HomeMy WebLinkAbout3.7 TM001-Grant Creek Hydrologic Analysis-FinalTECHNICAL MEMORANDUM TM001
EMORANNO. 001
McMillen, LLC Page 1 Homer Electric Association, Inc.
May 30, 2014 Grant Lake Hydroelectric Project
To: Morton D. McMillen, P.E. Project: Grant Lake Hydroelectric Project
From: Andre Ball Cc: Cory Warnock
File
Date: May 30, 2014 Job No: 13-102
Subject: Grant Creek Hydrologic Analysis
1.0 INTRODUCTION
McMillen, LLC (McMillen) has been retained by Homer Electric Association, Inc. (HEA) to
provide engineering support for the proposed Grant Lake Hydroelectric Project (Project) FERC
application. The project would be located near the community of Moose Pass, Alaska,
approximately 25 miles north of Seward, Alaska.
1.1 Purpose and Scope
The purpose of this Technical Memorandum (TM) is to present the analyses and results of a
hydrologic analysis of the Grant Lake and Grant Creek basin. The analyses presented within this
TM utilized the available gage data, information from previous studies, as well as standard
hydrologic estimation techniques. The primary objectives of this TM are:
• Complete an independent review and analysis of previous hydrologic analyses completed for
the Grant Lake Basin;
• Assemble the available gage data for Grant Creek to support the analyses;
• Determine the peak streamflow magnitude and frequency discharges for Grant Creek that can
be used in the design of the Project;
• Complete a record extension for the Grant Creek streamflow gage record based on the USGS
Kenai River at Cooper Landing streamflow gage;
• Complete flow duration and mean daily flow analyses to be used in determining the
estimated Project energy production.
1.2 Project Description
As outlined in the application for a preliminary permit (HEA, 2011) the proposed Project
consists of constructing a new 5-Megawatt (approximate) hydroelectric facility on Grant Lake
and Grant Creek near Moose Pass, Alaska. The new Project would divert water from Grant Lake
and deliver the flow to a powerhouse located near the outlet of the existing Grant Creek natural,
incised rock canyon. The Project would include the following major components:
McMillen, LLC Page 2 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
• Diversion structure at the natural outlet of Grant Lake. (under consideration)
• An intake structure in Grant Lake.
• A tunnel extending from the lake intake to just east of the powerhouse.
• A powerhouse with two Francis turbines providing an anticipated combined 5-Megawatt
output. The maximum design flow will be approximately 385 cfs.
• Tailrace detention pond.
• Switchyard with disconnect switch and step-up transformer.
• An overhead or underground transmission line.
• A pole mounted disconnect switch where the transmission line intersects the main power
distribution line.
1.3 Project Background
Grant Lake has been studied on multiple occasions since the 1950’s as a potential hydropower
site. The previous work efforts included:
• 1954 – R.W. Beck and Associates preliminary investigation
• 1955 – U.S. Geological Survey (USGS) geological investigations of proposed power sites at
Cooper, Grant, Ptarmagin, and Crescent Lake
• 1980 – CH2M Hill prefeasibility study
• 1981 – U.S. Army Corps of Engineers (USACE) National Hydroelectric Power Resources
Study
• 1984 – Ebasco Services Project Feasibility Analysis (Ebasco, 1984)
• 2010 – HDR Grant Lake/Falls Creek Hydroelectric Project – Environmental Baseline Studies
(HDR, 2010)
On August 6, 2009, Kenai Hydro LLC filed a Pre-Application Document (PAD), along with a
Notice of Intent to file an application for an original license for the Grant Lake/Falls Creek
project. FERC subsequently approved the use of the Traditional License Process for
development of the license application and supporting documents. In 2009-2010, HDR
completed a series of environmental baseline studies which were summarized in their report
dated January 2010. A second preliminary permit was issued by FERC in 2012.
As part of these previous studies, the hydrologic conditions within the Grant Creek basin were
evaluated and flows available to support a hydroelectric facility were evaluated. The most
expansive analysis was completed as part of the Ebasco feasibility study. These previous studies
and available gage data were used as the basis for the current hydrologic analysis. The
subsequent gage data collected in 2009 (HDR, 2010) and 2013 by McMillen, along with the
original USGS stream gage data (USGS Station 15246000) served as the basis for the flow
estimation.
McMillen, LLC Page 3 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
1.4 Grant Creek Basin Description
Grant Lake and Grant Creek are located near Moose Pass, Alaska on the Kenai Peninsula (Figure
1). Grant Lake is an ‘L’-shaped, natural impoundment with a drainage area of 44.2 square miles
(Basin area shaded in Figure 1). The natural lake elevation is elevation 703 feet (NAVD88). The
lake has a surface area of 1,790 acres (2.8 square miles) and an active storage volume of 15,900
acre-feet between the lake elevations 703 feet and 692 feet. The mountains surrounding the basin
reach elevations of up to 5,900 feet, some of which have small glaciers on them. Inlet Creek is
the primary tributary and flows into the east end of Grant Lake. Several other small streams flow
into the lake from the steep valleys formed between the surrounding mountains.
Figure 1. Grant Lake Hydroelectric Project Location Map
Grant Creek is the only natural outlet from Grant Lake and is located at the south end of the lake.
Grant Creek is approximately 1 mile long and flows west from Grant Lake and discharges into
the Trail Lake Narrows that connects the Upper Trail Lake to Lower Trail Lake. The total drop
in elevation from Grant Lake to the Trail Lake Narrows is approximately 230 feet. The U.S.
Geological Survey (USGS) had previously operated a stream flow gage (Station 15246000) on
Grant Creek, but this gage is no longer operated. Additional basin statistics for Grant Creek are
provided in Table 1.
USGS Gage
15246000
Moose Pass
Grant Creek
Grant Lake
Grant Creek
Drainage Area
McMillen, LLC Page 4 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
Table 1. Grant Creek Basin Characteristics1
USGS
Station No. Station Name
Drainage
Area
(mi2)
Mean
Basin
Elevation
(ft)
Areas of
Lakes and
Ponds
(storage)
(percent)
Area of
Forest
(percent)
Mean Annual
Precipitation
(inches)
Mean Min.
January
Temperature
(°F)
15246000 Grant Creek near
Moose Pass, AK 44.2 2,900 10 20 90 10
1 Curran, Meyer, and Tasker, 2003
2.0 HYDROLOGIC DATA SUMMARY
The USGS operated streamflow gage 1524600 on Grant Creek between 1947 and 1958. Daily
and annual peak flows were recorded for this period. This 11-year record is the most complete
hydrologic data that exists for Grant Creek. The most recent statewide analysis of Alaska peak
streamflow frequency was completed in 2003 (Curran, Meyer, and Tasker, 2003). The basin
characteristics for Grant Creek in Table 1 are cited from this source.
2.1 Previous Hydrologic Studies
As discussed previously, Grant Lake has been studied several times since the 1950’s as a
potential hydroelectric project location. The most recent studies, which included hydrologic data,
are briefly described below. In 1981, the Alaska Power Authority (APA) authorized Ebasco
Services Inc. (Ebasco) to conduct a detailed feasibility analysis for Grant Lake and some
additional nearby basins. Intermittent streamflow data for Grant Creek was collected between
1981 and 1983; and was conducted by R&M Consultants (Ebasco, 1984). A HEC-4 Monthly
Streamflow Model was developed to extend the Grant Creek streamflow record and was used to
estimate power generation potential. The Ebasco study included a peak streamflow statistical
analysis and a Probable Maximum Flood (PMF) estimate (Table 2). In 2009, as part of the Grant
Creek Baseline Environmental Studies, HDR collected streamflow data between June and
October 2009 (HDR, 2010).
Table 2. Approximate Grant Creek Peak Streamflow Statistics from Ebasco Study1
Peak streamflow, in cubic feet per second (cfs), for a given recurrence interval in years
Q2 Q5 Q10 Q25 Q50 Q100 PMF
1,000 1,300 1,500 2,000 2,200 2,600 -- 27,700
1 Ebasco, 1984
2.2 Current Hydrologic Study
In 2013, under contract with HEA, McMillen reestablished streamflow measurements at the
former USGS gage location as part of an instream flow study. The streamflow measurement
location is referred to as GC200, consistent with the 2009 HDR report. McMillen established
continuous stage monitoring for Grant Creek at the beginning of April 2013 and stage
McMillen, LLC Page 5 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
monitoring is presently ongoing. The most recent streamflow data which has been retrieved and
gone through the QA/QC process is through December 2013. During spring and summer 2013,
five discharge measurements were taken for flows ranging between 17 and 706 cfs. These
measurements were used to develop a stage-discharge rating for the GC200 location.
3.0 HYDROLOGIC ANALYSIS
The ongoing hydrologic analysis of Grant Creek will be used as a foundation for determining the
anticipated power output from the powerhouse, determining the appropriate tailrace channel
elevation, and developing a tailwater rating curve for Grant Creek at the tailrace channel exit.
Flood protection requirements at the powerhouse site will be developed utilizing the peak
streamflow information. Detailed discussion of the analysis is presented in the following
paragraphs.
3.1 Peak Streamflow Magnitude and Frequency
3.1.1 Estimating Peak Streamflow Statistics Using Station Data
As stated previously, the 11-year USGS gage record for station 15246000 is the most complete
gage record for Grant Creek. This station data is the most suitable for a peak streamflow
magnitude and frequency analysis. The standard procedure for evaluating peak streamflow is to
utilize the log-Pearson Type III frequency distribution. This procedure is described in Bulletin
17B issued by the Interagency Advisory Committee on Water Data (IACWD, 1982). The
recommended minimum gage record length for such an analysis is 10 years. Additional
miscellaneous streamflow data was collected in the 1980’s, 2009, and 2013 by various
consulting firms. The 2013 and 1980’s data was excluded from the peak flow analysis since only
the partial year data were available at the time of this analysis. The 2009 data was excluded since
the stage-discharge information could not be verified. The peak streamflow estimates for Grant
Creek using station data are provided in Table 3.
3.1.2 Estimating Peak Streamflow Statistics Using Regional Regression Equations
Regional regression equations are often developed to estimate flow statistics for streams with no
gage record. Regional regression equations use basin characteristics (see Table 1 for basin data)
to estimate peak flow statistics. The most recent regional regression equations for basins in
Alaska were developed by the USGS in 2003 (Curran, Meyer, and Tasker, 2003). In the 2003
USGS study, Alaska was divided into 7 regions. Grant Creek is located in Region 4, which
includes the northern part of the Kenai and Alaska Peninsulas. Geographically, Grant Creek is
near the border of Region 3, which includes land along the Pacific Coast north of Juneau, along
the south side of the Kenai Peninsula, and the south side of the Aleutian Range. The peak
streamflow estimates for Grant Creek using the regional regression equation are provided in
Table 3.
McMillen, LLC Page 6 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
3.1.3 Grant Creek Peak Streamflow Magnitude and Frequency
Station and regression peak flow estimates may be combined to form a weighted value. This type
of estimate is especially useful for stations with a short record length, such as Grant Creek
(Curran, Meyer, and Tasker, 2003). Since Grant Creek had a suitable station record, it was
included in a table of station information and peak flow estimates in the 2003 USGS report. The
station, regression, and weighted peak flow estimates for Grant Creek from the 2003 report are
provided in Table 3. Flow magnitudes are provided for the 2-year through the 500-year
recurrence interval.
Table 3. Grant Creek Peak Streamflow Statistics at the USGS 15246000 Gage Location
Analysis Type Peak streamflow, in cubic feet per second (cfs), for a given recurrence interval in years
Q2 Q5 Q10 Q25 Q50 Q100 Q200 Q500
Station 936 1,330 1,660 2,170 2,620 3,140 3,760 4,730
Regression 1,260 1,810 2,220 2,760 3,170 3,590 4,020 4,620
Weighted 961 1,410 1,790 2,350 2,810 3,310 3,860 4,690
A weighted average adds in temporal variability from the longer gage records used to form the
regional regression. Most of the weighting goes to the local gage due to the uncertainty
introduced by the regional regression equations based on basin characteristics. The weighted
peak streamflow estimates for Grant Creek are considered to be the most appropriate and suitable
for use in the evaluation and design of the Grant Lake Hydroelectric Project moving forward.
3.2 Grant Creek Daily Streamflow Record Extension
In order to give a better long-term representation of the Grant Creek streamflows, a record
extension was conducted. A correlation between the Grant Creek USGS gage (station 15246000)
and the Kenai River at Cooper Landing USGS gage (station 15258000) provided a means to
extend the streamflow record at the Grant Creek gage location.
3.2.1 Record Extension Procedure
The procedure applied to Grant Creek was the “maintenance of variance extension” (MOVE),
specifically the MOVE1 procedure (Hirsch, 1982; Robison, 1991). The MOVE1 procedure
involves correlating short-term or incomplete gage data with one or more nearby gages that have
more complete records (long-term gage). These long-term values and the relationship between
the two gages are used to generate data to extend or fill in data at the short-term gage. Several
studies have compared the different procedures with varying results. Alley and Burns (1983)
illustrated several deficiencies of using simple linear regression including the loss of variance.
Hirsch (1982) and Robison (1991) both showed that MOVE1 was superior to regression or
regression plus noise when extending daily values.
McMillen, LLC Page 7 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
The MOVE1 record extension, as mentioned earlier, involves using a correlation relationship
between a “short-term” (incomplete or limited gage record) to a “long-term” (reference or source
gage). As record extension is done, the long-term and short-term gage data should come from
situations as similar as possible. Characteristics such as basin size, elevation, location, and other
basin characteristics should be as similar as possible. Ideally, both gages should be unregulated
or adjusted to unregulated conditions. In this study, extension occurs between mostly
unregulated gages. When extension occurs there is a concurrent record where the short-term
gage record and long-term record overlap. This concurrent record is used to create the
relationship to fill in missing data on the short-term gage to the period of record of the long-term
gage. The length of suitable concurrent record may be as small as 15–30 data points when the
points are independent and represent variable conditions. Generally, the longer the concurrent
record, the more confidence there is in the relationship.
By choosing gages with similar basin characteristics, there is a greater chance for a strong linear
predictive relationship between the short- and long-term gages. MOVE1 assumes a linear
relationship between the short- and long-term gages after they have been transformed into
logarithms (LOGS) of the flow values.
Synthetic discharge values for missing values from the short-term site are calculated by entering
known LOGs of the discharge at the long-term site into the equation (below) and then taking the
inverse (exponential) of the LOGS to get the short-term gage flows back into original units. The
equation for converting short-term gage flows in MOVE1 is show in Equation 1.
Equation 1 Yi = Yave+ YStndDev / XStndDev (Xi - Xave)
Where:
Yi = Short-term gage extended flow, at the ith step
Yave = Average (mean) of concurrent short-term gage data
YStndDev = Standard Deviation of concurrent short-term gage data
Xi = Long-term flow data at concurrent short-term data point, ith step
XStndDev = Standard Deviation of concurrent long-term gage data
Xave = Average of concurrent long-term gage data
3.2.2 Record Extension Application
The long-term gage selected for the Grant Creek record extension was the Kenai River at Cooper
Landing USGS gage (station 15258000). The Kenai River gage is located approximately 16
miles due west of the Grant Creek location and has a drainage area of 634 square miles. Grant
Creek is a tributary to the Kenai River. The period of record at the Kenai gage extends from
1947 to present and is concurrent with the entire 11-year period of record for the USGS Grant
Creek gage (1947-1958).
Figure 2 provides a graph of the log transformations of the concurrent streamflow data for Grant
Creek and Kenai River. The coefficient of determination (r2) of 0.92 represents an excellent
correlation between the two gages.
McMillen, LLC Page 8 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
Figure 2. Correlation of daily mean streamflow between Grant Creek and Kenai River
The concurrent period of record for the Grant Creek and Kenai River gages was used to develop
the MOVE1 equation. The MOVE1 equation was used to compute estimated Grant Creek
streamflow records, based on the Kenai River record, for the period May 1947 through
December 2013. The MOVE1 estimated streamflow record was combined with the observed
Grant Creek streamflows (from USGS, EBASCO, and McMillen records) to create a composite
record. The composite record (Composite) resulted in 66 complete years (Calendar Years 1948
through 2013) of streamflow for Grant Creek.
3.2.3 Cooper Lake Power Plant
The Kenai River flow at gage 15258000 is unregulated with the exception of the Cooper Lake
hydroelectric power plant. Chugach Electric Associations commissioned the Cooper Lake power
plant in 1960, which diverts flow from Cooper Lake into Kenai Lake, upstream of the 15258000
gage. Operations data from 1966-70 indicate that the average discharge from the Cooper Lake
power plant was 89 cfs (USGS 1976). During the same period, the average flow at the Kenai
gage was 2981 cfs, thus the additional inflow from Cooper Lake only represented about 3% of
the total flow. Absent of detailed operations records for the Cooper Lake power plant, no
adjustments to the Kenai gage record were made to account for this additional inflow. Thus, the
extended record streamflows for Grant Creek, after 1960, may be approximately 3% high.
y = 1.0172x - 1.2379
R² = 0.9233
1.0
1.5
2.0
2.5
3.0
3.5
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5LOG (streamflow, in cfs) Grant Creek LOG (streamflow, in cfs)
Kenai River at Cooper Landing
Concurrent daily-mean streamflow,
September 1947 through September 1958
McMillen, LLC Page 9 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
3.3 Streamflow Statistics
Streamflow statistics have been computed for Grant Creek to help characterize the daily
streamflow. A flow duration analysis and mean daily flow analysis was performed for both the
11-year USGS gage record, and the 66-year composite streamflow record for Grant Creek.
3.3.1 Flow Duration Analysis
A flow duration analysis evaluates the percentage of time that a given magnitude of flow is
exceeded. Flow duration curves were developed for the Grant Creek USGS record and
Composite record. Table 4 and Figure 3 display the daily flow duration results for Grant Creek.
With the exception of very high flows (<5% Days Exceeded), the USGS record was lower that
the composite record. For the median flow and below, the flow values for the USGS record were
between 29% and 41% lower than the longer Composite record. This indicates that the USGS
record represents a drier period of record.
Table 4. Grant Creek Daily Flow Duration Analysis
Percent of
Days Exceeded
Grant Creek Discharge
(cfs) [USGS Record,
WY 1948-1958]
Grant Creek Discharge
(cfs) [Composite Record,
CY 1948-2013]
11-year USGS Record
relative to 66-year
Composite Record
5% 580 575 1%
10% 496 499 -1%
20% 390 402 -3%
30% 279 302 -8%
40% 170 186 -9%
50% 91 110 -17%
60% 47 71 -34%
70% 33 49 -33%
80% 22 37 -41%
90% 18 27 -33%
95% 15 21 -29%
McMillen, LLC Page 10 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
Figure 3. Grant Creek Daily Flow Duration Analysis
3.3.2 Mean Daily Flow Analysis
A mean daily flow analysis evaluates the mean flow on a given day over multiple years of
recorded data. Averaging the daily flow values results in a composite, average annual
hydrograph where specific events are smoothed out but seasonal trends can be identified. Figure
4 compares the mean daily flow for the Grant Creek USGS Record and the Grant Creek
Composite record. The most recent annual hydrograph, from 2013, is also provided in Figure 4
for comparison. The figure presents the annual hydrograph with respect to the calendar year, as
opposed to a water year, due to the shape of the annual hydrograph.
The shape of the Grant Creek average annual hydrographs (USGS - dashed red line and
Composite - solid line) illustrate that annual runoff begins to increase in mid-April and peaks in
late June. The runoff declines from July through mid-November as the snowpack is diminished.
There is a slight bump between Mid-November and early December which is likely indicative of
late Fall rain-runoff events before the basin precipitation transitions to snow. There is also a
pronounced rise in the average annual hydrograph for the Composite record in the latter part of
September. This spike is a relic of the Kenai River gage data that was used to extend the Grant
Creek record. Almost a quarter of all Kenai River annual peak flows occurred in September and
a third of the September annual peaks were the result of glacial-outburst floods. Glacial-outburst
10
100
1000
10000
0%10%20%30%40%50%60%70%80%90%100%Discharge (cfs) Percent of Days Exceeded
Grant Creek [USGS Record, WY 1948-1958]
Grant Creek [Composite Record, CY 1948-2013]
McMillen, LLC Page 11 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
floods are events unique to a specific basin, in this case the Kenai basin, and thus, corresponding
glacial outbursts in the Grant Creek basin would not be expected. The MOVE1 record extension
method, described previously, is used to correlate the same types of runoff events between
basins, in this case, typically rainfall-runoff and snowmelt events.
The 2013 data (dashed blue line) shows that there were two peak runoff events, one in Mid-June
and one in Mid-September. The Mid-June event was a spring freshet with warming temperatures
resulting in increased snowmelt. The Mid-September event was a rainfall-runoff event resulting
from heavy precipitation. These two peaks do not imply that the most recent year contained more
intense run-off events. The average annual hydrographs are smoother due to averaging. The
shape and timing of the 2013 hydrograph is consistent average Grant Creek hydrographs.
Figure 4. Grant Creek Annual Hydrographs
4.0 CONCLUSIONS AND RECOMENDATIONS
4.1 Conclusions
The Grant Lake site has been studied on numerous occasions since 1954 when R.W. Beck
completed their original study. Within these studies, analyses of the hydrologic conditions within
0
200
400
600
800
1000
1200
1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/1 11/1 12/1Discharge (cfs) Date
Grant Creek Mean Daily Flow [USGS Record, WY 1948-1958]
Grant Creek Mean Daily Flow [Composite Record, CY 1948-2013]
2013 Grant Creek Mean Daily Flow [GC 200, McMillen]
McMillen, LLC Page 12 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
the basin were completed to develop an understanding of the potential water availability and
associated power production. The most comprehensive study was completed by Ebasco (Ebasco,
1984) which primarily utilized the 11-year gage record for USGS station 15246000 for their
analyses. The current study reviewed the more recent data collected in 2009 by HDR and 2013
data by McMillen. The USGS gage record for Grant Creek still represents the longest term and
most reliable streamflow data for Grant Creek.
Regional regression equations were used to improve the peak flow estimates. The estimated 100-
year discharge for Grant Creek was 3,310 cfs; the 25-year event was 2,350 cfs; and the 10-year
event was 1,790 cfs. In comparing these current flood magnitude estimates to the Ebasco
estimates, the smaller magnitude events are similar for both. The Ebasco 100-year estimate was
2,600 cfs, 700 cfs smaller than the present weighted estimate that included the regional
regression equations.
A daily streamflow record extension for Grant Creek was performed based on the Kenai River at
Cooper Landing USGS streamflow record. This record extension was used to create a
Composite, 66-year streamflow record for Grant Creek to be used for the Project. A flow
durational analysis of the Composite record indicated that the 95% exceedance flow was 21 cfs
and the 5% exceedance was 575 cfs. The 20% exceedance flow, which is often selected to size
powerhouse turbines, was estimated at 402 cfs. Additional streamflow data tables are provided in
Appendix A.
4.2 Recommendations
Based on the analysis presented in this TM, the estimated 100-year flood flow of 3,310 cfs is
recommended to be used to determine the flood protection requirements at the proposed
powerhouse. The Composite streamflow record for Grant Creek is recommended to be used as
the basis for developing energy production estimates from the generation model.
McMillen, LLC Page 13 Homer Electric Association, Inc.
May 30, 2014 Grant Creek Hydroelectric Project
5.0 REFERENCES
Alley, W.M. and A.W. Burns. 1983. Mixed-station extension of monthly streamflow records.
J. Hydraulic Eng. Vol. 109 (10). p. 1272- 1284.
Curran, J.H., Meyer, D.F., and Tasker, G.D., 2003. Estimating the magnitude and frequency of
peak streamflows for ungaged sites on streams in Alaska and conterminous basins in
Canada: U.S. Geological Survey Water-Resources Investigations Report 03-4188. [101 p.]
http://pubs.usgs.gov/wri/wri034188/
Ebasco, 1984. Grant Lake Hydroelectric Project Feasibility Analysis (Vo1umes 1 and 3).
Prepared for Alaska Power Authority.
HDR, 2010. Grant Lake/Falls Creek Hydroelectric Project – Environmental Baseline Studies,
2009 – Final Report. Prepared for Kenai Hydro, LLC.
Hirsch, R.M., 1982. A comparison of four streamflow record extension techniques. Water
Resources Research, v. 18, no. 4, p. 1081–1088.
Robison, E.G. 1991. Water availability for Oregon’s rivers and streams. Volume 2; Technical
Guide and Appendixes. Water Resources Department, Salem Oregon. May 1991.
U.S. Interagency Advisory Committee on Water Data (IAWCD). 1982. Guidelines for
determining flood flow frequency, Bulletin 17B of the Hydrology Subcommittee: Reston,
Virginia, U.S. Geological Survey, Office of Water Data Coordination [183 p.]
http://water.usgs.gov/osw/bulletin17b/bulletin_17B.html.
U.S. Geological Survey (USGS). 1976. Surface water supply of the United States, 1966-70, Part
15, Alaska. USGS Water Supply Paper: 2136
McMillen, LLC Homer Electric Association, Inc.
Grant Lake Hydroelectric Project
Appendix A: Gage Data
Grant Creek - USGS Station 15246000
Average of Daily Mean Discharges (cfs)
Data from Water Years 1948-1958
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 34 25 21 21 59 278 529 480 386 198 153 117
2 33 26 21 21 62 298 515 480 393 192 145 108
3 33 25 21 21 64 322 520 473 459 186 141 98
4 32 25 21 21 68 349 522 456 463 205 134 81
5 32 24 21 21 71 363 516 452 455 218 124 73
6 33 24 20 21 76 368 540 465 401 248 117 69
7 32 24 20 22 81 385 551 471 351 242 115 63
8 33 23 20 22 86 409 541 460 324 235 114 59
9 33 23 20 22 88 417 532 447 305 228 105 57
10 33 23 20 23 92 417 549 436 304 212 106 56
11 32 23 20 23 103 410 566 426 305 198 107 51
12 32 24 20 24 111 405 554 429 351 184 104 49
13 32 23 20 24 125 396 548 439 363 177 101 47
14 32 23 20 25 135 384 548 466 337 174 94 46
15 31 23 20 26 144 377 533 470 317 173 90 44
16 29 23 19 27 153 389 530 434 292 178 85 43
17 29 23 19 28 157 397 530 410 278 160 83 42
18 29 23 19 29 165 426 518 385 271 158 80 42
19 31 23 19 32 172 460 506 364 268 170 76 42
20 30 23 19 35 185 488 496 364 259 165 86 44
21 30 23 19 38 196 539 492 369 254 154 107 51
22 29 23 19 38 205 549 497 375 250 165 127 49
23 29 23 19 39 211 554 507 378 240 176 154 50
24 29 23 19 41 217 527 526 378 250 170 165 51
25 30 23 19 40 222 562 513 376 258 162 158 48
26 31 23 19 41 230 587 490 370 257 167 140 46
27 31 22 19 42 241 604 490 363 250 164 130 44
28 30 22 19 46 245 611 490 370 245 157 136 42
29 29 21 19 51 244 602 475 358 228 164 152 40
30 28 ---19 55 246 571 459 336 214 160 134 39
31 28 ---19 ---259 ---468 329 ---156 ---37
Mean 31 23 20 31 152 448 518 413 311 184 119 56
Min 28 21 19 21 59 278 459 329 214 154 76 37
Max 34 26 21 55 259 611 566 480 463 248 165 117
Grant Creek - Composite Record
(USGS Station 15246000 Location)
Average of Daily Mean Discharges (cfs)
Data from Calendar Years 1948-2013
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 57 47 37 30 58 290 489 489 392 281 170 102
2 56 47 37 30 61 300 488 487 383 284 164 101
3 56 47 36 30 65 309 488 484 386 282 163 100
4 55 46 36 30 68 319 488 484 382 282 158 96
5 54 47 36 30 72 328 489 484 374 278 153 92
6 54 47 35 30 76 336 496 485 365 282 150 88
7 53 47 35 30 80 347 505 482 358 284 148 84
8 53 46 34 30 84 360 508 476 350 281 145 80
9 52 46 34 30 88 371 510 470 344 275 139 78
10 52 45 34 31 93 379 514 469 341 272 137 76
11 51 45 34 31 99 386 517 469 339 273 133 74
12 50 44 33 31 105 391 518 467 344 270 128 72
13 50 44 33 32 113 393 519 464 348 267 123 71
14 50 43 33 32 121 394 520 466 349 260 120 69
15 50 42 33 33 129 397 515 466 350 249 117 69
16 50 42 32 33 137 406 511 455 356 236 117 68
17 51 41 32 34 143 417 509 447 362 223 114 67
18 51 41 32 34 150 432 506 435 373 212 108 66
19 53 40 32 35 158 444 502 427 386 204 103 65
20 53 40 32 36 166 454 500 423 399 196 101 65
21 53 40 32 38 173 464 499 420 413 188 102 66
22 53 39 31 39 181 467 500 420 418 187 103 66
23 53 39 31 40 189 469 501 417 412 191 108 65
24 53 39 31 41 199 466 504 412 398 194 110 65
25 53 39 31 42 208 474 503 407 385 193 107 64
26 53 38 31 44 218 481 498 403 366 190 103 63
27 53 38 30 46 230 488 497 400 348 184 100 62
28 52 38 30 49 241 494 495 396 333 178 101 61
29 51 37 30 52 251 497 492 390 315 179 103 60
30 49 ---30 55 263 494 489 384 298 178 103 59
31 49 ---30 ---277 ---489 385 ---177 ---58
Mean 52 43 33 36 145 408 502 444 366 233 124 73
Min 49 37 30 30 58 290 488 384 298 177 100 58
Max 57 47 37 55 277 497 520 489 418 284 170 102
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1947
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 ---------------------------418 152 500
2 ---------------------------467 131 480
3 ---------------------------404 117 400
4 ---------------------------362 104 250
5 ---------------------------327 91 180
6 ---------------------------313 78 160
7 ---------------------------306 86 130
8 ---------------------------278 86 110
9 ---------------------------250 84 100
10 ---------------------------222 82 94
11 ---------------------------243 78 86
12 ---------------------------236 72 76
13 ---------------------------229 68 71
14 ---------------------------236 66 65
15 ---------------------------236 64 65
16 ---------------------------222 64 58
17 ---------------------------208 62 52
18 ---------------------------180 62 47
19 ---------------------------159 64 47
20 ---------------------------145 70 71
21 ---------------------------138 80 65
22 ---------------------------215 230 58
23 ---------------------------320 420 71
24 ---------------------------313 500 71
25 ---------------------------278 540 52
26 ---------------------------280 430 52
27 ---------------------------278 350 42
28 ---------------------------243 460 42
29 ---------------------------243 700 38
30 ---------------------------201 600 35
31 ---------------------------187 ---35
Mean ---------------------------262 200 116
Min ---------------------------138 62 35
Max ---------------------------467 700 500
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1948
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 33 30 18 16 32 383 529 467 173 138 128 39
2 30 42 19 15 38 376 561 453 160 138 128 36
3 30 38 18 15 42 348 569 432 152 173 120 33
4 26 32 18 14 52 362 585 418 152 173 120 31
5 25 28 18 14 58 369 585 418 160 152 107 29
6 27 27 17 14 78 362 765 432 166 138 100 28
7 26 26 17 14 84 369 780 418 180 117 128 27
8 24 25 17 15 104 369 705 383 208 320 120 27
9 23 24 17 16 104 383 665 355 222 517 81 28
10 22 25 16 16 104 390 665 334 236 537 100 29
11 23 26 16 19 173 411 625 316 222 478 148 28
12 28 26 16 21 187 425 585 320 210 436 148 28
13 30 24 16 23 208 482 521 348 201 358 142 29
14 30 23 16 28 229 553 529 453 180 324 128 28
15 28 22 16 35 264 585 521 505 194 316 114 27
16 28 22 16 42 313 625 561 545 210 400 107 26
17 30 21 16 42 320 609 545 545 220 372 94 27
18 32 21 16 42 383 665 561 505 208 352 87 27
19 32 20 16 47 369 705 545 467 201 324 74 26
20 30 20 16 42 348 665 529 425 180 324 62 27
21 32 20 15 38 341 600 497 397 145 260 55 24
22 30 20 15 35 313 561 490 418 138 226 50 23
23 28 19 15 35 306 537 497 453 117 212 48 22
24 30 19 15 35 292 505 529 418 104 198 45 21
25 42 20 16 32 320 505 521 348 104 176 43 21
26 58 21 17 30 390 529 505 299 91 162 46 20
27 58 20 18 30 446 545 497 257 78 148 45 19
28 52 19 17 28 460 529 475 230 65 156 43 18
29 44 19 16 30 425 505 446 210 71 148 42 18
30 38 ---15 30 404 529 418 194 117 142 40 18
31 35 ---16 ---390 ---432 180 ---128 ---18
Mean 32 24 16 27 244 493 556 385 162 259 90 26
Min 22 19 15 14 32 348 418 180 65 117 40 18
Max 58 42 19 47 460 705 780 545 236 537 148 39
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1949
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 18 13 14 16 25 450 380 390 660 420 215 150
2 19 12 13 16 22 467 380 400 710 370 208 146
3 20 11 14 14 20 467 376 370 770 330 220 140
4 20 12 15 13 20 450 411 370 800 300 180 130
5 19 13 16 14 20 430 470 380 800 270 160 120
6 17 13 15 14 20 380 540 390 740 250 170 115
7 16 12 16 14 19 350 580 411 610 250 145 100
8 16 11 14 13 19 330 590 430 550 210 138 91
9 17 11 14 13 18 320 570 440 470 190 120 82
10 18 11 13 14 19 310 545 430 410 170 110 76
11 17 12 14 14 20 310 530 410 370 150 100 68
12 16 13 16 14 20 320 540 360 320 140 92 60
13 15 14 16 14 21 340 577 320 300 150 95 58
14 15 14 15 14 23 334 560 274 290 140 91 55
15 14 13 14 14 25 320 540 260 320 130 84 53
16 14 12 13 15 27 310 510 230 310 110 77 55
17 13 11 12 16 30 310 490 210 300 98 74 54
18 12 11 12 17 38 330 480 200 285 90 74 54
19 13 11 13 18 58 369 480 200 260 95 81 55
20 13 11 13 20 91 400 460 208 250 110 180 54
21 13 11 14 20 110 450 430 218 230 100 397 53
22 13 12 15 18 222 600 400 280 220 90 500 50
23 13 13 17 16 278 785 400 260 210 80 545 48
24 14 13 17 18 313 600 432 240 250 84 467 46
25 13 14 17 19 320 500 440 230 330 159 334 45
26 12 14 17 19 341 430 460 230 430 264 250 44
27 13 14 16 23 418 397 460 240 520 299 230 43
28 13 14 15 27 430 390 460 300 630 260 215 42
29 12 ---16 30 432 430 430 360 550 243 190 41
30 13 ---16 27 410 390 400 480 470 243 159 41
31 13 ---16 ---430 ---376 560 ---222 ---41
Mean 15 12 15 17 137 409 474 325 446 194 197 71
Min 12 11 12 13 18 310 376 200 210 80 74 41
Max 20 14 17 30 432 785 590 560 800 420 545 150
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1950
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 43 27 20 17 39 200 545 397 327 166 54 21
2 43 27 20 17 39 210 529 390 320 160 50 21
3 43 27 20 17 39 210 545 390 300 170 47 21
4 43 27 20 17 39 220 505 432 290 173 43 21
5 43 27 20 16 42 230 497 460 264 166 42 21
6 40 22 19 16 47 280 490 482 260 150 41 21
7 40 22 19 16 44 292 510 480 250 139 39 21
8 40 22 19 16 55 300 510 467 257 133 36 21
9 40 22 19 16 61 290 545 450 280 120 35 21
10 40 22 19 17 77 250 565 440 370 110 34 21
11 37 20 18 18 100 383 600 450 450 110 33 21
12 37 20 18 19 110 320 585 467 486 110 33 21
13 37 20 18 20 120 240 570 482 440 105 35 21
14 37 20 18 22 139 240 545 480 370 100 28 21
15 37 20 18 23 140 250 505 520 360 95 28 21
16 38 19 18 23 140 310 486 505 350 89 28 21
17 38 19 18 25 140 420 470 490 348 81 28 21
18 38 19 18 29 140 540 440 460 360 77 28 21
19 38 19 18 32 140 650 400 453 390 74 28 21
20 38 19 18 35 139 750 400 467 430 70 28 21
21 33 19 18 37 139 865 450 480 505 67 28 21
22 33 19 18 39 140 820 525 505 470 64 28 21
23 33 19 18 42 152 800 665 540 420 67 28 21
24 33 19 18 39 160 665 849 569 369 77 28 21
25 33 19 18 35 170 665 700 640 320 76 28 21
26 33 19 17 34 170 580 505 650 280 74 28 21
27 33 19 17 34 173 570 480 600 250 70 28 21
28 33 19 17 35 173 570 460 529 220 67 28 21
29 33 ---17 37 180 610 440 490 200 64 28 21
30 33 ---17 39 194 665 420 400 190 62 28 21
31 33 ---17 ---200 ---400 340 ---58 ---21
Mean 37 21 18 26 117 447 521 481 338 101 33 21
Min 33 19 17 16 39 200 400 340 190 58 28 21
Max 43 27 20 42 200 865 849 650 505 173 54 21
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1951
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 21 16 13 17 45 190 467 340 530 120 60 33
2 21 16 13 21 45 220 500 340 530 120 60 33
3 21 16 13 21 45 257 545 340 530 120 60 33
4 21 16 13 21 45 360 545 340 530 120 60 33
5 21 16 13 21 45 360 486 362 530 120 60 33
6 21 16 13 21 48 360 540 390 530 120 60 33
7 21 16 13 21 84 360 620 390 530 120 60 33
8 21 16 13 21 84 360 665 390 530 120 60 33
9 21 16 13 21 84 360 660 390 530 120 60 33
10 21 16 13 21 84 450 660 390 530 120 60 33
11 21 16 13 21 84 330 660 390 530 120 60 33
12 21 16 13 21 84 330 660 414 530 120 60 33
13 21 16 13 21 135 330 660 470 530 120 60 33
14 21 16 13 21 170 330 660 560 530 120 60 33
15 21 16 13 23 170 330 585 545 530 120 60 31
16 17 15 14 25 170 330 540 420 480 120 43 28
17 17 15 14 25 170 257 540 420 480 60 43 28
18 17 15 14 25 170 230 540 420 480 53 43 28
19 17 15 14 25 170 230 540 344 480 53 43 28
20 17 15 14 25 170 230 540 310 480 53 43 28
21 17 15 14 25 170 230 540 310 480 53 43 28
22 17 15 14 25 170 230 467 310 480 53 43 28
23 17 15 14 31 170 230 400 310 480 53 43 28
24 17 15 14 43 170 348 400 310 480 53 43 28
25 17 15 14 43 170 420 400 292 480 53 43 28
26 17 15 14 43 170 420 400 360 480 53 43 28
27 17 15 14 43 140 420 400 360 480 53 43 28
28 17 15 14 43 140 420 400 360 480 53 43 28
29 17 ---14 43 140 420 362 360 480 53 43 28
30 19 ---16 43 152 420 350 360 480 53 43 28
31 19 ---16 ---160 ---340 360 ---53 ---28
Mean 19 16 14 27 124 325 518 376 505 88 52 30
Min 17 15 13 17 45 190 340 292 480 53 43 28
Max 21 16 16 43 170 450 665 560 530 120 60 33
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1952
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 20 16 17 14 17 200 510 555 306 279 300 168
2 20 16 17 14 18 212 452 508 306 251 283 110
3 20 16 17 14 19 212 466 476 292 276 270 110
4 20 16 17 14 20 210 423 472 276 560 254 110
5 20 16 17 14 22 212 435 476 254 702 244 110
6 20 16 17 14 23 200 510 494 222 708 225 110
7 20 16 17 14 25 184 585 570 202 605 247 110
8 20 16 17 14 27 176 533 600 188 512 300 110
9 20 16 17 14 30 176 479 580 175 440 300 110
10 20 16 17 14 33 200 456 555 163 408 328 110
11 20 16 17 14 38 218 470 526 156 376 338 90
12 20 16 15 14 42 282 533 565 152 338 328 90
13 20 16 15 14 44 344 651 570 163 317 303 90
14 20 16 15 14 45 358 675 540 213 324 273 90
15 20 16 15 14 45 358 603 521 244 331 263 90
16 17 17 15 15 47 390 528 472 241 331 241 90
17 17 17 15 15 51 414 479 420 225 300 213 90
18 17 17 15 15 56 450 452 380 208 279 193 90
19 17 17 15 15 60 464 443 338 193 260 175 90
20 17 17 15 15 74 471 484 346 188 244 178 90
21 17 17 15 15 90 521 538 349 222 228 178 186
22 17 17 15 15 90 541 669 349 314 219 165 178
23 17 17 15 15 90 565 733 346 349 208 235 186
24 17 17 15 15 92 537 792 328 400 193 372 202
25 17 17 15 15 95 509 785 328 462 183 372 196
26 17 17 15 15 100 494 720 324 458 202 335 180
27 17 17 15 15 111 545 702 314 420 228 286 161
28 17 17 15 15 130 621 696 292 384 247 260 147
29 17 17 15 15 156 601 702 286 349 306 228 135
30 17 ---15 15 170 581 636 283 306 300 196 122
31 17 ---15 ---190 ---595 289 ---289 ---106
Mean 18 16 16 15 66 375 572 434 268 337 263 124
Min 17 16 15 14 17 176 423 283 152 183 165 90
Max 20 17 17 15 190 621 792 600 462 708 372 202
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1953
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 90 42 33 24 170 524 1210 657 352 115 80 45
2 83 42 33 24 177 575 989 831 320 108 80 44
3 76 42 33 24 182 657 885 933 295 103 80 44
4 72 42 33 24 193 726 810 831 391 126 80 42
5 70 42 33 24 201 768 747 675 549 237 80 41
6 70 42 33 24 204 726 705 585 538 645 80 40
7 64 42 33 24 207 699 693 569 488 740 80 38
8 64 42 33 24 207 705 699 538 443 657 80 39
9 64 42 33 24 201 733 651 538 387 528 80 41
10 64 42 33 24 190 761 609 549 345 423 80 41
11 64 42 33 24 177 719 597 520 305 367 74 41
12 64 42 33 24 198 699 627 484 302 323 74 39
13 64 42 33 24 212 663 657 524 327 363 74 38
14 64 42 33 24 243 597 719 585 338 356 74 38
15 64 42 33 24 262 554 754 549 331 313 74 37
16 47 48 28 26 278 543 761 488 309 281 74 40
17 47 48 28 30 302 543 719 427 288 243 74 41
18 47 48 28 35 323 564 675 391 269 218 74 41
19 47 48 28 66 359 621 663 367 246 204 74 39
20 47 48 28 90 399 663 621 349 230 185 74 39
21 47 48 28 110 411 733 575 341 210 167 59 41
22 47 48 28 120 387 824 559 349 193 165 56 40
23 47 48 28 120 359 925 575 407 195 160 58 40
24 47 48 28 120 345 1050 580 439 201 150 56 42
25 47 48 28 115 338 1510 705 448 193 140 54 41
26 47 46 28 110 331 1920 754 419 177 130 53 39
27 47 45 28 109 338 2090 754 387 165 120 51 39
28 47 44 28 126 356 2140 747 439 154 110 50 37
29 47 ---28 145 356 2010 705 474 139 100 48 36
30 47 ---28 160 367 1610 663 427 126 99 47 35
31 47 ---28 ---439 ---645 387 ---97 ---34
Mean 58 44 30 61 281 928 711 513 294 257 69 40
Min 47 42 28 24 170 524 559 341 126 97 47 34
Max 90 48 33 160 439 2140 1210 933 549 740 80 45
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1954
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 34 32 32 25 55 233 452 627 237 160 338 93
2 33 32 32 25 56 269 452 569 227 158 327 86
3 32 32 32 25 58 313 427 543 233 147 309 79
4 30 32 32 25 63 327 411 520 240 135 285 71
5 30 32 32 25 68 352 395 484 237 124 253 65
6 30 32 32 25 80 387 379 466 224 115 224 60
7 30 32 32 25 89 431 367 456 215 110 198 57
8 33 32 32 25 94 492 379 439 201 98 177 57
9 40 32 32 25 106 510 399 439 193 96 154 58
10 40 32 32 25 117 502 448 427 221 94 137 56
11 38 34 32 25 131 479 502 431 230 91 122 52
12 38 34 32 25 156 484 492 448 221 89 112 51
13 37 34 32 25 180 448 456 403 198 86 106 50
14 36 34 32 25 182 383 423 352 177 96 97 48
15 35 34 32 25 180 367 419 323 167 154 91 45
16 35 34 25 25 185 363 452 305 172 180 89 44
17 34 34 25 25 190 375 474 281 224 170 84 43
18 34 34 25 25 190 403 452 295 249 154 82 44
19 32 34 25 25 201 427 448 320 249 147 78 50
20 32 34 25 25 221 431 443 338 230 143 78 50
21 31 34 25 29 230 452 423 323 207 126 76 46
22 31 34 25 30 224 435 391 298 182 119 76 45
23 30 34 25 31 233 403 363 320 163 239 86 42
24 29 34 25 33 262 387 345 356 185 302 96 39
25 29 34 25 36 275 403 327 363 185 281 124 38
26 28 34 25 39 272 435 331 352 170 295 126 38
27 28 34 25 44 275 452 352 331 154 272 122 37
28 27 34 25 47 265 452 387 298 139 246 115 37
29 27 ---25 50 256 448 411 278 145 237 104 37
30 26 ---25 53 237 439 456 262 151 243 97 37
31 26 ---25 ---224 ---549 249 ---309 ---37
Mean 32 33 28 30 173 409 420 384 201 168 145 51
Min 26 32 25 25 55 233 327 249 139 86 76 37
Max 40 34 32 53 275 510 549 627 249 309 338 93
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1955
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 38 27 18 18 20 112 403 627 768 95 59 25
2 38 27 18 18 21 112 461 621 810 91 56 25
3 38 27 18 18 22 114 559 597 621 89 53 25
4 38 27 18 18 23 117 693 559 488 88 51 25
5 38 27 18 18 24 122 693 675 391 93 48 25
6 38 27 18 18 26 127 651 789 331 96 47 25
7 38 27 18 18 26 135 627 726 285 93 47 25
8 38 27 18 18 28 156 609 633 249 89 45 25
9 38 27 18 18 29 210 657 543 237 85 44 25
10 38 27 18 18 32 240 877 497 265 81 44 25
11 38 27 18 18 38 278 1030 456 302 77 44 25
12 38 27 18 18 44 275 893 411 379 75 43 25
13 38 27 18 18 53 259 733 371 375 71 42 25
14 38 27 18 18 56 240 633 345 334 74 42 25
15 38 27 18 18 61 230 575 313 288 71 43 25
16 45 20 18 18 76 240 559 275 249 71 42 25
17 45 20 18 18 90 262 528 253 210 74 42 25
18 45 20 18 18 98 316 510 237 180 76 41 25
19 45 20 18 18 100 383 520 230 163 74 41 25
20 45 20 18 18 102 415 575 227 143 69 40 25
21 45 20 18 18 103 423 657 227 131 68 39 25
22 45 20 18 18 103 431 712 233 126 85 38 25
23 45 20 18 18 106 443 740 246 117 99 37 25
24 45 20 18 18 119 456 726 295 117 99 36 25
25 45 20 18 18 126 488 687 352 115 94 35 25
26 45 20 18 18 124 488 663 349 112 88 34 25
27 45 20 18 18 119 448 633 338 108 84 33 25
28 45 20 18 18 117 423 591 334 104 78 32 25
29 45 ---18 18 117 395 569 298 98 72 31 25
30 45 ---18 18 117 383 564 259 94 65 30 25
31 45 ---18 ---112 ---609 308 ---63 ---25
Mean 42 24 18 18 72 291 643 407 273 82 42 25
Min 38 20 18 18 20 112 403 227 94 63 30 25
Max 45 27 18 18 126 488 1030 789 810 99 59 25
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1956
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 20 17 15 18 74 141 456 534 312 94 44 119
2 20 17 15 18 78 139 460 477 290 91 45 108
3 20 17 15 18 79 145 460 431 263 88 44 98
4 20 17 15 18 78 154 460 390 245 87 44 89
5 20 17 15 18 81 156 452 358 231 84 43 83
6 20 17 15 18 87 166 447 397 220 79 42 76
7 20 17 15 18 89 178 460 447 212 75 41 71
8 20 17 15 18 91 199 469 443 202 71 41 65
9 20 17 15 18 95 215 439 416 193 69 42 60
10 20 17 15 18 95 228 408 408 193 69 41 58
11 20 17 15 18 94 237 393 424 215 70 41 54
12 20 17 15 18 93 251 397 460 245 69 41 51
13 20 17 15 18 90 263 443 469 284 67 41 49
14 20 17 15 18 89 278 505 456 296 66 41 46
15 20 17 15 18 87 293 576 486 272 64 40 44
16 20 17 15 18 87 318 622 560 248 65 39 41
17 20 17 15 18 88 355 633 560 223 63 38 39
18 20 17 15 18 89 372 610 545 248 62 38 37
19 20 17 15 18 90 368 571 555 281 60 38 36
20 20 17 15 18 105 355 539 645 272 59 38 35
21 20 17 15 21 147 332 500 599 239 57 41 34
22 20 17 15 20 183 305 473 510 210 54 44 34
23 20 17 15 20 196 290 447 452 183 51 43 33
24 20 17 15 21 193 290 435 397 160 49 42 32
25 20 17 15 22 191 287 416 386 141 49 47 32
26 20 17 15 26 199 299 400 375 129 48 70 31
27 20 17 15 29 196 322 404 368 119 52 130 31
28 20 17 15 35 191 332 404 412 112 51 145 30
29 20 17 15 46 183 372 404 397 105 49 151 30
30 20 ---15 58 160 427 424 355 99 47 134 30
31 20 ---15 ---147 ---500 335 ---45 ---29
Mean 20 17 15 22 121 269 471 453 215 65 56 52
Min 20 17 15 18 74 139 393 335 99 45 38 29
Max 20 17 15 58 199 427 633 645 312 94 151 119
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1957
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 26 19 20 19 46 288 423 327 363 175 253 98
2 26 19 20 19 46 327 431 327 435 156 230 104
3 26 19 20 19 49 407 427 327 1390 143 227 100
4 26 19 20 20 52 492 423 327 1500 129 253 94
5 26 19 20 20 55 543 399 305 1410 119 240 94
6 26 19 20 20 60 569 363 288 1000 110 215 89
7 26 19 20 20 66 627 341 291 712 104 193 82
8 26 19 20 20 80 687 334 320 564 100 172 76
9 26 19 20 20 100 687 352 352 502 96 158 70
10 26 19 20 20 115 651 383 371 452 93 147 68
11 26 19 21 20 135 585 403 375 419 91 141 61
12 26 19 21 20 149 549 403 363 853 86 143 60
13 26 19 21 21 172 488 399 331 1020 82 143 55
14 26 19 21 23 167 479 407 320 817 79 135 52
15 26 19 21 25 204 466 423 338 621 76 124 49
16 19 19 21 25 210 448 423 356 488 90 127 47
17 19 19 21 26 195 423 419 367 399 96 163 45
18 19 19 21 27 190 415 403 349 359 196 156 44
19 19 19 21 28 204 403 383 323 345 423 143 42
20 19 19 21 30 237 391 341 305 309 411 160 40
21 19 19 18 36 259 359 316 423 295 427 185 39
22 19 19 18 38 253 352 305 466 298 520 172 37
23 19 19 18 40 240 345 285 427 275 448 154 36
24 19 19 18 43 227 341 272 387 334 356 135 35
25 19 19 18 44 218 345 275 356 371 295 120 34
26 19 19 18 45 212 345 291 349 363 243 120 33
27 19 19 18 45 218 345 295 474 323 201 112 33
28 19 19 18 45 221 349 285 575 281 218 108 32
29 19 ---18 45 230 367 291 520 243 288 104 32
30 19 ---18 45 253 399 305 435 207 302 102 32
31 19 ---18 ---269 ---316 383 ---262 ---32
Mean 22 19 20 29 166 449 359 370 565 207 161 56
Min 19 19 18 19 46 288 272 288 207 76 102 32
Max 26 19 21 45 269 687 431 575 1500 520 253 104
Grant Creek - USGS Station 15246000
Daily Mean Discharge (cfs)
Calendar Year
1958
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 32 32 27 44 125 335 447 361 220 ---------
2 32 32 27 48 139 372 447 361 212 ---------
3 33 32 27 49 154 408 464 368 199 ---------
4 35 31 26 50 162 424 477 361 186 ---------
5 40 30 26 50 164 447 520 379 178 ---------
6 49 30 25 52 162 491 545 404 176 ---------
7 56 30 25 55 158 610 496 424 178 ---------
8 62 30 26 59 154 726 456 420 174 ---------
9 58 29 25 60 145 705 431 416 169 ---------
10 54 29 25 62 141 610 424 393 160 ---------
11 51 29 25 65 139 555 416 390 158 ---------
12 48 29 24 66 141 515 382 431 160 ---------
13 45 28 24 67 143 496 365 539 160 ---------
14 43 29 25 69 143 431 368 761 158 ---------
15 41 28 25 68 143 390 358 810 156 ---------
16 38 28 25 68 145 397 393 616 151 ---------
17 36 28 25 67 147 404 529 539 145 ---------
18 42 30 25 67 143 404 576 456 139 ---------
19 58 30 25 65 141 443 571 408 138 ---------
20 56 29 25 66 145 599 520 382 132 ---------
21 53 28 25 65 156 965 486 390 125 ---------
22 51 28 25 65 169 941 473 404 120 ---------
23 49 28 25 64 186 768 469 393 134 ---------
24 44 28 25 64 210 622 424 416 147 ---------
25 43 27 26 65 215 555 382 397 141 ---------
26 40 27 25 69 223 520 361 365 138 ---------
27 39 27 25 77 218 505 408 328 134 ---------
28 38 28 26 87 212 491 486 296 129 ---------
29 35 ---26 101 212 469 469 269 123 ---------
30 34 ---27 114 242 443 408 245 115 ---------
31 33 ---29 ---290 ---382 231 ------------
Mean 44 29 26 66 170 535 449 418 155 ---------
Min 32 27 24 44 125 335 358 231 115 ---------
Max 62 32 29 114 290 965 576 810 220 ---------
Grant Creek - EBASCO Gage
Daily Mean Discharge (cfs)
Calendar Year
1981
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 ------------------------------------
2 ------------------------------------
3 ------------------------------------
4 ------------------------------------
5 ------------------------------------
6 ------------------------------------
7 ------------------------------------
8 ------------------------------------
9 ------------------------------------
10 ------------------------------------
11 ------------------------------------
12 ------------------------------------
13 ------------------------------------
14 ------------------------------------
15 ------------------------------------
16 ------------------------------------
17 ------------------------------------
18 ------------------------------------
19 ------------------------------------
20 ------------------------------------
21 ---------------------------121 ------
22 ------------------------------------
23 ------------------------------------
24 ------------------------------------
25 ------------------------------------
26 ------------------------------------
27 ------------------------------------
28 ------------------------------------
29 ------------------------------------
30 ------------------------------------
31 ------------------------------------
Mean ------------------------------------
Min ---------------------------121 ------
Max ---------------------------121 ------
Grant Creek - EBASCO Gage
Daily Mean Discharge (cfs)
Calendar Year
1982
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 ---------26 ---196 468 490 284 260 103 94
2 ---------------210 446 472 262 ---104 92
3 ---------------223 400 460 232 ---101 94
4 ------30 ------234 365 449 261 ---105 97
5 ---------------238 365 434 219 ---105 108
6 ---------------244 354 427 412 ---103 120
7 ---------------262 361 427 454 ---101 118
8 ---------------274 408 438 451 ---101 111
9 43 ------------298 442 442 446 ---99 108
10 ---------------342 488 434 424 ---97 108
11 ---------------394 486 419 407 ---94 104
12 ---------------375 472 405 385 ---92 101
13 ---------------348 466 393 394 ---92 96
14 ---------------314 472 400 433 ---91 92
15 ---------------290 474 400 457 ---90 90
16 ---------------274 474 398 602 ---89 89
17 ---------------304 472 374 590 ---87 96
18 ---------------304 466 358 552 ---86 104
19 ---------------274 460 338 545 ---84 110
20 ---------------282 464 316 532 ---84 108
21 ------------97 282 472 305 514 ---77 106
22 ---------------278 476 289 504 ---77 104
23 ---------------276 474 296 482 ---76 103
24 ------------150 288 486 307 454 ---76 101
25 ------------155 306 486 316 433 ---80 97
26 ------------166 338 474 303 407 ---89 96
27 ------------170 388 472 294 383 ---101 95
28 ------------166 460 474 274 347 105 101 94
29 ------------166 482 490 280 290 104 99 93
30 22 ---------170 468 514 298 260 103 96 92
31 ------------180 ---505 292 ---101 ---91
Mean ---------------308 456 372 414 ---93 100
Min 22 ---30 26 97 196 354 274 219 101 76 89
Max 43 ---30 26 180 482 514 490 602 260 105 120
Grant Creek - EBASCO Gage
Daily Mean Discharge (cfs)
Calendar Year
1983
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 ------------96 512 535 422 303 136 110 138
2 ------------107 517 533 424 297 135 113 141
3 ------------114 496 517 429 282 133 117 140
4 ------------119 466 507 449 261 130 114 133
5 ------------119 432 509 456 229 127 113 128
6 ------------120 412 504 476 203 122 111 122
7 ------------117 412 499 476 182 117 111 116
8 ------------119 419 494 489 174 114 113 ---
9 ------------123 422 522 494 167 113 113 ---
10 ------------128 439 530 481 160 117 124 ---
11 ------------130 439 517 461 156 131 128 ---
12 ------------133 429 501 444 149 139 128 ---
13 ------------138 424 491 427 146 139 124 ---
14 ------------146 429 489 405 165 136 119 ---
15 ------------156 436 486 382 148 133 117 ---
16 ------------166 432 484 368 143 130 113 ---
17 ------------175 432 486 354 138 127 111 ---
18 ------------184 434 486 345 133 128 105 ---
19 ------------184 449 479 336 136 128 102 ---
20 ------------182 459 469 327 144 123 98 ---
21 46 ---------184 456 459 323 154 127 95 ---
22 ------------193 459 449 327 161 133 94 ---
23 ------18 ---199 466 434 325 158 135 92 ---
24 ------------197 476 424 323 153 133 89 ---
25 ------------195 489 417 318 146 128 88 ---
26 ---------65 195 507 407 320 143 123 87 ---
27 ---------70 195 519 410 323 138 120 84 ---
28 ---------80 195 525 419 323 135 122 88 ---
29 ---------87 208 525 432 320 136 119 96 ---
30 ---------92 288 530 434 318 138 116 128 ---
31 ---------96 424 ---429 310 ---113 ------
Mean ------------169 461 476 386 173 127 108 ---
Min 46 ---18 65 96 412 407 310 133 113 84 116
Max 46 ---18 96 424 530 535 494 303 139 128 141
Grant Creek - McMillen GC200 Gage
Daily Mean Discharge (cfs)
Calendar Year
2013
Day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 ------------28 565 616 459 348 224 370 60
2 ------------31 554 600 448 335 207 321 59
3 ---------19 33 545 539 436 362 204 280 57
4 ---------19 41 507 468 420 411 216 250 56
5 ---------19 46 472 436 381 411 212 229 56
6 ---------19 49 446 433 368 396 200 208 56
7 ---------19 52 440 460 367 443 190 188 54
8 ---------19 56 477 486 381 438 186 174 54
9 ---------19 60 542 453 402 427 190 157 53
10 ---------19 65 613 432 432 483 183 156 52
11 ---------19 75 659 438 459 636 175 154 50
12 ---------18 94 710 441 521 665 169 137 49
13 ---------18 125 734 444 484 604 284 125 49
14 ---------18 154 712 452 434 520 392 118 52
15 ---------17 162 718 451 390 445 359 110 53
16 ---------17 158 784 454 359 386 329 102 51
17 ---------16 151 862 466 348 333 317 94 49
18 ---------17 143 970 493 336 298 311 87 49
19 ---------16 130 1005 521 319 264 313 82 49
20 ---------17 130 960 526 317 230 315 77 48
21 ---------17 123 894 514 313 211 288 76 47
22 ---------17 119 797 483 320 200 258 84 47
23 ---------19 119 706 468 319 185 234 82 45
24 ---------21 135 646 464 317 171 216 80 44
25 ---------22 167 636 459 301 185 206 77 43
26 ---------23 203 641 463 276 219 190 75 42
27 ---------24 240 660 459 253 251 188 75 41
28 ---------24 340 670 461 251 296 278 68 41
29 ---------26 404 636 467 335 279 446 65 40
30 ---------27 499 617 470 391 248 442 62 39
31 ------------566 ---470 378 ---414 ---40
Mean ---------19 152 673 477 371 356 263 139 49
Min ---------16 28 440 432 251 171 169 62 39
Max ---------27 566 1005 616 521 665 446 370 60
#
# U.S. Geological Survey
# National Water Information System
# Retrieved: 2013-11-01 18:39:32 EDT
#
# ---------------------WARNING---------------------
# The data you have obtained from this automated
# U.S. Geological Survey database have not received
# Director's approval and as such are provisional
# and subject to revision. The data are released
# on the condition that neither the USGS nor the
# United States Government may be held liable for
# any damages resulting from its use.
#
# More data may be available offline.
# For more information on these data, contact Alaska Water Data Inquiries.
# This file contains the annual peak streamflow data.
#
# This information includes the following fields:
#
# agency_cd Agency Code
# site_no USGS station number
# peak_dt Date of peak streamflow (format YYYY-MM-DD)
# peak_tm Time of peak streamflow (24 hour format, 00:00 - 23:59)
# peak_va Annual peak streamflow value in cfs
# peak_cd Peak Discharge-Qualification codes (see explanation below)
# gage_ht Gage height for the associated peak streamflow in feet
# gage_ht_cd Gage height qualification codes
# year_last_pk Peak streamflow reported is the highest since this year
# ag_dt Date of maximum gage-height for water year (if not concurrent with peak)
# ag_tm Time of maximum gage-height for water year (if not concurrent with peak
# ag_gage_ht maximum Gage height for water year in feet (if not concurrent with peak
# ag_gage_ht_cd maximum Gage height code
#
# Sites in this file include:
# USGS 15246000 GRANT C NR MOOSE PASS AK
#
# Peak Streamflow-Qualification Codes(peak_cd):
# 1 ... Discharge is a Maximum Daily Average
# 2 ... Discharge is an Estimate
# 3 ... Discharge affected by Dam Failure
# 4 ... Discharge less than indicated value,
# which is Minimum Recordable Discharge at this site
# 5 ... Discharge affected to unknown degree by
# Regulation or Diversion
# 6 ... Discharge affected by Regulation or Diversion
# 7 ... Discharge is an Historic Peak
# 8 ... Discharge actually greater than indicated value
# 9 ... Discharge due to Snowmelt, Hurricane,
# Ice-Jam or Debris Dam breakup
# A ... Year of occurrence is unknown or not exact
# B ... Month or Day of occurrence is unknown or not exact
# C ... All or part of the record affected by Urbanization,
# Mining, Agricultural changes, Channelization, or other
# D ... Base Discharge changed during this year
# E ... Only Annual Maximum Peak available for this year
#
# Gage height qualification codes(gage_ht_cd,ag_gage_ht_cd):
# 1 ... Gage height affected by backwater
# 2 ... Gage height not the maximum for the year
# 3 ... Gage height at different site and(or) datum
# 4 ... Gage height below minimum recordable elevation
# 5 ... Gage height is an estimate
# 6 ... Gage datum changed during this year
#
#
agency_cd site_no peak_dt peak_tm peak_va peak_cd gage_ht gage_ht_cd year_last_pk ag_dt ag_tm
ag_gage_ht ag_gage_ht_cd
5s 15s 10d 6s 8s 27s 8s 13s 4s 10d 6s 8s 11s
USGS 15246000 1948-07-07 780 1
USGS 15246000 1949-09-04 800 1
USGS 15246000 1950-06-21 865 4.00
USGS 15246000 1951-07-08 665 1
USGS 15246000 1952-07-24 820 3.00 2 1952-06-28 3.36
USGS 15246000 1953-06-28 2230 4.46
USGS 15246000 1953-10-07 782 3.11
USGS 15246000 1955-07-11 1050 3.45
USGS 15246000 1956-08-20 663 2.93 2 1956-01-10 3.30 1
USGS 15246000 1957-09-03 1700 4.06
USGS 15246000 1958-06-21 1020 3.42
McMillen, LLC Homer Electric Association, Inc.
Grant Lake Hydroelectric Project
Appendix B: Supplemental Information
Regional Equations for Estimating Peak Streamflows 13
Table 3. Regression equations for estimating 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year peak streamflows for
unregulated streams in Regions 1-7, Alaska and conterminous basins in Canada
[QT, T-year peak streamflow, in cubic feet per second; A, drainage area, in square miles; ST, area of lakes and ponds
(storage), in percent; P, mean annual precipitation, in inches; J, mean minimum January temperature, in degrees
Fahrenheit; E, elevation, in feet; F, area of forest, in percent]
Regression equation for specified recurrence interval QT
Average
standard
error of
prediction
(log units)
Average
standard
error of
prediction
(percent)
Average
equivalent
years of
record
Region 1, Region 3 (93 gaging stations)
Applicable range of variables:
A: 0.720–571; ST: 0–26; P: 70–300; J: 0–32
Q2 = 0.004119 A0.8361 (ST+1)-0.3590 P 0.9110 (J+32)1.635 0.158 38 0.88
Q5 = 0.009024 A0.8322 (ST+1)-0.3670 P 0.8128 (J+32)1.640 .156 37 1.3
Q10 = 0.01450 A0.8306 (ST+1)-0.3691 P 0.7655 (J+32)1.622 .157 37 1.8
Q25 = 0.02522 A0.8292 (ST+1)-0.3697 P 0.7165 (J+32)1.588 .161 38 2.4
Q50 = 0.03711 A0.8286 (ST+1)-0.3693 P 0.6847 (J+32)1.559 .166 40 2.8
Q100 = 0.05364 A0.8281 (ST+1)-0.3683 P 0.6556 (J+32)1.527 .171 41 3.1
Q200 = 0.07658 A0.8276 (ST+1)-0.3669 P 0.6284 (J+32)1.495 .178 43 3.4
Q500 = 0.1209 A0.8272 (ST+1)-0.3646 P 0.5948 (J+32)1.449 .188 45 3.6
Region 2 (25 gaging stations)
Applicable range of variables:
A: 92.7–19,900; ST: 0–9; P: 12–100
Q2 = 0.7479 A0.9580 (ST+1)-0.03292 P 0.9284 .121 28 .82
Q5 = 1.021 A0.9449 (ST+1)-0.03603 P 0.9359 .116 27 1.5
Q10 = 1.184 A0.9368 (ST+1)-0.03813 P 0.9500 .119 28 2.0
Q25 = 1.374 A0.9274 (ST+1)-0.04074 P 0.9713 .129 30 2.5
Q50 = 1.506 A0.9209 (ST+1)-0.04263 P 0.9887 .141 33 2.7
Q100 = 1.628 A0.9147 (ST+1)-0.04448 P 1.007 .154 37 2.7
Q200 = 1.742 A0.9086 (ST+1)-0.04629 P 1.027 .168 40 2.7
Q500 = 1.880 A0.9008 (ST+1)-0.04864 P 1.056 .189 46 2.6
Region 4 (71 gaging stations)
Applicable range of variables:
A: 1.07–19,400; ST: 0–28; P: 20–158
Q2 = 0.2535 A0.9462 (ST+1)-0.1981 P 1.201 .177 42 .98
Q5 = 0.5171 A0.9084 (ST+1)-0.2128 P 1.162 .162 39 2.2
Q10 = 0.7445 A0.8887 (ST+1)-0.2204 P 1.147 .159 38 3.5
Q25 = 1.091 A0.8686 (ST+1)-0.2273 P 1.131 .164 39 5.0
Q50 = 1.395 A0.8563 (ST+1)-0.2313 P 1.120 .172 41 5.9
Q100 = 1.738 A0.8457 (ST+1)-0.2347 P 1.109 .183 44 6.6
Q200 = 2.124 A0.8363 (ST+1)-0.2377 P 1.099 .194 47 7.1
Q500 = 2.704 A0.8253 (ST+1)-0.2413 P 1.088 .212 52 7.4
1
3
2
6 5
4
7
1
3
2
6 5
4
7
1
3
2
6 5
4
7
44 Estimating the Magnitude and Frequency of Peak Streamflows for Ungaged Sites on Streams in Alaska and Conterminous Basins in Canada
15242000 Kasilof River near Kasilof, AK 4 60 19 05 151 15 35 738 1,810 15 39 50 10
15243950 Porcupine Creek near Primrose, AK 4 60 20 24 149 22 30 16.8 2,300 0 34 80 10
15244000 Ptarmigan Creek at Lawing, AK 4 60 24 20 149 21 45 32.6 2,800 6 46 90 10
15246000 Grant Creek near Moose Pass, AK 4 60 27 25 149 21 15 44.2 2,900 10 20 90 10
15248000 Trail River near Lawing, AK 4 60 26 01 149 22 19 181 2,470 2 9 90 10
15250000 Falls Creek near Lawing, AK 4 60 25 50 149 22 10 11.8 3,480 0 19 80 10
15251800 Quartz Creek at Gilpatricks, AK 4 60 35 45 49 32 35 9.41 3,260 0 11 60 10
15254000 Crescent Creek near Cooper Landing,
AK
4 60 29 49 149 40 38 31.7 2,700 13 38 50 8
152580001,R Kenai River at Cooper Landing, AK 4 60 29 34 149 48 28 634 2,650 5 13 70 10
152580001,2,R Kenai River at Cooper Landing, AK,
regulated years
4 61 29 34 150 48 28 634 2,650 5 13 70 10
15260000 Cooper Creek near Cooper Landing,
AK
4 60 26 00 149 49 15 31.8 2,400 16 44 60 8
15266300 Kenai River at Soldotna, AK 4 60 28 39 151 04 46 1,950 1,750 5 29 50 8
15266500 Beaver Creek near Kenai, AK 4 60 33 50 151 07 03 51.0 140 15 67 20 6
Table 4.Station information and peak-streamflow statistics for streamflow-gaging and partial-record stations in Alaska and conterminous basins in
Canada—Continued
[Rounding differences may cause values in this table to vary by less than 1 percent from those computed using equations in table 3 or by the computer
program available at http://pubs.water.usgs.gov/wri034188. Station No.: R, presently regulated. Station name: AK, Alaska; BC, British Columbia; YT,
Yukon. Region: See figure 1 for location of regions. Latitude and Longitude are given in degrees, minutes, and seconds. Mean basin elevation: Elevations
are given in feet above NGVD of 1929. Skew coefficient used for analysis: weighted skew except where noted in footnote. Peak streamflow analysis type:
Sta, value of QT from analysis of observed station data using weighted skew coefficient; Reg, value of QT estimated from regression equation (table 3); Wtd,
value of QT estimated by weighting Sta and Reg based on the years of record for station data and equivalent years of record for the equation. Peak
streamflow: QT, peak streamflow having a recurrence interval of T years. –, not available; ft, foot; mi2, square mile; in., inch; oF, degree Fahrenheit]
Station No. Station name Region Latitude Longitude
Drainage
area
(mi2)
Mean
basin
eleva-
tion
(ft)
Area of
lakes and
ponds
(storage)
(percent)
Area of
forest
(percent)
Mean
annual
precipi-
tation
(in.)
Mean
minimum
January
temper-
ature (oF)
1 Record includes glacial outbursts. Station not included in regression analysis. Station skew coefficient used to calculate QT.
2 Record includes regulated years. Station not included in regression analysis. Station skew coefficient used to calculate QT.
3 Drainage area is indeterminate. Station not included in regression analysis. Station skew coefficient used to calculate QT.
Table 4 45
15242000 25 0.158 Sta 8,080 9,890 11,000 12,400 13,400 14,400 15,400 16,700
Reg 8,300 10,900 12,700 15,000 16,800 18,500 20,300 22,700
Wtd 8,080 9,930 11,100 12,700 13,800 14,900 16,000 17,500
15243950 27 .939 Sta 772 1,290 1,790 2,640 3,490 4,550 5,900 8,250
Reg 706 1,090 1,390 1,800 2,110 2,440 2,780 3,270
Wtd 769 1,270 1,730 2,460 3,140 3,960 4,940 6,580
15244000 10 .380 Sta 523 703 832 1,000 1,140 1,280 1,430 1,650
Reg 1,040 1,510 1,870 2,350 2,710 3,080 3,470 4,010
Wtd 558 815 1,040 1,350 1,590 1,830 2,080 2,430
15246000 10 .962 Sta 936 1,330 1,660 2,170 2,620 3,140 3,760 4,730
Reg 1,260 1,810 2,220 2,760 3,170 3,590 4,020 4,620
Wtd 961 1,410 1,790 2,350 2,810 3,310 3,860 4,690
15248000 29 .609 Sta 3,670 4,840 5,700 6,890 7,860 8,890 10,000 11,600
Reg 6,200 8,600 10,400 12,600 14,300 16,000 17,800 20,300
Wtd 3,720 4,990 5,980 7,370 8,490 9,660 10,900 12,700
15250000 8 .349 Sta 242 452 642 951 1,240 1,580 1,990 2,650
Reg 505 793 1,020 1,320 1,560 1,810 2,070 2,440
Wtd 266 519 749 1,090 1,380 1,690 2,030 2,540
15251800 8 .867 Sta 166 319 478 773 1,090 1,510 2,060 3,100
Reg 289 462 599 785 932 1,090 1,250 1,480
Wtd 176 343 508 777 1,020 1,310 1,660 2,240
15254000 34 .750 Sta 331 519 682 939 1,180 1,460 1,790 2,330
Reg 434 643 799 1,010 1,170 1,330 1,510 1,750
Wtd 334 526 692 948 1,170 1,430 1,730 2,210
152580001,R 13 1.42 Sta 9,960 12,900 15,400 19,200 22,600 26,500 31,000 38,000
152580001,2,R 39 .372 Sta 11,100 14,800 17,400 20,800 23,500 26,400 29,300 33,500
15260000 10 .952 Sta 294 413 512 662 796 950 1,130 1,410
Reg 521 764 947 1,190 1,370 1,560 1,760 2,040
Wtd 310 465 605 812 982 1,170 1,360 1,660
15266300 35 .788 Sta 18,900 24,000 27,700 32,800 37,000 41,400 46,300 53,200
Reg 25,300 32,500 37,500 43,700 48,400 53,000 57,800 64,300
Wtd 19,000 24,200 28,100 33,400 37,700 42,300 47,200 54,200
15266500 25 .0559 Sta 188 357 501 721 914 1,130 1,380 1,750
Reg 221 332 414 524 610 699 793 925
Wtd 189 355 490 685 849 1,030 1,230 1,530
Table 4.Station information and peak-streamflow statistics for streamflow-gaging and partial-record stations in Alaska and conterminous basins in
Canada—Continued
[Rounding differences may cause values in this table to vary by less than 1 percent from those computed using equations in table 3 or by the computer program
available at http://pubs.water.usgs.gov/wri034188. Station No.: R, presently regulated. Station name: AK, Alaska; BC, British Columbia; YT, Yukon.
Region: See figure 1 for location of regions. Latitude and Longitude are given in degrees, minutes, and seconds. Mean basin elevation: Elevations are given
in feet above NGVD of 1929. Skew coefficient used for analysis: weighted skew except where noted in footnote. Peak streamflow analysis type: Sta, value
of QT from analysis of observed station data using weighted skew coefficient; Reg, value of QT estimated from regression equation (table 3); Wtd, value of QT
estimated by weighting Sta and Reg based on the years of record for station data and equivalent years of record for the equation. Peak streamflow: QT, peak
streamflow having a recurrence interval of T years. –, not available; ft, foot; mi2, square mile; in., inch; oF, degree Fahrenheit]
Station No.
Number
of
syste-
matic
peaks
Skew
coeffi-
cient
used for
analysis
Peak
stream-
flow
analysis
type
Peak streamflow, in cubic feet per second, for given recurrence interval, in years
Q2 Q5 Q10 Q25 Q50 Q100 Q200 Q500
Appendix A 87
15216000 Power Creek near Cordova, AK 1948-95 ––
15219000 West Fork Olsen Bay Creek near Cordova, AK 1965-80 ––
15219100 Control Creek near Cordova, AK 1964-74 ––
15227500 Mineral Creek near Valdez, AK 1976-81, 1990-99 ––
15236200 Shakespeare Creek at Whittier, AK 1970-80, 1984-99 ––
15237360 San Juan River near Seward, AK 1987-96 ––
15237400 Chalmers River near Cordova, AK 1967-73, 1975-80 ––
15238000 Lost Creek near Seward, AK 1949, 1963-72, 1976, 1987 1976,
1987
51
15238600 Spruce Creek near Seward, AK 1966-86, 1988-99 ––
15238820 Barabara Creek near Seldovia, AK 1973-92 ––
15239000 Bradley River near Homer, AK 1958-88 ––
15239050 Middle Fork Bradley River tributary near Homer, AK 1980-99 ––
15239500 Fritz Creek near Homer, AK 1963-99 ––
15239800 Diamond Creek near Homer, AK 1963-81 ––
15239900 Anchor River near Anchor Point, AK 1966-74, 1979-87, 1992 –48
15240000 Anchor River at Anchor Point, AK 1954-66, 1984-92 –48
15240500 Cook Inlet tributary near Ninilchik, AK 1966-81 ––
15241600 Ninilchik River at Ninilchik, AK 1963-85, 1999 ––
15242000 Kasilof River near Kasilof, AK 1950-74, 1977 1977 28
15243950 Porcupine Creek near Primrose, AK 1963-89 ––
15244000 Ptarmigan Creek at Lawing, AK 1948-50, 1952-58 ––
15246000 Grant Creek near Moose Pass, AK 1948-50, 1952-58 ––
15248000 Trail River near Lawing, AK 1948-50, 1952-77 ––
15250000 Falls Creek near Lawing, AK 1963-70 ––
15251800 Quartz Creek at Gilpatricks, AK 1963-70, 1987 1987 25
15254000 Crescent Creek near Cooper Landing, AK 1950-83 ––
15258000 Kenai River at Cooper Landing, AK 1948-60 ––
15258000 Kenai River at Cooper Landing, AK, regulated years 1961-99 ––
15260000 Cooper Creek near Cooper Landing, AK 1950-59 ––
15266300 Kenai River at Soldotna, AK 1965-99 –47
15266500 Beaver Creek near Kenai, AK 1968-78, 1980-83, 1985-94 ––
15267900 Resurrection Creek near Hope, AK 1968-85 ––
15269500 Granite Creek near Portage, AK 1967-80 ––
15270400 Donaldson Creek near Wibel, AK 1963-72 ––
15271000 Sixmile Creek near Hope, AK 1980-90, 1998-99 ––
15271900 Cub Creek near Hope, AK 1965-79 ––
15272280 Portage Creek at Portage Lake outlet near Whittier, AK 1989-99 ––
15272530 California Creek at Girdwood, AK 1967-84, 1986-93, 1995 1995 28
15272550 Glacier Creek at Girdwood, AK 1966-78 ––
15273900 South Fork Campbell Creek at canyon mouth near
Anchorage, AK
1967-79, 1981 ––
15274000 South Fork Campbell Creek near Anchorage, AK 1948-72, 1999 ––
15274300 North Fork Campbell Creek near Anchorage, AK 1967-84 ––
Appendix A. Years of record for annual peak streamflows used in this report—Continued
[Refer to table 4 for number of systematic peaks used; AK, Alaska; BC, British Columbia; YT, Yukon]
Station No. Station name
Water years for peak streamflows
(systematic and historic) used in this
report
Water
years for
historic
peaks used
in this
report
Length of
historic
period
(years)
Gulf of AlaskaPacific OceanBristol BayBering SeaArctic OceanBeaufort SeaNortonSoundHecate StraitYukonRiverColvilleRiverKuskokwimRiverTananaRiverPorcupineSusitnaKoyukukRiverYukonRiverLiardRiverRiver Copper River RiverBritishColumbiaYukonAnchorageFairbanksNomeWhitehorseJuneauBarrowB r o o k s R a n g eCoast MountainsAlaska
Canada
KenaiPeninsula7564213A l a s k a R a n g eA l e u t i a n R a n g eRUSSIAStreamflow analysis region boundary and region numberEXPLANATION1Streamflow-gaging station and number, peak flow analysis15565447 A R C T I C C I R C L EKupreanofPetersburgKlukwanPort ProtectionPoint BakerEdna BayElfin CoveHyderHollisThorne BayCoffman CoveHoonahTenakeeSpringsPelicanAngoonPort AlexanderHydaburgKasaanKlawockCraigMetlakatlaSaxmanWrangellKakeKetchikanHainesJuneauSkagwaySitkaGulf of AlaskaCookInletTurnagain ArmKnik ArmTustumena LakeKenaiPeninsula4312EklutnaBig LakeNikiskiSalamatofKasilofClam GulchNinilchikTyonekMoose PassCooper LandingHopePort GrahamPortlockNanwalekAnchor PointNikolaevskKnikSeldoviaHomerKachemakSewardSoldotnaKenaiWasillaPalmerAnchorageWhittierGlacier iceRoadEXPLANATIONGlacier iceEXPLANATIONCross SoundL y nn Canal Icy StraitFrederickSoundStephensP a s s ag e Ch a tham Stra itClarence StraitDixon EntranceChristianSound15798700157470001574450015744000157438501556460015564800153036001530366015304000155654471530429815304293153042001530200015300200153005001529790015303011153030101530290015302500153030001530315015300000155652001558500015621000156190001563300015624998156250001566820015635000156370001571200015896000158967001591820015904900159060001590800015910000159102001556486815564872155648791556487715564875153895001556488715564885155648841545361015453481154535001546800015457800154577001551920015541650155416001551900015541800155200001553000015490000155350001544250015438500154398001551825015518200154800001547809315478000154785001547849915476400154762001547630015515500155145001548400015493000154855001551400015511000154935001556490015305590153054061530370015668100159999001538894815388944153889501538896015389000153550001534400015348000153650001535600015367500154715001530595015305920153059001547100015469900154703401547033015470300154700001547395015473600151985001519900015476000155162001551605015516000155158001551590015518000155183501547805015478040154760501547604915305670153056501530545015305695153057001530569815305620153055821530542015305360153053501530530015305412153054001530539015305260153051001530525015305050153050301530500015304950151205001512000015305500153055401520910015209000152000001520028015200270152915001547801015291100152912001529100015294025152928001529239215293000152945001529400515293700152941001529401015292700152924001529200015294300152902001520110015282400152815001528200015206000152020001520100015201900152374001529000015283500152850001520820015208100152080001521170015213400152125001521190015212000151950001521600015219000152191001521280015227500152373601551808015305150153052001530452015304750153048501512950015120600151207201530485515304800153046001502460015024500150243001502420015024400150246701502468415297475152972001529600015295600150880001500800015015590150100001502200015011500150835001505800015094000150934001508759015087570150875451508660015028300150248001502475015100000150980001510200015108000150575001508758515087250150869001508149015056210150562001505610015056560151069401510696015106920151070001510698015081497150815001508510015085800150857001507200015059500150600001506800015067900150876901508560015085600150818901508158015080000150780001507600015074000150700001502600015012000151082501510150015101490150545001504120015040000150440001505200015050000150499001505280015048000150360001503400015038000150310001503990015109000150525001505400015053800152800001527720015272530152719001527040015269500152600001525180015248000152439501524050015239800152395001523800015236200152943501527741015284000152810001527710015276000152743001527400015273900152580001525400015250000152460001524400015238600152390501523900015240000152399001523882015242000152416001526650015266300152944501527228015272550152710001526790015024690150247001502469515024640150411001504100015304650153047000 200 400 500100 300600 MILES0 200 400 600 800100 300 500 700900 KILOMETERS0 40 80 120 160 MILES0 40 80 120 160 200 KILOMETERS0 10 20 30 40 MILES0 10 20 30 40 50 KILOMETERSCurran, J.H., and others, 2003, Estimating the magnitude and frequency of peak streamflowsfor ungaged sites on streams in Alaska and conterminous basins in CanadaByJanet H. Curran, David F. Meyer, and Gary D. Tasker 2003MAP SHOWING STREAMFLOW ANALYSIS REGIONS AND LOCATIONS OF STREAMFLOW-GAGING AND PARTIAL-RECORD STATIONSFOR WHICH PEAK-STREAMFLOW STATISTICS WERE COMPUTED, ALASKA AND CONTERMINOUS BASINS IN CANADAU.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEYPREPARED IN COOPERATION WITH THEALASKA DEPARTMENT OF TRANSPORTATION AND PUBLIC FACILITIESWATER-RESOURCES INVESTIGATIONS REPORT 03Ð4188Magnitude and frequency of peak streamflowsÑPLATE 1