HomeMy WebLinkAboutAPA466SUPPLEMENT ALREPORT
HARZA..eBASCo
Susitna Joint Venture
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DOCUMENT CO~TROl
DRAFT
CONFIDENTIA.L;PRIVILEGED HORK
PRODUCT PREPARED IN AN1':L~IPA;I()N <j
OF LITIGATION;RESTRICTED
DISTRIBlTl'ION
SEPTEMBER 1983
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SUS/TNA JOINT VENTURE
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SUSITNAHYOf·"OELECTRICPROJECT
ENVIF,ONMENT AL IMPL:;:ATIONS OF .
SUSITNAPRO JEer ALTERNATIVES
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ALASKA POWER AUTHORITY a __
FCONOMIC AI'1D FINANCIAL UPDATE
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SUSITNA·.HYDROEELECTRIC PROJECT
ENVIRONMENTAL IMPLICATION
OF
SUSITNA PROJECT ALTERNATIVES
SEPTEMBER 1983
SUBMITTED BY
HARZA-EBASCO
$USITNAJOINT VENTURE
TO THE
ALASKA POWER AUTHORITY
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TABLE OF CONTENTS
INTRODUCTION
PART A -ALTERNATIVE SCHEMES FOR HYDROELECTRIC
DEVELOPMENT OF THE SUSITNA RIVER BASIN
PART B - A COMPARISON OF ENVIRONMENTAL IMPACTS
ASSOCIATED WITH ELECTRIC GENERATING
PROJECTS ALTERNATIVE TO SUSITNA HYDRO-
ELECTRIC lEVELOPMENT
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INTRODUCTION
September 1983
ENVI!ONMENTAL IMPLICATIONS
OF SUSITNA PROJECT ALTERNATIVES
Exhibit E of the FERC License Application considers all aspects of cOn-
struction and operation of the Project elS proposed in relation to prob-
able impacts on the physical,biological and social resources of the
affected region.The Project as described in Exhibit E consists of the
initial const~uction of the Watana Development with normal maximum re-
servoir elevation of 2185,followed by construction of the Devil Canyon
dam and reAervoir with nonnal maximum reservoir elevation of 1455.The
Watana Development would operate as a base load project until the Devil
Canyon Development enters operation,at which time the Devil Canyon De-
velopment would 'perate on base and the Watana development would oper'-
ate in the load following mode.
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The objective of this report is to present the environmental implica--
tions and trade-offs of the alternative development concepts considered
in the SusitnaProject Economic and Financial Update Report and in the
Review and Update of Conceptual Design Report.This report was pre-
pared in response to an August 22,1983 Power Authority dil.'ective re-
garding the need to "address the environmental trade-offs involved in
the reservoir elevation and reregulation dam issues.n The environmen-
tal implications of both the recommended design refinements to the
Project as described in the license Application and the alternative
reservoir elevation and reregulating dam issues are summarized in the
Economic and Financial Update Report.This report provides a more
detailed evaluation of the relative differences among the various al--
ternatives,but is not intended to be a comprehensive analysis of all
impacts of each of the alternatives •
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ENVIRONMENTAL IMPLICATIONS
OF
SUSITNA PROJECT ALTERNATIVES
SEPTEMBER 1983
PART A
ALTERNATIVE SCHEMES FOR
HYDROELECTRIC DEVELOPMENT OF THE
SUSITNA RIVER BASIN
A-i
TABI$OF CONTENTS
4.1 IMPACTS TO AQUATIC RESOURCES DURING PROJECT OPERATION A-35
A-6
A-I
A-6
A-7
A-IS
A-17
A-IS
A-19
A-19
A-21
A-23
Page
A-24
A-26
A-30
A-26
A-31
A-33
A-34
Area of Inundation
Borrow Material
Shorte~Construction Period
Relict Channel
Flood Control
Emergency Flows to Tsusena Creek
Other Design Changes
Reservoir Drawdowns
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.1.8
3.2.1 Load Following Operation Without Regulati.'Ll
3.2.2 Project Flows with Reregulation.Structure
4.1.1 Impact,s of Project Operation During the Open
Wa tel;Season A-36
4.1.2 Impacts of Project Operation During the Ice
Season.A-41
4.2.1 Effects of Altered Flow Regimes During Initial
Reservoir Filling A-44
4.2.2 Effects of Altered Water Quality During Ini-
tial Reservoir Filling A-47
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2.1 WATANA ALTERNAXIVES
2.2 DEVIL CANYON DEVELOPMENT
3.1 SEASONAL FLUCTUATIONS
3.2 DAILYFLUCTUATIONS
4.2 n1PACTS TO AQUATIC RESOURCES DURING INITIAL RESERVOIR
FILLING A-43
1.0 INTRODUCTION
2.0 AREA UPSTREAM OF DEVIL CANYON
3.0 DOWNS TRE.M1 FLOWS
4.0 DOWNSTREAM IMPACTS ON AQUATIC AND RIPARIAN RESOURCES
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4.3 IMPACTS TO DOWNSTREAM RIP~~IAN RESOURCES
4.4 DOWNSTREAM IMPACTS OF DAILY FLOW FLUCTUATIONS
5.0 REGIONAL SOCIOECONOMIC IMPACTS OF WATANAALTERNATIVES
Ii
A-50
A-48
Page
A--51
A-55
A-57
A--ii
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TABLE OF CONTENTS (Cont')
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4.4.1 AquC1tlcEcoaystem.Implications
4.4.2 Botanical and Wildlife Resource Implications
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Table
A-I
A-3
A-4
A-5
A-6
A-7
A-8
A-9
A-IO
LIS T OF TABLE S
Susitna River Alternative.Developments
Principal Tributary Streams Inundated by Wata.na
Reservoir
R6servoir Area and Required Clearing for Watana
Alternatives
Elevations of Identified Archaeological Sites
Dam.Fill Volumes
Construction Time and Labor Requirements
Minimum Designated With-Project Downstream Flow
Regime at Gold Creek
Average August and December With-Project Flows
at Gold Creek
Approximate Time to Fil1 Watana Reservoir at Four
Alternative Dam Heights
Construc.tion Work Force Requirements for Alterna-
tive Watana De~eIopments
A-iii
Page
A-4
A-9
A-I 0
A-13
A-1S
A-I 8
A-27
A-28
A-44
A-57
A-6 August and December Flow Durations
Project Labor Requirements
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A--iv
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Watana Reservoir Areas Under Alternative Development Con-cepts
Average Monthly Flo-ws at Gold Creek
Frequency Distribution of August and December Flows at Gold
Ct'eek-Watana Only,Year 2000,Demand.Level :D 4709 GWh
LIST OF EXHIBITS
Frequency Distribution of August and December Flows at Gold
Creek -Watana and Devil Canyon,Yea.r 2010,Dem.and Level =
5945 GWh
Frequency Distribution of August and December Flows at Gold
Creek.-,Watana and Devil Canyon,Year 2020,Demand Level =
7505 GWh
August and December Flow Duration Curves,Natural and With-
Project Conditions
Monthly Flo'W Distribution,Pre-and Post-PX'oject
A-3
A-I
A-2
A-4
A-5
A-8
A-7
Exhibit
A-9
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o Fill versus arch dam.
(;)Underground versus surface powerhouse.
A-2
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'!'he development as dE:sc:,:,',pedin the License Application,in-
clUding C1 50-foot drawdolffl and an unde.rground pbwerhouse.
o Should both developments be constructed with nc appreciable
changes in the design of project features or in the timing of
o Should facilities for four,rather than six,generat.1ng units
be constructed initially.wi th the fifth and sixth units con-
structed at some future date?
construction?
o Should the Devil Canyon Development be built prior to the
Watana Development?
o Should the project be l'lperated in the load following mode?
o Are there other viable a.lternatives to the proposed project?
o Normal maximum reservoir elevations of 2185,21DO,2000 and
1900 feet.
o Fourversu$six generating units in initial construction.
o
Fourteen alternative concepts for the Watana Development and three for
the Devil Canyon Development were evaluated in order to provide answers
to these questions.lbe alternatives for Watanawere differentiated by
various Cotn.binations of=
The three alternatives for Devil Ca~yon included;
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o .An arch dam with surfaee powerhouse.
For each development concept,alternative operational modes have been
considered.These are:
a.operating the downstream development (Devil Canyon or Watana
if Devil Canyon is not present)as bc:i.se load as described in
the license application;
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operating the entire project in a load following mode with
flows naturally at.tenuating as they proceed downstream.
b.
The characteristics of the al ternative development concepts selected
for consideration in the Economic and Financial Update Report a.re shown
in Table .A-I.The Watana Development,as described in the FERC License
Application,is included for comparison.
o The same configuration (with underground powerhouse)with
minor modifications by Harza-Ebasco (basically the removal
of the emergency spillway)and with IOO-foot reservoir draw'"
down if neeessary for power generation.
In terms of anticipatel environmental implications of the alterna-
tives,the development concepts would differentially impact the region
upstream of Devil CanYQ).~through construction and inundation effects
(e.g.,size of reservoir,construction time"labor requirements,etc.)
and will differentially affect the river downstream of Dev.!l Canyon
through different seasonal flow release,and possibly telD.perature"
patterns.
In addition to the alte.rnative development concepts for the SusitIla.
:Project listed above"seven potential design r(~J:inements to the Wa.tana
Development have also been eV'aluated from engineering,ecc>no.dc and
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10.7 4,4
WATAN.\[EVIL CAN'/ON
1900 1455
1 ,1~55 890
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160 60
150 100
fill Concrete ~rch
4 4
16 1.3 (arch)
1.9 (fiJ.l)
7 8
lR4 152
600 646
14,500 7,800
2,;46 1,100
1,675 S139
39 32
20,400 n/a
7 1 100 nla
49 50
4
25
7
184
700
44
150
fill
WATANA
2000
1,455
265
14.4
19,800
4,248
2,370
2,600
17,400
8,900
57
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41
8
184
800
fill
WATANA
2100
420
18 •.1
2,700
28,300
6,645
3,315
49
'150
1,455
13,500
11,JOO
70
a
184
885
6
55
fill
WATANA
2185
Modified
1,455
23.9
595
2,800
38,000
9,.470
3,740
54
120
12,700
11,000
83
Fill
6
62
W;i.fANA
2185
fERC
23.9
595
3,300
10
184
885
38 ,000
9,470
3,.740
54
120
1,455
12,600
11,300
103
Table A-I
SUSTINA RIVER ALTERNArnE DEVELOPt£NTS
Characteris t.ic
Construction Period (Years)
Dam Location (RM)
Dam Height (ft.)
Reservoir Area (Acres)
Total Reservoir Volume (l03AF)
Reservoir Volune (lOJAF)
River Length Inundated (miles)
Type of Dam
No.of Units
Vol ume of Dam (106cy )
Maximum Drawdown
Tailwater Elevation (at 12,000
cfs)
/t,,I
Approximate W~ter Retention Time
(days)(Total Volume +(1.9835 x
average annual flow of 8023)
Inundation of Principal Clear-
water Tributaries (steam miles)
Average August Flows (crs)!!
Average December Flows (cfs)~
MM-months to first power (xl03 )
Peak Work Force
--------!!At Gold Creek,assuroos presence of Devil Canyon Development
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o Relict channel treatment
o OUtlet facilities
Dam Foundation Exc,avation and Treatment
Eme/rge,ncY release facilities
o
o
o Dam.Configuration and.Composit.iQn
o Cofferdam and Di,'~rsion Tunnels
o Power Intake -Spillway Approach Channel
o Underground Cavern Orientation
o Power Conduits
o Spillway Structures (at.both Watana and Devil Canyon)
enviromnental viewpoints"These refinements (Category 1)have.been
incorporated into the Modified Watana 2185 Project.and included in the
etlldy of the al ternative development concepts.These refinements re-
late to:
These refinements are discussed in the report "Revie~T and Update of
Conceptual Design"(draft dated September,1983).All environmental
implica.tions of these refinements are discussed both in that report
and in subsequent sections of this environmental report e Additional
cost-saving design refinements (Category 2)still under considerat.ion
are also addressed in this report.These include:
.Several of the designtefinements (e.g",Cofferdam and Diversion Tunnel
details,Underground Cavern Orientation,etc.)have no sJ_gnificanten'"
vironmental implications and are therefore not further dis~ussed in
this report.
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2 .0 AREA UPSTREAM OF DEVIL CANYON
The dam and reservoir characteristics of the individual development
alternatives considered (four Watana,and Devil Canyon)are shown itl
Table A-I.The four alternative heights for the Wa tana site are de-
fined in terms of their normal maximum water surface elevation.The
WatanaDevelopment ~s described in the PERC License Application is also
shown for comparison.Individual reservoirs range in si2:e from 38,000
acres for the Watana 2185 Development to 7 ~BOO acres for the Devil
Canyon Reservoir.
Exhibit E of the License Application considers all aspects of project
construction and operation in relation to probable impacts on fish,
vegetation,wildlife and other resources of the project area.That
discussionis based on the Watana 2185 alternative combined with sub-
sequent construction of the Dev.il Canyon dam and reservoir.'!he fol-
lowing sections compare the differences in impac.ts if a lower maximum
normal water surface elevation is selected at theWatana site or if
other development conc.epts are selected.
2.1 WATANAALTERNATIVES
The majority of the anticip.~ted impacts on terrestrial and aquatic re-
sources resulting from tnt;construction andoperatfon of the two dam
project,as described in the1icense Applicat:ion,are related to the
first phase of development ,the Watatia 2185 dam and reservoir.The
relative impacts of the proposed Watana:llternatives are therefore com-
pared to those for the base case Watana2185 development.,;Dams with
lower normal maximum water surface elevations (2100,2000 OJ:'1900 feet)
WC)uld result in:
1)less ~rea inundated,
2)less borrow materia!needed,
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2.1.1 Area of Inundt~tion
Exhibit E identi,fies the major impact issues directly related to the
amount of area inundated by the Watana development as:
1 to 2 years shorter construction period,
more modest remedial mea.Bures ';0 seal the relict channel,
and;
less inherent capacity for flood.control and less regulation
of downstream flows.
5)
3)
4)
Table A-I and Exhibit A-I show that at reservoir elevations of 2100,
2000 or 1900 feet,the l,~ngth of the reservoir would be 5,10 and 15
mi.les shorter,respectivel~than at elevation 2185.Also the area
inundated is 26 ,48 and 6~r'ercent less,respectively,and the active
storage capacity is 11,36 and.55 percent less ,respectively,than for
the rese~.cvofr at elevation 2185.
These changes,in turn,will mod.ify the im.pacts that are described in
many sections of Exhibit E.Lower dl.:1m heights would be matched by a.
reduction in installed capacity (hut not the turbine discharge ca.pac-
ity)•Modified project ope'!'ation schedules would,in turn,result in
alterations in seasonal,and potentially weekly and daily,release
patterns and.therefore in downstream flow regimes.
~~.
Loss of grayling spawning and rearing habitat
Removal of vegetation
Loss of winter/spring m.oose and spring bear habit.at
Interference with hig game movements and potential for accidents
Inundation of Jay Creek mineral lick
Inundation of raptor nests
Impacts on other wildlife
Impacts on existing archaeologic and aesthetic resourc.es
A-7
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Unless otherwise identified,page references are to Exhibit E of
the License Application as filed,February 28,1983.
2 aI.lel Loss of grayling spawning and rearing ~j;abita.t.The l~atana
2185 reservoir will flood 54 miles of Sus.itIlaRf-ver DlB.instem habitat
and 28 miles of tributary habitat,including ten miles along Watans.
Creek,as well as portions of other tributaries.The primary long-term.
impact is theredu...i~"lon of clear water spawning habitat in thetribu-
taries that currently supports a substantial population of grayling
(estimated to be at least 15,000 in 1982).Future aquatic habitats
wi thin the reservoir area ~re not expected to support a significant
grayling population (page E-3-121).J.l In addition,some reduction
of burbot and whitefish spawning area is expected in mainstream habi-
Measures to minimize impoundment impacts would be to ~substantial1y
lower the surface elevation of the reservoir or to maintain surface
level during the embryo incubation period"(page E-3-171).It will not
be feasible to maintain constant reservoir elevations during the gray-
ling incubation period (May and June)because of the need to refill the
reservoir,but the alternative Watana developments would have substan-
tially lower reservoir surface elevations and therefore the reservoir
would inundate correspondingly fewer strealD.miles of,tributary habitat
than the 28 miles inundated by the ele.vation 2185 development (Table A-
2).Deadman,Watana,Kosina and Jay Creeks would be impacted by a re-
servoir at elevation 1900,but to a eonslderably smaller ~tent than by
reservoirs with higher maximum water surface elevations.The falls on
Deadman Cre.ek,with crest elevation of 1800 feet,would be inundated
undel:all alternatives.The mouth of Goose Creek is at an elevation of
approximately 2060 feet at its confluenc.e wi th the Susitna River and
would not be adverselY affected by the two low-er al.ternatives.The
mouth of the Oshetna River would be inundated only by the Watana 2185
development.
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A-9
4.1
28 ..0
10.4
4.6
3.6
1.1
1.9
23.9
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18.1
bl
14,4
bl
Length (miles)Inundated
by Reservoir EI.
0.7 1.2 1.7
6.1 7.7 9.2
2.2 3.2 3.9
1.7 2.3 3.0
-0.3
1900 2000 2100 2185
10.7
Elevati01a
at Conflue'nee
(feet)
1,513
1,552
1,67Q
1,700
2,060
2,110
Location
River
Mile
186.7
194.1
106.9
208.6
231.2
233.5
Stream
Total for six tributaries
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PRINCIPAL TRIBUTARY STREAMS al
I~J)ATED BY WATANARESERVOIR
al In.addition,the lower pnrtions of 39 smaller ,unnamed tributaries
will be inundated,for 0 .lt03.9 m:;'les,by all four a1 ternatives
with an additional 4,12 and 13 tributaries inundated by the ele-
vation 2000,2100 and 2185 alternatives respectively.
Other minor tributaries inundated
by Watana 2185 Development
bl Not determined at this time for smaller tributaries but expected
to be proportionately less as reservoir elevation is lowered.
Deaeman Cree\k
Watana Creek
Kosina Creek
Jay Creek
Goose Creek
Oshetna River
2.1.1.~Removal of Vegetation."Construction of the Watana Develop-
ment will result in the direct removal of vegetation within an area of
approximately 35,605 aeres (14,409 ha)covering a range of elevations
from 1400 to 2400 feet (430 to 730 m).In addition,about 5,258 acres
(2128 ha)of unvegetated areaS 'Will be inundated or developed"(page E-
3 ...225 as revised by supplemental information filed wi th FERC on July
11,1983).The total reservoit areasassoc.iated with the smaller ,proj-
ects will require correspondingly less remc/val of vegetation"Table A-
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2.1.1.3 Loss of Moose and Bear Habitat"Re.mo'Val of vegetation and
filling of the reservoir for the Watana2185 development ~ll reduce
the carrying capacity of the winter range by approximately 300 moose.
Also,tbeimpoundment zones,particularly the south-facing slopes)
are important as a $OUrCe of early sprin.g foods and as calviIlg areas
3 shows the total reservoir area a.nd the vegetated area of the reser-
voir for each of the Watana a1 ternatives.At the present tim.e,dif--
ferencesin the amount of required clearing for other project features
for the four al terna.tives at'e not in~luded in these calculations.The
Watana 2100,2000 and 1900 alternatives would result in preservation of
about 9,000,17,000 and 22,000 acres of natural vegetation,respective-
ly~with corresponding redttctions in impacts to wildlife resources and
a.esthetics.Natural vegetation that would be preserved by lower Watana
dam height$primarily consists of black spruce,white spruce,and mixed
fot'est types.
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67
1,900 -
14,500
39
3,900b!
10,600
53
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2,000
19,BOO
44
4,400b!
15,400
28
2,100
28,300
49
4,900b!
23,400
2,185
38,000a!
54
5,400b!
32,600
A...10
TableA-3
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RESERVOIR AREA AND REQUIRED
CLEARING FOR WATANA ALTERNATIVES
Assumed to be proportional to river length inundated since this is
predominately Open water.
From Exhibit A,page A-2-1,and ExhibitE,Chapter 2,page E-2-55;
based on R&M data in a letter dated May 7,1981.
al
bl
Reservoir elevation.(feet.,msl)
Reservoir area (acres)
River length inun.dated (miles)
Un'Vegetated area
Vegetated area
Per~ent reduction in required
clearing for reservoir
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2.1.1".4 Interference with Big Game Movements..Redu~tion of reservoir
area,particularly in the length of mainstem and tributary stream inun-
dated and the narrower reservoir width associated with the lower Watana
developments,will reduce.tht:magnitude of impacts on the carrying ca-
paci ty of the area for big game sp~cies..Such a reduction ~10ulda1SD
reduce the potential for interference with movements and the possibili-
ty for big game fatalities during river crossing attempts.Moose,ca-
rihou,brown and black bears,and possibly Dall sheep cross the river
in the prQjec t area.Barriers and potential for accidents would be
less at lower Watana elevations.and would not be present at some key
crossing areas due to the shorter reservoir lengths (e.g.,in the vici-
nity of Goose Creek,the Oshetna River)and along a portion of Watana.
Creek).
for moose.These zones also contain several large areas of river val-
ley bottomland with mixed spruce deciduous woodlands that may provide
critical moose habitat during years with severe winters.Brown bears
likewise make heavy spring use of the riparian vegetation and south-
facing slope habitat where they prey on moose calves and forage on new
spring vegetation and overwintered berries.The permanent loss of ha-
bitat and early spring foods in the impoundment area may cause a de-
crease in the carrying capacity of the area for brown bears •Loss of
habitat:will be most significant for black bears..A large proportion
of the acc;.eptable black bear habitat in the middle basin will be elimi-
nated.Whereas no brown bear denning habitat will be affected by the
Watana 2185 reservoir,9 of 13 identified black bear den sites in the
Watana :impoundment area will apparently be flooded.Lower reservoir
surface elevations would impact moose and bears to a correspondingly
lesser extent for each of the smaller reservoir al ternatives •For
examples,8 of the 9 black bear dens potentially flooded by Watana 2185
occur within an elevation range of 1900 to 2100 feet.Therefore,the
number of den sites actually flooded could vary from 1 to 8 depending
on the dam height and the exact elevation of the dens.
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2.1.1.6 Inundation of Raptor Nests.Reduction of reservoir elevation
may also be significant for raptors..Lowering the elevation of the
Watana reservoir would reduce or eliminate impacts to as many as two
bald eagle nests,one golden eagle nest,one gyrfalcon nest,and six
raven nests.depending on the al ternative selected and the exaet nest
elevations.Two bald eagle,five golden eagle,one goshawk,and five
raven nests would be inundated regardless of the alternative selected.
2 ..1.1.5 Inundation of Jay Creek Mfneral Li~..Partial inundation of
the Jay Creek mineral lick may negatively impact the Wat~ma Hills Dall
sheep population.With the reservoir at elevation 2185,up to 42 per-
cent of the surface area of the mineral lick would be intLnda ted by the
Watana impoundment (page E-3-512)0 This lick appears to be an impor-
tant nutrient source for the W'ataIla Hills Dall Sheep PQ'f'ulation.The
lick ex.tends from elevation 2000 to 2450,so lower elevations of the
reservoir lY.i11 inundate less of the lick area or may totally avoid it
(e.g.,at elevation 1900).
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A-12
2.1 ..1.7 Impacts on Other Wildlife.Reservoir clearing and general
ground disturbance associated wi th the Watana development will have
adverse impacts on the other spec.ies of wildlife present in the area
(pages E-3-512 to 517 and Tables E.3.149 to 158).Lower reservoir
eleva.tions with less needed clearing and general ground disturbance
would reduce construction and inundation impacts on all wildlife spe-
c.ies in the area,especially forest-inhabiting species such as many
birds,small mammals,and certain furbearers.The impact reduction
would be especially significant for tnarten which is dependent on
forest habitat and is the most economically important furbeare:;in the
reservoir vicinity.A reservoir elevation of 1900 feet would reduc.e
marten impacts substantially because only about half of the forest ha-
bitat lost wi.th the Watana 2185 project would be inundated by the lower
dam height..Areas of strea.m habitat utilized by mink and otter (both
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52
No.of SitesElevation(ft.)
1540 -1900
1920 -2000
2050 --2100
2133 --2185
2200 --2300
moderately abundant furbearers in the Watana reservoir vicinity)would
also be significantly less-affected by lower reservoir elevations.
Thus,lowering the normal maximum reservoir elevation from 2185 to
2100,2000 or 1900 would reduce the number of sites directly affected
by 2,12,and 18 respectively.These sites would remain .subject to
A-13
ELEVATIONS OF IDENTIFIED ARCHAEOLOGICAL
SITES IN THE WATANARESERVOIR AREA
Three of these sites appeal.'to be in the construction area and will
likely be impacted regardless of elevation selected..One site is lo-
cated upstream of the Oshetna River and would only be affected by the
elevation 2185 development.The relative elevations of the remaining
52 sites are shown.in Table A-4.
Table A-4
2.1.1.8 Other Impacts of Inundation.A total of 167 historic and
~......--....:
archaeological sites are discussed in the License Application..Of
these ,30 are identified as being directly affected by the Watana Dam
and impoundment (at El.2l85).Three additional sites may be affected
(one site directly and two potentially)by borrow area.ac.tivities.The
remaining 134 sites would be unaffected by possible changes in normal
maximum reservoir elevations at theWatana developm.ent..Since prepara-
tion of Exhibit E,26 a.dditional sites have been identified from the
Watana area.
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indirect impacts during both project construction and operation,how-
ever,.as discussed in Exhibit E of the License Application.
The License .Application also indicates that the Watana 2185 dam and
reservoir will inundate six structures J of which one,a lean-to for
hunting and fishing,is presently maintained for temporary use..These
six structures are located close to the river and will be affected by
the Watana Development,regardless of selected reservoir elevation.
Since the lower alternative reservoir elevations would inundatesignif....
icantly fewer aCres and stream miles than the reservoir as described in
the License Application,the lower elevation developments would pro-
gressively reduce the total magnitude of changes irt land use and re-
lated land use activities.Although development would increase the
potential for access to the area,the lower al ternatives would result
in larger areas remaining in primitfve ·'before project·'condition for
rec.reational activities including boating,fishing,hunting,and hik-
ing.It is rtotanti':1ipated that changes in the dam height or re$ervoir
level would result fa any significant modifications to the projectre-
lated facilities proposed in the Recreation.Plan.
Differences in al ternative Wa tana developtIlents will not change impac ts
to the exceptional Natural Features in the project area as identified
in Chapter 8 of the License Application.For example,Deadman Creek
Falls,which is located approximately 0.5 miles north of the Susitna
River-Deadman Creek confluence and rises to 1800 feet in elevation,
will still be inundated.Irt terms of the aes the tic qual!ty of the
reservoir <lnd the adjacent area ~as the reservoir is lowered and.the
total rtumber of river and tributary miles are reduced and the total
size of thereservoit and borrow sites decreases,increasingly larger
areas will retain their natural landscape characteristics.In parti....
cular,as the reservoir size decreases,the size of theproject....created
mudflat.s (located principally east of Deadm.an Creek and.in the area
A-14
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centered around Watana Creek)will be significantly reduced,thereby
diminishing potentially negative aesthetic effects including those re-
lated to blowing dust.Sally Lake near the mouth of Watana Creek has
a surface elevation of approximately 2050 feet and would be af'Eected
only by the 2100 and 2185 dam alternatives.
2.1.2 Borrow Material •
"Removal of floodplain gravel can cause erosion.,siltation,increased
turbidity,increased ice buildup cgused by ground water overflow,fish
entra.pm.ent.,and alteration of fish habitat"(page E-3-155).Borrow ma-
terial requirements for the Watana dam are shown in '1:11ble A-5.
Table A-5
DAM FILL VOLUMES
(Thousand cubic yards)
Development/Borrow 2185 2185
Nature of Fill Area FERC af Modified b/2100 2000 1900
Total Volume 61,800 55,100 40,600 24,900 16,400
Percent Reduction -:Llcl 26d/55dl 70d/
Impervious Fill D 8,300 7,250 5,160 3,370 2,230
Sand &Gravel/
Filters E 42,300 26,300 18,500 11,460 7,640
Rockfill from.
Quarry A 1,600 16 p OOO 10,900 3,210 580
Total Rockfill
from Excavation 9:;600 5,550 6,040 6,880 5,990
a/Project as described in the License Application.
b/Project as modified by Harza-Ebasco.
c/As compared to the project as described in the License Application.
j./As compared to the modif1.ed project.
A-I5
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t'beHarza-Eba.sco modified design for the El.2185 dam requires ten per-
ce:nt less fill material than that described in the License Application.
This is ma.inly because of reduced foundation excavation and revised de-
sign of the f:1.11 dam.Approximately 75 percent of themateria1 exca.-
vatedfrom the dam foundation could eventually be utilized .in dam con-
struction..'!'he remainder would be spoiled in the future reservoir
area.Since spoil material will be placed in the dead storage portion
of the reservoiI',no aesthetic or ather impacts are anticipated from
this disposal.
A project at elevation 2100 reduces the total volume of the dam by 26
percent as compared wi,th the modified El.2185 design.A development
at elevation 2000 reduces the.volume by 55 percent and a development
at elevation 1900 reduces the volume by 70 percent as compared with
the modified El.2185 design.
Borrow areas for the Watana dam are shown in FigureE .2 •.131 of the
Lieense Application.Borrow area E is a large alluvial fan deposit
at the confluence of Tsusena Creek wit.h the surface of the deposit
ranging in elevation from a low of 1410 feet near the river to 1700
feet against the valley walls"AI though the mined area will be re-
habili tated to provide feeding and overnntering fish habitat follow-
ing construction,same increased turbidity will doubtless occur from
the mining activities.The redueed volume of material needed from
borrow area E will tend to reduce the extent and duration of turbidity
and sedimentation .in the river downstream during construction.Also,
reduclng the volume needed from this area may reduce impacts on the
existing riparian habitat for moose and other species.
BorroW'areas A and D are located in upland areas away from,the reser-
voir.The volume of material needed for impervious fill (area D)is
progressively less at lower dam heights than that for the dam as de-
scribed in the Lieense Application.
A-16
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2.1.3 Shorter Construction Period
Erosion
:r>otenti,Jl for Oil and Hazardous Material Spills
Blasting
River Di/ersiotls
Reservoir Filling
Water Quality Changes
l.faintenance of Acc~ss and Temporary camps
Aircraft Disturbance
A-17
The volume of material needed from the rock quarry (area A)is also
considerably less at lower dam heights but,except for theEl II 1900
alternative,is greater than that for the project des~ribed in the
LicetlSe Application.This is due to a redistribution in the propor-
tion of the types of materials used in dam construction under the
modified design..The project modifications result ina reduction in
material extracted from the ri.ver (area E)and a smaller increase in
material excavated from the rock quarry (area A).This results in a
trade-off between less disturbance to aquatic and riparian habitats
through removal of the sand and gravel sustrate and less turbidity
downstream and increased disturbance to the area aro1.1nd the rock
quarrry with increased blasting and resultant dust and increased
aesthetic impact in the quarry area.
Many project impacts discussed in Exhibit E are essentially time de-
pendent in that the shorter th~construction per:tod,the les~~the cu-
mulative impc1(.:.t.Of particular conc:ern is increased hunting and fish-
ing pressure and the general disturhance to the environment that will
occur throughout the construction period.The lower dams ,w:i th less
placement offill material!)will require less time for construction ..
This,in turn,will result in a reduction of 'cumulative impact..Al-
though completion of construction would not totally eliminate some
sources of impact (e.g.access tt'J the area),impacts due to other
factors may be reduced by shorter construction times.Such factors
include:
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2.6
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2.8
3,140
2,520
2,140
1,730
1,480
Labor Requirements
tota.l,-Maximum,
thousand thousand
man-days J.ndivi duals
8
8
'7
6
5
Time to
first power
(yrs)
10
8
8
7
7
Construction
Total
(yrs)
CONSTR'UCTION TIME AND LABOR REQUIRm~~NTS
A-18
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Table A-6 shows the relationship between dam elevation.,construction
time,and labor requirements.'!be total labor requirements for the
sIi1a11~r developments are progressively less tha.n for the 2185 proj~ct
as described in the License Applicatiotl.;t Peak manpower requirements
remain essentially the same for all Harza-Ebasco designs but are less
than those originally planned.
De',elopment
TABLE A-6
An ancient channel,now filled,is present.i.n the north bank of the
Watana reservoir approximately 2,600 feet upstream of the dam.This
channel .runs from the Susitns River gorge to Tsusena Creek and repre-
sentsa potential source of leakage frOm the W'atana reservoir.The
controlling bedrock surface of the.channel is at elevatlon 1740 .!1nd
contains up to 454 feeto.f glacia.l deposits.
2185 FERC
2185 Modified
2100
2000
1900
To preserve thr~integrityo£the rim of the Watana 2185 reservoir and
to control lO$ses due to potential seepage ,a number of remedial mea-
sures arepropooedin the FERC License Application.'!bese measurl\:s
will h~ve a net result of disturbance to the vegetation and wildlife
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2.1.5 Flood Control
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A-19
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2~1.6 Emergency Flows to Tsusena Creek
Flows o£up to 120,000 cis.in exc.ess of the combined main spillway and
outlet facility ca.paci t:tes ma.y be re1\aased to Tsusens.Creek,thus pre'"
resources of that zone.For lower reservoir elevations (2100 to 1900),
aud depending on the results of future analyses of the tightness of the
overburden,needed remedial measures may be reduced resulting in less
ground disturbance than previously indicated.
The project as deseribed in the License Applicatfonincludes an emgr--
gency spillway to p3.ss flood flows in excess of 150,0000£s (recurrence
interval of less than once in 10.000 years).The emergE,i!ncyspi1l-way
will consist of a 1011g straight c.huteexcavate~in rock and leading in
the direction of Tmusena ·Creel<.An erodible fuse plug at the upstream.
end W'ill remain in place until overtopped.
The Watana 2185 project a:s described in the FERCLicense Application
is designed so that the polierho~se and outlet facili ties,plus reser-
voir storage,will have sufficient capacity to pass floods with recur-
rence intervals up to once in fifty years wi.thaut operating the main
spillway.During floods of this magnitude,the reservoir will be al-
lOwed to surcharge to elevation 2193.By containing the fifty year
flood without use of the spillW'ay structure,problf;!ms related to ni-
trogen supernaturation and resultant fish kills will be minimized.If
a lower elevation for the Watana project is considered (2100 to 1900),
project facilities will be modified (e.g.larger outlet works capacity)
so that nitrogen supersaturation of the water is avoided.Flows up to
the 1 in 50 year flood W'i1l continue to be passed without operation of
the main spill-way.Sufficient flood routing studies will be conductecl
to assure that the project can adequately meet these ct:'iteria.
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venting overtopping of the main dam under conditions approaching the
Probable ~1aximum flood (PMF)II It is estimated that flows down the
emerge:ncy spillway to Tsusena Creek would eontinua for a peI'iod of
20 da.ys under the PMF analysis..A comparable emergency spillway is
shown in the Lic~nse Application for the DevilCanyoll Development.
All Harza-Ebasco al ternatives for the lvatana site (and the revised
drawings for thel)evil Canyon Development)h.lve deleted the emergency
spillway..The main spillway for ei.~'h develolPlIlent has been increased
in capacity to handle flows up to the PMF flood ..
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Although flows in excess of 150,000 cfs have an EXtremely low frequency
of oceurrenee (once in 10,000 years)~their removal from Tsusena Creek
would remove a potent.ial source of project impact..Elimination of the
emet:gency spillway will result iIi elimination of di.rect disturbance to
approximately 60 a.cres of low shrub and black spruce vegetation (com-
mon types in the area)a)d the e:':"imina.tion of the potential for much
greater impacts to the terres trial,aqua tic.,and aesthetic resources of
the lower Tsuaena Creek area if the emergency spillway were ever used.
Discharges down th2 emergency spillway would cause major changes in the
characteristics of the lower portion of TsusenaCreek and loss of im-
portant babi ta t for moose,brown and l\lack bear:grayling and other
terrestrial and aquatic.:resources ..
A-20
Much of th~~lower portion of TiJusenaCreek would still be inundated by
flows apP·~oa.ch±ng the PMF.Without the emergency spillway,the creek
valley liO~lld be inundated by backwater from the river Without the ero....
sive force of flo'ws from the emergency spillway..This type of .inunda-
tion would result in considerably fewer lasting impacts on the area.
Elimination ,",£the emergency spillway from the Devil Canyon Develop--
ment wilY.have comparable effects to the proposed change in tr-e spill....
way at Watana.Approximately 60 acres of mixed woodland vegetc:ition
will remain undisturbed where th(;!emergency spillway would have been
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During the development and costing of project al ternatives,possible
design changes for specific project features ~re consider~d as -well as
thealternatble development concepts and operational modes.The elimi-
nation of the emergency spillway to Tsusena Creek has already been con-
sidered.Three other general changes in project design we.re also con'"
sidered that could influence project impacts.These are the possible
substitution of concrete arch dams for the fill dams at the three lower
Watana developments,modifications to the powerhouse designs including
a surface powerhouse,and modifications to the discharge facilities.
A1 though these have not been adopted at this time t the environmental
implications of these changes are considered below.Other design re-
finements discussed in the report on "Review and Upda.te of Conceptual
DI!sig'tln (e.g.orientation of underground caverns,modifications to the
cofferdam dive!'sion tunnel concept,and changes in the power condm ts)
will.ha.ve no significant effects and are not considered in this report.
c.onstructed.To this extent t aesthetic impacts at the Devil Canyon
site will be reduced..Since the emergency spillway would discharge
directly to the river t there will be no change in impacts resulting
from lts elimination.
The approach channel to the ma.in spillway is increa.sed in size to
handle the increased flows.Material excavated from this area will
be used in construction of the dam and will partially replace material
that previously would have c~ne from excavation for the dam foundation,
construction of the s.pillway and from the upland rock quarry.Much of
the excavation for the approELch channel will be below the normal reser-
voir surface (regardless of luternative)and therefore not visible fol-
lowing completion.Thus,these modifica.tions will.have no significant
impact ex:,cept possibly a.slight reduction in the amount of rock to be
excavated from the quarry.
2.1.7 Other Design Changes
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The initial installation of four rather than si~units as proposed in
the License Application would not signif.icantly alter long-term average
Elimination of the underground powerhouse would also result in the re-
moval of the powerhouse control building near the switc.hyardbut,in-
stead,require the construction of a 2,100 ft.above ground transmis-
sion line from the powerhouse at elevation 1600 to the swi tchyard at
elevation 2270.
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2.1.7 .2.Powerhouse Modifications.Replacement of the underground
powerhouse by a surface powerhouse located between the main spillway
and the dam.was considered,but not ad apt ed,fo r the lia tana al terna-
ti~Tes.The area where a surface powerhouse would be located will be
heavily disturbed even with construction of the underground powerhou.se,
so this wou.ld not be a new loss of natural vegetation.The surface
powerhouse would be designed to blend in wi.th the surrounding area
and not be unnecessarily obtrusive.
Analysis of the arch dam possibilities at the three lower Watana ele-
vations indicated,however,that this location is not suited to such
a project.Large lateral,fill dikes would be r~quired,thus losing
much of the environmental advantages of an arch dam.In all three in-
stances,the arch dam alternative was more expensive,without compen--
sating advantages.
2.1.7.1 Arch Dam vs.Fill Dam.The basie environmental difference
between a fill dam and a concrete arch dam at a given loeation is in
their construction.In general;the arch dam requires less construc--
tion time and less borrow material than a comparable fill dam.These
changes are similar to the changes previously discussed when consider-
ing lowering the normal surface elevation at the Watana development.
Reducing borrow material and construction time would both tend to re-
duce eonstructionimpact at the site.
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project:outflows"The main advantages attributed.to the last two units
are load following and spinning reserve.In view of the reduced load
gro.wth in.the Railbelt region,installation of the fifth and six.h
units may be delayed.Increased load folloTn,.ng with six units would
potentially result in much highe.r powerplant discharges (up to 21,000
cis as compared with a maximum of 14,000 cfs with only four units)and
increased flow fluctuations downs.tream.Environlllental aspects of load
following operation are discussed in Sections 3.2 .1 and 4.2 ..3 of this
report.
Each Watana alternative would have three large penstock tunnels instead
of the six individual smaller tunnels as described in the License Ap-
plication.Although the intake structure itself would be shortened
because of this ehange,rock excavation would increase because of the
curved approach channel required by the topography.Excavated material
would be used in dam construction.Following completion,much of the
excavated area would be below the reservoir surface.The net environ-
mental effect of th:f.s change following construction is minimal.
2.1 .7.3 Discharge Facilities.Except for enlargement of the main
spillway to handle the PMF and elimination of the emergency spillway
to Tsusena Creek,the project discharge facilities for all alternatives
will have essentially the same capacities as described in the License
Application.All flows with a return frequency of less than 50 years
will be passed through the turbines and/or cone valves wi.thout use of
the spill.W8Y ..
2.1.8 Reservoir Drawdowns
Normal maximum reservoir drawdown for the three lower reservoir al ter-
natives will be 150 feet as compared to 120 feet for the modified W2185
development.,Variations of this magnitude in the extent of maximum
d rawdown will not be significant.but reducing the area exposed by the
A-23
'},.
drawdown~by lowering the normal maximum elevation,will reduce adverse
effects on wildlife and their movements ..
The development remains a concrete arch dam with a 4-unit powerhouse.
The only modification is the removal of the emergency spillway)as
discussed in Section 2.1.60
From an enviromnental standpoint,impacts of the Devil Canyon Develop-
ment would be as described in the License Application.Differential
ifu.~,actsas compared to the prese.ntlyproposed development sequence
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A-24
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This development,as presently being c.onsidered,Is comparable to that
described in the License Application (m.ttimum elevation 1455).Incor-
poration of this development into the recommended project plan will not
add important differential impacts in relation to those described in
the License Application.
Design studies have included consideratio'Q.of 100 feet of drawdown in
the resel:"V'oir.To accommodate this change,the intake structure would
be redesigned to include openings at three levels rather than the two
as shown in th~License Application.Impacts on wildlife due to the
possibl~increase in drawgown are expected to be small since the canyon
in that area 1s relat:f.vely steep and narrow and not utilized by moose
and other wildlife to the same extent as areas further upstream in the
vicinity of the Watana Development •
2.2 DEVIL CANYON DEVELop~mNT
Construction of the Devil Canyon Dev~lopment prior to Watana Was consi-
dered in the economic analysis and found to be economically less favor-
able than con~tructing Watana first.Once the upstream storage capaci'"
ty of the Watana reservoir is developed,the nevil Canyon Development
becomes a very economical project to meet increased load demands.
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would be to delay Watana.impacts for a few years.Impacts of the two
development projects would be the sam.e regardless of which was con-
structed first.
A-25
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3 .0 DOWNSTREAM FLOWS
3.1 SEASONAL FLUCTUATIONS
The SusitnaProject will be operated to maximize average energy gener-
ation while at the same time maintaining a high level of firm energy,
and meeting the specified downstream minimum flo~regime (Table A-7)..
Reservoir storage rule curves will differ for each of the alternative
development concepts (as defined by the normal maximum reservoir eleva-·
tion --2185,2100,2000,or 1900 feet --of the ~latana Development,
with or without the Devil Canyon Development)because of differences in
maximum drawdown and active storage volume of the alternatives (Table
A-I).The downstream minimum flow regime,the "Case C"scenario dis-
cussed in the License Application,is used in the c:ompar-ison of all
alternatives except as discus$ed for the ~iatana 1900 Development in the
Watana only analysis.
Average monthly flo"Ws at Gold Creek tmder natural and wi th-project cou-
di tions are shown on Exhibit A-2 with three energy demand levels for
each alternative dam height.1befirst demand level assumes a year
2000 energy demand of 4709 GWh (DOR Mean forecast as discussed in the
Economic and Financial Update Report).With th:ts demand level,only
the Watana.Development would be in operation.'!be second demand level
occurs When beth Devil Canyon and a Watana alternative are in operation
and presents flows at Gold Creek for a year 2010 energy demand of 5945
GWh.The third level presents year 2020 flows for an energy demand of
7505 GWh .In all oft'hese cases,there is no significant difference i.n
downstream flow regimt2$resulting from project operation b,.<atweei.1.the
2185 Project as described in the FERC License Application and that for
the 2185 project as mlodified in certain design characteristic:s.Only
'downstream flo"(is as ul3ed in the Harza-Ebasco Update are presented in
this report.
A-2.6
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A"'27
Table A-7
MINIMUM DESIGNATED WITH-PROJEC'l'DOWNSTREAM FL~REGnm
AT GOLD CREEK al
Flow
cfs
6000
6000
7000
0000
9000
10000
11000
21
20
19
18
17
16
15
Date
25
26
27
28
29
30
31
July Sept.
Month Flow Month Flow..-cis cfs
October 5000 April 5000
November 5000 May 6000
December 5000 June 6000
January 5000 July 6480 hi
February 5000 August 12000
March 5000 September 9300 bl
al .As discussed in the.License Application,this!the "Case C"flow
scenario,was selected as the basic project operational flow re-
gim.e considel"ing both project and environmental interests.
bl Flows change by 1000 cis per day from 6000 on July 25 to 12,000 on
August 1 and from 12,000 On September 14 to'6000 on September 21.
Downstream.flow regimes following project:construction will be altered
from natural conditions as shown in.Exhibit A-2..Under natural condi-
tions,the average August flows (.22,017 cis ave.)are 12 times the
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10,979
11,274
8,906
7,054
1,82.5
Aug .Dec.
7505GWh
12,678
13,548
17,424
20,363
22,017
9,430
9,796
9,764
7,058
1,825
5945 GWh
Aug Dec
Energy Demnd
18,436
16,050
19,020
21,057
22,017
11,146
10,689
8,697
7,802
1,825
-
4709 GWh
Aug Dec
12,680
13,755
15,900
22,017
22,017Natural
2185
2100
2000
1900
Table A·.,8
AVERAGE AUGUST AND DECEMBER
WITH-PROJECT FLOWS AT GOLD CREEK
average December flows (1825 cis)"Under with project conditions,the
flow regime is characterized by 1nc~eases in winter flows and decreases
in summer flows·.This change in seasonal floW'patterns will result
in changes to the physical characteristics of the river downstream
following project development as discussed in Section 4.0 of this re-
port.Table A-a summarizes average August and December flows for each
demand level and each altsrnative dam elevation for the Watana Devel-
opment.These months were selected for study because,under project
cortditionsas characterized by the Case C scenario,August flows will
generally be the highes t of the year and are deemed to be c·A.-i tical in
terms of salmon access to their traditional spawning areas in the reach
between Devil Canyon and Talkeetna.December poWer demands are the
highest of the year,and therefore December proj~ct outflows are·the
greatest of thp..winter season.
A-28
Watana
Ait t.\\:t"nat ive,
Depending on hath dam elevation and power demand level,average August
floW's may be dec.reased from a natural flow of 22,017 cis to l2~678 cfs
for the fully loaded two development project (year 2020 demand of
7505 GWh).Averagt.~December flows Eit'e irlcreased from a natura!flow of
1825 cfs to a range t')£7000 to 11,300 cfs.For individual years out of
II
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the 33-year period of record,a.verage monthly December flow may exceed
14,000 cfs ('Sxhibits A-3 through A-7).August flows are maintained at
a minimum of 12,000 cfs in accordance Tdth the "Case eft scenario even
though operation solely for power producti.on would have resulted in
lesiS than 12,000 cfs at Gold Creek.
Exhibits A....3 th~ough A-5 ,.Jbow the frequency distribution of August
and December floll'/sfor each dam height for each power demand level.
For the year 2000 demand (Exhi'bit A-3)and the Tvatana 2185 develop-
ment,lUlgust flows for 26 of the 33 years of simulation were the mini-
mum of 12,000 cfs as specified by the "Case e"flow regime.At lower
dam heights,the minimum flow of 12,OOOcfs occurred 16 times for the
development at 2100 and only four times at 2000.Flows greater than
15,000 cfs,the natural minimum August flow,occurred only three times
out of 33 years for 'Watana 2185,six times for the 2100 development,
and 15 times for the Watana 2000 Development..At this power demand
level,the frequency distribu.tion of August flolrls for the Watana 1900
Development was identical to the natura.!flows.Thus,the with project
frequency distribution of Augu.st flows at Gold Creek is related to the
height of the Watana dsmand the corresponding stcral':)e capacity of the
reservoir.With higher dams"the summer flows are stored fo I'winter
generation.At the lower dam heights,the sum.JD.er flows meet reservoir
storage needs in early summer and additional flows are passed through
theprojecte Hence,flows approach natural conditions-
December flows for the Watana 2185 and 2100 Development.s (4709 GWh
energy demand)would range from 10)000 to 12,aOOcfs (18 and 29 out of'
33 yea.rs,respecti'V'ely).For Watana 2000,all 33 years had flows be-
tween 8,000 and 10,000 cfs,and 30 of the 33 years had flows between
6,000 and 8,000 cfsfoJ:the Watana 1900 Development.Comp<ll'able dis-
tributions for increased energy demands are shown on Exhibits A-4 and
A-5.Under higher demand levels,the with projec.t frequency distribu-
tion of August and .December flows exhibit the same trends as discussed
A-29
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1.operating the downstream project (DevilCallYOn or Watana i£
Devil Canyon is not present)as base-load as described in the
License Applicatio"fl;
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A-SO
For each development concept (Watanaele;vati,on)studied,alternative
operational modes have been considered"These are;
for the year 2000 demand level.An alternative method of comparison is
shown in Exhibits A-6 and A-7.Monthly flow duration levels were pre-
pared for August and December for each dam height and each energy de-
Dland level.The results are shown graphically on Exhibit A-7.De--
cember flo'WS are greatly increased compared to natural conditions for
all dam heights and power demand levels.In general,December flows
are greater at greater dam heights.Convers(!ly,August flow at Gold
Creek d~crease as darn height and reset'Vofrstorage capacity increase.
Since the lower Watana Developments have less active storage capacity
(see Table A-I)and tend to fill earlier in the summer high flow sea-
son,regulation of the summer flows decreases w:f.tb lowered normal maxi-
mum.reservoir elevation.
3.2 DAILY FLUCTUATIONS
The License Application states that "Watana will.be opeL'ated asa base-
loaded plant until Devil Canyon is completed.'Ibis will produce daily
flows that are virtually constant throughout a :Z4-hour period for most
of the year"(page E-2-104)."With both Watana and Devil Canyon oper-
ating,Wa tana can be operated as a peaking plant because it will dis-
charge directly into the Devil Canyon reservoir,which will be used to
t'egulatethe flow.The peaking Of Ta1atanaW:i.11 cause a daily fluctua-
tion of less than one foot in the Devil Canyon re!servoir.Devil Canyon
will operate as a base-loaded plant for the life of the project"(page
E-2-156)•
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A-31
3.2.1 Load Following Operation Without Regulation
c~
operating the project for load following,with flows natural-
ly attenuating as they proceed downstream •
2.
1-
Under the first of these operational tnodes f downstream flows will re-
main virtually constant except for seasonal changes as discussed in
Section 3.1 and shown in Table A"'7 II Under the second operational mode,
and in the absence of a reregulating dam,proj.ect discha:rges~.and river
stage at Gold Creek,may vary on a daily cycle to follow the load de-
mand.Actual project operation may need to be a combination of base
load and load following to provide upper and lower limits on project
discharges ..
A discharge of 14,000 cfs at the Watana site in August,however,would
resu1tin a flow of approximately 17,600 cfs at Gold Creek.Since
average August discharges for the Watana 1900 })eveloptnent exceed this
flow for all three power demand scenarios and the ave:rage August dis-
In order to provide load-following capabilities a.t the Watana Develop-
ment (and eventually at Devil Canyon),project discharges may vary on
a daily c.ycle,al though average daily flows may rem.ain essentially con-
stant from one day to the next.Flow fluctuations at Gold Creek due to
load-following may be g:reate:r during the winter than during the summer.
If o111y four units are initially installed at Watana i maximum discharge
c.apacity of the Watana powe:rhou.se would be 14,000 cfs,with &.power
generation capacity of approximately 730 MW at full reservoir elevation
(i.e .•,2185 feet).If August flows were to be maintained at the power--
house discharge capa.c!ty,the total monthly generation of about 540 GHh
would exceed the total August sYl1tem energy demand of 518 GWh in the
year 2020 (DOR mean forecast).Thus,even w:lthno other system gener-
ation at that time,it is tm.like1y that full generating capacity would
be utilized at Watana during August ..
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A-32
charges for the elevation 2000 Development equal or exceed this level
for two of the three power demand.scenarios,average releases,at least
for these lowet development alternatives,would have to be maintained
at a high level whether they were discharged from the turbines or
through the discharge facilities.
t,
These flue tua tions in river stage,howev'er,represent a worst case
situation..As the fluctuating flows proceed downstream from the.ir
sout"ce)sorne attenuation of the highs and lows may occur.At this
time,it is not known how 111uch reduc.tion there will decrease the two
extremes.Since the variations between highs and lows will decrease
as the flow proceeds downstream,flows from Watana would be more at-
tenuated at Gold Creek thancompa.rable discharges frOlll Devil Canyon.
In com.parison,base loading of the Devil Cl:Lnycn Development (or Wa tana
prior to construction of Devil Canyon)Ot'development of a reregulating
dam W'ould result in virtually no fluctuations in rivet stage at Gold
Creek over long pe~iods of time_
On a tyPical winter day,the maximum turbine.discharge capacity of the
project would remain the same,but tributary inflow ~ould be reduced
and the maximum four-unit flows at Gold Creek would be approximately
14,600 cfs.Depending on water availability and project operation,
there might be little turbine discharge from the lower Watana alterna-
tives during the early morning hours,with little inflow further down-
stream.Dam height would influence the potential magnitude of daily
load-following flow fluctuations..For the Watana only,year 2000 e.ner-
gy demand scenario,average monthly project outflows decrease from
11,100 cfs fat"the 2185 development to 10,700,8.s 700 and 7,800 cfsfor
the 2100,2000,and 1900 al ternatives respectively.If maximum flows
remain the same (limited by the turbine discharge capacity)and .the
average flows decrease,minimum flows would likewise decrease,and the
potential lI)B.gnitude and duration of dailyfluctua tions would increase
for the lower dam heights.
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3 ..2.2 proje.ct Flows with Reregulating Structure
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Pre-planned,seasonal project operating rule CUrves indicate
that project releases should be increased or decreased.
All upstrea.m storage capacity is filled,and inflow exceeds
the power discharges..At this point,the project returns
essentially to run-of-river releases dictated by flows enter-
ingthe project and routed through the various developments ..
1.
Releases fl~om.the reregulating dam would vary only for the following
reasons:
If areregulating reservoir were developed as the most d()WQstream de-
velopment,project releases could be adju$ted so that flows could be
held essent:ially constant for extended periods of time and would be
changed only gradually (approximately 1,000 cfs per day)from one rate
of release to another (see Table A-])to meet:seasonal discharge re-
quirements.
AI though its function would.be to ndnimize downs tream .impac ts ,any re-
regulating facility would be new to the Susitna Project and would cre-
ate its own environmental impacts which would have to be cOftsidered II
It.
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4 .0 DOtmSTREAft ,Il-lPACTS ON'AQUATIC AND RIPARIMl RESOURCES----.--.:.-----~---~~~---....-~..------,-..:--.----."'---_.--._-
Alternative conc.~i'ts fot'tW;\SttsitnaRj"rer Hydroelectri(;Project ma)7
result:in 1.1l1pacts to downatrearD.aquatic and riparian resources that
differ f~om those d~~cr1bed iil Exhibit E of the r.icense Application.
In thil:l see,tion,the h'\?tlications ·~f al ternative dam heights for Watana
on downstremll resources C'i,t'e disc,ussed '"
'l"he discussion is organized lnto four sec.tions.In Section 4.1.dif-
ferential impacts on aquatic re~ources due to operation of the a1 teT.'na'"''"
tive Wata.na developments are diac\tssed.In Section 4.2,any additional
differential impacts that may occur during initial filling are describ-
ed.In both sections,the assumption is made that there will not be
large daily fluctuations of flows ..In Section 4.3,the implications of
large daily flow fluctuations due to load following operation are con-
sidered.Section 4.4 discusses potential impacts on downstream ripa-'
1'1an re$ources.
As discussed in Exhibit E (e.g.,page E--3-100 and p:1ge E-3--117},the
buffe.ring effect of flows from the Chulitna and Talkeetna ri'\Ters and
other tributaries entering doWttstreamof Talkeetna is ~pected to re--
duce the magnit".1de of project-related flow changes in the IQwer river.
Const!quently,the following discussions of potential impacts emphasize
the Talkeetna to Devil Canyon reach of the Susitna River where di.ffer-
ences related to the Watana alternatives would most likely be observed •
.For purposes of this report,impacts are considered to be any deviation
from natural conditions and can be ei.ther beneficial or detr~,11tental.
Also ~it isasSUDled that the greatp,:,:,the deviation from natural cone!i-
tions,the greater the impact.Given that impacts are of similar :In--
tensity,itis further assumed that impa.cts are more significant!f
they occur over a longer time period.
A-34
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A-35
in the following $ubsec.tid~,downstream :tnlpCicts asa result of 'Project
operation will be discussed first fdr the:open water or ice-free season
and then for the ie~~covered season.
In general,flows at Gold Creek under all operating regimes will be
higher than the natural conditions in the winter and will be lower
than natural conditions in the st.m1mer (see Exhibit A-2 through A-7).
These changes from natural flow cv~ditions at Gold Creek will decrease
for the lower dam h-:ights.AI tering discharge pa.tterns may have a Vel>""
r.iety of secondary impacts,including possible changes ir-downstream
flow velocities,sediment processes,wate:r:depths,ice processes,flood
frequency and groundwater processes.
As described in ExhibitE,Chapcer 3 (see pages E-3-108 to E-3-120 and
E-3-l30 to E-3-133),project operation will primarily alter downstream
flow regimes and water quality (temperature and sediment concentra··
tions).
4.1 IMPACTS TO AQUATIC RESOURCES DURING PROJECT OPERATION
The sediment concentration and turbidity of water released from the
dam will.be significantly lower than natural conditions in the summer
and slightly greater than natut'a1 conditions in the winter.Alterna."'/
tive dam heights should not appreciably ~hange the predicted turbidity
levels of outlet water.
During project operation,the major downstream water quality changes
expected to impact aquatic resources are alterations of temperature and
8uspendp,d sedilM~nts.The temperature of the outlet water during win-ter
will be higher than natural conditions for some distance downstream,
whereas summer temperatures will be near pre-project levels.
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As considered in Exhibit E,project operation may have a var.iety of
potential impacts on downstream aquatic resources during the open water
season.These .include itl1pacts on migration of adult fish,access to
spawning areas,spawning hab!ta t)incubation and emergence,rearing,
and outmigration •
A-36
4.1.1 Impacts of Projeet Operation During.the Open Water Season
Increases in rearing habitat in spring and summer could result from
the reduced velocities,turbidities and scout"Qf the substrate.Re-
duced velocities could increase rea.ring habitat in mainstem and side
channel areas since juvenile fish tend to prefer low velocity areas.
Reduced turbidities and scouring would tend to enhance rearing by im-
proving habitat conditions for benthic invertebrates ,since currently,
high turbidi ties and scouring effects apparently limit benthic produc-
tion.!his assuntes,however,that the post-project turbidi.ties 'Will
be low enough to benefi t inv'~rtebt'ates.At this time,the net gain
0'1:'loss of rearing habitat has yet to be quantified.Greater charlge
(whetherpoaitive or nega.tive)i.n habita.t should occur at higher dam
.Project operation during the open water season may result in both th~.
gain and loss of rear.ing habitat for anadromous and resident fi.sh in
the Sus1tna River (e.g ..,p.E-3-111).Losses of some rearing habitat
(e.g.,river margins,upland sloughs)will occur if depth is reduced
enough to make areas too shallow for flah to use or if cover is elimi-
nated.Reduced del1ths at the entrance to some sloughs may prevent fish
£I-om gaining access to rearing areas.At the mouths of tributaries,
backwater areas caused by the stage of the mainstem are intportant rear-
ing areas for som.e fish (e.g.,juven.ile chinook and rainboW'trout)..
Lower mainstem flows during opet'3tion in the spring and suminer could
reduce backwater effects sufficiently such that th-a availability of
thi.s type of habitat decreases.
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ADFG,1985.Synopsis of th~1982 Aqn~t:tc Studi.es and Analysis of
Fishan4 Habitat Rela.t:ionships.Susitna.Hydro Aquatic Studies.
Phase II Report.ADF&G.SuHydro Team.
A-37
heights since malnstem depths and flows are more reduced at higher dam
eleva.tions.
P.roj(!ct opercltion may also impact the ability of spawners to enter
spawning ar,.-!as in tributaries and sloughg.Access to these habitats
~a$identified as a critical issue in Exhibit E since ~any salmon spawn
in ":hese habitats <Ii In addition,some resident fish (e.g.,gra:yling and
ra.1.Iibow trout)also move into the tributaries for spawning.Prelimi...
The significant reduction in the nUmber and magnitude of floods and
high velocities that will occur as a result of project operation (e.g.,
p .E-2-156 to p.E-2-162)could have beneficial impacts,especially for
salmon.Adult salmon enter the Susitna River to spawn primarily be--
tween JU:le and September",'Ibis upstream migration is apparently rela.t--
ed to flow,since unu~ually high~low,or unstable flows can slow or
even hal t upstrf!!lm movements (ADF&G)l/.Thus J a reduction in the
magnitude and frequency of flood flows could reduce disruptions innp-
stream m:f.grations.Upstream migration may be facilitated at higher dam
heights since the greater active storage l4pacity would tend to reduce
flood flows~On the other hand,lower dam heights have higher average
flows which likewise could fa.cilitate upstream movement:provided flood
flows can ,usa be reduced.'!be net advantage of one factor over the
other is under investigation.
Project Gperati~n in the spring andst!mIJler mayhaveanimpact~on the
outmigration of juvenile anadrom.ous species since most fry and smol ts
Qutmigrate during this period..Flows during project operation should
provide sufficient depths,howev"e~J for outmigrating fish.
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A-38
Acme '3~,at flows less than 8,000 c.fs was not considered.
Trihey,W.1983.Prelindnary Assessment of Access by Spawning
Salmon into Portag~Creek and Indian River.Anc"orage,AK.Alas-
ka Power Authority.Susitna Hydro Aquatic Studie....I vol.
2/
nary analyses of access totribu:taries (Trihey 1983)Y i.ndicates ac-
cess under project operation will probably not be a problem if mainstem
flows are at or ahove8,oeD cis at Gold Cre~k..At this flow,tributary
discharge will likely provide sufficient depth to maintain access.As-
suming8,000 cfs (June to September)represents a threshold for access
to tributaries1.l,then access of tributaries by salmon woula poten-
tially-be more restricted at higher dam heights since average monthly
flows during June and JUly are more frequently less than 8,000 cfs than
for lower heights..During August and the first half Qf September all
flows exceed 8,000 cfs since the "Case e"minimum flows are greater
than that amount.
The ease of access to sloughs for adu1 t sa.lmon (primarily chum and
sockeye)also decreases under low flow conditions.Based upon preli-
minary results of ADF&G studies,access to some sloughs used for spawn-
ing becomes an increasingly greater problem as mainstem discharge de-
creases below 20,000 cis (as measured at Gold Creek)..Access problems
will potentially be most signific.ant lmder theWatana 2185 alternative
scheme since project flows during the spawning period (as indexed by
August flows)are generally the lowest of all alternatives (Exhibit A-
7);most average flows in August for the 2185 alternative are minimum
flows (i.e.,12,000 cfs).Access during operation will be less acute
at lower da.'11.he.ights because average flows would be larger.Under
natural conditions,a\Terage monthly flows for August exceed 20,000 cfs
60 percent of'the time.Comb:tning the three power demand scenarios
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(years)as typical of the life of the project,average August flows
would exceed 20,OOOcfs 56 percent of the time for a dam at El.1900,
27 percent of the time at El.2000 and 12 and 15 percent at 2100 and
2185,respecti,rely.For the higher dams,the higher August flows would
be most common shortly after completion of the Devil Canyon Dev~lrpment
(year 2010 power demand shown on Exhibit A-7)when the Project would
have the greatest flexibility in meeting both power and fishery"in-
terests.
Project operation in tha spring and summer could impact the location
and availability of spawning habitat in the mainstem,side channels,
and sloughs (e.g.,p.E-3-109).In the mainstem and the side channels,
redticed flows may have both positive and negative impacts on spawning
habitat.Although the net gain or loss of spawning habitat under post-
project flows has yet to be quantified,it Is possible there may be
little change or even an increase in mainstem and side channel spawn-
ing areas_Currently,there is.little or no spawning in the mainstem
and small amounts in the side channels ~As dam height is increased,
the frequency and magnitude.of flood flows is decreased II This PO$t-
project reduction in the magnitude and frequency of flood events may
add new side channel and mainstem spawning habitat.Pre~ently,.these
flood flows transl--_rt lar8e amounts of sediment,scoUY.'the riverbed,
and remove spawning gravel.A reduction in flood flows would reduce
these habitat di.sruptions in the mainstem and many side channels •In
addition,a reduc.tion of the sediment load of the water would,over
time ,remove interstitial silts from the streambed,thereby possibly
increasing the amount of spaw-ning substrate available.
Reduced,but more stable)water depths associated wi.th reduced flows
follo'Wing project development may-also alter the amount of available
spawning habitat in side channels.In side channels,spawning often
occurs under present conditions in small isolated areas located on the
river margins or behind velocity barriers.These areas could be lost
A-39
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at reduced flows (2 ..g.,f't'OIn dewatering)but the more stable flows
through the channel may more than compensate for this loss through
development of new spawning habitat .•
Slough spawning areas may also be impacted by reduced operational
floW'S in the summer (e.g.,page E-3-97)which result in potential
problems with access,changes in groundwater upwelling and reduced
frequency and magnitude of overtopping of the upstream berms of the
sloughs.As discussed previously,many slough spawning areas may
be inaccessible to fish due to low flows.Also,adult salmon that
spawn in sloughs appear to spawn primarily in areas with upwelling
groundwater.Consequently,if a reduction in mainstem flo-wreduces
che extent of upwelling,then the amount of sJ)&"'ming area available
could be reduced.Overtopping impacts the spawning area in sloughs,
since high overtoppingflQw6 can alter the concentration and distri-
bution of silts and fines in the spawning gravel and othet'wise impact
incubating eggs.Also,if slough overtopping was significantly reduced
under with-project conditions (Appendix E.2 ..A of the License Applica-
tion suggests that sloughs SA,9 and..21 are all overtopped to Some de-
gree at flows in excess of 26,000 cfs a.t Gold Creek),then an increase
in aquatic vegetation and siltation in sloughs could reduce the area
available for spawning.Lower dam.heights at Watana would tend to in-
crease the overtopping of sloughs as compared to the 2185 alternative.
The net effec"::>f reducing spring and summer flows in the Susitna River
would J!robably be transformation of the physical characteristics of ma-
ny habitats.By reducing overtopping and decreasing the watel:surface
elevation of the river,some side sloughs will become upland sloughs
(i.e.,not overtopped at all),some side channels would become more
like side sloughs (i.e.,reducing the frequency of overtopping),and
some mainstem areas could take on the characteristics of side channels.
Quantifying the net positive or negative effect of habitat transform.a-
tion on fish production has not yet been done.AI ternative dam he.ights
A-40
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Flow and temperature increases may have a.significanteff~ct on ice
processes1l (e .g.,location of ice front,extent of ice cover)which
may impact incubation,emergence and overwintering (See Chapter 2 of
E:xhibi t E).Under operation of Wa tana and Devil Canyon,the ice cover
in the middle river will probably form downstream of where it present-
ly forms (likely between Talkeetna and Sherman).Downstream at Tal-
keetna,ice formation will probably be delayed.At the ice front,and
for some distance upstream,the river stage will increase over natural
open water conditions,termed "staging",due to the increased resist-
ance to river flow cal.lsedby the presence of the ice front.Stage in-
creases of up to 5 to 6 feet over natura.l conditions may occur upstream
of Talkeetna (e.g.,at Gold Creek)due to the higher winter flows from
project operation.Downstream of Talkef.!tna,increased staging effects
may be limited due to the many channels available to convey water (p.
E-2-127).Immediately upstream of the ice front,staging and backwater
effects will be increased over preproject conditions due to the higher
flows.The stage in the open water reach further upstream of the ice
front would be less thai.1.the stage in the rea.ch under ice (p.E-3-134).
A-41
1/'Ib.e ac t'ltal extent of the ice cover and the sta.ging which would
result from operations can only be predicted Withde'tailed ice
simulations.'Ib.ese are currently in progress.
During fall and winter,it is expected that post-project flows,turbid-
ity,and temperature will be altered from natural conditions.The main
impact of th~se alterations mIl probably be on incubation,emergence
and overwinteting of a.nadromous and resident species.
4.1.2 Impacts of Project.Operations During the Ice SeasOn
will likely have an effect on the number of these habitat changes that
occur with fewer hab.itat transformations,and less flow stabilization
occurring at lower dam heights.
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The increased staging downstream of the ice front might prOVide more
overwintering habitat in some areas (e.g.,sidechaDl1el s)for resident
and anadrcmous species,if wetted perimeter and depths increase under
the ice as a result of increased fish could be benefited.Warmer water
temperatures upstream.of the ice front could enhance the survival of
overwintering fish by reducing mortalities associated with freezing.
In addition,the increased watet temperature upstream of the ice front
could increase the development rate for embryos (e.g.,salmon and bur-
bot)developing under the influence of the mainstream water.Early
emerging salmon fry could be adversely affected,however,if they move
dO'Wllstream too early and encountered OQC water or lack of food.
Sta.ging due to ice formation occurs under natural coDiti tions ..Asa
cOIlLSequence,berms at the upstream end of some sloughs at and down-
stream of the ice front (primarily downstream of Gold Creek)overtop,
and,cold mainstem water flows through these overtopped sloughs.Under
such circumstances,theintergravel temperatures of these sloughs may
decrease and cause the developmental rate to slow or eggs to be killed
due to thermal shock (primarily in the early stages of development).
MOI'eover,if scouring occurs when sloughs are overtopped,incubating
eggs could be destroyed..'nle net effect of reducing incubation tem-
peratures could result in delayed emerg~nce of fry and a smaller size
of fry at emerger'ce,both of which affect the fry's survival.The
higher winter floW's under project conditions,compounded by the ice
staging effects wil increase the probability or overtopping the
sloughs.At lower dam heights for the Watana Development,winter
operational flows·would be more like natural flows..Therefore j the
probability of sloughs being overtopped because of ice staging will
be less at successively lower dam heights.
A-42
LoWer dam .heights would not likely result in appreciable changes to
water temparatu:r:es in the open water reach.Flows would be reduced as
dam height decreases which may cause the ice front to move upstream;
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thus,less open wate::.-wPuld exist upstream of the ice front,but more
overwintering hab1.tat may be available under the ice cover.
4.2 IMPACT TO AQUATIC RESOURCES DURING INITIAL RESERVOIR FILLING
Chapter 3 of Exhibit E (pages Z-3-88to E-3-106 and E-3-129 to E-3-130)
describes the expected.impacts t()downstream aquatic resources result-
ing £X'otn the initial filling r"f the Watana and Devil Canyoll reservoirs.
Significant impacts to downst:tc~T!'!.aqua tic resources are not ex:pected to
result from.initial filling of the Devil Canyon reservoir (e.g.,page
E-3-133).Therefore,only differential impacts respIting from the
initial filling of the Watana reservoir alternatives are considered in
this section.
Under median flow conditions,the Watana 2185 reservoir is expected to
take three open water seasons to fill.The filling ra.te will be such
that dO~;'nstream flow requirements for resource protection are met and a
flood storage factor maintained.Table E"'3-25 of the License Applica.-
ti()n presents the increase in water surface elevation and filling rate
(ft/day)for the Watana 2185 reservoir.
Lower da.:n heights may result in shorter periods of time needed to fill
the.Wa tana reservoir.Actual filling schedules will depend 01'1 many
factors besides the siza of the dam,the ra.te at which it increases in
height ~and inflow to the reservoir.Other factors,including inflow,
being equal,however,initial reservoir filling will occur over one or
two open water seasons for the 1900 and 2000 a1 ternativeF-t.:.nd for two
or th:ree open water seasons for the 2100 an.d 2185 dev(:'Topments.j90r
example,under medium flow conditionsw1th fillj.ng beginning in May,
the 2185 and 2100 reservoir a1t~rnati\1es Will tak.e approximately twice
as long to fill as the 1900 al ternative (Tal)le A-9).In the following
subsections,itnpacts resulting from a1 tered fl()'W'S and.water quality
downstreatn during reservoir £:l.l11.ng are discussed separately.
A-43
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When Resel"Voir
will be filled
August of 3rd yr ..
May of 3rd yr ..
J1.!ne-Ju1y of 2nd yr ..
April-May of 2nd yr~
28
25
14-15
12-13
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Months to FilW
APPROXIMATE TIME TO FILL WATANA RESERVOIR
AT FOUR ALTERNATIVE DAM HEIGHTS
2185
2100
2000
1900
Dam.Heig~"'t
Alternative
These reductions may ha,ve a variety of impac ts on fisheries resources
(e.g.,page E-3-83 to E-,3-106),including effe,c ts on upstream migration
of adult salmon)access to spawning areas,spawning habitat,and rear-
ing.
A....44
Table A-9
During initial filling,essentially p.atul-a1 flows w:l.ll be discharged
during winter (November to April)..There will,however,be substantial
flow reductions in spring and summer (TableE II 3 ..26 of the License Ap-
plica.tion)0
Adul t salmon enter the Sus:1.tna River to spawn between June and Sep-
tember.As discussed in relation to operational flows,a reduc.tion
In the lI1agnitude and frequency of high flows and associated high 'Velo-
cities during those months could racil!tate the upstream migration of
adul ts.During r.eservoir filling)the effect of flow reduction 1,Jould
be most significant for the 21B5and2100 dam heights because impacts
4 ..2.1 Effects of Altered Floti Regimes During Initi~.!Reservoir Filling
1/ASsumes median flow conditions with filling beginning in May of
year One ..
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would occur over at least two years;im.pacts under the 1900 and 2000
plans wuld oceur for less than two years.
AI teration of mainstem discharge during initlal reservoir filling may
facilitate access to some new spawning areas for resident and anadro-
mOus species (e.g.p !!E-3-90)•As discussed in Exhfbi t E,access of
chinook to the area upstream of the entrance to Devil Ca.nyon (especial--
ly to Tsusena,Fog and Devils Creaks)may be facilitated by a reduction
in stream flc,';18 during the second and third years of init:tal filling
(i"e.,for the Watana 2185 al1d 2100 alternatives.)If a reregulation
dam is bull t and completed prior to filling Watana reservoir,this
possibility for movement of fish further upstream might be eliminated
depending on the location of the rereg~llation dam.
Access for adult salmon to sloughs and tributaries is apparent:}"JT in-
fluenced by mainstem discharge.Access problems will be most a(~ute
during the seconds,ummer of filling when only the proposedmirdmum
flows (i.e.,6,000 to 12,000 cfs)will be maintained at Gold cC:r~ek.
Access will be a more severe problem under the 2185 and 2100 develop-
ment alternatives since filling spans at least two spawning seaSons
and will encompass the period with the lowest flows.
In addition to influencing spa,wning migrati.ons and access to spawning
areas,reduced mainstem discharges during initial filling may impact
(both positively and negatively)the quanti.ty and.quality of spawning
habitat.In side channel areas,some spawning 'nab!tats of salmon.may
be lost due to d~watering.On the hand,new 1l1ainstem and sidechannel
spawning areas may become available for several reasons •First,ma.rty
of the habitat.disruptions (e.g.,fluctuating veloe!ties t bank gouging
associated '(rt'itlti ice breakup,ice scour)that currently limit the use of
many mainstem a:ad side chan.nel habitats will likely be diminished dur-
ing il1itial reservoir filling.Moreover,a reduction in the frequency
ofo'Vertopplng of side channel s may inerease the amount of side channel
A-45
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Overtopping of the upstream ends of sloughs can also affect the quality
of spawing habitat.A reduction in the frequency of overtopping during
initial reservoir filing could thusal ter the quality of some spawning
substrate.Slough spawning habitats would be potentially impacted at
all four dam heights.Because filling flows ar~most reduced during
the second and third filling seasons (i.e.,at the 2185 and.2100 dam
heights),more dlough habitat might be.temporarily lost at the higher
dam.heights.•
spawning,areas ~assuming there is adequate spawning substrate.By re-
ducing the frequency ofov.ertopping,many side channal s would take on
the characteristics of side sloughs which are more heavily utilized by
spawning salmon..At this time,the net impact of altering flow regimes
during initial reservoir filling 011 the availability of mains tem and
side channel habitat (i.e.,wil!more or less habita.t be available)
has not been quantified.However,impacts will occur for all four dam
heights •Impacts will occur over a longer time period (i.e.,two to
three filling seasons)for the 2185 and 2100 al ternati"'l1'es •
As considered in ExhibitE (e .g.,P.E-3-104),the reduction of spring
and summer flows during initial filling may impact rearing of anadro-
moUs and resident fish in the Susitna River.Some rearing areas (e.g.,
river margins,side channels and sloughs with high streambed eleva-
tions)tha.t are currently u.tilized m.ay be temporarily lost due toa
reduction in depth.The gt'eatest impact to most fish,especially ju'"
veniles,will occU.r if the reduction in depth also reduces or elimi-
nates the utility of cover.Lower mainstem flows may also reduce back-
water effects at tributary mouths and thus possibly reduce the avail-
ability of this habitat type for rea.ri.ng by some species (e ..g.,juve-
nile chinook).However,wil<are flow velocities deC1:'ease but sufficient
depth.food and cover occur,neW rearing area~will bec:ome available.
Thus,while the location of many rearing areas may likely change,the
amount of rearing area could stay the same or potentially increase •
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The net impact (i.e.,gain or loss)on rearing habitat bas not been
quantified at this ti1!le.Rearing habitat will be impacted at all dam
heights as a result of altered flows during initial reservoir filling.
Impacts will be greatest at the two higher dam heights (i.e.,2185 and
2100)because two to three years of impacts are involved a.s opposed to
one to two years for the two lower heights.
4.2.2 Effects of Altered Water Quality During Initial Reservoir Fill-
ing
As a result of initial filling,water quality downstream of the dam
will differ from natural condi,tions.This will principally involve
changes in suspended sediment loads and water temperature.
The sediment concentrations of water released from the reservoir during
initial filling will be greatly reduced from natural conditions.This
will be similar to the changes in turbidity discussed in the previous
section on reservoir operations.Effect of reduced turbidity during
filling will occur for one to two open water seasons for the 1900 and
2000 al ternatives and for two to three seasons for the higher al terna-
tives .•
As described in Chapter 2 of Exhibit E (p.E-2-85 to E-2-88),the major
change in downstream water tempera.ture during initial rl;servoir filling
is that temperatures during the second open water season of filling
will be reduced (1.e.,spring and summer).August temperatures during
this period.are predicted to be 5 to 6 °Cas opposed to natural tempera-
tures of 10°0"'Ibis altered temperature pa.ttern may adversely impact
juvenile a.nd adult fish.
The reduced temperature encountered by adult salmon in the Susi tna
R:f~ver upstream of 'l'alkeetna in the second season of fil.ling lIlB.y=1)
incre~se milling ~havior;2)delay migration from the lower to middle
A-47
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Changes in .flow regimes dO~'"nstream due to.project operation may result
in both changes to riparian habitat quality and quantity through al....
tered availability a.nd local distribution of early successional vege-
tation types,and to the behavioral patterns of moose and other wild-
life in the area.The most significant changes will occur "between
Gold Creek and Talkeetna SI where annual spring and summer flooding and
spring scour by ice jamswi.l1 be reduced"(E-3""249).In addition,
higher post-project winter flows 1I1aycause a widel1ing of the tnlvege-
ta.ted flood plain,including a decrease in the size of islandS (E-3-
408)•These higher winter flows,lower summer flows,lack of ice
scouring,and lack of ice cover in po.rtions of the area (depend.ing on
the severity of the winter)will alter ripe.rian proc.esses in the Devil
Canyon-Talkeetna reach of the river.Although the net result may be
improved moose habitat for 10-20 years after project generation,flow
stabilization and related streambanlt stabilization will eventua.lly
result in the decreased availability of good moose habitat along this
river reach.nte extent of vegetation changes will vary considerably
river;aDd 3)slow migration rate (p.E-3-92 and p.E-3-93).m.timate-
1y,some fish may not spawn,have poor spawning success,or select
alternative spawning areas.Anadromous and resident fish rearing in
mainstem and side channeJ habitats above Talkeetna DUly also experience
'&educed feeding activity and growth because of the reduced tempera-
tures •This impact will be confined to the second year of initial re-
slervoir filling and thus have minimal lone term impacts.Filling of
the reservoir during the second year for the 1900 and 2000 alternatives.
should be sufficient to allow operation of the multiple level release
facilities thereby avoiding most of these temperature related impacts.
Impacts will occur for the ":,85 cdternative since the release facili-
ties will not likely be operable until after the sec.ond open water
season of filling Q
4.3 IMPACTS TO DOWNSTREAM RIPARIAN RESOURCES
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along the lower reaches of the Susitna River because of the diluting
effect of tributc:ries as well as c,hanging channel morphology.
In addition to the loss of browse,the loss of riparian babi tat and
river iSlands will result in the loss of preferred calving habitat for
moose.Islands appear to be particularly good calving areas,perhaps
as a J:esul t of lo~er numbers of predators (E-3-408).Winter moose
movements (crossing the river and to and from islands)may be greatly
restricted in rea.cheswhere ice COV2r does not exist due to the pre-
sence of the project because of the hesitancy of moose to cross open
water areas during cold weather.Further downstream,the river channel
may be ice covered but suhjectto fluctuations in stage (if non-regu-
lated load-following is practiced)and therefore of broken,uneven
surface that would be difficult to cross.If any islands becam~con-
nected to the r1.ver banks due to channel alteration,their value as
ealving areas would also be decreased.
Greater winter flt.ws,and reductions in,spring and summer flows will
also affect beaver and muskrat populations downstream.Any site cur-
rentlyoccupied should still be available post-project.!1~addi,tion,
many areas now subject to freeze-out will also be available for coloni--
zati6n because winter flows will be higher than at present.The more
stable year--round flows and reduced spring and summer flooding of food
caches and other beaver structures will also result in improved down-
stream habitat for beaVer a.nd muskrat.This,in turn,m.ay have secon-
dary adverJ3e impacts on fisnery resour:ces.
As with othel:'downstream resources.the extent of impacts of the Wate.na
alternatives will be dependent on their extent of change of downstream
flow.!b,us,the lowest eleva.tion dam has the least impact in that it
most nearly l,'epresents natural or p'i:e-project c.onditions and would be
least likely to result in long-term changes to riparian habita.t.
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These downstream impact$will be further complicated if the Sus:l.tna
Project is operated o,n a load following b3sis as described in the fol-
lowing sec.tione
4.4 DOWNSTREAl1 IMPACTS OF DAILY FLOW FLUCTUATIONS
For each of the four Watana alternatives,two operatinnal scenarios
were evaluated.One of these scenarios (base load operation)results
in daily flows that are relatively stable,whereas the other scenario
(load following without reregulation),results in daily discharges
from the project that vary significantly over the day.The impacts
that ha'V'e been discussed in Sections 402,4.2 and 4,,3 have assumed a
relatively stable daily flow regime.In this section,some potential
effects of short-term flow fluctuations on dmmstream aquatic resources
are considered.
As discussed in Section 3.2,daily changes in discharge and stage are
potentially greatest for the lower dam heights during the winter.Dai-
lyflows could potentially fluctuate up to 14,OUO cfs with four units
installed at Watanaand 21,000 cfs with six units,with little release
from the project for portions of the day,while the stage at Gold Creek
m.ay fluctuate up to three to five feet under open water conditions.
During the latter part of the smnmer (August and September),daily
fluctuations at Gold Creek would be greatest (two to three feet)for
the higher Watana alt~rnatives.
At this time,all studies of potential project impacts ha.ve assumed
relatively constant discharges (maximum.change of 2000 cfs daily),at
least on a weekly basis,which was the premise on which the text of
Exhibit E was based.The results of these studies,therefore,do not
permit prediction of potential impacts due to fluctuating flows on ice
forrnat1.on,:tce staging or aquatic and riparian resources 0 On the basis
of studies of other hydroel.ectric projects)it can be hypothesized that
A-50
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significant daily fluc.tuations in flow will primarIly have negative im-
pacts on downstream aquatic resources •Positive impacts are not like-
ly ..
The enviromnental ram'Lfications of operating the Susi tna Hydroelectric
Project on a load following basis are highly dependent upon the magni-
tude discharge variations during a 24-hour period and the season in
which these variations occur.'!be most significant effects of load
following are expected to occur wi thin the aquatic ecosystem as simi-
larly encountered at other hydroelectric projects operated on a load
following or peaking basis •The effects to the terrestrial system are
primarily those which would occur within the dally inundation zone,the
associated riparian habitats along the ~iver margins,and in the flood-
plains.In addition,load following could result in potential impacts
to cultural,aesthetic.and recreation resources and socioeconomic acti-
vities.A discussion of the potental impacts is presented below for
each aspect.
4.4.1 Aquatic Ecosystem ImplicatIons
The magnitude of the expected effects of load following on the aqua.tic
ecosystem is dependent on several hydraulic characteristics and the
life stages of the aquatic species present in the river.The hydraulic
characteristics which will determine the magni,tude of effects inc.lude:
1.The magnitude of change during the 24-hour period;
2..The base flow from which increase to the maximum flow is
made;
3.Rate of change of discharge (up and dow~);
4.River channel morphology;and
A-51
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4.Dewatering and free2'~T.lg of incubating eggs;
A-52
6.Changes in ice processes which indirectly affect aquatic
resources;and
5.Attenuation of the change in discharge dOWI1.stream from the
dams.
2.Short-term.rapid changes in availabilj.ty and distribution of
various habitat types;
3.Delay or inhibition of upstream movement of adult salmon;
5.Inund.ation of incubating eggs with cold water in otherwise
somewhat protected areas (e.g.,overtopping of upstream be-
cause of side sloughs);
7.Potential increases in bank erosion due to bank instability.
1.Stranding or isolati,on of fish,primarily juveniles,when the
water surface elevation recedes;
TIle potential effects to the fisheries and aquatic resources due to the
load following operation include:
The following discussion outlines the types of effects which have been
experienced at other hydroelectric facilities as well as some aspects
which are associated with specific features of the Susitna River.It
alsoassUIlllas tMt the load following operation will occur at both Wa-
tana and De~il CanYon facilities.
Stranding of fish could be significant in areas where fish remain in
pools isolated from the main current as waters recede.These fish also
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become more susceptible to predation and dessication when the habitat
dewaters dt:e to water se!epage out of the pool through the gravels.
Juvenile salmon are particularly susceptible because they frequently
utilize shallow,near-shore access for rearing (ADF&G).
In addition to the potential for fish stranding,habitats utilized by
juvenile salmon for rearing may be seriously disrupted by cons tantly
changing mainstem discharges.Studies to date (ADF&G,1983)indicate
that at least in some areas,the ava.ilability of rearing habitats util-
ized by juvenile salmon is correlated with dischargeo With constantly
changing discharges in the river,juvenile salmon may not be able to
maintain themselves in an appropriate area because of the daily disap-
pearance of habitat or significant changes in water velocity_In other
areas ,juvenile rearing habitat ap.pears to be unaffected by mainstem
discharge and,therefore,may not be significantly affected by constant
changes in water surface elevation.This too,however,is highly de-
pendent upon the daily range of discharge fluctuation and water surface
elevation.
Daily load followiJ.1.g changes in discharges may inhibit upstream migra-
tion ofadul t salmon to the various spawning habitats..Data collected
by ADF&G over the past three years (ADF&G 1982,.ADF&G 1983,and pel'S"
comm.)show that during periods of rapidly rising discharges due.to
storm events,upstream movement of adult salmon nearly ceases.As the
flood peaks and discharge declines movement of salmon resumes"Daily
fluctuation in discharge could significantly delay m.ovement of a.dult
salmon to the spawning areas.
Beyond the potential delay in upstream.migrat.ion of adult salmon,daily
discharge variation could eliminate mainstem areas as via.ble spawning
and incubation areas for salmon due to the constant dewatering a.nd po-
tential freezing of sui table sites.Associated With this,sui table
spawning areas in sidesloughs and side channels may be rendered unsuit-
A-53
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able if there is daily ov-ertopping of the upstream berms with 'Lllainstem
water.
The above concerns are most commonly associated wi th river reaches im-
mediately bellow hydroelectric projects and are generally attenuated
further downstream.Upstream of the confluence of the Chulitna and
Talketna Rivers,little attenuation of the daily ~luctuation is
anticipated in the Susitna River because of the steep gradient in the
upstream reach.Downstream of the confluence area,some attenuation is
expected because of the lower gradient and the effect of inflow from
the major tributaries.'!be attenuation will be great,~st during the
open water season when flows are highest from the tributaries.
However,when tributary flow is low as in the winter mo1t"Lhs,daily
fluctuation j.n the Susitna River downstream of the Chuli.tna and Tal-
keetna Rivers will be more significant.
Potential effects of load following during the ice covered period could
possibly be more significant than during the open water season,al-
thoug~less directly observa~le.Under load following conditions,the
ice processes become somewhat more complex than without the project or
under base load operation of the project.In open water areas,daily
changes in discharge during the winter may result in considerable build
up of ice along the banks of the river.This would occur as a result
of exposure of the river bank during water level changes.The implica-
tion to the fishery .involves strand.ing of juven.ile fish and freezing of
incubating eggs in the spawning areas.
At the leading edge of the ice cover area,d3;ily flow variation could
cause pet'iodic flooding of floodplain areas and could result in.signi-
ficant ice jams.Increased flooding is associated with the increased
water surface elevations which &'L"e observed during the development of
the ice cover tmder current conditions.Additionally~the mechanical
action of discharge variation may taJt the integrity of the ice cov~r e
If the integrity of the ice CO~Ter is compromised,mechanical breaku.p
A-54
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Daily flow fluctuations may create a more irregular and broken ice sur-
£ac.e,therebY making river cX'ossingsby moose more difficult and ha--
zardous..As a resu!t,moose movements and habitat uSe along the ice-
4.4.2 Botanical and Wildlife Resource Implications
Minimization or avoidance of all potential effects may be achieved
through lim!tation of the range of daily flow changes and the rates of
change,both on the ascending portion and receding po.rtion of the hy-
drograph..The best method of defining acceptable discha.rge ranges
would be to define the maximtlln acceptable range of water surface eleva-
tion.change.
The downstream effects of daily flow fluctuations may include impacts
on moose movements,decreased beaver overwinter survival and riparian
habitat cha.nges..These effects would mainly occur in the ice-covered
portions of the river downstream to the vicinity of Talkeet'na..Below
the Talkeetna area flow attenuation and dilution by major tributa.ries
would likely reduce the effects to insignifj,cant levels..It should be
emphasized that until further hydrologic and hydraulic evaluations are
completed,effects o.f daily flow fluctuations on botanical and wildlife
re~ources are primarily speculatfve9
would occur as the ice cover rides the changing water elevation as
observed in the Peace R.iver in Canada.In addition,downstream.move-
mentof the ice to form.ice jams $imilar to what occurs during breakup
under existing cond!tions which in turn,could cause excessive flood-
ing.
The increased flooding could affect over-wintering habitats for juve-
nile salmon and resident fish through scouring of bed ma.terial,in-
creased 'velocities in suitable habitats,and.decreased temperatures
resulting from cold mainstem water inundation of warmer groundwater.
l
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A-56
Daily flow fluctuations may also reduce over-winter survival of beavers
due to the.entrapment of greater portions of food caches in ice andl
or the uprooting and washing downs tream of food caches.This latter
mechanism may also negatively affect beavers upstream of the ice-
covered portions of the r"{ver,.but the lack of ice cover may overshadow
the negative effect in this area.
covered portion of the river would be mo.re restric ted,and the paten-
t.ial for accidents and exposure to wolf preda.tion would be inc.reased.
The extent of ice damage to riparian vegetation may be increased due
to the greater ice movement and thickness result.ing from daily flow
fluctuations.Damage to vegetation due to higher summ,er flow fluctua--
tions may also occur.As a result,the UIlvegeta.ted floodplain may be
widened and the stage of plant succession may be retarded along the
many shoreline areas,at least initially_A wider unvegetated flood-
plain is likely to result in the long term as well.It is not clear,
however,wi thoutfurther evaluation,whether the long-term net result
would be to increase or decrease the availability of early successional
vegetation.The resultant long-term effects of these riparian bab!tat
changes on moose and.other wildlife are also unclear.
I
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111
I
3.3
2.8
2.7
2~6
2.6
Peak WorkForce
aequirements(xl0 3 )
103
83
70
57
49
Total Worker-Months
to First Power(xl03 )
CONSTRUCTION WORK FORCE REQUIREMENTS.FOR
ALTERNATIVE WATANA DEVELOPMENTS
Alternative
2185 FERC
2185 Modified
2100
2000
1900
A....57
5.0 REGIONAL SOCIOECONOMIC IMPACTS OF WATANA ALTERNATIVES
Differential impacts of the alternative Watana Developntents will pri....
marily result from differences in associated labor requirements.As
shown in Table A-I0 and Exhibit A-S J the modified Watana 2185 project
reduces the peak work force by 500 workers (15 percent)compared to the
peak.work force identified in the License Application.The l<.')wer dam
height alternatives will not significantlY further reduc~the peak work
force.Instead the schedule will be shortened.
Table A-I0
The modified Watana 2185 Development also reduces the total labor re-
quirem.ents by 20 percent.'lbethree.lower dam height and reservoir
alternatives further reduce these requirements by 16.31,and 41 per-
cent compared to the modified development design.
:It is anticipated that project-rela.ted population,employment and in-
come,housing,.services and facilities,and fiscal impacts will be si-
milar to those desc.ribed in Exhibit E co Differential effects related
to the Watana a1 ternatives will result from reduced peak labor require-
ments and a shorter construction schedule for the lower development,
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with resultant shorter duration of pea~requiren.;ents for housing and
other facilities and services.
The implications of load following on cultural,socioeconomic,recrea-
tion,aesthetic,and land use reSources cannot be accuratl!ly determined
until additional hydrologic and hyraulic studies are conducted and lm.-
til the results of those stlldies are factored into an analysis of load
following impacts on aquatic and terrestrial resources.
In general,based on available informat:ion,it is anticipated that load
following may decrease bank stability,thereby increasing 'bank erosion.
If this occurs,additional archeological and I or historic sites could be
eliminated..In addition,increased erosion and fluctuations of the
river level could potentially reduce the aesthetic quality of affected
areas.Furthermore,individual.sand businesses relying on fish and
wildlife resources for food,recreation,cultural,andlor commercial
activities (including hunters,trappers,guides,and lodge owners)
co".ld be negatively-affected if load following reduces the magnitude
of available.fish and wildlife resources in the projectiarea and if
load following makes navigation of the river (by boat during ice-free
months and by snowmobile during the winter)more difficult or hazar-
dous.Moreo',er,if load following increc\ses the likelihood of ice
jrnns and flooding downstream,the chances \of economic losses due to
flooding would increase.
A-58
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EXHIBITS
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54
••.~~;l><-...:~,"....._;.~";"':;;"""<·<:_''''''_''';;,'i.1''''4c-"''t';f.\l;)o''~i~~';:4\~,~.>ot~~_....._.~'''n::....-.-'';i'-'I~~~~~'
~~~~~.~..~.~~;
1900
2185
2100
2000
28.300
38.000
19.800
14.500
(iJ
AREA I'N ACRES:
RESERVOIHELEVATION:
",,"""~_'-f"""~-""""'--,......--~~~~~
WATANA
DAM
ALASKA POWEBAUTHORITY
SUSITNAHYDROELEOTRIC PROJECT UPDATE m
WA.TANA RESERVOIR AREAS ~
UNDER ALTERNATIVE DEVELOPMENT CONCEPTS ~
SEPTE~vlBER 1983 t
.,,_._----_.-~....."._~....,,-----------~.....-~.----_.-.....
'"
~·r...:3......... .:...'".....
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'~"li"'::P,1-"""";··':;;~'1;~~;.4,~~,A"'_'~~"i~p:3!"ti~~...~~""=~~;~~"~:._~~""+
~yt!:~.~~~._:..,;.""
\}
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EXHn~IT A-2
AVERAGE MONTJILYFLm~S AT GOLD CREEK
(Natural and Post-Project Conditions)
t"!@~"\
o
r~~"'-'in •.--~~~)111"---15\~
,
Scenario Oct.Nov.Dec ..Jan.Feb.March April May June July Aug.Sept.
Natural Flows 5,822 2,608 1,825 1,499 1,264 1,126 1,374 13,244 27,763 24,435 22,017 l3~45J,
Year 2000 t~atana only
4709 GWh Demand
l-latana 1900 7,808 6,870 7,802 5,192 4,218 4,168 4,152 9,543 16,190 14,904 22!017 13,661
Watana 2000 8,168 8,138 8,697 6,718 5,936 5,373 5,380 11,205 15,49 /+13,323 15,900 12,434
Hatana 2100 9,127 10,372 10,689 8,531 7,832 6,683 6,255 10,190 12,184 9,710 13,755 11,628_L.·i"~Watana 2185 8,822 11,138 11,146 9,636 9,012 7,782 7,608 9,460 10,147 9,258 12,680 10,443
-I 11
Year 2010,2-Development
",,4;;<'5945 G1h Demand
Watana 1900 +DC 8,644 7,527 7,058 6,184 fl.,Og8 5,500 6,620 7,743 10,507 16,094 21,057 13,558
Watana 2000 +DC 8,187 9,033 9,264 8,092 7,243 6,337 6,276 8,880 9,665 11,245 19,031)13,548
U'atana 2100 +DC 7,878 8,862 9,796 9,266 9,287 9,219 7,755 8,594 9,236 9,124 16,050 12,938
Hatana 2185 +DC 7,430 8,596 9,430 8,719 8,672 7,732 6,994 8,313 8,997 10,427 18,436 13,166
Year 2020,2~Development
7505 G\-111 Demand
Hatana 1900 +DC 8,716 7 f 297 7,054 6,121 5,924 5,429 6,211 8,528 12,123 15,369 20,363 13,558
Watana 2000 +DC 8,554 8,943 8,906 7,969 7,246 6,344 6,305 9,746 10,989 11,123 17,424 13,282 l:I.1
Watana 2100 +DC 8,957 10,197 11,274 10,001 8,908 7,049 7,5Q9 9,117 10,170 8,R87 13,548 11,449 ~
III
HWatana2185+DC 8,101 9,801 10,979 10,190 10,218 9,083 8,646 9,132 9,678 8,480 12,678 10,357 tp
H
J-3
Na tural Flows 5,822 2,608 1,825 1,499 1,264 1,126 1,374 13,244 27,763 24,435 22,017 13,45il ~
I
tv
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Au~ust December
Frequency (n=33)Frequency (0=33)
Natural 2185 2100 2000 1900 Natural 2185 2100 2000 1900
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8
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18
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10
9
14
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13
14
2
4
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4
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ExhibIt A-3
14
9
5
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.~:"',~
26 16
4 11
13 2 4
14 1 I
2 1
4
FREQUENCY DISTRIBUTION OF AUGUST AND DECEMBER FLOWS AT GOSD CREEK
\~atana Only
Year 2000,Demand I~evel=4709 GWh
.~-~."~~--"""""'-'
Average
Monthly
Flow (cfs)
866 -1,499
1,500 -1,999
2,000-3,264
3,265 -6,132
6,133 ....7,999
8,000 --9,999
10,000 ....11,999
12,000
12,001 --14,999
15,000 ....19,999
20,000 -24,999
25,000 -29,999
30,000 -38,533
~~
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.,,;....-$§b
December
Freque.ncy (n=33)
Natural 2185 2100 2000 1900
~':.~~e!~'':~
Exhibit A-4
.~.J
'f?~i
1 5 32
33 6 21 1
26 7
14 7 2
6 3 2
6 11 10
5 7 13
1 3 2
1 2 42
9
2
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14
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4
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August
Frequency (n=33)
Natural 2185 2100 2000 1900
FP£QOENCY DISTRIBUTION OF AUGUST AND DECEMBER FLOWS AT GOLD CREEK
Watana and Devil Canyon
Year 2000,Demand Level=5945GWh
~,-.;:~
866 -1,499
1,500 ....1,999
2,000 -3,264
3,265 ....6,132
6,133 -7,999
8,000 9,999
10,000 11,999
12,000
12,001 14,999
15,000 19,999
20,000 24,999
25,000 29,999
30,000 -38,538
Average
l1onth1y
Flow refs)
-.,....,."..,..,.~
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tzj
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December
Frequency (n=33)
Natural 2185 2100 2000 1900
~~""-,,,."-'"'-~'
5 5 7 32
3 J 23 1
18 10 3
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3 7 15
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4 3
13 1 2
14 1 2
2.1
4
August
Frequency (n=33)
Natural 2185 2100 2000 1900
FREQUENCY DISTRIBUTION OF AUGUST AND DECEMBER FLOWS AT GOLD CREEK
I'1atana and Devil Canyon
Year 2000,Demand Level=7505G1.J'h
i~-~~e ...,...~
Average
Uonthly
Flow (cfs)
866 -1,499
1,500-1,999
2,,000 -3,261
3,265 -6,132
6,133 -7,999
8,000 -9,999
10,000 --11,999
12,000
12,001 -14,999
15,000 -19,999
20.,000 --24,999
25,000 -29,999
30,000 --38,538
~~~"~."!,;JP,:,,!,I,
II
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t.Average ~cember Flows at Q>ldCree~
Highest 3,264 8,360 9~788 12,ltiB 14,714 8,491 11,514 10,513 9,839 8,491 10,677 13,237 12,328 3,264
25%excea:lan.ce 2,290 7,913 8,813 11,046 12,060 7,517 9,922.10,198 9,520 7,517 9,554 12,848 11,972 2,290
50%exceedance 1,700 7,780 8,623 10,576 iO,997 6,927 8,925 10,110 9,433 6,927 8,925 11,757 11,865 1700,
75%exceooance 1,465 7,6~8,519 10,331 10~J44 6,692 is,623 1O,Oqa 9,,364 6,692 8,925 11,O:n 11,179 1,405
Wl.iIeSt 866 7,538 8,349 9,944 9,387 6,261 7,356 7,900 9,070 6158 7.,19'9 7,675 7,624 866,
~
Average 1,825 7,802 8,697 10,689 11,146 7,058 9,264 9,796 9,430 7.,054 8,906 11,274 10,979 1,825
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k·...,···~_·,.··.·.··.~II.,J
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5,411
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~...........~..
5,934
".,.~,,~~~~-"·...·"""'--'.......,.;;.;;;.,..·~~c "..",.........i.,.~._.~..."".•,,'<"",;;.,-l...............~"....;."-"....,..........',_.....~"'"_>,,-""'._..,,'_._.~~<
.~~~~':J
5 "7C)(),/:,
!::1?::l~~j
4,280 5,032
~,-,:,~,-.J
3,762
Average August Flows at Cold Creek
(33 years of reconl)
EXlIDlrr I!r6
MIGlJsr AID DECEMBER FI..G1 DURATIONS
~~:;.....o;..;:o:,;:it.
2,9792,453
~i~~~~-;:;.;,:;:~"",,~:::::::;:-}-__:f
1,923
.",;:"'_;t
t-~.::ot,·,;:;.·.;;~
Year2lXX:>Year 2010 Yt?.ar 2020Nltural4700(;t.Jh llimarrl 5945 Qfu Iemarrl 7505 a.Jh Il:l......rl l'atura1FlowsHatanaOnlyHatanaan:]Devil Canyon Hatamarrl Devil Canyon Flows19002000210021851900200021002lB51900200021002185
38,53838,538 33,676 26,576 20,705 38,538 37,919 33.,944 38,538 38,538 36,197 25,9%>20,238 38~538
23,670 23,670 18,561 14,641 12,000 23,670 23,550 19,290 22,280 23,550 21,132 12,387 12,000 23,670
20,610 20,61D 14,367 12 s 059 12,000 20,540 19,144 13,505 17 ,396 20,l~60 15,943 12,000 12,000 20,610
19,290 19,290 12,517 12,000 12,000 17,170 12,127 12,000 12,000 i.J 624 12,000 12,000 12,000 19,Z:>Q,
15,2'74 15,274 12,(0)12,000 12,0(X}12,000 12,000 12,000 12,<XX}12,000 12,000 12,000 12,000 15,274
22,017 22,107 15,9)0 13,755 12,680 21,057 19,030 16,050 18,430 20,323 17,424 13,548 '2,678 22,017
~
~\);'~'it".;..~-::.;
Ie""J±:4'.c-itt
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Highest
25%exceedance
50%exceedance
75%exceedance
~st
Percent of Tine
Flows Exceeded
Average
Total Annual Average
ttt::~If~~ii
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,I
~,"ii!!iiJ!'E:t!,!'Jiel
WATANA AND
DEVIL CANYON
YEAR 2020
7505 GWh
ENERGY
DEMAND
25%
3%
5
NATURAL'~900 2000 2 ~00 .2 1 a5
PROJECT ELEVA nON
30
35
40
15
25
15
20
10
NATURAL1900 2000 2100 2105
PROJECT ELEVATION
25 25%
~~~-
WATANA AND DEVIL CANYON
YEAR 2010 5945 GWh
30 ENGERY DEMANO
20
15
15
\
WATANA ONLY 40
YEAR 2000
4709 GWh
ENERGY DEMAN D
35
25%
AUGUST
DECEMBER
1..•.
~ATURALlg00 2000 2100 218$
PROJECT ELEVATION
15
~
w
UJex:
()25
C
..Joo
a ---,.!
NATURAL 1900 2000 210Q 2185 NATURAL 1900 2000 210021$5 NATURAL :900 2000 2100 2185
I:-,'_0'\"
-.
EXHIBIT A-7
AUGUST AND DECEMBER FLOW DURATION CURVES
NATURAL AND WITH PROJECT OONDITIONS
3
PRO,JEOT ELEVATION PROJEOT ELEVATION PROJEoT ELEVATION
40
1-
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21"85 21"85 21'00 2000 19:00
FERC MODIFIED
ALTERNATIVE DEVELOPMENT
b~""(':I>.;:~;'"~~._~~J L~~-,!.'!''IN,.''.''.']..L:-:........'"'~~y':L.::.......Jt·PL1;L.~____.J~L ..._..J
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PROJECT LABOR REQUIREMENTS
[:.:"Jt".:.-::~·c;
2185 2185 2100 20001900
FERC MODIFIED
ALTERNATIVE DEVELOPMENTS
110 -...---------------------~I I
t=..•'."'"~H,.....cc'··r.~'L_~._~
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-
ENVIRONMENTAL IMPLICATIONS
OF
SUSITNA PROJECT ALTERNATIVEs
SEPTEMBER 1983
PAnT B
A COMPARISON OF ENVIRONMENTAL IMPACTS
ASSOCIATED WITH
ELECTRIC GENERf.TING ,PROJECTS ALTERNATIVE TO
SUSITNA HYDROELECTRIC DEVELOPMENT
•
I I
B-1
B-1
B--2
B-3
B-4
B-6
B-6
B--I0
B-13
Page
B-13
B-17
B--45
B-45
B-45
B-56
.B-71
B-78
B-79
B-BO
B-B3
o •
• •
••
• •
...
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TABLE OF CONTENTS
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• • • ••8 • • •Q ~• • • • ••s • • •
•••e • • •0 • • • • • • • • • • • • •
COAL • • ••• •..•• •II • • • •..• • • •II ..
NATURAL GAS •....• • •.. ..•e ..• • •It • • •..
CHAl<ACHAMNA PROJECT • • • • • • • • • • • • • • •
ENVIRONMENTAL ASSESSMENT • • • • • • • • • •..,
AIR RESOURCES • • • • • • • • • •
WATERRESURCES • • • • • • • • •
AQUATIC ECOLOGY • • • • • • • • •
TERRESTRIAL ECOLOGY •G •..• • •
SOCIOECONOMIC FACTORS • • • • • •
AESTHETIC FACTORS ..• • • • • • •
INTRODUCTION.
1.1
1 •.2
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2.1 BELUGA
2.2 NENANA
HYDROELECTRI CFACILITY -CHAKA,CHAMNA
4.1
4.2
4.3
4.4
4.5
4.6
REFERENC~S • •~• • • •
leO
2.0 COAL FIRED FACILITIES
3.0 NATURAL GAS FIRED FACILITIES
3.1 COOK INLET GAS
3.2 NORTH SLOPE GAS
5.0 SUMMARY AND CONCLUSIONS
6.0
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LIST OF TABLES
B"'l NATURAL AND ALTE:RNATlVE E REGULATED MEAN MONTHLY
AND MEAN ANNUAL FLOW A'1'THE CHAKACHAMNA LAKE
OUTLET B-S2
B-2 ESTIMAT£D ESCAPE!~NT OF IMPORTANT FISH SPECIES
IN THE CHACHATNA.RIVER SYSTEM BY WATER BODY
CLASSIFIED BY POTENTIAL EFFECTS OF DECREASED
FLOW OF WATERFROlrf CHAkACHAMNA LAKE B-66
B-3 ESTIMATED ESCAPE11ENT OF IMPORTANT FISH SPECIES
IN TIlE MCARTHUR RIVER SYSTEM BY WATn BODY
CLASSIFIED BY POTENTIAL OF INCREASED FLOW OF
WATER B-69
B-4 ENVIRONMENT RELaTED FACILITY CHARACTERISTICS
FOR ALTERNATIVE POWER GENE&\TION OPTIONS B-Bl
B-S QUALITATIVE RANKING OF ENVIRO~reNTAL IMPACTS
ASSOCIATED WITH ALTERNATIVE PROJECTS B-82
Table No.Title Page
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1.0 INTRODUCTION
PARTB
A COMPARISON OF ENVIRONMENTAL IMPACTS ASSOCIATED WITH
ELECTRIC GENERATING PROJECTS ALTERNATIVE TO
SUSITNAHYDROELECTRIC DEVELOPMENT
1.1 COAL
This study presents a comparison of first-order.environmental
impacts associated with the development of selected proposed
electric power generation projects that are alternatives to the
SU$itna Hydroelectric.Pro ject..These alternatives are ba.sed on two
other fuel types in addition.to hydroelectric power,coal and
natura.l gas,and four technologies:coal fired steam electric
generation,gas fired simple cycle (combustion turbine),gas fired
combined cycle (combustion turbine with staam heat recovery
boilera),and hydroelectric.
There appears to be two vi.able locations for development of a coal
facility alternative,the.Beluga region or Nenana region (Ebasco
1981 a,b)..The Nenana location can probably support up to
approximately a 4QO MW facility,while the Beluga potential is much
greater e CUI'rent :load forecasts indicate that the Nenana facility
The coal and gas alternatives,in terms of development and location.)
are somewhat complex.A bri.ef condensation of the current trend in
development options for these alternatives is given below,as well
as a summary description of the rihakachamna project,the
hydroelectric a.lternative.
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Development of natural gas 1'1ould first utilize Cook Inlet reserves
(AlaSka Power ~thority 1983a).Power plants would be located in
the Bel~ga region and/or the Kenai/Nikiski !..cea.Pevelopment in the
Beluga .region will require erect.ion of a new transmission line as in
the coal utilization scenario,while plant development in the
Kenai/Nikiski area will require transmission line construction from
the plant location to Anchorage (Alask!Power Authori.ty 1983a,b).
Current load forecasts and projected gas field reserve data indicate
that at some future date utilization of North Slope gas would be
required,upon depletion of Cook Inlet reServes (Alaska Power
Authority 1983a)e There are three feasible locations fora power
plant utilizing North Slope gas:the North Slope,Fairbanks,and
would event~ally be inadequate to meet demands (Alaska Power
Authori ty 1983)•The suggested development option is the
simultaneous development nf both Nenana and Beluga fields:·(Alaska
Power Authority 1983a).
1.2 NATURAL GAS
The devalopment of the Beluga field will require,in addition to'
power plant construction,the erection of a major new transmission'
line from Beluga to the Willow Substation along the Intertie.For
purposes of this study,to parallel assumptions made in the economic
\evaluations,it is assumed that a mine and mine support facilities
have preViously been developed (Alaska Power Authority 1983a).
Potential significant environmental impacts from mine development
are therefore not presented in this document.Similarly,the
construction of a power plant at Nenana will require an upgrade of
transmission line facilities and mine expansion (Alaska Power
Authori ty 1983a)"Impacts from the pr0!)osed mine expansion are not
evaluated in this documente
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McArthur Tunnel Alternat.ives A and B -diversion of flow from
Chakachamna Lake to McArthur Valley to develop a head of
approximately 900 feet via a power tunnel (lake tap).
Alternative A would divert all stored water,while Alternative B
'Would maintain approX:i.mately 19 percent of the average inflow
into the lake for release to the ChakachatIlB River,
Kenai/Nikiski (Alaska Po'Wer Authority 1983b).The North Slope
location would utilize untreated natural gas in simple cycle
combustion turbines..A major new transmission line from the North
Slope to FairbCilnks via the Utility Corridor and an upgrade of the
Fairbanks-Anchorage interconnection would be.required.A power
plant situated a.t Fairbanks could be supported via a new small
diameter gas pipeline from the North Slope,or a tap from the
proposed .Alaska.Natural Gas Transportation System (ANGTS)line,or
a.lternatelya tap from the proposed Trans Alaska Gas System (TAGS)
pipeline..An upgrade of the Fairbanks t.O Anchorage transmission
system is required.A power plant at the Kenai/Nikiski location
would require development of the TAGS system.A major transmission
line from near tidewater to Anchorage would also be required (Alaska
Power Authority 1983b).
Chakachatna Dam -con~truction of a dam in the Chakachatna River
canyon approximately 6 miles downstream from the lake outlet.
1.3 CHAKACHAMNA PROJECT
The Chakachamna Project is a proposed hydroelectric development of
approximately 300 to 400 MW in capacity in the vicinity ofLaks
Chakachamna and the Chakachatna and McArthur rivers..There are
currently six alternate development scenarios for this project which
are signi.ficantly different in design and scope.These alternatives
are as follows:
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Chakachatna Tunuel Alternatives C and D -similar to A and B
above,a lake tap would be developed.This tap would be through
the right wall of Chakachatna valley and the powerhouse would be
downstream in the valley.Alternative C would divert all flow,
while Alternativ~D would maintain a release of approximately 30
cfs at the natural lake outlet.
Alternative E -essentially a refinement of Alternative B ..
Specific facilities are provided for maintaining instream flows
and fish pa.ssage..Reservoir drawdown is also restricted ..In
addition,a tunnel boring II1achine rather than "drill and shoot"
techniques (utilized in Alternatives A-D)is employed ..
409l.A
1 ..4 ENVIRONMENTAL AS SESSMENT
First-order environmental impacts may be defined as impacts directly
related to various power plant and auxiliary facili ty
characteristics and represent the primary effect.s of the development
on the environment..Impact evaluation has been performed by
technology (coal,gas,or hydroelectric)within diSCrete
environmental categorie s.These categories include air resource s,
The Chakachatna Dam has been dropped from serious consideration for
foundation considerations,as well as fishery impact
considerations.Alternatives A and C lilould result in a loss of the
anadro1J1ous fishet'Y (including approximately 41,000 sockeye salmon)
a.nd are therefore also not under serious consideration at this
time..Of the remaining alternatives,Alterns.tive EiB the preferred
alternative and appea.rs to be the configuration to which the project
would be developed,should the Chakachamna Project be constructed
(Bechtel 1983).r
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water resources,aqua.tice:cology,terrestrial ecology,aesthetics
and socioeconomics.Each environmental discussion outlines the
option 3.fid location sp$cific f'actors for each of the alternatives
described above.
A brief summary and conclusions sectioI'follows the detailed
alternative discussions.A table is presented which shows a
qualitative comparison of impacts within environmental categories
for the various development options.
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Construction activities may cause temporal localized impacts due to
dusting.These impacts are not expected to be great or 'persistent.
The long term impacts from operation of transmj.ssion lines are
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The two viable locations for the coal fired power plants.are in the
Beluga coal field region and Nenana coal field region.Environg
•
mental impacts associt ad with the development of these facilities
is discussed below.
2.1 BELUGA
2.0 COAL PlRED FACILITIES
2.1.1 Air Resources
The emissions of products of combustion [particulates,sulfur
dioxide (S02)'and nitrogen oxides (NOx )]form the prime
potent.ial for impacts to the air resources at this location.
Anticipated emissions are 0.03 Ib particulate matter,0.6 lb S02
and 0.6 lb NO perm:lliion Btu,utilizing a typj,calparticulatex
emission control device s\Jch as an electrostatic precipitator or a
baghouse,and a flue gas desulfurization system to control S02
emissions.Compliance wi th regula.tory criteria.employing Be st
Available Control Technology should minimize adverse impacts.The
location of the Class I area at Denali National :Park could pose the
most severe siting constraints for a development of a coal fired
facility at this location.The allowable increments of air quality
deterioration are extremely small in Class I areas.A minimum
distance from this area.would probably be at least 20 miles,but
each potential site should be analyzed in great detail to ensure a
proper evaluation..The Class I visibility regulations could
Significantly affect this minimum distance.
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expected to be negligible.The transmission lines would generate
smallamouIlt of ozone which would be undetectable at ground levels
and would not cause problems with nearby vegetation.
2el.2 Water Resources
A coal fired facility generally has significant water requirements.
Requirements for a generic.200 MW facili.ty have been estimated at
approximately 300 gpm for a plant employing dry cooling,or 1,950
gpm for a facility utilizing wet cooling towers.Thr.ee potential
water supplies at this location include the Beluga River,Cook Inlet
(sea~ater)J and groundwater.
Flow data for the F,eluga River is not immediately a·~ailable.
However,from a rea""rai nfall considerations,it appears tha.t
streamflow reduction would exceed IOpercent,and that groundwater
supply would be the more viable alternative at this general
location.Althc~gh well yields have been estimated as high as
1,000 gpl"J near surface resources in the Beluga area,characteristic
yields appear to be only 10 to 100 gprn.Thus,water withdrawals
could.be a major impact at this loca.tion.
The facility would most probably be.designed to function in a z~.ro
discharge mode.Therefore"impacts to water quality through
discharges are expected to be minimal.
Construction activities of the transmission lines between Beluga and
Willow substation would result in temporary impacts.The
transmission lines would cross seVeral rivers Cind numerous creeks,
resulting in temporary stream siltation,bank erosion,and the
potentia.l.for accidental spillage of lubricating oils and othe.r
chemicals into the W'aterCf.)urses.Construction eqUipment along
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2.1.4 ~~estrial Ecology
Impacts to fisharies from transmission line Construction,such as
increased runoff and sed,imentation could occur through clearing of
the right-of-way and (~rossing of wate.rcourses by construction
equipment.The introduction of silt into streams can delay
hatching,reduce hatching Stl;CCess,prevent swimup,and produce
weaker fry.Siltation also reduces the benthic food organisms by
filling in available .illtergravel habitat.These potential adverse
impacts can be reduced or eliminated through contruction scheduling
and good engineering practice.
2.1 ..3 Aquatic Ecology
streambanksor crossing sma.ller streams c.oul.d cause direct siltation
of the watercourse or cause indirect streambank erosion and
siltati.on through the removal of vegetation a.nd disturbance of
pe1."D1afrost..The effects of siltation could alter stream channels,
fi.ll ponds,or damage aquatic flora or fauna.These potential
adverse impacts can be reduced or eliminated through appropriate
mitigation measures and good engineering practice.
Assuming a gl~oundwater supply is utilized,and the plant is designed
in a zero discharge mode,impacts from facility operation to aquatic
ecosyste~s are expected to be negligible~Significant,difficult to
mitigate impacts should not ocCUr.
40B5A
The greatest impact on the terrestrial biota.resulting from the
development of a coal fired power plant at Beluga will be the loss
or alteration of habitat and disturbance-related impacts.Potential
power plant locations contain seasonal ranges of Dloose~caribou,and
bears,as well as n~erous small game spec:i.es.Land requirements
would be on the order of 75 acres for a 200MW facility.This loss
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of habitat would have varying impacts depending on specific fac~,lity
siting,howeve.r,some impacts could be antici~)ated,most no\tably
loss of carrying capacity of the land to support the above.speHies.
Impacts would be more severe if the facility was located in an
undeveloped area requiring access ~oads.
Another tidldJ iieimpact results from birds colliding with the
cooling towers.Thesignif1canceof this impact is highly dependent
on cooli.ng tower design and location in relation to dail~and
seasonal migratory routes.Locations subject to frequent fogging
may also increaSe the significance of this impact •Bird collision
impacts,however,can be mitigated through proper siting.Major
migratory bird corridors occur throughout Cook Inlet and l'rince
William Sound.
Impacts from.construction of the transmission line are poteni:ially
significant.Right-of-way requirements would require a m~,nimum
clearing of a 110 foot strip in vegetated or forested nreas.
Disturbance or alteration of this habitat could haVe sigpi~!icant
impa.cts,particularly near trumpeter swan nestitlg sites,moose
calving areas,and bear denning sites.Detailed si.ting and r.)uting
studies are required to properly identify and minimize these
potential impact.s.l:hwever,some .moderate impac.ts can be
antici.pated.Impact.s due to bird collisdons may also be locally
important.
2.1.5 Socioeconomic Factors
Most of the communities located near the Beluga coal field&are
generally small inpopula.tion and have an infrastructure that ill not
highly developed.In light of this,the construction and operHtio.n.
of a power plant has a.high potential to i1l1pact local communities
and cause a boom/bust cycle.In the area,the largest commul1ity,
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2.2 NENANA
2.1.6 Aesthetic Factors
2 ..2.1 Air Resources
For a 200 MW facility,a peakconstruct:1cn workforce of 500
personnel and an operational workfo~ce of over lOOpersonnel is
estiDiated to be reql.1ired.Transmission line construction personnel
requirements would add significantly to these figures.Hence,major
socioeconomic fmpa(:ts.should be anticipated at this location.
::t'yonek.only has a population of 239.While a construction camp
could mitigate this impact to some de~ree,.disturbance of the area's
infrastructure.must be antlc:f,pated.
The visual impacts from the new transmission line are also
significant.Much of the area where the lines could potentially be
routed are pri stine wilde-:tness;large transmission towers and lines
are considered to be a fJigrdficant degradation of the ·viewscape.
The a1.r resources considerations for a coal fired facility in the
Vicini ty of Nenana are similar to those discussed above for the
Beluga location.!ioW'ever"Nenana is situated in a Class I PSD area
and in a nonattainment area for catbonm()noxide (CO)emissions.
This itnplies that a high degree of effort 'Will be required to
4085A
The relatively large land requirements,facility structures,storage
areas "and stack plumes have the potential to cause signif.icant
visual degrada,tion,from an aesthetic viewpoint.In addition,
moderate noise impacts can be expected from facility operation.
Odors should not be a significant difficulty,if good engineering
and operation practices are followed.
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Wa teL requirements and considerations would ba similar to those at
the Beluga location.Bowever,sufficient slJ,.rficial$upplies exist
ill the nearby river systems (e.g.,temana and Nena.na rivers)so tha.t
liater use would have negligible potential enVironmental impacts.
achieve satisfactory emissions levels at this location.From a
regulatory standpoint,receivlng an offSet and siting a coal fired
facility at this location could prove to be very difficult.
Therefore,impacts to air resources at this location must be
considered to be extremely significant.Extraordinary emissiolls
control measures would be required to satisfy regulatory criteria.
2.202 Water Resources
Construction considerations for a transmission line upgrade would
not be significant in comparison to the Beluga location..However,
Some minor,temporal impacts could be anticipated.Good
construction prdctices would serve to mitigate against any adverse
impacts.
2.2.3 Aquatic EcplogX
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The Nenana location is inproximi ty to ('~ne of the more access!ble,
urbanized areas of Alaska.Considering other developments in the
vicinity,coupled with llinimal liastewater discharges and la.rge
nearby river systems,the impacts to the aquatic ecosystem from the
development of a coal fired fae.:tlity at Nenana are anticipated to be
insignificant.Minor,temporal impacts could occur from activity
associated with the transmission line upgrade;however,no long term
impacts are anticipated.
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2.2.5 Socioeconomic Factors
2.2.4 Terrestrial Ecology
The impacts on the terrestr!",oJl.biota from development e>f a coal
fired facil!ty at Nenana are expected to be similar to those at
Beluga.IUtbitat losses wou.l:d be similar,and this location also has
seasonal ranges of moose,caribou,and bears..While thefac.ility's
te>tal land requirements are modest (approximately 75 acres fora 200
MW plant)"disturbance of range areas at this location will lower
the carrying capacity of the land to support these species.This
could represent a significant terrestrial impact.Impacts would be
more severe if the facili.ty was located in an undeveloped area
requiring access roads.Transmission line upgrading i.s not
anticipated to haVe any significant long term impacts to the
terrestrial ecology.
If the Nenana coal field site is located with an approximately 50
mile radius of Ff~-"'banks,a boom due to construction will be an
unlikely event)~ice many of the 500 construction personnel could
cotmDute to the site from Fairbanks.The impact of project
construction 'Would also be mitigated by the sizeable Fairbanks labor
market and high unemployment rate.A site located further than 50
miles from Fairbanks WOUld,however,incur impacts similar to those
anticipated at the Beluga field site.However,the magnitude would
not be as e:xtreme as the Beluga.location.
2.2.6 Aesthetic Factors
Aesthetic considerations would be identical to those discussed for
Beluga,with the exception that there would be no additional major
factors associated with transmission line construction.
4085,A
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3.0 ~lATURAL GAS FIRED FACILITIE:S
The developm.ent of a natural gas fired energy development scenario
will proceed with the utilization of Cook Inlet gas at Beluga or
Kenai,followed by the utilization of NOr'th Slope gas at either the
North Slope,F.l1irbanks,or Kenai.Environmental impacts of these
various options are presented below in the abo~e order.
3.1 COOK.INLET GAS
3.1.1 Belua~
3.1.1.1 Air Resources:The considerations for a combustion turbine
located at'Beluga are similar to those for a coal fired facility at
this location.The major difference is that :N0xrathe.r than S02
or particulates is the polluta.nt of concern,due to high combustion
temperatures and the low sulfur content of the fuel.An improperly
operated facility also has the potential to emi t high levels of
uncombusted hydrocarbons;this should not pose any problems if
correct operating procedures are followed.Steam plumes from NO x
water injection control could have minor local impacts.Con-
struction and transmission line considerations would be identical to
those tor a coal fired facility,essentially minor and t~mporal.
3.1.1.2 Water Resources:The water conSiderations are similar to
those for a coal fired facility at this location;groundwater would
still likely be the supply source.Water requirements would be
minor,however,approximately 200 gpm for the plant,excluding wClter
injection requirements for NO control.If this type of controlx
system.is included,an additional requirement of 500-800 gpm may
result in significant impacts to the water resources from water
withdrawClls,as in the cause of a coal fired facility ..Discha.rges
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fired facility at this location.
are negligible,and no significant1mpacts to the water quality are
a.nticipated.ConstI'uction antttransmission line impacts to the
watel:resources should be identical to those noted for the coal
}.1.l.3 Aquatic Ecology:The impacts to aquatic ecology parallel
those of a coal-fired facility at this locatione Significant,
difficult to mitigate impac.ts should not occur.
3.1.1.4 Terrestrial Ecology:The i':.cts to the terrest.rial
ecology would be almost identical to thc:::_for a coal fired facility
at this location..The key impacts are associated with habitat loss
and disturbance.Transmission line considerations would be
identical.
3.1.1.5 Socioeconomic Factors:The socioeconomic considerations
would be very similar to those for a coal fired facility at this
location.The peak construction workforce would be around 200
personnel and an operational workforce of 130-150 would be
required.A boom/bust cycle could be anticipated,together with
long term communit)"alterations,resulting in major socioeconomic
impacts to surrounding small communities.
3.1.1.6 Aesthetic Factors:Aesthetic considerations would be very-_...;;;;..--....;;.;~-.;...-.;...~-.;...~.....-.;;..
similar to those for a coal fired facility at this location.Plant
facilities and the assovtated transmission line would create
noticeable degradation of the viewscape;plant noise ~ould also
cause a localized impact.
3.1.2.1 A;ir ""Resources:The impacts to air resources should be
similar to those for a combustion turbine located at Beluga.
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3.1.2.4 Terrestrial Ecology:The impacts to the terrestrial
ecology would be similar to those for the facility located at
associated ~ithimpactsshouldmitigatepotentialadverse
transmission.line constructiono
However,there d~not appear to be as significant regulatory
considerations,as the nearest restricted area occurs in the Tux:edni
National Wildlife Refuge,across the inlet to the south..NO
x
controls (water injection)would still likely be required;therefore
unmitigatible impacts to air resources are not anticipated.
.3.1.2.2 Water Resources:The water supply at this loeation will
likely come from groundwater supplies,lI1hich are ample.Water
requirements will be identical to those for the facility at Beluga
(approximately 200 gpm and SOD-800 gpm for NO control)•
x
Similarly,discharges are infrequent and impacts to water quality
are anticipated to be negligible.Impac.ts from construction of the
transmission line would be similar to those discussed for the Beluga
coal fired facility.Areas of concern revolved around siltation,
erosion,and streambed disturbance_Good construction practices
3.1.2.3 Aqua.tic Ecology:The impacts to the aquatic ecology Would
be similar to those associated "With a facility located at Beluga.
Essentially,groundwater Withdrawal and infrequent dincharge
preclude significant impacts to aquatic ecology.
Impacts assoc:iat 'Jd with transmission line construction would be
similar to those of the Beluga location,and identical to those for
the Kenai North Slope gas scenario,discussed below.To minimize
and mitigate these construction impacts,careful scheduling and good
engineering prac.tices are required..However,moderate impacts to
aquatic ecology can be expected.
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4086A
B-IS
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4086A
Transmission line impacts would be identical to those discussed
below for the North Slope gas scenario.Essentially,most of the
peakworkforc$of over 200 would be hired from the labor pools at
Kenai and Anchorage.
Beluga,with e~sentially habitat loss and disturbance being the key
issues.However,the more developed nature of the Kenai location
results in lower overall wildlife usage,as avoidance has already
occurred to a certain extent.
The impacts from construction of the transmission lines will be
similar to those of the Beluga location,and identical to those for
the North Slope {5~c;scenari.o discussed below.Moderate impacts due
to alteration and elimina.tion of vegetative cover and associated
chang$s in small game and non-game communities can be anticipated.
I'otentialfor bird collision impacts will a+80 .be created.These
ca~be minimized by ca.refulsiting and routing.
3.1.2.5 Socioeconomic Factors:Socioeconomic impacts at this
location are not expected to be nearly as severe as those at the
Beluga location.The relatively large population base in the area
will tend to mitigate any potential boom/bust cycle,although some
effect can be anticipated through increased employment
opportuniti$s.'!'he creation of 130'"'150permanent jobs may be
c.onsidered as a positive impact.However,demand for housing could
pOSsibly exceed the existing supply.
3.1 ..2.6 Aesthetic Factors:Aesthetic parameters w~llld be similar
to those for t:he .Beluga location.However,due to the previous
developments on the Kenai side of Cook Inlet,the actual impacts
would not be considered nearly as signficant as for those in a
pristine wilderness area.Again,both visual degradation and noise
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The cOlnstruction of facilities would result in tem.porary air quality
impacts.The use of hea.vy equipment and othe.r construction vehicles
,'\,
3 e 2 NORTH SLOPE GAS
4086A
As described in the introductory section,the North Slope gas
utilization scenarios consist of three iocation specific
alternatives:generation at the North Slope,Fairbanks,or
KenailNikiski..Environmental considerations for these locations are
presented below.
-
ou.tput would be the mostsignifican,t factors.Proper design and
landscaping should serve to minimize these impacts.
3.2.1 North Slope
B-17
3.2.181 Air Resources:As noted in the previous combustion turbine
discussion,the prime air resource consideration encompasses NO x
emissions,and the control of such emissions by water injection.
However,water or steam injection in the Prudhoe Bay area causes
undesirable levels of ice fog..Furthermore,water or steam
injection requires fresh water supplies that are generally not
economically available on the North Slope.For these reasons,air
quali ty regulatory agencies have not defined BACT for the North
Slope to include using water or stea.m injection to control nitrogen
oxides.Impositic.;n of the requirement for water or steam injection
would add substantial costs and significantly decrease the relative
feasibility of this option.Wi th no water injection requirement,
air quality regulations would not be likely to hamper installation
of a gas-fired pOwer plant in the Prudhoe Bay area.However,a
judieious siting effort would be necessary to avoid compounding any
air pollution problems from existing facilities.
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would generate fugitive dust as well as exhaust emissions.The
dusting problem is known to be especially severe during certain
periods of airinV'ersion conditions at this location.Tight
construction period schedules may not permit construction delays
during such inversion periods,creating a si~nificant yet temporal
impact.
3.2 ..1.2 Water Resources:The principal effects of the proposed
North Slope generating facility on the water reSOUrces of the
Prudhoe Bay area includeconsumptive withdrawals from freshwater
sources (existing lakes)for potable supplies and miscellaneous uses
such as equipment wash-down.Because the generating statio.n will
require mi.nor volumes (approximately 50 gpnr)of water and will be
served by existing water treatment facilities in.the area,water
resources effects associated with these uses will not be significant.
Transmission line construction between the North Slope and Fairbanks
may impact the quality of surface water resources through erosion
caused by larid disturbance,but has little Qr no impact on water
supplies.Erosion control,especially in ste.ep terra.in or areas of
susceptible sc\11s,will be a major requirement imposed by permits
issued for l~ight-of-way clea,ring and construction of the
transmission and related facilities,such as access roads.For
example,the Bureau of Land Management (BLM)land use plan for the
Prudhoe Bay-Fairbanks Utility Corridor (.BLM 1980)within which the
transmission facilities would be routed,specifically requires
protection of stream ba.nks and lake shores by restrict:i.ng activities
to prevent loss of riparian vegetation..Other water resource
transmission line cbnsiderC1tions would be similar to those presented
for other locations.
4086A
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There are a number of secondary environmental effects,related to
transmission line cons truction which should also be considered.
Between the North Slope and Fairbanku,the transmission line would
croes as many as 150 waterbodies which are utilized by fish for
migratiotl,rearing.spawning)and/or wintering.Siting should avoid
or minimize impact to spawning areas in approximately 35 waterbodies
and to Wintering areas in approximately 15 wat(;X'bodies.
B-19
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4086A
3.2.1.3 Aquatic Ecology:~'he majoraqua.tic ecosystems of the North
Slope area include the marine enVironment of the Beaufort Sea,the
freshwater environments of the Sag and Put Rivers and their
tributaries,and estuarine habitats at the rivers'mouths.Shallow
lakes in the area do not support fish because of complete freezing
in the wintertime.Deeper lakes may contain resident species such a
stickleback,but in general,knowledge of these lakes is presently
limited.In the rivers and estuaries,two groupsDf fish are
considered important:river fish such as the grayling,and
anadroTIlous fish such as the Arctic char and cisco.The anadromous
species descend local rivers at ice-breakup to feed in the shallow
littoral and sublittoral zone of the Beaufort Sea.They ascend
these rivers in the autumn alld overwinter in.deep pools.These fish
do not appear to undertake extensive migrations up the Sag or Put
Rivers.
These fishery resources could be affected by construction and
operation of a water supply intake,pipeline and access road
construction,gravel mining in rivers which could affect
overwintering and general habitat quality of the fish,and the need
to cross larger ):iver channels 'Which could interfere with fish
.passage.The latter item may require the use of .special culverts to
maintain migratory routes.Each of these potential effects would be
analyzed on a site-specific basis,and detailed impact aVoidance or
mitigation measures developed.
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B-20
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Construction of a power plant,sWitchyard,construction camp and
related access roads will disturb approximately 65 acres of land.
All construction equipment should be restricted to areas covered
with a gravel pad •Tundra adjacent to the generating fa.cili ty
should :not be disturbed.
Q)unterpoise (ground cable)c.onstruction may require excavation in
streambeds;this activity must be carefully planned (both spatially
and temporally)and monitored in ac.cordance wi th individual permi t
requi.rements.Conditions vary along the corridor,so that
environmental protection stipulations imposed by the regultory
agencies will tend to be site-specific.
3.2.1.4 Terrestrial Ecology:The North Slope area and specifically
the river delta areas provide a variety of habitats that are
important to a diversity .0£plants and animals.Project related
impacts which require special consideration include:(1)direct
habitat elimin&tion through the construction of project facilities,
access roads,and gravel bC5rrow areas;(2)indirect habitat
elimination resulting from access roads which impede drainage or
~hich generate significant traffiC related dust;and
(3)restrictions to large mammal movements,especially caribou.
Because the generating facility will be located within the Prudhoe
Bay industrial complex,terrestrial habitat impacts engendered by
this project will be an added increment to those which have already
occurred as a result of oil field development.Final siting efforts
should include evaluation of the factor$listed above,and will be
the mechanism through which highly significant terrestrialimpact$
can be avoided,particUlarly the indirect impacts and migratory
blockages.The direct impacts of habitat removal due -:0 facility
4086A
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construction are generally u.navoidable,but can beminimt~sd through
careful site planning and constructionman~,gement.
Imp;Jcts from transmission line development should also be
conl;lidered.CO'ilstruction of the transmission line facilities w.tll
require vegetative clearing in forested areas.Clearing should be
restri.cted to the folloWing categories of vegetati.on:trees and
brush whi.ch may fall into a struc.ture,g11Y,or conductor;trees and
brush into which a conductor may blow duril1g high winds;trees and
brush within 20 feet of a conductor or wi.thi.n 55 feet of the line
centerline;and trees or brush that may interfere with the assembly
and erection of a structure.Bird collisions with transmission line
conductors and other facilities are also on and at major river
crossings.
Between the North Slope and Fairbanks,much of the area south of
Nutirwik Creek wi.ll require cleari.ng of tr,~es wi thin the
right-of-ws.y.Because two lines will be bui.lt and trees wi thin 55
feet of the line will be cleared,the total wi.d th of cleared
vegetation will be 220 feet.Over the length of the line)
approximately 7,000 acres will be cleared.
The transmission line corridor passes through a wide variety of
terrestrial ecosystems,and is adjacent to several major federal
land areas which have been protected,in part,for their wi.ldlife
values.The Bureau of Land ~~nagement (BL~)land use plan for the
Utility Corridor (BLM 1980)has identified several areas as
containing Cl"itical wildlife habitat.Specific management
restrictions have not as yet been formulated;however,mea.iures may
be reqUired for a number of areas.
The land use plan also specifically requires protection of raptor
habitat and critical nesting areas.Protection of crucial raptor
4086A
B-2!
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4086A
3.2.1.5 Socioeconomic Factors;Potential sClc!oeconQmic and land
use effects of the North Slope scenario in.eludeboth temporary
impacts related to the influx of W'orkers and permanent land use
impact~,
habitats preserves the integrity of raptor population and maintains
predator-prey relationships.Facilit:1es and long-term habitat
alterat:1ons are prob1b:1ted W'ithin one mile of peregrine falcon nest
sites unless specifically authorized by the U.StlFish and Wildlife
Service,because of the endangered speciesstatuB of the peregrine
falcon.As the transmission line corridor generally avoids known
nesting areas,the restrictlotl may only apply to material sites.
System design must allow free passage for caribou,but t~ese animals
should not be a major consideraton in s1.ting ..·Carnivore/human
interaction .is a major concern in facilities design and in
construe/cion and operations methods,but not in siting
considerations.
Line routing and tower siting should avoid o:rminimize disturbance
of the treeline white spruce stand at the head of the Dietrich
Valley,which has been nominated for Ecology Reserv¢status.
Itfs unlfkely that the transmission line would be sited in or near
1mportantDall sheep habitat.A pr:1mary COllcern is aircraft traffic
over crt tical wintering,lambing,and movemlant areas.Moose winte.r
browse habitat in the Atigun and Sag River valleys is limited to
areas of tall riparian willow.Habitat has already been eliminated
by the construction of Trans Alaska Pipe:line System (TAPS)and
further destruction of this habitat should be avoided or minimized.
The willow stand along Oksrukuyik Creek,in particular,should not
be disturbed.
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Since the generating 'plant would be located within the Prudhoe
Bay/DeadhoI'se industrial complex,the in-migrating workforc.~'Would
not significantly affect the social and economic structure of the
re.gion"The workforce requirements are small in comparison to the
existing size of the transient workforce in the Prudhoe Bay region.
For f.ive months of each year during the period 199.3 throgh 2010 a
maximu1.'lJ.of 200 employees tiill be needed to assemble the
prefabricated units of the plant.Housing far-ilfties would be
provided for the employees at the adjacent construction camp.
Dllring off-'work periods,the majority of the employees would spend
time outside of the borough.The operations tiorkforce is expected
to be approximately 150 and will reside in the labor camp.The
spending of wages earned by the employees wi thin the North Slope
Borough is expected to be minimal due to the transience of the
workforce.
The use of la.nd for an electrical generating plant tiould be
compatible with the land uses of the industrialencl.",ve.The
Coastal Zone Management Program for the North Slope Borough has
delineated zones of preferred development.Permanent facilities are
allowed in the industrial development zone,consisting of the
existing Prudhoe Bay IDeadhorse complex and the Pipeline/:aaul Road
Utility corridor (North Slope Borough 1978).The generating plant
would be located within the preferred development zone.
Within the :Prudboe Bay/Deadhorse complex,the plant would be located
to minim:l.zeinterferences with e~isting or planned facilities,
including bUildings,pipelines,roads,and tra.nsmission lines.Land
ownership and lease agreements will limit the land a,\failable for the
electrical generating facility-
40~6A
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4086A
B-24
3.2.1.6 Aesthetic Factors;The potential aesthetic impacts of the
proposed North Slope devt,lopment.espeeial.1ythe tra.nsmission lines,
Permanent facilities would be consolidated at carefully selected
locations in the vicinity of Livellgood Camp,Yukon Crossing ,Five
Mile Camp,PIospect,Coldfoot,Chandalar,and Pump Station 113.
Existing facilities such as work pads,highways,access roads,
airports,material sites and communications would be used to the
maximum extent possible.
Socioeconomic and land use impacts related til construction and
operation of transmissi.on facilities between Prudhoe Bay and
Fairbanks will be strictly controlled as a result of the guidelines
and constraints for development within the designated utility
corridor.Cor~struction employees would be housed either at the pump
stations or the permanent camp facilities constructed for the
trans-Alaska oil pipeline.Construction activities would bE:
consistent with the land use criteria developed by the BLMu The B1M
has prepared land use plans lor the utili ty corridor between Sagwon
Bluffs and Washington Creek.Road and highway crossings would be
minimized,and areas of existing or planned mineral development
~ould be avoic~d.
The schedule for constructing the transmi.ssion lines is
approximately 3 years wi th activities occ.l.1rting mainly during the
a.utumn and spring of each year.A peak work force of 2400 ewplo;~~.es
would be required during the first year of construction ~hen the
pads would be built,and in .subsequent years the total work forc~.
would be substantially reduced to approximately 500 in t:he second
year,600 in the thitd year,and 670 in the fil1al yea,r..It is
expected that these workers will be hired from th~Anc!lorag~and
Fairbanks union hiring halls.
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3.2.2 Fairbanks
area significant.The cumulative effects of these facilities cQuld
result in significa.nt degradation of the aesthetic character of
pristine wilderness landscapes as described in previous
discussions.In locations wher(~visual impacts cannot be avoideci
'through careful routing or tower spotting,mitigative measures such
as the use of nonreflective paint or vegetative screening can be
emplDyed.
4086A
In la47se part due to the t.7inter stagnation conditions,the Fairbanks
area is eurrently designated as a nc.\nattainmentarea for CO.
Emissions of CO are largely due to automobiles.The State
Department of Environmental Conservation and the Fairbanks North
Star Borough Airl'ollution Contt:~l Agency are implementing a plan to
reduce the ambient CO mainly through the use of vehicle emission or
traffic control techniques.In addition,relatively high l€:vels of
nitrogen oxides ha've recently been.mon.itored in the,Fairbanks area.
Only an annual average nitrogen dioxide standard exis ts,but the
ahort term measurements of nitrogen oxides are as high as in major
urban areas s~~ch as Los Angeles.
3.2.2.1 Air Resources:A facility located in the Fairbanks aX'ea
would impose critical siting efforts and control technologies to
avoid significant iinpacts.Analyses of the Fairbanks urban "heat
island"have shown that winds are generally light in the winter and
that wind directions change dramatically in the vertical direction
during the wintertime.During the winter months,the a.ir near the
ground is relativp.ly cold,compared to the air aloft.This reduces
mixing of the air in the ve1."ti.c:al direction,and when combined with
relatively l.ightwinds~often leads to periods of air stagnation.•
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Because Fairbanks is a 110nattainm,ent area,the operators of a
facility must demonstrate that they will reduce,or offset,impacts
of the power plant by reduci.ng elllission levels of CO at other
sources.Emissions of CO from s natural gas-fired power plant are
relatively low,and any displacement of the burning of other fuels;
such as coal or oil,will likely lead to improved air quality.This
arises from the clean-burning nature of natural gas andfrorn the
fact that emissions from a major facility will be injected higher in
the atmosphere (due to plulQe buoyancy)than the displaced
emissions..During the very stagnant conditions in midwinter,the
plume from a pot;ler plant.will likely remain well aloft with little
mixing to the surface layers.The complex ul"ban heat island and
associated wind pattern will require a great deal of in-depth
Dlodeling and analySis to deter'Dline air quality impacts in teI'D1S that
will withstand regulatory scrqtiny.
The nitrogen oxides limits at Fairbanks will be the most
constraining atmospheric pollutant.The operation of a power plant
will also consutne a portion of the allowable deterioration in air
quality for nitrogen oxides.While it is possible that the power
plant could be sited near Fairbanks,its installation would
constrain other development efforts which also might consume a
portion of the air quality increDient.The nature,magnitUde,and
duration of emission plumes must be studied as well as the potential
for beneficial impacts due to reduced combustion at other sources
within.the area.
The Fairbanks area is alsd subjected to extended periods of
'Wintertime ice fog,and the Alaska Department of Environmental
Conservation will l'equire the impact of any 'Water vapor plumes to be
carefully assessed.A combustion turbine po'Wer plant 'Which uses
water or s tea111 injection tech~liques would have an adverse impact on
4086A
B-26
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B-27
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~he ice fog and.icing deposition nearby.This emissions control
technology may thus not be feaRtble.This is similar to the
situation tha·t exists at the North Slope location.
To control soil--loss and subsequent sedimentation effects,s.everal
mitigation practices should be used during pipeline construction'.
Existing work pads,highways,access roads,airports,material
sites,and disposal sites should be used whenever possible to
minimize vegeta.tlon disturbance.Pipeline rights""'of-way and access
roads should avoid steep slopes and unstable soils.Hand clea:l'ing
could be used in areas where the use of hea\'"y equipment would cause .
unacceptable levels of soil erosion.A SO-foot buffer strip of
undi.sturbed land could be maintained between the pipeline and
streams,lakes,and wetlands wherever possible.Constructi.on
equipment should not be operate!.in water bodies except where
3.2.2.2 Water.Resources;A gas combined cycle power plant at
Fairbanks will use approximatel of freshwater for boiler
makeup,potable supplies,and miscellaneous uses such as equipment
washdown.Beca.use atnple groundwater exists in the Fairbanks area
and because the water requirements are not particularly large,
impac ts on water supplies in the area will not be significant.
Impaets associated with the natural gas transport system,however,
could be very significant.
4086A
A gas pipeline from.the NO,rth Slope to Fairbanks will cross 15 major
streams and rivers,including the Yukon River,and could potentially
impact numerous additional small streams and drainages.The
pipeline will be buried for its entire length;vegetation will be
disturbed within a 50-=foot wide strip.Without careful siting and
construction practices,erosion from exposed areas could cause
sedimentation pt"oblems in nearby water bodieso
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4086A
The Yukon River crossing wi.ll utilize an existing bridge..The Yukon
River will therefore not be signi:fic.antlyaffected by the pipeline ..
necessary.Where high levels of sediment are expected from
construction activity.settling basins should be constructed and
maintained..All disturbed areas should be left in a stabilized
condition through the use of revegetation and water bars;culverts
and bridges should be removed.and slopes sho\lld be rest6red to
approximately their original contour.
A significant problem wi th the operation of a chilled,buried
pipeline is the formation of aufeis.Aufeis is an ice structure
formed by water overfloWing onto a surface and freezing,wi th
subsequent layers formed by repeated overflow.Chilled pipe in
streams can cause the stream to freeze to the bottom in the vicinity
of the pipe,creating aufeis over the blockage.A chilled pipe
through unfrozen ground can also form a frost bulb several times
larger than the pipe diameter.This frozen area can block
subsurface flow,forci.ng water to the surface and causing aufeis.
Road cuts can also expose subsurface flow channels,causing aufeis
build-up over the roadway.The potential for aufeis and possible
effects will require detailed considerati.ons for all construction
All stream crossing facilities should be designed to withstand the
Pipeline Design Flood as defined.for the ANGTS system.Streams
should be stabilized and returned to their original configuration,
gradient,substrate,velocity,and surface flowo Water supplies for
compressor or meter stations should not be taken from fish spawning
beds,fish rearing areas,ov,erwintering areas or waters that
directly replenish those areas during cri tical periods ..
areas.
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4086A
B-29
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3.2.2.3 Aquatic Ecosyst,em:The location of a facility in the
Fairbanks vicinity will not cause significant impacts to the aquatic
resources at the plant site.The water supply for the power plant
will most likely be obtained from groundwater,and therefore will
not Clffect surface water bodies.Discharges from the plant will be
treated to meet effluent guidelines before being released,so that
fish habitat should not be significantly affected.Discharge
quantities will be relatively low,on the order of 200gpm.
Ibwever,there may be significant impacts associated wi thpipeline
and transmission line construction.
The eransmission line corridor between Fairbanks and Anchorage makes
as many as 100 crossings of rivers and streams and comes within one
mile of numerous lakes and ponds.All of these waterbodies are
important habitat for endemic and anadromous fisherief1 Impacts to
fisheries such as increased runoff and sedimentation could occur
thrQugh .clearing of the right-of....way and \~rossing of watercour.ses by
cons truction equipment.The introductiQll of silt into streams can
delay hatching,reduce hatching success,prevent swimup,and produce
weaker fry.Siltation also reduces the benthic food organisms by
filling in available intergravel habitat"
The potential adverseimpac ts can be reduced or eliminate.d through
c onstruc.tion scheduling.Construction of the transmission lines
during the winter would minimize erosion since the snow protects low
vegetative cover that stabilizes soils.Ice bridges could be used
by construction equipment for crossing spawning areas ll where
pOssible.Otherwise,where equipment would move through
watercourses,constrl.1ction could occur during periods when there are
no eggs or fry in the gravel~
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a)lower stream
A cri tical period for most
streams due to the occurrence of
major spring migrations and
spring spawning (primarily
gX'ayling)e
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B-3D
1 May-20 July
15 April-15 July
1 April-IS July
(eatly breakup streams)
IS April-IS July
(late breakup streams)
Chilled pipes in streams should not cause:
Fairbanks):
Region I
Regi.on II
Region III
ANGTS)is not noted
Divide of the Brooks
The timing of construction is also critical.Adverse impacts maybe
encountered~if the following regional schedule (developed for
(Region I,Beaufort Seato the Continental
Range;Region II,Continental Divide of the
Et>ookg P...ang$to the Yukon River;and Region III,Yukon River to
temperatures so as to alter biological regime of stream;b)slow
spring breakup and delay of fish migration;or c)early fall
free~e"up which would affect fish migration.In addition,the
temperat\1re of surface or subsurface water should not be changed
significantly by the pipeline system or by any construction-related
activities.
A natu.ral gas pipeline from the North Slope to Fairba.nks will cross
numerous rivers andcreel,c.s.including the Yukon River..Aquati,c
resource impacts will include all those discussed above and
addi.tional impacts caused by the chilled pipeline c.rossing
liaterbodies.Several mitigation measures,in addition to those
already discussed,should be implemented to protect the fish habitat
affected by pipeline construction and operation..Stream crossings
should be constructed such that fish passage is not blocked and flow
velocity does not exceed the maximum allowable flow velocity for the
fi.sh species in a given stream.If these criteria cannot be met,a
bridge shou.ld be installed,
4D86A
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A preferred period.for construc-
tion in many streams that do not
provide winter habitat.These
streams generally are dry or
freeze to the bottom duri.ng
winter..This is a crItical
period for fish overwintering
in springs,large rivers,and
lakes.
A sensitive period..Fry of
spring spawning species have
emerged and major fall emi-
grations have not yet begun ..
Fish are mobile at this time and
can move to avoid or reduce
effects of disturbance ..
A critical period for all
streams.Fish must emigrate
from streams that do not
provide winter habitat prior
to freeze-up.Major upstream
migrations and spawning of
fall spawning species occurs
in streams that provide
overwintering habitat.
J
20 July-25 August
15 July-2S August
15 July-l September
1 Dc tober-I May
(small streamf$)
15 Oc tober-l May
(large Ftreams)
15 October-IS April
(small streams )
1 November-I5 April
(large streams)
1 November-l April
(early breakup streams)
1 November-IS April
(late breakup streams)
25 August-l October
(small streams)
25 August-IS October
(large streams)
25 August-l ~tober
(small streams)
25 August-IS October
(large streams)
1 September-l November
Region I
Region II
Region III
Region 1:1
Region I
Region III
B-3l
4086A
For the Fa.irbanks to An~horage transmission line approximately 80
per~ent of the corridor is located in forested areas (Commonwealth
Region I
Region III
Region II
3.2.2.4 Terrestrial Ecology:A power plant in the Fairbanks
Vicinity will affect terrestrial resources primarily through habitat
dIsturbance"Potential power plant sites in the Fairbanks area are
located in developed or previously disturbed areas.The potential
for adv'ersely affecting terrestrial habitats is therefore not
considered to be significant.However,as for aquatic ecology,
there are potential significant impacts associated with transmission
line and pipeline construction.
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4086A
Associates 1982).Assuming two additiO,nal lines lire built and the
Intertfe is extended,a total of about 8,700 acres will be cleared.
The principal impacts associated liith clearing a right-of-way ap,d
construction of the transmission line are the alteration of existing
habita.ts and subsequent disruption of wildlife species that use
those habitats and disturbance to indigenous fauna and bird
populatic>ns.
Most big game species,would relocate cluring the cOIlstruction of the
transmission lines.The construction schedule should be flexible so
as to avoid construction near calving and denning sites during
appropriate seasons.Moose,which adapt to many different habitat
types,avoid the right-of-way construction,but may benefit in the
long-term from the rem.oval of overstoryvegetation which enhances
browse production.The distribution of caribou is lim.ited along the
transmission line corridor but those that do occur in the vicinity
of the right-of-way would be displaced.The caribou,however,
generally utilize habitats with low vegetative cover,resulting in
little alteration of caribou habitat.
:8-32
Grizzly and black bears would relocate to avoid construction
activi ty along the right-oi-way,except where construction occurs
near a den site during winter dormancy..Construction activity near
denning areas should be avoided from October 1 through April 30.
The alteration of habitats could temporarily affect bear use of the
right-of-way but this impact is expected to be relatively short-term.
Wolves within the vicinity of the right-of-way would also be
displaced during construction of the transmission line"While these
impacts would be tempora.ry,long-term.impacts would occur to the
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B-33
I .'.
In heavily forested areas along the corridor,the right-of-way
clearing could provide an improved habitat for most of the small
game sp~cies that utilize subclimax commun:lties.
The impact to regional populations of Ciny of the small game species
is expected to be negligible.Small game species are expected to
relocate during construction activities and reinvade the
wolf if their principal prey species~such as caribou,sheep ,aud
moose were adversely affected.
Dall sheep occur only at the northern end of the transmission line
corridor and would be impacted ~nly minimally by construction
activities.The use of helicopters to construct the lfnesin the
Moody and Montana Creek drainages could severely disturb sheep in
the vicinity of Sugarloaf Mountain.
right-af-way once construction iz over.
Furbearers are not expected to be greatly affected by construction
activities except during the initial right-of-way clearing.Most
furbearers will either ada.pt to the presence of the cleared
right-of-way 'or undergo short-term impa.cts.The maintenance of a
shrub commuuity "in the right-ai-way ~Till reduce the IO$s of
individuals.
Migratory waterfoWl are ""11scepti hIe to disturba.nce from construction
acti'vities from mid~Apri.l to the end of September when ,they are
nesting and brood rearing_Constructior..activities should be
restricted froDl May through Augu,st in areas with active trumpeter
Swan nesting territories.Collisions with transmission lines,
guywires,and overhead groundwires are another potential impact.
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B....34
The impacts on nongame mammals and birds are expected to be
insignificant.Some small mammals and nongame birds would undergo
population shifts during construction activities but populations are
expected to recover within one to two reprodllctiveS$8sons.Raptors
Dlay lolsesome habitat as a result of clearing.Benefits of a
cleared right-of-way could occur as some raptors could find that it
provid$s hunting habftator hunting perches not previously available.
The construl~tlon cfa gas pipeline from the North Slope to Fairbanks
will require total clearing of a 50-foot right-af-way for the length
oi'the gasline.In addition,ten lO-acre compressor stations,two
IIllS-acre metering stations and a gas conditioning facility (15
acres)will be construc.ted.Construction activities will disrupt
terrestrial animals near the corridor d1.1ring the three-year
construction period..The pipeline alignment will avoid the
pex-egrinefalcon nest sites near the Franklin and Sagwon Bluffs.,but
other raptors may restrict construction schedules.Special
construction measures may be necessary in the areas delineated by
theBLM land use'plan,a13 discussed for the North Slope scena.rio.
Construction activities,especially aircraft traffic,could disturb
DaII sheep habitat in critical wintering,~ambing,and movement
ar.eas-These construction-x-elated impacts would be less than three
years in duration-
4086A
Long-teI1tt terrestrial .impacts will result primarily from habitat
elimination.Important moose browsing habitat,such as the willow
stand along Oksrukuyik Creeks should be px-eserved.The treeline
white spr1J.ce stand at the head of Dietrich Valley,which has been
nOl!1ina.ted for Ecology Reserve status,should be avoided.The
pipeline design should allow for free passage of caribou and other
large ardmals,to avoid significant adverse impacts.
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3.2.2.5 Socioeconomic Factors:The rela.tively la.rge population
base in the Fairbanks vicinity preclude!.major impacts from a
boom/bust cycle associated solely with power plant construction ..
The potentia.l socioeconomic impacts are rather associated with
transmission line and pipeline clonstructi~~~::
The size of the construction workfOl~ce fot'thegenerati!'8 facility
is expected to be approximately 200 pe:,zcL1s.These generation units
will be constructed during the summer for about four or five months ..
B-35
4086A
Development of a ~enerating facility on the outskirts of the
Fairbanks area should not engender significant land use conflicts,
since the focus of the final site selection actiVities will be on
areas which are presently used for industrial development.However,
the long-term staged development of a major elec.tric generating
complex will certainly bea determinant of future land uses in the
local area.
Construction activities at the generating plant site will generate
additional worker and construction vehicle traffic loads on the.
local road system.However,disruptions to eXisting traffic
patterns can be minimized through site selection by utilizing major
highways and arterials to the maximum extent possible and by
Since the project could draw on the large labor pool at Fairbanks,
it can be expected that the major!ty of workers will be hired
locally.Economic benef!ts to the region will not be si.gnificant as
emploYment on the project will be temporary.Anyin-migrating
workforce will have to seek temporary housing on their own since
housing will not be provided at the project site.The extent of the
impacts on the local housing supply will depend on the va.cancy rate
for the summer of each year of construction.
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4086A
pre$erve.
B-36
developing a local access plan and schedule<-Depending on the site
selected,neW accessrequlrements will be planned in recognition of
local traffic requirementsc
Land use impacts could include eIlcroachment of the project on
residential areas as well AS preclude future residential development
land available.for homesteading.The m.ost significant potentia.l
impact would be the crossing of recreation lands and the subsequent
effects on recreation and aesthetic values these lands are meant to
Impacts to local communities would be minimized through careful
siting of the temporary liork camps.It is expected tha.t the work
camps would be self-contained in order to keep tb a minimum
interaction between the construction workers and the local
residents.The project is e:xpectedto have minor primary economic
benefits since few,if any,residents would be emplo:~1 On the
project.
Development of additional transmission facilities between Fairbanks
and Anchorage could have potential significant socioeconomic and
land Use impacts,sinCe this segment is moderately populated and
subject.to future land use development.Temporary campsi tes would
be provided to house the work creWs at locations accessible by the
Parks H:1.ghway or the Alaska Railroad.The schedule for constructing
the transmission lines is approximately 22 months.A peak work
force of approximately 520 employees would be x'equired during the
last 6 months and the average work force liould be approximately
300..These estimates do not include the helicopter crews.It is
assumed that the project would utilize the labor pools of Fairbanks
and Anchorage ..
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B-37
__.t.1
4086A
For construction of the gas pipeline in the North Slope~Fa1rbanks
corridor,employee$will be housed either at the pump stations or
the pepnanent camp fac.ilities that were constructed for the
trans-Alaska oil pipelineo Construction activities will be
cons;l.stent with the BlM land use criteria.
3.2.3 Kenai/Nikiski
3.2.3.1 Ai.r Resources:The air resources considerations for this
option would be identical to those already discussed under the Cook
Inlet utilization at this location.However"there are additional
3.2.2.6 Aesthetic.Factors:The Fairbanks area,already containing
noticeable development,would not be significantly impacted by the
construction of a combustion turbine power plant,assuming careful
siting and adequate landscapi.ng criteria are employed.However,the
potent'5.al ae$t:hetic impacts.of the proposed Fairbanks transmission
.facilitiesand/or pipelines are significant..The cumulative effects
of these facilities and previous linear developments (e.g.,TAPS)
could result in significant degradation of the aesthetic character
of pristine wilderness landscapes.The visibility of the
transmission lines from existing "ravel routes (Dalton Highway,
Parks Highway,etc.)will \fary depending on distance,topography and
intervening vegetation.Special ,,~are would be taken in selec.ting
final route al.i.gnments in proximity to areas of sp~cial visual
significance,such as national parks,or high visual sensitivity,
such as arees within the viewing range of motorists on the Parks
Highway.In locations where visual impacts cannot be avoided
through careful routing or tower spotting,mitigating measures,such
as the use of nonX'eflective paint or vegetative screening,can be
employed.
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Moose River
Chickaloon River
L1 ttle Indian Creek
Furrow Creek
Chester Creek
Soldatna Creek
Mystery Creek
Big Indian Creek
Potter Creek
Campbell ~reek
Ship Creek
The water quality of these streams should not be directly affected
if towers will be set back from the streambank at least 200 ft,and
Construction activities stay out of stream channels.Indirect
impacts on the 'Water bodies,however,will reSult from construction
4086A
"f·'··~t'
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3.2.3.2 Water Reslources:The water resources considerations for
the.plant would be identical to those already cii;scussed under the
Cook Inlet utilization of this location.However,transmission line
construction would have signific.apt impacts,whic:h are elaborated
upon below.Potential effects of pipeline construction would.be
similar to those preViously described under the Fail~banks option-
B-38
nl'ture.
secondary ilDpacts toa.ir resources that should be mentioned..These
impa~ts are ase,!}ciated with construction of translDisGion lines,g.as
pipelines and other support facilities..The construction of these
facilities would result in temporary ~ir quality impacts.The use
Of heavy'equipment a~d other construction vehicles would generate
fugitive dust and exhaust emissions.Slash burning of material to
clear the right-of-way 'Would produce emissions.The impac ts from
these construction-re.latedactivities are expected to be SIllall
because the emissions would be widely dispersed and teIIl'poral in
A transmission line from Kenai to Anchorage would crasIs the streams
and creeks listed below:
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act.ivity in the small drainageways that feed the mainchannel r
primarily fr0D11'emoval of vegetation (causing higher erosion rates),
equipme.nt crossings of small drainages,and access road
c·.)nstruction.Becauase helicopt:;r construc.tion will be used along
most of the route,the u~~e of heavy equipment~'Vegetation removal,
andacc:essroad construction should be minimal.
The transmission line will cross Turnagain Arm from Gull Rock to the
mouth of McHugh Creek via seven buried submarine cables.
C-onstruction phase im.pacts will consist of increased turbidit::-from
the cable installation,Cl.nd construction activity near the shore on
both shorelines.Operation phase impacts will primarily be the
potent.ial for cable rupture and subsequent c:able oil contaminatic)n
of Turnagaini\rm.The cable will b~designed to have a very low
probability of rupture over the life of the project.A synthet.ic
cable oil,dodecobenzene,should be used for cable insulation.If
this oil accidentia1J.y leaks,it will rise to the surface and
quickly evaporate when exposed to air.This oil is used
specifically to minimize environmental effects associated with f:
cable rupture-
3~2.3.3 Aquatic Ecology:The water supply at the Kenai/Nikiski
loca.tion will probably come from groundwater Gupply.Therefore,as
noted under the Cook Inlet option,d1rectplant impacts would be
minimal.However,there are additional considerations associated
with support :facilities,especially transmission lines and pipelines.
Soldatna Creek and Moose River flow into the Kellai River system,a
maj()r river for anadromou$fish habitat.Soldatna Creekprov1des
spawning and rearing habita.t for sil~er salmon,and Moose River
contains king)silver,a.nd sockeye salmon (U.Sl!Army Corps of
Engineers 1978).Sedimentation of these water bodies from
4086A
B....39
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4086A
An accidental rupture of a c~ble.would leak cable oil into the
aquat.ic.enviX'Qnment.The cable oil used should be dodecobenzene,as
it rises rapidly to the surface and evaporates when exposed to air,
thereby .m.:lnilIliz;1.ng environmental impacts"
transmission line Qr pipeJ..1ne construction could affect spawning and
rearing habitat in these streams..Because helicopter conEi';n~l!tion
will be used for most of the route,howevex,sedimentation effects
would b~relatively minor.
Impacts to freshwater aquatic reSQurces Yill be mitigated primarily
through the control of sedimentation of water bodies,k(;!eping
construction equipment out of streat11beds and wetlands,and avoiding
areaS of high biological value.
For a facility located at Kenai,cr~ssing Turnagain Arm with
underwater cables poses a~~itional environmental hazards.Tu~nagain
Ann is a.n Lnviromentallysensitive area in the general vic.1nityof
the project that contains marine mammals,including Harbor Seals,
sea lions and Beluga whales fU ..S.Department of COlUlD.erce 1979).
Salmon are present in Some of the small streams that enter this area
(Alaska Depart~ent of Fish and Game 1978).
Installation of buried subxnarine cables will temporarily disrupt the
sea floor along the cable route and increase turbidity and suspended
solids in the vicinity of the crossing.Tidal currents could carry
suspended sediment b~yond the immediate crossing site.Special
construction techniques should be used to tni.nimize disturbance of
the substrate.Inst311atiCln should take place when biological
ac.tivity is at its lowest point in the yea.rly cycle.
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B-41
4086A
The transmission line corridor passes near Chickaloon Flats and
PDtter Marsh on 'lUrnagain Arm.,both key waterfoW'1 areas..Various
pUddle ducks,geese and sandhill cranes fe@d and rest during
3.2.3.4 Terrestrial Ecologt:Impacts to terrestrial ecology for
the power plant would be id.entical to those discussed t'Jnder the Cook
Inlet utilizatS,on option.A power plant in the Kenai vicinity will
be located in an area already extensively ceveloped;little habitat
degradation will occur.The area disturbed for power plant
construction,approximately 140 acres,will not significantly affect
teJ..restrjal resource in the area.
The cables may operate at a temperature level above ambient
conditions.Because the cables will be buried six to ten feet,only
the substrate temperature and not water temperatures would be
elevated (Bonneville Power Administration 1981).
The transmission route passes through an area of caribou habitat
northeast of Kep.ai (University of Alaska 1974).Little alteration
of caribou habitat will result from ~onstruction of the transmission
line because the animal utilizes cover types that require little,if
any.,clea.ring.
Much of the route between Kenai and Anchorage is within moose
rangelant.i.Ilowever,because moose utilize many different habitat
types,they will be the least adversely affected by habitat
alterations (Spencer and Chatelain 1953)..Where the proposed ~oute
crosses heavily forested areas,moose 'Will benefit from add:lt!Danl
clearing of the right-of-way and the subsequent establishment of a
$ubclimax community (Leopold and Darling 1953).The route does:not
cross Dall sheep or mountain goat:habitat~
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seasonal migration periods in these areas.The shoreline of
Turnagain Arm is also used by seals and sea lionso The transmission
line would not directly affect this wildlife habitat but could be a
sour.ce Qf avian collision mortal:i.ty.
Construction of the submarine cable could slightly affect
terrest~ial hgbita.t indirectly by increasing turbidity of Turnagain
Arm and thereby affecting food sources.Thj,s would be a temporary
effect during the construction pha.se only.
The transmission corridor passe~through several vegetation types.
Between Kenai and Sterling,the vegetation is primarily bottomland
spruce-poplar forest.A~corridor extends northeasterly towards
Turnagain Arm,the vegetation becomes upland spruce-hardwood fores t
and,on the foothills of the Kenai Mountains,coastal western
hemlock-Sitka spruce forest.North of Turnagain Arm,the vegetation
is primarily bottomland spruce-poplar forest (University of Alaska
1974)•
Transmission line construction will necessitate clearing a 22D-foot
wide corridor in all forested areas.Over the l~ngth of the
corridor,it .1$assumed that a total of 550 acres would be cleared
within the right-of-way.
3.2.3.5 Socioeconomic Factors:The socioeconomic effects of-----------------
It'~;a,ting a facility in the Kenai/Nikiski area depends primarilY on
the size of the in-migrating workforce.Land use impacts are not
expec.ted to occur as these facilities are compatible wi th the
heavily industrialized development that dominates the Kenai/Nikiski
area.The size of the construction workforce for the gene:ratitlg
facili.ty is expected to be approximately 175 persons.The
construction schedule would require that a unit be constructed every
40B6A
:8-42
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year during the period 1993 to 2010,wIth tbeexception of 1994 and.
1999,when no new units would be required.The duration and time of
the construction period would be fO\lr to five months in the summer ..
The extent to which loca.l people would be hired would depend on the
match of skills required for the project to those skills of the
available labor force.Labor union policies would also influence
the extent of local hires on the project.The in-migrating
workforce would have to seek temporary housing on their own si,nce
h~using would not be provided at the project site.The magnitude of
the impacts on the local housing supply WQuld de.pend on the vacancy
rate for the summer of each year a unit was constructed.
The project is expected to have little effec:t on the unemployment
rate since employment on the project would be seasonal.In
addition,these job openings would be competitive with other
employtIlent opportunities in seasonal inc1;ustries such as construction
and fisheries.
The operations workforce .is expected to be approximately 100.The
magnitude of potential impacts depends on the availa.bility of local
labor to meet the workforce requirements.If the majority of the
employees migrate to the Kenai/Nikiski region,the demand for
housing could exceed the supply.
·Construction of transmission lines between Kenai and Anchorage is
expected to take 22 monthse TIle peak workforce is estimated at 221
persons during the last six months and average construction
workforce is expected to be apprQximately 163 workers.It is
assumed that workers would be hired from the l(fl,or pools of K.enai
and Allchorage.
4086A
B-43
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B-44
302 ..3.6 Aes thetic Factors:The aesthetic considerations would be=
identical to those described under the Cook Inlet option for the
plant location.Transmission line and pipeline considerations would
be very similar to those described for Fairbanks,with the pot~ntial
f or visual degradation •.
4086A
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B-45
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4087A
Few alterations of water podiesare expected during the con.struction
phase of the project-However,alterations may be associated wi th
4.2.1 Construction Impacts
4.0 HY1)ROELE(~TRICFACILITY -CHAKAClIAMNA
The water resource impacts of project development can be segregated
into those associated with project construction activi tes and those
associated with the operation of the facility.
4.2 WATER RESOURCES
The Chakachamna hydroelectric alternati~e has been invest~gated
further than the other alternatives,with site specific preliminary
engineering,feasibility analysis,and monitoring data available.
Therefore,the $cope of the discussions presented.in this section is
in correspondingly greater detail,drawing heavily upon the recent
findings of Bechtel's studies (Bechtel 1983).
4.1 A IR RESOURCES
Hydroelectric facilitiesha"",re minimal impacts to the air resources J
wi theffects restricted to potential localized meteorological
changes associated with creation of a rt:~se-:.'voir..Since Lake
Chakachamna already exists,there will be no first order air
resource impacts anticipated from development of this facility.
The construction related impacts fall into three general areas:
effects of permanent or temporary altet'ations to.water bodies,
changes in water quality associated with the alterations,and direct
effects of construction activities.
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installation of bridges or culverts .for roads and rights-of-way;
rerouting of runoff from camps and materials storage areas;and
rerouting of flow in areas of near-stream or in-stream construction.
Br.idges and/or culverts will need to be installed to provida road
access over streams and other W'aterways.Properly designed bridge.s
and culverts,installed so as to prevent perching and high water
velocities should have few adverse impacts on 'Waterways.During
construction or installation of the bridges/culverts,some local
increases in turbi8i ty and localized disturbance wou.ld be expected fl
but these should be of relatively short duration.
Rerouting of runoff from camps,materials storage areas,and
construction sites is ex:pected to affect small areas,primarily in
the McArthur River canyon..The rerou.ting is expected to primarily
involve rerouting of surface runoff,where silt and soluble
materials would otherwise be carried into the waterbody.Some
rerouting of in-channel flows may be necessary to allow construction
activities itl certain site areas.Presently,there are insufficient
data to identify the extent of these areas.The rerouting of flow
in some construction and camp areas may be .permanent.
There are a variety of water quality impacts that could potentially
occur during construction.These generally involve the discharge of
silt-laden waters from various areas and effluents.Most impacts
due to such d.ischarges can be mitigated,if not eliminated
altogether.
Silt-lader..waters from collected.runoff and from exc.avation of
facilit.ies,could represent a c.onsid.erable source of sil t and
turbidity to the river unless they are held in detention ponds
before being discha.rged~Spoils will be disposed of or stored at
4087A
B-46
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B-47
The primary change itl wat~r quality that may occur from construction
is increased turbidity.This may be produced by increased erosion
associated with disposal of tunnel spoils and construction
actiVities.Turbidity originating f::om runoff and -:6nstruction is
often assoc'iatedonly with artual clearing activities and rainfall
events.The increases in tl.1rbidityin the Chaka.chatna disposal area
would occur near maximum lake levels.Increases in turbidity would
vary with the type,extent):and duration of construction activity,
but would be expected to be local in nature and of relatively short
duration.
the headwater area of the Chakachatna and McArthur rivers.Spoil at
the upper McArth.ur R1 vel"canyon will result from tunneling and
powerhouse excavation.Much of this will be used for construction
of river training works needed to protect the powerhouse tailrace
channel from erosion and damage by the river.The disposal area for
excess spoil will be located so as to avoid significant adverse
effec;ts.Spoils in the Chakachatna River drainage would include
tnClterials retnoved from,the spillway channel,gate shaft excavation,
fish passage facilities,and tunnel excavation.Some spoil will be
used to construct the outlet structure dike,while the excesS -will
be·disposed of in locations yet to be determined and selected so as
tomini~i~e adverse environmental impact.Disposal ares will be
diked,and runoff controlled to minimize sediment discharge into
waterways.Settling ponds will be used for sedimentation of
suspended silts prior to discharge to reduce potential impacts.
The production of concrete for construction of the fish passage
facili ty and powerhouse may result in producti.on of concrete
batching waste,A particular problem with this waste is its high pH
(10+)and the need.to neutralize it (pH 7)pr.ior to discharge.It
is expected that this wa.ste will be treated as required by the
anticipated proj.ect NPDES permit.
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4087A
The removal of ground c:over during this project will be minor but
may locally increase the potentia.l for greater runoff,erosion:-
increased turbidity,and increased dissolved solids.The extent of
impacts can be minimizeed through tho use of mitigative practices to
control erosion and related sedimentation and turbidity.
Direct construction Activities include activities that can be
expected to occur throughtout the construction of the project.
Thes~activi ties,for the most part,will be confined to specific
areas..During construction,some of the first activities to occur
will include the construction of access r()ads~clearing of con--
struction areas,stockpiling of construction materials and fuel,
movement of heavy equipment,and construction of support
facilities.Activities a.ssociated with support facility con-
struction -will include cutting and clearing in areas near several
streams~
B-48
During peak construction activity,facilities to house workers will
be located primarily in thll~McArthur floodplain.The housing and
supply stor'age area will occupy 20 to 30 acres.Due to the presence
(If a large construction force in the area,sanitary waste 'Will need
to be treated and discharged.
There are no pla.ns for regular operations of heavy machinery in
streams.The primary use of heavy ma.chinery would be during the
rerouting of flow.The extent of potential impa.ct due to siltation
and turbidity should be short term and dependent upon the extent of
machinery operation and the type of substra.te in the streams
affected.Smallet substrates tend to be more aff~cted.However,if
water velocities are sufficiently high,the dEy-osition of suspended
sediments may not OCClJ.r locally,and the effects would be minor.
Current conStruction plans do not require j,ns tteam blasting.
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As part of the construction activities,water will be diverted from
strea.ms in the construction area to be used for dust control,
drinking water,fireafighting water,sanitary 'Water,concrete
hatching,and wet proeessing of gravel among other uses.The
diversions will probably be accomplished by pumping from local
stream segments and intakes will be screened and designed to use
very low "tJelocities to avoid fish impingement and entrainment ..
4.2.2 Operational Impacts
The potential impacts to water resources from the operation of the
Cl-akachamna alternative will vary for the three general water
bodies;Chakachamna Lake and tributaries,Chakachatna River,and
McArthur River.
Chakachamna Lake will be affected by a 72 ft annual water level
fluctuation duri.ng proposed project operation.The maximum proposed
reservoir level of 1155 ft is near the maximum historical lake
level;this level will occur seasonally u,1der post-project
conditions.Minimum reservoir levels will be apprOXimately 45 ft
below pre-project minimum levels.Such a drawdown will expose lake
shoreline and stream deltas which are normally inundated..Lake
levels will vary in ChakachamnaLake and will .resul t in increased
inundation of lakeshore and delta areas during high reservoir
levels;dewatering of submerged shoreline would occur during periods
of drawdown.
The projeeteffects on the wa.ter quality of l"ake Chakachamnamay
.include increased suspended sediment and turbidity concentrations
near tributary mouths.The potential sediment infloW'froJIl the
tI:ibutaries is discussed below ..
4087A
B-49
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B-50
4087A
According to the proposed reservoir operation schedule,the
reservoir will be at maximum level during September and drawn dolJn
to lower levels over the winter with a minimum level occurring
during Apr!l or May.
The channel gradient of the Chakachamna Lake tributaries will be
affected by the drawdown and fluctuation of the .reservoir level"
Maximum water levels will cause inundation of the lower reaches of
stre(:',ms which are net normally affected;minimum water levels will
expose the entire stream delta surface and th~upper portion of the
steep delta front.Resulting changes in stream gradient will be
progressive and sequential.These will likely be similar at the
mouths of all tributaries,but to different degrees.The
anticipated changes due to s.easonal minimum reservoir levels
2include:dewatering of over 7 mi of delta a.rea;increase in
stream gradient and accompa.nying erosion where the stream flows down
the front of deltas;development of new deltas;eventual channel
degradation at the tributary mouths to near the lowest regulated
reeervoir level;and degradati\:\n upstream as far as Ie required for
the stream to reach equili.brium between the streamflow 1~\:1gimeduring
lOl¥reservoir levels and the materials through which it is flowing,
possibly resulting in localized rapids during the low water period,
if erosion resistant materials are reached.
Maximum reservoir levels can cause deposition 01:stream-borne
sediments in those reaches of stream affected by backwater from the
reservoir.Some of the deposited sediments would likely be eroded
as the reservoir lErY'Ed drops through the winter.Breakup flQwS may
remove the rest of the deposits.
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B-.51
The sedimentatioocharacteristics of the Chakachatna River syst.:am
will change with the required flow regime.Sedimen.t transport will
drecrease in response to decreased flows.
4087A
Water releasesw:lll be made to the Chakachatna River below the fish
passage facility.The quantity of the actual releases is not
presently known,however,preliminary release flows have been
estimated (Table B-1).Such flows constitute a'relatively small
percen.tage of pre-project annual .flowe Tributary inflow downs.tream
from the lake contributes relatively ,-,mall quantities of flow
eompared with pre-project flows at the lake outlet.However,
depending upon the time of year~the tributary inflow may
substantfally increa.se post-project flows downstream of the release
structure.Historical low flows will be substantially reduced by
project operation during October through March.Ten percent of the
average annual flow is considered to be the minimum for short term
survival of fish and other aquatic organisms (Tenn!1I1t 1975).
However,in this system,post-p.roject releases from January through
April may be less than 10 percent but still represent between 60 a.nd
122 percent of pre-project average monthly flows,respectively.
Flood flows would be modified in the regulated flow regime.
Chakachatna River flood flews would be smaller in magnitude than
past events,but would exhibit a greatervax;iation around a mean
flood value due to the relatively sm.a.ll influence of Chakachamna
Lake on the post....project river system.The seasonal distribution.
and hydrograph shape of the ann.ual floods may shift during the
mid-summer,lon.g duration floods under the natural flow regime,
toward a .faI1,ShCN:t duration flood more typical of basins within
the storage effects of lakes and glaci~rs.
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365
363
365
357
365
1,094
REGULATED!I
(cfs)
613
813
505
2,468
15,042
NATURAL
(ers)
3,645
1,206
TABLE B-1
NATURAL ANI>ALTERNATIVE E REGULATED MEAN MONTHLY'AND
MEAN ANNUAL FLOW ATI THE CHAKACHAMNALAKE OUTLET
B-52
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Jan
Jun 5,875 1,094 "'-
Ii ~Jul 11,950 1,094
~.)0
Aug 1.2~,000 1,094
Oct
Feb
MONTH
Mar 445 358
>),-:
Apr 441 582 ./
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¥..:ay 1 ,052 1,094
Sep
Nov
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MEAN ANNUALF,t.oW
Dec
4087A
11-Regulated flows were estimated using the Montana Method.
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The confi.guration of certain stream reaches would likely change as a
result of the flow alteration associated with the project.The
Rountainousreaches on the Chakacha tna Rivet'would retain.a s1 ngle
channel steep gradient condition,although it would be carrying less
flo.w.Sp'li t channel reaches would likely assume more of a
meandering configuration.The braided reaches above Straight Creek
and in Noaukta Slough would likely b~come more stable and the flow
would be carried by fewer channels which are characteristics of a
split configurati.on.The loltterreaches of the Chakacha tI1a and
Middle rivers would likely retain their meandering configuration.
Ice formatj~on and breakup processes will also likely be affected by
the project.The e.valuation of the nature and extent of these
effects has not yet been inve._igated.
Observations made during March and October 1982 have indicated that
flot¥"i.n sloughs located ill the Chakachatna River canyon and at
station 17 appear to be independent of river flow.It is not
expected that reduced flow in the river will have an adv~rse effect
on these water bodies.
The McArthur River will receive flows from the powerhouse ranging
from amillimum of approximately 4600 cfs in July to a maximum of
approximatl~ly 7500 cfs in De ceII1ber 0 Present flows in the \lpper
l-lcArthurRiver near the powerhouse are estimated to average about
600 cfs in July and 30cfs in December.Thus t fll..1wS in this upper
section will be substantially increased by the,opera.tion of the
pro ject during the entireyear~The relative magni tu.de of increase
will be less downstream of its confluence with the Blockade Glacier
channels.Post-project summel;flow in the ~lcArthur River downstream
of its confluence with the NOaukta Slough will be less than
pre-project conditions due to the substantial decrease in flow
through Noaukta Slougb.
4087.A
B-53
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4087A
B-54
The upper McArthur River will e2Cperience increased sediment
transport loads due to the larger discha.rges in the channel.The
upstream "',:'aches will likely scour the channel bed to reduce its
gradient.In addition,bank erosion will likely increase its ra t.e
and areal extent as a result of the increased flow.Flood
discharges in mid....September 1982 caused bed scour and bank erosion,
and transported large quantities of sediments along its channel.
The 1Ilagni tude of this short duration event y;as erproximately 50
percent greater than those expected on a daily basiS under
post-project conditions.
Floods on the McArthur ltlver upstream of Noaukta Slough would be
increased by the operation of the project.The amount of increase
will be 'I")ughly equivalent to the modifi.cation of the base flows
upon which the floods are superimposed.That is,the source of the
flood waters remains unchanged,but the floY in the McArthur River
as the flood begins wi.ll be greater"The relative increase in flow
would decrease in a downstream direction along the McArthur River.
Below its confluence with Noaukta Slough.the M~rthur River would
likely experience a reduced flood magnitude.This is due to the
decrease of inflow from Noaukta Slough during the S\lmmel'as compa:red
with the inflow under pre-project c:ortditionso Noaukta Slough
contributes a greater mean dail~.flow to the McArthtir River from
mid-June th.rough mid-September under pre-project eoucations than the
maximum that will be diverted ti>tile MacA.rthur River for power
generation during project operation.
The increased post-project flows .in the McArthur River are not
anticipated to causesi.gnificant changes .in channel confi.guration.
However,some mea.ndering reaches,especially toward the ups treat!!
end,may assume split channel charact.eristics.Further analysiS is
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required to ascertain the effects on channel configuration,of the
increased sediT420t transport into the lower reaches of the McArthur
River.
The ice processes.in the McArthur River will also likely be affeced
by the project.Ice formation may be reduced or possibly eliminated
by the increased quantity and temperature of flow.Evaluation of
these effects requires further study.
Turbidity in the McArthur River canyon would be expected tcincrease
during the winter months.Pre-project rd.nter flow in that area
appears to be der';.lJ't~~from upwelling andi.s clear.Water froIn the
powerhouse tailrace would be expected to have a higher turbidity as
is normally found In Chakachamna Lake.Turbidity in the lake varies
wi th depth dUi'ing certain times of the year but is generally similar
to that measured near the powerhouse location in the McArthur
River.Below the McArthur canyon,flow from the Blockade Glacier
,channel is also turbid and therefore effects below the confluence of
that channel should be minimal.
Pre-project water temperatures in the vicinity of the proposed
powerhouse location have a wide diurnal variation during the open
water season.The discharge of Chakachamna Lake water during
operation would tend to stabilize the temperatures.Water
tt!mperatures at the proposed lake tap depth were as follows:March
-2.1°C,August -6.5°C,September -6.2°C.The temperature of
discharge water should be fairly constant and should reduce diurnal
variation.
There rna:}!'be a potential for the discharge of dissolved gases at
levels greater than 100 percent of gas saturation at the
powerhouse.Water d.ischarged at the powerhouse,entrained at lake
4087}"
B-55
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B-56
4087A
tap depths of mvre.tban 100 ft.,will undergo a pressure.c.hangeof
more than 3 attllospheres.The change in pressure will reduce the
amount of gas that the water will hold,thus creating the potential
for supersaturation to occur.Evidence of a potential for
s.upersaturation was detected d.uring sampling in September 1982.
Si ting of the dam at the mouth of the canyon would result iIi the
loss of slough spawning habitat for c.oho,pink,sockeye,and chum
salmon and Dolly Varden in that area.
4.3 AQUAT.IC ECOLOGY
If a dam was constructed and operated on the Chakachatna River,it
is likely that substantive ad\rerse impacts would be inflicted on
fish of the Chakachatna drainage.A fish passage facility would be
necessary to preserve stocks of anadromous fish which spawn above
Chakachamna Lake.If such passage was not provided,the 41)000
sockeye which are estimated to spawn above the lake and their
contribution to the Cook Inlet Fishery would be lost.The Dolly
Varden population which migrate to and spawn in tributaries above
Chakachamna Lake would also be lost.If passage was maintained,
impacts;;to those populations could be similar to Alternative E.
The potential impacts to aquatic ecology :resources from the various
alternative developmentsc.enarios for the Chakachamna Hydroelectric
Project are a significant factor in arriving at the preferred
development scenario (Alternative E)e Therefore,potential aquatic
resource impacts from these scenarios are briefly deseri bed below,
followed by a detailed discussion of the preferred alternative.
4.3.1 Chakachatna Dam Alternative
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4.3.2 McArthur Tunnel Alternatives A and B
B-57
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4087A
The major difference in these McArthur tunnel alternatives is that
in Alternative A,no water would be provided in the upper reaches of
the Chakachatna River,while in Alternative B,some flow t\Tould be
maintained.Alternative A would likely result in a total loss of
the population of sockeye salmon which spawn upstream of Chakachamna
Lake.The estimated escapement of sockeye upstream of the lake was
41,000 fish during 1982.This would also cause the loss of their
contribution (preslently unknown)to the Cook Inlet fishery.In
Once in opera.tion,the increased flows in the McArthur River may
result in changes in water quality and alterations in the chemical
cues that direct anadromous fish to their spawning grounds.This
could cause additional losses of spawning adults or reduce the
productivi ty of spa~ing areas through crowding and redd
superimposition.Although the possibility also exists that the
population of salmon will increase in the McArthur River,predation
may also increase.If large mammals begi.n to concentrate in these
high density fish areas"sport and subsistence hunting pressure will
probably also incr.ease.
Through the implementation of Alternatives A or B,the impacts..
resulting from construction and logistical support activities would
be very similar.
Due to the water quality alterations in the river downstream from
the dam,the use of some fish migratory and rearing habitat may be
reduced.This,in turn,could adversely impact Cook Inlet
commerc.ial fishery resourCes.Construction iDlpacts fzom this
alternative would be more extensive due to increased area and
materials requirements.
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4037A
Alternative B would provide for year round flow releases to -the
Chakachatna River.Instream flows selected are approximately 30
percent of the average annual flow during May through September and
approximately 10 percent of the average annual flow during the
winter months,O!:tober through March.April flows are
interl'.nediate.The implementation of Alternative B should inflict
less ad\7erse impacts On the fish which spawn a;ld rear below the lake
than Alternative A.The severity of adverse e.~fects upstream of the
lake would depend on reservoir operation and the mitigative measures
taken.The influence on the human resources will probably also be
less severe since the commercial fishery will probably not be as
heavily impac.ted,but the.impact due to the loss of a portion of the
lake tributary spawning could be substantial.
addition,because no maintenance flows would be provided below the
lake,the spawning,rearing,and migration of salmon and resident
fish in the ChakachatnaRiver drainage would likely be significantly
a~d adversely affected.Estimated escapement of salmon below the
lake is over 16,000 fish which could be lost.In Alternative A
thete is a significant potential to drastically reduce the
populations of salmon which are represented by the estimated
escapement of over 57,000 salmon in the Chakacbatna drainage.
Alternative A provides no fish passage to and from the lake.The
sockeye salmon and Dolly Varden which spawn above the lake would not
be able to ascend to the lake unless the }.ake level exceeded the
present channel invert (El.1128)by at least 1 it at the lake
outlet.Downstream migrants eould not pass from the lake u,nless the
water was at this level of if they passed through an outlet
structure which would provide the mitigative flow.The impact of
tht.s alternative without provision for a fish passage structure
co~ld be substantial.
B-58
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While the impacts related to Alternative A affecting local resources
would be difficult to mitigate and significant changes in both the
distribut.ion and abund~nce of fish and wildlife populations would
almost certainly occur,the impacts resulting from AlternativeB
would be less severe primarily through the installation of fish
passage structures and maintenance of adequate downstream discharge ..
It should be noted,however,that while not directly stated,the
loss of spaWnin~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 juveniles of all species provide food (prey)
for other species,losses of spawning and nursery areas will almost
certainly result in eventual reductions :tn 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.
4.3.3 Chakachatna Tunnel Alternatives C and D
Through the implementation of AI ternatives C or D,the impacts
resulting from logistical support or construction activities would
be similar.However,since all activi ties are restricted to the
Chakachatna floodplain in these alternatives,the resources in the
McArthur drainage will not be affected.Significant impacts will
occur to the fisheries..Since access to Chakachamna Lake will be
incr.eased,sport and subsistence fishing pressure may increase.
During the pre""'Operationalphases)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 andChakachamna Lake fishery will be dependent on
4087A
B-59
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4087A
B"'60
4.3.4 McArthur Tunnel Alternative E
Construction and operation of the proposed Chakachamna Hydroelectric
Project will result in changes to the aquatic habitat and associated
fishery resources in the McArthur and Chakachatna rivers,Lake
Chakachamna,and tributaries upstream of Lake Chakachamna,such as
the Chilligan and Igitna rivers.
whether flows are maintained and fish passage facilities provided.
Alternative C does not allow for these mitigative measures.
Therefore,the impacts to the fishery in or above the lake,and thus
the wildlife and commerci~l fisher~F in the surrounding area will be
similar to that inflicted ~hrough Alternative A.Since Alternative
D does provide flows and migratory passages,the impacts would be
similar to those described for Alternative B,but with substantially
less adverse impact below the powerhouse due to.the higher flows
released by that facility.
The construction impacts focus primarily around increased turbidity
and sedimentation.Increased turbidity can reduce visibility and
decrease the ability of sight-feeding fish (e.g.J salmonid.s)to
obtain food •In addition,salmonids may avoid spawning in turbid
waters,and many fish,particularly older life stages,may
completely avoid waters containing high turbidity.However~the
turbidity increases in mainstem areas of the Chakachatna and
McArthur riv.ers would be expected to have a lower potential for
adverse effect on fish due to the naturally high turbidity levels
found in these water bodies.
Siltation (sedimentation)is often associated with construction
activities.Siltation and turbidity itnpacts have their greatest
adverse effects on eggs and larval fish.In general,siltation can
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!Lake levels will bfl near minimum level at breakup,at which time the
principal movement of fIsh consists of emergent fry moving from
their tributary rearing areas to the lake.It is not expected that
the high gradients to the lake will adversely affect these migrants-
cause a significant loss of incubating eggs and pre-emergent fry in
redds.This is generally a result of interference with water and
oJtygen exchange inredds.Upwelling flow in affected areas may tend.
to reduce such impacts by reduci ngthe amount of sediment which
settles into the redd.
Operation of the camps will also result in increased access to an
area that has previously experienced relatively little fishing
pressure.The areas potentially affected would be those stretches
of the McArthur River and its tributaries that are easily accessible
by foot from the camp.
B-61
The operation of the reservoir will have effects on the fish rearing
habitat within the lake.During open water,juvenile sockeye,lake
trout ,round whi tefish,ttnd Dolly Varden are found throughout the
lake with many fIsh found offshore along steep dropoffs and just
under the ice in winter.It is unclear what the effect of changing
water levels may have on.winter water temperatures or habitat use,
parti.cularly near shore.
4087A
At high reservoir levels (during October and November)lakeshore
areas ~ay be used as spawning habitat by lake trout~After
reservoir levels drop,inCUbating eggs and fry may be exposed t.o
freezing or dessica.tion..~.(elativelyimmobile invertebrates which
reproduce in shoreline areas m.ay also be affected.There are,
presently.insufficient data to assess the impact of such effects on
lake trout populations and standing crop of benthic invertebrates,
although the effects could be substantial.
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4087A
B-62
During the pe.riod in wh!ch sockeye salmon and Dolly Varden spawn in
tributaries above the lake,reservoir levels will be greater than
pre-project lake levels.This ~ill potentially result in lake water
flooding downstream areas of the Chilligan River and the Ken!buna
Lake/Shamrock Lake rapids.The effect of the lake water on the
utilization of the lower areas of the Chilligan River is not
presently known but there is SOlDe evidence that this may not be an
important effect.The area at the mouth of the river contained a
low density of spawning sockeye compared to areas .further v.pstream"
It was used extensively as a milling area.During September 1982,
lake water inundated the.area wi thout apparent impact on ei ther
sockeye.or Dolly Varden spawning.Adverse effects would be expected
if flooding of the lower Chilligan River resulted in increased
siltation which could affect hatching success.
Hydroacoustic observations of fish distribution in the lake have.
indicated that most fish were detected well above the depth of the
lake tap.During the winter,over 99 percent offish were detected
i11 the upper 50 ft of the water column.During September 1982,over
88 percent.of the fish detected were in water at least 60 ft above
the proposed lake tap (at that tilDe of year!t would have been
located at 181 ft)wi th no fish detected below 161 ft.Thus,
The lake tap (or multiple lake ta.ps)will wi thdraw wate.r at
approximately EI.9.74.The submergence depth would vary between 109
ft and 181 ft •Fish that are entrained into the lake tap would be
exposed to turbine passage at the powerhouse and most would be
expected to be.killed by the turbines,or during passage through the
pressure differential between the depth of the lake tap and the
power plant.Juvenile sockeye and both juvenile and adult lake
trout)Dolly Varden,and round whitefish may be vulnera.ble.
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4087A
If the facility did not successfully allow the migration of sockeye
both ups.tream as adults and downstream as juveniles,then some part
of the estimated adult spawning population would be expected to be
lost,as well as a portion of its presently unknown contribution to
the Cook Inlet fishery.
33-63
Sockeye salmon and Dolly Varden would be expec.ted to use this
fa.cility,as both have been.observed to spawn aboVe the lake.
Escapement estimates of sockeye indicate that (based upon 1982 data)
over 41,000 sockeye (possibly more depending upon yearly variation)
would need to successfully pass through the fac.ility to migrate
ups tram.Sincs the percentage of the run successfully reaching the
Chilligan and JgitnaRiversis not known,the true extent of the
sockeye salmon resource can only be estimated.From 10 to more than
100 times as many sockeye can be expected to migrate dOlt.lIlstream due
to the normally higher production of young fish.A smaller number
of downstream Dolly Varden would also be expected to pass through
the fac!li ty..If the facility works as planned the impact to the
sockeye run should be low.
potential loss of i.ish due to the lake tap based upon current data
would be rela.tively low.However,additional seasonal information
~ould be needed to quantify potential losses.
This alternative includes a fish passage facility which is designed
to perm.it upstream migrants to ascend from the Cllakachatna River to
the lake and to allow downstream migrants to pass from the lake to
the Chakachatna River.The facility is composed of components found
in a variety of eXisting fish passage facilities.Presently,there
are insufficient data available to assess the potential effects of
this facility on migra.ting fish in a.quantitative manner.
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4087A
The release of water from Chakachamna Lake into the McArthur system
could poeentiallYl:'esult in impacts to fish IJhich would normally
spawn in Chakachamna Lake and tributaries above it.While the
"homing"of salmon is not completely understood,the orientation of
upstream migrants to olfactory cues originating in natal streams has
been considel:'ed tD be a principal factor.Fish entering the system
through the Middle River should not be affected by the McArthur
release.Fish entering the system through the mouth of the McArthur
River may encounter olfactory cues from flows enteriIl8 the McArthur
River at the confluence of the lower Chakachatna with the McArthur
River,from the confluence of the Noaukta Slough with the McArthur
River,and from water discharged from the tailrace of the power
plant located in the McArthur canyon.Fish that entered the
Chakachatna River either at the lower river confluence,or the
Noaukta Slough would be following what i.8 hypothesized to be the
present migratory pathway and would not be expected to be
significantly affected by the other power plant discharge;some
delay due to confusion may occur.There is a potential for some of
the upstream migrants to be attracted to the tailrace in the
McArthllr canyon.Since the fish could not migrate further'ups tream
into Chakachamna Lake,three basic scenarios could develop:the
fish could back down the system until they detect alternate
olfactory cueS (i.e •.,at the Noaukta Slough)and then migrate up the
Chakachatna River;the fish could mill in the tailrace until
sexually matured and then back down the system until alternate cues
were detected;or the fish could spawn in the McArthur Canyon.
The significance oia delay in migration is not presently known.
However p the spa.wning of large numbers of lake tributary origin
sockeye in the McArthur River canyon area would result in low egg
hatching success due to high densities of spawning fish and
resulting redd supel;lmposition,the use of poor spa\\"Iling habitat,or
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4087A
felllales not spawning.In addition,the rearing habitat in the
McArthur canyon is probably less suitable for sockeye salmon than
Chakachamn.aLake.Thus,if increased spawning occurred in this
area,rearing would prObably be less successful.
.a~sed upon 1982 observations,the milling areas at Tributary 01 and
at the mouth of the Chakachatna canyon Sloughs would be
significantly le..;.s turbid than at present.This may also increase
potential VUlnerability to increased p:redati"n"The extent of the
potential increase in vulnerability to predation of spawning a.dults
Side channels in the Straight Creek mouth area and a.t station 17 are
expected to be most affected.Observations during 1982 have
indi.cated that these areas will probably not be dewatered or
perched.The observations have indicated tnat turbid !!1ainstem
overflow,which is present in these areas during higher flows,would
be absent.Without the cOver provided by this turbid flow,fish
spawning in these areas may be more vulnerable to predation.Side
channel.spawning in both areas represents less than 50 percent of
o bserved spawning at each Bite.Depth of water at en.try poincs to
side channels at station 17 would be expected to be shallow and may
adversely affect fish entry •
The mainstem habitats a.ppear to be currently used as migra.tory
pathways,rearing areas for sub-adult and resident fish,and there
appears to be a small amount of side channel spawning associated
ll1ith areas of upwelling or slough flow.Table B-2 lists estimated
escapements of fish species for water bodies in the Chakachatna
River drainage,classified as to whether the water body is likely to
be affected by the reduced mainstem flow_The tributary water
bodies are not expected to be significantly affected by reduced
flows.
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POTENTIALLY NON-AFFECTED WATER 10DlES
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2,781 38,516 0 254
0 0 0 1.422
0 0 0 1,925
0 0 0 0
0 0 0 112
X X X
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TABLE B-2
lSIIE
Chakachatna
Canyon
Sloughs
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POTENTIALLY AFFECTED WATER BODIES
Hore Affected Less Affected
Chakachatna
Bridge
SideChannels
andSlougits
203 1,193 392 238
0 0 0 0
0 59 279 0
152 1,482 121 165-
76,1,560 608 183
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ESTIMATED ESCAPEMENT OF nUURTANT FISH SPECIES IN THE CHAKACHATNARIVER
SYSTEK BYWATER BODl CLASSIFIgD BY POTENTIAL EFFECTS OF DECREASED FLOW OF WATER FROM CHAKACHAHNALAKE
Straight
Creek
Houth
..
Coho
Salmon
Pink
Salaon
Chua
Sa1aon
Chinook
Sal.on
DollY
Varden
Speeie.
Sockeye
Sa Ilion
1/X"Used as spawning areall.
4067A---
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There are a number of fish species which use mains temand side
channel areas as rearing habitat.The effect of decreased flow on
the availability and suitability of this habitat cannot be
determined at this time.While decreased flow will decrease the
wetted perimeter and therefore the area.of the stream,the decrease
is not linearly proportional to the decrease in flow.Additional
sources of inflo~,including sloughs and tributaries such as
Straight Creek,shOl1ldresult in somewhat increased flow downstream
0;;the outlet structure..The additional water sources (Straight
Creek,various sloughs,and unnamed tributaries)will reduce E:ffects
of the.decrease in upstream releases.In areas where pre-project
water velocities are too great to contain suitable rearing habitat,
decreased velocities could potentially increase sui table hab!tat.
Presently j there are insufficient data to evaluate all expected
changes ..
B-67
4087A
at these sf tes will need to be assessed after more data are
collected ..
Downstream migrants originating in the Chakachatna drainage may
require high seasonal breakup flo~s to trigger their migration;
proposed post-project discharges may not be sufficient to trigger
this behavior.However,post-project releases during April and May
a.re greater tha.n pre-project flows and depending upon the tixningof
Decreased flows duri.ng winter may cause changes in the ice
conditions and also result in decreased overwintering habitat.The
actual nature and extent of effects cannot be determined from
available data but a significant decreaSe inmainstem overwintering
habitat is likely during the early winter.TIlf:.'overltlintering
habitat in sloughs should not be affected by reduced flow in the
mainatem of the river.
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Table B-3 lists escapement estimates of major species that spawn irt
the McArthur River drainage by water body.The only area in which
spawning habitat of these species is likely to be affected is in the
McArthur canyon.All other listed areas are tributaries.Spawning
habitat in sloughs cHid side channels of the McArthur cartyon occur
upstream of the powerhouse tailrace..It is unlikely that these
areas will be significantly affected.Based upon 1982 escapement
estimates,a relatively small percentage of spawning salmon will be
vulnerable to changes in mainstem flow.Some fish that normally
spawn above Chakachamni:t Lake may be attracted to the powerhouse
tailrace which may affect spawning adults of McArthur ori.gin.
Mainstem areas of the McArthur lU.ve~appear to be used as migratory
pathways for sub-adult and residential adult rearing,and for
spawning in the McArthur River canyon.
outmigration may be sufficient to trigger the downstream movement.
Data collected during 1982 suggest thatoutmigration of chum salmon
and some sockeye occurs during late May and early Jun.e.Collections
made during the summer and fall and in the Susitna drainage suggest
doWnstream migration and smoltification of coho,chinook,and
sockeye salmon continues throughout the summer and .fa11.Overall,
available data do not suggest that an adverse effect would be
expected on stimUlation of downstream.Dligration.
Eullichon spawn in the lower reaches of the McArthur River Irlainstem,
below the Noaukta Slough.FloW'alterations are not expected to
The redistribution of substrate in the powerhouse a.rea may also
affect spawning.Presently,there are irtsufficient data to
determine if the effect would be beneficial or adverse to the
availability of habitat to spawning adults.
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ESTIMATED ESCAPEMENT OF IHPORTANTFISH SPECIES IN THE MCARTHUR RIVER5YST£H
BY WATER BOOY CLASSIFIED BY POTENTIAL OF INCREAsED FLOW OF YATER
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POTENTIALLY NOH-AFFECTED AREAs
Strealls
Stream 130 Combined 12.1 12.2 12.3 It;'12.5
1,213 27,636 16,111 2 6,085 2 2,512 2 2,328 2
1,633 22 -22 3
5,402 10,090 8,499 2 1,566 2 4 2 18 2 3 2
23 1 5 1 4 5 --1 5
32 1 2,131 I 2,000 1 46 I 89 I
X X X X X X Xx
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452
4,225
1,378 1
5,416
Stream 13X
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666 1
1,182 I
McArthur CanYQn
POTENTIALLY AF.FECTED AltEA
Dolly
Varden
Coho
Salson
Chinook.
SallllOQ
Sockeye
Salaon
Pink
Sal.on
Chua
Salaon
Species
1 Ba~ed on 10 day stream life•
.lilli.sed 006 day streaa life.
3 Based on count of live and dead fish.
4 Based upon 10 day stream life.
S Based On peak on total counts.
6X •Probably spawning areas.
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4081A
B-69
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Water discharged from the powerhouse will probably be warmer tha.n
water of McArthur origin;2.1 °C,as compared wi th 1.2°C,
respectively,during March 1982.This may result in g~t"eater
metabolic activity by fish and other aquatic biota during the
wi.n.ter,and result in more rapid incubation and earlier emergence
times for McArthur canyon fish.Such emergence times would be
similar to those found in the Chakachatna River.It is unclear from
present data whether tois will have an adverse effect.
a.ffect spawning o.f this species because during the period of
eulachon spa.wning,the e.ontinuedpoat-projec t McArthur River and
Noaukta Slough flows are e~pected to be similar to pre-project flows.
There are a number of fish species which use mainstem habitats in
the McArthur River for rearing hah:'tat.Presently,the effeet of
changes in the flow regime in different reaches of the river at
different times of yea.r cannot be determined..Changes in wetted
perimeter,depth,and velocity fat'different areas will aff~et the
overall total suitable area for each species and life.rH.:age.Thus,
suitable habitat may increase,decrease,or remain the same.This
will also need to be assessed.
In~reased flow in the McArthur canyon from the power plant discharge
ma.y affect available ovel"'Wintering habitat in the McArthur
drainage-Data collected during 1982 indicate that the McArthur
canyon and areas belQw it may be used as ~verwin.tering areas.
Increased flow and depth may increase th~ovet'vintering area
available.Insufficient data are available to asseS6 such changes.
Increased post-project turbidity during the winter months should not
have a significa.nt adVerse e'ffecton fish in the McArthur canyt)n.
Turbidity levels should be similar to those measured in this at ea
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during the spri.ng through fall,a.nd it would be expected that fish
are well adapted to them.
If supersaturation occurs it could have adverse effects on fish in
the immediate area of th€discharge unless mitigative measures are
taken.Some sloughs in the immediate vicinity of \'he tailrace of
the power plant may becomG inundated and water velocities may
increase.These changes may affect the suita.bility of these
habitats..The extent of such changes cannot be determined at this
time.No significant changes would be expec.ted in Mc..J\rthur River
tributaries due to post-operational flows based upon current data.
4.4 TERRESTRIALECOLOGY
The development of a hydroelectric.power project at Chakachamna Lake
will result in changes in the distribution and species composition
of vegetative communities.Based upon currant designs for
Alternative E t these changes would occur over a relativel~r small
portion of the project area.Changes that do occur may be
beneficial or detrimental to the biota depending upon the type of
changes as well asthelocatioll,duration,and magnitude of change.
Construction of a rockfill dike and fish passage facility in the
upper Chakachatna River canyon and a powerhouse in the McArthur
River canyon will necessitate the removal of vegetation over a
relatively small area.The powerhouse and fish passage facility
will bepI."imarily underground,thus minimizing surface disturbance.
The rockf ill dike will be sited in the upper reach :_eJ.the
Chakachatna canyon where the floodplain is unvegetated and the
canyon walls and glacial moraine support Sitka alder and willow
which at'e abundant throughout the project area.The areal extent of
vegetation removal during road,camp,airstrip,and bor:rowpi t
4087A
B-71
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development is not yet known because the location and size of these
facilities have not been sufficiently defined.
The most notable changes in the distribution of vegetation will
likely occ.ur in the lower McArthur River and Chaltachatna River
canyons 0 In the lower McArthur canyon,increased flows emanating
from the tailrace and the deposition of excavated materials within
the floodplain near the powerhouse may reduce the e:x:tent of riparian
vegetation.In the Chakachatna canyon below the ci.LKe,reduced flows
may enable riparian vegetation to become established wi thin what is
now the active floodplain.In time,if these riparian thickets do
expand,additional habitat for moose,songbirds,and furbearers may
be provided.
Disposal of materials excavated from the power tunnel and fish
passage facility will be stockpiled in the floodplain above the
dike,When the dike is completed and the lake level raised to an
elevation of 1155 ft,this disposal ar,,"',as well as portions of the
lakeshore will,be flooded ..In the area subjected to the annual
fluctuations of lake water levels,portions of the Nagishlamina,
Chilligan,and other smaller lake tributary deltas will most likely
realize a change in their vegetative cover..Vegetation Dlay recede
due to inundation and shoreline destabilization.However,such
changes are expected to influence only a small area since under
pre-project conditions,the lake level occasionally reaches
elevations at or near 1155 ft..Above the high water level,the
shore may also develop a different species composition;one more,
representative of e~rly seral .stages and wetter soil conditions ..
The anticipated changes in riparian and shoreline vegetation cannot
be further refined until site specific,field verified,habitat maps
have been prepared and the operating reservoir levels better defined.
4087A
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Downstream from the McArthur and Chakachatna canyons,the influence
of altered flows,either increased or decreased,on riparian
vegetation will depend upon the direction and magnitude of channel
migrations and the amount of floodplain urea removed from the
influence of flood events.Based upon'current information,the
McArthur River channel above Noaukta Slough has been naturally
migrating and some rechanneling has occurred in the slough under
norma.l flow contiitions.Sustained higher flows in the upp:er
McArthur River may result in accelerating this migration.The
extent of channel migration is also dependent upon floodplai.n
substrate on these parameters,the speed,directi.on,and magnitude
of migration in the upper McArthur River cannot be assessed.The
influence of reduced flows in the Chakachatna River and Noaukta
Slough may be to reduce the frequency and magnitude of rechanneling
in the slough and to remove portions of the now active floodplain
from the influence of flood events.Based upon current .information,
it is not possible at this time to estimate the location,extent,or
timing of revegetation.
The influence of wind or vehicle generated dust emanating f:t'om
cleared areas,roads,and borrow pits may influence the vegetative
community composition in the itnmediate vicinity of these facilties.
Accumulations of dust may accelerate the rate at which snow melts
and affect the growth of cottongrass and mosses.The extent of
vegetati.on changed due to accuDlulations of dust will be dependent
upon the methods and level of effort exerted to reduce dust.
0.££road use of vehicles in the project area may a.ffect vegetation
depending upon the type of vehicle,the time of year 1I and solI
moisture conditions.Currently,no policy exists to control or
permit off road use of the site.
4087A
B-73
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The construction and operation of the Chakachamna Lake Hydroelectric
project will also affect the wildlife resources of the.area.Direct
habitat losses due to facility siting will occur with construction
of the dike,disposal areas,powerhouse,fish passage facility,
camps,roads,airstrip,port and docking facilities,and borrow
pits.The influe"lce of this habitat loss on wildlife populations
should be negligible.The dike will be sited at the outlet of
Chakachamna Lake;an area that receives little use by birds and
mammalSe The powerhouse and fish passage facility will be located
in the McArthur River and Chakachatn~River canyons»respectively.
Because these facilities will be primarily underground,relatively
small quantities of surface habitat will be lost.Although the
exact size and precise location of the remaining facilities have not
been determined,each will occupy a relatively small amount of
habitat in an area that is not considered to be essential to any
species of bird or mammal.Development:of disposal areas in both
the McArthur and Chakachatna floodplains 'Will result in the largest
habitat loss,and greatest disturbance to birds and mammals.
Without proper site selection,stockpile design,and erosion
control,this disposal could significantly alter valuable riparian
habitats,and detrimentally affect wildlife species that rely upon
these habitats.Moose,ptarmigan,small mammals,and ~Jasserine
birds would be mos t likely affected from su'bstantial floodplain
habitat alterations.
B-74
In the vicinity of the lake above the dik~,fluctuating water levels
may have several implications_As the lake level is lowered during
the winter,ice along the shore will most likely fracture,
eventually resulting in a zone of broken ice that may prevent some
large mammals from ventur.ing out onto the frozen lakesurfa.ce.
Moose,bears,liolves,and small mammals are the primary inhabitants
of the lake shore during winter.However,the degree to which these
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4087,A
B-75
Below the canyons,wildlife activity is more abundant and diverse.
In thes2 areas)a variety of 'Wildlife species could be influenced by
construction activities.~~e to increased levels of noise and
disturbance,sensitive sp~~ies such·as moose,grizzly bears,gray
wolves ,eagles,(.i swe.l1smay discontinue their use of the affected
area.Other spet.ies,including coyotes,ducks,and other small
birds,are more tolerant of distu.rbance and will probably not alter
their distribution.If avoidance of a contruction area occurred it
liould most likely be temporary wi th individuals returning to the
area soon after noise and activi ty levels subsided.However,if
areas used by wildlife for important life functions are abandoned,a
decrease in the ab1.lndance of sotne loca.l species may be noted.'Xo
mammals use the frozen lake surfac.e will need to be established.
During tbe ice free period,a variety of birds and mammals use the
shore of the lake.The higher,fluctuating water level during this
period may al.ter small areas of shoreline habitat;but should not
significantly influence the overall USe of the shore by these
wildlife.
Construction activities occurring in the Chakachatna River and
McArthur River canyons may influence the apparently limited use of
the canyons by mammals and birds.The canyons are uSEd by eagles,
bears,furbearers,moose,and passerine bird~;,.Near the
construction sites,increased levels of noise from heavy e ..~uipment
and blasting ttlay discourage eagles ,moose,and bears from u$ing
adjacent areas.However,othe'['mammals~including furbearers and
small birds appear to have a hi,gher tolerance for human disturbance
and may not:substantially alter their distribution.This influence
of noise and disturbance on wildlife popolations in the canyons
should be limited to the consti:'uction period.
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eVs'luatewhich $peciesmay be affected and to what extent ,it will
be necessary to establish the use and importance of the Chakacha.tna
and McArthur floodplains to wildlife ..
The alteration of habitat and wildlife distributions below the
canyons during the operation of the project may be evldent 115 a
result of cha.ngesl in the vegetation communities or as changes in the
abundance or distribution of prey (particularly anadromol,ls fish).
Changes in the distribution of vegetation will probably not result
in significant changes in the distribution of wildlife populations.
Channel migration along the upper McArthur River and rechanneling in
Roaukta Slough may erode relatiVely small areas of riparian
vegetation.This may dispJ.,.ace a few individua.ls,but averall
abundance of a.wildlife population in the project area should net be
significantly changed.LikeWise,a small increase in the abundance
of floodplain riparian vegetation along the Chakachatna River will
probably not result in a significant change inlliildlif~species
diversity or abund~nce in this drainage.The anticipated changes
may be more clearly defined by acquiring information on the extent
of channel migration,revegf!tat:J.on,and the use of riparian areas
for denning,winte.ring,breeding,and calVing.
It is unlik.ely that minor changes i.n anadromous fi.sh abundance and
distribution will have a significant effect on the distribution of
ei ther birds or mamrn.sls.Several species of wildlife feed on
anadromous fish.Although bears a.nd eagles are the most Visible,
m.ink,harbor seals,and beluga whales also consume fish originating
in the Chakachatna or McArthur jrainages.The degree to which these
species will be affectecl can be evaluated by investigating the
anticipated changes in fish distribution or abundance and the
reliance of wildlife on this resources.Based upon.the anticipated
change in anadromous fish abundance and the opportunistic nature of
4087A
B.....76
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the wildlife species involved,no significant change in the
abundance of distribution of wildlife is currently expected to occur
in either the Chakachatna or McArthur drainage as a result of this
project.
Increased access to the area tiil!affect wildlife populations by two
means;increased disturbance from eonstruct.ion activities,and
increased local hunting (sport and subsistence)pressure..By
utilizing the existing road network for constructi.on and operation
in the Chakachatna drainage,only a slight increase in vehicle
related disturbance to wildlife should occur.However,through the
construction and use of two road extensions to access the McArthur
drainage and Chakacha tna canyons,there will likely be a short term
reduction in the use of areas adjacent to these roads by species
that are sensitive to traffic,particularly moose,bears,wolves,
eagles,and swans.The extent of this influence will depend upon
the location of moose wintering and calving grounds,the location of
brown bear,black bear,wolf,and wolverine denning sites,and the
location of swan and eagle nesting,brood rearing,andfa1!staging
areas.Fu.ture studies will be needed to identify the locations of
these important habitatG and to allow for more defi"..titre
assessments.
Whether local wildlife populations are influenced by increased
hunting pressure will depend upon the magnitude·of the hunting
increase and the level of road accessallQwed.Currently no policy
affecting access of the project area has been outlined.
The influence on wildlife of constructing and maintaining a
transmission line and the likelihood of bird collisions or
electrocutions with the lines tiill be dependent upon the species
inhabiting the area,transmission line design,and construction and
4087A
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B"'78
maintenance techniques.Until this informati.on is available,these
effects cannot be measured.
4087A
This project will also create impacts due to improved access and the
potential for increased recreational activities (eag.,hiking,
fishing,hunting).Tne extent of this impact is unknown at this
time,but is likely to be secondary to the boom/bust constJ;uction
activities.
The socioeconomic impacts of th~proposed Chakachamna Hydroelectric
development are signifIcant.The construction and operation of a.
large hydroelectric plant has a high potential to cause a boom/bust
cycle,causing significant impact on community infrastructure..The
site is located at or near communities with a popula.tion of less
than 500.An inmigration of apprQximately 250 workers will be
necessary for construction.In some of these '!'emote communities,
the population would more than quadruple.The installation of a
construction camp would not mitigate the impacts on the social and
economic structure of a community.
The expenditures that flow out of the region account for investment
in equipment and supervisory personnel.For this large scale
project.,a larger proportion of the expenditures can·be a.ttributed
to the civil costs.Approximately 35 percent of an investment in
the project will be made outside the region while 65 percent will be
made within Alaska.The breakdown of operating and maintenance
expenditures for a hydroelectric pr(":0ct will be approximately 11
percent spent outside the state and 89 percent spent wi thin the
regie!':-
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B-T9
4.6 AESTHETICFAC'IORS
The potential &esthetic impacts of the proposed Cbakachamna
Hydroelectric.development are significant,particularly from a
visual standpoint..F~tential fluctuations in Lake Chakachamna
levels will leave exposed lakeshore (bottom)at certain periods ..
Significant reduction in outflows will result in the loss of much of
the white water reach of the Chakachatna River canyon,as well as
noticeable alterations to the floodplain.Disposal areas in
McArthur valley will be noticeable,and together will support
facilities (roads,powerhouse,etc.)will result in degradation of
the aesthetic character of pristine wilderness landscapes.
4087A
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It 1s apparent that there is no one superior project alternative in
terms of minimizing environmental impacts in all categories.
Rather,many impacts are a function of specific site selection,
detailed engineering and extent of mitigative measures.Compliance
with regulatory criteria and good engineering practices should
minimize most impacts.To further differentiate between
alternatives from an environIllental standpoint would require
weighting of factors between categories,an involved process which
requires input from all parties who have an intereJt in or who may
be affected by project development.
The environmental and socioeconomic effec ts of the above described
development scenarios are substantial and extremely varied.Table
B-4 presents a summary of'SODle of the environment-relat~d 'facility
characterist,fes of thesealt:ernatives.Based upon these data,
together with the detailed discussions presented in the ind:l.vidual
environmental sections,relative environmental impacts by category
for If}cationand technology options are summarized in Table B-5"
5.0 SUMMARY AND CO NCLUSIO NS
The ra.nking value,S within an individual category are unweighted with
respect to another category.For example,a moderate impact to
water resources may be more significant than a high impact to
aesthetics ..
4094A
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1.64.UUon
(ave)
1.64 .UUon
(ave)
Chakachallna
(Hydro)
1,220
1-2
~
40
70
15
25
soo-aoo
200
120-175
200
130-150
c::::::J'
Beluga
(Nat.Gas)
c::::J
40
70
15
25
500-aoo
200
120-17.5
200
130-150
","lrtrt'-"*·'-lffi~iI-.•-i~'···~i~·,~~:"'--·II;.i~_··',-',-',/,.~,..,..."-.'to .....~~.~._--....-........~.'....'.'''.....,,'
L::J ·k::J
100-20l0
200
90-140
5
100-200
50-1~0
Locati~n/Tech~ol~gy
Fairbanks Kenai
(Nat.Gas)(Nat.Gas)
t.o._~iiC:....J
2.5-50
50
60-90!:./
5
115-200
140-200
;~~~~~"",--~~~./~""~~-:"""''''''l''''lW·t.,~~..,*"'t>.,"~1!""*",,,*_.,.........'it:'h#••'
North Slope
(Nat.Gas)
t:::::31J
TABLE B-4
287d1
r;:,~...J
None
Infrequent
Nenana
(Coal Flred)
1i.,~2
•~'...po
."~..-•..,--r~--,.','-\"~~J'~::::,<"~"'~".>
............
287d l
None
Infrequent
i'_-....:J
25 25--
50 50
500 500
109 109
0.03 O.OJ al al al a/NegligibleO.@/0.06b;al al al a/
0.6 0.6 cl cl cl cl
50 50 50 50
Beluga
(Coal Fll'ed)
(,.J
EHVIRONHENTRELATED FACILITY CHARACTERISTICS FOR ALTERNATIVE POWER GENERATION OPTIONS
L ..J
(lb/106 JJtu)
(lb/106 Btu)
(lb/l06 8UI)
l '=-_-..1
'.,......__.8,,5 . -
b ~~~---'.-~_.~._~.~,...."""-~~'~~"";""-'-"'---"._J;,:.,.;""~.,.,."",.,"';'-"',,,,"",,~'*,..;..;,.,...."'-'-_..{\;".""""".'""'~.~......
r-.r_
Environllental
Factor
Air Environllent
bisB10ns
Particulate Hatter
Sulfur Dioxide
Nitrogen Oxides
~lant DIscharge Requirements (gpm)
Process Water
Coal Pile Runoff
nemlnera!izer
Stream Generators
treated Sanitary Waste
lloor Drains
Water Enviro~ent
Plant Wa.terRequlrellents (gpla)
Water Injection
Other
Physical Effects-(lIax.struct.height ft.)
Land Envrronllent
Land Require~ent8 (acres)
Plant
Construction Camp
SOlid Naste Disposal
Socioeconomic Environllent
Construction I{orkfol:ce,peak (peroolln.d)
OperatfngWorkfol'ce (personnel)
4094A
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a/!elow standards
bl Assumes 70%Reduction
eJ E.la81.on8 variable within standards.Dry control techniques would be used to meet calculated Noxstandard of 0.OI4pel:cent of
totalvolulle ofgsseous ellissions.This vsl:ue calculated based upon new source performance standards,faci1!ty heat rate and unit
size.
d/Dry Cooling.We,t Cooling •1,941 gpm
el In~ludes Switchyard
".
#
J
~iPi·~$h..~1!l,'..w~~¢"5ittttIA'~et'*it'¥":A"<'~"$'""'''*J'i"}'"ViE"6"'t~-
i:;r:-,";':",\--,-=~W,••'C!@.$¥;l(i;l"'I."'-1_""'·"''''''',~---~-~......-~
'>i;,"<'.,.~,'."~"'1",'"~0
la.ha-it"l oiJi,t
I I
<,---,,,::,
~
-
......
..
-
..
8'-;1
Chakachaana
(Hydto)
..
~
..
Beluga
(Nat.Gas)
.r:::=:J
..
1_._1
IaI
':c=I
m.1I
"
.£:::J
!til
E=:Jl
'I!JI
TABLE 1-5
Location/Technology
North Slope Fairban~sIKe-naTltf1klski
(Nat.Gas)(Nat.Gao)(Nat~,-CIllS)
L J
laD
"".."...,,·-,··,~\ll_·;;il'!Oi'.~;;~4~-_;J!lii!~~tt~~"""_''''f .....r.......,iL....1I!W'r~J1"lt S.VI._J)i!\1tMLU""fjn
I!'
Nenana
(Coal FIred
C"'1
IE~
2 4 2 J 1 1 0
J 1 1.2 0.2 0,2 2 4
0 0 1,2 0,2 11\2 0 4
2 2 1,3 0,3 0.3 1 2
4 1 1.2 1~.2 I n 2 3 3
3 2
.
1.4 1.3 1.3 2 3
lIeluga
(Coal Fired)
L l
IE
lPALITATIVE RANKING OFENV.IRONHENTALDJPACTS ASSOCIATED WITH ALTERNATIVE PROJECTS
L-:::J
-
L-.-J
"-----:;c----~------;;;::--."':'0-----8.5 ------~--.~~-.----,---,-=-~~,-~~c_:-:-..~"=-
Aes.the ti·\:S
Vater Re~ources
Aqua ticEcolog)"
Environaental
Category
Key:0 -no i.paet
1 -lOll impact
2 -.oderate i.pact
3-high Impact
4-severe impact
Terrestrial Ecology
Socioeconomics
Airllesources
.NOTE:In cases where two ItUllbers appear.thefirstnWllber teferti to the power plant only,whUe ~he .econd number
incorporates8econdary support facility f.PllCts (eog ••888 line.tJ:'anaalss1on line).
--~--------------------------------------------
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6.0 REFERENCES
Alaska Power Authority.1983a.Befo:t'~the Federal Energy Regulatory
Commission ~pplication for license for major project -Susitna
Hydroelectric Project.Volume 1 -Initial Statement.Exhibit A,
C.D.Alaska POlier Authority..Anchorage,Alaska..
Alaska Power Authority.1983b.Use of North Slope gas for heat and
electricity in.the Railbelt -final report.Ebasco SerVices,
Inc.Bellevue,Washington.
Bonneville Power Administration.1981.Underground cable systems:
Potential environmental impacts,Draft Report.Bonneville Power
Administration,Washington,D.C.
Bureau of land Management.1980.The utiliy'cqrridor,land use
decisions.U.S.Department of the Interior,Burea.u of Land
Management,Fairbanks,Alaska.
Commonwealth Associates,Inc.1982.Environmental Assessment Rep",\rt
for the Anchorage-Fairbanks Transmission Intertie.Alaska Power
Authority,Anchorage,Alaska.
Dvorak,A.J.1978.Impactr.-of coal-fired plants on fish,Wildlife,
and their habitats.Argonne National Laborator,Office of
Biological Services and Environm~1tal Contaminants Evaluation of
the Fish and Wildlife Service.U.S.Dept..of the Interior.
Argonne,Ill.
Ebasco SerVices Incorporated It 1981a.Railbelt electric power
alternatives study,technology aSsessment p1;'ofile report.
Ebasco SerVices Inc.BelleVue,Washington.
I
I
!r
I
I
I
o
~..
I
I
I
4095A
B-S3
1 .....;,:...",
o
I
~
'g
D
C
C
o
D
C 0
a I
o I
o
o f]I
~D
,.1
J
I
J
Water and wastewater
generating s.tations.
Conference.Illinois
Alaska regional proflleG:Vol.1,Southcentral
Yukon region.Arctic Environmental Information
University of Alaska.Anchotage,Alaska.
B-84
Ebasco Services Incorporated.1981c.Railbelt e1ec.trie power
alternatives study.natural gas combined cycle alternative.
Ebasco Services Inc..Bellevue,Wa'shington
Ebaseo Services;Ineorporatedfl 1981b.Railbelt electric power
alternatives study,coal fired steam electri.c alternative.,
Ebasco Services Inc..Bellevue,WashingtOT;,.o
Kim,K.Bo J E.F.Dul,and J.N.Brogard..1975.
management at fossil fueled power
Proceedings .of the Ameri can Power
Institute of Technology.Chicago,lll.
£basco Servic~s Incorpo:t'a,ted.1982.Railbe1t electric power
alternatives study J Chakachamna Hydroelectric alternative.
Ebasco Services Inc.Bel1e'\'Ue,Washington.
Leopold,A.and F.Darling.1953.Effects of land use on moose and
caribou in Alaska.Transactions of the North American Wildlife
Conference.18:553-582.
Nelson.GoR.1974.Water recycle/reuse possibilities:power plant
boiler and cooling systems.U.S.EnviI'onmentalProtection
Agency.Pacific Northwest Environmental Research Labora.tory ..
Corvalis,Oregon.
North Slope Borough.1978.Coastal management program,Prudhoe Bay
Area~North Slope Borough,Barrow,Alaska.
Selkregg,L.1974.
regicm,Vol.2,
and Data Center,
4095A
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i
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I
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~.'...
•Ii.~
II
I
f
I
1 I
1
I
I
I
I
I
1 I
,...I.:1.1.I i .~
!OJ
""1 ItoI..
}
University of Alaska,Arctic Envit'onmenta1 Information and Data
i
Sou thereentral
B....S5
J,----~
,...~
Alaska Regional.Profilas,1974.
State of Alaska~Office of the Governor,Juneau,Ala.ska ..
Center.
Region.
4095A
Spencer,D.L.,and E.F.Chatelain.1953..Progress in the manageIIlent
of the moose of South Central Alaska.Transactions of the Notth
American Wildlife Conference.18:539-552.
0'1
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