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EFFECT OF GLACIER ABLATION
UN THE SNETTISHAM HYDROELECTRIC PROJECT
LONG LAKE AND CRATER LAKE BASINS, ALASKA
with a section on STREAMFLOW RECORDS
. Prepared in cooperation with the U.S. ARMY CORPS OF ENGINEERS , ALASKA DlSTRICI'
UNITED STATES
DEPARTMENT OF THE INTFRIOF
GEOLOGICAL SURVEY
EFFECT OF GLACIER ABLATION ON THE SNETTISHAM HYDROELECTRIC PROJECT,
LONG LAKE AND CRATER LAKE BASINS, ALASKA
By Charles E. Sloan, Philip A. Emery, and Diana Fair
wHh a section on STREAMFLOW RECORDS
By Robert D. Lamke
Water-Resources Investigations Report 85-4315
Prepared in cooperation with the
U.S. ARMY CORPS OF ENGINEERS, ALASKA DISTRICT
Anchora~e. Alaska
1986
UNITED STATES DEPARTMENT OF THE INTERIOR
DONALD PAUL HODEL, Secretary
GEOLOGICAL SURVEY
Dallas L. Peck, Director
For additional information
write to:
District Chief
U.S. Geological Survey
Water Resources Division
4230 University Drive, Suite 201
Anchorage, Alaska 99508-4664
ii
Copies of this report can be
purchased from:
Open-FiJe Services Section
Western Distribution Branch
Box 25425, Federal Center
Denver, Colorado 80225
Telephone (303) 236-7476
CONTENTS
Abstract .......................................................... .
Introduction ....................................................... .
Description and location of study area •.••.••...••..•••.•.•.•••
Purpose of the study ......•...•..••••.•....•..••..•...••. ; •••..
Study methods ...................................................... .
Glacier activity .................................................... .
Effects of glacier ablation on runoff .••..•..•••..•••.•••.••..••.••.
Streamflow records ................................................. .
Introduction .................................................. .
History ....................................................... .
Streamflow analysis ........................................... .
Results ....................................................... .
Conclusions ............................................................ .
References cited ................................................... .
Plate
Figure
ILLUSTRATIONS
I. Map showing areas of perennial snow and ice in
Crater Lake and Long Lake basins, Alaska
1. Map of location of the study area and gaging
Page
1
]
1
3
3
4
10
12
12
13
13
15
22
22
stations.............................................. 2
2-6.
2.
3.
Photographs of:
"New" lake neRr the upper end of Long Lake and its
tributary glaciers, August 23, 1984 ...•••••.•..•••....
"Sideways" glacier in tributary valley to Long River,
5
August 23, 1984....................................... 6
4. Valley glacier at head of Crater Creek, August 23,
1984 .•••....••.....•.......•........•...••.... " . It • • • • • 7
5. Snow conditions on "Bench" glacier tributary to
"New" lake, August, 23, 1984.......................... 8
6, Late summer snow line approximating extent of glacier
cover in Long Lake basin, August 23, 1984............. 9
TABLES
Table 1. Available aerial photography.............................. 3
2. Area in square miles measured on maps compilerl from
aerial photographs........................................ 10
3. Summary of streamflow data in the Daily Values File of
4-9.
4.
5.
6.
7.
8.
9.
WATSTORE. . • • . • • • • . . • • . . . . . . . • . • . • • . • • . . • • • . . • • . . . . . • . . . . . . 12
Data for gaging stations "near Juneau":
Sweetheart Creek (15030000) ••..•••.••••••.•••..•.....•..•
Long Lake Outlet (15032000) ......•••.•••.••...•...••...•.
Long River ( 1503<'!000) ...•..•.•.....••..••...•.........•..
Speel River (15036000) ••....•••..•••.•••..•.••••..•.•..•.
Crater Creek (15038000) ••..•.•..••...•...•.•..•..•.......
Dorothy Creek (15040000) ..•.•...•..•••.•...••..••..•.....
iii
16
17
18
19
20
21
CONVERSION TABLE
Hultiply to obtain
inch (in.) 25.40 millimeter (mm)
foot (ft) 0.3048 meter (m)
mile (mi) 1.609 kilometer (km)
square foot (ft 2 ) 0.09294 square meter (m2)
square mile (mi 2 ) 7..590 square kilometer (km 2 )
acre-foot (acre-ft) 1,7.33 cubic meter (m3)
cubic foot per second 0.02832 cubic meter per second
(ft 3 /s) (m 3 /s)
degree Fahrenheit (oF) °C=5/9 ( °F-32) degree Celsius (oC)
iv
EFFECT OF GLACIER ABLATION ON THE SNETTISHAM FYDROELECTRIC PROJECT,
LONG LAKE AND CRATER LAKE BASINS, ALASKA
By Charles E. Sloan, Philip A. Emery, and Diana Fair
ABSTRACT
Long Lake basin in the Snettisham Project Area southeast of Juneau, Alaska,
yields water used for the production of hydroelectric power. Development of
adjacent Crater Lake is planned to increase the Project's generating capacity.
Estimates of the hydroelectric potential of the lakes are basec on streamflow
records which are influenced by glaciers that cover 25 percent of the combined
basins. Analysis of strenmflow records shows that the quality and extent of
records in the area are sufficient to predict flow from the Crater Creek basin with
a fairly high degree of confidence. Comparison of aerial photographs indicates
that glacier ablation and recession have been continuous since at least 1929.
Estimates of ice-volume change from photogrammetric measurements indicate that less
than 2. 5 percent of the average runoff from the basins of Long and Crater Lakes ha.s
been from reduction in glacier-ice storage.
INTRODUCTION
Description and Location of Studv Area
Long Lake and Crater Lake basins (fig. 1) are located about 30 mi southeast of
Juneau, Alaska in the Tongass National Forest. Long Lake supplies water by means
of a lake tap through a tunnel to the Snettisham hydroelectric power plant. The
Corps of Engineers, Alaska District, pJans to construct an additional lake tap and
tunnel from Crater Lake in the near future to ado to the capacity of Snettisham in
order to meet the growing demand for electridty in the Juneau area.
Long Lake and Crater Lake occupy deep glacially scoured troughs surrounded by
steep glacier-clad mountains. The lakes are in the maritime zone characterized by
a wet, cool, and cloudy climate. The high div1des of their respective basins form
a barrier to storms from the North Pacific Ocean, providing an orographic effect
and causing unusually high precipitation. Aver;:~ge annual precipitation is about
140 in/yr at the SnetU sham power plant at sea 1 evel, and is estimated to be 230
in/yr in the Crater Lake drainage basin, only a mile away. Average monthly
temperatures range from 25 °F in January to 55 °F in July at Snettisham (U.S.
Department of Agriculture, 1979, map No. 30).
ALASKA
133030'
JUNEAU
EXPLANATION
A. Gaging station
Drainage basin boundary
Glacier
0 5 MILES
0 5 KILOMETERS
Figure 1.--Location of the study area and gaging stations.
-
Purpose of the Study
Design of the Snettlsham Project is based, in part, on estimates of water
yield from the drainage basins of Long and Crater Lakes. Owing to the absence of
adequate precipitation data in the area, these estimates of water yield are based
on gaging-station records for Crater Creek and Long River and by correlation with
other nearby gaging stations. An analysis of the streamflow records to verify
their accuracy and validity is described in a section of this report titled
Streamflow Records.
Glacier ablation in the basins of Long and Crater Lakes has provided a
previously unquantified component of the streamflow. Estimates of the contribution
to the flow of Crater Creek and Long River by ice-volume reduction from glacit~l
recession were required to see if this is a significant component. The purpose of
this study was to estimate the magnitude of this component of runoff from the area.
If ice melt is a large effect, then changes in long-term glacier dynamics aDd
balance would be important to basin yield.
This report presents an analysis of glacier activity in the basins of Long and
Crater Lakes and estimates of the contribution to stream£] mJ from change in ice
storage.
STUDY METHODS
The changes in ~lacier-ice vo~ ume within Long and Crater Lake has ins were
estimated by analyzing aerial photography (table 1).
Table 1.--Avai]<tble aerial photography
Type Approximate scale Date
Black and white trimetragon 1:19,000 Summer 1929
Black and white vertical 1:40,000 August 1948
Black and white vertical 1:16,000 July 1962
Black and white vertical 1:30,000 August 196l.
Color vertical 1:16,000 August 1977
Color infrared vertical 1:60,000 August 1979
Black and white vertical 1:120,000 August 1979
Color verU.cal 1:24,000 September 1984
Seasonal snow masked the boundaries of perennial snow and ice in some of the
aerial photography. This effect was most pronounced in 1964, when Crater Lake was
still ice covered at the time of the photography in August and there was extensive
J
seasonal snow cover throughout the basin. The masking effects of seasonal snow
cover were least in the tri.r:1etragon photography of 1929, the black and white
vertical photography of 1948, and the color photography of September 1984.
Areas of perennial snow and ice and basin boundaries were delineated on the
1948, 1979 color-infrared, and 1984 aerial photographs. A base map (plate I) for
compilation of the delineations was prepared by en] arging a portion of the Taku
River A-6 quadrangle from a scale of 1:63,360 to 1:31,680. Attempts to transfer
information from the photographs to the base map using a B.:msch and Lomb ZT-3 Zoom
Transfer Scope were unsuccessful because of the extreme distortion in the
photographs caused by the high vertical relief in the area. The photogrammetry
laboratory of the U.S. Geological Survey, Geologic Division, in Denver, Colorado
used a high resolution, PG-2 precision plotting instrument to do the necessary
plotting and measurements.
As an initial test of the methodology, delineated areas of snow and ice were
transferred from the 1948 and 1979 photography to the base map. Nine selected
glacier cross sections (plate I) also were measured on these photographs to
determine change in ice thickness. The method used was efficient and practical in
its application. A map of snow and ice was prepared from the September 1984
photography to show glad er conditions as they currently exist. Because> the 1984
photography haa less snow masking than the 1979 photography, the pedod 1948 to
1984 was selected to quantify the change :In ice volume. The snow and ice shown on
the 1929 trimetragon photography was also plotted in selected areas using a
stereoscope for comparison of snow and ice extent earlier in time.
A reconnaissance field trip of the aren Has made in August 1984 to field check
snow and ice conditions. Photofraphs of selected lers and glacial features
(f • 2-6) were taken on the ground and from a helicopter at the tjme.
GLACIER ACTIVITY
Accumulation to the valley glaciers in the Long and Crater Lake basins is
ma:Lnly by snow and ice avalanches clown the steep valley sides from the adjacent
r Glacier retreat is well exhibiterl at "New" lake (fig. 2), which was the
site of a large continuous glacier in 1929 (see plate I). In 1948 "New" lake was
about two-thirds occupied by a glacier that was cut off from its western tributary,
"Bench" glacier (fig. 5). "Sideways" glader (fig. 3) another example of glacier
activfty, is being supplled asymmetrically along its length by avalanches from the
valley side and its movement is controlled by melt along the north side of the
valley so that it is flowing at rjght angles to the axis of the valley.
("Sideways" and "Bench" glaciers, and "New" lake are informal names used in this
report to identify unnamed features.)
The termtnus of "Bench" glacier is jn about the same position in 1984 as it
was in 1948 because it rests at the brink of a very steep slope that causes
ice-fa]l avalanches to the lower valley. Snow and ice boundartes in the
accumulation areas alon~ the high ridges nlso have the same approx:Lmate positions
now as they have had since 1929 because the over-steepened valley walls cause the
ice and snow to avalanche from the ridges.
4
Figure 2.--"New" lake near the upper end of Long Lake, and it:; tributary glaciers, August 23, 1984.
5
Figure 3.--"Sideways" glacier in tributary valley to Long River, August 23, 1984.
6
I
I
I
I
I
I
I
.~·~-.. .
Figure 4.--A valley glacier at head of Crat~r Creek, August 23, 1984.
7
I
I
Figure 5.--Snow conditions on "Bench" glacier tributary to "New" lake, August 23, 1984.
8
I
~-·
Figure 6.--Late summer snow line approximating extent of glacier cover in Long Lake basin,
August 23, 1984.
9
EFFECTS OF GLACIER ABLATION ON RUNOFF
The presence of glaciers in a watershed has several effects on runoff. First,
glaciers usually have a moderating effect on runoff extremes. Glacier runoff tends
to be greatest during sunny weather, whereas nonglacial runoff tends to be greatest
during cloudy weather with rainfall. Ras1ns with a mixture of glacier and
nonglacier areas such as Long Lake and Crater Lake basins have lower variability of
streamflow because of these opposite trends. Also, glaciers occupy are<ts with
relatively high precipitation and thus are sources of higher runoff. Mayo (1984)
estimates that runoff from glacier basins in the maritime regions of Alaska is
about twice that of nonglac:fCll basins. Finally, as glaciers grow or shrink,
storage changes within the glaciers will affect runoff. The magnitude of the
effect is a function of the volume of storage change over the period of time in
which the change occurs. The glaciers within Long and Crater Lake basins have
undergone recession and reduction in ice volume since they were first photographed
from the air in 1929, and probably since the latter part of the 19th century if
their behavior was similar to that of most glaciers in southeastern Alaska.
Glacier ice and perennial snow covered about 25 percent of the combined area
of Crater Lake and Long Lake basins in September 1984, compared to 30 percent in
August 1948 (tab] e 2). This represents <'l. reduction of snow and ice area of 2.19
mi 2 over a span of 36 years. Much of the reduction in area of snow and ice occur-
red at lower altitudes. The greatest change in ice thickness also occurred at
altitudes below 2,500 ft. Above an altitude of about 2,500 ft, there have been
comparatively small changes in area and thickness of snow and ice.
Table 2.--Area in square miles measured on maps compiled from
aerial photographs
Basin and area
Crater Lake
Drainage area
Snow and ice
Long Lake
Drainage area
Snow and ice
Total snow and ice
August 1948
11.27
3.19
30.11
9.38
12.57
September 1984
11.28
2.81
30.13
7.57
10.38
The total area covered by perennial snow and ice in the two basins decreased
from 12.57 mi 2 in 1948 to 10.38 mi 2 in 1984. Ice-thickness reduction at the cross
sections (plate I) across the ice tongues and valley glaciers ~veragerl about 140 ft
during the same time span. Applying a thickness reduction of 140 ft to the area of
permanent ice and snow below and altitude of 2,500 ft in 1948 (2.61 mi 2 ) results in
ice loss from 1948 to 1984 equal to 1.12 x 10 10 ft 3 • The recluction in ice volume
above 2,500 ft is estimated to be equal to that below 2,500 ft --a lesser thick-
10
ness change, but the area of higher altitude glaciers is about four times as great
as that of lower valley glaciers. The loss of this much ice, 2.04 x 10 10 ft 3 ,
would contribute an average of 16 ft 3 /s to streamflow over the 36-year period
(1948-84). This amounts to an average annua] yield of about 11,700 acre-ft of
water, or a total yield for the period of record, 1948 to 1984, of about 421,000
acre-ft.
The combined average discharge from the two basins is about 650 ft 3 / s (see
tables 6 and 8 later in the text). The estimated runoff contributed by glacier
recession is about 2.5 percent of the total runoff. This estimate is subject to an
unquantified error in photogrammetric measurement that is probably small with
regard to area, but may be large with regard to thickness. A larger factor of
uncertainty rests in the judgment of how accurately the thickness reduction applies
to the glacier area. Stereoscopic examination indicates that little thickness
change has occurred in the higher altitude glaciers along the divides. The
estimate of 2.5 percent of the avera?,e flow seems reasonable, and is probably on
the Jarge side, but should be considered only a "ballpark" figure. Even if twice
the estimated amount of ice was lost, glacial melt would amount to only 5 percent
of the average·annual flow.
1 1
STREAMFLOW RECORDS
by Robert D. Lamke
Introduction
Streamflow data were collected at U.S. Geological Survey station 15038000,
Crater Creek near Juneau, from February 1913 to December 1932 (records are
fragmentary from January 1921 to June 1927). Streamflow data were collected also
at five nearby stream-ga~ing stations at various times within the 1913-32 period
(table 3). Data are also available for some of the sites after 1932. Analysis of
the quality of the data collected in the 1913-32 period was made and the discharge
records were entered in the U.S. Geological Survey's WATSTORE Daily Values File.
These records can be used to estimate discharges to fill in the fragmentary record
of Crater Creek during 1913-32 and to extend the Crater Creek record during the
1933-68 period.
Table 3.--Gaging stations and periods of record in the Daily Values File of
HATSTORE
Station
number
15030000
15032000
15034000
15036000
15038000
15040000
Station name
Period of record in WATSTORE
[Water years, or partial (f) water
years]
Sweetheart Creek near Juneau 1 915 f , 1 916 , 191 7 f , 1918 f , and
1919-27
LonR Lake 0utlet near Jupeau
Long River near Juneau
Speel River near Juneau
Crater Creek near Juneau
Dorothy Creek near Juneau
12
1913f' 1914-15' 1916f
1916-24, 1927f, 1928-32, 1933f,
1951-73
1916f, 1917-18, 1960f, and
1961-75
1913f, 1914-20, 1921£, 1923f,
1924f, 1927f, 1928-32, 1933f
1930-41, 1942f, 1943, 1944f,
1945-67, 1968f
History
Gaging stations were established in January 1913 at the outlets of Long and
Crater Lakes by FPC (Federal Power Commission) applicants. These stations were
operated until 1921 by the Speel River Project, in cooperation wfth the U.S.
Geological Survey and U.S. Forest Service. Station 15032000, Long Lake outlet, was
moved downstream on November 10, 1915 ancl established as Station 15034000, Long
River. During water years 1914-33, discharge data were sporadically collected at
three other sites in the vicinity of Long and Crater Lakes. The USGS established
Station 15030000, Sweetheart Creek, in August 1915. Station 15036000, Speel River,
was operated from July 1916 to September 1918 by the Speel River Project. The
Geological Survey discontinued its participation in the operation of these stations
in April 1921. The Forest Service continued to operate these stations at a reduced
level of effort for the FPC until 1927.
In 1927, another FPC applicant, George T. Cameron, applied for a power license
on Crater and Long Lakes, and the stations on Crater Creek and Long River were
operateil in conjunction with the Forest Service until 1933. During this same
period, Mr. Cameron applied for a power license on Dorothy Creek, a stream adjacent
to the Long River drainage. Station 15040000, Dorothy Creek, "1as established in
October 1929. This station was openttecl by the Forest Service until 1946 and
subsequently, through December 1967 by the Geological Survey. The USGS reactivated
Stations 15034000, Long River, and 15036000, Speel River, in October 1951 and May
1960, respectively. Discharge data have been published in various reports of the
Geological Survey of which Bulletin 836-C, "Surface Water Supply of Southern
Alaska, 1909-30" (Henshaw, 1933) and Wate-Supply Paper (WSP) 1372, "Compilation of
Records of Quantity and Quality of Surface Waters of Alaska through September 1950"
(U.S. Geological Survey, 195 7) are of principal interest. Additional information
is included in "Report to Federal Power Commission on Water Powers of Southeastern
Alaska" (Dart, 1924) and in "Water Powers Southeast Alaska" (Federal Power Commis-
sion and U.S. Forest Service, 1947).
Streamflow Analysis
Streamflow records collectecl prior to 1946 in Alaska are summarizen as monthly
mean flows in WSP 1372. Prior to publication of WSP 1372, the origtnal data and
computations of discharge at all stream-gaging stations in Alaska were reviewed and
some computations were revised. If the quality of the record seemed poor and if
revision of the discharges was not feRsible or practj cal, the data were not
included in WSP 1372. For some stations, discharges were estimated to complete the
record for a month or a water year. Streamflow data for these years were published
as monthly summaries in WSP 1372.
The WATSTORE system (Hutchinson, 1975) of the Geological Survey will store
only daily values and has no provision for entry of monthly summaries. Many daily
discharges for years prior to 1946 were never entered into the Daily Values File,
although the daily discharge values were available from the original worksheets and
from notes made during the 1950 compilation analysis. Some discharges for the
periods of missing daily record in the original computations were estimated as
13
totals for the period or the monthly totals vJere estimated. These totals were
estimated by comparison with daily discharge records at nearby stations, if
available.
In the process of determining dnily flows for periods of missing record,
least-squares regression equations for each month were computed using available
daily discharge values for the station record being analyzed as a function of the
actual record at a nearby station (or stations) (Lamke, 1984, p. 37-45). These
equations were then used as guides in estimating daily discharges for the station
of interest. If daily discharges during a period of missing record did not vary
greatly or if records were not available for the nearby stations, average values
for the missing record periods were entered into the WATSTORE Daily V8lues File.
Daily discharge values for all the months show"TI in table 3 and in WSP 1372 are now
stored in WATSTORE.
Discharge values for periods of missing record at Crater Creek were estimated
by comparing with records at Long River and conversely, Crater Creek records were
used to estimate missing records of daily discharge at Long River. The daily
discharges at these stations in adjacent basins have a cross-correlation
coefficient of 0.78. For concurrent periods of missing record at Crater Creek and
Long River, the record at Sweetheart Creek was used to estimate discharge~ at those
stations. Crater Creek and Long River daily ci scharges have cross-correlation
coefficients of 0. 55 and 0. 74, respectively, with dailf discharges at Sweetheart
Creek. The Sweetheart Creek station had less Missing record than the stations at
Crater Creek and Long River.
A correlation coefficient is a measure of how well the data fit the linear
relation between variables. The term "cross" correlation coefficient is used
herein to denote that the daily discharges were transformed to remove seasonal
trends before the linear relation was calculated (see Lamke, 1984, p. 52-53). The
dai]y flows for each day of the year were standardized by subtracting the mean for
that day of the year and dividing by the standard deviation for that day of the
year. If the daily discharges were not transformed, the resultant correlation
coefficient for Crater Creek and Long River js 0.96 and the resultant correlation
coefficients of Crater Creek and Long River with Sweetheart Creek are 0.82 and
0.86, respectively.
Seasonal flow characteristics of Sweetheart Creek differ from those of the
other two streams because only one-tenth of the Sweetheart Creek basin is covered
by glaciers while glacier ice covers one-fourth of the basins of Crater Creek and
Long River. The percentages of lake aree1 in the three basins are comparable.
Crater Creek's drainage area is about one-third that of Long River and Sweetheart
Creek. Crater Creek has a more rapid runoff response to rainfall, larger values of
peak runoff per unit area, and less storage to support low fJows than either
Sweetheart Creek or Long River.
Correlations between flows at Long River and at Crater Creek versus flows at
other nearby stations were also examined. Daily discharge values at Speel River
correlate poorly with values for other nearby stations, probably because the
drainage area of Speel River is much lar~er than the other streams.
14
The cross-correlation coefficients of daily discharges at Crater Creek and
Long River with Dorothy Creek are 0.61 and 0.68, respectively. Because of the
relatively higher altitudes and the series of lakes in the Dorothy Creek drainage
basin, the cross-correlation coefficient improves to 0.71 if daily discharges at
Dorothy Creek are compared to the previous day's discharge at Crater Creek.
Dorothy and Crater Creeks have only 3 years of concurrent record and the Dorothy
Creek gage was moved upstream 0.8 rni in 1937. For these reasons, any extension of
the Crater Creek record based on the Dorothy Creek record should be done with
caution.
Results
The results of the analysis of the six stations' records are summarized in
tabulations of monthly discharges for the period of record (tables 4-9). The
months with record shown in these tables for the periods prior to 1950 are the same
as those in WSP 1372. Discharges given in this report are generally the same as
those shown in WSP 1372, except for minor differences due to rounding procedures.
Significant differences in monthly averages are footnoted in the tables for months
for which there were arithmetical errors in the original records or an incorrect
value was inadvertently shown in WSP 1372.
The tables contain statements about the estimated accuracy of the daily
discharge records. "Excellent" means that about 95 percent of the daily discharge
values are estimated to be within 5 percent of the true discharge, "good" within 10
percent, and "fair" within 15 percent. "Poor" means that daily discharges have
less than "fair" a.ccuracy.
Footnotes are shown in the tables for periods of estimated record. The mean
discharges for any month have been designated as "estimated" if data are available
for fewer than 6 days during the month, and "partly estimated" if data are
available for 6 to 25 days. No footnote is used if fewer than 6 days of record are
missing. The accuracy of streamflo¥r records depends on the stability of the
stage-discharge relation, on the accuracy (and frequency) of stage observation and
measurements of flow, and on the interpretation of those data.
15
YEAR
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
AVERAGE
PERCENT
• b
OCT
a412
621
376
489
349
598
a346
b495
c458
304
489
448
11.1
Table 4.--Sweetheart Creek near Juneau (15030000)
(Formerly published as Sweetheart Falls Creek near Juneau and
Sweetheart Falla Creek at Port Snettisham)
LOCATION: (REVISED) .--Lat 57"56'35", long 133"40'55", in NEINWI sec. 25, T.45S., R.73E., City and Borough
of Juneau, Hydrologic Unit 19060000, in Tongass National Forest, 300 ft upstream from mouth, 2.0 mi
downstream from Lower Sweetheart Lake, and 37 mi southeast of Juneau.
DRAINAGE AREA.--36.8 mi 2 , revised.
PERIOD OF RECORD.--August 1915 to March 1917 and June 1918 to September 1927.
GAGE.--Water-stage recorder. Altitude of gage is 50 ft, from topographic map.
AVERAGE DISCRARGE.--10 yeara (water years 1916, 1919-27), 335 ft'/s, 125 in/yr, 242,700 acre-feet/yr.
COOPERATION.--Records subsequent to 1920 furnished by U,S. Forest Service.
REHARKS.--Stage-discharge relation permanent, but occasionally affected by ice. Records considered
excellent except those for periods of missing record or when discharges are greater than 1,300 ft 3 /a,
which are fair.
CORRECTIONS.--Minor differences in monthly discharges between those shown herein and those published in
WSP 1372 occur because of changes in rounding. However, other monthly and annual discharges have been
corrected because of arithmetical errors in the original recorda; the corrected valuea are footnoted
in the following table.
MONTHLY AND ANNUAL MEAN DISCHARGE, IN CUBIC FEET PF.R SECOND, BY \lATER YEAR
NOV DEC JAN FEB MARCH APRIL HAY JUNE JULY AUG SEPT
* * a501 a524
al68 101 38.3 38.1 a43.0 al56 368 787 a501 a582 636
194 87.7 56.5 12 7 a49.5
753 623 666 619
393 193 256 53.9 42.2 147 342 535 613 577 604
154 136 a227 93.4 a39.3 50.9 237 622 568 640 418
275 53.0 a63.0 a95.0 a64.0 115 395 630 a479 428 425
al63 292 91.0 b30.0 b25.0 b1!5 419 677 574 552 b525
403 116 57.9 a93.6 133 230 475 626 483 362 710
a488 203 a67.3 b40.0 b74.4 all5 586 829 774 585 821
287 al63 b38.5 b30.0 44.8 84.1 a477 692 637 372 423
353 491 a574 144 263.0 422 363 451 344 301 238
b313 a223 blOB b37 .3 77.3 97.3 396 767 481 342 592
290 187 143 71.0 77.7 153 406 670 552 492 545
7. 2 4.6 3.5 1.8 1.9 3.8 10.1 16.6 13.7 12.2 13.5
No data for part or all of the month.
No data for part of the year.
Partly estimated .
Estimated
Corrected.
16
YEAR
319
346
308
282
341
336
424
311
355
328
335
100
YEAR
1913
1914
1915
1916
AVERAGE
PERCENT
•
a
Table 5.--Long Lake Outlet near Juneau (15032000)
(Formerly published as Long Lake Outlet at Port Snettisham)
LOCATION.--Lat 58"10'00", long 133"43'30", in II!SE! sec.!, T.43S., R.71E., City and Borough of
Juneau, Hydrologic Unit 19060000, in Tongass National Forest, 30 ft upstream from outlet of
Long Lake, 1.3 mi upstream from Indian Lake, 5 mi upstream from mouth, and 26 mi southeast
of Juneau.
DRAINAGE AREA.--30.2 mi 2 •
PERIOD OF RECORD.--February 1913 to October 1916.
GAGE.--Water-stage recorder. Altitude of gage is BOO ft, from topographic map. No gage prior
to January 1914.
COOPERATION.--Current-meter and float measurements obtained by Kennedy and Lass, a Federal Power
Commission applicant during 1913. Recorda for 1913-15 furnished by Speel River Project.
REMARKS.--Stage-discharge relation permanent and unaffected by ice. Records for calendar year
1913 are poor and are fair thereafter (except for periods of missing record. Records for
1913 were computed from current-meter and float measurements and short periods were estimated.
Minor differences in monthly discharges between those ahown herein and those published in WSP
1372 occur because of changes in rounding.
MONTHLY AND ANNUAL MEAN DISCHARGE, IN CUBIC FEET PER SECOND, BY WATER YEAR
OCT NOV DEC JAN FEB MARCH APRIL HAY JUNE JULY AUG SEPT
• • • 120 143 131 449 1125 1895 1761 1267
1155 375 163 50.0 67.8 83.3 Ill 338 724 1207 1063 629
554 273 121 a96.0 a46.0 sl25 202 529 841 1097 1256 1002
507 • •
739 324 142 73.0 78.0 117 148 439 897 1400 1360 966
11.1 4.8 2.1 1.1 1.2 1.7 2.2 6.6 13.4 20.9 20.4 14.5
No data for part or all of the month.
No data for part of the year.
Estimated.
17
YEAR
501
515
508
100
YEAR
1916
1917
1918
1919
1920
1921
!922
1923
1924
1927
19n
1929
1930
1931
1932
1933
1952
1953
1954
1955
1956
195 7
1958
1959
1960
1961
1962
1963
1964
1965
1966
196 7
1968
1969
1970
1971
1972
1973
Table 6.--Long River near Juneau (15034000)
(Formerly published as Long River below Second Lake, at Port Snettiaham)
LOCATION.--Lat 58°10'00", long !3)0 41'50", in W!SF.I aec.6, T.43S., R.72E., City and Borough of Juneau,
HydrologicUnit 19060000, in Tongass National Forest, on right bank 0.4 mi upstream from Indian Lake,
1 mi down-stream from Long Lak•, and 27 mi southeast of Juneau.
DRAINAGE AREA.--32.5 mi 2 •
PERIOD OF RECORD.--October 1915 to September 1924, October to December 1926, June 1927 to Hay 1933, and
October 1951 to September 1973.
GAGE.--Water-stage recorder. Altitude of gage is 183 ft, from topographic map. Prior to Oct. I 1929,
at site 600 ft upstream.
AVERAGE DISCHARGE.--)! years (water yeara 1916-24, 1928-32, 1952-68), 464 ft'/s, 192 in/yr, 335,900
acre-ft/yr, prior to regulation at Long Lake and diversion for Snettisham Power Project. Discharges
for water years 1969-73 are not included in the figure above.
COOPERATION.--Records for 1921-33 furnished by U.S. Forest Service.
REMARKS.--Stage-diacharge relation is permanent; generally affected by ice during vinter months,
December to April. Recorda for 1916-22 and 1928-33 are good except those for periods of missing
record which are fair. Records for 1923-27 are fair. Recorda good for 1951-73 except thoae for
winter periods and periods of misaing record, which are poor. Flow has been regulated at Long Lake
since July 16, 1969.
CORRECTIONS.--Hinor differences in monthly discharges
in WSP 1372 occur becauae of changes in rounding.
have been corrected because of arithmetical errors
are footnoted in the following table.
bet~een thoae shown herein and those published
However, other monthly and annual dischargea
in the original recorda; the corrected values
OCT
b527
605
652
SOJ
aS26
)81
688
476
b563
a495
347
S2S
1079
548
689
c669
a310
all24
909
466
J3B
J74
587
748
566
818
959
592
a751
692
924
710
398
401
dl017
cl899
d435
d615
MONTilLY A:liD ANNUAL DISCHARGE, IN CUBIC FEET PER SECOND, 1\Y wATER YEAR
NOV
a!J6
145
660
34J
s!92
262
a208
a523
521
ac)J3
al26
364
486
560
181
122
129
445
143
470
212
435
449
254
274
336
205
406
a127
272
155
228
362
178
d200
d293
dl57
dl50
DEC
a98.2
86.4
a94.6
181
bl28
b60.0
278
bl04
b221
a280
b49.8
315
al44
329.0
a84.4
a73.6
a90.9
121
139
366
b55
a34 7
al19
bl43
201
292
SS.7
301
b218
a204
112
55.0
122
92.5
d21. 9
d38 .I
ad66
d63. 9
JAN
a49.9
87.5
a97.5
a209
bl80
b68.0
b91.0
b62.0
b78.0
a186
al97
b20.0
! 52
a55.0
45.0
bJB.O
n57.8
a70.9
a88.7
b30.0
al22
b!93
b70.0
a91. I
130
183
145
hl25
b226
aS2.2
a50.9
59 .I
26.4
d5.$5
d59.5
bdl7.0
d49.l
FEB
b49.4
alJO
b4l.O
b55.0
94.7
b95.0
b30.0
b85.0
bSO.O
al37
42,8
b45.0
265
b55.0
40.0
b3B.O
a6 7.2
a275
55.0
bJO.O
b45 .0
b70.0
b70.0
b54.6
127
78.2
2!5
biOS
bll9
b45.2
b55.4
134
b24.7
d3 .9
d42 .0
bdlO.O
bd59.3
!".ARCH
b50.0
51.8
b26.0
bSO.O
a45.6
b69.0
b25.0
bl17
b90.0
APRIL
129
a66.5
b 71. l
bl25
b52.0
al!O
•cl20
ac240
bl35
al21 219
105 83.1
b60.0 nl37
a51.6
b60.0
41.2
b49. 7
a48.3
h59.7
60.0
b40.0
b35.0
bSO.O
b60.0
7!.8
100
91.6
109
a69.5
bl25
b6 5. 2
b45.S
221
bS5.7
d8.4
•124
a108
301
alSO
a84.8
b50.0
67. I
b70.0
87. I
•ISO
a99.3
147
202
85.1
al\5
156
bl09
o\30
b47.8
110
112
dl8.8
d26.3 d68.1
bdl9.5 hdl2.8
hd43.9 hd88.5
MAY
253
335
a300
aJ09
a235
388
a40S
436
575
554
348
317
a489
a357
539
439
572
a321
286
489
472
549
427
472
507
305
b388
312
b250
383
~386
434
490
d980
d282
od96.9
d348
JtrSE
864
695
744
aS45
580
715
704
724
910
893
815
826
712
961
a7S7 •
733
943
754
670
591
801
1043
905
705
1017
797
740
992
b691
799
1159
654
1165
d1791
JULY
855
995
1065
b864
918
851
913
929
1169
960
1076
884
900
955
821
1043
a919
816
1036
1021
830
979
•1210
1044
1358
901
945
1201
n868
929
865
902
dll97
d920
d724 d990
d57.3 d31.6
d616 d884
AUG
I 069
1293
1219
bl050
1198
857
! 046
a973
al053
91.5
a8~7
hc841
1079
1093
877
9 58
!018
631
1145
1353
807
989
8895
973
1482
833
757
852
b877
1056
1099
b673
dl849
d934
dll95
d603
d! 1 I 7
SEPT
1043
923
1062
b!OOO
641
c702
829
hcl132
bl080
960
a831
a754
820
821
9 75
1103
881
909
~· 5
668
1024
530
583
9 79
7!9
1!03
1237
489
5P8
1113
132 2
bl278
dl9ll
d706
d840
d76Q
d676
YEAR
428
454
50S
439
401
381
448
485
538
447
44J
486
530
419
425
527
424
466
410
450
478
458
466
595
469
497
452
421
483
504
446
d628
d513
d458
dl90
d)95
AVERAGE
PERCENT
622
11.2
305
5.5
166
3.0
103
1.9
87.5
1.6
70.8
l. 3
121
2.2
401 795 970 997 904 464
* No data for part or all of th• month.
-No data for part of the year.
Does not include water ye•r• 1969-73.
8 Partly estimated.
b Estimated.
Corrected.
d Flow regulated aince July 16, !969.
7.2 14.3 17.5 18.0 16.3 100
18
YEAR
1916
1917
1918
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
AVERAGE
PERCENT
8
b
Table 7.--Speel River near Juneau (15036000)
(Formerly published as Speel River at Port Snettisham)
LOCATION.--Lat 58"12'10", long 133"36'40", in SEINE! sec. 27, T.42S., R.72E., City and Borough of Juneau,
Hydrologic Unit 19060000. on right bank 0.8 mi downstream from Long River, 8 mi upstream from mouth at Speel
Arm of Port Snettisham, and 30 mi southeast of Juneau.
DRAINAGE AREA.--226 mi'.
PERIOD OF RECORD.--July 1916 to September 1918, May 1960 to September 1975.
GAGE.--Water-stage recorder.
at site 0.2 mi upstream.
Altitude of gage ia 140 ft, from topographic map.
May 25 to Sept. 28, 1960, nonrecording gage.
Prior to September 1918,
AVERAGE DISCHARGE.-17 years (water years 1917-18, 1961-75), 2,585 ft 5 /s, 155 in/yr, 1,873,000 acre-ft/yr;
average not corrected for Long Lake diversion.
REHARKS.--Records generally fair (and occasionally good) for entire period except those for periods of no
gage-height record and for winter periods, which are poor. Monthly and annual flows not corrected for
regulation at Long Lake, since July 16, 1969, and for subsequent diversion from Long River.
CORRECTIONS.--Minor differences in monthly discharges between those shown herein and those published in
WSP 1372 occur because of changes in rounding. However, other monthly and annual discharges have been
corrected because of arithmetical errors in the original records; the corrected values are footnoted in
the following table.
MONTHLY AND ANNUAL MEAN DISCHARGE, IN CUBIC FEET PER SECOND, BY WATER YEAR
OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT YEAR
* * * * * a5423 7047 a6220
a2890 7.60 b420 b356 b500 a170 ac347 1697 a3572 a5671 b8500 ac5449 2544
a4226 a3548 b500 a378 cl75 acl38 357 1570 b3963 a6281 a7420 b7152 2990
* * * * * * 4062 6320 6306 5596
b4 Jl7 a!599 1294 551 554 375 891 3477 6576 8488 9951 5271 3620
4565 859 a324 bl002 b511 b430 b418 bl525 4283 5931 5611 6070 2642
3065 1867 1152 b657 b936 b479 b492 bl710 4630 6242 5371 6773 2789
3786 a605 bll04 b669 b6!9 a419 a772 bl644 b5867 b7103 b5281 b2520 2544
3282 1347 a987 b908 a356 430 568 sl470 b4583 5901 5780 3770 2464
4100 769 441 bill bl54 27 5 680 1408 3901 b4990 a5475 b5767 2358
b3890 b!003 b214 b207 b201 al75 310 2034 6455 5248 6717 a6825 2785
al996 bl468 a420 208 582 960 482 2779 3812 5659 a3965 b5717 2341
1309 b514 b286 b68.9 b45.9 al25 530 3114 7006 6645 7173 4876 2656
2813 2204 669 159 368 338 458 2612 5622 5607 6060 5300 2695
a2727 bll43 bl48 b237 b259 91.7 279 1659 5034 6337 6441 3990 2377
2089 683 239 105 100 263 183 1902 3709 5775 6596 b3938 2143
a3289 bl020 b351 b261 b323 b227 b439 bl706 b3330 b4887 a6233 4088 2194
2050 317 97.4 71.0 79.8 93.5 310 1925 3856 a5004 a5600 5343 2074
5736 2063 734 264 103 63.4 283 1780 4026 7220 4586 5587 2722
3290 1281 552 369 345 297 459 2001 4683 6039 6322 5276 2585
10.6 4.1 1.8 1.2 1.1 1.0 1.5 6.5 15 .I 19.5 20.5 I 7 .I 100
No data for all or part of the month.
No data for part of the year.
Partly estimated.
Eatimated.
Corrected.
19
YEAR
1913
1914
1915
1916
1917
1918
1919
1920
1921
1923
1924
1927
1928
1929
1930
1931
1932
1933
Table B.--Crater Creek near Juneau (15038000)
(Formerly published ss Crater Lake Outlet at Port Snettisham)
LOCATION.--Lat 58"08'15", long 133"46'15", in SEISEI sec. IS, T.43S., R.71E., City and Borough of
Juneau Hydrologic Unit 19060000, in Tongass National Forest, 100 ft upstream from outlet of
Crater Lake, 1 mi upstream from mouth, and 26 mi southeast of Juneau.
DRAINAGE AREA.--11.4 mi 2 •
PERIOD OF RECORD.--February 1913 to December 1920, June to August 1921, October to December 1922,
June to September 1923, June to September 1924, and June 1927 to December 1932.
GAGE.--Water-stage recorder. Altitude of gage is 1,010 ft, from topographic map. No gage prior
to January 1914. Prior to March 1929, staff gages at the beach at various sites ~ere generally
read at frequencies ranging from once a day to once weekly during the ~inter. Supplemental
~ater-stage recorder at the beach, March 1929 until Hay 1932, operated during winter periods.
AVERAGE DISCHARGE.--12 years (water years 1914-20, 1928-32) 193 ft'/a, 230 in/yr, 139,800 acre-ft/yr.
COOPERATION.--Current-meter and float measurements obtained by Kennedy and Lass, a Federal Power
Commission applicant, during 1913. Records for 1913-15 furnished by Speel River Project and
recorda for 1921-33 furnished by U.S. Forest Service.
REMARKS.--The stage-discharge relation at the lake outlet ia permanent. The recorda that were
computed using this relationship for ~ater y~ars 1916-20, and 1928-32, are good to excellent
and those for other periods are fair to good. Records are poor for periods of missing record
and calendar year 1913. Because of inaccessible locatinn and deep ana~, the gage at the lake
could not be operated during the ~inter. The recorda for several ~inter periods were computed
using stage-discharge ratings for various sites on the beach. The record obtained at the beach
is fair. Prior to December 1929, discharges at the beach ~ere not adjusted for the extra square
mile of lo~-altitude drainage area bet~een the bench ond the outlet. Baaed on the corrections
used in ~ater years 1930-32, the annual discharge values for the other years when the gages at
the beach ~ere used to compute ~inter records should be reduced by about 2 percent. This
reduction vould only lo~er the average discharge for the period of record from 193 to 190 ft 3 /s.
No further attempt has been made to adjust the individual monthly means prior to December 1930.
The months during ~hich gages at the beach ~ere used are shown in the accompanying table.
CORRECTIONS.--Minor differences in monthly discharges
in WSP 1372 occur because of changes in rounding.
have been corrected because of arithmetical errors
footnoted in the follo~ing table.
bet~een those shown herein and those published
However. other monthly and annual discharges
in original records; corrected values are
MONTHLY AND ANNUAL MEAN DISCHARGE, IN Cl'BIC FEET PER SECOND, RY WATER YEAP
OCT NOV DF.C JAN ITB MARCH APRIL MAY Jl'NF. JULY AUG
* 47.0 48.3 57.3 203 531 RB30 858
260 al08 38.2 d20.9 d45.0 d36. 7 d52.8 144 272 51 7 409
313 104 d23.9 d36.1 dl7.2 d44.6 d74.0 2 35 414 497 469
185 44.9 b33.0 bl8.0 b!B.O b19.0 b44.0 b90.0 b370 370 464
2 70 a51.2 ad 32. 7 d34.9 d44.5 d22.5 d23.8 d142 305 441 539
251 b250 b35.0 ad33.2 cdl6.4 dl2.7 d20.7 Rdi29 c359 4R2 591
202 133 65.4 68.4 a14.6 b12 .o b4 7 .o •118 217 417 •511
a209 a66.R b45.0 b100.0 b35.0 b16.0 b20.0 a53.3 177 406 5)2
bl40 a91.8 a24.7 * b305 399 a360
202 158.0 a40.7 297 452 483
a400 5R4 566
a350 377 357
bl35 b48.0 b25.0 d88.7 d30.7 d40.0 d42.3 d193 a381 528 •377
194 113 81.9 ad76.0 adl9 .I d49.4 d29.3 •91 .9 382 419 404
463 222 ae60.2 b4.9 h9.0 b14.7 ae34.4 el04 30R 420 484
22 5 25 7 el46 e68. 2 ael02 e22.3 e4 5. 3 e211 402 417 4 74
3 34 ae72.7 e27.5 b20.0 b20.0 blS.O e32.9 ••105 a2R4 362 366
c307 42.2 26.5
AVERAGE
PERCENT
246
10.3
117
4.9
4 7 .I
2.0
47.4
2.0
32.2
1.4
27.2
1.1
40.3
1.7
140
5.9
338
14.2
466
19.5
485
20.4
No data for pArt or all of the month.
No data for part of the year.
a Partly estimated.
b Fstimated.
Corrected,
d Record obtained at beAch for part or all of th~ month.
Record obtained at beach for part or all of the month. Cnrr~ction used to account for differPnce
in drainage areas at the beach and at outl~t of Crater T.ake.
20
SEPT
491
266
389
b470
a361
a411
b420
26 2
a502
581
R352
343
34 7
359
c35 7
429
396
16.6
YEAR
182
719
I ?A
190
c217
187
161
187
185
208
228
173
193
100
..
Table 9.--Dorothy Creek near Juneau (15040000)
(Formerly published as Dorothy Creek at Taku Inlet)
LOCATIOli.--Lat 58"13'40", long 134"02'25", in NWlSIIl sec. 18, T.42S., R.70E., City and Borough of Juneau,
Hydrologic Unit 19060000, in Tongass National Forest, on left bank 0,7 mi do~stream from Lake Bart,
0.8 mi upstream from mouth at Taku Inlett 3 mi downstream from Lake Dorothy, and 14 mi southeast of
Juneau.
DRAINAGE AREA.--15.2 mi•.
PERIOD OF RECORD.--October 1929 to October 1941, September 1942 to December 1943, and June 1944 to
December 1967.
GAGE.--Water-stage recorder. Altitude of gage is 350 ft, from topographic map. Prior to Sept. 14,
1937, at site 100 ft upstream from mouth.
AVERAGE DISCRARGE,--36 years (water years 1930-41, 1943, and 1945-67), 143 ft 5 /s, 128 in/yr, 103,600
acre-ft/yr.
COOPERATIOli,--Records prior to water year 1946 furnished by U.S. Forest Service and George T. Cameron,
a Federal Power Commission applicant.
REMARKS.--The stage-discharge relation is permanent for all practical purposes. Stage-discharge relation
affected by ice only in extremely cold weather at the most recent location; however_ It ~as difficult
to obtain winter records at the former site4 Records good to excellent except those for periods of no
gage-height record and winter periods, ~hich are poor to fair.
CORRECTIOliS.--Minor differences in monthly discharges between those shown herein and those published in
WSP 1372 occur because of changes in rounding. However~ ocher monthly and annual discharges have been
corrected because of arithmetical errors in the original recordsi the corrected values are footnoted
in the following table.
MONTHLY AND Al1NUAL KEAN DISCHARGES, Ill CUEIC FF.f.T PF.R SECOND, BY IIATER YEAR
YEAR OCT NOV DEC JAN FEB MARCH APRIL MAY JT!NE JULY AUG SEPT YEAR
1930 342 152 64,4 10.6 13.2 20.8 48.1 75.2 197 330 373 283 160
1931 195 194 100 47.0 70.9 a22.3 a34.0 117 329 311 361 300 174
1932 209 64.1 17.0 18.4 al3.9 13.4 26.8 70.6 250 290 281 274 128
1933 214 42.6 a22.6 a19.4 15.6 cl0.2 21.8 86.7 150 251 269 184 108
1934 169 158 b)2.0 aiO.O 12.0 15.0 b20.0 b60.0 b250 277 406 250 139
1935 c2!0 82.5 53.9 c18.5 b10.0 a18.0 19.1 54.4 a164 396 •304 202 129
1936 202 57.1 a82.5 bl8.0 bl3.0 al9.0 b35. 7 109 317 299 272 357 149
1937 455 284 a113 a25.0 a!S.O 22. 7 26.1 66.5 298 b250 b300 a340 184
1938 384 85.9 48.9 ac39.4 a37.6 c68. 7 21.2 125 205 279 245 391 162
1939 232 74.7 55.0 32.2 23.8 17.4 23.4 72.8 225 342 436 258 150
1940 258 141 74.9 26.7 33.3 16.6 37.4 115 216 320 403 316 164
1941 223 70.0 31.8 17.4 23.4 b23.0 53.6 94.~ 251 323 217 148 124
1942 204 • • * * * * • * a287
1943 a252 a53.4 31.2 a37.3 b20.0 b40.0 a62.3 95.1 226 383 338 )8) 161
1944 394 158 110 * • .. AJ36 298 290 213
1945 320 140 84.2 20.2 14.3 24.8 27.1 117 a243 b330 a262 a310 159
1946 398 a47,1 bl9.6 bl5.3 b14.9 A}7.2 al9.0 b140 b282 b266 332 231 149
1947 193 130 26.0 22.9 18.2 8~.9 47.4 118 278 266 243 bJM 151
1948 b212 a89.7 62.8 36.4 19.2 16.1 13.1 134 320 a304 a273 387 156
1949 162 123 b36.7 b31.0 b15.1 18.5 28.9 116 206 271 307 277 133
1950 172 355 a36.6 bl2.9 b!O.O bll.1 13.6 72.5 216 287 250 302 145
1951 97.5 a) 1. 7 14.3 18.5 14.6 16.8 23.4 91.6 280 322 216 227 113
1952 144 45.9 22.1 a17.3 17.4 I 5.1 22.4 ao.s 180 )06 289 334 12J
1953 327 159.0 32.7 al9. I bl9.5 21.2 22.6 118 249 317 a33J 284 159
1954 236 92.5 30.5 25.8 b65.0 b25. 4 16.5 64.5 198 241 198 24! 120
1955 al35 114.0 72.4 28.4 18.6 19.4 20.3 6!.5 167 325 340 253 130
1956 118,0 53.0 21.4 11.3 10.0 14 .I 20.2 Ill 171 302 440 240 127
195 7 121 a62.9 biOI 59.3 17. 3 14.3 17.4 101 240 258 249 288 130
1958 222 170 33.8 )9.1 16.0 14.1 23.3 M10) 314 782 332 169 144
1959 183 103 37.0 a23. 3 RJ8.0 a23.4 22.7 83.0 249 375 318 160 134
1960 149 72,8 46.5 26.6 18.3 15.5 29.2 103 197 350 309 297 135
1961 259 117 65.1 49.2 33.4 25.4 42.1 120 318 419 465 238 181
1962 272 61.3 22.1 34.5 2 7 .o 18.8 22.7 55.9 241 307 288 358 143
1963 153 164 107 49.7 58.2 )7.5 22.7 96.5 204 298 251 380 152
1964 252 49.6 41.6 37.1 29.4 23.2 2 7.1 5!.8 284 359 213 142 131
1965 201 85.7 48.5 58.0 32.3 26.6 22.1 62.5 200 265 225 225 122
1966 238 94.0 31.2 a14.4 bl0.9 al6.7 25.9 96.7 236 271 327 319 141
1967 240 79.7 al5.7 13.9 16. I 15.5 13.0 83.9 290 271 334 432 lSI
1968 145 88.7 44.5 • .. • *
AVERAGE 228 110 49.7 27.3 22.6 22,9 27.0 92.3 243 306 307 281 143
PERCENT 13.3 6.4 2.9 1.6 1. 3 1.3 1.6 5,4 14.1 17.9 17.9 16.3 100
• No data for part or all of th• month. -llo data for part of the y .. r.
" Partly e•t1mnted. b Estimated. 21 c Corrected.
CONCLUSIONS
Water supply to the Snettisham hydroelectric project in southeast Alaska near
Juneau is assured in spite of glacier recession in the bas~_ns of Long and Crater
Lakes. Ablation of the glaciers during this century gave rise to speculation that
runoff would be significantly reduced as the glaciers became smaller. Comparative
studies of aerial photographs of the area spanning the p~riod 1929 to 1984 indicate
that glacier recession has been relatively minor. Estimates of ice-volume change
based on photogrammetric measurements indicate that less that 2. 5 percent of the
average runoff in the area has been contributed by loss of glaci~r-ice storage.
Analysis of streamflow records for the area shows that the quality and extent of
the data are sufficient to predict flow from the Crater Creek basin with a fairly
high degree of confidence.
REFERENCES CITED
Dort, J. C., 1924, Report to the Fecleral Power Commission on water powers of
Southeastern Alaska: Washington, Government Printing Office, 172 p.
Federal Power Commission and U.S. Forest Service, 194 7, Water powers Southeast
Alaska: Federal Power Commission P-9, 168 p.
Henshaw, F. F.~ 1933, Surface water supply of Southeastern Alaska, 1909-30: U.S.
Geological Survey Bulletin 836-C, p. 137-218.
Hutchinson, N. E., 1975, WATSTORE--National water data stora~e and retrieval system
of the U.S. Geological Survey--User's guide: U.S. Geological Survey Open-File
Report 75-426, 791 p.
Lamke, R. D., 1984, Cost-effectiveness of th~ stream-gaging program in Alaska:
U.S. Geological Survey Water-Resources Investigations Report 84-4096, 100 p.
Hayo, Larry R., 1984, Glad.er mass balance and runoff research in the U.S.A:
Geografiska Annaler, v. 66A, no. 3, p. 215-227.
U.S. Department of Agriculture, 1979, Water-resources atlas: Prepared by Forest
Service Region 10, Juneau, Alaska, 7 p.
U.S. Geological Survey, 1957, Compilat::!on of records of quantity and quality of
surface waters in Alaska through September 1950: U.S. Geological Survey
Water-Supply Paper 1372, 262 p.
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Areas or perennial snow and ice
delineated from aerial photography
obtained in the years shown.
0 1 2 MILES
1 2 KILOMETERS
PLATE 1.--Areas of perennial snow and ice in Crater Lake and Long Lake basins, Alaska.
-...