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CORDOVA POWER SUPPLY
INTERIM FEASIBILITY
ASSESSMENT
TECHNICAL DATA
JUNE 1982
. A Stone & Webster Engineering Corporation J
L....-_ ALASKA I·OlVI~R A(T1~11('RI1'Y_---'
CORDOVA POWER SUPPLY
INTERIM FEASIBILITY ANALYSIS
SUPPLEMENTARY VOLUME -TECHNICAL DATA
TABLE OF CONTENTS
SUPPLEMENTARY TECHNICAL REPORTS
CORDOVA -VALDEZ DC TRANSMISSION TIE LINE FEASIBILITY REPORT
PREPARED BY ALCAT ENGINEERING, May 1, 1982
METEOROLOGICAL EVALUATION OF THE PROPOSED ALASKA TRANSMISSION LINE ROUTES
PREPARED BY METEOROLOGY RESEARCH, INC., January 25, 1982.
METEOROLOGICAL EVALUATION OF THE PROPOSED PALMER TO GLENNALLEN TRANSMISSION
LINE ROUTE
PREPARED BY METEOROLOGY RESEARCH, INC., April 23, 1982
SOUTHCENTRAL HYDROPOWER CORDOVA INTERIM, CORDOVA, ALASKA
DRAFT COORDINATION ACT REPORT SUBMITTED TO ALASKA DISTRICT, U.S. ARMY,
CORPS OF ENGINEERS, ANCHORAGE, ALASKA
PREPARED BY WESTERN ALASKA ECOLOGICAL SERVICES FIELD OFFICE, U. S. FISH AND
WILDLIFE SERVICE, ANCHORAGE, ALASKA, November 1980
VALDEZ INTERIM SOUTHCENTRAL RAILBELT STUDY, ALLISON LAKE HYDROPOWER
PROJECT, ALASKA
FINAL FISH AND WILDLIFE COORDINATION ACT REPORT SUBMITTED TO ALASKA
DISTRICT, U.S. ARMY, CORPS OF ENGINEERS, ANCHORAGE, ALASKA
PREPARED BY WESTERN ALASKA ECOLOGICAL SERVICES FIELD OFFICE, U.S. FISH AND
WILDLIFE SERVICE, ANCHORAGE, ALASKA, May 1980
Southcentral Hydropower
Cordova Interim
Cordova, Alaska
Draft
Coordination Act Report
Submitted to Alaska District
U.S. Army Corps of Engineers
Anchorage, Alaska
Prepared by: Paul Hanna, Project Biologist
Approved by: Robert Bowker, Field Supervisor
Western Alaska Ecological Services Field Office
U.S. Fish and Wildlife Service
Anchorage, Alaska
November 1980
Table of Contents
Page
I'ntroduction ••••••••••••••••••••••••••••••••••••••••••• " • • •• 7
Project Description ..................... ' ..... " ............................. 7
Crater l.a.ke ••••••••••••••••• ,................................ 7
Humpback Creek ................................................. 7
Power Creek ••••••••••••••••••••••••••••••••••••••••••••••• 7
Description of Resources •••••••••••••••••••••••••••••••••••• 10
Cordova Vicinity •••••••••••••••••••••••••••••••••••••••••• lO
Crater' Lake ••••••••••••••••••••••••••••••••••••••••••••••• ll
Iiump:back Creek ............................................. 14
Power· Creek ••••••••••••••••••••••••••••••••••••••••••••••• 20
Major Potential Impacts ........... '., •••••••••••••••••••••••••• 46
era ter I..a.ke ••••••••••••••••••• , ••• ' •••• ' ••••••••••••••••••••• 46
Huttrpback Creek •••• , ........................................... 47
Power Creek •.•••••••••••••••••••••••••••••••••••••• -.... ., ..... 49
Discus si.on ................................................. A ••• 53
Crater Lake •••• ·a •••••••••••••••••• -................ a, ••••••••• 53
Humpback Creek •••••••••••••••••••••••••••••••••••••••••••• 54
Power Creek. •••••••••••••••••••••••••• " ••••• ., ................ 54
Recommendations •••••••••••••••••••••••••••••••••••••••••• ~ •• 56
Crater Lake ••••• e-........................................... 56
H~back Creek •••••••••••••••••••••••••••••••••••••••••••• 56
Power Creek ••••••••••••••••••••••••••••••••••••••••••••••• 57
Literature Cited •••••••••••••••••••••••••••••••••••••••••••• 58
Appendices ••••••••••••••••••••••••••••••••••••••• ~ •••••••••• 59
f:1\.:..,. 7
...
List of Tables
Page
Table 1. Pink salmon escapement counts, Humpback Creek,
1960-79 .•.••.•••....•...•.•...•••..•..•.•....•••.. 17
Table 2. Power Creek water temperatures from ~~rch 27 to
September 17 1980 •••••••••••••••••••••••••••.••••• 24
Table 3. Spawning depth -water velocity criteria for
salmonid fishes found in Power Creek •••••••••••••• 28
Table 4. Summary of trapping results on Power Creek using
minnow traps, March 27 and 28, 1980 ••••••••••••••• 35
Table 5. Summary of trapping results on Power Creek using
minnow traps, April 18-20, 1980 ••••••••••••••••••• 35
Table 6. Sucmary of trapping results on Power Creek using
minnow traps, June 4-7, 1980 •••••••••••••••••••••• 36
Table 7. Summary of trapping results on Power Creek using
fyke nets, June 4-7, 1980 ••••••.••••••••••••••••••• 37
Table 8. Summary of fish captured on Power Creek using
minnow traps and fyke nets, June 4-7, 1980 •••••••• 37
Table 9. Summary of fish captured on Power Creek during
spring and summer, 1980 ••••••••••••••••••••••••••• 38
Table 10. Percent of tiI!le streamflow exceeds minimum
allowable flow for turbine operation on Power
Creek (run-of-the-river) •••••••••••••••••••••••••• 51
f}
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
~ -.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
List of Figures
Page
Cordova location and vicinity map •••••••••••••••• 8
Potential hydropower sites near Cordova •••••••••• 9
Crater Lake with Eyak Mountain in the background -
June 6, 1980 •••••••••••.•••••••••••••••.•••••••••• 12
Distribution of mountain goats north and.
east' of Cordova •.•••••••••••••••••••.••• e· •••••••• 13
Humpback Creek looking upstream towards the
head of the drainage ••••••••••••••••••••••••••••• 15
Humpback Creek delta jutting out into Orca
Inlet ...•.••..•.•.....••.•.•..•..•...•...• -.....•.. 16
Humpback Creek delta above the normal high
tide line •••••••••••••••••••••••••••••••••••••••• 16
Uppermost man-made dam on Humpback Creek, June
6, 1980 •••••••••••••••••••••••••••••••••••••••••• 18
Log crib dam on Humpback Creek constructed for
power generation in the early 1900's. June 6,
1980 ••••••••••••••••••••••••••••••••••••••••••••• 18
Upper end of the Power Creek drainage •••••••••••• 21
Ohman Falls on Power Creek ••••••••••• , ••••••••••• 21
Power Creek delta looking west towards Eyak
Lake ••••••••••••••••••••••••••••••••••••••••••••• 22
Power Creek prior to entering steep canyon area.
Massive landslide responsible for creating
Ohman Falls enters from the right •••••••••••••••• 22
Potential salmon spawning habitat in the mainstem
of Power Creek, April 19, 1980. Average
daily stream flow 61 cfs ••••••••••••••••••••••••• 29
Potential spawning area depicted in Figure 13,
June 5, 1980. Average daily streamflow
630 cfs ............•.. e· •••••••••••••••••••••••••• 29
Outlet of only significant tributary to Power
Creek within the project area, June 5, 1980 •••••• 31
Photo identical to Figure 15 taken on }~rch
27, 1980 ••••••••••••••••••••••••••••••••••••••••• 31
Saleen spawning area, tributary to Power
Creek •••••••••••••••••••••••••••••••••••••••••••• 32
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Salmon spawning area. tributary to Power
Creek •..•.•.•...• e-e •••••••••••••••••••••••••••••• 32
Salmon spawning area. tributary to Power
Creek.-••••••••••••••••••••••••••••••••••• e-••••••• 33
Evidence of spawning salmon scattered along the
bank by bears the previous year •••••••••••••••••• 33
Length -frequency graph of Dolly Varden trapped
on Power Creek June 4-7. 1980 •••••••••••••••••••• 42
Extensive wetland area above Ohman Falls created
by groundwater flow and beaver dams •••••••••••••• 44
Appendices
Appendix I. Scientific naoes of .vegetation~ maomals~ birds
fish, and marine invertebrates appearing in
Page
the text •...•.........••............................. 59
Appendix II. Drawings of Pover Creek depicting the major
physical and biological characteristices from
the USGS gauging station to 0.3 miles above
the end of the Power Creek road ••••••••••••••••••••• 62
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INTRODUCTION
Cordova is located on the southcentral coast of Alask.a.~ appro:dJ:Jately 160
miles southeast of Anchorage (Figure 1). The town is situated on Orca
Inlet near the eastern entrance to Prince Will1c'l1n Sound. The population
of the area is s1!lall and at present has a fishing and fish-processing
based economy. Due to the great distance from readily available sources
of power, Cordova has developed its own means of producing electricity -
diesel generation. Currently Cordova is faced with the problems of
burning an lL"tpenaive, non-renewable fossil fuel as its sole source of
power.
The purpose of the Corps of Engineers (CE) investigation is to eValuate
potential hydroelectric power sites near Cordova to see if the town can
ult1t:zately replace all or some of i'tS diesel generators. A Reconnaissance
Report subt:J1.tted to the CE in September 1979 by CIi 2H Hill concluded that
hydropower development in the immediate area of Cordova was a feasible
alternative to diesel generation. Three areas were identified for further
s~dy: Crater Lake, HUmpback Creek, and Power Creek. Biological investi-
gations associated with the project areas were conducted by U.S. Fish and
t·1Udli£e Service (FWS) and CE biologists on Harch 27 and 28. April 18-20.
June 4-8, and October 2, 1980.
PROJECT DESCRIPTION
The three potential sites identified include a lake tap (Crater Lake) and
two run-of-the-river developments (llumpback Creek and Power Creek). At
this time, design plans are not available. Due to low flows and ice
problems, hydroelectric generation for Crater Lake and Humpback Creek
would only occur from May through October. Power Creek has the potential
for year round generation •.
Crater Lake -This site is located approximately 2.75 miles northeast of
Cordova (Figure 2). It would affect lands belonging to the Eyak ~~tive
Corporation and state-owned land withdrawn by Cordova. Development would
consist of a lake tap utilizing a concrete diversion da~ 5 feet hibh and
15 feet long and a 4~80o-foot penstoek of la-inch pipe leading to a
powerhouse on Or~a Inlet. The rated ~apacity of this project would be
458 Kilowatts (Kw) and would not caet Cordova's present peak demand of
3,150 Kw.
Humpback Creek -This site is located 6 miles northeast of Cordova
(Figure 2). It would affect lands belonging to the Eyak Native
Corporation and the Chugach National Forest. Development would consist
J1 of a run-of-the-river project utilizing a 'concrete diversion dam 5 feet
high and 30 feet long, a 6,625-foot flume and a 70o-foot penstock of
30-inch pipe leading to a poverhous8 approximately 0.75 ~iles from Orca
Inlet. 'l'he rated capacity of this project would be 1,010 Kit and ~rollld
not meet Cordova's present peak decand either.
Pover Creek -The project area is located 3 miles northeast of Cordova
(Figure 2). It would affect lands belonging to the Chugach !lational
Forest. The Reconnaissance Report indicates that this site is the ODst
feasible for power generation (C!!ZH IIil!, 1979). Development ~Jould
consist of a run-of-the-river project utilizing a lO-foot concrete
diversion d~ near mile 3.2 on Paver Creek with a tunnel pipeline and
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~ penstock leading to a powerhouse approximately 0.5 to 0.75 miles froe
£yak Lake. The ~ated capacity of the project would be 5.000 Kw and
essentially ~et Cordova's demands throu~h the year leOO.
UESCRIPTICN OF RESOURCES
Cordova Vicinity -The fish and wildlife resources present in the vicinity
of Corcova are ~epresentative of aquatic species found in Prince William
Sound and terrestrial species associated ~th the coastal ~estern hemlock-
Sitka spruce forest. S~ient1fie names of vegetation, tnal!m!als, birds,
fish, and oarine invertebrates appearing in the text are listed in Appendix
I.
The Chugach Mountains surround the community, confining it to a narrow
band along the edge of Orca Inlet. Rugged east trending ridges and
massive lCOuntain peaks are separated by a network of narrow valleys and
passes. The area has been heavily glaciated and vast icefie1ds snd
glaciers persist throughout. The coast is cut by many fiords and the
ridges may extend into the sea as islands. Stre3mG are short, swift, and
t"!oatly glacial. The cliJ3ate is controlled largely by the mountain barriers
and the Gulf of Alaska. Annual precipitation increases gracually from
west to east. lleavy snowfall and frequent rain push avera~e precipitation
levels to over 100 inches a year in coastal areas. The moderate climate
and hign preCipitation produces forests of Sitka spruce and western
hemlock. Dense alder patches occur near t~erl1ne and on 3teep exposures.
Timberline is rather low, often around 1,500 feet, but sooet1mes as lov
as the shoreline. A heavy undergrowth of devilsclub. ferns, aoases.
grasses, and brush is cammon.
Cordova lies just west of the Copper River Delta. ~is area produces
more ducks per square mile than tlOst known habitats in Alas~. It is
also an important stop for migrating geese, swans, cranes, and a ~iad
of shorebirds.
Several species of ma tine mar:=als occur wi thin the Cordova area. F~wever t
only harbor seals, sea otters, and an occasional Dall porpoise are documented
as utilizing nearshore waters.
Typical terrestrial oarma1s representee around Cordova include, but are
not limited to the follow1n~: Sitka black-tailed deer. brown bear. black
bear, oountain goat, porcupine, aarten, river otter, short-tailed weasel,
mink, beaver, and red squirrel.
~orthern bald eagles are c~n residents. !he entire Cordova area
contains a high density nesting population. Eagles nest in spruce or
hemlock trees at or near the water l s edge. Concentrations are found on
sa1=on spawning 8trea~ during the sucmer and fall.
Local waters are lucrative seafood-9roducing areas noted for fish and
shellfish. The anadro~us fish populations are dominated by five s?ecies
of Pacific salmon. Sa1non used for both commercial and recreational
purposes throu~hout the re~ion include pink, sockeye. C1Hll:1, coho, anrl
chinook. Other fish in the Cordova region of econo~ic value ~re herring,
hali~utt and flouncer. Dungeness, king. anc tancer crabs as well as
scallops and shrimp are found within the region. Razor, butter, horse,
and surf clams as well as cockles are harvested locally; hoycver, only
Based on the best information currently available, no threatened or
endangered species as listed by the U.S. Department of the Interior
(1979) for which the FWS has responsibility are known to occur in the
Cordova area. Protection of threatened or endangered I:lSrine cammals is
the· responsibility of the National Harine Fisheries Service (UHFS). The
CE may wish to contact the tniFS to deternine the presence of these species
near Cordova.
Crater Lake -Crater Lake is a clear, alpine lake situated in steep,
mountainous terrain between Orca Inlet and Eyak Lake (Figure 3). It has
a surface area of approximately 25 acres, a maximum depth of 61 feet, and
drains about 0.3 square miles. The lake lies at approximately 1,600 feet
elevation aDd is accessible by trail fram the Eyak Lake road. The P~con
naissance Report (CH 2M Hill, 1979) indicates that Crater Lake has no
natural outlet. HoWever, on June 6, 1980, water was observed spilling
from the lake. Presumably the flow is intermittent and the result of
snowmelt.
Vegetation.
The vegetation around Crater Lake is characteristic of alpine tundra.
Much of this type consists of barren rocks, but interspersed between the
bare rocks and rubble are many mat forming herbs, such as moss campion
and mountain avens. Comocn shrubs are the law growing cassiopes, nountain
heath, Labrador tea, and alpine azalea.
~ Fish
According to Hike McCurdy (1979),. a fishery biologist with the Alaska
DepartInent of Fish and Game (ADF&G), there were no native fish spedes in
Crater Lake prior to planting rainbow trout. The first stocking program
was initiated by the Fl'1S prior to Alaska statehood. Presently I the ADF&G
stocks the lake every 3 to 4 years Yith rainbows. The lake provides good
fishing for those local residents willing to hike uphill for several
miles. No creel census data are collected, so catch and gro~h rates are
unknown. It is believed that there is some limited natural reproduction
in the lake (McCurdy, 1979).
The outlet to Crater Lake flows northwest into Orca Inlet adjacent to the
Orca cannery. The ADF&G includes the Crater Lake outlet in their index
of pink salmon spawning streams but does not usually survey it during
annual escapement counts (Pirtle, 1977). Esc:ape~nt information is
l1r.lited to 1977 and 1979 when 200 fish were counted each year (Hike
McCurdy, ADF&G, pers. comm.). M1.ke !1cCurdy (pers. coma.) believes that
the small area where the lake outlet water enters Orca Inlet is only used
during odd years when pink salmon runs are norcally highest in Prince
William Sound. These fish -may be strays that have been forced to leave
overcrowded spawning areas nearby. The data presented in Table 1 tend to
support McCurdy's opinion. Table 1 contains escapement counts for pink
salmon in UtlI:lpback Creek. a short distance to the northeast. Both 1977
and 1979 were near record runs in that drainage.
Mammals
The ADF&G (1973) indicates that mountain goats are found in the steep
terrain northwest of Eyak Mountain. This area includes the small Crater
Lake basin (Figure 4). No estimate of the number of goats near Crater
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Figure 3. Crater Lake vith Ey~k Mount~in in the background -
June 6, 1980.
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population near Cordova has been reduced by hunting pressure due to the
proximity of town. Black bears are common and may be found in the Crater
Lake vicinity during the spring and summer. Sitka black-tailed deer are
also common during the summer and fall. On June 6, 1980. a short helicop-
ter flight was taken to view Crater Lake and the surrounding area (Figure
3). The lake was still 95 percent covered Yith snow and ice and no
landing was attempted. Mountain goat tracks were observed at the lake
near the eastern shoreline. Several sets of bear tracks were also observed
paralleling the ridge top.
Humpback·Creek -Humpback Creek is a short, steep, coastal stream typical
of the Prince William Sound area (Figure 5). It flows generally in a
westerly direction before entering Orca Inlet. Presently, there is no
road access. The watershed drains 2.6 square ~les, and the mean annual
flow is 25 cubic feet per second (cfs). The stream tends to freeze over
in the Winter and flows Virtually cease (CHi1 Hill, 1979). Humpback
creek provides considerable stream and intertidal spawning for pink
salmon on the lower 0.5 mlee of the drainage. A steep canyon area and a
series of old log dams precludes any further upstream movement of fish.
Vegetation
The primary vegetative type in the project area is a coastal western
hemlock-Sitka spruce forest. A narrow band of riparian species occupies
the Humpback Creek floodplain and marine flora typical of Prince ~illiam
Sound inhabit the terminus of the Rumpback Creek delta where it enters
Orca Inlet.
The western hemlock-Sitka spruce vegetation type is well represented.
Sitka spruce and western hemlock are the dominant oe~ers of the community.
Blueberries, devi1sclub, and several species of ericaceous shrubs make up
the unders tory. Because of the hieb rainfall and resul ting high humidi ty ,
mosses grow in great profusion on the ground, on fallen logs, and on the
lower branches of trees, as well as in forest openings.
Alders and willows occupy a narrav band along the streac channel pr~rily
near the mouth and above the canyon area. The creek has formed a small
gravel delta into Orca Inlet· (Figures 6 and 7). A portion of the delta
is being colonized by w111m~, grasses. and forbs. !he rest is barren.
The intertidal and subtidal areas off the delta appear to be quite pro-
ductive in te~ of marine flora. Roekweed, sea lettuce, wrack, and a
species of red algae are all abundant.
Fish -
Prince William Sound pink salmon stocks are particularly adapted to heavy
use of the inte~idal zone and Humpback Creek is no exception. Pink runs
typically display an even-odd year cyclicity and those stocks returning
to Humpback Creek tend to dominate on odd years (ADF&G, 1978a). Spawning
activity usually takes place fram late July to early August. Zscapeoent
counts conducted by the ADF&G are shown in Table 1.
Dolly Varden are found in lower Humpback Creek and are probably seasonally
attracted folloWing migrating pink sal~n. Sport fishing effort for
pinks and Dolly Varden is low (Pete Fridgen, ADF&G, Cordova, pers. cacm.).
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Figure 5. Humpback Creek looking upstream towards the head of
the drainage.
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ri)~lIrc 7. Humpback Creek deltn .1bovc the nonn'll high tide line.
BEsrCOPY':AVAlLABlE
1. Pink sall!lOR esen ecen"t counts Burn back Creek 1960-79.
Year !!o. Year ~ro.
"i%O 17390 T970 540
1961 16,010 1971 0,2:30
1962 7,200 1972 1,740
1963 9,860 1973 2,510
1964 3,560 1974 70
1965 1,200 1975 6,800
1966 310 1976 340
1961 420-1977 13,920
1968 550 1978 360
1969 4,730 1979 11,940
Source: Mike McCurdy, Alaska Department of Fish and Ga1!Ie, Cordova.
As previously mentioned, Humpback Creek flaws into a canyon appro~te17
1 Idle before it enters Orca Inlet. The canyon area is est1mated to be
between 0.5 to 0.75 miles lang. A series of three old log dacs, constructed
for power generation in the early 19OO's,-are a1tuatad approxl.wltely 0.25
miles apart beginning with where the creek first enters the canyon. !he
uppermoot dam is abeut 12 feet hi~ and i& situated where the creek
enters the canyon (Figure 8). Downstream about 0.25 edlC!s in the steepest
part of the canyon is another small dam about 10 to 12 feet high. .~out
0.25 o11e8 below the second daa is a large dam about 30 to 100 feet high
~~1gure 9). The big dam vas constructed of log cribbing and is slowly
~eteriorating. The ADP&Gest-i:2tes that 50,000 to 60,000 cubic yards
(cu. yds.) ot gravel is backed up ~ehind the strueture (Dick Nickerson,
ADF&G, Cordoya, pers. COCitl.). Duriug periods of high flOl~, gravel move-
cent over the big dam scours the lower creek channel decreasing the
survival of pink sal~n eggs.
The bi~ dam does not block sa1!!'1Oll oigration. Natural ve10dty barriers
occur dOW'llStrea:ca (Dick Uickerson, ADF&G, pers. co1!\o.). Hot.iever. if the
dam collapses, a tremendous amount of gravel vou1d be released and it
could take several years for the creek to flush all the gravel out of the
sys~em. Pink salcon eggs 1n ~~e lower end of the creek could be phYSically
damaged or buried limting the adult returns in !ucure years unt1.1 eh(!
lower end of the creek and the expanded delt~ area eventually stabilized.
Information on the occurrence of fish species in lluopback Craek above the
canyon area is not well docur~nted. The ADF&G states that fish are
probably absent (~cCurdy, 197~; Pete Fridgen, .\DF&G, pers. C~6).
Information provided by CH.,H U111 (1979) indicates that winter floY8 in
r:tumpbac:k Creek can get as lov as 2 efs and have been known to cease.
This makes the presence of a resident fish population highly unlikely.
On June 6, 1980, biolo~ists sacpled upper Hucpback Creek with minnow
traps and traditional sport fishing gear. !~ fish were captured. The
creek wus visually estimated to be flowing over 150 cis. Abundant 8trQ~~
~hank cover and a favorable pool-riffle ratio would make the upper stretcil
~a ,good Do 11y Varrlen strCaI:l if the winter flows did not Ci~3<lppear.
!-!amcals
Game species present in H~pback Creek include Sitka black-tailed deer.
brown bear, black bear, and MOuntain goat. ~·rountaln 30ats are usually
found above the timherline inhabitin the ~st rug~ec, inaccessible
~.'.: .. , ~ . JI
-l8-
Figure 8. Uppermosc man-made dam on Humpback Creek, June 6, 1980.
Figure 9. Log crih dam on Humpback Creek constructed for power
~""~ . :.~,,"
..
terrain. On June 6, no goats ~re observed in Humpback Creek during a
brief helicopter flight although suitable habitat is available (Figure
4). Reynolds (1930) estimates no mare than 20 goats are found in the
HUIlll'back Creek and Power Creek drainages at anyone tir.le. Goats use the
ridges overlooking Humpback Creek but their distribution varies greatly
by season. For purposes of this repor~, goat habitat in Hucpback Creek
is considered to be above the 500-foot contour line (Reynolds, 1980).
Black bear prefer forested habitat but are commonly seen foraging in open
meadows, tidal flats, brush fields, and alpine areas. Although no black
bear were seen during field investigations, Humpback Creek contains
excellent bear habitat. No critical denntng habitat for black bear has
been identified in the Humpback Creek drainage (ADF&G, 1973; Reynolds,
1980).
The ADF&G (1973) has documented that the salmon spawning area on lower
Humpback Creek contains seasonal concentrations of brown bear attracted
by the readily available food source. Clumps of brown bea.r hair were
found in the brush near the uppermost dam during field investigations on
June 6. Skeletal remains of pink saloon were found scattered on the bank
along the spawning reach. Biologists assumed that the fish reaains were
e~dence of brown bear use during the 1979 spawning season. t~ critical
denning habitat has been identified for brown bear in Hucpback Creek by
the ADF&G (1973). Reynolds (1980) estimates there are probably six brown
bear using the drainage.
Biologists encountered frequent evidence of Sitka black-tailed deer while
traversing the area from above the canyon to the delta. Deer tracks were
present in the sand along the creek above the canyon area and on the
delta. Numerous tracks and pellet groups were observed around scalI bogs
in the forest parallel to the creek. During the winter, deep snows force
deer down to the beach fringe throughout Prince t-lilliam Sound and when
populations are high, almost all these fringe areas can become critical
winter range. According to the ADF&G (1973), ~inland deer populations
in Prince William Sound are law and the eastern shore of Orca Inlet is
not considered to be an important vinter range. Even though direct
documentation is lacking, there is enough evidence of deer in Humpback
Creek to suggest that portions of the beach fringe on the eastern shore
of Orca Inlet, inclucing the Humpback Creek delta~ may be w1n~er range
for a few ani=als.
Birds
The Hum~back Creek delta provides feeding and nesting habitat for water-
fowl and shorebirds. ~Jenty Canada geese were observed on the delta on
June 6. Close investigation revealed that the geese were feeding on
succulent forba graving on the higher, dry areas of the delta where
permanent vegetation has become established. There was no evidence of
goose nesting. Several species of shorebirds nest on the delta although
not in great numbers. Species that were displaying protective behavior
indicating that they had nests nearby were: tuo pairs of spotted sand-
pipers, two pairs of semipalmated plovers, and one pair of black oyster-
catchers. Other birds observed in the area were glaucous-winged gulls,
mew gulls, black-legged kittiwakes, ravens, scoters, water pipits, harle-
quins, northern bald eagles, and savannah sparrows.
Northern bald ea les are fre uent visitors all alon 7 Orca Inlet.
Creek. During field investigations, biologists used a helicopter to
search the shores of Orca Inlet for several ~iles in either direction
from the mOuth of Humpback Creek and the lower 5 miles of Hucpback Creek
looking for bald eagle nests. None were located in spite of the fact
that a dozen adult birds were seen in the area.
Martne Biota
Besides the abundance of seaweed, the intertidal and subtidal habitats
off the delta appear to be productive in terms of marine organisms also.
Profuse amounts of barnacles cover all the exposed rocks and cobble.
MOllusk shells Windrowed by the surf are abundant -mussels, horse,
butter, and littleneck clams. and cockles. In addition, four sea otters
were observed feeding a short distance offshore.
Power Creek -Power Creek begins at a small glacier in the Chugach Moun-
tains at a point about 13 miles northeast of Cordova (Figure 10). It
flowa southwesterly for a distance of approximately 7 miles and enters
Eyak Lake near Mila 6 on the road leading from Cordova.
Miller (1951) investigated the geology of a proposed dam and reservoir on
Power Creek for the U.S. Geological Survey (USGS) and gave the following
description of the creek. In the upper 2.5 miles of the drainage, Power
Creek flows in a shallow eanyon cut in unconsolidated glacial and alluvial
deposits. For the next 2.5 miles the creek meanders from one side of the
valley to the other on a floodplain of unconsolidated mud, sand, and
gravel, fram 0.25 miles to 0.5 ~les in width. At a point about 2 miles
from Eyak Lake the creek sWings to the southeast side of the valley and
vertically drops 52 feet at Ohman Falls before continuing through a steep
walled canyon 200 to 450 feet deep cut in part in bedrock (Figure 11).
Less than Q.5 miles frca Eyak Lake the creek ecerges fram the canyon and
has formed a delta by filling in the northeast arm of the lake (Figure
12). The valley walls on both sides of the creek basin are steep~ riSing
abruptly from 2,000 to 4,000 feet.
The valley of Power Creek exhibits the U-shaped profile and flat floor
tha~ is typical of glacially-scoured and partially refilled valleys in
the region~ except for the lower 2 miles. In this stretch the even fall
of the valley is interrupted by a broad, fanlike ridge that extencs
nearly across the valley from the northwest side. This feature is respon-
sible for the creation of Ohman Falls and the steep canyon in the lo~er
portion of the drainage. Miller (1951) concluded that the fanlike ricge
was actually a massive landslide that came from the northwest valley wall
partially filling the glaciated valley and forcin3 Power Creek to cut
through a bedrock spur along the southeas~ side of the valley (Figure
13) •
That portion of Power Creek between Ohman Falls and the delta is charac-
terized by a relatively straight, stable channel. The only areas of
obvious erosion of the streambank are found just below Ohman Falls where
several active slides are contributing sedi~ent. The steep canyon area
is lined with bedrock and large boulders providing long-tero stability.
wnere the canyon widens out prior to entering the delta, the stream also
~dens. Sitka alder, other shrubs speCies, and conifers are well esta-
blished along this reach and even during extreoe high flows protect the
streambank from significant eroaion. The creek gently meanders and does
not contain numerous high water channels. Due to the nature of the
-21-
/-; ,
, , .. "-' . . . ' ... ; ". '. ',. -,"<.... • • ~. . .~" ."..'.. "~.. . ~ ..... ~
• .-..... • '.. ~-. ,.., -" ,J
• " " •. 1 ':--. ....".~ ... , ..... ,'. \ .. .' .... ".. -;..\;. ~ .< -r,.," -'. ,:.f .. , .'" " ,..:, -:. ""',.il -~ ~'~;""""'::"'''' '<',.. -: ~;;"¥-t; ",.,....¥, "" . i, ,i ;,:.:~ 'ii 1 ~~"'. ' , • ~ <¥. ,,~~ ~, ... ","' "~ -;''-'; r' . • ',-;-; .' # ..... 'h(gf ' ' I
,.1: .• ; ........ .,:'!.~~~.: ~~.,;.fj '.;).~;~">': ...... : !~"""~~\'~' ~~: ... '~. ,. ,,~. ~iN~ ,_. _ •. ~. '. ,', . ,---............ "'., '~:.--:I i "~. • ~ ~ 001' • (I , •. '1' ~ . ' .. ;;'.~L.~. • ..... -~ .... .'~ l (.. --. ~,.,.' , , , .,t .. '~~''';~. "~. \ ,. li" . • ' "j<'", •• '., ....... ". '.. "-, ' "'" , ........ , ." '" 'C"" ~'" ,~ "' •. -c. . " .. ' .' , .,' ~'" • ~ ., .'. '" .," .""""., ""0"... . ~'
. , ....
.. '.:. .~
....
" r "" -'. , "':';~~(' ''''', ~'~;?":~2~;',-:~, i',:; .. ' .t·" >.}, ·'i. drainage.
.~' ..
..... -
Powet" Creek end of the Figure 10. Upper
/ .. , •......... 11 ..
-22-
Figure 12. Power Creek tlclta looking 1oT'!5t towards Ey<1K Lake.
Figure 13. PO\""C'r Creek prior to entering steep canyon area.
~1;l~sivc l.,ndslide responsible for crcilting Ohman Falls enters
from the right.
11 cc.,. ,.._ r"l .& '\ I &" &" rI ...
~tra1ght, narrow canyon through which the creek flows, no sign1f1cant
I ·:J4ckwater poncs or sloughs are present; no islands or extensive deep
'pools have been formed; few log jams accumulate; and only one significant
tributary enters the main stream. Several seeps and small springs occur
but they do not appear to contribute significantly to the average annual
flow. The extent of groundwater discharge into the creek is unknown.
However, the CE plans to gather the data to esticate what the groundwater
contribution is (101:1 Murdock, CE, pers. comm.).
Power Creek bas a high runoff. but is unevenly distributed throughout the
year and is related directly to cl.il:latic conditions. During the winter
months when most of the precipitation comes as snow, the streamflow is
low. Due to the rugged topography of the basin, much of which is barren,
there is very little ground or bank storage (Johnson, 1949). There are
no lakes in the basin to provide natural storage. The snow accumulation
during the winter months, however, serves as a natural reservoir, releasing
the vater With the warmer temperatures of early summer (Johnson, 1949).
Daily variations in flow are also directly related to rainfall.
Because of the histOric interest shown in developing a hydro project on
Power Creek, the USGS installed a gauging station in 1947 to record
flow. The gauge has been maintained continuously from that date and
flow records are published annually in the USGS ~later Data Reports for
Alaska.
~Basel1ne data on water temperatures for Power Creek have not been
j1 adequately collected in the past. Consequently, the CE installed a
Peabody-Ryan thermograph on r.farch 27, 1980, about 100 yards upstream from
the, uses gauge. Table 2 contains daily highs and lows recorded froQ
March 27 to September 1.
~"".'."' .. "" "
:."..
Ve~etati.on
The major vegetative type in the project vicinity is a coastal western
hemlock-Sitka spruce forest. t'lestern hemlock and Sitka spruce are the
dominant species. Other tree species include a few balsam poplar. The
understory environment of the forest is composed primar1.1y of blueberry,
devilsc1ub, and bunchben:y. Copious growths of mosses and lichens cover
the forest floor, downed logs, and the lower branctles of trees. A thin
fringe of Sitka alder borders the edge of Power Creek and separates the
stream bank from the forest. Occasional black cottonwood trees occupy
the floodplain and the delta area where' Power Creek enters Eyak Lake.
Aquatic vegetation of the streambed is cocposed predominantly of a
filamentous brown algae. Mosses caver all the exposed rocks in the
stream and within the 11.m1ts of normal high water.
Fish -
Coho Salt:ion
The most important fishery resource in Power Creek is coho salmon. The
annual coho run into the Eyak Lake system is estimated at 8,000 to 12,000
fish n!cCurdy, 1979). Available information indicates that the great
1!lajor1ty of cohos entering Eyak Lake migrate up Power Creek and the run
C) Table 2. 1/
.. .~. Power Creek Water Temperatures-
From March 27 to September 1, 1980.
DATE HIGH LOW DATE HIGH LOW
Mar -4'lay
27 3.5 2.5 1 4.5 3.0
28 3.0 2.5 2 3.5 3.0
29 3.0 2.5 3 4.0 2.0
30 2.5 2.0 4 5.0 2.5
31 2.0 0.5 5 4.0 3.0
Apr 6 3.0 2.0
1 2.3 1.7 7 4.0 2.0
Z 2.0 1.5 8 4.5 3.0
3 3.0 1.5 9 5.0 2.5
4 2.5 2.0 10 3.5 3.0
5 3.8 2.3 11 5.0 3.0
6 4.5 2.2 12 5.5 2.5
7 3.0 2.2 13 5.5 3.5
8 3.4 2.1 14 4.0 3.5
9 4.0 2.1 1.5 5.0 3.0
10 3.0 2.5 16 4.0 3.0
11 3.3 3.3 17 3.0 3.0
12 3.3 0.5 1a 3.0 2.0
13 1.0 0.5 19 5.0 3.0
') 14 0.8 0.5 20 4.5 3.0
15 2.0 0.5 21 5.5 3.0
16 2.8 1.3 22 5.0 3.5
17 2.7 2.0 23 5.0 4.0
18 3.0 2.5 24 5.0 4.0
19 3.5 2.8 25 6.0 4.0
20 3.3 2.6 26 5.0 3.5
21 3.0 1.8 27 5.0 4.0
22 2.6 2.0 28 5.0 4.0
23 3.0 2.0 29 4.5 4.0
24 3 • .5 2.5 30 4.0 3.0
25 3.0 3.0 31 5.0 J.O
26 3.1 2.6 June
27 3.0 3.0 1 7.0 3.5
28 3.5 3.0 2 6.0 4.0
29 3.5 3.0 3~ 7.5 4.0 (half day)
30 3.5 3.0
1/ All tecperatures in degrees Centigrade
• Recording tape changed, new battery installed
0 Table 2 (continued).
DATE HII.R LOU DATE ITIGn LOW -June July
4 7.0 3.5 13 6.5 4.0
5 7.0 3.0 14 6.0 4.5
6 7.5 3.5 15 5.0 4.5
7 6.0 4.0 16 6.0 4.5
3 4.5 4.0 17 6.0 4.5
9 7.0 3.5 18 6.5 4.5
10 6.0 4.0 19 8.0 4.5
11 4.5 4.0 20 8.0 5.0
12 4.5 3.5 21 6.0 5.0
13 4.5 4.0 22 8.5 4.5
14 5.0 .. 3.5 23 7.0 5.0
15 5.0 4.0 24 6.0 5.0
16 6.0 4.0 25 5.5 5.0
17 4 • .5 4.0 26 5.5 5.0
18 4.5 3.5 27 6.0 5.0
19 5.0 4.0 28 b.O 5.0
2t) 4.0 4.0 29 6.0 5.0
21 5.5 3.5 30 5.0 S.Q
22 6.5 4.0 31 6.0 5.0
23 6.5 4.0 August
24 5 • .5 4.0 1 6.0 5.0
~ 25 5.0 4.0 2 7.0 5.0
~:-'. 26 5.5 4.0 3 6.0 5.0
27 5.0 4.0 4 3.0 5.0
23 5.0 4.0 5 8.5 5.0
29 5.0 3.0 6 3.5 5.0
30 6.5 4.0 7 a.o 5.0
July 8 6.0 5.5
1 7.5 4.0 ~ 6.0 5.5
2 8.0 4.0 10 6.0 5.5
3 5.5 4.0 11 7.0 5.0
4 8.0 4.0 12 ~.O 5.5
5 7.5 4.0 13 7.0 5.5
6 5.5 5.0 14 6.5 5.5
7 5.5 4.5 15 6.0 5.0
8 6.0 4.5 16 6.0 5.0
9 5.5 4.5 17 6.0 5.0
10 5.5 4.0 18 6.5 5.0
11 5.0 5.0 19 6.0 5.5
12 5.0 4.5 20 7.0 s.n
~""".'.' .. -'., .. . '
. /"'''~
f) Table 2 (continued).
DAT! ~IIGlt LOW DATE HrGH LOU ----August
21 6.0 5.0
22 5.5 5.0
23 6.0 S.O
24 7.5 4.5
2.5 7.5 4.5
26 B.O 5.0
21 3.0 5.0
28 6.5 5.0
29 7.0 3.5
:30 6.Q S.O
31 6.0 3.0
September
1 6.0 S.O
18 estimated at 7,000 to 9,000 (Pete Fricgeu. ADF&G, pers. comm.). These
estimates are based on the o~iuions of ADF&G personnel stationed at
Corrlova 8S actual escapement counts are not available for cohos. High
flow. and turbid water conditions during the peak spawning period usually
?revent counting spa~ing adults.
Spawning fish cannot use the entire Power Creek watershed due to Oh~n
Falls. Only the lover 2.5 ciles of the drainage is available. The AD?&G
also estimates that nearly half of the annual coho escape~nt utilizes
the creek above the USGS gau~ing station (}~Curdy, 1979). This involves
about 3,500 to 4,500 fish. The recainder of the run spawns below the
USGS gauge dOVtllltrem to Eyak Lake.
Spawning takes place from late August to early Decet:lber, usually during
periods of peak high water (McCurdy, 1979). Although spawning cay occur
in main channels of large rivers., locations at the head of riffles ill
shallow tributaries or narrow side channels are preferred. Opticum
substrate composition is small-!'lediUlll gravel. However. coho are
extr~ly adaptable and will tolerate up to 10 percent mud. Optimum
stream discharge 1s 3 •. 4 cfs (ADF&G, 1978a). Table J contains some
reported spawning depth-water velocity criteria for coho fr~ the
literature.
Information on the 1oc.a.t1cm of coho s'Pawning areas in Power Creek lOas
ina~eqWlte to determ.ne what iJ:l:pac:ts tiOuld result from a small hydro
projec:t, so field il1Vestigations were 1ni.tiated by rus and CE biologists
durins the spring and summer of 1930 to find and ma~ sites in Power Creek
that were potendAl coho 9pawning areas. FrOtl April 13-20, during 100:1
flows., the streadled was walke<i ft'O:!l the 1JSGS gauge to approximately 0.5
~1les below Ohman Falls. Using a band held cocpass and a range finder. a
rough habitat map of Power Creek ~s drawn on graph paper to 3. sC<lle of
1 n. -60' (See Appendix II). Major characteristics of the s1.1bstrate.,
stre~bank, streso channel, and potential coho saloon spawnin~ areas were
described. Biologists were unable to survey the stream all the way to
Ohman falls as the last 0.5 mile ~s in an active avalan~~e zone and uas
completely buried by snow slides up to 30 feet deep. In additian~ biolo-
gists walked the lower portion of POYer Creek from the U~GS l;auge rlowns~reac
to the beginning of the Paver Creek delta.
Because ot the snow depths (3-4 feet on the level) only the ~inst~~ of
Power Creek was surveyed in April. On June 4, 5, and a inves~igators
returned tD inspect the 0.5 mile stretch below Ohman Falls 4r~ to insure
that no areas adjacent to the cainste= had been ~s8ed. Co~~equently~
one small tributary was discovered (Appendix II, p. 2).
P~ults of the spawning ground su~ys indicate that the bulk of the
potential coho sal~n spawning areas in Power Creek are located below the
uses gauge. This area was judged to be outside of the project ~luence.
}lo~7ever, potential spawning areas were located \/ithin 0.5 mile upstreaCl
from the gauge (Appendix II pp. 1-5). TIlis potential spavcing habitat
ter1!linates just below the end of the Power Creek road. Areao were judged
to be potential spawning habitat by c~aring physical characteristics
with areas of known coho spawning elseVhere. SU~~ physical paraceters as
substrate cocposition. streac velocity~ and stre~ depth were considered
a~onR the prir~ry factors. The nost extensive ~otcntial hab1t~t in the
mainstem of Power Creek above the gauge is shown in Appendix II, pp. 3
· \hle 3. Spawning del)th-water velocity criteria for 3aloonid fishes found in Power Creek.
!)pec1es
lho
~6ho
Coho
,ho
Sockeye
,ckeye,
..
Cutthroat
utthroat
Depth
(Meters) (feet)
1.0-1.25
0.3-1.90
0.6
1.0-1.5
0.2-1.5
Velocity
(co/sec) (ft/see)
:l
21-70
1.2-1.3
0.5-J.0
1.D-3.0
1.754
a 1.75-1.8
1.0-3.0
0.35-2.37
Reference
Chambers et ala, 1955
Sams & Pearson, 1963
!hampson. 1972
Smith, 1973
Chachere at al., 1)j5
Clay, 1961
Hooper. 1973
Hunt.er. 1973
D'o11y Varden 0.7-1.4 1.13-2.15 hunter. 1973
-~t:\ ================================= J
;~!en8ured at 0.4 ft. above strear.bed.
~linimum
dource: Stalnaker and Arnette (1976).
-29-
Figure 14. Potcntinl
of Power Creek, April
Sii1moti spawning habit.:lt in the mainstem
19, 1980. Average daily scream flow 61
figllre 15.
5, 1980.
Pnt0nti~1 spawning
Avcrage daiLy strcam
area depicted in Figure
flow 6JO ds.
BEST COpy AVAILABLE
14 , june
efs.
.-lecreases, water velocity slows down, and sand and gravel are deposited.
~ing material is a mixture of fine sand, small gravel. and cedium
'l'">Jl with less than 1 percent large rock. Depths varied from less than
1 .oot to slightly over 2 feet. No vater velocity meaaurements were
aken. Average daily streamflowa from April 18-20 recorded at the USGS
gauge were 63, 61, and 61 cfs res?6ctively ana ~ere sufficient to cover
100 percent of the potential spawning areas in the mainstem (Figure 14).
)ther sections of Power Creek contain mtat were considered to be l1I:lited
>dpawning habitat due to unsuitable substrate, deep water, or the areas
were too small to hold more than a few redds (AppendL~ II pp. 1, 4, 5,
md 7).,
The remainder of Power Creek above the end of the road was not considered
to be important to coho spawning as the potential habitat is either
,absent in most stretches or very limited. On June 8, approximately 20
percent of the 0.5 mile sect:ion below Ohman Falls vas still covered by
avalanche slides and biologists were once again unable to view the entire
streambed. Since the sections of stream that yere open just above and
'below the slides were not suitable spawning habitat due to the stream
gradient and the presence of many rocks and rapids, the sections flowing
beneath the slides were presumed to be unsuitable as spawning habitat
also.
As previously mentioned, a small tribut'ary was discovered on June 5
(Y1gures 16 and 17). Just upstream from the USGS gauge on the outside of
~, ...... 900 bend in the creek a small tributary enters Power Creek (Appendix
;:< p. 2). The tributary contains clear water and is not milky like
. er Creek is during high flows. The origin of the water is a senes of
seeps and groundwater springs coming out of the ~ountain. It vas visually
estimsted to be flowing less than lO cfs. The entire tributary contains
spawning habitat (Figures 18-20). Salmon bones were scattered along the
banks where bears had evidently carried adults to feed on the previous
year (Figure 21). This area is shielded from the main stream by spruce
trees and a thick stand of alder. During the winter it is blanketed by 4
to 6 feet of snow.
Additional verification of spawning areas should be cade by viewing
adults later during the spawning penod. On October 2, 1980, biologists
were able to partially verify spawning areas by direct observatiou. Four
pairs of cohos were observed spawning alo~~ the bank of Power Creek about
300 yards below the USGS gauge. aigh flows and curky water prevented
investigators from adequately surveying the main stream. Despite the
turbid flows. biologists were of the opinion that the coho run had only
recently begun and that one additional trip in tti.d-Novet:lber 1930 would be
necessary.
Field work during spring and summer 1980 also involved determining 1£
coho salmen juveniles were over-wintering in Power Creek and if the
presence of coho spawning areas could be further identified by trapping
emer8ent fry.
~OhO' eggs in the gravel develop slowly durin~ the cold ~nnter months,
hatching in about 6 to a weeks (ADF~G, 1978a). The sac-fry remain in the
gravel and utilize the yolk material until emerging 2 to 3 weeks later
(:!ay-June). Upon e1:lergence, the fry school in shall~o1 areas along the
shores of the stream. These schools break up rather quickly as fry
establish territories. The fry defend these territories from oth~r
-31-
Figure 16. Outlet of only significant tributLlry to Power Creek
within thl! project arc ... , June 5, 1980.
Figure! 17. Photo identical co Figure 15 taken on Harch 27, 1980.
-32-
()
Figure 18. S<llmon sp':lwning. '-lrc.:l, tribut<lry to Power Creek .
•.•. ; .. ~. ~"'.-, : ':~:~. ~~
-J .. :
-' ..
'';':'" . f,ll.":
Figure 19. S<llmon spawning <lre<l, cribuc<lry to Power Creek.
BeST_CO PY'fAVAifABlE
-JJ-
Figure 20. Salmon spawning area, tributary to Power Creek.
Figure 21. Evidence of ~p,Jwning salmon scattered along the
bank~ by be.:lrs the previous year.
BEST COpy AVAILABLE
juvenile eoho with aggressive displays. !his territory is usually along
the shoreline or behind a log or boulder. From such a location the young
fish do noe have to fight the current, and can da1r~ out: to feee on surface
insec~s or drifting insect larvae. Juvenile coho grow rapidly during the
early su~r months. and spend the wineer in deeper pool areas of spring-
fed side ponds. Cohos also rear in ponds or lakes, where they feed alon~
shoreline areas.
The possibility of coho saloon juve.niles rearing in Power Creek over the
winter period was discussed with fishery biologists from the ADF&G and
the Chugach tta~!.onal Forest.. The general consensus \rclS that Power Creek
waa probably not an over-w1nter1ng area even though there were no dat:a to
sUPlJOr1: such a conclusion (Pete Fridgen, ADF&Gi Ken Holbrook, Chugach
National Forese, Cordoya, pers. camm.). Pete Frid&en (pers. cooc.) felt
that Eyak Lake is such a productive environment that cohos cost likely
migrate out of Power Creek into the lake after energence And would have
no re4son to return prior to outlldgrating as smol t8 to the saa. Fur'ther-
more, rearing habitae in Power Creek above the USGS p,uge preferred by
cohos vas felt to be 11~ted. Sloughs. backwat:er channels, ~d spring-fed
ponds are generally absent.
In order to verify Fridgen's' opinion, baited minnow traps vera placed in
a variery of streac habitat available to fish over-wintering in Pever
Creek. (Trap locations are all identified on the habitat caps in Appendix
II.) Approx1I:lately 0.5 t:dle of the strem: was saQPled on ;:iarch 27 and
28, Ap~il 18, 19, and 20. and June 4. 5. 0, anci 7. The results of the
trapping effort can be seen in Tables 4-9. No over-w1ntering juvenile
coho Yere cap~red. The results support Fridgen's opinion that Power
Creek is not a rearing area for coho sa1=on.
Coho salmon fry. n~~ly-emerged from the gravel, ~re captured by usi~g
cinnov traps and fyke nets from June 4-7 (Tables 6-J). ~enty one ~innow
traps and ~ fyke nets were set from the USGS 3auge to just above the
end of the Power Creek road (0.5 Qi1e). Dail7 air te~eratures reached
75· F causing the creek to rise rapidly from melting snow and assu:e a
milky appearance from glacial flour. ITigh flows hampered the trappiD~
opera-r.ion. One fyke ne"t in the 1:Iain channel of Power Creek ~as rl!!:loveci
after one day due to rising wa"ter and one ~innO'W' trn~ vas vashed a~ay.
Several traps became plugged with debris and d~dn't fish effectively.
Hevertheless, 33 nevIy emerged coho saloon fry ~ere c3?tured :llong with
119 juvenile Dolly Varden.
Of the 33 newly emerged coho saloon fry captured, 30 of thee were caUGht
near the junction of the small tributary with Power Creek (_~pendix II,
p. 2). The oajority of the fry were 25 em in length. Visual obser-
vations of the area indicate that the flow of the small tributary appears
to be independent of Power Creek except during extrftlely high • .-ater. At
. very high flows, Power Creek would oveTflov its normal oanks and inundate
the area •
.I) O"ly three newly emerged coho fry vere CB?tured in the cainsteI:I of Power
Creck. Due to the waro air temparatures and resultant runoff, the creek
rose steadily making it impossible to use a fyke net in the ~in stream.
Average daily flows recorded at the USGS eauge from June 4-8 ranged fram
a low of 455 cfs on June 4 to a high of 630 cfs on June 5 and 7. Any
coho fry that ver2 ~rging ..,ould iocediately be swept downstreaR 3S the
G r
Table 4. Summary of trapping results on Power Creek using ~~nnow trap8 9
~Arch 27 and 23, 1980.
1'ral) 3/23
1 IDV
2 15DV
3 0
Totnl l(iDV
Table 5. Summary of trapping results on Power Creek using minnow traps.
April I3-20 t 1980.
Trap
':otal
4/19
o * IDV
lDV
2DV
4/20
o
o
"'I'll additi01l 9 one dead DV vas found washed up on the bank.
**Trap 7 ~a8 placed outside of the project area in a deep hole vhere
the Pover Creek delta begins.
,~
:rable 6. Sumcary of ~rapp1ng results on Power Creek using c1nIlOW
tT'Sl's. June 4-7% 1980.
':'ral'l 6/4 6/; 6/7
A IDV Lost
3 3DV 4DV 4DV
C 3DV Plugged 2DV
D 0 Plugged Plugged
E lDV 3DV 1nV*
F 0 0 6DV
G InV 4DV 2DV
IT 1 eoho fry 0
I SDV 4DV
J 7DV 3DV
K 8DV SDV
L 4DV 3DV
!1 IDV 2DV. plugged
~ 2DV 2DV, 1 coho fry
0 lDV 4DV
P 6 coho try 7 coho fry
Q 0 5DV ~ 4DV IDV*
IDV* 1DV. 1 coho fry ... 3DV :mV, plugged ...
U aDV SDV. plugged
Subtotal 9DV 55DV 52DV
7 coho fry 9 coho fry
·*1 unidentified fry escaped
Table 7. Suncary of trapping rcaults on Power Cre~k using fyke
nets, June 4-7, 1980.
Trap 6/4 6/5 6/7
1 0, pulled
2 2DV, 6 coho fry IDV, 11 coho fry
Subtotal 0 2DV, 6 coho fry lllv. 11 coho fry
Table 8. captured on Power Creek \Ising mr.nuw r; tra'DS nnd nots JUt'te 4-7 1980.
.~f· canture method 6/5 6 7 total .
~1nnow traps 55DV 52DV 116DV
7 coho fry 9 coho fry 16 coho fry
fyke ne'ts a 2DV InV 3DV
6 coho fry 11 coho fry 17 coho fry
Total 9DV S7DV 53DV 119DV
13 coho fry 20 coho fry 33 coho fry
) , ... ,' "," "<.'> " ~.--
Table 9. Summary of fish captured on Power Creek during spring and summer~ 1980.
Ca~ture Hethod 3/28 4/19 4/20 6/4 6/5 6/7 Total
Ninnow traps l6DV 2DV 0 9DV 55DV 52DV 134DV
7 coho fry 9 coho fry 16 coho fry
Fyke nets 0 2DV lDV 3DV
6 coho fry 11 coho fry 17 coho fry
I w
Total 16DV 2DV 0 9DV 57DV 53DV 137DV (X)
I
13 coho fry 20 coho fry 33 coho fry
P) .. , ..... .. . '
velocity and de~th of the creek were such that biologists could not wade
it safely. High water conditions biased the trapping results and contri-
buted to the low number of coho fry captured in the mainstem.
n,e potential salmon spawning habitat located during April l~as observed
in June to c~are conditions at low flowa (April) with conditions at
medium to high flows (June). The potential spawning areas ~'lere eenerally
unrecognizable. Depths ranged for 3 to J.S feet cO'tlpared with 0.5 to 2
feet in April. Standing waves and swift water tiere present where slow.
even flows were the rule in April.
Sockeye Sa lmon
McCUrdy (1979) estioates 15.000 to 25,000 sockeye salmon enter the Eyak
Lake sys tam annually. but the percentage using Power Creek is un.1tnown.
Sockeye spawning takes place along the Eyak Lake shoreline and the lower
end of Power Creek from late August to mid-october. The oajority of
sockeye that spawn in Power Creek do so in the braided channels in the
lower delta. Optimum substrate composition is fine-medium ~ravel with no
more than 1 percent of the gravel being 5.9 inches in dia~ter (ADF&G.
1978a). Table 3 contains some reported spawning depth-water velocity
criteria for sockeye from the literature. Redd size generally averages
2.09 square yards (.WF&G,. 1978a).
According to the ADF&G. no sockeye are known to spawn above the USGS
gauge (MeCurdy. 1979). On Oetober 2. 1980, investigators observed
sockeye spawning in the rnainstem of Power Creek from the USGS aauge
downstream to the beginning of the delta, in the small tributary just
above the gauge (Appendix II, p. 2; Figures 18-20), and in another small
tributary located about 200 yards below the gauge. From the appearance
of the fish, there seemed to be two fairly distinct runs. !he small
tributary above the gauge contained the remains of 50 sockeye that had
been dead for quite some time. The live fish observed (365) were bright
red and still ae~ive1y spawning. In several places it appeared that
com?leted redds were being excavated. In addition, 25 dead fish were
strewn along the bank having been partially eaten by bears. This area
was estioated to contain 1.253 square feet of spawning habitat and is the
same area that rncs~ of the coho fry trapped in June came from.
The s~ll tributary downstream from the gause is located across Power
Creek from the road and enters the ~ainstem near the USGS cable car
A-fr~e. Fifty-two live sockeye were enumerated. No dead fish were
found. The spawning habitat was estimated to contain 600 square feet of
sui tab Ie gravel.
Sockeye observed in the mainstem of Power Creek below the USGS gauge were
spawning 80lely within 6 feet of the bank on both sides of the creek.
Although a considerable amount of spawning habitat exists in the mainst~,
it was not being used. Stream velocities appeared to be too fast. Until
Power Creek flows decrease substantially, biologists felt that th~
onjority of ~ravel in the mainstclll of Power Creek t-lOuld be unavailablo to
spawning salmon (both sockeye and coho). Due to the murky water. th~
number of sal~on observed was undoubtedly low. In spite of the poor
conditions, 107 live and 10 dead sockeye were counted.
No sockeye juveniles or fry were captured during the s~rin8 and sucmer
field work. Under normal conditions, sockeye eggs incubate for a period
of 80 to 140 days. '~en the eggs hatch. sac-fry remain in the gravel for
3 to 5 weeks and el!!erge in early spring -April and ~!ay (ADF&G, 1973a).
Sockeye spawning in lake inlets move downstream into the lake after
ecergence. In this case. it appears that sockeye eoergence was cissed by
sa~ling the stream in mid-April and early June. No sockeye were captured
in or near the small tributary above the gauge in spite of the fact
adults were seen spawning there in October. Another explanation for the
absence of sockeye fry in the minnow traps is trap bias. Sockeye fry are
planktonic feeders and may not have been susceptible to the bait used -
commercially prepared salmon egg clusters.
Dolly Va.rden
Power Creek contains a good population of Dolly Varden below Ohman Falls.
The ADF&G indicates that the sport fishery. although readily available.
is not utilized very much by local residents (Pete Fridgen, ADF&G. pers.
comm.). No population estimates are available for Dolly Varden.
Both anadromous and non-anadromous forms of Dolly Varden occur in the
Prince William Sound area. The largest populations of sea-run Dolly
Varden are associated with productive salmon systems. Lake systems are
of special importance as anadromous fish utilize freshwater lakes like
Eyak Lake for over-wintering habitat.
Spawning act~vity begins in September and in some systems extends as late
as November (ADF&G, 1978b). Inforoation on Dolly Varden spawning areas
and peak spawning periods for Power Creek is not Well known. According
to the information available, Dolly Varden have been seen spawning in
lower Power Creek just before it enters the delta and Eyak Lake (Ken
Ro1brook, Chugach National Forest, pers. comm.). No Dolly Varden
spawning areas were identified during field investigations. Hovever,
several large individuals were seen mingling with spawning ~ockeye in
October. Biologists assumed these fish" were preying on sockeye eggs and
were not spawners. Since Power Creek was st~ll too high for Dolly Varden
to spawn in the main stream, biologists felt that another trip to the
area in ~d-November would be necessary.. At that time Power Creek norna1ly
drops, the water clears up, and visual sightings of Dolly Varden spawning
would be much easier.
Dolly Varden eggs develop slowly in the cold water tecperatures usually
present during the incubation period. P~tching of the eggs occurs 4 to 5
months after fertilization. usually in March (ADF&G, 1978b). After
hatching, young Dolly Va·rden obtain food from their yolk sac and usually
do not egerge from the gravel until this food source is gone. According
to the ADF&G (1978b), emergence occurs in April or ~~y.
Juvenile anadromou8 Dolly Varden rear in streams before beginning their
first nigration to the sea. During this rearing period their growth is
slow, a fact which may be attributed to their somewhat inactive feeding
habits. Young fish often remain on the stream bottom. hidden from view
under stones and logs or in undercut areas along streambanks. Dolly
~ardcn young seldom swin near the surface and appear to select ~ost of
their food from the strean bottom (ADF&G. 1975b).
Power Creek appears to be an important rearing area for Dolly Varden.
Trapping results during Ha.rch, April. and June showed juvenile Dolly
Varden to be abundant and evenly distributed throughout the stream reach
from below the USGS gauge to above the end of the Power Creek road (over
0.5 mile). Eighty percent of all fish captured in Power Creek were
juvenile Dolly Varden (Table 9). The data in Figure 22 taken fr01!1 fish
captured June 4-7 suggests several age classes of Dolly Varden ~oIere
present. Lengths of Dolly Varden captured ranged from 35rnm to lSOrnm and
coincide with the age classes that represent the major portion of the
rearing fish population -a~e groups 0, I. II. III. and IV. The largest
individual caught (not included in Figure 22) was 200mm (3 inches) in
length. This fish was taken in a fyke net at the junction of the small
tributary with Power Creek. Due to the presence of emerging coho fry in
this area. this fish may have been preying on small coho.
Cutthroat Trout
The Eyak Lake system also contains sea run cutthroat trout. Very little
is known of their distribution or abundance. The ADF&G states that they
are found in Power Creek (Pete Fridgen, pers. coma.). Prince William
Sound is the northern and westernmost extension of the cutthroat trout
range in North America (ADF&G. 1978b).
According to ~en Holbrook (pers. came.), cutthroat can be caught in Eyak
Lake right after the ice goes out. The fish are not large, weighing 0.5
to 2 pounds and 12-18 inches in length.
Cutthroat spawn in small, clearwater. gravel-bottoned streacs during
April through early June. peaking iu ~y (ADF&G, 1973b). The f~~le digs
one or t!lOre redds about 1 foot in diameter and 4-5 inches deep. The eggs
are deposited in the redd. fertilized, and covered with 6-8 inches of
gravel. Hatching usually occurs in 6 ro 7 weeks. after which the sac-fry
remain in the gravel several additional weeks. Spawning activity occurs
primarily at night. After spawning. anadr~us fish often survive to
return to saltwater.
Cutthroat rear several years in small tributaries before !:lOving into
larger streams, lakes. or cigrating to the sea for the f1rs~ time.
Sloughs, side channels, deep pools, and beaver pond areas constitute
important rearing areas.
Overwintering at sea .is uncommon. and in the fall, both ~ture and
imcature cutthroat return to f~eshwater to ove~vinter in lakes or streams
with ~eep holding areas (ADF&G. 1978b). Cutthroat mayor may not overwinter
in the 8ame system every year. In-rnigrations occur from April to tloveI!lber.
The earliest in-migrants are mature spawners which enter froc April to
early July. Both imnigration and emigration occur primarily in darkness.
No evidence of cutthroat was found in rower Creek during t1arch, April. or
June. ~:o spil'mers or redcis l1ere observed. No juveniles or fry ~ere
captured. If cutthroat are spawuing in Power Creek, the population crust
he small or they may be using the delta area and not that section above
the gauge.
.. /',.".-.'.' •... '.-.
t-'.-, ':.:;;.
,
.~
-~.-.
. ,0
0::
, ......
=:l
~
35
30.
25
20:
10.
s.
_ ... --_ .... _-::.,.:---_.
, I
I
I
i
i
I ,Figure 22. Length -frequency graph of Dolly Varden. trapped!on
Power Creek, June ~-7, 1980.
, ,
'--,~-:-~i": .. -.....
, I
, I , I
I :-... ':~-.-. ~~ -r-:---: .
I
I
I
I ,
I , I
20 40
i
I
I . ...... "'---1---_ .. " ---
· I
· i .,
· i , i
I
60
'LENGTH IN MILLIMETERS
,~ESTC6py AVAILABLE,
.--" ... ! ..... -
-... ... ~ -.. _--... .--, ,
,
!
. ~-~ ~-~ .. j -~~.~ -:
i
, I
i
I ..
I :;
I
. : I
, , I
"I
I ----.-~ -----.,
. I
,
-~ I
,80
I
I
i
I
100
I
120
~ ... ' .. --:,
Other Fish Species
Pink salmon runs into Eyak Lake are ~~n~~l as a result of uplifting by
the 1964 earthquake. Picks do not spawn in Power Creek (HcCurdY9 1979).
Eyak Lake also contains round wh~tefish and burbot (ADF&G. 1973b; ~furrow.
1980). Both of these species are unco~n in the Prince ~111iam Sound
area. ~;either of thee, are found in Pover Creek. SOMe ice fisni!lg for
burbot and Dolly Varden takes place on Eyak Lake in the Wi..nter.
Upper Pover Creek
Above Ohman Falls the Power Creek drainage assumes a cousider3bly
different set of ~~aracteristics& The creek is a neancering stream ~~h
braided channels and lics in a vida, fla~, U-shaped valley typical of
glaciated watersheds. Stee~ countains rise ab~lptly on hath sides of the
y,alley floor. The floodpLa~ is ~ensive and LL numerous places clear
groundwater enters the main stream. Just above the falls. beaver have
succeeded in backing up water creatin~ large ponds and ex~ensive bog
areas (Figure 23).
Beeause of Oh~ Falls, anadromous fish are prQvented from using the
great l'!YJjority of the Pemer Creek drainage. '!'he ADF&G assur:1ed that upper
Paver Creek contained a reside~t population of Dolly Varden but no data
were available to su~port their assuapt10n (Pete Fridgcn, pers. comm.).
On June 5, investigators sampled about 1 mile of upper Fower Creek
including two clear groundwater tributaries. !he location of the
sanrpling was in the general vicinity of CE DrUl Site iH. The rnainst(!f!l
of Pover Creek was flowing too fast to sacple with a handheld seine.'tVio
b4.ited minnow traps were set, one in thli! t!'.a:i.nstec behind a 81:\8.11 debris
jam. and one at the junction of a clearwater tributary. ;io fish W4:!re
captured in the cinnow traps. Because the nain stream was cloudy froo
the glacial influence, it was difficult to see any fish except in very
shallow areas. Two ~ll fish were observed that biologists asou~eci were
Dolly Varden. The two groundwater tributaries were esti~tcd to be
flowing 20 to 25 cis and were easy to sample with a handheld seine.
Small fish 50 to IOCca long vare frequently observed eacaping the seine
and only two -were captured. Both of thet'l were Dolly Varden. In .:ulc1t.ion.
one ~olly Varden was found dead along the bank.
~e short perioc of time spent in upper Peuer Cr~ek only verified that
Dolly Varden are found in the upper por~ion of the drainage. :b con-
clusions can be drBWft as to their abundance or general distribution at
this time.
!!ountain goats are found in the higher elevations on both sides of Power
Creek. A hrief helicopter flight on June 5 above Drill Site 51 confi~d
the presence of four goats. Reynolds (1930) esticates probably no mora
than 20 f-:0at:s arC! found in ?awer Creek and Hu~pback Creek at anyone
time. Gnat habitat is usually =est~ictcd to the riC~etops aud steep,
rocky areas but Reynolds (1~8C) considers cverthinp, above 500 fcet in
elevation to be nountain coat habitat (Figure 4).
~1oo8e do not occur in the Power Creek drains!;€! (ADF&G, 1973). The
closest ocose r:mge is cue south and east of FOlier Creek in the Ibeck
-44-
Figure 23. Extensive wetland area above Ohman Falls created by
grounJwater flow and beaver dams.
BEST COpy AVAILABLE
Black bear are common near Cordova (ADF&C. 1973) and the Power Creek
watershed contains excellent bear habitat. Cne large black bear wae seen
foraging on the open slopes east of Ohnan Falls on June 5. As in the
ease of Humpback Creek. the ADF&G (197J) has not iceoti.fied any critical
deuning habitat in the Power Creek drainage.
The ADF&G (1973) has docuoented that the lower Power Creek. watershed
harbors seascnal conc~ntrations of brown bear. The bears are attrac~ed
hy spawning ~al~n which serve as an ~ort3nt food source. Personnel of
the. Cardova offices of the ADF~G and Chugach tiat10ual Forest ind1c.ate
that local people tend to avoid the area when sa1!non are spawning eua to
the abundance of brown bears (Pete Fridgen; Ken llolbrook. p~rs. comm.).
Reynolds (1980) es~imates 12-15 bears utilize Power Creek.
CE personnel flying to Drill Site #1 observed a brown bear sow and a
large cub several tines just above Ohman Falls ~uring early June (Chuck
Floyd. CE, pars. comm.). In addition. brown bear hair and acata uere
found along the Pover Creek trail below O~~ Falls by investigators on
June 5. 'nte rC!1Daina of a freshly killed porcupine Here located the sar.e
dny across Power Creek froc the uses ~auge. Large pav prints in the snow
indicated the ?redator was a brown bear. On October 2, nucerous freshly
eaten sockeye salmon and hear scats were observed along the sr.lall spawniuS
tributary just above the OSGS zauge.
Si.tka black-tailed deer are widely distributed throughout the Cordova
area. Evidence of deer in ?ower Creek was ~n~l. Two fresh pellet
groups were seen on the Power Creek trail on June 5. The ADF&G (1973)
states that the mainland ceer population is low and has not identified
any vinter range in the Power Creek draina~e.
Other tmnm:UIls known to occupy habitats in Paver Creek include: reel
squirrel, porcupine, hoary ~arcot, beaver, ouskrat. and river ottar.
Birds
The coniferous forest is the 008t ext~nsive vegetative type in Paver
Creek near the project features. !he majority of the hird species found
there are forest dyelling passerines. rnes~ include, but arc not l!=.ited
to: t>lilson'a 'i3arbler, yellov warbler • ...nnter \1t'en, ruby and golden-crouneti
kinglets, varied and hereit thrushe~. American robin. douny ~ooGpe~~er.
Steller's jay~ COl:'lI:"On raven, and several s!'arrous. The oost COt:i1!lOl1 bird
found along the Pover Creek corridor was the dipper. S!'ruce grouse.
northwestern cr~s. and several avIs are also found in forested areas
near Power Creldt.
Wetland habitats associated with the project include the Pover Creck
-delta and a lar3e series of beaver ponds an~ sloughs above Oh~n Falls~
The large network of beaver ponds has created suit~le nesting habitat
for SOT.!e waterfowl and shorebirds. At least one pair or whistling S~'ians
and several pairs of C3nada geese ... -ere utilizing the ponci areas for
nesting. Other birds observc~ were: arctic tern, spotted santi?iper,
varied thrush. and greater yellowlegs. !;o survey of the 'Wetlands in the
Pover Creek delta ~TaS oaee because a st:all hydro project upstrelm was
helieved to have 'Co impact on this area. Nest1ne habitat is available
fer duckD, ~eese, swans, and shorebir~s but no cst~te of the nu~ber of
birds nesting on the delta is ~ailable.
.. iJ····.~.··,·' ..
~.
Aquatic habitat of Eyak Lake adjacent to the Power Creek delta is used by
several species of ~terfowl for feeding and ~olting. during the succer
and early fall. ~igrating ducks and geese also utilize the lake as a
staging area prior to flyin~ south. Species observed durin~ spring and
early summer incluce: whistling swan, Canada goose, oallard, green~nged
teal, co~n ~rganser, bufflehead, and pintail.
Northern bald eagles are numerous throu~~out the lower end of Po~er Creek
and all along the Eyak L3ke shorelL~e. Gusey (1973) states that ~uring
the winter of 1969. 416 bald eagles were observed feeding on apawnea-out
salmon at Eyak Lake. Personnel from the ADF&G and Chugach !~at10nal
Forest could not eocuaeut any active or histori~ eBBle nest sites on
Pover Creek or the northern am of Eyak Lake (HcCurdy. 1979; Carvin
Bucaria, wildlife biologist, Chugach ~lational Forest t pers. comm.).
Since suitable nesting habitat is available. a helicopter survey ~as
conducted on June 5 to thoroughly search for nests. The entire Power
Creek drainage from Drill Sj.te 111 to and including the delta and the
shorelj.ne of Eyak Lake v.f.thin 2 Illiles of the t:Xluth of Paver Creek was
surveyed. No bald eagle nests vere located.
At this point in the CZ's study. design plans for all three proposals are
very prelLainary. Therefore. reliable predictions of all adverse L~acts
are no~ fully possible a~ th~s time. Prior to submission of a Final
Coordination Act rc?Ort, design ?lans and specifications of all project
features should be submitted to the rwS. Additional information necessary
to cor.plete our analysis is the exact loeation of all project fe3turcs
and locations of any necessary access roacis ano tr3nsmissiou line corricors.
Crater Lake -The =ajar potential impacts of the lake ta~ proposed for
this project can baSically be summed up in three categories: diversion
dam construction, land clearing for the penstock, anc cevater~ng the 1aka
outlet.
According to the Cl!. no road would be b'uilt into Crater Lake (Tom :IurdocSc.,
CE, pera. comm.). All construction r.~ter1a1s yould be flow~ in by helicopter.
The e:act d1~nsions of the diversion cam have not been deteroinea although
the l1aconnaissance Report suggests a concrete structure 5 feet hieh and
15 feet long (en ~~ Hill. 1979). The exact loc3tioa of thee lake tOlP has
not been establi~ed either. The CE envisions water being drawn off very
close to the present level of the lake and not iro~ SDr.e point in deep
~~ter (To~ ~~rcock. CE, pers. comm.). The dL~nsion of the pipe would be
18 inches and capable of carrying a nax~ of 4 efa.
Envir~ental i~actB from constructing a small concrete diversion ~uld
be minor. Some wildlife habitat WIOuld he covered up by the dOlm itself
and ?err.~nently lost. Habitat adjacent to the present lakeshore would
also be inundated by raising the level of the Lake enough to draw off
'>later. no estimate of the aoount of habitat that ~rould he inundated i::;
~vailable but it is not anticipated to ce very sreat. ?esicient wilc11fc
affected by these actions uould ?robabl,. be li::ited to :loall roGents.
During construction of the dam ane lake tap, h~n activity and noise
associated ~th helicopter traffic yould undoubtedly disturb resicent
spee1es of Wildlife, such as ~untain goats, black bear, Sitka black-
tailed deer, and passerine birds. This disturbance, huwevcr, ~ould on17
."l be short-lived. Once construction is finished, disturbances from
helicopter traffic and the presence of hucans would return to pre-
construction levels. !~o long-term adverse i:mpacts to rlldlife should
result.
In order for helicopters to land safely, sooe habitat may ~ave to be
disturbed for the construction of landing pads. raese areas would prob-
ably not revegetate well and may end up as long-te~ scars.
The water level of the lake would not fluctuate dratJatically, so the
rainbow tTout fishery in Crater Lake should be affected very little. The
CE does not envision a large draw down primarily because the project
would only be operable from May through October, the period of highest
runoff (Tom lfurdock, CE, pers. COUDll.). lfcCurdy (1979) indicates there
may be some natural fish reproduction in the lake. Any draw down in late
summer could then expose eggs hatching along the lakeshore. The poten-
tial loss of any natural reproduction is probably not significant. Even
without the project the fishery is only kept viable by stocking hatcllery
rainbows every 3 to 4 years.
In order to construct a 4,80o-foot penstock of lS-inch pipe frOJ:l Crater
La~~ to Orca Inlet, a swath of vegetation would have to be cleared through
a dense Sitka spruce forest to the pO~ierhouse near sea level. Bec~use
the terrain is 80 steep, the methods used to clear the vegetation and
install the pipeline would have a direct bearing on the eventual impacts
to the environment pri~~rily from erosion. For example, hand clearing of
trees and shrubs would have less detrimental icpacts than the use of
tracked vehicles. At this time, the CE has not determined the method of
vegetation recoval nor whether the pipe would be buried or elevated.
Consequently. evaluation of the icpacts of the penstock placement cannot
be adequately assessed at this time.
The end result of a cleared strip ~hrough the forest would be visible to
boat traffic along Orca Inlet. To soce people, this would be esthetically
un~leasant. The powerhouse would be constructed near the Orca canneries
adjacent to an existing transmission line from Cordova. Impacts from
this action would be localized and may require removal of soee vegetation
and ground leveling.
The diversion dam would eliminate the natural overflow of water out of
Crater Lake during the months of ~~y through October. Pink salmon
periodically spawn in the outlet wa~ers at the junction vith Orca Inlet
froo late July to early August. The available spawning habitat is small
but up to 200 fish have been observed using the area. Unless the tailrace
water is returned to the outlet drainage prior to entering Orca Inlet.
pink salmon spawning and the survival of eggs would most likely be severely
reduced or eliminated entirely,
One unq\~ntifiable impact would be what effect the project has on people
who are used to trout fishing at Crater Lake. The area is highly scenic
and undisturbed. The dam. penstock, and disrupted vegetation would most
likely decrease the quality of the outdoor experience for sore people.
This impact appears to be unavoidable.
HUnpback Creek -I~acts to the environment associated <Nith this project
include construction of a small diversion dam. partial dewatering of the
creek, land clearing. and the possibility of road construction.
AAI in the case of Crater Lake. the actual impacts of construct.ing a small
concrete diversion dac on upper Humpback Creek would be minor. The
("""\ d1.version would be built approJd.mately 2 miles upstreac fron the ODuth of
J} the creek. The Reconnaissance Report indicates 3. 5-foot x 30-foot struc-
ture would be adequate (C1l Z}! 111.11. 1979). The locat:ian of the diversion
is well above the pink saleen spawning area and no fish passage facilities
would be needed.
A portion of the creek behind the diversion \iOuld be inundated. The
exact size of the 1mpound~nt is unknown but it would not be very large.
Some streambank vegetation would be drowned but the impacts are not
considered to be significant.
A flume 6~6Z5 feet long and a 70o-foot penstock would carry water from
the diversion to a powerhouse about 0.Z5 to 0.5 mile from Orca Inlet.
The diameter of the penstock would be 30 inches and capable of carrying a
maximum flow of 40 cfs. !be proposed location of the po~rhouse would be
very close to the uppermost old log dam on Humpback Creek previously
described (Figure 3). !be water that is removed at the diversion yould
be returned to the creek above the spawning area. Therefore, ,no reduction
in flow through the s~awn1ng gravel would occur. If the powerhouse ~iere
situated in the right place, this project could actually enhance the
survival of pink salmon eg~ and the fishery by returning water to
llucpback Creek below the deteriorated log crib dam further downstream
from the proposed powerhouse location (Figure 9).
~ By cutting down the peak high flows and bypassing the large amount of
/ gravel backed up behind the log crib dam (50,000 to 60,000 cubic yards),
egg mortality from gravel scouring downstream should decrease. The
project would only operate from Hay through October ~hen floWs in
H~back Creek are highest. Drawing 40 c:fs out of the creek above the
dam can only help cut down the amount of gravel moving down the stream.
The Reconnaissance Report indi~tes that to ensure some ~ter in the
stream below the diversion. flows equal to twice that of the 7-day,
2-year low would be allowed to pass the structure at all tices. This
minimum flow was found to be 1.4 crs (CH.,M 111.11). :!cCurdy (1979) states
that there are no fish above ~he log dami. In addition, sa~ling done L~
June 1980 fa~led to detect any fish in the streao. Adverse icpacts of
the reduction in flows would probably result in 3. decrease in the proauc-
tiou of aquatic invertebrates in that section of the strcao and pOSSibly
eli=ination of some passerine birds like the dipper.
At this stage of the study, the CE has not determined the extent or
location of any road construction necessary for access to the powerhouse
Site, access to the point of diversion, or for cons~ruction of the trans-
mission line. Therefore, the FYS cannot adequately assess the impacts of
roads until fu~her info~tion is r~ceived.
Generally, some adverse impacts of road building include. but are not
li~ited to: re~oval of wildlife habitat. interception of ground ~ater
flow, increase in erosion. and allOwing motorized vehicles access into
areas previously inaccessible.
Approximately 3.6 ~les of 15 Kv traU8~ssion line vould be constructed
to tie into the present line from Core0V8 that ends at the Orea canneries.
Potential 1cpacts cannot be adequately de6Cr~bed until a detailed route
for the line has been chosen and whether the li~e ~ould ~~ constructed by
road or helicopter. Regardleo8 of ,mere the line is ?laced, erosion
would result frca land clearing activities. However, an acequate erosion
control plan can niniaize the amount of secioent or debris capable of
entering the aquatic environcent.
Transmission poles are often used by large rap tors for perching and can
be a source of mortality fram electrocution if the lines are not properly
s~acecl.. It has been deten:dned that grounding practices on distribution
aud transmission 1inee from 4 Kv through 69 Kv can be a sub8tauti~1 cause
of raptor deaths (Raptor Research Foundation~ 1975). Because of the
density of bald eagles all along Orca Inlet, this is ~ definite concern.
However, proper line construc~iou can eli~inate any mortality of ~agles
f~om e1ec~rocutiQu.
Visual impacts from transuission lines and corridors can be significant.
In many instances. it is difficult or impossible to blend th~ ~to the
background vegetation. In this ease, a 15 L{v line docs not require huge
steel touers and by using woocen ~oles and careful clearing techniques,
this tcpact can be c1nimized.
During construction of the project when a work force is present, bear-
human encounters cay result. !he ADF&C (1973) has docucented seasonal
concentrations of brown h~ar drawn to lower Huopback Creek to feed on
spawnin~ ?ink salmon. Spawning activity, and thus the presence of be~ro.
would occur from early July to mid-September. :h~s saF.e t~e fr~ewor~
would MOst likely be the height of construction activity. Preven~in3 a
nuisance bear situation by disposing of all refuse and no feeding of
bears ~ould hel~ reduce bear-h~laD encounters.
P~er Creek -Oh~n Falls 1s situated at ~le 2.5 on Power Creek and
blocks saloon moveQent any further upstream. The Reconnaissance Report
identifies a suitable site for a diversion dac above the falls. !here-
fore, no a1g~ation block would result. and no fish pansa~e facilities
~ould be requir~d. tlon-anaciror"ous Dolly Varden are che .-mly :ish species
that have been identified in ro~~r Creek above the falls. Sone Ynt~rfow1
and shorebirds nest in the wetldnd areas and poncs createG by bedver
adjacent to the proposed diversion site. The diversion 110ulJ create no
significant ilnpound:lent (C13 211 Hill. 1979) and cons~uently i~act fish
and wildlife species for only a short ti~ during construction.
A combination of pipeline and p~nstock YOuld carry water from the diver-
sion to a powerhouse tentatively located near the present site of the
USGS gauging station along the Paver Creek road. Approxi~te1y 1.5 niles
of Po~er Creek ~ould then be part~ally de~atered. Alcost the entire 1.5
miles provide rea~ing habitat for Dolly Varden and the 0.5 nile stretch
above the ?,aup,e contains spD\oming h<lbitut for aprrox:L~te1y 3,5GG to
4,,500 coho sa.l~n and possibly a few sockeye salr'lOn. The ~ount of ~later
left in the creek ~9uld have a direct bearing on ~lcther 2o~er Creek can
continue to 9UPpo~t populations of coho salrlOn and Doll:1 V:lrcen to the
!!".!lglliturle it does nov. The ~r::!atest ippact on coho salnon ,;ould occur
during the winter and early spring ronths -Jecet::ber through April. 'I1d.~
is the ?et'~od of natural low flows ~;hen c1ve~ting t.:ater would take :1
. ro ortionall hi her erclr!nta~e i he stream. Coho e"''''' c atin· ... in
,spawning gravels coulc:! be exposed by removing tlater and result in consid-
erable mortality fr~ dehydration or exposure to freezing t~era~ure8 •.
~Table 10 contains a sumcary of the percen~ of the tine the ~Atural streao-
p ,flaw in Poyer Creek would exceed the minir.ru.n allowable flov necc!:sary for
3!"!all turbines ra~ed at 1.25 I"Iegawatts efiol) to 10 :!w. It is readily
apparent that a 10 }N turbine could no~ operate during the loy flow
~onths (December to April) and therefore cause no inpact on coho eggs in
the gravel. However, this would not give Cordova a year rotttld source of
hydropower. It is also ap~arl!nt that a 1.25 ~lw turbine could conc:eivnbly
take the entire streamflow during the enret'lely low :low nonths in any
given year eliminating any survival of cohos above the powerhouse. Since
four of the 1.25 Hv plants could he hooked up to provide 5 ~!w of paver
curing high flows, L~is scenario is feasible from an ensineering stanupoint
(Tolll Murdock. CR. pers. comm.).
Direc~ observation by biologists, coupled with recorcs froQ the uses
gauge. indicate that for the I:'.onths of Hay throu~h Uovenber, adequate
flaws would remain in Power Creek to allow coho fry to outmigrate to Eynk
Lake and adult coho to ascend the creek and spaloll1 despite the rC!duction
in flow needed to run a 5 ~~., plant. In fact, a reduction in flo~ during
that t10e period t:2SY even be benef ictal.
The ~~s did not locate any Dolly Varden spawning areas above the USGS
gauge, but the presence of young-of-the-ycar (age Class 0) taken in
~nnow traps during early June suggests that spavning ~oes occur above
the gau~e. Impacts an Dolly Varden eggs incubating in the gravel -would
~be s1ciliar to those described for coho salnon. Removal of water durinQ
"Ccj; the critic:.al lev flev P.lOtlths would expose eggs to dehyrlration and freezing.
Inpacts on juvenile nolly Varden over-wintering in that portion of Power
Creek that is dewatered would probably not"be as severe. Juvenile fish
(age classes 0 through IV) are d~str1buted throughout the strean. TIle
great cajority of them were captured in paola which are preferreci hahitat.
Reducing winter flovs to zero would ~st likely not dry up the entire
stream as the rleeper holes woulc still contain Yatar and 80~ groundwatar
would probably still surface in the streambed. H~~ver, c~petit1on for
food would increase as the anount of available habitat decreases. In ~he
absence of appreciable running ~ter, the ~ools would freeze over and
oxygen levels even~ual11 decrease.
Adverso icpacts on coho sal~n ~ou1d be eli~1natcd if the powerhouse were
located near the end of the Power Creek road. This site is above the
potential spawning area. Adverse impacts on Dolly Varden could b~ ~ni
oized, but not eliminated, if the poverhouse were noved ups~rea~. Dolly
Varden juveniles probably over-qinter in Power Creek all the way to Ohnan
Falls. In ~ddition9 it is highly likely that Dolly Varcan are spawning
above the sauge also.
The diversion and eventual return of water to Power Creek should not have
any iMpact on Eyak Lake or on the strcac belm~ the selected ~owerhouse
si tee t!o change in ~ter tt"tTperaturlls or le.vels of saturatad gases would
~esult as t~ere ~ould be no large stora£e rese~1oir Yith this proposal.
~cour1ng of the stre.am channel below the powerhouse tailrace could be
~1n~ized by installing an cner;y d1ssi?ator.
.. ~
Table 10.
Percen~ of tine stre~fl~ exceeds ~ni~run allo~able flo~
for turbine operation on Po~er Creek
(run-of-the-rivcr).
Source: Tom z!urcock, Corps of Engineers •
<j) .. '".-..... . ,. r.'
';'-:
The FWS did not identify any other fish species using the mainstem of
Power Creek above the uses gauge. A minimum of 440 (365 l~ve and 75
dead) sockeye salmon were utlizing the s~All tributary that enters Power
Creek above the gauge. H~ever, this stream appears to be inde?endent of
Power Creek flows. The source of water is a series of springs and seeps
and seems to be relatively constant. Biologists could discern little
difference in flow betwe~n June and October although no neasurements were
taken. Rcnoval of water from Power Creek upstream should ~ave no effect
on this tributary. For that reason, no adverse impacts are anticipated.
It is highly likely that some sockeye are spauning in the mainstem of
Power Creek within 0.5 mile above the gauge. However, spawning habitat
next to the bank is l~ted and stre~ velocities are such that during
the peak of the sockeye run the preferred spawning habitat is unusable.
The bulk of the spawning area above the gauge probably does not become
available to sal~n until the middle of November when streamflows decrease.
CoinCidentally, mid-November is when the bulk of the cohos are ready to
spawn and the sockeye have already spawned and died.
Available data in~icates that anadromous cutthroat trout are present
above the gauge. Since the FWS's sampling effort was not intensive, this
s~ecies may have been misaed. However, if the population of cutthroat
was sufficiently large~ sampling should have detected thee. If cutthroat
are spawning in Power Creek~ the population must be small or they are
spawning in the delta area.
The ADF&G (1973) has documented concentrated brown bear use durine the
salmon spawning period on lower Power Creek. }.ny great reduction in the
coho run above the gauging station could elic1nate a valuable food source
for some of the big bears and force more of them to forage closer to Eyak
Lake. This could result in a 8reater feeding density of individuals than
the species is willing to tolerate. Younger bears would probably be
chased off and have to forage closer to town increasing the likelihood of
bear-human encounters that ultimately would result ~ more bears being
killed in defense of life or property.
Adverse impacts to other big game animals are not anticipated. (~0ge are
not found in the Power Creek drainage. Sitka black-tailed deer are not
abundant. ~1ountain goats, although present in the drainage, should be
affected very little. Their narrow range of habitat preference during
most of the year precludes use in much of the drainage except the steep,
inaccessible rock cliffs and precipices. Reynolds (1980) indicates goat
habitat does extend down to '00 feet. In the area of Ohman Falls and
upper Power Creek the SOC-foot contour comes right down to the valley
floor (Figure 4). It is assumed that any downward migration of goats is
seasonal and coincides with winter snowfall. Since any construction on
the diversion dam or penstock is not likely to be done during the winter,
no project related impacts on goats should occur if individual goats
decide to winter in the rocks near Ohman Falls. Adverse impacts to
smaller nsmmals and birds utilizing the coniferous forest habitats have
not been quantified but are not expected to be significant.
The transt!d.ssion line corridor is depicted in the Reconnaissance Report
paralleling the Power Creek road all the way to Cordova 4 !he report also
rec~nds that the line be buried. Since bald eagles concentrate all
along Eyak Lake during the salmon spawning season, a buried poverline
( ...... "\.~.:
fJ
would eliminate any chance of electrocution and is preferable. Burying
the line would also eliminate any visual impacts. llowever, even if the
line is elevated, electrocution can be eliminated by proper line spacing.
DISCnSS!ON
Crater Lake -Our analysis of the potential adverse impacts of a lake tap
hydro project at Crater La~~ indicates that wildlife resources should not
be significantly affected. Potential impacts to pink sall'JOn spawning in
the outlet waters of the lake adjacent to Orca Inlet could be eliminated
by returning tailrace water above the spawning area.
Short-term impacts to mountain goats~ bear, and deer from construction
activity at the lake would cause these species to avoid or temporarily
abandon the area until the project is completed. Due to the short
working season at the lake's elevation, setting time constraints to
mintoize impacts on wildlife is not realistic. However, if the divarsion
and lake tap can be completed during one work season (July through
September), impaets from the presence of humans and construction noise
should be l!dnil:ta1. Beeause no road would be built to the lake, helicop-
ters would be necessary to transport all materials and workers to the
site. In order to minimize detrimental icpacts to game species from
helicopters~ the CE should insure that contrators use the same access
route to and from Crater Lake. tfe reeommend that the ADF&G office in
Cordova be consulted and a route chosen that would avoid ~~own concen-
trations of big game. primarily mountain goats.
The only fish in Crater Lake are rainbow trout. Raising the level of the
lake and subsequently drawing it down to release Yater should have little
iopact on the trout populAtion. There are soree indications that limited
reproduction takes place and drawing the lake dawn could expose eggs
hatching along the shoreline. However, the ADF&G stocks the la~~ every 3
to 4 years with hatchery fish because the lake cannot support a naturally
reproducing population.
One unquantifiable impact would be ~mat effect the project has on people
·~o are used to fishing Crater Lake. The area is highly scenic and
undisturbed. The diversion, penstock, and disrupted lancscape would
probably decrease the quality of the outdoor experience for so~ people.
In order to ~n1mize the visual impacts. any soil disturbances SUcil as
helicopter landing pads should be carefully planned to avoid leaving an
unsightly scar that would not revegetate for cany years. r~ganic soils
excavated during construction should be stockpiled and spread over
disturbed sites to eneourage revegetation. Any equipment used to con-
struct the diversion should he operated only in the 1cmediate vicinity of
the project to prevent unnecessary damage to the fragile alpine vegetation.
Waste construction oaterials should be cleaned up and recoved after
project completion.
In order to build the penstOCk, a swa~h oi tiober would have to be
removed from the vicinity of Crater Lat~ down the ~ountain side to the
proposed p~~erhouse location near the Orca canneries. Presently, the
slope is covered with a dense stand of western hemlock anc Sitka spruce.
Impacts from this activity ~~ould result in the elimination of some ~·r.Uci
life habitat and, depending upon construction techniques, may iopact pink
salmon spawning in the outlet waters of Crater Lake acjacent to Orca
Inlet. Impacts could be minimized by clearing trees and tall shrubs
using hand tools instead of heavy equipt:tent and poaitioning the penstock
and powerhouse.a safe distance away from the small watershed that drains
Crater Lake. The ~iS will be able to provide the CE with a n1n~uo
acceptable distance after a site reconnaissance scheduled for t.li.d-Novecber
1980. The tailrace from the powerhouse should be constructed so that the
water is returned to the small watershed draining Crater Lake prior to
entering Orca Inlet. This would insure that pink salmon spawning habitat
is not eliminated.
Any swath cut through the timber would be visible to ferry and boat
traffic on Orca Inlet •.. Careful clearing of trees and high brush using
hand tools could minimize this visual impact.
H~back Creek -Should this proposal be selected, design plans and
information pertaining to all project features including the exact
location of all roads, stream crossings, and the location of the
transmission line corridor should be supplied to the FWS.
With the information available, adverse environmental impacts that have
been identified ·to date do not appear to be significant. The project
location is well above the pink aal~Dn spawning area and no fish passage
facilities would be required. No fish have been found in that portion of
the creek that would be partially dewatered. Impacts from the impoundment
behind the diversion dam are judged to be insi.gnificant. No bald cagle
I'~~.. nests are located within 2 miles of the project ares. No long-term :.p impacts on big gace animals have been identified.
'~.'." ... ' J
Our analysis of the proposed powerhouse location reveals that if the
powerhouse were situated dawnstream~rom the deteriorated log crib dam,
this project may enhance the survival of pirut salson eggs and the fishery.
The tailrace from the powerhouse should return water to Hucpback Creek
below the log crib da~. I~ediately below the dam would be prefer3ble.
This action WDuld reduce flows over the dam by 40 cfs and help alleviate
gravel scouring of spawning areas downstream. An energy dissipator
should be installed to prevent scouring of the streambed where the tailrace
discharge enters the creek. '
In order to reduce the amount of land clearing, the transmission line
should parallel any road that is built for access to the ~outh of Hu~
back Creek. The line should be built to eliminate any possible chance of
electrocution of large raptors. Transmission line construction should be
governed by "Suggested Practices for Raptor Protection on Powerlines"
(Raptor Research Founcation, 1975) and Bulletin 61-10 prepared by the
Rural Electrification Ad~nistration, U.S. Department of Agriculture,
dated March 9, 1979.
Improper disposal of food-related garbage would attract bears and lead to
bear-human encounters. This results in removal or destruction of offending
bears. During construction, all food-related garbage should be placed in
cetal containers and rc~ovcd from the site daily. At no ti~ shoulci
construction crews be allowed to feed bears.
?Cn1er Creek -The ~!S has not received t:luch DOre infor.:tation on this
project than what is contained in the Reconnaissance Report. Therefore,
any prediction of 3dverse inpacts can only be done on the information
available in that report.
The Reconnaissance Report indicates that this site is the ~st feasible
of the three proposals for paver generation (CH~1 Hill, 1979). Our
anal11lu of potenti011 ~acts. also points out tnat this project could be
~he ~s't detril:".eDtal in tel"T,!.s of adverse effects on f:isn, pri::'.arily coho
'Jal~n and Dolly varden.
The diversion daD 'muld be built above Ohl:lan Falla, a natural barrier to
fish migration. ~erefor~, no fish pasBage facilities are necessary.
novever, a cocbination of pipeline and ~eU8tock would draw water frae the
creek aDd eventually return it a~pro~tely 1.5 miles downstrcac. This
1.5 mile stretch would be partially dewatered. Al:lOst .the entire 1.5
atlas provide rea~ habi~t and suspected spawning habitat for Dolly
Varden and a 0.5 ~e reach above the uses 3auge is spawning habitat for
coho' sal~ and ~8t likely a few sockeye salmon. The flau regice in
Power Creek 18 such that removal of ~ter would have the greatest ~act
aD salmonid eggs 1D the grSgel fr~ Dececber throu~h April -the period
of nAtural low flows. By utilizing a series of small turbines, it is
po.s~le to t~ke all the surface vater from the cre~k in the low flow
cODtha. The eDci result ¥auld be the loss of any saleonid eggs 1ncuha. ting
in the gravel in Powe~ C~eek aba.e the powerhouse location. the ground-
~ater coD~r1bution to the s~ream be~en ~An Falls and the gauge is
tmknOVft. Unless the a can supply the 1."'lfortlation that sllff~:!.eut ground-
·.a1ater rtft:3jns du:1ng the low flow man'tha to k.eep salconid egoS allve, the
PWS c:&mlO't assume groumiwatar flow is a significant factor.
,'nte potential loss in sall:mnid production cguld be eliminated <lne of NO
~va~s: (1) Develop aanthly flow require!!!en~s for Paver Creek necessary
,-or optil::um salMon proeuct1oD and survival. Thia alternative ~ould
'require aeditional field work. and funding in order 'to d~elop recOtl1lX!ndeci
flaws. Winter flaws in Power Creek get low enough ~;at it is anticipated
that the range of opttcuc !lova would be very narrow O1Dd ~st likely
coinc:1c!e with natural flo..,.. Being realistic:, surplus watt:r for power
genera~ion would probably nat be av4ilable during the winter ~nths. (2)
~CNe the proposed powerhouse lcc:at1on upstnmll to the t!nd of the Paver
Creek road. !his alternative would require the CE to calculate the less
in elevation from the uses gauge to the enC of the Power Creek road and
dete-mine if the correspODdi::.g loss in head is ~ll enough to oar..a t..'lis
recomcencation acce~table.
Addi tiona! 1nfor.::1~ian is necessary to docUJ:lent coho sall:':On ilne r-olly
Vareen spawning areas by visual observa.ti.on of acults. A field trip is
scheduled for ~d-4Jovemher 1930 to provide this inforcation.
Re~areless of the powerhouse location. the tailrace should be constructed
to preven~ scouring of the streambed where discharge water returns to the
creek. In addition. the dischar~ should re-enter the creek so it does
not serve ae an attraction tD adult salmon returning to spawn.
Land clear1D~ activities and access ronGs for the penstock and pipeline
_ tlOuld remove Wildlife habitat me cay S4ilrve as a source of silt froc
/~ro8ion. ~ever t until further i:lfornation is received frO!:! the CE on
~he location of those structures and acidition~l road~, ~e cannot co~nt
on the potential icpacts of those project features.
7he tTans~ssian line corridor should ~losely parallel ~~e Paver Creek
road. This will miuici%e the a~unt oi land clearing necessary ~nd
reduce the r~k of erosion. A buried power11ne ~ulc require very little
land clearing. eliminate any chance of electrocuting bald eagles, and
create no visual impacts. For those reasons, it is preferred over an
elevated line. An elevated line can be built to eliminate the electro-
cution of eagles (Raptor Research Foundation, 1975; U.S. Department of
Agriculture~ 1979) but requires more land to be cleared and creates a
significant visual tcpact.
Improper disposal of fooe-related garbage would attract bears and lead to
bear-human encounters. This results in removal or destruction of offending
bears. During construction. all food-related garbage should be placed in
metal containers and re~oved from the site daily. At no time should
construction crews be allowed to feed bears.
REC~~ATIONS
The following recommendations are provided to minimize the potential
environmental impacts of constructing three small hydro projects near
Cordova:
Crater Lake
1. That the exact project design plans be provided to the FWS as soon
as they are available;
2. that the CX.consult with the ADF&G office in Cordova to choose a
helicopter route to avoid traffic in the vicinity of known concen-
trations of mountain goats;
3. that any organic soils exc~ated during construction at the lake be
stock~iled and spread over disturbed sit~~ to encourage revegetation;
4. that any equipment used to construct the diversion or lake tap be
operated only in the imcediate vicinity to prevent unnecessary
damage to alpine vegetation;
5. that all waste construction materials be cleaned up and removed
after project completion;
6. that the penstock corTidor be cleared of trees and shrubs by workers
using hand tools;
7. that the ~JS survey the Crater Lake outlet in uid-Novecber to provide
the CE with a recommendation as to how far the pensto~~ and powerhouse
should be located away from the stream to pro~ect fishery resources; and
3. that the powerhouse tailrace return water to the small outlet stream
draining Crater Lake prior to entering Orca Inlet.
Humpback Creek
1. That the exact project design plans complete with all road locations,
stream crOSSings, and transmission line corridor be supplied to the
FWS as soon as they are available;
2. that the powerhouse be located immediately do~mstreac from the
deteriorated log crib dam in the lower stretch of the Hucpback Creek
canyon;
f-~.: ... 1I
3. that an energy dissipator be installed to 1>revent the tailr;lce
dischar~e from scouring the strea~bed;
4. that the trans~1saion line parallel any road cor~t~ctcd fron the
Orca canneries to the ~uth of Hu~back Creek;
5. that the transmission line be built to eli~inate ~ny possible chance
of electrocution of Lar~e raptors (bald eagles); and
6. that durL~g ccnstruc~ion, all food-related garbage be placed L~
metal containers and renovcd from the site daily to prevent a
nuisance bear situation.
Pover Creek
1. !hat the exact project design plans be supplied to the ~~s as soon
as they are available;
z. that the CE func the FWS to dete~ine monthly stream flaw requirements
for optm~ !I&lr.tonid production and survival .2!. that the CE t10ve the
pro~osec powerhouse location upatream to the and of the Power. Creek
roae;
3 that the F\-jS !'lake an add1 tiona1 stream survey in t"dd-tiovcr:mcr to
help verify spavnina areas for coho Ba~n and Dolly Varden;
4. that the tailrace be constructed to prevent scouring of the streuobed
below the po·~rhouse;
5. that the tailrace d15~,arge enter the creek in such a manner 30 as
to 3void attracting adult saln:on returning to sp.mn;
6. that during construction, all food-rcla~ed garbage be placed in
~et3l containers and recoved fr~ the site daily to ?revent a
nuisance bear situatiou; and
7. that the transmission line be buried parallel to the Pow~r Cre~~
road fr~ the powerhouse to the substation in Core ova.
HANNA:mw:jh:9/1l!80
Diskette: CORDOV
OS:6:Job C
LI'!l!:ltATURE CITED
Alaska Depart!2nt of Fish and Garne. 1973. Alaska's Uildlife and
Babitat. Edited by R. LeResche and R. llinman. 143 pp., 5630aps.
• 1978a • Alaska's Fisheries Atlas, Vol~e I. Compiled by
R. McLean and ~. Delaney. 40 pp. , 357 maps.
1978b. Alaska's Fisheries Atlas, Volume II. Compiled by
R. Mcl.ean and K. Delaney. 43 pp. , 269 caps.
CP.2M Bill. 1979. Reconnaissance study ot hydropower sites near
City of Cordova, Alaska. Submitted to Alaska District, Corps of
Engineers, Anchorage. Contract DDACl185-79-J-0019. 51 pp.
Cusey, W. 1978. The Fish and Wildlife Resources of the Gulf of Alaska.
Environmental Affairs, Shell Oil Co., Houston, !ezas. 580 pp.
,
Johnson, A. 1949. Prel~na~ report on water-power resources of
Power Creek near Cordova, Alaska. U.S. Geological Survey, unpublished
report. Tacoma, Washington. 37 pop.
HcCurdy, !1. 1919. Letter, Z!ike McCurdy, Alaska Department of Fish
and Game, Cordova, to U.S. Fish and ~lildlife Service, Anchora;e, 14
December 1979.
~tiller, D. 1951. Geology at the site of a proposed dam and reservoir
on Power Creek near Cordova, Alaska. U.S. Geolggical Survey Circular
136, 8 l'p.
Morrow, J. 1980. The Freshwater Fishes of Alaska. Alaska l;orthwest
Pub.lishing C01:1pany, Anchorage, Alaska. 243 PI'.
Pirtle, R. 1977. Historical pink and chuo salmon est~~ted spawning
escapements from Prince Willima Sound. Alaska streams, 1960-1975.
Technical Data Report No. 35. Alaska Departcent of Fish and Garne,
Juneau. 332 pp.
Raptor Research Foundation. 1975. Suggested practices for ray tor
protection on powerlines. Briaham Young University. Provo, Utah.
3 pp. and 16 plates.
Reynolds, J. 1980. Letter, Julius Reynolds? Alaska Department of
Fish and Gat::e, Cordova, to the U. S. Fish and ,-i1ldlife Service 7
Anchorage, 29 Septecber 1980.
Stalnaker, C. and J. Arnette. 1976. !lethodologias for the Dete~nation
of Stream Resource Flow Requirements: An J\ssessr.ent. Prepared for
the U.S. Fish and Wildlife Service, Office of Biological Services,
Hestem tlater Allocation by Utah State University. Logan7 Utah.
199 pp.
u.S. Department of Agriculture. 1979. Powerlinc contacts by ea~les
and other large ~irds. Rural Electrification Adcinistration,
Bulletin 61-10 (revised). i-1ashington. D.C. 7pp.
u.s. Depart~Ilt of the Interior. 1979. List of endangered and threatened
APPENDIX I. Scientific names of vegetation. mammals. birds. fish.
and marine invertebrates appearing in the text.
VEGETA.TION
Common Name
Hestern Hemlock
Sitka Spruce
Balsam Pop lar
Black Cottonwood
Sitka Alder
Devilsclub
Blueberry
Willow
!1ountain Heath
Cassiope
T..abrador Tea
Alpine Azalea
Hoss Cacpion
Mountain Avena
Bunchberry
Rockweed
Sea Lettuce
Wrack
MM1J.!ALS
Common Nace
Barbor Seal
Sea Otter
Dall Porpoise
.Mountain Goat
Sitka Black-tailed Deer
Brown Bear
Black Bear
Porcu~ine
Short-tailed Heasel
~tl.nk
Uarten
Red Squinel
Hoary }f.armot
Beaver
Huskrat
River Otter
BIRDS
Cot:mlOn ~~am.e
~1stl1ng Swan
Canada Goose
~fallard
Scientific Nace
Tsuga hetarophylla
Picea sitchensis
Populus balsamifera
Populus trichocarpa
Alnus sinuata
Oplopanax horridus
Vaccinium spp.
Salix spp.
Phyllodoce aleutica
Cassiope spp.
LedUT.l palustre
Loiseleuria Drocumbens ~~-----,.;; . .-...;;.;;.;;;;;.;;.,;;,;;;;;. Silene acaulis
Dryas inte~rifolia
Comus canadensis
Fucus sp.
Ulva aD. -. Larninaria sp.
Scientific Name
Phoca vitulina
Enhydra lutris
Phocoenoides dalli
Oreamnos americanus
Odocoileus hemionus sitkensis
Ursus arctos
Ursus arnericanus
Erethizon aorsatuo
~~ustela erminea
l-iustela vison
~~rtes americana
Tamiasciurus hudsonicus
11arI!l.ota caligata
Castor canadensis
Ondatra zibethicus
Lutra canadensis
Scientific Uame
Olor colut"lbianus _..;o.;;,=~~~
Branta canadensis
~ platyrhynchos
~ .--:J
~.:.' )
:j)":':'~.' .. ;.'< .. "' • . t
;~
Pintail
Green-winged Teal
Bufflehead
Harlequin
Scoter
Cacmon Merganser
Northern Bald Eagle
Gyrfalcon
Spruce Grouse
Ptarmigan
Black Oystercatcher
Semipalmated Plover
Spotted SaDdpiper
Greater Yellowlegs
Glaucous-winged Gull
Mew Gull
Black-legged Kittiwake
Arctic Tern
Downy lloodpecker
Ste ller I S Jay
Common Raven
Northwestern Crow
Dipper
~.)'1nter Wren
Al:nerican Robin
Varied Thrush
Hemit 'Thrush
Colden-c.rowned Kinglet
Ruby-crowned Kinglet
liater Pipit
Yellow Warbler
~lilson 's t-larbler
Savannah Sparrow
FISH
COt'lI:1On Name
Pink Salr1CJn
Sockeye Sa lmon
ChUrl Salmon
Coho SalIl10n
Chinook Salmon
Pacific Herring
Pacific Halibut
Rainbow Trout
Dolly Varden
Cutthroat Trout
Burbot
Round Whi tef1sh
}!ARlNE INVERTEBRATES
Cornmon Name
Barnacle
Bay Mussel
Anas acuta
Anas creec:a -~~..;;..;;.
Buc:ephala albeola
ilistrionic:us nistrionicus
~elanitta spp.
~ferl!us. merR~nser
F~liaeetus leucocephalus alascanus
Falco rusticolus
Canachites canadens~s
Lagopus spp.
Haematopus bach~an1
Charadrius semipalmatus
Actitis macularia
Trinqa melanoleuca
(
Larus glaucescens
Larus canus
Rissa trid.actyla
Sterna paradisaea
Picoides pubescens
Cvanocitta stelleri
Corvus corax
Corvus caurinus
Cinclus nexicanus
Troglodvtes troglodytes
Turdu8 migratorius
L"toreus naevius
Catharus guttatus
Regulus satrapa
Regulus calendula
Anthus 3Pinoletta
Dendroic:a petechia
~ilsonia pusilla
Passerculus sand~richensis
Scientific Nal!le
Oncorhynchus 5orbu5cha
Oncorhynchus neri'...a
Oncorh,,'tlchus keta . -Oncorhynchus kisutch
Oncorhynchus tshawyt3cha
elupes pallasii
Hippoglossus stenolcpsis
Salea gairdneri
Salve linus rnahla
Sal no clarki clarki
Lota Iota --Prosopiuo cylindraceum
SciaDtific Name
Balanus sp.
Uvtilus edulis <
.j> .. ' .....
-",yo
.'
Horse Clam (Caper)
Butter Clam (Washington Clam)
Littleneck Clao
Cockle
Razor Clao
Surf Clam
Pacific Scallop
Shrimp
Dungenesa Crab
King Crab
Tanner Crab
Tresus nuttallii
Saxidonus giganteus
Protothaca staminea
Cardiidae
Siliqua patula
Spisula alaskana
Patinopecten caurinus
Pandalidae
Cancer magister
Paralithodes carntschatica
Chionoecetes baird!
-62-
APPENDIX II: Drawings of Power Creek depicting the major physical
and biological characteristics from the USGS gauging
station to 0.3 mile above the end of the Power Creek
road. (Drawings compiled on 4/18/80 and updated 6/3/80 to
6/8/80).
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Valdez Interim
Southcentral Railbelt Study
Allison Lake Hydropower Project
Alaska
Final Fish and ~ildlife Coordination Act Report
Submitted to Alaska District
U.S. Army, Corps of Engineers
Anchorage, Alaska
Prepared by:
Western Alaska Ecological Services Field Office
U.S. Fish and Wildlife Service
Anchorage, Alaska
May 1980
TABLE OF CONTENTS
Page
INTRODUCTION ••••••••••••••••••••••••••••••••••••••••••••• 4
AREA DESCRIPTION ••••••••••••••••••••••••••••••••••••••••• 4
PROJECT DESCRIPTION •••••••••••••••••••••••••••••••••••••• 5
RESOURCE INVENTORy ••••••••••••••••••••••••••••••••••••••• 5
PROJECT IMPACTS •••••••••••••••••••••••••••••••••••••••••• a
DISCUSSION ............................... " ••••••••••••••••• 13
RECOMMENDATIONS •••••••••••••••••••••••••••••••••••••••••• l7
LITERATURE CITED ........................................... 20
APPENDIX A: SCIENTIFIC NAMES OF SPECIES ••••••••••••••••• 21
APPENDIX B: TEMPERATURE DATA ••••••••••••••••••••••••••• 22a
(.J
LIST OF FI~JRES AND TABLES
Page
Figure 1. Location and Vicinity Map Southcentral
Railbelt Study, Valdez Interim ••••••••••••••••••••• 4a
Figure 2. Valdez Interim Report, Southcentral
Railbelt, Allison Lake, Topographic Plan •••••••••• Sa
Figure 3. Valdez Interim Report, Southcentral
Railbelt, Allison Creek, Topographic Plan •••••••••• 5b
Figure 4. Seasonal Variation Population Density
(~ of Haroacticus uniremis •••••••••••••••••••••••••••• 7a
Figure 5. Bald Eagle Nest Sites,
September 14 and 16, 1976 •••••••••••••••••••••••••• 8a
Table I Prince William Sound Salmon Catch by
Species in Numbers of Fish, 1970-79 •••••••••••••••• 6a
Table II Value of Prince William Sound Salmon Catch
in Pounds, and Value to Fishermen, 1970-79 ••••••••• 6b
Table III Allison Creek Salmon Escapement Data ••••••••••••••• 6e
I Table IV Allison Creek -Discharge ~easurements ••••••••••••• 8b
)
I~TRODUCTION
The Alaska District, Cc=?s of Engineers (CE) is investiga~ing the
need for electrical energy at Valdez, Alaska and surrounding commu-
nities. In performance of this investigation, the CE analyzed
various alternatives and has identified the hydropower potential of
Allison Lake. A detailed feasibility analysis of this project is
occurring. :bis final Coordination Act report is being provided to
the CE by the Western Alaska Ecological Services Field Office of the
U.S. FiBh and Wildlife Service (~~S) to assist in that analysis.
AREA DESCRI?TION
Port Valdez is located in the northeasternmost extension of Prince
William Sound, and is surrounded by the Chugach ~ountains. The Port
is a steep walled, glaciated fiord which is 3 ~les wide and extends
in an east-west direction about 14 miles. At its western end the
fiord bends to the southwest and constricts to a one ~le width at
Valdez Narrows before opening into the Valdez Arm of Prince William
Sound. The steep mountain slopes/extend beneath the water, forming
a flat bottomed trough 400 to 800 feet deep. The shore of Port
Valdez is steep and rocky, except where river deltas and glaCial
moraines project into the fiord. Port Valdez is the northernmost
ice-free seaport in Alaska, and provides the shortest and most
direct route between tidewater and the interior of Alaska. The
southern terminus of both the Trans-Alaska Pipeline and the Richardson
Highway are located in Valdez.
Approximately 70 earthquakes with a magnitude of five or greater on
the Richter scale have been reported at Valdez since 1898, and seven
earthquakes have equaled or exceeded a magnitude of eight. The 1964
Alaska Earthquake and the attendant secondary impacts virtually
destroyed the original town of Valdez on the Lowe River Delta. A
new town has since been constr~cted on the delta of ~lineral Creek on
the north side of the bay.
Valdez enjoys a maritime climate, characterized by heavy preCipita-
tion and relatively mild temperatures. The average annual precipi-
tation is 59.31 inches, including 244 inches of snow. The average
annual temperature at sea level ranges from 39° to 43° F, with a
recorded maxL~um of 87° F and a minimum of minus 28° F. Local winds
are influenced by the Chugach Mountains and follow two distinct
patterns: (1) from October through ~rch or April prevailing winds
are f=om the northeast, and (2) from May through September prevail-
ing winds are from the southwest. Maximum sustained winds of 58
m.p.h. and gusts of 115 m.p.h. have been recorded at Valdez.
AlLison Lake (Figure 1) is located near the Trans-Alaska Pipeline
terminal in a glaCial cirque lying in a north-south trend. A glacial
moraine extends across the valley and bnpounds the lake at a surface
elevation of 1,367 feet. Tne lake is 1.25 miles long, approximately
0.3 ~ile wide, and over 190 feet deep. Several small glaciers and
oermanent snowfields at the head of t~e valley drain into the lake.
~ne outlet stream traverses a gentle gradient for approximately 0.6
mile before descending steeply to sea level.
l
\
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J
~ROJZCT DESCRI?T!ON
The proposed Allison Lake hydropower facility will consist of a lake
tap at 1,250 feet elevation, a rock tunnel from this level to 1,220
feet elevation, and a 48-inch penstock reaching f=om the lake tap
through the rock tunnel to one of t~e two proposed powerhouse alter-
natives (Figures 2 and 3). Both proposed powerhouse alternatives
are lOCated on Alyeska 21peline Ser~ice Company property and either
would occupy about 1.5 acres. The Alyeska terminal site road would
provide access to either site, with only an additional 50-100 feet
of road construction required.
Powerhouse alternative #1 is proposed above the existing weir in
Allison Creek, rNhich was constructed by the Alyeska Pipeline Service
Company for a partial source of water for the terminal of the Trans-
Alaska Pipeline. lne proposed powerhouse is at an approxi~te
elevation of 100 feet (Figure 2). The tailrace would run directly
into Allison Creek at this location. The CE has not proposed a dual
tailrace configuration at this site as described below for powerhouse
alternative #2; however, further consideration of such a feature at
this site is contained in the discussion section of this report.
Powerhouse alternative #2 is proposed near tidewater at an approximate
elevation of 10 feet (Figure 3). A combination of two tailraces are
proposed by the CE for this powerhouse. One would discharge directly
into Port Valdez, the other would discharge into Allison Creek near
the proposed powerhouse. CE personnel have stated that the discharge
from the proposed powerhouse could be regulated through each tailrace
independently or through each simultaneously. Fo'r example, flow
through one tailrace could be constant while flow through the other
would vary according to power generation requirements. In addition,
a six-inch steel diversion pipe is proposed from the penstock to
Allison Creek above the existing weir to provide supplemental water
if the tributary flow to the creek is not sufficient for the needs
of Alyeska. and resident and anadromous fish.
To allow disposal of the proposed spoil, excavated from the rock
tunnel, an access road approximately 500 feet long will be con-
structed from the lower end of the rock tunnel at 1,220 feet
elevation due east to the edge of a cliff. About 45,000 cubic yards
of rock is proposed to be dumped over this cliff and into a deep
gorge.
The proposed transmission line will run 3.5 miles from one of the
proposed powerhouse sites to t~e Solomon Gulch substation of the
Solomon Gulch hydropower facility, now under construction by the
Copper Valley Electric Association. It will closely follow the
route of the existing Dayville Road along Port Valdez.
RESOL~CE INVE~TORY
Lower elevations of thy!coa~tal forest in_ this :egion support dense
stands of Sitka spruce-' anu mountain hemlock ~th an understory of
~/ Common names of plant and animal species are used throughout this
report. A list of scie~ti£ic names is given in APPE~~L~ A.
ALLISON LAKE
~. .
.i.
-
..... "enor-Valdez In~er~m 0
Souchcencral Rail~~l~
A:lison Lake
TOPC"=""'D.:'; -1) e u .............. !..an
/ ;)
/" ,
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... __ / I
'l<llde'" I ~ _ I'!te"'im R
::;outhcent-ai' epot't ~ Railbelt
Al.lison C _ ::"Eek
lOpog'l"3.ph' __ ~c Plan
Figure 3
-
7
alder, salmonberry, blueberry, and devilsclub. The steep walls
above Allison Lake and upper Allison Creek support alpine tundra.
Tall shrub thickets dominated by alder and some balsam poplar occur
in the area of lower Allison Creek. The riparian area above the
lake supports mainly willow thickets.
The fresh and saltwaters of the Prince William Sound area support a
number of valuable fish species which are of great economic impor-
tance to the local economy. The short. coastal streams (approxi-
mately 700) are important for salmon production. Salmon usage of
these small streams is so widespread that, unlike other areas of
Alaska, no single stream or small group of streams plays a dominant
role in salmon production. In addition, the island-bay complex of
the Sound, provides thousands of miles of shoreline distributed in a
fiord system particularly suited to early-stage rearing of juvenile
salmon.
The Prince William Sound area has been a rather consistent salmon
producer since 1960. The average total salmon catch of 4.6 million
fish represents approximately 10 percent of the statewide salmon
harvest (Table I). The economy of the Prince William Sound area is
largely dependent on the commercial salmon fisheries (Table II).
The sport fisheries in the Prince William Sound area are also important
to the economy and are primarily centered around the communities of
Cordova, Valdez~ and Whittier. the area supports an expanding
marine fishery which is concentrated in Valdez Arm near the city of
Valdez.
Sport fishing is an important tourist attraction for Valdez and a
major source of summer recreation for local residents. Saltwater
salmon fishing is popular, with coho salmon being the most sought
after species. Pink and chum salmon are also caught in large numbers,
and a few chinook are occasionally landed. Dolly Varden, halibut,
rockfish, dungeness crab, and butter clams are also harvested in the
saltwater fishery. Freshwater fishing activity is minor in the
Valdez area. Salmon· fishing is prohibited in all streams draining
into Valdez Bay, and trout habitat and populations are limited.
No fish are known to occur in Allison Lake, but fish do inhabit the
lower 0.5 mile of Allison Creek. Fish migration above this point is
blocked by high water velocity and the steep gradient of the stream.
The weir in Allison Creek is also a partial barrier to fish migration.
Dolly Varden and sculpin are resident in the creek, while spawning
populations of adult pink and chum salmon seasonally occur in the
summer and fall. Egg development of salmon occurs through the
winter months until out-migration of fry in early spring.
Salmon escapement estimates are limited and the available data
collected between 1960 and 1971 b~ the Alaska Department of Fish and
Game (ADF&G) are given in Table III. It is apparent that escapement
counts on Allison Creek were not conducted on a regular basis;
however, numbers of chum salmon counted in 1963 exceeded 2600 and
C
I
'--.../
Table I
?rir.::e :,Jilliam Sound Salmon Catch by :>pecies, in Numbers: of fish, 1970-79.1./
Year C!1.inook Sockeye Coho Pink Chum -I Total
1970'l:.1 1,031 104,169 ll,485 2,809,996 230,661 3,157,342
1971 3,551 88,368 30,551 7,310,964 574,265 8,007,699
1972 547 197,526 1,634 54,783 45,370 299,860
1973 2,405 124,302 1,399' 2,056,878 729,839 2,915,323
1974 1,590 129,366 801 448,773 88,544 669,074
1975 2.519 189,613" 6,142 4,452,805 100,479 4,751,558
1976 1,044 ll2,309 6,171 3,018,991 370,478 3,509,493
-It 1 97i1/ 632 310,147 804 4,509.260 570,497 5,391,340
* 1978~/ 1,043 220,329 1,464 2,785,156 483,559 3,491,551
* 1979!:../ 2,002 146,468 6,780 15,375,339 323,397 15,853,986
Totals 16,364 , 1,623,597 67,231 42,822,945 3,517,089 48,04i,2.26
10 yr
Average 1,636 162,360 6,723 4,282,294 351,709 4,304,722
1/ 2/ Does not Include Copper-Bering Rivers.
Source: 1970-76, Alaska catch and production.
statistics. Statistical leaflets #21,
Commercial fisheries
23, 25, 26, 27, 28, and
29. 3/ T; Sou::ce: Alaska Department of Fish and Game, 1977, Annual Report.
Source: Pete Fridgen, Alaska Department 6f'Fish 3~d-Game, -Cordova.
* Prellminary results.
.. '. l () ~ }
,;'
'Llh I e r [
Prince William Sound S.lImLlIl C.I[ch ill PIHlllds,
------~--------'-------------_.--------------------------------_.
y i~ il r P!lllllds All Species TOld_ V:due
I'i Ilks f. Cblllllo> C:ltl::' ill llu11.lr:;
_._---_._-------
.. . I / 1 'J71l-=-I) , En J ,(' HH H'J f)4 $2,~;'7,~U~
1'171 1l ,21 7 ,(d'i ~I ~) 7
'J /
7,436,51:)-::'
197:! 2,132,51l) UI )0 L, n6,U61~/
197) 16,3 III , 1 56 70 9J
.) /
8 , tJ3 5 , U I b'::'
197'1 3,906,5117 67 7 :) ') 811 b91J~/ , ,
1975 18,524,038 Y'I n 5,7':)],6 119
1976 17,038. 1 ti9 86 95 7,395,290
19771/ (2(),432,3]7) 84 (91) data not available
1978Y (17,740,921) 80 (91 ) (6,832,242)
197~/ (68,660,829) 97 (98) (27,391,727)
1/
2/
3/
4/
5/
Source: 1970-76, Alaska catch and production. Commercial
fisheries statistics. Alaska Department of Fish and
Game. Statistical leaflets, No.'s 21, 23, 25, 26,
27, 28, and 29.
Includes value of salmon from the Copper-Bering River districts
also.
1977 data in parentheses are preliminary estimates only and not
published by the Alaska Department of Fish and Game. Total
pounds calculated using 1976 average weights for each species.
Chinook salmon not included. Source: Dennis Haanpaa, Alaska
Department of Fish and Game~ Anchorage.
1978 data in parentheses are preliminary estimates only and not
published by ADF&G. Total pounds calculated using 1976 average
weights for each species. Chinook salmon not included. Total
value of the catch calculated by using the 1978 average dollar
value per fish paid to the fishermen. Chinook salmon not
included. Source: Dennis Haanpaa, Alaska Department of Fish
and Game, Anchorage.
1979 data in parentheses are preliminary estimates only and not
published by ADF&G. Total pounds calculated using 1976 average
weights for each species. Chinook salmon not included. Total
value of the catch calculated by using the 1979 average price
per pound for each species paid to the fishermen and the 1976
average weights for each species. Chinook salmon not included.
Source: Dennis Haanpaa, Alaska Depart~ent of Fish and Game,
Anchorage.
C
1976 Average weights by species
Sockeye -7.4 1bs
Coho -8.5 Ibs
Pink -4.2 Ibs
Chum -9.1 Ibs
Source: ADF&G, 1976 catch and production. Commercial fisheries
statistics. Statistical leaflet 1129.
1978 Average price per fish paid to the fishermen
Sockeye - $
7.48/fish
Coho 3.59/fish
Pink 1.29/fish
'J Chum 3.28/fish
Source: Dennis Haanpaa, ADF&G, Anchorage
1979 Average price per pound paid to the fishermen
Sockeye - $
1.400/lb
Coho O.390/1b
Pink 0.377 lIb
Chum O.530/1b
Source: Dennis Haanpaa, ADF&G, Anchorage
II
--i
\ -.../'
., . : 1 --r • I ,I.) .. I~ 1 ... 1
All i~on Cr8ek Salcon Escapement Data
----------------_._-----------------------
0: t. "! r Escapement
Plnk' Salmon Chum Salrno~ ------
~li(,() 100
19(' L 750
L962 560 580
lOA] -0-2,660
1%4 -O~ 190
! 96 5 -0--0-
19fJ6 -0--0-
i969 500-1,000
1971 300
1973 25
Source: ADF!.G.
:<ute: AlliSvll Creek was not rl:!gularl;' checked for escapement by
ri sh ;Jnd C.,lIne bu t only ns c i::Jc <lod funding allowed. A. year which
shows zero ~~h':;lpernent ,iccs :1Ot necessarily mean th<lt no fish spawned
th.-Lt year. it on1:: inciicat02s that ~lt the time it was checked there ',.;ere
no Cisil :-,t'"l?~H:nt.
'-I I J
I;)
,· .. t (1
the number of pink salmon counted in 1969 reached 1,000. In even years
spawning by both pink and chum salmon occurs almost exclusively in
the intertidal reach of Allison Creek, an area estimated to be 40 feet
wide by 300 feet long. During odd years, when stronger runs of pinks
occur in Prince William Sound streams, spawning also occurs in
Allison Creek upstream to the existing weir.
A basic understanding of the life cycle of pink and chum salmon is
necessary to recognize all potential impacts which could occur from
the proposed project. Adult pink salmon return to their natal
streams to spawn in mid-summer or fall of their second year. Adult
chum salmon are predominantly three, four, and five, ye'ar-old fish.
Pink salmon enter streamS in the ,Valdez area in July and spawn in
August and early September, while chum salmon spawn slightly later.
Eggs are deposited in the streambed gravels'where development to
the fry stage occurs.
-Alevins (embryos which have emerged from the egg) remain in the
gravel until their yolk sacs are completely, or almost completely
absorbed. The life cycles of pink and chum salmon are very s1m:1.lar.
For chums, the alevin stage (from hatching to emergence) is completed
in 30 to 50 days, depending on the water temperature. In Port
Valdez, fry emergence of pink and chum salmon begins in mid-April
and peaks in May.
Both pink and chum salmon fry migrate to salt water during their
first summer, generally within a few days to a few weeks after
emergence. Once in salt water, the young salmon feed in schools
near shore until late July or August; some remain near shore until
autumn. Be~een mid-summer of their first year and their second
summer, they disperse throughout the offshore waters of the North
Pacific Ocean and Bering Sea.
In salt water, main foods of young pink and/or chum salmon have been
reported to be cladocerans, copepods, barnacle naupli, barnacle
cyprids, euphasids, and tunicates (Bakkala, 1970). Other studies
have shown harpacticoids to be a major' component of the stomach
contents of post-emergent pink and chum salmon fry (Kaczynski. et.
al., 1973; Healey, 1979). The seasonal population density of the
copepod Harpacticus uniremis in Port Valdez is shown in Figure 4.
Wildlife known to occur in the Allison Lake drainage include brown
bear, black bear, mountain goat, wolf, wolverine, marten, porcupine,
and snowshoe hare. Upland game birds include willow, rock, and
white-tailed ptarmigan and spruce grouse. There is little infor-
mation on the occurrence of small mammals and birds in the project
vicinity, although lists of species are available for the Valdez
area. A general list of species which may occur in the vicinity of
Allison Creek is provided in APPENDL~ A.
Waterfowl use of Allison Lake and the creek is considered quite
limited. The lake may occasionally be used for resting, and feeding
may occur in the shallow, upper part and along the braided stream
channel. Approximately 18 Canada geese have been obserled resting
·i.
".
".
I
I .. ;
I. -
I
J I
I ~,
'.
• _ I
4
(j
..........
/' ~, .•. /
----J ~.""'...-
_. o •• 1 ~ .. L .• _, ___ ~_, _1~.j._.l"""""""' ______ .l_'----1...-4-• .L~-.......-.l...· J ~_...L..-_.i_.~, . ........L........l...-~_.l.._.L-'--..... ----".~) ...... ;,=* k·-·~ _--'----...1._ ....... J.~
.. I ... ..J. :,C ..... '18 ...... 111 /lJa .... , J.-' JUl "'l~ It' OCt "-OW' ole J .................. P" ..... J".' ....... ~ St' (Ji";1 "'0 ... Ole J .............. 111 AlA w ... r
I.': ------. -I-·-------------··----•• ,j -------------t------~-------.--,,,,. ----------·--------t-----·--III. -.-----t
Seil!.iollal V3rJatlon in Population n.ensity of llarpilc_llyu~ ~E!..!!"::"~_~'
feJcr. et al .• 1976.
in the fall at the upper end of the lake by FWS personnel. Also,
molting geese were observed in the Allison Lake Basin by FWS per-
sonnel during 1979.
Extensive waterfowl use is made of the intertidal area around llpper
Port Valdez and the Lowe River Delta. Numerous seabirds inhabit
that area also. Waterfowl present in the Valdez area year-round
include scoters, goldeneye, common and red-breasted mergansers,
mallards, buffleheads, harlequins, and Canada geese. Others sea-
sonally present in the Valdez area include pintails, teals, wigeons,
oldsquaws, and shovelers.
Northern bald eagles are common in the Valdez area. Personnel of
the FWS conducted a survey in 1976, locating 23 eagles and 10 nests
within ?ort Valdez (includes all of the shoreline inside of Middle
Rock except for the Lowe River flats south of old Valdez). Two
nests were identified within three miles on the mouth of Allison
Creek, one on each side of the stream (see Figure 5). Congregations
of eagles are attracted by salmon to mouths of stream which flow
into ?ort Valdez. The carcasses of salmon are an important addition
to the diet of both resident and migratory eagles. Other raptors
found in the Valdez area include the osprey, red-tailed hawk, sharp-
shinned hawk, goshawk, and Peale's peregine falcon.
No terrestrial threatened or endangered species are known to occur
1n the Valdez area. The endangered finback and humpback whales have
been sited in ?ort Valdez. Peale's peregrine falcon is not listed
as an endangered species under the Endangered Species Act of 1973.
Hunting, hiking, and overnight recreational use in the Allison Lake
area appear to be limited, due to the rugged terrain. However, a
rough hiking trail to the lake is presently used by local residents.
Port Valdez is used, or occasionally visited, by the following
marine mammals: northern fur seal, harbor seal, sea otter, northern
sea lion, killer whale, humpback whale, Oall's porpoise, and harbor
porpoise. The nearshore area from 0.3 mile west of Allison Creek to
0.3 mile west of Dayville Flats Creek has been identified as a
feeding area for sea otters and harbor seals.
The flow regime of Allison Creek varies from high flow in early
summer and fall to low flow in the late winter and early spring.
Specific data are lacking and that data available is given in Table
IV.
PROJECT IMPACTS
Impacts which would result from the project are discussed in two
categories: construction, and operation and maintenance.
Construction: At present, no access road is planned to Allison
Lake. This considerably reduces the possible impacts of the project
on the upland area. The road and rock dump associated wi!h the
tunnel construction will cover existing vegetation, as well as
create a scar visible from Valdez. Weathering of the rock will
Fi.gu::-e
)
-,
SaId Eagle ~esc Sites, Sepcember
_. ,
,-, .
--;.-..... ---
L
I~; S '7
'-.._-
36
D £' Z
. Ii"';
If'
';
1 ' 1..4 :6,
\ ;1
\ \ • i
19i5 ..
: ,Min ... , ChIM' .:" .. ,
ISla""1 -.'
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i
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,
• ! , .... _ ... __ .. _.
. I~'
.1
17
72~~~ IV Allis2~ Creak -~is~~arge Measurements
') -·'):-50
l.-2 3-7 ~
2-i2-74
2-2]-74
3-15-7'-
4-09-74
t, -2 3-7!,
11-13-7':'
lZ-17-7i,
1-25-75
2-07 -is
2.-19-75
3-06-75
3-07-75
3-~3-iS
3-17-75
3-20-75
3-23-75
'.-11-75
.:.-'7-7S
4-;:'",-75
4-25-7 5
5-01-75
6-05-75
6-12-75
4-01-76
4-02-76
4-03-76
1.,.-04-76
4-05-76
4-06-76
4-07-76
4-08-76
4-09-76
4-10-76
4-11-76
4-12-76
':'-13-76
4-14-7fj
4-15-76
Data collect~d
F:ow in cubic feet
?cr second (c.:.s.)
by:
5'-.9
11. 9
15.2
7.6
10.9
13.2
12.9
:0.4
20.2
! ") , .-
7 . 7
10.3
5.15
6. i
S.l
3.96
, ...
'"'" . "
6.0
7.0
iO.r)
4.6
5.1
5.8
85.0
Sll.O
3.9
!, ") ......
4. 7
4.9
4.6
4.5
3.3
3.9
3.9
4. 7
5.1
4.4
5.5
4.5
! ") ..... ..:..
u.s. Geological Survey
~ur:::-:~Jest Hydraulic Consultants, Ltd.
jF~';A~, Gel.)rge Perkins
l::l!Or :\135\.:.;)" Inc.
occur, and may allow the rock to blend in with the surroundings
within several years. Blasting for tunnel construction could
temporarily disturb resident wildlife. The above ground portion of
the penstock will be a permanent scar on the hillside.
Increased erosion and subsequent stream sedimentation may result
from cleared areas. The extent of this occurrence will be directly
related to construction techniques and can be avoided. Adverse
impacts which can occur to aquatic species as a result of siltation
are numerous and well documented. Major impacts from siltation, as a
result of construction of the proposed project, include decreased
vigor or death of incub~ting salmon eggs by interfering with or
preventing respiration, loss of spawning gravels, and physical
disturbance to both adult salmon and other resident species.
Clearing of approximately 2l.j acres of vegetation would be required
for the transmission line. Visual impact would be significant.
Clearing and construction activities could disturb nesting eagles
which may result in desertion of eggs and young. Bird collisions
with power lines will result in mortality. Transmission poles could
be the tallest object in the immediate vicinity and may commonly be
used by rap tors as a perch. Improper line spacing presents the
hazard of electrocution to large raptors.
Construction activities will disturb terrestrial wildlife and may
cause avoidance of the area while construction is occuring. This
impact should be minor as no wild:ife concentrations or critical
habitat areas are known to occur in the bmmediate area.
To prevent debris from reaching the turbines, construction of a
screen over the penstock intake at the lake will be necessary and
could require lake dra~down to the lake tap inlet. This will result
in dewatering the upper reaches of Allison Creek. If discharge did
not occur directly to Port Valdez or occur in a carefully controlled
manner it could create excessive discharge into the lower stream;
possible scouring of the streambed; and depending when this occurred,
above normal stream velocities could either ~revent returning adults
from entering the stream or expose incubating eggs. Also, resident
Dolly Varden could be flushed out of the system to marine waters.
Operation and Maintenance: Dur~ng projec~ opera~ion, the lake level
would be drawn down as much as 100 feet, primarily over the winter
months. Biological impacts to the lake resulting from this drawdown
would probably be minor, although the aesthetic impact would be
significant. Fortunately, the lake itself is not visible from the
town of Valdez. Fluctuating lake levels could cause lake shore
erosion leading to landslides in steeper areas with accompanying
habitat degradation. During winter, shelf ice formed by the
dropping lake level could impede movement of mountain goats. The
low number of goats in the area reduces the extent of this occurrence.
The impacts 'Nhich would result from project operation have the
greatest potential for adversely affecting the environment of
Allison Creek. The drawdown would dewater Allison Creek at its
o
'J r.
/ I
outlet from the lake; however, the CE expects natural seepage through
glacial deposits' to provide some flow into the upper creek. Also,
tributary flow will provide some stream flow to lower portions of
the creek.
Water for hydropower production would be drawn from deep in the lake
and, based upon available information, will be warmer than Allison
Creek water in the winter and colder than the stream's water in the
summer. Water at lake tap depth may also be deficient in dissolved
oxygen. A minimum dissolved oxygen concentration of 6.0 milligrams
per liter (mg/l) has been recommended for coldwater f.ish (Doudoroff
and Shumway, 1966). At the present time, dissolved oxygen data at
the depth of the proposed lake tap is not available. The passage of
water through the powerhouse and energy dissipator is expected to
aerate these waters, although the extent of this occurrence in
relation to the acceptable limits for fish is not known at present.
Temperature has a major influence on the freshwater stages of salmon.
Stream temperature data for Allison Creek has been collected by the
U.S. Geological Survey and is now being collected by the ADF&G
(APPENDIX B). The CE has also collected some temperature data for
Allison Lake (APPENDIX B). The ADF&G has also taken intertidal
temperatures at Solomon Cr,eek (three mi.les to the east) since
September, 1979, and this data would probably be consistent with
salt water temperatures off the mouth of Allison Creek (APPENDIX B).
No intragravel temperatures have been taken.
The effects of warm water discharges on developing eggs and alevins
have been studied in laboratory situations and at most major hatchery
facilities. Increased mortality and abnormal embryonic development
have been shown to occur if the initial incubation temperatures for
developing pink salmon eggs is 4.5°C or lower. At 2.0°C or lower,
complete mortality will occur (Bailey and Evans, 1971). Preliminary
temperature data from the lake (APPENDIX B) indicates that the water
through the powerplant would be 4°C or less. Based upon these data,
the potential alteration of the temperature regime in Allison Creek
could have a significant adverse impact upon the fish resources of
Allison Creek.
Low concentrations of dissolved oxygen and exposure to light can
increase incubation time, bU1: tempera1:ure is the primary factor in
regulating the duration and timing of incubation and hatching.
Oevelopment is normally expressed in terms of temperature units. A
temperature unit is defined as one degree above freezing for a
period of 24 hours. A given number of temperature units is required
for the eggs to hatch. The number of temperature units required is
generally specific to the species of fish and even to the particular
stock. Hatching and emergence is delayed in colder water temperatures
and accelerated in warmer temperatures. A minor temperature increase
or decrease could considerably advance or delay hatching. A change
in the natural temperature regime of Allison Creek could change the
timing of pink and chum salmon fry emergence. The extent of this
impact is difficult to assess with the data available; however,
significant early development of eggs would result in early
\
:~
2mergence and outmigration of Erv to Port Valdez at a ti~e when it
is questionable that there would be adequate planktonic production
to sustain rearing activity. Consequently, a substantial alteration
in natural water temperature during the egg to fry development
period would negatively impact run strength.
With sufficient data, the number of temperature units required for
eggs to hatch under natural stream temperatures can be calculated
and compared to the number of temperature units anticipated to exist
under altered stream conditions. The difference in temperature
units will show if early or late emergence will occur, and if so,
give the approximate magnitude of change in the time of emergence.
!Jhere inter~idal spawning occurs, such as in Allison Creek, the
warmer saltwater contributes to higher intragravel temperatures.
This adds to the complexity of the temperature regime in intertidal
areas because intertidal zone temperatures are influenced by (1)
upstream water temperatures, (2) saltwater temperatures exposed to
stream gravel, (3) time of e."'Cposure to saltwater, and possibly (4)
the permeability of gravels.
Should early fry emergence occur, sufficient food sources may not
exist. Figure 4 illustrates the seasonal variation in population
density of the copepod, Harpacticus uniremis, an organism which
could be an important food source for post-emergent fry. Healey
(1979) found that H. uniremis made up 50% of the overall diet of
juvenile chum salmon in the ~anaimo Estuary and greater than 80%
of the diet when fry were most abundant. He also found that
the seasonal pattern of abundance of fry and!. uniremis in the
estuary was the same, and that fry consumed most of the estimated
production of H. uniremis. Large numbers of this copepod are usually
not present In-Port Valdez until mid-~rch to early April. Under
natural conditions pink and chum salmon fry emergence begins in
mid-April in the Port Valdez area.
Radical fluctuations in stream flow contribute most heavily to
mortality of developing eggs through erosion, shifting of gravel, or
dewatering of spawning beds. Flooding also causes mortality by
depos ition of sil t on spawning areas, which slows intragravel water
movement, decreasing the oxygen supply to the eggs, and preventing
removal of waste products. Other factors contributing to mortality
of eggs are freezing, exposure to light, parasites, predation, high
salinity, shock, and superimposition of redds (spawning beds).
The tailrace discharge could cause increased velocity in the stream
and scouring of the streambed with subsequent removal or burial of
spawning gravel. Alterations in naturalstream:low could also have
adverse impacts upon spawning adults as a result of either high or
low flows which are not optim~ for spawning. Post-project flow
schedules could be beneficial to fish resources by reducing radical
flow fluctuations and providing flows optimum for life stage require-
ments of pink and ch~m sal~on.
2'
As stated previously, two alternative sites have ~een proposed for
the powerhouse. Either site ~ould require clearing of approximately
1.5 acres for construction ?urposes. Some alteration of the stream-
bank and streambed will result from installation of the tailrace and
sedimentation could occur. The magnitude of these impacts could be
reduced significantly depending on the construction techniques
utilized and the time of ';,lark.
Impacts which would result from either of the proposed powerhouse
alternatives wer2 described above. Those impacts which would vary,
depending on the site selected, are described below.
Powerhouse Alternative 41: The discharge of flow from this alter-
native is proposed by the CE directly from the tailrace into Allison
Creek. Radical flow changes would result and all adverse impacts
described previously for alteration of flow would occur. In addition,
if instream flows were totally dependent on power generation needs,
periods of very low flow could result when the power plant was shut
down for maintenance or other reasons.
The discharge of all project flows into Allison Creek at this site
would also result in temperature and possibly dissolved oxygen-
impacts occurring in the total reach of Allison Creek utilized by
fish. Flows in the creek above this site may not have any appre-
ciable buffering effect for maintenance of natural water quality
since they would be low in relation to the flow through the power-
house.
Powerhouse Alternative #2: Impacts described above for site U1 ~y
also be applicable to this afternative. This alternative has two
tailraces proposed. If the tailrace waters were discharged directly
into Port Valdez during the summer months, a portion of the salmon
population could be diverted away from spawning areas in the natural
stream by the larger quantities of Allison Creek water issuing from
the tailrace into Port Valdez. Diverting water from the powerhouse
through the tailrace positioned in Allison Creek would alleviate
this impact; however, those impacts discussed above under powerhouse
#1 would occur. ~fuen the discharge is diverted back through the
tailrace into Port Valdez, some of the redds could be dewatered.
Also. the discharge could prove to be such an attractant to adult
salmon that they would pool up below the discharge and not utilize
other portions of the stream or intertidal area for spawning.
Periods of very low flow during powerhouse shut down could also
result from this alternative. The proposed 6 inch diversion pipe
could be used to add supplemental water to the creek. However, the
use of the diversion pipe for long periods to supply water to the
stream or as a substantial supplement to natural flows could also
cause early fry emergence as dicussed earlier.
Diversion of flows directly into Port Valdez during most of the year
· .. ould result in a reduction of '.ater velocity in the natural s tream-
bed lo1hich could result in sedimenta t':'on of the spawning gravel.
( ... : .;;;,1· ;p
Should a major earthqu'ike occur, this site could be severely damaged
or ciest=oyed by seismic sea waves.
DISCUSSION
~ith fossil fuel prices continuing on an upward spiral, increasing
attention is being given to alter-native energy sources. In Alaska,
with steep slopes and abundant streams. hydropower is a logical
choice. Sites with large hydropower potential close to population
centers are limited, but potential small hydropower sites are numerous •
. Uaska also has abundant fish resources, which frequently inhabit
the same drainage systems suitable for hydropower development.
Unfor~unately, these two resources may not be completely ~ompatible.
Allison Creek, cumulatively with the other short coastal streams of
Prince William Sound, provides an important contribution to the
overall sal~on production of the area. Both the commercial and
sport fisheries play an important role i:1 the economy of Valdez. In
addition, maintenance of natural and TNild stocks of salmon in
Allison Creek can be vieTNed as an aesthetic value which cannot be
measured in rnoneta~J terms.
The most significant impacts upon fish and 'Jildlife resources which
would occur from construction of the Allison Lake project are the
~otential changes in the flow and temperature regimes of the creek.
All other potential impacts are ~onsidered less significant. An
analysis of ~~i5ting data and subsequent impacts indicate that
appropriate structural and non-structural features to mitigate major
adverse impacts could be incorporated into project design including
either of the proposed powerhouse sites which would make the proposal
acceptable environmentally. However, baseline data gaps presently
exist which preclude a complete assessment of potential impacts.
Execution of appropriate studies before or during the advanced
engineering and design stage of planning will enable a thorough
evaluation of potential impacts to fish and ~~ldlife and refinement/
development of necessary mitigation features. In addition to these
studies, a cooperative study jointly seoped by the FWS and CE, and
conducted through project construction and operation, would enable
refineme:1t of mitigation recommendations; assessment of the accuracy
and effectiveness of those recommendations; and provide a comprehensive
data base useful in the future planning of similar projects.
Available data suggests that ?eaking 0= excess flow should be
discharged directly to Port Valdez year round and that regulated
flows be discha=ged through the tailrace to Allison Creek. A
pre-project instream flow analysis of Allison Creek is needed to
derive accurate and specific optimum flow recommendaticns for fish
maintenance. The regulated flows would va~r according to life stage
requirements of fish and natural streambed flow. For example, from
approximately ~d-July to early Septa~ber adult salmon are present
in the creek and a cons~ant flow optimum for spawning should occur
in Allison Creek. Peaking or excess flow would continue directly to
Port Valdez and thi.s discharge should occur sub tidally to at least
-10 feet mean :ower low water f~om June through September to eliminate
attracting adults.
Discharge measurements are sparse and, according to the CE, accurate
predictions of the amount of water flowing through the powerhouse
cannot yet be determined. Daily discharge measurements of Allison
Creek should be taken for a minimum of one year, beginning as soon
as possible •. However, collection of data for two years or more is
recommended. These data should be provided to the FWS quarterly to
assist in refining discharge flow schedules through the proposed
powerhouse to Allison Creek.
The CE has stated that tributary and groundwater flow to Allison
Creek will contribute seasonally to base flow in the creek after
project operation. The specific amount of this flow is needed for
analysis in the development of flow recommendations to Allison Creek
from the powerhouse. The CE expects that tributary and groundwater
flow will maintain adequate flow in that reach of the stream below
the weir; however, during the low flow period of late winter and
early spring it may be necessary to supplement instream flow below
the weir to S.O cubic feet per second (cfs). The proposed 6 inch
dIversion pipe should be adequate to accomplish this.
Temperature profile data of Allison Creek is needed to assess
impacts. The CE should conduct temperature profiles in Allison Lake
to the proposed lake tap intake depth for a period of one year
beginning as soon as possible. A minimum sampling effort should
include the months of March, June, September, and December.
Concurrently, water samples for testing dissolved oxygen, pH, heavy
metal, and turbidity levels, should also be taken at the surface and
at the same depth and general location of the proposed lake tap. !t
may be feasible for the CE to :nodel or accurately predict the thermal
regime of Allison Lake with data available for similar alpine lakes.
!f dissolved oyxgen concentrations are below 6.0 mg/l, corrective
measures may be necessary if the dissipators do not insure dissolved
oxygen readings of 6.0 mg/l or above. A temperature probe or similar
recording device should be installed in the gravel where intertidal
spawning occurs to record intragravel temperature for the same time
period. The thermograph now installed in Allison Creek should also
be maintained throughout the same one-year period.
With knowledge of the existing temperature regime for Allison Creek,
the temperature of the water coming from the powerplant, the anti-
cipated base flow, and the anticipated flow schedules for project
operation, the temperature in the spawning beds could be predicted
and the effects on developing salmon embryos calculated. Until the
extent of adverse impacts can be identified, it is difficult to
predict if any other form of mitigation may be appropriate. !t
could be determined that regulation of the thermal regime of Allison
Creek may be required to protect fish resources.
During the first year of project operations, daily temperature
readings should be taken in Allison Creek below the tailrace dis-
charge and provided monthly to the ~NS and the ADF&G. Depending on
the temperatures, it ~y be feasible that refinement of discharge
recommendations could further mitigate potential impacts due to
I. I
' . ..-/
alteration of the temperature regime through ~~ng base flows in
Allison Creek with project flows. An extension of the one year
recording period may be necessarJ.
As additional information is a"ailable for a thorough assessment of
impacts due to poterttial changes in flow and temperature regimes,
other alternatives for the discharge to Port Valdez :nay be acceptable
or recommended. For example: (1) operation of the project only for
base load power production would eliminate the radical flow variations
associated with a peaking facility, (2) alterations in the discharge
of flow from the tailrace in response to power demand could be done
incrementally by a specified discharge in a gi'len time period (ex.
10 cfs/hour), (3) discharge of excess flows directly into Port
Valdez could be done via a flume or manmade channel and discharged
sub tidally only from June through September.
Recent information on spawning populations in Allison Creek is also
lacking. Beginning in 1980, escapement counts should be taken at
least once a month in July, August, and September of each year.
These surveys should continue through the planning, construction,
and operation phase of the project to allow assessment of project
impacts upon salmon populations.
A dual tailrace design as proposed for the lower powerhouse alterna-
tive should be included in plans for the upper powerhouse alter-
native as well. The impacts associated with the potential changes
to flow and temperature regimes described previously would occur at
either powerhouse alternative unless appropriate mitigation features
are incorporated into project design. In fact, construction and
operation of the upper powerhouse with the dual tailrace feature is
favored slightly because stabilizing the flows in that stream reach
between the lower and upper site would benefit fish resources in a
greater portion of their habitat.
To prevent scouring and downstream sedimentation, energy dissipators
should be installed in both the tailrace and outlet of the 6 inch
diversion pipe to Allison Creek. Design of the dissipators should
insure that the velocity of the discharge into ~lison Creek will
not exceed the optimum velocity of the natural s~ream for fish
maintenance.
The timing of construction will be of considerable importance in
minimizing impacts to fish. The work should be done to avoid cri-
tical biological life stages. Disturbance of the water quality or
streambed morphology while eggs are incubating or fry arz emerging
can result in direct mortality through suffocation by burial or
ph;1sical damage. Disturbance ,.hile adults are present can disrupt
or prevent spawning and limit production of future generations. The
timing of any inwater construction activity or construction on the
banks of Allison Creek should be coordi:1ated ·,.,i th the n-lS, ~ia tional
Marine Fisheries Ser.,rice (i:iHFS) ,and the A.DF&G to avoid unnecessary
impact on the salmen population. Also, because highest densities of
?opulations of spawning salmon occur in cdd years, major const=uction
affecting flows should be done on even years.
,.
I Ij
;r
Streambed sedimentation can be caused ~y a variety of activities.
Improper construction and cleari~g techniques can cause increased
runoff and excessive erosion. Clearing for penstock construction
above ground should be limited to large shrubs and any trees "4'hich
may be encountered to reduce ground disturbance and erosion. A
damaged streambank is unstable and can cause sedimentation.
Streambanks should be restored to ?re-project integrity during the
construction season in "4'hich they are damaged. Transmission line
construction should be initiated after the ground is frozen and some
snow cover exists to minimize erosion and ruttir:g.
Alteration of the streambed or barriers in the channel can cause
scouring and downstream sedimentation. Vegetation and debris should
be kept out of Allison Creek and any streams crossed by the t~ans
mission line. Any structures placed in or across streams or "4'ater-
bodies, as a result of project work, should be removed before the
end of the current construction season. An erosion control plan and
a plan for any instream "4'ork (including transmission lines) should
be developed prior to construction and presented for review by
resource agencies to insure appropriate precautions are implemented.
Care should be taken to prevent the introduction of toxic materials
into any waterbody. Fuels, lubricants, and other potential pollutants
should be stored in leakproor containers within an area surrounded
by a containment berm at a minimum of 300 feet from any stream or
waterbody.
Improper disposal of refuse can serve as an attractant to bears and
other wildlife and lead to bear/human confrontations, usually
resulting in removal or destruction of the bear. Feeding of wild-
life by construction crews is illegal and should not be allowed.
During construction, all refuse should be placed in metal containers
with heavy lids and be removed from the site regularly.
Nesting eagles can easily be disturbed by human activity which may
cause them to desert eggs or young as a result. Nest removal or
disturbance of bald eagles is prohibited by the Bald Eagle Act of
1940. When the exact transmission line route i~ established, ~NS
personnel should be given the opportunity to survey the route for
any nests. Restrictions may be placed on construction activity
occurring between April 1 and July 15 if nests are found in close
proximity.
Improper spacing of transmission lines can cause electrocution of
raptors. Transmission line design and construction should be governed
by "Suggested Practices for Raptor !?rotection on Pm.,erlines," Raptor
Research Foundation, 1975. Use or this information should be made
to design the powerline "4'ith proper groundIng, spacing, and configura-
~ion, such that it will prevent the electrocution of raptors.
Clearing for the transmission line could create a visually displeasing
scar on the landscape. ~o lessen this impact, clearing for the
right-of-way should be li~ited to that needed to string the conductors
and allow the passage of ~onstruction equipment. To further reduce
visual impacts. small shrubs should be left in the right-of-way and
along the edge of clearings so the vegeta~icn ~ill blend ~ith the
natural surroundings.
... .. J~,
Y
It is our intent to protect the axisting salmon runs of Allison
Creek. Should we be unsuccessful in adequately protecting those
resources, other mitigation measures such as providing artificial
hatching, spawning, and/or rearing areas ~ay be determined necessary.
A final analysis to determine whether or not any of these mitigation
measures would be acceptable or are favored cannot be made with data
now available. However, based upon present flow and temperature
data, we have tenatively determined that excess flows from the
powerhouse should be discharged directly to Port Valdez to mitigate
potential adverse impacts to fish resources.
Additional data needs which have been identified should be satisfied"
as soon as possible. Those studies are: a comprehensive analysis
of the pre-and post-project temperature regimes, saliIlon escapement
surveys, bald eagle nest sur~eys, and an instream flow assessment.
These studies should be conducted cooperatively by the FWS and CEo
S:tecution of these studies would satisfy data needs for refinement/
development of mitigation recommendations and provide data needed
for preparation of a supplement to this report. A cooperative study
through project construction and operation would allow further
refinement of mitigation recommendations, assessment of the accuracy
and effectiveness of these recommendations, and proviae baseline
data for use in the planning of similar projects in the future. AD
amended scope of work and associated transfer of funds to the FWS
would be required.
RECOMMErmATIONS
1. That the design of the powerhouse allow the release of
regulated flows to Allison Creek through the tailrace and
eXcess flows to Port Valdez through the other tailrace.
2. That flows from the powerhouse tailrace to Port Valdez be
discharged subtidally to at least -10 feet MLLW from June
through September.
3. That the proposed start-up of project operation affecting
the natural flows in Allison Creek occur in an even year.
4. That the timing of proposed construction activities in or
on the banks of Allison Creek be coordinated with the FWS,
NMFS,and the ADF&G.
5. That streambanks be restored to pre-project integrity
during the construction season in which they are damaged
and debris or vegetation be kept out of streams.
6. That any structures placed in or across streams be =emoved
during the same construction season.
7. That clearing for the penstock construction be limited to
large shrubs and any trees which may be encountered •
!7
8. That during the construction phase, bulk fuels, lubricants,
and other potential pollutants be stored in leakproof
containers within an area surrounded ~y a containment berm
at a minimum of 300 feet from any stream or water body.
9. That no feeding of wildlife occur and all refuse be placed
in metal containers with heavy lids and removed regularly.
10. That transmission line construction be governed by
"Suggested ?rc.ctices for Raptor Protection on Powerlines,"
Raptor Research Foundation, 1975.
11. That clearing for the transmission line right-of-way ce
limited to only that area needed for construction and be
reduced by leaving shrubs and blending the edges of the
clearing with the surrounding vegetation.
12. That an erosion control plan and instream work plan be
prepared and made available to resource agencies for
review and comment before construction.
13. That the CE collect natural discharge data of Allison
Creek continuosly for at least one year, beginning as soon
as possible.
14. That the CE maintain the thermograph in Allison Creek to
collect natural temperature data continuously during the
one year period that other temperature data is recorded.
15. That the CE collect intragravel temperature data of Allison
Creek continuously for at least one year, beginning as
soon as possible.
16. Tnat the CE take temperature profiles of Allison Lake to
the lake tap depth and temperature, dissolved oxygen,
turbidity, heavy metal, and pH readings at the lake surface
as well as the depth of the lake tap. These measurements
should be collected as soon as possible. A minimum sampling
effort would include the months of March, June, September,
and December.
17. That the CE collect continuous temperature data below the
proposed tailrace into Allison Creek for at least the
first year of project operation.
18. That the CE determine the base flow in Allison Creek
expected above the powerhouse after project operation.
19. That prOVisions be included in advanced project planning
for the r~S to survey the selected transmission line route
for eagle nests.
20. That provisions be included in advanced ?roject planning
for escapement surveys of salmon in Allison Creek by the
ffilS or ADF&G.
21. That prov~s~ons be made in advanced project planning for
instream flow analysis of Allison Creek by the FWS to
determine optimum flow schedules and the velocity of
supplemental flows to Allison Creek.
?? _ .....
23.
That a cooperative study of the proposed Allison Creek
Hydropower project, jointly scoped by the CE and FWS and
funded by the CE, be conducted through project construction
and operation.
That, if after execution of the recommended additional
studies, it is determined that some losses to fish and
wildlife are unavoidable, those losses be offset by
implementation of mitigation measures mutually acceptable
to the FWS and the CEo
"., !J
1'1
LITERATURE CITED
Bailey, Jack E., and Dale R. Evans. 1971. The low-temperature
threshold for pink salmon eggs in relation to a proposed hydro-
electric installation. Fishery Bulletin 69(3): 595-613.
Bakkala, Richard G. 1970. Synopsis of biological data on the
chum salmon Oncorhvnchus keta (Walbaum) 1972. FAO Fisheries
Synopsis No. 41, Circular 315, U.S. Department of the Interior,
Washington, D.C.
Doudoroff, Peter and Dean L. Shumway. 1966. Dissolved oxygen
criteria for the protection of fish. American Fisheries Sociey,
Special Publication ~o. 4, A symposium on Water Quality Criteria
to Protect Aquatic Life.
Feder, Howard M., L. Michael Cheek, Patrick Flanagan, Stephen
C. Jewett, Mary R. Johnston, A.S. Naidu, Stephen A. Norrell,
A.J. Paul, ArIa Scarborough, and David Shaw. 1976. The sediment
environment of Port Valdez, Alaska: the effect of oil on this
ecosystem. For: Corvallis Environmental Research Laboratory,
U.S. Environmental Protection Agency. Corvallis, Oregon.
Healey, M.C., 1979. Detritus and juvenile salmon production in the
Nanaimo Estuary: I. Production and feeding rates of juvenile
chum salmon (Oncorhvnchus ~). J. Fish. Res. Board Can. 36:
488-496.
Kaczynski, V. W., R. J. Feller, and J. Clayton. 1973. Trophic
analysis of juvenile pink and chum salmon (Oncorhynchus gorbuscha
and O. keta) in Puget Sound. J. Fish. Res. Board Can. 30:
1003-10OS:-
/J
3u
APPENDIX A: SCIENTIFIC NM1ES OF SPECIES
Plants
Sitka spruce -Picea sitchensis
~ountain hemlock -Tsuga mertensiana
Balsam poplar -Populu; balsamifera
Willow -Salix spp.
Alder -Alnus spp.
Salmonberry -Rubus spectabilis
Devils club -Oplopanax horridus
Blueberry -Vaccinium spp.
Animals
Invertebrates
Dungeness crab -Cancer magister
Butter clam -Saxidomus spp.
Copepod -Harpacticus uniremis
Fish
Pink salmon -Oncorhynchus gorbuscha
Chum salmon -Oncorhynchus ~
Coho salmon -Oncorhvnchus kisutch
Sockeye salmon -Oncorhynchus nerka
Chinook salmon -Oncorhynchus tshawvtscha
Dolly Varden -Salvelin~s malma
Trout -Salmo ~.
Rockfish -Sebastes spp.
Sculpin -Cottus spp.
Halibut -Hiopoglossus spp.
Birds
Canada goose -Branta canadensis
Mallard -~ olatyrhvnchos
Pintail -Anas acuta
Green-winged teal -Anas crecca
~~erican wigeon -Anas americana
~orthern shoveler ~atula clypeata
Goldeneye -Bucephala spp.
Bufflehead -Buceohala albeola
Oldsquaw -Clangula hyemalis
HarlequIn -Hlstrionicus histrionicus
Surf scater -Melanitta oerspicillata
clack seater -Oidemia ~igra
Common merganser -Mergus merzanser
R.ed-breasted merganser -Mergus se!"!'ator
Goshawk -AcciDiter ge~tllis
. ' I
Shary-shinned hawk -Accipiter s triatus.
Red-tailed hawk -Buteo jamaicensis
Northern· bald eagle -Haliaeetus leucocenhalus alascanus
Osprey -Pandion haliaetus
Peale's peregrine falcon -Falco peregrinus pealei
Spruce grouse -Canachites canadensis
Willow ptarmigan -Lagonus lagonus
Rock ptarmigan -Lagopus mutus
White-tailed ptarmigan -Lagopus leucurus
Mammals
Black bear -Ursus americanus
Brown bear -Ursus arctos
Wolverine -Gulo luscus
Marten -Martes americana
Short-tailed weasel -~ustela erminea
~ink -Mustela vison
River otter -Lutra canadensis
Lynx-Lynx canadensis
Coyote -Canis latrans
Gray wolf -Canis lupus
Porcupine -Erethizon dorsa tum
Snowshoe hare -Lepus americanus
Mountain goat -Oreamnos americanus
Marine Mammals
Sea otter -Enhydra lutris
Northern sea lion -Eumetonias jubata
Northern fur seal -Callorhinus ursinus
Harbor seal -Phoca vitulina
Killer Whale -Orcinus rectininna
Harbor porpoise -Phocoena phocoena
Dall's porpoise -Phocoenoides dalli
Humpback whale -Megantera novaeangliae
~ 1 ..0/
APPENDIX B
TEMPERATURE DATA
(~
\ ,
13
Date
09/23/71
02/15/72
. OS/23/72
. 07/24/72
10/12/72
04/04/73
06/17/73
Allison Creek Temperature Data
Source: U.S. Geological Survey
Temperature b C
5 .. 0
1.0
3.0
7.0
2.5
2.5
4.0
ThermogTaph ReEl_dings
ALLISON CREEK
I~
\
'·": •• Jl!/II'/ June 1979 Ju1v 1979 August 1979
0 C
High Low Aver. High Low. Aver. High Low Aver.
Temp. Temp. TemE· Temp. Temp. Temp. Temp. Temp. TemE·
1 5 3 4 9 7 8
2 6 4 5 10 7 8.5
3 6 4 5 11 8 9.5
4 6 4 5 10 7 8.5
5 4 10 7 8.5
6 4 9 7 8
7 5 4 4.5 9 7 8
8 5 4 4.5 9 7 8
9 6 4 5 8 7 7.5
10 6 5 5.5 8 7 7.5
11 6 5 5.5 8 7 7.5
12 6 5 5.5 8 6-7
13 6 4 5 8 6 7
14 5 8 7 7.5
15 ., 5 5.5 7
".J
16 6 5 5-.5 6
17 7 5 6 6
18 7 6 6.5 6 5 5.5
19 8 6 7 6
20 7 5 6 7 5 6
21 7 5 6 8 5 6.5
22 7 5 6 7 6 6.5_
23 7 5 6 8 6 7
24 8 7 7.5 9 7 8
25 8 6 7 9 7 8
26 3 8 5 6.5 9 7 8
27 3 7 5 6-7
28 3 8 6 7 9 7 8
29 4 3 3.5 9 6 7.5 9 7 8
30 5 3 4 9 7 8 8 7 7.5 ----------
Source: Alaska Department of F-ish and Game.
ALLISON CREEK
-,
I September 1979 October 1979 November 1979 \J
CO
High Low Aver. High Low Aver. High Low Aver.
TemE· Temo. Temo. Temo. Temo. Temo. Temo. Temo. Temo,
1 5.5 3.5
2 8 6 7 5.5 3.5
3 8 5 6.5 5.5 3 2 2.5
4 9 7 8 5.5 2 1 1.5
5 7 6 6.5 5.5 1
6 7 6 6.5 5.5 2 0 1
7 7 5 6 5 2 1 1.5
8 8 6 7 6 5 5.5 3 2 2.5
9 8 6 7 5.5 3
10 7 6 6.5 5.5 3 2 2.5
11 8 6 7 5.5 2
12 9 7 8 5.5 3
13 9 8 8.5 5 2.5
14 9 8 8.5 5 4 4.5 3 2 2.5
15 8 7 7.5 5 4 4.5 2
16 7 5 2 1 1.5
17 7 5 4 4.5 1
.~ 18 7 4 0
19 4 1 0 0,5
20 3 1
21 4 3 3.5 2 1 1.5
22 4 2
23 4 2
24 4 2 0 1
25 4 0
26 4 3 3.5 0
27 6 5 5.5 4 1 0 0.5
28 6 5 5.5 4 2 0 1
29 5 4 4.5 4 2
30 6 5 5.5 4 2 1 1.5
Source: Alaska Department of Fish and Game.
\
..J
.., -,; \
ALLISON CREEK
December 1979 Januarv , 1980 Februarv 1980
" Co
t
"'-HIgh Low Aver. High Low Aver. High Low Aver.
Temp. Temp. Temp. Temp. Temp. Temp Temp. Temp. Temp.
1 1 -0.3 -0.3 -0.6 -0.5
2 1 0 0.5 -0.3 0 .• 1 -0.4 -0.2
3 0.5 0.0' -0.4 -0.2 0.1 0.0 0.1
4 Q 0.1 0.0 0.0 0.0
5 0 0.4 0.1 0.2 0.0 -0.4 -0.2
6 -0.3 -0.3 0.6 0.5 0.5 0.1 0.0 0.1
7 -0.3 0.6 0 .. 5 0.5 0.1
8 -0.3 0.5 0.1
9 -0.3 0.5 0.0 0.4 0.1 -0.1 0.0
10 -0.3 0.0 -0.4 -0.3 0.3 -0.2 0.0
.~ 11 -0.3 -0.4 -0.5 -0.5 0 .• 5 0.3 0.4
.--"",' 12 -0.3 -0.4 -0.3 -0.5 0.4 0.2 0.3
13 -0.3 --J.l -0.6 -0.3 0.2 0.0 0.1
14 -0.3 -0.4 -0.4 0.2 -0.1 0.1 0.1
15 -0.3 -0.5 -0.4 0.2 0.1 0.0 0.0
16 0.2 -0.2 0.1 0.6 0.2 0.3 0.1 -0.1 0.0
17 0.4 0.3 0.4 0.5 0.1 0.2 0.0 -0.7 -0.4
18 0.2 -0.3 -0.1 0.3 0.1 0.2 -0.5
19 0.3 -0.2 0.1 0.4 0.1 0.2 -0.4 -0.7 -0.5
20 0.6 0.4 0.5 0.2 0.0 0.1 -0.2 -0.4 -0.3
21 0.5 0.2 0.3 0.1 -0.3 0.0 0.0 -0.2 -0.1
22 0.2 0.1 0.1 -0.4 -0.5 -0.5 0.3 0.0 0.1
23 0.2 0.1 0.2 -0.5 0.8 0.4 0.6
('0r}) 24 0.6 0.2 O.~ -0.5 -0.7 -0.6 0.9 0.7 0.8
~ -s-;-~.
25 0.8 0.6 0.7 -0.4 -0.6 -0.5 0.7 0.4 0.5
ALLISON CREEK
---" December 1979 Januarv 1980 Februarv 1980 I
\ ,J CO
High Low Aver. High Low Ayer. High Low Aver.
Temp. Temp. Temp. Temp. Temp. Temp Temp. Temp. Temp.
26 0.8 -0.5 1.0 0'.7 0.8
27 0.8 0.7 0.3 -0.2 -0.5 -0.3 1.0
28 0.8 0.2 -0.1 0.1
29 0.8 0.5 0.7 0.1 -0.7 -0.4
30 0.3 0.1 0.2 -0.6
Source: Alaska Department of Fish and Game.
37
Allison Lake Tem~erature Data
:1ay 7, 1979
() TYEe Probe f.!1 Probe 1F2 Probe f!3
. ..,J
Ice Thickness 1 Ft. 3 A 6 Ft.
Overflow 1..5 Ft. 0 0.5 Ft.
Tem~erature. °c
-0.25 0 _0.25 0 Surface (to~ of ice) +0.25 0
1 Xeter -0.25 -0.25 0.00
2 -0.25 0.00 0.00
2.5 +0.25 +0.25
3 0.25 +0.25 0.30
3.5 0.50 +0.75 0.75
4 1.00 1. 25 1. 50
4.5 2.00 1. 90 2.40
5 2.25 2.40 2.50
5.5 2.75 2. 75
6 2.75 3.00 2.90
6.5 3.00 3.00
7 3.00 3.25 3.10
7.5
8 3.25 2.25 3.25
8.5
9 3.25 3.25 3.30
9.5
10 3.25 3.30 3.30.
10.5
J 11 3.25 3.30 3.30
12 Bottom@ 12.25 M 3.30 3.30
13 3.40 3.30
Source: Corps of Engineers.
SOLOMON CREEK
r . "
' ... ...c/ September 1979 October 1979 0fovember 1979
CO
High Low Aver. High Low Aver. High Low Aver.
TemE· Temp. Temtl. Temtl. Temo. Temtl. Temu. Temu. Temp.
1 12 5 6 ~
2 12 6 J
3 9 6 8 3
4 11 6 7 3
5 6 5 7 2
6 12 5 7 1
7 5 8 1
8 5 8 1
9 10 5 8 0
10 12 7 11 5 2 1
11 12 7 5 3 2
12 13 8 5 3 2
13 12 9 5 2 1
14 13 8 5 1.5
15 8 4.5 4.5 1.5
16 8.5 4.5 3.5 6 1.5
I~ 17 7 7 4 6 2
18 7 6 10 4 6 1
19 7 10 4 6 1
20 7 11 4 5 0
21 7 6 10 3 7 1
22 6 9 2 7 1
23 6 9 2 7 1
24 6 9 2 6 1
25' 6 9 3 6 1
26 6 9 3 6 1
27 6 9 3 5 1
28 9 6 8 3 6 1
29 11 6 9 3 5 1
30 6 9 3 6 1
Source: Alaska Department of Fish and Game.
RESPONSES TO RECOMMENDATIONS of the U.S. Fisn and ~ildlife Service in the
"Final Coordination Act Report.
1. That the design of the powerhouse allow the release of regulated
flows to Allison Creek throught the tailrace and excess flows to Port
Valdez through the other tailrace.
Response: The selected plan includes a two tailrace system which would
allow regulated flows to both Allison Creek and Port Valdez.
2. That flows from the powerhouse tailrace to Port Valdez be disCharged
subtidally to at least -10 feet MLLW from June through September.
Response: During the advanced engineering and design phase, studies will
oe conducted to determine stream temperatures with project operation. If
these studies indicate the stream temperature during the spawning would
be below the critical level and all the project diSCharge COuld not be
diSCharged into Allison Creek during spawning, mitigative measures, such
as a subtidal outlet would probaoly be employed.
3. That the proposed start-up of project operation affecting the natural
flows in Allison Creek occur in an even year.
Response: The initial drawdown for securing the tap and the placement of
trash racks WOuld probably occur during the winter months when flows into
the Port Valdez tailace and would have no impacts on the incubating eggs
within Allison Creek and the intertidal area. Project operation would
probably occur with the refilling of the lake the same year as the
drawdown. It would be impossible at this time to insure project startup
would occur in an even year.
4. That the timing of proposed construction activities in or on the
banks of Allison Creek be coordinated with the FWS, .NMFS, and the ADF&G.
Response: This recommendation will be included in the stipulations to
the contractor.
s. That streambanks be restored to preproject integrity during the
construction season in which they are damaged and debris or vegetation be
kept out of streams.
Response: Refer to response to number four.
6. Tnat any structures placed in or across streams be removed during the
same construction season.
Response: Refer to response to number four.
7. That clearing for the penstock construction be limited to large
snrUDS and any trees wnich may be encountered.
8~ That during the const:'uction phase, bulk fuels, lubricants, and other
potential pollutants be stored in leakproof containers within an area
surrounded by a containment berm at a minimum of 300 feet from any stream
or water body.
Response: Refer to response to number four.
9. That no feeding of wildlife occur and all refuse be placed in metal
containers with heavy lids and removed regularly.
Response: Refer to response to numoer four.
10. That the transmission line cOflstrtJcticn be governed by "Suggested
Practices' for Raptor Protection on Powerlines," Raptor Research
Foundat ion, 1975.
Response: The design of the transmission lines will follow the above
practices.
11. That clearing for the transmission line right-of-way be limited to
only that area needed for construction and be reduced by leaving shrubs
and blending the edges of the clearing with the surrounding vegetation.
Response: Refer to response to number four.
12. That an erosion control plan and instream work plan be prepared and
made available to resource agenci€s for review and comment before
construction.
Response: Little instream work is anticipated, however the
recommendation will be included in the stipulations to the contractor.
13. That the CE collect natural discharge data of Allison Creek
continuously for at least one year, beginning as soon as possible.
Response: At least one stream gage will be installed on Allison CreeK
during the advanced engineering and design phase and it will collect data
for several years.
14. That the Cc maintain the thermograph in Allison Creek to collect
natural temperature data continuously curing the one year period that
other temperature data is recoraed.
Resp.onse: The thennograpl1 is in place at this time and will remain
col :ecting temperatures well after project completion.
i5. That the CE collect intragravel temperature data of Allison Creek
continuously for at least one year, beginning as soon as possible.
Response: Intragravel temperature data will be collected during the
advanced engineering and design phase.
16. That the CE take temperature profiles of Allison Lake to the lake
tap depth ana temperature, dissolved oxygen, turbidity, heavy metal, and
pH readings at the lake surface as well as the depth of the lake tap.
These measurements should be collected as soon as possible. A minimum
sampling effort would include the months of March, June, September, ana
December.
Response: Refer to response to number 15.
17. That the CE collect continuous temperature data below the proposed
tailrace into Allison Creek for at least the first year of project
operation.
Response: The thermograph which is now operating in Allison Creek will
continue to collect data for at least the first year after project
completion.
18. That the CE determine the base flow in Allison Creek expected aOove
the powerhouse after project operation.
Response: Preliminary estimates have been completed and are included in
this report. A gage will be installed during AE&D and maintained after
project completion.
19. Response: An eagle nest survey will be conducted prior to any
construction associated with the project.
20. That provisions be included in advanced project planning for
escapement survey of salmon in Allison Creek by the FWS or ADF&G.
Response: ADF&G, has indicated they would increase their effort on
Allison Creek. During AE&D at least one year of intensive an escapement
survey will be conducted.
21. That provisions be made in advanced project planning for instream
flow analysis of Allison Creek by the FWS to determine optimum flow
schedules and the velocity of supplemental flows to Allison Creek.
Response: Provisions for flow analysis of Allison Creek will be included
in the AE&D phase. Whether an extensive instream flew analysis is
reauirea is not known at this time.
1
2
3
4
5
fi
7
8
9
1(1
11
12
13
14
15
16 , 17
~ 18
19
20
21
22
23
24
7C: _oJ
26
27
28
"0 ,-,
30
December 1979
High
Temp.
6
6
7
7
7
" 7
6
5
1
n.':;
3.8
2.4
4.0
3.7
4.5
4.4
4.5
4.n
4.6
3.7
3.3
4.8
4.8
4.4
4.3
3.2
3.0
2.9
Low
Temp.
1
1
1
1
0
(1
0
0
0
-0.7
-0.6
-0.6
-0.6
-n.5
-n.S
-0.5
-0.7
-0.5
-0.3
-0.4
-0.4
-0.3
-0.4
-0.2
-0.2
-0.2
-0.2
-0.2
-0.3
-0.5
Aver.
Temp.
SOLO~ON CREEK
Januarv lQ~O
High
Temp.
3.8
4.1
2.5
3.5
3.7
3.1
3.3
3.2
1.2
7 -_. l
2.9
2.2
2.9
3.4
2.9
3.1
2.8
3..0
2.3
2.6
3.0
2.0
1.R
1.8
2.1
1.5
3.1
2.R
2.4
2.8
L<1w
Temp.
-0.5
-0.3
-0.4
-0.2
-0.2
-n.2
-0.2
-0.2
-0.5
-0.5
-0.6
-0.6
-0.3
-n.S
-n.3
-0.3
-0.2
-0.2
-n.2
-0.2
-n.2
-0.3
-n.5
.-0.5
-0.5
-0.5
-0.4
-0.5
-0.5
-0.5
Aver.
Temp.
Source: Alaska Department of Fish and Game.
Februarv I,?Rn
High
Temp.
2.9
3.0
3.1
2.2
2.5
2,r1
2.2
2,1')
1.':;
1.7
2.0
1,1')
1.7
1.9
1.8
1.7
2.1
2.0
2.8
2.n
2.5
2.n
2.0
2.0
2. 4
2.3
3.8
Low
Tel!lp.
-n.4
-0.3
-n.3
-n.5
-n.1
-n.3
-r..t..
-0.5
-n.5
-n.2
-0.4
-n.R
-n.':;
-n.s·
-n.4
-n.7
-n.5
-n.5
-0.4
-0.3
-n.3
-n.3
-0.4
-11.5
.,.0.3
..,.0.2
-0.2
Aver.
Temp.
(~ ..
22. That a cooperative study of the proposed Allison Creek Hydropower
project, jointly scopea by the C: and FWS and funaed by the CE, be
conductea through project construction and operation.
Response: The U.S.F.W.S. will be involved in the scoping process for
environmental stuaies auring the AE&D.
23. That, if after execution of the recommended additional studies, it
is determined that some losses to fish and wildlife are unavoidable,
those losses be offset by 'implementation of mitigation measures mutually
acceptable to the FWS and the CEo
Response: The CE is in full accord.