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REPORT No.2
I AL REPORT
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OCTOB R 1885
DO OMENT No.2822
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Document No.2922
Susitna File No.4.3.1.9
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SUSITNA HYDROELECTRIC PROJECT
IMPOUNDMENT AREA FISH IMPACT ASSESSMENT
AND MITIGATION PLAN
Impact ~ssessment and Mitigation
Report No.2
Report by
Entrix,Inc .
Under Contract to
Harza-Ebasco Susitna Joint Venture
Prepared for
Alaska Power Authority
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Final Report
October 19.85
A.RLIS
.Alaska Resources
LIbrary &Information ServlCes
Anchorage,Alaska
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NOTICE
ANY QUESTIONS OR COMMENTS CONCERNING
THIS REPORT SHOULD BE DIRECTED TO
THE ALASKA POWER AUTHORITY
SUSITNA PROJECT OFFICE
ARLJS
.Alaska R 'Llbnuy &.esources
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Preface
Th is report represents one volume of a four volume report seri es on aquat ic
impact assessment,mitigation planning and monitoring for the proposed Susitna
Hydroelectric Project.These volumes are:
1.Access Corridor,Construction Zone,and Transmission Corridor Fish Impact
Assessment and Mitigation Plan
2.Impoundment Area Fish Impact Assessment and Mitigation Plan
3.Downstream Fish Impact Assessment and Mitigation Plan
4.Aquatic Monitoring Plan
Impact assessments in these reports have focused on anticipated project impacts·
on selected evaluation species.Project evaluation species were chosen based on
their sensitivity to change,abundance .in affected habitats and human use
values.
A primary goal of the Alaska Power Authority's mitigation policy is to maintain
the productivity of natural reproducing populations,where possible.Mitigation
planning follows procedures set forth in the Alaska Power Authority Mitigation
Policy for the Susitna Hydroelectric Project (APA 1982),which is based on the.
U.S.Fish and Wildlife Service and Alaska Department of Fish and Game mitigation
policies (USFWS 1981,ADF&G 1982a).Mitigation planning is a continuing
process,which evolves with advances in the design of the project,increased
understanding of fish populations and habitats in the basin and analyses of.
potential impacts.An important element of this evolution is frequent
consultation with the public and regulatory agencies to evaluate the adequacy of
the planning process.Aquatic mitigation planning began during preparation of
the Susitna Hydroelectric Project Feasibility Report (Acres American,Inc.1982)
and was further developed in the FERC License Application (APA 1983a,1983b).A
detailed presentation of potential mitigation measures to mitigate impacts to
chum salmon that spawn in side sloughs was prepared in November 1984 (WCC 1984).
i i
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TABLE OF CONTENTS
PREFACE
LIST OF FIGURES
LIST OF TABLES.
SUMMARY . . . . .
1.0 INTRODUCTION
i i
v
vi
viii
1
2.0 PROJECT DESCRIPTION AND OPERATION.
2.1 Stage 1 ~Watana Reservoir ..
2.2 Stage II -Devil Canyon Reservoir
2.3 Stage III -Watana Reservoir .••
2
2
3
3
,~3.0 FISH RESOURCES IN THE IMPOUNDMENT ZONES.·5
3.1 Arctic Grayling ·· · ·
·· · ···5
3.2 Burbot.. . .· ··· · ·
.· ··9
F""
3.3 Dolly Varden.········ ·
9
3.4 Longnose Sucker ·.· · ·
.-.· ··11
~3.5 Round Whitefish 11·.· · · · · · ··· · ·
. .
3.6 Humpback Whitefish.·. .··12
3.7 Lake Trout..· · · · · ·
·· · ·
. .12
3.8 Slimy Sculpin ···· · ·
12
3.9 Chinook Salmon.··. .· · ····· ·
12
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iii
TABLE OF CONTENTS (Continued)
Page
4.0 ANTICIPATED IMPACTS.·· ·
··.·· ·· ··14
4.1 Stage I -Watana Reservoir.·14
"""'-4.1.1 Inundation ·..· · · · · ···14
4.1.2 Drawdown ·· · · ·
14
""'"4.1.3 Water Quality.16,··· ··
4.1.4 Effects on Fish.··· ······20
4.2 Stage II -Devil Canyon Reservoir ··· · · · · · · · · ·
27
4.2.1 Inundation · · · · · ··27
4.2.2 Drawdown · · · · ·
29
4.2.3 Water Quality.·· · ··29
4.2.4 Effects on Fish.··· · ·
33
,;,?!,~4.3 Stage III -Watana Reservoir.38······ · · ·
4.3.1 Inundation · ·
·····38
4.3.2 Drawdown ··· ·· ···38
4.3.3 Water Quality.····· · · · ·····42.-4.3.4 Effects on Fish.·.··42
5.0 SELECTION OF EVALUATION SPECIES.·· ·· ········ ·
46
6.0 DEVELOPMENT OF MITIGATION PLAN .
6.1 Approach to Mitigation .
6.2 History of Impoundment Mitigation Planning ..
6.3 Mitigation Options .
6.3.1 Acquisition of Public Access .
6.3.2 Habitat Improvements .
6.3.3 Hatchery Propagation of Arctic Grayling ..
48
48
51
• • • •54
54
59
61
7.0 LITERATURE CITED 64
iv
Figure 4.Stage III Watana water surface elevation monthly summary.
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Figure 1.
Figure 2.
Figure 3.
Figure 5.
Figure 6.
Figure 7.
LIST OF FIGURES
Stage I Watana water surface elevation monthly summary.
St~ge II Devil Canyon water surface elevation monthly
summary with Stage I Watana operati ng . . . . . . . . .
Stage I Watana water surface elevation monthly summary
with Stage .I I Devil Canyon operating.. . . . . . . . .
Stage II Devil Canyon water surface elevation monthly
summary with Stage III Watana operating ...•
Mitigation plan development and implementation.
Option Analysis .
v
17
30
31
40
41
49
50
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Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
LIST OF TABLES
Common and scientific names of fish species observed
in the Watana and Devil Canyon impoundment zones
Arctic grayling population estimates in selected
tributaries of the Watana impoundment zone ...
Arctic grayling population estimates in selected
tributaries of the Devil Canyon impoundment zone
Burbot total catch and catch rates in the Watana
impoundment zone,1982 • • • •••
Topographical features of selected tributaries within
the proposed Stage I Watana impoundment.• . . . . . .
Summary of selected species relative abundance,sport value
and sensitivity to habitat alteration in tributary habitats
of the proposed Stage I Watana impoundment zone ..•....
Summary of selected species relative abundance,sport value
and sensitivity to habitat alteration in mainstem habitats
of the proposed Stage I Watana impoundment zone.. . .
Topographical features of selected tributaries within
the proposed Devil Canyon impoundment •...•...•
Summary of selected species relative abundance,sport value
and sensitivity to habitat alteration in tributary habitats
of the proposed Devil Canyon impoundment zone •.......
vi
6
7
8
10
15
23
26
28
35
Table 10.
LIST OF TABLES (Continued)
Summary of of selected species relative abundance,sport value
and sensitivity to habitat alteration in mainstem habitats
of the proposed Devil Canyon impoundment zone.. • . . . . . . .37
Table 11.Topographical features of selected tributaries within
the proposed Stage III Watana impoundment ....•... .39
Table 12.Summary of selected species relative abundance,sport value
and sensitivity to habitat alteration in lake habitats of the
proposed Stage I II Watana impoundment zone . ........44
Table 13.Agency comments on Impoundment Mitigation Planning 53
Table 14.Land acquisitions and facilities development projects
currently proposed by the State of Alaska in the Susitna
R-i ver Bas in.. . . . . . .IIlI •II • •..Co •e •011 •co • •56
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Table 15.Proposed fisheries mitigation for the impoundment zone with
estimated capital and annual operating costs ... . . . . .58
vii
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Summary
This report presents analyses of anticipated impacts and mitigation measures
that can be used to develop an acceptable fish mitigation plan in the
impoundment zone of the proposed Susitna Hydroelectric Project.In the
impoundment zone,the Arctic grayling is the primary evaluation species.
Impact analyses indicate that Arctic grayling spawning,incubating and rearing
habitats will be adversely affected by the proposed impoundments.
Approximately 26 miles of the larger tributaries,which provide important
spawning,incubating and rearing habitat for approximately 20,000 grayl ing,
will be inundated by the three-stage project.Most of the grayling inhabiting
inundated reaches are expected to be displaced and lost.This impact is
considered unavoidable.
To compensate for impoundment zone impacts,the acquisition of public access
to the Susitna River and its tributaries below Devil Canyon and habitat
improvements to enhance important resident or sport species of salmon in the
middle Susitna River are the primary mitigation options proposed.The capital
costs of the primary mitigation features are expected to cost about $940,000.
Annual operating and maintenance costs are anticipated to be about $20,000.
The expansion of an Arctic grayling hatchery to stock grayling in within-basin
and out-of-basin areas is the least preferred of the mitigation options
presented.
viii
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1.0 INTRODUCTION
This report presents analyses of anticipated impacts and mitigation measures
that can be used in developing an acceptable fish mitigation plan in the
impoundment zones of the proposed Susitna Hydroelectric Project.Compensation
is the highest mitigation option achievable for impacts in the impoundment
zones.Higher priority options,such as avoidance,minimization,rectifica-
tion and reduction,are considered infeasible (APA 1983b,APA 1985d).
Three measures for providing compensation for the expected losses of fish
habitats and fishery resources in the impoundment zones are evaluated in this
report.Based on input from resource agencies,acquiring public access to the
Susitna River and its tributaries below Devil Canyon and habitat modifications
or improvements in the middle Susitna River (between Devil Canyon and
Talkeetna)that would enhance important resident species (rainbow trout or
Arctic grayling)or important sport species of salmon (chinook or coho salmon)
are preferred compensation measures (ADF&G 1984).The least preferred
compensat i on measure evaluated is the hatchery propagation and stocki ng of
Arctic grayling.Final decisions on the strategy to be implemented will be
made through negotiations between the Power Authority and resource managers .
1
~~2.0 PROJECT DESCRIPTION AND OPERATION
In May 1985,the Power Authority decided that the Susitna Hydroelectric
Project would be a two-dam,three-stage development (APA 1985a).Under this
approach,a 705 ft high materi a l-fill dam wi 11 be bu il t duri ng Stage I
development at Watana (RM 184).Stage II includes the construction of a
646 ft concrete-arch dam,with a material-fill saddle dam at Devil Canyon
(RM 152).Stage II I development will rai se the Stage I Watana dam 180 ft to a
crest height of 885 ft.Completion of the three-stage development will result
'in a two-dam system similar to that described in the original FERC license
application (APA 1983a,b).
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Under the present schedule,construction of diversion tunnels and cofferdams
for the Stage I Watana development 'will begin in 1992,with all turbines
on -1i ne for power production by 1999.The Stage II development wi 11 beg in at
Devil Canyon in 1995 and be comp1 eted by 2005.Stage II I construct i on wi 11
commence in 2006 and be finished in 2012 (APA 1985e).
2.1 STAGE I -WATANA RESERVOIR
The Stage I development of the Watana dam (RM 184)will impound a reservoir of
approximately 4.3 million acre-feet,with a surface area of 20,000 acres (APA
1985b).The normal maximum water surface elevation (WSE)will be 2000 ft
above mean sea 1 eve1 (MSL),whil e the normal minimum water 1 evel wi 11 be
elevation (el.)1850.At el.2000,the maximum reservoir depth will be 550
ft,while the mean depth is expected to be about 200 ft.
The Stage I Watana reservoir will be operated in the store-and-release mode.
Under average climatic conditions,the reservoir will be filled to el.2000 by
late August or early September.To meet power production needs,the reservoir
will be drawn down from October through April.The maximum drawdown will be
150 ft and wi 11 proceed at an average rate of 0.7 ft per day.The mi nimum
drawdown level at e1.1850 will usually occur in late April or early May.The
reservoir will be refilled during the summer (May through August)when
tri butary runoff and gl acial meltwater are high.During years of normal
2
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climatic conditions,refilling will increase the WSE 1.3 ft per day (APA
1985d).
2.2 STAGE II -DEVIL CANYON RESERVOIR
When the Devil Canyon dam (RM 152)is completed,the Stage I Watana dam will
be used primarily for power-peaking and reserve energy product ion,whil e the
Devil Canyon dam will be operated to meet base10ad energy demands.The Devil
Canyon reservoir will optimize power production at a normal maximum WSE of
1455 above MSL from November through July (APA 1985b).Drawdown will occur
during 1ate July,August and early September duri ng average or dry years to
meet power production needs and downstream flow re1 eases whil e the Watana
reservoi r is refi 11 i ng.The normal maxi mum drawdown wi 11 be 50 ft,to e.1.
1405,wi th refi 11 i ng occurri ng duri ng 1ate September and October.In wet
years,there will be no need to drawdown the Devil Canyon reservoir (APA
1985d).
At the normal operating water level of 1455 ft,the Devil Canyon reservoir
will have a volume of 1.1 million acre-feet and a surface area of 7,800 acres.
The reservo i r's maxi mum depth wi 11 be 580 ft,wh i1 e the mean depth wi 11 be
140 ft (APA 1985b).
2.3 STAGE III -WATANA RESERVOIR
The Stage III development of the Susitna Hydroelectric Project will raise the
pool of the Watana reservoir 185 ft.The total volume of the Stage III Watana
reservoir will be approximately 9.5 million acre-feet,with a total surface
area of 38,000 acres (APA 1985b).The normal maximum WSE of the reservoir
will be el.2185,while the normal minimum water level is expected to be e1.
2065.At e1.2185,the maximum reservoir depth will be 735 ft.
The Stage III Watana reservoir will operate in the store-and-re1ease mode (APA
1985b).The drawdown and refill cycle will follow a pattern similar to that
of the Stage I reservoi r drawdown.Under average c1 imat ic condi t ions the
reservoi r will be fi 11 ed to e1.2185 by 1ate August or earl y September.
Drawdown wi 11 occur from October through April,with refi 11 i ng taking place
3
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from May through August.The maximum drawdown wi 11 be approximately 120 ft
r and will occur at an average rate of 0.5 ft per day.Refilling will increase
the water level in the reservoir an average of 1.0 ft per day (APA 1985d).
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The drawdown and refi 11 i ng cycle of the Stage II Devi 1 Canyon reservo ir wi th
Stage III Watana in place is expected to be similar to that of the Devil
Canyon reservoir with Stage I Watana operating.The magnitude,timing and
duration of the drawdown and refill ing cycle of the Stage II Devil Canyon
reservoir was described in Section 2.2.
4
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:LO FISH RESOURCES IN THE IMPOUNDMENT ZONES
Nine species of fish have been observed in the impoundment zone (Table 1).A
brief summary of life history information and distribution and abundance data
of the fish species observed in the impoundment area is presented in the
following sections (3.1 through 3.9).
3.1.ARCTIC GRAYLING
Arct ic grayl i ng are abundant throughout the upper Sus i tna Ri ver bas in and are
Irlidely distributed in tributary habitats during the summer (ADF&G 1981a,
1983a).During the fall,it is suspected that most fish move into the Susitna
River mainstem to overwinter,except in tributaries that have fish passage
barriers (e.g.Deadman Creek).Fish residing upstream of the waterfall s in
Deadman Creek likely move into Deadman Lake or may,less commonly,overwinter
'in deeper pool s of Deadman Creek (Sautner and Stratton 1984).
Arctic grayling move from the mainstem back into tributaries to spawn in the
spring (late April and May).Spent fish were captured in tributaries
'immediately after spring breakup (ADF&G 1983a).Depending upon the actual
timing of spawning,incubation extends from May into June (Morrow 1980).
Adul t grayl i ng rear in tri butari es throughout the summer.Juveni 1e grayl i ng
rear in natal tributaries,clearwater sloughs and in the mainstem near
tributary mouths.
The size of Arctic grayling populations has been estimated in the reaches of
the larger tributaries in the impoundment zones (Tables 2 and 3).Based on
mark and recapture estimates in 1981 and 1982,over 16,300 Arctic grayling
(greater than 150 mm in length)reside during summer in tributary reaches that
will be inundated (ADF&G 1983a).Arctic grayling also occur in Sally Lake,
which will be inundated by the Stage III Watana reservoir.In 1982 attempts
were made to estimate the population size of grayling in Sally Lake.However,
due to few recaptures of tagged fish,an estimate based on mark and recapture
was not made.It is believed that the population size of Arctic grayling in
Sally Lake is in the vicinity of 5,000 fish (ADF&G 1983a).
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Table 1.Common and scientific names of fish species observed in the Watana
and Devil Canyon impoundment zones.
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Scientific Name
Salmonidae
Coregonus pidschian
Oncorhynchus tshawytscha
Prosopium cylindraceum
Salvelinus malma
Salvelinus namaycush
Thymallus arcticus
Catostomidae
Catostomus catostomus
Gadidae
Lata lata
Cottidae
Cottus cognatus
Common Name
humpback whitefish
chinook salmon
round whitefish
Dolly Varden
1ake trout
Arctic grayling
longnose sucker
burbot
slimy sculpin
-c'
Source:ADF&G 1981a,1983a;Sautner and Stratton 1984.
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Table 2.Arctic grayling population estimates in selected tributaries of the Watana
impoundment zone.
Tributary
River
Mile
Estimated
Grayling 1
per Mile
Estimated TributazY
Miles Inundated
stage I stage III Total
Estimated Number of
Grayling in Inundated Reach
stage I stage III Total
Total
Deadman Creek
Watana Creek
~Rosina Creek
Jay Creek
Goose Creek
Oshetna River
186.7
194.1
206.8
208.5
231.3
233.4
1,835 3
324
1,232
455
791
1,103
2.0
7.5
2.8
2.1
0.0
-.Jh.Q
14.4
0.7
4.3
1.7
1.4
1.2
~
11.5
2.7
11.8
4.5
3.5
1.2
2.2
25.9
3,670
2,.30
3,450
995
o
o
10,505
1,285
1,393
2,094
637
949
2.427
8,785
4,955
3,823
5,544
1,592
949
2,427
19,290
1 Modified from ADF&G 1983a and APA 1985d.
2 Assumes reservoir at normal maximum operating level:stage I Watana =el.2000,
stage III Watana =el.2185.
3 Estimated grayling per mile in Deadman Creek was calculated by ADF&G (1983)for the reach
of stream below the falls (0.3 mi).Extrapolation of grayling per mile to total length
of stream inundated is likely an overestimation of grayling population size.
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Table 3.Arctic grayling population estimates in selected tributaries of the
Devil Canyon impoundment zone.
{~Estimated Tributtry Estimated No.of Grayling
Tributary River Mile Miles Inundated in Inundated Reach
-Fog Creek 176.7 1.3 176
Tsusena Creek 181.3 0.4 1,000
Total 1.7 1,176
1 Assumes normal maximum reservoir level =el.1455.
~2 Source:ADF&G 1983a.
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3.2 BURBOT
Burbot are found in mainstem-influenced habitats of the upper Susitna River.
To date,they have not been captured in tri butari es or 1akes that wi 11 be
inundated.Burbot are relatively sedentary throughout the year,except during
the winter when they move to spawning areas (ADF&G 1983b,Morrow 1980).
~
Studies by ADF&G in the middle and lower reaches of the Susitna River indicate
that burbot spawn between January and March under the ice in the ma i nstem,
tributary mouths,slough mouths and in some of the larger tributaries (e.g.
Deshka River)(AOF&G 1983b).It is assumed that burbot in the upper Susitna
,~River exhibit similar reproductive timing and choice of habitat types.
During 1982,trotl ineswere set for burbot at six mainstem and one tributary
mouth sites in the Watana impoundment zone (ADF&G 1983a).Of the 135 burbot
captured,55 fish were caught in the Watana Creek mouth (RM 194.1),while the
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remaining fish were captured in the six mainstem sites (Table 4).
An attempt was made to estimate the population size of burbot within the
impoundment zones by the mark and recapture method in 1982.However,few
,-tagged fi sh were recaptured duri ng the study and an est i mate was not made
(ADF&G 1983a).
3.3 DOllY VARDEN
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Dolly Varden are found in some tributaries of the upper Susitna River basin
during the summer (ADF&G 1983a).Apparently,they are the dwarf
stream-resident variety described by Morrow (1980)and are rarely sought by
sport fishermen.
In 1981 one Dolly Varden was captured in Fog Creek,while in 1982 16 fish were
caught in Cheechako,Devi 1,Watana,Jay and upper Deadman creeks.The total
lengths of the captured fish ranged from 120 to 235 mm (ADF&G 1981a,1983a).
No population estimate of Dolly Varden in tributaries of the impoundment zones
has been done.Few fish (17 total)were caught during two years of extensive
9
-Table 4.Burbot total catch and catch rates in the Watana impoundment zone,
1982.
Mainstem River Catch (Catch Rate)
Site Mile May June July August Sept.Total
1 189.0 --(--)--(--)3(0.8)6(1.5) 7(1.8)16(1.3)
2 191.5 --(--)--(--)3(0.8)1(0.3)0(0.0)4(0.3)
3 197.8 --(--)8(2.0)3(0.8)--(--)--(--)11(1.4),.....
3A 201.6 --(--)--(--)--(--)6(1.5)7(1.8)13(1.6)
~4 201.2 --(--)5(1.3 )10(2.5)7(1.8)2(0.5)24(1.5)
5 208.1 --(--)4(1.0)2(0.5)4(1.0)2(0.5)12(0.8)
Watana 194.1 7(3.5)17(0.6)9(0.3)13(0.4)9(0.4)55(0.5)
Cr.Mouth
Total 7(3.5)34(0.8)30(0.6) 37(0.7)27(0.6)135(0.7)
Catch =number of burbot.
Catch Rate =Catch per trotline day.
--=No survey
Source:ADF&G 1983a.
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field reconnaissance and sampling effort (ADF&G 1981a,1983a).This suggests
that few Dolly Varden occur in the impoundment lones.
Although field data are not available to confirm the life history and habitat
requirements of Dolly Varden in the upper Susitna River,it is suspected that
they are similar to those described by ADF&G in the middle Susitna River
(ADF&G 1983b)and by Morrow (1980).It is likely that Dolly Varden spawn in
tri butari es in October and Novemb.er,wi th i ncubat ion occurri ng unt il March or
April.Rearing 1ikely occurs in tributaries,while overwintering may take
place in the deeper pools of tri butari es or in the rna i nstem of the Sus itna
River.
:3.4 lONGNOSE SUCKER
longnose sucker were captured in the upper Susitna River in the mainstem near
tributary mouths in 1981 and 1982 (ADF&G 1981a,1983a).Of the 210 adult fish
caught,197 were captured near tributary mouths.Watana Creek mouth produced
the highest catches of longnose sucker in 1981 and 1982,with over half of the
total catch occurring at this site.
It is suspected by ADF&G that longnose sucker spawn in tributaries in May and
June (ADF&G 1983b).Juvenile fish likely rear in tributaries,sloughs of the
mainstem and in the mainstem,while adults rear near tributary mouth habitats.
Overwintering likely occurs in the mainstem of the Susitna River.
3.5 ROUND WHITEFISH
In 1981 and 1982,38 adult round whitefish were captured in the mainstem near
tributary mouths in the upper Susitna River (ADF&G 1981a,1983a).Due to low
catches,life history information and habitat requirements for this species in
the upper Susitna River are limited.It is expected that the life history and
habitat requirements of rQund whitefish in this reach of the Susitna River are
similar to those described by ADF&G in the middle Susitna River (ADF&G 1983b)
and by Morrow (1980).Fish likely spawn in tributaries and mainstem areas in
October,while rearing occurs in the mainstem and near tributary and slough
mouths.Overwintering probably occurs in the mainstem.
11
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3.6 HUMPBACK WHITEFISH
Two humpback whitefish were caught in the upper Susitna River during 1981 and
1982 {ADF&G 1981a,1983a}.In 1981 one fish was captured near the mouth of
Kosina Creek,while in 1982 a single fish was caught at RM 208.1 in the
mainstem of the Susitna River.Other than its occurrence in the upper Susitna
River,little is known of the humpback whitefish distribution and habitat
requirements in this reach of river.
3.7 LAKE TROUT
Lake trout were captured in Sally Lake in 1981 and 1982 {ADF&G 1981a,1983a}.
They have not been captured in mainstem or tributary habitats.Sally Lake,at
elevation 2025,will be inundated by the Stage III Watana reservoir.
A total of 62 lake trout were caught in Sally Lake during gillnet and
hook-and-l ine sampl i ng conducted in 1981 and 1982 {ADF&G 1981a,1983a}.The
population size of lake trout in Sally Lake has not been estimated by the mark
.and recapture method,due to insufficient recaptures of marked fish.It is
believed that the population size is small,with approximately 1,000 or fewer
'lake trout inhabiting Sally Lake {ADF&G 1983a}.
3.8 SLIMY SCULPIN
Sl"imy sculpin are apparently distributed in all habitats of the impoundment
:zones.In 1981,38 sculpin were caught in the impoundment zones,while in
1982 no record of sculpin catches was reported {ADF&G 1981a,1983a}.
3.9 CHINOOK SALMON
Salmon are usually prevented from migrating within or upstream of the Devil
Canyon dam site {RM 152}by high water velocities in Devil Canyon.In 1982,
1983 and 1984 a few chinook salmon were observed upstream of Devil Canyon in
four tributaries and tributary mouths.In 1982,21 chinook salmon were
observed in Cheechako and Chinook creeks {ADF&G 1982b}.Thirty-four chinook
salmon were counted in Cheechako,Chinook and Devil creeks in 1983,while in
12
1984,46 fish were observed in Cheechako,Chinook and Fog creeks (Barrett et
al.1984,1985).
Life history information,abundance and distribution data,and habitat-requirements for chinook salmon in the Susitna River have been reported by
ADF&G (ADF&G 1981b,c,1982b,1983b;Barrett et al.1984,1985;Schmidt et al.
1984).
-
1'1"'"
I 13
4,.0 ANTICIPATED IMPACTS
4.1 STAGE I -WATANA RESERVOIR
4.1.1 Inundation
The Stage I Watana reservoir will inundate about 40 miles of the Susitna River
from RM 184 to 224.The stream gradient averages about 14 feet per mile in
th is reach of ri ver (APA 1985b).Steep-wa 11 ed canyons confi ne the ri ver
primarily to a single channel with i~termittent islands.The bed materials
consist mainly of large gravels and cobbles.The Stage I Watana impoundment
will change the physical and chemical characteristics of the Susitna River
between RM 184 and 224 to characteristics associated with the lentic
environment of a large turbid impoundment.
Approximately 15 miles of four named tributaries of the Susitna River will be
'inundated by the Stage I Watana reservoir (APA 1985d).The affected lengths
and stream gradients of these tributaries are listed in Table 5.Addition-
ally,numerous·smaller unnamed tributaries will have portions of their lower
reaches inundated (APA 1983a).A waterfall located about·one mil e upstream
from the mouth of Deadman Creek will be inundated.Thi s waterfa11 prevents
I
upstream movements of fish into upper Deadman Creek.Removal of this fish
barri er will not expand grayl i ng popul at ions into new habi tat because upper
Deadman Creek currently supports a population of Arctic grayling.
Eight 1akes will be inundated by the Stage I Watana reservoir (APA 1985b).
These l~kes range in size from less than one acre to about 10 surface acres in
size.Fish have not been reported to occur in any of these lakes .
..-,
4.1.2 Dr awd own
As previously mentioned in Section 2.1,the Stage I Watana reservoir will
operate in the store-and -re1ease mode.The reservo ir W'j 11 be drawn down from
~October through April and refilled from May through August.The normal
maxi mum drawdown zone will be 150 ft.Due to the drawdown and refill i ng
cycle,about 10 miles of the upper Susitna River between RM 214 and 224 will
14
J J 1 i 1 i 1 »1 1 1 )J 1 i
Table 5.Topographical features of selected tributaries within the proposed stage I Watana
impoundment.
Approximate
length
permanently
inundated (mi)
Approximate
length
in d 2awdown
zone (mi)
Total length
of stream1inundated
(mi)
stream
gradient
of inundated
reach (ftjmi)
Approximate
Elevation at
confluence wj
Susitna
susitna
River
MileTributary
Deadman Creek 186.7 1515 253 2.0 0.6 1.4
f-'
U1 Watana Creek 194.1 1550 60 7.5 2.5 5.0
Kosina Creek 206.8 1670 118 2.8 1.3 1.5
Jay Creek 208.5 1695 143 ....2...t..1 1.0 1.1
Total 14.4 5.4 9.0
1 Assumes normal maximum reservoir level =el.2000.
2 Assumes minimum reservoir level =el.1850.
Source:Adapted from ADF&G 1983a and APA 1985d.
alternate between reservoir and riverine habitat.Reaches of tributaries will
also alternate between reservoir and riverine habitat.The approximate
1engths of the four named tri butari es in the drawdown zone are 1i sted in
Table 5.Three lakes in the Stage I Watana impoundment zone will remain
'"""permanently inundated.Figure 1 shows a schematic of the Stage I Watana
reservoir water surface elevations monthly summary.
4.1.3 Water Quality
(a)General Description
The Stage I Watana reservoi r wi 11 exhibit characteri st i cs si mil ar to deep,
glacial lakes in southcentral Alaska (e.g.Bradley and Eklutna lakes).The
drawdown and refilling cycle,along with the characteristics associated with a
deep,turbid reservoir are expected to affect the fish populations that
presently are found in the upper Susitna Basin.
Water temperatures and suspended sediment and turbidity levels are expected to
be altered significantly by the Watana reservoir.These factors are discussed
i""'"in Sections 4.1.3,b &.c.Dissolved oxygen,nutrients,total dissolved
solids,conductivity,pH,total hardness,total alkalinity,metals and other
water quality characteristics are also expected to change after impoundment;
however,it is anticipated that their levels will not be significantly altered
and will ,,!ot be detrimental to aquatic organisms inhabiting the reservoir (APA
1985d).Therefore,they are not discussed in further detail.
(b)Temperature
-
Under existing conditions,water temperatures in the upper Susitna River range
from near aOc throughout the winter (October through May)to a summer high
near 14 0 C.Instantaneous water temperatures taken by ADF&G from May through
mid-September 1982 recorded a low of a.l oC on May 14 and a high of 13.S oC on
June 24.(ADF&G 1983a).
Tributaries of the upper Susitna River exhibit temperature regimes similar to
the mainstem.Water temperatures are near aOc throughout the winter and reach
IS
.~----
STAGE J.LOAD YEAR 1996
WATANA 200a FT.NO DEVIL CANYON
2050 ....--_-...--,..--r--,.-.-,.--r--.,.--r-...,.--r--,
-2000-t--t-+-r--r--r-r""'-""""""'F==t:::::r--t-1.-r---'-._••
I&.r--
_.-..
r----••••••.••.•~~19SU -1--4--1---1--+-+.-_-._-+---+--t--tr .,...--1---+
~=.....
~r---•.••••
w r---
.J r-'-1LI1900 ~.•:.:;.•::.:..+--+--l---+--+--t--t---t--+---1--r-"i
w •••••.::.:.=:.
~ro·_·~18504--+---+-·'-'·_·:·.:.:..:.=..=.·:·+--+--+---t-~Lt'G~E~N;--"I---t
II::MAX-,_.-.-.
w AVG-t--1-~111 N'•••••••••
~1800 4--+---+--+--+--+--+--+---+--";"+--+--+--1
17504--+---+--+--+--+--+--1r---+--+---+--+--I
....
.JAN FEB MAR RPR MAY JUN JlL RUO SEP OCT NOV DEC
STAGE J.LOAD YEAR ZOO 1
WATANA 2000 FT.NO OEVIL CANYON
2050,--,--...,.--r-.,--,--...,.--r--.,.--r--.-..,..----,
•••••J----i"---j
I---
1--_.......~
-2000 -t--+--+-:--t----t--t----t......-t--.,.............t--+-_+_~~~-r--'-'.
IL t---
Z r---f-._.~1951"1+--+---+--+---+--+::_:,:".=_':t.--+---+-..;.;...r.--:I--+-'---l
tt r'-'>
IoJ
.J •••.•...,::'..:.=
IU 1900 -r-:;.;.;,,;.+--t--t--+-+--+-_+_-+--+--+--+~
IoJ
If
II.a::~1850 -t--t---t--f-";,;;,',;,;,''",'-'.-..-.+---+-+-+--f---+-+----i
1.GENfjI1AX-._.-._.'
~A\lO+---+-
~1BOO -t--t---t--t--+--r---t---+--+M.:.:I~N~·f-"'-'-''+'-''-'-1---4
,'"...
.....
1750 +-:-:-:-+-::::-+-""""'__-+--+--+--+-+--1--+-+-4
..JAN FEB /'tAR APR Ml=lY .JUN .JUL AuG SEP OCl NOV DEC
Figure 1 Stage I Watana Water Surface Elevation
Monthly Summary
ALASKA POWER AUTHORITY
,SUSITNA HYDROELECTRIC PROJECT
r ENTRIX,INC.HARZA -EBASCO
SUSITNA JOINT VENTURE
---l,,.l.,7 ~--____,__-,------------
highs above 15°C during mid-summer.From mid-June to mid-October 1982,
temperatures were recorded continuously in four tributaries of the upper
Susitna River (ADF&G 1983a).The tributary surface water temperatures ranged
from 0 to 16.5 0 C during this period.
The thermal characteristics of the Stage I Watana reservoir will be similar to
deep glacial lakes in southcentral Alaska (e.g.Bradley and Eklutna lakes).
The reservoir is expected to stratify during the summer and winter,while
water temperatures will.approach isothermal conditions (4 0 C throughout the
water column)in the spring and fall.
During mid-summer,when thermal stratification will be the strongest,the
maximum surface water temperature is expected to be between 10 and 12 0 C
(Harza-Ebasco 1985a).Temperatures will decrease with increasing depths to
40 C at depths of 250 to 350 ft.The depth and strength of this stratification
will depend on climatic conditions and will vary from year to year.Stage I
Watana reservoir temperature simulations can be found in a report by
Harza-Ebasco (1985a).
As the reservoir's water temperatures cool,the thermal stratification will
weaken until isothermal conditions prevail (October or early November).
Surface water temperatures will continue to cool until an ice cover forms
(late November or early December)(Harza-Ebasco 1985a).The ice cover is
expected to 1ast into early May.Due to the wi nter drawdown cycl e of the
Stage I Watana reservoi r,ice along the edge of the impoundment wi II fracture
and remain draped on the bank similar to that expected in the Stage III
reservoir (AEIDC 1985).During the winter,temperatures near the bottom will
remain near 40 C while the surface waters just below the ice cover will be near
OOC.Temperatures at a depth of 100 ft are expected to range between 1.5 and
3.00 C during winter (Harza-Ebasco 1985a).Thus,the impoundment will become
inversely stratified.After spring breakup,the reservoir will warm rapidly
due to solar radiation and tributary inflow.
The major changes in the thermal regime of the Stage I Watana impoundment are
that water temperatures are expected to be warmer in the winter and cooler
18
~,
during the summer compared to natural pre-project conditions and the spring
warming and fall cooling rates will be retarded.
(c)Susoended Sediments and Turbidity
Suspended sediment and turbidity levels in the Susitna River are generally
high during spring breakup and summer,with reduced levels in the fall.
During winter,the Susitna River is typically clear.Suspended sediment
values in the mainstem range from winter lows near 10 mg/l to highs of over
5,000 mg/l during the summer at Denali Station (RM 289.5),the gaging station
nearest the glacially-fed headwaters.Maximum summer concentrations at Gold
Creek (RM 138.7)of over 2,000 mg/l have been observed (APA 1983a).
Turbidity values in the mainstem are near zero in the winter.In January and
February 1982,values of 1.1 Nepholometric Turbidity Units (NTU)or less were
measured by the USGS at Gold Creek (RM 138.7)(APA 1983a).Turbidity levels
over 700 NTU have been measured at Vee Canyon (RM 223)during July (APA
1983a).Turbidity le'lels in tributaries of the upper Susitna River are
generally low (20 NTU or less)throughout the year.In these clearwater
streams,peak turbidity and suspended sediment levels occur during spring
breakup and during high flows associated with heavy rainfall events.The
Oshetna River is an exception to this,as its headwaters originate from
glaciers.In 1982 turbidity values in selected tributaries of the upper
Susitna River ranged from near zero in all tributaries sampled to 42 NTU in
the Oshetna River (ADF&G 1983a).
The Stage I Watana reservoir will change the naturally-occurring suspended
sediment and turbidity levels and patterns.Levels in the mainstem will
decrease during the summer compared to natural conditions due to the settling
out of most (80 percent or more)of the suspended sediments as the
sediment-laden Susitna River enters the reservoir.However,the smaller-sized
sediments (particle diameters of 4 microns or less)are expected to remain in
suspension,causing the reservoir to be turbid.Suspended sediment levels in
the reservoir are expected to be between 60 and 150 mg/l during summer and
between 20 and 100 mg/l during winter (APA 1985c).Turbidity levels near the
surface are anticipated to be about 200 NTU in November,decrease to 10-20 NTU
19
--------,----------,-,-------------,-----,----------'
in January through May,increase between May and July to 200-300 NTU and
remain at that level until November (APA 1985c).The reservoir will increase
the summer turbidity and suspended sediment levels in the habitats that were
previously clearwater tributaries.The reservoir will remain slightly turbid
during late winter.Thus,the natural clearwater conditions that prevail in
the mainstem and tributary habitats during the winter will be altered.
Slumping of reservoir walls and resuspension of shoreline sediments will
,....create localized increases in suspended sediment and turbidity.The drawdown
and refilling cycle will tend to aggravate the slumping of reservoir walls
(APA 1983a).
Most of the suspended sediment load of the Susitna River will settle out as
the ri ver enters the reservoi r.Thi s process wi 11 cause the formation of a
delta at the upstream end of the reservoir.The location and extent of the
delta will vary with the drawdown and refilling cycle of Watana and
streamf10ws of the Susitna River.During drawdown,the Susitna River will cut
through the delta and transport sediments farther into the impoundment.
"""Although the tributaries to the Watana reservoir are generally clearwater
streams,they can transport stream bed materials during spring breakup,
periods of heavy rainfall or as a result of bank slides or slumping.
Therefore,it is expected that small deltas may form at the mouths of
tributaries as they enter the reservoir.However,the deltas are not expected-to impede fi sh movements into and out of tri butari es.The 1ocat i on of
tributary deltas will vary with the drawdown and refilling cycle.
The most important change in turbidity levels in the impoundment zone is that
~clearwater tributary habitats will be inundated with turbid water,increasing
turbidity levels throughout much of the year.
,qu>
I
I 4.1.4 Effects on Fi sh
The Stage I Watana reservoir is expected to significantly affect fish
popul at ions in the impoundment area.Inundation,the drawdown and refill i ng
cycle,the reservoir's thermal regime and suspended sediment/turbidity levels
T
I 20
FI'"
:I
are expected to be the dominant forces in altering habitats and subsequently
affecting the populations of fish in those habitats.The anticipated impacts
on species/life stages are described by the habitat types in which the
anticipated impacts will occur.
(a)Tributary Habitat
.(i)Arct ic grayl i n9
The spawning,incubation and rearing life stages of Arctic grayling will
likely be adversely affected by the Stage I Watana reservoir.Spawning
habi tat wi 11 be lost in the reaches of tri butari es inundated by the impound-
ment,because it is expected that grayl i ng wi 11 not ut il i ze the turbi d reser-
voir for spawning.Grayling usually select spawning sites in lotic habitats
(Morrow 1980).Spawning normally takes place during May which is when the
reservoir will be drawn down.If the timing of spawning coincides with
maximum reservoir drawdown,about 9 miles of spawning habitat in the larger,
named tributaries would be lost due to inundation by the reservoir (Table 5).
Spawning will 1i kely occur in the reaches of tributaries within the drawdown
zone.However,i ncubat i on success is expected to be low due to the refill i ng
of the reservoir.Rising water levels will progressively inundate reaches of
tributaries in the drawdown zone.Streambed materials carried downstream by
the high flows of breakup will be deposited at the mouths of tributaries.The
deposition of sediments will move upstream with rising water levels and cover
spawning areas,causing embryo mortality.During May and June (the
approximate period of grayling spawning and incubation)the reservoir's water
level will rise 50 to 55 ft.Thus,in years when the reservoir is at maximum
drawdown (1850 ft)in late April,embryos spawned below el.1905 would be
inundated prior to hatching.
Rearing habitat for Arctic grayl ing in the impoundment is expected to be
limited to the clearwater plumes near tributary mouths.Arctic grayling are
not expected to utilize other areas in the reservoir as grayling are not found
in lakes with turbidity levels similar to those anticipated in Watana (Russell
1980).Some displaced grayling will likely use rearing habitats in tributary
21
....
reaches above the reservoir water levels.However,rearing habitats in
tributaries are thought to be already occupied,as indicated by the high
densities of grayling per mile (323-1835)reported by ADF&G (1983a).Thus,
important tributary habitat will be lost,reducing Arctic grayling populations
in the upper Susitna River.It is estimated that the mid-summer population
size of Arctic grayling inhabiting tributary reaches inundated by the Stage I
Watana reservoir is about 10,000 fish greater than 150 mm in length (Table 2).
Most Arctic grayling in the upper Susitna River apparently overwinter in the
mainstem,although some may remain in tributaries throughout the winter.
Overwintering conditions may improve in habitats inundated by the impoundment
due to the warmer water temperatures in the reservoir.Present winter water
temperatures in the mainstem and tributaries are near OOC.Winter
temperatures at a depth of 100 ft in the Watana reservoir will be in the range
of 1 to 20 C (Harza-Ebasco 1985a).The warmer water temperatures may increase
.the .overwintering survival of fish in the impoundment,as it has been noted
that fi sh are attracted·to warmer water temperatures duri ng wi nter (Umeda et
al.1981).
In the fall and early winter,turbidity levels in the reservoir (200-300 NTU)
are expected to restrict overwintering grayl ing to areas near the inflow of
tri butari es.After December,when reservoi r tu'rbiditi es decrease to 10-20
NTU,grayling will likely expand their distribution in the reservoir.
Table 6 summarizes the anticipated impacts of the Stage I Watana reservoir on
the life stages of Arctic grayling inhabiting tributaries in the impoundment
area.The spawning,incubation and reari ngli fe stages will 1 ike1y experience
adverse impacts.Overwintering habitat may improve under with-project
conditions.However,this is not expected to offset losses expected during
the other life stages.
(ii)Dolly Varden
The Stage I Watana reservoir is expected to have insignificant effects on
Dolly Varden populations in tributaries of the upper Susitna River.DollyTVardenoccupyawiderangeofhabitattypesinsouthcentralAlaska,including
I
~22
i
o __~._~.~---~-_
t
I
I
Table 6.Summary of selected species relative abundance,sport value and
sensitivity to habitat alteration in tributary habitats of the proposed
Stage I Watana impoundment zone.
1 1 =low,2 =moderate,3 =high.
2 0 =no predicted change or,may be positive influence;1 =low;2 =moderate;
3 =high.Refer to text for discussion of species sensitivity to potential
impacts.
23
-~-----------------------------
1i"F'"
I
I
I
~r
I
I
'!
I
I
glacial lakes with a wide range of water quality (Russell 1980).Thus,it is
anticipated that Dolly Varden will occupy the Stage I Watana reservoir
throughout much of the year.Dolly Varden spawn in tributaries during the
fall (October to November)(Morrow 1980).After impoundment,it is 1i kely
that they will continue to use tributaries for spawning.Since Dolly Varden
spawn in the fall when the reservoir's water levels will be stable or
decreasing,incubating embryos in tributaries will not be inundated by rising
water levels.Dolly Varden may spawn along the margins of the reservoir.If
this occurs,incubating embryos will be dewatered due to reservoir drawdown.
Dolly Varden will likely utilize the Stage I Watana reservoir during the
summer for rearing.However,turbid conditions and the drawdown and refilling
cycle are expected to limit the development of littoral areas and productivity
of the impoundment (APA 1985d).These conditions will likely concentrate the
distribution of most fish in the reservoir near the clearwater plumes of
tributary inflow.
As discussed previously,it is expected that overwintering conditions in the
Stage I Watana Reservoir may improve over those that presently occur in
r tributaries and the mainstem.Dolly Varden will likely utilize the reservoir
I during the winter •
.1"'"
:The anticipated effects of the Stage I Watana Reservoir on Dolly Varden
populations in tributaries are summarized in Table 6.
'I
.1
r
'I
(b)Mainstem Habitat
(i)Burbot
Burbot occupy the mainstem of the upper Susitna River throughout the year.
After impoundment,mainstem habitats will be eliminated and replaced by a
turbid impoundment.Since burbot are found in glacial lakes in southcentral
and southwestern Alaska (Bechtel Civil and Minerals,Inc.1981;Russell 1980),
they will likely utilize the Stage I Watana reservoir year-round.
24
....
-
The winter dralt11dowll of the Stage I Watana reservoir is expected to affect the
incubation success of burbot in the impoundment.In lakes,burbot usually
spawn in mid-winter (January to early March)in relatively shallow water (20
ft or less)with their eggs settling to the bottom (Morrow 1980).The Stage I
Watana reservoir will be drawn down from November to May at an average rate of
0.7 ft per day.Thus,embryos in shallow water will become dewatered anC!
freeze.This ,~ill substantially reduce the recruitment to burbot populations
occupying the impoundment.Some burbot in the impoundment area may move into
the upper Susitna River to spawn,where incubation success would be unaffected
by reservoir drawdown.
The reari ng alrld overwi nteri ng 1i fe stages of burbot are not expected to
experience advlerse impacts from the project.Overwintering-conditions may
improve after impoundment,due to the warmer winter temperatures.It is
expected that burbot populations may expand over existing conditions.However
densities are elnticipated to remain low due to reduced recruitment and the low
productivity of the impoundment.
Table 7 summarizes the anticipated impacts of the Watana reservoir on the life
-stages of burbot.
(ii)Arctic grayling
.-.
-
Some juvenile Arctic grayling use clearwater sloughs in the mainstem and
tri butary mouths for summer reari ng.It is expected that the Stage I Watana
reservoir will not have significant effects on these fish as replacement
habitat will likely exist near the tributary mouths in the reservoirs.
Most Arctic grayl ing in 'upper Susitna River tributaries apparently move into
the rna i nstem for overwi nteri ng.Overwi nteri ng cond it ions for grayl i ng under
existing and with-project conditions have been discussed previously
(Section 4.1.4).It is expected that overwintering conditions may improve
under project operation,due to warmer water temperatures.
A summary of the anticipated impacts of the Stage I Watana reservoir on Arctic
grayl i ng in ma i nstem habitats is presented';n Tabl e 7.
25
.....
Table 7.Summary of selected species relative abundance,sport value and
sensitivity to habitat alteration in mainstem habitats of the proposed
Stage I Watana impoundment zone.
Relative sensitivity
Relative Relative of speci es/l i fe
abundance in sport valu,stage to
Species Life stage mainstem habitat l of species habitat alteration 2
Burbot spawning 1 1 0
rr-incubation 1 1 3
rearing 1 1 0
overwintering 1 1 0
!!-.....
Arctic grayling rearing 1 3 0
overwintering 3 3 0r-
Dolly Varden overwintering 1 1 0
1 1 =low,2 =moderate,3 =high.
2 0 =no predicted change or,may be positive influence;1 =low;2 =moderate;
3 =high.Refer to text for discussion of species sensitivity to potential
impacts.
-26
(iii)Dolly Varden
Dolly Varden may util ize mainstem habitats for overwintering.As discussed
previously,overwintering conditions will likely improve under project
operation due to warmer water temperatures of the reservoir.Thus,if Dolly
Varden do overwinter in the mainstem,conditions are expected to improve under
~with-project operation (Table 7).
(c)lake Habitat
,.....
....
Most lakes inundated by the Stage I Watana reservoir are apparently barren of
fish.These lakes are primarily small,perched tundra lakes.One lake .on the
south side of the Sus i tna Ri ver across the ri ver from the Watana Creek mouth
is reported to contain Arctic grayling (ADF&G SuHydro,unpublished data).The
i nundat i on of 1akes by the Stage I Watana reservo ir is expected to have
insignificant effects on fish populations.
4.2 STAGE II -DEVIL CANYON RESERVOIR
4.2.1 Inundation
The Devil Canyon reservoir will inundate about 31 miles of the Susitna River
from RM 152 to 183.From Watana (RM 184)downstream to Devil Creek (RM 161)
the stream gradient averages 11 ft per mile,while between Devil Creek and
Devil Canyon (RM 152)the gradient increases to 31 ft per mile (APA 1983a).
Steep canyon walls confine the river to a single channel throughout most of
the river between Devil Canyon and Watana.About six miles of the lower
reaches of five named tributaries will be inundated (Table 8),plus the lower
reaches of numerous smaller,unnamed tributaries.Inundation will change the
physical and chemical characteristics of the riverine habitats to those
associated with a large,turbid impoundment.
Many of the tributaries in the Devil Canyon impoundment area are characterized
by high stream gradients with occasional waterfalls.Cheechako,Devil and
Tsusena creeks all contain waterfalls.However,none of these waterfalls will
27
I ]J )J ]i 1 I 1 B ]
Table 8.Topographical features of selected tributaries within the proposed Devil Canyon
impoundment.
Approximate stream Total length Approximate Approximate
susitna elevation at gradient of stream length length
River confluence of inundated inundated1 in d 2awdown permanently
Tributary Mile with Susitna reach (ft/mi)(mi)zone (mi)inundated (mi)
Cheechako Cr.152.4 920 321 1.7 0.4 1.3
Nco Chinook Cr.157.0 1065 308 1.3 0.4 0.9
Devil Cr.161.4 1200 176 1.5 0.7 0.8
Fog Cr.176.7 1375 72 1.3 1.3 0.0
Tsusena Cr.181.3 1435 82 .Q.d..Q.d..Q.&
Total 6.2 3.2 3.0
1 Assumes normal maximum reservoir level =1455 ft MSL.
2 Assumes minimum reservoir level =1405 ft MSL.
Source:ADF&G 1983a and APA 1985d.
,.,..
-~
be inundated and would still function as barriers to upstream fish passage
after impoundment.
One five-acre lake will be filled by the saddle dam during construction (APA
1983a).No lakes will be affected by impoundment of the Devil Canyon
Reservoir.
4.2.2 Drawdown
Due to the nature of the two-dam system,Devil Canyon impoundment will operate
at full pool (1455 ft)for most of the year (APA 1983a).Duri ng wet years
there will_be no need to drawdown the reservoir.However,during average and
dry years,drawdown will occur during July,August and early September.The
drawdown will help meet power production needs and downstream flow releases
while the Stage I Watana reservoir is refilling.The normal maximum drawdown
zone for Devil Canyon is expected to be 50 ft.Thus,the magnitude,timing
and duration of drawdown for Devi 1 Canyon reservoi r is qui te di fferent from
the Stage I Watana drawdown (Section 4.1.2).
About fi ve mil es of the Sus i tna Ri ver between RM 178 and 183 will alternate
between reservoi r and riverine habitat due to the drawdown of Devil Canyon
reservoir.Reaches of tributaries within the impoundment area will also
alternate between reservoir and riverine habitat.The approximate lengths of
the five named tributaries in the drawdown zone are listed in Table 8.A
schematic of the monthly summary of·water surface elevations in the Devil
Canyon reservoir is shown in Figure 2.Figure 3 shows the Stage I Watana
water surface elevations with Devil Canyon operating.
4.2.3 Water Quality
(a)General Description
The water quality in the Devil Canyon reservoir will be similar to that in the
Stage I Watana reservoir (Section 4.1.3).The impoundment is expected to
signi fi cantly alter water temperatures and suspended sediment and turbidi ty
29
-
-
-I
......
STAGE It,LOAD YEAR 2002
WATANA 2000 FT.DEVIL CRNYON 1455 FT.(ORAWDOWN 50'}
1500 ..,...-r----r-...,...-.,..---,.-....,..--..,.-.-,-....,...--r--r----,
-1475 +--+---+--+--+--+--+---I---Ir---l--+--t--t
~....
~1450 4-=-=:rI="-=-=t-=-=:t~-=~+-:·~·"""'·:::::·=I"~·.:.,:'-~":':>-~'-=.:.:'-~.~-~.-~-='=-+=:~I:::=:-~""::':"::'1=-=-=t-1
l""a:>
l&J
...I
UJ 1425+--+---+--I--+--+--+---I---Ir---t--+--t--t
l&J
~....
0::~1-00 -+--I---+--+--+---r--+--+----r---L+-QE-N1-+--I----1
a::MAX - •_.- "_.
~AVO+-~---
~1375 +-_I---+_-I-_+--+_-+-_+---I~M.;.;IN..;.."+-·_·._.'-+'_"_'-1-~
1350 -t---:I---+--+--+--+--I--+---I--+---t--I---t
.JAN FEB MAR _APR MAY JUN JUL.AUG SEP OCT NOV DEC
STAGE If.LOAD YE~R 2007
WATANA 2000 FT.DEVIL CANYON 1455 FT.
-1475+---I--+--+--+--I--+---+--+--t--I--+---I
~....
~t 450 .t=~r=::t=:t=~=::t:""::~.:;:~.~~.:-~.-4·;.:-:·:;-~-=·=-t-="=-:t::-::::·~=1........a:>
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\oJu
(I
~
~1400+---I--t--+--+--I--+---+--I--t--+--t---+L GENla:MAX-._.
~AVO+-~-
~1375 +---Ir---t---I--+--1--+--+--+-I1 ..;..'N_ot-
0
_"-_""+"_""_"-t---+
1350 +---Ir---t--+--+--I--+--+--+--+--+--t---+
..JAN FEB MAR APR HAY JUN JUL AUO SEP OCT NOV DEC
Figure 2 Stage II Devil Canyon Water Surface Elevation
Monthly Summary with Stage I Watana Operating
ALASKA POWER AUTHORITY
.SUSITNA HYDROELECTRIC PROJECT
.-ENTRIX,INC.
30 "
HARZA -EBASCO
SUSITNA JOINT VENTURE
......
I
STAGE JI.LOAD YEAR 2002
~ATANA 2000 FT.DEv I L.CANYON 1455 FT.(DRAI..JOru-lN 50')
-2000 ;--l----T--+--;--t--t--+--+--~=t-._-._+--+
t r--~
f---
_._f--_.
.....r--
~
I--
'-'-...........t--a1950 -+"'-'---+--+--+--+--;-:'~-:.:.'",.---+---+--,..'-''-''-t'~:-+--....;;:-.-.........
cr ._.-
>!oJ
..J
~1900 +--t-.-..-..-l:::::=:1---+--+---+--+---i--+--+-+---1
a.Jua;
u-
lr~1850 -l-_+--+_-+-_-f._A
_.'-'.-r----f--+--+--+---I--!---I
L GENl
lr I1AX-._.-'_A
~AvG-+--;-
a;HI N'•••••••A'
:I 1800-1--+---+--+---+--+---+--+-+":"';'+--1---+--1
-.
-
1750-l--+---+--+_-+-_+---+_--I-_+_+---I.---!-_-I
.JAN FEB HAR RPR HAY JUN JUL AUG SEP OCT NOV OEC
STAGE II.LOAD YE~R 2007
WATANA 2000 FT.DEVIL CANYON 1455 FT.
2050 -r--r---,..-""T"""-,....--.,.-....-,----,---r--,.---;;---,
._.-
I'-
f-._.
I--
,-
...._-.....
-2000 -l--I---!---+--+--+--!---j::'=:'===!--I::=r-f----,
~u..
z
;1950 R
a;•
~"';:'-..J •••••~1900 ......._.-w .........-
u ._.-ct ••.•.-_.-
lE .••..,r::-=:
~1850 -+-~i----+--+--l--+--l---I----r--+---+---l---1
L GEM
lr MAX ._.
~AVG-+---If--
~IS00+---I--+--+-__f----I---+--+---TM;.;.;I:.....N;...·f-"-'-"+"-"-'-+---I
-
.-
1750;-__.---+--+--\----+--+-+--+--t-_+---i.---I
JRN FEB MAR APR HAY JUN JUL.AUG SEP OCT NOV DEC
Figure 3 Stage I Watana Water Surface Elevation
Monthly Summary
with Stage II Devil Canyon Operating
ALASKA POWER AUTHORITY'
SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.HARZA -EBASCO
SUSITNA JOINT VENTURE
':\1
-
-
-
-
levels of mainstem and tributary habitats.Other water quality parameters are
not expected to change significantly (Section 4.1.3).
(b)Temperature
Baseline water temperature conditions in the upper Susitna River and its
tributaries were described in Section 4.1.3(b).
The temperature regime of the Devil Canyon reservoi r is expected to be simil ar
to the Stage I Watana reservoir temperature regime.The Devil Canyon reser-
voir will experience weak summer and winter thermal statifications,inter-
rupted by ;sotherma 1 condi t ions in the fall and spri ng.Water temperatures
during the summer in the Devil Canyon reservoir are expected to be cooler in
comparison to pre-project conditions,while winter temperatures will be warmer
than natural conditions.The fall cooling and spring warming periods are
expected to shift,lagging behind natural conditions.The Devil Canyon
reservoir temperature simulations are presented in reports by Harza-Ebasco
(l985a,1985b).
Due to its smaller size (7,800 surface acres,1.09 million acre-feet)compared
to the Stage I Watana reservoir (20,000 surface acres,4.3 million acre-feet),
the Devil Canyon reservoir will likely respond to meteorological conditions
more rapidly,and in particular will be more susceptible to wind mixing.
The maximum surface water temperatures in the Devi 1 Canyon reservoi rare
expected to be in the range of 10 to 12 0 C in August.During winter,an ice
cover is expected to form on the reservoi r by 1ate November,1 ast i n9 until
early May (Harza-Ebasco 1985a).Simulations indicate that winter water
temperatures will be in the range of 2 to 40 C at a depth of 50 ft
(Harza-Ebasco 1985a).
(c)Suspended Sediments and Turbidity
Suspended sediments of 1ess than 4 mi crans in di ameter wi 11 enter the Devil
Canyon reservoir from the Stage I Watana reservoir.Only a small percentage
of this suspended sediment is expected to settle out.Thus,suspended
32
-
sediment 1evel s wi 11 generally ref1 ect those occurri ng in the Stage I Watana
reservoir (Section 4.1.3,c).
Due to the settling out of most sediments in the Stage I Watana reservoir,an
extensive delta will not form at the upstream end of the Devil Canyon
reservoir.Small deltas will likely form at the mouths of tributaries,
similar to those expected in the Stage I Watana reservoir.
..-
,-
Some slumping of reservoir walls and resuspension of shoreline sediment will
occur,particularly during reservoir drawdown.However,since the overburden
layer is shallow,slumping and sediment entrainment should not create
significant problems.Thus,increases in suspended sediment and turbidity
levels will be localized and short-term.
Turbidity levels in the Devil Canyon reservoir are expected to follow the
pattern and range of levels in the Stage I Watana reservoir.Turbidity values
are expected to be lowest during the spring and increase during late summer
and early fall (Section 4.1.3,c).
The most important change in turbidity levels from natural conditions is that
clearwater tributary habitats will be inundated by turbid water,increasing
turbidity levels throughout much of the year.
4.2.4 Effects on Fish
The Stage II Devil Canyon reservoir will affect fish populations inhabiting
the upper Sus i tna Bas in.Inundation,drawdown and refi 11 i ng,and the reser-
voir's thermal regime and suspended sediment/turbidity levels are expected to
r-be dominant forces in altering habitats.The anticipated impacts on species/
1i fe stages are descri bed by the habi tat types in whi ch impacts wi 11 occur.
(a)Tributary Habitat
The major alteration of tributaries is the inundation of these clearwater
10tic habitats with a turbid reservoir.Anticipated impacts to fish species
33
,.".,
"'""
-
in tri butary habitats are expected to be simil ar to those presented in
Section 4.1.4(a)for the Stage I Watana reservoir.
(i)Arctic grayling
Arctic grayling are not expected to spawn in the turbid reservoir,as they
prefer lotic habitats.The Devil Canyon reservoir will be at full pool (el.
1455)during the grayling spawning and incubation periods (May-June).Thus,
about six miles of habitat in the larger,named tributaries would be lost due
to inundation (Table 8).Because the reservoir will be at full pool,any
spawning that occurs in tributaries upstream of the reservoi r's water 1evel
will not be affected by the drawdown and refilling cycle.
Rearing conditions for Arctic grayling in the reservoir will be similar to
those in the Stage I Watana reservoi r (Sect ion 4.1.4).It is expected that
most of the 1,200 grayling residing in tributaries within the impoundment area
(Table 3)will be displaced and lost.
The Devil Canyon reservoir may improve overwintering conditions for Arctic
~grayling in the impoundment area.The winter water temperatures are expected
to be in the range of 2 to 40 C at a depth of 50 ft (Harza-Ebasco 1985a).
Warmer than natural temperatures may improve the overwi nteri ng survi va 1 of
fish.
Tabl e 9 summartzes the impacts of the Devil Canyon reservoir on the 1i fe
stages of Arctic grayling inhabiting tributaries within the impoundment area.
(ii)Dolly Varden
The Devil Canyon reservoir is expected to have insignificant effects on Dolly
Varden populations in the upper Susitna Basin.Dolly Varden are expected to
utilize the Devil Canyon reservoir throughout much of the year.
....
Dolly Varden will likely spawn in tributary reaches above the reservoir's
water level after impoundment.Some incubating embryos may be affected by the
refill ing cycle.Spawning occurs in October and November,which is when the
34
Table 9.Summary of selected species relative abundance,sport value and
sensitivity to habitat alteration in tributary habitats of the proposed
Devil Canyon impoundment zone.
-Species
Relative abundance Relative
of species in 1 sport valuy
Life stage tributary habitat of species
Relative sensitivity
of species/life
stage to
habitat alteration 2
.....
..-
I
.-
Arctic grayling spawning 3 3 3
incubation 3 3 3
rearing 3 3 3
overwintering 1 3 0
Dolly Varden spawning 1 1 1
incubation 1 1 0
rearing 1 1 1
overwintering 1 1 0
1 1 =low,2 =moderate,3 =high .
2 0 =no predicted change or,may be positive influence;1 =low;2 =moderate;
3=high.Refer to text for discussion of species sensitivity to potential
impacts .
35
--
-
.-
.....
,-
-
reservoir will be filling during normal or dry years.Embryos spawned in the
drawdown zone will experience higher mortality due to inundation and siltation
(Sect ion 4.1.4).
The Devil Canyon reservoir is not expected to provide favorable conditions for
rearing fish.The steep walls and turbidity will inhibit the development of a
littoral area and productivity of the reservoir.Similar to the Stage I
Watana reservoir,it is expected that most fish will be distributed near the
inflow of tributaries.
Table 9 summarizes the anticipated effects of the Devil Canyon reservoir on
Dolly Varden populations in tributary habitat.
(b)Mainstem Habitat
(i).Burbot
Burbot are found in glacial lakes in southcentral and southwestern Alaska
(Russell 1980)and are expected to utilize the Devil Canyon reservoir
throughout the year.Unl ike the Stage I Watana reservoir,the Devil Canyon
reservoir's water level will be stable during winter.Thus,the drawdown and
refilling cycle of the reservoir will not affect burbot embryo incubation .
No significant impacts are anticipated for burbot inhabiting the Devil Canyon
reservoir (Table 10).
(ii)Arctic grayling
No significant impacts are anticipated for Arctic grayling in mainstem
habitats inundated by the Devil Canyon reservoir (Table 10).Conditions are
expected to be similar to those dicussed in Section 4.1.4.
(iii)Dolly Varden
The anticipated effects of the Stage I Watana reservoir on Dolly Varden in
mainstem habitats (Section 4.1.4[bJ)are expected to be similar for the Devil
Canyon Reservoir.No significant impacts are foreseen.
36
Table 10.Summary of selected species relative abundance,sport value and
sensitivity to habitat alteration in mainstem habitats of the proposed
Devil Canyon impoundment lone.
Species life stage
Relative abundance Relative
of species in sport valu~
mainstem habitat1 of species
Relative sensitivity
of species/life
stage to
habitat alteration 2
.....
Burbot spawning
incubation
rearing
overwintering
Arctic grayling rearing
overwintering
1
1
1
1
1
3
1
1
1
1
3
3
oooo
a
a
Dolly Varden overwintering 1 1 o
-
-
1 1 =low,2 =moderate,3 =high.
2 0 =no predicted change or,may be positive influence;1 =low;2 =moderate;
3 =high.Refer to text for discussion of species sensitivity to potential
impacts.
37
-
(iv)Chinook Salmon
-A few chinook salmon migrate upstream of Devil Canyon (RM 152)to spawn.
Construction of the Devil Canyon dam will prevent chinook salmon from-utilizing habitats upstream of the dam site.
4.3 $TAGE III -WATANA RESERVOIR
4.3.1 Inundation
The Stage III Watana reservoir will inundate an additional 11 miles of Susitna
River from RM 224 to 235.Approximately 12 miles of six named tributaries.
will be inundated by the Stage III reservoir (Table 11).The total length of
the named tri butari es inundated by both Stage I and Stage II lis about 26
miles.Additionally,numerous,unnamed tributaries will also be affected by
the Stage III impoundment.
Twenty-three lakes will be inundated by the addition of the Stage III Watana
reservoir.Most of the lakes are relatively small,as 22 lakes are less than
10 surface acres.Sally Lake,with a surface area of 63 acres and a maximum
depth of 27 ft,is the 1argest 1ake affected by the Stage III Watana
reservoir.Sally Lake is located on the north side of the Susitna River near
the mouth of Watana Creek at an elevation of 2025 ft.
4.3.2 Drawdown
The Stage III Watana reservoir will be operated similar to Stage I Watana:
the store-and-release mode.The Stage III reservoir will be drawn down from
October through April and refilled from May through August.The normal
maximum drawdown zone will be 120 ft.Stage III Watana water surface
elevations are shown in Figure 4.Figure 5 is a schematic of the Devil Canyon
water surface elevations with Stage III Watana operating.
-Due to the drawdown and refill i ng cycle,about 9 mi 1es of the upper Susi tna
River between RM 226 and 235 will alternate between reservoir and riverine
habi tat.Reaches of tri butari es wi 11 also alternate between reservoi rand
38
-J -J ]1 }J ]-1 1 ]J
Table 11.Topographical features of selected tributaries within the proposed Stage III Watana impoundment.
Tributary
Susitna
River Mi le
Approximate elevation
of confluence with
Susitna
Stream gradient
of inundated
reach (ft/mi)
Estimated Approximate Approximate length
length of stream inyndated {mil length in drawdown permanently
Stage I Stage III Total zone 2 (mi)inundated (mi)
Deadman Creek 186.7 1515 253 2.0 0.7 2.7 0.5 2.2
Watana Creek 194.1 1550 60 a 7.5 1.0 a 0.0 8.58.5 bEastForkMIA2060c113b0.0 1.2 1.2b 1.1 0.1
West Fork MIA 2060 c 67 b 0.0 2.1 2.1 1.8 0.3
Kosina Creek 206.8 1670 118 2.8 1.7 4.5 1.0 3.5
LV
\.0 Jay Creek 208.5 1695 143 2.1 1.4 3.5 0.8 2.7
Goose Creek 231.3 2060 114 0.0 1.2 1.2 1 .1 0.1
Oshetna River 233.4 2110 41 ....Q.:.Q ....L1.....L1..Ll 0.0
Total 14.4 11.5 25.9 8.5 17.4
1 Assumes normal maximum reservoir level =el.2185.
2 Assumes minimum reservoir level =el.2065.
a Watana Creek below forks.
b Watana Creek above forks.
c Elevation at confluence of Watana Creek forks.
Modified from ADF&G 1983a and APA 1985d.
--
....
-
-
-
-
STAGE I I I .LOAD YEAR 2008
WATRNA 2185 FT.OEv lL CANYON 1455 FT.
2200
ro'-----0_._
---:..::.:----r---I-1----.._..-
-2150 .."......-
...-._..-.---.....................
IL.-._.._.--.............
..........f----,..-.......a ..Z
~2100
l-...................a:>.....
W ......
.J
W2050
wua:u.
lr~2000 L F-GEN!a::MAX--_.-._.
w·Ava~a:HIN'....,....'".......
:z 1950
1900
JRN FEB MAR f=lPR HAY JUN ...JUL RUG SEP OCT NOV DEC
STAGE 1r I.LOAD YEAR 2020
WATRNA 2185 FT.DEVIL CRNYON 1455 FT.
2200
,.,---.-.._----'I----._.
-2150 1---'...................
f----t-.......
IL.~._.........---_.-..........
z -_......
~2100 ......-.........---
I----:---_..a:...............~
I--->.....
lY .....
.J
UJ2050
\oJ
Ua:u..
tr
~2000
t1A/F-GEN!
It:--.w AvaI-a:HIN'...................
:1:1950
1900
JAN FEB HAR APR HAY JUN JUL !=lua SEP OCT NOV DEC
Figure 4 Stage III Watana Water Surface Elevation
Monthly Summary
ALASKA POWER AUTHORITY
.SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.HARZA -EBASCO
susrrNA JOINT VENTURE
40
.....~
I---
--_._--------------------------------,STAGE Ill.LOAD YEAR 2008
WATANA 2185 FT.DEVIL CRNYON 1455 FT.
1500 _-.,......--..---..,..-..,.....-~-r____r-__r_-_.__-.,..___,.-.....,
-1475 +--+---I--+--+--+--I---t--+---l--+---+--l
l-
ll..
Z 1---+---+---+--+--1~.--.-0-"--.-~_I----l---1~14504--+---l---l---1---t===I---4---F==t===+--+-~
I-a:>
'"-I
..J
LU 1425-1--+---+---1---I---I--I~--I---I---I--l--~--I
lIJ
Ua:u..
lr
~1400 -+--+---1--+--1---1--1--1---1---1--1---10--1
L GENI15MAX- •- •- "- •
I-I=lVO-l---1-
~1375 +-_+---+_-l-_+-_+--I.--I-_+M~IN:";'"-l-'_'_""_-1-""_0'-1---1
1350 +--+---+--l--+--+---I---1---I---l---~-I---I
..JRN FEB /'1RR RPR HAV JUN ...lUL I=lUO SEP OCT NOV DEC
STAGE Ill.LOAD YEAR 2020
WATANA 2185 FT.DEVIL CRNYON 1455 FT.
1500 -r--T----r--r--...,....-,----,---,---r--.,....--r--...,.-~
_1475 +--+---+--l--+--+---I--+--+--4--~-I---l
l-
ll.-
~1450 -+--+---+--I--+-~..,....~.===-:l,.'==-=='-.--'.-,*=-::::'-:~I--~"=-~==.:t
l-
t[
>
lIJ
..J
LaJ 1425 -+-_+---+_--!-_-I-_-I---I_''_0_00-l--I~--l---1-.._.._...j.._~
'"-I
U
t[u..
lr
~I 400 -+--+---+--+---!--+---+---+---1--L-l-GE-~Nl-4---+--l
15 MRX"._0_0_"
...I=lVG,-+-----~
~1375 +-_+---+_-I-_+-_+---+_--1-_-+:-:M..:...,:1N":"·-I-°_""-"'-1-"'-''--l---J,
1350 -t--+--J,--+---l---t-.---l-4-4--+-.-!l---I----l
Figure 5 Stage II Devil Canyon Water Surface Elevation
Monthly Summary with Stage III Watana Operating
ALASKA POWER AUTHORITY
,SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.
41
HARZA -EBASCO
SUSITNA JOINT VENTURE
riverine habitat.Table 11 shows the approximate lengths of the six,named
tributaries in the drawdown zone.Most lakes,including Sally Lake,will
remain inundated during drawdown.
4.3.3 Water Quality
The water quality associated with Stage III Watana reservoir is expected to be
similar to that of Stage I Watana reservoir.The only significant change
expected at th is time is for wi nter water temperatures in the Stage I II
impoundment to be 1 to 1.50 C warmer than the Stage I reservoir (APA 1985).
This is attributed the larger reservoir volume and longer retention time
associiated with the Stage III reservoir.Ice formation on the Stage III
reservoir will occur about mid-November and last until early May (Harza-Ebasco
1985a).
4.3.4 Effects on Fish
The Stage III Watana reservoir will alter habitats and affect fish populations
similar to the Stage I Watana reservoir.Inundation,drawdown,water
temperatures and turbidity/suspended sediment levels will continue to be the
dominant forces affecting habitats and fish populations.Anticipated impacts
associated with the Stage III Watana reservoir are discussed by the habitats
in wh"ich they will occur.
(a)Tributary Habitat
Alrctic:grayl ing and Dolly Varden inhabiting tributary reaches inundated by the
Stage III Watana reservoir will be affected in ways described in Section 4.1.4
for the Stage I Watana reservoir.No significant impacts are expected for
Dolly Varden.However,inundation of about 11.5 additional miles of the
largelr named tributaries will affect habitat utilized by an estimated 8,800
A'rctic grayling (Table 2).It is likely that most of the graying inhabiting
clearlflater tributaries inundated by the reservoir will be displaced and lost.
42
",.,.
(b)~ainstem Habitat
Anticipated impacts of the stage I Watana reservoir on fish inhabiting the
mainstem were discussed in Section 4.1.4.It is expected that the Stage III
Watana reservoir will affect mainstem habitats and fish populations in similar
ways.The dewateri ng of burbot embryos spawned in shallow areas of the
reservoir will continue to reduce recruitment to burbot populations of the
upper Susitna River.
(e)Lake Habitat
(i)Arctic grayling
Arctic:grayling occur in Sally Lake,which will be inundated by the Stage III
Watana reservoir.The effects of the impoundment on grayling are expected to
be similar to those discussed previously (Section 4.1.4).The spawning,
incubation and rearing life stages will likely experience adverse impacts
(Table 12).
(ii)Lake Trout
A sman population of lake trout occurs in Sally Lake.Lake trout from Sally
Lake are expected to survive in the Watana reservoir as 1 ake trout are found
il"l glacial lakes in southcel"ltra1 Alaska (Bechtel Civil and Minerals,Inc.
1981,Russell 1980).
Lake trout will likely spawn in the Stage III Watana reservoir.However,
incubating embryos will be affected by the drawdown cycle.Lake trout usually
spawn from 1 ate September to November at depths ranging from 3 to 110 ft
(l\1orrow 1980).Drawdown (November to May)in the Stage III Watana reservoir
will ,average 0.5 ft/day.As a result,embryos incubating in the upper 50 to
60 ft of the reservoir will be dewatered by March 1 (the approximate end of
the incubation period),causing incubation success to be low in the drawdown
lone.
43
Table 12.Summary of selected species relative abundance,sport value and
sensitivity to habitat alteration in lake habitats of the proposed
r-Stage III Watana impoundment zone.
SlPecies Life stage
Relative abundance Relative
of species sport valuy
in lake habitat1 of species
Relative sensitivity
of species/life
stage to
habitat alteration 2
.....
Arct ic glrayl i ng spawning 2 3 3
incubation 2 3 3
rearing 2 3 3
overwintering 2 3 0
lake trout spawning 1 3 0
incubation 1 3 2
rearing 1 3 1
overwintering 1 3 0
1 1 ==low,2 =moderate,3 =high.
2 0 ==no predicted change or,may be positive influence;1 =low;2 ==moderate;
3 ==high.Refer to text for discussion of species sensitivity to potential
impacts .
44
The drawdown and refill i ng cyc1 e and turbidi ty 1eve1 s of the Watana reservoi r
are expected to 1 imit the development of a 1 ittora1 zone and restrict the
productivity of the Stage III impoundment.Therefore,it is likely that
rearing conditions will not be favorable in much of the reservoir.However,
the clearwater plumes of tributaries are expected to provide favorable rearing
habi talts for fi sh.Lake trout may frequent these areas because of the.....
ava i1 abi 1i ty of prey.It is expected that the growth rate of 1ake trout wi 11
be low because of the anticipated low productivity of the impoundment.
Overwintering conditions in the Watana reservoir will likely have
insignificant effects on lake trout.The expected effects of the Stage III
Watana impoundment on lake trout populations are summarized in Table 12.
45
-i
5.0 SELECTION OF EVALUATION SPECIES
All three mitigation pol icies (APA 1982,ADF&G 1982a and USFWS 1981)imply
that project "impacts on certain sensitive fish species will be of greater
concern than changes in distribution and abundance of less sensitive species.
Sensitivity can be related to high human use value as well as susceptibility
to change because of project impacts.Statewide pol icies and management
approaches of resource agenci es suggest that concern for fi sh and wi 1dl i fe
species with commercial,subsistence and other consumptive uses is greater
than for species without such value.These species are often numerous,and
utilize a wide range of habitats,as well as having high human use value.
Such characteristics often result in these species being selected for detailed
evaluation when their habitats are subjected to alterations.
In the impoundment zone,Arctic grayling are abundant and widespread in
tlributary habitats during summer,and reside in the mainstem during winter.
This species has a high human value,as it is highly prized by sport
fishermen.Grayling populations in the impoundment zones contain some fish
that are of trophy size,such as the Deadman Creek population (Schmidt and
Stratton 1984).Based on impact assessments presented in the original license
application (APA 1983b),the license application amendment (APA 1985d)and in
Section 4.0 of this report,it is expected that the impoundments will not
provide suitable spawning,incubating or rearing habitats for Arctic grayling.
Although Arctic grayling populations may occur in the impoundments near
tributary mouths,the Power Authority assumes for planning purposes that all
grayl i ng habi tat inundated by the impoundments wi 11 be lost.Ant ici pated
impacts to grayling habitats are considered unavoidable,as the inundation of
tri butary habi tats by the impoundments is a necessary part of the project
design and operation (APA 1985d).As a result of the expected loss of
grayling habitats and anticipated reduction in populations,the Arctic
grayl ing is selected as the primary evaluation species in the impoundment
zones.It is the Power Authority's goal to provide compensation for these
losses by means that are mutually agreeable with resource managers.
The construction of the Devil Canyon dam (RM 152)will prevent chinook salmon
from migrating upstream of Devil Canyon.Chinook salmon have a high
46
cClmmercial,subsistence and sport value and are numerous in the Susitna River
below Devil Canyon.Upstream of Devil Canyon they are less abundant,as high
vel oc"it ies of the Devi 1 Canyon rapids usually 1imit upstream migrations of
f'ish.Because of their low densities upstream of Devil Canyon,losses of
chinoclk salmon are not considered to be significant.Compensation for lost
chinook spawning habitat will be provided in one of two ways:(1)by
m'itigative flow releases for juvenile chinook salmon below Devil Canyon,or
(:~)by habitat improvements in the middle Susitna River as part of the
impoundment mitigation (See Section 6.2.2).
The Stage I and III Watana impoundments may reduce the recruitment to burbot
populations inhabiting the reservoir area (Section 4.1.4 and 4.3.4).Burbot
dli!nsities in the upper Susitna River appear to be low and burbotare not
h'ighly sought by fishermen in this reach of the river.Therefore,no
mitigative measures are planned for burbot,as any reduction in burbot
populations in the impoundments is considered insignificant.
P1roject-rel ated impacts on Dolly Varden populations are expected to be
insigl1ificanL Few Dolly Varden are thought to occupy habitats within the
impoundment zone and they apparently are the dwarf stream-resident variety
that are rarely sought by fishermen.Therefore,mitigative measures are
considered unwarranted for Dolly Varden.
The only known occurrence of lake trout within the impoundment zone is in
Sally Lake.This population is not considered important in the overall
distribution of lake trout in the Susitna Basin.Project effects on lake
trout in Sally Lake are expected to be relatively small,as lake trout will
likely utilize the impoundments year-round.Therefore,no mitigative measures
are planned for lake trout.
47
-
-
-
-
6.0 PEVELOPMENT OF MITIGATION PLAN
6.1 APPROACH TO MITIGATION
The Alaska Power Authority's goal for the Susitna Hydroelectric Project
fisheries mitigation is to maintain the productivity of natural reproducing
populations (APA 1982).This is consistent with the mitigation goals of the
U.S.Fish and Wildlife Service (USFWS)and the Alaska Department of Fish and
Game (ADF&G)(APA 1982,ADF&G 1982a,USFWS 1981).When possible,maintaining
existing habitat quantity and quality is preferred.Where this is infeasible,
replacement habitat will be provided in sufficient quantity and quality to
support this productivity.If it is not possible to achieve this goal,the
Power Authority will provide compensation for the impact with means agreed
upon by the agencies.
The development and implementation of the fish mitigation plan follows a
logical step-by-step process.This process and its major components are
illustrated in Figure 6.The options proposed to mitigate for impacts of the
Susitna Hydroelectric Project are analyzed according to the hierarchical
scheme shown in Figure 7.
Mitigation options can be grouped into two broad categories based on different
approaches:
(1)Modifications to design,construction,or operation of the project;or
(2)Resource management strategies.
The first approach is project specific and emphasizes measures that avoid or
minimize adverse impacts according to the USFWS Mitigation Policy adopted by
the Power Authority (APA 1982)and coordinating agencies (ADF&G 1982a,USFWS
1981).These measures involve adjusting or adding project features during
design and planning so that mitigation becomes a built-in component of project
alcti ons.
48
-~
.....
Figure 6
[
c
IDENTIFICATION OF
IMPACTS AND GOALS OF PLAN
,
OPTION ANALYSIS
1
[,NEGOTIATION OF ACCEPTAB~E P~AN
...
IMPLEMENTATION OF PLAN
..
MONITORING OF PLAN
PLAN MODIFICATION
1
COMPLETION OF MITIGATION
TERMINATION OF MONITORING
Mitigation Plan Development and Implementation
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.
HARZA -EBASCO
SUSITNA JOINT VENTURE
____________--'-....L-...J
49
PARTIAL AVOIDANCE _~
PARTIAL RECTIFICATION~
PARTIAL COMPENSATION ~
AVOIDANCE
I
NO AVOIDANCE
1
MINIMIZATION
I
NO MINIMIZATION
1
RECTIFICATION
I
NO RECTIFICATION
1
REDUCTION
I
NO REDUCTION
.l
COMPENSATION
f
NO COMPENSATION
UNMlTIGATED/LOSS
RESIDUAL IMPACT
TOTAL AVOIDANCE
~---~SOME MINIMIZATION
~---~TOTAL RECTIFICATION
~---"""SOME REDUCTION
~---~~OTAL COMPENSATION
Figure 7 Option Analysis
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.
50
HARZA -EBASCO
SUSITNA JOINT VENTURE
,~
-
-!
-
When impacts cannot be avoided or minimized by the first approach,measures
that rectify,reduce or compensate wi 11 be impl emented.These types of
mitigation measures will require concurrence of resource management boards or
agenc"ies with jurisdiction over resources within the project area.
MH igat ion pl anni ng for the Susitna Hydroel ectri c Project has emphasized both
approaches.The sequence of option analysis from avoidance through compensa-
tion has been applied to each anticipated impact.If full mitigation can be
achieved at a high priority option,lower options may not be considered.
M1onitl[)ring of mitigation features is recognized as an integral part of the
mi t igat i on process.In some cases,mai ntenance will be a necessary part of
the mitigation plan.A general approach to monitoring has been developed by
the Power Authori ty and wi 11 be app1i ed to the fi shery resources and thei r
habitats.As fish mitigation plans are agreed upon by the Power Authority and
the r,esource agenc i es,moni tori ng plans wi 11 be spec i fi ed in greater detail.
6.2 jHISTORY OF IMPOUNDMENT MITIGATION PLANNING
The FERC license application (February 1983)for the two-stage,two-dam
Susitna Project recognized that the loss of clearwater tributary habitat in
the impoundment zones would be a significant project impact on Arctic grayling
popul.ations in the upper Susitna River (APA 1983b).The proposed mitigation
included the following compensation to provide for lost grayl ing habitat in
the impoundment zones:(1)fund research C?n the hatchery propagat i on of
Arcti,c grayling,(2)expand or build a hatchery to propagate Arctic grayling,
(3)stock Arctic grayling fingerling in suitable barren lakes within the
project area,and (4)if Arctic grayling propagation·proved to be technically
infeasible,expand a rainbow trout hatchery and stock rainbow trout in the
Devil Canyon reservoir.Stocking Arctic grayling in barren lakes within the
project area was proposed as the primary means of compensation because of the
desirability of in-kind,in-basin compensatfon.
Resource agencies comments on this proposed mitigation plan were generally
unfavorable and concluded that hatchery propagation of Arctic grayling must be
judged as speculative (ADF&G 1983c,USFWS-1983).The agencies suggested that
51
-i
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m"itigation measures should have documented successes in Alaska if possible
and,if mitigation measures are unproven,a demonstration of their
effectiveness in the project area should be undertaken.
In the Fish Mitigation Plan (WCC 1984)options were evaluated that would
mitigate impacts resulting from the project.The proposed mitigation for
h,abi tat losses in the impoundment zones was the expans i on of a rainbow trout
hatchery and the stocking of rainbow trout fingerling in out-of-basin lakes as
the primary compensation.This was proposed because of the high probabil ity
for success.Hatchery propagation of rainbow trout in Alaska is a documented
success and rainbow trout are highly sought by sport fishermen.The proposal
of stocking Devil Canyon reservoir with rainbow trout was dropped,due to
concern expressed about the expected low productivity and relatively high
turbidity levels in the Devil Canyon reservoir.The propagation and stocking
of Arctic grayling were also proposed as an option for achieving compensation,
because of the desirability of in-kind replacement and progress in the
technology of rearing grayling in hatcheries.
The ADF&G responded that rainbow trout hatcheries and stocking programs were
already in place and that the department did not favor an expansion of this
program as mitigation for lost habitat in the impoundments (ADF&G 1984).
Instead,the ADF&G endorsed the acquisition of public access and the
development of site facilities for recreational fishing in the Susitna River
and its tri butaries below Devil Canyon.The enhancement of middl e Susitna
River salmon stocks by habitat improvements was also favored.A summary of
agency comments on impoundment mitigation is shown in Table 13.
As a result of agency comments on impoundment mitigation planning,this report
evaluates three options for providing compensation for the expected losses of
fish habitat in the impoundment zones:(1)acquiring public access to the
Susitna River and its tributaries below Devil Canyon,(2)habitat
modifications or improvements in the middle Susitna River that would enhance
important resident species or important sport species of salmon,and (3)the
expansion of an Arctic grayling hatchery,the hatchery propagation of grayling
and the stocking of grayling within and out-of-basin areas.The acquisition
of public access and habitat improvements'are the primary mitigation options
52
"....
Table 13.Agency comments on Impoundment Mitigation Planning.
Agency
USFWS
USFWS
ADF&G
Date
13 Jan 83
14 Jan 83
18 Dec 84
31 Dec 84
Reason for
Correspondence
Review of Draft
Exhibit E,FERC
License
Application
Review ·of Draft
Exhibit E,FERC
License
Application
Comments on Fish
Mitigation
Workshop of 4
Dec 84
Comments on Fish
Mitigation
Workshop of 4
Dec 84
Comments
Grayling propagation in experimental
stages.Compensation by stocking
grayling is speculative.
Mitigation measures should have proven
success in Alaska.Demonstration of
hatchery-rearing of Arctic grayling
needed.
The APA appears to be planning
impoundment mitigation with realistic
objectives in accord with project
mitigation policy.
ADF&G does not support the expansion
of the rainbow trout stocking program
and does not favor stocking of the
impoundment.ADF&G endorses the
acquisition of public access and
developing site facilities for
recreational 'fishing in the Susitna
River and its tributaries below Devil
Canyon.Also favors habitat improve-
ments for salmon in the middle Susitna
River (Talkeetna-to-Devil Canyon).
-
..-,
Source:ADF&G 1983c,1984;USFWS 1983,1984.
53
,-
-
Pll'oposed by the Power Authori ty.Hatchery propagat i on and stocki ng of Arctic
grayling is the least preferred option.
6.3 ~ITIGATION OPTIONS
6.3.1 Acquisition of Public Access
(a)J~ackground
Increases in population and tourism in Alaska have resulted in a high demand
for T'ecreational fishing.Recreational fishing is considered an important
factOlr in the total management of many of the state's fi sheri es (Mi 11 s 1984).
In southcentral Al aska,the high recreational use of fi sh resources in the
region is largely attributable to the accessibility of many lakes and rivers
by the road system,the close proximity of these areas to major population
centers and heal thy fi sh resources.The highest demand for recreat i ona1
fishing is largely concentrated in areas that are accessible by road,which in
some s ituat ions creates uneven use patterns of the resource and i ntens i fi es
pressures on resource managers to provide additional recreational
opportunities.
The State of Alaska,recognlzlng the need to rectify immediate recreational
use probl ems and pl an for future development and management of recreational
areas,has developed a recreation action plan for southcentral Alaska (ADNR
and ADF&G 1984).This plan emphasizes the need for the designation of
recreational areas,the acquisition of public access to currently utilized and
future recreational areas,and the development of site facilities at
recreational areas.
The Susitna River basin is a large recreational area,which is close to
populations in Anchorage and the Mat-Su Valley and contains abundant fish
resources.However,access to the lower 84 mi 1es of the Sus i tna Ri ver is
limited to one privately owned boat launch at Kashwitna Landing (RM 61)and to
some of the eastside tributaries along the Parks Highway.Thus,resource
managers have identified the need to acquire public access and develop site
/
54
-
facil'ities in the Susitna Basin to even out resource utilization and create
new fishing opportunities (ADNR and ADF&G 1984).
Five parcels of land in the Susitna Basin have been identified for acquisition
iln the recreation action plan (ADNR and ADF&G 1984).The five parcels are
listed in the order of priority in Table 14.The first two priorities,
Kashw'itna Landing and Little Willow Creek,would increase the accessibility of
the Susitna River.The others would improve access to lakes and tributaries
in the basin,or provide hiking trails.
Tlhe recreat i on act ion plan a1so recommends the deve 1opment of three
recre;at i ona 1 fac i1 it i es in the Sus i tna Bas in.The three fac il it i es
devellopment projects are listed in Table 14.All three developments would
ill1lprove access to the Susitna River by building roads,trails,or boat
1aunches.
Resou'rce managers have recommended that the southcentral recreation action
plan deserves timely implementation (ADNR and ADF&G 1984).However,it is
recognized that the plan is an ambitious one that may take years to fully
implement,particularly in view of the decl'ining capital budget of the State
of Alaska.Thus,the ADF&G (1984)has endorsed land acquisition and
facilities development for recreational fishing in theSusitna River as the
preferred measure of compensation for lost fish habitat and reductions in fish
popul ati ons resulti n9 from the impoundments of the proposed Susitna
Hydroelectric Project.
(b)$ite Selection
The selection of specific parcels of land and the development of recreational
facilities will require close coordination between the Power Authority and
resource agenci es.After the 1i cense to buil d the project has been granted,
potential land acquisitions and facilities development projects within the
Susitna Basin will be prioritized with input from resource managers.The
southcentral Alaska recreation action plan (ADNR and ADF&G 1984)and any
forthcoming planning documents on this subject will serve as the basis for
site selections.
55
I~
Table 14"Land acquisitions and facilities development projects currently proposed
by the State of Alaska in the Susitna River Basin.
Project Description
Estimated Costs
Annual
Capital Operating
Costs Costs
Land Acquisitions
Kashwitna Landing
Little Willow Creek
Neil Lake
Moose Creek
Nancy Lakes
Boat launch on Lower Susitna R.$500,000
Provide access from Parks Hwy.to $180,000
Susitna R.
Floatplane access to the Deshka R.$600,000
Road access for river use $200,000
Inholdings acquisition for trails $250,000
in Nancy lake Recreation Area
Facilities Development
Willow Creek State Major fishing area in lower Susitna $7,735,000 $212,500
Recreational Area River
Talkeetna Boat
!Launch
Campground/access/boat launch
at Talkeetna
Trail to fishing area near
Parks Hwy.
$173,000
$200,000
-
-
Source:ADNR and ADF&G 1984.
56
,....
-
-
-
-
Factors that will likely be considered during the selection process include:
1.identification of potential sites,
2.historic use levels of the sites,
3.benefits associated with land acquisitions or facilities
developments,
4.cost appraisals of lands or developments,
5.location of sites in the Susitna Basin,
6.timetable for acquisitions or developments,and
7.the probabi 1i ty of acqui ri ng or deve 1opi ng sites by convent i ona 1
funding sources.
After land parcels or facilities developments have been selected,the Power
Authority will take the necessary steps to complete the acquisition of
selected lands or the development of site facilities with the highest ranking.
This will occur within a time frame mutually agreed to by the Power Authority
and reviewing agencies.In the event that selected acquisitions or
developments are found to be infeasible the APA,with concurrence of the
agencies,will negotiate the acquisition or development of the next highest
priority.
(c)Costs
Since compensation for lost grayling habitat is the primary concern in
impoundment mitigation planning,the costs developed in the original FERC
license application to propagate and stock grayling can be used as a basis to
budget for land acquisitions or recreational facilities development projects
and habitat improvements (Section 6.3.2).These costs are presented in Table
15.
(d)Monitoring Studies
/lIfter'the acquisition of lands or the development of recreational facilities
is completed,it is assumed that resource agencies will manage and maintain
the lands and facilities.Therefore,monitoring studies are not planned for
these!measures./
(51 .
Table 15.Proposed fisheries mitigation for the impoun~ment zone with
estimated capital and annual operating costs •
Annual operating and
Mitigation Feature Capital costs maintenance costs
~.
Public Access Acquisition 650,000 N/A
Habitat Improvement 290,000 20,000
Total 940,000 20,000
1 Costs are based on primary mitigation options
SlourCl~:APA 1985d
~,if /tY~JJ{)f)..~.-,_.!.._,,-,-.,.-.-...
Z,O a'Vl..~
I'
58
j /.
.,".£,0 /{}..,r~!4d'J,,'"'.).'vi/c,'
-
6 ..3.2 Habitat Improvements
(il)!~ackground
TheA1laska Department of Fish and Game (1984),in review comments on the Fish
Witigcltion Plan (WCC 1984),has indicated that habitat improvements enhancing
salmon stocks in the middle Susitna River (Talkeetna to Devil Canyon)should
be considered as compensation for lost fish habitat in the impoundment zones.
Since the lost habitat primarily affects important sport species in the upper
Susitna Basin,mitigation planning has focused on the enhancement
possibilities for important sport species of salmon in the middle Susitna
River::chinook and coho.Additionally,habitat improvements enhancing
important resident sport fish (rainbow trout and Arctic grayl ing)in the
middle Susitna River are also considered.
(b)Site Selection
MIDst mitigation planning and associated field data collection in the middle
Susitlna River have concentrated on mitigating for potential losses of chum
salmolrl spawning habitat in sloughs and side channels.If slough excavations
are needed to maintain chum salmon spawning habitat,additional modifications
can be done to enhance coho rearing and possibly juvenile rainbow trout and
Arctic grayling habitat.For example,in spawning channels constructed in the
Chilkat River near Haines,Alaska,rip-rap added to the sloping sides of the
channel to stabilize the banks also provided habitat for juvenile coho salmon
(B.Bachen,NSERA,pers comm.,1985).When specific mitigation measures are
proposed for downstream impacts,this type of habitat improvement can be
incorporated.
The removal of fish passage barriers in the middle reach of the Susitna River
has been considered as a means of expanding fish habitat.In Fourth of July
Creek (RM 131),two waterfalls at tributary river mile 1.8 block the upstream
passage of fi sh.It has been suggested that the removal of these barri ers
could enhance the rainbow trout population in Fourth of July Creek by
providing additional spawning habitat upstream of the falls (Schmidt et al.
1984).However,a more recent st~dy has/revealed that rainbow trout already
59
-
-
occur upstream of the fall sin 1akes connected to tri butari es of Fourth of
July ,and likely provide recruitment to the rainbow trout population below the
f,alls (Sundet and Pechek 1985).Additionally,it appears that rearing habitat
may be 1 imi ted upstream of the fall s,as the rainbow trout samp1 ed were
smallli!r than·fish of the same age in other tributaries of the middle Susitna
River (Sundet and Pechek 1985).Because of these factors,it is unlikely that
p'roviding upstream fish passage beyond the falls would enhance the rainbow
trout population in Fourth of July Creek.
There may be a potential to expand fish habitat in the middle Susitna River by
r,emoving fish barriers in Portage Creek or Gash Creek (ADF&G 1985).In
Portage Creek,two lakes appear to have barriers to upstream migrating fish at
their outlets.One of these lakes has a population of rainbow trout,the
other lake has not been sampled (Sundet and Pechek 1985).In Gash Creek
upstream passage is partially blocked by a culvert at the Alaska railroad
crossing.Upstream passage into a small lake at the headwaters of Gash Creek
is blocked by a beaver dam at the lake outlet.Although these two creeks may
have some potential for expanding fish habitat,overall it appears that the
removal of barriers to upstream migration will not significantly expand fish
habitat in the middle Susitna River.At present,the opportunities to enhance
resident populations through habitat improvement in the middle Susitna River
appear limited,however the Power Authority will continue to evaluate this
mitigation option.
(c)Costs
The c:osts associ ated wi th habi tat improvements as a mi t i gat i on measure for
impoundment area habitat losses are presented in Table 15.The allocation of
funds for impoundment mitigation features emphasizes the acquisition of public
access due to the apparent limited potential for habitat improvements.
(d)Monitoring Studies
If habitat improvements are chosen in the middle Susitna River to provide
compensation for lost fish habitat in the impoundment area,monitoring studies
w'i 11 be conducted to evaluate the success 'of the improvements.It is assumed
60
that monitoring efforts required for h'abitat improvements will be coordinated
with the monitoring for other mitigation measures in the middle Susitna River~
The annual cost of monitoring habitat improvements is presented in Table 15.
Mon itori ng stud i es and budget detail s for impoundment area fi sh mit igat ion
w'j 11 be further refi ned when spec i fi c habi tat improvement sites are selected.
6.3.3 Hatchery Propagation of Arctic Grayling
(a)j3ackground
Habitiit alterations resulting from the impoundments will primarily affect
Alrcti4:grayling populations in the upperSusitna River.When possible,it is
dlesiriible to compensate anticipated reductions of fish populations with
i In-ki nd replacement (USFWS 1981).The hatchery propagat i on and stocki ng of
Arctil:grayling provides in-kind compensation.However,since Arctic grayling
propa~~ati on technology is st ill in the deve 1opmenta1 stages and cannot be
fully relied on to provide compensation,the ADF&G (1984)has recommended
other options to provi de compensation for lost fi sh habi tat in the
impoundments.At present,the hatchery propagation and stocking of Arctic
grayling is the least preferred of the three options evaluated.
(b)Hatchery Propagation Technology
Arctic grayling artificial propagation is being conducted by the Fisheries
Rehabilitation Enhancement and Development (FRED)Division of ADF&G at Clear,
Alaska.Arctic grayl i ng broodstock have not yet been developed at Cl ear
Hatchery,so eggs are taken from wild fish and transported to the hatchery for
incubat~on.In 1984,over 2.0 million eggs were taken from grayling in three
lakes~Moose,Jack and Tahneta (Parks et al.1985).Using wild fish as an egg
source is not a fail-safe method,but in the absence of an established
hatchery-production brood stock program it is the best method available.
Eggs are incubated at Clear Hatchery using Heath Techna stacks.Water
temperatures are varied between 3.5 and 10.50 C to manipulate the emergence
timing of fry.In 1984,egg-to-fry survival was over 70 percent (Parks et al.
1985).
61
.-
.-
....
I
-
Grayl i ng are usually stocked as sac-fry.Because the stocki ng success of
sac-fry is generally low,efforts are underway to develop fingerling
production at Clear Hatchery (Parks et al.1985).In 1984,about 125,000
grayling were reared to fingerling size (2.0 gram weight).The average
survival rate of 560,000 sac-fry to the fingerling stage using nine different
diets was approximately 22 percent.Fish raised on diets of krill,liver,and
OMP (Oregon Moist Pellet)mash exceeded the average survival rate.Survival
rates were 72 percent with the krill diet,66 percent with the 1iver diet and
52 percent with OMP mash diet.Fish raised on the other six diets had
survival rates of 30 percent or less (Parks et al.1985).Although fingerling
production is still in the developmental stages,the results of experimental
efforts in 1984 indicate large-scale fingerling production of Arctic grayling
is feasible.
(c)Stocking Program Site Selection
If a grayl ing stocking program is found to be feasible and is selected as a
mitigation measure,stocking sites will be chosen in close consultation with
resource managers.Sites will be evaluated within the Susitna Basin and
outside the Susitna Basin.
The potential sites for stocking grayling within the project area appear to be
limited.,Most lakes and streams in the upper Susitna Basin contain
unexploited fish populations that are currently utilizing most of the
available fish habitat,as indicated by the high densities.of fish (ADF&G
1981a,1983a,Sautner and Stratton 1984).Barren lakes or streams with
barri ers to fi sh movements could be stocked.These sites will need to be
evaluated for their capacity to successfully overwinter fish and thelr
accessibility to anglers.
It may be possible to plant grayling in borrow pits resulting from the
construction of the project access roads and dams.However,unless the
proposed side-borrow technique for building access roads is inadequate,no
gravel pits will be excavated duri ng access road construction.The major
gravel pit used during construction of the Watana dam at Borrow Site E will be
62
,....
,-
..,..
....
.....
I
contoured and connected to the Susitna River,allowing fish utilization of
this area without the need for stocking (Entrix,Inc.1985).
Stocking grayling in out-of-basin areas could supplement eXisting stocking
programs or create new fishing opportunities.Site selection would be done in
close consultation with the Sport Fish Division of ADF&G.In 1984,65 sites
throughout Alaska were stocked with grayling (Parks et al.1985).Thus,an
active stocking program of Arctic grayling already exists,when fry and
fingerling are available from the hatchery.
(d)Costs
The costs associated with implementing a grayl ing stocking program were
developed in the original FERC license application (APA 1983b).The cost of
expanding an existing hatchery facility is approximately $750,000 in 1982
dollars,while the operating and maintenance costs are an estimated $110,000
per year (APA 1983b).
(e)Monitoring Studies
Monitoring the success of a stocking program is an integral part of this
mitigation option.The scope and extent of monitoring will be developed when
specific mitigation options and sites are chosen.
/
63
LITERATURE CITED
-
....
7.0 LITERATURE CITED
Acres American,Inc.1982.Susitna Hydroelectric Project,Feasibility Report.
Final Draft.Prepared for the Alaska Power Authority.Anchorage,
Alaska.
Alaska Department of Fish and Game.1981a.Susitna Hydro Aquatic Studies -
Phase I Report:Resident Fish Investigations on the upper Susitna River.
Prepared for Acres American,Inc.Buffalo,NY.137 pp.
Alaska Department of Fish and Game.1981b.Susitna Hydro Aquatic Studies -
Phase I Final Draft Report:Adult anadromous fisheries project.
Prepared for Acres American,Inc.Buffalo,NY.
Alaska Department of Fish and Game.1981c.Susitna Hydro Aquatic Studies -
Phase I Final Draft Report:Juvenile anadromous fish ~tudy on the lower
Susitna River.Prepared for Acres American,Inc.Buffalo,NY.121 pp.
Alaska Department of Fish and Game.1982a.Statement of Policy on Mitigation
of Fish and Game Habitat Disruptions.Juneau .
Alaska Department of Fish and Game.1982b.Susitna Hydro Aquatic Studies -
Phase II Final Data Report:Volume 2.Adult anadromous fish studies.
Anchorage,AK.239 pp.
Alaska Department of Fish and Game.1983a.
Phase II Basic Data Report.Volume 5:
studies,1982.Anchorage,AK.150 pp.
Susitna Hydro Aquatic Studies -
Upper Susitna River impoundment
.-
Al aska Department of Fi sh and Game.1983b.
Phase II Basic Data Report.Volume 3:
fish studies below Devil Canyon,1982.
Susitna
Resident
177 pp.
Hydro Aquatic Studies.
and juvenile anadromous
Alaska Department of Fish and Game.1983c.Review Comments -Draft Exhibit E
-Susitna Hydroelectric Project.Prepared for Alaska Power Authority.
64
Alaska Department of Fish and Game.1984.Letter from D.W.Collinsworth to
L.D.Crawford of APA.Comments on Susitna Hydroelectric Project -Fish
Mitigation Plan and Workshop.December 31.
Alaska Department of Fish and Game.1985.FY 1986 Draft Plan of Study.
Submitted to the Alaska Power Authority.April 15.
Alaska Department of Natural Resources and Alaska Department of Fish and Game.
1984.Southcentral Recreation Action Plan.Presented to Governor Bill
Sheffield .
.-
Alaska Power Authority.1982.Susitna Hydroelectric Project:Fish and
Wildlife Mitigation Policy.Alaska Power Authority.Anchorage,AK.
Alaska Power Authority.1983a.Application
Susitna Hydroelectric Project,before
Commission.Vol.SA.Exhibit E,Chaps.
for 1 icense
the Federal
1 and 2.
for major project,
Energy Regulatory
Alaska Power Authority.1983b.Application for license for major project,
Susitna Hydroelectric Project,before the Federal Energy Regulatory
Commission.Vol.6A.Exhibit E,Chap.3.
Alaska Power Authority.1985a.Board of Directors Meeting.Supplemental
Information on Licensing Review and Consideration of Proposed Staging of
Construction of the Susitna Hydroelectric Project ..May 3.
-Alaska Power Authority.1985b.Exhibit A.FERC License Application Amendment.
Anchorage,Alaska.
Alaska Power Authority.1985c.Exhibit E.Chapter 2.FERC License Application
Amendment.Anchorage,Alaska.
Alaska Power Authority.1985d.Exhibit E.Chapter 3.FERC License
Application Amendment.Anchorage,Alaska.
Alaska Power Authority.1985e.October 2 Board Meeting .
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....
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f"""
I
I
i ~
....
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68
Susitna