HomeMy WebLinkAbout3.9 TM003-Grant Lake Hydroelectic Project Operations and Fisheries Habitat - FinalTECHNICAL MEMORANDUM 003
EMORANNO. 001EMORANNO. 001
McMillen, LLC Page 1 Homer Electric Association, Inc.
June 2014 Grant Lake Hydroelectric Project
To: Mike Salzetti, HEA Project: Grant Lake Hydroelectric Project
From: Cory Warnock Cc: Mort McMillen, Andre Ball, John
Blum
Date: June 27, 2014 Job No: 13-102
Subject: Grant Lake Hydroelectric Project Operations and Fisheries Habitat
1.0 INTRODUCTION
McMillen, LLC (McMillen) has been retained by Homer Electric Association (HEA) to provide
licensing, natural resource and engineering support for the proposed Grant Lake Hydroelectric
Project (Project) FERC License Application. The project would be located near the city of Moose
Pass, Alaska, approximately 25 miles north of Seward, Alaska.
A suite of natural resource studies (fisheries, water resources, terrestrial, cultural and
recreation/visual) were developed in collaboration with Stakeholders in 2012 and implemented in
2013 and 2014. While comprehensive and quantitative in their own right, these studies were
further supplemented by data collected by HEA data in 2009/2010, as well as historical natural
resource data collected on Grant Creek. Simultaneous with the natural resources work, HEA has
been refining the Project infrastructural description and carrying out the engineering analyses
required to accurately define the operational aspects of the project in preparation for License
Application submittal.
1.1 Purpose and Scope
The purpose of this technical memorandum (TM) is to present HEA’s proposed Grant Lake
Hydroelectric Project operations, instream flow regime in Reach 5, and to discuss the potential
impacts to fisheries and instream flows on Grant Creek. The operations analysis presented within
this TM build upon previous studies. The scope of information presented in this TM is as follows:
Summary of Grant Lake fisheries and water resources
Proposed project infrastructure
Proposed project operations and energy generation analysis
Project impacts to fisheries habitat and instream flows
McMillen, LLC Page 2 Homer Electric Association, Inc.
June 2014 Grant Lake Hydroelectric Project
2.0 GRANT CREEK FISHERIES AND WATER RESCOURCES
Grant Creek is the only natural outlet from Grant Lake and is located at the south end of the lake
(Figure 1, Appendix A). Grant Creek flows west from Grant Lake for about a mile before flowing
into the Trail Lake Narrows. During the 2013/2014 natural resource studies, Grant Creek was
divided into six different reaches (Reaches 1-6, Figure 1). All anadromous species are precluded
from upstream movement into Grant Lake by an impassible falls located at the Reach 5 – Reach 6
transition. The only resident fish species that reside in Grant Lake are sculpin and stickleback. An
extensive set of fisheries investigations were conducted in 2013, which documented four
anadromous species of salmon (Chinook, Sockeye, Coho and Pink salmon) along with Rainbow
trout and Dolly Varden char in Grant Creek. Species of sculpin and stickleback were also
documented in Grant Creek.
Grant Creek experiences large variations in flow on a seasonal basis due to snowmelt in the early
summer (June/July) and rainfall events later in the summer/fall. Minimum flows in late winter
typically range between 15-20 cubic feet per second (cfs), while peak flows in the summer or fall
exceed 1000 cfs frequently. The primary sediment input for Grant Creek is associated with the
shearing of extremely angular material during episodic high flow events through the steep-walled
canyon in Reach 5. Given the relatively low quality of the overall substrate composition in
Reaches 1-4, spawning tends to be opportunistic and focused on areas where pockets of higher
quality spawning substrates exists. Rearing tends to be associated with stream margins and a few
primary side channels that exist.
Table 1 (Appendix A) documents the periodicity for the various life stages of the fish species
discussed above, along with relevant Grant Creek streamflow statistics.
2.1 Fisheries and Habitat
Grant Creek is a high gradient stream with high streamflow velocities. High flows and velocities
limit the amount of large woody debris (LWD) retained in the system, since there are only a few
places where LWD will collect in the main channel. Most wood is found in the distributary and
the Reach 2/3 side channels, where flows are greatly reduced and are protected from the main
discharges in Grant Creek. The system is dominated by riffles in the lower four reaches and
cascades in Reach 5. Pools are also generally lacking in the mainstem. As with LWD, the
exception is in the side channels and distributary. The other major habitat found with some
abundance is undercut banks, primarily in Reaches 1 and 4 (see Tables 2 and 3).
Low winter flows may affect incubation and winter rearing of juveniles and fry. Side channels,
which provide excellent rearing habitat for juvenile fish, are either dry at lower flows (in the case
of the distributary in Reach 1), or have extremely low flows during winter time (in the Reach 2/3
side channels) and may freeze. Spawning substrate throughout lower Grant Creek (Reaches 1 –
4) is limited, and salmonid spawning may be more a function of suitable substrates than
preferred depths and velocities. Since much of the preferred substrates are found along the
stream margins where they are dropped during high flows, eggs deposited along the banks at
high flows may be subject to desiccation when those high flow recede. This may be a factor
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June 2014 Grant Lake Hydroelectric Project
especially early during the spawning period for Chinook and Sockeye salmon when they spawn
on the receding hydrograph (see periodicity and hydrology data in Table 1 of Appendix A).
McMillen, LLC Page 4 Homer Electric Association, Inc. June 2014 Grant Lake Hydroelectric Project Table 2. Mesohabitats found in Grant Creek. Habitat Type Total Area (Sq. Ft) Reach 1 Distributary Reach 1 MainstemReach 2 Backwater Habitat Reach 2 MainstemReach 2 Secondary Channel Reach 3 Backwater Habitat Reach 3 MainstemReach 3 Primary Side ChannelReach 3 Secondary Channel Reach 4 MainstemReach 5 MainstemBackwater 8,534 0 0 4,837 0 0 3,697 0 0 0 0 0 Cascade 33,707 0 0 0 0 114 0 0 0 0 0 33,593 Glide 3,202 0 0 0 1,613 0 0 0 0 1,588 0 0 Pocket water 3,709 0 0 0 0 0 0 0 0 0 3,709 0 Pool 42,568 7,495 3,143 0 3,834 398 0 3,997 5,018 9,510 1,195 7,977 Rapid 511 0 0 0 0 0 0 0 511 0 0 0 Riffle 110,429 6,004 23,168 0 23,669 1,189 0 25,585 11,672 1,493 17,649 0 Run 576 0 0 0 0 0 0 0 0 576 0 0 Step Pool 16,858 0 0 0 0 0 0 0 0 0 0 16,858 Table 3. Aquatic habitats found in Grant Creek. Habitat Type Total Area (Sq. Ft) Reach 1 Distributary Reach 1 MainstemReach 2 Backwater Habitat Reach 2 MainstemReach 2 Secondary Channel Reach 3 Backwater Habitat Reach 3 MainstemReach 3 Primary Side Channel Reach 3 Secondary Channel Reach 4 MainstemReach 5 MainstemMargin 7,214 0 3,343 0 3,871 0 0 0 0 0 0 0 Overhead Vegetation (OHV) 10,096 302 0 0 0 0 0 0 2,455 7,339 0 0 UCB 12,187 1,513 3,372 0 2,193 0 0 278 110 1,214 3,216 0 Large Woody Debris (LWD) 17,750 3,556 1,894 0 182 0 0 1,142 1,611 6,218 3,040 0
McMillen, LLC Page 5 Homer Electric Association, Inc.
June 2014 Grant Lake Hydroelectric Project
2.2 Hydrology
The streamflow record utilized for the Grant Creek habitat assessment and energy analysis is a
combination of recorded streamflow and record extension. Grant Creek has an 11-year USGS
streamflow gage record for water years 1948-1958 at USGS gage 15246000. Intermittent
streamflow monitoring was conducted in 1981-83, 2009 and from 2013 to present. A record
extension was performed based on the USGS gage 15258000, Kenai River at Cooper Landing,
record. A composite streamflow record was created for Grant Creek that represents of 66 years of
daily streamflow data for calendar years 1948 through 2013. The Grant Creek hydrology and
streamflow records are discussed in greater detail in a separate technical memorandum, TM001
Grant Creek Hydrologic Analysis (McMillen, 2014).
Monthly streamflow statistics for the Grant Creek composite record are provided in Table 1 of
Appendix A. Based on the average annual hydrograph, flows are lowest, around 34 cfs, in Grant
Creek during March and April. Flows begin to rise in May and June due to snow melt and tend to
peak in July (503 cfs). Flow values then taper off by an order of magnitude from August through
February (444 cfs to 43 cfs).
3.0 PROPOSED PROJECT INFRASTRUCTURE
As outlined in HEA’s 2011 application for a preliminary permit, 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 downstream from Reach 5. The Project would include the following major components:
An intake structure in Grant Lake.
A tunnel extending from the lake intake to just east of the powerhouse.
A penstock and surge tank located at the west end of the tunnel.
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.
Access road from the Seward Highway to the powerhouse and extending up to the intake
structure at Grant Lake.
A pole mounted disconnect switch where the transmission line intersects the main power
distribution line.
The layout has been revised to minimize the Project footprint. The current design omits the
construction of a diversion structure (dam) at the outlet of Grant Lake. All 13-feet of storage that
will be utilized for power generation will be drawn from below the natural lake outlet. The tailrace
channel, which returns flow from the powerhouse to Grant Creek, will be located at the upstream
of Reach 4. This tailrace location ensures that the reaches with the best natural habitat for fish will
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June 2014 Grant Lake Hydroelectric Project
not be dewatered. The detention pond will be utilized to allow the powerhouse to meet the spinning
reserve without resulting in drastic changes to in-channel flows.
4.0 PROPOSED PROJECT OPERATIONS
The proposed Project operations will utilize Grant Lake as a natural storage reservoir. This will
allow the Project to regulate the lake outflow, which will result in year round power generation
and consistent instream flows. On a typical year, Grant Lake will be operated following a rule
curve. The rule curve will maintain the lake at the full level from mid-August through October.
Beginning in November, when natural runoff begins to taper off, the lake level will be drafted to
provide additional power generation. The lake will be lowered by a maximum of 13 feet during
winter. In late spring and through mid-summer, the lake will be refilled with snowmelt runoff.
The regulated outflow from Grant Lake will be run through the powerhouse. With two,
asymmetrically-sized turbines, the Project will be able to efficiently generate power over a range
of discharges. After passing through the powerhouse, the flow will be returned to Grant Creek at
the upstream end of Reach 4. In order to maintain a wetted channel throughout Grant Creek,
instream flow releases are proposed for the Reach 5 and 6 section between Grant Lake and the
powerhouse. The proposed instream flow releases would provide 10 cfs in Reach 5 during the
Chinook spawning period and continue to provide 7 cfs through the Coho spawning period. During
the remainder of the year, 5 cfs would be passed through Reach 5.
An energy generation model was developed to simulate the Project under these proposed
operations. Utilizing the average daily inflows from the composite record, the anticipated annual
energy production would be 19,500,000 kilowatt-hours. Table 4 (Appendix A) summarizes the
average weekly flows in Grant Creek, with and without the Project.
5.0 PROJECT IMPACTS TO FISHERIES HABITAT AND INSTREAM FLOWS
The flow regime, as proposed, would increase winter flows while decreasing the peak flows found
during snow melt and episodic rain events throughout the year. The Project, as proposed to be
operated, would provide more stable flows throughout the year. Winter flows (November –
February) would be increased over natural flows. The Project would closely mimic natural flows
during March, April, September, and October. The Project would reduce mean flows during June,
July and August period (Table 4).
Based on the proposed operational regime, the implications to the instream flows for Reach 5 and
Reaches 1-4 are described below.
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June 2014 Grant Lake Hydroelectric Project
5.1 Reach 5 Instream Flows
HEA proposes to provide an instream flow through Reaches 5 and 6 accordingly (see Table 4 in
Appendix A):
5 cfs (January 1 – July 31; November 1 – December 31. Rainbow trout spawning from
May 16 – June 30)
10 cfs (August 1 – September 7; Chinook and Sockeye salmon and Dolly Varden char
spawning)
7 cfs (September 8 – October 31; Sockeye and Coho salmon and Dolly Varden char
spawning)
Flows are proposed to provide sufficient passage for adult salmonids which may utilize Reach 5.
Surveys in 2013, however, indicated limited use of the canyon. Of the 388 adult salmon noted
during the 2013 surveys, only 3 Sockeye and 2 Coho salmon were observed in Reach 5. These fish
constitute 1.3% of the total observed population.
Connectivity for Sockeye and Coho salmon, based on the 2013 study, indicated that connectivity
was provided at a flow of 10 cfs, with trout connectivity provided at a flow of 5 cfs [Note: data
for trout were re-analyzed after the submission to the Instream Flow study report]. Chinook
connectivity is achieved at flows ranging from 25 – 30 cfs; however, no Chinook have been
observed in Reach 5.
HEA proposes additional flows in the Reach 2/3 side channels during the November – February
period, which increases habitat for rearing salmonids in Grant Creek. This metric is discussed in
the following section.
5.2 Reach 1-4 Flows
In general, maximum habitat (as measured by Weighted Usable Area, WUA) in Grant Creek
occurs at flows ranging from approximately 300 cfs to 400 cfs, as measured at the Grant Creek
stream gauge. There are specific instances when higher flows maximize WUA. In Reach1 (main
channel), rearing habitat increases with flow throughout the modeled range. In Reach 3
(mainstem), habitat for spawning and fry, juvenile and adult rearing, is maximized at flows of
approximately 100 cfs and then generally decreases as flow increases above 100 cfs..
A preliminary look at WUA for Chinook and Sockeye salmon indicates no net loss in spawning
habitat, with a slight overall increase (approximately 1%). Coho salmon spawning habitat remains
the same since flows during the spawning period are the same, pre- and post-project. Overall
decreases in Dolly Varden and Rainbow trout adult rearing WUA is approximately 10% for the
June – August period.
Due to reduced flows in the Reach 2/3 side channels during the summer months, there is a slight
decrease in habitat during this period. However, there are marked increases in overwintering
habitat for Chinook salmon, Dolly Varden char, and Rainbow trout. Overall, Chinook juvenile
habitat increased by over 56%, Rainbow trout rearing increase by over 10%, and Dolly Varden
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June 2014 Grant Lake Hydroelectric Project
juvenile habitat increased by over 6%. The overall increase in habitat over this period was 17.2%.
Coho salmon juvenile habitat decreased overall by 1%, ranging from a decrease of over 5% in
WUA during January, to an increase of over 8% in November (Table 5).
In the Reach 2/3 side channels, flows are decreased during the June – August period. There are
losses in fry, juvenile, and adult rearing WUA of 3%, 9% and 16% respectively in these side
channels for this period.
Table 5. Changes in WUA for rearing salmonids in the Reach 2/3 side channels, comparing pre-
Project to proposed Project flows.
Species/Life Stage Jan Feb Nov Dec Mean
Chinook Juvenile 167.8% 178.6% 129.9% 150.2% 156.6%
Coho Juvenile 94.4% 96.7% 108.1% 96.8% 99.0%
Dolly Varden Juvenile 106.9% 116.0% 102.2% 101.5% 106.7%
Rainbow Juvenile 112.9% 123.0% 103.4% 105.1% 111.1%
Rainbow Fry 119.7% 127.2% 95.7% 108.7% 112.8%
Mean 120.3% 128.3% 107.9% 112.5% 117.2%
6.0 SUMMARY AND CONCLUSIONS
This technical memorandum was intended to provide specific details related to HEA’s proposed
operational regime for the Grant Lake Project. Also outlined, were HEA’s proposed instream flow
releases for Reaches 5 and 6 (bypass reach) that are intended to permit the small number of fish
currently utilizing the area to continue to do so. Under natural conditions, Reach 5 has the least
area of habitat suitable for spawning and rearing. The operational scenario outlined and the
resulting instream flows in Reaches 1-4 should provide a more stable condition that amplifies and
maintains habitat in the mainstem and side channels. The side channels are highly valued for their
habitat that provides some of the best spawning and rearing potential in Grant Creek. Based on the
analysis of the proposed Project operations that has been conducted, this increase in habitat in the
Reach 2/3 side channel complex will far exceed any loss of habitat that may occur in Reach 5 area.
HEA has proactively developed this operational scenario and associated instream flow regime
based both upon the data that was collected during the 2013 study program and the quality
amount of consultation that has taken place with all of the Stakeholders. We want to emphasize
that the scenario described in this memo represents a realistic and somewhat unique opportunity
for HEA to responsibly develop the Grant Lake Project while at the same time, positively impact
the aquatic environment by generating more abundant, stable and consistent habitat than is
currently present under natural conditions. HEA looks forward to discussing this memo with the
Stakeholders, answering questions and collaborating on the details related to this proposal. The
ultimate goal for HEA as it relates to Stakeholder consultation is to develop the most
collaborative FERC License Application possible. We sincerely hope that this memo and the
associated discussions during our July 2014 meeting will greatly assist in that development.
McMillen, LLC Page 9 Homer Electric Association, Inc.
June 2014 Grant Lake Hydroelectric Project
7.0 REFERENCES
McMillen, 2014. TM 001: Grant Creek Hydrologic Analysis. Prepared for Homer Electric
Association.
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June 2014 Grant Lake Hydroelectric Project
8.0 APPENDIX A
Figure 1. Grant Creek Reaches and Project Infrastructure
Table 1. Grant Creek Biology, Hydrology, and Operations Summary
Table 4. Grant Creek Instream Flows under Natural Conditions and with Project Operations
Developed For:
Drawing Scale:
GRANT LAKE HYDROELECTRIC PROJECT - FERC PROJECT #P-13212
TM003: Grant Lake Hydroelectric Project Operations and Fisheries Habitat
Figure 1.Grant Creek Reaches and Project Infrastructure
±1401 Shoreline DriveSuite 100Boise, ID 83702
OFFICE: 208.342.4214FAX: 208.342.4216
REV DESCRIPTIONBYDATE SCALE:
DRAWING
ISSUED DATE
CHECKED
DRAWN
DESIGNED
0 300 600150
Feet
LowerTrailLake
6/18/2014
A. Ball
A. Ball
C. Warnock
Legend
Reach Breaks
1:4,000
TrailLake Narrows
G r a n t C r e e k
Detention Pond Outlet
Tailrace
Powerhouse
Detention Pond
Transmission Line Access Road
Tunnel
Intake
UpperTrailLake
GrantLake
Reach 6
Reach 5Reach 4Reach 3Reach 2Reach 1
Penstock
StageMaximum Flow20% ExceedanceAverage FlowMedian Flow80% ExceedanceMinimum Flow5555555555555555555555555555101010101077777775555555555 51 51 52 47 45 41 39 36 34 32 31 30 31 35 45 69 101 152 227 318 382 431 483 494 517 507 496 484 469 440 402 379 347 379 364 280 272 216 184 159 133 109 99 92 74 67 63133 128 128 128 124 119 115 106 36 34 33 30 30 30 35 46 68 97 155 224 199 260 310 360 370 390 388 375 365 347 395 399 395 374 372 365 282 273 212 187 234 207 185 180 172 150 141 147989987766655556812172538536472818286848381787367635863614745363126221816151211102221212121201918665555681116263733435260626565636158666766626261474635313935313029252424FillingDraftingMinimum ElevationApproximate Reach 2/3 Side Channel Flow - NaturalApproximate Reach 2/3 Side Channel Flow - with ProjectBiological ParametersInstream Flow Release (Reach 5)(cfs)Main Channel Flow (Reach 1-4) - NaturalMain Channel Flow (Reach 1-4) - with ProjectReservoir Rule CurveMaximum ElevationDrafting/FillingDraftingTable 2. Grant Creek Instream Flows under Natural Conditions and with Project OperationsJanuary February March April May June July August September October November DecemberRunning Running OffOff Off RunningRunning Running RunningOperationsTypical Unit Operation1 MW Unit (75 cfs)Running Running Running210 173 654 MW Unit (310 cfs)Off Off Off Off Running RunningRunning Running OffRunning Running Running45 28 1812 11 6 13 17 102419 346 215 115 67 4232 25 21 22 62 290488 422 313 182 94 5945 36 30 31 127 398503 444 367 233 123 7352 43 33 36 146 409573 524 480 317 151 8764 51 41 47 215 5121210 1383 1731 1295 851 570326 227 116 160 566 2140AdultDolly VardenRainbowHydrologyComposite Streamflow Record (CY 1948-2013)(cfs)FryChinookCohoSockeyeDolly VardenRainbowCohoSockeyeDolly VardenRainbowIncubatingChinookCohoSockeyeDolly VardenRainbowOctober November DecemberTable 1. Grant Creek Biology, Hydrology, and Operations Summary TableBiologySpecies January February March April May JuneSpawningChinookCohoSockeyeDolly VardenRainbowJuly August SeptemberJuvenilesChinookMcMillen, LLC June 2014Homer Electric Association, Inc.Grant Lake Hydroelectric Project