidence observed in the field to suggest other
types of slope failure.
As indicated on Figure 5-9, the Castle Mountain fault
(Section 5.3), which is a major fault, crosses the
McArthur River just outside the canyon mouth where the
granitic bedrock has been badly shattered by fault
movement. Surface examination reveals that the rock
quality progressively improves with distance upstream
from the canyon mouth and the best quality rock lies
between Gash Valley and Misty Valley (Figure 5-l) ,
beginning about 1-1/2 miles upstream from the powerhouse
location presently shown on the drawings. This location
is based on economie considerations alone, without taking
account of the higher excavations costs that would be
associated with the poorer quality rock. A critical
evaluation of the rock conditions in this area will be
included in the 1982 studies and a site will be selected
for drilling a deep core hole.
5-49
5.3
5.3.1
A powerhouse site at or immediately outside the canyon
mouth, as has been considered in other studies, is likely
to be in the fault zone and subject to fault rupture as
well as high ground motions. In addition, facilities
outside the canyon will be in Tertiary sedimentary rocks
and glacial deposits, not granite.
Seismic Geology
Tectonic Setting
The active faulting, seismicity, and volcanism of
southern Alaska are products of the regional tectonic
setting. The primary cause of the faulting and seismic
activity is the stress imposed on the region by the
relative motion of the Pacifie lithospheric plate
relative to the North American plate along their common
boundary (Figure 5-3). The Pacifie plate is moving
northward relative to the North American plate at a rate
of about 2.4 inchesjyear (Woodward-Clyde Consultants,
1981 and references therein) • The relative motion
between the plates is expressed as three styles of
deformation. Along the Alaska Panhandle and eastern
margins of the Gulf of Alaska, the movement between
plates is expressed primarily by high-angle strike-slip
faults. Along the northern margins of the Gulf of
Alaska, including the Cook Inlet area, and the central
and western portions of the Aleutian Islands, the
relative motion between the plates is expressed by the
underthrusting of the Pacifie plate beneath the North
American plate. At the eastern end of the Aleutian
Islands, the relative plate motion is expressed by a
complex transition zone of oblique thrust faulting.
5-50
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The Chakachamna Lake area is located in the region where
the interplate motion is producing underthrusting of the
Pacifie plate beneath the North American plate. This
underthrusting results primarily in compressional
deformation, which causes folds, high-angle reverse
faults, and thrust faults to develop in the overlying
crust. The boundary between the plates where under-
thrusting occurs is a northwestward-dipping megathrust
fault or subduction zone. The Aleutian Trench, which
marks the surface expression of this subduction zone, is
located on the ocean floor approximately 270 miles south
of the Chakachamna Lake area. The orientiation of the
subduction zone, which may be subdivided into the mega-
thrust and Benioff zone (Woodward-Clyde Consultants,
1981) , is inferred at depth to be along a broad inclined
band of seismicity that dips northwest from the Aleutian
Trench.
The close relationship between the subduction zone and
the structures within the overlying crust introduce~
important implications regarding the effect of the
tectonic setting on the Ghakachamna Lake Project. The
subduction zone represents a source of major earthquakes
near the site. Faults in the overlying crust, which may
be subsidiary to the subduction zone at depth, are
sources of local earthquakes and they may present a
potential hazard for surface fault rupture. This is of
special concern because the Castle Mountain, Bruin Bay,
and several other smaller faults have been mapped near to
the Chakachamna Lake Hydroelectric Project area
(Detterman and ethers, 1976; Magoon and ethers, 1978) •
Future activity on these faults may have a more profound
affect on the seismic design of the project structures
than the underlying subduction zone because of their
closer proximity to proposed project site locations.
5-51
5.3.2
5.3.2.1
Historie Seismicity
Regional Seismicity
Southern Alaska is one of the most seismicially active
regions in the world. A number of great earthquakes
(Richter surface wave magnitude Ms 8 or greater) and
large earthquakes (greater than Mx 7) have been recorded
during historie time. These earthquakes have primarily
occurred along the interplate boundary between the
Pacifie and North American plates, from the Alaskan
panhandle to Prince William Sound and along the Kenai and
Alaska Peninsulas to the Aleutian Islands. Among the
recorded earthquakes are three great earthqcakes that
occurred in September 1899 near Yakutat Bay, with
estimated magnitudes Ms of 8.5, 8.4, and 8.1 (Thatcher
and Plafker, 1977}. Ground deformation was extensive and
vertical offsets ranged up to 47 ft. (Tarr and Martin,
1912); these are among the largest known disp1acements
attributable to eartpquakes. Large parts of the plate
boundary were reuptured by these three earthquakes and by
twelve others that occurred between 1897 and 1907; these
inc1uded a magnitude Ms 8.1 event on 1 October 1900
southwest of Kodiak Island (Tarr and Martin, 1912; McCann
and others, 1980) and a nearby magnitude Ms 8.3
earttquake on 2 June 1903, near 57° north latitude, 156°
west longitude (Richter, 1958).
A similar series of major earthquakes occurred along the
plate boundary between 1938 and 1964. Among these
'J ...
-
1
'~.ii
earth uakes were the 1958 Lituya Bay earthquake (Ms 7.7) ~
and the 1972 Sitka earthquake (Ms 7.6), bath of which
occurred along the Fairweather fault system in southeast
Alaska; and the 1964 Prince William Sound earthquake
5-52
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5.3.2.2
(Ms 8.5}, which ruptured the plate boundary over a wide
area from Cordova to southwest of Kodiak Island and which
produced up to 39 ft. of displacement (Hastie and Savage,
1970). Figure 5-4 shows the aftershock zones of these
and other major earthquakes in southern Alaska and the
Aleutian Islands. The main earthquakes and aftershocks
are inferred to have ruptured the plate boundary in the
encircled areas.
Three zones along the plate boundary which have not
ruptured in the last 80 years have been identified as
"seismic gaps" (Sykes, 1971). These zones are located
near Cape Yakataga, in the vicinity of the Shumagin
Island, and near the western tip of the Aleutian Chain as
shown in Figure 5-4. The Yakataga seismic gap is of
particular interest to the project because of its
proximity to the site region. The rupture zone of a
major earthquake filling this gap has the potential to
extend along the subduction zone to the north and
northwest of the coastal portion of the gap near Yakataga
Bay.
Historie Seismicity of the Project Study Area
The historie seismicity within 90 miles of the project
area, approximately centered on the east end of
Chakachamna Lake, is shown in Figures 5-5, 5-6, and 5-7.
The earthquake locations are based on the Hypocenter Data
File prepared by NOAA (National Oceanic and Atmospheric
Administration, 1981). The Hypocenter Data File includes
earthquake data from the u.s. Geological Survey and other
sources and represente a fairly uniform data set in terms
of quality and completeness since about 1964.
5-53
Based on Figures 5-5, 5-6, and 5-7 and data available in
the open literature, the seismicity of the project area
is primarily associated with four principal sources~ the
subduction zone, which is divided into two segments--the
Megathrust and Benioff zone (Woodward-Clyde Consultants,
1981,~ Lahr and Stephen, 1981) 1 the crustal or shallow
seismic zone within the North American Plate~ and
moderate to shallow depth seismicity associated with
volcanic activity. The seismic sources are briefly
discussed below in terms of their earthquake potential.
The Megathrust zone is a major source of seismic activity
that results primarily from the interplate stress
accumulation and release along a gently inclined boundary
between the Pacifie and North American plates. This zone
is the source area of many of the large to great earth-
quakes, include the Ms 8.5 1964 Prince William Sound
earthquake, which ruptured along the inclined plate
boundary from the eastern Gulf of Alaska to the vicinity
of Kodiak Island. The maximum magnitude for an
earthquake event along the Megathrust zone is estimated
to be Ms 8.5 (Woodward-Clyde Consultants, 1980, 1981).
The Benioff zone portion of the subduction zone is
believed to be restricted to the upper part of the
descending Pacifie plte, which lies beneath the North
American plate in southern Alaska. This zone is the
source of smaller magnitude and more continuous
earthquake activity relative to the Megathrust zone. No
earthquakes larger than about Ms 7.5 are known to occur
along the Benioff zone and therefore, a maximum magnitude
earthquake of Ms 7.5 is estimated for this zone
(Woodward-Clyde Consultants, 1981) •
5-54
.....
-
,_
-·
'"""'
-
""""
-
"-
"-
"'-
-
--------·----·-----
The primary source of earthquakes in the crustal or
shallow seismic zone is movement along faults or other
structures due to the adjustment of stresses in the
crust. As shown in Figure 5-7, the historie seismicity
of the crustal zone within a large part of the project
study area is low. The data base used to compile the
historie seismicity of the crustal zone for this study
has no recorded earthquakes in the vicinity of
Chakachamna Lake.
The majority of the recorded earthquakes shown in Figure
5-7 are located along the eastern and southern margins of
the project study area. Most of these events have not
been cor related or associat.ed wi th any known crustal
structures, with the possible exception of one event that
is associated with the Castle Mountain fault. As
discussed in Section 5.3.3.3, the Castle Mountain fault
is one of the two major faults present in the project
study area. It passes within a mile or less of the
proposed project facilities in the McArthur River
drainage and within 11 miles of the proposed facilities
at Chakachamna Lake. Evidence for displacment of
Holocene deposits has been reported in the Susitna
lowlands, in the vicinity of the Susitna River (Detterman
and others, 1976a). Although a number of recorded
earthquakes are located along the trend of the Castle
Mountain fault (Figure 5-7), only one event, an Ms 7
earthquake in 1933, has been associated with the fault
(Woodward-Clyde Consultants, 1980b) • A maximum magnitude
earthquake of Ms 7.5 has been estimated for the Castle
Mountain fault (Woodward-Clyde Consultants, 1981).
5-55
Further studies (planned for 1982) are needed to assess
the possible association of other historie earthquakes
shown in Figure 5-7 with candidate significant features
identified in the fault investigation phase of the
project study.
Because of the proximity of the project site to active
volcanoes of the Aleutian Islands-Alaska Peninsula
volcanic chain, including Mt. Spurr which is located
immediately northeast of the Chakachamna Lake, volcanic-
induced earthquakes are considered a potential seismic
source. Active volcanism can produce small-to-moderate
magnitude earthquakes at moderate-to-shallow depths due
to the movement of magma or local adjustments of the
earth's crust.
Occasionally, severe volcanic activity such as phreatic
explosions or explosive caldera collapses may be
accompanied by significant earthquake events. Because
such large volcanic events are rare, there is little data
from which to estimate earthquake magnitudes that may be
associated with them. However, because of the
similarities in characteristics of the Mount St. Helens
volcano to those of the Aleutian chain (including Mt.
Spurr), it is reasonable to assume that earthquakes
associated with the recent Mount St. Helens eruption of
May 1980 may also occur during future volcanic activity
of Mt. Spurr and others in the Aleutian chain. The
largest earthquake associated with the Mount St. Helens
explosive eruption that occurred on 18 May 1980 had a
magnitude of 5.0. Numerous smaller earthquakes with
magnitudes ranging from 3 to 4 were recorded during the
period preceding trhe violent rupture of Mount St. Helens
(U.S. Geological Survey, 1980).
5-56
loirliiiW
1illlli
-
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-
5.3.3
-5.3.3.1
·._
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-
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5.3.3.2
'-
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As part of a volcanic hazard monitoring program, the U.S.
Geological Survey has been operating several seismograph
stations in the vicinity of Mt. Spurr to assess its
activity. Data acquired by these stations are not
presently available but will be released in 1982 as an
Open-File Report (Lahr, J. C., personal communication,
1981).
Fault Investigation
Approach
The objectives of the Chakachamna Lake Hydroelectric
Project seismic geology task are:
(1) to identify and evaluate significant faults within
the project study area that may represent a
potential surface rupture hazard to project
facilities and
(2) to make a preliminary evaluation of the ground
motions (ground shaking) to which proposed project
facilities may be subjected during earthquakes. In
order to meet the specifie task objectives and to
provide a general assessment of the seismic hazards
in the project area, the seismic geology study was
designed and conducted in a series of sequential
phases (Figure 5-8) •
Work to Date
The study phases reported here include review of
available literature, analysis of remotely sensed data,
aerial field reconnaissance, and acquisition of law-sun-
angle aerial photographs.
5-57
Information of a geologie, geomorphic, and seismologie
nature available in the open literature was evaluated to
identify previously reported faults and lineaments that
may be fault related within the project study area.
Geologists presently working in the area or familiar with
the study area were also ·contacted. The locations of all
faults and lineaments derived from the literature review
and discussions with other geologists were plotted on
1:250,000-scale topographie maps.
Lineaments interpreted to be fault related were also
derived from the analysis of high-altitude color-infrared
{CIR) aerial photographs (scale 1:60,000) and Landsat
imagery (scale 1:250,000} of the study ar~a outlined by
the 30-mile diameter circle on Figure 5-9. These
lineaments were initially plotted (with brief annotation)
on clear mylar overlays attached to lhe photographs and
images on which they were observed. The lineaments were
then transferred and plotted on the 1:250,000-scale
topographie maps. The faults and lineaments identified .
from the review of the available literature and
interpretation of CIR photographs and landsat imagery
comprise a preliminai.y inventory of faults and lineaments
w
wi thin the study area. .r
Th~ faults and lineaments in the preliminary inventory
were then screened on the basis of a one-third length
length-distance criterion to select those faults and
lineaments within the study area that potentially could
produce surface rupture at sites proposed for
facilities. The length-distance criterion specifies a
minimum length for a fault or lineament and a minimum
' distance from the project site for a fault or lineament
to be retained for further study. For example, a fault
5-58
-
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-
-
-
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-
-
~
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'""""
'-
'-"
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or lineament that trends toward the project site and has
an observed length of 10 miles would be selected for
further study if it was less than 30 miles from the
project site. A fault or lineament with the same trend
and same length, but at a distance of greater than 30
miles from the project site would not be selected for
further study.
The one-third length-distance criterion used is based on
the empirical data that suggest that fault rupture rarely
occurs along the full length of a fault (except for very
short faults) during an earthquake (Slemmons, 1977,
1980). The length-distance criterion also takes into
account
(1) the possibility of surface rupture within or near to
the project site occurring on faults that may be
identified only in areas remote from the project
site, but which in actuality may extend undetected
to the project site, and
(2) the fact that at greater distances from the project
site, only enger faults would have the potential of
producing rupture at the site.
Regional faults in southern Alaska that are known or
inferred to be active but are distant from the project
study area were not evaluated for surface rupture
potential. These faults, because of their activity, were
considered to be potential seismic sources and therefore
were evaluated in terms of their potential for causing
significant ground motions at the project site.
5-59
The faults and lineaments selected for further study on
the basis of the length-distance criterion or because
they appeared to be potential sources of significant
ground shaking were transferred to 1:63,360-scale
topographie maps for use during the aerial reconnaissance
phase. During the aerial rer.onnaissance, the faults were
examined for evidence (geologie features, and geomorphic
expression) that would suggest whether or not youthful
activity has occurred. The lineaments were examined to
assess:
(1) whether they are or are not faults, and
(2) if they are not faults, what is their origin. For
those linearoents that were interpreted to be faults
or fault-related, further examination was made to
look for evidence that would be suggestive of
youthful activity.
After the aerial reconnaissance evaluation of the faults
and lineaments, each feature was classified into one of
three categories:
(1) a candidate significant feature;
(2) a non-significant feature; or
(3) an indeterminate feature.
Candidate significant features are those that at sorne
point along their length, exhibit geologie morphologie,
or vegetational expressions and characteristics that
provide a strong suggestion of youthful fault activity.
Non-significant features are those, which on the basis of
5-60
-
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....
--
-
-
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,_.
5.3.3.3
the aerial reconnaissance, apparently do not possess
geologie, morphologie, or vegetational characteristics
and/or expressions suggestive of youthful fault activity;
it was possible to identify non-fault-related origins for
many features in this category. Indeterminate features
are those lineaments that posses sorne geologie,
morphologie, or vegetational characteristics or
expressions that suggest the lineament may be a fault or
fault-related feature with the possibility of youthful
activity, but for which the evidence is not now
compelling •
Candidate Significant Features
The candidate significant and indeterminate features
identified during the first four phases of this task will
require further study in order to evaluate their
potential hazard to the proposed project facilities.
These features occur in three principal areas, which are
designated Areas A, B, and C {Figure 5-9) and are
discussed in the following sections. The features
presented in each area are discussed in terms of their
proximity and orientation with respect to the nearest
proposed project facility, previous mapping or published
studies in which they have been identified, their
expression on CIR photographs, and observations made
during the aerial reconnaissance phase of the study.
Area A
Area A is bounded by Mt. Spurr and the Chakachatna River
and Chakachamna Lake and Capps Glacier (Figure 5-9). Two
candidate significant features, SU 56 and CU 50, and two
indeterminate features, CU 52 and SU 150, are located
within this area.
5-61
Feature CU 50 is a curvilinar fault that trends roughly
east-west and extends from the mouth of the Nagishlamina
River to Alice Glacier, a distance of about 5 miles. The
western end of the feature is approximately 2 miles north
of the lake outlet. CU 50 was initially identified on
CIR photographs and is characterized by the alignment of:
(1) linear slope breaks and steps on ridges that project ~
southward from Mt. Spurr, east of Barrier Glacier,
with
{2) a linear drainage and depression across highly
weathered granitic rocks west of Barrier Glacier.
During the aerial reconnaissance, disturbed bedded
volcanic flows and tuffs were observed on the sides of
canyons where crossed by the feature east of Barrier
Glacier. These volcanic rocks are mapped as primarily
being of Tertiary age, but locally may be of Quaternary
age (Magoon and ethers, 1976). The possibility of the
disturbed volcanic rocks being of Quaternary age suggests
that CU 50 may be a youthful fault. The dense vegetation
west of Barrier Glacier prohibited close examination of
the fault in the granitic terrain.
CU 50 is classified as a candidate significant feature on
the basis of its close proximity to proposed project
facility sites and because it appears to displace
volcanic rocks that may be Quaternary in age.
Feature CU 52 is a composite feature that consists of a
fault mapped by Barnes (1966) and prominent morphological
features observed on CIR photographs. The feature tends
N63°E and extends along the mountain front from Capps
5-62
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-
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-
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-
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Glacier to Crater Peak Glacier, a distance of about 7.5
miles (Figure 5-9). The southwestern end of this feature
is approximately 8 miles from the outlet of Chakachamna
Lake. Along the northeastern portion of CU 52, from
Capps Glacier to Brogan Glacier, the feature is defined
by a fault that separates Tertiary granitic rocks from
sedimentary rocks of the Tertiary West Foreland formation
(Magoon and others, 1976). The southwestern segment,
from Brogan Glacier to the Crater Peak Glacier, which
extends the mapped fault a distance of 3 miles, was
identified on the basis of aligned linear breaks in
slope, drainages, and lithologie contrasts. During the
field reconnaissance, a displaced volcanic flow was
observed at the southwest end of the feature. Over most
of its length, the fault was observed to be primarily
exposed in bedrock terrain~ youthful lateral moraines
crossed by the fault did not appear to be affected.
This fault is considered to be a candidate significant
feature because of its prominent expression in the
Tertiary sedimentary and volcanic rocks crossed by the
fault and because of its close proximity to the proposed
project facili ties. In addition, the faul t may ex tend
farther to the west along the mountain front than was
observed on the CIR photographs or during the brief
reconnaissance. If such is the case, it may connect with
feature CU 50.
Feature SU 56 consists of two segments, a fault and a
lineament. The combined feature trends N78°E and can be
traced from the toe of Barrier Glacier to the edge of the
mesa like area between the Chakachatna River and Capps
Glacier, a distance of about 11 miles (Figure 5-9). The
western extent of the fault segment is unknown, but if
5-63
the lineament segment, defined by a linear depression
across the toe of Barrier Glacier is associated with the
fault, it may extend into and along the south side of
Chakachamna Lake, very near the proposed lake tap.
SU 56 was recognized on the CIR photographs on the basis
of the alignment of morphologie and vegetation features:
a linear depression across the piedmont lobe of Barrier
Glacier: a narrow linear vegetation alignment across the
alluvial fan east of and adjacent to Barrier Glacier;
small subtle scarps between Alice and Crater Peak
Glaciers~ and a prominent scarp and possibly a displaced
volcanic flow between Crater Peak and Brogan Glaciers.
During the field reconnaissance, all of the character-
istics observed on the CIR photographs could be
recognized with the exception of the vegetation alignment
east of Barrier Glacier. At two locations along the
feature, between Alice and Brogan Glaciers, displaced
volcanic flows and tuffs were observed. At both
localities the ~ense of displacement was down on the south
side relative to the north side. The amount of
displacement could not be measured due to the rugged
terrain at the two locations. At the eastern end of the
fault, near Brogan Glacier, the fault is on trend and
appears to connect with one of seven faults observed in
ridges along the eastside of Brogan Glacier where Barnes
(1966) mapped two prominent bedrock faults.
Feature SU 56 is classified as a candidate significant
feature because:
(1) it displaces volcanic rocks that may be of
Quaternary age;
5-64
•
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-
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"'-
.......
,_
-
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--
(2) the linear depression across tbe toe of Barrier
Glacier is on trend with the fault1 and
(3) the westward projection of the feature would pass
very close to the proposed project facilities along
the south side of Chakachamna Lake.
Feature SU 150 is composed of a series of parallel
west-to-northwest-trending faults mapped by Barnes
(1966). These faults are located on the Southwest side
of the mesa-like area between Brogan and Capps Glacier,
approximately 12 miles east of the outlet of Chakachamna
Lake (Figure 5-9) • These faults are exposed east of
Brogan Glacier along a nearly vertical canyon wall that
is deeply eroded into Tertiary sedimentary rocks mapped
as the West Foreland formation (Magoon and others, 1976) •
During the aerial reconnaissance, five additonal faults
were observed along the wall of the canyon, south of the
two faults mapped by Barnes (1966). Displacement on
these faults, as well as on the two mapped by Barnes
(1966), appears to be on the order of a few feet to a few
tens of feet, with the south side up relative to the
north side. An exception to this is the southernmost
fault, on which the displacement appears to be relatively
up on the north side. During the aerial reconnaissance,
the faults could not be traced for any appreciable
distance beyond their approximate length of 2 miles
mapped by Barnes (1966). The southernmost fault, which
is on trend with Feature SU 56, is probably an extension
of that feature.
5-65
The series of faults associated with Feature SU 150 are
included in this report as candidate significant features
because of the probable connection of the southernmost
fault in the series with Feature SU 56, which consists of
morphologie features that are suggestive of youthful
fault activity.
Area B
Area B includes the Castle Mountain fault and severa!
parallel lineaments (SU 49, SU 84, and CU 56, Figure
5-9) • The Castle Mountain fault is one of the major
regional faults in southern Alaska. It trends northeast-
southwest and extends from the Copper River basin to the
Lake Clark area, a distance of approximately 310 miles
(Beikman, 1980) • The Castle Mountain fault crosses the
mouth of the McArthur River Canyon near Blockade
Glacier. The Castle Mountain fault is reported to be an
oblique right-laterial fault with the north side up
relative to the south side (Grantz, 1966; Detterman and
ethers, 1974, 1976a, b).
The Castle Mountain fault is a prominent feature for most
of its mapped length. The segment northeast of the
Susitna River is defined by a series of linear scarps and
prominent vegetation alignments in the Susitna Lowlands
and lithologie contrast in the Talkeetna Mountains
(Woodward-Clyde Consultants, 1980; Detterman and others,
1974, 1976a). Between the Susitna and Chakachatna
Rivers, the fault is less prominent but is marked by a
series of slope breaks, scarps, sag ponds, lithologie
contrasts, and locally steeply dipping, sheared
sedimentary rocks that are generally flat to gently
dipping away from the fault (Schmoll and others, 1981;
5-66
·~
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--------------------------------~--------~~~~-------~~~-~-
,,_,
-
-
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-
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-
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,_
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-
,_
._
Barnes, 1966). Southwest of the Chakachatna River,
toward the Lake Clark area, the Castle Mountain fault is
well defined and expressed by the alignment of slope
breaks, saddles, benches, lithologie contrasts between
plutonic and sedimentary rocks, shear zones, and a
prominent topographie trench through the Alaska-Aleutian
Range Batholith (Detterman and ethers, 1976b).
Displacement on the Castle Mountain fault has been
occurring since about the end of Mesozoic time (Grantz,
1966). The maximum amount of vertical displacement is
about 1.9 miles or more (Kelley 1963: Grantz, 1966). The
maximum amount of right-lateral displacement is estimated
by Grantz (1966) to have been several tens of miles along
the eastern traces of the fault. Detterman and ethers
(1967 a,b) cited 10 miles as the total amount of right-
lateral displacment that has occurred along the eastern
portion of the fault and about 3 miles as the maximum
amount of right-lateral displacement that has occurred
along the western portion, in the Lake Clark area.
Evidence of Holocene displacement has only been observed
and documented along a portion of the Castle Mountain
fault in the Susitna Lowland (Detterman and ethers, 1974,
1976a). During their investigation, Detterman and ethers
(1974) found evidence suggesting that 7.5 ft. of dip-slip
movement has occurred within the last 225 to 1,700
years. The amount of horizontal displacement related to
this event is not know. However, Detterman and ethers
(1974) cited 23 ft. of apparent right-lateral displace-
ment of a sand ridge crossed by the fault. Bruhn (1979),
based on two trench excavations, reported 3.0 to 3.6 ft.
of dip-slip displacement, with the north side up relative
to the south side, along predominately steeply
5-67
south-dipping fault traces. He also reported 7.9 ft. of
right-lateral displacement of a river terrace near one of
the trench locations. ~
On the CIR photographs, the Castle Mountain fault is
readily recognizable on the basis of the alignment of
linear morphologie and vegetation features. The most
notable features were observed in areas where bedrock is
exposed at the surface and include: the prominent slope
break that occurs along the southside of Mount Susitna
and Lone Ridge; the prominent bench across the end of the
Chigmit Mountains, between the McArthur and Chakachatna
Rivers; and the alignment of glacial valleys in the
Alaska Range, one of which is occupied by Blockade
Glacier. In areas covered by glacial deposits, the
expression of the Castle Mountain is more subtle and is
dominantly an alignment of linear drainages, depressions,
elongated mounds, and vegetation contrasts and alignments.
Based on interpretation of the CIR photographs and aerial
reconnaissance observations, three lineaments (SU 49 and
portions of SU 84 and CU 56) are believed to be traces or
splays of the Castle Mountain fault. Lineament SU 49 is
approximately 4 miles long, trends northeast, and is on
line with the segment of the fault mapped between Lone
Ridge and Mount Susitna (Figure 5-9). SU 49 was
identified on the basis of the alignment of linear
drainages and saddles on a southeast-trending ridge with
a vegetation contrast in the Chakachatna River flood
plain and by a possible right-lateral affect or the east
facing escarpment along the west side of the Chakachatna
River.
5-68
.J
-
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-
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-
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-
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·-
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._
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Lineament SU 84 partially coincides with the mapped trace
of the Castle Mountain fault southwest of Lone Ridge. At
the Chuitna River, the mapped trace of the Castle
Mountain fault bends slightly to the north (Figure 5-9)
whereas lineament SU 84 continues in a more southwesterly
direction. Features along SU 84 that make it suspect are
the alignment of an elongate mound on trend with steeply
dipping sedimentary rocks exposed along the banks of the
Chuitna River and the eroded reentrant along the high
bluff on the northeast side of the Chakachatna River
(Nikolai escarpment) •
Lineament CU 56 is located east of Lone Ridge; it trends
N70°E, is 7 miles long, and is an echelon to the mapped ·
trend of the Castle Mountain fault. CU 56 was identified
on the CIR photographs on the basis of the alignment of
linear drainages and depressions and vegetation contrasts
and alignments. During the aerial reconnaissance, a
broad zone of deformed sedimentary rocks was observed on
the location where CU 56 crosses the Beluga River. This
locality coincides with a zone of steeply dipping
sedimentary rocks mapped by Barnes (1966).
Area C
Area C is located south to southeast of the proposed
project facilities sites, along the southeastern side of
the Chigmit Mountains between the North Fork Big River
and McArthur River (Figure 5-9) • Three prominent north-
east trending parallel features, SU 16, SU 22, and SU 23,
are located in this area. SU 16 is an inferred fault
that transverses both granitic bedrock and glacial
deposits. su 22 and SU 23 are primarily confined to the
granitic bedrock terrain.
5-69
Feature SU 16 is the longest of the three northeast-
southwest trending features 1ocated in Area c. This
feature extends from approximately the intersection of
the McArthur and Kustatan Rivers southwestward across a
broad bench and along the northeast trending segment of
the North Fork Big River, a distance of about 25 miles
(Figure 5-9) • SU 16 may extend even farther to the west
if it follows a very linear glacial valley that is ~
aligned with the northeast trending segment of the North
Fork Big River. The northern end of su 16 approaches to
within 10 miles of the proposed project facilities in
McArthur River area.
SU 16 was identified on the CIR photographs and aerial
reconnaissance on the basis of the alignment of elongate
low hills, linear depressions, vegetation contrasts,
prominent slope breaks, and a lithologie contrast that
form the broad bench like area between the North Fork Big
River and Kustatan Rivers. The southwestern segment of
the fracture .is defined by the alignment of a linear
portion of the North Fork Big River and a linear glacial
valley north of Double Peak. During the aerial
reconnaissance, no distinctive evidence, such as
displaced lithologie units or bedding or scarps, was
observed to confirm that SU 16 is actually a fault.
Nonetheless, morphologie features that were observed do
suggest that SU 16 is a fault and that it may be a
youthful fault.
SU 16 is included in this report as a candidate
significant fault because the morphologie fedtures
observed on the CIR photographs and during the aerial
reconnaissance strongly suggest that it is a fault and
may be a youthful fault.
5-70
.y
""""'
-
....
-
"-
-
-
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'-
Features SU 22 and SU 23 (Figure 5-9} are both northeast
trending linear to curvilinear faults that parallel one
another at a distance of about one mile. Feature SU 22
can be traced from about the McArthur River southwestward
to Black Peak, a distance of about 16 miles. Feature SU
23 is approximately 8 miles in length and extends from
Blacksand Creek southwestward to the north Fork Big River
area. The northeastern ends of the two features (SU 22
and SU 23) approach to within 8 miles of proposed project
facility sites in the McArthur River area. Both features
were recognized on CIR photographs and are defined by the
alignment of prominent linear troughs that are partially
occupied by small lakes and ponds, scarps, slope breaks,
benches, and saddles.
During the aerial reconnaissance, the two features could
be readily traced across bedrock terrain (mapped as
Jurassic to Cretaceous-Tertiary granitic rock; Magoon and
others, 1976} on the basis of their morphologie
features. Slicken-sided and polished surfaces were
observed at several of the scarps and slope break
localities examined; sheared zones were also observed
during the reconnaissance. The southwestern portions of
both features are located in very rugged terrain and are
poorly defined due to the highly jointed granitic rocks
that are present along this segment.
At the northern end, in the vicinity of Blacksand Creek,
SU 23 appears to splay out with one trace trending toward
su 22 and one trace trending toward SU 16 (Figure 5-9).
SU 22 also appears to die out in the vicinity of
Blacksand Creek, although there was a subtle tonal
alignment observed on the CIR photographs on the north
side of the creek that suggests it may extend across
Blacksand Creek toward the McArthur River.
5-71
SU 22 and SU 23 are included as candidate significant
features because their prominent expression suggests that
they are major structures and that they may be associated
with SU 16 which is considered a fault with possible
youthful activity.
Area D
Area D (Figure 5-9) includes the Bruin Bay fault, which
is one of the major regional faults in southern Alaska.
The Bruin Bay fault is a northeast-trending, moderate-to-
ste~ply-northwest-dipping reverse fault that extends
along the northwest side of the Cook Inlet from near
Mount Susitna to Bechalaf Lake, a distance of about 320
miles (Detterman and ethers, 1976b) • The fault
approaches as close as approximately 30 miles south to
southwest of the proposed project facilities at
Chakachamna Lake and approximately 20 miles of the
project facilities in the McArthur River.
The northern segment of the Bruin Bay fault, from about
the.Drift Rive~ area to Mount Susitna, is projected
beneath surficial deposits from its last bedrock exposure
north of Katchin Creek. The projection is based on a
prominent linear depression across Kustatan Ridge,
alignment of linear lakes and depressions in the lowland
area west and north of Tyonek, and highly distur~ed and
faulted Teritiary sedimentary rocks along the Chuitna and
Beluga River (Detterman and ethers, 1976b; Magoon and
others, 1976; Schmoll and others, 1981). To the south of
Katchin Creek, where the fault is exposed in bedrock
areas, the trace of the fault is commonly marked by a
zone of crushed rock a few to several hundred meters wide
and saddles or notches (Detterman and ethers, 1976b).
5-72
-
---------------------------------------------------------------------------------------=--------~--------=----·~
-
"-
·-
-
-
The sense of displacement along the fault is reverse with
the north side up relative to the south side (Magoon and
others, 1976; Detterman and others, 1976b). Detterman
and Hartsock (1966) reported left-lateral displacement of
6 miles or less has occurred along the fault in the
Iniskin-Tuxedni region, southwest of the study area. The
youngest unit reported displaced by the Bruin Bay fault
is the Tertiary sedimentary Beluga formation (Magoon and
others, 1976). No displacement of Holocene surficial
deposits between Katchin Creek and the probable junction
of the fault with Castle Mountain fault near Mt. Susitna
has been observed or documented (Detterman and others
1976b; Detterman, personal communication, 1981).
During the analysis of the CIR photographs, several
subtle to prominent discontinuous lineaments were
identified along the projected trend of the Bruin Bay
fault across the McArthur and Chakachatna River flood
plains near the Cook Inlet, and along the lowland area
west of Tyonek. The lineaments were examined during the
aerial reconnaissance and no displacement or disturbed
Holocene deposits were observed. Several of the
lineaments, however, did coincide with disturbed or
faulted sedimentary rocks of the Beluga formation exposed
along the Chuitna and Beluga Rivers. Further work is
needed to assess whether the glacial and/or fluvial
deposits overlying the sedimentary bedrock have been
faulted or disturbed.
Although no evidence has been observed or reported that
would indicate youthful fault activity along the Bruin
Bay fault, several of the lineaments observed on the CIR
photographs are suggestive of youthful fault activity.
On the basis of the lineaments along the projected trace
5-73
5.3.3.3
of the Bruin Bay fault, and the fact that the fault is
suspected to intersect with the Castle Mountain fault,
the Bruin Bay fault is considered for this report to be a
candidate significant feature.
Implications with Respect to the Proposed Hydroelectric
Project
Based on the results of the work to date a preliminary
assessment can be made regarding the potential surface
faulting hazards and seismic sources of ground motion
(shaking) with respect to the proposed project site.
(1) Within the study area, faults and lineaments in four
areas have been identified for further evaluation in
order to assess and better understand their
potential effect on project considerations. For
example, if feature SU 56 is an active fault, its
trend is toward the area proposed for the lake tap
and the extent and activity of this feature clearly
require evaluation. Several of these features may
prove to be capable of producing earthquakes, thus
both ground shaking and surface rupture in the
project area.
(2) The Castle Mountain fault is located along the
southeast side of the Chigmit Mountains at the mouth
of McArthur Canyon. Although no displacements of
Holocene deposits have been observed or reported for
the segment of the Castle Mountain fault between the
Susitna River and the Lake Clark area, the fault is
considered an active fault on the basis of the
reported displacement of Holocene deposits east of
the project area in the vicinity of the Susitna
River.
5-74
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.....,
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,_
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-
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'.,_.
,_
-
·-
(3) Based on a review of the available literature and
detailed studies conducted for major projects in
southern Alaska there are three potential seismic
sources that may have an effect on the project
site. These include: the subduction zone, which
consists of the Megathrust and Benioff zone; crustal
seismic zone; and severe volcanic activity. The
Castle Mountain fault (crustal seismic source) and
the Megathrust segment of the subduction zone are
expected to be the most critical to the project with
respect to levels of peak ground acceleration,
duration of strong shaking, and development of
response spectra.
References
Barnes, F. F., 1966, Geology and coal resources of the
Beluga-Yentna Region, Alaska: u.s. Geological Survey
Bulletin 1202-C, 54 p.
Beikman, H. M., compiler, 1974, Preliminary geologie map
of the southeast quadrant of Alaska: u.s. Geological
Survey Miscellaneous Field Studies Map MF-612, scale
1:1,000,000.
Beikman, H. M., compiler, 1980, Geologie map of Alaska:
u.s. Geological Survey, scale 1:2,500,000.
Bruhn, R. L., 1979, Holocene displacement measured by
trenching the Castle Mountain fault near Houston,
Alaska: Alaska Division of Geological and Geophysical
Surveys, Geological Report 61, 4 p.
5-75
Bureau of Reclamation, Chakachamna Project Alaska -
Status report March, 1962: Bureau of Reclamation, Alaska
District Office, Juneau, Alaska, unpublisheà report, 21 p.
Capps, S. R., 1935, The southern Alaska Range: u.s.
Geological Survey Bulletin 862, 101 p.
Detterman, R. L., and Hartsock, J. K., 1966, Geology of
the Iniskin-Tuxedni Region, Alaska: u.s. Geological
Survey Professional Paper 512, 78 p.
Detterman, R. L., Plafker, G. Hudson T., Tysdal, R. G.,
and Pavoni, N. 1974, Surface geology and Holocene breaks
along the Susitna segment of the Castle Mountain fault,
Alaska: u.s. Geological Survey Miscellaneous Field
Studies Map MF-618, scale 1:24,000.
Detterman, R. L., Pl~fker, G., Tysdal, R. G., and Hudson,
T., 1976a, Geology and surface features along part of the
Talkeetna 9egment of the Castle Mountain-Caribou fault
system, Alaska: u.s. Geological Survey Miscellaneous
Field Studies Map MF-738, scale 1:63,360.
Detterman, R. L., Hudson, T., Plafker, G., Tysdal, R. G.,
and Hoare, J. M., l976b, Reconnaissance geologie map
along the Bruin Bay and Lake Clark faults in Kenai and
Tyonek quadrangles, Alaska: u. s. Geological Survey
Open-File Report 76-477, 4 p., scale 1:250,000.
Giles, G. c., 1967, Barrier Glacier investigations and
observations in connection with waterpower studies: u.s.
Geological Survey, unpublished report, 61 p.
5-76
~
,_
-
"-
. .....,
' ·-
-
Grantz, Arthur, 1966, Strike-slip faults in Alaska:
U.S. Geological Survey Open-File Report, 82 p.
Hastie, L. M., and Savage, J. C., 1970, A dislocation
model for the Alaska earthquake: Bulletin of the
Seismological Society of America, v. 60, p. 1389-1392.
Hunt, C.B., 1967, Physiography of the United States: w.
H. Freeman and Co., San Francisco, 480 p.
Jackson, B. L., 1961, Potential waterpower of Lake
Chakachamna, Alaska: u. s. Geological Survey Open-File
Report, 20 p.
Johnson, A., 1950, Report on reconnaissance of Lake
Chakachamna (sic), Alaska: u. S. Geological Survey Open-
File Report, 8 p. plus plates.
Juhle, w., and Coulter, H., 1955, The Mt. Spurr eruption,
July 9, 1953: Transactions, American Geophysical Union,
v. 36, no. ~, p. 199-202.
Karlstrom, T. v., 1964, Quaternary geology of the Kenai
lowland and glacial history of the Cook Inlet region,
Alaska: u. s. Geological Survey Professional Paper 443,
69 p.
Karlstrom, T. v., Coulter, H. w., Jernald, A. T.,
Williams, J. R., Hopkins, D. M., Drewes, H., Huller, E.
H., and Candon, w. H., 1964, Surficial Geology of
Alaska: u. S. Geological Survey Miscellaneous Geologie
Investigation Map I-557, scale 1:1,584,000.
5-77
Kelley, T. E., 1963, Geology and hydrocarbons in Cook
Inlet Basin, Alaska, in Childs, D. E., and Beebe, B. w.,
eds., Backbone of the Americas Symposium: American
Association of Petroleum Geologists Memoir 2, p. 278-296.
Lahr, J. c., and Stephens, c. D., 1981, Review of
earthquake activity and current status of seismic
monitoring in the region of the Bradley Lake
Hydroelectric Project: u. s. Geologica.Survey Report,
prepared for the Department of the Army, Alaska District,
Corpos of Engineers, 21 p.
Lamke, R. D., 1972, Floods of the summer of 1971 in
southcentral Alaska: u. s. Geological Survey, Water
Resources Division, Alaska District, Open-File Report, p.
30-31.
Magoon, L. B., Adkison, w. L., and Egbert, R. M., 1976,
Map showing geology, Wildcat Wells, Tertiary plant fossil
localities, K-Ar age dates, and petroleum operations,
Cook Inlet area, Alaska: u. s. Geological Survey Map
I-1019, scale 1:250,000.
McCann, w. R., Perez, O. J., and Sykes, L. R., 1980,
Yakataga Gap, Alaska: Seismic history and earthquake
potential: Science, v. 207, p. 1309-1314.
Miller, R. D., and Dobrovolny, E., 1959, Surficial
geology of Anchorage and vicinity, Alaska: u. s.
Geo1ogical Survey Bulletin 1093, 128 p.
National Oceanic and Atmospheric Administration, 1981,
Hypocenter Data File Period of Coverage 1929 to 1980:
Environmental Data Services, Boulder, Colorado.
5-78
-----------------~-----------~--~--~~----------------~~--------~--~---------·----------
......
,_,.
:~
-
~
-
.....
-
-
~~
Pewe, T. L. Hopkins, D. M., and Giddings, J. L., 1965,
The Quaternary geology and archeology of Alaska: in
Wright, H. E. and Frey, D. G., eds., The Quaternary of
the United States, Princeton University Press, Princeton,
p. 355-374.
Pewe, T. L., 1975, Quaternary geology of Alaska: u.s.
Geological Survey Professional Paper 835, 145 p.
Plafker, G., 1969, Tectonics of the March 27, 1964,
Alaska Earthquakes: u. s. Geological Survey Professional
Paper 543-I, 74 p.
Porter, s. C., and Denton, G. H., 1967, Chronology of
Neoglaciation in the North American cordillera: American
Journal of Science, v. 265, p. 177-210.
Post, A., 1969, Distribution of surging glaciers in
western North America: Journal of Glaciology, v. 8, no.
53, p. 229-240.
Post, A., and Mayo, L. R., 1971, Glacier dammed lakes and
outburst floods in Alaska: u. s. Geological Survey
Hydrologie Investigations Atlas HA-455.
Richter, c. F., 1958, Elementary seismology: San
Francisco, Freeman Press, 768 p.
Schmoll, H. R., Szabo, B. J., Rubin, M., and Dobrovolny,
E., 1972, Radiometrie dating of marine shells from the
Bootlegger Cove clay, Anchorage area, Alaska: Bulletin,
Geological Society of America, v. 83, p. 1107-1114.
5-79
Schmoll, H. R., Yehle, L. A., Gardner, C. A., 1981,
Preliminary geologie map of the Congahbuna area, Cook
Inlet Region, Alaska: u. s. Geological survey Open-File
Report 81-429, 8 p.
Schmoll, H. R., Pasch, A. D., Chleborad, A. F., Yehle, L.
A., and Gardner, C. A., in press, Reconnaissance
engineering geology of the Beluga Coal resources area,
south-central Alaska, in Rao, P. D., ed., Focus on
Alaska's Coal '80, Conference, Fairbanks, Alaska,
Proceedings: Fairbanks, University of Alaska, School of
Mineral Industry MIRL Report No. 47.
Slemmons, D. B., 1977, State-of-the-art for assessing
earthquake hazards in the United States; Part 6: Faults
and earthquake magnitude with Appendix on geomorphic
features of active fault zones: u. s. Army Engineering
Waterways Experiment Station, Vicksburg, Contract No.
DACW 39-C-0009, 120 p.
Slemmons, D. B., 1980, Letter toR. E. Jackson, Nuclear
Regulatory Commission, dated 5 November 1980 and errata,
dated 4 December 1980, in San Onofre Nuclear Generating
Stations Units 2 and 3, Safety Evaluation Report,
NUREG-0712, Appendix E, p. El-E28.
Sykes, L. R., 1971, Aftershock zones of great earth-
quakes, seismicity gaps, and earthquake prediction for
Alaska and the Aleutians: Journal of Geophysical
Research, v. 76, p. 8021-8041.
Tarr, R. s., and Martin, L., 1912, The earthquakes at
Yakutat Bay, Alaska in September 1899: u. s. Geological
Survey Professional Paper 69, 135 p.
5-80
llliolllil
-
-
-----------------------~ -........wt ........,.
,_
"""'
-
-
:_.
-
-
-
-
TenBrink, N. w., and Ritter, D. F., 1980, Glacial
chronology of the north-central Alaska Range and
implications for discovery of early man sites:
Geological Society of America, Abstracts with Programs,
1980, p. 534.
TenBrink, N. w., and Waythomas, c. F., in preparation,
Late Wisconsin glacial chronology of the north-central
Alaska Range - a regional synthesis and its implications
for early man settlements.
Thatcher, w., and Plafker, G., 1977, 1899 Yakutat Bay,
Alaska Earthquakes: Seismograms and Crustal Deformation
(Abs.): Geological Society of America Abstracts with
Programs, v. 9, p. 515.
Trainer, F. w., and Waller, R. M., 1965, Subsurface
stratigraphy of glacial drift at Anchorage, Alaska: u. s.
Geological Survey Professional Paper 525-D, p. Dl67-Dl74.
u. s. Geological Survey, 1980, Volcano Log: Mount St.
Helens, 1980, Spall, H., (ed.), in Earthquake Information
Bulletin: u. s. Geological Survey, July-August 1980, v.
12, no. 4, p. 142-149.
Williams, J. R., and Ferrinas, o. J., 1961, Late
Wisconsin and recent history of the Matanuska Glacier,
Alaska: Arctic, v. 14, no. 1, p. 83-90.
Woodward-Clyde Consultants, 1978, Offshore Alaska seismic
exposure study: Prepared for Alaska Subarctic Operators'
Committee (ASOC), March, 1978, v. 1 through 5.
5-81
Woodward-Clyde Consultants, 1979, Reconnaissance Geology,
Bradley Lake Hydroelectric Project: Contract No. DACW
85-79-C-0045, Department of the Army, Alaska District,
Corps of Engineers, 65 p.
Woodward-Clyde Consultants, l980a, Seismi~ity Study
Bradley Lake Hydroelectric Project: Contract No. DACW
85-79-C-0045 Modification POOOl, Department of the Army,
Alaska District, Corps of Engineers, 35 p.
Woodward-Clyde Consultants, 1980b, Interim Report on
Seismic Studies for Susitna Hydroelectric Project for
Acres American ~ncorporated: Alaska Power Authority,
Susitna Hydroelectric Project, Subtask 4.01 through 4.08.
Woodward-Clyde Consultants, 1981, Draft Report Bradley
Lake Hydroelectric Project Design Earthquake Study:
Contract No. DACW 85-79-C-0045 Modification 0005,
Department of the Army, Alaska District, Corps of
Engineerp, 53 p.
5-82
ENVIRON MENT AL
STUDIES
6.0
·-
-
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ENVIRONMENTAL STUDIES
As described previously, one component of the Chakachamma
Project Feasiblity Study is an environmental evaluation
of the natural and human resources. To accomplish the
evaluation, the environmental studies were divided into
four disciplines: environmental hydrology, acqùatic
biology, terrestrial biology, and human resources. The
objectives of this feasibility study are to:
o obtain sufficient information on the environment of
the study area to identify constraints that may be
placed on the project, potentially affecting its
feasibility; and
o obtain sufficient information to prepare the required
environmental exhibits for the FERC license
application.
To meet these objectives a two phase program has been
designed. Phase I consists of a reconnaissance-leve!
survey conducted during the fall season of 1981. This
survey provides a more thorough understanding of the
study area, and bence allow a more appropriate design of
1982 Phase II studies.
During 1981, there were two reconnaissance efforts. The
first overview was conducted in August by the task lead-
ers of the biological and hydrological disciplines. The
objective of the August site visit was to document the
presence of sockeye salmon in the major project waters
and to survey the site in preparation for the fall
reconnaissance. The second investigation was carried out
in mid-September and involved two weeks of field data
6-1
6.1
collections. The objectives of this effort were to
obtain sufficient information and understanding of the
study· area and its resources to allow for the design of
more detailed 1982 studies and to assess, in a
preliminary nature, the overall environmental assessment
of the conceptual designs of the project alternatives.
Coincident with the 1981 field studies were ongoing
reviews of the literature and discussions with key agency
and native corporation personnel.
Specifie objectives and preliminary results of the 1981
environmental investigations by each discipline are
presented in the following parts of this section.
Preliminary conclusions are based on data obtained from
agency personnel, available literature, and the limited
information collected during the fall reconnaissance
programs.
Preliminary assessments of anticipated environmental
impacts associated with each project alternative are
presented in Section 7, while descriptions of conceptual
work plans for 1982 programs are presented in Chapter 10.
Environmental Study Area
The study area is located on the west side of Cook Inlet
approximately 60 miles west of Anchorage (Figure 6.1).
This region supports a wide variety of biological and
visual resources, and is bordered by the Alaska Mountain
Range on the west and Upper Cook Inlet on the east.
Administration of the lands and waters of the area come
under the jurisdiction of the u.s. Fish and Wildlife
Service, the National Park Service, the Alaska Department
of Fish and Game, the Alaska Department of Natural
6-2
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Resources, and two native corporations (Cook Inlet Region
and Tyonek Native). Although management of the area is
complex due to the multitude of organizations responsible
for the area, specifie sites within the study area have
specifie management objectives. While the Trading Bay
State Game Refuge is maintained to protect waterfowl and
provide sport hunting, the Lake Clark National Park's
principal objective is to maintain the ecosystem in as
nearly pristine a condition as possible. Research in
both areas involves documenting pristine conditions and
processes, and determining the stability of the
ecosystems. In c'ontrast to refuge and park objectives,
the native corporations manage their lands for high yield
timber harvesting and maintenance of subsistence
resources.
Between the mountains and the tidal flats in Trading Bay,
the land is flat and drainage is poor. Throughout these
lower elevations of the project area, the absence of
relief has contributed to the formation of a continuous
a~ray of marshes, bogs, and ponds. Two major rivers
transport the water from the mountains to the inlet,
collect runoff from adjacent marshes and bogs, and
provide both migration and spawning habitat for numerous
species of resident and anadromous fish. The first of
these major rivers, the McArthur, has its origin at
McArthur Glacier, yet receives the majority of its water
from Blockade Glacier. The second major waterway is the
Chakachatna River. Or.iginating at the outlet of
Chakachamna Lake, the river flows east about 15 miles
through a canyon containing almost continuous rapids and
few pools. .Once on the low flatlands, the Chakachatna
floodplain gets substantially larger until jt reaches its
divergence from Noaukta Slough, after which it becomes
6-3
6.2 ,,,
6.2.1
much narrower. The Noaukta Slough carries a large
proportion of the flow from the divergence as it fans out
into a two mile wide tangle ~f inteilaced channels before
it joins the McArthur River. Downstream from this
confluence, the McArthur flows several miles to the
Chakachatna River confluence, after which it passes
through marshes and tidal flats before reaching Trading
Bay.
Chakachamna Lake and its tributaries, the Nagishlamina
River, the Chilliga~ River, and Kenibuna Lake are located
in the higher elevations of the study area above the
Chakachatna River. As with the rest of the project area,
these high elevation lands and waters support a variety
of fish and wildlife. Chakachamna Lake is approximately
350 feet deep with mountains rising 3000 to 4000 feet
above its steep, rocky shoreline. At the mouths of the
major tributaries are large deltas, composed mainly of
sand and glacial-fluvial deposits.
Environmental Hydrology
Background
The overall objectives of the environmental hydrology
studies for the Chakachamna Hydroelectric Project are to:
o assess the impacts of flow regulation on the physical
characteristics of the Chakachatna and McArthur River
systems and
o provide input to the biological and socioeconomic
impact analysis investigations.
6-4
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Studies conducted to date for this interim report have
addressed bath of these objectives to a reconnaissance
level.
Data Base
There have been
studies. c·onducted
development of
~~L~~i:,~i~:t.~;n; t o the
studies have been conducted on the Chakachatna River flow
regime to evaluate the: .. :potential f.or hydropower using
these flows~ these studdceswere first reported in 1950
and were investigated in ~~re det~il in the 1960's.
Section 4 + 0 of this reg().Et S<l.lmmariz.es the current level
of knowledge of the; fLewa .à'Vâ,i.lab:Le fer hydropower
:-?~;..;, -
generation •.
" . ;; ,• .<i~~~-~~;2-~~~t:~-·~;':{·~-"~>'.'::·~·~!-~,~~::ç ··::"'tg~f::'""1~~-;,_·~·-·";.·:·. ''~{:'.-'" Mr. Robert D. Lamkexr· Cliitl~~Ji'fl1M.·:.~.E!'!i1~~.~ Sect~on of
the Water Resource·~ Df~~~-~~{$~~''hi~~}"~J~.~~~palrtmént of
Interior Geological .. su,bey;i'"i:>-rovilàîed flow data and
standard hydrologie.; amüyses for Ûse in this
investigation. Hydrol.og.ic:1data for> engineering purpose:s
are presented in Section 4.0 of this report. Sorne of
these analyzed data. wer.e us:e.d in the environmental
hyd.cology evaluations;.
Study Area
The study area was described in the previous section.
The major areas studied during the environmental
hydrology reconnaissance investigation included:
o Three areas near the mouths of the major tributaries
to Chakachamna Lake; Shamrock Glacier Rapids (A, Fig.
6-5
6.2.2
6.2), Chilligan River (B, Fig. 6.2), and Nagishlamina
River (C, Fig. 6.2).
o Four areas along the Chakachatna River (D through G,
Fig.6.2).
o Two areas along Middle River (F and H, Fig. 6.2).
o Eight areas along the McArthur River (I through P,
Fig.6.2).
o Two areas of Noaukta Slough Channels at their
confluence with McArthur River (0 and P, Fig. 6.2).
Other .areas along the streams that may be impacted by the
project were also investigated, but in less detail.
Study Objectives and Methodology
The specifie objectives of the environmental hydrology
reconnaissance study leading to this interim report were
to:
o collect sufficient quantitative and qualitative data
to make a preliminary assessment of the physical
impacts related to each of the project alternatives,
and
o provide input to preliminary assessments of biological
and socioeconomic impacts related to each of the
project alternatives
These objectives were met through a combination of field
data collection and office evaluations, as described in
the following sections:
6-6
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Hydrology
Field Data Collection. Hydrologie field data that were
collected during the two week field reconnaissance
include:
o discharge measurements,
o lake water level survey, and
o wetland/river level surveys.
Discharge measurements were taken at study locations D,
F, G, H, I, K, L, and M (Figure 6.2) using procedures
similar to those of the o.s. Geological Survey; however,
for expediency during this brief reconnaissance, only
about 10 measuring stations were used in each channel. A
Marsh-McBirney flow meter was used to measure velocity at
a depth equal to 60 percent of the full depth.
A survey was conducted at Chakachamna Lake to establish
the lake surface elevation at the time of the survey.
Vertical angle measurements were taken from Bench Mark
MORE {on the south side of the lake mid-way along the
lake) to the lake water level. A Topcon DMS-1 electronic
distance measurement system was used to measure distances.
Standard differentiai leveling techniques were used to
measure the difference between the water level in a
wetland and the water level in a channel of the Noaukta
Slough a short distance downstream from study area E
(Figure 6.2). An approximate method using a band level
was used in study area H (Figure 6.2) to evaluate the
water level difference between a wetland and Middle River.
6-7
Office Evaluations. Office evaluations were conducted to
develop approximate hydrologie data at eight locations in
the study area (numbered locations, Figure 6.2).
Developed data include:
o natural mean monthly flows,
o mean annual flows for natural flow conditions,
o natural flood flows at selected locations
o natural low flow conditions at selected locations.
In addition, instream flow requirements for maintaining
fisheries habitat were calculated on a monthly basis at
the outlet of Chakachamna Lake. All office evaluations
were selected to provide reasonable estimates of flow
conditions for the purpose of making preliminary impact
assessments.
Natural mean monthly flows were estimated from the
relations shown in Table 6.1 and the following
assumptions:
o mean monthly flows per square mile based on calculated
Chakachamna Lake inflows (from Section 4.0) are
representative of those from mountainous areas,
o mean monthly flows per square mile based on the 4 year
average of mean monthly flows of the Chuitna River
{Station 152944501 are representative of those from
non-mountainous areas, and
o proportions of flow in downstream channels at each
divergence is the same as the proportion of flow in
those channels at the time of the reconnaissance
measurement.
6-8
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Table 6.1. Relations used in calculating natural mean monthly flows
at eight representative locations.
Location
Numbera
1
2
3
4
5
6
7
8
River Relationb
Chakachatna Qml = U.S.G.S. data for Cha.kachatna River
near Tyonek (15294500)
Chakachatna Qm 2 = Qml + A1 _2 x (B+C)/2
Cha.kachatna Qm 3 = om 2 + 0.913A 2 _3 x (B+C)/2 +
0.087 A2 _3 x C
Chakachatna Qm 4 = 0.084 Qm 3 + (0 B4 A3 _0 + An-4)
x c
Middle
Upper
McArthur
McArthur
McArthur
QmS = 0.016 Qm 3 + (0.16 A3 _0 + A 0 _5 )
x c
Qm6 -= A6 x B
Qm7 = Om6 + A6-7 x B
0m8 = Qm7 + A7-8 x C + 0.90 Qm3
asee Figure 6.2 for locations
bQmi = mean monthly flow for any month at location i
6-9
---------------
Ai-j = contributing drainage area between locations i
and j; a D subscript r@presents the location of the
divergence of Chakachatna and Middle Rivers
B = mean monthly flow per square mile based on calculated
Chakachamna Lake inflows
C = mean monthly flow per square mile based on the 4 year
average of mean monthly flow of the Chuitna River
(Station 15294450)
Mean annual flows were calculated from the calculated
mean monthly flows on a weighted average method; the
weighting was based on the number of days in each month.
For example, mean January flow would be multiplied by
31/365 to obtain the January portion of the mean annual
flow.
The natural flood flows were calculated based on a
regional flood frequency analysis (Lamke 1979). The
drainage area, percentage of lakes and percentage of
forest cover, were obtained for each location from
1,250,000 scale topographie maps; Lamke's (1979) isoline
maps were used to obtain mean annual precipitation and
minimum January temperature. A weighted average for
these parameters wa~ used for locations 4, 5, and 8 based
on the percentage of flow carried by each channel
downstream from divergences as measured during the
reconnaissance.
6-10
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The natural low flow conditions along the Chakachatna
River were estimated using on the low flow conditions per
square mile from the Chakachatna River gaging station
records. The low flow analyses of the gage records were
provided by the u.s. Geological Survey.
Mitigative releases for fisheries were calculated using
different methods for the McArthur and Chakachatna River
powerhouse alternatives. The results of these analyses
are presented in Section 7. For the alternatives with
the powerhouse on the McArthur River, fisheries habitat
down the entire length of the Chakachatna had to be
considered.
The method selected to estimate the instream flow
requirements for this preliminary assessment is called
the Montana Mlthod (Tennant 1975) • Several major
assumptions had to be made when using the Montana Method;
these include:
o that the method is valid for a complex stream system
like the Chakachatna River,
o that the seasonal flow regimes postulated in the madel
are appropriate for south-central Alaska, and
o that the method is appropriate for the complex of
anadromous and resident salmonids found in the
Chakachatna River.
The instream flow requirements using this method are
based on a percentage of the mean annual flow. The
percentage is based on observations that the wetted
perimeter of a stream (potential usable habitat)
6-11
typically increases rapidly with increasing discharge up
to a flow equal to 30 percent of the mean annual flow.
For higher discharges, the wetted perimeter increases
less rapidly. Tennant (1975) refers to minimum
instantaneous flows of 30 percent of the mean annual flow
as "good" flow. The method also calls for two different
seasonal flow regimes, a low flow period from October
through March and a higher flow period from April through
September. "Fair" to "good" flows can be obtained if 10
and 30 percent of the mean annual flow is maintained
during the low flow and higher flow periods,
respectively. These percentages were used to estimate
what instream flow needs to be maintained for the fishery
resource. The natural flow during the low flow period is
periodically less than the recommended flows; natural
flows were assumed to be released in these situations.
The required flow for the fishery resource is different
for the alternatives with the powerhouse on the
Chakachatna River. For thêse alternatives, the dewatered
section of the Chakachatna River is in the canyon; this
dection of river apparently provides primarily migratory
habitat and relatively small amounts of spawning and
rearing habitats. Thus, it was assumed that maintenance
of the migratory habitat is sufficient to mitigate the
major impacts of dewatering this section of stream.
It was assumed that a 30 cfs flow release would be
adequate to maintain a sufficient migratory pathway
between the powerhouse and the lake, possibly requiring
sorne channelization.
6-12
'1111111'
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6.2.2.2
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-
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-
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Hydraulics
Field Data Collection. Hydraulic data that were
collected during the field reconnaissance include:
o stream and floodplain transects,
o stream gradients, and
o lake bottom profiles.
The stream and floodplain transect data were collected
using one or a combination of the following methods:
o using transit and electronic distance measuring
equipment to get horizontal and vertical angles and
distances to locations along the transect,
o using discharge measurement data to represent the
transect below water level, and
0 using a Raytheon DE-7198 depth recorder mounted to a
boat to represent the transect below water level in
streams too deep or swift to wade.
Sorne transects consist only of the portion of the
transect below water level.
Stream gradients were surveyed using a transit and
electronic distance measuring equipment. water surface
profiles typically were surveyed, although bed profiles
also were surveyed at the lake tributary study areas.
6-13
Lake bottom profiles were collected using a Raytheon DE
719B depth recorder. Horizontal control was provided in
an approximate manner by relating to terrain features and
by monitoring boat speed.
Office Evaluation. Hydraulic office evaluations were
conducted to provide estimates of the following types of
information:
o hydraulic geometry (width, depth, and velocity as a
function of discharge) and
o flooding and backwater characteristics.
The hydraulic geometry as defined above was calculated
using the Manning equation. Input data to the equation
include channel geometry and energy gradient that were
obtained from the stream and floodplain transects and
water surface profiles that were measured in the field.
Manning roughness coefficients were estimated by
back~calculating values from discharges measured or
estimated in the field and checking the reasonableness
based on previous experience.
Flooding is estimated at selected transect locations by
establishing the stage (water level) corresponding to the
calculated flood discharge from the hydraulic geometry
data. Areal extent of flooding between transects is
qualitative and based on aerial photographs and field
observations. Backwater characteristics in tributaries
are described qualitatively based on a review of flood
levels and surveyed stream gradients.
6-14
J -
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6.2.2.3
_,
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Channel Configuration and Process
Field Data Collection. Data collected during the field
reconnaissance pertaining to channel configuration and
process include:
o observations of channel configuration,
o observations of lateral migration activity,
o observations of sedim~nt transport characteristics.
o stream substrate
o potentia1 fish overwintering area location surveys, and
o fish spawning channel location surveys.
The latter two data types were collected in prepara~ion
for fish overwintering studies planned for early in 1982.
The observations of channel configurâtion, lateral
1
migration activity and sediment transport characteristics
were qualitative and were based on the experience of the
environmental hydrologist. Stream substrate was described
qualitatively and documented in sorne cases with
photographs. The surveys conducted to establish the
location of selected potential fish overwintering areas
and identified fish spawning channels used a combination
of transit, electronic distance measuring deviees, tape,
and magnetic compass. Surveys were referenced to
temporary benchmarks established for this survey. The
results of these surveys are not presented later in this
6-15
6.2.3
6.2.3.1
report since they were collected only for use in later
field investigations.
Office Evaluations. Channel configuration, lateral
migration activity and sediment transport characteristics
were qualitatively evaluated for natural stream flows.
The data used to evaluate these characteristics include
the hydraulic cha.racter istics discussed previously,
aerial photographs, and field observation. These
preliminary evaluations were qualitative and the results
are descriptive.
Results and Discussion
The results of this reconnaissance level investigation
are preliminary. Certain assumptions have been made to
enable a comparison of alternatives; these assumptions
will be checked during the more detailed investigations
planned for 1982.
The results of the field reconnaissance and office
evaluations for the current natural conditions are
presented and discussed below.
Hydrology
The locations, date, and results of discharge measure-
ments during the fall reconnaissance are summarized in
Table 6.2. Estimates of mean monthly and mean annual
flows at eight representative locations in the study area
are presented in Table 6.3. A comparison of measured
values with mean monthly values indicates that the flow
at the time of the survey generally was less than the
mean for September. The flow generally was decreasing
throughout the two week reconnaissance. The discharge
6-16 ~
-·
·-
-
-
'-
~
-
'-
-
-
-
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measurements indicate that approximately 90 percent of
the Chakachatna River flow goes through Noaukta Slough.
The remaining 10 percent flows to the Chakachatna and
Middle River divergence where approximately 84 percent of
this flow remains in the Chakachatna River and 16 percent
flows down Middle River. This flow distribution was
assumed to remain constant through the year for the
purposes of comparison in this preliminary investigation.
Calculated flood discharges at eight representative
locations are summarized in Table 6.4. Also shown are
results of a flood frequency analysis of the Chakachatna
River gage data. It is apparent that the regional flood
frequency analysis yields larger flood magnitudes than
the gage values, especially at greater recurrence
1
intervals. This may be in part due to the lack of
inclusion ~f the lake parameter in the equation for
parameter D, representing the standard deviation of the
floods~ Calculated values at locations 1 through 5 and 8
are affected by this discrepancy. Locations 6 and 7 are
likely to be better represented by the calculated values
since there are no significant lakes in their basins:
these locations are most significant in the evaluation of
the alternatives. Thus the discrepancy at the other
sites was not resolved for this preliminary investigation.
The results of the low flow investigation are summarized
in Table 6.5. Low flows were not calculated downstream
from the Chakachatna River-Noautka Slough divergence due
to lack of confidence in predicting the flow dist~ibution
at low flows. Low flows on the McArthur River should not
be reduced by the project and thus were not calculated.
The lake elevation survey resulted in an elevation of
1142 feet.
6-17
0)
1
1-'
co su
f
Table 6.2. Locations, date, and results of field discharge measurements during September
1981
Studya Loc. b Description Date Discharge
Are a
D 2 Chakachatna R. U/S of Straight Ck. 21 Sept. 5,813
D -Straight Ck. U/S of Chakachatna R. 21 Sept. 471
E -Chakachatna R. D/S of Noaukta Sl. Div. 22 Sept. 681
E -Noaukta Sl. D/S of Chakachatna R. Div 22 Sept. 1,285c
F -Chakachatna R. D/S of Middle R. Div. 26 Sept. 428
F -·Middle R. D/S of Chakachatna R. Div 26 Sept. 80
G 4 Chakachatna R. U/S of McArthur R. 26 Sept. 475
H 5 Middle R. U/S of Mouth 26 Sept. 132
I -Upper McArthur R. ~/S of Powerhouse 26 Sept. 155
J -Upper McArthur R. nr. Powerhouse 24 Sept. 93c
K -Upper McArthur R. D/S of Powerhouse 26 Sept. 297
L 6 Upper McArthur R. 24 Sept. 417
L -Upper Blockade Glacier Channel 24 Sept. 312
M -McArthur R. U/S of Lower Bl. Gl. Chan. 25 Sept. 696
M -Lower Blockade Glacier Channel 25 Sept. 514
N -Upper Clearwater Tributary 25 Sept. 87
astudy areas are illustrated on Figure 6.2
bLoc. is the corresponding representative location at which flow regimes have been calcu-
lated
cPartial measurement
(.
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1
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tr
1 f ( ~ 1 ( r f l r f r
Table 6.3. Estimated natural mean monthly and mean annual flows at eight representative locations.a
MONTH
JAN
FEB
MAR
APR
MAY
JUNE
JULY
AUG
SEP
OCT
NOV
DEC
MEAN
ANNUAL
--
Bb
(cfs/mi 2 )
0.45
0.39
0.37
0.53
2.0
7.0
11.0
9.6
4.5
1.5
0.77
0.52
--
cc
(cfs/mi 2 )
0.78
0.63
0.53
1.1
8.2
8.8
2.6
1.7
4.3
2.8
1.6
1.2
--
asee Figure 6.2 for locations
Qmld
(cfs)
613
505
445
441
1,042
5,875
11,950
12,000
6,042
2,468
1,206
813
3,645
Qm2
(cfs)
670
550
490
520
1,530
6,630
12,600
12,540
6,460
2,670
1,320
890
3,935
Qm3
(cfs)
720
590
520
580
1,930
7,220
13,070
12,930
6,790
2,830
1,410
960
4,160
Qm4
(cfs)
69
57
50
61
250
700
1,130
1,100
620
270
140
93
382
Qm5
(cfs)
34
28
24
43
270
370
290
260
230
130
69
49
150
Qm6
(cfs)
24
21
20
29
llO
380
590
520
240
83
42
28
175
bB = mean monthly flow per square mile based on calculated Chakachamna Lake inflows
Qm7
(cfs)
170
150
140
200
750
2,620
4,100
3,600
1,690
570
290
190
1,215
Qm8
(cfs)
830
690
620
740
2,580
9,250
15,970
15,330
7,870
3,160
1,580
1,070
5,011
cc = mean monthly flow per square mile based on a 4 year(l976-1979) average of mean monthly flows
of the Chuitna River (Station 15294450); mean annual flow not used
dQmi = Estimated natural mean monthly flow at location i
t
Table 6.4. Natural flood flows at eight representative locations based on a regional flood frequency analysis developed by Lamke (1979).
Ab Std Tf Q1.25
h
Q2 Q5 Q10 Q25 Q5o QlOO a pc Fe Mg Dg Location (mi 2 ) (in) (%+1) ('ro+l) {Fo) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
li 1120 ------13,527 15,848 19,051 21,202 23,962 26,055 28,183
1120 75 4 17 0 20,540.2 1.46 14,570 19,289 25,725 30,556 35,391 40,845 47,198
en 2 1216 75 3.7 17 +1 22,542.4 1.44 16,156 21,150 27,889 32,924 37,914 43,509 50,012
1 3 1289 75 3,5 18.4 +1 23,799.9 1.44 17,042 22,302 29,426 34,759 40,083 45,996 52,871 1-'
1.0 4 119 72 2.8 21.5 +2 2,453.2 1.7 1,580 2,387 3,563 4,475 5,370 6,606 8,091
5 50 55 1.4 16.5 +2 1,042 1.81 645 1,029 1,609 2,067 2,518 3,180 3,988
6 54 80 1 8.4 +2 .1,758.8 1.8 1,084 1, 716 2,686 3,461 4,260 5,364 6, 715
7 375 71 1 11.8 +3 10,219.4 1.56 6,926 9,696 13,615 16,609 19,651 23,312 27,628
8 1551 75 2.9 16.6' +2 29,862 1.41 21,650 27,882 36,269 42,533 48,791 55,554 63,401
aSee Figure 6.2 for location
bA~drainage area; values for locations 4,5, and 8 are weighted average
cP~mean annual precipitation; values for locations 4,5, and 8 are weighted averages
dst~percentage of basin containing lakes; values for locations 4,5, and 8 are weighted averages
eF~percentage of basin covered by forest; values for locations 4,5, and 8 are weighted averages
fT=mean minimum January temperature; values for locations 4,5, and 8 are weighted averages
gM and D are parameters calculated from the basin parameters; they are used in the flood frequency equations developed by Lamke (1979)
hQi~flood discharge with recurrence interval i
i These data are from a flood frequency analysis of gage data (Station 15294500)
( t 1. ( •
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Surveys to establish the water level in selected wetlands
in relation to the river water level indicated that the
wetland levels were greater than the river levels in bath
cases. A wetland on the northwest side of Noaukta Slough
downstream from its divergence from Chakachatna River was
found on 22 September to be 1.7 ft. above the water level
1
in the closest channel of the Slough. This difference is
not surprising since (1) the wetland is on the upslope
side of the river and (2) the river was dropping rapidly
from its higher summer stage. The survey was not
sufficient to establish whether or not the Chakachatna
River supplies water to the wetland.
A similar, but more approximate, survey was conducted on
the Middle River near its mouth. Wetlands are present on
bath sides of the river at a level about 6 ft. above the
Middle River water level on 26 September at about 1100
hours. Wetlands were also present on the sloping bank of
the river to nearly the river level at the time of the
survey. High water evidence was present at about 4 to 5
·feet above the surveyed river 1evel. This reach of
Middle River is within the range of tidal influence, but ,
the amount of influence was not evaluated during this
reconnaissance study. Although the data are not
conclusive, it would appear that ~he wetlands may be
flooded periodically by a combined river flow and high
tide •
The wetlands are likely to be slow-draining and may get
most of their water from snowmelt and rainfall. Data
from this reconnaissance study are insufficient to
establish with any certainty the water budget of these
wetlands.
6-20
Table 6.5 Results of law flow investigations for three locations along Chakachatna River for
each of two 6 month periods.
November-April May-October
Law Gagea Location b Gagea Locationb
Flow Data 1 2 3 Data 1 2 3
Parame ter (cfs/mi 2 ) (cfs) (cfs) (cfs) (cfs/mi 2 } (cfs) (cfs) (cfs)
7Q 0.43 480 520 550 0.62 689 750 790
7Ql. 25 0.36 403 440 460 0.43 486 530 560
7Q2 0.29 329 360 380 0.33 365 400 420 5 0.26 292 320 340 0.29 321 350 370 7 Ql0 7 Q20 0.23 263 290 300 0.26 293 320 340
7 Q50 0.21 231 250 270 0.24 267 290 310
0'\ 7 Ql00 0.19 212 230 240 0.23 252 270 290 1
N
l-' 30Q 0. 4 3 482 520 550 1.08 1,207 1,310 1,390
30Q1.25 0.37 411 450 470 0.77 863 940 990
30Q2 0.30 340 370 390 0.55 613 670 710 5 0.27 303 330 350 0.46 512 560 590 30Ql0
30Q20 0.24 273 300 310 0.39 440 480 510
30Q50 0.22 242 263 280 0.33 371 400 430
30 Q100 0.20 221 240 250 0.29 330 360 380
aLow flow frequency analyses of data from Chakachatna River gage (station 15294500)
bLocations are identified in Figure 6.2; location 1 corresponds to Chakachatna River gage site
[ t,
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4.2.3.2
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Hydraulics
Plots of stream and floodplain transects in study areas
D, L, and P (Figure 6.2) are presented on Figures 6 .. 3,
6.4, and 6.5, respectively. Stages corresponding to the
highest and lowest mean monthly flow values are shown on
the figures to show the typical annual range in stages.
The hydraulic geometry for the same three transects is
shown on Figures 6.6, 6.7, and 6.8. Mean monthly flows
are denoted on these figures. The flows increase due to
snowmelt in May, followed by a gradual increase as the
mountain snowpack continues to melt and the glaciers
begin to melt. In late summer, the flows taper off
gradually toward the winter low flows. As the discharges
change, so does the hydraulic geometry.
The Cha~achatna River exhibits a large range of stages
(Figure 6.3). Winter flows would likely be only a foot
or two deep in the main channel with very little or no
flow in the left channel. Summer flows would inundate the
bar separating the two channels and a portion of the
Straight Creek floodplain as well.
The Upper McArthur River is likely to have a relatively
sm'a.ll range of stages {Figure 6 4) • Winter flows would be
about a half foot deep and summer flows may be 2 to 3
feet more than that. Downstream, the McArthur River will
increase in both depth and range of depth (Figure 6.5).
Winter depths may be a foot or more; summer flows in the
m~in channel may be as much as 8 feet in maximum depth
with water flowing in high water channels.
6-22
6.2.3.4
Flood stages were estimated for the 10 year recurrence
interval flood at the three transects discussed above and
were plotted on Figures 6.3, 6.4, and 6 5. The
Chakachatna would likely flood the lower floodplain of
Straight Creek but will probably not flood any vegetated
areas. The floods on the McArthur remained in the
unvegetated portion of the floodplain at these transectsr
it is likely that rouch of the McArthur River would have
similar flooding characteristics.
It was apparent at sorne confluences that backwater
conditions have been experienced in one or both of the
joining channels. The backwater profile could be traced
by high water marks along the banks of McArthur River
upstream of its confluence with the Lower Blockade
Glacier Channel. Similar conditions likely occur at most
conflue~ces where the two joining channels have
dissimilar flow regimes.
Typical examples of Chakachamna Lake bottom profiles are
shown in Figures 6.9 and 6.10. Also shown on Figure 6.10
is a river survey leading into the bottom profiles. The
profile show that the bottom gradually gets deeper in the
offshore direction until a depth of approximately 20 feet
is reached, at which time the depth increase very rapidly.
Channel Configuration and Process
The channel configuration of the Chakachatna, McArthur,
and Middle Rivers and Noaukta Slough were assessed during
the field and office investigations and are identified on
Figure 6.2. The boundaries of the reaches are
approximate. Four stream configurations were selected to
represent the streams in the study area:
6-23
......
1 -
,_
·,_,/
~
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-
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-
.....,
-
-
-
·-
·----------~ ~~~
(1) Mountainous (Mt) -characterized by numerous, almost
continuous rapidsr they are usually single channeled
and are often controlled in shape and location by
external forces such as glacial moraines, rock
outcrops, and tributary deltas.
(2) Braided (B) -characterized by numerous channels,
often having different water levels~ short rapids,
often located at the divergence of two channels; and
wide, usually unvegetated floodplains: channels
'
tend to shift their location and configuration
frequently in response to the deposition of sediment
transported in from .upstream.
(3) Split {S) -characterized by one to three relatively
stable channels, often having different water
t levels, all of which carry water for much of the
year.
(4) Meandering (M) -characterized by a single channel
whose thalweg (deepest part) shifts from one side to
the other along the length of the stream; large sand
or gravel bars are typically exposed on alternating
sides of the stream at low flows •
Stream reaches in the study area with mountainous
configurations include the upper reaches of the
Chakachatna River in Chakachatna Canyon which has almost
continuous rapids and maintains mostly a single channel.
The ice cored moraine of Barrier Glacier controls the
upper reach; old rnorainal and colluvial deposits form the
control of the lower reach. The McArthur River also has
two rnountainous configuration reaches. The upper reach
6-24
is well into the headwaters of the river; control is
provided by cobbles and boulders whose source is the
surrounding and upvalley mountains. The lower reach is
formed by the terminal moraine of Blockade Glacier. The
mountainous reaches on the McArthur River are primarily
single channel reaches.
Braided configuration reaches in the study area include
the Chakachatna River upstream of Straight Creek, Noaukta
Slough, and the Upper McArthur River. The Chakachatna
River reach is very typical of a braided configuration;
numerous channels flow at different water levels, the
number of channels being a function of the discharge
entering the reach. The Noaukta Slough configuration
appears to be due more to lack of channel capacity than
to excessive deposition of sediments. However, dune
bedforms extended across most of the channel width in
many locations indicate that heavy bedloads are
transported at and.above sorne threshhold discharge. The
braided reach on the Upper McArthur River is a result of
sediment deposition. It contains numerous small channels
flowing at different water levels.
There are two split configuration reaches in the study
area. They are located upstream and downstream of the
Chakachatna River braided reach. The upper reach appears
to be steeper, contains more rapids, and is likely to be
less stable than the lower reach. Both reaches are
nearby a braided configuration, but they appear to be
much more stable than the typical braided reach.
Meandering configurations are typical of the lower
reaches of the Chakachatna River and most of the McArthur
and Middle Rivers. The lower Chakachatna and Middle
6-25
-
--
"'-
,,_,.
,_
'""""'
-
-
.....
,_
,..._
-
"-
,_
'-
River reaches are very similar in appearance; both are
primarily single channel with few exposed bars, even at
relatively low flows. 'Dune bedforms were numerous and
closely spaced over the full length of these reaches.
The McArthur River has two channels downstream of
Blockade Glacier. The north channel receives inflow from
the glacier via two main channels. The north and south
channels both flow mainly in a single channel meandering
configuration before joining near their confluence with
Noaukta Slough. The channels appear to be the most
active of all channels in the study area in terms of
lateral migration, from which many logs have been
introduced into the floodplain. Very large sand and
gravel bars are evident at low flow conditions. Large
dunes in the channel provided evidence of a significant
bedload transport above sorne threshhold discharge •
Sedimentation characteristics in the study area include:
o sediment transport characteristics and
o bed and bank material types.
\
Sediment transport was discussed briefly above in terms
of bedforms providing evidence of bedload movement. The
Chakachatna River downstream of the canyon and upstream
of the Noaukta Slough divergence contained sorne gravel
dunes as the most evident bedform; these dunes are often
found at the head of a channel where it splits from
another channel. All channels downstream from the
Noaukta Slough divergence and all of the McArthur River
downstream of Blockade Glacier had dunes formed mainly of
sand sized particles.
6-26
6.2.4
Suspended load contains concentrations of fine "glacial
flour". Sand sized particles will likely be carried in
suspension by discharges greater than those at the time
of the reconnaissance.
Bed and bank materials are typically gravels, cobbles,
and sorne boulders in the Chakachatna River from the lake
to the Noaukta Slough divergence and in the Upper
McArthur River down to Blockade Glacier. There are sorne
sandy sections in the braided reach of the Upper McArthur
River as well. The size distribution of the bed and
banks then decreases rapidly in the downstream direction
to become very fine sands and silts near the mouths of
the rivers.
The ice characteristics in the study area have not been
investigated. It is likely that the rivers develop a
full ice caver over their entire length. It is possible
that aufeis develops locally within each of the braided
reaches; the most likely reach for this to occur is the
braided reach of a continued good source of water and the
shallow channels in the reach. However, there is no
strong evidence for aufeis development in these reaches~
Conclusions
The 1981 field reconnaissance and subsequent office
evaluations have provided valuable information regarding
the characteristics of the two river systems that could
be impacted by the proposed Chakachamna Hydroelectric
Project. Additional information will be collected on the
Chakachatna and McArthur River systems prior to assessing
the final impact of the project.
6-27
'lllilii
-
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-
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-
-
,_
-
'-
',_-;
·-
-
-
-
-
~-----------~-~--~~~--
The 1981 field reconnaissance provided the following
types of information:
o instantaneous discharges at various locations
throughout the study area that provide information on
flow distribution, hydraulic roughness, and channel
bottom configuration,
0 lake water level for comparison with historie water
levels,
o wetland water levels relative to adjacent streams for
evaluating wetland water sources,
o stream and floodplain transects for evaluating local
water levels for a variety of discharges,
• o stream water surface gradients for estimating energy
gradients for hydraulic calculations,
o lake bottom profiles for evaluating the lake tributary
stream gradients following draw down of the lake l_evel,
o observations of channel configuration and processes
for evaluation of the changes that could occur ta the
various configurations under a regulated flow
condition, and
o observations of bed and bank materials for evaluating
the sedimentation characteristics of the stream
systems.
6-28
Although these reconnaissance level field data were not
always rigorously collected nor extensive in areal
coverage, they provide a valuable starting point for
making preliminary impact evaluations and for planning
more detailed field and office investigations.
The office evaluations of the field data provided the
following results:
o Hydrologie data developed for eight representative
locations through the study area were typical of
glacial rivers with low flow in late winter, large
glacier melt flows in July and August, and annual
peaks due to fall rains; the data include:
-mean annual flows,
-mean monthly flows,
-flood flows with various recurrence intervals, and
- 7 and 30 day low flows with various recurrence
intervals.
o Hydraulic geometry calculated at three representative
transects illustrates that the range of width, depth,
and velocity for the natural flow regime is typical of
streams of this size; the annual range of stages
appears to increase in the downstream direction.
o Floods on the McArthur River are likely to remain in
the unvegetated floodplain for all but the most
infrequent events, although most floods will likely
result in substantial bank erosion; floods on the
Chakachatna also will likely remain mostly in the
unvegetated portion of the floodplain.
6-29
-
-
,_
-
-
-
. ....,
-
l,_.
-
-
--
--
\,.._
-
'-
,.._
-
--
-------------~4----=~
o Backwater conditions at stream confluences are a
likely condition.
0 Chakachamna Lake bathymetry indicates that a distinct
break in bottom gradient occurs at a depth of
approximately 20 ft at the deltas of major tributary
streams; at shallower depths, the gradient is gradual
and at deeper depths, the gradient is steep.
o Chakachatna River contains reaches with the following
configurations:
-mountainous in Chakachatna Canyon,
braided downstream of canyon and in Noaukta Slough,
-split in the lower part of the canyon and between
the bridge and Noaukta Slough, and
-meandering in downstream reaches.
o McArthur River contains reaches with the following
configurations:
-mountainous in the headwaters and at the Blockade
Glacier moraine,
-braided on the Upper McArthur between the two
mountainous reaches,
-meandering through the entire lower McArthur River.
o Sedimentation characteristics of both rivers appear to
be typical of glacial systems with very fine suspended
sediment sizes and substantial bed load transport.
6-30
6.3
6.3.1
o Ice characteristics are assumed to include development
of a full ice cover and have minimal aufeis
development.
The above results were based on field data, office
evaluations, professional experience, and several
important assumptions. The assumptions must be checked
during the 1982 investigations.
Aquatic Biology
Background
To perform a reconnaissance level evaluation of the
Chakachamna Hydroelectric Project study area resources,
it was necessaty first to review the literature,
particularly reports of previous studies. A variety of
regulatory agencies were contacted including the u.s.
Fish and Wildlife Service (USFWS) and the Alaska
Department of Fish and Game {ADF&G) • The ADF&G, Division
·of Sport Fish, has conducted a number of surveys in
portions of the Chakachamna Lake -Chakachatna Rivee and
1
McArthur River systems over the past 30 years. These
surveys have included aerial observations, gill netting,
electroshocking, and ground obser7ations.
In general, these reconnaissance level surveys were
primarily aimed at detecting spawning runs of salmon.
However, these efforts were often hampered by turbid
glacial waters. As a result, sorne salmon species were
often unobserved.
6-31
lloiii
~
-
6.3.1.1 -
-
-
-
-
-
-
-
-
'tk_~
6.3.2
"""'
"""'
-
-
Overall, these studies showed that all of the Pacifie
salmon species were present in the general vicinity of
the project area (Table 6.6). However, the presence of
these species was not documented at more than a few
locations nor had the habitat utilization been documented.
Study Area
The study area has been generally described in previous
sections. Refer to Section 6.0 and 6.1 for more detail.
The Chakachamna -Chakachatna and Chilligan River System
and the McArthur River System are large complex water-
bodies. The riverine systems contain braided reaches,
islands, inactive floodplains, sloughs, riffles, white-
water areas, side channels, tributary streams, inputs of
groundwater flow, and boulder strewn areas of high
gradient. The main stems of these rivers contain
glacially turbid waters, although there are also clear
water tributaries present in each system.
Habitat diversity is further enhanced through substrate
and water quality variability. Substrates typically
range from silt and fine mud to large boulders. Water
temperatures during the fall season can vary by more than
l0°C, ranging from 0.25°C glacial runoff to ll°C shallow
pools. Water depths also vary, with sorne areas of the
Noaukta Slough being less than 0.5 ft. deep, while sorne
areas in Chakachamna Lake are more than 300 ft. deep.
Study Objectives and Methodologies
Two reconnaissance level surveys were conducted on
Chakachamna Lake, and the Chakachatna, Chilligan and
~
McArthur Rivers during 1981. The investigations included
6-32
0"1
1
w
w
l_
Table 6.6 Surveys conducted by and for Alaska Department of Fish and Game. (By date, location,
method and species found)
Salnon Species other Species
Location and Date M3thoda Sockeye Chinook Coho Chum Pink
D::>l1y Ra.:i..Iû::JOW---take--Pomd Slimy
Varden Trout Trout Whitefish Sculpin
Chakachamna_Lake
9/52 Vis
9/53 Vis * ...
9/54 ES, Vis
9/56 ES +
1979 GN, ES + + + + +
Chi11igan River
9/52 ES, Vis" +
9/53 Vis *
8/54 ES, Vis +
8/55 ES, Vis +
Igitna River
8/52 Vis +
9/52 Vis
9/53 Vis *
Another River
8/52 Vis *
Kenibuna Lake
8/52 Vis +
9/53 Vis *
Chakachatna River
7/52 Vis *, **
6/58
1961 Vis, GN + +
l
0'\
1
w
of,::.
f f l { (
Table 6.6. Concluded.
Salnon Species
IDeation and Date M=thoda Sockeye Chinook Coho
Straight Creek
1958 Vis
1973 *** Vis +
1976 *** Vis +
1977 *** Vis +
1978 *** Vis +
1981 *** Vis +.
McArthur River (in-
cluding Swank Slough
and Flat Lake)
1959 Vis
7/61 + +
8/61 +
9/61 +
West Creek
7/61 GN, Vis + +
9/61 GN, Vis
#8 Creek
7/61 GN, Vis +
North Fork
7/61 Vis, GN +
aGN-Gi11 net; Vis-Visua1; ES-E1ectroshocking
* Too muddy to observe fish
** Two beluga whales at mouth
*** Chinook salmon survey only
r ( { l [ f [ {
Other Species
Iblly Rainbow Lake Found Slirqy
Chum Pink V arden Trout Trout Whitefish Seul pin
+
+
+
+ + + +
+ +
+ + +
+
many of the tributary streams as well. The first recon-
naissance, that was conducted on 17-18 August, consisted
of aerial observations of the project area. The object-
ives of this reconnaissance were to assess:
o the extent of the system,
o which areas should be sampled in view of their
potential to be impacted by the proposed project,
o what types of sampling gear might be used; and
o the potential logistical problems caused by the site
location and topography.
The second reconnaissance, conducted from 15-28
September, involved the collection of data from the areas
identifi~d during the initial reconnaissance. This
effort employed both field sampling and visual obser-
vations. The objectives of this reconnaissance were to:
o identify the major species present during autumn;
o identify critical habitats and life functions taking
place in the system at the time of the study;
o provide an insight to the species composition and
habitat use occurring at different times of the year;
o evaluate those species and habitats potentially
vulnerable to impacts that might occur during the
construction and operation of one of the proposed
alternative hydroelectric facilities; and
6-35
-
ÏIIIIIÎ
'-'
,_
.....
-
-
._
,_
,_,
-
-
"-
-
·=-
-
-
6.3.2.1
6.3.2.2
o evaluate the nature and extent of studies that would
be necessary to assess the minimum amount of water
necessary to maintain a viable salmon fishery. Due to
the reconnaissance level nature of the 1981 effort, it
was decided that only the fish populations in these
systems would be investigated. Invertebrate work
would be conducted in 1982.
August Reconnaissance
The first reconnaissance primarily relied upon visual
observations, including both aerial overflights and
ground-level reconnaissance. During aerial overflights,
the location of spawning salmonids were observed and
recorded. At selected sites, ground surveys were
conducted. At these locations, carcasses were observed
and identified and photographs were taken to document
observations of habitat parameters. The results of this
reconnaissance were used in planning the 1981 fall survey.
September Reconnaissance
Since the September reconnaissance included the sampling
of a variety of habitats at various depths and under
varying flow conditions, a number of different fish
collecting techniques were used. Table 6.7 lists the
fish collection methodologies used in each water body,
while specifie gear types are identified in Table 6.8.
Visual observations of all major water bodies were
recorded from a helicopter at altitudes between 10 and
200 ft.
6-36
Electroshocking, using backpack electroshockers, was
utilized in most areas where water depths of four feet or
less were encountered and conductivities were less than
2000 micromhos/cm. The electroshocker immobilizes fish
enabling them to be collected. Pulsed direct current
(DC} was utilized to reduce the physical damage to fish
while it allowed taking advantage of galvanotaxis (the
attraction of fish to the anode electrode), thus making
them easier to catch with a dipnet. The relatively small
range of the backpack shocker confined its use to shore-
line areas and shallow open water areas. It was
generally operated by one member of the field team while
one or both of the other members deployed dipnets or
seines. This technique was particularly effective in
collecting juvenile fish that were sheltered among rocks
and snags and could not be sampled with other equipment.
It was also useful in fast flowing areas when used in
conjunction with a seine or stationary drift net since
fish could be collected from swift moving waters that
would otherwise be inaccessible. Areas sampléd by
electroshocking, seine netting or both are shown in
Figure 6.11.
A hand seine {Table 6.8} was utilized both individually
and in conjunction with the electroshock~r. When used in
conjunction with the electro shocker, the hand seine was
deployed downstream, usually in swift currents. In slower
moving water the seine was moved upstream (with the ends
of the seine extended) toward one member of the field
team who kicked or shuffled the substrate. This gear was
effective on both small and large fish in confined
channel reaches and along shorelines.
6-37
-
..
-
_..
-
"' 1
w
00
{ r 1 { r ( I { r { ( l { ( ( {
Table 6.7. Collection methodologies utilized by waterbody, September 1981 reconnaissance study
Visual Electro-Hand Beach Gill Fyke Stationary Hoop Minnow
Water Body Observations shocking Seine Seine Drift Nets Nets Nets Nets Traps
(Trawl)
Igitna River x
Kenibuna Lake x
Another River x .
Chilligan River x
Neacola River x
Chakachamna Lake x x x x x x x
Shamrock Lake x
Nagishlamina River x x x ~ x x
Chakachatna River x x x x
Straight Creek x x x x
Straight Creek Tributary x x x
Middle River x x x x
Noaukta Sough x x x x
McArthur River x x x x
McArthur River Tributary x x x
Chuitkilnachna Creek x
--------~----------------------------------·---------~--··-
aAt mouth of river in Lake Chakachamna
Table 6.8. Collection gear specifications September 1981 re-
connaissance study.
Electroshockers
Coeffelt Model BP-2 -used at 600 v
Smith-Root Model VII -700 v at 6 millisecond pulse
duration at 60 pulses/second
Hand Seine
10 ft x 6 ft -~" ace mesh
Beach Seine
lOO ft x 6 ft -~" ace mesh
Gill Nets • 75 ft long, each panel 15' long x 6 ft deep
Panels of nylon monofilament 3/4 11 , l", 1.5", 2", 2.5••
bar mesh
Fyke Nets
6 1 x 4 1 double funnel ~·· square mesh
Long wings and leads 300 ft -1" square mesh
Short wings 50 ft -l" square mesh
Hoop Nets
No leads -Small 34" diameter l" stretch mesh
Large 48" diameter 1-~" stretch mesh
6-39
--
-
'--
-
-
-
-
'-
,_
-
-
,_
-
-
~~~~~,~~~------------~
The stationary drift net used in this study was an otter
trawl with a fine mesh liner. It was deployed in streams
with high velocity currents. The streamlined shape of
this net allowed it to be deployed in areas where the
water currents were too swift to deploy a seine.
The beach seine was similar to the hand seine described
above but of much greater length (Table 6.8). This net
was only used in Chakachamna ;Lake. One end of the net
was secured to the shore while the other end was carried
out from shore by boat. As the boat moved in an arc back
to shore, the bottom of the net was kept on the lake
bottom, thereby surrounding a volume of water. This
technique was effective, but only in those areas where
the current was relatively small or nonexistent and where
the shore area was shallow enough to deploy the net
properly.
Experimental, 75 foot long gill nets (Ta~le 6.8),
consisting of 5 panels of 0.75, 1, 1.5, 2, and 2.5 inch
bar mesh were utilized only in Chakachamna Lake. These
nets were deployed perpendicular to the shore, and at the
surface and bottom (Figure 6.12). The small mesh panel
(0.75") was always kept on the shoreward side, where
juvenile fish concentrate their activity. The nets were
marked with floats and checked after 1 to 3 hours. All
fish collected were measured and weighed and live fish
were released. Those nets that did not catch large
numbers of fish were left in place overnight.
The gill nets facilitated the collection of fish in
deeper areas of the lake. By leaving the nets set
overnight a more time-integrated sampling of the fish
populations was possible.
6-40
Fyke nets (Table 6.8) are trap nets that are set with
long leads of heavy twined mesh. Fish that encounter the
leads are guided towards a series of mesh funnels that
guide the fish into a trap from which they can be
removed. The leads and net are held in place and
oriented by steel poles driven into the bottom. The nets
can be used where water is shallow enough (generally 4
feet) to allow the leads to extend from the stream bottom
to the water surface, and where water currents are at a
minimum.
Advantages of the fyke net include both the large areas
fished and the fact that they do relatively little damage
to trapped fish. These nets were set in the deep water
sections of the rivers that could not be adequately
sampled by other gear (Table 6.7). In the Noaukta
Slough, Middle River, and Chakachatna River the wings of
the nets essentially directed all fish moving upstream
into the funnels. In the McArthur River one main-channel
section was completely blocked by the nets.
Hoop nets were set without leads in Chakachamna Lake at
each of the gillnetting sites (Table 6.8). This was done
to diversify the fishing techniques utilized so that
species or individuals not vulnerable to the gill nets
might also be collected. This gear was relatively
ineffective.
Minnow traps, made of galvanized mesh were set near the
hoop nets. These traps had much smaller mesh than either
the gill nets or hoop nets and were utilized to again
diversify the gear and enable the collection of smaller
fish such as juvenile salmonids. These were generally
6-41
-
~
'-
-·
-
'-'
~-
-
1-
li'~
"""
set among rocKs or other such cover that usually provides
habitat for juvenile fish.
The variety of collecting gear used prevented biasing of
our collections through gear selectivity. In this
manner, fish of many different life stages and in
different habitats were_successfully collected thus
providing a more complete picture of the fish populations
present at each site.
In the field, fish were measured for total length and
usually weighed to the nearest ounce. Where possible,
the sex of the fish was noted and whether the fish, in
the case of salmonids, was a parr, smolt, juvenile or
adult. Scales were taken from selected specimens. All
captured adult salmon and other live fish were released
at the point of collection.
Juveniles were identified in the field and released
whenever possible. Specimens whose species identifi-
cation could not be confirmed in the field and voucher
specimens were preserved in a 10 percent formalin
solution for laboratory identification.
Physical data collected in the field consisted of water
temperatures measured with a YSI Model 57 temperature-
oxygen meter or a Taylor mercury thermometer, and water
velocities measured with a Marsh-McBirney Model 201
electromagnetic flow meter or a General Oceanics Model
2035B remotereading flow meter.
6-42
6.3.3
6.3.3.1
Fish specimens were identified in the laboratory using
keys prepared by Hart (1975) , McConnel and Snyder (1972) ,
Morrow (1980) Scoott and Crossman (1973), Smoker (1955),
Troutman (1973) and Wydoski and Whitney (1979). Habitat
requirements of salmon and trout were characterized by
Bailey (1969) , Balon (1980) , Blackett (1968) , Foester
(1968), Martin and Oliver (1980), Merrell (1970), Morrow
{1980) , Nikolskii (1961), and Scott and Crossman (1973).
Results and Discussion
Although a large amount of data were gathered during the
two 1981 reconnaissance efforts, these data represent
only the biological events occurring within the short
period of time encompassed by these investigations. The
occurrence and extent of biological activities during the
winter, spring, and early summer, can only be
hypothesized. Data that were collected include:
o Species occurrence;
o Habitat utilization;
o Critical life functions taking place; and
o Relative success of the collection gear.
The following sections summarize the results of these
data.
Species Occurrence
Species occurre~ce is perhaps one of the most significant
results of this reconnaissance. All five species of
salmon occurring in Alaskan waters were found to spawn in
both drainages (Table 6.9). It is unclear at this time
6-43
-
~
0"1
1
""' ""'
{ I r r 1 ( f { f r f
Table 6.9. Species list and drainage of occurrence August-September 1981.
Species
pygmy whitefish
round whitefish
Dolly Varden
lake trout
rainbow trout
pink salmon
chum salmon
coho salmon
sockeye salmon
chinook salmon
arctic grayling
slimy sculpin
threespine stickleback
ninespine stickleback
Prosopium coulteri
Prosopium cylindraceum
Salvelinus malma
Salvelinus namaycush
Salmo gairdneri
Oncorhynchus gorbuscha
Oncorhynchus kèta
Oncorhynchus kisutch
Oncorhynchus nerka
Oncorhynchus tshawytscha
Thymallus arcticus
Cottus cognatus
Gasterosteus aculeatus
Pungitius pungitius
1 rncludes Lake Chakachamna and Middle River
Drainage of Occurrence
Chakachatna McArthur
Riverl River
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
[
which species usually is most abundant, but spawning
sockeye salmon were most abundant during our investi-
gation. Lake trout appeared to occur only in Chakachamna
Lake, while Dolly Varden were ubiquitous throughout both
drainages. Rainbow trout appeared only in the lower
portions of both drainages. Round and pygmy whitefish
were found in most areas of both drainages, although
pygmy whitefish were not foun~ in Chakachamna Lake or
drainages above it. Slimy sculpin were found throughout
both systems and in tributary streams. Sticklebacks,
however, were only found in backwater areas and among
vegetation, usually in the lower reaches of the rivers.
Only a single grayling was observed in a side channel in
the upper Nagishlamina River and none were collected or
observed at any other location. It is clear, with few
exceptions, that most of the species found, occurred
throughout both drainages • •
The fish in this area may be classified into two primary
groups, forage fish and commercial and sport fish.
Forage fish in the project area include threespine
stickleback, ninespine stickleback, slimy sculpin, pygmy
whitefish, and round whitefish. (Morrow 1980, Scott and
Crossmen 1973, Balon 1980). Although the round whitefish
is probably not used as a subsistence species in these
drainages it is eaten by lake trout and other species of
fish. Sport and commercial fishes include pink, chum,
sockeye, coho and chinook salmon, Dolly Varden, lake
trout, rainbow trout, and grayling (Morrow 1980, Scott
and Crossman 1973).
6-45
-
-
-
-
-
,_
-
-
'"""
;.,...,
,_
-
._
-
6.3.3.2 Habitats Utilized For Various Life Functions
A wide variety of habitats were sampled during the course
of the reconnaissance studies using a diverse assemblage
of sampling gear. As stated, one objective of the 1981
program was to gather a wide variety of data from a large
area during a relatively short period of time, thus more
attention was given to collecting qualitative rather than
quantitative data, and to characterize general habitat
use. Habitat utilization will be reported and discussed
by waterbody or river stretch, as appropriate.
Chakachamna Lake Tributaries
The results of studies at each site sampled or observed
in the Chakachamna Lake/ Chakachatna River drainage is
summarized in Figure 6.13. This figure identifies
habitat utilization and potential habitat utilization for
salmon and trout species.
The rivers flowing into Kenibuna Lake were investigated
by means of low level overflights, since the waters in
the Neacola, Another and Igitna Rivers were sufficiently
clear to observe fish and generally characterize the
substrate. The Neacola River, at the date of the
overflight, was relatively shallow with an apparent sand/
silt substrate. Large amounts of emergent vegetation
were present, and although the substrate appeared to be
unsuitable for salmon spawning, several adult Dolly
Varden were seen from the air. It is possible that round
whitefish were also present and that sockeye salmon
juveniles may utilize this river •
6-46
The Another River was also overflown at relatively low
altitudes in September 1981, and was found to contain a
substrate composed of gravel, cobble, rubble, and
boulders including sorne areas suitable for salmonid
spawning. Although the water was clear with riffles, no
sockeye salmon were observed, however, one adult Dolly
Varden was observed. The stream could potentially
provide habitat for adults and juveniles of stream
dwelling species, such as Arctic grayling, round
whitefish and slimy sculpin.
When the Igitna River was overflown, the water was
somewhat clouded by glacial silt. However, it was
obvious that there was a great deal of gravel substrate
and large numbers of sockeye salmon were observed and
redds (spawning nests) were identified.
The arèas of the stream that were utilized most
intensively were the side-channels and relatively shallow
areas of the main channel within a few miles of Kenibuna
Lake. Sorne of the side channels appeared clearer than
the main channel possibly due to the influence of flows
from clearwater tributaries or groundwater.
are preferred by Sockeye (Foerster, 1968).
Such streams
Within the
stream sections utilized by sockeye salmon, there
appeared to be about 3-10 fish (including both live and
dead) for each 10 feet of stream length. Sockeye
carcasses were abundant and while not counted, there were
probably more than 1000 fish in this gerteral area.
Although Kenibuna Lake was too turbid for proper
observation, a Dolly Varden was seen at the mouth of the
Igitna River. During overflights conducted by ADF&G in
1952 (undated) sockeye salmon were seen at the west end
6-47
lillili
'"-"
'-
.....
'"""
.....
,_
-
·-
'
of· the lake (Table 6.6). In addition to serving as a
migratory pathway for spawning sockeye salmon, the lake
probably also serves as nursery habitat for juvenile
sockeye salmon. The lake may also provide habitat for
lake trout and kokanee since these species were collected
from Chakachamna Lake. The potential also exists for
salmon or lake trout to spawn along the northeast
shoreline of Kenibuna Lake since a gravel-cobble
substrate is present.
The Chilligan River, which discharges into the northwest
end of Chakachamna Lake was overflown during both August
and September 1981. · Although the river waters were
cloudy, large numbers of sockeye salmon were observed
during both investigations. Gravel and cobble substrates
were common in many parts of the river. Sockeye salmon
were present in large numbers but appeared to be more
abundant in side channels of the river, particularly in
those with clearer water. (Figure 6.14.) More than one
thousand fish were observed during each 8urvey. During
the August overflight, there appeared to be sorne chum
salmon present in the lower part of the river, however a
positive identification could not be made due to the
depth and turbidity of the water. Dolly Varden may also
use the Chilligan River for spawning and were observed
near the banks, in shallow water. The combination of
substrate, water temperature, and current found in this
river meet the habitat criteria for Dolly Varden
described by Blackett (1968) and Leggett (in Balon 1980).
The Nagishlamina River, which discharges into the
northeast end of Chakachamna Lake was overflown in August
and September. Ground observations were conducted during
August and nets were used at the mouth of the river
6-48
l..,
during September. The ground reconnaissance in August
revealed both adult and juvenile Dolly Varden as well as
one Arctic grayling in the upper r~aches of the river.
Dolly Varden were also observed in the areas closer to
the lake (Figure 6.13}. A variety of sub-strates, with
large stretches of gravel and cobble that appeared
suitable for spawning by a number of salmonid species
were also found. The upper reaches of the river were
shallower and less cloudy than areas closer to
Chakachamna Lake.
A sand delta occurs at the mouth of the Nagishlamina
River. This area was fished with nets during the
September reconnaissance. Dolly Varden, lake trout
juveniles and adults, and juvenile and ripe adult sockeye
sal!non were captured. In addition, one ripe kokanee male
was collected. During the last day of the September 1981
reconnaissance several large gray fish were observed in
the river. These may have been coho salmon or kokanee or
possibly·Dolly Varden. The presence of coho above the
mainstem of the Chakachatna River will need to be
confirmed during future studies.
Chakachamna Lake.
Chakachamna Lake is large and deep. On the average, the
lake is over 300 ft. deep, with relatively steep slopes
and very narrow shallow areas (U.S. Geological Survey
bathymetrie charts 1960). Slopes of 1:2.5 or even 1:1.1
are not uncommon in sorne portions of the lake and gentler
slopes of 1:5 are only found at the river deltas. The
water in the lake is cloudy due to glacial silts. The
shoreline varies from sand deltas to gravel beaches to
boulder slopes. Because the perimeter of the lake is
6-49
*
-
,_
-
-
-
-
-
""""'
-
-
-
-
-------·---.---~~~--~m·-----' ~ """""""''
very large, a fairly extensive shallow water habitat:
exists despite the narrowness of the shallow water zone
found along the shoreline.
During the September investigation, five species were
collected in the lake including, ripe sockeye salmon
migrating along the shore of the lake, lake trout, Dolly
varden, round whitefish, and slimy sculpin (Figure 6.13}.
Substrates suitable for sockeye salmon and lake trout
spawning were found in several areas of Chakachamna
Lake. It appeared that the sockeye were spawning along
one area of gravel beach on the north shore of the lake
(Figure 6.15). The substrate in this area was suitable
and a large number of sockeye were milling about in the
area. Although visibility prohibited observing redds, a
female was observed excavating a redd. It is unclear to
what extent this area is used for spawning, however, the
beach area was apparently utilized as nursery habitat by
juvenile sockeye salmon, lake trout, and round whitefish
(~igure 6.13). Adult lake trout, round whitefish, Dolly
Varden and slimy sculpins were also found in this area.
The round whitefish in this area were feeding on 1nsect
larvae, and the lake trout were feeding on juvenile
sockeye salmon and round whitefish.
Adult lake trout were found in all areas sampled,
although they were most abundant in rocky areas,
particularly those sites with large boulders. Many of
the adults examined during the September 1981 investi-
gation were sexually mature spawners. This may have
influenced their distribution, since the rocky shallow
water areas are used for spawning. The lake trout in
these areas were also found to be actively feeding. The
6-50
stomach contents of one large lake trout contained 22
sockeye salmon parr.
Dolly Varden did not appear to be as abundant as lake
trout, but were found at most collection sites.
Anadromous, sexually mature Dolly Varden were identified
near the lake outlet, while juvenile Dolly Varden were
present in many of the shallow water areas.
Several of the small streams entering the lake were
surveyed and were found to contain fish. One large
stream at the southern end of the lake that was fed by
glacial runoff (B in figure 6.15) contained suitable
substrate for salmonid spawning, however, the water
temperature was too cold. (0.25°C, compared to the 7.5° -
9°C found in the lake).
Although the deeper open water areas of the lake were not
sampled during this reconnaissance, information from the
literature (Scott and Crossman 1973) and past studies
(Russells 1979) indicate that these areas would normally
be utilized by lake trout and juvenile sockeye salmon.
Since the juvenile sockeye are planktivorous (Scott and
Crossman 1973) , they would be expected to make extensive
use of the open lake waters. Due to cooler temperatures
in Chakachamna Lake, lake trout would be expected to make
greater use of the upper strata all year long.
Upper Chakachatna River
Waters from Chakachamna Lake discharge from an outlet at
the eastern end of the lake (Figure 6.15) into the
Chakachatna River. This reach of river was characterized
by a steep gradient, boulders, standing waves, and white-
6-51
liooili
-
--------------------------------~--------~----------~--~~=----=-=-----=-=-=~~--~-------~-~ = A m ~ wwmw ww = ~
·-
-
-
-
-
b...,
-
-
-
water. The water remains at a relatively high gradient
to the base of the canyon about 14 miles east of the lake
(Figure 6.13 and 6.16).
Due to the relatively swift currents and lack of cover in
the upper portions of the Chakachatna River canyon, this
area apparently is used only as a migratory pathway by
the salmon and Dolly Varden that spawn in and above
Chakachamna Lake. It is also apparent that this section
is used by outmigrants, including sockeye smolt and Dolly
Varden.
During August and September, sockeye salmon and chum
salmon were observed spawning in side channels in the
lower canyon where there was a lower velocity current
than in main channels. Juvenile Dolly Varden and salmon
were also found to utilize the side channels throughout
the lower canyon. However, they were also found in the
main channel in areas where boulders provide cover and
reduced velocities.
Along the main channel of the river (Figure 6.13) Dolly
Varden, pygmy whitefish and round whitefish were found in
most areas. Dolly Varden appeared to be most abundant.
Rainbow trout were commonly found tn major channels below
Straight Creek.
Substantial numbers of sockeye, chum, and pink salmon
were found to spawn in side channels along the
Chakachatna River considerably downstream of the canyon.
The largest numbers of spawning fish were found near the
confluence of Straight Creek and downstream from the
Chakachatna bridge. Those areas containing spawning
redds generally were side channels with suitable
6-52
substrate that contained ground water flows or clearwater
tributaries (Figure 6.17). Pink salmon were found in the
vicinity of the Chakachatna River bridge during the
August survey, however, at the beginning of the September
survey, only one desiccated pink salmon carcass remained.
The extent of pink salmon spawning and the presence of
other spawning locations within the river are presently
unknown. Chinook salmon were not observed spawning in
the main channel of the river although sorne chinook were
observed in the vicinity of the confluence of side
channels with the main channel. Coho salmon were
observed migrating up the Chakachatna, but the location
of their spawning areas are presently unknown. Sorne coho
probably spawn in Straight Creek, while others may spawn
in the Nagishlamina River. It is unclear whether any
coho spawn in side channels of the Chakachatna River.
Overall, the largest numbers of spawning salmon were
found in the Chakachatna near the bridge and in Straight
Cree k.
During the September 1981 reconnaissance, the river stage
had dropped from that observed in August. During both
reconnaissance trips, there were many side channels and
backwater areas present, particularly below Straight
Creek. Typical bank habitats varied from cobble-gravel
to sandsilt. Juvenile fish were found in most areas
containing a cobble-gravel substrate, while larger fish
were generally found further from the banks in areas of
swifter current. Migrating salmon were found to utilize
the backwaters for "resting areas" during their u-pstream
migrations.
6-53
llilili
u
~
-
-
-
f
-
----~~~-----------------~---..
Straight Creek
Straight Creek, a major tributary of the Chakachatna
River, contains substrates that vary from sand-silt to
cobble-rubble, including many areas of gravel-cobble
substrates suitable for salmonid spawning. The waters
are cloudy with glacial silt and visibility is very
limited.
Water velocities in the creek vary. Velocities in the
center of the main channel have been measured at 6 ft/sec
during high flows. Side channels at the same time had
velocities of between 0.6 and 1.2 ft/sec.
Collections from the side channels and backwater areas of
the creek show that these areas are used extensively by
juvenile salmonids, of which Dolly Varden, chinook salmon
parr and pygmy whitefish are the most common. Both
chinook and coho salmon have been observed migrating up
Straight Creek. ADF&G recognizes Straight Creek as a
chinook spawning stream.
However, it is unknown whether they spawn in the
clearwater tributaries to the creek or whether sorne spawn
in the creek itself. Chum and sockeye have also been
observed migrating up Straight Creek near its mouth.
Both species areJalso believed to spawn just outside the
creek mouth, in side channels of the Chakachatna River.
Spawning sockeye, chum, pink and chinook salmon were
observed in the clearwater tributary to Straight Creek
(labelled A in Figure 6.17) during the August
reconnaissance. Migrating coho salmon, as well as
6-54
/
spawning chums and sockeyes were observed during the
September study.
The tributary is relatively narrow compared to Straight
Creek, with a main channel width of about 30 ft. The
substrate is largely gravel with sorne sand and cobble.
The banks are heavily overgrown with trees and other
vegetation. There are also cutbanks throughout the area;
roots, snags, and sweepers also provide significant cover
in this stream. The stream contains side channels and
backwaters as well as a variety of pool and riffle
habitats.
Juvenile salmonids were abundant in this stream
particularly chinook and Dolly Varden parr. The shallow
areas around snags and tree roots appeared to be favored
areas due to the lower water velocity and cover. Larger
' Dolly Varden and rainbow trout were found in deep,
swifter moving water, and were found to be consuming both
Dolly ~arden and chinook salmon parr, as well as pygmy
whitefish. Although neither rainbow trout spawning areas
nor juveniles were found in this stream, substrate and
other habitat factors necessary for spawning were present
(Morrow 1980, Scott and Crossman 1973).
Lower Chakachatna River.
The lower Chakachatna River divides up into three
principal outflows. These are the Middle River, the
Chakachatna River and the Noaukta Slough.
This lower portion of the Chakachatna River was
characterized by relatively shallow depths and slower
moving water than stretches further upstream. The
6-55
-
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-
-
._
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-
-
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--------~------~----------------~~-----------------------------------
substrate for this section of river was primarily a sand
silt mud. There were relatively few rocks present. Much
of the bank area was tree lined until close to the
confluence with the McArthur River •
Sampling in the upstream portion of this stretch showed
that Dolly varden were abundant, comprising 80 percent of
the catch. About half of the catch of Dolly Varden were
fish 10 inches or less in length. Coho salmon juvenile3
and rainbow trout adults were also common. The area
apparently serves as bath nursery and adult habitat for
these species.
The Middle River flows directly to Cook Inlet. Different
stretches of the Middle River were characterized by
different habitat types. The upper sections of the
Middle River, downstream from the division with the
Chakachatna, were characterized by relatively swift
currents, mixed substrates, tree-lined banks, and a
highly variable channel. The substrates varied from
sand-gravel, sand-silt, and gra.vel-cobble. Cut banks
were present as well as tree roots along the banks.
While the upper reaches of the Middle River were
characterized by an abundance of juvenile and adult Dolly
Varden, the area also served as a nursery area for coho
salmon and sockeye salmon. Parr of all three species
were found in areas of law velocity and caver. The river
is also used by sockeye salmon during out-migrations and
by sockeye, coho and chum salmon for spawning
migrations. Sockeye and chum salmon were observed in
August and coho were collected during September. Rainbow
trout adults were also common in the upper river.
However, bath pygmy and round whitefish were common
6-56
....._,____~
throughout the area. Severa! small, unnamed tributaries
enter the Middle River. Sorne of the tributaries are slow
moving and represent flow from old beaver dams. Both
ninespine and threespine sticklebacks were found in these
areas.
In the lower stretches of the Middle River the channel
became wider and slower flowing, and riparian vegetation
became increasingly more marsh like as the river
approached Cook Inlet. The substrate is a fine sand-silt
mud (Figure 6-18) with relatively few outcroppings of
rock and little bank cover. Very few fish were observed
or collected in this area; the most common being
sticklebacks. Only one juvenile Dolly Varden and one
sockeye smolt were collected in this section. There was
no evidence that this stretch was used as a nursery area.
This section was also part of the migratory route of
sockeye, coho and chum salmon. However, no evidence was
collected that indicates that chinook salmon, pink
salmon, or anadromous Dolly Varden use the Middle River
as part of their migratory route.
Although intertidal spawning by both pink and chum salmon
has been reported in Alaska {Bailey 1964, Bailey 1969,
Merrell 1970), it was not observed in the Middle River,
and since the lower Middle River does not contain
suitable cobble or grave! substrates (Bailey 1969,
Merrell 1970, Nikolskii 1961, Morrow 1980), neither
species would be expectcd to spawn there.
The Noaukta Slough is an area of diverse and meandering
channels, islands, pools, and substrates. The slough, as
observed during the two 1981 reconnaissance trips, was
considerably more complex than depicted on existing maps.
6-57
-
-
.....,
-
-----------------------------------------------=----~-~----~------~~-==--~~~
-
,.,._
-
,_,
"-
-
,_
-
The slough included a large number of islands and flooded
wooded areas.
Substrates within Noaukta Slough varied extensively ~iith
large areas of the slough characterized by soft sub-
strates dominated by sand-silt muds, while other areas
were dominated by cobble-gravel substrates. Areas in the
upstream portions of the slough contained greater amounts
of hard substrate than areas further downstream. Riffles
were more common and velocities slightly higher in this
upstream reach.
Sampling in the upstream portion of Noaukta Slough
(Figure 6-17) showed that Dolly Varden were abundant,
comprising 80 percent of the catch. More than half of
the catch of Dolly Varden were fish 10 in. or less in
length. Coho salmon juveniles and rainbow trout adults
were also common. The area also apparently serves as
both nursery and adult habitat for these species.
Both pygmy and round whitefishes were also present in the
Slough. While the pygmy whitefish was more common than
the round whitefish and was often found in areas that
provided caver, round whitefish were often found in
deeper, faster moving water. Since adult, migrating coho
salmon were collected in the upper part of the slough
near the Chakachatna River, it was apparent that the
slough is part of their migratory pathway.
It was also apparen~ that the Noaukta Slough was a major
nursery area since juvenile fish were extremely abundant
in the middle and lower parts of the slough. Coho salmon
parr and Dolly varden parr were the most abundant. How-
ever, juvenile pygmy whitefish and sockeye salmon parr
6-58
f
were also common. Juvenile salmonids were found where
water velocities were low and cover was sufficient. The
habitats utilized included tree roots, rocky bank areas,
eut banks, shallow side channels with cover, snags, and
sunken trees and bushes. Both sockeye salmon parr and
smolt were present in these areas and occurred in a wide
range of sizes. Although sockeye fry usually migrate to
a lake and reside there for one to two years before going
to sea (Foerster 1968), juveniles from the Chakachatna
and McArthur Rivers apparently migrate to Noaukta Slough
and utilize it as a nursery area since a lake is not
accessible.
Although no spawning was observed in the Slough and no
redds found, there was a substantial amount of suitable
substrate present. The presence of turbid water obscured
observations, and only one adult sockeye salmon carcass·
was found in the slough. However it could have washed
down from known spawning areas upstream.
McArthur River
Figure 6-19 shows habitat utilization along the McArthur
River as determined by observations and collections. The
upper McArthur River originates at the McArthur Glacier.
The area near the head waters of the McArthur River was
characterized by boulders, rubble, cobble with intermixed
gravel, and a fairly high gradient. There were ma~y
riffles present and water velocities reached over 4
ft/sec in the main channel. Water temperdtures were
measured at 0.25°C in this area. Although several
samples were taken within that portion of the upper river
stretching to approximately four miles below the glacier
no fish were found.
6-59
-
~
1-l
-
-
""""
-
~
-
._
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-
~
-
.....
---------------~--,..~~~~----.. =------,
In the braided section approximately four miles
downstream from the glacier, the habitat was
characterized by a gravel-cobble substrate and a w.ater
temperature of 3°C. Small riffles and side channels of
varying depth were located throughout this area. In
addition, small clear water streams entered the river
along both sides of the canyon. Fish were abundant in
this section of the McArthur River. Dolly Varden adults,
juveniles and parr were present in this area, however
juveniles of other species were not found.
A number of species were found to use the lower part of
this area for spawning. Chinook, coho, pink, sockeye and
chum salmon were observed spawning in the side channels
of this area. Chinook salmon were observed only during
the August reconnaissance and coho only during September,
but both species appeared to utilize very similar areas.
Sockeye salmon were the most abundant spawning species
observed in this area during the two investigations, and
were found in a great variety of areas including Pond A
(Figure 6.20). Coho spawners began to appear in large
numbers at the end of the September reconnaissance. The
peak abundance of coho spawners in the McArthur may not
actually occur until later in the year {October-November) •
At the conclusion of the September reconnaissance, large
numbers of anadromous Dolly Varden were found in the side
channels of this area. Spawning behavior exhibited by
Dolly Varden in this part of the McArthur had not been
observed in the earlier reconnaissance. Dolly Varden
spawning likely occurs from late August to the end of
November, with peak activity occurring in September and
October (Morrow 1980) •
6-60
Downstream from the braided section of river, juvenile
salmonids representing a variety of species became more
abundant. Juvenile fish found in this section of the
river included Dolly Varden, coho salmon, sockeye salmon,
and pygmy whitefish. Adult pygmy whitefish were also
present in this area. The beaver ponds labeled A and B
were utilized by both sockeye salmon and bolly Varden.
Ninespine sticklebacks were also abundant in these ponds,
but were especially abundant in pond c. The substrates
comprising the lower braided reach to the mouth of the
canyon were increasingly dominated by sand, and ether
fine materials. Juvenile fish were only found along the
far banks of the river in areas with a hard substrate or
cover provided by vegetation. The large open sand flat
areas of the main channels appeared to be devoid of fish,
with the exception of occasional migrants. These
migrants included adult chinook, coho, chum, pink and
sockeye salmon as well as Dolly Varden.
The northern channel of the McArthur River was relatively
shallow with a sand-silt substrate. Fish were generally
found along the banks and in areas that provided cover.
Fyke net catches in this area were smaller than at any of
the ether stations. The species composition was also
different, with the adult fishes being dominated by pygmy
whitefish and a few Dolly Varden. Juveniles in this area
were also less numerous, with only juvenile echo salmon,
pygmy whitefish and Dolly Varden present.
Downstream from this area, several side channels and
islands were present (shown in detail in Figure 6.21,
Area A) • In and around these side channels and islands
there was a variety of cover provided by flooded trees,
6-61
-
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-
-
"-
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·-
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"-
-
't
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--;;::
.... •
l
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~~~ ,
snags, and cobble-rubble substrate. Fish found in these
areas included coho and sockeye salmon juveniles, pygmy
whitefish juveniles, and Dolly Varden parr. Adult
rainbow trout, pygmy, and round whitefish were also found
in these area·s. Very few fish except adult round
whitefish were found away from caver or the channel banks.
The sou.t.hern channel of the McArthur River that origin-
ated from the Blockade Glacier was characterized by a
boulder-rubble-cobble_substrate. Although sorne of the
areas in this stxetch contained c·obble-gravel substrate
that mig:ht: be. suitable for salmonid spawning (Area C in
Figure 6.21~, water temperatures in the area were
probably too low.
Further downstream, the substxate was more diverse. It
contained substantial quanti tie.s of sand with occasional
boulders· and patc:hes of hard substrate. ·water tempera-
tures in this area (B, Figure 6 • .21) wera approximately
3. 5 °C. Sampling in area. B revealed that large numbers of
juvenile fish werepresent in sh3llow areas that provided
cover, l.ow water vecloci ty· and eddies. Juveniles included
sockeye: salmon smal.t and parr, chinook salmon parr, Dolly
Varden, and pygmy w·hitefish. No coho salmon juveniles
were collected in this area.
No adult salmon were found or observed in this part of
the river du.ring either reconnaissance. It is not known
at present whether any spawning occurs in the southern
channel.
In the vicinity of Cook Inlet, the McArthur River sub-
strate was generally· sand-silt/mud. This part of the
river i.s· not expected to provide significant juvenile
6-62
nursery habitat nor spawning areas. It is, however, a
migratory pathway for the anadromous salmonids.
The McArthur River also has a number of tributary streams
that serve as both spawning and nursery areas. The
streams identified by the letters D through H were found
to contain spawning salmonids during one or both of the
reconnaissance efforts (Figure 6.21)• All of the streams
had clear water, a variety of riffle and pool habitats,
and substrate suitable for salmonid spawning. There was
also a great deal of cover along the banks provided by
rubble, eut banks, and overhanging trees. Streams D and
E were found to contain spawning sockeye, chum, pink and
chinook salmon during August 1981. Streams G and F were
also found to contain chum and chinook salmon. Clearly
stream G also served as a migratory pathway for streams E
and F.
Although stream E was found to serve as nursery habitat
for Dolly Varden, chinook salmon and coho salmon, this
was the only upper McArthur tributary stream in which a
juvenile fish was collected.
Stream H was overflown during September 1981 and was
found to contain at least 1000 coho salmon. The stream
contained large stretches of spawning substrate and large
numbers of fish were found at each bend in the stream.
Local people in the Tyonek area also reported that
chinook, pink, and chum salmon can be found in this
stream as well as rainbow trout and Dolly Varden. The
extent to which this stream may be utilized for spawning
by species other than coho salmon is unknown.
6-63
-
~
-
,...;
-
-
6.3.3.3
....
......
Overall these tributary streams represent a major part of
the spawning habitat in the McArthur River drainage and
may be utilized more than the side channels of the main
river.
Habitat Use
For the purpose of a preliminary assessment of habitat
use, the study area was divided into 13 areas that
represented areas of relatively similar habitat and/or
geographie location (Figure 6 22) •
A
B
The lake tributary rivers apparently do not contain
salmon spawning populations and do not appear to be
widely utilized.
The Chilligan and Igitna Rivers were the major sockeye
salmon spawning areas found •
C Chakachamna Lake and Kenibuna Lake represent the major
~ juvenile sockeye rearing lakes and nursery areas.
"-
-
D The area from the outlet of Chakachamna Lake to the
base of the canyon along the Chakachatna River is
primarily a migratory route with sorne use by sockeye
and chum salmon spawners, and by Dolly Varden as a
nursery area.
E The Chakachatna River from the Canyon to the split
with the Noaukta Slough. This area includes sorne
moderately important sockeye and chum spawning areas.
There may be sorne minor spawning by chinook in
channels of this area. This is a major migratory
route for sockeye, chinook, chum, pink and coho
6-64
salmon. There is minor use of this area as nursery
habitat by sockeye and coho salmon, as well as Dolly
Varden.
F Straight Creek and its clearwater t~ibutary. This is
a major chinook spawning area as well as a spawning
area for sockeye, chum, coho, and pink salmon. Dolly
Varden and rainbow trout adults utilize this area as
well. These streams serve as a nursery area for
chinook, coho, and Dolly Varden. These streams are
also part of the migratory routes of all five salmon
species.
G The lower Chakachatna River and Middle Rivers. These
areas are part of the migratory pathways for the five
salmon species. Sorne spawning occurs in the side
channels of the Chakachatna in the upper parts of this
section. Chum salmon appeared to be most plentiful
there, with small numbers of sockeye also present.
This area appeared to be moderately important as a
nursery area for coho, chinook, and sockeye salmon.
Dolly varden juveniles and adults were abundant here
as well.
H The Noaukta Slough. The slough is probably a major
nursery area for the McArthur and Chakachatna drain-
ages. Coho, chinook and sockeye juveniles were
abundant there, as were Dolly Varden and pygmy
whitefish.
I Lower McArthur River. This area is part of the
migratory pathway of the five salmonid species that
spawn in the McArthur drainage or that ascend the
lower Chakachatna River or Noaukta Slough to spawn in
6-65
"""'"
.il
-
-
-
~
-
'-
"-
-
....
-,
J
K
the Chakachatna River drainage. This area provided
nursery habitat for juvenile sockeye, coho and Dolly
Varden.
The area adjacent to the McArthur River Canyon. This
part of the river provided a migratory pathway to the
upper sections of the river (L) and also served as
nursery habitat for coho salmon and Dolly Varden.
The southern channel of McArthur River originates at
the Blockade Glacier and has its confluence with the
northern channel near the Noaukta Slough. This area
served as nursery habitat for chinook and sockeye
salmon as well as for Dolly Varden. It is unknown
whether migratory adult salmon use this area but it
appears to be unlikely.
L Upper McArthur River. This area includes spawning
habitats for chinook, coho, sockeye, chum, and pink
salmon. Anadromous Dolly Varden, in addition to
spawning in this habitat, utilize the middle reaches
as a nursery zone. The lower reaches ~ontaining
sufficient cover were used by sockeye, coho, and Dolly
Varden as a nursery area. Migratory adults of all five
salmon species pass through this area.
M Tributary streams of the McArthur River. All five
salmon species were found to spawn in these streams.
Chinook and coho salmon were more abundant than in the
upper McArthur {area L) • Pink salmon were more
abundant in the streams flowing from the mountains.
The streams were also used as nursery areas by
juvenile Dolly Varden and chinook salmon.
6-66
6.3.4 Summary and Conclusions of 1981 Studies
The 1981 studies, although of limited duration and
consiting of only a limited "look" at the Chakachatna and
McArthur River systems, collected a substantial amount of
data. The data indicated that:
o Large numbers of sockeye salmon utilize Lake
Chakachamna as a nursery area and the Igitna and
Chilligan Rivers as spawning sites.
o Lake Chakachamna may contain sockeye spawning sites.
o Side channels in the Chakachatna River are used as
spawning sites by chum, pink and sockeye salmon.
o Side channels in the upper McArthur River are used
as spawning sites by chinook, chum, coho, pink, and
sockeye salmon, and also by anadromous Dolly Varden.
o Clearwater and other tributary streams are used for
spawning by chinook, chum, coho, pink, and sockeye
salmon.
o The intertidal areas of both river systems do not
contain suitable substrate for salmonid spawning.
o Areas with cover and low water velocities are used
as nursery areas.
o Noaukta slough is used extensively as a nursery
area, particul~rly by coho and sockeye salmon.
6-67
lll!iÎI
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-
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-
-
-
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6.4.1 ._
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o M~gratory pathways for spawning adults and
outmigrant juveniles include most reaches of both
river systems.
Terrestrial Vegetation and Wildlife
Background
The objective of the terrestrial component for the
environmental study of the Chakachamna Hydroelectric
Project was to analytically characterize the vegetative
and wildlife communities. Because this project could
affect the lands and waters of both the Chakachamna and
McArthur drainage systems, qualitative data were
collected throughout the study area and vegetation and
wildlife habitat maps were prepared so that areas of a
sensitive or critical nature could be identified.
Previous investigations conducted in the area by the
Alaskan Departrnent of Fish and Game (ADF&G) and the u.s.
Fish and Wildlife Service (USI'WS) have concentrated on
documenting waterfowl utilization of the coastal marshes
of Cook Inlet. In addition to annual aerial surveys of
the Trading Bay State Game Refuge performed by the
personnel of ADF&G, personnel of USFWS have conducted
aerial swan surveys encompassing the lands in and
adjacent to the refuge. Although the main purpose of
these surveys has been to census waterfowl, information
has also been gathered on bald eagle nest sites, moose
calving grounds, and the occurrence of Beluga whales near
the McArthur River •
6-68
~------------------------------------------------------------------------------------------------------------------~---------,
6.4.1.1
6.4.2
Study Area
As previously discussed, the study area encompasses all
of the lands and waters from the tributaries of
Chakachamna Lake to Trading Bay in Cook Inlet in addition
to the lands and waters of the McArthur drainage system.
Located approximately 60 miles west of Anchorage on the
west side of Cook Inlet, this area supports a wide
variety of wildlife and vegetation.
From the tidal flats in Trading Bay the land rises
slowly, forming a continuous array of marshes, bogs, and
ponds. At the mountains, the land supports a totally
different vegetative community. Overall, eight habitat
types were identified. These areas which are described
in subsequent sections included coastal marshes, the
riparian zones around the streams and rivers, bogs, and
the rocky slopes around the lake.
Study Objectives and Methodology
The major objectives during the vegetative studies were
to describe the vegetative communities within the study
area and to provide vegetation maps at a scale appropri-
ate to delineate wildlife habitats. To accomplish this,
a combination of aerial surveys, ground surveys, and an
analysis of true color aerial photographe were utilized.
Throughout the study period (14-25 September), 22 low
elevation aerial surveys (50-200 feet AGL) were flown in
a random route such that the entire study area was
covered. Two observera on opposite sides of the aircraft
recorded the location and relative abundance of
vegetative stands. In addition, 23 quadrats, each
averaging 2 square miles were selected for ground
6-69
'\oU
...
.li!Oii
-
~
~
' il!'JIIlld
-
-
-
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-
-
....
surveys (Figure 6.23). The quadrat sites were not
selected in a random fashion, but instead were chosen to
be a representative samp1ing of vegetative types in the
area. During these observations, all species of woody
vegetation, the major species of herbaceous vegetation,
and their relative abundances were noted. Fina11y, the
information gathered on each of the quadrats was used in
conjunction with the aerial photographs to interpret the
vegetative composition of the remainder of the study area.
The primary objective of the wild1ife study was to
identify important wildlife resources in the study area,
their use of the area, and the importance of identified
vegetative and aquatic communities to these resources.
To accomplish these objectives, the same 22 low elevation
aeria1 surveys that were used to identify vegetative
types were used to classify bird and large mamma1
distribution and abundance. These observations tota1ed
12.8 hours and were conducted at various times of the
day, ranging from 0730 to 1900 hours. In addition to the
aerial surveys, the 23 quadrats used for vegetative
analysis were searched for evidence of birds and mammals.
Forage areas were studied to determine the species and
number of individuals uti1izing the area as we11 as the
species that were being consumed. The identification of
tracks yielded additional information on both nocturnal
and uncommon species and the analysis of scats further
defined the species composition, distribution, and food
habits.
Due to the difficulty in observing small rodents, a
qualitative trapping program was conducted along
transects in five representative zones of the study
area. These five areas were located at the mouths of the
6-70
6.4.3
6.4.3.1
Chilligan and Nagishlamina Rivers, along the edge of the
floodplain on the Chakachatna River near the confluence
with Straight Creek, in the heavily wooded area west of
the Chakachatna River, and on McArthur Flats near Seal
Slough. At each location, 40 snap traps were set for a
period of 48 hours.
Vegetation and habitat type maps were prepared based on
the classification methodology outlined by Phister et al.
(1977) • After the field data collections, a subjective
grouping of possible types was developed, based on
structural differences in the vegetation. Second, a
Bray-Curtis ordination was applied which provided a
graphical arrangement of the types based on similar
species composition. The vegetation type terminology for
this classification differs from most type approaches in
that the understory species named could either be an
understory dominant or simply be an indicator species
{important just by its presence or absence). Overall,
this classific~tion scheme is more directly related to
habitat types than a dominant species approach because it
is sensitive to both veg~tative structure and relative
species composition.
Results and Discussion
Vegetation
Within the study area, 40 species of woody vegetation and
nine taxa of herbaceous veg~tation were identified. Paper
birch had the highest frequency among the woody species,
having been found in 65 percent of the quadrats. Black
cottonwood had the second highest frequency (61 percent)
while diamondleaf and feltleaf willow both occurred in 13
6-71
~
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-
of the 23 quadrats (57 percent). Grasses had the highest
frequency among all the plants, having been found in all
23 quadrats sampled. Although not all of the grasses
present were identified, two of the most common were Poa
sp. and Fetuca sp. The remaining eight taxa of
herbaceous plants were fairly site specific with only
horsetails being found in more than 50 percent of the
quadrats.
Based on the vegetation classification scheme outlined
earlier, the terrestrial vegetation within the study area
was divided into eight types (Table 6.10 and Figure 6.24):
Upland Alder Thicket (UAT);
High Altitude Riparian (HAR);
Black Cottonwood Riparian (BCR) i
Coastal Marsh Riparian (CMR);
Black Spruce Transitional (BST) i
Resin Birch Bog (RBB);
Willow Thicket Riparian (WTR);
and Black Spruce Riparian (BSR)
Upland Alder Thicket
This type occurred mainly on the steep slopes above
Chakachamna Lake and on the canyon walls above the
Neacola, Igitna, Chilligan, Nagishlamina, and McArthur
Rivers. It was also interspersed with the other types on
Kustatan Ridge near Cook Inlet. These sites were
characterized by an abundance of black cottonwood, Sitka
alder, and paper birch. Diamondleaf and feltleaf willow
were abundant in some locations while herbaceous plants
were uncommon, except for grasses.
6-72
High Altitude Riparian
This type was more restricted in its distribution, being
found only on the floodplains of the rivers flowing into
Chakachamna Lake and in the Chakachatna River canyon.
This form of riparian habitat was characterized by an
abundance of Sitka alder, paper birch, and white spruce.
Diamondleaf and feltleaf willow were also widespread.
Herbaceous plants included ferns, fireweed, and moderate
amounts of grasses.
Black Cottonwood Riparian
At elevations lower than the McArthur and Chakachatna
River canyons, this type replaced the high altitude
riparian and was found along the shores of most of the
streams and rivers. Characterized by an abundance of
black cottonwood, thinleaf alder, and paper birch,
numerous species of willow were also present, including
diamondleaf, feltleaf, Barratt, undergreen, and grayleaf.
Herbaceous plants include Artemesia tilesii, ferns,
sedge, and fireweed.
Coastal Marsh Riparian
This type encompassed most of the area within one mile of
Cook Inlet in addition to a few areas along the McArthur
River. These sites were characterized by almost a total
absence of woody vegetation, and an abundance of grasses,
sedge, and horsetails. These sites were better drained
than the bogs and were laced with an array of ponds and
streams that were often inundated by fluctuating tides.
6-73
r r f r { i I
Table 6.10. The species composition and relative abundance of plants identified within the
study area for each of the vegetative types. (l=Dominant 2=Abundant 3=Common
4=0ccasional 5=Rare)
Habitat a
Species UAT HAR BCR CMR BST RBB WTR BSR
black cottonwood Populus trichocarpa 1 4 2 5 4 1
Sitka alder Alnus sinuata 1 1 4 4 3
thinleaf alder Alnus tenuifolia 4 1 3 3 2 3
paper birch Betula papyrifera 2 1 2 5 3 3 4 4
resin birch Betula glandulosa 4 1
dwarf arctic birch Betula nana 4 3 3
quaking aspen Populus tremuloides 4 5
black spruce Picëaïü'ariana 4 4 1 1
white spruce P1cea glauca 4 3 3 5 3
0'1 diamondleaf willow Salix planifolia 2 2 5 5 5 3 1 1
1 feltleaf willow Salix alaxensis 2 2 2 4 2 2 -....]
*'" Barratt willow Salix barrattiana 4 3
undergreen willow Sal1x commutata 4 4
grayleaf willow Salix glauca 4 4 3
Alaska bog willow Salix fuscescens 5 3 4
barren-ground willow Sal1x brachcarpa 5
Richardson willow Salix lanata 5 5 4
Sitka willow Salix sitchensis 5 4
skunk currant Ribes glandulosum 4
American red currant Ribes triste 4 3 5 4 4
trailing black currant Ribes layiflorum 3 5
American red respberry Rubus idaeùs 4 4 5 5
Pacifie red elder Sambucus callicarpa 4 5 4 5
high bushcranberry Viburnum edule 4
mountain-cranberry Vaccinium vitis-idaea 4 4 4
early blueberry Vaccin1um oval1fol1um 4
bog blueberry Vaccinium uliginosum 4 2 3
bunchberry Cornus canadensis 5
crowberry Empetrum n1grum 4 3 4 4
Table 6.10. Concluded
Habitat a
Species UAT HAR BCR CMR BST RBB WTR BSR
saskatoon serviceberry Amelanchier alnifolia 4 4 3
Pacifie serviceberry Amelanch1er flor1da 5
Labrador-tea Ledum groenlandicum 4 3 4
narrow-leaf Labrador-tea Ledum decumbens 5 2
prickly rose Rosa ac1cular1s 4 4
sweetgale Myrica gale 5 4 3 3
rusty menziesia Menziesia ferruginea 3 5
bog rosemary Andromeda pol1folia 4 3
bush cinqfoil Potentilla fruticosa 4 2
leatherleaf Chamaedaphne calyculata 5 4
devilsclub Oplopanax horridus 5 5 5
0'1 fireweed Epilobium sp. 3 3 4 5 4 1
-...] sedge Carex sp. 5 2 5 3 3
""" Gramminaea 3 3 3 1 3 2 3 2 Ill grass
Fern Polystichum sp. 5 5 4
Eriophyllum lanatum 5 4 5
Horsetail Equisetum sp. 4 4 3 5 4 5 4
Angelica genuflexa 4
Artemesia tilesii 5 5 5
lupine Lupinus sp. 5
aUpland Alder Thicket (UAT);
High Altitude Riparian (HAR);
Black Cottonwood Riparian (BCR) ;
Coastal Marsh Riparian (CMR);
Black Spruce Transitional (BST);
Resin Birch Bog {RBB) ;
Willow Thicket Riparian (WTR) ; and
Black Spruce Riparian (BSR) •
...
f,, Î. L ( ' (
...,
~-
-
-
-
-
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~-
-
-'
-
._,
----------------------------------
Black Spruce Transitional
This type was very limited in its distribution, mainly
composing the later successional stages in and around the
open bogs. Characteristic of an ecotone, these sites
hosted a mixture of riparian species (black cottonwood,
thinleaf alder, and paper birch) and bog species (black
spruce, bog rosemaryr and bog blueberry). Herbaceous
taxa were well represented in both number and distri-
bution. Physically, these sites were also intermediate
between bog and riparian sites with part of the area dry
a~d well drained while other areas were wet and spongy.
Resin Birch Bog
Although this type was found throughout the lower
elevations of the study area, it dominated the area north
of Noaukta Slough. Characterized by a predominance of
bog shrubs such as resin birch, bog blueberry, and
narrow-leaf Labrador-tea, these areas also hosted an
abundance of herbaceous pla~ts including sedge and
grasses. Physicallyr these sites were poorly drained and
supported large mats of floating vegetation.
Willow Thicket Riparian
The distribution of this type was limited~ only being
found along the floodplain of the McArthur River c~nyon.
This riparian area was characterized by an abundance of
willows (seven species) , black cottonwood, and thinleaf
alder. Herbaceous plants were sparse but included
fireweed, grasses, and lupine.
6-75
6.4.3.2
Black Spruce Riparian
This type was common at intermediate elevations, between
the higher elevations of the Resin Birch Bog and the
lower elevations of the Coastal Marsh Riparian and was
the dominant type found on the Trading Bay Refuge. These
areas were characterized by an abundance of diamondleaf
willow, black spruce, and an absence of black cotton-
wood. Both species of alder were present along with an
abundance of sedge and grasses. Physically, these sites
were poorly drained, but unlike the bog, there was no mat
of floating vegetation to caver the large amounts of
water.
Mammals
Of the 16 species of mammals that were identified, the
grizzly bear, black bear, and moose had ranges occurring
throughout the study area. Also common were the coyote
and gray wolf, bot~ of which were found in more than 50
percent of the quadrats sampled. Less common mammals
included the river otter, barren ground caribou, and
wolverine.
The same eight habitat types used to classify the
terrestrial vegetation were also used to classify the
distribution and relative abundance of the mammals that
occurred in the study area (Table 6.11). Grizzly bears,
black bears, and moose were found to utilize all eight
habitat types. During the two weeks in September that
this study encompassed, the grizzly bear appeared to be
most abundant in the High Altitude Riparian and Black
Cottonwood Riparian habitats. The black bear appeared
most abundant in the Upland Alder Thicket and High
6-76
..,
...
""""
1
(J)
1
-....!
-....!
(, 1 r f 1 c f f f f f -f
Table 6.11 The species composition and relative abundance of mammals identified within
the study area for each of the habitat types. (l=Abundant 3=Common 5=0ccasional)
Species
grizzly bear Ursus horribilis
black bear Ursus amer1canus
gray wolf Canis lupus
coyote Can1s latrans
mo ose Alces alces
barren ground caribou Rangifer arcticus
wolverine Gulo luscus
mink Mustela vison
river otter Lutra canadensis
bea ver Castor canadènSis
muskrat Ondatra zibethica
red squirrel Tamiasciurus hudsonicus
tundra redback vole Clethrionomys rutilus
tundra vole Microtis oeconomus
porcupine Erethizon dorsatum
dusky shrewb Sorex obscurus
harbor seal b Phoca vl.tulina
beluga whale Delphinapterus leucas
a Upland Alder Thicket (UAT);
High Altitude Riparian (HAR);
Black Cottonwood Riparian (BCR);
Coastal Marsh Riparian (CMR);
Black Spruce Transitional (BST);
Resin Birch Bog (RBB);
Willow Thicket Riparian (STR); and
Black Spruce Riparian (BSR).
Habitata
UAT HAR BCR CMR BST RBB WTR BSR
3
l
5
3
5
5
5
5
l
3
1
1
3
3
1
5
5
5
5
5
3
3
3
3
3
5
3
1
5
3
5
3
3
5
3
3
3
3
3
3
5
1
3
5
3
5
5
5
5
5
5
3
3
5
3
5
3
3
3
3
3
3
5
3
3
5
5
5
3
3
3
3
3
3
5
3
5
3
3
5
h . -sighted offshore near the mouth of the McArthur River.
1
Altitude Riparian habitats, while the moose was most
abundant in High Altitude Riparian and Black Cottonwood
Riparian .habitats. Unlike the distribution of most of
the other mammals, moose were common in all habitats
except in the upland Alder Thickets.
The only other ungulate that occurred in the project area
besides moose was the barren ground caribou, and its
distribution was restricted to the High Altitude Riparian
habitat. Both species of Canids that were present,
occurred over a fairly large range. Although not as
abundant as the coyote, the gray wolf was found in all
habitats except the Resin Birch Bog and the Black Spruce
Riparian while the coyote was found in all eight types.
The order that was best represented in the study area was
Rodintia. The two largest members of the order, beaver
and porcupine each occupied three habitats while the
muskrat inhabited four types.
The habitat type that had the highest diversity (as
measured by the number of species) was the Black
Cottonwood Riparian. This habitat contained 15 of the 16
mammals found in the study area. The lowest diversity
(five speèies) was found in the Resin Birch Bog habitat.
The analysis of scats, tracks, and feeding areas supplied
additional information on the seasonal distribution and
food habits of some species. Both species of bears
appeared to be consuming berries, salmon, and grasses.
Although the direction of travel for most of the bears
was towards the High Altitude Riparian habitat it is not
known if this is indicative of the location of winter
denning sites. During the two weeks of this study, moose
6-78
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·-
""'"'
'"'"'
-6.4.3.3
-
--------------·--' ·-"'M" -M
were feeding mostly on willows that were taller than five
feet and were seldom seen very far from tall dense
vegetation. Calving grounds, as indicated by the
skeletal remains of juvenile moose, appeared to be
located in and near the Black Cottonwood Riparian habitat
around the Middle River, Noaukta Slough, and the McArthur
River. Wintering areas, as indicated by shed antlers,
were found throughout the High Altitude Riparian habitat
above Chakachamna Lake. Beaver, otter, and muskrat had
more limited distributions. While beaver and muskrat
were found ~hroughout the Black Cottonwood Riparian,
Willow Thicket Riparian, and Black Spruce Riparian
habitats, porcupine were found in the High Altitude
Riparian, Bla~k Cottonwood Riparian and Coastal Marsh
Riparian habitats. Areas that are utilized by these
mammals were identified by the presence of beaver lodges,
woody plants, chewed by beaver, muskrat bouses, otter
slides and tracks.
In addition to the terrestrial :mammals, two species of
marine mammals were present. A harbor seal was sighted
at the mouth of the McArthur River ar.d although Beluga
whales were not observed during this study, personnel of
ADF&G have sighted whales in Trading Bay.
Birds
Within the study area, 56 species of birds were
identified. Of these, the three that occurred in all 23
quadrats sampled, were the bald eagle, common raven, and
black-billed magpie. Also common in the area were marsh
hawks, black-capped chickadees, and various species of
6-79
·-----------------------------------------------------r
waterfowl. Species that were only sighted occasionally
included fox sparrows, Swainson's hawks, brown creepers,
and snow buntings.
The same habitat types that were used to describe the
distribution of mammals and vegetation were used to
describe the distribution and relative abundance of the
56 species of birds (Table 6.12). The habitat that
hosted the largest diversity of avifauna was the Coastal
Marsh Riparian. Included is the 38 species sighted in
that type were trumpeter swans, bald eagles, black
bellied plovers, short-billed dowitchers, and lapland
longspurs. The Upland Alder Thicket type only hosted 10
species, most of which were common throughout the study
area. Nearly as low in species richness were the Resin
Birch Bog and Willow Thicket Riparian habitats,
containing 11 and 12 species of birds, respectively.
Two of the larger species that nest in the study area are
the bald eagle and the trumpeter swan (Figure 6.25}. As
of May 1980, ADF&G personnel had documented the location
of five eagle nests on the Trading Bay Refuge. During
this two week study, eagles were observed from the
Chilligan River to Cook Inlet, however, they were
concentrated near the confluence of Straight Creek and
the Chakachatna River. In August, 1980, personnel of
USFWS recorded the location of trumpeter swan nests in
and near the refuge. At the time of the survey, there
were 25 pairs of breeding swans and a total of 143 swans
in the project area. Similar to the distribution of
eagle nests, swan nests were concentrated near Cook
Inlet. The area within seven miles of the tidal mud
flats provided habitat to 55 percent of the total
6-80
f
-
-
•
y
-
-
-
,_
~
,_
-
v
-
,_
...,..
-
'-'
-
--
'-'
-
population, 48 percent of the nesting pairs, and 63
percent of the fledgling cygnets {Figure 6.26). Although
the largest proportion of the population was near Cook
Inlet, the area with the highest density was from Noaukta
Slough to the Blockade Glacier, along the McArthur River.
This area, encompassing 70 square miles, contained 56
trumpeters (0.8 swans/mile2).
A species that is commonly found feeding in the study
area, (Timm and Sellers, 1981) yet was not observed
during this study, is the tule white-fronted goose (Anser
albitfrons gambelli). Currently, the only known nesting
areas for the tule goose in Cook Inlet are at Redoubt Bay
and Susitna Flats. Although personnel of USFWS and ADF&G
have searched the study area for nesting pairs, no
evidence exists that would support the contention that
this species nests on the Trading Bay Refuge. However,
since this species often nests in dense vegetation,
undetected nesting sites may exist.
6-81
0\
1
00
N
Table 6.12. The species composition'and relative abundance of birds identified within the
study area for each of the habitat types. (l=Abundant 3=Cornmon 5=0ccasional)
Species
trumpeter swan
Canada goose
white-fronted goose
mal lard
pintail
American wigeon
green-winged teal
greater scaup
cornmon goldeneye
oldsquaw
cornmon merganser
red-breasted merganser
sharp-shinned hawk
marsh hawk
red-tailed hawk
Swainson's hawk
bald eagle
spruce grouse
willow ptarmigan
sanhill crane
black-bellied plover
spotted sandpiper
greater yellowlegs
short-billed dowitcher
pectoral sandpiper
least sandpiper
northern phalarope
cornmon snipe
glaucous-winged gull
herring gull
mew gull
Olor buccinator
Branta canadensis
Anser albifrons
Anas platyrhynchos
Anas acuta
Mareca americana
Anas carolinensis
Aythya marila
Bucephala clangula
Clangula hyemalis
Mergus merganser
Mergus serrator
Accipiter striatus
Circus cyaneus
Buteo jamaicensis
Buteo swa1.nson1.
Haliaeetus leucocephalus
Canachites canadensis
Lagopus lagopus
Grus canadensis
squatarola squatarola
Actitis macularia
Totanus melanoleucus
Limnodromus griseus
Erolia melanotos
Erolia m1.nut1.lla
Lob1.pes lobatus
Capella gallinago
Larus glaucescens
Larus argentatus
Larus canus
Habitat a
UAT HAR BCR CMR BST RBB WTR BSR
5
5 5
5 5
5 3
3 3
5 3
5 3
3
5
5
5
3
5
3
3
5
3
5
3
3
3
1
1
1
1
5
5
5
3
3
5
5
3
5
3
5
5
5
3
1
5
5
5
3
3
5
5
5
5
5
3
5
5
5
5
5
5
5
5
3
5
5
5
3
3
3
3
5
3
0"1
1
00
w
1 ( i f j . l f ,-
Table 6.12. Concluded.
Habitata
Species UAT HAR BCR CMR BST RBB WTR BSR
arctic tern
short-eared owl
hawk owl
belted kingfisher
hairy woodpecker
bank swallow
gray jay
black-billed magpie
common raven
black-capped chickadee
boreal chickadee
brown creeper
hermit thrush
ruby-crowned kinglet
water pipit
yellow warbler
common redpoll
pine siskin
savanah sparrow
dark-eyed junco
tree sparrow
chipping sparrow
fox sparrow
lapland longspur
snow bunting
Sterna paradisaea
Asio flammeus
Surnia ulula
Megaceryle alcyon
Dendrocopos villosus
R1par1a r1par1a
Perisoreus canadensis
Pica pica 3
oorvus-ëërax 3
Parus atricapillus 1
Parus hudsonicus
Certhia familiaris
Hylocichla guttata
Regulus calendula
Anthus spinoletta
Dendroica petechia
Acanthis flammea
Spinus pinus
Passerculus sandwichensis
Junco hyemalis
SpizelraiarbOrea
Spizella passerina
Passarella 1liaca 5
Calcarius lapponicus
Plectrophenax nivalis
5
3
3
1
5
5
3
3
3
5
5
5
3
5
3
3
3
5
3
5
5
3
5
3
3
3
5
3
5
3
3
5
3
3
3
3
3
5
3
3
3
5
5
5
5
5
5
5
3
a Upland Alder Thicket (UAT);
High Altitude Riparian (HAR);
Black Cottonwood Riparian (BCR);
Coastal Marsh Riparian (CMR);
Black Spruce Transitional (BST);
Resin Birch Bog (RBB);
Willow Thicket Riparian (WTR); and
Black Spruce Riparian (BSR).
5
3
3
5
5
5
5
3
3
1
3
3
3
3
5
3
3
5
f
1
\
6.4.4
Of all of the species of plants, mammals, and birds that
were identified in the study area, none of the species
that a+e present are listed as threatened or endangered
by the Federal Government. However, as of May 1981, it
was proposed that the tule goose be considered for
threatened or endangered status (M. Amaral, USFWS,
personal communication 2 November 1981).
Conclusions
The relatively high diversity in both flora and fauna
found within the study area is the product of climate
topography and fluctuations in the stream and river
discharge. Due to periodic tidal inundation of the
coastal marshes, both salt water and brackish marsh
vegetation is found. Surface flows resulting from
precipitation are apparently retained for long periods of
time in bogs. Combined with these factors are dynamic
river channels and varying successional stages. As a
result. the study area is composed of a variety of
vegetation types that, individually and collectively
provide important habitat to species of wildlife
throughout the year. Although all species of plants and
animals· in the area are important, there are several
vegetative ~ypes that are more critical to the overall
stability of the community than others. Two of these are
the High Altitude Riparian and the Black Cottonwood
Riparian habitats. These areas not only provide food and
cover to a wide variety of animal life throughout the
year, they also provide wintering and calving grounds for
moose, nesting sites for bald eagles and trumpeter swans,
and feeding areas for grizzly and black bears. The other
two critical areas are the Coastal Marsh Riparian and the
6-84
-
""'~
'-
-
6.5
'-""
6.5.1
,_
-
-
-
-
,_
Black Spruce Riparian habitats. Due to the large
expanses of standing water and dense vegetation, these
areas provide nesting and staging areas for waterfowl and
shore birds.
Hurnan Resources
Background
The Hurnan Resoûrces element of the report was prepared
with several objectives in rnind:
(l) identification of concerns of governrnent agencies
and general public
(2) evaluation of project alternatives,
(3) conforrnance with FERC guidelines, and
(4) preparation of the 1982 scope of study.
Accordingly six areas of study wer~ selected:
archaeological and historical resources, land ownership
and use, recreation, socioeconomics, transportation, and
visual resources.
The general project area has a long and varied history of
hurnan habitation, and therefore has a high potential for
archaelogical and historical resource sites. However,
little field work has been done in the project area and
the distributrion of potential resource sites is unknown.
Federal and State agencies and ~ative corporations
involved in the proposed project have varying
requirernents for the protection of archaeological and
historie resources.
6-85
As elsewhere in the state, land is owned by a mix of
federal, state, Native, and private entities. The status
of land selections, conveyence and patents is complicated
and often involves several parties in the manaqement of
one parcel of land. Land,use revolves around resource
extraction, processing, and transportation.
Recreational use of the project area is currently
limited, but increasing in popularity. Recreation
activities in neighboring Lake Clark National Park and
Trading Bay Game Refuge could have a bearing on the
project. In addition, the State.Division of Parks will
be inventorying recreation resources in western Cook
Inlet in the near future and is interested in the
Chakachamna River area.
Project construction and operation will both create jobs
and impact the socioeconomic characteristics (population:
employment, income, infrastructure and subsistence) of
the region. Impacts will affect the village of Tyonek,
the Kenai Peninsula Borough, and the greater Anchorage
area.
The remoteness of the project site emphasizes the
importance of existing transportation networks. Project
use of roads, docks, and air strips may conflict with
existing uses, and new facilities required for the
project may provide new public access that is not desired
by local residents.
Both the Bureau of Land Management and FERC have specifie
requirements regarding visual resources. The scenic
nature of the project area led to its consideration for
inclusion as national interest lands under Section
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6.5.2.1
6.5.2.2
17{d)-2 of the Alaska Native Claims Settlement Act.
Project proximity to Lake Clark National Park and Trading
Bay State Game Refuge may place more importance on visual
resource impacts.
This Human Resource element was prepared using three
methods. Field reconnaissance was employed to evaluate
the potential for archaeological resource sites. Several
recent reports associated with coal and petroleum
resource development proposals were also utilized.
Finally, federal, state, and Native entities were
contacted to obtain resource data and concerns about the
project.
Archaeological and Historie Resources
Introduction
This section evaluates the historie and archaeological
resources of the area through a literature review,
personal contacts, and consultations with the State
Historie Preservation Officer and the State
Archaeologist. A one day helicopter reconnaissance
allowed a field evaluation of the power generation
facility sites.
Historical Background
The project area lies within the traditional territory of
Tanaina Athapaskan Indians. The earliest record of
European contact with the Tanaina resulted from Captain
James Cook's voyage to the upper inlet in 1778 (Cook
1784). In July of 1786, two English ships captained by
Dixon and Portlock made a trading trip to Cook Inlet.
6-87
The bay in which they anchored was named Trading Bay by
Capt. Portlock. Trading lasted for about a week (Dixon
1789; Portlock 1789). During this same period Russian
presence was increasingly more evident in the Cook Inlet
region (Bancroft 1886; Townsend 1965).
After the Russians settled in the area there began a
period of struggle between the various Russian trading
companies. The Tanaina were caught up in this struggle
and open hostilities broke out between the Tanaina and
the Russians. The Russian American Company was founded
in 1799 11 (Van Stone and Townsend 1970:14). An outpost
had been estab1ished by the Russians at Tyonek around
1790. In 1797 the Tyonek Outpost was destroyed.
11 Dissension among the Russians and persecutions of the
Natives reached such an extreme that the infuriated
Kenais (Tanaina) destroyed the two outposts at I1iamna
and Tuiunuk (Tyonek), killed 20 Russians, and a1most 100
subject natives .. (Tikhmenev 1978:46).
After 1800, hosti1ities between the Tanaina and the
Russians seem to have subsided. This relative1y peacefu1
period saw renewed trade and the introduction of
Christianity (Townsend 1965:55). Unfortunately, a
sma11pox epidemie swept through the region in the late
1830s.
With the sale of Alaska to the united States in 1867 the
Russian-American Company assets were purchased and
reorganized to form the Alaska Commercial Company. The
Alaska Commercial gained a virtual monopoly in 1883 after
the Western Fur and Trading Company sold out.
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During the late 1890s and early 1900s, Tyonek became a
major disembarking point for both goods and people as
prospectors and miners moved into the Cook Inlet region.
Aboriginal use of the project area appears to have been
extensive and ancient. Extensiv~ use of severa! mountain
passes and trails is well documented for the late
prehistoric/early historie period. The Tanaina from the
Tyonek area utilized the interior region for hunting and
trading purposes as did the inland Tanaina groups from
Lake Clark, Mulchatna, Stony River, and the Susitna
basin. Key subsistence items for the Tyonek Tanaina,
however, centered on marine resources. Procurement of
food items such as salmon, eulachon, seal, and beluga
made it possible for the Tanaina to maintain semi-
permanent villages along the coast. In late April the
Tyonek Tanaina would move to traditional fish camps along
the inlet. Waterfowl were caught at tidal flats and at
the mouths of rivers along Trading Bay. Beluga and
Susitna flats were also used. During the spring, fish
traps were set for trout at interior lakes. Beaver were
also hunted inland at streams and lakes (Chickalusion and
Chickalusion 1979) • The favored land hunting area for
the Tyonek Tanaina was the region around Chakachamna
Lake. Inland hunting was concentrated during late August
through October. Moose seemed to be scarce throughout
the region during early historie times. In addition to
hunting in the Chakachamna Lake region the Tyonek people
would sometimes cross the Hayes River Pass (Tubughna
Kalidiltuni) to Rainey Pass (Ht~) to hunt caribou and
sheep. Here they would meet and trade with Susitna
Tanaina (Fall 1981:193).
6-89
The Tyonek people had a tradition of trading with other
groups from the interior. They would meet upper
Kuskqkwim Natives at Merrill Pass in the summer or fall
to conduct trading. Apparently the Tanaina enjoyed the
role of middleman traders between the Russians at Cook
Inlet and the deep interior upper Kuskokwim Indians
(Zagoskin 1967:16B-169).
A review of the archaeological literature indicates that
the project area and immediate vicinity have not been
studied. Most of what is known of the prehistory in the
Cook Inlet region pertains to the western side of Knik
Arro {de Laguna 1975; Dumond and Mace 1968), the northern
shore of Turnagain Arm (Reger 1977b, 1981), Kenai
Peninsula (Kent et al. 1964; Borras 1975, 1976; Reger
1977a), Kachemak Bay (de Laguna 1975; K. Workman 1977; W.
Workman 1977), and the Matanuska River (West 1975, 1980;
Bacon 1978). The only archaeological investigation very
close to the project area is that of de Laguna at
Kustatan in 1930. She briefly investigated a prehistoric
midden on the first bench behind the cannery •. On the
second bench she observed several house pit depressions
and excavated one of them {de Laguna 1975:138). De
Laguna commented that a1though the collection was meager
(faunal remains and a few artifacts) it appeared simi1ar
to Kachemak Bay collections (de Laguna 1975:148).
The following out1ine of Cook Inlet prehistoric cultural
events is based upon Reger's recent summary (Reger 1981).
A. The earliest cultural remains recognized in the Cook
Inlet region are from component I at the Beluga
Point-North site on Turnagain Arm. It consists of a
core and microblade technology which can be compared
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to other sites dating between 8000 and 10,000 years
ago. These sites fall within the broad American
Paleoarctic tradition described by Anderson
(1968:29). This tradition includes collections from
interior Al.askan locations such as Dry Creek {Nenana
Valley), Healy Lake (Tanana Valley), and Onion Portage
(Kobuk Valley). These sites have consistently been
associated with an environment thought to support
herds of bison, horse, mammoth, and caribou. Thus,
these early cultures are believed to have been
primarily exploiters of large land mammals. Heusser's
reconstruction of the early post-glacial vegetation
for southcentral Alaska postulates generally treeless
tundra and somewhat moister conditions than the deep
interior (Heusser 1960). A greater expanse of tundra
than at present would have been able to support a
large number of caribou.
B. The next occupation in the sequence is found in Beluga
Point-North component II and Beluga Point-South
component I. Artifact comparisons with surrounding
geographie areas, i.e., the P~aska Peninsula, Afognak
Island, and Lake Iliamna indicate an age of 3000 to
4000 years old.
C. Norton related culture (cf Dumond 1977:106) is
represented by Beluga Point··South component II. "The
time period of approximately 1500 to 3000 years ago
was a period in which influences (Norton culture) from
Bristol Bay diffused into Cook Inlet as indicated by
the BPS-II collection .. (Reger 1981:202). Although
there was a fairly strong Norton influence during
early Norton times, the archaeological record
indicates that cultural influences between Bristol Bay
and Cook Inlet had ceased during late Norton times.
6-91
6.5.2.3
D. Reger suggests that Kachemak culture (de Laguna 1975),
which flourished in the Kachemak Bay area, may have
provided a mechanism for limiting Norton influences in
the Cook Inlet area. He feels that between 1500 to
2000 years ago a separate cultural pattern developed
in the upper inlet which was based on seasonal use of
riverine and interior resources "Such a pattern
appears to be evident at the Moose River site and the
Merrill site, and by ,inter-pretatio~ will probably be
found in the Upper Inlet area 11 (Reger 1981:205).
E. Between 600 and 800 years ago another cultural
oqcupation was present at Beluga Point, Beluga
Point-North component III. This component is distinct
with only a few traits showing close comparison with
nearby collections, i.e., from Prince William Sound,
Kodiak Island, and Kachemak Bay. The presence of
native copper implements indicates trade contacts w1th
interior Indian groups, possibly Atna Athapaskans of
the Copper River country.
F. The late prehistoric period in the upper Cook Inlet
region is poorly documented. It is generally believed
that interior Athapaskan influences were introduced by
the arrival of Tanaina Indians, perhaps during the
second half of the 18th century A.D.
Methodology and Results
The Alaska Heritage Resource Survey File (AHRS),
maintained by the State Historie Preservation Office, was
searched for any reference to historie or archaeological
sites at or near the Chakachamna Hydroelectric Project.
No sites are listed for the project area. A review of
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the archaeological, ethnological, and historical
literature indicates that the project area has not been
well studied.
The potential for prehistoric human use and habitation
within the project area is moderately high. The
literature indicates that prehistoric peoples were
ranging throughout the Cook Inlet and Susitna basin
region over many thousands of years, perhaps as early as
8000 B.C •• Severa! diverse cultural traditions have
exploited the region. Thus far, nearly all of the
archaeological investigations in th~ Cook Inlet region
have been at coasta~ sites. The interior exploitive
pattern has only recently been investigated.
De Laguna made note of four old village sites between
Trading Bay and Beluga River, although she did not visit
any of them.
Ladd. The modern village is on an ancient site,
Tsluiltna from which the name of the river, Chuit, is
probably derived.
Tyonic or Moquawkie. There is an old village site,
Qalqesle, near the modern village. In the woods at
the top of the hill behind the village are the bouses
where the natives used to live for fear of raids made
by the Kodiak Eskimo.
Old TyOnic. This village is called Tatlnaq, and may
be old. This seems to be the "Toyonek" of Petroff's
map.
Granite Point. The site of Tsilalxna is at a small
stream south of Granite Point (de Laguna 1975:139).
6-93
The one-day helicopter reconnaissance provided an
overflight of the potential power generation facility
sites, on the southeast shore of Chakachamna Lake and
near the upper limits of McArthur River. The lake shore
in sections 18 and 19 of Township 13N/Range 17W and
section 24 of Township 13N/Range 18W, Seward Meridian was
examined from the air. There was no landing area for the
helicopter because the steep, rocky slope decends
abruptly into the lake and the helicopter was not
equipped with pontoons. The possibility of any impact to
cultural resources resulting from the facility at
Chakachamna Lake is so unlikely that an on-the-ground
archaeological survey is not considered necessary.
The porbable location of the powerhouse lies somewhere
within section 30 of Township 12N/Range 17W, Seward
Meridian. This area, a small narrow valley with steep
walls, was examined from the air only. Although it
appears unlikely that any cultural resources will be
impacted by the facility, an on-the-ground archaeological
clearance should be done after the exact location is
selected. and the limits of the construction zone
determined, but prior to the actual construction.
Because transmission line corridors and access road
alignments have yet to be finalized, only a
reconnaissance flight over the broad zone of probable
impact was possible. It is here that potential impacts
to cultural resources are most likely to occur,
especially with the building of roads and development of
borrow pits. Therefore, archaeological on-the-ground
survey will be necessary prior to any construction
activities involving transmission lines and roads.
6-94
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6.5.3
6.5.3.1
The likelihood of archaeological site occurrence can be
depicted on maps as areas classified high, medium, and
low potential. Such areas can be identified using basic
criteria of vegetation communities, physiography, slope,
aspect, soils, and proximity to resources such as food,
fuel, raw materials, and wate~. Mapping of archaeo-
logical potential can be aided by air photo inter-
pretation, but primarily depends on the judgement of the
archaeologist. This judgement is based upon experience
in site survey, familiarity with specifie geographical
areas, and the data base of identified archaeological
sites found in similar environmental settings throughout
Alaska.
Areas of low potential are generally flat wetlands or
have high topographie relief. Either condition is
restrictive to human habitation. Low potential areas
also include active floodplains where periodic flooding
and erosion would have destroyed evidence of past human
activity. High potential areas are generally those with
moderate topographie relief which ordinarily are
well-drained. Areas of medium potential might include
sorne portions of high and low potential but are not
classified predominately high or low.
Land Ownership and Use
Land Ownership
.Figure 6-27 shows the existing land ownership in the
proposed project area. Historically the federal
government owned all the land in the area as "public
domain". Large areas of federal land have been trans-
ferred to Alaskan Natives and the State of Alaska. A
6-95
6.5.3.2
small amount of state land was subsequently transfered to
the Kenai Peninsula Borough. Land ownership patterns
have not been finalized in the area. The largest
unresolved matter involves the settlement of land claims
associated with the Alaska Native Claims Settlement Act
(ANCSA) of 1971. Extensive federal and state lands have
been selected by the Natives but not all the legal
transfers have been completed. Native landowners include
Cook Inlet Region, Inc., Tyonek Native Corporation and
the Native Village of Tyonek.
A number of small parcels have been patented to
individuals, primarily along the coast, by both the
federal and state governments. Numerous easements and
rights-of-way exist in the area, again primarily along
the coast.
Rights to various resources, including timber, petroleum
and coal, have been sold in the area by both the state
and the Natives. Resource development activities w~ll
continue to have a major impact on the area •.
Federal Land
Federal lands in the area have been involved in
complicated proceedings due to often times overlapping
selections by the state and Alaska Natives and the
establishment of the boundaries of Lake Clark National
Park. Native selections on federal lands in the area
have been unofficially relinquished (CIRI, personal
communication, November 10, 1981). State selections are
still in force and are being processed. Thus, the state
may eventually gain patent to sorne of these lands. All
6-96
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federal lands outside of the park are administered by the
Bureau of Land Management. Federal land in the park is
administered by the National Park Service.
Bureau of Land Management
Federal lands administered by BLM include the Lake
Chakachamna power site and a number of townships
surrounding the power site. In 1947 lands in the
immediate vicinity of Lake Chakachamna system were
witharawn as a power site under Power Site Classification
395 (USS 3970). The power site includes all public lands
lying within one-quarter mile of Chakachamna Lake,
Kenibuna Lake, and the Chakachatna River from the outlet
at the lake to the mouth of Straight Creek •
The renaining BLM land, sorne of which is unsurveyed, is
being passively managed. Most of these townships have
been selected by the state. Native selections have also
been made on sorne townships but these selections are to·
be officially relinquished in the near future (personal
communication, CIRI, November 10, 1981). Until official
relinquishment is made BLM cannot act on the state
selections. Townships or portions of townships selected
by the state in the area but not selected by the Natives,
are on the state's ~riority list and may be conveyed in
the near future.
Lake Clark National Park
The park is administered by the National Park Service.
Lake Clark National Park and Preserve were established on
December 2, 1980 by the Alaska National Interest Lands
Conservation Act. This act provided for a national park
6-97
6.5.3.3
of approximately 2,439,000 acres and a national preserve
containing approximately 1,214,000 acres. The federally
owned or controlled lands of the park and preserve, by
virtue of their becoming part of the National Park
System, are subject to title 16 of the United States Code
and title 36 of the Code of Federal Regulations.
Management of all areas of the National Park System
follow the administrative policies setting forth broad
guidelines for park managers.
The portion of the park bordering the study area
including the Chilligan Rive~, Lake Kenibuna and its
tributaries is designated as wilderness.
Use of the park is discussed in the recreation section of
this report.
State Land f
Land in the proposed project area has been conveyed to
the State of Alaska by the 1953 Submerged Lands Act, the
1956 Mental Health Enablin~ Act and the 1958 Alaska
Statehood Act. State lands have been classified
according to the system described below.
The State Land Classification System which is currently
being revised is similar to zoning, in that there are
different classification categories which reflect the
capabilities and different potential uses of the land.
Unlike zoning, however, the classification system applies
to State-owned land only. Also unlike zoning, the
present state classification system contains no
provisions to guarantee that once title to State-owned
land is passed, it will continue to be used for the
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classified purpose. The classification system is
presently undergoing revision within the Division of
Lands. (State Division of Lands, CZM Report, December
31, 1977.
In the proposed project area the following land
classifications exist: Resource Management Lands and
Industrial Lands.
Resource Management Lands
Resource management lands contain an association of
surface and/or subsurface resources which are especially
suited to multiple use management.
In the proposed project area, resource management lands
are being used in several ways: oil and gas leasing, coal
prospecting and leasing, a timber sale and mining
permits, with sorne uses overlapping.
Industrial Lands
Industrial lands are those which, because of location,
\
physical features or adjacent developments, may best be
utilized for industrial purposes. According to the State
Administrative Code, these lands may be disposed of by
lease or sale (11 AAC 52 070) •
There are currently several sites of varying sizes which
are classified as industrial sites. These include the
Kodiak Lumber docking facility at North Forelands and
ether sites operated by Texaco and Atlantic Richfield.
See Table 6.13 for list of industrial sites.
6-99
6.5.3.4
Lands leased from the State for commercial or industrial
purposes can only be used for the purposes designated and
are subject to local building and zoning codes, which
involves the Kenai Peninsula Borough.
Native Land
There are four main classes of Native land ownership in
the proposed project area as a result of special
legislation:
o Cook Inlet Region, Inc. (CIRI)
o Tyonek Native Corporation (TNC)
o Native village of Tyonek
o Native Allotments
Other Native holdings or land ownership in the area
include patented parcels and set net sites.
Cook Inlet Region, Inc.
Unlike most areas of the state, selection of land
entitlements by CIRI was complicated by prier selection
of traditional village lands by the State of Alaska under
its Statehood Act entitlement. The lack of appropriate
land for Native selection led to litigation and
establishment of the Cook Inlet Land Exchange.
Under the land exchange, CIRI is to obtain patent to the
surface and subsurface estate of approximately 1.23
million acres of land. In addition, it receives
subsurface estate to another 1.15 million acres of land,
6-100
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Table 6.13. Industrial Sites.
Site
Number
C 170
C 1313
C 1336
C 1369
C 1483
C 1487
C 1906
Township Location and
Size
T . lIN., R. 12W., S . M .
Sec. 28, 255 B7 ac.
T.IIN., R.12W. , S.M.
Sec. 27, 248.64 ac.
T.IIN. , R.12W. , S.M.
Sec. 28, 351.45 ac.
T.IIN., R.12W., S.M.
Sec. 28, 126 ac.
T.IIN., R.12W., S.M.
Sec. 29. 397 ac.,
& Sec. 30, 6 ac.
Description
Tidelands
o & G Support
Facilities
o & G Support
Facilities
Date
Classified
12-13-61
9-30-65
12-27-65
o & G Support Facilities 4-13-66
(tidelands)
o & G Support 2-21-68
Facilities
T.IIN., R.12W., S.M. Ship Docking Facility 2-6-68
Sec. 28 & 33, 36.82 ac 0 & G Support
Facilities (tidelands)
T.IIN., R.IIW., S.M.
ATS 931, 44.86 ac.
Ship Docking Facility
Kodiak Lumber
Company
5-28-74
Source: State of Alaska, Department of Natural Resources Status
Plats. For complete legal descriptions, including aliquot
part descriptions, contact Alaska Division of Lands.
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the surface of whiGh is either patented to the village
corporations or is within the Kenai National Moose Range •
Village Corporations Associated with CIRI
Within the geographie boundqries of the Cook Inlet
Region, Inc., which extend from Seldovia in the south,
almost to Mt. McKinley in the north, there are six
village corporations: Chickaloon, Eklutna, Knik (Called
Knikatnu by the villagers), Ninilchik, Seldovia and
Tyonek. The acreage received by the Village Corporations
' is based on the number of stockholders who traced their
heritage back to a village and enrolled to a village
corporation. Approximately 6,000 Eskimos, Indians, and
Aleuts have enrolled to Cook Inlet Region, making it the
fifth largest Native regional corporation.
Under the conditions of the land exchange, six land
selection pools were established. By far the largest,
the Beluga Pool at 311,040 acres was made available to
CIRI by the State of Alaska. Cook Inlet Region, Inc.
has selected all of the lands in the Beluga Pool and
expects convenyance of all except T.l4N, R.lSW. The
northern half of that township covering the central part
of Capps Glacier was not state land and should not have
been set aside initially in the State's Beluga Pool.
Because the Beluga Gas Field subsurface and the Nikolai
Gas Field subsurface were both excluded in the exchange
agreement, Cook Inlet Region expects to receive only the
surface estate to the affected land located in T.l2 and
13N, R.lOW. (Beluga Gas Field) and T.llN, R.l2W.
{Nikolai Gas Field). Land selected by the Kenai
Peninsula Borough in T.l2N, R.lOW are available to CIRI
6-102
--------------------------------------------------------------------------------------------------------------------------------------------------------------i','
for the subsurface only. The surface estate will go to
the borough. Inasmuch as there is more subsurface estate
?Vailable to CIRI from the Boroughs' lands than there is
surface available, due to the gas fields' exclusion,
there is an imbalance in CIRI's selections.
In an effort to select their full entitlement of 311,040
acres, CIRI has selected somewhat more surface than
subsurface in T.l6N, R.l4W., The above lands are
considered the first priority for selection. These
selections exclude Beluga Lake and Lower Beluga Lake, and
the section of the Beluga River running between the
lakes. They also exclude U.S. Survey 3970, which
protects Power Site Classification 395 (April 22, 1948}
for potential hydroelectric development at Chakachamna
Lake and Chakachatna River.
Conveyance of the Beluga Pool Land to CIRI was subject to
any lawful reservations of rights or conditions contained
in the State conveyance as provided by the Terms nnd
Conditions document. Within two years aft~r initial
conveyance, the Secretary of Interior is authorized to
identify and reserve any easement he could have lawfulfy
reserved before conveyance. All valid existing rights to
coal prospecting permits, coal leases, oil and gas
leases, mineral leases, etc. are protected under terms of
the exchange.
The attitude of Cook Inlet Regi~n, Inc. toward
rights-of-way across their lands, is quite different than
that of Tyonek Native Corporation. While the Tyonek
Native Corporation has been opposed to all rights-of-way
and easements, CIRI is willing to consider them. They
recognize that in order to remove the natural resources,
such as coal, easements must be made available.
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Tyonek Native Corporation
One of the six CIRI village corporations, the Tyonek
Native Corporation was organized as a result of the
passage of the Alaska Native Claims Settlement Act by
Congress and represents the 303 Native people enrolled to
the village of Tyonek. The Tyonek Village entitlement
according to Section 14(a) of ANCSA is 115,200 acres-
substantially larger than the 69,120 acres most villages
receive. The size of Tyonek's entitlement is based on
the fairly large Native population which the village had
on the 1970 census enumeration date. Villages with a
population between 200 and 399 were entitled to 115,200
acres.
The lands patented to Tyonek Native Corporation will be
limited to just the surface estate of the lands -in
accordance with Section 14{a) and (b) of ANCSA. Patent
to the subsurface estate will be made to Cook Inlet
Region, Inc. according to Section l4(f} of ANCSA.
A stipulation of the regiona~ corporation patent to the
subsurface estate is that the right to explore, develop
or remove minerals from the subsurface estate in the
lands within the boundary of Tyonek Village, are subject
to the consent of the Village. Essentially this
provision gives Tyonek a "veto power" over unwanted
development by Cook Inlet Region.
Because there are not sufficient lands available for
selection to meet the village entitlement from among
lands surrounding the village, the Secretary of Interior
set aside "deficiency lands" from nearby unreserved,
vacant and unappropriated public lands. Thus, much of the
6-104
Tyonek Village's land selected under ANCSA is not
adjacent to the village site. Adjacent selectable lands
consisted of the Moquawkie Indian Reservation (the Tyonek
Village Indian Reserve) and State tentatively approved
lands. Several miles across Cook Inlet from the village,
lands within the Kenai National Moose Range were also
selected.
Deficiency selections were made south of the village
along the West Coast of Cook Inlet and from lands in the
upper Susitna River area, where the Susitna Hydroelectric
Project is planned.
Tyonek Native Corporation has leased land to Kodiak
Lumber Mills, Inc. for the lumber camp, chip mill, and
access roads and to various petroleum companies for
access roads. •
Native Village of Tyonek, Inc.
Tyonek, which is located on the former Moquawkie Indian
Reserve is not incorporated as a city under the laws of
the State of Alaska. However, it is a Federally chart-
ered Native village, governed by an IRA (Indian Reorgan-
ization Act) Tribal Council. The Tribal Council --also
called the Village Council --is the political arro of
Tyonek and which, prior to December 18, 1971 (the date
ANCSA was enacted) controlled the lands within the former
Moquawkie Indian Reserve under a trust relationship with
the u.s. Department of Interior, Bureau of Indian
Affairs. On December 18, 1971, this Reserve was
abolished by Section 19 of ANCSA, and the lands came
under the jurisdiction of the u.s. Department of
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Interior, Bureau of Land Management. The Tyonek Native
Corporation succeeded to the rights of the surface estate
of the Reserve under terms of ANCSA that had been enjoyed
by the Village Council. Because the Village of Tyonek
was located on the Moquawkie Indian Reservation, Section
19(b) of ANCSA came into play. This section of the
Settlement Act provides for an election of its members to
decide whether to retain the Indian Reserve and receive
the surface and subsurface estate to the reserve or to
opt for benefits of ANCSA. Tyonek Native Corporation
voted for the provi~ions of ANCSA. Had they taken the
former reserve, the village would have received fee
simple title (both surface and subsurface estates) to
26,918.56 acres of land compared to the 115,200 acres of
surface lands they are to receive under their ANCSA
entitlement.
The Village Council may own lands under reconveyance
provisions of Section 14(c) of ANCSA. The Village
Council has been considering incorporation as a city
under the laws of the State of Alaska. One reason stems
fiom an interest in retaining control of village lands
and lands destined for village expansion. Under ANCSA,
it is necessary for the village corporation, the Tyonek
Native Corporation, to convey. "the remaining improved
land on which the Native Village is located and as much
additional land as is necessary for community expansion,
an appropriate righ~s-of-way for public use, and land for
other foreseeable community needs" to the appropriate
municipal corporation where one exists or otherwise to
the State in trust for any municipal corporation
èstablished in the Native Village in the future. The
amount of land to be transferred to the municipal
corporation or in trust shall be no less than 1,280
6-106
acres, an area equivalent to two (2) square miles. Tyonek
Native Corporation will be receiving title to the lands
for the future city. If Tyonek were an incorporated city
under State law, Tyonek Native Corporation would reconvey
title to the City (their own tribal members) rather than
to the State to be held in trust for them.
The Tyonek Airfield is one of several private airfields
in the area. The field is maintained by the Village
Council and has been found to be a costly public
improvement. At one time, the Village Council attempted
to transfer the airfield to the State in an effort to
ease their financial burden. At that time, the offer to
give the airfield to the State was not accepted. The
Village Council has retained the right to refuse landing
privileges to unwelcome aircraft. The village residents
prefer to have control over who visits their community
and because of their outright ownership of the airfield
they have had sorne control. However, the villagers do
not like the costs associated with ownership.
The surface estate of the existing Tyonek airport, airway
beacons, and other navigational aids, together with such
additional acreage and/or easements as are necessary to
provide related services and to insure safe approaches to
the. airport runways must be reconveyed to the Federal,
State or Municipal government according to the require-
ments in Section 14 (c) (4@ of ANCSA.
Native Allotments
The Native Allotment Act of May 17, 1906, as amended
August 2. 1956, authorized the Secretary of Interior to
allot land to any Indian, Aleut, or Eskimo of full or
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mixed blood who resides in and is a Native of Alaska and
who is the head of a family or is 21 years of age. A
land area not to exceed 160 acres of vacant,
unappropriated and unreserved non-mineral land in Alaska,
or subject to the provisions of the Act of March 8, 1922,
certain vacant, unappropri.ated and unreserved public land
in Alaska that may be valuable for coal, ail or gas
deposits or under certain conditions of National Forest
Lands in Alaska was made available if various conditions
were, met.
The title to a Native Allotment is under a restricted
title; the land cannat be mortgaged, leased, sold, or
deeded away without the approval of the Secretary of
Interior or someone designated by him. The allotee or
his heirs may deed the allotted land to another with the
approval of the Secretary of Interior and the purchaser
will then receive an unrestricted or fee simple title
unless the purchaser is a Native whom the Secretary of
Interior determines should continue to have a restricted
title.
There are six Native Allotments in the proposed project
area. Two have been patented, and four are still in the
application stage and have not been fully adjudicated by
the Bureau of Land Management; see Table 6'.1·4.
Private Land
Five private patented land holdings (U.S. Surveys) are
located in the project area and shawn in Figure 6.27.
Privately held leases are discussed in the following land
use sections. Many of the parcels of lands that have
6-108
been transferred to the state and Natives in the area
have ROW reservations. Approximately 29 ROW permits and
applications are on file with Alaska DNR.
Easements Across Native Lands
One of the thorniest issues of land rights in the
proposed project area has been that of easements across
Native lands. The Tyonek Native Corporation has
adamantly refused to accept any easements across their
former Moquawkie Indian Reserve and has also taken a very
strong position relative to easements across lands they
have selected north of the reservation {Division of
Energy and Power Development). However the Interim
Conveyance, I.C. 087, to their former Moquawkie Indian
Reserve, contains several easements, at least temporarily
set aside by the federal government.
Easement On and To the Marine Coastline
Interim conveyance documents cite a cont~nuous 25-foot
wide linear easement along the coastline for purposes of
public access and recreation. The Department of Int~rior
has suggested reducing the continuous easement to site
easements along the coast at appropriate points to
facilitate travel purposes only, such as beaching of
water craft. A limited number of linear access easements
perpendicular to the coast would be reserved to allow
access to interior public lands.
Easements On and To Waterways (Rivers, Lakes and Streams)
The present federal policy of reserving easements along
recreational rivers and streams is restricted to periodic
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points along "major" waterways. Major waterways are to
be defined by the criteria of significant commercial or
transportation use, or significant resource value
(including recreation). The use of these site easements
will be limited to activities related to travel along the
waterway (e.g beaching of beats and float planes). Sorne
linea= access easements to "major" waterways and to
public lands beyond conveyed Nat:ive lands may be reserved.
Transportation and Utility Corridors and Statutory
Basements
Interim Conveyances retain rights-of-way for ditches,
canals, telephone and telegraph lines and railroads
constructed by the authority of the federal government.
Easement corridors for energy, fuel, and natur&l
resources transportation were also reserved and included
the right of eminent domain. These easements must be
justifiable, and site specifie at the time of conveyance.
Section Line Easements
Section line easements of 33 feet on each side of the
section line for a total of 66 feet provide legal access
to federal lands. State lands have a 50-foot section
line easement, 50 feet on each side of the section line.
Although section line easements do not provide access
that relates to the topography, they do provide legal
access across the land.
An important question regarding the existing right-of-way
between section lines is the possible and potential usage
of the land for purposes ether than highways, or in
conjunction with highways. Alaska Statutes 19.25.010
6-110
6.5.3.5
provid~s the legal authority and required approvals for
the use of utilities along the constructed highways
rights-of-way. There is presently considerable
overlapping of authority of the rights-of-way. The
Department of Transportation and Public Facilities and
the Division of Lands, are currently establishing
regulations which will disentangle the overlapping
authority, clarify accepted uses and revise procedural
materials.
Land Use
The major land uses are shawn in Figure 6.28.
Timber Harvesting
On August 22, 1973, the state sold the timber rights on
223,000 acres to Kodiak Lumber Mills, Inc. (Kk~). Much
of the timber had been damaged by spruce beetle infest-
ation and is only useful for salvage. The quantity of
timber involved in the sale is estimated to be 6 million
board feet. KLM's 30 million dollar chip mill, camp, and
pier are located 5 miles south of Tyonek on land leased
from the Tyonek Native Corporation. A network of logging
roads has been constructed to gain access to the timber.
The majority of workers are transients who are housed in
the camp. From time to time, 5-15 villagers work for the
company. The current slump in the chip market has led to
a reduction in shipping activities during 1981.
6-111
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Table 6.14. Native allotments in shoreline townships.
Application No.
AA 6459
AA 7268
AA 7324
AA 7788
A 055082
A 055680
Location and
Size
T.l2N., R.llW., S.M.
M & B, 160 ac.
T.l2N., R.llW., S.M.
160 ac.
T.l2N., R.llW., S.M.
160 ac.
T.l2N., R.llW., S.M.
16à ac.
Certificate No.
and Date
Apln 8-23-71
Apln 3-20-72
Apln 3-23-72
Apln 4-20-72
Date
Occupied
1949
7/1946
5/1953
6/1957
T.l2N., R.llW., S.M. 50-75-0138/3-14-75 11-16-40
u.s.s. 4547, 119.39 ac.
T.l2N , R.llW., S.M.
u.s.s. 4546, 160 ac.
50-66-0608/6-20-66 9-15-41
Source: BLM Status Plats, June 1978. For complete descriptions,
including aliquot part descriptions, contact Alaska Division
of Lands.
6-112
The current timber leases expire in 1983. The state is
considering leasing more land for additional salvage
purposes. If Kodiak Lumber Mills is the successful
bidder, another 5-6 years of work could be anticipated.
Petroleum
Interest has been shown in the area's oil and gas
resources since the late 1950's. There have been several
state, federal, and private lease sales, both on and
offshore, since the mid-1960's. Extensive seismic
testing and test drilling has been and continues to be
conducted on many of the leases. Several gas fields have
been discovered onshore and both oil and gas fields have
been discovered offshore. Information on each of these
fields is presented in Table 6.15.
Other than pipelines there are two petroleum-related
facilities on the west side of Cook Inlet in the vicinity
of the proposed project. Marathon Oil Company has an oil
and gas treatment plant 20 miles southwest of Tyonek on
Trading Bay. The ether facility is the Drift River
Petroleum Terminal, which is described in the trans-
portation section of this report.
The most recenc State lease sale in the area, Number 33,
held on May 13, 1981, received strong interest (Anchorage
Daily News, May 15, 1981 p. A-3). Two State lease sales
are now scheduled or proposed that will probably include
tracts on or near the proposed project's area. They are
listed in Table 6.16.
6-113
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Table 6.15. Oil and Gas Fields in the Project Area.
Field
1. West Fore1and
2. Middle Ground
Shoal (MGS)
3. North Cook Inlet
4. Beluga River
5. North MGS
6. Trading Bay
7. Granite Point
8. McArthur River
9. Moquawkie
10. Nicolai Creek
11. Ivan River
12. Albert Kaloa
13. Redoubt Shoal
Type
Gas
Oil
Gas
Gas
Gas
Oil
Oil
Oil & Gas
Gas
Gas
Gas
Gas
Oil
Location
On shore
Offshore
Offshore
Onshore
Offshore
Offshore
Offshore
Offshore
On shore
On shore
On shore
Onshore
Offshore
Date of
Discovery Well
ApriT 1962
June 1962
September 1962
December 1962
November 1964
June 1965
June 1965
October 1965
November 1965
May 1966
October 1966
January 1968
September 1968
Source: Situations arid Prospects Kerial--Peninsula Borough 1981.
6-114
~able 6.16. State Oil and Gas Lease Sales
Number
40
49
Sale Area
Second Upper Cook
Cook Inlet
Proposed Date
9/83
5/86
Comment
Scheduled
Proposed
Source: State of Alaska Current Five-year Oil and Gas Leasing
Schedule -DNR revised 8/31/81 and DNR-DMEM Call for
Comment.s 81.
Oil and Gas Leases
The Department of Natural Resources, through the Division
of Minerals and Energy Management, is authorized to lease
subsurface oil and gas resources on a competitive and
noncompetitive basis. All lands in the public domain are
open for oil and/or gas exploration and development. The
provisions o~ the Miscellaneous Land Use Permit apply to
surface oil and gas related activity on state lands where
no lease has been issued. In addition, the state, under
provisions of the Alaska Land Act, reserves rights to all
subsurface gas and oil resources on lands disposed for
any other purpose.
Federal leasing in the area has all taken place on
offstore tracts, further south, in lower Cook Inlet.
Coal
Both coal prospecting permits and coal leases are
available on State lands.
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Table 6-17. Coal Leaseholdings.
Company Acreage
Placer Amex Inc. 25,926
(Beluga Coal Company)
Diamond-Chuitna 20,571
(Diamond Alaska Co )
Mobil Oil 23,080
AMAX, Inc. 3,880
(Meadowlark Farms)
Employees
Construction -?
Operation -500
Contruction -2000
Operation -800
N/A
N/A
Startup
Date
1987
(30 years)
1987
N/A
N/A
Source: Tyonek Community Profile (Draft) Ralph Darbyshire and
Associates, September 1981.
,1
6-116
Table 6.18. Locations where Subsistence Occurs.
Polly Creek The beaches in this area are used for clamming
in the spring.
Redoubt Bay The beaches in this area are used heavily and
have been relied upon for many years for clams.
Use occurs in both spring and fall, but spring
use is especially important after winter food
supplies have been depleted and before the
spring salmon run begins. The beaches south of
Drift River Terminal to Harriet Point are used
most extensively.
Trading Bay and
McArthur River
a. Drift River: Historically, the upper and
middle reaches were used most heavily for
hunting and trapping. Today, sorne duck and
seal hunting is pursued in the lower reaches.
b. Kustatan River: The entire vicinity is
hunted heavily when the McArthur River area
and other areas do not have many moose.
Sorne trapping takes place here.
Upper McArthur River areas are·used for moose
hunting
and furbearer trapping. McArthur Flats is used
for waterfowl hunting and furbearer trapping.
a. Middle River and lower area flats are used
for moose hunting, trapping and waterfowl
hunting.
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Chakachatna River
Noaukta Slough
Chuitkilnacha Creek
and associated
marsh areas
Granite Point to
Chuitna River
Chuitna River and
Chuit Creek Area
Beluga Flats and
Lower reaches of
Beluga River
Used for moose hunting, trapping, and waterfowl
hunting.
Used for duck hunting.
The "shoreline areas here are relied upon for
subsistence and commercial salmon and herring
fishing. This is the main fishing area for
Tyonek residents.
Both are used extensively in winter months for
trapping and moose hunting.
a.
b.
Chuitbuna Lake referred to as Chuit Lake)
area is used for trapping and hunting
especially in the viin•ter. Dur ing the fall
the area around this lake is used for berry
picking. This area has a particular
importance because of its proximity to
Tyonek village.
The areas west and north of Beluga village
are used very heavily in fall for hunting
moose and in winter for furbearer trapping.
This is also an important berry picking area.
c. Old TYOnek Creek and the lakes area around
Congahbuna Lake are used for moose hunting
and trapping.
These locations are very important for hunting
whale and waterfowl. Sorne seals are also taken
here.
6-118
Susitna River The mouth and lower reaches are used for beluga
whale a~d seal hunting in the spring and fall.
Source: A Social, Economie and Environmental Analysis of a State
Oil and Gas Lease Sale in Upper Cook Inlet; Governor•s
Agency Advisory Committee on Leasing, 1981.
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Coal Prospecting Permits
A coal prospecting permit allows the permittee to
determine the existence or workability of coal deposits
in an unclaimed and undeveloped area. The permit is
valid for two years and each permit may include up to
5,120 acres. If within the period of two years, the
permittee shows that the land contains coal in commercial
quantities and submits a satisfactory mining plan for
coal rerovery, the permittee can obtain a lease. A coal
prospecting permit may be extended for a period of two
years if the permittee can provide adequate reasons
(regulated by the Department of Natural Resources) .
Coal Leases
Coal leases run for an undetermined period of time,
conditional upon the continued development and/or
operation of a mine. Coal lease contracts can be
assignable, upon the approval of the Director of the
Division of Lands, by the lessee subject_to the laws and
regulations applicable to the lease.
There are three major coal lease areas in the vicinity of
the proposed project: the Capps lease area, the Chuitna
Lease area and the Three Mile lease area. Table 6.17
indicates the number of worke~s expected in each project
and an expected start-up date.
A coal-to-methanol plant has been proposed in the area
but with recent federal budget cuts the probability of
the plant being financed solely by private money at this
time is uncertain.
6-120
Most of the coal in the area is planned to be open-pit
mined but the methods for transporting the coal to
tidewater have not yet been determined.
Mining Claims
There has been sorne interest shown in the mineral
resources, other than coal, on state lands in the
proposed project area. Many of these claims were filed
quite recently. A large block of mining claims is
located along the Upper McArthur River.
Subsistence
Subsistence activities of the villagers are described in
the Socioeconomics section of this report. The
discussion in this section focuses on the location of
these activities. Subsistence activities of the
villagers occur both on Tyonek Native Corporation land
and on adjacent coastal areas. Subsistence use areas are
identified in Table 6.18. The general area of greatest
use extends from the village south to the Polly Creek
area and north along the coast to the mouth of the
Susitna River. The use an area receives is dependent
both upon access and the availability of resources. For
example, coastal areas, river banks, and areas along the
road system where boats and vehicles can be used to
transport hunters and game are used more extensively than
areas only accessible by foot. The use of areas within
the general subsistence harvest area may also vary from
year to year depending upon the availability of
subsistence resources.
6-121
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6 5.4
Subsistance users of resources, other than Tyonek
residents, may also be in the area of interest. Of the
160U subsistance permits for salmon issued for upper Cook
Inlet in 1979, 62 permits were used in the area from the
Susitna River to West Forelands (A. p. 67).
Shore Fishery Lease --Set Net Sites
Possibly as little as ten percent of the fishermen using
set nets along the coast have obtained shore fisheries
leases. Normally leases are obtained only when encroach-
ment is threatened by other fishermen. Although shore
fishery leases protect the fishing site from the
encroachment of other fishermen~ leases do not protect
the shore fishery lease holder from other uses, such as a
dock. Although apparently not required by state law, it
is suggested that set net fishermen with shore fishery
leases and fishermen without leases be reimbursed for the
loss of livelihood, once that loss has been established,
or anothei site of equal productivity satisfactory to the
fishermen be sought as a replacement. The State of
Alaska, Department of Fish and Game can identify any
affected set net fishermen in the ar~a, all of whom must
also have Limited Entry Permits to fish in the Inlet.
Recreation
While the project area under consideration is remote and
sparsely populated, considerable recreational use is made
of it. Recreational use is concentrated toward the coast
but is increasing on Chakachamna Lake and tributaries
feeding into the lake.
6-122
6.5.4.1
Water related recreation occurs most frequently along the
coast where the Chakachamna and McArthur Rivers empty
into Trading Bay. Recreational use of the Trading Bay
State Game Refuge is somewhat quantified and is discussed
in the following subsection.
Recreation activities have been increasing in the
vicinity of Chakachamna Lake, primarily fly-in hunting,
fishing, hiking, and kayaking. Future promotion and use
of Lake Clark National Park could increase use of
Chakachamna Lake.
Trading Bay State Game Refuge
The 168,930 acre Trading Bay State Game Refuge (TBSGR)
was created in 1976 for the protection of waterfowl and
big game habitat. The refuge includes uplands, tidal and
submerged lands. Public access is by small aircraft,
both wheel and float equipped, and less commonly by boat.
A series of shallow brackish marshes, encompassing
approximately 2500 acres, runs the length of Trading Bay.
These marshes support vast numbers of migrating ducks,
geese, swans, and shorebirds in both spring and fall, as
well as providing nesting for a substantial number of
dabbling ducks. Nesting geese are unknown in this area,
although nesting occurs to the north at Susitna Flats and
to the south at Redoubt Bay.
The Trading Bay Refuge is the ninth most important
waterfowl hunting area in the state. In 1978 there were
735 hunting days of effort expended in the refuge, 1.1
percent of the state waterfowl hunting total.
(Seller, 1979)
6-123
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6.5.4.2
Coastal areas of western Cook Inlet, which includes the
Trading Bay Refuge, are considered critical calving and
overwintering moose habitat. The latest harvest figures
indicate that a number of moose were taken in this area
in 1980.
Nikolai Creek receives limited fishing pressure. The
creek contains rainbow trout, Dolly Varden, and pink and
silver salmon.
A number of cabins (2 on private land, 13 on state land)
have be~n built within the refuge by waterfowl hunters.
In June, 1978, ADF&G announced a moratorium on new cabin
construction on state game refuges. Although ADNR was
given authority to issue permits for cabins on state land
within Trading Bay Refuge, no permits have been issued to
date. The Shirleyville lodge caters to recreationists in
the area and several air charte! businesses provide
access to the refuge.
Chakachatna/McArthur Rivers
Recreational use of the upper stretches of the
Chakachatna and McArthur Rivers is less well known. The
rapids in the upper reaches of the Chakachatna are quite
difficult but they are thought to be navigable (DNR
Division-of Parks, personal communication). Thus kayak
trips from a starting point in Lake Chakachamna are a
possibility but this potential use is undetermined.
6-124
6.5.4.3
6.5.4.4
6.5.5
Chakachamna Lake
Lake Clark National Park rangers report the use of the
western end of Lake Chakachamna as a staging area for
recreational use (personal communication). Gravel bars
on the east end of the lake and other gravel bars at the
river deltas are used to unload visitors from float and
wheeled planes both air taxi and privately owned
(personal communication, Hartell). People kayak on the
lake and hike by the lake and up the many drainages such
as the Chilligan River. One of these routes goes west
toward Lake Kenibuna and leads into Lake Clark National
Park.
Lake Clark National Park
The eastern boundary of Lake Clark National Park crosses
Kenibuna Lake. This portion of the park is classified as
wilderness, and is considered by the park supervisor to
be the heart of the park (personal communication
Hartell). No formal recreation facilities have been
planned for this ar~a, nor are any use statistics
available.
Socioeconomics
The proposed project is located in an isolated and
sparsely populated area within the Kenai Peninsula
Borough. Tyonek, a Native village, is the only community
in the vicinity of the project area. The proposed
Chakachamna Hydroelectric project has the potential to
create population, employment, income, infrastructure and
subsistence impacts in the Tyonek area. Because it has
the responsibility ~or providing government services the
Kenai Peninsula Borough (KPB) will be the principal
impacted local government entity. Due to the small
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6.5.5.1
Year
Population
population of Tyonek, employmen1: impacts will pr imar :lly
occur on the Kenai Peninsula and in the greater Anchorage
area. For each impact area (Tyonek, KPB and Anchorage),
baseline socioeconomic information is presented •
Tyonek
The Native village, Tyonek, is located on the western
shore of Cook Inlet, 42 miles east of Lake Chakachamna
and 22 miles northeast of where the Chakachatna River
enters Cook Inlet.
Population
The census figures for Tyonek are reported below:
1880 1890 1900 1910 1920 1930 1940 1950 1960 1870 1980
117 115 107 N/A 58 78 136 132 187 232 239
Source: o.s. Census
6-126
The recent Tyonek population has seen periods of relative
stability broken by significant increases in population.
The 1980 census has not been officially completed, but
the population appears tc have stabilized since 1970.
The 1970 census indicated that 95% of the population was
Native with 127 males and 105 femalese Median ages were
16.6 and 18.6 years for males and females, respectively.
Non-Native residents are, for the most part, teachers who
remain in the village for one tc several years.
Employment
In many respects Tyonek is a traditional Alaskan Native
village. Commercial fishing is the primary source of
earned cash incarne. In addition tc the lirnited number of
service jobs available within the village, work is also
obtained with the nearby timber operation and
occasionally with petroleurn exploration activities in the
area. Like many Native villages, a heavy reliance is
placed on subsistence resources. The following indicates
the employrnent status of a sample of Tyonek's popùlation.
6-127
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EMPLOYMENT BREAKDOWN BY PERCENT OF HOUSEHOLD RESPONSE
No. of Members
in Household
0
1
2
3
4
5
6
7
Full time
Percent
55
38
7
Part-Time/
Seasonal
38
54
8
Retired
91
9
Unemployed
26
16
26
16
10
3
3
Source: Report on the Survey Conducted in Tyonek, 1980 ADF&G,
Alice Stickney, Subsistence Section, Anchorage.
6-128
Commercial fishing (limited entry) permits are held by 27
residents. A permit holder may employ up to six people
as crew. The fishing season is usually open only 2 days
a week from July 1 to August 15. Salmon are the target
species with most of the permits for set gill nets and a
few for drift gil~ nets. Commercial catches tend to be
low and profitability is further hampered by the lack of
a processor or cannery in the vicinity. Fish are either
flown out, pot scows utilized or a tender cooperatively
hired. Most fishermen use little if any of their catch
for subsistence needs, opting rather for cash sales to
pay expenses.
The majority of workers employed by the Kodiak Lumber
Mills'operation near Tyonek are transients who are housed
in the camp. Employment of villagers varies from 5-15
workers throughout the year (Kodiak Lumber Mills, Inc.
personal communication). Due to a variety of
lifestyle/personal conflicts, full advantage of
\
employment opportunities in the timber operation have not
been taken by residents of the Tyonek Village (Braund and
Behnke 1980) •
Occassionally work with petroleum exploration firms is
available on a temporary basis.
Permanent employment opportunities in the village are
limited to the following positions: teachers and school
support staff -20, village administration -6, firemen -
3, store retailers -2, day care center employees -2,
and one each of the following: constable, community
health aide, community health representative, post-
mistress, air taxi operator, and emergency responder with
the fire department. CETA funded 3 full time positions
(superviser of youth employment, laborer and recreation
6-129
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worker) as well as 16 summer positions for youth in 1981.
(Darbyshire and Assac. 1981). With the recent federal
budget cuts the future of the CETA positions is
uncertain.
Personal Incarne
The cash flow through the village economy is low. A
profile of incarnes obtained through a 40 household survey
is shawn below.
INCOME BREAKDOWN BY PERCENT OF HOUSEHOLD RESPONSE
Total Incarne Percent of Percent of Commercial Percent of Other
Dollars Households Fishery Households Households
c
0-3000 13 0 20
3-6000 30 16 45
6-10,000 30 47 15
10-15,000 12 21 5
15-20,000 5 5 5
20-30,000 10 11 10
Source: Report on the Survey Conducted in Tyonek, 1980, Alice
Stickney, Subsistence Section, ADF&G, Anchorage.
Over 70 percent of all the responding households earned
less than $10,000 in gross annual incarne. Thirty percent
of these were commercial fishermen who made up 63 percent
of the total responding commercial fishermen. The type
of aid, coming into the village was also limited. Fifty-
6-130
five percent of the responding households had only
Native/Public Health benefits, while the other 45 percent
had additional aid in the form of Social Security,
disability, unemployment checks, ADFC and food stamps.
Subsistence
Subsistence, the traditional hunting/fishing/gathering of
local resources, is important to Tyonek residents for
several reasons. The traditional pursuit of subsistence
is interwoven into village social structure and sharing
among residents. Because of this, and village preference
for local food, subsistence resources cannot be equated
in terms of market goods. Additionally, the limited job
and income opportunities in Tyonek place great importance
on subsistence as a means o~ providing food.
Subsistence patterns vary with the season and abundance
of particular species. Although fish and game
regulations have modified traditional patteEns, local
residents continue to follow a cycle resembling that of
their ancestors. aesidents of Tyonek fish, hunt, trap,
dig clams, and pick berries. Four wheel drive vehicles,
snow machines and outboard motors are used in subsistence
pursuits.
King salmon comprise one of the important subsistence
species. During the 1980 season 67 subsistence fishing
permit holders harvested 1936 king salmon and 262
incidental red salmon. Each permit had a limit of 50
king salmon and the maximum season harvest for the
community was set at 3000 kings. Sixty-five percent of
the allowed harvest was reached.
6-131
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6.5.5.2
Moose, ducks, geese, and spruce hens are hunted in season
while porcupine are hunted year-round. A few village
residents set traps for marten, mink, red fox, and
beaver. Euchalon, rainbow trout, Dolly Varden and
whitefish also provide a source of food for many
residents. Residents of the community also hunt beluga
whales and seals. Blueberries, raspberries, high and low
bush cranberries, and salmonberries ripen in the late
summer and early autumn and are primarily gathered by
women in the village.
Kenai Peninsula Borough
The proposed project is located within the Kenai
Peninsula Borough. Most of the population of the Borough
is located on the western half of the Kenai Peninsula,
across Cook Inlet from the proposed project. The Kenai
Peninsula will be a source of labor and materials for the
proposed project.
Population
The population of the Borough is 25,072, up 51.2 percent
from 1970 (U.S. Census 1980). The Kenai census division
which encompasses the western half of the Kenai Peninsula
has a population of 22,271.
Employment
The labor force as of August, 1981, contained 12,300
workers, 9.8 of whom were unemployed. (Alaska Department
of Labor 1981). Both the labor force and the unemploy-
ment rates exhibit marked seasonal variations. The
following table (Table 6-19) indicates employment and
wages by industry for the Kenai-Cook Inlet Division.
6-132
6.5.5.3
The Kenai Peninsula is likely to be a significant source
of labor for the proposed projec~. Employment impacts
are not quantifiable at this point in the feasibility
study.
Personal income impacts while not quantifiable at this
time are likely to be minimal. The unemployment rate may
drop somewhat and thus reduce the amount of unemployment
insurance payments.
Anchorage
Alaska's largest city, Anchorage is located approximately
60 miles east of the proposed project area. Anchorage is
likely to serve as a major supply center for both labor
and materials.
The Anchorage area is likely to be the major source of
in-state labor for the proposed project but the
employment i~pacts are not quantifiable at this time.
Many of the area's construction workers are available for
out of town work. The extent of their availability will
depend on the status of other construction projects in
the state such as the North Slope, Susitna dam, etc.
Population
The Municipality of Anchorage has a population of 173,992
as of 1980, up 37.7 percent from 1970 (U.S. Census 1980).
Employment
As of August, 1981, the Municipality had a labor force of
91,671 persons with 6.9 percent unemployment (Alaska
Economie Trends, October 1981, Department of Labor, State
of Alaska). Table 6-20 indicates employment and wages by
industry.
6-133
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Table 6.19. Kenai-Cook Inlet Division Area Nonagricultural
Employment and Payroll Industry Series -Alaska. 3rd
Quarter 1980.
Industry Average No. of Employees Average Monthly Wage
Mining 793 3,085
Construction 902 3,531
Manufacturing 2022 1,581
Transportation,
Communication and
Utilities 671 3,142
Wholesale Trade 272 2,515
Retail Trade . 1048 1,021
Finance, Insurance
and Real Estate 203 1,259
Services 1023 1,366
Agriculture, For estry
and Fisheries 51 2,387
Government 1169 1,981
Unc1assifiable 1131 1,158
Totals 8185 2,055
Source: Statistical Quarterly -3rd Quarter, 1980. Department
of Labor, State of Alaska.
6-134
($)
6.5.6
6.5.6.1
6.5.6.2
Community Infrastructure
Housing
There are 89 homes in Tyonek, almost all Ôf which are
owned by the Tyonek Village IRA Council. Approximately
60 prefabricated homes were barged to and erected in
Tyonek in the mid-1960's. These homes, as well as 6
trailers, (2 of which are owned by the KPB school
district for teacher housing), form the housing stock of
the older part of the village. Outbuildings such as
smokehouses and steambaths are situated in this portion
of town.
An additional 27 wood-frame homes were built in 1978-79
through the joint efforts of the Department of Housing
and Urban Development and Cook Inlet Native Association.
These homes are located west of the airstrip in Indian
Creek subdivision or the "new subdivision" as it is
referred to by the townspeople.
All the transient employees of Kodiak Lumber Mills, Inc.
are housed in the company camp south of Tyonek. The camp
can accommodate up to 200 people. The camp has six
20-person bunkhouses, five 3-bedroom modular homes, about
12 trailers and six duplexes. The Shirleyville Lodge is
located adjacent to the Nickelai Creek airstrip. The
lodge includes trailers and cabins that can accommodate
24 people. Meals are also available.
Education
Bob Bartlett School serves grades K through 12 and is
financed and managed by the Kenai Peninsula Borough
School District. Located in the Village of Tyonek, it is
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the only school serving the area. The school has four
regular classrooms, a home-economies suite, and a
portable classroom, for a total capacity of 240 students.
Enrollment history and school district projections are
presented below. The total 1976-1977 enrollment was 108,
with 75 in grades K-8, and 33 in grades 9-12. As of May
1978, 98 students were enrolled~and 7 teachers (5 regular
and 2 cultural resource teachers) were employed. The
Borough's 1977 school-construction report indicates that
no facilities other than a new home-economies suite need
to be provided during the 5-year period ending in 1982.
When the Kodiak Lumber Mills' mill was in full operation,
approximately 20 children were bussed from the camp to
the village to attend the school.
PUPIL ENROLLMENT AND PROJECTIONS, BOB BARTLETT SCHOOL, TYONEK
School Year K-8 9-12 Total
1972-73 76 21 97
1873-74 65 22 87
1974-75 73 18 91
1975-76 87 28 115
1976-77 75 33 108
1977-78 82 34 116
1978-79 90 34 124
1979-80 95 37 132
1980-81 103 38 141
1981-82 llO 41 151
Source: Kenai Peninsula Borough School District, Enrollment
Projections and School Construction Report, April 1977 ..
6-136
Table 6.20. Anchorage Division Area Nonagricultural Employment
and Payroll Industry Series -Alaska. 3rd Quarter
1980.
Industry
Mining
Construction
Manufacturing
Transportation, Communi-
cation and Utilities
Wholesale Trade
Retail Trade
Finance, Insurance and
Real Estate
Services
Agriculture, Forestry and
Fisheries
Government
Unclassifiable
TOTALS
Average
No. of Employees
2,915
7,190
2,532
8,318
4,230
13,324
4,900
17,182
197
20,356
607
81,751
Average
Monthly Wage ($)
3,286
3,252
2,636
2,264
2,150
1,171
1,649
1,125
1,019
2,061
1,522
1,958
Source: Statistical Quarterly -3rd Quarter, 1980. Department
of Labor, State of Alaska.
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6.5.6.4
Police Services
Police services in the Tyonek area are provided by the
Alaska State Troopers through a resident constable. The
constable serves the area from the Beluga power station
south to Trading Bay, including the cil and gas
facilities at Trading Bay and Granite Point and the
lumber mill camp near Tyonek. A four-wheel drive vehicle
is used by the constable to patrol the area and an
airplane is available to fly the area if the need arises.
The constable at Tyonek has the time and ability to
handle an additional number of complaints and ether
police activity, but the point at which population
increases will require the state troopers to add another
policemen is difficult to estirnate.
In a work-camp situation, the troopers encourage private
companies to hire their own staff for internal security.
The troopers are then available to provide emergency
assistance. The temporary assignment of additional
troopers to the area is another option, especially if
camp activity is short-term or seasonal. In the proposed
project area, this would involve assigning staff from the
Soldotna regional office of the state troopers.
Fire Protection
Publicly provided fire protection services are currently
available in Tyonek through the U s. Department of
Interior, Bureau of Land Management.
6-138
6.5.6.5 _ Health Care and Emergency Medical Services
6.5.6.6
The state troopers are responsible for supervising rescue
operations for emergency situations in the proposed
project area. Medical evacuations are usually
accomplished by private charter plane. The u.s. Air
Force also handles sorne emergency evacuations.
Health care services are available to the residents of
Tyonek through a medical center located in the village.
The facility handles bath medical and dental work and is
staffed by a resident, licensed practical nurse. The
clinic also has a community health aide (and alternate)
provided through the U S Public Health Service. The
health aide may provide services ta non-Natives on an
emergency basis only. Non-Natives are billed for the
service. Emergency medical care is received at the ANS
hospital in Anchorage.
The Kenai Borough's Central Hospital service area
encompasses over 1000 square miles of land on bath the
east and west side of Cook Inlet. On the west side of
Cook Inlet, the service area extends from Beluga River ta
Drift River, including the study area. A 32-bed hospital
is located at Soldotna.
Water and Wastewater Systems
The existing water source for the village of Tyonek is a
nearby lake. The former ground water supply was
abandoned because of its high iron content (with
manganese). The water system, which includes an
infiltration gallery and pump house, was installed by the
Village in 1976. The lake water is chlorinated, stored
6-139
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in a tank, and filtered with activated carbon before
being delivered to the underground distribution system,
which was completed in 1972 under an EDA contract. A
previous groundwater well was developed in 1964 by the U
S. Public Health Service, but is used only for public
water supply. Each house and the school is served by the
distribution system. The 27 new housing units planned
for the village by Cook Inlet Housing Authority will be
connected to the distribution system.
The primary method of wastewater disposal at the village
of Tyonek is by septic tanks with subsurface leach
fields; some cesspools are also used. The septic tanks
were installed in 1965, have a capacity of 200 to 400
gallons, and are constructed of low-grade steel. Some of
the tanks are rusting. The soils have a gravel base,
making them good for subsurface disposal. The problems
.that have developed with the onsite systems are probably
a result of the small size of the tanks and inadequate
maintenance. An unfenced sanitary landfill is located
4.2 miles from the village. The Kenai Peninsula Borough
is in the process of establishing a new landfill for the
village, but it may be some time before all approvals are
obtained
Water for the Kodiak Lumber Mills Camp is supplied from
three wells, which have been adequate to support 200
people to date; no water shortages have occurred. The
water contains an excessive amount of iron and barely
meets water quality standards. However, no bacteria
problems exist. Water is distributed through an
underground system that requires standard maintenance.
No winter freezing problems have been encountered.
6-140
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Septic tanks with perforated-pipe drainfields are used
for waste disposal. The systems have required normal
maintenance: no special problems have developed. The
soils (consisting of a gravel base, covered with a few
feet of sandy loam and sorne clay) are good for subsurface
disposa! •
Water for Trading Bay is supplied from wells at Marathon
Oil Company's Trading Bay facility and no shortages have
occurred. Septic tanks with drain fields have also been
used with very few problems.
Transportation
Transportation facilities on the west side of Cook Inlet
are few and small in aize. These facilities consist of
logging and petroleum exploration roads, several
airfields, a wood chip loading pier and a petroleum
loading dock. The numerous reôource development
potentials in the area may eventually lead to an
expansion of facilities •
Roads
All roads in the area of the project are shown in Figure
6. 29. Most of the road system in the proposed proje<:t
area has been developed by Kodiak Lumber Mills in the
form of logging roads. The road system connects Granite
Point, Tyonek, Nicolai Creek, Kaloa, North Foreland, and
Beluga. There are about lOO milee of primary and
secondary roads. These roads are in good condition,
especially the main roads. Sorne of the bridges on the
6-141
secondary roads have washed out and have not been
replaced. The main logging road extends approximately 16
miles northwest of Congahbuna Lake to within 8 miles of
Capps Coal Field. Most roads are sand, overlain with
gravel, and require no special maintenance. The roads are
resurfaced following breakup.
Road rights-of-way (lOO feet wide) are established along
the section lines of all state land (or land acquired
from the state). All other land has a 66-foot right-of-
way along section lines. Sorne legal questions have been
raised about how this right-of-way provision applies to
land "reserved for public use." No rights-of-way are
associated with the network of logging roads. Access was
permitted as part of the state's timber sale contract
with Kodiak Lumber Mills.
The Beluga area, north of Tyonek, and Anchorage are not
connected by a year-round road; however, a winter road
has been used in the past when the Susitna River was
frozen. The road was originally constructed to carry
large, heavy equipment to the area, but it has not been
used since the mid-1970's.
The Alaska Department of Transportation and Public
Facilities has studied the Beluga area and developed
plans for river crossings and roadways. A proposed
highway would run from Tyonek to Goose Bay (about 65
miles), crossing the Susitna and Beluga Rivers. Existing
roads already connect Goose Bay to Knik (10 miles), Knik
to Wasilla (19 miles), and Wasilla to Anchorage (47
miles) •
6-142
-
The proposed highway is not likely to be constructed in
the near future, primarily because the economic benefits
to be derived from it do not justify the co@struction
costs. The proposed highway may become more attractive as
additional projects for resource and industrial
development in the Beluga area (aluminum smelter, coal
generating plants, etc.) are proposed or become feasible.
Two historic trails, identified in Table 6.21, in the
area were identified in a 1973 inventory done by the
State Department of Highways (now the State Department of
Transportation and Public Facilities). The Highway
Department claims legal access through prescriptive
rights along these traditionally travelled ways.
6-143
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Table 6.21. Historie Trails.
Trail
Name
Susitna -
Tyonek
Winter Trail
Quandrangle
& Number
Q70 -#2
Q70 -#3
( 1 {
Location
T.ll, 12, 13, 14,
15, 16, 17N. R.7,
8, 9, 10, llW. SM
T.llN.R.l2, 13W, SM
r . f (
Source
ARC Annual Report
1930 Part II, Page
61. & Fifty Years
of Highways -AK
Dept. Public Works,
Div. of Highways
1960, pg. 29-30.
USGS Tyonek Quad
( 1
Description
Trail begins at town
of Susitna T.l7N.
R.7W. and runs in a
SW direction for 46
miles to town of
Tyonek T.llN.RllW.
Trail runs from Trad-
ing Bay to cabins on
Nikolai Creek.
Source~ State of Alaska. Department of Highways. Alaska Existing Trail system. 1973.
Table 6.22. Airport faci1ity characteristics.
Name Owner Class LenS!th Surface Comments
Tyonek Pvt. Utility 3350' x 100' Gravel
1427' x lOO' ....il
Beluga Pvt. Non CAB 3500' x 110' Gravel Lighted
Non CAB 5000" x llO' Gravel Lighted
Nikolai Creek Pvt. Non CAB 4100' x 75' Grave1
Trading Bay Pvt. Non CAB 4500' x 100' Graval-Lighted
dirt
West Fore1and Pvt. Utility 1975' Dirt
(Unit No. 2)
Drift River Pvt. Non CAB 4300' x 150' Gravel Lighted
40' Graval
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6.5.7.3
Air
The larger air facilities within the vicinity of the
project are identified in Table 6-22. The airport in
Tyonek is operated by the Native Village of Tyonek.
Planes as large as DC-6's and Hercules can be
accommodated. Pilots must obtain permission from the
Village before landing. The FAA estimates that there are
approximately 2000 annual air taxi landings at Tyonek.
Air taxi operators serving Tyonek include Trading Bay Air
Taxi, Spernak Airways, Wilbur's Flight Operations, Hudson
Air Taxi, Gil's Aircraft Service, and Alyeska Air
Service, Kenai Air, Kenai Aviation, and Arctic Aviation.
Other airstrips in the area include a poorly maintained
3500-foot City Services Oil Co. field, 8 to 10 miles west
of Beluga; a 1700-foot airstrip in good condition at
North Foreland that will handle a Sky Van; and several
light aircraft strips, including two 900-foot strips at
Capps Field.
All airfields in the Tyonek-Beluga area are privately
owned and maintained. Use of the airstrips requires
permission of the owners.
Marine
A private wood chip loading pier owned by Kodiak Lumber
Mills is located 3 miles south of Tyonek. The pier is
260 feet long with 685 ·feet of berthing space and a depth
alongside of 35 feet at mean low water. The dock would
need to extend about 3700 feet from shore to reach a 60
foot depth. The dock is used from April to November
depending on shipping schedules. The largest ship to
dock here was 607 feet long and 45,000 metric tons •
During 1980 only six freighters were loaded from the pier
and with the decline in the chip market even fewer will
6-·146
6.5.8
dock in all of 1981. Recently, a test shipment of coal
was loaded from the pier onto a freighter headed for
Japan.
A special purpose petroleum dock owned by Cook Inlet
Pipeline co. and operated by Mobil Oil is located at
Drift Rivér, 47 miles southwest of Tyonek. The terminal
at Drift River was built in 1966 and is used solely to
load tankers with crude oil which is transferred. to Drift
River via pipelines from offshore wells in Cook Inlet.
The dock is lOO feet long with a 100 foot face and depth
alongside is 70 foot. There is 780 feet of berthing
space with breasting and mooring dolphins. The dock can
accommodate 150,000 dead weight ton tankers {medium size).
There is also a barge off-loading ramp, owned by Standard
Oil, located 4 miles southwest of the Beluga River.
Tyonek and the Tyonek Lumber Mills' camp bath receive
supplies by barge which are off-loaded on the beach.
Visual Resources
The project area falls into three categories of landform
characteristics: steep rnountainous terrain, vegetated
uplands and coastal wetlands. Chakacharnna Lake,
Chakachatna River Canyon, and the headwaters of the
McArthur River are located in narrow glaciated valleys
surrounded by steep, rugged mountains. Scenic quality is
high, particularly on Chakachamna Lake and the
Chakachatna River. The lake allows a long view where
hanging glaciers drop to lake level, and tributaries to
the lake forrn syrnrnetrical deltas. The Chakachatna River
exits the lake into a canyon surrounded by steep
6-147
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mountains. At this point the river alternates between
single channel and braided systems, and has relatively
continuous whitewater. Because of its scenic quality,
Chakachamna Lake was originally considered for inclusion
as national interest lands under Section 17(d)-2 of the
Alaskan Native Claims Settlement Act of 1971. The
braided floodplain of the upper McArthur River is 3/4 of
a mile wide, and is roughly 50 percent vegetated with
contrasting exposed sandbars. Because of the twisting
nature of the canyon, the length of viewshed is
relatively short. Vegetation on the steep lower slopes
of the lake and beth drainages consists of a thick
mixture of conifers and deciduous birch and alders, above
which lies a band of shrub thicket, and alpine
vegetation. This vegetation provides a contrast to beth
the lake and river ~looaplains.
Upon leaving the mountains both the Chakachatna and
McArthur Rivers enter well-vegetated uplands. Here the
broader river valleys fluctuate between braided and
single channels. The dense vegetation of cottonwood,
whi~e spruce and willow limits views from the rivers dnd
screens out the backdrop of mountains. Two relatively
unusual visual areas are located within the upland
landform. An expanse of dry sand flats is found along
the middle reach of the McArthur River. This dune-like
area provides visual relief (texture and color) from the
dense vegetation, and allows longer vistas of the
surrounding mountains. A border of lichencovered flats
further contributes to the aesthetics of this area.
Similar, but smaller, areas of lichen flats are located
along the Chakachatna River at the logging road bridge.
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6-148
The vegetated uplands gradually give way to open wetlands
along both rivers. These coastal wetlands extend inland
roughly five miles from the coast. The low vegetation of
grasses and sedges and open water allows long vistas of
the surrounding mountains, Cook Inlet, and the Kenai
Peninsula across the Inlet. The primary river form in
these wetlands are meandering single channels with steep
mud banks. Tidal influence extends four or more miles
upchannel in sorne instances. These coastal wetlands
provide excellent waterfowl habitat, and have relatively
high visiter use compared to other portions of the
project area.
6-149
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REFERENCES
Hydrology
Lamke, R.D. 1979. Flood characteristics of Alaskan
streams. u.s. Geological Survey Water Resources
Investigations 78-129. 66 pp.
Tennant, D.L. 1975. Instream flow regimes for fish,
wildlife, recreation and related environmental
resources, u.s. Fish and Wildlife Services, Billings,
Montana.
Aquatic Biology
~laska Dept. of Fish and Game. Undated. Fish Survey
Reports of Lower Cook Inlet.
Bailey, J.E. 1964. Intertidal spawning of pink and chum
salmon at Olsen Bay, Prince William Sound, Alaska.
Manuscript Report MR 64-6. USFWS. Bureau of
Commercial Fisheties. Biological Laboratory. Auke
Bay, Alaska.
Bailey, J.E. 1969. Alaska's Fishery Resources: The pink
salmon. Fishery 1eaflet 619. USFWS. Bureau of
Commercial Fisheries. Washington, D.C.
Balon, E.K. (Ed.) 1980. Charrs, salmonid fishes of the
genus salvelinus. Dr. W. Junk by Publishers. The
Hague, The Netherlands.
Baxter, R. and s. Baxter. 1961. Stream surveys-west side
Cook In1et-1961, ADF&G. Cook Inlet Data Report. 61-1.
6-150
Bell, M.C. 1973. Fisheries handbook of engineering
requirements and biological criteria.
Fisheries-Engineering Research Program, Corps of
Engineers, North Pacifie Division. Portland, Oregon.
Blackett, R.F •• 1968. Spawning behavior, fecundity, and
early life history of anadromous Dolly Varden,
salvelinus malma (Walbaum) in Southeastern Alaska.
Research Report No. 6. Alaska Dept. Fish and Game,
Juneau, Alaska.
Blahm, T.H., R.J. McConnel and G.R. Snyder. 1975. Effect
of gas supersaturated Columbia riverwater on the
survival of juvenile chinook and coho salmon. NOAA
Technical Report SSRF-688. National Marine Fisheries
Service, Seattle, WA.
Burns, J.W. 1970. Spawning bed sedimentation studies in
northern California streams. California Fish and
Game, 56(4): 253-270.
Committee on Environmental Effects of the United States
Committee on Large Dams. 1978. Environmental effects
of large dams. American Society of Civil Engineers,
New York, N.Y.
Fickeisen, D.H. and M.J. Schneider (Ed). 1976. Gas
bubble disease. Technical Information Center, Office
of Public Affairs Energy Research and Development
Administration, Oakridge, TN.
Forester, R.E. The sockeye salmon. Oncorhyncus nerka.
Bulletin 162. Fisheries Research Board of Canada.
Ottawa, Canada.,
6-151
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~-
-
-
"-
.,.,..
-
-
',_
.,_
Garner, J. 1977. How to make and set nets. Fishing News
Books LTD. London, VIC.
Hart, J.L. 1973. Pacifie fishes of Canada. Bulletin
180. Fisheries Research Board of Canada. Ottawa,
Canada.
Hasler, A.D. 1971. Orientation and fish migration in
s.w. hoar and D.J. Randall {Editors). Fish
Physiology, Volume VI, Environmental Relation and
Behaviors, Academie Press, NY.
Krcma, R.F., c.w. Long, c.s. Thompson, W.E. Farr, T.W.
Newcomb, and M.H. Gessel. 1979. The development of an
improved fingerline protection system for lowhead
dams-1978, National Marine Fisheries Service, Seattle,
WA.
Kubik, c.w. 1981. Memorandum: king salmon data. ADF&G
unpublished.
Leggett, J.W. 1980. Reproductive ecology and behavior of
Dolly Varden charr in British Columbia. IN E.K. Balen
(Editer) Charrs, Salmonid Fishes of the Genus
Salvenlinus.
Martin, N.V. and C.H. Olver. 1980. The lake carr,
salvelinus namaycush in E.K. Balon Charrs, Salmonid
Fishes of the genus Salvenlinus.
McConnel, R.J. and G.R. Snyder. 1972. Key to field
identification of anadromous juvenile salmonids i.n the
Pacifie northwest. NOAA Technical Report NMFS
CIRC-366. us Dept. of Commerce Seattle, WA.
6-152
Merrell, T.R., Jr., M.D. Collins, and J.W. Greenough.
1971. An estimate of mortality of chinook salmon in
the Columbia River near Bonneville Dam during the
summer run of 1955. Fishery Bulletin 68(3): 461-492.
Merrell, T.R., Jr. 1970. Alaska's fishery resources the
chum salmon. Fishery leaflet 632. USFWS. Bureau of
Commercial Fisheries. Washington, D.C.
Morrow, J.E. 1980. The freshwater fishes of Alaska.
Alaska Northwest Publishing Company. Anchorage,
Alaska.
Nelson, D.C. 1976. Russian river red salmon study.
Study AFS-44-2. ADF&G. Sport Fish Division,
Anchorage, Alaska.
Nikolski, G.V. 1961. Special ichthyology. 2nd Edition.
Isreal Program for Scientific Translations, National
Technical Information Service, Springfield, VA.
Oglesby, R.T., Carlson, C.A., McCann, J.A. (ed) 1972.
River ecology and man. Academie Press, NY.
Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A.
Lachner, R.N. Lea, and W.B. Scott. 1980. A list of
common and scientific names of fishes from the United
States and Canada. Fourth edition. American
Fisheries Society, Special Publication No. 12 American
Fisheries Society. Bethesda, MD.
Russell, R. 1978.
Chakachamna.
Unpublished.
Lake survey summary, Lake
Alaska Department of Fish and Game.
6-153
~
' ' -~
.....
.. -
.....
._
b..
......
-
-
-
......
,._.
-
-
-
-.. 1~,.,.,.._....., .... -""N?""-00" ____ _
Scott, W.B. and E.J. Crossman. 1973. Freshwater fishes
of Canada. Bulletin 84. Fisheries Research Board of
Canada. Ottawa, Canada.
•
Shaw, P.A. and J.A. Maga. 1943. The effect of mining
silt on yield o-f fry from salmon spawning beds.
California Fish and Game. 29(1): 29-41.
Smith-Root, Inc. 1978. A brief introduction to
electrofishing. Smith-Root, Inc. Vancouver, WA.
Smoker, W.A. (Editer}. 1955. Preliminary key for
identification of salmon fryf juveniles, and adult.
State of Washington, Dept. of Fisheries •
Tennant, D.L. Instream flow regimes for fish, wildl:ife,
recreation and related environmental resources •
USFWS. Billings, Montana.
Troutman, M.B. 1972. A guide ta the collection and
identification of presmolt pacifie salmon in Alaska
wi th an illustrated key. , NOAA Technical Memorandum
NMFS ABFL-2. u.s. Dept. of Commerce. Seattle, WA •
von Brandt, A. 1972. Fish catching methods of the
world. Fishing News (Books) Ltd.· London, u.w.
Wydoski, R.S. and R.R. Whitney. 1979. Inland fishes of
Washington. University of Washington Press. Seattle,
WA.
u.s. Bureau of Reclamation. 1960. Chakachatna River and
Chakachamna Lake, Alaska. 2 sheets. u.s. Geological
Survey, Washington, D.C.
6-154
Ward, J.V. and Stanford, J.A. (Ed) 1979. The ecology of
regulated streams. Plenum Press, New York.
Wells, R.A., and W.J. McNeil. 1970. Effect of quality of
the spawning bed on growth and development of pink
salmon embryos and alevins. USFWS Special Scientific
Report-Fisheries i616, u.s. Fish and Wildlife Service,
Washington, D.C.
Wildlife Biology
Pfister, R.D., B.L. Kovalchik, S.F. Arno, and R.C.
Presby. 1977. Forest habitat types of Montana.
Intermountain Forest and Range Experiment Station,
USDA Forest Service.
Sellers, R. 1979. Waterbird use of and management
considerations for Cook Inlet State Game Refuges.
Alaska Departme~t of Fish and Game. Unpublished
report.
Timm, D. and R. Sellers. 1981. Annual report of survey
1
and inventory activities-waterfowl. Project progress
report on federal aid in wildlife restoration, project
job number 10.0, volume 12.
Human Resources
Alaska Department of Labor, 1980. Statistical Quarterly,
3rd Quarter.
Alaska Department of Labor, September 1981. Alaska
Economie Trends {monthly) •
6-155
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-
-
-
-
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-
...
-
-
-·
-
"'-
-
Braund, S.R. and Associates. 1980. Lower Cook Inlet,
petroleum development scenerios, Socio Cultural
Systems Analysis-Technical Report Number 47,
Socioeconomic Studies Program.
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Tyonek {draft) Anchorage, Ala.ska unpublished report.
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Regional Energy Resources Planning Project, Phase 2 -
Coal Hydroelectric and Energy Alternatives, Vol. 1 -
Beluga Coal District Analysis, for Dept. of Energy.
Governor • s Agency Advisory Commit tee on Leasing. 1981. A
social, economie analysis of a State oil and gas lease
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Sellers, R. 1979. Waterbird use of and management
qonsiderations for Cook Inlet State Game Refuges.
Alaska Department of Idsh and Game. Unpublished
report •
l
Stickney, a. 1980. Report on the survey conducted in
Tyonek. Subsistence Sectionp Alaska Department of
Fish and Game, Anchorage, Alaska.
6-156
EVALUATION OF
AL TER NATIVES
7.0
7.1
7.1.1
-
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EVALUATION OF ALTERNATIVES
Engineering Evaluation
General
The figures quoted in this section of the report for the
estimated cost of energy are considered to be
conservative for two basic reasot1s as set forth below.
The first reason is the conservative approach taken to
calculate the amount of energy that could be generated by
each of the four alternatives. In the power studies, the
maximum lake level was taken as elevation 1128 whicn had
been reported as the approximate invert elevation of the
lake outlet channel. The natural maximum lake water
level is reported to have been at about elevation 1151.5
and the records show that the lake rose to that level or
within about
taken in the
would accrue
be available
1128. The re
5-feet of it each year. No credit has been
calculations for any additional energy that
from the higher heads that would temporarily
when the lake water level exceeded elevation
is also the possibility that once diversion
of water for power generation begins, the outlet channel
may choke and its invert may rise above its present
elevation thus creating a higher head for power
generation. If the maximum water level is taken, as
elevation 1142, the installed capacity for Alternative s
would increase from 330 MW to 350 MW and the average
annual energy would rise by 6% from 1446 GWh to 1533 GWh.
The second reason is that the approach to estimating the
cost of constructing each of the alternatives is
considered to have been realistic.. Analyses have been
7-1
7.1.2
7.1.3
made of bids received for projects involving similar
types of construction and the unit priees used in the
estimates are consistent with those that have been
receivej in recent competitive bidding in cases where the
analyses have permitted such comparisons to be drawn.
Furthermore, although the estimates make allowances for
certain lengths of the tunnels where production may slip
and costs may increase due to adverse rock conditions, an
overall 20% contingency allowance over and above the
estimated cost of construction, engineering and
construction management has been included in arriving at
the estimated total project costs.
Chakachatna Dam
On the basis of what was seen in surface exposures during
reconnaisances of the Chakachatna Valley, little
encouragement could be found for pursuing a course based
on the concept of siting a dam anywhere in the valley
between the lake outlet and the mouth of the canyon.
Although the possibility has not been completely ruled
out, it is considered most unlikely that justification
for siting a dam here could be confirmed.
Alternative A
This alternative, which would take all controlled water
from Chakachamna Lake for the generation of electrical
power in a powerplant located in the McArthur Valley, is
the most advantageous identified by the present studies
when regarded strictly from the point of view of power
generation. As may be seen by reference to Table 7-1,
the powerplant would have the maximum installed capacity
(400 MW), and would yield the maximum average annual firm
7-2
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energy (1664 GWh) at the lowest unit cost (37.5 mills per
kWh). It is considered that these figures can safely be
regarded as conservative for the reasons set forth in
Section 7.1.1 acove.
Although sorne modification and refinement of the basic
elements of the development, as they are presently shown
on the drawings, will probably become desirable during
the course of optimization studies to be performed in
1982, it is technically feasible to design and construct
all features of a project following the concept of
Alternative A.
Alternative B
This alternative follows the same basic layout as that
for Alternative A, but approximately 19% of the average
annual flow of water into Chakachamna Lake, during the
period of outflow gauge records, would be reserved for
release into the Chakachamna River near the lake outlet,
to satisfy the tentative minimum instream flow require-
ments discussed in Section 7.3.2 of this report. This
would cause the installed capacity to be reduced from
400 MW to 330 MW. The average annual firm energy would
reduce 1374 GWh at a unit rate of 43.5 mills/kWh. This
is 16% higher in cost than for Alternative A but is still
significantly less than the 55.6 mills/kWh which is the •
estimated cost of energy from the most competitive
thermal source, a coal fired plant, as discussed in
Section 9.4 of this report. .~lternative B bas the
advantage that instream flows are provided in the
Chakachamna River for support of its fishery and based on
the tentative amount of water reserved for these instream
flow requirements the project would still be an
economically viable source of energy.
7-3
7.1.5
The same comments set forth above in Section 7.1.3
regarding feasibility of designing and constructing
Alternative A apply equally to the structures for
Alternative B except that a design concept has not yet
been identified for a fish passage facility that would
maintain a means of entry into and exit from Chakachamna
Lake for migrating fish. This will be included in the
1982 studies.
Alternatives C and D
Both of these alternatives would divert water from
Chakachamna Lake to a powerplant located near the
downstream end of the Chakachamna Valley. For
Alternative c, alL controlled water would be used for
power generation. For Alternative D, water required to
meet the instream flow releases discussed in Section
7.3.3 of the report would not be available for power
generation. This water amounts to 30 cubic feet per
second average annually, which is less than l% of the
total water supply. Being that small, it can be ignored
at the present level of study.
As may be seen from Table 7-1, the installed capacity for
both Alternatives C and D would be 300 MW. The average
annual firm energy would be 1314 GWh at 52.5 mills/kWh
for Alternative C and 54.5 mills/kWh for Alternative D.
The installed capacity and energy that would be generated
by Alterntatives C and D are significantly less than in
the case of both Alternatives A and B, and the cost of
energy is significantly higher. Alternatives C and D are
inferior in comparison with Alternatives A and B as
sources of hydro power. At 55.6 mills/kWh, energy from a
coal fired plant would be only marginally more expensive
7-4
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tnan the energy that could be generated by irnplernenting
Alternatives C or D. It would thus appear that these two
alternatives could be dropped JErorn further consideration.
7-5
TABLE 7-1
COST OF ENERGY
Alternative
Installed capacity-MW
Annual generation-GWh
Deduct 5% for transmission
losses and station service-GWh
Firm annual energy-GWh
Capital cost including IDC
at 3% -$Billions (1)
Annual cost 3.99% including
interest, amortization and
insurance for 50-year
project life -$Millions
Net cost of energy -Mills/kWh
O&M -M ills/kWh
Total cost of energy -Mills/kWh
A
400
1752
88
1664
1.5
59.9
36
1.5
37.5
(1) Excluding Owner's costs and escalation.
•
7-6
B
330
1446
72
1374
1.4 5
57.9
42
1.5
43.5
c
300
1314
66
1248
1.6
63.8
51
1.5
52.5
D
300
1314
66
1248
1.65
65.8
53
1.5
54.5
'W
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7.2
7.2.1
Geological Evaluation
ChaKachatna Dam
Although the canyon like topography along the Chakachatna
River about six miles downstream from Chakachamna Lake
might appear to be suitable sites for a dam, the geologie
characteristics of the canyon suggest that construction
of a dam there is unlikely to prove feasible, and if such
construction is attempted, it is likely to be very costly
and a complex engineering problem for the reasons
discussed below.
As discussed in Section 5.2.2, there is a marked
difference in the bedrock from one side of the
Chakachatna Canyon to the other. The south side of the
canyon consists of a steep wall of glaciated granite,
which appears to be well suited for a dam abutment. In
contrast, the north wall of the canyon exposes a complex
of geologie units dominated by lava flows, pyroclastics,
and volcaniclastics, but including outwash and fill. If
the ideas presented in Section 5.2.2.2 are basically
correct, the volcanics may overlie alluvium below the
present valley floor: both the volcanics and the alluvium
rest on granitic bedrock at an unknown depth below the
valley floor. In addition to specifie adverse foundation
conditions suggested by deposits found on the north
valley wall (e.g. high permeabilities, low strength), the
chaotic character of those deposits would make the
prediction of foundation conditions at a given site very
difficult.
7-7
7.2.2
Any impoundment in the Chakachatna Canyon will be subject
to the volcanic hazards associated with Mt. Spurr
(Section 5.2.2.2). The youthfulness of Mt. Spurr, as a
whole, and the fact that it has been active in historie
time suggest that continued eruptive activity should be
factored in as a design consideration for any facilities
in the Chakachatna Canyon.
Alternative A
On the basis of the observations made during the 1981
field program, it is possible to comment on several
geologie factors that may influence consideration of
Design Alternative A (and B); see also Sections 5.2.1.6,
5.2.2.3, 5.2.3.4, and 5.2.3.3.
(1) Although any lake tap site between the lake outlet
and First Point Glacier would be subject to impact
from a very large eruption of Mt. Spurr, no site in
that area is likely to be disturbed by Crater Peak
type events (Section 5.2.2.2).
(2) The bedrock characteristics pertinent to tunnelling
have not been specifically studied; this will be a
subject of study during 1982. General observations
in the Chakachatna Canyon, aerial observations of
snow-and-ice-free bed-rock exposures between the
Chakachatna and McArthur canyons, and general
observations in the McArthur Canyon suggest that
bedrock conditions are likely to be well suited to
tunnel construction, with the exception of the
lowermost portion of the canyon, near the Castle
Mountain fault. The Castle Mountain fault, which
bas bad Holocene activity along at least part of its
7-8
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length, is present near the mouth of the canyon and bas
apparently disrupted the bedrocK (shears, intense
jointing) in the lower reaches of the canyon. For any
project facilities constructed in the fault zone, there
would be a risk associated with fault rupture: large
ground motions would likely occur during an earthquake on
the fault. One of the design alternatives presented in
this report include facilities in the fault zone, as it
is now know. Additional work is planned for this area in
1982.
(3) Slope conditions above both the proposed lake tap
site and outlet portal site are generally similar in
that there is no evidence of large-scale slope
movements in the recent past and rockfall appears to
be the dominant slope process. Talus at the base of
the slope at the proposed outlet portal/powerhouse
site (Figures 3-1, 3-2) suggests a significant
amount of rockfall activity in post-glacial tirne.
(4) As discussed in Section 5.2.1.4, a significant
advance of Blockade Glacier could disrupt drainage
in and near the lower reaches of the McArthur
Canyon. There was no evidence identified during the
1981 field work to suggest that such an event is
likely in the near future.
Alternative B
The comments in Section 7.2.2 apply to this alternative,
also.
7-9
7.2.4 Alternatives C and D
On the basis of the observations made during the 1981
field program, it is possible to comment on several
geologie factors that may influence consideration of
Design Alternative C (and D); see also Sections 5.2.1.6,
5.2.2.3, 5.2.3.4, and 5.3.3.3.
(1) In this alternative, bath ends of the hydroelectric
system would be sugject to the volcanic hazards
associated with Mt. Spurr. Comment No. 1 for
Alternative A (Section 7.2.2) applies here, also.
Volcanically-induced flooding is judged to be the
volcanic hazard most likely to affect the outlet
portal/powerhouse site (Figure 3-3) in the
Chakachatna canyon.
(2) On the basis of general observations (i.e., not
observations specifically designed to assess
tunnelling conditions), the granitic rock types that
predominate in the area of the proposed tunnel
alignment (Figure 3-3) are generally well suited for
tunnelling. Local zones of intensive weathering,
alteration, or extensive jointing and shearing may
provide poor tunnelling conditions.
(3) The slopes above bath the lake tap and outlet portal
sites consist of glaciated granitic bedrock. No
evidence of large-scale slope failure was observed
during the 1981 reconnaissance field work. Rockfall
appears to be the dominant slope process.
7-10
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7.3
7.3.1
Environrnental Evaluation
The prelirninary environmental overviews presented in the
following sections for each project alternative are based
on data obtained from agency personnel, available
literature, and the lirnited information collected during
the 1981 fall reconnaissance programs. Although a
complete evaluation of all influences of each alternative
is not included in this section, anticipated major
environmental differences between alternatives are
presented. These differences should not be considered
definitive, and are only included at this time to
facilitate comparisons of the alternatives.
Chakachatna Dam Alternative
If a dam was constructed and operated on the Chakachatna
River, impacts would be inflicted on the anadromous
fish. Even if Chakachamna Lake and its tributary streams
remained accessible by fish ladders for upstrearn
migrants, lasses of downstream migrating fingerlings
would occur unless an effective method could be developed
to allow their safe passage past the dam. Due to the
water quality alterations in the river downstream from
the dam, the use of important fish migratory and spawning
habitat likely would be reduced. This, in turn, could
impact Cook Inlet commercial fishery resources.
If a large decline in the lake fishery occurred, wolves,
bears, and eagles would probably migrate to lower
elevations, thus increasing the density of animals in the
remaining forage areas. Other large mammals that
ordinarily utilize the Chakachatna River canyon for
migration to and from summer and winter range would
7-11
----------------------------------------------------------------------------------[~·
7.3.2
probably also be impacted. Since the canyon area
upstream from the dam would be flooded, a high quality
visual resource will be affected by the loss of the
white-water reach of the river. In addition, fluctuating
Chakachamna Lake water levels associated with all
alternatives will impact the scenic quality of the lake
shoreline. If the lake levels are raised so that the
tributary deltas are inundated, additional juvenile
rearing and spawning areas may be created for resident
lake fish, (primarily lake trout). However, although
fishing and hunting access to the lake by wheeled
airplanes would be reduced, access by float plane will be
unaffected.
Although the impacts from this alternative may be severe
in that a major fishery could be lost, many of the
impacts, including the damage to the aquatic resources,
potentially could be mitigated, primarily through the
installation of appropriate fish passage structures.
McArthur Tunnel Alternatives A and B
Through the implementation of Alternatives A or B, the
impacts resulting from construction and logistical
support activities would be very similar. Although the
major impacts will be inflicted on the fish and wildlife
of the area, the human resources will also be affected.
With increased access to the McArthur Canyon and
Chakachamna Lake, important visual resources as well as
fisheries and wildlife habitat may be degraded.
Once in operation, the increased flows in the McArthur
River may result in changes in water quality and
alternations in the chemical eues that direct anadromous
7-12
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fish to their spawning grounds. Although the possibility
also exists that the population of salmon will increase
in the McArthur River, predation may also increase. If
large mammals begin to concentrate in these high density
fish areas, sport and subsistence hunting pressure will
probably also increase.
The major difference in these alternatives is that in
Alternative A, no water would be provided in the upper
reaches of the Chakachatna River, while in Alternative B,
sorne flows would be maintained. Since this distinction
means the difference in whether the anadromous fish
population survives in the lake and the lake tributaries,
the difference in impacts is substantial. Again, impacts
on commercial fishing would be tied to direct changes in
anadromous fish populations.
In Alternative A, with a reduction in the lake fishery
due to the obstruction of migration pathways, and
resident fish spawning activities limited by fluctuations
in the lake level, the large mammals and eagles that
ordinarily make use of that resource as a food source
will probably migrate to lower elevations where the
density of wildlife will then probably increase. This
will have bath positive and negative effects on the human
resources. If the lake fishery were lest, commercial
fisheries in Cook Inlet may be impacted. However,
subsistence fishing will most likely not be affected
since there is currently very little use of this fishery
resource for subsistence. With increased access to the
area and perhaps increased numbers of large mammals,
sport and subsistence hunting success may improve. In
addition, increased access may open new areas to timber
harvesting, petroleum development, and mineral
exploration.
7-13
Alternative B would provide for year round flows in the
upper reaches of the Chakachatna canyon (Table 7.2). The
amount of instream flows selected are approximately 30
percent ~f the average annual flow during April through
September and between approximately 10 and 20 percent of
the average annual flow during the winter months, October
through March. These flow quantities are very tentative
and the final recommendations regarding flows to be
released to mitigate potential adverse impacts will be
based on further studies to be performed in 1982, and
then may be greater or less than the values presented
herein. Through the implementation of Alternative B
there should be little long-term impact on the fish and
wildlife of the Chakachamna drainage provided that fish
passage facilities are provided at the lake outlet to
permit upstream and downstream fish migrations. The
influence of the human resources will probably also be
less severe since the commercial fishery will probably
not be as heavily impacted.
While the impacts related to Alternative A affecting
local resources would be difficult to mitigate and
significant changes in both the distribution and
abundance of fish and wildlife populations would almost
certainly occur, the impacts resulting from Alternative B
would be less severe and relatively more amenable to
mitigative measures, again primarily through the
installation of fish passage structures.
It should be noted, however, that while not directly
stated, the loss of spawning areas, and juvenile habitat
due to any of the project alternatives will most likely
eventually manifest itself as a decline in the population
of adult fish as well. In addition since eggs, fry, and
7-14
-
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1
Table 7.2 Natural and Alternative B regulated mean monthly and mean
·annual flow at the ChaKachamna Lake outlet.
Mon th
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Annual
Flow
Natural
(cfs)
613
505
445
441
1,042
5,875
11,950
12,000
6,042
2,468
813
1,206
3,645
Regulated
(cfs)
365
343
345
536
1,094
1, 094
1,094
1,094
1,094
365
365
360
679
a Regulated flows were estimated using the Montana Method as
described in Section 6.2.2.1
7-15
7.3.3
juveniles of all species provide food {prey) for other
species, losses of spawning and nursery areas will almost
certainly result in eventual reductions in the standing
crop of their predators. For example, losses of juvenile
sockeye salmon in Chakachamna Lake would probably also
result in an overall decline in lake trout.
Chakachatna Tunnel Alternatives C and D
Through the implementation of Alternatives C or D, the
impacts resulting from logistical support or construction
activities would be similar. However, since all
activities are restricted to the Chakachatna flood-plain
in these alternatives, the resources in the McArthur
drainage will not be affected. Although impacts on the
wildlife populations may occur, significant impacts will
occur to the fisheries. Since access to Chakachamna Lake
'fillll)l'
~
will be increased, sport and subsistence fishing pressure ~
may increase. However, with the road, campsite and
disposa! site for rock excavated from the tunnel, all
located in the Chakachatna canyon, an important visual
resource will be modified. In addition the presence and
activity associated with these facilities may impede
large mammal movements through the canyon temporarily
during construction of the project.
During the pre-operational phases, the fishery in the
Chakachamna drainage will probably only be impacted to a
small extent over a relatively short term. Above the
powerhouse, the impact on the Chakachatna River and
Chakachamna Lake fishery will be dependent on whether
flows are maintained and fish passage facilities
provided. Alternative C does not allow for these
mitigative measures. Therefore, the impacts to the
7-16
~
-
lo!oii
·-
-
·-
-
-
-
-
....
-
,_
-
-
-
--------------------------------·~·'""""""""MJ.::a;l<~~·t; --'
Table 7. 3 Natural and Al ternat ive D regulat.ed mean monthly and mean
annual flows at the Chakachamna Lake outlet.
Mon th
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Annual
Flow
Natural
{cfs)
613
505
445
441
\1,042
5,875
11,950
12,000
6,042
2,468
1,206
1,206
·3,645
Regulated
(cfs)
30
30
30
30
30
30
30
30
30
30
30
30
30
a Regu1ated f1ows were assumed to be sufficient minimum f1ows to
maintain migratory passage as described in Section 6.2.2.1.
7-17
fishery at or above the lake, and thus the wildlife and
commercial fishery in the surrounding area will be
similar to that inflicted through Alternative A. Since
Alternative D does provide flows (Table 7.3} and
migratory passages, the impacts would be similar to those
described for Alternative B.
Within the project area, sorne resources will be affected
no matter which alternative is chosen. This is parti-
cularly true of scioeconomic, land use, and transport-
ation characteristics. Through the implementation of
mitigative measures, it may be possible to offset many of
the adverse impacts. However, the mitigation technniques
outlined will probably not restore the environment to
pre-operational condition.
7-18
...
...
wui
~
CONSTRUCTION COSTS
AND SCHEDULES
., "..-,......,.... "' "''* WL =~--==--=-~"""""''=-=-.,..~-~-~~------~--·~--.b~=~~~--,--
8.0
8.1
>-•
-
'-·'
CONSTRUCTION COSTS AND SCHEDULES
Estirnates of Cost
Estirnates of construction costs have been prepared for
the following alternatives for project developrnent:
Alternative A -400 MW McArthur tunnel developrnent
Alternative B -330 MW McArthur tunnel developrnent
Alternative C & D -300 MW Chakachatna tunnel
developrnent
The estirnates are based on schedules of quantities of
rnaterials and equiprnent needed for the major features of
each alternative to the extent perrnitted by the drawings
for Section 3.0 of this report. In sorne cases,
quantities were proportioned from the construction
records of other projects bearing significant sirnilarity
of structures and conditions expected to be encountered
during construction of the Chakacharnna Hydroelectric
Project. Unit priees developed for this and ether
projects involving sirnilar types of construction and from
analyses of bids received for the construction of sirnilar
types of projects in Alaska, adjusted as necessary to
reflect January 1982 priee levels, were then applied to
the schedules of quan-tities to arrive at the estirnated
costs set forth in the estirnate surnrnaries at the end of
this section of the report. The surnmaries show the
following estirnated project costs excluding owner's costs
and escalation:
8-1
Alternative A $1.5 billion
Alternative B $1.45 billion
Alternative C $1.6 billion
Alternative D $1.65 billion
The above costs include a 20% contingency added to the
specifie construction cost plus engineering and
construction management, and interest during
construction. The costs for Alternatives B and D
additionally include a provisional allowance of $50
million for fish passage facilities at the lake outlet.
For all of the alternatives, the principal structures
consist of the following:
o Intake structure at Chakachamna Lake with underwater
lake tapping, and control gate shaft.
o Concrete lined power tunnel with construction access
adits.
o Surge chamber and emergency closure gates at the down-
stream end of the power tunnel.
o Underground concrete lined pressure penstock shaft and
manifold.
o Concrete and steel lined penstock branches leading to
a valve chamber and the turbines.
o Four unit underground powerhouse with exploratory adit
(to become the ventilation tunnel) and main access
tunnel.
8-2
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-
8.1.1
"-
o Underground transformer vaults and high voltage cable
gallery.
o Tailrace tunnel and surge chamber.
o Tailrace outlet channel and river protection works.
o High voltage cable terminals and switchyard.
o Transmission lines to northerly shore of Knik Arm.
o High Voltage submarine cable crossing of Knik Arm.
Power Tunnel
The cast of constructing the power tunnel is the dominant
feature, representing more than half the estimated cost
of constructing each alternative. Detailed evaluations
were made of all operations and the direct costs
considered necessary to construct the 25-foot diameter
concrete lined power tunnel for Alternatives A, C and D,
using bath rubber tired and rail haulage equipment. The
difference in cast between the two was found to be
small. Thus, the choice of haulage equipment will
probably be determined by other considerations such as
for example, whether excavation and concrete placement
would be scheduled by a Contractor to take place
concurrently in a given tunnel heading. This can be
accomplished if necessary in a 25-foot diameter tunnel
with either rail haulage or rubber tired equipment.
The estimated cast of constructing the 23-foot diameter
tunnel required for Alternative B is proportioned from
the estimated unit cast per lineal foot for constructing
the 25-foot diameter tunnel for Alternatives A, C, and D.
8-3
The estimated tunnel construction costs are based on the
following items:
o Excavation would be by conventional drilling and
blasting generally with full face excavation, drilling
12-foot depth rounds. Allowance is included for a
nominal length of tunnel where the depth of rounds
might have to be reduced, or where top heading and
bench techniques might have to be used temporarily, if
less favorable ground conditions are encountered.
o The assumptions are made that 25% of the tunnel length
would require steel rib support, 25% would be suppor-
ted by patterned rock bolts and 50% would be
unsupported.
o Chain link mesh for the protection of workmen from
rock falls is provided above the spring line over the
full tunnel length.
o Estimated excavation costs include provision for hand-
ling and removing 2000 gallons per minute of ground
water inflow in each tunnel heading.
o Excavation and concrete lining would proceed on a
3-shift basis, 6-days per week.
o Construction access adits would be located near the
upstream and downstream ends of each tunnel alter-
native. In addition two intermediate adits would be
provided for Alternatives C and D.
8-4
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-
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-
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,_
,_,
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------------------~ .. ~~~~-----------
8.1.2 Underground Powerhouse and Associated Structures
For purposes of the current estimates, the powerhouse has
been taken as an underground installation for each alter-
native, with a high pressure penstock shaft and low
pressure tailrace tunnel. The estimates of cost are
based on the following conditions:
o All excavation and concrete work would proceed on a
3-shift, 6-days per week basis.
o The powerhouse cavern, valve chamber and tailrace
tunnel would be excavated by top heading and bench.
o The penstock and surge shafts would be excavated first
by pilot raise, then by downward slashing to full
diameter.
o Excavation for the horizontal penstock and manifold,
access tunnel, cable gallery and draft tubes would be
full face.
o Chain link mesh is provided for protection of workmen
over the upper perimeter of all excavations exceeding
12-feet in height.
o All permanent excavations would be supported as deter-
mined necessary by patterned rock bolts.
o Allowance is included for lining the upper perimeters
of all caverns, chambers and galleries required for
permanent access and those housing vulnerable genera-
ting or accessory equipment with wire mesh reinforced
shotcrete (this may only be needed locally according
to rock conditions exposed during construction) •
8-5
8.1.3
o Excavation of an exploratory adit, and a program of
core drilling and rock testing will precede and con-
firm the suitability of the site for the underground
powerhouse complex during the design phase and the
costs thereof are included in the estimates.
o The costs included for the major items of mechanical
and electrical equipment are based on current data
with added allowance for delivery and transportation
to the powerhouse site. Installation costs are also
included.
o Costs of mechanical and electrical auxiliary equipment
and systems, control and protective equipment are
included.
Tailrace Channel
The estimates include a monetary allowance for the con-
struction of an outlet channel and river training works
to protect it from damage during floods in the river.
Details of such requirements are not well defined at the
present stage but it is contemplated that extensive use
would be made of rock spoil from excavation of the power-
house complex for these purposes.
-
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-
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River gravels excavated from the tailrace channel would -
be processed and used to the maximum extent possible for
concrete aggregate. ......
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....
8-6 .....,
-------~--~--------~~---~-·-·-····----
8.1.4
,_,
,_
8 .1. 5
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'-'
8.1.6
'"""'
'-
--
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Switchyard
In each alternative, due to space limitations, the
switchyard would be located outside the mouth of the can-
yon on gently sloping land and an appropriate allowance
is included in the estimates for their cast.
Transmission Line and Cable Crossing
Field data acquisition is not scheduled until the 1982
exploratory program and information regarding construc-
tion conditions is limited to aerial observation of the
proposed transmission line alignment and cable crossing.
The cast allowed in the estimate for the transmission
line is based on experience and includes the estimated
cast of the submarine cable crossing to a dead end
structure on the Anchorage Shore of Knik Arro.
Site Access and Development
The estimates include costs of constructing access and
support facilities needed for construction of the perma-
nent works. These would consist basically of the
following installations:
o Unloading facility on tidewater at Trading Bay, com-
plete with receiving and warehousing provisions, bulk
cement and petroleum fuels storage plus a small camp
for operating staff.
8-7
o Gravel surfaced all-weather access roads to construc-
tion sites. It has been assumed that where existing ~
roads are suitably located, permission to use them
could be negotiated with their owners in exchange for
improvements that would include widening them to full
two-way traffic roads. Bridges and culverts would be
provided at all streams and water courses and where
needed for drainage. Year-round maintenance costs are
included throughout the construction period.
o An aircraft landing facility with a runway of suffi-
cient length to handle aircraft up to DC-9 and 737
types, and ground support facilities.
o For Alternatives A and B major construction camps
would be located outside but close to the mouth of the
McArthur Canyon to accommodate workers employed on the
downstream heading of the power tunnel, the powerhouse
and associated structures. A second camp for workmen
employed on the upstream heading of the power tunnel
and intake works would be provided just east of the
Barrier Glacier on the northerly side of the river.·
o For Alternatives C and D the main construction camp
would be located outside the mouth of the Chakachatna
Canyon for workers employed on the downstream heading
of the power tunnel, the powerhouse and associated
structures and also for the second intermediate access
w
....,J
adit tb the power tunnel. A second camp for workers ~
employed on the upstream heading of the power tunnel,
intake works and headings driven from the first inter-
mediate access adit to the power tunnel would be
located east of the Barrier Glacier.
8-8
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-
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-
-
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......
0 The construction camps would be self-contained with
all needed support facilities which would include
water supply, sewage treatment, solid waste disposa!,
catering and medical services.
o Electrical power during construction is provided for
on the assomption that diesel driven equipment would
be used.
o Major cornpressed air facilities would be required for
the excavation work and their cost is provided for in
the estimates.
0 Camps needed to accommodate transmission line workers
would be light weight "fly camps". Much of the line
work would be undertaken in winter and would be
avoided during waterfowl nesting periods.
As construction work approaches cornpletion, all temporary
facilities will be dismantled and removed from the site,
which will be restored insofar as is possible to its ori-
ginal condition, and the cost of such demobilization and
site restoration is included in the estimates.
Exclusions from Estimates
The estimates of construction costs do not include provi-
sion for the costs of the following items:
o Owner's administrative costs.
o Financing charges.
o Escalation
8-9
8.3
o Land and Land Rights.
o Water Rights
o Permits, licenses and fees.
o Switchyard at the Anchorage transmission line terminal.
Construction Schedules
Typical construction schedules are shown on Figure 8-2
for Alternatives A and B and on Figure 8-3 for Alterna-
tives C and D. These schedules have as their beginnings
the existing schedule for completion of the project feas-
ibility study and preparation of the application to the
Federal Energy Regulatory Commission (FERC) for a license
to construct the project.
The assumption has been made that the license application
would be submitted to FERC March 1, 1983. Assuming also
that the FERC licensing process continues in much the
same manner as it does at the present time, an early step
will be the preparation of an environmental assessment of
the project by FERC staff. This generally takes about 12
months following which is a 60-day period for review and
comment by interested agencies. Thus, by the end of
April, 1984, it should have become clear whether there
are any outstanding unresolved issues. If there are not,
then it would be possible to forecast with reasonable
certainty that the FERC license would be issued in early
1985, in which event there would not appear to be any
reason why the construction of access facilities and camp
installations could not commence by June 1, 1984. In
order to provide adequate lead time to commence design
8-10
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-
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.. _
1-,
"'-
-
"-'
and prepare plans and specifications for the construction
of access facilities, design engineering of the project
would need to commence at the beginning of 1984.
Noting that there is a possibilit.y that FERC might also
require completion of an exploratory adit and rock
testing program at the powerhouse site before issuing the
project license, June 1, 1984 would appear to be a logi-
cal time to commence that program. Making an early start
in the manner described above would permit the plant to
commence commercial operation a year earlier than if the
design of the project and construction of infrastructure
did not commence until after the FERC license bad been
issued.
Construction of the power tunnel lies on the critical
path for completion of development via the McArthur River
in Alternatives A and B. The schedule is based on the
tunnel excavation advancing at an average rate of approx-
imately 26 feet per day in each heading. At that rate,
excavation would be completed in 3-1/2 years. Placement
of the concrete lining would proceed concurrently with
the excavation in both headings. Total construction time
for the tunnel is thus 50 months and the first unit in
the powerhouse could be started up by August 1, 1990. As
discussed in section 10.2.4 of this report, a significant
saving in time might be effected if the rock is suitable
for tunnel excavation to be performed by means of a
boring machine and also if any lengths of the tunnel can
be left unlined.
8-11
For development via the Chakachatna River in Alternatives
c and D, the ability to provide two intermediate con-
struction access adits enables the tunnel construction to
be completed within 32 months, or 18 months less than for
the McArthur tunnel. Timely delivery of the turbines and
generators, and construction of the powerhouse complex
becomes more critical. Asssuming an early start on site
access and development as described above for Alterna-
tives A and B, the first unit in Alternatives C and D
could be started up by February 1, 1989, or 18 months
earlier than would be the case with Alternatives A and B.
The implications of this are discussed in Section 7.3.5
of this report.
8-12
--
-
-
-
CIO
1
l-' w
f r r r r r
CHAKACHAMNA HYDROELECTRIC PROJECT
CONCEPTUAL ESTIMA TE SUMMARIES-SHEET 1 OF 2
ESTIMATED COSTS IN THOUSANDS OF DOLLARS
ALTERNATIVES
A B c
LAND AND LAND RIGHTS 0 0 0
POWER PLANT STRUCTURE AND IMPROVEMENTS
Valve Chamber 5,600 5,500 5,600
Underground Power House 26,200 25,200 26,200
Bus Galleries 200 200 200
Transformer Gallery 4,600 4,300 4,300
Valve Chamber and Transformer 400 400 400
Gallery -Access Tunnel
P. H. Access Tunnel 13,500 13,500 13,500
Cable Way 800 800 800
51,300 49,900 51,000
RESERVOIR, DAM AND WATERWAYS
Reservoir 100 100 100
lntake Structure 10,400 9,300 10,400
1 ntake Gate Shaft 13,200 12,400 13,200
Access Tunnel
-At lntake 21,600 19,100 21,600
~ At Surge Chamber, No, 3 6,600 5,900 8,900
-At Mile 3, 5, No. 1 0 0 2û,8ûû
-At Mile 7, 5, No. 2 0 0 14,500
Power Tunnel 626,800 580,400 712,500
Surge Chamber -Upper 12,900 11,000 12,900
Penstock-lnclined Section 18,000 16,500 15,400
-Horizontal Section and Elbow 6,700 6,000 6,700
-Wye Branches to Valve Chamber 13,200 11,900 12,100
-Between Valve Chamber & Power House 800 600 800
Draft Tube Tunnels 1,900 1,700 1,900
Surge Chamber -Tailrace 2,400 2,400 2,400
Tailrace Tunnel and Structure 10,300 9,600 10,300
Tailrace Channel 900 700 900
River Training Works 500 500 500
Miscellaneous Mechanical and Electrical 7,100 6,100 5,700
753,400 694,200 871,600
---------- ---------1-------------
D
0
5,600
26,200
200
4,300
400
13,500
800
51,000
100
10,400
13,200
21,600
8,900
'ln ann ~u,u--
14,500
712,500
12,900
1 15,400
6,700
12,100
800
1,900
2,400
10,300
900
500
5,700
871,600
00
1 ......
ol::>o
l,
CHAKACHAMNA HYDROELECTRIC PROJECT
CONCEPTUAL ESTIMA TE SUMMARIES-SHEET 2 OF 2
ESTIMATED COSTS IN THOUSANOS OF DOLLARS
ALTERNATIVES
A B c
TURBINES AND GENERA TORS 67,900 57,900 54,500
ACCESSORY ELECTRICAL EOUIPMENT 11,200 9,500 9,000
MISCELLANEOUS POWER PLANT EOUIPMENT 8,600 7,300 6,900
SWITCHYARD STRUCTURES 3,600 3,600 3,600
SWITCHYARD EOUIPMENT 13,800 12,500 12,100
COMM. SUPV. CONTROL EOUIPMENT 1,600 1,600 1,600
TRANSPORTATION FACIUTIES
Port 4,600 4,600 4,600
Airport 2,000 2,000 2,000
Access and Construction Roads 59,600 59,600 44,100 --66,200 66,200 50,700
TRANSMISSION UNE & CABLE CROSSING 63,200 63,200 56,500
TOTAL SPECIFIC CONSTRUCTION COST AT 1,040,800 965,900 1,117,500
JANUARY 1982 PRICE LEVELS
ENGINEERING & CONSTRUCTION MANAGEMENT 124,900 115,900 134,100
SUBTOTAL 1,165,700 1,081,800 1,251,600
CONTINGENCY @20% 233,100 216,400 250,300
ESCALATION Not Incl. Not Incl. Not Incl.
INTEREST DURING CONST. @3% PER ANNUM 111,900 104,100 101,400
OWNER'S COSTS Not Incl. Not Incl. Not Incl.
ALLOWANCE FOR FISH PASSAGE FACILITIES -50,000 -
TOT AL PROJECT COST AT 1,510,700 1,452,300 1,603,300
JANUARY, 1982 PRICE LEVELS
USE 1,500,000 1,450,000 1,600,000
----~~
1 t " 1 l,
l
0
54,500
9,000
6,900
3,600
12,100
1,600
4,600
2,000
44,100
50,700
56,500
1,117,500
134,100
1,251,600
250,300
Not Incl.
101,400
Not Incl.
50,000
1,653,300
1,650,000
ECONOMIC EVALUATION
·-
~'~ 9.0
9.1 -
'-'
.....
._.
9.2
-
._
-
ECONOMIC EVALUATION
General
An evaluation has been made of the economie tunnel
diarneter as well as the economie tunnel length for the
four basic alternatives presented in this report.
Determination of the economie tunnel diameter involves
comparing the construction costs of tunnels of varying
diameters, with the present worth of the difference in
power produced over the life of the project as a result
of the changes in hydraulic loss in the tunnel as the
diameter is varied. The economie tunnel length is
determined from an economie balance between the cost of
increasing the tunnel length to develop additional head
on the powerhouse, and the present worth of the additional
power produced by the higher head over the life of the
project •
Parameters for Economie Evaluation
Alaska Power Authority has developed the following
parameters for economie analyses of hydroelectric
projects.
Inflation Rate
Real Discount Rate
Economie Life of Hydroelectric Projects
Economie life of thermal plants
(conventional coal fired or
combined cycle)
9-1
0%
3%
50 years
30 years
9.3
9.3.1
In sizing the various project elements, i.e., tunnel
diameter and length, the value of power generated by the
hydroelectric project has been considered equal to the
cost of the equivalent power generated thermally by coal
fired plant or by natural gas fired combined cycle plant.
As agreed with APA, in order to arrive at a project cost
-
-
which can be readily compared with that for the Susitna •
Project a 50% plant factor has been used for determining
the installed capacity of the power plants discussed in
this report. Future studies will concentrate on refining
the preferred plant factor for the project.
Cost of Power from Alternative Sources
General
To ensure uniformity of data between the various
feasibility studies of hydroelectric projects which are
currently in progress, including the Susitna
Hydroelectric Project, APA requested that the following
sources be used for the development of cost of power from -
alternative thermal generation:
(1) Acres American Incorporated report "Susitna
Hydroelectric Project" Task 6 Development Selection
Report, Appendices A through I, July 1981 for
construction cost of coal fired and combined cycle
thermal plants.
(2) Battelle Pacifie Northwest Laboratories, for the
cost of operation and maintenance and fuel for coal
fired and combined cycle thermal plants. Data on
these items were obtained during a visit to
Battelle's office on September 1, 1981.
9-2
~
-i
~
-
'-
-
.....
-
"-
-
-
""""
-
·-
.. --------------------------------------------------------~~~--~---------=~~~ & , ·---------.
9.3.2 Construction Cost
(a)
(b)
Coal fired thermal plant:
The Acres Arnerican report referred to above develops
the construction cast of a 250-MW coal fired thermal
plant at Beluga in 1980 dollars ta be $439,200,000
direct construction cast and $627,650,000 total cast
including 16% contingency, 10% for construction
facilities and utilities and 12% for Engineering and
Administration, but not including interest during
construction. This total cast corresponds ta
$2510/kW. Including interest during construction at
3 percent per year for a 6 year construction period,
the total cast amounts ta $2706/kW. (This differs
but little from the $2744/kW value given in Table
B.l3 of the Acres Report apparently because of sorne
rounding of nurnbers in the! Acres calculation and
apparently slight difference in cash flow during the
construction period.)
Combined Cycle Plant
The Acres American report also develops the
construction cost of a 250-MW combined cycle plant
in 1980 dollars to be $121,830,000 direct
construction cast and $174,130,000 total cost
including 16% contingency 10% for construction
facilities and utilities and 12% for Engineering and
Administration, but not including interest during
construction. This corresponds ta $697/kW. When
interest during construction is added at 3 percent
per year, the total cost is $707.5/kW.
9-3
9.3.3
9.3.4
Operation & Maintenance Cost
Data obtained from Battelle is summarized below for 1980
priee levels.
(a) Coal-fired Thermal Plant
Fixed Operation and Maintenance $16.71/kW/year
variable Operation and Maintenance 0.6 mills/kWh.
Escalation above general inflation rate 1.9% until
year 2012 with no escalation after 2012.
(b) Combined Cycle Plant
Fixed Operation and Maintenance $35.00/kW/year
variable Operation and Maintenance 0 mills/kWh.
Escalation above general inflation rate 1.9% until
year 2012 with no escalation after 2012.
Fuel Cost
Data obtained from Battelle is summarized below for 1980
priee levels
(a) Coal from Beluga
Fuel cost $1.09/mill. BTU
Escalation above general inflation rate 1.5% until
year 2012 with no escalation after 2012.
Heat Rate 10,000 BTU/kWh.
9-4
-
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-
-
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-
-
-
iv
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-
-..
-
-
,,_
(b) Natural Gas -Combined Cycle Plant
The natural gas priees as estimated by Battelle for
the future years are given in Table 9-1.
rleat rate 7500 BTU/kWh.
TABLE 9-1
NEW CONTRACT GAS PRICE (AML&P) -ANCHORAGE
Year Gas Priee
$/Mill BTU
1980 1.08
1981 1.08
1982 1.09
1983 1.09
1984 1.09
1985 1.09
1986 1.35
1987 1.56
1988 l 1.65
1989 1.89
1990 2.11
1991 3.62
1992 3.74
1993 3.86
1994 3.98
1995 4.11
Foreeast esealation after 1995 = 3% per year unti1 the
year 2012, and no esealation thereafter.
9-5
9.4 Value of Hydra Generation
The value of the hydra generation is established by
determining the cast of generating power from alternative
sources. For the purpose of this study an analysis has
been made of the cast of alternative coal-fired and
combined cycle generation, using the basic cast data
presented previously in Section 9.3.
The annual cost of interest, depreciation and insurance
for the alternative thermal plants were calculated on the
following basis:
Interest
Depreciation (30 year life)
In surance
Annual Charge on
Capital Cast
3.0%
2.1%
0.25%
5.35%
Based on an arbitrary selection of 1990 as the in-service
date for the Chakachamna Project and examining a fifty
year period, equal to the economie life of the hydra
plant, and using the unit costs for thermal generation
discussed above, comparative costs were prepared for each
year of the 50 year period of the cost of generating
power at 50% load factor by each of the two alternatives,
conventional thermal using Beluga coal and combined cycle
using gas. These annual costs over the 50 year period
were then used to determine their present worths at the
first year of generation taken as 1990. The calculations
were performed on a cost per kWh basis and are presented
in Tables 9-2 & 9-3 for the conventional coal fired and
combined cycle cases respectively.
9-6 -
'--
~
-
,_
-
~~
--
-
-
-
-
-
'-'-"
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TABLE 9-2 (Sheet 1 of 2)
COAL FIRED PLANT
Year
Amortization
& Insurance O&M Fuel Total
Present
Worth
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
33.02
5.32
5.42
5.52
5.63
5.74
5.84
5.96
6.07
6.18
6.30
6.42
6.54
6.67
6.79
6.92
7.06
7.19
7.33
7.47
7.61
7.75
7.90
7.90
7.90
7.90
12.65
12.84
13.03
13.23
13.43
13.63
13.83
14.04
14.25
14.46
14.68
14.90
15.12
15.35
15.58
15.82
16.05
16.29
16.54
16.79
17.04
17.29
17.29
17.29
17.29
50.99
51.28
51.57
51.88
52.19
52.49
52.81
53.13
53.45
53.78
54.12
54.46
54.81
55.16
55.52
55.90
56.26
56.64
57.03
57.42
57.81
58.21
58.21
58.21
58.21
-------
49.50
48.34
47.19
46.09
45.02
43.96
~2.94
41.94
40.96
40.02
39.10
38.20
37.32
36.47
35.64
34.84
34.04
33.27
32.52
31.79
31.08
30.38
29.49
28.64
27.80
946.54
NOTE: Escalation rates above the general escalation rate are as
follows.
Amortization & Insurance -Nil.
Qperation & maintenance -1.9% for first 22 years only
Fuel -1.5% for first 22 years only.
9-7
Year
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
TABLE 9-2 (Sheet 2 of 2)
COAL FIRED PLANT
Amortization
& Insurance O&M
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
33.02 7.90
Fuel
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
17.29
Equivalent Levelized Annual Cost = 55.60 mills/kWh.
9-8
~
Present
Total Worth
Fwd. 946.54
58.21 26.99
58.21 26.21
58.21 25.44
58.21 24.70
58.21 23.98
58.21 23.28
58.21 22.61
58.21 21.95
58.21 21.31
58.21 20.69
58.21 20.08
58.21 19.50
58.21 18.93
58.21 18.38
58.21 17.84
58.21 17.32
58.21 16.82
58.21 16.33
58.21 15.85
58.21 15.39
58.21 14.94
58.21 14.51
58.21 14.09
58.21 13.68
sa. 21 13.28
1430.64
--
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TABLE 9-3 (Sheet 1 of 2)
COMBINED CYCLE PLANT
Amortization Present
Year & Insu rance O&M Fuel Total Worth
1 8.64 9.64 21.1 39.38 38.23
2 8.64 9.82 36.2 54.66 51.52
3 8.64 10.01 37.4 56.05 51.29
4 8.64 10.20 38.6 57.44 51.03
5 a. 64 10.39 39.8 58.83 50.75
6 8.64 10.59 41.1 60.33 50.53
7 8.64 10.79 42.33 61.76 50.22
8 8.64 11.00 ~13. 60 63.24 49.92
9 8.64 11.21 44.91 64.76 49.63
10 8.64 11.42 416.26 66.32 49.35
11 8.64 11.64 47.65 67.93 49.07
12 8.64 11.86 419.08 69.58 48.80
13 8.64 12.08 S0.55 71.27 48.53
14 8.64 12.31 S2.06 73.01 48.27
15 8.64 12.55 S3.63 74.82 48.02
16 8.64 12.78 S5.23 76.65 47.77
17 8.64 13.03 S6.89 78.56 47.53
18 8.64 13.28 S8.60 80.52 47.30
19 8.64 13.53 60.36 82.53 47.07
20 8.64 13.78 62.17 84.59 46.84
21 8.64 14.05 64.03 86.72 46.62
22 8.64 14.31 65.95 88.90 46.40
23 8.64 14.31 65.95 88.90 45.04
24 8.64 14.31 65.95 88.90 43.73
25 8.64 14.31 65.95 88.90 42.46
1195.92
NOTE: Escalation rates above the general escalation rate are as
follows.
Amortization & Insurance -Nil.
Operation & maintenance -1.9% for first 22 years only
Fuel -1.5% for first 22 years only.
9-9
"---------------------------------------------'"'
Year
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
TABLE 9-3 (Sheet 2 of 2)
COMBINED CYCLE PLANT
Amortization
& Insurance O&M Fuel
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8. 64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
8.64 14.31 65.95
Equivalent Levelized Annual Cost = 75.2lmills/kWh.
9-10
f t:
..i
Present
Total Worth
Fwd. 1195.92
88.90 41.22
88.90 40.02
88.90 38.86
88.90 37.72
88.90 36.63
88.90 35.56
88.90 34.52
88.90 33.52
88.90 32.54
88.90 31. 59·
88.90 30.67
88.90 29.78
88.90 28.91
88.90 28.07
88.90 27.25
88.90 26.46
88.90 25.69
88.90 24.94
88.90 24.21
88.90 23.51
88.90 22.82
88.90 22.16
88.90 21.51
88.90 20.89
88.90 20.28
1935.25
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9.5
~~~~""'" ~---·---------
The levelized annual cost of generation by a coal fired
plant using Beluga coal is calculated to be 55.60 mills
per kWh compared with 75.21 mills per kWh for the
combined cycle plant, based on 50% load factor
generation. The higher cost for the combined cycle plant
is due primarily to a higher initial fuel cost, a much
higher escalation on the cost of fuel, and somewhat
higher operation and maintenance cast. Taken
collectively these more than offset the much lower annual
charge on the capital cost of constructing the combined
cycle plant. The cast of power produced by the coal
fired plant was therefore adopted as the alternative for
establishing the value of hydro generation.
The capital cast of a hydro plant which gives a levelized
annual cast over the 50 year life equal ta the levelized
annual cast of the coal fired thermal plant of 55.60
mills per kWh, based on 50% plant factor, and including a
credit of 5% less installed capacity required in a hydro
plant because of the reduced system reserve requirements
with hydra generation, is calculated ta be $6,117 per
kW. This total cost includes contingency, construction
camp facilities, engin€\ering, and construction management
and interest during construction.
Economie Tunnel Sizing
The economie diameter of the main power tunnel has been
investigated by comparing the incremental cast of varying
the tunnel diameter with the incrementai value of the
difference in power produced as a result of such
variation in tunnel diameter. :~or the same powerhouse
flow, increasing the tunnel diameter reduces the head
lasses in the tunnel thereby increasing the total head on
the powerhouse with a consequent increase in power
production.
9-11
/,
In establishing the variation in estimated tunnel
construction cost it bas been assumed that the tunnel
will be fully concrete lined with the typical horseshoe
section shawn in Figure 3-2. Future studies are planned
to evaluate the merits of a nominally unlined tunnel.
For the case of Alternatives A & C with no water release
to meet instream flow requirements in the Chakachatna
River (i.e., all controlled water being diverted for
power production purposes) , Figure 9-1 shows the plot of
estimated tunnel construction cost and value of power
production with variation in tunnel diameter. This curve
_,
--
11!'!11
"'-
shows that the economie diameter of a concrete lined ~
tunnel is 25 feet. In Alternative B, with the flow
diverted to a powerhouse sited on the McArthur River, but ~
with water reserved for instream flow requirements in the
Chakachatna River as discussed in Section 7.3.3, a
separate study to establish the economie diameter was not
made. Instead, as an approximation, the tunnel diameter
was selected such that the velocity of flow through the
tunnel with the generating units operating at full output
and at full level at Lake Chakachamna would be the same
as that obtained under these same operating conditions in
Alternative A for which the economie diameter had been
calculated. This approximation gives a 23-foot tunnel
diameter which is believed reasonable at this stage, but
future studies will review its acceptability.
In the case of Alternative D where only an average
release of 30 cfs flow is maintained below Chakachamna,
~
Lake, the 25 foot diameter tunnel was retained, since the •
powerhouse flow differs by less than 1%.
w
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9-12
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9.6 Economie Tunnel Length
For both basic alternative developments by diversion to
the McArthur River or downstream along the Chakachatna
River, an examination has been made of the economie
tunnel length. As the powerhouse is moved downstream to
develop additional head, the power tunnel becomes longer
and hence more costly. The economie tunnel length is
therefore determined from an economie balance of
estimated tunnel construction ciost and value of power
produced. Based on the value of the hydre generation as
discussed in Section 9.4, the present worth of the power
produced by 1 foot of head when all controlled water is
used for power generation is equal to approximately
$3,500,000 which corresponds to $139,000 annually over
the 50 year life of the plant at 3% rate of interest.
The economie balance includes consideration of the
additional estimated tunnel construction cast by
increasing the tunnel length, additional powerhouse cost
to develop the power produced from the additional head
and the value of the additional power generated by the
additional head developed. The additional head is based
on the increased gross head due to the lower tailwater
obtained by extending the tunnel less the increased
friction head loss in the longer tunnel.
Figure 9-2 and 9-3 show respectively the plots of the
economie tunnel length for the development via the
McArthur River and down the Chakachatna River. The final
selected tunnel lengths and corresponding powerhouse
locations are shown in Figures 3-2 and 3-3 •
9-13
1982 STUDY PROGRAM
------------------------·~ ::m:, t""-=---~-J·:•"'"'"_,.,..--_,.,,.,,,,,.,?••~., .. -,~~··••••··~~~~---m-.._,.._,
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10.0
10.1
10 .1.1
10.1.2
1982 STUDY PROGRAM
Engineering Studies
Since development of the project by means of a tunnel to
a powerhouse located in the McArthur Valley will yield
the maximum electrical power benefits at lowest unit
cost, the 1982 engineering studies are planned to
concentrate on optimizing the structures and layout for
that form of development. Due to the limitation on
availability of funds until after June 30, 1982, the main
thrust will be delayed until such time as the allocation
of funds will permit.
Hydrological Studies
Extension of the Chakachamna Lake outflow records by
correlations with other stations will be completed and
power studies will be made using lake inflows derived
from the extended outflows. It appears that satisfactory
correlations can be established to derive discharge
records that will extend the date base from 12 years to
31 years. Studies will also be made to examine the
effects bn power generation of limiting the allowable
range of lake water surface elevation •
It is planned to purchase meteorological instruments
necessary to record field date needed for studies that
will evaluate the effects of operation of the project on
the water temperature structure of Chakachamna Lake.
Chakachatna Dam
As was discussed earlier in Section 3.2 of this report
consideration of dam sites on the Chakachatna River was
placed in obeyance in the initial studies because of
problems that were immediately evident. These ,comprised
10-1
10 .1. 3
10 .1. 4
foundation problems in the left abutment and in the river
channel, siting difficulties for a spillway capable of
handling flood flows in the order of half a million cubic
feet per second, hazards posed by future eruptions of
Mount Spurr, and possibility of problems that may develop
at the lake outlet. It is planned to re-examine the
situation to verify that nothing has been overlooked
-
before completely dismissing the possibility of a dam as ~
a viable alternative.
Reservoir and Fish Passage Facilities
Studies will be conducted to examine how an outlet could
be provided that would permit fish passage into and out
of the reservoir.
Power Intake and Tunnel
Mr. Christian Groner, a consulting engineer of
international repute with extensive experience in lake
tapping projects has been contacted and indicated his
willingness to make his expertise available in developing
plans for the tapping of Chakachamna Lake.
The optimum tunnel length and diameter will be reviewed
and recalculated, if necessary, according to revisions in
the data base. When data become available from the
tunnel line geological exploration, as assessment will be
made of the feasibility and savings in cost and schedule
that may be attainable if a nominally unlined tunnel
instead of a concrete lined one were to be constructed in
those locations where rock quality would permit.
10-2
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10 .1. 5
10 .1. 6
After sorne indication has been obtained regarding the
physical properties and composition of the rock, it is
also planned to evaluate the feasibility of excavating
the power tunnel by tunnel boring machine. A tunnel of
comparable size was recently bored on the Kerckhoff II
project in California Sierra granite. A bored tunnel
would have a potential for significant savings in cast by
virtue of possible reductions in time and labor needed
for excavation, rock support and in volume of concrete
needed for lining the tunnel.
Underground Powerhouse Complex
Studies are planned to optimize the penstock
configuration and layouts for the manifold, value
chamber, powerhouse cavern, draft tubes, access and
tailrace tunnels, and the transformer and high voltage
cable galleries. General arrangements and equipment
layouts will be prepared for the major components.
Performance data for the major mechanical and electrical
equipment will be defined.
Transmission Line and Submarine Cable Crossing
The planned alignments for the transmission line and
cable crossing will be determined. Requirements for
tower foundations, tower types and conductors will be
evaluated and identified. It is planned to engage the
services of Mr. H.B. White, a transmission line
consultant of international repute to advise in all
aspects of the transmission line route location and
design.
10-3
10 .1. 7
10 .1. 8
10 .1. 9
Access Roads and Construction Facilities
Alignments for the access road system required for the
project construction and operation will be selected.
These will include access to the permanent facilities in
both the Chakachatna and McArthur valleys. The location
and size of construction camps, airstrip and unloading
facilities at Trading Bay and other temporary
construction facilities will also be defined.
Cost Estimate and Construction Schedule
Based on the layouts developed for the various project
structures, quantities will be prepared. From these, the
project cost estimate and construction schedule will be
developed.
Feasibility Report and FERC License Application
The proposed 1982 studies are planned to culminate in the
preparation of a formal project feasibility report that
will identify the recommended form of development with
firm estimates of the power benefits and updated
estimates of the cost of construction comparison with
other power sources will also be made. The preparation
of the exhibits for tbe FERC license application will be
based on the form of development identified in the
feasibility report.
10-4
'*""'
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10.2
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Geologie Studies
Elements planned for inclusion in the 1982 program of
geologie studies include:
(1) A two week program of detailed field investi-
gations of faults and lineaments that may be faults,
which have been identified in the project area on
the basis of the literature review, air photo
analysis, field reconnais-sance, and analysis of
low-sun-angle aerial,photography.
(2) A field investigation of the geology along the
proposed tunnel alignment and at the proposed
powerhouse site. The investigation will include
mapping of pertinent geologie features, a limited
geophysical investigation of sub-surface conditions
at the proposed powerhouse site and of lake bottom
characteristics at the proposed lake tap site, and a
drilling program at the proposed powerhouse site.
(3) A brief geologie and geophysical study of aggregate
sources in and around the site proposed for project
facilities.
( 4) A reconnaissance of the geologie conditions along
the proposed road and transmission line alignment.
(5) Preparation of those components of the feasi-bility
study report that address geologie factors.
10-5
10.3 Environmental Studies
During the two reconnaissance level efforts conducted in
1981, areas and species that may be impacted by the
proposed alternatives were identified. While hydrologie
efforts were concentrated on assessing the effects of the
alternatives on the characteristics of the major rivers,
fisheries investigations were conducted to evaluate the
species and age class distributions. Together, these
disciplines derived a preliminary assessment of the
minimum amount of water that would need to be released
from the lake into the Chakachatna River so that fish
migrations would not be obstructed. Terrestrial
investigations concentrated on the species distribution
and relative abundance of both vegetation and wildlife.
The socioeconomic investigations centered on identifying
the major concerns of the government agencies and the
general public.
Although significant data were collected in all
disciplines, more information will need to be gathered
during 1982 so that site specifie impacts can be
identified. The 1982 environmental studies are designed
to provide data sufficient to prepare:
o a final Chakachamna Hydroelectric Project feasibility
report~ and
o environmental exhibits to accompany the Alaska Power
Authority's License Application to the Federal Energy
Regulatory Commission.
10-6
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10.3.1
A preliminary design of the 1982 study program is
presented below for the disciplines of environmental
hydrology, aquatic biology, wildlife biology, and human
resources. A more detailed work program is being
prepared for presentation at program scoping meetings
with State and Federal Agencies in December 1981.
Environmental Hydrology
The objectives of the 1982 environmental hydrology study
prog~am are to collect data and conduct analyses
sufficient to:
o assess the impacts of project flow regulation of the
physical process of the Chakachatna and McArthur River
systems; and
o allow the aquatic bilogy, wildlife biology, and human
resources disciplines to meet their study objectives.
The studies are designed to provide more detailed
information of the type presented in Sections 6 and 7 so
that a more detailed impact assessment can be conducted.
Hydrologie data collection will include a network of
stream gages to establish the seasonal and areal
distribution of flow in the Chakachatna and McArthur
River systems. Discharge measurements will be taken
periodically to establish rating curves. Water quality
data will be collected as necessary for the FERC license
application and to support the aquatic biology studies.
Selected wetlands will be investigated to identify their
water sources and the potential impacts of regulating
flow.
10-7
Hydraulic studies will include the evaluation of a number
of stream and floodplain transects encompassing sites
with gages as well as other areas selected from fishery
habitat information. More specifie information on the
number and locations of transects will be included in the
detailed study plan. Hydraulic parameters will be
collected where discharge measurements are taken and also
in other site specifie locations as needed to support the
fisheries investigations. Water surface profiles will
also be surveyed.
Channel configuration and other regime characteristics
will be investigated. Channel configuration will be
identified in sufficient detail to assess the impacts on
the configuration caused by the change in flow. Other
observations of river regime will be made that include:
o flow obstructions,
o characteristics of side channels and high water
channels,
o tributary characteristics,
o lateral migration evidence,
o bed scour, degradation, or aggradation,
o flood debris and high water marks, and
o stream geomorphology.
10-8
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Substrate observations and samples will be collected in
representative study areas for sediment transport and
fisheries habitat investigations. The shoreline bottom
material in the lake will also be evaluated for erosion
studies related to lake drawdown.
The collected data will be used t:o evaluate the physical
changes that are expected to occur in the affected river
systems resulting from the construction and operation of
the project. In addition, the collected data will be
used in conjunction with the fisheries habitat data to
obtain an assessment of the instream flow requirements
for the maintenance of the fisheries resource.
Aquatic Biology
Aquatic biological studies needed for 1982 will be
designed to fill the following data needs:
0
0
0
documentation of the aquatic ecosystem sufficient for
preparation of FERC applications exhibits and other
environmental documents;
the type and extent of impacts expected from proposed
project alternatives will be delineated and quantified
to the extent possible; and
the type and extent of measures needed to mitigate
environmental impacts will be defined.
The studies are designed to provide more detailed
information concerning the aquatic communities by
characterizing community distribution and relative
abundance of important species.
10-9
Specifically, important support organisms will be
investigated. Major taxonomie groups of macroinverte-
brate drift and benthic macroinvertebrates will be
characterized for the various habitat types. Particular
attention will be given to areas subject to change due to
project operation. The macrozooplankton, which are
extensively used by sockeye salmon juveniles will be
characterized in major sockeye salmon nursery areas.
Fish populations will be studied in detail. Both
resident and anadromous fishes will be studied to
characterize populations and habitat use. As discussed
above for support organisms, habitats and populations
subject to the greatest chage will be emphasized.
Efforts will be made to estimate the size and extent of
the fisheries and the timing of their migration.
Particular emphasis will be placed on identifying the
location of spawning areas and the size of the
escapement. Spawning and upstream migrants will be
monitored during the spawning season.
F
Migratory pathways used by both in-migrants and out-
migrants will be investigated. This will be particularly
important in assessing the potential for project related
impacts to block migratory routes and for determining
-
-
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....
-
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mitigating measures. A program of regular monitoring for -
out-migrants will be established to aid in assessing
seasonal flow requirements and evaluate the potential for
migratory pathway obstructions.
Seasonal distributions of fishes will be identified.
This is also important in evaluating seasonal instream
flow requirements and habitat use. The location of fish
overwintering sites are of particular importance to
10-10
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establish flow required to maintain this habitat. In
addition, winter water depth and water temperatures will
be measured in selected locations to evaluate whether
flow reduction could potentially cause freezing of
spawning redds or overwintering habitats. Such freezing
could have substantial adverse impacts on fish population
using these areas.
Since most project alternatives involve changes in water
level in Chakachamna Lake, the use of near shore and
mid-lake habitats will be studiedl. Potential impacts on
near shore lake trout spawning areas will be examined as
well as shoreline spawning and sockeye salmon nursery
habitat. Potential impacts to both the fish and macro-
invertebrate communities will be evaluated.
Detailed site-specifie habitat use will be investi-
gated. The physical components of the environment will
be measured in the various life stage habitats for each
of the important fish species. E:valuations of specifie
habitat characteristics that are likely to be affected by
project operation will be made. Collection of these data
will allow quantification of expected habitat loss or
gain, an assessment of the impact of project operation,
and an evaluation of flow releases and other similar
mitigative measures.
An evaluation will be made of the practicality of various
mitigative methods based upon the data collected.
10-11
10.3.3 Wildlife Biology
The terrestrial components of the Chakachamna Lake
project area will be evaluated using a technique similar
to the u.s. Fish and Wildlife Service's Habitat
Evaluation Procedures (HEP).
During the reconnaissance level investigations of 1981,
the project boundaries were established and a preliminary
determination of vegetation types was made. In the
spring of 1982, the project boundaries will be re-
evaluated based on the criteria that the study area
should include the total land and water areas where
either direct or indirect changes, due to the implement-
ation of the proposed project, could occur. Based on the
area encompassed by the potential impacts of the project,
a set of study quadrats will be established. Within each
quadrat, the frequency, density, and dominance will be
evaluated for each species of vegetation. A Bray-Curtis
community ordination will be conducted to separate the
various habitat types. These types will then be
delineated on maps and the area occupied by each type
will be calculated.
The selection of evaluation species will be based on
three criteria;
-
-
-
.llioi!iiO
-Ji
-
1W'
-
o those species that are known to be sensitive to the .J
types of changes that may occur through the
implementation of the project; -
0 those species that are important to the overall
community due to their role in nutrient cycling or
,_,
energy flows; and -
"""""
10-12 ·..,;
'-M
'-
•... ;
-
-
._
-
-
._
''-
-
,_"' ''''"'"""""" """"== -......,., ... _...,., """'"'"""'"~~,--' ---r' ,.,.,.,., ~---· ------·
o those species that ha~e habitat requirements that are
indicative of the requirements of a group of species
found in the area.
During the 1981 reconnaissance, six species where chosen
that fulfilled these criteria. However, for the 1982
investigations, the species componsition of the area will
be reevaluated and, if necessary, different species
chosen.
The next procedure that is advised under the HEP is the
development of the Habitat Suitability Indices (HSI).
Since the HSI is derived from a general model of the
habitat requirements of the species, the prediction
capabilities ofthe model when applied to specifie sites
may not be totally accurate. For this reason, the models
will be modified as needed to more accurately represent
the habitat requirements of the evaluation species.
As more detailed information becomes available concerning
the chronology and design of the project alternatives,
the change in the habitat suitability for the evaluation
species will be noted. Ordinarily, the procedure is to
project these changes over a future span of time and to
compare these forecasts with the predicted future habitat
suitability without the influences of the project.
However, since it is not possible to accurately predict
the effect of other programs (development of the Beluga
coal field, additional timber harvesting, offshore oil
development, etc.) on either the habitat or the wildlife,
there is no way to accurately assess the suitability of
the habitat witnout the influence of this project.
Therefore, subjective predictions will be based on the
assumption that this hydroelectric facility will be the
only manmade influence on the habitat.
10-13
10.3.4
In addition to eyaluating the potential impacts of the
project through the Habitat Evaluation Procedures, the
relative abundance of selected species of wildlife will
be expressed for each habitat type and a subjective
evaluation of the influence of the project on the
evaluation species and habitats will be made.
Human Resources
The 1982 Human Resources work program has four general
objectives:
o address agency and public concerns
o identify specifie project characteristics that will
impact human resources and quantify those impacts
o recommend measures to mitigate impacts
o discuss the projects contribution to the cumulative
impacts of regional development
Archaeological and Historical Resource investigations
will consist of a general reconnaissance level survey
that will provide the basis for subsequent intensive
investigations of small portions of the project. The
survey will concentrate on three general areas:
(1) The transmission line corridor-representing the
preferred route between the power bouse facility and
the Beluga Station;
(2) access roads, material borrow/disposal sites and
work camps; and
10-14
loloii;!Ï
-
w
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......
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-
-
-
-
.......,
'-"'
......
--
-
-
-
'-
-
-
,_,
'-"
·-
--~~~~--~~~~~m-----~~~~=-~ . ~~
(3) powerhouse facility.
Field work will include foot traverse over areas to be
surveyed and limited subsurface testing (small test pits)
in areas considered to have high potential. If
identified prior to the field survey, it is possible that
sorne construction sites can receive archaeological
clearance during the 1982 season •
The Land Ownership and Land Use prograrn will concentrate
on several tasks. Land owners of specifie transmission
line, access road, and facility sites will be identified
and contacted. Land management and use conflicts will be
quantified with mitigation measures recommended.
Finally, permit requirements for site use will be
addressed.
The Recreation program will atternpt to gather information
on recreation use levels in areas affected by the
project. This will be done through limited field surveys
and contacts with agencies, guides and air taxi
operators. Once this data is available, impacts will be
quantified. A second area of emphasis will be to
recommend mitigation measures, particularly with regard
to Chakacharnn~ Lake.
The Socioeconornic prograrn will contain several elements.
Employment opportunities, potential population and
incarne, and infrastructure impacts will be identified.
Contacts with Cook Inlet Region Inc. (CIRI), The Tyonek
Native Corporation, Village of Tyonek, and Kenai
Peninsula Borough will request information on preferences
for local hire, workforce housin91, and infrastructure
support. As data on impacts to the
10-15
anadromous fish populations are developed, the potential
impact to the Cook Inlet commerical fishery will be
assessed.
The Transportation program will attempt to gether more
data on existing transportation systems, such as traffic
levels, facility capacities, and maintenance schedules.
The managers of the various transpot facilities will be
contacted to determine use preferences. Project trans-
portation needs and impacts will be quantified, and
mitigation measures recommended.
The Visual Resource program will classify the project
area using a Bureau of Land Management classification
-
-
system. As specifie project facilities are located, ~
impacts will be described. Specifie mitigation measures,
such as facility placement and screening, will be •.,.;
recommended.
Because of the number of resource development activities
proposed for the Tyonek area, the Chakachamna Hydro
project's contribution to regional cumulative impacts
will be discussed. Impacts on socioeconomic, trans-
portation, and land use characteristic~~ill be
~~
emphasized.
··~
\
.;;
10-16
-
w
~·
.lliiiOii
--
FIGURES
"'-'
"-
--
'._
._
Figure No.
1-1
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
4-1
'~~~------'
LIST OF FIGURES
Title
Location Map
McArthur Tunnel, Alternative A-l
McArthur Tunnel, Alternative A-2
Chakachatna Tunnel, Alternatives C and D
Power Intake, Elevation
Power Intake, Sections
McArthur Power Development, General Arrangement
Chakachatna Power Development, General Arrangement
Transmission Line, Route Location
Hydrometeorological Station Locations
4-2 Hydrometeorological Stations, Periods of Record
4-3 Chakachamna Lake, Stage -Area and Storage
4-4 Alternatives A and B -Lake Level Variations
4-5 Alternatives c and D -Lake Level Variations
5-l
5-2a
5-2b
5-3
Quaternary Geology Site Locations
Glacial and Volcanic Features in the Chakachamna--
Chakachatna Valley
Glacial and Volcanic Features in the Chakachamna--
Chakachatna Valley
Plate Tectonic Map
5-4 Major Earthquakes and Seismic Gaps in Southern
Alaska
5-5 Historie Earthquakes of all Focal Depths in the
Site Region from 1929 through 1980
5-6 Historie Earthquakes of Focal Depth Greater than
20 Miles in the Site Region from 1929 through 1980
- i -
Figure No. Title
5-7 Historie Earthquakes of Focal Depth Less than
20 Miles in the Site Region from 1929 through 1980
5-8 Seismic Geology Investigation Sequence
5-9 Map Showing Locations of Candidate Significant
Features in the Project Study Area
6-1 Approximate Boundary of Chakachamna Lake Study
Are a
6-2 Locations of Hydrologie Study Areas, Representa-
tive Locations and Channel Configuration Reach
Boundaries
6-3 Stream and Floodplain Transect on Chakachatna
River Showing Approxirnate Range of Natural Stages
6-4
6-5
6-6
6-7
6-8
6-9
6-10
6-11
6-12
6-13
6-14
6-15
6-16
Stream and Floodplain Transect on Upper McArthur
River Showing Approximate Range of Natural Stages
Stream and Floodplain Transect on McArthur River
Showing Approximate Range of Natural Stages
Hydraulic Geometry of Chakachatna River Showing
A~proximate Range of Natural Flow
Hydraulic Geometry of Upper McArthur River Showing
Approximate Range of Natural Flow
Hydraulic Geometry of McArthur River Showing Ap-
proximate Range of Natural Flow
Chakachamna Lake Bottom Profile Offshore from
Shamrock Glacier Rapids
Chilligan River and Chakachamna Lake Bottom Profiles
Electroshocking and Seine Sampling Locations
Location of Fixed Net Sets
Habitat Utilization of Chakachatna River
Sockeye Salmon Spawning Area -Chilligan River and
Kenibuna Outflow
Potential Sockeye Spawning Areas -Chakachamna Lake
Chum and Sockeye Spawning Areas -Chakachatna River
Canyon and Straight Creek
-ii -
..
~
-
.-'
\ioid
-
--------~----~------==----------------~--·--------------------------------~~~-~===~----·------------~
·-
'-"
..._
'-"
._
.....
-
Figure No.
6-17
6-18
6-19
6-20
6-21
6-22
6-23
6-24
6-24
6-24
6-24
6-24
6-24
6-25
Title
Chakachatna River Mainstern Sockeye, Churn and Pink
Salmon Spawning Areas
Lower Reaches of Chakachatna, Middle and McArthur
Rivers Showing Sand, Silt and Mud Substrates
Habitat Utilization of McArthur River
Upper McArthur River Identified Spawning Areas
McArthur River Sarnpling Sites
Designated Habitat Areas
Location of Sarnpling Quadrats in Chakacharnna Study
A rea
The Location of Habitat and Vegetative Types With-
in the Study Area -Sheet 1 o,f 6
The Location of Habitat and Vegetative Types With-
in the Study Area -Sheet 2 of 6
The Location of Habitat and Vegetative Types With·-
in the Study Area -Sheet 3 of 6
The Location of Habitat and Vegetative Types With-
in the Study Area -Sheet 4 of 6
The Location of Habitat and Vegetative Types With-
in the Study Area -Sheet 5 of 6
The Location of Habitat and Vegetative Types With-
in the Study Area -Sheet 6 of 6
The Cumulative Nurnber of Bree1ding Pairs Within the
Study Area
6-26 Nesting Locations: Ba1d Eagle Nests as of May 1980.
Trurnpeter Swan Nests as of August 1980
6-27 Current Land Ownership
6-28 Existing and Potentia1 Land Use
6-29 Existing and Proposed Transportation Facilities
8-1 Access Roads
8-2 McArthur Developrnent, Construction Schedule
8-3 Chakachatna Developrnent. Construction Schedule
-iii -
Figure No.
9-1
9-2
Title
Economie Tunnel Diameter
McArthur Tunnel Economie Length
9-3 Chakachatna Tunnel Economie Length
-iv -
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3.) VE.RT/CAL DATU41 IS MEAN
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TRANSVERSE MERCATOR PROJEC710N,
1927 NORTH AMER!CAN DATUM.
?.) SEE rivURES 3·4 AND 3·5 FOR GATE
SHAFT DETAILS AND F!6VRE 3-G FOR
SUR6E TANK, PENSTOCK AND POWER·
HOUSE GENERAL ARRANGEMENT .
5000
4000
3000
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1.) TOPOGRAPHY IS FROM USGS
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3.) VERTIC-4L DATU/-1 15 MEAN SE4 L.EVEL~
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SHAFT ,OE'TAILS AND FIGURE 3·<0 FOR
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5.) SEE FI&URES 5-4-AAID 3·7 FOR
GATé 5HAFT DErA/!_5 AIJD F16UAE
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ANO POWERHOUSE GENERAL ARRANGEMENT .
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TRA/o./5/T.IOIJ __ .,_, __ ____, l TRAAISITIOIV
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No.! DATE 1 REVISIOr>l
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
CHAKACHAMNA HYDROELECTRIC PROJECT
GATE SHAFT SECTION
SHT-1
BECHTEL CIVIL & MINERALS, INC.
SAN FRANCISCO
OESIGNED
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ALASKA POWER AUTHORITY
i ANCHORAGE, ALASKA
CHAKACHAMNA HYDROELECTRIC PROJECT
GATE SHAFT SECTIONS
SHT-2
BECHTEL CIVIL & MINERALS, INC.
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CHAKACHAMNA HYDROELECTRIC PROJECT
McARTHUR POWER DEVELOPMENT
GENERAL ARRANGEMENT
BECHTEL CIVIL & MINERALS, INC.
DESIGNED tJ
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CHAKACHAMNA HYDROElECTRIC PROJECT
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BECHTEL CIVIL & MINERALS, INC.
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1927 IJORTH 41/IERICAIJ DATUM.
3)VERTICAL DATUM 1$ MEAN LOWER
LOW WATER.
--.-------1 SNOilV~O~&rawo~ŒXH W~I~O~O~O N:OilVlS '"" , ......................... -· ·-,,.,.... .... u ....... ., ..... u••••• V tt l .... u .... "a'"" : oleu·u••• y .. """ .... " ....... ~ ........... .. IIIHU14U
If 1
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-
Chakachatna River Jun 59 Sept 72
At Lake Outlet
Matanuska River May 49 Sept 73
At Palmer 1 1
Susitna River Aug 49 Sept 80
At Gold Creek 1
Skwentna River Oct 59 Sept 80
Near Skwentna
'remp. & Precip. Aug 48 Dec 80
At Kenai
Temp. & Precip. Nov 53 Dec 80
At Anchorage 1
~ 'remp. & Precip. July 51 Dec 70
At Sparrevohn 1 l
1::::1 ~
'"Cl~ txJ
lAI t-3
l'%j 1-1 tx:l
00 H t:;l !;cl G") U.IO ~ t'"' 1950 1960 1970 1980 C:> 0
>ri G")
~ H
1 ~J ~ N C'"J c:> ê!C/) ~
H
0
!2:
Cl)
AREA IN THOUS&~DS OF ACRES
28 26 24 22 20 18 16 14 12 10 8 6 4 2 0
1260
1210
H 1160 ~ .......
~
< 1110
rr:l
(J)
>"l
0 ~ 1060 <: ..
~ ~
~~ 1010
z
0
H 960 E-t ·< :>
rr:l
H 910 rr:l
860
810
....... ~ ~ ~
r-..... ..........._
~ v ~-L ,•
--_[:y V 1
1 1 1
/ /\
/ / ~ '
CAP ~c/ v \
L
/ \ AREA
~
L "' l'..
L " >'-.. v ~r---t::=.
7600 1000 2000 3000-6000 5000 4000 7000
CAPACITY IN THOUSANDS OF ACRE-FEET
1
CHAKACHAMNA
LAKE
AREA & CAPACITY DATA
ELEV. AREA CAPACITY
M.S.L. IN ACRES ACRE FEET
'
760 0 0
765 810 2,025
770 1,300 7,300
780 2,690 27,200
800 5,670 111 ,000
20 7,320 241,000
40 8,270 397,000
60 9,2J~O 572,000
80 10;4(10 769,000
900 lL59o 988,000
20 c. -;::::l1;9QO 1,224,000
Ao: ····:r~,l~O 1,467,000
60 12' ,550 1 ,717,000
80 12,980 1,973,000
1000 13,280 2,236,000
20 13,520 2,504,000
40 13,740 1 2,776,0Cl0
60 l3 ,960 3,053,000
80 14,170 3,335,000
1100 14,390 3,620,000
20 14,620 3,910,000
40 16,100 4,218,000
42 16,780 4,250,000
60 18,250 4,572,000
80 19,900 4,953,000
1200 22,956 5,382,000
20 24,104 5,852,000
40 26,038 6,354,000
---··--------------·····--
CHAKACH.At'1NA LAKE
LAJ.<E STAGE-AREA A.."iD CAPACITY
FIGURE 4-3 j
(1
p
r
)' rn ~ z !:1 ~ 0 rn rn 1)> iU
.,
/>) _, z IJJ ,/-
P. ~ -; 1 / --~ < < rn m nr )>
(P y ;G
~
~
1
6'
lJJ
1
1
6' 1
~
1
~ 1
6"
OJ
0 1\) 0
1
1
1
1 1
!
!
1
1
1
1
!
l
LA\-<.E E:LE.VAT\ON IN FEET -0 _p. 0
.. -~
.c."' ... ~
c:---.. :~
~ --.. ..... _
<~ ~
1
'~ ~---
j
0 6' 0
-
1
r~ ~
J
i ;..::::--'
1 -z:::_ '--
!
i
---:::: ~
1 1
1
0 (b 0 J-=-~ 1
-
1
() 0
1
1
-·f'""
1
1
--
---
-
N 0 1 1 .J
~
_.::::J
-~
-~
1
~
1
_;;:>
__:J
-~~---
:::::J
i
1
1
___r+J .
1
1
'
SNOILVIRYA 1~A~1 ~XV1 a ~ 8 S~AILVt~d~L1V _j
1
1
1
1
1
1
)> p
Î !:i ..,
rn m
Al 7V
z z
~ ~ -< < rn .n JU
tJ n
0
)>
r rn z a
)>
:lJ
-'\
lfll 1> j/J
6'
N
0 0 0
1
6'1
6"
(]\
....J
6'
Ci
6\
\D
-
\0
-:-.1 0
0 1\) 0
1
LAKE ELE:.VAT\ON 1 N FEET 0 .p. 0 0 6' 0 0 Cb 0 0 0 ~ -::--------. '~ f.---1 r-----'
~ r------i
1 i
·~ -r----! i
k:::::::=: r---!
1 ---~ -r----....--
<.<. l ! __.. -1 --' ' ~ 1 ~ '
~
1 -1 --r---
..::::-r--
1 1 1 1 _::;;;;=" 1 l 1 -' -r--~
b:::::::_-r--
<"
~
1 ----' ' ~ -! v
' -~ ' .~ -'
_J...::J ---+ --r--
olt!.~ -....-
l---1
À 0
1
1
1 l
/
1
1
1
1
,, ,.
' < <'Z.>~~~r-
"
"'
"
"'
<'
•"' ~<
' '
\--'
Go0
\; ·r
"' i' \ '
EXPLANAT!ON
PLACE NAMES AND LOCATIONS WITHIN THE OUATERNARY GEOLOGY
RECONNAISSANCE AREA !NVEST!GATEO BY WOODWARD-cLYDE
CONSULTANTS OURING THE 1981 FIELD SEASON.
10 15
SCALE IN MILES
0
~
\0
{~
z>o
'!·-.
WOODWARD-CLYDE CONSULTANTS
"' . <
!"'-'.-' ;""
'\
·' \."
' '
\
\
\
\ ,,
' EURASIAN ',,
\
\
PLATE '
~
-N-
~
NOTES
1. Base map from Tarr (1974).
2. After Packer and others (1975), Beikman (1978),
Cormier (1975), Reed and Lamphere (1974),
Plafker, and others (1978).
180°
D
...
.0·.-, ... !.!NtOo'"•"'~ •• ~cl\
PACIFIC
AMERICAN PLATE
60°
PLATE
30°
WOODWARD-CLYDE CONSULTANTS
LEGE ND
j;j;j;j;~;~;~;j;j;j;j Wrangel! Block
... Relative Pacifie Plate Motion
----Plate Boundary, dashed where inferred
A 1\ A Shelf Edge Structure with Oblique Slip
----lntraplate Transform or Strike-Siip Fault
No.l OATE 1 REVISfON
AlASKA POWER AUTHORITY
AIICKOIIAGE, AI.A!IKA
CHAKACHAMNA HYDROElECT~IC PROJECT
Plate Tectonic Map
BECHTEL CIVIL & MINERAlS, INC.
SAil FRANCISCO
C::HECKtO
-'0
DRAWtNG No. 1 ~EV.
Figure 5-3
•• Il ,,.
',"'-,
NOTE
·.
'•.
.......
/
1 i
t7Q•E
151'E
/
/
~ ·-,)"' IL<·
1. Modified after Davies and House (1979)
120'W ·~· 1<(\1 \ '· t., ''k• ~·'
Y,) ' \ !:~)\
}J \\ '\v0\',;, dv \ ) -·~
\ . '
/ .
&S"H
'\/ :
. ') /.:.~
1 ,r a->j
~~~·
/' .. 1 . \/ 1 ~~·/\. 1
/ \ \ ;
/1·
!
1
140'W
WOODWARD-CLYDE CONSULTANTS
LEGE ND
01964
' ~
Location and year of major
earthquake; rupture zones
including aftershock areas
are outlined
lnferred direction of motion
of Pacifie plate
Trerich axis
Approximate transform plate
margin
Ho.l DATE 1 REVIStON
ALASKA POWER
CHAKACHAMNA HYDROELECTiliC PROJECT
Major Earthquakes and
Seismic Gaps in Southern Alaska
HECHTEl CML & MINERALS, INC.
nev.
Figure 5-4
-154.00
62-08
62.00
@ Q) rn
C9 m ~ C) ,.,m-~œ rn "U C)
SKWENTNA • rn C9 rn D (l) ŒJ C)
-153.00 -152-00 -151 .oo . !50 .oo
~ ~""" ~ 62.00
rn
rn
(l)
Q)
Cl
-$-(!)C)
rn (9
C)
•MT. STONEY Cl ŒJ
~ rn C9 rnŒl
C) (9 Grn ~ CJ mC) ~
rn rn~-~· ŒJ
C9C)
rnrncfY
• SNOWCAP MOUNTAIN
[!)
Cl C)CJ
(rylel Cl
Cl C) ClC)~~Cl
rn (l)
"lf\\\..€. RADIUS ~\J~
(l)Ü
CJ ~(l) Œ) Cl Q)(l)
(l)
.œ
MT. GERDINE
Cl
ŒJ [!)
(l)
Cl~~ Cl
Cl ~~ CJC)
rn
@ (l)"' Q) ~ C9
BELUGA LAKE
o
G
Cl
\m-[!)
Cl. C)
C9 MT. SPURR C)
Cl
C9
Q)
~<!> (9 @ (9 C9
rn
(9
Q) Q) Cl
'15rnm
rn (l) CJ
<>rr, @ Cl
C) rnrn (!)CJU ~.
Cl <> Cl
(9 Œll
Cl
(l) Ill (!)ibC)~·
C9 ffi Q) Cl
rn (Cl Cl
C)~
C9
C)
@Cl C0
M~. SUSIT~ Cl
Cl
Cl
1!\:)
Q) Q)
G rn q~~J
Cl (\cE
oŒJ?R cf) ~Cl
[!)
(l) [!) Q)
Cl(!)
GOLDPAN PEAK •
KEN/BUNA ~AM;A LAK; "
0 0 ~ FIAt ISLAND
61 .oo
60.50
+
[!)
Q) (l) .,!/
C)
C)
Cl
Cl® Cl
\ [!)
Q)
C)C)
Cl Cl
Cl rn
'\ (..J...î i!!ll (l) rn C) $
C)
rn C9 )fOCKADE LAKE
(l)
61 .oo Ç!)Q) Œ)!!l Cl
(!)Cl
C)
CJ rn (9
C) \..-~"\ m~ .J \t-\
v coOT'" C9 C)
C9 rn CJ
Q)Cl
8ŒJ [!)
Cl
TURQUOISE LAKE rn [!)Cl
Cl
C)
C)
rn
Cl
CJ rn
C) Q)
Cl
rn
[!) [!)
C)G
Q)
Cl
C)
c:ŒJC9
rn rnŒl
(!) [!)
Cl
rn rn
[!) [!) -$-C) (!)rn • !!lu
6:) REDOUBT VOLCANO !!l KALGIN ISLAND
m Cl 0 m C9
Cl
rn C)
KEN Al
Q)
(9 C9
C) C) ~
• Q) Cl
C) mW STERLING
G ~Cl
(!)
Cl
C9 (9
[!)
~
Q)
$Cl 60.50
~ Jf m \!) m +
f1"'l '-el' "' (f')J m rn Cl . C) Cl mu CJ Cl SKI LAK LAKE
"' Cl u 60.33
Cl -150 .oo ) 151 00 -150.50 1 c..., en ~1C::? nn -l!=\1 .~n -·
-~ ~-.<.V .... •VV ~lddoUU
0 5 10 15 20 Miles
E*3 &*3
FA F3 FA
WOODWARD-CLYDE CONSULTANTS 0 5 10 15 20 25 Kilometers
NOTE
LEGEND
REPBRTED MAGNITUDE
C) 8.0
u 7-0
C) 6.0
C) 5.0
(l) 4.0
C9 3.0
"' 2-8
t3 1.
No Reportee! Magnitude
INTENSITY VXII
<2> Xl
(!>x
<> iX
<:> VIII
<:> VII
0 VI
~ v
1. Magnitude symbol sizes are shown on
a continuous nonlinear scale
Ho.l DATE 1 REVIllON
ALASKA POWER
AIICHOIIAGE. AlAliKA
CHAKACHAMNA HYDROELECTRIC PROJECT
Historie Earthquakes of Ali Focal Depths
in the Site Region from 1929 Through
1980
BECHTEL CIVIL & MINERALS, INC.
111!111 fii!I!ICISCO
CHECKED -'0
OAAWtNG No. AEV.
Figure 5-5
150 50 -150.00 -15roo -153.50 -153.oo -1s2.5o -152-oo -151-50(1) -1611.oo -ti 1s2.os
62 .os 1 1 1 1 1 ~ 1 j i!l ) C)
62.00
61 .50
61 .oo
60-50
+
+
• +
Q)
C)
+C)
(1)
•MT. STONEY i!l Q)
C)i!J
CJli!l
i!l
i!l
i!l
C) i!l
(9C9
i!l "~\LE RADIUS C) (9 ~[!)
• (1)(9.
MT. GERDINE
q..Œ) +
i!l
SKWENTNA•
i!l @
+C9
(1) c®(l)
~@{!] +~{!]{!]~ (1) ct
{!](')
(1) ~
i!l
C) (')
(1) i!li!l~i!l
i!l
C). i!l
~ ~ .C)(I)
(1)
i!l i!lcfr
i!l
Q)
(1)
i!l i!l i!l (I)m~ i!l
(1) ~.
i!l Œ)
C)
(1)
C9ŒJ
ffi •
WlltQW~
~(!) (1) i!l C)(I)
i!l
i!lu ~{!]~
C)
i!l
i!l
(') i!l
C)
C)i!l+
C)
'
C) C) i!l l!l
(1) l(!)i!li!ll!l
i!l " i!l
i!l (1) i!l
"m @ i!l
c:P'-'1!'1.
i!lu
(') (')
@ l!)
i!l i!l
i!l
Œ) ~.
(') i!l(') (I)i!l
+ i!l C0 C)
+~
C)
i!l
i!l
62-00
~) 0~~
C)
~
C)
(1)
• SNOWCAP MOUNTAIN
1
(1) i!l
i!l c;t, %
'-'
i!JC9 +@
i!l
i!le (1)
.GOLDPAN PEAK
0
l 0 MT. SPURR <:l
C)
BELUGA LAKE
i!l 0~ i!l C) m
i!l
M~. SUSIT~ i!l
C) QrO=O
!!l CJ
C)
i!l
i!JC9
i!l
i!l
C)
~
i!l
Œ)
+
i!l
TURQUOISE LAKE
KEN/BUNA ~AM~A LA Ki
0
0
i!l
(I)C)
C)
C)
C)
i!l
C)
Cl [!)(9 i!l
+[!) C) +
i!l i!l
C) C)
i!l
i!l C9 ~OCKADE LAKE
Œ)
i!l
C)i!l
C)
i!l
i!l
i!l
[!)(')
C)
i!l
C)~
i!l
i!l
i!l
~
TYONEK [!)®
C) C9
FIRE ISLAND
C) (1) .,f}
i!l
• C) (')i!l (1)
i!l i!l
C)
i!l
i!l
i!l i!l C)
C) \-t-'<.
(11 i!l " ,~
u coo~ (')
C2
C)i!l
/l)(')
t!Ji!l
i!l
(')
i!l
C)
C)
Q)
C)
(1)(1)
~
0:)C)
i!l
i!l
(1)
KEN Al
{!] i!l
i!l!!l i!l • C) i!l i!l
"
C)
<!>
i!l {!Jvi!l (1)
i!l KALGIN ISLAND !!l ~
œi!l i!l i!l -$-C)Ill • REDOUBT VOLCANO
i!l C)CQ(')
i!l (1) {!]
[ :<;::)~...:.) {!]
61 .oo
C)
60-50
:fi!l ~ C) + {!J(D STERLING $ !!l
C) [!)ffi !!l (1) i!l
60.33 (1) u !!l .;. -154.00 _
153
_
50
i!l (1) !!l C9 i!JSKILAK LAKE
-153-00 -15?.<;[1 -60-33 1'1?.[1(1 -151-50 -151-00 -150.50 150-00
WOODWARD-CLYDE CONSULTANTS
0 5 10 15 20 Miles
~
EH EH F3
0 510152025 Kilometers
NOTE
LEGEND
REPBRTEO MAGNITUDE
C) 8.0
C) 7-0
C) 6-0
C) 5.0
C9 4.0
(') 3.0
"' 2-8
Œl
1-
No Reported Magnitude
INTENSITY <Y XII
<Y Xl
<>x
"' v IX
~ VIII
~ VII
<2> v l
<!> v
1. Magnitude symbol sizes are shown on
a continuous nonlinear scale
Ho.! DATE l REVISION
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
CHAKACHAMNA HYDROELECTliL~ .. PRO_JECT
Historie Earthquakes of Focal Depth
Greater Than 20 Miles in the Site
Reaion from 1929 Throuah 1980
BECHTEL CIVIL & MINERAlS, INC.
SAN FRANCISCO
CHECKEO
_,
ORAwtHGHo. REV.
Figure 5-6
62-08-154 .oo -153-50 -153-00 -152-50 --152 .oc
62-00
61 -50
61 -00
60-50
+ -$-+
• MT. STONEY
+ ç
• SNOWCAP MOUNTAIN
:+' "~~~
"' • MT. SPURR
GOLDPAN PEAK •
+
~NA LAKE
KEN/BUNA LAKE
+ +
j)
BLOCKADE LAKE
TURQUOISE LAKE
+ REDOUBT v6LCANO • -$-
$
KALGIN ISLAND
15: .so ·;._-·
!!) (l
+ Œ:· +
•SKWENTNA ~r
' (I~ 0) c:_.: [1J
[!] r.:;
(T:
"'
<'> @
::;
WILLOW•
;~.}
·•
~
MT. SUSITNA • r::
"'
FIRE ISLAN~
TYO~
"--~· ~ T
•'"ft.:
1:]
~i (è'
(!) ,~"' r,oo'~-/ (!)
"'
C)
KENAI
•STERLING
+ $ + A30 .sc
~
SKILAK LAKE l 60-33 60.33
.j, -15 4 -00 -153-50 -153-00 -'52-~r: -!5?-~n -151-00 -iS0-50 -150 ·00
WOODWARD-CLYDE CONSULTANTS
0 5 10 15 20 Miles
............ !
Eë3 F3 F3
û 5 10 î52û 25 Kilometers
NOTE
LEGEND
REPORTEO MAGNITUDE
C) 8-0
C) 7-0
C) 6-0
C) 5-0
(9 4-0
(!) 3-0
"' 2-8
t!! 1.
No Reported Magnitude
1 NT ENS 1 TY VXJI
<Y XI
<Y x
<) J x
~ VIII
<:> VII
(!) VI
<> v
1. Magnitude symbol sizes are shown on
a continuous nonlinear scale
No.! DATE ! REVISION
ALASKA POWER AUTHORITY
ANCHORAGE, ALAsKA
CHAKACHAMNA HYDROELECT_Rl~_PROJECT
Historie Earthquakes of Focal Depth Less
Than 20 Miles in the Site Region from ·
1929 Throuah 1980
BECHTEL CIVIL & MINERALS, INC.
ISAH I'I!ANCISCO
CHECKfO .,.'D
OftAWIHGNo. llEV.
Figure 5-7
REVIEW AVAILABLE
LITERA TURE
APPLY LENGTH-DISTANCE SCREENING CRITERIA
WOODWARD-CLYDE CONSULTANTS
ACQUIRE AND ANALYZE
LOW-SUN-ANGLE AER IAL PHOTOGRAPHY
REMOTE SENSING
INTERPRETATION
':;,
"·
'"\_'\
\.\ "-
"
f...
"' ~ " " + "'
EXPLANATION
--·?·
0
~
,,
i-\~f)r
·,
candidate $Îgnificant fau!t or linœment, dashed
where approximately located, dotted where
corn:œ!ed, queried where location uncertaln
orinferred
Projeet Study Area. Reconm~imnce asamnent
of surface fault rupture by Woodward-Clyde
Consultants during 1981 field seuon
Areas dîseu~ in Section 5,3.3.3
10 15
SCALE IN MILES
~a~v lpnls a~e1 ~uwe4Je~e4j
.:J.O A' .. mpunog <n.ew~ xo....tdd'if
.fr\ ..
__ ..... '
\
eH.
t
$CALE 1:250000
0
E"3 Fa
,J e
::..e?l F3 F3
-~ ..
~~,"';· '<
""--==::::::J ~
5'
:J IQLOMETERS
/
,;
-><
/
LEGEND
•7 Representative Location at which discharges
have been computed.
<:)·~ location of hydrologie study areas during
the 1981 reconnaissance
1-8--1 Approximate boundari es of reaches havi ng
B-
S-
M-
Mt-
homogeneous configuration where: \
8raided
Split
Meandering
Mountainous
.. "/
U.S.G.S.: Kenai and Tyonek
1:2:>0,000 Topos
FIGURE 6. 2
locations Of Hydrologie
Study Areas, Representative
locations, And Channel
Configuration ft·each
Boundaries
-84052.
.fJ
5
4
3
2
1
0
~ -1
~ -:-2 ........
~ -3 ~ -4tj
-5
1
-6
-7
-8
-9
-10
0
-1 u
lOO
.::.1!.
<V
<V s.. u
.fJ ·.c:
()') .,...
n::l s..
.fJ
V)
200
n::l
>, c: s.. .fJ
10 n::l
" .c: c: ()') u
:JC:n::l
O•r-~ .,... co c: n::l 0:::: .,... .c: c:
s..
<V >
>,n::lU·~ n::l
S...fJ c: n::l c: c: .-.fJ c: 0 .,... 0.. n::l .,.... u "0 .c:
:ir,_ ~·g :il jAi>proximate ~ ~ L;:: t;:: Ta Nat ur al Q 10 .c: u
300
+.> c:
<V co .
.fJ +.> uc
<V 0..
Ill
C:lll
IO•r-
S...C:
t-t-
400 500 600 700
DISTANCE (ft)
Approximate
Natural
l River Flow \-------lU Rang•
800 900 1000
Note: Site is located upstream of confluence with
Strai ght Creek. in Study Are a O. Transect as shown i s
looking in downstream direction.
Figure 6.3
Stream And Floodplain Transect
on Chakachatna River
Showing Approximate Range
of Natural Stages
16
14
12
10
8
-...., 6 '+--z: 4 0 ....... .....
<( 2 > w
.....1
1.1..1
0
-2
-4
-6
-8
-10
Approximate ---
1 ,;:-----Natural Q 10
0 100 200
DISTANCE (ft}
Note: Site is located upstream of confluence with
Upper Blockade Glacier Channel in St~dy Area l.
U Approximate
Range of Stage
~ for Natural
Flow
300 400
Transect as shown is looking in downstream direction.
Figure 6.4
tream and Floodplain Transect
on Upper McArthur River
Showing Approximate Range
of Natural Stages
8
7
6
5
4
-3 1
1
2
l
-3
-4
-5
-6
0
~----------------------------~---------------------------------------------------------------------------JApproximate -t----::::::::;;;:::;;::a-_...,..------,~---------J Na tura 1 Q 1 b
....,
'+--
z
0 ...... ..... cc
ô
_J w
Note: Transect is located upstream of Lower Noaukta Slough
channel confluence in Study Area P. Transect as shown is
looking in downstream direction.
500 1000
DISTANCE (ft)
1500
pproxt-
mate
atural
iver
low
r------1 ------..r'ange
2000 2500
Fioure 6.5
tream and Floodplain Transect
on McArthur River Showing
Approximate Range of
Natural Stages
1
fi q 1 1 1 1
ec-)\pr Nov Oct May Sept
Natural Range of Mean Monthly Flows
6 /
5 /
4
1 June ~---
1 Atm---Ju\y
600
500
3
DEPTH -------------------------------------------
J
+Ji
4-i
l-i 1 !
:J:I t-!
Cl' ........ t
3:1
2
1
/-
//
(
1
'/
.,.,..,.. ..... ,.,.,...-------.,... .... ------
0, 1 1 1 1 1 1 1 1 1 1 1 ., 1 1 1 1 1 1 1 1 1 1 1 1
1000 3000 '5000 . 7000
DISCHARGE (CFS)
Note: Site is located upstream of confluence with Straight Creek
in Study Area D. For transect, refer to Figure 6.3.
9000 11000
400 + 1
!
13000
Figure 6.6
Hydraulic Geometry of
Chakachatna River Showing
Approximate Range of
Natural Flow
16
15
14
-13
V') e: 12 -
>-11 1-.......
g 10
--' w 9 >
~
8
+-' 4--
:l:
1-6 0... w
Cl 5
4
3
2
1
0
~ Natural Range of Mean Monthly Flow
____ ,_,..
/
WIDTH //
;./'_/
~..,...
/""'/
/
//
(-VELOCITY
OEPTH --------------------------
,--------v,., ,.,.,.,.
1000 2000 3000
DISCHARGE ( CFS)
Note: Site is located upstream of confluence with
Upper Blockade Glacier Channel in Study Area l.
For transect, refer to Figure 6.4.
~~~-------~-
4000
200
150
.fJ
l.f-
:::c
1-
0
1003
50
Figure 6.7
Hydraulic Geometry of Upper
McArthur River Showing
Approximate Range of
Natura 1 Flow
r
4..LI
(/) fZ 3 .
>-
1--......
.-1 Natural Range of Mean Monthly Flows
3000
~
u
0
-1 w _ ...... -
: ,/ ____ l.~.f.!l'L-----------
2 r ---------w1 ., __.----DTH
'<-1 -----t 1 1
1
-----r 2000 _ ~ 1 t 1 ~ ~
1-1-t / t ~ / :;;
/_/ 11000
5000 10000 15000
DISCHARGE (CFS)
Note: Site is located upstream of confluence with
Lower Noaukta Slough Channel in Study Area P.
For transect, refer to Figure 6.5.
20000 .2.5!l.O!l
Figure 6.8
Hydraulic Geometry of McArthur
iRiver Showing Approximate
Range of Natural Flow
....
-0 1 1 1 1 1 f 1 1 1 1 . 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1
-10~
-20
-30
-40
• -50 -I-LL. -60 -
d -70 1 ~ -aot Lake Bottom Profile~
LIJ -~ -90 T "-i ;
_:
~ -100
_:
LIJ
co -110
z -120 0 .......
~ -130 >
LIJ
d -140
.,.150
0
Note: Site is 1ocated in Study Area A
500 1000
DISTANCE (ft)
··~
1500
Figure 6.9
Chakachamna Lake Bottom
Profile Offshore From
Shamrock Glacier Rapids
lOt Chilligan River o ~water surface ~ ~ 1 ~ -1 o bed
z -20 0
~ -30i J ~ -40 dist. (ft)
i:l -50 1 1 1 15do 1
'
1 1 1Ôod 1 1 115bo' 1 1 '2doo' 1 1 1 2sod ' 1 13obo 1 1 1 13 oo -
10
0
-10
-20
tt: 1-30 .j.
ê5 -40 .......
c::t:
Chilligan River
s.:=:water surface
bed?
Chakachamna Lake
approx. di ~t..: :::\.. _ -=============::;:=====i
1 ake bottom profi 1 e /'
1-1-50 > -60
d -70 t dist. (ft) J
-80 3 oô ' ' '4doo1 1 1
' 45od 1
'
15o'oo' 1 1
• 5sod 1
'
1 6Ûod 1
'
165bo' ' ' 7oco
1 ~ f Chak achamna Lake . K water surf ace . 1 .
t~8. ~ :~ Il
1
30
40
50
60
70
80
90
00
20
~
4-.Jl3Q
40
ê5 50 .......
;;: 60
~ 70
LLl 80
90
~lake bottom profile
00 t dist. (ft) . , 101 1 1 1 1 1 1 1 1 ' j 1 1 1 1 1 1 1 1 1 l 1 1 1 r 1 1 1 1 1 l" 1 1 1 1 1
7000 7500 8000 8500 9000
Note: Site is located in Study Area B.
9500 10000
Figure 6.10
Chilligan River and
Chakachamna Lake
Bottom Profiles
l05üû
SUO~l~JOl 5U~LdW~S
au~as puv 5u~~J04SOJlJot3
ll. 9
s ooo'oçz: 1
s~a..l'tf 6u~tdwesQ
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~ ·~ . . ~ ~ .
'
~
:~
#-~
~ ~R>.~_-,.:-..·~:;;;;;,-:;-~ ~ 4 -!!~ ~: ~-s-
. ~
·. -.:~/:_' .. \ ~ CY-
,J ;~~~ ; '0
:~?--~-: ~
,. ... /".-:':'' -~.!
J
Slas laN
pax~~ JO UO~l~301
s Spawning Habitat \ M Migratory Pathway
N Nursery Habitat -~,
A Adult Habitat
x Identified Habitat Utilization
? Potential Habitat ~tilization
K Kok a nee Present or Patent i a 11y Present
0 More Then Se ven Samp 1 es Taken
CHAKACHATNA RIVER DRAINAGE HABITAT UTILIZATION BY SALMON AND T~OUT SPEClES.
MSED UPON SAMPLE COLLECTIONS AND OBSERVATIONS
SALMON Lake Rainbow Dolly
Pink Chum Sockeye Co ho Chinook Trout Trout V arden
s tl M A s N M A s N M À s N M A s N M A s N M A s N M A s N M A
? x ? x
x
7 ? ? ? x
? ? x x x
x
? ? ? ? ? x x
? x ? ? ? ? x
? x x K ? x x ? x
? ? ~ x K ? x x x ? x
? x x K x
? x x K ? x x x x x x
? x x K x x x x x x
.? x ? x
x x x x ? ?
x x x x
x x x x x x x x
x x x ? ? ' x x ? ? ? x ? x x x
x x x ? x x ? ? ? x ? x x x
x x ? ? x ? x x ? i ? x x x
x x x x x x ? x ? ! x ? ? ? ? ? x x x
x 1t x x x x x x
x x x x 11 x ' '1 ~x x -x r~ Habitat Utilization x x x x x ? ? ? ? ? . ? x x x ,
of Chakachatna River ? x ? ? x ? x ! ? x x ? x x x 1
? ? x x x ? ? x x x x x x
7 y x x ? x x ? 1 x x x x x x
? ? ? x ? ? ? ? ? x
\,~, ', ~; ' . '\~ ''·,, T'~
'ft 1~ J ,.,., Je i'' "SCAI...E Uf3:i&O >,, .J. . ' . ' ' ,
~f* = +:~:" ' ~. 1-:acD r
,r -":", e+,<t>s J e.ii··f ,,
'blilo' ·~
'1
0 Spawni ng Ohserved
:-• "': P.otent i a 1 S.pawni ng
.__ • .il Substrate
ü.S.G.S.: Tyonek A-8, 1-8
1:63,360 Topos
i
===== •
-N-
~
Sockeye Salmon Spawning
Area -Chilligan River
and Kenibuna Outflow
..,
/
--~
"
~-
~ / --\ /
-,_
-~-~-~4 -~~ ~~-,~·--,·--~ ~----' ---~-~~----~------~-~--~--------
-r
\_ .--·
~----;-----~~---_..:;,.,
SOIIlf: 1:63360
• t ! • ..._.
' _, 1000 --.-111000 ·.-nn
-.. &ii F+H ,.,...s&& -----esFa fii?i!!9 E+*
' .• 1 1 ! IUlOMfTfiiS
~
j
-
-,.. --~
~ ~ ~·
/
LEGEND
Spawning ! ~
ŒJ
U.S.G.S.:
Potentia1
A rea -N--
Unutilized Stream a
Tyonek A-7, A-6, l-7, B-8!1
1 :63,)60 Topos
--
FIGURE 6.15
Potential Sockeye
Spawning Areas
-Chakachamna Lake
-.:
.,.._Lake
__,-~
·x
"
LEGEND
~: .~ ...... } --\ .. -~,-~~Y/'~ ~'.--'"-.;/0---~. ~ .\ --.E\-/ ··~.·· ~.:~.
,.,;-.
"'"'-~
--~;_~
. '',·:~~ . \:S\' . . ., ~;;..,;' '>-t:_ ~~----.
~-~ \~-~/
'?''·
7'"~---··"'f~·
··---~·
..
."7'3";;,
..,..,.~
.. ~'
v'
0 Spawning Areas \
Chum and Sockeye Salmon
Spawni ng Are as~
Chakachatna River Canyon
and Straight Creek
U.S.G.S.: Tyonek A-7, A-a, 1-7, 1-8
1:63,3&0 Topos
1
' ~
.,.,--"';_ .;;z
' '• <:,
'.
' '
'·
~ *. .,
'\..
=
'·
;. ~ '-";r
' " .,
';s; 4 -.!rç
'·
7' ...,;;
·.,:
·".;
A Straiaht Creek
tlearWater Tributary .. 0 Spawning Site/ '
'!'yo~l: A-5, A--6, and
Kf'r.ai
~.
" ' .
\,
:;::
-:;.
"' "'·
.{
'-~
"
:::-:-
'-
~...:
-~
"
:
Chakachatna River
Mainstem Sockeye~ Chum
::J'hd Pink Sa 1mon -spawni ng
Sites
',
~
"'..-,..._
6u~M04S s~aA~~ ~"4lJIJN
pu~ ûlPP~W ·~u+~4~~~24J
/ '+ .....
t'.ft~ ûl~UlSqn~ ·~~
ON3931
1
·l111t"
A peeg -...... ,_ -···
s Spawning Habitat \ M Migratory Pathway
N Nursery Habitat -~,
A Adult Habitat
x Identified Habitat Utilization
?Potential Habitat Utilization
c=:> More Then Seven Samples Taken
0 Sampling Location
s
!
?
Pink Chum
tl M A s N M A s
x ? x x
? ? ? x
? ? x
? ? x
1 -X
? x
x x x
? ?
T
?
T
,.
~
!Y SALMON AND TROUT SPECIES
BASED UPON SAHPLE COLLECTIONS AND OBSERVATIONS
SALMON Lake Rainbow Dolly
Sockeye Co ho Chinook Trout Trout V arden
N M A s N M ·A s N M A s N M A s N M A s N H A
x x x x ? x x ]( x
x x x x ? ? 1 x x :< x
x x x x x x " x
x x 1 x x ? ? ? ? x ? x
.i( x x x x x Î( 1
x x x x ? x x !{ x l' Habitat Utilization x x ? x ? x x x ? x i{ x
? ? x ? x ? ? ? ? ? 1 ? ? ? of McArthur River x x x l( 1 x x j{ x
x 1 1 1 1 x l( x
x x x x ? ? x x ;( x
x x x x ? ? x x ;( x
~·~ 6u~u~vds pa~J~lUiPI
~-A~~ ~n4l~&JW ~addO
OZ. 9 3~WSI.:f
•o J. ()9t' &911
1. -y 't-Y lfh441 *'$'~'S'A •. ! !
Si!~Y pUOd ~vAii8 lUaJtddy
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(~'
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c::: ... \.) f '~ ., \ Id/ ,. ji ' o• ,, " ~. "\"'
~~
::1 ~ ï 1 '\ / .. U> @ 1"11 '·"'· t. (
!t ,, ''>< ,tl' , <~''
~·. Ci)
,;(
1"11 z
V'l c:J ~~ QI -·~. '
3
'•
-o ; s __, .....
:::5
\Cl , ,.. ,+, 1/ ~ VI ~l ,, '
-'• '"' ti;· .. r+ '\ q.~l ' ./
" (1) a. 11'1
\ ;/"
., ;'
Jt n > "1 11' r+ ,_)
:r c:
"1
,t , ..
VI ~ ..... _,,
r+ < l'b ro
(.•(
,,
'" / .\.:).
11'1 "1
VI
. ) /
',l l,'ll 1 Il
~ -o -)· \r' r , . ,/
......
::::!
\Cl
s-ea.1y· ~ pa:+~u6 ~sa() \Y
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euwe4Je~e43 u~ Sli..Apeno
ÔU~tdWt?$ JO UO~:J,t?JOl
ooo'oçzq
sle..tpeno ôu~tdwes D
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i
.~ 1:63160 • J .,. .. ----·tt!IIIO ·-~--.. • cl ., 1 4 ·---
1 Upland Alder Thicket
2 High Altitude Riparian
a Black tottenwood Riparian
4 Coastal Marsh Riparian
s Black Spruce Transitional ,/
s Resin Birch Bog +,
1 Willow Thicket Riparian ~
e Black Spruce Riparian
u.s.c.s.: ~nai D-5, D-6 and
Tyonek A-4, A-5 lt63,360 Topos
-~~
'· '''"
v
'~'
·~
3
3
3
The location Of Habitat
And Vegetative Types
Within The Study Area
sheet 1 of 6
8
1
5 ~\
""'-;.7 --~.~
< "".
0
"~
..::,.
'"
~'
'c, 6 "
._tt
<
, ~
..,r
1
2
3
1 4
5
6
7
~
High Altitude Ri1Jarian
Black Cottonwood Ri pan an
Coast a 1 MarshxRipari aR
Wi 11 ow Thi Cl< et
~ ~ ......
-3
3
·,
~
;,",
GJGJ
FIGURE 6. 24
The location Of Habitat
And Vegètative Types
Within the Study Area
sheet 2 of 6
LEGEND \ Upland Alder Thicket
2 High Altitude Riparian ,"'
J Black Cottonwood Riparian \
Coastal Marsh Riparian 4
s Black Spruce Transitional
s Resin Birch Bog
7 Wi 11 ow Thi cket Ri pari an
8
!', ~~
~
'1
'-
~
::;:-..:_-?
~/
-'" J
t ~
!l-6
3
~------
3'
The Location Of Habitat
And Vegetative Types
Within The Study Area
sheet 3 of 6
i ,..-
6~
09('1:9:t
•1,,..y J13U~ ri·s~/f:,
. 9 j.O V :+aa4S ·' eaJy Âpnls •41 u~4l~~
sadÂl_aAne+aôafl pu\t _
+•l~t'f~ J.O uont:xn attt
ue~~ed~~ 1a~J~41 MOll~M L
Boa 4J~~a u~sa~ 9
' teuo~l~sueJl a~n~ds )j::re l S g
-N-
ue~~ed~~ 4s~ew telseoJ ,. l ue ~~ed ~(t pooMuofi-OJ ~Je L9 e
ue~Jed~~ apn+~llV 46~H ~
la)j~~4l JaPLV puetdo ' ON3931
LEGEND
1 Upland Alder Thicket
2 High Altitude Riparian
3 Black Cottonwood Riparian
4 Coastal Marsh Riparian
s Black Spruce Transitional
s Resin Birch Bog
1 Willow Thicket Riparian
lil
·~i
l
1
' al t l CH~4
l
1
!
-N-
~
.Jhe Location .Of Habitat
~nd Vegetative Types
Within The Study Area
sheet 5 of 6
9 JO 9 ~ii4$
•~v Gpn+s i~l u~~+~~
S~l iA~lili6iA puy
lll~QIH JO UO~lVjQl i4l
ue~~~d~~ li~~~4l .OLll~ l
6og 4J~~& U~SiH 1
teuo~+~sue~l aJn~ds ~JtL& •
ue~~~d~H ~s~ew lllStOJ •
... 052
~! 1<42.
138
132
126
120
114
108'
":;; 102
Q) 96 th.;:
::;!: 90
ex:~ 84 ~::l +' 78+ IL. V)
OC11 72
o::.S:::. 66
w+'
~!:: 60+
::::> ...... 54 z:.S:::. +' .,.. 48+
3
-42
36+
30
24
18·
12
6
J
0
TOTAL POPULATION ··-·-..
CYGNETS --
BREEDING PAIRS ----
.. -------~
;•
/ ..
_;
/ ..
r·-• 1 • /
,. .. ---·-·
.-_,. .. ., .. ~
• .t
/
.~· / ..
,~·
/ ..--/-
/ // __ __..,.......
/// ~~-------. ......
---------,.,,.,,., ----'------
. ~· 0-1 o:2 o:a 0~ ():.5 o:.s 6'..7 -~8 o:e O:.ICJ o!t1 <>=12 o~3 0:..4 o:.15 o:.rs 0.:.11 0:.18 0-11
DISTANCE FROM COOK INLET
{miles)
Figure is based on data obtained in a 1980
USFWS survey of the Cook Inlet waterfowl refuges.
FIGURE 6.25
The Cumulative Number of
Breeding Pairs
Within the Study Area
096l lSn JO
SI SlSaM UVM$ ~a+adwnJ1
096( ÂVW
~ sv-SlS~ ~t~3 PLV&
:SUO~lV~Ol 5U~lSaM
gz·g 3<i09I.::!
OOQ'oÇ(';1 {
~Â~ pue J~u~ •·s·~·s·~
Sôl~S 5u~lS•N •t6eJ \7
DU nsaN' UV11fS 0
~ ,_ ... -
LEGEND
TtLake tl ark
~state \
~~
~ Tyonek Native Corp. ~ \
f1Tï1l Trading Bay State
~ Game Refuge
Ul] CIRI Surface and
m CIRI Subsurface
§23 CIRI Surface
r.::m t!.i!.i.î CIRI Pending Subsurface
[[[fi Kenai Peninsula
-·-13LM (Federal)
"'
Borough
' '
~
•.
,i y "' /'
Current Land Ownership
?
U.'S.<;.S. ~ Kenai ,and Tyone\t
1 :)50 ,.000 Topos !;'··
asn put1
L'~lUvlOd pue 6u~+s~x3
san~ LP•J:
UO ~ l1l:l...t00SU8..ll
pasodo...td pue 5u n,s P'l _
SW...IOJ.l8 Lct_l Hl. __ 0.
sd~...tlS ...t~y $
sa6ppg-=
Sp80l(--
S peov; pa~~dct.t4L~.····
QIOOll
A/OTES:
!.) TOPOGRAPHY 15 FROM USGS
OUAORAAIGLé MAPS
Z.)HOR!ZONTAL OR!O IS UN!VERSAL
TRAIJSVERSéi 1.-léCATOR
PR.OJEC/IOA/1 /927 A../OR.7H AlviERiCAN
OATUM.
3)VERTICAL OATUM 16 MEAN LOWER
LOW WATER.
LEGEiJD
EXIST!IJ<J, ROAO TO ôE
!IAPROVéO
Ex!ST!IJG ROAD
-----IJEI</ AC CESS ROAD
2 0 2 4 MILES ......, s;;l
SC ALE ' 1"= 2 MILES
1981 1982
DESCRIPTION
ENGINEERING
Feasibility Study
FERC License l
C~~CH&~A HYDROELECIRIC PROJECT
PROJECT SCHEDULE
JOB 14879-001
1983 1984 1985
\l7
1986
Alternatives A and B
1987
!
1
1938 1989
l
1 1
1990
November 20. 1981
1991 1992
Intake Exploration Pro gram _f:l_ f-Π1 1 : -1 1 j
1
Engineering Design , . . . 1 1 .J:f .. b ·i::f· .. ~·;-r-r~ +-tH-t-81-t--1 +-+jl-+-1 t--+-11-!-1+ )-+-11~1 If
1 1 1 1 1 1 1 1 1 l 1 1 1 1 ! . 1
'
LJ.I LLLI L! 1 1 Ï 1'!
PROCURE>!ENT -TURBINE/ GENERA TOR 1 i 1 l ' ~~ : 1 :.~~-;-r:~";~ .. --~:;:_-fqr __ ;_._·f:~rrNv_i+LJ._~ :.:_:_t· _·.·1-;•. r··. -+
1
_
1
1-r+l-+l--ill-+l +l-lli--+-l +
1
-+
1
-l,'-ll-ll·
' ----------------------+------++-+-+--+-HH-t-t-t++++++++-+1 ·+-t-++-+-t-t-t-ft-t-1 ,__,....._._!.-' _, 1 1 ,, ~J , 1 1, 1 ... _ ·'· ! , 1,. 1 ,1 ,l 1 .•• 1 , t.-l.""'k···-'-' -1-. -1-. -1-. --1-~-~·-+·-+·-+-· -+--1---+--+--+·-+--4· ~ 1 j ! 1 i 1,,, 1 i '' 1 1 1_1} 1 l._! t_.L, t_t .. _.I.,J.L .. •,,·
CONSTRUCTION , 1 .L.l,...~, ... ...._.,.._.i-l.-:--...~ 1. J,..,J,...~.J...,J......J.,...J.., 1.-1 l. 1.,,,:1,.~···'-. ,
1 i 1 1 1 î ; • • • ·.~-+~-r-~--l-\ ~ .. ) ~--.. ~ ... :~-~· '··-: "-iL.l·J:· (:r-· , , , , , 1 1 , 1 1 1 1 Hobilization and Water Sewage Plant _. · .... :::r;.o:;:..;_~~ ~.;.;. t, 1. >4 •• J..1, , __ . . ·""''~·· 1 1 l
1 ! j 1 1 1 : ; · ' ; • · i : i • . ! ! t.! .-. i ! 1 l 1 .l :,L. 1 1. l . l.-)~_: • 1 T d · B P r t d F . 1 . t ' -1 ~ · ·· ' ' . , . ; • •. --· · · ... •. ., '· , .. , •" .'·: ! ' , l .. ' 1 't' 1 • l w_Q;, ',._ ·. · · ' 1
ra l.ng ay o_ an acl.]. l.eti 1 1 J. : ; l ; ; ' ·-:--·-~ .. ~--..... _ .. -·.~·~-·~:--:··t·; .. t r_i··t·r;·~;.··Î i''ï'"I~1 1 .1.x:~~-~-1 Il 1 1 1 Il 1 1 1 1 ' 1
A.. .., t.,_. .~~ ~ '~!-"'~~" ~· ~· .. • ~· • ' • ( .. , . \~ ' ' d t ! ' r 1 1 •. } .. ., ·. . , ' ' ' 1 1 , ' j 1 1 1 1 1 1.r"' .. 1.p • .J. ._ ! ·"""·~--"'·"'"''"-...,;.-,..._._~ . ..;,.,"'..:.-~~..,._~ .. ~-·-··*• t·-~·-·r-r·'"'t"r" : . .' 1 1 1 1 1 1 1 1 ' '
! l l l l 1 1 11 : ! ' ' . . . . . . .. 1
, ', •• l r .!.,./ '· ! !_ ... ! !, ! -: .• !. ... :y,· ... :-t'-,·c~. ··• 1 1 1 1 1 '! 1 1 1 1 1 1 1 1
1 Access Roads & Camps -Intake 1 ' L '~!--:-.:::.:.:"'. ";:;','"~:t:,·.:..-;~~\·;~{~-'>:1. j~ L:r .. i }.;;ir~...L...!.....1....:! .L ~; r ... ! •.. f ... L,-.·~~ ·.,·. c. i 1
t--1 U:î 1 1 1 1 1 ' ,, 1 : .' , 1 ! • 1 . 1. ;,. _l •• 1 1 1, .•.. 1 1 1 ~ _1, 1 1<·.· ~ 'v •. i L: ! ~cc<>ss Raad~ & Camps -Downstream Tunnel ~''~ ............ "" · · ~ ' ' ' · : · · : i ! 1 1 1 1 ! 1 1 L 1 ! t 1 1 1 1· . 1 1 1 1 • • · 1 • ·1 1 · 1 1 1 • --+ : : · · · · ----~.:-:...----M--;--ilt' r:1 , , rï r ,· i' i 1 Y" 1 r-:·~ ' • ' · ~ '
Access Roads & Camps -Powerhouse
1
1 i 1 i t-ïT! 1 "1· )~f.i ,v, i 'r' ·r·, 1 ~i 1 .l ! <1 r·:i 1 1 j l'(+""·'' LL~r~:.(J~:(~~ 1 1 1 1 1 1 i l 1 1 l i 1 1 1
-..--.--..:-~ .. * --'*t· ~ ~, !'t ... ~ .. ---~~......._.~ ... ~~1' 1 * 1 1 "IT 1 1 1 1 ' t...} r~'
1 1 1 1 1 ! 1 1 ' p.. • • • • ! ' 1 1 1 -1 l . • ' • 1 Aceess Tunnels-Intake , 1 , : 1 , ; :.!·; ,1.)._1,".: 1 i..J.·! _1 !.LI. 1,1 .1. 1.1 "'t.l !kJ 1),..1~; 1
t ! ~~ r "Ir , 1 1 • :; • l"G'. 1 ; 1 1 f ... L 1 L 1 .1 1 .J. r . .1. r .. r ! 1 J 1 L t: • T
AccessTunnels-Downstream 1 LI_J._L.L.L..L~!:"t1~11,,1l,,j 'l:~-(.111 1 11.,.
1
1 :-•i·: ; .. :1}--l }·Jl .. l··+·~! Ill 111111111111
1 1 1 1 !Tl1 l i ' l ' •• '"' ' i •• 1 •• ., •. ., 1 Ac cess Tunnels -Powerhouse 1 . 1 1 j l : ; ; 1 : ; ; , , , 1 .1. 1 1 l 1 · · ( ! 1 •.• :t ( i 1 1 1 1 ~ ) i
Power Tunnel -Excavation ~' Il' 1! j 11 IJI-1' 1 11 i"'\iT'I f 1 1 1_1_1 •. 1 1 1_1 1 1.11 r--:--------------------t------t-i'H'-t-IHI-t+' -iiHI-t-il~l-+!-t-t-t---t!-t-+-1 +-l 1 1 1 ·' r 1 1 ; 1 i 1 · 1. : . : 1 ; 1 _i , : _, : , , i 1 _r 1
Power Tunnel -Concrete 1 l 1 1 1 l T"l 1 1 i i "î i 1 , .. , ·, ! Il if'"!' r ! 1 ..l ·~ i 1 1 1 1 1 1 1 hl 1 1 1 1 1 1 ! 1 i !'· 1 1 1 1 1; ~: 1! 1! •.
, 1 i 1 1 1 , 1 1 1 r 1 • r . , 1 r. 1 •. : . ' r-r .. : 1_ 1 ' . _~ 1 • , , ~ Ch b 1 1 1 1 1 ' 1 l 1 ! 1 1 i Il 1 1 ! ! î ï"r';_;~. 'TT.:1.-Jt"'TI •1L
1
1-1 1 1 1 l 1 1 ! 1 1 1 1 ! • 1 ! 1 Uppt::r Surge am er . · ! • ! ! l J ! l !l', ' 1 1 1 .
~ 1 1 1 1 1 1 1 1 ! i ! ... ~ . 1 1 --1 .. _. __ .... • 1 • Intake Ga te Shart . l
1
· !. TTr--;~1_-T.T":'· f ·1 ~--( r f '.
' i j l 1 i 1 n·-~--k T
- d L k T , 1 1 • 1 ' · . 1 ----~-.,.-~ • ., •• 1 --l-~+-t-++-!-88-±:;;blï:;J-:;;;rj-t1 Inta e unneJ. an a e ap t_ ~t fi::·t~t ;~ +1 _J~_,.:.::..u=t· .;,.vv,-'-r-• +rFHw
Powerhouse Complex 1 -~· .~,.!,_+ Ai-j _;....-:,--+.~+-+=-Ff=M~
;-1 i ; l l i 1 1 1 1 Lower Surge Chamber ; "-r ··.rr rr· r
Penstock and Manifold l ' .::~ ttt·t[.l-+-+i l-!-1 }--.Hlllf-+-1 H-11 ++li +-t-11-H-Illtilll Tailrace Tunnel Top Reading & Bench ~ 1-!
Tailrace Canal
River Training Works Ir-+-
ô, t-t r-+-
Switchyard
Transmission Line 1
r--t-+·
Demobilization and Site Restoration
î
H&CF CE-70 (3-75)
! ' ' 1
H t-·-r-
' t-t !-
+-tt-
1 1-1 hJ H i--1dJirh H +--
.1
PROJECT SCHEDULE
ALTERNATIVES A A..'ID B
FIGURES 8-2
1981
DESCRIPTION
ENGINEERING
Feasibility Study
FERC License
Exploration Program-Pioneer Road
Intake Exploration Program
Engineering Design
PROCUREMENT TURBINE/GENERATOR
CONSTRUCTION
Mobilization and Water/Sewage Plant
Trading Bay Port and Facilities
Airs trip 1 1
Access Roads & Camps -Intake & P.H.
Access Tunnels -Intake
Access Tunnels -Mile 3.5
Access Tunnels -Mile 7.5
Access Tunnels -Downstream
Access Tunnels -Powerhouse
Power Tunnel -·Excavate
Power Tunnel -Concrete
Upper Surge Chamber
Intake Gate Shaft
Intake Tunnel & Lake Tap
Powerhouse Complex
Lower Surge Chamber
Penstock and Manifold
Tailrace Tunnel Top Reading & Bench
Tailrace Canal
River Training Works
1 Switchyard
l Transmission Line
Demobilization & Site Restoration
H&CF CE-70 (3-751
1982
1 1
CHAKACHt~mA HYDROELECTRIC PROJECT
PROJECT SCHEDULE
JOB 14879-001
1983 1984 1985
E: l.>/( px. i'A '3
1 1 1
1
' 1
1) î 1)
1
1 : 1
1 1 ;
1
1 IJ
i i
1
1
1986
r-r-
1 1 1
1)
1
1
1
:
1
!J lE c.
r-
r-
:--
ALTERNATIVES C and D
1987 1988
i'""""" r-...-ir--' r-[ ti ...,.._
E1 ~E ~L s R :A fA Vh VA G
...,.._ ,....., ,.... ,....
1 1 1 1 1 1 1 1 1 1 1 1
L qi(
fCt:: il"' ~ >S rr Si
1-
1
r-r--,....
r1 1-1-1--r-;-
~ 1-1-r-r1 --,....
1 r-r--
r-[] [ ] 1 [ [
1989
r--,
1
1 1 1
E ..,; ~~
A, ~T !/ p f1L L
1
tl 0 ir
November 20, 1981
1990
--
1·
. -
1 1 1
lj, ~1 r':S
1
1
1991 1992 1
1
;
1
i
1
:
1
1
1
1
1
1
1
1
1 1 1 1 1 1 1 1 1 . 1 1
1
:11v LIA 'E
1 1
1
PROJECT SCHEDULE
ALTER...'l'ATIVES C AL"TD D
1
1
1
1
1
70
60
TOTAL COST
50
\1:1
0
...-1
:<
-{/)-40
~ 1
1 tl.) 1
1 1 1 8 1 1 1 1 1 1
...:1 ~
~ 30
E-1
~
~
20
OPTIMUM TUNNEL DIA. 25•
10
POWER LOSS COST
0
17 18 20 22 24 26 28 30
TUNNEL DIAMETER-FEET.
ECONOMIC TUNNEL DL\METD
FIGUU 9-1
~--
120
100
\0
0 .....
Il<
<l'>
1
1
80
1 Q
~ 1
fol 60
~
8
Ill
M
i 40
~
1
20
0
35
,. -...
~ ~AL~
~ GENERATED FllOM POWl R
/ LMAXJ:MUM ANNUAL roWn ~ = $88xto6
v-----\ ,.
1 .k.
. -
T v \_ -NET ANNUAL REVENUE
1
1
GENER.ATED FROM POWER
1 1 1
1 cp
/
/"OPTIMUM TUNNEL LENGTH•5.3,400'
l" -\_ -TUNNEL/POWERHOUSE OOST ,. -----..;;l' -
40 45 50 55 60 65
TUNNEL LENGTB-FT x 1000
'
-
70
1
75
MeARTHUI. TURREL
ECONOMIC LENGTH
FIGURE 9-2
120
100
"' 0
.....t
:><
<1}-
1
l':<l ~ 80
~ ~
Q
~ 1
E-1
tl) 60 0 u
l':<l
tl) ::::;,
0 ~
~ 40
p.. -....:~
l':<l
~
20
0 L-
45
,....._
-
v ~
ANNUAL REVENUE
GENERATED FROM POWER-\ ~
~v ~ OP•IMIZATION NbT POSSIBLE -TUNNEL~
LENGTH LH1ITEll BY TOPOGRAGHY AT
~ON MOUTH 1
~ 1 1 1 _\ -
NET ANNUAL REVENUE v
GENERATED?
~
~ -
-,... -,... ----,... -..... -\
\__TUNNEL/POWERHOUSE COST
-
~---·-···--
50 55 60 65 70 75 80 85
TUNNEL LENGTH-FT X 1000
CHAKACHATNA TUNNEL
ECONOMIC LENGTH
FIGURE 9-3