HomeMy WebLinkAboutFinal Report Review of Icing Studies Contract No.15800.12-36 1987"RECORD COPY"
RETURN TO BRADLEY O&M FILES
FINAL REPORT
REVIEW OF ICING STUDIES
CONTRACT N0.15800.12-36
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BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
Prepared for
STONE & WEBSTER ENGINEERING CORPORATION
ANCHORAGE, ALASKA
JUNE 1987
NORTEC
A DIVISION OF £liT
NORTEC
A DIVISION OF ERT
750 WEST SECOND AVENUE , SUITE 100, ANCHORAGE , AK 99501 , (907) 276-4302
environmental and engineering excellence
June 29, 1987
Stone & Webster Engineering Corporation
Bradley Lake Project Office
800 A Street
Anchorage, Alaska 99501
Attention: Mr. Norm Bishop
Subject: Final Report
Gentlemen:
Review of Icing Studies
Contract No. 15800.12-36
Enclosed i s our final report for the subject contract. Comments
received for the interim report have been reviewed and
appropriate changes have been incorporated. If you should have
any additional comments or questions, please don't hesitate to
call.
Yours very truly,
NORTEC, A Division of ERT
i:wf~d
Robert P. Britch, P.E.
Manager of Engineering
Enclosure
RPB/mlb
E822
ALASKA • CALIFORNIA • COLORADO • ILLINOIS • MASSACHUSETTS • NEW JERSEY • PENNSYLVANIA • TEXAS • WASHINGTON
FINAL REPORT
REVIEW OF ICING STUDIES
CONTRACT N0.15800.12-36
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
Prepared for
STONE & WEBSTER ENGINEERING CORPORATION
ANCHORAGE, ALASKA
Prepared by
NORTEC, A DIVISION OF EAT
ANCHORAGE, ALASKA
JUNE 1987
TABLE OF
CONTENTS
TABLE OF CONTENTS
Section Section Title Page
1.0 EXECUTIVE SUMMARY 1-1
1.1 BACKOROUND 1-1
1.2 SUMMARY OF FINDINGS 1-2
2.0 SUMMARY OF TECHNICAL DATA 2-1
2. 1 GENERAL SETTING 2-1
2.2 CLIMATE AND METEOROLOGY 2-1
2. 2. 1 General 2-1
2.2.2 Air Temperatures 2-2
2.2.3 Winds 2-2
2.2.4 Precipitation 2-3
2.3 HYDROLOGY 2-4
2. 3. 1 General 2-4
2.3.2 Streamflow Data 2-4
2.3.3 Water Temperatures 2-5
2.4 OCEANOGRAPHY 2-5
2. 4. 1 General 2-5
2.4.2 Bathymetry 2-6
2.4.3 Tides 2-6
2.4.4 Currents and Circulation 2-7
2.4.5 Waves 2-8
2.4.6 Salinity and Temperature Distributions 2-8
3.0 LOCAL INTERVIEWS 3-1
3. 1 INTRODUCTION 3-1
3.2 RESULTS OF INTERVIEWS 3-2
3. 2. 1 General 3-2
3.2.2 Types of Ice 3-2
3.2.2.1 Sea Ice 3-2
3.2.2.2 Beach Ice 3-3
3.2.2.3 Stamukhi 3-3
3.2.2.4 Estuary Ice 3-4
3.2.2.5 Drift Ice 3-4
3.2.3 Factors Affecting Ice Formation 3-5
3.2.4 Ice Occurrence and Distribution 3-6
3.2.4.1 General 3-6
3.2.4.2 Mild Winter Ice Events 3-6
3.2.4.3 Moderate Winter Ice Events 3-7
3.2.4.4 Extreme Ice Events 3-7
4.0 COLLABORATION AND DISCUSSION OF LOCAL
INTERVIEWS 4-1
4. 1 GENERAL 4-1
4.2 ICE TYPES 4-1
4.3 FACTORS AFFECTING ICE FORMATION 4-2
4. 3. 1 General 4-2
4.3.2 Air Temperatures 4-2
4.3.3 Tides and Currents 4-3
4.3.4 Freshwater Inflows 4-4
1-1544-JW i
Section
5.0
6.0
7.0
8.0
5. 1
5.2
5.3
5.4
5.5
5.6
6. 1
6.2
6.2. 1
6.2.2
6.2.3
6.3
6. 3. 1
6.3.2
6.3.3
6.3.3.1
6.3.3.2
6.3.3.3
7. 1
7. 1 . 1
7. 1 • 2
7. 1.3
7. 1. 4
7. 1.5
7.2
7. 2. 1
1.2.2
7.2.3
7.2.4
7.3
8. 1
8.2
8.2. 1
8.2.2
8.2.3
8.3
8. 3. 1
8.3.2
8.3.2.1
1-1544-JW
TABLE OF CONTENTS (continued}
Section Title
REVIEW OF PREVIOUS PROJECT REPORTS 5-1
BACKGROUND 5-1
BURBANK CIRCULATION STUDY 5-1
COLONELL CIRCULATION AND DISPERSION STUDY 5-2
GATTO STUDIES 5-3
GOSINK AND OSTERCAMP STUDIES 5-4
DALY REPORT 5-6
EXISTING HYDROPOWER PROJECT CASE HISTORIES 6-1
BACKGROUND 6-1
INFORMATION SOURCES 6-1
General 6-1
Literature Review 6-1
Individual Contacts 6-2
CASE HISTORIES 6-2
General 6-2
Inland Hydropower Projects 6-3
Coastal Hydropower Projects 6-4
Norwegian Facilities 6-5
Canadian Facilities 6-6
Alaskan Facilities 6-9
REVIEW OF PROPOSED OPERATIONS 7-1
BACKGROUND 7-1
General 7-1
Conceptual Tailrace Configuration 7-1
Preliminary Tailrace Configuration 7-2
Alternate Tailrace Configuration 7-2
Present Tailrace Configuration 7-2
FACTORS PERTINENT TO THE REVIEW 7-3
General 7-3
Discharges 7-3
Oceanographic Conditions and Ice Formation 7-3
Themodynamic Considerations 7-4
POTENTIAL PROJECT MODIFICATIONS 7-6
BASELINE DATA COLLECTION AND ADDITIONAL
STUDIES 8-1
GENERAL 8-1
PHASE I -NEARFIELD ICE FORMATION MODELING 8-2
Purpose 8-2
Methods 8-2
Timing 8-3
PHASE II -BASELINE DATA COLLECTION 8-3
General 8-3
Meteorological Data Collection 8-4
Purpose 8-4
ii
TABLE OF CONTENTS (continued)
Section Section Title
8.3.2.2 Methods
8.3.2.3 Timing
8.3.2.4 Other Considerations
8.3.3 Oceanographic Data Collection
8.3.3.1 Purpose
8.3.3.2 Methods
8.3.3.3 Timing
8.3.4 Ice Sampling
8.3.4.1 Purpose
8.3.4.2 Methods
8.3.4.3 Timing
8.4 PHASE III -FARFIELD ICE TRANSPORT MODELING
8. 4. 1 Purpose
8.4.2 Methods
8.4.3 Timing
8.5 SUMMARY
9.0 BIBLIOGRAPHY
APPENDIX A -NOTES OF LOCAL INTERVIEWS
APPENDIX B -REVIEW COMMENTS
1-1544-JW iii
Page
8-4
8-5
8-5
8-5
8-5
8-6
8-7
8-7
8-7
8-7
8-8
8-8
8-8
8-8
8-9
8-9
9-1
LIST OF TABLES
TABLE
2-1
2-2
2-3
2-~
2-5
2-6
2-7
2-8
2-9
2-10
2-11
3-1
3-2
3-3
6-1
6-2
6-3
1-15~~-JW
LIST OF TABLES
SUBJECT
Mean monthly air temperature at the
Homer WSO
Number of days when the air temperature
fell below 32° F at the Homer WSO
Number of da~s when the air temperature
fell below 0 F at the Homer WSO
Summary of wind data from the Homer WSO
Summary of precipitation data from the
Homer WSO
Mean monthly streamflows for the Bradley
River at the outlet of Bradley Lake
Analysis of daily variations in winter
flows from the Bradley River at the
outlet of Bradley Lake
Summary of predicted pre-project mean
monthly flows
Summary of water temperature data for the
Bradley River at the outlet of Bradley
Lake
Summary of tidal datum for Kachemak Bay
Summary of physical characteristics of
Kachemak Bay
List of local residents contacted or
interviewed
Classification of ice in Kachemak Bay
Summary of extreme ice events in Kachemak
Bay
List of reports and publications obtained
during the literature review
Individuals contacted as part of the review
List of hydropower projects identified as a
result of the literature review and individual
contacts
iv
PAGE
2-11
2-12
2-13
2-1~
2-15
2-16
2-17
2-18
2-19
2-20
2-21
3-8
3-9
3-10
6-10
6-12
6-13
LIST OF FIGURES
FIGURE
2-1
2-2
2-3
3-1
3-2
3-3
4-1
4-2
7-1
7-2
7-3
7-4
7-5
8-1
8-2
8-2
1-1544-JW
LIST OF FIGURES
SUBJECT
Location map of the study area
Mean monthly air temperatures at the Homer
wso
Generalized surface circulation patterns
in Kachemak Bay
Typical extent of ice during a mild winter
Typical extent of ice during a moderate
winter
Reported extent of ice during February 1947
Annual number of days when the air temperature
at the Homer WSO dropped below 32° F
Annual number of days when the air temperature
at the Homer WSO dropped below 0° F
Conceptual tailrace configurations
Preliminary engineering tailrace configurations
Alternate tailrace configuration
Present design tailrace configuration
Configuration of the present tailrace and
discharge canal
Approach to additional studies
Station locations for salinity and temperature
measurements
Locations of ice sampling stations
v
PAGE
2-22
2-23
2-24
3-11
3-12
3-13
4-6
4-7
7-8
7-9
7-10
7-11
7-12
8-10
8-11
8-12
SECTION 1.0
EXECUTIVE SUMMARY
1.0 EXECUTIVE SUMMARY
1 • 1 BACKGROUND
There has been recent concern expressed by residents of the Kachemak
Bay area regarding the thoroughness and conclusions of the Corps of
Engineers' ice studies conducted for the Bradley Lake Hydroelectric
Project. Local residents indicated the following points concerning the
previous ice studies:
1. The studies do not reflect the solicitation of "local knowledge"
from local fisherman and area residents.
2. Given the terminology used in the studies, it is difficult for the
layman to understand and interpret the studies.
3. The reports do not address "anchor" ice as termed by the local
fisherman and area residents.
As a result, Stone & Webster Engineering Corporation (SWEC), the
project design contractor for the Alaska Power Authority, contracted
with Northern Technical Services, Inc. (currently NORTEC, a Division of
ERT) to conduct a number of specific tasks in response to local
resident concerns. These tasks are as follows:
1. Solicit local knowledge from local fisherman and area residents
regarding the types of ice problems, extent, duration and other
observations noted. Special attention is required to identify and
differentiate between the local definitions of the types of ice
observed including "anchor ice". The existing studies'
terminology of the past ice reports may need to be clarified
and/or correlated to local definitions.
2. Review and critique the previous studies including the adequacies,
background data, other known data, assumptions, considerations,
analyses, and conclusions of the studies.
2-1544-RW 1-1
3. Research and identify any existing hydroprojects of comparable
climatic and geographic conditions which may provide useful case
history to aid in the predictions of ice formation due to the
Bradley Lake Project tailrace.
4. Review the proposed project operating plan for the winter months
and the tailrace design and provide comments regarding ice
formations which may result from powerhouse discharge.
5. Prepare a suggested scope of work for the collection of baseline
and post-project ice data and suggested plan for post-project
analysis.
6. Identify additional ice studies or further reviews, if any, which
would be beneficial in substantiating the probable icing effects
of project operations.
7. Participate in committee meetings of local Kachemak Bay residents
who will be involved in the review of this work effort.
8. Prepare a report summarizing the efforts on the above tasks.
The following section briefly summarizes the findings and results of
these tasks.
1.2 SUMMARY OF FINDINGS
Local residents provided personal observations and historical
information on ice formation and distribution in Kachemak Bay. This
information is presented in Section 3.0 and discussed in Section 4.0.
Key findings and conclusions from this effort are summarized as
follows:
1. Ice formation is a relatively common occurrence in the inner
Kachemak Bay at various times during the months of November
2-1544-RW 1-2
through April; however, ice conditions for the past 10 years have
been relatively mild.
2. Ice typically forms every year along the beaches at the head of
and along the northern shore of the inner bay. Northeasterly
winds, which prevail in the winter, tend to accumulate it against
the Homer Spit where it can impede boat operations.
3. Tides and currents also play important roles in both ice formation
and in redistribution of ice within the inner bay ..
4. Ice cover can be quite extensive during periods with consecutive
days of cold, clear and calm weather. As an extreme case, ice
covered the entire inner bay during February, 1947 (see Section
3.0, Figure 3-3).
5. There are a number of types of ice which occur in the inner bay.
Predominant forms include beach ice and drift ice. Stamukhi
(chunk or cake ice), sea ice and estuary ice also occur, but are
generally less abundant except during extreme cold weather.
A review of the previous project reports is presented in Section 5.0.
In general, most data reports, including those by Burbank (1977) and
Gatto (1981), provide useful background information on circulation
and/or ice conditions within Kachemak Bay. Studies by Colonell (1980)
on circulation and dispersion hypothesized that the mixing of Bradley
River fresh water with the bay's marine waters is fairly rapid, with
nearly complete mixing occurring within 3 to 4 tidal cycles. Gosink
and Ostercamp (1981) modeled the potential for ice effects from
additional winter dischargers. Based on a review of information
available since the Gosink and Ostercamp study, we would conclude that
additional factors should be considered when modeling the potential for
ice formation in the bay.
A literature review and individual contacts were conducted to identify
any existing hydropower projects of comparable climatic and geographic
2-1544-RW 1-3
conditions similar to the Bradley Lake Project. The results of this
effort are discussed in Section 6.0. Based on this review, 16
hydropower projects were identified which discharge flows to tidal
estuaries. Three were located in Norway, 11 in Canada and two in
Alaska. While the details of climatic and oceanographic conditions are
not sufficiently known to determine whether they are directly
comparable to the Bradley Lake Project, the type of problem which may
occur has been determined and is pertinent to this review. Of the
three Norwegian projects, two had, been constructed and sheet ice
formation resulted in previously ice free fjords. Of the 11 Canadian
facilities, six reported ice problems; four reported beach ice and two
reported estuary ice. Both Alaskan projects reported natural ice
conditions may have been slightly reduced by additional tailrace
discharges. Based on a comparison of the Bradley Lake Project site
conditions with other hydropower projects, it is believed that there is
some potential for formation of beach ice and perhaps, to a lesser
degree, the potential for formation of estuary ice as a result of the
Bradley Lake Project.
Based on a review of the Bradley Lake Project designs, modifications
made to tailrace design to date are believed to have lessened the
potential for ice formation. Although specific effects have not been
quantified as part of this study, preliminary thermodynamic
calculations suggest ice formation could occur slightly earlier (e.g.
at less severe winter temperatures) and could persist for a slightly
longer duration. Effects, if they occurred, would depend on the degree
of mixing of the tailrace discharge with bay waters and would likely be
defined in terms of either hours or days. While measurable effects may
occur locally at the head of the bay, it will be difficult to quantify
effects at Homer, some 20 miles from the tailrace.
In order to quantify potential effects of winter discharges, a three
phased study approach is recommended. Phase I would be conducted in
1987 and include an assessment and modeling ice formation processes at
the head of the inner bay where problems, if they occur, would be most
evident. This nearfield assessment would include a numerical modeling
effort to examine both beach and estuary ice formation.
2-1544-RW 1-4
Phase II efforts would include baseline data collection programs
conducted during the 1987-88 winter. Three individual studies are
envisioned:
1. Collection of meteorological data at the tailrace site to verify
temperature differences between the site and Homer.
2. Collection of additional oceanographic data to
stratification and mixing at the head of the inner bay.
define
3. Documenting and sampling the various types of ice to confirm
mechanisms for ice formation.
Phase II I would include a far field ice transport modeling effort to
predict effects over the entire inner bay, including Homer. This
numerical model should include both an ice formation model and an ice
transport model.
In this recommended phased approach, the need for additional studies
would be reevaluated at the end of each phase. Post-project
monitoring, if required, would be similar to those as outlined for
Phase II.
Requir-ements for mitigation measures should be reassessed at the
completion of each of the study phases. Options for mitigating ice
problems, should they be needed, appear to be fairly straight forward.
An obvious non-structural solution would include reducing the tailrace
discharge during extreme cold weather when ice formation is most likely
to occur. The only structural modification which appears to provide
some benefits includes containing the tailrace discharge to insure that
it is discharged to deeper water to insure a more rapid mixing with the
marine waters. These options are discussed in Section 7.0.
2-1544-RW 1-5
SECTION 2.0
SUMMARY OF
TECHNICAL DATA
2.0 SUMMARY OF TECHNICAL DATA
2.1 GENERAL SETTING
Kachemak Bay is a 35 mile long embayment located on the eastern side of
lower Cook Inlet. The bay is naturally divided into the inner and
outer bays by the 4 mile long Homer Spit (see Figure 2-1). The north
shore of Kachemak Bay is bordered by mud flats with scattered rocks and
boulders; these are backed by coastal bluffs and rolling hills. The
south shore of the bay is fairly irregular with numerous deeper
embayments, islands and a predominance of gravel or rocky beaches
backed by the Kenai Mountains. The head of Kachemak Bay has extensive
tidal flats and are backed by a 3 to 4 mile wide glaciated valley.
2.2 CLIMATE AND METEOROLOGY
2 . 2. 1 General
The climate at Kachemak Bay is classified as marine but with precipita-
tion amounts modified by the Kenai Mountains. The annual precipitation
is reduced when air being lifted over the mountains leaves most of its
moisture on the windward (southern) side. For this reason, the normal
Gulf Coast precipitation of near 60 inches is reduced to less than half
of that amount at Homer. The relatively low annual snowfall is a
reflection of the mild winter temperatures. Often precipitation will
begin as snow but turn to rain shortly afterwards. The occurrence of
the heaviest monthly precipitation during the fall and winter months is
the result of the increased frequency of storms in the Gulf of Alaska
during those months.
Temperatures experienced in the area are more representative of a
marine climate than is precipitation. Winters are mild and tempera-
tures seldom get below 0°F; summers are cool with the maximum tempera-
tures seldom going above 70°F. The range between the average maximum
and minimum temperatures does not exceed 16°F during any of the 12
months.
2-1544-RW 2-1
Surface winds at Horner are seldom strong, even in winter. However,
over outer Kachemak Bay and to the west over Cook Inlet, wind speeds
requiring warnings to small craft are fairly common in winter and
summer.
The occurrence of thunderstorms are rare. Heavy fog is infrequent and
of short duration, but patchy ground fog is common in spring and fall.
Meteorological data have been collected at the Homer Weather Service
Office (WSO) since 1932 and are the primary source of data discussed in
this section. Additional shorter periods of record are also available
for the project site and other locations around the bay. These data
are also discussed or summarized in the following sections.
2.2.2 Air Temperatures
Air temperature data for the Homer WSO are summarized on Table 2-1 and
Figure 2-2. Data gaps occur in this record during the years 1932,
1934-1939, 1966 and 1973. Mean monthly temperatures for the period of
record range from about 22°F in January to 53°F in July and August.
Extreme mean monthly temperatures ranged from 9°F (January, 194 7) to
58°F (July, 1936). Daily extremes at the Homer WSO for the period of
record ranged from -21° (April, 1971) to 80°F (June, 1953).
Ice formation is dependent to a large extent on the occurrence and
persistence of colder air temperatures. Table 2-2 and 2-3 present the
number of days per month when air temperatures fell below 32°F and 0°F,
respectively. On the average, there are 188 days annually with air
temperatures less than 32°F and 13 days annually with temperatures less
than o°F. Extremes of record included 219 days less than 32°F (1956-57
winter) and 35 days less than 0°F {1946-47 winter). The average and
extreme number of days did not necessarily occur consecutively.
2.2.3 Winds
Wind data are available from the Homer WSO for the years 1963 to 1985.
These data are summarized on Table 2-4.
2-1544-RW 2-2
Mean monthly wind speeds at the Homer WSO vary from 5.9 mph in August
to 8.0 mph in January and February with a mean annual wind speed of 7.3
mph. Prevailing directions are from the southwest and west-southwest
during May through August and from the northeast for the remainder of
the year. The extreme wind of record for the station was reported at
44 mph in November, 1983. Other extreme events include winds typically
from the east or west and are presumably channelled to some extent by
the local topographic features {namely the east-west orientation of the
Kenai Mountains).
ARCTEC { 1985) conducted an extreme wind analysis and compared the
longer term wind record for Homer with shorter data sets from both the
Homer Spit (1965-1973) and from Sheep Point at the head of the Bay
{November 1980 to September 1981). Based on their analysis, they
determined that for winds greater than 10 mph, the wind at the Homer
Spit was 1.4 times that at the Homer WSO and winds at Sheep Point were
2.1 times that at the Homer WSO.
The ARCTEC report also provided a discussion of wind conditions in the
vicinity of Sheep Point. They concluded that the geography in the area
dominates the wind regime. Due to the restricted nature of the bay
near Sheep Point, there is little opportunity for winds to blow from
any direction but along the major axis of the bay. An exception is
downslope winds from the mountains immediately behind Sheep Point (most
frequently down Battle Creek). ARCTEC further indicate that this
effect is probably diurnal in nature {e.g., it occurs only at certain
times of the day).
2.2.4 Precipitation
Precipitation data, both as total water equivalent and as snowfall, are
reported for the Homer WSO for the period of 1943 to 1985. Statistical
summaries of these data are provided on Table 2-5.
Precipitation is normally lowest in the summer and greatest in the fall
and early winter months. Mean monthly vary from 1.05 inches in June to
3.28 inches in October. Extremes of record ranged from 0.00 inches
2-1544-RW 2-3
(December, 1933) to 8.72 inches (November, 1983). The greatest 24-hour
precipitation on record of 3.20 inches occurred in November, 1983 (NCC,
1986).
Snowfall may occur during the months of September through June,
although the greatest snowfall normally occurs during December through
March. December has both the greatest mean monthly snowfall ( 12.9
inches) and the highest snowfall of record (54.7 inches in 1979). The
maximum recorded snowfall in 24 hours was 24.5 inches in November, 1945
( NCC, 1986) .
2.3 HYDROLOGY
2.3. 1 General
Runoff characteristics of the larger streams draining into Kachemak Bay
from the southern Kenai Mountains reflect the influence of the Gulf of
Alaska maritime climate and the effects of glaciers which occupy higher
elevations of these basins. Bradley River, which is typical of these
basins, discharge approximately 90 percent of their total flow during
the period of May through October ( COE, 1982). The highest flows
typically occur in the late summer when glacier meltings is great and
precipitation is high.
2.3.2 Streamflow Data
Freshwater inflows into upper Kachemak Bay is primarily from the Fox
River, Sheep Creek, Bradley River, Battle Creek and Martin River. The
U.S. Geological Survey (USGS) has maintained a gaging station at the
outlet of the Bradley River since October, 1957. In October 1979, the
USGS also began obtaining data for the Middle Fork of the Bradley River
and from the Bradley River below Nuka Glacier. Spot measurements have
also been made at the mouths of Fox River, Sheep Creek, Battle Creek,
Martin River and on the lower Bradley River.
Table 2-6 provides a listing of mean monthly flows for Bradley River at
the lake outlet. These data suggest a large variation in winter flows,
which are of primary interest for this report. As an example, during
2-1544-RW 2-4
March, which has the lowest mean monthly discharge, flows varied by a
factor of over 9 (minimum of 19 cfs, maximum of 178 cfs). Table 2-7,
which was provided by SWEC, gives a statistical summary of flows based
on daily discharge values for the months of December through April. As
indicated by the standard deviations, daily variations generally
decrease as the winter progresses, reaching a minimum variation in
March.
Ott Water ( 1981) used regression techniques to provide mean monthly
flows for the other major drainages entering the head of Kachemak Bay.
These are summarized on Table 2-8. Mean monthly flows vary from a low
of 302 cfs in March to a high flow of 5,681 cfs in July. During the
winter months of November through April, the average discharge into the
head of the bay is 610 cfs.
2.3.3 Water Temperatures
The USGS has monitored water temperatures for the Bradley River at the
lake outlet intermittently since October, 1979. Mean monthly values
are summarized on Table 2-9. Water temperatures ranged from a minimum
of 0.0°C (32°F) in winter (November through April) to 12.0°C (54°F) in
late summer (August).
Woodward Clyde et al. (1985) provided some limited data for the period
December, 1984 to April, 1985 for areas at lower elevations on the
Bradley River (Tree Bar Reach). On the average minimum monthly values
reported by Woodward Clyde were 0.1°C (0.2°F) lower (standard deviation
of .:!:_0.2°C) than the USGS data, and maximum monthly values were 0.8°C
( 1.4°F) higher (standard deviation of .:!:_0.8°C). Additional data are
also available during 1986 (Stone & Webster, 1987). These data are in
a raw form and have not been statistically summarized.
2.4 OCEANOGRAPHY
2.4.1 General
Kachemak Bay is a tidal estuary and currents and circulation are
primarily driven by the rise and fall of the tides. Bathymetric
features also have a significant effect on currents and the movement of
2-1544-RW 2-5
water masses within the bay. Inflows of freshwater, particularily at
the head of the bay, have a local effect on the circulation patterns
and water stratification.
2.4.2 Bathymetry
The bathymetry of Kachemak Bay varies within the inner and outer bay.
In the inner bay, water depths are fairly shallow with maximum depths
typically 150 to 250 feet near the center and along the southern
margins of the inner bay. Water depths along the northern third to
half of the inner bay are fairly shallow and seldom exceed 60 feet.
The outer bay is slightly deeper with water depths of 200 to 300 feet
common throughout most of that area. Some deep water (up to 550 foot
depths) occurs south of the Homer Spit near the line separating the
inner and outer bays.
2.4.3 Tides
Kachemak Bay tides are classified as mixed, and as such are
characterized by two unequal high and low waters occurring over the
period of approximately one day. NOAA provides daily predictions for
tidal fluctuations for Seldovia as well as provides corrections for
predicting tides at Homer.
NOAA (formerly the U.S Coast and Geodetic Survey) also provides tidal
bench mark reports which summarize tidal datum for various locations
within Kachemak Bay including Seldovia, Homer, Halibut Cove, and Bear
Cove. These data are summarized on Table 2-10. Based on these data,
the mean tidal range varies from 15.4 feet at Seldovia (near the mouth)
to 16.0 feet at Bear Cove (near the head of the Bay). Diurnal tides
range from a mean of 17.8 feet at Seldovia to 18.5 feet at Bear Cove.
Extreme high and low tides for the bay are estimated at 25.0 feet, MLLW
and -6.0 feet, MLLW.
Knull (1975) provides a discussion of various physical characteristics
of the bay related to the tides; these are summarized on Table 2-11.
Of particular relevance to this study is the intertidal area indicated
on Table 2-11. The inner bay has an intertidal area of approximately
2-1544-RW 2-6
33 mi 2 and the outer bay has about 6 mi 2 of intertidal area. Based on
a review of topographic maps, approximately 35 percent of the inter-
tidal area within the inner bay is located at the head of the bay where
the major streams for the area presently discharge their flow.
Approximately 40 percent of the intertidal area for the inner bay is
located on the north shore and the remaining 25 percent is located
along the south shore.
2.4.4 Currents and Circulation
Currents and circulation in Kachemak Bay are driven primarily by the
tides. Other factors which also are important include the net circu-
lation patterns in Lower Cook Inlet, winds, and effects of freshwater
discharges.
The National Ocean Survey measured currents during May of 1974 at a
location midway between the tip of the Homer Spit and the south shore.
Although currents were typically weak (less than 0.5 knots) and
extremely variable, flood directions were generally towards the north
or northeast and ebb currents typically towards the west or southwest.
Circulation patterns in Kachemak Bay have been documented by several
previous investigations, notably those by Burbank (1977) and Gatto
(1981). Burbank (1977) conducted drogue studies to define currents and
circulation patterns within the bay; these data are summarized on
Figure 2-3. Generalized circulation patterns are based on actual
drogue measurements obtained during a number of individual efforts in
May, June, July, August, September and November of 1975 and in March,
April and May of 1976. While it is likely that there may be some bias
in these patterns towards the spring and summer conditions, the general
patterns indicated on Figure 2-3 are expected to be present to some
extent for the entire year.
Burbank indicated that dominant features within the outer bay are two
gyres (one clockwise and the other counter-clockwise). Flow of rela-
tively clean oceanic waters is generally into the bay along the south-
side of the outer bay and out of the bay along the north shore.
2-1544-RW 2-7
Circulation patterns within the inner bay are generally counter clock-
wise with inflows along the deeper southern side of the bay and
outflows along the northern side. Freshwater from the head of the
inner bay generally flows southwesterly along the northern shore.
Gatto (1981) used suspended sediment patterns as observed on satellite
imagery to infer generalized winter circulation patterns in the
Kachemak Bay. While the gyres in the outer bay were not observed
(probably because sediment concentrations were too low in the winter to
act as a reliable tracer), the circulation patterns as summarized by
Burbank (1977) were generally confirmed.
2.4.5 Waves
Wave data for Kachemak Bay are somewhat limited. The Corps of
Engineers (1984) measured deepwater waves at several locations in the
outer bay in July, 1984. Significant wave heights (average of the
highest 1/3 waves) were typically foot or less. The largest
significant wave height measured was about 2 feet.
ARCTEC (1985) conducted an analysis for extreme deepwater waves at the
center of the inner bay. They estimated significant wave heights of
7. 0 feet for a 1-year return period, 9. 0 feet for a 25-year return
period, and 10.0 feet for a 100-year return period.
2.4.6 Salinity and Temperature Distributions
Information on salinity and temperature distributions within Kachemak
Bay have been reported by Knull (1975), Colonel! (1980), and Ott Water
( 1981).
Knull (1975) reports of three surveys conducted in water depths gener-
ally greater than 60 feet during April, July and October of 1969.
During the April survey, the bay was well mixed top to bottom with no
noticeable gradients except with temperature. The temperature varied
from 2.8°C (37°F) to 3.8°C (39°F) with the cooler water located at the
surface. Salinities varied from 31.6 to 32.1 ppt (parts per thousand)
during this survey. During the July survey, Knull (1977) reported a
2-1544-RW 2-8
strong thermocline was present at depths of 15 to 30 feet in the inner
bay and descending to 30 to 60 feet in the outer bay. Temperatures
ranged from 6°C (43°F) at the bottom to 12°C (54°F) at the surface, and
salinities from 28 ppt at the surface of the inner bay to 31.7 ppt at
depth in the outer bay. By October the water had cooled to 8°C (46°F)
at the surface and 9°C (48°F) at the bottom. Mixing had again
destroyed any noticeable gradients in salinity.
Colonell (1980) reports salinity and temperature data for the head of
the bay in for two periods in October, 1980. Some stratification was
noted about 0.5 mile southwest of the mouth of the Bradley River. At
this point, salinities varied from 0 ppt at the surface to 16.5 ppt at
depth with the strongest gradient noted at depths of 2 to 4 feet; large
gradients in temperatures were not noted. Observations of salinity and
temperature to a depth of 10 to 12 feet in the vicinity of Chugachik
and Bear Islands indicated surface temperatures of 7.5 to 8.5°C (46° to
47°F) and bottom temperatures of 9.0°C (48°F); corresponding salinities
ranged from 19 ppt at the surface to 29.5 ppt at depth.
Ott Water (1981) report various measurements obtained from the mouth of
Bradley River to Bear Island obtained during August, 1979 and March and
August of 1980. Although observations in August, 1979 were generally
limited to within 15 feet of the surface, they do indicate a horizontal
surface gradient extending from the mouth of Bradley River. Within 1
mile of the mouth, salinities of 0.3 to 0.5 ppt and temperatures of 1.2
to 10.3°C (45° to 51°F) were observed. In the vicinity of Chugachik
Island surface salinities ranged from 2.5 to 23.4 ppt and temperatures
from 9.8 to 13.8°C (50° to 57°F); variations in this area were likely
attributed to the effects of tidal flows. Some stratification was
noted in the upper 5 feet of the water column during the August, 1979
survey.
Observations in March, 1980 suggested that the water column was fairly
well mixed, at least in the upper 10 to 15 feet. Horizontal gradients
were however observed with temperatures of 0.3°C (32.5°F) and
salinities of 1.6 to 20 ppt measured at the river mouth. These levels
2-1544-RW 2-9
increased to values on the order of 30 to 34 ppt and temperatures of
1.5 to 3.0°C (35° to 37°F) measured in the vicinity of Chugachik
Island.
Observations in August, 1980 were generally limited to 10 feet or less;
however, some observations were obtained to a maximum depth of 21 feet.
Although some vertical stratification was observed in the upper 3 feet,
the water masses appeared to be fairly well mixed vertically.
Horizontal gradients were, however, again observed during the August
1980 surveys. At the river mouth, temperatures of 7 to 10°C (45° to
50°F) and salinities generally less than 1 ppt were observed. These
values increased to temperatures generally in the range of 10 to 15°C
(50° to 59°F) and salinities up to 30 ppt in the vicinity of Chugachik
Island.
2-1544-RW 2-10
Table 2-1. Mean monthly air temperature (°F) at the Homer WSO (AEIDC, 1986).
YEAR JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN 1932/33 47.2 41.8 23.0 27.6 14.6 25.6 28.0 36.5 42.8 48.4 1933/34 54.2 51.4 45.8 34. 1 32.2 15.0 14.8 34.7 30.4 37.6 42.8 48.2 1934/35 52.9
1935/36 31.4 24.2 30.2 25.4 27.4 37.5 43.8 56. 1 1936/37 58.0 57.0 48.1 44.8 34.8 21.5 31.6 20.2 29.9 36.8 43.0 50.6 1937/38 53.3
1938/39 31.4 26.0 34.6 41.0 48.7 1939/40 52.2 51.2 45.2 34.8 27.8 27.6 31.1 33.0 29.5 41.6 44.4 49.3 1940/41 53.8 53.8 48.4 39.2 31.4 30.8 23.9 33.2 35.4 40.2 43.1 50.6 1941/42 53.0 54.4 47.3 38.9 25.9 27.6 33.3 36.4 29.7 38.6 47.7 50.9 1942/43 53.9 54.7 52.4 41.5 26.4 11.2 16. 1 26.2 29.8 36.4 42.2 49.4 1943/44 52.4 51.4 45.6 40.1 33.4 29.9 25.3 34.4 28.4 34.8 44.4 50.9 1944/45 54.2 55.5 47.4 39.6 30.8 27.9 33.2 29.9 27.6 33. 1 41.6 49.8 1945/46 53.5 53.0 46.4 37.6 20.8 22.9 24.7 24.2 21.1 33.6 42.0 47.4 1946/47 51.7 50.8 46.0 39.8 26.2 12.9 9.4 26.4 31.1 36.2 42.3 47.4 1947/48 51.7 50.8 45.8 37.4 32.8 28.2 25. 1 21.0 25.2 31.9 42.2 48. 1 1948/49 50.4 49.4 44.0 38.2 21.5 17.7 20. 1 16.0 32.0 32.0 39.2 46.9 1949/50 50.4 51.4 47.6 37.5 32.5 17.9 20.1 16.0 32.8 34.9 40.2 47.2 1950/51 50.6 52.8 47.2 36.2 20.7 20.4 16.4 23. 1 18.5 36.4 41.7 48.2
1951/52 52.2 52.8 47.5 35.3 30.1 21.3 14.4 26.5 27.0 33.2 38.6 45.3
1952/53 52.0 52.5 46.8 39.9 35.2 25.6 19.0 26.4 26.5 37.1 42. 1 52.2
1953/54 53.9 53.3 47.2 35.8 29.2 27.5 18.3 14. 1 26.5 32.7 43.6 49.2
1954/55 52.8 52.4 48.5 41.1 32.9 14.6 27.8 23.5 29.6 32.0 41.5 46.5
1955/56 51.5 51.6 46.2 35.0 22.3 15.0 14. 1 17.4 22.8 34.1 41.4 46.7
1956/57 51.5 51.5 44.9 32.3 23.6 14.7 24.0 20.5 32.5 36.7 43. 1 50.6
1957/58 52.9 53.6 48.6 41.4 37.5 18.7 26.7 29. 1 33.2 38.4 44.4 50.5
1958/59 53.6 52.7 45.4 34.0 26.7 24.9 19.6 29. 1 17.7 33.8 42.9 49.5
1959/60 52.0 52.4 46.5 37.7 31.9 23.5 25.3 30.5 26.3 33.7 45.1 47.9 1960/61 53.2 50.8 45.9 38.0 27.5 32.6 27.5 23.0 20.3 35.3 42.9 49.5 1961/62 52.7 52.1 47.6 33.6 25.0 14.3 22.0 26.8 24.9 36.3 41.2 48.7
1962/63 53.0 52.9 43. 1 38.8 29.5 23.8 27.3 27.1 28.7 33.2 43.2 47. 1
1963/64 53.8 53.7 49.7 38.5 20.0 32.3 24.3 25.6 24.0 34. 1 39.0 50. 1
1964/65 51.8 52.7 48.7 38. 1 28.6 12.2 19.4 18.9 35.7 36.0 40.4 45.9
1965/66 51.1 51.1 50.4 33.0 27.0 18.6 22.6 23.1 19. 1 35.6 39.6 49.4
1966/67 52.5 52.2 48.5 34.7 27.4 20.6 18.2 23.4 36.7 44.3 50.2
1967!68 55.2 48.3 37.5 22.7 18.7 27.4 30.4 34.2 43.8 49.6
1968/69 53.4 54.3 45.3 35.3 31.3 15.2 13.2 22.3 31.4 38.3 43.8 50.9
1969170 53.3 50.7 47. 1 42. 1 27.3 33.4 16.3 33.3 35.3 35.0 43.6 48.9
1970171 51.3 51.3. 45. 1 34.3 32.9 19.7 9.7 24.4 18.2 32.9 38.4 46.6
1971172 51.6 53.2 45.9 36.8 25.9 23.0 15.2 19., 16.0 27.1 40.0 46.6
1972173 52.1 53.4 46.5 37.7 30.0 21.7 11.8 21.8 29.6 41.5 48.2
1973174 52.4 51.3 45.8 35.9 22.9 24.6 14. 1 19.5 26.0 36.5 42.7 49.4
1974175 52.9 53.9 49.7 38.4 29.7 24. 1 18.6 18.7 26.0 32.7 42. 1 47.9
1975176 52.9 52.3 47.9 36.9 22.2 19. 1 22.2 20.9 26.6 35.0 41.7 48.0
1976177 53.8 52.7 46.7 36.6 35.5 31.4 37. 1 35.6 27.0 35.1 41.8 51.2
1977178 54.3 55.9 48.5 38.6 21.1 17.2 29.4 30.6 31.9 38. 1 44.3 49.0
1978179 53.0 54.8 47.4 40.2 32.0 29.7 30.7 15.6 32.9 38.4 43.8 48.7
1979/80 55.0 54.6 50.7 42.5 36.0 18.6 18.8 31.5 32. 1 39.2 44.2 50.0
1980/81 53. 1 51.3 48.0 39.8 32.0 12.5 35.5 28.9 36.2 37.3 46.9 49.3
1981/82 54.5 53.7 47.5 39.4 30.2 25.2 21.2 21.0 30.6 33.4 41.9 49.0
1982/83 52.7 52.6 48.2 32.8 32.4 32.3 23.3 30.3 36.2 38.4 46.1 51.8
1983/84 54.6 54. 1 46.8 38.8 34.6 29.2 26.5 22.6 38.0 36.5 43.9 52.3
1984/85 54.6 54.9 49. 1 39.6 30.3 30.7
AVG 52.9 52.8 47.2 37.8 28.8 22.8 22.1 25.2 28.2 35.5 42.6 49. 1
MIN 50.4 49.4 43. 1 32.3 20.0 11.2 9.4 14. 1 16.0 27.1 38.4 45.3
MAX 58.0 57.0 52.4 44.8 37.5 33.4 37. 1 36.4 38.0 41.6 47.7 56. 1
2-11
Table 2-2. Number of days when the air temperature fell below 32°F at the Homer WSO (AEIDC,
1986).
J
YEAR JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN YEARLY
1932/33 0 0 2 10 30 22 31 25 29 19 1 3 178
1933/34 0 0 5 25 23 31 31 19 26 19 3 0 182
1934/35 0 0
1935/36 0 0 23 26 22 29 31 24 2 0
1936/37 0 0 5 3 22 31 26 28 29 28 8 0 180
1937/38 0 0
1938/39 0 0 25 25 28 25 14 1
1939/40 0 0 8 25 29 28 26 27 28 10 12 2 195 1940/41 0 0 3 18 24 23 31 23 24 12 10 0 168 1941/42 0 0 2 17 29 23 18 15 31 13 2 0 150 1942/43 0 0 0 8 27 31 30 20 28 24 12 0 180
1943/44 0 0 5 13 23 26 31 25 26 22 4 0 175 1944/45 0 0 5 16 28 27 24 22 30 26 12 2 192 1945/46 0 0 5 17 29 29 29 27 29 25 9 2 201
1946/47 0 0 11 16 30 31 31 18 27 19 11 3 197 1947/48 0 0 2 19 24 28 27 28 30 29 11 0 198 1948/49 0 0 9 17 28 31 30 28 29 28 16 2 218
1949/50 0 0 3 21 23 31 31 28 . 29 26 18 1 211
1950/51 0 0 2 23 30 30 30 28 30 17 14 2 206
1951/52 0 0 4 21 26 29 31 28 30 24 17 4 214
1952/53 0 0 3 12 19 27 29 25 31 18 15 0 197
1953/54 0 0 3 18 28 28 31 28 31 26 5 0 198
1954/55 0 0 3 12 25 31 28 27 27 30 12 1 196
1955/56 0 1 6 24 30 31 31 28 28 28 9 1 217
1956/57 0 0 9 27 27 30 30 28 28 25 15 0 219
1957/58 0 0 4 18 15 29 30 25 25 26 7 0 179
1958/59 0 0 5 24 27 31 29 27 31 26 9 0 209
1959/60 0 0 6 22 24 31 27 26 31 25 7 1 200
1960/61 0 1 5 24 27 23 26 28 30 22 15 1 202
1961/62 0 0 4 25 28 29 30 26 29 25 14 2 212
1962/63 0 0 0 16 . 25 27 26 26 27 24 10 0 181
1963/64 0 0 1 18 30 23 28 22 31 22 19 0 194
1964/65 0 0 0 18 25 31 27 28 17 25 15 0 186
1965/66 0 0 1 22 29 30 28 28 31 22 18 0 209
1966/67 0 0 2 17 26 31 30 28 27 26 11 0 198
1967/68 0 0 1 20 16 27 29 22 25 24 6 0 170
1968/69 0 0 10 21 22 31 31 25 27 16 10 0 193
1969170 0 0 3 9 25 20 30 20 19 17 9 0 152
1970171 0 0 9 21 21 28 29 24 31 26 15 1 205
. 1971172 0 0 4 20 30 30 30 29 31 30 14 0 218
1972173 0 0 5 21 30 30 30 26 11 1
1973174 0 0 7 21 30 29 31 26 28 23 15 0 210
1974175 0 0 3 14 24 31 24 27 30 23 7 1 184
1975176 0 0 0 18 26 28 30 25 29 27 11 0 194
1976177 0 0 3 19 18 27 17 15 31 21 11 0 162
1977178 0 0 3 14 30 31 25 16 27 19 1 1 167
1978179 0 0 6 10 23 22 27 27 26 17 3 0 161
1979/80 0 0 0 9 19 31 30 25 19 11 1 0 145
1980/81 0 0 3 12 27 30 17 20 22 26 1 0 158
1981/82 0 0 3 12 20 27 29 22 26 26 5 0 170
1982/83 0 0 2 25 21 17 27 21 18 12 0 0 143
1983/84 0 0 3 15 20 26 26 29 18 21 2 0 160
1984/85 0 0 0 13 26 23
AVG 0.0 0.0 3.8 17.6 25.2 27.9 28.0 24.8 27.4 22.4 9.7 0.6 188
MIN 0.0 0.0 0.0 3.0 15.0 17.0 17.0 15.0 17.0 10.0 0.0 0.0 143
MAX 0.0 1.0 11.0 27.0 30.0 31.0 31.0 29.0 31.0 30.0 19.0 4.0 219
2-12
Table 2-3. Number of days when the air temperature fell below 0°F at the Homer WSO (AEIDC,
1986).
YEAR JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN YEARLY
1932/33 0 0 1 0 9 3 0 0 0 0 13
1933/34 0 0 0 0 0 5 15 0 0 0 0 0 20
1934/35 0
1935/36 3 0 2 0 0 0 0
1936/37 0 0 0 0 0 1 0 2 0 0 0 0 3
1937/38 0
1938/39 0 0 0 1 1 0 0 0
1939/40 0 0 0 0 0 0 0 0 0 0 0 0 0
1940/41 0 0 0 0 0 1 0 0 0 0 0 1
1941/42 0 0 0 0 0 0 0 0 0 0 0 0 0
1942/43 0 0 0 0 1 13 10 1 0 0 0 0 31
1943/44 0 0 0 0 0 0 4 0 2 2 0 0 8
1944/45 0 0 0 0 0 0 0 22 0 0 0 0 22
1945/46 ' 0 0 0 0 2 2 0 0 1 0 0 0 5
1946/47 0 0 0 0 0 13 17 5 0 0 0 0 35
1947/48 0 0 0 0 0 0 0 1 0 0 0 0 1
1948/49 0 0 0 0 4 4 6 9 0 0 0 0 23
1949/50 0 0 0 0 0 9 3 9
1950/51 0 0 0 0 0 4 12 2 9 0 0 0 27
1951/52 0 0 0 0 0 3 10 0 0 0 0 0 13
1952/53 0 0 0 0 0 0 1 3 0 0 0 0 10
1953/54 0 0 0 0 0 0 4 13 0 0 0 0 17
1954/55 0 0 0 0 0 8 0 2 0 0 0 0 10
1955/56 0 0 0 0 0 6 9 8 9 0 0 0 32
1956/57 0 0 0 0 1 9 0 3 0 0 0 0 13
1957/58 0 0 0 0 0 6 0 0 0 0 0 0 6
1958/59 0 0 0 0 0 1 4 0 8 0 0 0 13
1959/60 0 0 0 0 0 1 4 0 0 0 0 0 5
1960/61 0 0 0 0 0 0 0 0 6 0 0 0 6
1961/62 0 0 0 0 0 11 4 2 1 0 0 0 18
1962/63 0 0 0 0 0 0 4 1 0 0 0 0 5
1963/64 0 0 0 0 3 0 2 2 3 0 0 0 10
1964/65 0 0 0 0 0 13 7 4 0 0 0 0 24
1965/66 0 0 0 0 0 1 6 2 8 0 0 0 23
1966/67 0 0 0 0 0 2 3 2 0 0 0 0 7
1967/68 0 0 0 0 0 1 5 5 0 0 0 0 11
1968/69 0 0 0 0 0 7 .; ,. 3 0 0 0 0 21
1969170 0 0 0 0 0 0 6 1 0 0 0 0 7
1970171 0 0 0 0 0 7 15 3 7 0 0 0 32
1971172 0 0 0 0 1 1 12· 4 10 0 0 0 28
1972173 0 0 0 0 0 o-13 2 0 0 0 0 15
1973174 0 0 0 0 1 1 5 2 6 0 0 0 15
1974175 0 0 0 0 0 2 9 4 2 0 0 0 17
1975176 0 0 0 0 0 11 2 0 0 0 0 0 13
1976177 0 0 0 0 0 0 0 0 0 0 0 0 0
1977178 0 0 0 0 0 8 0 0 0 0 0 0 8
1978179 0 0 0 0 0 0 0 6 0 0 0 0 6
1979/80 0 0 0 0 0 3 1 0 0 0 0 0 10
1980/81 0 0 0 0 0 8 0 0 0 0 0 0 8
1981/82 0 0 0 0 0 0 3 6 0 0 0 0 9
1982/83 0 0 0 0 0 0 4 0 0 0 0 0 4
1983/84 0 0 0 0 0 0 2 0 0 0 0 0 2
1984/85 0 0 0 0 0 0
AVG 0.0 0.0 0.0 0.0 0.3 3.3 4.8 2.8 1.5 0.0 0.0 0.0 12
MIN 0.0 0.0 0.0 0.0 0.0 o.o o.o 0.0 0.0 0.0 0.0 0.0 0
MAX 0.0 0.0 0.0 0.0 4.0 13.0 17.0 22.0 10.0 2.0 0.0 0.0 35
2-13
Table 2-4. Summary of wind data from the Homer WSO.*
Mean Maximum Maximum Maximum
Speed Prevailing Speed Speed Speed
Month (Mph) Direction (mph) Direction Year
January 8.0 NE 36 90 1980
February 8.0 NE 35 220 1981
March 7.6 NE 35 220 1975
April 7.6 NE 30 290 1985
May 7.9 sw 40 110 1975
June 7.3 WSW 31 130 1972
July 6.8 WSW 25 250 1982
August 5.9 WSW 32 280 1984
September 6.3 NE 36 90 1978·
October 6.9 NE 35 80 1978
November 7.6 NE 44 80 1983
December 7.4 NE 32 150 1982
Year 7.3 NE 44 80 1983
*Based on NCC, 1977, 1986
2-14
Table 2-5. Summary of precipitation data from the Homer WSO.
Mean Minimum Maximum Mean Minimum Maximum
Precipitation* Precipitation* Precipitation* Snowfall Snowfall Snowfall
Month (Inches) (Inches) (Inches) (Inches) (Inches} (Inches)
January 1.65 0.39 6.68 10.2 T 33.8
February 1.93 0. 12 5.62 12.~ T ~6.0
March 1.28 0.21 6.02 10.0 T 38. 1
April 1.31 0.01 3.~9 3.8 T 11.4
May 1.07 0.08 2.28 0.5 T 6.6
June 1.05 0.09 3.37 T 0.0 T
July 1.47 0. 16 3.79 0.0 0.0 0.0
August 2.36 0.47 5.56 0.0 0.0 0.0
September 2.86 0.83 5.30 T 0.0 0.5
October 3.28 0.91 8.55 2.5 0.0 21.9
November 2.91 0. 12 8.72 7.3 T 37.4
N December 2.58 0.00 8.01 12.9 0.~ 5~.7
I
t-'
1..11 Year 23.75 0.00 8.72 59.7 0.0 5~.7
• Water Equivalent
Table 2-6. Mean monthly streamflows* for the Bradley River at outlet of Bradley Lake (USGS, 1958-1985).
WATER MEAN
YEAR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL
1958 726 543 111 79 42 32 74 389 1260 1280 1550 405 541
1959 252 102 60 33 25 22 33 308 927 910 897 358 338
1960 174 94 60 39 35 24 33 593 812 1040 980 515 369
1961 232 141.! 179 199 107 1.!2 30 1.!36 850 1220 101.!0 1150 1.!71
1962 324 116 71 55 31 22 39 177 763 977 772 1.!58 319
1963 250 317 127 113 87 67 1.!5 237 705 1360 1330 1110 1.!82
1964 524 91.! 108 75 63 40 33 87 71.!7 1100 11.!1.!0 1040 1.!49
1965 1.!45 11.!0 85 61.! 50 55 75 131 593 1030 1100 1600 1.!1.!9
1966 555 165 70 39 32 31 1.!1 150 867 1020 1890 1670 51.!7
1967 1.!90 61.! 1.!3 35 31 29 36 253 811 1100 11.!00 1650 1.!97
1968 215 221.! 136 99 91 105 62 307 651.! 1010 111.!0 1.!62 378
1969 259 13 1.!1 35 35 31.! 1.!3 310 1520 1390 953 650 1.!47
I\) 1970 1720 211 239 118 116 109 103 331 803 1190 1270 675 579 I
1-' 1971 197 382 76 1.!5 36 31 31 115 61.!1 1391.! 1262 507 396
0\ 1972 376 108 55 32 20 17 17 11.!1 517 1172 1378 1019 1.!06
1973 1.!13 123 56 31.! 26 21.! 28 128 600 918 870 908 346
1974 575 173 50 32 23 19 23 227 551 860 1000 1501 1.!21
1975 31.!6 221.! 112 55 1.!3 34 30 355 1035 1068 861.! 850 1.!20
1976 424 118 52 39 32 26 1.!1 206 813 1107 1153 1293 1143
1977 1120 1.!111 312 326 306 178 119 351.! 995 1653 20119 6116 652
1978 1.!07 10 37 31.! 110 112 56 291 755 1081 1182 959 1115
1979 572 161 101.! 1.!3 30 27 31 290 712 1004 1883 1357 521
1980 1173 1.! 11 85 67 81 71.! 58 326 936 1332 13011 897 561.!
1981 779 150 110 233 160 170 310 788 908 11.!90 1643 885 640
1982 298 251 98 52 73 115 37 158 677 1107 901.! 1780 1157
1983 256 117 11.!6 123 68 47 48 337 777 892 130 1102 331
19811 310 305 192 77 58 1111 13 2511 683 861 1013 567 379
1985 416 92 911 181.! 93 31.! 31 190 614 977 796 651 350
Mean 469 192 101.! 811 65 54 56 280 805 1127 1207 927 1.!29
Minimum 174 70 37 32 20 19 17 87 517 860 730 1.!02 319
Maximum 1720 543 312 325 306 178 310 788 1520 1653 20119 1780 652
* All flows in cfs.
Table 2-7. Analysis of daily variations in winter flows from the
Bradley River at the outlet of Bradley Lake (SWEC, 1986).
Flow
Range Number of Days, 1957 to 1985
(CFS) DEC JAN FEB MAR APR
0 -100 576 703 701 755 763
100 -200 228 91 51 8B 6~
200 -300 3B ~7 2~ 25 0
300 -~00 15 20 13 1
~00 -500 3 6 2 ~
500 -600 ~ 1 ~
600 -700 1 ~
700 -BOO 1
BOO -900 0
900 -1000 2
1000 -1100
1100 -1200
1200 -1300
1300 -1~00
1~00 -1500
Count (Day) B6B B6B 791 B6B B~O
Average Flow
(CFS) 10~ B~.2 65.0 5~.~ 56.4
Maximum Flow
(CFS) 99~ 517 440 300 662
Minimum Flow
(CFS) 30 24 1B 16 16
Standard
Deviation Flow
(CFS) B6.9 79.8 61.5 49.0 67.2
2-17
Table 2-8. Summary of predicted pre-project mean monthly flows* (Ott Water, 1981).
Mean
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP Annual
Bradley River at Mouth 594 247 127 86 79 64 105 355 1,025 1 '337 1 1390 1,085 546
Flow to Upper Estuary
(Bradley River & Sheep
Creek) 2' 131 881 471 247 251 204 395 1' 161 3,003 3,896 3,626 3,267 1 '621
Fox River near Mouth 709 293 159 74.4 79.4 64.5 134 372 913 1' 181 1 ,032 1 ,007 496
Sheep Creek near Mouth 1 '537 634 344 161 172 140 290 806 1 '978 2,559 2,236 21 182 1 ,075
Battle Creek at Mouth 152 62.5 33.9 15.9 17.0 13.8 28.6 79.5 195 252 221 215 106
1\) Martin River at Mouth 212 87.3 47.4 22.2 23.7 19.2 40.0 111 272 352 308 300 148 I
1-1 co Total Flow into Upper
Kachemak Bay 3,204 1 '324 711 359 371 302 598 1,724 4,383 5,681 5' 187 4,789 2,371
* All Flows in CFS.
Totals and Means may not be exact due to rounding.
Table 2-9. Summary of water temperature (in °C) data for Bradley River at the outlet of Bradley
Lake (USGS, 1980-85).
WATER
YEAR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT
A. Minimum Temperature
1980 5.0 5.0 0.0 0.0 0.0 8.0 5.5 6.5
1981 5.0 1.0
1982 4.5 0.0 0.5 0.0 0.0 1.5 3.0
1983
1984 0.0 0.0 0.0 3.5 5.5
1985 0.0 0.0 4.5 8.0 8.0
Mean 4.8 2.5 0.3 0.0 0.0 0.0 0.0 3.5 4.9 5.5 1.2
N B. Maximum Temperature I
I-'
"" 1980 5.0 0.0 0.0 0.5 3.0 3.0 9.0 1.0
1981 6.5 8.0
1982 1.0 4.5 1.5 1.0 0.5 5.5 12.0
1983
1984 1.5 0.5 0.5 7.5 11.0
1985 0.0 0.0 4.5 11.5 11.0 9.5
Mean 6.2 4.5 1.5 0.8 0.3 0.0 0.5 5.0 7.8 10.7 8.2
Table 2-10. Summary of tidal datum for Kachemak Bay.
Seldovia Homer Halibut Cove
Datum* (feet 1 MLLW) (feet 1 MLLW) (feet 1 MLLW)
Highest Tide (Estimated) 23.0 24.8** 24.0
Mean Higher High Water 17.8 18. 1 18.2
Mean High Water 17.0 17.3 17.5
Mean Tide Level 9.3 9.5 9.6
Mean Low Water 1.6 1.6 1.6
Mean Lower Low Water 0.0 0.0 0.0
Lowest Tide (Estimated) -5.5 -5.6** -6.0
* Referenced to Mean Lower Low Water (MLLW) Datum except as noted.
1951a, 19516, 1967, 1968; APA (no date).
N
~ ** Measured.
0
Bear Cove ProJect Site
(feet 1 MLLW) (feet 1 MLLW) (feet 1 Project Datum)
25.0 25.0 11.37
18.5 18.4 4.78
17.6 17.6 3.97
9.6 9.6 -4.02
1.6 1.6 -12.02
0.0 0.0 -13.63
-6.0 -6.0 -19.63
Data sources are U.S. Coast & Geodetic Survey
Table 2-11. Summary of physical characteristics of Kachemak Bay (Knull,
1975).
Characteristic Inner Bay Outer Bay Entire Bay
Surface Area at High Water (m~2 ) 127 290 418
Surface Area at Low Water (mi ) 94 284 378
Intertidal Area (mi 2 )* 33 6 40
Mean Depth (feet) 92 129 118
Mean Tidal Range (feet)
Volume at High Water (ft3) 3.28x1o 11 1.05x10 12 15.9
1.37x1o 12
*Calculated from data by Knull (1975).
2-21
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Location map of study
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area.
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80~----------------------------------------------------------------------
MINIMUM
MAXIMUM
~ 40+--~~~~~~~~~~~-+--------------4-------------~~~~~~~--~ e_..
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~ ffi3o+---~~~~~~~~~~--~~--~~-4~-+~~--~~~~~~~~~~~
Q..
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~20+-~~~~~~~~~~~--~--~~~~~~~~~~~~~
::::E
JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN
MONTHS
JANUARY 21, 1987 : SWEC
Figure 2-2. Mean monthly air temperatures at the Homer WSO (from AEIDC, 1986).
,I'
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'
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·-
0 5 10
Scale in Nautical Miles
Figure 2-3. Generalized surface circulation patterns in Kachemak Bay (after Burbank, 1977).
SECTION 3.0
LOCAL INTERVIEWS
3.0 LOCAL INTERVIEWS
3.1 INTRODUCTION
Local interviews were conducted in Homer during the period of December
11-14, 1986, primarily to obtain information on ice and other oceano-
graphic/meteorologic conditions pertinent to the review of previous
investigations. During this period, a total of 16 individuals or
organizations were contacted; these are as listed on Table 3-1.
Questions asked by the interviewer were intended to determine as much
information as possible on the following specific points.
1. Description of the various types of ice and local terminolo-
gy,
2. Conditions under which the various types of ice form,
3. Locations where ice forms and occurs,
4. Movement of ice under varying meteorological and
oceanographic conditions,
5. Normal timing and distribution of ice,
6. Extreme ice events, and
1. Problems encountered by boats operating in ice conditions.
Additional information, such as the interviewee's occupation and length
of local residency, was also noted where appropriate.
Records documenting individuals discussions are provided in Appendix A
of this report. The following section describes the general and
specific findings and conclusions with regards to the local interviews.
2-1544-RW 3-1
3.2 RESULTS OF INTERVIEWS
3.2.1 General
Local residents provided significant personal observations and histor-
ical information related to normal and extreme ice conditions in
Kachemak Bay. Although there were some minor differences in some
specific items and especially in terminology from person to person, it
was felt that the general findings were consistent.
3.2.2 Types of Ice
Ice in Cook Inlet usually falls into four classifications: ( 1) sea
ice, (2) beach ice, (3) stamukhi, and (4) estuary or river ice. Based
on conversations with local residents, a fifth classification -drift
ice -may be appropriate for Kachemak Bay. Table 3-2 describes each of
these classifications. Since there appears to be no common local
nomenclature for types of ice occurring in Kachemak Bay, the classifi-
cations as outlined in Table 3-2 will be used throughout this report.
Additionally this terminology will also be consistent with most other
published literature.
Various project personnel also indicate that glacial ice has been
observed in and off the mouths of glacial fed streams. The appearance
of glacial ice is generally associated with periods of high river flow
during the summer and fall months and is probably a result of erosion
and calving along the toe of glaciers. The occurrence of glacial ice
in Kachemak Bay is not considered to be a significant winter problem,
nor one potentially associated with the Bradley Lake Project. As such,
it is not addressed further in this report.
3.2.2.1 Sea Ice
Most literature on Cook Inlet ice (including Hutcheon, 1972; LaBelle et
al., 1983) suggests that sea ice is the predominant type of ice in the
inlet. However, local residents suggest that sea ice is a much less
common form of ice in Kachemak Bay. With relatively warmer oceanic
waters in the bay, the surface water temperatures cannot be
sufficiently depressed, in most cases, to permit formation of
2-1544-RW 3-2
sea ice. As an exception, local residents describe sea ice forming in
shallower or relatively quiescent areas such as Mud Bay, the Homer
small boat harbor, or the numerous smaller bays and coves located along
the southern side of Kachemak Bay. While sea ice may reach thicknesses
of up to 6 feet in upper Cook Inlet, it is believed that sea ice in
Kachemak Bay seldom exceeds 1 foot in thickness (Moss, pers. comm.).
Typical thicknesses of sea ice in Kachemak Bay are probably 6 inches or
less (Bury, pers. comm. ; Anderson, pers. comm. ; Zawistowski, pers.
comm.; Strutz, pers. comm.).
3.2.2.2 Beach Ice
Based on the local interviews, it is believed that most ice observed in
Kachemak Bay initially formed as beach ice. Sheppard (pers. comm.)
suggests that beach ice may account for as much as 90 to 95 percent of
the ice generated. Most persons interviewed indicated that beach ice
forms either at the head of Kachemak Bay or in Mud Bay near the Homer
Spit. Typically, beach ice forms in layers up to 2 to 3 inches thick
per tide (Kilcher, pers. comm.; Zawistowski, pers. comm.) and can grow
to thicknesses of 2 to 3 feet (Moss, pers. comm.; Tillion, pers. comm.;
Sink, pers. comm.; Strutz, pers. comm.). Moss (pers. comm.) indicates
that this ice can be extremely hard, which may suggest that it could be
formed from either brackish water or freshwater.
3.2.2.3 Stamukhi
Although local residents do not use the term stamukhi, it is apparent
that this form of ice commonly occurs in Kachernak Bay. Starnukhi are
believed to be most commonly formed when one piece of beach ice is
deposited on top of another piece of beach ice. Commonly, this ice is
4 to 5 feet thick (Kilcher, pers. comm.; Choate, pers. comm.; Anderson,
pers. comm.; Moss, pers. comm.) and can achieve thicknesses up to 10
feet in extreme cases (Kilcher, pers. comm.). Anderson (pers. comrn.)
indicated individual blocks can be 20 to 30 feet across.
2-1544-RW 3-3
3.2.2.4 Estuary Ice
The terms estuary ice and river ice are often used interchangeably.
For the purposes of this discussion, estuary ice is defined as that ice
forming below the highest tidal elevation. At river mouths, estuary
ice may be fresh while in adjacent areas it may be brackish. River ice
is defined as that ice forming above the highest tidal elevations and,
as such, it will always be freshwater ice.
Although estuary ice probably occurs in Kachemak Bay, it is unclear as
to its extent and it is probably difficult to differentiate it from
other forms of ice present. Notable exceptions likely occur in the
smaller bays and coves along the southern margin of Kachemak Bay.
Sheppard (pers. comm.} reported that freshwater (estuary) ice can form
very rapidly to 1/2 inch or 1 inch thickness with cold, clear and calm
weather. He has heard of this type of ice forming 5 times since 1971
and has personally observed it twice along the south side of Kachemak
Bay. Sheppard's description of freshwater (estuary) ice matches well
with that of Zubov (1943) in that it is transparent and brittle.
3.2.2.5 Drift Ice
Drift ice is perhaps the most common ice encountered by vessel opera-
tors in Kachemak Bay. Based on descriptions by local residents, it is
believed to be a combination of all other forms of ice previously
mentioned. During periods of warm weather and high tides, ice may be
lifted off the beach and moved to deeper water. Most persons inter-
viewed indicated that northeast winds (which prevail during the winter)
carry the drift ice along the northern shore of the inner Kachemak Bay
where it tends to accumulate along the eastern side of the Homer Spit.
Drift ice will continue to build along the spit until it finally starts
to spill out into the outer Kachemak Bay and Cook Inlet where it
eventually melts. If colder weather occurs while drift ice is present,
it is possible for the ice to aggregate and freeze together as a solid
sheet. Winds with westerly components, however, tend to disperse the
drift ice (Bury, pers. comm.; Blanchard, pers. comm.).
2-1544-RW 3-4
3.2.3 Factors Affecting Ice Formation
Based on conversations with local residents, factors which appear to
influence ice include: temperatures, winds, snow, tides and freshwater
inflows. Nearly all resiJents interviewed associated ice formation
with cold temperatures and the northeast winds. Tillion (pers. comm.)
suggests that in the winter, colder air from Alaska's interior is
funnelled into the head of the bay. Kilcher (pers. comm.) and Tillion
(pers. comm.) both indicated that in the winter, temperatures are much
colder at the head of the bay, perhaps by 10°F or more, than at Homer.
While northeast winds normally accompany the movement of cold air
masses from Alaska's interior to Kachemak Bay, air temperatures appear
to be a more dominant factor in ice formation. It is normal for ice to
form any time air temperatures drop below 20°F (Bury, pers. comm.;
Choate, pers. comm.; Blanchard, pers. comm.). When temperatures drop
to 0°F, ice can be a problem, at least in the small boat harbor (Bury,
pers. comm.). During these colder periods when ice becomes a problem,
winds are typically calm (Moss, pers. comm.; Tillion, pers. comm.).
Sheppard (pers. comm.) indicated that the duration of cold weather is
important to the ice formation process.
The occurrence of snow also appears to influence the formation of ice
through a number of mechanisms. Anderson (pers. comm.) noted that when
you get "a lot" of snow, you also can get "a lot" of slush ice formed
in the open water. Snow on the beach will also form slush ice as the
tide comes in (Moss, pers. comm.; Anderson, pers. comm.).
Additionally, if snow is deposited on top of floating ice, it can be
depressed by the weight of the snow, flooded, and subsequently add to
the ice thickness as it refreezes (Anderson, pers. comm.).
Tides affect ice formation in several ways. With lower tidal ranges,
currents are normally lower and mixing of the water column may also be
reduced. This condition could allow more time for ice formation.
Additionally, higher tidal ranges can result in the breakage, removal
and/or movement of beach ice to higher locations on the beach (Choate,
pers. comm.; Zawistowski, pers. comm.; Tillion, pers. comm.).
2-1544-RW 3-5
Freshwater inflows probably influence ice formation at the head of
Kachemak Bay. Kilcher (pers. comm.), Sheppard (pers. comm.) and Moss
(pers. comm.) all indicated that freshwater ice (estuary ice) forms in
a number of the bays and coves along the southern side of inner
Kachemak Bay. Kilcher (pers. comm.) indicated that Halibut and Bear
Coves will freeze over occasionally, but that with more freshwater,
these coves froze over in less cold weather. Sink ( pers. comm.), a
helicopter pilot, indicated that he first notices ice around intertidal
channels at freshwater sources.
3.2.4 Ice Occurrence and Distribution
3.2.4.1 General
Ice conditions in Kachemak Bay, being dependent to a large extent on
weather, vary considerably from year to year. As such, it is somewhat
difficult to characterize "normal" ice conditions. Nevertheless, some
generalizations have been attempted.
Normally, ice can occur in Kachemak Bay any time during the months of
November through April. Strutz (pers. comm.) indicated that in some
years ice appeared and disappeared 3 or 4 times during these months.
Worst ice conditions occur during January through March (Anderson,
pers. comm.; Moss, pers. comm.; Blanchard, pers. comm.).
Based on local interviews, the past 10 years have been relatively mild
winters with limited ice conditions (Anderson, pers. comm.; Moss, pers.
comm.; Herring, pers. comm.; Tillion, pers. comm.; Strutz, pers. comm.;
Cunningham, pers. comm.). By comparison, the moderately cold winters
in the early 1970's caused moderate to large amounts of ice.
3.2.4.2 Mild Winter Ice Events
Figure 3-1 provides a representation of what is considered to be the
maximum extent of ice during mild winters (notable past 10 years). In
these conditions beach and drift ice forms first at the head of the
Kachemak Bay and in Coal and Mud Bays. Beach ice predominates at the
2-1544-RW 3-6
head of Kachemak Bay and can extend along the entire northern shore of
the inner Kachemak Bay to the Homer Spit. Drift ice predominates east
of the spit under the mild winter ice event. Ice can form within a
several week period and disappear nearly as rapidly given the right
temperatures and winds. In some confined areas with restricted circu-
lation, such as in the Horner small boat harbor, drift ice may pack in
and persist for longer periods of time.
3.2.4.3 Moderate Winter Ice Events
Figure 3-2 depicts the extent of ice for moderately cold winters (early
1970's). The ice edge extends further south along the entire inner bay
from the ice 1 irni ts shown for a mild winter. In a moderately cold
winter, ice may freeze together to form a relatively solid sheet. This
would be particularly evident in Coal and Mud Bays. During these
conditions, the small boat harbor would be frozen solid (a combination
of drift ice and sea ice) and most boats would have difficulties in
maneuvering into and out of the harbor.
3.2.4.4 Extreme Ice Events
Local residents indicate 8 or 9 times when ice conditions were consid-
ered to be particularly bad or extreme. These events are indicated on
Table 3-3. By far, the worst event recalled by most long term resi-
dents was that of February, 1947 (Kilcher, pers. comm.; Zawistowski,
pers. comm.; Tillion, pers. comm.). During this event, ice was report-
ed (Zawistowski, pers. comm.) to cover the entire inner bay east of a
line extending from the tip of the Homer Spit south (see Figure 3-3).
Zawistowski (pers. comm.) indicated that there was no ice movement
between the tip of the Horner Spit and Gull Island for a 2 week period.
Kilcher (pers. comm.) who also observed this event, indicated a
slightly lesser extent of ice cover, however, agreed with Zawistowski
that the ice generally occurred as a solid sheet of ice. The exact
extent of ice during other extreme events is not well known.
Zawistowski (pers. comm.), however, indicated that old timers indicated
to him that the only other time the bay completely froze over was in
1919.
2-1544-RW 3-7
Table 3-1. List of local residents contacted or interviewed.
INDIVIDUAL(S)
Joel Gay
John Bury
Larry Smith
Yule Kilcher
Mike Sheppard
Bill Choate
Virgo & Fred Anderson
Joel Moss
Gar land Blanchard-
Steve Zawistowski
Homer Museum
Bob Herring*
Clem Tillion*
Jim Sink
Louie Strutz
John Cunningham
* Conducted by telephone
COMMENTS
Homer Weekly News
Harbor Office, Resident since 1978
Steering Committee Member, Resident since 1968
Homesteader, Politics, Resident since 1944
Commercial Fishing, Resident since 1971
Commercial Fishing, Resident since 1947
Commercial Fishing, Residents since 1924
Commercial Fishing, Resident since 1946
Commercial Fishing, Resident since 1980
Fox Farm and Trapping, Resident since 1930
Photographic Documentation
Ship Pilot, Resident since 1971
Marine Operations, Resident since 1947
Helicopter Pilot, Resident since 1983
Resident since 1954
Resident since 1970
3-8
Table 3-2. Classification of ice in Kachemak Bay (modified from LaBelle et al., 1983).
CLASSIFICATION
Sea Ice
Beach Ice
Stamukhi
Estuary and River Ice
Drift Ice
DESCRIPTION
This type forms in seawater, first developing a thin crust on the surface and growing
through additions of ice to the bottom surface. Some local residents also refer to this
type of ice as sheet ice.
Large tidal fluctuations in the inlet account for the sudden appearance of a considerable
amount of ice on intertidal areas, particularly mudflats, in winter. The ebbing tide
exposes the mud to cold air, freezing the upper layer of mud and water or slush ice which
may remain in the intertidal area. Elsewhere in the inlet, growth may be as much as an
inch or more a day. Generally, however, a thickness no greater than about 1.5 to 2.0 ft
is reached before the ice is floated free of the mud. Some local residents also refer to
this type of ice as shore ice or anchor ice.
Stamukhi result from beach ice which has broken free and has been redeposited in the
intertidal soils or on other beach ice. This process can be repeated many times and is
limited only by the height of the tides and the strength with which the underlying ice is
frozen to the beach. In upper Cook Inlet, observers have seen stamukhi as thick as 20 ft.
Local residents normally refer to this type of ice as chuck ice or cake ice. (Note: no
locals used the term stamukhi).
These are both types of freshwater ice which form in the estuaries and rivers around Cook
Inlet. Estuary ice grows in the same manner as sea ice but is generally much harder.
River ice is unaffected by tidal action and normally remains in the rivers until spring
breakup. At that time, considerable quantities of river ice may be discharged into the
inlet. Some local residents refer to this type of ice as either freshwater ice or sheet
ice.
This ice is a combination of all the above types of ice. During relatively warmer periods,
drift ice may be loosely consolidated and move up and down Kachemak Bay until either it melts
or moves out of the bay. During colder periods and under some wind conditions, it can
consolidate and even freeze together as a solid mass. Local residents refer to this type of
ice as pan ice, floe ice, pancake ice or chunk ice.
w
I
!-'
0
Table 3-3. Summary of extreme ice events in Kachemak Bay.
TIME
1919
1932
About 1940*
1943
February 1947
March 1956
January 1971
1971/72 winter
1972/73 winter
COMMENTS
Entire inner bay froze over
Bad ice year
Dock destroyed by ice
Bad ice year
Entire inner bay froze over
and dock destroyed by ice
Dock destroyed by ice
Bad ice year
Bad ice year
Bad ice year
* May have been 1943 event
SOURCE(S)
Related by oldtimers to Zawistowski (pers. comm.)
Zawistowski (pers. comm.)
Anderson (pers. comm.)
Zawistowski (pers. comm.)
Kilcher (pers. comm.), Zawistowski (pers. comm.)
Anderson (pers. comm.)
Moss (pers. comm.)
Choate (pers. comm.)
Choate (pers. comm.), Tillion (pers. comm.)
..
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Scale in Nautical Miles
WJ Extent of Ice
,, . ..
•: ""' "
"'""""''•'·· ...... , '~'"""'' ..
b "
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.;; .. "
f{ \ ·,·.·
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Figure 3-1. Typical extent of ice during a mild winter (past 10 years).
w
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0 5
Scale in Nautical Miles
~ Extent of Ice
,.
,, .. ,,
"'···-,.,,,. ·'" ···•"""''"" .•
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Figure 3-2. Typical extent of ice during a moderate winter (early 1970's).
•. ,
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Scale in Nautical
~%;] Extent of Ice
"
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Figure 3-3. Reported extent of ice during February 194 7.
·,
'I'
SECTION 4.0
COLLABORATION AND
DISCUSSION OF
LOCAL INTERVIEWS
4.0 COLLABORATION AND DISCUSSION OF LOCAL INTERVIEWS
4.1 GENERAL
Information collected during the local interviews added significantly
to the existing published data ~n ice types, ice formation processes,
and the winter extent of ice in Kachemak Bay. This section discusses
the information collected and relates it to the existing data base.
4.2 ICE TYPES
As previously indicated, sea ice is the predominant type of ice which
occurs in the upper and central Cook Inlet (Hutcheon, 1972; LaBelle et
al., 1983). Based on the local interviews, sea ice is not a
predominant form of ice in Kachemak Bay. Water temperatures in upper
Cook Inlet are typically at or slightly above freezing for much of the
winter; as such, sea ice can readily form even when the air tempera-
tures drop slightly below freezing. By comparison, Kachemak Bay
receives a significant inflow of warmer oceanic waters on a continuing
basis even during the winter, and circulation patterns are fairly
effective in mixing these waters throughout the bay. As a result,
water temperatures are generally much warmer in Kachemak Bay than in
the upper inlet. In order for sea ice to form in Kachemak Bay, the bay
waters must first be cooled. As a result, colder weather must persist
for a much longer time before sea ice can form in Kachemak Bay.
Ice types which are more prevalent in Kachemak Bay are characteristic
of a coastal environment which is subject to cyclical events of above
and below freezing weather. In this case ice forms in areas which
respond most rapidly to the temperature fluctuations. These include
the tidal flats (beach ice) and in and adjacent to river mouths
(estuary ice). Tides, currents, and/or warming weather may move this
ice to open water (drift ice) or deposit it elsewhere on the beach
(stamukhi).
1-1544-JW 4-1
4.3 FACTORS AFFECTING ICE FORMATION
4.3.1 General
Based on local interviews, air temperatures are the primary factor
influencing Kachemak Bay ice conditions. Other factors include winds,
tides, circulation patterns, snow and fresh water inflows. These are
discussed in the following sections.
4.3.2 Air Temperatures
Numerous residents indicated that ice conditions result in the bay
during extended periods of cold weather. Although persistence data are
not readily available for the Homer WSO temperature data, statistical
summaries previously presented in Table 2-2 (days below 32°F} and Table
2-3 (days below 0°F} are useful.
Figure 4-1 provides a graphical presentation of data previously
summarized on Table 2-2. If one ignores years when data are incomplete
(1934-35, 1937-38, 1972 and 1984}, actual variation in the annual days
below 32°F from year to year is relatively slight. It was, however,
noted that the number of days annually below 32°F have been below the
average of 188 days since the winter of 1975/76. This tends to support
the observation that temperatures have been warmer than normal for
approximately the past 10 years.
Figure 4-2 provides a graphical summary of the number of days below
0°F. On the average, there are about 12 days per winter when air
temperatures at Homer fall below 0°F. Extremes of record ranged from 0
days per year to 35 days per year. It is interesting to note that the
extreme ice year of record (winter of 1946/47) also had the maximum
reported days with temperatures below 0°F. The two other years,
1942/43 winter and 1955/56 winter, when the Homer dock was reportedly
destroyed by ice (see Table 3-3) also had particularly cold winters (31
and 32 days below 0°F, respectively). The winter of 1970/71 was the
only other winter having over 30 days with 0°F weather, and it also was
indicated to a severe ice year (Table 3-3}. During other bad ice
•'
years, ( 1931/32}, 1971172, and 1972173 winters}, the number of days
1-1544-JW 4-2
below 0°F were all above normal. As with Figure 4-1, Figure 4-2 also
tends to confirm that the past 10 years have had relatively mild air
temperatures.
Several local residents also observed that winter temperatures were
colder at the head of the bay than at Homer. Although measured data
are not available to confirm this observation, ARCTEC ( 1985)
hypothesized that strong wintertime southwesterly winds observed at
Homer are unable to penetrate far into Kachemak Bay due to persistent
northeasterly flow of cold air. As a result of this condition, winds
would be from opposing directions between the head of the bay and
Homer, and air temperatures would be colder at the head of the bay.
Possible temperature differentials between the two locations were not
addressed by ARCTEC (1985).
4.3.3 Tides and Currents
Tides and currents can both promote and retard ice formation. Ice
growth can be promoted when the tidal flats become exposed to colder
winter air temperatures. With cold temperatures, intertidal areas can
be cooled to below freezing temperatures and during the subsequent
rising and falling of the tide, moisture remaining on the beach can
freeze. Local residents indicated several inches of ice can readily
form on the beach with cold temperatures. This agrees with
observations reported by LaBelle ·et al. ( 1983) which indicate that
beach ice growth can be as much as an inch or more per day in upper
Cook Inlet. Local residents also indicate that beach ice is typically
2 to 3 feet thick. LaBelle et al. (1983) indicates that at a thickness
of 1.5 to 2.0 feet, beach ice in the upper inlet usually floats free of
the mud. It is hypothesized that at this thickness, the upward
buoyancy of the ice (when submerged by high tide) is sufficient to
break any bonds between the bottom of the beach ice and the underlying
beach soils. After beach ice breaks free it may either float to open
water (drift ice) or be redeposited elsewhere in the intertidal area
(stamukhi).
1-1544-JW 4-3
The rate of beach ice formation is to some degree a function of the
elevation on the beach. Areas of the beach which are at lower tidal
elevations are exposed to the air for shorter durations, while
locations at high tidal elevations {say around MHHW elevations) may be
exposed to cold air for periods of a day or more. In these areas ice
may form more rapidly when again exposed to water from the tidal
fluctuations. This process would tend to confirm several local
resident observations that beach ice tends to be thinner at the lower
intertidal elevations.
Higher tides and currents are also reported by some residents to retard
the formation of ice. While there is no direct data to support this
conclusion, it is hypothesized that the higher tides result in higher
currents which in turn increase the turbulence and mixing of the water
column. The enhanced mixing would tend to disperse colder surface
waters {which are exposed to the air) into the underlying warmer
waters. Although it is likely that ice can eventually form given
enough cold air temperatures, higher tides and currents can delay the
freezing process.
Most local residents interviewed indicated that drift ice normally
moves from the head of the inner bay and is transported along the
northern shore and accumulates east of the Homer Spit. Of the
approximately 33 mi 2 of intertidal area within the inner bay,
approximately 35 percent occurs along the northern shore. Assuming
that most drift ice is derived from beach ice which forms in these
intertidal areas, circulation patterns suggested by Burbank (1977) and
Gatto (1981) both support this local observation.
4.3.4 Freshwater Inflows
The role of fresh water is perhaps the least documented of factors
relevant to ice formation in Kachemak Bay. Freshwater effects can be
significant, particularly since freshwater will freeze at higher
temperatures (32°F) than saltwater (about 29°F). While this 3°F
freezing temperature differential is not really large, it is sufficient
1-1544-JW 4-4
to affect the time required to produce freezing. Given exposure to a
similar air temperature, fresh water will freeze more rapidly than salt
water.
Within the inner bay, fresh water may be derived either from river
inflows or from precipitation. During the winter months of October to
April, river inflows at the head of the bay (from Table 2-8) provide an
average of 1.81x10 10 rt3 of fresh water to the inner bay.
Precipitation provides a corresponding volume of 4.42x1o9 ft3 of fresh
water, including 1. 15x109 ft3 directly on the intertidal area. The
primary effect of the fresh water input would be the dilution of the
saline inner bay waters (a volume of about 3.28x10 11 ft3 at high tide).
Since the mixing process cannot occur instantaneously, depressed
salinities are more likely to be observed located at the river mouths
and at the water's surface. Areas with depressed salinities (and
elevated freezing temperatures) would typically freeze prior to areas
of higher salinities.
Although many residents recognize that ice forms first at the head of
the bay, few indicated a specific association between winter freshwater
inflows and ice formation. As previously indicated, the effects of
fresh water inflows and estuary ice formation may be, to a large
degree, indistinguishable from beach ice and drift ice. Several
persons interviewed did however relate fresh water inflows to ice
formation in a number of the smaller bays and coves along the south
side of the inner bay.
generally limited.
In these regions, intertidal areas are
Several residents indicated that when snow is present on the intertidal
area, slush ice can form on the incoming tide. As the tide recedes,
slush and trapped water may be left on the intertidal area where it
can be exposed to freezing air temperatures. It is hypothesized that
this process could help to promote initiation of beach ice formation.
1-1544-JW 4-5
,j::o,
I
0'1
m =-some data missing
2&0
22&
,.-...200
Ll-
0 ............
N ,.., 17&
3:
0 Ld 1&0
m
lD
Li...l
0:::: 12& ;:;
ffi1oo
0...
1_!1
~ 7&
~ 0 &0
2&
m m
0
32 37 42 47 52 57 62
YEARS
1932 -1983
67
m
72 77 82
JANUARY 21, 1967
Figure 4-1. Annual number of days when the air temperature at the Homer WSO dropped below
3 2 o F ( AE I DC , 1 9 8 6 ) •
.Po
I
-.J
m =-some data missing
<40
3~
,--..,. t3o
0
:;::
g 25 w m
w
0::: 20 ~
m
w
~ 1~
~ 10
0
5 m
0
m OmO.o f.1
32 37 42 47 52 57 62
YEARS
1932 -1983
67
0
72 77 82
JANUARY 21 , 1 98
Figure 4-2. Annual number of days when the air temperature at the Homer WSO dropped below
0 o F ( AE I DC, 1 9 8 6 ) •
SECTION 5.0
REVIEW OF PREVIOUS
PROJECT REPORTS
5.0 REVIEW OF PREVIOUS PROJECT REPORTS
5 . 1 BACKGROUND
A number of studies have been undertaken which are directly related to
the Bradley Lake Project. Studies which are key to this review are
summarized in the following reports.
1. "Circulatiof'! Studies in Kachemak Bay and Lower Cook Inlet" by D.C.
Burbank ( 1977).
2. "Circulation and Dispersion of Bradley River Water in Upper
Kachemak Bay" by J. M. Colonell ( 1980) .
3. "Ice Distribution and Winter Surface Circulation Patterns,
Kachemak Bay, Alaska" by L.W. Gatto (1981).
4. "A Theoretical Investigation of the Potential Modifications of Ice
Formation in Kachemak Bay by the Bradley Lake Hydroelectric Power
Project" by J.P. Gosink and T.E. Ostercamp (1981).
5. 11 Prediction of Ice Growth and Circulation in Kachemak Bay, Bradley
Lake Hydroelectric Project" by S.F. Daly (1981).
These five studies are considered to be the most important to
discussions on potential effects of the Bradley Lake Project. Each of
these reports is discussed and critiqued in the following sections.
5.2 BURBANK CIRCULATION STUDIES
Burbank (1977) provides the results of a comprehensive study of surface
and subsurface circulation patterns in Kachemak Bay. The methodology
used in the study is generally accepted practice and the data appear to
be sound. When conclusions are made, limitations are generally stated.
1-1544-JW 5-1
Although data were collected over the entire year (see discussion
Section 2.4.4), the author indicates that his inferred circulation
patterns are somewhat biased towards spring and summer conditions.
Even with these limitations, the results of Burbank (1977) are believed
to provide an accurate representation of the generalized circulation
patterns in both the inner and outer Kachemak Bay for the entire year.
We see this report as an excellent data source.
5.3 COLONELL CIRCULATION AND DISPERSION STUDIES
Colonell ( 1980) conducted dispersion studies in August, October and
November, 1980. The stated purpose of these studies was to define the
circulation and dispersion of the Bradley River discharge in Kachemak
Bay under both summer and winter conditions.
Based on our review of the Colonell study in combination with
discussions with the report author, we would conclude the following:
1 . The general study design is a valid approach for measuring the
dispersion of a discharge into another body of water; and if
successfully implemented, it could also be used to provide an
estimate of the rate of mixing between fresh and marine waters.
2. Although the field data were limited due to logistical
constraints, they did provide useful information which in
combination with professional judgment could be used to form
general conclusions with regards to the mixing of fresh and marine
waters.
3. The conclusion of near total mixing within 3 or 4 tidal cycles
appears to be based to a large degree on professional judgment;
based on our understanding of conditions at the head of the bay,
this rate of mixing appears to be generally reasonable.
1-1544-JW 5-2
4. Finally, we would also concur with the author that detailed
mapping of the salinity and temperature structure in the area of
interest may provide additional information for quantification of
the mixing process.
5.4 GATTO STUDIES
Gatto (1981) reports investigations to describe winter surface
circulation and document ice distribution patterns in Kachemak Bay
using satellite photography. As part of this study, 51 satellite
images taken between November and April 30 were analyzed for each of
eight winters between 1972 and 1980. From these analyses, Gatto
observed the following:
1. Winter circulation in the inner bay is predominantly counter-
clockwise (supporting the findings of Burbank, 1977).
2. Most of the ice in the inner bay forms at its northeast end near
the mouths of the Fox, Sheep, and Bradley Rivers.
3. Some ice becomes shorefast on the tidal flats at the head of the
bay, while some moves southwestward along the north shore pushed
by winds and currents.
4. When drifting ice reaches Coal Bay, it accumulates between the
Homer Spit and the north shore. lt1 Ls buildup extended out to the
tip of the Homer Spit in February 1976 and 1979.
5. Ice was not observed along the south shore of the inner bay.
6. Surface circulation patterns could generally not be observed in
the outer bay.
1. Ice was not observed in the bay on November imagery and most ice
was gone by mid-April.
1-1544-JW 5-3
Gatto's observations are useful for describing the occurrence and
distribution of ice in Kachemak Bay. While the satellite imagery
provides an excellent means to document circulation patterns and the
extent and distribution of ice at any one time, it is only
representative of conditions at a single point in time. As such, some
care must be used if one intends to use those data to assess ice on a
statistical basis. As an example, assuming that each photo was
representative of conditions on a single day, the 51 photos analyzed
would only represent ice conditions for less than 4 percent of the time
(6 months for 8 years}. In addition, photos were not distributed
evenly throughout the winter due to either ambient light or cloud
cover; no imagery was available for the month of December and only two
were available for January. Given that these large gaps occur in the
data base, ice could have formed and melted without being noted (based
on comments by local residents).
Overall, we found the Gatto report to be informative. Comments
regarding the statistical evaluation of satellite imagery data
discussed in the preceding paragraph are intended to limit the data's
use for its intended purposes. All comments and uses of data presented
in the Gatto report appear correct and appropriate.
5.5 GOSINK AND OSTERCAMP STUDIES
Gosink and Ostercamp (1981) used a thermodynamic model for Kachemak Bay
ice production. Their investigation assessed changes in ice conditions
associated with the Bradley Lake project.
Based on our review of the report and subsequent correspondence from
the authors we would conclude that alternate approaches should be
considered. These include:
1. Considerations for the effects of intertidal cooling and beach ice
formation,
2. Consideration of a smaller control volume, and
1-1544-JW 5-4
3. Use of lower tailrace temperatures as input to the modelling
effort.
These items are discussed in the following sections.
By design, the Gosink and Ostercamp study did not consider the effects
of intertidal cooling (due to tidal fluctuations) and beach ice
formation. Based on conversations with local residents and a review of
other data, these mechanisms are believed to be very important for
production of ice in the inner bay.
Gosink and Ostercamp used the entire inner bay as a control volume for
balancing heat fluxes in their equations. Most ice formation presently
occurs at the head of the inner bay, presumably because oceanographic
and thermodynamic conditions are different in this region than those
occurring generally within the inner bay. As such, the use of a much
smaller control volume with more site specific input conditions is
believed to be more appropriate.
The Gosink and Ostercamp report assumed a tailrace discharge
temperature of 3 to 4°C (37° to 39°F), which appears to be high. Water
temperatures at the tailrace should be a function of the ambient lake
temperature and any heating as the water passes through the tunnel and
powerhouse. Based on winter profiles of Bradley Lake ( COE, 1982) ,
winter temperatures at depths of 50 to 150 ft (depth of the intake)
will range from about 0.6 to 3.6°C (33° to 38°F); these data were
reportedly not available to the authors for their analysis. In order
to provide a conservative estimate of potential impacts, the lower
values of this range should be assumed. Water temperature increases in
the tunnel have been calculated by SWEC personnel; based on our review
of their analysis we would concur with their conclusion that an
increase in the range of 0. 1 to 0. 5°C ( 0. 2° to 0. 9°F) is probably
realistic. As such, we feel that discharge temperature more in the
1-1544-JW 5-5
order of 0. 7 to 1 . 0°C ( 33° to 34°F) should have been assumed for the
Gosink and Ostercamp analyses instead of their assumed temperature of 3
to 4°C (37° to 39°F). Based on preliminary calculations discussed in
Section 7.0, the discharge water temperature would only be important in
considerations of ice formation within the tailrace.
5.6 DALY REPORT
Daly ( 1981) provides a summary of the potential for ice growth and
circulation in Kachemak Bay and describes how these relate to the
Bradley Lake Project. Although specific references are not mentioned,
it appears that this report in part provides a summary of data and
analyses reported by Gatto (1981) and by Gosink and Ostercamp (1981).
These studies have been discussed in some detail in the preceding
sections.
There were a number of conclusions provided in the Daly report which we
feel are supported based on information summarized in previous sections
and results of preliminary calculations discussed in Section 7.0.
Specific conclusions related to existing conditions include:
1. Ice in Kachemak Bay can be a result of ice discharge from rivers
and streams flowing into the bay, anchor ice (beach ice) growth in
the tidal flats, sheet ice growth, and frazil ice growth.
2. Most ice in the inner bay forms at the mouths of rivers on the
northeast end. Some ice becomes shorefast on the tidal flats at
the head of the bay, while some moves southwestward along the
north shore pushed by winds and currents. When ice reaches Coal
Bay, it accurnula tes between the spit and the north shore of the
inner bay.
Daly also provides a number of conclusions with regards to potential
ice formation from the Bradley Lake which are also believed accurate.
These include:
1-1544-JW 5-6
1. Estimates of rates and accumulation of ice in Kachemak Bay are at
best deductions reached from theoretical analysis. Empirical
evidence to support these deductions is limited.
2. Anchor ice (beach ice) growth on the tidal flats could be
increased by the operation of the project.
3. Frazil ice formation appears to be the only way in which present
ice production rates could be significantly altered by a larger
winter discharge. Factors which are expected to affect frazil ice
formation include the dilution of salt water with freshwater,
temperature of the freshwater, and degree of mixing or
stratification.
While frazil ice (slush ice) is probably an important mechanisms for
ice formation at the head of the inner bay under existing conditions,
it is believed that frazil ice occurs for only a short duration. Given
the high tidal fluctuations and extensive intertidal areas at the head
of the bay, it is believed that most frazil ice rapidly becomes
deposited on the beaches during ebbing tides where it then accumulates
as beach ice. Alternatively, frazil ice may agglomerate in open water
where it forms pans or drift ice.
1-1544-JW 5-7
SECTION 6.0
EXISTING HYDROPOWER
PROJECT CASE HISTORIES
6.0 EXISTING HYDROPOWER PROJECT CASE HISTORIES
6. 1 BACKGROUND
A review of available data and information sources was undertaken to
identify any existing hydropower projects of comparable climatic and
geographic conditions to the Bradley Lake Project. The primary
objective of this review was first to identify hydropower projects
which discharge to arctic or subarctic coastal areas, and second to
determine whether icing problems developed as a result of winter
discharges from these facilities. Specific case histories are
presented to summarize conditions at specific facilities.
6.2 INFORMATION SOURCES
6.2.1 General
Information was obtained both from a review of existing published
literature and by conversations with persons who operated or design
hydropower plants in arctic or subarctic areas. Each of these are
described briefly in the following sections.
6.2.2 Literature Review
Available literature was obtained and/or identified from three sources
as indicated below:
1. Delft Hydraulics Laboratory files (located in the Netherlands),
2. NORTEC 1 s internal references and data sources, and
3. Discussions with individuals involved with hydropower projects.
The Delft Hydraulics Laboratory maintains a library of international
data on coastal and riverine hydraulics and engineering. Information
and specific reports may be identified and obtained utilizing the Delft
Hydro Database. For this study, the Delft Hydro Database was used to
identify published information, referenced to the following key words:
1-1544-JW 6-1
estuaries, hydroelectric power plants, ice control, ice cover, ice
prevention, tailraces, and tidal inlets. From this search, 17 reports
were identified. Based on an examination of those titles, 9 were
obtained and reviewed for this study.
NORTEC maintains a library of published and unpublished literature for
arctic and subarctic areas. These data were also reviewed and four
additional reports were obtained.
Individuals contacted as part of the review process (as discussed in
the following section) were asked whether reports existed to describe
icing conditions at specific facilities. Additional relevant
literature was not identified as a result of these conversations.
A total of 13 reports or publications were obtained as part of the
literature review, and these are listed in Table 6-1. Three
publications were in French; these were not translated but were instead
reviewed by personnel fluent in the language.
6.2.3 Individual Contacts
A number of individuals were contacted by telephone to provide
information on specific projects. These individuals are typically
associated with either the design or operation of hydropower projects
in arctic and subarctic conditions (principally in Canada). A list of
individuals contacted are summarized in Table 6-2.
6.3 CASE HISTORIES
6.3.1 General
A total of 41 hydropower projects were identified during the literature
review and individual contacts; these are summarized in Table 6-3. Of
these, 15 were located in the USSR, 3 in Norway, 21 in Canada and 2 in
the United States {Alaska).
1-1544-JW 6-2
Of the projects listed, 16 were considered to be coastal facilities and
the remaining projects were located on rivers inland from the coast.
The inland facilities are discussed only in general terms while the 16
coastal projects are summarized in more detail.
6.3.2 Inland Hydropower Projects
Information on inland hydropower projects in the USSR was obtained
primarily from published literature. Gotlib et al. (1983) provide a
general discussion of ice conditions downstream of hydropower plants in
the USSR. A total of 15 different plants were identified, all of which
occur on rivers (see Table 6-2). Although specific descriptions were
not provided for each project, a number of observations of downstream
ice conditions were discussed in general terms. Briefly summarized
these include:
1. Ice thicknesses in reservoirs are typically thicker (by as much as
75~) than in the river downstream.
2. Open water areas were observed for distances of 2 to 225
kilometers downstream during the coldest months.
3. Freezeup was delayed by 5 to 10 days and breakup occurred 5 to 10
days earlier on rivers downstream of the hydropower projects;
these effects were reported to occur up to 900 kilometers
downstream.
4. Water stages caused by ice jamming were reduced for distances up
to 750 kilometers downstream.
Korzhavin (1983) provides additional discussions on the ice regimes in
reservoirs for three of the inland projects in the USSR. Karnovich et
al. ( 1983) describes some specific considerations and problems with
winter operation of an inland pumped-storage power plant in the USSR;
most problems were associated with ice and snow drift formation in
canals when they are not in use. Skladnev and Lyapin (1983) summarize
1-1544-JW 6-3
the general status and direction of ice engineering investigations in
the USSR; these investigations are broadly grouped as follows:
1. Ice covered flow hydraulics,
2. Ice and thermal conditions in reservoirs, headwaters and
tailwa ters,
3. Ice damming and jamming in rivers and reservoirs,
4. Thermal conditions for hydropower pipelines,
5. Physical properties of fresh water and sea ice,
6. Ice loads on hydraulic structures, and
7. Ice protection for hydraulic structures.
Information on inland Canadian hydropower projects was obtained
primarily from individual contacts. Five of the Canadian projects
(Churchill Falls, Deer Lake, Mactaquac, Revelstoke and Mica) reported
no ice problems. Four of the projects (Kettle, Janpeg, Peace Canyon
and Jim Shrum) indicated problems with frazil ice formation downstream
of the facility. The Jenpeg Project cuts back flows in the fall until
an ice cover develops in order to minimize frazil ice formation. The
Peace Canyon and Jim Shrum facilities also regulate flow both during
freezeup and breakup for frazil ice control. The Beachwood Project
reports to have problems with anchor ice formation downstream as a
result of peaking character is tics of the plant; this is reportedly
controlled by flow regulation during breakup and freezeup.
6.3.3 Coastal Hydropower Projects
A total of 16 hydropower projects were identified to be located at or
near the coast. Three were located in Norway, 11 in Canada and two in
Alaska. Each of these are summarized in the following paragraphs.
1-1544-JW 6-4
6.3.3.1 Norwegian Facilities
The Vangen Power Station was a hydropower facility proposed to be
constructed in the Aurland Fjord. Water from the facility was to be
discharged through two outlets, 10 to 12 feet in diameter, at a depth
of approximately 60 feet. Saegrov (1978) used scaled hydraulic models
and analytical methods to hypothesize effects for the then proposed
facility. Primary concerns were to define operational limits necessary
to prevent ice formation in winter months. Saegrov (1978) found that
higher velocities provided more intense mixing of the freshwater and
saltwater; as such, flows were increased for decreasing air tempera-
tures. Reported operational flows for the facility during cold
temperatures ranged from about 1,300 cfs at -1°C (30°F) to 2,650 cfs at
-10°C (14°F). Because of the method of discharge, this facility would
probably not be comparable to the Bradley Lake Project.
The Rana Project is a hydropower facility on the Rana River at the head
of the Rana Fjord. Winter discharges as a result of the facility were
2 to 3 times the normal inflow; experience in an adjacent arm of the
fjord suggested that ice would form unless the river water was mixed
with the saline fjord water. Carstens (1971) describes the air bubbler
system which was designed to force rapid mixing of freshwater and salt
water. In the actual operation, two perforated parallel pipes about
1,300 ft long were suspended at a depth of 50 ft across the mouth of
the Rana River through which compressed air was pumped. Fresh water
normally flows into the fjord as a surface jet at velocities up to 1.25
knots at the falling tide, and salinities less than 10 ppt for a design
discharge of approximately 7,100 cfs. The intent of the bubbler system
was to increase the average surface salinity to about 25 ppt which
would reduce the vertical stability to allow mixing by natural
processes to prevent freezing. Carstens ( 1971) indicated that three
seasons of successful operation have suggested that forced mixing with
the air bubbler system is somewhat effective under some oceanographic
conditions. Sufficient information (particularly on the fjord
configuration) is not provided in the available literature to ascertain
whether this facility would be comparable to the Bradley Lake Project.
1-1544-JW 6-5
The Loen Power Station is a hydropower facility located in Nordfjord.
Although details of this facility are not available, Carstens and Rye
( 1979) reported that upon construction, the formerly ice-free fjord
developed an ice cover. Carstens and Rye (1979) also reviewed various
means of controlling impacts of changes in fjords as a result of
increased fresh water discharges in winter hydropower development.
They concluded that the primary objective in any solution to the
problem is to dilute the water as rapidly as possible. Three options
were considered to meet this objective:
1. Discharge the freshwater as a submerged jet,
2. Mixing of a surface jet using an air bubbler system, or
3. Induced mixing with propellers to drive vertical jets
Sufficient information is not provided in the available literature to
determine whether discharge conditions for this project would be
comparable to the Bradley Lake Project.
6.3.3.2 Canadian Facilities
The Tidewater Plant is a 6 MW hydropower facility located on the coast
of Nova Scotia. Winter discharges are approximately 1,400 cfs. Some
shore ice is reported to occur, but anchor ice and frazil ice have not
been noted. Turbulent flow in the tailrace mixes the freshwater and
saltwater. The seawater does not freeze in the area. Reports for this
facility are not available. Since the seawater does not freeze in the
area, climatic and oceanographic conditions are probably not comparable
to the Bradley Lake Project.
The Weymouth Plant is a 18 MW hydropower facility located on the coast
near Weymouth, Nova Scotia. Winter discharges are approximately 3,500
cfs. Some shore ice is reported to occur, but anchor. ice and frazil
ice have not been noted. Turbulent flow in the tailrace mixes the
fresh water and salt water. The seawater does not freeze in the area.
1-1544-JW 6-6
Reports for this facility are not available. Since the seawater does
not freeze in the area, climatic and oceanographic conditions are
probably not comparable to the Bradley Lake Project.
The Leqville Plant is a 10 MW hydropower facility located on the coast
of Nova Scotia. Winter discharges are approximately 400 cfs. The
tailrace never freezes and there are no reported ice problems. Reports
for this facility are not available. Climatic and oceanographic
conditions at this site are believed to be not comparable to the
Bradley Lake Project.
The Tusket Plant is a 2.7 MW hydropower facility located on the coast
near Tusket, Nova Scotia. Winter discharges are approximately 700 cfs.
Ice problems have not been reported at this facility. Reported for
this facility are not available. Climatic and oceanographic conditions
at this site are not believed to be comparable to the Bradley Lake
Project.
The Ruth Falls Plant is 7.5 MW hydropower facility located on the coast
near Annapolis, Nova Scotia. Winter discharges are approximately 1,400
cfs. There are no reported ice problems downstream of the plant.
Reports for this facility are not available. Climatic and
oceanographic conditions at this site are not believed to be comparable
to the Bradley Lake Project.
The Annapolis Plant is a 20 MW tidal power facility located on the Bay
of Fundy in Nova Scotia. Winter discharges are approximately 106,000
cfs. There is continuous mixing of freshwater and saltwater and no ice
problems are reported on the sea side. Any shore ice which may form is
broken up by tides. Reports are not available for this facility.
Because of the nature of this facility, it is not believed to be
comparable to the Bradley Lake Project.
The Outardes Plant No. 2 is a 400 MW hydropower facility located at the
Outardes River Delta in Quebec. Winter discharges are approximately
40,000 cfs. Some problems have been reported with anchor ice due to
1-1544-JW 6-7
daily fluctuations in discharge, and a study is currently underway to
address this problem. Climatic and oceanographic conditions at this
site are not believed to be comparable to the Bradley Lake Project.
The Marric River Plant No. 1 is a 2,020 MW hydropower facility located
on the Marric River near the coast of Quebec. Winter discharges are
approximately 35,000 cfs. There is some open water during winter but
an ice cover on the salt water. Frazil and anchor ice problems are not
reported. No reports are available for the facility. Climatic and
oceanographic conditions at this site are not believed to be comparable
to the Bradley Lake Project.
The Bay D'Espoir Plant is a 600 MW hydropower facility located at the
head of a 10 mile long bay in Newfoundland. Winter discharges are
approximately 12,000 cfs. The 1.5 mile long discharge channel
reportedly stayed open during winter; but the bay freezes over
completely in winter. Winter air temperatures at the site are
typically 10 to 20°F, and the coldest temperatures are about 0°F. The
salinity of the bay is believed to have dropped considerably. No
reports are available for this facility. Although the tailrace
discharge is considerably greater than anticipated for the Bradley Lake
Project, there may be some merit to a closer examination of this
facility.
The Cat Arm Plant is a 128 MW hydropower facility located on the coast
of Newfoundland. Winter discharges are approximately 1,200 cfs. There
are no reports of ice problems downstream due to the high exit
velocities in the tailrace. Reports are not available for this
facility. In many respects, this project appears to be fairly
comparable to the Bradley Lake Project. However, since ice doesn't
appear to have been a problem prior to the project construction, there
may be some differences in climatic or oceanographic conditions between
the sites.
The Alcan Project is a 800 MW hydropower facility located near Kemano,
British Columbia. Winter discharges are approximately 4,000 cfs and
flow into the Kemano River at least several miles up from the river
1-1544-JW 6-8
mouth. Normal winter temperatures range from 25 to 32°F with an
extreme low temperature of -13°F. No ice problems have been reported.
Reports are not available for this facility. This facility is not
believed to be similar to the Bradley Lake Project because of the
discharge rates and conditions.
6.3.3.3 Alaskan Facilities
The Snettisham Project is a hydropower facility located at the head of
Speel Arm in southeastern Alaska. The project has a designed capacity
of 47 MW. Discharges in the winter range from about 250 cfs at night
to 500 or 550 cfs during the day. The tailrace discharges to Crater
Cove which is mostly intertidal and adjacent to the mouth of the Speel
River. Ice never forms in the tailrace but occasionally shore ice and
estuary ice (up to a maximum of 3 or 4 inches) can form in Crater Cove
during cold weather (average of 3 to 4 days per winter). By
comparison,
conditions.
flow from the Speel River can cause more serious ice
The less severe ice conditions in Crater Cove are
attributed to the warmer water temperatures (1.5 to 3°C) in the
tailrace. Although the tailrace flows are lower and the climate is
likely to be slightly warmer than at the Bradley Lake Project, the
tailrace discharges to an intertidal area which is similar to the
Bradley Lake Project.
The Eklutna Project is a hydropower facility located near the mouth of
the Knik River and head of Knik Arm in Cook Inlet. The project has a
capacity of 32 MW and during winter, discharges typical range up to 500
or 550 cfs. Water temperatures normally range from about 3°C in the
winter to 6°C in the summer. Water from the facility flows through a
canal to a channel of the Knik River; during winter months the Knik
River channel commonly only has water discharged from the power plant.
The canal never freezes up and the Knik River channel usually has open
water all the way to Knik Arm. Because of the differences in the
tailrace location and configuration, this project is not believed to be
similar to the Bradley Lake Project.
1-1544-JW 6-9
0\
I
1-'
0
TABLE 6-1. List of reports and publications obtained during the literature review.*
Author(s)
Carstens
Carstens and
Rye
Foulds
Gotlib et al.
Haynes et al.
Karnovich et al.
Korzhavin
Marcotte
Pekhovitch and
Catalina
Pruden et al.
Saegrov
2-1544-KB
Date
1971
1979
1981
1983
1981
1983
1983
1981
1970
1954
1979
Title
Prevention of ice information by forced mixing.
Controlling impact of changes in fjord hydrology
Peaking hydro generating stations in winter
Change of river thermal regime in relation to
construction of hydroelectric plants under severe
climatic conditions.
Performance of a point source bubbler under thick ice
Winter operation of pumped storage power plant basins
and canals
The effect of hydroconstruction on the ice regime of
some Siberian rivers
Thermal regime and ice regime in rivers (in French)
Control of frazil ice formation downstream from power
plants situated at river months (in French)
A study of wintertime heat losses from a water surface
and of heat conservation and heat addition to combat
ice formation in the St. Lawrence River
Prevention of freezing in fjords
Source
NORTEC
Delft
Delft
Delft
Delft
Delft
Delft
Delft
NORTEC
NORTEC
Delft
0'\
I
1-'
1-'
Table 6-1. List of reports and publications obtained during the literature review.•
(Continued)
Author(s)
Skladnev and
Lyapin
Votruba and
Matousek
Date
1983
1970
Title
Ice engineering investigations in the USSR -Present
state of the art
L'assurance de !'alimentation ininterrompue par
l'amenee d'eau ouverte en hiver (in French)
• Complete citations provided in Section 9.0 Bibliography.
2-1544-KB
Source
Delft
NORTEC
Table 6-2. Individuals contacted as part of the review.
INDIVIDUAL
Mr. Doug Hayward
Mr. Horton
Mr. John Hallam
Mr. Tom Wigle
Mr. F. Fonseca
Mr. Rick Carson
Mr. Roy Smith
Mr. Robert Keyes
Mr. Adrian Chandler
Mr. J. Farina
Mr. L. Parmley
Mr. R. Rayban
Mr. Larry Gerard
Mr. Tom Spicher
Mr. Stan Sieczkowski
2-1544-KB
AFFILIATION
New Brunswick Hydro
Nova Scotia Power Corp.
Newfoundland Hydro
Ontario Hydro
Hydro Quebec
Acres Engineering
Saskatchewan Power Corp.
Trans Alta Utilities
Crippen Consultants
Alcan
British Columbia Hydro
and Power Authority
Manatoba Hydro
University of Alberta
Alaska Power Administration
Alaska Power Administration
6-12
LOCATION
Fredericton, New
Brunswick
Halifax, Nova Scotia
St. John's, Newfoundland
Toronto, Ontario
Montreal, Queberr
Winnipeg, Manitoba
Regina, Saskatchewan
Calgary, Alberta
Vancouver, British
Columbia
Kitimat, British
Columbia
Vancouver, British
Columbia
Winnipeg, Manatoba
Calgary, Alberta
Juneau, Alaska
Palmer, Alaska
Table 6-3. List of hydropower projects identified as a result of the literature review and individual contacts.
Project
Novosibirks Hydropower Plant
Bratsk Hydropower Plant
Ust-Ilim Hydropower Plant
Irkutsk Hydropower Plant
Boguchan Hydropower Plant
Zeya Hydropower Plant
Krasnoyarsk Hydropower Plant
~ Sayano-Shushenskaya Hydropower
w Plant
Mainskaya Hydropower Plant
Ust-Kamenogorsk Hydropower Plant
Bukhtarma Hydropower Plant
Vilyui Hydropower Plant
Gorky Hydropower Plant
Nizhne-Burejskaya Hydropower
Plant
Kegum Hydropower Plant
2-1544-KB
Location
Ob River, Siberia
Angara River
Angara River
Angara River
Angara River
Zeya River
Yenisei River
Yenisei River
Yenisei River
Irtish River,
Siberia
Irtish River,
Siberia
Vilyui River
Bureya River
Daugawa River
Country
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
USSR
Reference(s)
Gotlib et al. (1983);
Korzhavin (1983)
Got lib et al. (1983)
Gotlib et al. (1983)
Got lib et al. (1983)
Gotlib et al. (1983)
Gotlib et al, (1983)
Got lib et al. (1983)
Got lib et al. (1983)
Gotlib et al. (1983)
Gotlib et al. (1983);
Korzhavin (1983)
Gotlib et al. (1983);
Korzhavin (1983)
Got lib et al. (1983)
Gotlib et al. (1983)
Gotlib et al. ( 1983)
Gotlib et al. (1983)
Table 6-3. List of hydropower projects identified as a result of the literature review and individual contacts.
(Continued)
Project Location Country Reference(s}
Vangen Power Station* Aurland Fjord Norway Saegrov (1978)
Rana Hydropower Project* Rana River/Fjord Norway Carstens ( 1971)
Loen Power Station* Nordfjord Norway Carstens and Rye (1979)
Tidewater Hydropower Plant* Coast of Nova Canada Horton (pers. comm.)
Scotia
Weymouth Hydropower Plant* Coast of Nova Canada Horton (pers. comm.)
Scotia
Leqvllle Hydropower Plant* Coast of Nova Canada Horton (pers. comm.}
Scotia
Tusket Hydropower Plant* Nova Scotia Canada Horton (pers. comm.}
Ruth Falls Hydropower Plant* Coast of Nova Canada Horton (pers. comm.}
Scotia
Annapolis Tidal Plant* Bay of Fundy, Canada Horton (pers. comm.)
Nova Scotia
Beachwood Hydropower Plant St. Johns River, Canada Hayward (pers. comm.)
New Brunswick
Mactaquac Hydropower Plant St. Johns River, Canada Hayward (pers. comm.)
New Brunswick
Outardes Power Plant No. 2* Outardes River Canada Fonseca (pers. comm.)
Delta, Quebec
Marric River Plant No. 1* Marric River at Canada Fonseca (pers. comm.)
Coast, Quebec
2-1544-KB
Table 6-3. List of hydropower projects identified as a result of the literature review and individual contacts.
(Continued)
Project
Churchill Falls Hydropower Plant
Deer Lake Hydropower Plant
Bay D'Espoir Hydropower Plant*
Cat Arm Hydropower Plant*
Alcan Hydropower Plant*
Revelstoke Hydropower Plant
Mica Hydropower Plant
Jim Shrum Hydropower Plant
Peace Canyon Hydropower Plant
Jenpeg Generating Station
Kettle Power Station
Snettisham Hydropower Project*
Eklutna Power Project*
Location
Churchill River,
Laborador
Inland Newfoundland
1 . 5 Mi. Inland,
Newfoundland
Coast of Newfound-
land
Kemano, British
Columbia
Columbia River,
British Columbia
Columbia River,
British Columbia
Peace River,
British Columbia
Peace River,
British Columbia
Nelson River,
Manitoba
Nelson River,
Manitoba
Southeast Alaska
Southcentral Alaska
* Coastal projects; case histories provided.
2-1544-KB
Country
Canada
Canada
Canada
Canada
Canada
Canada
Canada
Canada
Canada
Canada
Canada
USA
USA
Reference(s)
Hallam (pers. comm.)
Hallam (pers. comm.)
Hallam (pers. comm.)
Hallam (pers. comm.)
Chautler (pers. comm.);
Farina (pers. comm.)
Parmley (pers. comm.)
Parmley (pers. comm.)
Parmley (pers. comm.)
Parmley (pers. comm.)
Rayban (pers. comm.)
Carson (pers. comm.)
Spicher (pers. comm.)
Sieczkowski (pers. comm.)
SECTION 7.0
REVIEW OF
PROPOSED OPERATIONS
7.0 REVIEW Or PROPOSED OPERATIONS
1. 1 BACKGROUND
7.1.1 General
The primary concern and focus of this specific task is to review the
design of the tailrace and planned discharges to determine modifi-
cations which could minimize potential icing problems should they
occur. These modifications may either be non-structural, such as
modification of flows; structural, such as modifications to the
tailrace design; or a combination of both.
Based on conversations with SWEC personnel (Bishop, pers. comm.; risk,
pers. comm.) a number of configurations have been considered for the
Bradley Lake tailrace. These include:
1. Conceptual tailrace configuration,
2. Preliminary engineering tailrace configuration,
3. Alternate tailrace configuration, and
4. Present design tailrace configuration
The evolution to the present design has been a fairly long and involved
process including considerations for ice formation, improved hydraulic
performance, and to address unique foundation conditions and
environmental effects. These are briefly summarized in the following
sections.
7.1.2 Conceptual Tailrace Configuration
The conceptual design for the tailrace is depicted on rigure 7-1. This
design basically included a basin 90 feet wide and 200 feet long at an
elevation of -6 feet BLPD (Bradley Lake Project Datum) with an fan
extending some 300 feet into the tidal flats at an elevation of 5 feet
BLPD. This conceptual design was configured to reduce turbulence from
the powerhouse discharge and spread the flow over a large area of the
tidal flats in order to minimize erosion.
1-1544-JW 7-1
The primary advantage of this design was that it minimized downslope
disturbance of the tidal flats in the vicinity of the powerhouse. The
primary concern with this design was that ·it would deposit water
directly at the top of the tidal flats in a thin layer where it could
be subject to freezing.
7.1.3 Preliminary Engineering Tailrace Configuration
The tailrace design developed during preliminary engineering is
depicted on Figure 7-2. This design was similar to· the conceptual
design except that a 800 foot long channel, 50 feet wide and at an
elevation of 2 feet BLPD was added to divert flows to a tidal slough.
While this design appeared to offer definite advantages for hydraulic
performance and icing control, it required a considerable disturbance
of the tidal flats.
7. 1.4 Alternate Tailrace Configuration
An alternate to the preliminary engineering tailrace configuration
which was considered is indicated on Figure 7-3. Under this
alternative design, the fan was eliminated and the powerhouse outlet
reduced in size to 150 feet in length. This alternate design
considerably reduced the disturbance to the tidal flats.
Both the preliminary engineering design and the alternate design were
eliminated based on geotechnical considerations. Soils investigations
along the tailrace indicated that the bedrock surface present at the
powerhouse extended at depth of approximately 20 to 35 feet below the
tidal flats. Groundwater perched on top of the bedrock surface was
reported to produce an artesian water pressure which caused sands to
flow when drilled through. Based on conversations with SWEC personnel,
excavations to 2 feet BLPD could result in instability in the tailrace
channel bottom and side slopes.
7.1.5 Present Design Tailrace Configuration
The present design for the tailrace is depicted on Figure 7-4. Under
this design, the powerhouse outlet includes a ramp 90 feet wide at the
powerhouse, 210 feet long, and widening to 176 at the start of the
1-1544-JW 7-2
tailrace canal. A canal, approximately 900 feet long and at an
elevation of 3.5 feet BLPD, delivers the flow to the tidal slough.
This design requires a .greater disturbance of the tidal flats than the
other alternatives, but it also avoids the problems with soil stability
in the narrower and deeper canals.
7.2 FACTORS PERTINENT TO THE REVIEW
7.2.1 General
In the project review it should be noted that information required to
make a complete evaluation of the va~ious alternatives is not
available. As an example, it is not known specifically what the
tailrace discharges will be. Additionally, some of the mechanisms
pertinent to a defensible assessment for ice information are still
somewhat unclear. The following paragraphs describe what basic
assumptions were made in assessing modifications to the proposed
operations.
7.2.2 Discharges
Based on discussions with SWEC personnel (Bishop, pers. comm.), once
the reservoir has achieved its operational capacity, it is planned to
operate year round but to have a full reservoir of 284, 150 acre-feet
(1.23x1o 10 ft3) available for winter discharge by the first of
November. This water would then be released through the winter months
until about mid-May when reservoir levels would again be r1s1ng (e.g.,
inflows to the reservoir would be greater than the outflows). Although
discharge of this volume of water would result in an average winter
flow of 735 cfs at the tailrace, actual flows may be as great as 1,500
cfs for short periods of time. These latter values have been assumed
for purposes of discussion.
7.2.3 Oceanographic Conditions and Ice Formation
The review of other hydropower projects suggests estuary and/or beach
ice can develop as a result of increased winter discharges. The
primary concern in Norwegian projects is estuary ice formation. In
these projects it was believed that ice formation could be minimized by
dilution of the freshwater discharge with the ambient seawater;
1-1544-JW 7-3
Carstens (1977) suggested that in achieving a salinity of about 25 ppt,
most ice formation could be controlled. At Canadian facilities, beach
.ice formation appeared to be the primary problem; although no solutions
were suggested for its control.
Based on local resident interviews, beach ice is a common form of ice
in Kachemak Bay. Given the large tidal fluctuations, the proximity of
extensive tidal flats to the proposed tailrace discharges, and the
general circulation patterns; the potential for beach ice formation
exis~s. During extremely cold periods (characterized by below 0°F
temperatures, clear. skies and calm winds) it is assumed that estuary
ice may possibly form.
7.2.4 Thermodynamic Considerations
A number of preliminary calculations were made to obtain a rough
appreciation of the relative importance of various parameters on the
systems thermodynamics. This technique is often referred to as a
parametric analysis. This analysis included:
1. Preliminary calculations of volumes of fresh water and salt water
invloved in nearfield mixing to determine a mixed water salinity
and temperature.
2. Estimates of freezing points for the mixed water masses.
3. Estimates of heat losses from the intertidal area from exposure to
cold air.
4. Estimates of heat losses from the mixed water mass to the
intertidal area during submergence.
5. Estimates of heat losses from the mixed water mass to the air.
6. Estimates of heat losses from the fresh water discharge to the air
in the tailrace.
1-1544-JW 7-4
Based on this analysis the following were determined to be important
considerations with respect to the thermodynamic analysis:
1. Fresh water discharge rates, bathymetric configuration at the head
of the bay and tidal fluctuations control the rate and degree of
mixing.
2. Seawater salinities, fresh water discharge rates and mixing time
control the mixed water mass salinity.
3. Water temperatures of the mixed water mass and water depths
control the timing for the initiation of freezing.
4. Salinities of the mixed water mass control the freezing point of
the mixed water. Fresh water, which has a higher freezing point
than salt water, would freeze before salt water.
5. Air temperatures, cloud cover, and wind speeds control the heat
losses from the surface of the mixed water masses.
6. Air temperatures and thermal properties of the intertidal soils
control the cooling of the intertidal areas.
7. Heat losses to the air and to the intertidal areas can result in
ice formation.
Preliminary calculations indicate that freezing can occur at the water
surface (estuary ice), within the water column (frazil ice), or on the
intertidal soils (beach ice} both with and without the tailrace
discharges. Effects of increased tailrace discharges appear to
slightly reduce the mixed water salinity and slightly increase the
mixed water temperature, at least when considering the head of the bay
above Chugachik Island (near field). The reduction in salinity would
permit freezing to occur at higher temperatures. The increase in
temperature would tend to slightly delay the timing of freezing. While
the combined effect has not been calculated, trends observed in the
1-1544-JW 7-5
preliminary calculations suggest that ice formation would occur
slightly earlier than would occur without the tailrace discharge and
would persist for a slightly longer duration.
Preliminary calculations indicate,
estimate, if complete mixing occurs
bay freezing effects would probably
that as an order of magnitude
fairly rapidly at the head of the
be defined in terms of hours. If
mixing were less rapid, effects would likely be defined in terms of
days.
7.3 POTENTIAL PROJECT MODIFICATIONS
Based on a review of the Bradley Lake Project, modifications made to
the tailrace design to date are believed to have reduced the potential
for ice formation. Based on a review of site conditions, local
interviews, review of existing reports, and the review of other
hydropower projects, it is believed that there is some potential for
formation of beach ice and perhaps, to a lesser degree, the potential
for estuary ice formation.
Effects, if they occurred, would be greatest in the intertidal areas
adjacent to the tailrace. It is not believed that ice will form
directly in the tailrace. Although specific effects have not been
quantified, they would likely include ice formation at less severe
winter temperatures and persistence of ice for a slightly longer
duration. While measurable effects may occur locally at the head of
the bay, it will be difficult to quantify or document effects at Homer,
some 20 miles from the tailrace.
The most direct way to minimize the potential for ice formation is to
reduce tailrace discharges during periods of severe cold weather.
While guidelines for reducing flow cannot be established based on
existing information, local residents indicate ice can be a serious
problem when air temperatures drop to 0°F or less. Based on historical
weather data, this can occur an average of approximately 12 days per
1-1544-JW 7-6
winter and up to 35 days for the extreme winter of record -1946/47.
During these periods, tailrace discharges could either be significantly
reduced, or stopped completely.
Based on the preliminary calculations, the rate of mixing of the
seawater and fresh water appears to have a large effect on the
potential for and timing of ice formation. With more rapid and
complete mixing, the potential for ice formation appears to be reduced.
Although sufficient information is not available to assess specific
tailrace design modifications, modifications which would provide
enhanced mixing, such as discharging the fresh water in deeper water,
may also reduce the potential for ice formation.
It should be emphasized that it is not known if increased winter
discharges will modify existing ice conditions. Based on preliminary
calculations, ice formation could occur slightly earlier and persist
for a slightly longer duration. Effects if they occurred would depend
on the degree of mixing and would likely be defined in terms of either
hours or days. Before project mitigation measures are implemented,
additional studies as outlined in Section 8.0 are recommended.
1-1544-JW 7-7
0
0
0
1.[)
N
(Y")
w
~~.J ·.~
N 2130000 c1
X 5.4
()
~~·· (~I~ ~ N : ~ '-'..JJ ~ J
.·
··.~6.4
111 = 200'
CONCEPTUAL TAILRACE
CONFIGURATION
FIGURE 7-1
0 6] ~ ~ .J
[;j rl ·-~·
\ ol t···~~
. (Y)
·2.);!_
~
c;l
N2130000
()
~~--,~,~ ~ (\j ·. ~ ---:. ); [;j J
X 5.4
111 = 200'
PRELIMINARY ENGINEERING
TAILRACE CONFIGURATION
FIGURE 7-2
0
0
0
L[) (\J
('f)
w
~~__; -~
N 2130000 N
X 5.4
)
_./
(\ ~~-(~,,~ ~ (\JI ·.
. Cj j
·-.~6.4
EL2
rl ( rr=. • . • • ,zyY~~L
111 = 200'
ALTERNATE TAILRACE
CONFIGURATION
FIGURE 7-3
0
0
0
1.[)
(\J
(Y)
w
~~ ... J ·.~
N 2130000
\ ol t··~~
. (Y)
"?)2
Cl
X 5.4
()
~~· (~)~ ~ (\J : ~ '-'_,./; i:j ,j
.·
··.~
X 6.4
EL 3.5
111 = 200 1
PRESENT DESIGN
TAILRACE CONFIGURATION
FIGURE 7-4
... ~
l
tf
...
,
~/··
' ~
r' •
~·
\:
\
.,;'. ' :.>y' c .
r•
l ' . -J: ·~ , .c ....... ~-~H-
'· !!. .... "' \.. . -~·~: ~ :"~-.,
~: -II
..... t'
' "<
... -
""
111
N
("")
w
... v ... :J
+..~ ..... .f
~
':-t•' • ' ~ ~~!a~i~ ·• ,<! ~-\, ~
.._ ........ ..,.._I \_ .... .
' ' . ~ . ..... .,.. ..
\ .
,_ ..
',"c
.....
:y:t
\. ...
~ • .
"' '
~ ... _,
' ;·>.·
.II" -
... .l .... ··~ ,,. ; ,\.""'!.
\.J.:\. >l'f'~)IS,. ... ?t:
Figure 7-5. Configuration of the proposed tailrace
and discharge canal.
.,.)
<'
.
(!)
N
("")
w
~
..,
PQWERHOUSE
ACCESS ROAD
PLATE 20
I'
N
("")
w
0 500 1000
• • • I C!,..,..l..,.. in ~,..,,..+
1-0)
1'\1
1'\1
C'1
w
Figure 7-5. Configuration of the proposed tailrace
and discharge canal (cont' d).
pir'•'
0 500 1000
~ • ._ I
Scale in Feet
SECTION 8.0
BASELINE DATA
COLLECTION AND
ADDITIONAL STUDIES
8.0 BASELINE DATA COLLECTION AND ADDITIONAL STUDIES
8.1 GENERAL
Based on local resident interviews, it is apparent that substantial ice
can form naturally within the inner bay during the winter. Ice types
which appear to be common for the inner bay primarily include beach ice
and drift ice, and to a lesser extent estuary ice and stamhukhi. Drift
ice and stamhukhi appear to be derived to a large extent from beach
ice. Previous ice formation investigations were limited primarily to
estudry ice. Additional studies are necessary to assess conditions
which presently promote the formation of ice (beach ice in particular)
to determine if after the project begins operation, there is indeed a
change in conditions.
A three phased approach for assessment of the potential for ice
formation is recommended (see Figure 8-1). Phase I would include an
assessment of ice formation processes at the head of the inner bay
in the vicinity of the proposed tailrace (nearfield). Problems, should
they occur, would be most evident in this nearfield area. If there is
sufficient potential for additional ice formation, Phase II should be
implemented. This would include a baseline data collection program
primarily to more accurately define various parameters which would be
important to reassess the potential for nearfield ice formation. If
there is still a significant potential effect, then a farfield ice
transport model (Phase III) is recommended to predict potential effects
for the entire inner bay, and specifically at the Homer Small Boat
Harbor.
While the scope of the Phase I studies can be established in some
detail, the scope of later phases depends to a large extent on
preceding efforts. As such, the specific requirements fo~ Phase II and
II I as outlined in the following sections may be subject to later
modification. Post-project monitoring, if required, would be similar
in scope as those outlined in Phase II.
1-1544-JW 8-1
8.2 PHASE I -NEARFIELD ICE FORMATION MODELING
8.2.1 Purpose
The basic purpose of the nearfield ice formation model is to refine the
preliminary thermodynamic calculations discussed in Section 7.2 .4 to
provide an estimate of the likely magnitude of potential effects from
the additional freshwater discharges on ice formation at the head of
the inner bay. Effects, if they occur, would be easiest to document in
the vicinity of the discharge.
8.2.2 Methods
The nearfield modeling effort should consider the thermal balance for
the area of the inner bay east of Chugachik Island. Four major tasks
as discussed in the following paragraphs are anticipated for this
effort.
As a first step various equations need to be formulated to describe the
thermodynamic processes important for ice formation on the bottom,
within the water column, and at the water surface. Based on the
preliminary calculations these would include:
1. Heat loss from the water surface to the air,
2. Heat loss from the exposed intertidal area to the air,
3. Heat loss from the water column to the submerged intertidal areas,
4. Heat transfer between water masses if stratification occurs, and
5. Variation in freezing temperatures as a result of varying
salinity.
Physical conditions, such as monthly variations in tidal ranges and
mixing of the fresh water and salt water are considered to be
particularly important.
1-1544-JW 8-2
Once the specific equations have been developed, sensitivity tests
should be conducted to determine the relative effect of varying input
parameters. The sensitivity tests should result in an identification
of those parameters which control ice formation processes. In
addition, baseline data requirements should be clearly identified as
part of this effort.
Summaries of meteorological and oceanographic data presently exist to
describe normal and extreme variations for most input conditions. In
the modeling effort actual hourly and daily data would need to be
collected as input values. Most of these data are in archives of the
federal government and would require some time and effort to retrieve.
Actual modelling effort should be conducted to predict effects under a
variety of normal and extreme conditions with and without the
discharges. To the extent possible, extreme ice events as noted by
local residents should be modeled and results verified where possible.
Ice events as depicted on satellite imagery may be used to calibrate
the model under normal or mild ice conditions.
8.2.3 Timing
Nearfield modeling efforts could be conducted in 1987 using existing
data. If the baseline data collection efforts are conducted, the
nearfield modeling could again be used to reassess potential effects.
Results of ice surveys, as discussed in following sections could also
be used to provide additional data for verification and calibration of
the nearfield model.
8.3 PHASE II -BASELINE DATA COLLECTION
8.3.1 General
Phase II efforts should be conducted if the results of the nearfield
ice modeling suggest that significant effects could occur. In order to
provide basic data for further analysis, we would recommend
consideration of the following three tasks:
1-1544-JW 8-3
1. Collection of meteorological data at the tailrace site to verify
temperature differences between the site and Homer.
2. Collection of additional data to define stratification and mixing
at the head of the inner bay.
3. Document and sample the various types of ice to confirm mechanisms
for ice formation.
Each of these additional studies are discussed in some detail in the
following sections.
Until a problem can be clearly defined, post-project data collection
cannot be justified at this time. Additionally, the specific scope of
individual studies may be modified slightly depending on the results of
Phase I activities.
8.3.2 Meteorological Data Collection
8 . 3 . 2 . 1 Purpose
The primary purpose for collecting meteorological data at the head of
the bay is to document differences in winter air temperatures between
the head of the bay and the Homer WSO for which a long term record
exists. A number of local residents indicate that temperatures can be
significantly colder in that area, and correlations in air temperatures
between the head of the bay and Homer would be used to synthesize a
long term record for the head of Kachemak Bay. This in turn would be
used to provide more accurate input to the nearfield ice formation
model.
8.3.2.2 Methods
Ambient air temperature data should be collected near sea level
elevations in the general vicinity of the tailrace during the winter
months. As a minimum, these data should include daily records for
maximum and minimum air temperatures. This may be accomplished simply
by installation of a standard weather shelter and a maximum/minimum
1-1544-JW 8-4
thermometer. Daily readings could be obtained during this period by
personnel available at the existing construction camp. If data could
alternately be obtained remotely and continuously using a number of
data acquisition systems and sensors designed for subarctic
environments, the accuracy of air temperature measurements should be
within~ 0.5°C (~1°F). This accuracy can be obtained using a number of
commercially available systems.
It is also our understanding that at least several years of
meteorological data exist for Halibut Cove. These data and any other
similar data for other regions of the inner bay should be reviewed in
detail and correlated with the longer term records for the Homer WSO.
Data collected at the meteorological station should be processed to
report either hourly air temperatures or daily values for the minimum,
maximum and mean air temperatures. All historical data from the Homer
WSO and the Halibut Cove stations should also be obtained from the
National Weather Service and reported in a similar format as data
collected from the station at the head of the bay.
8.3.2.3 Timing
The air temperature monitoring program should be implemented as soon as
possible and continue for at least one full winter. The specific
period of interest extends from November 1 , 1987 through April 30,
1988.
8.3.2.~ Other Considerations
It is our understanding that a meteorological station will soon be
operational at Sheep Point to collect data on wind speed and direction
and precipitation. This station will also collect water temperature
data in the tidal slough near the barge dock.
8.3.3 Oceanographic Data Collection
8.3.3.1 Purpose
The degree of stratification at the head of a water mass such as
Kachemak Bay can provide an indication of the degree of mixing between
1-1544-JW 8-5
the fresh and marine water masses. The degree of mixing will to a
large extent describe dilution of freshwater inflows, particularly in
winter. This in turn can be used to describe the potential for ice
formation within the inner bay.
Previous observations on winter oceanographic conditions are generally
limited as such collection of additional information on water column
structure and stratification is believed to be warranted.
8.3.3.2 Methods
Salinity and temperature profiles should be obtained to define existing
stratification during two periods in the winter. During each sampling
period, profiles should be obtained at 25 stations along 5 transects
within the inner bay {as indicated on Figure 8-2). These transects
should be obtained during both high and low stages to obtain variations
in stratification over the tidal cycle. If stratification is found to
extend further throughout the inner bay, then additional stations may
be warranted.
Within each profile, sufficient measurements of salinity and
temperature should be obtained to adequately describe the structure of
the entire water column. Salinity measurements should be accurate to
at least 0.1 ppt and temperature to at least 0.1°C (0.2°F). A number
of systems are available commercially which meet these specifications.
During each survey period discharge data for the Bradley River, wind
data, and tidal fluctuations should also be obtained. The U.S.
Geological Survey currently operates several gaging stations on the
Bradley River and these data should be obtained. Wind data shall be
obtained for the survey period both from the Homer WSO and monitoring
station at Sheep Point. Tidal data might be available from Homer;
however, if not, provisions should be made to monitor data on at least
an hourly basis during the period of survey (either at Homer at the
head of the bay). Tidal data should be referenced to Mean Lower Low
Water datum.
1-1544-JW 8-6
Data collected should be provided both in a tabular and graphical form.
Tabular data should include listings of all data collected along with
the corresponding tidal stage and discharge for the time of
observation. Graphical representations of the data should include
cross-sections of the bay showing salinity and temperature contours.
Additionally, a map should be prepared which shows the depth to the
thermocline at both the high and low tide.
8.3.3.3 Timing
Two surveys should be conducted during the winter of 1987/88. The
first survey is to be conducted in early winter (November 1987} and the
second in mid-to late winter (February to March 1988).
8.3.4 Ice Sampling
8 • 3 • 4 • 1 Purpose
One of the key questions remaining to be answered is whether beach ice
is formed from fresh, brackish or salt water. In actuality, it is
expected that all forms can exist along the shores of the bay.
Nevertheless, it is recommended that ice samples should be obtained of
various types of ice found along the head and northern shore of the
inner bay to provide an approximation of the various types of ice which
can occur. This information should be relatively simple to obtain and
can aid greatly in understanding the process of ice formation.
Additionally, data collected during these surveys could be used to
calibrate the nearfield ice formation model.
8.3.4.2 Methods
Measurements and samples of various types of ice should be obtained at
appoximately 12 stations as indicated on Figure 8-3 along the shore
extending from near the mouth of the Martin River to the Homer Spit.
Samples should be obtained for 5 replicate locations at each station
from the apparent near surface and near bottom of the ice. These
samples should be described visually and then thawed for salinity
measurements. If more than one type of ice occurs, then replicate
1-1544-JW 8-7
samples should be obtained for each type of ice. Each sampling site
should be described and documented photographically. Ice temperatures
should also be obtained if possible.
8.3.4.3 Timing
The ice survey is to be conducted at least once during the 1987/88
winter. It is desirable to obtain samples at a time when ice is
actually forming. As such, some coordination with local residents or
SWEC personnel will be required. It is also recognized that the past
10 years have been relatively mild and data may not be obtained for all
areas of the shoreline of interest. Depending on the results of the
initial sampling, additional sampling may be required.
8.4 PHASE III -FARFIELD ICE TRANSPORT MODELING
8.4.1 Purpose
Modeling efforts in Phase I and II were intended to describe effects of
ice formation at the head of the inner bay. If these modeling efforts
suggest that significant effects occur in the near field, then a more
extensive numerical modeling effort may be warranted to determine if
effects are significant at Homer.
8.4.2 Methods
The farfield ice transport model would in essence be an expanded
version of the nearfield ice formation model and would cover the entire
inner bay. In addition, it would be coupled with a numerical
hydrodynamics model which predicts two-or three-dimensional
circulation patterns in the inner bay. Selection and calibration of an
appropriate hydrodynamics model would in part be dependent on the
results of baseline studies.
1-1544-JW 8-8
8.4.5 Timing
The farfield ice transport model requires the input from Phase II
efforts. As such it could not be conducted until at least the spring
of 1988.
8.5 SUMMARY
As previously indicated, the scope of Phase I studies can be
established in some detail. Phases II and III have been described to
the extent possible at this time. As each phase is completed, each
subsequent study program should be reevaluated. Also, mitigation plans
would be updated and further defined.
1-1544-JW 8-9
(X)
,I
I-'
0
PHASE I
NE ARFIELD
ICE ASSESSMENT
( 1987)
PHASE II
BASELINE
OAT A COLLECTION
AND ASSESSMENT
(Winter 1987-88)
PHASE Ill
F ARFIELD
ICE TRANSPORT
MODEL
( 1988)
~
~
Equation ,____
Formulation
Reassessment
of Baseline ~
Data
Requirement a
Equation ____..,
Formulation
Figure 8-1.
Sensitivity Near field Are Monitor
Additional Studies No
1----o~ ~
Analysis Ice Model ~ Project
Operations
s
Input Data Mitigation -
Formatting Planning
Baseline Are Monlt or
Data Nearfield Additional Studies No r--
Collection Ice Model ~ PrQject
Operations
s
Mitigation
Planning
Sensitivity Farlleld Are Monlt or
r--Additional Studies No
Analysis Ice Model Required Project
? Operations
Yes
Mitigation
Planning
Approach to Additional Studies
CP
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.,.,.
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SECTION 9.0
BIBLIOGRAPHY
9.0 BIBLIOGRAPHY
Alaska Power Authority, No date. Application for License for major
unconstructed project, Bradley Lake Hydroelectric Project.
F.E.R.C. Project No. P-8221-000, Volume 1, Initial Statement,
Exhibit A, B, C, D, F and G.
Arctec Alaska, Inc., 1985. Analysis of wind, waves and sedimentation
for the Bradley Lake barge basin and access channel. Prepared for
R&M Consultants, Inc.
Arctic Environmental Information and Data Center, 1986. Alaska climate
summaries. Alaska . Climate Technical Note No. 3, University of
Alaska -Fairbanks, Anchorage, AK.
Arctic Environmental Information and Data Center, 1986.
data sheets: Climatological listing for period
University of Alaska, Anchorage, AK.
Miscellaneous
1932 -1984.
Bradford, J.D. and S.M. Smirle, 1970. Bibliography on northern sea ice
and related subjects. Canada Ministry of Transportation and Dept.
of Energy, Mines and Resources, 188 p.
Burbank, D.C., 1977. Circulation studies in Kachemak Bay and lower
Cook Inlet. Alaska Department of Fish & Game, 207 p.
Carstens, T., 1971. Prevention of ice formation by forced m1x1ng.
Proc. Int. Conf. of Port and Ocean Engr. under Arctic Conditions,
Vol I., pp. 140-151.
Carstens, T. and H. Rye, 1981. Controlling impact of changes in fjord
hydrology. In Freeland, H. J. , D. M. Farmer, and C. D. Levings
(eds), Conf. on Fjord Oceanography, Victoria, Canada, Vol. 4, pp.
341-346.
Cold Regions Research and Engineering Laboratory {CRREL), 1979. CRREL
technical publications. U.S. Army, Corps of Engineers, CRREL, 702
p.
Colonel!, J.M., 1980. Circulation and dispersion of Bradley River
water in upper Kachemak Bay. Prepared by Woodward-Clyde
Consultants for the U.S. Army, Corps of Engineers, 51 p.
Foulds, D.M., 1981. Peaking hydro generating stations in winter. IAHR
Int'l. Symposium on Ice, Quebec, Vol li., p. 152-159.
Gatto, L.W., 1981. Ice distribution and winter surface circulation
patterns, Kachemak Bay, Alaska. U.S. Army, CRREL Report 81-22.
Go sink, J.P. , 1984. Length of the open-water reach below a dam or
reservoir. Prepared for the Alaska Dept. of Commerce and Economic
Development. Univ. of Alaska, Geophysical Institute, 62 p.
1-1544-JW 9-1
Gosink, J.P. and T.E. Ostercamp, 1981. A theoretical investigation of
the potential modification of ice formation in Kachemak Bay by the
Bradley Lake Hydroelectric Power Project. Prepared for the U.S.
Army, CRREL.
Gotlib, Ya.L., M.W. Gorina, A.I. Khoudyakow, and S.N. Nazarenko-
Sokolovskaja, 1983. Change of river ice regime in relation to
construction of hydroelectric plants under severe climatic
conditions. XX Congress of Int '1. Assoc. for Hydraulic Research,
Moscow, Vol. II, pp. 149-154.
Haynes, F.D., G.D. Ashton, and P.R. Johnson, 1981. Performance of a
point source bubbler under thick ice. IAHR Int'l. Symposium on
Ice., Quebec, Vol. 1, pp. 111-121.
Hutcheon, R.J., 1972. Forecasting ice in Cook Inlet, Alaska. NOAA
Technical Memorandum AR5, U.S. Dept. of Commerce, National
Oceanographic and Atmospheric Admin. , National Weather Service,
Alaska Region, Anchorage, 14 pp.
Karnovich, V.N., I.N. Shatalina and I.N. Sokolov, 1983. Winter
operation of pumped storage power plant basins and canals. XX
Congress of Int'l. Assoc. for Hydraulic Res., Moscow, Vol II, pp.
173-180.
Korzhhavin, K.N., 1983. The effect of hydroconstruction on the ice
regime of some Siberian rivers. XX Congress Int'l. Assoc. for
Hydraulic Res., Moscow, Vol. II, pp. 155-158.
Knull, J.R., 1975. Oceanography of Kachemak Bay, Alaska. A summary of
1969 studies, manuscript reports, file no. 113, NMBS-NW Fisheries
Conference, Nuka Bay, Alaska.
LaBelle, J.C., J.L. Wise, R.P. Voelker, R.H. Schulze and G.M. Wohl,
1983. Alaska marine ice atlas. Arctic Environmental Information
and Data Center, University of Alaska, Anchorage, AK, 302 pp.
Marcotte, N., 1981. Regime thermique et regime des glaces en riveiere
etude de cas. IAHR Int'l. Symposium on Ice, Quebec, Vol 1., pp
412-422 (in French).
Martin, S. and P. Kauffman, 1980. 1 A field and laboratory study of
wave damping by grease ice. Submitted to Journ. of Glaciology.
National Climate Center, 1977. Local climatological data, 1976, Homer,
Alaska. U.S. Dept. of Commerce.
National Climate Center, 1986. Local climatological data, 1985, Homer,
Alaska. U.S. Department of Commerce.
Ott Water Engineers, Inc., Alex Horne Assoc., and J.W. Buell, 11981.
Bradley Lake water quality report. Preparted for the U.S. Army
Corps of Engineers.
1-1544-JW 9-2
Pekovitch, A.I. and I.N. Chatalina, 1970. Control of frazil ice
formation downstream from power plants situated in river mouths.
IAHR Ice Symposium, Rykjavik, Iceland, Paper No. 4.2 1 4 p.
Pruden, F.W., R.L. Wardlaw, D.C. Baxter and J.L. Orr, 1954. A study of
wintertime heat losses from a water surface and of heat
conservation and heat addition to combat ice formation in the St.
Lawrence River. National Research Council of Canada, Report No.
MD-42.
R&M Consultants, Inc. , 1985. Barge access alternatives, Bradley Lake
Hydroelectric Project. Prepared for Alaska Power Authority and
Stone & Webster Engineering Corporation.
R&M Consultants, Inc., 1985. Bradley Lake Hydroelectric Project, Phase
I -Hydrology report, review and analysis of historic wind data.
Prepared for the Alaska Power Authority and Stone & Webster
Engineering Corporation.
Saegrov, S., 1978. Prevention of freezing in fjords. In Proc.
Sixteenth Coastal Engineering Conference, Hamburg, Vol. III, pp.
2958-2977.
Skladnev, M.F. and V.E. Lyapin, 1983. Ice engineering investigations
in the USSR -Present state of the art. XX Congress of Int 1 1.
Assoc. for Hydraulic Res., Moscow, Vol. II, P. 132-139.
Slaughter, C.W.,
literature.
1969. Snow albedo modification, a
U.S. Army CRREL, Tech. Report 217, 25 p.
review of
Stone & Webster Engineering Corporation, 1987. Bradley River Water
Quality Report 1986. Prepared for the Alaska Power Authority.
U.S. Army Corps of Engineers, 1982. Environmental impact statement,
Bradley Lake Hydroelectric Project, Alaska. Appendixes.
U.S. Coast & Geodetic Survey,
Seldovia Bay, Cook Inlet.
1968. Tidal bench marks,
U.S. Dept. of Commerce, 3 p.
Seldovia,
U.S. Coast & Geodetic Survey, 1951a. Tidal bench marks, Halibut Cove,
Kachemak Bay, Cook Inlet. U.S. Dept. of Commerce, 1 p.
U.S. Coast & Geodetic Survey, 1951b. Tidal bench marks, Bear Cove,
Kachemak Bay, Cook Inlet. U.S. Dept. of Commerce, 1 p.
U.S. Coast & Geodetic Survey, 1967. Tidal bench marks, Homer, Cook
Inlet. U.S. Dept. of Commerce, 2 p.
Votruba, L. and V. Matousek, 1970. L'assurance de !'alimentation
ininterrumpue par 1' amenee 1 d' eau ouverte en hiber. IAHR Ice
Symposium, Reykajvik, Iceland, Paper No. 2.7, p. 8 p.
1-1544-JW 9-3
Woodward-Clyde Consultants, Entrix, Inc., and Stone & Webster
Engineering Corporation, 1985. 1985 Bradley river water quality
report. Prepared for the Bradley Lake Hydroelectric Project.
Zubov, N.N. 1943.
oceanographic
492 p.
1-1544-JW
Arctic ice. Translated from Russian by the U.S. Navy
Office and the American Meteorological Society,
9-4
-
APPENDIX A
NOTES OF LOCAL
INTERVIEWS
12/11/86 PM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Joel Gay (235-7767)
Occupation: Homer Weekly News
Number of years living in Bomer:
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Time {Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe {Location, Type and Thickness)
weather Conditions {Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe {Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Reviewed copies of Homer News for period of Jan 1975 -June 1986
for photos and stories on ice in bay. Obtained following
Feb 6, 1975
Feb 26, 1976
Mar 31, 1977
Dec 15, 1977
Feb 22, 1979
Jan 22, 1981
Jan 14, 1982
Cover photo showing pan ice around George F. Ferris
Cover photo showing i~e in SBH
Cover Photo showing ice in Beluga Slough
Cover photo showing boats fighting ice off small
boat harbor. Story on fishing on Pg. 19
Photo on page 3 showing ice in SBH
Photo on page 3 showing ice in SBH
Photo on page 5 showing ice in SBH
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: John Bury
Occupation: Harbor Officer
Number of years living in Bomer: Since 1978 (6 yrs working in
harbor)
Do you own or operate a boat or airplane (if yes, describe)?
Boats 22', no winter
Have you seen ice in the harbor?
Numerous occasions
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Conditions for ice formation
-Usually get ice any time temp drops to 10-15°F or less, can
happen in a matt~r of days.
-When temps get to 0°F, blocks in harbor freeze together so you
can walk on it; hasn't happened for 3 yrs.
-With NE wind, ice accumulates in Mud Bay. Currents always go
south along inner spit, even on flood tide -ice bounces along
inner spit and eventually moves past spit to outer bay.
-Usually get ice in harbor with NE wind and flood tide. Harbor
can get l/2 full before entrance jams up.
-can take 1-2 months for harbor to clear out after freeze.
-Winters have been warmer for a number of years.
-Prevailing winds are NE in winter.
-Occas. get SW wind with low pressure moving through. This will
generally move ice out of inner bay.
-Harbor can freeze over with skim of ice (<1/2 -1") thick
Types of ice
-Pans -small pans typically 1-3' and round and 3-6" thick. Can
get to 20'. Sometimes get pans 100' across and are usually
rounded with jumbled edges (come in from Mud Bay and head of
Bay). Larger pieces may be refrozen smaller pieces.
-Shore ice -formed on beaches
Other
-Very common to have ice on Mud Bay, would be uncommon not to
have it.
-On occassions Russian boats from Kachemak Sea have got caught
up in ice and carried to Mud Bay.
-Harbor keeps daily logs -good data source; possible to pay
someone to,go through records.
-Specific events
About Nov 17, 1977 -piling in main dock damaged by ice.
Feb 23, 1984 -Dock piling damaged and ice between floats.
-Larger steel boats pretty much ignore ice -most bigger boats
don't fish locally. Smaller dungie and wood boats cannot get
out of harbor sometimes.
Fishing schedules
Tanner -Jan, Dec: deeper waters of inner and outer bay.
Dungie -Year round normally less in winter; both sides of bay
all the way up.
Shrimp -Some pot fishing in winter.
> a: ::l III
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12/12/86 AM -MEET
12/12/86 AM -TELE
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACHEMAK BAY ICE FORMATION STUDY
Name: Larry Smith (235-7879, 235-7199)
Occupation: Carpenter, some comm. fish., committee
Number of years living in Homer: Since 1968
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures}
Have you ever seen ice in other areas of the bay?
Time (Month, Year}
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe {Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Provided copy of late summer 1973 "The Spit."
-Arranged for meetings with Yule Kilcher, Bill Choate, and Mike
Sheppard in his office. Also arranged meeting with Garland
Blanchard.
-Provided names of number of persons to interview.
12/12/86
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Yule Kilcher (235-8713 or 235-7850; Box 353, Homer)
Occupation: Homesteader, politics
Number of years living in Bomer: 42 years in Homer; Traveled to
Bomer for 50 years.
Do you own or operate a boat or airplane (if yes, describe)?
Bave you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness)
weather Conditions (Winds, Temperatures)
Bave you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Bave you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Types of ice
Calls most ice formed by slush freezing to beach as drift ice.
Some may anchor to bottom higher up. Drift ice can get to 6 or
10 feet. Pieces which typically break off are 10-30' india
and 4-6' thick.
1/2 mile
anchored
Drift Ice
-Bradley Lake water will form drift ice.
Other
-Halibut and Bear Cove will freeze over occasionally. With more
freshwater, coves will freeze over with less cold weather.
-Earthquake of 1964 dropped inlet 4-5 feet allowing more warm
water into the inlet. This has resulted in a more maritime
climate.
-Normally get some drift ice each year. Harbor usually freezes
in.
-When you get cold temps and 2-3" of water on beach -will start
freezing.
-Weather at least 10° colder in winter at head of bay -
interested in salinity and temperature profiles at head of bay
to determine stratification.
-Bradley river has about 1/5 of total flow to head of bay.
-Worst winter was 1946/47. In early part of freeze, slush and
ice dammed up at Chugachik Island at a 23' tide level creating
a dam. Ice behind was at about 18' elevation. Yule rode his
horse across the bay to Bear Cove.
-Kilsher used the beaches extensively for travel during the
winters.
-No fishing when ice gets really bad.
-Wants contingency funding to compensate fishermen for demon-
stratable damages from ice from the project -e.g., for
clearing ice our of harbor or for damage to boats.
-Very critical of previous ice study.
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REVIEW OF
IC lNG STUDIES
12/12/86 AM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Mike Sheppard {235-7486~ Box 2229, Homer)
Occupation: Comm. Fish, Pottery
Number of years living in Bomer: Since 1971
Do you own or operate a boat or airplane (if yes, describe)?
Deck hand
Bave you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Bave you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Bave you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Tempetatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Need about 2 weeks of cold temps before ice becomes apparent.
Starts as brash or frazil ice lapping on the beach. May freeze
to flats above MHHW. Ice from flats aprobably accounts for
90-95% of ice in bay.
-Thinner clear freshwater ice is more dangerous for loosing gear
and causing damage. Thin ice forms with cold, clear, calm
weather. It can form very rapidly -1/2 to 1 inch. You can
see front move. Has heard of thin ice forming 5 times since
1971 and has personally seen it twice. Thin ice doesn't form
on the north side of the bay.
-Thinks the Bradley Project will be a big ice generator. Thinks
large freshwater in flow followed by a cold snap will cause a
major ice problem.
-Has problems with ice report; doesn't see how fresh water will
mix with sea water.
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12/12/86 AM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Bill Choate (235-3925~ Box 493, Homer)
Occupation: Comm. Fish., Diver
Number of years living in Bomer:
39 years
Do you own or operate a boat or airplane (if yes, describe)?
3 boats -salmon, halibut, and crab
Have you seen ice in the harbor?
Numerous times
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous times
Time {Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time {Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions {Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Conditions for ice formation
-Forms at head of bay and in Mud Bay, at Mud Bay ice builds more
than being formed.
-Normally forms when temps drop to 20°F or less and faster when
windy.
-Once Bay water gets down to 29°F, ice can form very rapidly.
-In all small bays on south side, fresh water accumulates and
freezes, winds and tides take it out.
-Big tides and strong winds normally move ice out.
Types of ice
Floes - 1 ft to 10 acres in size, usually stays within 1 mile
of shoreline near harbor.
-Freshwater ice -clean, forms in coves.
~ Brash ice -slush.
Other
Checks boat in harbor 2-3 times a week in winter.
-Bad years
1971-72 winter?
1972-73 winter?
Once broke a shaft in ice outside harbor and walked on ice to
shore -chunks 3-4' thick and somewhat frozen together.
-Previous study doesn't make sense with regards to mixing. Can
normally see plumes for some distance offshore. From diving
have seen a 6" thick freshwater lens 1/2 mile offshore.
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12/12/86 PM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Virgo and Fred Anderson (235-8725; Box 115, Homer)
Occupation: Comm. Fish. (Kristian)
Number of years living in Bomer: Since 1924
Do you own or operate a boat or airplane (if yes, describe)?
various boats, present Kristian -58'
Have you seen ice in the harbor?
Numerous occasions
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous occasions
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Conditions for ice formation
-varies greatly from year to year.
-Dependent on how much snow and cold weather with heavy snow,
get lots of slush ice.
Types of ice
-Slush ice -get with heavy snow -can almost cover entire inner
bay except deeper areas.
-Pans -up to 1 ft thick, snow weighs down pans, floods and
builds ice thickness. Ridges 4-5' can form.
-Anchor ice -usually comes in spring thaw in late March, can be
6-8' thick and 20-30' in dia.
Source of ice
-Head of bay.
-Flats along north side of inner Bay.
-Coal Bay.
Timing
-Can have ice for 2 months during period Jan thru March.
-Ice normally doesn't build up to harbor until after X-mas, have
most problems in Jan and Feb.
Other
-There was much more flow in most rivers 50 years ago, glaciers
have melted back quite a bit and some glaciers are completely
gone now.
-Haven't had really bad ice for past 10-15 years. It was really
cold in the 1920s.
-Not many problems navigating with steel hulled vessels such as
Kristian, wood boats can have real problems.
-Ice occurs in winter with NE winds and cold weather, especially
with snow on the flats.
-Have seen 6" sheet in harbor (late 60s?} -formed locally.
Snow got on top of ice, depressed it and flooded and formed
thicker.
-About 1940 -entire dock went out at spit.
-Virgo and Fred were in lower 48 building a boat during the
1946/47 severe winter.
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12/12/86 PM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Joel Moss (235-8735)
Occupation: Ex-mining engr., comm. fish.
Number of years living in Bomer: Peterson Bay '46-'67, Homer '67
to present
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Numerous times
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous times
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year}
Describe (Location, Type of Damage, costs}
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Most ice forms at head of bay.
-Beach ice comes in with wind and is in layers, can easily be
4-5' thick. Will stay quite long, especially in Mud Bay.
Westerly winds will disperse it offshore.
-In recent years ice problems have been less with warmer
winters. Fishermen are no longer use to operating/coping with
ice.
-Prior to mid 1970s, usually some sort of ice pr~blem by early
Nov. Ice worst by end of Feb and usually gone by April.
-Can get freshwater ice in Tutka Bay and Halibut Cove. Grows
best with cold, calm weather.
-Anchor ice forms on beaches. When it comes off the beach on
high tides it moves down the north side of the bay. This ice
can be extremely thick and hard.
-Pan ice can be found in patches 1-2 acres or more and consists
of chunks other ice, also some small smooth stretches. Most
comes from head of the bay. Pan ice can get up to 2 or 3 feet
thick and probably mostly form beach ice (refrozen pieces).
Not sure if this is fresh or salt water ice.
-Ice can form in salt water with low tides and cold weather.
-Can get slush ice in open water 6" thick (est).
-Worst ice in early March of 1956 (at least at Peterson Bay).
Shut everything down for awhile.
-Wife kept daily diary of max/min temps and general conditions.
Ice was fairly normal occurrence so not always mentioned.
-Has a number of photos which were reviewed:
Jan '69 -Extensive ice in harbor,
Mid -late Jan '71? Harbor completely frozen in and could walk
anywhere; worst Joel had seen; ice est at 1 ft thick with 2-3'
drifts on top. Can obtain photo on request,
March 28, 1964 Photo of harbor after EQ; pieces of beach ice
seen.
-Joel indicates there is noticeably less ice in glaciers.
-Common to get ice in harbor now and doesn't believe added
water from Bradley will cause problems.
-Others to see: Yule Kilcher -homesteader.
Steve Zawistowski -trapper at head of bay.
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12/13/86 BKFT
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACHEMAK BAY ICE FORMATION STUDY
Name: Garland Blanchard (235-7917)
Occupation: Cornm. Fish. (Dungie/Tanner)
Number of years living in Homer: 6 years
Do you own or operate a boat or airplane (if yes, describe)?
Steel boat
Have you seen ice in the harbor?
Numerous times
Time (Month, Year)
Description (Location, Type and Thickness)
weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous times
Time (Month, Year)
Describe (Location, Type and Thickness)
weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Ice formation
-Ice forms at head of bay with 25 mph winds and 20°F temps.
Prevailing direction is NNE
-When temps drop to 0°F you can have major ice problems
-Skim of ice first
Village by Nov 1.
early Nov -March
6 years.
forms on marshlands up bay from Russiana
This ice is usually frozen solid during
or early April. Has occurred for 5 of past
-Thicker pancake ice normally forms between Russian Village and
Chugachik Is. throughout winter. Pancake ice is slough-off
from skim ice area. Size of pancake ice: 5-50 ft dia,
6" to 3' thick.
-Most ice in bay is generated in pancake ice area between
Russian Village and Chugachik Is.
Head of Bay
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Types of ice
Russian
Village
Freshwater ice -harder; takes longer to melt
Saltwater ice -softer; melts quicker
Ice
Pancake ice -looks like pancakes when it breaks up
Other
Chugachik
Is.
-Common to have ice during Nov -March/Apr uncommon not to have
ice in harbor at times between Dec and Mar.
-Rule of thumb by locals -if you don't get ice in the harbor by
Dec 15, its going to be a non-ice year (skim of ice in entire
harbor).
-Wood boats normally have to wait to get out of harbor when ice
is present. On ebb, ice moves against spit. On flood, ice is
pushed back up bay and spreads out a bit allowing wook boats to
get through.
-During spring, warm weather and sunshine trigger breakup at
head of bay (Froze solid area). this ice normally all moves
out over a very short period -say 2-3 weeks -but sometimes
it takes 1-1 1/2 months. This usually occurs around April.
-Normal for ice to move along north shore, around spit and out
of inner bay with NNE wind.
-With 30 MPH WSW wind it will spread out over the entire bay.
-Saw ice completely packed in from tip of spit to McNeil Canyon
twice in past 6 years (Jan 1981? and Jan 1983?).
-Heard of ice further out in 1961? from Bill Bartillio.
-Garland normally fishes dungies from May -Dec fishes from
inside Chugachik Is. and aloang north side of inner bay to
spit.
-Fishes Tanners in Jan -Feb near Chugachik Is.
-Biggest concern is if a problem develops-how could it be
mitigated -could you stop or reduce flow.
-Get high currents around Chugachik Island at early flood
tide, up to 6-8 kts on large tide.
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12/13/86 AM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACHEMAK BAY ICE FORMATION STUDY
Name: Steve Zawistowski (235-6539, Mile 18, East Bay Rd)
Occupation: Fox farmer, Trapper, Comm. Fish, mail boat contract
1946-50
Number of years living in Homer: Since 1930 in various areas
incl Martin R. (1930-33), Bear Cove ( 1930-44), Seldovia, Homer
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Numerous times
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous times
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Ice formation
-Usually with NE winds and cold temps.
-Flats freeze up first, 2-3" and more with snow and higher
tides.
-Big tides move ice around.
Types of ice
-Drift ice -includes pan ice and slush, probably mixture of
freshwater and saltwater ice.
-Freshwater ice -forms at head of bay and is generally thin.
-Shore ice -dirty, mix of fresh and salt water.
Other
-Bear Cove normally gets ice for about 1 month -normally Feb.
Ice only at head of bay most years and usually 1 inch or less
thick.
-About 6 or 8 yrs ago the Russian boats froze in and later
lifted off with the big tides and floated back and forth in the
bay for some time.
-Extreme ice in Feb 1947. Froze solid above spit and held for 2
weeks. Main ice floes were 3 1/2 -4' thick. During this
period they had sunshine and 22 days where temp didn't get
above 0°F. Ice finally broke up with warm weather and big
tides. When it finally went it took out the city dock.
-According to old timers, the bay froze up completely in 1919.
-Other bad years -1932, 1943.
-Last 5-6 years haven't been cold and not much ice.
-Has only seen 3 winters when no real ice at all; last winter
was almost like that; 1925/26 winter -rivers didn't freeze per
old timers.
-Doesn't have any recollection/association of ice forming after
large freshwater inflows in winter.
-Dock history
First dock -Coal loading dock -destroyed by fire
2nd dock -Built in mid 30s -took out in 1947
3rd dock -some damage
-Many of the big glaciers have receded severed miles or so.
-including Sheep Ck Glacier. Not much left of Fox River Glacier
any more.
-Icebergs are carried into the harbor because you have a large
harbor and real small entrance -this causes strong currents at
the mouth which suck in ice from outside.
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REVIEW OF
ICING STUDIES
12/13/86 PM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Homer Museum
Occupation:
Number of years living in Bomer:
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
Museum has only one photo of ice in bay. Taken by Bill Wakeland
in 1947 from McNeil Canyon. Bill is now in Anchorage and he has
negatives. Museum ID# 827715.
Janet Klein works in museum M-T-W, Bam to Spm and is in Anchorage
this weekend
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12/13/86 via telephone
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Bob Herring (235-8029)
Occupation: Ship Pilot
Number of years living in Bomer: Since 1971
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Numerous times
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous times
Time {Month, Year)
Describe {Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
~
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe {Location, Type of Damage, Costs)
Weather Conditions {Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
General types
-Drift ice comes down from head of bay, pans 5-20' in diameter
plus brash.
-Sea ice forms in Mud Bay when you get 0°F weather for a few
weeks, it is laminated by successive freezing by successive
tides.
-Sea ice also forms in the small boat harbor with 0°F temp. Can
grow to 1 ft thick.
Other
-Generally get some ice in the harbor every year.
-Past 6-10 years have been fairly mild and have been able to
cope with ice in pilot boat.
-It was much colder in the early 1970s. During 1971-76 had bad
ice in harbor every year and could have problems getting in and
out of harbor for about a 2 week period. He recalled loosing
the rudder once and having prop damage several other times.
-Ice moves aqloang spit with N wind and into the small boat
harbor. If you get a lot of cold weather, the ice can weld
together.
-Worst ice he has seen was ice within 1 mile of spit, 100%
coverage.
12/13/86 PM Telephone
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACHEMAK BAY ICE FORMATION STUDY
Name: Clem Tillion (296-2207, Halibut Cove)
Occupation: Boat operator, etc
Number of years living in Bomer: 39 yrs
Do you own or operate a boat or airplane (if yes, describe)?
Yes
Have you seen ice in the harbor?
Numerous occasions
Time {Month, Year)
Description {Location, Type and Thickness)
Weather Conditions {Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Numerous occasions
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Feshwater pans form from snow, rain and runoff
-Bad ice areas: Mud Bay, Bear Cove, and head of bay. Bear Cove
and head of bay get much colder temps than rest of bay -comes
in from interior.
-Brash ice forms at head of bay -most ice form head of bay
accumulates in Mud Bay.
Need a number of factors to get a really bad ice year -low
tidal range, calm winds and cold weather for sustained period
of time.
-Ice i~ Mud Bay gets 1-2 ft thick and can stack 2-3 high during
cold weather.
-Normally boats can have proablems getting in and out of harbor
1-3 weeks each winter.
-Bad years
1946/47 -Froze over from Gull Is to spit
1956 -Froze over Bear Cove to Homer -Took out city dock, see
Larry Farnen.
1973 -Took 2 hrs to get boats out of harbor using pilot boat
During bad years, freshwater effects can be north of a slightly
curved line between tip of spit and mouth of Fritz Creek
-Past 10 years have been mild, El Nino has resulted in warmer
ocean waters along coast: would need 2-3 severe winters to get
water temps back down.
-Thermocline 2-5 fathoms down depending on winds and waves.
Below thermocline temps range from near 50°F in summer to high
30°Fs in winter.
Prevailing currents fro inner bay -in on south side and out on
north side -influence ice movement in winter.
12/13/86 PM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Jim Sink (235-7771)
Occupation: Helicopter Pilot
Number of years living in Bomer: 3 yrs
Do you own or operate a boat or airplane (if yes, describe)?
Helicopter
save you seen ice in the harbor?
Every winter
Time (Month, Year}
Description (Location, Type and Thickness}
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Every winter
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or floa~ plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Normally get patches of ice in boat harbor every year. One
year (1984?) heard people were walking on it.
-Ice usually worst in February.
-Ice normally first appears around freshwater sources
{intertidal channels). Has seen some of this shore ice 2'
thick.
Most ice is right along shoreline, particularly around river
mouths. Has seen occasional ice throughout northern half of
inner bay with some isolated floes up to 1/2 mile across. Has
only seen up to 1/10 coverage max in this area.
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REVIEW OF
IC lNG STUDIES
12/14/86 AM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: Louie Strutz (234-6211)
Occupation: Boat yard in Mud Bay
Number of years living in Bomer: Since 1954
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs)
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Has a workshop right on bluff at Mud Bay
-Ice is really different from year to year. Can get ice 3 or 4
times per year as early as November. Sometimes there hasn't
been ice till Jan. Last 9-10 years have been light years.
-Ice first forms at the head of Mud Bay
-Some sheet ice forms locally (6-7", if you have a cold period
for 2 weeks it can form real fast.
-Chunk ice comes in from elsewhere. This ice is big enough to
haul in boulders as big as a table -he has actually seen this
happen. Chunk ice can get 3-4' thick with pans up to 50'
across.
-Ice forms on the shore and can get up to 3' thick.
Haven't seen shore ice to speak of for 9 or 10 years.
-With a couple of cold days, lots of slush ice can be seen
at the head of Mud Bay.
-Harbor used to get ice any time in the winter with cold
snap. Sometimes get 4-5" ice in the harbor and can walk
from boat to boat. In these cases, smaller boats wait
till the big ones leave, then follow them out.
-Snow on the ground has been about 1/4 of what it used to
be. It's really warmed up in Homer.
-Boat damage from ice has been fairly minimal.
Thick
Shore Ice
..---full of cracks
-Tides can move ice in fairly but it usually takes longer
to move it out. NE winds bring ice in and SW winds move
it out.
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12/14/86 AM
REPRESENTATIVE LIST OF QUESTIONS FOR LOCAL RESIDENTS
KACBEMAK BAY ICE FORMATION STUDY
Name: John Cunningham
Occupation: Lives on bluff 1/2 mile NW of spit
Number of years living in Bomer: Since 1970
Do you own or operate a boat or airplane (if yes, describe)?
Have you seen ice in the harbor?
Time (Month, Year)
Description (Location, Type and Thickness}
Weather Conditions (Winds, Temperatures)
Have you ever seen ice in other areas of the bay?
Time (Month, Year)
Describe (Location, Type and Thickness)
Weather Conditions (Winds, Temperatures)
Have you ever had boat, gear or float plane damage from ice?
Time (Month, Year)
Describe (Location, Type of Damage, Costs}
Weather Conditions (Winds, Temperatures)
Other Comments?
Extreme Ice Conditions
Types of Ice
Normal and Extreme Winter Oceanographic Conditions
Normal and Extreme Winter Hydrologic Conditions
-Casual comments during interview with Louie Strutz.
-1970-75 were bitter cold winters. Berms of ice formed on the
beaches. It's been much warmer during the last 10 years.
-Have seen pans go by when temps drop to 0°F.
-Has never seen the bay completely iced over.
APPENDIX B
REVIEW COMMENTS
APPENDIX B
REVIEW COMMENTS
Review comments for the interim report for the Review of Icing
Studies dated March 5, 1987 were requested from the following
individuals and/or groups:
1. Residents of Homer, Alaska
2. D.C. Burbank -Alaska Department of Fish and Game
3. J.M. Colonell-Entrix, Inc.
4. L.W. Gatto -Cold Regions Research and Engineering Laboratory
5. J.P. Gosink and T.E. Ostercamp-University of Alaska, Fairbanks
6. S.F. Daly -Cold Regions Research and Engineering Laboratory
This appendix provides copies of written comments received as well
as responses to those comments.
DEPARTMENT OF THE ARMY
COLO REGIONS RESEARCH AND ENGINEERING LABORATORY, CORPS OF ENGINEERS
HANOVER, NEW HAMPSHIRE 03755-1290
Geological Sciences Branch
Mr. David R. Eberle
Project Manager
Alaska Power Authority
P.O. Box 190869
Anchorage, AK 99519-0869
Dear Mr. Eberle:
31 March 1987
Thanks for the opportunity to review the Interim Report. I've
attached my comments and included two reports Mr. Britch may find useful.
I'd like to get a copy of the final report when it becomes
available.
Encls.
Sincerely,
Lawrence W. Gatto
Geologist
Geological Sciences Branch
•·
Interim·Report, "Review of Icing Studies,
Bradley Lake Hydroelectric Project,"
by
Robert P. Britch
Northern Technical Services, Inc.
Comments by
Lawrence W. Gatto
USACRREL
(31 March 1987)
l. p. 2-6: The last sentence is incomplete. Something is missing
on the bottom of p. 2-6 or the top of p. 2-7.
2. Table 2-6 should have units, cfs, shown somewhere.
3. p. 3-l: I am skeptical about the accuracy of the information obtained
in response to questions #1, 2 and 6. Someone's recollection of
past events and conditions can be very poor and inaccurate.
4. p. 3-1: lt3 should say ". . . where ice occurs "
5. p. 3-2 to 3-4: Much of the percentages, thicknesses and other
information given on dominant ice types are just guesses.
6. p. 3-7: Disagreement on specifics is common when based on memory,
i.e. two versions of ice extent during 1946-1947 from Zawistowski
and Kilcher.
7. Section 4.3: Tides and currents are probably not much different
on average from winter to winter. Real controlling factor is air
temperature with minor effects from winds, snow and inflows.
8. Figures 4-1 and 4-2 do not agree with Tables 2-2 and 2-3,
respectively. For example, in 1947, there were 22 days when the
average daily air temperature fell below 0°F, not one day as shown
in Figure 4-2; 1946 had 14 days not 35. Very confusing.
9. Comments in Section 5.4 regarding my report were fair and true.
On reading this Interim Report, I found it satisfying that my
satellite imagery observations, however limited, agree with general
ground observations on ice distribution and movement.
10. I don't see how section 6.3.2 and the Vangen Power Station section
(p. 6-5) contribute to the topic of this report. Why include
them?
11. p. 6-ll: Shouldn't footnote read, "Complete citations provided
in Section 9.0, Bibliography"?
12. p. 8-7, Section 8.3.4.2, first line: "Measurements ... "
RESPONSE TO L. GATTO COMMENTS
1. Part of the sentence was omitted from the draft. This has
been corrected.
2. A footnote has been added to reflect the units.
3. Many of the persons interview~d appeared to have an excellent
recollection of past events and several had logs or diaries
they referred to. overall, we feel that we had a very
consistent story from most persons.
4. The sentence has been modified.
5. While some discrepancies were noted in specific numbers, we
feel that the local observations do provide an approximate
range of values to be expected. Based on our experience
elsewhere in Cook Inlet, none of the numbers appeared to be
totally out of line.
6. Discrepancies between these two individuals is probably a
result of the timing and extent of observations. Overall, we
can probably conclude that the event was likely extreme.
7. The intent of this section was to indicate that ice
conditions can be different if they are going through a low
range or a high range.
8. These inconsistencies have been corrected.
9. Comment noted.
10. All information obtained, regardless of its specific
relevance to the project, was included in the report.
11. This has been corrected in the final report.
12. This has been corrected in the final report.
Mr. David R. Eberle
Project r·1anager
Alaska Power Authority
P.O. Box 190869
701 East Tudor Road
Anchorage, AK 99519-0809
Dear ~1r. Eberle:
April 1, 1987
Re: Review of Icing Studies-Interim Report
Bradley Lake Hydroelectric Project
\~e would like to make a few brief comments regarding the above review
document, referring particularly to pages 5-4 and 5-S. A detailed reevalu-
ation would require assessment of data obtained since the report was
comp 1 e ted.
1) He disagree with the statement that ice production on the beach is I
the predominant mechanism for production of ice in the inner bay. This
form of ice production is much more visible and is therefore easily 1
observed by local residents. However, the much larger water surface area
and expected fresh water lens area offer considerably greater exposure
for surface heat loss.
2) It is unclear whether the Corps of Engineers (COE, 1982) study of
vertical temperature profiles in Bradley Lake is the same study which we
cited in our report (see figures 6, 7, 8 and 9). If it is, note that
water temperatures at the 50 ft. depth nearer the tailrace (stations 13
and 14) are considerably warmer than temperatures further away (station
12), typically about 3°C. We have included a table of temperature oro-
files from several glacial lakes in Southcentral Alaska. Note that at
the 50 ft. (15 m) depth the temperature is typically about 2°C.
Our ca 1 cula ti ons for "net ice production due to entering fresh water" 2
were based on the assumption that the discharge would be taken from near
the lake bottom, and therefore a temperature of 4 oc was used in our
calculations on page 27. This temperature produced a net ice production
decrease. Note, however, that on page 28 we a 1 so ca 1 cul a ted the net ice
production for a lake intake temperature of 2°C; this predicted that
net ice production would be a factor of 10 less than present production.
However, the calculations are indeed sensitive to the assumed lake intake
temperature; when the lake intake temperature is assumed to be 1oC the
net ice production increases to 4.7 • 10 10 g/day or a factor of 2.5
higher than at present.
Geophysical Institute, University ot Alaska
Fairbanks, Alaska 99775-0800
PHONE: 907-474-7558 T&LEX: 35414 GEOPH INST FSK
FAX: 907-4 74-7290 TELEMAIL: GEOPH.INST.FSK
Mr. David R. Eberle
Page Two
April 1, 1987
Temperature at depth in a lake are difficult to predict. We refer you to
the publication, Northern Lake Modeling, J. P. Gosink, Cold Regions
Science and Technology, in press. The article should be available within
one or two months, or if you prefer, we could send you a xerox copy of
the draft.
We most certainly recommend that the tailrace intake be located as
deep as possible in the lake to obtain maximum water temperature through
the ta i1 race. ·
l 4
3) We agree with the conclusion on page 7-7 that the rate of mixing of 1
the seawater and freshwater has a large effect on the potential for and
timing of ice production, such that increased mixing decreases ice 5
production. This was also stated in our conclusions (page 32), and the
effect is quantified in terms of the fresh water lens area, AL.
4) The control volume specified on page 14-15 is the entire bay, from I 6
Homer Spit to the beaches at the head of the bay.
5) Our analysis of the lens area was a conservative (large) estimate.
The proportionality between Froude number and fresh water lens area (page
44) is most appropriate for a quiescent basin. If additional mixing is
introduced by tidal fluctuations, we would expect that the fresh water
lens area would decrease, and consequently, that the net ice production
rate would decrease. Similarly, the use of bubble systems to mix fresh
and salt water, as recommended by Carstens, would decrease net ice
production.
If further questions and additional reanalysis is required, it may be
necessary to formulate an agreement of work. Please let us know the
extent of reevaluation required.
Sincerely,
..:_~ ·f/ :// ':V
. 1 . /_---:1-C""'"""'.J-::;..
•J
J. P. Gosink
Associate Professor of Geophysics
;r:P~
T. E. Osterkamp
Professor of Physics and Geophysics
JPG/sgf
Deeth (m)
0.0
0.5
1 .0
1 .5
2.0
2.5
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
12.0
13.0
14.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
. 26.0
27.0
27.5
28.0
29.0
30.0
31.0
32.0
33.0
34.0
35.0
36.0
37.0
38.0
~0.0
42.0
44.0
48.0
50.0
52.0
56.0
60.0
TEMPERATURE PROFILES ON APRIL 16, 1982
SELECTED GLACIAL LAKES -SOUTHCENTRAL ALASKA
:,.. ·.
-. ·,
Kenai L. Skilak L. Tustamena L. -Eklutna
1. 4
2.0
2.1
2.1 .
2.2
2.0
2.1
2.0
2.0
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.8
2.8
3.0
3.3
3.3
3.4
3.5
3.6
3.6
3.7
3.7
3.7
3.7
3.7
3.7
3.7
3.7
3.6
0.8
2.3
2.8
2.9
2.9
2.9
2.9
2.9
2.9
2.9
2.9
2.9
2.9
2.9
3.0
3.0
3.0
3.1
3.3
3.4
3.6
3.6
3.6
3.6
3.5
3.4
3.5
3.5
'
0.9 (@ 0.2 m) 1. 0 .• 1.6
2.0 2. 6.
.. 3.3
2.0 3.4 .. 3.5
2.0 3.5
1.9 3.5
1. 9 3.6
1. 9 3.6
1. 9 3.6
1.9 3.6
1. 9 3.6
1. 9 3.6
2.0 3.6
3.6
1.9
2.0
L.
RESPONSE TO COMMENTS BY J. GOSINK AND T. OSTERCAMP
1. The presence of a cold intertidal area will in effect provide
another surface for heat loss to occur: and when considering
local effects at the head of the inner bay, this can be a
significant factor which needs to be evaluated. When
considering the entire inner bay; however, this effect is
perhaps less important, particularly during periods of
extreme cold weather.
2. The temperature data indicated in your report appears to be
inc om p 1 e t e • 0 t t W ate r ( 1 9 8 1 ) p r o v ides prof i 1 e s which
indicate that near freezing ( 2° C or less) lake water
temperatures can occur throughout Bradley Lake. In order to
be conservative, the coldest water temperatures should be
assumed.
3. We would appreciate receiving a copy of this report when it
is finalized.
4. We agree.
5. Comment noted.
6. As a theoretical analysis, it would be of interest to use a
control volume which includes the entire inner bay. However,
based on information obtained during interviews with local
residents, we expect that oceanographic and meteorological
conditions at the head of the inner bay are somewhat
different than those which occur as an average over the
entire inner bay. As such, we feel that it is also important
to consider a control volume which includes only the head of
the inner bay.
7. While we feel that your analysis was conservative in some
respects, it is our opinion that the effects of heat losses
to the intertidal area represent a very significant factor
which must be considered in an analysis which considers a
much smaller control volume which includes only the head of
the inner bay.
8. The merits of using a bubbler system should be assessed once
the near-field (head of the bay) effects are known.
-'........., -· i ... ~ u Lt U ~ ' i J ' ;:;
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STEVE COK'f'flt GOVERNOR
DEPARTl+IENT OF FISH AND GA1+1E
April 16, 1987
Mr. David R. Eberle
Project Manager
Alaska Power Authority
P.O. Box 190869
Anchorage, Alaska 99519-0869
Dear Hr. Eberle:
333 RASPBERRY ROAD
ANCHORAGE, ALASKA 99518·1599
PHONE: (907) 344.0541
Subject: Review of Icing Studies -Interim Report
Bradley Lake Hydroelectric Project
Thank you for the opportunity to review the Bradley Lake
Hydroelectric Project icing report. David Burbank, who did
the circulation studies in Kachemak Bay for the Department
of Fish and Game_ is sailing somewhere in the South Pacific
and was not immediately available to review the
aforementioned report. I will forward it to him in hopes
that he will receive it and respond, because he does have a
great deal of knowledge about oceanographic. processes in
Kachemak Bay.
Sincerely,
~a sky
Regional Supervisor
Region IV
Habitat Division
environmental and engineering excellence
ANCHORAGE, ALASKA
NEWBURY PARK, CALIFORNIA
FORT COLLINS, COLORADO
WASHINGTON, D.C.
LOMBARD, ILLINOIS
CONCOR~MASSACHUSETTS
PITISBURGH, PENNSYLVANIA
DALLAS, TEXAS
HOUSTON, TEXAS
SEATILE, WASHINGTON
NORTEC
A DIVISION OF ERT
(907) 276-4302
(805) 499-1922
(303) 493-8878
(202) 463-6378
(312) 620-5900
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